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1.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05) 1.\" Automatically generated by Pod::Man 2.22 (Pod::Simple 3.07)
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56.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index 48.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
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132.\" ======================================================================== 124.\" ========================================================================
133.\" 125.\"
134.IX Title "LIBEV 3" 126.IX Title "LIBEV 3"
135.TH LIBEV 3 "2009-04-25" "libev-3.6" "libev - high performance full featured event loop" 127.TH LIBEV 3 "2009-12-31" "libev-3.9" "libev - high performance full featured event loop"
136.\" For nroff, turn off justification. Always turn off hyphenation; it makes 128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
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138.if n .ad l 130.if n .ad l
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140.SH "NAME" 132.SH "NAME"
… …
142.SH "SYNOPSIS" 134.SH "SYNOPSIS"
143.IX Header "SYNOPSIS" 135.IX Header "SYNOPSIS"
144.Vb 1 136.Vb 1
145\& #include <ev.h> 137\& #include <ev.h>
146.Ve 138.Ve
147.Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" 139.SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0"
148.IX Subsection "EXAMPLE PROGRAM" 140.IX Subsection "EXAMPLE PROGRAM"
149.Vb 2 141.Vb 2
150\& // a single header file is required 142\& // a single header file is required
151\& #include <ev.h> 143\& #include <ev.h>
152\& 144\&
… …
230.PP 222.PP
231You register interest in certain events by registering so-called \fIevent 223You register interest in certain events by registering so-called \fIevent
232watchers\fR, which are relatively small C structures you initialise with the 224watchers\fR, which are relatively small C structures you initialise with the
233details of the event, and then hand it over to libev by \fIstarting\fR the 225details of the event, and then hand it over to libev by \fIstarting\fR the
234watcher. 226watcher.
235.Sh "\s-1FEATURES\s0" 227.SS "\s-1FEATURES\s0"
236.IX Subsection "FEATURES" 228.IX Subsection "FEATURES"
237Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the 229Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
238BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms 230BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
239for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface 231for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
240(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers 232(for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner
241with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals 233inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative
242(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event 234timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling
243watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 235(\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status
244\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as 236change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event
245file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 237loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and
246(\f(CW\*(C`ev_fork\*(C'\fR). 238\&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even
239limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR).
247.PP 240.PP
248It also is quite fast (see this 241It also is quite fast (see this
249benchmark comparing it to libevent 242<benchmark> comparing it to libevent
250for example). 243for example).
251.Sh "\s-1CONVENTIONS\s0" 244.SS "\s-1CONVENTIONS\s0"
252.IX Subsection "CONVENTIONS" 245.IX Subsection "CONVENTIONS"
253Libev is very configurable. In this manual the default (and most common) 246Libev is very configurable. In this manual the default (and most common)
254configuration will be described, which supports multiple event loops. For 247configuration will be described, which supports multiple event loops. For
255more info about various configuration options please have a look at 248more 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 249\&\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 250for 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`ev_loop *\*(C'\fR) will not have 251name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have
259this argument. 252this argument.
260.Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" 253.SS "\s-1TIME\s0 \s-1REPRESENTATION\s0"
261.IX Subsection "TIME REPRESENTATION" 254.IX Subsection "TIME REPRESENTATION"
262Libev represents time as a single floating point number, representing 255Libev represents time as a single floating point number, representing
263the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere 256the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere
264near the beginning of 1970, details are complicated, don't ask). This 257near the beginning of 1970, details are complicated, don't ask). This
265type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually 258type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually
… …
486forget about forgetting to tell libev about forking) when you use this 479forget about forgetting to tell libev about forking) when you use this
487flag. 480flag.
488.Sp 481.Sp
489This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR 482This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
490environment variable. 483environment variable.
484.ie n .IP """EVFLAG_NOINOTIFY""" 4
485.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4
486.IX Item "EVFLAG_NOINOTIFY"
487When this flag is specified, then libev will not attempt to use the
488\&\fIinotify\fR \s-1API\s0 for it's \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and
489testing, this flag can be useful to conserve inotify file descriptors, as
490otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle.
491.ie n .IP """EVFLAG_SIGNALFD""" 4
492.el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4
493.IX Item "EVFLAG_SIGNALFD"
494When this flag is specified, then libev will attempt to use the
495\&\fIsignalfd\fR \s-1API\s0 for it's \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This \s-1API\s0
496delivers signals synchronously, which makes it both faster and might make
497it possible to get the queued signal data. It can also simplify signal
498handling with threads, as long as you properly block signals in your
499threads that are not interested in handling them.
500.Sp
501Signalfd will not be used by default as this changes your signal mask, and
502there are a lot of shoddy libraries and programs (glib's threadpool for
503example) that can't properly initialise their signal masks.
491.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 504.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
492.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 505.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
493.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 506.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
494This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 507This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
495libev tries to roll its own fd_set with no limits on the number of fds, 508libev tries to roll its own fd_set with no limits on the number of fds,
… …
520This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and 533This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and
521\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. 534\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR.
522.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 535.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
523.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 536.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
524.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 537.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
538Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9
539kernels).
540.Sp
525For few fds, this backend is a bit little slower than poll and select, 541For few fds, this backend is a bit little slower than poll and select,
526but it scales phenomenally better. While poll and select usually scale 542but it scales phenomenally better. While poll and select usually scale
527like O(total_fds) where n is the total number of fds (or the highest fd), 543like O(total_fds) where n is the total number of fds (or the highest fd),
528epoll scales either O(1) or O(active_fds). 544epoll scales either O(1) or O(active_fds).
529.Sp 545.Sp
… …
643.Sp 659.Sp
644It is definitely not recommended to use this flag. 660It is definitely not recommended to use this flag.
645.RE 661.RE
646.RS 4 662.RS 4
647.Sp 663.Sp
648If one or more of these are or'ed into the flags value, then only these 664If one or more of the backend flags are or'ed into the flags value,
649backends will be tried (in the reverse order as listed here). If none are 665then only these backends will be tried (in the reverse order as listed
650specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. 666here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends
667()\*(C'\fR will be tried.
651.Sp 668.Sp
652Example: This is the most typical usage. 669Example: This is the most typical usage.
653.Sp 670.Sp
654.Vb 2 671.Vb 2
655\& if (!ev_default_loop (0)) 672\& if (!ev_default_loop (0))
… …
705as signal and child watchers) would need to be stopped manually. 722as signal and child watchers) would need to be stopped manually.
706.Sp 723.Sp
707In general it is not advisable to call this function except in the 724In general it is not advisable to call this function except in the
708rare occasion where you really need to free e.g. the signal handling 725rare occasion where you really need to free e.g. the signal handling
709pipe fds. If you need dynamically allocated loops it is better to use 726pipe fds. If you need dynamically allocated loops it is better to use
710\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). 727\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR.
711.IP "ev_loop_destroy (loop)" 4 728.IP "ev_loop_destroy (loop)" 4
712.IX Item "ev_loop_destroy (loop)" 729.IX Item "ev_loop_destroy (loop)"
713Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 730Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
714earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 731earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
715.IP "ev_default_fork ()" 4 732.IP "ev_default_fork ()" 4
… …
749happily wraps around with enough iterations. 766happily wraps around with enough iterations.
750.Sp 767.Sp
751This value can sometimes be useful as a generation counter of sorts (it 768This value can sometimes be useful as a generation counter of sorts (it
752\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with 769\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
753\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. 770\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
771.IP "unsigned int ev_loop_depth (loop)" 4
772.IX Item "unsigned int ev_loop_depth (loop)"
773Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of
774times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth.
775.Sp
776Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is
777\&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread),
778in which case it is higher.
779.Sp
780Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread
781etc.), doesn't count as exit.
754.IP "unsigned int ev_backend (loop)" 4 782.IP "unsigned int ev_backend (loop)" 4
755.IX Item "unsigned int ev_backend (loop)" 783.IX Item "unsigned int ev_backend (loop)"
756Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 784Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
757use. 785use.
758.IP "ev_tstamp ev_now (loop)" 4 786.IP "ev_tstamp ev_now (loop)" 4
… …
801Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the 829Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the
802event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). 830event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR).
803.IP "ev_loop (loop, int flags)" 4 831.IP "ev_loop (loop, int flags)" 4
804.IX Item "ev_loop (loop, int flags)" 832.IX Item "ev_loop (loop, int flags)"
805Finally, this is it, the event handler. This function usually is called 833Finally, this is it, the event handler. This function usually is called
806after you initialised all your watchers and you want to start handling 834after you have initialised all your watchers and you want to start
807events. 835handling events.
808.Sp 836.Sp
809If the flags argument is specified as \f(CW0\fR, it will not return until 837If the flags argument is specified as \f(CW0\fR, it will not return until
810either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. 838either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called.
811.Sp 839.Sp
812Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than 840Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than
… …
890.PD 918.PD
891Ref/unref can be used to add or remove a reference count on the event 919Ref/unref can be used to add or remove a reference count on the event
892loop: Every watcher keeps one reference, and as long as the reference 920loop: Every watcher keeps one reference, and as long as the reference
893count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. 921count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own.
894.Sp 922.Sp
895If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR 923This is useful when you have a watcher that you never intend to
896from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before 924unregister, but that nevertheless should not keep \f(CW\*(C`ev_loop\*(C'\fR from
925returning. In such a case, call \f(CW\*(C`ev_unref\*(C'\fR after starting, and \f(CW\*(C`ev_ref\*(C'\fR
897stopping it. 926before stopping it.
