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Revision 1.11 by root, Sat Nov 24 07:14:26 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 "2007-11-24" "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
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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));
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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
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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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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,
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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");
459.Ve 545.Ve
460.IP "ev_default_destroy ()" 4 546.IP "ev_default_destroy ()" 4
461.IX Item "ev_default_destroy ()" 547.IX Item "ev_default_destroy ()"
462Destroys the default loop again (frees all memory and kernel state 548Destroys the default loop again (frees all memory and kernel state
463etc.). This stops all registered event watchers (by not touching them in 549etc.). None of the active event watchers will be stopped in the normal
464any way whatsoever, although you cannot rely on this :). 550sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
551responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
552calling this function, or cope with the fact afterwards (which is usually
553the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
554for example).
465.IP "ev_loop_destroy (loop)" 4 555.IP "ev_loop_destroy (loop)" 4
466.IX Item "ev_loop_destroy (loop)" 556.IX Item "ev_loop_destroy (loop)"
467Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 557Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
468earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 558earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
469.IP "ev_default_fork ()" 4 559.IP "ev_default_fork ()" 4
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552\& be handled here by queueing them when their watcher gets executed. 642\& be handled here by queueing them when their watcher gets executed.
553\& - 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
554\& were used, return, otherwise continue with step *. 644\& were used, return, otherwise continue with step *.
555.Ve 645.Ve
556.Sp 646.Sp
557Example: queue some jobs and then loop until no events are outsanding 647Example: Queue some jobs and then loop until no events are outsanding
558anymore. 648anymore.
559.Sp 649.Sp
560.Vb 4 650.Vb 4
561\& ... queue jobs here, make sure they register event watchers as long 651\& ... queue jobs here, make sure they register event watchers as long
562\& ... 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..)
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584visible 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
585no 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
586way 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
587libraries. 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.
588.Sp 678.Sp
589Example: 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
590running when nothing else is active. 680running when nothing else is active.
591.Sp 681.Sp
592.Vb 4 682.Vb 4
593\& struct dv_signal exitsig; 683\& struct ev_signal exitsig;
594\& ev_signal_init (&exitsig, sig_cb, SIGINT); 684\& ev_signal_init (&exitsig, sig_cb, SIGINT);
595\& ev_signal_start (myloop, &exitsig); 685\& ev_signal_start (loop, &exitsig);
596\& evf_unref (myloop); 686\& evf_unref (loop);
597.Ve 687.Ve
598.Sp 688.Sp
599Example: for some weird reason, unregister the above signal handler again. 689Example: For some weird reason, unregister the above signal handler again.
600.Sp 690.Sp
601.Vb 2 691.Vb 2
602\& ev_ref (myloop); 692\& ev_ref (loop);
603\& ev_signal_stop (myloop, &exitsig); 693\& ev_signal_stop (loop, &exitsig);
604.Ve 694.Ve
605.SH "ANATOMY OF A WATCHER" 695.SH "ANATOMY OF A WATCHER"
606.IX Header "ANATOMY OF A WATCHER" 696.IX Header "ANATOMY OF A WATCHER"
607A 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
608interest 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
… …
680The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. 770The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread.
681.ie n .IP """EV_CHILD""" 4 771.ie n .IP """EV_CHILD""" 4
682.el .IP "\f(CWEV_CHILD\fR" 4 772.el .IP "\f(CWEV_CHILD\fR" 4
683.IX Item "EV_CHILD" 773.IX Item "EV_CHILD"
684The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. 774The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change.
775.ie n .IP """EV_STAT""" 4
776.el .IP "\f(CWEV_STAT\fR" 4
777.IX Item "EV_STAT"
778The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow.
685.ie n .IP """EV_IDLE""" 4 779.ie n .IP """EV_IDLE""" 4
686.el .IP "\f(CWEV_IDLE\fR" 4 780.el .IP "\f(CWEV_IDLE\fR" 4
687.IX Item "EV_IDLE" 781.IX Item "EV_IDLE"
688The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. 782The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do.
689.ie n .IP """EV_PREPARE""" 4 783.ie n .IP """EV_PREPARE""" 4
… …
699\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any 793\&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any
700received events. Callbacks of both watcher types can start and stop as 794received events. Callbacks of both watcher types can start and stop as
701many watchers as they want, and all of them will be taken into account 795many watchers as they want, and all of them will be taken into account
702(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep 796(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep
703\&\f(CW\*(C`ev_loop\*(C'\fR from blocking). 797\&\f(CW\*(C`ev_loop\*(C'\fR from blocking).
798.ie n .IP """EV_EMBED""" 4
799.el .IP "\f(CWEV_EMBED\fR" 4
800.IX Item "EV_EMBED"
801The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
802.ie n .IP """EV_FORK""" 4
803.el .IP "\f(CWEV_FORK\fR" 4
804.IX Item "EV_FORK"
805The event loop has been resumed in the child process after fork (see
806\&\f(CW\*(C`ev_fork\*(C'\fR).
704.ie n .IP """EV_ERROR""" 4 807.ie n .IP """EV_ERROR""" 4
705.el .IP "\f(CWEV_ERROR\fR" 4 808.el .IP "\f(CWEV_ERROR\fR" 4
706.IX Item "EV_ERROR" 809.IX Item "EV_ERROR"
707An unspecified error has occured, the watcher has been stopped. This might 810An unspecified error has occured, the watcher has been stopped. This might
708happen because the watcher could not be properly started because libev 811happen because the watcher could not be properly started because libev
… …
713Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 816Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
714for example it might indicate that a fd is readable or writable, and if 817for example it might indicate that a fd is readable or writable, and if
715your callbacks is well-written it can just attempt the operation and cope 818your callbacks is well-written it can just attempt the operation and cope
716with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 819with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
717programs, though, so beware. 820programs, though, so beware.
718.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 821.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
719.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS" 822.IX Subsection "GENERIC WATCHER FUNCTIONS"
720In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, 823In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
721e.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. 824e.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.
722.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 825.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
723.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 826.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
724.IX Item "ev_init (ev_TYPE *watcher, callback)" 827.IX Item "ev_init (ev_TYPE *watcher, callback)"
… …
730which rolls both calls into one. 833which rolls both calls into one.
731.Sp 834.Sp
732You can reinitialise a watcher at any time as long as it has been stopped 835You can reinitialise a watcher at any time as long as it has been stopped
733(or never started) and there are no pending events outstanding. 836(or never started) and there are no pending events outstanding.
734.Sp 837.Sp
735The callbakc is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, 838The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher,
736int revents)\*(C'\fR. 839int revents)\*(C'\fR.
