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39F<README.embed> in the libev distribution. If libev was configured without 39F<README.embed> in the libev distribution. If libev was configured without
40support for multiple event loops, then all functions taking an initial 40support for multiple event loops, then all functions taking an initial
41argument of name C<loop> (which is always of type C<struct ev_loop *>) 41argument of name C<loop> (which is always of type C<struct ev_loop *>)
42will not have this argument. 42will not have this argument.
43 43
44=head1 TIME AND OTHER GLOBAL FUNCTIONS 44=head1 TIME REPRESENTATION
45 45
46Libev represents time as a single floating point number, representing the 46Libev represents time as a single floating point number, representing the
47(fractional) number of seconds since the (POSIX) epoch (somewhere near 47(fractional) number of seconds since the (POSIX) epoch (somewhere near
48the beginning of 1970, details are complicated, don't ask). This type is 48the beginning of 1970, details are complicated, don't ask). This type is
49called C<ev_tstamp>, which is what you should use too. It usually aliases 49called C<ev_tstamp>, which is what you should use too. It usually aliases
50to the double type in C. 50to the double type in C.
51
52=head1 GLOBAL FUNCTIONS
51 53
52=over 4 54=over 4
53 55
54=item ev_tstamp ev_time () 56=item ev_tstamp ev_time ()
55 57
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99An event loop is described by a C<struct ev_loop *>. The library knows two 101An event loop is described by a C<struct ev_loop *>. The library knows two
100types of such loops, the I<default> loop, which supports signals and child 102types of such loops, the I<default> loop, which supports signals and child
101events, and dynamically created loops which do not. 103events, and dynamically created loops which do not.
102 104
103If you use threads, a common model is to run the default event loop 105If you use threads, a common model is to run the default event loop
104in your main thread (or in a separate thrad) and for each thread you 106in your main thread (or in a separate thread) and for each thread you
105create, you also create another event loop. Libev itself does no locking 107create, you also create another event loop. Libev itself does no locking
106whatsoever, so if you mix calls to the same event loop in different 108whatsoever, so if you mix calls to the same event loop in different
107threads, make sure you lock (this is usually a bad idea, though, even if 109threads, make sure you lock (this is usually a bad idea, though, even if
108done correctly, because it's hideous and inefficient). 110done correctly, because it's hideous and inefficient).
109 111
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124 126
125It supports the following flags: 127It supports the following flags:
126 128
127=over 4 129=over 4
128 130
129=item EVFLAG_AUTO 131=item C<EVFLAG_AUTO>
130 132
131The default flags value. Use this if you have no clue (it's the right 133The default flags value. Use this if you have no clue (it's the right
132thing, believe me). 134thing, believe me).
133 135
134=item EVFLAG_NOENV 136=item C<EVFLAG_NOENV>
135 137
136If this flag bit is ored into the flag value (or the program runs setuid 138If this flag bit is ored into the flag value (or the program runs setuid
137or setgid) then libev will I<not> look at the environment variable 139or setgid) then libev will I<not> look at the environment variable
138C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will 140C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
139override the flags completely if it is found in the environment. This is 141override the flags completely if it is found in the environment. This is
140useful to try out specific backends to test their performance, or to work 142useful to try out specific backends to test their performance, or to work
141around bugs. 143around bugs.
142 144
143=item EVMETHOD_SELECT (portable select backend) 145=item C<EVMETHOD_SELECT> (portable select backend)
144 146
145=item EVMETHOD_POLL (poll backend, available everywhere except on windows) 147=item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows)
146 148
147=item EVMETHOD_EPOLL (linux only) 149=item C<EVMETHOD_EPOLL> (linux only)
148 150
149=item EVMETHOD_KQUEUE (some bsds only) 151=item C<EVMETHOD_KQUEUE> (some bsds only)
150 152
151=item EVMETHOD_DEVPOLL (solaris 8 only) 153=item C<EVMETHOD_DEVPOLL> (solaris 8 only)
152 154
153=item EVMETHOD_PORT (solaris 10 only) 155=item C<EVMETHOD_PORT> (solaris 10 only)
154 156
155If one or more of these are ored into the flags value, then only these 157If one or more of these are ored into the flags value, then only these
156backends will be tried (in the reverse order as given here). If one are 158backends will be tried (in the reverse order as given here). If one are
157specified, any backend will do. 159specified, any backend will do.
