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Revision 1.27 by root, Tue Nov 27 20:15:01 2007 UTC vs.
Revision 1.47 by root, Sun Dec 9 19:46:56 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-09" "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
138\& #include <ev.h>
139.Ve
140.SH "EXAMPLE PROGRAM"
141.IX Header "EXAMPLE PROGRAM"
142.Vb 1
143\& #include <ev.h>
144.Ve
145.PP
137.Vb 2 146.Vb 2
138\& /* this is the only header you need */
139\& #include <ev.h>
140.Ve
141.PP
142.Vb 3
143\& /* what follows is a fully working example program */
144\& ev_io stdin_watcher; 147\& ev_io stdin_watcher;
145\& ev_timer timeout_watcher; 148\& ev_timer timeout_watcher;
146.Ve 149.Ve
147.PP 150.PP
148.Vb 8 151.Vb 8
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193\& return 0; 196\& return 0;
194\& } 197\& }
195.Ve 198.Ve
196.SH "DESCRIPTION" 199.SH "DESCRIPTION"
197.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
198Libev 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
199file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occuring), and it will manage
200these event sources and provide your program with events. 207these event sources and provide your program with events.
201.PP 208.PP
202To 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
… …
207watchers\fR, which are relatively small C structures you initialise with the 214watchers\fR, which are relatively small C structures you initialise with the
208details 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
209watcher. 216watcher.
210.SH "FEATURES" 217.SH "FEATURES"
211.IX Header "FEATURES" 218.IX Header "FEATURES"
212Libev supports select, poll, the linux-specific epoll and the bsd-specific 219Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
213kqueue mechanisms for file descriptor events, relative timers, absolute 220BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
214timers with customised rescheduling, signal events, process status change 221for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
215events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 222(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
216loop mechanism itself (idle, prepare and check watchers). It also is quite 223with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
217fast (see this benchmark comparing 224(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
218it to libevent for example). 225watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
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
227file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
228(\f(CW\*(C`ev_fork\*(C'\fR).
229.PP
230It also is quite fast (see this
231benchmark comparing it to libevent
232for example).
219.SH "CONVENTIONS" 233.SH "CONVENTIONS"
220.IX Header "CONVENTIONS" 234.IX Header "CONVENTIONS"
221Libev is very configurable. In this manual the default configuration 235Libev is very configurable. In this manual the default configuration will
222will be described, which supports multiple event loops. For more info 236be described, which supports multiple event loops. For more info about
223about various configuration options please have a look at the file 237various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
224\&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without 238this manual. If libev was configured without support for multiple event
225support for multiple event loops, then all functions taking an initial 239loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
226argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) 240(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
227will not have this argument.
228.SH "TIME REPRESENTATION" 241.SH "TIME REPRESENTATION"
229.IX Header "TIME REPRESENTATION" 242.IX Header "TIME REPRESENTATION"
230Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
231(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
232the 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
… …
246.IX Item "int ev_version_major ()" 259.IX Item "int ev_version_major ()"
247.PD 0 260.PD 0
248.IP "int ev_version_minor ()" 4 261.IP "int ev_version_minor ()" 4
249.IX Item "int ev_version_minor ()" 262.IX Item "int ev_version_minor ()"
250.PD 263.PD
251You can find out the major and minor version numbers of the library 264You can find out the major and minor \s-1API/ABI\s0 version numbers of the library
252you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 265you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
253\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 266\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
254symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 267symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
255version of the library your program was compiled against. 268version of the library your program was compiled against.
256.Sp 269.Sp
270These version numbers refer to the \s-1API\s0 and \s-1ABI\s0 version of the library, not
271the release version.
272.Sp
257Usually, it's a good idea to terminate if the major versions mismatch, 273Usually, it's a good idea to terminate if the major versions mismatch,
258as this indicates an incompatible change. Minor versions are usually 274as this indicates an incompatible change. Minor versions are usually
259compatible to older versions, so a larger minor version alone is usually 275compatible to older versions, so a larger minor version alone is usually
260not a problem. 276not a problem.
261.Sp 277.Sp
262Example: make sure we haven't accidentally been linked against the wrong 278Example: Make sure we haven't accidentally been linked against the wrong
263version: 279version.
264.Sp 280.Sp
265.Vb 3 281.Vb 3
266\& assert (("libev version mismatch", 282\& assert (("libev version mismatch",
267\& ev_version_major () == EV_VERSION_MAJOR 283\& ev_version_major () == EV_VERSION_MAJOR
268\& && ev_version_minor () >= EV_VERSION_MINOR)); 284\& && ev_version_minor () >= EV_VERSION_MINOR));
… …
296might be supported on the current system, you would need to look at 312might be supported on the current system, you would need to look at
297\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for 313\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
298recommended ones. 314recommended ones.
299.Sp 315.Sp
300See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 316See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
301.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 317.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
302.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 318.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
303Sets the allocation function to use (the prototype and semantics are 319Sets the allocation function to use (the prototype is similar \- the
304identical to the realloc C function). It is used to allocate and free 320semantics is identical \- to the realloc C function). It is used to
305memory (no surprises here). If it returns zero when memory needs to be 321allocate and free memory (no surprises here). If it returns zero when
306allocated, the library might abort or take some potentially destructive 322memory needs to be allocated, the library might abort or take some
307action. The default is your system realloc function. 323potentially destructive action. The default is your system realloc
324function.
308.Sp 325.Sp
309You could override this function in high-availability programs to, say, 326You could override this function in high-availability programs to, say,
310free some memory if it cannot allocate memory, to use a special allocator, 327free some memory if it cannot allocate memory, to use a special allocator,
311or even to sleep a while and retry until some memory is available. 328or even to sleep a while and retry until some memory is available.
312.Sp 329.Sp
313Example: replace the libev allocator with one that waits a bit and then 330Example: Replace the libev allocator with one that waits a bit and then
314retries: better than mine). 331retries).
315.Sp 332.Sp
316.Vb 6 333.Vb 6
317\& static void * 334\& static void *
318\& persistent_realloc (void *ptr, size_t size) 335\& persistent_realloc (void *ptr, size_t size)
319\& { 336\& {
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345callback is set, then libev will expect it to remedy the sitution, no 362callback is set, then libev will expect it to remedy the sitution, no
346matter what, when it returns. That is, libev will generally retry the 363matter what, when it returns. That is, libev will generally retry the
347requested operation, or, if the condition doesn't go away, do bad stuff 364requested operation, or, if the condition doesn't go away, do bad stuff
348(such as abort). 365(such as abort).
349.Sp 366.Sp
350Example: do the same thing as libev does internally: 367Example: This is basically the same thing that libev does internally, too.
351.Sp 368.Sp
352.Vb 6 369.Vb 6
353\& static void 370\& static void
354\& fatal_error (const char *msg) 371\& fatal_error (const char *msg)
355\& { 372\& {
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401or setgid) then libev will \fInot\fR look at the environment variable 418or setgid) then libev will \fInot\fR look at the environment variable
402\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 419\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
403override the flags completely if it is found in the environment. This is 420override the flags completely if it is found in the environment. This is
404useful to try out specific backends to test their performance, or to work 421useful to try out specific backends to test their performance, or to work
405around bugs. 422around bugs.
423.ie n .IP """EVFLAG_FORKCHECK""" 4
424.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
425.IX Item "EVFLAG_FORKCHECK"
426Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
427a fork, you can also make libev check for a fork in each iteration by
428enabling this flag.