898.Sp 927.Sp
899As an example, libev itself uses this for its internal signal pipe: It 928As an example, libev itself uses this for its internal signal pipe: It
900is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from 929is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from
901exiting if no event watchers registered by it are active. It is also an 930exiting if no event watchers registered by it are active. It is also an
902excellent way to do this for generic recurring timers or from within 931excellent way to do this for generic recurring timers or from within
… …
946.Sp 975.Sp
947By setting a higher \fIio collect interval\fR you allow libev to spend more 976By setting a higher \fIio collect interval\fR you allow libev to spend more
948time collecting I/O events, so you can handle more events per iteration, 977time collecting I/O events, so you can handle more events per iteration,
949at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and 978at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and
950\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will 979\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will
951introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. 980introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The
981sleep time ensures that libev will not poll for I/O events more often then
982once per this interval, on average.
952.Sp 983.Sp
953Likewise, by setting a higher \fItimeout collect interval\fR you allow libev 984Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
954to spend more time collecting timeouts, at the expense of increased 985to spend more time collecting timeouts, at the expense of increased
955latency/jitter/inexactness (the watcher callback will be called 986latency/jitter/inexactness (the watcher callback will be called
956later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null 987later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null
… …
958.Sp 989.Sp
959Many (busy) programs can usually benefit by setting the I/O collect 990Many (busy) programs can usually benefit by setting the I/O collect
960interval to a value near \f(CW0.1\fR or so, which is often enough for 991interval to a value near \f(CW0.1\fR or so, which is often enough for
961interactive servers (of course not for games), likewise for timeouts. It 992interactive servers (of course not for games), likewise for timeouts. It
962usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, 993usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
963as this approaches the timing granularity of most systems. 994as this approaches the timing granularity of most systems. Note that if
995you do transactions with the outside world and you can't increase the
996parallelity, then this setting will limit your transaction rate (if you
997need to poll once per transaction and the I/O collect interval is 0.01,
998then you can't do more than 100 transations per second).
964.Sp 999.Sp
965Setting the \fItimeout collect interval\fR can improve the opportunity for 1000Setting the \fItimeout collect interval\fR can improve the opportunity for
966saving power, as the program will \*(L"bundle\*(R" timer callback invocations that 1001saving power, as the program will \*(L"bundle\*(R" timer callback invocations that
967are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of 1002are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of
968times the process sleeps and wakes up again. Another useful technique to 1003times the process sleeps and wakes up again. Another useful technique to
969reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure 1004reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure
970they fire on, say, one-second boundaries only. 1005they fire on, say, one-second boundaries only.
1006.Sp
1007Example: we only need 0.1s timeout granularity, and we wish not to poll
1008more often than 100 times per second:
1009.Sp
1010.Vb 2
1011\& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
1012\& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
1013.Ve
1014.IP "ev_invoke_pending (loop)" 4
1015.IX Item "ev_invoke_pending (loop)"
1016This call will simply invoke all pending watchers while resetting their
1017pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required,
1018but when overriding the invoke callback this call comes handy.
1019.IP "int ev_pending_count (loop)" 4
1020.IX Item "int ev_pending_count (loop)"
1021Returns the number of pending watchers \- zero indicates that no watchers
1022are pending.
1023.IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4
1024.IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))"
1025This overrides the invoke pending functionality of the loop: Instead of
1026invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call
1027this callback instead. This is useful, for example, when you want to
1028invoke the actual watchers inside another context (another thread etc.).
1029.Sp
1030If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new
1031callback.
1032.IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4
1033.IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))"
1034Sometimes you want to share the same loop between multiple threads. This
1035can be done relatively simply by putting mutex_lock/unlock calls around
1036each call to a libev function.
1037.Sp
1038However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to
1039wait for it to return. One way around this is to wake up the loop via
1040\&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR
1041and \fIacquire\fR callbacks on the loop.
1042.Sp
1043When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is
1044suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just
1045afterwards.
1046.Sp
1047Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and
1048\&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again.
1049.Sp
1050While event loop modifications are allowed between invocations of
1051\&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no
1052modifications done will affect the event loop, i.e. adding watchers will
1053have no effect on the set of file descriptors being watched, or the time
1054waited. Use an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it
1055to take note of any changes you made.
1056.Sp
1057In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between
1058invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR.
1059.Sp
1060See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this
1061document.
1062.IP "ev_set_userdata (loop, void *data)" 4
1063.IX Item "ev_set_userdata (loop, void *data)"
1064.PD 0
1065.IP "ev_userdata (loop)" 4
1066.IX Item "ev_userdata (loop)"
1067.PD
1068Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When
1069\&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns
1070\&\f(CW0.\fR
1071.Sp
1072These two functions can be used to associate arbitrary data with a loop,
1073and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and
1074\&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for
1075any other purpose as well.
971.IP "ev_loop_verify (loop)" 4 1076.IP "ev_loop_verify (loop)" 4
972.IX Item "ev_loop_verify (loop)" 1077.IX Item "ev_loop_verify (loop)"
973This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been 1078This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been
974compiled in, which is the default for non-minimal builds. It tries to go 1079compiled in, which is the default for non-minimal builds. It tries to go
975through all internal structures and checks them for validity. If anything 1080through all internal structures and checks them for validity. If anything
… …
1124example it might indicate that a fd is readable or writable, and if your 1229example it might indicate that a fd is readable or writable, and if your
1125callbacks is well-written it can just attempt the operation and cope with 1230callbacks is well-written it can just attempt the operation and cope with
1126the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded 1231the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded
1127programs, though, as the fd could already be closed and reused for another 1232programs, though, as the fd could already be closed and reused for another
1128thing, so beware. 1233thing, so beware.
1129.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1234.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
1130.IX Subsection "GENERIC WATCHER FUNCTIONS" 1235.IX Subsection "GENERIC WATCHER FUNCTIONS"
1131.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1236.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1132.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1237.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1133.IX Item "ev_init (ev_TYPE *watcher, callback)" 1238.IX Item "ev_init (ev_TYPE *watcher, callback)"
1134This macro initialises the generic portion of a watcher. The contents 1239This macro initialises the generic portion of a watcher. The contents
… …
1149.Vb 3 1254.Vb 3
1150\& ev_io w; 1255\& ev_io w;
1151\& ev_init (&w, my_cb); 1256\& ev_init (&w, my_cb);
1152\& ev_io_set (&w, STDIN_FILENO, EV_READ); 1257\& ev_io_set (&w, STDIN_FILENO, EV_READ);
1153.Ve 1258.Ve
1154.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 1259.ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4
1155.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 1260.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4
1156.IX Item "ev_TYPE_set (ev_TYPE *, [args])" 1261.IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])"
1157This macro initialises the type-specific parts of a watcher. You need to 1262This macro initialises the type-specific parts of a watcher. You need to
1158call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can 1263call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can
1159call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this 1264call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this
1160macro on a watcher that is active (it can be pending, however, which is a 1265macro on a watcher that is active (it can be pending, however, which is a
1161difference to the \f(CW\*(C`ev_init\*(C'\fR macro). 1266difference to the \f(CW\*(C`ev_init\*(C'\fR macro).
… …
1174Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. 1279Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step.
1175.Sp 1280.Sp
1176.Vb 1 1281.Vb 1
1177\& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); 1282\& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1178.Ve 1283.Ve
1179.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 1284.ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4
1180.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 1285.el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4
1181.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" 1286.IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)"
1182Starts (activates) the given watcher. Only active watchers will receive 1287Starts (activates) the given watcher. Only active watchers will receive
1183events. If the watcher is already active nothing will happen. 1288events. If the watcher is already active nothing will happen.
1184.Sp 1289.Sp
1185Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this 1290Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this
1186whole section. 1291whole section.
1187.Sp 1292.Sp
1188.Vb 1 1293.Vb 1
1189\& ev_io_start (EV_DEFAULT_UC, &w); 1294\& ev_io_start (EV_DEFAULT_UC, &w);
1190.Ve 1295.Ve
1191.ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 1296.ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4
1192.el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 1297.el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4
1193.IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" 1298.IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)"
1194Stops the given watcher if active, and clears the pending status (whether 1299Stops the given watcher if active, and clears the pending status (whether
1195the watcher was active or not). 1300the watcher was active or not).
1196.Sp 1301.Sp
1197It is possible that stopped watchers are pending \- for example, 1302It is possible that stopped watchers are pending \- for example,
1198non-repeating timers are being stopped when they become pending \- but 1303non-repeating timers are being stopped when they become pending \- but
… …
1217Returns the callback currently set on the watcher. 1322Returns the callback currently set on the watcher.
1218.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 1323.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
1219.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 1324.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
1220Change the callback. You can change the callback at virtually any time 1325Change the callback. You can change the callback at virtually any time
1221(modulo threads). 1326(modulo threads).
