also for #2771 - removal of all MDBX utilities and libmdbx.mir itself

1 files changed, 0 insertions, 5017 deletions

diff --git a/libs/libmdbx/src/mdbx.h b/libs/libmdbx/src/mdbx.h
deleted file mode 100644
index 9d7dba99e9..0000000000
--- a/libs/libmdbx/src/mdbx.h
+++ /dev/null
@@ -1,5017 +0,0 @@
-/**
-
-_libmdbx_ is an extremely fast, compact, powerful, embedded,
-transactional [key-value
-store](https://en.wikipedia.org/wiki/Key-value_database) database, with
-[permissive license](./LICENSE). _MDBX_ has a specific set of properties and
-capabilities, focused on creating unique lightweight solutions with
-extraordinary performance.
-
-_libmdbx_ is superior to [LMDB](https://bit.ly/26ts7tL) in terms of features
-and reliability, not inferior in performance. In comparison to LMDB, _libmdbx_
-makes many things just work perfectly, not silently and catastrophically
-break down. _libmdbx_ supports Linux, Windows, MacOS, OSX, iOS, Android,
-FreeBSD, DragonFly, Solaris, OpenSolaris, OpenIndiana, NetBSD, OpenBSD and other
-systems compliant with POSIX.1-2008.
-
-_The Future will (be) [Positive](https://www.ptsecurity.com). Всё будет хорошо._
-
-
-\section copyright LICENSE & COPYRIGHT
-
-\authors Copyright (c) 2015-2021, Leonid Yuriev <leo@yuriev.ru>
-and other _libmdbx_ authors: please see [AUTHORS](./AUTHORS) file.
-
-\copyright Redistribution and use in source and binary forms, with or without
-modification, are permitted only as authorized by the OpenLDAP Public License.
-
-A copy of this license is available in the file LICENSE in the
-top-level directory of the distribution or, alternatively, at
-<http://www.OpenLDAP.org/license.html>.
-
- ---
-
-This code is derived from "LMDB engine" written by
-Howard Chu (Symas Corporation), which itself derived from btree.c
-written by Martin Hedenfalk.
-
- ---
-
-Portions Copyright 2011-2015 Howard Chu, Symas Corp. All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted only as authorized by the OpenLDAP
-Public License.
-
-A copy of this license is available in the file LICENSE in the
-top-level directory of the distribution or, alternatively, at
-<http://www.OpenLDAP.org/license.html>.
-
- ---
-
-Portions Copyright (c) 2009, 2010 Martin Hedenfalk <martin@bzero.se>
-
-Permission to use, copy, modify, and distribute this software for any
-purpose with or without fee is hereby granted, provided that the above
-copyright notice and this permission notice appear in all copies.
-
-THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
-ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-
-*******************************************************************************/
-
-#pragma once
-#ifndef LIBMDBX_H
-#define LIBMDBX_H
-
-#ifdef _MSC_VER
-#pragma warning(push, 1)
-#pragma warning(disable : 4548) /* expression before comma has no effect;      \
-                                   expected expression with side - effect */
-#pragma warning(disable : 4530) /* C++ exception handler used, but unwind      \
-                                 * semantics are not enabled. Specify /EHsc */
-#pragma warning(disable : 4577) /* 'noexcept' used with no exception handling  \
-                                 * mode specified; termination on exception is \
-                                 * not guaranteed. Specify /EHsc */
-#endif                          /* _MSC_VER (warnings) */
-
-/* *INDENT-OFF* */
-/* clang-format off */
-
-/**
- \file mdbx.h
- \brief The libmdbx C API header file
-
- \defgroup c_api C API
- @{
- \defgroup c_err Error handling
- \defgroup c_opening Opening & Closing
- \defgroup c_transactions Transactions
- \defgroup c_dbi Databases
- \defgroup c_crud Create/Read/Update/Delete (see Quick Reference in details)
-
- \details
- \anchor c_crud_hints
-# Quick Reference for Insert/Update/Delete operations
-
-Historically, libmdbx inherits the API basis from LMDB, where it is often
-difficult to select flags/options and functions for the desired operation.
-So it is recommend using this hints.
-
-## Databases with UNIQUE keys
-
-In databases created without the \ref MDBX_DUPSORT option, keys are always
-unique. Thus always a single value corresponds to the each key, and so there
-are only a few cases of changing data.
-
-| Case                                        | Flags to use        | Result                 |
-|---------------------------------------------|---------------------|------------------------|
-| _INSERTING_|||
-|Key is absent → Insertion                    |\ref MDBX_NOOVERWRITE|Insertion               |
-|Key exist → Error since key present          |\ref MDBX_NOOVERWRITE|Error \ref MDBX_KEYEXIST and return Present value|
-| _UPSERTING_|||
-|Key is absent → Insertion                    |\ref MDBX_UPSERT     |Insertion               |
-|Key exist → Update                           |\ref MDBX_UPSERT     |Update                  |
-|  _UPDATING_|||
-|Key is absent → Error since no such key      |\ref MDBX_CURRENT    |Error \ref MDBX_NOTFOUND|
-|Key exist → Update                           |\ref MDBX_CURRENT    |Update value            |
-| _DELETING_|||
-|Key is absent → Error since no such key      |\ref mdbx_del() or \ref mdbx_replace()|Error \ref MDBX_NOTFOUND|
-|Key exist → Delete by key                    |\ref mdbx_del() with the parameter `data = NULL`|Deletion|
-|Key exist → Delete by key with with data matching check|\ref mdbx_del() with the parameter `data` filled with the value which should be match for deletion|Deletion or \ref MDBX_NOTFOUND if the value does not match|
-|Delete at the current cursor position        |\ref mdbx_cursor_del() with \ref MDBX_CURRENT flag|Deletion|
-|Extract (read & delete) value by the key     |\ref mdbx_replace() with zero flag and parameter `new_data = NULL`|Returning a deleted value|
-
-
-## Databases with NON-UNIQUE keys
-
-In databases created with the \ref MDBX_DUPSORT (Sorted Duplicates) option, keys
-may be non unique. Such non-unique keys in a key-value database may be treated
-as a duplicates or as like a multiple values corresponds to keys.
-
-
-| Case                                        | Flags to use        | Result                 |
-|---------------------------------------------|---------------------|------------------------|
-| _INSERTING_|||
-|Key is absent → Insertion                    |\ref MDBX_NOOVERWRITE|Insertion|
-|Key exist → Needn't to add new values        |\ref MDBX_NOOVERWRITE|Error \ref MDBX_KEYEXIST with returning the first value from those already present|
-| _UPSERTING_|||
-|Key is absent → Insertion                    |\ref MDBX_UPSERT     |Insertion|
-|Key exist → Wanna to add new values          |\ref MDBX_UPSERT     |Add one more value to the key|
-|Key exist → Replace all values with a new one|\ref MDBX_UPSERT + \ref MDBX_ALLDUPS|Overwrite by single new value|
-|  _UPDATING_|||
-|Key is absent → Error since no such key      |\ref MDBX_CURRENT    |Error \ref MDBX_NOTFOUND|
-|Key exist, Single value → Update             |\ref MDBX_CURRENT    |Update single value    |
-|Key exist, Multiple values → Replace all values with a new one|\ref MDBX_CURRENT + \ref MDBX_ALLDUPS|Overwrite by single new value|
-|Key exist, Multiple values → Error since it is unclear which of the values should be updated|\ref mdbx_put() with \ref MDBX_CURRENT|Error \ref MDBX_EMULTIVAL|
-|Key exist, Multiple values → Update particular entry of multi-value|\ref mdbx_replace() with \ref MDBX_CURRENT + \ref MDBX_NOOVERWRITE and the parameter `old_value` filled with the value that wanna to update|Update one multi-value entry|
-|Key exist, Multiple values → Update the current entry of multi-value|\ref mdbx_cursor_put() with \ref MDBX_CURRENT|Update one multi-value entry|
-| _DELETING_|||
-|Key is absent → Error since no such key      |\ref mdbx_del() or \ref mdbx_replace()|Error \ref MDBX_NOTFOUND|
-|Key exist → Delete all values corresponds given key|\ref mdbx_del() with the parameter `data = NULL`|Deletion|
-|Key exist → Delete particular value corresponds given key|\ref mdbx_del() with the parameter `data` filled with the value that wanna to delete, or \ref mdbx_replace() with \ref MDBX_CURRENT + \ref MDBX_NOOVERWRITE and the `old_value` parameter filled with the value that wanna to delete and `new_data = NULL`| Deletion or \ref MDBX_NOTFOUND if no such key-value pair|
-|Delete one value at the current cursor position|\ref mdbx_cursor_del() with \ref MDBX_CURRENT flag|Deletion only the current entry|
-|Delete all values of key at the current cursor position|\ref mdbx_cursor_del() with with \ref MDBX_ALLDUPS flag|Deletion all duplicates of key (all multi-values) at the current cursor position|
-
- \defgroup c_cursors Cursors
- \defgroup c_statinfo Statistics & Information
- \defgroup c_settings Settings
- \defgroup c_debug Logging and runtime debug
- \defgroup c_rqest Range query estimation
- \defgroup c_extra Extra operations
-*/
-
-/* *INDENT-ON* */
-/* clang-format on */
-
-#include <stdarg.h>
-#include <stddef.h>
-#include <stdint.h>
-
-#if defined(_WIN32) || defined(_WIN64)
-#include <windows.h>
-#include <winnt.h>
-#ifndef __mode_t_defined
-typedef unsigned short mdbx_mode_t;
-#else
-typedef mode_t mdbx_mode_t;
-#endif /* __mode_t_defined */
-typedef HANDLE mdbx_filehandle_t;
-typedef DWORD mdbx_pid_t;
-typedef DWORD mdbx_tid_t;
-#else                  /* Windows */
-#include <errno.h>     /* for error codes */
-#include <pthread.h>   /* for pthread_t */
-#include <sys/types.h> /* for pid_t */
-#include <sys/uio.h>   /* for struct iovec */
-#define HAVE_STRUCT_IOVEC 1
-typedef int mdbx_filehandle_t;
-typedef pid_t mdbx_pid_t;
-typedef pthread_t mdbx_tid_t;
-typedef mode_t mdbx_mode_t;
-#endif /* !Windows */
-
-#ifdef _MSC_VER
-#pragma warning(pop)
-#endif
-
-/** @} close c_api
- * \defgroup api_macros Common Macros
- * @{ */
-
-/*----------------------------------------------------------------------------*/
-
-#ifndef __has_attribute
-#define __has_attribute(x) (0)
-#endif /* __has_attribute */
-
-#ifndef __has_cpp_attribute
-#define __has_cpp_attribute(x) 0
-#endif /* __has_cpp_attribute */
-
-#ifndef __has_feature
-#define __has_feature(x) (0)
-#endif /* __has_feature */
-
-#ifndef __has_extension
-#define __has_extension(x) (0)
-#endif /* __has_extension */
-
-#ifndef __has_builtin
-#define __has_builtin(x) (0)
-#endif /* __has_builtin */
-
-/** Many functions have no effects except the return value and their
- * return value depends only on the parameters and/or global variables.
- * Such a function can be subject to common subexpression elimination
- * and loop optimization just as an arithmetic operator would be.
- * These functions should be declared with the attribute pure. */
-#if (defined(__GNUC__) || __has_attribute(__pure__)) &&                        \
-    (!defined(__clang__) /* https://bugs.llvm.org/show_bug.cgi?id=43275 */     \
-     || !defined(__cplusplus) || !__has_feature(cxx_exceptions))
-#define MDBX_PURE_FUNCTION __attribute__((__pure__))
-#elif defined(_MSC_VER) && !defined(__clang__) && _MSC_VER >= 1920
-#define MDBX_PURE_FUNCTION
-#elif defined(__cplusplus) && __has_cpp_attribute(gnu::pure) &&                \
-    (!defined(__clang__) || !__has_feature(cxx_exceptions))
-#define MDBX_PURE_FUNCTION [[gnu::pure]]
-#else
-#define MDBX_PURE_FUNCTION
-#endif /* MDBX_PURE_FUNCTION */
-
-/** Like \ref MDBX_PURE_FUNCTION with addition `noexcept` restriction
- * that is compatible to CLANG and proposed [[pure]]. */
-#if defined(__GNUC__) ||                                                       \
-    (__has_attribute(__pure__) && __has_attribute(__nothrow__))
-#define MDBX_NOTHROW_PURE_FUNCTION __attribute__((__pure__, __nothrow__))
-#elif defined(_MSC_VER) && !defined(__clang__) && _MSC_VER >= 1920
-#if __has_cpp_attribute(pure)
-#define MDBX_NOTHROW_PURE_FUNCTION [[pure]]
-#else
-#define MDBX_NOTHROW_PURE_FUNCTION
-#endif
-#elif defined(__cplusplus) && __has_cpp_attribute(gnu::pure)
-#if __has_cpp_attribute(gnu::nothrow)
-#define MDBX_NOTHROW_PURE_FUNCTION [[gnu::pure, gnu::nothrow]]
-#else
-#define MDBX_NOTHROW_PURE_FUNCTION [[gnu::pure]]
-#endif
-#elif defined(__cplusplus) && __has_cpp_attribute(pure)
-#define MDBX_NOTHROW_PURE_FUNCTION [[pure]]
-#else
-#define MDBX_NOTHROW_PURE_FUNCTION
-#endif /* MDBX_NOTHROW_PURE_FUNCTION */
-
-/** Many functions do not examine any values except their arguments,
- * and have no effects except the return value. Basically this is just
- * slightly more strict class than the PURE attribute, since function
- * is not allowed to read global memory.
- *
- * Note that a function that has pointer arguments and examines the
- * data pointed to must not be declared const. Likewise, a function
- * that calls a non-const function usually must not be const.
- * It does not make sense for a const function to return void. */
-#if (defined(__GNUC__) || __has_attribute(__pure__)) &&                        \
-    (!defined(__clang__) /* https://bugs.llvm.org/show_bug.cgi?id=43275 */     \
-     || !defined(__cplusplus) || !__has_feature(cxx_exceptions))
-#define MDBX_CONST_FUNCTION __attribute__((__const__))
-#elif defined(_MSC_VER) && !defined(__clang__) && _MSC_VER >= 1920
-#define MDBX_CONST_FUNCTION MDBX_PURE_FUNCTION
-#elif defined(__cplusplus) && __has_cpp_attribute(gnu::const) &&               \
-    (!defined(__clang__) || !__has_feature(cxx_exceptions))
-#define MDBX_CONST_FUNCTION [[gnu::const]]
-#else
-#define MDBX_CONST_FUNCTION MDBX_PURE_FUNCTION
-#endif /* MDBX_CONST_FUNCTION */
-
-/** Like \ref MDBX_CONST_FUNCTION with addition `noexcept` restriction
- * that is compatible to CLANG and future [[const]]. */
-#if defined(__GNUC__) ||                                                       \
-    (__has_attribute(__const__) && __has_attribute(__nothrow__))
-#define MDBX_NOTHROW_CONST_FUNCTION __attribute__((__const__, __nothrow__))
-#elif defined(_MSC_VER) && !defined(__clang__) && _MSC_VER >= 1920
-#define MDBX_NOTHROW_CONST_FUNCTION MDBX_NOTHROW_PURE_FUNCTION
-#elif defined(__cplusplus) && __has_cpp_attribute(gnu::const)
-#if __has_cpp_attribute(gnu::nothrow)
-#define MDBX_NOTHROW_PURE_FUNCTION [[gnu::const, gnu::nothrow]]
-#else
-#define MDBX_NOTHROW_PURE_FUNCTION [[gnu::const]]
-#endif
-#elif defined(__cplusplus) && __has_cpp_attribute(const)
-#define MDBX_NOTHROW_CONST_FUNCTION [[const]]
-#else
-#define MDBX_NOTHROW_CONST_FUNCTION MDBX_NOTHROW_PURE_FUNCTION
-#endif /* MDBX_NOTHROW_CONST_FUNCTION */
-
-#ifndef MDBX_DEPRECATED /* may be predefined to avoid warnings "deprecated" */
-#ifdef __deprecated
-#define MDBX_DEPRECATED __deprecated
-#elif defined(__GNUC__) || __has_attribute(__deprecated__)
-#define MDBX_DEPRECATED __attribute__((__deprecated__))
-#elif defined(_MSC_VER)
-#define MDBX_DEPRECATED __declspec(deprecated)
-#else
-#define MDBX_DEPRECATED
-#endif
-#endif /* MDBX_DEPRECATED */
-
-#ifndef __dll_export
-#if defined(_WIN32) || defined(__CYGWIN__)
-#if defined(__GNUC__) || __has_attribute(__dllexport__)
-#define __dll_export __attribute__((__dllexport__))
-#elif defined(_MSC_VER)
-#define __dll_export __declspec(dllexport)
-#else
-#define __dll_export
-#endif
-#elif defined(__GNUC__) || __has_attribute(__visibility__)
-#define __dll_export __attribute__((__visibility__("default")))
-#else
-#define __dll_export
-#endif
-#endif /* __dll_export */
-
-#ifndef __dll_import
-#if defined(_WIN32) || defined(__CYGWIN__)
-#if defined(__GNUC__) || __has_attribute(__dllimport__)
-#define __dll_import __attribute__((__dllimport__))
-#elif defined(_MSC_VER)
-#define __dll_import __declspec(dllimport)
-#else
-#define __dll_import
-#endif
-#else
-#define __dll_import
-#endif
-#endif /* __dll_import */
-
-/** \brief Auxiliary macro for robustly define the both inline version of API
- * function and non-inline fallback dll-exported version for applications linked
- * with old version of libmdbx, with a strictly ODR-common implementation. */
-#if !defined(LIBMDBX_INTERNALS)
-#define LIBMDBX_INLINE_API(TYPE, NAME, ARGS) static __inline TYPE NAME ARGS
-#else
-#define LIBMDBX_INLINE_API(TYPE, NAME, ARGS)                                   \
-  /* proto of exported which uses common impl */ LIBMDBX_API TYPE NAME ARGS;   \
-  /* definition of common impl */ static __inline TYPE __inline_##NAME ARGS
-#endif /* LIBMDBX_INLINE_API */
-
-/*----------------------------------------------------------------------------*/
-
-#ifndef __cplusplus
-#ifndef bool
-#define bool _Bool
-#endif
-#ifndef true
-#define true (1)
-#endif
-#ifndef false
-#define false (0)
-#endif
-#endif /* bool without __cplusplus */
-
-#if !defined(DOXYGEN) && (!defined(__cpp_noexcept_function_type) ||            \
-                          __cpp_noexcept_function_type < 201510L)
-#define MDBX_CXX17_NOEXCEPT
-#else
-#define MDBX_CXX17_NOEXCEPT noexcept
-#endif /* MDBX_CXX17_NOEXCEPT */
-
-/* Workaround for old compilers without properly support for constexpr. */
-#if !defined(__cplusplus)
-#define MDBX_CXX01_CONSTEXPR __inline
-#define MDBX_CXX01_CONSTEXPR_VAR const
-#elif !defined(DOXYGEN) &&                                                     \
-    (!defined(__cpp_constexpr) || __cpp_constexpr < 200704L ||                 \
-     (defined(__LCC__) && __LCC__ < 124) ||                                    \
-     (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 407) &&          \
-      !defined(__clang__) && !defined(__LCC__)) ||                             \
-     (defined(_MSC_VER) && _MSC_VER < 1910) ||                                 \
-     (defined(__clang__) && __clang_major__ < 4))
-#define MDBX_CXX01_CONSTEXPR inline
-#define MDBX_CXX01_CONSTEXPR_VAR const
-#else
-#define MDBX_CXX01_CONSTEXPR constexpr
-#define MDBX_CXX01_CONSTEXPR_VAR constexpr
-#endif /* MDBX_CXX01_CONSTEXPR */
-
-#if !defined(__cplusplus)
-#define MDBX_CXX11_CONSTEXPR __inline
-#define MDBX_CXX11_CONSTEXPR_VAR const
-#elif !defined(DOXYGEN) &&                                                     \
-    (!defined(__cpp_constexpr) || __cpp_constexpr < 201304 ||                  \
-     (defined(__LCC__) && __LCC__ < 124) ||                                    \
-     (defined(__GNUC__) && __GNUC__ < 6 && !defined(__clang__) &&              \
-      !defined(__LCC__)) ||                                                    \
-     (defined(_MSC_VER) && _MSC_VER < 1910) ||                                 \
-     (defined(__clang__) && __clang_major__ < 5))
-#define MDBX_CXX11_CONSTEXPR inline
-#define MDBX_CXX11_CONSTEXPR_VAR const
-#else
-#define MDBX_CXX11_CONSTEXPR constexpr
-#define MDBX_CXX11_CONSTEXPR_VAR constexpr
-#endif /* MDBX_CXX11_CONSTEXPR */
-
-#if !defined(__cplusplus)
-#define MDBX_CXX14_CONSTEXPR __inline
-#define MDBX_CXX14_CONSTEXPR_VAR const
-#elif defined(DOXYGEN) ||                                                      \
-    defined(__cpp_constexpr) && __cpp_constexpr >= 201304L &&                  \
-        ((defined(_MSC_VER) && _MSC_VER >= 1910) ||                            \
-         (defined(__clang__) && __clang_major__ > 4) ||                        \
-         (defined(__GNUC__) && __GNUC__ > 6) ||                                \
-         (!defined(__GNUC__) && !defined(__clang__) && !defined(_MSC_VER)))
-#define MDBX_CXX14_CONSTEXPR constexpr
-#define MDBX_CXX14_CONSTEXPR_VAR constexpr
-#else
-#define MDBX_CXX14_CONSTEXPR inline
-#define MDBX_CXX14_CONSTEXPR_VAR const
-#endif /* MDBX_CXX14_CONSTEXPR */
-
-#if defined(__noreturn)
-#define MDBX_NORETURN __noreturn
-#elif defined(_Noreturn)
-#define MDBX_NORETURN _Noreturn
-#elif defined(__GNUC__) || __has_attribute(__noreturn__)
-#define MDBX_NORETURN __attribute__((__noreturn__))
-#elif defined(_MSC_VER) && !defined(__clang__)
-#define MDBX_NORETURN __declspec(noreturn)
-#else
-#define MDBX_NORETURN
-#endif /* MDBX_NORETURN */
-
-#ifndef MDBX_PRINTF_ARGS
-#if defined(__GNUC__) || __has_attribute(__format__)
-#define MDBX_PRINTF_ARGS(format_index, first_arg)                              \
-  __attribute__((__format__(__printf__, format_index, first_arg)))
-#else
-#define MDBX_PRINTF_ARGS(format_index, first_arg)
-#endif
-#endif /* MDBX_PRINTF_ARGS */
-
-/* Oh, below are some songs and dances since:
- *  - C++ requires explicit definition of the necessary operators.
- *  - the proper implementation of DEFINE_ENUM_FLAG_OPERATORS for C++ required
- *    the constexpr feature which is broken in most old compilers;
- *  - DEFINE_ENUM_FLAG_OPERATORS may be defined broken as in the Windows SDK. */
-#ifndef DEFINE_ENUM_FLAG_OPERATORS
-
-#ifdef __cplusplus
-#if !defined(__cpp_constexpr) || __cpp_constexpr < 200704L ||                  \
-    (defined(__LCC__) && __LCC__ < 124) ||                                     \
-    (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 407) &&           \
-     !defined(__clang__) && !defined(__LCC__)) ||                              \
-    (defined(_MSC_VER) && _MSC_VER < 1910) ||                                  \
-    (defined(__clang__) && __clang_major__ < 4)
-/* The constexpr feature is not available or (may be) broken */
-#define CONSTEXPR_ENUM_FLAGS_OPERATIONS 0
-#else
-/* C always allows these operators for enums */
-#define CONSTEXPR_ENUM_FLAGS_OPERATIONS 1
-#endif /* __cpp_constexpr */
-
-/// Define operator overloads to enable bit operations on enum values that are
-/// used to define flags (based on Microsoft's DEFINE_ENUM_FLAG_OPERATORS).
-#define DEFINE_ENUM_FLAG_OPERATORS(ENUM)                                       \
-  extern "C++" {                                                               \
-  MDBX_CXX01_CONSTEXPR ENUM operator|(ENUM a, ENUM b) {                        \
-    return ENUM(unsigned(a) | unsigned(b));                                    \
-  }                                                                            \
-  MDBX_CXX14_CONSTEXPR ENUM &operator|=(ENUM &a, ENUM b) { return a = a | b; } \
-  MDBX_CXX01_CONSTEXPR ENUM operator&(ENUM a, ENUM b) {                        \
-    return ENUM(unsigned(a) & unsigned(b));                                    \
-  }                                                                            \
-  MDBX_CXX01_CONSTEXPR ENUM operator&(ENUM a, unsigned b) {                    \
-    return ENUM(unsigned(a) & b);                                              \
-  }                                                                            \
-  MDBX_CXX01_CONSTEXPR ENUM operator&(unsigned a, ENUM b) {                    \
-    return ENUM(a & unsigned(b));                                              \
-  }                                                                            \
-  MDBX_CXX14_CONSTEXPR ENUM &operator&=(ENUM &a, ENUM b) { return a = a & b; } \
-  MDBX_CXX14_CONSTEXPR ENUM &operator&=(ENUM &a, unsigned b) {                 \
-    return a = a & b;                                                          \
-  }                                                                            \
-  MDBX_CXX01_CONSTEXPR unsigned operator~(ENUM a) { return ~unsigned(a); }     \
-  MDBX_CXX01_CONSTEXPR ENUM operator^(ENUM a, ENUM b) {                        \
-    return ENUM(unsigned(a) ^ unsigned(b));                                    \
-  }                                                                            \
-  MDBX_CXX14_CONSTEXPR ENUM &operator^=(ENUM &a, ENUM b) { return a = a ^ b; } \
-  }
-#else /* __cplusplus */
-/* nope for C since it always allows these operators for enums */
-#define DEFINE_ENUM_FLAG_OPERATORS(ENUM)
-#define CONSTEXPR_ENUM_FLAGS_OPERATIONS 1
-#endif /* !__cplusplus */
-
-#elif !defined(CONSTEXPR_ENUM_FLAGS_OPERATIONS)
-
-#ifdef __cplusplus
-/* DEFINE_ENUM_FLAG_OPERATORS may be defined broken as in the Windows SDK */
-#define CONSTEXPR_ENUM_FLAGS_OPERATIONS 0
-#else
-/* C always allows these operators for enums */
-#define CONSTEXPR_ENUM_FLAGS_OPERATIONS 1
-#endif
-
-#endif /* DEFINE_ENUM_FLAG_OPERATORS */
-
-/** @} end of Common Macros */
-
-/*----------------------------------------------------------------------------*/
-
-/** \addtogroup c_api
- * @{ */
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* MDBX version 0.9.x */
-#define MDBX_VERSION_MAJOR 0
-#define MDBX_VERSION_MINOR 9
-
-#ifndef LIBMDBX_API
-#if defined(LIBMDBX_EXPORTS)
-#define LIBMDBX_API __dll_export
-#elif defined(LIBMDBX_IMPORTS)
-#define LIBMDBX_API __dll_import
-#else
-#define LIBMDBX_API
-#endif
-#endif /* LIBMDBX_API */
-
-#ifdef __cplusplus
-#if defined(__clang__) || __has_attribute(type_visibility)
-#define LIBMDBX_API_TYPE LIBMDBX_API __attribute__((type_visibility("default")))
-#else
-#define LIBMDBX_API_TYPE LIBMDBX_API
-#endif
-#else
-#define LIBMDBX_API_TYPE
-#endif /* LIBMDBX_API_TYPE */
-
-#if defined(LIBMDBX_IMPORTS)
-#define LIBMDBX_VERINFO_API __dll_import
-#else
-#define LIBMDBX_VERINFO_API __dll_export
-#endif /* LIBMDBX_VERINFO_API */
-
-/** \brief libmdbx version information */
-extern LIBMDBX_VERINFO_API const struct MDBX_version_info {
-  uint8_t major;     /**< Major version number */
-  uint8_t minor;     /**< Minor version number */
-  uint16_t release;  /**< Release number of Major.Minor */
-  uint32_t revision; /**< Revision number of Release */
-  struct {
-    const char *datetime; /**< committer date, strict ISO-8601 format */
-    const char *tree;     /**< commit hash (hexadecimal digits) */
-    const char *commit;   /**< tree hash, i.e. digest of the source code */
-    const char *describe; /**< git-describe string */
-  } git;                  /**< source information from git */
-  const char *sourcery;   /**< sourcery anchor for pinning */
-} /** \brief libmdbx version information */ mdbx_version;
-
-/** \brief libmdbx build information
- * \attention Some strings could be NULL in case no corresponding information
- *            was provided at build time (i.e. flags). */
-extern LIBMDBX_VERINFO_API const struct MDBX_build_info {
-  const char *datetime; /**< build timestamp (ISO-8601 or __DATE__ __TIME__) */
-  const char *target;   /**< cpu/arch-system-config triplet */
-  const char *options;  /**< mdbx-related options */
-  const char *compiler; /**< compiler */
-  const char *flags;    /**< CFLAGS and CXXFLAGS */
-} /** \brief libmdbx build information */ mdbx_build;
-
-#if defined(_WIN32) || defined(_WIN64)
-#if !MDBX_BUILD_SHARED_LIBRARY
-
-/* MDBX internally uses global and thread local storage destructors to
- * automatically (de)initialization, releasing reader lock table slots
- * and so on.
