… | |
… | |
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 | |
|
|
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 |
|
|
397 | so on. The biggest issue is fork races, however - if a program forks then |
|
|
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 |
|
|
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 |
|
|
405 | even remove them from the set) than registered in the set (especially |
|
|
406 | on SMP systems). Libev tries to counter these spurious notifications by |
|
|
407 | employing an additional generation counter and comparing that against the |
|
|
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 |
|
|
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>). |
… | |
… | |
631 | the loop. |
658 | the loop. |
632 | |
659 | |
633 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
660 | 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 |
661 | 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 |
662 | 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 |
663 | 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 |
664 | user-registered callback will be called), and will return after one |
638 | iteration of the loop. |
665 | iteration of the loop. |
639 | |
666 | |
640 | This is useful if you are waiting for some external event in conjunction |
667 | 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 |
668 | with something not expressible using other libev watchers (i.e. "roll your |
… | |
… | |
685 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
712 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
686 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
713 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
687 | |
714 | |
688 | This "unloop state" will be cleared when entering C<ev_loop> again. |
715 | This "unloop state" will be cleared when entering C<ev_loop> again. |
689 | |
716 | |
|
|
717 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
|
|
718 | |
690 | =item ev_ref (loop) |
719 | =item ev_ref (loop) |
691 | |
720 | |
692 | =item ev_unref (loop) |
721 | =item ev_unref (loop) |
693 | |
722 | |
694 | Ref/unref can be used to add or remove a reference count on the event |
723 | Ref/unref can be used to add or remove a reference count on the event |
… | |
… | |
708 | respectively). |
737 | respectively). |
709 | |
738 | |
710 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
739 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
711 | running when nothing else is active. |
740 | running when nothing else is active. |
712 | |
741 | |
713 | struct ev_signal exitsig; |
742 | ev_signal exitsig; |
714 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
743 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
715 | ev_signal_start (loop, &exitsig); |
744 | ev_signal_start (loop, &exitsig); |
716 | evf_unref (loop); |
745 | evf_unref (loop); |
717 | |
746 | |
718 | Example: For some weird reason, unregister the above signal handler again. |
747 | Example: For some weird reason, unregister the above signal handler again. |
… | |
… | |
766 | they fire on, say, one-second boundaries only. |
795 | they fire on, say, one-second boundaries only. |
767 | |
796 | |
768 | =item ev_loop_verify (loop) |
797 | =item ev_loop_verify (loop) |
769 | |
798 | |
770 | This function only does something when C<EV_VERIFY> support has been |
799 | This function only does something when C<EV_VERIFY> support has been |
771 | compiled in. which is the default for non-minimal builds. It tries to go |
800 | compiled in, which is the default for non-minimal builds. It tries to go |
772 | through all internal structures and checks them for validity. If anything |
801 | through all internal structures and checks them for validity. If anything |
773 | is found to be inconsistent, it will print an error message to standard |
802 | is found to be inconsistent, it will print an error message to standard |
774 | error and call C<abort ()>. |
803 | error and call C<abort ()>. |
775 | |
804 | |
776 | This can be used to catch bugs inside libev itself: under normal |
805 | This can be used to catch bugs inside libev itself: under normal |
… | |
… | |
780 | =back |
809 | =back |
781 | |
810 | |
782 | |
811 | |
783 | =head1 ANATOMY OF A WATCHER |
812 | =head1 ANATOMY OF A WATCHER |
784 | |
813 | |
|
|
814 | In the following description, uppercase C<TYPE> in names stands for the |
|
|
815 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
|
|
816 | watchers and C<ev_io_start> for I/O watchers. |
|
|
817 | |
785 | A watcher is a structure that you create and register to record your |
818 | A watcher is a structure that you create and register to record your |
786 | interest in some event. For instance, if you want to wait for STDIN to |
819 | interest in some event. For instance, if you want to wait for STDIN to |
787 | become readable, you would create an C<ev_io> watcher for that: |
820 | become readable, you would create an C<ev_io> watcher for that: |
788 | |
821 | |
789 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
822 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
790 | { |
823 | { |
791 | ev_io_stop (w); |
824 | ev_io_stop (w); |
792 | ev_unloop (loop, EVUNLOOP_ALL); |
825 | ev_unloop (loop, EVUNLOOP_ALL); |
793 | } |
826 | } |
794 | |
827 | |
795 | struct ev_loop *loop = ev_default_loop (0); |
828 | struct ev_loop *loop = ev_default_loop (0); |
|
|
829 | |
796 | struct ev_io stdin_watcher; |
830 | ev_io stdin_watcher; |
|
|
831 | |
797 | ev_init (&stdin_watcher, my_cb); |
832 | ev_init (&stdin_watcher, my_cb); |
798 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
833 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
799 | ev_io_start (loop, &stdin_watcher); |
834 | ev_io_start (loop, &stdin_watcher); |
|
|
835 | |
800 | ev_loop (loop, 0); |
836 | ev_loop (loop, 0); |
801 | |
837 | |
802 | As you can see, you are responsible for allocating the memory for your |
838 | As you can see, you are responsible for allocating the memory for your |
803 | watcher structures (and it is usually a bad idea to do this on the stack, |
839 | watcher structures (and it is I<usually> a bad idea to do this on the |
804 | although this can sometimes be quite valid). |
840 | stack). |
|
|
841 | |
|
|
842 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
|
|
843 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
805 | |
844 | |
806 | Each watcher structure must be initialised by a call to C<ev_init |
845 | Each watcher structure must be initialised by a call to C<ev_init |
807 | (watcher *, callback)>, which expects a callback to be provided. This |
846 | (watcher *, callback)>, which expects a callback to be provided. This |
808 | callback gets invoked each time the event occurs (or, in the case of I/O |
847 | callback gets invoked each time the event occurs (or, in the case of I/O |
809 | watchers, each time the event loop detects that the file descriptor given |
848 | watchers, each time the event loop detects that the file descriptor given |
810 | is readable and/or writable). |
849 | is readable and/or writable). |
811 | |
850 | |
812 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
851 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
813 | with arguments specific to this watcher type. There is also a macro |
852 | macro to configure it, with arguments specific to the watcher type. There |
814 | to combine initialisation and setting in one call: C<< ev_<type>_init |
853 | is also a macro to combine initialisation and setting in one call: C<< |
815 | (watcher *, callback, ...) >>. |
854 | ev_TYPE_init (watcher *, callback, ...) >>. |
816 | |
855 | |
817 | To make the watcher actually watch out for events, you have to start it |
856 | To make the watcher actually watch out for events, you have to start it |
818 | with a watcher-specific start function (C<< ev_<type>_start (loop, watcher |
857 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
819 | *) >>), and you can stop watching for events at any time by calling the |
858 | *) >>), and you can stop watching for events at any time by calling the |
820 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
859 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
821 | |
860 | |
822 | As long as your watcher is active (has been started but not stopped) you |
861 | As long as your watcher is active (has been started but not stopped) you |
823 | must not touch the values stored in it. Most specifically you must never |
862 | must not touch the values stored in it. Most specifically you must never |
824 | reinitialise it or call its C<set> macro. |
863 | reinitialise it or call its C<ev_TYPE_set> macro. |
825 | |
864 | |
826 | Each and every callback receives the event loop pointer as first, the |
865 | Each and every callback receives the event loop pointer as first, the |
