… | |
… | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
13 | |
13 | |
|
|
14 | #include <stdio.h> // for puts |
|
|
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_<type> |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
18 | |
20 | |
19 | // all watcher callbacks have a similar signature |
21 | // all watcher callbacks have a similar signature |
20 | // this callback is called when data is readable on stdin |
22 | // this callback is called when data is readable on stdin |
21 | static void |
23 | static void |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
24 | stdin_cb (EV_P_ ev_io *w, int revents) |
23 | { |
25 | { |
24 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
25 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
26 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
27 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
… | |
… | |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
31 | } |
33 | } |
32 | |
34 | |
33 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
34 | static void |
36 | static void |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
36 | { |
38 | { |
37 | puts ("timeout"); |
39 | puts ("timeout"); |
38 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_loop to stop iterating |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
40 | } |
42 | } |
… | |
… | |
103 | Libev is very configurable. In this manual the default (and most common) |
105 | Libev is very configurable. In this manual the default (and most common) |
104 | configuration will be described, which supports multiple event loops. For |
106 | configuration will be described, which supports multiple event loops. For |
105 | more info about various configuration options please have a look at |
107 | more info about various configuration options please have a look at |
106 | B<EMBED> section in this manual. If libev was configured without support |
108 | B<EMBED> section in this manual. If libev was configured without support |
107 | for multiple event loops, then all functions taking an initial argument of |
109 | for multiple event loops, then all functions taking an initial argument of |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
110 | name C<loop> (which is always of type C<ev_loop *>) will not have |
109 | this argument. |
111 | this argument. |
110 | |
112 | |
111 | =head2 TIME REPRESENTATION |
113 | =head2 TIME REPRESENTATION |
112 | |
114 | |
113 | Libev represents time as a single floating point number, representing the |
115 | Libev represents time as a single floating point number, representing the |
… | |
… | |
276 | |
278 | |
277 | =back |
279 | =back |
278 | |
280 | |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
281 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
280 | |
282 | |
281 | An event loop is described by a C<struct ev_loop *>. The library knows two |
283 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
282 | types of such loops, the I<default> loop, which supports signals and child |
284 | is I<not> optional in this case, as there is also an C<ev_loop> |
283 | events, and dynamically created loops which do not. |
285 | I<function>). |
|
|
286 | |
|
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287 | The library knows two types of such loops, the I<default> loop, which |
|
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288 | supports signals and child events, and dynamically created loops which do |
|
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289 | not. |
284 | |
290 | |
285 | =over 4 |
291 | =over 4 |
286 | |
292 | |
287 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
293 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
288 | |
294 | |
… | |
… | |
294 | If you don't know what event loop to use, use the one returned from this |
300 | If you don't know what event loop to use, use the one returned from this |
295 | function. |
301 | function. |
296 | |
302 | |
297 | Note that this function is I<not> thread-safe, so if you want to use it |
303 | Note that this function is I<not> thread-safe, so if you want to use it |
298 | from multiple threads, you have to lock (note also that this is unlikely, |
304 | from multiple threads, you have to lock (note also that this is unlikely, |
299 | as loops cannot bes hared easily between threads anyway). |
305 | as loops cannot be shared easily between threads anyway). |
300 | |
306 | |
301 | The default loop is the only loop that can handle C<ev_signal> and |
307 | The default loop is the only loop that can handle C<ev_signal> and |
302 | C<ev_child> watchers, and to do this, it always registers a handler |
308 | C<ev_child> watchers, and to do this, it always registers a handler |
303 | for C<SIGCHLD>. If this is a problem for your application you can either |
309 | for C<SIGCHLD>. If this is a problem for your application you can either |
304 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
310 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
… | |
… | |
380 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
386 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
381 | |
387 | |
382 | For few fds, this backend is a bit little slower than poll and select, |
388 | For few fds, this backend is a bit little slower than poll and select, |
383 | but it scales phenomenally better. While poll and select usually scale |
389 | but it scales phenomenally better. While poll and select usually scale |
384 | like O(total_fds) where n is the total number of fds (or the highest fd), |
390 | like O(total_fds) where n is the total number of fds (or the highest fd), |
385 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
391 | epoll scales either O(1) or O(active_fds). |
386 | of shortcomings, such as silently dropping events in some hard-to-detect |
392 | |
387 | cases and requiring a system call per fd change, no fork support and bad |
393 | The epoll mechanism deserves honorable mention as the most misdesigned |
388 | support for dup. |
394 | of the more advanced event mechanisms: mere annoyances include silently |
|
|
395 | dropping file descriptors, requiring a system call per change per file |
|
|
396 | descriptor (and unnecessary guessing of parameters), problems with dup and |
|
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397 | so on. The biggest issue is fork races, however - if a program forks then |
|
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398 | I<both> parent and child process have to recreate the epoll set, which can |
|
|
399 | take considerable time (one syscall per file descriptor) and is of course |
|
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400 | hard to detect. |
|
|
401 | |
|
|
402 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
|
|
403 | of course I<doesn't>, and epoll just loves to report events for totally |
|
|
404 | I<different> file descriptors (even already closed ones, so one cannot |
|
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405 | even remove them from the set) than registered in the set (especially |
|
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406 | on SMP systems). Libev tries to counter these spurious notifications by |
|
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407 | employing an additional generation counter and comparing that against the |
|
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408 | events to filter out spurious ones, recreating the set when required. |
389 | |
409 | |
390 | While stopping, setting and starting an I/O watcher in the same iteration |
410 | While stopping, setting and starting an I/O watcher in the same iteration |
391 | will result in some caching, there is still a system call per such incident |
411 | will result in some caching, there is still a system call per such |
392 | (because the fd could point to a different file description now), so its |
412 | incident (because the same I<file descriptor> could point to a different |
393 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
413 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
394 | very well if you register events for both fds. |
414 | file descriptors might not work very well if you register events for both |
395 | |
415 | file descriptors. |
396 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
397 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
398 | (or space) is available. |
|
|
399 | |
416 | |
400 | Best performance from this backend is achieved by not unregistering all |
417 | Best performance from this backend is achieved by not unregistering all |
401 | watchers for a file descriptor until it has been closed, if possible, |
418 | watchers for a file descriptor until it has been closed, if possible, |
402 | i.e. keep at least one watcher active per fd at all times. Stopping and |
419 | i.e. keep at least one watcher active per fd at all times. Stopping and |
403 | starting a watcher (without re-setting it) also usually doesn't cause |
420 | starting a watcher (without re-setting it) also usually doesn't cause |
404 | extra overhead. |
421 | extra overhead. A fork can both result in spurious notifications as well |
|
|
422 | as in libev having to destroy and recreate the epoll object, which can |
|
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423 | take considerable time and thus should be avoided. |
|
|
424 | |
|
|
425 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
|
|
426 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
427 | the usage. So sad. |
405 | |
428 | |
406 | While nominally embeddable in other event loops, this feature is broken in |
429 | While nominally embeddable in other event loops, this feature is broken in |
407 | all kernel versions tested so far. |
430 | all kernel versions tested so far. |
408 | |
431 | |
409 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
432 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
410 | C<EVBACKEND_POLL>. |
433 | C<EVBACKEND_POLL>. |
411 | |
434 | |
412 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
435 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
413 | |
436 | |
414 | Kqueue deserves special mention, as at the time of this writing, it was |
437 | Kqueue deserves special mention, as at the time of this writing, it |
415 | broken on all BSDs except NetBSD (usually it doesn't work reliably with |
438 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
416 | anything but sockets and pipes, except on Darwin, where of course it's |
439 | with anything but sockets and pipes, except on Darwin, where of course |
417 | completely useless). For this reason it's not being "auto-detected" unless |
440 | it's completely useless). Unlike epoll, however, whose brokenness |
418 | you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or |
441 | is by design, these kqueue bugs can (and eventually will) be fixed |
419 | libev was compiled on a known-to-be-good (-enough) system like NetBSD. |
442 | without API changes to existing programs. For this reason it's not being |
|
|
443 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
|
|
444 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
445 | system like NetBSD. |
420 | |
446 | |
421 | You still can embed kqueue into a normal poll or select backend and use it |
447 | You still can embed kqueue into a normal poll or select backend and use it |
422 | only for sockets (after having made sure that sockets work with kqueue on |
448 | only for sockets (after having made sure that sockets work with kqueue on |
423 | the target platform). See C<ev_embed> watchers for more info. |
449 | the target platform). See C<ev_embed> watchers for more info. |
424 | |
450 | |
425 | It scales in the same way as the epoll backend, but the interface to the |
451 | It scales in the same way as the epoll backend, but the interface to the |
426 | kernel is more efficient (which says nothing about its actual speed, of |
452 | kernel is more efficient (which says nothing about its actual speed, of |
427 | course). While stopping, setting and starting an I/O watcher does never |
453 | course). While stopping, setting and starting an I/O watcher does never |
428 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
454 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
429 | two event changes per incident. Support for C<fork ()> is very bad and it |
455 | two event changes per incident. Support for C<fork ()> is very bad (but |
430 | drops fds silently in similarly hard-to-detect cases. |
456 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
457 | cases |
431 | |
458 | |
432 | This backend usually performs well under most conditions. |
459 | This backend usually performs well under most conditions. |
433 | |
460 | |
434 | While nominally embeddable in other event loops, this doesn't work |
461 | While nominally embeddable in other event loops, this doesn't work |
435 | everywhere, so you might need to test for this. And since it is broken |
462 | everywhere, so you might need to test for this. And since it is broken |
436 | almost everywhere, you should only use it when you have a lot of sockets |
