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Revision 1.40 by root, Fri Dec 7 19:23:48 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 "2007-12-07" "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
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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
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257Usually, it's a good idea to terminate if the major versions mismatch, 270Usually, it's a good idea to terminate if the major versions mismatch,
258as this indicates an incompatible change. Minor versions are usually 271as this indicates an incompatible change. Minor versions are usually
259compatible to older versions, so a larger minor version alone is usually 272compatible to older versions, so a larger minor version alone is usually
260not a problem. 273not a problem.
261.Sp 274.Sp
262Example: make sure we haven't accidentally been linked against the wrong 275Example: Make sure we haven't accidentally been linked against the wrong
263version: 276version.
264.Sp 277.Sp
265.Vb 3 278.Vb 3
266\& assert (("libev version mismatch", 279\& assert (("libev version mismatch",
267\& ev_version_major () == EV_VERSION_MAJOR 280\& ev_version_major () == EV_VERSION_MAJOR
268\& && ev_version_minor () >= EV_VERSION_MINOR)); 281\& && ev_version_minor () >= EV_VERSION_MINOR));
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296might be supported on the current system, you would need to look at 309might 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 310\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
298recommended ones. 311recommended ones.
299.Sp 312.Sp
300See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 313See 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))" 4 314.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
302.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 315.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
303Sets the allocation function to use (the prototype and semantics are 316Sets the allocation function to use (the prototype is similar \- the
304identical to the realloc C function). It is used to allocate and free 317semantics is identical \- to the realloc C function). It is used to
305memory (no surprises here). If it returns zero when memory needs to be 318allocate and free memory (no surprises here). If it returns zero when
306allocated, the library might abort or take some potentially destructive 319memory needs to be allocated, the library might abort or take some
307action. The default is your system realloc function. 320potentially destructive action. The default is your system realloc
321function.
308.Sp 322.Sp
309You could override this function in high-availability programs to, say, 323You could override this function in high-availability programs to, say,
310free some memory if it cannot allocate memory, to use a special allocator, 324free 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. 325or even to sleep a while and retry until some memory is available.
312.Sp 326.Sp
313Example: replace the libev allocator with one that waits a bit and then 327Example: Replace the libev allocator with one that waits a bit and then
314retries: better than mine). 328retries).
315.Sp 329.Sp
316.Vb 6 330.Vb 6
317\& static void * 331\& static void *
318\& persistent_realloc (void *ptr, size_t size) 332\& persistent_realloc (void *ptr, size_t size)
319\& { 333\& {
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345callback is set, then libev will expect it to remedy the sitution, no 359callback is set, then libev will expect it to remedy the sitution, no
346matter what, when it returns. That is, libev will generally retry the 360matter what, when it returns. That is, libev will generally retry the
347requested operation, or, if the condition doesn't go away, do bad stuff 361requested operation, or, if the condition doesn't go away, do bad stuff
348(such as abort). 362(such as abort).
349.Sp 363.Sp
350Example: do the same thing as libev does internally: 364Example: This is basically the same thing that libev does internally, too.
351.Sp 365.Sp
352.Vb 6 366.Vb 6
353\& static void 367\& static void
354\& fatal_error (const char *msg) 368\& fatal_error (const char *msg)
355\& { 369\& {
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401or setgid) then libev will \fInot\fR look at the environment variable 415or 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 416\&\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 417override 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 418useful to try out specific backends to test their performance, or to work
405around bugs. 419around bugs.
420.ie n .IP """EVFLAG_FORKCHECK""" 4
421.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
422.IX Item "EVFLAG_FORKCHECK"
423Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
424a fork, you can also make libev check for a fork in each iteration by
425enabling this flag.
426.Sp
427This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
428and thus this might slow down your event loop if you do a lot of loop
429iterations and little real work, but is usually not noticeable (on my
430Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
431without a syscall and thus \fIvery\fR fast, but my Linux system also has
432\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
433.Sp
434The big advantage of this flag is that you can forget about fork (and
435forget about forgetting to tell libev about forking) when you use this
436flag.
