… | |
… | |
131 | .\} |
131 | .\} |
132 | .rm #[ #] #H #V #F C |
132 | .rm #[ #] #H #V #F C |
133 | .\" ======================================================================== |
133 | .\" ======================================================================== |
134 | .\" |
134 | .\" |
135 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
136 | .TH LIBEV 3 "2019-06-23" "libev-4.25" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2021-01-11" "libev-4.33" "libev - high performance full featured event loop" |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
138 | .\" way too many mistakes in technical documents. |
138 | .\" way too many mistakes in technical documents. |
139 | .if n .ad l |
139 | .if n .ad l |
140 | .nh |
140 | .nh |
141 | .SH "NAME" |
141 | .SH "NAME" |
… | |
… | |
291 | When libev detects a usage error such as a negative timer interval, then |
291 | When libev detects a usage error such as a negative timer interval, then |
292 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
292 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
293 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
293 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
294 | the libev caller and need to be fixed there. |
294 | the libev caller and need to be fixed there. |
295 | .PP |
295 | .PP |
|
|
296 | Via the \f(CW\*(C`EV_FREQUENT\*(C'\fR macro you can compile in and/or enable extensive |
|
|
297 | consistency checking code inside libev that can be used to check for |
|
|
298 | internal inconsistencies, suually caused by application bugs. |
|
|
299 | .PP |
296 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
300 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions. These do not |
297 | extensive consistency checking code. These do not trigger under normal |
|
|
298 | circumstances, as they indicate either a bug in libev or worse. |
301 | trigger under normal circumstances, as they indicate either a bug in libev |
|
|
302 | or worse. |
299 | .SH "GLOBAL FUNCTIONS" |
303 | .SH "GLOBAL FUNCTIONS" |
300 | .IX Header "GLOBAL FUNCTIONS" |
304 | .IX Header "GLOBAL FUNCTIONS" |
301 | These functions can be called anytime, even before initialising the |
305 | These functions can be called anytime, even before initialising the |
302 | library in any way. |
306 | library in any way. |
303 | .IP "ev_tstamp ev_time ()" 4 |
307 | .IP "ev_tstamp ev_time ()" 4 |
… | |
… | |
602 | want to handle signals only in specific threads and want to avoid libev |
606 | want to handle signals only in specific threads and want to avoid libev |
603 | unblocking the signals. |
607 | unblocking the signals. |
604 | .Sp |
608 | .Sp |
605 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
609 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
606 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
610 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
611 | .ie n .IP """EVFLAG_NOTIMERFD""" 4 |
|
|
612 | .el .IP "\f(CWEVFLAG_NOTIMERFD\fR" 4 |
|
|
613 | .IX Item "EVFLAG_NOTIMERFD" |
|
|
614 | When this flag is specified, the libev will avoid using a \f(CW\*(C`timerfd\*(C'\fR to |
|
|
615 | detect time jumps. It will still be able to detect time jumps, but takes |
|
|
616 | longer and has a lower accuracy in doing so, but saves a file descriptor |
|
|
617 | per loop. |
607 | .Sp |
618 | .Sp |
608 | This flag's behaviour will become the default in future versions of libev. |
619 | The current implementation only tries to use a \f(CW\*(C`timerfd\*(C'\fR when the first |
|
|
620 | \&\f(CW\*(C`ev_periodic\*(C'\fR watcher is started and falls back on other methods if it |
|
|
621 | cannot be created, but this behaviour might change in the future. |
609 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
622 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
610 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
623 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
611 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
624 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
612 | This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
625 | This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
613 | libev tries to roll its own fd_set with no limits on the number of fds, |
626 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
638 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
651 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
639 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
652 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
640 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
653 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
641 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
654 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
642 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
655 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
643 | Use the linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
656 | Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
644 | kernels). |
657 | kernels). |
645 | .Sp |
658 | .Sp |