- *
- * If MDBX builded as a DLL this is done out-of-the-box by DllEntry() function,
- * which called automatically by Windows core with passing corresponding reason
- * argument.
- *
- * Otherwise, if MDBX was builded not as a DLL, some black magic
- * may be required depending of Windows version:
- *  - Modern Windows versions, including Windows Vista and later, provides
- *    support for "TLS Directory" (e.g .CRT$XL[A-Z] sections in executable
- *    or dll file). In this case, MDBX capable of doing all automatically,
- *    and you do not need to call mdbx_dll_handler().
- *  - Obsolete versions of Windows, prior to Windows Vista, REQUIRES calling
- *    mdbx_dll_handler() manually from corresponding DllMain() or WinMain()
- *    of your DLL or application.
- *  - This behavior is under control of the MODX_CONFIG_MANUAL_TLS_CALLBACK
- *    option, which is determined by default according to the target version
- *    of Windows at build time.
- *    But you may override MODX_CONFIG_MANUAL_TLS_CALLBACK in special cases.
- *
- * Therefore, building MDBX as a DLL is recommended for all version of Windows.
- * So, if you doubt, just build MDBX as the separate DLL and don't worry. */
-
-#ifndef MDBX_CONFIG_MANUAL_TLS_CALLBACK
-#if defined(_WIN32_WINNT_VISTA) && WINVER >= _WIN32_WINNT_VISTA
-/* As described above mdbx_dll_handler() is NOT needed forWindows Vista
- * and later. */
-#define MDBX_CONFIG_MANUAL_TLS_CALLBACK 0
-#else
-/* As described above mdbx_dll_handler() IS REQUIRED for Windows versions
- * prior to Windows Vista. */
-#define MDBX_CONFIG_MANUAL_TLS_CALLBACK 1
-#endif
-#endif /* MDBX_CONFIG_MANUAL_TLS_CALLBACK */
-
-#if MDBX_CONFIG_MANUAL_TLS_CALLBACK
-void LIBMDBX_API NTAPI mdbx_dll_handler(PVOID module, DWORD reason,
-                                        PVOID reserved);
-#endif /* MDBX_CONFIG_MANUAL_TLS_CALLBACK */
-#endif /* !MDBX_BUILD_SHARED_LIBRARY */
-#endif /* Windows */
-
-/* OPACITY STRUCTURES *********************************************************/
-
-/** \brief Opaque structure for a database environment.
- * \details An environment supports multiple key-value sub-databases (aka
- * key-value spaces or tables), all residing in the same shared-memory map.
- * \see mdbx_env_create() \see mdbx_env_close() */
-#ifndef __cplusplus
-typedef struct MDBX_env MDBX_env;
-#else
-struct MDBX_env;
-#endif
-
-/** \brief Opaque structure for a transaction handle.
- * \ingroup c_transactions
- * \details All database operations require a transaction handle. Transactions
- * may be read-only or read-write.
- * \see mdbx_txn_begin() \see mdbx_txn_commit() \see mdbx_txn_abort() */
-#ifndef __cplusplus
-typedef struct MDBX_txn MDBX_txn;
-#else
-struct MDBX_txn;
-#endif
-
-/** \brief A handle for an individual database (key-value spaces) in the
- * environment. \ingroup c_dbi \details Zero handle is used internally (hidden
- * Garbage Collection DB). So, any valid DBI-handle great than 0 and less than
- * or equal \ref MDBX_MAX_DBI. \see mdbx_dbi_open() \see mdbx_dbi_close() */
-typedef uint32_t MDBX_dbi;
-
-/** \brief Opaque structure for navigating through a database
- * \ingroup c_cursors
- * \see mdbx_cursor_create() \see mdbx_cursor_bind() \see mdbx_cursor_close()
- */
-#ifndef __cplusplus
-typedef struct MDBX_cursor MDBX_cursor;
-#else
-struct MDBX_cursor;
-#endif
-
-/** \brief Generic structure used for passing keys and data in and out of the
- * database.
- * \anchor MDBX_val \see mdbx::slice \see mdbx::buffer
- *
- * \details Values returned from the database are valid only until a subsequent
- * update operation, or the end of the transaction. Do not modify or
- * free them, they commonly point into the database itself.
- *
- * Key sizes must be between 0 and \ref mdbx_env_get_maxkeysize() inclusive.
- * The same applies to data sizes in databases with the \ref MDBX_DUPSORT flag.
- * Other data items can in theory be from 0 to \ref MDBX_MAXDATASIZE bytes long.
- *
- * \note The notable difference between MDBX and LMDB is that MDBX support zero
- * length keys. */
-#ifndef HAVE_STRUCT_IOVEC
-struct iovec {
-  void *iov_base; /**< pointer to some data */
-  size_t iov_len; /**< the length of data in bytes */
-};
-#define HAVE_STRUCT_IOVEC
-#endif /* HAVE_STRUCT_IOVEC */
-
-#if defined(__sun) || defined(__SVR4) || defined(__svr4__)
-/* The `iov_len` is signed on Sun/Solaris.
- * So define custom MDBX_val to avoid a lot of warnings. */
-struct MDBX_val {
-  void *iov_base; /**< pointer to some data */
-  size_t iov_len; /**< the length of data in bytes */
-};
-#ifndef __cplusplus
-typedef struct MDBX_val MDBX_val;
-#endif
-#else  /* SunOS */
-typedef struct iovec MDBX_val;
-#endif /* ! SunOS */
-
-enum MDBX_constants {
-  /** The hard limit for DBI handles */
-  MDBX_MAX_DBI = UINT32_C(32765),
-
-  /** The maximum size of a data item. */
-  MDBX_MAXDATASIZE = UINT32_C(0x7fff0000),
-
-  /** The minimal database page size in bytes. */
-  MDBX_MIN_PAGESIZE = 256,
-
-  /** The maximal database page size in bytes. */
-  MDBX_MAX_PAGESIZE = 65536,
-};
-
-/* THE FILES *******************************************************************
- * At the file system level, the environment corresponds to a pair of files. */
-
-/** \brief The name of the lock file in the environment */
-#define MDBX_LOCKNAME "/mdbx.lck"
-/** \brief The name of the data file in the environment */
-#define MDBX_DATANAME "/mdbx.dat"
-
-/** \brief The suffix of the lock file when \ref MDBX_NOSUBDIR is used */
-#define MDBX_LOCK_SUFFIX "-lck"
-
-/* DEBUG & LOGGING ************************************************************/
-
-/** \addtogroup c_debug
- * \note Most of debug feature enabled only when libmdbx builded with
- * \ref MDBX_DEBUG build option. @{ */
-
-/** Log level (requires build libmdbx with \ref MDBX_DEBUG option) */
-enum MDBX_log_level_t {
-  /** Critical conditions, i.e. assertion failures */
-  MDBX_LOG_FATAL = 0,
-
-  /** Enables logging for error conditions and \ref MDBX_LOG_FATAL */
-  MDBX_LOG_ERROR = 1,
-
-  /** Enables logging for warning conditions and \ref MDBX_LOG_ERROR ...
-      \ref MDBX_LOG_FATAL */
-  MDBX_LOG_WARN = 2,
-
-  /** Enables logging for normal but significant condition and
-      \ref MDBX_LOG_WARN ... \ref MDBX_LOG_FATAL */
-  MDBX_LOG_NOTICE = 3,
-
-  /** Enables logging for verbose informational and \ref MDBX_LOG_NOTICE ...
-      \ref MDBX_LOG_FATAL */
-  MDBX_LOG_VERBOSE = 4,
-
-  /** Enables logging for debug-level messages and \ref MDBX_LOG_VERBOSE ...
-      \ref MDBX_LOG_FATAL */
-  MDBX_LOG_DEBUG = 5,
-
-  /** Enables logging for trace debug-level messages and \ref MDBX_LOG_DEBUG ...
-      \ref MDBX_LOG_FATAL */
-  MDBX_LOG_TRACE = 6,
-
-  /** Enables extra debug-level messages (dump pgno lists)
-      and all other log-messages */
-  MDBX_LOG_EXTRA = 7,
-
-  /** for \ref mdbx_setup_debug() only: Don't change current settings */
-  MDBX_LOG_DONTCHANGE = -1
-};
-#ifndef __cplusplus
-typedef enum MDBX_log_level_t MDBX_log_level_t;
-#endif
-
-/** \brief Runtime debug flags
- *
- * \details `MDBX_DBG_DUMP` and `MDBX_DBG_LEGACY_MULTIOPEN` always have an
- * effect, but `MDBX_DBG_ASSERT`, `MDBX_DBG_AUDIT` and `MDBX_DBG_JITTER` only if
- * libmdbx builded with \ref MDBX_DEBUG. */
-enum MDBX_debug_flags_t {
-  /** Enable assertion checks.
-   * Requires build with \ref MDBX_DEBUG > 0 */
-  MDBX_DBG_ASSERT = 1,
-
-  /** Enable pages usage audit at commit transactions.
-   * Requires build with \ref MDBX_DEBUG > 0 */
-  MDBX_DBG_AUDIT = 2,
-
-  /** Enable small random delays in critical points.
-   * Requires build with \ref MDBX_DEBUG > 0 */
-  MDBX_DBG_JITTER = 4,
-
-  /** Include or not meta-pages in coredump files.
-   * May affect performance in \ref MDBX_WRITEMAP mode */
-  MDBX_DBG_DUMP = 8,
-
-  /** Allow multi-opening environment(s) */
-  MDBX_DBG_LEGACY_MULTIOPEN = 16,
-
-  /** Allow read and write transactions overlapping for the same thread */
-  MDBX_DBG_LEGACY_OVERLAP = 32,
-
-  /** for mdbx_setup_debug() only: Don't change current settings */
-  MDBX_DBG_DONTCHANGE = -1
-};
-#ifndef __cplusplus
-typedef enum MDBX_debug_flags_t MDBX_debug_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_debug_flags_t)
-#endif
-
-/** \brief A debug-logger callback function,
- * called before printing the message and aborting.
- * \see mdbx_setup_debug()
- *
- * \param [in] env  An environment handle returned by \ref mdbx_env_create().
- * \param [in] msg  The assertion message, not including newline. */
-typedef void MDBX_debug_func(MDBX_log_level_t loglevel, const char *function,
-                             int line, const char *fmt,
-                             va_list args) MDBX_CXX17_NOEXCEPT;
-
-/** \brief The "don't change `logger`" value for mdbx_setup_debug() */
-#define MDBX_LOGGER_DONTCHANGE ((MDBX_debug_func *)(intptr_t)-1)
-
-/** \brief Setup global log-level, debug options and debug logger.
- * \returns The previously `debug_flags` in the 0-15 bits
- *          and `log_level` in the 16-31 bits. */
-LIBMDBX_API int mdbx_setup_debug(MDBX_log_level_t log_level,
-                                 MDBX_debug_flags_t debug_flags,
-                                 MDBX_debug_func *logger);
-
-/** \brief A callback function for most MDBX assert() failures,
- * called before printing the message and aborting.
- * \see mdbx_env_set_assert()
- *
- * \param [in] env  An environment handle returned by mdbx_env_create().
- * \param [in] msg  The assertion message, not including newline. */
-typedef void MDBX_assert_func(const MDBX_env *env, const char *msg,
-                              const char *function,
-                              unsigned line) MDBX_CXX17_NOEXCEPT;
-
-/** \brief Set or reset the assert() callback of the environment.
- *
- * Does nothing if libmdbx was built with MDBX_DEBUG=0 or with NDEBUG,
- * and will return `MDBX_ENOSYS` in such case.
- *
- * \param [in] env   An environment handle returned by mdbx_env_create().
- * \param [in] func  An MDBX_assert_func function, or 0.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_set_assert(MDBX_env *env, MDBX_assert_func *func);
-
-/** \brief Dump given MDBX_val to the buffer
- *
- * Dumps it as string if value is printable (all bytes in the range 0x20..0x7E),
- * otherwise made hexadecimal dump. Requires at least 4 byte length buffer.
- *
- * \returns One of:
- *  - NULL if given buffer size less than 4 bytes;
- *  - pointer to constant string if given value NULL or empty;
- *  - otherwise pointer to given buffer. */
-LIBMDBX_API const char *mdbx_dump_val(const MDBX_val *key, char *const buf,
-                                      const size_t bufsize);
-
-/** \brief Panics with message and causes abnormal process termination. */
-LIBMDBX_API void mdbx_panic(const char *fmt, ...) MDBX_PRINTF_ARGS(1, 2);
-
-/** @} end of logging & debug */
-
-/** \brief Environment flags
- * \ingroup c_opening
- * \anchor env_flags
- * \see mdbx_env_open() \see mdbx_env_set_flags() */
-enum MDBX_env_flags_t {
-  MDBX_ENV_DEFAULTS = 0,
-
-  /** No environment directory.
-   *
-   * By default, MDBX creates its environment in a directory whose pathname is
-   * given in path, and creates its data and lock files under that directory.
-   * With this option, path is used as-is for the database main data file.
-   * The database lock file is the path with "-lck" appended.
-   *
-   * - with `MDBX_NOSUBDIR` = in a filesystem we have the pair of MDBX-files
-   *   which names derived from given pathname by appending predefined suffixes.
-   *
-   * - without `MDBX_NOSUBDIR` = in a filesystem we have the MDBX-directory with
-   *   given pathname, within that a pair of MDBX-files with predefined names.
-   *
-   * This flag affects only at new environment creating by \ref mdbx_env_open(),
-   * otherwise at opening an existing environment libmdbx will choice this
-   * automatically. */
-  MDBX_NOSUBDIR = UINT32_C(0x4000),
-
-  /** Read only mode.
-   *
-   * Open the environment in read-only mode. No write operations will be
-   * allowed. MDBX will still modify the lock file - except on read-only
-   * filesystems, where MDBX does not use locks.
-   *
-   * - with `MDBX_RDONLY` = open environment in read-only mode.
-   *   MDBX supports pure read-only mode (i.e. without opening LCK-file) only
-   *   when environment directory and/or both files are not writable (and the
-   *   LCK-file may be missing). In such case allowing file(s) to be placed
-   *   on a network read-only share.
-   *
-   * - without `MDBX_RDONLY` = open environment in read-write mode.
-   *
-   * This flag affects only at environment opening but can't be changed after.
-   */
-  MDBX_RDONLY = UINT32_C(0x20000),
-
-  /** Open environment in exclusive/monopolistic mode.
-   *
-   * `MDBX_EXCLUSIVE` flag can be used as a replacement for `MDB_NOLOCK`,
-   * which don't supported by MDBX.
-   * In this way, you can get the minimal overhead, but with the correct
-   * multi-process and multi-thread locking.
-   *
-   * - with `MDBX_EXCLUSIVE` = open environment in exclusive/monopolistic mode
-   *   or return \ref MDBX_BUSY if environment already used by other process.
-   *   The main feature of the exclusive mode is the ability to open the
-   *   environment placed on a network share.
-   *
-   * - without `MDBX_EXCLUSIVE` = open environment in cooperative mode,
-   *   i.e. for multi-process access/interaction/cooperation.
-   *   The main requirements of the cooperative mode are:
-   *
-   *   1. data files MUST be placed in the LOCAL file system,
-   *      but NOT on a network share.
-   *   2. environment MUST be opened only by LOCAL processes,
-   *      but NOT over a network.
-   *   3. OS kernel (i.e. file system and memory mapping implementation) and
-   *      all processes that open the given environment MUST be running
-   *      in the physically single RAM with cache-coherency. The only
-   *      exception for cache-consistency requirement is Linux on MIPS
-   *      architecture, but this case has not been tested for a long time).
-   *
-   * This flag affects only at environment opening but can't be changed after.
-   */
-  MDBX_EXCLUSIVE = UINT32_C(0x400000),
-
-  /** Using database/environment which already opened by another process(es).
-   *
-   * The `MDBX_ACCEDE` flag is useful to avoid \ref MDBX_INCOMPATIBLE error
-   * while opening the database/environment which is already used by another
-   * process(es) with unknown mode/flags. In such cases, if there is a
-   * difference in the specified flags (\ref MDBX_NOMETASYNC,
-   * \ref MDBX_SAFE_NOSYNC, \ref MDBX_UTTERLY_NOSYNC, \ref MDBX_LIFORECLAIM,
-   * \ref MDBX_COALESCE and \ref MDBX_NORDAHEAD), instead of returning an error,
-   * the database will be opened in a compatibility with the already used mode.
-   *
-   * `MDBX_ACCEDE` has no effect if the current process is the only one either
-   * opening the DB in read-only mode or other process(es) uses the DB in
-   * read-only mode. */
-  MDBX_ACCEDE = UINT32_C(0x40000000),
-
-  /** Map data into memory with write permission.
-   *
-   * Use a writeable memory map unless \ref MDBX_RDONLY is set. This uses fewer
-   * mallocs and requires much less work for tracking database pages, but
-   * loses protection from application bugs like wild pointer writes and other
-   * bad updates into the database. This may be slightly faster for DBs that
-   * fit entirely in RAM, but is slower for DBs larger than RAM. Also adds the
-   * possibility for stray application writes thru pointers to silently
-   * corrupt the database.
-   *
-   * - with `MDBX_WRITEMAP` = all data will be mapped into memory in the
-   *   read-write mode. This offers a significant performance benefit, since the
-   *   data will be modified directly in mapped memory and then flushed to disk
-   *   by single system call, without any memory management nor copying.
-   *
-   * - without `MDBX_WRITEMAP` = data will be mapped into memory in the
-   *   read-only mode. This requires stocking all modified database pages in
-   *   memory and then writing them to disk through file operations.
-   *
-   * \warning On the other hand, `MDBX_WRITEMAP` adds the possibility for stray
-   * application writes thru pointers to silently corrupt the database.
-   *
-   * \note The `MDBX_WRITEMAP` mode is incompatible with nested transactions,
-   * since this is unreasonable. I.e. nested transactions requires mallocation
-   * of database pages and more work for tracking ones, which neuters a
-   * performance boost caused by the `MDBX_WRITEMAP` mode.
-   *
-   * This flag affects only at environment opening but can't be changed after.
-   */
-  MDBX_WRITEMAP = UINT32_C(0x80000),
-
-  /** Tie reader locktable slots to read-only transactions
-   * instead of to threads.
-   *
-   * Don't use Thread-Local Storage, instead tie reader locktable slots to
-   * \ref MDBX_txn objects instead of to threads. So, \ref mdbx_txn_reset()
-   * keeps the slot reserved for the \ref MDBX_txn object. A thread may use
-   * parallel read-only transactions. And a read-only transaction may span
-   * threads if you synchronizes its use.
-   *
-   * Applications that multiplex many user threads over individual OS threads
-   * need this option. Such an application must also serialize the write
-   * transactions in an OS thread, since MDBX's write locking is unaware of
-   * the user threads.
-   *
-   * \note Regardless to `MDBX_NOTLS` flag a write transaction entirely should
-   * always be used in one thread from start to finish. MDBX checks this in a
-   * reasonable manner and return the \ref MDBX_THREAD_MISMATCH error in rules
-   * violation.
-   *
-   * This flag affects only at environment opening but can't be changed after.
-   */
-  MDBX_NOTLS = UINT32_C(0x200000),
-
-  /** Don't do readahead.
-   *
-   * Turn off readahead. Most operating systems perform readahead on read
-   * requests by default. This option turns it off if the OS supports it.
-   * Turning it off may help random read performance when the DB is larger
-   * than RAM and system RAM is full.
-   *
-   * By default libmdbx dynamically enables/disables readahead depending on
-   * the actual database size and currently available memory. On the other
-   * hand, such automation has some limitation, i.e. could be performed only
-   * when DB size changing but can't tracks and reacts changing a free RAM
-   * availability, since it changes independently and asynchronously.
-   *
-   * \note The mdbx_is_readahead_reasonable() function allows to quickly find
-   * out whether to use readahead or not based on the size of the data and the
-   * amount of available memory.
-   *
-   * This flag affects only at environment opening and can't be changed after.
-   */
-  MDBX_NORDAHEAD = UINT32_C(0x800000),
-
-  /** Don't initialize malloc'd memory before writing to datafile.
-   *
-   * Don't initialize malloc'd memory before writing to unused spaces in the
-   * data file. By default, memory for pages written to the data file is
-   * obtained using malloc. While these pages may be reused in subsequent
-   * transactions, freshly malloc'd pages will be initialized to zeroes before
-   * use. This avoids persisting leftover data from other code (that used the
-   * heap and subsequently freed the memory) into the data file.
-   *
-   * Note that many other system libraries may allocate and free memory from
-   * the heap for arbitrary uses. E.g., stdio may use the heap for file I/O
-   * buffers. This initialization step has a modest performance cost so some
-   * applications may want to disable it using this flag. This option can be a
-   * problem for applications which handle sensitive data like passwords, and
-   * it makes memory checkers like Valgrind noisy. This flag is not needed
-   * with \ref MDBX_WRITEMAP, which writes directly to the mmap instead of using
-   * malloc for pages. The initialization is also skipped if \ref MDBX_RESERVE
-   * is used; the caller is expected to overwrite all of the memory that was
-   * reserved in that case.
-   *
-   * This flag may be changed at any time using `mdbx_env_set_flags()`. */
-  MDBX_NOMEMINIT = UINT32_C(0x1000000),
-
-  /** Aims to coalesce a Garbage Collection items.
-   *
-   * With `MDBX_COALESCE` flag MDBX will aims to coalesce items while recycling
-   * a Garbage Collection. Technically, when possible short lists of pages
-   * will be combined into longer ones, but to fit on one database page. As a
-   * result, there will be fewer items in Garbage Collection and a page lists
-   * are longer, which slightly increases the likelihood of returning pages to
-   * Unallocated space and reducing the database file.
-   *
-   * This flag may be changed at any time using mdbx_env_set_flags(). */
-  MDBX_COALESCE = UINT32_C(0x2000000),
-
-  /** LIFO policy for recycling a Garbage Collection items.
-   *
-   * `MDBX_LIFORECLAIM` flag turns on LIFO policy for recycling a Garbage
-   * Collection items, instead of FIFO by default. On systems with a disk
-   * write-back cache, this can significantly increase write performance, up
-   * to several times in a best case scenario.
-   *
-   * LIFO recycling policy means that for reuse pages will be taken which became
-   * unused the lastest (i.e. just now or most recently). Therefore the loop of
-   * database pages circulation becomes as short as possible. In other words,
-   * the number of pages, that are overwritten in memory and on disk during a
-   * series of write transactions, will be as small as possible. Thus creates
-   * ideal conditions for the efficient operation of the disk write-back cache.
-   *
-   * \ref MDBX_LIFORECLAIM is compatible with all no-sync flags, but gives NO
-   * noticeable impact in combination with \ref MDBX_SAFE_NOSYNC or
-   * \ref MDBX_UTTERLY_NOSYNC. Because MDBX will reused pages only before the
-   * last "steady" MVCC-snapshot, i.e. the loop length of database pages
-   * circulation will be mostly defined by frequency of calling
-   * \ref mdbx_env_sync() rather than LIFO and FIFO difference.
-   *
-   * This flag may be changed at any time using mdbx_env_set_flags(). */
-  MDBX_LIFORECLAIM = UINT32_C(0x4000000),
-
-  /** Debugging option, fill/perturb released pages. */
-  MDBX_PAGEPERTURB = UINT32_C(0x8000000),
-
-  /* SYNC MODES****************************************************************/
-  /** \defgroup sync_modes SYNC MODES
-   *
-   * \attention Using any combination of \ref MDBX_SAFE_NOSYNC, \ref
-   * MDBX_NOMETASYNC and especially \ref MDBX_UTTERLY_NOSYNC is always a deal to
-   * reduce durability for gain write performance. You must know exactly what
-   * you are doing and what risks you are taking!
-   *
-   * \note for LMDB users: \ref MDBX_SAFE_NOSYNC is NOT similar to LMDB_NOSYNC,
-   * but \ref MDBX_UTTERLY_NOSYNC is exactly match LMDB_NOSYNC. See details
-   * below.
-   *
-   * THE SCENE:
-   * - The DAT-file contains several MVCC-snapshots of B-tree at same time,
-   *   each of those B-tree has its own root page.
-   * - Each of meta pages at the beginning of the DAT file contains a
-   *   pointer to the root page of B-tree which is the result of the particular
-   *   transaction, and a number of this transaction.
-   * - For data durability, MDBX must first write all MVCC-snapshot data
-   *   pages and ensure that are written to the disk, then update a meta page
-   *   with the new transaction number and a pointer to the corresponding new
-   *   root page, and flush any buffers yet again.
-   * - Thus during commit a I/O buffers should be flushed to the disk twice;
-   *   i.e. fdatasync(), FlushFileBuffers() or similar syscall should be
-   *   called twice for each commit. This is very expensive for performance,
-   *   but guaranteed durability even on unexpected system failure or power
-   *   outage. Of course, provided that the operating system and the
-   *   underlying hardware (e.g. disk) work correctly.
-   *
-   * TRADE-OFF:
-   * By skipping some stages described above, you can significantly benefit in
-   * speed, while partially or completely losing in the guarantee of data
-   * durability and/or consistency in the event of system or power failure.
-   * Moreover, if for any reason disk write order is not preserved, then at
-   * moment of a system crash, a meta-page with a pointer to the new B-tree may
-   * be written to disk, while the itself B-tree not yet. In that case, the
-   * database will be corrupted!
-   *
-   * \see MDBX_SYNC_DURABLE \see MDBX_NOMETASYNC \see MDBX_SAFE_NOSYNC
-   * \see MDBX_UTTERLY_NOSYNC
-   *
-   * @{ */
-
-  /** Default robust and durable sync mode.