437.Sp
438This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
439environment variable.
406.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 440.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
407.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 441.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
408.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 442.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
409This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 443This 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, 444libev 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 538Similar 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 539always 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 540handle signal and child watchers, and attempts to do so will be greeted by
507undefined behaviour (or a failed assertion if assertions are enabled). 541undefined behaviour (or a failed assertion if assertions are enabled).
508.Sp 542.Sp
509Example: try to create a event loop that uses epoll and nothing else. 543Example: Try to create a event loop that uses epoll and nothing else.
510.Sp 544.Sp
511.Vb 3 545.Vb 3
512\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 546\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
513\& if (!epoller) 547\& if (!epoller)
514\& fatal ("no epoll found here, maybe it hides under your chair"); 548\& fatal ("no epoll found here, maybe it hides under your chair");
… …
551.IP "ev_loop_fork (loop)" 4 585.IP "ev_loop_fork (loop)" 4
552.IX Item "ev_loop_fork (loop)" 586.IX Item "ev_loop_fork (loop)"
553Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 587Like \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 588\&\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. 589after fork, and how you do this is entirely your own problem.
590.IP "unsigned int ev_loop_count (loop)" 4
591.IX Item "unsigned int ev_loop_count (loop)"
592Returns the count of loop iterations for the loop, which is identical to
593the number of times libev did poll for new events. It starts at \f(CW0\fR and
594happily wraps around with enough iterations.
595.Sp
596This value can sometimes be useful as a generation counter of sorts (it
597\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
598\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
556.IP "unsigned int ev_backend (loop)" 4 599.IP "unsigned int ev_backend (loop)" 4
557.IX Item "unsigned int ev_backend (loop)" 600.IX Item "unsigned int ev_backend (loop)"
558Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 601Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
559use. 602use.
560.IP "ev_tstamp ev_now (loop)" 4 603.IP "ev_tstamp ev_now (loop)" 4
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612\& be handled here by queueing them when their watcher gets executed. 655\& be handled here by queueing them when their watcher gets executed.
613\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 656\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
614\& were used, return, otherwise continue with step *. 657\& were used, return, otherwise continue with step *.
615.Ve 658.Ve
616.Sp 659.Sp
617Example: queue some jobs and then loop until no events are outsanding 660Example: Queue some jobs and then loop until no events are outsanding
618anymore. 661anymore.
619.Sp 662.Sp
620.Vb 4 663.Vb 4
621\& ... queue jobs here, make sure they register event watchers as long 664\& ... 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..) 665\& ... as they still have work to do (even an idle watcher will do..)
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644visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 687visible 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 688no 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 689way 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. 690libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
648.Sp 691.Sp
649Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 692Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
650running when nothing else is active. 693running when nothing else is active.
651.Sp 694.Sp
652.Vb 4 695.Vb 4
653\& struct dv_signal exitsig; 696\& struct ev_signal exitsig;
654\& ev_signal_init (&exitsig, sig_cb, SIGINT); 697\& ev_signal_init (&exitsig, sig_cb, SIGINT);
655\& ev_signal_start (myloop, &exitsig); 698\& ev_signal_start (loop, &exitsig);
656\& evf_unref (myloop); 699\& evf_unref (loop);
657.Ve 700.Ve
658.Sp 701.Sp
659Example: for some weird reason, unregister the above signal handler again. 702Example: For some weird reason, unregister the above signal handler again.
660.Sp 703.Sp
661.Vb 2 704.Vb 2
662\& ev_ref (myloop); 705\& ev_ref (loop);
663\& ev_signal_stop (myloop, &exitsig); 706\& ev_signal_stop (loop, &exitsig);
664.Ve 707.Ve
665.SH "ANATOMY OF A WATCHER" 708.SH "ANATOMY OF A WATCHER"
666.IX Header "ANATOMY OF A WATCHER" 709.IX Header "ANATOMY OF A WATCHER"
667A watcher is a structure that you create and register to record your 710A 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 711interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
848Returns a true value iff the watcher is pending, (i.e. it has outstanding 891Returns 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 892events 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 893is 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 894\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
852libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 895libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
853.IP "callback = ev_cb (ev_TYPE *watcher)" 4 896.IP "callback ev_cb (ev_TYPE *watcher)" 4
854.IX Item "callback = ev_cb (ev_TYPE *watcher)" 897.IX Item "callback ev_cb (ev_TYPE *watcher)"
855Returns the callback currently set on the watcher. 898Returns the callback currently set on the watcher.
