… | |
… | |
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 |
… | |
… | |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = ev_default_loop (0); |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
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<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 |
|
|
288 | supports signals and child events, and dynamically created loops which do |
|
|
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>). |
… | |
… | |
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 | ev_signal exitsig; |
770 | ev_signal exitsig; |
… | |
… | |
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 |
… | |
… | |
781 | |
836 | |
782 | =back |
837 | =back |
783 | |
838 | |
784 | |
839 | |
785 | =head1 ANATOMY OF A WATCHER |
840 | =head1 ANATOMY OF A WATCHER |
|
|
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. |
786 | |
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 | |
… | |
… | |
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 | 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 |
… | |
… | |
912 | |
982 | |
913 | =back |
983 | =back |
914 | |
984 | |
915 | =head2 GENERIC WATCHER FUNCTIONS |
985 | =head2 GENERIC WATCHER FUNCTIONS |
916 | |
986 | |
917 | In the following description, C<TYPE> stands for the watcher type, |
|
|
918 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
919 | |
|
|
920 | =over 4 |
987 | =over 4 |
921 | |
988 | |
922 | =item C<ev_init> (ev_TYPE *watcher, callback) |
989 | =item C<ev_init> (ev_TYPE *watcher, callback) |
923 | |
990 | |
924 | This macro initialises the generic portion of a watcher. The contents |
991 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1032 | The default priority used by watchers when no priority has been set is |
1099 | The default priority used by watchers when no priority has been set is |
1033 | always C<0>, which is supposed to not be too high and not be too low :). |
1100 | always C<0>, which is supposed to not be too high and not be too low :). |
1034 | |
1101 | |
1035 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1102 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1036 | fine, as long as you do not mind that the priority value you query might |
1103 | fine, as long as you do not mind that the priority value you query might |
1037 | or might not have been adjusted to be within valid range. |
1104 | or might not have been clamped to the valid range. |
1038 | |
1105 | |
1039 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1106 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1040 | |
1107 | |
1041 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1108 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1042 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1109 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1283 | year, it will still time out after (roughly) one hour. "Roughly" because |
1350 | year, it will still time out after (roughly) one hour. "Roughly" because |
1284 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1351 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1285 | monotonic clock option helps a lot here). |
1352 | monotonic clock option helps a lot here). |
1286 | |
1353 | |
1287 | The callback is guaranteed to be invoked only I<after> its timeout has |
1354 | The callback is guaranteed to be invoked only I<after> its timeout has |
1288 | passed, but if multiple timers become ready during the same loop iteration |
1355 | passed. If multiple timers become ready during the same loop iteration |
1289 | then order of execution is undefined. |
1356 | then the ones with earlier time-out values are invoked before ones with |
|
|
1357 | later time-out values (but this is no longer true when a callback calls |
|
|
1358 | C<ev_loop> recursively). |
1290 | |
1359 | |
1291 | =head3 Be smart about timeouts |
1360 | =head3 Be smart about timeouts |
1292 | |
1361 | |
1293 | Many real-world problems involve some kind of timeout, usually for error |
1362 | Many real-world problems involve some kind of timeout, usually for error |
1294 | recovery. A typical example is an HTTP request - if the other side hangs, |
1363 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1387 | else |
1456 | else |
1388 | { |
1457 | { |
1389 | // callback was invoked, but there was some activity, re-arm |
1458 | // callback was invoked, but there was some activity, re-arm |
1390 | // the watcher to fire in last_activity + 60, which is |
1459 | // the watcher to fire in last_activity + 60, which is |
1391 | // guaranteed to be in the future, so "again" is positive: |
1460 | // guaranteed to be in the future, so "again" is positive: |
1392 | w->again = timeout - now; |
1461 | w->repeat = timeout - now; |
1393 | ev_timer_again (EV_A_ w); |
1462 | ev_timer_again (EV_A_ w); |
1394 | } |
1463 | } |
1395 | } |
1464 | } |
1396 | |
1465 | |
1397 | To summarise the callback: first calculate the real timeout (defined |
1466 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
1426 | |
1495 | |
1427 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1496 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1428 | callback :) - just change the timeout and invoke the callback, which will |
1497 | callback :) - just change the timeout and invoke the callback, which will |
1429 | fix things for you. |
1498 | fix things for you. |
1430 | |
1499 | |
1431 | =item 4. Whee, use a double-linked list for your timeouts. |
1500 | =item 4. Wee, just use a double-linked list for your timeouts. |
1432 | |
1501 | |
1433 | If there is not one request, but many thousands, all employing some kind |
1502 | If there is not one request, but many thousands (millions...), all |
1434 | of timeout with the same timeout value, then one can do even better: |
1503 | employing some kind of timeout with the same timeout value, then one can |
|
|
1504 | do even better: |
1435 | |
1505 | |
1436 | When starting the timeout, calculate the timeout value and put the timeout |
1506 | When starting the timeout, calculate the timeout value and put the timeout |
1437 | at the I<end> of the list. |
1507 | at the I<end> of the list. |
1438 | |
1508 | |
1439 | Then use an C<ev_timer> to fire when the timeout at the I<beginning> of |
