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Revision 1.24 by root, Tue Nov 27 10:59:10 2007 UTC vs.
Revision 1.36 by root, Thu Nov 29 20:05:59 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 "2007-11-29" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
138\& #include <ev.h> 138\& #include <ev.h>
139.Ve 139.Ve
140.SH "EXAMPLE PROGRAM"
141.IX Header "EXAMPLE PROGRAM"
142.Vb 1
143\& #include <ev.h>
144.Ve
145.PP
146.Vb 2
147\& ev_io stdin_watcher;
148\& ev_timer timeout_watcher;
149.Ve
150.PP
151.Vb 8
152\& /* called when data readable on stdin */
153\& static void
154\& stdin_cb (EV_P_ struct ev_io *w, int revents)
155\& {
156\& /* puts ("stdin ready"); */
157\& ev_io_stop (EV_A_ w); /* just a syntax example */
158\& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
159\& }
160.Ve
161.PP
162.Vb 6
163\& static void
164\& timeout_cb (EV_P_ struct ev_timer *w, int revents)
165\& {
166\& /* puts ("timeout"); */
167\& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
168\& }
169.Ve
170.PP
171.Vb 4
172\& int
173\& main (void)
174\& {
175\& struct ev_loop *loop = ev_default_loop (0);
176.Ve
177.PP
178.Vb 3
179\& /* initialise an io watcher, then start it */
180\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
181\& ev_io_start (loop, &stdin_watcher);
182.Ve
183.PP
184.Vb 3
185\& /* simple non-repeating 5.5 second timeout */
186\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
187\& ev_timer_start (loop, &timeout_watcher);
188.Ve
189.PP
190.Vb 2
191\& /* loop till timeout or data ready */
192\& ev_loop (loop, 0);
193.Ve
194.PP
195.Vb 2
196\& return 0;
197\& }
198.Ve
140.SH "DESCRIPTION" 199.SH "DESCRIPTION"
141.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
142Libev is an event loop: you register interest in certain events (such as a 201Libev is an event loop: you register interest in certain events (such as a
143file descriptor being readable or a timeout occuring), and it will manage 202file descriptor being readable or a timeout occuring), and it will manage
144these event sources and provide your program with events. 203these event sources and provide your program with events.
… …
151watchers\fR, which are relatively small C structures you initialise with the 210watchers\fR, which are relatively small C structures you initialise with the
152details of the event, and then hand it over to libev by \fIstarting\fR the 211details of the event, and then hand it over to libev by \fIstarting\fR the
153watcher. 212watcher.
154.SH "FEATURES" 213.SH "FEATURES"
155.IX Header "FEATURES" 214.IX Header "FEATURES"
156Libev supports select, poll, the linux-specific epoll and the bsd-specific 215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
157kqueue mechanisms for file descriptor events, relative timers, absolute 216BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
158timers with customised rescheduling, signal events, process status change 217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
159events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 218(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
160loop mechanism itself (idle, prepare and check watchers). It also is quite 219with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
161fast (see this benchmark comparing 220(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
162it to libevent for example). 221watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
222\&\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
223file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
224(\f(CW\*(C`ev_fork\*(C'\fR).
225.PP
226It also is quite fast (see this
227benchmark comparing it to libevent
228for example).
163.SH "CONVENTIONS" 229.SH "CONVENTIONS"
164.IX Header "CONVENTIONS" 230.IX Header "CONVENTIONS"
165Libev is very configurable. In this manual the default configuration 231Libev is very configurable. In this manual the default configuration will
166will be described, which supports multiple event loops. For more info 232be described, which supports multiple event loops. For more info about
167about various configuration options please have a look at the file 233various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
168\&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without 234this manual. If libev was configured without support for multiple event
169support for multiple event loops, then all functions taking an initial 235loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
170argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) 236(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
171will not have this argument.
172.SH "TIME REPRESENTATION" 237.SH "TIME REPRESENTATION"
173.IX Header "TIME REPRESENTATION" 238.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 239Libev represents time as a single floating point number, representing the
175(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 240(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
176the beginning of 1970, details are complicated, don't ask). This type is 241the beginning of 1970, details are complicated, don't ask). This type is
… …
201Usually, it's a good idea to terminate if the major versions mismatch, 266Usually, it's a good idea to terminate if the major versions mismatch,
202as this indicates an incompatible change. Minor versions are usually 267as this indicates an incompatible change. Minor versions are usually
203compatible to older versions, so a larger minor version alone is usually 268compatible to older versions, so a larger minor version alone is usually
204not a problem. 269not a problem.
205.Sp 270.Sp
206Example: make sure we haven't accidentally been linked against the wrong 271Example: Make sure we haven't accidentally been linked against the wrong
207version: 272version.
208.Sp 273.Sp
209.Vb 3 274.Vb 3
210\& assert (("libev version mismatch", 275\& assert (("libev version mismatch",
211\& ev_version_major () == EV_VERSION_MAJOR 276\& ev_version_major () == EV_VERSION_MAJOR
212\& && ev_version_minor () >= EV_VERSION_MINOR)); 277\& && ev_version_minor () >= EV_VERSION_MINOR));
… …
242recommended ones. 307recommended ones.
243.Sp 308.Sp
244See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 309See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
245.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 310.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
246.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 311.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
247Sets the allocation function to use (the prototype is similar to the 312Sets the allocation function to use (the prototype is similar \- the
248realloc C function, the semantics are identical). It is used to allocate 313semantics is identical \- to the realloc C function). It is used to
249and free memory (no surprises here). If it returns zero when memory 314allocate and free memory (no surprises here). If it returns zero when
250needs to be allocated, the library might abort or take some potentially 315memory needs to be allocated, the library might abort or take some
251destructive action. The default is your system realloc function. 316potentially destructive action. The default is your system realloc
317function.
252.Sp 318.Sp
253You could override this function in high-availability programs to, say, 319You could override this function in high-availability programs to, say,
254free some memory if it cannot allocate memory, to use a special allocator, 320free some memory if it cannot allocate memory, to use a special allocator,
255or even to sleep a while and retry until some memory is available. 321or even to sleep a while and retry until some memory is available.
256.Sp 322.Sp
257Example: replace the libev allocator with one that waits a bit and then 323Example: Replace the libev allocator with one that waits a bit and then
258retries: better than mine). 324retries).
259.Sp 325.Sp
260.Vb 6 326.Vb 6
261\& static void * 327\& static void *
262\& persistent_realloc (void *ptr, long size) 328\& persistent_realloc (void *ptr, size_t size)
263\& { 329\& {
264\& for (;;) 330\& for (;;)
265\& { 331\& {
266\& void *newptr = realloc (ptr, size); 332\& void *newptr = realloc (ptr, size);
267.Ve 333.Ve
… …
289callback is set, then libev will expect it to remedy the sitution, no 355callback is set, then libev will expect it to remedy the sitution, no
290matter what, when it returns. That is, libev will generally retry the 356matter what, when it returns. That is, libev will generally retry the
291requested operation, or, if the condition doesn't go away, do bad stuff 357requested operation, or, if the condition doesn't go away, do bad stuff
292(such as abort). 358(such as abort).
293.Sp 359.Sp
294Example: do the same thing as libev does internally: 360Example: This is basically the same thing that libev does internally, too.
295.Sp 361.Sp
296.Vb 6 362.Vb 6
297\& static void 363\& static void
298\& fatal_error (const char *msg) 364\& fatal_error (const char *msg)
299\& { 365\& {
… …
345or setgid) then libev will \fInot\fR look at the environment variable 411or setgid) then libev will \fInot\fR look at the environment variable
346\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 412\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
347override the flags completely if it is found in the environment. This is 413override the flags completely if it is found in the environment. This is
348useful to try out specific backends to test their performance, or to work 414useful to try out specific backends to test their performance, or to work
349around bugs. 415around bugs.
416.ie n .IP """EVFLAG_FORKCHECK""" 4
417.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
418.IX Item "EVFLAG_FORKCHECK"
419Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
420a fork, you can also make libev check for a fork in each iteration by
421enabling this flag.
422.Sp
423This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
424and thus this might slow down your event loop if you do a lot of loop
425iterations and little real work, but is usually not noticable (on my
426Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
427without a syscall and thus \fIvery\fR fast, but my Linux system also has
428\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
429.Sp
430The big advantage of this flag is that you can forget about fork (and
431forget about forgetting to tell libev about forking) when you use this
432flag.
433.Sp
434This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
435environment variable.
350.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 436.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
351.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 437.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
352.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 438.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
353This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 439This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
354libev tries to roll its own fd_set with no limits on the number of fds, 440libev tries to roll its own fd_set with no limits on the number of fds,
… …
448Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 534Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
449always distinct from the default loop. Unlike the default loop, it cannot 535always distinct from the default loop. Unlike the default loop, it cannot
450handle signal and child watchers, and attempts to do so will be greeted by 536handle signal and child watchers, and attempts to do so will be greeted by
451undefined behaviour (or a failed assertion if assertions are enabled). 537undefined behaviour (or a failed assertion if assertions are enabled).
452.Sp 538.Sp
453Example: try to create a event loop that uses epoll and nothing else. 539Example: Try to create a event loop that uses epoll and nothing else.
454.Sp 540.Sp
455.Vb 3 541.Vb 3
456\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 542\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457\& if (!epoller) 543\& if (!epoller)
458\& fatal ("no epoll found here, maybe it hides under your chair"); 544\& fatal ("no epoll found here, maybe it hides under your chair");
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556\& be handled here by queueing them when their watcher gets executed. 642\& be handled here by queueing them when their watcher gets executed.
557\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 643\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
558\& were used, return, otherwise continue with step *. 644\& were used, return, otherwise continue with step *.
559.Ve 645.Ve
560.Sp 646.Sp
561Example: queue some jobs and then loop until no events are outsanding 647Example: Queue some jobs and then loop until no events are outsanding
562anymore. 648anymore.
563.Sp 649.Sp
564.Vb 4 650.Vb 4
565\& ... queue jobs here, make sure they register event watchers as long 651\& ... queue jobs here, make sure they register event watchers as long
566\& ... as they still have work to do (even an idle watcher will do..) 652\& ... as they still have work to do (even an idle watcher will do..)
… …
588visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 674visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
589no event watchers registered by it are active. It is also an excellent 675no event watchers registered by it are active. It is also an excellent
590way to do this for generic recurring timers or from within third-party 676way to do this for generic recurring timers or from within third-party
591libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 677libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592.Sp 678.Sp
593Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 679Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594running when nothing else is active. 680running when nothing else is active.
595.Sp 681.Sp
596.Vb 4 682.Vb 4
597\& struct dv_signal exitsig; 683\& struct ev_signal exitsig;
598\& ev_signal_init (&exitsig, sig_cb, SIGINT); 684\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599\& ev_signal_start (myloop, &exitsig); 685\& ev_signal_start (loop, &exitsig);
600\& evf_unref (myloop); 686\& evf_unref (loop);
601.Ve 687.Ve
602.Sp 688.Sp
603Example: for some weird reason, unregister the above signal handler again. 689Example: For some weird reason, unregister the above signal handler again.
604.Sp 690.Sp
605.Vb 2 691.Vb 2
606\& ev_ref (myloop); 692\& ev_ref (loop);
607\& ev_signal_stop (myloop, &exitsig); 693\& ev_signal_stop (loop, &exitsig);
608.Ve 694.Ve
609.SH "ANATOMY OF A WATCHER" 695.SH "ANATOMY OF A WATCHER"
610.IX Header "ANATOMY OF A WATCHER" 696.IX Header "ANATOMY OF A WATCHER"
611A watcher is a structure that you create and register to record your 697A watcher is a structure that you create and register to record your
612interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 698interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
792Returns a true value iff the watcher is pending, (i.e. it has outstanding 878Returns a true value iff the watcher is pending, (i.e. it has outstanding
793events but its callback has not yet been invoked). As long as a watcher 879events but its callback has not yet been invoked). As long as a watcher
794is pending (but not active) you must not call an init function on it (but 880is pending (but not active) you must not call an init function on it (but
795\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 881\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
796libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 882libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
797.IP "callback = ev_cb (ev_TYPE *watcher)" 4 883.IP "callback ev_cb (ev_TYPE *watcher)" 4
798.IX Item "callback = ev_cb (ev_TYPE *watcher)" 884.IX Item "callback ev_cb (ev_TYPE *watcher)"
799Returns the callback currently set on the watcher. 885Returns the callback currently set on the watcher.
800.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 886.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
801.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 887.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
802Change the callback. You can change the callback at virtually any time 888Change the callback. You can change the callback at virtually any time
803(modulo threads). 889(modulo threads).
… …
829\& struct my_io *w = (struct my_io *)w_; 915\& struct my_io *w = (struct my_io *)w_;
830\& ... 916\& ...
831\& } 917\& }
832.Ve 918.Ve
833.PP 919.PP
834More interesting and less C\-conformant ways of catsing your callback type 920More interesting and less C\-conformant ways of casting your callback type
835have been omitted.... 921instead have been omitted.
922.PP
923Another common scenario is having some data structure with multiple
924watchers:
925.PP
926.Vb 6
927\& struct my_biggy
928\& {
929\& int some_data;
930\& ev_timer t1;
931\& ev_timer t2;
932\& }
933.Ve
934.PP
935In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
936you need to use \f(CW\*(C`offsetof\*(C'\fR:
937.PP
938.Vb 1
939\& #include <stddef.h>
940.Ve
941.PP
942.Vb 6
943\& static void
944\& t1_cb (EV_P_ struct ev_timer *w, int revents)
945\& {
946\& struct my_biggy big = (struct my_biggy *
947\& (((char *)w) - offsetof (struct my_biggy, t1));
948\& }
949.Ve
950.PP
951.Vb 6
952\& static void
953\& t2_cb (EV_P_ struct ev_timer *w, int revents)
954\& {
955\& struct my_biggy big = (struct my_biggy *
956\& (((char *)w) - offsetof (struct my_biggy, t2));
957\& }
958.Ve
836.SH "WATCHER TYPES" 959.SH "WATCHER TYPES"
837.IX Header "WATCHER TYPES" 960.IX Header "WATCHER TYPES"
838This section describes each watcher in detail, but will not repeat 961This section describes each watcher in detail, but will not repeat
839information given in the last section. Any initialisation/set macros, 962information given in the last section. Any initialisation/set macros,
840functions and members specific to the watcher type are explained. 963functions and members specific to the watcher type are explained.
… …
901The file descriptor being watched. 1024The file descriptor being watched.
902.IP "int events [read\-only]" 4 1025.IP "int events [read\-only]" 4
903.IX Item "int events [read-only]" 1026.IX Item "int events [read-only]"
904The events being watched. 1027The events being watched.
905.PP 1028.PP
906Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1029Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
907readable, but only once. Since it is likely line\-buffered, you could 1030readable, but only once. Since it is likely line\-buffered, you could
908attempt to read a whole line in the callback: 1031attempt to read a whole line in the callback.
909.PP 1032.PP
910.Vb 6 1033.Vb 6
911\& static void 1034\& static void
912\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1035\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
913\& { 1036\& {
… …
968.IP "ev_timer_again (loop)" 4 1091.IP "ev_timer_again (loop)" 4
969.IX Item "ev_timer_again (loop)" 1092.IX Item "ev_timer_again (loop)"
970This will act as if the timer timed out and restart it again if it is 1093This will act as if the timer timed out and restart it again if it is
971repeating. The exact semantics are: 1094repeating. The exact semantics are:
972.Sp 1095.Sp
1096If the timer is pending, its pending status is cleared.
1097.Sp
973If the timer is started but nonrepeating, stop it. 1098If the timer is started but nonrepeating, stop it (as if it timed out).
974.Sp 1099.Sp
975If the timer is repeating, either start it if necessary (with the repeat 1100If the timer is repeating, either start it if necessary (with the
976value), or reset the running timer to the repeat value. 1101\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
977.Sp 1102.Sp
978This sounds a bit complicated, but here is a useful and typical 1103This sounds a bit complicated, but here is a useful and typical
979example: Imagine you have a tcp connection and you want a so-called 1104example: Imagine you have a tcp connection and you want a so-called idle
980idle timeout, that is, you want to be called when there have been, 1105timeout, that is, you want to be called when there have been, say, 60
981say, 60 seconds of inactivity on the socket. The easiest way to do 1106seconds of inactivity on the socket. The easiest way to do this is to
982this 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 1107configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
983\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1108\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
984you go into an idle state where you do not expect data to travel on the 1109you go into an idle state where you do not expect data to travel on the
985socket, you can stop the timer, and again will automatically restart it if 1110socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
986need be. 1111automatically restart it if need be.
987.Sp 1112.Sp
988You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1113That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
989and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1114altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
990.Sp 1115.Sp
991.Vb 8 1116.Vb 8
992\& ev_timer_init (timer, callback, 0., 5.); 1117\& ev_timer_init (timer, callback, 0., 5.);
993\& ev_timer_again (loop, timer); 1118\& ev_timer_again (loop, timer);
994\& ... 1119\& ...
… …
997\& ... 1122\& ...
998\& timer->again = 10.; 1123\& timer->again = 10.;
999\& ev_timer_again (loop, timer); 1124\& ev_timer_again (loop, timer);
1000.Ve 1125.Ve
1001.Sp 1126.Sp
1002This is more efficient then stopping/starting the timer eahc time you want 1127This is more slightly efficient then stopping/starting the timer each time
1003to modify its timeout value. 1128you want to modify its timeout value.
1004.IP "ev_tstamp repeat [read\-write]" 4 1129.IP "ev_tstamp repeat [read\-write]" 4
1005.IX Item "ev_tstamp repeat [read-write]" 1130.IX Item "ev_tstamp repeat [read-write]"
1006The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1131The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1007or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1132or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1008which is also when any modifications are taken into account. 1133which is also when any modifications are taken into account.
1009.PP 1134.PP
1010Example: create a timer that fires after 60 seconds. 1135Example: Create a timer that fires after 60 seconds.
1011.PP 1136.PP
1012.Vb 5 1137.Vb 5
1013\& static void 1138\& static void
1014\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1139\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1015\& { 1140\& {
… …
1021\& struct ev_timer mytimer; 1146\& struct ev_timer mytimer;
1022\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1147\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1023\& ev_timer_start (loop, &mytimer); 1148\& ev_timer_start (loop, &mytimer);
1024.Ve 1149.Ve
1025.PP 1150.PP
1026Example: create a timeout timer that times out after 10 seconds of 1151Example: Create a timeout timer that times out after 10 seconds of
1027inactivity. 1152inactivity.
1028.PP 1153.PP
1029.Vb 5 1154.Vb 5
1030\& static void 1155\& static void
1031\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1156\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
1156.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1281.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1157The current reschedule callback, or \f(CW0\fR, if this functionality is 1282The current reschedule callback, or \f(CW0\fR, if this functionality is
1158switched off. Can be changed any time, but changes only take effect when 1283switched off. Can be changed any time, but changes only take effect when
1159the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1284the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1160.PP 1285.PP
1161Example: call a callback every hour, or, more precisely, whenever the 1286Example: Call a callback every hour, or, more precisely, whenever the
1162system clock is divisible by 3600. The callback invocation times have 1287system clock is divisible by 3600. The callback invocation times have
1163potentially a lot of jittering, but good long-term stability. 1288potentially a lot of jittering, but good long-term stability.
1164.PP 1289.PP
1165.Vb 5 1290.Vb 5
1166\& static void 1291\& static void
… …
1174\& struct ev_periodic hourly_tick; 1299\& struct ev_periodic hourly_tick;
1175\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1300\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1176\& ev_periodic_start (loop, &hourly_tick); 1301\& ev_periodic_start (loop, &hourly_tick);
1177.Ve 1302.Ve
1178.PP 1303.PP
1179Example: the same as above, but use a reschedule callback to do it: 1304Example: The same as above, but use a reschedule callback to do it:
1180.PP 1305.PP
1181.Vb 1 1306.Vb 1
1182\& #include <math.h> 1307\& #include <math.h>
1183.Ve 1308.Ve
1184.PP 1309.PP
… …
1192.PP 1317.PP
1193.Vb 1 1318.Vb 1
1194\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1319\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1195.Ve 1320.Ve
1196.PP 1321.PP
1197Example: call a callback every hour, starting now: 1322Example: Call a callback every hour, starting now:
1198.PP 1323.PP
1199.Vb 4 1324.Vb 4
1200\& struct ev_periodic hourly_tick; 1325\& struct ev_periodic hourly_tick;
1201\& ev_periodic_init (&hourly_tick, clock_cb, 1326\& ev_periodic_init (&hourly_tick, clock_cb,
1202\& fmod (ev_now (loop), 3600.), 3600., 0); 1327\& fmod (ev_now (loop), 3600.), 3600., 0);
… …
1253.IP "int rstatus [read\-write]" 4 1378.IP "int rstatus [read\-write]" 4
1254.IX Item "int rstatus [read-write]" 1379.IX Item "int rstatus [read-write]"
1255The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems 1380The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1256\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). 1381\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1257.PP 1382.PP
1258Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1383Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1259.PP 1384.PP
1260.Vb 5 1385.Vb 5
1261\& static void 1386\& static void
1262\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1387\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1263\& { 1388\& {
… …
1281not exist\*(R" is a status change like any other. The condition \*(L"path does 1406not exist\*(R" is a status change like any other. The condition \*(L"path does
1282not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1407not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1283otherwise always forced to be at least one) and all the other fields of 1408otherwise always forced to be at least one) and all the other fields of
1284the stat buffer having unspecified contents. 1409the stat buffer having unspecified contents.
1285.PP 1410.PP
1411The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1412relative and your working directory changes, the behaviour is undefined.
1413.PP
1286Since there is no standard to do this, the portable implementation simply 1414Since there is no standard to do this, the portable implementation simply
1287calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1415calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1288can specify a recommended polling interval for this case. If you specify 1416can specify a recommended polling interval for this case. If you specify
1289a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1417a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1290unspecified default\fR value will be used (which you can expect to be around 1418unspecified default\fR value will be used (which you can expect to be around
1291five seconds, although this might change dynamically). Libev will also 1419five seconds, although this might change dynamically). Libev will also
1292impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1420impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1294.PP 1422.PP
1295This watcher type is not meant for massive numbers of stat watchers, 1423This watcher type is not meant for massive numbers of stat watchers,
1296as even with OS-supported change notifications, this can be 1424as even with OS-supported change notifications, this can be
1297resource\-intensive. 1425resource\-intensive.
1298.PP 1426.PP
1299At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1427At the time of this writing, only the Linux inotify interface is
1300if demand increases, at least a kqueue and inotify backend will be added. 1428implemented (implementing kqueue support is left as an exercise for the
1429reader). Inotify will be used to give hints only and should not change the
1430semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1431to fall back to regular polling again even with inotify, but changes are
1432usually detected immediately, and if the file exists there will be no
1433polling.
1301.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1434.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1302.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1435.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1303.PD 0 1436.PD 0
1304.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1437.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1305.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1438.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1387.IX Item "ev_idle_init (ev_signal *, callback)" 1520.IX Item "ev_idle_init (ev_signal *, callback)"
1388Initialises and configures the idle watcher \- it has no parameters of any 1521Initialises and configures the idle watcher \- it has no parameters of any
1389kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1522kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1390believe me. 1523believe me.
1391.PP 1524.PP
1392Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1525Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1393callback, free it. Alos, use no error checking, as usual. 1526callback, free it. Also, use no error checking, as usual.
1394.PP 1527.PP
1395.Vb 7 1528.Vb 7
1396\& static void 1529\& static void
1397\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1530\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1398\& { 1531\& {
… …
1864.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 1997.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1865.IX Item "EV_DEFAULT, EV_DEFAULT_" 1998.IX Item "EV_DEFAULT, EV_DEFAULT_"
1866Similar to the other two macros, this gives you the value of the default 1999Similar to the other two macros, this gives you the value of the default
1867loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2000loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1868.PP 2001.PP
1869Example: Declare and initialise a check watcher, working regardless of 2002Example: Declare and initialise a check watcher, utilising the above
1870wether multiple loops are supported or not. 2003macros so it will work regardless of wether multiple loops are supported
2004or not.
1871.PP 2005.PP
1872.Vb 5 2006.Vb 5
1873\& static void 2007\& static void
1874\& check_cb (EV_P_ ev_timer *w, int revents) 2008\& check_cb (EV_P_ ev_timer *w, int revents)
1875\& { 2009\& {
… …
1938.Vb 1 2072.Vb 1
1939\& ev_win32.c required on win32 platforms only 2073\& ev_win32.c required on win32 platforms only
1940.Ve 2074.Ve
1941.PP 2075.PP
1942.Vb 5 2076.Vb 5
1943\& ev_select.c only when select backend is enabled (which is by default) 2077\& ev_select.c only when select backend is enabled (which is enabled by default)
1944\& ev_poll.c only when poll backend is enabled (disabled by default) 2078\& ev_poll.c only when poll backend is enabled (disabled by default)
1945\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2079\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
1946\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2080\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1947\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2081\& ev_port.c only when the solaris port backend is enabled (disabled by default)
1948.Ve 2082.Ve
… …
2069otherwise another method will be used as fallback. This is the preferred 2203otherwise another method will be used as fallback. This is the preferred
2070backend for Solaris 10 systems. 2204backend for Solaris 10 systems.
2071.IP "\s-1EV_USE_DEVPOLL\s0" 4 2205.IP "\s-1EV_USE_DEVPOLL\s0" 4
2072.IX Item "EV_USE_DEVPOLL" 2206.IX Item "EV_USE_DEVPOLL"
2073reserved for future expansion, works like the \s-1USE\s0 symbols above. 2207reserved for future expansion, works like the \s-1USE\s0 symbols above.
2208.IP "\s-1EV_USE_INOTIFY\s0" 4
2209.IX Item "EV_USE_INOTIFY"
2210If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2211interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2212be detected at runtime.
2074.IP "\s-1EV_H\s0" 4 2213.IP "\s-1EV_H\s0" 4
2075.IX Item "EV_H" 2214.IX Item "EV_H"
2076The name of the \fIev.h\fR header file used to include it. The default if 2215The name of the \fIev.h\fR header file used to include it. The default if
2077undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2216undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2078can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2217can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2118.IP "\s-1EV_MINIMAL\s0" 4 2257.IP "\s-1EV_MINIMAL\s0" 4
2119.IX Item "EV_MINIMAL" 2258.IX Item "EV_MINIMAL"
2120If you need to shave off some kilobytes of code at the expense of some 2259If you need to shave off some kilobytes of code at the expense of some
2121speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override 2260speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
2122some inlining decisions, saves roughly 30% codesize of amd64. 2261some inlining decisions, saves roughly 30% codesize of amd64.
2262.IP "\s-1EV_PID_HASHSIZE\s0" 4
2263.IX Item "EV_PID_HASHSIZE"
2264\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2265pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2266than enough. If you need to manage thousands of children you might want to
2267increase this value (\fImust\fR be a power of two).
2268.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2269.IX Item "EV_INOTIFY_HASHSIZE"
2270\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2271inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2272usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2273watchers you might want to increase this value (\fImust\fR be a power of
2274two).
2123.IP "\s-1EV_COMMON\s0" 4 2275.IP "\s-1EV_COMMON\s0" 4
2124.IX Item "EV_COMMON" 2276.IX Item "EV_COMMON"
2125By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2277By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2126this macro to a something else you can include more and other types of 2278this macro to a something else you can include more and other types of
2127members. You have to define it each time you include one of the files, 2279members. You have to define it each time you include one of the files,
… …
2157interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2309interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2158will be compiled. It is pretty complex because it provides its own header 2310will be compiled. It is pretty complex because it provides its own header
2159file. 2311file.
2160.Sp 2312.Sp
2161The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2313The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2162that everybody includes and which overrides some autoconf choices: 2314that everybody includes and which overrides some configure choices:
2163.Sp 2315.Sp
2164.Vb 4 2316.Vb 9
2317\& #define EV_MINIMAL 1
2165\& #define EV_USE_POLL 0 2318\& #define EV_USE_POLL 0
2166\& #define EV_MULTIPLICITY 0 2319\& #define EV_MULTIPLICITY 0
2167\& #define EV_PERIODICS 0 2320\& #define EV_PERIODIC_ENABLE 0
2321\& #define EV_STAT_ENABLE 0
2322\& #define EV_FORK_ENABLE 0
2168\& #define EV_CONFIG_H <config.h> 2323\& #define EV_CONFIG_H <config.h>
2324\& #define EV_MINPRI 0
2325\& #define EV_MAXPRI 0
2169.Ve 2326.Ve
2170.Sp 2327.Sp
2171.Vb 1 2328.Vb 1
2172\& #include "ev++.h" 2329\& #include "ev++.h"
2173.Ve 2330.Ve
… …
2191.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2348.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2192.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2349.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2193.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2350.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2194.IP "Stopping check/prepare/idle watchers: O(1)" 4 2351.IP "Stopping check/prepare/idle watchers: O(1)" 4
2195.IX Item "Stopping check/prepare/idle watchers: O(1)" 2352.IX Item "Stopping check/prepare/idle watchers: O(1)"
2196.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2353.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2197.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2354.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2198.IP "Finding the next timer per loop iteration: O(1)" 4 2355.IP "Finding the next timer per loop iteration: O(1)" 4
2199.IX Item "Finding the next timer per loop iteration: O(1)" 2356.IX Item "Finding the next timer per loop iteration: O(1)"
2200.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2357.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2201.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2358.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2202.IP "Activating one watcher: O(1)" 4 2359.IP "Activating one watcher: O(1)" 4

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