1/*
2 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27#ifndef EVENT2_EVENT_H_INCLUDED_
28#define EVENT2_EVENT_H_INCLUDED_
29
30/**
31 @mainpage
32
33 @section intro Introduction
34
35 Libevent is an event notification library for developing scalable network
36 servers. The Libevent API provides a mechanism to execute a callback
37 function when a specific event occurs on a file descriptor or after a
38 timeout has been reached. Furthermore, Libevent also support callbacks due
39 to signals or regular timeouts.
40
41 Libevent is meant to replace the event loop found in event driven network
42 servers. An application just needs to call event_base_dispatch() and then add or
43 remove events dynamically without having to change the event loop.
44
45
46 Currently, Libevent supports /dev/poll, kqueue(2), select(2), poll(2),
47 epoll(4), and evports. The internal event mechanism is completely
48 independent of the exposed event API, and a simple update of Libevent can
49 provide new functionality without having to redesign the applications. As a
50 result, Libevent allows for portable application development and provides
51 the most scalable event notification mechanism available on an operating
52 system. Libevent can also be used for multithreaded programs. Libevent
53 should compile on Linux, *BSD, Mac OS X, Solaris and, Windows.
54
55 @section usage Standard usage
56
57 Every program that uses Libevent must include the <event2/event.h>
58 header, and pass the -levent flag to the linker. (You can instead link
59 -levent_core if you only want the main event and buffered IO-based code,
60 and don't want to link any protocol code.)
61
62 @section setup Library setup
63
64 Before you call any other Libevent functions, you need to set up the
65 library. If you're going to use Libevent from multiple threads in a
66 multithreaded application, you need to initialize thread support --
67 typically by using evthread_use_pthreads() or
68 evthread_use_windows_threads(). See <event2/thread.h> for more
69 information.
70
71 This is also the point where you can replace Libevent's memory
72 management functions with event_set_mem_functions, and enable debug mode
73 with event_enable_debug_mode().
74
75 @section base Creating an event base
76
77 Next, you need to create an event_base structure, using event_base_new()
78 or event_base_new_with_config(). The event_base is responsible for
79 keeping track of which events are "pending" (that is to say, being
80 watched to see if they become active) and which events are "active".
81 Every event is associated with a single event_base.
82
83 @section event Event notification
84
85 For each file descriptor that you wish to monitor, you must create an
86 event structure with event_new(). (You may also declare an event
87 structure and call event_assign() to initialize the members of the
88 structure.) To enable notification, you add the structure to the list
89 of monitored events by calling event_add(). The event structure must
90 remain allocated as long as it is active, so it should generally be
91 allocated on the heap.
92
93 @section loop Dispatching events.
94
95 Finally, you call event_base_dispatch() to loop and dispatch events.
96 You can also use event_base_loop() for more fine-grained control.
97
98 Currently, only one thread can be dispatching a given event_base at a
99 time. If you want to run events in multiple threads at once, you can
100 either have a single event_base whose events add work to a work queue,
101 or you can create multiple event_base objects.
102
103 @section bufferevent I/O Buffers
104
105 Libevent provides a buffered I/O abstraction on top of the regular event
106 callbacks. This abstraction is called a bufferevent. A bufferevent
107 provides input and output buffers that get filled and drained
108 automatically. The user of a buffered event no longer deals directly
109 with the I/O, but instead is reading from input and writing to output
110 buffers.
111
112 Once initialized via bufferevent_socket_new(), the bufferevent structure
113 can be used repeatedly with bufferevent_enable() and
114 bufferevent_disable(). Instead of reading and writing directly to a
115 socket, you would call bufferevent_read() and bufferevent_write().
116
117 When read enabled the bufferevent will try to read from the file descriptor
118 and call the read callback. The write callback is executed whenever the
119 output buffer is drained below the write low watermark, which is 0 by
120 default.
121
122 See <event2/bufferevent*.h> for more information.
123
124 @section timers Timers
125
126 Libevent can also be used to create timers that invoke a callback after a
127 certain amount of time has expired. The evtimer_new() macro returns
128 an event struct to use as a timer. To activate the timer, call
129 evtimer_add(). Timers can be deactivated by calling evtimer_del().
130 (These macros are thin wrappers around event_new(), event_add(),
131 and event_del(); you can also use those instead.)
132
133 @section evdns Asynchronous DNS resolution
134
135 Libevent provides an asynchronous DNS resolver that should be used instead
136 of the standard DNS resolver functions. See the <event2/dns.h>
137 functions for more detail.
138
139 @section evhttp Event-driven HTTP servers
140
141 Libevent provides a very simple event-driven HTTP server that can be
142 embedded in your program and used to service HTTP requests.
143
144 To use this capability, you need to include the <event2/http.h> header in your
145 program. See that header for more information.
146
147 @section evrpc A framework for RPC servers and clients
148
149 Libevent provides a framework for creating RPC servers and clients. It
150 takes care of marshaling and unmarshaling all data structures.
151
152 @section api API Reference
153
154 To browse the complete documentation of the libevent API, click on any of
155 the following links.
156
157 event2/event.h
158 The primary libevent header
159
160 event2/thread.h
161 Functions for use by multithreaded programs
162
163 event2/buffer.h and event2/bufferevent.h
164 Buffer management for network reading and writing
165
166 event2/util.h
167 Utility functions for portable nonblocking network code
168
169 event2/dns.h
170 Asynchronous DNS resolution
171
172 event2/http.h
173 An embedded libevent-based HTTP server
174
175 event2/rpc.h
176 A framework for creating RPC servers and clients
177
178 */
179
180/** @file event2/event.h
181
182 Core functions for waiting for and receiving events, and using event bases.
183*/
184
185#include <event2/visibility.h>
186
187#ifdef __cplusplus
188extern "C" {
189#endif
190
191#include <event2/event-config.h>
192#ifdef EVENT__HAVE_SYS_TYPES_H
193#include <sys/types.h>
194#endif
195#ifdef EVENT__HAVE_SYS_TIME_H
196#include <sys/time.h>
197#endif
198
199#include <stdio.h>
200
201/* For int types. */
202#include <event2/util.h>
203
204/**
205 * Structure to hold information and state for a Libevent dispatch loop.
206 *
207 * The event_base lies at the center of Libevent; every application will
208 * have one. It keeps track of all pending and active events, and
209 * notifies your application of the active ones.
210 *
211 * This is an opaque structure; you can allocate one using
212 * event_base_new() or event_base_new_with_config().
213 *
214 * @see event_base_new(), event_base_free(), event_base_loop(),
215 * event_base_new_with_config()
216 */
217struct event_base
218#ifdef EVENT_IN_DOXYGEN_
219{/*Empty body so that doxygen will generate documentation here.*/}
220#endif
221;
222
223/**
224 * @struct event
225 *
226 * Structure to represent a single event.
227 *
228 * An event can have some underlying condition it represents: a socket
229 * becoming readable or writeable (or both), or a signal becoming raised.
230 * (An event that represents no underlying condition is still useful: you
231 * can use one to implement a timer, or to communicate between threads.)
232 *
233 * Generally, you can create events with event_new(), then make them
234 * pending with event_add(). As your event_base runs, it will run the
235 * callbacks of an events whose conditions are triggered. When you
236 * longer want the event, free it with event_free().
237 *
238 * In more depth:
239 *
240 * An event may be "pending" (one whose condition we are watching),
241 * "active" (one whose condition has triggered and whose callback is about
242 * to run), neither, or both. Events come into existence via
243 * event_assign() or event_new(), and are then neither active nor pending.
244 *
245 * To make an event pending, pass it to event_add(). When doing so, you
246 * can also set a timeout for the event.
