… | |
… | |
105 | details of the event, and then hand it over to libev by I<starting> the |
105 | details of the event, and then hand it over to libev by I<starting> the |
106 | watcher. |
106 | watcher. |
107 | |
107 | |
108 | =head2 FEATURES |
108 | =head2 FEATURES |
109 | |
109 | |
110 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
110 | Libev supports C<select>, C<poll>, the Linux-specific aio and C<epoll> |
111 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
111 | interfaces, the BSD-specific C<kqueue> and the Solaris-specific event port |
112 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
112 | mechanisms for file descriptor events (C<ev_io>), the Linux C<inotify> |
113 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
113 | interface (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
114 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
114 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
115 | timers (C<ev_timer>), absolute timers with customised rescheduling |
115 | timers (C<ev_timer>), absolute timers with customised rescheduling |
116 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
116 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
117 | change events (C<ev_child>), and event watchers dealing with the event |
117 | change events (C<ev_child>), and event watchers dealing with the event |
118 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
118 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
… | |
… | |
159 | When libev detects a usage error such as a negative timer interval, then |
159 | When libev detects a usage error such as a negative timer interval, then |
160 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
160 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
161 | so C<NDEBUG> will disable this checking): these are programming errors in |
161 | so C<NDEBUG> will disable this checking): these are programming errors in |
162 | the libev caller and need to be fixed there. |
162 | the libev caller and need to be fixed there. |
163 | |
163 | |
|
|
164 | Via the C<EV_FREQUENT> macro you can compile in and/or enable extensive |
|
|
165 | consistency checking code inside libev that can be used to check for |
|
|
166 | internal inconsistencies, suually caused by application bugs. |
|
|
167 | |
164 | Libev also has a few internal error-checking C<assert>ions, and also has |
168 | Libev also has a few internal error-checking C<assert>ions. These do not |
165 | extensive consistency checking code. These do not trigger under normal |
|
|
166 | circumstances, as they indicate either a bug in libev or worse. |
169 | trigger under normal circumstances, as they indicate either a bug in libev |
|
|
170 | or worse. |
167 | |
171 | |
168 | |
172 | |
169 | =head1 GLOBAL FUNCTIONS |
173 | =head1 GLOBAL FUNCTIONS |
170 | |
174 | |
171 | These functions can be called anytime, even before initialising the |
175 | These functions can be called anytime, even before initialising the |
… | |
… | |
265 | |
269 | |
266 | You could override this function in high-availability programs to, say, |
270 | You could override this function in high-availability programs to, say, |
267 | free some memory if it cannot allocate memory, to use a special allocator, |
271 | free some memory if it cannot allocate memory, to use a special allocator, |
268 | or even to sleep a while and retry until some memory is available. |
272 | or even to sleep a while and retry until some memory is available. |
269 | |
273 | |
|
|
274 | Example: The following is the C<realloc> function that libev itself uses |
|
|
275 | which should work with C<realloc> and C<free> functions of all kinds and |
|
|
276 | is probably a good basis for your own implementation. |
|
|
277 | |
|
|
278 | static void * |
|
|
279 | ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
|
|
280 | { |
|
|
281 | if (size) |
|
|
282 | return realloc (ptr, size); |
|
|
283 | |
|
|
284 | free (ptr); |
|
|
285 | return 0; |
|
|
286 | } |
|
|
287 | |
270 | Example: Replace the libev allocator with one that waits a bit and then |
288 | Example: Replace the libev allocator with one that waits a bit and then |
271 | retries (example requires a standards-compliant C<realloc>). |
289 | retries. |
272 | |
290 | |
273 | static void * |
291 | static void * |
274 | persistent_realloc (void *ptr, size_t size) |
292 | persistent_realloc (void *ptr, size_t size) |
275 | { |
293 | { |
|
|
294 | if (!size) |
|
|
295 | { |
|
|
296 | free (ptr); |
|
|
297 | return 0; |
|
|
298 | } |
|
|
299 | |
276 | for (;;) |
300 | for (;;) |
277 | { |