429.Sp
430This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
431and thus this might slow down your event loop if you do a lot of loop
432iterations and little real work, but is usually not noticeable (on my
433Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
434without a syscall and thus \fIvery\fR fast, but my Linux system also has
435\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
436.Sp
437The big advantage of this flag is that you can forget about fork (and
438forget about forgetting to tell libev about forking) when you use this
439flag.
440.Sp
441This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
442environment variable.
406.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 443.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
407.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 444.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
408.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 445.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
409This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 446This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
410libev tries to roll its own fd_set with no limits on the number of fds, 447libev tries to roll its own fd_set with no limits on the number of fds,
… …
504Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 541Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
505always distinct from the default loop. Unlike the default loop, it cannot 542always distinct from the default loop. Unlike the default loop, it cannot
506handle signal and child watchers, and attempts to do so will be greeted by 543handle signal and child watchers, and attempts to do so will be greeted by
507undefined behaviour (or a failed assertion if assertions are enabled). 544undefined behaviour (or a failed assertion if assertions are enabled).
508.Sp 545.Sp
509Example: try to create a event loop that uses epoll and nothing else. 546Example: Try to create a event loop that uses epoll and nothing else.
510.Sp 547.Sp
511.Vb 3 548.Vb 3
512\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 549\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
513\& if (!epoller) 550\& if (!epoller)
514\& fatal ("no epoll found here, maybe it hides under your chair"); 551\& fatal ("no epoll found here, maybe it hides under your chair");
… …
551.IP "ev_loop_fork (loop)" 4 588.IP "ev_loop_fork (loop)" 4
552.IX Item "ev_loop_fork (loop)" 589.IX Item "ev_loop_fork (loop)"
553Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 590Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
554\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 591\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
555after fork, and how you do this is entirely your own problem. 592after fork, and how you do this is entirely your own problem.
593.IP "unsigned int ev_loop_count (loop)" 4
594.IX Item "unsigned int ev_loop_count (loop)"
595Returns the count of loop iterations for the loop, which is identical to
596the number of times libev did poll for new events. It starts at \f(CW0\fR and
597happily wraps around with enough iterations.
598.Sp
599This value can sometimes be useful as a generation counter of sorts (it
600\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
601\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
556.IP "unsigned int ev_backend (loop)" 4 602.IP "unsigned int ev_backend (loop)" 4
557.IX Item "unsigned int ev_backend (loop)" 603.IX Item "unsigned int ev_backend (loop)"
558Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 604Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
559use. 605use.
560.IP "ev_tstamp ev_now (loop)" 4 606.IP "ev_tstamp ev_now (loop)" 4
… …
591libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 637libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
592usually a better approach for this kind of thing. 638usually a better approach for this kind of thing.
593.Sp 639.Sp
594Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 640Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
595.Sp 641.Sp
596.Vb 18 642.Vb 19
643\& - Before the first iteration, call any pending watchers.
597\& * If there are no active watchers (reference count is zero), return. 644\& * If there are no active watchers (reference count is zero), return.
598\& - Queue prepare watchers and then call all outstanding watchers. 645\& - Queue all prepare watchers and then call all outstanding watchers.
599\& - If we have been forked, recreate the kernel state. 646\& - If we have been forked, recreate the kernel state.
600\& - Update the kernel state with all outstanding changes. 647\& - Update the kernel state with all outstanding changes.
601\& - Update the "event loop time". 648\& - Update the "event loop time".
602\& - Calculate for how long to block. 649\& - Calculate for how long to block.
603\& - Block the process, waiting for any events. 650\& - Block the process, waiting for any events.
… …
612\& be handled here by queueing them when their watcher gets executed. 659\& be handled here by queueing them when their watcher gets executed.
613\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 660\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
614\& were used, return, otherwise continue with step *. 661\& were used, return, otherwise continue with step *.
615.Ve 662.Ve
616.Sp 663.Sp
617Example: queue some jobs and then loop until no events are outsanding 664Example: Queue some jobs and then loop until no events are outsanding
618anymore. 665anymore.
619.Sp 666.Sp
620.Vb 4 667.Vb 4
621\& ... queue jobs here, make sure they register event watchers as long 668\& ... queue jobs here, make sure they register event watchers as long
622\& ... as they still have work to do (even an idle watcher will do..) 669\& ... as they still have work to do (even an idle watcher will do..)
… …
644visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 691visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
645no event watchers registered by it are active. It is also an excellent 692no event watchers registered by it are active. It is also an excellent
646way to do this for generic recurring timers or from within third-party 693way to do this for generic recurring timers or from within third-party
647libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 694libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
648.Sp 695.Sp
649Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 696Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
650running when nothing else is active. 697running when nothing else is active.
651.Sp 698.Sp
652.Vb 4 699.Vb 4
653\& struct dv_signal exitsig; 700\& struct ev_signal exitsig;
654\& ev_signal_init (&exitsig, sig_cb, SIGINT); 701\& ev_signal_init (&exitsig, sig_cb, SIGINT);
655\& ev_signal_start (myloop, &exitsig); 702\& ev_signal_start (loop, &exitsig);
656\& evf_unref (myloop); 703\& evf_unref (loop);
657.Ve 704.Ve
658.Sp 705.Sp
659Example: for some weird reason, unregister the above signal handler again. 706Example: For some weird reason, unregister the above signal handler again.
660.Sp 707.Sp
661.Vb 2 708.Vb 2
662\& ev_ref (myloop); 709\& ev_ref (loop);
663\& ev_signal_stop (myloop, &exitsig); 710\& ev_signal_stop (loop, &exitsig);
664.Ve 711.Ve
665.SH "ANATOMY OF A WATCHER" 712.SH "ANATOMY OF A WATCHER"
666.IX Header "ANATOMY OF A WATCHER" 713.IX Header "ANATOMY OF A WATCHER"
667A watcher is a structure that you create and register to record your 714A watcher is a structure that you create and register to record your
668interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 715interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
846.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 893.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
847.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 894.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
848Returns a true value iff the watcher is pending, (i.e. it has outstanding 895Returns a true value iff the watcher is pending, (i.e. it has outstanding
849events but its callback has not yet been invoked). As long as a watcher 896events but its callback has not yet been invoked). As long as a watcher
850is pending (but not active) you must not call an init function on it (but 897is pending (but not active) you must not call an init function on it (but
851\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 898\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
852libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 899make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
900it).
853.IP "callback = ev_cb (ev_TYPE *watcher)" 4 901.IP "callback ev_cb (ev_TYPE *watcher)" 4
854.IX Item "callback = ev_cb (ev_TYPE *watcher)" 902.IX Item "callback ev_cb (ev_TYPE *watcher)"
855Returns the callback currently set on the watcher. 903Returns the callback currently set on the watcher.
856.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 904.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
857.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 905.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
858Change the callback. You can change the callback at virtually any time 906Change the callback. You can change the callback at virtually any time
859(modulo threads). 907(modulo threads).
908.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
909.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
910.PD 0
911.IP "int ev_priority (ev_TYPE *watcher)" 4
912.IX Item "int ev_priority (ev_TYPE *watcher)"
913.PD
914Set and query the priority of the watcher. The priority is a small
915integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
916(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
917before watchers with lower priority, but priority will not keep watchers
918from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
919.Sp
920This means that priorities are \fIonly\fR used for ordering callback
921invocation after new events have been received. This is useful, for
922example, to reduce latency after idling, or more often, to bind two
923watchers on the same event and make sure one is called first.
