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4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
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65 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
67 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
68 | watcher. |
69 | |
69 | |
70 | =head1 FEATURES |
70 | =head2 FEATURES |
71 | |
71 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
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82 | |
82 | |
83 | It also is quite fast (see this |
83 | It also is quite fast (see this |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
85 | for example). |
86 | |
86 | |
87 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
88 | |
88 | |
89 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
90 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
91 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
92 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
93 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
95 | |
95 | |
96 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
97 | |
97 | |
98 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
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115 | |
115 | |
116 | Returns the current time as libev would use it. Please note that the |
116 | Returns the current time as libev would use it. Please note that the |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
118 | you actually want to know. |
118 | you actually want to know. |
119 | |
119 | |
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120 | =item ev_sleep (ev_tstamp interval) |
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121 | |
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122 | Sleep for the given interval: The current thread will be blocked until |
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123 | either it is interrupted or the given time interval has passed. Basically |
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124 | this is a subsecond-resolution C<sleep ()>. |
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125 | |
120 | =item int ev_version_major () |
126 | =item int ev_version_major () |
121 | |
127 | |
122 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
123 | |
129 | |
124 | You can find out the major and minor ABI version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
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300 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
301 | |
307 | |
302 | This is your standard select(2) backend. Not I<completely> standard, as |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
303 | libev tries to roll its own fd_set with no limits on the number of fds, |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
304 | but if that fails, expect a fairly low limit on the number of fds when |
310 | but if that fails, expect a fairly low limit on the number of fds when |
305 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
306 | the fastest backend for a low number of fds. |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
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313 | |
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314 | To get good performance out of this backend you need a high amount of |
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315 | parallelity (most of the file descriptors should be busy). If you are |
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316 | writing a server, you should C<accept ()> in a loop to accept as many |
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317 | connections as possible during one iteration. You might also want to have |
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318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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319 | readyness notifications you get per iteration. |
307 | |
320 | |
308 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
321 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
309 | |
322 | |
310 | And this is your standard poll(2) backend. It's more complicated than |
323 | And this is your standard poll(2) backend. It's more complicated |
311 | select, but handles sparse fds better and has no artificial limit on the |
324 | than select, but handles sparse fds better and has no artificial |
312 | number of fds you can use (except it will slow down considerably with a |
325 | limit on the number of fds you can use (except it will slow down |
313 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
326 | considerably with a lot of inactive fds). It scales similarly to select, |
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327 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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328 | performance tips. |
314 | |
329 | |
315 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
316 | |
331 | |
317 | For few fds, this backend is a bit little slower than poll and select, |
332 | For few fds, this backend is a bit little slower than poll and select, |
318 | but it scales phenomenally better. While poll and select usually scale |
333 | but it scales phenomenally better. While poll and select usually scale |
319 | like O(total_fds) where n is the total number of fds (or the highest fd), |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
320 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
321 | of shortcomings, such as silently dropping events in some hard-to-detect |
336 | of shortcomings, such as silently dropping events in some hard-to-detect |
322 | cases and rewuiring a syscall per fd change, no fork support and bad |
337 | cases and rewiring a syscall per fd change, no fork support and bad |
323 | support for dup: |
338 | support for dup. |
324 | |
339 | |
325 | While stopping, setting and starting an I/O watcher in the same iteration |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
326 | will result in some caching, there is still a syscall per such incident |
341 | will result in some caching, there is still a syscall per such incident |
327 | (because the fd could point to a different file description now), so its |
342 | (because the fd could point to a different file description now), so its |
328 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
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330 | |
345 | |
331 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
332 | need to use non-blocking I/O or other means to avoid blocking when no data |
347 | need to use non-blocking I/O or other means to avoid blocking when no data |
333 | (or space) is available. |
348 | (or space) is available. |
334 | |
349 | |
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350 | Best performance from this backend is achieved by not unregistering all |
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351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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352 | keep at least one watcher active per fd at all times. |
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353 | |
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354 | While nominally embeddeble in other event loops, this feature is broken in |
