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diff --git a/libs/libevent/include/event2/event.h b/libs/libevent/include/event2/event.h new file mode 100644 index 0000000000..6e0a4f04c7 --- /dev/null +++ b/libs/libevent/include/event2/event.h @@ -0,0 +1,1675 @@ +/* + * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu> + * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. + */ +#ifndef EVENT2_EVENT_H_INCLUDED_ +#define EVENT2_EVENT_H_INCLUDED_ + +/** + @mainpage + + @section intro Introduction + + Libevent is an event notification library for developing scalable network + servers. The Libevent API provides a mechanism to execute a callback + function when a specific event occurs on a file descriptor or after a + timeout has been reached. Furthermore, Libevent also support callbacks due + to signals or regular timeouts. + + Libevent is meant to replace the event loop found in event driven network + servers. An application just needs to call event_base_dispatch() and then add or + remove events dynamically without having to change the event loop. + + + Currently, Libevent supports /dev/poll, kqueue(2), select(2), poll(2), + epoll(4), and evports. The internal event mechanism is completely + independent of the exposed event API, and a simple update of Libevent can + provide new functionality without having to redesign the applications. As a + result, Libevent allows for portable application development and provides + the most scalable event notification mechanism available on an operating + system. Libevent can also be used for multithreaded programs. Libevent + should compile on Linux, *BSD, Mac OS X, Solaris and, Windows. + + @section usage Standard usage + + Every program that uses Libevent must include the <event2/event.h> + header, and pass the -levent flag to the linker. (You can instead link + -levent_core if you only want the main event and buffered IO-based code, + and don't want to link any protocol code.) + + @section setup Library setup + + Before you call any other Libevent functions, you need to set up the + library. If you're going to use Libevent from multiple threads in a + multithreaded application, you need to initialize thread support -- + typically by using evthread_use_pthreads() or + evthread_use_windows_threads(). See <event2/thread.h> for more + information. + + This is also the point where you can replace Libevent's memory + management functions with event_set_mem_functions, and enable debug mode + with event_enable_debug_mode(). + + @section base Creating an event base + + Next, you need to create an event_base structure, using event_base_new() + or event_base_new_with_config(). The event_base is responsible for + keeping track of which events are "pending" (that is to say, being + watched to see if they become active) and which events are "active". + Every event is associated with a single event_base. + + @section event Event notification + + For each file descriptor that you wish to monitor, you must create an + event structure with event_new(). (You may also declare an event + structure and call event_assign() to initialize the members of the + structure.) To enable notification, you add the structure to the list + of monitored events by calling event_add(). The event structure must + remain allocated as long as it is active, so it should generally be + allocated on the heap. + + @section loop Dispatching events. + + Finally, you call event_base_dispatch() to loop and dispatch events. + You can also use event_base_loop() for more fine-grained control. + + Currently, only one thread can be dispatching a given event_base at a + time. If you want to run events in multiple threads at once, you can + either have a single event_base whose events add work to a work queue, + or you can create multiple event_base objects. + + @section bufferevent I/O Buffers + + Libevent provides a buffered I/O abstraction on top of the regular event + callbacks. This abstraction is called a bufferevent. A bufferevent + provides input and output buffers that get filled and drained + automatically. The user of a buffered event no longer deals directly + with the I/O, but instead is reading from input and writing to output + buffers. + + Once initialized via bufferevent_socket_new(), the bufferevent structure + can be used repeatedly with bufferevent_enable() and + bufferevent_disable(). Instead of reading and writing directly to a + socket, you would call bufferevent_read() and bufferevent_write(). + + When read enabled the bufferevent will try to read from the file descriptor + and call the read callback. The write callback is executed whenever the + output buffer is drained below the write low watermark, which is 0 by + default. + + See <event2/bufferevent*.h> for more information. + + @section timers Timers + + Libevent can also be used to create timers that invoke a callback after a + certain amount of time has expired. The evtimer_new() macro returns + an event struct to use as a timer. To activate the timer, call + evtimer_add(). Timers can be deactivated by calling evtimer_del(). + (These macros are thin wrappers around event_new(), event_add(), + and event_del(); you can also use those instead.) + + @section evdns Asynchronous DNS resolution + + Libevent provides an asynchronous DNS resolver that should be used instead + of the standard DNS resolver functions. See the <event2/dns.h> + functions for more detail. + + @section evhttp Event-driven HTTP servers + + Libevent provides a very simple event-driven HTTP server that can be + embedded in your program and used to service HTTP requests. + + To use this capability, you need to include the <event2/http.h> header in your + program. See that header for more information. + + @section evrpc A framework for RPC servers and clients + + Libevent provides a framework for creating RPC servers and clients. It + takes care of marshaling and unmarshaling all data structures. + + @section api API Reference + + To browse the complete documentation of the libevent API, click on any of + the following links. + + event2/event.h + The primary libevent header + + event2/thread.h + Functions for use by multithreaded programs + + event2/buffer.h and event2/bufferevent.h + Buffer management for network reading and writing + + event2/util.h + Utility functions for portable nonblocking network code + + event2/dns.h + Asynchronous DNS resolution + + event2/http.h + An embedded libevent-based HTTP server + + event2/rpc.h + A framework for creating RPC servers and clients + + */ + +/** @file event2/event.h + + Core functions for waiting for and receiving events, and using event bases. +*/ + +#include <event2/visibility.h> + +#ifdef __cplusplus +extern "C" { +#endif + +#include <event2/event-config.h> +#ifdef EVENT__HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#ifdef EVENT__HAVE_SYS_TIME_H +#include <sys/time.h> +#endif + +#include <stdio.h> + +/* For int types. */ +#include <event2/util.h> + +/** + * Structure to hold information and state for a Libevent dispatch loop. + * + * The event_base lies at the center of Libevent; every application will + * have one. It keeps track of all pending and active events, and + * notifies your application of the active ones. + * + * This is an opaque structure; you can allocate one using + * event_base_new() or event_base_new_with_config(). + * + * @see event_base_new(), event_base_free(), event_base_loop(), + * event_base_new_with_config() + */ +struct event_base +#ifdef EVENT_IN_DOXYGEN_ +{/*Empty body so that doxygen will generate documentation here.