1222.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 1327.IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4
1223.IX Item "ev_set_priority (ev_TYPE *watcher, priority)" 1328.IX Item "ev_set_priority (ev_TYPE *watcher, int priority)"
1224.PD 0 1329.PD 0
1225.IP "int ev_priority (ev_TYPE *watcher)" 4 1330.IP "int ev_priority (ev_TYPE *watcher)" 4
1226.IX Item "int ev_priority (ev_TYPE *watcher)" 1331.IX Item "int ev_priority (ev_TYPE *watcher)"
1227.PD 1332.PD
1228Set and query the priority of the watcher. The priority is a small 1333Set and query the priority of the watcher. The priority is a small
… …
1258returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the 1363returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
1259watcher isn't pending it does nothing and returns \f(CW0\fR. 1364watcher isn't pending it does nothing and returns \f(CW0\fR.
1260.Sp 1365.Sp
1261Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its 1366Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its
1262callback to be invoked, which can be accomplished with this function. 1367callback to be invoked, which can be accomplished with this function.
1368.IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4
1369.IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)"
1370Feeds the given event set into the event loop, as if the specified event
1371had happened for the specified watcher (which must be a pointer to an
1372initialised but not necessarily started event watcher). Obviously you must
1373not free the watcher as long as it has pending events.
1374.Sp
1375Stopping the watcher, letting libev invoke it, or calling
1376\&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was
1377not started in the first place.
1378.Sp
1379See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related
1380functions that do not need a watcher.
1263.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 1381.SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
1264.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 1382.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
1265Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 1383Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
1266and read at any time: libev will completely ignore it. This can be used 1384and read at any time: libev will completely ignore it. This can be used
1267to associate arbitrary data with your watcher. If you need more data and 1385to associate arbitrary data with your watcher. If you need more data and
1268don't want to allocate memory and store a pointer to it in that data 1386don't want to allocate memory and store a pointer to it in that data
… …
1319\& #include <stddef.h> 1437\& #include <stddef.h>
1320\& 1438\&
1321\& static void 1439\& static void
1322\& t1_cb (EV_P_ ev_timer *w, int revents) 1440\& t1_cb (EV_P_ ev_timer *w, int revents)
1323\& { 1441\& {
1324\& struct my_biggy big = (struct my_biggy * 1442\& struct my_biggy big = (struct my_biggy *)
1325\& (((char *)w) \- offsetof (struct my_biggy, t1)); 1443\& (((char *)w) \- offsetof (struct my_biggy, t1));
1326\& } 1444\& }
1327\& 1445\&
1328\& static void 1446\& static void
1329\& t2_cb (EV_P_ ev_timer *w, int revents) 1447\& t2_cb (EV_P_ ev_timer *w, int revents)
1330\& { 1448\& {
1331\& struct my_biggy big = (struct my_biggy * 1449\& struct my_biggy big = (struct my_biggy *)
1332\& (((char *)w) \- offsetof (struct my_biggy, t2)); 1450\& (((char *)w) \- offsetof (struct my_biggy, t2));
1333\& } 1451\& }
1334.Ve 1452.Ve
1335.Sh "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1453.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0"
1336.IX Subsection "WATCHER PRIORITY MODELS" 1454.IX Subsection "WATCHER PRIORITY MODELS"
1337Many event loops support \fIwatcher priorities\fR, which are usually small 1455Many event loops support \fIwatcher priorities\fR, which are usually small
1338integers that influence the ordering of event callback invocation 1456integers that influence the ordering of event callback invocation
1339between watchers in some way, all else being equal. 1457between watchers in some way, all else being equal.
1340.PP 1458.PP
… …
1413\& // with the default priority are receiving events. 1531\& // with the default priority are receiving events.
1414\& ev_idle_start (EV_A_ &idle); 1532\& ev_idle_start (EV_A_ &idle);
1415\& } 1533\& }
1416\& 1534\&
1417\& static void 1535\& static void
1418\& idle\-cb (EV_P_ ev_idle *w, int revents) 1536\& idle_cb (EV_P_ ev_idle *w, int revents)
1419\& { 1537\& {
1420\& // actual processing 1538\& // actual processing
1421\& read (STDIN_FILENO, ...); 1539\& read (STDIN_FILENO, ...);
1422\& 1540\&
1423\& // have to start the I/O watcher again, as 1541\& // have to start the I/O watcher again, as
… …
1448watcher is stopped to your hearts content), or \fI[read\-write]\fR, which 1566watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
1449means you can expect it to have some sensible content while the watcher 1567means you can expect it to have some sensible content while the watcher
1450is active, but you can also modify it. Modifying it may not do something 1568is active, but you can also modify it. Modifying it may not do something
1451sensible or take immediate effect (or do anything at all), but libev will 1569sensible or take immediate effect (or do anything at all), but libev will
1452not crash or malfunction in any way. 1570not crash or malfunction in any way.
1453.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" 1571.ie n .SS """ev_io"" \- is this file descriptor readable or writable?"
1454.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" 1572.el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?"
1455.IX Subsection "ev_io - is this file descriptor readable or writable?" 1573.IX Subsection "ev_io - is this file descriptor readable or writable?"
1456I/O watchers check whether a file descriptor is readable or writable 1574I/O watchers check whether a file descriptor is readable or writable
1457in each iteration of the event loop, or, more precisely, when reading 1575in each iteration of the event loop, or, more precisely, when reading
1458would not block the process and writing would at least be able to write 1576would not block the process and writing would at least be able to write
1459some data. This behaviour is called level-triggering because you keep 1577some data. This behaviour is called level-triggering because you keep
… …
1587\& ev_io stdin_readable; 1705\& ev_io stdin_readable;
1588\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1706\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1589\& ev_io_start (loop, &stdin_readable); 1707\& ev_io_start (loop, &stdin_readable);
1590\& ev_loop (loop, 0); 1708\& ev_loop (loop, 0);
1591.Ve 1709.Ve
1592.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" 1710.ie n .SS """ev_timer"" \- relative and optionally repeating timeouts"
1593.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" 1711.el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
1594.IX Subsection "ev_timer - relative and optionally repeating timeouts" 1712.IX Subsection "ev_timer - relative and optionally repeating timeouts"
1595Timer watchers are simple relative timers that generate an event after a 1713Timer watchers are simple relative timers that generate an event after a
1596given time, and optionally repeating in regular intervals after that. 1714given time, and optionally repeating in regular intervals after that.
1597.PP 1715.PP
1598The timers are based on real time, that is, if you register an event that 1716The timers are based on real time, that is, if you register an event that
… …
1603.PP 1721.PP
1604The callback is guaranteed to be invoked only \fIafter\fR its timeout has 1722The callback is guaranteed to be invoked only \fIafter\fR its timeout has
1605passed (not \fIat\fR, so on systems with very low-resolution clocks this 1723passed (not \fIat\fR, so on systems with very low-resolution clocks this
1606might introduce a small delay). If multiple timers become ready during the 1724might introduce a small delay). If multiple timers become ready during the
1607same loop iteration then the ones with earlier time-out values are invoked 1725same loop iteration then the ones with earlier time-out values are invoked
1608before ones with later time-out values (but this is no longer true when a 1726before ones of the same priority with later time-out values (but this is
1609callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). 1727no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively).
1610.PP 1728.PP
1611\fIBe smart about timeouts\fR 1729\fIBe smart about timeouts\fR
1612.IX Subsection "Be smart about timeouts" 1730.IX Subsection "Be smart about timeouts"
1613.PP 1731.PP
1614Many real-world problems involve some kind of timeout, usually for error 1732Many real-world problems involve some kind of timeout, usually for error
… …
1661member and \f(CW\*(C`ev_timer_again\*(C'\fR. 1779member and \f(CW\*(C`ev_timer_again\*(C'\fR.
1662.Sp 1780.Sp
1663At start: 1781At start:
1664.Sp 1782.Sp
1665.Vb 3 1783.Vb 3
1666\& ev_timer_init (timer, callback); 1784\& ev_init (timer, callback);
1667\& timer\->repeat = 60.; 1785\& timer\->repeat = 60.;
1668\& ev_timer_again (loop, timer); 1786\& ev_timer_again (loop, timer);
1669.Ve 1787.Ve
1670.Sp 1788.Sp
1671Each time there is some activity: 1789Each time there is some activity:
… …
1740To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR 1858To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR
1741to the current time (meaning we just have some activity :), then call the 1859to the current time (meaning we just have some activity :), then call the
1742callback, which will \*(L"do the right thing\*(R" and start the timer: 1860callback, which will \*(L"do the right thing\*(R" and start the timer:
1743.Sp 1861.Sp
1744.Vb 3 1862.Vb 3
1745\& ev_timer_init (timer, callback); 1863\& ev_init (timer, callback);
1746\& last_activity = ev_now (loop); 1864\& last_activity = ev_now (loop);
1747\& callback (loop, timer, EV_TIMEOUT); 1865\& callback (loop, timer, EV_TIMEOUT);
1748.Ve 1866.Ve
1749.Sp 1867.Sp
1750And when there is some activity, simply store the current time in 1868And when there is some activity, simply store the current time in
… …
1813.Ve 1931.Ve
1814.PP 1932.PP
1815If the event loop is suspended for a long time, you can also force an 1933If the event loop is suspended for a long time, you can also force an
1816update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update 1934update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update
1817()\*(C'\fR. 1935()\*(C'\fR.
1936.PP
1937\fIThe special problems of suspended animation\fR
1938.IX Subsection "The special problems of suspended animation"
1939.PP
1940When you leave the server world it is quite customary to hit machines that
1941can suspend/hibernate \- what happens to the clocks during such a suspend?