247 *
248 * Events become active during an event_base_loop() call when either their
249 * condition has triggered, or when their timeout has elapsed. You can
250 * also activate an event manually using event_active(). The even_base
251 * loop will run the callbacks of active events; after it has done so, it
252 * marks them as no longer active.
253 *
254 * You can make an event non-pending by passing it to event_del(). This
255 * also makes the event non-active.
256 *
257 * Events can be "persistent" or "non-persistent". A non-persistent event
258 * becomes non-pending as soon as it is triggered: thus, it only runs at
259 * most once per call to event_add(). A persistent event remains pending
260 * even when it becomes active: you'll need to event_del() it manually in
261 * order to make it non-pending. When a persistent event with a timeout
262 * becomes active, its timeout is reset: this means you can use persistent
263 * events to implement periodic timeouts.
264 *
265 * This should be treated as an opaque structure; you should never read or
266 * write any of its fields directly. For backward compatibility with old
267 * code, it is defined in the event2/event_struct.h header; including this
268 * header may make your code incompatible with other versions of Libevent.
269 *
270 * @see event_new(), event_free(), event_assign(), event_get_assignment(),
271 * event_add(), event_del(), event_active(), event_pending(),
272 * event_get_fd(), event_get_base(), event_get_events(),
273 * event_get_callback(), event_get_callback_arg(),
274 * event_priority_set()
275 */
276struct event
277#ifdef EVENT_IN_DOXYGEN_
278{/*Empty body so that doxygen will generate documentation here.*/}
279#endif
280;
281
282/**
283 * Configuration for an event_base.
284 *
285 * There are many options that can be used to alter the behavior and
286 * implementation of an event_base. To avoid having to pass them all in a
287 * complex many-argument constructor, we provide an abstract data type
288 * wrhere you set up configation information before passing it to
289 * event_base_new_with_config().
290 *
291 * @see event_config_new(), event_config_free(), event_base_new_with_config(),
292 * event_config_avoid_method(), event_config_require_features(),
293 * event_config_set_flag(), event_config_set_num_cpus_hint()
294 */
295struct event_config
296#ifdef EVENT_IN_DOXYGEN_
297{/*Empty body so that doxygen will generate documentation here.*/}
298#endif
299;
300
301/**
302 * Enable some relatively expensive debugging checks in Libevent that
303 * would normally be turned off. Generally, these checks cause code that
304 * would otherwise crash mysteriously to fail earlier with an assertion
305 * failure. Note that this method MUST be called before any events or
306 * event_bases have been created.
307 *
308 * Debug mode can currently catch the following errors:
309 * An event is re-assigned while it is added
310 * Any function is called on a non-assigned event
311 *
312 * Note that debugging mode uses memory to track every event that has been
313 * initialized (via event_assign, event_set, or event_new) but not yet
314 * released (via event_free or event_debug_unassign). If you want to use
315 * debug mode, and you find yourself running out of memory, you will need
316 * to use event_debug_unassign to explicitly stop tracking events that
317 * are no longer considered set-up.
318 *
319 * @see event_debug_unassign()
320 */
321EVENT2_EXPORT_SYMBOL
322void event_enable_debug_mode(void);
323
324/**
325 * When debugging mode is enabled, informs Libevent that an event should no
326 * longer be considered as assigned. When debugging mode is not enabled, does
327 * nothing.
328 *
329 * This function must only be called on a non-added event.
330 *
331 * @see event_enable_debug_mode()
332 */
333EVENT2_EXPORT_SYMBOL
334void event_debug_unassign(struct event *);
335
336/**
337 * Create and return a new event_base to use with the rest of Libevent.
338 *
339 * @return a new event_base on success, or NULL on failure.
340 *
341 * @see event_base_free(), event_base_new_with_config()
342 */
343EVENT2_EXPORT_SYMBOL
344struct event_base *event_base_new(void);
345
346/**
347 Reinitialize the event base after a fork
348
349 Some event mechanisms do not survive across fork. The event base needs
350 to be reinitialized with the event_reinit() function.
351
352 @param base the event base that needs to be re-initialized
353 @return 0 if successful, or -1 if some events could not be re-added.
354 @see event_base_new()
355*/
356EVENT2_EXPORT_SYMBOL
357int event_reinit(struct event_base *base);
358
359/**
360 Event dispatching loop
361
362 This loop will run the event base until either there are no more pending or
363 active, or until something calls event_base_loopbreak() or
364 event_base_loopexit().
365
366 @param base the event_base structure returned by event_base_new() or
367 event_base_new_with_config()
368 @return 0 if successful, -1 if an error occurred, or 1 if we exited because
369 no events were pending or active.
370 @see event_base_loop()
371 */
372EVENT2_EXPORT_SYMBOL
373int event_base_dispatch(struct event_base *);
374
375/**
376 Get the kernel event notification mechanism used by Libevent.
377
378 @param eb the event_base structure returned by event_base_new()
379 @return a string identifying the kernel event mechanism (kqueue, epoll, etc.)
380 */
381EVENT2_EXPORT_SYMBOL
382const char *event_base_get_method(const struct event_base *);
383
384/**
385 Gets all event notification mechanisms supported by Libevent.
386
387 This functions returns the event mechanism in order preferred by
388 Libevent. Note that this list will include all backends that
389 Libevent has compiled-in support for, and will not necessarily check
390 your OS to see whether it has the required resources.
391
392 @return an array with pointers to the names of support methods.
393 The end of the array is indicated by a NULL pointer. If an
394 error is encountered NULL is returned.
395*/
396EVENT2_EXPORT_SYMBOL
397const char **event_get_supported_methods(void);
398
399/** Query the current monotonic time from a the timer for a struct
400 * event_base.
401 */
402EVENT2_EXPORT_SYMBOL
403int event_gettime_monotonic(struct event_base *base, struct timeval *tp);
404
405/**
406 @name event type flag
407
408 Flags to pass to event_base_get_num_events() to specify the kinds of events
409 we want to aggregate counts for
410*/
411/**@{*/
412/** count the number of active events, which have been triggered.*/
413#define EVENT_BASE_COUNT_ACTIVE 1U
414/** count the number of virtual events, which is used to represent an internal
415 * condition, other than a pending event, that keeps the loop from exiting. */
416#define EVENT_BASE_COUNT_VIRTUAL 2U
417/** count the number of events which have been added to event base, including
418 * internal events. */
419#define EVENT_BASE_COUNT_ADDED 4U
420/**@}*/
421
422/**
423 Gets the number of events in event_base, as specified in the flags.
424
425 Since event base has some internal events added to make some of its
426 functionalities work, EVENT_BASE_COUNT_ADDED may return more than the
427 number of events you added using event_add().
428
429 If you pass EVENT_BASE_COUNT_ACTIVE and EVENT_BASE_COUNT_ADDED together, an
430 active event will be counted twice. However, this might not be the case in
431 future libevent versions. The return value is an indication of the work
432 load, but the user shouldn't rely on the exact value as this may change in
433 the future.
434
435 @param eb the event_base structure returned by event_base_new()
436 @param flags a bitwise combination of the kinds of events to aggregate
437 counts for
438 @return the number of events specified in the flags
439*/
440EVENT2_EXPORT_SYMBOL
441int event_base_get_num_events(struct event_base *, unsigned int);
442
443/**
444 Get the maximum number of events in a given event_base as specified in the
445 flags.
446
447 @param eb the event_base structure returned by event_base_new()
448 @param flags a bitwise combination of the kinds of events to aggregate
449 counts for
450 @param clear option used to reset the maximum count.
451 @return the number of events specified in the flags
452 */
453EVENT2_EXPORT_SYMBOL
454int event_base_get_max_events(struct event_base *, unsigned int, int);
455
456/**
457 Allocates a new event configuration object.
458
459 The event configuration object can be used to change the behavior of
460 an event base.
