[ViewVC] Diff of: cvs/libev/ev.3

Comparing libev/ev.3 (file contents):
Revision 1.8 by root, Fri Nov 23 15:26:08 2007 UTC vs.
Revision 1.20 by root, Mon Nov 26 09:52:14 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 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation"	132	.TH "<STANDARD INPUT>" 1 "2007-11-26" "perl v5.8.8" "User Contributed Perl Documentation"
133	.SH "NAME"	133	.SH "NAME"
134	libev \- a high performance full\-featured event loop written in C	134	libev \- 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
…		…
173	.IX Header "TIME REPRESENTATION"	173	.IX Header "TIME REPRESENTATION"
174	Libev represents time as a single floating point number, representing the	174	Libev represents time as a single floating point number, representing the
175	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near	175	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
176	the beginning of 1970, details are complicated, don't ask). This type is	176	the beginning of 1970, details are complicated, don't ask). This type is
177	called \f(CW\(C`ev_tstamp\(C'\fR, which is what you should use too. It usually aliases	177	called \f(CW\(C`ev_tstamp\(C'\fR, which is what you should use too. It usually aliases
178	to the double type in C.	178	to the \f(CW\(C`double\(C'\fR type in C, and when you need to do any calculations on
		179	it, you should treat it as such.
179	.SH "GLOBAL FUNCTIONS"	180	.SH "GLOBAL FUNCTIONS"
180	.IX Header "GLOBAL FUNCTIONS"	181	.IX Header "GLOBAL FUNCTIONS"
181	These functions can be called anytime, even before initialising the	182	These functions can be called anytime, even before initialising the
182	library in any way.	183	library in any way.
183	.IP "ev_tstamp ev_time ()" 4	184	.IP "ev_tstamp ev_time ()" 4
…		…
199	.Sp	200	.Sp
200	Usually, it's a good idea to terminate if the major versions mismatch,	201	Usually, it's a good idea to terminate if the major versions mismatch,
201	as this indicates an incompatible change. Minor versions are usually	202	as this indicates an incompatible change. Minor versions are usually
202	compatible to older versions, so a larger minor version alone is usually	203	compatible to older versions, so a larger minor version alone is usually
203	not a problem.	204	not a problem.
		205	.Sp
		206	Example: make sure we haven't accidentally been linked against the wrong
		207	version:
		208	.Sp
		209	.Vb 3
		210	\& assert (("libev version mismatch",
		211	\& ev_version_major () == EV_VERSION_MAJOR
		212	\& && ev_version_minor () >= EV_VERSION_MINOR));
		213	.Ve
204	.IP "unsigned int ev_supported_backends ()" 4	214	.IP "unsigned int ev_supported_backends ()" 4
205	.IX Item "unsigned int ev_supported_backends ()"	215	.IX Item "unsigned int ev_supported_backends ()"
206	Return the set of all backends (i.e. their corresponding \f(CW\(C`EV_BACKEND_\*(C'\fR	216	Return the set of all backends (i.e. their corresponding \f(CW\(C`EV_BACKEND_\*(C'\fR
207	value) compiled into this binary of libev (independent of their	217	value) compiled into this binary of libev (independent of their
208	availability on the system you are running on). See \f(CW\(C`ev_default_loop\(C'\fR for	218	availability on the system you are running on). See \f(CW\(C`ev_default_loop\(C'\fR for
209	a description of the set values.	219	a description of the set values.
		220	.Sp
		221	Example: make sure we have the epoll method, because yeah this is cool and
		222	a must have and can we have a torrent of it please!!!11
		223	.Sp
		224	.Vb 2
		225	\& assert (("sorry, no epoll, no sex",
		226	\& ev_supported_backends () & EVBACKEND_EPOLL));
		227	.Ve
210	.IP "unsigned int ev_recommended_backends ()" 4	228	.IP "unsigned int ev_recommended_backends ()" 4
211	.IX Item "unsigned int ev_recommended_backends ()"	229	.IX Item "unsigned int ev_recommended_backends ()"
212	Return the set of all backends compiled into this binary of libev and also	230	Return the set of all backends compiled into this binary of libev and also
213	recommended for this platform. This set is often smaller than the one	231	recommended for this platform. This set is often smaller than the one
214	returned by \f(CW\(C`ev_supported_backends\(C'\fR, as for example kqueue is broken on	232	returned by \f(CW\(C`ev_supported_backends\(C'\fR, as for example kqueue is broken on
215	most BSDs and will not be autodetected unless you explicitly request it	233	most BSDs and will not be autodetected unless you explicitly request it
216	(assuming you know what you are doing). This is the set of backends that	234	(assuming you know what you are doing). This is the set of backends that
217	libev will probe for if you specify no backends explicitly.	235	libev will probe for if you specify no backends explicitly.
		236	.IP "unsigned int ev_embeddable_backends ()" 4
		237	.IX Item "unsigned int ev_embeddable_backends ()"
		238	Returns the set of backends that are embeddable in other event loops. This
		239	is the theoretical, all\-platform, value. To find which backends
		240	might be supported on the current system, you would need to look at
		241	\&\f(CW\(C`ev_embeddable_backends () & ev_supported_backends ()\(C'\fR, likewise for
		242	recommended ones.
		243	.Sp
		244	See the description of \f(CW\(C`ev_embed\(C'\fR watchers for more info.
218	.IP "ev_set_allocator (void (cb)(void *ptr, long size))" 4	245	.IP "ev_set_allocator (void (cb)(void *ptr, long size))" 4
219	.IX Item "ev_set_allocator (void (cb)(void *ptr, long size))"	246	.IX Item "ev_set_allocator (void (cb)(void *ptr, long size))"
220	Sets the allocation function to use (the prototype is similar to the	247	Sets the allocation function to use (the prototype is similar to the
221	realloc C function, the semantics are identical). It is used to allocate	248	realloc C function, the semantics are identical). It is used to allocate
222	and free memory (no surprises here). If it returns zero when memory	249	and free memory (no surprises here). If it returns zero when memory
…		…
224	destructive action. The default is your system realloc function.	251	destructive action. The default is your system realloc function.
225	.Sp	252	.Sp
226	You could override this function in high-availability programs to, say,	253	You could override this function in high-availability programs to, say,
227	free some memory if it cannot allocate memory, to use a special allocator,	254	free some memory if it cannot allocate memory, to use a special allocator,
228	or even to sleep a while and retry until some memory is available.	255	or even to sleep a while and retry until some memory is available.
		256	.Sp
		257	Example: replace the libev allocator with one that waits a bit and then
		258	retries: better than mine).
		259	.Sp
		260	.Vb 6
		261	\& static void *
		262	\& persistent_realloc (void *ptr, long size)
		263	\& {
		264	\& for (;;)
		265	\& {
		266	\& void *newptr = realloc (ptr, size);
		267	.Ve
		268	.Sp
		269	.Vb 2
		270	\& if (newptr)
		271	\& return newptr;
		272	.Ve
		273	.Sp
		274	.Vb 3
		275	\& sleep (60);
		276	\& }
		277	\& }
		278	.Ve
		279	.Sp
		280	.Vb 2
		281	\& ...
		282	\& ev_set_allocator (persistent_realloc);
		283	.Ve
229	.IP "ev_set_syserr_cb (void (cb)(const char msg));" 4	284	.IP "ev_set_syserr_cb (void (cb)(const char msg));" 4
230	.IX Item "ev_set_syserr_cb (void (cb)(const char msg));"	285	.IX Item "ev_set_syserr_cb (void (cb)(const char msg));"
231	Set the callback function to call on a retryable syscall error (such	286	Set the callback function to call on a retryable syscall error (such
232	as failed select, poll, epoll_wait). The message is a printable string	287	as failed select, poll, epoll_wait). The message is a printable string
233	indicating the system call or subsystem causing the problem. If this	288	indicating the system call or subsystem causing the problem. If this
234	callback is set, then libev will expect it to remedy the sitution, no	289	callback is set, then libev will expect it to remedy the sitution, no
235	matter what, when it returns. That is, libev will generally retry the	290	matter what, when it returns. That is, libev will generally retry the
236	requested operation, or, if the condition doesn't go away, do bad stuff	291	requested operation, or, if the condition doesn't go away, do bad stuff
237	(such as abort).	292	(such as abort).
		293	.Sp
		294	Example: do the same thing as libev does internally:
		295	.Sp
		296	.Vb 6
		297	\& static void
		298	\& fatal_error (const char *msg)
		299	\& {
		300	\& perror (msg);
		301	\& abort ();
		302	\& }
		303	.Ve
		304	.Sp
		305	.Vb 2
		306	\& ...
		307	\& ev_set_syserr_cb (fatal_error);
		308	.Ve
238	.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"	309	.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"
239	.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"	310	.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"
240	An event loop is described by a \f(CW\(C`struct ev_loop \*(C'\fR. The library knows two	311	An event loop is described by a \f(CW\(C`struct ev_loop \*(C'\fR. The library knows two
241	types of such loops, the \fIdefault\fR loop, which supports signals and child	312	types of such loops, the \fIdefault\fR loop, which supports signals and child
242	events, and dynamically created loops which do not.	313	events, and dynamically created loops which do not.
