… | |
… | |
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 |
… | |
… | |
476 | unblocking the signals. |
480 | unblocking the signals. |
477 | |
481 | |
478 | 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 |
479 | C<sigprocmask>, whose behaviour is officially unspecified. |
483 | C<sigprocmask>, whose behaviour is officially unspecified. |
480 | |
484 | |
481 | 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. |
482 | |
495 | |
483 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
496 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
484 | |
497 | |
485 | 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 |
486 | 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, |
… | |
… | |
511 | 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 |
512 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
525 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
513 | |
526 | |
514 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
527 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
515 | |
528 | |
516 | 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 |
517 | kernels). |
530 | kernels). |
518 | |
531 | |
519 | 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 |
520 | it scales phenomenally better. While poll and select usually scale like |
533 | it scales phenomenally better. While poll and select usually scale like |
521 | 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 |
… | |
… | |
567 | 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 |
568 | 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 |
569 | the usage. So sad. |
582 | the usage. So sad. |
570 | |
583 | |
571 | 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 |
572 | all kernel versions tested so far. |
585 | a lot of kernel revisions, but probably(!) works in current versions. |
573 | |
586 | |
574 | 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 |
575 | C<EVBACKEND_POLL>. |
588 | C<EVBACKEND_POLL>. |
576 | |
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 | |
577 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
634 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
578 | |
635 | |
579 | Kqueue deserves special mention, as at the time of this writing, it |
636 | Kqueue deserves special mention, as at the time this backend was |
580 | 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 |
581 | with anything but sockets and pipes, except on Darwin, where of course |
638 | work reliably with anything but sockets and pipes, except on Darwin, |
582 | it's completely useless). Unlike epoll, however, whose brokenness |
639 | where of course it's completely useless). Unlike epoll, however, whose |
583 | 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) |
584 | 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 |
585 | "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 |
586 | 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 |
587 | system like NetBSD. |
644 | known-to-be-good (-enough) system like NetBSD. |
588 | |
645 | |
589 | 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 |
590 | 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 |
591 | the target platform). See C<ev_embed> watchers for more info. |
648 | the target platform). See C<ev_embed> watchers for more info. |
592 | |
649 | |
593 | 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 |
594 | 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 |
595 | 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 |
596 | 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 |
597 | 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 |
598 | 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 |
599 | drops fds silently in similarly hard-to-detect cases. |
656 | drops fds silently in similarly hard-to-detect cases. |
600 | |
657 | |
601 | This backend usually performs well under most conditions. |
658 | This backend usually performs well under most conditions. |
602 | |
659 | |
603 | While nominally embeddable in other event loops, this doesn't work |
660 | While nominally embeddable in other event loops, this doesn't work |
… | |
… | |
677 | |
734 | |
678 | 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 |
679 | used if available. |
736 | used if available. |
680 | |
737 | |
681 | 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); |
682 | |
745 | |
683 | =item ev_loop_destroy (loop) |
746 | =item ev_loop_destroy (loop) |
684 | |
747 | |
685 | Destroys an event loop object (frees all memory and kernel state |
748 | Destroys an event loop object (frees all memory and kernel state |
686 | 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 |
… | |
… | |
1481 | |
1544 | |
1482 | Many event loops support I<watcher priorities>, which are usually small |
1545 | Many event loops support I<watcher priorities>, which are usually small |
1483 | integers that influence the ordering of event callback invocation |
1546 | integers that influence the ordering of event callback invocation |
1484 | between watchers in some way, all else being equal. |
1547 | between watchers in some way, all else being equal. |
1485 | |
1548 | |
1486 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
1549 | In libev, watcher priorities can be set using C<ev_set_priority>. See its |
1487 | description for the more technical details such as the actual priority |
1550 | description for the more technical details such as the actual priority |
1488 | range. |
1551 | range. |
1489 | |
1552 | |
1490 | There are two common ways how these these priorities are being interpreted |
1553 | There are two common ways how these these priorities are being interpreted |
1491 | by event loops: |
1554 | by event loops: |
… | |
… | |
1585 | |
1648 | |
1586 | This section describes each watcher in detail, but will not repeat |
1649 | This section describes each watcher in detail, but will not repeat |
1587 | information given in the last section. Any initialisation/set macros, |
1650 | information given in the last section. Any initialisation/set macros, |
1588 | functions and members specific to the watcher type are explained. |
1651 | functions and members specific to the watcher type are explained. |
1589 | |
1652 | |
1590 | Members are additionally marked with either I<[read-only]>, meaning that, |