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355 | all kernel versions tested so far. |
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356 | |
335 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
336 | |
358 | |
337 | Kqueue deserves special mention, as at the time of this writing, it |
359 | Kqueue deserves special mention, as at the time of this writing, it |
338 | was broken on I<all> BSDs (usually it doesn't work with anything but |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
339 | sockets and pipes, except on Darwin, where of course it's completely |
361 | with anything but sockets and pipes, except on Darwin, where of course |
340 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
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341 | is used by default there). For this reason it's not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
342 | unless you explicitly specify it explicitly in the flags (i.e. using |
363 | unless you explicitly specify it explicitly in the flags (i.e. using |
343 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
364 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
344 | system like NetBSD. |
365 | system like NetBSD. |
345 | |
366 | |
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367 | You still can embed kqueue into a normal poll or select backend and use it |
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368 | only for sockets (after having made sure that sockets work with kqueue on |
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369 | the target platform). See C<ev_embed> watchers for more info. |
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370 | |
346 | It scales in the same way as the epoll backend, but the interface to the |
371 | It scales in the same way as the epoll backend, but the interface to the |
347 | kernel is more efficient (which says nothing about its actual speed, |
372 | kernel is more efficient (which says nothing about its actual speed, of |
348 | of course). While stopping, setting and starting an I/O watcher does |
373 | course). While stopping, setting and starting an I/O watcher does never |
349 | never cause an extra syscall as with epoll, it still adds up to two event |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
350 | changes per incident, support for C<fork ()> is very bad and it drops fds |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
351 | silently in similarly hard-to-detetc cases. |
376 | drops fds silently in similarly hard-to-detect cases. |
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377 | |
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378 | This backend usually performs well under most conditions. |
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379 | |
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380 | While nominally embeddable in other event loops, this doesn't work |
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381 | everywhere, so you might need to test for this. And since it is broken |
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382 | almost everywhere, you should only use it when you have a lot of sockets |
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383 | (for which it usually works), by embedding it into another event loop |
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384 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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385 | sockets. |
352 | |
386 | |
353 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
354 | |
388 | |
355 | This is not implemented yet (and might never be). |
389 | This is not implemented yet (and might never be, unless you send me an |
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390 | implementation). According to reports, C</dev/poll> only supports sockets |
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391 | and is not embeddable, which would limit the usefulness of this backend |
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392 | immensely. |
356 | |
393 | |
357 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
358 | |
395 | |
359 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
360 | it's really slow, but it still scales very well (O(active_fds)). |
397 | it's really slow, but it still scales very well (O(active_fds)). |
361 | |
398 | |
362 | Please note that solaris event ports can deliver a lot of spurious |
399 | Please note that solaris event ports can deliver a lot of spurious |
363 | notifications, so you need to use non-blocking I/O or other means to avoid |
400 | notifications, so you need to use non-blocking I/O or other means to avoid |
364 | blocking when no data (or space) is available. |
401 | blocking when no data (or space) is available. |
365 | |
402 | |
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403 | While this backend scales well, it requires one system call per active |
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404 | file descriptor per loop iteration. For small and medium numbers of file |
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405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
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406 | might perform better. |
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407 | |
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408 | On the positive side, ignoring the spurious readyness notifications, this |
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409 | backend actually performed to specification in all tests and is fully |
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410 | embeddable, which is a rare feat among the OS-specific backends. |
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411 | |
366 | =item C<EVBACKEND_ALL> |
412 | =item C<EVBACKEND_ALL> |
367 | |
413 | |
368 | Try all backends (even potentially broken ones that wouldn't be tried |
414 | Try all backends (even potentially broken ones that wouldn't be tried |
369 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
415 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
370 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
416 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
371 | |
417 | |
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418 | It is definitely not recommended to use this flag. |
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419 | |
372 | =back |
420 | =back |
373 | |
421 | |
374 | If one or more of these are ored into the flags value, then only these |
422 | If one or more of these are ored into the flags value, then only these |
375 | backends will be tried (in the reverse order as given here). If none are |
423 | backends will be tried (in the reverse order as listed here). If none are |
376 | specified, most compiled-in backend will be tried, usually in reverse |
424 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
377 | order of their flag values :) |
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378 | |
425 | |
379 | The most typical usage is like this: |
426 | The most typical usage is like this: |
380 | |
427 | |
381 | if (!ev_default_loop (0)) |