924.Sp
925If you need to suppress invocation when higher priority events are pending
926you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
927.Sp
928You \fImust not\fR change the priority of a watcher as long as it is active or
929pending.
930.Sp
931The default priority used by watchers when no priority has been set is
932always \f(CW0\fR, which is supposed to not be too high and not be too low :).
933.Sp
934Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
935fine, as long as you do not mind that the priority value you query might
936or might not have been adjusted to be within valid range.
937.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
938.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
939Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
940\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
941can deal with that fact.
942.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
943.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
944If the watcher is pending, this function returns clears its pending status
945and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
946watcher isn't pending it does nothing and returns \f(CW0\fR.
860.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 947.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
861.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 948.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
862Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 949Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
863and read at any time, libev will completely ignore it. This can be used 950and read at any time, libev will completely ignore it. This can be used
864to associate arbitrary data with your watcher. If you need more data and 951to associate arbitrary data with your watcher. If you need more data and
… …
885\& struct my_io *w = (struct my_io *)w_; 972\& struct my_io *w = (struct my_io *)w_;
886\& ... 973\& ...
887\& } 974\& }
888.Ve 975.Ve
889.PP 976.PP
890More interesting and less C\-conformant ways of catsing your callback type 977More interesting and less C\-conformant ways of casting your callback type
891have been omitted.... 978instead have been omitted.
979.PP
980Another common scenario is having some data structure with multiple
981watchers:
982.PP
983.Vb 6
984\& struct my_biggy
985\& {
986\& int some_data;
987\& ev_timer t1;
988\& ev_timer t2;
989\& }
990.Ve
991.PP
992In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
993you need to use \f(CW\*(C`offsetof\*(C'\fR:
994.PP
995.Vb 1
996\& #include <stddef.h>
997.Ve
998.PP
999.Vb 6
1000\& static void
1001\& t1_cb (EV_P_ struct ev_timer *w, int revents)
1002\& {
1003\& struct my_biggy big = (struct my_biggy *
1004\& (((char *)w) - offsetof (struct my_biggy, t1));
1005\& }
1006.Ve
1007.PP
1008.Vb 6
1009\& static void
1010\& t2_cb (EV_P_ struct ev_timer *w, int revents)
1011\& {
1012\& struct my_biggy big = (struct my_biggy *
1013\& (((char *)w) - offsetof (struct my_biggy, t2));
1014\& }
1015.Ve
892.SH "WATCHER TYPES" 1016.SH "WATCHER TYPES"
893.IX Header "WATCHER TYPES" 1017.IX Header "WATCHER TYPES"
894This section describes each watcher in detail, but will not repeat 1018This section describes each watcher in detail, but will not repeat
895information given in the last section. Any initialisation/set macros, 1019information given in the last section. Any initialisation/set macros,
896functions and members specific to the watcher type are explained. 1020functions and members specific to the watcher type are explained.
… …
938it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1062it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
939\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1063\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
940.PP 1064.PP
941If you cannot run the fd in non-blocking mode (for example you should not 1065If you cannot run the fd in non-blocking mode (for example you should not
942play around with an Xlib connection), then you have to seperately re-test 1066play around with an Xlib connection), then you have to seperately re-test
943wether a file descriptor is really ready with a known-to-be good interface 1067whether a file descriptor is really ready with a known-to-be good interface
944such as poll (fortunately in our Xlib example, Xlib already does this on 1068such as poll (fortunately in our Xlib example, Xlib already does this on
945its own, so its quite safe to use). 1069its own, so its quite safe to use).
946.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1070.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
947.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1071.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
948.PD 0 1072.PD 0
… …
957The file descriptor being watched. 1081The file descriptor being watched.
958.IP "int events [read\-only]" 4 1082.IP "int events [read\-only]" 4
959.IX Item "int events [read-only]" 1083.IX Item "int events [read-only]"
960The events being watched. 1084The events being watched.
961.PP 1085.PP
962Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1086Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
963readable, but only once. Since it is likely line\-buffered, you could 1087readable, but only once. Since it is likely line\-buffered, you could
964attempt to read a whole line in the callback: 1088attempt to read a whole line in the callback.
965.PP 1089.PP
966.Vb 6 1090.Vb 6
967\& static void 1091\& static void
968\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1092\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
969\& { 1093\& {
… …
1024.IP "ev_timer_again (loop)" 4 1148.IP "ev_timer_again (loop)" 4
1025.IX Item "ev_timer_again (loop)" 1149.IX Item "ev_timer_again (loop)"
1026This will act as if the timer timed out and restart it again if it is 1150This will act as if the timer timed out and restart it again if it is
1027repeating. The exact semantics are: 1151repeating. The exact semantics are:
1028.Sp 1152.Sp
1153If the timer is pending, its pending status is cleared.
1154.Sp
1029If the timer is started but nonrepeating, stop it. 1155If the timer is started but nonrepeating, stop it (as if it timed out).
1030.Sp 1156.Sp
1031If the timer is repeating, either start it if necessary (with the repeat 1157If the timer is repeating, either start it if necessary (with the
1032value), or reset the running timer to the repeat value. 1158\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1033.Sp 1159.Sp
1034This sounds a bit complicated, but here is a useful and typical 1160This sounds a bit complicated, but here is a useful and typical
1035example: Imagine you have a tcp connection and you want a so-called 1161example: Imagine you have a tcp connection and you want a so-called idle
1036idle timeout, that is, you want to be called when there have been, 1162timeout, that is, you want to be called when there have been, say, 60
1037say, 60 seconds of inactivity on the socket. The easiest way to do 1163seconds of inactivity on the socket. The easiest way to do this is to
1038this 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 1164configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1039\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1165\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1040you go into an idle state where you do not expect data to travel on the 1166you go into an idle state where you do not expect data to travel on the
1041socket, you can stop the timer, and again will automatically restart it if 1167socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1042need be. 1168automatically restart it if need be.
1043.Sp 1169.Sp
1044You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1170That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1045and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1171altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1046.Sp 1172.Sp
1047.Vb 8 1173.Vb 8
1048\& ev_timer_init (timer, callback, 0., 5.); 1174\& ev_timer_init (timer, callback, 0., 5.);
1049\& ev_timer_again (loop, timer); 1175\& ev_timer_again (loop, timer);
1050\& ... 1176\& ...
… …
1053\& ... 1179\& ...
1054\& timer->again = 10.; 1180\& timer->again = 10.;
1055\& ev_timer_again (loop, timer); 1181\& ev_timer_again (loop, timer);
1056.Ve 1182.Ve
1057.Sp 1183.Sp
1058This is more efficient then stopping/starting the timer eahc time you want 1184This is more slightly efficient then stopping/starting the timer each time
1059to modify its timeout value. 1185you want to modify its timeout value.
1060.IP "ev_tstamp repeat [read\-write]" 4 1186.IP "ev_tstamp repeat [read\-write]" 4
1061.IX Item "ev_tstamp repeat [read-write]" 1187.IX Item "ev_tstamp repeat [read-write]"
1062The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1188The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1063or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1189or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1064which is also when any modifications are taken into account. 1190which is also when any modifications are taken into account.
1065.PP 1191.PP
1066Example: create a timer that fires after 60 seconds. 1192Example: Create a timer that fires after 60 seconds.