-   *
-   * Metadata is written and flushed to disk after a data is written and
-   * flushed, which guarantees the integrity of the database in the event
-   * of a crash at any time.
-   *
-   * \attention Please do not use other modes until you have studied all the
-   * details and are sure. Otherwise, you may lose your users' data, as happens
-   * in [Miranda NG](https://www.miranda-ng.org/) messenger. */
-  MDBX_SYNC_DURABLE = 0,
-
-  /** Don't sync the meta-page after commit.
-   *
-   * Flush system buffers to disk only once per transaction commit, omit the
-   * metadata flush. Defer that until the system flushes files to disk,
-   * or next non-\ref MDBX_RDONLY commit or \ref mdbx_env_sync(). Depending on
-   * the platform and hardware, with \ref MDBX_NOMETASYNC you may get a doubling
-   * of write performance.
-   *
-   * This trade-off maintains database integrity, but a system crash may
-   * undo the last committed transaction. I.e. it preserves the ACI
-   * (atomicity, consistency, isolation) but not D (durability) database
-   * property.
-   *
-   * `MDBX_NOMETASYNC` flag may be changed at any time using
-   * \ref mdbx_env_set_flags() or by passing to \ref mdbx_txn_begin() for
-   * particular write transaction. \see sync_modes */
-  MDBX_NOMETASYNC = UINT32_C(0x40000),
-
-  /** Don't sync anything but keep previous steady commits.
-   *
-   * Like \ref MDBX_UTTERLY_NOSYNC the `MDBX_SAFE_NOSYNC` flag disable similarly
-   * flush system buffers to disk when committing a transaction. But there is a
-   * huge difference in how are recycled the MVCC snapshots corresponding to
-   * previous "steady" transactions (see below).
-   *
-   * With \ref MDBX_WRITEMAP the `MDBX_SAFE_NOSYNC` instructs MDBX to use
-   * asynchronous mmap-flushes to disk. Asynchronous mmap-flushes means that
-   * actually all writes will scheduled and performed by operation system on it
-   * own manner, i.e. unordered. MDBX itself just notify operating system that
-   * it would be nice to write data to disk, but no more.
-   *
-   * Depending on the platform and hardware, with `MDBX_SAFE_NOSYNC` you may get
-   * a multiple increase of write performance, even 10 times or more.
-   *
-   * In contrast to \ref MDBX_UTTERLY_NOSYNC mode, with `MDBX_SAFE_NOSYNC` flag
-   * MDBX will keeps untouched pages within B-tree of the last transaction
-   * "steady" which was synced to disk completely. This has big implications for
-   * both data durability and (unfortunately) performance:
-   *  - a system crash can't corrupt the database, but you will lose the last
-   *    transactions; because MDBX will rollback to last steady commit since it
-   *    kept explicitly.
-   *  - the last steady transaction makes an effect similar to "long-lived" read
-   *    transaction (see above in the \ref restrictions section) since prevents
-   *    reuse of pages freed by newer write transactions, thus the any data
-   *    changes will be placed in newly allocated pages.
-   *  - to avoid rapid database growth, the system will sync data and issue
-   *    a steady commit-point to resume reuse pages, each time there is
-   *    insufficient space and before increasing the size of the file on disk.
-   *
-   * In other words, with `MDBX_SAFE_NOSYNC` flag MDBX insures you from the
-   * whole database corruption, at the cost increasing database size and/or
-   * number of disk IOPs. So, `MDBX_SAFE_NOSYNC` flag could be used with
-   * \ref mdbx_env_sync() as alternatively for batch committing or nested
-   * transaction (in some cases). As well, auto-sync feature exposed by
-   * \ref mdbx_env_set_syncbytes() and \ref mdbx_env_set_syncperiod() functions
-   * could be very useful with `MDBX_SAFE_NOSYNC` flag.
-   *
-   * The number and volume of of disk IOPs with MDBX_SAFE_NOSYNC flag will
-   * exactly the as without any no-sync flags. However, you should expect a
-   * larger process's [work set](https://bit.ly/2kA2tFX) and significantly worse
-   * a [locality of reference](https://bit.ly/2mbYq2J), due to the more
-   * intensive allocation of previously unused pages and increase the size of
-   * the database.
-   *
-   * `MDBX_SAFE_NOSYNC` flag may be changed at any time using
-   * \ref mdbx_env_set_flags() or by passing to \ref mdbx_txn_begin() for
-   * particular write transaction. */
-  MDBX_SAFE_NOSYNC = UINT32_C(0x10000),
-
-  /** \deprecated Please use \ref MDBX_SAFE_NOSYNC instead of `MDBX_MAPASYNC`.
-   *
-   * Since version 0.9.x the `MDBX_MAPASYNC` is deprecated and has the same
-   * effect as \ref MDBX_SAFE_NOSYNC with \ref MDBX_WRITEMAP. This just API
-   * simplification is for convenience and clarity. */
-  MDBX_MAPASYNC = MDBX_SAFE_NOSYNC,
-
-  /** Don't sync anything and wipe previous steady commits.
-   *
-   * Don't flush system buffers to disk when committing a transaction. This
-   * optimization means a system crash can corrupt the database, if buffers are
-   * not yet flushed to disk. Depending on the platform and hardware, with
-   * `MDBX_UTTERLY_NOSYNC` you may get a multiple increase of write performance,
-   * even 100 times or more.
-   *
-   * If the filesystem preserves write order (which is rare and never provided
-   * unless explicitly noted) and the \ref MDBX_WRITEMAP and \ref
-   * MDBX_LIFORECLAIM flags are not used, then a system crash can't corrupt the
-   * database, but you can lose the last transactions, if at least one buffer is
-   * not yet flushed to disk. The risk is governed by how often the system
-   * flushes dirty buffers to disk and how often \ref mdbx_env_sync() is called.
-   * So, transactions exhibit ACI (atomicity, consistency, isolation) properties
-   * and only lose `D` (durability). I.e. database integrity is maintained, but
-   * a system crash may undo the final transactions.
-   *
-   * Otherwise, if the filesystem not preserves write order (which is
-   * typically) or \ref MDBX_WRITEMAP or \ref MDBX_LIFORECLAIM flags are used,
-   * you should expect the corrupted database after a system crash.
-   *
-   * So, most important thing about `MDBX_UTTERLY_NOSYNC`:
-   *  - a system crash immediately after commit the write transaction
-   *    high likely lead to database corruption.
-   *  - successful completion of mdbx_env_sync(force = true) after one or
-   *    more committed transactions guarantees consistency and durability.
-   *  - BUT by committing two or more transactions you back database into
-   *    a weak state, in which a system crash may lead to database corruption!
-   *    In case single transaction after mdbx_env_sync, you may lose transaction
-   *    itself, but not a whole database.
-   *
-   * Nevertheless, `MDBX_UTTERLY_NOSYNC` provides "weak" durability in case
-   * of an application crash (but no durability on system failure), and
-   * therefore may be very useful in scenarios where data durability is
-   * not required over a system failure (e.g for short-lived data), or if you
-   * can take such risk.
-   *
-   * `MDBX_UTTERLY_NOSYNC` flag may be changed at any time using
-   * \ref mdbx_env_set_flags(), but don't has effect if passed to
-   * \ref mdbx_txn_begin() for particular write transaction. \see sync_modes */
-  MDBX_UTTERLY_NOSYNC = MDBX_SAFE_NOSYNC | UINT32_C(0x100000),
-
-  /** @} end of SYNC MODES */
-};
-#ifndef __cplusplus
-/** \ingroup c_opening */
-typedef enum MDBX_env_flags_t MDBX_env_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_env_flags_t)
-#endif
-
-/** Transaction flags
- * \ingroup c_transactions
- * \anchor txn_flags
- * \see mdbx_txn_begin() \see mdbx_txn_flags() */
-enum MDBX_txn_flags_t {
-  /** Start read-write transaction.
-   *
-   * Only one write transaction may be active at a time. Writes are fully
-   * serialized, which guarantees that writers can never deadlock. */
-  MDBX_TXN_READWRITE = 0,
-
-  /** Start read-only transaction.
-   *
-   * There can be multiple read-only transactions simultaneously that do not
-   * block each other and a write transactions. */
-  MDBX_TXN_RDONLY = MDBX_RDONLY,
-
-/** Prepare but not start read-only transaction.
- *
- * Transaction will not be started immediately, but created transaction handle
- * will be ready for use with \ref mdbx_txn_renew(). This flag allows to
- * preallocate memory and assign a reader slot, thus avoiding these operations
- * at the next start of the transaction. */
-#if CONSTEXPR_ENUM_FLAGS_OPERATIONS || defined(DOXYGEN)
-  MDBX_TXN_RDONLY_PREPARE = MDBX_RDONLY | MDBX_NOMEMINIT,
-#else
-  MDBX_TXN_RDONLY_PREPARE = uint32_t(MDBX_RDONLY) | uint32_t(MDBX_NOMEMINIT),
-#endif
-
-  /** Do not block when starting a write transaction. */
-  MDBX_TXN_TRY = UINT32_C(0x10000000),
-
-  /** Exactly the same as \ref MDBX_NOMETASYNC,
-   * but for this transaction only */
-  MDBX_TXN_NOMETASYNC = MDBX_NOMETASYNC,
-
-  /** Exactly the same as \ref MDBX_SAFE_NOSYNC,
-   * but for this transaction only */
-  MDBX_TXN_NOSYNC = MDBX_SAFE_NOSYNC
-};
-#ifndef __cplusplus
-typedef enum MDBX_txn_flags_t MDBX_txn_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_txn_flags_t)
-#endif
-
-/** \brief Database flags
- * \ingroup c_dbi
- * \anchor db_flags
- * \see mdbx_dbi_open() */
-enum MDBX_db_flags_t {
-  MDBX_DB_DEFAULTS = 0,
-
-  /** Use reverse string keys */
-  MDBX_REVERSEKEY = UINT32_C(0x02),
-
-  /** Use sorted duplicates, i.e. allow multi-values */
-  MDBX_DUPSORT = UINT32_C(0x04),
-
-  /** Numeric keys in native byte order either uint32_t or uint64_t. The keys
-   * must all be of the same size and must be aligned while passing as
-   * arguments. */
-  MDBX_INTEGERKEY = UINT32_C(0x08),
-
-  /** With \ref MDBX_DUPSORT; sorted dup items have fixed size */
-  MDBX_DUPFIXED = UINT32_C(0x10),
-
-  /** With \ref MDBX_DUPSORT and with \ref MDBX_DUPFIXED; dups are fixed size
-   * \ref MDBX_INTEGERKEY -style integers. The data values must all be of the
-   * same size and must be aligned while passing as arguments. */
-  MDBX_INTEGERDUP = UINT32_C(0x20),
-
-  /** With \ref MDBX_DUPSORT; use reverse string comparison */
-  MDBX_REVERSEDUP = UINT32_C(0x40),
-
-  /** Create DB if not already existing */
-  MDBX_CREATE = UINT32_C(0x40000),
-
-  /** Opens an existing sub-database created with unknown flags.
-   *
-   * The `MDBX_DB_ACCEDE` flag is intend to open a existing sub-database which
-   * was created with unknown flags (\ref MDBX_REVERSEKEY, \ref MDBX_DUPSORT,
-   * \ref MDBX_INTEGERKEY, \ref MDBX_DUPFIXED, \ref MDBX_INTEGERDUP and
-   * \ref MDBX_REVERSEDUP).
-   *
-   * In such cases, instead of returning the \ref MDBX_INCOMPATIBLE error, the
-   * sub-database will be opened with flags which it was created, and then an
-   * application could determine the actual flags by \ref mdbx_dbi_flags(). */
-  MDBX_DB_ACCEDE = MDBX_ACCEDE
-};
-#ifndef __cplusplus
-/** \ingroup c_dbi */
-typedef enum MDBX_db_flags_t MDBX_db_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_db_flags_t)
-#endif
-
-/** \brief Data changing flags
- * \ingroup c_crud
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- * \see mdbx_put() \see mdbx_cursor_put() \see mdbx_replace() */
-enum MDBX_put_flags_t {
-  /** Upsertion by default (without any other flags) */
-  MDBX_UPSERT = 0,
-
-  /** For insertion: Don't write if the key already exists. */
-  MDBX_NOOVERWRITE = UINT32_C(0x10),
-
-  /** Has effect only for \ref MDBX_DUPSORT databases.
-   * For upsertion: don't write if the key-value pair already exist.
-   * For deletion: remove all values for key. */
-  MDBX_NODUPDATA = UINT32_C(0x20),
-
-  /** For upsertion: overwrite the current key/data pair.
-   * MDBX allows this flag for \ref mdbx_put() for explicit overwrite/update
-   * without insertion.
-   * For deletion: remove only single entry at the current cursor position. */
-  MDBX_CURRENT = UINT32_C(0x40),
-
-  /** Has effect only for \ref MDBX_DUPSORT databases.
-   * For deletion: remove all multi-values (aka duplicates) for given key.
-   * For upsertion: replace all multi-values for given key with a new one. */
-  MDBX_ALLDUPS = UINT32_C(0x80),
-
-  /** For upsertion: Just reserve space for data, don't copy it.
-   * Return a pointer to the reserved space. */
-  MDBX_RESERVE = UINT32_C(0x10000),
-
-  /** Data is being appended.
-   * Don't split full pages, continue on a new instead. */
-  MDBX_APPEND = UINT32_C(0x20000),
-
-  /** Has effect only for \ref MDBX_DUPSORT databases.
-   * Duplicate data is being appended.
-   * Don't split full pages, continue on a new instead. */
-  MDBX_APPENDDUP = UINT32_C(0x40000),
-
-  /** Only for \ref MDBX_DUPFIXED.
-   * Store multiple data items in one call. */
-  MDBX_MULTIPLE = UINT32_C(0x80000)
-};
-#ifndef __cplusplus
-/** \ingroup c_crud */
-typedef enum MDBX_put_flags_t MDBX_put_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_put_flags_t)
-#endif
-
-/** \brief Environment copy flags
- * \ingroup c_extra
- * \see mdbx_env_copy() \see mdbx_env_copy2fd() */
-enum MDBX_copy_flags_t {
-  MDBX_CP_DEFAULTS = 0,
-
-  /** Copy with compactification: Omit free space from copy and renumber all
-   * pages sequentially */
-  MDBX_CP_COMPACT = 1u,
-
-  /** Force to make resizeable copy, i.e. dynamic size instead of fixed */
-  MDBX_CP_FORCE_DYNAMIC_SIZE = 2u
-};
-#ifndef __cplusplus
-/** \ingroup c_extra */
-typedef enum MDBX_copy_flags_t MDBX_copy_flags_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_copy_flags_t)
-#endif
-
-/** \brief Cursor operations
- * \ingroup c_cursors
- * This is the set of all operations for retrieving data using a cursor.
- * \see mdbx_cursor_set() */
-enum MDBX_cursor_op {
-  /** Position at first key/data item */
-  MDBX_FIRST,
-
-  /** \ref MDBX_DUPSORT -only: Position at first data item of current key. */
-  MDBX_FIRST_DUP,
-
-  /** \ref MDBX_DUPSORT -only: Position at key/data pair. */
-  MDBX_GET_BOTH,
-
-  /** \ref MDBX_DUPSORT -only: Position at given key and at first data greater
-   * than or equal to specified data. */
-  MDBX_GET_BOTH_RANGE,
-
-  /** Return key/data at current cursor position */
-  MDBX_GET_CURRENT,
-
-  /** \ref MDBX_DUPFIXED -only: Return up to a page of duplicate data items
-   * from current cursor position. Move cursor to prepare
-   * for \ref MDBX_NEXT_MULTIPLE. */
-  MDBX_GET_MULTIPLE,
-
-  /** Position at last key/data item */
-  MDBX_LAST,
-
-  /** \ref MDBX_DUPSORT -only: Position at last data item of current key. */
-  MDBX_LAST_DUP,
-
-  /** Position at next data item */
-  MDBX_NEXT,
-
-  /** \ref MDBX_DUPSORT -only: Position at next data item of current key. */
-  MDBX_NEXT_DUP,
-
-  /** \ref MDBX_DUPFIXED -only: Return up to a page of duplicate data items
-   * from next cursor position. Move cursor to prepare
-   * for `MDBX_NEXT_MULTIPLE`. */
-  MDBX_NEXT_MULTIPLE,
-
-  /** Position at first data item of next key */
-  MDBX_NEXT_NODUP,
-
-  /** Position at previous data item */
-  MDBX_PREV,
-
-  /** \ref MDBX_DUPSORT -only: Position at previous data item of current key. */
-  MDBX_PREV_DUP,
-
-  /** Position at last data item of previous key */
-  MDBX_PREV_NODUP,
-
-  /** Position at specified key */
-  MDBX_SET,
-
-  /** Position at specified key, return both key and data */
-  MDBX_SET_KEY,
-
-  /** Position at first key greater than or equal to specified key. */
-  MDBX_SET_RANGE,
-
-  /** \ref MDBX_DUPFIXED -only: Position at previous page and return up to
-   * a page of duplicate data items. */
-  MDBX_PREV_MULTIPLE,
-
-  /** Position at first key-value pair greater than or equal to specified,
-   * return both key and data, and the return code depends on a exact match.
-   *
-   * For non DUPSORT-ed collections this work the same to \ref MDBX_SET_RANGE,
-   * but returns \ref MDBX_SUCCESS if key found exactly and
-   * \ref MDBX_RESULT_TRUE if greater key was found.
-   *
-   * For DUPSORT-ed a data value is taken into account for duplicates,
-   * i.e. for a pairs/tuples of a key and an each data value of duplicates.
-   * Returns \ref MDBX_SUCCESS if key-value pair found exactly and
-   * \ref MDBX_RESULT_TRUE if the next pair was returned. */
-  MDBX_SET_LOWERBOUND
-};
-#ifndef __cplusplus
-/** \ingroup c_cursors */
-typedef enum MDBX_cursor_op MDBX_cursor_op;
-#endif
-
-/** \brief Errors and return codes
- * \ingroup c_err
- *
- * BerkeleyDB uses -30800 to -30999, we'll go under them
- * \see mdbx_strerror() \see mdbx_strerror_r() \see mdbx_liberr2str() */
-enum MDBX_error_t {
-  /** Successful result */
-  MDBX_SUCCESS = 0,
-
-  /** Alias for \ref MDBX_SUCCESS */
-  MDBX_RESULT_FALSE = MDBX_SUCCESS,
-
-  /** Successful result with special meaning or a flag */
-  MDBX_RESULT_TRUE = -1,
-
-  /** key/data pair already exists */
-  MDBX_KEYEXIST = -30799,
-
-  /** The first LMDB-compatible defined error code */
-  MDBX_FIRST_LMDB_ERRCODE = MDBX_KEYEXIST,
-
-  /** key/data pair not found (EOF) */
-  MDBX_NOTFOUND = -30798,
-
-  /** Requested page not found - this usually indicates corruption */
-  MDBX_PAGE_NOTFOUND = -30797,
-
-  /** Database is corrupted (page was wrong type and so on) */
-  MDBX_CORRUPTED = -30796,
-
-  /** Environment had fatal error,
-   * i.e. update of meta page failed and so on. */
-  MDBX_PANIC = -30795,
-
-  /** DB file version mismatch with libmdbx */
-  MDBX_VERSION_MISMATCH = -30794,
-
-  /** File is not a valid MDBX file */
-  MDBX_INVALID = -30793,
-
-  /** Environment mapsize reached */
-  MDBX_MAP_FULL = -30792,
-
-  /** Environment maxdbs reached */
-  MDBX_DBS_FULL = -30791,
-
-  /** Environment maxreaders reached */
-  MDBX_READERS_FULL = -30790,
-
-  /** Transaction has too many dirty pages, i.e transaction too big */
-  MDBX_TXN_FULL = -30788,
-
-  /** Cursor stack too deep - this usually indicates corruption,
-   * i.e branch-pages loop */
-  MDBX_CURSOR_FULL = -30787,
-
-  /** Page has not enough space - internal error */
-  MDBX_PAGE_FULL = -30786,
-
-  /** Database engine was unable to extend mapping, e.g. since address space
-   * is unavailable or busy. This can mean:
-   *  - Database size extended by other process beyond to environment mapsize
-   *    and engine was unable to extend mapping while starting read
-   *    transaction. Environment should be reopened to continue.
-   *  - Engine was unable to extend mapping during write transaction
-   *    or explicit call of \ref mdbx_env_set_geometry(). */
-  MDBX_UNABLE_EXTEND_MAPSIZE = -30785,
-
-  /** Environment or database is not compatible with the requested operation
-   * or the specified flags. This can mean:
-   *  - The operation expects an \ref MDBX_DUPSORT / \ref MDBX_DUPFIXED
-   *    database.
-   *  - Opening a named DB when the unnamed DB has \ref MDBX_DUPSORT /
-   *    \ref MDBX_INTEGERKEY.
-   *  - Accessing a data record as a database, or vice versa.
-   *  - The database was dropped and recreated with different flags. */
-  MDBX_INCOMPATIBLE = -30784,
-
-  /** Invalid reuse of reader locktable slot,
-   * e.g. read-transaction already run for current thread */
-  MDBX_BAD_RSLOT = -30783,
-
-  /** Transaction is not valid for requested operation,
-   * e.g. had errored and be must aborted, has a child, or is invalid */
-  MDBX_BAD_TXN = -30782,
-
-  /** Invalid size or alignment of key or data for target database,
-   * either invalid subDB name */
-  MDBX_BAD_VALSIZE = -30781,
-
-  /** The specified DBI-handle is invalid
-   * or changed by another thread/transaction */
-  MDBX_BAD_DBI = -30780,
-
-  /** Unexpected internal error, transaction should be aborted */
-  MDBX_PROBLEM = -30779,
-
-  /** The last LMDB-compatible defined error code */
-  MDBX_LAST_LMDB_ERRCODE = MDBX_PROBLEM,
-
-  /** Another write transaction is running or environment is already used while
-   * opening with \ref MDBX_EXCLUSIVE flag */
-  MDBX_BUSY = -30778,
-
-  /** The first of MDBX-added error codes */
-  MDBX_FIRST_ADDED_ERRCODE = MDBX_BUSY,
-
-  /** The specified key has more than one associated value */
-  MDBX_EMULTIVAL = -30421,
-
-  /** Bad signature of a runtime object(s), this can mean:
-   *  - memory corruption or double-free;
-   *  - ABI version mismatch (rare case); */
-  MDBX_EBADSIGN = -30420,
-
-  /** Database should be recovered, but this could NOT be done for now
-   * since it opened in read-only mode */
-  MDBX_WANNA_RECOVERY = -30419,
-
-  /** The given key value is mismatched to the current cursor position */
-  MDBX_EKEYMISMATCH = -30418,
-
-  /** Database is too large for current system,
-   * e.g. could NOT be mapped into RAM. */
-  MDBX_TOO_LARGE = -30417,
-
-  /** A thread has attempted to use a not owned object,
-   * e.g. a transaction that started by another thread. */
-  MDBX_THREAD_MISMATCH = -30416,
-
-  /** Overlapping read and write transactions for the current thread */
-  MDBX_TXN_OVERLAPPING = -30415,
-
-  /* The last of MDBX-added error codes */
-  MDBX_LAST_ADDED_ERRCODE = MDBX_TXN_OVERLAPPING,
-
-#if defined(_WIN32) || defined(_WIN64)
-  MDBX_ENODATA = ERROR_HANDLE_EOF,
-  MDBX_EINVAL = ERROR_INVALID_PARAMETER,
-  MDBX_EACCESS = ERROR_ACCESS_DENIED,
-  MDBX_ENOMEM = ERROR_OUTOFMEMORY,
-  MDBX_EROFS = ERROR_FILE_READ_ONLY,
-  MDBX_ENOSYS = ERROR_NOT_SUPPORTED,
-  MDBX_EIO = ERROR_WRITE_FAULT,
-  MDBX_EPERM = ERROR_INVALID_FUNCTION,
-  MDBX_EINTR = ERROR_CANCELLED,
-  MDBX_ENOFILE = ERROR_FILE_NOT_FOUND,
-  MDBX_EREMOTE = ERROR_REMOTE_STORAGE_MEDIA_ERROR
-#else /* Windows */
-#ifdef ENODATA
-  MDBX_ENODATA = ENODATA,
-#else
-  MDBX_ENODATA = -1,
-#endif /* ENODATA */
-  MDBX_EINVAL = EINVAL,
-  MDBX_EACCESS = EACCES,
-  MDBX_ENOMEM = ENOMEM,
-  MDBX_EROFS = EROFS,
-  MDBX_ENOSYS = ENOSYS,
-  MDBX_EIO = EIO,
-  MDBX_EPERM = EPERM,
-  MDBX_EINTR = EINTR,
-  MDBX_ENOFILE = ENOENT,
-  MDBX_EREMOTE = ENOTBLK
-#endif /* !Windows */
-};
-#ifndef __cplusplus
-/** \ingroup c_err */
-typedef enum MDBX_error_t MDBX_error_t;
-#endif
-
-/** MDBX_MAP_RESIZED
- * \ingroup c_err
- * \deprecated Please review your code to use MDBX_UNABLE_EXTEND_MAPSIZE
- * instead. */
-MDBX_DEPRECATED static __inline int MDBX_MAP_RESIZED_is_deprecated() {
-  return MDBX_UNABLE_EXTEND_MAPSIZE;
-}
-#define MDBX_MAP_RESIZED MDBX_MAP_RESIZED_is_deprecated()
-
-/** \brief Return a string describing a given error code.
- * \ingroup c_err
- *
- * This function is a superset of the ANSI C X3.159-1989 (ANSI C) `strerror()`
- * function. If the error code is greater than or equal to 0, then the string
- * returned by the system function `strerror()` is returned. If the error code
- * is less than 0, an error string corresponding to the MDBX library error is
- * returned. See errors for a list of MDBX-specific error codes.
- *
- * `mdbx_strerror()` is NOT thread-safe because may share common internal buffer
- * for system messages. The returned string must NOT be modified by the
- * application, but MAY be modified by a subsequent call to
- * \ref mdbx_strerror(), `strerror()` and other related functions.
- * \see mdbx_strerror_r()
- *
- * \param [in] errnum  The error code.
- *
- * \returns "error message" The description of the error. */
-LIBMDBX_API const char *mdbx_strerror(int errnum);
-
-/** \brief Return a string describing a given error code.
- * \ingroup c_err
- *
- * This function is a superset of the ANSI C X3.159-1989 (ANSI C) `strerror()`
- * function. If the error code is greater than or equal to 0, then the string
- * returned by the system function `strerror()` is returned. If the error code
- * is less than 0, an error string corresponding to the MDBX library error is
- * returned. See errors for a list of MDBX-specific error codes.
- *
- * `mdbx_strerror_r()` is thread-safe since uses user-supplied buffer where
- * appropriate. The returned string must NOT be modified by the application,
- * since it may be pointer to internal constant string. However, there is no
- * restriction if the returned string points to the supplied buffer.
- * \see mdbx_strerror()
- *
- * mdbx_liberr2str() returns string describing only MDBX error numbers but NULL
- * for non-MDBX error codes. This function is thread-safe since return pointer
- * to constant non-localized strings.
- *
- * \param [in] errnum  The error code.
- * \param [in,out] buf Buffer to store the error message.
- * \param [in] buflen The size of buffer to store the message.