…		…
376	.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"	447	.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
377	Similar to \f(CW\(C`ev_default_loop\(C'\fR, but always creates a new event loop that is	448	Similar to \f(CW\(C`ev_default_loop\(C'\fR, but always creates a new event loop that is
378	always distinct from the default loop. Unlike the default loop, it cannot	449	always distinct from the default loop. Unlike the default loop, it cannot
379	handle signal and child watchers, and attempts to do so will be greeted by	450	handle signal and child watchers, and attempts to do so will be greeted by
380	undefined behaviour (or a failed assertion if assertions are enabled).	451	undefined behaviour (or a failed assertion if assertions are enabled).
		452	.Sp
		453	Example: try to create a event loop that uses epoll and nothing else.
		454	.Sp
		455	.Vb 3
		456	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
		457	\& if (!epoller)
		458	\& fatal ("no epoll found here, maybe it hides under your chair");
		459	.Ve
381	.IP "ev_default_destroy ()" 4	460	.IP "ev_default_destroy ()" 4
382	.IX Item "ev_default_destroy ()"	461	.IX Item "ev_default_destroy ()"
383	Destroys the default loop again (frees all memory and kernel state	462	Destroys the default loop again (frees all memory and kernel state
384	etc.). This stops all registered event watchers (by not touching them in	463	etc.). None of the active event watchers will be stopped in the normal
385	any way whatsoever, although you cannot rely on this :).	464	sense, so e.g. \f(CW\(C`ev_is_active\(C'\fR might still return true. It is your
		465	responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
		466	calling this function, or cope with the fact afterwards (which is usually
		467	the easiest thing, youc na just ignore the watchers and/or \f(CW\(C`free ()\(C'\fR them
		468	for example).
386	.IP "ev_loop_destroy (loop)" 4	469	.IP "ev_loop_destroy (loop)" 4
387	.IX Item "ev_loop_destroy (loop)"	470	.IX Item "ev_loop_destroy (loop)"
388	Like \f(CW\(C`ev_default_destroy\(C'\fR, but destroys an event loop created by an	471	Like \f(CW\(C`ev_default_destroy\(C'\fR, but destroys an event loop created by an
389	earlier call to \f(CW\(C`ev_loop_new\(C'\fR.	472	earlier call to \f(CW\(C`ev_loop_new\(C'\fR.
390	.IP "ev_default_fork ()" 4	473	.IP "ev_default_fork ()" 4
…		…
419	Returns one of the \f(CW\(C`EVBACKEND_\*(C'\fR flags indicating the event backend in	502	Returns one of the \f(CW\(C`EVBACKEND_\*(C'\fR flags indicating the event backend in
420	use.	503	use.
421	.IP "ev_tstamp ev_now (loop)" 4	504	.IP "ev_tstamp ev_now (loop)" 4
422	.IX Item "ev_tstamp ev_now (loop)"	505	.IX Item "ev_tstamp ev_now (loop)"
423	Returns the current \(L"event loop time\(R", which is the time the event loop	506	Returns the current \(L"event loop time\(R", which is the time the event loop
424	got events and started processing them. This timestamp does not change	507	received events and started processing them. This timestamp does not
425	as long as callbacks are being processed, and this is also the base time	508	change as long as callbacks are being processed, and this is also the base
426	used for relative timers. You can treat it as the timestamp of the event	509	time used for relative timers. You can treat it as the timestamp of the
427	occuring (or more correctly, the mainloop finding out about it).	510	event occuring (or more correctly, libev finding out about it).
428	.IP "ev_loop (loop, int flags)" 4	511	.IP "ev_loop (loop, int flags)" 4
429	.IX Item "ev_loop (loop, int flags)"	512	.IX Item "ev_loop (loop, int flags)"
430	Finally, this is it, the event handler. This function usually is called	513	Finally, this is it, the event handler. This function usually is called
431	after you initialised all your watchers and you want to start handling	514	after you initialised all your watchers and you want to start handling
432	events.	515	events.
433	.Sp	516	.Sp
434	If the flags argument is specified as \f(CW0\fR, it will not return until	517	If the flags argument is specified as \f(CW0\fR, it will not return until
435	either no event watchers are active anymore or \f(CW\(C`ev_unloop\(C'\fR was called.	518	either no event watchers are active anymore or \f(CW\(C`ev_unloop\(C'\fR was called.
		519	.Sp
		520	Please note that an explicit \f(CW\(C`ev_unloop\(C'\fR is usually better than
		521	relying on all watchers to be stopped when deciding when a program has
		522	finished (especially in interactive programs), but having a program that
		523	automatically loops as long as it has to and no longer by virtue of
		524	relying on its watchers stopping correctly is a thing of beauty.
436	.Sp	525	.Sp
437	A flags value of \f(CW\(C`EVLOOP_NONBLOCK\(C'\fR will look for new events, will handle	526	A flags value of \f(CW\(C`EVLOOP_NONBLOCK\(C'\fR will look for new events, will handle
438	those events and any outstanding ones, but will not block your process in	527	those events and any outstanding ones, but will not block your process in
439	case there are no events and will return after one iteration of the loop.	528	case there are no events and will return after one iteration of the loop.
440	.Sp	529	.Sp
…		…
465	\& - Call all queued watchers in reverse order (i.e. check watchers first).	554	\& - Call all queued watchers in reverse order (i.e. check watchers first).
466	\& Signals and child watchers are implemented as I/O watchers, and will	555	\& Signals and child watchers are implemented as I/O watchers, and will
467	\& be handled here by queueing them when their watcher gets executed.	556	\& be handled here by queueing them when their watcher gets executed.
468	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	557	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
469	\& were used, return, otherwise continue with step *.	558	\& were used, return, otherwise continue with step *.
		559	.Ve
		560	.Sp
		561	Example: queue some jobs and then loop until no events are outsanding
		562	anymore.
		563	.Sp
		564	.Vb 4
		565	\& ... queue jobs here, make sure they register event watchers as long
		566	\& ... as they still have work to do (even an idle watcher will do..)
		567	\& ev_loop (my_loop, 0);
		568	\& ... jobs done. yeah!
470	.Ve	569	.Ve
471	.IP "ev_unloop (loop, how)" 4	570	.IP "ev_unloop (loop, how)" 4
472	.IX Item "ev_unloop (loop, how)"	571	.IX Item "ev_unloop (loop, how)"
473	Can be used to make a call to \f(CW\(C`ev_loop\(C'\fR return early (but only after it	572	Can be used to make a call to \f(CW\(C`ev_loop\(C'\fR return early (but only after it
474	has processed all outstanding events). The \f(CW\(C`how\(C'\fR argument must be either	573	has processed all outstanding events). The \f(CW\(C`how\(C'\fR argument must be either
…		…
488	example, libev itself uses this for its internal signal pipe: It is not	587	example, libev itself uses this for its internal signal pipe: It is not
489	visible to the libev user and should not keep \f(CW\(C`ev_loop\(C'\fR from exiting if	588	visible to the libev user and should not keep \f(CW\(C`ev_loop\(C'\fR from exiting if
490	no event watchers registered by it are active. It is also an excellent	589	no event watchers registered by it are active. It is also an excellent
491	way to do this for generic recurring timers or from within third-party	590	way to do this for generic recurring timers or from within third-party
492	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.	591	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
		592	.Sp
		593	Example: create a signal watcher, but keep it from keeping \f(CW\(C`ev_loop\(C'\fR
		594	running when nothing else is active.
		595	.Sp
		596	.Vb 4
		597	\& struct dv_signal exitsig;
		598	\& ev_signal_init (&exitsig, sig_cb, SIGINT);
		599	\& ev_signal_start (myloop, &exitsig);
		600	\& evf_unref (myloop);
		601	.Ve
		602	.Sp
		603	Example: for some weird reason, unregister the above signal handler again.
		604	.Sp
		605	.Vb 2
		606	\& ev_ref (myloop);
		607	\& ev_signal_stop (myloop, &exitsig);
		608	.Ve
493	.SH "ANATOMY OF A WATCHER"	609	.SH "ANATOMY OF A WATCHER"
494	.IX Header "ANATOMY OF A WATCHER"	610	.IX Header "ANATOMY OF A WATCHER"
495	A watcher is a structure that you create and register to record your	611	A watcher is a structure that you create and register to record your
496	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to	612	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
497	become readable, you would create an \f(CW\(C`ev_io\(C'\fR watcher for that:	613	become readable, you would create an \f(CW\(C`ev_io\(C'\fR watcher for that:
…		…
533	)\(C'\fR), and you can stop watching for events at any time by calling the	649	)\(C'\fR), and you can stop watching for events at any time by calling the
534	corresponding stop function (\f(CW\(C`ev_<type>_stop (loop, watcher )\*(C'\fR.	650	corresponding stop function (\f(CW\(C`ev_<type>_stop (loop, watcher )\*(C'\fR.
535	.PP	651	.PP
536	As long as your watcher is active (has been started but not stopped) you	652	As long as your watcher is active (has been started but not stopped) you
537	must not touch the values stored in it. Most specifically you must never	653	must not touch the values stored in it. Most specifically you must never
538	reinitialise it or call its set macro.	654	reinitialise it or call its \f(CW\(C`set\(C'\fR macro.