646 | For few fds, this backend is a bit little slower than poll and select, but |
659 | For few fds, this backend is a bit little slower than poll and select, but |
647 | it scales phenomenally better. While poll and select usually scale like |
660 | it scales phenomenally better. While poll and select usually scale like |
648 | O(total_fds) where total_fds is the total number of fds (or the highest |
661 | O(total_fds) where total_fds is the total number of fds (or the highest |
… | |
… | |
701 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
714 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
702 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
715 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
703 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
716 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
704 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
717 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
705 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
718 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
706 | Use the linux-specific linux aio (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels. |
719 | Use the Linux-specific Linux \s-1AIO\s0 (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels (but libev |
|
|
720 | only tries to use it in 4.19+). |
|
|
721 | .Sp |
|
|
722 | This is another Linux train wreck of an event interface. |
707 | .Sp |
723 | .Sp |
708 | If this backend works for you (as of this writing, it was very |
724 | If this backend works for you (as of this writing, it was very |
709 | experimental), it is the best event interface available on linux and might |
725 | experimental), it is the best event interface available on Linux and might |
710 | be well worth enabling it \- if it isn't available in your kernel this will |
726 | be well worth enabling it \- if it isn't available in your kernel this will |
711 | be detected and this backend will be skipped. |
727 | be detected and this backend will be skipped. |
712 | .Sp |
728 | .Sp |
713 | This backend can batch oneshot requests and supports a user-space ring |
729 | This backend can batch oneshot requests and supports a user-space ring |
714 | buffer to receive events. It also doesn't suffer from most of the design |
730 | buffer to receive events. It also doesn't suffer from most of the design |
715 | problems of epoll (such as not being able to remove event sources from |
731 | problems of epoll (such as not being able to remove event sources from |
716 | the epoll set), and generally sounds too good to be true. Because, this |
732 | the epoll set), and generally sounds too good to be true. Because, this |
717 | being the linux kernel, of course it suffers from a whole new set of |
733 | being the Linux kernel, of course it suffers from a whole new set of |
718 | limitations. |
734 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
735 | issues. |
719 | .Sp |
736 | .Sp |
720 | For one, it is not easily embeddable (but probably could be done using |
737 | For one, it is not easily embeddable (but probably could be done using |
721 | an event fd at some extra overhead). It also is subject to a system wide |
738 | an event fd at some extra overhead). It also is subject to a system wide |
722 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR \- each loop |
739 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
723 | currently requires \f(CW61\fR of this number. If no aio requests are left, this |
|
|
724 | backend will be skipped during initialisation. |
740 | requests are left, this backend will be skipped during initialisation, and |
|
|
741 | will switch to epoll when the loop is active. |
725 | .Sp |
742 | .Sp |
726 | Most problematic in practise, however, is that not all file descriptors |
743 | Most problematic in practice, however, is that not all file descriptors |
727 | work with it. For example, in linux 5.1, tcp sockets, pipes, event fds, |
744 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
728 | files, \fI/dev/null\fR and a few others are supported, but ttys do not work |
745 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
729 | (probably because of a bug), so this is not (yet?) a generic event polling |
746 | properly (a known bug that the kernel developers don't care about, see |
730 | interface. |
747 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
748 | (yet?) a generic event polling interface. |
731 | .Sp |
749 | .Sp |
|
|
750 | Overall, it seems the Linux developers just don't want it to have a |
|
|
751 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
|
|
752 | .Sp |
732 | To work around this latter problem, the current version of libev uses |
753 | To work around all these problem, the current version of libev uses its |
733 | epoll as a fallback for file deescriptor types that do not work. Epoll |
754 | epoll backend as a fallback for file descriptor types that do not work. Or |
734 | is used in, kind of, slow mode that hopefully avoids most of its design |
755 | falls back completely to epoll if the kernel acts up. |