158 160
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260 262
261=head1 ANATOMY OF A WATCHER 263=head1 ANATOMY OF A WATCHER
262 264
263A watcher is a structure that you create and register to record your 265A watcher is a structure that you create and register to record your
264interest in some event. For instance, if you want to wait for STDIN to 266interest in some event. For instance, if you want to wait for STDIN to
265become readable, you would create an ev_io watcher for that: 267become readable, you would create an C<ev_io> watcher for that:
266 268
267 static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 269 static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
268 { 270 {
269 ev_io_stop (w); 271 ev_io_stop (w);
270 ev_unloop (loop, EVUNLOOP_ALL); 272 ev_unloop (loop, EVUNLOOP_ALL);
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299 301
300As long as your watcher is active (has been started but not stopped) you 302As long as your watcher is active (has been started but not stopped) you
301must not touch the values stored in it. Most specifically you must never 303must not touch the values stored in it. Most specifically you must never
302reinitialise it or call its set method. 304reinitialise it or call its set method.
303 305
304You cna check whether an event is active by calling the C<ev_is_active 306You can check whether an event is active by calling the C<ev_is_active
305(watcher *)> macro. To see whether an event is outstanding (but the 307(watcher *)> macro. To see whether an event is outstanding (but the
306callback for it has not been called yet) you cna use the C<ev_is_pending 308callback for it has not been called yet) you can use the C<ev_is_pending
307(watcher *)> macro. 309(watcher *)> macro.
308 310
309Each and every callback receives the event loop pointer as first, the 311Each and every callback receives the event loop pointer as first, the
310registered watcher structure as second, and a bitset of received events as 312registered watcher structure as second, and a bitset of received events as
311third argument. 313third argument.
312 314
313The rceeived events usually include a single bit per event type received 315The received events usually include a single bit per event type received
314(you can receive multiple events at the same time). The possible bit masks 316(you can receive multiple events at the same time). The possible bit masks
315are: 317are:
316 318
317=over 4 319=over 4
318 320
319=item EV_READ 321=item C<EV_READ>
320 322
321=item EV_WRITE 323=item C<EV_WRITE>
322 324
323The file descriptor in the ev_io watcher has become readable and/or 325The file descriptor in the C<ev_io> watcher has become readable and/or
324writable. 326writable.
325 327
326=item EV_TIMEOUT 328=item C<EV_TIMEOUT>
327 329
328The ev_timer watcher has timed out. 330The C<ev_timer> watcher has timed out.
329 331
330=item EV_PERIODIC 332=item C<EV_PERIODIC>
331 333
332The ev_periodic watcher has timed out. 334The C<ev_periodic> watcher has timed out.
333 335
334=item EV_SIGNAL 336=item C<EV_SIGNAL>
335 337
336The signal specified in the ev_signal watcher has been received by a thread. 338The signal specified in the C<ev_signal> watcher has been received by a thread.
337 339
338=item EV_CHILD 340=item C<EV_CHILD>
339 341
340The pid specified in the ev_child watcher has received a status change. 342The pid specified in the C<ev_child> watcher has received a status change.
341 343
342=item EV_IDLE 344=item C<EV_IDLE>
343 345
344The ev_idle watcher has determined that you have nothing better to do. 346The C<ev_idle> watcher has determined that you have nothing better to do.
345 347
346=item EV_PREPARE 348=item C<EV_PREPARE>
347 349
348=item EV_CHECK 350=item C<EV_CHECK>
349 351
350All ev_prepare watchers are invoked just I<before> C<ev_loop> starts 352All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts
351to gather new events, and all ev_check watchers are invoked just after 353to gather new events, and all C<ev_check> watchers are invoked just after
352C<ev_loop> has gathered them, but before it invokes any callbacks for any 354C<ev_loop> has gathered them, but before it invokes any callbacks for any
353received events. Callbacks of both watcher types can start and stop as 355received events. Callbacks of both watcher types can start and stop as
354many watchers as they want, and all of them will be taken into account 356many watchers as they want, and all of them will be taken into account
355(for example, a ev_prepare watcher might start an idle watcher to keep 357(for example, a C<ev_prepare> watcher might start an idle watcher to keep
356C<ev_loop> from blocking). 358C<ev_loop> from blocking).