856.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 899.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
857.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 900.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
858Change the callback. You can change the callback at virtually any time 901Change the callback. You can change the callback at virtually any time
859(modulo threads). 902(modulo threads).
903.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
904.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
905.PD 0
906.IP "int ev_priority (ev_TYPE *watcher)" 4
907.IX Item "int ev_priority (ev_TYPE *watcher)"
908.PD
909Set and query the priority of the watcher. The priority is a small
910integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
911(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
912before watchers with lower priority, but priority will not keep watchers
913from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
914.Sp
915This means that priorities are \fIonly\fR used for ordering callback
916invocation after new events have been received. This is useful, for
917example, to reduce latency after idling, or more often, to bind two
918watchers on the same event and make sure one is called first.
919.Sp
920If you need to suppress invocation when higher priority events are pending
921you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
922.Sp
923The default priority used by watchers when no priority has been set is
924always \f(CW0\fR, which is supposed to not be too high and not be too low :).
925.Sp
926Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
927fine, as long as you do not mind that the priority value you query might
928or might not have been adjusted to be within valid range.
860.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 929.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" 930.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 931Each 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 932and 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 933to associate arbitrary data with your watcher. If you need more data and
… …
885\& struct my_io *w = (struct my_io *)w_; 954\& struct my_io *w = (struct my_io *)w_;
886\& ... 955\& ...
887\& } 956\& }
888.Ve 957.Ve
889.PP 958.PP
890More interesting and less C\-conformant ways of catsing your callback type 959More interesting and less C\-conformant ways of casting your callback type
891have been omitted.... 960instead have been omitted.
961.PP
962Another common scenario is having some data structure with multiple
963watchers:
964.PP
965.Vb 6
966\& struct my_biggy
967\& {
968\& int some_data;
969\& ev_timer t1;
970\& ev_timer t2;
971\& }
972.Ve
973.PP
974In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
975you need to use \f(CW\*(C`offsetof\*(C'\fR:
976.PP
977.Vb 1
978\& #include <stddef.h>
979.Ve
980.PP
981.Vb 6
982\& static void
983\& t1_cb (EV_P_ struct ev_timer *w, int revents)
984\& {
985\& struct my_biggy big = (struct my_biggy *
986\& (((char *)w) - offsetof (struct my_biggy, t1));
987\& }
988.Ve
989.PP
990.Vb 6
991\& static void
992\& t2_cb (EV_P_ struct ev_timer *w, int revents)
993\& {
994\& struct my_biggy big = (struct my_biggy *
995\& (((char *)w) - offsetof (struct my_biggy, t2));
996\& }
997.Ve
892.SH "WATCHER TYPES" 998.SH "WATCHER TYPES"
893.IX Header "WATCHER TYPES" 999.IX Header "WATCHER TYPES"
894This section describes each watcher in detail, but will not repeat 1000This section describes each watcher in detail, but will not repeat
895information given in the last section. Any initialisation/set macros, 1001information given in the last section. Any initialisation/set macros,
896functions and members specific to the watcher type are explained. 1002functions 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 1044it 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. 1045\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
940.PP 1046.PP
941If you cannot run the fd in non-blocking mode (for example you should not 1047If 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 1048play 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 1049whether 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 1050such as poll (fortunately in our Xlib example, Xlib already does this on
945its own, so its quite safe to use). 1051its own, so its quite safe to use).
946.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1052.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)" 1053.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
948.PD 0 1054.PD 0
… …
957The file descriptor being watched. 1063The file descriptor being watched.
958.IP "int events [read\-only]" 4 1064.IP "int events [read\-only]" 4
959.IX Item "int events [read-only]" 1065.IX Item "int events [read-only]"
960The events being watched. 1066The events being watched.