1942.PP
1943Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
1944all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue
1945to run until the system is suspended, but they will not advance while the
1946system is suspended. That means, on resume, it will be as if the program
1947was frozen for a few seconds, but the suspend time will not be counted
1948towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time
1949clock advanced as expected, but if it is used as sole clocksource, then a
1950long suspend would be detected as a time jump by libev, and timers would
1951be adjusted accordingly.
1952.PP
1953I would not be surprised to see different behaviour in different between
1954operating systems, \s-1OS\s0 versions or even different hardware.
1955.PP
1956The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a
1957time jump in the monotonic clocks and the realtime clock. If the program
1958is suspended for a very long time, and monotonic clock sources are in use,
1959then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time
1960will be counted towards the timers. When no monotonic clock source is in
1961use, then libev will again assume a timejump and adjust accordingly.
1962.PP
1963It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR
1964and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get
1965deterministic behaviour in this case (you can do nothing against
1966\&\f(CW\*(C`SIGSTOP\*(C'\fR).
1818.PP 1967.PP
1819\fIWatcher-Specific Functions and Data Members\fR 1968\fIWatcher-Specific Functions and Data Members\fR
1820.IX Subsection "Watcher-Specific Functions and Data Members" 1969.IX Subsection "Watcher-Specific Functions and Data Members"
1821.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1970.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1822.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1971.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
… …
1847If the timer is repeating, either start it if necessary (with the 1996If the timer is repeating, either start it if necessary (with the
1848\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. 1997\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1849.Sp 1998.Sp
1850This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a 1999This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a
1851usage example. 2000usage example.
2001.IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4
2002.IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)"
2003Returns the remaining time until a timer fires. If the timer is active,
2004then this time is relative to the current event loop time, otherwise it's
2005the timeout value currently configured.
2006.Sp
2007That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns
2008\&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR
2009will return \f(CW4\fR. When the timer expires and is restarted, it will return
2010roughly \f(CW7\fR (likely slightly less as callback invocation takes some time,
2011too), and so on.
1852.IP "ev_tstamp repeat [read\-write]" 4 2012.IP "ev_tstamp repeat [read\-write]" 4
1853.IX Item "ev_tstamp repeat [read-write]" 2013.IX Item "ev_tstamp repeat [read-write]"
1854The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 2014The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1855or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), 2015or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any),
1856which is also when any modifications are taken into account. 2016which is also when any modifications are taken into account.
… …
1889\& 2049\&
1890\& // and in some piece of code that gets executed on any "activity": 2050\& // and in some piece of code that gets executed on any "activity":
1891\& // reset the timeout to start ticking again at 10 seconds 2051\& // reset the timeout to start ticking again at 10 seconds
1892\& ev_timer_again (&mytimer); 2052\& ev_timer_again (&mytimer);
1893.Ve 2053.Ve
1894.ie n .Sh """ev_periodic"" \- to cron or not to cron?" 2054.ie n .SS """ev_periodic"" \- to cron or not to cron?"
1895.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" 2055.el .SS "\f(CWev_periodic\fP \- to cron or not to cron?"
1896.IX Subsection "ev_periodic - to cron or not to cron?" 2056.IX Subsection "ev_periodic - to cron or not to cron?"
1897Periodic watchers are also timers of a kind, but they are very versatile 2057Periodic watchers are also timers of a kind, but they are very versatile
1898(and unfortunately a bit complex). 2058(and unfortunately a bit complex).
1899.PP 2059.PP
1900Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or 2060Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or
… …
2088\& ev_periodic hourly_tick; 2248\& ev_periodic hourly_tick;
2089\& ev_periodic_init (&hourly_tick, clock_cb, 2249\& ev_periodic_init (&hourly_tick, clock_cb,
2090\& fmod (ev_now (loop), 3600.), 3600., 0); 2250\& fmod (ev_now (loop), 3600.), 3600., 0);
2091\& ev_periodic_start (loop, &hourly_tick); 2251\& ev_periodic_start (loop, &hourly_tick);
2092.Ve 2252.Ve
2093.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" 2253.ie n .SS """ev_signal"" \- signal me when a signal gets signalled!"
2094.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" 2254.el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
2095.IX Subsection "ev_signal - signal me when a signal gets signalled!" 2255.IX Subsection "ev_signal - signal me when a signal gets signalled!"
2096Signal watchers will trigger an event when the process receives a specific 2256Signal watchers will trigger an event when the process receives a specific
2097signal one or more times. Even though signals are very asynchronous, libev 2257signal one or more times. Even though signals are very asynchronous, libev
2098will try it's best to deliver signals synchronously, i.e. as part of the 2258will try it's best to deliver signals synchronously, i.e. as part of the
2099normal event processing, like any other event. 2259normal event processing, like any other event.
2100.PP 2260.PP
2101If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would 2261If you want signals to be delivered truly asynchronously, just use
2102do without libev and forget about sharing the signal. You can even use 2262\&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing
2103\&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. 2263the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to
2264synchronously wake up an event loop.
2104.PP 2265.PP
2105You can configure as many watchers as you like per signal. Only when the 2266You can configure as many watchers as you like for the same signal, but
2267only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your
2268default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for
2269\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At
2270the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop.
2271.PP
2106first watcher gets started will libev actually register a signal handler 2272When the first watcher gets started will libev actually register something
2107with the kernel (thus it coexists with your own signal handlers as long as 2273with the kernel (thus it coexists with your own signal handlers as long as
2108you don't register any with libev for the same signal). Similarly, when 2274you don't register any with libev for the same signal).
2109the last signal watcher for a signal is stopped, libev will reset the
2110signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before).
2111.PP 2275.PP
2112If possible and supported, libev will install its handlers with 2276If possible and supported, libev will install its handlers with
2113\&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly 2277\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should
2114interrupted. If you have a problem with system calls getting interrupted by 2278not be unduly interrupted. If you have a problem with system calls getting
2115signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock 2279interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher
2116them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. 2280and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher.
2281.PP
2282\fIThe special problem of inheritance over fork/execve/pthread_create\fR
2283.IX Subsection "The special problem of inheritance over fork/execve/pthread_create"
2284.PP
2285Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition
2286(\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after
2287stopping it again), that is, libev might or might not block the signal,
2288and might or might not set or restore the installed signal handler.
2289.PP
2290While this does not matter for the signal disposition (libev never
2291sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on
2292\&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect
2293certain signals to be blocked.
2294.PP
2295This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset
2296the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good
2297choice usually).
2298.PP
2299The simplest way to ensure that the signal mask is reset in the child is
2300to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will
2301catch fork calls done by libraries (such as the libc) as well.
2302.PP
2303In current versions of libev, the signal will not be blocked indefinitely
2304unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces
2305the window of opportunity for problems, it will not go away, as libev
2306\&\fIhas\fR to modify the signal mask, at least temporarily.
2307.PP
2308So I can't stress this enough: \fIIf you do not reset your signal mask when
2309you expect it to be empty, you have a race condition in your code\fR. This
2310is not a libev-specific thing, this is true for most event libraries.
2117.PP 2311.PP
2118\fIWatcher-Specific Functions and Data Members\fR 2312\fIWatcher-Specific Functions and Data Members\fR
2119.IX Subsection "Watcher-Specific Functions and Data Members" 2313.IX Subsection "Watcher-Specific Functions and Data Members"
2120.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 2314.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
2121.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 2315.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
… …
2143\& 2337\&
2144\& ev_signal signal_watcher; 2338\& ev_signal signal_watcher;
2145\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 2339\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2146\& ev_signal_start (loop, &signal_watcher); 2340\& ev_signal_start (loop, &signal_watcher);
2147.Ve 2341.Ve
2148.ie n .Sh """ev_child"" \- watch out for process status changes" 2342.ie n .SS """ev_child"" \- watch out for process status changes"
2149.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 2343.el .SS "\f(CWev_child\fP \- watch out for process status changes"
2150.IX Subsection "ev_child - watch out for process status changes" 2344.IX Subsection "ev_child - watch out for process status changes"
2151Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 2345Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
2152some child status changes (most typically when a child of yours dies or 2346some child status changes (most typically when a child of yours dies or
2153exits). It is permissible to install a child watcher \fIafter\fR the child 2347exits). It is permissible to install a child watcher \fIafter\fR the child
2154has been forked (which implies it might have already exited), as long 2348has been forked (which implies it might have already exited), as long
2155as the event loop isn't entered (or is continued from a watcher), i.e., 2349as the event loop isn't entered (or is continued from a watcher), i.e.,
2156forking and then immediately registering a watcher for the child is fine, 2350forking and then immediately registering a watcher for the child is fine,
2157but forking and registering a watcher a few event loop iterations later is 2351but forking and registering a watcher a few event loop iterations later or
2158not. 2352in the next callback invocation is not.
2159.PP 2353.PP
2160Only the default event loop is capable of handling signals, and therefore 2354Only the default event loop is capable of handling signals, and therefore
2161you can only register child watchers in the default event loop. 2355you can only register child watchers in the default event loop.