461
462 @return an event_config object that can be used to store configuration, or
463 NULL if an error is encountered.
464 @see event_base_new_with_config(), event_config_free(), event_config
465*/
466EVENT2_EXPORT_SYMBOL
467struct event_config *event_config_new(void);
468
469/**
470 Deallocates all memory associated with an event configuration object
471
472 @param cfg the event configuration object to be freed.
473*/
474EVENT2_EXPORT_SYMBOL
475void event_config_free(struct event_config *cfg);
476
477/**
478 Enters an event method that should be avoided into the configuration.
479
480 This can be used to avoid event mechanisms that do not support certain
481 file descriptor types, or for debugging to avoid certain event
482 mechanisms. An application can make use of multiple event bases to
483 accommodate incompatible file descriptor types.
484
485 @param cfg the event configuration object
486 @param method the name of the event method to avoid
487 @return 0 on success, -1 on failure.
488*/
489EVENT2_EXPORT_SYMBOL
490int event_config_avoid_method(struct event_config *cfg, const char *method);
491
492/**
493 A flag used to describe which features an event_base (must) provide.
494
495 Because of OS limitations, not every Libevent backend supports every
496 possible feature. You can use this type with
497 event_config_require_features() to tell Libevent to only proceed if your
498 event_base implements a given feature, and you can receive this type from
499 event_base_get_features() to see which features are available.
500*/
501enum event_method_feature {
502 /** Require an event method that allows edge-triggered events with EV_ET. */
503 EV_FEATURE_ET = 0x01,
504 /** Require an event method where having one event triggered among
505 * many is [approximately] an O(1) operation. This excludes (for
506 * example) select and poll, which are approximately O(N) for N
507 * equal to the total number of possible events. */
508 EV_FEATURE_O1 = 0x02,
509 /** Require an event method that allows file descriptors as well as
510 * sockets. */
511 EV_FEATURE_FDS = 0x04,
512 /** Require an event method that allows you to use EV_CLOSED to detect
513 * connection close without the necessity of reading all the pending data.
514 *
515 * Methods that do support EV_CLOSED may not be able to provide support on
516 * all kernel versions.
517 **/
518 EV_FEATURE_EARLY_CLOSE = 0x08
519};
520
521/**
522 A flag passed to event_config_set_flag().
523
524 These flags change the behavior of an allocated event_base.
525
526 @see event_config_set_flag(), event_base_new_with_config(),
527 event_method_feature
528 */
529enum event_base_config_flag {
530 /** Do not allocate a lock for the event base, even if we have
531 locking set up.
532
533 Setting this option will make it unsafe and nonfunctional to call
534 functions on the base concurrently from multiple threads.
535 */
536 EVENT_BASE_FLAG_NOLOCK = 0x01,
537 /** Do not check the EVENT_* environment variables when configuring
538 an event_base */
539 EVENT_BASE_FLAG_IGNORE_ENV = 0x02,
540 /** Windows only: enable the IOCP dispatcher at startup
541
542 If this flag is set then bufferevent_socket_new() and
543 evconn_listener_new() will use IOCP-backed implementations
544 instead of the usual select-based one on Windows.
545 */
546 EVENT_BASE_FLAG_STARTUP_IOCP = 0x04,
547 /** Instead of checking the current time every time the event loop is
548 ready to run timeout callbacks, check after each timeout callback.
549 */
550 EVENT_BASE_FLAG_NO_CACHE_TIME = 0x08,
551
552 /** If we are using the epoll backend, this flag says that it is
553 safe to use Libevent's internal change-list code to batch up
554 adds and deletes in order to try to do as few syscalls as
555 possible. Setting this flag can make your code run faster, but
556 it may trigger a Linux bug: it is not safe to use this flag
557 if you have any fds cloned by dup() or its variants. Doing so
558 will produce strange and hard-to-diagnose bugs.
559
560 This flag can also be activated by setting the
561 EVENT_EPOLL_USE_CHANGELIST environment variable.
562
563 This flag has no effect if you wind up using a backend other than
564 epoll.
565 */
566 EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST = 0x10,
567
568 /** Ordinarily, Libevent implements its time and timeout code using
569 the fastest monotonic timer that we have. If this flag is set,
570 however, we use less efficient more precise timer, assuming one is
571 present.
572 */
573 EVENT_BASE_FLAG_PRECISE_TIMER = 0x20
574};
575
576/**
577 Return a bitmask of the features implemented by an event base. This
578 will be a bitwise OR of one or more of the values of
579 event_method_feature
580
581 @see event_method_feature
582 */
583EVENT2_EXPORT_SYMBOL
584int event_base_get_features(const struct event_base *base);
585
586/**
587 Enters a required event method feature that the application demands.
588
589 Note that not every feature or combination of features is supported
590 on every platform. Code that requests features should be prepared
591 to handle the case where event_base_new_with_config() returns NULL, as in:
592 <pre>
593 event_config_require_features(cfg, EV_FEATURE_ET);
594 base = event_base_new_with_config(cfg);
595 if (base == NULL) {
596 // We can't get edge-triggered behavior here.
597 event_config_require_features(cfg, 0);
598 base = event_base_new_with_config(cfg);
599 }
600 </pre>
601
602 @param cfg the event configuration object
603 @param feature a bitfield of one or more event_method_feature values.
604 Replaces values from previous calls to this function.
605 @return 0 on success, -1 on failure.
606 @see event_method_feature, event_base_new_with_config()
607*/
608EVENT2_EXPORT_SYMBOL
609int event_config_require_features(struct event_config *cfg, int feature);
610
611/**
612 * Sets one or more flags to configure what parts of the eventual event_base
613 * will be initialized, and how they'll work.
614 *
615 * @see event_base_config_flags, event_base_new_with_config()
616 **/
617EVENT2_EXPORT_SYMBOL
618int event_config_set_flag(struct event_config *cfg, int flag);
619
620/**
621 * Records a hint for the number of CPUs in the system. This is used for
622 * tuning thread pools, etc, for optimal performance. In Libevent 2.0,
623 * it is only on Windows, and only when IOCP is in use.
624 *
625 * @param cfg the event configuration object
626 * @param cpus the number of cpus
627 * @return 0 on success, -1 on failure.
628 */
629EVENT2_EXPORT_SYMBOL
630int event_config_set_num_cpus_hint(struct event_config *cfg, int cpus);
631
632/**
633 * Record an interval and/or a number of callbacks after which the event base
634 * should check for new events. By default, the event base will run as many
635 * events are as activated at the higest activated priority before checking
636 * for new events. If you configure it by setting max_interval, it will check
637 * the time after each callback, and not allow more than max_interval to
638 * elapse before checking for new events. If you configure it by setting
639 * max_callbacks to a value >= 0, it will run no more than max_callbacks
640 * callbacks before checking for new events.
641 *
642 * This option can decrease the latency of high-priority events, and
643 * avoid priority inversions where multiple low-priority events keep us from
644 * polling for high-priority events, but at the expense of slightly decreasing
645 * the throughput. Use it with caution!
646 *
647 * @param cfg The event_base configuration object.
648 * @param max_interval An interval after which Libevent should stop running
649 * callbacks and check for more events, or NULL if there should be
650 * no such interval.
651 * @param max_callbacks A number of callbacks after which Libevent should
652 * stop running callbacks and check for more events, or -1 if there
653 * should be no such limit.
654 * @param min_priority A priority below which max_interval and max_callbacks
655 * should not be enforced. If this is set to 0, they are enforced
656 * for events of every priority; if it's set to 1, they're enforced
657 * for events of priority 1 and above, and so on.