827 | registered watcher structure as second, and a bitset of received events as |
866 | registered watcher structure as second, and a bitset of received events as |
828 | third argument. |
867 | third argument. |
829 | |
868 | |
… | |
… | |
892 | =item C<EV_ERROR> |
931 | =item C<EV_ERROR> |
893 | |
932 | |
894 | An unspecified error has occurred, the watcher has been stopped. This might |
933 | An unspecified error has occurred, the watcher has been stopped. This might |
895 | happen because the watcher could not be properly started because libev |
934 | happen because the watcher could not be properly started because libev |
896 | ran out of memory, a file descriptor was found to be closed or any other |
935 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
936 | problem. Libev considers these application bugs. |
|
|
937 | |
897 | problem. You best act on it by reporting the problem and somehow coping |
938 | You best act on it by reporting the problem and somehow coping with the |
898 | with the watcher being stopped. |
939 | watcher being stopped. Note that well-written programs should not receive |
|
|
940 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
941 | bug in your program. |
899 | |
942 | |
900 | Libev will usually signal a few "dummy" events together with an error, for |
943 | Libev will usually signal a few "dummy" events together with an error, for |
901 | example it might indicate that a fd is readable or writable, and if your |
944 | example it might indicate that a fd is readable or writable, and if your |
902 | callbacks is well-written it can just attempt the operation and cope with |
945 | callbacks is well-written it can just attempt the operation and cope with |
903 | the error from read() or write(). This will not work in multi-threaded |
946 | the error from read() or write(). This will not work in multi-threaded |
… | |
… | |
906 | |
949 | |
907 | =back |
950 | =back |
908 | |
951 | |
909 | =head2 GENERIC WATCHER FUNCTIONS |
952 | =head2 GENERIC WATCHER FUNCTIONS |
910 | |
953 | |
911 | In the following description, C<TYPE> stands for the watcher type, |
|
|
912 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
913 | |
|
|
914 | =over 4 |
954 | =over 4 |
915 | |
955 | |
916 | =item C<ev_init> (ev_TYPE *watcher, callback) |
956 | =item C<ev_init> (ev_TYPE *watcher, callback) |
917 | |
957 | |
918 | This macro initialises the generic portion of a watcher. The contents |
958 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
923 | which rolls both calls into one. |
963 | which rolls both calls into one. |
924 | |
964 | |
925 | You can reinitialise a watcher at any time as long as it has been stopped |
965 | You can reinitialise a watcher at any time as long as it has been stopped |
926 | (or never started) and there are no pending events outstanding. |
966 | (or never started) and there are no pending events outstanding. |
927 | |
967 | |
928 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
968 | The callback is always of type C<void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
929 | int revents)>. |
969 | int revents)>. |
930 | |
970 | |
931 | Example: Initialise an C<ev_io> watcher in two steps. |
971 | Example: Initialise an C<ev_io> watcher in two steps. |
932 | |
972 | |
933 | ev_io w; |
973 | ev_io w; |
… | |
… | |
967 | |
1007 | |
968 | ev_io_start (EV_DEFAULT_UC, &w); |
1008 | ev_io_start (EV_DEFAULT_UC, &w); |
969 | |
1009 | |
970 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1010 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
971 | |
1011 | |
972 | Stops the given watcher again (if active) and clears the pending |
1012 | Stops the given watcher if active, and clears the pending status (whether |
|
|
1013 | the watcher was active or not). |
|
|
1014 | |
973 | status. It is possible that stopped watchers are pending (for example, |
1015 | It is possible that stopped watchers are pending - for example, |
974 | non-repeating timers are being stopped when they become pending), but |
1016 | non-repeating timers are being stopped when they become pending - but |
975 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
1017 | calling C<ev_TYPE_stop> ensures that the watcher is neither active nor |
976 | you want to free or reuse the memory used by the watcher it is therefore a |
1018 | pending. If you want to free or reuse the memory used by the watcher it is |
977 | good idea to always call its C<ev_TYPE_stop> function. |
1019 | therefore a good idea to always call its C<ev_TYPE_stop> function. |
978 | |
1020 | |
979 | =item bool ev_is_active (ev_TYPE *watcher) |
1021 | =item bool ev_is_active (ev_TYPE *watcher) |
980 | |
1022 | |
981 | Returns a true value iff the watcher is active (i.e. it has been started |
1023 | Returns a true value iff the watcher is active (i.e. it has been started |
982 | and not yet been stopped). As long as a watcher is active you must not modify |
1024 | and not yet been stopped). As long as a watcher is active you must not modify |
… | |
… | |
1024 | The default priority used by watchers when no priority has been set is |
1066 | The default priority used by watchers when no priority has been set is |
1025 | always C<0>, which is supposed to not be too high and not be too low :). |
1067 | always C<0>, which is supposed to not be too high and not be too low :). |
1026 | |
1068 | |
1027 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1069 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1028 | fine, as long as you do not mind that the priority value you query might |
1070 | fine, as long as you do not mind that the priority value you query might |
1029 | or might not have been adjusted to be within valid range. |
1071 | or might not have been clamped to the valid range. |
1030 | |
1072 | |
1031 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1073 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1032 | |
1074 | |
1033 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1075 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1034 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1076 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1056 | member, you can also "subclass" the watcher type and provide your own |
1098 | member, you can also "subclass" the watcher type and provide your own |
1057 | data: |
1099 | data: |
1058 | |
1100 | |
1059 | struct my_io |
1101 | struct my_io |
1060 | { |
1102 | { |
1061 | struct ev_io io; |
1103 | ev_io io; |
1062 | int otherfd; |
1104 | int otherfd; |
1063 | void *somedata; |
1105 | void *somedata; |
1064 | struct whatever *mostinteresting; |
1106 | struct whatever *mostinteresting; |
1065 | }; |
1107 | }; |
1066 | |
1108 | |
… | |
… | |
1069 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1111 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
1070 | |
1112 | |
1071 | And since your callback will be called with a pointer to the watcher, you |
1113 | And since your callback will be called with a pointer to the watcher, you |
1072 | can cast it back to your own type: |
1114 | can cast it back to your own type: |
1073 | |
1115 | |
1074 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1116 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1075 | { |
1117 | { |
1076 | struct my_io *w = (struct my_io *)w_; |
1118 | struct my_io *w = (struct my_io *)w_; |
1077 | ... |
1119 | ... |
1078 | } |
1120 | } |
1079 | |
1121 | |
… | |
… | |
1097 | programmers): |
1139 | programmers): |
1098 | |
1140 | |
1099 | #include <stddef.h> |
1141 | #include <stddef.h> |
1100 | |
1142 | |
1101 | static void |
1143 | static void |
1102 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1144 | t1_cb (EV_P_ ev_timer *w, int revents) |
1103 | { |
1145 | { |
1104 | struct my_biggy big = (struct my_biggy * |
1146 | struct my_biggy big = (struct my_biggy * |
1105 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1147 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1106 | } |
1148 | } |
1107 | |
1149 | |
1108 | static void |
1150 | static void |
1109 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1151 | t2_cb (EV_P_ ev_timer *w, int revents) |
1110 | { |
1152 | { |
1111 | struct my_biggy big = (struct my_biggy * |
1153 | struct my_biggy big = (struct my_biggy * |
1112 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1154 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1113 | } |
1155 | } |
1114 | |
1156 | |
… | |
… | |
1249 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1291 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1250 | readable, but only once. Since it is likely line-buffered, you could |
1292 | readable, but only once. Since it is likely line-buffered, you could |
1251 | attempt to read a whole line in the callback. |