428 | if (!ev_default_loop (0)) |
382 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
429 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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507 | usually a better approach for this kind of thing. |
554 | usually a better approach for this kind of thing. |
508 | |
555 | |
509 | Here are the gory details of what C<ev_loop> does: |
556 | Here are the gory details of what C<ev_loop> does: |
510 | |
557 | |
511 | - Before the first iteration, call any pending watchers. |
558 | - Before the first iteration, call any pending watchers. |
512 | * If there are no active watchers (reference count is zero), return. |
559 | * If EVFLAG_FORKCHECK was used, check for a fork. |
513 | - Queue all prepare watchers and then call all outstanding watchers. |
560 | - If a fork was detected, queue and call all fork watchers. |
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561 | - Queue and call all prepare watchers. |
514 | - If we have been forked, recreate the kernel state. |
562 | - If we have been forked, recreate the kernel state. |
515 | - Update the kernel state with all outstanding changes. |
563 | - Update the kernel state with all outstanding changes. |
516 | - Update the "event loop time". |
564 | - Update the "event loop time". |
517 | - Calculate for how long to block. |
565 | - Calculate for how long to sleep or block, if at all |
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566 | (active idle watchers, EVLOOP_NONBLOCK or not having |
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567 | any active watchers at all will result in not sleeping). |
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568 | - Sleep if the I/O and timer collect interval say so. |
518 | - Block the process, waiting for any events. |
569 | - Block the process, waiting for any events. |
519 | - Queue all outstanding I/O (fd) events. |
570 | - Queue all outstanding I/O (fd) events. |
520 | - Update the "event loop time" and do time jump handling. |
571 | - Update the "event loop time" and do time jump handling. |
521 | - Queue all outstanding timers. |
572 | - Queue all outstanding timers. |
522 | - Queue all outstanding periodics. |
573 | - Queue all outstanding periodics. |
523 | - If no events are pending now, queue all idle watchers. |
574 | - If no events are pending now, queue all idle watchers. |
524 | - Queue all check watchers. |
575 | - Queue all check watchers. |
525 | - Call all queued watchers in reverse order (i.e. check watchers first). |
576 | - Call all queued watchers in reverse order (i.e. check watchers first). |
526 | Signals and child watchers are implemented as I/O watchers, and will |
577 | Signals and child watchers are implemented as I/O watchers, and will |
527 | be handled here by queueing them when their watcher gets executed. |
578 | be handled here by queueing them when their watcher gets executed. |
528 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
579 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
529 | were used, return, otherwise continue with step *. |
580 | were used, or there are no active watchers, return, otherwise |
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581 | continue with step *. |
530 | |
582 | |
531 | Example: Queue some jobs and then loop until no events are outsanding |
583 | Example: Queue some jobs and then loop until no events are outstanding |
532 | anymore. |
584 | anymore. |
533 | |
585 | |
534 | ... queue jobs here, make sure they register event watchers as long |
586 | ... queue jobs here, make sure they register event watchers as long |
535 | ... as they still have work to do (even an idle watcher will do..) |
587 | ... as they still have work to do (even an idle watcher will do..) |
536 | ev_loop (my_loop, 0); |
588 | ev_loop (my_loop, 0); |
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540 | |
592 | |
541 | Can be used to make a call to C<ev_loop> return early (but only after it |
593 | Can be used to make a call to C<ev_loop> return early (but only after it |
542 | has processed all outstanding events). The C<how> argument must be either |
594 | has processed all outstanding events). The C<how> argument must be either |
543 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
595 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
544 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
596 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
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597 | |
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598 | This "unloop state" will be cleared when entering C<ev_loop> again. |
545 | |
599 | |
546 | =item ev_ref (loop) |
600 | =item ev_ref (loop) |
547 | |
601 | |
548 | =item ev_unref (loop) |
602 | =item ev_unref (loop) |
549 | |
603 | |
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554 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
608 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
555 | example, libev itself uses this for its internal signal pipe: It is not |
609 | example, libev itself uses this for its internal signal pipe: It is not |
556 | visible to the libev user and should not keep C<ev_loop> from exiting if |
610 | visible to the libev user and should not keep C<ev_loop> from exiting if |
557 | no event watchers registered by it are active. It is also an excellent |
611 | no event watchers registered by it are active. It is also an excellent |
558 | way to do this for generic recurring timers or from within third-party |
612 | way to do this for generic recurring timers or from within third-party |
559 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
613 | libraries. Just remember to I<unref after start> and I<ref before stop> |
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614 | (but only if the watcher wasn't active before, or was active before, |
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615 | respectively). |
560 | |
616 | |
561 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
617 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
562 | running when nothing else is active. |
618 | running when nothing else is active. |
563 | |
619 | |
564 | struct ev_signal exitsig; |
620 | struct ev_signal exitsig; |
… | |
… | |
568 | |
624 | |
569 | Example: For some weird reason, unregister the above signal handler again. |
625 | Example: For some weird reason, unregister the above signal handler again. |
570 | |
626 | |
571 | ev_ref (loop); |
627 | ev_ref (loop); |
572 | ev_signal_stop (loop, &exitsig); |
628 | ev_signal_stop (loop, &exitsig); |
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629 | |
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630 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
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631 | |
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632 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
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633 | |
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634 | These advanced functions influence the time that libev will spend waiting |