2162.PP 2356.PP
2357Due to some design glitches inside libev, child watchers will always be
2358handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by
2359libev)
2360.PP
2163\fIProcess Interaction\fR 2361\fIProcess Interaction\fR
2164.IX Subsection "Process Interaction" 2362.IX Subsection "Process Interaction"
2165.PP 2363.PP
2166Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is 2364Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is
2167initialised. This is necessary to guarantee proper behaviour even if 2365initialised. This is necessary to guarantee proper behaviour even if the
2168the first child watcher is started after the child exits. The occurrence 2366first child watcher is started after the child exits. The occurrence
2169of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done 2367of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done
2170synchronously as part of the event loop processing. Libev always reaps all 2368synchronously as part of the event loop processing. Libev always reaps all
2171children, even ones not watched. 2369children, even ones not watched.
2172.PP 2370.PP
2173\fIOverriding the Built-In Processing\fR 2371\fIOverriding the Built-In Processing\fR
… …
2185.IX Subsection "Stopping the Child Watcher" 2383.IX Subsection "Stopping the Child Watcher"
2186.PP 2384.PP
2187Currently, the child watcher never gets stopped, even when the 2385Currently, the child watcher never gets stopped, even when the
2188child terminates, so normally one needs to stop the watcher in the 2386child terminates, so normally one needs to stop the watcher in the
2189callback. Future versions of libev might stop the watcher automatically 2387callback. Future versions of libev might stop the watcher automatically
2190when a child exit is detected. 2388when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a
2389problem).
2191.PP 2390.PP
2192\fIWatcher-Specific Functions and Data Members\fR 2391\fIWatcher-Specific Functions and Data Members\fR
2193.IX Subsection "Watcher-Specific Functions and Data Members" 2392.IX Subsection "Watcher-Specific Functions and Data Members"
2194.IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 2393.IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4
2195.IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" 2394.IX Item "ev_child_init (ev_child *, callback, int pid, int trace)"
… …
2245\& { 2444\& {
2246\& ev_child_init (&cw, child_cb, pid, 0); 2445\& ev_child_init (&cw, child_cb, pid, 0);
2247\& ev_child_start (EV_DEFAULT_ &cw); 2446\& ev_child_start (EV_DEFAULT_ &cw);
2248\& } 2447\& }
2249.Ve 2448.Ve
2250.ie n .Sh """ev_stat"" \- did the file attributes just change?" 2449.ie n .SS """ev_stat"" \- did the file attributes just change?"
2251.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" 2450.el .SS "\f(CWev_stat\fP \- did the file attributes just change?"
2252.IX Subsection "ev_stat - did the file attributes just change?" 2451.IX Subsection "ev_stat - did the file attributes just change?"
2253This watches a file system path for attribute changes. That is, it calls 2452This watches a file system path for attribute changes. That is, it calls
2254\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) 2453\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed)
2255and sees if it changed compared to the last time, invoking the callback if 2454and sees if it changed compared to the last time, invoking the callback if
2256it did. 2455it did.
… …
2470\& ... 2669\& ...
2471\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); 2670\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
2472\& ev_stat_start (loop, &passwd); 2671\& ev_stat_start (loop, &passwd);
2473\& ev_timer_init (&timer, timer_cb, 0., 1.02); 2672\& ev_timer_init (&timer, timer_cb, 0., 1.02);
2474.Ve 2673.Ve
2475.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 2674.ie n .SS """ev_idle"" \- when you've got nothing better to do..."
2476.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 2675.el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..."
2477.IX Subsection "ev_idle - when you've got nothing better to do..." 2676.IX Subsection "ev_idle - when you've got nothing better to do..."
2478Idle watchers trigger events when no other events of the same or higher 2677Idle watchers trigger events when no other events of the same or higher
2479priority are pending (prepare, check and other idle watchers do not count 2678priority are pending (prepare, check and other idle watchers do not count
2480as receiving \*(L"events\*(R"). 2679as receiving \*(L"events\*(R").
2481.PP 2680.PP
… …
2517\& // no longer anything immediate to do. 2716\& // no longer anything immediate to do.
2518\& } 2717\& }
2519\& 2718\&
2520\& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); 2719\& ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2521\& ev_idle_init (idle_watcher, idle_cb); 2720\& ev_idle_init (idle_watcher, idle_cb);
2522\& ev_idle_start (loop, idle_cb); 2721\& ev_idle_start (loop, idle_watcher);
2523.Ve 2722.Ve
2524.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" 2723.ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!"
2525.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" 2724.el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
2526.IX Subsection "ev_prepare and ev_check - customise your event loop!" 2725.IX Subsection "ev_prepare and ev_check - customise your event loop!"
2527Prepare and check watchers are usually (but not always) used in pairs: 2726Prepare and check watchers are usually (but not always) used in pairs:
2528prepare watchers get invoked before the process blocks and check watchers 2727prepare watchers get invoked before the process blocks and check watchers
2529afterwards. 2728afterwards.
2530.PP 2729.PP
… …
2620\& struct pollfd fds [nfd]; 2819\& struct pollfd fds [nfd];
2621\& // actual code will need to loop here and realloc etc. 2820\& // actual code will need to loop here and realloc etc.
2622\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 2821\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2623\& 2822\&
2624\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ 2823\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */
2625\& ev_timer_init (&tw, 0, timeout * 1e\-3); 2824\& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.);
2626\& ev_timer_start (loop, &tw); 2825\& ev_timer_start (loop, &tw);
2627\& 2826\&
2628\& // create one ev_io per pollfd 2827\& // create one ev_io per pollfd
2629\& for (int i = 0; i < nfd; ++i) 2828\& for (int i = 0; i < nfd; ++i)
2630\& { 2829\& {
… …
2721\& ev_io_stop (EV_A_ iow [n]); 2920\& ev_io_stop (EV_A_ iow [n]);
2722\& 2921\&
2723\& return got_events; 2922\& return got_events;
2724\& } 2923\& }
2725.Ve 2924.Ve
2726.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 2925.ie n .SS """ev_embed"" \- when one backend isn't enough..."
2727.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 2926.el .SS "\f(CWev_embed\fP \- when one backend isn't enough..."
2728.IX Subsection "ev_embed - when one backend isn't enough..." 2927.IX Subsection "ev_embed - when one backend isn't enough..."
2729This is a rather advanced watcher type that lets you embed one event loop 2928This is a rather advanced watcher type that lets you embed one event loop
2730into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded 2929into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
2731loop, other types of watchers might be handled in a delayed or incorrect 2930loop, other types of watchers might be handled in a delayed or incorrect
2732fashion and must not be used). 2931fashion and must not be used).
… …
2854\& if (!loop_socket) 3053\& if (!loop_socket)
2855\& loop_socket = loop; 3054\& loop_socket = loop;
2856\& 3055\&
2857\& // now use loop_socket for all sockets, and loop for everything else 3056\& // now use loop_socket for all sockets, and loop for everything else
2858.Ve 3057.Ve
2859.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 3058.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork"
2860.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 3059.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
2861.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 3060.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
2862Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 3061Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
2863whoever is a good citizen cared to tell libev about it by calling 3062whoever is a good citizen cared to tell libev about it by calling
2864\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 3063\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
2865event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 3064event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
… …
2906.IP "ev_fork_init (ev_signal *, callback)" 4 3105.IP "ev_fork_init (ev_signal *, callback)" 4
2907.IX Item "ev_fork_init (ev_signal *, callback)" 3106.IX Item "ev_fork_init (ev_signal *, callback)"
2908Initialises and configures the fork watcher \- it has no parameters of any 3107Initialises and configures the fork watcher \- it has no parameters of any
2909kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 3108kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
2910believe me. 3109believe me.
2911.ie n .Sh """ev_async"" \- how to wake up another event loop" 3110.ie n .SS """ev_async"" \- how to wake up another event loop"
2912.el .Sh "\f(CWev_async\fP \- how to wake up another event loop" 3111.el .SS "\f(CWev_async\fP \- how to wake up another event loop"
2913.IX Subsection "ev_async - how to wake up another event loop" 3112.IX Subsection "ev_async - how to wake up another event loop"
2914In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other 3113In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other
2915asynchronous sources such as signal handlers (as opposed to multiple event 3114asynchronous sources such as signal handlers (as opposed to multiple event
2916loops \- those are of course safe to use in different threads). 3115loops \- those are of course safe to use in different threads).
2917.PP 3116.PP
… …
2933.IX Subsection "Queueing" 3132.IX Subsection "Queueing"
2934.PP 3133.PP
2935\&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason 3134\&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason
2936is that the author does not know of a simple (or any) algorithm for a 3135is that the author does not know of a simple (or any) algorithm for a
2937multiple-writer-single-reader queue that works in all cases and doesn't 3136multiple-writer-single-reader queue that works in all cases and doesn't
2938need elaborate support such as pthreads. 3137need elaborate support such as pthreads or unportable memory access
3138semantics.
2939.PP 3139.PP
2940That means that if you want to queue data, you have to provide your own 3140That means that if you want to queue data, you have to provide your own
2941queue. But at least I can tell you how to implement locking around your 3141queue. But at least I can tell you how to implement locking around your
2942queue: 3142queue:
2943.IP "queueing from a signal handler context" 4 3143.IP "queueing from a signal handler context" 4
… …
3088\& /* doh, nothing entered */; 3288\& /* doh, nothing entered */;
3089\& } 3289\& }
3090\& 3290\&
3091\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 3291\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3092.Ve 3292.Ve
3093.IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4
3094.IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)"
3095Feeds the given event set into the event loop, as if the specified event
3096had happened for the specified watcher (which must be a pointer to an
3097initialised but not necessarily started event watcher).