737.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 840.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
738.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 841.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
739.IX Item "ev_TYPE_set (ev_TYPE *, [args])" 842.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
740This macro initialises the type-specific parts of a watcher. You need to 843This macro initialises the type-specific parts of a watcher. You need to
… …
775Returns 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
776events 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
777is 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
778\&\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
779libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 882libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
780.IP "callback = ev_cb (ev_TYPE *watcher)" 4 883.IP "callback ev_cb (ev_TYPE *watcher)" 4
781.IX Item "callback = ev_cb (ev_TYPE *watcher)" 884.IX Item "callback ev_cb (ev_TYPE *watcher)"
782Returns the callback currently set on the watcher. 885Returns the callback currently set on the watcher.
783.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 886.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
784.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 887.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
785Change the callback. You can change the callback at virtually any time 888Change the callback. You can change the callback at virtually any time
786(modulo threads). 889(modulo threads).
… …
812\& struct my_io *w = (struct my_io *)w_; 915\& struct my_io *w = (struct my_io *)w_;
813\& ... 916\& ...
814\& } 917\& }
815.Ve 918.Ve
816.PP 919.PP
817More interesting and less C\-conformant ways of catsing your callback type 920More interesting and less C\-conformant ways of casting your callback type
818have 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
819.SH "WATCHER TYPES" 959.SH "WATCHER TYPES"
820.IX Header "WATCHER TYPES" 960.IX Header "WATCHER TYPES"
821This section describes each watcher in detail, but will not repeat 961This section describes each watcher in detail, but will not repeat
822information given in the last section. 962information given in the last section. Any initialisation/set macros,
963functions and members specific to the watcher type are explained.
964.PP
965Members are additionally marked with either \fI[read\-only]\fR, meaning that,
966while the watcher is active, you can look at the member and expect some
967sensible content, but you must not modify it (you can modify it while the
968watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
969means you can expect it to have some sensible content while the watcher
970is active, but you can also modify it. Modifying it may not do something
971sensible or take immediate effect (or do anything at all), but libev will
972not crash or malfunction in any way.
823.ie n .Sh """ev_io"" \- is this file descriptor readable or writable" 973.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
824.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" 974.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
825.IX Subsection "ev_io - is this file descriptor readable or writable" 975.IX Subsection "ev_io - is this file descriptor readable or writable?"
826I/O watchers check whether a file descriptor is readable or writable 976I/O watchers check whether a file descriptor is readable or writable
827in each iteration of the event loop (This behaviour is called 977in each iteration of the event loop, or, more precisely, when reading
828level-triggering because you keep receiving events as long as the 978would not block the process and writing would at least be able to write
829condition persists. Remember you can stop the watcher if you don't want to 979some data. This behaviour is called level-triggering because you keep
830act on the event and neither want to receive future events). 980receiving events as long as the condition persists. Remember you can stop
981the watcher if you don't want to act on the event and neither want to
982receive future events.
831.PP 983.PP
832In general you can register as many read and/or write event watchers per 984In general you can register as many read and/or write event watchers per
833fd as you want (as long as you don't confuse yourself). Setting all file 985fd as you want (as long as you don't confuse yourself). Setting all file
834descriptors to non-blocking mode is also usually a good idea (but not 986descriptors to non-blocking mode is also usually a good idea (but not
835required if you know what you are doing). 987required if you know what you are doing).
836.PP 988.PP
837You have to be careful with dup'ed file descriptors, though. Some backends 989You have to be careful with dup'ed file descriptors, though. Some backends
838(the linux epoll backend is a notable example) cannot handle dup'ed file 990(the linux epoll backend is a notable example) cannot handle dup'ed file
839descriptors correctly if you register interest in two or more fds pointing 991descriptors correctly if you register interest in two or more fds pointing
840to the same underlying file/socket etc. description (that is, they share 992to the same underlying file/socket/etc. description (that is, they share
841the same underlying \*(L"file open\*(R"). 993the same underlying \*(L"file open\*(R").
842.PP 994.PP
843If you must do this, then force the use of a known-to-be-good backend 995If you must do this, then force the use of a known-to-be-good backend
844(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and 996(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
845\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). 997\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
998.PP
999Another thing you have to watch out for is that it is quite easy to
1000receive \*(L"spurious\*(R" readyness notifications, that is your callback might
1001be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
1002because there is no data. Not only are some backends known to create a
1003lot of those (for example solaris ports), it is very easy to get into
1004this situation even with a relatively standard program structure. Thus
1005it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
1006\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
1007.PP
1008If you cannot run the fd in non-blocking mode (for example you should not
1009play around with an Xlib connection), then you have to seperately re-test
1010wether a file descriptor is really ready with a known-to-be good interface
1011such as poll (fortunately in our Xlib example, Xlib already does this on
1012its own, so its quite safe to use).
846.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1013.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
847.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1014.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
848.PD 0 1015.PD 0
849.IP "ev_io_set (ev_io *, int fd, int events)" 4 1016.IP "ev_io_set (ev_io *, int fd, int events)" 4
850.IX Item "ev_io_set (ev_io *, int fd, int events)" 1017.IX Item "ev_io_set (ev_io *, int fd, int events)"
851.PD 1018.PD
852Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive 1019Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
853events 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 | 1020rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
854EV_WRITE\*(C'\fR to receive the given events. 1021\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
855.Sp 1022.IP "int fd [read\-only]" 4
856Please note that most of the more scalable backend mechanisms (for example 1023.IX Item "int fd [read-only]"
857epoll and solaris ports) can result in spurious readyness notifications 1024The file descriptor being watched.
858for file descriptors, so you practically need to use non-blocking I/O (and 1025.IP "int events [read\-only]" 4
859treat callback invocation as hint only), or retest separately with a safe 1026.IX Item "int events [read-only]"
860interface before doing I/O (XLib can do this), or force the use of either 1027The events being watched.
861\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this
862problem. Also note that it is quite easy to have your callback invoked
863when the readyness condition is no longer valid even when employing
864typical ways of handling events, so its a good idea to use non-blocking
865I/O unconditionally.
866.PP 1028.PP
867Example: 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
868readable, but only once. Since it is likely line\-buffered, you could 1030readable, but only once. Since it is likely line\-buffered, you could
869attempt to read a whole line in the callback: 1031attempt to read a whole line in the callback.
870.PP 1032.PP
871.Vb 6 1033.Vb 6
872\& static void 1034\& static void
873\& 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)
874\& { 1036\& {
… …
883\& struct ev_io stdin_readable; 1045\& struct ev_io stdin_readable;
884\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1046\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
885\& ev_io_start (loop, &stdin_readable); 1047\& ev_io_start (loop, &stdin_readable);
886\& ev_loop (loop, 0); 1048\& ev_loop (loop, 0);
887.Ve 1049.Ve
888.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" 1050.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
889.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" 1051.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
890.IX Subsection "ev_timer - relative and optionally recurring timeouts" 1052.IX Subsection "ev_timer - relative and optionally repeating timeouts"
891Timer watchers are simple relative timers that generate an event after a 1053Timer watchers are simple relative timers that generate an event after a
892given time, and optionally repeating in regular intervals after that. 1054given time, and optionally repeating in regular intervals after that.
