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Revision 1.98 by root, Thu Feb 28 02:17:11 2013 UTC vs.
Revision 1.109 by root, Fri Dec 21 07:03:02 2018 UTC

1.\" Automatically generated by Pod::Man 2.25 (Pod::Simple 3.16) 1.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.29)
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122.\} 131.\}
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124.\" ======================================================================== 133.\" ========================================================================
125.\" 134.\"
126.IX Title "LIBEV 3" 135.IX Title "LIBEV 3"
127.TH LIBEV 3 "2013-02-28" "libev-4.11" "libev - high performance full featured event loop" 136.TH LIBEV 3 "2018-12-21" "libev-4.25" "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.
… …
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
… …
514.IX Item "EVFLAG_NOENV" 523.IX Item "EVFLAG_NOENV"
515If this flag bit is or'ed into the flag value (or the program runs setuid 524If 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 525or 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 526\&\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 527override 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 528useful to try out specific backends to test their performance, to work
520around bugs. 529around bugs, or to make libev threadsafe (accessing environment variables
530cannot be done in a threadsafe way, but usually it works if no other
531thread modifies them).
521.ie n .IP """EVFLAG_FORKCHECK""" 4 532.ie n .IP """EVFLAG_FORKCHECK""" 4
522.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 533.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
523.IX Item "EVFLAG_FORKCHECK" 534.IX Item "EVFLAG_FORKCHECK"
524Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also 535Instead 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. 536make libev check for a fork in each iteration by enabling this flag.
526.Sp 537.Sp
527This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, 538This 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 539and 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 540iterations 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 541GNU/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 542sequence 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). 543system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc
544versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again).
533.Sp 545.Sp
534The big advantage of this flag is that you can forget about fork (and 546The 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 547forget about forgetting to tell libev about forking, although you still
536flag. 548have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag.
537.Sp 549.Sp
538This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR 550This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
539environment variable. 551environment variable.
540.ie n .IP """EVFLAG_NOINOTIFY""" 4 552.ie n .IP """EVFLAG_NOINOTIFY""" 4
541.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 553.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4
… …
572\&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. 584\&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified.
573.Sp 585.Sp
574This flag's behaviour will become the default in future versions of libev. 586This flag's behaviour will become the default in future versions of libev.
575.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 587.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
576.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 588.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
577.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 589.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
578This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 590This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
579libev tries to roll its own fd_set with no limits on the number of fds, 591libev 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 592but 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 593using 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. 594usually the fastest backend for a low number of (low-numbered :) fds.
… …
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 603This 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 604\&\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). 605\&\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)" 4 606.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)" 4 607.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)" 608.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 609And this is your standard \fIpoll\fR\|(2) backend. It's more complicated
598than select, but handles sparse fds better and has no artificial 610than select, but handles sparse fds better and has no artificial
599limit on the number of fds you can use (except it will slow down 611limit 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, 612considerably 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 613i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for
… …
603.Sp 615.Sp
604This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and 616This 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. 617\&\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)" 4 618.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
607.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 619.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
608.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 620.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
609Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 621Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9
610kernels). 622kernels).
611.Sp 623.Sp
612For few fds, this backend is a bit little slower than poll and select, but 624For 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 625it scales phenomenally better. While poll and select usually scale like
… …
666.Sp 678.Sp
667This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as 679This 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. 680\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
669.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 681.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)" 4 682.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
671.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 683.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
672Kqueue deserves special mention, as at the time of this writing, it 684Kqueue deserves special mention, as at the time of this writing, it
673was broken on all BSDs except NetBSD (usually it doesn't work reliably 685was broken on all BSDs except NetBSD (usually it doesn't work reliably
674with anything but sockets and pipes, except on Darwin, where of course 686with anything but sockets and pipes, except on Darwin, where of course
675it's completely useless). Unlike epoll, however, whose brokenness 687it's completely useless). Unlike epoll, however, whose brokenness
676is by design, these kqueue bugs can (and eventually will) be fixed 688is by design, these kqueue bugs can (and eventually will) be fixed
… …
696While nominally embeddable in other event loops, this doesn't work 708While nominally embeddable in other event loops, this doesn't work
697everywhere, so you might need to test for this. And since it is broken 709everywhere, 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 710almost 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 711(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 712(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. 713also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets.
702.Sp 714.Sp
703This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with 715This 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 716\&\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. 717\&\f(CW\*(C`NOTE_EOF\*(C'\fR.
706.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 718.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
… …
710implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets 722implementation). 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 723and is not embeddable, which would limit the usefulness of this backend
712immensely. 724immensely.
713.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 725.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
714.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 726.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
715.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 727.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
716This uses the Solaris 10 event port mechanism. As with everything on Solaris, 728This 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)). 729it's really slow, but it still scales very well (O(active_fds)).
718.Sp 730.Sp
719While this backend scales well, it requires one system call per active 731While this backend scales well, it requires one system call per active
720file descriptor per loop iteration. For small and medium numbers of file 732file descriptor per loop iteration. For small and medium numbers of file
… …
799except in the rare occasion where you really need to free its resources. 811except 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 812If 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. 813and \f(CW\*(C`ev_loop_destroy\*(C'\fR.
802.IP "ev_loop_fork (loop)" 4 814.IP "ev_loop_fork (loop)" 4
803.IX Item "ev_loop_fork (loop)" 815.IX Item "ev_loop_fork (loop)"
804This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to 816This 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 817to reinitialise the kernel state for backends that have one. Despite
806name, you can call it anytime, but it makes most sense after forking, in 818the 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 819watchers (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. 820sense after forking, in the child process. You \fImust\fR call it (or use
821\&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR.
809.Sp 822.Sp
823In addition, if you want to reuse a loop (via this function or
824\&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR.
825.Sp
810Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after 826Again, 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 827a 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 828because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things
813during fork. 829during fork.
814.Sp 830.Sp
815On the other hand, you only need to call this function in the child 831On the other hand, you only need to call this function in the child
… …
1352example it might indicate that a fd is readable or writable, and if your 1368example 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 1369callbacks 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 1370the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded
1355programs, though, as the fd could already be closed and reused for another 1371programs, though, as the fd could already be closed and reused for another
1356thing, so beware. 1372thing, so beware.
1357.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1373.SS "\s-1GENERIC WATCHER FUNCTIONS\s0"
1358.IX Subsection "GENERIC WATCHER FUNCTIONS" 1374.IX Subsection "GENERIC WATCHER FUNCTIONS"
1359.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1375.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1360.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1376.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1361.IX Item "ev_init (ev_TYPE *watcher, callback)" 1377.IX Item "ev_init (ev_TYPE *watcher, callback)"
1362This macro initialises the generic portion of a watcher. The contents 1378This macro initialises the generic portion of a watcher. The contents
… …
1470or might not have been clamped to the valid range. 1486or might not have been clamped to the valid range.
1471.Sp 1487.Sp
1472The default priority used by watchers when no priority has been set is 1488The 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 :). 1489always \f(CW0\fR, which is supposed to not be too high and not be too low :).
1474.Sp 1490.Sp
1475See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of 1491See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of
1476priorities. 1492priorities.
1477.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 1493.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
1478.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" 1494.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 1495Invoke 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 1496\&\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. 1516not started in the first place.
1501.Sp 1517.Sp
1502See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related 1518See 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. 1519functions that do not need a watcher.
1504.PP 1520.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 1521See 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. 1522OWN COMPOSITE WATCHERS\*(R"\s0 idioms.
1507.SS "\s-1WATCHER\s0 \s-1STATES\s0" 1523.SS "\s-1WATCHER STATES\s0"
1508.IX Subsection "WATCHER STATES" 1524.IX Subsection "WATCHER STATES"
1509There are various watcher states mentioned throughout this manual \- 1525There are various watcher states mentioned throughout this manual \-
1510active, pending and so on. In this section these states and the rules to 1526active, 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 1527transition between them will be described in more detail \- and while these
1512rules might look complicated, they usually do \*(L"the right thing\*(R". 1528rules might look complicated, they usually do \*(L"the right thing\*(R".