961.PP 1067.PP
962Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1068Example: 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 1069readable, but only once. Since it is likely line\-buffered, you could
964attempt to read a whole line in the callback: 1070attempt to read a whole line in the callback.
965.PP 1071.PP
966.Vb 6 1072.Vb 6
967\& static void 1073\& static void
968\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1074\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
969\& { 1075\& {
… …
1024.IP "ev_timer_again (loop)" 4 1130.IP "ev_timer_again (loop)" 4
1025.IX Item "ev_timer_again (loop)" 1131.IX Item "ev_timer_again (loop)"
1026This will act as if the timer timed out and restart it again if it is 1132This will act as if the timer timed out and restart it again if it is
1027repeating. The exact semantics are: 1133repeating. The exact semantics are:
1028.Sp 1134.Sp
1135If the timer is pending, its pending status is cleared.
1136.Sp
1029If the timer is started but nonrepeating, stop it. 1137If the timer is started but nonrepeating, stop it (as if it timed out).
1030.Sp 1138.Sp
1031If the timer is repeating, either start it if necessary (with the repeat 1139If the timer is repeating, either start it if necessary (with the
1032value), or reset the running timer to the repeat value. 1140\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1033.Sp 1141.Sp
1034This sounds a bit complicated, but here is a useful and typical 1142This sounds a bit complicated, but here is a useful and typical
1035example: Imagine you have a tcp connection and you want a so-called 1143example: 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, 1144timeout, 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 1145seconds 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 1146configure 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 1147\&\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 1148you 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 1149socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1042need be. 1150automatically restart it if need be.
1043.Sp 1151.Sp
1044You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1152That 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: 1153altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1046.Sp 1154.Sp
1047.Vb 8 1155.Vb 8
1048\& ev_timer_init (timer, callback, 0., 5.); 1156\& ev_timer_init (timer, callback, 0., 5.);
1049\& ev_timer_again (loop, timer); 1157\& ev_timer_again (loop, timer);
1050\& ... 1158\& ...
… …
1053\& ... 1161\& ...
1054\& timer->again = 10.; 1162\& timer->again = 10.;
1055\& ev_timer_again (loop, timer); 1163\& ev_timer_again (loop, timer);
1056.Ve 1164.Ve
1057.Sp 1165.Sp
1058This is more efficient then stopping/starting the timer eahc time you want 1166This is more slightly efficient then stopping/starting the timer each time
1059to modify its timeout value. 1167you want to modify its timeout value.
1060.IP "ev_tstamp repeat [read\-write]" 4 1168.IP "ev_tstamp repeat [read\-write]" 4
1061.IX Item "ev_tstamp repeat [read-write]" 1169.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 1170The 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), 1171or \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. 1172which is also when any modifications are taken into account.
1065.PP 1173.PP
1066Example: create a timer that fires after 60 seconds. 1174Example: Create a timer that fires after 60 seconds.
1067.PP 1175.PP
1068.Vb 5 1176.Vb 5
1069\& static void 1177\& static void
1070\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1178\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1071\& { 1179\& {
… …
1077\& struct ev_timer mytimer; 1185\& struct ev_timer mytimer;
1078\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1186\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1079\& ev_timer_start (loop, &mytimer); 1187\& ev_timer_start (loop, &mytimer);
1080.Ve 1188.Ve
1081.PP 1189.PP
1082Example: create a timeout timer that times out after 10 seconds of 1190Example: Create a timeout timer that times out after 10 seconds of
1083inactivity. 1191inactivity.
1084.PP 1192.PP
1085.Vb 5 1193.Vb 5
1086\& static void 1194\& static void
1087\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1195\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
1212.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1320.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 1321The current reschedule callback, or \f(CW0\fR, if this functionality is
1214switched off. Can be changed any time, but changes only take effect when 1322switched 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. 1323the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1216.PP 1324.PP
1217Example: call a callback every hour, or, more precisely, whenever the 1325Example: Call a callback every hour, or, more precisely, whenever the
1218system clock is divisible by 3600. The callback invocation times have 1326system clock is divisible by 3600. The callback invocation times have
1219potentially a lot of jittering, but good long-term stability. 1327potentially a lot of jittering, but good long-term stability.