463 | almost everywhere, you should only use it when you have a lot of sockets |
437 | (for which it usually works), by embedding it into another event loop |
464 | (for which it usually works), by embedding it into another event loop |
438 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
465 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
439 | using it only for sockets. |
466 | also broken on OS X)) and, did I mention it, using it only for sockets. |
440 | |
467 | |
441 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
468 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
442 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
469 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
443 | C<NOTE_EOF>. |
470 | C<NOTE_EOF>. |
444 | |
471 | |
… | |
… | |
464 | might perform better. |
491 | might perform better. |
465 | |
492 | |
466 | On the positive side, with the exception of the spurious readiness |
493 | On the positive side, with the exception of the spurious readiness |
467 | notifications, this backend actually performed fully to specification |
494 | notifications, this backend actually performed fully to specification |
468 | in all tests and is fully embeddable, which is a rare feat among the |
495 | in all tests and is fully embeddable, which is a rare feat among the |
469 | OS-specific backends. |
496 | OS-specific backends (I vastly prefer correctness over speed hacks). |
470 | |
497 | |
471 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
498 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
472 | C<EVBACKEND_POLL>. |
499 | C<EVBACKEND_POLL>. |
473 | |
500 | |
474 | =item C<EVBACKEND_ALL> |
501 | =item C<EVBACKEND_ALL> |
… | |
… | |
527 | responsibility to either stop all watchers cleanly yourself I<before> |
554 | responsibility to either stop all watchers cleanly yourself I<before> |
528 | calling this function, or cope with the fact afterwards (which is usually |
555 | calling this function, or cope with the fact afterwards (which is usually |
529 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
556 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
530 | for example). |
557 | for example). |
531 | |
558 | |
532 | Note that certain global state, such as signal state, will not be freed by |
559 | Note that certain global state, such as signal state (and installed signal |
533 | this function, and related watchers (such as signal and child watchers) |
560 | handlers), will not be freed by this function, and related watchers (such |
534 | would need to be stopped manually. |
561 | as signal and child watchers) would need to be stopped manually. |
535 | |
562 | |
536 | In general it is not advisable to call this function except in the |
563 | In general it is not advisable to call this function except in the |
537 | rare occasion where you really need to free e.g. the signal handling |
564 | rare occasion where you really need to free e.g. the signal handling |
538 | pipe fds. If you need dynamically allocated loops it is better to use |
565 | pipe fds. If you need dynamically allocated loops it is better to use |
539 | C<ev_loop_new> and C<ev_loop_destroy>). |
566 | C<ev_loop_new> and C<ev_loop_destroy>). |
… | |
… | |
607 | very long time without entering the event loop, updating libev's idea of |
634 | very long time without entering the event loop, updating libev's idea of |
608 | the current time is a good idea. |
635 | the current time is a good idea. |
609 | |
636 | |
610 | See also "The special problem of time updates" in the C<ev_timer> section. |
637 | See also "The special problem of time updates" in the C<ev_timer> section. |
611 | |
638 | |
|
|
639 | =item ev_suspend (loop) |
|
|
640 | |
|
|
641 | =item ev_resume (loop) |
|
|
642 | |
|
|
643 | These two functions suspend and resume a loop, for use when the loop is |
|
|
644 | not used for a while and timeouts should not be processed. |
|
|
645 | |
|
|
646 | A typical use case would be an interactive program such as a game: When |
|
|
647 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
|
|
648 | would be best to handle timeouts as if no time had actually passed while |
|
|
649 | the program was suspended. This can be achieved by calling C<ev_suspend> |
|
|
650 | in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling |
|
|
651 | C<ev_resume> directly afterwards to resume timer processing. |
|
|
652 | |
|
|
653 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
|
|
654 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
|
|
655 | will be rescheduled (that is, they will lose any events that would have |
|
|
656 | occured while suspended). |
|
|
657 | |
|
|
658 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
|
|
659 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
|
|
660 | without a previous call to C<ev_suspend>. |
|
|
661 | |
|
|
662 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
|
|
663 | event loop time (see C<ev_now_update>). |
|
|
664 | |
612 | =item ev_loop (loop, int flags) |
665 | =item ev_loop (loop, int flags) |
613 | |
666 | |
614 | Finally, this is it, the event handler. This function usually is called |
667 | Finally, this is it, the event handler. This function usually is called |
615 | after you initialised all your watchers and you want to start handling |
668 | after you initialised all your watchers and you want to start handling |
616 | events. |
669 | events. |
… | |
… | |
631 | the loop. |
684 | the loop. |
632 | |
685 | |
633 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
686 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
634 | necessary) and will handle those and any already outstanding ones. It |
687 | necessary) and will handle those and any already outstanding ones. It |
635 | will block your process until at least one new event arrives (which could |
688 | will block your process until at least one new event arrives (which could |
636 | be an event internal to libev itself, so there is no guarentee that a |
689 | be an event internal to libev itself, so there is no guarantee that a |
637 | user-registered callback will be called), and will return after one |
690 | user-registered callback will be called), and will return after one |
638 | iteration of the loop. |
691 | iteration of the loop. |
639 | |
692 | |
640 | This is useful if you are waiting for some external event in conjunction |
693 | This is useful if you are waiting for some external event in conjunction |
641 | with something not expressible using other libev watchers (i.e. "roll your |
694 | with something not expressible using other libev watchers (i.e. "roll your |
… | |
… | |
699 | |
752 | |
700 | If you have a watcher you never unregister that should not keep C<ev_loop> |
753 | If you have a watcher you never unregister that should not keep C<ev_loop> |
701 | from returning, call ev_unref() after starting, and ev_ref() before |
754 | from returning, call ev_unref() after starting, and ev_ref() before |
702 | stopping it. |
755 | stopping it. |
703 | |
756 | |
704 | As an example, libev itself uses this for its internal signal pipe: It is |
757 | As an example, libev itself uses this for its internal signal pipe: It |
705 | not visible to the libev user and should not keep C<ev_loop> from exiting |
758 | is not visible to the libev user and should not keep C<ev_loop> from |
706 | if no event watchers registered by it are active. It is also an excellent |
759 | exiting if no event watchers registered by it are active. It is also an |
707 | way to do this for generic recurring timers or from within third-party |
760 | excellent way to do this for generic recurring timers or from within |
708 | libraries. Just remember to I<unref after start> and I<ref before stop> |
761 | third-party libraries. Just remember to I<unref after start> and I<ref |
709 | (but only if the watcher wasn't active before, or was active before, |
762 | before stop> (but only if the watcher wasn't active before, or was active |
710 | respectively). |
763 | before, respectively. Note also that libev might stop watchers itself |
|
|
764 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
|
|
765 | in the callback). |
711 | |
766 | |
712 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
767 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
713 | running when nothing else is active. |
768 | running when nothing else is active. |
714 | |
769 | |
715 | struct ev_signal exitsig; |
770 | ev_signal exitsig; |
716 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
771 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
717 | ev_signal_start (loop, &exitsig); |
772 | ev_signal_start (loop, &exitsig); |
718 | evf_unref (loop); |
773 | evf_unref (loop); |
719 | |
774 | |
720 | Example: For some weird reason, unregister the above signal handler again. |
775 | Example: For some weird reason, unregister the above signal handler again. |
… | |
… | |
768 | they fire on, say, one-second boundaries only. |
823 | they fire on, say, one-second boundaries only. |
769 | |
824 | |
770 | =item ev_loop_verify (loop) |
825 | =item ev_loop_verify (loop) |
771 | |
826 | |
772 | This function only does something when C<EV_VERIFY> support has been |
827 | This function only does something when C<EV_VERIFY> support has been |
773 | compiled in. which is the default for non-minimal builds. It tries to go |
828 | compiled in, which is the default for non-minimal builds. It tries to go |
774 | through all internal structures and checks them for validity. If anything |
829 | through all internal structures and checks them for validity. If anything |
775 | is found to be inconsistent, it will print an error message to standard |
830 | is found to be inconsistent, it will print an error message to standard |
776 | error and call C<abort ()>. |
831 | error and call C<abort ()>. |
777 | |
832 | |
778 | This can be used to catch bugs inside libev itself: under normal |
833 | This can be used to catch bugs inside libev itself: under normal |
… | |
… | |
782 | =back |
837 | =back |
783 | |
838 | |
784 | |
839 | |
785 | =head1 ANATOMY OF A WATCHER |
840 | =head1 ANATOMY OF A WATCHER |
786 | |
841 | |
|
|
842 | In the following description, uppercase C<TYPE> in names stands for the |
|
|
843 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
|
|
844 | watchers and C<ev_io_start> for I/O watchers. |
|
|
845 | |
787 | A watcher is a structure that you create and register to record your |
846 | A watcher is a structure that you create and register to record your |
788 | interest in some event. For instance, if you want to wait for STDIN to |
847 | interest in some event. For instance, if you want to wait for STDIN to |
789 | become readable, you would create an C<ev_io> watcher for that: |
848 | become readable, you would create an C<ev_io> watcher for that: |
790 | |
849 | |
791 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
850 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
792 | { |
851 | { |
793 | ev_io_stop (w); |
852 | ev_io_stop (w); |
794 | ev_unloop (loop, EVUNLOOP_ALL); |
853 | ev_unloop (loop, EVUNLOOP_ALL); |
795 | } |
854 | } |
796 | |
855 | |
797 | struct ev_loop *loop = ev_default_loop (0); |
856 | struct ev_loop *loop = ev_default_loop (0); |
|
|
857 | |
798 | struct ev_io stdin_watcher; |
858 | ev_io stdin_watcher; |
|
|
859 | |
799 | ev_init (&stdin_watcher, my_cb); |
860 | ev_init (&stdin_watcher, my_cb); |
800 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
861 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
801 | ev_io_start (loop, &stdin_watcher); |
862 | ev_io_start (loop, &stdin_watcher); |
|
|
863 | |
802 | ev_loop (loop, 0); |
864 | ev_loop (loop, 0); |
803 | |
865 | |
804 | As you can see, you are responsible for allocating the memory for your |
866 | As you can see, you are responsible for allocating the memory for your |
805 | watcher structures (and it is usually a bad idea to do this on the stack, |
867 | watcher structures (and it is I<usually> a bad idea to do this on the |
806 | although this can sometimes be quite valid). |
868 | stack). |
|
|
869 | |
|
|
870 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
|
|
871 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
807 | |
872 | |
808 | Each watcher structure must be initialised by a call to C<ev_init |
873 | Each watcher structure must be initialised by a call to C<ev_init |
809 | (watcher *, callback)>, which expects a callback to be provided. This |
874 | (watcher *, callback)>, which expects a callback to be provided. This |
810 | callback gets invoked each time the event occurs (or, in the case of I/O |
875 | callback gets invoked each time the event occurs (or, in the case of I/O |
811 | watchers, each time the event loop detects that the file descriptor given |
876 | watchers, each time the event loop detects that the file descriptor given |
812 | is readable and/or writable). |
877 | is readable and/or writable). |
813 | |
878 | |
814 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
879 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