357 359
358=item EV_ERROR 360=item C<EV_ERROR>
359 361
360An unspecified error has occured, the watcher has been stopped. This might 362An unspecified error has occured, the watcher has been stopped. This might
361happen because the watcher could not be properly started because libev 363happen because the watcher could not be properly started because libev
362ran out of memory, a file descriptor was found to be closed or any other 364ran out of memory, a file descriptor was found to be closed or any other
363problem. You best act on it by reporting the problem and somehow coping 365problem. You best act on it by reporting the problem and somehow coping
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372=back 374=back
373 375
374=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER 376=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
375 377
376Each watcher has, by default, a member C<void *data> that you can change 378Each watcher has, by default, a member C<void *data> that you can change
377and read at any time, libev will completely ignore it. This cna be used 379and read at any time, libev will completely ignore it. This can be used
378to associate arbitrary data with your watcher. If you need more data and 380to associate arbitrary data with your watcher. If you need more data and
379don't want to allocate memory and store a pointer to it in that data 381don't want to allocate memory and store a pointer to it in that data
380member, you can also "subclass" the watcher type and provide your own 382member, you can also "subclass" the watcher type and provide your own
381data: 383data:
382 384
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404=head1 WATCHER TYPES 406=head1 WATCHER TYPES
405 407
406This section describes each watcher in detail, but will not repeat 408This section describes each watcher in detail, but will not repeat
407information given in the last section. 409information given in the last section.
408 410
409=head2 struct ev_io - is my file descriptor readable or writable 411=head2 C<ev_io> - is this file descriptor readable or writable
410 412
411I/O watchers check whether a file descriptor is readable or writable 413I/O watchers check whether a file descriptor is readable or writable
412in each iteration of the event loop (This behaviour is called 414in each iteration of the event loop (This behaviour is called
413level-triggering because you keep receiving events as long as the 415level-triggering because you keep receiving events as long as the
414condition persists. Remember you cna stop the watcher if you don't want to 416condition persists. Remember you can stop the watcher if you don't want to
415act on the event and neither want to receive future events). 417act on the event and neither want to receive future events).
416 418
417In general you can register as many read and/or write event watchers oer 419In general you can register as many read and/or write event watchers oer
418fd as you want (as long as you don't confuse yourself). Setting all file 420fd as you want (as long as you don't confuse yourself). Setting all file
419descriptors to non-blocking mode is also usually a good idea (but not 421descriptors to non-blocking mode is also usually a good idea (but not
… …
432 434
433=item ev_io_init (ev_io *, callback, int fd, int events) 435=item ev_io_init (ev_io *, callback, int fd, int events)
434 436
435=item ev_io_set (ev_io *, int fd, int events) 437=item ev_io_set (ev_io *, int fd, int events)
436 438
437Configures an ev_io watcher. The fd is the file descriptor to rceeive 439Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive
438events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | 440events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ |
439EV_WRITE> to receive the given events. 441EV_WRITE> to receive the given events.
440 442
441=back 443=back
442 444
443=head2 struct ev_timer - relative and optionally recurring timeouts 445=head2 C<ev_timer> - relative and optionally recurring timeouts
444 446
445Timer watchers are simple relative timers that generate an event after a 447Timer watchers are simple relative timers that generate an event after a
446given time, and optionally repeating in regular intervals after that. 448given time, and optionally repeating in regular intervals after that.
447 449
448The timers are based on real time, that is, if you register an event that 450The timers are based on real time, that is, if you register an event that
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488 490
489This sounds a bit complicated, but here is a useful and typical 491This sounds a bit complicated, but here is a useful and typical
490example: Imagine you have a tcp connection and you want a so-called idle 492example: Imagine you have a tcp connection and you want a so-called idle
491timeout, that is, you want to be called when there have been, say, 60 493timeout, that is, you want to be called when there have been, say, 60
492seconds of inactivity on the socket. The easiest way to do this is to 494seconds of inactivity on the socket. The easiest way to do this is to
493configure an ev_timer with after=repeat=60 and calling ev_timer_again each 495configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each
494time you successfully read or write some data. If you go into an idle 496time you successfully read or write some data. If you go into an idle
495state where you do not expect data to travel on the socket, you can stop 497state where you do not expect data to travel on the socket, you can stop
496the timer, and again will automatically restart it if need be. 498the timer, and again will automatically restart it if need be.
497 499
498=back 500=back
499 501
500=head2 ev_periodic - to cron or not to cron it 502=head2 C<ev_periodic> - to cron or not to cron
501 503
502Periodic watchers are also timers of a kind, but they are very versatile 504Periodic watchers are also timers of a kind, but they are very versatile
503(and unfortunately a bit complex). 505(and unfortunately a bit complex).
