… | |
… | |
115 | |
115 | |
116 | Returns the current time as libev would use it. Please note that the |
116 | Returns the current time as libev would use it. Please note that the |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
118 | you actually want to know. |
118 | you actually want to know. |
119 | |
119 | |
|
|
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 | |
120 | =item int ev_version_major () |
126 | =item int ev_version_major () |
121 | |
127 | |
122 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
123 | |
129 | |
124 | You can find out the major and minor ABI version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
… | |
… | |
317 | 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, |
318 | but it scales phenomenally better. While poll and select usually scale |
324 | but it scales phenomenally better. While poll and select usually scale |
319 | like O(total_fds) where n is the total number of fds (or the highest fd), |
325 | like O(total_fds) where n is the total number of fds (or the highest fd), |
320 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
326 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
321 | of shortcomings, such as silently dropping events in some hard-to-detect |
327 | of shortcomings, such as silently dropping events in some hard-to-detect |
322 | cases and rewuiring a syscall per fd change, no fork support and bad |
328 | cases and rewiring a syscall per fd change, no fork support and bad |
323 | support for dup: |
329 | support for dup: |
324 | |
330 | |
325 | While stopping, setting and starting an I/O watcher in the same iteration |
331 | While stopping, setting and starting an I/O watcher in the same iteration |
326 | will result in some caching, there is still a syscall per such incident |
332 | will result in some caching, there is still a syscall per such incident |
327 | (because the fd could point to a different file description now), so its |
333 | (because the fd could point to a different file description now), so its |
… | |
… | |
333 | (or space) is available. |
339 | (or space) is available. |
334 | |
340 | |
335 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
341 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
336 | |
342 | |
337 | 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 |
338 | was broken on I<all> BSDs (usually it doesn't work with anything but |
344 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
339 | sockets and pipes, except on Darwin, where of course it's completely |
345 | with anything but sockets and pipes, except on Darwin, where of course |
340 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
|
|
341 | is used by default there). For this reason it's not being "autodetected" |
346 | it's completely useless). For this reason it's not being "autodetected" |
342 | unless you explicitly specify it explicitly in the flags (i.e. using |
347 | unless you explicitly specify it explicitly in the flags (i.e. using |
343 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
348 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
344 | system like NetBSD. |
349 | system like NetBSD. |
345 | |
350 | |
|
|
351 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
352 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
353 | the target platform). See C<ev_embed> watchers for more info. |
|
|
354 | |
346 | It scales in the same way as the epoll backend, but the interface to the |
355 | It scales in the same way as the epoll backend, but the interface to the |
347 | kernel is more efficient (which says nothing about its actual speed, |
356 | kernel is more efficient (which says nothing about its actual speed, of |
348 | of course). While stopping, setting and starting an I/O watcher does |
357 | course). While stopping, setting and starting an I/O watcher does never |
349 | never cause an extra syscall as with epoll, it still adds up to two event |
358 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
350 | changes per incident, support for C<fork ()> is very bad and it drops fds |
359 | two event changes per incident, support for C<fork ()> is very bad and it |
351 | silently in similarly hard-to-detetc cases. |
360 | drops fds silently in similarly hard-to-detect cases. |
352 | |
361 | |
353 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
362 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
354 | |
363 | |
355 | This is not implemented yet (and might never be). |
364 | This is not implemented yet (and might never be). |
356 | |
365 | |
… | |
… | |
569 | Example: For some weird reason, unregister the above signal handler again. |
578 | Example: For some weird reason, unregister the above signal handler again. |
570 | |
579 | |
571 | ev_ref (loop); |
580 | ev_ref (loop); |
572 | ev_signal_stop (loop, &exitsig); |
581 | ev_signal_stop (loop, &exitsig); |
573 | |
582 | |
|
|
583 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
584 | |
|
|
585 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
586 | |
|
|
587 | These advanced functions influence the time that libev will spend waiting |
|
|
588 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
589 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
590 | |
|
|
591 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
592 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
593 | increase efficiency of loop iterations. |
|
|
594 | |
|
|
595 | The background is that sometimes your program runs just fast enough to |
|
|
596 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
597 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
598 | events, especially with backends like C<select ()> which have a high |
|
|
599 | overhead for the actual polling but can deliver many events at once. |
|
|
600 | |
|
|
601 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
602 | time collecting I/O events, so you can handle more events per iteration, |
|
|
603 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
604 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
605 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
606 | |
|
|
607 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
608 | to spend more time collecting timeouts, at the expense of increased |
|
|
609 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
610 | will not be affected. Setting this to a non-null value will not introduce |
|
|
611 | any overhead in libev. |
|
|
612 | |
|
|
613 | Many (busy) programs can usually benefit by setting the io collect |
|
|
614 | interval to a value near C<0.1> or so, which is often enough for |
|
|
615 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
