ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev.3
(Generate patch)

Comparing libev/ev.3 (file contents):
Revision 1.1 by root, Tue Nov 13 03:11:57 2007 UTC vs.
Revision 1.7 by root, Fri Nov 23 08:36:35 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-13" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
… …
180.IX Header "GLOBAL FUNCTIONS" 180.IX Header "GLOBAL FUNCTIONS"
181These functions can be called anytime, even before initialising the 181These functions can be called anytime, even before initialising the
182library in any way. 182library in any way.
183.IP "ev_tstamp ev_time ()" 4 183.IP "ev_tstamp ev_time ()" 4
184.IX Item "ev_tstamp ev_time ()" 184.IX Item "ev_tstamp ev_time ()"
185Returns the current time as libev would use it. 185Returns the current time as libev would use it. Please note that the
186\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp
187you actually want to know.
186.IP "int ev_version_major ()" 4 188.IP "int ev_version_major ()" 4
187.IX Item "int ev_version_major ()" 189.IX Item "int ev_version_major ()"
188.PD 0 190.PD 0
189.IP "int ev_version_minor ()" 4 191.IP "int ev_version_minor ()" 4
190.IX Item "int ev_version_minor ()" 192.IX Item "int ev_version_minor ()"
… …
197.Sp 199.Sp
198Usually, it's a good idea to terminate if the major versions mismatch, 200Usually, it's a good idea to terminate if the major versions mismatch,
199as this indicates an incompatible change. Minor versions are usually 201as this indicates an incompatible change. Minor versions are usually
200compatible to older versions, so a larger minor version alone is usually 202compatible to older versions, so a larger minor version alone is usually
201not a problem. 203not a problem.
204.IP "unsigned int ev_supported_backends ()" 4
205.IX Item "unsigned int ev_supported_backends ()"
206Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR
207value) compiled into this binary of libev (independent of their
208availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for
209a description of the set values.
210.IP "unsigned int ev_recommended_backends ()" 4
211.IX Item "unsigned int ev_recommended_backends ()"
212Return the set of all backends compiled into this binary of libev and also
213recommended for this platform. This set is often smaller than the one
214returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on
215most BSDs and will not be autodetected unless you explicitly request it
216(assuming you know what you are doing). This is the set of backends that
217\&\f(CW\*(C`EVFLAG_AUTO\*(C'\fR will probe for.
202.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 218.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
203.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 219.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
204Sets the allocation function to use (the prototype is similar to the 220Sets the allocation function to use (the prototype is similar to the
205realloc C function, the semantics are identical). It is used to allocate 221realloc C function, the semantics are identical). It is used to allocate
206and free memory (no surprises here). If it returns zero when memory 222and free memory (no surprises here). If it returns zero when memory
… …
234.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 250.IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4
235.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" 251.IX Item "struct ev_loop *ev_default_loop (unsigned int flags)"
236This will initialise the default event loop if it hasn't been initialised 252This will initialise the default event loop if it hasn't been initialised
237yet and return it. If the default loop could not be initialised, returns 253yet and return it. If the default loop could not be initialised, returns
238false. If it already was initialised it simply returns it (and ignores the 254false. If it already was initialised it simply returns it (and ignores the
239flags). 255flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards).
240.Sp 256.Sp
241If you don't know what event loop to use, use the one returned from this 257If you don't know what event loop to use, use the one returned from this
242function. 258function.
243.Sp 259.Sp
244The flags argument can be used to specify special behaviour or specific 260The flags argument can be used to specify special behaviour or specific
245backends to use, and is usually specified as 0 (or \s-1EVFLAG_AUTO\s0). 261backends to use, and is usually specified as \f(CW0\fR (or \s-1EVFLAG_AUTO\s0).
246.Sp 262.Sp
247It supports the following flags: 263It supports the following flags:
248.RS 4 264.RS 4
249.ie n .IP """EVFLAG_AUTO""" 4 265.ie n .IP """EVFLAG_AUTO""" 4
250.el .IP "\f(CWEVFLAG_AUTO\fR" 4 266.el .IP "\f(CWEVFLAG_AUTO\fR" 4
… …
258or setgid) then libev will \fInot\fR look at the environment variable 274or setgid) then libev will \fInot\fR look at the environment variable
259\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 275\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
260override the flags completely if it is found in the environment. This is 276override the flags completely if it is found in the environment. This is
261useful to try out specific backends to test their performance, or to work 277useful to try out specific backends to test their performance, or to work
262around bugs. 278around bugs.