539	.PP
540	You can check whether an event is active by calling the \f(CW\*(C`ev_is_active
541	(watcher )\(C'\fR macro. To see whether an event is outstanding (but the
542	callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
543	(watcher )\(C'\fR macro.
544	.PP	655	.PP
545	Each and every callback receives the event loop pointer as first, the	656	Each and every callback receives the event loop pointer as first, the
546	registered watcher structure as second, and a bitset of received events as	657	registered watcher structure as second, and a bitset of received events as
547	third argument.	658	third argument.
548	.PP	659	.PP
…		…
606	Libev will usually signal a few \(L"dummy\(R" events together with an error,	717	Libev will usually signal a few \(L"dummy\(R" events together with an error,
607	for example it might indicate that a fd is readable or writable, and if	718	for example it might indicate that a fd is readable or writable, and if
608	your callbacks is well-written it can just attempt the operation and cope	719	your callbacks is well-written it can just attempt the operation and cope
609	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded	720	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
610	programs, though, so beware.	721	programs, though, so beware.
		722	.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
		723	.IX Subsection "GENERIC WATCHER FUNCTIONS"
		724	In the following description, \f(CW\(C`TYPE\(C'\fR stands for the watcher type,
		725	e.g. \f(CW\(C`timer\(C'\fR for \f(CW\(C`ev_timer\(C'\fR watchers and \f(CW\(C`io\(C'\fR for \f(CW\(C`ev_io\(C'\fR watchers.
		726	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
		727	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
		728	.IX Item "ev_init (ev_TYPE *watcher, callback)"
		729	This macro initialises the generic portion of a watcher. The contents
		730	of the watcher object can be arbitrary (so \f(CW\(C`malloc\(C'\fR will do). Only
		731	the generic parts of the watcher are initialised, you \fIneed\fR to call
		732	the type-specific \f(CW\(C`ev_TYPE_set\(C'\fR macro afterwards to initialise the
		733	type-specific parts. For each type there is also a \f(CW\(C`ev_TYPE_init\(C'\fR macro
		734	which rolls both calls into one.
		735	.Sp
		736	You can reinitialise a watcher at any time as long as it has been stopped
		737	(or never started) and there are no pending events outstanding.
		738	.Sp
		739	The callback is always of type \f(CW\(C`void ()(ev_loop loop, ev_TYPE watcher,
		740	int revents)\*(C'\fR.
		741	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
		742	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
		743	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
		744	This macro initialises the type-specific parts of a watcher. You need to
		745	call \f(CW\(C`ev_init\(C'\fR at least once before you call this macro, but you can
		746	call \f(CW\(C`ev_TYPE_set\(C'\fR any number of times. You must not, however, call this
		747	macro on a watcher that is active (it can be pending, however, which is a
		748	difference to the \f(CW\(C`ev_init\(C'\fR macro).
		749	.Sp
		750	Although some watcher types do not have type-specific arguments
		751	(e.g. \f(CW\(C`ev_prepare\(C'\fR) you still need to call its \f(CW\(C`set\(C'\fR macro.
		752	.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
		753	.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
		754	.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
		755	This convinience macro rolls both \f(CW\(C`ev_init\(C'\fR and \f(CW\(C`ev_TYPE_set\(C'\fR macro
		756	calls into a single call. This is the most convinient method to initialise
		757	a watcher. The same limitations apply, of course.
		758	.ie n .IP """ev_TYPE_start"" (loop , ev_TYPE watcher)" 4
		759	.el .IP "\f(CWev_TYPE_start\fR (loop , ev_TYPE watcher)" 4
		760	.IX Item "ev_TYPE_start (loop , ev_TYPE watcher)"
		761	Starts (activates) the given watcher. Only active watchers will receive
		762	events. If the watcher is already active nothing will happen.
		763	.ie n .IP """ev_TYPE_stop"" (loop , ev_TYPE watcher)" 4
		764	.el .IP "\f(CWev_TYPE_stop\fR (loop , ev_TYPE watcher)" 4
		765	.IX Item "ev_TYPE_stop (loop , ev_TYPE watcher)"
		766	Stops the given watcher again (if active) and clears the pending
		767	status. It is possible that stopped watchers are pending (for example,
		768	non-repeating timers are being stopped when they become pending), but
		769	\&\f(CW\(C`ev_TYPE_stop\(C'\fR ensures that the watcher is neither active nor pending. If
		770	you want to free or reuse the memory used by the watcher it is therefore a
		771	good idea to always call its \f(CW\(C`ev_TYPE_stop\(C'\fR function.
		772	.IP "bool ev_is_active (ev_TYPE *watcher)" 4
		773	.IX Item "bool ev_is_active (ev_TYPE *watcher)"
		774	Returns a true value iff the watcher is active (i.e. it has been started
		775	and not yet been stopped). As long as a watcher is active you must not modify
		776	it.
		777	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
		778	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
		779	Returns a true value iff the watcher is pending, (i.e. it has outstanding
		780	events but its callback has not yet been invoked). As long as a watcher
		781	is pending (but not active) you must not call an init function on it (but
		782	\&\f(CW\(C`ev_TYPE_set\(C'\fR is safe) and you must make sure the watcher is available to
		783	libev (e.g. you cnanot \f(CW\(C`free ()\(C'\fR it).
		784	.IP "callback = ev_cb (ev_TYPE *watcher)" 4
		785	.IX Item "callback = ev_cb (ev_TYPE *watcher)"
		786	Returns the callback currently set on the watcher.
		787	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
		788	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
		789	Change the callback. You can change the callback at virtually any time
		790	(modulo threads).
611	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"	791	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
612	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"	792	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
613	Each watcher has, by default, a member \f(CW\(C`void data\*(C'\fR that you can change	793	Each watcher has, by default, a member \f(CW\(C`void data\*(C'\fR that you can change
614	and read at any time, libev will completely ignore it. This can be used	794	and read at any time, libev will completely ignore it. This can be used
615	to associate arbitrary data with your watcher. If you need more data and	795	to associate arbitrary data with your watcher. If you need more data and
…		…
642	have been omitted....	822	have been omitted....
643	.SH "WATCHER TYPES"	823	.SH "WATCHER TYPES"
644	.IX Header "WATCHER TYPES"	824	.IX Header "WATCHER TYPES"
645	This section describes each watcher in detail, but will not repeat	825	This section describes each watcher in detail, but will not repeat
646	information given in the last section.	826	information given in the last section.
647	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable"	827	.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?"
648	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable"	828	.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?"
649	.IX Subsection "ev_io - is this file descriptor readable or writable"	829	.IX Subsection "ev_io - is this file descriptor readable or writable?"
650	I/O watchers check whether a file descriptor is readable or writable	830	I/O watchers check whether a file descriptor is readable or writable
651	in each iteration of the event loop (This behaviour is called	831	in each iteration of the event loop, or, more precisely, when reading
652	level-triggering because you keep receiving events as long as the	832	would not block the process and writing would at least be able to write
653	condition persists. Remember you can stop the watcher if you don't want to	833	some data. This behaviour is called level-triggering because you keep
654	act on the event and neither want to receive future events).	834	receiving events as long as the condition persists. Remember you can stop
		835	the watcher if you don't want to act on the event and neither want to
		836	receive future events.
655	.PP	837	.PP
656	In general you can register as many read and/or write event watchers per	838	In general you can register as many read and/or write event watchers per
657	fd as you want (as long as you don't confuse yourself). Setting all file	839	fd as you want (as long as you don't confuse yourself). Setting all file
658	descriptors to non-blocking mode is also usually a good idea (but not	840	descriptors to non-blocking mode is also usually a good idea (but not
659	required if you know what you are doing).	841	required if you know what you are doing).
660	.PP	842	.PP
661	You have to be careful with dup'ed file descriptors, though. Some backends	843	You have to be careful with dup'ed file descriptors, though. Some backends
662	(the linux epoll backend is a notable example) cannot handle dup'ed file	844	(the linux epoll backend is a notable example) cannot handle dup'ed file
663	descriptors correctly if you register interest in two or more fds pointing	845	descriptors correctly if you register interest in two or more fds pointing
664	to the same underlying file/socket etc. description (that is, they share	846	to the same underlying file/socket/etc. description (that is, they share
665	the same underlying \(L"file open\(R").	847	the same underlying \(L"file open\(R").
666	.PP	848	.PP
667	If you must do this, then force the use of a known-to-be-good backend	849	If you must do this, then force the use of a known-to-be-good backend
668	(at the time of this writing, this includes only \f(CW\(C`EVBACKEND_SELECT\(C'\fR and	850	(at the time of this writing, this includes only \f(CW\(C`EVBACKEND_SELECT\(C'\fR and
669	\&\f(CW\(C`EVBACKEND_POLL\(C'\fR).	851	\&\f(CW\(C`EVBACKEND_POLL\(C'\fR).
		852	.PP
		853	Another thing you have to watch out for is that it is quite easy to
		854	receive \(L"spurious\(R" readyness notifications, that is your callback might
		855	be called with \f(CW\(C`EV_READ\(C'\fR but a subsequent \f(CW\(C`read\(C'\fR(2) will actually block
		856	because there is no data. Not only are some backends known to create a
		857	lot of those (for example solaris ports), it is very easy to get into
		858	this situation even with a relatively standard program structure. Thus
		859	it is best to always use non-blocking I/O: An extra \f(CW\(C`read\(C'\fR(2) returning
		860	\&\f(CW\(C`EAGAIN\(C'\fR is far preferable to a program hanging until some data arrives.