1293 | attempt to read a whole line in the callback. |
1252 | |
1294 | |
1253 | static void |
1295 | static void |
1254 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1296 | stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
1255 | { |
1297 | { |
1256 | ev_io_stop (loop, w); |
1298 | ev_io_stop (loop, w); |
1257 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1299 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1258 | } |
1300 | } |
1259 | |
1301 | |
1260 | ... |
1302 | ... |
1261 | struct ev_loop *loop = ev_default_init (0); |
1303 | struct ev_loop *loop = ev_default_init (0); |
1262 | struct ev_io stdin_readable; |
1304 | ev_io stdin_readable; |
1263 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1305 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1264 | ev_io_start (loop, &stdin_readable); |
1306 | ev_io_start (loop, &stdin_readable); |
1265 | ev_loop (loop, 0); |
1307 | ev_loop (loop, 0); |
1266 | |
1308 | |
1267 | |
1309 | |
… | |
… | |
1278 | |
1320 | |
1279 | The callback is guaranteed to be invoked only I<after> its timeout has |
1321 | The callback is guaranteed to be invoked only I<after> its timeout has |
1280 | passed, but if multiple timers become ready during the same loop iteration |
1322 | passed, but if multiple timers become ready during the same loop iteration |
1281 | then order of execution is undefined. |
1323 | then order of execution is undefined. |
1282 | |
1324 | |
|
|
1325 | =head3 Be smart about timeouts |
|
|
1326 | |
|
|
1327 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1328 | recovery. A typical example is an HTTP request - if the other side hangs, |
|
|
1329 | you want to raise some error after a while. |
|
|
1330 | |
|
|
1331 | What follows are some ways to handle this problem, from obvious and |
|
|
1332 | inefficient to smart and efficient. |
|
|
1333 | |
|
|
1334 | In the following, a 60 second activity timeout is assumed - a timeout that |
|
|
1335 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1336 | data or other life sign was received). |
|
|
1337 | |
|
|
1338 | =over 4 |
|
|
1339 | |
|
|
1340 | =item 1. Use a timer and stop, reinitialise and start it on activity. |
|
|
1341 | |
|
|
1342 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1343 | start the watcher: |
|
|
1344 | |
|
|
1345 | ev_timer_init (timer, callback, 60., 0.); |
|
|
1346 | ev_timer_start (loop, timer); |
|
|
1347 | |
|
|
1348 | Then, each time there is some activity, C<ev_timer_stop> it, initialise it |
|
|
1349 | and start it again: |
|
|
1350 | |
|
|
1351 | ev_timer_stop (loop, timer); |
|
|
1352 | ev_timer_set (timer, 60., 0.); |
|
|
1353 | ev_timer_start (loop, timer); |
|
|
1354 | |
|
|
1355 | This is relatively simple to implement, but means that each time there is |
|
|
1356 | some activity, libev will first have to remove the timer from its internal |
|
|
1357 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1358 | still not a constant-time operation. |
|
|
1359 | |
|
|
1360 | =item 2. Use a timer and re-start it with C<ev_timer_again> inactivity. |
|
|
1361 | |
|
|
1362 | This is the easiest way, and involves using C<ev_timer_again> instead of |
|
|
1363 | C<ev_timer_start>. |
|
|
1364 | |
|
|
1365 | To implement this, configure an C<ev_timer> with a C<repeat> value |
|
|
1366 | of C<60> and then call C<ev_timer_again> at start and each time you |
|
|
1367 | successfully read or write some data. If you go into an idle state where |
|
|
1368 | you do not expect data to travel on the socket, you can C<ev_timer_stop> |
|
|
1369 | the timer, and C<ev_timer_again> will automatically restart it if need be. |
|
|
1370 | |
|
|
1371 | That means you can ignore both the C<ev_timer_start> function and the |
|
|
1372 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
|
|
1373 | member and C<ev_timer_again>. |
|
|
1374 | |
|
|
1375 | At start: |
|
|
1376 | |
|
|
1377 | ev_timer_init (timer, callback); |
|
|
1378 | timer->repeat = 60.; |
|
|
1379 | ev_timer_again (loop, timer); |
|
|
1380 | |
|
|
1381 | Each time there is some activity: |
|
|
1382 | |
|
|
1383 | ev_timer_again (loop, timer); |
|
|
1384 | |
|
|
1385 | It is even possible to change the time-out on the fly, regardless of |
|
|
1386 | whether the watcher is active or not: |
|
|
1387 | |
|
|
1388 | timer->repeat = 30.; |
|
|
1389 | ev_timer_again (loop, timer); |
|
|
1390 | |
|
|
1391 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1392 | you want to modify its timeout value, as libev does not have to completely |
|
|
1393 | remove and re-insert the timer from/into its internal data structure. |
|
|
1394 | |
|
|
1395 | It is, however, even simpler than the "obvious" way to do it. |
|
|
1396 | |
|
|
1397 | =item 3. Let the timer time out, but then re-arm it as required. |
|
|
1398 | |
|
|
1399 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1400 | relatively long compared to the intervals between other activity - in |
|
|
1401 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1402 | associated activity resets. |
|
|
1403 | |
|
|
1404 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
|
|
1405 | but remember the time of last activity, and check for a real timeout only |
|
|
1406 | within the callback: |
|
|
1407 | |
|
|
1408 | ev_tstamp last_activity; // time of last activity |
|
|
1409 | |
|
|
1410 | static void |
|
|
1411 | callback (EV_P_ ev_timer *w, int revents) |
|
|
1412 | { |
|
|
1413 | ev_tstamp now = ev_now (EV_A); |
|
|
1414 | ev_tstamp timeout = last_activity + 60.; |
|
|
1415 | |
|
|
1416 | // if last_activity + 60. is older than now, we did time out |
|
|
1417 | if (timeout < now) |
|
|
1418 | { |
|
|
1419 | // timeout occured, take action |
|
|
1420 | } |
|
|
1421 | else |
|
|
1422 | { |
|
|
1423 | // callback was invoked, but there was some activity, re-arm |
|
|
1424 | // the watcher to fire in last_activity + 60, which is |
|
|
1425 | // guaranteed to be in the future, so "again" is positive: |
|
|
1426 | w->repeat = timeout - now; |
|
|
1427 | ev_timer_again (EV_A_ w); |
|
|
1428 | } |
|
|
1429 | } |
|
|
1430 | |
|
|
1431 | To summarise the callback: first calculate the real timeout (defined |
|
|
1432 | as "60 seconds after the last activity"), then check if that time has |
|
|
1433 | been reached, which means something I<did>, in fact, time out. Otherwise |
|
|
1434 | the callback was invoked too early (C<timeout> is in the future), so |
|
|
1435 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1436 | a timeout then. |
|
|
1437 | |
|
|
1438 | Note how C<ev_timer_again> is used, taking advantage of the |
|
|
1439 | C<ev_timer_again> optimisation when the timer is already running. |
|
|
1440 | |
|
|
1441 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1442 | minus half the average time between activity), but virtually no calls to |
|
|
1443 | libev to change the timeout. |
|
|
1444 | |
|
|
1445 | To start the timer, simply initialise the watcher and set C<last_activity> |
|
|
1446 | to the current time (meaning we just have some activity :), then call the |
|
|
1447 | callback, which will "do the right thing" and start the timer: |
|
|
1448 | |
|
|
1449 | ev_timer_init (timer, callback); |
|
|
1450 | last_activity = ev_now (loop); |
|
|
1451 | callback (loop, timer, EV_TIMEOUT); |
|
|
1452 | |
|
|
1453 | And when there is some activity, simply store the current time in |
|
|
1454 | C<last_activity>, no libev calls at all: |
|
|
1455 | |
|
|
1456 | last_actiivty = ev_now (loop); |
|
|
1457 | |
|
|
1458 | This technique is slightly more complex, but in most cases where the |
|
|
1459 | time-out is unlikely to be triggered, much more efficient. |
|
|
1460 | |
|
|
1461 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1462 | callback :) - just change the timeout and invoke the callback, which will |
|
|
1463 | fix things for you. |
|
|
1464 | |
|
|
1465 | =item 4. Wee, just use a double-linked list for your timeouts. |
|
|
1466 | |
|
|
1467 | If there is not one request, but many thousands (millions...), all |
|
|
1468 | employing some kind of timeout with the same timeout value, then one can |
|
|
1469 | do even better: |
|
|
1470 | |
|
|
1471 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1472 | at the I<end> of the list. |
|
|
1473 | |
|
|
1474 | Then use an C<ev_timer> to fire when the timeout at the I<beginning> of |
|
|
1475 | the list is expected to fire (for example, using the technique #3). |
|
|
1476 | |
|
|
1477 | When there is some activity, remove the timer from the list, recalculate |
|
|
1478 | the timeout, append it to the end of the list again, and make sure to |
|
|
1479 | update the C<ev_timer> if it was taken from the beginning of the list. |
|
|
1480 | |
|
|
1481 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1482 | starting, stopping and updating the timers, at the expense of a major |
|
|