263.ie n .IP """EVMETHOD_SELECT"" (portable select backend)" 4 279.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
264.el .IP "\f(CWEVMETHOD_SELECT\fR (portable select backend)" 4 280.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
265.IX Item "EVMETHOD_SELECT (portable select backend)" 281.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
266.PD 0 282This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
283libev tries to roll its own fd_set with no limits on the number of fds,
284but if that fails, expect a fairly low limit on the number of fds when
285using this backend. It doesn't scale too well (O(highest_fd)), but its usually
286the fastest backend for a low number of fds.
267.ie n .IP """EVMETHOD_POLL"" (poll backend, available everywhere except on windows)" 4 287.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
268.el .IP "\f(CWEVMETHOD_POLL\fR (poll backend, available everywhere except on windows)" 4 288.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
269.IX Item "EVMETHOD_POLL (poll backend, available everywhere except on windows)" 289.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
290And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than
291select, but handles sparse fds better and has no artificial limit on the
292number of fds you can use (except it will slow down considerably with a
293lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
270.ie n .IP """EVMETHOD_EPOLL"" (linux only)" 4 294.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
271.el .IP "\f(CWEVMETHOD_EPOLL\fR (linux only)" 4 295.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
272.IX Item "EVMETHOD_EPOLL (linux only)" 296.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
273.ie n .IP """EVMETHOD_KQUEUE"" (some bsds only)" 4 297For few fds, this backend is a bit little slower than poll and select,
274.el .IP "\f(CWEVMETHOD_KQUEUE\fR (some bsds only)" 4 298but it scales phenomenally better. While poll and select usually scale like
275.IX Item "EVMETHOD_KQUEUE (some bsds only)" 299O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
300either O(1) or O(active_fds).
301.Sp
302While stopping and starting an I/O watcher in the same iteration will
303result in some caching, there is still a syscall per such incident
304(because the fd could point to a different file description now), so its
305best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
306well if you register events for both fds.
307.Sp
308Please note that epoll sometimes generates spurious notifications, so you
309need to use non-blocking I/O or other means to avoid blocking when no data
310(or space) is available.
311.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
312.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
313.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
314Kqueue deserves special mention, as at the time of this writing, it
315was broken on all BSDs except NetBSD (usually it doesn't work with
316anything but sockets and pipes, except on Darwin, where of course its
317completely useless). For this reason its not being \*(L"autodetected\*(R" unless
318you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0).
319.Sp
320It scales in the same way as the epoll backend, but the interface to the
321kernel is more efficient (which says nothing about its actual speed, of
322course). While starting and stopping an I/O watcher does not cause an
323extra syscall as with epoll, it still adds up to four event changes per
324incident, so its best to avoid that.
276.ie n .IP """EVMETHOD_DEVPOLL"" (solaris 8 only)" 4 325.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
277.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (solaris 8 only)" 4 326.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
278.IX Item "EVMETHOD_DEVPOLL (solaris 8 only)" 327.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
328This is not implemented yet (and might never be).
279.ie n .IP """EVMETHOD_PORT"" (solaris 10 only)" 4 329.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
280.el .IP "\f(CWEVMETHOD_PORT\fR (solaris 10 only)" 4 330.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
281.IX Item "EVMETHOD_PORT (solaris 10 only)" 331.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
282.PD 332This uses the Solaris 10 port mechanism. As with everything on Solaris,
283If one or more of these are ored into the flags value, then only these 333it's really slow, but it still scales very well (O(active_fds)).
284backends will be tried (in the reverse order as given here). If one are 334.Sp
285specified, any backend will do. 335Please note that solaris ports can result in a lot of spurious
336notifications, so you need to use non-blocking I/O or other means to avoid
337blocking when no data (or space) is available.
338.ie n .IP """EVBACKEND_ALL""" 4
339.el .IP "\f(CWEVBACKEND_ALL\fR" 4
340.IX Item "EVBACKEND_ALL"
341Try all backends (even potentially broken ones that wouldn't be tried
342with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as
343\&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR.
