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Revision 1.14 by root, Sat Nov 24 10:10:26 2007 UTC vs.
Revision 1.33 by root, Wed Nov 28 18:29:29 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 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-28" "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\& {
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448Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 514Similar 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 515always 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 516handle signal and child watchers, and attempts to do so will be greeted by
451undefined behaviour (or a failed assertion if assertions are enabled). 517undefined behaviour (or a failed assertion if assertions are enabled).
452.Sp 518.Sp
453Example: try to create a event loop that uses epoll and nothing else. 519Example: Try to create a event loop that uses epoll and nothing else.
454.Sp 520.Sp
455.Vb 3 521.Vb 3
456\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 522\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457\& if (!epoller) 523\& if (!epoller)
458\& fatal ("no epoll found here, maybe it hides under your chair"); 524\& 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. 622\& be handled here by queueing them when their watcher gets executed.
557\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 623\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
558\& were used, return, otherwise continue with step *. 624\& were used, return, otherwise continue with step *.
559.Ve 625.Ve
560.Sp 626.Sp
561Example: queue some jobs and then loop until no events are outsanding 627Example: Queue some jobs and then loop until no events are outsanding
562anymore. 628anymore.
563.Sp 629.Sp
564.Vb 4 630.Vb 4
565\& ... queue jobs here, make sure they register event watchers as long 631\& ... 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..) 632\& ... 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 654visible 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 655no 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 656way 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. 657libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592.Sp 658.Sp
593Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 659Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594running when nothing else is active. 660running when nothing else is active.
595.Sp 661.Sp
596.Vb 4 662.Vb 4
597\& struct dv_signal exitsig; 663\& struct ev_signal exitsig;
598\& ev_signal_init (&exitsig, sig_cb, SIGINT); 664\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599\& ev_signal_start (myloop, &exitsig); 665\& ev_signal_start (loop, &exitsig);
600\& evf_unref (myloop); 666\& evf_unref (loop);
601.Ve 667.Ve
602.Sp 668.Sp
603Example: for some weird reason, unregister the above signal handler again. 669Example: For some weird reason, unregister the above signal handler again.
604.Sp 670.Sp
605.Vb 2 671.Vb 2
606\& ev_ref (myloop); 672\& ev_ref (loop);
607\& ev_signal_stop (myloop, &exitsig); 673\& ev_signal_stop (loop, &exitsig);
608.Ve 674.Ve
609.SH "ANATOMY OF A WATCHER" 675.SH "ANATOMY OF A WATCHER"
610.IX Header "ANATOMY OF A WATCHER" 676.IX Header "ANATOMY OF A WATCHER"
611A watcher is a structure that you create and register to record your 677A 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 678interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
684The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. 750The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
685.ie n .IP """EV_CHILD""" 4 751.ie n .IP """EV_CHILD""" 4
686.el .IP "\f(CWEV_CHILD\fR" 4 752.el .IP "\f(CWEV_CHILD\fR" 4
687.IX Item "EV_CHILD" 753.IX Item "EV_CHILD"
688The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. 754The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
755.ie n .IP """EV_STAT""" 4
756.el .IP "\f(CWEV_STAT\fR" 4
757.IX Item "EV_STAT"
758The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
689.ie n .IP """EV_IDLE""" 4 759.ie n .IP """EV_IDLE""" 4
690.el .IP "\f(CWEV_IDLE\fR" 4 760.el .IP "\f(CWEV_IDLE\fR" 4
691.IX Item "EV_IDLE" 761.IX Item "EV_IDLE"
692The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. 762The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
693.ie n .IP """EV_PREPARE""" 4 763.ie n .IP """EV_PREPARE""" 4
… …
703\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any 773\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
704received events. Callbacks of both watcher types can start and stop as 774received events. Callbacks of both watcher types can start and stop as
705many watchers as they want, and all of them will be taken into account 775many watchers as they want, and all of them will be taken into account
706(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep 776(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
707\&\f(CW\*(C`ev_loop\*(C'\fR from blocking). 777\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
778.ie n .IP """EV_EMBED""" 4
779.el .IP "\f(CWEV_EMBED\fR" 4
780.IX Item "EV_EMBED"
781The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
782.ie n .IP """EV_FORK""" 4
783.el .IP "\f(CWEV_FORK\fR" 4
784.IX Item "EV_FORK"
785The event loop has been resumed in the child process after fork (see
786\&\f(CW\*(C`ev_fork\*(C'\fR).
708.ie n .IP """EV_ERROR""" 4 787.ie n .IP """EV_ERROR""" 4
709.el .IP "\f(CWEV_ERROR\fR" 4 788.el .IP "\f(CWEV_ERROR\fR" 4
710.IX Item "EV_ERROR" 789.IX Item "EV_ERROR"
711An unspecified error has occured, the watcher has been stopped. This might 790An unspecified error has occured, the watcher has been stopped. This might
712happen because the watcher could not be properly started because libev 791happen because the watcher could not be properly started because libev
… …
717Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 796Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
718for example it might indicate that a fd is readable or writable, and if 797for example it might indicate that a fd is readable or writable, and if
719your callbacks is well-written it can just attempt the operation and cope 798your callbacks is well-written it can just attempt the operation and cope
720with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 799with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
721programs, though, so beware. 800programs, though, so beware.
722.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 801.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
723.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS" 802.IX Subsection "GENERIC WATCHER FUNCTIONS"
724In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, 803In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
725e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. 804e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers.
726.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 805.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
727.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 806.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
728.IX Item "ev_init (ev_TYPE *watcher, callback)" 807.IX Item "ev_init (ev_TYPE *watcher, callback)"
… …
734which rolls both calls into one. 813which rolls both calls into one.
735.Sp 814.Sp
736You can reinitialise a watcher at any time as long as it has been stopped 815You can reinitialise a watcher at any time as long as it has been stopped
737(or never started) and there are no pending events outstanding. 816(or never started) and there are no pending events outstanding.
738.Sp 817.Sp
739The callbakc is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, 818The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
740int revents)\*(C'\fR. 819int revents)\*(C'\fR.