*/} +#endif +; + +/** + * @struct event + * + * Structure to represent a single event. + * + * An event can have some underlying condition it represents: a socket + * becoming readable or writeable (or both), or a signal becoming raised. + * (An event that represents no underlying condition is still useful: you + * can use one to implement a timer, or to communicate between threads.) + * + * Generally, you can create events with event_new(), then make them + * pending with event_add(). As your event_base runs, it will run the + * callbacks of an events whose conditions are triggered. When you + * longer want the event, free it with event_free(). + * + * In more depth: + * + * An event may be "pending" (one whose condition we are watching), + * "active" (one whose condition has triggered and whose callback is about + * to run), neither, or both. Events come into existence via + * event_assign() or event_new(), and are then neither active nor pending. + * + * To make an event pending, pass it to event_add(). When doing so, you + * can also set a timeout for the event. + * + * Events become active during an event_base_loop() call when either their + * condition has triggered, or when their timeout has elapsed. You can + * also activate an event manually using event_active(). The even_base + * loop will run the callbacks of active events; after it has done so, it + * marks them as no longer active. + * + * You can make an event non-pending by passing it to event_del(). This + * also makes the event non-active. + * + * Events can be "persistent" or "non-persistent". A non-persistent event + * becomes non-pending as soon as it is triggered: thus, it only runs at + * most once per call to event_add(). A persistent event remains pending + * even when it becomes active: you'll need to event_del() it manually in + * order to make it non-pending. When a persistent event with a timeout + * becomes active, its timeout is reset: this means you can use persistent + * events to implement periodic timeouts. + * + * This should be treated as an opaque structure; you should never read or + * write any of its fields directly. For backward compatibility with old + * code, it is defined in the event2/event_struct.h header; including this + * header may make your code incompatible with other versions of Libevent. + * + * @see event_new(), event_free(), event_assign(), event_get_assignment(), + * event_add(), event_del(), event_active(), event_pending(), + * event_get_fd(), event_get_base(), event_get_events(), + * event_get_callback(), event_get_callback_arg(), + * event_priority_set() + */ +struct event +#ifdef EVENT_IN_DOXYGEN_ +{/*Empty body so that doxygen will generate documentation here.*/} +#endif +; + +/** + * Configuration for an event_base. + * + * There are many options that can be used to alter the behavior and + * implementation of an event_base. To avoid having to pass them all in a + * complex many-argument constructor, we provide an abstract data type + * wrhere you set up configation information before passing it to + * event_base_new_with_config(). + * + * @see event_config_new(), event_config_free(), event_base_new_with_config(), + * event_config_avoid_method(), event_config_require_features(), + * event_config_set_flag(), event_config_set_num_cpus_hint() + */ +struct event_config +#ifdef EVENT_IN_DOXYGEN_ +{/*Empty body so that doxygen will generate documentation here.*/} +#endif +; + +/** + * Enable some relatively expensive debugging checks in Libevent that + * would normally be turned off. Generally, these checks cause code that + * would otherwise crash mysteriously to fail earlier with an assertion + * failure. Note that this method MUST be called before any events or + * event_bases have been created. + * + * Debug mode can currently catch the following errors: + * An event is re-assigned while it is added + * Any function is called on a non-assigned event + * + * Note that debugging mode uses memory to track every event that has been + * initialized (via event_assign, event_set, or event_new) but not yet + * released (via event_free or event_debug_unassign). If you want to use + * debug mode, and you find yourself running out of memory, you will need + * to use event_debug_unassign to explicitly stop tracking events that + * are no longer considered set-up. + * + * @see event_debug_unassign() + */ +EVENT2_EXPORT_SYMBOL +void event_enable_debug_mode(void); + +/** + * When debugging mode is enabled, informs Libevent that an event should no + * longer be considered as assigned. When debugging mode is not enabled, does + * nothing. + * + * This function must only be called on a non-added event. + * + * @see event_enable_debug_mode() + */ +EVENT2_EXPORT_SYMBOL +void event_debug_unassign(struct event *); + +/** + * Create and return a new event_base to use with the rest of Libevent. + * + * @return a new event_base on success, or NULL on failure. + * + * @see event_base_free(), event_base_new_with_config() + */ +EVENT2_EXPORT_SYMBOL +struct event_base *event_base_new(void); + +/** + Reinitialize the event base after a fork + + Some event mechanisms do not survive across fork. The event base needs + to be reinitialized with the event_reinit() function. + + @param base the event base that needs to be re-initialized + @return 0 if successful, or -1 if some events could not be re-added. + @see event_base_new() +*/ +EVENT2_EXPORT_SYMBOL +int event_reinit(struct event_base *base); + +/** + Event dispatching loop + + This loop will run the event base until either there are no more pending or + active, or until something calls event_base_loopbreak() or + event_base_loopexit(). + + @param base the event_base structure returned by event_base_new() or + event_base_new_with_config() + @return 0 if successful, -1 if an error occurred, or 1 if we exited because + no events were pending or active. + @see event_base_loop() + */ +EVENT2_EXPORT_SYMBOL +int event_base_dispatch(struct event_base *); + +/** + Get the kernel event notification mechanism used by Libevent. + + @param eb the event_base structure returned by event_base_new() + @return a string identifying the kernel event mechanism (kqueue, epoll, etc.) + */ +EVENT2_EXPORT_SYMBOL +const char *event_base_get_method(const struct event_base *); + +/** + Gets all event notification mechanisms supported by Libevent. + + This functions returns the event mechanism in order preferred by + Libevent. Note that this list will include all backends that + Libevent has compiled-in support for, and will not necessarily check + your OS to see whether it has the required resources. + + @return an array with pointers to the names of support methods. + The end of the array is indicated by a NULL pointer. If an + error is encountered NULL is returned. +*/ +EVENT2_EXPORT_SYMBOL +const char **event_get_supported_methods(void); + +/** Query the current monotonic time from a the timer for a struct + * event_base. + */ +EVENT2_EXPORT_SYMBOL +int event_gettime_monotonic(struct event_base *base, struct timeval *tp); + +/** + @name event type flag + + Flags to pass to event_base_get_num_events() to specify the kinds of events + we want to aggregate counts for +*/ +/**@{*/ +/** count the number of active events, which have been triggered.