1067.PP 1193.PP
1068.Vb 5 1194.Vb 5
1069\& static void 1195\& static void
1070\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1196\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1071\& { 1197\& {
… …
1077\& struct ev_timer mytimer; 1203\& struct ev_timer mytimer;
1078\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1204\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1079\& ev_timer_start (loop, &mytimer); 1205\& ev_timer_start (loop, &mytimer);
1080.Ve 1206.Ve
1081.PP 1207.PP
1082Example: create a timeout timer that times out after 10 seconds of 1208Example: Create a timeout timer that times out after 10 seconds of
1083inactivity. 1209inactivity.
1084.PP 1210.PP
1085.Vb 5 1211.Vb 5
1086\& static void 1212\& static void
1087\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1213\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
1112but on wallclock time (absolute time). You can tell a periodic watcher 1238but on wallclock time (absolute time). You can tell a periodic watcher
1113to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1239to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1114periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1240periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1115+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1241+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1116take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1242take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1117roughly 10 seconds later and of course not if you reset your system time 1243roughly 10 seconds later).
1118again).
1119.PP 1244.PP
1120They can also be used to implement vastly more complex timers, such as 1245They can also be used to implement vastly more complex timers, such as
1121triggering an event on eahc midnight, local time. 1246triggering an event on each midnight, local time or other, complicated,
1247rules.
1122.PP 1248.PP
1123As with timers, the callback is guarenteed to be invoked only when the 1249As with timers, the callback is guarenteed to be invoked only when the
1124time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1250time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1125during the same loop iteration then order of execution is undefined. 1251during the same loop iteration then order of execution is undefined.
1126.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1252.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
… …
1130.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1256.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1131.PD 1257.PD
1132Lots of arguments, lets sort it out... There are basically three modes of 1258Lots of arguments, lets sort it out... There are basically three modes of
1133operation, and we will explain them from simplest to complex: 1259operation, and we will explain them from simplest to complex:
1134.RS 4 1260.RS 4
1135.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1261.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1136.IX Item "absolute timer (interval = reschedule_cb = 0)" 1262.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1137In this configuration the watcher triggers an event at the wallclock time 1263In this configuration the watcher triggers an event at the wallclock time
1138\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1264\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1139that is, if it is to be run at January 1st 2011 then it will run when the 1265that is, if it is to be run at January 1st 2011 then it will run when the
1140system time reaches or surpasses this time. 1266system time reaches or surpasses this time.
1141.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1267.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1142.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1268.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1143In this mode the watcher will always be scheduled to time out at the next 1269In this mode the watcher will always be scheduled to time out at the next
1144\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1270\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1145of any time jumps. 1271and then repeat, regardless of any time jumps.
1146.Sp 1272.Sp
1147This can be used to create timers that do not drift with respect to system 1273This can be used to create timers that do not drift with respect to system
1148time: 1274time:
1149.Sp 1275.Sp
1150.Vb 1 1276.Vb 1
… …
1157by 3600. 1283by 3600.
1158.Sp 1284.Sp
1159Another way to think about it (for the mathematically inclined) is that 1285Another way to think about it (for the mathematically inclined) is that
1160\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1286\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1161time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1287time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1288.Sp
1289For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1290\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1291this value.
1162.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1292.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1163.IX Item "manual reschedule mode (reschedule_cb = callback)" 1293.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1164In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1294In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1165ignored. Instead, each time the periodic watcher gets scheduled, the 1295ignored. Instead, each time the periodic watcher gets scheduled, the
1166reschedule callback will be called with the watcher as first, and the 1296reschedule callback will be called with the watcher as first, and the
1167current time as second argument. 1297current time as second argument.
1168.Sp 1298.Sp
1169\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1299\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1170ever, or make any event loop modifications\fR. If you need to stop it, 1300ever, or make any event loop modifications\fR. If you need to stop it,
1171return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1301return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1172starting a prepare watcher). 1302starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1173.Sp 1303.Sp
1174Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1304Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1175ev_tstamp now)\*(C'\fR, e.g.: 1305ev_tstamp now)\*(C'\fR, e.g.:
1176.Sp 1306.Sp
1177.Vb 4 1307.Vb 4
… …
1201.IX Item "ev_periodic_again (loop, ev_periodic *)" 1331.IX Item "ev_periodic_again (loop, ev_periodic *)"
1202Simply stops and restarts the periodic watcher again. This is only useful 1332Simply stops and restarts the periodic watcher again. This is only useful
1203when you changed some parameters or the reschedule callback would return 1333when you changed some parameters or the reschedule callback would return
1204a different time than the last time it was called (e.g. in a crond like 1334a different time than the last time it was called (e.g. in a crond like
1205program when the crontabs have changed). 1335program when the crontabs have changed).
1336.IP "ev_tstamp offset [read\-write]" 4
1337.IX Item "ev_tstamp offset [read-write]"
1338When repeating, this contains the offset value, otherwise this is the
1339absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1340.Sp
1341Can be modified any time, but changes only take effect when the periodic
1342timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1206.IP "ev_tstamp interval [read\-write]" 4 1343.IP "ev_tstamp interval [read\-write]" 4
1207.IX Item "ev_tstamp interval [read-write]" 1344.IX Item "ev_tstamp interval [read-write]"
1208The current interval value. Can be modified any time, but changes only 1345The current interval value. Can be modified any time, but changes only
1209take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1346take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1210called. 1347called.
… …
1212.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1349.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1213The current reschedule callback, or \f(CW0\fR, if this functionality is 1350The current reschedule callback, or \f(CW0\fR, if this functionality is
1214switched off. Can be changed any time, but changes only take effect when 1351switched off. Can be changed any time, but changes only take effect when
1215the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1352the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1216.PP 1353.PP
1217Example: call a callback every hour, or, more precisely, whenever the 1354Example: Call a callback every hour, or, more precisely, whenever the
1218system clock is divisible by 3600. The callback invocation times have 1355system clock is divisible by 3600. The callback invocation times have
1219potentially a lot of jittering, but good long-term stability. 1356potentially a lot of jittering, but good long-term stability.
1220.PP 1357.PP
1221.Vb 5 1358.Vb 5
1222\& static void 1359\& static void
… …
1230\& struct ev_periodic hourly_tick; 1367\& struct ev_periodic hourly_tick;
1231\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1368\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1232\& ev_periodic_start (loop, &hourly_tick); 1369\& ev_periodic_start (loop, &hourly_tick);
1233.Ve 1370.Ve
1234.PP 1371.PP
1235Example: the same as above, but use a reschedule callback to do it: 1372Example: The same as above, but use a reschedule callback to do it:
1236.PP 1373.PP
1237.Vb 1 1374.Vb 1
1238\& #include <math.h> 1375\& #include <math.h>
1239.Ve 1376.Ve
1240.PP 1377.PP
… …
1248.PP 1385.PP
1249.Vb 1 1386.Vb 1
1250\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1387\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1251.Ve 1388.Ve
1252.PP 1389.PP
1253Example: call a callback every hour, starting now: 1390Example: Call a callback every hour, starting now:
1254.PP 1391.PP
1255.Vb 4 1392.Vb 4
1256\& struct ev_periodic hourly_tick; 1393\& struct ev_periodic hourly_tick;
1257\& ev_periodic_init (&hourly_tick, clock_cb, 1394\& ev_periodic_init (&hourly_tick, clock_cb,
1258\& fmod (ev_now (loop), 3600.), 3600., 0); 1395\& fmod (ev_now (loop), 3600.), 3600., 0);
… …
1309.IP "int rstatus [read\-write]" 4 1446.IP "int rstatus [read\-write]" 4
1310.IX Item "int rstatus [read-write]" 1447.IX Item "int rstatus [read-write]"
1311The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems 1448The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1312\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). 1449\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1313.PP 1450.PP
1314Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1451Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1315.PP 1452.PP
1316.Vb 5 1453.Vb 5
1317\& static void 1454\& static void
1318\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1455\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1319\& { 1456\& {
… …
1337not exist\*(R" is a status change like any other. The condition \*(L"path does 1474not exist\*(R" is a status change like any other. The condition \*(L"path does
1338not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1475not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1339otherwise always forced to be at least one) and all the other fields of 1476otherwise always forced to be at least one) and all the other fields of
1340the stat buffer having unspecified contents. 1477the stat buffer having unspecified contents.