658 * @return 0 on success, -1 on failure.
659 **/
660EVENT2_EXPORT_SYMBOL
661int event_config_set_max_dispatch_interval(struct event_config *cfg,
662 const struct timeval *max_interval, int max_callbacks,
663 int min_priority);
664
665/**
666 Initialize the event API.
667
668 Use event_base_new_with_config() to initialize a new event base, taking
669 the specified configuration under consideration. The configuration object
670 can currently be used to avoid certain event notification mechanisms.
671
672 @param cfg the event configuration object
673 @return an initialized event_base that can be used to registering events,
674 or NULL if no event base can be created with the requested event_config.
675 @see event_base_new(), event_base_free(), event_init(), event_assign()
676*/
677EVENT2_EXPORT_SYMBOL
678struct event_base *event_base_new_with_config(const struct event_config *);
679
680/**
681 Deallocate all memory associated with an event_base, and free the base.
682
683 Note that this function will not close any fds or free any memory passed
684 to event_new as the argument to callback.
685
686 If there are any pending finalizer callbacks, this function will invoke
687 them.
688
689 @param eb an event_base to be freed
690 */
691EVENT2_EXPORT_SYMBOL
692void event_base_free(struct event_base *);
693
694/**
695 As event_free, but do not run finalizers.
696
697 THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
698 BECOMES STABLE.
699 */
700EVENT2_EXPORT_SYMBOL
701void event_base_free_nofinalize(struct event_base *);
702
703/** @name Log severities
704 */
705/**@{*/
706#define EVENT_LOG_DEBUG 0
707#define EVENT_LOG_MSG 1
708#define EVENT_LOG_WARN 2
709#define EVENT_LOG_ERR 3
710/**@}*/
711
712/* Obsolete names: these are deprecated, but older programs might use them.
713 * They violate the reserved-identifier namespace. */
714#define _EVENT_LOG_DEBUG EVENT_LOG_DEBUG
715#define _EVENT_LOG_MSG EVENT_LOG_MSG
716#define _EVENT_LOG_WARN EVENT_LOG_WARN
717#define _EVENT_LOG_ERR EVENT_LOG_ERR
718
719/**
720 A callback function used to intercept Libevent's log messages.
721
722 @see event_set_log_callback
723 */
724typedef void (*event_log_cb)(int severity, const char *msg);
725/**
726 Redirect Libevent's log messages.
727
728 @param cb a function taking two arguments: an integer severity between
729 EVENT_LOG_DEBUG and EVENT_LOG_ERR, and a string. If cb is NULL,
730 then the default log is used.
731
732 NOTE: The function you provide *must not* call any other libevent
733 functionality. Doing so can produce undefined behavior.
734 */
735EVENT2_EXPORT_SYMBOL
736void event_set_log_callback(event_log_cb cb);
737
738/**
739 A function to be called if Libevent encounters a fatal internal error.
740
741 @see event_set_fatal_callback
742 */
743typedef void (*event_fatal_cb)(int err);
744
745/**
746 Override Libevent's behavior in the event of a fatal internal error.
747
748 By default, Libevent will call exit(1) if a programming error makes it
749 impossible to continue correct operation. This function allows you to supply
750 another callback instead. Note that if the function is ever invoked,
751 something is wrong with your program, or with Libevent: any subsequent calls
752 to Libevent may result in undefined behavior.
753
754 Libevent will (almost) always log an EVENT_LOG_ERR message before calling
755 this function; look at the last log message to see why Libevent has died.
756 */
757EVENT2_EXPORT_SYMBOL
758void event_set_fatal_callback(event_fatal_cb cb);
759
760#define EVENT_DBG_ALL 0xffffffffu
761#define EVENT_DBG_NONE 0
762
763/**
764 Turn on debugging logs and have them sent to the default log handler.
765
766 This is a global setting; if you are going to call it, you must call this
767 before any calls that create an event-base. You must call it before any
768 multithreaded use of Libevent.
769
770 Debug logs are verbose.
771
772 @param which Controls which debug messages are turned on. This option is
773 unused for now; for forward compatibility, you must pass in the constant
774 "EVENT_DBG_ALL" to turn debugging logs on, or "EVENT_DBG_NONE" to turn
775 debugging logs off.
776 */
777EVENT2_EXPORT_SYMBOL
778void event_enable_debug_logging(ev_uint32_t which);
779
780/**
781 Associate a different event base with an event.
782
783 The event to be associated must not be currently active or pending.
784
785 @param eb the event base
786 @param ev the event
787 @return 0 on success, -1 on failure.
788 */
789EVENT2_EXPORT_SYMBOL
790int event_base_set(struct event_base *, struct event *);
791
792/** @name Loop flags
793
794 These flags control the behavior of event_base_loop().
795 */
796/**@{*/
797/** Block until we have an active event, then exit once all active events
798 * have had their callbacks run. */
799#define EVLOOP_ONCE 0x01
800/** Do not block: see which events are ready now, run the callbacks
801 * of the highest-priority ones, then exit. */
802#define EVLOOP_NONBLOCK 0x02
803/** Do not exit the loop because we have no pending events. Instead, keep
804 * running until event_base_loopexit() or event_base_loopbreak() makes us
805 * stop.
806 */
807#define EVLOOP_NO_EXIT_ON_EMPTY 0x04
808/**@}*/
809
810/**
811 Wait for events to become active, and run their callbacks.
812
813 This is a more flexible version of event_base_dispatch().
814
815 By default, this loop will run the event base until either there are no more
816 pending or active events, or until something calls event_base_loopbreak() or
817 event_base_loopexit(). You can override this behavior with the 'flags'
818 argument.
819
820 @param eb the event_base structure returned by event_base_new() or
821 event_base_new_with_config()
822 @param flags any combination of EVLOOP_ONCE | EVLOOP_NONBLOCK
823 @return 0 if successful, -1 if an error occurred, or 1 if we exited because
824 no events were pending or active.
825 @see event_base_loopexit(), event_base_dispatch(), EVLOOP_ONCE,
826 EVLOOP_NONBLOCK
827 */
828EVENT2_EXPORT_SYMBOL
829int event_base_loop(struct event_base *, int);
830
831/**
832 Exit the event loop after the specified time
833
834 The next event_base_loop() iteration after the given timer expires will
835 complete normally (handling all queued events) then exit without
836 blocking for events again.
837
838 Subsequent invocations of event_base_loop() will proceed normally.
839
840 @param eb the event_base structure returned by event_init()
841 @param tv the amount of time after which the loop should terminate,
842 or NULL to exit after running all currently active events.
843 @return 0 if successful, or -1 if an error occurred
844 @see event_base_loopbreak()
845 */
846EVENT2_EXPORT_SYMBOL
847int event_base_loopexit(struct event_base *, const struct timeval *);
848
849/**
850 Abort the active event_base_loop() immediately.
851
852 event_base_loop() will abort the loop after the next event is completed;
853 event_base_loopbreak() is typically invoked from this event's callback.
854 This behavior is analogous to the "break;" statement.
855
856 Subsequent invocations of event_base_loop() will proceed normally.
857
858 @param eb the event_base structure returned by event_init()
859 @return 0 if successful, or -1 if an error occurred
860 @see event_base_loopexit()
861 */
862EVENT2_EXPORT_SYMBOL
863int event_base_loopbreak(struct event_base *);
864
865/**
866 Tell the active event_base_loop() to scan for new events immediately.
867
868 Calling this function makes the currently active event_base_loop()
869 start the loop over again (scanning for new events) after the current
870 event callback finishes. If the event loop is not running, this
871 function has no effect.
872
873 event_base_loopbreak() is typically invoked from this event's callback.