… …
1555.Sp 1571.Sp
1556While stopped (and not pending) the watcher is essentially in the 1572While stopped (and not pending) the watcher is essentially in the
1557initialised state, that is, it can be reused, moved, modified in any way 1573initialised 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 1574you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR
1559it again). 1575it again).
1560.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1576.SS "\s-1WATCHER PRIORITY MODELS\s0"
1561.IX Subsection "WATCHER PRIORITY MODELS" 1577.IX Subsection "WATCHER PRIORITY MODELS"
1562Many event loops support \fIwatcher priorities\fR, which are usually small 1578Many event loops support \fIwatcher priorities\fR, which are usually small
1563integers that influence the ordering of event callback invocation 1579integers that influence the ordering of event callback invocation
1564between watchers in some way, all else being equal. 1580between watchers in some way, all else being equal.
1565.PP 1581.PP
… …
1763wish to read \- you would first have to request some data. 1779wish to read \- you would first have to request some data.
1764.PP 1780.PP
1765Since files are typically not-so-well supported by advanced notification 1781Since files are typically not-so-well supported by advanced notification
1766mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect 1782mechanism, 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 1783to 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 1784convenience: 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 1785usually 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 1786(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 1787\&\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 1788asynchronous I/O instead of with non-blocking I/O, it is still useful when
1773it \*(L"just works\*(R" instead of freezing. 1789it \*(L"just works\*(R" instead of freezing.
1774.PP 1790.PP
1775So avoid file descriptors pointing to files when you know it (e.g. use 1791So 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 1792libeio), 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 1793when you rarely read from a file instead of from a socket, and want to
1778reuse the same code path. 1794reuse the same code path.
1779.PP 1795.PP
1780\fIThe special problem of fork\fR 1796\fIThe special problem of fork\fR
1781.IX Subsection "The special problem of fork" 1797.IX Subsection "The special problem of fork"
… …
1791\fIThe special problem of \s-1SIGPIPE\s0\fR 1807\fIThe special problem of \s-1SIGPIPE\s0\fR
1792.IX Subsection "The special problem of SIGPIPE" 1808.IX Subsection "The special problem of SIGPIPE"
1793.PP 1809.PP
1794While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: 1810While 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 1811when 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 1812sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs
1797this is sensible behaviour, for daemons, this is usually undesirable. 1813this is sensible behaviour, for daemons, this is usually undesirable.
1798.PP 1814.PP
1799So when you encounter spurious, unexplained daemon exits, make sure you 1815So 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 1816ignore \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). 1817somewhere, as that would have given you a big clue).
1802.PP 1818.PP
1803\fIThe special problem of \fIaccept()\fIing when you can't\fR 1819\fIThe special problem of \fIaccept()\fIing when you can't\fR
1804.IX Subsection "The special problem of accept()ing when you can't" 1820.IX Subsection "The special problem of accept()ing when you can't"
1805.PP 1821.PP
1806Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, 1822Many 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 1823found in post\-2004 Linux) have the peculiar behaviour of not removing a
1808connection from the pending queue in all error cases. 1824connection from the pending queue in all error cases.
1809.PP 1825.PP
1810For example, larger servers often run out of file descriptors (because 1826For example, larger servers often run out of file descriptors (because
1811of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not 1827of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not
… …
2150.PP 2166.PP
2151The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR 2167The 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 2168time. This is usually the right thing as this timestamp refers to the time
2153of the event triggering whatever timeout you are modifying/starting. If 2169of the event triggering whatever timeout you are modifying/starting. If
2154you suspect event processing to be delayed and you \fIneed\fR to base the 2170you 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: 2171timeout on the current time, use something like the following to adjust
2172for it:
2156.PP 2173.PP
2157.Vb 1 2174.Vb 1
2158\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); 2175\& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.);
2159.Ve 2176.Ve
2160.PP 2177.PP
2161If the event loop is suspended for a long time, you can also force an 2178If 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 2179update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update
2163()\*(C'\fR. 2180()\*(C'\fR, although that will push the event time of all outstanding events
2181further into the future.
2164.PP 2182.PP
2165\fIThe special problem of unsynchronised clocks\fR 2183\fIThe special problem of unsynchronised clocks\fR
2166.IX Subsection "The special problem of unsynchronised clocks" 2184.IX Subsection "The special problem of unsynchronised clocks"
2167.PP 2185.PP
2168Modern systems have a variety of clocks \- libev itself uses the normal 2186Modern 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)" 2251.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
2234.PD 0 2252.PD 0
2235.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 2253.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)" 2254.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
2237.PD 2255.PD
2238Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR 2256Configure 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 2257negative 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 2258automatically 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, 2259then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR
2242until stopped manually. 2260seconds later, again, and again, until stopped manually.
2243.Sp 2261.Sp
2244The timer itself will do a best-effort at avoiding drift, that is, if 2262The 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 2263you configure a timer to trigger every 10 seconds, then it will normally
2246trigger at exactly 10 second intervals. If, however, your program cannot 2264trigger at exactly 10 second intervals. If, however, your program cannot
2247keep up with the timer (because it takes longer than those 10 seconds to 2265keep 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 2347Periodic watchers are also timers of a kind, but they are very versatile
2330(and unfortunately a bit complex). 2348(and unfortunately a bit complex).
2331.PP 2349.PP
2332Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or 2350Unlike \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 2351relative 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 2352(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 2353difference 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 2354time, and time jumps are not uncommon (e.g. when you adjust your
2337wrist-watch). 2355wrist-watch).
2338.PP 2356.PP
2339You can tell a periodic watcher to trigger after some specific point 2357You 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 2362\&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting
2345it, as it uses a relative timeout). 2363it, as it uses a relative timeout).
2346.PP 2364.PP
2347\&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex 2365\&\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 2366timers, 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 2367other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR
2350those cannot react to time jumps. 2368watchers, as those cannot react to time jumps.
2351.PP 2369.PP
2352As with timers, the callback is guaranteed to be invoked only when the 2370As 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 2371point in time where it is supposed to trigger has passed. If multiple
2354timers become ready during the same loop iteration then the ones with 2372timers become ready during the same loop iteration then the ones with
2355earlier time-out values are invoked before ones with later time-out values 2373earlier 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 2434In 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 2435ignored. Instead, each time the periodic watcher gets scheduled, the
2418reschedule callback will be called with the watcher as first, and the 2436reschedule callback will be called with the watcher as first, and the
2419current time as second argument. 2437current time as second argument.
2420.Sp 2438.Sp
2421\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, 2439\&\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 2440or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly
2423allowed by documentation here\fR. 2441allowed by documentation here\fR.
2424.Sp 2442.Sp
2425If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop 2443If 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 2444it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the
… …
2440It must return the next time to trigger, based on the passed time value 2458It must return the next time to trigger, based on the passed time value
2441(that is, the lowest time value larger than to the second argument). It 2459(that is, the lowest time value larger than to the second argument). It
2442will usually be called just before the callback will be triggered, but 2460will usually be called just before the callback will be triggered, but
2443might be called at other times, too. 2461might be called at other times, too.
2444.Sp 2462.Sp
2445\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or 2463\&\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. 2464equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
2447.Sp 2465.Sp
2448This can be used to create very complex timers, such as a timer that 2466This 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 2467triggers 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 2468the 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 2469this. Here is a (completely untested, no error checking) example on how to
2452reason I omitted it as an example). 2470do this:
2471.Sp
2472.Vb 1
2473\& #include <time.h>
2474\&
2475\& static ev_tstamp
2476\& my_rescheduler (ev_periodic *w, ev_tstamp now)
2477\& {
2478\& time_t tnow = (time_t)now;
2479\& struct tm tm;
2480\& localtime_r (&tnow, &tm);
2481\&
2482\& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day
2483\& ++tm.tm_mday; // midnight next day
2484\&
2485\& return mktime (&tm);
2486\& }
2487.Ve
2488.Sp
2489Note: this code might run into trouble on days that have more then two
2490midnights (beginning and end).