893.PP 1055.PP
894The timers are based on real time, that is, if you register an event that 1056The timers are based on real time, that is, if you register an event that
895times out after an hour and you reset your system clock to last years 1057times out after an hour and you reset your system clock to last years
… …
929.IP "ev_timer_again (loop)" 4 1091.IP "ev_timer_again (loop)" 4
930.IX Item "ev_timer_again (loop)" 1092.IX Item "ev_timer_again (loop)"
931This 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
932repeating. The exact semantics are: 1094repeating. The exact semantics are:
933.Sp 1095.Sp
1096If the timer is pending, its pending status is cleared.
1097.Sp
934If the timer is started but nonrepeating, stop it. 1098If the timer is started but nonrepeating, stop it (as if it timed out).
935.Sp 1099.Sp
936If the timer is repeating, either start it if necessary (with the repeat 1100If the timer is repeating, either start it if necessary (with the
937value), 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.
938.Sp 1102.Sp
939This sounds a bit complicated, but here is a useful and typical 1103This sounds a bit complicated, but here is a useful and typical
940example: Imagine you have a tcp connection and you want a so-called idle 1104example: Imagine you have a tcp connection and you want a so-called idle
941timeout, that is, you want to be called when there have been, say, 60 1105timeout, that is, you want to be called when there have been, say, 60
942seconds of inactivity on the socket. The easiest way to do this is to 1106seconds of inactivity on the socket. The easiest way to do this is to
943configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each 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
944time you successfully read or write some data. If you go into an idle 1108\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
945state where you do not expect data to travel on the socket, you can stop 1109you go into an idle state where you do not expect data to travel on the
946the timer, and again will automatically restart it if need be. 1110socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1111automatically restart it if need be.
1112.Sp
1113That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1114altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1115.Sp
1116.Vb 8
1117\& ev_timer_init (timer, callback, 0., 5.);
1118\& ev_timer_again (loop, timer);
1119\& ...
1120\& timer->again = 17.;
1121\& ev_timer_again (loop, timer);
1122\& ...
1123\& timer->again = 10.;
1124\& ev_timer_again (loop, timer);
1125.Ve
1126.Sp
1127This is more slightly efficient then stopping/starting the timer each time
1128you want to modify its timeout value.
1129.IP "ev_tstamp repeat [read\-write]" 4
1130.IX Item "ev_tstamp repeat [read-write]"
1131The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1132or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1133which is also when any modifications are taken into account.
947.PP 1134.PP
948Example: create a timer that fires after 60 seconds. 1135Example: Create a timer that fires after 60 seconds.
949.PP 1136.PP
950.Vb 5 1137.Vb 5
951\& static void 1138\& static void
952\& 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)
953\& { 1140\& {
… …
959\& struct ev_timer mytimer; 1146\& struct ev_timer mytimer;
960\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1147\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
961\& ev_timer_start (loop, &mytimer); 1148\& ev_timer_start (loop, &mytimer);
962.Ve 1149.Ve
963.PP 1150.PP
964Example: create a timeout timer that times out after 10 seconds of 1151Example: Create a timeout timer that times out after 10 seconds of
965inactivity. 1152inactivity.
966.PP 1153.PP
967.Vb 5 1154.Vb 5
968\& static void 1155\& static void
969\& 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)
… …
982.Vb 3 1169.Vb 3
983\& // and in some piece of code that gets executed on any "activity": 1170\& // and in some piece of code that gets executed on any "activity":
984\& // reset the timeout to start ticking again at 10 seconds 1171\& // reset the timeout to start ticking again at 10 seconds
985\& ev_timer_again (&mytimer); 1172\& ev_timer_again (&mytimer);
986.Ve 1173.Ve
987.ie n .Sh """ev_periodic"" \- to cron or not to cron" 1174.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
988.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" 1175.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
989.IX Subsection "ev_periodic - to cron or not to cron" 1176.IX Subsection "ev_periodic - to cron or not to cron?"
990Periodic watchers are also timers of a kind, but they are very versatile 1177Periodic watchers are also timers of a kind, but they are very versatile
991(and unfortunately a bit complex). 1178(and unfortunately a bit complex).
992.PP 1179.PP
993Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1180Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
994but on wallclock time (absolute time). You can tell a periodic watcher 1181but on wallclock time (absolute time). You can tell a periodic watcher
995to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1182to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
996periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () 1183periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
997+ 10.>) and then reset your system clock to the last year, then it will 1184+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
998take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1185take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
999roughly 10 seconds later and of course not if you reset your system time 1186roughly 10 seconds later and of course not if you reset your system time
1000again). 1187again).
1001.PP 1188.PP
1002They can also be used to implement vastly more complex timers, such as 1189They can also be used to implement vastly more complex timers, such as
… …
1083.IX Item "ev_periodic_again (loop, ev_periodic *)" 1270.IX Item "ev_periodic_again (loop, ev_periodic *)"
1084Simply stops and restarts the periodic watcher again. This is only useful 1271Simply stops and restarts the periodic watcher again. This is only useful
1085when you changed some parameters or the reschedule callback would return 1272when you changed some parameters or the reschedule callback would return
1086a different time than the last time it was called (e.g. in a crond like 1273a different time than the last time it was called (e.g. in a crond like
1087program when the crontabs have changed). 1274program when the crontabs have changed).
1275.IP "ev_tstamp interval [read\-write]" 4
1276.IX Item "ev_tstamp interval [read-write]"
1277The current interval value. Can be modified any time, but changes only
1278take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1279called.
1280.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1281.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1282The current reschedule callback, or \f(CW0\fR, if this functionality is
1283switched off. Can be changed any time, but changes only take effect when
1284the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1088.PP 1285.PP
1089Example: call a callback every hour, or, more precisely, whenever the 1286Example: Call a callback every hour, or, more precisely, whenever the
1090system clock is divisible by 3600. The callback invocation times have 1287system clock is divisible by 3600. The callback invocation times have
1091potentially a lot of jittering, but good long-term stability. 1288potentially a lot of jittering, but good long-term stability.