1653 | Most members are additionally marked with either I<[read-only]>, meaning |
1591 | while the watcher is active, you can look at the member and expect some |
1654 | that, while the watcher is active, you can look at the member and expect |
1592 | sensible content, but you must not modify it (you can modify it while the |
1655 | some sensible content, but you must not modify it (you can modify it while |
1593 | watcher is stopped to your hearts content), or I<[read-write]>, which |
1656 | the watcher is stopped to your hearts content), or I<[read-write]>, which |
1594 | means you can expect it to have some sensible content while the watcher |
1657 | means you can expect it to have some sensible content while the watcher |
1595 | is active, but you can also modify it. Modifying it may not do something |
1658 | is active, but you can also modify it. Modifying it may not do something |
1596 | sensible or take immediate effect (or do anything at all), but libev will |
1659 | sensible or take immediate effect (or do anything at all), but libev will |
1597 | not crash or malfunction in any way. |
1660 | not crash or malfunction in any way. |
1598 | |
1661 | |
|
|
1662 | In any case, the documentation for each member will explain what the |
|
|
1663 | effects are, and if there are any additional access restrictions. |
1599 | |
1664 | |
1600 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1665 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1601 | |
1666 | |
1602 | I/O watchers check whether a file descriptor is readable or writable |
1667 | I/O watchers check whether a file descriptor is readable or writable |
1603 | in each iteration of the event loop, or, more precisely, when reading |
1668 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1630 | |
1695 | |
1631 | But really, best use non-blocking mode. |
1696 | But really, best use non-blocking mode. |
1632 | |
1697 | |
1633 | =head3 The special problem of disappearing file descriptors |
1698 | =head3 The special problem of disappearing file descriptors |
1634 | |
1699 | |
1635 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1700 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1636 | descriptor (either due to calling C<close> explicitly or any other means, |
1701 | a file descriptor (either due to calling C<close> explicitly or any other |
1637 | such as C<dup2>). The reason is that you register interest in some file |
1702 | means, such as C<dup2>). The reason is that you register interest in some |
1638 | descriptor, but when it goes away, the operating system will silently drop |
1703 | file descriptor, but when it goes away, the operating system will silently |
1639 | this interest. If another file descriptor with the same number then is |
1704 | drop this interest. If another file descriptor with the same number then |
1640 | registered with libev, there is no efficient way to see that this is, in |
1705 | is registered with libev, there is no efficient way to see that this is, |
1641 | fact, a different file descriptor. |
1706 | in fact, a different file descriptor. |
1642 | |
1707 | |
1643 | To avoid having to explicitly tell libev about such cases, libev follows |
1708 | To avoid having to explicitly tell libev about such cases, libev follows |
1644 | the following policy: Each time C<ev_io_set> is being called, libev |
1709 | the following policy: Each time C<ev_io_set> is being called, libev |
1645 | will assume that this is potentially a new file descriptor, otherwise |
1710 | will assume that this is potentially a new file descriptor, otherwise |
1646 | it is assumed that the file descriptor stays the same. That means that |
1711 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1695 | when you rarely read from a file instead of from a socket, and want to |
1760 | when you rarely read from a file instead of from a socket, and want to |
1696 | reuse the same code path. |
1761 | reuse the same code path. |
1697 | |
1762 | |
1698 | =head3 The special problem of fork |
1763 | =head3 The special problem of fork |
1699 | |
1764 | |
1700 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1765 | Some backends (epoll, kqueue, linuxaio, iouring) do not support C<fork ()> |
1701 | useless behaviour. Libev fully supports fork, but needs to be told about |
1766 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1702 | it in the child if you want to continue to use it in the child. |
1767 | to be told about it in the child if you want to continue to use it in the |
|
|
1768 | child. |
1703 | |
1769 | |
1704 | To support fork in your child processes, you have to call C<ev_loop_fork |
1770 | To support fork in your child processes, you have to call C<ev_loop_fork |
1705 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1771 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1706 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1772 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1707 | |
1773 | |
… | |
… | |
1765 | |
1831 | |
1766 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1832 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1767 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1833 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1768 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1834 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1769 | |
1835 | |
1770 | =item int fd [read-only] |
1836 | =item ev_io_modify (ev_io *, int events) |
1771 | |
1837 | |
1772 | The file descriptor being watched. |
1838 | Similar to C<ev_io_set>, but only changes the event mask. Using this might |
|
|
1839 | be faster with some backends, as libev can assume that the C<fd> still |
|
|
1840 | refers to the same underlying file description, something it cannot do |
|
|
1841 | when using C<ev_io_set>. |
1773 | |
1842 | |
|
|
1843 | =item int fd [no-modify] |
|
|
1844 | |
|
|
1845 | The file descriptor being watched. While it can be read at any time, you |
|
|
1846 | must not modify this member even when the watcher is stopped - always use |
|
|
1847 | C<ev_io_set> for that. |
|
|
1848 | |
1774 | =item int events [read-only] |
1849 | =item int events [no-modify] |
1775 | |
1850 | |
1776 | The events being watched. |
1851 | The set of events being watched, among other flags. This field is a |
|
|
1852 | bit set - to test for C<EV_READ>, use C<< w->events & EV_READ >>, and |