- *
- * \returns "error message" The description of the error. */
-LIBMDBX_API const char *mdbx_strerror_r(int errnum, char *buf, size_t buflen);
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API const char *mdbx_liberr2str(int errnum);
-
-#if defined(_WIN32) || defined(_WIN64) || defined(DOXYGEN)
-/** Bit of Windows' madness. The similar to \ref mdbx_strerror() but returns
- * Windows error-messages in the OEM-encoding for console utilities.
- * \ingroup c_err
- * \see mdbx_strerror_r_ANSI2OEM() */
-LIBMDBX_API const char *mdbx_strerror_ANSI2OEM(int errnum);
-
-/** Bit of Windows' madness. The similar to \ref mdbx_strerror_r() but returns
- * Windows error-messages in the OEM-encoding for console utilities.
- * \ingroup c_err
- * \see mdbx_strerror_ANSI2OEM() */
-LIBMDBX_API const char *mdbx_strerror_r_ANSI2OEM(int errnum, char *buf,
-                                                 size_t buflen);
-#endif /* Bit of Windows' madness */
-
-/** \brief Create an MDBX environment instance.
- * \ingroup c_opening
- *
- * This function allocates memory for a \ref MDBX_env structure. To release
- * the allocated memory and discard the handle, call \ref mdbx_env_close().
- * Before the handle may be used, it must be opened using \ref mdbx_env_open().
- *
- * Various other options may also need to be set before opening the handle,
- * e.g. \ref mdbx_env_set_geometry(), \ref mdbx_env_set_maxreaders(),
- * \ref mdbx_env_set_maxdbs(), depending on usage requirements.
- *
- * \param [out] penv  The address where the new handle will be stored.
- *
- * \returns a non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_create(MDBX_env **penv);
-
-/** \brief MDBX environment options. */
-enum MDBX_option_t {
-  /** \brief Controls the maximum number of named databases for the environment.
-   *
-   * \details By default only unnamed key-value database could used and
-   * appropriate value should set by `MDBX_opt_max_db` to using any more named
-   * subDB(s). To reduce overhead, use the minimum sufficient value. This option
-   * may only set after \ref mdbx_env_create() and before \ref mdbx_env_open().
-   *
-   * \see mdbx_env_set_maxdbs() \see mdbx_env_get_maxdbs() */
-  MDBX_opt_max_db,
-
-  /** \brief Defines the maximum number of threads/reader slots
-   * for all processes interacting with the database.
-   *
-   * \details This defines the number of slots in the lock table that is used to
-   * track readers in the the environment. The default is about 100 for 4K
-   * system page size. Starting a read-only transaction normally ties a lock
-   * table slot to the current thread until the environment closes or the thread
-   * exits. If \ref MDBX_NOTLS is in use, \ref mdbx_txn_begin() instead ties the
-   * slot to the \ref MDBX_txn object until it or the \ref MDBX_env object is
-   * destroyed. This option may only set after \ref mdbx_env_create() and before
-   * \ref mdbx_env_open(), and has an effect only when the database is opened by
-   * the first process interacts with the database.
-   *
-   * \see mdbx_env_set_maxreaders() \see mdbx_env_get_maxreaders() */
-  MDBX_opt_max_readers,
-
-  /** \brief Controls interprocess/shared threshold to force flush the data
-   * buffers to disk, if \ref MDBX_SAFE_NOSYNC is used.
-   *
-   * \see mdbx_env_set_syncbytes() \see mdbx_env_get_syncbytes() */
-  MDBX_opt_sync_bytes,
-
-  /** \brief Controls interprocess/shared relative period since the last
-   * unsteady commit to force flush the data buffers to disk,
-   * if \ref MDBX_SAFE_NOSYNC is used.
-   * \see mdbx_env_set_syncperiod() \see mdbx_env_get_syncperiod() */
-  MDBX_opt_sync_period,
-
-  /** \brief Controls the in-process limit to grow a list of reclaimed/recycled
-   * page's numbers for finding a sequence of contiguous pages for large data
-   * items.
-   *
-   * \details A long values requires allocation of contiguous database pages.
-   * To find such sequences, it may be necessary to accumulate very large lists,
-   * especially when placing very long values (more than a megabyte) in a large
-   * databases (several tens of gigabytes), which is much expensive in extreme
-   * cases. This threshold allows you to avoid such costs by allocating new
-   * pages at the end of the database (with its possible growth on disk),
-   * instead of further accumulating/reclaiming Garbage Collection records.
-   *
-   * On the other hand, too small threshold will lead to unreasonable database
-   * growth, or/and to the inability of put long values.
-   *
-   * The `MDBX_opt_rp_augment_limit` controls described limit for the current
-   * process. Default is 262144, it is usually enough for most cases. */
-  MDBX_opt_rp_augment_limit,
-
-  /** \brief Controls the in-process limit to grow a cache of dirty
-   * pages for reuse in the current transaction.
-   *
-   * \details A 'dirty page' refers to a page that has been updated in memory
-   * only, the changes to a dirty page are not yet stored on disk.
-   * To reduce overhead, it is reasonable to release not all such pages
-   * immediately, but to leave some ones in cache for reuse in the current
-   * transaction.
-   *
-   * The `MDBX_opt_loose_limit` allows you to set a limit for such cache inside
-   * the current process. Should be in the range 0..255, default is 64. */
-  MDBX_opt_loose_limit,
-
-  /** \brief Controls the in-process limit of a pre-allocated memory items
-   * for dirty pages.
-   *
-   * \details A 'dirty page' refers to a page that has been updated in memory
-   * only, the changes to a dirty page are not yet stored on disk.
-   * Without \ref MDBX_WRITEMAP dirty pages are allocated from memory and
-   * released when a transaction is committed. To reduce overhead, it is
-   * reasonable to release not all ones, but to leave some allocations in
-   * reserve for reuse in the next transaction(s).
-   *
-   * The `MDBX_opt_dp_reserve_limit` allows you to set a limit for such reserve
-   * inside the current process. Default is 1024. */
-  MDBX_opt_dp_reserve_limit,
-
-  /** \brief Controls the in-process limit of dirty pages
-   * for a write transaction.
-   *
-   * \details A 'dirty page' refers to a page that has been updated in memory
-   * only, the changes to a dirty page are not yet stored on disk.
-   * Without \ref MDBX_WRITEMAP dirty pages are allocated from memory and will
-   * be busy until are written to disk. Therefore for a large transactions is
-   * reasonable to limit dirty pages collecting above an some threshold but
-   * spill to disk instead.
-   *
-   * The `MDBX_opt_txn_dp_limit` controls described threshold for the current
-   * process. Default is 65536, it is usually enough for most cases. */
-  MDBX_opt_txn_dp_limit,
-
-  /** \brief Controls the in-process initial allocation size for dirty pages
-   * list of a write transaction. Default is 1024. */
-  MDBX_opt_txn_dp_initial,
-
-  /** \brief Controls the in-process how maximal part of the dirty pages may be
-   * spilled when necessary.
-   *
-   * \details The `MDBX_opt_spill_max_denominator` defines the denominator for
-   * limiting from the top for part of the current dirty pages may be spilled
-   * when the free room for a new dirty pages (i.e. distance to the
-   * `MDBX_opt_txn_dp_limit` threshold) is not enough to perform requested
-   * operation.
-   * Exactly `max_pages_to_spill = dirty_pages - dirty_pages / N`,
-   * where `N` is the value set by `MDBX_opt_spill_max_denominator`.
-   *
-   * Should be in the range 0..255, where zero means no limit, i.e. all dirty
-   * pages could be spilled. Default is 8, i.e. no more than 7/8 of the current
-   * dirty pages may be spilled when reached the condition described above. */
-  MDBX_opt_spill_max_denominator,
-
-  /** \brief Controls the in-process how minimal part of the dirty pages should
-   * be spilled when necessary.
-   *
-   * \details The `MDBX_opt_spill_min_denominator` defines the denominator for
-   * limiting from the bottom for part of the current dirty pages should be
-   * spilled when the free room for a new dirty pages (i.e. distance to the
-   * `MDBX_opt_txn_dp_limit` threshold) is not enough to perform requested
-   * operation.
-   * Exactly `min_pages_to_spill = dirty_pages / N`,
-   * where `N` is the value set by `MDBX_opt_spill_min_denominator`.
-   *
-   * Should be in the range 0..255, where zero means no restriction at the
-   * bottom. Default is 8, i.e. at least the 1/8 of the current dirty pages
-   * should be spilled when reached the condition described above. */
-  MDBX_opt_spill_min_denominator,
-
-  /** \brief Controls the in-process how much of the parent transaction dirty
-   * pages will be spilled while start each child transaction.
-   *
-   * \details The `MDBX_opt_spill_parent4child_denominator` defines the
-   * denominator to determine how much of parent transaction dirty pages will be
-   * spilled explicitly while start each child transaction.
-   * Exactly `pages_to_spill = dirty_pages / N`,
-   * where `N` is the value set by `MDBX_opt_spill_parent4child_denominator`.
-   *
-   * For a stack of nested transactions each dirty page could be spilled only
-   * once, and parent's dirty pages couldn't be spilled while child
-   * transaction(s) are running. Therefore a child transaction could reach
-   * \ref MDBX_TXN_FULL when parent(s) transaction has  spilled too less (and
-   * child reach the limit of dirty pages), either when parent(s) has spilled
-   * too more (since child can't spill already spilled pages). So there is no
-   * universal golden ratio.
-   *
-   * Should be in the range 0..255, where zero means no explicit spilling will
-   * be performed during starting nested transactions.
-   * Default is 0, i.e. by default no spilling performed during starting nested
-   * transactions, that correspond historically behaviour. */
-  MDBX_opt_spill_parent4child_denominator,
-};
-#ifndef __cplusplus
-/** \ingroup c_settings */
-typedef enum MDBX_option_t MDBX_option_t;
-#endif
-
-LIBMDBX_API int mdbx_env_set_option(MDBX_env *env, const MDBX_option_t option,
-                                    const uint64_t value);
-LIBMDBX_API int mdbx_env_get_option(const MDBX_env *env,
-                                    const MDBX_option_t option,
-                                    uint64_t *value);
-
-/** \brief Open an environment instance.
- * \ingroup c_opening
- *
- * Indifferently this function will fails or not, the \ref mdbx_env_close() must
- * be called later to discard the \ref MDBX_env handle and release associated
- * resources.
- *
- * \param [in] env       An environment handle returned
- *                       by \ref mdbx_env_create()
- *
- * \param [in] pathname  The pathname for the database or the directory in which
- *                       the database files reside. In the case of directory it
- *                       must already exist and be writable.
- *
- * \param [in] flags     Special options for this environment. This parameter
- *                       must be set to 0 or by bitwise OR'ing together one
- *                       or more of the values described above in the
- *                       \ref env_flags and \ref sync_modes sections.
- *
- * Flags set by mdbx_env_set_flags() are also used:
- *  - \ref MDBX_NOSUBDIR, \ref MDBX_RDONLY, \ref MDBX_EXCLUSIVE,
- *    \ref MDBX_WRITEMAP, \ref MDBX_NOTLS, \ref MDBX_NORDAHEAD,
- *    \ref MDBX_NOMEMINIT, \ref MDBX_COALESCE, \ref MDBX_LIFORECLAIM.
- *    See \ref env_flags section.
- *
- *  - \ref MDBX_NOMETASYNC, \ref MDBX_SAFE_NOSYNC, \ref MDBX_UTTERLY_NOSYNC.
- *    See \ref sync_modes section.
- *
- * \note `MDB_NOLOCK` flag don't supported by MDBX,
- *       try use \ref MDBX_EXCLUSIVE as a replacement.
- *
- * \note MDBX don't allow to mix processes with different \ref MDBX_SAFE_NOSYNC
- *       flags on the same environment.
- *       In such case \ref MDBX_INCOMPATIBLE will be returned.
- *
- * If the database is already exist and parameters specified early by
- * \ref mdbx_env_set_geometry() are incompatible (i.e. for instance, different
- * page size) then \ref mdbx_env_open() will return \ref MDBX_INCOMPATIBLE
- * error.
- *
- * \param [in] mode   The UNIX permissions to set on created files.
- *                    Zero value means to open existing, but do not create.
- *
- * \return A non-zero error value on failure and 0 on success,
- *         some possible errors are:
- * \retval MDBX_VERSION_MISMATCH The version of the MDBX library doesn't match
- *                            the version that created the database environment.
- * \retval MDBX_INVALID       The environment file headers are corrupted.
- * \retval MDBX_ENOENT        The directory specified by the path parameter
- *                            doesn't exist.
- * \retval MDBX_EACCES        The user didn't have permission to access
- *                            the environment files.
- * \retval MDBX_EAGAIN        The environment was locked by another process.
- * \retval MDBX_BUSY          The \ref MDBX_EXCLUSIVE flag was specified and the
- *                            environment is in use by another process,
- *                            or the current process tries to open environment
- *                            more than once.
- * \retval MDBX_INCOMPATIBLE  Environment is already opened by another process,
- *                            but with different set of \ref MDBX_SAFE_NOSYNC,
- *                            \ref MDBX_UTTERLY_NOSYNC flags.
- *                            Or if the database is already exist and parameters
- *                            specified early by \ref mdbx_env_set_geometry()
- *                            are incompatible (i.e. different pagesize, etc).
- *
- * \retval MDBX_WANNA_RECOVERY The \ref MDBX_RDONLY flag was specified but
- *                             read-write access is required to rollback
- *                             inconsistent state after a system crash.
- *
- * \retval MDBX_TOO_LARGE      Database is too large for this process,
- *                             i.e. 32-bit process tries to open >4Gb database.
- */
-LIBMDBX_API int mdbx_env_open(MDBX_env *env, const char *pathname,
-                              MDBX_env_flags_t flags, mdbx_mode_t mode);
-
-/** \brief Deletion modes for \ref mdbx_env_delete().
- * \ingroup c_extra
- * \see mdbx_env_delete() */
-enum MDBX_env_delete_mode_t {
-  /** \brief Just delete the environment's files and directory if any.
-   * \note On POSIX systems, processes already working with the database will
-   * continue to work without interference until it close the environment.
-   * \note On Windows, the behavior of `MDB_ENV_JUST_DELETE` is different
-   * because the system does not support deleting files that are currently
-   * memory mapped. */
-  MDBX_ENV_JUST_DELETE = 0,
-  /** \brief Make sure that the environment is not being used by other
-   * processes, or return an error otherwise. */
-  MDBX_ENV_ENSURE_UNUSED = 1,
-  /** \brief Wait until other processes closes the environment before deletion.
-   */
-  MDBX_ENV_WAIT_FOR_UNUSED = 2,
-};
-#ifndef __cplusplus
-/** \ingroup c_extra */
-typedef enum MDBX_env_delete_mode_t MDBX_env_delete_mode_t;
-#endif
-
-/** \brief Delete the environment's files in a proper and multiprocess-safe way.
- * \ingroup c_extra
- *
- * \param [in] pathname  The pathname for the database or the directory in which
- *                       the database files reside.
- *
- * \param [in] mode      Special deletion mode for the environment. This
- *                       parameter must be set to one of the values described
- *                       above in the \ref MDBX_env_delete_mode_t section.
- *
- * \note The \ref MDBX_ENV_JUST_DELETE don't supported on Windows since system
- * unable to delete a memory-mapped files.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_RESULT_TRUE   No corresponding files or directories were found,
- *                            so no deletion was performed. */
-LIBMDBX_API int mdbx_env_delete(const char *pathname,
-                                MDBX_env_delete_mode_t mode);
-
-/** \brief Copy an MDBX environment to the specified path, with options.
- * \ingroup c_extra
- *
- * This function may be used to make a backup of an existing environment.
- * No lockfile is created, since it gets recreated at need.
- * \note This call can trigger significant file size growth if run in
- * parallel with write transactions, because it employs a read-only
- * transaction. See long-lived transactions under \ref restrictions section.
- *
- * \param [in] env    An environment handle returned by mdbx_env_create().
- *                    It must have already been opened successfully.
- * \param [in] dest   The pathname of a file in which the copy will reside.
- *                    This file must not be already exist, but parent directory
- *                    must be writable.
- * \param [in] flags  Special options for this operation. This parameter must
- *                    be set to 0 or by bitwise OR'ing together one or more
- *                    of the values described here:
- *
- *  - \ref MDBX_CP_COMPACT
- *      Perform compaction while copying: omit free pages and sequentially
- *      renumber all pages in output. This option consumes little bit more
- *      CPU for processing, but may running quickly than the default, on
- *      account skipping free pages.
- *
- *  - \ref MDBX_CP_FORCE_DYNAMIC_SIZE
- *      Force to make resizeable copy, i.e. dynamic size instead of fixed.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_copy(MDBX_env *env, const char *dest,
-                              MDBX_copy_flags_t flags);
-
-/** \brief Copy an environment to the specified file descriptor, with
- * options. \ingroup c_extra
- *
- * This function may be used to make a backup of an existing environment.
- * No lockfile is created, since it gets recreated at need.
- * \see mdbx_env_copy()
- *
- * \note This call can trigger significant file size growth if run in
- *       parallel with write transactions, because it employs a read-only
- *       transaction. See long-lived transactions under \ref restrictions
- *       section.
- *
- * \note Fails if the environment has suffered a page leak and the destination
- *       file descriptor is associated with a pipe, socket, or FIFO.
- *
- * \param [in] env     An environment handle returned by mdbx_env_create().
- *                     It must have already been opened successfully.
- * \param [in] fd      The file descriptor to write the copy to. It must have
- *                     already been opened for Write access.
- * \param [in] flags   Special options for this operation. \see mdbx_env_copy()
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_copy2fd(MDBX_env *env, mdbx_filehandle_t fd,
-                                 MDBX_copy_flags_t flags);
-
-/** \brief Statistics for a database in the environment
- * \ingroup c_statinfo
- * \see mdbx_env_stat_ex() \see mdbx_dbi_stat() */
-struct MDBX_stat {
-  uint32_t ms_psize; /**< Size of a database page. This is the same for all
-                        databases. */
-  uint32_t ms_depth; /**< Depth (height) of the B-tree */
-  uint64_t ms_branch_pages;   /**< Number of internal (non-leaf) pages */
-  uint64_t ms_leaf_pages;     /**< Number of leaf pages */
-  uint64_t ms_overflow_pages; /**< Number of overflow pages */
-  uint64_t ms_entries;        /**< Number of data items */
-  uint64_t ms_mod_txnid; /**< Transaction ID of committed last modification */
-};
-#ifndef __cplusplus
-/** \ingroup c_statinfo */
-typedef struct MDBX_stat MDBX_stat;
-#endif
-
-/** \brief Return statistics about the MDBX environment.
- * \ingroup c_statinfo
- *
- * At least one of env or txn argument must be non-null. If txn is passed
- * non-null then stat will be filled accordingly to the given transaction.
- * Otherwise, if txn is null, then stat will be populated by a snapshot from
- * the last committed write transaction, and at next time, other information
- * can be returned.
- *
- * Legacy mdbx_env_stat() correspond to calling \ref mdbx_env_stat_ex() with the
- * null `txn` argument.
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create()
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin()
- * \param [out] stat   The address of an \ref MDBX_stat structure where
- *                     the statistics will be copied
- * \param [in] bytes   The size of \ref MDBX_stat.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_stat_ex(const MDBX_env *env, const MDBX_txn *txn,
-                                 MDBX_stat *stat, size_t bytes);
-
-/** \brief Return statistics about the MDBX environment.
- * \ingroup c_statinfo
- * \deprecated Please use mdbx_env_stat_ex() instead. */
-MDBX_DEPRECATED LIBMDBX_INLINE_API(int, mdbx_env_stat,
-                                   (const MDBX_env *env, MDBX_stat *stat,
-                                    size_t bytes)) {
-  return mdbx_env_stat_ex(env, NULL, stat, bytes);
-}
-
-/** \brief Information about the environment
- * \ingroup c_statinfo
- * \see mdbx_env_info_ex() */
-struct MDBX_envinfo {
-  struct {
-    uint64_t lower;   /**< Lower limit for datafile size */
-    uint64_t upper;   /**< Upper limit for datafile size */
-    uint64_t current; /**< Current datafile size */
-    uint64_t shrink;  /**< Shrink threshold for datafile */
-    uint64_t grow;    /**< Growth step for datafile */
-  } mi_geo;
-  uint64_t mi_mapsize;             /**< Size of the data memory map */
-  uint64_t mi_last_pgno;           /**< Number of the last used page */
-  uint64_t mi_recent_txnid;        /**< ID of the last committed transaction */
-  uint64_t mi_latter_reader_txnid; /**< ID of the last reader transaction */
-  uint64_t mi_self_latter_reader_txnid; /**< ID of the last reader transaction
-                                           of caller process */
-  uint64_t mi_meta0_txnid, mi_meta0_sign;
-  uint64_t mi_meta1_txnid, mi_meta1_sign;
-  uint64_t mi_meta2_txnid, mi_meta2_sign;
-  uint32_t mi_maxreaders;   /**< Total reader slots in the environment */
-  uint32_t mi_numreaders;   /**< Max reader slots used in the environment */
-  uint32_t mi_dxb_pagesize; /**< Database pagesize */
-  uint32_t mi_sys_pagesize; /**< System pagesize */
-
-  /** \brief A mostly unique ID that is regenerated on each boot.
-
-   As such it can be used to identify the local machine's current boot. MDBX
-   uses such when open the database to determine whether rollback required to
-   the last steady sync point or not. I.e. if current bootid is differ from the
-   value within a database then the system was rebooted and all changes since
-   last steady sync must be reverted for data integrity. Zeros mean that no
-   relevant information is available from the system. */
-  struct {
-    struct {
-      uint64_t x, y;
-    } current, meta0, meta1, meta2;
-  } mi_bootid;
-
-  /** Bytes not explicitly synchronized to disk */
-  uint64_t mi_unsync_volume;
-  /** Current auto-sync threshold, see \ref mdbx_env_set_syncbytes(). */
-  uint64_t mi_autosync_threshold;
-  /** Time since the last steady sync in 1/65536 of second */
-  uint32_t mi_since_sync_seconds16dot16;
-  /** Current auto-sync period in 1/65536 of second,
-   * see \ref mdbx_env_set_syncperiod(). */
-  uint32_t mi_autosync_period_seconds16dot16;
-  /** Time since the last readers check in 1/65536 of second,
-   * see \ref mdbx_reader_check(). */
-  uint32_t mi_since_reader_check_seconds16dot16;
-  /** Current environment mode.
-   * The same as \ref mdbx_env_get_flags() returns. */
-  uint32_t mi_mode;
-};
-#ifndef __cplusplus
-/** \ingroup c_statinfo */
-typedef struct MDBX_envinfo MDBX_envinfo;
-#endif
-
-/** \brief Return information about the MDBX environment.
- * \ingroup c_statinfo
- *
- * At least one of env or txn argument must be non-null. If txn is passed
- * non-null then stat will be filled accordingly to the given transaction.
- * Otherwise, if txn is null, then stat will be populated by a snapshot from
- * the last committed write transaction, and at next time, other information
- * can be returned.
- *
- * Legacy \ref mdbx_env_info() correspond to calling \ref mdbx_env_info_ex()
- * with the null `txn` argument.
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create()
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin()
- * \param [out] info   The address of an \ref MDBX_envinfo structure
- *                     where the information will be copied
- * \param [in] bytes   The size of \ref MDBX_envinfo.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_info_ex(const MDBX_env *env, const MDBX_txn *txn,
-                                 MDBX_envinfo *info, size_t bytes);
-/** \brief Return information about the MDBX environment.
- * \ingroup c_statinfo
- * \deprecated Please use mdbx_env_info_ex() instead. */
-MDBX_DEPRECATED LIBMDBX_INLINE_API(int, mdbx_env_info,
-                                   (const MDBX_env *env, MDBX_envinfo *info,
-                                    size_t bytes)) {
-  return mdbx_env_info_ex(env, NULL, info, bytes);
-}
-
-/** \brief Flush the environment data buffers to disk.
- * \ingroup c_extra
- *
- * Unless the environment was opened with no-sync flags (\ref MDBX_NOMETASYNC,
- * \ref MDBX_SAFE_NOSYNC and \ref MDBX_UTTERLY_NOSYNC), then
- * data is always written an flushed to disk when \ref mdbx_txn_commit() is
- * called. Otherwise \ref mdbx_env_sync() may be called to manually write and
- * flush unsynced data to disk.
- *
- * Besides, \ref mdbx_env_sync_ex() with argument `force=false` may be used to
- * provide polling mode for lazy/asynchronous sync in conjunction with
- * \ref mdbx_env_set_syncbytes() and/or \ref mdbx_env_set_syncperiod().
- *
- * \note This call is not valid if the environment was opened with MDBX_RDONLY.
- *
- * \param [in] env      An environment handle returned by \ref mdbx_env_create()
- * \param [in] force    If non-zero, force a flush. Otherwise, If force is
- *                      zero, then will run in polling mode,
- *                      i.e. it will check the thresholds that were
- *                      set \ref mdbx_env_set_syncbytes()
- *                      and/or \ref mdbx_env_set_syncperiod() and perform flush
- *                      if at least one of the thresholds is reached.
- *
- * \param [in] nonblock Don't wait if write transaction
- *                      is running by other thread.
- *
- * \returns A non-zero error value on failure and \ref MDBX_RESULT_TRUE or 0 on
- *     success. The \ref MDBX_RESULT_TRUE means no data pending for flush
- *     to disk, and 0 otherwise. Some possible errors are:
- *
- * \retval MDBX_EACCES   the environment is read-only.
- * \retval MDBX_BUSY     the environment is used by other thread
- *                       and `nonblock=true`.
- * \retval MDBX_EINVAL   an invalid parameter was specified.
- * \retval MDBX_EIO      an error occurred during synchronization. */
-LIBMDBX_API int mdbx_env_sync_ex(MDBX_env *env, bool force, bool nonblock);
-
-/** \brief The shortcut to calling \ref mdbx_env_sync_ex() with
- * the `force=true` and `nonblock=false` arguments.
- * \ingroup c_extra */
-LIBMDBX_INLINE_API(int, mdbx_env_sync, (MDBX_env * env)) {
-  return mdbx_env_sync_ex(env, true, false);
-}
-
-/** \brief The shortcut to calling \ref mdbx_env_sync_ex() with
- * the `force=false` and `nonblock=true` arguments.
- * \ingroup c_extra */
-LIBMDBX_INLINE_API(int, mdbx_env_sync_poll, (MDBX_env * env)) {
-  return mdbx_env_sync_ex(env, false, true);
-}
-
-/** \brief Sets threshold to force flush the data buffers to disk, even any of
- * \ref MDBX_SAFE_NOSYNC flag in the environment.
- * \ingroup c_settings
- *
- * The threshold value affects all processes which operates with given
- * environment until the last process close environment or a new value will be
- * settled.
- *
- * Data is always written to disk when \ref mdbx_txn_commit() is called, but
- * the operating system may keep it buffered. MDBX always flushes the OS buffers
- * upon commit as well, unless the environment was opened with
- * \ref MDBX_SAFE_NOSYNC, \ref MDBX_UTTERLY_NOSYNC
- * or in part \ref MDBX_NOMETASYNC.
- *
- * The default is 0, than mean no any threshold checked, and no additional
- * flush will be made.
- *
- * \param [in] env         An environment handle returned by mdbx_env_create().