1092.PP 1289.PP
1093.Vb 5 1290.Vb 5
1094\& static void 1291\& static void
… …
1102\& struct ev_periodic hourly_tick; 1299\& struct ev_periodic hourly_tick;
1103\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1300\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1104\& ev_periodic_start (loop, &hourly_tick); 1301\& ev_periodic_start (loop, &hourly_tick);
1105.Ve 1302.Ve
1106.PP 1303.PP
1107Example: 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:
1108.PP 1305.PP
1109.Vb 1 1306.Vb 1
1110\& #include <math.h> 1307\& #include <math.h>
1111.Ve 1308.Ve
1112.PP 1309.PP
… …
1120.PP 1317.PP
1121.Vb 1 1318.Vb 1
1122\& 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);
1123.Ve 1320.Ve
1124.PP 1321.PP
1125Example: call a callback every hour, starting now: 1322Example: Call a callback every hour, starting now:
1126.PP 1323.PP
1127.Vb 4 1324.Vb 4
1128\& struct ev_periodic hourly_tick; 1325\& struct ev_periodic hourly_tick;
1129\& ev_periodic_init (&hourly_tick, clock_cb, 1326\& ev_periodic_init (&hourly_tick, clock_cb,
1130\& fmod (ev_now (loop), 3600.), 3600., 0); 1327\& fmod (ev_now (loop), 3600.), 3600., 0);
1131\& ev_periodic_start (loop, &hourly_tick); 1328\& ev_periodic_start (loop, &hourly_tick);
1132.Ve 1329.Ve
1133.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" 1330.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1134.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" 1331.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1135.IX Subsection "ev_signal - signal me when a signal gets signalled" 1332.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1136Signal watchers will trigger an event when the process receives a specific 1333Signal watchers will trigger an event when the process receives a specific
1137signal one or more times. Even though signals are very asynchronous, libev 1334signal one or more times. Even though signals are very asynchronous, libev
1138will try it's best to deliver signals synchronously, i.e. as part of the 1335will try it's best to deliver signals synchronously, i.e. as part of the
1139normal event processing, like any other event. 1336normal event processing, like any other event.
1140.PP 1337.PP
… …
1150.IP "ev_signal_set (ev_signal *, int signum)" 4 1347.IP "ev_signal_set (ev_signal *, int signum)" 4
1151.IX Item "ev_signal_set (ev_signal *, int signum)" 1348.IX Item "ev_signal_set (ev_signal *, int signum)"
1152.PD 1349.PD
1153Configures the watcher to trigger on the given signal number (usually one 1350Configures the watcher to trigger on the given signal number (usually one
1154of the \f(CW\*(C`SIGxxx\*(C'\fR constants). 1351of the \f(CW\*(C`SIGxxx\*(C'\fR constants).
1352.IP "int signum [read\-only]" 4
1353.IX Item "int signum [read-only]"
1354The signal the watcher watches out for.
1155.ie n .Sh """ev_child"" \- wait for pid status changes" 1355.ie n .Sh """ev_child"" \- watch out for process status changes"
1156.el .Sh "\f(CWev_child\fP \- wait for pid status changes" 1356.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1157.IX Subsection "ev_child - wait for pid status changes" 1357.IX Subsection "ev_child - watch out for process status changes"
1158Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1358Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1159some child status changes (most typically when a child of yours dies). 1359some child status changes (most typically when a child of yours dies).
1160.IP "ev_child_init (ev_child *, callback, int pid)" 4 1360.IP "ev_child_init (ev_child *, callback, int pid)" 4
1161.IX Item "ev_child_init (ev_child *, callback, int pid)" 1361.IX Item "ev_child_init (ev_child *, callback, int pid)"
1162.PD 0 1362.PD 0
… …
1167\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look 1367\&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look
1168at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see 1368at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see
1169the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems 1369the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems
1170\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the 1370\&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the
1171process causing the status change. 1371process causing the status change.
1372.IP "int pid [read\-only]" 4
1373.IX Item "int pid [read-only]"
1374The process id this watcher watches out for, or \f(CW0\fR, meaning any process id.
1375.IP "int rpid [read\-write]" 4
1376.IX Item "int rpid [read-write]"
1377The process id that detected a status change.
1378.IP "int rstatus [read\-write]" 4
1379.IX Item "int rstatus [read-write]"
1380The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1381\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1172.PP 1382.PP
1173Example: 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.
1174.PP 1384.PP
1175.Vb 5 1385.Vb 5
1176\& static void 1386\& static void
1177\& 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)
1178\& { 1388\& {
… …
1183.Vb 3 1393.Vb 3
1184\& struct ev_signal signal_watcher; 1394\& struct ev_signal signal_watcher;
1185\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 1395\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1186\& ev_signal_start (loop, &sigint_cb); 1396\& ev_signal_start (loop, &sigint_cb);
1187.Ve 1397.Ve
1398.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1399.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1400.IX Subsection "ev_stat - did the file attributes just change?"
1401This watches a filesystem path for attribute changes. That is, it calls
1402\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1403compared to the last time, invoking the callback if it did.
1404.PP
1405The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1406not exist\*(R" is a status change like any other. The condition \*(L"path does
1407not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1408otherwise always forced to be at least one) and all the other fields of
1409the stat buffer having unspecified contents.
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
1414Since there is no standard to do this, the portable implementation simply
1415calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1416can specify a recommended polling interval for this case. If you specify
1417a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1418unspecified default\fR value will be used (which you can expect to be around
1419five seconds, although this might change dynamically). Libev will also
1420impose a minimum interval which is currently around \f(CW0.1\fR, but thats
1421usually overkill.
1422.PP
1423This watcher type is not meant for massive numbers of stat watchers,
1424as even with OS-supported change notifications, this can be
1425resource\-intensive.
1426.PP
1427At the time of this writing, only the Linux inotify interface is
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.
1434.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1435.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1436.PD 0
1437.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1438.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
1439.PD
1440Configures the watcher to wait for status changes of the given
1441\&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to
1442be detected and should normally be specified as \f(CW0\fR to let libev choose
1443a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same
1444path for as long as the watcher is active.
1445.Sp
1446The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected,
1447relative to the attributes at the time the watcher was started (or the
1448last change was detected).
1449.IP "ev_stat_stat (ev_stat *)" 4
1450.IX Item "ev_stat_stat (ev_stat *)"
1451Updates the stat buffer immediately with new values. If you change the
1452watched path in your callback, you could call this fucntion to avoid
1453detecting this change (while introducing a race condition). Can also be
1454useful simply to find out the new values.
1455.IP "ev_statdata attr [read\-only]" 4
1456.IX Item "ev_statdata attr [read-only]"
1457The most-recently detected attributes of the file. Although the type is of
1458\&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types
1459suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there
1460was some error while \f(CW\*(C`stat\*(C'\fRing the file.
1461.IP "ev_statdata prev [read\-only]" 4
1462.IX Item "ev_statdata prev [read-only]"
1463The previous attributes of the file. The callback gets invoked whenever
1464\&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR.
1465.IP "ev_tstamp interval [read\-only]" 4
1466.IX Item "ev_tstamp interval [read-only]"
1467The specified interval.
1468.IP "const char *path [read\-only]" 4
1469.IX Item "const char *path [read-only]"
1470The filesystem path that is being watched.
