… | |
… | |
39 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
40 | support for multiple event loops, then all functions taking an initial |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
42 | will not have this argument. |
43 | |
43 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev 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 |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the double type in C. |
|
|
51 | |
|
|
52 | =head1 GLOBAL FUNCTIONS |
|
|
53 | |
|
|
54 | These functions can be called anytime, even before initialising the |
|
|
55 | library in any way. |
51 | |
56 | |
52 | =over 4 |
57 | =over 4 |
53 | |
58 | |
54 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
55 | |
60 | |
… | |
… | |
99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
104 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
105 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
106 | events, and dynamically created loops which do not. |
102 | |
107 | |
103 | If you use threads, a common model is to run the default event loop |
108 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
109 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
110 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
111 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
112 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
113 | done correctly, because it's hideous and inefficient). |
109 | |
114 | |
… | |
… | |
124 | |
129 | |
125 | It supports the following flags: |
130 | It supports the following flags: |
126 | |
131 | |
127 | =over 4 |
132 | =over 4 |
128 | |
133 | |
129 | =item EVFLAG_AUTO |
134 | =item C<EVFLAG_AUTO> |
130 | |
135 | |
131 | The default flags value. Use this if you have no clue (it's the right |
136 | The default flags value. Use this if you have no clue (it's the right |
132 | thing, believe me). |
137 | thing, believe me). |
133 | |
138 | |
134 | =item EVFLAG_NOENV |
139 | =item C<EVFLAG_NOENV> |
135 | |
140 | |
136 | If this flag bit is ored into the flag value (or the program runs setuid |
141 | If this flag bit is ored into the flag value (or the program runs setuid |
137 | or setgid) then libev will I<not> look at the environment variable |
142 | or setgid) then libev will I<not> look at the environment variable |
138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
143 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | override the flags completely if it is found in the environment. This is |
144 | override the flags completely if it is found in the environment. This is |
140 | useful to try out specific backends to test their performance, or to work |
145 | useful to try out specific backends to test their performance, or to work |
141 | around bugs. |
146 | around bugs. |
142 | |
147 | |
143 | =item EVMETHOD_SELECT (portable select backend) |
148 | =item C<EVMETHOD_SELECT> (portable select backend) |
144 | |
149 | |
145 | =item EVMETHOD_POLL (poll backend, available everywhere except on windows) |
150 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
146 | |
151 | |
147 | =item EVMETHOD_EPOLL (linux only) |
152 | =item C<EVMETHOD_EPOLL> (linux only) |
148 | |
153 | |
149 | =item EVMETHOD_KQUEUE (some bsds only) |
154 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
150 | |
155 | |
151 | =item EVMETHOD_DEVPOLL (solaris 8 only) |
156 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
152 | |
157 | |
153 | =item EVMETHOD_PORT (solaris 10 only) |
158 | =item C<EVMETHOD_PORT> (solaris 10 only) |
154 | |
159 | |
155 | If one or more of these are ored into the flags value, then only these |
160 | If one or more of these are ored into the flags value, then only these |
156 | backends will be tried (in the reverse order as given here). If one are |
161 | backends will be tried (in the reverse order as given here). If one are |
157 | specified, any backend will do. |
162 | specified, any backend will do. |
158 | |
163 | |
… | |
… | |
260 | |
265 | |
261 | =head1 ANATOMY OF A WATCHER |
266 | =head1 ANATOMY OF A WATCHER |
262 | |
267 | |
263 | A watcher is a structure that you create and register to record your |
268 | A watcher is a structure that you create and register to record your |
264 | interest in some event. For instance, if you want to wait for STDIN to |
269 | interest in some event. For instance, if you want to wait for STDIN to |
265 | become readable, you would create an ev_io watcher for that: |
270 | become readable, you would create an C<ev_io> watcher for that: |
266 | |
271 | |
267 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
272 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
268 | { |
273 | { |
269 | ev_io_stop (w); |
274 | ev_io_stop (w); |
270 | ev_unloop (loop, EVUNLOOP_ALL); |
275 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
299 | |
304 | |
300 | As long as your watcher is active (has been started but not stopped) you |
305 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
306 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
307 | reinitialise it or call its set method. |
303 | |
308 | |
304 | You cna check whether an event is active by calling the C<ev_is_active |
309 | You 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 |
310 | (watcher *)> macro. To see whether an event is outstanding (but the |
306 | callback for it has not been called yet) you cna use the C<ev_is_pending |
311 | callback for it has not been called yet) you can use the C<ev_is_pending |
307 | (watcher *)> macro. |
312 | (watcher *)> macro. |
308 | |
313 | |
309 | Each and every callback receives the event loop pointer as first, the |
314 | Each and every callback receives the event loop pointer as first, the |
310 | registered watcher structure as second, and a bitset of received events as |
315 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
316 | third argument. |
312 | |
317 | |
313 | The rceeived events usually include a single bit per event type received |
318 | The 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 |
319 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
320 | are: |
316 | |
321 | |
317 | =over 4 |
322 | =over 4 |
318 | |
323 | |
319 | =item EV_READ |
324 | =item C<EV_READ> |
320 | |
325 | |
321 | =item EV_WRITE |
326 | =item C<EV_WRITE> |
322 | |
327 | |
323 | The file descriptor in the ev_io watcher has become readable and/or |
328 | The file descriptor in the C<ev_io> watcher has become readable and/or |
324 | writable. |
329 | writable. |
325 | |
330 | |
326 | =item EV_TIMEOUT |
331 | =item C<EV_TIMEOUT> |
327 | |
332 | |
328 | The ev_timer watcher has timed out. |
333 | The C<ev_timer> watcher has timed out. |
329 | |
334 | |
330 | =item EV_PERIODIC |
335 | =item C<EV_PERIODIC> |
331 | |
336 | |
332 | The ev_periodic watcher has timed out. |
337 | The C<ev_periodic> watcher has timed out. |
333 | |
338 | |
334 | =item EV_SIGNAL |
339 | =item C<EV_SIGNAL> |
335 | |
340 | |
336 | The signal specified in the ev_signal watcher has been received by a thread. |
341 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
337 | |
342 | |
338 | =item EV_CHILD |
343 | =item C<EV_CHILD> |
339 | |
344 | |
340 | The pid specified in the ev_child watcher has received a status change. |
345 | The pid specified in the C<ev_child> watcher has received a status change. |
341 | |
346 | |
342 | =item EV_IDLE |
347 | =item C<EV_IDLE> |
343 | |
348 | |
344 | The ev_idle watcher has determined that you have nothing better to do. |
349 | The C<ev_idle> watcher has determined that you have nothing better to do. |
345 | |
350 | |
346 | =item EV_PREPARE |
351 | =item C<EV_PREPARE> |
347 | |
352 | |
348 | =item EV_CHECK |
353 | =item C<EV_CHECK> |
349 | |
354 | |
350 | All ev_prepare watchers are invoked just I<before> C<ev_loop> starts |
355 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
351 | to gather new events, and all ev_check watchers are invoked just after |
356 | to gather new events, and all C<ev_check> watchers are invoked just after |
352 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
357 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
353 | received events. Callbacks of both watcher types can start and stop as |
358 | received events. Callbacks of both watcher types can start and stop as |
354 | many watchers as they want, and all of them will be taken into account |
359 | many 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 |
360 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
356 | C<ev_loop> from blocking). |
361 | C<ev_loop> from blocking). |
357 | |
362 | |
358 | =item EV_ERROR |
363 | =item C<EV_ERROR> |
359 | |
364 | |
360 | An unspecified error has occured, the watcher has been stopped. This might |
365 | An unspecified error has occured, the watcher has been stopped. This might |
361 | happen because the watcher could not be properly started because libev |
366 | happen because the watcher could not be properly started because libev |
362 | ran out of memory, a file descriptor was found to be closed or any other |
367 | ran out of memory, a file descriptor was found to be closed or any other |
363 | problem. You best act on it by reporting the problem and somehow coping |
368 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
372 | =back |
377 | =back |
373 | |
378 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
379 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
380 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
381 | Each watcher has, by default, a member C<void *data> that you can change |
377 | and read at any time, libev will completely ignore it. This cna be used |
382 | and read at any time, libev will completely ignore it. This can be used |
378 | to associate arbitrary data with your watcher. If you need more data and |
383 | to associate arbitrary data with your watcher. If you need more data and |
379 | don't want to allocate memory and store a pointer to it in that data |
384 | don't want to allocate memory and store a pointer to it in that data |
380 | member, you can also "subclass" the watcher type and provide your own |
385 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
386 | data: |
382 | |
387 | |
… | |
… | |
404 | =head1 WATCHER TYPES |
409 | =head1 WATCHER TYPES |
405 | |
410 | |
406 | This section describes each watcher in detail, but will not repeat |
411 | This section describes each watcher in detail, but will not repeat |
407 | information given in the last section. |
412 | information given in the last section. |
408 | |
413 | |