735 | problems and requires 1\-3 extra syscalls per active fd every iteration. |
|
|
736 | .Sp |
756 | .Sp |
737 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
757 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
738 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
758 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
739 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
759 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
740 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
760 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
741 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
761 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
742 | Kqueue deserves special mention, as at the time of this writing, it |
762 | Kqueue deserves special mention, as at the time this backend was |
743 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
763 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
744 | with anything but sockets and pipes, except on Darwin, where of course |
764 | work reliably with anything but sockets and pipes, except on Darwin, |
745 | it's completely useless). Unlike epoll, however, whose brokenness |
765 | where of course it's completely useless). Unlike epoll, however, whose |
746 | is by design, these kqueue bugs can (and eventually will) be fixed |
766 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
747 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
767 | fixed without \s-1API\s0 changes to existing programs. For this reason it's not |
748 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
768 | being \*(L"auto-detected\*(R" on all platforms unless you explicitly specify it |
749 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
769 | in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a |
750 | system like NetBSD. |
770 | known-to-be-good (\-enough) system like NetBSD. |
751 | .Sp |
771 | .Sp |
752 | You still can embed kqueue into a normal poll or select backend and use it |
772 | You still can embed kqueue into a normal poll or select backend and use it |
753 | only for sockets (after having made sure that sockets work with kqueue on |
773 | only for sockets (after having made sure that sockets work with kqueue on |
754 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
774 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
755 | .Sp |
775 | .Sp |
756 | It scales in the same way as the epoll backend, but the interface to the |
776 | It scales in the same way as the epoll backend, but the interface to the |
757 | kernel is more efficient (which says nothing about its actual speed, of |
777 | kernel is more efficient (which says nothing about its actual speed, of |
758 | course). While stopping, setting and starting an I/O watcher does never |
778 | course). While stopping, setting and starting an I/O watcher does never |
759 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
779 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
760 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
780 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
761 | might have to leak fd's on fork, but it's more sane than epoll) and it |
781 | might have to leak fds on fork, but it's more sane than epoll) and it |
762 | drops fds silently in similarly hard-to-detect cases. |
782 | drops fds silently in similarly hard-to-detect cases. |
763 | .Sp |
783 | .Sp |
764 | This backend usually performs well under most conditions. |
784 | This backend usually performs well under most conditions. |
765 | .Sp |
785 | .Sp |
766 | While nominally embeddable in other event loops, this doesn't work |
786 | While nominally embeddable in other event loops, this doesn't work |
… | |
… | |
1067 | \& \- Queue all expired timers. |
1087 | \& \- Queue all expired timers. |
1068 | \& \- Queue all expired periodics. |
1088 | \& \- Queue all expired periodics. |
1069 | \& \- Queue all idle watchers with priority higher than that of pending events. |
1089 | \& \- Queue all idle watchers with priority higher than that of pending events. |
1070 | \& \- Queue all check watchers. |
1090 | \& \- Queue all check watchers. |
1071 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1091 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1072 | \& Signals and child watchers are implemented as I/O watchers, and will |
1092 | \& Signals, async and child watchers are implemented as I/O watchers, and |
1073 | \& be handled here by queueing them when their watcher gets executed. |
1093 | \& will be handled here by queueing them when their watcher gets executed. |
1074 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
1094 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
1075 | \& were used, or there are no active watchers, goto FINISH, otherwise |
1095 | \& were used, or there are no active watchers, goto FINISH, otherwise |
1076 | \& continue with step LOOP. |
1096 | \& continue with step LOOP. |
1077 | \& FINISH: |
1097 | \& FINISH: |
1078 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
1098 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