1471.PP
1472Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1473.PP
1474.Vb 15
1475\& static void
1476\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1477\& {
1478\& /* /etc/passwd changed in some way */
1479\& if (w->attr.st_nlink)
1480\& {
1481\& printf ("passwd current size %ld\en", (long)w->attr.st_size);
1482\& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime);
1483\& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime);
1484\& }
1485\& else
1486\& /* you shalt not abuse printf for puts */
1487\& puts ("wow, /etc/passwd is not there, expect problems. "
1488\& "if this is windows, they already arrived\en");
1489\& }
1490.Ve
1491.PP
1492.Vb 2
1493\& ...
1494\& ev_stat passwd;
1495.Ve
1496.PP
1497.Vb 2
1498\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
1499\& ev_stat_start (loop, &passwd);
1500.Ve
1188.ie n .Sh """ev_idle"" \- when you've got nothing better to do" 1501.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1189.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" 1502.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1190.IX Subsection "ev_idle - when you've got nothing better to do" 1503.IX Subsection "ev_idle - when you've got nothing better to do..."
1191Idle watchers trigger events when there are no other events are pending 1504Idle watchers trigger events when there are no other events are pending
1192(prepare, check and other idle watchers do not count). That is, as long 1505(prepare, check and other idle watchers do not count). That is, as long
1193as your process is busy handling sockets or timeouts (or even signals, 1506as your process is busy handling sockets or timeouts (or even signals,
1194imagine) it will not be triggered. But when your process is idle all idle 1507imagine) it will not be triggered. But when your process is idle all idle
1195watchers are being called again and again, once per event loop iteration \- 1508watchers are being called again and again, once per event loop iteration \-
… …
1207.IX Item "ev_idle_init (ev_signal *, callback)" 1520.IX Item "ev_idle_init (ev_signal *, callback)"
1208Initialises and configures the idle watcher \- it has no parameters of any 1521Initialises and configures the idle watcher \- it has no parameters of any
1209kind. 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,
1210believe me. 1523believe me.
1211.PP 1524.PP
1212Example: 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
1213callback, free it. Alos, use no error checking, as usual. 1526callback, free it. Also, use no error checking, as usual.
1214.PP 1527.PP
1215.Vb 7 1528.Vb 7
1216\& static void 1529\& static void
1217\& 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)
1218\& { 1531\& {
… …
1225.Vb 3 1538.Vb 3
1226\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 1539\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1227\& ev_idle_init (idle_watcher, idle_cb); 1540\& ev_idle_init (idle_watcher, idle_cb);
1228\& ev_idle_start (loop, idle_cb); 1541\& ev_idle_start (loop, idle_cb);
1229.Ve 1542.Ve
1230.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" 1543.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1231.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" 1544.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1232.IX Subsection "ev_prepare and ev_check - customise your event loop" 1545.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1233Prepare and check watchers are usually (but not always) used in tandem: 1546Prepare and check watchers are usually (but not always) used in tandem:
1234prepare watchers get invoked before the process blocks and check watchers 1547prepare watchers get invoked before the process blocks and check watchers
1235afterwards. 1548afterwards.
1236.PP 1549.PP
1550You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter
1551the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
1552watchers. Other loops than the current one are fine, however. The
1553rationale behind this is that you do not need to check for recursion in
1554those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking,
1555\&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be
1556called in pairs bracketing the blocking call.
1557.PP
1237Their main purpose is to integrate other event mechanisms into libev and 1558Their main purpose is to integrate other event mechanisms into libev and
1238their use is somewhat advanced. This could be used, for example, to track 1559their use is somewhat advanced. This could be used, for example, to track
1239variable changes, implement your own watchers, integrate net-snmp or a 1560variable changes, implement your own watchers, integrate net-snmp or a
1240coroutine library and lots more. 1561coroutine library and lots more. They are also occasionally useful if
1562you cache some data and want to flush it before blocking (for example,
1563in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR
1564watcher).
1241.PP 1565.PP
1242This is done by examining in each prepare call which file descriptors need 1566This is done by examining in each prepare call which file descriptors need
1243to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 1567to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1244them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 1568them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1245provide just this functionality). Then, in the check watcher you check for 1569provide just this functionality). Then, in the check watcher you check for
… …
1264.PD 1588.PD
1265Initialises and configures the prepare or check watcher \- they have no 1589Initialises and configures the prepare or check watcher \- they have no
1266parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1590parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1267macros, but using them is utterly, utterly and completely pointless. 1591macros, but using them is utterly, utterly and completely pointless.
1268.PP 1592.PP
1269Example: *TODO*. 1593Example: To include a library such as adns, you would add \s-1IO\s0 watchers
1594and a timeout watcher in a prepare handler, as required by libadns, and
1595in a check watcher, destroy them and call into libadns. What follows is
1596pseudo-code only of course:
1597.PP
1598.Vb 2
1599\& static ev_io iow [nfd];
1600\& static ev_timer tw;
1601.Ve
1602.PP
1603.Vb 9
1604\& static void
1605\& io_cb (ev_loop *loop, ev_io *w, int revents)
1606\& {
1607\& // set the relevant poll flags
1608\& // could also call adns_processreadable etc. here
1609\& struct pollfd *fd = (struct pollfd *)w->data;
1610\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1611\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1612\& }
1613.Ve
1614.PP
1615.Vb 7
1616\& // create io watchers for each fd and a timer before blocking
1617\& static void
1618\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1619\& {
1620\& int timeout = 3600000;truct pollfd fds [nfd];
1621\& // actual code will need to loop here and realloc etc.
1622\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1623.Ve
1624.PP
1625.Vb 3
1626\& /* the callback is illegal, but won't be called as we stop during check */
1627\& ev_timer_init (&tw, 0, timeout * 1e-3);
1628\& ev_timer_start (loop, &tw);
1629.Ve
1630.PP
1631.Vb 6
1632\& // create on ev_io per pollfd
1633\& for (int i = 0; i < nfd; ++i)
1634\& {
1635\& ev_io_init (iow + i, io_cb, fds [i].fd,
1636\& ((fds [i].events & POLLIN ? EV_READ : 0)
1637\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1638.Ve
1639.PP
1640.Vb 5
1641\& fds [i].revents = 0;
1642\& iow [i].data = fds + i;
1643\& ev_io_start (loop, iow + i);
1644\& }
1645\& }
1646.Ve
1647.PP
1648.Vb 5
1649\& // stop all watchers after blocking
1650\& static void
1651\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1652\& {
1653\& ev_timer_stop (loop, &tw);
1654.Ve
1655.PP
1656.Vb 2
1657\& for (int i = 0; i < nfd; ++i)
1658\& ev_io_stop (loop, iow + i);
1659.Ve
1660.PP
1661.Vb 2
1662\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1663\& }
1664.Ve
1270.ie n .Sh """ev_embed"" \- when one backend isn't enough" 1665.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1271.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough" 1666.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1272.IX Subsection "ev_embed - when one backend isn't enough" 1667.IX Subsection "ev_embed - when one backend isn't enough..."