2453.RE 2491.RE
2454.RS 4 2492.RS 4
2455.RE 2493.RE
2456.IP "ev_periodic_again (loop, ev_periodic *)" 4 2494.IP "ev_periodic_again (loop, ev_periodic *)" 4
2457.IX Item "ev_periodic_again (loop, ev_periodic *)" 2495.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 2580only 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 2581default 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 2582\&\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. 2583the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop.
2546.PP 2584.PP
2547When the first watcher gets started will libev actually register something 2585Only 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 2586register something with the kernel. It thus coexists with your own signal
2549you don't register any with libev for the same signal). 2587handlers as long as you don't register any with libev for the same signal.
2550.PP 2588.PP
2551If possible and supported, libev will install its handlers with 2589If 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 2590\&\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 2591not 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 2592interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher
… …
2575The simplest way to ensure that the signal mask is reset in the child is 2613The simplest way to ensure that the signal mask is reset in the child is
2576to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will 2614to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will
2577catch fork calls done by libraries (such as the libc) as well. 2615catch fork calls done by libraries (such as the libc) as well.
2578.PP 2616.PP
2579In current versions of libev, the signal will not be blocked indefinitely 2617In current versions of libev, the signal will not be blocked indefinitely
2580unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces 2618unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces
2581the window of opportunity for problems, it will not go away, as libev 2619the window of opportunity for problems, it will not go away, as libev
2582\&\fIhas\fR to modify the signal mask, at least temporarily. 2620\&\fIhas\fR to modify the signal mask, at least temporarily.
2583.PP 2621.PP
2584So I can't stress this enough: \fIIf you do not reset your signal mask when 2622So I can't stress this enough: \fIIf you do not reset your signal mask when
2585you expect it to be empty, you have a race condition in your code\fR. This 2623you expect it to be empty, you have a race condition in your code\fR. This
… …
2615The signal the watcher watches out for. 2653The signal the watcher watches out for.
2616.PP 2654.PP
2617\fIExamples\fR 2655\fIExamples\fR
2618.IX Subsection "Examples" 2656.IX Subsection "Examples"
2619.PP 2657.PP
2620Example: Try to exit cleanly on \s-1SIGINT\s0. 2658Example: Try to exit cleanly on \s-1SIGINT.\s0
2621.PP 2659.PP
2622.Vb 5 2660.Vb 5
2623\& static void 2661\& static void
2624\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) 2662\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2625\& { 2663\& {
… …
2782compilation environment, which means that on systems with large file 2820compilation environment, which means that on systems with large file
2783support disabled by default, you get the 32 bit version of the stat 2821support disabled by default, you get the 32 bit version of the stat
2784structure. When using the library from programs that change the \s-1ABI\s0 to 2822structure. When using the library from programs that change the \s-1ABI\s0 to
2785use 64 bit file offsets the programs will fail. In that case you have to 2823use 64 bit file offsets the programs will fail. In that case you have to
2786compile libev with the same flags to get binary compatibility. This is 2824compile libev with the same flags to get binary compatibility. This is
2787obviously the case with any flags that change the \s-1ABI\s0, but the problem is 2825obviously the case with any flags that change the \s-1ABI,\s0 but the problem is
2788most noticeably displayed with ev_stat and large file support. 2826most noticeably displayed with ev_stat and large file support.
2789.PP 2827.PP
2790The solution for this is to lobby your distribution maker to make large 2828The solution for this is to lobby your distribution maker to make large
2791file interfaces available by default (as e.g. FreeBSD does) and not 2829file interfaces available by default (as e.g. FreeBSD does) and not
2792optional. Libev cannot simply switch on large file support because it has 2830optional. Libev cannot simply switch on large file support because it has
… …
3037.IX Subsection "ev_prepare and ev_check - customise your event loop!" 3075.IX Subsection "ev_prepare and ev_check - customise your event loop!"
3038Prepare and check watchers are often (but not always) used in pairs: 3076Prepare and check watchers are often (but not always) used in pairs:
3039prepare watchers get invoked before the process blocks and check watchers 3077prepare watchers get invoked before the process blocks and check watchers
3040afterwards. 3078afterwards.
3041.PP 3079.PP
3042You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter 3080You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the
3043the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR 3081current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or
3044watchers. Other loops than the current one are fine, however. The 3082\&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine,
3045rationale behind this is that you do not need to check for recursion in 3083however. The rationale behind this is that you do not need to check
3046those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, 3084for recursion in those watchers, i.e. the sequence will always be
3047\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be 3085\&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each
3048called in pairs bracketing the blocking call. 3086kind they will always be called in pairs bracketing the blocking call.
3049.PP 3087.PP
3050Their main purpose is to integrate other event mechanisms into libev and 3088Their main purpose is to integrate other event mechanisms into libev and
3051their use is somewhat advanced. They could be used, for example, to track 3089their use is somewhat advanced. They could be used, for example, to track
3052variable changes, implement your own watchers, integrate net-snmp or a 3090variable changes, implement your own watchers, integrate net-snmp or a
3053coroutine library and lots more. They are also occasionally useful if 3091coroutine library and lots more. They are also occasionally useful if
… …
3223.Ve 3261.Ve
3224.PP 3262.PP
3225Method 4: Do not use a prepare or check watcher because the module you 3263Method 4: Do not use a prepare or check watcher because the module you
3226want to embed is not flexible enough to support it. Instead, you can 3264want to embed is not flexible enough to support it. Instead, you can
3227override their poll function. The drawback with this solution is that the 3265override their poll function. The drawback with this solution is that the
3228main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses 3266main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses
3229this approach, effectively embedding \s-1EV\s0 as a client into the horrible 3267this approach, effectively embedding \s-1EV\s0 as a client into the horrible
3230libglib event loop. 3268libglib event loop.
3231.PP 3269.PP
3232.Vb 4 3270.Vb 4
3233\& static gint 3271\& static gint
… …
3347.PP 3385.PP
3348.Vb 3 3386.Vb 3
3349\& struct ev_loop *loop_hi = ev_default_init (0); 3387\& struct ev_loop *loop_hi = ev_default_init (0);
3350\& struct ev_loop *loop_lo = 0; 3388\& struct ev_loop *loop_lo = 0;
3351\& ev_embed embed; 3389\& ev_embed embed;
3352\& 3390\&
3353\& // see if there is a chance of getting one that works 3391\& // see if there is a chance of getting one that works
3354\& // (remember that a flags value of 0 means autodetection) 3392\& // (remember that a flags value of 0 means autodetection)
3355\& loop_lo = ev_embeddable_backends () & ev_recommended_backends () 3393\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
3356\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) 3394\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
3357\& : 0; 3395\& : 0;
… …
3373.PP 3411.PP
3374.Vb 3 3412.Vb 3
3375\& struct ev_loop *loop = ev_default_init (0); 3413\& struct ev_loop *loop = ev_default_init (0);
3376\& struct ev_loop *loop_socket = 0; 3414\& struct ev_loop *loop_socket = 0;
3377\& ev_embed embed; 3415\& ev_embed embed;
3378\& 3416\&
3379\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) 3417\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
3380\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) 3418\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
3381\& { 3419\& {
3382\& ev_embed_init (&embed, 0, loop_socket); 3420\& ev_embed_init (&embed, 0, loop_socket);
3383\& ev_embed_start (loop, &embed); 3421\& ev_embed_start (loop, &embed);
… …
3400of course. 3438of course.
3401.PP 3439.PP
3402\fIThe special problem of life after fork \- how is it possible?\fR 3440\fIThe special problem of life after fork \- how is it possible?\fR
3403.IX Subsection "The special problem of life after fork - how is it possible?" 3441.IX Subsection "The special problem of life after fork - how is it possible?"
3404.PP 3442.PP
3405Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set 3443Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set
3406up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This 3444up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This
3407sequence should be handled by libev without any problems. 3445sequence should be handled by libev without any problems.
