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135.IX Title "LIBEV 3" 135.IX Title "LIBEV 3"
136.TH LIBEV 3 "2018-12-21" "libev-4.25" "libev - high performance full featured event loop" 136.TH LIBEV 3 "2019-06-24" "libev-4.25" "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
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139.if n .ad l 139.if n .ad l
140.nh 140.nh
141.SH "NAME" 141.SH "NAME"
240watchers\fR, which are relatively small C structures you initialise with the 240watchers\fR, which are relatively small C structures you initialise with the
241details of the event, and then hand it over to libev by \fIstarting\fR the 241details of the event, and then hand it over to libev by \fIstarting\fR the
242watcher. 242watcher.
243.SS "\s-1FEATURES\s0" 243.SS "\s-1FEATURES\s0"
244.IX Subsection "FEATURES" 244.IX Subsection "FEATURES"
245Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the 245Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific aio and \f(CW\*(C`epoll\*(C'\fR
246BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms 246interfaces, the BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port
247for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface 247mechanisms for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR
248(for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner 248interface (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner
249inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative 249inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative
250timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling 250timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling
251(\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status 251(\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status
252change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event 252change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event
253loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and 253loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and
392.Sp 392.Sp
393You could override this function in high-availability programs to, say, 393You could override this function in high-availability programs to, say,
394free some memory if it cannot allocate memory, to use a special allocator, 394free some memory if it cannot allocate memory, to use a special allocator,
395or even to sleep a while and retry until some memory is available. 395or even to sleep a while and retry until some memory is available.
396.Sp 396.Sp
397Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses
398which should work with \f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions of all kinds and
399is probably a good basis for your own implementation.
400.Sp
401.Vb 5
402\& static void *
403\& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT
404\& {
405\& if (size)
406\& return realloc (ptr, size);
407\&
408\& free (ptr);
409\& return 0;
410\& }
411.Ve
412.Sp
397Example: Replace the libev allocator with one that waits a bit and then 413Example: Replace the libev allocator with one that waits a bit and then
398retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). 414retries.
399.Sp 415.Sp
400.Vb 6 416.Vb 8
401\& static void * 417\& static void *
402\& persistent_realloc (void *ptr, size_t size) 418\& persistent_realloc (void *ptr, size_t size)
403\& { 419\& {
420\& if (!size)
421\& {
422\& free (ptr);
423\& return 0;
424\& }
425\&
404\& for (;;) 426\& for (;;)
405\& { 427\& {
406\& void *newptr = realloc (ptr, size); 428\& void *newptr = realloc (ptr, size);
407\& 429\&
408\& if (newptr) 430\& if (newptr)
585.Sp 607.Sp
586This flag's behaviour will become the default in future versions of libev. 608This flag's behaviour will become the default in future versions of libev.
587.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 609.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
588.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 610.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
589.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 611.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
590This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 612This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
591libev tries to roll its own fd_set with no limits on the number of fds, 613libev tries to roll its own fd_set with no limits on the number of fds,
592but if that fails, expect a fairly low limit on the number of fds when 614but if that fails, expect a fairly low limit on the number of fds when
593using this backend. It doesn't scale too well (O(highest_fd)), but its 615using this backend. It doesn't scale too well (O(highest_fd)), but its
594usually the fastest backend for a low number of (low-numbered :) fds. 616usually the fastest backend for a low number of (low-numbered :) fds.
595.Sp 617.Sp
604\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the 626\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the
605\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). 627\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform).
606.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 628.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
607.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 629.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
608.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" 630.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
609And this is your standard \fIpoll\fR\|(2) backend. It's more complicated 631And this is your standard \fBpoll\fR\|(2) backend. It's more complicated
610than select, but handles sparse fds better and has no artificial 632than select, but handles sparse fds better and has no artificial
611limit on the number of fds you can use (except it will slow down 633limit on the number of fds you can use (except it will slow down
612considerably with a lot of inactive fds). It scales similarly to select, 634considerably with a lot of inactive fds). It scales similarly to select,
613i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for 635i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for
614performance tips. 636performance tips.
616This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and 638This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and
617\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. 639\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR.