3098.IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 3293.IP "ev_feed_fd_event (loop, int fd, int revents)" 4
3099.IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 3294.IX Item "ev_feed_fd_event (loop, int fd, int revents)"
3100Feed an event on the given fd, as if a file descriptor backend detected 3295Feed an event on the given fd, as if a file descriptor backend detected
3101the given events it. 3296the given events it.
3102.IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 3297.IP "ev_feed_signal_event (loop, int signum)" 4
3103.IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" 3298.IX Item "ev_feed_signal_event (loop, int signum)"
3104Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default 3299Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default
3105loop!). 3300loop!).
3106.SH "LIBEVENT EMULATION" 3301.SH "LIBEVENT EMULATION"
3107.IX Header "LIBEVENT EMULATION" 3302.IX Header "LIBEVENT EMULATION"
3108Libev offers a compatibility emulation layer for libevent. It cannot 3303Libev offers a compatibility emulation layer for libevent. It cannot
… …
3155need one additional pointer for context. If you need support for other 3350need one additional pointer for context. If you need support for other
3156types of functors please contact the author (preferably after implementing 3351types of functors please contact the author (preferably after implementing
3157it). 3352it).
3158.PP 3353.PP
3159Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 3354Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
3160.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 3355.ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4
3161.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 3356.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
3162.IX Item "ev::READ, ev::WRITE etc." 3357.IX Item "ev::READ, ev::WRITE etc."
3163These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. 3358These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
3164macros from \fIev.h\fR. 3359macros from \fIev.h\fR.
3165.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 3360.ie n .IP """ev::tstamp"", ""ev::now""" 4
3166.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 3361.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
3167.IX Item "ev::tstamp, ev::now" 3362.IX Item "ev::tstamp, ev::now"
3168Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. 3363Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
3169.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 3364.ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4
3170.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 3365.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
3171.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." 3366.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
3172For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of 3367For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
3173the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR 3368the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
3174which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 3369which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
… …
3177All of those classes have these methods: 3372All of those classes have these methods:
3178.RS 4 3373.RS 4
3179.IP "ev::TYPE::TYPE ()" 4 3374.IP "ev::TYPE::TYPE ()" 4
3180.IX Item "ev::TYPE::TYPE ()" 3375.IX Item "ev::TYPE::TYPE ()"
3181.PD 0 3376.PD 0
3182.IP "ev::TYPE::TYPE (struct ev_loop *)" 4 3377.IP "ev::TYPE::TYPE (loop)" 4
3183.IX Item "ev::TYPE::TYPE (struct ev_loop *)" 3378.IX Item "ev::TYPE::TYPE (loop)"
3184.IP "ev::TYPE::~TYPE" 4 3379.IP "ev::TYPE::~TYPE" 4
3185.IX Item "ev::TYPE::~TYPE" 3380.IX Item "ev::TYPE::~TYPE"
3186.PD 3381.PD
3187The constructor (optionally) takes an event loop to associate the watcher 3382The constructor (optionally) takes an event loop to associate the watcher
3188with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. 3383with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
… …
3267.Sp 3462.Sp
3268.Vb 2 3463.Vb 2
3269\& static void io_cb (ev::io &w, int revents) { } 3464\& static void io_cb (ev::io &w, int revents) { }
3270\& iow.set <io_cb> (); 3465\& iow.set <io_cb> ();
3271.Ve 3466.Ve
3272.IP "w\->set (struct ev_loop *)" 4 3467.IP "w\->set (loop)" 4
3273.IX Item "w->set (struct ev_loop *)" 3468.IX Item "w->set (loop)"
3274Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 3469Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
3275do this when the watcher is inactive (and not pending either). 3470do this when the watcher is inactive (and not pending either).
3276.IP "w\->set ([arguments])" 4 3471.IP "w\->set ([arguments])" 4
3277.IX Item "w->set ([arguments])" 3472.IX Item "w->set ([arguments])"
3278Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be 3473Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be
… …
3284Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the 3479Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
3285constructor already stores the event loop. 3480constructor already stores the event loop.
3286.IP "w\->stop ()" 4 3481.IP "w\->stop ()" 4
3287.IX Item "w->stop ()" 3482.IX Item "w->stop ()"
3288Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 3483Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
3289.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 3484.ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4
3290.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 3485.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
3291.IX Item "w->again () (ev::timer, ev::periodic only)" 3486.IX Item "w->again () (ev::timer, ev::periodic only)"
3292For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding 3487For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
3293\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 3488\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
3294.ie n .IP "w\->sweep () (""ev::embed"" only)" 4 3489.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
… …
3361be found at <http://proj.llucax.com.ar/wiki/evd>. 3556be found at <http://proj.llucax.com.ar/wiki/evd>.
3362.IP "Ocaml" 4 3557.IP "Ocaml" 4
3363.IX Item "Ocaml" 3558.IX Item "Ocaml"
3364Erkki Seppala has written Ocaml bindings for libev, to be found at 3559Erkki Seppala has written Ocaml bindings for libev, to be found at
3365<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. 3560<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>.
3561.IP "Lua" 4
3562.IX Item "Lua"
3563Brian Maher has written a partial interface to libev
3564for lua (only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at
3565<http://github.com/brimworks/lua\-ev>.
3366.SH "MACRO MAGIC" 3566.SH "MACRO MAGIC"
3367.IX Header "MACRO MAGIC" 3567.IX Header "MACRO MAGIC"
3368Libev can be compiled with a variety of options, the most fundamental 3568Libev can be compiled with a variety of options, the most fundamental
3369of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 3569of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
3370functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 3570functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
3371.PP 3571.PP
3372To make it easier to write programs that cope with either variant, the 3572To make it easier to write programs that cope with either variant, the
3373following macros are defined: 3573following macros are defined:
3374.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 3574.ie n .IP """EV_A"", ""EV_A_""" 4
3375.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 3575.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
3376.IX Item "EV_A, EV_A_" 3576.IX Item "EV_A, EV_A_"
3377This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev 3577This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
3378loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, 3578loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
3379\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: 3579\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
… …
3384\& ev_loop (EV_A_ 0); 3584\& ev_loop (EV_A_ 0);
3385.Ve 3585.Ve
3386.Sp 3586.Sp
3387It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, 3587It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
3388which is often provided by the following macro. 3588which is often provided by the following macro.
3389.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 3589.ie n .IP """EV_P"", ""EV_P_""" 4
3390.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 3590.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
3391.IX Item "EV_P, EV_P_" 3591.IX Item "EV_P, EV_P_"
3392This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev 3592This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
3393loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, 3593loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
3394\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: 3594\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
… …
3401\& static void cb (EV_P_ ev_timer *w, int revents) 3601\& static void cb (EV_P_ ev_timer *w, int revents)
3402.Ve 3602.Ve
3403.Sp 3603.Sp
3404It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite 3604It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
3405suitable for use with \f(CW\*(C`EV_A\*(C'\fR. 3605suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
3406.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 3606.ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4
3407.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 3607.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
3408.IX Item "EV_DEFAULT, EV_DEFAULT_" 3608.IX Item "EV_DEFAULT, EV_DEFAULT_"
3409Similar to the other two macros, this gives you the value of the default 3609Similar to the other two macros, this gives you the value of the default
3410loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 3610loop, if multiple loops are supported (\*(L"ev loop default\*(R").
3411.ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 3611.ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4
3412.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 3612.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4
3413.IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" 3613.IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_"
3414Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the 3614Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the
3415default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour 3615default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour
3416is undefined when the default loop has not been initialised by a previous 3616is undefined when the default loop has not been initialised by a previous
… …
3444.PP 3644.PP
3445The goal is to enable you to just copy the necessary files into your 3645The goal is to enable you to just copy the necessary files into your
3446source directory without having to change even a single line in them, so 3646source directory without having to change even a single line in them, so
3447you can easily upgrade by simply copying (or having a checked-out copy of 3647you can easily upgrade by simply copying (or having a checked-out copy of
3448libev somewhere in your source tree). 3648libev somewhere in your source tree).
3449.Sh "\s-1FILESETS\s0" 3649.SS "\s-1FILESETS\s0"
3450.IX Subsection "FILESETS" 3650.IX Subsection "FILESETS"
3451Depending on what features you need you need to include one or more sets of files 3651Depending on what features you need you need to include one or more sets of files
3452in your application. 3652in your application.
3453.PP 3653.PP
3454\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 3654\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
… …
3533For this of course you need the m4 file: 3733For this of course you need the m4 file:
3534.PP 3734.PP
3535.Vb 1 3735.Vb 1
3536\& libev.m4 3736\& libev.m4
3537.Ve 3737.Ve
3538.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 3738.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
3539.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 3739.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
3540Libev can be configured via a variety of preprocessor symbols you have to 3740Libev can be configured via a variety of preprocessor symbols you have to
3541define before including any of its files. The default in the absence of 3741define before including any of its files. The default in the absence of
3542autoconf is documented for every option. 3742autoconf is documented for every option.
3543.IP "\s-1EV_STANDALONE\s0" 4 3743.IP "\s-1EV_STANDALONE\s0" 4
… …
3546keeps libev from including \fIconfig.h\fR, and it also defines dummy 3746keeps libev from including \fIconfig.h\fR, and it also defines dummy
3547implementations for some libevent functions (such as logging, which is not 3747implementations for some libevent functions (such as logging, which is not
3548supported). It will also not define any of the structs usually found in 3748supported). It will also not define any of the structs usually found in
3549\&\fIevent.h\fR that are not directly supported by the libev core alone. 3749\&\fIevent.h\fR that are not directly supported by the libev core alone.