		861	.PP
		862	If you cannot run the fd in non-blocking mode (for example you should not
		863	play around with an Xlib connection), then you have to seperately re-test
		864	wether a file descriptor is really ready with a known-to-be good interface
		865	such as poll (fortunately in our Xlib example, Xlib already does this on
		866	its own, so its quite safe to use).
670	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4	867	.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
671	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"	868	.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
672	.PD 0	869	.PD 0
673	.IP "ev_io_set (ev_io *, int fd, int events)" 4	870	.IP "ev_io_set (ev_io *, int fd, int events)" 4
674	.IX Item "ev_io_set (ev_io *, int fd, int events)"	871	.IX Item "ev_io_set (ev_io *, int fd, int events)"
675	.PD	872	.PD
676	Configures an \f(CW\(C`ev_io\(C'\fR watcher. The fd is the file descriptor to rceeive	873	Configures an \f(CW\(C`ev_io\(C'\fR watcher. The \f(CW\(C`fd\(C'\fR is the file descriptor to
677	events 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 \|	874	rceeive events for and events is either \f(CW\(C`EV_READ\(C'\fR, \f(CW\(C`EV_WRITE\(C'\fR or
678	EV_WRITE\*(C'\fR to receive the given events.	875	\&\f(CW\(C`EV_READ \| EV_WRITE\(C'\fR to receive the given events.
679	.Sp	876	.PP
680	Please note that most of the more scalable backend mechanisms (for example	877	Example: call \f(CW\(C`stdin_readable_cb\(C'\fR when \s-1STDIN_FILENO\s0 has become, well
681	epoll and solaris ports) can result in spurious readyness notifications	878	readable, but only once. Since it is likely line\-buffered, you could
682	for file descriptors, so you practically need to use non-blocking I/O (and	879	attempt to read a whole line in the callback:
683	treat callback invocation as hint only), or retest separately with a safe	880	.PP
684	interface before doing I/O (XLib can do this), or force the use of either	881	.Vb 6
685	\&\f(CW\(C`EVBACKEND_SELECT\(C'\fR or \f(CW\(C`EVBACKEND_POLL\(C'\fR, which don't suffer from this	882	\& static void
686	problem. Also note that it is quite easy to have your callback invoked	883	\& stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
687	when the readyness condition is no longer valid even when employing	884	\& {
688	typical ways of handling events, so its a good idea to use non-blocking	885	\& ev_io_stop (loop, w);
689	I/O unconditionally.	886	\& .. read from stdin here (or from w->fd) and haqndle any I/O errors
		887	\& }
		888	.Ve
		889	.PP
		890	.Vb 6
		891	\& ...
		892	\& struct ev_loop *loop = ev_default_init (0);
		893	\& struct ev_io stdin_readable;
		894	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		895	\& ev_io_start (loop, &stdin_readable);
		896	\& ev_loop (loop, 0);
		897	.Ve
690	.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"	898	.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
691	.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"	899	.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
692	.IX Subsection "ev_timer - relative and optionally recurring timeouts"	900	.IX Subsection "ev_timer - relative and optionally repeating timeouts"
693	Timer watchers are simple relative timers that generate an event after a	901	Timer watchers are simple relative timers that generate an event after a
694	given time, and optionally repeating in regular intervals after that.	902	given time, and optionally repeating in regular intervals after that.
695	.PP	903	.PP
696	The timers are based on real time, that is, if you register an event that	904	The timers are based on real time, that is, if you register an event that
697	times out after an hour and you reset your system clock to last years	905	times out after an hour and you reset your system clock to last years
…		…
744	seconds of inactivity on the socket. The easiest way to do this is to	952	seconds of inactivity on the socket. The easiest way to do this is to
745	configure an \f(CW\(C`ev_timer\(C'\fR with after=repeat=60 and calling ev_timer_again each	953	configure an \f(CW\(C`ev_timer\(C'\fR with after=repeat=60 and calling ev_timer_again each
746	time you successfully read or write some data. If you go into an idle	954	time you successfully read or write some data. If you go into an idle
747	state where you do not expect data to travel on the socket, you can stop	955	state where you do not expect data to travel on the socket, you can stop
748	the timer, and again will automatically restart it if need be.	956	the timer, and again will automatically restart it if need be.
		957	.PP
		958	Example: create a timer that fires after 60 seconds.
		959	.PP
		960	.Vb 5
		961	\& static void
		962	\& one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		963	\& {
		964	\& .. one minute over, w is actually stopped right here
		965	\& }
		966	.Ve
		967	.PP
		968	.Vb 3
		969	\& struct ev_timer mytimer;
		970	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		971	\& ev_timer_start (loop, &mytimer);
		972	.Ve
		973	.PP
		974	Example: create a timeout timer that times out after 10 seconds of
		975	inactivity.
		976	.PP
		977	.Vb 5
		978	\& static void
		979	\& timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		980	\& {
		981	\& .. ten seconds without any activity
		982	\& }
		983	.Ve
		984	.PP
		985	.Vb 4
		986	\& struct ev_timer mytimer;
		987	\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		988	\& ev_timer_again (&mytimer); /* start timer */
		989	\& ev_loop (loop, 0);
		990	.Ve
		991	.PP
		992	.Vb 3
		993	\& // and in some piece of code that gets executed on any "activity":
		994	\& // reset the timeout to start ticking again at 10 seconds
		995	\& ev_timer_again (&mytimer);
		996	.Ve
749	.ie n .Sh """ev_periodic"" \- to cron or not to cron"	997	.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
750	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron"	998	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
751	.IX Subsection "ev_periodic - to cron or not to cron"	999	.IX Subsection "ev_periodic - to cron or not to cron?"
752	Periodic watchers are also timers of a kind, but they are very versatile	1000	Periodic watchers are also timers of a kind, but they are very versatile
753	(and unfortunately a bit complex).	1001	(and unfortunately a bit complex).
754	.PP	1002	.PP
755	Unlike \f(CW\(C`ev_timer\(C'\fR's, they are not based on real time (or relative time)	1003	Unlike \f(CW\(C`ev_timer\(C'\fR's, they are not based on real time (or relative time)
756	but on wallclock time (absolute time). You can tell a periodic watcher	1004	but on wallclock time (absolute time). You can tell a periodic watcher
757	to trigger \(L"at\(R" some specific point in time. For example, if you tell a	1005	to trigger \(L"at\(R" some specific point in time. For example, if you tell a
758	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1006	periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
759	+ 10.>) and then reset your system clock to the last year, then it will	1007	+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
760	take a year to trigger the event (unlike an \f(CW\(C`ev_timer\(C'\fR, which would trigger	1008	take a year to trigger the event (unlike an \f(CW\(C`ev_timer\(C'\fR, which would trigger
761	roughly 10 seconds later and of course not if you reset your system time	1009	roughly 10 seconds later and of course not if you reset your system time
762	again).	1010	again).
763	.PP	1011	.PP
764	They can also be used to implement vastly more complex timers, such as	1012	They can also be used to implement vastly more complex timers, such as
…		…
845	.IX Item "ev_periodic_again (loop, ev_periodic *)"	1093	.IX Item "ev_periodic_again (loop, ev_periodic *)"
846	Simply stops and restarts the periodic watcher again. This is only useful	1094	Simply stops and restarts the periodic watcher again. This is only useful
847	when you changed some parameters or the reschedule callback would return	1095	when you changed some parameters or the reschedule callback would return
848	a different time than the last time it was called (e.g. in a crond like	1096	a different time than the last time it was called (e.g. in a crond like
849	program when the crontabs have changed).	1097	program when the crontabs have changed).
		1098	.PP
		1099	Example: call a callback every hour, or, more precisely, whenever the
		1100	system clock is divisible by 3600. The callback invocation times have
		1101	potentially a lot of jittering, but good long-term stability.
		1102	.PP
		1103	.Vb 5
		1104	\& static void
		1105	\& clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		1106	\& {
		1107	\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
		1108	\& }
		1109	.Ve
		1110	.PP
		1111	.Vb 3
		1112	\& struct ev_periodic hourly_tick;
		1113	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		1114	\& ev_periodic_start (loop, &hourly_tick);
		1115	.Ve
		1116	.PP
		1117	Example: the same as above, but use a reschedule callback to do it:
		1118	.PP
		1119	.Vb 1
		1120	\& #include <math.h>
		1121	.Ve
		1122	.PP
		1123	.Vb 5
		1124	\& static ev_tstamp
		1125	\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		1126	\& {
		1127	\& return fmod (now, 3600.) + 3600.;
		1128	\& }
		1129	.Ve
		1130	.PP
		1131	.Vb 1
		1132	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1133	.Ve
		1134	.PP
		1135	Example: call a callback every hour, starting now:
		1136	.PP
		1137	.Vb 4
		1138	\& struct ev_periodic hourly_tick;
		1139	\& ev_periodic_init (&hourly_tick, clock_cb,
		1140	\& fmod (ev_now (loop), 3600.), 3600., 0);
		1141	\& ev_periodic_start (loop, &hourly_tick);
		1142	.Ve
850	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled"	1143	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
851	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled"	1144	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
852	.IX Subsection "ev_signal - signal me when a signal gets signalled"	1145	.IX Subsection "ev_signal - signal me when a signal gets signalled!"
