… | |
… | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
|
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53 | The newest version of this document is also available as a html-formatted |
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54 | web page you might find easier to navigate when reading it for the first |
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
|
|
56 | |
53 | 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 |
54 | 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 |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
57 | 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 |
58 | (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 |
59 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
94 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | 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 |
97 | 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 |
98 | 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 |
99 | 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. |
100 | |
106 | |
101 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
102 | |
108 | |
103 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
104 | library in any way. |
110 | library in any way. |
… | |
… | |
109 | |
115 | |
110 | 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 |
111 | 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 |
112 | you actually want to know. |
118 | you actually want to know. |
113 | |
119 | |
|
|
120 | =item ev_sleep (ev_tstamp interval) |
|
|
121 | |
|
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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 | |
114 | =item int ev_version_major () |
126 | =item int ev_version_major () |
115 | |
127 | |
116 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
117 | |
129 | |
118 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
119 | 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 |
120 | 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 |
121 | 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 |
122 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
123 | |
135 | |
|
|
136 | These version numbers refer to the ABI version of the library, not the |
|
|
137 | release version. |
|
|
138 | |
124 | 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, |
125 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
126 | 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 |
127 | not a problem. |
142 | not a problem. |
128 | |
143 | |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
144 | Example: Make sure we haven't accidentally been linked against the wrong |
130 | version. |
145 | version. |
… | |
… | |
304 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
319 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
305 | |
320 | |
306 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
321 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
307 | |
322 | |
308 | For few fds, this backend is a bit little slower than poll and select, |
323 | For few fds, this backend is a bit little slower than poll and select, |
309 | but it scales phenomenally better. While poll and select usually scale like |
324 | but it scales phenomenally better. While poll and select usually scale |
310 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
325 | like O(total_fds) where n is the total number of fds (or the highest fd), |
311 | either O(1) or O(active_fds). |
326 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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|
327 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
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328 | cases and rewiring a syscall per fd change, no fork support and bad |
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329 | support for dup: |
312 | |
330 | |
313 | While stopping and starting an I/O watcher in the same iteration will |
331 | While stopping, setting and starting an I/O watcher in the same iteration |
314 | result in some caching, there is still a syscall per such incident |
332 | will result in some caching, there is still a syscall per such incident |
315 | (because the fd could point to a different file description now), so its |
333 | (because the fd could point to a different file description now), so its |
316 | best to avoid that. Also, dup()ed file descriptors might not work very |
334 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
317 | well if you register events for both fds. |
335 | very well if you register events for both fds. |
318 | |
336 | |
319 | Please note that epoll sometimes generates spurious notifications, so you |
337 | Please note that epoll sometimes generates spurious notifications, so you |
320 | need to use non-blocking I/O or other means to avoid blocking when no data |
338 | need to use non-blocking I/O or other means to avoid blocking when no data |
321 | (or space) is available. |
339 | (or space) is available. |
322 | |
340 | |
323 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
341 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
324 | |
342 | |
325 | Kqueue deserves special mention, as at the time of this writing, it |
343 | Kqueue deserves special mention, as at the time of this writing, it |
326 | was broken on all BSDs except NetBSD (usually it doesn't work with |
344 | was broken on I<all> BSDs (usually it doesn't work with anything but |
327 | anything but sockets and pipes, except on Darwin, where of course its |
345 | sockets and pipes, except on Darwin, where of course it's completely |
|
|
346 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
328 | completely useless). For this reason its not being "autodetected" |
347 | is used by default there). For this reason it's not being "autodetected" |
329 | unless you explicitly specify it explicitly in the flags (i.e. using |
348 | unless you explicitly specify it explicitly in the flags (i.e. using |
330 | C<EVBACKEND_KQUEUE>). |
349 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
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|
350 | system like NetBSD. |
331 | |
351 | |
332 | It scales in the same way as the epoll backend, but the interface to the |
352 | It scales in the same way as the epoll backend, but the interface to the |
333 | kernel is more efficient (which says nothing about its actual speed, of |
353 | kernel is more efficient (which says nothing about its actual speed, |
334 | course). While starting and stopping an I/O watcher does not cause an |
354 | of course). While stopping, setting and starting an I/O watcher does |
335 | extra syscall as with epoll, it still adds up to four event changes per |
355 | never cause an extra syscall as with epoll, it still adds up to two event |
336 | incident, so its best to avoid that. |
356 | changes per incident, support for C<fork ()> is very bad and it drops fds |
|
|
357 | silently in similarly hard-to-detetc cases. |
337 | |
358 | |
338 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
359 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
339 | |
360 | |
340 | This is not implemented yet (and might never be). |
361 | This is not implemented yet (and might never be). |
341 | |
362 | |
342 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
363 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
343 | |
364 | |
344 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
365 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
345 | it's really slow, but it still scales very well (O(active_fds)). |
366 | it's really slow, but it still scales very well (O(active_fds)). |
346 | |
367 | |
347 | Please note that solaris ports can result in a lot of spurious |
368 | Please note that solaris event ports can deliver a lot of spurious |
348 | notifications, so you need to use non-blocking I/O or other means to avoid |
369 | notifications, so you need to use non-blocking I/O or other means to avoid |
349 | blocking when no data (or space) is available. |
370 | blocking when no data (or space) is available. |
350 | |
371 | |
351 | =item C<EVBACKEND_ALL> |
372 | =item C<EVBACKEND_ALL> |
352 | |
373 | |
… | |
… | |
395 | Destroys the default loop again (frees all memory and kernel state |
416 | Destroys the default loop again (frees all memory and kernel state |
396 | etc.). None of the active event watchers will be stopped in the normal |