… | |
… | |
1329 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1349 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1330 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1350 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1331 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1351 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1332 | .PP |
1352 | .PP |
1333 | As long as your watcher is active (has been started but not stopped) you |
1353 | As long as your watcher is active (has been started but not stopped) you |
1334 | must not touch the values stored in it. Most specifically you must never |
1354 | must not touch the values stored in it except when explicitly documented |
1335 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1355 | otherwise. Most specifically you must never reinitialise it or call its |
|
|
1356 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1336 | .PP |
1357 | .PP |
1337 | Each and every callback receives the event loop pointer as first, the |
1358 | Each and every callback receives the event loop pointer as first, the |
1338 | registered watcher structure as second, and a bitset of received events as |
1359 | registered watcher structure as second, and a bitset of received events as |
1339 | third argument. |
1360 | third argument. |
1340 | .PP |
1361 | .PP |
… | |
… | |
1511 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1532 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1512 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1533 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1513 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1534 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1514 | Returns a true value iff the watcher is active (i.e. it has been started |
1535 | Returns a true value iff the watcher is active (i.e. it has been started |
1515 | and not yet been stopped). As long as a watcher is active you must not modify |
1536 | and not yet been stopped). As long as a watcher is active you must not modify |
1516 | it. |
1537 | it unless documented otherwise. |
1517 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1538 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1518 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1539 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1519 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1540 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1520 | events but its callback has not yet been invoked). As long as a watcher |
1541 | events but its callback has not yet been invoked). As long as a watcher |
1521 | is pending (but not active) you must not call an init function on it (but |
1542 | is pending (but not active) you must not call an init function on it (but |
… | |
… | |
1643 | .IX Subsection "WATCHER PRIORITY MODELS" |
1664 | .IX Subsection "WATCHER PRIORITY MODELS" |
1644 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1665 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1645 | integers that influence the ordering of event callback invocation |
1666 | integers that influence the ordering of event callback invocation |
1646 | between watchers in some way, all else being equal. |
1667 | between watchers in some way, all else being equal. |
1647 | .PP |
1668 | .PP |
1648 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1669 | In libev, watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1649 | description for the more technical details such as the actual priority |
1670 | description for the more technical details such as the actual priority |
1650 | range. |
1671 | range. |
1651 | .PP |
1672 | .PP |
1652 | There are two common ways how these these priorities are being interpreted |
1673 | There are two common ways how these these priorities are being interpreted |
1653 | by event loops: |
1674 | by event loops: |
… | |
… | |
1747 | .IX Header "WATCHER TYPES" |
1768 | .IX Header "WATCHER TYPES" |
1748 | This section describes each watcher in detail, but will not repeat |
1769 | This section describes each watcher in detail, but will not repeat |
1749 | information given in the last section. Any initialisation/set macros, |
1770 | information given in the last section. Any initialisation/set macros, |
1750 | functions and members specific to the watcher type are explained. |
1771 | functions and members specific to the watcher type are explained. |
1751 | .PP |
1772 | .PP |
1752 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
1773 | Most members are additionally marked with either \fI[read\-only]\fR, meaning |
1753 | while the watcher is active, you can look at the member and expect some |
1774 | that, while the watcher is active, you can look at the member and expect |
1754 | sensible content, but you must not modify it (you can modify it while the |
1775 | some sensible content, but you must not modify it (you can modify it while |
1755 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1776 | the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1756 | means you can expect it to have some sensible content while the watcher |