3550.Sp 3750.Sp
3551In stanbdalone mode, libev will still try to automatically deduce the 3751In standalone mode, libev will still try to automatically deduce the
3552configuration, but has to be more conservative. 3752configuration, but has to be more conservative.
3553.IP "\s-1EV_USE_MONOTONIC\s0" 4 3753.IP "\s-1EV_USE_MONOTONIC\s0" 4
3554.IX Item "EV_USE_MONOTONIC" 3754.IX Item "EV_USE_MONOTONIC"
3555If defined to be \f(CW1\fR, libev will try to detect the availability of the 3755If defined to be \f(CW1\fR, libev will try to detect the availability of the
3556monotonic clock option at both compile time and runtime. Otherwise no 3756monotonic clock option at both compile time and runtime. Otherwise no
… …
3612wants osf handles on win32 (this is the case when the select to 3812wants osf handles on win32 (this is the case when the select to
3613be used is the winsock select). This means that it will call 3813be used is the winsock select). This means that it will call
3614\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, 3814\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
3615it is assumed that all these functions actually work on fds, even 3815it is assumed that all these functions actually work on fds, even
3616on win32. Should not be defined on non\-win32 platforms. 3816on win32. Should not be defined on non\-win32 platforms.
3617.IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 3817.IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4
3618.IX Item "EV_FD_TO_WIN32_HANDLE" 3818.IX Item "EV_FD_TO_WIN32_HANDLE(fd)"
3619If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map 3819If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map
3620file descriptors to socket handles. When not defining this symbol (the 3820file descriptors to socket handles. When not defining this symbol (the
3621default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually 3821default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually
3622correct. In some cases, programs use their own file descriptor management, 3822correct. In some cases, programs use their own file descriptor management,
3623in which case they can provide this function to map fds to socket handles. 3823in which case they can provide this function to map fds to socket handles.
3824.IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4
3825.IX Item "EV_WIN32_HANDLE_TO_FD(handle)"
3826If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors
3827using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing
3828their own fd to handle mapping, overwriting this function makes it easier
3829to do so. This can be done by defining this macro to an appropriate value.
3830.IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4
3831.IX Item "EV_WIN32_CLOSE_FD(fd)"
3832If programs implement their own fd to handle mapping on win32, then this
3833macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister
3834file descriptors again. Note that the replacement function has to close
3835the underlying \s-1OS\s0 handle.
3624.IP "\s-1EV_USE_POLL\s0" 4 3836.IP "\s-1EV_USE_POLL\s0" 4
3625.IX Item "EV_USE_POLL" 3837.IX Item "EV_USE_POLL"
3626If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) 3838If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
3627backend. Otherwise it will be enabled on non\-win32 platforms. It 3839backend. Otherwise it will be enabled on non\-win32 platforms. It
3628takes precedence over select. 3840takes precedence over select.
… …
3742If undefined or defined to be \f(CW1\fR, then async watchers are supported. If 3954If undefined or defined to be \f(CW1\fR, then async watchers are supported. If
3743defined to be \f(CW0\fR, then they are not. 3955defined to be \f(CW0\fR, then they are not.
3744.IP "\s-1EV_MINIMAL\s0" 4 3956.IP "\s-1EV_MINIMAL\s0" 4
3745.IX Item "EV_MINIMAL" 3957.IX Item "EV_MINIMAL"
3746If you need to shave off some kilobytes of code at the expense of some 3958If you need to shave off some kilobytes of code at the expense of some
3747speed, define this symbol to \f(CW1\fR. Currently this is used to override some 3959speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this
3748inlining decisions, saves roughly 30% code size on amd64. It also selects a 3960is used to override some inlining decisions, saves roughly 30% code size
3749much smaller 2\-heap for timer management over the default 4\-heap. 3961on amd64. It also selects a much smaller 2\-heap for timer management over
3962the default 4\-heap.
3963.Sp
3964You can save even more by disabling watcher types you do not need
3965and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR
3966(\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot.
3967.Sp
3968Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to
3969provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts
3970of the \s-1API\s0 are still available, and do not complain if this subset changes
3971over time.
3972.IP "\s-1EV_NSIG\s0" 4
3973.IX Item "EV_NSIG"
3974The highest supported signal number, +1 (or, the number of
3975signals): Normally, libev tries to deduce the maximum number of signals
3976automatically, but sometimes this fails, in which case it can be
3977specified. Also, using a lower number than detected (\f(CW32\fR should be
3978good for about any system in existance) can save some memory, as libev
3979statically allocates some 12\-24 bytes per signal number.
3750.IP "\s-1EV_PID_HASHSIZE\s0" 4 3980.IP "\s-1EV_PID_HASHSIZE\s0" 4
3751.IX Item "EV_PID_HASHSIZE" 3981.IX Item "EV_PID_HASHSIZE"
3752\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 3982\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
3753pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 3983pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
3754than enough. If you need to manage thousands of children you might want to 3984than enough. If you need to manage thousands of children you might want to
… …
3818and the way callbacks are invoked and set. Must expand to a struct member 4048and the way callbacks are invoked and set. Must expand to a struct member
3819definition and a statement, respectively. See the \fIev.h\fR header file for 4049definition and a statement, respectively. See the \fIev.h\fR header file for
3820their default definitions. One possible use for overriding these is to 4050their default definitions. One possible use for overriding these is to
3821avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 4051avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
3822method calls instead of plain function calls in \*(C+. 4052method calls instead of plain function calls in \*(C+.
3823.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 4053.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
3824.IX Subsection "EXPORTED API SYMBOLS" 4054.IX Subsection "EXPORTED API SYMBOLS"
3825If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of 4055If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of
3826exported symbols, you can use the provided \fISymbol.*\fR files which list 4056exported symbols, you can use the provided \fISymbol.*\fR files which list
3827all public symbols, one per line: 4057all public symbols, one per line:
3828.PP 4058.PP
… …
3848\& #define ev_backend myprefix_ev_backend 4078\& #define ev_backend myprefix_ev_backend
3849\& #define ev_check_start myprefix_ev_check_start 4079\& #define ev_check_start myprefix_ev_check_start
3850\& #define ev_check_stop myprefix_ev_check_stop 4080\& #define ev_check_stop myprefix_ev_check_stop
3851\& ... 4081\& ...
3852.Ve 4082.Ve
3853.Sh "\s-1EXAMPLES\s0" 4083.SS "\s-1EXAMPLES\s0"
3854.IX Subsection "EXAMPLES" 4084.IX Subsection "EXAMPLES"
3855For a real-world example of a program the includes libev 4085For a real-world example of a program the includes libev
3856verbatim, you can have a look at the \s-1EV\s0 perl module 4086verbatim, you can have a look at the \s-1EV\s0 perl module
3857(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 4087(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
3858the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public 4088the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
… …
3883\& #include "ev_cpp.h" 4113\& #include "ev_cpp.h"
3884\& #include "ev.c" 4114\& #include "ev.c"
3885.Ve 4115.Ve
3886.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4116.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3887.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4117.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3888.Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 4118.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0"
3889.IX Subsection "THREADS AND COROUTINES" 4119.IX Subsection "THREADS AND COROUTINES"
3890\fI\s-1THREADS\s0\fR 4120\fI\s-1THREADS\s0\fR
3891.IX Subsection "THREADS" 4121.IX Subsection "THREADS"
3892.PP 4122.PP
3893All libev functions are reentrant and thread-safe unless explicitly 4123All libev functions are reentrant and thread-safe unless explicitly
… …
3939An example use would be to communicate signals or other events that only 4169An example use would be to communicate signals or other events that only
3940work in the default loop by registering the signal watcher with the 4170work in the default loop by registering the signal watcher with the
3941default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop 4171default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop
3942watcher callback into the event loop interested in the signal. 4172watcher callback into the event loop interested in the signal.
3943.PP 4173.PP
4174\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0
4175.IX Subsection "THREAD LOCKING EXAMPLE"
4176.PP
4177Here is a fictitious example of how to run an event loop in a different
4178thread than where callbacks are being invoked and watchers are
4179created/added/removed.
4180.PP
4181For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module,
4182which uses exactly this technique (which is suited for many high-level
4183languages).
4184.PP
4185The example uses a pthread mutex to protect the loop data, a condition
4186variable to wait for callback invocations, an async watcher to notify the
4187event loop thread and an unspecified mechanism to wake up the main thread.
4188.PP
4189First, you need to associate some data with the event loop:
4190.PP
4191.Vb 6
4192\& typedef struct {
4193\& mutex_t lock; /* global loop lock */
4194\& ev_async async_w;
4195\& thread_t tid;
4196\& cond_t invoke_cv;
4197\& } userdata;
4198\&
4199\& void prepare_loop (EV_P)
4200\& {
4201\& // for simplicity, we use a static userdata struct.