874 This behavior is analogous to the "continue;" statement.
875
876 Subsequent invocations of event loop will proceed normally.
877
878 @param eb the event_base structure returned by event_init()
879 @return 0 if successful, or -1 if an error occurred
880 @see event_base_loopbreak()
881 */
882EVENT2_EXPORT_SYMBOL
883int event_base_loopcontinue(struct event_base *);
884
885/**
886 Checks if the event loop was told to exit by event_base_loopexit().
887
888 This function will return true for an event_base at every point after
889 event_loopexit() is called, until the event loop is next entered.
890
891 @param eb the event_base structure returned by event_init()
892 @return true if event_base_loopexit() was called on this event base,
893 or 0 otherwise
894 @see event_base_loopexit()
895 @see event_base_got_break()
896 */
897EVENT2_EXPORT_SYMBOL
898int event_base_got_exit(struct event_base *);
899
900/**
901 Checks if the event loop was told to abort immediately by event_base_loopbreak().
902
903 This function will return true for an event_base at every point after
904 event_base_loopbreak() is called, until the event loop is next entered.
905
906 @param eb the event_base structure returned by event_init()
907 @return true if event_base_loopbreak() was called on this event base,
908 or 0 otherwise
909 @see event_base_loopbreak()
910 @see event_base_got_exit()
911 */
912EVENT2_EXPORT_SYMBOL
913int event_base_got_break(struct event_base *);
914
915/**
916 * @name event flags
917 *
918 * Flags to pass to event_new(), event_assign(), event_pending(), and
919 * anything else with an argument of the form "short events"
920 */
921/**@{*/
922/** Indicates that a timeout has occurred. It's not necessary to pass
923 * this flag to event_for new()/event_assign() to get a timeout. */
924#define EV_TIMEOUT 0x01
925/** Wait for a socket or FD to become readable */
926#define EV_READ 0x02
927/** Wait for a socket or FD to become writeable */
928#define EV_WRITE 0x04
929/** Wait for a POSIX signal to be raised*/
930#define EV_SIGNAL 0x08
931/**
932 * Persistent event: won't get removed automatically when activated.
933 *
934 * When a persistent event with a timeout becomes activated, its timeout
935 * is reset to 0.
936 */
937#define EV_PERSIST 0x10
938/** Select edge-triggered behavior, if supported by the backend. */
939#define EV_ET 0x20
940/**
941 * If this option is provided, then event_del() will not block in one thread
942 * while waiting for the event callback to complete in another thread.
943 *
944 * To use this option safely, you may need to use event_finalize() or
945 * event_free_finalize() in order to safely tear down an event in a
946 * multithreaded application. See those functions for more information.
947 *
948 * THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
949 * BECOMES STABLE.
950 **/
951#define EV_FINALIZE 0x40
952/**
953 * Detects connection close events. You can use this to detect when a
954 * connection has been closed, without having to read all the pending data
955 * from a connection.
956 *
957 * Not all backends support EV_CLOSED. To detect or require it, use the
958 * feature flag EV_FEATURE_EARLY_CLOSE.
959 **/
960#define EV_CLOSED 0x80
961/**@}*/
962
963/**
964 @name evtimer_* macros
965
966 Aliases for working with one-shot timer events */
967/**@{*/
968#define evtimer_assign(ev, b, cb, arg) \
969 event_assign((ev), (b), -1, 0, (cb), (arg))
970#define evtimer_new(b, cb, arg) event_new((b), -1, 0, (cb), (arg))
971#define evtimer_add(ev, tv) event_add((ev), (tv))
972#define evtimer_del(ev) event_del(ev)
973#define evtimer_pending(ev, tv) event_pending((ev), EV_TIMEOUT, (tv))
974#define evtimer_initialized(ev) event_initialized(ev)
975/**@}*/
976
977/**
978 @name evsignal_* macros
979
980 Aliases for working with signal events
981 */
982/**@{*/
983#define evsignal_add(ev, tv) event_add((ev), (tv))
984#define evsignal_assign(ev, b, x, cb, arg) \
985 event_assign((ev), (b), (x), EV_SIGNAL|EV_PERSIST, cb, (arg))
986#define evsignal_new(b, x, cb, arg) \
987 event_new((b), (x), EV_SIGNAL|EV_PERSIST, (cb), (arg))
988#define evsignal_del(ev) event_del(ev)
989#define evsignal_pending(ev, tv) event_pending((ev), EV_SIGNAL, (tv))
990#define evsignal_initialized(ev) event_initialized(ev)
991/**@}*/
992
993/**
994 A callback function for an event.
995
996 It receives three arguments:
997
998 @param fd An fd or signal
999 @param events One or more EV_* flags
1000 @param arg A user-supplied argument.
1001
1002 @see event_new()
1003 */
1004typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
1005
1006/**
1007 Return a value used to specify that the event itself must be used as the callback argument.
1008
1009 The function event_new() takes a callback argument which is passed
1010 to the event's callback function. To specify that the argument to be
1011 passed to the callback function is the event that event_new() returns,
1012 pass in the return value of event_self_cbarg() as the callback argument
1013 for event_new().
1014
1015 For example:
1016 <pre>
1017 struct event *ev = event_new(base, sock, events, callback, %event_self_cbarg());
1018 </pre>
1019
1020 For consistency with event_new(), it is possible to pass the return value
1021 of this function as the callback argument for event_assign() &ndash; this
1022 achieves the same result as passing the event in directly.
1023
1024 @return a value to be passed as the callback argument to event_new() or
1025 event_assign().
1026 @see event_new(), event_assign()
1027 */
1028EVENT2_EXPORT_SYMBOL
1029void *event_self_cbarg(void);
1030
1031/**
1032 Allocate and asssign a new event structure, ready to be added.
1033
1034 The function event_new() returns a new event that can be used in
1035 future calls to event_add() and event_del(). The fd and events
1036 arguments determine which conditions will trigger the event; the
1037 callback and callback_arg arguments tell Libevent what to do when the
1038 event becomes active.
1039
1040 If events contains one of EV_READ, EV_WRITE, or EV_READ|EV_WRITE, then
1041 fd is a file descriptor or socket that should get monitored for
1042 readiness to read, readiness to write, or readiness for either operation
1043 (respectively). If events contains EV_SIGNAL, then fd is a signal
1044 number to wait for. If events contains none of those flags, then the
1045 event can be triggered only by a timeout or by manual activation with
1046 event_active(): In this case, fd must be -1.
1047
1048 The EV_PERSIST flag can also be passed in the events argument: it makes
1049 event_add() persistent until event_del() is called.
1050
1051 The EV_ET flag is compatible with EV_READ and EV_WRITE, and supported
1052 only by certain backends. It tells Libevent to use edge-triggered
1053 events.
1054
1055 The EV_TIMEOUT flag has no effect here.
1056
1057 It is okay to have multiple events all listening on the same fds; but
1058 they must either all be edge-triggered, or all not be edge triggerd.
1059
1060 When the event becomes active, the event loop will run the provided
1061 callbuck function, with three arguments. The first will be the provided
1062 fd value. The second will be a bitfield of the events that triggered:
1063 EV_READ, EV_WRITE, or EV_SIGNAL. Here the EV_TIMEOUT flag indicates
1064 that a timeout occurred, and EV_ET indicates that an edge-triggered
1065 event occurred. The third event will be the callback_arg pointer that
1066 you provide.
1067
1068 @param base the event base to which the event should be attached.
1069 @param fd the file descriptor or signal to be monitored, or -1.
1070 @param events desired events to monitor: bitfield of EV_READ, EV_WRITE,
1071 EV_SIGNAL, EV_PERSIST, EV_ET.
1072 @param callback callback function to be invoked when the event occurs
1073 @param callback_arg an argument to be passed to the callback function
1074
1075 @return a newly allocated struct event that must later be freed with
1076 event_free().