*/ +#define EVENT_BASE_COUNT_ACTIVE 1U +/** count the number of virtual events, which is used to represent an internal + * condition, other than a pending event, that keeps the loop from exiting. */ +#define EVENT_BASE_COUNT_VIRTUAL 2U +/** count the number of events which have been added to event base, including + * internal events. */ +#define EVENT_BASE_COUNT_ADDED 4U +/**@}*/ + +/** + Gets the number of events in event_base, as specified in the flags. + + Since event base has some internal events added to make some of its + functionalities work, EVENT_BASE_COUNT_ADDED may return more than the + number of events you added using event_add(). + + If you pass EVENT_BASE_COUNT_ACTIVE and EVENT_BASE_COUNT_ADDED together, an + active event will be counted twice. However, this might not be the case in + future libevent versions. The return value is an indication of the work + load, but the user shouldn't rely on the exact value as this may change in + the future. + + @param eb the event_base structure returned by event_base_new() + @param flags a bitwise combination of the kinds of events to aggregate + counts for + @return the number of events specified in the flags +*/ +EVENT2_EXPORT_SYMBOL +int event_base_get_num_events(struct event_base *, unsigned int); + +/** + Get the maximum number of events in a given event_base as specified in the + flags. + + @param eb the event_base structure returned by event_base_new() + @param flags a bitwise combination of the kinds of events to aggregate + counts for + @param clear option used to reset the maximum count. + @return the number of events specified in the flags + */ +EVENT2_EXPORT_SYMBOL +int event_base_get_max_events(struct event_base *, unsigned int, int); + +/** + Allocates a new event configuration object. + + The event configuration object can be used to change the behavior of + an event base. + + @return an event_config object that can be used to store configuration, or + NULL if an error is encountered. + @see event_base_new_with_config(), event_config_free(), event_config +*/ +EVENT2_EXPORT_SYMBOL +struct event_config *event_config_new(void); + +/** + Deallocates all memory associated with an event configuration object + + @param cfg the event configuration object to be freed. +*/ +EVENT2_EXPORT_SYMBOL +void event_config_free(struct event_config *cfg); + +/** + Enters an event method that should be avoided into the configuration. + + This can be used to avoid event mechanisms that do not support certain + file descriptor types, or for debugging to avoid certain event + mechanisms. An application can make use of multiple event bases to + accommodate incompatible file descriptor types. + + @param cfg the event configuration object + @param method the name of the event method to avoid + @return 0 on success, -1 on failure. +*/ +EVENT2_EXPORT_SYMBOL +int event_config_avoid_method(struct event_config *cfg, const char *method); + +/** + A flag used to describe which features an event_base (must) provide. + + Because of OS limitations, not every Libevent backend supports every + possible feature. You can use this type with + event_config_require_features() to tell Libevent to only proceed if your + event_base implements a given feature, and you can receive this type from + event_base_get_features() to see which features are available. +*/ +enum event_method_feature { + /** Require an event method that allows edge-triggered events with EV_ET. */ + EV_FEATURE_ET = 0x01, + /** Require an event method where having one event triggered among + * many is [approximately] an O(1) operation. This excludes (for + * example) select and poll, which are approximately O(N) for N + * equal to the total number of possible events. */ + EV_FEATURE_O1 = 0x02, + /** Require an event method that allows file descriptors as well as + * sockets. */ + EV_FEATURE_FDS = 0x04, + /** Require an event method that allows you to use EV_CLOSED to detect + * connection close without the necessity of reading all the pending data. + * + * Methods that do support EV_CLOSED may not be able to provide support on + * all kernel versions. + **/ + EV_FEATURE_EARLY_CLOSE = 0x08 +}; + +/** + A flag passed to event_config_set_flag(). + + These flags change the behavior of an allocated event_base. + + @see event_config_set_flag(), event_base_new_with_config(), + event_method_feature + */ +enum event_base_config_flag { + /** Do not allocate a lock for the event base, even if we have + locking set up. + + Setting this option will make it unsafe and nonfunctional to call + functions on the base concurrently from multiple threads. + */ + EVENT_BASE_FLAG_NOLOCK = 0x01, + /** Do not check the EVENT_* environment variables when configuring + an event_base */ + EVENT_BASE_FLAG_IGNORE_ENV = 0x02, + /** Windows only: enable the IOCP dispatcher at startup + + If this flag is set then bufferevent_socket_new() and + evconn_listener_new() will use IOCP-backed implementations + instead of the usual select-based one on Windows. + */ + EVENT_BASE_FLAG_STARTUP_IOCP = 0x04, + /** Instead of checking the current time every time the event loop is + ready to run timeout callbacks, check after each timeout callback. + */ + EVENT_BASE_FLAG_NO_CACHE_TIME = 0x08, + + /** If we are using the epoll backend, this flag says that it is + safe to use Libevent's internal change-list code to batch up + adds and deletes in order to try to do as few syscalls as + possible. Setting this flag can make your code run faster, but + it may trigger a Linux bug: it is not safe to use this flag + if you have any fds cloned by dup() or its variants. Doing so + will produce strange and hard-to-diagnose bugs. + + This flag can also be activated by setting the + EVENT_EPOLL_USE_CHANGELIST environment variable. + + This flag has no effect if you wind up using a backend other than + epoll. + */ + EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST = 0x10, + + /** Ordinarily, Libevent implements its time and timeout code using + the fastest monotonic timer that we have. If this flag is set, + however, we use less efficient more precise timer, assuming one is + present. + */ + EVENT_BASE_FLAG_PRECISE_TIMER = 0x20 +}; + +/** + Return a bitmask of the features implemented by an event base. This + will be a bitwise OR of one or more of the values of + event_method_feature + + @see event_method_feature + */ +EVENT2_EXPORT_SYMBOL +int event_base_get_features(const struct event_base *base); + +/** + Enters a required event method feature that the application demands. + + Note that not every feature or combination of features is supported + on every platform. Code that requests features should be prepared + to handle the case where event_base_new_with_config() returns NULL, as in: + <pre> + event_config_require_features(cfg, EV_FEATURE_ET); + base = event_base_new_with_config(cfg); + if (base == NULL) { + // We can't get edge-triggered behavior here. + event_config_require_features(cfg, 0); + base = event_base_new_with_config(cfg); + } + </pre> + + @param cfg the event configuration object + @param feature a bitfield of one or more event_method_feature values. + Replaces values from previous calls to this function. + @return 0 on success, -1 on failure. + @see event_method_feature, event_base_new_with_config() +*/ +EVENT2_EXPORT_SYMBOL +int event_config_require_features(struct event_config *cfg, int feature); + +/** + * Sets one or more flags to configure what parts of the eventual event_base + * will be initialized, and how they'll work. + * + * @see event_base_config_flags, event_base_new_with_config() + **/ +EVENT2_EXPORT_SYMBOL +int event_config_set_flag(struct event_config *cfg, int flag); + +/** + * Records a hint for the number of CPUs in the system. This is used for + * tuning thread pools, etc, for optimal performance. In Libevent 2.0, + * it is only on Windows, and only when IOCP is in use. + * + * @param cfg the event configuration object + * @param cpus the number of cpus + * @return 0 on success, -1 on failure. + */ +EVENT2_EXPORT_SYMBOL +int event_config_set_num_cpus_hint(struct event_config *cfg, int cpus); + +/** + * Record an