1341.PP 1478.PP
1479The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1480relative and your working directory changes, the behaviour is undefined.
1481.PP
1342Since there is no standard to do this, the portable implementation simply 1482Since there is no standard to do this, the portable implementation simply
1343calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1483calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1344can specify a recommended polling interval for this case. If you specify 1484can specify a recommended polling interval for this case. If you specify
1345a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1485a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1346unspecified default\fR value will be used (which you can expect to be around 1486unspecified default\fR value will be used (which you can expect to be around
1347five seconds, although this might change dynamically). Libev will also 1487five seconds, although this might change dynamically). Libev will also
1348impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1488impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1350.PP 1490.PP
1351This watcher type is not meant for massive numbers of stat watchers, 1491This watcher type is not meant for massive numbers of stat watchers,
1352as even with OS-supported change notifications, this can be 1492as even with OS-supported change notifications, this can be
1353resource\-intensive. 1493resource\-intensive.
1354.PP 1494.PP
1355At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1495At the time of this writing, only the Linux inotify interface is
1356if demand increases, at least a kqueue and inotify backend will be added. 1496implemented (implementing kqueue support is left as an exercise for the
1497reader). Inotify will be used to give hints only and should not change the
1498semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1499to fall back to regular polling again even with inotify, but changes are
1500usually detected immediately, and if the file exists there will be no
1501polling.
1357.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1502.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1358.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1503.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1359.PD 0 1504.PD 0
1360.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1505.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1361.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1506.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1422\& ev_stat_start (loop, &passwd); 1567\& ev_stat_start (loop, &passwd);
1423.Ve 1568.Ve
1424.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1569.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1425.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1570.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1426.IX Subsection "ev_idle - when you've got nothing better to do..." 1571.IX Subsection "ev_idle - when you've got nothing better to do..."
1427Idle watchers trigger events when there are no other events are pending 1572Idle watchers trigger events when no other events of the same or higher
1428(prepare, check and other idle watchers do not count). That is, as long 1573priority are pending (prepare, check and other idle watchers do not
1429as your process is busy handling sockets or timeouts (or even signals, 1574count).
1430imagine) it will not be triggered. But when your process is idle all idle 1575.PP
1431watchers are being called again and again, once per event loop iteration \- 1576That is, as long as your process is busy handling sockets or timeouts
1577(or even signals, imagine) of the same or higher priority it will not be
1578triggered. But when your process is idle (or only lower-priority watchers
1579are pending), the idle watchers are being called once per event loop
1432until stopped, that is, or your process receives more events and becomes 1580iteration \- until stopped, that is, or your process receives more events
1433busy. 1581and becomes busy again with higher priority stuff.
1434.PP 1582.PP
1435The most noteworthy effect is that as long as any idle watchers are 1583The most noteworthy effect is that as long as any idle watchers are
1436active, the process will not block when waiting for new events. 1584active, the process will not block when waiting for new events.
1437.PP 1585.PP
1438Apart from keeping your process non-blocking (which is a useful 1586Apart from keeping your process non-blocking (which is a useful
… …
1443.IX Item "ev_idle_init (ev_signal *, callback)" 1591.IX Item "ev_idle_init (ev_signal *, callback)"
1444Initialises and configures the idle watcher \- it has no parameters of any 1592Initialises and configures the idle watcher \- it has no parameters of any
1445kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1593kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1446believe me. 1594believe me.
1447.PP 1595.PP
1448Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1596Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1449callback, free it. Alos, use no error checking, as usual. 1597callback, free it. Also, use no error checking, as usual.
1450.PP 1598.PP
1451.Vb 7 1599.Vb 7
1452\& static void 1600\& static void
1453\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1601\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1454\& { 1602\& {
… …
1501are ready to run (it's actually more complicated: it only runs coroutines 1649are ready to run (it's actually more complicated: it only runs coroutines
1502with priority higher than or equal to the event loop and one coroutine 1650with priority higher than or equal to the event loop and one coroutine
1503of lower priority, but only once, using idle watchers to keep the event 1651of lower priority, but only once, using idle watchers to keep the event
1504loop from blocking if lower-priority coroutines are active, thus mapping 1652loop from blocking if lower-priority coroutines are active, thus mapping
1505low-priority coroutines to idle/background tasks). 1653low-priority coroutines to idle/background tasks).
1654.PP
1655It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1656priority, to ensure that they are being run before any other watchers
1657after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1658too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1659supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1660their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1661loops those other event loops might be in an unusable state until their
1662\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1663others).
1506.IP "ev_prepare_init (ev_prepare *, callback)" 4 1664.IP "ev_prepare_init (ev_prepare *, callback)" 4
1507.IX Item "ev_prepare_init (ev_prepare *, callback)" 1665.IX Item "ev_prepare_init (ev_prepare *, callback)"
1508.PD 0 1666.PD 0
1509.IP "ev_check_init (ev_check *, callback)" 4 1667.IP "ev_check_init (ev_check *, callback)" 4
1510.IX Item "ev_check_init (ev_check *, callback)" 1668.IX Item "ev_check_init (ev_check *, callback)"
1511.PD 1669.PD
1512Initialises and configures the prepare or check watcher \- they have no 1670Initialises and configures the prepare or check watcher \- they have no
1513parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1671parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1514macros, but using them is utterly, utterly and completely pointless. 1672macros, but using them is utterly, utterly and completely pointless.
1515.PP 1673.PP
1516Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1674There are a number of principal ways to embed other event loops or modules
1517and a timeout watcher in a prepare handler, as required by libadns, and 1675into libev. Here are some ideas on how to include libadns into libev
1676(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1677use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1678embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1679into the Glib event loop).
1680.PP
1681Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1518in a check watcher, destroy them and call into libadns. What follows is 1682and in a check watcher, destroy them and call into libadns. What follows
1519pseudo-code only of course: 1683is pseudo-code only of course. This requires you to either use a low
1684priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1685the callbacks for the IO/timeout watchers might not have been called yet.