1483 | complication, and having to use a constant timeout. The constant timeout |
|
|
1484 | ensures that the list stays sorted. |
|
|
1485 | |
|
|
1486 | =back |
|
|
1487 | |
|
|
1488 | So which method the best? |
|
|
1489 | |
|
|
1490 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1491 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1492 | better, and isn't very complicated either. In most case, choosing either |
|
|
1493 | one is fine, with #3 being better in typical situations. |
|
|
1494 | |
|
|
1495 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1496 | rather complicated, but extremely efficient, something that really pays |
|
|
1497 | off after the first million or so of active timers, i.e. it's usually |
|
|
1498 | overkill :) |
|
|
1499 | |
1283 | =head3 The special problem of time updates |
1500 | =head3 The special problem of time updates |
1284 | |
1501 | |
1285 | Establishing the current time is a costly operation (it usually takes at |
1502 | Establishing the current time is a costly operation (it usually takes at |
1286 | least two system calls): EV therefore updates its idea of the current |
1503 | least two system calls): EV therefore updates its idea of the current |
1287 | time only before and after C<ev_loop> collects new events, which causes a |
1504 | time only before and after C<ev_loop> collects new events, which causes a |
… | |
… | |
1330 | If the timer is started but non-repeating, stop it (as if it timed out). |
1547 | If the timer is started but non-repeating, stop it (as if it timed out). |
1331 | |
1548 | |
1332 | If the timer is repeating, either start it if necessary (with the |
1549 | If the timer is repeating, either start it if necessary (with the |
1333 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1550 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1334 | |
1551 | |
1335 | This sounds a bit complicated, but here is a useful and typical |
1552 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1336 | example: Imagine you have a TCP connection and you want a so-called idle |
1553 | usage example. |
1337 | timeout, that is, you want to be called when there have been, say, 60 |
|
|
1338 | seconds of inactivity on the socket. The easiest way to do this is to |
|
|
1339 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
|
|
1340 | C<ev_timer_again> each time you successfully read or write some data. If |
|
|
1341 | you go into an idle state where you do not expect data to travel on the |
|
|
1342 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1343 | automatically restart it if need be. |
|
|
1344 | |
|
|
1345 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1346 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1347 | |
|
|
1348 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1349 | ev_timer_again (loop, timer); |
|
|
1350 | ... |
|
|
1351 | timer->again = 17.; |
|
|
1352 | ev_timer_again (loop, timer); |
|
|
1353 | ... |
|
|
1354 | timer->again = 10.; |
|
|
1355 | ev_timer_again (loop, timer); |
|
|
1356 | |
|
|
1357 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1358 | you want to modify its timeout value. |
|
|
1359 | |
|
|
1360 | Note, however, that it is often even more efficient to remember the |
|
|
1361 | time of the last activity and let the timer time-out naturally. In the |
|
|
1362 | callback, you then check whether the time-out is real, or, if there was |
|
|
1363 | some activity, you reschedule the watcher to time-out in "last_activity + |
|
|
1364 | timeout - ev_now ()" seconds. |
|
|
1365 | |
1554 | |
1366 | =item ev_tstamp repeat [read-write] |
1555 | =item ev_tstamp repeat [read-write] |
1367 | |
1556 | |
1368 | The current C<repeat> value. Will be used each time the watcher times out |
1557 | The current C<repeat> value. Will be used each time the watcher times out |
1369 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1558 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1374 | =head3 Examples |
1563 | =head3 Examples |
1375 | |
1564 | |
1376 | Example: Create a timer that fires after 60 seconds. |
1565 | Example: Create a timer that fires after 60 seconds. |
1377 | |
1566 | |
1378 | static void |
1567 | static void |
1379 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1568 | one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1380 | { |
1569 | { |
1381 | .. one minute over, w is actually stopped right here |
1570 | .. one minute over, w is actually stopped right here |
1382 | } |
1571 | } |
1383 | |
1572 | |
1384 | struct ev_timer mytimer; |
1573 | ev_timer mytimer; |
1385 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1574 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1386 | ev_timer_start (loop, &mytimer); |
1575 | ev_timer_start (loop, &mytimer); |
1387 | |
1576 | |
1388 | Example: Create a timeout timer that times out after 10 seconds of |
1577 | Example: Create a timeout timer that times out after 10 seconds of |
1389 | inactivity. |
1578 | inactivity. |
1390 | |
1579 | |
1391 | static void |
1580 | static void |
1392 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1581 | timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1393 | { |
1582 | { |
1394 | .. ten seconds without any activity |
1583 | .. ten seconds without any activity |
1395 | } |
1584 | } |
1396 | |
1585 | |
1397 | struct ev_timer mytimer; |
1586 | ev_timer mytimer; |
1398 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1587 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1399 | ev_timer_again (&mytimer); /* start timer */ |
1588 | ev_timer_again (&mytimer); /* start timer */ |
1400 | ev_loop (loop, 0); |
1589 | ev_loop (loop, 0); |
1401 | |
1590 | |
1402 | // and in some piece of code that gets executed on any "activity": |
1591 | // and in some piece of code that gets executed on any "activity": |
… | |
… | |
1488 | |
1677 | |
1489 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1678 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1490 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1679 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1491 | only event loop modification you are allowed to do). |
1680 | only event loop modification you are allowed to do). |
1492 | |
1681 | |
1493 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1682 | The callback prototype is C<ev_tstamp (*reschedule_cb)(ev_periodic |
1494 | *w, ev_tstamp now)>, e.g.: |
1683 | *w, ev_tstamp now)>, e.g.: |
1495 | |
1684 | |
|
|
1685 | static ev_tstamp |
1496 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1686 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
1497 | { |
1687 | { |
1498 | return now + 60.; |
1688 | return now + 60.; |
1499 | } |
1689 | } |
1500 | |
1690 | |
1501 | It must return the next time to trigger, based on the passed time value |
1691 | It must return the next time to trigger, based on the passed time value |
… | |
… | |
1538 | |
1728 | |
1539 | The current interval value. Can be modified any time, but changes only |
1729 | The current interval value. Can be modified any time, but changes only |
1540 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1730 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1541 | called. |
1731 | called. |
1542 | |
1732 | |
1543 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1733 | =item ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write] |
1544 | |
1734 | |
1545 | The current reschedule callback, or C<0>, if this functionality is |
1735 | The current reschedule callback, or C<0>, if this functionality is |
1546 | switched off. Can be changed any time, but changes only take effect when |
1736 | switched off. Can be changed any time, but changes only take effect when |
1547 | the periodic timer fires or C<ev_periodic_again> is being called. |
1737 | the periodic timer fires or C<ev_periodic_again> is being called. |
1548 | |
1738 | |
… | |
… | |
1553 | Example: Call a callback every hour, or, more precisely, whenever the |
1743 | Example: Call a callback every hour, or, more precisely, whenever the |
1554 | system time is divisible by 3600. The callback invocation times have |
1744 | system time is divisible by 3600. The callback invocation times have |
1555 | potentially a lot of jitter, but good long-term stability. |
1745 | potentially a lot of jitter, but good long-term stability. |
1556 | |
1746 | |
1557 | static void |
1747 | static void |
1558 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1748 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1559 | { |
1749 | { |
1560 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1750 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1561 | } |
1751 | } |
1562 | |
1752 | |
1563 | struct ev_periodic hourly_tick; |
1753 | ev_periodic hourly_tick; |