301 | { |
278 | void *newptr = realloc (ptr, size); |
302 | void *newptr = realloc (ptr, size); |
279 | |
303 | |
280 | if (newptr) |
304 | if (newptr) |
… | |
… | |
456 | unblocking the signals. |
480 | unblocking the signals. |
457 | |
481 | |
458 | It's also required by POSIX in a threaded program, as libev calls |
482 | It's also required by POSIX in a threaded program, as libev calls |
459 | C<sigprocmask>, whose behaviour is officially unspecified. |
483 | C<sigprocmask>, whose behaviour is officially unspecified. |
460 | |
484 | |
461 | This flag's behaviour will become the default in future versions of libev. |
485 | =item C<EVFLAG_NOTIMERFD> |
|
|
486 | |
|
|
487 | When this flag is specified, the libev will avoid using a C<timerfd> to |
|
|
488 | detect time jumps. It will still be able to detect time jumps, but takes |
|
|
489 | longer and has a lower accuracy in doing so, but saves a file descriptor |
|
|
490 | per loop. |
|
|
491 | |
|
|
492 | The current implementation only tries to use a C<timerfd> when the first |
|
|
493 | C<ev_periodic> watcher is started and falls back on other methods if it |
|
|
494 | cannot be created, but this behaviour might change in the future. |
462 | |
495 | |
463 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
496 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
464 | |
497 | |
465 | This is your standard select(2) backend. Not I<completely> standard, as |
498 | This is your standard select(2) backend. Not I<completely> standard, as |
466 | libev tries to roll its own fd_set with no limits on the number of fds, |
499 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
491 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
524 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
492 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
525 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
493 | |
526 | |
494 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
527 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
495 | |
528 | |
496 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
529 | Use the Linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
497 | kernels). |
530 | kernels). |
498 | |
531 | |
499 | For few fds, this backend is a bit little slower than poll and select, but |
532 | For few fds, this backend is a bit little slower than poll and select, but |
500 | it scales phenomenally better. While poll and select usually scale like |
533 | it scales phenomenally better. While poll and select usually scale like |
501 | O(total_fds) where total_fds is the total number of fds (or the highest |
534 | O(total_fds) where total_fds is the total number of fds (or the highest |
… | |
… | |
547 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
580 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
548 | faster than epoll for maybe up to a hundred file descriptors, depending on |
581 | faster than epoll for maybe up to a hundred file descriptors, depending on |
549 | the usage. So sad. |
582 | the usage. So sad. |
550 | |
583 | |
551 | While nominally embeddable in other event loops, this feature is broken in |
584 | While nominally embeddable in other event loops, this feature is broken in |
552 | all kernel versions tested so far. |
585 | a lot of kernel revisions, but probably(!) works in current versions. |
553 | |
586 | |
554 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
587 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
555 | C<EVBACKEND_POLL>. |
588 | C<EVBACKEND_POLL>. |
556 | |
589 | |
|
|
590 | =item C<EVBACKEND_LINUXAIO> (value 64, Linux) |
|
|
591 | |
|
|
592 | Use the Linux-specific Linux AIO (I<not> C<< aio(7) >> but C<< |
|
|
593 | io_submit(2) >>) event interface available in post-4.18 kernels (but libev |
|
|
594 | only tries to use it in 4.19+). |
|
|
595 | |
|
|
596 | This is another Linux train wreck of an event interface. |
|
|
597 | |
|
|
598 | If this backend works for you (as of this writing, it was very |
|
|
599 | experimental), it is the best event interface available on Linux and might |
|
|
600 | be well worth enabling it - if it isn't available in your kernel this will |
|
|
601 | be detected and this backend will be skipped. |
|
|
602 | |
|
|
603 | This backend can batch oneshot requests and supports a user-space ring |
|
|
604 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
605 | problems of epoll (such as not being able to remove event sources from |
|
|
606 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
607 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
