… | |
… | |
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; |
… | |
… | |
53 | The newest version of this document is also available as a html-formatted |
53 | The newest version of this document is also available as a html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
54 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
56 | |
56 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
58 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occurring), and it will manage |
59 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
60 | |
60 | |
61 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
62 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
63 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
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 |
… | |
… | |
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 |
102 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
103 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
|
|
104 | component C<stamp> might indicate, it is also used for time differences |
|
|
105 | throughout libev. |
104 | |
106 | |
105 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
106 | |
108 | |
107 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
108 | library in any way. |
110 | library in any way. |
… | |
… | |
113 | |
115 | |
114 | 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 |
115 | 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 |
116 | you actually want to know. |
118 | you actually want to know. |
117 | |
119 | |
|
|
120 | =item ev_sleep (ev_tstamp interval) |
|
|
121 | |
|
|
122 | Sleep for the given interval: The current thread will be blocked until |
|
|
123 | either it is interrupted or the given time interval has passed. Basically |
|
|
124 | this is a subsecond-resolution C<sleep ()>. |
|
|
125 | |
118 | =item int ev_version_major () |
126 | =item int ev_version_major () |
119 | |
127 | |
120 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
121 | |
129 | |
122 | You can find out the major and minor API/ABI version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
123 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
124 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
126 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
127 | |
135 | |
128 | These version numbers refer to the API and ABI version of the library, not |
136 | These version numbers refer to the ABI version of the library, not the |
129 | the release version. |
137 | release version. |
130 | |
138 | |
131 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
132 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
133 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
134 | not a problem. |
142 | not a problem. |
… | |
… | |
298 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
299 | |
307 | |
300 | 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 |
301 | 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, |
302 | 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 |
303 | 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 |
304 | the fastest backend for a low number of fds. |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
313 | |
|
|
314 | To get good performance out of this backend you need a high amount of |
|
|
315 | parallelity (most of the file descriptors should be busy). If you are |
|
|
316 | writing a server, you should C<accept ()> in a loop to accept as many |
|
|
317 | connections as possible during one iteration. You might also want to have |
|
|
318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
|
|
319 | readyness notifications you get per iteration. |
305 | |
320 | |
306 | =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) |
307 | |
322 | |
308 | 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 |
309 | 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 |
310 | 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 |
311 | 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, |
|
|
327 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
|
|
328 | performance tips. |
312 | |
329 | |
313 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
314 | |
331 | |
315 | 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, |
316 | but it scales phenomenally better. While poll and select usually scale like |
333 | but it scales phenomenally better. While poll and select usually scale |
317 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
318 | either O(1) or O(active_fds). |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
336 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
337 | cases and rewiring a syscall per fd change, no fork support and bad |
|
|
338 | support for dup. |
319 | |
339 | |
320 | While stopping and starting an I/O watcher in the same iteration will |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
321 | 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 |
322 | (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 |
323 | best to avoid that. Also, dup()ed file descriptors might not work very |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
324 | well if you register events for both fds. |
344 | very well if you register events for both fds. |
325 | |
345 | |
326 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
327 | 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 |
