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Diffstat (limited to 'include/google/protobuf/arena.h')
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diff --git a/include/google/protobuf/arena.h b/include/google/protobuf/arena.h new file mode 100644 index 0000000000..3b5f16c389 --- /dev/null +++ b/include/google/protobuf/arena.h @@ -0,0 +1,851 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// This file defines an Arena allocator for better allocation performance. + +#ifndef GOOGLE_PROTOBUF_ARENA_H__ +#define GOOGLE_PROTOBUF_ARENA_H__ + + +#include <limits> +#include <type_traits> +#include <utility> +#if defined(_MSC_VER) && !defined(_LIBCPP_STD_VER) && !_HAS_EXCEPTIONS +// Work around bugs in MSVC <typeinfo> header when _HAS_EXCEPTIONS=0. +#include <exception> +#include <typeinfo> +namespace std { +using type_info = ::type_info; +} +#else +#include <typeinfo> +#endif + +#include <type_traits> +#include <google/protobuf/arena_impl.h> +#include <google/protobuf/port.h> + +// Must be included last. +#include <google/protobuf/port_def.inc> + +#ifdef SWIG +#error "You cannot SWIG proto headers" +#endif + +namespace google { +namespace protobuf { + +struct ArenaOptions; // defined below +class Arena; // defined below +class Message; // defined in message.h +class MessageLite; +template <typename Key, typename T> +class Map; + +namespace arena_metrics { + +void EnableArenaMetrics(ArenaOptions* options); + +} // namespace arena_metrics + +namespace TestUtil { +class ReflectionTester; // defined in test_util.h +} // namespace TestUtil + +namespace internal { + +struct ArenaTestPeer; // defined in arena_test_util.h +class InternalMetadata; // defined in metadata_lite.h +class LazyField; // defined in lazy_field.h +class EpsCopyInputStream; // defined in parse_context.h +class RepeatedPtrFieldBase; // defined in repeated_ptr_field.h + +template <typename Type> +class GenericTypeHandler; // defined in repeated_field.h + +inline PROTOBUF_ALWAYS_INLINE +void* AlignTo(void* ptr, size_t align) { + return reinterpret_cast<void*>( + (reinterpret_cast<uintptr_t>(ptr) + align - 1) & (~align + 1)); +} + +// Templated cleanup methods. +template <typename T> +void arena_destruct_object(void* object) { + reinterpret_cast<T*>(object)->~T(); +} + +template <bool destructor_skippable, typename T> +struct ObjectDestructor { + constexpr static void (*destructor)(void*) = &arena_destruct_object<T>; +}; + +template <typename T> +struct ObjectDestructor<true, T> { + constexpr static void (*destructor)(void*) = nullptr; +}; + +template <typename T> +void arena_delete_object(void* object) { + delete reinterpret_cast<T*>(object); +} +} // namespace internal + +// ArenaOptions provides optional additional parameters to arena construction +// that control its block-allocation behavior. +struct ArenaOptions { + // This defines the size of the first block requested from the system malloc. + // Subsequent block sizes will increase in a geometric series up to a maximum. + size_t start_block_size; + + // This defines the maximum block size requested from system malloc (unless an + // individual arena allocation request occurs with a size larger than this + // maximum). Requested block sizes increase up to this value, then remain + // here. + size_t max_block_size; + + // An initial block of memory for the arena to use, or NULL for none. If + // provided, the block must live at least as long as the arena itself. The + // creator of the Arena retains ownership of the block after the Arena is + // destroyed. + char* initial_block; + + // The size of the initial block, if provided. + size_t initial_block_size; + + // A function pointer to an alloc method that returns memory blocks of size + // requested. By default, it contains a ptr to the malloc function. + // + // NOTE: block_alloc and dealloc functions are expected to behave like + // malloc and free, including Asan poisoning. + void* (*block_alloc)(size_t); + // A function pointer to a dealloc method that takes