1777 | means you can expect it to have some sensible content while the watcher is |
1757 | is active, but you can also modify it. Modifying it may not do something |
1778 | active, but you can also modify it (within the same thread as the event |
|
|
1779 | loop, i.e. without creating data races). Modifying it may not do something |
1758 | sensible or take immediate effect (or do anything at all), but libev will |
1780 | sensible or take immediate effect (or do anything at all), but libev will |
1759 | not crash or malfunction in any way. |
1781 | not crash or malfunction in any way. |
|
|
1782 | .PP |
|
|
1783 | In any case, the documentation for each member will explain what the |
|
|
1784 | effects are, and if there are any additional access restrictions. |
1760 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1785 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1761 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1786 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1762 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1787 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1763 | I/O watchers check whether a file descriptor is readable or writable |
1788 | I/O watchers check whether a file descriptor is readable or writable |
1764 | in each iteration of the event loop, or, more precisely, when reading |
1789 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1860 | reuse the same code path. |
1885 | reuse the same code path. |
1861 | .PP |
1886 | .PP |
1862 | \fIThe special problem of fork\fR |
1887 | \fIThe special problem of fork\fR |
1863 | .IX Subsection "The special problem of fork" |
1888 | .IX Subsection "The special problem of fork" |
1864 | .PP |
1889 | .PP |
1865 | Some backends (epoll, kqueue, probably linuxaio) do not support \f(CW\*(C`fork ()\*(C'\fR |
1890 | Some backends (epoll, kqueue, linuxaio, iouring) do not support \f(CW\*(C`fork ()\*(C'\fR |
1866 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1891 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1867 | to be told about it in the child if you want to continue to use it in the |
1892 | to be told about it in the child if you want to continue to use it in the |
1868 | child. |
1893 | child. |
1869 | .PP |
1894 | .PP |
1870 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1895 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
… | |
… | |
1930 | .PD 0 |
1955 | .PD 0 |
1931 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1956 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1932 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1957 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1933 | .PD |
1958 | .PD |
1934 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1959 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1935 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1960 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR, both |
1936 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
1961 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR or \f(CW0\fR, to express the desire to receive the given |
|
|
1962 | events. |
|
|
1963 | .Sp |
|
|
1964 | Note that setting the \f(CW\*(C`events\*(C'\fR to \f(CW0\fR and starting the watcher is |
|
|
1965 | supported, but not specially optimized \- if your program sometimes happens |
|
|
1966 | to generate this combination this is fine, but if it is easy to avoid |
|
|
1967 | starting an io watcher watching for no events you should do so. |
|
|
1968 | .IP "ev_io_modify (ev_io *, int events)" 4 |
|
|
1969 | .IX Item "ev_io_modify (ev_io *, int events)" |
|
|
1970 | Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the requested events. Using this |
|
|
1971 | might be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR |
|
|
1972 | still refers to the same underlying file description, something it cannot |
|
|
1973 | do when using \f(CW\*(C`ev_io_set\*(C'\fR. |
1937 | .IP "int fd [read\-only]" 4 |
1974 | .IP "int fd [no\-modify]" 4 |
1938 | .IX Item "int fd [read-only]" |
1975 | .IX Item "int fd [no-modify]" |
1939 | The file descriptor being watched. |
1976 | The file descriptor being watched. While it can be read at any time, you |
|
|
1977 | must not modify this member even when the watcher is stopped \- always use |
|
|
1978 | \&\f(CW\*(C`ev_io_set\*(C'\fR for that. |
1940 | .IP "int events [read\-only]" 4 |
1979 | .IP "int events [no\-modify]" 4 |
1941 | .IX Item "int events [read-only]" |
1980 | .IX Item "int events [no-modify]" |
1942 | The events being watched. |
1981 | The set of events the fd is being watched for, among other flags. Remember |
|
|
1982 | that this is a bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events & |
|
|
1983 | EV_READ\*(C'\fR, and similarly for \f(CW\*(C`EV_WRITE\*(C'\fR. |
|
|
1984 | .Sp |
|
|
1985 | As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is |
|
|
1986 | stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that. |
1943 | .PP |
1987 | .PP |
1944 | \fIExamples\fR |
1988 | \fIExamples\fR |
1945 | .IX Subsection "Examples" |