3408.PP 3446.PP
3409This changes when the application actually wants to do event handling 3447This changes when the application actually wants to do event handling
3410in the child, or both parent in child, in effect \*(L"continuing\*(R" after the 3448in the child, or both parent in child, in effect \*(L"continuing\*(R" after the
… …
3627is a time window between the event loop checking and resetting the async 3665is a time window between the event loop checking and resetting the async
3628notification, and the callback being invoked. 3666notification, and the callback being invoked.
3629.SH "OTHER FUNCTIONS" 3667.SH "OTHER FUNCTIONS"
3630.IX Header "OTHER FUNCTIONS" 3668.IX Header "OTHER FUNCTIONS"
3631There are some other functions of possible interest. Described. Here. Now. 3669There are some other functions of possible interest. Described. Here. Now.
3632.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 3670.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4
3633.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 3671.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)"
3634This function combines a simple timer and an I/O watcher, calls your 3672This function combines a simple timer and an I/O watcher, calls your
3635callback on whichever event happens first and automatically stops both 3673callback on whichever event happens first and automatically stops both
3636watchers. This is useful if you want to wait for a single event on an fd 3674watchers. This is useful if you want to wait for a single event on an fd
3637or timeout without having to allocate/configure/start/stop/free one or 3675or timeout without having to allocate/configure/start/stop/free one or
3638more watchers yourself. 3676more watchers yourself.
… …
3650\&\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 3688\&\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
3651value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR 3689value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR
3652a timeout and an io event at the same time \- you probably should give io 3690a timeout and an io event at the same time \- you probably should give io
3653events precedence. 3691events precedence.
3654.Sp 3692.Sp
3655Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. 3693Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0
3656.Sp 3694.Sp
3657.Vb 7 3695.Vb 7
3658\& static void stdin_ready (int revents, void *arg) 3696\& static void stdin_ready (int revents, void *arg)
3659\& { 3697\& {
3660\& if (revents & EV_READ) 3698\& if (revents & EV_READ)
… …
3676.SH "COMMON OR USEFUL IDIOMS (OR BOTH)" 3714.SH "COMMON OR USEFUL IDIOMS (OR BOTH)"
3677.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" 3715.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)"
3678This section explains some common idioms that are not immediately 3716This section explains some common idioms that are not immediately
3679obvious. Note that examples are sprinkled over the whole manual, and this 3717obvious. Note that examples are sprinkled over the whole manual, and this
3680section only contains stuff that wouldn't fit anywhere else. 3718section only contains stuff that wouldn't fit anywhere else.
3681.SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 3719.SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0"
3682.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 3720.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
3683Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read 3721Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read
3684or modify at any time: libev will completely ignore it. This can be used 3722or modify at any time: libev will completely ignore it. This can be used
3685to associate arbitrary data with your watcher. If you need more data and 3723to associate arbitrary data with your watcher. If you need more data and
3686don't want to allocate memory separately and store a pointer to it in that 3724don't want to allocate memory separately and store a pointer to it in that
… …
3712\& } 3750\& }
3713.Ve 3751.Ve
3714.PP 3752.PP
3715More interesting and less C\-conformant ways of casting your callback 3753More interesting and less C\-conformant ways of casting your callback
3716function type instead have been omitted. 3754function type instead have been omitted.
3717.SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" 3755.SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0"
3718.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" 3756.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS"
3719Another common scenario is to use some data structure with multiple 3757Another common scenario is to use some data structure with multiple
3720embedded watchers, in effect creating your own watcher that combines 3758embedded watchers, in effect creating your own watcher that combines
3721multiple libev event sources into one \*(L"super-watcher\*(R": 3759multiple libev event sources into one \*(L"super-watcher\*(R":
3722.PP 3760.PP
… …
3750\& { 3788\& {
3751\& struct my_biggy big = (struct my_biggy *) 3789\& struct my_biggy big = (struct my_biggy *)
3752\& (((char *)w) \- offsetof (struct my_biggy, t2)); 3790\& (((char *)w) \- offsetof (struct my_biggy, t2));
3753\& } 3791\& }
3754.Ve 3792.Ve
3755.SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" 3793.SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0"
3756.IX Subsection "AVOIDING FINISHING BEFORE RETURNING" 3794.IX Subsection "AVOIDING FINISHING BEFORE RETURNING"
3757Often you have structures like this in event-based programs: 3795Often you have structures like this in event-based programs:
3758.PP 3796.PP
3759.Vb 4 3797.Vb 4
3760\& callback () 3798\& callback ()
… …
3793\& ev_feed_event (EV_A_ watcher, 0); 3831\& ev_feed_event (EV_A_ watcher, 0);
3794.Ve 3832.Ve
3795.PP 3833.PP
3796This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is 3834This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is
3797invoked, while not delaying callback invocation too much. 3835invoked, while not delaying callback invocation too much.
3798.SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" 3836.SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0"
3799.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" 3837.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS"
3800Often (especially in \s-1GUI\s0 toolkits) there are places where you have 3838Often (especially in \s-1GUI\s0 toolkits) there are places where you have
3801\&\fImodal\fR interaction, which is most easily implemented by recursively 3839\&\fImodal\fR interaction, which is most easily implemented by recursively
3802invoking \f(CW\*(C`ev_run\*(C'\fR. 3840invoking \f(CW\*(C`ev_run\*(C'\fR.
3803.PP 3841.PP
… …
3835\& exit_main_loop = 1; 3873\& exit_main_loop = 1;
3836\& 3874\&
3837\& // exit both 3875\& // exit both
3838\& exit_main_loop = exit_nested_loop = 1; 3876\& exit_main_loop = exit_nested_loop = 1;
3839.Ve 3877.Ve
3840.SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" 3878.SS "\s-1THREAD LOCKING EXAMPLE\s0"
3841.IX Subsection "THREAD LOCKING EXAMPLE" 3879.IX Subsection "THREAD LOCKING EXAMPLE"
3842Here is a fictitious example of how to run an event loop in a different 3880Here is a fictitious example of how to run an event loop in a different
3843thread from where callbacks are being invoked and watchers are 3881thread from where callbacks are being invoked and watchers are
3844created/added/removed. 3882created/added/removed.
3845.PP 3883.PP
… …
3986.PP 4024.PP
3987Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise 4025Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
3988an event loop currently blocking in the kernel will have no knowledge 4026an event loop currently blocking in the kernel will have no knowledge
3989about the newly added timer. By waking up the loop it will pick up any new 4027about the newly added timer. By waking up the loop it will pick up any new
3990watchers in the next event loop iteration. 4028watchers in the next event loop iteration.
3991.SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" 4029.SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0"
3992.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" 4030.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS"
3993While the overhead of a callback that e.g. schedules a thread is small, it 4031While the overhead of a callback that e.g. schedules a thread is small, it
3994is still an overhead. If you embed libev, and your main usage is with some 4032is still an overhead. If you embed libev, and your main usage is with some
3995kind of threads or coroutines, you might want to customise libev so that 4033kind of threads or coroutines, you might want to customise libev so that
3996doesn't need callbacks anymore. 4034doesn't need callbacks anymore.
… …
4032You can do similar tricks if you have, say, threads with an event queue \- 4070You can do similar tricks if you have, say, threads with an event queue \-
4033instead of storing a coroutine, you store the queue object and instead of 4071instead of storing a coroutine, you store the queue object and instead of
4034switching to a coroutine, you push the watcher onto the queue and notify 4072switching to a coroutine, you push the watcher onto the queue and notify
4035any waiters. 4073any waiters.
4036.PP 4074.PP
4037To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two 4075To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two
4038files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: 4076files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files:
4039.PP 4077.PP
4040.Vb 4 4078.Vb 4
4041\& // my_ev.h 4079\& // my_ev.h
4042\& #define EV_CB_DECLARE(type) struct my_coro *cb; 4080\& #define EV_CB_DECLARE(type) struct my_coro *cb;
4043\& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); 4081\& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb)
4044\& #include "../libev/ev.h" 4082\& #include "../libev/ev.h"
4045\& 4083\&
4046\& // my_ev.c 4084\& // my_ev.c
4047\& #define EV_H "my_ev.h" 4085\& #define EV_H "my_ev.h"
4048\& #include "../libev/ev.c" 4086\& #include "../libev/ev.c"
… …
4088The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the 4126The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the
4089libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 4127libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0
4090will work fine. 4128will work fine.