ownership of the blocks + // from the arena. By default, it contains a ptr to a wrapper function that + // calls free. + void (*block_dealloc)(void*, size_t); + + ArenaOptions() + : start_block_size(internal::AllocationPolicy::kDefaultStartBlockSize), + max_block_size(internal::AllocationPolicy::kDefaultMaxBlockSize), + initial_block(NULL), + initial_block_size(0), + block_alloc(nullptr), + block_dealloc(nullptr), + make_metrics_collector(nullptr) {} + + private: + // If make_metrics_collector is not nullptr, it will be called at Arena init + // time. It may return a pointer to a collector instance that will be notified + // of interesting events related to the arena. + internal::ArenaMetricsCollector* (*make_metrics_collector)(); + + internal::ArenaMetricsCollector* MetricsCollector() const { + return make_metrics_collector ? (*make_metrics_collector)() : nullptr; + } + + internal::AllocationPolicy AllocationPolicy() const { + internal::AllocationPolicy res; + res.start_block_size = start_block_size; + res.max_block_size = max_block_size; + res.block_alloc = block_alloc; + res.block_dealloc = block_dealloc; + res.metrics_collector = MetricsCollector(); + return res; + } + + friend void arena_metrics::EnableArenaMetrics(ArenaOptions*); + + friend class Arena; + friend class ArenaOptionsTestFriend; +}; + +// Support for non-RTTI environments. (The metrics hooks API uses type +// information.) +#if PROTOBUF_RTTI +#define RTTI_TYPE_ID(type) (&typeid(type)) +#else +#define RTTI_TYPE_ID(type) (NULL) +#endif + +// Arena allocator. Arena allocation replaces ordinary (heap-based) allocation +// with new/delete, and improves performance by aggregating allocations into +// larger blocks and freeing allocations all at once. Protocol messages are +// allocated on an arena by using Arena::CreateMessage<T>(Arena*), below, and +// are automatically freed when the arena is destroyed. +// +// This is a thread-safe implementation: multiple threads may allocate from the +// arena concurrently. Destruction is not thread-safe and the destructing +// thread must synchronize with users of the arena first. +// +// An arena provides two allocation interfaces: CreateMessage<T>, which works +// for arena-enabled proto2 message types as well as other types that satisfy +// the appropriate protocol (described below), and Create<T>, which works for +// any arbitrary type T. CreateMessage<T> is better when the type T supports it, +// because this interface (i) passes the arena pointer to the created object so +// that its sub-objects and internal allocations can use the arena too, and (ii) +// elides the object's destructor call when possible. Create<T> does not place +// any special requirements on the type T, and will invoke the object's +// destructor when the arena is destroyed. +// +// The arena message allocation protocol, required by +// CreateMessage<T>(Arena* arena, Args&&... args), is as follows: +// +// - The type T must have (at least) two constructors: a constructor callable +// with `args` (without `arena`), called when a T is allocated on the heap; +// and a constructor callable with `Arena* arena, Args&&... args`, called when +// a T is allocated on an arena. If the second constructor is called with a +// NULL arena pointer, it must be equivalent to invoking the first +// (`args`-only) constructor. +// +// - The type T must have a particular type trait: a nested type +// |InternalArenaConstructable_|. This is usually a typedef to |void|. If no +// such type trait exists, then the instantiation CreateMessage<T> will fail +// to compile. +// +// - The type T *may* have the type trait |DestructorSkippable_|. If this type +// trait is present in the type, then its destructor will not be called if and +// only if it was passed a non-NULL arena pointer. If this type trait is not +// present on the type, then its destructor is always called when the +// containing arena is destroyed. +// +// This protocol is implemented by all arena-enabled proto2 message classes as +// well as protobuf container types like RepeatedPtrField and Map. The protocol +// is internal to protobuf and is not guaranteed to be stable. Non-proto types +// should not rely on this protocol. +class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final { + public: + // Default constructor with sensible default options, tuned for average + // use-cases. + inline Arena() : impl_() {} + + // Construct an arena with default options, except for the supplied + // initial block. It is more efficient to use this constructor + // instead of passing ArenaOptions if the only configuration needed + // by the caller is supplying an initial block. + inline Arena(char* initial_block, size_t initial_block_size) + : impl_(initial_block, initial_block_size) {} + + // Arena constructor taking custom options. See ArenaOptions above for + // descriptions of the options available. + explicit Arena(const ArenaOptions& options) + : impl_(options.initial_block, options.initial_block_size, + options.AllocationPolicy()) {} + + // Block overhead. Use this as a guide for how much to over-allocate the + // initial block if you want an allocation of size N to fit inside it. + // + // WARNING: if you allocate multiple objects, it is difficult to guarantee + // that a series of allocations will fit in the initial block, especially if + // Arena changes its alignment guarantees in the future! + static const size_t kBlockOverhead = + internal::ThreadSafeArena::kBlockHeaderSize + + internal::ThreadSafeArena::kSerialArenaSize; + + inline ~Arena() {} + + // TODO(protobuf-team): Fix callers to use constructor and delete this method. + void Init(const ArenaOptions&) {} + + // API to create proto2 message objects on the arena. If the arena passed in + // is NULL, then a heap allocated object is returned. Type T must be a message + // defined in a .proto file with cc_enable_arenas set to true, otherwise a + // compilation error will occur. + // + // RepeatedField and RepeatedPtrField may also be instantiated directly on an + // arena with this method. + // + // This function also accepts any type T that satisfies the arena message + // allocation protocol, documented above. + template <typename T, typename... Args> + PROTOBUF_ALWAYS_INLINE static T* CreateMessage(Arena* arena, Args&&... args) { + static_assert( + InternalHelper<T>::is_arena_constructable::value, + "CreateMessage can only construct types that are ArenaConstructable"); + // We must delegate to CreateMaybeMessage() and NOT CreateMessageInternal() + // because protobuf generated classes specialize CreateMaybeMessage() and we + // need to use that specialization for code size reasons. + return Arena::CreateMaybeMessage<T>(arena, static_cast<Args&&>(args)...); + } + + // API to create any objects on the arena. Note that only the object will + // be created on the arena; the underlying ptrs (in case of a proto2 message) + // will be still heap allocated. Proto messages should usually be allocated + // with CreateMessage<T>() instead. + // + // Note that even if T satisfies the arena message construction protocol + // (InternalArenaConstructable_ trait and optional DestructorSkippable_ + // trait), as described above, this function does not follow the protocol; + // instead, it treats T as a black-box type, just as if it did not have these + // traits. Specifically, T's constructor arguments will always be only those + // passed to Create<T>() -- no additional arena pointer is implicitly added. + // Furthermore, the destructor will always be called at arena destruction time + // (unless the destructor is trivial). Hence, from T's point of view, it is as + // if the object were allocated on the heap (except that the underlying memory + // is obtained from the arena). + template <typename T, typename... Args> + PROTOBUF_NDEBUG_INLINE static T* Create(Arena* arena, Args&&... args) { + return CreateInternal<T>(arena, std::is_convertible<T*, MessageLite*>(), + static_cast<Args&&>(args)...); + } + + // Allocates memory with the