815 | with arguments specific to this watcher type. There is also a macro |
880 | macro to configure it, with arguments specific to the watcher type. There |
816 | to combine initialisation and setting in one call: C<< ev_<type>_init |
881 | is also a macro to combine initialisation and setting in one call: C<< |
817 | (watcher *, callback, ...) >>. |
882 | ev_TYPE_init (watcher *, callback, ...) >>. |
818 | |
883 | |
819 | To make the watcher actually watch out for events, you have to start it |
884 | To make the watcher actually watch out for events, you have to start it |
820 | with a watcher-specific start function (C<< ev_<type>_start (loop, watcher |
885 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
821 | *) >>), and you can stop watching for events at any time by calling the |
886 | *) >>), and you can stop watching for events at any time by calling the |
822 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
887 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
823 | |
888 | |
824 | As long as your watcher is active (has been started but not stopped) you |
889 | As long as your watcher is active (has been started but not stopped) you |
825 | must not touch the values stored in it. Most specifically you must never |
890 | must not touch the values stored in it. Most specifically you must never |
826 | reinitialise it or call its C<set> macro. |
891 | reinitialise it or call its C<ev_TYPE_set> macro. |
827 | |
892 | |
828 | Each and every callback receives the event loop pointer as first, the |
893 | Each and every callback receives the event loop pointer as first, the |
829 | registered watcher structure as second, and a bitset of received events as |
894 | registered watcher structure as second, and a bitset of received events as |
830 | third argument. |
895 | third argument. |
831 | |
896 | |
… | |
… | |
889 | |
954 | |
890 | =item C<EV_ASYNC> |
955 | =item C<EV_ASYNC> |
891 | |
956 | |
892 | The given async watcher has been asynchronously notified (see C<ev_async>). |
957 | The given async watcher has been asynchronously notified (see C<ev_async>). |
893 | |
958 | |
|
|
959 | =item C<EV_CUSTOM> |
|
|
960 | |
|
|
961 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
962 | by libev users to signal watchers (e.g. via C<ev_feed_event>). |
|
|
963 | |
894 | =item C<EV_ERROR> |
964 | =item C<EV_ERROR> |
895 | |
965 | |
896 | An unspecified error has occurred, the watcher has been stopped. This might |
966 | An unspecified error has occurred, the watcher has been stopped. This might |
897 | happen because the watcher could not be properly started because libev |
967 | happen because the watcher could not be properly started because libev |
898 | ran out of memory, a file descriptor was found to be closed or any other |
968 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
969 | problem. Libev considers these application bugs. |
|
|
970 | |
899 | problem. You best act on it by reporting the problem and somehow coping |
971 | You best act on it by reporting the problem and somehow coping with the |
900 | with the watcher being stopped. |
972 | watcher being stopped. Note that well-written programs should not receive |
|
|
973 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
974 | bug in your program. |
901 | |
975 | |
902 | Libev will usually signal a few "dummy" events together with an error, for |
976 | Libev will usually signal a few "dummy" events together with an error, for |
903 | example it might indicate that a fd is readable or writable, and if your |
977 | example it might indicate that a fd is readable or writable, and if your |
904 | callbacks is well-written it can just attempt the operation and cope with |
978 | callbacks is well-written it can just attempt the operation and cope with |
905 | the error from read() or write(). This will not work in multi-threaded |
979 | the error from read() or write(). This will not work in multi-threaded |
… | |
… | |
908 | |
982 | |
909 | =back |
983 | =back |
910 | |
984 | |
911 | =head2 GENERIC WATCHER FUNCTIONS |
985 | =head2 GENERIC WATCHER FUNCTIONS |
912 | |
986 | |
913 | In the following description, C<TYPE> stands for the watcher type, |
|
|
914 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
915 | |
|
|
916 | =over 4 |
987 | =over 4 |
917 | |
988 | |
918 | =item C<ev_init> (ev_TYPE *watcher, callback) |
989 | =item C<ev_init> (ev_TYPE *watcher, callback) |
919 | |
990 | |
920 | This macro initialises the generic portion of a watcher. The contents |
991 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
925 | which rolls both calls into one. |
996 | which rolls both calls into one. |
926 | |
997 | |
927 | You can reinitialise a watcher at any time as long as it has been stopped |
998 | You can reinitialise a watcher at any time as long as it has been stopped |
928 | (or never started) and there are no pending events outstanding. |
999 | (or never started) and there are no pending events outstanding. |
929 | |
1000 | |
930 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
1001 | The callback is always of type C<void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
931 | int revents)>. |
1002 | int revents)>. |
932 | |
1003 | |
933 | Example: Initialise an C<ev_io> watcher in two steps. |
1004 | Example: Initialise an C<ev_io> watcher in two steps. |
934 | |
1005 | |
935 | ev_io w; |
1006 | ev_io w; |
… | |
… | |
1012 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1083 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1013 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1084 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1014 | before watchers with lower priority, but priority will not keep watchers |
1085 | before watchers with lower priority, but priority will not keep watchers |
1015 | from being executed (except for C<ev_idle> watchers). |
1086 | from being executed (except for C<ev_idle> watchers). |
1016 | |
1087 | |
|
|
1088 | See L< |
|
|
1089 | |
1017 | This means that priorities are I<only> used for ordering callback |
1090 | This means that priorities are I<only> used for ordering callback |
1018 | invocation after new events have been received. This is useful, for |
1091 | invocation after new events have been received. This is useful, for |
1019 | example, to reduce latency after idling, or more often, to bind two |
1092 | example, to reduce latency after idling, or more often, to bind two |
1020 | watchers on the same event and make sure one is called first. |
1093 | watchers on the same event and make sure one is called first. |
1021 | |
1094 | |
… | |
… | |
1028 | The default priority used by watchers when no priority has been set is |
1101 | The default priority used by watchers when no priority has been set is |
1029 | always C<0>, which is supposed to not be too high and not be too low :). |
1102 | always C<0>, which is supposed to not be too high and not be too low :). |
1030 | |
1103 | |
1031 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1104 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1032 | fine, as long as you do not mind that the priority value you query might |
1105 | fine, as long as you do not mind that the priority value you query might |
1033 | or might not have been adjusted to be within valid range. |
1106 | or might not have been clamped to the valid range. |
1034 | |
1107 | |
1035 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1108 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1036 | |
1109 | |
1037 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1110 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1038 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1111 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1060 | member, you can also "subclass" the watcher type and provide your own |
1133 | member, you can also "subclass" the watcher type and provide your own |
1061 | data: |
1134 | data: |
1062 | |
1135 | |
1063 | struct my_io |
1136 | struct my_io |
1064 | { |
1137 | { |
1065 | struct ev_io io; |
1138 | ev_io io; |
1066 | int otherfd; |
1139 | int otherfd; |
1067 | void *somedata; |
1140 | void *somedata; |
1068 | struct whatever *mostinteresting; |
1141 | struct whatever *mostinteresting; |
1069 | }; |
1142 | }; |
1070 | |
1143 | |
… | |
… | |
1073 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1146 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1074 | |
1147 | |
1075 | And since your callback will be called with a pointer to the watcher, you |
1148 | And since your callback will be called with a pointer to the watcher, you |
1076 | can cast it back to your own type: |
1149 | can cast it back to your own type: |
1077 | |
1150 | |
1078 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1151 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1079 | { |
1152 | { |
1080 | struct my_io *w = (struct my_io *)w_; |
1153 | struct my_io *w = (struct my_io *)w_; |
1081 | ... |
1154 | ... |
1082 | } |
1155 | } |
1083 | |
1156 | |
… | |
… | |
1101 | programmers): |
1174 | programmers): |
1102 | |
1175 | |
1103 | #include <stddef.h> |
1176 | #include <stddef.h> |
1104 | |
1177 | |
1105 | static void |
1178 | static void |
1106 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1179 | t1_cb (EV_P_ ev_timer *w, int revents) |
1107 | { |
1180 | { |
1108 | struct my_biggy big = (struct my_biggy * |
1181 | struct my_biggy big = (struct my_biggy * |
1109 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1182 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1110 | } |
1183 | } |
1111 | |
1184 | |
1112 | static void |
1185 | static void |
1113 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1186 | t2_cb (EV_P_ ev_timer *w, int revents) |
1114 | { |
1187 | { |
1115 | struct my_biggy big = (struct my_biggy * |
1188 | struct my_biggy big = (struct my_biggy * |
1116 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1189 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1117 | } |
1190 | } |
1118 | |
1191 | |
… | |
… | |
1253 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1326 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1254 | readable, but only once. Since it is likely line-buffered, you could |
1327 | readable, but only once. Since it is likely line-buffered, you could |
1255 | attempt to read a whole line in the callback. |
1328 | attempt to read a whole line in the callback. |
1256 | |
1329 | |
1257 | static void |
1330 | static void |
1258 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1331 | stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
1259 | { |
1332 | { |
1260 | ev_io_stop (loop, w); |
1333 | ev_io_stop (loop, w); |
1261 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1334 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1262 | } |
1335 | } |
1263 | |
1336 | |
1264 | ... |
1337 | ... |
1265 | struct ev_loop *loop = ev_default_init (0); |
1338 | struct ev_loop *loop = ev_default_init (0); |
1266 | struct ev_io stdin_readable; |
1339 | ev_io stdin_readable; |
1267 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1340 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1268 | ev_io_start (loop, &stdin_readable); |
1341 | ev_io_start (loop, &stdin_readable); |
1269 | ev_loop (loop, 0); |
1342 | ev_loop (loop, 0); |
1270 | |
1343 | |
1271 | |
1344 | |
… | |
… | |
1279 | year, it will still time out after (roughly) one hour. "Roughly" because |
1352 | year, it will still time out after (roughly) one hour. "Roughly" because |
1280 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1353 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1281 | monotonic clock option helps a lot here). |
1354 | monotonic clock option helps a lot here). |
1282 | |
1355 | |
1283 | The callback is guaranteed to be invoked only I<after> its timeout has |
1356 | The callback is guaranteed to be invoked only I<after> its timeout has |
1284 | passed, but if multiple timers become ready during the same loop iteration |
1357 | passed. If multiple timers become ready during the same loop iteration |
1285 | then order of execution is undefined. |
1358 | then the ones with earlier time-out values are invoked before ones with |
|
|
1359 | later time-out values (but this is no longer true when a callback calls |
|
|
1360 | C<ev_loop> recursively). |
|
|
1361 | |
|
|
1362 | =head3 Be smart about timeouts |
|
|
1363 | |
|
|
1364 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1365 | recovery. A typical example is an HTTP request - if the other side hangs, |
|
|
1366 | you want to raise some error after a while. |
|
|
1367 | |
|
|
1368 | What follows are some ways to handle this problem, from obvious and |
|
|
1369 | inefficient to smart and efficient. |
|
|
1370 | |
|
|
1371 | In the following, a 60 second activity timeout is assumed - a timeout that |
|
|
1372 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1373 | data or other life sign was received). |
|
|
1374 | |
|
|
1375 | =over 4 |
|
|
1376 | |
|
|
1377 | =item 1. Use a timer and stop, reinitialise and start it on activity. |
|
|
1378 | |
|
|