4091.PP 4129.PP
4092Proper exception specifications might have to be added to callbacks passed 4130Proper exception specifications might have to be added to callbacks passed
4093to libev: exceptions may be thrown only from watcher callbacks, all 4131to libev: exceptions may be thrown only from watcher callbacks, all other
4094other callbacks (allocator, syserr, loop acquire/release and periodic 4132callbacks (allocator, syserr, loop acquire/release and periodic reschedule
4095reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw 4133callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR
4096()\*(C'\fR specification. If you have code that needs to be compiled as both C 4134specification. If you have code that needs to be compiled as both C and
4097and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: 4135\&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this:
4098.PP 4136.PP
4099.Vb 6 4137.Vb 6
4100\& static void 4138\& static void
4101\& fatal_error (const char *msg) EV_THROW 4139\& fatal_error (const char *msg) EV_NOEXCEPT
4102\& { 4140\& {
4103\& perror (msg); 4141\& perror (msg);
4104\& abort (); 4142\& abort ();
4105\& } 4143\& }
4106\& 4144\&
… …
4234\& void operator() (ev::io &w, int revents) 4272\& void operator() (ev::io &w, int revents)
4235\& { 4273\& {
4236\& ... 4274\& ...
4237\& } 4275\& }
4238\& } 4276\& }
4239\& 4277\&
4240\& myfunctor f; 4278\& myfunctor f;
4241\& 4279\&
4242\& ev::io w; 4280\& ev::io w;
4243\& w.set (&f); 4281\& w.set (&f);
4244.Ve 4282.Ve
… …
4337there are additional modules that implement libev-compatible interfaces 4375there are additional modules that implement libev-compatible interfaces
4338to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), 4376to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays),
4339\&\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 4377\&\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
4340and \f(CW\*(C`EV::Glib\*(C'\fR). 4378and \f(CW\*(C`EV::Glib\*(C'\fR).
4341.Sp 4379.Sp
4342It can be found and installed via \s-1CPAN\s0, its homepage is at 4380It can be found and installed via \s-1CPAN,\s0 its homepage is at
4343<http://software.schmorp.de/pkg/EV>. 4381<http://software.schmorp.de/pkg/EV>.
4344.IP "Python" 4 4382.IP "Python" 4
4345.IX Item "Python" 4383.IX Item "Python"
4346Python bindings can be found at <http://code.google.com/p/pyev/>. It 4384Python bindings can be found at <http://code.google.com/p/pyev/>. It
4347seems to be quite complete and well-documented. 4385seems to be quite complete and well-documented.
… …
4355Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR 4393Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR
4356makes rev work even on mingw. 4394makes rev work even on mingw.
4357.IP "Haskell" 4 4395.IP "Haskell" 4
4358.IX Item "Haskell" 4396.IX Item "Haskell"
4359A haskell binding to libev is available at 4397A haskell binding to libev is available at
4360http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. 4398<http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>.
4361.IP "D" 4 4399.IP "D" 4
4362.IX Item "D" 4400.IX Item "D"
4363Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to 4401Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to
4364be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. 4402be found at <http://www.llucax.com.ar/proj/ev.d/index.html>.
4365.IP "Ocaml" 4 4403.IP "Ocaml" 4
4366.IX Item "Ocaml" 4404.IX Item "Ocaml"
4367Erkki Seppala has written Ocaml bindings for libev, to be found at 4405Erkki Seppala has written Ocaml bindings for libev, to be found at
4368http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. 4406<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>.
4369.IP "Lua" 4 4407.IP "Lua" 4
4370.IX Item "Lua" 4408.IX Item "Lua"
4371Brian Maher has written a partial interface to libev for lua (at the 4409Brian Maher has written a partial interface to libev for lua (at the
4372time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at 4410time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at
4373http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. 4411<http://github.com/brimworks/lua\-ev>.
4374.IP "Javascript" 4 4412.IP "Javascript" 4
4375.IX Item "Javascript" 4413.IX Item "Javascript"
4376Node.js (<http://nodejs.org>) uses libev as the underlying event library. 4414Node.js (<http://nodejs.org>) uses libev as the underlying event library.
4377.IP "Others" 4 4415.IP "Others" 4
4378.IX Item "Others" 4416.IX Item "Others"
… …
4467.SS "\s-1FILESETS\s0" 4505.SS "\s-1FILESETS\s0"
4468.IX Subsection "FILESETS" 4506.IX Subsection "FILESETS"
4469Depending on what features you need you need to include one or more sets of files 4507Depending on what features you need you need to include one or more sets of files
4470in your application. 4508in your application.
4471.PP 4509.PP
4472\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 4510\fI\s-1CORE EVENT LOOP\s0\fR
4473.IX Subsection "CORE EVENT LOOP" 4511.IX Subsection "CORE EVENT LOOP"
4474.PP 4512.PP
4475To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual 4513To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
4476configuration (no autoconf): 4514configuration (no autoconf):
4477.PP 4515.PP
… …
4480\& #include "ev.c" 4518\& #include "ev.c"
4481.Ve 4519.Ve
4482.PP 4520.PP
4483This will automatically include \fIev.h\fR, too, and should be done in a 4521This will automatically include \fIev.h\fR, too, and should be done in a
4484single C source file only to provide the function implementations. To use 4522single C source file only to provide the function implementations. To use
4485it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best 4523it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best
4486done by writing a wrapper around \fIev.h\fR that you can include instead and 4524done by writing a wrapper around \fIev.h\fR that you can include instead and
4487where you can put other configuration options): 4525where you can put other configuration options):
4488.PP 4526.PP
4489.Vb 2 4527.Vb 2
4490\& #define EV_STANDALONE 1 4528\& #define EV_STANDALONE 1
… …
4504\& ev_vars.h 4542\& ev_vars.h
4505\& ev_wrap.h 4543\& ev_wrap.h
4506\& 4544\&
4507\& ev_win32.c required on win32 platforms only 4545\& ev_win32.c required on win32 platforms only
4508\& 4546\&
4509\& ev_select.c only when select backend is enabled (which is enabled by default) 4547\& ev_select.c only when select backend is enabled
4510\& ev_poll.c only when poll backend is enabled (disabled by default) 4548\& ev_poll.c only when poll backend is enabled
4511\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 4549\& ev_epoll.c only when the epoll backend is enabled
4512\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 4550\& ev_kqueue.c only when the kqueue backend is enabled
4513\& ev_port.c only when the solaris port backend is enabled (disabled by default) 4551\& ev_port.c only when the solaris port backend is enabled
4514.Ve 4552.Ve
4515.PP 4553.PP
4516\&\fIev.c\fR includes the backend files directly when enabled, so you only need 4554\&\fIev.c\fR includes the backend files directly when enabled, so you only need
4517to compile this single file. 4555to compile this single file.
4518.PP 4556.PP
4519\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR 4557\fI\s-1LIBEVENT COMPATIBILITY API\s0\fR
4520.IX Subsection "LIBEVENT COMPATIBILITY API" 4558.IX Subsection "LIBEVENT COMPATIBILITY API"
4521.PP 4559.PP
4522To include the libevent compatibility \s-1API\s0, also include: 4560To include the libevent compatibility \s-1API,\s0 also include:
4523.PP 4561.PP
4524.Vb 1 4562.Vb 1
4525\& #include "event.c" 4563\& #include "event.c"
4526.Ve 4564.Ve
4527.PP 4565.PP
… …
4529.PP 4567.PP
4530.Vb 1 4568.Vb 1
4531\& #include "event.h" 4569\& #include "event.h"
4532.Ve 4570.Ve
4533.PP 4571.PP
4534in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. 4572in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR.