409 | =head2 struct ev_io - is my file descriptor readable or writable |
414 | =head2 C<ev_io> - is this file descriptor readable or writable |
410 | |
415 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
416 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
417 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
418 | level-triggering because you keep receiving events as long as the |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
419 | condition persists. Remember you can stop the watcher if you don't want to |
415 | act on the event and neither want to receive future events). |
420 | act on the event and neither want to receive future events). |
416 | |
421 | |
417 | In general you can register as many read and/or write event watchers oer |
422 | In general you can register as many read and/or write event watchers per |
418 | fd as you want (as long as you don't confuse yourself). Setting all file |
423 | fd as you want (as long as you don't confuse yourself). Setting all file |
419 | descriptors to non-blocking mode is also usually a good idea (but not |
424 | descriptors to non-blocking mode is also usually a good idea (but not |
420 | required if you know what you are doing). |
425 | required if you know what you are doing). |
421 | |
426 | |
422 | You have to be careful with dup'ed file descriptors, though. Some backends |
427 | You have to be careful with dup'ed file descriptors, though. Some backends |
423 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
428 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
424 | descriptors correctly if you register interest in two or more fds pointing |
429 | descriptors correctly if you register interest in two or more fds pointing |
425 | to the same file/socket etc. description. |
430 | to the same file/socket etc. description (that is, they share the same |
|
|
431 | underlying "file open"). |
426 | |
432 | |
427 | If you must do this, then force the use of a known-to-be-good backend |
433 | If you must do this, then force the use of a known-to-be-good backend |
428 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
434 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
429 | EVMETHOD_POLL). |
435 | EVMETHOD_POLL). |
430 | |
436 | |
… | |
… | |
432 | |
438 | |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
439 | =item ev_io_init (ev_io *, callback, int fd, int events) |
434 | |
440 | |
435 | =item ev_io_set (ev_io *, int fd, int events) |
441 | =item ev_io_set (ev_io *, int fd, int events) |
436 | |
442 | |
437 | Configures an ev_io watcher. The fd is the file descriptor to rceeive |
443 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
444 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
439 | EV_WRITE> to receive the given events. |
445 | EV_WRITE> to receive the given events. |
440 | |
446 | |
441 | =back |
447 | =back |
442 | |
448 | |
443 | =head2 struct ev_timer - relative and optionally recurring timeouts |
449 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
444 | |
450 | |
445 | Timer watchers are simple relative timers that generate an event after a |
451 | Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that. |
452 | given time, and optionally repeating in regular intervals after that. |
447 | |
453 | |
448 | The timers are based on real time, that is, if you register an event that |
454 | The timers are based on real time, that is, if you register an event that |
449 | times out after an hour and youreset your system clock to last years |
455 | times out after an hour and you reset your system clock to last years |
450 | time, it will still time out after (roughly) and hour. "Roughly" because |
456 | time, it will still time out after (roughly) and hour. "Roughly" because |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
457 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
458 | monotonic clock option helps a lot here). |
453 | |
459 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
460 | The relative timeouts are calculated relative to the C<ev_now ()> |
455 | time. This is usually the right thing as this timestamp refers to the time |
461 | time. This is usually the right thing as this timestamp refers to the time |
456 | of the event triggering whatever timeout you are modifying/starting. If |
462 | of the event triggering whatever timeout you are modifying/starting. If |
457 | you suspect event processing to be delayed and you *need* to base the timeout |
463 | you suspect event processing to be delayed and you *need* to base the timeout |
458 | ion the current time, use something like this to adjust for this: |
464 | on the current time, use something like this to adjust for this: |
459 | |
465 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
466 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
461 | |
467 | |
462 | =over 4 |
468 | =over 4 |
463 | |
469 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
477 | later, again, and again, until stopped manually. |
472 | |
478 | |
473 | The timer itself will do a best-effort at avoiding drift, that is, if you |
479 | The timer itself will do a best-effort at avoiding drift, that is, if you |
474 | configure a timer to trigger every 10 seconds, then it will trigger at |