741.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 820.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
742.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 821.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
743.IX Item "ev_TYPE_set (ev_TYPE *, [args])" 822.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
744This macro initialises the type-specific parts of a watcher. You need to 823This macro initialises the type-specific parts of a watcher. You need to
… …
779Returns a true value iff the watcher is pending, (i.e. it has outstanding 858Returns a true value iff the watcher is pending, (i.e. it has outstanding
780events but its callback has not yet been invoked). As long as a watcher 859events but its callback has not yet been invoked). As long as a watcher
781is pending (but not active) you must not call an init function on it (but 860is pending (but not active) you must not call an init function on it (but
782\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 861\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
783libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 862libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
784.IP "callback = ev_cb (ev_TYPE *watcher)" 4 863.IP "callback ev_cb (ev_TYPE *watcher)" 4
785.IX Item "callback = ev_cb (ev_TYPE *watcher)" 864.IX Item "callback ev_cb (ev_TYPE *watcher)"
786Returns the callback currently set on the watcher. 865Returns the callback currently set on the watcher.
787.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 866.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
788.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 867.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
789Change the callback. You can change the callback at virtually any time 868Change the callback. You can change the callback at virtually any time
790(modulo threads). 869(modulo threads).
… …
816\& struct my_io *w = (struct my_io *)w_; 895\& struct my_io *w = (struct my_io *)w_;
817\& ... 896\& ...
818\& } 897\& }
819.Ve 898.Ve
820.PP 899.PP
821More interesting and less C\-conformant ways of catsing your callback type 900More interesting and less C\-conformant ways of casting your callback type
822have been omitted.... 901instead have been omitted.
902.PP
903Another common scenario is having some data structure with multiple
904watchers:
905.PP
906.Vb 6
907\& struct my_biggy
908\& {
909\& int some_data;
910\& ev_timer t1;
911\& ev_timer t2;
912\& }
913.Ve
914.PP
915In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
916you need to use \f(CW\*(C`offsetof\*(C'\fR:
917.PP
918.Vb 1
919\& #include <stddef.h>
920.Ve
921.PP
922.Vb 6
923\& static void
924\& t1_cb (EV_P_ struct ev_timer *w, int revents)
925\& {
926\& struct my_biggy big = (struct my_biggy *
927\& (((char *)w) - offsetof (struct my_biggy, t1));
928\& }
929.Ve
930.PP
931.Vb 6
932\& static void
933\& t2_cb (EV_P_ struct ev_timer *w, int revents)
934\& {
935\& struct my_biggy big = (struct my_biggy *
936\& (((char *)w) - offsetof (struct my_biggy, t2));
937\& }
938.Ve
823.SH "WATCHER TYPES" 939.SH "WATCHER TYPES"
824.IX Header "WATCHER TYPES" 940.IX Header "WATCHER TYPES"
825This section describes each watcher in detail, but will not repeat 941This section describes each watcher in detail, but will not repeat
826information given in the last section. 942information given in the last section. Any initialisation/set macros,
943functions and members specific to the watcher type are explained.
944.PP
945Members are additionally marked with either \fI[read\-only]\fR, meaning that,
946while the watcher is active, you can look at the member and expect some
947sensible content, but you must not modify it (you can modify it while the
948watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
949means you can expect it to have some sensible content while the watcher
950is active, but you can also modify it. Modifying it may not do something
951sensible or take immediate effect (or do anything at all), but libev will
952not crash or malfunction in any way.
827.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 953.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
828.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" 954.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
829.IX Subsection "ev_io - is this file descriptor readable or writable" 955.IX Subsection "ev_io - is this file descriptor readable or writable?"
830I/O watchers check whether a file descriptor is readable or writable 956I/O watchers check whether a file descriptor is readable or writable
831in each iteration of the event loop (This behaviour is called 957in each iteration of the event loop, or, more precisely, when reading
832level-triggering because you keep receiving events as long as the 958would not block the process and writing would at least be able to write
833condition persists. Remember you can stop the watcher if you don't want to 959some data. This behaviour is called level-triggering because you keep
834act on the event and neither want to receive future events). 960receiving events as long as the condition persists. Remember you can stop
961the watcher if you don't want to act on the event and neither want to
962receive future events.
835.PP 963.PP
836In general you can register as many read and/or write event watchers per 964In general you can register as many read and/or write event watchers per
837fd as you want (as long as you don't confuse yourself). Setting all file 965fd as you want (as long as you don't confuse yourself). Setting all file
838descriptors to non-blocking mode is also usually a good idea (but not 966descriptors to non-blocking mode is also usually a good idea (but not
839required if you know what you are doing). 967required if you know what you are doing).
840.PP 968.PP
841You have to be careful with dup'ed file descriptors, though. Some backends 969You have to be careful with dup'ed file descriptors, though. Some backends
842(the linux epoll backend is a notable example) cannot handle dup'ed file 970(the linux epoll backend is a notable example) cannot handle dup'ed file
843descriptors correctly if you register interest in two or more fds pointing 971descriptors correctly if you register interest in two or more fds pointing
844to the same underlying file/socket etc. description (that is, they share 972to the same underlying file/socket/etc. description (that is, they share
845the same underlying \*(L"file open\*(R"). 973the same underlying \*(L"file open\*(R").
846.PP 974.PP
847If you must do this, then force the use of a known-to-be-good backend 975If you must do this, then force the use of a known-to-be-good backend
848(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and 976(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
849\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). 977\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
978.PP
979Another thing you have to watch out for is that it is quite easy to
980receive \*(L"spurious\*(R" readyness notifications, that is your callback might
981be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
982because there is no data. Not only are some backends known to create a
983lot of those (for example solaris ports), it is very easy to get into
984this situation even with a relatively standard program structure. Thus
985it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
986\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
987.PP
988If you cannot run the fd in non-blocking mode (for example you should not
989play around with an Xlib connection), then you have to seperately re-test
990wether a file descriptor is really ready with a known-to-be good interface
991such as poll (fortunately in our Xlib example, Xlib already does this on
992its own, so its quite safe to use).
850.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 993.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
851.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 994.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
852.PD 0 995.PD 0
853.IP "ev_io_set (ev_io *, int fd, int events)" 4 996.IP "ev_io_set (ev_io *, int fd, int events)" 4
854.IX Item "ev_io_set (ev_io *, int fd, int events)" 997.IX Item "ev_io_set (ev_io *, int fd, int events)"
855.PD 998.PD
856Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 999Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
857events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | 1000rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
858EV_WRITE\*(C'\fR to receive the given events. 1001\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
859.Sp 1002.IP "int fd [read\-only]" 4
860Please note that most of the more scalable backend mechanisms (for example 1003.IX Item "int fd [read-only]"
861epoll and solaris ports) can result in spurious readyness notifications 1004The file descriptor being watched.