4535.PP 4573.PP
4536You need the following additional files for this: 4574You need the following additional files for this:
4537.PP 4575.PP
4538.Vb 2 4576.Vb 2
4539\& event.h 4577\& event.h
4540\& event.c 4578\& event.c
4541.Ve 4579.Ve
4542.PP 4580.PP
4543\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 4581\fI\s-1AUTOCONF SUPPORT\s0\fR
4544.IX Subsection "AUTOCONF SUPPORT" 4582.IX Subsection "AUTOCONF SUPPORT"
4545.PP 4583.PP
4546Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in 4584Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in
4547whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 4585whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
4548\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then 4586\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
… …
4551For this of course you need the m4 file: 4589For this of course you need the m4 file:
4552.PP 4590.PP
4553.Vb 1 4591.Vb 1
4554\& libev.m4 4592\& libev.m4
4555.Ve 4593.Ve
4556.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 4594.SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0"
4557.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 4595.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
4558Libev can be configured via a variety of preprocessor symbols you have to 4596Libev can be configured via a variety of preprocessor symbols you have to
4559define before including (or compiling) any of its files. The default in 4597define before including (or compiling) any of its files. The default in
4560the absence of autoconf is documented for every option. 4598the absence of autoconf is documented for every option.
4561.PP 4599.PP
4562Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different 4600Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different
4563values when compiling libev vs. including \fIev.h\fR, so it is permissible 4601values when compiling libev vs. including \fIev.h\fR, so it is permissible
4564to redefine them before including \fIev.h\fR without breaking compatibility 4602to redefine them before including \fIev.h\fR without breaking compatibility
4565to a compiled library. All other symbols change the \s-1ABI\s0, which means all 4603to a compiled library. All other symbols change the \s-1ABI,\s0 which means all
4566users of libev and the libev code itself must be compiled with compatible 4604users of libev and the libev code itself must be compiled with compatible
4567settings. 4605settings.
4568.IP "\s-1EV_COMPAT3\s0 (h)" 4 4606.IP "\s-1EV_COMPAT3 \s0(h)" 4
4569.IX Item "EV_COMPAT3 (h)" 4607.IX Item "EV_COMPAT3 (h)"
4570Backwards compatibility is a major concern for libev. This is why this 4608Backwards compatibility is a major concern for libev. This is why this
4571release of libev comes with wrappers for the functions and symbols that 4609release of libev comes with wrappers for the functions and symbols that
4572have been renamed between libev version 3 and 4. 4610have been renamed between libev version 3 and 4.
4573.Sp 4611.Sp
… …
4578typedef in that case. 4616typedef in that case.
4579.Sp 4617.Sp
4580In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, 4618In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR,
4581and in some even more future version the compatibility code will be 4619and in some even more future version the compatibility code will be
4582removed completely. 4620removed completely.
4583.IP "\s-1EV_STANDALONE\s0 (h)" 4 4621.IP "\s-1EV_STANDALONE \s0(h)" 4
4584.IX Item "EV_STANDALONE (h)" 4622.IX Item "EV_STANDALONE (h)"
4585Must always be \f(CW1\fR if you do not use autoconf configuration, which 4623Must always be \f(CW1\fR if you do not use autoconf configuration, which
4586keeps libev from including \fIconfig.h\fR, and it also defines dummy 4624keeps libev from including \fIconfig.h\fR, and it also defines dummy
4587implementations for some libevent functions (such as logging, which is not 4625implementations for some libevent functions (such as logging, which is not
4588supported). It will also not define any of the structs usually found in 4626supported). It will also not define any of the structs usually found in
… …
4746handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR 4784handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR
4747watchers. 4785watchers.
4748.Sp 4786.Sp
4749In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR 4787In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR
4750(from \fIsignal.h\fR), which is usually good enough on most platforms. 4788(from \fIsignal.h\fR), which is usually good enough on most platforms.
4751.IP "\s-1EV_H\s0 (h)" 4 4789.IP "\s-1EV_H \s0(h)" 4
4752.IX Item "EV_H (h)" 4790.IX Item "EV_H (h)"
4753The name of the \fIev.h\fR header file used to include it. The default if 4791The name of the \fIev.h\fR header file used to include it. The default if
4754undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be 4792undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be
4755used to virtually rename the \fIev.h\fR header file in case of conflicts. 4793used to virtually rename the \fIev.h\fR header file in case of conflicts.
4756.IP "\s-1EV_CONFIG_H\s0 (h)" 4 4794.IP "\s-1EV_CONFIG_H \s0(h)" 4
4757.IX Item "EV_CONFIG_H (h)" 4795.IX Item "EV_CONFIG_H (h)"
4758If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override 4796If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
4759\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to 4797\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
4760\&\f(CW\*(C`EV_H\*(C'\fR, above. 4798\&\f(CW\*(C`EV_H\*(C'\fR, above.
4761.IP "\s-1EV_EVENT_H\s0 (h)" 4 4799.IP "\s-1EV_EVENT_H \s0(h)" 4
4762.IX Item "EV_EVENT_H (h)" 4800.IX Item "EV_EVENT_H (h)"
4763Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea 4801Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
4764of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. 4802of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR.
4765.IP "\s-1EV_PROTOTYPES\s0 (h)" 4 4803.IP "\s-1EV_PROTOTYPES \s0(h)" 4
4766.IX Item "EV_PROTOTYPES (h)" 4804.IX Item "EV_PROTOTYPES (h)"
4767If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function 4805If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
4768prototypes, but still define all the structs and other symbols. This is 4806prototypes, but still define all the structs and other symbols. This is
4769occasionally useful if you want to provide your own wrapper functions 4807occasionally useful if you want to provide your own wrapper functions
4770around libev functions. 4808around libev functions.
… …
4794all the priorities, so having many of them (hundreds) uses a lot of space 4832all the priorities, so having many of them (hundreds) uses a lot of space
4795and time, so using the defaults of five priorities (\-2 .. +2) is usually 4833and time, so using the defaults of five priorities (\-2 .. +2) is usually
4796fine. 4834fine.
4797.Sp 4835.Sp
4798If your embedding application does not need any priorities, defining these 4836If your embedding application does not need any priorities, defining these
4799both to \f(CW0\fR will save some memory and \s-1CPU\s0. 4837both to \f(CW0\fR will save some memory and \s-1CPU.\s0
4800.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 4838.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
4801.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." 4839.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."
4802If undefined or defined to be \f(CW1\fR (and the platform supports it), then 4840If undefined or defined to be \f(CW1\fR (and the platform supports it), then
4803the respective watcher type is supported. If defined to be \f(CW0\fR, then it 4841the respective watcher type is supported. If defined to be \f(CW0\fR, then it
4804is not. Disabling watcher types mainly saves code size. 4842is not. Disabling watcher types mainly saves code size.
4805.IP "\s-1EV_FEATURES\s0" 4 4843.IP "\s-1EV_FEATURES\s0" 4
… …
4979.Vb 3 5017.Vb 3
4980\& #define EV_COMMON \e 5018\& #define EV_COMMON \e
4981\& SV *self; /* contains this struct */ \e 5019\& SV *self; /* contains this struct */ \e
4982\& SV *cb_sv, *fh /* note no trailing ";" */ 5020\& SV *cb_sv, *fh /* note no trailing ";" */
4983.Ve 5021.Ve
4984.IP "\s-1EV_CB_DECLARE\s0 (type)" 4 5022.IP "\s-1EV_CB_DECLARE \s0(type)" 4
4985.IX Item "EV_CB_DECLARE (type)" 5023.IX Item "EV_CB_DECLARE (type)"
4986.PD 0 5024.PD 0
4987.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 5025.IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4
4988.IX Item "EV_CB_INVOKE (watcher, revents)" 5026.IX Item "EV_CB_INVOKE (watcher, revents)"
4989.IP "ev_set_cb (ev, cb)" 4 5027.IP "ev_set_cb (ev, cb)" 4
4990.IX Item "ev_set_cb (ev, cb)" 5028.IX Item "ev_set_cb (ev, cb)"
4991.PD 5029.PD
4992Can be used to change the callback member declaration in each watcher, 5030Can be used to change the callback member declaration in each watcher,
4993and the way callbacks are invoked and set. Must expand to a struct member 5031and the way callbacks are invoked and set. Must expand to a struct member
4994definition and a statement, respectively. See the \fIev.h\fR header file for 5032definition and a statement, respectively. See the \fIev.h\fR header file for
4995their default definitions. One possible use for overriding these is to 5033their default definitions. One possible use for overriding these is to
4996avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 5034avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
4997method calls instead of plain function calls in \*(C+. 5035method calls instead of plain function calls in \*(C+.