1520.PP 1686.PP
1521.Vb 2 1687.Vb 2
1522\& static ev_io iow [nfd]; 1688\& static ev_io iow [nfd];
1523\& static ev_timer tw; 1689\& static ev_timer tw;
1524.Ve 1690.Ve
1525.PP 1691.PP
1526.Vb 9 1692.Vb 4
1527\& static void 1693\& static void
1528\& io_cb (ev_loop *loop, ev_io *w, int revents) 1694\& io_cb (ev_loop *loop, ev_io *w, int revents)
1529\& { 1695\& {
1530\& // set the relevant poll flags
1531\& // could also call adns_processreadable etc. here
1532\& struct pollfd *fd = (struct pollfd *)w->data;
1533\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1534\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1535\& } 1696\& }
1536.Ve 1697.Ve
1537.PP 1698.PP
1538.Vb 7 1699.Vb 8
1539\& // create io watchers for each fd and a timer before blocking 1700\& // create io watchers for each fd and a timer before blocking
1540\& static void 1701\& static void
1541\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1702\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1542\& { 1703\& {
1543\& int timeout = 3600000;truct pollfd fds [nfd]; 1704\& int timeout = 3600000;
1705\& struct pollfd fds [nfd];
1544\& // actual code will need to loop here and realloc etc. 1706\& // actual code will need to loop here and realloc etc.
1545\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1707\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1546.Ve 1708.Ve
1547.PP 1709.PP
1548.Vb 3 1710.Vb 3
… …
1550\& ev_timer_init (&tw, 0, timeout * 1e-3); 1712\& ev_timer_init (&tw, 0, timeout * 1e-3);
1551\& ev_timer_start (loop, &tw); 1713\& ev_timer_start (loop, &tw);
1552.Ve 1714.Ve
1553.PP 1715.PP
1554.Vb 6 1716.Vb 6
1555\& // create on ev_io per pollfd 1717\& // create one ev_io per pollfd
1556\& for (int i = 0; i < nfd; ++i) 1718\& for (int i = 0; i < nfd; ++i)
1557\& { 1719\& {
1558\& ev_io_init (iow + i, io_cb, fds [i].fd, 1720\& ev_io_init (iow + i, io_cb, fds [i].fd,
1559\& ((fds [i].events & POLLIN ? EV_READ : 0) 1721\& ((fds [i].events & POLLIN ? EV_READ : 0)
1560\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1722\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1561.Ve 1723.Ve
1562.PP 1724.PP
1563.Vb 5 1725.Vb 4
1564\& fds [i].revents = 0; 1726\& fds [i].revents = 0;
1565\& iow [i].data = fds + i;
1566\& ev_io_start (loop, iow + i); 1727\& ev_io_start (loop, iow + i);
1567\& } 1728\& }
1568\& } 1729\& }
1569.Ve 1730.Ve
1570.PP 1731.PP
… …
1574\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1735\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1575\& { 1736\& {
1576\& ev_timer_stop (loop, &tw); 1737\& ev_timer_stop (loop, &tw);
1577.Ve 1738.Ve
1578.PP 1739.PP
1579.Vb 2 1740.Vb 8
1580\& for (int i = 0; i < nfd; ++i) 1741\& for (int i = 0; i < nfd; ++i)
1742\& {
1743\& // set the relevant poll flags
1744\& // could also call adns_processreadable etc. here
1745\& struct pollfd *fd = fds + i;
1746\& int revents = ev_clear_pending (iow + i);
1747\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1748\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1749.Ve
1750.PP
1751.Vb 3
1752\& // now stop the watcher
1581\& ev_io_stop (loop, iow + i); 1753\& ev_io_stop (loop, iow + i);
1754\& }
1582.Ve 1755.Ve
1583.PP 1756.PP
1584.Vb 2 1757.Vb 2
1585\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1758\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1759\& }
1760.Ve
1761.PP
1762Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1763in the prepare watcher and would dispose of the check watcher.
1764.PP
1765Method 3: If the module to be embedded supports explicit event
1766notification (adns does), you can also make use of the actual watcher
1767callbacks, and only destroy/create the watchers in the prepare watcher.
1768.PP
1769.Vb 5
1770\& static void
1771\& timer_cb (EV_P_ ev_timer *w, int revents)
1772\& {
1773\& adns_state ads = (adns_state)w->data;
1774\& update_now (EV_A);
1775.Ve
1776.PP
1777.Vb 2
1778\& adns_processtimeouts (ads, &tv_now);
1779\& }
1780.Ve
1781.PP
1782.Vb 5
1783\& static void
1784\& io_cb (EV_P_ ev_io *w, int revents)
1785\& {
1786\& adns_state ads = (adns_state)w->data;
1787\& update_now (EV_A);
1788.Ve
1789.PP
1790.Vb 3
1791\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1792\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1793\& }
1794.Ve
1795.PP
1796.Vb 1
1797\& // do not ever call adns_afterpoll
1798.Ve
1799.PP
1800Method 4: Do not use a prepare or check watcher because the module you
1801want to embed is too inflexible to support it. Instead, youc na override
1802their poll function. The drawback with this solution is that the main
1803loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1804this.
1805.PP
1806.Vb 4
1807\& static gint
1808\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1809\& {
1810\& int got_events = 0;
1811.Ve
1812.PP
1813.Vb 2
1814\& for (n = 0; n < nfds; ++n)
1815\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1816.Ve
1817.PP
1818.Vb 2
1819\& if (timeout >= 0)
1820\& // create/start timer
1821.Ve
1822.PP
1823.Vb 2
1824\& // poll
1825\& ev_loop (EV_A_ 0);
1826.Ve
1827.PP
1828.Vb 3
1829\& // stop timer again
1830\& if (timeout >= 0)
1831\& ev_timer_stop (EV_A_ &to);
1832.Ve
1833.PP
1834.Vb 3
1835\& // stop io watchers again - their callbacks should have set
1836\& for (n = 0; n < nfds; ++n)
1837\& ev_io_stop (EV_A_ iow [n]);
1838.Ve
1839.PP
1840.Vb 2
1841\& return got_events;
1586\& } 1842\& }
1587.Ve 1843.Ve
1588.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1844.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1589.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1845.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1590.IX Subsection "ev_embed - when one backend isn't enough..." 1846.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1774.PP 2030.PP
1775.Vb 1 2031.Vb 1
1776\& #include <ev++.h> 2032\& #include <ev++.h>
1777.Ve 2033.Ve
1778.PP 2034.PP
1779(it is not installed by default). This automatically includes \fIev.h\fR 2035This automatically includes \fIev.h\fR and puts all of its definitions (many
1780and puts all of its definitions (many of them macros) into the global 2036of them macros) into the global namespace. All \*(C+ specific things are
1781namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2037put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2038options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1782.PP 2039.PP
1783It should support all the same embedding options as \fIev.h\fR, most notably 2040Care has been taken to keep the overhead low. The only data member the \*(C+
1784\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2041classes add (compared to plain C\-style watchers) is the event loop pointer
2042that the watcher is associated with (or no additional members at all if
2043you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2044.PP
2045Currently, functions, and static and non-static member functions can be
2046used as callbacks. Other types should be easy to add as long as they only
2047need one additional pointer for context. If you need support for other
2048types of functors please contact the author (preferably after implementing
2049it).
1785.PP 2050.PP
1786Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2051Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1787.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2052.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1788.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2053.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1789.IX Item "ev::READ, ev::WRITE etc." 2054.IX Item "ev::READ, ev::WRITE etc."
… …
1801which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2066which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1802defines by many implementations. 2067defines by many implementations.