853	Signal watchers will trigger an event when the process receives a specific	1146	Signal watchers will trigger an event when the process receives a specific
854	signal one or more times. Even though signals are very asynchronous, libev	1147	signal one or more times. Even though signals are very asynchronous, libev
855	will try it's best to deliver signals synchronously, i.e. as part of the	1148	will try it's best to deliver signals synchronously, i.e. as part of the
856	normal event processing, like any other event.	1149	normal event processing, like any other event.
857	.PP	1150	.PP
…		…
867	.IP "ev_signal_set (ev_signal *, int signum)" 4	1160	.IP "ev_signal_set (ev_signal *, int signum)" 4
868	.IX Item "ev_signal_set (ev_signal *, int signum)"	1161	.IX Item "ev_signal_set (ev_signal *, int signum)"
869	.PD	1162	.PD
870	Configures the watcher to trigger on the given signal number (usually one	1163	Configures the watcher to trigger on the given signal number (usually one
871	of the \f(CW\(C`SIGxxx\(C'\fR constants).	1164	of the \f(CW\(C`SIGxxx\(C'\fR constants).
872	.ie n .Sh """ev_child"" \- wait for pid status changes"	1165	.ie n .Sh """ev_child"" \- watch out for process status changes"
873	.el .Sh "\f(CWev_child\fP \- wait for pid status changes"	1166	.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
874	.IX Subsection "ev_child - wait for pid status changes"	1167	.IX Subsection "ev_child - watch out for process status changes"
875	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to	1168	Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
876	some child status changes (most typically when a child of yours dies).	1169	some child status changes (most typically when a child of yours dies).
877	.IP "ev_child_init (ev_child *, callback, int pid)" 4	1170	.IP "ev_child_init (ev_child *, callback, int pid)" 4
878	.IX Item "ev_child_init (ev_child *, callback, int pid)"	1171	.IX Item "ev_child_init (ev_child *, callback, int pid)"
879	.PD 0	1172	.PD 0
…		…
884	\&\fIany\fR process if \f(CW\(C`pid\(C'\fR is specified as \f(CW0\fR). The callback can look	1177	\&\fIany\fR process if \f(CW\(C`pid\(C'\fR is specified as \f(CW0\fR). The callback can look
885	at the \f(CW\(C`rstatus\(C'\fR member of the \f(CW\(C`ev_child\(C'\fR watcher structure to see	1178	at the \f(CW\(C`rstatus\(C'\fR member of the \f(CW\(C`ev_child\(C'\fR watcher structure to see
886	the status word (use the macros from \f(CW\(C`sys/wait.h\(C'\fR and see your systems	1179	the status word (use the macros from \f(CW\(C`sys/wait.h\(C'\fR and see your systems
887	\&\f(CW\(C`waitpid\(C'\fR documentation). The \f(CW\(C`rpid\(C'\fR member contains the pid of the	1180	\&\f(CW\(C`waitpid\(C'\fR documentation). The \f(CW\(C`rpid\(C'\fR member contains the pid of the
888	process causing the status change.	1181	process causing the status change.
		1182	.PP
		1183	Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
		1184	.PP
		1185	.Vb 5
		1186	\& static void
		1187	\& sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1188	\& {
		1189	\& ev_unloop (loop, EVUNLOOP_ALL);
		1190	\& }
		1191	.Ve
		1192	.PP
		1193	.Vb 3
		1194	\& struct ev_signal signal_watcher;
		1195	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1196	\& ev_signal_start (loop, &sigint_cb);
		1197	.Ve
889	.ie n .Sh """ev_idle"" \- when you've got nothing better to do"	1198	.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
890	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do"	1199	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
891	.IX Subsection "ev_idle - when you've got nothing better to do"	1200	.IX Subsection "ev_idle - when you've got nothing better to do..."
892	Idle watchers trigger events when there are no other events are pending	1201	Idle watchers trigger events when there are no other events are pending
893	(prepare, check and other idle watchers do not count). That is, as long	1202	(prepare, check and other idle watchers do not count). That is, as long
894	as your process is busy handling sockets or timeouts (or even signals,	1203	as your process is busy handling sockets or timeouts (or even signals,
895	imagine) it will not be triggered. But when your process is idle all idle	1204	imagine) it will not be triggered. But when your process is idle all idle
896	watchers are being called again and again, once per event loop iteration \-	1205	watchers are being called again and again, once per event loop iteration \-
…		…
907	.IP "ev_idle_init (ev_signal *, callback)" 4	1216	.IP "ev_idle_init (ev_signal *, callback)" 4
908	.IX Item "ev_idle_init (ev_signal *, callback)"	1217	.IX Item "ev_idle_init (ev_signal *, callback)"
909	Initialises and configures the idle watcher \- it has no parameters of any	1218	Initialises and configures the idle watcher \- it has no parameters of any
910	kind. There is a \f(CW\(C`ev_idle_set\(C'\fR macro, but using it is utterly pointless,	1219	kind. There is a \f(CW\(C`ev_idle_set\(C'\fR macro, but using it is utterly pointless,
911	believe me.	1220	believe me.
		1221	.PP
		1222	Example: dynamically allocate an \f(CW\(C`ev_idle\(C'\fR, start it, and in the
		1223	callback, free it. Alos, use no error checking, as usual.
		1224	.PP
		1225	.Vb 7
		1226	\& static void
		1227	\& idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1228	\& {
		1229	\& free (w);
		1230	\& // now do something you wanted to do when the program has
		1231	\& // no longer asnything immediate to do.
		1232	\& }
		1233	.Ve
		1234	.PP
		1235	.Vb 3
		1236	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1237	\& ev_idle_init (idle_watcher, idle_cb);
		1238	\& ev_idle_start (loop, idle_cb);
		1239	.Ve
912	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop"	1240	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
913	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop"	1241	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
914	.IX Subsection "ev_prepare and ev_check - customise your event loop"	1242	.IX Subsection "ev_prepare and ev_check - customise your event loop!"
915	Prepare and check watchers are usually (but not always) used in tandem:	1243	Prepare and check watchers are usually (but not always) used in tandem:
916	prepare watchers get invoked before the process blocks and check watchers	1244	prepare watchers get invoked before the process blocks and check watchers
917	afterwards.	1245	afterwards.
918	.PP	1246	.PP
		1247	You \fImust not\fR call \f(CW\(C`ev_loop\(C'\fR or similar functions that enter
		1248	the current event loop from either \f(CW\(C`ev_prepare\(C'\fR or \f(CW\(C`ev_check\(C'\fR
		1249	watchers. Other loops than the current one are fine, however. The
		1250	rationale behind this is that you do not need to check for recursion in
		1251	those watchers, i.e. the sequence will always be \f(CW\(C`ev_prepare\(C'\fR, blocking,
		1252	\&\f(CW\(C`ev_check\(C'\fR so if you have one watcher of each kind they will always be
		1253	called in pairs bracketing the blocking call.
		1254	.PP
919	Their main purpose is to integrate other event mechanisms into libev. This	1255	Their main purpose is to integrate other event mechanisms into libev and
920	could be used, for example, to track variable changes, implement your own	1256	their use is somewhat advanced. This could be used, for example, to track
921	watchers, integrate net-snmp or a coroutine library and lots more.	1257	variable changes, implement your own watchers, integrate net-snmp or a
		1258	coroutine library and lots more. They are also occasionally useful if
		1259	you cache some data and want to flush it before blocking (for example,
		1260	in X programs you might want to do an \f(CW\(C`XFlush ()\(C'\fR in an \f(CW\(C`ev_prepare\(C'\fR
		1261	watcher).
922	.PP	1262	.PP
923	This is done by examining in each prepare call which file descriptors need	1263	This is done by examining in each prepare call which file descriptors need
924	to be watched by the other library, registering \f(CW\(C`ev_io\(C'\fR watchers for	1264	to be watched by the other library, registering \f(CW\(C`ev_io\(C'\fR watchers for
925	them and starting an \f(CW\(C`ev_timer\(C'\fR watcher for any timeouts (many libraries	1265	them and starting an \f(CW\(C`ev_timer\(C'\fR watcher for any timeouts (many libraries
926	provide just this functionality). Then, in the check watcher you check for	1266	provide just this functionality). Then, in the check watcher you check for
…		…
944	.IX Item "ev_check_init (ev_check *, callback)"	1284	.IX Item "ev_check_init (ev_check *, callback)"
945	.PD	1285	.PD
946	Initialises and configures the prepare or check watcher \- they have no	1286	Initialises and configures the prepare or check watcher \- they have no
947	parameters of any kind. There are \f(CW\(C`ev_prepare_set\(C'\fR and \f(CW\(C`ev_check_set\(C'\fR	1287	parameters of any kind. There are \f(CW\(C`ev_prepare_set\(C'\fR and \f(CW\(C`ev_check_set\(C'\fR
948	macros, but using them is utterly, utterly and completely pointless.	1288	macros, but using them is utterly, utterly and completely pointless.
