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126.IX Title "LIBEV 3" 135.IX Title "LIBEV 3"
127.TH LIBEV 3 "2012-05-06" "libev-4.11" "libev - high performance full featured event loop" 136.TH LIBEV 3 "2020-01-22" "libev-4.31" "libev - high performance full featured event loop"
128.\" For nroff, turn off justification. Always turn off hyphenation; it makes 137.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents. 138.\" way too many mistakes in technical documents.
130.if n .ad l 139.if n .ad l
131.nh 140.nh
132.SH "NAME" 141.SH "NAME"
134.SH "SYNOPSIS" 143.SH "SYNOPSIS"
135.IX Header "SYNOPSIS" 144.IX Header "SYNOPSIS"
136.Vb 1 145.Vb 1
137\& #include <ev.h> 146\& #include <ev.h>
138.Ve 147.Ve
139.SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" 148.SS "\s-1EXAMPLE PROGRAM\s0"
140.IX Subsection "EXAMPLE PROGRAM" 149.IX Subsection "EXAMPLE PROGRAM"
141.Vb 2 150.Vb 2
142\& // a single header file is required 151\& // a single header file is required
143\& #include <ev.h> 152\& #include <ev.h>
144\& 153\&
212throughout this document. 221throughout this document.
213.SH "WHAT TO READ WHEN IN A HURRY" 222.SH "WHAT TO READ WHEN IN A HURRY"
214.IX Header "WHAT TO READ WHEN IN A HURRY" 223.IX Header "WHAT TO READ WHEN IN A HURRY"
215This manual tries to be very detailed, but unfortunately, this also makes 224This manual tries to be very detailed, but unfortunately, this also makes
216it very long. If you just want to know the basics of libev, I suggest 225it very long. If you just want to know the basics of libev, I suggest
217reading \*(L"\s-1ANATOMY\s0 \s-1OF\s0 A \s-1WATCHER\s0\*(R", then the \*(L"\s-1EXAMPLE\s0 \s-1PROGRAM\s0\*(R" above and 226reading \*(L"\s-1ANATOMY OF A WATCHER\*(R"\s0, then the \*(L"\s-1EXAMPLE PROGRAM\*(R"\s0 above and
218look up the missing functions in \*(L"\s-1GLOBAL\s0 \s-1FUNCTIONS\s0\*(R" and the \f(CW\*(C`ev_io\*(C'\fR and 227look up the missing functions in \*(L"\s-1GLOBAL FUNCTIONS\*(R"\s0 and the \f(CW\*(C`ev_io\*(C'\fR and
219\&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". 228\&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER TYPES\*(R"\s0.
220.SH "ABOUT LIBEV" 229.SH "ABOUT LIBEV"
221.IX Header "ABOUT LIBEV" 230.IX Header "ABOUT LIBEV"
222Libev is an event loop: you register interest in certain events (such as a 231Libev is an event loop: you register interest in certain events (such as a
223file descriptor being readable or a timeout occurring), and it will manage 232file descriptor being readable or a timeout occurring), and it will manage
224these event sources and provide your program with events. 233these event sources and provide your program with events.
231watchers\fR, which are relatively small C structures you initialise with the 240watchers\fR, which are relatively small C structures you initialise with the
232details 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
233watcher. 242watcher.
234.SS "\s-1FEATURES\s0" 243.SS "\s-1FEATURES\s0"
235.IX Subsection "FEATURES" 244.IX Subsection "FEATURES"
236Libev 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
237BSD-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
238for 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
239(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
240inter-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
241timers (\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
242(\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
243change 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
244loop 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
255more info about various configuration options please have a look at 264more info about various configuration options please have a look at
256\&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support 265\&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support
257for multiple event loops, then all functions taking an initial argument of 266for multiple event loops, then all functions taking an initial argument of
258name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have 267name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have
259this argument. 268this argument.
260.SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" 269.SS "\s-1TIME REPRESENTATION\s0"
261.IX Subsection "TIME REPRESENTATION" 270.IX Subsection "TIME REPRESENTATION"
262Libev represents time as a single floating point number, representing 271Libev represents time as a single floating point number, representing
263the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice 272the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice
264somewhere near the beginning of 1970, details are complicated, don't 273somewhere near the beginning of 1970, details are complicated, don't
265ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use 274ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use
282When libev detects a usage error such as a negative timer interval, then 291When libev detects a usage error such as a negative timer interval, then
283it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, 292it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism,
284so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in 293so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in
285the libev caller and need to be fixed there. 294the libev caller and need to be fixed there.
286.PP 295.PP
296Via the \f(CW\*(C`EV_FREQUENT\*(C'\fR macro you can compile in and/or enable extensive
297consistency checking code inside libev that can be used to check for
298internal inconsistencies, suually caused by application bugs.
299.PP
287Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has 300Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions. These do not
288extensive consistency checking code. These do not trigger under normal
289circumstances, as they indicate either a bug in libev or worse. 301trigger under normal circumstances, as they indicate either a bug in libev
302or worse.
290.SH "GLOBAL FUNCTIONS" 303.SH "GLOBAL FUNCTIONS"
291.IX Header "GLOBAL FUNCTIONS" 304.IX Header "GLOBAL FUNCTIONS"
292These functions can be called anytime, even before initialising the 305These functions can be called anytime, even before initialising the
293library in any way. 306library in any way.
294.IP "ev_tstamp ev_time ()" 4 307.IP "ev_tstamp ev_time ()" 4
383.Sp 396.Sp
384You could override this function in high-availability programs to, say, 397You could override this function in high-availability programs to, say,
385free some memory if it cannot allocate memory, to use a special allocator, 398free some memory if it cannot allocate memory, to use a special allocator,
386or even to sleep a while and retry until some memory is available. 399or even to sleep a while and retry until some memory is available.
387.Sp 400.Sp
401Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses
402which should work with \f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions of all kinds and
403is probably a good basis for your own implementation.
404.Sp
405.Vb 5
406\& static void *
407\& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT
408\& {
409\& if (size)
410\& return realloc (ptr, size);
411\&
412\& free (ptr);
413\& return 0;
414\& }
415.Ve
416.Sp
388Example: Replace the libev allocator with one that waits a bit and then 417Example: Replace the libev allocator with one that waits a bit and then
389retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). 418retries.
390.Sp 419.Sp
391.Vb 6 420.Vb 8
392\& static void * 421\& static void *
393\& persistent_realloc (void *ptr, size_t size) 422\& persistent_realloc (void *ptr, size_t size)
394\& { 423\& {
424\& if (!size)
425\& {
426\& free (ptr);
427\& return 0;
428\& }
429\&
395\& for (;;) 430\& for (;;)
396\& { 431\& {
397\& void *newptr = realloc (ptr, size); 432\& void *newptr = realloc (ptr, size);
398\& 433\&
399\& if (newptr) 434\& if (newptr)
514.IX Item "EVFLAG_NOENV" 549.IX Item "EVFLAG_NOENV"
515If this flag bit is or'ed into the flag value (or the program runs setuid 550If this flag bit is or'ed into the flag value (or the program runs setuid
516or setgid) then libev will \fInot\fR look at the environment variable 551or setgid) then libev will \fInot\fR look at the environment variable
517\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 552\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
518override the flags completely if it is found in the environment. This is 553override the flags completely if it is found in the environment. This is
519useful to try out specific backends to test their performance, or to work 554useful to try out specific backends to test their performance, to work
520around bugs. 555around bugs, or to make libev threadsafe (accessing environment variables
556cannot be done in a threadsafe way, but usually it works if no other
557thread modifies them).
521.ie n .IP """EVFLAG_FORKCHECK""" 4 558.ie n .IP """EVFLAG_FORKCHECK""" 4
522.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 559.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
523.IX Item "EVFLAG_FORKCHECK" 560.IX Item "EVFLAG_FORKCHECK"
524Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also 561Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also
525make libev check for a fork in each iteration by enabling this flag. 562make libev check for a fork in each iteration by enabling this flag.
526.Sp 563.Sp
527This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, 564This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
528and thus this might slow down your event loop if you do a lot of loop 565and thus this might slow down your event loop if you do a lot of loop
529iterations and little real work, but is usually not noticeable (on my 566iterations and little real work, but is usually not noticeable (on my
530GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence 567GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn
531without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has 568sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux
532\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). 569system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc
570versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again).
533.Sp 571.Sp
534The big advantage of this flag is that you can forget about fork (and 572The big advantage of this flag is that you can forget about fork (and
535forget about forgetting to tell libev about forking) when you use this 573forget about forgetting to tell libev about forking, although you still
536flag. 574have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag.
537.Sp 575.Sp
538This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR 576This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
539environment variable. 577environment variable.
540.ie n .IP """EVFLAG_NOINOTIFY""" 4 578.ie n .IP """EVFLAG_NOINOTIFY""" 4
541.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 579.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4
568want to handle signals only in specific threads and want to avoid libev 606want to handle signals only in specific threads and want to avoid libev
569unblocking the signals. 607unblocking the signals.
570.Sp 608.Sp
571It's also required by \s-1POSIX\s0 in a threaded program, as libev calls 609It's also required by \s-1POSIX\s0 in a threaded program, as libev calls
572\&\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"
614When this flag is specified, the libev will avoid using a \f(CW\*(C`timerfd\*(C'\fR to
615detect time jumps. It will still be able to detect time jumps, but takes
616longer and has a lower accuracy in doing so, but saves a file descriptor
617per loop.
573.Sp 618.Sp
574This flag's behaviour will become the default in future versions of libev. 619The 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
621cannot be created, but this behaviour might change in the future.
575.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 622.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
576.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
577.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 624.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
578This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 625This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
579libev tries to roll its own fd_set with no limits on the number of fds, 626libev tries to roll its own fd_set with no limits on the number of fds,
580but if that fails, expect a fairly low limit on the number of fds when 627but if that fails, expect a fairly low limit on the number of fds when
581using this backend. It doesn't scale too well (O(highest_fd)), but its 628using this backend. It doesn't scale too well (O(highest_fd)), but its
582usually the fastest backend for a low number of (low-numbered :) fds. 629usually the fastest backend for a low number of (low-numbered :) fds.
583.Sp 630.Sp
591This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the 638This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the
592\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the 639\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the
593\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). 640\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform).
594.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 641.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
595.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 642.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
596.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" 643.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
597And this is your standard \fIpoll\fR\|(2) backend. It's more complicated 644And this is your standard \fBpoll\fR\|(2) backend. It's more complicated
598than select, but handles sparse fds better and has no artificial 645than select, but handles sparse fds better and has no artificial
599limit on the number of fds you can use (except it will slow down 646limit on the number of fds you can use (except it will slow down
600considerably with a lot of inactive fds). It scales similarly to select, 647considerably with a lot of inactive fds). It scales similarly to select,
601i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for 648i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for
602performance tips. 649performance tips.
603.Sp 650.Sp
604This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and 651This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and
605\&\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.
606.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 653.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
607.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 654.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
608.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 655.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
609Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 656Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9
610kernels). 657kernels).
611.Sp 658.Sp
612For few fds, this backend is a bit little slower than poll and select, but 659For few fds, this backend is a bit little slower than poll and select, but
613it scales phenomenally better. While poll and select usually scale like 660it scales phenomenally better. While poll and select usually scale like
614O(total_fds) where total_fds is the total number of fds (or the highest 661O(total_fds) where total_fds is the total number of fds (or the highest
660All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or 707All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or
661faster than epoll for maybe up to a hundred file descriptors, depending on 708faster than epoll for maybe up to a hundred file descriptors, depending on
662the usage. So sad. 709the usage. So sad.