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635 | for events. Both are by default C<0>, meaning that libev will try to |
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636 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
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637 | |
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638 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
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639 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
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640 | increase efficiency of loop iterations. |
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641 | |
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642 | The background is that sometimes your program runs just fast enough to |
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643 | handle one (or very few) event(s) per loop iteration. While this makes |
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644 | the program responsive, it also wastes a lot of CPU time to poll for new |
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645 | events, especially with backends like C<select ()> which have a high |
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646 | overhead for the actual polling but can deliver many events at once. |
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647 | |
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648 | By setting a higher I<io collect interval> you allow libev to spend more |
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649 | time collecting I/O events, so you can handle more events per iteration, |
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650 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
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651 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
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652 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
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653 | |
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654 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
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655 | to spend more time collecting timeouts, at the expense of increased |
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656 | latency (the watcher callback will be called later). C<ev_io> watchers |
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657 | will not be affected. Setting this to a non-null value will not introduce |
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658 | any overhead in libev. |
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659 | |
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660 | Many (busy) programs can usually benefit by setting the io collect |
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661 | interval to a value near C<0.1> or so, which is often enough for |
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662 | interactive servers (of course not for games), likewise for timeouts. It |
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663 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
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664 | as this approsaches the timing granularity of most systems. |
573 | |
665 | |
574 | =back |
666 | =back |
575 | |
667 | |
576 | |
668 | |
577 | =head1 ANATOMY OF A WATCHER |
669 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
903 | In general you can register as many read and/or write event watchers per |
995 | In general you can register as many read and/or write event watchers per |
904 | fd as you want (as long as you don't confuse yourself). Setting all file |
996 | fd as you want (as long as you don't confuse yourself). Setting all file |
905 | descriptors to non-blocking mode is also usually a good idea (but not |
997 | descriptors to non-blocking mode is also usually a good idea (but not |
906 | required if you know what you are doing). |
998 | required if you know what you are doing). |
907 | |
999 | |
908 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
909 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
910 | descriptors correctly if you register interest in two or more fds pointing |
|
|
911 | to the same underlying file/socket/etc. description (that is, they share |
|
|
912 | the same underlying "file open"). |
|
|
913 | |
|
|
914 | If you must do this, then force the use of a known-to-be-good backend |
1000 | If you must do this, then force the use of a known-to-be-good backend |
915 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1001 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
916 | C<EVBACKEND_POLL>). |
1002 | C<EVBACKEND_POLL>). |
917 | |
1003 | |
918 | Another thing you have to watch out for is that it is quite easy to |
1004 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
952 | optimisations to libev. |
1038 | optimisations to libev. |
953 | |
1039 | |
954 | =head3 The special problem of dup'ed file descriptors |
1040 | =head3 The special problem of dup'ed file descriptors |
955 | |
1041 | |
956 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1042 | Some backends (e.g. epoll), cannot register events for file descriptors, |
957 | but only events for the underlying file descriptions. That menas when you |
1043 | but only events for the underlying file descriptions. That means when you |
958 | have C<dup ()>'ed file descriptors and register events for them, only one |
1044 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
959 | file descriptor might actually receive events. |
1045 | events for them, only one file descriptor might actually receive events. |
960 | |
1046 | |
961 | There is no workaorund possible except not registering events |
1047 | There is no workaround possible except not registering events |
962 | for potentially C<dup ()>'ed file descriptors or to resort to |
1048 | for potentially C<dup ()>'ed file descriptors, or to resort to |
963 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1049 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
964 | |
1050 | |
965 | =head3 The special problem of fork |
1051 | =head3 The special problem of fork |
966 | |
1052 | |
967 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1053 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
… | |
… | |
993 | =item int events [read-only] |
1079 | =item int events [read-only] |
994 | |
1080 | |
995 | The events being watched. |
1081 | The events being watched. |
996 | |
1082 | |
997 | =back |
1083 | =back |
|
|
1084 | |
|
|
1085 | =head3 Examples |
998 | |
1086 | |
999 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1087 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1000 | readable, but only once. Since it is likely line-buffered, you could |
1088 | readable, but only once. Since it is likely line-buffered, you could |
1001 | attempt to read a whole line in the callback. |
1089 | attempt to read a whole line in the callback. |
1002 | |
1090 | |
… | |
… | |
1100 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1188 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1101 | which is also when any modifications are taken into account. |