618.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 640.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
619.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 641.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
620.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 642.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
621Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 643Use the linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9
622kernels). 644kernels).
623.Sp 645.Sp
624For few fds, this backend is a bit little slower than poll and select, but 646For few fds, this backend is a bit little slower than poll and select, but
625it scales phenomenally better. While poll and select usually scale like 647it scales phenomenally better. While poll and select usually scale like
626O(total_fds) where total_fds is the total number of fds (or the highest 648O(total_fds) where total_fds is the total number of fds (or the highest
672All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or 694All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or
673faster than epoll for maybe up to a hundred file descriptors, depending on 695faster than epoll for maybe up to a hundred file descriptors, depending on
674the usage. So sad. 696the usage. So sad.
675.Sp 697.Sp
676While nominally embeddable in other event loops, this feature is broken in 698While nominally embeddable in other event loops, this feature is broken in
677all kernel versions tested so far. 699a lot of kernel revisions, but probably(!) works in current versions.
700.Sp
701This 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.
703.ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4
704.el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4
705.IX Item "EVBACKEND_LINUXAIO (value 64, Linux)"
706Use 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.
707.Sp
708If this backend works for you (as of this writing, it was very
709experimental), it is the best event interface available on linux and might
710be well worth enabling it \- if it isn't available in your kernel this will
711be detected and this backend will be skipped.
712.Sp
713This backend can batch oneshot requests and supports a user-space ring
714buffer to receive events. It also doesn't suffer from most of the design
715problems of epoll (such as not being able to remove event sources from the
716epoll set), and generally sounds too good to be true. Because, this being
717the linux kernel, of course it suffers from a whole new set of limitations.
718.Sp
719For one, it is not easily embeddable (but probably could be done using
720an event fd at some extra overhead). It also is subject to a system wide
721limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR \- each loop
722currently requires \f(CW61\fR of this number. If no aio requests are left, this
723backend will be skipped during initialisation.
724.Sp
725Most problematic in practise, however, is that not all file descriptors
726work with it. For example, in linux 5.1, tcp sockets, pipes, event fds,
727files, \fI/dev/null\fR and a few others are supported, but ttys do not work
728properly (a known bug that the kernel developers don't care about, see
729<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not
730(yet?) a generic event polling interface.
731.Sp
732Overall, it seems the linux developers just don't want it to have a
733generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR.
734.Sp
735To work around the fd type problem, the current version of libev uses
736epoll as a fallback for file deescriptor types that do not work. Epoll
737is used in, kind of, slow mode that hopefully avoids most of its design
738problems and requires 1\-3 extra syscalls per active fd every iteration.
678.Sp 739.Sp
679This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as 740This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as
680\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. 741\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
681.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 742.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
682.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 743.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
785Example: Use whatever libev has to offer, but make sure that kqueue is 846Example: Use whatever libev has to offer, but make sure that kqueue is
786used if available. 847used if available.
787.Sp 848.Sp
788.Vb 1 849.Vb 1
789\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); 850\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
851.Ve
852.Sp
853Example: Similarly, on linux, you mgiht want to take advantage of the
854linux aio backend if possible, but fall back to something else if that
855isn't available.
856.Sp
857.Vb 1
858\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO);
790.Ve 859.Ve
791.RE 860.RE
792.IP "ev_loop_destroy (loop)" 4 861.IP "ev_loop_destroy (loop)" 4
793.IX Item "ev_loop_destroy (loop)" 862.IX Item "ev_loop_destroy (loop)"
794Destroys an event loop object (frees all memory and kernel state 863Destroys an event loop object (frees all memory and kernel state
1365bug in your program. 1434bug in your program.
1366.Sp 1435.Sp
1367Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for 1436Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for
1368example it might indicate that a fd is readable or writable, and if your 1437example it might indicate that a fd is readable or writable, and if your
1369callbacks is well-written it can just attempt the operation and cope with 1438callbacks is well-written it can just attempt the operation and cope with
1370the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded 1439the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded
1371programs, though, as the fd could already be closed and reused for another 1440programs, though, as the fd could already be closed and reused for another
1372thing, so beware. 1441thing, so beware.