- * \param [in] threshold   The size in bytes of summary changes when
- *                         a synchronous flush would be made.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_INLINE_API(int, mdbx_env_set_syncbytes,
-                   (MDBX_env * env, size_t threshold)) {
-  return mdbx_env_set_option(env, MDBX_opt_sync_bytes, threshold);
-}
-
-/** \brief Sets relative period since the last unsteady commit to force flush
- * the data buffers to disk, even of \ref MDBX_SAFE_NOSYNC flag in the
- * environment.
- *
- * \ingroup c_settings
- *
- * The relative period value affects all processes which operates with given
- * environment until the last process close environment or a new value will be
- * settled.
- *
- * Data is always written to disk when \ref mdbx_txn_commit() is called, but the
- * operating system may keep it buffered. MDBX always flushes the OS buffers
- * upon commit as well, unless the environment was opened with
- * \ref MDBX_SAFE_NOSYNC or in part \ref MDBX_NOMETASYNC.
- *
- * Settled period don't checked asynchronously, but only by the
- * \ref mdbx_txn_commit() and \ref mdbx_env_sync() functions. Therefore, in
- * cases where transactions are committed infrequently and/or irregularly,
- * polling by \ref mdbx_env_sync() may be a reasonable solution to timeout
- * enforcement.
- *
- * The default is 0, than mean no any timeout checked, and no additional
- * flush will be made.
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- * \param [in] seconds_16dot16  The period in 1/65536 of second when
- *                              a synchronous flush would be made since
- *                              the last unsteady commit.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_INLINE_API(int, mdbx_env_set_syncperiod,
-                   (MDBX_env * env, unsigned seconds_16dot16)) {
-  return mdbx_env_set_option(env, MDBX_opt_sync_period, seconds_16dot16);
-}
-
-/** \brief Close the environment and release the memory map.
- * \ingroup c_opening
- *
- * Only a single thread may call this function. All transactions, databases,
- * and cursors must already be closed before calling this function. Attempts
- * to use any such handles after calling this function will cause a `SIGSEGV`.
- * The environment handle will be freed and must not be used again after this
- * call.
- *
- * \param [in] env        An environment handle returned by
- *                        \ref mdbx_env_create().
- *
- * \param [in] dont_sync  A dont'sync flag, if non-zero the last checkpoint
- *                        will be kept "as is" and may be still "weak" in the
- *                        \ref MDBX_SAFE_NOSYNC or \ref MDBX_UTTERLY_NOSYNC
- *                        modes. Such "weak" checkpoint will be ignored on
- *                        opening next time, and transactions since the last
- *                        non-weak checkpoint (meta-page update) will rolledback
- *                        for consistency guarantee.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_BUSY   The write transaction is running by other thread,
- *                     in such case \ref MDBX_env instance has NOT be destroyed
- *                     not released!
- *                     \note If any OTHER error code was returned then
- *                     given MDBX_env instance has been destroyed and released.
- *
- * \retval MDBX_EBADSIGN  Environment handle already closed or not valid,
- *                        i.e. \ref mdbx_env_close() was already called for the
- *                        `env` or was not created by \ref mdbx_env_create().
- *
- * \retval MDBX_PANIC  If \ref mdbx_env_close_ex() was called in the child
- *                     process after `fork()`. In this case \ref MDBX_PANIC
- *                     is expected, i.e. \ref MDBX_env instance was freed in
- *                     proper manner.
- *
- * \retval MDBX_EIO    An error occurred during synchronization. */
-LIBMDBX_API int mdbx_env_close_ex(MDBX_env *env, bool dont_sync);
-
-/** \brief The shortcut to calling \ref mdbx_env_close_ex() with
- * the `dont_sync=false` argument.
- * \ingroup c_opening */
-LIBMDBX_INLINE_API(int, mdbx_env_close, (MDBX_env * env)) {
-  return mdbx_env_close_ex(env, false);
-}
-
-/** \brief Set environment flags.
- * \ingroup c_settings
- *
- * This may be used to set some flags in addition to those from
- * mdbx_env_open(), or to unset these flags.
- * \see mdbx_env_get_flags()
- *
- * \note In contrast to LMDB, the MDBX serialize threads via mutex while
- * changing the flags. Therefore this function will be blocked while a write
- * transaction running by other thread, or \ref MDBX_BUSY will be returned if
- * function called within a write transaction.
- *
- * \param [in] env      An environment handle returned
- *                      by \ref mdbx_env_create().
- * \param [in] flags    The \ref env_flags to change, bitwise OR'ed together.
- * \param [in] onoff    A non-zero value sets the flags, zero clears them.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_env_set_flags(MDBX_env *env, MDBX_env_flags_t flags,
-                                   bool onoff);
-
-/** \brief Get environment flags.
- * \ingroup c_statinfo
- * \see mdbx_env_set_flags()
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- * \param [out] flags  The address of an integer to store the flags.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL An invalid parameter was specified. */
-LIBMDBX_API int mdbx_env_get_flags(const MDBX_env *env, unsigned *flags);
-
-/** \brief Return the path that was used in mdbx_env_open().
- * \ingroup c_statinfo
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create()
- * \param [out] dest   Address of a string pointer to contain the path.
- *                     This is the actual string in the environment, not a
- *                     copy. It should not be altered in any way.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_env_get_path(const MDBX_env *env, const char **dest);
-
-/** \brief Return the file descriptor for the given environment.
- * \ingroup c_statinfo
- *
- * \note All MDBX file descriptors have `FD_CLOEXEC` and
- *       couldn't be used after exec() and or `fork()`.
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- * \param [out] fd   Address of a int to contain the descriptor.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_env_get_fd(const MDBX_env *env, mdbx_filehandle_t *fd);
-
-/** \brief Set all size-related parameters of environment, including page size
- * and the min/max size of the memory map. \ingroup c_settings
- *
- * In contrast to LMDB, the MDBX provide automatic size management of an
- * database according the given parameters, including shrinking and resizing
- * on the fly. From user point of view all of these just working. Nevertheless,
- * it is reasonable to know some details in order to make optimal decisions
- * when choosing parameters.
- *
- * Both \ref mdbx_env_info_ex() and legacy \ref mdbx_env_info() are inapplicable
- * to read-only opened environment.
- *
- * Both \ref mdbx_env_info_ex() and legacy \ref mdbx_env_info() could be called
- * either before or after \ref mdbx_env_open(), either within the write
- * transaction running by current thread or not:
- *
- *  - In case \ref mdbx_env_info_ex() or legacy \ref mdbx_env_info() was called
- *    BEFORE \ref mdbx_env_open(), i.e. for closed environment, then the
- *    specified parameters will be used for new database creation, or will be
- *    applied during opening if database exists and no other process using it.
- *
- *    If the database is already exist, opened with \ref MDBX_EXCLUSIVE or not
- *    used by any other process, and parameters specified by
- *    \ref mdbx_env_set_geometry() are incompatible (i.e. for instance,
- *    different page size) then \ref mdbx_env_open() will return
- *    \ref MDBX_INCOMPATIBLE error.
- *
- *    In another way, if database will opened read-only or will used by other
- *    process during calling \ref mdbx_env_open() that specified parameters will
- *    silently discarded (open the database with \ref MDBX_EXCLUSIVE flag
- *    to avoid this).
- *
- *  - In case \ref mdbx_env_info_ex() or legacy \ref mdbx_env_info() was called
- *    after \ref mdbx_env_open() WITHIN the write transaction running by current
- *    thread, then specified parameters will be applied as a part of write
- *    transaction, i.e. will not be visible to any others processes until the
- *    current write transaction has been committed by the current process.
- *    However, if transaction will be aborted, then the database file will be
- *    reverted to the previous size not immediately, but when a next transaction
- *    will be committed or when the database will be opened next time.
- *
- *  - In case \ref mdbx_env_info_ex() or legacy \ref mdbx_env_info() was called
- *    after \ref mdbx_env_open() but OUTSIDE a write transaction, then MDBX will
- *    execute internal pseudo-transaction to apply new parameters (but only if
- *    anything has been changed), and changes be visible to any others processes
- *    immediately after succesful completion of function.
- *
- * Essentially a concept of "automatic size management" is simple and useful:
- *  - There are the lower and upper bound of the database file size;
- *  - There is the growth step by which the database file will be increased,
- *    in case of lack of space.
- *  - There is the threshold for unused space, beyond which the database file
- *    will be shrunk.
- *  - The size of the memory map is also the maximum size of the database.
- *  - MDBX will automatically manage both the size of the database and the size
- *    of memory map, according to the given parameters.
- *
- * So, there some considerations about choosing these parameters:
- *  - The lower bound allows you to prevent database shrinking below some
- *    rational size to avoid unnecessary resizing costs.
- *  - The upper bound allows you to prevent database growth above some rational
- *    size. Besides, the upper bound defines the linear address space
- *    reservation in each process that opens the database. Therefore changing
- *    the upper bound is costly and may be required reopening environment in
- *    case of \ref MDBX_UNABLE_EXTEND_MAPSIZE errors, and so on. Therefore, this
- *    value should be chosen reasonable as large as possible, to accommodate
- *    future growth of the database.
- *  - The growth step must be greater than zero to allow the database to grow,
- *    but also reasonable not too small, since increasing the size by little
- *    steps will result a large overhead.
- *  - The shrink threshold must be greater than zero to allow the database
- *    to shrink but also reasonable not too small (to avoid extra overhead) and
- *    not less than growth step to avoid up-and-down flouncing.
- *  - The current size (i.e. size_now argument) is an auxiliary parameter for
- *    simulation legacy \ref mdbx_env_set_mapsize() and as workaround Windows
- *    issues (see below).
- *
- * Unfortunately, Windows has is a several issues
- * with resizing of memory-mapped file:
- *  - Windows unable shrinking a memory-mapped file (i.e memory-mapped section)
- *    in any way except unmapping file entirely and then map again. Moreover,
- *    it is impossible in any way if a memory-mapped file is used more than
- *    one process.
- *  - Windows does not provide the usual API to augment a memory-mapped file
- *    (that is, a memory-mapped partition), but only by using "Native API"
- *    in an undocumented way.
- *
- * MDBX bypasses all Windows issues, but at a cost:
- *  - Ability to resize database on the fly requires an additional lock
- *    and release `SlimReadWriteLock during` each read-only transaction.
- *  - During resize all in-process threads should be paused and then resumed.
- *  - Shrinking of database file is performed only when it used by single
- *    process, i.e. when a database closes by the last process or opened
- *    by the first.
- *  = Therefore, the size_now argument may be useful to set database size
- *    by the first process which open a database, and thus avoid expensive
- *    remapping further.
- *
- * For create a new database with particular parameters, including the page
- * size, \ref mdbx_env_set_geometry() should be called after
- * \ref mdbx_env_create() and before mdbx_env_open(). Once the database is
- * created, the page size cannot be changed. If you do not specify all or some
- * of the parameters, the corresponding default values will be used. For
- * instance, the default for database size is 10485760 bytes.
- *
- * If the mapsize is increased by another process, MDBX silently and
- * transparently adopt these changes at next transaction start. However,
- * \ref mdbx_txn_begin() will return \ref MDBX_UNABLE_EXTEND_MAPSIZE if new
- * mapping size could not be applied for current process (for instance if
- * address space is busy).  Therefore, in the case of
- * \ref MDBX_UNABLE_EXTEND_MAPSIZE error you need close and reopen the
- * environment to resolve error.
- *
- * \note Actual values may be different than your have specified because of
- * rounding to specified database page size, the system page size and/or the
- * size of the system virtual memory management unit. You can get actual values
- * by \ref mdbx_env_sync_ex() or see by using the tool `mdbx_chk` with the `-v`
- * option.
- *
- * Legacy \ref mdbx_env_set_mapsize() correspond to calling
- * \ref mdbx_env_set_geometry() with the arguments `size_lower`, `size_now`,
- * `size_upper` equal to the `size` and `-1` (i.e. default) for all other
- * parameters.
- *
- * \param [in] env         An environment handle returned
- *                         by \ref mdbx_env_create()
- *
- * \param [in] size_lower  The lower bound of database size in bytes.
- *                         Zero value means "minimal acceptable",
- *                         and negative means "keep current or use default".
- *
- * \param [in] size_now    The size in bytes to setup the database size for
- *                         now. Zero value means "minimal acceptable", and
- *                         negative means "keep current or use default". So,
- *                         it is recommended always pass -1 in this argument
- *                         except some special cases.
- *
- * \param [in] size_upper The upper bound of database size in bytes.
- *                        Zero value means "minimal acceptable",
- *                        and negative means "keep current or use default".
- *                        It is recommended to avoid change upper bound while
- *                        database is used by other processes or threaded
- *                        (i.e. just pass -1 in this argument except absolutely
- *                        necessary). Otherwise you must be ready for
- *                        \ref MDBX_UNABLE_EXTEND_MAPSIZE error(s), unexpected
- *                        pauses during remapping and/or system errors like
- *                        "address busy", and so on. In other words, there
- *                        is no way to handle a growth of the upper bound
- *                        robustly because there may be a lack of appropriate
- *                        system resources (which are extremely volatile in
- *                        a multi-process multi-threaded environment).
- *
- * \param [in] growth_step  The growth step in bytes, must be greater than
- *                          zero to allow the database to grow. Negative value
- *                          means "keep current or use default".
- *
- * \param [in] shrink_threshold  The shrink threshold in bytes, must be greater
- *                               than zero to allow the database to shrink and
- *                               greater than growth_step to avoid shrinking
- *                               right after grow.
- *                               Negative value means "keep current
- *                               or use default". Default is 2*growth_step.
- *
- * \param [in] pagesize          The database page size for new database
- *                               creation or -1 otherwise. Must be power of 2
- *                               in the range between \ref MDBX_MIN_PAGESIZE and
- *                               \ref MDBX_MAX_PAGESIZE. Zero value means
- *                               "minimal acceptable", and negative means
- *                               "keep current or use default".
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL    An invalid parameter was specified,
- *                        or the environment has an active write transaction.
- * \retval MDBX_EPERM     Specific for Windows: Shrinking was disabled before
- *                        and now it wanna be enabled, but there are reading
- *                        threads that don't use the additional `SRWL` (that
- *                        is required to avoid Windows issues).
- * \retval MDBX_EACCESS   The environment opened in read-only.
- * \retval MDBX_MAP_FULL  Specified size smaller than the space already
- *                        consumed by the environment.
- * \retval MDBX_TOO_LARGE Specified size is too large, i.e. too many pages for
- *                        given size, or a 32-bit process requests too much
- *                        bytes for the 32-bit address space. */
-LIBMDBX_API int mdbx_env_set_geometry(MDBX_env *env, intptr_t size_lower,
-                                      intptr_t size_now, intptr_t size_upper,
-                                      intptr_t growth_step,
-                                      intptr_t shrink_threshold,
-                                      intptr_t pagesize);
-
-/** \deprecated Please use \ref mdbx_env_set_geometry() instead.
- * \ingroup c_settings */
-MDBX_DEPRECATED LIBMDBX_INLINE_API(int, mdbx_env_set_mapsize,
-                                   (MDBX_env * env, size_t size)) {
-  return mdbx_env_set_geometry(env, size, size, size, -1, -1, -1);
-}
-
-/** \brief Find out whether to use readahead or not, based on the given database
- * size and the amount of available memory. \ingroup c_extra
- *
- * \param [in] volume      The expected database size in bytes.
- * \param [in] redundancy  Additional reserve or overload in case of negative
- *                         value.
- *
- * \returns A \ref MDBX_RESULT_TRUE or \ref MDBX_RESULT_FALSE value,
- *          otherwise the error code:
- * \retval MDBX_RESULT_TRUE   Readahead is reasonable.
- * \retval MDBX_RESULT_FALSE  Readahead is NOT reasonable,
- *                            i.e. \ref MDBX_NORDAHEAD is useful to
- *                            open environment by \ref mdbx_env_open().
- * \retval Otherwise the error code. */
-LIBMDBX_API int mdbx_is_readahead_reasonable(size_t volume,
-                                             intptr_t redundancy);
-
-/** \brief Returns the minimal database page size in bytes.
- * \ingroup c_statinfo */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_INLINE_API(intptr_t, mdbx_limits_pgsize_min,
-                                               (void)) {
-  return MDBX_MIN_PAGESIZE;
-}
-
-/** \brief Returns the maximal database page size in bytes.
- * \ingroup c_statinfo */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_INLINE_API(intptr_t, mdbx_limits_pgsize_max,
-                                               (void)) {
-  return MDBX_MAX_PAGESIZE;
-}
-
-/** \brief Returns minimal database size in bytes for given page size,
- * or -1 if pagesize is invalid.
- * \ingroup c_statinfo */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API intptr_t
-mdbx_limits_dbsize_min(intptr_t pagesize);
-
-/** \brief Returns maximal database size in bytes for given page size,
- * or -1 if pagesize is invalid.
- * \ingroup c_statinfo */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API intptr_t
-mdbx_limits_dbsize_max(intptr_t pagesize);
-
-/** \brief Returns maximal key size in bytes for given page size
- * and database flags, or -1 if pagesize is invalid.
- * \ingroup c_statinfo
- * \see db_flags */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API intptr_t
-mdbx_limits_keysize_max(intptr_t pagesize, MDBX_db_flags_t flags);
-
-/** \brief Returns maximal data size in bytes for given page size
- * and database flags, or -1 if pagesize is invalid.
- * \ingroup c_statinfo
- * \see db_flags */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API intptr_t
-mdbx_limits_valsize_max(intptr_t pagesize, MDBX_db_flags_t flags);
-
-/** \brief Returns maximal write transaction size (i.e. limit for summary volume
- * of dirty pages) in bytes for given page size, or -1 if pagesize is invalid.
- * \ingroup c_statinfo */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API intptr_t
-mdbx_limits_txnsize_max(intptr_t pagesize);
-
-/** \brief Set the maximum number of threads/reader slots for for all processes
- * interacts with the database. \ingroup c_settings
- *
- * \details This defines the number of slots in the lock table that is used to
- * track readers in the the environment. The default is about 100 for 4K system
- * page size. Starting a read-only transaction normally ties a lock table slot
- * to the current thread until the environment closes or the thread exits. If
- * \ref MDBX_NOTLS is in use, \ref mdbx_txn_begin() instead ties the slot to the
- * \ref MDBX_txn object until it or the \ref MDBX_env object is destroyed.
- * This function may only be called after \ref mdbx_env_create() and before
- * \ref mdbx_env_open(), and has an effect only when the database is opened by
- * the first process interacts with the database.
- * \see mdbx_env_get_maxreaders()
- *
- * \param [in] env       An environment handle returned
- *                       by \ref mdbx_env_create().
- * \param [in] readers   The maximum number of reader lock table slots.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL   An invalid parameter was specified.
- * \retval MDBX_EPERM    The environment is already open. */
-LIBMDBX_INLINE_API(int, mdbx_env_set_maxreaders,
-                   (MDBX_env * env, unsigned readers)) {
-  return mdbx_env_set_option(env, MDBX_opt_max_readers, readers);
-}
-
-/** \brief Get the maximum number of threads/reader slots for the environment.
- * \ingroup c_statinfo
- * \see mdbx_env_set_maxreaders()
- *
- * \param [in] env       An environment handle returned
- *                       by \ref mdbx_env_create().
- * \param [out] readers  Address of an integer to store the number of readers.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL   An invalid parameter was specified. */
-LIBMDBX_INLINE_API(int, mdbx_env_get_maxreaders,
-                   (const MDBX_env *env, unsigned *readers)) {
-  int rc = MDBX_EINVAL;
-  if (readers) {
-    uint64_t proxy = 0;
-    rc = mdbx_env_get_option(env, MDBX_opt_max_readers, &proxy);
-    *readers = (unsigned)proxy;
-  }
-  return rc;
-}
-
-/** \brief Set the maximum number of named databases for the environment.
- * \ingroup c_settings
- *
- * This function is only needed if multiple databases will be used in the
- * environment. Simpler applications that use the environment as a single
- * unnamed database can ignore this option.
- * This function may only be called after \ref mdbx_env_create() and before
- * \ref mdbx_env_open().
- *
- * Currently a moderate number of slots are cheap but a huge number gets
- * expensive: 7-120 words per transaction, and every \ref mdbx_dbi_open()
- * does a linear search of the opened slots.
- * \see mdbx_env_get_maxdbs()
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- * \param [in] dbs   The maximum number of databases.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL   An invalid parameter was specified.
- * \retval MDBX_EPERM    The environment is already open. */
-LIBMDBX_INLINE_API(int, mdbx_env_set_maxdbs, (MDBX_env * env, MDBX_dbi dbs)) {
-  return mdbx_env_set_option(env, MDBX_opt_max_db, dbs);
-}
-
-/** \brief Get the maximum number of named databases for the environment.
- * \ingroup c_statinfo
- * \see mdbx_env_set_maxdbs()
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- * \param [out] dbs  Address to store the maximum number of databases.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EINVAL   An invalid parameter was specified. */
-LIBMDBX_INLINE_API(int, mdbx_env_get_maxdbs,
-                   (const MDBX_env *env, MDBX_dbi *dbs)) {
-  int rc = MDBX_EINVAL;
-  if (dbs) {
-    uint64_t proxy = 0;
-    rc = mdbx_env_get_option(env, MDBX_opt_max_db, &proxy);
-    *dbs = (MDBX_dbi)proxy;
-  }
-  return rc;
-}
-
-/** \brief Returns the default size of database page for the current system.
- * \ingroup c_statinfo
- * \details Default size of database page depends on the size of the system
- * page and usually exactly match it. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API size_t mdbx_default_pagesize(void);
-
-/** \brief Get the maximum size of keys can write.
- * \ingroup c_statinfo
- *
- * \param [in] env    An environment handle returned by \ref mdbx_env_create().
- * \param [in] flags  Database options (\ref MDBX_DUPSORT, \ref MDBX_INTEGERKEY
- *                    and so on). \see db_flags
- *
- * \returns The maximum size of a key can write,
- *          or -1 if something is wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int
-mdbx_env_get_maxkeysize_ex(const MDBX_env *env, MDBX_db_flags_t flags);
-
-/** \brief Get the maximum size of data we can write.
- * \ingroup c_statinfo
- *
- * \param [in] env    An environment handle returned by \ref mdbx_env_create().
- * \param [in] flags  Database options (\ref MDBX_DUPSORT, \ref MDBX_INTEGERKEY
- *                    and so on). \see db_flags
- *
- * \returns The maximum size of a data can write,
- *          or -1 if something is wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int
-mdbx_env_get_maxvalsize_ex(const MDBX_env *env, MDBX_db_flags_t flags);
-
-/** \deprecated Please use \ref mdbx_env_get_maxkeysize_ex()
- *              and/or \ref mdbx_env_get_maxvalsize_ex()
- * \ingroup c_statinfo */
-MDBX_NOTHROW_PURE_FUNCTION MDBX_DEPRECATED LIBMDBX_API int
-mdbx_env_get_maxkeysize(const MDBX_env *env);
-
-/** \brief Set application information associated with the \ref MDBX_env.
- * \ingroup c_settings
- * \see mdbx_env_get_userctx()
- *
- * \param [in] env  An environment handle returned by \ref mdbx_env_create().
- * \param [in] ctx  An arbitrary pointer for whatever the application needs.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_set_userctx(MDBX_env *env, void *ctx);
-
-/** \brief Get the application information associated with the MDBX_env.
- * \ingroup c_statinfo
- * \see mdbx_env_set_userctx()
- *
- * \param [in] env An environment handle returned by \ref mdbx_env_create()
- * \returns The pointer set by \ref mdbx_env_set_userctx()
- *          or `NULL` if something wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API void *
-mdbx_env_get_userctx(const MDBX_env *env);
-
-/** \brief Create a transaction with a user provided context pointer
- * for use with the environment.
- * \ingroup c_transactions
- *
- * The transaction handle may be discarded using \ref mdbx_txn_abort()
- * or \ref mdbx_txn_commit().
- * \see mdbx_txn_begin()
- *
- * \note A transaction and its cursors must only be used by a single thread,
- * and a thread may only have a single transaction at a time. If \ref MDBX_NOTLS
- * is in use, this does not apply to read-only transactions.
- *
- * \note Cursors may not span transactions.
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- *
- * \param [in] parent  If this parameter is non-NULL, the new transaction will
- *                     be a nested transaction, with the transaction indicated
- *                     by parent as its parent. Transactions may be nested
- *                     to any level. A parent transaction and its cursors may
- *                     not issue any other operations than mdbx_txn_commit and
- *                     \ref mdbx_txn_abort() while it has active child
- *                     transactions.
- *
- * \param [in] flags   Special options for this transaction. This parameter
- *                     must be set to 0 or by bitwise OR'ing together one
- *                     or more of the values described here:
- *                      - \ref MDBX_RDONLY   This transaction will not perform
- *                                           any write operations.
- *
- *                      - \ref MDBX_TXN_TRY  Do not block when starting
- *                                           a write transaction.
- *
- *                      - \ref MDBX_SAFE_NOSYNC, \ref MDBX_NOMETASYNC.
- *                        Do not sync data to disk corresponding
- *                        to \ref MDBX_NOMETASYNC or \ref MDBX_SAFE_NOSYNC
- *                        description. \see sync_modes
- *
- * \param [out] txn    Address where the new MDBX_txn handle will be stored.
- *
- * \param [in] context A pointer to application context to be associated with
- *                     created transaction and could be retrieved by
- *                     \ref mdbx_txn_get_userctx() until transaction finished.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_PANIC         A fatal error occurred earlier and the
- *                            environment must be shut down.
- * \retval MDBX_UNABLE_EXTEND_MAPSIZE  Another process wrote data beyond
- *                                     this MDBX_env's mapsize and this
- *                                     environment map must be resized as well.
- *                                     See \ref mdbx_env_set_mapsize().
- * \retval MDBX_READERS_FULL  A read-only transaction was requested and
- *                            the reader lock table is full.
- *                            See \ref mdbx_env_set_maxreaders().
- * \retval MDBX_ENOMEM        Out of memory.
- * \retval MDBX_BUSY          The write transaction is already started by the
- *                            current thread. */
-LIBMDBX_API int mdbx_txn_begin_ex(MDBX_env *env, MDBX_txn *parent,
-                                  MDBX_txn_flags_t flags, MDBX_txn **txn,
-                                  void *context);
-
-/** \brief Create a transaction for use with the environment.
- * \ingroup c_transactions
- *
- * The transaction handle may be discarded using \ref mdbx_txn_abort()
- * or \ref mdbx_txn_commit().
- * \see mdbx_txn_begin_ex()
- *
- * \note A transaction and its cursors must only be used by a single thread,
- * and a thread may only have a single transaction at a time. If \ref MDBX_NOTLS
- * is in use, this does not apply to read-only transactions.
- *
- * \note Cursors may not span transactions.
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- *
- * \param [in] parent  If this parameter is non-NULL, the new transaction will
- *                     be a nested transaction, with the transaction indicated
- *                     by parent as its parent. Transactions may be nested
- *                     to any level. A parent transaction and its cursors may
- *                     not issue any other operations than mdbx_txn_commit and
- *                     \ref mdbx_txn_abort() while it has active child
- *                     transactions.
- *
- * \param [in] flags   Special options for this transaction. This parameter
- *                     must be set to 0 or by bitwise OR'ing together one
- *                     or more of the values described here:
- *                      - \ref MDBX_RDONLY   This transaction will not perform
- *                                           any write operations.
- *
- *                      - \ref MDBX_TXN_TRY  Do not block when starting
- *                                           a write transaction.
- *
- *                      - \ref MDBX_SAFE_NOSYNC, \ref MDBX_NOMETASYNC.