specific size and alignment. + void* AllocateAligned(size_t size, size_t align = 8) { + if (align <= 8) { + return AllocateAlignedNoHook(internal::AlignUpTo8(size)); + } else { + // We are wasting space by over allocating align - 8 bytes. Compared + // to a dedicated function that takes current alignment in consideration. + // Such a scheme would only waste (align - 8)/2 bytes on average, but + // requires a dedicated function in the outline arena allocation + // functions. Possibly re-evaluate tradeoffs later. + return internal::AlignTo(AllocateAlignedNoHook(size + align - 8), align); + } + } + + // Create an array of object type T on the arena *without* invoking the + // constructor of T. If `arena` is null, then the return value should be freed + // with `delete[] x;` (or `::operator delete[](x);`). + // To ensure safe uses, this function checks at compile time + // (when compiled as C++11) that T is trivially default-constructible and + // trivially destructible. + template <typename T> + PROTOBUF_NDEBUG_INLINE static T* CreateArray(Arena* arena, + size_t num_elements) { + static_assert(std::is_trivial<T>::value, + "CreateArray requires a trivially constructible type"); + static_assert(std::is_trivially_destructible<T>::value, + "CreateArray requires a trivially destructible type"); + GOOGLE_CHECK_LE(num_elements, std::numeric_limits<size_t>::max() / sizeof(T)) + << "Requested size is too large to fit into size_t."; + if (arena == NULL) { + return static_cast<T*>(::operator new[](num_elements * sizeof(T))); + } else { + return arena->CreateInternalRawArray<T>(num_elements); + } + } + + // The following are routines are for monitoring. They will approximate the + // total sum allocated and used memory, but the exact value is an + // implementation deal. For instance allocated space depends on growth + // policies. Do not use these in unit tests. + // Returns the total space allocated by the arena, which is the sum of the + // sizes of the underlying blocks. + uint64_t SpaceAllocated() const { return impl_.SpaceAllocated(); } + // Returns the total space used by the arena. Similar to SpaceAllocated but + // does not include free space and block overhead. The total space returned + // may not include space used by other threads executing concurrently with + // the call to this method. + uint64_t SpaceUsed() const { return impl_.SpaceUsed(); } + + // Frees all storage allocated by this arena after calling destructors + // registered with OwnDestructor() and freeing objects registered with Own(). + // Any objects allocated on this arena are unusable after this call. It also + // returns the total space used by the arena which is the sums of the sizes + // of the allocated blocks. This method is not thread-safe. + uint64_t Reset() { return impl_.Reset(); } + + // Adds |object| to a list of heap-allocated objects to be freed with |delete| + // when the arena is destroyed or reset. + template <typename T> + PROTOBUF_ALWAYS_INLINE void Own(T* object) { + OwnInternal(object, std::is_convertible<T*, MessageLite*>()); + } + + // Adds |object| to a list of objects whose destructors will be manually + // called when the arena is destroyed or reset. This differs from Own() in + // that it does not free the underlying memory with |delete|; hence, it is + // normally only used for objects that are placement-newed into + // arena-allocated memory. + template <typename T> + PROTOBUF_ALWAYS_INLINE void OwnDestructor(T* object) { + if (object != NULL) { + impl_.AddCleanup(object, &internal::arena_destruct_object<T>); + } + } + + // Adds a custom member function on an object to the list of destructors that + // will be manually called when the arena is destroyed or reset. This differs + // from OwnDestructor() in that any member function may be specified, not only + // the class destructor. + PROTOBUF_ALWAYS_INLINE void OwnCustomDestructor(void* object, + void (*destruct)(void*)) { + impl_.AddCleanup(object, destruct); + } + + // Retrieves the arena associated