608 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
609 | issues. |
|
|
610 | |
|
|
611 | For one, it is not easily embeddable (but probably could be done using |
|
|
612 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
613 | limit that can be configured in F</proc/sys/fs/aio-max-nr>. If no AIO |
|
|
614 | requests are left, this backend will be skipped during initialisation, and |
|
|
615 | will switch to epoll when the loop is active. |
|
|
616 | |
|
|
617 | Most problematic in practice, however, is that not all file descriptors |
|
|
618 | work with it. For example, in Linux 5.1, TCP sockets, pipes, event fds, |
|
|
619 | files, F</dev/null> and many others are supported, but ttys do not work |
|
|
620 | properly (a known bug that the kernel developers don't care about, see |
|
|
621 | L<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
622 | (yet?) a generic event polling interface. |
|
|
623 | |
|
|
624 | Overall, it seems the Linux developers just don't want it to have a |
|
|
625 | generic event handling mechanism other than C<select> or C<poll>. |
|
|
626 | |
|
|
627 | To work around all these problem, the current version of libev uses its |
|
|
628 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
629 | falls back completely to epoll if the kernel acts up. |
|
|
630 | |
|
|
631 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
|
|
632 | C<EVBACKEND_POLL>. |
|
|
633 | |
557 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
634 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
558 | |
635 | |
559 | Kqueue deserves special mention, as at the time of this writing, it |
636 | Kqueue deserves special mention, as at the time this backend was |
560 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
637 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
561 | with anything but sockets and pipes, except on Darwin, where of course |
638 | work reliably with anything but sockets and pipes, except on Darwin, |
562 | it's completely useless). Unlike epoll, however, whose brokenness |
639 | where of course it's completely useless). Unlike epoll, however, whose |
563 | is by design, these kqueue bugs can (and eventually will) be fixed |
640 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
564 | without API changes to existing programs. For this reason it's not being |
641 | fixed without API changes to existing programs. For this reason it's not |
565 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
642 | being "auto-detected" on all platforms unless you explicitly specify it |
566 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
643 | in the flags (i.e. using C<EVBACKEND_KQUEUE>) or libev was compiled on a |
567 | system like NetBSD. |
644 | known-to-be-good (-enough) system like NetBSD. |
568 | |
645 | |
569 | You still can embed kqueue into a normal poll or select backend and use it |
646 | You still can embed kqueue into a normal poll or select backend and use it |
570 | only for sockets (after having made sure that sockets work with kqueue on |
647 | only for sockets (after having made sure that sockets work with kqueue on |
571 | the target platform). See C<ev_embed> watchers for more info. |
648 | the target platform). See C<ev_embed> watchers for more info. |
572 | |
649 | |
573 | It scales in the same way as the epoll backend, but the interface to the |
650 | It scales in the same way as the epoll backend, but the interface to the |
574 | kernel is more efficient (which says nothing about its actual speed, of |
651 | kernel is more efficient (which says nothing about its actual speed, of |
575 | course). While stopping, setting and starting an I/O watcher does never |
652 | course). While stopping, setting and starting an I/O watcher does never |
576 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
653 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
577 | two event changes per incident. Support for C<fork ()> is very bad (you |
654 | two event changes per incident. Support for C<fork ()> is very bad (you |
578 | might have to leak fd's on fork, but it's more sane than epoll) and it |
655 | might have to leak fds on fork, but it's more sane than epoll) and it |
579 | drops fds silently in similarly hard-to-detect cases. |
656 | drops fds silently in similarly hard-to-detect cases. |
580 | |
657 | |
581 | This backend usually performs well under most conditions. |
658 | This backend usually performs well under most conditions. |
582 | |
659 | |
583 | While nominally embeddable in other event loops, this doesn't work |
660 | While nominally embeddable in other event loops, this doesn't work |