616 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
617 | as this approsaches the timing granularity of most systems. |
|
|
618 | |
574 | =back |
619 | =back |
575 | |
620 | |
576 | |
621 | |
577 | =head1 ANATOMY OF A WATCHER |
622 | =head1 ANATOMY OF A WATCHER |
578 | |
623 | |
… | |
… | |
949 | |
994 | |
950 | This is how one would do it normally anyway, the important point is that |
995 | This is how one would do it normally anyway, the important point is that |
951 | the libev application should not optimise around libev but should leave |
996 | the libev application should not optimise around libev but should leave |
952 | optimisations to libev. |
997 | optimisations to libev. |
953 | |
998 | |
954 | =head3 Ths special problem of dup'ed file descriptors |
999 | =head3 The special problem of dup'ed file descriptors |
955 | |
1000 | |
956 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1001 | Some backends (e.g. epoll), cannot register events for file descriptors, |
957 | but only events for the underlying file descriptions. That menas when you |
1002 | but only events for the underlying file descriptions. That menas when you |
958 | have C<dup ()>'ed file descriptors and register events for them, only one |
1003 | have C<dup ()>'ed file descriptors and register events for them, only one |
959 | file descriptor might actually receive events. |
1004 | file descriptor might actually receive events. |
… | |
… | |
1581 | |
1626 | |
1582 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1627 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1583 | priority, to ensure that they are being run before any other watchers |
1628 | priority, to ensure that they are being run before any other watchers |
1584 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1629 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1585 | too) should not activate ("feed") events into libev. While libev fully |
1630 | too) should not activate ("feed") events into libev. While libev fully |
1586 | supports this, they will be called before other C<ev_check> watchers did |
1631 | supports this, they will be called before other C<ev_check> watchers |
1587 | their job. As C<ev_check> watchers are often used to embed other event |
1632 | did their job. As C<ev_check> watchers are often used to embed other |
1588 | loops those other event loops might be in an unusable state until their |
1633 | (non-libev) event loops those other event loops might be in an unusable |
1589 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1634 | state until their C<ev_check> watcher ran (always remind yourself to |
1590 | others). |
1635 | coexist peacefully with others). |
1591 | |
1636 | |
1592 | =head3 Watcher-Specific Functions and Data Members |
1637 | =head3 Watcher-Specific Functions and Data Members |
1593 | |
1638 | |
1594 | =over 4 |
1639 | =over 4 |
1595 | |
1640 | |
… | |
… | |
1734 | =head2 C<ev_embed> - when one backend isn't enough... |
1779 | =head2 C<ev_embed> - when one backend isn't enough... |
1735 | |
1780 | |
1736 | This is a rather advanced watcher type that lets you embed one event loop |
1781 | This is a rather advanced watcher type that lets you embed one event loop |
1737 | into another (currently only C<ev_io> events are supported in the embedded |
1782 | into another (currently only C<ev_io> events are supported in the embedded |
1738 | loop, other types of watchers might be handled in a delayed or incorrect |
1783 | loop, other types of watchers might be handled in a delayed or incorrect |
1739 | fashion and must not be used). (See portability notes, below). |
1784 | fashion and must not be used). |
1740 | |
1785 | |
1741 | There are primarily two reasons you would want that: work around bugs and |
1786 | There are primarily two reasons you would want that: work around bugs and |
1742 | prioritise I/O. |
1787 | prioritise I/O. |
1743 | |
1788 | |
1744 | As an example for a bug workaround, the kqueue backend might only support |
1789 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1799 | ev_embed_start (loop_hi, &embed); |
1844 | ev_embed_start (loop_hi, &embed); |
1800 | } |
1845 | } |
1801 | else |
1846 | else |
1802 | loop_lo = loop_hi; |
1847 | loop_lo = loop_hi; |
1803 | |
1848 | |
1804 | =head2 Portability notes |
|
|
1805 | |
|
|
1806 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
|
|
1807 | tried, in various ways. Usually the embedded event loop will simply never |
|
|
1808 | receive events, sometimes it will only trigger a few times, sometimes in a |
|
|
1809 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
|
|
1810 | will always eport the epoll fd as ready, even when no events are pending. |
|
|
1811 | |
|
|
1812 | While libev allows embedding these backends (they are contained in |
|
|
1813 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
|
|
1814 | work. |
|
|
1815 | |
|
|
1816 | When in doubt, create a dynamic event loop forced to use sockets (this |
|
|
1817 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1818 | your main event loop. |
|
|
1819 | |
|
|
1820 | =head3 Watcher-Specific Functions and Data Members |
1849 | =head3 Watcher-Specific Functions and Data Members |
1821 | |
1850 | |
1822 | =over 4 |
1851 | =over 4 |
1823 | |
1852 | |
1824 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1853 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
2296 | realtime clock option at compiletime (and assume its availability at |
2325 | realtime clock option at compiletime (and assume its availability at |
2297 | runtime if successful). Otherwise no use of the realtime clock option will |
2326 | runtime if successful). Otherwise no use of the realtime clock option will |
2298 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2327 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2299 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2328 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2300 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2329 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2330 | |
|
|
2331 | =item EV_USE_NANOSLEEP |
|
|
2332 | |
|
|
2333 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2334 | and will use it for delays. Otherwise it will use C<select ()>. |
2301 | |
2335 | |
2302 | =item EV_USE_SELECT |
2336 | =item EV_USE_SELECT |
2303 | |
2337 | |
2304 | If undefined or defined to be C<1>, libev will compile in support for the |
2338 | If undefined or defined to be C<1>, libev will compile in support for the |
2305 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2339 | C<select>(2) backend. No attempt at autodetection will be done: if no |