1379 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1380 | start the watcher: |
|
|
1381 | |
|
|
1382 | ev_timer_init (timer, callback, 60., 0.); |
|
|
1383 | ev_timer_start (loop, timer); |
|
|
1384 | |
|
|
1385 | Then, each time there is some activity, C<ev_timer_stop> it, initialise it |
|
|
1386 | and start it again: |
|
|
1387 | |
|
|
1388 | ev_timer_stop (loop, timer); |
|
|
1389 | ev_timer_set (timer, 60., 0.); |
|
|
1390 | ev_timer_start (loop, timer); |
|
|
1391 | |
|
|
1392 | This is relatively simple to implement, but means that each time there is |
|
|
1393 | some activity, libev will first have to remove the timer from its internal |
|
|
1394 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1395 | still not a constant-time operation. |
|
|
1396 | |
|
|
1397 | =item 2. Use a timer and re-start it with C<ev_timer_again> inactivity. |
|
|
1398 | |
|
|
1399 | This is the easiest way, and involves using C<ev_timer_again> instead of |
|
|
1400 | C<ev_timer_start>. |
|
|
1401 | |
|
|
1402 | To implement this, configure an C<ev_timer> with a C<repeat> value |
|
|
1403 | of C<60> and then call C<ev_timer_again> at start and each time you |
|
|
1404 | successfully read or write some data. If you go into an idle state where |
|
|
1405 | you do not expect data to travel on the socket, you can C<ev_timer_stop> |
|
|
1406 | the timer, and C<ev_timer_again> will automatically restart it if need be. |
|
|
1407 | |
|
|
1408 | That means you can ignore both the C<ev_timer_start> function and the |
|
|
1409 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
|
|
1410 | member and C<ev_timer_again>. |
|
|
1411 | |
|
|
1412 | At start: |
|
|
1413 | |
|
|
1414 | ev_timer_init (timer, callback); |
|
|
1415 | timer->repeat = 60.; |
|
|
1416 | ev_timer_again (loop, timer); |
|
|
1417 | |
|
|
1418 | Each time there is some activity: |
|
|
1419 | |
|
|
1420 | ev_timer_again (loop, timer); |
|
|
1421 | |
|
|
1422 | It is even possible to change the time-out on the fly, regardless of |
|
|
1423 | whether the watcher is active or not: |
|
|
1424 | |
|
|
1425 | timer->repeat = 30.; |
|
|
1426 | ev_timer_again (loop, timer); |
|
|
1427 | |
|
|
1428 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1429 | you want to modify its timeout value, as libev does not have to completely |
|
|
1430 | remove and re-insert the timer from/into its internal data structure. |
|
|
1431 | |
|
|
1432 | It is, however, even simpler than the "obvious" way to do it. |
|
|
1433 | |
|
|
1434 | =item 3. Let the timer time out, but then re-arm it as required. |
|
|
1435 | |
|
|
1436 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1437 | relatively long compared to the intervals between other activity - in |
|
|
1438 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1439 | associated activity resets. |
|
|
1440 | |
|
|
1441 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
|
|
1442 | but remember the time of last activity, and check for a real timeout only |
|
|
1443 | within the callback: |
|
|
1444 | |
|
|
1445 | ev_tstamp last_activity; // time of last activity |
|
|
1446 | |
|
|
1447 | static void |
|
|
1448 | callback (EV_P_ ev_timer *w, int revents) |
|
|
1449 | { |
|
|
1450 | ev_tstamp now = ev_now (EV_A); |
|
|
1451 | ev_tstamp timeout = last_activity + 60.; |
|
|
1452 | |
|
|
1453 | // if last_activity + 60. is older than now, we did time out |
|
|
1454 | if (timeout < now) |
|
|
1455 | { |
|
|
1456 | // timeout occured, take action |
|
|
1457 | } |
|
|
1458 | else |
|
|
1459 | { |
|
|
1460 | // callback was invoked, but there was some activity, re-arm |
|
|
1461 | // the watcher to fire in last_activity + 60, which is |
|
|
1462 | // guaranteed to be in the future, so "again" is positive: |
|
|
1463 | w->repeat = timeout - now; |
|
|
1464 | ev_timer_again (EV_A_ w); |
|
|
1465 | } |
|
|
1466 | } |
|
|
1467 | |
|
|
1468 | To summarise the callback: first calculate the real timeout (defined |
|
|
1469 | as "60 seconds after the last activity"), then check if that time has |
|
|
1470 | been reached, which means something I<did>, in fact, time out. Otherwise |
|
|
1471 | the callback was invoked too early (C<timeout> is in the future), so |
|
|
1472 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1473 | a timeout then. |
|
|
1474 | |
|
|
1475 | Note how C<ev_timer_again> is used, taking advantage of the |
|
|
1476 | C<ev_timer_again> optimisation when the timer is already running. |
|
|
1477 | |
|
|
1478 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1479 | minus half the average time between activity), but virtually no calls to |
|
|
1480 | libev to change the timeout. |
|
|
1481 | |
|
|
1482 | To start the timer, simply initialise the watcher and set C<last_activity> |
|
|
1483 | to the current time (meaning we just have some activity :), then call the |
|
|
1484 | callback, which will "do the right thing" and start the timer: |
|
|
1485 | |
|
|
1486 | ev_timer_init (timer, callback); |
|
|
1487 | last_activity = ev_now (loop); |
|
|
1488 | callback (loop, timer, EV_TIMEOUT); |
|
|
1489 | |
|
|
1490 | And when there is some activity, simply store the current time in |
|
|
1491 | C<last_activity>, no libev calls at all: |
|
|
1492 | |
|
|
1493 | last_actiivty = ev_now (loop); |
|
|
1494 | |
|
|
1495 | This technique is slightly more complex, but in most cases where the |
|
|
1496 | time-out is unlikely to be triggered, much more efficient. |
|
|
1497 | |
|
|
1498 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1499 | callback :) - just change the timeout and invoke the callback, which will |
|
|
1500 | fix things for you. |
|
|
1501 | |
|
|
1502 | =item 4. Wee, just use a double-linked list for your timeouts. |
|
|
1503 | |
|
|
1504 | If there is not one request, but many thousands (millions...), all |
|
|
1505 | employing some kind of timeout with the same timeout value, then one can |
|
|
1506 | do even better: |
|
|
1507 | |
|
|
1508 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1509 | at the I<end> of the list. |
|
|
1510 | |
|
|
1511 | Then use an C<ev_timer> to fire when the timeout at the I<beginning> of |
|
|
1512 | the list is expected to fire (for example, using the technique #3). |
|
|
1513 | |
|
|
1514 | When there is some activity, remove the timer from the list, recalculate |
|
|
1515 | the timeout, append it to the end of the list again, and make sure to |
|
|
1516 | update the C<ev_timer> if it was taken from the beginning of the list. |
|
|
1517 | |
|
|
1518 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1519 | starting, stopping and updating the timers, at the expense of a major |
|
|
1520 | complication, and having to use a constant timeout. The constant timeout |
|
|
1521 | ensures that the list stays sorted. |
|
|
1522 | |
|
|
1523 | =back |
|
|
1524 | |
|
|
1525 | So which method the best? |
|
|
1526 | |
|
|
1527 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1528 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1529 | better, and isn't very complicated either. In most case, choosing either |
|
|
1530 | one is fine, with #3 being better in typical situations. |
|
|
1531 | |
|
|
1532 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1533 | rather complicated, but extremely efficient, something that really pays |
|
|
1534 | off after the first million or so of active timers, i.e. it's usually |
|
|
1535 | overkill :) |
1286 | |
1536 | |
1287 | =head3 The special problem of time updates |
1537 | =head3 The special problem of time updates |
1288 | |
1538 | |
1289 | Establishing the current time is a costly operation (it usually takes at |
1539 | Establishing the current time is a costly operation (it usually takes at |
1290 | least two system calls): EV therefore updates its idea of the current |
1540 | least two system calls): EV therefore updates its idea of the current |
… | |
… | |
1334 | If the timer is started but non-repeating, stop it (as if it timed out). |
1584 | If the timer is started but non-repeating, stop it (as if it timed out). |
1335 | |
1585 | |
1336 | If the timer is repeating, either start it if necessary (with the |
1586 | If the timer is repeating, either start it if necessary (with the |
1337 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1587 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1338 | |
1588 | |
1339 | This sounds a bit complicated, but here is a useful and typical |
1589 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1340 | example: Imagine you have a TCP connection and you want a so-called idle |
1590 | usage example. |
1341 | timeout, that is, you want to be called when there have been, say, 60 |
|
|
1342 | seconds of inactivity on the socket. The easiest way to do this is to |
|
|
1343 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
|
|
1344 | C<ev_timer_again> each time you successfully read or write some data. If |
|
|
1345 | you go into an idle state where you do not expect data to travel on the |
|
|
1346 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1347 | automatically restart it if need be. |
|
|
1348 | |
|
|
1349 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1350 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1351 | |
|
|
1352 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1353 | ev_timer_again (loop, timer); |
|
|
1354 | ... |
|
|
1355 | timer->again = 17.; |
|
|
1356 | ev_timer_again (loop, timer); |
|
|
1357 | ... |
|
|
1358 | timer->again = 10.; |
|
|
1359 | ev_timer_again (loop, timer); |
|
|
1360 | |
|
|
1361 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1362 | you want to modify its timeout value. |
|
|
1363 | |
|
|
1364 | Note, however, that it is often even more efficient to remember the |
|
|
1365 | time of the last activity and let the timer time-out naturally. In the |
|
|
1366 | callback, you then check whether the time-out is real, or, if there was |
|
|
1367 | some activity, you reschedule the watcher to time-out in "last_activity + |
|
|
1368 | timeout - ev_now ()" seconds. |
|
|
1369 | |
1591 | |
1370 | =item ev_tstamp repeat [read-write] |
1592 | =item ev_tstamp repeat [read-write] |
1371 | |
1593 | |
1372 | The current C<repeat> value. Will be used each time the watcher times out |
1594 | The current C<repeat> value. Will be used each time the watcher times out |
1373 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1595 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1378 | =head3 Examples |
1600 | =head3 Examples |
1379 | |
1601 | |
1380 | Example: Create a timer that fires after 60 seconds. |
1602 | Example: Create a timer that fires after 60 seconds. |
1381 | |
1603 | |
1382 | static void |
1604 | static void |
1383 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1605 | one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1384 | { |
1606 | { |
1385 | .. one minute over, w is actually stopped right here |
1607 | .. one minute over, w is actually stopped right here |
1386 | } |
1608 | } |
1387 | |
1609 | |
1388 | struct ev_timer mytimer; |
1610 | ev_timer mytimer; |
1389 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1611 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1390 | ev_timer_start (loop, &mytimer); |
1612 | ev_timer_start (loop, &mytimer); |
1391 | |
1613 | |
1392 | Example: Create a timeout timer that times out after 10 seconds of |
1614 | Example: Create a timeout timer that times out after 10 seconds of |
1393 | inactivity. |
1615 | inactivity. |
1394 | |
1616 | |
1395 | static void |
1617 | static void |
1396 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1618 | timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1397 | { |
1619 | { |
1398 | .. ten seconds without any activity |
1620 | .. ten seconds without any activity |
1399 | } |
1621 | } |
1400 | |
1622 | |
1401 | struct ev_timer mytimer; |
1623 | ev_timer mytimer; |
1402 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1624 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1403 | ev_timer_again (&mytimer); /* start timer */ |
1625 | ev_timer_again (&mytimer); /* start timer */ |
1404 | ev_loop (loop, 0); |
1626 | ev_loop (loop, 0); |
1405 | |
1627 | |
1406 | // and in some piece of code that gets executed on any "activity": |
1628 | // and in some piece of code that gets executed on any "activity": |
… | |
… | |
1411 | =head2 C<ev_periodic> - to cron or not to cron? |
1633 | =head2 C<ev_periodic> - to cron or not to cron? |
1412 | |
1634 | |
1413 | Periodic watchers are also timers of a kind, but they are very versatile |
1635 | Periodic watchers are also timers of a kind, but they are very versatile |
1414 | (and unfortunately a bit complex). |
1636 | (and unfortunately a bit complex). |
1415 | |
1637 | |
1416 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1638 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1417 | but on wall clock time (absolute time). You can tell a periodic watcher |
1639 | relative time, the physical time that passes) but on wall clock time |
1418 | to trigger after some specific point in time. For example, if you tell a |
1640 | (absolute time, the thing you can read on your calender or clock). The |