328 | (or space) is available. |
348 | (or space) is available. |
329 | |
349 | |
|
|
350 | Best performance from this backend is achieved by not unregistering all |
|
|
351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
352 | keep at least one watcher active per fd at all times. |
|
|
353 | |
|
|
354 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
355 | all kernel versions tested so far. |
|
|
356 | |
330 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
331 | |
358 | |
332 | 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 |
333 | was broken on all BSDs except NetBSD (usually it doesn't work with |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
334 | anything but sockets and pipes, except on Darwin, where of course its |
361 | with anything but sockets and pipes, except on Darwin, where of course |
335 | completely useless). For this reason its not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
336 | 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 |
337 | C<EVBACKEND_KQUEUE>). |
364 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
365 | system like NetBSD. |
|
|
366 | |
|
|
367 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
368 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
369 | the target platform). See C<ev_embed> watchers for more info. |
338 | |
370 | |
339 | 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 |
340 | kernel is more efficient (which says nothing about its actual speed, of |
372 | kernel is more efficient (which says nothing about its actual speed, of |
341 | course). While starting and stopping an I/O watcher does not cause an |
373 | course). While stopping, setting and starting an I/O watcher does never |
342 | extra syscall as with epoll, it still adds up to four event changes per |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
343 | incident, so its best to avoid that. |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
|
|
376 | drops fds silently in similarly hard-to-detect cases. |
|
|
377 | |
|
|
378 | This backend usually performs well under most conditions. |
|
|
379 | |
|
|
380 | While nominally embeddable in other event loops, this doesn't work |
|
|
381 | everywhere, so you might need to test for this. And since it is broken |
|
|
382 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
383 | (for which it usually works), by embedding it into another event loop |
|
|
384 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
|
|
385 | sockets. |
344 | |
386 | |
345 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
346 | |
388 | |
347 | This is not implemented yet (and might never be). |
389 | This is not implemented yet (and might never be, unless you send me an |
|
|
390 | implementation). According to reports, C</dev/poll> only supports sockets |
|
|
391 | and is not embeddable, which would limit the usefulness of this backend |
|
|
392 | immensely. |
348 | |
393 | |
349 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
350 | |
395 | |
351 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
352 | 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)). |
353 | |
398 | |
354 | Please note that solaris ports can result in a lot of spurious |
399 | Please note that solaris event ports can deliver a lot of spurious |
355 | 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 |
356 | blocking when no data (or space) is available. |
401 | blocking when no data (or space) is available. |
|
|
402 | |
|
|
403 | While this backend scales well, it requires one system call per active |
|
|
404 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
|
406 | might perform better. |
357 | |
407 | |
358 | =item C<EVBACKEND_ALL> |
408 | =item C<EVBACKEND_ALL> |
359 | |
409 | |
360 | Try all backends (even potentially broken ones that wouldn't be tried |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
361 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
362 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
|
413 | |
|
|
414 | It is definitely not recommended to use this flag. |
363 | |
415 | |
364 | =back |
416 | =back |
365 | |
417 | |
366 | If one or more of these are ored into the flags value, then only these |
418 | If one or more of these are ored into the flags value, then only these |
367 | backends will be tried (in the reverse order as given here). If none are |
419 | backends will be tried (in the reverse order as given here). If none are |
… | |
… | |
402 | Destroys the default loop again (frees all memory and kernel state |
454 | Destroys the default loop again (frees all memory and kernel state |
403 | etc.). None of the active event watchers will be stopped in the normal |
455 | etc.). None of the active event watchers will be stopped in the normal |
404 | sense, so e.g. C<ev_is_active> might still return true. It is your |
456 | sense, so e.g. C<ev_is_active> might still return true. It is your |
405 | responsibility to either stop all watchers cleanly yoursef I<before> |
457 | responsibility to either stop all watchers cleanly yoursef I<before> |
406 | calling this function, or cope with the fact afterwards (which is usually |
458 | calling this function, or cope with the fact afterwards (which is usually |
407 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
459 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
408 | for example). |