663.Sp 710.Sp
664While nominally embeddable in other event loops, this feature is broken in 711While nominally embeddable in other event loops, this feature is broken in
665all kernel versions tested so far. 712a lot of kernel revisions, but probably(!) works in current versions.
713.Sp
714This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as
715\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
716.ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4
717.el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4
718.IX Item "EVBACKEND_LINUXAIO (value 64, Linux)"
719Use 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
720only tries to use it in 4.19+).
721.Sp
722This is another Linux train wreck of an event interface.
723.Sp
724If this backend works for you (as of this writing, it was very
725experimental), it is the best event interface available on Linux and might
726be well worth enabling it \- if it isn't available in your kernel this will
727be detected and this backend will be skipped.
728.Sp
729This backend can batch oneshot requests and supports a user-space ring
730buffer to receive events. It also doesn't suffer from most of the design
731problems of epoll (such as not being able to remove event sources from
732the epoll set), and generally sounds too good to be true. Because, this
733being the Linux kernel, of course it suffers from a whole new set of
734limitations, forcing you to fall back to epoll, inheriting all its design
735issues.
736.Sp
737For one, it is not easily embeddable (but probably could be done using
738an event fd at some extra overhead). It also is subject to a system wide
739limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0
740requests are left, this backend will be skipped during initialisation, and
741will switch to epoll when the loop is active.
742.Sp
743Most problematic in practice, however, is that not all file descriptors
744work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds,
745files, \fI/dev/null\fR and many others are supported, but ttys do not work
746properly (a known bug that the kernel developers don't care about, see
747<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not
748(yet?) a generic event polling interface.
749.Sp
750Overall, it seems the Linux developers just don't want it to have a
751generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR.
752.Sp
753To work around all these problem, the current version of libev uses its
754epoll backend as a fallback for file descriptor types that do not work. Or
755falls back completely to epoll if the kernel acts up.
666.Sp 756.Sp
667This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as 757This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as
668\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. 758\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
669.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
670.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
671.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 761.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
672Kqueue deserves special mention, as at the time of this writing, it 762Kqueue deserves special mention, as at the time this backend was
673was broken on all BSDs except NetBSD (usually it doesn't work reliably 763implemented, it was broken on all BSDs except NetBSD (usually it doesn't
674with anything but sockets and pipes, except on Darwin, where of course 764work reliably with anything but sockets and pipes, except on Darwin,
675it's completely useless). Unlike epoll, however, whose brokenness 765where of course it's completely useless). Unlike epoll, however, whose
676is by design, these kqueue bugs can (and eventually will) be fixed 766brokenness is by design, these kqueue bugs can be (and mostly have been)
677without \s-1API\s0 changes to existing programs. For this reason it's not being 767fixed without \s-1API\s0 changes to existing programs. For this reason it's not
678\&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using 768being \*(L"auto-detected\*(R" on all platforms unless you explicitly specify it
679\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) 769in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a
680system like NetBSD. 770known-to-be-good (\-enough) system like NetBSD.
681.Sp 771.Sp
682You still can embed kqueue into a normal poll or select backend and use it 772You still can embed kqueue into a normal poll or select backend and use it
683only for sockets (after having made sure that sockets work with kqueue on 773only for sockets (after having made sure that sockets work with kqueue on
684the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 774the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
685.Sp 775.Sp
686It scales in the same way as the epoll backend, but the interface to the 776It scales in the same way as the epoll backend, but the interface to the
687kernel is more efficient (which says nothing about its actual speed, of 777kernel is more efficient (which says nothing about its actual speed, of
688course). While stopping, setting and starting an I/O watcher does never 778course). While stopping, setting and starting an I/O watcher does never
689cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to 779cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
690two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you 780two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you
691might have to leak fd's on fork, but it's more sane than epoll) and it 781might have to leak fds on fork, but it's more sane than epoll) and it
692drops fds silently in similarly hard-to-detect cases 782drops fds silently in similarly hard-to-detect cases.
693.Sp 783.Sp
694This backend usually performs well under most conditions. 784This backend usually performs well under most conditions.
695.Sp 785.Sp
696While nominally embeddable in other event loops, this doesn't work 786While nominally embeddable in other event loops, this doesn't work
697everywhere, so you might need to test for this. And since it is broken 787everywhere, so you might need to test for this. And since it is broken
698almost everywhere, you should only use it when you have a lot of sockets 788almost everywhere, you should only use it when you have a lot of sockets
699(for which it usually works), by embedding it into another event loop 789(for which it usually works), by embedding it into another event loop
700(e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course 790(e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course
701also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. 791also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets.
702.Sp 792.Sp
703This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with 793This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with
704\&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with 794\&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with
705\&\f(CW\*(C`NOTE_EOF\*(C'\fR. 795\&\f(CW\*(C`NOTE_EOF\*(C'\fR.
706.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 796.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
710implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets 800implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets
711and is not embeddable, which would limit the usefulness of this backend 801and is not embeddable, which would limit the usefulness of this backend
712immensely. 802immensely.
713.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 803.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
714.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 804.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
715.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 805.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
716This uses the Solaris 10 event port mechanism. As with everything on Solaris, 806This uses the Solaris 10 event port mechanism. As with everything on Solaris,
717it's really slow, but it still scales very well (O(active_fds)). 807it's really slow, but it still scales very well (O(active_fds)).
718.Sp 808.Sp
719While this backend scales well, it requires one system call per active 809While this backend scales well, it requires one system call per active
720file descriptor per loop iteration. For small and medium numbers of file 810file descriptor per loop iteration. For small and medium numbers of file
774used if available. 864used if available.
775.Sp 865.Sp
776.Vb 1 866.Vb 1
777\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); 867\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
778.Ve 868.Ve
869.Sp
870Example: Similarly, on linux, you mgiht want to take advantage of the
871linux aio backend if possible, but fall back to something else if that
872isn't available.
873.Sp
874.Vb 1
875\& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO);
876.Ve
779.RE 877.RE
780.IP "ev_loop_destroy (loop)" 4 878.IP "ev_loop_destroy (loop)" 4
781.IX Item "ev_loop_destroy (loop)" 879.IX Item "ev_loop_destroy (loop)"
782Destroys an event loop object (frees all memory and kernel state 880Destroys an event loop object (frees all memory and kernel state
783etc.). None of the active event watchers will be stopped in the normal 881etc.). None of the active event watchers will be stopped in the normal
799except in the rare occasion where you really need to free its resources. 897except in the rare occasion where you really need to free its resources.
800If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR 898If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR
801and \f(CW\*(C`ev_loop_destroy\*(C'\fR. 899and \f(CW\*(C`ev_loop_destroy\*(C'\fR.
802.IP "ev_loop_fork (loop)" 4 900.IP "ev_loop_fork (loop)" 4
803.IX Item "ev_loop_fork (loop)" 901.IX Item "ev_loop_fork (loop)"
804This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to 902This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations
805reinitialise the kernel state for backends that have one. Despite the 903to reinitialise the kernel state for backends that have one. Despite
806name, you can call it anytime, but it makes most sense after forking, in 904the name, you can call it anytime you are allowed to start or stop
807the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the 905watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most
808child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. 906sense after forking, in the child process. You \fImust\fR call it (or use
907\&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR.
809.Sp 908.Sp
909In addition, if you want to reuse a loop (via this function or
910\&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR.
911.Sp
810Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after 912Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after
811a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is 913a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is
812because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things 914because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things
813during fork. 915during fork.
814.Sp 916.Sp
815On the other hand, you only need to call this function in the child 917On the other hand, you only need to call this function in the child
1349bug in your program. 1451bug in your program.
1350.Sp 1452.Sp
1351Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for 1453Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for
1352example it might indicate that a fd is readable or writable, and if your 1454example it might indicate that a fd is readable or writable, and if your
1353callbacks is well-written it can just attempt the operation and cope with 1455callbacks is well-written it can just attempt the operation and cope with
1354the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded 1456the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded
1355programs, though, as the fd could already be closed and reused for another 1457programs, though, as the fd could already be closed and reused for another
1356thing, so beware. 1458thing, so beware.
1357.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1459.SS "\s-1GENERIC WATCHER FUNCTIONS\s0"
1358.IX Subsection "GENERIC WATCHER FUNCTIONS" 1460.IX Subsection "GENERIC WATCHER FUNCTIONS"
1359.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1461.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1360.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1462.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1361.IX Item "ev_init (ev_TYPE *watcher, callback)" 1463.IX Item "ev_init (ev_TYPE *watcher, callback)"
1362This macro initialises the generic portion of a watcher. The contents 1464This macro initialises the generic portion of a watcher. The contents
1470or might not have been clamped to the valid range. 1572or might not have been clamped to the valid range.
1471.Sp 1573.Sp
1472The default priority used by watchers when no priority has been set is 1574The default priority used by watchers when no priority has been set is
1473always \f(CW0\fR, which is supposed to not be too high and not be too low :). 1575always \f(CW0\fR, which is supposed to not be too high and not be too low :).
1474.Sp 1576.Sp
1475See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of 1577See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of
1476priorities. 1578priorities.
1477.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 1579.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
1478.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" 1580.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
1479Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither 1581Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
1480\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback 1582\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
1500not started in the first place. 1602not started in the first place.
1501.Sp 1603.Sp
1502See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related 1604See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related
1503functions that do not need a watcher. 1605functions that do not need a watcher.
1504.PP 1606.PP
1505See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 1607See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR
1506\&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. 1608OWN COMPOSITE WATCHERS\*(R"\s0 idioms.
1507.SS "\s-1WATCHER\s0 \s-1STATES\s0" 1609.SS "\s-1WATCHER STATES\s0"
1508.IX Subsection "WATCHER STATES" 1610.IX Subsection "WATCHER STATES"
1509There are various watcher states mentioned throughout this manual \- 1611There are various watcher states mentioned throughout this manual \-
1510active, pending and so on. In this section these states and the rules to 1612active, pending and so on. In this section these states and the rules to
1511transition between them will be described in more detail \- and while these 1613transition between them will be described in more detail \- and while these
1512rules might look complicated, they usually do \*(L"the right thing\*(R". 1614rules might look complicated, they usually do \*(L"the right thing\*(R".
1513.IP "initialiased" 4 1615.IP "initialised" 4
1514.IX Item "initialiased" 1616.IX Item "initialised"
1515Before a watcher can be registered with the event loop it has to be 1617Before a watcher can be registered with the event loop it has to be
1516initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to 1618initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to
1517\&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. 1619\&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function.
1518.Sp 1620.Sp
1519In this state it is simply some block of memory that is suitable for 1621In this state it is simply some block of memory that is suitable for
1555.Sp 1657.Sp
1556While stopped (and not pending) the watcher is essentially in the 1658While stopped (and not pending) the watcher is essentially in the
1557initialised state, that is, it can be reused, moved, modified in any way 1659initialised state, that is, it can be reused, moved, modified in any way
1558you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR 1660you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR
1559it again). 1661it again).
1560.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1662.SS "\s-1WATCHER PRIORITY MODELS\s0"
1561.IX Subsection "WATCHER PRIORITY MODELS" 1663.IX Subsection "WATCHER PRIORITY MODELS"
1562Many event loops support \fIwatcher priorities\fR, which are usually small 1664Many event loops support \fIwatcher priorities\fR, which are usually small
1563integers that influence the ordering of event callback invocation 1665integers that influence the ordering of event callback invocation
1564between watchers in some way, all else being equal. 1666between watchers in some way, all else being equal.
1565.PP 1667.PP
1566In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its 1668In libev, watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its
1567description for the more technical details such as the actual priority 1669description for the more technical details such as the actual priority
1568range. 1670range.