1419 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1641 | difference is that wall clock time can run faster or slower than real |
1420 | + 10.>, that is, an absolute time not a delay) and then reset your system |
1642 | time, and time jumps are not uncommon (e.g. when you adjust your |
1421 | clock to January of the previous year, then it will take more than year |
1643 | wrist-watch). |
1422 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
|
|
1423 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1424 | |
1644 | |
|
|
1645 | You can tell a periodic watcher to trigger after some specific point |
|
|
1646 | in time: for example, if you tell a periodic watcher to trigger "in 10 |
|
|
1647 | seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time |
|
|
1648 | not a delay) and then reset your system clock to January of the previous |
|
|
1649 | year, then it will take a year or more to trigger the event (unlike an |
|
|
1650 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
|
|
1651 | it, as it uses a relative timeout). |
|
|
1652 | |
1425 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1653 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1426 | such as triggering an event on each "midnight, local time", or other |
1654 | timers, such as triggering an event on each "midnight, local time", or |
1427 | complicated rules. |
1655 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
|
|
1656 | those cannot react to time jumps. |
1428 | |
1657 | |
1429 | As with timers, the callback is guaranteed to be invoked only when the |
1658 | As with timers, the callback is guaranteed to be invoked only when the |
1430 | time (C<at>) has passed, but if multiple periodic timers become ready |
1659 | point in time where it is supposed to trigger has passed. If multiple |
1431 | during the same loop iteration, then order of execution is undefined. |
1660 | timers become ready during the same loop iteration then the ones with |
|
|
1661 | earlier time-out values are invoked before ones with later time-out values |
|
|
1662 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
1432 | |
1663 | |
1433 | =head3 Watcher-Specific Functions and Data Members |
1664 | =head3 Watcher-Specific Functions and Data Members |
1434 | |
1665 | |
1435 | =over 4 |
1666 | =over 4 |
1436 | |
1667 | |
1437 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1668 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1438 | |
1669 | |
1439 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1670 | =item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1440 | |
1671 | |
1441 | Lots of arguments, lets sort it out... There are basically three modes of |
1672 | Lots of arguments, let's sort it out... There are basically three modes of |
1442 | operation, and we will explain them from simplest to most complex: |
1673 | operation, and we will explain them from simplest to most complex: |
1443 | |
1674 | |
1444 | =over 4 |
1675 | =over 4 |
1445 | |
1676 | |
1446 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1677 | =item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1447 | |
1678 | |
1448 | In this configuration the watcher triggers an event after the wall clock |
1679 | In this configuration the watcher triggers an event after the wall clock |
1449 | time C<at> has passed. It will not repeat and will not adjust when a time |
1680 | time C<offset> has passed. It will not repeat and will not adjust when a |
1450 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1681 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1451 | only run when the system clock reaches or surpasses this time. |
1682 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
1683 | this point in time. |
1452 | |
1684 | |
1453 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1685 | =item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1454 | |
1686 | |
1455 | In this mode the watcher will always be scheduled to time out at the next |
1687 | In this mode the watcher will always be scheduled to time out at the next |
1456 | C<at + N * interval> time (for some integer N, which can also be negative) |
1688 | C<offset + N * interval> time (for some integer N, which can also be |
1457 | and then repeat, regardless of any time jumps. |
1689 | negative) and then repeat, regardless of any time jumps. The C<offset> |
|
|
1690 | argument is merely an offset into the C<interval> periods. |
1458 | |
1691 | |
1459 | This can be used to create timers that do not drift with respect to the |
1692 | This can be used to create timers that do not drift with respect to the |
1460 | system clock, for example, here is a C<ev_periodic> that triggers each |
1693 | system clock, for example, here is an C<ev_periodic> that triggers each |
1461 | hour, on the hour: |
1694 | hour, on the hour (with respect to UTC): |
1462 | |
1695 | |
1463 | ev_periodic_set (&periodic, 0., 3600., 0); |
1696 | ev_periodic_set (&periodic, 0., 3600., 0); |
1464 | |
1697 | |
1465 | This doesn't mean there will always be 3600 seconds in between triggers, |
1698 | This doesn't mean there will always be 3600 seconds in between triggers, |
1466 | but only that the callback will be called when the system time shows a |
1699 | but only that the callback will be called when the system time shows a |
1467 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1700 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1468 | by 3600. |
1701 | by 3600. |
1469 | |
1702 | |
1470 | Another way to think about it (for the mathematically inclined) is that |
1703 | Another way to think about it (for the mathematically inclined) is that |
1471 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1704 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1472 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1705 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1473 | |
1706 | |
1474 | For numerical stability it is preferable that the C<at> value is near |
1707 | For numerical stability it is preferable that the C<offset> value is near |
1475 | C<ev_now ()> (the current time), but there is no range requirement for |
1708 | C<ev_now ()> (the current time), but there is no range requirement for |
1476 | this value, and in fact is often specified as zero. |
1709 | this value, and in fact is often specified as zero. |
1477 | |
1710 | |
1478 | Note also that there is an upper limit to how often a timer can fire (CPU |
1711 | Note also that there is an upper limit to how often a timer can fire (CPU |
1479 | speed for example), so if C<interval> is very small then timing stability |
1712 | speed for example), so if C<interval> is very small then timing stability |
1480 | will of course deteriorate. Libev itself tries to be exact to be about one |
1713 | will of course deteriorate. Libev itself tries to be exact to be about one |
1481 | millisecond (if the OS supports it and the machine is fast enough). |
1714 | millisecond (if the OS supports it and the machine is fast enough). |
1482 | |
1715 | |
1483 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1716 | =item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1484 | |
1717 | |
1485 | In this mode the values for C<interval> and C<at> are both being |
1718 | In this mode the values for C<interval> and C<offset> are both being |
1486 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1719 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1487 | reschedule callback will be called with the watcher as first, and the |
1720 | reschedule callback will be called with the watcher as first, and the |
1488 | current time as second argument. |
1721 | current time as second argument. |
1489 | |
1722 | |
1490 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1723 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever, |
1491 | ever, or make ANY event loop modifications whatsoever>. |
1724 | or make ANY other event loop modifications whatsoever, unless explicitly |
|
|
1725 | allowed by documentation here>. |
1492 | |
1726 | |
1493 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1727 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1494 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1728 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1495 | only event loop modification you are allowed to do). |
1729 | only event loop modification you are allowed to do). |
1496 | |
1730 | |
1497 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1731 | The callback prototype is C<ev_tstamp (*reschedule_cb)(ev_periodic |
1498 | *w, ev_tstamp now)>, e.g.: |
1732 | *w, ev_tstamp now)>, e.g.: |
1499 | |
1733 | |
|
|
1734 | static ev_tstamp |
1500 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1735 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
1501 | { |
1736 | { |
1502 | return now + 60.; |
1737 | return now + 60.; |
1503 | } |
1738 | } |
1504 | |
1739 | |
1505 | It must return the next time to trigger, based on the passed time value |
1740 | It must return the next time to trigger, based on the passed time value |
… | |
… | |
1525 | a different time than the last time it was called (e.g. in a crond like |
1760 | a different time than the last time it was called (e.g. in a crond like |
1526 | program when the crontabs have changed). |
1761 | program when the crontabs have changed). |
1527 | |
1762 | |
1528 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1763 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1529 | |
1764 | |
1530 | When active, returns the absolute time that the watcher is supposed to |
1765 | When active, returns the absolute time that the watcher is supposed |
1531 | trigger next. |
1766 | to trigger next. This is not the same as the C<offset> argument to |
|
|
1767 | C<ev_periodic_set>, but indeed works even in interval and manual |
|
|
1768 | rescheduling modes. |
1532 | |
1769 | |
1533 | =item ev_tstamp offset [read-write] |
1770 | =item ev_tstamp offset [read-write] |
1534 | |
1771 | |
1535 | When repeating, this contains the offset value, otherwise this is the |
1772 | When repeating, this contains the offset value, otherwise this is the |
1536 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
1773 | absolute point in time (the C<offset> value passed to C<ev_periodic_set>, |
|
|
1774 | although libev might modify this value for better numerical stability). |
1537 | |
1775 | |
1538 | Can be modified any time, but changes only take effect when the periodic |
1776 | Can be modified any time, but changes only take effect when the periodic |
1539 | timer fires or C<ev_periodic_again> is being called. |
1777 | timer fires or C<ev_periodic_again> is being called. |
1540 | |
1778 | |
1541 | =item ev_tstamp interval [read-write] |
1779 | =item ev_tstamp interval [read-write] |
1542 | |
1780 | |
1543 | The current interval value. Can be modified any time, but changes only |
1781 | The current interval value. Can be modified any time, but changes only |
1544 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1782 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1545 | called. |
1783 | called. |
1546 | |
1784 | |
1547 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1785 | =item ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write] |
1548 | |
1786 | |
1549 | The current reschedule callback, or C<0>, if this functionality is |
1787 | The current reschedule callback, or C<0>, if this functionality is |
1550 | switched off. Can be changed any time, but changes only take effect when |
1788 | switched off. Can be changed any time, but changes only take effect when |
1551 | the periodic timer fires or C<ev_periodic_again> is being called. |
1789 | the periodic timer fires or C<ev_periodic_again> is being called. |
1552 | |
1790 | |
… | |
… | |
1557 | Example: Call a callback every hour, or, more precisely, whenever the |
1795 | Example: Call a callback every hour, or, more precisely, whenever the |
1558 | system time is divisible by 3600. The callback invocation times have |
1796 | system time is divisible by 3600. The callback invocation times have |
1559 | potentially a lot of jitter, but good long-term stability. |
1797 | potentially a lot of jitter, but good long-term stability. |
1560 | |
1798 | |
1561 | static void |
1799 | static void |
1562 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1800 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1563 | { |
1801 | { |
1564 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1802 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1565 | } |
1803 | } |
1566 | |
1804 | |
1567 | struct ev_periodic hourly_tick; |
1805 | ev_periodic hourly_tick; |
1568 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1806 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1569 | ev_periodic_start (loop, &hourly_tick); |
1807 | ev_periodic_start (loop, &hourly_tick); |
1570 | |
1808 | |
1571 | Example: The same as above, but use a reschedule callback to do it: |
1809 | Example: The same as above, but use a reschedule callback to do it: |
1572 | |
1810 | |
1573 | #include <math.h> |