1077 @see event_free(), event_add(), event_del(), event_assign()
1078 */
1079EVENT2_EXPORT_SYMBOL
1080struct event *event_new(struct event_base *, evutil_socket_t, short, event_callback_fn, void *);
1081
1082
1083/**
1084 Prepare a new, already-allocated event structure to be added.
1085
1086 The function event_assign() prepares the event structure ev to be used
1087 in future calls to event_add() and event_del(). Unlike event_new(), it
1088 doesn't allocate memory itself: it requires that you have already
1089 allocated a struct event, probably on the heap. Doing this will
1090 typically make your code depend on the size of the event structure, and
1091 thereby create incompatibility with future versions of Libevent.
1092
1093 The easiest way to avoid this problem is just to use event_new() and
1094 event_free() instead.
1095
1096 A slightly harder way to future-proof your code is to use
1097 event_get_struct_event_size() to determine the required size of an event
1098 at runtime.
1099
1100 Note that it is NOT safe to call this function on an event that is
1101 active or pending. Doing so WILL corrupt internal data structures in
1102 Libevent, and lead to strange, hard-to-diagnose bugs. You _can_ use
1103 event_assign to change an existing event, but only if it is not active
1104 or pending!
1105
1106 The arguments for this function, and the behavior of the events that it
1107 makes, are as for event_new().
1108
1109 @param ev an event struct to be modified
1110 @param base the event base to which ev should be attached.
1111 @param fd the file descriptor to be monitored
1112 @param events desired events to monitor; can be EV_READ and/or EV_WRITE
1113 @param callback callback function to be invoked when the event occurs
1114 @param callback_arg an argument to be passed to the callback function
1115
1116 @return 0 if success, or -1 on invalid arguments.
1117
1118 @see event_new(), event_add(), event_del(), event_base_once(),
1119 event_get_struct_event_size()
1120 */
1121EVENT2_EXPORT_SYMBOL
1122int event_assign(struct event *, struct event_base *, evutil_socket_t, short, event_callback_fn, void *);
1123
1124/**
1125 Deallocate a struct event * returned by event_new().
1126
1127 If the event is pending or active, first make it non-pending and
1128 non-active.
1129 */
1130EVENT2_EXPORT_SYMBOL
1131void event_free(struct event *);
1132
1133/**
1134 * Callback type for event_finalize and event_free_finalize().
1135 *
1136 * THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
1137 * BECOMES STABLE.
1138 *
1139 **/
1140typedef void (*event_finalize_callback_fn)(struct event *, void *);
1141/**
1142 @name Finalization functions
1143
1144 These functions are used to safely tear down an event in a multithreaded
1145 application. If you construct your events with EV_FINALIZE to avoid
1146 deadlocks, you will need a way to remove an event in the certainty that
1147 it will definitely not be running its callback when you deallocate it
1148 and its callback argument.
1149
1150 To do this, call one of event_finalize() or event_free_finalize with
1151 0 for its first argument, the event to tear down as its second argument,
1152 and a callback function as its third argument. The callback will be
1153 invoked as part of the event loop, with the event's priority.
1154
1155 After you call a finalizer function, event_add() and event_active() will
1156 no longer work on the event, and event_del() will produce a no-op. You
1157 must not try to change the event's fields with event_assign() or
1158 event_set() while the finalize callback is in progress. Once the
1159 callback has been invoked, you should treat the event structure as
1160 containing uninitialized memory.
1161
1162 The event_free_finalize() function frees the event after it's finalized;
1163 event_finalize() does not.
1164
1165 A finalizer callback must not make events pending or active. It must not
1166 add events, activate events, or attempt to "resucitate" the event being
1167 finalized in any way.
1168
1169 THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
1170 BECOMES STABLE.
1171
1172 @return 0 on succes, -1 on failure.
1173 */
1174/**@{*/
1175EVENT2_EXPORT_SYMBOL
1176int event_finalize(unsigned, struct event *, event_finalize_callback_fn);
1177EVENT2_EXPORT_SYMBOL
1178int event_free_finalize(unsigned, struct event *, event_finalize_callback_fn);
1179/**@}*/
1180
1181/**
1182 Schedule a one-time event
1183
1184 The function event_base_once() is similar to event_new(). However, it
1185 schedules a callback to be called exactly once, and does not require the
1186 caller to prepare an event structure.
1187
1188 Note that in Libevent 2.0 and earlier, if the event is never triggered, the
1189 internal memory used to hold it will never be freed. In Libevent 2.1,
1190 the internal memory will get freed by event_base_free() if the event
1191 is never triggered. The 'arg' value, however, will not get freed in either
1192 case--you'll need to free that on your own if you want it to go away.
1193
1194 @param base an event_base
1195 @param fd a file descriptor to monitor, or -1 for no fd.
1196 @param events event(s) to monitor; can be any of EV_READ |
1197 EV_WRITE, or EV_TIMEOUT
1198 @param callback callback function to be invoked when the event occurs
1199 @param arg an argument to be passed to the callback function
1200 @param timeout the maximum amount of time to wait for the event. NULL
1201 makes an EV_READ/EV_WRITE event make forever; NULL makes an
1202 EV_TIMEOUT event succees immediately.
1203 @return 0 if successful, or -1 if an error occurred
1204 */
1205EVENT2_EXPORT_SYMBOL
1206int event_base_once(struct event_base *, evutil_socket_t, short, event_callback_fn, void *, const struct timeval *);
1207
1208/**
1209 Add an event to the set of pending events.
1210
1211 The function event_add() schedules the execution of the event 'ev' when the
1212 condition specified by event_assign() or event_new() occurs, or when the time
1213 specified in timeout has elapesed. If atimeout is NULL, no timeout
1214 occurs and the function will only be
1215 called if a matching event occurs. The event in the
1216 ev argument must be already initialized by event_assign() or event_new()
1217 and may not be used
1218 in calls to event_assign() until it is no longer pending.
1219
1220 If the event in the ev argument already has a scheduled timeout, calling
1221 event_add() replaces the old timeout with the new one if tv is non-NULL.
1222
1223 @param ev an event struct initialized via event_assign() or event_new()
1224 @param timeout the maximum amount of time to wait for the event, or NULL
1225 to wait forever
1226 @return 0 if successful, or -1 if an error occurred
1227 @see event_del(), event_assign(), event_new()
1228 */
1229EVENT2_EXPORT_SYMBOL
1230int event_add(struct event *ev, const struct timeval *timeout);
1231
1232/**
1233 Remove a timer from a pending event without removing the event itself.
1234
1235 If the event has a scheduled timeout, this function unschedules it but
1236 leaves the event otherwise pending.
1237
1238 @param ev an event struct initialized via event_assign() or event_new()
1239 @return 0 on success, or -1 if an error occurrect.
1240*/
1241EVENT2_EXPORT_SYMBOL
1242int event_remove_timer(struct event *ev);
1243
1244/**
1245 Remove an event from the set of monitored events.
1246
1247 The function event_del() will cancel the event in the argument ev. If the
1248 event has already executed or has never been added the call will have no
1249 effect.