1569.PP 1671.PP
1570There are two common ways how these these priorities are being interpreted 1672There are two common ways how these these priorities are being interpreted
1571by event loops: 1673by event loops:
1665.IX Header "WATCHER TYPES" 1767.IX Header "WATCHER TYPES"
1666This section describes each watcher in detail, but will not repeat 1768This section describes each watcher in detail, but will not repeat
1667information given in the last section. Any initialisation/set macros, 1769information given in the last section. Any initialisation/set macros,
1668functions and members specific to the watcher type are explained. 1770functions and members specific to the watcher type are explained.
1669.PP 1771.PP
1670Members are additionally marked with either \fI[read\-only]\fR, meaning that, 1772Most members are additionally marked with either \fI[read\-only]\fR, meaning
1671while the watcher is active, you can look at the member and expect some 1773that, while the watcher is active, you can look at the member and expect
1672sensible content, but you must not modify it (you can modify it while the 1774some sensible content, but you must not modify it (you can modify it while
1673watcher is stopped to your hearts content), or \fI[read\-write]\fR, which 1775the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
1674means you can expect it to have some sensible content while the watcher 1776means you can expect it to have some sensible content while the watcher
1675is active, but you can also modify it. Modifying it may not do something 1777is active, but you can also modify it. Modifying it may not do something
1676sensible or take immediate effect (or do anything at all), but libev will 1778sensible or take immediate effect (or do anything at all), but libev will
1677not crash or malfunction in any way. 1779not crash or malfunction in any way.
1780.PP
1781In any case, the documentation for each member will explain what the
1782effects are, and if there are any additional access restrictions.
1678.ie n .SS """ev_io"" \- is this file descriptor readable or writable?" 1783.ie n .SS """ev_io"" \- is this file descriptor readable or writable?"
1679.el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" 1784.el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?"
1680.IX Subsection "ev_io - is this file descriptor readable or writable?" 1785.IX Subsection "ev_io - is this file descriptor readable or writable?"
1681I/O watchers check whether a file descriptor is readable or writable 1786I/O watchers check whether a file descriptor is readable or writable
1682in each iteration of the event loop, or, more precisely, when reading 1787in each iteration of the event loop, or, more precisely, when reading
1710But really, best use non-blocking mode. 1815But really, best use non-blocking mode.
1711.PP 1816.PP
1712\fIThe special problem of disappearing file descriptors\fR 1817\fIThe special problem of disappearing file descriptors\fR
1713.IX Subsection "The special problem of disappearing file descriptors" 1818.IX Subsection "The special problem of disappearing file descriptors"
1714.PP 1819.PP
1715Some backends (e.g. kqueue, epoll) need to be told about closing a file 1820Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing
1716descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, 1821a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other
1717such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file 1822means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some
1718descriptor, but when it goes away, the operating system will silently drop 1823file descriptor, but when it goes away, the operating system will silently
1719this interest. If another file descriptor with the same number then is 1824drop this interest. If another file descriptor with the same number then
1720registered with libev, there is no efficient way to see that this is, in 1825is registered with libev, there is no efficient way to see that this is,
1721fact, a different file descriptor. 1826in fact, a different file descriptor.
1722.PP 1827.PP
1723To avoid having to explicitly tell libev about such cases, libev follows 1828To avoid having to explicitly tell libev about such cases, libev follows
1724the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev 1829the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1725will assume that this is potentially a new file descriptor, otherwise 1830will assume that this is potentially a new file descriptor, otherwise
1726it is assumed that the file descriptor stays the same. That means that 1831it is assumed that the file descriptor stays the same. That means that
1763wish to read \- you would first have to request some data. 1868wish to read \- you would first have to request some data.
1764.PP 1869.PP
1765Since files are typically not-so-well supported by advanced notification 1870Since files are typically not-so-well supported by advanced notification
1766mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect 1871mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect
1767to files, even though you should not use it. The reason for this is 1872to files, even though you should not use it. The reason for this is
1768convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is 1873convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is
1769usually a tty, often a pipe, but also sometimes files or special devices 1874usually a tty, often a pipe, but also sometimes files or special devices
1770(for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with 1875(for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with
1771\&\fI/dev/urandom\fR), and even though the file might better be served with 1876\&\fI/dev/urandom\fR), and even though the file might better be served with
1772asynchronous I/O instead of with non-blocking I/O, it is still useful when 1877asynchronous I/O instead of with non-blocking I/O, it is still useful when
1773it \*(L"just works\*(R" instead of freezing. 1878it \*(L"just works\*(R" instead of freezing.
1774.PP 1879.PP
1775So avoid file descriptors pointing to files when you know it (e.g. use 1880So avoid file descriptors pointing to files when you know it (e.g. use
1776libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or 1881libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or
1777when you rarely read from a file instead of from a socket, and want to 1882when you rarely read from a file instead of from a socket, and want to
1778reuse the same code path. 1883reuse the same code path.
1779.PP 1884.PP
1780\fIThe special problem of fork\fR 1885\fIThe special problem of fork\fR
1781.IX Subsection "The special problem of fork" 1886.IX Subsection "The special problem of fork"
1782.PP 1887.PP
1783Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit 1888Some backends (epoll, kqueue, linuxaio, iouring) do not support \f(CW\*(C`fork ()\*(C'\fR
1784useless behaviour. Libev fully supports fork, but needs to be told about 1889at all or exhibit useless behaviour. Libev fully supports fork, but needs
1785it in the child if you want to continue to use it in the child. 1890to be told about it in the child if you want to continue to use it in the
1891child.
1786.PP 1892.PP
1787To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork 1893To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork
1788()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to 1894()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to
1789\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. 1895\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1790.PP 1896.PP
1791\fIThe special problem of \s-1SIGPIPE\s0\fR 1897\fIThe special problem of \s-1SIGPIPE\s0\fR
1792.IX Subsection "The special problem of SIGPIPE" 1898.IX Subsection "The special problem of SIGPIPE"
1793.PP 1899.PP
1794While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: 1900While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR:
1795when writing to a pipe whose other end has been closed, your program gets 1901when writing to a pipe whose other end has been closed, your program gets
1796sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs 1902sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs
1797this is sensible behaviour, for daemons, this is usually undesirable. 1903this is sensible behaviour, for daemons, this is usually undesirable.
1798.PP 1904.PP
1799So when you encounter spurious, unexplained daemon exits, make sure you 1905So when you encounter spurious, unexplained daemon exits, make sure you
1800ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon 1906ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon
1801somewhere, as that would have given you a big clue). 1907somewhere, as that would have given you a big clue).
1802.PP 1908.PP
1803\fIThe special problem of \fIaccept()\fIing when you can't\fR 1909\fIThe special problem of \f(BIaccept()\fIing when you can't\fR
1804.IX Subsection "The special problem of accept()ing when you can't" 1910.IX Subsection "The special problem of accept()ing when you can't"
1805.PP 1911.PP
1806Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, 1912Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example,
1807found in post\-2004 Linux) have the peculiar behaviour of not removing a 1913found in post\-2004 Linux) have the peculiar behaviour of not removing a
1808connection from the pending queue in all error cases. 1914connection from the pending queue in all error cases.
1849.IX Item "ev_io_set (ev_io *, int fd, int events)" 1955.IX Item "ev_io_set (ev_io *, int fd, int events)"
1850.PD 1956.PD
1851Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to 1957Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
1852receive 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 1958receive 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
1853\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. 1959\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events.
1960.IP "ev_io_modify (ev_io *, int events)" 4
1961.IX Item "ev_io_modify (ev_io *, int events)"
1962Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the event mask. Using this might
1963be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR still
1964refers to the same underlying file description, something it cannot do
1965when using \f(CW\*(C`ev_io_set\*(C'\fR.
1854.IP "int fd [read\-only]" 4 1966.IP "int fd [no\-modify]" 4
1855.IX Item "int fd [read-only]" 1967.IX Item "int fd [no-modify]"
1856The file descriptor being watched. 1968The file descriptor being watched. While it can be read at any time, you
1969must not modify this member even when the watcher is stopped \- always use
1970\&\f(CW\*(C`ev_io_set\*(C'\fR for that.
1857.IP "int events [read\-only]" 4 1971.IP "int events [no\-modify]" 4
1858.IX Item "int events [read-only]" 1972.IX Item "int events [no-modify]"
1859The events being watched. 1973The set of events being watched, among other flags. This field is a
1974bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events & EV_READ\*(C'\fR, and
1975similarly for \f(CW\*(C`EV_WRITE\*(C'\fR.
1976.Sp
1977As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is
1978stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that.
1860.PP 1979.PP
1861\fIExamples\fR 1980\fIExamples\fR
1862.IX Subsection "Examples" 1981.IX Subsection "Examples"
1863.PP 1982.PP
1864Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1983Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
2150.PP 2269.PP
2151The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR 2270The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR
2152time. This is usually the right thing as this timestamp refers to the time 2271time. This is usually the right thing as this timestamp refers to the time
2153of the event triggering whatever timeout you are modifying/starting. If 2272of the event triggering whatever timeout you are modifying/starting. If
2154you suspect event processing to be delayed and you \fIneed\fR to base the 2273you suspect event processing to be delayed and you \fIneed\fR to base the
2155timeout on the current time, use something like this to adjust for this: 2274timeout on the current time, use something like the following to adjust
2275for it:
2156.PP 2276.PP
2157.Vb 1 2277.Vb 1
2158\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); 2278\& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.);
2159.Ve 2279.Ve
2160.PP 2280.PP
2161If the event loop is suspended for a long time, you can also force an 2281If the event loop is suspended for a long time, you can also force an
2162update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update 2282update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update
2163()\*(C'\fR. 2283()\*(C'\fR, although that will push the event time of all outstanding events
2284further into the future.
2164.PP 2285.PP
2165\fIThe special problem of unsynchronised clocks\fR 2286\fIThe special problem of unsynchronised clocks\fR
2166.IX Subsection "The special problem of unsynchronised clocks" 2287.IX Subsection "The special problem of unsynchronised clocks"
2167.PP 2288.PP
2168Modern systems have a variety of clocks \- libev itself uses the normal 2289Modern systems have a variety of clocks \- libev itself uses the normal
2233.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 2354.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
2234.PD 0 2355.PD 0
2235.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 2356.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
2236.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 2357.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
2237.PD 2358.PD
2238Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR 2359Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and
2239is \f(CW0.\fR, then it will automatically be stopped once the timeout is 2360negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will
2240reached. If it is positive, then the timer will automatically be 2361automatically be stopped once the timeout is reached. If it is positive,
2241configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, 2362then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR
2242until stopped manually. 2363seconds later, again, and again, until stopped manually.
2243.Sp 2364.Sp
2244The timer itself will do a best-effort at avoiding drift, that is, if 2365The timer itself will do a best-effort at avoiding drift, that is, if
2245you configure a timer to trigger every 10 seconds, then it will normally 2366you configure a timer to trigger every 10 seconds, then it will normally
2246trigger at exactly 10 second intervals. If, however, your program cannot 2367trigger at exactly 10 second intervals. If, however, your program cannot
2247keep up with the timer (because it takes longer than those 10 seconds to 2368keep up with the timer (because it takes longer than those 10 seconds to
2329Periodic watchers are also timers of a kind, but they are very versatile 2450Periodic watchers are also timers of a kind, but they are very versatile
2330(and unfortunately a bit complex). 2451(and unfortunately a bit complex).