1273This is a rather advanced watcher type that lets you embed one event loop 1668This is a rather advanced watcher type that lets you embed one event loop
1274into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded 1669into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
1275loop, other types of watchers might be handled in a delayed or incorrect 1670loop, other types of watchers might be handled in a delayed or incorrect
1276fashion and must not be used). 1671fashion and must not be used).
1277.PP 1672.PP
… …
1357.IP "ev_embed_sweep (loop, ev_embed *)" 4 1752.IP "ev_embed_sweep (loop, ev_embed *)" 4
1358.IX Item "ev_embed_sweep (loop, ev_embed *)" 1753.IX Item "ev_embed_sweep (loop, ev_embed *)"
1359Make a single, non-blocking sweep over the embedded loop. This works 1754Make a single, non-blocking sweep over the embedded loop. This works
1360similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 1755similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1361apropriate way for embedded loops. 1756apropriate way for embedded loops.
1757.IP "struct ev_loop *loop [read\-only]" 4
1758.IX Item "struct ev_loop *loop [read-only]"
1759The embedded event loop.
1760.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1761.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1762.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1763Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
1764whoever is a good citizen cared to tell libev about it by calling
1765\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1766event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1767and only in the child after the fork. If whoever good citizen calling
1768\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1769handlers will be invoked, too, of course.
1770.IP "ev_fork_init (ev_signal *, callback)" 4
1771.IX Item "ev_fork_init (ev_signal *, callback)"
1772Initialises and configures the fork watcher \- it has no parameters of any
1773kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1774believe me.
1362.SH "OTHER FUNCTIONS" 1775.SH "OTHER FUNCTIONS"
1363.IX Header "OTHER FUNCTIONS" 1776.IX Header "OTHER FUNCTIONS"
1364There are some other functions of possible interest. Described. Here. Now. 1777There are some other functions of possible interest. Described. Here. Now.
1365.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 1778.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
1366.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 1779.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
… …
1428.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 1841.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
1429.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." 1842.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
1430.PD 1843.PD
1431.SH "\*(C+ SUPPORT" 1844.SH "\*(C+ SUPPORT"
1432.IX Header " SUPPORT" 1845.IX Header " SUPPORT"
1433\&\s-1TBD\s0. 1846Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
1847you to use some convinience methods to start/stop watchers and also change
1848the callback model to a model using method callbacks on objects.
1849.PP
1850To use it,
1851.PP
1852.Vb 1
1853\& #include <ev++.h>
1854.Ve
1855.PP
1856(it is not installed by default). This automatically includes \fIev.h\fR
1857and puts all of its definitions (many of them macros) into the global
1858namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
1859.PP
1860It should support all the same embedding options as \fIev.h\fR, most notably
1861\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1862.PP
1863Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1864.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1865.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1866.IX Item "ev::READ, ev::WRITE etc."
1867These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
1868macros from \fIev.h\fR.
1869.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
1870.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
1871.IX Item "ev::tstamp, ev::now"
1872Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
1873.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4
1874.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
1875.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
1876For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
1877the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
1878which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1879defines by many implementations.
1880.Sp
1881All of those classes have these methods:
1882.RS 4
1883.IP "ev::TYPE::TYPE (object *, object::method *)" 4
1884.IX Item "ev::TYPE::TYPE (object *, object::method *)"
1885.PD 0
1886.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
1887.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
1888.IP "ev::TYPE::~TYPE" 4
1889.IX Item "ev::TYPE::~TYPE"
1890.PD
1891The constructor takes a pointer to an object and a method pointer to
1892the event handler callback to call in this class. The constructor calls
1893\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method
1894before starting it. If you do not specify a loop then the constructor
1895automatically associates the default loop with this watcher.
1896.Sp
1897The destructor automatically stops the watcher if it is active.
1898.IP "w\->set (struct ev_loop *)" 4
1899.IX Item "w->set (struct ev_loop *)"
1900Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1901do this when the watcher is inactive (and not pending either).
1902.IP "w\->set ([args])" 4
1903.IX Item "w->set ([args])"
1904Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1905called at least once. Unlike the C counterpart, an active watcher gets
1906automatically stopped and restarted.
1907.IP "w\->start ()" 4
1908.IX Item "w->start ()"
1909Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
1910constructor already takes the loop.
1911.IP "w\->stop ()" 4
1912.IX Item "w->stop ()"
1913Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1914.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1915.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
1916.IX Item "w->again () ev::timer, ev::periodic only"
1917For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
1918\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
1919.ie n .IP "w\->sweep () ""ev::embed"" only" 4
1920.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
1921.IX Item "w->sweep () ev::embed only"
1922Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
1923.ie n .IP "w\->update () ""ev::stat"" only" 4
1924.el .IP "w\->update () \f(CWev::stat\fR only" 4
1925.IX Item "w->update () ev::stat only"
1926Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
1927.RE
1928.RS 4
1929.RE
1930.PP
1931Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
1932the constructor.
1933.PP
1934.Vb 4
1935\& class myclass
1936\& {
1937\& ev_io io; void io_cb (ev::io &w, int revents);
1938\& ev_idle idle void idle_cb (ev::idle &w, int revents);
1939.Ve
1940.PP
1941.Vb 2
1942\& myclass ();
1943\& }
1944.Ve
1945.PP
1946.Vb 6
1947\& myclass::myclass (int fd)
1948\& : io (this, &myclass::io_cb),
1949\& idle (this, &myclass::idle_cb)
1950\& {
1951\& io.start (fd, ev::READ);
1952\& }
1953.Ve
1954.SH "MACRO MAGIC"
1955.IX Header "MACRO MAGIC"
1956Libev can be compiled with a variety of options, the most fundemantal is
1957\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and
1958callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1959.PP
1960To make it easier to write programs that cope with either variant, the
1961following macros are defined:
1962.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
1963.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
1964.IX Item "EV_A, EV_A_"
1965This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
1966loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
1967\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
1968.Sp
1969.Vb 3
1970\& ev_unref (EV_A);
1971\& ev_timer_add (EV_A_ watcher);
1972\& ev_loop (EV_A_ 0);
1973.Ve
1974.Sp
1975It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
1976which is often provided by the following macro.