862for file descriptors, so you practically need to use non-blocking I/O (and 1005.IP "int events [read\-only]" 4
863treat callback invocation as hint only), or retest separately with a safe 1006.IX Item "int events [read-only]"
864interface before doing I/O (XLib can do this), or force the use of either 1007The events being watched.
865\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
866problem. Also note that it is quite easy to have your callback invoked
867when the readyness condition is no longer valid even when employing
868typical ways of handling events, so its a good idea to use non-blocking
869I/O unconditionally.
870.PP 1008.PP
871Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1009Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
872readable, but only once. Since it is likely line\-buffered, you could 1010readable, but only once. Since it is likely line\-buffered, you could
873attempt to read a whole line in the callback: 1011attempt to read a whole line in the callback.
874.PP 1012.PP
875.Vb 6 1013.Vb 6
876\& static void 1014\& static void
877\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1015\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
878\& { 1016\& {
… …
887\& struct ev_io stdin_readable; 1025\& struct ev_io stdin_readable;
888\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1026\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
889\& ev_io_start (loop, &stdin_readable); 1027\& ev_io_start (loop, &stdin_readable);
890\& ev_loop (loop, 0); 1028\& ev_loop (loop, 0);
891.Ve 1029.Ve
892.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 1030.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
893.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 1031.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
894.IX Subsection "ev_timer - relative and optionally recurring timeouts" 1032.IX Subsection "ev_timer - relative and optionally repeating timeouts"
895Timer watchers are simple relative timers that generate an event after a 1033Timer watchers are simple relative timers that generate an event after a
896given time, and optionally repeating in regular intervals after that. 1034given time, and optionally repeating in regular intervals after that.
897.PP 1035.PP
898The timers are based on real time, that is, if you register an event that 1036The timers are based on real time, that is, if you register an event that
899times out after an hour and you reset your system clock to last years 1037times out after an hour and you reset your system clock to last years
… …
939.Sp 1077.Sp
940If the timer is repeating, either start it if necessary (with the repeat 1078If the timer is repeating, either start it if necessary (with the repeat
941value), or reset the running timer to the repeat value. 1079value), or reset the running timer to the repeat value.
942.Sp 1080.Sp
943This sounds a bit complicated, but here is a useful and typical 1081This sounds a bit complicated, but here is a useful and typical
944example: Imagine you have a tcp connection and you want a so-called idle 1082example: Imagine you have a tcp connection and you want a so-called
945timeout, that is, you want to be called when there have been, say, 60 1083idle timeout, that is, you want to be called when there have been,
946seconds of inactivity on the socket. The easiest way to do this is to 1084say, 60 seconds of inactivity on the socket. The easiest way to do
947configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each 1085this 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
948time you successfully read or write some data. If you go into an idle 1086\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
949state where you do not expect data to travel on the socket, you can stop 1087you go into an idle state where you do not expect data to travel on the
950the timer, and again will automatically restart it if need be. 1088socket, you can stop the timer, and again will automatically restart it if
1089need be.
1090.Sp
1091You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether
1092and only ever use the \f(CW\*(C`repeat\*(C'\fR value:
1093.Sp
1094.Vb 8
1095\& ev_timer_init (timer, callback, 0., 5.);
1096\& ev_timer_again (loop, timer);
1097\& ...
1098\& timer->again = 17.;
1099\& ev_timer_again (loop, timer);
1100\& ...
1101\& timer->again = 10.;
1102\& ev_timer_again (loop, timer);
1103.Ve
1104.Sp
1105This is more efficient then stopping/starting the timer eahc time you want
1106to modify its timeout value.
1107.IP "ev_tstamp repeat [read\-write]" 4
1108.IX Item "ev_tstamp repeat [read-write]"
1109The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1110or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1111which is also when any modifications are taken into account.
951.PP 1112.PP
952Example: create a timer that fires after 60 seconds. 1113Example: Create a timer that fires after 60 seconds.
953.PP 1114.PP
954.Vb 5 1115.Vb 5
955\& static void 1116\& static void
956\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1117\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
957\& { 1118\& {
… …
963\& struct ev_timer mytimer; 1124\& struct ev_timer mytimer;
964\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1125\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
965\& ev_timer_start (loop, &mytimer); 1126\& ev_timer_start (loop, &mytimer);
966.Ve 1127.Ve
967.PP 1128.PP
968Example: create a timeout timer that times out after 10 seconds of 1129Example: Create a timeout timer that times out after 10 seconds of
969inactivity. 1130inactivity.
970.PP 1131.PP
971.Vb 5 1132.Vb 5
972\& static void 1133\& static void
973\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1134\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
986.Vb 3 1147.Vb 3
987\& // and in some piece of code that gets executed on any "activity": 1148\& // and in some piece of code that gets executed on any "activity":
988\& // reset the timeout to start ticking again at 10 seconds 1149\& // reset the timeout to start ticking again at 10 seconds
989\& ev_timer_again (&mytimer); 1150\& ev_timer_again (&mytimer);
990.Ve 1151.Ve
991.ie n .Sh """ev_periodic"" \- to cron or not to cron" 1152.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
992.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 1153.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
993.IX Subsection "ev_periodic - to cron or not to cron" 1154.IX Subsection "ev_periodic - to cron or not to cron?"
994Periodic watchers are also timers of a kind, but they are very versatile 1155Periodic watchers are also timers of a kind, but they are very versatile
995(and unfortunately a bit complex). 1156(and unfortunately a bit complex).
996.PP 1157.PP
997Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1158Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
998but on wallclock time (absolute time). You can tell a periodic watcher 1159but on wallclock time (absolute time). You can tell a periodic watcher
… …
1087.IX Item "ev_periodic_again (loop, ev_periodic *)" 1248.IX Item "ev_periodic_again (loop, ev_periodic *)"
1088Simply stops and restarts the periodic watcher again. This is only useful 1249Simply stops and restarts the periodic watcher again. This is only useful
1089when you changed some parameters or the reschedule callback would return 1250when you changed some parameters or the reschedule callback would return
1090a different time than the last time it was called (e.g. in a crond like 1251a different time than the last time it was called (e.g. in a crond like
1091program when the crontabs have changed). 1252program when the crontabs have changed).