2331.PP 2452.PP
2332Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or 2453Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or
2333relative time, the physical time that passes) but on wall clock time 2454relative time, the physical time that passes) but on wall clock time
2334(absolute time, the thing you can read on your calender or clock). The 2455(absolute time, the thing you can read on your calendar or clock). The
2335difference is that wall clock time can run faster or slower than real 2456difference is that wall clock time can run faster or slower than real
2336time, and time jumps are not uncommon (e.g. when you adjust your 2457time, and time jumps are not uncommon (e.g. when you adjust your
2337wrist-watch). 2458wrist-watch).
2338.PP 2459.PP
2339You can tell a periodic watcher to trigger after some specific point 2460You can tell a periodic watcher to trigger after some specific point
2344\&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting 2465\&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting
2345it, as it uses a relative timeout). 2466it, as it uses a relative timeout).
2346.PP 2467.PP
2347\&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex 2468\&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex
2348timers, such as triggering an event on each \*(L"midnight, local time\*(R", or 2469timers, such as triggering an event on each \*(L"midnight, local time\*(R", or
2349other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as 2470other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR
2350those cannot react to time jumps. 2471watchers, as those cannot react to time jumps.
2351.PP 2472.PP
2352As with timers, the callback is guaranteed to be invoked only when the 2473As with timers, the callback is guaranteed to be invoked only when the
2353point in time where it is supposed to trigger has passed. If multiple 2474point in time where it is supposed to trigger has passed. If multiple
2354timers become ready during the same loop iteration then the ones with 2475timers become ready during the same loop iteration then the ones with
2355earlier time-out values are invoked before ones with later time-out values 2476earlier time-out values are invoked before ones with later time-out values
2416In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being 2537In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being
2417ignored. Instead, each time the periodic watcher gets scheduled, the 2538ignored. Instead, each time the periodic watcher gets scheduled, the
2418reschedule callback will be called with the watcher as first, and the 2539reschedule callback will be called with the watcher as first, and the
2419current time as second argument. 2540current time as second argument.
2420.Sp 2541.Sp
2421\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, 2542\&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever,
2422or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly 2543or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly
2423allowed by documentation here\fR. 2544allowed by documentation here\fR.
2424.Sp 2545.Sp
2425If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop 2546If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop
2426it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the 2547it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the
2444.Sp 2565.Sp
2445\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or 2566\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or
2446equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. 2567equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
2447.Sp 2568.Sp
2448This can be used to create very complex timers, such as a timer that 2569This can be used to create very complex timers, such as a timer that
2449triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the 2570triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate
2450next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How 2571the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for
2451you do this is, again, up to you (but it is not trivial, which is the main 2572this. Here is a (completely untested, no error checking) example on how to
2452reason I omitted it as an example). 2573do this:
2574.Sp
2575.Vb 1
2576\& #include <time.h>
2577\&
2578\& static ev_tstamp
2579\& my_rescheduler (ev_periodic *w, ev_tstamp now)
2580\& {
2581\& time_t tnow = (time_t)now;
2582\& struct tm tm;
2583\& localtime_r (&tnow, &tm);
2584\&
2585\& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day
2586\& ++tm.tm_mday; // midnight next day
2587\&
2588\& return mktime (&tm);
2589\& }
2590.Ve
2591.Sp
2592Note: this code might run into trouble on days that have more then two
2593midnights (beginning and end).
2453.RE 2594.RE
2454.RS 4 2595.RS 4
2455.RE 2596.RE
2456.IP "ev_periodic_again (loop, ev_periodic *)" 4 2597.IP "ev_periodic_again (loop, ev_periodic *)" 4
2457.IX Item "ev_periodic_again (loop, ev_periodic *)" 2598.IX Item "ev_periodic_again (loop, ev_periodic *)"
2542only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your 2683only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your
2543default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for 2684default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for
2544\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At 2685\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At
2545the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. 2686the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop.
2546.PP 2687.PP
2547When the first watcher gets started will libev actually register something 2688Only after the first watcher for a signal is started will libev actually
2548with the kernel (thus it coexists with your own signal handlers as long as 2689register something with the kernel. It thus coexists with your own signal
2549you don't register any with libev for the same signal). 2690handlers as long as you don't register any with libev for the same signal.
2550.PP 2691.PP
2551If possible and supported, libev will install its handlers with 2692If possible and supported, libev will install its handlers with
2552\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should 2693\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should
2553not be unduly interrupted. If you have a problem with system calls getting 2694not be unduly interrupted. If you have a problem with system calls getting
2554interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher 2695interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher
2615The signal the watcher watches out for. 2756The signal the watcher watches out for.
2616.PP 2757.PP
2617\fIExamples\fR 2758\fIExamples\fR
2618.IX Subsection "Examples" 2759.IX Subsection "Examples"
2619.PP 2760.PP
2620Example: Try to exit cleanly on \s-1SIGINT\s0. 2761Example: Try to exit cleanly on \s-1SIGINT.\s0
2621.PP 2762.PP
2622.Vb 5 2763.Vb 5
2623\& static void 2764\& static void
2624\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) 2765\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2625\& { 2766\& {
2740.ie n .SS """ev_stat"" \- did the file attributes just change?" 2881.ie n .SS """ev_stat"" \- did the file attributes just change?"
2741.el .SS "\f(CWev_stat\fP \- did the file attributes just change?" 2882.el .SS "\f(CWev_stat\fP \- did the file attributes just change?"
2742.IX Subsection "ev_stat - did the file attributes just change?" 2883.IX Subsection "ev_stat - did the file attributes just change?"
2743This watches a file system path for attribute changes. That is, it calls 2884This watches a file system path for attribute changes. That is, it calls
2744\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) 2885\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed)
2745and sees if it changed compared to the last time, invoking the callback if 2886and sees if it changed compared to the last time, invoking the callback
2746it did. 2887if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that
2888happen after the watcher has been started will be reported.
2747.PP 2889.PP
2748The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does 2890The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
2749not exist\*(R" is a status change like any other. The condition \*(L"path does not 2891not exist\*(R" is a status change like any other. The condition \*(L"path does not
2750exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the 2892exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the
2751\&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at 2893\&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at
2781compilation environment, which means that on systems with large file 2923compilation environment, which means that on systems with large file
2782support disabled by default, you get the 32 bit version of the stat 2924support disabled by default, you get the 32 bit version of the stat
2783structure. When using the library from programs that change the \s-1ABI\s0 to 2925structure. When using the library from programs that change the \s-1ABI\s0 to
2784use 64 bit file offsets the programs will fail. In that case you have to 2926use 64 bit file offsets the programs will fail. In that case you have to
2785compile libev with the same flags to get binary compatibility. This is 2927compile libev with the same flags to get binary compatibility. This is
2786obviously the case with any flags that change the \s-1ABI\s0, but the problem is 2928obviously the case with any flags that change the \s-1ABI,\s0 but the problem is
2787most noticeably displayed with ev_stat and large file support. 2929most noticeably displayed with ev_stat and large file support.
2788.PP 2930.PP
2789The solution for this is to lobby your distribution maker to make large 2931The solution for this is to lobby your distribution maker to make large
2790file interfaces available by default (as e.g. FreeBSD does) and not 2932file interfaces available by default (as e.g. FreeBSD does) and not
2791optional. Libev cannot simply switch on large file support because it has 2933optional. Libev cannot simply switch on large file support because it has
3036.IX Subsection "ev_prepare and ev_check - customise your event loop!" 3178.IX Subsection "ev_prepare and ev_check - customise your event loop!"
3037Prepare and check watchers are often (but not always) used in pairs: 3179Prepare and check watchers are often (but not always) used in pairs:
3038prepare watchers get invoked before the process blocks and check watchers 3180prepare watchers get invoked before the process blocks and check watchers
3039afterwards. 3181afterwards.
3040.PP 3182.PP
3041You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter 3183You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the
3042the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR 3184current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or
3043watchers. Other loops than the current one are fine, however. The 3185\&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine,
3044rationale behind this is that you do not need to check for recursion in 3186however. The rationale behind this is that you do not need to check
3045those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, 3187for recursion in those watchers, i.e. the sequence will always be
3046\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be 3188\&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each
3047called in pairs bracketing the blocking call. 3189kind they will always be called in pairs bracketing the blocking call.
3048.PP 3190.PP
3049Their main purpose is to integrate other event mechanisms into libev and 3191Their main purpose is to integrate other event mechanisms into libev and
3050their use is somewhat advanced. They could be used, for example, to track 3192their use is somewhat advanced. They could be used, for example, to track
3051variable changes, implement your own watchers, integrate net-snmp or a 3193variable changes, implement your own watchers, integrate net-snmp or a
3052coroutine library and lots more. They are also occasionally useful if 3194coroutine library and lots more. They are also occasionally useful if
3222.Ve 3364.Ve
3223.PP 3365.PP
3224Method 4: Do not use a prepare or check watcher because the module you 3366Method 4: Do not use a prepare or check watcher because the module you
3225want to embed is not flexible enough to support it. Instead, you can 3367want to embed is not flexible enough to support it. Instead, you can
3226override their poll function. The drawback with this solution is that the 3368override their poll function. The drawback with this solution is that the
3227main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses 3369main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses
3228this approach, effectively embedding \s-1EV\s0 as a client into the horrible 3370this approach, effectively embedding \s-1EV\s0 as a client into the horrible
3229libglib event loop. 3371libglib event loop.
3230.PP 3372.PP
3231.Vb 4 3373.Vb 4
3232\& static gint 3374\& static gint
3316\fIWatcher-Specific Functions and Data Members\fR 3458\fIWatcher-Specific Functions and Data Members\fR
3317.IX Subsection "Watcher-Specific Functions and Data Members" 3459.IX Subsection "Watcher-Specific Functions and Data Members"
3318.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 3460.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
3319.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 3461.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
3320.PD 0 3462.PD 0
3321.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 3463.IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4
3322.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 3464.IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)"
3323.PD 3465.PD
3324Configures the watcher to embed the given loop, which must be 3466Configures the watcher to embed the given loop, which must be
3325embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be 3467embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
3326invoked automatically, otherwise it is the responsibility of the callback 3468invoked automatically, otherwise it is the responsibility of the callback
3327to invoke it (it will continue to be called until the sweep has been done, 3469to invoke it (it will continue to be called until the sweep has been done,
3346.PP 3488.PP
3347.Vb 3 3489.Vb 3
3348\& struct ev_loop *loop_hi = ev_default_init (0); 3490\& struct ev_loop *loop_hi = ev_default_init (0);
3349\& struct ev_loop *loop_lo = 0; 3491\& struct ev_loop *loop_lo = 0;
3350\& ev_embed embed; 3492\& ev_embed embed;
3351\& 3493\&
3352\& // see if there is a chance of getting one that works 3494\& // see if there is a chance of getting one that works
3353\& // (remember that a flags value of 0 means autodetection) 3495\& // (remember that a flags value of 0 means autodetection)
3354\& loop_lo = ev_embeddable_backends () & ev_recommended_backends () 3496\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
3355\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) 3497\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
3356\& : 0; 3498\& : 0;
3372.PP 3514.PP
3373.Vb 3 3515.Vb 3
3374\& struct ev_loop *loop = ev_default_init (0); 3516\& struct ev_loop *loop = ev_default_init (0);
3375\& struct ev_loop *loop_socket = 0; 3517\& struct ev_loop *loop_socket = 0;
3376\& ev_embed embed; 3518\& ev_embed embed;
3377\& 3519\&
3378\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) 3520\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
3379\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) 3521\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
3380\& { 3522\& {
3381\& ev_embed_init (&embed, 0, loop_socket); 3523\& ev_embed_init (&embed, 0, loop_socket);
3382\& ev_embed_start (loop, &embed); 3524\& ev_embed_start (loop, &embed);
3390.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" 3532.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork"
3391.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 3533.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
3392.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 3534.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
3393Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 3535Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
3394whoever is a good citizen cared to tell libev about it by calling 3536whoever is a good citizen cared to tell libev about it by calling
3395\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 3537\&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next
3396event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 3538and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child
3397and only in the child after the fork. If whoever good citizen calling 3539after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats
3398\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 3540and calls it in the wrong process, the fork handlers will be invoked, too,
3399handlers will be invoked, too, of course. 3541of course.