1977.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
1978.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
1979.IX Item "EV_P, EV_P_"
1980This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
1981loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
1982\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
1983.Sp
1984.Vb 2
1985\& // this is how ev_unref is being declared
1986\& static void ev_unref (EV_P);
1987.Ve
1988.Sp
1989.Vb 2
1990\& // this is how you can declare your typical callback
1991\& static void cb (EV_P_ ev_timer *w, int revents)
1992.Ve
1993.Sp
1994It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
1995suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
1996.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
1997.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1998.IX Item "EV_DEFAULT, EV_DEFAULT_"
1999Similar to the other two macros, this gives you the value of the default
2000loop, if multiple loops are supported (\*(L"ev loop default\*(R").
2001.PP
2002Example: Declare and initialise a check watcher, utilising the above
2003macros so it will work regardless of wether multiple loops are supported
2004or not.
2005.PP
2006.Vb 5
2007\& static void
2008\& check_cb (EV_P_ ev_timer *w, int revents)
2009\& {
2010\& ev_check_stop (EV_A_ w);
2011\& }
2012.Ve
2013.PP
2014.Vb 4
2015\& ev_check check;
2016\& ev_check_init (&check, check_cb);
2017\& ev_check_start (EV_DEFAULT_ &check);
2018\& ev_loop (EV_DEFAULT_ 0);
2019.Ve
2020.SH "EMBEDDING"
2021.IX Header "EMBEDDING"
2022Libev can (and often is) directly embedded into host
2023applications. Examples of applications that embed it include the Deliantra
2024Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
2025and rxvt\-unicode.
2026.PP
2027The goal is to enable you to just copy the neecssary files into your
2028source directory without having to change even a single line in them, so
2029you can easily upgrade by simply copying (or having a checked-out copy of
2030libev somewhere in your source tree).
2031.Sh "\s-1FILESETS\s0"
2032.IX Subsection "FILESETS"
2033Depending on what features you need you need to include one or more sets of files
2034in your app.
2035.PP
2036\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
2037.IX Subsection "CORE EVENT LOOP"
2038.PP
2039To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
2040configuration (no autoconf):
2041.PP
2042.Vb 2
2043\& #define EV_STANDALONE 1
2044\& #include "ev.c"
2045.Ve
2046.PP
2047This will automatically include \fIev.h\fR, too, and should be done in a
2048single C source file only to provide the function implementations. To use
2049it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
2050done by writing a wrapper around \fIev.h\fR that you can include instead and
2051where you can put other configuration options):
2052.PP
2053.Vb 2
2054\& #define EV_STANDALONE 1
2055\& #include "ev.h"
2056.Ve
2057.PP
2058Both header files and implementation files can be compiled with a \*(C+
2059compiler (at least, thats a stated goal, and breakage will be treated
2060as a bug).
2061.PP
2062You need the following files in your source tree, or in a directory
2063in your include path (e.g. in libev/ when using \-Ilibev):
2064.PP
2065.Vb 4
2066\& ev.h
2067\& ev.c
2068\& ev_vars.h
2069\& ev_wrap.h
2070.Ve
2071.PP
2072.Vb 1
2073\& ev_win32.c required on win32 platforms only
2074.Ve
2075.PP
2076.Vb 5
2077\& ev_select.c only when select backend is enabled (which is enabled by default)
2078\& ev_poll.c only when poll backend is enabled (disabled by default)
2079\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2080\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2081\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2082.Ve
2083.PP
2084\&\fIev.c\fR includes the backend files directly when enabled, so you only need
2085to compile this single file.
2086.PP
2087\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
2088.IX Subsection "LIBEVENT COMPATIBILITY API"
2089.PP
2090To include the libevent compatibility \s-1API\s0, also include:
2091.PP
2092.Vb 1
2093\& #include "event.c"
2094.Ve
2095.PP
2096in the file including \fIev.c\fR, and:
2097.PP
2098.Vb 1
2099\& #include "event.h"
2100.Ve
2101.PP
2102in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
2103.PP
2104You need the following additional files for this:
2105.PP
2106.Vb 2
2107\& event.h
2108\& event.c
2109.Ve
2110.PP
2111\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
2112.IX Subsection "AUTOCONF SUPPORT"
2113.PP
2114Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in
2115whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
2116\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
2117include \fIconfig.h\fR and configure itself accordingly.
2118.PP
2119For this of course you need the m4 file:
2120.PP
2121.Vb 1
2122\& libev.m4
2123.Ve
2124.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
2125.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
2126Libev can be configured via a variety of preprocessor symbols you have to define
2127before including any of its files. The default is not to build for multiplicity
2128and only include the select backend.
2129.IP "\s-1EV_STANDALONE\s0" 4
2130.IX Item "EV_STANDALONE"
2131Must always be \f(CW1\fR if you do not use autoconf configuration, which
2132keeps libev from including \fIconfig.h\fR, and it also defines dummy
2133implementations for some libevent functions (such as logging, which is not
2134supported). It will also not define any of the structs usually found in
2135\&\fIevent.h\fR that are not directly supported by the libev core alone.
2136.IP "\s-1EV_USE_MONOTONIC\s0" 4
2137.IX Item "EV_USE_MONOTONIC"
2138If defined to be \f(CW1\fR, libev will try to detect the availability of the
2139monotonic clock option at both compiletime and runtime. Otherwise no use
2140of the monotonic clock option will be attempted. If you enable this, you
2141usually have to link against librt or something similar. Enabling it when
2142the functionality isn't available is safe, though, althoguh you have
2143to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2144function is hiding in (often \fI\-lrt\fR).
2145.IP "\s-1EV_USE_REALTIME\s0" 4
2146.IX Item "EV_USE_REALTIME"
2147If defined to be \f(CW1\fR, libev will try to detect the availability of the
2148realtime clock option at compiletime (and assume its availability at
2149runtime if successful). Otherwise no use of the realtime clock option will
2150be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2151(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
2152in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2153.IP "\s-1EV_USE_SELECT\s0" 4
2154.IX Item "EV_USE_SELECT"
2155If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2156\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
2157other method takes over, select will be it. Otherwise the select backend
2158will not be compiled in.
2159.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
2160.IX Item "EV_SELECT_USE_FD_SET"
2161If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
2162structure. This is useful if libev doesn't compile due to a missing
2163\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on
2164exotic systems. This usually limits the range of file descriptors to some
2165low limit such as 1024 or might have other limitations (winsocket only
2166allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
2167influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
2168.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
2169.IX Item "EV_SELECT_IS_WINSOCKET"
2170When defined to \f(CW1\fR, the select backend will assume that
2171select/socket/connect etc. don't understand file descriptors but
2172wants osf handles on win32 (this is the case when the select to
2173be used is the winsock select). This means that it will call
2174\&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
2175it is assumed that all these functions actually work on fds, even
2176on win32. Should not be defined on non\-win32 platforms.
2177.IP "\s-1EV_USE_POLL\s0" 4
2178.IX Item "EV_USE_POLL"
2179If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
2180backend. Otherwise it will be enabled on non\-win32 platforms. It
2181takes precedence over select.