1509 | Then use an C<ev_timer> to fire when the timeout at the I<beginning> of |
… | |
… | |
1448 | complication, and having to use a constant timeout. The constant timeout |
1518 | complication, and having to use a constant timeout. The constant timeout |
1449 | ensures that the list stays sorted. |
1519 | ensures that the list stays sorted. |
1450 | |
1520 | |
1451 | =back |
1521 | =back |
1452 | |
1522 | |
1453 | So what method is the best? |
1523 | So which method the best? |
1454 | |
1524 | |
1455 | The method #2 is a simple no-brain-required solution that is adequate in |
1525 | Method #2 is a simple no-brain-required solution that is adequate in most |
1456 | most situations. Method #3 requires a bit more thinking, but handles many |
1526 | situations. Method #3 requires a bit more thinking, but handles many cases |
1457 | cases better, and isn't very complicated either. In most case, choosing |
1527 | better, and isn't very complicated either. In most case, choosing either |
1458 | either one is fine. |
1528 | one is fine, with #3 being better in typical situations. |
1459 | |
1529 | |
1460 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1530 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1461 | rather complicated, but extremely efficient, something that really pays |
1531 | rather complicated, but extremely efficient, something that really pays |
1462 | off after the first or so million of active timers, i.e. it's usually |
1532 | off after the first million or so of active timers, i.e. it's usually |
1463 | overkill :) |
1533 | overkill :) |
1464 | |
1534 | |
1465 | =head3 The special problem of time updates |
1535 | =head3 The special problem of time updates |
1466 | |
1536 | |
1467 | Establishing the current time is a costly operation (it usually takes at |
1537 | Establishing the current time is a costly operation (it usually takes at |
… | |
… | |
1561 | =head2 C<ev_periodic> - to cron or not to cron? |
1631 | =head2 C<ev_periodic> - to cron or not to cron? |
1562 | |
1632 | |
1563 | Periodic watchers are also timers of a kind, but they are very versatile |
1633 | Periodic watchers are also timers of a kind, but they are very versatile |
1564 | (and unfortunately a bit complex). |
1634 | (and unfortunately a bit complex). |
1565 | |
1635 | |
1566 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1636 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1567 | but on wall clock time (absolute time). You can tell a periodic watcher |
1637 | relative time, the physical time that passes) but on wall clock time |
1568 | to trigger after some specific point in time. For example, if you tell a |
1638 | (absolute time, the thing you can read on your calender or clock). The |
1569 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1639 | difference is that wall clock time can run faster or slower than real |
1570 | + 10.>, that is, an absolute time not a delay) and then reset your system |
1640 | time, and time jumps are not uncommon (e.g. when you adjust your |
1571 | clock to January of the previous year, then it will take more than year |
1641 | wrist-watch). |
1572 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
|
|
1573 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1574 | |
1642 | |
|
|
1643 | You can tell a periodic watcher to trigger after some specific point |
|
|
1644 | in time: for example, if you tell a periodic watcher to trigger "in 10 |
|
|
1645 | seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time |
|
|
1646 | not a delay) and then reset your system clock to January of the previous |
|
|
1647 | year, then it will take a year or more to trigger the event (unlike an |
|
|
1648 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
|
|
1649 | it, as it uses a relative timeout). |
|
|
1650 | |
1575 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1651 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1576 | such as triggering an event on each "midnight, local time", or other |
1652 | timers, such as triggering an event on each "midnight, local time", or |
1577 | complicated rules. |
1653 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
|
|
1654 | those cannot react to time jumps. |
1578 | |
1655 | |
1579 | As with timers, the callback is guaranteed to be invoked only when the |
1656 | As with timers, the callback is guaranteed to be invoked only when the |
1580 | time (C<at>) has passed, but if multiple periodic timers become ready |
1657 | point in time where it is supposed to trigger has passed. If multiple |
1581 | during the same loop iteration, then order of execution is undefined. |
1658 | timers become ready during the same loop iteration then the ones with |
|
|
1659 | earlier time-out values are invoked before ones with later time-out values |
|
|
1660 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
1582 | |
1661 | |
1583 | =head3 Watcher-Specific Functions and Data Members |
1662 | =head3 Watcher-Specific Functions and Data Members |
1584 | |
1663 | |
1585 | =over 4 |
1664 | =over 4 |
1586 | |
1665 | |
1587 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1666 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1588 | |
1667 | |
1589 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1668 | =item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1590 | |
1669 | |
1591 | Lots of arguments, lets sort it out... There are basically three modes of |
1670 | Lots of arguments, let's sort it out... There are basically three modes of |
1592 | operation, and we will explain them from simplest to most complex: |
1671 | operation, and we will explain them from simplest to most complex: |
1593 | |
1672 | |
1594 | =over 4 |
1673 | =over 4 |
1595 | |
1674 | |
1596 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1675 | =item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1597 | |
1676 | |
1598 | In this configuration the watcher triggers an event after the wall clock |
1677 | In this configuration the watcher triggers an event after the wall clock |
1599 | time C<at> has passed. It will not repeat and will not adjust when a time |
1678 | time C<offset> has passed. It will not repeat and will not adjust when a |