417 | etc.). None of the active event watchers will be stopped in the normal |
397 | sense, so e.g. C<ev_is_active> might still return true. It is your |
418 | sense, so e.g. C<ev_is_active> might still return true. It is your |
398 | responsibility to either stop all watchers cleanly yoursef I<before> |
419 | responsibility to either stop all watchers cleanly yoursef I<before> |
399 | calling this function, or cope with the fact afterwards (which is usually |
420 | calling this function, or cope with the fact afterwards (which is usually |
400 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
421 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
401 | for example). |
422 | for example). |
|
|
423 | |
|
|
424 | Note that certain global state, such as signal state, will not be freed by |
|
|
425 | this function, and related watchers (such as signal and child watchers) |
|
|
426 | would need to be stopped manually. |
|
|
427 | |
|
|
428 | In general it is not advisable to call this function except in the |
|
|
429 | rare occasion where you really need to free e.g. the signal handling |
|
|
430 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
431 | C<ev_loop_new> and C<ev_loop_destroy>). |
402 | |
432 | |
403 | =item ev_loop_destroy (loop) |
433 | =item ev_loop_destroy (loop) |
404 | |
434 | |
405 | Like C<ev_default_destroy>, but destroys an event loop created by an |
435 | Like C<ev_default_destroy>, but destroys an event loop created by an |
406 | earlier call to C<ev_loop_new>. |
436 | earlier call to C<ev_loop_new>. |
… | |
… | |
451 | |
481 | |
452 | Returns the current "event loop time", which is the time the event loop |
482 | Returns the current "event loop time", which is the time the event loop |
453 | received events and started processing them. This timestamp does not |
483 | received events and started processing them. This timestamp does not |
454 | change as long as callbacks are being processed, and this is also the base |
484 | change as long as callbacks are being processed, and this is also the base |
455 | time used for relative timers. You can treat it as the timestamp of the |
485 | time used for relative timers. You can treat it as the timestamp of the |
456 | event occuring (or more correctly, libev finding out about it). |
486 | event occurring (or more correctly, libev finding out about it). |
457 | |
487 | |
458 | =item ev_loop (loop, int flags) |
488 | =item ev_loop (loop, int flags) |
459 | |
489 | |
460 | Finally, this is it, the event handler. This function usually is called |
490 | Finally, this is it, the event handler. This function usually is called |
461 | after you initialised all your watchers and you want to start handling |
491 | after you initialised all your watchers and you want to start handling |
… | |
… | |
482 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
512 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
483 | usually a better approach for this kind of thing. |
513 | usually a better approach for this kind of thing. |
484 | |
514 | |
485 | Here are the gory details of what C<ev_loop> does: |
515 | Here are the gory details of what C<ev_loop> does: |
486 | |
516 | |
|
|
517 | - Before the first iteration, call any pending watchers. |
487 | * If there are no active watchers (reference count is zero), return. |
518 | * If there are no active watchers (reference count is zero), return. |
488 | - Queue prepare watchers and then call all outstanding watchers. |
519 | - Queue all prepare watchers and then call all outstanding watchers. |
489 | - If we have been forked, recreate the kernel state. |
520 | - If we have been forked, recreate the kernel state. |
490 | - Update the kernel state with all outstanding changes. |
521 | - Update the kernel state with all outstanding changes. |
491 | - Update the "event loop time". |
522 | - Update the "event loop time". |
492 | - Calculate for how long to block. |
523 | - Calculate for how long to block. |
493 | - Block the process, waiting for any events. |
524 | - Block the process, waiting for any events. |
… | |
… | |
544 | Example: For some weird reason, unregister the above signal handler again. |
575 | Example: For some weird reason, unregister the above signal handler again. |
545 | |
576 | |
546 | ev_ref (loop); |
577 | ev_ref (loop); |
547 | ev_signal_stop (loop, &exitsig); |
578 | ev_signal_stop (loop, &exitsig); |
548 | |
579 | |
|
|
580 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
581 | |
|
|
582 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
583 | |
|
|
584 | These advanced functions influence the time that libev will spend waiting |
|
|
585 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
586 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
587 | |
|
|
588 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
589 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
590 | increase efficiency of loop iterations. |
|
|
591 | |
|
|
592 | The background is that sometimes your program runs just fast enough to |
|
|
593 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
594 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
595 | events, especially with backends like C<select ()> which have a high |
|
|
596 | overhead for the actual polling but can deliver many events at once. |
|
|
597 | |
|
|
598 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
599 | time collecting I/O events, so you can handle more events per iteration, |
|
|
600 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
601 | C<ev_timer>) will be not affected. Setting this to a non-null bvalue will |
|
|
602 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
603 | |
|
|
604 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
605 | to spend more time collecting timeouts, at the expense of increased |
|
|
606 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
607 | will not be affected. Setting this to a non-null value will not introduce |
|
|
608 | any overhead in libev. |
|
|
609 | |
|
|
610 | Many (busy) programs can usually benefit by setting the io collect |
|
|
611 | interval to a value near C<0.1> or so, which is often enough for |
|
|
612 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
613 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
614 | as this approsaches the timing granularity of most systems. |
|
|
615 | |
549 | =back |
616 | =back |
550 | |
617 | |
551 | |
618 | |
552 | =head1 ANATOMY OF A WATCHER |
619 | =head1 ANATOMY OF A WATCHER |
553 | |
620 | |
… | |
… | |
732 | =item bool ev_is_pending (ev_TYPE *watcher) |
799 | =item bool ev_is_pending (ev_TYPE *watcher) |
733 | |
800 | |
734 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
801 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
735 | events but its callback has not yet been invoked). As long as a watcher |
802 | events but its callback has not yet been invoked). As long as a watcher |
736 | is pending (but not active) you must not call an init function on it (but |
803 | is pending (but not active) you must not call an init function on it (but |
737 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
804 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
738 | libev (e.g. you cnanot C<free ()> it). |
805 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
806 | it). |
739 | |
807 | |
740 | =item callback ev_cb (ev_TYPE *watcher) |
808 | =item callback ev_cb (ev_TYPE *watcher) |
741 | |
809 | |
742 | Returns the callback currently set on the watcher. |
810 | Returns the callback currently set on the watcher. |
743 | |
811 | |
… | |
… | |
762 | watchers on the same event and make sure one is called first. |
830 | watchers on the same event and make sure one is called first. |
763 | |
831 | |
764 | If you need to suppress invocation when higher priority events are pending |
832 | If you need to suppress invocation when higher priority events are pending |
765 | you need to look at C<ev_idle> watchers, which provide this functionality. |
833 | you need to look at C<ev_idle> watchers, which provide this functionality. |
766 | |
834 | |
|
|
835 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
836 | pending. |
|
|
837 | |
767 | The default priority used by watchers when no priority has been set is |
838 | The default priority used by watchers when no priority has been set is |