460 | for example). |
|
|
461 | |
|
|
462 | Note that certain global state, such as signal state, will not be freed by |
|
|
463 | this function, and related watchers (such as signal and child watchers) |
|
|
464 | would need to be stopped manually. |
|
|
465 | |
|
|
466 | In general it is not advisable to call this function except in the |
|
|
467 | rare occasion where you really need to free e.g. the signal handling |
|
|
468 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
469 | C<ev_loop_new> and C<ev_loop_destroy>). |
409 | |
470 | |
410 | =item ev_loop_destroy (loop) |
471 | =item ev_loop_destroy (loop) |
411 | |
472 | |
412 | Like C<ev_default_destroy>, but destroys an event loop created by an |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
413 | earlier call to C<ev_loop_new>. |
474 | earlier call to C<ev_loop_new>. |
… | |
… | |
458 | |
519 | |
459 | Returns the current "event loop time", which is the time the event loop |
520 | Returns the current "event loop time", which is the time the event loop |
460 | received events and started processing them. This timestamp does not |
521 | received events and started processing them. This timestamp does not |
461 | change as long as callbacks are being processed, and this is also the base |
522 | change as long as callbacks are being processed, and this is also the base |
462 | time used for relative timers. You can treat it as the timestamp of the |
523 | time used for relative timers. You can treat it as the timestamp of the |
463 | event occuring (or more correctly, libev finding out about it). |
524 | event occurring (or more correctly, libev finding out about it). |
464 | |
525 | |
465 | =item ev_loop (loop, int flags) |
526 | =item ev_loop (loop, int flags) |
466 | |
527 | |
467 | Finally, this is it, the event handler. This function usually is called |
528 | Finally, this is it, the event handler. This function usually is called |
468 | after you initialised all your watchers and you want to start handling |
529 | after you initialised all your watchers and you want to start handling |
… | |
… | |
552 | Example: For some weird reason, unregister the above signal handler again. |
613 | Example: For some weird reason, unregister the above signal handler again. |
553 | |
614 | |
554 | ev_ref (loop); |
615 | ev_ref (loop); |
555 | ev_signal_stop (loop, &exitsig); |
616 | ev_signal_stop (loop, &exitsig); |
556 | |
617 | |
|
|
618 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
619 | |
|
|
620 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
621 | |
|
|
622 | These advanced functions influence the time that libev will spend waiting |
|
|
623 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
624 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
625 | |
|
|
626 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
627 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
628 | increase efficiency of loop iterations. |
|
|
629 | |
|
|
630 | The background is that sometimes your program runs just fast enough to |
|
|
631 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
632 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
633 | events, especially with backends like C<select ()> which have a high |
|
|
634 | overhead for the actual polling but can deliver many events at once. |
|
|
635 | |
|
|
636 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
637 | time collecting I/O events, so you can handle more events per iteration, |
|
|
638 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
639 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
640 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
641 | |
|
|
642 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
643 | to spend more time collecting timeouts, at the expense of increased |
|
|
644 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
645 | will not be affected. Setting this to a non-null value will not introduce |
|
|
646 | any overhead in libev. |
|
|
647 | |
|
|
648 | Many (busy) programs can usually benefit by setting the io collect |
|
|
649 | interval to a value near C<0.1> or so, which is often enough for |
|
|
650 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
651 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
652 | as this approsaches the timing granularity of most systems. |
|
|
653 | |
557 | =back |
654 | =back |
558 | |
655 | |
559 | |
656 | |
560 | =head1 ANATOMY OF A WATCHER |
657 | =head1 ANATOMY OF A WATCHER |
561 | |
658 | |
… | |
… | |
911 | play around with an Xlib connection), then you have to seperately re-test |
1008 | play around with an Xlib connection), then you have to seperately re-test |
912 | whether a file descriptor is really ready with a known-to-be good interface |
1009 | whether a file descriptor is really ready with a known-to-be good interface |
913 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1010 | such as poll (fortunately in our Xlib example, Xlib already does this on |
914 | its own, so its quite safe to use). |
1011 | its own, so its quite safe to use). |
915 | |
1012 | |
|
|
1013 | =head3 The special problem of disappearing file descriptors |
|
|
1014 | |
|
|
1015 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1016 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1017 | such as C<dup>). The reason is that you register interest in some file |
