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Revision 1.106 by root, Wed Nov 16 17:39:52 2016 UTC vs.
Revision 1.109 by root, Fri Dec 21 07:03:02 2018 UTC

1.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.30) 1.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.29)
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3.\" Standard preamble: 3.\" Standard preamble:
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131.\} 131.\}
132.rm #[ #] #H #V #F C 132.rm #[ #] #H #V #F C
133.\" ======================================================================== 133.\" ========================================================================
134.\" 134.\"
135.IX Title "LIBEV 3" 135.IX Title "LIBEV 3"
136.TH LIBEV 3 "2016-11-16" "libev-4.23" "libev - high performance full featured event loop" 136.TH LIBEV 3 "2018-12-21" "libev-4.25" "libev - high performance full featured event loop"
137.\" For nroff, turn off justification. Always turn off hyphenation; it makes 137.\" For nroff, turn off justification. Always turn off hyphenation; it makes
138.\" way too many mistakes in technical documents. 138.\" way too many mistakes in technical documents.
139.if n .ad l 139.if n .ad l
140.nh 140.nh
141.SH "NAME" 141.SH "NAME"
… …
536make libev check for a fork in each iteration by enabling this flag. 536make libev check for a fork in each iteration by enabling this flag.
537.Sp 537.Sp
538This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, 538This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
539and thus this might slow down your event loop if you do a lot of loop 539and thus this might slow down your event loop if you do a lot of loop
540iterations and little real work, but is usually not noticeable (on my 540iterations and little real work, but is usually not noticeable (on my
541GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence 541GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn
542without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has 542sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux
543\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). 543system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc
544versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again).
544.Sp 545.Sp
545The big advantage of this flag is that you can forget about fork (and 546The big advantage of this flag is that you can forget about fork (and
546forget about forgetting to tell libev about forking, although you still 547forget about forgetting to tell libev about forking, although you still
547have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. 548have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag.
548.Sp 549.Sp
… …
2250.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 2251.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
2251.PD 0 2252.PD 0
2252.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 2253.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
2253.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 2254.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
2254.PD 2255.PD
2255Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR 2256Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and
2256is \f(CW0.\fR, then it will automatically be stopped once the timeout is 2257negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will
2257reached. If it is positive, then the timer will automatically be 2258automatically be stopped once the timeout is reached. If it is positive,
2258configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, 2259then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR
2259until stopped manually. 2260seconds later, again, and again, until stopped manually.
2260.Sp 2261.Sp
2261The timer itself will do a best-effort at avoiding drift, that is, if 2262The timer itself will do a best-effort at avoiding drift, that is, if
2262you configure a timer to trigger every 10 seconds, then it will normally 2263you configure a timer to trigger every 10 seconds, then it will normally
2263trigger at exactly 10 second intervals. If, however, your program cannot 2264trigger at exactly 10 second intervals. If, however, your program cannot
2264keep up with the timer (because it takes longer than those 10 seconds to 2265keep up with the timer (because it takes longer than those 10 seconds to
… …
2361\&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting 2362\&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting
2362it, as it uses a relative timeout). 2363it, as it uses a relative timeout).
2363.PP 2364.PP
2364\&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex 2365\&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex
2365timers, such as triggering an event on each \*(L"midnight, local time\*(R", or 2366timers, such as triggering an event on each \*(L"midnight, local time\*(R", or
2366other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as 2367other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR
2367those cannot react to time jumps. 2368watchers, as those cannot react to time jumps.
2368.PP 2369.PP
2369As with timers, the callback is guaranteed to be invoked only when the 2370As with timers, the callback is guaranteed to be invoked only when the
2370point in time where it is supposed to trigger has passed. If multiple 2371point in time where it is supposed to trigger has passed. If multiple
2371timers become ready during the same loop iteration then the ones with 2372timers become ready during the same loop iteration then the ones with
2372earlier time-out values are invoked before ones with later time-out values 2373earlier time-out values are invoked before ones with later time-out values
… …
2461.Sp 2462.Sp
2462\&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or 2463\&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or
2463equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. 2464equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
2464.Sp 2465.Sp
2465This can be used to create very complex timers, such as a timer that 2466This can be used to create very complex timers, such as a timer that
2466triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the 2467triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate
2467next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How 2468the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for
2468you do this is, again, up to you (but it is not trivial, which is the main 2469this. Here is a (completely untested, no error checking) example on how to
2469reason I omitted it as an example). 2470do this:
2471.Sp
2472.Vb 1
2473\& #include <time.h>
2474\&
2475\& static ev_tstamp
2476\& my_rescheduler (ev_periodic *w, ev_tstamp now)
2477\& {
2478\& time_t tnow = (time_t)now;
2479\& struct tm tm;
2480\& localtime_r (&tnow, &tm);
2481\&
2482\& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day
2483\& ++tm.tm_mday; // midnight next day
2484\&
2485\& return mktime (&tm);
2486\& }
2487.Ve
2488.Sp
2489Note: this code might run into trouble on days that have more then two
2490midnights (beginning and end).