4998.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 5036.SS "\s-1EXPORTED API SYMBOLS\s0"
4999.IX Subsection "EXPORTED API SYMBOLS" 5037.IX Subsection "EXPORTED API SYMBOLS"
5000If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of 5038If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of
5001exported symbols, you can use the provided \fISymbol.*\fR files which list 5039exported symbols, you can use the provided \fISymbol.*\fR files which list
5002all public symbols, one per line: 5040all public symbols, one per line:
5003.PP 5041.PP
5004.Vb 2 5042.Vb 2
5005\& Symbols.ev for libev proper 5043\& Symbols.ev for libev proper
… …
5057\& #include "ev_cpp.h" 5095\& #include "ev_cpp.h"
5058\& #include "ev.c" 5096\& #include "ev.c"
5059.Ve 5097.Ve
5060.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5098.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
5061.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5099.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
5062.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 5100.SS "\s-1THREADS AND COROUTINES\s0"
5063.IX Subsection "THREADS AND COROUTINES" 5101.IX Subsection "THREADS AND COROUTINES"
5064\fI\s-1THREADS\s0\fR 5102\fI\s-1THREADS\s0\fR
5065.IX Subsection "THREADS" 5103.IX Subsection "THREADS"
5066.PP 5104.PP
5067All libev functions are reentrant and thread-safe unless explicitly 5105All libev functions are reentrant and thread-safe unless explicitly
… …
5113An example use would be to communicate signals or other events that only 5151An example use would be to communicate signals or other events that only
5114work in the default loop by registering the signal watcher with the 5152work in the default loop by registering the signal watcher with the
5115default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop 5153default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop
5116watcher callback into the event loop interested in the signal. 5154watcher callback into the event loop interested in the signal.
5117.PP 5155.PP
5118See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". 5156See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0.
5119.PP 5157.PP
5120\fI\s-1COROUTINES\s0\fR 5158\fI\s-1COROUTINES\s0\fR
5121.IX Subsection "COROUTINES" 5159.IX Subsection "COROUTINES"
5122.PP 5160.PP
5123Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 5161Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
… …
5128that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 5166that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
5129.PP 5167.PP
5130Care has been taken to ensure that libev does not keep local state inside 5168Care has been taken to ensure that libev does not keep local state inside
5131\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as 5169\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as
5132they do not call any callbacks. 5170they do not call any callbacks.
5133.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" 5171.SS "\s-1COMPILER WARNINGS\s0"
5134.IX Subsection "COMPILER WARNINGS" 5172.IX Subsection "COMPILER WARNINGS"
5135Depending on your compiler and compiler settings, you might get no or a 5173Depending on your compiler and compiler settings, you might get no or a
5136lot of warnings when compiling libev code. Some people are apparently 5174lot of warnings when compiling libev code. Some people are apparently
5137scared by this. 5175scared by this.
5138.PP 5176.PP
… …
5190.PP 5228.PP
5191If you need, for some reason, empty reports from valgrind for your project 5229If you need, for some reason, empty reports from valgrind for your project
5192I suggest using suppression lists. 5230I suggest using suppression lists.
5193.SH "PORTABILITY NOTES" 5231.SH "PORTABILITY NOTES"
5194.IX Header "PORTABILITY NOTES" 5232.IX Header "PORTABILITY NOTES"
5195.SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" 5233.SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0"
5196.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" 5234.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS"
5197GNU/Linux is the only common platform that supports 64 bit file/large file 5235GNU/Linux is the only common platform that supports 64 bit file/large file
5198interfaces but \fIdisables\fR them by default. 5236interfaces but \fIdisables\fR them by default.
5199.PP 5237.PP
5200That means that libev compiled in the default environment doesn't support 5238That means that libev compiled in the default environment doesn't support
5201files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. 5239files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers.
5202.PP 5240.PP
5203Unfortunately, many programs try to work around this GNU/Linux issue 5241Unfortunately, many programs try to work around this GNU/Linux issue
5204by enabling the large file \s-1API\s0, which makes them incompatible with the 5242by enabling the large file \s-1API,\s0 which makes them incompatible with the
5205standard libev compiled for their system. 5243standard libev compiled for their system.
5206.PP 5244.PP
5207Likewise, libev cannot enable the large file \s-1API\s0 itself as this would 5245Likewise, libev cannot enable the large file \s-1API\s0 itself as this would
5208suddenly make it incompatible to the default compile time environment, 5246suddenly make it incompatible to the default compile time environment,
5209i.e. all programs not using special compile switches. 5247i.e. all programs not using special compile switches.
5210.SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" 5248.SS "\s-1OS/X AND DARWIN BUGS\s0"
5211.IX Subsection "OS/X AND DARWIN BUGS" 5249.IX Subsection "OS/X AND DARWIN BUGS"
5212The whole thing is a bug if you ask me \- basically any system interface 5250The whole thing is a bug if you ask me \- basically any system interface
5213you touch is broken, whether it is locales, poll, kqueue or even the 5251you touch is broken, whether it is locales, poll, kqueue or even the
5214OpenGL drivers. 5252OpenGL drivers.
5215.PP 5253.PP
… …
5237.PP 5275.PP
5238\fI\f(CI\*(C`select\*(C'\fI is buggy\fR 5276\fI\f(CI\*(C`select\*(C'\fI is buggy\fR
5239.IX Subsection "select is buggy" 5277.IX Subsection "select is buggy"
5240.PP 5278.PP
5241All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this 5279All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this
5242one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file 5280one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file
5243descriptors you can pass in to 1024 \- your program suddenly crashes when 5281descriptors you can pass in to 1024 \- your program suddenly crashes when
5244you use more. 5282you use more.
5245.PP 5283.PP
5246There is an undocumented \*(L"workaround\*(R" for this \- defining 5284There is an undocumented \*(L"workaround\*(R" for this \- defining
5247\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR 5285\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR
5248work on \s-1OS/X\s0. 5286work on \s-1OS/X.\s0
5249.SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5287.SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0"
5250.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" 5288.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS"
5251\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR 5289\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR
5252.IX Subsection "errno reentrancy" 5290.IX Subsection "errno reentrancy"
5253.PP 5291.PP
5254The default compile environment on Solaris is unfortunately so 5292The default compile environment on Solaris is unfortunately so
… …
5271great. 5309great.
5272.PP 5310.PP
5273If you can't get it to work, you can try running the program by setting 5311If you can't get it to work, you can try running the program by setting
5274the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and 5312the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and
5275\&\f(CW\*(C`select\*(C'\fR backends. 5313\&\f(CW\*(C`select\*(C'\fR backends.
5276.SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" 5314.SS "\s-1AIX POLL BUG\s0"
5277.IX Subsection "AIX POLL BUG" 5315.IX Subsection "AIX POLL BUG"
5278\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around 5316\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around
5279this by trying to avoid the poll backend altogether (i.e. it's not even 5317this by trying to avoid the poll backend altogether (i.e. it's not even
5280compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine 5318compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine
5281with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. 5319with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway.
5282.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5320.SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0"
5283.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 5321.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
5284\fIGeneral issues\fR 5322\fIGeneral issues\fR
5285.IX Subsection "General issues" 5323.IX Subsection "General issues"
5286.PP 5324.PP
5287Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 5325Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
… …
5356\& #define EV_USE_SELECT 1 5394\& #define EV_USE_SELECT 1
5357\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ 5395\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
5358.Ve 5396.Ve
5359.PP 5397.PP
5360Note that winsockets handling of fd sets is O(n), so you can easily get a 5398Note that winsockets handling of fd sets is O(n), so you can easily get a
5361complexity in the O(nA\*^X) range when using win32. 5399complexity in the O(nX) range when using win32.