768 | always C<0>, which is supposed to not be too high and not be too low :). |
839 | always C<0>, which is supposed to not be too high and not be too low :). |
769 | |
840 | |
770 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
841 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
771 | fine, as long as you do not mind that the priority value you query might |
842 | fine, as long as you do not mind that the priority value you query might |
772 | or might not have been adjusted to be within valid range. |
843 | or might not have been adjusted to be within valid range. |
|
|
844 | |
|
|
845 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
846 | |
|
|
847 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
848 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
849 | can deal with that fact. |
|
|
850 | |
|
|
851 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
852 | |
|
|
853 | If the watcher is pending, this function returns clears its pending status |
|
|
854 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
855 | watcher isn't pending it does nothing and returns C<0>. |
773 | |
856 | |
774 | =back |
857 | =back |
775 | |
858 | |
776 | |
859 | |
777 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
860 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
887 | play around with an Xlib connection), then you have to seperately re-test |
970 | play around with an Xlib connection), then you have to seperately re-test |
888 | whether a file descriptor is really ready with a known-to-be good interface |
971 | whether a file descriptor is really ready with a known-to-be good interface |
889 | such as poll (fortunately in our Xlib example, Xlib already does this on |
972 | such as poll (fortunately in our Xlib example, Xlib already does this on |
890 | its own, so its quite safe to use). |
973 | its own, so its quite safe to use). |
891 | |
974 | |
|
|
975 | =head3 The special problem of disappearing file descriptors |
|
|
976 | |
|
|
977 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
978 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
979 | such as C<dup>). The reason is that you register interest in some file |
|
|
980 | descriptor, but when it goes away, the operating system will silently drop |
|
|
981 | this interest. If another file descriptor with the same number then is |
|
|
982 | registered with libev, there is no efficient way to see that this is, in |
|
|
983 | fact, a different file descriptor. |
|
|
984 | |
|
|
985 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
986 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
987 | will assume that this is potentially a new file descriptor, otherwise |
|
|
988 | it is assumed that the file descriptor stays the same. That means that |
|
|
989 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
990 | descriptor even if the file descriptor number itself did not change. |
|
|
991 | |
|
|
992 | This is how one would do it normally anyway, the important point is that |
|
|
993 | the libev application should not optimise around libev but should leave |
|
|
994 | optimisations to libev. |
|
|
995 | |
|
|
996 | =head3 The special problem of dup'ed file descriptors |
|
|
997 | |
|
|
998 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
999 | but only events for the underlying file descriptions. That menas when you |
|
|
1000 | have C<dup ()>'ed file descriptors and register events for them, only one |
|
|
1001 | file descriptor might actually receive events. |
|
|
1002 | |
|
|
1003 | There is no workaorund possible except not registering events |
|
|
1004 | for potentially C<dup ()>'ed file descriptors or to resort to |
|
|
1005 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1006 | |
|
|
1007 | =head3 The special problem of fork |
|
|
1008 | |
|
|
1009 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1010 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1011 | it in the child. |
|
|
1012 | |
|
|
1013 | To support fork in your programs, you either have to call |
|
|
1014 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1015 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1016 | C<EVBACKEND_POLL>. |
|
|
1017 | |
|
|
1018 | |
|
|
1019 | =head3 Watcher-Specific Functions |
|
|
1020 | |
892 | =over 4 |
1021 | =over 4 |
893 | |
1022 | |
894 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1023 | =item ev_io_init (ev_io *, callback, int fd, int events) |
895 | |
1024 | |
896 | =item ev_io_set (ev_io *, int fd, int events) |
1025 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
948 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1077 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
949 | |
1078 | |
950 | The callback is guarenteed to be invoked only when its timeout has passed, |
1079 | The callback is guarenteed to be invoked only when its timeout has passed, |
951 | but if multiple timers become ready during the same loop iteration then |
1080 | but if multiple timers become ready during the same loop iteration then |
952 | order of execution is undefined. |
1081 | order of execution is undefined. |
|
|
1082 | |
|
|
1083 | =head3 Watcher-Specific Functions and Data Members |
953 | |
1084 | |
954 | =over 4 |
1085 | =over 4 |
955 | |
1086 | |
956 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1087 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
957 | |
1088 | |
… | |
… | |
1053 | but on wallclock time (absolute time). You can tell a periodic watcher |
1184 | but on wallclock time (absolute time). You can tell a periodic watcher |
1054 | to trigger "at" some specific point in time. For example, if you tell a |
1185 | to trigger "at" some specific point in time. For example, if you tell a |
1055 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1186 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1056 | + 10.>) and then reset your system clock to the last year, then it will |
1187 | + 10.>) and then reset your system clock to the last year, then it will |
1057 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1188 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1058 | roughly 10 seconds later and of course not if you reset your system time |
1189 | roughly 10 seconds later). |
1059 | again). |
|
|
1060 | |
1190 | |
1061 | They can also be used to implement vastly more complex timers, such as |
1191 | They can also be used to implement vastly more complex timers, such as |
1062 | triggering an event on eahc midnight, local time. |
1192 | triggering an event on each midnight, local time or other, complicated, |
|
|
1193 | rules. |
1063 | |
1194 | |
1064 | As with timers, the callback is guarenteed to be invoked only when the |
1195 | As with timers, the callback is guarenteed to be invoked only when the |
1065 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1196 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1066 | during the same loop iteration then order of execution is undefined. |
1197 | during the same loop iteration then order of execution is undefined. |
1067 | |
1198 | |
|
|
1199 | =head3 Watcher-Specific Functions and Data Members |
|
|
1200 | |
1068 | =over 4 |
1201 | =over 4 |
1069 | |
1202 | |
1070 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1203 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1071 | |
1204 | |
1072 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1205 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1074 | Lots of arguments, lets sort it out... There are basically three modes of |
1207 | Lots of arguments, lets sort it out... There are basically three modes of |
1075 | operation, and we will explain them from simplest to complex: |
1208 | operation, and we will explain them from simplest to complex: |
1076 | |
1209 | |
1077 | =over 4 |
1210 | =over 4 |
1078 | |
1211 | |
1079 | =item * absolute timer (interval = reschedule_cb = 0) |
1212 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1080 | |
1213 | |
1081 | In this configuration the watcher triggers an event at the wallclock time |
1214 | In this configuration the watcher triggers an event at the wallclock time |
1082 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1215 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1083 | that is, if it is to be run at January 1st 2011 then it will run when the |
1216 | that is, if it is to be run at January 1st 2011 then it will run when the |