504 506
505Unlike ev_timer's, they are not based on real time (or relative time) 507Unlike C<ev_timer>'s, they are not based on real time (or relative time)
506but on wallclock time (absolute time). You can tell a periodic watcher 508but on wallclock time (absolute time). You can tell a periodic watcher
507to trigger "at" some specific point in time. For example, if you tell a 509to trigger "at" some specific point in time. For example, if you tell a
508periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () 510periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()
509+ 10.>) and then reset your system clock to the last year, then it will 511+ 10.>) and then reset your system clock to the last year, then it will
510take a year to trigger the event (unlike an ev_timer, which would trigger 512take a year to trigger the event (unlike an C<ev_timer>, which would trigger
511roughly 10 seconds later and of course not if you reset your system time 513roughly 10 seconds later and of course not if you reset your system time
512again). 514again).
513 515
514They can also be used to implement vastly more complex timers, such as 516They can also be used to implement vastly more complex timers, such as
515triggering an event on eahc midnight, local time. 517triggering an event on eahc midnight, local time.
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544 546
545 ev_periodic_set (&periodic, 0., 3600., 0); 547 ev_periodic_set (&periodic, 0., 3600., 0);
546 548
547This doesn't mean there will always be 3600 seconds in between triggers, 549This doesn't mean there will always be 3600 seconds in between triggers,
548but only that the the callback will be called when the system time shows a 550but only that the the callback will be called when the system time shows a
549full hour (UTC), or more correct, when the system time is evenly divisible 551full hour (UTC), or more correctly, when the system time is evenly divisible
550by 3600. 552by 3600.
551 553
552Another way to think about it (for the mathematically inclined) is that 554Another way to think about it (for the mathematically inclined) is that
553ev_periodic will try to run the callback in this mode at the next possible 555C<ev_periodic> will try to run the callback in this mode at the next possible
554time where C<time = at (mod interval)>, regardless of any time jumps. 556time where C<time = at (mod interval)>, regardless of any time jumps.
555 557
556=item * manual reschedule mode (reschedule_cb = callback) 558=item * manual reschedule mode (reschedule_cb = callback)
557 559
558In this mode the values for C<interval> and C<at> are both being 560In this mode the values for C<interval> and C<at> are both being
559ignored. Instead, each time the periodic watcher gets scheduled, the 561ignored. Instead, each time the periodic watcher gets scheduled, the
560reschedule callback will be called with the watcher as first, and the 562reschedule callback will be called with the watcher as first, and the
561current time as second argument. 563current time as second argument.
562 564
563NOTE: I<This callback MUST NOT stop or destroy the periodic or any other 565NOTE: I<This callback MUST NOT stop or destroy the periodic or any other
564periodic watcher, ever, or make any event loop modificstions>. If you need 566periodic watcher, ever, or make any event loop modifications>. If you need
565to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards. 567to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards.
566 568
569Also, I<< this callback must always return a time that is later than the
570passed C<now> value >>. Not even C<now> itself will be ok.
571
567Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 572Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
568ev_tstamp now)>, e.g.: 573ev_tstamp now)>, e.g.:
569 574
570 static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) 575 static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
571 { 576 {
572 return now + 60.; 577 return now + 60.;
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591a different time than the last time it was called (e.g. in a crond like 596a different time than the last time it was called (e.g. in a crond like
592program when the crontabs have changed). 597program when the crontabs have changed).
593 598
594=back 599=back
595 600
596=head2 ev_signal - signal me when a signal gets signalled 601=head2 C<ev_signal> - signal me when a signal gets signalled
597 602
598Signal watchers will trigger an event when the process receives a specific 603Signal watchers will trigger an event when the process receives a specific
599signal one or more times. Even though signals are very asynchronous, libev 604signal one or more times. Even though signals are very asynchronous, libev
600will try it's best to deliver signals synchronously, i.e. as part of the 605will try it's best to deliver signals synchronously, i.e. as part of the
601normal event processing, like any other event. 606normal event processing, like any other event.