interval and/or a number of callbacks after which the event base + * should check for new events. By default, the event base will run as many + * events are as activated at the higest activated priority before checking + * for new events. If you configure it by setting max_interval, it will check + * the time after each callback, and not allow more than max_interval to + * elapse before checking for new events. If you configure it by setting + * max_callbacks to a value >= 0, it will run no more than max_callbacks + * callbacks before checking for new events. + * + * This option can decrease the latency of high-priority events, and + * avoid priority inversions where multiple low-priority events keep us from + * polling for high-priority events, but at the expense of slightly decreasing + * the throughput. Use it with caution! + * + * @param cfg The event_base configuration object. + * @param max_interval An interval after which Libevent should stop running + * callbacks and check for more events, or NULL if there should be + * no such interval. + * @param max_callbacks A number of callbacks after which Libevent should + * stop running callbacks and check for more events, or -1 if there + * should be no such limit. + * @param min_priority A priority below which max_interval and max_callbacks + * should not be enforced. If this is set to 0, they are enforced + * for events of every priority; if it's set to 1, they're enforced + * for events of priority 1 and above, and so on. + * @return 0 on success, -1 on failure. + **/ +EVENT2_EXPORT_SYMBOL +int event_config_set_max_dispatch_interval(struct event_config *cfg, + const struct timeval *max_interval, int max_callbacks, + int min_priority); + +/** + Initialize the event API. + + Use event_base_new_with_config() to initialize a new event base, taking + the specified configuration under consideration. The configuration object + can currently be used to avoid certain event notification mechanisms. + + @param cfg the event configuration object + @return an initialized event_base that can be used to registering events, + or NULL if no event base can be created with the requested event_config. + @see event_base_new(), event_base_free(), event_init(), event_assign() +*/ +EVENT2_EXPORT_SYMBOL +struct event_base *event_base_new_with_config(const struct event_config *); + +/** + Deallocate all memory associated with an event_base, and free the base. + + Note that this function will not close any fds or free any memory passed + to event_new as the argument to callback. + + If there are any pending finalizer callbacks, this function will invoke + them. + + @param eb an event_base to be freed + */ +EVENT2_EXPORT_SYMBOL +void event_base_free(struct event_base *); + +/** + As event_free, but do not run finalizers. + + THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + BECOMES STABLE. + */ +EVENT2_EXPORT_SYMBOL +void event_base_free_nofinalize(struct event_base *); + +/** @name Log severities + */ +/**@{*/ +#define EVENT_LOG_DEBUG 0 +#define EVENT_LOG_MSG 1 +#define EVENT_LOG_WARN 2 +#define EVENT_LOG_ERR 3 +/**@}*/ + +/* Obsolete names: these are deprecated, but older programs might use them. + * They violate the reserved-identifier namespace. */ +#define _EVENT_LOG_DEBUG EVENT_LOG_DEBUG +#define _EVENT_LOG_MSG EVENT_LOG_MSG +#define _EVENT_LOG_WARN EVENT_LOG_WARN +#define _EVENT_LOG_ERR EVENT_LOG_ERR + +/** + A callback function used to intercept Libevent's log messages. + + @see event_set_log_callback + */ +typedef void (*event_log_cb)(int severity, const char *msg); +/** + Redirect Libevent's log messages. + + @param cb a function taking two arguments: an integer severity between + EVENT_LOG_DEBUG and EVENT_LOG_ERR, and a string. If cb is NULL, + then the default log is used. + + NOTE: The function you provide *must not* call any other libevent + functionality. Doing so can produce undefined behavior. + */ +EVENT2_EXPORT_SYMBOL +void event_set_log_callback(event_log_cb cb); + +/** + A function to be called if Libevent encounters a fatal internal error. + + @see event_set_fatal_callback + */ +typedef void (*event_fatal_cb)(int err); + +/** + Override Libevent's behavior in the event of a fatal internal error. + + By default, Libevent will call exit(1) if a programming error makes it + impossible to continue correct operation. This function allows you to supply + another callback instead. Note that if the function is ever invoked, + something is wrong with your program, or with Libevent: any subsequent calls + to Libevent may result in undefined behavior. + + Libevent will (almost) always log an EVENT_LOG_ERR message before calling + this function; look at the last log message to see why Libevent has died. + */ +EVENT2_EXPORT_SYMBOL +void event_set_fatal_callback(event_fatal_cb cb); + +#define EVENT_DBG_ALL 0xffffffffu +#define EVENT_DBG_NONE 0 + +/** + Turn on debugging logs and have them sent to the default log handler. + + This is a global setting; if you are going to call it, you must call this + before any calls that create an event-base. You must call it before any + multithreaded use of Libevent. + + Debug logs are verbose. + + @param which Controls which debug messages are turned on. This option is + unused for now; for forward compatibility, you must pass in the constant + "EVENT_DBG_ALL" to turn debugging logs on, or "EVENT_DBG_NONE" to turn + debugging logs off. + */ +EVENT2_EXPORT_SYMBOL +void event_enable_debug_logging(ev_uint32_t which); + +/** + Associate a different event base with an event. + + The event to be associated must not be currently active or pending. + + @param eb the event base + @param ev the event + @return 0 on success, -1 on failure. + */ +EVENT2_EXPORT_SYMBOL +int event_base_set(struct event_base *, struct event *); + +/** @name Loop flags + + These flags control the behavior of event_base_loop(). + */ +/**@{*/ +/** Block until we have an active event, then exit once all active events + * have had their callbacks run. */ +#define EVLOOP_ONCE 0x01 +/** Do not block: see which events are ready now, run the callbacks + * of the highest-priority ones, then exit. */ +#define EVLOOP_NONBLOCK 0x02 +/** Do not exit the loop because we have no pending events. Instead, keep + * running until event_base_loopexit() or event_base_loopbreak() makes us + * stop. + */ +#define EVLOOP_NO_EXIT_ON_EMPTY 0x04 +/**@}*/ + +/** + Wait for events to become active, and run their callbacks. + + This is a more flexible version of event_base_dispatch(). + + By default, this loop will run the event base until either there are no more + pending or active events, or until something calls event_base_loopbreak() or + event_base_loopexit(). You can override this behavior with the 'flags' + argument. + + @param eb the event_base structure returned by event_base_new() or + event_base_new_with_config() + @param flags any combination of EVLOOP_ONCE | EVLOOP_NONBLOCK + @return 0 if successful, -1 if an error occurred, or 1 if we exited because + no events were pending or active. + @see event_base_loopexit(), event_base_dispatch(), EVLOOP_ONCE, + EVLOOP_NONBLOCK + */ +EVENT2_EXPORT_SYMBOL +int event_base_loop(struct event_base *, int); + +/** + Exit the event loop after the specified time + + The next event_base_loop() iteration after the given timer expires will + complete normally (handling all queued events) then exit without + blocking for events again. + + Subsequent invocations of event_base_loop() will proceed normally. + + @param eb the event_base structure returned by event_init() + @param tv the amount of time after which the loop should terminate, + or NULL to exit after running