		1289	.PP
		1290	Example: To include a library such as adns, you would add \s-1IO\s0 watchers
		1291	and a timeout watcher in a prepare handler, as required by libadns, and
		1292	in a check watcher, destroy them and call into libadns. What follows is
		1293	pseudo-code only of course:
		1294	.PP
		1295	.Vb 2
		1296	\& static ev_io iow [nfd];
		1297	\& static ev_timer tw;
		1298	.Ve
		1299	.PP
		1300	.Vb 8
		1301	\& static void
		1302	\& io_cb (ev_loop loop, ev_io w, int revents)
		1303	\& {
		1304	\& // set the relevant poll flags
		1305	\& struct pollfd fd = (struct pollfd )w->data;
		1306	\& if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1307	\& if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1308	\& }
		1309	.Ve
		1310	.PP
		1311	.Vb 7
		1312	\& // create io watchers for each fd and a timer before blocking
		1313	\& static void
		1314	\& adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1315	\& {
		1316	\& int timeout = 3600000;truct pollfd fds [nfd];
		1317	\& // actual code will need to loop here and realloc etc.
		1318	\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1319	.Ve
		1320	.PP
		1321	.Vb 3
		1322	\& /* the callback is illegal, but won't be called as we stop during check */
		1323	\& ev_timer_init (&tw, 0, timeout * 1e-3);
		1324	\& ev_timer_start (loop, &tw);
		1325	.Ve
		1326	.PP
		1327	.Vb 6
		1328	\& // create on ev_io per pollfd
		1329	\& for (int i = 0; i < nfd; ++i)
		1330	\& {
		1331	\& ev_io_init (iow + i, io_cb, fds [i].fd,
		1332	\& ((fds [i].events & POLLIN ? EV_READ : 0)
		1333	\& \| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1334	.Ve
		1335	.PP
		1336	.Vb 5
		1337	\& fds [i].revents = 0;
		1338	\& iow [i].data = fds + i;
		1339	\& ev_io_start (loop, iow + i);
		1340	\& }
		1341	\& }
		1342	.Ve
		1343	.PP
		1344	.Vb 5
		1345	\& // stop all watchers after blocking
		1346	\& static void
		1347	\& adns_check_cb (ev_loop loop, ev_check w, int revents)
		1348	\& {
		1349	\& ev_timer_stop (loop, &tw);
		1350	.Ve
		1351	.PP
		1352	.Vb 2
		1353	\& for (int i = 0; i < nfd; ++i)
		1354	\& ev_io_stop (loop, iow + i);
		1355	.Ve
		1356	.PP
		1357	.Vb 2
		1358	\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1359	\& }
		1360	.Ve
		1361	.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
		1362	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
		1363	.IX Subsection "ev_embed - when one backend isn't enough..."
		1364	This is a rather advanced watcher type that lets you embed one event loop
		1365	into another (currently only \f(CW\(C`ev_io\(C'\fR events are supported in the embedded
		1366	loop, other types of watchers might be handled in a delayed or incorrect
		1367	fashion and must not be used).
		1368	.PP
		1369	There are primarily two reasons you would want that: work around bugs and
		1370	prioritise I/O.
		1371	.PP
		1372	As an example for a bug workaround, the kqueue backend might only support
		1373	sockets on some platform, so it is unusable as generic backend, but you
		1374	still want to make use of it because you have many sockets and it scales
		1375	so nicely. In this case, you would create a kqueue-based loop and embed it
		1376	into your default loop (which might use e.g. poll). Overall operation will
		1377	be a bit slower because first libev has to poll and then call kevent, but
		1378	at least you can use both at what they are best.
		1379	.PP
		1380	As for prioritising I/O: rarely you have the case where some fds have
		1381	to be watched and handled very quickly (with low latency), and even
		1382	priorities and idle watchers might have too much overhead. In this case
		1383	you would put all the high priority stuff in one loop and all the rest in
		1384	a second one, and embed the second one in the first.
		1385	.PP
		1386	As long as the watcher is active, the callback will be invoked every time
		1387	there might be events pending in the embedded loop. The callback must then
		1388	call \f(CW\(C`ev_embed_sweep (mainloop, watcher)\(C'\fR to make a single sweep and invoke
		1389	their callbacks (you could also start an idle watcher to give the embedded
		1390	loop strictly lower priority for example). You can also set the callback
		1391	to \f(CW0\fR, in which case the embed watcher will automatically execute the
		1392	embedded loop sweep.
		1393	.PP
		1394	As long as the watcher is started it will automatically handle events. The
		1395	callback will be invoked whenever some events have been handled. You can
		1396	set the callback to \f(CW0\fR to avoid having to specify one if you are not
		1397	interested in that.
		1398	.PP
		1399	Also, there have not currently been made special provisions for forking:
		1400	when you fork, you not only have to call \f(CW\(C`ev_loop_fork\(C'\fR on both loops,
		1401	but you will also have to stop and restart any \f(CW\(C`ev_embed\(C'\fR watchers
		1402	yourself.
		1403	.PP
		1404	Unfortunately, not all backends are embeddable, only the ones returned by
		1405	\&\f(CW\(C`ev_embeddable_backends\(C'\fR are, which, unfortunately, does not include any
		1406	portable one.
		1407	.PP
		1408	So when you want to use this feature you will always have to be prepared
		1409	that you cannot get an embeddable loop. The recommended way to get around
		1410	this is to have a separate variables for your embeddable loop, try to
		1411	create it, and if that fails, use the normal loop for everything:
		1412	.PP
		1413	.Vb 3
		1414	\& struct ev_loop *loop_hi = ev_default_init (0);
		1415	\& struct ev_loop *loop_lo = 0;
		1416	\& struct ev_embed embed;
		1417	.Ve
		1418	.PP
		1419	.Vb 5
		1420	\& // see if there is a chance of getting one that works
		1421	\& // (remember that a flags value of 0 means autodetection)
		1422	\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1423	\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1424	\& : 0;
		1425	.Ve
		1426	.PP
		1427	.Vb 8
		1428	\& // if we got one, then embed it, otherwise default to loop_hi
		1429	\& if (loop_lo)
		1430	\& {
		1431	\& ev_embed_init (&embed, 0, loop_lo);
		1432	\& ev_embed_start (loop_hi, &embed);
		1433	\& }
		1434	\& else
		1435	\& loop_lo = loop_hi;
		1436	.Ve
		1437	.IP "ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)" 4
		1438	.IX Item "ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)"
		1439	.PD 0
		1440	.IP "ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)" 4
		1441	.IX Item "ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)"
		1442	.PD
		1443	Configures the watcher to embed the given loop, which must be
		1444	embeddable. If the callback is \f(CW0\fR, then \f(CW\(C`ev_embed_sweep\(C'\fR will be
		1445	invoked automatically, otherwise it is the responsibility of the callback
		1446	to invoke it (it will continue to be called until the sweep has been done,
		1447	if you do not want thta, you need to temporarily stop the embed watcher).
		1448	.IP "ev_embed_sweep (loop, ev_embed *)" 4
		1449	.IX Item "ev_embed_sweep (loop, ev_embed *)"
		1450	Make a single, non-blocking sweep over the embedded loop. This works
		1451	similarly to \f(CW\(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\(C'\fR, but in the most
		1452	apropriate way for embedded loops.
949	.SH "OTHER FUNCTIONS"	1453	.SH "OTHER FUNCTIONS"
950	.IX Header "OTHER FUNCTIONS"	1454	.IX Header "OTHER FUNCTIONS"
951	There are some other functions of possible interest. Described. Here. Now.	1455	There are some other functions of possible interest. Described. Here. Now.
952	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4	1456	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
953	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"	1457	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
…		…
982	.Ve	1486	.Ve
983	.Sp	1487	.Sp
984	.Vb 1	1488	.Vb 1
985	\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1489	\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
986	.Ve	1490	.Ve
987	.IP "ev_feed_event (loop, watcher, int events)" 4	1491	.IP "ev_feed_event (ev_loop , watcher , int revents)" 4
988	.IX Item "ev_feed_event (loop, watcher, int events)"	1492	.IX Item "ev_feed_event (ev_loop , watcher , int revents)"
989	Feeds the given event set into the event loop, as if the specified event	1493	Feeds the given event set into the event loop, as if the specified event
990	had happened for the specified watcher (which must be a pointer to an	1494	had happened for the specified watcher (which must be a pointer to an
991	initialised but not necessarily started event watcher).	1495	initialised but not necessarily started event watcher).
992	.IP "ev_feed_fd_event (loop, int fd, int revents)" 4	1496	.IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4
993	.IX Item "ev_feed_fd_event (loop, int fd, int revents)"	1497	.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)"
994	Feed an event on the given fd, as if a file descriptor backend detected	1498	Feed an event on the given fd, as if a file descriptor backend detected
995	the given events it.	1499	the given events it.
996	.IP "ev_feed_signal_event (loop, int signum)" 4	1500	.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
997	.IX Item "ev_feed_signal_event (loop, int signum)"	1501	.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
998	Feed an event as if the given signal occured (loop must be the default loop!).	1502	Feed an event as if the given signal occured (\f(CW\(C`loop\(C'\fR must be the default
		1503	loop!).