1989 | .IX Subsection "Examples" |
1946 | .PP |
1990 | .PP |
1947 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1991 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
… | |
… | |
3958 | .PP |
4002 | .PP |
3959 | First, you need to associate some data with the event loop: |
4003 | First, you need to associate some data with the event loop: |
3960 | .PP |
4004 | .PP |
3961 | .Vb 6 |
4005 | .Vb 6 |
3962 | \& typedef struct { |
4006 | \& typedef struct { |
3963 | \& mutex_t lock; /* global loop lock */ |
4007 | \& pthread_mutex_t lock; /* global loop lock */ |
|
|
4008 | \& pthread_t tid; |
|
|
4009 | \& pthread_cond_t invoke_cv; |
3964 | \& ev_async async_w; |
4010 | \& ev_async async_w; |
3965 | \& thread_t tid; |
|
|
3966 | \& cond_t invoke_cv; |
|
|
3967 | \& } userdata; |
4011 | \& } userdata; |
3968 | \& |
4012 | \& |
3969 | \& void prepare_loop (EV_P) |
4013 | \& void prepare_loop (EV_P) |
3970 | \& { |
4014 | \& { |
3971 | \& // for simplicity, we use a static userdata struct. |
4015 | \& // for simplicity, we use a static userdata struct. |
3972 | \& static userdata u; |
4016 | \& static userdata u; |
3973 | \& |
4017 | \& |
3974 | \& ev_async_init (&u\->async_w, async_cb); |
4018 | \& ev_async_init (&u.async_w, async_cb); |
3975 | \& ev_async_start (EV_A_ &u\->async_w); |
4019 | \& ev_async_start (EV_A_ &u.async_w); |
3976 | \& |
4020 | \& |
3977 | \& pthread_mutex_init (&u\->lock, 0); |
4021 | \& pthread_mutex_init (&u.lock, 0); |
3978 | \& pthread_cond_init (&u\->invoke_cv, 0); |
4022 | \& pthread_cond_init (&u.invoke_cv, 0); |
3979 | \& |
4023 | \& |
3980 | \& // now associate this with the loop |
4024 | \& // now associate this with the loop |
3981 | \& ev_set_userdata (EV_A_ u); |
4025 | \& ev_set_userdata (EV_A_ &u); |
3982 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
4026 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3983 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
4027 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3984 | \& |
4028 | \& |
3985 | \& // then create the thread running ev_run |
4029 | \& // then create the thread running ev_run |
3986 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
4030 | \& pthread_create (&u.tid, 0, l_run, EV_A); |
3987 | \& } |
4031 | \& } |
3988 | .Ve |
4032 | .Ve |
3989 | .PP |
4033 | .PP |
3990 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
4034 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
3991 | solely to wake up the event loop so it takes notice of any new watchers |
4035 | solely to wake up the event loop so it takes notice of any new watchers |
… | |
… | |
4375 | gets automatically stopped and restarted when reconfiguring it with this |
4419 | gets automatically stopped and restarted when reconfiguring it with this |
4376 | method. |
4420 | method. |
4377 | .Sp |
4421 | .Sp |
4378 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
4422 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
4379 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
4423 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
|
|
4424 | .Sp |
|
|
4425 | For \f(CW\*(C`ev::io\*(C'\fR watchers there is an additional \f(CW\*(C`set\*(C'\fR method that acepts a |
|
|
4426 | new event mask only, and internally calls \f(CW\*(C`ev_io_modfify\*(C'\fR. |
4380 | .IP "w\->start ()" 4 |
4427 | .IP "w\->start ()" 4 |
4381 | .IX Item "w->start ()" |
4428 | .IX Item "w->start ()" |
4382 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4429 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4383 | constructor already stores the event loop. |
4430 | constructor already stores the event loop. |
4384 | .IP "w\->start ([arguments])" 4 |
4431 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
4613 | \& |
4660 | \& |
4614 | \& ev_select.c only when select backend is enabled |
4661 | \& ev_select.c only when select backend is enabled |
4615 | \& ev_poll.c only when poll backend is enabled |
4662 | \& ev_poll.c only when poll backend is enabled |
4616 | \& ev_epoll.c only when the epoll backend is enabled |
4663 | \& ev_epoll.c only when the epoll backend is enabled |
4617 | \& ev_linuxaio.c only when the linux aio backend is enabled |
4664 | \& ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4665 | \& ev_iouring.c only when the linux io_uring backend is enabled |
4618 | \& ev_kqueue.c only when the kqueue backend is enabled |
4666 | \& ev_kqueue.c only when the kqueue backend is enabled |
4619 | \& ev_port.c only when the solaris port backend is enabled |
4667 | \& ev_port.c only when the solaris port backend is enabled |
4620 | .Ve |
4668 | .Ve |
4621 | .PP |
4669 | .PP |
4622 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4670 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
… | |
… | |
4735 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4783 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4736 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4784 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4737 | .IX Item "EV_USE_NANOSLEEP" |
4785 | .IX Item "EV_USE_NANOSLEEP" |