286.RE 344.RE
287.RS 4 345.RS 4
346.Sp
347If one or more of these are ored into the flags value, then only these
348backends will be tried (in the reverse order as given here). If none are
349specified, most compiled-in backend will be tried, usually in reverse
350order of their flag values :)
288.RE 351.RE
289.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 352.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
290.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 353.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
291Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 354Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
292always distinct from the default loop. Unlike the default loop, it cannot 355always distinct from the default loop. Unlike the default loop, it cannot
… …
306This function reinitialises the kernel state for backends that have 369This function reinitialises the kernel state for backends that have
307one. Despite the name, you can call it anytime, but it makes most sense 370one. Despite the name, you can call it anytime, but it makes most sense
308after forking, in either the parent or child process (or both, but that 371after forking, in either the parent or child process (or both, but that
309again makes little sense). 372again makes little sense).
310.Sp 373.Sp
311You \fImust\fR call this function after forking if and only if you want to 374You \fImust\fR call this function in the child process after forking if and
312use the event library in both processes. If you just fork+exec, you don't 375only if you want to use the event library in both processes. If you just
313have to call it. 376fork+exec, you don't have to call it.
314.Sp 377.Sp
315The function itself is quite fast and it's usually not a problem to call 378The function itself is quite fast and it's usually not a problem to call
316it just in case after a fork. To make this easy, the function will fit in 379it just in case after a fork. To make this easy, the function will fit in
317quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: 380quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR:
318.Sp 381.Sp
319.Vb 1 382.Vb 1
320\& pthread_atfork (0, 0, ev_default_fork); 383\& pthread_atfork (0, 0, ev_default_fork);
321.Ve 384.Ve
385.Sp
386At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use
387without calling this function, so if you force one of those backends you
388do not need to care.
322.IP "ev_loop_fork (loop)" 4 389.IP "ev_loop_fork (loop)" 4
323.IX Item "ev_loop_fork (loop)" 390.IX Item "ev_loop_fork (loop)"
324Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 391Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
325\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 392\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
326after fork, and how you do this is entirely your own problem. 393after fork, and how you do this is entirely your own problem.
327.IP "unsigned int ev_method (loop)" 4 394.IP "unsigned int ev_backend (loop)" 4
328.IX Item "unsigned int ev_method (loop)" 395.IX Item "unsigned int ev_backend (loop)"
329Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in 396Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
330use. 397use.
331.IP "ev_tstamp ev_now (loop)" 4 398.IP "ev_tstamp ev_now (loop)" 4
332.IX Item "ev_tstamp ev_now (loop)" 399.IX Item "ev_tstamp ev_now (loop)"
333Returns the current \*(L"event loop time\*(R", which is the time the event loop 400Returns the current \*(L"event loop time\*(R", which is the time the event loop
334got events and started processing them. This timestamp does not change 401got events and started processing them. This timestamp does not change
… …
354one iteration of the loop. 421one iteration of the loop.
355.Sp 422.Sp
356This flags value could be used to implement alternative looping 423This flags value could be used to implement alternative looping
357constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and 424constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and
358more generic mechanism. 425more generic mechanism.
426.Sp
427Here are the gory details of what ev_loop does:
428.Sp
429.Vb 15
430\& 1. If there are no active watchers (reference count is zero), return.
431\& 2. Queue and immediately call all prepare watchers.
432\& 3. If we have been forked, recreate the kernel state.
433\& 4. Update the kernel state with all outstanding changes.
434\& 5. Update the "event loop time".
435\& 6. Calculate for how long to block.
436\& 7. Block the process, waiting for events.
437\& 8. Update the "event loop time" and do time jump handling.
438\& 9. Queue all outstanding timers.
439\& 10. Queue all outstanding periodics.
440\& 11. If no events are pending now, queue all idle watchers.
441\& 12. Queue all check watchers.
442\& 13. Call all queued watchers in reverse order (i.e. check watchers first).
443\& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
444\& was used, return, otherwise continue with step #1.
445.Ve
359.IP "ev_unloop (loop, how)" 4 446.IP "ev_unloop (loop, how)" 4
360.IX Item "ev_unloop (loop, how)" 447.IX Item "ev_unloop (loop, how)"
361Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it 448Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it
362has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either 449has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either
363\&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or 450\&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or
… …
421*)\*(C'\fR), and you can stop watching for events at any time by calling the 508*)\*(C'\fR), and you can stop watching for events at any time by calling the
422corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. 509corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR.
423.PP 510.PP
424As long as your watcher is active (has been started but not stopped) you 511As long as your watcher is active (has been started but not stopped) you
425must not touch the values stored in it. Most specifically you must never 512must not touch the values stored in it. Most specifically you must never
426reinitialise it or call its set method. 513reinitialise it or call its set macro.