|
|
1018 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1019 | this interest. If another file descriptor with the same number then is |
|
|
1020 | registered with libev, there is no efficient way to see that this is, in |
|
|
1021 | fact, a different file descriptor. |
|
|
1022 | |
|
|
1023 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1024 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1025 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1026 | it is assumed that the file descriptor stays the same. That means that |
|
|
1027 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1028 | descriptor even if the file descriptor number itself did not change. |
|
|
1029 | |
|
|
1030 | This is how one would do it normally anyway, the important point is that |
|
|
1031 | the libev application should not optimise around libev but should leave |
|
|
1032 | optimisations to libev. |
|
|
1033 | |
|
|
1034 | =head3 The special problem of dup'ed file descriptors |
|
|
1035 | |
|
|
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1037 | but only events for the underlying file descriptions. That means when you |
|
|
1038 | have C<dup ()>'ed file descriptors and register events for them, only one |
|
|
1039 | file descriptor might actually receive events. |
|
|
1040 | |
|
|
1041 | There is no workaround possible except not registering events |
|
|
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1044 | |
|
|
1045 | =head3 The special problem of fork |
|
|
1046 | |
|
|
1047 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1048 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1049 | it in the child. |
|
|
1050 | |
|
|
1051 | To support fork in your programs, you either have to call |
|
|
1052 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1053 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1054 | C<EVBACKEND_POLL>. |
|
|
1055 | |
|
|
1056 | |
|
|
1057 | =head3 Watcher-Specific Functions |
|
|
1058 | |
916 | =over 4 |
1059 | =over 4 |
917 | |
1060 | |
918 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1061 | =item ev_io_init (ev_io *, callback, int fd, int events) |
919 | |
1062 | |
920 | =item ev_io_set (ev_io *, int fd, int events) |
1063 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
972 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1115 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
973 | |
1116 | |
974 | The callback is guarenteed to be invoked only when its timeout has passed, |
1117 | The callback is guarenteed to be invoked only when its timeout has passed, |
975 | but if multiple timers become ready during the same loop iteration then |
1118 | but if multiple timers become ready during the same loop iteration then |
976 | order of execution is undefined. |
1119 | order of execution is undefined. |
|
|
1120 | |
|
|
1121 | =head3 Watcher-Specific Functions and Data Members |
977 | |
1122 | |
978 | =over 4 |
1123 | =over 4 |
979 | |
1124 | |
980 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1125 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
981 | |
1126 | |
… | |
… | |
1087 | |
1232 | |
1088 | As with timers, the callback is guarenteed to be invoked only when the |
1233 | As with timers, the callback is guarenteed to be invoked only when the |
1089 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1234 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1090 | during the same loop iteration then order of execution is undefined. |
1235 | during the same loop iteration then order of execution is undefined. |
1091 | |
1236 | |
|
|
1237 | =head3 Watcher-Specific Functions and Data Members |
|
|
1238 | |
1092 | =over 4 |
1239 | =over 4 |
1093 | |
1240 | |
1094 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1241 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1095 | |
1242 | |
1096 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1243 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1191 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1338 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1192 | |
1339 | |
1193 | The current reschedule callback, or C<0>, if this functionality is |
1340 | The current reschedule callback, or C<0>, if this functionality is |
1194 | switched off. Can be changed any time, but changes only take effect when |
1341 | switched off. Can be changed any time, but changes only take effect when |
1195 | the periodic timer fires or C<ev_periodic_again> is being called. |
1342 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1343 | |
|
|
1344 | =item ev_tstamp at [read-only] |
|
|
1345 | |
|
|
1346 | When active, contains the absolute time that the watcher is supposed to |
|
|
1347 | trigger next. |
1196 | |
1348 | |
1197 | =back |
1349 | =back |
1198 | |
1350 | |
1199 | Example: Call a callback every hour, or, more precisely, whenever the |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1200 | system clock is divisible by 3600. The callback invocation times have |
1352 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1242 | with the kernel (thus it coexists with your own signal handlers as long |
1394 | with the kernel (thus it coexists with your own signal handlers as long |
1243 | as you don't register any with libev). Similarly, when the last signal |
1395 | as you don't register any with libev). Similarly, when the last signal |