602 607
603You cna configure as many watchers as you like per signal. Only when the 608You can configure as many watchers as you like per signal. Only when the
604first watcher gets started will libev actually register a signal watcher 609first watcher gets started will libev actually register a signal watcher
605with the kernel (thus it coexists with your own signal handlers as long 610with the kernel (thus it coexists with your own signal handlers as long
606as you don't register any with libev). Similarly, when the last signal 611as you don't register any with libev). Similarly, when the last signal
607watcher for a signal is stopped libev will reset the signal handler to 612watcher for a signal is stopped libev will reset the signal handler to
608SIG_DFL (regardless of what it was set to before). 613SIG_DFL (regardless of what it was set to before).
… …
616Configures the watcher to trigger on the given signal number (usually one 621Configures the watcher to trigger on the given signal number (usually one
617of the C<SIGxxx> constants). 622of the C<SIGxxx> constants).
618 623
619=back 624=back
620 625
621=head2 ev_child - wait for pid status changes 626=head2 C<ev_child> - wait for pid status changes
622 627
623Child watchers trigger when your process receives a SIGCHLD in response to 628Child watchers trigger when your process receives a SIGCHLD in response to
624some child status changes (most typically when a child of yours dies). 629some child status changes (most typically when a child of yours dies).
625 630
626=over 4 631=over 4
… …
630=item ev_child_set (ev_child *, int pid) 635=item ev_child_set (ev_child *, int pid)
631 636
632Configures the watcher to wait for status changes of process C<pid> (or 637Configures the watcher to wait for status changes of process C<pid> (or
633I<any> process if C<pid> is specified as C<0>). The callback can look 638I<any> process if C<pid> is specified as C<0>). The callback can look
634at the C<rstatus> member of the C<ev_child> watcher structure to see 639at the C<rstatus> member of the C<ev_child> watcher structure to see
635the status word (use the macros from C<sys/wait.h>). The C<rpid> member 640the status word (use the macros from C<sys/wait.h> and see your systems
636contains the pid of the process causing the status change. 641C<waitpid> documentation). The C<rpid> member contains the pid of the
642process causing the status change.
637 643
638=back 644=back
639 645
640=head2 ev_idle - when you've got nothing better to do 646=head2 C<ev_idle> - when you've got nothing better to do
641 647
642Idle watchers trigger events when there are no other I/O or timer (or 648Idle watchers trigger events when there are no other events are pending
643periodic) events pending. That is, as long as your process is busy 649(prepare, check and other idle watchers do not count). That is, as long
644handling sockets or timeouts it will not be called. But when your process 650as your process is busy handling sockets or timeouts (or even signals,
645is idle all idle watchers are being called again and again - until 651imagine) it will not be triggered. But when your process is idle all idle
652watchers are being called again and again, once per event loop iteration -
646stopped, that is, or your process receives more events. 653until stopped, that is, or your process receives more events and becomes
654busy.
647 655
648The most noteworthy effect is that as long as any idle watchers are 656The most noteworthy effect is that as long as any idle watchers are
649active, the process will not block when waiting for new events. 657active, the process will not block when waiting for new events.
650 658
651Apart from keeping your process non-blocking (which is a useful 659Apart from keeping your process non-blocking (which is a useful
… …
661kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, 669kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
662believe me. 670believe me.
663 671
664=back 672=back
665 673
666=head2 prepare and check - your hooks into the event loop 674=head2 C<ev_prepare> and C<ev_check> - customise your event loop
667 675
668Prepare and check watchers usually (but not always) are used in 676Prepare and check watchers are usually (but not always) used in tandem:
669tandom. Prepare watchers get invoked before the process blocks and check 677Prepare watchers get invoked before the process blocks and check watchers
670watchers afterwards. 678afterwards.
671 679
672Their main purpose is to integrate other event mechanisms into libev. This 680Their main purpose is to integrate other event mechanisms into libev. This
673could be used, for example, to track variable changes, implement your own 681could be used, for example, to track variable changes, implement your own
674watchers, integrate net-snmp or a coroutine library and lots more. 682watchers, integrate net-snmp or a coroutine library and lots more.
675 683
676This is done by examining in each prepare call which file descriptors need 684This is done by examining in each prepare call which file descriptors need
677to be watched by the other library, registering ev_io watchers for them 685to be watched by the other library, registering C<ev_io> watchers for
678and starting an ev_timer watcher for any timeouts (many libraries provide 686them and starting an C<ev_timer> watcher for any timeouts (many libraries
679just this functionality). Then, in the check watcher you check for any 687provide just this functionality). Then, in the check watcher you check for
680events that occured (by making your callbacks set soem flags for example) 688any events that occured (by checking the pending status of all watchers
681and call back into the library. 689and stopping them) and call back into the library. The I/O and timer
690callbacks will never actually be called (but must be valid neverthelles,
691because you never know, you know?).