4738 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4786 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4739 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
4787 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
4788 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
4789 | .IX Item "EV_USE_EVENTFD" |
|
|
4790 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
4791 | available and will probe for kernel support at runtime. This will improve |
|
|
4792 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
4793 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4794 | 2.7 or newer, otherwise disabled. |
|
|
4795 | .IP "\s-1EV_USE_SIGNALFD\s0" 4 |
|
|
4796 | .IX Item "EV_USE_SIGNALFD" |
|
|
4797 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`signalfd ()\*(C'\fR is |
|
|
4798 | available and will probe for kernel support at runtime. This enables |
|
|
4799 | the use of \s-1EVFLAG_SIGNALFD\s0 for faster and simpler signal handling. If |
|
|
4800 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4801 | 2.7 or newer, otherwise disabled. |
|
|
4802 | .IP "\s-1EV_USE_TIMERFD\s0" 4 |
|
|
4803 | .IX Item "EV_USE_TIMERFD" |
|
|
4804 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`timerfd ()\*(C'\fR is |
|
|
4805 | available and will probe for kernel support at runtime. This allows |
|
|
4806 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4807 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4808 | \&\f(CW\*(C`TFD_TIMER_CANCEL_ON_SET\*(C'\fR, otherwise disabled. |
4740 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4809 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4741 | .IX Item "EV_USE_EVENTFD" |
4810 | .IX Item "EV_USE_EVENTFD" |
4742 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4811 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4743 | available and will probe for kernel support at runtime. This will improve |
4812 | available and will probe for kernel support at runtime. This will improve |
4744 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
4813 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
… | |
… | |
4805 | otherwise another method will be used as fallback. This is the preferred |
4874 | otherwise another method will be used as fallback. This is the preferred |
4806 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4875 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4807 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4876 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4808 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
4877 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
4809 | .IX Item "EV_USE_LINUXAIO" |
4878 | .IX Item "EV_USE_LINUXAIO" |
|
|
4879 | If defined to be \f(CW1\fR, libev will compile in support for the Linux aio |
|
|
4880 | backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be |
|
|
4881 | enabled on linux, otherwise disabled. |
|
|
4882 | .IP "\s-1EV_USE_IOURING\s0" 4 |
|
|
4883 | .IX Item "EV_USE_IOURING" |
4810 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4884 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4811 | aio backend. Due to it's currenbt limitations it has to be requested |
4885 | io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's |
4812 | explicitly. If undefined, it will be enabled on linux, otherwise |
4886 | current limitations it has to be requested explicitly. If undefined, it |
4813 | disabled. |
4887 | will be enabled on linux, otherwise disabled. |
4814 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4888 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4815 | .IX Item "EV_USE_KQUEUE" |
4889 | .IX Item "EV_USE_KQUEUE" |
4816 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4890 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4817 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4891 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4818 | otherwise another method will be used as fallback. This is the preferred |
4892 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
5074 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
5148 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
5075 | called. If set to \f(CW2\fR, then the internal verification code will be |
5149 | called. If set to \f(CW2\fR, then the internal verification code will be |
5076 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5150 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5077 | verification code will be called very frequently, which will slow down |
5151 | verification code will be called very frequently, which will slow down |
5078 | libev considerably. |
5152 | libev considerably. |
|
|
5153 | .Sp |
|
|
5154 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5155 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
5079 | .Sp |
5156 | .Sp |
5080 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5157 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5081 | will be \f(CW0\fR. |
5158 | will be \f(CW0\fR. |
5082 | .IP "\s-1EV_COMMON\s0" 4 |
5159 | .IP "\s-1EV_COMMON\s0" 4 |
5083 | .IX Item "EV_COMMON" |
5160 | .IX Item "EV_COMMON" |