480 | configure a timer to trigger every 10 seconds, then it will trigger at |
475 | exactly 10 second intervals. If, however, your program cannot keep up with |
481 | exactly 10 second intervals. If, however, your program cannot keep up with |
476 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
482 | the timer (because it takes longer than those 10 seconds to do stuff) the |
477 | timer will not fire more than once per event loop iteration. |
483 | timer will not fire more than once per event loop iteration. |
478 | |
484 | |
479 | =item ev_timer_again (loop) |
485 | =item ev_timer_again (loop) |
480 | |
486 | |
481 | This will act as if the timer timed out and restart it again if it is |
487 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
488 | |
494 | |
489 | This sounds a bit complicated, but here is a useful and typical |
495 | This sounds a bit complicated, but here is a useful and typical |
490 | example: Imagine you have a tcp connection and you want a so-called idle |
496 | example: Imagine you have a tcp connection and you want a so-called idle |
491 | timeout, that is, you want to be called when there have been, say, 60 |
497 | timeout, that is, you want to be called when there have been, say, 60 |
492 | seconds of inactivity on the socket. The easiest way to do this is to |
498 | seconds of inactivity on the socket. The easiest way to do this is to |
493 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
499 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
494 | time you successfully read or write some data. If you go into an idle |
500 | time you successfully read or write some data. If you go into an idle |
495 | state where you do not expect data to travel on the socket, you can stop |
501 | state where you do not expect data to travel on the socket, you can stop |
496 | the timer, and again will automatically restart it if need be. |
502 | the timer, and again will automatically restart it if need be. |
497 | |
503 | |
498 | =back |
504 | =back |
499 | |
505 | |
500 | =head2 ev_periodic - to cron or not to cron it |
506 | =head2 C<ev_periodic> - to cron or not to cron |
501 | |
507 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
508 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
509 | (and unfortunately a bit complex). |
504 | |
510 | |
505 | Unlike ev_timer's, they are not based on real time (or relative time) |
511 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
506 | but on wallclock time (absolute time). You can tell a periodic watcher |
512 | but on wallclock time (absolute time). You can tell a periodic watcher |
507 | to trigger "at" some specific point in time. For example, if you tell a |
513 | to trigger "at" some specific point in time. For example, if you tell a |
508 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
514 | periodic 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 |
515 | + 10.>) and then reset your system clock to the last year, then it will |
510 | take a year to trigger the event (unlike an ev_timer, which would trigger |
516 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
511 | roughly 10 seconds later and of course not if you reset your system time |
517 | roughly 10 seconds later and of course not if you reset your system time |
512 | again). |
518 | again). |
513 | |
519 | |
514 | They can also be used to implement vastly more complex timers, such as |
520 | They can also be used to implement vastly more complex timers, such as |
515 | triggering an event on eahc midnight, local time. |
521 | triggering an event on eahc midnight, local time. |
… | |
… | |
544 | |
550 | |
545 | ev_periodic_set (&periodic, 0., 3600., 0); |
551 | ev_periodic_set (&periodic, 0., 3600., 0); |
546 | |
552 | |
547 | This doesn't mean there will always be 3600 seconds in between triggers, |
553 | This doesn't mean there will always be 3600 seconds in between triggers, |
548 | but only that the the callback will be called when the system time shows a |
554 | but only that the the callback will be called when the system time shows a |
549 | full hour (UTC), or more correct, when the system time is evenly divisible |
555 | full hour (UTC), or more correctly, when the system time is evenly divisible |
550 | by 3600. |
556 | by 3600. |
551 | |
557 | |
552 | Another way to think about it (for the mathematically inclined) is that |
558 | Another way to think about it (for the mathematically inclined) is that |
553 | ev_periodic will try to run the callback in this mode at the next possible |
559 | C<ev_periodic> will try to run the callback in this mode at the next possible |
554 | time where C<time = at (mod interval)>, regardless of any time jumps. |
560 | time where C<time = at (mod interval)>, regardless of any time jumps. |
555 | |
561 | |
556 | =item * manual reschedule mode (reschedule_cb = callback) |
562 | =item * manual reschedule mode (reschedule_cb = callback) |
557 | |
563 | |
558 | In this mode the values for C<interval> and C<at> are both being |
564 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
565 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
566 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
567 | current time as second argument. |
562 | |
568 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