… | |
… | |
657 | |
734 | |
658 | Example: Use whatever libev has to offer, but make sure that kqueue is |
735 | Example: Use whatever libev has to offer, but make sure that kqueue is |
659 | used if available. |
736 | used if available. |
660 | |
737 | |
661 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
738 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
739 | |
|
|
740 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
741 | linux aio backend if possible, but fall back to something else if that |
|
|
742 | isn't available. |
|
|
743 | |
|
|
744 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
662 | |
745 | |
663 | =item ev_loop_destroy (loop) |
746 | =item ev_loop_destroy (loop) |
664 | |
747 | |
665 | Destroys an event loop object (frees all memory and kernel state |
748 | Destroys an event loop object (frees all memory and kernel state |
666 | etc.). None of the active event watchers will be stopped in the normal |
749 | etc.). None of the active event watchers will be stopped in the normal |
… | |
… | |
1135 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
1218 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
1136 | *) >>), and you can stop watching for events at any time by calling the |
1219 | *) >>), and you can stop watching for events at any time by calling the |
1137 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
1220 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
1138 | |
1221 | |
1139 | As long as your watcher is active (has been started but not stopped) you |
1222 | As long as your watcher is active (has been started but not stopped) you |
1140 | must not touch the values stored in it. Most specifically you must never |
1223 | must not touch the values stored in it except when explicitly documented |
1141 | reinitialise it or call its C<ev_TYPE_set> macro. |
1224 | otherwise. Most specifically you must never reinitialise it or call its |
|
|
1225 | C<ev_TYPE_set> macro. |
1142 | |
1226 | |
1143 | Each and every callback receives the event loop pointer as first, the |
1227 | Each and every callback receives the event loop pointer as first, the |
1144 | registered watcher structure as second, and a bitset of received events as |
1228 | registered watcher structure as second, and a bitset of received events as |
1145 | third argument. |
1229 | third argument. |
1146 | |
1230 | |
… | |
… | |
1461 | |
1545 | |
1462 | Many event loops support I<watcher priorities>, which are usually small |
1546 | Many event loops support I<watcher priorities>, which are usually small |
1463 | integers that influence the ordering of event callback invocation |
1547 | integers that influence the ordering of event callback invocation |
1464 | between watchers in some way, all else being equal. |
1548 | between watchers in some way, all else being equal. |
1465 | |
1549 | |
1466 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
1550 | In libev, watcher priorities can be set using C<ev_set_priority>. See its |
1467 | description for the more technical details such as the actual priority |
1551 | description for the more technical details such as the actual priority |
1468 | range. |
1552 | range. |
1469 | |
1553 | |
1470 | There are two common ways how these these priorities are being interpreted |
1554 | There are two common ways how these these priorities are being interpreted |
1471 | by event loops: |
1555 | by event loops: |
… | |
… | |
1565 | |
1649 | |
1566 | This section describes each watcher in detail, but will not repeat |
1650 | This section describes each watcher in detail, but will not repeat |
1567 | information given in the last section. Any initialisation/set macros, |
1651 | information given in the last section. Any initialisation/set macros, |
1568 | functions and members specific to the watcher type are explained. |
1652 | functions and members specific to the watcher type are explained. |
1569 | |
1653 | |
1570 | Members are additionally marked with either I<[read-only]>, meaning that, |
1654 | Most members are additionally marked with either I<[read-only]>, meaning |
1571 | while the watcher is active, you can look at the member and expect some |
1655 | that, while the watcher is active, you can look at the member and expect |
1572 | sensible content, but you must not modify it (you can modify it while the |
1656 | some sensible content, but you must not modify it (you can modify it while |
1573 | watcher is stopped to your hearts content), or I<[read-write]>, which |
1657 | the watcher is stopped to your hearts content), or I<[read-write]>, which |