1220.PP 1328.PP
1221.Vb 5 1329.Vb 5
1222\& static void 1330\& static void
… …
1230\& struct ev_periodic hourly_tick; 1338\& struct ev_periodic hourly_tick;
1231\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1339\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1232\& ev_periodic_start (loop, &hourly_tick); 1340\& ev_periodic_start (loop, &hourly_tick);
1233.Ve 1341.Ve
1234.PP 1342.PP
1235Example: the same as above, but use a reschedule callback to do it: 1343Example: The same as above, but use a reschedule callback to do it:
1236.PP 1344.PP
1237.Vb 1 1345.Vb 1
1238\& #include <math.h> 1346\& #include <math.h>
1239.Ve 1347.Ve
1240.PP 1348.PP
… …
1248.PP 1356.PP
1249.Vb 1 1357.Vb 1
1250\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1358\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1251.Ve 1359.Ve
1252.PP 1360.PP
1253Example: call a callback every hour, starting now: 1361Example: Call a callback every hour, starting now:
1254.PP 1362.PP
1255.Vb 4 1363.Vb 4
1256\& struct ev_periodic hourly_tick; 1364\& struct ev_periodic hourly_tick;
1257\& ev_periodic_init (&hourly_tick, clock_cb, 1365\& ev_periodic_init (&hourly_tick, clock_cb,
1258\& fmod (ev_now (loop), 3600.), 3600., 0); 1366\& fmod (ev_now (loop), 3600.), 3600., 0);
… …
1309.IP "int rstatus [read\-write]" 4 1417.IP "int rstatus [read\-write]" 4
1310.IX Item "int rstatus [read-write]" 1418.IX Item "int rstatus [read-write]"
1311The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems 1419The 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). 1420\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1313.PP 1421.PP
1314Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1422Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1315.PP 1423.PP
1316.Vb 5 1424.Vb 5
1317\& static void 1425\& static void
1318\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1426\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1319\& { 1427\& {
… …
1337not exist\*(R" is a status change like any other. The condition \*(L"path does 1445not 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 1446not 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 1447otherwise always forced to be at least one) and all the other fields of
1340the stat buffer having unspecified contents. 1448the stat buffer having unspecified contents.
1341.PP 1449.PP
1450The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1451relative and your working directory changes, the behaviour is undefined.
1452.PP
1342Since there is no standard to do this, the portable implementation simply 1453Since 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 1454calls \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 1455can specify a recommended polling interval for this case. If you specify
1345a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1456a 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 1457unspecified default\fR value will be used (which you can expect to be around
1347five seconds, although this might change dynamically). Libev will also 1458five seconds, although this might change dynamically). Libev will also
1348impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1459impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1350.PP 1461.PP
1351This watcher type is not meant for massive numbers of stat watchers, 1462This watcher type is not meant for massive numbers of stat watchers,
1352as even with OS-supported change notifications, this can be 1463as even with OS-supported change notifications, this can be
1353resource\-intensive. 1464resource\-intensive.
1354.PP 1465.PP
1355At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1466At the time of this writing, only the Linux inotify interface is
1356if demand increases, at least a kqueue and inotify backend will be added. 1467implemented (implementing kqueue support is left as an exercise for the
1468reader). Inotify will be used to give hints only and should not change the
1469semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1470to fall back to regular polling again even with inotify, but changes are
1471usually detected immediately, and if the file exists there will be no
1472polling.
1357.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1473.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)" 1474.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1359.PD 0 1475.PD 0
1360.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1476.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)" 1477.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1422\& ev_stat_start (loop, &passwd); 1538\& ev_stat_start (loop, &passwd);
1423.Ve 1539.Ve
1424.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1540.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..." 1541.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..." 1542.IX Subsection "ev_idle - when you've got nothing better to do..."