3400.PP 3542.PP
3401\fIThe special problem of life after fork \- how is it possible?\fR 3543\fIThe special problem of life after fork \- how is it possible?\fR
3402.IX Subsection "The special problem of life after fork - how is it possible?" 3544.IX Subsection "The special problem of life after fork - how is it possible?"
3403.PP 3545.PP
3404Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set 3546Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set
3405up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This 3547up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This
3406sequence should be handled by libev without any problems. 3548sequence should be handled by libev without any problems.
3407.PP 3549.PP
3408This changes when the application actually wants to do event handling 3550This changes when the application actually wants to do event handling
3409in the child, or both parent in child, in effect \*(L"continuing\*(R" after the 3551in the child, or both parent in child, in effect \*(L"continuing\*(R" after the
3626is a time window between the event loop checking and resetting the async 3768is a time window between the event loop checking and resetting the async
3627notification, and the callback being invoked. 3769notification, and the callback being invoked.
3628.SH "OTHER FUNCTIONS" 3770.SH "OTHER FUNCTIONS"
3629.IX Header "OTHER FUNCTIONS" 3771.IX Header "OTHER FUNCTIONS"
3630There are some other functions of possible interest. Described. Here. Now. 3772There are some other functions of possible interest. Described. Here. Now.
3631.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 3773.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4
3632.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 3774.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)"
3633This function combines a simple timer and an I/O watcher, calls your 3775This function combines a simple timer and an I/O watcher, calls your
3634callback on whichever event happens first and automatically stops both 3776callback on whichever event happens first and automatically stops both
3635watchers. This is useful if you want to wait for a single event on an fd 3777watchers. This is useful if you want to wait for a single event on an fd
3636or timeout without having to allocate/configure/start/stop/free one or 3778or timeout without having to allocate/configure/start/stop/free one or
3637more watchers yourself. 3779more watchers yourself.
3649\&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR 3791\&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR
3650value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR 3792value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR
3651a timeout and an io event at the same time \- you probably should give io 3793a timeout and an io event at the same time \- you probably should give io
3652events precedence. 3794events precedence.
3653.Sp 3795.Sp
3654Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. 3796Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0
3655.Sp 3797.Sp
3656.Vb 7 3798.Vb 7
3657\& static void stdin_ready (int revents, void *arg) 3799\& static void stdin_ready (int revents, void *arg)
3658\& { 3800\& {
3659\& if (revents & EV_READ) 3801\& if (revents & EV_READ)
3675.SH "COMMON OR USEFUL IDIOMS (OR BOTH)" 3817.SH "COMMON OR USEFUL IDIOMS (OR BOTH)"
3676.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" 3818.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)"
3677This section explains some common idioms that are not immediately 3819This section explains some common idioms that are not immediately
3678obvious. Note that examples are sprinkled over the whole manual, and this 3820obvious. Note that examples are sprinkled over the whole manual, and this
3679section only contains stuff that wouldn't fit anywhere else. 3821section only contains stuff that wouldn't fit anywhere else.
3680.SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 3822.SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0"
3681.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 3823.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
3682Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read 3824Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read
3683or modify at any time: libev will completely ignore it. This can be used 3825or modify at any time: libev will completely ignore it. This can be used
3684to associate arbitrary data with your watcher. If you need more data and 3826to associate arbitrary data with your watcher. If you need more data and
3685don't want to allocate memory separately and store a pointer to it in that 3827don't want to allocate memory separately and store a pointer to it in that
3711\& } 3853\& }
3712.Ve 3854.Ve
3713.PP 3855.PP
3714More interesting and less C\-conformant ways of casting your callback 3856More interesting and less C\-conformant ways of casting your callback
3715function type instead have been omitted. 3857function type instead have been omitted.
3716.SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" 3858.SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0"
3717.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" 3859.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS"
3718Another common scenario is to use some data structure with multiple 3860Another common scenario is to use some data structure with multiple
3719embedded watchers, in effect creating your own watcher that combines 3861embedded watchers, in effect creating your own watcher that combines
3720multiple libev event sources into one \*(L"super-watcher\*(R": 3862multiple libev event sources into one \*(L"super-watcher\*(R":
3721.PP 3863.PP
3749\& { 3891\& {
3750\& struct my_biggy big = (struct my_biggy *) 3892\& struct my_biggy big = (struct my_biggy *)
3751\& (((char *)w) \- offsetof (struct my_biggy, t2)); 3893\& (((char *)w) \- offsetof (struct my_biggy, t2));
3752\& } 3894\& }
3753.Ve 3895.Ve
3754.SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" 3896.SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0"
3755.IX Subsection "AVOIDING FINISHING BEFORE RETURNING" 3897.IX Subsection "AVOIDING FINISHING BEFORE RETURNING"
3756Often you have structures like this in event-based programs: 3898Often you have structures like this in event-based programs:
3757.PP 3899.PP
3758.Vb 4 3900.Vb 4
3759\& callback () 3901\& callback ()
3781already been invoked. 3923already been invoked.
3782.PP 3924.PP
3783A common way around all these issues is to make sure that 3925A common way around all these issues is to make sure that
3784\&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If 3926\&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If
3785\&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially 3927\&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially
3786delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher 3928delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for
3787for example, or more sneakily, by reusing an existing (stopped) watcher 3929example, or more sneakily, by reusing an existing (stopped) watcher and
3788and pushing it into the pending queue: 3930pushing it into the pending queue:
3789.PP 3931.PP
3790.Vb 2 3932.Vb 2
3791\& ev_set_cb (watcher, callback); 3933\& ev_set_cb (watcher, callback);
3792\& ev_feed_event (EV_A_ watcher, 0); 3934\& ev_feed_event (EV_A_ watcher, 0);
3793.Ve 3935.Ve
3794.PP 3936.PP
3795This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is 3937This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is
3796invoked, while not delaying callback invocation too much. 3938invoked, while not delaying callback invocation too much.
3797.SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" 3939.SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0"
3798.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" 3940.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS"
3799Often (especially in \s-1GUI\s0 toolkits) there are places where you have 3941Often (especially in \s-1GUI\s0 toolkits) there are places where you have
3800\&\fImodal\fR interaction, which is most easily implemented by recursively 3942\&\fImodal\fR interaction, which is most easily implemented by recursively
3801invoking \f(CW\*(C`ev_run\*(C'\fR. 3943invoking \f(CW\*(C`ev_run\*(C'\fR.
3802.PP 3944.PP
3803This brings the problem of exiting \- a callback might want to finish the 3945This brings the problem of exiting \- a callback might want to finish the
3804main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but 3946main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but
3805a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one 3947a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one
3806and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some 3948and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some
3807other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. 3949other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work.
3808.PP 3950.PP
3809The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR 3951The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR
3810invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is 3952invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is
3811triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: 3953triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR:
3812.PP 3954.PP
3834\& exit_main_loop = 1; 3976\& exit_main_loop = 1;
3835\& 3977\&
3836\& // exit both 3978\& // exit both
3837\& exit_main_loop = exit_nested_loop = 1; 3979\& exit_main_loop = exit_nested_loop = 1;
3838.Ve 3980.Ve
3839.SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" 3981.SS "\s-1THREAD LOCKING EXAMPLE\s0"
3840.IX Subsection "THREAD LOCKING EXAMPLE" 3982.IX Subsection "THREAD LOCKING EXAMPLE"
3841Here is a fictitious example of how to run an event loop in a different 3983Here is a fictitious example of how to run an event loop in a different
3842thread from where callbacks are being invoked and watchers are 3984thread from where callbacks are being invoked and watchers are
3843created/added/removed. 3985created/added/removed.
3844.PP 3986.PP
3985.PP 4127.PP
3986Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise 4128Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
3987an event loop currently blocking in the kernel will have no knowledge 4129an event loop currently blocking in the kernel will have no knowledge
3988about the newly added timer. By waking up the loop it will pick up any new 4130about the newly added timer. By waking up the loop it will pick up any new
3989watchers in the next event loop iteration. 4131watchers in the next event loop iteration.
3990.SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" 4132.SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0"
3991.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" 4133.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS"
3992While the overhead of a callback that e.g. schedules a thread is small, it 4134While the overhead of a callback that e.g. schedules a thread is small, it
3993is still an overhead. If you embed libev, and your main usage is with some 4135is still an overhead. If you embed libev, and your main usage is with some
3994kind of threads or coroutines, you might want to customise libev so that 4136kind of threads or coroutines, you might want to customise libev so that
3995doesn't need callbacks anymore. 4137doesn't need callbacks anymore.
4031You can do similar tricks if you have, say, threads with an event queue \- 4173You can do similar tricks if you have, say, threads with an event queue \-
4032instead of storing a coroutine, you store the queue object and instead of 4174instead of storing a coroutine, you store the queue object and instead of
4033switching to a coroutine, you push the watcher onto the queue and notify 4175switching to a coroutine, you push the watcher onto the queue and notify
4034any waiters. 4176any waiters.
4035.PP 4177.PP
4036To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two 4178To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two
4037files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: 4179files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files:
4038.PP 4180.PP
4039.Vb 4 4181.Vb 4
4040\& // my_ev.h 4182\& // my_ev.h
4041\& #define EV_CB_DECLARE(type) struct my_coro *cb; 4183\& #define EV_CB_DECLARE(type) struct my_coro *cb;
4042\& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); 4184\& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb)
4043\& #include "../libev/ev.h" 4185\& #include "../libev/ev.h"
4044\& 4186\&
4045\& // my_ev.c 4187\& // my_ev.c
4046\& #define EV_H "my_ev.h" 4188\& #define EV_H "my_ev.h"
4047\& #include "../libev/ev.c" 4189\& #include "../libev/ev.c"
4087The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the 4229The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the
4088libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 4230libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0
4089will work fine. 4231will work fine.
4090.PP 4232.PP
4091Proper exception specifications might have to be added to callbacks passed 4233Proper exception specifications might have to be added to callbacks passed
4092to libev: exceptions may be thrown only from watcher callbacks, all 4234to libev: exceptions may be thrown only from watcher callbacks, all other
4093other callbacks (allocator, syserr, loop acquire/release and periodioc 4235callbacks (allocator, syserr, loop acquire/release and periodic reschedule
4094reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw 4236callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR
4095()\*(C'\fR specification. If you have code that needs to be compiled as both C 4237specification. If you have code that needs to be compiled as both C and
4096and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: 4238\&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this:
4097.PP 4239.PP
4098.Vb 6 4240.Vb 6
4099\& static void 4241\& static void
4100\& fatal_error (const char *msg) EV_THROW 4242\& fatal_error (const char *msg) EV_NOEXCEPT
4101\& { 4243\& {
4102\& perror (msg); 4244\& perror (msg);
4103\& abort (); 4245\& abort ();
4104\& } 4246\& }
4105\& 4247\&
4233\& void operator() (ev::io &w, int revents) 4375\& void operator() (ev::io &w, int revents)
4234\& { 4376\& {
4235\& ... 4377\& ...