1189 | which is also when any modifications are taken into account. |
1102 | |
1190 | |
1103 | =back |
1191 | =back |
1104 | |
1192 | |
|
|
1193 | =head3 Examples |
|
|
1194 | |
1105 | Example: Create a timer that fires after 60 seconds. |
1195 | Example: Create a timer that fires after 60 seconds. |
1106 | |
1196 | |
1107 | static void |
1197 | static void |
1108 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1198 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1109 | { |
1199 | { |
… | |
… | |
1266 | When active, contains the absolute time that the watcher is supposed to |
1356 | When active, contains the absolute time that the watcher is supposed to |
1267 | trigger next. |
1357 | trigger next. |
1268 | |
1358 | |
1269 | =back |
1359 | =back |
1270 | |
1360 | |
|
|
1361 | =head3 Examples |
|
|
1362 | |
1271 | Example: Call a callback every hour, or, more precisely, whenever the |
1363 | Example: Call a callback every hour, or, more precisely, whenever the |
1272 | system clock is divisible by 3600. The callback invocation times have |
1364 | system clock is divisible by 3600. The callback invocation times have |
1273 | potentially a lot of jittering, but good long-term stability. |
1365 | potentially a lot of jittering, but good long-term stability. |
1274 | |
1366 | |
1275 | static void |
1367 | static void |
… | |
… | |
1366 | |
1458 | |
1367 | The process exit/trace status caused by C<rpid> (see your systems |
1459 | The process exit/trace status caused by C<rpid> (see your systems |
1368 | C<waitpid> and C<sys/wait.h> documentation for details). |
1460 | C<waitpid> and C<sys/wait.h> documentation for details). |
1369 | |
1461 | |
1370 | =back |
1462 | =back |
|
|
1463 | |
|
|
1464 | =head3 Examples |
1371 | |
1465 | |
1372 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1466 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1373 | |
1467 | |
1374 | static void |
1468 | static void |
1375 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1469 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1416 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1510 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1417 | to fall back to regular polling again even with inotify, but changes are |
1511 | to fall back to regular polling again even with inotify, but changes are |
1418 | usually detected immediately, and if the file exists there will be no |
1512 | usually detected immediately, and if the file exists there will be no |
1419 | polling. |
1513 | polling. |
1420 | |
1514 | |
|
|
1515 | =head3 Inotify |
|
|
1516 | |
|
|
1517 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1518 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1519 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1520 | when the first C<ev_stat> watcher is being started. |
|
|
1521 | |
|
|
1522 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1523 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1524 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1525 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1526 | |
|
|
1527 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1528 | implement this functionality, due to the requirement of having a file |
|
|
1529 | descriptor open on the object at all times). |
|
|
1530 | |
|
|
1531 | =head3 The special problem of stat time resolution |
|
|
1532 | |
|
|
1533 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1534 | even on systems where the resolution is higher, many filesystems still |
|
|
1535 | only support whole seconds. |
|
|
1536 | |
|
|
1537 | That means that, if the time is the only thing that changes, you might |
|
|
1538 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1539 | your callback, which does something. When there is another update within |
|
|
1540 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1541 | |
|
|
1542 | The solution to this is to delay acting on a change for a second (or till |
|
|
1543 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1544 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1545 | is added to work around small timing inconsistencies of some operating |
|
|
1546 | systems. |
|
|
1547 | |
1421 | =head3 Watcher-Specific Functions and Data Members |
1548 | =head3 Watcher-Specific Functions and Data Members |
1422 | |
1549 | |
1423 | =over 4 |
1550 | =over 4 |
1424 | |
1551 | |
1425 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1552 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1462 | =item const char *path [read-only] |
1589 | =item const char *path [read-only] |
1463 | |
1590 | |
1464 | The filesystem path that is being watched. |
1591 | The filesystem path that is being watched. |
1465 | |
1592 | |
1466 | =back |
1593 | =back |
|
|
1594 | |
|
|
1595 | =head3 Examples |
1467 | |
1596 | |
1468 | Example: Watch C</etc/passwd> for attribute changes. |
1597 | Example: Watch C</etc/passwd> for attribute changes. |
1469 | |
1598 | |
1470 | static void |
1599 | static void |
1471 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1600 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1484 | } |
1613 | } |
1485 | |
1614 | |
1486 | ... |
1615 | ... |
1487 | ev_stat passwd; |
1616 | ev_stat passwd; |
1488 | |
1617 | |
1489 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1618 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1490 | ev_stat_start (loop, &passwd); |
1619 | ev_stat_start (loop, &passwd); |
|
|
1620 | |
|
|
1621 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1622 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1623 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1624 | C<ev_timer> callback invocation). |
|
|
1625 | |
|
|
1626 | static ev_stat passwd; |
|
|
1627 | static ev_timer timer; |
|
|
1628 | |
|
|
1629 | static void |
|
|
1630 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1631 | { |
|
|
1632 | ev_timer_stop (EV_A_ w); |
|
|
1633 | |
|
|
1634 | /* now it's one second after the most recent passwd change */ |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | static void |
|
|
1638 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1639 | { |
|
|
1640 | /* reset the one-second timer */ |
|
|
1641 | ev_timer_again (EV_A_ &timer); |
|
|
1642 | } |
|
|
1643 | |
|
|
1644 | ... |
|
|
1645 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1646 | ev_stat_start (loop, &passwd); |
|
|
1647 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1491 | |
1648 | |
1492 | |
1649 | |
1493 | =head2 C<ev_idle> - when you've got nothing better to do... |
1650 | =head2 C<ev_idle> - when you've got nothing better to do... |
1494 | |
1651 | |
1495 | Idle watchers trigger events when no other events of the same or higher |
1652 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1520 | Initialises and configures the idle watcher - it has no parameters of any |
1677 | Initialises and configures the idle watcher - it has no parameters of any |
1521 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1678 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1522 | believe me. |
1679 | believe me. |
1523 | |
1680 | |
1524 | =back |
1681 | =back |
|
|
1682 | |
|
|
1683 | =head3 Examples |
1525 | |