1253.IP "ev_tstamp interval [read\-write]" 4
1254.IX Item "ev_tstamp interval [read-write]"
1255The current interval value. Can be modified any time, but changes only
1256take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1257called.
1258.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1259.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1260The current reschedule callback, or \f(CW0\fR, if this functionality is
1261switched off. Can be changed any time, but changes only take effect when
1262the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1092.PP 1263.PP
1093Example: call a callback every hour, or, more precisely, whenever the 1264Example: Call a callback every hour, or, more precisely, whenever the
1094system clock is divisible by 3600. The callback invocation times have 1265system clock is divisible by 3600. The callback invocation times have
1095potentially a lot of jittering, but good long-term stability. 1266potentially a lot of jittering, but good long-term stability.
1096.PP 1267.PP
1097.Vb 5 1268.Vb 5
1098\& static void 1269\& static void
… …
1106\& struct ev_periodic hourly_tick; 1277\& struct ev_periodic hourly_tick;
1107\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1278\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1108\& ev_periodic_start (loop, &hourly_tick); 1279\& ev_periodic_start (loop, &hourly_tick);
1109.Ve 1280.Ve
1110.PP 1281.PP
1111Example: the same as above, but use a reschedule callback to do it: 1282Example: The same as above, but use a reschedule callback to do it:
1112.PP 1283.PP
1113.Vb 1 1284.Vb 1
1114\& #include <math.h> 1285\& #include <math.h>
1115.Ve 1286.Ve
1116.PP 1287.PP
… …
1124.PP 1295.PP
1125.Vb 1 1296.Vb 1
1126\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1297\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1127.Ve 1298.Ve
1128.PP 1299.PP
1129Example: call a callback every hour, starting now: 1300Example: Call a callback every hour, starting now:
1130.PP 1301.PP
1131.Vb 4 1302.Vb 4
1132\& struct ev_periodic hourly_tick; 1303\& struct ev_periodic hourly_tick;
1133\& ev_periodic_init (&hourly_tick, clock_cb, 1304\& ev_periodic_init (&hourly_tick, clock_cb,
1134\& fmod (ev_now (loop), 3600.), 3600., 0); 1305\& fmod (ev_now (loop), 3600.), 3600., 0);
1135\& ev_periodic_start (loop, &hourly_tick); 1306\& ev_periodic_start (loop, &hourly_tick);
1136.Ve 1307.Ve
1137.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1308.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1138.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" 1309.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1139.IX Subsection "ev_signal - signal me when a signal gets signalled" 1310.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1140Signal watchers will trigger an event when the process receives a specific 1311Signal watchers will trigger an event when the process receives a specific
1141signal one or more times. Even though signals are very asynchronous, libev 1312signal one or more times. Even though signals are very asynchronous, libev
1142will try it's best to deliver signals synchronously, i.e. as part of the 1313will try it's best to deliver signals synchronously, i.e. as part of the
1143normal event processing, like any other event. 1314normal event processing, like any other event.
1144.PP 1315.PP
… …
1154.IP "ev_signal_set (ev_signal *, int signum)" 4 1325.IP "ev_signal_set (ev_signal *, int signum)" 4
1155.IX Item "ev_signal_set (ev_signal *, int signum)" 1326.IX Item "ev_signal_set (ev_signal *, int signum)"
1156.PD 1327.PD
1157Configures the watcher to trigger on the given signal number (usually one 1328Configures the watcher to trigger on the given signal number (usually one
1158of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1329of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
1330.IP "int signum [read\-only]" 4
1331.IX Item "int signum [read-only]"
1332The signal the watcher watches out for.
1159.ie n .Sh """ev_child"" \- wait for pid status changes" 1333.ie n .Sh """ev_child"" \- watch out for process status changes"
1160.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1334.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1161.IX Subsection "ev_child - wait for pid status changes" 1335.IX Subsection "ev_child - watch out for process status changes"
1162Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1336Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1163some child status changes (most typically when a child of yours dies). 1337some child status changes (most typically when a child of yours dies).
1164.IP "ev_child_init (ev_child *, callback, int pid)" 4 1338.IP "ev_child_init (ev_child *, callback, int pid)" 4
1165.IX Item "ev_child_init (ev_child *, callback, int pid)" 1339.IX Item "ev_child_init (ev_child *, callback, int pid)"
1166.PD 0 1340.PD 0
… …
1171\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1345\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
1172at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see 1346at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
1173the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems 1347the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
1174\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the 1348\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
1175process causing the status change. 1349process causing the status change.
1350.IP "int pid [read\-only]" 4
1351.IX Item "int pid [read-only]"
1352The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
1353.IP "int rpid [read\-write]" 4
1354.IX Item "int rpid [read-write]"
1355The process id that detected a status change.
1356.IP "int rstatus [read\-write]" 4
1357.IX Item "int rstatus [read-write]"
1358The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1359\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1176.PP 1360.PP
1177Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1361Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1178.PP 1362.PP
1179.Vb 5 1363.Vb 5
1180\& static void 1364\& static void
1181\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1365\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1182\& { 1366\& {
… …
1187.Vb 3 1371.Vb 3
1188\& struct ev_signal signal_watcher; 1372\& struct ev_signal signal_watcher;
1189\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 1373\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1190\& ev_signal_start (loop, &sigint_cb); 1374\& ev_signal_start (loop, &sigint_cb);
1191.Ve 1375.Ve
1376.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1377.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1378.IX Subsection "ev_stat - did the file attributes just change?"
1379This watches a filesystem path for attribute changes. That is, it calls
1380\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1381compared to the last time, invoking the callback if it did.
1382.PP
1383The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1384not exist\*(R" is a status change like any other. The condition \*(L"path does
1385not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1386otherwise always forced to be at least one) and all the other fields of
1387the stat buffer having unspecified contents.
1388.PP
1389The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1390relative and your working directory changes, the behaviour is undefined.
1391.PP
1392Since there is no standard to do this, the portable implementation simply
1393calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1394can specify a recommended polling interval for this case. If you specify
1395a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1396unspecified default\fR value will be used (which you can expect to be around
1397five seconds, although this might change dynamically). Libev will also
1398impose a minimum interval which is currently around \f(CW0.1\fR, but thats
1399usually overkill.