569 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modificstions>. If you need |
570 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards. |
571 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
572 | starting a prepare watcher). |
566 | |
573 | |
567 | Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
574 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
568 | ev_tstamp now)>, e.g.: |
575 | ev_tstamp now)>, e.g.: |
569 | |
576 | |
570 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
577 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
571 | { |
578 | { |
572 | return now + 60.; |
579 | return now + 60.; |
… | |
… | |
575 | It must return the next time to trigger, based on the passed time value |
582 | It must return the next time to trigger, based on the passed time value |
576 | (that is, the lowest time value larger than to the second argument). It |
583 | (that is, the lowest time value larger than to the second argument). It |
577 | will usually be called just before the callback will be triggered, but |
584 | will usually be called just before the callback will be triggered, but |
578 | might be called at other times, too. |
585 | might be called at other times, too. |
579 | |
586 | |
|
|
587 | NOTE: I<< This callback must always return a time that is later than the |
|
|
588 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
589 | |
580 | This can be used to create very complex timers, such as a timer that |
590 | This can be used to create very complex timers, such as a timer that |
581 | triggers on each midnight, local time. To do this, you would calculate the |
591 | triggers on each midnight, local time. To do this, you would calculate the |
582 | next midnight after C<now> and return the timestamp value for this. How you do this |
592 | next midnight after C<now> and return the timestamp value for this. How |
583 | is, again, up to you (but it is not trivial). |
593 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
594 | reason I omitted it as an example). |
584 | |
595 | |
585 | =back |
596 | =back |
586 | |
597 | |
587 | =item ev_periodic_again (loop, ev_periodic *) |
598 | =item ev_periodic_again (loop, ev_periodic *) |
588 | |
599 | |
… | |
… | |
591 | a different time than the last time it was called (e.g. in a crond like |
602 | a different time than the last time it was called (e.g. in a crond like |
592 | program when the crontabs have changed). |
603 | program when the crontabs have changed). |
593 | |
604 | |
594 | =back |
605 | =back |
595 | |
606 | |
596 | =head2 ev_signal - signal me when a signal gets signalled |
607 | =head2 C<ev_signal> - signal me when a signal gets signalled |
597 | |
608 | |
598 | Signal watchers will trigger an event when the process receives a specific |
609 | Signal watchers will trigger an event when the process receives a specific |
599 | signal one or more times. Even though signals are very asynchronous, libev |
610 | signal one or more times. Even though signals are very asynchronous, libev |
600 | will try it's best to deliver signals synchronously, i.e. as part of the |
611 | will try it's best to deliver signals synchronously, i.e. as part of the |
601 | normal event processing, like any other event. |
612 | normal event processing, like any other event. |
602 | |
613 | |
603 | You cna configure as many watchers as you like per signal. Only when the |
614 | You can configure as many watchers as you like per signal. Only when the |
604 | first watcher gets started will libev actually register a signal watcher |
615 | first watcher gets started will libev actually register a signal watcher |
605 | with the kernel (thus it coexists with your own signal handlers as long |
616 | with the kernel (thus it coexists with your own signal handlers as long |
606 | as you don't register any with libev). Similarly, when the last signal |
617 | as you don't register any with libev). Similarly, when the last signal |
607 | watcher for a signal is stopped libev will reset the signal handler to |
618 | watcher for a signal is stopped libev will reset the signal handler to |
608 | SIG_DFL (regardless of what it was set to before). |
619 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
616 | Configures the watcher to trigger on the given signal number (usually one |
627 | Configures the watcher to trigger on the given signal number (usually one |
617 | of the C<SIGxxx> constants). |
628 | of the C<SIGxxx> constants). |
618 | |
629 | |
619 | =back |
630 | =back |
620 | |
631 | |
621 | =head2 ev_child - wait for pid status changes |
632 | =head2 C<ev_child> - wait for pid status changes |
622 | |
633 | |
623 | Child watchers trigger when your process receives a SIGCHLD in response to |
634 | Child watchers trigger when your process receives a SIGCHLD in response to |
624 | some child status changes (most typically when a child of yours dies). |
635 | some child status changes (most typically when a child of yours dies). |
625 | |
636 | |
626 | =over 4 |
637 | =over 4 |
… | |
… | |
630 | =item ev_child_set (ev_child *, int pid) |
641 | =item ev_child_set (ev_child *, int pid) |
631 | |
642 | |
632 | Configures the watcher to wait for status changes of process C<pid> (or |