1684 | |
1526 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1685 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1527 | callback, free it. Also, use no error checking, as usual. |
1686 | callback, free it. Also, use no error checking, as usual. |
1528 | |
1687 | |
1529 | static void |
1688 | static void |
… | |
… | |
1581 | |
1740 | |
1582 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1741 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1583 | priority, to ensure that they are being run before any other watchers |
1742 | priority, to ensure that they are being run before any other watchers |
1584 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1743 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1585 | too) should not activate ("feed") events into libev. While libev fully |
1744 | too) should not activate ("feed") events into libev. While libev fully |
1586 | supports this, they will be called before other C<ev_check> watchers did |
1745 | supports this, they will be called before other C<ev_check> watchers |
1587 | their job. As C<ev_check> watchers are often used to embed other event |
1746 | did their job. As C<ev_check> watchers are often used to embed other |
1588 | loops those other event loops might be in an unusable state until their |
1747 | (non-libev) event loops those other event loops might be in an unusable |
1589 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1748 | state until their C<ev_check> watcher ran (always remind yourself to |
1590 | others). |
1749 | coexist peacefully with others). |
1591 | |
1750 | |
1592 | =head3 Watcher-Specific Functions and Data Members |
1751 | =head3 Watcher-Specific Functions and Data Members |
1593 | |
1752 | |
1594 | =over 4 |
1753 | =over 4 |
1595 | |
1754 | |
… | |
… | |
1600 | Initialises and configures the prepare or check watcher - they have no |
1759 | Initialises and configures the prepare or check watcher - they have no |
1601 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1760 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1602 | macros, but using them is utterly, utterly and completely pointless. |
1761 | macros, but using them is utterly, utterly and completely pointless. |
1603 | |
1762 | |
1604 | =back |
1763 | =back |
|
|
1764 | |
|
|
1765 | =head3 Examples |
1605 | |
1766 | |
1606 | There are a number of principal ways to embed other event loops or modules |
1767 | There are a number of principal ways to embed other event loops or modules |
1607 | into libev. Here are some ideas on how to include libadns into libev |
1768 | into libev. Here are some ideas on how to include libadns into libev |
1608 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1769 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1609 | use for an actually working example. Another Perl module named C<EV::Glib> |
1770 | use for an actually working example. Another Perl module named C<EV::Glib> |
… | |
… | |
1734 | =head2 C<ev_embed> - when one backend isn't enough... |
1895 | =head2 C<ev_embed> - when one backend isn't enough... |
1735 | |
1896 | |
1736 | This is a rather advanced watcher type that lets you embed one event loop |
1897 | This is a rather advanced watcher type that lets you embed one event loop |
1737 | into another (currently only C<ev_io> events are supported in the embedded |
1898 | into another (currently only C<ev_io> events are supported in the embedded |
1738 | loop, other types of watchers might be handled in a delayed or incorrect |
1899 | loop, other types of watchers might be handled in a delayed or incorrect |
1739 | fashion and must not be used). (See portability notes, below). |
1900 | fashion and must not be used). |
1740 | |
1901 | |
1741 | There are primarily two reasons you would want that: work around bugs and |
1902 | There are primarily two reasons you would want that: work around bugs and |
1742 | prioritise I/O. |
1903 | prioritise I/O. |
1743 | |
1904 | |
1744 | As an example for a bug workaround, the kqueue backend might only support |
1905 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1778 | portable one. |
1939 | portable one. |
1779 | |
1940 | |
1780 | So when you want to use this feature you will always have to be prepared |
1941 | So when you want to use this feature you will always have to be prepared |
1781 | that you cannot get an embeddable loop. The recommended way to get around |
1942 | that you cannot get an embeddable loop. The recommended way to get around |
1782 | this is to have a separate variables for your embeddable loop, try to |
1943 | this is to have a separate variables for your embeddable loop, try to |
1783 | create it, and if that fails, use the normal loop for everything: |
1944 | create it, and if that fails, use the normal loop for everything. |
|
|
1945 | |
|
|
1946 | =head3 Watcher-Specific Functions and Data Members |
|
|
1947 | |
|
|
1948 | =over 4 |
|
|
1949 | |
|
|
1950 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1951 | |
|
|
1952 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1953 | |
|
|
1954 | Configures the watcher to embed the given loop, which must be |
|
|
1955 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1956 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1957 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1958 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1959 | |
|
|
1960 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1961 | |
|
|
1962 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1963 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1964 | apropriate way for embedded loops. |
|
|
1965 | |
|
|
1966 | =item struct ev_loop *other [read-only] |
|
|
1967 | |
|
|
1968 | The embedded event loop. |
|
|
1969 | |
|
|
1970 | =back |
|
|
1971 | |
|
|
1972 | =head3 Examples |
|
|
1973 | |
|
|
1974 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1975 | event loop. If that is not possible, use the default loop. The default |
|
|
1976 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1977 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1978 | used). |
1784 | |
1979 | |
1785 | struct ev_loop *loop_hi = ev_default_init (0); |
1980 | struct ev_loop *loop_hi = ev_default_init (0); |
1786 | struct ev_loop *loop_lo = 0; |
1981 | struct ev_loop *loop_lo = 0; |
1787 | struct ev_embed embed; |
1982 | struct ev_embed embed; |
1788 | |
1983 | |
… | |
… | |
1799 | ev_embed_start (loop_hi, &embed); |
1994 | ev_embed_start (loop_hi, &embed); |
1800 | } |
1995 | } |
1801 | else |
1996 | else |
1802 | loop_lo = loop_hi; |
1997 | loop_lo = loop_hi; |
1803 | |
1998 | |
1804 | =head2 Portability notes |
1999 | Example: Check if kqueue is available but not recommended and create |
|
|
2000 | a kqueue backend for use with sockets (which usually work with any |
|
|
2001 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2002 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1805 | |
2003 | |
1806 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
2004 | struct ev_loop *loop = ev_default_init (0); |
1807 | tried, in various ways. Usually the embedded event loop will simply never |
2005 | struct ev_loop *loop_socket = 0; |