all currently active events. + @return 0 if successful, or -1 if an error occurred + @see event_base_loopbreak() + */ +EVENT2_EXPORT_SYMBOL +int event_base_loopexit(struct event_base *, const struct timeval *); + +/** + Abort the active event_base_loop() immediately. + + event_base_loop() will abort the loop after the next event is completed; + event_base_loopbreak() is typically invoked from this event's callback. + This behavior is analogous to the "break;" statement. + + Subsequent invocations of event_base_loop() will proceed normally. + + @param eb the event_base structure returned by event_init() + @return 0 if successful, or -1 if an error occurred + @see event_base_loopexit() + */ +EVENT2_EXPORT_SYMBOL +int event_base_loopbreak(struct event_base *); + +/** + Tell the active event_base_loop() to scan for new events immediately. + + Calling this function makes the currently active event_base_loop() + start the loop over again (scanning for new events) after the current + event callback finishes. If the event loop is not running, this + function has no effect. + + event_base_loopbreak() is typically invoked from this event's callback. + This behavior is analogous to the "continue;" statement. + + Subsequent invocations of event loop will proceed normally. + + @param eb the event_base structure returned by event_init() + @return 0 if successful, or -1 if an error occurred + @see event_base_loopbreak() + */ +EVENT2_EXPORT_SYMBOL +int event_base_loopcontinue(struct event_base *); + +/** + Checks if the event loop was told to exit by event_base_loopexit(). + + This function will return true for an event_base at every point after + event_loopexit() is called, until the event loop is next entered. + + @param eb the event_base structure returned by event_init() + @return true if event_base_loopexit() was called on this event base, + or 0 otherwise + @see event_base_loopexit() + @see event_base_got_break() + */ +EVENT2_EXPORT_SYMBOL +int event_base_got_exit(struct event_base *); + +/** + Checks if the event loop was told to abort immediately by event_base_loopbreak(). + + This function will return true for an event_base at every point after + event_base_loopbreak() is called, until the event loop is next entered. + + @param eb the event_base structure returned by event_init() + @return true if event_base_loopbreak() was called on this event base, + or 0 otherwise + @see event_base_loopbreak() + @see event_base_got_exit() + */ +EVENT2_EXPORT_SYMBOL +int event_base_got_break(struct event_base *); + +/** + * @name event flags + * + * Flags to pass to event_new(), event_assign(), event_pending(), and + * anything else with an argument of the form "short events" + */ +/**@{*/ +/** Indicates that a timeout has occurred. It's not necessary to pass + * this flag to event_for new()/event_assign() to get a timeout. */ +#define EV_TIMEOUT 0x01 +/** Wait for a socket or FD to become readable */ +#define EV_READ 0x02 +/** Wait for a socket or FD to become writeable */ +#define EV_WRITE 0x04 +/** Wait for a POSIX signal to be raised*/ +#define EV_SIGNAL 0x08 +/** + * Persistent event: won't get removed automatically when activated. + * + * When a persistent event with a timeout becomes activated, its timeout + * is reset to 0. + */ +#define EV_PERSIST 0x10 +/** Select edge-triggered behavior, if supported by the backend. */ +#define EV_ET 0x20 +/** + * If this option is provided, then event_del() will not block in one thread + * while waiting for the event callback to complete in another thread. + * + * To use this option safely, you may need to use event_finalize() or + * event_free_finalize() in order to safely tear down an event in a + * multithreaded application. See those functions for more information. + * + * THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + * BECOMES STABLE. + **/ +#define EV_FINALIZE 0x40 +/** + * Detects connection close events. You can use this to detect when a + * connection has been closed, without having to read all the pending data + * from a connection. + * + * Not all backends support EV_CLOSED. To detect or require it, use the + * feature flag EV_FEATURE_EARLY_CLOSE. + **/ +#define EV_CLOSED 0x80 +/**@}*/ + +/** + @name evtimer_* macros + + Aliases for working with one-shot timer events */ +/**@{*/ +#define evtimer_assign(ev, b, cb, arg) \ + event_assign((ev), (b), -1, 0, (cb), (arg)) +#define evtimer_new(b, cb, arg) event_new((b), -1, 0, (cb), (arg)) +#define evtimer_add(ev, tv) event_add((ev), (tv)) +#define evtimer_del(ev) event_del(ev) +#define evtimer_pending(ev, tv) event_pending((ev), EV_TIMEOUT, (tv)) +#define evtimer_initialized(ev) event_initialized(ev) +/**@}*/ + +/** + @name evsignal_* macros + + Aliases for working with signal events + */ +/**@{*/ +#define evsignal_add(ev, tv) event_add((ev), (tv)) +#define evsignal_assign(ev, b, x, cb, arg) \ + event_assign((ev), (b), (x), EV_SIGNAL|EV_PERSIST, cb, (arg)) +#define evsignal_new(b, x, cb, arg) \ + event_new((b), (x), EV_SIGNAL|EV_PERSIST, (cb), (arg)) +#define evsignal_del(ev) event_del(ev) +#define evsignal_pending(ev, tv) event_pending((ev), EV_SIGNAL, (tv)) +#define evsignal_initialized(ev) event_initialized(ev) +/**@}*/ + +/** + A callback function for an event. + + It receives three arguments: + + @param fd An fd or signal + @param events One or more EV_* flags + @param arg A user-supplied argument. + + @see event_new() + */ +typedef void (*event_callback_fn)(evutil_socket_t, short, void *); + +/** + Return a value used to specify that the event itself must be used as the callback argument. + + The function event_new() takes a callback argument which is passed + to the event's callback function. To specify that the argument to be + passed to the callback function is the event that event_new() returns, + pass in the return value of event_self_cbarg() as the callback argument + for event_new(). + + For example: + <pre> + struct event *ev = event_new(base, sock, events, callback, %event_self_cbarg()); + </pre> + + For consistency with event_new(), it is possible to pass the return value + of this function as the callback argument for event_assign() – this + achieves the same result as passing the event in directly. + + @return a value to be passed as the callback argument to event_new() or + event_assign(). + @see event_new(), event_assign() + */ +EVENT2_EXPORT_SYMBOL +void *event_self_cbarg(void); + +/** + Allocate and asssign a new event structure, ready to be added. + + The function event_new() returns a new event that can be used in + future calls to event_add() and event_del(). The fd and events + arguments determine which conditions will trigger the event; the + callback and callback_arg arguments tell Libevent what to do when the + event becomes active. + + If events contains one of EV_READ, EV_WRITE, or EV_READ|EV_WRITE, then + fd is a file descriptor or socket that should get monitored for + readiness to read, readiness to write, or readiness for either operation + (respectively). If events contains EV_SIGNAL, then fd is a signal + number to wait for. If events contains none of those flags, then the + event can be triggered only by a timeout or by manual activation with + event_active(): In this case, fd must be -1. + + The EV_PERSIST flag can also be passed in the events argument: it makes + event_add() persistent until event_del() is called. + + The EV_ET flag is compatible with EV_READ and EV_WRITE, and supported + only by certain backends. It tells Libevent to use edge-triggered + events. + + The EV_TIMEOUT flag has no effect here. + + It is okay to have multiple events all listening on the same fds; but + they must either all