1574 | means you can expect it to have some sensible content while the watcher |
1658 | means you can expect it to have some sensible content while the watcher is |
1575 | is active, but you can also modify it. Modifying it may not do something |
1659 | active, but you can also modify it (within the same thread as the event |
|
|
1660 | loop, i.e. without creating data races). Modifying it may not do something |
1576 | sensible or take immediate effect (or do anything at all), but libev will |
1661 | sensible or take immediate effect (or do anything at all), but libev will |
1577 | not crash or malfunction in any way. |
1662 | not crash or malfunction in any way. |
1578 | |
1663 | |
|
|
1664 | In any case, the documentation for each member will explain what the |
|
|
1665 | effects are, and if there are any additional access restrictions. |
1579 | |
1666 | |
1580 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1667 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1581 | |
1668 | |
1582 | I/O watchers check whether a file descriptor is readable or writable |
1669 | I/O watchers check whether a file descriptor is readable or writable |
1583 | in each iteration of the event loop, or, more precisely, when reading |
1670 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1610 | |
1697 | |
1611 | But really, best use non-blocking mode. |
1698 | But really, best use non-blocking mode. |
1612 | |
1699 | |
1613 | =head3 The special problem of disappearing file descriptors |
1700 | =head3 The special problem of disappearing file descriptors |
1614 | |
1701 | |
1615 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1702 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1616 | descriptor (either due to calling C<close> explicitly or any other means, |
1703 | a file descriptor (either due to calling C<close> explicitly or any other |
1617 | such as C<dup2>). The reason is that you register interest in some file |
1704 | means, such as C<dup2>). The reason is that you register interest in some |
1618 | descriptor, but when it goes away, the operating system will silently drop |
1705 | file descriptor, but when it goes away, the operating system will silently |
1619 | this interest. If another file descriptor with the same number then is |
1706 | drop this interest. If another file descriptor with the same number then |
1620 | registered with libev, there is no efficient way to see that this is, in |
1707 | is registered with libev, there is no efficient way to see that this is, |
1621 | fact, a different file descriptor. |
1708 | in fact, a different file descriptor. |
1622 | |
1709 | |
1623 | To avoid having to explicitly tell libev about such cases, libev follows |
1710 | To avoid having to explicitly tell libev about such cases, libev follows |
1624 | the following policy: Each time C<ev_io_set> is being called, libev |
1711 | the following policy: Each time C<ev_io_set> is being called, libev |
1625 | will assume that this is potentially a new file descriptor, otherwise |
1712 | will assume that this is potentially a new file descriptor, otherwise |
1626 | it is assumed that the file descriptor stays the same. That means that |
1713 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1675 | when you rarely read from a file instead of from a socket, and want to |
1762 | when you rarely read from a file instead of from a socket, and want to |
1676 | reuse the same code path. |
1763 | reuse the same code path. |
1677 | |
1764 | |
1678 | =head3 The special problem of fork |
1765 | =head3 The special problem of fork |
1679 | |
1766 | |
1680 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1767 | Some backends (epoll, kqueue, linuxaio, iouring) do not support C<fork ()> |
1681 | useless behaviour. Libev fully supports fork, but needs to be told about |
1768 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1682 | it in the child if you want to continue to use it in the child. |
1769 | to be told about it in the child if you want to continue to use it in the |
|
|
1770 | child. |
1683 | |
1771 | |
1684 | To support fork in your child processes, you have to call C<ev_loop_fork |
1772 | To support fork in your child processes, you have to call C<ev_loop_fork |
1685 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1773 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1686 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1774 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1687 | |
1775 | |
… | |
… | |
1742 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1830 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1743 | |