1564 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1754 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1565 | ev_periodic_start (loop, &hourly_tick); |
1755 | ev_periodic_start (loop, &hourly_tick); |
1566 | |
1756 | |
1567 | Example: The same as above, but use a reschedule callback to do it: |
1757 | Example: The same as above, but use a reschedule callback to do it: |
1568 | |
1758 | |
1569 | #include <math.h> |
1759 | #include <math.h> |
1570 | |
1760 | |
1571 | static ev_tstamp |
1761 | static ev_tstamp |
1572 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1762 | my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1573 | { |
1763 | { |
1574 | return now + (3600. - fmod (now, 3600.)); |
1764 | return now + (3600. - fmod (now, 3600.)); |
1575 | } |
1765 | } |
1576 | |
1766 | |
1577 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1767 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1578 | |
1768 | |
1579 | Example: Call a callback every hour, starting now: |
1769 | Example: Call a callback every hour, starting now: |
1580 | |
1770 | |
1581 | struct ev_periodic hourly_tick; |
1771 | ev_periodic hourly_tick; |
1582 | ev_periodic_init (&hourly_tick, clock_cb, |
1772 | ev_periodic_init (&hourly_tick, clock_cb, |
1583 | fmod (ev_now (loop), 3600.), 3600., 0); |
1773 | fmod (ev_now (loop), 3600.), 3600., 0); |
1584 | ev_periodic_start (loop, &hourly_tick); |
1774 | ev_periodic_start (loop, &hourly_tick); |
1585 | |
1775 | |
1586 | |
1776 | |
… | |
… | |
1628 | =head3 Examples |
1818 | =head3 Examples |
1629 | |
1819 | |
1630 | Example: Try to exit cleanly on SIGINT. |
1820 | Example: Try to exit cleanly on SIGINT. |
1631 | |
1821 | |
1632 | static void |
1822 | static void |
1633 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1823 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1634 | { |
1824 | { |
1635 | ev_unloop (loop, EVUNLOOP_ALL); |
1825 | ev_unloop (loop, EVUNLOOP_ALL); |
1636 | } |
1826 | } |
1637 | |
1827 | |
1638 | struct ev_signal signal_watcher; |
1828 | ev_signal signal_watcher; |
1639 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1829 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1640 | ev_signal_start (loop, &signal_watcher); |
1830 | ev_signal_start (loop, &signal_watcher); |
1641 | |
1831 | |
1642 | |
1832 | |
1643 | =head2 C<ev_child> - watch out for process status changes |
1833 | =head2 C<ev_child> - watch out for process status changes |
… | |
… | |
1718 | its completion. |
1908 | its completion. |
1719 | |
1909 | |
1720 | ev_child cw; |
1910 | ev_child cw; |
1721 | |
1911 | |
1722 | static void |
1912 | static void |
1723 | child_cb (EV_P_ struct ev_child *w, int revents) |
1913 | child_cb (EV_P_ ev_child *w, int revents) |
1724 | { |
1914 | { |
1725 | ev_child_stop (EV_A_ w); |
1915 | ev_child_stop (EV_A_ w); |
1726 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1916 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1727 | } |
1917 | } |
1728 | |
1918 | |
… | |
… | |
1743 | |
1933 | |
1744 | |
1934 | |
1745 | =head2 C<ev_stat> - did the file attributes just change? |
1935 | =head2 C<ev_stat> - did the file attributes just change? |
1746 | |
1936 | |
1747 | This watches a file system path for attribute changes. That is, it calls |
1937 | This watches a file system path for attribute changes. That is, it calls |
1748 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1938 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1749 | compared to the last time, invoking the callback if it did. |
1939 | and sees if it changed compared to the last time, invoking the callback if |
|
|
1940 | it did. |
1750 | |
1941 | |
1751 | The path does not need to exist: changing from "path exists" to "path does |
1942 | The path does not need to exist: changing from "path exists" to "path does |
1752 | not exist" is a status change like any other. The condition "path does |
1943 | not exist" is a status change like any other. The condition "path does not |
1753 | not exist" is signified by the C<st_nlink> field being zero (which is |
1944 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
1754 | otherwise always forced to be at least one) and all the other fields of |
1945 | C<st_nlink> field being zero (which is otherwise always forced to be at |
1755 | the stat buffer having unspecified contents. |
1946 | least one) and all the other fields of the stat buffer having unspecified |
|
|
1947 | contents. |
1756 | |
1948 | |
1757 | The path I<should> be absolute and I<must not> end in a slash. If it is |
1949 | The path I<must not> end in a slash or contain special components such as |
|
|
1950 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1758 | relative and your working directory changes, the behaviour is undefined. |
1951 | your working directory changes, then the behaviour is undefined. |
1759 | |
1952 | |
1760 | Since there is no standard kernel interface to do this, the portable |
1953 | Since there is no portable change notification interface available, the |
1761 | implementation simply calls C<stat (2)> regularly on the path to see if |
1954 | portable implementation simply calls C<stat(2)> regularly on the path |
1762 | it changed somehow. You can specify a recommended polling interval for |
1955 | to see if it changed somehow. You can specify a recommended polling |
1763 | this case. If you specify a polling interval of C<0> (highly recommended!) |
1956 | interval for this case. If you specify a polling interval of C<0> (highly |
1764 | then a I<suitable, unspecified default> value will be used (which |
1957 | recommended!) then a I<suitable, unspecified default> value will be used |
1765 | you can expect to be around five seconds, although this might change |
1958 | (which you can expect to be around five seconds, although this might |
1766 | dynamically). Libev will also impose a minimum interval which is currently |
1959 | change dynamically). Libev will also impose a minimum interval which is |
1767 | around C<0.1>, but thats usually overkill. |
1960 | currently around C<0.1>, but that's usually overkill. |
1768 | |
1961 | |
1769 | This watcher type is not meant for massive numbers of stat watchers, |
1962 | This watcher type is not meant for massive numbers of stat watchers, |
1770 | as even with OS-supported change notifications, this can be |
1963 | as even with OS-supported change notifications, this can be |
1771 | resource-intensive. |
1964 | resource-intensive. |
1772 | |
1965 | |
1773 | At the time of this writing, the only OS-specific interface implemented |
1966 | At the time of this writing, the only OS-specific interface implemented |
1774 | is the Linux inotify interface (implementing kqueue support is left as |
1967 | is the Linux inotify interface (implementing kqueue support is left as an |
1775 | an exercise for the reader. Note, however, that the author sees no way |
1968 | exercise for the reader. Note, however, that the author sees no way of |
1776 | of implementing C<ev_stat> semantics with kqueue). |
1969 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1777 | |
1970 | |
1778 | =head3 ABI Issues (Largefile Support) |
1971 | =head3 ABI Issues (Largefile Support) |
1779 | |
1972 | |
1780 | Libev by default (unless the user overrides this) uses the default |
1973 | Libev by default (unless the user overrides this) uses the default |
1781 | compilation environment, which means that on systems with large file |
1974 | compilation environment, which means that on systems with large file |
1782 | support disabled by default, you get the 32 bit version of the stat |
1975 | support disabled by default, you get the 32 bit version of the stat |
1783 | structure. When using the library from programs that change the ABI to |
1976 | structure. When using the library from programs that change the ABI to |
1784 | use 64 bit file offsets the programs will fail. In that case you have to |
1977 | use 64 bit file offsets the programs will fail. In that case you have to |
1785 | compile libev with the same flags to get binary compatibility. This is |
1978 | compile libev with the same flags to get binary compatibility. This is |
1786 | obviously the case with any flags that change the ABI, but the problem is |
1979 | obviously the case with any flags that change the ABI, but the problem is |
1787 | most noticeably disabled with ev_stat and large file support. |
1980 | most noticeably displayed with ev_stat and large file support. |
1788 | |
1981 | |
1789 | The solution for this is to lobby your distribution maker to make large |
1982 | The solution for this is to lobby your distribution maker to make large |
1790 | file interfaces available by default (as e.g. FreeBSD does) and not |
1983 | file interfaces available by default (as e.g. FreeBSD does) and not |
1791 | optional. Libev cannot simply switch on large file support because it has |