1811 | #include <math.h> |
1574 | |
1812 | |
1575 | static ev_tstamp |
1813 | static ev_tstamp |
1576 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1814 | my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1577 | { |
1815 | { |
1578 | return now + (3600. - fmod (now, 3600.)); |
1816 | return now + (3600. - fmod (now, 3600.)); |
1579 | } |
1817 | } |
1580 | |
1818 | |
1581 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1819 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1582 | |
1820 | |
1583 | Example: Call a callback every hour, starting now: |
1821 | Example: Call a callback every hour, starting now: |
1584 | |
1822 | |
1585 | struct ev_periodic hourly_tick; |
1823 | ev_periodic hourly_tick; |
1586 | ev_periodic_init (&hourly_tick, clock_cb, |
1824 | ev_periodic_init (&hourly_tick, clock_cb, |
1587 | fmod (ev_now (loop), 3600.), 3600., 0); |
1825 | fmod (ev_now (loop), 3600.), 3600., 0); |
1588 | ev_periodic_start (loop, &hourly_tick); |
1826 | ev_periodic_start (loop, &hourly_tick); |
1589 | |
1827 | |
1590 | |
1828 | |
… | |
… | |
1632 | =head3 Examples |
1870 | =head3 Examples |
1633 | |
1871 | |
1634 | Example: Try to exit cleanly on SIGINT. |
1872 | Example: Try to exit cleanly on SIGINT. |
1635 | |
1873 | |
1636 | static void |
1874 | static void |
1637 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1875 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1638 | { |
1876 | { |
1639 | ev_unloop (loop, EVUNLOOP_ALL); |
1877 | ev_unloop (loop, EVUNLOOP_ALL); |
1640 | } |
1878 | } |
1641 | |
1879 | |
1642 | struct ev_signal signal_watcher; |
1880 | ev_signal signal_watcher; |
1643 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1881 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1644 | ev_signal_start (loop, &signal_watcher); |
1882 | ev_signal_start (loop, &signal_watcher); |
1645 | |
1883 | |
1646 | |
1884 | |
1647 | =head2 C<ev_child> - watch out for process status changes |
1885 | =head2 C<ev_child> - watch out for process status changes |
… | |
… | |
1722 | its completion. |
1960 | its completion. |
1723 | |
1961 | |
1724 | ev_child cw; |
1962 | ev_child cw; |
1725 | |
1963 | |
1726 | static void |
1964 | static void |
1727 | child_cb (EV_P_ struct ev_child *w, int revents) |
1965 | child_cb (EV_P_ ev_child *w, int revents) |
1728 | { |
1966 | { |
1729 | ev_child_stop (EV_A_ w); |
1967 | ev_child_stop (EV_A_ w); |
1730 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1968 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1731 | } |
1969 | } |
1732 | |
1970 | |
… | |
… | |
1747 | |
1985 | |
1748 | |
1986 | |
1749 | =head2 C<ev_stat> - did the file attributes just change? |
1987 | =head2 C<ev_stat> - did the file attributes just change? |
1750 | |
1988 | |
1751 | This watches a file system path for attribute changes. That is, it calls |
1989 | This watches a file system path for attribute changes. That is, it calls |
1752 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1990 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1753 | compared to the last time, invoking the callback if it did. |
1991 | and sees if it changed compared to the last time, invoking the callback if |
|
|
1992 | it did. |
1754 | |
1993 | |
1755 | The path does not need to exist: changing from "path exists" to "path does |
1994 | The path does not need to exist: changing from "path exists" to "path does |
1756 | not exist" is a status change like any other. The condition "path does |
1995 | not exist" is a status change like any other. The condition "path does not |
1757 | not exist" is signified by the C<st_nlink> field being zero (which is |
1996 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
1758 | otherwise always forced to be at least one) and all the other fields of |
1997 | C<st_nlink> field being zero (which is otherwise always forced to be at |
1759 | the stat buffer having unspecified contents. |
1998 | least one) and all the other fields of the stat buffer having unspecified |
|
|
1999 | contents. |
1760 | |
2000 | |
1761 | The path I<should> be absolute and I<must not> end in a slash. If it is |
2001 | The path I<must not> end in a slash or contain special components such as |
|
|
2002 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1762 | relative and your working directory changes, the behaviour is undefined. |
2003 | your working directory changes, then the behaviour is undefined. |
1763 | |
2004 | |
1764 | Since there is no standard kernel interface to do this, the portable |
2005 | Since there is no portable change notification interface available, the |
1765 | implementation simply calls C<stat (2)> regularly on the path to see if |
2006 | portable implementation simply calls C<stat(2)> regularly on the path |
1766 | it changed somehow. You can specify a recommended polling interval for |
2007 | to see if it changed somehow. You can specify a recommended polling |
1767 | this case. If you specify a polling interval of C<0> (highly recommended!) |
2008 | interval for this case. If you specify a polling interval of C<0> (highly |
1768 | then a I<suitable, unspecified default> value will be used (which |
2009 | recommended!) then a I<suitable, unspecified default> value will be used |
1769 | you can expect to be around five seconds, although this might change |
2010 | (which you can expect to be around five seconds, although this might |
1770 | dynamically). Libev will also impose a minimum interval which is currently |
2011 | change dynamically). Libev will also impose a minimum interval which is |
1771 | around C<0.1>, but thats usually overkill. |
2012 | currently around C<0.1>, but that's usually overkill. |
1772 | |
2013 | |
1773 | This watcher type is not meant for massive numbers of stat watchers, |
2014 | This watcher type is not meant for massive numbers of stat watchers, |
1774 | as even with OS-supported change notifications, this can be |
2015 | as even with OS-supported change notifications, this can be |
1775 | resource-intensive. |
2016 | resource-intensive. |
1776 | |
2017 | |
1777 | At the time of this writing, the only OS-specific interface implemented |
2018 | At the time of this writing, the only OS-specific interface implemented |
1778 | is the Linux inotify interface (implementing kqueue support is left as |
2019 | is the Linux inotify interface (implementing kqueue support is left as an |
1779 | an exercise for the reader. Note, however, that the author sees no way |
2020 | exercise for the reader. Note, however, that the author sees no way of |
1780 | of implementing C<ev_stat> semantics with kqueue). |
2021 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1781 | |
2022 | |
1782 | =head3 ABI Issues (Largefile Support) |
2023 | =head3 ABI Issues (Largefile Support) |
1783 | |
2024 | |
1784 | Libev by default (unless the user overrides this) uses the default |
2025 | Libev by default (unless the user overrides this) uses the default |
1785 | compilation environment, which means that on systems with large file |
2026 | compilation environment, which means that on systems with large file |
1786 | support disabled by default, you get the 32 bit version of the stat |
2027 | support disabled by default, you get the 32 bit version of the stat |
1787 | structure. When using the library from programs that change the ABI to |
2028 | structure. When using the library from programs that change the ABI to |
1788 | use 64 bit file offsets the programs will fail. In that case you have to |
2029 | use 64 bit file offsets the programs will fail. In that case you have to |
1789 | compile libev with the same flags to get binary compatibility. This is |
2030 | compile libev with the same flags to get binary compatibility. This is |
1790 | obviously the case with any flags that change the ABI, but the problem is |
2031 | obviously the case with any flags that change the ABI, but the problem is |
1791 | most noticeably disabled with ev_stat and large file support. |
2032 | most noticeably displayed with ev_stat and large file support. |
1792 | |
2033 | |
1793 | The solution for this is to lobby your distribution maker to make large |
2034 | The solution for this is to lobby your distribution maker to make large |
1794 | file interfaces available by default (as e.g. FreeBSD does) and not |
2035 | file interfaces available by default (as e.g. FreeBSD does) and not |
1795 | optional. Libev cannot simply switch on large file support because it has |
2036 | optional. Libev cannot simply switch on large file support because it has |
1796 | to exchange stat structures with application programs compiled using the |
2037 | to exchange stat structures with application programs compiled using the |
1797 | default compilation environment. |
2038 | default compilation environment. |
1798 | |
2039 | |
1799 | =head3 Inotify and Kqueue |
2040 | =head3 Inotify and Kqueue |
1800 | |
2041 | |
1801 | When C<inotify (7)> support has been compiled into libev (generally only |
2042 | When C<inotify (7)> support has been compiled into libev and present at |
1802 | available with Linux) and present at runtime, it will be used to speed up |
2043 | runtime, it will be used to speed up change detection where possible. The |
1803 | change detection where possible. The inotify descriptor will be created lazily |
2044 | inotify descriptor will be created lazily when the first C<ev_stat> |
1804 | when the first C<ev_stat> watcher is being started. |
2045 | watcher is being started. |
1805 | |
2046 | |
1806 | Inotify presence does not change the semantics of C<ev_stat> watchers |
2047 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1807 | except that changes might be detected earlier, and in some cases, to avoid |
2048 | except that changes might be detected earlier, and in some cases, to avoid |
1808 | making regular C<stat> calls. Even in the presence of inotify support |
2049 | making regular C<stat> calls. Even in the presence of inotify support |
1809 | there are many cases where libev has to resort to regular C<stat> polling, |
2050 | there are many cases where libev has to resort to regular C<stat> polling, |
1810 | but as long as the path exists, libev usually gets away without polling. |
2051 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2052 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2053 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2054 | xfs are fully working) libev usually gets away without polling. |
1811 | |
2055 | |
1812 | There is no support for kqueue, as apparently it cannot be used to |
2056 | There is no support for kqueue, as apparently it cannot be used to |
1813 | implement this functionality, due to the requirement of having a file |
2057 | implement this functionality, due to the requirement of having a file |
1814 | descriptor open on the object at all times, and detecting renames, unlinks |
2058 | descriptor open on the object at all times, and detecting renames, unlinks |
1815 | etc. is difficult. |
2059 | etc. is difficult. |
1816 | |
2060 | |
|
|
2061 | =head3 C<stat ()> is a synchronous operation |
|
|
2062 | |
|
|
2063 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2064 | the process. The exception are C<ev_stat> watchers - those call C<stat |
|
|
2065 | ()>, which is a synchronous operation. |
|
|
2066 | |
|
|
2067 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2068 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2069 | as the path data is usually in memory already (except when starting the |
|
|
2070 | watcher). |
|
|
2071 | |
|
|
2072 | For networked file systems, calling C<stat ()> can block an indefinite |
|
|
2073 | time due to network issues, and even under good conditions, a stat call |
|
|
2074 | often takes multiple milliseconds. |
|
|
2075 | |
|
|
2076 | Therefore, it is best to avoid using C<ev_stat> watchers on networked |
|
|
2077 | paths, although this is fully supported by libev. |
|
|
2078 | |
1817 | =head3 The special problem of stat time resolution |
2079 | =head3 The special problem of stat time resolution |
1818 | |
2080 | |
1819 | The C<stat ()> system call only supports full-second resolution portably, and |
2081 | The C<stat ()> system call only supports full-second resolution portably, |
1820 | even on systems where the resolution is higher, most file systems still |
2082 | and even on systems where the resolution is higher, most file systems |
1821 | only support whole seconds. |
2083 | still only support whole seconds. |
1822 | |
2084 | |
1823 | That means that, if the time is the only thing that changes, you can |
2085 | That means that, if the time is the only thing that changes, you can |
1824 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2086 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1825 | calls your callback, which does something. When there is another update |
2087 | calls your callback, which does something. When there is another update |
1826 | within the same second, C<ev_stat> will be unable to detect unless the |
2088 | within the same second, C<ev_stat> will be unable to detect unless the |
… | |
… | |