2470.RE 2491.RE
2471.RS 4 2492.RS 4
2472.RE 2493.RE
2473.IP "ev_periodic_again (loop, ev_periodic *)" 4 2494.IP "ev_periodic_again (loop, ev_periodic *)" 4
2474.IX Item "ev_periodic_again (loop, ev_periodic *)" 2495.IX Item "ev_periodic_again (loop, ev_periodic *)"
… …
3644is a time window between the event loop checking and resetting the async 3665is a time window between the event loop checking and resetting the async
3645notification, and the callback being invoked. 3666notification, and the callback being invoked.
3646.SH "OTHER FUNCTIONS" 3667.SH "OTHER FUNCTIONS"
3647.IX Header "OTHER FUNCTIONS" 3668.IX Header "OTHER FUNCTIONS"
3648There are some other functions of possible interest. Described. Here. Now. 3669There are some other functions of possible interest. Described. Here. Now.
3649.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 3670.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4
3650.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 3671.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)"
3651This function combines a simple timer and an I/O watcher, calls your 3672This function combines a simple timer and an I/O watcher, calls your
3652callback on whichever event happens first and automatically stops both 3673callback on whichever event happens first and automatically stops both
3653watchers. This is useful if you want to wait for a single event on an fd 3674watchers. This is useful if you want to wait for a single event on an fd
3654or timeout without having to allocate/configure/start/stop/free one or 3675or timeout without having to allocate/configure/start/stop/free one or
3655more watchers yourself. 3676more watchers yourself.
… …
4105The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the 4126The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the
4106libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 4127libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0
4107will work fine. 4128will work fine.
4108.PP 4129.PP
4109Proper exception specifications might have to be added to callbacks passed 4130Proper exception specifications might have to be added to callbacks passed
4110to libev: exceptions may be thrown only from watcher callbacks, all 4131to libev: exceptions may be thrown only from watcher callbacks, all other
4111other callbacks (allocator, syserr, loop acquire/release and periodic 4132callbacks (allocator, syserr, loop acquire/release and periodic reschedule
4112reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw 4133callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR
4113()\*(C'\fR specification. If you have code that needs to be compiled as both C 4134specification. If you have code that needs to be compiled as both C and
4114and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: 4135\&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this:
4115.PP 4136.PP
4116.Vb 6 4137.Vb 6
4117\& static void 4138\& static void
4118\& fatal_error (const char *msg) EV_THROW 4139\& fatal_error (const char *msg) EV_NOEXCEPT
4119\& { 4140\& {
4120\& perror (msg); 4141\& perror (msg);
4121\& abort (); 4142\& abort ();
4122\& } 4143\& }
4123\& 4144\&
… …
4521\& ev_vars.h 4542\& ev_vars.h
4522\& ev_wrap.h 4543\& ev_wrap.h
4523\& 4544\&
4524\& ev_win32.c required on win32 platforms only 4545\& ev_win32.c required on win32 platforms only
4525\& 4546\&
4526\& ev_select.c only when select backend is enabled (which is enabled by default) 4547\& ev_select.c only when select backend is enabled
4527\& ev_poll.c only when poll backend is enabled (disabled by default) 4548\& ev_poll.c only when poll backend is enabled
4528\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 4549\& ev_epoll.c only when the epoll backend is enabled
4529\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 4550\& ev_kqueue.c only when the kqueue backend is enabled
4530\& ev_port.c only when the solaris port backend is enabled (disabled by default) 4551\& ev_port.c only when the solaris port backend is enabled
4531.Ve 4552.Ve
4532.PP 4553.PP
4533\&\fIev.c\fR includes the backend files directly when enabled, so you only need 4554\&\fIev.c\fR includes the backend files directly when enabled, so you only need
4534to compile this single file. 4555to compile this single file.
4535.PP 4556.PP

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