1831 | |
1744 | =item ev_io_set (ev_io *, int fd, int events) |
1832 | =item ev_io_set (ev_io *, int fd, int events) |
1745 | |
1833 | |
1746 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1834 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1747 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1835 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE>, both |
1748 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1836 | C<EV_READ | EV_WRITE> or C<0>, to express the desire to receive the given |
|
|
1837 | events. |
1749 | |
1838 | |
1750 | =item int fd [read-only] |
1839 | Note that setting the C<events> to C<0> and starting the watcher is |
|
|
1840 | supported, but not specially optimized - if your program sometimes happens |
|
|
1841 | to generate this combination this is fine, but if it is easy to avoid |
|
|
1842 | starting an io watcher watching for no events you should do so. |
1751 | |
1843 | |
1752 | The file descriptor being watched. |
1844 | =item ev_io_modify (ev_io *, int events) |
1753 | |
1845 | |
|
|
1846 | Similar to C<ev_io_set>, but only changes the requested events. Using this |
|
|
1847 | might be faster with some backends, as libev can assume that the C<fd> |
|
|
1848 | still refers to the same underlying file description, something it cannot |
|
|
1849 | do when using C<ev_io_set>. |
|
|
1850 | |
|
|
1851 | =item int fd [no-modify] |
|
|
1852 | |
|
|
1853 | The file descriptor being watched. While it can be read at any time, you |
|
|
1854 | must not modify this member even when the watcher is stopped - always use |
|
|
1855 | C<ev_io_set> for that. |
|
|
1856 | |
1754 | =item int events [read-only] |
1857 | =item int events [no-modify] |
1755 | |
1858 | |
1756 | The events being watched. |
1859 | The set of events the fd is being watched for, among other flags. Remember |
|
|
1860 | that this is a bit set - to test for C<EV_READ>, use C<< w->events & |
|
|
1861 | EV_READ >>, and similarly for C<EV_WRITE>. |
|
|
1862 | |
|
|
1863 | As with C<fd>, you must not modify this member even when the watcher is |
|
|
1864 | stopped, always use C<ev_io_set> or C<ev_io_modify> for that. |
1757 | |
1865 | |
1758 | =back |
1866 | =back |
1759 | |
1867 | |
1760 | =head3 Examples |
1868 | =head3 Examples |
1761 | |
1869 | |
… | |
… | |
2225 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2333 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2226 | it, as it uses a relative timeout). |
2334 | it, as it uses a relative timeout). |
2227 | |
2335 | |
2228 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2336 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2229 | timers, such as triggering an event on each "midnight, local time", or |
2337 | timers, such as triggering an event on each "midnight, local time", or |
2230 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2338 | other complicated rules. This cannot easily be done with C<ev_timer> |
2231 | those cannot react to time jumps. |
2339 | watchers, as those cannot react to time jumps. |
2232 | |
2340 | |
2233 | As with timers, the callback is guaranteed to be invoked only when the |
2341 | As with timers, the callback is guaranteed to be invoked only when the |
2234 | point in time where it is supposed to trigger has passed. If multiple |
2342 | point in time where it is supposed to trigger has passed. If multiple |
2235 | timers become ready during the same loop iteration then the ones with |
2343 | timers become ready during the same loop iteration then the ones with |
2236 | earlier time-out values are invoked before ones with later time-out values |
2344 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2322 | |
2430 | |
2323 | NOTE: I<< This callback must always return a time that is higher than or |
2431 | NOTE: I<< This callback must always return a time that is higher than or |
2324 | equal to the passed C<now> value >>. |
2432 | equal to the passed C<now> value >>. |
2325 | |
2433 | |
2326 | This can be used to create very complex timers, such as a timer that |
2434 | This can be used to create very complex timers, such as a timer that |
2327 | triggers on "next midnight, local time". To do this, you would calculate the |
2435 | triggers on "next midnight, local time". To do this, you would calculate |
2328 | next midnight after C<now> and return the timestamp value for this. How |
2436 | the next midnight after C<now> and return the timestamp value for |
2329 | you do this is, again, up to you (but it is not trivial, which is the main |