1427Idle watchers trigger events when there are no other events are pending 1543Idle 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 1544priority are pending (prepare, check and other idle watchers do not
1429as your process is busy handling sockets or timeouts (or even signals, 1545count).
1430imagine) it will not be triggered. But when your process is idle all idle 1546.PP
1431watchers are being called again and again, once per event loop iteration \- 1547That is, as long as your process is busy handling sockets or timeouts
1548(or even signals, imagine) of the same or higher priority it will not be
1549triggered. But when your process is idle (or only lower-priority watchers
1550are pending), the idle watchers are being called once per event loop
1432until stopped, that is, or your process receives more events and becomes 1551iteration \- until stopped, that is, or your process receives more events
1433busy. 1552and becomes busy again with higher priority stuff.
1434.PP 1553.PP
1435The most noteworthy effect is that as long as any idle watchers are 1554The most noteworthy effect is that as long as any idle watchers are
1436active, the process will not block when waiting for new events. 1555active, the process will not block when waiting for new events.
1437.PP 1556.PP
1438Apart from keeping your process non-blocking (which is a useful 1557Apart from keeping your process non-blocking (which is a useful
… …
1443.IX Item "ev_idle_init (ev_signal *, callback)" 1562.IX Item "ev_idle_init (ev_signal *, callback)"
1444Initialises and configures the idle watcher \- it has no parameters of any 1563Initialises 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, 1564kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1446believe me. 1565believe me.
1447.PP 1566.PP
1448Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1567Example: 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. 1568callback, free it. Also, use no error checking, as usual.
1450.PP 1569.PP
1451.Vb 7 1570.Vb 7
1452\& static void 1571\& static void
1453\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1572\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1454\& { 1573\& {
… …
1533\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; 1652\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1534\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; 1653\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1535\& } 1654\& }
1536.Ve 1655.Ve
1537.PP 1656.PP
1538.Vb 7 1657.Vb 8
1539\& // create io watchers for each fd and a timer before blocking 1658\& // create io watchers for each fd and a timer before blocking
1540\& static void 1659\& static void
1541\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1660\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1542\& { 1661\& {
1543\& int timeout = 3600000;truct pollfd fds [nfd]; 1662\& int timeout = 3600000;
1663\& struct pollfd fds [nfd];
1544\& // actual code will need to loop here and realloc etc. 1664\& // actual code will need to loop here and realloc etc.
1545\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1665\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1546.Ve 1666.Ve
1547.PP 1667.PP
1548.Vb 3 1668.Vb 3
… …
1875\& } 1995\& }
1876.Ve 1996.Ve
1877.SH "MACRO MAGIC" 1997.SH "MACRO MAGIC"
1878.IX Header "MACRO MAGIC" 1998.IX Header "MACRO MAGIC"
1879Libev can be compiled with a variety of options, the most fundemantal is 1999Libev 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 2000\&\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. 2001callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1882.PP 2002.PP
1883To make it easier to write programs that cope with either variant, the 2003To make it easier to write programs that cope with either variant, the
1884following macros are defined: 2004following macros are defined:
1885.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2005.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
1920.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2040.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1921.IX Item "EV_DEFAULT, EV_DEFAULT_" 2041.IX Item "EV_DEFAULT, EV_DEFAULT_"
1922Similar to the other two macros, this gives you the value of the default 2042Similar to the other two macros, this gives you the value of the default
1923loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2043loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1924.PP 2044.PP
1925Example: Declare and initialise a check watcher, working regardless of 2045Example: Declare and initialise a check watcher, utilising the above
1926wether multiple loops are supported or not. 2046macros so it will work regardless of whether multiple loops are supported
2047or not.