|
|
1853 | similarly for C<EV_WRITE>. |
|
|
1854 | |
|
|
1855 | As with C<fd>, you must not modify this member even when the watcher is |
|
|
1856 | stopped, always use C<ev_io_set> or C<ev_io_modify> for that. |
1777 | |
1857 | |
1778 | =back |
1858 | =back |
1779 | |
1859 | |
1780 | =head3 Examples |
1860 | =head3 Examples |
1781 | |
1861 | |
… | |
… | |
4428 | ev_win32.c required on win32 platforms only |
4508 | ev_win32.c required on win32 platforms only |
4429 | |
4509 | |
4430 | ev_select.c only when select backend is enabled |
4510 | ev_select.c only when select backend is enabled |
4431 | ev_poll.c only when poll backend is enabled |
4511 | ev_poll.c only when poll backend is enabled |
4432 | ev_epoll.c only when the epoll backend is enabled |
4512 | ev_epoll.c only when the epoll backend is enabled |
|
|
4513 | ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4514 | ev_iouring.c only when the linux io_uring backend is enabled |
4433 | ev_kqueue.c only when the kqueue backend is enabled |
4515 | ev_kqueue.c only when the kqueue backend is enabled |
4434 | ev_port.c only when the solaris port backend is enabled |
4516 | ev_port.c only when the solaris port backend is enabled |
4435 | |
4517 | |
4436 | F<ev.c> includes the backend files directly when enabled, so you only need |
4518 | F<ev.c> includes the backend files directly when enabled, so you only need |
4437 | to compile this single file. |
4519 | to compile this single file. |
… | |
… | |
4558 | available and will probe for kernel support at runtime. This will improve |
4640 | available and will probe for kernel support at runtime. This will improve |
4559 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
4641 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
4560 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
4642 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
4561 | 2.7 or newer, otherwise disabled. |
4643 | 2.7 or newer, otherwise disabled. |
4562 | |
4644 | |
|
|
4645 | =item EV_USE_SIGNALFD |
|
|
4646 | |
|
|
4647 | If defined to be C<1>, then libev will assume that C<signalfd ()> is |
|
|
4648 | available and will probe for kernel support at runtime. This enables |
|
|
4649 | the use of EVFLAG_SIGNALFD for faster and simpler signal handling. If |
|
|
4650 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4651 | 2.7 or newer, otherwise disabled. |
|
|
4652 | |
|
|
4653 | =item EV_USE_TIMERFD |
|
|
4654 | |
|
|
4655 | If defined to be C<1>, then libev will assume that C<timerfd ()> is |
|
|
4656 | available and will probe for kernel support at runtime. This allows |
|
|
4657 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4658 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4659 | C<TFD_TIMER_CANCEL_ON_SET>, otherwise disabled. |
|
|
4660 | |
|
|
4661 | =item EV_USE_EVENTFD |
|
|
4662 | |
|
|
4663 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
4664 | available and will probe for kernel support at runtime. This will improve |
|
|
4665 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
4666 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4667 | 2.7 or newer, otherwise disabled. |
|
|
4668 | |
4563 | =item EV_USE_SELECT |
4669 | =item EV_USE_SELECT |
4564 | |
4670 | |
4565 | If undefined or defined to be C<1>, libev will compile in support for the |
4671 | If undefined or defined to be C<1>, libev will compile in support for the |
4566 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
4672 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
4567 | other method takes over, select will be it. Otherwise the select backend |
4673 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
4627 | If defined to be C<1>, libev will compile in support for the Linux |
4733 | If defined to be C<1>, libev will compile in support for the Linux |
4628 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4734 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4629 | otherwise another method will be used as fallback. This is the preferred |
4735 | otherwise another method will be used as fallback. This is the preferred |
4630 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4736 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4631 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4737 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4738 | |
|
|
4739 | =item EV_USE_LINUXAIO |
|
|
4740 | |
|
|
4741 | If defined to be C<1>, libev will compile in support for the Linux aio |
|
|
4742 | backend (C<EV_USE_EPOLL> must also be enabled). If undefined, it will be |
|
|
4743 | enabled on linux, otherwise disabled. |
|
|
4744 | |
|
|
4745 | =item EV_USE_IOURING |
|
|
4746 | |
|
|
4747 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4748 | io_uring backend (C<EV_USE_EPOLL> must also be enabled). Due to it's |
|
|
4749 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4750 | will be enabled on linux, otherwise disabled. |
4632 | |
4751 | |
4633 | =item EV_USE_KQUEUE |
4752 | =item EV_USE_KQUEUE |
4634 | |
4753 | |
4635 | If defined to be C<1>, libev will compile in support for the BSD style |
4754 | If defined to be C<1>, libev will compile in support for the BSD style |
4636 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4755 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
4914 | called. If set to C<2>, then the internal verification code will be |
5033 | called. If set to C<2>, then the internal verification code will be |
4915 | called once per loop, which can slow down libev. If set to C<3>, then the |
5034 | called once per loop, which can slow down libev. If set to C<3>, then the |
4916 | verification code will be called very frequently, which will slow down |
5035 | verification code will be called very frequently, which will slow down |
4917 | libev considerably. |
5036 | libev considerably. |
4918 | |
5037 | |
|
|
5038 | Verification errors are reported via C's C<assert> mechanism, so if you |
|
|
5039 | disable that (e.g. by defining C<NDEBUG>) then no errors will be reported. |
|
|
5040 | |
4919 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
5041 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4920 | will be C<0>. |
5042 | will be C<0>. |
4921 | |
5043 | |
4922 | =item EV_COMMON |
5044 | =item EV_COMMON |
4923 | |
5045 | |