4236\& } 4378\& }
4237\& } 4379\& }
4238\& 4380\&
4239\& myfunctor f; 4381\& myfunctor f;
4240\& 4382\&
4241\& ev::io w; 4383\& ev::io w;
4242\& w.set (&f); 4384\& w.set (&f);
4243.Ve 4385.Ve
4261.IX Item "w->set (loop)" 4403.IX Item "w->set (loop)"
4262Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 4404Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
4263do this when the watcher is inactive (and not pending either). 4405do this when the watcher is inactive (and not pending either).
4264.IP "w\->set ([arguments])" 4 4406.IP "w\->set ([arguments])" 4
4265.IX Item "w->set ([arguments])" 4407.IX Item "w->set ([arguments])"
4266Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this 4408Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>),
4267method or a suitable start method must be called at least once. Unlike the 4409with the same arguments. Either this method or a suitable start method
4268C counterpart, an active watcher gets automatically stopped and restarted 4410must be called at least once. Unlike the C counterpart, an active watcher
4269when reconfiguring it with this method. 4411gets automatically stopped and restarted when reconfiguring it with this
4412method.
4413.Sp
4414For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid
4415clashing with the \f(CW\*(C`set (loop)\*(C'\fR method.
4270.IP "w\->start ()" 4 4416.IP "w\->start ()" 4
4271.IX Item "w->start ()" 4417.IX Item "w->start ()"
4272Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the 4418Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
4273constructor already stores the event loop. 4419constructor already stores the event loop.
4274.IP "w\->start ([arguments])" 4 4420.IP "w\->start ([arguments])" 4
4332there are additional modules that implement libev-compatible interfaces 4478there are additional modules that implement libev-compatible interfaces
4333to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), 4479to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays),
4334\&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR 4480\&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR
4335and \f(CW\*(C`EV::Glib\*(C'\fR). 4481and \f(CW\*(C`EV::Glib\*(C'\fR).
4336.Sp 4482.Sp
4337It can be found and installed via \s-1CPAN\s0, its homepage is at 4483It can be found and installed via \s-1CPAN,\s0 its homepage is at
4338<http://software.schmorp.de/pkg/EV>. 4484<http://software.schmorp.de/pkg/EV>.
4339.IP "Python" 4 4485.IP "Python" 4
4340.IX Item "Python" 4486.IX Item "Python"
4341Python bindings can be found at <http://code.google.com/p/pyev/>. It 4487Python bindings can be found at <http://code.google.com/p/pyev/>. It
4342seems to be quite complete and well-documented. 4488seems to be quite complete and well-documented.
4350Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR 4496Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR
4351makes rev work even on mingw. 4497makes rev work even on mingw.
4352.IP "Haskell" 4 4498.IP "Haskell" 4
4353.IX Item "Haskell" 4499.IX Item "Haskell"
4354A haskell binding to libev is available at 4500A haskell binding to libev is available at
4355http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. 4501<http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>.
4356.IP "D" 4 4502.IP "D" 4
4357.IX Item "D" 4503.IX Item "D"
4358Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to 4504Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to
4359be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. 4505be found at <http://www.llucax.com.ar/proj/ev.d/index.html>.
4360.IP "Ocaml" 4 4506.IP "Ocaml" 4
4361.IX Item "Ocaml" 4507.IX Item "Ocaml"
4362Erkki Seppala has written Ocaml bindings for libev, to be found at 4508Erkki Seppala has written Ocaml bindings for libev, to be found at
4363http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. 4509<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>.
4364.IP "Lua" 4 4510.IP "Lua" 4
4365.IX Item "Lua" 4511.IX Item "Lua"
4366Brian Maher has written a partial interface to libev for lua (at the 4512Brian Maher has written a partial interface to libev for lua (at the
4367time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at 4513time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at
4368http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. 4514<http://github.com/brimworks/lua\-ev>.
4515.IP "Javascript" 4
4516.IX Item "Javascript"
4517Node.js (<http://nodejs.org>) uses libev as the underlying event library.
4518.IP "Others" 4
4519.IX Item "Others"
4520There are others, and I stopped counting.
4369.SH "MACRO MAGIC" 4521.SH "MACRO MAGIC"
4370.IX Header "MACRO MAGIC" 4522.IX Header "MACRO MAGIC"
4371Libev can be compiled with a variety of options, the most fundamental 4523Libev can be compiled with a variety of options, the most fundamental
4372of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 4524of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
4373functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 4525functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
4456.SS "\s-1FILESETS\s0" 4608.SS "\s-1FILESETS\s0"
4457.IX Subsection "FILESETS" 4609.IX Subsection "FILESETS"
4458Depending on what features you need you need to include one or more sets of files 4610Depending on what features you need you need to include one or more sets of files
4459in your application. 4611in your application.
4460.PP 4612.PP
4461\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 4613\fI\s-1CORE EVENT LOOP\s0\fR
4462.IX Subsection "CORE EVENT LOOP" 4614.IX Subsection "CORE EVENT LOOP"
4463.PP 4615.PP
4464To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual 4616To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
4465configuration (no autoconf): 4617configuration (no autoconf):
4466.PP 4618.PP
4493\& ev_vars.h 4645\& ev_vars.h
4494\& ev_wrap.h 4646\& ev_wrap.h
4495\& 4647\&
4496\& ev_win32.c required on win32 platforms only 4648\& ev_win32.c required on win32 platforms only
4497\& 4649\&
4498\& ev_select.c only when select backend is enabled (which is enabled by default) 4650\& ev_select.c only when select backend is enabled
4499\& ev_poll.c only when poll backend is enabled (disabled by default) 4651\& ev_poll.c only when poll backend is enabled
4500\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 4652\& ev_epoll.c only when the epoll backend is enabled
4653\& ev_linuxaio.c only when the linux aio backend is enabled
4654\& ev_iouring.c only when the linux io_uring backend is enabled
4501\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 4655\& ev_kqueue.c only when the kqueue backend is enabled
4502\& ev_port.c only when the solaris port backend is enabled (disabled by default) 4656\& ev_port.c only when the solaris port backend is enabled
4503.Ve 4657.Ve
4504.PP 4658.PP
4505\&\fIev.c\fR includes the backend files directly when enabled, so you only need 4659\&\fIev.c\fR includes the backend files directly when enabled, so you only need
4506to compile this single file. 4660to compile this single file.
4507.PP 4661.PP
4508\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR 4662\fI\s-1LIBEVENT COMPATIBILITY API\s0\fR
4509.IX Subsection "LIBEVENT COMPATIBILITY API" 4663.IX Subsection "LIBEVENT COMPATIBILITY API"
4510.PP 4664.PP
4511To include the libevent compatibility \s-1API\s0, also include: 4665To include the libevent compatibility \s-1API,\s0 also include:
4512.PP 4666.PP
4513.Vb 1 4667.Vb 1
4514\& #include "event.c" 4668\& #include "event.c"
4515.Ve 4669.Ve
4516.PP 4670.PP
4518.PP 4672.PP
4519.Vb 1 4673.Vb 1
4520\& #include "event.h" 4674\& #include "event.h"
4521.Ve 4675.Ve
4522.PP 4676.PP
4523in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. 4677in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR.
4524.PP 4678.PP
4525You need the following additional files for this: 4679You need the following additional files for this:
4526.PP 4680.PP
4527.Vb 2 4681.Vb 2
4528\& event.h 4682\& event.h
4529\& event.c 4683\& event.c
4530.Ve 4684.Ve
4531.PP 4685.PP
4532\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 4686\fI\s-1AUTOCONF SUPPORT\s0\fR
4533.IX Subsection "AUTOCONF SUPPORT" 4687.IX Subsection "AUTOCONF SUPPORT"
4534.PP 4688.PP
4535Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in 4689Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in
4536whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 4690whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
4537\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then 4691\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
4540For this of course you need the m4 file: 4694For this of course you need the m4 file:
4541.PP 4695.PP
4542.Vb 1 4696.Vb 1
4543\& libev.m4 4697\& libev.m4
4544.Ve 4698.Ve
4545.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 4699.SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0"
4546.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 4700.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
4547Libev can be configured via a variety of preprocessor symbols you have to 4701Libev can be configured via a variety of preprocessor symbols you have to
4548define before including (or compiling) any of its files. The default in 4702define before including (or compiling) any of its files. The default in
4549the absence of autoconf is documented for every option. 4703the absence of autoconf is documented for every option.
4550.PP 4704.PP
4551Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different 4705Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different
4552values when compiling libev vs. including \fIev.h\fR, so it is permissible 4706values when compiling libev vs. including \fIev.h\fR, so it is permissible
4553to redefine them before including \fIev.h\fR without breaking compatibility 4707to redefine them before including \fIev.h\fR without breaking compatibility
4554to a compiled library. All other symbols change the \s-1ABI\s0, which means all 4708to a compiled library. All other symbols change the \s-1ABI,\s0 which means all
4555users of libev and the libev code itself must be compiled with compatible 4709users of libev and the libev code itself must be compiled with compatible
4556settings. 4710settings.
4557.IP "\s-1EV_COMPAT3\s0 (h)" 4 4711.IP "\s-1EV_COMPAT3\s0 (h)" 4
4558.IX Item "EV_COMPAT3 (h)" 4712.IX Item "EV_COMPAT3 (h)"
4559Backwards compatibility is a major concern for libev. This is why this 4713Backwards compatibility is a major concern for libev. This is why this
4625If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is 4779If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is
4626available and will probe for kernel support at runtime. This will improve 4780available and will probe for kernel support at runtime. This will improve
4627\&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. 4781\&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption.
4628If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc 4782If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
46292.7 or newer, otherwise disabled. 47832.7 or newer, otherwise disabled.
4784.IP "\s-1EV_USE_SIGNALFD\s0" 4
4785.IX Item "EV_USE_SIGNALFD"
4786If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`signalfd ()\*(C'\fR is
4787available and will probe for kernel support at runtime. This enables
4788the use of \s-1EVFLAG_SIGNALFD\s0 for faster and simpler signal handling. If
4789undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
47902.7 or newer, otherwise disabled.
4791.IP "\s-1EV_USE_TIMERFD\s0" 4
4792.IX Item "EV_USE_TIMERFD"
4793If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`timerfd ()\*(C'\fR is
4794available and will probe for kernel support at runtime. This allows
4795libev to detect time jumps accurately. If undefined, it will be enabled
4796if the headers indicate GNU/Linux + Glibc 2.8 or newer and define
4797\&\f(CW\*(C`TFD_TIMER_CANCEL_ON_SET\*(C'\fR, otherwise disabled.
4798.IP "\s-1EV_USE_EVENTFD\s0" 4
4799.IX Item "EV_USE_EVENTFD"
4800If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is
4801available and will probe for kernel support at runtime. This will improve
4802\&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption.
4803If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
48042.7 or newer, otherwise disabled.
4630.IP "\s-1EV_USE_SELECT\s0" 4 4805.IP "\s-1EV_USE_SELECT\s0" 4
4631.IX Item "EV_USE_SELECT" 4806.IX Item "EV_USE_SELECT"
4632If undefined or defined to be \f(CW1\fR, libev will compile in support for the 4807If undefined or defined to be \f(CW1\fR, libev will compile in support for the
4633\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no 4808\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no
4634other method takes over, select will be it. Otherwise the select backend 4809other method takes over, select will be it. Otherwise the select backend
4668.IX Item "EV_WIN32_CLOSE_FD(fd)" 4843.IX Item "EV_WIN32_CLOSE_FD(fd)"
4669If programs implement their own fd to handle mapping on win32, then this 4844If programs implement their own fd to handle mapping on win32, then this
4670macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister 4845macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister
4671file descriptors again. Note that the replacement function has to close 4846file descriptors again. Note that the replacement function has to close
4672the underlying \s-1OS\s0 handle. 4847the underlying \s-1OS\s0 handle.