1969 | |
2231 | |
1970 | =head3 Watcher-Specific Functions and Data Members |
2232 | =head3 Watcher-Specific Functions and Data Members |
1971 | |
2233 | |
1972 | =over 4 |
2234 | =over 4 |
1973 | |
2235 | |
1974 | =item ev_idle_init (ev_signal *, callback) |
2236 | =item ev_idle_init (ev_idle *, callback) |
1975 | |
2237 | |
1976 | Initialises and configures the idle watcher - it has no parameters of any |
2238 | Initialises and configures the idle watcher - it has no parameters of any |
1977 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2239 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1978 | believe me. |
2240 | believe me. |
1979 | |
2241 | |
… | |
… | |
1983 | |
2245 | |
1984 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
2246 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1985 | callback, free it. Also, use no error checking, as usual. |
2247 | callback, free it. Also, use no error checking, as usual. |
1986 | |
2248 | |
1987 | static void |
2249 | static void |
1988 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2250 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1989 | { |
2251 | { |
1990 | free (w); |
2252 | free (w); |
1991 | // now do something you wanted to do when the program has |
2253 | // now do something you wanted to do when the program has |
1992 | // no longer anything immediate to do. |
2254 | // no longer anything immediate to do. |
1993 | } |
2255 | } |
1994 | |
2256 | |
1995 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2257 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1996 | ev_idle_init (idle_watcher, idle_cb); |
2258 | ev_idle_init (idle_watcher, idle_cb); |
1997 | ev_idle_start (loop, idle_cb); |
2259 | ev_idle_start (loop, idle_cb); |
1998 | |
2260 | |
1999 | |
2261 | |
2000 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2262 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
… | |
… | |
2081 | |
2343 | |
2082 | static ev_io iow [nfd]; |
2344 | static ev_io iow [nfd]; |
2083 | static ev_timer tw; |
2345 | static ev_timer tw; |
2084 | |
2346 | |
2085 | static void |
2347 | static void |
2086 | io_cb (ev_loop *loop, ev_io *w, int revents) |
2348 | io_cb (struct ev_loop *loop, ev_io *w, int revents) |
2087 | { |
2349 | { |
2088 | } |
2350 | } |
2089 | |
2351 | |
2090 | // create io watchers for each fd and a timer before blocking |
2352 | // create io watchers for each fd and a timer before blocking |
2091 | static void |
2353 | static void |
2092 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2354 | adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
2093 | { |
2355 | { |
2094 | int timeout = 3600000; |
2356 | int timeout = 3600000; |
2095 | struct pollfd fds [nfd]; |
2357 | struct pollfd fds [nfd]; |
2096 | // actual code will need to loop here and realloc etc. |
2358 | // actual code will need to loop here and realloc etc. |
2097 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2359 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
… | |
… | |
2112 | } |
2374 | } |
2113 | } |
2375 | } |
2114 | |
2376 | |
2115 | // stop all watchers after blocking |
2377 | // stop all watchers after blocking |
2116 | static void |
2378 | static void |
2117 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2379 | adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
2118 | { |
2380 | { |
2119 | ev_timer_stop (loop, &tw); |
2381 | ev_timer_stop (loop, &tw); |
2120 | |
2382 | |
2121 | for (int i = 0; i < nfd; ++i) |
2383 | for (int i = 0; i < nfd; ++i) |
2122 | { |
2384 | { |
… | |
… | |
2218 | some fds have to be watched and handled very quickly (with low latency), |
2480 | some fds have to be watched and handled very quickly (with low latency), |
2219 | and even priorities and idle watchers might have too much overhead. In |
2481 | and even priorities and idle watchers might have too much overhead. In |
2220 | this case you would put all the high priority stuff in one loop and all |
2482 | this case you would put all the high priority stuff in one loop and all |
2221 | the rest in a second one, and embed the second one in the first. |
2483 | the rest in a second one, and embed the second one in the first. |
2222 | |
2484 | |
2223 | As long as the watcher is active, the callback will be invoked every time |
2485 | As long as the watcher is active, the callback will be invoked every |
2224 | there might be events pending in the embedded loop. The callback must then |
2486 | time there might be events pending in the embedded loop. The callback |
2225 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2487 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2226 | their callbacks (you could also start an idle watcher to give the embedded |
2488 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2227 | loop strictly lower priority for example). You can also set the callback |
2489 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2228 | to C<0>, in which case the embed watcher will automatically execute the |
2490 | to give the embedded loop strictly lower priority for example). |
2229 | embedded loop sweep. |
|
|
2230 | |
2491 | |
2231 | As long as the watcher is started it will automatically handle events. The |
2492 | You can also set the callback to C<0>, in which case the embed watcher |
2232 | callback will be invoked whenever some events have been handled. You can |
2493 | will automatically execute the embedded loop sweep whenever necessary. |
2233 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2234 | interested in that. |
|
|
2235 | |
2494 | |
2236 | Also, there have not currently been made special provisions for forking: |
2495 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2237 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2496 | is active, i.e., the embedded loop will automatically be forked when the |
2238 | but you will also have to stop and restart any C<ev_embed> watchers |
2497 | embedding loop forks. In other cases, the user is responsible for calling |
2239 | yourself - but you can use a fork watcher to handle this automatically, |
2498 | C<ev_loop_fork> on the embedded loop. |
2240 | and future versions of libev might do just that. |
|
|
2241 | |
2499 | |
2242 | Unfortunately, not all backends are embeddable: only the ones returned by |
2500 | Unfortunately, not all backends are embeddable: only the ones returned by |
2243 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2501 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2244 | portable one. |
2502 | portable one. |
2245 | |
2503 | |
… | |
… | |
2290 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2548 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2291 | used). |
2549 | used). |
2292 | |
2550 | |
2293 | struct ev_loop *loop_hi = ev_default_init (0); |
2551 | struct ev_loop *loop_hi = ev_default_init (0); |
2294 | struct ev_loop *loop_lo = 0; |
2552 | struct ev_loop *loop_lo = 0; |
2295 | struct ev_embed embed; |
2553 | ev_embed embed; |
2296 | |
2554 | |
2297 | // see if there is a chance of getting one that works |
2555 | // see if there is a chance of getting one that works |
2298 | // (remember that a flags value of 0 means autodetection) |
2556 | // (remember that a flags value of 0 means autodetection) |
2299 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2557 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2300 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2558 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
… | |
… | |
2314 | kqueue implementation). Store the kqueue/socket-only event loop in |
2572 | kqueue implementation). Store the kqueue/socket-only event loop in |
2315 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2573 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2316 | |
2574 | |
2317 | struct ev_loop *loop = ev_default_init (0); |
2575 | struct ev_loop *loop = ev_default_init (0); |
2318 | struct ev_loop *loop_socket = 0; |
2576 | struct ev_loop *loop_socket = 0; |
2319 | struct ev_embed embed; |
2577 | ev_embed embed; |
2320 | |
2578 | |
2321 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2579 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2322 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2580 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2323 | { |
2581 | { |
2324 | ev_embed_init (&embed, 0, loop_socket); |
2582 | ev_embed_init (&embed, 0, loop_socket); |
… | |
… | |
2465 | =over 4 |
2723 | =over 4 |
2466 | |
2724 | |
2467 | =item ev_async_init (ev_async *, callback) |
2725 | =item ev_async_init (ev_async *, callback) |
2468 | |
2726 | |
2469 | Initialises and configures the async watcher - it has no parameters of any |
2727 | Initialises and configures the async watcher - it has no parameters of any |
2470 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2728 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2471 | trust me. |
2729 | trust me. |
2472 | |
2730 | |
2473 | =item ev_async_send (loop, ev_async *) |
2731 | =item ev_async_send (loop, ev_async *) |
2474 | |
2732 | |
2475 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2733 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2476 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2734 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2477 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2735 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2478 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2736 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2479 | section below on what exactly this means). |
2737 | section below on what exactly this means). |
2480 | |
2738 | |
|
|
2739 | Note that, as with other watchers in libev, multiple events might get |
|
|
2740 | compressed into a single callback invocation (another way to look at this |
|
|
2741 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
|
|
2742 | reset when the event loop detects that). |
|
|
2743 | |
2481 | This call incurs the overhead of a system call only once per loop iteration, |
2744 | This call incurs the overhead of a system call only once per event loop |
2482 | so while the overhead might be noticeable, it doesn't apply to repeated |
2745 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2483 | calls to C<ev_async_send>. |
2746 | repeated calls to C<ev_async_send> for the same event loop. |
2484 | |
2747 | |
2485 | =item bool = ev_async_pending (ev_async *) |
2748 | =item bool = ev_async_pending (ev_async *) |
2486 | |
2749 | |
2487 | Returns a non-zero value when C<ev_async_send> has been called on the |
2750 | Returns a non-zero value when C<ev_async_send> has been called on the |
2488 | watcher but the event has not yet been processed (or even noted) by the |
2751 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
2491 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2754 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2492 | the loop iterates next and checks for the watcher to have become active, |
2755 | the loop iterates next and checks for the watcher to have become active, |
2493 | it will reset the flag again. C<ev_async_pending> can be used to very |
2756 | it will reset the flag again. C<ev_async_pending> can be used to very |
2494 | quickly check whether invoking the loop might be a good idea. |
2757 | quickly check whether invoking the loop might be a good idea. |
2495 | |
2758 | |
2496 | Not that this does I<not> check whether the watcher itself is pending, only |
2759 | Not that this does I<not> check whether the watcher itself is pending, |
2497 | whether it has been requested to make this watcher pending. |
2760 | only whether it has been requested to make this watcher pending: there |
|
|
2761 | is a time window between the event loop checking and resetting the async |
|
|
2762 | notification, and the callback being invoked. |
2498 | |
2763 | |
2499 | =back |
2764 | =back |
2500 | |
2765 | |
2501 | |
2766 | |
2502 | =head1 OTHER FUNCTIONS |
2767 | =head1 OTHER FUNCTIONS |
… | |
… | |
2538 | /* doh, nothing entered */; |
2803 | /* doh, nothing entered */; |
2539 | } |
2804 | } |
2540 | |
2805 | |
2541 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2806 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2542 | |
2807 | |
2543 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2808 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
2544 | |
2809 | |
2545 | Feeds the given event set into the event loop, as if the specified event |
2810 | Feeds the given event set into the event loop, as if the specified event |
2546 | had happened for the specified watcher (which must be a pointer to an |
2811 | had happened for the specified watcher (which must be a pointer to an |
2547 | initialised but not necessarily started event watcher). |
2812 | initialised but not necessarily started event watcher). |
2548 | |
2813 | |
2549 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
2814 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
2550 | |
2815 | |
2551 | Feed an event on the given fd, as if a file descriptor backend detected |
2816 | Feed an event on the given fd, as if a file descriptor backend detected |