1984 | optional. Libev cannot simply switch on large file support because it has |
1792 | to exchange stat structures with application programs compiled using the |
1985 | to exchange stat structures with application programs compiled using the |
1793 | default compilation environment. |
1986 | default compilation environment. |
1794 | |
1987 | |
1795 | =head3 Inotify and Kqueue |
1988 | =head3 Inotify and Kqueue |
1796 | |
1989 | |
1797 | When C<inotify (7)> support has been compiled into libev (generally only |
1990 | When C<inotify (7)> support has been compiled into libev and present at |
1798 | available with Linux) and present at runtime, it will be used to speed up |
1991 | runtime, it will be used to speed up change detection where possible. The |
1799 | change detection where possible. The inotify descriptor will be created lazily |
1992 | inotify descriptor will be created lazily when the first C<ev_stat> |
1800 | when the first C<ev_stat> watcher is being started. |
1993 | watcher is being started. |
1801 | |
1994 | |
1802 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1995 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1803 | except that changes might be detected earlier, and in some cases, to avoid |
1996 | except that changes might be detected earlier, and in some cases, to avoid |
1804 | making regular C<stat> calls. Even in the presence of inotify support |
1997 | making regular C<stat> calls. Even in the presence of inotify support |
1805 | there are many cases where libev has to resort to regular C<stat> polling, |
1998 | there are many cases where libev has to resort to regular C<stat> polling, |
1806 | but as long as the path exists, libev usually gets away without polling. |
1999 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2000 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2001 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2002 | xfs are fully working) libev usually gets away without polling. |
1807 | |
2003 | |
1808 | There is no support for kqueue, as apparently it cannot be used to |
2004 | There is no support for kqueue, as apparently it cannot be used to |
1809 | implement this functionality, due to the requirement of having a file |
2005 | implement this functionality, due to the requirement of having a file |
1810 | descriptor open on the object at all times, and detecting renames, unlinks |
2006 | descriptor open on the object at all times, and detecting renames, unlinks |
1811 | etc. is difficult. |
2007 | etc. is difficult. |
1812 | |
2008 | |
|
|
2009 | =head3 C<stat ()> is a synchronous operation |
|
|
2010 | |
|
|
2011 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2012 | the process. The exception are C<ev_stat> watchers - those call C<stat |
|
|
2013 | ()>, which is a synchronous operation. |
|
|
2014 | |
|
|
2015 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2016 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2017 | as the path data is usually in memory already (except when starting the |
|
|
2018 | watcher). |
|
|
2019 | |
|
|
2020 | For networked file systems, calling C<stat ()> can block an indefinite |
|
|
2021 | time due to network issues, and even under good conditions, a stat call |
|
|
2022 | often takes multiple milliseconds. |
|
|
2023 | |
|
|
2024 | Therefore, it is best to avoid using C<ev_stat> watchers on networked |
|
|
2025 | paths, although this is fully supported by libev. |
|
|
2026 | |
1813 | =head3 The special problem of stat time resolution |
2027 | =head3 The special problem of stat time resolution |
1814 | |
2028 | |
1815 | The C<stat ()> system call only supports full-second resolution portably, and |
2029 | The C<stat ()> system call only supports full-second resolution portably, |
1816 | even on systems where the resolution is higher, most file systems still |
2030 | and even on systems where the resolution is higher, most file systems |
1817 | only support whole seconds. |
2031 | still only support whole seconds. |
1818 | |
2032 | |
1819 | That means that, if the time is the only thing that changes, you can |
2033 | That means that, if the time is the only thing that changes, you can |
1820 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2034 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1821 | calls your callback, which does something. When there is another update |
2035 | calls your callback, which does something. When there is another update |
1822 | within the same second, C<ev_stat> will be unable to detect unless the |
2036 | within the same second, C<ev_stat> will be unable to detect unless the |
… | |
… | |
1979 | |
2193 | |
1980 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
2194 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1981 | callback, free it. Also, use no error checking, as usual. |
2195 | callback, free it. Also, use no error checking, as usual. |
1982 | |
2196 | |
1983 | static void |
2197 | static void |
1984 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2198 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1985 | { |
2199 | { |
1986 | free (w); |
2200 | free (w); |
1987 | // now do something you wanted to do when the program has |
2201 | // now do something you wanted to do when the program has |
1988 | // no longer anything immediate to do. |
2202 | // no longer anything immediate to do. |
1989 | } |
2203 | } |
1990 | |
2204 | |
1991 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2205 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1992 | ev_idle_init (idle_watcher, idle_cb); |
2206 | ev_idle_init (idle_watcher, idle_cb); |
1993 | ev_idle_start (loop, idle_cb); |
2207 | ev_idle_start (loop, idle_cb); |
1994 | |
2208 | |
1995 | |
2209 | |
1996 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2210 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
… | |
… | |
2077 | |
2291 | |
2078 | static ev_io iow [nfd]; |
2292 | static ev_io iow [nfd]; |
2079 | static ev_timer tw; |
2293 | static ev_timer tw; |
2080 | |
2294 | |
2081 | static void |
2295 | static void |
2082 | io_cb (ev_loop *loop, ev_io *w, int revents) |
2296 | io_cb (struct ev_loop *loop, ev_io *w, int revents) |
2083 | { |
2297 | { |
2084 | } |
2298 | } |
2085 | |
2299 | |
2086 | // create io watchers for each fd and a timer before blocking |
2300 | // create io watchers for each fd and a timer before blocking |
2087 | static void |
2301 | static void |
2088 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2302 | adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
2089 | { |
2303 | { |
2090 | int timeout = 3600000; |
2304 | int timeout = 3600000; |
2091 | struct pollfd fds [nfd]; |
2305 | struct pollfd fds [nfd]; |
2092 | // actual code will need to loop here and realloc etc. |
2306 | // actual code will need to loop here and realloc etc. |
2093 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2307 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
… | |
… | |
2108 | } |
2322 | } |
2109 | } |
2323 | } |
2110 | |
2324 | |
2111 | // stop all watchers after blocking |
2325 | // stop all watchers after blocking |
2112 | static void |
2326 | static void |
2113 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2327 | adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
2114 | { |
2328 | { |
2115 | ev_timer_stop (loop, &tw); |
2329 | ev_timer_stop (loop, &tw); |
2116 | |
2330 | |
2117 | for (int i = 0; i < nfd; ++i) |
2331 | for (int i = 0; i < nfd; ++i) |
2118 | { |
2332 | { |
… | |
… | |
2214 | some fds have to be watched and handled very quickly (with low latency), |
2428 | some fds have to be watched and handled very quickly (with low latency), |
2215 | and even priorities and idle watchers might have too much overhead. In |
2429 | and even priorities and idle watchers might have too much overhead. In |
2216 | this case you would put all the high priority stuff in one loop and all |
2430 | this case you would put all the high priority stuff in one loop and all |
2217 | the rest in a second one, and embed the second one in the first. |
2431 | the rest in a second one, and embed the second one in the first. |
2218 | |
2432 | |
2219 | As long as the watcher is active, the callback will be invoked every time |
2433 | As long as the watcher is active, the callback will be invoked every |
2220 | there might be events pending in the embedded loop. The callback must then |
2434 | time there might be events pending in the embedded loop. The callback |
2221 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2435 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2222 | their callbacks (you could also start an idle watcher to give the embedded |
2436 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2223 | loop strictly lower priority for example). You can also set the callback |