4848.IP "\s-1EV_USE_WSASOCKET\s0" 4
4849.IX Item "EV_USE_WSASOCKET"
4850If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal
4851communication socket, which works better in some environments. Otherwise,
4852the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other
4853environments.
4673.IP "\s-1EV_USE_POLL\s0" 4 4854.IP "\s-1EV_USE_POLL\s0" 4
4674.IX Item "EV_USE_POLL" 4855.IX Item "EV_USE_POLL"
4675If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) 4856If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
4676backend. Otherwise it will be enabled on non\-win32 platforms. It 4857backend. Otherwise it will be enabled on non\-win32 platforms. It
4677takes precedence over select. 4858takes precedence over select.
4680If defined to be \f(CW1\fR, libev will compile in support for the Linux 4861If defined to be \f(CW1\fR, libev will compile in support for the Linux
4681\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, 4862\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
4682otherwise another method will be used as fallback. This is the preferred 4863otherwise another method will be used as fallback. This is the preferred
4683backend for GNU/Linux systems. If undefined, it will be enabled if the 4864backend for GNU/Linux systems. If undefined, it will be enabled if the
4684headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. 4865headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
4866.IP "\s-1EV_USE_LINUXAIO\s0" 4
4867.IX Item "EV_USE_LINUXAIO"
4868If defined to be \f(CW1\fR, libev will compile in support for the Linux aio
4869backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be
4870enabled on linux, otherwise disabled.
4871.IP "\s-1EV_USE_IOURING\s0" 4
4872.IX Item "EV_USE_IOURING"
4873If defined to be \f(CW1\fR, libev will compile in support for the Linux
4874io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's
4875current limitations it has to be requested explicitly. If undefined, it
4876will be enabled on linux, otherwise disabled.
4685.IP "\s-1EV_USE_KQUEUE\s0" 4 4877.IP "\s-1EV_USE_KQUEUE\s0" 4
4686.IX Item "EV_USE_KQUEUE" 4878.IX Item "EV_USE_KQUEUE"
4687If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style 4879If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
4688\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, 4880\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
4689otherwise another method will be used as fallback. This is the preferred 4881otherwise another method will be used as fallback. This is the preferred
4714between threads, that is, threads can be used, but threads never run on 4906between threads, that is, threads can be used, but threads never run on
4715different cpus (or different cpu cores). This reduces dependencies 4907different cpus (or different cpu cores). This reduces dependencies
4716and makes libev faster. 4908and makes libev faster.
4717.IP "\s-1EV_NO_THREADS\s0" 4 4909.IP "\s-1EV_NO_THREADS\s0" 4
4718.IX Item "EV_NO_THREADS" 4910.IX Item "EV_NO_THREADS"
4719If defined to be \f(CW1\fR, libev will assume that it will never be called 4911If defined to be \f(CW1\fR, libev will assume that it will never be called from
4720from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, 4912different threads (that includes signal handlers), which is a stronger
4721above. This reduces dependencies and makes libev faster. 4913assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes
4914libev faster.
4722.IP "\s-1EV_ATOMIC_T\s0" 4 4915.IP "\s-1EV_ATOMIC_T\s0" 4
4723.IX Item "EV_ATOMIC_T" 4916.IX Item "EV_ATOMIC_T"
4724Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose 4917Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose
4725access is atomic and serialised with respect to other threads or signal 4918access is atomic with respect to other threads or signal contexts. No
4726contexts. No such type is easily found in the C language, so you can 4919such type is easily found in the C language, so you can provide your own
4727provide your own type that you know is safe for your purposes. It is used 4920type that you know is safe for your purposes. It is used both for signal
4728both for signal handler \*(L"locking\*(R" as well as for signal and thread safety 4921handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR
4729in \f(CW\*(C`ev_async\*(C'\fR watchers. 4922watchers.
4730.Sp 4923.Sp
4731In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR 4924In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR
4732(from \fIsignal.h\fR), which is usually good enough on most platforms, 4925(from \fIsignal.h\fR), which is usually good enough on most platforms.
4733although strictly speaking using a type that also implies a memory fence
4734is required.
4735.IP "\s-1EV_H\s0 (h)" 4 4926.IP "\s-1EV_H\s0 (h)" 4
4736.IX Item "EV_H (h)" 4927.IX Item "EV_H (h)"
4737The name of the \fIev.h\fR header file used to include it. The default if 4928The name of the \fIev.h\fR header file used to include it. The default if
4738undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be 4929undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be
4739used to virtually rename the \fIev.h\fR header file in case of conflicts. 4930used to virtually rename the \fIev.h\fR header file in case of conflicts.
4778all the priorities, so having many of them (hundreds) uses a lot of space 4969all the priorities, so having many of them (hundreds) uses a lot of space
4779and time, so using the defaults of five priorities (\-2 .. +2) is usually 4970and time, so using the defaults of five priorities (\-2 .. +2) is usually
4780fine. 4971fine.
4781.Sp 4972.Sp
4782If your embedding application does not need any priorities, defining these 4973If your embedding application does not need any priorities, defining these
4783both to \f(CW0\fR will save some memory and \s-1CPU\s0. 4974both to \f(CW0\fR will save some memory and \s-1CPU.\s0
4784.IP "\s-1EV_PERIODIC_ENABLE\s0, \s-1EV_IDLE_ENABLE\s0, \s-1EV_EMBED_ENABLE\s0, \s-1EV_STAT_ENABLE\s0, \s-1EV_PREPARE_ENABLE\s0, \s-1EV_CHECK_ENABLE\s0, \s-1EV_FORK_ENABLE\s0, \s-1EV_SIGNAL_ENABLE\s0, \s-1EV_ASYNC_ENABLE\s0, \s-1EV_CHILD_ENABLE\s0." 4 4975.IP "\s-1EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE.\s0" 4
4785.IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." 4976.IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE."
4786If undefined or defined to be \f(CW1\fR (and the platform supports it), then 4977If undefined or defined to be \f(CW1\fR (and the platform supports it), then
4787the respective watcher type is supported. If defined to be \f(CW0\fR, then it 4978the respective watcher type is supported. If defined to be \f(CW0\fR, then it
4788is not. Disabling watcher types mainly saves code size. 4979is not. Disabling watcher types mainly saves code size.
4789.IP "\s-1EV_FEATURES\s0" 4 4980.IP "\s-1EV_FEATURES\s0" 4
4947called. If set to \f(CW2\fR, then the internal verification code will be 5138called. If set to \f(CW2\fR, then the internal verification code will be
4948called once per loop, which can slow down libev. If set to \f(CW3\fR, then the 5139called once per loop, which can slow down libev. If set to \f(CW3\fR, then the
4949verification code will be called very frequently, which will slow down 5140verification code will be called very frequently, which will slow down
4950libev considerably. 5141libev considerably.
4951.Sp 5142.Sp
5143Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you
5144disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported.
5145.Sp
4952The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it 5146The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it
4953will be \f(CW0\fR. 5147will be \f(CW0\fR.
4954.IP "\s-1EV_COMMON\s0" 4 5148.IP "\s-1EV_COMMON\s0" 4
4955.IX Item "EV_COMMON" 5149.IX Item "EV_COMMON"
4956By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 5150By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
4977and the way callbacks are invoked and set. Must expand to a struct member 5171and the way callbacks are invoked and set. Must expand to a struct member
4978definition and a statement, respectively. See the \fIev.h\fR header file for 5172definition and a statement, respectively. See the \fIev.h\fR header file for
4979their default definitions. One possible use for overriding these is to 5173their default definitions. One possible use for overriding these is to
4980avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 5174avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
4981method calls instead of plain function calls in \*(C+. 5175method calls instead of plain function calls in \*(C+.
4982.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 5176.SS "\s-1EXPORTED API SYMBOLS\s0"
4983.IX Subsection "EXPORTED API SYMBOLS" 5177.IX Subsection "EXPORTED API SYMBOLS"
4984If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of 5178If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of
4985exported symbols, you can use the provided \fISymbol.*\fR files which list 5179exported symbols, you can use the provided \fISymbol.*\fR files which list
4986all public symbols, one per line: 5180all public symbols, one per line:
4987.PP 5181.PP
5041\& #include "ev_cpp.h" 5235\& #include "ev_cpp.h"
5042\& #include "ev.c" 5236\& #include "ev.c"
5043.Ve 5237.Ve
5044.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5238.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
5045.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5239.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
5046.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 5240.SS "\s-1THREADS AND COROUTINES\s0"
5047.IX Subsection "THREADS AND COROUTINES" 5241.IX Subsection "THREADS AND COROUTINES"
5048\fI\s-1THREADS\s0\fR 5242\fI\s-1THREADS\s0\fR
5049.IX Subsection "THREADS" 5243.IX Subsection "THREADS"
5050.PP 5244.PP
5051All libev functions are reentrant and thread-safe unless explicitly 5245All libev functions are reentrant and thread-safe unless explicitly
5097An example use would be to communicate signals or other events that only 5291An example use would be to communicate signals or other events that only
5098work in the default loop by registering the signal watcher with the 5292work in the default loop by registering the signal watcher with the
5099default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop 5293default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop
5100watcher callback into the event loop interested in the signal. 5294watcher callback into the event loop interested in the signal.
5101.PP 5295.PP
5102See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". 5296See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0.
5103.PP 5297.PP
5104\fI\s-1COROUTINES\s0\fR 5298\fI\s-1COROUTINES\s0\fR
5105.IX Subsection "COROUTINES" 5299.IX Subsection "COROUTINES"
5106.PP 5300.PP
5107Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 5301Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
5112that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 5306that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
5113.PP 5307.PP
5114Care has been taken to ensure that libev does not keep local state inside 5308Care has been taken to ensure that libev does not keep local state inside
5115\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as 5309\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as
5116they do not call any callbacks. 5310they do not call any callbacks.
5117.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" 5311.SS "\s-1COMPILER WARNINGS\s0"
5118.IX Subsection "COMPILER WARNINGS" 5312.IX Subsection "COMPILER WARNINGS"
5119Depending on your compiler and compiler settings, you might get no or a 5313Depending on your compiler and compiler settings, you might get no or a
5120lot of warnings when compiling libev code. Some people are apparently 5314lot of warnings when compiling libev code. Some people are apparently
5121scared by this. 5315scared by this.
5122.PP 5316.PP
5174.PP 5368.PP
5175If you need, for some reason, empty reports from valgrind for your project 5369If you need, for some reason, empty reports from valgrind for your project
5176I suggest using suppression lists. 5370I suggest using suppression lists.
5177.SH "PORTABILITY NOTES" 5371.SH "PORTABILITY NOTES"
5178.IX Header "PORTABILITY NOTES" 5372.IX Header "PORTABILITY NOTES"
5179.SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" 5373.SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0"
5180.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" 5374.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS"
5181GNU/Linux is the only common platform that supports 64 bit file/large file 5375GNU/Linux is the only common platform that supports 64 bit file/large file
5182interfaces but \fIdisables\fR them by default. 5376interfaces but \fIdisables\fR them by default.
5183.PP 5377.PP
5184That means that libev compiled in the default environment doesn't support 5378That means that libev compiled in the default environment doesn't support
5185files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. 5379files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers.
5186.PP 5380.PP
5187Unfortunately, many programs try to work around this GNU/Linux issue 5381Unfortunately, many programs try to work around this GNU/Linux issue
5188by enabling the large file \s-1API\s0, which makes them incompatible with the 5382by enabling the large file \s-1API,\s0 which makes them incompatible with the
5189standard libev compiled for their system. 5383standard libev compiled for their system.