1373.SS "\s-1GENERIC WATCHER FUNCTIONS\s0" 1442.SS "\s-1GENERIC WATCHER FUNCTIONS\s0"
1374.IX Subsection "GENERIC WATCHER FUNCTIONS" 1443.IX Subsection "GENERIC WATCHER FUNCTIONS"
1375.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1444.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1726But really, best use non-blocking mode. 1795But really, best use non-blocking mode.
1727.PP 1796.PP
1728\fIThe special problem of disappearing file descriptors\fR 1797\fIThe special problem of disappearing file descriptors\fR
1729.IX Subsection "The special problem of disappearing file descriptors" 1798.IX Subsection "The special problem of disappearing file descriptors"
1730.PP 1799.PP
1731Some backends (e.g. kqueue, epoll) need to be told about closing a file 1800Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing
1732descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, 1801a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other
1733such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file 1802means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some
1734descriptor, but when it goes away, the operating system will silently drop 1803file descriptor, but when it goes away, the operating system will silently
1735this interest. If another file descriptor with the same number then is 1804drop this interest. If another file descriptor with the same number then
1736registered with libev, there is no efficient way to see that this is, in 1805is registered with libev, there is no efficient way to see that this is,
1737fact, a different file descriptor. 1806in fact, a different file descriptor.
1738.PP 1807.PP
1739To avoid having to explicitly tell libev about such cases, libev follows 1808To avoid having to explicitly tell libev about such cases, libev follows
1740the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev 1809the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1741will assume that this is potentially a new file descriptor, otherwise 1810will assume that this is potentially a new file descriptor, otherwise
1742it is assumed that the file descriptor stays the same. That means that 1811it is assumed that the file descriptor stays the same. That means that
1794reuse the same code path. 1863reuse the same code path.
1795.PP 1864.PP
1796\fIThe special problem of fork\fR 1865\fIThe special problem of fork\fR
1797.IX Subsection "The special problem of fork" 1866.IX Subsection "The special problem of fork"
1798.PP 1867.PP
1799Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit 1868Some backends (epoll, kqueue, probably linuxaio) do not support \f(CW\*(C`fork ()\*(C'\fR
1800useless behaviour. Libev fully supports fork, but needs to be told about 1869at all or exhibit useless behaviour. Libev fully supports fork, but needs
1801it in the child if you want to continue to use it in the child. 1870to be told about it in the child if you want to continue to use it in the
1871child.
1802.PP 1872.PP
1803To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork 1873To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork
1804()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to 1874()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to
1805\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. 1875\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1806.PP 1876.PP
1811when writing to a pipe whose other end has been closed, your program gets 1881when writing to a pipe whose other end has been closed, your program gets
1812sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs 1882sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs
1813this is sensible behaviour, for daemons, this is usually undesirable. 1883this is sensible behaviour, for daemons, this is usually undesirable.
1814.PP 1884.PP
1815So when you encounter spurious, unexplained daemon exits, make sure you 1885So when you encounter spurious, unexplained daemon exits, make sure you
1816ignore \s-1SIGPIPE \s0(and maybe make sure you log the exit status of your daemon 1886ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon
1817somewhere, as that would have given you a big clue). 1887somewhere, as that would have given you a big clue).
1818.PP 1888.PP
1819\fIThe special problem of \fIaccept()\fIing when you can't\fR 1889\fIThe special problem of \f(BIaccept()\fIing when you can't\fR
1820.IX Subsection "The special problem of accept()ing when you can't" 1890.IX Subsection "The special problem of accept()ing when you can't"
1821.PP 1891.PP
1822Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example, 1892Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example,
1823found in post\-2004 Linux) have the peculiar behaviour of not removing a 1893found in post\-2004 Linux) have the peculiar behaviour of not removing a
1824connection from the pending queue in all error cases. 1894connection from the pending queue in all error cases.
1825.PP 1895.PP
1826For example, larger servers often run out of file descriptors (because 1896For example, larger servers often run out of file descriptors (because
1827of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not 1897of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not
2434In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being 2504In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being
2435ignored. Instead, each time the periodic watcher gets scheduled, the 2505ignored. Instead, each time the periodic watcher gets scheduled, the
2436reschedule callback will be called with the watcher as first, and the 2506reschedule callback will be called with the watcher as first, and the
2437current time as second argument. 2507current time as second argument.