1250
1251 @param ev an event struct to be removed from the working set
1252 @return 0 if successful, or -1 if an error occurred
1253 @see event_add()
1254 */
1255EVENT2_EXPORT_SYMBOL
1256int event_del(struct event *);
1257
1258/**
1259 As event_del(), but never blocks while the event's callback is running
1260 in another thread, even if the event was constructed without the
1261 EV_FINALIZE flag.
1262
1263 THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
1264 BECOMES STABLE.
1265 */
1266EVENT2_EXPORT_SYMBOL
1267int event_del_noblock(struct event *ev);
1268/**
1269 As event_del(), but always blocks while the event's callback is running
1270 in another thread, even if the event was constructed with the
1271 EV_FINALIZE flag.
1272
1273 THIS IS AN EXPERIMENTAL API. IT MIGHT CHANGE BEFORE THE LIBEVENT 2.1 SERIES
1274 BECOMES STABLE.
1275 */
1276EVENT2_EXPORT_SYMBOL
1277int event_del_block(struct event *ev);
1278
1279/**
1280 Make an event active.
1281
1282 You can use this function on a pending or a non-pending event to make it
1283 active, so that its callback will be run by event_base_dispatch() or
1284 event_base_loop().
1285
1286 One common use in multithreaded programs is to wake the thread running
1287 event_base_loop() from another thread.
1288
1289 @param ev an event to make active.
1290 @param res a set of flags to pass to the event's callback.
1291 @param ncalls an obsolete argument: this is ignored.
1292 **/
1293EVENT2_EXPORT_SYMBOL
1294void event_active(struct event *ev, int res, short ncalls);
1295
1296/**
1297 Checks if a specific event is pending or scheduled.
1298
1299 @param ev an event struct previously passed to event_add()
1300 @param events the requested event type; any of EV_TIMEOUT|EV_READ|
1301 EV_WRITE|EV_SIGNAL
1302 @param tv if this field is not NULL, and the event has a timeout,
1303 this field is set to hold the time at which the timeout will
1304 expire.
1305
1306 @return true if the event is pending on any of the events in 'what', (that
1307 is to say, it has been added), or 0 if the event is not added.
1308 */
1309EVENT2_EXPORT_SYMBOL
1310int event_pending(const struct event *ev, short events, struct timeval *tv);
1311
1312/**
1313 If called from within the callback for an event, returns that event.
1314
1315 The behavior of this function is not defined when called from outside the
1316 callback function for an event.
1317 */
1318EVENT2_EXPORT_SYMBOL
1319struct event *event_base_get_running_event(struct event_base *base);
1320
1321/**
1322 Test if an event structure might be initialized.
1323
1324 The event_initialized() function can be used to check if an event has been
1325 initialized.
1326
1327 Warning: This function is only useful for distinguishing a a zeroed-out
1328 piece of memory from an initialized event, it can easily be confused by
1329 uninitialized memory. Thus, it should ONLY be used to distinguish an
1330 initialized event from zero.
1331
1332 @param ev an event structure to be tested
1333 @return 1 if the structure might be initialized, or 0 if it has not been
1334 initialized
1335 */
1336EVENT2_EXPORT_SYMBOL
1337int event_initialized(const struct event *ev);
1338
1339/**
1340 Get the signal number assigned to a signal event
1341*/
1342#define event_get_signal(ev) ((int)event_get_fd(ev))
1343
1344/**
1345 Get the socket or signal assigned to an event, or -1 if the event has
1346 no socket.
1347*/
1348EVENT2_EXPORT_SYMBOL
1349evutil_socket_t event_get_fd(const struct event *ev);
1350
1351/**
1352 Get the event_base associated with an event.
1353*/
1354EVENT2_EXPORT_SYMBOL
1355struct event_base *event_get_base(const struct event *ev);
1356
1357/**
1358 Return the events (EV_READ, EV_WRITE, etc) assigned to an event.
1359*/
1360EVENT2_EXPORT_SYMBOL
1361short event_get_events(const struct event *ev);
1362
1363/**
1364 Return the callback assigned to an event.
1365*/
1366EVENT2_EXPORT_SYMBOL
1367event_callback_fn event_get_callback(const struct event *ev);
1368
1369/**
1370 Return the callback argument assigned to an event.
1371*/
1372EVENT2_EXPORT_SYMBOL
1373void *event_get_callback_arg(const struct event *ev);
1374
1375/**
1376 Return the priority of an event.
1377 @see event_priority_init(), event_get_priority()
1378*/
1379EVENT2_EXPORT_SYMBOL
1380int event_get_priority(const struct event *ev);
1381
1382/**
1383 Extract _all_ of arguments given to construct a given event. The
1384 event_base is copied into *base_out, the fd is copied into *fd_out, and so
1385 on.
1386
1387 If any of the "_out" arguments is NULL, it will be ignored.
1388 */
1389EVENT2_EXPORT_SYMBOL
1390void event_get_assignment(const struct event *event,
1391 struct event_base **base_out, evutil_socket_t *fd_out, short *events_out,
1392 event_callback_fn *callback_out, void **arg_out);
1393
1394/**
1395 Return the size of struct event that the Libevent library was compiled
1396 with.
1397
1398 This will be NO GREATER than sizeof(struct event) if you're running with
1399 the same version of Libevent that your application was built with, but
1400 otherwise might not.
1401
1402 Note that it might be SMALLER than sizeof(struct event) if some future
1403 version of Libevent adds extra padding to the end of struct event.
1404 We might do this to help ensure ABI-compatibility between different
1405 versions of Libevent.
1406 */
1407EVENT2_EXPORT_SYMBOL
1408size_t event_get_struct_event_size(void);
1409
1410/**
1411 Get the Libevent version.
1412
1413 Note that this will give you the version of the library that you're
1414 currently linked against, not the version of the headers that you've
1415 compiled against.
1416
1417 @return a string containing the version number of Libevent
1418*/
1419EVENT2_EXPORT_SYMBOL
1420const char *event_get_version(void);
1421
1422/**
1423 Return a numeric representation of Libevent's version.
1424
1425 Note that this will give you the version of the library that you're
1426 currently linked against, not the version of the headers you've used to
1427 compile.
1428
1429 The format uses one byte each for the major, minor, and patchlevel parts of
1430 the version number. The low-order byte is unused. For example, version
1431 2.0.1-alpha has a numeric representation of 0x02000100
1432*/
1433EVENT2_EXPORT_SYMBOL
1434ev_uint32_t event_get_version_number(void);
1435
1436/** As event_get_version, but gives the version of Libevent's headers. */
1437#define LIBEVENT_VERSION EVENT__VERSION
1438/** As event_get_version_number, but gives the version number of Libevent's
1439 * headers. */
1440#define LIBEVENT_VERSION_NUMBER EVENT__NUMERIC_VERSION
1441
1442/** Largest number of priorities that Libevent can support. */
1443#define EVENT_MAX_PRIORITIES 256
1444/**
1445 Set the number of different event priorities
1446
1447 By default Libevent schedules all active events with the same priority.
1448 However, some time it is desirable to process some events with a higher
1449 priority than others. For that reason, Libevent supports strict priority
1450 queues. Active events with a lower priority are always processed before
1451 events with a higher priority.
1452
1453 The number of different priorities can be set initially with the
1454 event_base_priority_init() function. This function should be called
1455 before the first call to event_base_dispatch(). The
1456 event_priority_set() function can be used to assign a priority to an
1457 event. By default, Libevent assigns the middle priority to all events
1458 unless their priority is explicitly set.
1459
1460 Note that urgent-priority events can starve less-urgent events: after
1461 running all urgent-priority callbacks, Libevent checks for more urgent
1462 events again, before running less-urgent events. Less-urgent events
1463 will not have their callbacks run until there are no events more urgent
1464 than them that want to be active.