1808 | receive events, sometimes it will only trigger a few times, sometimes in a |
2006 | struct ev_embed embed; |
1809 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
2007 | |
1810 | will always eport the epoll fd as ready, even when no events are pending. |
2008 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2009 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2010 | { |
|
|
2011 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2012 | ev_embed_start (loop, &embed); |
|
|
2013 | } |
1811 | |
2014 | |
1812 | While libev allows embedding these backends (they are contained in |
2015 | if (!loop_socket) |
1813 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
2016 | loop_socket = loop; |
1814 | work. |
|
|
1815 | |
2017 | |
1816 | When in doubt, create a dynamic event loop forced to use sockets (this |
2018 | // now use loop_socket for all sockets, and loop for everything else |
1817 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1818 | your main event loop. |
|
|
1819 | |
|
|
1820 | =head3 Watcher-Specific Functions and Data Members |
|
|
1821 | |
|
|
1822 | =over 4 |
|
|
1823 | |
|
|
1824 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1825 | |
|
|
1826 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1827 | |
|
|
1828 | Configures the watcher to embed the given loop, which must be |
|
|
1829 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1830 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1831 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1832 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1833 | |
|
|
1834 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1835 | |
|
|
1836 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1837 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1838 | apropriate way for embedded loops. |
|
|
1839 | |
|
|
1840 | =item struct ev_loop *other [read-only] |
|
|
1841 | |
|
|
1842 | The embedded event loop. |
|
|
1843 | |
|
|
1844 | =back |
|
|
1845 | |
2019 | |
1846 | |
2020 | |
1847 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2021 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1848 | |
2022 | |
1849 | Fork watchers are called when a C<fork ()> was detected (usually because |
2023 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2297 | runtime if successful). Otherwise no use of the realtime clock option will |
2471 | runtime if successful). Otherwise no use of the realtime clock option will |
2298 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2472 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2299 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2473 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2300 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2474 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2301 | |
2475 | |
|
|
2476 | =item EV_USE_NANOSLEEP |
|
|
2477 | |
|
|
2478 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2479 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2480 | |
2302 | =item EV_USE_SELECT |
2481 | =item EV_USE_SELECT |
2303 | |
2482 | |
2304 | If undefined or defined to be C<1>, libev will compile in support for the |
2483 | If undefined or defined to be C<1>, libev will compile in support for the |
2305 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2484 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2306 | other method takes over, select will be it. Otherwise the select backend |
2485 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2323 | wants osf handles on win32 (this is the case when the select to |
2502 | wants osf handles on win32 (this is the case when the select to |
2324 | be used is the winsock select). This means that it will call |
2503 | be used is the winsock select). This means that it will call |
2325 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2504 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2326 | it is assumed that all these functions actually work on fds, even |
2505 | it is assumed that all these functions actually work on fds, even |
2327 | on win32. Should not be defined on non-win32 platforms. |
2506 | on win32. Should not be defined on non-win32 platforms. |
|
|
2507 | |
|
|
2508 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2509 | |
|
|
2510 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2511 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2512 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2513 | correct. In some cases, programs use their own file descriptor management, |
|
|
2514 | in which case they can provide this function to map fds to socket handles. |
2328 | |
2515 | |
2329 | =item EV_USE_POLL |
2516 | =item EV_USE_POLL |
2330 | |
2517 | |
2331 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2518 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2332 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2519 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2369 | be detected at runtime. |
2556 | be detected at runtime. |
2370 | |
2557 | |
2371 | =item EV_H |
2558 | =item EV_H |
2372 | |
2559 | |
2373 | The name of the F<ev.h> header file used to include it. The default if |
2560 | The name of the F<ev.h> header file used to include it. The default if |
2374 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2561 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2375 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2562 | virtually rename the F<ev.h> header file in case of conflicts. |
2376 | |
2563 | |
2377 | =item EV_CONFIG_H |
2564 | =item EV_CONFIG_H |
2378 | |
2565 | |
2379 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2566 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2380 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2567 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2381 | C<EV_H>, above. |
2568 | C<EV_H>, above. |
2382 | |
2569 | |
2383 | =item EV_EVENT_H |
2570 | =item EV_EVENT_H |
2384 | |
2571 | |
2385 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2572 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2386 | of how the F<event.h> header can be found. |
2573 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2387 | |
2574 | |
2388 | =item EV_PROTOTYPES |
2575 | =item EV_PROTOTYPES |
2389 | |
2576 | |
2390 | If defined to be C<0>, then F<ev.h> will not define any function |
2577 | If defined to be C<0>, then F<ev.h> will not define any function |
2391 | prototypes, but still define all the structs and other symbols. This is |
2578 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2457 | than enough. If you need to manage thousands of children you might want to |
2644 | than enough. If you need to manage thousands of children you might want to |
2458 | increase this value (I<must> be a power of two). |
2645 | increase this value (I<must> be a power of two). |
2459 | |
2646 | |
2460 | =item EV_INOTIFY_HASHSIZE |
2647 | =item EV_INOTIFY_HASHSIZE |
2461 | |
2648 | |
2462 | C<ev_staz> watchers use a small hash table to distribute workload by |
2649 | C<ev_stat> watchers use a small hash table to distribute workload by |