643 | Configures the watcher to wait for status changes of process C<pid> (or |
633 | I<any> process if C<pid> is specified as C<0>). The callback can look |
644 | I<any> process if C<pid> is specified as C<0>). The callback can look |
634 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
645 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
635 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
646 | the status word (use the macros from C<sys/wait.h> and see your systems |
636 | contains the pid of the process causing the status change. |
647 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
648 | process causing the status change. |
637 | |
649 | |
638 | =back |
650 | =back |
639 | |
651 | |
640 | =head2 ev_idle - when you've got nothing better to do |
652 | =head2 C<ev_idle> - when you've got nothing better to do |
641 | |
653 | |
642 | Idle watchers trigger events when there are no other I/O or timer (or |
654 | Idle watchers trigger events when there are no other events are pending |
643 | periodic) events pending. That is, as long as your process is busy |
655 | (prepare, check and other idle watchers do not count). That is, as long |
644 | handling sockets or timeouts it will not be called. But when your process |
656 | as your process is busy handling sockets or timeouts (or even signals, |
645 | is idle all idle watchers are being called again and again - until |
657 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
658 | watchers are being called again and again, once per event loop iteration - |
646 | stopped, that is, or your process receives more events. |
659 | until stopped, that is, or your process receives more events and becomes |
|
|
660 | busy. |
647 | |
661 | |
648 | The most noteworthy effect is that as long as any idle watchers are |
662 | The most noteworthy effect is that as long as any idle watchers are |
649 | active, the process will not block when waiting for new events. |
663 | active, the process will not block when waiting for new events. |
650 | |
664 | |
651 | Apart from keeping your process non-blocking (which is a useful |
665 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
661 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
675 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
662 | believe me. |
676 | believe me. |
663 | |
677 | |
664 | =back |
678 | =back |
665 | |
679 | |
666 | =head2 prepare and check - your hooks into the event loop |
680 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
667 | |
681 | |
668 | Prepare and check watchers usually (but not always) are used in |
682 | Prepare and check watchers are usually (but not always) used in tandem: |
669 | tandom. Prepare watchers get invoked before the process blocks and check |
683 | prepare watchers get invoked before the process blocks and check watchers |
670 | watchers afterwards. |
684 | afterwards. |
671 | |
685 | |
672 | Their main purpose is to integrate other event mechanisms into libev. This |
686 | Their main purpose is to integrate other event mechanisms into libev. This |
673 | could be used, for example, to track variable changes, implement your own |
687 | could be used, for example, to track variable changes, implement your own |
674 | watchers, integrate net-snmp or a coroutine library and lots more. |
688 | watchers, integrate net-snmp or a coroutine library and lots more. |
675 | |
689 | |
676 | This is done by examining in each prepare call which file descriptors need |
690 | This is done by examining in each prepare call which file descriptors need |
677 | to be watched by the other library, registering ev_io watchers for them |
691 | to be watched by the other library, registering C<ev_io> watchers for |
678 | and starting an ev_timer watcher for any timeouts (many libraries provide |
692 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
679 | just this functionality). Then, in the check watcher you check for any |
693 | provide just this functionality). Then, in the check watcher you check for |
680 | events that occured (by making your callbacks set soem flags for example) |
694 | any events that occured (by checking the pending status of all watchers |
681 | and call back into the library. |
695 | and stopping them) and call back into the library. The I/O and timer |
|
|
696 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
697 | because you never know, you know?). |
682 | |
698 | |
683 | As another example, the perl Coro module uses these hooks to integrate |
699 | As another example, the Perl Coro module uses these hooks to integrate |
684 | coroutines into libev programs, by yielding to other active coroutines |
700 | coroutines into libev programs, by yielding to other active coroutines |
685 | during each prepare and only letting the process block if no coroutines |
701 | during each prepare and only letting the process block if no coroutines |
686 | are ready to run. |
702 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
703 | with priority higher than or equal to the event loop and one coroutine |
|
|
704 | of lower priority, but only once, using idle watchers to keep the event |
|
|
705 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
706 | low-priority coroutines to idle/background tasks). |
687 | |
707 | |
688 | =over 4 |