2437 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2224 | to C<0>, in which case the embed watcher will automatically execute the |
2438 | to give the embedded loop strictly lower priority for example). |
2225 | embedded loop sweep. |
|
|
2226 | |
2439 | |
2227 | As long as the watcher is started it will automatically handle events. The |
2440 | You can also set the callback to C<0>, in which case the embed watcher |
2228 | callback will be invoked whenever some events have been handled. You can |
2441 | will automatically execute the embedded loop sweep whenever necessary. |
2229 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2230 | interested in that. |
|
|
2231 | |
2442 | |
2232 | Also, there have not currently been made special provisions for forking: |
2443 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2233 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2444 | is active, i.e., the embedded loop will automatically be forked when the |
2234 | but you will also have to stop and restart any C<ev_embed> watchers |
2445 | embedding loop forks. In other cases, the user is responsible for calling |
2235 | yourself - but you can use a fork watcher to handle this automatically, |
2446 | C<ev_loop_fork> on the embedded loop. |
2236 | and future versions of libev might do just that. |
|
|
2237 | |
2447 | |
2238 | Unfortunately, not all backends are embeddable: only the ones returned by |
2448 | Unfortunately, not all backends are embeddable: only the ones returned by |
2239 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2449 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2240 | portable one. |
2450 | portable one. |
2241 | |
2451 | |
… | |
… | |
2286 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2496 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2287 | used). |
2497 | used). |
2288 | |
2498 | |
2289 | struct ev_loop *loop_hi = ev_default_init (0); |
2499 | struct ev_loop *loop_hi = ev_default_init (0); |
2290 | struct ev_loop *loop_lo = 0; |
2500 | struct ev_loop *loop_lo = 0; |
2291 | struct ev_embed embed; |
2501 | ev_embed embed; |
2292 | |
2502 | |
2293 | // see if there is a chance of getting one that works |
2503 | // see if there is a chance of getting one that works |
2294 | // (remember that a flags value of 0 means autodetection) |
2504 | // (remember that a flags value of 0 means autodetection) |
2295 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2505 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2296 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2506 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
… | |
… | |
2310 | kqueue implementation). Store the kqueue/socket-only event loop in |
2520 | kqueue implementation). Store the kqueue/socket-only event loop in |
2311 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2521 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2312 | |
2522 | |
2313 | struct ev_loop *loop = ev_default_init (0); |
2523 | struct ev_loop *loop = ev_default_init (0); |
2314 | struct ev_loop *loop_socket = 0; |
2524 | struct ev_loop *loop_socket = 0; |
2315 | struct ev_embed embed; |
2525 | ev_embed embed; |
2316 | |
2526 | |
2317 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2527 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2318 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2528 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2319 | { |
2529 | { |
2320 | ev_embed_init (&embed, 0, loop_socket); |
2530 | ev_embed_init (&embed, 0, loop_socket); |
… | |
… | |
2461 | =over 4 |
2671 | =over 4 |
2462 | |
2672 | |
2463 | =item ev_async_init (ev_async *, callback) |
2673 | =item ev_async_init (ev_async *, callback) |
2464 | |
2674 | |
2465 | Initialises and configures the async watcher - it has no parameters of any |
2675 | Initialises and configures the async watcher - it has no parameters of any |
2466 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2676 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2467 | trust me. |
2677 | trust me. |
2468 | |
2678 | |
2469 | =item ev_async_send (loop, ev_async *) |
2679 | =item ev_async_send (loop, ev_async *) |
2470 | |
2680 | |
2471 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2681 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
… | |
… | |
2534 | /* doh, nothing entered */; |
2744 | /* doh, nothing entered */; |
2535 | } |
2745 | } |
2536 | |
2746 | |
2537 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2747 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2538 | |
2748 | |
2539 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2749 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
2540 | |
2750 | |
2541 | Feeds the given event set into the event loop, as if the specified event |
2751 | Feeds the given event set into the event loop, as if the specified event |
2542 | had happened for the specified watcher (which must be a pointer to an |
2752 | had happened for the specified watcher (which must be a pointer to an |
2543 | initialised but not necessarily started event watcher). |
2753 | initialised but not necessarily started event watcher). |
2544 | |
2754 | |
2545 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
2755 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
2546 | |
2756 | |
2547 | Feed an event on the given fd, as if a file descriptor backend detected |
2757 | Feed an event on the given fd, as if a file descriptor backend detected |
2548 | the given events it. |
2758 | the given events it. |
2549 | |
2759 | |
2550 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2760 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
2551 | |
2761 | |
2552 | Feed an event as if the given signal occurred (C<loop> must be the default |
2762 | Feed an event as if the given signal occurred (C<loop> must be the default |
2553 | loop!). |
2763 | loop!). |
2554 | |
2764 | |
2555 | =back |
2765 | =back |
… | |
… | |
2676 | } |
2886 | } |
2677 | |
2887 | |
2678 | myclass obj; |
2888 | myclass obj; |
2679 | ev::io iow; |
2889 | ev::io iow; |
2680 | iow.set <myclass, &myclass::io_cb> (&obj); |
2890 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2891 | |
|
|
2892 | =item w->set (object *) |
|
|
2893 | |
|
|
2894 | This is an B<experimental> feature that might go away in a future version. |
|
|
2895 | |
|
|
2896 | This is a variation of a method callback - leaving out the method to call |
|
|
2897 | will default the method to C<operator ()>, which makes it possible to use |
|
|
2898 | functor objects without having to manually specify the C<operator ()> all |
|
|
2899 | the time. Incidentally, you can then also leave out the template argument |
|
|
2900 | list. |
|
|
2901 | |
|
|
2902 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
2903 | int revents)>. |
|
|
2904 | |
|
|
2905 | See the method-C<set> above for more details. |
|
|
2906 | |
|
|
2907 | Example: use a functor object as callback. |
|
|
2908 | |
|
|
2909 | struct myfunctor |
|
|
2910 | { |
|
|
2911 | void operator() (ev::io &w, int revents) |
|
|
2912 | { |
|
|
2913 | ... |
|
|
2914 | } |
|
|
2915 | } |
|
|
2916 | |
|
|
2917 | myfunctor f; |
|
|
2918 | |
|
|
2919 | ev::io w; |
|
|
2920 | w.set (&f); |
2681 | |
2921 | |
2682 | =item w->set<function> (void *data = 0) |
2922 | =item w->set<function> (void *data = 0) |
2683 | |
2923 | |
2684 | Also sets a callback, but uses a static method or plain function as |
2924 | Also sets a callback, but uses a static method or plain function as |
2685 | callback. The optional C<data> argument will be stored in the watcher's |
2925 | callback. The optional C<data> argument will be stored in the watcher's |
… | |
… | |
2785 | Tony Arcieri has written a ruby extension that offers access to a subset |
3025 | Tony Arcieri has written a ruby extension that offers access to a subset |
2786 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3026 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2787 | more on top of it. It can be found via gem servers. Its homepage is at |
3027 | more on top of it. It can be found via gem servers. Its homepage is at |
2788 | L<http://rev.rubyforge.org/>. |
3028 | L<http://rev.rubyforge.org/>. |
2789 | |
3029 | |
|
|
3030 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3031 | makes rev work even on mingw. |
|
|
3032 | |
2790 | =item D |
3033 | =item D |
2791 | |
3034 | |
2792 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3035 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2793 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3036 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
|
|
3037 | |
|
|
3038 | =item Ocaml |
|
|
3039 | |
|
|
3040 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3041 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
2794 | |
3042 | |
2795 | =back |
3043 | =back |