1084 | system time reaches or surpasses this time. |
1217 | system time reaches or surpasses this time. |
1085 | |
1218 | |
1086 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1219 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1087 | |
1220 | |
1088 | In this mode the watcher will always be scheduled to time out at the next |
1221 | In this mode the watcher will always be scheduled to time out at the next |
1089 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1222 | C<at + N * interval> time (for some integer N, which can also be negative) |
1090 | of any time jumps. |
1223 | and then repeat, regardless of any time jumps. |
1091 | |
1224 | |
1092 | This can be used to create timers that do not drift with respect to system |
1225 | This can be used to create timers that do not drift with respect to system |
1093 | time: |
1226 | time: |
1094 | |
1227 | |
1095 | ev_periodic_set (&periodic, 0., 3600., 0); |
1228 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1101 | |
1234 | |
1102 | Another way to think about it (for the mathematically inclined) is that |
1235 | Another way to think about it (for the mathematically inclined) is that |
1103 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1236 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1104 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1237 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1105 | |
1238 | |
|
|
1239 | For numerical stability it is preferable that the C<at> value is near |
|
|
1240 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1241 | this value. |
|
|
1242 | |
1106 | =item * manual reschedule mode (reschedule_cb = callback) |
1243 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1107 | |
1244 | |
1108 | In this mode the values for C<interval> and C<at> are both being |
1245 | In this mode the values for C<interval> and C<at> are both being |
1109 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1246 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1110 | reschedule callback will be called with the watcher as first, and the |
1247 | reschedule callback will be called with the watcher as first, and the |
1111 | current time as second argument. |
1248 | current time as second argument. |
1112 | |
1249 | |
1113 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1250 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1114 | ever, or make any event loop modifications>. If you need to stop it, |
1251 | ever, or make any event loop modifications>. If you need to stop it, |
1115 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1252 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1116 | starting a prepare watcher). |
1253 | starting an C<ev_prepare> watcher, which is legal). |
1117 | |
1254 | |
1118 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1255 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1119 | ev_tstamp now)>, e.g.: |
1256 | ev_tstamp now)>, e.g.: |
1120 | |
1257 | |
1121 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1258 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1144 | Simply stops and restarts the periodic watcher again. This is only useful |
1281 | Simply stops and restarts the periodic watcher again. This is only useful |
1145 | when you changed some parameters or the reschedule callback would return |
1282 | when you changed some parameters or the reschedule callback would return |
1146 | a different time than the last time it was called (e.g. in a crond like |
1283 | a different time than the last time it was called (e.g. in a crond like |
1147 | program when the crontabs have changed). |
1284 | program when the crontabs have changed). |
1148 | |
1285 | |
|
|
1286 | =item ev_tstamp offset [read-write] |
|
|
1287 | |
|
|
1288 | When repeating, this contains the offset value, otherwise this is the |
|
|
1289 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1290 | |
|
|
1291 | Can be modified any time, but changes only take effect when the periodic |
|
|
1292 | timer fires or C<ev_periodic_again> is being called. |
|
|
1293 | |
1149 | =item ev_tstamp interval [read-write] |
1294 | =item ev_tstamp interval [read-write] |
1150 | |
1295 | |
1151 | The current interval value. Can be modified any time, but changes only |
1296 | The current interval value. Can be modified any time, but changes only |
1152 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1297 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1153 | called. |
1298 | called. |
… | |
… | |
1155 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1300 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1156 | |
1301 | |
1157 | The current reschedule callback, or C<0>, if this functionality is |
1302 | The current reschedule callback, or C<0>, if this functionality is |
1158 | switched off. Can be changed any time, but changes only take effect when |
1303 | switched off. Can be changed any time, but changes only take effect when |
1159 | the periodic timer fires or C<ev_periodic_again> is being called. |
1304 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1305 | |
|
|
1306 | =item ev_tstamp at [read-only] |
|
|
1307 | |
|
|
1308 | When active, contains the absolute time that the watcher is supposed to |
|
|
1309 | trigger next. |
1160 | |
1310 | |
1161 | =back |
1311 | =back |
1162 | |
1312 | |
1163 | Example: Call a callback every hour, or, more precisely, whenever the |
1313 | Example: Call a callback every hour, or, more precisely, whenever the |
1164 | system clock is divisible by 3600. The callback invocation times have |
1314 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1206 | with the kernel (thus it coexists with your own signal handlers as long |
1356 | with the kernel (thus it coexists with your own signal handlers as long |
1207 | as you don't register any with libev). Similarly, when the last signal |
1357 | as you don't register any with libev). Similarly, when the last signal |
1208 | watcher for a signal is stopped libev will reset the signal handler to |
1358 | watcher for a signal is stopped libev will reset the signal handler to |
1209 | SIG_DFL (regardless of what it was set to before). |
1359 | SIG_DFL (regardless of what it was set to before). |
1210 | |
1360 | |
|
|
1361 | =head3 Watcher-Specific Functions and Data Members |
|
|
1362 | |
1211 | =over 4 |
1363 | =over 4 |
1212 | |
1364 | |
1213 | =item ev_signal_init (ev_signal *, callback, int signum) |
1365 | =item ev_signal_init (ev_signal *, callback, int signum) |
1214 | |
1366 | |
1215 | =item ev_signal_set (ev_signal *, int signum) |
1367 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1226 | |
1378 | |
1227 | =head2 C<ev_child> - watch out for process status changes |
1379 | =head2 C<ev_child> - watch out for process status changes |
1228 | |
1380 | |
1229 | Child watchers trigger when your process receives a SIGCHLD in response to |
1381 | Child watchers trigger when your process receives a SIGCHLD in response to |
1230 | some child status changes (most typically when a child of yours dies). |
1382 | some child status changes (most typically when a child of yours dies). |
|
|
1383 | |
|
|
1384 | =head3 Watcher-Specific Functions and Data Members |
1231 | |
1385 | |
1232 | =over 4 |
1386 | =over 4 |
1233 | |
1387 | |
1234 | =item ev_child_init (ev_child *, callback, int pid) |
1388 | =item ev_child_init (ev_child *, callback, int pid) |
1235 | |
1389 | |
… | |
… | |
1303 | reader). Inotify will be used to give hints only and should not change the |
1457 | reader). Inotify will be used to give hints only and should not change the |
1304 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1458 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1305 | to fall back to regular polling again even with inotify, but changes are |
1459 | to fall back to regular polling again even with inotify, but changes are |
1306 | usually detected immediately, and if the file exists there will be no |
1460 | usually detected immediately, and if the file exists there will be no |
1307 | polling. |
1461 | polling. |
|
|
1462 | |
|
|
1463 | =head3 Watcher-Specific Functions and Data Members |
1308 | |
1464 | |
1309 | =over 4 |
1465 | =over 4 |
1310 | |
1466 | |
1311 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1467 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1312 | |
1468 | |
… | |
… | |