5362.PP 5400.PP
5363\fILimited number of file descriptors\fR 5401\fILimited number of file descriptors\fR
5364.IX Subsection "Limited number of file descriptors" 5402.IX Subsection "Limited number of file descriptors"
5365.PP 5403.PP
5366Windows has numerous arbitrary (and low) limits on things. 5404Windows has numerous arbitrary (and low) limits on things.
… …
5382by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR 5420by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR
5383(another arbitrary limit), but is broken in many versions of the Microsoft 5421(another arbitrary limit), but is broken in many versions of the Microsoft
5384runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets 5422runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets
5385(depending on windows version and/or the phase of the moon). To get more, 5423(depending on windows version and/or the phase of the moon). To get more,
5386you need to wrap all I/O functions and provide your own fd management, but 5424you need to wrap all I/O functions and provide your own fd management, but
5387the cost of calling select (O(nA\*^X)) will likely make this unworkable. 5425the cost of calling select (O(nX)) will likely make this unworkable.
5388.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 5426.SS "\s-1PORTABILITY REQUIREMENTS\s0"
5389.IX Subsection "PORTABILITY REQUIREMENTS" 5427.IX Subsection "PORTABILITY REQUIREMENTS"
5390In addition to a working ISO-C implementation and of course the 5428In addition to a working ISO-C implementation and of course the
5391backend-specific APIs, libev relies on a few additional extensions: 5429backend-specific APIs, libev relies on a few additional extensions:
5392.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 5430.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4
5393.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 5431.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
5394.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." 5432.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
5395Libev assumes not only that all watcher pointers have the same internal 5433Libev assumes not only that all watcher pointers have the same internal
5396structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also 5434structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also
5397assumes that the same (machine) code can be used to call any watcher 5435assumes that the same (machine) code can be used to call any watcher
5398callback: The watcher callbacks have different type signatures, but libev 5436callback: The watcher callbacks have different type signatures, but libev
5399calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. 5437calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally.
5438.IP "null pointers and integer zero are represented by 0 bytes" 4
5439.IX Item "null pointers and integer zero are represented by 0 bytes"
5440Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and
5441relies on this setting pointers and integers to null.
5400.IP "pointer accesses must be thread-atomic" 4 5442.IP "pointer accesses must be thread-atomic" 4
5401.IX Item "pointer accesses must be thread-atomic" 5443.IX Item "pointer accesses must be thread-atomic"
5402Accessing a pointer value must be atomic, it must both be readable and 5444Accessing a pointer value must be atomic, it must both be readable and
5403writable in one piece \- this is the case on all current architectures. 5445writable in one piece \- this is the case on all current architectures.
5404.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 5446.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4
… …
5422except the initial one, and run the signal handling loop in the initial 5464except the initial one, and run the signal handling loop in the initial
5423thread as well. 5465thread as well.
5424.ie n .IP """long"" must be large enough for common memory allocation sizes" 4 5466.ie n .IP """long"" must be large enough for common memory allocation sizes" 4
5425.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 5467.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4
5426.IX Item "long must be large enough for common memory allocation sizes" 5468.IX Item "long must be large enough for common memory allocation sizes"
5427To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally 5469To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally
5428instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX 5470instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX
5429systems (Microsoft...) this might be unexpectedly low, but is still at 5471systems (Microsoft...) this might be unexpectedly low, but is still at
5430least 31 bits everywhere, which is enough for hundreds of millions of 5472least 31 bits everywhere, which is enough for hundreds of millions of
5431watchers. 5473watchers.
5432.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 5474.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4
… …
5434.IX Item "double must hold a time value in seconds with enough accuracy" 5476.IX Item "double must hold a time value in seconds with enough accuracy"
5435The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to 5477The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to
5436have at least 51 bits of mantissa (and 9 bits of exponent), which is 5478have at least 51 bits of mantissa (and 9 bits of exponent), which is
5437good enough for at least into the year 4000 with millisecond accuracy 5479good enough for at least into the year 4000 with millisecond accuracy
5438(the design goal for libev). This requirement is overfulfilled by 5480(the design goal for libev). This requirement is overfulfilled by
5439implementations using \s-1IEEE\s0 754, which is basically all existing ones. 5481implementations using \s-1IEEE 754,\s0 which is basically all existing ones.
5440.Sp 5482.Sp
5441With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the 5483With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the
5442year 2255 (and millisecond accuracy till the year 287396 \- by then, libev 5484year 2255 (and millisecond accuracy till the year 287396 \- by then, libev
5443is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or 5485is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or
5444something like that, just kidding). 5486something like that, just kidding).
5445.PP 5487.PP
5446If you know of other additional requirements drop me a note. 5488If you know of other additional requirements drop me a note.
… …
5508calls in the current loop iteration and the loop is currently 5550calls in the current loop iteration and the loop is currently
5509blocked. Checking for async and signal events involves iterating over all 5551blocked. Checking for async and signal events involves iterating over all
5510running async watchers or all signal numbers. 5552running async watchers or all signal numbers.
5511.SH "PORTING FROM LIBEV 3.X TO 4.X" 5553.SH "PORTING FROM LIBEV 3.X TO 4.X"
5512.IX Header "PORTING FROM LIBEV 3.X TO 4.X" 5554.IX Header "PORTING FROM LIBEV 3.X TO 4.X"
5513The major version 4 introduced some incompatible changes to the \s-1API\s0. 5555The major version 4 introduced some incompatible changes to the \s-1API.\s0
5514.PP 5556.PP
5515At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions 5557At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions
5516for all changes, so most programs should still compile. The compatibility 5558for all changes, so most programs should still compile. The compatibility
5517layer might be removed in later versions of libev, so better update to the 5559layer might be removed in later versions of libev, so better update to the
5518new \s-1API\s0 early than late. 5560new \s-1API\s0 early than late.
5519.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 5561.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4
5520.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 5562.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4
5521.IX Item "EV_COMPAT3 backwards compatibility mechanism" 5563.IX Item "EV_COMPAT3 backwards compatibility mechanism"
5522The backward compatibility mechanism can be controlled by 5564The backward compatibility mechanism can be controlled by
5523\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" 5565\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0
5524section. 5566section.
5525.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 5567.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4
5526.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 5568.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4
5527.IX Item "ev_default_destroy and ev_default_fork have been removed" 5569.IX Item "ev_default_destroy and ev_default_fork have been removed"
5528These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: 5570These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts:
… …
5568.SH "GLOSSARY" 5610.SH "GLOSSARY"
5569.IX Header "GLOSSARY" 5611.IX Header "GLOSSARY"
5570.IP "active" 4 5612.IP "active" 4
5571.IX Item "active" 5613.IX Item "active"
5572A watcher is active as long as it has been started and not yet stopped. 5614A watcher is active as long as it has been started and not yet stopped.
5573See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5615See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5574.IP "application" 4 5616.IP "application" 4
5575.IX Item "application" 5617.IX Item "application"
5576In this document, an application is whatever is using libev. 5618In this document, an application is whatever is using libev.
5577.IP "backend" 4 5619.IP "backend" 4
5578.IX Item "backend" 5620.IX Item "backend"
… …
5605The model used to describe how an event loop handles and processes 5647The model used to describe how an event loop handles and processes
5606watchers and events. 5648watchers and events.
5607.IP "pending" 4 5649.IP "pending" 4
5608.IX Item "pending" 5650.IX Item "pending"
5609A watcher is pending as soon as the corresponding event has been 5651A watcher is pending as soon as the corresponding event has been
5610detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5652detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5611.IP "real time" 4 5653.IP "real time" 4
5612.IX Item "real time" 5654.IX Item "real time"
5613The physical time that is observed. It is apparently strictly monotonic :) 5655The physical time that is observed. It is apparently strictly monotonic :)
5614.IP "wall-clock time" 4 5656.IP "wall-clock time" 4
5615.IX Item "wall-clock time" 5657.IX Item "wall-clock time"

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