with |value| if |value| is an arena-capable + // message, or NULL otherwise. If possible, the call resolves at compile time. + // Note that we can often devirtualize calls to `value->GetArena()` so usually + // calling this method is unnecessary. + template <typename T> + PROTOBUF_ALWAYS_INLINE static Arena* GetArena(const T* value) { + return GetArenaInternal(value); + } + + template <typename T> + class InternalHelper { + private: + // Provides access to protected GetOwningArena to generated messages. + static Arena* GetOwningArena(const T* p) { return p->GetOwningArena(); } + + static void InternalSwap(T* a, T* b) { a->InternalSwap(b); } + + static Arena* GetArenaForAllocationInternal( + const T* p, std::true_type /*is_derived_from<MessageLite>*/) { + return p->GetArenaForAllocation(); + } + + static Arena* GetArenaForAllocationInternal( + const T* p, std::false_type /*is_derived_from<MessageLite>*/) { + return GetArenaForAllocationForNonMessage( + p, typename is_arena_constructable::type()); + } + + static Arena* GetArenaForAllocationForNonMessage( + const T* p, std::true_type /*is_arena_constructible*/) { + return p->GetArena(); + } + + static Arena* GetArenaForAllocationForNonMessage( + const T* p, std::false_type /*is_arena_constructible*/) { + return GetArenaForAllocationForNonMessageNonArenaConstructible( + p, typename has_get_arena::type()); + } + + static Arena* GetArenaForAllocationForNonMessageNonArenaConstructible( + const T* p, std::true_type /*has_get_arena*/) { + return p->GetArena(); + } + + static Arena* GetArenaForAllocationForNonMessageNonArenaConstructible( + const T* /* p */, std::false_type /*has_get_arena*/) { + return nullptr; + } + + template <typename U> + static char DestructorSkippable(const typename U::DestructorSkippable_*); + template <typename U> + static double DestructorSkippable(...); + + typedef std::integral_constant< + bool, sizeof(DestructorSkippable<T>(static_cast<const T*>(0))) == + sizeof(char) || + std::is_trivially_destructible<T>::value> + is_destructor_skippable; + + template <typename U> + static char ArenaConstructable( + const typename U::InternalArenaConstructable_*); + template <typename U> + static double ArenaConstructable(...); + + typedef std::integral_constant<bool, sizeof(ArenaConstructable<T>( + static_cast<const T*>(0))) == + sizeof(char)> + is_arena_constructable; + + template <typename U, + typename std::enable_if< + std::is_same<Arena*, decltype(std::declval<const U>() + .GetArena())>::value, + int>::type = 0> + static char HasGetArena(decltype(&U::GetArena)); + template <typename U> + static double HasGetArena(...); + + typedef std::integral_constant<bool, sizeof(HasGetArena<T>(nullptr)) == + sizeof(char)> + has_get_arena; + + template <typename... Args> + static T* Construct(void* ptr, Args&&... args) { + return new (ptr) T(static_cast<Args&&>(args)...); + } + + static inline PROTOBUF_ALWAYS_INLINE T* New() { + return new T(nullptr); + } + + static Arena* GetArena(const T* p) { return p->GetArena(); } + + friend class Arena; + friend class TestUtil::ReflectionTester; + }; + + // Provides access to protected GetOwningArena to generated messages. For + // internal use only. + template <typename T> + static Arena* InternalGetOwningArena(const T* p) { + return InternalHelper<T>::GetOwningArena(p); + } + + // Provides access to protected GetArenaForAllocation to generated messages. + // For internal use only. + template <typename T> + static Arena* InternalGetArenaForAllocation(const T* p) { + return InternalHelper<T>::GetArenaForAllocationInternal( + p, std::is_convertible<T*, MessageLite*>()); + } + + // Creates message-owned arena. For internal use only. + static Arena* InternalCreateMessageOwnedArena() { + return new Arena(internal::MessageOwned{}); + } + + // Checks whether this arena is message-owned. For internal use only. + bool InternalIsMessageOwnedArena() { return IsMessageOwned(); } + + // Helper typetraits that indicates support for arenas in a type T at compile + // time. This