1600 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1679 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1601 | only run when the system clock reaches or surpasses this time. |
1680 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
1681 | this point in time. |
1602 | |
1682 | |
1603 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1683 | =item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1604 | |
1684 | |
1605 | In this mode the watcher will always be scheduled to time out at the next |
1685 | In this mode the watcher will always be scheduled to time out at the next |
1606 | C<at + N * interval> time (for some integer N, which can also be negative) |
1686 | C<offset + N * interval> time (for some integer N, which can also be |
1607 | and then repeat, regardless of any time jumps. |
1687 | negative) and then repeat, regardless of any time jumps. The C<offset> |
|
|
1688 | argument is merely an offset into the C<interval> periods. |
1608 | |
1689 | |
1609 | This can be used to create timers that do not drift with respect to the |
1690 | This can be used to create timers that do not drift with respect to the |
1610 | system clock, for example, here is a C<ev_periodic> that triggers each |
1691 | system clock, for example, here is an C<ev_periodic> that triggers each |
1611 | hour, on the hour: |
1692 | hour, on the hour (with respect to UTC): |
1612 | |
1693 | |
1613 | ev_periodic_set (&periodic, 0., 3600., 0); |
1694 | ev_periodic_set (&periodic, 0., 3600., 0); |
1614 | |
1695 | |
1615 | This doesn't mean there will always be 3600 seconds in between triggers, |
1696 | This doesn't mean there will always be 3600 seconds in between triggers, |
1616 | but only that the callback will be called when the system time shows a |
1697 | but only that the callback will be called when the system time shows a |
1617 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1698 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1618 | by 3600. |
1699 | by 3600. |
1619 | |
1700 | |
1620 | Another way to think about it (for the mathematically inclined) is that |
1701 | Another way to think about it (for the mathematically inclined) is that |
1621 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1702 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1622 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1703 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1623 | |
1704 | |
1624 | For numerical stability it is preferable that the C<at> value is near |
1705 | For numerical stability it is preferable that the C<offset> value is near |
1625 | C<ev_now ()> (the current time), but there is no range requirement for |
1706 | C<ev_now ()> (the current time), but there is no range requirement for |
1626 | this value, and in fact is often specified as zero. |
1707 | this value, and in fact is often specified as zero. |
1627 | |
1708 | |
1628 | Note also that there is an upper limit to how often a timer can fire (CPU |
1709 | Note also that there is an upper limit to how often a timer can fire (CPU |
1629 | speed for example), so if C<interval> is very small then timing stability |
1710 | speed for example), so if C<interval> is very small then timing stability |
1630 | will of course deteriorate. Libev itself tries to be exact to be about one |
1711 | will of course deteriorate. Libev itself tries to be exact to be about one |
1631 | millisecond (if the OS supports it and the machine is fast enough). |
1712 | millisecond (if the OS supports it and the machine is fast enough). |
1632 | |
1713 | |
1633 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1714 | =item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1634 | |
1715 | |
1635 | In this mode the values for C<interval> and C<at> are both being |
1716 | In this mode the values for C<interval> and C<offset> are both being |
1636 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1717 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1637 | reschedule callback will be called with the watcher as first, and the |
1718 | reschedule callback will be called with the watcher as first, and the |
1638 | current time as second argument. |
1719 | current time as second argument. |
1639 | |
1720 | |
1640 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1721 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever, |
1641 | ever, or make ANY event loop modifications whatsoever>. |
1722 | or make ANY other event loop modifications whatsoever, unless explicitly |
|
|
1723 | allowed by documentation here>. |
1642 | |
1724 | |
1643 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1725 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1644 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1726 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1645 | only event loop modification you are allowed to do). |
1727 | only event loop modification you are allowed to do). |
1646 | |
1728 | |
… | |
… | |
1676 | a different time than the last time it was called (e.g. in a crond like |
1758 | a different time than the last time it was called (e.g. in a crond like |
1677 | program when the crontabs have changed). |
1759 | program when the crontabs have changed). |
1678 | |
1760 | |
1679 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1761 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1680 | |
1762 | |
1681 | When active, returns the absolute time that the watcher is supposed to |
1763 | When active, returns the absolute time that the watcher is supposed |
1682 | trigger next. |
1764 | to trigger next. This is not the same as the C<offset> argument to |
|
|
1765 | C<ev_periodic_set>, but indeed works even in interval and manual |
|
|
1766 | rescheduling modes. |
1683 | |
1767 | |
1684 | =item ev_tstamp offset [read-write] |
1768 | =item ev_tstamp offset [read-write] |
1685 | |
1769 | |
1686 | When repeating, this contains the offset value, otherwise this is the |
1770 | When repeating, this contains the offset value, otherwise this is the |
1687 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
1771 | absolute point in time (the C<offset> value passed to C<ev_periodic_set>, |
|
|