4202\& static userdata u;
4203\&
4204\& ev_async_init (&u\->async_w, async_cb);
4205\& ev_async_start (EV_A_ &u\->async_w);
4206\&
4207\& pthread_mutex_init (&u\->lock, 0);
4208\& pthread_cond_init (&u\->invoke_cv, 0);
4209\&
4210\& // now associate this with the loop
4211\& ev_set_userdata (EV_A_ u);
4212\& ev_set_invoke_pending_cb (EV_A_ l_invoke);
4213\& ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4214\&
4215\& // then create the thread running ev_loop
4216\& pthread_create (&u\->tid, 0, l_run, EV_A);
4217\& }
4218.Ve
4219.PP
4220The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used
4221solely to wake up the event loop so it takes notice of any new watchers
4222that might have been added:
4223.PP
4224.Vb 5
4225\& static void
4226\& async_cb (EV_P_ ev_async *w, int revents)
4227\& {
4228\& // just used for the side effects
4229\& }
4230.Ve
4231.PP
4232The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex
4233protecting the loop data, respectively.
4234.PP
4235.Vb 6
4236\& static void
4237\& l_release (EV_P)
4238\& {
4239\& userdata *u = ev_userdata (EV_A);
4240\& pthread_mutex_unlock (&u\->lock);
4241\& }
4242\&
4243\& static void
4244\& l_acquire (EV_P)
4245\& {
4246\& userdata *u = ev_userdata (EV_A);
4247\& pthread_mutex_lock (&u\->lock);
4248\& }
4249.Ve
4250.PP
4251The event loop thread first acquires the mutex, and then jumps straight
4252into \f(CW\*(C`ev_loop\*(C'\fR:
4253.PP
4254.Vb 4
4255\& void *
4256\& l_run (void *thr_arg)
4257\& {
4258\& struct ev_loop *loop = (struct ev_loop *)thr_arg;
4259\&
4260\& l_acquire (EV_A);
4261\& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4262\& ev_loop (EV_A_ 0);
4263\& l_release (EV_A);
4264\&
4265\& return 0;
4266\& }
4267.Ve
4268.PP
4269Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will
4270signal the main thread via some unspecified mechanism (signals? pipe
4271writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers
4272have been called (in a while loop because a) spurious wakeups are possible
4273and b) skipping inter-thread-communication when there are no pending
4274watchers is very beneficial):
4275.PP
4276.Vb 4
4277\& static void
4278\& l_invoke (EV_P)
4279\& {
4280\& userdata *u = ev_userdata (EV_A);
4281\&
4282\& while (ev_pending_count (EV_A))
4283\& {
4284\& wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4285\& pthread_cond_wait (&u\->invoke_cv, &u\->lock);
4286\& }
4287\& }
4288.Ve
4289.PP
4290Now, whenever the main thread gets told to invoke pending watchers, it
4291will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop
4292thread to continue:
4293.PP
4294.Vb 4
4295\& static void
4296\& real_invoke_pending (EV_P)
4297\& {
4298\& userdata *u = ev_userdata (EV_A);
4299\&
4300\& pthread_mutex_lock (&u\->lock);
4301\& ev_invoke_pending (EV_A);
4302\& pthread_cond_signal (&u\->invoke_cv);
4303\& pthread_mutex_unlock (&u\->lock);
4304\& }
4305.Ve
4306.PP
4307Whenever you want to start/stop a watcher or do other modifications to an
4308event loop, you will now have to lock:
4309.PP
4310.Vb 2
4311\& ev_timer timeout_watcher;
4312\& userdata *u = ev_userdata (EV_A);
4313\&
4314\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4315\&
4316\& pthread_mutex_lock (&u\->lock);
4317\& ev_timer_start (EV_A_ &timeout_watcher);
4318\& ev_async_send (EV_A_ &u\->async_w);
4319\& pthread_mutex_unlock (&u\->lock);
4320.Ve
4321.PP
4322Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
4323an event loop currently blocking in the kernel will have no knowledge
4324about the newly added timer. By waking up the loop it will pick up any new
4325watchers in the next event loop iteration.
4326.PP
3944\fI\s-1COROUTINES\s0\fR 4327\fI\s-1COROUTINES\s0\fR
3945.IX Subsection "COROUTINES" 4328.IX Subsection "COROUTINES"
3946.PP 4329.PP
3947Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 4330Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
3948libev fully supports nesting calls to its functions from different 4331libev fully supports nesting calls to its functions from different
3949coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two 4332coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two
3950different coroutines, and switch freely between both coroutines running the 4333different coroutines, and switch freely between both coroutines running
3951loop, as long as you don't confuse yourself). The only exception is that 4334the loop, as long as you don't confuse yourself). The only exception is
3952you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 4335that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
3953.PP 4336.PP
3954Care has been taken to ensure that libev does not keep local state inside 4337Care has been taken to ensure that libev does not keep local state inside
3955\&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as 4338\&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as
3956they do not call any callbacks. 4339they do not call any callbacks.
3957.Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" 4340.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0"
3958.IX Subsection "COMPILER WARNINGS" 4341.IX Subsection "COMPILER WARNINGS"
3959Depending on your compiler and compiler settings, you might get no or a 4342Depending on your compiler and compiler settings, you might get no or a
3960lot of warnings when compiling libev code. Some people are apparently 4343lot of warnings when compiling libev code. Some people are apparently
3961scared by this. 4344scared by this.
3962.PP 4345.PP
… …
3979While libev is written to generate as few warnings as possible, 4362While libev is written to generate as few warnings as possible,
3980\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev 4363\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev
3981with any compiler warnings enabled unless you are prepared to cope with 4364with any compiler warnings enabled unless you are prepared to cope with
3982them (e.g. by ignoring them). Remember that warnings are just that: 4365them (e.g. by ignoring them). Remember that warnings are just that:
3983warnings, not errors, or proof of bugs. 4366warnings, not errors, or proof of bugs.
3984.Sh "\s-1VALGRIND\s0" 4367.SS "\s-1VALGRIND\s0"
3985.IX Subsection "VALGRIND" 4368.IX Subsection "VALGRIND"
3986Valgrind has a special section here because it is a popular tool that is 4369Valgrind has a special section here because it is a popular tool that is
3987highly useful. Unfortunately, valgrind reports are very hard to interpret. 4370highly useful. Unfortunately, valgrind reports are very hard to interpret.
3988.PP 4371.PP
3989If you think you found a bug (memory leak, uninitialised data access etc.) 4372If you think you found a bug (memory leak, uninitialised data access etc.)
… …
4014.PP 4397.PP
4015If you need, for some reason, empty reports from valgrind for your project 4398If you need, for some reason, empty reports from valgrind for your project
4016I suggest using suppression lists. 4399I suggest using suppression lists.
4017.SH "PORTABILITY NOTES" 4400.SH "PORTABILITY NOTES"
4018.IX Header "PORTABILITY NOTES" 4401.IX Header "PORTABILITY NOTES"
4019.Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 4402.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0"
4020.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 4403.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
4021Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 4404Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
4022requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 4405requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0
4023model. Libev still offers limited functionality on this platform in 4406model. Libev still offers limited functionality on this platform in
4024the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket 4407the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket
… …
4111(another arbitrary limit), but is broken in many versions of the Microsoft 4494(another arbitrary limit), but is broken in many versions of the Microsoft
4112runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets 4495runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets
4113(depending on windows version and/or the phase of the moon). To get more, 4496(depending on windows version and/or the phase of the moon). To get more,
4114you need to wrap all I/O functions and provide your own fd management, but 4497you need to wrap all I/O functions and provide your own fd management, but
4115the cost of calling select (O(nA\*^X)) will likely make this unworkable. 4498the cost of calling select (O(nA\*^X)) will likely make this unworkable.
4116.Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 4499.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0"
4117.IX Subsection "PORTABILITY REQUIREMENTS" 4500.IX Subsection "PORTABILITY REQUIREMENTS"
4118In addition to a working ISO-C implementation and of course the 4501In addition to a working ISO-C implementation and of course the
4119backend-specific APIs, libev relies on a few additional extensions: 4502backend-specific APIs, libev relies on a few additional extensions:
4120.ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 4503.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4
4121.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 4504.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
4122.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." 4505.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
4123Libev assumes not only that all watcher pointers have the same internal 4506Libev assumes not only that all watcher pointers have the same internal
4124structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also 4507structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also
4125assumes that the same (machine) code can be used to call any watcher 4508assumes that the same (machine) code can be used to call any watcher
… …
4157.el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 4540.el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4
4158.IX Item "double must hold a time value in seconds with enough accuracy" 4541.IX Item "double must hold a time value in seconds with enough accuracy"
4159The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to 4542The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to
4160have at least 51 bits of mantissa (and 9 bits of exponent), which is good 4543have at least 51 bits of mantissa (and 9 bits of exponent), which is good
4161enough for at least into the year 4000. This requirement is fulfilled by 4544enough for at least into the year 4000. This requirement is fulfilled by
4162implementations implementing \s-1IEEE\s0 754 (basically all existing ones). 4545implementations implementing \s-1IEEE\s0 754, which is basically all existing
4546ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least
45472200.
4163.PP 4548.PP
4164If you know of other additional requirements drop me a note. 4549If you know of other additional requirements drop me a note.
4165.SH "ALGORITHMIC COMPLEXITIES" 4550.SH "ALGORITHMIC COMPLEXITIES"
4166.IX Header "ALGORITHMIC COMPLEXITIES" 4551.IX Header "ALGORITHMIC COMPLEXITIES"
4167In this section the complexities of (many of) the algorithms used inside 4552In this section the complexities of (many of) the algorithms used inside

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