2437 | this. Here is a (completely untested, no error checking) example on how to |
2330 | reason I omitted it as an example). |
2438 | do this: |
|
|
2439 | |
|
|
2440 | #include <time.h> |
|
|
2441 | |
|
|
2442 | static ev_tstamp |
|
|
2443 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2444 | { |
|
|
2445 | time_t tnow = (time_t)now; |
|
|
2446 | struct tm tm; |
|
|
2447 | localtime_r (&tnow, &tm); |
|
|
2448 | |
|
|
2449 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2450 | ++tm.tm_mday; // midnight next day |
|
|
2451 | |
|
|
2452 | return mktime (&tm); |
|
|
2453 | } |
|
|
2454 | |
|
|
2455 | Note: this code might run into trouble on days that have more then two |
|
|
2456 | midnights (beginning and end). |
2331 | |
2457 | |
2332 | =back |
2458 | =back |
2333 | |
2459 | |
2334 | =item ev_periodic_again (loop, ev_periodic *) |
2460 | =item ev_periodic_again (loop, ev_periodic *) |
2335 | |
2461 | |
… | |
… | |
3960 | The normal C API should work fine when used from C++: both ev.h and the |
4086 | The normal C API should work fine when used from C++: both ev.h and the |
3961 | libev sources can be compiled as C++. Therefore, code that uses the C API |
4087 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3962 | will work fine. |
4088 | will work fine. |
3963 | |
4089 | |
3964 | Proper exception specifications might have to be added to callbacks passed |
4090 | Proper exception specifications might have to be added to callbacks passed |
3965 | to libev: exceptions may be thrown only from watcher callbacks, all |
4091 | to libev: exceptions may be thrown only from watcher callbacks, all other |
3966 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4092 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
3967 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
4093 | callbacks) must not throw exceptions, and might need a C<noexcept> |
3968 | ()> specification. If you have code that needs to be compiled as both C |
4094 | specification. If you have code that needs to be compiled as both C and |
3969 | and C++ you can use the C<EV_THROW> macro for this: |
4095 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
3970 | |
4096 | |
3971 | static void |
4097 | static void |
3972 | fatal_error (const char *msg) EV_THROW |
4098 | fatal_error (const char *msg) EV_NOEXCEPT |
3973 | { |
4099 | { |
3974 | perror (msg); |
4100 | perror (msg); |
3975 | abort (); |
4101 | abort (); |
3976 | } |
4102 | } |
3977 | |
4103 | |
… | |
… | |
4141 | method. |
4267 | method. |
4142 | |
4268 | |
4143 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
4269 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
4144 | clashing with the C<set (loop)> method. |
4270 | clashing with the C<set (loop)> method. |
4145 | |
4271 | |
|
|
4272 | For C<ev::io> watchers there is an additional C<set> method that acepts a |
|
|
4273 | new event mask only, and internally calls C<ev_io_modfify>. |
|
|
4274 | |
4146 | =item w->start () |
4275 | =item w->start () |
4147 | |
4276 | |
4148 | Starts the watcher. Note that there is no C<loop> argument, as the |
4277 | Starts the watcher. Note that there is no C<loop> argument, as the |
4149 | constructor already stores the event loop. |
4278 | constructor already stores the event loop. |
4150 | |
4279 | |
… | |
… | |
4390 | ev_win32.c required on win32 platforms only |
4519 | ev_win32.c required on win32 platforms only |
4391 | |
4520 | |
4392 | ev_select.c only when select backend is enabled |
4521 | ev_select.c only when select backend is enabled |
4393 | ev_poll.c only when poll backend is enabled |
4522 | ev_poll.c only when poll backend is enabled |
4394 | ev_epoll.c only when the epoll backend is enabled |
4523 | ev_epoll.c only when the epoll backend is enabled |
|
|
4524 | ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4525 | ev_iouring.c only when the linux io_uring backend is enabled |
4395 | ev_kqueue.c only when the kqueue backend is enabled |
4526 | ev_kqueue.c only when the kqueue backend is enabled |
4396 | ev_port.c only when the solaris port backend is enabled |
4527 | ev_port.c only when the solaris port backend is enabled |
4397 | |
4528 | |
4398 | F<ev.c> includes the backend files directly when enabled, so you only need |
4529 | F<ev.c> includes the backend files directly when enabled, so you only need |
4399 | to compile this single file. |
4530 | to compile this single file. |
… | |
… | |
4520 | available and will probe for kernel support at runtime. This will improve |
4651 | available and will probe for kernel support at runtime. This will improve |
4521 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