1772 | although libev might modify this value for better numerical stability). |
1688 | |
1773 | |
1689 | Can be modified any time, but changes only take effect when the periodic |
1774 | Can be modified any time, but changes only take effect when the periodic |
1690 | timer fires or C<ev_periodic_again> is being called. |
1775 | timer fires or C<ev_periodic_again> is being called. |
1691 | |
1776 | |
1692 | =item ev_tstamp interval [read-write] |
1777 | =item ev_tstamp interval [read-write] |
… | |
… | |
1898 | |
1983 | |
1899 | |
1984 | |
1900 | =head2 C<ev_stat> - did the file attributes just change? |
1985 | =head2 C<ev_stat> - did the file attributes just change? |
1901 | |
1986 | |
1902 | This watches a file system path for attribute changes. That is, it calls |
1987 | This watches a file system path for attribute changes. That is, it calls |
1903 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1988 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1904 | compared to the last time, invoking the callback if it did. |
1989 | and sees if it changed compared to the last time, invoking the callback if |
|
|
1990 | it did. |
1905 | |
1991 | |
1906 | The path does not need to exist: changing from "path exists" to "path does |
1992 | The path does not need to exist: changing from "path exists" to "path does |
1907 | not exist" is a status change like any other. The condition "path does |
1993 | not exist" is a status change like any other. The condition "path does not |
1908 | not exist" is signified by the C<st_nlink> field being zero (which is |
1994 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
1909 | otherwise always forced to be at least one) and all the other fields of |
1995 | C<st_nlink> field being zero (which is otherwise always forced to be at |
1910 | the stat buffer having unspecified contents. |
1996 | least one) and all the other fields of the stat buffer having unspecified |
|
|
1997 | contents. |
1911 | |
1998 | |
1912 | The path I<should> be absolute and I<must not> end in a slash. If it is |
1999 | The path I<must not> end in a slash or contain special components such as |
|
|
2000 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1913 | relative and your working directory changes, the behaviour is undefined. |
2001 | your working directory changes, then the behaviour is undefined. |
1914 | |
2002 | |
1915 | Since there is no standard kernel interface to do this, the portable |
2003 | Since there is no portable change notification interface available, the |
1916 | implementation simply calls C<stat (2)> regularly on the path to see if |
2004 | portable implementation simply calls C<stat(2)> regularly on the path |
1917 | it changed somehow. You can specify a recommended polling interval for |
2005 | to see if it changed somehow. You can specify a recommended polling |
1918 | this case. If you specify a polling interval of C<0> (highly recommended!) |
2006 | interval for this case. If you specify a polling interval of C<0> (highly |
1919 | then a I<suitable, unspecified default> value will be used (which |
2007 | recommended!) then a I<suitable, unspecified default> value will be used |
1920 | you can expect to be around five seconds, although this might change |
2008 | (which you can expect to be around five seconds, although this might |
1921 | dynamically). Libev will also impose a minimum interval which is currently |
2009 | change dynamically). Libev will also impose a minimum interval which is |
1922 | around C<0.1>, but thats usually overkill. |
2010 | currently around C<0.1>, but that's usually overkill. |
1923 | |
2011 | |
1924 | This watcher type is not meant for massive numbers of stat watchers, |
2012 | This watcher type is not meant for massive numbers of stat watchers, |
1925 | as even with OS-supported change notifications, this can be |
2013 | as even with OS-supported change notifications, this can be |
1926 | resource-intensive. |
2014 | resource-intensive. |
1927 | |
2015 | |
1928 | At the time of this writing, the only OS-specific interface implemented |
2016 | At the time of this writing, the only OS-specific interface implemented |
1929 | is the Linux inotify interface (implementing kqueue support is left as |
2017 | is the Linux inotify interface (implementing kqueue support is left as an |
1930 | an exercise for the reader. Note, however, that the author sees no way |
2018 | exercise for the reader. Note, however, that the author sees no way of |
1931 | of implementing C<ev_stat> semantics with kqueue). |
2019 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1932 | |
2020 | |
1933 | =head3 ABI Issues (Largefile Support) |
2021 | =head3 ABI Issues (Largefile Support) |
1934 | |
2022 | |
1935 | Libev by default (unless the user overrides this) uses the default |
2023 | Libev by default (unless the user overrides this) uses the default |
1936 | compilation environment, which means that on systems with large file |
2024 | compilation environment, which means that on systems with large file |
1937 | support disabled by default, you get the 32 bit version of the stat |
2025 | support disabled by default, you get the 32 bit version of the stat |
1938 | structure. When using the library from programs that change the ABI to |
2026 | structure. When using the library from programs that change the ABI to |
1939 | use 64 bit file offsets the programs will fail. In that case you have to |
2027 | use 64 bit file offsets the programs will fail. In that case you have to |
1940 | compile libev with the same flags to get binary compatibility. This is |
2028 | compile libev with the same flags to get binary compatibility. This is |
1941 | obviously the case with any flags that change the ABI, but the problem is |
2029 | obviously the case with any flags that change the ABI, but the problem is |
1942 | most noticeably disabled with ev_stat and large file support. |
2030 | most noticeably displayed with ev_stat and large file support. |
1943 | |
2031 | |
1944 | The solution for this is to lobby your distribution maker to make large |
2032 | The solution for this is to lobby your distribution maker to make large |
1945 | file interfaces available by default (as e.g. FreeBSD does) and not |