1244 | watcher for a signal is stopped libev will reset the signal handler to |
1396 | watcher for a signal is stopped libev will reset the signal handler to |
1245 | SIG_DFL (regardless of what it was set to before). |
1397 | SIG_DFL (regardless of what it was set to before). |
1246 | |
1398 | |
|
|
1399 | =head3 Watcher-Specific Functions and Data Members |
|
|
1400 | |
1247 | =over 4 |
1401 | =over 4 |
1248 | |
1402 | |
1249 | =item ev_signal_init (ev_signal *, callback, int signum) |
1403 | =item ev_signal_init (ev_signal *, callback, int signum) |
1250 | |
1404 | |
1251 | =item ev_signal_set (ev_signal *, int signum) |
1405 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1262 | |
1416 | |
1263 | =head2 C<ev_child> - watch out for process status changes |
1417 | =head2 C<ev_child> - watch out for process status changes |
1264 | |
1418 | |
1265 | Child watchers trigger when your process receives a SIGCHLD in response to |
1419 | Child watchers trigger when your process receives a SIGCHLD in response to |
1266 | some child status changes (most typically when a child of yours dies). |
1420 | some child status changes (most typically when a child of yours dies). |
|
|
1421 | |
|
|
1422 | =head3 Watcher-Specific Functions and Data Members |
1267 | |
1423 | |
1268 | =over 4 |
1424 | =over 4 |
1269 | |
1425 | |
1270 | =item ev_child_init (ev_child *, callback, int pid) |
1426 | =item ev_child_init (ev_child *, callback, int pid) |
1271 | |
1427 | |
… | |
… | |
1339 | reader). Inotify will be used to give hints only and should not change the |
1495 | reader). Inotify will be used to give hints only and should not change the |
1340 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1496 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1341 | to fall back to regular polling again even with inotify, but changes are |
1497 | to fall back to regular polling again even with inotify, but changes are |
1342 | usually detected immediately, and if the file exists there will be no |
1498 | usually detected immediately, and if the file exists there will be no |
1343 | polling. |
1499 | polling. |
|
|
1500 | |
|
|
1501 | =head3 Watcher-Specific Functions and Data Members |
1344 | |
1502 | |
1345 | =over 4 |
1503 | =over 4 |
1346 | |
1504 | |
1347 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1505 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1348 | |
1506 | |
… | |
… | |
1431 | Apart from keeping your process non-blocking (which is a useful |
1589 | Apart from keeping your process non-blocking (which is a useful |
1432 | effect on its own sometimes), idle watchers are a good place to do |
1590 | effect on its own sometimes), idle watchers are a good place to do |
1433 | "pseudo-background processing", or delay processing stuff to after the |
1591 | "pseudo-background processing", or delay processing stuff to after the |
1434 | event loop has handled all outstanding events. |
1592 | event loop has handled all outstanding events. |
1435 | |
1593 | |
|
|
1594 | =head3 Watcher-Specific Functions and Data Members |
|
|
1595 | |
1436 | =over 4 |
1596 | =over 4 |
1437 | |
1597 | |
1438 | =item ev_idle_init (ev_signal *, callback) |
1598 | =item ev_idle_init (ev_signal *, callback) |
1439 | |
1599 | |
1440 | Initialises and configures the idle watcher - it has no parameters of any |
1600 | Initialises and configures the idle watcher - it has no parameters of any |
… | |
… | |
1501 | |
1661 | |
1502 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1662 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1503 | priority, to ensure that they are being run before any other watchers |
1663 | priority, to ensure that they are being run before any other watchers |
1504 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1664 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1505 | too) should not activate ("feed") events into libev. While libev fully |
1665 | too) should not activate ("feed") events into libev. While libev fully |
1506 | supports this, they will be called before other C<ev_check> watchers did |
1666 | supports this, they will be called before other C<ev_check> watchers |
1507 | their job. As C<ev_check> watchers are often used to embed other event |
1667 | did their job. As C<ev_check> watchers are often used to embed other |
1508 | loops those other event loops might be in an unusable state until their |
1668 | (non-libev) event loops those other event loops might be in an unusable |
1509 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1669 | state until their C<ev_check> watcher ran (always remind yourself to |
1510 | others). |
1670 | coexist peacefully with others). |
|
|
1671 | |
|
|
1672 | =head3 Watcher-Specific Functions and Data Members |
1511 | |
1673 | |
1512 | =over 4 |
1674 | =over 4 |
1513 | |
1675 | |
1514 | =item ev_prepare_init (ev_prepare *, callback) |
1676 | =item ev_prepare_init (ev_prepare *, callback) |
1515 | |
1677 | |
… | |
… | |
1717 | ev_embed_start (loop_hi, &embed); |
1879 | ev_embed_start (loop_hi, &embed); |
1718 | } |
1880 | } |
1719 | else |
1881 | else |
1720 | loop_lo = loop_hi; |
1882 | loop_lo = loop_hi; |
1721 | |
1883 | |
|
|
1884 | =head3 Watcher-Specific Functions and Data Members |
|
|
1885 | |
1722 | =over 4 |
1886 | =over 4 |
1723 | |
1887 | |