be edge-triggered, or all not be edge triggerd. + + When the event becomes active, the event loop will run the provided + callbuck function, with three arguments. The first will be the provided + fd value. The second will be a bitfield of the events that triggered: + EV_READ, EV_WRITE, or EV_SIGNAL. Here the EV_TIMEOUT flag indicates + that a timeout occurred, and EV_ET indicates that an edge-triggered + event occurred. The third event will be the callback_arg pointer that + you provide. + + @param base the event base to which the event should be attached. + @param fd the file descriptor or signal to be monitored, or -1. + @param events desired events to monitor: bitfield of EV_READ, EV_WRITE, + EV_SIGNAL, EV_PERSIST, EV_ET. + @param callback callback function to be invoked when the event occurs + @param callback_arg an argument to be passed to the callback function + + @return a newly allocated struct event that must later be freed with + event_free(). + @see event_free(), event_add(), event_del(), event_assign() + */ +EVENT2_EXPORT_SYMBOL +struct event *event_new(struct event_base *, evutil_socket_t, short, event_callback_fn, void *); + + +/** + Prepare a new, already-allocated event structure to be added. + + The function event_assign() prepares the event structure ev to be used + in future calls to event_add() and event_del(). Unlike event_new(), it + doesn't allocate memory itself: it requires that you have already + allocated a struct event, probably on the heap. Doing this will + typically make your code depend on the size of the event structure, and + thereby create incompatibility with future versions of Libevent. + + The easiest way to avoid this problem is just to use event_new() and + event_free() instead. + + A slightly harder way to future-proof your code is to use + event_get_struct_event_size() to determine the required size of an event + at runtime. + + Note that it is NOT safe to call this function on an event that is + active or pending. Doing so WILL corrupt internal data structures in + Libevent, and lead to strange, hard-to-diagnose bugs. You _can_ use + event_assign to change an existing event, but only if it is not active + or pending! + + The arguments for this function, and the behavior of the events that it + makes, are as for event_new(). + + @param ev an event struct to be modified + @param base the event base to which ev should be attached. + @param fd the file descriptor to be monitored + @param events desired events to monitor; can be EV_READ and/or EV_WRITE + @param callback callback function to be invoked when the event occurs + @param callback_arg an argument to be passed to the callback function + + @return 0 if success, or -1 on invalid arguments. + + @see event_new(), event_add(), event_del(), event_base_once(), + event_get_struct_event_size() + */ +EVENT2_EXPORT_SYMBOL +int event_assign(struct event *, struct event_base *, evutil_socket_t, short, event_callback_fn, void *); + +/** + Deallocate a struct event * returned by event_new(). + + If the event is pending or active, first make it non-pending and + non-active. + */ +EVENT2_EXPORT_SYMBOL +void event_free(struct event *); + +/** + * Callback type for event_finalize and event_free_finalize(). + * + * THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + * BECOMES STABLE. + * + **/ +typedef void (*event_finalize_callback_fn)(struct event *, void *); +/** + @name Finalization functions + + These functions are used to safely tear down an event in a multithreaded + application. If you construct your events with EV_FINALIZE to avoid + deadlocks, you will need a way to remove an event in the certainty that + it will definitely not be running its callback when you deallocate it + and its callback argument. + + To do this, call one of event_finalize() or event_free_finalize with + 0 for its first argument, the event to tear down as its second argument, + and a callback function as its third argument. The callback will be + invoked as part of the event loop, with the event's priority. + + After you call a finalizer function, event_add() and event_active() will + no longer work on the event, and event_del() will produce a no-op. You + must not try to change the event's fields with event_assign() or + event_set() while the finalize callback is in progress. Once the + callback has been invoked, you should treat the event structure as + containing uninitialized memory. + + The event_free_finalize() function frees the event after it's finalized; + event_finalize() does not. + + A finalizer callback must not make events pending or active. It must not + add events, activate events, or attempt to "resucitate" the event being + finalized in any way. + + THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + BECOMES STABLE. + + @return 0 on succes, -1 on failure. + */ +/**@{*/ +EVENT2_EXPORT_SYMBOL +int event_finalize(unsigned, struct event *, event_finalize_callback_fn); +EVENT2_EXPORT_SYMBOL +int event_free_finalize(unsigned, struct event *, event_finalize_callback_fn); +/**@}*/ + +/** + Schedule a one-time event + + The function event_base_once() is similar to event_new(). However, it + schedules a callback to be called exactly once, and does not require the + caller to prepare an event structure. + + Note that in Libevent 2.0 and earlier, if the event is never triggered, the + internal memory used to hold it will never be freed. In Libevent 2.1, + the internal memory will get freed by event_base_free() if the event + is never triggered. The 'arg' value, however, will not get freed in either + case--you'll need to free that on your own if you want it to go away. + + @param base an event_base + @param fd a file descriptor to monitor, or -1 for no fd. + @param events event(s) to monitor; can be any of EV_READ | + EV_WRITE, or EV_TIMEOUT + @param callback callback function to be invoked when the event occurs + @param arg an argument to be passed to the callback function + @param timeout the maximum amount of time to wait for the event. NULL + makes an EV_READ/EV_WRITE event make forever; NULL makes an + EV_TIMEOUT event succees immediately. + @return 0 if successful, or -1 if an error occurred + */ +EVENT2_EXPORT_SYMBOL +int event_base_once(struct event_base *, evutil_socket_t, short, event_callback_fn, void *, const struct timeval *); + +/** + Add an event to the set of pending events. + + The function event_add() schedules the execution of the event 'ev' when the + condition specified by event_assign() or event_new() occurs, or when the time + specified in timeout has elapesed. If atimeout is NULL, no timeout + occurs and the function will only be + called if a matching event occurs. The event in the + ev argument must be already initialized by event_assign() or event_new() + and may not be used + in calls to event_assign() until it is no longer pending. + + If the event in the ev argument already has a scheduled timeout, calling + event_add() replaces the old timeout with the new one if tv is non-NULL. + + @param ev an event struct initialized via event_assign() or event_new() + @param timeout the maximum amount of time to wait for the event, or NULL + to wait forever + @return 0 if successful, or -1 if an error occurred + @see event_del(), event_assign(), event_new() + */ +EVENT2_EXPORT_SYMBOL +int event_add(struct event *ev, const struct timeval *timeout); + +/** + Remove a timer from a pending event without removing the event itself. + + If the event has a scheduled timeout, this function unschedules it but + leaves the event otherwise pending. + + @param ev an event struct initialized via event_assign() or event_new() + @return 0 on success, or -1 if an error occurrect. +*/ +EVENT2_EXPORT_SYMBOL +int event_remove_timer(struct event *ev); + +/** + Remove an event from the set of monitored events. + + The function event_del() will cancel the event in the argument ev. If the + event has already executed or has never been added the call will have no + effect. + + @param ev an event struct to be removed from the working set + @return 0 if successful, or -1 if an error occurred + @see event_add() + */ +EVENT2_EXPORT_SYMBOL +int event_del(struct event *); + +/** + As event_del(), but never blocks while the event's callback is running + in another thread, even if the event was constructed without the + EV_FINALIZE flag. + + THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + BECOMES STABLE. + */ +EVENT2_EXPORT_SYMBOL +int event_del_noblock(struct event *ev); +/** + As event_del(), but always blocks while the event's callback is running + in another thread, even if the event was constructed with the + EV_FINALIZE flag. + + THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES + BECOMES STABLE. + */ +EVENT2_EXPORT_SYMBOL +int event_del_block(struct event *ev); + +/** + Make an event active. + + You can use this function on a pending or a non-pending event to make it + active, so that its callback will be run by event_base_dispatch() or + event_base_loop(). + + One common use in multithreaded programs is to wake the thread running + event_base_loop() from another thread. + + @param ev an event to make active. + @param res a set of flags to pass to the event's callback. + @param ncalls an obsolete argument: this is ignored. + **/ +EVENT2_EXPORT_SYMBOL +void event_active(struct event *ev, int res, short ncalls); + +/** + Checks if a specific event is pending or scheduled. + + @param ev an event struct previously passed to event_add() + @param events the requested event type; any of EV_TIMEOUT|EV_READ| + EV_WRITE|EV_SIGNAL + @param tv if this field is not NULL, and the event has a timeout, + this field is set to hold the time at which the timeout will + expire. + + @return true if the event is pending on any of the events in 'what', (that + is to say, it has been added), or 0 if the event is not added. + */ +EVENT2_EXPORT_SYMBOL +int event_pending(const struct event *ev, short events, struct timeval *tv); + +/** + If called from within the callback for an event, returns that event. + + The behavior of this function is not defined when called from outside the + callback function for an event. + */ +EVENT2_EXPORT_SYMBOL +struct event *event_base_get_running_event(struct event_base *base); + +/** + Test if an event structure might be initialized. + + The event_initialized() function can be used to check if an event has been + initialized. + + Warning: This function is only useful for distinguishing a a zeroed-out + piece of memory from an initialized event, it can easily be confused by + uninitialized memory. Thus, it should ONLY be used to distinguish an + initialized event from zero. + + @param ev an event structure to be tested + @return 1 if the structure might be initialized, or 0 if it has not been + initialized + */ +EVENT2_EXPORT_SYMBOL +int event_initialized(const struct event *ev); + +/** + Get the signal number assigned to a signal event +*/ +#define event_get_signal(ev) ((int)event_get_fd(ev)) + +/** + Get the socket or signal assigned to an event, or -1 if the event has + no socket. +*/ +EVENT2_EXPORT_SYMBOL +evutil_socket_t event_get_fd(const struct event *ev); + +/** + Get the event_base associated with an event. +*/ +EVENT2_EXPORT_SYMBOL +struct event_base *event_get_base(const struct event *ev); + +/** + Return the events (EV_READ, EV_WRITE, etc) assigned to an event. +*/ +EVENT2_EXPORT_SYMBOL +short event_get_events(const struct event *ev); + +/** + Return the callback assigned to an event. +*/ +EVENT2_EXPORT_SYMBOL +event_callback_fn event_get_callback(const struct event *ev); + +/** + Return the callback argument assigned to an event. +*/ +EVENT2_EXPORT_SYMBOL +void *event_get_callback_arg(const struct event *ev); + +/** + Return the priority of an event. + @see event_priority_init(), event_get_priority() +*/ +EVENT2_EXPORT_SYMBOL +int event_get_priority(const struct event *ev); + +/** + Extract _all_ of arguments given to construct a given event. The + event_base is copied into *base_out, the fd is copied into *fd_out, and so + on. + + If any of the "_out" arguments is NULL, it will be ignored. + */ +EVENT2_EXPORT_SYMBOL +void event_get_assignment(const struct event *event, + struct event_base **base_out, evutil_socket_t *fd_out, short *events_out, + event_callback_fn *callback_out, void **arg_out); + +/** + Return the size of struct event that the Libevent library was compiled + with. + + This will be NO GREATER than sizeof(struct event) if you're running with + the same version of Libevent that your application was built with, but + otherwise might not. + + Note that it might be SMALLER than sizeof(struct event) if some future + version of Libevent adds extra padding to the end of struct event. + We might do this to help ensure ABI-compatibility between different + versions of Libevent. + */ +EVENT2_EXPORT_SYMBOL +size_t event_get_struct_event_size(void); + +/** + Get the Libevent version. + + Note that this will give you the version of the library that you're + currently linked against, not the version of the headers that you've + compiled against. + + @return a string containing the version number of Libevent +*/ +EVENT2_EXPORT_SYMBOL +const char *event_get_version(void); + +/** + Return a numeric representation of Libevent's version. + + Note that this will give you the version of the library that you're + currently linked against, not the version of the headers you've used to + compile. + + The format uses one byte each for the major, minor, and patchlevel parts of + the version number. The low-order byte is unused. For example, version + 2.0.1-alpha has a numeric representation of 0x02000100 +*/ +EVENT2_EXPORT_SYMBOL +ev_uint32_t event_get_version_number(void); + +/** As event_get_version, but gives the version of Libevent's headers. */ +#define LIBEVENT_VERSION EVENT__VERSION +/** As event_get_version_number, but gives the version number of Libevent's + * headers. */ +#define LIBEVENT_VERSION_NUMBER EVENT__NUMERIC_VERSION + +/** Largest number of priorities that Libevent can support. */ +#define EVENT_MAX_PRIORITIES 256 +/** + Set the number of different event priorities + + By default Libevent schedules all active events with the same priority. + However, some time it is desirable to process some events with a higher + priority than others. For that reason, Libevent supports strict priority + queues. Active events with a lower priority are always processed before + events with a higher priority. + + The number of different priorities can be set initially with the + event_base_priority_init() function. This function should be called + before the first call to event_base_dispatch(). The + event_priority_set() function can be used to assign a priority to an + event. By default, Libevent assigns the middle priority to all events + unless their priority is explicitly set. + + Note that urgent-priority events can starve less-urgent events: after + running all urgent-priority callbacks, Libevent checks for more urgent + events again, before running less-urgent events. Less-urgent events + will not have their callbacks run until there are no events more urgent + than them that want to be active. + + @param eb the event_base structure returned by event_base_new() + @param npriorities the maximum number of priorities + @return 0 if successful, or -1 