2033 | file interfaces available by default (as e.g. FreeBSD does) and not |
1946 | optional. Libev cannot simply switch on large file support because it has |
2034 | optional. Libev cannot simply switch on large file support because it has |
1947 | to exchange stat structures with application programs compiled using the |
2035 | to exchange stat structures with application programs compiled using the |
1948 | default compilation environment. |
2036 | default compilation environment. |
1949 | |
2037 | |
1950 | =head3 Inotify and Kqueue |
2038 | =head3 Inotify and Kqueue |
1951 | |
2039 | |
1952 | When C<inotify (7)> support has been compiled into libev (generally |
2040 | When C<inotify (7)> support has been compiled into libev and present at |
1953 | only available with Linux 2.6.25 or above due to bugs in earlier |
2041 | runtime, it will be used to speed up change detection where possible. The |
1954 | implementations) and present at runtime, it will be used to speed up |
2042 | inotify descriptor will be created lazily when the first C<ev_stat> |
1955 | change detection where possible. The inotify descriptor will be created |
2043 | watcher is being started. |
1956 | lazily when the first C<ev_stat> watcher is being started. |
|
|
1957 | |
2044 | |
1958 | Inotify presence does not change the semantics of C<ev_stat> watchers |
2045 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1959 | except that changes might be detected earlier, and in some cases, to avoid |
2046 | except that changes might be detected earlier, and in some cases, to avoid |
1960 | making regular C<stat> calls. Even in the presence of inotify support |
2047 | making regular C<stat> calls. Even in the presence of inotify support |
1961 | there are many cases where libev has to resort to regular C<stat> polling, |
2048 | there are many cases where libev has to resort to regular C<stat> polling, |
1962 | but as long as the path exists, libev usually gets away without polling. |
2049 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2050 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2051 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2052 | xfs are fully working) libev usually gets away without polling. |
1963 | |
2053 | |
1964 | There is no support for kqueue, as apparently it cannot be used to |
2054 | There is no support for kqueue, as apparently it cannot be used to |
1965 | implement this functionality, due to the requirement of having a file |
2055 | implement this functionality, due to the requirement of having a file |
1966 | descriptor open on the object at all times, and detecting renames, unlinks |
2056 | descriptor open on the object at all times, and detecting renames, unlinks |
1967 | etc. is difficult. |
2057 | etc. is difficult. |
1968 | |
2058 | |
|
|
2059 | =head3 C<stat ()> is a synchronous operation |
|
|
2060 | |
|
|
2061 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2062 | the process. The exception are C<ev_stat> watchers - those call C<stat |
|
|
2063 | ()>, which is a synchronous operation. |
|
|
2064 | |
|
|
2065 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2066 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2067 | as the path data is usually in memory already (except when starting the |
|
|
2068 | watcher). |
|
|
2069 | |
|
|
2070 | For networked file systems, calling C<stat ()> can block an indefinite |
|
|
2071 | time due to network issues, and even under good conditions, a stat call |
|
|
2072 | often takes multiple milliseconds. |
|
|
2073 | |
|
|
2074 | Therefore, it is best to avoid using C<ev_stat> watchers on networked |
|
|
2075 | paths, although this is fully supported by libev. |
|
|
2076 | |
1969 | =head3 The special problem of stat time resolution |
2077 | =head3 The special problem of stat time resolution |
1970 | |
2078 | |
1971 | The C<stat ()> system call only supports full-second resolution portably, and |
2079 | The C<stat ()> system call only supports full-second resolution portably, |
1972 | even on systems where the resolution is higher, most file systems still |
2080 | and even on systems where the resolution is higher, most file systems |
1973 | only support whole seconds. |
2081 | still only support whole seconds. |
1974 | |
2082 | |
1975 | That means that, if the time is the only thing that changes, you can |
2083 | That means that, if the time is the only thing that changes, you can |
1976 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2084 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1977 | calls your callback, which does something. When there is another update |
2085 | calls your callback, which does something. When there is another update |
1978 | within the same second, C<ev_stat> will be unable to detect unless the |
2086 | within the same second, C<ev_stat> will be unable to detect unless the |
… | |
… | |
2121 | |
2229 | |
2122 | =head3 Watcher-Specific Functions and Data Members |
2230 | =head3 Watcher-Specific Functions and Data Members |
2123 | |
2231 | |
2124 | =over 4 |
2232 | =over 4 |
2125 | |
2233 | |
2126 | =item ev_idle_init (ev_signal *, callback) |
2234 | =item ev_idle_init (ev_idle *, callback) |
2127 | |
2235 | |
2128 | Initialises and configures the idle watcher - it has no parameters of any |
2236 | Initialises and configures the idle watcher - it has no parameters of any |
2129 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2237 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2130 | believe me. |
2238 | believe me. |
2131 | |
2239 | |
… | |
… | |
2370 | some fds have to be watched and handled very quickly (with low latency), |
2478 | some fds have to be watched and handled very quickly (with low latency), |
2371 | and even priorities and idle watchers might have too much overhead. In |
2479 | and even priorities and idle watchers might have too much overhead. In |
2372 | this case you would put all the high priority stuff in one loop and all |
2480 | this case you would put all the high priority stuff in one loop and all |
2373 | the rest in a second one, and embed the second one in the first. |
2481 | the rest in a second one, and embed the second one in the first. |
2374 | |