2463 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2650 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2464 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2651 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2465 | watchers you might want to increase this value (I<must> be a power of |
2652 | watchers you might want to increase this value (I<must> be a power of |
2466 | two). |
2653 | two). |
2467 | |
2654 | |
… | |
… | |
2563 | |
2750 | |
2564 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2751 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2565 | |
2752 | |
2566 | This means that, when you have a watcher that triggers in one hour and |
2753 | This means that, when you have a watcher that triggers in one hour and |
2567 | there are 100 watchers that would trigger before that then inserting will |
2754 | there are 100 watchers that would trigger before that then inserting will |
2568 | have to skip those 100 watchers. |
2755 | have to skip roughly seven (C<ld 100>) of these watchers. |
2569 | |
2756 | |
2570 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2757 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2571 | |
2758 | |
2572 | That means that for changing a timer costs less than removing/adding them |
2759 | That means that changing a timer costs less than removing/adding them |
2573 | as only the relative motion in the event queue has to be paid for. |
2760 | as only the relative motion in the event queue has to be paid for. |
2574 | |
2761 | |
2575 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2762 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2576 | |
2763 | |
2577 | These just add the watcher into an array or at the head of a list. |
2764 | These just add the watcher into an array or at the head of a list. |
|
|
2765 | |
2578 | =item Stopping check/prepare/idle watchers: O(1) |
2766 | =item Stopping check/prepare/idle watchers: O(1) |
2579 | |
2767 | |
2580 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2768 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2581 | |
2769 | |
2582 | These watchers are stored in lists then need to be walked to find the |
2770 | These watchers are stored in lists then need to be walked to find the |
2583 | correct watcher to remove. The lists are usually short (you don't usually |
2771 | correct watcher to remove. The lists are usually short (you don't usually |
2584 | have many watchers waiting for the same fd or signal). |
2772 | have many watchers waiting for the same fd or signal). |
2585 | |
2773 | |
2586 | =item Finding the next timer per loop iteration: O(1) |
2774 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2775 | |
|
|
2776 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2777 | beginning of the storage array. |
2587 | |
2778 | |
2588 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2779 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2589 | |
2780 | |
2590 | A change means an I/O watcher gets started or stopped, which requires |
2781 | A change means an I/O watcher gets started or stopped, which requires |
2591 | libev to recalculate its status (and possibly tell the kernel). |
2782 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2783 | on backend and wether C<ev_io_set> was used). |
2592 | |
2784 | |
2593 | =item Activating one watcher: O(1) |
2785 | =item Activating one watcher (putting it into the pending state): O(1) |
2594 | |
2786 | |
2595 | =item Priority handling: O(number_of_priorities) |
2787 | =item Priority handling: O(number_of_priorities) |
2596 | |
2788 | |
2597 | Priorities are implemented by allocating some space for each |
2789 | Priorities are implemented by allocating some space for each |
2598 | priority. When doing priority-based operations, libev usually has to |
2790 | priority. When doing priority-based operations, libev usually has to |
2599 | linearly search all the priorities. |
2791 | linearly search all the priorities, but starting/stopping and activating |
|
|
2792 | watchers becomes O(1) w.r.t. prioritiy handling. |
2600 | |
2793 | |
2601 | =back |
2794 | =back |
2602 | |
2795 | |
2603 | |
2796 | |
|
|
2797 | =head1 Win32 platform limitations and workarounds |
|
|
2798 | |
|
|
2799 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2800 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2801 | model. Libev still offers limited functionality on this platform in |
|
|
2802 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2803 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2804 | e.g. cygwin. |
|
|
2805 | |
|
|
2806 | There is no supported compilation method available on windows except |
|
|
2807 | embedding it into other applications. |
|
|
2808 | |
|
|
2809 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2810 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2811 | recommended (and not reasonable). If your program needs to use more than |
|
|
2812 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2813 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2814 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2815 | |
|
|
2816 | =over 4 |
|
|
2817 | |
|
|
2818 | =item The winsocket select function |
|
|
2819 | |
|
|
2820 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2821 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2822 | very inefficient, and also requires a mapping from file descriptors |
|
|
2823 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2824 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2825 | symbols for more info. |
|
|
2826 | |
|
|
2827 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2828 | libraries and raw winsocket select is: |
|
|
2829 | |
|
|
2830 | #define EV_USE_SELECT 1 |
|
|
2831 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2832 | |
|
|
2833 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2834 | complexity in the O(n²) range when using win32. |
|
|
2835 | |
|
|
2836 | =item Limited number of file descriptors |
|
|
2837 | |
|
|
2838 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2839 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2840 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2841 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2842 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2843 | |
|
|
2844 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2845 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2846 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2847 | select emulation on windows). |
|
|
2848 | |
|
|
2849 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2850 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2851 | or something like this inside microsoft). You can increase this by calling |
|
|
2852 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2853 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2854 | libraries. |
|
|
2855 | |
|
|
2856 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2857 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2858 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2859 | calling select (O(n²)) will likely make this unworkable. |
|
|
2860 | |
|
|
2861 | =back |
|
|
2862 | |
|
|
2863 | |
2604 | =head1 AUTHOR |
2864 | =head1 AUTHOR |
2605 | |
2865 | |
2606 | Marc Lehmann <libev@schmorp.de>. |
2866 | Marc Lehmann <libev@schmorp.de>. |
2607 | |
2867 | |