1395 | Apart from keeping your process non-blocking (which is a useful |
1551 | Apart from keeping your process non-blocking (which is a useful |
1396 | effect on its own sometimes), idle watchers are a good place to do |
1552 | effect on its own sometimes), idle watchers are a good place to do |
1397 | "pseudo-background processing", or delay processing stuff to after the |
1553 | "pseudo-background processing", or delay processing stuff to after the |
1398 | event loop has handled all outstanding events. |
1554 | event loop has handled all outstanding events. |
1399 | |
1555 | |
|
|
1556 | =head3 Watcher-Specific Functions and Data Members |
|
|
1557 | |
1400 | =over 4 |
1558 | =over 4 |
1401 | |
1559 | |
1402 | =item ev_idle_init (ev_signal *, callback) |
1560 | =item ev_idle_init (ev_signal *, callback) |
1403 | |
1561 | |
1404 | Initialises and configures the idle watcher - it has no parameters of any |
1562 | Initialises and configures the idle watcher - it has no parameters of any |
… | |
… | |
1461 | with priority higher than or equal to the event loop and one coroutine |
1619 | with priority higher than or equal to the event loop and one coroutine |
1462 | of lower priority, but only once, using idle watchers to keep the event |
1620 | of lower priority, but only once, using idle watchers to keep the event |
1463 | loop from blocking if lower-priority coroutines are active, thus mapping |
1621 | loop from blocking if lower-priority coroutines are active, thus mapping |
1464 | low-priority coroutines to idle/background tasks). |
1622 | low-priority coroutines to idle/background tasks). |
1465 | |
1623 | |
|
|
1624 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1625 | priority, to ensure that they are being run before any other watchers |
|
|
1626 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1627 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1628 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1629 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1630 | loops those other event loops might be in an unusable state until their |
|
|
1631 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1632 | others). |
|
|
1633 | |
|
|
1634 | =head3 Watcher-Specific Functions and Data Members |
|
|
1635 | |
1466 | =over 4 |
1636 | =over 4 |
1467 | |
1637 | |
1468 | =item ev_prepare_init (ev_prepare *, callback) |
1638 | =item ev_prepare_init (ev_prepare *, callback) |
1469 | |
1639 | |
1470 | =item ev_check_init (ev_check *, callback) |
1640 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1473 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1643 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1474 | macros, but using them is utterly, utterly and completely pointless. |
1644 | macros, but using them is utterly, utterly and completely pointless. |
1475 | |
1645 | |
1476 | =back |
1646 | =back |
1477 | |
1647 | |
1478 | Example: To include a library such as adns, you would add IO watchers |
1648 | There are a number of principal ways to embed other event loops or modules |
1479 | and a timeout watcher in a prepare handler, as required by libadns, and |
1649 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1650 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1651 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1652 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1653 | into the Glib event loop). |
|
|
1654 | |
|
|
1655 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1480 | in a check watcher, destroy them and call into libadns. What follows is |
1656 | and in a check watcher, destroy them and call into libadns. What follows |
1481 | pseudo-code only of course: |
1657 | is pseudo-code only of course. This requires you to either use a low |
|
|
1658 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1659 | the callbacks for the IO/timeout watchers might not have been called yet. |
1482 | |
1660 | |
1483 | static ev_io iow [nfd]; |
1661 | static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1662 | static ev_timer tw; |
1485 | |
1663 | |
1486 | static void |
1664 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1665 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1666 | { |
1489 | // set the relevant poll flags |
|
|
1490 | // could also call adns_processreadable etc. here |
|
|
1491 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1492 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1493 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1494 | } |
1667 | } |
1495 | |
1668 | |
1496 | // create io watchers for each fd and a timer before blocking |
1669 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1670 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1671 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1677 | |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1678 | /* the callback is illegal, but won't be called as we stop during check */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1679 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1680 | ev_timer_start (loop, &tw); |
1508 | |
1681 | |
1509 | // create on ev_io per pollfd |
1682 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1683 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1684 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1685 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1686 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1687 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1688 | |
1516 | fds [i].revents = 0; |
1689 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1690 | ev_io_start (loop, iow + i); |
1519 | } |
1691 | } |
1520 | } |
1692 | } |
1521 | |
1693 | |
1522 | // stop all watchers after blocking |
1694 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1696 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1697 | { |
1526 | ev_timer_stop (loop, &tw); |
1698 | ev_timer_stop (loop, &tw); |
1527 | |
1699 | |
1528 | for (int i = 0; i < nfd; ++i) |
1700 | for (int i = 0; i < nfd; ++i) |
|
|
1701 | { |
|
|
1702 | // set the relevant poll flags |
|
|
1703 | // could also call adns_processreadable etc. here |
|
|
1704 | struct pollfd *fd = fds + i; |
|
|
1705 | int revents = ev_clear_pending (iow + i); |
|
|
1706 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1707 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1708 | |
|
|
1709 | // now stop the watcher |
1529 | ev_io_stop (loop, iow + i); |
1710 | ev_io_stop (loop, iow + i); |
|
|
1711 | } |
1530 | |
1712 | |
1531 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1713 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1714 | } |
|
|
1715 | |
|
|
1716 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1717 | in the prepare watcher and would dispose of the check watcher. |
|
|
1718 | |
|
|
1719 | Method 3: If the module to be embedded supports explicit event |
|
|
1720 | notification (adns does), you can also make use of the actual watcher |
|
|
1721 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1722 | |
|
|
1723 | static void |
|
|
1724 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1725 | { |
|
|
1726 | adns_state ads = (adns_state)w->data; |
|
|
1727 | update_now (EV_A); |
|
|
1728 | |
|
|
1729 | adns_processtimeouts (ads, &tv_now); |
|
|
1730 | } |
|
|
1731 | |
|
|
1732 | static void |
|
|
1733 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1734 | { |
|
|
1735 | adns_state ads = (adns_state)w->data; |
|
|
1736 | update_now (EV_A); |
|
|
1737 | |
|
|
1738 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1739 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1740 | } |
|
|
1741 | |
|
|
1742 | // do not ever call adns_afterpoll |
|
|
1743 | |
|
|
1744 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1745 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1746 | their poll function. The drawback with this solution is that the main |
|
|
1747 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1748 | this. |
|
|
1749 | |
|
|
1750 | static gint |
|
|
1751 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1752 | { |
|
|
1753 | int got_events = 0; |
|
|
1754 | |
|
|
1755 | for (n = 0; n < nfds; ++n) |
|
|
1756 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1757 | |
|
|
1758 | if (timeout >= 0) |
|
|
1759 | // create/start timer |
|
|
1760 | |
|
|
1761 | // poll |
|
|
1762 | ev_loop (EV_A_ 0); |
|
|
1763 | |
|
|
1764 | // stop timer again |
|
|