2482 | |
2375 | As long as the watcher is active, the callback will be invoked every time |
2483 | As long as the watcher is active, the callback will be invoked every |
2376 | there might be events pending in the embedded loop. The callback must then |
2484 | time there might be events pending in the embedded loop. The callback |
2377 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2485 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2378 | their callbacks (you could also start an idle watcher to give the embedded |
2486 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2379 | loop strictly lower priority for example). You can also set the callback |
2487 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2380 | to C<0>, in which case the embed watcher will automatically execute the |
2488 | to give the embedded loop strictly lower priority for example). |
2381 | embedded loop sweep. |
|
|
2382 | |
2489 | |
2383 | As long as the watcher is started it will automatically handle events. The |
2490 | You can also set the callback to C<0>, in which case the embed watcher |
2384 | callback will be invoked whenever some events have been handled. You can |
2491 | will automatically execute the embedded loop sweep whenever necessary. |
2385 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2386 | interested in that. |
|
|
2387 | |
2492 | |
2388 | Also, there have not currently been made special provisions for forking: |
2493 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2389 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2494 | is active, i.e., the embedded loop will automatically be forked when the |
2390 | but you will also have to stop and restart any C<ev_embed> watchers |
2495 | embedding loop forks. In other cases, the user is responsible for calling |
2391 | yourself - but you can use a fork watcher to handle this automatically, |
2496 | C<ev_loop_fork> on the embedded loop. |
2392 | and future versions of libev might do just that. |
|
|
2393 | |
2497 | |
2394 | Unfortunately, not all backends are embeddable: only the ones returned by |
2498 | Unfortunately, not all backends are embeddable: only the ones returned by |
2395 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2499 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2396 | portable one. |
2500 | portable one. |
2397 | |
2501 | |
… | |
… | |
2617 | =over 4 |
2721 | =over 4 |
2618 | |
2722 | |
2619 | =item ev_async_init (ev_async *, callback) |
2723 | =item ev_async_init (ev_async *, callback) |
2620 | |
2724 | |
2621 | Initialises and configures the async watcher - it has no parameters of any |
2725 | Initialises and configures the async watcher - it has no parameters of any |
2622 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2726 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2623 | trust me. |
2727 | trust me. |
2624 | |
2728 | |
2625 | =item ev_async_send (loop, ev_async *) |
2729 | =item ev_async_send (loop, ev_async *) |
2626 | |
2730 | |
2627 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2731 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2628 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2732 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2629 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2733 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2630 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2734 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2631 | section below on what exactly this means). |
2735 | section below on what exactly this means). |
2632 | |
2736 | |
|
|
2737 | Note that, as with other watchers in libev, multiple events might get |
|
|
2738 | compressed into a single callback invocation (another way to look at this |
|
|
2739 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
|
|
2740 | reset when the event loop detects that). |
|
|
2741 | |
2633 | This call incurs the overhead of a system call only once per loop iteration, |
2742 | This call incurs the overhead of a system call only once per event loop |
2634 | so while the overhead might be noticeable, it doesn't apply to repeated |
2743 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2635 | calls to C<ev_async_send>. |
2744 | repeated calls to C<ev_async_send> for the same event loop. |
2636 | |
2745 | |
2637 | =item bool = ev_async_pending (ev_async *) |
2746 | =item bool = ev_async_pending (ev_async *) |
2638 | |
2747 | |
2639 | Returns a non-zero value when C<ev_async_send> has been called on the |
2748 | Returns a non-zero value when C<ev_async_send> has been called on the |
2640 | watcher but the event has not yet been processed (or even noted) by the |
2749 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
2643 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2752 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2644 | the loop iterates next and checks for the watcher to have become active, |
2753 | the loop iterates next and checks for the watcher to have become active, |
2645 | it will reset the flag again. C<ev_async_pending> can be used to very |
2754 | it will reset the flag again. C<ev_async_pending> can be used to very |
2646 | quickly check whether invoking the loop might be a good idea. |
2755 | quickly check whether invoking the loop might be a good idea. |
2647 | |
2756 | |
2648 | Not that this does I<not> check whether the watcher itself is pending, only |
2757 | Not that this does I<not> check whether the watcher itself is pending, |
2649 | whether it has been requested to make this watcher pending. |
2758 | only whether it has been requested to make this watcher pending: there |
|
|
2759 | is a time window between the event loop checking and resetting the async |
|
|
2760 | notification, and the callback being invoked. |
2650 | |
2761 | |
2651 | =back |
2762 | =back |
2652 | |
2763 | |
2653 | |
2764 | |
2654 | =head1 OTHER FUNCTIONS |
2765 | =head1 OTHER FUNCTIONS |
… | |
… | |
2833 | |
2944 | |
2834 | myclass obj; |
2945 | myclass obj; |
2835 | ev::io iow; |
2946 | ev::io iow; |
2836 | iow.set <myclass, &myclass::io_cb> (&obj); |
2947 | iow.set <myclass, &myclass::io_cb> (&obj); |
2837 | |
2948 | |
|
|
2949 | =item w->set (object *) |