1724 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1888 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1725 | |
1889 | |
1726 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1890 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1735 | |
1899 | |
1736 | Make a single, non-blocking sweep over the embedded loop. This works |
1900 | Make a single, non-blocking sweep over the embedded loop. This works |
1737 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1901 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1738 | apropriate way for embedded loops. |
1902 | apropriate way for embedded loops. |
1739 | |
1903 | |
1740 | =item struct ev_loop *loop [read-only] |
1904 | =item struct ev_loop *other [read-only] |
1741 | |
1905 | |
1742 | The embedded event loop. |
1906 | The embedded event loop. |
1743 | |
1907 | |
1744 | =back |
1908 | =back |
1745 | |
1909 | |
… | |
… | |
1752 | event loop blocks next and before C<ev_check> watchers are being called, |
1916 | event loop blocks next and before C<ev_check> watchers are being called, |
1753 | and only in the child after the fork. If whoever good citizen calling |
1917 | and only in the child after the fork. If whoever good citizen calling |
1754 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1918 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1755 | handlers will be invoked, too, of course. |
1919 | handlers will be invoked, too, of course. |
1756 | |
1920 | |
|
|
1921 | =head3 Watcher-Specific Functions and Data Members |
|
|
1922 | |
1757 | =over 4 |
1923 | =over 4 |
1758 | |
1924 | |
1759 | =item ev_fork_init (ev_signal *, callback) |
1925 | =item ev_fork_init (ev_signal *, callback) |
1760 | |
1926 | |
1761 | Initialises and configures the fork watcher - it has no parameters of any |
1927 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1977 | |
2143 | |
1978 | =item w->stop () |
2144 | =item w->stop () |
1979 | |
2145 | |
1980 | Stops the watcher if it is active. Again, no C<loop> argument. |
2146 | Stops the watcher if it is active. Again, no C<loop> argument. |
1981 | |
2147 | |
1982 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2148 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1983 | |
2149 | |
1984 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2150 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1985 | C<ev_TYPE_again> function. |
2151 | C<ev_TYPE_again> function. |
1986 | |
2152 | |
1987 | =item w->sweep () C<ev::embed> only |
2153 | =item w->sweep () (C<ev::embed> only) |
1988 | |
2154 | |
1989 | Invokes C<ev_embed_sweep>. |
2155 | Invokes C<ev_embed_sweep>. |
1990 | |
2156 | |
1991 | =item w->update () C<ev::stat> only |
2157 | =item w->update () (C<ev::stat> only) |
1992 | |
2158 | |
1993 | Invokes C<ev_stat_stat>. |
2159 | Invokes C<ev_stat_stat>. |
1994 | |
2160 | |
1995 | =back |
2161 | =back |
1996 | |
2162 | |
… | |
… | |
2016 | } |
2182 | } |
2017 | |
2183 | |
2018 | |
2184 | |
2019 | =head1 MACRO MAGIC |
2185 | =head1 MACRO MAGIC |
2020 | |
2186 | |
2021 | Libev can be compiled with a variety of options, the most fundemantal is |
2187 | Libev can be compiled with a variety of options, the most fundamantal |
2022 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2188 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2023 | callbacks have an initial C<struct ev_loop *> argument. |
2189 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2024 | |
2190 | |
2025 | To make it easier to write programs that cope with either variant, the |
2191 | To make it easier to write programs that cope with either variant, the |
2026 | following macros are defined: |
2192 | following macros are defined: |
2027 | |
2193 | |
2028 | =over 4 |
2194 | =over 4 |
… | |
… | |
2082 | Libev can (and often is) directly embedded into host |
2248 | Libev can (and often is) directly embedded into host |
2083 | applications. Examples of applications that embed it include the Deliantra |
2249 | applications. Examples of applications that embed it include the Deliantra |
2084 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2250 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2085 | and rxvt-unicode. |
2251 | and rxvt-unicode. |
2086 | |
2252 | |
2087 | The goal is to enable you to just copy the neecssary files into your |
2253 | The goal is to enable you to just copy the necessary files into your |
2088 | source directory without having to change even a single line in them, so |
2254 | source directory without having to change even a single line in them, so |
2089 | you can easily upgrade by simply copying (or having a checked-out copy of |
2255 | you can easily upgrade by simply copying (or having a checked-out copy of |
2090 | libev somewhere in your source tree). |
2256 | libev somewhere in your source tree). |
2091 | |
2257 | |
2092 | =head2 FILESETS |
2258 | =head2 FILESETS |
… | |
… | |
2182 | |
2348 | |
2183 | If defined to be C<1>, libev will try to detect the availability of the |
2349 | If defined to be C<1>, libev will try to detect the availability of the |
2184 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2350 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2185 | of the monotonic clock option will be attempted. If you enable this, you |
2351 | of the monotonic clock option will be attempted. If you enable this, you |
2186 | usually have to link against librt or something similar. Enabling it when |