is public only to allow construction of higher-level templated + // utilities. + // + // is_arena_constructable<T>::value is true if the message type T has arena + // support enabled, and false otherwise. + // + // is_destructor_skippable<T>::value is true if the message type T has told + // the arena that it is safe to skip the destructor, and false otherwise. + // + // This is inside Arena because only Arena has the friend relationships + // necessary to see the underlying generated code traits. + template <typename T> + struct is_arena_constructable : InternalHelper<T>::is_arena_constructable {}; + template <typename T> + struct is_destructor_skippable : InternalHelper<T>::is_destructor_skippable { + }; + + private: + internal::ThreadSafeArena impl_; + + template <typename T> + struct has_get_arena : InternalHelper<T>::has_get_arena {}; + + // Constructor solely used by message-owned arena. + inline Arena(internal::MessageOwned) : impl_(internal::MessageOwned{}) {} + + // Checks whether this arena is message-owned. + PROTOBUF_ALWAYS_INLINE bool IsMessageOwned() const { + return impl_.IsMessageOwned(); + } + + void ReturnArrayMemory(void* p, size_t size) { + impl_.ReturnArrayMemory(p, size); + } + + template <typename T, typename... Args> + PROTOBUF_NDEBUG_INLINE static T* CreateMessageInternal(Arena* arena, + Args&&... args) { + static_assert( + InternalHelper<T>::is_arena_constructable::value, + "CreateMessage can only construct types that are ArenaConstructable"); + if (arena == NULL) { + return new T(nullptr, static_cast<Args&&>(args)...); + } else { + return arena->DoCreateMessage<T>(static_cast<Args&&>(args)...); + } + } + + // This specialization for no arguments is necessary, because its behavior is + // slightly different. When the arena pointer is nullptr, it calls T() + // instead of T(nullptr). + template <typename T> + PROTOBUF_NDEBUG_INLINE static T* CreateMessageInternal(Arena* arena) { + static_assert( + InternalHelper<T>::is_arena_constructable::value, + "CreateMessage can only construct types that are ArenaConstructable"); + if (arena == NULL) { + // Generated arena constructor T(Arena*) is protected. Call via + // InternalHelper. + return InternalHelper<T>::New(); + } else { + return arena->DoCreateMessage<T>(); + } + } + + // Allocate and also optionally call collector with the allocated type info + // when allocation recording is enabled. + PROTOBUF_NDEBUG_INLINE void* AllocateInternal(size_t size, size_t align, + void (*destructor)(void*), + const std::type_info* type) { + // Monitor allocation if needed. + if (destructor == nullptr) { + return AllocateAlignedWithHook(size, align, type); + } else { + if (align <= 8) { + auto res = AllocateAlignedWithCleanup(internal::AlignUpTo8(size), type); + res.second->elem = res.first; + res.second->cleanup = destructor; + return res.first; + } else { + auto res = AllocateAlignedWithCleanup(size + align - 8, type); + auto ptr = internal::AlignTo(res.first, align); + res.second->elem = ptr; + res.second->cleanup = destructor; + return ptr; + } + } + } + + // CreateMessage<T> requires that T supports arenas, but this private method + // works whether or not T supports arenas. These are not exposed to user code + // as it can cause confusing API usages, and end up having double free in + // user code. These are used only internally from LazyField and Repeated + // fields, since they are designed to work in all mode combinations. + template <typename Msg, typename... Args> + PROTOBUF_ALWAYS_INLINE static Msg* DoCreateMaybeMessage(Arena* arena, + std::true_type, + Args&&... args) { + return CreateMessageInternal<Msg>(arena, std::forward<Args>(args)...); + } + + template <typename T, typename... Args> + PROTOBUF_ALWAYS_INLINE static T* DoCreateMaybeMessage(Arena* arena, + std::false_type, + Args&&... args) { + return Create<T>(arena, std::forward<Args>(args)...); + } + + template <typename T, typename... Args> + PROTOBUF_ALWAYS_INLINE static T* CreateMaybeMessage(Arena* arena, + Args&&... args) { + return