1465
1466 @param eb the event_base structure returned by event_base_new()
1467 @param npriorities the maximum number of priorities
1468 @return 0 if successful, or -1 if an error occurred
1469 @see event_priority_set()
1470 */
1471EVENT2_EXPORT_SYMBOL
1472int event_base_priority_init(struct event_base *, int);
1473
1474/**
1475 Get the number of different event priorities.
1476
1477 @param eb the event_base structure returned by event_base_new()
1478 @return Number of different event priorities
1479 @see event_base_priority_init()
1480*/
1481EVENT2_EXPORT_SYMBOL
1482int event_base_get_npriorities(struct event_base *eb);
1483
1484/**
1485 Assign a priority to an event.
1486
1487 @param ev an event struct
1488 @param priority the new priority to be assigned
1489 @return 0 if successful, or -1 if an error occurred
1490 @see event_priority_init(), event_get_priority()
1491 */
1492EVENT2_EXPORT_SYMBOL
1493int event_priority_set(struct event *, int);
1494
1495/**
1496 Prepare an event_base to use a large number of timeouts with the same
1497 duration.
1498
1499 Libevent's default scheduling algorithm is optimized for having a large
1500 number of timeouts with their durations more or less randomly
1501 distributed. But if you have a large number of timeouts that all have
1502 the same duration (for example, if you have a large number of
1503 connections that all have a 10-second timeout), then you can improve
1504 Libevent's performance by telling Libevent about it.
1505
1506 To do this, call this function with the common duration. It will return a
1507 pointer to a different, opaque timeout value. (Don't depend on its actual
1508 contents!) When you use this timeout value in event_add(), Libevent will
1509 schedule the event more efficiently.
1510
1511 (This optimization probably will not be worthwhile until you have thousands
1512 or tens of thousands of events with the same timeout.)
1513 */
1514EVENT2_EXPORT_SYMBOL
1515const struct timeval *event_base_init_common_timeout(struct event_base *base,
1516 const struct timeval *duration);
1517
1518#if !defined(EVENT__DISABLE_MM_REPLACEMENT) || defined(EVENT_IN_DOXYGEN_)
1519/**
1520 Override the functions that Libevent uses for memory management.
1521
1522 Usually, Libevent uses the standard libc functions malloc, realloc, and
1523 free to allocate memory. Passing replacements for those functions to
1524 event_set_mem_functions() overrides this behavior.
1525
1526 Note that all memory returned from Libevent will be allocated by the
1527 replacement functions rather than by malloc() and realloc(). Thus, if you
1528 have replaced those functions, it will not be appropriate to free() memory
1529 that you get from Libevent. Instead, you must use the free_fn replacement
1530 that you provided.
1531
1532 Note also that if you are going to call this function, you should do so
1533 before any call to any Libevent function that does allocation.
1534 Otherwise, those funtions will allocate their memory using malloc(), but
1535 then later free it using your provided free_fn.
1536
1537 @param malloc_fn A replacement for malloc.
1538 @param realloc_fn A replacement for realloc
1539 @param free_fn A replacement for free.
1540 **/
1541EVENT2_EXPORT_SYMBOL
1542void event_set_mem_functions(
1543 void *(*malloc_fn)(size_t sz),
1544 void *(*realloc_fn)(void *ptr, size_t sz),
1545 void (*free_fn)(void *ptr));
1546/** This definition is present if Libevent was built with support for
1547 event_set_mem_functions() */
1548#define EVENT_SET_MEM_FUNCTIONS_IMPLEMENTED
1549#endif
1550
1551/**
1552 Writes a human-readable description of all inserted and/or active
1553 events to a provided stdio stream.
1554
1555 This is intended for debugging; its format is not guaranteed to be the same
1556 between libevent versions.
1557
1558 @param base An event_base on which to scan the events.
1559 @param output A stdio file to write on.
1560 */
1561EVENT2_EXPORT_SYMBOL
1562void event_base_dump_events(struct event_base *, FILE *);
1563
1564
1565/**
1566 Activates all pending events for the given fd and event mask.
1567
1568 This function activates pending events only. Events which have not been
1569 added will not become active.
1570
1571 @param base the event_base on which to activate the events.
1572 @param fd An fd to active events on.
1573 @param events One or more of EV_{READ,WRITE}.
1574 */
1575EVENT2_EXPORT_SYMBOL
1576void event_base_active_by_fd(struct event_base *base, evutil_socket_t fd, short events);
1577
1578/**
1579 Activates all pending signals with a given signal number
1580
1581 This function activates pending events only. Events which have not been
1582 added will not become active.
1583
1584 @param base the event_base on which to activate the events.
1585 @param fd The signal to active events on.
1586 */
1587EVENT2_EXPORT_SYMBOL
1588void event_base_active_by_signal(struct event_base *base, int sig);
1589
1590/**
1591 * Callback for iterating events in an event base via event_base_foreach_event
1592 */
1593typedef int (*event_base_foreach_event_cb)(const struct event_base *, const struct event *, void *);
1594
1595/**
1596 Iterate over all added or active events events in an event loop, and invoke
1597 a given callback on each one.
1598
1599 The callback must not call any function that modifies the event base, that
1600 modifies any event in the event base, or that adds or removes any event to
1601 the event base. Doing so is unsupported and will lead to undefined
1602 behavior -- likely, to crashes.
1603
1604 event_base_foreach_event() holds a lock on the event_base() for the whole
1605 time it's running: slow callbacks are not advisable.
1606
1607 Note that Libevent adds some events of its own to make pieces of its
1608 functionality work. You must not assume that the only events you'll
1609 encounter will be the ones you added yourself.
1610
1611 The callback function must return 0 to continue iteration, or some other
1612 integer to stop iterating.
1613
1614 @param base An event_base on which to scan the events.
1615 @param fn A callback function to receive the events.
1616 @param arg An argument passed to the callback function.
1617 @return 0 if we iterated over every event, or the value returned by the
1618 callback function if the loop exited early.
1619*/
1620EVENT2_EXPORT_SYMBOL
1621int event_base_foreach_event(struct event_base *base, event_base_foreach_event_cb fn, void *arg);
1622
1623
1624/** Sets 'tv' to the current time (as returned by gettimeofday()),
1625 looking at the cached value in 'base' if possible, and calling
1626 gettimeofday() or clock_gettime() as appropriate if there is no
1627 cached time.
1628
1629 Generally, this value will only be cached while actually
1630 processing event callbacks, and may be very inaccuate if your
1631 callbacks take a long time to execute.
1632
1633 Returns 0 on success, negative on failure.
1634 */
1635EVENT2_EXPORT_SYMBOL
1636int event_base_gettimeofday_cached(struct event_base *base,
1637 struct timeval *tv);
1638
1639/** Update cached_tv in the 'base' to the current time
1640 *
1641 * You can use this function is useful for selectively increasing
1642 * the accuracy of the cached time value in 'base' during callbacks
1643 * that take a long time to execute.
1644 *
1645 * This function has no effect if the base is currently not in its
1646 * event loop, or if timeval caching is disabled via
1647 * EVENT_BASE_FLAG_NO_CACHE_TIME.
1648 *
1649 * @return 0 on success, -1 on failure
1650 */
1651EVENT2_EXPORT_SYMBOL
1652int event_base_update_cache_time(struct event_base *base);
1653
1654/** Release up all globally-allocated resources allocated by Libevent.
1655
1656 This function does not free developer-controlled resources like
1657 event_bases, events, bufferevents, listeners, and so on. It only releases
1658 resources like global locks that there is no other way to free.
1659
1660 It is not actually necessary to call this function before exit: every
1661 resource that it frees would be released anyway on exit. It mainly exists
1662 so that resource-leak debugging tools don't see Libevent as holding
1663 resources at exit.
1664
1665 You should only call this function when no other Libevent functions will
1666 be invoked -- e.g., when cleanly exiting a program.
1667 */
1668EVENT2_EXPORT_SYMBOL
1669void libevent_global_shutdown(void);
1670
1671#ifdef __cplusplus
1672}
1673#endif
1674
1675#endif /* EVENT2_EVENT_H_INCLUDED_ */
1676