- *                        Do not sync data to disk corresponding
- *                        to \ref MDBX_NOMETASYNC or \ref MDBX_SAFE_NOSYNC
- *                        description. \see sync_modes
- *
- * \param [out] txn    Address where the new MDBX_txn handle will be stored.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_PANIC         A fatal error occurred earlier and the
- *                            environment must be shut down.
- * \retval MDBX_UNABLE_EXTEND_MAPSIZE  Another process wrote data beyond
- *                                     this MDBX_env's mapsize and this
- *                                     environment map must be resized as well.
- *                                     See \ref mdbx_env_set_mapsize().
- * \retval MDBX_READERS_FULL  A read-only transaction was requested and
- *                            the reader lock table is full.
- *                            See \ref mdbx_env_set_maxreaders().
- * \retval MDBX_ENOMEM        Out of memory.
- * \retval MDBX_BUSY          The write transaction is already started by the
- *                            current thread. */
-LIBMDBX_INLINE_API(int, mdbx_txn_begin,
-                   (MDBX_env * env, MDBX_txn *parent, MDBX_txn_flags_t flags,
-                    MDBX_txn **txn)) {
-  return mdbx_txn_begin_ex(env, parent, flags, txn, NULL);
-}
-
-/** \brief Set application information associated with the \ref MDBX_txn.
- * \ingroup c_transactions
- * \see mdbx_txn_get_userctx()
- *
- * \param [in] txn  An transaction handle returned by \ref mdbx_txn_begin_ex()
- *                  or \ref mdbx_txn_begin().
- * \param [in] ctx  An arbitrary pointer for whatever the application needs.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_txn_set_userctx(MDBX_txn *txn, void *ctx);
-
-/** \brief Get the application information associated with the MDBX_txn.
- * \ingroup c_transactions
- * \see mdbx_txn_set_userctx()
- *
- * \param [in] txn  An transaction handle returned by \ref mdbx_txn_begin_ex()
- *                  or \ref mdbx_txn_begin().
- * \returns The pointer which was passed via the `context` parameter
- *          of `mdbx_txn_begin_ex()` or set by \ref mdbx_txn_set_userctx(),
- *          or `NULL` if something wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API void *
-mdbx_txn_get_userctx(const MDBX_txn *txn);
-
-/** \brief Information about the transaction
- * \ingroup c_statinfo
- * \see mdbx_txn_info */
-struct MDBX_txn_info {
-  /** The ID of the transaction. For a READ-ONLY transaction, this corresponds
-      to the snapshot being read. */
-  uint64_t txn_id;
-
-  /** For READ-ONLY transaction: the lag from a recent MVCC-snapshot, i.e. the
-     number of committed transaction since read transaction started.
-     For WRITE transaction (provided if `scan_rlt=true`): the lag of the oldest
-     reader from current transaction (i.e. at least 1 if any reader running). */
-  uint64_t txn_reader_lag;
-
-  /** Used space by this transaction, i.e. corresponding to the last used
-   * database page. */
-  uint64_t txn_space_used;
-
-  /** Current size of database file. */
-  uint64_t txn_space_limit_soft;
-
-  /** Upper bound for size the database file, i.e. the value `size_upper`
-     argument of the appropriate call of \ref mdbx_env_set_geometry(). */
-  uint64_t txn_space_limit_hard;
-
-  /** For READ-ONLY transaction: The total size of the database pages that were
-     retired by committed write transactions after the reader's MVCC-snapshot,
-     i.e. the space which would be freed after the Reader releases the
-     MVCC-snapshot for reuse by completion read transaction.
-     For WRITE transaction: The summarized size of the database pages that were
-     retired for now due Copy-On-Write during this transaction. */
-  uint64_t txn_space_retired;
-
-  /** For READ-ONLY transaction: the space available for writer(s) and that
-     must be exhausted for reason to call the Handle-Slow-Readers callback for
-     this read transaction.
-     For WRITE transaction: the space inside transaction
-     that left to `MDBX_TXN_FULL` error. */
-  uint64_t txn_space_leftover;
-
-  /** For READ-ONLY transaction (provided if `scan_rlt=true`): The space that
-     actually become available for reuse when only this transaction will be
-     finished.
-     For WRITE transaction: The summarized size of the dirty database
-     pages that generated during this transaction. */
-  uint64_t txn_space_dirty;
-};
-#ifndef __cplusplus
-/** \ingroup c_statinfo */
-typedef struct MDBX_txn_info MDBX_txn_info;
-#endif
-
-/** \brief Return information about the MDBX transaction.
- * \ingroup c_statinfo
- *
- * \param [in] txn        A transaction handle returned by \ref mdbx_txn_begin()
- * \param [out] info      The address of an \ref MDBX_txn_info structure
- *                        where the information will be copied.
- * \param [in] scan_rlt   The boolean flag controls the scan of the read lock
- *                        table to provide complete information. Such scan
- *                        is relatively expensive and you can avoid it
- *                        if corresponding fields are not needed.
- *                        See description of \ref MDBX_txn_info.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_txn_info(const MDBX_txn *txn, MDBX_txn_info *info,
-                              bool scan_rlt);
-
-/** \brief Returns the transaction's MDBX_env.
- * \ingroup c_transactions
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin() */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API MDBX_env *
-mdbx_txn_env(const MDBX_txn *txn);
-
-/** \brief Return the transaction's flags.
- * \ingroup c_transactions
- *
- * This returns the flags associated with this transaction.
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A transaction flags, valid if input is an valid transaction,
- *          otherwise -1. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int mdbx_txn_flags(const MDBX_txn *txn);
-
-/** \brief Return the transaction's ID.
- * \ingroup c_statinfo
- *
- * This returns the identifier associated with this transaction. For a
- * read-only transaction, this corresponds to the snapshot being read;
- * concurrent readers will frequently have the same transaction ID.
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A transaction ID, valid if input is an active transaction,
- *          otherwise 0. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API uint64_t
-mdbx_txn_id(const MDBX_txn *txn);
-
-/** \brief Latency of commit stages in 1/65536 of seconds units.
- * \warning This structure may be changed in future releases.
- * \see mdbx_txn_commit_ex() */
-struct MDBX_commit_latency {
-  /** \brief Duration of preparation (commit child transactions, update
-   * sub-databases records and cursors destroying). */
-  uint32_t preparation;
-  /** \brief Duration of GC/freeDB handling & updation. */
-  uint32_t gc;
-  /** \brief Duration of internal audit if enabled. */
-  uint32_t audit;
-  /** \brief Duration of writing dirty/modified data pages. */
-  uint32_t write;
-  /** \brief Duration of syncing written data to the dist/storage. */
-  uint32_t sync;
-  /** \brief Duration of transaction ending (releasing resources). */
-  uint32_t ending;
-  /** \brief The total duration of a commit. */
-  uint32_t whole;
-};
-#ifndef __cplusplus
-/** \ingroup c_statinfo */
-typedef struct MDBX_commit_latency MDBX_commit_latency;
-#endif
-
-/** \brief Commit all the operations of a transaction into the database and
- * collect latency information.
- * \see mdbx_txn_commit()
- * \ingroup c_statinfo
- * \warning This function may be changed in future releases. */
-LIBMDBX_API int mdbx_txn_commit_ex(MDBX_txn *txn, MDBX_commit_latency *latency);
-
-/** \brief Commit all the operations of a transaction into the database.
- * \ingroup c_transactions
- *
- * If the current thread is not eligible to manage the transaction then
- * the \ref MDBX_THREAD_MISMATCH error will returned. Otherwise the transaction
- * will be committed and its handle is freed. If the transaction cannot
- * be committed, it will be aborted with the corresponding error returned.
- *
- * Thus, a result other than \ref MDBX_THREAD_MISMATCH means that the
- * transaction is terminated:
- *  - Resources are released;
- *  - Transaction handle is invalid;
- *  - Cursor(s) associated with transaction must not be used, except with
- *    mdbx_cursor_renew() and \ref mdbx_cursor_close().
- *    Such cursor(s) must be closed explicitly by \ref mdbx_cursor_close()
- *    before or after transaction commit, either can be reused with
- *    \ref mdbx_cursor_renew() until it will be explicitly closed by
- *    \ref mdbx_cursor_close().
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_RESULT_TRUE      Transaction was aborted since it should
- *                               be aborted due to previous errors.
- * \retval MDBX_PANIC            A fatal error occurred earlier
- *                               and the environment must be shut down.
- * \retval MDBX_BAD_TXN          Transaction is already finished or never began.
- * \retval MDBX_EBADSIGN         Transaction object has invalid signature,
- *                               e.g. transaction was already terminated
- *                               or memory was corrupted.
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL           Transaction handle is NULL.
- * \retval MDBX_ENOSPC           No more disk space.
- * \retval MDBX_EIO              A system-level I/O error occurred.
- * \retval MDBX_ENOMEM           Out of memory. */
-LIBMDBX_INLINE_API(int, mdbx_txn_commit, (MDBX_txn * txn)) {
-  return mdbx_txn_commit_ex(txn, NULL);
-}
-
-/** \brief Abandon all the operations of the transaction instead of saving them.
- * \ingroup c_transactions
- *
- * The transaction handle is freed. It and its cursors must not be used again
- * after this call, except with \ref mdbx_cursor_renew() and
- * \ref mdbx_cursor_close().
- *
- * If the current thread is not eligible to manage the transaction then
- * the \ref MDBX_THREAD_MISMATCH error will returned. Otherwise the transaction
- * will be aborted and its handle is freed. Thus, a result other than
- * \ref MDBX_THREAD_MISMATCH means that the transaction is terminated:
- *  - Resources are released;
- *  - Transaction handle is invalid;
- *  - Cursor(s) associated with transaction must not be used, except with
- *    \ref mdbx_cursor_renew() and \ref mdbx_cursor_close().
- *    Such cursor(s) must be closed explicitly by \ref mdbx_cursor_close()
- *    before or after transaction abort, either can be reused with
- *    \ref mdbx_cursor_renew() until it will be explicitly closed by
- *    \ref mdbx_cursor_close().
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_PANIC            A fatal error occurred earlier and
- *                               the environment must be shut down.
- * \retval MDBX_BAD_TXN          Transaction is already finished or never began.
- * \retval MDBX_EBADSIGN         Transaction object has invalid signature,
- *                               e.g. transaction was already terminated
- *                               or memory was corrupted.
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL           Transaction handle is NULL. */
-LIBMDBX_API int mdbx_txn_abort(MDBX_txn *txn);
-
-/** \brief Marks transaction as broken.
- * \ingroup c_transactions
- *
- * Function keeps the transaction handle and corresponding locks, but it
- * is not possible to perform any operations in a broken transaction.
- * Broken transaction must then be aborted explicitly later.
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \see mdbx_txn_abort() \see mdbx_txn_reset() \see mdbx_txn_commit()
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_txn_break(MDBX_txn *txn);
-
-/** \brief Reset a read-only transaction.
- * \ingroup c_transactions
- *
- * Abort the read-only transaction like \ref mdbx_txn_abort(), but keep the
- * transaction handle. Therefore \ref mdbx_txn_renew() may reuse the handle.
- * This saves allocation overhead if the process will start a new read-only
- * transaction soon, and also locking overhead if \ref MDBX_NOTLS is in use. The
- * reader table lock is released, but the table slot stays tied to its thread
- * or \ref MDBX_txn. Use \ref mdbx_txn_abort() to discard a reset handle, and to
- * free its lock table slot if \ref MDBX_NOTLS is in use.
- *
- * Cursors opened within the transaction must not be used again after this
- * call, except with \ref mdbx_cursor_renew() and \ref mdbx_cursor_close().
- *
- * Reader locks generally don't interfere with writers, but they keep old
- * versions of database pages allocated. Thus they prevent the old pages from
- * being reused when writers commit new data, and so under heavy load the
- * database size may grow much more rapidly than otherwise.
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_PANIC            A fatal error occurred earlier and
- *                               the environment must be shut down.
- * \retval MDBX_BAD_TXN          Transaction is already finished or never began.
- * \retval MDBX_EBADSIGN         Transaction object has invalid signature,
- *                               e.g. transaction was already terminated
- *                               or memory was corrupted.
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL           Transaction handle is NULL. */
-LIBMDBX_API int mdbx_txn_reset(MDBX_txn *txn);
-
-/** \brief Renew a read-only transaction.
- * \ingroup c_transactions
- *
- * This acquires a new reader lock for a transaction handle that had been
- * released by \ref mdbx_txn_reset(). It must be called before a reset
- * transaction may be used again.
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_PANIC            A fatal error occurred earlier and
- *                               the environment must be shut down.
- * \retval MDBX_BAD_TXN          Transaction is already finished or never began.
- * \retval MDBX_EBADSIGN         Transaction object has invalid signature,
- *                               e.g. transaction was already terminated
- *                               or memory was corrupted.
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL           Transaction handle is NULL. */
-LIBMDBX_API int mdbx_txn_renew(MDBX_txn *txn);
-
-/** \brief The fours integers markers (aka "canary") associated with the
- * environment. \ingroup c_crud \see mdbx_canary_set() \see mdbx_canary_get()
- *
- * The `x`, `y` and `z` values could be set by \ref mdbx_canary_put(), while the
- * 'v' will be always set to the transaction number. Updated values becomes
- * visible outside the current transaction only after it was committed. Current
- * values could be retrieved by \ref mdbx_canary_get(). */
-struct MDBX_canary {
-  uint64_t x, y, z, v;
-};
-#ifndef __cplusplus
-/** \ingroup c_crud */
-typedef struct MDBX_canary MDBX_canary;
-#endif
-
-/** \brief Set integers markers (aka "canary") associated with the environment.
- * \ingroup c_crud
- * \see mdbx_canary_get()
- *
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin()
- * \param [in] canary  A optional pointer to \ref MDBX_canary structure for `x`,
- *              `y` and `z` values from.
- *            - If canary is NOT NULL then the `x`, `y` and `z` values will be
- *              updated from given canary argument, but the 'v' be always set
- *              to the current transaction number if at least one `x`, `y` or
- *              `z` values have changed (i.e. if `x`, `y` and `z` have the same
- *              values as currently present then nothing will be changes or
- *              updated).
- *            - if canary is NULL then the `v` value will be explicitly update
- *              to the current transaction number without changes `x`, `y` nor
- *              `z`.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_canary_put(MDBX_txn *txn, const MDBX_canary *canary);
-
-/** \brief Returns fours integers markers (aka "canary") associated with the
- * environment.
- * \ingroup c_crud
- * \see mdbx_canary_set()
- *
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] canary  The address of an MDBX_canary structure where the
- *                     information will be copied.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_canary_get(const MDBX_txn *txn, MDBX_canary *canary);
-
-/** \brief A callback function used to compare two keys in a database
- * \ingroup c_crud
- * \see mdbx_cmp() \see mdbx_get_keycmp()
- * \see mdbx_get_datacmp \see mdbx_dcmp() */
-typedef int(MDBX_cmp_func)(const MDBX_val *a,
-                           const MDBX_val *b) MDBX_CXX17_NOEXCEPT;
-
-/** \brief Open or Create a database in the environment.
- * \ingroup c_dbi
- *
- * A database handle denotes the name and parameters of a database,
- * independently of whether such a database exists. The database handle may be
- * discarded by calling \ref mdbx_dbi_close(). The old database handle is
- * returned if the database was already open. The handle may only be closed
- * once.
- *
- * \note A notable difference between MDBX and LMDB is that MDBX make handles
- * opened for existing databases immediately available for other transactions,
- * regardless this transaction will be aborted or reset. The REASON for this is
- * to avoiding the requirement for multiple opening a same handles in
- * concurrent read transactions, and tracking of such open but hidden handles
- * until the completion of read transactions which opened them.
- *
- * Nevertheless, the handle for the NEWLY CREATED database will be invisible
- * for other transactions until the this write transaction is successfully
- * committed. If the write transaction is aborted the handle will be closed
- * automatically. After a successful commit the such handle will reside in the
- * shared environment, and may be used by other transactions.
- *
- * In contrast to LMDB, the MDBX allow this function to be called from multiple
- * concurrent transactions or threads in the same process.
- *
- * To use named database (with name != NULL), \ref mdbx_env_set_maxdbs()
- * must be called before opening the environment. Table names are
- * keys in the internal unnamed database, and may be read but not written.
- *
- * \param [in] txn    transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] name   The name of the database to open. If only a single
- *                    database is needed in the environment,
- *                    this value may be NULL.
- * \param [in] flags  Special options for this database. This parameter must
- *                    be set to 0 or by bitwise OR'ing together one or more
- *                    of the values described here:
- *  - \ref MDBX_REVERSEKEY
- *      Keys are strings to be compared in reverse order, from the end
- *      of the strings to the beginning. By default, Keys are treated as
- *      strings and compared from beginning to end.
- *  - \ref MDBX_INTEGERKEY
- *      Keys are binary integers in native byte order, either uint32_t or
- *      uint64_t, and will be sorted as such. The keys must all be of the
- *      same size and must be aligned while passing as arguments.
- *  - \ref MDBX_DUPSORT
- *      Duplicate keys may be used in the database. Or, from another point of
- *      view, keys may have multiple data items, stored in sorted order. By
- *      default keys must be unique and may have only a single data item.
- *  - \ref MDBX_DUPFIXED
- *      This flag may only be used in combination with \ref MDBX_DUPSORT. This
- *      option tells the library that the data items for this database are
- *      all the same size, which allows further optimizations in storage and
- *      retrieval. When all data items are the same size, the
- *      \ref MDBX_GET_MULTIPLE, \ref MDBX_NEXT_MULTIPLE and
- *      \ref MDBX_PREV_MULTIPLE cursor operations may be used to retrieve
- *      multiple items at once.
- *  - \ref MDBX_INTEGERDUP
- *      This option specifies that duplicate data items are binary integers,
- *      similar to \ref MDBX_INTEGERKEY keys. The data values must all be of the
- *      same size and must be aligned while passing as arguments.
- *  - \ref MDBX_REVERSEDUP
- *      This option specifies that duplicate data items should be compared as
- *      strings in reverse order (the comparison is performed in the direction
- *      from the last byte to the first).
- *  - \ref MDBX_CREATE
- *      Create the named database if it doesn't exist. This option is not
- *      allowed in a read-only transaction or a read-only environment.
- *
- * \param [out] dbi     Address where the new \ref MDBX_dbi handle
- *                      will be stored.
- *
- * For \ref mdbx_dbi_open_ex() additional arguments allow you to set custom
- * comparison functions for keys and values (for multimaps).
- * However, I recommend not using custom comparison functions, but instead
- * converting the keys to one of the forms that are suitable for built-in
- * comparators (for instance take look to the \ref value2key).
- * The reasons to not using custom comparators are:
- *   - The order of records could not be validated without your code.
- *     So `mdbx_chk` utility will reports "wrong order" errors
- *     and the `-i` option is required to ignore ones.
- *   - A records could not be ordered or sorted without your code.
- *     So mdbx_load utility should be used with `-a` option to preserve
- *     input data order.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_NOTFOUND   The specified database doesn't exist in the
- *                         environment and \ref MDBX_CREATE was not specified.
- * \retval MDBX_DBS_FULL   Too many databases have been opened.
- *                         \see mdbx_env_set_maxdbs()
- * \retval MDBX_INCOMPATIBLE  Database is incompatible with given flags,
- *                         i.e. the passed flags is different with which the
- *                         database was created, or the database was already
- *                         opened with a different comparison function(s).
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread. */
-LIBMDBX_API int mdbx_dbi_open(MDBX_txn *txn, const char *name,
-                              MDBX_db_flags_t flags, MDBX_dbi *dbi);
-
-/** \deprecated Please avoid using custom comparators
- *              and use mdbx_dbi_open() instead.
- * \ingroup c_dbi
- *
- * \param [in] txn    transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] name   The name of the database to open. If only a single
- *                    database is needed in the environment,
- *                    this value may be NULL.
- * \param [in] flags  Special options for this database.
- * \param [in] keycmp  Optional custom key comparison function for a database.
- * \param [in] datacmp Optional custom data comparison function for a database.
- * \param [out] dbi    Address where the new MDBX_dbi handle will be stored.
- * \returns A non-zero error value on failure and 0 on success. */
-MDBX_DEPRECATED LIBMDBX_API int
-mdbx_dbi_open_ex(MDBX_txn *txn, const char *name, MDBX_db_flags_t flags,
-                 MDBX_dbi *dbi, MDBX_cmp_func *keycmp, MDBX_cmp_func *datacmp);
-
-/** \defgroup value2key Value-to-Key functions to avoid custom comparators
- * \see key2value
- * @{
- *
- * The \ref mdbx_key_from_jsonInteger() build a keys which are comparable with
- * keys created by \ref mdbx_key_from_double(). So this allows mixing `int64_t`
- * and IEEE754 double values in one index for JSON-numbers with restriction for
- * integer numbers range corresponding to RFC-7159, i.e. \f$[-2^{53}+1,
- * 2^{53}-1]\f$. See bottom of page 6 at https://tools.ietf.org/html/rfc7159 */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API uint64_t
-mdbx_key_from_jsonInteger(const int64_t json_integer);
-
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API uint64_t
-mdbx_key_from_double(const double ieee754_64bit);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API uint64_t
-mdbx_key_from_ptrdouble(const double *const ieee754_64bit);
-
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API uint32_t
-mdbx_key_from_float(const float ieee754_32bit);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API uint32_t
-mdbx_key_from_ptrfloat(const float *const ieee754_32bit);
-
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_INLINE_API(uint64_t, mdbx_key_from_int64,
-                                               (const int64_t i64)) {
-  return UINT64_C(0x8000000000000000) + i64;
-}
-
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_INLINE_API(uint32_t, mdbx_key_from_int32,
-                                               (const int32_t i32)) {
-  return UINT32_C(0x80000000) + i32;
-}
-/** @} */
-
-/** \defgroup key2value Key-to-Value functions to avoid custom comparators
- * \see value2key
- * @{ */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int64_t
-mdbx_jsonInteger_from_key(const MDBX_val);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API double
-mdbx_double_from_key(const MDBX_val);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API float
-mdbx_float_from_key(const MDBX_val);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int32_t
-mdbx_int32_from_key(const MDBX_val);
-
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int64_t
-mdbx_int64_from_key(const MDBX_val);
-/** @} */
-
-/** \brief Retrieve statistics for a database.
- * \ingroup c_statinfo
- *
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi     A database handle returned by \ref mdbx_dbi_open().
- * \param [out] stat   The address of an \ref MDBX_stat structure where
- *                     the statistics will be copied.
- * \param [in] bytes   The size of \ref MDBX_stat.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL   An invalid parameter was specified. */
-LIBMDBX_API int mdbx_dbi_stat(MDBX_txn *txn, MDBX_dbi dbi, MDBX_stat *stat,
-                              size_t bytes);
-
-/** \brief Retrieve depth (bitmask) information of nested dupsort (multi-value)
- * B+trees for given database.
- * \ingroup c_statinfo
- *
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi     A database handle returned by \ref mdbx_dbi_open().
- * \param [out] mask   The address of an uint32_t value where the bitmask
- *                     will be stored.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL       An invalid parameter was specified.
- * \retval MDBX_RESULT_TRUE  The dbi isn't a dupsort (multi-value) database. */
-LIBMDBX_API int mdbx_dbi_dupsort_depthmask(MDBX_txn *txn, MDBX_dbi dbi,
-                                           uint32_t *mask);
-
-/** \brief DBI state bits returted by \ref mdbx_dbi_flags_ex()
- * \ingroup c_statinfo
- * \see mdbx_dbi_flags_ex() */
-enum MDBX_dbi_state_t {
-  /** DB was written in this txn */
-  MDBX_DBI_DIRTY = 0x01,
-  /** Named-DB record is older than txnID */
-  MDBX_DBI_STALE = 0x02,
-  /** Named-DB handle opened in this txn */
-  MDBX_DBI_FRESH = 0x04,
-  /** Named-DB handle created in this txn */
-  MDBX_DBI_CREAT = 0x08,
-};
-#ifndef __cplusplus
-/** \ingroup c_statinfo */
-typedef enum MDBX_dbi_state_t MDBX_dbi_state_t;
-#else
-DEFINE_ENUM_FLAG_OPERATORS(MDBX_dbi_state_t)
-#endif
-
-/** \brief Retrieve the DB flags and status for a database handle.
- * \ingroup c_statinfo
- *
- * \param [in] txn     A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi     A database handle returned by \ref mdbx_dbi_open().
- * \param [out] flags  Address where the flags will be returned.
- * \param [out] state  Address where the state will be returned.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_dbi_flags_ex(MDBX_txn *txn, MDBX_dbi dbi, unsigned *flags,
-                                  unsigned *state);
-/** \brief The shortcut to calling \ref mdbx_dbi_flags_ex() with `state=NULL`
- * for discarding it result. \ingroup c_statinfo */
-LIBMDBX_INLINE_API(int, mdbx_dbi_flags,
-                   (MDBX_txn * txn, MDBX_dbi dbi, unsigned *flags)) {
-  unsigned state;
-  return mdbx_dbi_flags_ex(txn, dbi, flags, &state);
-}
-
-/** \brief Close a database handle. Normally unnecessary.
- * \ingroup c_dbi
- *
- * Closing a database handle is not necessary, but lets \ref mdbx_dbi_open()
- * reuse the handle value. Usually it's better to set a bigger
- * \ref mdbx_env_set_maxdbs(), unless that value would be large.
- *
- * \note Use with care.
- * This call is synchronized via mutex with \ref mdbx_dbi_close(), but NOT with
- * other transactions running by other threads. The "next" version of libmdbx
- * (\ref MithrilDB) will solve this issue.
- *
- * Handles should only be closed if no other threads are going to reference
- * the database handle or one of its cursors any further. Do not close a handle
- * if an existing transaction has modified its database. Doing so can cause
- * misbehavior from database corruption to errors like \ref MDBX_BAD_DBI
- * (since the DB name is gone).
- *
- * \param [in] env  An environment handle returned by \ref mdbx_env_create().
- * \param [in] dbi  A database handle returned by \ref mdbx_dbi_open().
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_dbi_close(MDBX_env *env, MDBX_dbi dbi);
-
-/** \brief Empty or delete and close a database.
- * \ingroup c_crud
- *
- * \see mdbx_dbi_close() \see mdbx_dbi_open()
- *
- * \param [in] txn  A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi  A database handle returned by \ref mdbx_dbi_open().
- * \param [in] del  `false` to empty the DB, `true` to delete it
- *                  from the environment and close the DB handle.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_drop(MDBX_txn *txn, MDBX_dbi dbi, bool del);
-
-/** \brief Get items from a database.
- * \ingroup c_crud
- *
- * This function retrieves key/data pairs from the database. The address
- * and length of the data associated with the specified key are returned
- * in the structure to which data refers.
- * If the database supports duplicate keys (\ref MDBX_DUPSORT) then the
- * first data item for the key will be returned. Retrieval of other
- * items requires the use of \ref mdbx_cursor_get().
- *
- * \note The memory pointed to by the returned values is owned by the
- * database. The caller need not dispose of the memory, and may not
- * modify it in any way. For values returned in a read-only transaction
- * any modification attempts will cause a `SIGSEGV`.
- *
- * \note Values returned from the database are valid only until a
- * subsequent update operation, or the end of the transaction.
- *
- * \param [in] txn       A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi       A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key       The key to search for in the database.
- * \param [in,out] data  The data corresponding to the key.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_NOTFOUND  The key was not in the database.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_get(MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
-                         MDBX_val *data);
-
-/** \brief Get items from a database
- * and optionally number of data items for a given key.