999	.SH "LIBEVENT EMULATION"	1504	.SH "LIBEVENT EMULATION"
1000	.IX Header "LIBEVENT EMULATION"	1505	.IX Header "LIBEVENT EMULATION"
1001	Libev offers a compatibility emulation layer for libevent. It cannot	1506	Libev offers a compatibility emulation layer for libevent. It cannot
1002	emulate the internals of libevent, so here are some usage hints:	1507	emulate the internals of libevent, so here are some usage hints:
1003	.IP "* Use it by including <event.h>, as usual." 4	1508	.IP "* Use it by including <event.h>, as usual." 4
…		…
1014	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4	1519	.IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4
1015	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."	1520	.IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library."
1016	.PD	1521	.PD
1017	.SH "\*(C+ SUPPORT"	1522	.SH "\*(C+ SUPPORT"
1018	.IX Header " SUPPORT"	1523	.IX Header " SUPPORT"
1019	\&\s-1TBD\s0.	1524	Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
		1525	you to use some convinience methods to start/stop watchers and also change
		1526	the callback model to a model using method callbacks on objects.
		1527	.PP
		1528	To use it,
		1529	.PP
		1530	.Vb 1
		1531	\& #include <ev++.h>
		1532	.Ve
		1533	.PP
		1534	(it is not installed by default). This automatically includes \fIev.h\fR
		1535	and puts all of its definitions (many of them macros) into the global
		1536	namespace. All \(C+ specific things are put into the \f(CW\(C`ev\*(C'\fR namespace.
		1537	.PP
		1538	It should support all the same embedding options as \fIev.h\fR, most notably
		1539	\&\f(CW\(C`EV_MULTIPLICITY\(C'\fR.
		1540	.PP
		1541	Here is a list of things available in the \f(CW\(C`ev\(C'\fR namespace:
		1542	.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
		1543	.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
		1544	.IX Item "ev::READ, ev::WRITE etc."
		1545	These are just enum values with the same values as the \f(CW\(C`EV_READ\(C'\fR etc.
		1546	macros from \fIev.h\fR.
		1547	.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4
		1548	.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
		1549	.IX Item "ev::tstamp, ev::now"
		1550	Aliases to the same types/functions as with the \f(CW\(C`ev_\(C'\fR prefix.
		1551	.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
		1552	.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
		1553	.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
		1554	For each \f(CW\(C`ev_TYPE\(C'\fR watcher in \fIev.h\fR there is a corresponding class of
		1555	the same name in the \f(CW\(C`ev\(C'\fR namespace, with the exception of \f(CW\(C`ev_signal\(C'\fR
		1556	which is called \f(CW\(C`ev::sig\(C'\fR to avoid clashes with the \f(CW\(C`signal\(C'\fR macro
		1557	defines by many implementations.
		1558	.Sp
		1559	All of those classes have these methods:
		1560	.RS 4
		1561	.IP "ev::TYPE::TYPE (object , object::method )" 4
		1562	.IX Item "ev::TYPE::TYPE (object , object::method )"
		1563	.PD 0
		1564	.IP "ev::TYPE::TYPE (object , object::method , struct ev_loop *)" 4
		1565	.IX Item "ev::TYPE::TYPE (object , object::method , struct ev_loop *)"
		1566	.IP "ev::TYPE::~TYPE" 4
		1567	.IX Item "ev::TYPE::~TYPE"
		1568	.PD
		1569	The constructor takes a pointer to an object and a method pointer to
		1570	the event handler callback to call in this class. The constructor calls
		1571	\&\f(CW\(C`ev_init\(C'\fR for you, which means you have to call the \f(CW\(C`set\(C'\fR method
		1572	before starting it. If you do not specify a loop then the constructor
		1573	automatically associates the default loop with this watcher.
		1574	.Sp
		1575	The destructor automatically stops the watcher if it is active.
		1576	.IP "w\->set (struct ev_loop *)" 4
		1577	.IX Item "w->set (struct ev_loop *)"
		1578	Associates a different \f(CW\(C`struct ev_loop\(C'\fR with this watcher. You can only
		1579	do this when the watcher is inactive (and not pending either).
		1580	.IP "w\->set ([args])" 4
		1581	.IX Item "w->set ([args])"
		1582	Basically the same as \f(CW\(C`ev_TYPE_set\(C'\fR, with the same args. Must be
		1583	called at least once. Unlike the C counterpart, an active watcher gets
		1584	automatically stopped and restarted.
		1585	.IP "w\->start ()" 4
		1586	.IX Item "w->start ()"
		1587	Starts the watcher. Note that there is no \f(CW\(C`loop\(C'\fR argument as the
		1588	constructor already takes the loop.
		1589	.IP "w\->stop ()" 4
		1590	.IX Item "w->stop ()"
		1591	Stops the watcher if it is active. Again, no \f(CW\(C`loop\(C'\fR argument.
		1592	.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
		1593	.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
		1594	.IX Item "w->again () ev::timer, ev::periodic only"
		1595	For \f(CW\(C`ev::timer\(C'\fR and \f(CW\(C`ev::periodic\(C'\fR, this invokes the corresponding
		1596	\&\f(CW\(C`ev_TYPE_again\(C'\fR function.
		1597	.ie n .IP "w\->sweep () ""ev::embed"" only" 4
		1598	.el .IP "w\->sweep () \f(CWev::embed\fR only" 4
		1599	.IX Item "w->sweep () ev::embed only"
		1600	Invokes \f(CW\(C`ev_embed_sweep\(C'\fR.
		1601	.RE
		1602	.RS 4
		1603	.RE
		1604	.PP
		1605	Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
		1606	the constructor.
		1607	.PP
		1608	.Vb 4
		1609	\& class myclass
		1610	\& {
		1611	\& ev_io io; void io_cb (ev::io &w, int revents);
		1612	\& ev_idle idle void idle_cb (ev::idle &w, int revents);
		1613	.Ve
		1614	.PP
		1615	.Vb 2
		1616	\& myclass ();
		1617	\& }
		1618	.Ve
		1619	.PP
		1620	.Vb 6
		1621	\& myclass::myclass (int fd)
		1622	\& : io (this, &myclass::io_cb),
		1623	\& idle (this, &myclass::idle_cb)
		1624	\& {
		1625	\& io.start (fd, ev::READ);
		1626	\& }
		1627	.Ve
		1628	.SH "EMBEDDING"
		1629	.IX Header "EMBEDDING"
		1630	Libev can (and often is) directly embedded into host
		1631	applications. Examples of applications that embed it include the Deliantra
		1632	Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
		1633	and rxvt\-unicode.
		1634	.PP
		1635	The goal is to enable you to just copy the neecssary files into your
		1636	source directory without having to change even a single line in them, so
		1637	you can easily upgrade by simply copying (or having a checked-out copy of
		1638	libev somewhere in your source tree).
		1639	.Sh "\s-1FILESETS\s0"
		1640	.IX Subsection "FILESETS"
		1641	Depending on what features you need you need to include one or more sets of files
		1642	in your app.
		1643	.PP
		1644	\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
		1645	.IX Subsection "CORE EVENT LOOP"
		1646	.PP
		1647	To include only the libev core (all the \f(CW\(C`ev_\*(C'\fR functions), with manual
		1648	configuration (no autoconf):
		1649	.PP
		1650	.Vb 2
		1651	\& #define EV_STANDALONE 1
		1652	\& #include "ev.c"
		1653	.Ve
		1654	.PP
		1655	This will automatically include \fIev.h\fR, too, and should be done in a
		1656	single C source file only to provide the function implementations. To use
		1657	it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
		1658	done by writing a wrapper around \fIev.h\fR that you can include instead and
		1659	where you can put other configuration options):
		1660	.PP
		1661	.Vb 2
		1662	\& #define EV_STANDALONE 1
		1663	\& #include "ev.h"
		1664	.Ve
		1665	.PP
		1666	Both header files and implementation files can be compiled with a \*(C+
		1667	compiler (at least, thats a stated goal, and breakage will be treated
		1668	as a bug).
		1669	.PP
		1670	You need the following files in your source tree, or in a directory
		1671	in your include path (e.g. in libev/ when using \-Ilibev):
		1672	.PP
		1673	.Vb 4
		1674	\& ev.h
		1675	\& ev.c
		1676	\& ev_vars.h
		1677	\& ev_wrap.h
		1678	.Ve
		1679	.PP
		1680	.Vb 1
		1681	\& ev_win32.c required on win32 platforms only
		1682	.Ve
		1683	.PP
		1684	.Vb 5
		1685	\& ev_select.c only when select backend is enabled (which is by default)
		1686	\& ev_poll.c only when poll backend is enabled (disabled by default)
		1687	\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1688	\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1689	\& ev_port.c only when the solaris port backend is enabled (disabled by default)
		1690	.Ve
		1691	.PP
		1692	\&\fIev.c\fR includes the backend files directly when enabled, so you only need
		1693	to compile this single file.