4652 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
4522 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
4653 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
4523 | 2.7 or newer, otherwise disabled. |
4654 | 2.7 or newer, otherwise disabled. |
4524 | |
4655 | |
|
|
4656 | =item EV_USE_SIGNALFD |
|
|
4657 | |
|
|
4658 | If defined to be C<1>, then libev will assume that C<signalfd ()> is |
|
|
4659 | available and will probe for kernel support at runtime. This enables |
|
|
4660 | the use of EVFLAG_SIGNALFD for faster and simpler signal handling. If |
|
|
4661 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4662 | 2.7 or newer, otherwise disabled. |
|
|
4663 | |
|
|
4664 | =item EV_USE_TIMERFD |
|
|
4665 | |
|
|
4666 | If defined to be C<1>, then libev will assume that C<timerfd ()> is |
|
|
4667 | available and will probe for kernel support at runtime. This allows |
|
|
4668 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4669 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4670 | C<TFD_TIMER_CANCEL_ON_SET>, otherwise disabled. |
|
|
4671 | |
|
|
4672 | =item EV_USE_EVENTFD |
|
|
4673 | |
|
|
4674 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
4675 | available and will probe for kernel support at runtime. This will improve |
|
|
4676 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
4677 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4678 | 2.7 or newer, otherwise disabled. |
|
|
4679 | |
4525 | =item EV_USE_SELECT |
4680 | =item EV_USE_SELECT |
4526 | |
4681 | |
4527 | If undefined or defined to be C<1>, libev will compile in support for the |
4682 | If undefined or defined to be C<1>, libev will compile in support for the |
4528 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
4683 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
4529 | other method takes over, select will be it. Otherwise the select backend |
4684 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
4589 | If defined to be C<1>, libev will compile in support for the Linux |
4744 | If defined to be C<1>, libev will compile in support for the Linux |
4590 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4745 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4591 | otherwise another method will be used as fallback. This is the preferred |
4746 | otherwise another method will be used as fallback. This is the preferred |
4592 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4747 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4593 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4748 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4749 | |
|
|
4750 | =item EV_USE_LINUXAIO |
|
|
4751 | |
|
|
4752 | If defined to be C<1>, libev will compile in support for the Linux aio |
|
|
4753 | backend (C<EV_USE_EPOLL> must also be enabled). If undefined, it will be |
|
|
4754 | enabled on linux, otherwise disabled. |
|
|
4755 | |
|
|
4756 | =item EV_USE_IOURING |
|
|
4757 | |
|
|
4758 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4759 | io_uring backend (C<EV_USE_EPOLL> must also be enabled). Due to it's |
|
|
4760 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4761 | will be enabled on linux, otherwise disabled. |
4594 | |
4762 | |
4595 | =item EV_USE_KQUEUE |
4763 | =item EV_USE_KQUEUE |
4596 | |
4764 | |
4597 | If defined to be C<1>, libev will compile in support for the BSD style |
4765 | If defined to be C<1>, libev will compile in support for the BSD style |
4598 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4766 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
4876 | called. If set to C<2>, then the internal verification code will be |
5044 | called. If set to C<2>, then the internal verification code will be |
4877 | called once per loop, which can slow down libev. If set to C<3>, then the |
5045 | called once per loop, which can slow down libev. If set to C<3>, then the |
4878 | verification code will be called very frequently, which will slow down |
5046 | verification code will be called very frequently, which will slow down |
4879 | libev considerably. |
5047 | libev considerably. |
4880 | |
5048 | |
|
|
5049 | Verification errors are reported via C's C<assert> mechanism, so if you |
|
|
5050 | disable that (e.g. by defining C<NDEBUG>) then no errors will be reported. |
|
|
5051 | |
4881 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
5052 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4882 | will be C<0>. |
5053 | will be C<0>. |
4883 | |
5054 | |
4884 | =item EV_COMMON |
5055 | =item EV_COMMON |
4885 | |
5056 | |