2182.IP "\s-1EV_USE_EPOLL\s0" 4
2183.IX Item "EV_USE_EPOLL"
2184If defined to be \f(CW1\fR, libev will compile in support for the Linux
2185\&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime,
2186otherwise another method will be used as fallback. This is the
2187preferred backend for GNU/Linux systems.
2188.IP "\s-1EV_USE_KQUEUE\s0" 4
2189.IX Item "EV_USE_KQUEUE"
2190If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
2191\&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime,
2192otherwise another method will be used as fallback. This is the preferred
2193backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
2194supports some types of fds correctly (the only platform we found that
2195supports ptys for example was NetBSD), so kqueue might be compiled in, but
2196not be used unless explicitly requested. The best way to use it is to find
2197out whether kqueue supports your type of fd properly and use an embedded
2198kqueue loop.
2199.IP "\s-1EV_USE_PORT\s0" 4
2200.IX Item "EV_USE_PORT"
2201If defined to be \f(CW1\fR, libev will compile in support for the Solaris
220210 port style backend. Its availability will be detected at runtime,
2203otherwise another method will be used as fallback. This is the preferred
2204backend for Solaris 10 systems.
2205.IP "\s-1EV_USE_DEVPOLL\s0" 4
2206.IX Item "EV_USE_DEVPOLL"
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.
2213.IP "\s-1EV_H\s0" 4
2214.IX Item "EV_H"
2215The name of the \fIev.h\fR header file used to include it. The default if
2216undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2217can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
2218.IP "\s-1EV_CONFIG_H\s0" 4
2219.IX Item "EV_CONFIG_H"
2220If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
2221\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
2222\&\f(CW\*(C`EV_H\*(C'\fR, above.
2223.IP "\s-1EV_EVENT_H\s0" 4
2224.IX Item "EV_EVENT_H"
2225Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
2226of how the \fIevent.h\fR header can be found.
2227.IP "\s-1EV_PROTOTYPES\s0" 4
2228.IX Item "EV_PROTOTYPES"
2229If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
2230prototypes, but still define all the structs and other symbols. This is
2231occasionally useful if you want to provide your own wrapper functions
2232around libev functions.
2233.IP "\s-1EV_MULTIPLICITY\s0" 4
2234.IX Item "EV_MULTIPLICITY"
2235If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2236will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2237additional independent event loops. Otherwise there will be no support
2238for multiple event loops and there is no first event loop pointer
2239argument. Instead, all functions act on the single default loop.
2240.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2241.IX Item "EV_PERIODIC_ENABLE"
2242If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2243defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2244code.
2245.IP "\s-1EV_EMBED_ENABLE\s0" 4
2246.IX Item "EV_EMBED_ENABLE"
2247If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
2248defined to be \f(CW0\fR, then they are not.
2249.IP "\s-1EV_STAT_ENABLE\s0" 4
2250.IX Item "EV_STAT_ENABLE"
2251If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If
2252defined to be \f(CW0\fR, then they are not.
2253.IP "\s-1EV_FORK_ENABLE\s0" 4
2254.IX Item "EV_FORK_ENABLE"
2255If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If
2256defined to be \f(CW0\fR, then they are not.
2257.IP "\s-1EV_MINIMAL\s0" 4
2258.IX Item "EV_MINIMAL"
2259If you need to shave off some kilobytes of code at the expense of some
2260speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override
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).
2275.IP "\s-1EV_COMMON\s0" 4
2276.IX Item "EV_COMMON"
2277By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2278this macro to a something else you can include more and other types of
2279members. You have to define it each time you include one of the files,
2280though, and it must be identical each time.
2281.Sp
2282For example, the perl \s-1EV\s0 module uses something like this:
2283.Sp
2284.Vb 3
2285\& #define EV_COMMON \e
2286\& SV *self; /* contains this struct */ \e
2287\& SV *cb_sv, *fh /* note no trailing ";" */
2288.Ve
2289.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
2290.IX Item "EV_CB_DECLARE (type)"
2291.PD 0
2292.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
2293.IX Item "EV_CB_INVOKE (watcher, revents)"
2294.IP "ev_set_cb (ev, cb)" 4
2295.IX Item "ev_set_cb (ev, cb)"
2296.PD
2297Can be used to change the callback member declaration in each watcher,
2298and the way callbacks are invoked and set. Must expand to a struct member
2299definition and a statement, respectively. See the \fIev.v\fR header file for
2300their default definitions. One possible use for overriding these is to
2301avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2302method calls instead of plain function calls in \*(C+.
2303.Sh "\s-1EXAMPLES\s0"
2304.IX Subsection "EXAMPLES"
2305For a real-world example of a program the includes libev
2306verbatim, you can have a look at the \s-1EV\s0 perl module
2307(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
2308the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
2309interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2310will be compiled. It is pretty complex because it provides its own header
2311file.
2312.Sp
2313The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2314that everybody includes and which overrides some configure choices:
2315.Sp
2316.Vb 9
2317\& #define EV_MINIMAL 1
2318\& #define EV_USE_POLL 0
2319\& #define EV_MULTIPLICITY 0
2320\& #define EV_PERIODIC_ENABLE 0
2321\& #define EV_STAT_ENABLE 0
2322\& #define EV_FORK_ENABLE 0
2323\& #define EV_CONFIG_H <config.h>
2324\& #define EV_MINPRI 0
2325\& #define EV_MAXPRI 0
2326.Ve
2327.Sp
2328.Vb 1
2329\& #include "ev++.h"
2330.Ve
2331.Sp
2332And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
2333.Sp
2334.Vb 2
2335\& #include "ev_cpp.h"
2336\& #include "ev.c"
2337.Ve
2338.SH "COMPLEXITIES"
2339.IX Header "COMPLEXITIES"
2340In this section the complexities of (many of) the algorithms used inside
2341libev will be explained. For complexity discussions about backends see the
2342documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2343.RS 4
2344.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2345.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2346.PD 0
2347.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2348.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2349.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2350.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2351.IP "Stopping check/prepare/idle watchers: O(1)" 4
2352.IX Item "Stopping check/prepare/idle watchers: O(1)"
2353.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2354.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2355.IP "Finding the next timer per loop iteration: O(1)" 4
2356.IX Item "Finding the next timer per loop iteration: O(1)"
2357.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2358.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2359.IP "Activating one watcher: O(1)" 4
2360.IX Item "Activating one watcher: O(1)"
2361.RE
2362.RS 4
2363.PD
1434.SH "AUTHOR" 2364.SH "AUTHOR"
1435.IX Header "AUTHOR" 2365.IX Header "AUTHOR"
1436Marc Lehmann <libev@schmorp.de>. 2366Marc Lehmann <libev@schmorp.de>.

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