5190.PP 5384.PP
5191Likewise, libev cannot enable the large file \s-1API\s0 itself as this would 5385Likewise, libev cannot enable the large file \s-1API\s0 itself as this would
5192suddenly make it incompatible to the default compile time environment, 5386suddenly make it incompatible to the default compile time environment,
5193i.e. all programs not using special compile switches. 5387i.e. all programs not using special compile switches.
5194.SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" 5388.SS "\s-1OS/X AND DARWIN BUGS\s0"
5195.IX Subsection "OS/X AND DARWIN BUGS" 5389.IX Subsection "OS/X AND DARWIN BUGS"
5196The whole thing is a bug if you ask me \- basically any system interface 5390The whole thing is a bug if you ask me \- basically any system interface
5197you touch is broken, whether it is locales, poll, kqueue or even the 5391you touch is broken, whether it is locales, poll, kqueue or even the
5198OpenGL drivers. 5392OpenGL drivers.
5199.PP 5393.PP
5221.PP 5415.PP
5222\fI\f(CI\*(C`select\*(C'\fI is buggy\fR 5416\fI\f(CI\*(C`select\*(C'\fI is buggy\fR
5223.IX Subsection "select is buggy" 5417.IX Subsection "select is buggy"
5224.PP 5418.PP
5225All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this 5419All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this
5226one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file 5420one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file
5227descriptors you can pass in to 1024 \- your program suddenly crashes when 5421descriptors you can pass in to 1024 \- your program suddenly crashes when
5228you use more. 5422you use more.
5229.PP 5423.PP
5230There is an undocumented \*(L"workaround\*(R" for this \- defining 5424There is an undocumented \*(L"workaround\*(R" for this \- defining
5231\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR 5425\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR
5232work on \s-1OS/X\s0. 5426work on \s-1OS/X.\s0
5233.SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5427.SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0"
5234.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" 5428.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS"
5235\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR 5429\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR
5236.IX Subsection "errno reentrancy" 5430.IX Subsection "errno reentrancy"
5237.PP 5431.PP
5238The default compile environment on Solaris is unfortunately so 5432The default compile environment on Solaris is unfortunately so
5255great. 5449great.
5256.PP 5450.PP
5257If you can't get it to work, you can try running the program by setting 5451If you can't get it to work, you can try running the program by setting
5258the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and 5452the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and
5259\&\f(CW\*(C`select\*(C'\fR backends. 5453\&\f(CW\*(C`select\*(C'\fR backends.
5260.SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" 5454.SS "\s-1AIX POLL BUG\s0"
5261.IX Subsection "AIX POLL BUG" 5455.IX Subsection "AIX POLL BUG"
5262\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around 5456\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around
5263this by trying to avoid the poll backend altogether (i.e. it's not even 5457this by trying to avoid the poll backend altogether (i.e. it's not even
5264compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine 5458compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine
5265with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. 5459with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway.
5266.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5460.SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0"
5267.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 5461.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
5268\fIGeneral issues\fR 5462\fIGeneral issues\fR
5269.IX Subsection "General issues" 5463.IX Subsection "General issues"
5270.PP 5464.PP
5271Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 5465Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
5340\& #define EV_USE_SELECT 1 5534\& #define EV_USE_SELECT 1
5341\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ 5535\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
5342.Ve 5536.Ve
5343.PP 5537.PP
5344Note that winsockets handling of fd sets is O(n), so you can easily get a 5538Note that winsockets handling of fd sets is O(n), so you can easily get a
5345complexity in the O(nA\*^X) range when using win32. 5539complexity in the O(nX) range when using win32.
5346.PP 5540.PP
5347\fILimited number of file descriptors\fR 5541\fILimited number of file descriptors\fR
5348.IX Subsection "Limited number of file descriptors" 5542.IX Subsection "Limited number of file descriptors"
5349.PP 5543.PP
5350Windows has numerous arbitrary (and low) limits on things. 5544Windows has numerous arbitrary (and low) limits on things.
5366by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR 5560by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR
5367(another arbitrary limit), but is broken in many versions of the Microsoft 5561(another arbitrary limit), but is broken in many versions of the Microsoft
5368runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets 5562runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets
5369(depending on windows version and/or the phase of the moon). To get more, 5563(depending on windows version and/or the phase of the moon). To get more,
5370you need to wrap all I/O functions and provide your own fd management, but 5564you need to wrap all I/O functions and provide your own fd management, but
5371the cost of calling select (O(nA\*^X)) will likely make this unworkable. 5565the cost of calling select (O(nX)) will likely make this unworkable.
5372.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 5566.SS "\s-1PORTABILITY REQUIREMENTS\s0"
5373.IX Subsection "PORTABILITY REQUIREMENTS" 5567.IX Subsection "PORTABILITY REQUIREMENTS"
5374In addition to a working ISO-C implementation and of course the 5568In addition to a working ISO-C implementation and of course the
5375backend-specific APIs, libev relies on a few additional extensions: 5569backend-specific APIs, libev relies on a few additional extensions:
5376.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 5570.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4
5377.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 5571.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
5378.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." 5572.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
5379Libev assumes not only that all watcher pointers have the same internal 5573Libev assumes not only that all watcher pointers have the same internal
5380structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also 5574structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also
5381assumes that the same (machine) code can be used to call any watcher 5575assumes that the same (machine) code can be used to call any watcher
5382callback: The watcher callbacks have different type signatures, but libev 5576callback: The watcher callbacks have different type signatures, but libev
5383calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. 5577calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally.
5578.IP "null pointers and integer zero are represented by 0 bytes" 4
5579.IX Item "null pointers and integer zero are represented by 0 bytes"
5580Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and
5581relies on this setting pointers and integers to null.
5384.IP "pointer accesses must be thread-atomic" 4 5582.IP "pointer accesses must be thread-atomic" 4
5385.IX Item "pointer accesses must be thread-atomic" 5583.IX Item "pointer accesses must be thread-atomic"
5386Accessing a pointer value must be atomic, it must both be readable and 5584Accessing a pointer value must be atomic, it must both be readable and
5387writable in one piece \- this is the case on all current architectures. 5585writable in one piece \- this is the case on all current architectures.
5388.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 5586.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4
5401thread\*(R" or will block signals process-wide, both behaviours would 5599thread\*(R" or will block signals process-wide, both behaviours would
5402be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and 5600be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and
5403\&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. 5601\&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however.
5404.Sp 5602.Sp
5405The most portable way to handle signals is to block signals in all threads 5603The most portable way to handle signals is to block signals in all threads
5406except the initial one, and run the default loop in the initial thread as 5604except the initial one, and run the signal handling loop in the initial
5407well. 5605thread as well.
5408.ie n .IP """long"" must be large enough for common memory allocation sizes" 4 5606.ie n .IP """long"" must be large enough for common memory allocation sizes" 4
5409.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 5607.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4
5410.IX Item "long must be large enough for common memory allocation sizes" 5608.IX Item "long must be large enough for common memory allocation sizes"
5411To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally 5609To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally
5412instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX 5610instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX
5413systems (Microsoft...) this might be unexpectedly low, but is still at 5611systems (Microsoft...) this might be unexpectedly low, but is still at
5414least 31 bits everywhere, which is enough for hundreds of millions of 5612least 31 bits everywhere, which is enough for hundreds of millions of
5415watchers. 5613watchers.
5416.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 5614.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4
5418.IX Item "double must hold a time value in seconds with enough accuracy" 5616.IX Item "double must hold a time value in seconds with enough accuracy"
5419The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to 5617The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to
5420have at least 51 bits of mantissa (and 9 bits of exponent), which is 5618have at least 51 bits of mantissa (and 9 bits of exponent), which is
5421good enough for at least into the year 4000 with millisecond accuracy 5619good enough for at least into the year 4000 with millisecond accuracy
5422(the design goal for libev). This requirement is overfulfilled by 5620(the design goal for libev). This requirement is overfulfilled by
5423implementations using \s-1IEEE\s0 754, which is basically all existing ones. 5621implementations using \s-1IEEE 754,\s0 which is basically all existing ones.
5424.Sp 5622.Sp
5425With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the 5623With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the
5426year 2255 (and millisecond accuracy till the year 287396 \- by then, libev 5624year 2255 (and millisecond accuracy till the year 287396 \- by then, libev
5427is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or 5625is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or
5428something like that, just kidding). 5626something like that, just kidding).
5429.PP 5627.PP
5430If you know of other additional requirements drop me a note. 5628If you know of other additional requirements drop me a note.
5492calls in the current loop iteration and the loop is currently 5690calls in the current loop iteration and the loop is currently
5493blocked. Checking for async and signal events involves iterating over all 5691blocked. Checking for async and signal events involves iterating over all
5494running async watchers or all signal numbers. 5692running async watchers or all signal numbers.
5495.SH "PORTING FROM LIBEV 3.X TO 4.X" 5693.SH "PORTING FROM LIBEV 3.X TO 4.X"
5496.IX Header "PORTING FROM LIBEV 3.X TO 4.X" 5694.IX Header "PORTING FROM LIBEV 3.X TO 4.X"
5497The major version 4 introduced some incompatible changes to the \s-1API\s0. 5695The major version 4 introduced some incompatible changes to the \s-1API.\s0
5498.PP 5696.PP
5499At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions 5697At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions
5500for all changes, so most programs should still compile. The compatibility 5698for all changes, so most programs should still compile. The compatibility
5501layer might be removed in later versions of libev, so better update to the 5699layer might be removed in later versions of libev, so better update to the
5502new \s-1API\s0 early than late. 5700new \s-1API\s0 early than late.
5503.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 5701.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4
5504.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 5702.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4
5505.IX Item "EV_COMPAT3 backwards compatibility mechanism" 5703.IX Item "EV_COMPAT3 backwards compatibility mechanism"
5506The backward compatibility mechanism can be controlled by 5704The backward compatibility mechanism can be controlled by
5507\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" 5705\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0
5508section. 5706section.
5509.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 5707.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4
5510.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 5708.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4
5511.IX Item "ev_default_destroy and ev_default_fork have been removed" 5709.IX Item "ev_default_destroy and ev_default_fork have been removed"
5512These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: 5710These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts:
5552.SH "GLOSSARY" 5750.SH "GLOSSARY"
5553.IX Header "GLOSSARY" 5751.IX Header "GLOSSARY"
5554.IP "active" 4 5752.IP "active" 4
5555.IX Item "active" 5753.IX Item "active"
5556A watcher is active as long as it has been started and not yet stopped. 5754A watcher is active as long as it has been started and not yet stopped.
5557See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5755See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5558.IP "application" 4 5756.IP "application" 4
5559.IX Item "application" 5757.IX Item "application"
5560In this document, an application is whatever is using libev. 5758In this document, an application is whatever is using libev.
5561.IP "backend" 4 5759.IP "backend" 4
5562.IX Item "backend" 5760.IX Item "backend"
5589The model used to describe how an event loop handles and processes 5787The model used to describe how an event loop handles and processes
5590watchers and events. 5788watchers and events.
5591.IP "pending" 4 5789.IP "pending" 4
5592.IX Item "pending" 5790.IX Item "pending"
5593A watcher is pending as soon as the corresponding event has been 5791A watcher is pending as soon as the corresponding event has been
5594detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5792detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5595.IP "real time" 4 5793.IP "real time" 4
5596.IX Item "real time" 5794.IX Item "real time"
5597The physical time that is observed. It is apparently strictly monotonic :) 5795The physical time that is observed. It is apparently strictly monotonic :)
5598.IP "wall-clock time" 4 5796.IP "wall-clock time" 4
5599.IX Item "wall-clock time" 5797.IX Item "wall-clock time"

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