|
|
2950 | |
|
|
2951 | This is an B<experimental> feature that might go away in a future version. |
|
|
2952 | |
|
|
2953 | This is a variation of a method callback - leaving out the method to call |
|
|
2954 | will default the method to C<operator ()>, which makes it possible to use |
|
|
2955 | functor objects without having to manually specify the C<operator ()> all |
|
|
2956 | the time. Incidentally, you can then also leave out the template argument |
|
|
2957 | list. |
|
|
2958 | |
|
|
2959 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
2960 | int revents)>. |
|
|
2961 | |
|
|
2962 | See the method-C<set> above for more details. |
|
|
2963 | |
|
|
2964 | Example: use a functor object as callback. |
|
|
2965 | |
|
|
2966 | struct myfunctor |
|
|
2967 | { |
|
|
2968 | void operator() (ev::io &w, int revents) |
|
|
2969 | { |
|
|
2970 | ... |
|
|
2971 | } |
|
|
2972 | } |
|
|
2973 | |
|
|
2974 | myfunctor f; |
|
|
2975 | |
|
|
2976 | ev::io w; |
|
|
2977 | w.set (&f); |
|
|
2978 | |
2838 | =item w->set<function> (void *data = 0) |
2979 | =item w->set<function> (void *data = 0) |
2839 | |
2980 | |
2840 | Also sets a callback, but uses a static method or plain function as |
2981 | Also sets a callback, but uses a static method or plain function as |
2841 | callback. The optional C<data> argument will be stored in the watcher's |
2982 | callback. The optional C<data> argument will be stored in the watcher's |
2842 | C<data> member and is free for you to use. |
2983 | C<data> member and is free for you to use. |
… | |
… | |
2928 | L<http://software.schmorp.de/pkg/EV>. |
3069 | L<http://software.schmorp.de/pkg/EV>. |
2929 | |
3070 | |
2930 | =item Python |
3071 | =item Python |
2931 | |
3072 | |
2932 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
3073 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
2933 | seems to be quite complete and well-documented. Note, however, that the |
3074 | seems to be quite complete and well-documented. |
2934 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2935 | for everybody else, and therefore, should never be applied in an installed |
|
|
2936 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2937 | libev). |
|
|
2938 | |
3075 | |
2939 | =item Ruby |
3076 | =item Ruby |
2940 | |
3077 | |
2941 | Tony Arcieri has written a ruby extension that offers access to a subset |
3078 | Tony Arcieri has written a ruby extension that offers access to a subset |
2942 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3079 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2943 | more on top of it. It can be found via gem servers. Its homepage is at |
3080 | more on top of it. It can be found via gem servers. Its homepage is at |
2944 | L<http://rev.rubyforge.org/>. |
3081 | L<http://rev.rubyforge.org/>. |
2945 | |
3082 | |
|
|
3083 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3084 | makes rev work even on mingw. |
|
|
3085 | |
|
|
3086 | =item Haskell |
|
|
3087 | |
|
|
3088 | A haskell binding to libev is available at |
|
|
3089 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
|
|
3090 | |
2946 | =item D |
3091 | =item D |
2947 | |
3092 | |
2948 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3093 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2949 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3094 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
|
|
3095 | |
|
|
3096 | =item Ocaml |
|
|
3097 | |
|
|
3098 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3099 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
2950 | |
3100 | |
2951 | =back |
3101 | =back |
2952 | |
3102 | |
2953 | |
3103 | |
2954 | =head1 MACRO MAGIC |
3104 | =head1 MACRO MAGIC |
… | |
… | |
3055 | |
3205 | |
3056 | #define EV_STANDALONE 1 |
3206 | #define EV_STANDALONE 1 |
3057 | #include "ev.h" |
3207 | #include "ev.h" |
3058 | |
3208 | |
3059 | Both header files and implementation files can be compiled with a C++ |
3209 | Both header files and implementation files can be compiled with a C++ |
3060 | compiler (at least, thats a stated goal, and breakage will be treated |
3210 | compiler (at least, that's a stated goal, and breakage will be treated |
3061 | as a bug). |
3211 | as a bug). |
3062 | |
3212 | |
3063 | You need the following files in your source tree, or in a directory |
3213 | You need the following files in your source tree, or in a directory |
3064 | in your include path (e.g. in libev/ when using -Ilibev): |
3214 | in your include path (e.g. in libev/ when using -Ilibev): |
3065 | |
3215 | |
… | |
… | |
3121 | keeps libev from including F<config.h>, and it also defines dummy |
3271 | keeps libev from including F<config.h>, and it also defines dummy |
3122 | implementations for some libevent functions (such as logging, which is not |
3272 | implementations for some libevent functions (such as logging, which is not |
3123 | supported). It will also not define any of the structs usually found in |
3273 | supported). It will also not define any of the structs usually found in |
3124 | F<event.h> that are not directly supported by the libev core alone. |
3274 | F<event.h> that are not directly supported by the libev core alone. |
3125 | |
3275 | |
|
|
3276 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3277 | configuration, but has to be more conservative. |
|
|
3278 | |
3126 | =item EV_USE_MONOTONIC |
3279 | =item EV_USE_MONOTONIC |
3127 | |
3280 | |
3128 | If defined to be C<1>, libev will try to detect the availability of the |
3281 | If defined to be C<1>, libev will try to detect the availability of the |
3129 | monotonic clock option at both compile time and runtime. Otherwise no use |
3282 | monotonic clock option at both compile time and runtime. Otherwise no |
3130 | of the monotonic clock option will be attempted. If you enable this, you |
3283 | use of the monotonic clock option will be attempted. If you enable this, |
3131 | usually have to link against librt or something similar. Enabling it when |
3284 | you usually have to link against librt or something similar. Enabling it |
3132 | the functionality isn't available is safe, though, although you have |
3285 | when the functionality isn't available is safe, though, although you have |