2352 | usually have to link against librt or something similar. Enabling it when |
2187 | the functionality isn't available is safe, though, althoguh you have |
2353 | the functionality isn't available is safe, though, although you have |
2188 | to make sure you link against any libraries where the C<clock_gettime> |
2354 | to make sure you link against any libraries where the C<clock_gettime> |
2189 | function is hiding in (often F<-lrt>). |
2355 | function is hiding in (often F<-lrt>). |
2190 | |
2356 | |
2191 | =item EV_USE_REALTIME |
2357 | =item EV_USE_REALTIME |
2192 | |
2358 | |
2193 | If defined to be C<1>, libev will try to detect the availability of the |
2359 | If defined to be C<1>, libev will try to detect the availability of the |
2194 | realtime clock option at compiletime (and assume its availability at |
2360 | realtime clock option at compiletime (and assume its availability at |
2195 | runtime if successful). Otherwise no use of the realtime clock option will |
2361 | runtime if successful). Otherwise no use of the realtime clock option will |
2196 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2362 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2197 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2363 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2198 | in the description of C<EV_USE_MONOTONIC>, though. |
2364 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2365 | |
|
|
2366 | =item EV_USE_NANOSLEEP |
|
|
2367 | |
|
|
2368 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2369 | and will use it for delays. Otherwise it will use C<select ()>. |
2199 | |
2370 | |
2200 | =item EV_USE_SELECT |
2371 | =item EV_USE_SELECT |
2201 | |
2372 | |
2202 | If undefined or defined to be C<1>, libev will compile in support for the |
2373 | If undefined or defined to be C<1>, libev will compile in support for the |
2203 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2374 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2355 | than enough. If you need to manage thousands of children you might want to |
2526 | than enough. If you need to manage thousands of children you might want to |
2356 | increase this value (I<must> be a power of two). |
2527 | increase this value (I<must> be a power of two). |
2357 | |
2528 | |
2358 | =item EV_INOTIFY_HASHSIZE |
2529 | =item EV_INOTIFY_HASHSIZE |
2359 | |
2530 | |
2360 | C<ev_staz> watchers use a small hash table to distribute workload by |
2531 | C<ev_stat> watchers use a small hash table to distribute workload by |
2361 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2532 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2362 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2533 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2363 | watchers you might want to increase this value (I<must> be a power of |
2534 | watchers you might want to increase this value (I<must> be a power of |
2364 | two). |
2535 | two). |
2365 | |
2536 | |
… | |
… | |
2382 | |
2553 | |
2383 | =item ev_set_cb (ev, cb) |
2554 | =item ev_set_cb (ev, cb) |
2384 | |
2555 | |
2385 | Can be used to change the callback member declaration in each watcher, |
2556 | Can be used to change the callback member declaration in each watcher, |
2386 | and the way callbacks are invoked and set. Must expand to a struct member |
2557 | and the way callbacks are invoked and set. Must expand to a struct member |
2387 | definition and a statement, respectively. See the F<ev.v> header file for |
2558 | definition and a statement, respectively. See the F<ev.h> header file for |
2388 | their default definitions. One possible use for overriding these is to |
2559 | their default definitions. One possible use for overriding these is to |
2389 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2560 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2390 | method calls instead of plain function calls in C++. |
2561 | method calls instead of plain function calls in C++. |
|
|
2562 | |
|
|
2563 | =head2 EXPORTED API SYMBOLS |
|
|
2564 | |
|
|
2565 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2566 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2567 | all public symbols, one per line: |
|
|
2568 | |
|
|
2569 | Symbols.ev for libev proper |
|
|
2570 | Symbols.event for the libevent emulation |
|
|
2571 | |
|
|
2572 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2573 | multiple versions of libev linked together (which is obviously bad in |
|
|
2574 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2575 | |
|
|
2576 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2577 | include before including F<ev.h>: |
|
|
2578 | |
|
|
2579 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2580 | |
|
|
2581 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2582 | |
|
|
2583 | #define ev_backend myprefix_ev_backend |
|
|
2584 | #define ev_check_start myprefix_ev_check_start |
|
|
2585 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2586 | ... |
2391 | |
2587 | |
2392 | =head2 EXAMPLES |
2588 | =head2 EXAMPLES |
2393 | |
2589 | |
2394 | For a real-world example of a program the includes libev |
2590 | For a real-world example of a program the includes libev |
2395 | verbatim, you can have a look at the EV perl module |
2591 | verbatim, you can have a look at the EV perl module |