427.PP 514.PP
428You can check whether an event is active by calling the \f(CW\*(C`ev_is_active 515You can check whether an event is active by calling the \f(CW\*(C`ev_is_active
429(watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the 516(watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the
430callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending 517callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
431(watcher *)\*(C'\fR macro. 518(watcher *)\*(C'\fR macro.
… …
551descriptors correctly if you register interest in two or more fds pointing 638descriptors correctly if you register interest in two or more fds pointing
552to the same underlying file/socket etc. description (that is, they share 639to the same underlying file/socket etc. description (that is, they share
553the same underlying \*(L"file open\*(R"). 640the same underlying \*(L"file open\*(R").
554.PP 641.PP
555If you must do this, then force the use of a known-to-be-good backend 642If you must do this, then force the use of a known-to-be-good backend
556(at the time of this writing, this includes only \s-1EVMETHOD_SELECT\s0 and 643(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
557\&\s-1EVMETHOD_POLL\s0). 644\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
558.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 645.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
559.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 646.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
560.PD 0 647.PD 0
561.IP "ev_io_set (ev_io *, int fd, int events)" 4 648.IP "ev_io_set (ev_io *, int fd, int events)" 4
562.IX Item "ev_io_set (ev_io *, int fd, int events)" 649.IX Item "ev_io_set (ev_io *, int fd, int events)"
563.PD 650.PD
564Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 651Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive
565events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | 652events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ |
566EV_WRITE\*(C'\fR to receive the given events. 653EV_WRITE\*(C'\fR to receive the given events.
654.Sp
655Please note that most of the more scalable backend mechanisms (for example
656epoll and solaris ports) can result in spurious readyness notifications
657for file descriptors, so you practically need to use non-blocking I/O (and
658treat callback invocation as hint only), or retest separately with a safe
659interface before doing I/O (XLib can do this), or force the use of either
660\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
661problem. Also note that it is quite easy to have your callback invoked
662when the readyness condition is no longer valid even when employing
663typical ways of handling events, so its a good idea to use non-blocking
664I/O unconditionally.
567.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 665.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"
568.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 666.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"
569.IX Subsection "ev_timer - relative and optionally recurring timeouts" 667.IX Subsection "ev_timer - relative and optionally recurring timeouts"
570Timer watchers are simple relative timers that generate an event after a 668Timer watchers are simple relative timers that generate an event after a
571given time, and optionally repeating in regular intervals after that. 669given time, and optionally repeating in regular intervals after that.
572.PP 670.PP
573The timers are based on real time, that is, if you register an event that 671The timers are based on real time, that is, if you register an event that
574times out after an hour and you reset your system clock to last years 672times out after an hour and you reset your system clock to last years
575time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because 673time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because
576detecting time jumps is hard, and soem inaccuracies are unavoidable (the 674detecting time jumps is hard, and some inaccuracies are unavoidable (the
577monotonic clock option helps a lot here). 675monotonic clock option helps a lot here).
578.PP 676.PP
579The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR 677The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR
580time. This is usually the right thing as this timestamp refers to the time 678time. This is usually the right thing as this timestamp refers to the time
581of the event triggering whatever timeout you are modifying/starting. If 679of the event triggering whatever timeout you are modifying/starting. If
582you suspect event processing to be delayed and you *need* to base the timeout 680you suspect event processing to be delayed and you \fIneed\fR to base the timeout
583on the current time, use something like this to adjust for this: 681on the current time, use something like this to adjust for this:
584.PP 682.PP
585.Vb 1 683.Vb 1
586\& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); 684\& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
587.Ve 685.Ve
686.PP
687The callback is guarenteed to be invoked only when its timeout has passed,
688but if multiple timers become ready during the same loop iteration then
689order of execution is undefined.
588.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 690.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
589.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 691.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
590.PD 0 692.PD 0
591.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 693.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
592.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 694.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
… …
634roughly 10 seconds later and of course not if you reset your system time 736roughly 10 seconds later and of course not if you reset your system time
635again). 737again).
636.PP 738.PP
637They can also be used to implement vastly more complex timers, such as 739They can also be used to implement vastly more complex timers, such as
638triggering an event on eahc midnight, local time. 740triggering an event on eahc midnight, local time.
741.PP
742As with timers, the callback is guarenteed to be invoked only when the
743time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
744during the same loop iteration then order of execution is undefined.
639.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 745.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
640.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 746.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
641.PD 0 747.PD 0
642.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 748.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
643.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 749.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines