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Revision 1.30 by root, Wed Nov 28 11:27:29 2007 UTC vs.
Revision 1.57 by root, Sat Dec 22 11:49:17 2007 UTC

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126. ds Ae AE 126. ds Ae AE
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 "EV 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH EV 1 "2007-12-22" "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
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196\& return 0; 196\& return 0;
197\& } 197\& }
198.Ve 198.Ve
199.SH "DESCRIPTION" 199.SH "DESCRIPTION"
200.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
201The newest version of this document is also available as a html-formatted
202web page you might find easier to navigate when reading it for the first
203time: <http://cvs.schmorp.de/libev/ev.html>.
204.PP
201Libev is an event loop: you register interest in certain events (such as a 205Libev is an event loop: you register interest in certain events (such as a
202file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occurring), and it will manage
203these event sources and provide your program with events. 207these event sources and provide your program with events.
204.PP 208.PP
205To do this, it must take more or less complete control over your process 209To do this, it must take more or less complete control over your process
206(or thread) by executing the \fIevent loop\fR handler, and will then 210(or thread) by executing the \fIevent loop\fR handler, and will then
207communicate events via a callback mechanism. 211communicate events via a callback mechanism.
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210watchers\fR, which are relatively small C structures you initialise with the 214watchers\fR, which are relatively small C structures you initialise with the
211details of the event, and then hand it over to libev by \fIstarting\fR the 215details of the event, and then hand it over to libev by \fIstarting\fR the
212watcher. 216watcher.
213.SH "FEATURES" 217.SH "FEATURES"
214.IX Header "FEATURES" 218.IX Header "FEATURES"
215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the linux-specific \f(CW\*(C`epoll\*(C'\fR, the 219Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms 220BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), 221for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
222(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous 223with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and 224(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 225watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
221\&\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 226\&\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
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 227file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR). 228(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP 229.PP
225It also is quite fast (see this 230It also is quite fast (see this
… …
238Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
239(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 244(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
240the beginning of 1970, details are complicated, don't ask). This type is 245the beginning of 1970, details are complicated, don't ask). This type is
241called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases 246called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
242to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on 247to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
243it, you should treat it as such. 248it, you should treat it as some floatingpoint value. Unlike the name
249component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences
250throughout libev.
244.SH "GLOBAL FUNCTIONS" 251.SH "GLOBAL FUNCTIONS"
245.IX Header "GLOBAL FUNCTIONS" 252.IX Header "GLOBAL FUNCTIONS"
246These functions can be called anytime, even before initialising the 253These functions can be called anytime, even before initialising the
247library in any way. 254library in any way.
248.IP "ev_tstamp ev_time ()" 4 255.IP "ev_tstamp ev_time ()" 4
249.IX Item "ev_tstamp ev_time ()" 256.IX Item "ev_tstamp ev_time ()"
250Returns the current time as libev would use it. Please note that the 257Returns the current time as libev would use it. Please note that the
251\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp 258\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp
252you actually want to know. 259you actually want to know.
260.IP "ev_sleep (ev_tstamp interval)" 4
261.IX Item "ev_sleep (ev_tstamp interval)"
262Sleep for the given interval: The current thread will be blocked until
263either it is interrupted or the given time interval has passed. Basically
264this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR.
253.IP "int ev_version_major ()" 4 265.IP "int ev_version_major ()" 4
254.IX Item "int ev_version_major ()" 266.IX Item "int ev_version_major ()"
255.PD 0 267.PD 0
256.IP "int ev_version_minor ()" 4 268.IP "int ev_version_minor ()" 4
257.IX Item "int ev_version_minor ()" 269.IX Item "int ev_version_minor ()"
258.PD 270.PD
259You can find out the major and minor version numbers of the library 271You can find out the major and minor \s-1ABI\s0 version numbers of the library
260you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 272you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
261\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 273\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
262symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 274symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
263version of the library your program was compiled against. 275version of the library your program was compiled against.
264.Sp 276.Sp
277These version numbers refer to the \s-1ABI\s0 version of the library, not the
278release version.
279.Sp
265Usually, it's a good idea to terminate if the major versions mismatch, 280Usually, it's a good idea to terminate if the major versions mismatch,
266as this indicates an incompatible change. Minor versions are usually 281as this indicates an incompatible change. Minor versions are usually
267compatible to older versions, so a larger minor version alone is usually 282compatible to older versions, so a larger minor version alone is usually
268not a problem. 283not a problem.
269.Sp 284.Sp
270Example: Make sure we haven't accidentally been linked against the wrong 285Example: Make sure we haven't accidentally been linked against the wrong
271version. 286version.
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304might be supported on the current system, you would need to look at 319might be supported on the current system, you would need to look at
305\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for 320\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones. 321recommended ones.
307.Sp 322.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 323See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
309.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 324.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 325.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
311Sets the allocation function to use (the prototype and semantics are 326Sets the allocation function to use (the prototype is similar \- the
312identical to the realloc C function). It is used to allocate and free 327semantics is identical \- to the realloc C function). It is used to
313memory (no surprises here). If it returns zero when memory needs to be 328allocate and free memory (no surprises here). If it returns zero when
314allocated, the library might abort or take some potentially destructive 329memory needs to be allocated, the library might abort or take some
315action. The default is your system realloc function. 330potentially destructive action. The default is your system realloc
331function.
316.Sp 332.Sp
317You could override this function in high-availability programs to, say, 333You could override this function in high-availability programs to, say,
318free some memory if it cannot allocate memory, to use a special allocator, 334free some memory if it cannot allocate memory, to use a special allocator,
319or even to sleep a while and retry until some memory is available. 335or even to sleep a while and retry until some memory is available.
320.Sp 336.Sp
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409or setgid) then libev will \fInot\fR look at the environment variable 425or setgid) then libev will \fInot\fR look at the environment variable
410\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 426\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
411override the flags completely if it is found in the environment. This is 427override the flags completely if it is found in the environment. This is
412useful to try out specific backends to test their performance, or to work 428useful to try out specific backends to test their performance, or to work
413around bugs. 429around bugs.
430.ie n .IP """EVFLAG_FORKCHECK""" 4
431.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
432.IX Item "EVFLAG_FORKCHECK"
433Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
434a fork, you can also make libev check for a fork in each iteration by
435enabling this flag.
436.Sp
437This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
438and thus this might slow down your event loop if you do a lot of loop
439iterations and little real work, but is usually not noticeable (on my
440Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
441without a syscall and thus \fIvery\fR fast, but my Linux system also has
442\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
443.Sp
444The big advantage of this flag is that you can forget about fork (and
445forget about forgetting to tell libev about forking) when you use this
446flag.
447.Sp
448This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
449environment variable.
414.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 450.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
415.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 451.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
416.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 452.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
417This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 453This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
418libev tries to roll its own fd_set with no limits on the number of fds, 454libev tries to roll its own fd_set with no limits on the number of fds,
… …
428lot of inactive fds). It scales similarly to select, i.e. O(total_fds). 464lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
429.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 465.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
430.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 466.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
431.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 467.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
432For few fds, this backend is a bit little slower than poll and select, 468For few fds, this backend is a bit little slower than poll and select,
433but it scales phenomenally better. While poll and select usually scale like 469but it scales phenomenally better. While poll and select usually scale
434O(total_fds) where n is the total number of fds (or the highest fd), epoll scales 470like O(total_fds) where n is the total number of fds (or the highest fd),
435either O(1) or O(active_fds). 471epoll scales either O(1) or O(active_fds). The epoll design has a number
472of shortcomings, such as silently dropping events in some hard-to-detect
473cases and rewiring a syscall per fd change, no fork support and bad
474support for dup:
436.Sp 475.Sp
437While stopping and starting an I/O watcher in the same iteration will 476While stopping, setting and starting an I/O watcher in the same iteration
438result in some caching, there is still a syscall per such incident 477will result in some caching, there is still a syscall per such incident
439(because the fd could point to a different file description now), so its 478(because the fd could point to a different file description now), so its
440best to avoid that. Also, \fIdup()\fRed file descriptors might not work very 479best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work
441well if you register events for both fds. 480very well if you register events for both fds.
442.Sp 481.Sp
443Please note that epoll sometimes generates spurious notifications, so you 482Please note that epoll sometimes generates spurious notifications, so you
444need to use non-blocking I/O or other means to avoid blocking when no data 483need to use non-blocking I/O or other means to avoid blocking when no data
445(or space) is available. 484(or space) is available.
446.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 485.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
447.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 486.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
448.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 487.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
449Kqueue deserves special mention, as at the time of this writing, it 488Kqueue deserves special mention, as at the time of this writing, it
450was broken on all BSDs except NetBSD (usually it doesn't work with 489was broken on all BSDs except NetBSD (usually it doesn't work reliably
451anything but sockets and pipes, except on Darwin, where of course its 490with anything but sockets and pipes, except on Darwin, where of course
452completely useless). For this reason its not being \*(L"autodetected\*(R" 491it's completely useless). For this reason it's not being \*(L"autodetected\*(R"
453unless you explicitly specify it explicitly in the flags (i.e. using 492unless you explicitly specify it explicitly in the flags (i.e. using
454\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). 493\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough)
494system like NetBSD.
495.Sp
496You still can embed kqueue into a normal poll or select backend and use it
497only for sockets (after having made sure that sockets work with kqueue on
498the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
455.Sp 499.Sp
456It scales in the same way as the epoll backend, but the interface to the 500It scales in the same way as the epoll backend, but the interface to the
457kernel is more efficient (which says nothing about its actual speed, of 501kernel is more efficient (which says nothing about its actual speed, of
458course). While starting and stopping an I/O watcher does not cause an 502course). While stopping, setting and starting an I/O watcher does never
459extra syscall as with epoll, it still adds up to four event changes per 503cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
460incident, so its best to avoid that. 504two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it
505drops fds silently in similarly hard-to-detect cases.
461.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 506.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
462.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 507.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
463.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" 508.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
464This is not implemented yet (and might never be). 509This is not implemented yet (and might never be).
465.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 510.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
466.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 511.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
467.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 512.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
468This uses the Solaris 10 port mechanism. As with everything on Solaris, 513This uses the Solaris 10 event port mechanism. As with everything on Solaris,
469it's really slow, but it still scales very well (O(active_fds)). 514it's really slow, but it still scales very well (O(active_fds)).
470.Sp 515.Sp
471Please note that solaris ports can result in a lot of spurious 516Please note that solaris event ports can deliver a lot of spurious
472notifications, so you need to use non-blocking I/O or other means to avoid 517notifications, so you need to use non-blocking I/O or other means to avoid
473blocking when no data (or space) is available. 518blocking when no data (or space) is available.
474.ie n .IP """EVBACKEND_ALL""" 4 519.ie n .IP """EVBACKEND_ALL""" 4
475.el .IP "\f(CWEVBACKEND_ALL\fR" 4 520.el .IP "\f(CWEVBACKEND_ALL\fR" 4
476.IX Item "EVBACKEND_ALL" 521.IX Item "EVBACKEND_ALL"
… …
526Destroys the default loop again (frees all memory and kernel state 571Destroys the default loop again (frees all memory and kernel state
527etc.). None of the active event watchers will be stopped in the normal 572etc.). None of the active event watchers will be stopped in the normal
528sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your 573sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
529responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 574responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
530calling this function, or cope with the fact afterwards (which is usually 575calling this function, or cope with the fact afterwards (which is usually
531the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them 576the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
532for example). 577for example).
578.Sp
579Note that certain global state, such as signal state, will not be freed by
580this function, and related watchers (such as signal and child watchers)
581would need to be stopped manually.
582.Sp
583In general it is not advisable to call this function except in the
584rare occasion where you really need to free e.g. the signal handling
585pipe fds. If you need dynamically allocated loops it is better to use
586\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR).
533.IP "ev_loop_destroy (loop)" 4 587.IP "ev_loop_destroy (loop)" 4
534.IX Item "ev_loop_destroy (loop)" 588.IX Item "ev_loop_destroy (loop)"
535Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 589Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
536earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 590earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
537.IP "ev_default_fork ()" 4 591.IP "ev_default_fork ()" 4
… …
559.IP "ev_loop_fork (loop)" 4 613.IP "ev_loop_fork (loop)" 4
560.IX Item "ev_loop_fork (loop)" 614.IX Item "ev_loop_fork (loop)"
561Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 615Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
562\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 616\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
563after fork, and how you do this is entirely your own problem. 617after fork, and how you do this is entirely your own problem.
618.IP "unsigned int ev_loop_count (loop)" 4
619.IX Item "unsigned int ev_loop_count (loop)"
620Returns the count of loop iterations for the loop, which is identical to
621the number of times libev did poll for new events. It starts at \f(CW0\fR and
622happily wraps around with enough iterations.
623.Sp
624This value can sometimes be useful as a generation counter of sorts (it
625\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
626\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
564.IP "unsigned int ev_backend (loop)" 4 627.IP "unsigned int ev_backend (loop)" 4
565.IX Item "unsigned int ev_backend (loop)" 628.IX Item "unsigned int ev_backend (loop)"
566Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 629Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
567use. 630use.
568.IP "ev_tstamp ev_now (loop)" 4 631.IP "ev_tstamp ev_now (loop)" 4
569.IX Item "ev_tstamp ev_now (loop)" 632.IX Item "ev_tstamp ev_now (loop)"
570Returns the current \*(L"event loop time\*(R", which is the time the event loop 633Returns the current \*(L"event loop time\*(R", which is the time the event loop
571received events and started processing them. This timestamp does not 634received events and started processing them. This timestamp does not
572change as long as callbacks are being processed, and this is also the base 635change as long as callbacks are being processed, and this is also the base
573time used for relative timers. You can treat it as the timestamp of the 636time used for relative timers. You can treat it as the timestamp of the
574event occuring (or more correctly, libev finding out about it). 637event occurring (or more correctly, libev finding out about it).
575.IP "ev_loop (loop, int flags)" 4 638.IP "ev_loop (loop, int flags)" 4
576.IX Item "ev_loop (loop, int flags)" 639.IX Item "ev_loop (loop, int flags)"
577Finally, this is it, the event handler. This function usually is called 640Finally, this is it, the event handler. This function usually is called
578after you initialised all your watchers and you want to start handling 641after you initialised all your watchers and you want to start handling
579events. 642events.
… …
599libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 662libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
600usually a better approach for this kind of thing. 663usually a better approach for this kind of thing.
601.Sp 664.Sp
602Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 665Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
603.Sp 666.Sp
604.Vb 18 667.Vb 19
668\& - Before the first iteration, call any pending watchers.
605\& * If there are no active watchers (reference count is zero), return. 669\& * If there are no active watchers (reference count is zero), return.
606\& - Queue prepare watchers and then call all outstanding watchers. 670\& - Queue all prepare watchers and then call all outstanding watchers.
607\& - If we have been forked, recreate the kernel state. 671\& - If we have been forked, recreate the kernel state.
608\& - Update the kernel state with all outstanding changes. 672\& - Update the kernel state with all outstanding changes.
609\& - Update the "event loop time". 673\& - Update the "event loop time".
610\& - Calculate for how long to block. 674\& - Calculate for how long to block.
611\& - Block the process, waiting for any events. 675\& - Block the process, waiting for any events.
… …
668.Sp 732.Sp
669.Vb 2 733.Vb 2
670\& ev_ref (loop); 734\& ev_ref (loop);
671\& ev_signal_stop (loop, &exitsig); 735\& ev_signal_stop (loop, &exitsig);
672.Ve 736.Ve
737.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4
738.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)"
739.PD 0
740.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4
741.IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)"
742.PD
743These advanced functions influence the time that libev will spend waiting
744for events. Both are by default \f(CW0\fR, meaning that libev will try to
745invoke timer/periodic callbacks and I/O callbacks with minimum latency.
746.Sp
747Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR)
748allows libev to delay invocation of I/O and timer/periodic callbacks to
749increase efficiency of loop iterations.
750.Sp
751The background is that sometimes your program runs just fast enough to
752handle one (or very few) event(s) per loop iteration. While this makes
753the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new
754events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high
755overhead for the actual polling but can deliver many events at once.
756.Sp
757By setting a higher \fIio collect interval\fR you allow libev to spend more
758time collecting I/O events, so you can handle more events per iteration,
759at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and
760\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null bvalue will
761introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations.
762.Sp
763Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
764to spend more time collecting timeouts, at the expense of increased
765latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers
766will not be affected. Setting this to a non-null value will not introduce
767any overhead in libev.
768.Sp
769Many (busy) programs can usually benefit by setting the io collect
770interval to a value near \f(CW0.1\fR or so, which is often enough for
771interactive servers (of course not for games), likewise for timeouts. It
772usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
773as this approsaches the timing granularity of most systems.
673.SH "ANATOMY OF A WATCHER" 774.SH "ANATOMY OF A WATCHER"
674.IX Header "ANATOMY OF A WATCHER" 775.IX Header "ANATOMY OF A WATCHER"
675A watcher is a structure that you create and register to record your 776A watcher is a structure that you create and register to record your
676interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 777interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
677become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: 778become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
… …
854.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 955.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
855.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 956.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
856Returns a true value iff the watcher is pending, (i.e. it has outstanding 957Returns a true value iff the watcher is pending, (i.e. it has outstanding
857events but its callback has not yet been invoked). As long as a watcher 958events but its callback has not yet been invoked). As long as a watcher
858is pending (but not active) you must not call an init function on it (but 959is pending (but not active) you must not call an init function on it (but
859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 960\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 961make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
962it).
861.IP "callback ev_cb (ev_TYPE *watcher)" 4 963.IP "callback ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback ev_cb (ev_TYPE *watcher)" 964.IX Item "callback ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher. 965Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 966.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 967.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time 968Change the callback. You can change the callback at virtually any time
867(modulo threads). 969(modulo threads).
970.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
971.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
972.PD 0
973.IP "int ev_priority (ev_TYPE *watcher)" 4
974.IX Item "int ev_priority (ev_TYPE *watcher)"
975.PD
976Set and query the priority of the watcher. The priority is a small
977integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
978(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
979before watchers with lower priority, but priority will not keep watchers
980from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
981.Sp
982This means that priorities are \fIonly\fR used for ordering callback
983invocation after new events have been received. This is useful, for
984example, to reduce latency after idling, or more often, to bind two
985watchers on the same event and make sure one is called first.
986.Sp
987If you need to suppress invocation when higher priority events are pending
988you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
989.Sp
990You \fImust not\fR change the priority of a watcher as long as it is active or
991pending.
992.Sp
993The default priority used by watchers when no priority has been set is
994always \f(CW0\fR, which is supposed to not be too high and not be too low :).
995.Sp
996Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
997fine, as long as you do not mind that the priority value you query might
998or might not have been adjusted to be within valid range.
999.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
1000.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
1001Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
1002\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
1003can deal with that fact.
1004.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
1005.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
1006If the watcher is pending, this function returns clears its pending status
1007and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
1008watcher isn't pending it does nothing and returns \f(CW0\fR.
868.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 1009.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
869.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 1010.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
870Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 1011Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
871and read at any time, libev will completely ignore it. This can be used 1012and read at any time, libev will completely ignore it. This can be used
872to associate arbitrary data with your watcher. If you need more data and 1013to associate arbitrary data with your watcher. If you need more data and
… …
983it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1124it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
984\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1125\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
985.PP 1126.PP
986If you cannot run the fd in non-blocking mode (for example you should not 1127If you cannot run the fd in non-blocking mode (for example you should not
987play around with an Xlib connection), then you have to seperately re-test 1128play around with an Xlib connection), then you have to seperately re-test
988wether a file descriptor is really ready with a known-to-be good interface 1129whether a file descriptor is really ready with a known-to-be good interface
989such as poll (fortunately in our Xlib example, Xlib already does this on 1130such as poll (fortunately in our Xlib example, Xlib already does this on
990its own, so its quite safe to use). 1131its own, so its quite safe to use).
1132.PP
1133\fIThe special problem of disappearing file descriptors\fR
1134.IX Subsection "The special problem of disappearing file descriptors"
1135.PP
1136Some backends (e.g. kqueue, epoll) need to be told about closing a file
1137descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1138such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1139descriptor, but when it goes away, the operating system will silently drop
1140this interest. If another file descriptor with the same number then is
1141registered with libev, there is no efficient way to see that this is, in
1142fact, a different file descriptor.
1143.PP
1144To avoid having to explicitly tell libev about such cases, libev follows
1145the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1146will assume that this is potentially a new file descriptor, otherwise
1147it is assumed that the file descriptor stays the same. That means that
1148you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
1149descriptor even if the file descriptor number itself did not change.
1150.PP
1151This is how one would do it normally anyway, the important point is that
1152the libev application should not optimise around libev but should leave
1153optimisations to libev.
1154.PP
1155\fIThe special problem of dup'ed file descriptors\fR
1156.IX Subsection "The special problem of dup'ed file descriptors"
1157.PP
1158Some backends (e.g. epoll), cannot register events for file descriptors,
1159but only events for the underlying file descriptions. That menas when you
1160have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one
1161file descriptor might actually receive events.
1162.PP
1163There is no workaorund possible except not registering events
1164for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to
1165\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1166.PP
1167\fIThe special problem of fork\fR
1168.IX Subsection "The special problem of fork"
1169.PP
1170Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit
1171useless behaviour. Libev fully supports fork, but needs to be told about
1172it in the child.
1173.PP
1174To support fork in your programs, you either have to call
1175\&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child,
1176enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or
1177\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1178.PP
1179\fIWatcher-Specific Functions\fR
1180.IX Subsection "Watcher-Specific Functions"
991.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1181.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
992.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1182.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
993.PD 0 1183.PD 0
994.IP "ev_io_set (ev_io *, int fd, int events)" 4 1184.IP "ev_io_set (ev_io *, int fd, int events)" 4
995.IX Item "ev_io_set (ev_io *, int fd, int events)" 1185.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1048.Ve 1238.Ve
1049.PP 1239.PP
1050The callback is guarenteed to be invoked only when its timeout has passed, 1240The callback is guarenteed to be invoked only when its timeout has passed,
1051but if multiple timers become ready during the same loop iteration then 1241but if multiple timers become ready during the same loop iteration then
1052order of execution is undefined. 1242order of execution is undefined.
1243.PP
1244\fIWatcher-Specific Functions and Data Members\fR
1245.IX Subsection "Watcher-Specific Functions and Data Members"
1053.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1246.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1054.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1247.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
1055.PD 0 1248.PD 0
1056.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 1249.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
1057.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 1250.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
… …
1069.IP "ev_timer_again (loop)" 4 1262.IP "ev_timer_again (loop)" 4
1070.IX Item "ev_timer_again (loop)" 1263.IX Item "ev_timer_again (loop)"
1071This will act as if the timer timed out and restart it again if it is 1264This will act as if the timer timed out and restart it again if it is
1072repeating. The exact semantics are: 1265repeating. The exact semantics are:
1073.Sp 1266.Sp
1267If the timer is pending, its pending status is cleared.
1268.Sp
1074If the timer is started but nonrepeating, stop it. 1269If the timer is started but nonrepeating, stop it (as if it timed out).
1075.Sp 1270.Sp
1076If the timer is repeating, either start it if necessary (with the repeat 1271If the timer is repeating, either start it if necessary (with the
1077value), or reset the running timer to the repeat value. 1272\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1078.Sp 1273.Sp
1079This sounds a bit complicated, but here is a useful and typical 1274This sounds a bit complicated, but here is a useful and typical
1080example: Imagine you have a tcp connection and you want a so-called 1275example: Imagine you have a tcp connection and you want a so-called idle
1081idle timeout, that is, you want to be called when there have been, 1276timeout, that is, you want to be called when there have been, say, 60
1082say, 60 seconds of inactivity on the socket. The easiest way to do 1277seconds of inactivity on the socket. The easiest way to do this is to
1083this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling 1278configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1084\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1279\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1085you go into an idle state where you do not expect data to travel on the 1280you go into an idle state where you do not expect data to travel on the
1086socket, you can stop the timer, and again will automatically restart it if 1281socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1087need be. 1282automatically restart it if need be.
1088.Sp 1283.Sp
1089You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1284That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1090and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1285altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1091.Sp 1286.Sp
1092.Vb 8 1287.Vb 8
1093\& ev_timer_init (timer, callback, 0., 5.); 1288\& ev_timer_init (timer, callback, 0., 5.);
1094\& ev_timer_again (loop, timer); 1289\& ev_timer_again (loop, timer);
1095\& ... 1290\& ...
… …
1098\& ... 1293\& ...
1099\& timer->again = 10.; 1294\& timer->again = 10.;
1100\& ev_timer_again (loop, timer); 1295\& ev_timer_again (loop, timer);
1101.Ve 1296.Ve
1102.Sp 1297.Sp
1103This is more efficient then stopping/starting the timer eahc time you want 1298This is more slightly efficient then stopping/starting the timer each time
1104to modify its timeout value. 1299you want to modify its timeout value.
1105.IP "ev_tstamp repeat [read\-write]" 4 1300.IP "ev_tstamp repeat [read\-write]" 4
1106.IX Item "ev_tstamp repeat [read-write]" 1301.IX Item "ev_tstamp repeat [read-write]"
1107The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1302The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1108or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1303or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1109which is also when any modifications are taken into account. 1304which is also when any modifications are taken into account.
… …
1157but on wallclock time (absolute time). You can tell a periodic watcher 1352but on wallclock time (absolute time). You can tell a periodic watcher
1158to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1353to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1159periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1354periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1160+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1355+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1161take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1356take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1162roughly 10 seconds later and of course not if you reset your system time 1357roughly 10 seconds later).
1163again).
1164.PP 1358.PP
1165They can also be used to implement vastly more complex timers, such as 1359They can also be used to implement vastly more complex timers, such as
1166triggering an event on eahc midnight, local time. 1360triggering an event on each midnight, local time or other, complicated,
1361rules.
1167.PP 1362.PP
1168As with timers, the callback is guarenteed to be invoked only when the 1363As with timers, the callback is guarenteed to be invoked only when the
1169time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1364time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1170during the same loop iteration then order of execution is undefined. 1365during the same loop iteration then order of execution is undefined.
1366.PP
1367\fIWatcher-Specific Functions and Data Members\fR
1368.IX Subsection "Watcher-Specific Functions and Data Members"
1171.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1369.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1172.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 1370.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
1173.PD 0 1371.PD 0
1174.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 1372.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
1175.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1373.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1176.PD 1374.PD
1177Lots of arguments, lets sort it out... There are basically three modes of 1375Lots of arguments, lets sort it out... There are basically three modes of
1178operation, and we will explain them from simplest to complex: 1376operation, and we will explain them from simplest to complex:
1179.RS 4 1377.RS 4
1180.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1378.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1181.IX Item "absolute timer (interval = reschedule_cb = 0)" 1379.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1182In this configuration the watcher triggers an event at the wallclock time 1380In this configuration the watcher triggers an event at the wallclock time
1183\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1381\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1184that is, if it is to be run at January 1st 2011 then it will run when the 1382that is, if it is to be run at January 1st 2011 then it will run when the
1185system time reaches or surpasses this time. 1383system time reaches or surpasses this time.
1186.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1384.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1187.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1385.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1188In this mode the watcher will always be scheduled to time out at the next 1386In this mode the watcher will always be scheduled to time out at the next
1189\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1387\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1190of any time jumps. 1388and then repeat, regardless of any time jumps.
1191.Sp 1389.Sp
1192This can be used to create timers that do not drift with respect to system 1390This can be used to create timers that do not drift with respect to system
1193time: 1391time:
1194.Sp 1392.Sp
1195.Vb 1 1393.Vb 1
… …
1202by 3600. 1400by 3600.
1203.Sp 1401.Sp
1204Another way to think about it (for the mathematically inclined) is that 1402Another way to think about it (for the mathematically inclined) is that
1205\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1403\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1206time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1404time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1405.Sp
1406For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1407\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1408this value.
1207.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1409.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1208.IX Item "manual reschedule mode (reschedule_cb = callback)" 1410.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1209In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1411In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1210ignored. Instead, each time the periodic watcher gets scheduled, the 1412ignored. Instead, each time the periodic watcher gets scheduled, the
1211reschedule callback will be called with the watcher as first, and the 1413reschedule callback will be called with the watcher as first, and the
1212current time as second argument. 1414current time as second argument.
1213.Sp 1415.Sp
1214\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1416\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1215ever, or make any event loop modifications\fR. If you need to stop it, 1417ever, or make any event loop modifications\fR. If you need to stop it,
1216return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1418return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1217starting a prepare watcher). 1419starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1218.Sp 1420.Sp
1219Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1421Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1220ev_tstamp now)\*(C'\fR, e.g.: 1422ev_tstamp now)\*(C'\fR, e.g.:
1221.Sp 1423.Sp
1222.Vb 4 1424.Vb 4
… …
1246.IX Item "ev_periodic_again (loop, ev_periodic *)" 1448.IX Item "ev_periodic_again (loop, ev_periodic *)"
1247Simply stops and restarts the periodic watcher again. This is only useful 1449Simply stops and restarts the periodic watcher again. This is only useful
1248when you changed some parameters or the reschedule callback would return 1450when you changed some parameters or the reschedule callback would return
1249a different time than the last time it was called (e.g. in a crond like 1451a different time than the last time it was called (e.g. in a crond like
1250program when the crontabs have changed). 1452program when the crontabs have changed).
1453.IP "ev_tstamp offset [read\-write]" 4
1454.IX Item "ev_tstamp offset [read-write]"
1455When repeating, this contains the offset value, otherwise this is the
1456absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1457.Sp
1458Can be modified any time, but changes only take effect when the periodic
1459timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1251.IP "ev_tstamp interval [read\-write]" 4 1460.IP "ev_tstamp interval [read\-write]" 4
1252.IX Item "ev_tstamp interval [read-write]" 1461.IX Item "ev_tstamp interval [read-write]"
1253The current interval value. Can be modified any time, but changes only 1462The current interval value. Can be modified any time, but changes only
1254take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1463take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1255called. 1464called.
1256.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 1465.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1257.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1466.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1258The current reschedule callback, or \f(CW0\fR, if this functionality is 1467The current reschedule callback, or \f(CW0\fR, if this functionality is
1259switched off. Can be changed any time, but changes only take effect when 1468switched off. Can be changed any time, but changes only take effect when
1260the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1469the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1470.IP "ev_tstamp at [read\-only]" 4
1471.IX Item "ev_tstamp at [read-only]"
1472When active, contains the absolute time that the watcher is supposed to
1473trigger next.
1261.PP 1474.PP
1262Example: Call a callback every hour, or, more precisely, whenever the 1475Example: Call a callback every hour, or, more precisely, whenever the
1263system clock is divisible by 3600. The callback invocation times have 1476system clock is divisible by 3600. The callback invocation times have
1264potentially a lot of jittering, but good long-term stability. 1477potentially a lot of jittering, but good long-term stability.
1265.PP 1478.PP
… …
1315first watcher gets started will libev actually register a signal watcher 1528first watcher gets started will libev actually register a signal watcher
1316with the kernel (thus it coexists with your own signal handlers as long 1529with the kernel (thus it coexists with your own signal handlers as long
1317as you don't register any with libev). Similarly, when the last signal 1530as you don't register any with libev). Similarly, when the last signal
1318watcher for a signal is stopped libev will reset the signal handler to 1531watcher for a signal is stopped libev will reset the signal handler to
1319\&\s-1SIG_DFL\s0 (regardless of what it was set to before). 1532\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
1533.PP
1534\fIWatcher-Specific Functions and Data Members\fR
1535.IX Subsection "Watcher-Specific Functions and Data Members"
1320.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1536.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1321.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1537.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1322.PD 0 1538.PD 0
1323.IP "ev_signal_set (ev_signal *, int signum)" 4 1539.IP "ev_signal_set (ev_signal *, int signum)" 4
1324.IX Item "ev_signal_set (ev_signal *, int signum)" 1540.IX Item "ev_signal_set (ev_signal *, int signum)"
… …
1331.ie n .Sh """ev_child"" \- watch out for process status changes" 1547.ie n .Sh """ev_child"" \- watch out for process status changes"
1332.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 1548.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1333.IX Subsection "ev_child - watch out for process status changes" 1549.IX Subsection "ev_child - watch out for process status changes"
1334Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1550Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1335some child status changes (most typically when a child of yours dies). 1551some child status changes (most typically when a child of yours dies).
1552.PP
1553\fIWatcher-Specific Functions and Data Members\fR
1554.IX Subsection "Watcher-Specific Functions and Data Members"
1336.IP "ev_child_init (ev_child *, callback, int pid)" 4 1555.IP "ev_child_init (ev_child *, callback, int pid)" 4
1337.IX Item "ev_child_init (ev_child *, callback, int pid)" 1556.IX Item "ev_child_init (ev_child *, callback, int pid)"
1338.PD 0 1557.PD 0
1339.IP "ev_child_set (ev_child *, int pid)" 4 1558.IP "ev_child_set (ev_child *, int pid)" 4
1340.IX Item "ev_child_set (ev_child *, int pid)" 1559.IX Item "ev_child_set (ev_child *, int pid)"
… …
1382not exist\*(R" is a status change like any other. The condition \*(L"path does 1601not exist\*(R" is a status change like any other. The condition \*(L"path does
1383not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1602not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1384otherwise always forced to be at least one) and all the other fields of 1603otherwise always forced to be at least one) and all the other fields of
1385the stat buffer having unspecified contents. 1604the stat buffer having unspecified contents.
1386.PP 1605.PP
1606The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1607relative and your working directory changes, the behaviour is undefined.
1608.PP
1387Since there is no standard to do this, the portable implementation simply 1609Since there is no standard to do this, the portable implementation simply
1388calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You 1610calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1389can specify a recommended polling interval for this case. If you specify 1611can specify a recommended polling interval for this case. If you specify
1390a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1612a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1391unspecified default\fR value will be used (which you can expect to be around 1613unspecified default\fR value will be used (which you can expect to be around
… …
1402reader). Inotify will be used to give hints only and should not change the 1624reader). Inotify will be used to give hints only and should not change the
1403semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs 1625semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1404to fall back to regular polling again even with inotify, but changes are 1626to fall back to regular polling again even with inotify, but changes are
1405usually detected immediately, and if the file exists there will be no 1627usually detected immediately, and if the file exists there will be no
1406polling. 1628polling.
1629.PP
1630\fIWatcher-Specific Functions and Data Members\fR
1631.IX Subsection "Watcher-Specific Functions and Data Members"
1407.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1632.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1408.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1633.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1409.PD 0 1634.PD 0
1410.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1635.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1411.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1636.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1472\& ev_stat_start (loop, &passwd); 1697\& ev_stat_start (loop, &passwd);
1473.Ve 1698.Ve
1474.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1699.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1475.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1700.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1476.IX Subsection "ev_idle - when you've got nothing better to do..." 1701.IX Subsection "ev_idle - when you've got nothing better to do..."
1477Idle watchers trigger events when there are no other events are pending 1702Idle watchers trigger events when no other events of the same or higher
1478(prepare, check and other idle watchers do not count). That is, as long 1703priority are pending (prepare, check and other idle watchers do not
1479as your process is busy handling sockets or timeouts (or even signals, 1704count).
1480imagine) it will not be triggered. But when your process is idle all idle 1705.PP
1481watchers are being called again and again, once per event loop iteration \- 1706That is, as long as your process is busy handling sockets or timeouts
1707(or even signals, imagine) of the same or higher priority it will not be
1708triggered. But when your process is idle (or only lower-priority watchers
1709are pending), the idle watchers are being called once per event loop
1482until stopped, that is, or your process receives more events and becomes 1710iteration \- until stopped, that is, or your process receives more events
1483busy. 1711and becomes busy again with higher priority stuff.
1484.PP 1712.PP
1485The most noteworthy effect is that as long as any idle watchers are 1713The most noteworthy effect is that as long as any idle watchers are
1486active, the process will not block when waiting for new events. 1714active, the process will not block when waiting for new events.
1487.PP 1715.PP
1488Apart from keeping your process non-blocking (which is a useful 1716Apart from keeping your process non-blocking (which is a useful
1489effect on its own sometimes), idle watchers are a good place to do 1717effect on its own sometimes), idle watchers are a good place to do
1490\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the 1718\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the
1491event loop has handled all outstanding events. 1719event loop has handled all outstanding events.
1720.PP
1721\fIWatcher-Specific Functions and Data Members\fR
1722.IX Subsection "Watcher-Specific Functions and Data Members"
1492.IP "ev_idle_init (ev_signal *, callback)" 4 1723.IP "ev_idle_init (ev_signal *, callback)" 4
1493.IX Item "ev_idle_init (ev_signal *, callback)" 1724.IX Item "ev_idle_init (ev_signal *, callback)"
1494Initialises and configures the idle watcher \- it has no parameters of any 1725Initialises and configures the idle watcher \- it has no parameters of any
1495kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1726kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1496believe me. 1727believe me.
… …
1551are ready to run (it's actually more complicated: it only runs coroutines 1782are ready to run (it's actually more complicated: it only runs coroutines
1552with priority higher than or equal to the event loop and one coroutine 1783with priority higher than or equal to the event loop and one coroutine
1553of lower priority, but only once, using idle watchers to keep the event 1784of lower priority, but only once, using idle watchers to keep the event
1554loop from blocking if lower-priority coroutines are active, thus mapping 1785loop from blocking if lower-priority coroutines are active, thus mapping
1555low-priority coroutines to idle/background tasks). 1786low-priority coroutines to idle/background tasks).
1787.PP
1788It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1789priority, to ensure that they are being run before any other watchers
1790after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1791too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1792supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers
1793did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other
1794(non\-libev) event loops those other event loops might be in an unusable
1795state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to
1796coexist peacefully with others).
1797.PP
1798\fIWatcher-Specific Functions and Data Members\fR
1799.IX Subsection "Watcher-Specific Functions and Data Members"
1556.IP "ev_prepare_init (ev_prepare *, callback)" 4 1800.IP "ev_prepare_init (ev_prepare *, callback)" 4
1557.IX Item "ev_prepare_init (ev_prepare *, callback)" 1801.IX Item "ev_prepare_init (ev_prepare *, callback)"
1558.PD 0 1802.PD 0
1559.IP "ev_check_init (ev_check *, callback)" 4 1803.IP "ev_check_init (ev_check *, callback)" 4
1560.IX Item "ev_check_init (ev_check *, callback)" 1804.IX Item "ev_check_init (ev_check *, callback)"
1561.PD 1805.PD
1562Initialises and configures the prepare or check watcher \- they have no 1806Initialises and configures the prepare or check watcher \- they have no
1563parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1807parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1564macros, but using them is utterly, utterly and completely pointless. 1808macros, but using them is utterly, utterly and completely pointless.
1565.PP 1809.PP
1566Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1810There are a number of principal ways to embed other event loops or modules
1567and a timeout watcher in a prepare handler, as required by libadns, and 1811into libev. Here are some ideas on how to include libadns into libev
1812(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1813use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1814embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1815into the Glib event loop).
1816.PP
1817Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1568in a check watcher, destroy them and call into libadns. What follows is 1818and in a check watcher, destroy them and call into libadns. What follows
1569pseudo-code only of course: 1819is pseudo-code only of course. This requires you to either use a low
1820priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1821the callbacks for the IO/timeout watchers might not have been called yet.
1570.PP 1822.PP
1571.Vb 2 1823.Vb 2
1572\& static ev_io iow [nfd]; 1824\& static ev_io iow [nfd];
1573\& static ev_timer tw; 1825\& static ev_timer tw;
1574.Ve 1826.Ve
1575.PP 1827.PP
1576.Vb 9 1828.Vb 4
1577\& static void 1829\& static void
1578\& io_cb (ev_loop *loop, ev_io *w, int revents) 1830\& io_cb (ev_loop *loop, ev_io *w, int revents)
1579\& { 1831\& {
1580\& // set the relevant poll flags
1581\& // could also call adns_processreadable etc. here
1582\& struct pollfd *fd = (struct pollfd *)w->data;
1583\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1584\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1585\& } 1832\& }
1586.Ve 1833.Ve
1587.PP 1834.PP
1588.Vb 7 1835.Vb 8
1589\& // create io watchers for each fd and a timer before blocking 1836\& // create io watchers for each fd and a timer before blocking
1590\& static void 1837\& static void
1591\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1838\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1592\& { 1839\& {
1593\& int timeout = 3600000;truct pollfd fds [nfd]; 1840\& int timeout = 3600000;
1841\& struct pollfd fds [nfd];
1594\& // actual code will need to loop here and realloc etc. 1842\& // actual code will need to loop here and realloc etc.
1595\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1843\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1596.Ve 1844.Ve
1597.PP 1845.PP
1598.Vb 3 1846.Vb 3
… …
1600\& ev_timer_init (&tw, 0, timeout * 1e-3); 1848\& ev_timer_init (&tw, 0, timeout * 1e-3);
1601\& ev_timer_start (loop, &tw); 1849\& ev_timer_start (loop, &tw);
1602.Ve 1850.Ve
1603.PP 1851.PP
1604.Vb 6 1852.Vb 6
1605\& // create on ev_io per pollfd 1853\& // create one ev_io per pollfd
1606\& for (int i = 0; i < nfd; ++i) 1854\& for (int i = 0; i < nfd; ++i)
1607\& { 1855\& {
1608\& ev_io_init (iow + i, io_cb, fds [i].fd, 1856\& ev_io_init (iow + i, io_cb, fds [i].fd,
1609\& ((fds [i].events & POLLIN ? EV_READ : 0) 1857\& ((fds [i].events & POLLIN ? EV_READ : 0)
1610\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1858\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1611.Ve 1859.Ve
1612.PP 1860.PP
1613.Vb 5 1861.Vb 4
1614\& fds [i].revents = 0; 1862\& fds [i].revents = 0;
1615\& iow [i].data = fds + i;
1616\& ev_io_start (loop, iow + i); 1863\& ev_io_start (loop, iow + i);
1617\& } 1864\& }
1618\& } 1865\& }
1619.Ve 1866.Ve
1620.PP 1867.PP
… …
1624\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1871\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1625\& { 1872\& {
1626\& ev_timer_stop (loop, &tw); 1873\& ev_timer_stop (loop, &tw);
1627.Ve 1874.Ve
1628.PP 1875.PP
1629.Vb 2 1876.Vb 8
1630\& for (int i = 0; i < nfd; ++i) 1877\& for (int i = 0; i < nfd; ++i)
1878\& {
1879\& // set the relevant poll flags
1880\& // could also call adns_processreadable etc. here
1881\& struct pollfd *fd = fds + i;
1882\& int revents = ev_clear_pending (iow + i);
1883\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1884\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1885.Ve
1886.PP
1887.Vb 3
1888\& // now stop the watcher
1631\& ev_io_stop (loop, iow + i); 1889\& ev_io_stop (loop, iow + i);
1890\& }
1632.Ve 1891.Ve
1633.PP 1892.PP
1634.Vb 2 1893.Vb 2
1635\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1894\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1895\& }
1896.Ve
1897.PP
1898Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1899in the prepare watcher and would dispose of the check watcher.
1900.PP
1901Method 3: If the module to be embedded supports explicit event
1902notification (adns does), you can also make use of the actual watcher
1903callbacks, and only destroy/create the watchers in the prepare watcher.
1904.PP
1905.Vb 5
1906\& static void
1907\& timer_cb (EV_P_ ev_timer *w, int revents)
1908\& {
1909\& adns_state ads = (adns_state)w->data;
1910\& update_now (EV_A);
1911.Ve
1912.PP
1913.Vb 2
1914\& adns_processtimeouts (ads, &tv_now);
1915\& }
1916.Ve
1917.PP
1918.Vb 5
1919\& static void
1920\& io_cb (EV_P_ ev_io *w, int revents)
1921\& {
1922\& adns_state ads = (adns_state)w->data;
1923\& update_now (EV_A);
1924.Ve
1925.PP
1926.Vb 3
1927\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1928\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1929\& }
1930.Ve
1931.PP
1932.Vb 1
1933\& // do not ever call adns_afterpoll
1934.Ve
1935.PP
1936Method 4: Do not use a prepare or check watcher because the module you
1937want to embed is too inflexible to support it. Instead, youc na override
1938their poll function. The drawback with this solution is that the main
1939loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1940this.
1941.PP
1942.Vb 4
1943\& static gint
1944\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1945\& {
1946\& int got_events = 0;
1947.Ve
1948.PP
1949.Vb 2
1950\& for (n = 0; n < nfds; ++n)
1951\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1952.Ve
1953.PP
1954.Vb 2
1955\& if (timeout >= 0)
1956\& // create/start timer
1957.Ve
1958.PP
1959.Vb 2
1960\& // poll
1961\& ev_loop (EV_A_ 0);
1962.Ve
1963.PP
1964.Vb 3
1965\& // stop timer again
1966\& if (timeout >= 0)
1967\& ev_timer_stop (EV_A_ &to);
1968.Ve
1969.PP
1970.Vb 3
1971\& // stop io watchers again - their callbacks should have set
1972\& for (n = 0; n < nfds; ++n)
1973\& ev_io_stop (EV_A_ iow [n]);
1974.Ve
1975.PP
1976.Vb 2
1977\& return got_events;
1636\& } 1978\& }
1637.Ve 1979.Ve
1638.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1980.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1639.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1981.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1640.IX Subsection "ev_embed - when one backend isn't enough..." 1982.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1709\& ev_embed_start (loop_hi, &embed); 2051\& ev_embed_start (loop_hi, &embed);
1710\& } 2052\& }
1711\& else 2053\& else
1712\& loop_lo = loop_hi; 2054\& loop_lo = loop_hi;
1713.Ve 2055.Ve
2056.PP
2057\fIWatcher-Specific Functions and Data Members\fR
2058.IX Subsection "Watcher-Specific Functions and Data Members"
1714.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 2059.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1715.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 2060.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1716.PD 0 2061.PD 0
1717.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 2062.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1718.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 2063.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
… …
1725.IP "ev_embed_sweep (loop, ev_embed *)" 4 2070.IP "ev_embed_sweep (loop, ev_embed *)" 4
1726.IX Item "ev_embed_sweep (loop, ev_embed *)" 2071.IX Item "ev_embed_sweep (loop, ev_embed *)"
1727Make a single, non-blocking sweep over the embedded loop. This works 2072Make a single, non-blocking sweep over the embedded loop. This works
1728similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 2073similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1729apropriate way for embedded loops. 2074apropriate way for embedded loops.
1730.IP "struct ev_loop *loop [read\-only]" 4 2075.IP "struct ev_loop *other [read\-only]" 4
1731.IX Item "struct ev_loop *loop [read-only]" 2076.IX Item "struct ev_loop *other [read-only]"
1732The embedded event loop. 2077The embedded event loop.
1733.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 2078.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1734.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 2079.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1735.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 2080.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1736Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 2081Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
… …
1738\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 2083\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1739event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 2084event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1740and only in the child after the fork. If whoever good citizen calling 2085and only in the child after the fork. If whoever good citizen calling
1741\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 2086\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1742handlers will be invoked, too, of course. 2087handlers will be invoked, too, of course.
2088.PP
2089\fIWatcher-Specific Functions and Data Members\fR
2090.IX Subsection "Watcher-Specific Functions and Data Members"
1743.IP "ev_fork_init (ev_signal *, callback)" 4 2091.IP "ev_fork_init (ev_signal *, callback)" 4
1744.IX Item "ev_fork_init (ev_signal *, callback)" 2092.IX Item "ev_fork_init (ev_signal *, callback)"
1745Initialises and configures the fork watcher \- it has no parameters of any 2093Initialises and configures the fork watcher \- it has no parameters of any
1746kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 2094kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1747believe me. 2095believe me.
… …
1824.PP 2172.PP
1825.Vb 1 2173.Vb 1
1826\& #include <ev++.h> 2174\& #include <ev++.h>
1827.Ve 2175.Ve
1828.PP 2176.PP
1829(it is not installed by default). This automatically includes \fIev.h\fR 2177This automatically includes \fIev.h\fR and puts all of its definitions (many
1830and puts all of its definitions (many of them macros) into the global 2178of them macros) into the global namespace. All \*(C+ specific things are
1831namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2179put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2180options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1832.PP 2181.PP
1833It should support all the same embedding options as \fIev.h\fR, most notably 2182Care has been taken to keep the overhead low. The only data member the \*(C+
1834\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2183classes add (compared to plain C\-style watchers) is the event loop pointer
2184that the watcher is associated with (or no additional members at all if
2185you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2186.PP
2187Currently, functions, and static and non-static member functions can be
2188used as callbacks. Other types should be easy to add as long as they only
2189need one additional pointer for context. If you need support for other
2190types of functors please contact the author (preferably after implementing
2191it).
1835.PP 2192.PP
1836Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2193Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1837.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2194.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1838.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2195.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1839.IX Item "ev::READ, ev::WRITE etc." 2196.IX Item "ev::READ, ev::WRITE etc."
… …
1851which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2208which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1852defines by many implementations. 2209defines by many implementations.
1853.Sp 2210.Sp
1854All of those classes have these methods: 2211All of those classes have these methods:
1855.RS 4 2212.RS 4
1856.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2213.IP "ev::TYPE::TYPE ()" 4
1857.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2214.IX Item "ev::TYPE::TYPE ()"
1858.PD 0 2215.PD 0
1859.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2216.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1860.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2217.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1861.IP "ev::TYPE::~TYPE" 4 2218.IP "ev::TYPE::~TYPE" 4
1862.IX Item "ev::TYPE::~TYPE" 2219.IX Item "ev::TYPE::~TYPE"
1863.PD 2220.PD
1864The constructor takes a pointer to an object and a method pointer to 2221The constructor (optionally) takes an event loop to associate the watcher
1865the event handler callback to call in this class. The constructor calls 2222with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1866\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2223.Sp
1867before starting it. If you do not specify a loop then the constructor 2224The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1868automatically associates the default loop with this watcher. 2225\&\f(CW\*(C`set\*(C'\fR method before starting it.
2226.Sp
2227It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2228method to set a callback before you can start the watcher.
2229.Sp
2230(The reason why you have to use a method is a limitation in \*(C+ which does
2231not allow explicit template arguments for constructors).
1869.Sp 2232.Sp
1870The destructor automatically stops the watcher if it is active. 2233The destructor automatically stops the watcher if it is active.
2234.IP "w\->set<class, &class::method> (object *)" 4
2235.IX Item "w->set<class, &class::method> (object *)"
2236This method sets the callback method to call. The method has to have a
2237signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2238first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2239parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2240.Sp
2241This method synthesizes efficient thunking code to call your method from
2242the C callback that libev requires. If your compiler can inline your
2243callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2244your compiler is good :), then the method will be fully inlined into the
2245thunking function, making it as fast as a direct C callback.
2246.Sp
2247Example: simple class declaration and watcher initialisation
2248.Sp
2249.Vb 4
2250\& struct myclass
2251\& {
2252\& void io_cb (ev::io &w, int revents) { }
2253\& }
2254.Ve
2255.Sp
2256.Vb 3
2257\& myclass obj;
2258\& ev::io iow;
2259\& iow.set <myclass, &myclass::io_cb> (&obj);
2260.Ve
2261.IP "w\->set<function> (void *data = 0)" 4
2262.IX Item "w->set<function> (void *data = 0)"
2263Also sets a callback, but uses a static method or plain function as
2264callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2265\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2266.Sp
2267The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2268.Sp
2269See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2270.Sp
2271Example:
2272.Sp
2273.Vb 2
2274\& static void io_cb (ev::io &w, int revents) { }
2275\& iow.set <io_cb> ();
2276.Ve
1871.IP "w\->set (struct ev_loop *)" 4 2277.IP "w\->set (struct ev_loop *)" 4
1872.IX Item "w->set (struct ev_loop *)" 2278.IX Item "w->set (struct ev_loop *)"
1873Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2279Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1874do this when the watcher is inactive (and not pending either). 2280do this when the watcher is inactive (and not pending either).
1875.IP "w\->set ([args])" 4 2281.IP "w\->set ([args])" 4
1876.IX Item "w->set ([args])" 2282.IX Item "w->set ([args])"
1877Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2283Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1878called at least once. Unlike the C counterpart, an active watcher gets 2284called at least once. Unlike the C counterpart, an active watcher gets
1879automatically stopped and restarted. 2285automatically stopped and restarted when reconfiguring it with this
2286method.
1880.IP "w\->start ()" 4 2287.IP "w\->start ()" 4
1881.IX Item "w->start ()" 2288.IX Item "w->start ()"
1882Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2289Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1883constructor already takes the loop. 2290constructor already stores the event loop.
1884.IP "w\->stop ()" 4 2291.IP "w\->stop ()" 4
1885.IX Item "w->stop ()" 2292.IX Item "w->stop ()"
1886Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2293Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1887.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2294.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4
1888.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2295.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
1889.IX Item "w->again () ev::timer, ev::periodic only" 2296.IX Item "w->again () (ev::timer, ev::periodic only)"
1890For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding 2297For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1891\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2298\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1892.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2299.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
1893.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2300.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
1894.IX Item "w->sweep () ev::embed only" 2301.IX Item "w->sweep () (ev::embed only)"
1895Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2302Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1896.ie n .IP "w\->update () ""ev::stat"" only" 4 2303.ie n .IP "w\->update () (""ev::stat"" only)" 4
1897.el .IP "w\->update () \f(CWev::stat\fR only" 4 2304.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
1898.IX Item "w->update () ev::stat only" 2305.IX Item "w->update () (ev::stat only)"
1899Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. 2306Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1900.RE 2307.RE
1901.RS 4 2308.RS 4
1902.RE 2309.RE
1903.PP 2310.PP
… …
1914.Vb 2 2321.Vb 2
1915\& myclass (); 2322\& myclass ();
1916\& } 2323\& }
1917.Ve 2324.Ve
1918.PP 2325.PP
1919.Vb 6 2326.Vb 4
1920\& myclass::myclass (int fd) 2327\& myclass::myclass (int fd)
1921\& : io (this, &myclass::io_cb),
1922\& idle (this, &myclass::idle_cb)
1923\& { 2328\& {
2329\& io .set <myclass, &myclass::io_cb > (this);
2330\& idle.set <myclass, &myclass::idle_cb> (this);
2331.Ve
2332.PP
2333.Vb 2
1924\& io.start (fd, ev::READ); 2334\& io.start (fd, ev::READ);
1925\& } 2335\& }
1926.Ve 2336.Ve
1927.SH "MACRO MAGIC" 2337.SH "MACRO MAGIC"
1928.IX Header "MACRO MAGIC" 2338.IX Header "MACRO MAGIC"
1929Libev can be compiled with a variety of options, the most fundemantal is 2339Libev can be compiled with a variety of options, the most fundamantal
1930\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2340of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
1931callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2341functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1932.PP 2342.PP
1933To make it easier to write programs that cope with either variant, the 2343To make it easier to write programs that cope with either variant, the
1934following macros are defined: 2344following macros are defined:
1935.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2345.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1936.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 2346.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
… …
1970.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2380.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1971.IX Item "EV_DEFAULT, EV_DEFAULT_" 2381.IX Item "EV_DEFAULT, EV_DEFAULT_"
1972Similar to the other two macros, this gives you the value of the default 2382Similar to the other two macros, this gives you the value of the default
1973loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2383loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1974.PP 2384.PP
1975Example: Declare and initialise a check watcher, working regardless of 2385Example: Declare and initialise a check watcher, utilising the above
1976wether multiple loops are supported or not. 2386macros so it will work regardless of whether multiple loops are supported
2387or not.
1977.PP 2388.PP
1978.Vb 5 2389.Vb 5
1979\& static void 2390\& static void
1980\& check_cb (EV_P_ ev_timer *w, int revents) 2391\& check_cb (EV_P_ ev_timer *w, int revents)
1981\& { 2392\& {
… …
1994Libev can (and often is) directly embedded into host 2405Libev can (and often is) directly embedded into host
1995applications. Examples of applications that embed it include the Deliantra 2406applications. Examples of applications that embed it include the Deliantra
1996Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) 2407Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
1997and rxvt\-unicode. 2408and rxvt\-unicode.
1998.PP 2409.PP
1999The goal is to enable you to just copy the neecssary files into your 2410The goal is to enable you to just copy the necessary files into your
2000source directory without having to change even a single line in them, so 2411source directory without having to change even a single line in them, so
2001you can easily upgrade by simply copying (or having a checked-out copy of 2412you can easily upgrade by simply copying (or having a checked-out copy of
2002libev somewhere in your source tree). 2413libev somewhere in your source tree).
2003.Sh "\s-1FILESETS\s0" 2414.Sh "\s-1FILESETS\s0"
2004.IX Subsection "FILESETS" 2415.IX Subsection "FILESETS"
… …
2044.Vb 1 2455.Vb 1
2045\& ev_win32.c required on win32 platforms only 2456\& ev_win32.c required on win32 platforms only
2046.Ve 2457.Ve
2047.PP 2458.PP
2048.Vb 5 2459.Vb 5
2049\& ev_select.c only when select backend is enabled (which is by default) 2460\& ev_select.c only when select backend is enabled (which is enabled by default)
2050\& ev_poll.c only when poll backend is enabled (disabled by default) 2461\& ev_poll.c only when poll backend is enabled (disabled by default)
2051\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2462\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2052\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2463\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2053\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2464\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2054.Ve 2465.Ve
… …
2109.IX Item "EV_USE_MONOTONIC" 2520.IX Item "EV_USE_MONOTONIC"
2110If defined to be \f(CW1\fR, libev will try to detect the availability of the 2521If defined to be \f(CW1\fR, libev will try to detect the availability of the
2111monotonic clock option at both compiletime and runtime. Otherwise no use 2522monotonic clock option at both compiletime and runtime. Otherwise no use
2112of the monotonic clock option will be attempted. If you enable this, you 2523of the monotonic clock option will be attempted. If you enable this, you
2113usually have to link against librt or something similar. Enabling it when 2524usually have to link against librt or something similar. Enabling it when
2114the functionality isn't available is safe, though, althoguh you have 2525the functionality isn't available is safe, though, although you have
2115to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR 2526to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2116function is hiding in (often \fI\-lrt\fR). 2527function is hiding in (often \fI\-lrt\fR).
2117.IP "\s-1EV_USE_REALTIME\s0" 4 2528.IP "\s-1EV_USE_REALTIME\s0" 4
2118.IX Item "EV_USE_REALTIME" 2529.IX Item "EV_USE_REALTIME"
2119If defined to be \f(CW1\fR, libev will try to detect the availability of the 2530If defined to be \f(CW1\fR, libev will try to detect the availability of the
2120realtime clock option at compiletime (and assume its availability at 2531realtime clock option at compiletime (and assume its availability at
2121runtime if successful). Otherwise no use of the realtime clock option will 2532runtime if successful). Otherwise no use of the realtime clock option will
2122be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get 2533be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2123(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries 2534(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the
2124in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. 2535note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2536.IP "\s-1EV_USE_NANOSLEEP\s0" 4
2537.IX Item "EV_USE_NANOSLEEP"
2538If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available
2539and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR.
2125.IP "\s-1EV_USE_SELECT\s0" 4 2540.IP "\s-1EV_USE_SELECT\s0" 4
2126.IX Item "EV_USE_SELECT" 2541.IX Item "EV_USE_SELECT"
2127If undefined or defined to be \f(CW1\fR, libev will compile in support for the 2542If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2128\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no 2543\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
2129other method takes over, select will be it. Otherwise the select backend 2544other method takes over, select will be it. Otherwise the select backend
… …
2207If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2622If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2208will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2623will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2209additional independent event loops. Otherwise there will be no support 2624additional independent event loops. Otherwise there will be no support
2210for multiple event loops and there is no first event loop pointer 2625for multiple event loops and there is no first event loop pointer
2211argument. Instead, all functions act on the single default loop. 2626argument. Instead, all functions act on the single default loop.
2627.IP "\s-1EV_MINPRI\s0" 4
2628.IX Item "EV_MINPRI"
2629.PD 0
2630.IP "\s-1EV_MAXPRI\s0" 4
2631.IX Item "EV_MAXPRI"
2632.PD
2633The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2634\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2635provide for more priorities by overriding those symbols (usually defined
2636to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2637.Sp
2638When doing priority-based operations, libev usually has to linearly search
2639all the priorities, so having many of them (hundreds) uses a lot of space
2640and time, so using the defaults of five priorities (\-2 .. +2) is usually
2641fine.
2642.Sp
2643If your embedding app does not need any priorities, defining these both to
2644\&\f(CW0\fR will save some memory and cpu.
2212.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2645.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2213.IX Item "EV_PERIODIC_ENABLE" 2646.IX Item "EV_PERIODIC_ENABLE"
2214If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2647If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2648defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2649code.
2650.IP "\s-1EV_IDLE_ENABLE\s0" 4
2651.IX Item "EV_IDLE_ENABLE"
2652If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2215defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2653defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2216code. 2654code.
2217.IP "\s-1EV_EMBED_ENABLE\s0" 4 2655.IP "\s-1EV_EMBED_ENABLE\s0" 4
2218.IX Item "EV_EMBED_ENABLE" 2656.IX Item "EV_EMBED_ENABLE"
2219If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2657If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2266.IP "ev_set_cb (ev, cb)" 4 2704.IP "ev_set_cb (ev, cb)" 4
2267.IX Item "ev_set_cb (ev, cb)" 2705.IX Item "ev_set_cb (ev, cb)"
2268.PD 2706.PD
2269Can be used to change the callback member declaration in each watcher, 2707Can be used to change the callback member declaration in each watcher,
2270and the way callbacks are invoked and set. Must expand to a struct member 2708and the way callbacks are invoked and set. Must expand to a struct member
2271definition and a statement, respectively. See the \fIev.v\fR header file for 2709definition and a statement, respectively. See the \fIev.h\fR header file for
2272their default definitions. One possible use for overriding these is to 2710their default definitions. One possible use for overriding these is to
2273avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 2711avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2274method calls instead of plain function calls in \*(C+. 2712method calls instead of plain function calls in \*(C+.
2713.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
2714.IX Subsection "EXPORTED API SYMBOLS"
2715If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of
2716exported symbols, you can use the provided \fISymbol.*\fR files which list
2717all public symbols, one per line:
2718.Sp
2719.Vb 2
2720\& Symbols.ev for libev proper
2721\& Symbols.event for the libevent emulation
2722.Ve
2723.Sp
2724This can also be used to rename all public symbols to avoid clashes with
2725multiple versions of libev linked together (which is obviously bad in
2726itself, but sometimes it is inconvinient to avoid this).
2727.Sp
2728A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
2729include before including \fIev.h\fR:
2730.Sp
2731.Vb 1
2732\& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
2733.Ve
2734.Sp
2735This would create a file \fIwrap.h\fR which essentially looks like this:
2736.Sp
2737.Vb 4
2738\& #define ev_backend myprefix_ev_backend
2739\& #define ev_check_start myprefix_ev_check_start
2740\& #define ev_check_stop myprefix_ev_check_stop
2741\& ...
2742.Ve
2275.Sh "\s-1EXAMPLES\s0" 2743.Sh "\s-1EXAMPLES\s0"
2276.IX Subsection "EXAMPLES" 2744.IX Subsection "EXAMPLES"
2277For a real-world example of a program the includes libev 2745For a real-world example of a program the includes libev
2278verbatim, you can have a look at the \s-1EV\s0 perl module 2746verbatim, you can have a look at the \s-1EV\s0 perl module
2279(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2747(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
… …
2281interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2749interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2282will be compiled. It is pretty complex because it provides its own header 2750will be compiled. It is pretty complex because it provides its own header
2283file. 2751file.
2284.Sp 2752.Sp
2285The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2753The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2286that everybody includes and which overrides some autoconf choices: 2754that everybody includes and which overrides some configure choices:
2287.Sp 2755.Sp
2288.Vb 4 2756.Vb 9
2757\& #define EV_MINIMAL 1
2289\& #define EV_USE_POLL 0 2758\& #define EV_USE_POLL 0
2290\& #define EV_MULTIPLICITY 0 2759\& #define EV_MULTIPLICITY 0
2291\& #define EV_PERIODICS 0 2760\& #define EV_PERIODIC_ENABLE 0
2761\& #define EV_STAT_ENABLE 0
2762\& #define EV_FORK_ENABLE 0
2292\& #define EV_CONFIG_H <config.h> 2763\& #define EV_CONFIG_H <config.h>
2764\& #define EV_MINPRI 0
2765\& #define EV_MAXPRI 0
2293.Ve 2766.Ve
2294.Sp 2767.Sp
2295.Vb 1 2768.Vb 1
2296\& #include "ev++.h" 2769\& #include "ev++.h"
2297.Ve 2770.Ve
… …
2305.SH "COMPLEXITIES" 2778.SH "COMPLEXITIES"
2306.IX Header "COMPLEXITIES" 2779.IX Header "COMPLEXITIES"
2307In this section the complexities of (many of) the algorithms used inside 2780In this section the complexities of (many of) the algorithms used inside
2308libev will be explained. For complexity discussions about backends see the 2781libev will be explained. For complexity discussions about backends see the
2309documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2782documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2783.Sp
2784All of the following are about amortised time: If an array needs to be
2785extended, libev needs to realloc and move the whole array, but this
2786happens asymptotically never with higher number of elements, so O(1) might
2787mean it might do a lengthy realloc operation in rare cases, but on average
2788it is much faster and asymptotically approaches constant time.
2310.RS 4 2789.RS 4
2311.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2790.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2312.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2791.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2313.PD 0 2792This means that, when you have a watcher that triggers in one hour and
2793there are 100 watchers that would trigger before that then inserting will
2794have to skip those 100 watchers.
2314.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2795.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2315.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2796.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2797That means that for changing a timer costs less than removing/adding them
2798as only the relative motion in the event queue has to be paid for.
2316.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2799.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2317.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2800.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2318.IP "Stopping check/prepare/idle watchers: O(1)" 4 2801These just add the watcher into an array or at the head of a list.
2319.IX Item "Stopping check/prepare/idle watchers: O(1)" 2802=item Stopping check/prepare/idle watchers: O(1)
2320.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 2803.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2321.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" 2804.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2805These watchers are stored in lists then need to be walked to find the
2806correct watcher to remove. The lists are usually short (you don't usually
2807have many watchers waiting for the same fd or signal).
2322.IP "Finding the next timer per loop iteration: O(1)" 4 2808.IP "Finding the next timer per loop iteration: O(1)" 4
2323.IX Item "Finding the next timer per loop iteration: O(1)" 2809.IX Item "Finding the next timer per loop iteration: O(1)"
2810.PD 0
2324.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2811.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2325.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2812.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2813.PD
2814A change means an I/O watcher gets started or stopped, which requires
2815libev to recalculate its status (and possibly tell the kernel).
2326.IP "Activating one watcher: O(1)" 4 2816.IP "Activating one watcher: O(1)" 4
2327.IX Item "Activating one watcher: O(1)" 2817.IX Item "Activating one watcher: O(1)"
2818.PD 0
2819.IP "Priority handling: O(number_of_priorities)" 4
2820.IX Item "Priority handling: O(number_of_priorities)"
2821.PD
2822Priorities are implemented by allocating some space for each
2823priority. When doing priority-based operations, libev usually has to
2824linearly search all the priorities.
2328.RE 2825.RE
2329.RS 4 2826.RS 4
2330.PD
2331.SH "AUTHOR" 2827.SH "AUTHOR"
2332.IX Header "AUTHOR" 2828.IX Header "AUTHOR"
2333Marc Lehmann <libev@schmorp.de>. 2829Marc Lehmann <libev@schmorp.de>.

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