1765 | if (timeout >= 0) |
|
|
1766 | ev_timer_stop (EV_A_ &to); |
|
|
1767 | |
|
|
1768 | // stop io watchers again - their callbacks should have set |
|
|
1769 | for (n = 0; n < nfds; ++n) |
|
|
1770 | ev_io_stop (EV_A_ iow [n]); |
|
|
1771 | |
|
|
1772 | return got_events; |
1532 | } |
1773 | } |
1533 | |
1774 | |
1534 | |
1775 | |
1535 | =head2 C<ev_embed> - when one backend isn't enough... |
1776 | =head2 C<ev_embed> - when one backend isn't enough... |
1536 | |
1777 | |
1537 | This is a rather advanced watcher type that lets you embed one event loop |
1778 | This is a rather advanced watcher type that lets you embed one event loop |
1538 | into another (currently only C<ev_io> events are supported in the embedded |
1779 | into another (currently only C<ev_io> events are supported in the embedded |
1539 | loop, other types of watchers might be handled in a delayed or incorrect |
1780 | loop, other types of watchers might be handled in a delayed or incorrect |
1540 | fashion and must not be used). |
1781 | fashion and must not be used). (See portability notes, below). |
1541 | |
1782 | |
1542 | There are primarily two reasons you would want that: work around bugs and |
1783 | There are primarily two reasons you would want that: work around bugs and |
1543 | prioritise I/O. |
1784 | prioritise I/O. |
1544 | |
1785 | |
1545 | As an example for a bug workaround, the kqueue backend might only support |
1786 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1600 | ev_embed_start (loop_hi, &embed); |
1841 | ev_embed_start (loop_hi, &embed); |
1601 | } |
1842 | } |
1602 | else |
1843 | else |
1603 | loop_lo = loop_hi; |
1844 | loop_lo = loop_hi; |
1604 | |
1845 | |
|
|
1846 | =head2 Portability notes |
|
|
1847 | |
|
|
1848 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
|
|
1849 | tried, in various ways. Usually the embedded event loop will simply never |
|
|
1850 | receive events, sometimes it will only trigger a few times, sometimes in a |
|
|
1851 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
|
|
1852 | will always eport the epoll fd as ready, even when no events are pending. |
|
|
1853 | |
|
|
1854 | While libev allows embedding these backends (they are contained in |
|
|
1855 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
|
|
1856 | work. |
|
|
1857 | |
|
|
1858 | When in doubt, create a dynamic event loop forced to use sockets (this |
|
|
1859 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1860 | your main event loop. |
|
|
1861 | |
|
|
1862 | =head3 Watcher-Specific Functions and Data Members |
|
|
1863 | |
1605 | =over 4 |
1864 | =over 4 |
1606 | |
1865 | |
1607 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1866 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1608 | |
1867 | |
1609 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1868 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1618 | |
1877 | |
1619 | Make a single, non-blocking sweep over the embedded loop. This works |
1878 | Make a single, non-blocking sweep over the embedded loop. This works |
1620 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1879 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1621 | apropriate way for embedded loops. |
1880 | apropriate way for embedded loops. |
1622 | |
1881 | |
1623 | =item struct ev_loop *loop [read-only] |
1882 | =item struct ev_loop *other [read-only] |
1624 | |
1883 | |
1625 | The embedded event loop. |
1884 | The embedded event loop. |
1626 | |
1885 | |
1627 | =back |
1886 | =back |
1628 | |
1887 | |
… | |
… | |
1635 | event loop blocks next and before C<ev_check> watchers are being called, |
1894 | event loop blocks next and before C<ev_check> watchers are being called, |
1636 | and only in the child after the fork. If whoever good citizen calling |
1895 | and only in the child after the fork. If whoever good citizen calling |
1637 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1896 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1638 | handlers will be invoked, too, of course. |
1897 | handlers will be invoked, too, of course. |
1639 | |
1898 | |
|
|
1899 | =head3 Watcher-Specific Functions and Data Members |
|
|
1900 | |
1640 | =over 4 |
1901 | =over 4 |
1641 | |
1902 | |
1642 | =item ev_fork_init (ev_signal *, callback) |
1903 | =item ev_fork_init (ev_signal *, callback) |
1643 | |
1904 | |
1644 | Initialises and configures the fork watcher - it has no parameters of any |
1905 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1740 | |
2001 | |
1741 | To use it, |
2002 | To use it, |
1742 | |
2003 | |
1743 | #include <ev++.h> |
2004 | #include <ev++.h> |
1744 | |
2005 | |
1745 | (it is not installed by default). This automatically includes F<ev.h> |
2006 | This automatically includes F<ev.h> and puts all of its definitions (many |
1746 | and puts all of its definitions (many of them macros) into the global |
2007 | of them macros) into the global namespace. All C++ specific things are |
1747 | namespace. All C++ specific things are put into the C<ev> namespace. |
2008 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2009 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1748 | |
2010 | |
1749 | It should support all the same embedding options as F<ev.h>, most notably |
2011 | Care has been taken to keep the overhead low. The only data member the C++ |
1750 | C<EV_MULTIPLICITY>. |
2012 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2013 | that the watcher is associated with (or no additional members at all if |
|
|
2014 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2015 | |
|
|
2016 | Currently, functions, and static and non-static member functions can be |
|
|
2017 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2018 | need one additional pointer for context. If you need support for other |
|
|
2019 | types of functors please contact the author (preferably after implementing |
|
|
2020 | it). |
1751 | |
2021 | |
1752 | Here is a list of things available in the C<ev> namespace: |
2022 | Here is a list of things available in the C<ev> namespace: |
1753 | |
2023 | |
1754 | =over 4 |
2024 | =over 4 |
1755 | |
2025 | |
… | |
… | |
1771 | |
2041 | |
1772 | All of those classes have these methods: |
2042 | All of those classes have these methods: |
1773 | |
2043 | |
1774 | =over 4 |
2044 | =over 4 |
1775 | |
2045 | |
1776 | =item ev::TYPE::TYPE (object *, object::method *) |
2046 | =item ev::TYPE::TYPE () |
1777 | |
2047 | |
1778 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2048 | =item ev::TYPE::TYPE (struct ev_loop *) |
1779 | |
2049 | |
1780 | =item ev::TYPE::~TYPE |
2050 | =item ev::TYPE::~TYPE |
1781 | |
2051 | |
1782 | The constructor takes a pointer to an object and a method pointer to |
2052 | The constructor (optionally) takes an event loop to associate the watcher |
1783 | the event handler callback to call in this class. The constructor calls |
2053 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1784 | C<ev_init> for you, which means you have to call the C<set> method |
2054 | |
1785 | before starting it. If you do not specify a loop then the constructor |
2055 | The constructor calls C<ev_init> for you, which means you have to call the |
1786 | automatically associates the default loop with this watcher. |
2056 | C<set> method before starting it. |
|
|
2057 | |
|
|
2058 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2059 | method to set a callback before you can start the watcher. |
|
|
2060 | |
|
|
2061 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2062 | not allow explicit template arguments for constructors). |
1787 | |
2063 | |
1788 | The destructor automatically stops the watcher if it is active. |
2064 | The destructor automatically stops the watcher if it is active. |
|
|
2065 | |
|
|
2066 | =item w->set<class, &class::method> (object *) |
|
|
2067 | |
|
|
2068 | This method sets the callback method to call. The method has to have a |
|
|
2069 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2070 | first argument and the C<revents> as second. The object must be given as |
|
|
2071 | parameter and is stored in the C<data> member of the watcher. |
|
|
2072 | |
|
|
2073 | This method synthesizes efficient thunking code to call your method from |
|
|
2074 | the C callback that libev requires. If your compiler can inline your |
|
|
2075 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2076 | your compiler is good :), then the method will be fully inlined into the |
|
|
2077 | thunking function, making it as fast as a direct C callback. |
|
|
2078 | |
|
|
2079 | Example: simple class declaration and watcher initialisation |
|
|
2080 | |
|
|
2081 | struct myclass |
|
|
2082 | { |
|
|
2083 | void io_cb (ev::io &w, int revents) { } |
|
|
2084 | } |
|
|
2085 | |
|
|
2086 | myclass obj; |
|
|
2087 | ev::io iow; |
|
|
2088 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2089 | |
|
|
2090 | =item w->set<function> (void *data = 0) |
|
|
2091 | |
|
|
2092 | Also sets a callback, but uses a static method or plain function as |
|
|
2093 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2094 | C<data> member and is free for you to use. |
|
|
2095 | |
|
|
2096 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2097 | |
|
|
2098 | See the method-C<set> above for more details. |
|
|
2099 | |
|
|
2100 | Example: |
|
|
2101 | |
|
|
2102 | static void io_cb (ev::io &w, int revents) { } |
|
|
2103 | iow.set <io_cb> (); |
1789 | |
2104 | |
1790 | =item w->set (struct ev_loop *) |
2105 | =item w->set (struct ev_loop *) |
1791 | |
2106 | |
1792 | Associates a different C<struct ev_loop> with this watcher. You can only |
2107 | Associates a different C<struct ev_loop> with this watcher. You can only |
1793 | do this when the watcher is inactive (and not pending either). |
2108 | do this when the watcher is inactive (and not pending either). |
1794 | |
2109 | |
1795 | =item w->set ([args]) |
2110 | =item w->set ([args]) |
1796 | |
2111 | |
1797 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2112 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1798 | called at least once. Unlike the C counterpart, an active watcher gets |
2113 | called at least once. Unlike the C counterpart, an active watcher gets |
1799 | automatically stopped and restarted. |
2114 | automatically stopped and restarted when reconfiguring it with this |
|
|
2115 | method. |
1800 | |
2116 | |
1801 | =item w->start () |
2117 | =item w->start () |
1802 | |
2118 | |
1803 | Starts the watcher. Note that there is no C<loop> argument as the |
2119 | Starts the watcher. Note that there is no C<loop> argument, as the |
1804 | constructor already takes the loop. |
2120 | constructor already stores the event loop. |
1805 | |
2121 | |
1806 | =item w->stop () |
2122 | =item w->stop () |
1807 | |
2123 | |
1808 | Stops the watcher if it is active. Again, no C<loop> argument. |
2124 | Stops the watcher if it is active. Again, no C<loop> argument. |
1809 | |
2125 | |
1810 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2126 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1811 | |
2127 | |
1812 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2128 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1813 | C<ev_TYPE_again> function. |
2129 | C<ev_TYPE_again> function. |
1814 | |
2130 | |
1815 | =item w->sweep () C<ev::embed> only |
2131 | =item w->sweep () (C<ev::embed> only) |
1816 | |
2132 | |
1817 | Invokes C<ev_embed_sweep>. |
2133 | Invokes C<ev_embed_sweep>. |
1818 | |
2134 | |
1819 | =item w->update () C<ev::stat> only |
2135 | =item w->update () (C<ev::stat> only) |
1820 | |
2136 | |
1821 | Invokes C<ev_stat_stat>. |
2137 | Invokes C<ev_stat_stat>. |
1822 | |
2138 | |
1823 | =back |
2139 | =back |
1824 | |
2140 | |
… | |
… | |
1834 | |
2150 | |
1835 | myclass (); |
2151 | myclass (); |
1836 | } |
2152 | } |
1837 | |
2153 | |
1838 | myclass::myclass (int fd) |
2154 | myclass::myclass (int fd) |
1839 | : io (this, &myclass::io_cb), |
|
|
1840 | idle (this, &myclass::idle_cb) |
|
|
1841 | { |
2155 | { |
|
|
2156 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2157 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2158 | |
1842 | io.start (fd, ev::READ); |
2159 | io.start (fd, ev::READ); |
1843 | } |
2160 | } |
1844 | |
2161 | |
1845 | |
2162 | |
1846 | =head1 MACRO MAGIC |
2163 | =head1 MACRO MAGIC |
1847 | |
2164 | |
1848 | Libev can be compiled with a variety of options, the most fundemantal is |
2165 | Libev can be compiled with a variety of options, the most fundamantal |
1849 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2166 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1850 | callbacks have an initial C<struct ev_loop *> argument. |
2167 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1851 | |
2168 | |
1852 | To make it easier to write programs that cope with either variant, the |
2169 | To make it easier to write programs that cope with either variant, the |
1853 | following macros are defined: |
2170 | following macros are defined: |
1854 | |
2171 | |
1855 | =over 4 |
2172 | =over 4 |
… | |
… | |
1909 | Libev can (and often is) directly embedded into host |
2226 | Libev can (and often is) directly embedded into host |
1910 | applications. Examples of applications that embed it include the Deliantra |
2227 | applications. Examples of applications that embed it include the Deliantra |
1911 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2228 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1912 | and rxvt-unicode. |
2229 | and rxvt-unicode. |
1913 | |
2230 | |
1914 | The goal is to enable you to just copy the neecssary files into your |
2231 | The goal is to enable you to just copy the necessary files into your |
1915 | source directory without having to change even a single line in them, so |
2232 | source directory without having to change even a single line in them, so |
1916 | you can easily upgrade by simply copying (or having a checked-out copy of |
2233 | you can easily upgrade by simply copying (or having a checked-out copy of |
1917 | libev somewhere in your source tree). |
2234 | libev somewhere in your source tree). |
1918 | |
2235 | |
1919 | =head2 FILESETS |
2236 | =head2 FILESETS |
… | |
… | |
2009 | |
2326 | |
2010 | If defined to be C<1>, libev will try to detect the availability of the |
2327 | If defined to be C<1>, libev will try to detect the availability of the |
2011 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2328 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2012 | of the monotonic clock option will be attempted. If you enable this, you |
2329 | of the monotonic clock option will be attempted. If you enable this, you |
2013 | usually have to link against librt or something similar. Enabling it when |
2330 | usually have to link against librt or something similar. Enabling it when |
2014 | the functionality isn't available is safe, though, althoguh you have |
2331 | the functionality isn't available is safe, though, although you have |
2015 | to make sure you link against any libraries where the C<clock_gettime> |
2332 | to make sure you link against any libraries where the C<clock_gettime> |
2016 | function is hiding in (often F<-lrt>). |
2333 | function is hiding in (often F<-lrt>). |
2017 | |
2334 | |
2018 | =item EV_USE_REALTIME |
2335 | =item EV_USE_REALTIME |
2019 | |
2336 | |
2020 | If defined to be C<1>, libev will try to detect the availability of the |
2337 | If defined to be C<1>, libev will try to detect the availability of the |
2021 | realtime clock option at compiletime (and assume its availability at |
2338 | realtime clock option at compiletime (and assume its availability at |
2022 | runtime if successful). Otherwise no use of the realtime clock option will |
2339 | runtime if successful). Otherwise no use of the realtime clock option will |
2023 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2340 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2024 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2341 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2025 | in the description of C<EV_USE_MONOTONIC>, though. |
2342 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2343 | |
|
|
2344 | =item EV_USE_NANOSLEEP |
|
|
2345 | |
|
|
2346 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2347 | and will use it for delays. Otherwise it will use C<select ()>. |
2026 | |
2348 | |
2027 | =item EV_USE_SELECT |
2349 | =item EV_USE_SELECT |
2028 | |
2350 | |
2029 | If undefined or defined to be C<1>, libev will compile in support for the |
2351 | If undefined or defined to be C<1>, libev will compile in support for the |
2030 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2352 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2123 | will have the C<struct ev_loop *> as first argument, and you can create |