- *
- * \ingroup c_crud
- *
- * Briefly this function does the same as \ref mdbx_get() with a few
- * differences:
- *  1. If values_count is NOT NULL, then returns the count
- *     of multi-values/duplicates for a given key.
- *  2. Updates BOTH the key and the data for pointing to the actual key-value
- *     pair inside the database.
- *
- * \param [in] txn           A transaction handle returned
- *                           by \ref mdbx_txn_begin().
- * \param [in] dbi           A database handle returned by \ref mdbx_dbi_open().
- * \param [in,out] key       The key to search for in the database.
- * \param [in,out] data      The data corresponding to the key.
- * \param [out] values_count The optional address to return number of values
- *                           associated with given key:
- *                            = 0 - in case \ref MDBX_NOTFOUND error;
- *                            = 1 - exactly for databases
- *                                  WITHOUT \ref MDBX_DUPSORT;
- *                            >= 1 for databases WITH \ref MDBX_DUPSORT.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_NOTFOUND  The key was not in the database.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_get_ex(MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key,
-                            MDBX_val *data, size_t *values_count);
-
-/** \brief Get equal or great item from a database.
- * \ingroup c_crud
- *
- * Briefly this function does the same as \ref mdbx_get() with a few
- * differences:
- * 1. Return equal or great (due comparison function) key-value
- *    pair, but not only exactly matching with the key.
- * 2. On success return \ref MDBX_SUCCESS if key found exactly,
- *    and \ref MDBX_RESULT_TRUE otherwise. Moreover, for databases with
- *    \ref MDBX_DUPSORT flag the data argument also will be used to match over
- *    multi-value/duplicates, and \ref MDBX_SUCCESS will be returned only when
- *    BOTH the key and the data match exactly.
- * 3. Updates BOTH the key and the data for pointing to the actual key-value
- *    pair inside the database.
- *
- * \param [in] txn           A transaction handle returned
- *                           by \ref mdbx_txn_begin().
- * \param [in] dbi           A database handle returned by \ref mdbx_dbi_open().
- * \param [in,out] key       The key to search for in the database.
- * \param [in,out] data      The data corresponding to the key.
- *
- * \returns A non-zero error value on failure and \ref MDBX_RESULT_FALSE
- *          or \ref MDBX_RESULT_TRUE on success (as described above).
- *          Some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_NOTFOUND      The key was not in the database.
- * \retval MDBX_EINVAL        An invalid parameter was specified. */
-LIBMDBX_API int mdbx_get_equal_or_great(MDBX_txn *txn, MDBX_dbi dbi,
-                                        MDBX_val *key, MDBX_val *data);
-
-/** \brief Store items into a database.
- * \ingroup c_crud
- *
- * This function stores key/data pairs in the database. The default behavior
- * is to enter the new key/data pair, replacing any previously existing key
- * if duplicates are disallowed, or adding a duplicate data item if
- * duplicates are allowed (see \ref MDBX_DUPSORT).
- *
- * \param [in] txn        A transaction handle returned
- *                        by \ref mdbx_txn_begin().
- * \param [in] dbi        A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key        The key to store in the database.
- * \param [in,out] data   The data to store.
- * \param [in] flags      Special options for this operation.
- *                        This parameter must be set to 0 or by bitwise OR'ing
- *                        together one or more of the values described here:
- *   - \ref MDBX_NODUPDATA
- *      Enter the new key-value pair only if it does not already appear
- *      in the database. This flag may only be specified if the database
- *      was opened with \ref MDBX_DUPSORT. The function will return
- *      \ref MDBX_KEYEXIST if the key/data pair already appears in the database.
- *
- *  - \ref MDBX_NOOVERWRITE
- *      Enter the new key/data pair only if the key does not already appear
- *      in the database. The function will return \ref MDBX_KEYEXIST if the key
- *      already appears in the database, even if the database supports
- *      duplicates (see \ref  MDBX_DUPSORT). The data parameter will be set
- *      to point to the existing item.
- *
- *  - \ref MDBX_CURRENT
- *      Update an single existing entry, but not add new ones. The function will
- *      return \ref MDBX_NOTFOUND if the given key not exist in the database.
- *      In case multi-values for the given key, with combination of
- *      the \ref MDBX_ALLDUPS will replace all multi-values,
- *      otherwise return the \ref MDBX_EMULTIVAL.
- *
- *  - \ref MDBX_RESERVE
- *      Reserve space for data of the given size, but don't copy the given
- *      data. Instead, return a pointer to the reserved space, which the
- *      caller can fill in later - before the next update operation or the
- *      transaction ends. This saves an extra memcpy if the data is being
- *      generated later. MDBX does nothing else with this memory, the caller
- *      is expected to modify all of the space requested. This flag must not
- *      be specified if the database was opened with \ref MDBX_DUPSORT.
- *
- *  - \ref MDBX_APPEND
- *      Append the given key/data pair to the end of the database. This option
- *      allows fast bulk loading when keys are already known to be in the
- *      correct order. Loading unsorted keys with this flag will cause
- *      a \ref MDBX_EKEYMISMATCH error.
- *
- *  - \ref MDBX_APPENDDUP
- *      As above, but for sorted dup data.
- *
- *  - \ref MDBX_MULTIPLE
- *      Store multiple contiguous data elements in a single request. This flag
- *      may only be specified if the database was opened with
- *      \ref MDBX_DUPFIXED. With combination the \ref MDBX_ALLDUPS
- *      will replace all multi-values.
- *      The data argument must be an array of two \ref MDBX_val. The `iov_len`
- *      of the first \ref MDBX_val must be the size of a single data element.
- *      The `iov_base` of the first \ref MDBX_val must point to the beginning
- *      of the array of contiguous data elements which must be properly aligned
- *      in case of database with \ref MDBX_INTEGERDUP flag.
- *      The `iov_len` of the second \ref MDBX_val must be the count of the
- *      number of data elements to store. On return this field will be set to
- *      the count of the number of elements actually written. The `iov_base` of
- *      the second \ref MDBX_val is unused.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_KEYEXIST  The key/value pair already exists in the database.
- * \retval MDBX_MAP_FULL  The database is full, see \ref mdbx_env_set_mapsize().
- * \retval MDBX_TXN_FULL  The transaction has too many dirty pages.
- * \retval MDBX_EACCES    An attempt was made to write
- *                        in a read-only transaction.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_put(MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
-                         MDBX_val *data, MDBX_put_flags_t flags);
-
-/** \brief Replace items in a database.
- * \ingroup c_crud
- *
- * This function allows to update or delete an existing value at the same time
- * as the previous value is retrieved. If the argument new_data equal is NULL
- * zero, the removal is performed, otherwise the update/insert.
- *
- * The current value may be in an already changed (aka dirty) page. In this
- * case, the page will be overwritten during the update, and the old value will
- * be lost. Therefore, an additional buffer must be passed via old_data
- * argument initially to copy the old value. If the buffer passed in is too
- * small, the function will return \ref MDBX_RESULT_TRUE by setting iov_len
- * field pointed by old_data argument to the appropriate value, without
- * performing any changes.
- *
- * For databases with non-unique keys (i.e. with \ref MDBX_DUPSORT flag),
- * another use case is also possible, when by old_data argument selects a
- * specific item from multi-value/duplicates with the same key for deletion or
- * update. To select this scenario in flags should simultaneously specify
- * \ref MDBX_CURRENT and \ref MDBX_NOOVERWRITE. This combination is chosen
- * because it makes no sense, and thus allows you to identify the request of
- * such a scenario.
- *
- * \param [in] txn           A transaction handle returned
- *                           by \ref mdbx_txn_begin().
- * \param [in] dbi           A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key           The key to store in the database.
- * \param [in] new_data      The data to store, if NULL then deletion will
- *                           be performed.
- * \param [in,out] old_data  The buffer for retrieve previous value as describe
- *                           above.
- * \param [in] flags         Special options for this operation.
- *                           This parameter must be set to 0 or by bitwise
- *                           OR'ing together one or more of the values
- *                           described in \ref mdbx_put() description above,
- *                           and additionally
- *                           (\ref MDBX_CURRENT | \ref MDBX_NOOVERWRITE)
- *                           combination for selection particular item from
- *                           multi-value/duplicates.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_replace(MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
-                             MDBX_val *new_data, MDBX_val *old_data,
-                             MDBX_put_flags_t flags);
-
-typedef int (*MDBX_preserve_func)(void *context, MDBX_val *target,
-                                  const void *src, size_t bytes);
-LIBMDBX_API int mdbx_replace_ex(MDBX_txn *txn, MDBX_dbi dbi,
-                                const MDBX_val *key, MDBX_val *new_data,
-                                MDBX_val *old_data, MDBX_put_flags_t flags,
-                                MDBX_preserve_func preserver,
-                                void *preserver_context);
-
-/** \brief Delete items from a database.
- * \ingroup c_crud
- *
- * This function removes key/data pairs from the database.
- *
- * \note The data parameter is NOT ignored regardless the database does
- * support sorted duplicate data items or not. If the data parameter
- * is non-NULL only the matching data item will be deleted. Otherwise, if data
- * parameter is NULL, any/all value(s) for specified key will be deleted.
- *
- * This function will return \ref MDBX_NOTFOUND if the specified key/data
- * pair is not in the database.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \param [in] txn   A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi   A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key   The key to delete from the database.
- * \param [in] data  The data to delete.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EACCES   An attempt was made to write
- *                       in a read-only transaction.
- * \retval MDBX_EINVAL   An invalid parameter was specified. */
-LIBMDBX_API int mdbx_del(MDBX_txn *txn, MDBX_dbi dbi, const MDBX_val *key,
-                         const MDBX_val *data);
-
-/** \brief Create a cursor handle but not bind it to transaction nor DBI handle.
- * \ingroup c_cursors
- *
- * An capable of operation cursor is associated with a specific transaction and
- * database. A cursor cannot be used when its database handle is closed. Nor
- * when its transaction has ended, except with \ref mdbx_cursor_bind() and
- * \ref mdbx_cursor_renew().
- * Also it can be discarded with \ref mdbx_cursor_close().
- *
- * A cursor must be closed explicitly always, before or after its transaction
- * ends. It can be reused with \ref mdbx_cursor_bind()
- * or \ref mdbx_cursor_renew() before finally closing it.
- *
- * \note In contrast to LMDB, the MDBX required that any opened cursors can be
- * reused and must be freed explicitly, regardless ones was opened in a
- * read-only or write transaction. The REASON for this is eliminates ambiguity
- * which helps to avoid errors such as: use-after-free, double-free, i.e.
- * memory corruption and segfaults.
- *
- * \param [in] context A pointer to application context to be associated with
- *                     created cursor and could be retrieved by
- *                     \ref mdbx_cursor_get_userctx() until cursor closed.
- *
- * \returns Created cursor handle or NULL in case out of memory. */
-LIBMDBX_API MDBX_cursor *mdbx_cursor_create(void *context);
-
-/** \brief Set application information associated with the \ref MDBX_cursor.
- * \ingroup c_cursors
- * \see mdbx_cursor_get_userctx()
- *
- * \param [in] cursor  An cursor handle returned by \ref mdbx_cursor_create()
- *                     or \ref mdbx_cursor_open().
- * \param [in] ctx     An arbitrary pointer for whatever the application needs.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_cursor_set_userctx(MDBX_cursor *cursor, void *ctx);
-
-/** \brief Get the application information associated with the MDBX_cursor.
- * \ingroup c_cursors
- * \see mdbx_cursor_set_userctx()
- *
- * \param [in] cursor  An cursor handle returned by \ref mdbx_cursor_create()
- *                     or \ref mdbx_cursor_open().
- * \returns The pointer which was passed via the `context` parameter
- *          of `mdbx_cursor_create()` or set by \ref mdbx_cursor_set_userctx(),
- *          or `NULL` if something wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API void *
-mdbx_cursor_get_userctx(const MDBX_cursor *cursor);
-
-/** \brief Bind cursor to specified transaction and DBI handle.
- * \ingroup c_cursors
- *
- * Using of the `mdbx_cursor_bind()` is equivalent to calling
- * \ref mdbx_cursor_renew() but with specifying an arbitrary dbi handle.
- *
- * An capable of operation cursor is associated with a specific transaction and
- * database. The cursor may be associated with a new transaction,
- * and referencing a new or the same database handle as it was created with.
- * This may be done whether the previous transaction is live or dead.
- *
- * \note In contrast to LMDB, the MDBX required that any opened cursors can be
- * reused and must be freed explicitly, regardless ones was opened in a
- * read-only or write transaction. The REASON for this is eliminates ambiguity
- * which helps to avoid errors such as: use-after-free, double-free, i.e.
- * memory corruption and segfaults.
- *
- * \param [in] txn      A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi      A database handle returned by \ref mdbx_dbi_open().
- * \param [out] cursor  A cursor handle returned by \ref mdbx_cursor_create().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_bind(MDBX_txn *txn, MDBX_cursor *cursor,
-                                 MDBX_dbi dbi);
-
-/** \brief Create a cursor handle for the specified transaction and DBI handle.
- * \ingroup c_cursors
- *
- * Using of the `mdbx_cursor_open()` is equivalent to calling
- * \ref mdbx_cursor_create() and then \ref mdbx_cursor_bind() functions.
- *
- * An capable of operation cursor is associated with a specific transaction and
- * database. A cursor cannot be used when its database handle is closed. Nor
- * when its transaction has ended, except with \ref mdbx_cursor_bind() and
- * \ref mdbx_cursor_renew().
- * Also it can be discarded with \ref mdbx_cursor_close().
- *
- * A cursor must be closed explicitly always, before or after its transaction
- * ends. It can be reused with \ref mdbx_cursor_bind()
- * or \ref mdbx_cursor_renew() before finally closing it.
- *
- * \note In contrast to LMDB, the MDBX required that any opened cursors can be
- * reused and must be freed explicitly, regardless ones was opened in a
- * read-only or write transaction. The REASON for this is eliminates ambiguity
- * which helps to avoid errors such as: use-after-free, double-free, i.e.
- * memory corruption and segfaults.
- *
- * \param [in] txn      A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi      A database handle returned by \ref mdbx_dbi_open().
- * \param [out] cursor  Address where the new \ref MDBX_cursor handle will be
- *                      stored.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_open(MDBX_txn *txn, MDBX_dbi dbi,
-                                 MDBX_cursor **cursor);
-
-/** \brief Close a cursor handle.
- * \ingroup c_cursors
- *
- * The cursor handle will be freed and must not be used again after this call,
- * but its transaction may still be live.
- *
- * \note In contrast to LMDB, the MDBX required that any opened cursors can be
- * reused and must be freed explicitly, regardless ones was opened in a
- * read-only or write transaction. The REASON for this is eliminates ambiguity
- * which helps to avoid errors such as: use-after-free, double-free, i.e.
- * memory corruption and segfaults.
- *
- * \param [in] cursor  A cursor handle returned by \ref mdbx_cursor_open()
- *                     or \ref mdbx_cursor_create(). */
-LIBMDBX_API void mdbx_cursor_close(MDBX_cursor *cursor);
-
-/** \brief Renew a cursor handle.
- * \ingroup c_cursors
- *
- * An capable of operation cursor is associated with a specific transaction and
- * database. The cursor may be associated with a new transaction,
- * and referencing a new or the same database handle as it was created with.
- * This may be done whether the previous transaction is live or dead.
- *
- * Using of the `mdbx_cursor_renew()` is equivalent to calling
- * \ref mdbx_cursor_bind() with the DBI handle that previously
- * the cursor was used with.
- *
- * \note In contrast to LMDB, the MDBX allow any cursor to be re-used by using
- * \ref mdbx_cursor_renew(), to avoid unnecessary malloc/free overhead until it
- * freed by \ref mdbx_cursor_close().
- *
- * \param [in] txn      A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] cursor   A cursor handle returned by \ref mdbx_cursor_open().
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL  An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_renew(MDBX_txn *txn, MDBX_cursor *cursor);
-
-/** \brief Return the cursor's transaction handle.
- * \ingroup c_cursors
- *
- * \param [in] cursor A cursor handle returned by \ref mdbx_cursor_open(). */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API MDBX_txn *
-mdbx_cursor_txn(const MDBX_cursor *cursor);
-
-/** \brief Return the cursor's database handle.
- * \ingroup c_cursors
- *
- * \param [in] cursor  A cursor handle returned by \ref mdbx_cursor_open(). */
-LIBMDBX_API MDBX_dbi mdbx_cursor_dbi(const MDBX_cursor *cursor);
-
-/** \brief Copy cursor position and state.
- * \ingroup c_cursors
- *
- * \param [in] src       A source cursor handle returned
- * by \ref mdbx_cursor_create() or \ref mdbx_cursor_open().
- *
- * \param [in,out] dest  A destination cursor handle returned
- * by \ref mdbx_cursor_create() or \ref mdbx_cursor_open().
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_cursor_copy(const MDBX_cursor *src, MDBX_cursor *dest);
-
-/** \brief Retrieve by cursor.
- * \ingroup c_cursors c_crud
- *
- * This function retrieves key/data pairs from the database. The address and
- * length of the key are returned in the object to which key refers (except
- * for the case of the \ref MDBX_SET option, in which the key object is
- * unchanged), and the address and length of the data are returned in the object
- * to which data refers.
- * \see mdbx_get()
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- * \param [in,out] key   The key for a retrieved item.
- * \param [in,out] data  The data of a retrieved item.
- * \param [in] op        A cursor operation \ref MDBX_cursor_op.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_NOTFOUND  No matching key found.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_get(MDBX_cursor *cursor, MDBX_val *key,
-                                MDBX_val *data, MDBX_cursor_op op);
-
-/** \brief Store by cursor.
- * \ingroup c_cursors c_crud
- *
- * This function stores key/data pairs into the database. The cursor is
- * positioned at the new item, or on failure usually near it.
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- * \param [in] key       The key operated on.
- * \param [in,out] data  The data operated on.
- * \param [in] flags     Options for this operation. This parameter
- *                       must be set to 0 or by bitwise OR'ing together
- *                       one or more of the values described here:
- *  - \ref MDBX_CURRENT
- *      Replace the item at the current cursor position. The key parameter
- *      must still be provided, and must match it, otherwise the function
- *      return \ref MDBX_EKEYMISMATCH. With combination the
- *      \ref MDBX_ALLDUPS will replace all multi-values.
- *
- *      \note MDBX allows (unlike LMDB) you to change the size of the data and
- *      automatically handles reordering for sorted duplicates
- *      (see \ref MDBX_DUPSORT).
- *
- *  - \ref MDBX_NODUPDATA
- *      Enter the new key-value pair only if it does not already appear in the
- *      database. This flag may only be specified if the database was opened
- *      with \ref MDBX_DUPSORT. The function will return \ref MDBX_KEYEXIST
- *      if the key/data pair already appears in the database.
- *
- *  - \ref MDBX_NOOVERWRITE
- *      Enter the new key/data pair only if the key does not already appear
- *      in the database. The function will return \ref MDBX_KEYEXIST if the key
- *      already appears in the database, even if the database supports
- *      duplicates (\ref MDBX_DUPSORT).
- *
- *  - \ref MDBX_RESERVE
- *      Reserve space for data of the given size, but don't copy the given
- *      data. Instead, return a pointer to the reserved space, which the
- *      caller can fill in later - before the next update operation or the
- *      transaction ends. This saves an extra memcpy if the data is being
- *      generated later. This flag must not be specified if the database
- *      was opened with \ref MDBX_DUPSORT.
- *
- *  - \ref MDBX_APPEND
- *      Append the given key/data pair to the end of the database. No key
- *      comparisons are performed. This option allows fast bulk loading when
- *      keys are already known to be in the correct order. Loading unsorted
- *      keys with this flag will cause a \ref MDBX_KEYEXIST error.
- *
- *  - \ref MDBX_APPENDDUP
- *      As above, but for sorted dup data.
- *
- *  - \ref MDBX_MULTIPLE
- *      Store multiple contiguous data elements in a single request. This flag
- *      may only be specified if the database was opened with
- *      \ref MDBX_DUPFIXED. With combination the \ref MDBX_ALLDUPS
- *      will replace all multi-values.
- *      The data argument must be an array of two \ref MDBX_val. The `iov_len`
- *      of the first \ref MDBX_val must be the size of a single data element.
- *      The `iov_base` of the first \ref MDBX_val must point to the beginning
- *      of the array of contiguous data elements which must be properly aligned
- *      in case of database with \ref MDBX_INTEGERDUP flag.
- *      The `iov_len` of the second \ref MDBX_val must be the count of the
- *      number of data elements to store. On return this field will be set to
- *      the count of the number of elements actually written. The `iov_base` of
- *      the second \ref MDBX_val is unused.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EKEYMISMATCH  The given key value is mismatched to the current
- *                            cursor position
- * \retval MDBX_MAP_FULL      The database is full,
- *                             see \ref mdbx_env_set_mapsize().
- * \retval MDBX_TXN_FULL      The transaction has too many dirty pages.
- * \retval MDBX_EACCES        An attempt was made to write in a read-only
- *                            transaction.
- * \retval MDBX_EINVAL        An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_put(MDBX_cursor *cursor, const MDBX_val *key,
-                                MDBX_val *data, MDBX_put_flags_t flags);
-
-/** \brief Delete current key/data pair.
- * \ingroup c_cursors c_crud
- *
- * This function deletes the key/data pair to which the cursor refers. This
- * does not invalidate the cursor, so operations such as \ref MDBX_NEXT can
- * still be used on it. Both \ref MDBX_NEXT and \ref MDBX_GET_CURRENT will
- * return the same record after this operation.
- *
- * \param [in] cursor  A cursor handle returned by mdbx_cursor_open().
- * \param [in] flags   Options for this operation. This parameter must be set
- * to one of the values described here.
- *
- *  - \ref MDBX_CURRENT Delete only single entry at current cursor position.
- *  - \ref MDBX_ALLDUPS
- *    or \ref MDBX_NODUPDATA (supported for compatibility)
- *      Delete all of the data items for the current key. This flag has effect
- *      only for database(s) was created with \ref MDBX_DUPSORT.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_MAP_FULL      The database is full,
- *                            see \ref mdbx_env_set_mapsize().
- * \retval MDBX_TXN_FULL      The transaction has too many dirty pages.
- * \retval MDBX_EACCES        An attempt was made to write in a read-only
- *                            transaction.
- * \retval MDBX_EINVAL        An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_del(MDBX_cursor *cursor, MDBX_put_flags_t flags);
-
-/** \brief Return count of duplicates for current key.
- * \ingroup c_cursors c_crud
- *
- * This call is valid for all databases, but reasonable only for that support
- * sorted duplicate data items \ref MDBX_DUPSORT.
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- * \param [out] pcount   Address where the count will be stored.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_THREAD_MISMATCH  Given transaction is not owned
- *                               by current thread.
- * \retval MDBX_EINVAL   Cursor is not initialized, or an invalid parameter
- *                       was specified. */
-LIBMDBX_API int mdbx_cursor_count(const MDBX_cursor *cursor, size_t *pcount);
-
-/** \brief Determines whether the cursor is pointed to a key-value pair or not,
- * i.e. was not positioned or points to the end of data.
- * \ingroup c_cursors
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- *
- * \returns A \ref MDBX_RESULT_TRUE or \ref MDBX_RESULT_FALSE value,
- *          otherwise the error code:
- * \retval MDBX_RESULT_TRUE    No more data available or cursor not
- *                             positioned
- * \retval MDBX_RESULT_FALSE   A data is available
- * \retval Otherwise the error code */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int
-mdbx_cursor_eof(const MDBX_cursor *cursor);
-
-/** \brief Determines whether the cursor is pointed to the first key-value pair
- * or not. \ingroup c_cursors
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- *
- * \returns A MDBX_RESULT_TRUE or MDBX_RESULT_FALSE value,
- *          otherwise the error code:
- * \retval MDBX_RESULT_TRUE   Cursor positioned to the first key-value pair
- * \retval MDBX_RESULT_FALSE  Cursor NOT positioned to the first key-value
- * pair \retval Otherwise the error code */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int
-mdbx_cursor_on_first(const MDBX_cursor *cursor);
-
-/** \brief Determines whether the cursor is pointed to the last key-value pair
- * or not. \ingroup c_cursors
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- *
- * \returns A \ref MDBX_RESULT_TRUE or \ref MDBX_RESULT_FALSE value,
- *          otherwise the error code:
- * \retval MDBX_RESULT_TRUE   Cursor positioned to the last key-value pair
- * \retval MDBX_RESULT_FALSE  Cursor NOT positioned to the last key-value pair
- * \retval Otherwise the error code */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int
-mdbx_cursor_on_last(const MDBX_cursor *cursor);
-
-/** \addtogroup c_rqest
- * \details \note The estimation result varies greatly depending on the filling
- * of specific pages and the overall balance of the b-tree:
- *
- * 1. The number of items is estimated by analyzing the height and fullness of
- * the b-tree. The accuracy of the result directly depends on the balance of
- * the b-tree, which in turn is determined by the history of previous
- * insert/delete operations and the nature of the data (i.e. variability of
- * keys length and so on). Therefore, the accuracy of the estimation can vary
- * greatly in a particular situation.
- *
- * 2. To understand the potential spread of results, you should consider a
- * possible situations basing on the general criteria for splitting and merging
- * b-tree pages:
- *  - the page is split into two when there is no space for added data;
- *  - two pages merge if the result fits in half a page;
- *  - thus, the b-tree can consist of an arbitrary combination of pages filled
- *    both completely and only 1/4. Therefore, in the worst case, the result
- *    can diverge 4 times for each level of the b-tree excepting the first and
- *    the last.
- *
- * 3. In practice, the probability of extreme cases of the above situation is
- * close to zero and in most cases the error does not exceed a few percent. On
- * the other hand, it's just a chance you shouldn't overestimate. */
-
-/** \brief Estimates the distance between cursors as a number of elements.
- * \ingroup c_rqest
- *
- * This function performs a rough estimate based only on b-tree pages that are
- * common for the both cursor's stacks. The results of such estimation can be
- * used to build and/or optimize query execution plans.
- *
- * Please see notes on accuracy of the result in the details
- * of \ref c_rqest section.
- *
- * Both cursors must be initialized for the same database and the same
- * transaction.
- *
- * \param [in] first            The first cursor for estimation.
- * \param [in] last             The second cursor for estimation.
- * \param [out] distance_items  The pointer to store estimated distance value,
- *                              i.e. `*distance_items = distance(first, last)`.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_estimate_distance(const MDBX_cursor *first,
-                                       const MDBX_cursor *last,
-                                       ptrdiff_t *distance_items);
-
-/** \brief Estimates the move distance.
- * \ingroup c_rqest
- *
- * This function performs a rough estimate distance between the current
- * cursor position and next position after the specified move-operation with
- * given key and data. The results of such estimation can be used to build
- * and/or optimize query execution plans. Current cursor position and state are
- * preserved.
- *
- * Please see notes on accuracy of the result in the details
- * of \ref c_rqest section.
- *
- * \param [in] cursor            Cursor for estimation.
- * \param [in,out] key           The key for a retrieved item.
- * \param [in,out] data          The data of a retrieved item.
- * \param [in] move_op           A cursor operation \ref MDBX_cursor_op.
- * \param [out] distance_items   A pointer to store estimated move distance
- *                               as the number of elements.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_estimate_move(const MDBX_cursor *cursor, MDBX_val *key,
-                                   MDBX_val *data, MDBX_cursor_op move_op,
-                                   ptrdiff_t *distance_items);
-
-/** \brief Estimates the size of a range as a number of elements.