2438.Sp 2508.Sp
2439\&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, 2509\&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever,
2440or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly 2510or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly
2441allowed by documentation here\fR. 2511allowed by documentation here\fR.
2442.Sp 2512.Sp
2443If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop 2513If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop
2444it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the 2514it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the
2458It must return the next time to trigger, based on the passed time value 2528It must return the next time to trigger, based on the passed time value
2459(that is, the lowest time value larger than to the second argument). It 2529(that is, the lowest time value larger than to the second argument). It
2460will usually be called just before the callback will be triggered, but 2530will usually be called just before the callback will be triggered, but
2461might be called at other times, too. 2531might be called at other times, too.
2462.Sp 2532.Sp
2463\&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or 2533\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or
2464equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. 2534equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
2465.Sp 2535.Sp
2466This can be used to create very complex timers, such as a timer that 2536This can be used to create very complex timers, such as a timer that
2467triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate 2537triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate
2468the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for 2538the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for
2613The simplest way to ensure that the signal mask is reset in the child is 2683The simplest way to ensure that the signal mask is reset in the child is
2614to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will 2684to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will
2615catch fork calls done by libraries (such as the libc) as well. 2685catch fork calls done by libraries (such as the libc) as well.
2616.PP 2686.PP
2617In current versions of libev, the signal will not be blocked indefinitely 2687In current versions of libev, the signal will not be blocked indefinitely
2618unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces 2688unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces
2619the window of opportunity for problems, it will not go away, as libev 2689the window of opportunity for problems, it will not go away, as libev
2620\&\fIhas\fR to modify the signal mask, at least temporarily. 2690\&\fIhas\fR to modify the signal mask, at least temporarily.
2621.PP 2691.PP
2622So I can't stress this enough: \fIIf you do not reset your signal mask when 2692So I can't stress this enough: \fIIf you do not reset your signal mask when
2623you expect it to be empty, you have a race condition in your code\fR. This 2693you expect it to be empty, you have a race condition in your code\fR. This
4518\& #include "ev.c" 4588\& #include "ev.c"
4519.Ve 4589.Ve
4520.PP 4590.PP
4521This will automatically include \fIev.h\fR, too, and should be done in a 4591This will automatically include \fIev.h\fR, too, and should be done in a
4522single C source file only to provide the function implementations. To use 4592single C source file only to provide the function implementations. To use
4523it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best 4593it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
4524done by writing a wrapper around \fIev.h\fR that you can include instead and 4594done by writing a wrapper around \fIev.h\fR that you can include instead and
4525where you can put other configuration options): 4595where you can put other configuration options):
4526.PP 4596.PP
4527.Vb 2 4597.Vb 2
4528\& #define EV_STANDALONE 1 4598\& #define EV_STANDALONE 1
4545\& ev_win32.c required on win32 platforms only 4615\& ev_win32.c required on win32 platforms only
4546\& 4616\&
4547\& ev_select.c only when select backend is enabled 4617\& ev_select.c only when select backend is enabled
4548\& ev_poll.c only when poll backend is enabled 4618\& ev_poll.c only when poll backend is enabled
4549\& ev_epoll.c only when the epoll backend is enabled 4619\& ev_epoll.c only when the epoll backend is enabled
4620\& ev_linuxaio.c only when the linux aio backend is enabled
4550\& ev_kqueue.c only when the kqueue backend is enabled 4621\& ev_kqueue.c only when the kqueue backend is enabled
4551\& ev_port.c only when the solaris port backend is enabled 4622\& ev_port.c only when the solaris port backend is enabled
4552.Ve 4623.Ve
4553.PP 4624.PP
4554\&\fIev.c\fR includes the backend files directly when enabled, so you only need 4625\&\fIev.c\fR includes the backend files directly when enabled, so you only need
4601values when compiling libev vs. including \fIev.h\fR, so it is permissible 4672values when compiling libev vs. including \fIev.h\fR, so it is permissible
4602to redefine them before including \fIev.h\fR without breaking compatibility 4673to redefine them before including \fIev.h\fR without breaking compatibility
4603to a compiled library. All other symbols change the \s-1ABI,\s0 which means all 4674to a compiled library. All other symbols change the \s-1ABI,\s0 which means all
4604users of libev and the libev code itself must be compiled with compatible 4675users of libev and the libev code itself must be compiled with compatible
4605settings. 4676settings.
4606.IP "\s-1EV_COMPAT3 \s0(h)" 4 4677.IP "\s-1EV_COMPAT3\s0 (h)" 4
4607.IX Item "EV_COMPAT3 (h)" 4678.IX Item "EV_COMPAT3 (h)"
4608Backwards compatibility is a major concern for libev. This is why this 4679Backwards compatibility is a major concern for libev. This is why this
4609release of libev comes with wrappers for the functions and symbols that 4680release of libev comes with wrappers for the functions and symbols that
4610have been renamed between libev version 3 and 4. 4681have been renamed between libev version 3 and 4.
4611.Sp 4682.Sp
4616typedef in that case. 4687typedef in that case.
4617.Sp 4688.Sp
4618In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, 4689In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR,
4619and in some even more future version the compatibility code will be 4690and in some even more future version the compatibility code will be
4620removed completely. 4691removed completely.
4621.IP "\s-1EV_STANDALONE \s0(h)" 4 4692.IP "\s-1EV_STANDALONE\s0 (h)" 4
4622.IX Item "EV_STANDALONE (h)" 4693.IX Item "EV_STANDALONE (h)"
4623Must always be \f(CW1\fR if you do not use autoconf configuration, which 4694Must always be \f(CW1\fR if you do not use autoconf configuration, which
4624keeps libev from including \fIconfig.h\fR, and it also defines dummy 4695keeps libev from including \fIconfig.h\fR, and it also defines dummy
4625implementations for some libevent functions (such as logging, which is not 4696implementations for some libevent functions (such as logging, which is not
4626supported). It will also not define any of the structs usually found in 4697supported). It will also not define any of the structs usually found in
4735If defined to be \f(CW1\fR, libev will compile in support for the Linux 4806If defined to be \f(CW1\fR, libev will compile in support for the Linux
4736\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, 4807\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
4737otherwise another method will be used as fallback. This is the preferred 4808otherwise another method will be used as fallback. This is the preferred
4738backend for GNU/Linux systems. If undefined, it will be enabled if the 4809backend for GNU/Linux systems. If undefined, it will be enabled if the
4739headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. 4810headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
4811.IP "\s-1EV_USE_LINUXAIO\s0" 4
4812.IX Item "EV_USE_LINUXAIO"
4813If defined to be \f(CW1\fR, libev will compile in support for the Linux
4814aio backend. Due to it's currenbt limitations it has to be requested
4815explicitly. If undefined, it will be enabled on linux, otherwise
4816disabled.
4740.IP "\s-1EV_USE_KQUEUE\s0" 4 4817.IP "\s-1EV_USE_KQUEUE\s0" 4
4741.IX Item "EV_USE_KQUEUE" 4818.IX Item "EV_USE_KQUEUE"
4742If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style 4819If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
4743\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, 4820\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
4744otherwise another method will be used as fallback. This is the preferred 4821otherwise another method will be used as fallback. This is the preferred
4784handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR 4861handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR
4785watchers. 4862watchers.
4786.Sp 4863.Sp
4787In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR 4864In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR
4788(from \fIsignal.h\fR), which is usually good enough on most platforms. 4865(from \fIsignal.h\fR), which is usually good enough on most platforms.
4789.IP "\s-1EV_H \s0(h)" 4 4866.IP "\s-1EV_H\s0 (h)" 4
4790.IX Item "EV_H (h)" 4867.IX Item "EV_H (h)"
4791The name of the \fIev.h\fR header file used to include it. The default if 4868The name of the \fIev.h\fR header file used to include it. The default if
4792undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be 4869undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be
4793used to virtually rename the \fIev.h\fR header file in case of conflicts. 4870used to virtually rename the \fIev.h\fR header file in case of conflicts.