708 | =over 4 |
689 | |
709 | |
690 | =item ev_prepare_init (ev_prepare *, callback) |
710 | =item ev_prepare_init (ev_prepare *, callback) |
691 | |
711 | |
692 | =item ev_check_init (ev_check *, callback) |
712 | =item ev_check_init (ev_check *, callback) |
693 | |
713 | |
694 | Initialises and configures the prepare or check watcher - they have no |
714 | Initialises and configures the prepare or check watcher - they have no |
695 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
715 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
696 | macros, but using them is utterly, utterly pointless. |
716 | macros, but using them is utterly, utterly and completely pointless. |
697 | |
717 | |
698 | =back |
718 | =back |
699 | |
719 | |
700 | =head1 OTHER FUNCTIONS |
720 | =head1 OTHER FUNCTIONS |
701 | |
721 | |
702 | There are some other fucntions of possible interest. Described. Here. Now. |
722 | There are some other functions of possible interest. Described. Here. Now. |
703 | |
723 | |
704 | =over 4 |
724 | =over 4 |
705 | |
725 | |
706 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
726 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
707 | |
727 | |
708 | This function combines a simple timer and an I/O watcher, calls your |
728 | This function combines a simple timer and an I/O watcher, calls your |
709 | callback on whichever event happens first and automatically stop both |
729 | callback on whichever event happens first and automatically stop both |
710 | watchers. This is useful if you want to wait for a single event on an fd |
730 | watchers. This is useful if you want to wait for a single event on an fd |
711 | or timeout without havign to allocate/configure/start/stop/free one or |
731 | or timeout without having to allocate/configure/start/stop/free one or |
712 | more watchers yourself. |
732 | more watchers yourself. |
713 | |
733 | |
714 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
734 | If C<fd> is less than 0, then no I/O watcher will be started and events |
715 | ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set |
735 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
716 | will be craeted and started. |
736 | C<events> set will be craeted and started. |
717 | |
737 | |
718 | If C<timeout> is less than 0, then no timeout watcher will be |
738 | If C<timeout> is less than 0, then no timeout watcher will be |
719 | started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat |
739 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
720 | = 0) will be started. |
740 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
741 | dubious value. |
721 | |
742 | |
722 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
743 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
723 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
744 | passed an C<revents> set like normal event callbacks (a combination of |
724 | EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>: |
745 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
746 | value passed to C<ev_once>: |
725 | |
747 | |
726 | static void stdin_ready (int revents, void *arg) |
748 | static void stdin_ready (int revents, void *arg) |
727 | { |
749 | { |
728 | if (revents & EV_TIMEOUT) |
750 | if (revents & EV_TIMEOUT) |
729 | /* doh, nothing entered */ |
751 | /* doh, nothing entered */; |
730 | else if (revents & EV_READ) |
752 | else if (revents & EV_READ) |
731 | /* stdin might have data for us, joy! */ |
753 | /* stdin might have data for us, joy! */; |
732 | } |
754 | } |
733 | |
755 | |
734 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
756 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
735 | |
757 | |
736 | =item ev_feed_event (loop, watcher, int events) |
758 | =item ev_feed_event (loop, watcher, int events) |
737 | |
759 | |
738 | Feeds the given event set into the event loop, as if the specified event |
760 | Feeds the given event set into the event loop, as if the specified event |
739 | has happened for the specified watcher (which must be a pointer to an |
761 | had happened for the specified watcher (which must be a pointer to an |
740 | initialised but not necessarily active event watcher). |
762 | initialised but not necessarily started event watcher). |
741 | |
763 | |
742 | =item ev_feed_fd_event (loop, int fd, int revents) |
764 | =item ev_feed_fd_event (loop, int fd, int revents) |
743 | |
765 | |
744 | Feed an event on the given fd, as if a file descriptor backend detected it. |
766 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
767 | the given events it. |
745 | |
768 | |
746 | =item ev_feed_signal_event (loop, int signum) |
769 | =item ev_feed_signal_event (loop, int signum) |
747 | |
770 | |
748 | Feed an event as if the given signal occured (loop must be the default loop!). |
771 | Feed an event as if the given signal occured (loop must be the default loop!). |
749 | |
772 | |
750 | =back |
773 | =back |
751 | |
774 | |
|
|
775 | =head1 LIBEVENT EMULATION |
|
|
776 | |
|
|
777 | TBD. |
|
|
778 | |
|
|
779 | =head1 C++ SUPPORT |
|
|
780 | |
|
|
781 | TBD. |
|
|
782 | |
752 | =head1 AUTHOR |
783 | =head1 AUTHOR |
753 | |
784 | |
754 | Marc Lehmann <libev@schmorp.de>. |
785 | Marc Lehmann <libev@schmorp.de>. |
755 | |
786 | |