1803.Sp 2068.Sp
1804All of those classes have these methods: 2069All of those classes have these methods:
1805.RS 4 2070.RS 4
1806.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2071.IP "ev::TYPE::TYPE ()" 4
1807.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2072.IX Item "ev::TYPE::TYPE ()"
1808.PD 0 2073.PD 0
1809.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2074.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1810.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2075.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1811.IP "ev::TYPE::~TYPE" 4 2076.IP "ev::TYPE::~TYPE" 4
1812.IX Item "ev::TYPE::~TYPE" 2077.IX Item "ev::TYPE::~TYPE"
1813.PD 2078.PD
1814The constructor takes a pointer to an object and a method pointer to 2079The constructor (optionally) takes an event loop to associate the watcher
1815the event handler callback to call in this class. The constructor calls 2080with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1816\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2081.Sp
1817before starting it. If you do not specify a loop then the constructor 2082The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1818automatically associates the default loop with this watcher. 2083\&\f(CW\*(C`set\*(C'\fR method before starting it.
2084.Sp
2085It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2086method to set a callback before you can start the watcher.
2087.Sp
2088(The reason why you have to use a method is a limitation in \*(C+ which does
2089not allow explicit template arguments for constructors).
1819.Sp 2090.Sp
1820The destructor automatically stops the watcher if it is active. 2091The destructor automatically stops the watcher if it is active.
2092.IP "w\->set<class, &class::method> (object *)" 4
2093.IX Item "w->set<class, &class::method> (object *)"
2094This method sets the callback method to call. The method has to have a
2095signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2096first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2097parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2098.Sp
2099This method synthesizes efficient thunking code to call your method from
2100the C callback that libev requires. If your compiler can inline your
2101callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2102your compiler is good :), then the method will be fully inlined into the
2103thunking function, making it as fast as a direct C callback.
2104.Sp
2105Example: simple class declaration and watcher initialisation
2106.Sp
2107.Vb 4
2108\& struct myclass
2109\& {
2110\& void io_cb (ev::io &w, int revents) { }
2111\& }
2112.Ve
2113.Sp
2114.Vb 3
2115\& myclass obj;
2116\& ev::io iow;
2117\& iow.set <myclass, &myclass::io_cb> (&obj);
2118.Ve
2119.IP "w\->set<function> (void *data = 0)" 4
2120.IX Item "w->set<function> (void *data = 0)"
2121Also sets a callback, but uses a static method or plain function as
2122callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2123\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2124.Sp
2125The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2126.Sp
2127See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2128.Sp
2129Example:
2130.Sp
2131.Vb 2
2132\& static void io_cb (ev::io &w, int revents) { }
2133\& iow.set <io_cb> ();
2134.Ve
1821.IP "w\->set (struct ev_loop *)" 4 2135.IP "w\->set (struct ev_loop *)" 4
1822.IX Item "w->set (struct ev_loop *)" 2136.IX Item "w->set (struct ev_loop *)"
1823Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2137Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1824do this when the watcher is inactive (and not pending either). 2138do this when the watcher is inactive (and not pending either).
1825.IP "w\->set ([args])" 4 2139.IP "w\->set ([args])" 4
1826.IX Item "w->set ([args])" 2140.IX Item "w->set ([args])"
1827Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2141Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1828called at least once. Unlike the C counterpart, an active watcher gets 2142called at least once. Unlike the C counterpart, an active watcher gets
1829automatically stopped and restarted. 2143automatically stopped and restarted when reconfiguring it with this
2144method.
1830.IP "w\->start ()" 4 2145.IP "w\->start ()" 4
1831.IX Item "w->start ()" 2146.IX Item "w->start ()"
1832Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2147Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1833constructor already takes the loop. 2148constructor already stores the event loop.
1834.IP "w\->stop ()" 4 2149.IP "w\->stop ()" 4
1835.IX Item "w->stop ()" 2150.IX Item "w->stop ()"
1836Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2151Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1837.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2152.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1838.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2153.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1864.Vb 2 2179.Vb 2
1865\& myclass (); 2180\& myclass ();
1866\& } 2181\& }
1867.Ve 2182.Ve
1868.PP 2183.PP
1869.Vb 6 2184.Vb 4
1870\& myclass::myclass (int fd) 2185\& myclass::myclass (int fd)
1871\& : io (this, &myclass::io_cb),
1872\& idle (this, &myclass::idle_cb)
1873\& { 2186\& {
2187\& io .set <myclass, &myclass::io_cb > (this);
2188\& idle.set <myclass, &myclass::idle_cb> (this);
2189.Ve
2190.PP
2191.Vb 2
1874\& io.start (fd, ev::READ); 2192\& io.start (fd, ev::READ);
1875\& } 2193\& }
1876.Ve 2194.Ve
1877.SH "MACRO MAGIC" 2195.SH "MACRO MAGIC"
1878.IX Header "MACRO MAGIC" 2196.IX Header "MACRO MAGIC"
1879Libev can be compiled with a variety of options, the most fundemantal is 2197Libev can be compiled with a variety of options, the most fundemantal is
1880\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2198\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
1881callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2199callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1882.PP 2200.PP
1883To make it easier to write programs that cope with either variant, the 2201To make it easier to write programs that cope with either variant, the
1884following macros are defined: 2202following macros are defined:
1885.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2203.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
1920.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2238.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1921.IX Item "EV_DEFAULT, EV_DEFAULT_" 2239.IX Item "EV_DEFAULT, EV_DEFAULT_"
1922Similar to the other two macros, this gives you the value of the default 2240Similar to the other two macros, this gives you the value of the default
1923loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2241loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1924.PP 2242.PP
1925Example: Declare and initialise a check watcher, working regardless of 2243Example: Declare and initialise a check watcher, utilising the above
1926wether multiple loops are supported or not. 2244macros so it will work regardless of whether multiple loops are supported
2245or not.
1927.PP 2246.PP
1928.Vb 5 2247.Vb 5
1929\& static void 2248\& static void
1930\& check_cb (EV_P_ ev_timer *w, int revents) 2249\& check_cb (EV_P_ ev_timer *w, int revents)
1931\& { 2250\& {
… …
1994.Vb 1 2313.Vb 1
1995\& ev_win32.c required on win32 platforms only 2314\& ev_win32.c required on win32 platforms only
1996.Ve 2315.Ve
1997.PP 2316.PP
1998.Vb 5 2317.Vb 5
1999\& ev_select.c only when select backend is enabled (which is by default) 2318\& ev_select.c only when select backend is enabled (which is enabled by default)
2000\& ev_poll.c only when poll backend is enabled (disabled by default) 2319\& ev_poll.c only when poll backend is enabled (disabled by default)
2001\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2320\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2002\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2321\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2003\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2322\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2004.Ve 2323.Ve
… …
2125otherwise another method will be used as fallback. This is the preferred 2444otherwise another method will be used as fallback. This is the preferred
2126backend for Solaris 10 systems. 2445backend for Solaris 10 systems.
2127.IP "\s-1EV_USE_DEVPOLL\s0" 4 2446.IP "\s-1EV_USE_DEVPOLL\s0" 4
2128.IX Item "EV_USE_DEVPOLL" 2447.IX Item "EV_USE_DEVPOLL"
2129reserved for future expansion, works like the \s-1USE\s0 symbols above. 2448reserved for future expansion, works like the \s-1USE\s0 symbols above.
2449.IP "\s-1EV_USE_INOTIFY\s0" 4
2450.IX Item "EV_USE_INOTIFY"
2451If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2452interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2453be detected at runtime.