4794.IP "\s-1EV_CONFIG_H \s0(h)" 4 4871.IP "\s-1EV_CONFIG_H\s0 (h)" 4
4795.IX Item "EV_CONFIG_H (h)" 4872.IX Item "EV_CONFIG_H (h)"
4796If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override 4873If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
4797\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to 4874\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
4798\&\f(CW\*(C`EV_H\*(C'\fR, above. 4875\&\f(CW\*(C`EV_H\*(C'\fR, above.
4799.IP "\s-1EV_EVENT_H \s0(h)" 4 4876.IP "\s-1EV_EVENT_H\s0 (h)" 4
4800.IX Item "EV_EVENT_H (h)" 4877.IX Item "EV_EVENT_H (h)"
4801Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea 4878Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
4802of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. 4879of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR.
4803.IP "\s-1EV_PROTOTYPES \s0(h)" 4 4880.IP "\s-1EV_PROTOTYPES\s0 (h)" 4
4804.IX Item "EV_PROTOTYPES (h)" 4881.IX Item "EV_PROTOTYPES (h)"
4805If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function 4882If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
4806prototypes, but still define all the structs and other symbols. This is 4883prototypes, but still define all the structs and other symbols. This is
4807occasionally useful if you want to provide your own wrapper functions 4884occasionally useful if you want to provide your own wrapper functions
4808around libev functions. 4885around libev functions.
5017.Vb 3 5094.Vb 3
5018\& #define EV_COMMON \e 5095\& #define EV_COMMON \e
5019\& SV *self; /* contains this struct */ \e 5096\& SV *self; /* contains this struct */ \e
5020\& SV *cb_sv, *fh /* note no trailing ";" */ 5097\& SV *cb_sv, *fh /* note no trailing ";" */
5021.Ve 5098.Ve
5022.IP "\s-1EV_CB_DECLARE \s0(type)" 4 5099.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
5023.IX Item "EV_CB_DECLARE (type)" 5100.IX Item "EV_CB_DECLARE (type)"
5024.PD 0 5101.PD 0
5025.IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 5102.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
5026.IX Item "EV_CB_INVOKE (watcher, revents)" 5103.IX Item "EV_CB_INVOKE (watcher, revents)"
5027.IP "ev_set_cb (ev, cb)" 4 5104.IP "ev_set_cb (ev, cb)" 4
5028.IX Item "ev_set_cb (ev, cb)" 5105.IX Item "ev_set_cb (ev, cb)"
5029.PD 5106.PD
5030Can be used to change the callback member declaration in each watcher, 5107Can be used to change the callback member declaration in each watcher,
5033their default definitions. One possible use for overriding these is to 5110their default definitions. One possible use for overriding these is to
5034avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 5111avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
5035method calls instead of plain function calls in \*(C+. 5112method calls instead of plain function calls in \*(C+.
5036.SS "\s-1EXPORTED API SYMBOLS\s0" 5113.SS "\s-1EXPORTED API SYMBOLS\s0"
5037.IX Subsection "EXPORTED API SYMBOLS" 5114.IX Subsection "EXPORTED API SYMBOLS"
5038If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of 5115If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of
5039exported symbols, you can use the provided \fISymbol.*\fR files which list 5116exported symbols, you can use the provided \fISymbol.*\fR files which list
5040all public symbols, one per line: 5117all public symbols, one per line:
5041.PP 5118.PP
5042.Vb 2 5119.Vb 2
5043\& Symbols.ev for libev proper 5120\& Symbols.ev for libev proper
5275.PP 5352.PP
5276\fI\f(CI\*(C`select\*(C'\fI is buggy\fR 5353\fI\f(CI\*(C`select\*(C'\fI is buggy\fR
5277.IX Subsection "select is buggy" 5354.IX Subsection "select is buggy"
5278.PP 5355.PP
5279All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this 5356All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this
5280one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file 5357one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file
5281descriptors you can pass in to 1024 \- your program suddenly crashes when 5358descriptors you can pass in to 1024 \- your program suddenly crashes when
5282you use more. 5359you use more.
5283.PP 5360.PP
5284There is an undocumented \*(L"workaround\*(R" for this \- defining 5361There is an undocumented \*(L"workaround\*(R" for this \- defining
5285\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR 5362\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR

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