682 692
683As another example, the perl Coro module uses these hooks to integrate 693As another example, the Perl Coro module uses these hooks to integrate
684coroutines into libev programs, by yielding to other active coroutines 694coroutines into libev programs, by yielding to other active coroutines
685during each prepare and only letting the process block if no coroutines 695during each prepare and only letting the process block if no coroutines
686are ready to run. 696are ready to run (its actually more complicated, it only runs coroutines
697with priority higher than the event loop and one lower priority once,
698using idle watchers to keep the event loop from blocking if lower-priority
699coroutines exist, thus mapping low-priority coroutines to idle/background
700tasks).
687 701
688=over 4 702=over 4
689 703
690=item ev_prepare_init (ev_prepare *, callback) 704=item ev_prepare_init (ev_prepare *, callback)
691 705
692=item ev_check_init (ev_check *, callback) 706=item ev_check_init (ev_check *, callback)
693 707
694Initialises and configures the prepare or check watcher - they have no 708Initialises and configures the prepare or check watcher - they have no
695parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> 709parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
696macros, but using them is utterly, utterly pointless. 710macros, but using them is utterly, utterly and completely pointless.
697 711
698=back 712=back
699 713
700=head1 OTHER FUNCTIONS 714=head1 OTHER FUNCTIONS
701 715
702There are some other fucntions of possible interest. Described. Here. Now. 716There are some other functions of possible interest. Described. Here. Now.
703 717
704=over 4 718=over 4
705 719
706=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) 720=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
707 721
… …
709callback on whichever event happens first and automatically stop both 723callback on whichever event happens first and automatically stop both
710watchers. This is useful if you want to wait for a single event on an fd 724watchers. This is useful if you want to wait for a single event on an fd
711or timeout without havign to allocate/configure/start/stop/free one or 725or timeout without havign to allocate/configure/start/stop/free one or
712more watchers yourself. 726more watchers yourself.
713 727
714If C<fd> is less than 0, then no I/O watcher will be started and events is 728If C<fd> is less than 0, then no I/O watcher will be started and events
715ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set 729is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
716will be craeted and started. 730C<events> set will be craeted and started.
717 731
718If C<timeout> is less than 0, then no timeout watcher will be 732If C<timeout> is less than 0, then no timeout watcher will be
719started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat 733started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
720= 0) will be started. 734repeat = 0) will be started. While C<0> is a valid timeout, it is of
735dubious value.
721 736
722The callback has the type C<void (*cb)(int revents, void *arg)> and 737The callback has the type C<void (*cb)(int revents, void *arg)> and gets
723gets passed an events set (normally a combination of EV_ERROR, EV_READ, 738passed an events set like normal event callbacks (with a combination of
724EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>: 739C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
740value passed to C<ev_once>:
725 741
726 static void stdin_ready (int revents, void *arg) 742 static void stdin_ready (int revents, void *arg)
727 { 743 {
728 if (revents & EV_TIMEOUT) 744 if (revents & EV_TIMEOUT)
729 /* doh, nothing entered */ 745 /* doh, nothing entered */;
730 else if (revents & EV_READ) 746 else if (revents & EV_READ)
731 /* stdin might have data for us, joy! */ 747 /* stdin might have data for us, joy! */;
732 } 748 }
733 749
734 ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); 750 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
735 751
736=item ev_feed_event (loop, watcher, int events) 752=item ev_feed_event (loop, watcher, int events)
737 753
738Feeds the given event set into the event loop, as if the specified event 754Feeds the given event set into the event loop, as if the specified event
739has happened for the specified watcher (which must be a pointer to an 755had happened for the specified watcher (which must be a pointer to an
740initialised but not necessarily active event watcher). 756initialised but not necessarily started event watcher).
741 757
742=item ev_feed_fd_event (loop, int fd, int revents) 758=item ev_feed_fd_event (loop, int fd, int revents)
743 759
744Feed an event on the given fd, as if a file descriptor backend detected it. 760Feed an event on the given fd, as if a file descriptor backend detected
761the given events it.
745 762
746=item ev_feed_signal_event (loop, int signum) 763=item ev_feed_signal_event (loop, int signum)
747 764
748Feed an event as if the given signal occured (loop must be the default loop!). 765Feed an event as if the given signal occured (loop must be the default loop!).
749 766

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