1927.PP 2048.PP
1928.Vb 5 2049.Vb 5
1929\& static void 2050\& static void
1930\& check_cb (EV_P_ ev_timer *w, int revents) 2051\& check_cb (EV_P_ ev_timer *w, int revents)
1931\& { 2052\& {
… …
1994.Vb 1 2115.Vb 1
1995\& ev_win32.c required on win32 platforms only 2116\& ev_win32.c required on win32 platforms only
1996.Ve 2117.Ve
1997.PP 2118.PP
1998.Vb 5 2119.Vb 5
1999\& ev_select.c only when select backend is enabled (which is by default) 2120\& 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) 2121\& 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) 2122\& 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) 2123\& 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) 2124\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2004.Ve 2125.Ve
… …
2125otherwise another method will be used as fallback. This is the preferred 2246otherwise another method will be used as fallback. This is the preferred
2126backend for Solaris 10 systems. 2247backend for Solaris 10 systems.
2127.IP "\s-1EV_USE_DEVPOLL\s0" 4 2248.IP "\s-1EV_USE_DEVPOLL\s0" 4
2128.IX Item "EV_USE_DEVPOLL" 2249.IX Item "EV_USE_DEVPOLL"
2129reserved for future expansion, works like the \s-1USE\s0 symbols above. 2250reserved for future expansion, works like the \s-1USE\s0 symbols above.
2251.IP "\s-1EV_USE_INOTIFY\s0" 4
2252.IX Item "EV_USE_INOTIFY"
2253If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2254interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2255be detected at runtime.
2130.IP "\s-1EV_H\s0" 4 2256.IP "\s-1EV_H\s0" 4
2131.IX Item "EV_H" 2257.IX Item "EV_H"
2132The name of the \fIev.h\fR header file used to include it. The default if 2258The 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 2259undefined 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. 2260can 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 2278If 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 2279will 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 2280additional independent event loops. Otherwise there will be no support
2155for multiple event loops and there is no first event loop pointer 2281for multiple event loops and there is no first event loop pointer
2156argument. Instead, all functions act on the single default loop. 2282argument. Instead, all functions act on the single default loop.
2283.IP "\s-1EV_MINPRI\s0" 4
2284.IX Item "EV_MINPRI"
2285.PD 0
2286.IP "\s-1EV_MAXPRI\s0" 4
2287.IX Item "EV_MAXPRI"
2288.PD
2289The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2290\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2291provide for more priorities by overriding those symbols (usually defined
2292to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2293.Sp
2294When doing priority-based operations, libev usually has to linearly search
2295all the priorities, so having many of them (hundreds) uses a lot of space
2296and time, so using the defaults of five priorities (\-2 .. +2) is usually
2297fine.
2298.Sp
2299If your embedding app does not need any priorities, defining these both to
2300\&\f(CW0\fR will save some memory and cpu.
2157.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2301.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2158.IX Item "EV_PERIODIC_ENABLE" 2302.IX Item "EV_PERIODIC_ENABLE"
2159If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2303If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2304defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2305code.
2306.IP "\s-1EV_IDLE_ENABLE\s0" 4
2307.IX Item "EV_IDLE_ENABLE"
2308If 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 2309defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2161code. 2310code.
2162.IP "\s-1EV_EMBED_ENABLE\s0" 4 2311.IP "\s-1EV_EMBED_ENABLE\s0" 4
2163.IX Item "EV_EMBED_ENABLE" 2312.IX Item "EV_EMBED_ENABLE"
2164If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2313If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2179.IP "\s-1EV_PID_HASHSIZE\s0" 4 2328.IP "\s-1EV_PID_HASHSIZE\s0" 4
2180.IX Item "EV_PID_HASHSIZE" 2329.IX Item "EV_PID_HASHSIZE"
2181\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2330\&\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 2331pid. 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 2332than enough. If you need to manage thousands of children you might want to
2184increase this value. 2333increase this value (\fImust\fR be a power of two).
2334.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2335.IX Item "EV_INOTIFY_HASHSIZE"
2336\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2337inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2338usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2339watchers you might want to increase this value (\fImust\fR be a power of
2340two).
2185.IP "\s-1EV_COMMON\s0" 4 2341.IP "\s-1EV_COMMON\s0" 4
2186.IX Item "EV_COMMON" 2342.IX Item "EV_COMMON"
2187By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2343By 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 2344this 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, 2345members. 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 2375interface) 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 2376will be compiled. It is pretty complex because it provides its own header
2221file. 2377file.