2796 | |
3044 | |
2797 | |
3045 | |
2798 | =head1 MACRO MAGIC |
3046 | =head1 MACRO MAGIC |
… | |
… | |
2899 | |
3147 | |
2900 | #define EV_STANDALONE 1 |
3148 | #define EV_STANDALONE 1 |
2901 | #include "ev.h" |
3149 | #include "ev.h" |
2902 | |
3150 | |
2903 | Both header files and implementation files can be compiled with a C++ |
3151 | Both header files and implementation files can be compiled with a C++ |
2904 | compiler (at least, thats a stated goal, and breakage will be treated |
3152 | compiler (at least, that's a stated goal, and breakage will be treated |
2905 | as a bug). |
3153 | as a bug). |
2906 | |
3154 | |
2907 | You need the following files in your source tree, or in a directory |
3155 | You need the following files in your source tree, or in a directory |
2908 | in your include path (e.g. in libev/ when using -Ilibev): |
3156 | in your include path (e.g. in libev/ when using -Ilibev): |
2909 | |
3157 | |
… | |
… | |
2965 | keeps libev from including F<config.h>, and it also defines dummy |
3213 | keeps libev from including F<config.h>, and it also defines dummy |
2966 | implementations for some libevent functions (such as logging, which is not |
3214 | implementations for some libevent functions (such as logging, which is not |
2967 | supported). It will also not define any of the structs usually found in |
3215 | supported). It will also not define any of the structs usually found in |
2968 | F<event.h> that are not directly supported by the libev core alone. |
3216 | F<event.h> that are not directly supported by the libev core alone. |
2969 | |
3217 | |
|
|
3218 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3219 | configuration, but has to be more conservative. |
|
|
3220 | |
2970 | =item EV_USE_MONOTONIC |
3221 | =item EV_USE_MONOTONIC |
2971 | |
3222 | |
2972 | If defined to be C<1>, libev will try to detect the availability of the |
3223 | If defined to be C<1>, libev will try to detect the availability of the |
2973 | monotonic clock option at both compile time and runtime. Otherwise no use |
3224 | monotonic clock option at both compile time and runtime. Otherwise no |
2974 | of the monotonic clock option will be attempted. If you enable this, you |
3225 | use of the monotonic clock option will be attempted. If you enable this, |
2975 | usually have to link against librt or something similar. Enabling it when |
3226 | you usually have to link against librt or something similar. Enabling it |
2976 | the functionality isn't available is safe, though, although you have |
3227 | when the functionality isn't available is safe, though, although you have |
2977 | to make sure you link against any libraries where the C<clock_gettime> |
3228 | to make sure you link against any libraries where the C<clock_gettime> |
2978 | function is hiding in (often F<-lrt>). |
3229 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
2979 | |
3230 | |
2980 | =item EV_USE_REALTIME |
3231 | =item EV_USE_REALTIME |
2981 | |
3232 | |
2982 | If defined to be C<1>, libev will try to detect the availability of the |
3233 | If defined to be C<1>, libev will try to detect the availability of the |
2983 | real-time clock option at compile time (and assume its availability at |
3234 | real-time clock option at compile time (and assume its availability |
2984 | runtime if successful). Otherwise no use of the real-time clock option will |
3235 | at runtime if successful). Otherwise no use of the real-time clock |
2985 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3236 | option will be attempted. This effectively replaces C<gettimeofday> |
2986 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3237 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
2987 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3238 | correctness. See the note about libraries in the description of |
|
|
3239 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3240 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3241 | |
|
|
3242 | =item EV_USE_CLOCK_SYSCALL |
|
|
3243 | |
|
|
3244 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3245 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3246 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3247 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3248 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3249 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3250 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3251 | higher, as it simplifies linking (no need for C<-lrt>). |
2988 | |
3252 | |
2989 | =item EV_USE_NANOSLEEP |
3253 | =item EV_USE_NANOSLEEP |
2990 | |
3254 | |
2991 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3255 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2992 | and will use it for delays. Otherwise it will use C<select ()>. |
3256 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3008 | |
3272 | |
3009 | =item EV_SELECT_USE_FD_SET |
3273 | =item EV_SELECT_USE_FD_SET |
3010 | |
3274 | |
3011 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3275 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3012 | structure. This is useful if libev doesn't compile due to a missing |
3276 | structure. This is useful if libev doesn't compile due to a missing |
3013 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3277 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3014 | exotic systems. This usually limits the range of file descriptors to some |
3278 | on exotic systems. This usually limits the range of file descriptors to |
3015 | low limit such as 1024 or might have other limitations (winsocket only |
3279 | some low limit such as 1024 or might have other limitations (winsocket |
3016 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3280 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3017 | influence the size of the C<fd_set> used. |
3281 | configures the maximum size of the C<fd_set>. |
3018 | |
3282 | |
3019 | =item EV_SELECT_IS_WINSOCKET |
3283 | =item EV_SELECT_IS_WINSOCKET |
3020 | |
3284 | |
3021 | When defined to C<1>, the select backend will assume that |
3285 | When defined to C<1>, the select backend will assume that |
3022 | select/socket/connect etc. don't understand file descriptors but |
3286 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3381 | loop, as long as you don't confuse yourself). The only exception is that |
3645 | loop, as long as you don't confuse yourself). The only exception is that |
3382 | you must not do this from C<ev_periodic> reschedule callbacks. |
3646 | you must not do this from C<ev_periodic> reschedule callbacks. |
3383 | |
3647 | |
3384 | Care has been taken to ensure that libev does not keep local state inside |
3648 | Care has been taken to ensure that libev does not keep local state inside |
3385 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3649 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3386 | they do not clal any callbacks. |
3650 | they do not call any callbacks. |
3387 | |
3651 | |
3388 | =head2 COMPILER WARNINGS |
3652 | =head2 COMPILER WARNINGS |
3389 | |
3653 | |
3390 | Depending on your compiler and compiler settings, you might get no or a |
3654 | Depending on your compiler and compiler settings, you might get no or a |
3391 | lot of warnings when compiling libev code. Some people are apparently |
3655 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3425 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3689 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3426 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3690 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3427 | ==2274== still reachable: 256 bytes in 1 blocks. |
3691 | ==2274== still reachable: 256 bytes in 1 blocks. |
3428 | |
3692 | |
3429 | Then there is no memory leak, just as memory accounted to global variables |
3693 | Then there is no memory leak, just as memory accounted to global variables |
3430 | is not a memleak - the memory is still being refernced, and didn't leak. |
3694 | is not a memleak - the memory is still being referenced, and didn't leak. |
3431 | |
3695 | |
3432 | Similarly, under some circumstances, valgrind might report kernel bugs |
3696 | Similarly, under some circumstances, valgrind might report kernel bugs |
3433 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3697 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3434 | although an acceptable workaround has been found here), or it might be |
3698 | although an acceptable workaround has been found here), or it might be |
3435 | confused. |
3699 | confused. |
… | |
… | |
3673 | =back |
3937 | =back |
3674 | |
3938 | |
3675 | |
3939 | |
3676 | =head1 AUTHOR |
3940 | =head1 AUTHOR |
3677 | |
3941 | |
3678 | Marc Lehmann <libev@schmorp.de>. |
3942 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3679 | |
3943 | |