1400.PP
1401This watcher type is not meant for massive numbers of stat watchers,
1402as even with OS-supported change notifications, this can be
1403resource\-intensive.
1404.PP
1405At the time of this writing, only the Linux inotify interface is
1406implemented (implementing kqueue support is left as an exercise for the
1407reader). Inotify will be used to give hints only and should not change the
1408semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1409to fall back to regular polling again even with inotify, but changes are
1410usually detected immediately, and if the file exists there will be no
1411polling.
1412.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1413.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1414.PD 0
1415.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1416.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
1417.PD
1418Configures the watcher to wait for status changes of the given
1419\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
1420be detected and should normally be specified as \f(CW0\fR to let libev choose
1421a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
1422path for as long as the watcher is active.
1423.Sp
1424The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
1425relative to the attributes at the time the watcher was started (or the
1426last change was detected).
1427.IP "ev_stat_stat (ev_stat *)" 4
1428.IX Item "ev_stat_stat (ev_stat *)"
1429Updates the stat buffer immediately with new values. If you change the
1430watched path in your callback, you could call this fucntion to avoid
1431detecting this change (while introducing a race condition). Can also be
1432useful simply to find out the new values.
1433.IP "ev_statdata attr [read\-only]" 4
1434.IX Item "ev_statdata attr [read-only]"
1435The most-recently detected attributes of the file. Although the type is of
1436\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
1437suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
1438was some error while \f(CW\*(C`stat\*(C'\fRing the file.
1439.IP "ev_statdata prev [read\-only]" 4
1440.IX Item "ev_statdata prev [read-only]"
1441The previous attributes of the file. The callback gets invoked whenever
1442\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
1443.IP "ev_tstamp interval [read\-only]" 4
1444.IX Item "ev_tstamp interval [read-only]"
1445The specified interval.
1446.IP "const char *path [read\-only]" 4
1447.IX Item "const char *path [read-only]"
1448The filesystem path that is being watched.
1449.PP
1450Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1451.PP
1452.Vb 15
1453\& static void
1454\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1455\& {
1456\& /* /etc/passwd changed in some way */
1457\& if (w->attr.st_nlink)
1458\& {
1459\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
1460\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
1461\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
1462\& }
1463\& else
1464\& /* you shalt not abuse printf for puts */
1465\& puts ("wow, /etc/passwd is not there, expect problems. "
1466\& "if this is windows, they already arrived\en");
1467\& }
1468.Ve
1469.PP
1470.Vb 2
1471\& ...
1472\& ev_stat passwd;
1473.Ve
1474.PP
1475.Vb 2
1476\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
1477\& ev_stat_start (loop, &passwd);
1478.Ve
1192.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1479.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1193.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" 1480.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1194.IX Subsection "ev_idle - when you've got nothing better to do" 1481.IX Subsection "ev_idle - when you've got nothing better to do..."
1195Idle watchers trigger events when there are no other events are pending 1482Idle watchers trigger events when there are no other events are pending
1196(prepare, check and other idle watchers do not count). That is, as long 1483(prepare, check and other idle watchers do not count). That is, as long
1197as your process is busy handling sockets or timeouts (or even signals, 1484as your process is busy handling sockets or timeouts (or even signals,
1198imagine) it will not be triggered. But when your process is idle all idle 1485imagine) it will not be triggered. But when your process is idle all idle
1199watchers are being called again and again, once per event loop iteration \- 1486watchers are being called again and again, once per event loop iteration \-
… …
1211.IX Item "ev_idle_init (ev_signal *, callback)" 1498.IX Item "ev_idle_init (ev_signal *, callback)"
1212Initialises and configures the idle watcher \- it has no parameters of any 1499Initialises and configures the idle watcher \- it has no parameters of any
1213kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1500kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1214believe me. 1501believe me.
1215.PP 1502.PP
1216Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1503Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1217callback, free it. Alos, use no error checking, as usual. 1504callback, free it. Also, use no error checking, as usual.
1218.PP 1505.PP
1219.Vb 7 1506.Vb 7
1220\& static void 1507\& static void
1221\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1508\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1222\& { 1509\& {
… …
1229.Vb 3 1516.Vb 3
1230\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 1517\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1231\& ev_idle_init (idle_watcher, idle_cb); 1518\& ev_idle_init (idle_watcher, idle_cb);
1232\& ev_idle_start (loop, idle_cb); 1519\& ev_idle_start (loop, idle_cb);
1233.Ve 1520.Ve
1234.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1521.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1235.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" 1522.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1236.IX Subsection "ev_prepare and ev_check - customise your event loop" 1523.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1237Prepare and check watchers are usually (but not always) used in tandem: 1524Prepare and check watchers are usually (but not always) used in tandem:
1238prepare watchers get invoked before the process blocks and check watchers 1525prepare watchers get invoked before the process blocks and check watchers
1239afterwards. 1526afterwards.
1240.PP 1527.PP
1528You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1529the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1530watchers. Other loops than the current one are fine, however. The
1531rationale behind this is that you do not need to check for recursion in
1532those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1533\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1534called in pairs bracketing the blocking call.
1535.PP
1241Their main purpose is to integrate other event mechanisms into libev and 1536Their main purpose is to integrate other event mechanisms into libev and
1242their use is somewhat advanced. This could be used, for example, to track 1537their use is somewhat advanced. This could be used, for example, to track
1243variable changes, implement your own watchers, integrate net-snmp or a 1538variable changes, implement your own watchers, integrate net-snmp or a
1244coroutine library and lots more. 1539coroutine library and lots more. They are also occasionally useful if
1540you cache some data and want to flush it before blocking (for example,
1541in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1542watcher).
1245.PP 1543.PP
1246This is done by examining in each prepare call which file descriptors need 1544This is done by examining in each prepare call which file descriptors need
1247to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 1545to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1248them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 1546them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1249provide just this functionality). Then, in the check watcher you check for 1547provide just this functionality). Then, in the check watcher you check for
… …
1268.PD 1566.PD
1269Initialises and configures the prepare or check watcher \- they have no 1567Initialises and configures the prepare or check watcher \- they have no
1270parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1568parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1271macros, but using them is utterly, utterly and completely pointless. 1569macros, but using them is utterly, utterly and completely pointless.