DoCreateMaybeMessage<T>(arena, is_arena_constructable<T>(), + std::forward<Args>(args)...); + } + + // Just allocate the required size for the given type assuming the + // type has a trivial constructor. + template <typename T> + PROTOBUF_NDEBUG_INLINE T* CreateInternalRawArray(size_t num_elements) { + GOOGLE_CHECK_LE(num_elements, std::numeric_limits<size_t>::max() / sizeof(T)) + << "Requested size is too large to fit into size_t."; + // We count on compiler to realize that if sizeof(T) is a multiple of + // 8 AlignUpTo can be elided. + const size_t n = sizeof(T) * num_elements; + return static_cast<T*>( + AllocateAlignedWithHookForArray(n, alignof(T), RTTI_TYPE_ID(T))); + } + + template <typename T, typename... Args> + PROTOBUF_NDEBUG_INLINE T* DoCreateMessage(Args&&... args) { + return InternalHelper<T>::Construct( + AllocateInternal(sizeof(T), alignof(T), + internal::ObjectDestructor< + InternalHelper<T>::is_destructor_skippable::value, + T>::destructor, + RTTI_TYPE_ID(T)), + this, std::forward<Args>(args)...); + } + + // CreateInArenaStorage is used to implement map field. Without it, + // Map need to call generated message's protected arena constructor, + // which needs to declare Map as friend of generated message. + template <typename T, typename... Args> + static void CreateInArenaStorage(T* ptr, Arena* arena, Args&&... args) { + CreateInArenaStorageInternal(ptr, arena, + typename is_arena_constructable<T>::type(), + std::forward<Args>(args)...); + if (arena != nullptr) { + RegisterDestructorInternal( + ptr, arena, + typename InternalHelper<T>::is_destructor_skippable::type()); + } + } + + template <typename T, typename... Args> + static void CreateInArenaStorageInternal(T* ptr, Arena* arena, + std::true_type, Args&&... args) { + InternalHelper<T>::Construct(ptr, arena, std::forward<Args>(args)...); + } + template <typename T, typename... Args> + static void CreateInArenaStorageInternal(T* ptr, Arena* /* arena */, + std::false_type, Args&&... args) { + new (ptr) T(std::forward<Args>(args)...); + } + + template <typename T> + static void RegisterDestructorInternal(T* /* ptr */, Arena* /* arena */, + std::true_type) {} + template <typename T> + static void RegisterDestructorInternal(T* ptr, Arena* arena, + std::false_type) { + arena->OwnDestructor(ptr); + } + + // These implement Create(). The second parameter has type 'true_type' if T is + // a subtype of Message and 'false_type' otherwise. + template <typename T, typename... Args> + PROTOBUF_ALWAYS_INLINE static T* CreateInternal(Arena* arena, std::true_type, + Args&&... args) { + if (arena == nullptr) { + return new T(std::forward<Args>(args)...); + } else { + auto destructor = + internal::ObjectDestructor<std::is_trivially_destructible<T>::value, + T>::destructor; + T* result = + new (arena->AllocateInternal(sizeof(T), alignof(T), destructor, + RTTI_TYPE_ID(T))) + T(std::forward<Args>(args)...); + return result; + } + } + template <typename T, typename... Args> + PROTOBUF_ALWAYS_INLINE static T* CreateInternal(Arena* arena, std::false_type, + Args&&... args) { + if (arena == nullptr) { + return new T(std::forward<Args>(args)...); + } else { + auto destructor = + internal::ObjectDestructor<std::is_trivially_destructible<T>::value, + T>::destructor; + return new (arena->AllocateInternal(sizeof(T), alignof(T), destructor, + RTTI_TYPE_ID(T))) + T(std::forward<Args>(args)...); + } + } + + // These implement Own(), which registers an object for deletion (destructor + // call and operator delete()). The second parameter has type 'true_type' if T + // is a subtype of Message and 'false_type' otherwise. Collapsing + // all template instantiations to one for generic Message reduces code size, + // using the virtual destructor instead. + template <typename T> + PROTOBUF_ALWAYS_INLINE void OwnInternal(T* object, std::true_type) { + if (object != NULL) { + impl_.AddCleanup(object, &internal::arena_delete_object<MessageLite>); + } + } + template <typename T> + PROTOBUF_ALWAYS_INLINE