2130.IP "\s-1EV_H\s0" 4 2454.IP "\s-1EV_H\s0" 4
2131.IX Item "EV_H" 2455.IX Item "EV_H"
2132The name of the \fIev.h\fR header file used to include it. The default if 2456The name of the \fIev.h\fR header file used to include it. The default if
2133undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2457undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2134can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2458can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2152If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2476If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2153will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2477will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2154additional independent event loops. Otherwise there will be no support 2478additional independent event loops. Otherwise there will be no support
2155for multiple event loops and there is no first event loop pointer 2479for multiple event loops and there is no first event loop pointer
2156argument. Instead, all functions act on the single default loop. 2480argument. Instead, all functions act on the single default loop.
2481.IP "\s-1EV_MINPRI\s0" 4
2482.IX Item "EV_MINPRI"
2483.PD 0
2484.IP "\s-1EV_MAXPRI\s0" 4
2485.IX Item "EV_MAXPRI"
2486.PD
2487The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2488\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2489provide for more priorities by overriding those symbols (usually defined
2490to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2491.Sp
2492When doing priority-based operations, libev usually has to linearly search
2493all the priorities, so having many of them (hundreds) uses a lot of space
2494and time, so using the defaults of five priorities (\-2 .. +2) is usually
2495fine.
2496.Sp
2497If your embedding app does not need any priorities, defining these both to
2498\&\f(CW0\fR will save some memory and cpu.
2157.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2499.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2158.IX Item "EV_PERIODIC_ENABLE" 2500.IX Item "EV_PERIODIC_ENABLE"
2159If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2501If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2502defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2503code.
2504.IP "\s-1EV_IDLE_ENABLE\s0" 4
2505.IX Item "EV_IDLE_ENABLE"
2506If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2160defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2507defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2161code. 2508code.
2162.IP "\s-1EV_EMBED_ENABLE\s0" 4 2509.IP "\s-1EV_EMBED_ENABLE\s0" 4
2163.IX Item "EV_EMBED_ENABLE" 2510.IX Item "EV_EMBED_ENABLE"
2164If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2511If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2179.IP "\s-1EV_PID_HASHSIZE\s0" 4 2526.IP "\s-1EV_PID_HASHSIZE\s0" 4
2180.IX Item "EV_PID_HASHSIZE" 2527.IX Item "EV_PID_HASHSIZE"
2181\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2528\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2182pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 2529pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2183than enough. If you need to manage thousands of children you might want to 2530than enough. If you need to manage thousands of children you might want to
2184increase this value. 2531increase this value (\fImust\fR be a power of two).
2532.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2533.IX Item "EV_INOTIFY_HASHSIZE"
2534\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2535inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2536usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2537watchers you might want to increase this value (\fImust\fR be a power of
2538two).
2185.IP "\s-1EV_COMMON\s0" 4 2539.IP "\s-1EV_COMMON\s0" 4
2186.IX Item "EV_COMMON" 2540.IX Item "EV_COMMON"
2187By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2541By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2188this macro to a something else you can include more and other types of 2542this macro to a something else you can include more and other types of
2189members. You have to define it each time you include one of the files, 2543members. You have to define it each time you include one of the files,
… …
2219interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2573interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2220will be compiled. It is pretty complex because it provides its own header 2574will be compiled. It is pretty complex because it provides its own header
2221file. 2575file.
2222.Sp 2576.Sp
2223The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2577The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2224that everybody includes and which overrides some autoconf choices: 2578that everybody includes and which overrides some configure choices:
2225.Sp 2579.Sp
2226.Vb 4 2580.Vb 9
2581\& #define EV_MINIMAL 1
2227\& #define EV_USE_POLL 0 2582\& #define EV_USE_POLL 0
2228\& #define EV_MULTIPLICITY 0 2583\& #define EV_MULTIPLICITY 0
2229\& #define EV_PERIODICS 0 2584\& #define EV_PERIODIC_ENABLE 0
2585\& #define EV_STAT_ENABLE 0
2586\& #define EV_FORK_ENABLE 0
2230\& #define EV_CONFIG_H <config.h> 2587\& #define EV_CONFIG_H <config.h>
2588\& #define EV_MINPRI 0
2589\& #define EV_MAXPRI 0
2231.Ve 2590.Ve
2232.Sp 2591.Sp
2233.Vb 1 2592.Vb 1
2234\& #include "ev++.h" 2593\& #include "ev++.h"
2235.Ve 2594.Ve
… …
2243.SH "COMPLEXITIES" 2602.SH "COMPLEXITIES"
2244.IX Header "COMPLEXITIES" 2603.IX Header "COMPLEXITIES"
2245In this section the complexities of (many of) the algorithms used inside 2604In this section the complexities of (many of) the algorithms used inside
2246libev will be explained. For complexity discussions about backends see the 2605libev will be explained. For complexity discussions about backends see the
2247documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2606documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2607.Sp
2608All of the following are about amortised time: If an array needs to be
2609extended, libev needs to realloc and move the whole array, but this
2610happens asymptotically never with higher number of elements, so O(1) might
2611mean it might do a lengthy realloc operation in rare cases, but on average
2612it is much faster and asymptotically approaches constant time.
2248.RS 4 2613.RS 4
2249.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2614.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2250.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2615.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2251.PD 0 2616This means that, when you have a watcher that triggers in one hour and
2617there are 100 watchers that would trigger before that then inserting will
2618have to skip those 100 watchers.
2252.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2619.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2253.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2620.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2621That means that for changing a timer costs less than removing/adding them
2622as only the relative motion in the event queue has to be paid for.
2254.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2623.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2255.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2624.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2256.IP "Stopping check/prepare/idle watchers: O(1)" 4 2625These just add the watcher into an array or at the head of a list.
2257.IX Item "Stopping check/prepare/idle watchers: O(1)" 2626=item Stopping check/prepare/idle watchers: O(1)
2258.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2627.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2259.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2628.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2629These watchers are stored in lists then need to be walked to find the
2630correct watcher to remove. The lists are usually short (you don't usually
2631have many watchers waiting for the same fd or signal).
2260.IP "Finding the next timer per loop iteration: O(1)" 4 2632.IP "Finding the next timer per loop iteration: O(1)" 4
2261.IX Item "Finding the next timer per loop iteration: O(1)" 2633.IX Item "Finding the next timer per loop iteration: O(1)"
2634.PD 0
2262.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2635.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2263.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2636.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2637.PD
2638A change means an I/O watcher gets started or stopped, which requires
2639libev to recalculate its status (and possibly tell the kernel).
2264.IP "Activating one watcher: O(1)" 4 2640.IP "Activating one watcher: O(1)" 4
2265.IX Item "Activating one watcher: O(1)" 2641.IX Item "Activating one watcher: O(1)"
2642.PD 0
2643.IP "Priority handling: O(number_of_priorities)" 4
2644.IX Item "Priority handling: O(number_of_priorities)"
2645.PD
2646Priorities are implemented by allocating some space for each
2647priority. When doing priority-based operations, libev usually has to
2648linearly search all the priorities.
2266.RE 2649.RE
2267.RS 4 2650.RS 4
2268.PD
2269.SH "AUTHOR" 2651.SH "AUTHOR"
2270.IX Header "AUTHOR" 2652.IX Header "AUTHOR"
2271Marc Lehmann <libev@schmorp.de>. 2653Marc Lehmann <libev@schmorp.de>.

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