1272.PP 1570.PP
1273Example: *TODO*. 1571Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1572and a timeout watcher in a prepare handler, as required by libadns, and
1573in a check watcher, destroy them and call into libadns. What follows is
1574pseudo-code only of course:
1575.PP
1576.Vb 2
1577\& static ev_io iow [nfd];
1578\& static ev_timer tw;
1579.Ve
1580.PP
1581.Vb 9
1582\& static void
1583\& io_cb (ev_loop *loop, ev_io *w, int revents)
1584\& {
1585\& // set the relevant poll flags
1586\& // could also call adns_processreadable etc. here
1587\& struct pollfd *fd = (struct pollfd *)w->data;
1588\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1589\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1590\& }
1591.Ve
1592.PP
1593.Vb 7
1594\& // create io watchers for each fd and a timer before blocking
1595\& static void
1596\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1597\& {
1598\& int timeout = 3600000;truct pollfd fds [nfd];
1599\& // actual code will need to loop here and realloc etc.
1600\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1601.Ve
1602.PP
1603.Vb 3
1604\& /* the callback is illegal, but won't be called as we stop during check */
1605\& ev_timer_init (&tw, 0, timeout * 1e-3);
1606\& ev_timer_start (loop, &tw);
1607.Ve
1608.PP
1609.Vb 6
1610\& // create on ev_io per pollfd
1611\& for (int i = 0; i < nfd; ++i)
1612\& {
1613\& ev_io_init (iow + i, io_cb, fds [i].fd,
1614\& ((fds [i].events & POLLIN ? EV_READ : 0)
1615\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1616.Ve
1617.PP
1618.Vb 5
1619\& fds [i].revents = 0;
1620\& iow [i].data = fds + i;
1621\& ev_io_start (loop, iow + i);
1622\& }
1623\& }
1624.Ve
1625.PP
1626.Vb 5
1627\& // stop all watchers after blocking
1628\& static void
1629\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1630\& {
1631\& ev_timer_stop (loop, &tw);
1632.Ve
1633.PP
1634.Vb 2
1635\& for (int i = 0; i < nfd; ++i)
1636\& ev_io_stop (loop, iow + i);
1637.Ve
1638.PP
1639.Vb 2
1640\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1641\& }
1642.Ve
1274.ie n .Sh """ev_embed"" \- when one backend isn't enough" 1643.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1275.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough" 1644.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1276.IX Subsection "ev_embed - when one backend isn't enough" 1645.IX Subsection "ev_embed - when one backend isn't enough..."
1277This is a rather advanced watcher type that lets you embed one event loop 1646This is a rather advanced watcher type that lets you embed one event loop
1278into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded 1647into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1279loop, other types of watchers might be handled in a delayed or incorrect 1648loop, other types of watchers might be handled in a delayed or incorrect
1280fashion and must not be used). 1649fashion and must not be used).
1281.PP 1650.PP
… …
1361.IP "ev_embed_sweep (loop, ev_embed *)" 4 1730.IP "ev_embed_sweep (loop, ev_embed *)" 4
1362.IX Item "ev_embed_sweep (loop, ev_embed *)" 1731.IX Item "ev_embed_sweep (loop, ev_embed *)"
1363Make a single, non-blocking sweep over the embedded loop. This works 1732Make a single, non-blocking sweep over the embedded loop. This works
1364similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 1733similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1365apropriate way for embedded loops. 1734apropriate way for embedded loops.
1735.IP "struct ev_loop *loop [read\-only]" 4
1736.IX Item "struct ev_loop *loop [read-only]"
1737The embedded event loop.
1738.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1739.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1740.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1741Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
1742whoever is a good citizen cared to tell libev about it by calling
1743\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1744event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1745and only in the child after the fork. If whoever good citizen calling
1746\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1747handlers will be invoked, too, of course.
1748.IP "ev_fork_init (ev_signal *, callback)" 4
1749.IX Item "ev_fork_init (ev_signal *, callback)"
1750Initialises and configures the fork watcher \- it has no parameters of any
1751kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1752believe me.
1366.SH "OTHER FUNCTIONS" 1753.SH "OTHER FUNCTIONS"
1367.IX Header "OTHER FUNCTIONS" 1754.IX Header "OTHER FUNCTIONS"
1368There are some other functions of possible interest. Described. Here. Now. 1755There are some other functions of possible interest. Described. Here. Now.
1369.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1756.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
1370.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 1757.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
1509\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 1896\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1510.ie n .IP "w\->sweep () ""ev::embed"" only" 4 1897.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1511.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 1898.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1512.IX Item "w->sweep () ev::embed only" 1899.IX Item "w->sweep () ev::embed only"
1513Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 1900Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1901.ie n .IP "w\->update () ""ev::stat"" only" 4
1902.el .IP "w\->update () \f(CWev::stat\fR only" 4
1903.IX Item "w->update () ev::stat only"
1904Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1514.RE 1905.RE
1515.RS 4 1906.RS 4
1516.RE 1907.RE
1517.PP 1908.PP
1518Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in 1909Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
… …
1535\& : io (this, &myclass::io_cb), 1926\& : io (this, &myclass::io_cb),
1536\& idle (this, &myclass::idle_cb) 1927\& idle (this, &myclass::idle_cb)
1537\& { 1928\& {
1538\& io.start (fd, ev::READ); 1929\& io.start (fd, ev::READ);
1539\& } 1930\& }
1931.Ve
1932.SH "MACRO MAGIC"
1933.IX Header "MACRO MAGIC"
1934Libev can be compiled with a variety of options, the most fundemantal is
1935\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and
1936callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1937.PP
1938To make it easier to write programs that cope with either variant, the
1939following macros are defined:
1940.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1941.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
1942.IX Item "EV_A, EV_A_"
1943This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
1944loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
1945\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
1946.Sp
1947.Vb 3
1948\& ev_unref (EV_A);
1949\& ev_timer_add (EV_A_ watcher);
1950\& ev_loop (EV_A_ 0);
1951.Ve
1952.Sp
1953It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
1954which is often provided by the following macro.
1955.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
1956.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
1957.IX Item "EV_P, EV_P_"
1958This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
1959loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
1960\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
1961.Sp
1962.Vb 2
1963\& // this is how ev_unref is being declared
1964\& static void ev_unref (EV_P);
1965.Ve
1966.Sp
1967.Vb 2
1968\& // this is how you can declare your typical callback
1969\& static void cb (EV_P_ ev_timer *w, int revents)
1970.Ve
1971.Sp
1972It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
1973suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
1974.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
1975.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1976.IX Item "EV_DEFAULT, EV_DEFAULT_"
1977Similar to the other two macros, this gives you the value of the default
1978loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1979.PP
1980Example: Declare and initialise a check watcher, working regardless of
1981wether multiple loops are supported or not.