2445 | will have the C<struct ev_loop *> as first argument, and you can create |
2124 | additional independent event loops. Otherwise there will be no support |
2446 | additional independent event loops. Otherwise there will be no support |
2125 | for multiple event loops and there is no first event loop pointer |
2447 | for multiple event loops and there is no first event loop pointer |
2126 | argument. Instead, all functions act on the single default loop. |
2448 | argument. Instead, all functions act on the single default loop. |
2127 | |
2449 | |
|
|
2450 | =item EV_MINPRI |
|
|
2451 | |
|
|
2452 | =item EV_MAXPRI |
|
|
2453 | |
|
|
2454 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2455 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2456 | provide for more priorities by overriding those symbols (usually defined |
|
|
2457 | to be C<-2> and C<2>, respectively). |
|
|
2458 | |
|
|
2459 | When doing priority-based operations, libev usually has to linearly search |
|
|
2460 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2461 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2462 | fine. |
|
|
2463 | |
|
|
2464 | If your embedding app does not need any priorities, defining these both to |
|
|
2465 | C<0> will save some memory and cpu. |
|
|
2466 | |
2128 | =item EV_PERIODIC_ENABLE |
2467 | =item EV_PERIODIC_ENABLE |
2129 | |
2468 | |
2130 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2469 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2131 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2470 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2132 | code. |
2471 | code. |
… | |
… | |
2192 | |
2531 | |
2193 | =item ev_set_cb (ev, cb) |
2532 | =item ev_set_cb (ev, cb) |
2194 | |
2533 | |
2195 | Can be used to change the callback member declaration in each watcher, |
2534 | Can be used to change the callback member declaration in each watcher, |
2196 | and the way callbacks are invoked and set. Must expand to a struct member |
2535 | and the way callbacks are invoked and set. Must expand to a struct member |
2197 | definition and a statement, respectively. See the F<ev.v> header file for |
2536 | definition and a statement, respectively. See the F<ev.h> header file for |
2198 | their default definitions. One possible use for overriding these is to |
2537 | their default definitions. One possible use for overriding these is to |
2199 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2538 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2200 | method calls instead of plain function calls in C++. |
2539 | method calls instead of plain function calls in C++. |
|
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2540 | |
|
|
2541 | =head2 EXPORTED API SYMBOLS |
|
|
2542 | |
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|
2543 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2544 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
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2545 | all public symbols, one per line: |
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2546 | |
|
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2547 | Symbols.ev for libev proper |
|
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2548 | Symbols.event for the libevent emulation |
|
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2549 | |
|
|
2550 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2551 | multiple versions of libev linked together (which is obviously bad in |
|
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2552 | itself, but sometimes it is inconvinient to avoid this). |
|
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2553 | |
|
|
2554 | A sed command like this will create wrapper C<#define>'s that you need to |
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2555 | include before including F<ev.h>: |
|
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2556 | |
|
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2557 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
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2558 | |
|
|
2559 | This would create a file F<wrap.h> which essentially looks like this: |
|
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2560 | |
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2561 | #define ev_backend myprefix_ev_backend |
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2562 | #define ev_check_start myprefix_ev_check_start |
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2563 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2564 | ... |
2201 | |
2565 | |
2202 | =head2 EXAMPLES |
2566 | =head2 EXAMPLES |
2203 | |
2567 | |
2204 | For a real-world example of a program the includes libev |
2568 | For a real-world example of a program the includes libev |
2205 | verbatim, you can have a look at the EV perl module |
2569 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2234 | |
2598 | |
2235 | In this section the complexities of (many of) the algorithms used inside |
2599 | In this section the complexities of (many of) the algorithms used inside |
2236 | libev will be explained. For complexity discussions about backends see the |
2600 | libev will be explained. For complexity discussions about backends see the |
2237 | documentation for C<ev_default_init>. |
2601 | documentation for C<ev_default_init>. |
2238 | |
2602 | |
|
|
2603 | All of the following are about amortised time: If an array needs to be |
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|
2604 | extended, libev needs to realloc and move the whole array, but this |
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|
2605 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2606 | mean it might do a lengthy realloc operation in rare cases, but on average |
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2607 | it is much faster and asymptotically approaches constant time. |
|
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2608 | |
2239 | =over 4 |
2609 | =over 4 |
2240 | |
2610 | |
2241 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2611 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2242 | |
2612 | |
|
|
2613 | This means that, when you have a watcher that triggers in one hour and |
|
|
2614 | there are 100 watchers that would trigger before that then inserting will |
|
|
2615 | have to skip those 100 watchers. |
|
|
2616 | |
2243 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2617 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2244 | |
2618 | |
|
|
2619 | That means that for changing a timer costs less than removing/adding them |
|
|
2620 | as only the relative motion in the event queue has to be paid for. |
|
|
2621 | |
2245 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2622 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2246 | |
2623 | |
|
|
2624 | These just add the watcher into an array or at the head of a list. |
2247 | =item Stopping check/prepare/idle watchers: O(1) |
2625 | =item Stopping check/prepare/idle watchers: O(1) |
2248 | |
2626 | |
2249 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2627 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2250 | |
2628 | |
|
|
2629 | These watchers are stored in lists then need to be walked to find the |
|
|
2630 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2631 | have many watchers waiting for the same fd or signal). |
|
|
2632 | |
2251 | =item Finding the next timer per loop iteration: O(1) |
2633 | =item Finding the next timer per loop iteration: O(1) |
2252 | |
2634 | |
2253 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2635 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2254 | |
2636 | |
|
|
2637 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2638 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2639 | |
2255 | =item Activating one watcher: O(1) |
2640 | =item Activating one watcher: O(1) |
2256 | |
2641 | |
|
|
2642 | =item Priority handling: O(number_of_priorities) |
|
|
2643 | |
|
|
2644 | Priorities are implemented by allocating some space for each |
|
|
2645 | priority. When doing priority-based operations, libev usually has to |
|
|
2646 | linearly search all the priorities. |
|
|
2647 | |
2257 | =back |
2648 | =back |
2258 | |
2649 | |
2259 | |
2650 | |
2260 | =head1 AUTHOR |
2651 | =head1 AUTHOR |
2261 | |
2652 | |