void OwnInternal(T* object, std::false_type) { + if (object != NULL) { + impl_.AddCleanup(object, &internal::arena_delete_object<T>); + } + } + + // Implementation for GetArena(). Only message objects with + // InternalArenaConstructable_ tags can be associated with an arena, and such + // objects must implement a GetArena() method. + template <typename T, typename std::enable_if< + is_arena_constructable<T>::value, int>::type = 0> + PROTOBUF_ALWAYS_INLINE static Arena* GetArenaInternal(const T* value) { + return InternalHelper<T>::GetArena(value); + } + template <typename T, + typename std::enable_if<!is_arena_constructable<T>::value && + has_get_arena<T>::value, + int>::type = 0> + PROTOBUF_ALWAYS_INLINE static Arena* GetArenaInternal(const T* value) { + return value->GetArena(); + } + template <typename T, + typename std::enable_if<!is_arena_constructable<T>::value && + !has_get_arena<T>::value, + int>::type = 0> + PROTOBUF_ALWAYS_INLINE static Arena* GetArenaInternal(const T* value) { + (void)value; + return nullptr; + } + + template <typename T> + PROTOBUF_ALWAYS_INLINE static Arena* GetOwningArena(const T* value) { + return GetOwningArenaInternal( + value, std::is_convertible<T*, MessageLite*>()); + } + + // Implementation for GetOwningArena(). All and only message objects have + // GetOwningArena() method. + template <typename T> + PROTOBUF_ALWAYS_INLINE static Arena* GetOwningArenaInternal( + const T* value, std::true_type) { + return InternalHelper<T>::GetOwningArena(value); + } + template <typename T> + PROTOBUF_ALWAYS_INLINE static Arena* GetOwningArenaInternal( + const T* /* value */, std::false_type) { + return nullptr; + } + + void* AllocateAlignedWithHookForArray(size_t n, size_t align, + const std::type_info* type) { + if (align <= 8) { + return AllocateAlignedWithHookForArray(internal::AlignUpTo8(n), type); + } else { + // We are wasting space by over allocating align - 8 bytes. Compared + // to a dedicated function that takes current alignment in consideration. + // Such a scheme would only waste (align - 8)/2 bytes on average, but + // requires a dedicated function in the outline arena allocation + // functions. Possibly re-evaluate tradeoffs later. + return internal::AlignTo( + AllocateAlignedWithHookForArray(n + align - 8, type), align); + } + } + + void* AllocateAlignedWithHook(size_t n, size_t align, + const std::type_info* type) { + if (align <= 8) { + return AllocateAlignedWithHook(internal::AlignUpTo8(n), type); + } else { + // We are wasting space by over allocating align - 8 bytes. Compared + // to a dedicated function that takes current alignment in consideration. + // Such a scheme would only waste (align - 8)/2 bytes on average, but + // requires a dedicated function in the outline arena allocation + // functions. Possibly re-evaluate tradeoffs later. + return internal::AlignTo(AllocateAlignedWithHook(n + align - 8, type), + align); + } + } + + void* AllocateAlignedNoHook(size_t n); + void* AllocateAlignedWithHook(size_t n, const std::type_info* type); + void* AllocateAlignedWithHookForArray(size_t n, const std::type_info* type); + std::pair<void*, internal::SerialArena::CleanupNode*> + AllocateAlignedWithCleanup(size_t n, const std::type_info* type); + + template <typename Type> + friend class internal::GenericTypeHandler; + friend class internal::InternalMetadata; // For user_arena(). + friend class internal::LazyField; // For CreateMaybeMessage. + friend class internal::EpsCopyInputStream; // For parser performance + friend class MessageLite; + template <typename Key, typename T> + friend class Map; + template <typename> + friend class RepeatedField; // For ReturnArrayMemory + friend class internal::RepeatedPtrFieldBase; // For ReturnArrayMemory + friend struct internal::ArenaTestPeer; +}; + +// Defined above for supporting environments without RTTI. +#undef RTTI_TYPE_ID + +} // namespace protobuf +} // namespace google + +#include <google/protobuf/port_undef.inc> + +#endif // GOOGLE_PROTOBUF_ARENA_H__ |