1982.PP
1983.Vb 5
1984\& static void
1985\& check_cb (EV_P_ ev_timer *w, int revents)
1986\& {
1987\& ev_check_stop (EV_A_ w);
1988\& }
1989.Ve
1990.PP
1991.Vb 4
1992\& ev_check check;
1993\& ev_check_init (&check, check_cb);
1994\& ev_check_start (EV_DEFAULT_ &check);
1995\& ev_loop (EV_DEFAULT_ 0);
1540.Ve 1996.Ve
1541.SH "EMBEDDING" 1997.SH "EMBEDDING"
1542.IX Header "EMBEDDING" 1998.IX Header "EMBEDDING"
1543Libev can (and often is) directly embedded into host 1999Libev can (and often is) directly embedded into host
1544applications. Examples of applications that embed it include the Deliantra 2000applications. Examples of applications that embed it include the Deliantra
… …
1593.Vb 1 2049.Vb 1
1594\& ev_win32.c required on win32 platforms only 2050\& ev_win32.c required on win32 platforms only
1595.Ve 2051.Ve
1596.PP 2052.PP
1597.Vb 5 2053.Vb 5
1598\& ev_select.c only when select backend is enabled (which is is by default) 2054\& ev_select.c only when select backend is enabled (which is by default)
1599\& ev_poll.c only when poll backend is enabled (disabled by default) 2055\& ev_poll.c only when poll backend is enabled (disabled by default)
1600\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2056\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
1601\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2057\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1602\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2058\& ev_port.c only when the solaris port backend is enabled (disabled by default)
1603.Ve 2059.Ve
1604.PP 2060.PP
1605\&\fIev.c\fR includes the backend files directly when enabled, so you only need 2061\&\fIev.c\fR includes the backend files directly when enabled, so you only need
1606to compile a single file. 2062to compile this single file.
1607.PP 2063.PP
1608\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR 2064\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
1609.IX Subsection "LIBEVENT COMPATIBILITY API" 2065.IX Subsection "LIBEVENT COMPATIBILITY API"
1610.PP 2066.PP
1611To include the libevent compatibility \s-1API\s0, also include: 2067To include the libevent compatibility \s-1API\s0, also include:
… …
1632\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 2088\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
1633.IX Subsection "AUTOCONF SUPPORT" 2089.IX Subsection "AUTOCONF SUPPORT"
1634.PP 2090.PP
1635Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in 2091Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
1636whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 2092whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
1637\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR off. \fIev.c\fR will then include 2093\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
1638\&\fIconfig.h\fR and configure itself accordingly. 2094include \fIconfig.h\fR and configure itself accordingly.
1639.PP 2095.PP
1640For this of course you need the m4 file: 2096For this of course you need the m4 file:
1641.PP 2097.PP
1642.Vb 1 2098.Vb 1
1643\& libev.m4 2099\& libev.m4
… …
1713otherwise another method will be used as fallback. This is the preferred 2169otherwise another method will be used as fallback. This is the preferred
1714backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only 2170backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
1715supports some types of fds correctly (the only platform we found that 2171supports some types of fds correctly (the only platform we found that
1716supports ptys for example was NetBSD), so kqueue might be compiled in, but 2172supports ptys for example was NetBSD), so kqueue might be compiled in, but
1717not be used unless explicitly requested. The best way to use it is to find 2173not be used unless explicitly requested. The best way to use it is to find
1718out wether kqueue supports your type of fd properly and use an embedded 2174out whether kqueue supports your type of fd properly and use an embedded
1719kqueue loop. 2175kqueue loop.
1720.IP "\s-1EV_USE_PORT\s0" 4 2176.IP "\s-1EV_USE_PORT\s0" 4
1721.IX Item "EV_USE_PORT" 2177.IX Item "EV_USE_PORT"
1722If defined to be \f(CW1\fR, libev will compile in support for the Solaris 2178If defined to be \f(CW1\fR, libev will compile in support for the Solaris
172310 port style backend. Its availability will be detected at runtime, 217910 port style backend. Its availability will be detected at runtime,
1724otherwise another method will be used as fallback. This is the preferred 2180otherwise another method will be used as fallback. This is the preferred
1725backend for Solaris 10 systems. 2181backend for Solaris 10 systems.
1726.IP "\s-1EV_USE_DEVPOLL\s0" 4 2182.IP "\s-1EV_USE_DEVPOLL\s0" 4
1727.IX Item "EV_USE_DEVPOLL" 2183.IX Item "EV_USE_DEVPOLL"
1728reserved for future expansion, works like the \s-1USE\s0 symbols above. 2184reserved for future expansion, works like the \s-1USE\s0 symbols above.
2185.IP "\s-1EV_USE_INOTIFY\s0" 4
2186.IX Item "EV_USE_INOTIFY"
2187If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2188interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2189be detected at runtime.
1729.IP "\s-1EV_H\s0" 4 2190.IP "\s-1EV_H\s0" 4
1730.IX Item "EV_H" 2191.IX Item "EV_H"
1731The name of the \fIev.h\fR header file used to include it. The default if 2192The name of the \fIev.h\fR header file used to include it. The default if
1732undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2193undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
1733can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2194can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
1751If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2212If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
1752will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2213will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
1753additional independent event loops. Otherwise there will be no support 2214additional independent event loops. Otherwise there will be no support
1754for multiple event loops and there is no first event loop pointer 2215for multiple event loops and there is no first event loop pointer
1755argument. Instead, all functions act on the single default loop. 2216argument. Instead, all functions act on the single default loop.
1756.IP "\s-1EV_PERIODICS\s0" 4 2217.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
1757.IX Item "EV_PERIODICS" 2218.IX Item "EV_PERIODIC_ENABLE"
1758If undefined or defined to be \f(CW1\fR, then periodic timers are supported, 2219If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
1759otherwise not. This saves a few kb of code. 2220defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2221code.
2222.IP "\s-1EV_EMBED_ENABLE\s0" 4
2223.IX Item "EV_EMBED_ENABLE"
2224If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
2225defined to be \f(CW0\fR, then they are not.