if an error occurred + @see event_priority_set() + */ +EVENT2_EXPORT_SYMBOL +int event_base_priority_init(struct event_base *, int); + +/** + Get the number of different event priorities. + + @param eb the event_base structure returned by event_base_new() + @return Number of different event priorities + @see event_base_priority_init() +*/ +EVENT2_EXPORT_SYMBOL +int event_base_get_npriorities(struct event_base *eb); + +/** + Assign a priority to an event. + + @param ev an event struct + @param priority the new priority to be assigned + @return 0 if successful, or -1 if an error occurred + @see event_priority_init(), event_get_priority() + */ +EVENT2_EXPORT_SYMBOL +int event_priority_set(struct event *, int); + +/** + Prepare an event_base to use a large number of timeouts with the same + duration. + + Libevent's default scheduling algorithm is optimized for having a large + number of timeouts with their durations more or less randomly + distributed. But if you have a large number of timeouts that all have + the same duration (for example, if you have a large number of + connections that all have a 10-second timeout), then you can improve + Libevent's performance by telling Libevent about it. + + To do this, call this function with the common duration. It will return a + pointer to a different, opaque timeout value. (Don't depend on its actual + contents!) When you use this timeout value in event_add(), Libevent will + schedule the event more efficiently. + + (This optimization probably will not be worthwhile until you have thousands + or tens of thousands of events with the same timeout.) + */ +EVENT2_EXPORT_SYMBOL +const struct timeval *event_base_init_common_timeout(struct event_base *base, + const struct timeval *duration); + +#if !defined(EVENT__DISABLE_MM_REPLACEMENT) || defined(EVENT_IN_DOXYGEN_) +/** + Override the functions that Libevent uses for memory management. + + Usually, Libevent uses the standard libc functions malloc, realloc, and + free to allocate memory. Passing replacements for those functions to + event_set_mem_functions() overrides this behavior. + + Note that all memory returned from Libevent will be allocated by the + replacement functions rather than by malloc() and realloc(). Thus, if you + have replaced those functions, it will not be appropriate to free() memory + that you get from Libevent. Instead, you must use the free_fn replacement + that you provided. + + Note also that if you are going to call this function, you should do so + before any call to any Libevent function that does allocation. + Otherwise, those funtions will allocate their memory using malloc(), but + then later free it using your provided free_fn. + + @param malloc_fn A replacement for malloc. + @param realloc_fn A replacement for realloc + @param free_fn A replacement for free. + **/ +EVENT2_EXPORT_SYMBOL +void event_set_mem_functions( + void *(*malloc_fn)(size_t sz), + void *(*realloc_fn)(void *ptr, size_t sz), + void (*free_fn)(void *ptr)); +/** This definition is present if Libevent was built with support for + event_set_mem_functions() */ +#define EVENT_SET_MEM_FUNCTIONS_IMPLEMENTED +#endif + +/** + Writes a human-readable description of all inserted and/or active + events to a provided stdio stream. + + This is intended for debugging; its format is not guaranteed to be the same + between libevent versions. + + @param base An event_base on which to scan the events. + @param output A stdio file to write on. + */ +EVENT2_EXPORT_SYMBOL +void event_base_dump_events(struct event_base *, FILE *); + + +/** + Activates all pending events for the given fd and event mask. + + This function activates pending events only. Events which have not been + added will not become active. + + @param base the event_base on which to activate the events. + @param fd An fd to active events on. + @param events One or more of EV_{READ,WRITE}. + */ +EVENT2_EXPORT_SYMBOL +void event_base_active_by_fd(struct event_base *base, evutil_socket_t fd, short events); + +/** + Activates all pending signals with a given signal number + + This function activates pending events only. Events which have not been + added will not become active. + + @param base the event_base on which to activate the events. + @param fd The signal to active events on. + */ +EVENT2_EXPORT_SYMBOL +void event_base_active_by_signal(struct event_base *base, int sig); + +/** + * Callback for iterating events in an event base via event_base_foreach_event + */ +typedef int (*event_base_foreach_event_cb)(const struct event_base *, const struct event *, void *); + +/** + Iterate over all added or active events events in an event loop, and invoke + a given callback on each one. + + The callback must not call any function that modifies the event base, that + modifies any event in the event base, or that adds or removes any event to + the event base. Doing so is unsupported and will lead to undefined + behavior -- likely, to crashes. + + event_base_foreach_event() holds a lock on the event_base() for the whole + time it's running: slow callbacks are not advisable. + + Note that Libevent adds some events of its own to make pieces of its + functionality work. You must not assume that the only events you'll + encounter will be the ones you added yourself. + + The callback function must return 0 to continue iteration, or some other + integer to stop iterating. + + @param base An event_base on which to scan the events. + @param fn A callback function to receive the events. + @param arg An argument passed to the callback function. + @return 0 if we iterated over every event, or the value returned by the + callback function if the loop exited early. +*/ +EVENT2_EXPORT_SYMBOL +int event_base_foreach_event(struct event_base *base, event_base_foreach_event_cb fn, void *arg); + + +/** Sets 'tv' to the current time (as returned by gettimeofday()), + looking at the cached value in 'base' if possible, and calling + gettimeofday() or clock_gettime() as appropriate if there is no + cached time. + + Generally, this value will only be cached while actually + processing event callbacks, and may be very inaccuate if your + callbacks take a long time to execute. + + Returns 0 on success, negative on failure. + */ +EVENT2_EXPORT_SYMBOL +int event_base_gettimeofday_cached(struct event_base *base, + struct timeval *tv); + +/** Update cached_tv in the 'base' to the current time + * + * You can use this function is useful for selectively increasing + * the accuracy of the cached time value in 'base' during callbacks + * that take a long time to execute. + * + * This function has no effect if the base is currently not in its + * event loop, or if timeval caching is disabled via + * EVENT_BASE_FLAG_NO_CACHE_TIME. + * + * @return 0 on success, -1 on failure + */ +EVENT2_EXPORT_SYMBOL +int event_base_update_cache_time(struct event_base *base); + +/** Release up all globally-allocated resources allocated by Libevent. + + This function does not free developer-controlled resources like + event_bases, events, bufferevents, listeners, and so on. It only releases + resources like global locks that there is no other way to free. + + It is not actually necessary to call this function before exit: every + resource that it frees would be released anyway on exit. It mainly exists + so that resource-leak debugging tools don't see Libevent as holding + resources at exit. + + You should only call this function when no other Libevent functions will + be invoked -- e.g., when cleanly exiting a program. + */ +EVENT2_EXPORT_SYMBOL +void libevent_global_shutdown(void); + +#ifdef __cplusplus +} +#endif + +#endif /* EVENT2_EVENT_H_INCLUDED_ */ |