- * \ingroup c_rqest
- *
- * The results of such estimation can be used to build and/or optimize query
- * execution plans.
- *
- * Please see notes on accuracy of the result in the details
- * of \ref c_rqest section.
- *
- *
- * \param [in] txn        A transaction handle returned
- *                        by \ref mdbx_txn_begin().
- * \param [in] dbi        A database handle returned by  \ref mdbx_dbi_open().
- * \param [in] begin_key  The key of range beginning or NULL for explicit FIRST.
- * \param [in] begin_data Optional additional data to seeking among sorted
- *                        duplicates.
- *                        Only for \ref MDBX_DUPSORT, NULL otherwise.
- * \param [in] end_key    The key of range ending or NULL for explicit LAST.
- * \param [in] end_data   Optional additional data to seeking among sorted
- *                        duplicates.
- *                        Only for \ref MDBX_DUPSORT, NULL otherwise.
- * \param [out] distance_items  A pointer to store range estimation result.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_estimate_range(MDBX_txn *txn, MDBX_dbi dbi,
-                                    MDBX_val *begin_key, MDBX_val *begin_data,
-                                    MDBX_val *end_key, MDBX_val *end_data,
-                                    ptrdiff_t *distance_items);
-
-/** \brief The EPSILON value for mdbx_estimate_range()
- * \ingroup c_rqest */
-#define MDBX_EPSILON ((MDBX_val *)((ptrdiff_t)-1))
-
-/** \brief Determines whether the given address is on a dirty database page of
- * the transaction or not. \ingroup c_statinfo
- *
- * Ultimately, this allows to avoid copy data from non-dirty pages.
- *
- * "Dirty" pages are those that have already been changed during a write
- * transaction. Accordingly, any further changes may result in such pages being
- * overwritten. Therefore, all functions libmdbx performing changes inside the
- * database as arguments should NOT get pointers to data in those pages. In
- * turn, "not dirty" pages before modification will be copied.
- *
- * In other words, data from dirty pages must either be copied before being
- * passed as arguments for further processing or rejected at the argument
- * validation stage. Thus, `mdbx_is_dirty()` allows you to get rid of
- * unnecessary copying, and perform a more complete check of the arguments.
- *
- * \note The address passed must point to the beginning of the data. This is
- * the only way to ensure that the actual page header is physically located in
- * the same memory page, including for multi-pages with long data.
- *
- * \note In rare cases the function may return a false positive answer
- * (\ref MDBX_RESULT_TRUE when data is NOT on a dirty page), but never a false
- * negative if the arguments are correct.
- *
- * \param [in] txn      A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] ptr      The address of data to check.
- *
- * \returns A MDBX_RESULT_TRUE or MDBX_RESULT_FALSE value,
- *          otherwise the error code:
- * \retval MDBX_RESULT_TRUE    Given address is on the dirty page.
- * \retval MDBX_RESULT_FALSE   Given address is NOT on the dirty page.
- * \retval Otherwise the error code. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int mdbx_is_dirty(const MDBX_txn *txn,
-                                                         const void *ptr);
-
-/** \brief Sequence generation for a database.
- * \ingroup c_crud
- *
- * The function allows to create a linear sequence of unique positive integers
- * for each database. The function can be called for a read transaction to
- * retrieve the current sequence value, and the increment must be zero.
- * Sequence changes become visible outside the current write transaction after
- * it is committed, and discarded on abort.
- *
- * \param [in] txn        A transaction handle returned
- *                        by \ref mdbx_txn_begin().
- * \param [in] dbi        A database handle returned by \ref mdbx_dbi_open().
- * \param [out] result    The optional address where the value of sequence
- *                        before the change will be stored.
- * \param [in] increment  Value to increase the sequence,
- *                        must be 0 for read-only transactions.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_RESULT_TRUE   Increasing the sequence has resulted in an
- *                            overflow and therefore cannot be executed. */
-LIBMDBX_API int mdbx_dbi_sequence(MDBX_txn *txn, MDBX_dbi dbi, uint64_t *result,
-                                  uint64_t increment);
-
-/** \brief Compare two keys according to a particular database.
- * \ingroup c_crud
- *
- * This returns a comparison as if the two data items were keys in the
- * specified database.
- *
- * \warning There ss a Undefined behavior if one of arguments is invalid.
- *
- * \param [in] txn   A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi   A database handle returned by \ref mdbx_dbi_open().
- * \param [in] a     The first item to compare.
- * \param [in] b     The second item to compare.
- *
- * \returns < 0 if a < b, 0 if a == b, > 0 if a > b */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int mdbx_cmp(const MDBX_txn *txn,
-                                                    MDBX_dbi dbi,
-                                                    const MDBX_val *a,
-                                                    const MDBX_val *b);
-
-/** \brief Returns default internal key's comparator for given database flags.
- * \ingroup c_extra */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API MDBX_cmp_func *
-mdbx_get_keycmp(MDBX_db_flags_t flags);
-
-/** \brief Compare two data items according to a particular database.
- * \ingroup c_crud
- *
- * This returns a comparison as if the two items were data items of the
- * specified database.
- *
- * \warning There ss a Undefined behavior if one of arguments is invalid.
- *
- * \param [in] txn   A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi   A database handle returned by \ref mdbx_dbi_open().
- * \param [in] a     The first item to compare.
- * \param [in] b     The second item to compare.
- *
- * \returns < 0 if a < b, 0 if a == b, > 0 if a > b */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API int mdbx_dcmp(const MDBX_txn *txn,
-                                                     MDBX_dbi dbi,
-                                                     const MDBX_val *a,
-                                                     const MDBX_val *b);
-
-/** \brief Returns default internal data's comparator for given database flags
- * \ingroup c_extra */
-MDBX_NOTHROW_CONST_FUNCTION LIBMDBX_API MDBX_cmp_func *
-mdbx_get_datacmp(MDBX_db_flags_t flags);
-
-/** \brief A callback function used to enumerate the reader lock table.
- * \ingroup c_statinfo
- *
- * \param [in] ctx           An arbitrary context pointer for the callback.
- * \param [in] num           The serial number during enumeration,
- *                           starting from 1.
- * \param [in] slot          The reader lock table slot number.
- * \param [in] txnid         The ID of the transaction being read,
- *                           i.e. the MVCC-snapshot number.
- * \param [in] lag           The lag from a recent MVCC-snapshot,
- *                           i.e. the number of committed write transactions
- *                           since the current read transaction started.
- * \param [in] pid           The reader process ID.
- * \param [in] thread        The reader thread ID.
- * \param [in] bytes_used    The number of last used page in the MVCC-snapshot
- *                           which being read,
- *                           i.e. database file can't shrinked beyond this.
- * \param [in] bytes_retired The total size of the database pages that were
- *                           retired by committed write transactions after
- *                           the reader's MVCC-snapshot,
- *                           i.e. the space which would be freed after
- *                           the Reader releases the MVCC-snapshot
- *                           for reuse by completion read transaction.
- *
- * \returns < 0 on failure, >= 0 on success. \see mdbx_reader_list() */
-typedef int(MDBX_reader_list_func)(void *ctx, int num, int slot, mdbx_pid_t pid,
-                                   mdbx_tid_t thread, uint64_t txnid,
-                                   uint64_t lag, size_t bytes_used,
-                                   size_t bytes_retained) MDBX_CXX17_NOEXCEPT;
-
-/** \brief Enumerate the entries in the reader lock table.
- *
- * \ingroup c_statinfo
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- * \param [in] func    A \ref MDBX_reader_list_func function.
- * \param [in] ctx     An arbitrary context pointer for the enumeration
- *                     function.
- *
- * \returns A non-zero error value on failure and 0 on success,
- * or \ref MDBX_RESULT_TRUE if the reader lock table is empty. */
-LIBMDBX_API int mdbx_reader_list(const MDBX_env *env,
-                                 MDBX_reader_list_func *func, void *ctx);
-
-/** \brief Check for stale entries in the reader lock table.
- * \ingroup c_extra
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- * \param [out] dead   Number of stale slots that were cleared.
- *
- * \returns A non-zero error value on failure and 0 on success,
- * or \ref MDBX_RESULT_TRUE if a dead reader(s) found or mutex was recovered. */
-LIBMDBX_API int mdbx_reader_check(MDBX_env *env, int *dead);
-
-/** \brief Returns a lag of the reading for the given transaction.
- * \ingroup c_statinfo
- *
- * Returns an information for estimate how much given read-only
- * transaction is lagging relative the to actual head.
- * \deprecated Please use \ref mdbx_txn_info() instead.
- *
- * \param [in] txn       A transaction handle returned by \ref mdbx_txn_begin().
- * \param [out] percent  Percentage of page allocation in the database.
- *
- * \returns Number of transactions committed after the given was started for
- *          read, or negative value on failure. */
-MDBX_DEPRECATED LIBMDBX_API int mdbx_txn_straggler(const MDBX_txn *txn,
-                                                   int *percent);
-
-/** \brief Registers the current thread as a reader for the environment.
- * \ingroup c_extra
- *
- * To perform read operations without blocking, a reader slot must be assigned
- * for each thread. However, this assignment requires a short-term lock
- * acquisition which is performed automatically. This function allows you to
- * assign the reader slot in advance and thus avoid capturing the blocker when
- * the read transaction starts firstly from current thread.
- * \see mdbx_thread_unregister()
- *
- * \note Threads are registered automatically the first time a read transaction
- *       starts. Therefore, there is no need to use this function, except in
- *       special cases.
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- *
- * \returns A non-zero error value on failure and 0 on success,
- * or \ref MDBX_RESULT_TRUE if thread is already registered. */
-LIBMDBX_API int mdbx_thread_register(const MDBX_env *env);
-
-/** \brief Unregisters the current thread as a reader for the environment.
- * \ingroup c_extra
- *
- * To perform read operations without blocking, a reader slot must be assigned
- * for each thread. However, the assigned reader slot will remain occupied until
- * the thread ends or the environment closes. This function allows you to
- * explicitly release the assigned reader slot.
- * \see mdbx_thread_register()
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- *
- * \returns A non-zero error value on failure and 0 on success, or
- * \ref MDBX_RESULT_TRUE if thread is not registered or already unregistered. */
-LIBMDBX_API int mdbx_thread_unregister(const MDBX_env *env);
-
-/** \brief A Handle-Slow-Readers callback function to resolve database
- * full/overflow issue due to a reader(s) which prevents the old data from being
- * recycled.
- * \ingroup c_err
- *
- * Read transactions prevent reuse of pages freed by newer write transactions,
- * thus the database can grow quickly. This callback will be called when there
- * is not enough space in the database (i.e. before increasing the database size
- * or before \ref MDBX_MAP_FULL error) and thus can be used to resolve issues
- * with a "long-lived" read transactions.
- * \see long-lived-read
- *
- * Using this callback you can choose how to resolve the situation:
- *   - abort the write transaction with an error;
- *   - wait for the read transaction(s) to complete;
- *   - notify a thread performing a long-lived read transaction
- *     and wait for an effect;
- *   - kill the thread or whole process that performs the long-lived read
- *     transaction;
- *
- * Depending on the arguments and needs, your implementation may wait,
- * terminate a process or thread that is performing a long read, or perform
- * some other action. In doing so it is important that the returned code always
- * corresponds to the performed action.
- *
- * \param [in] env     An environment handle returned by \ref mdbx_env_create().
- * \param [in] txn     The current write transaction which internally at
- *                     the \ref MDBX_MAP_FULL condition.
- * \param [in] pid     A pid of the reader process.
- * \param [in] tid     A thread_id of the reader thread.
- * \param [in] laggard An oldest read transaction number on which stalled.
- * \param [in] gap     A lag from the last committed txn.
- * \param [in] space   A space that actually become available for reuse after
- *                     this reader finished. The callback function can take
- *                     this value into account to evaluate the impact that
- *                     a long-running transaction has.
- * \param [in] retry   A retry number starting from 0.
- *                     If callback has returned 0 at least once, then at end
- *                     of current handling loop the callback function will be
- *                     called additionally with negative value to notify about
- *                     the end of loop. The callback function can use this value
- *                     to implement timeout logic while waiting for readers.
- *
- * \returns The RETURN CODE determines the further actions libmdbx and must
- *          match the action which was executed by the callback:
- *
- * \retval -2 or less  An error condition and the reader was not killed.
- *
- * \retval -1          The callback was unable to solve the problem and
- *                     agreed on \ref MDBX_MAP_FULL error;
- *                     libmdbx should increase the database size or
- *                     return \ref MDBX_MAP_FULL error.
- *
- * \retval 0 (zero)    The callback solved the problem or just waited for
- *                     a while, libmdbx should rescan the reader lock table and
- *                     retry. This also includes a situation when corresponding
- *                     transaction terminated in normal way by
- *                     \ref mdbx_txn_abort() or \ref mdbx_txn_reset(),
- *                     and my be restarted. I.e. reader slot don't needed
- *                     to be cleaned from transaction.
- *
- * \retval 1           Transaction aborted asynchronous and reader slot
- *                     should be cleared immediately, i.e. read transaction
- *                     will not continue but \ref mdbx_txn_abort()
- *                     or \ref mdbx_txn_reset() will be called later.
- *
- * \retval 2 or great  The reader process was terminated or killed,
- *                     and libmdbx should entirely reset reader registration.
- *
- * \see mdbx_env_set_hsr() \see mdbx_env_get_hsr()
- */
-typedef int(MDBX_hsr_func)(const MDBX_env *env, const MDBX_txn *txn,
-                           mdbx_pid_t pid, mdbx_tid_t tid, uint64_t laggard,
-                           unsigned gap, size_t space,
-                           int retry) MDBX_CXX17_NOEXCEPT;
-
-/** \brief Sets a Handle-Slow-Readers callback to resolve database full/overflow
- * issue due to a reader(s) which prevents the old data from being recycled.
- * \ingroup c_err
- *
- * The callback will only be triggered when the database is full due to a
- * reader(s) prevents the old data from being recycled.
- *
- * \see mdbx_env_get_hsr()
- * \see long-lived-read
- *
- * \param [in] env             An environment handle returned
- *                             by \ref mdbx_env_create().
- * \param [in] hsr_callback    A \ref MDBX_hsr_func function
- *                             or NULL to disable.
- *
- * \returns A non-zero error value on failure and 0 on success. */
-LIBMDBX_API int mdbx_env_set_hsr(MDBX_env *env, MDBX_hsr_func *hsr_callback);
-
-/** \brief Gets current Handle-Slow-Readers callback used to resolve database
- * full/overflow issue due to a reader(s) which prevents the old data from being
- * recycled.
- * \see mdbx_env_set_hsr()
- *
- * \param [in] env   An environment handle returned by \ref mdbx_env_create().
- *
- * \returns A MDBX_hsr_func function or NULL if disabled
- *          or something wrong. */
-MDBX_NOTHROW_PURE_FUNCTION LIBMDBX_API MDBX_hsr_func *
-mdbx_env_get_hsr(const MDBX_env *env);
-
-/** \defgroup btree_traversal B-tree Traversal
- * This is internal API for mdbx_chk tool. You should avoid to use it, except
- * some extremal special cases.
- * \ingroup c_extra
- * @{ */
-
-/** \brief Page types for traverse the b-tree.
- * \see mdbx_env_pgwalk() \see MDBX_pgvisitor_func */
-enum MDBX_page_type_t {
-  MDBX_page_broken,
-  MDBX_page_meta,
-  MDBX_page_large,
-  MDBX_page_branch,
-  MDBX_page_leaf,
-  MDBX_page_dupfixed_leaf,
-  MDBX_subpage_leaf,
-  MDBX_subpage_dupfixed_leaf,
-  MDBX_subpage_broken,
-};
-#ifndef __cplusplus
-typedef enum MDBX_page_type_t MDBX_page_type_t;
-#endif
-
-/** \brief Pseudo-name for MainDB */
-#define MDBX_PGWALK_MAIN ((const char *)((ptrdiff_t)0))
-/** \brief Pseudo-name for GarbageCollectorDB */
-#define MDBX_PGWALK_GC ((const char *)((ptrdiff_t)-1))
-/** \brief Pseudo-name for MetaPages */
-#define MDBX_PGWALK_META ((const char *)((ptrdiff_t)-2))
-
-/** \brief Callback function for traverse the b-tree. \see mdbx_env_pgwalk() */
-typedef int MDBX_pgvisitor_func(
-    const uint64_t pgno, const unsigned number, void *const ctx, const int deep,
-    const char *const dbi, const size_t page_size, const MDBX_page_type_t type,
-    const MDBX_error_t err, const size_t nentries, const size_t payload_bytes,
-    const size_t header_bytes, const size_t unused_bytes) MDBX_CXX17_NOEXCEPT;
-
-/** \brief B-tree traversal function. */
-LIBMDBX_API int mdbx_env_pgwalk(MDBX_txn *txn, MDBX_pgvisitor_func *visitor,
-                                void *ctx, bool dont_check_keys_ordering);
-
-/** \brief Open an environment instance using specific meta-page
- * for checking and recovery.
- *
- * This function mostly of internal API for `mdbx_chk` utility and subject to
- * change at any time. Do not use this function to avoid shooting your own
- * leg(s). */
-LIBMDBX_API int mdbx_env_open_for_recovery(MDBX_env *env, const char *pathname,
-                                           unsigned target_meta,
-                                           bool writeable);
-
-/** \brief Turn database to the specified meta-page.
- *
- * This function mostly of internal API for `mdbx_chk` utility and subject to
- * change at any time. Do not use this function to avoid shooting your own
- * leg(s). */
-LIBMDBX_API int mdbx_env_turn_for_recovery(MDBX_env *env, unsigned target_meta);
-
-/** @} B-tree Traversal */
-
-/**** Attribute support functions for Nexenta
- * *******************************************/
-#if defined(MDBX_NEXENTA_ATTRS) || defined(DOXYGEN)
-/** \defgroup nexenta Attribute support functions for Nexenta
- * \ingroup c_crud
- * @{ */
-typedef uint_fast64_t mdbx_attr_t;
-
-/** Store by cursor with attribute.
- *
- * This function stores key/data pairs into the database. The cursor is
- * positioned at the new item, or on failure usually near it.
- *
- * \note Internally based on \ref MDBX_RESERVE feature,
- *       therefore doesn't support \ref MDBX_DUPSORT.
- *
- * \param [in] cursor  A cursor handle returned by \ref mdbx_cursor_open()
- * \param [in] key     The key operated on.
- * \param [in] data    The data operated on.
- * \param [in] attr    The attribute.
- * \param [in] flags   Options for this operation. This parameter must be set
- *                     to 0 or one of the values described here:
- *  - \ref MDBX_CURRENT
- *      Replace the item at the current cursor position. The key parameter
- *      must still be provided, and must match it, otherwise the function
- *      return \ref MDBX_EKEYMISMATCH.
- *
- *  - \ref MDBX_APPEND
- *      Append the given key/data pair to the end of the database. No key
- *      comparisons are performed. This option allows fast bulk loading when
- *      keys are already known to be in the correct order. Loading unsorted
- *      keys with this flag will cause a \ref MDBX_KEYEXIST error.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_EKEYMISMATCH
- * \retval MDBX_MAP_FULL  The database is full, see \ref mdbx_env_set_mapsize().
- * \retval MDBX_TXN_FULL  The transaction has too many dirty pages.
- * \retval MDBX_EACCES    An attempt was made to write in a read-only
- *                        transaction.
- * \retval MDBX_EINVAL    an invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_put_attr(MDBX_cursor *cursor, MDBX_val *key,
-                                     MDBX_val *data, mdbx_attr_t attr,
-                                     MDBX_put_flags_t flags);
-
-/** Store items and attributes into a database.
- *
- * This function stores key/data pairs in the database. The default behavior
- * is to enter the new key/data pair, replacing any previously existing key
- * if duplicates are disallowed.
- *
- * \note Internally based on \ref MDBX_RESERVE feature,
- *       therefore doesn't support \ref MDBX_DUPSORT.
- *
- * \param [in] txn       A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi       A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key       The key to store in the database.
- * \param [in] attr      The attribute to store in the database.
- * \param [in,out] data  The data to store.
- * \param [in] flags     Special options for this operation. This parameter
- *                       must be set to 0 or by bitwise OR'ing together one or
- *                       more of the values described here:
- *  - \ref MDBX_NOOVERWRITE
- *      Enter the new key/data pair only if the key does not already appear
- *      in the database. The function will return \ref MDBX_KEYEXIST if the key
- *      already appears in the database. The data parameter will be set to
- *      point to the existing item.
- *
- *  - \ref MDBX_CURRENT
- *      Update an single existing entry, but not add new ones. The function
- *      will return \ref MDBX_NOTFOUND if the given key not exist in the
- *      database. Or the \ref MDBX_EMULTIVAL in case duplicates for the given
- *     key.
- *
- *  - \ref MDBX_APPEND
- *      Append the given key/data pair to the end of the database. This option
- *      allows fast bulk loading when keys are already known to be in the
- *      correct order. Loading unsorted keys with this flag will cause
- *      a \ref MDBX_EKEYMISMATCH error.
- *
- * \see \ref c_crud_hints "Quick reference for Insert/Update/Delete operations"
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_KEYEXIST
- * \retval MDBX_MAP_FULL  The database is full, see \ref mdbx_env_set_mapsize().
- * \retval MDBX_TXN_FULL  The transaction has too many dirty pages.
- * \retval MDBX_EACCES    An attempt was made to write
- *                        in a read-only transaction.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_put_attr(MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key,
-                              MDBX_val *data, mdbx_attr_t attr,
-                              MDBX_put_flags_t flags);
-
-/** Set items attribute from a database.
- *
- * This function stores key/data pairs attribute to the database.
- *
- * \note Internally based on \ref MDBX_RESERVE feature,
- *       therefore doesn't support \ref MDBX_DUPSORT.
- *
- * \param [in] txn   A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi   A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key   The key to search for in the database.
- * \param [in] data  The data to be stored or NULL to save previous value.
- * \param [in] attr  The attribute to be stored.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_NOTFOUND   The key-value pair was not in the database.
- * \retval MDBX_EINVAL     An invalid parameter was specified. */
-LIBMDBX_API int mdbx_set_attr(MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key,
-                              MDBX_val *data, mdbx_attr_t attr);
-
-/** Get items attribute from a database cursor.
- *
- * This function retrieves key/data pairs from the database. The address and
- * length of the key are returned in the object to which key refers (except
- * for the case of the \ref MDBX_SET option, in which the key object is
- * unchanged), and the address and length of the data are returned in the object
- * to which data refers.
- * \see mdbx_get()
- *
- * \param [in] cursor    A cursor handle returned by \ref mdbx_cursor_open().
- * \param [in,out] key   The key for a retrieved item.
- * \param [in,out] data  The data of a retrieved item.
- * \param [out] pattr    The pointer to retrieve attribute.
- * \param [in] op        A cursor operation MDBX_cursor_op.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_NOTFOUND  No matching key found.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_cursor_get_attr(MDBX_cursor *cursor, MDBX_val *key,
-                                     MDBX_val *data, mdbx_attr_t *pattr,
-                                     MDBX_cursor_op op);
-
-/** Get items attribute from a database.
- *
- * This function retrieves key/data pairs from the database. The address
- * and length of the data associated with the specified key are returned
- * in the structure to which data refers.
- * If the database supports duplicate keys (see \ref MDBX_DUPSORT) then the
- * first data item for the key will be returned. Retrieval of other
- * items requires the use of \ref mdbx_cursor_get().
- *
- * \note The memory pointed to by the returned values is owned by the
- * database. The caller need not dispose of the memory, and may not
- * modify it in any way. For values returned in a read-only transaction
- * any modification attempts will cause a `SIGSEGV`.
- *
- * \note Values returned from the database are valid only until a
- * subsequent update operation, or the end of the transaction.
- *
- * \param [in] txn       A transaction handle returned by \ref mdbx_txn_begin().
- * \param [in] dbi       A database handle returned by \ref mdbx_dbi_open().
- * \param [in] key       The key to search for in the database.
- * \param [in,out] data  The data corresponding to the key.
- * \param [out] pattr    The pointer to retrieve attribute.
- *
- * \returns A non-zero error value on failure and 0 on success,
- *          some possible errors are:
- * \retval MDBX_NOTFOUND  The key was not in the database.
- * \retval MDBX_EINVAL    An invalid parameter was specified. */
-LIBMDBX_API int mdbx_get_attr(MDBX_txn *txn, MDBX_dbi dbi, MDBX_val *key,
-                              MDBX_val *data, mdbx_attr_t *pattr);
-/** @} end of Attribute support functions for Nexenta */
-#endif /* MDBX_NEXENTA_ATTRS */
-
-/** @} end of C API */
-
-/*******************************************************************************
- * Workaround for mmaped-lookahead-cross-page-boundary bug
- * in an obsolete versions of Elbrus's libc and kernels. */
-#if defined(__e2k__) && defined(MDBX_E2K_MLHCPB_WORKAROUND) &&                 \
-    MDBX_E2K_MLHCPB_WORKAROUND
-LIBMDBX_API int mdbx_e2k_memcmp_bug_workaround(const void *s1, const void *s2,
-                                               size_t n);
-LIBMDBX_API int mdbx_e2k_strcmp_bug_workaround(const char *s1, const char *s2);
-LIBMDBX_API int mdbx_e2k_strncmp_bug_workaround(const char *s1, const char *s2,
-                                                size_t n);
-LIBMDBX_API size_t mdbx_e2k_strlen_bug_workaround(const char *s);
-LIBMDBX_API size_t mdbx_e2k_strnlen_bug_workaround(const char *s,
-                                                   size_t maxlen);
-#ifdef __cplusplus
-namespace std {
-inline int mdbx_e2k_memcmp_bug_workaround(const void *s1, const void *s2,
-                                          size_t n) {
-  return ::mdbx_e2k_memcmp_bug_workaround(s1, s2, n);
-}
-inline int mdbx_e2k_strcmp_bug_workaround(const char *s1, const char *s2) {
-  return ::mdbx_e2k_strcmp_bug_workaround(s1, s2);
-}
-inline int mdbx_e2k_strncmp_bug_workaround(const char *s1, const char *s2,
-                                           size_t n) {
-  return ::mdbx_e2k_strncmp_bug_workaround(s1, s2, n);
-}
-inline size_t mdbx_e2k_strlen_bug_workaround(const char *s) {
-  return ::mdbx_e2k_strlen_bug_workaround(s);
-}
-inline size_t mdbx_e2k_strnlen_bug_workaround(const char *s, size_t maxlen) {
-  return ::mdbx_e2k_strnlen_bug_workaround(s, maxlen);
-}
-} // namespace std
-#endif /* __cplusplus */
-
-#include <string.h>
-#include <strings.h>
-#undef memcmp
-#define memcmp mdbx_e2k_memcmp_bug_workaround
-#undef bcmp
-#define bcmp mdbx_e2k_memcmp_bug_workaround
-#undef strcmp
-#define strcmp mdbx_e2k_strcmp_bug_workaround
-#undef strncmp
-#define strncmp mdbx_e2k_strncmp_bug_workaround
-#undef strlen
-#define strlen mdbx_e2k_strlen_bug_workaround
-#undef strnlen
-#define strnlen mdbx_e2k_strnlen_bug_workaround
-#endif /* MDBX_E2K_MLHCPB_WORKAROUND */
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-#endif /* LIBMDBX_H */