2222.Sp 2378.Sp
2223The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2379The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2224that everybody includes and which overrides some autoconf choices: 2380that everybody includes and which overrides some configure choices:
2225.Sp 2381.Sp
2226.Vb 4 2382.Vb 9
2383\& #define EV_MINIMAL 1
2227\& #define EV_USE_POLL 0 2384\& #define EV_USE_POLL 0
2228\& #define EV_MULTIPLICITY 0 2385\& #define EV_MULTIPLICITY 0
2229\& #define EV_PERIODICS 0 2386\& #define EV_PERIODIC_ENABLE 0
2387\& #define EV_STAT_ENABLE 0
2388\& #define EV_FORK_ENABLE 0
2230\& #define EV_CONFIG_H <config.h> 2389\& #define EV_CONFIG_H <config.h>
2390\& #define EV_MINPRI 0
2391\& #define EV_MAXPRI 0
2231.Ve 2392.Ve
2232.Sp 2393.Sp
2233.Vb 1 2394.Vb 1
2234\& #include "ev++.h" 2395\& #include "ev++.h"
2235.Ve 2396.Ve
… …
2243.SH "COMPLEXITIES" 2404.SH "COMPLEXITIES"
2244.IX Header "COMPLEXITIES" 2405.IX Header "COMPLEXITIES"
2245In this section the complexities of (many of) the algorithms used inside 2406In this section the complexities of (many of) the algorithms used inside
2246libev will be explained. For complexity discussions about backends see the 2407libev will be explained. For complexity discussions about backends see the
2247documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2408documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2409.Sp
2410All of the following are about amortised time: If an array needs to be
2411extended, libev needs to realloc and move the whole array, but this
2412happens asymptotically never with higher number of elements, so O(1) might
2413mean it might do a lengthy realloc operation in rare cases, but on average
2414it is much faster and asymptotically approaches constant time.
2248.RS 4 2415.RS 4
2249.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2416.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)" 2417.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2251.PD 0 2418This means that, when you have a watcher that triggers in one hour and
2419there are 100 watchers that would trigger before that then inserting will
2420have to skip those 100 watchers.
2252.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2421.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)" 2422.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2423That means that for changing a timer costs less than removing/adding them
2424as 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 2425.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)" 2426.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2256.IP "Stopping check/prepare/idle watchers: O(1)" 4 2427These just add the watcher into an array or at the head of a list.
2257.IX Item "Stopping check/prepare/idle watchers: O(1)" 2428=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 2429.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))" 2430.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2431These watchers are stored in lists then need to be walked to find the
2432correct watcher to remove. The lists are usually short (you don't usually
2433have many watchers waiting for the same fd or signal).
2260.IP "Finding the next timer per loop iteration: O(1)" 4 2434.IP "Finding the next timer per loop iteration: O(1)" 4
2261.IX Item "Finding the next timer per loop iteration: O(1)" 2435.IX Item "Finding the next timer per loop iteration: O(1)"
2436.PD 0
2262.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2437.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)" 2438.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2439.PD
2440A change means an I/O watcher gets started or stopped, which requires
2441libev to recalculate its status (and possibly tell the kernel).
2264.IP "Activating one watcher: O(1)" 4 2442.IP "Activating one watcher: O(1)" 4
2265.IX Item "Activating one watcher: O(1)" 2443.IX Item "Activating one watcher: O(1)"
2444.PD 0
2445.IP "Priority handling: O(number_of_priorities)" 4
2446.IX Item "Priority handling: O(number_of_priorities)"
2447.PD
2448Priorities are implemented by allocating some space for each
2449priority. When doing priority-based operations, libev usually has to
2450linearly search all the priorities.
2266.RE 2451.RE
2267.RS 4 2452.RS 4
2268.PD
2269.SH "AUTHOR" 2453.SH "AUTHOR"
2270.IX Header "AUTHOR" 2454.IX Header "AUTHOR"
2271Marc Lehmann <libev@schmorp.de>. 2455Marc Lehmann <libev@schmorp.de>.

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