2226.IP "\s-1EV_STAT_ENABLE\s0" 4
2227.IX Item "EV_STAT_ENABLE"
2228If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
2229defined to be \f(CW0\fR, then they are not.
2230.IP "\s-1EV_FORK_ENABLE\s0" 4
2231.IX Item "EV_FORK_ENABLE"
2232If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
2233defined to be \f(CW0\fR, then they are not.
2234.IP "\s-1EV_MINIMAL\s0" 4
2235.IX Item "EV_MINIMAL"
2236If you need to shave off some kilobytes of code at the expense of some
2237speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
2238some inlining decisions, saves roughly 30% codesize of amd64.
2239.IP "\s-1EV_PID_HASHSIZE\s0" 4
2240.IX Item "EV_PID_HASHSIZE"
2241\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2242pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2243than enough. If you need to manage thousands of children you might want to
2244increase this value (\fImust\fR be a power of two).
2245.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2246.IX Item "EV_INOTIFY_HASHSIZE"
2247\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2248inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2249usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2250watchers you might want to increase this value (\fImust\fR be a power of
2251two).
1760.IP "\s-1EV_COMMON\s0" 4 2252.IP "\s-1EV_COMMON\s0" 4
1761.IX Item "EV_COMMON" 2253.IX Item "EV_COMMON"
1762By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2254By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
1763this macro to a something else you can include more and other types of 2255this macro to a something else you can include more and other types of
1764members. You have to define it each time you include one of the files, 2256members. You have to define it each time you include one of the files,
… …
1769.Vb 3 2261.Vb 3
1770\& #define EV_COMMON \e 2262\& #define EV_COMMON \e
1771\& SV *self; /* contains this struct */ \e 2263\& SV *self; /* contains this struct */ \e
1772\& SV *cb_sv, *fh /* note no trailing ";" */ 2264\& SV *cb_sv, *fh /* note no trailing ";" */
1773.Ve 2265.Ve
1774.IP "\s-1EV_CB_DECLARE\s0(type)" 4 2266.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
1775.IX Item "EV_CB_DECLARE(type)" 2267.IX Item "EV_CB_DECLARE (type)"
1776.PD 0 2268.PD 0
1777.IP "\s-1EV_CB_INVOKE\s0(watcher,revents)" 4 2269.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
1778.IX Item "EV_CB_INVOKE(watcher,revents)" 2270.IX Item "EV_CB_INVOKE (watcher, revents)"
1779.IP "ev_set_cb(ev,cb)" 4 2271.IP "ev_set_cb (ev, cb)" 4
1780.IX Item "ev_set_cb(ev,cb)" 2272.IX Item "ev_set_cb (ev, cb)"
1781.PD 2273.PD
1782Can be used to change the callback member declaration in each watcher, 2274Can be used to change the callback member declaration in each watcher,
1783and the way callbacks are invoked and set. Must expand to a struct member 2275and the way callbacks are invoked and set. Must expand to a struct member
1784definition and a statement, respectively. See the \fIev.v\fR header file for 2276definition and a statement, respectively. See the \fIev.v\fR header file for
1785their default definitions. One possible use for overriding these is to 2277their default definitions. One possible use for overriding these is to
1786avoid the ev_loop pointer as first argument in all cases, or to use method 2278avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
1787calls instead of plain function calls in \*(C+. 2279method calls instead of plain function calls in \*(C+.
1788.Sh "\s-1EXAMPLES\s0" 2280.Sh "\s-1EXAMPLES\s0"
1789.IX Subsection "EXAMPLES" 2281.IX Subsection "EXAMPLES"
1790For a real-world example of a program the includes libev 2282For a real-world example of a program the includes libev
1791verbatim, you can have a look at the \s-1EV\s0 perl module 2283verbatim, you can have a look at the \s-1EV\s0 perl module
1792(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2284(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
… …
1797.Sp 2289.Sp
1798The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2290The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
1799that everybody includes and which overrides some autoconf choices: 2291that everybody includes and which overrides some autoconf choices:
1800.Sp 2292.Sp
1801.Vb 4 2293.Vb 4
1802\& #define EV_USE_POLL 0 2294\& #define EV_USE_POLL 0
1803\& #define EV_MULTIPLICITY 0 2295\& #define EV_MULTIPLICITY 0
1804\& #define EV_PERIODICS 0 2296\& #define EV_PERIODICS 0
1805\& #define EV_CONFIG_H <config.h> 2297\& #define EV_CONFIG_H <config.h>
1806.Ve 2298.Ve
1807.Sp 2299.Sp
1808.Vb 1 2300.Vb 1
1809\& #include "ev++.h" 2301\& #include "ev++.h"
1810.Ve 2302.Ve
1811.Sp 2303.Sp
1812And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: 2304And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
1813.Sp 2305.Sp
1814.Vb 1
1815\& #include "rxvttoolkit.h"
1816.Ve
1817.Sp
1818.Vb 2 2306.Vb 2
1819\& /* darwin has problems with its header files in C++, requiring this namespace juggling */ 2307\& #include "ev_cpp.h"
1820\& using namespace ev;
1821.Ve
1822.Sp
1823.Vb 1
1824\& #include "ev.c" 2308\& #include "ev.c"
1825.Ve 2309.Ve
2310.SH "COMPLEXITIES"
2311.IX Header "COMPLEXITIES"
2312In this section the complexities of (many of) the algorithms used inside
2313libev will be explained. For complexity discussions about backends see the
2314documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2315.RS 4
2316.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2317.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2318.PD 0
2319.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2320.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2321.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2322.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2323.IP "Stopping check/prepare/idle watchers: O(1)" 4
2324.IX Item "Stopping check/prepare/idle watchers: O(1)"
2325.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2326.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2327.IP "Finding the next timer per loop iteration: O(1)" 4
2328.IX Item "Finding the next timer per loop iteration: O(1)"
2329.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2330.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2331.IP "Activating one watcher: O(1)" 4
2332.IX Item "Activating one watcher: O(1)"
2333.RE
2334.RS 4
2335.PD
1826.SH "AUTHOR" 2336.SH "AUTHOR"
1827.IX Header "AUTHOR" 2337.IX Header "AUTHOR"
1828Marc Lehmann <libev@schmorp.de>. 2338Marc Lehmann <libev@schmorp.de>.

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