3133 | to make sure you link against any libraries where the C<clock_gettime> |
3286 | to make sure you link against any libraries where the C<clock_gettime> |
3134 | function is hiding in (often F<-lrt>). |
3287 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3135 | |
3288 | |
3136 | =item EV_USE_REALTIME |
3289 | =item EV_USE_REALTIME |
3137 | |
3290 | |
3138 | If defined to be C<1>, libev will try to detect the availability of the |
3291 | If defined to be C<1>, libev will try to detect the availability of the |
3139 | real-time clock option at compile time (and assume its availability at |
3292 | real-time clock option at compile time (and assume its availability |
3140 | runtime if successful). Otherwise no use of the real-time clock option will |
3293 | at runtime if successful). Otherwise no use of the real-time clock |
3141 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3294 | option will be attempted. This effectively replaces C<gettimeofday> |
3142 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3295 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
3143 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3296 | correctness. See the note about libraries in the description of |
|
|
3297 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3298 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3299 | |
|
|
3300 | =item EV_USE_CLOCK_SYSCALL |
|
|
3301 | |
|
|
3302 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3303 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3304 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3305 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3306 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3307 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3308 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3309 | higher, as it simplifies linking (no need for C<-lrt>). |
3144 | |
3310 | |
3145 | =item EV_USE_NANOSLEEP |
3311 | =item EV_USE_NANOSLEEP |
3146 | |
3312 | |
3147 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3313 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3148 | and will use it for delays. Otherwise it will use C<select ()>. |
3314 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3164 | |
3330 | |
3165 | =item EV_SELECT_USE_FD_SET |
3331 | =item EV_SELECT_USE_FD_SET |
3166 | |
3332 | |
3167 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3333 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3168 | structure. This is useful if libev doesn't compile due to a missing |
3334 | structure. This is useful if libev doesn't compile due to a missing |
3169 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3335 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3170 | exotic systems. This usually limits the range of file descriptors to some |
3336 | on exotic systems. This usually limits the range of file descriptors to |
3171 | low limit such as 1024 or might have other limitations (winsocket only |
3337 | some low limit such as 1024 or might have other limitations (winsocket |
3172 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3338 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3173 | influence the size of the C<fd_set> used. |
3339 | configures the maximum size of the C<fd_set>. |
3174 | |
3340 | |
3175 | =item EV_SELECT_IS_WINSOCKET |
3341 | =item EV_SELECT_IS_WINSOCKET |
3176 | |
3342 | |
3177 | When defined to C<1>, the select backend will assume that |
3343 | When defined to C<1>, the select backend will assume that |
3178 | select/socket/connect etc. don't understand file descriptors but |
3344 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3537 | loop, as long as you don't confuse yourself). The only exception is that |
3703 | loop, as long as you don't confuse yourself). The only exception is that |
3538 | you must not do this from C<ev_periodic> reschedule callbacks. |
3704 | you must not do this from C<ev_periodic> reschedule callbacks. |
3539 | |
3705 | |
3540 | Care has been taken to ensure that libev does not keep local state inside |
3706 | Care has been taken to ensure that libev does not keep local state inside |
3541 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3707 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3542 | they do not clal any callbacks. |
3708 | they do not call any callbacks. |
3543 | |
3709 | |
3544 | =head2 COMPILER WARNINGS |
3710 | =head2 COMPILER WARNINGS |
3545 | |
3711 | |
3546 | Depending on your compiler and compiler settings, you might get no or a |
3712 | Depending on your compiler and compiler settings, you might get no or a |
3547 | lot of warnings when compiling libev code. Some people are apparently |
3713 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3581 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3747 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3582 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3748 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3583 | ==2274== still reachable: 256 bytes in 1 blocks. |
3749 | ==2274== still reachable: 256 bytes in 1 blocks. |
3584 | |
3750 | |
3585 | Then there is no memory leak, just as memory accounted to global variables |
3751 | Then there is no memory leak, just as memory accounted to global variables |
3586 | is not a memleak - the memory is still being refernced, and didn't leak. |
3752 | is not a memleak - the memory is still being referenced, and didn't leak. |
3587 | |
3753 | |
3588 | Similarly, under some circumstances, valgrind might report kernel bugs |
3754 | Similarly, under some circumstances, valgrind might report kernel bugs |
3589 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3755 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3590 | although an acceptable workaround has been found here), or it might be |
3756 | although an acceptable workaround has been found here), or it might be |
3591 | confused. |
3757 | confused. |
… | |
… | |
3829 | =back |
3995 | =back |
3830 | |
3996 | |
3831 | |
3997 | |
3832 | =head1 AUTHOR |
3998 | =head1 AUTHOR |
3833 | |
3999 | |
3834 | Marc Lehmann <libev@schmorp.de>. |
4000 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3835 | |
4001 | |