2552 | the given events it. |
2817 | the given events it. |
2553 | |
2818 | |
2554 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2819 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
2555 | |
2820 | |
2556 | Feed an event as if the given signal occurred (C<loop> must be the default |
2821 | Feed an event as if the given signal occurred (C<loop> must be the default |
2557 | loop!). |
2822 | loop!). |
2558 | |
2823 | |
2559 | =back |
2824 | =back |
… | |
… | |
2680 | } |
2945 | } |
2681 | |
2946 | |
2682 | myclass obj; |
2947 | myclass obj; |
2683 | ev::io iow; |
2948 | ev::io iow; |
2684 | iow.set <myclass, &myclass::io_cb> (&obj); |
2949 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2950 | |
|
|
2951 | =item w->set (object *) |
|
|
2952 | |
|
|
2953 | This is an B<experimental> feature that might go away in a future version. |
|
|
2954 | |
|
|
2955 | This is a variation of a method callback - leaving out the method to call |
|
|
2956 | will default the method to C<operator ()>, which makes it possible to use |
|
|
2957 | functor objects without having to manually specify the C<operator ()> all |
|
|
2958 | the time. Incidentally, you can then also leave out the template argument |
|
|
2959 | list. |
|
|
2960 | |
|
|
2961 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
2962 | int revents)>. |
|
|
2963 | |
|
|
2964 | See the method-C<set> above for more details. |
|
|
2965 | |
|
|
2966 | Example: use a functor object as callback. |
|
|
2967 | |
|
|
2968 | struct myfunctor |
|
|
2969 | { |
|
|
2970 | void operator() (ev::io &w, int revents) |
|
|
2971 | { |
|
|
2972 | ... |
|
|
2973 | } |
|
|
2974 | } |
|
|
2975 | |
|
|
2976 | myfunctor f; |
|
|
2977 | |
|
|
2978 | ev::io w; |
|
|
2979 | w.set (&f); |
2685 | |
2980 | |
2686 | =item w->set<function> (void *data = 0) |
2981 | =item w->set<function> (void *data = 0) |
2687 | |
2982 | |
2688 | Also sets a callback, but uses a static method or plain function as |
2983 | Also sets a callback, but uses a static method or plain function as |
2689 | callback. The optional C<data> argument will be stored in the watcher's |
2984 | callback. The optional C<data> argument will be stored in the watcher's |
… | |
… | |
2776 | L<http://software.schmorp.de/pkg/EV>. |
3071 | L<http://software.schmorp.de/pkg/EV>. |
2777 | |
3072 | |
2778 | =item Python |
3073 | =item Python |
2779 | |
3074 | |
2780 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
3075 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
2781 | seems to be quite complete and well-documented. Note, however, that the |
3076 | seems to be quite complete and well-documented. |
2782 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2783 | for everybody else, and therefore, should never be applied in an installed |
|
|
2784 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2785 | libev). |
|
|
2786 | |
3077 | |
2787 | =item Ruby |
3078 | =item Ruby |
2788 | |
3079 | |
2789 | Tony Arcieri has written a ruby extension that offers access to a subset |
3080 | Tony Arcieri has written a ruby extension that offers access to a subset |
2790 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3081 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2791 | more on top of it. It can be found via gem servers. Its homepage is at |
3082 | more on top of it. It can be found via gem servers. Its homepage is at |
2792 | L<http://rev.rubyforge.org/>. |
3083 | L<http://rev.rubyforge.org/>. |
2793 | |
3084 | |
|
|
3085 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3086 | makes rev work even on mingw. |
|
|
3087 | |
|
|
3088 | =item Haskell |
|
|
3089 | |
|
|
3090 | A haskell binding to libev is available at |
|
|
3091 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
|
|
3092 | |
2794 | =item D |
3093 | =item D |
2795 | |
3094 | |
2796 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3095 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2797 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3096 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
|
|
3097 | |
|
|
3098 | =item Ocaml |
|
|
3099 | |
|
|
3100 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3101 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
2798 | |
3102 | |
2799 | =back |
3103 | =back |
2800 | |
3104 | |
2801 | |
3105 | |
2802 | =head1 MACRO MAGIC |
3106 | =head1 MACRO MAGIC |
… | |
… | |
2903 | |
3207 | |
2904 | #define EV_STANDALONE 1 |
3208 | #define EV_STANDALONE 1 |
2905 | #include "ev.h" |
3209 | #include "ev.h" |
2906 | |
3210 | |
2907 | Both header files and implementation files can be compiled with a C++ |
3211 | Both header files and implementation files can be compiled with a C++ |
2908 | compiler (at least, thats a stated goal, and breakage will be treated |
3212 | compiler (at least, that's a stated goal, and breakage will be treated |
2909 | as a bug). |
3213 | as a bug). |
2910 | |
3214 | |
2911 | You need the following files in your source tree, or in a directory |
3215 | You need the following files in your source tree, or in a directory |
2912 | in your include path (e.g. in libev/ when using -Ilibev): |
3216 | in your include path (e.g. in libev/ when using -Ilibev): |
2913 | |
3217 | |
… | |
… | |
2969 | keeps libev from including F<config.h>, and it also defines dummy |
3273 | keeps libev from including F<config.h>, and it also defines dummy |
2970 | implementations for some libevent functions (such as logging, which is not |
3274 | implementations for some libevent functions (such as logging, which is not |
2971 | supported). It will also not define any of the structs usually found in |
3275 | supported). It will also not define any of the structs usually found in |
2972 | F<event.h> that are not directly supported by the libev core alone. |
3276 | F<event.h> that are not directly supported by the libev core alone. |
2973 | |
3277 | |
|
|
3278 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3279 | configuration, but has to be more conservative. |
|
|
3280 | |
2974 | =item EV_USE_MONOTONIC |
3281 | =item EV_USE_MONOTONIC |
2975 | |
3282 | |
2976 | If defined to be C<1>, libev will try to detect the availability of the |
3283 | If defined to be C<1>, libev will try to detect the availability of the |
2977 | monotonic clock option at both compile time and runtime. Otherwise no use |
3284 | monotonic clock option at both compile time and runtime. Otherwise no |
2978 | of the monotonic clock option will be attempted. If you enable this, you |
3285 | use of the monotonic clock option will be attempted. If you enable this, |
2979 | usually have to link against librt or something similar. Enabling it when |
3286 | you usually have to link against librt or something similar. Enabling it |
2980 | the functionality isn't available is safe, though, although you have |
3287 | when the functionality isn't available is safe, though, although you have |
2981 | to make sure you link against any libraries where the C<clock_gettime> |
3288 | to make sure you link against any libraries where the C<clock_gettime> |
2982 | function is hiding in (often F<-lrt>). |
3289 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
2983 | |
3290 | |
2984 | =item EV_USE_REALTIME |
3291 | =item EV_USE_REALTIME |
2985 | |
3292 | |
2986 | If defined to be C<1>, libev will try to detect the availability of the |
3293 | If defined to be C<1>, libev will try to detect the availability of the |
2987 | real-time clock option at compile time (and assume its availability at |
3294 | real-time clock option at compile time (and assume its availability |
2988 | runtime if successful). Otherwise no use of the real-time clock option will |
3295 | at runtime if successful). Otherwise no use of the real-time clock |
2989 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3296 | option will be attempted. This effectively replaces C<gettimeofday> |
2990 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3297 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
2991 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3298 | correctness. See the note about libraries in the description of |
|
|
3299 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3300 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3301 | |
|
|
3302 | =item EV_USE_CLOCK_SYSCALL |
|
|
3303 | |
|
|
3304 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3305 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3306 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3307 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3308 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3309 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3310 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3311 | higher, as it simplifies linking (no need for C<-lrt>). |
2992 | |
3312 | |
2993 | =item EV_USE_NANOSLEEP |
3313 | =item EV_USE_NANOSLEEP |
2994 | |
3314 | |
2995 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3315 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2996 | and will use it for delays. Otherwise it will use C<select ()>. |
3316 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3012 | |
3332 | |
3013 | =item EV_SELECT_USE_FD_SET |
3333 | =item EV_SELECT_USE_FD_SET |
3014 | |
3334 | |
3015 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3335 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3016 | structure. This is useful if libev doesn't compile due to a missing |
3336 | structure. This is useful if libev doesn't compile due to a missing |
3017 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3337 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3018 | exotic systems. This usually limits the range of file descriptors to some |
3338 | on exotic systems. This usually limits the range of file descriptors to |
3019 | low limit such as 1024 or might have other limitations (winsocket only |
3339 | some low limit such as 1024 or might have other limitations (winsocket |
3020 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3340 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3021 | influence the size of the C<fd_set> used. |
3341 | configures the maximum size of the C<fd_set>. |
3022 | |
3342 | |
3023 | =item EV_SELECT_IS_WINSOCKET |
3343 | =item EV_SELECT_IS_WINSOCKET |
3024 | |
3344 | |
3025 | When defined to C<1>, the select backend will assume that |
3345 | When defined to C<1>, the select backend will assume that |
3026 | select/socket/connect etc. don't understand file descriptors but |
3346 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3385 | loop, as long as you don't confuse yourself). The only exception is that |
3705 | loop, as long as you don't confuse yourself). The only exception is that |
3386 | you must not do this from C<ev_periodic> reschedule callbacks. |
3706 | you must not do this from C<ev_periodic> reschedule callbacks. |
3387 | |
3707 | |
3388 | Care has been taken to ensure that libev does not keep local state inside |
3708 | Care has been taken to ensure that libev does not keep local state inside |
3389 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3709 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3390 | they do not clal any callbacks. |
3710 | they do not call any callbacks. |
3391 | |
3711 | |
3392 | =head2 COMPILER WARNINGS |
3712 | =head2 COMPILER WARNINGS |
3393 | |
3713 | |
3394 | Depending on your compiler and compiler settings, you might get no or a |
3714 | Depending on your compiler and compiler settings, you might get no or a |
3395 | lot of warnings when compiling libev code. Some people are apparently |
3715 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3429 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3749 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3430 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3750 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3431 | ==2274== still reachable: 256 bytes in 1 blocks. |
3751 | ==2274== still reachable: 256 bytes in 1 blocks. |
3432 | |
3752 | |
3433 | Then there is no memory leak, just as memory accounted to global variables |
3753 | Then there is no memory leak, just as memory accounted to global variables |
3434 | is not a memleak - the memory is still being refernced, and didn't leak. |
3754 | is not a memleak - the memory is still being referenced, and didn't leak. |
3435 | |
3755 | |
3436 | Similarly, under some circumstances, valgrind might report kernel bugs |
3756 | Similarly, under some circumstances, valgrind might report kernel bugs |
3437 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3757 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3438 | although an acceptable workaround has been found here), or it might be |
3758 | although an acceptable workaround has been found here), or it might be |
3439 | confused. |
3759 | confused. |
… | |
… | |
3677 | =back |
3997 | =back |
3678 | |
3998 | |
3679 | |
3999 | |
3680 | =head1 AUTHOR |
4000 | =head1 AUTHOR |
3681 | |
4001 | |
3682 | Marc Lehmann <libev@schmorp.de>. |
4002 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3683 | |
4003 | |