		1694	.PP
		1695	\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR
		1696	.IX Subsection "LIBEVENT COMPATIBILITY API"
		1697	.PP
		1698	To include the libevent compatibility \s-1API\s0, also include:
		1699	.PP
		1700	.Vb 1
		1701	\& #include "event.c"
		1702	.Ve
		1703	.PP
		1704	in the file including \fIev.c\fR, and:
		1705	.PP
		1706	.Vb 1
		1707	\& #include "event.h"
		1708	.Ve
		1709	.PP
		1710	in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
		1711	.PP
		1712	You need the following additional files for this:
		1713	.PP
		1714	.Vb 2
		1715	\& event.h
		1716	\& event.c
		1717	.Ve
		1718	.PP
		1719	\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
		1720	.IX Subsection "AUTOCONF SUPPORT"
		1721	.PP
		1722	Instead of using \f(CW\(C`EV_STANDALONE=1\(C'\fR and providing your config in
		1723	whatever way you want, you can also \f(CW\(C`m4_include([libev.m4])\(C'\fR in your
		1724	\&\fIconfigure.ac\fR and leave \f(CW\(C`EV_STANDALONE\(C'\fR undefined. \fIev.c\fR will then
		1725	include \fIconfig.h\fR and configure itself accordingly.
		1726	.PP
		1727	For this of course you need the m4 file:
		1728	.PP
		1729	.Vb 1
		1730	\& libev.m4
		1731	.Ve
		1732	.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
		1733	.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
		1734	Libev can be configured via a variety of preprocessor symbols you have to define
		1735	before including any of its files. The default is not to build for multiplicity
		1736	and only include the select backend.
		1737	.IP "\s-1EV_STANDALONE\s0" 4
		1738	.IX Item "EV_STANDALONE"
		1739	Must always be \f(CW1\fR if you do not use autoconf configuration, which
		1740	keeps libev from including \fIconfig.h\fR, and it also defines dummy
		1741	implementations for some libevent functions (such as logging, which is not
		1742	supported). It will also not define any of the structs usually found in
		1743	\&\fIevent.h\fR that are not directly supported by the libev core alone.
		1744	.IP "\s-1EV_USE_MONOTONIC\s0" 4
		1745	.IX Item "EV_USE_MONOTONIC"
		1746	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		1747	monotonic clock option at both compiletime and runtime. Otherwise no use
		1748	of the monotonic clock option will be attempted. If you enable this, you
		1749	usually have to link against librt or something similar. Enabling it when
		1750	the functionality isn't available is safe, though, althoguh you have
		1751	to make sure you link against any libraries where the \f(CW\(C`clock_gettime\(C'\fR
		1752	function is hiding in (often \fI\-lrt\fR).
		1753	.IP "\s-1EV_USE_REALTIME\s0" 4
		1754	.IX Item "EV_USE_REALTIME"
		1755	If defined to be \f(CW1\fR, libev will try to detect the availability of the
		1756	realtime clock option at compiletime (and assume its availability at
		1757	runtime if successful). Otherwise no use of the realtime clock option will
		1758	be attempted. This effectively replaces \f(CW\(C`gettimeofday\(C'\fR by \f(CW\*(C`clock_get
		1759	(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries
		1760	in the description of \f(CW\(C`EV_USE_MONOTONIC\(C'\fR, though.
		1761	.IP "\s-1EV_USE_SELECT\s0" 4
		1762	.IX Item "EV_USE_SELECT"
		1763	If undefined or defined to be \f(CW1\fR, libev will compile in support for the
		1764	\&\f(CW\(C`select\(C'\fR(2) backend. No attempt at autodetection will be done: if no
		1765	other method takes over, select will be it. Otherwise the select backend
		1766	will not be compiled in.
		1767	.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
		1768	.IX Item "EV_SELECT_USE_FD_SET"
		1769	If defined to \f(CW1\fR, then the select backend will use the system \f(CW\(C`fd_set\(C'\fR
		1770	structure. This is useful if libev doesn't compile due to a missing
		1771	\&\f(CW\(C`NFDBITS\(C'\fR or \f(CW\(C`fd_mask\(C'\fR definition or it misguesses the bitset layout on
		1772	exotic systems. This usually limits the range of file descriptors to some
		1773	low limit such as 1024 or might have other limitations (winsocket only
		1774	allows 64 sockets). The \f(CW\(C`FD_SETSIZE\(C'\fR macro, set before compilation, might
		1775	influence the size of the \f(CW\(C`fd_set\(C'\fR used.
		1776	.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
		1777	.IX Item "EV_SELECT_IS_WINSOCKET"
		1778	When defined to \f(CW1\fR, the select backend will assume that
		1779	select/socket/connect etc. don't understand file descriptors but
		1780	wants osf handles on win32 (this is the case when the select to
		1781	be used is the winsock select). This means that it will call
		1782	\&\f(CW\(C`_get_osfhandle\(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise,
		1783	it is assumed that all these functions actually work on fds, even
		1784	on win32. Should not be defined on non\-win32 platforms.
		1785	.IP "\s-1EV_USE_POLL\s0" 4
		1786	.IX Item "EV_USE_POLL"
		1787	If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\(C`poll\(C'\fR(2)
		1788	backend. Otherwise it will be enabled on non\-win32 platforms. It
		1789	takes precedence over select.
		1790	.IP "\s-1EV_USE_EPOLL\s0" 4
		1791	.IX Item "EV_USE_EPOLL"
		1792	If defined to be \f(CW1\fR, libev will compile in support for the Linux
		1793	\&\f(CW\(C`epoll\(C'\fR(7) backend. Its availability will be detected at runtime,
		1794	otherwise another method will be used as fallback. This is the
		1795	preferred backend for GNU/Linux systems.
		1796	.IP "\s-1EV_USE_KQUEUE\s0" 4
		1797	.IX Item "EV_USE_KQUEUE"
		1798	If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style
		1799	\&\f(CW\(C`kqueue\(C'\fR(2) backend. Its actual availability will be detected at runtime,
		1800	otherwise another method will be used as fallback. This is the preferred
		1801	backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only
		1802	supports some types of fds correctly (the only platform we found that
		1803	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1804	not be used unless explicitly requested. The best way to use it is to find
		1805	out whether kqueue supports your type of fd properly and use an embedded
		1806	kqueue loop.
		1807	.IP "\s-1EV_USE_PORT\s0" 4
		1808	.IX Item "EV_USE_PORT"
		1809	If defined to be \f(CW1\fR, libev will compile in support for the Solaris
		1810	10 port style backend. Its availability will be detected at runtime,
		1811	otherwise another method will be used as fallback. This is the preferred
		1812	backend for Solaris 10 systems.
		1813	.IP "\s-1EV_USE_DEVPOLL\s0" 4
		1814	.IX Item "EV_USE_DEVPOLL"
		1815	reserved for future expansion, works like the \s-1USE\s0 symbols above.
		1816	.IP "\s-1EV_H\s0" 4
		1817	.IX Item "EV_H"
		1818	The name of the \fIev.h\fR header file used to include it. The default if
		1819	undefined is \f(CW\(C`<ev.h>\(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
		1820	can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
		1821	.IP "\s-1EV_CONFIG_H\s0" 4
		1822	.IX Item "EV_CONFIG_H"
		1823	If \f(CW\(C`EV_STANDALONE\(C'\fR isn't \f(CW1\fR, this variable can be used to override
		1824	\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
		1825	\&\f(CW\(C`EV_H\(C'\fR, above.
		1826	.IP "\s-1EV_EVENT_H\s0" 4
		1827	.IX Item "EV_EVENT_H"
		1828	Similarly to \f(CW\(C`EV_H\(C'\fR, this macro can be used to override \fIevent.c\fR's idea
		1829	of how the \fIevent.h\fR header can be found.
		1830	.IP "\s-1EV_PROTOTYPES\s0" 4
		1831	.IX Item "EV_PROTOTYPES"
		1832	If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
		1833	prototypes, but still define all the structs and other symbols. This is
		1834	occasionally useful if you want to provide your own wrapper functions
		1835	around libev functions.
		1836	.IP "\s-1EV_MULTIPLICITY\s0" 4
		1837	.IX Item "EV_MULTIPLICITY"
		1838	If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
		1839	will have the \f(CW\(C`struct ev_loop \*(C'\fR as first argument, and you can create
		1840	additional independent event loops. Otherwise there will be no support
		1841	for multiple event loops and there is no first event loop pointer
		1842	argument. Instead, all functions act on the single default loop.
		1843	.IP "\s-1EV_PERIODICS\s0" 4
		1844	.IX Item "EV_PERIODICS"
		1845	If undefined or defined to be \f(CW1\fR, then periodic timers are supported,
		1846	otherwise not. This saves a few kb of code.
		1847	.IP "\s-1EV_COMMON\s0" 4
		1848	.IX Item "EV_COMMON"
		1849	By default, all watchers have a \f(CW\(C`void data\*(C'\fR member. By redefining
		1850	this macro to a something else you can include more and other types of
		1851	members. You have to define it each time you include one of the files,
		1852	though, and it must be identical each time.
		1853	.Sp
		1854	For example, the perl \s-1EV\s0 module uses something like this:
		1855	.Sp
		1856	.Vb 3
		1857	\& #define EV_COMMON \e
		1858	\& SV self; / contains this struct */ \e
		1859	\& SV cb_sv, fh /* note no trailing ";" */
		1860	.Ve
		1861	.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
		1862	.IX Item "EV_CB_DECLARE (type)"
		1863	.PD 0
		1864	.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
		1865	.IX Item "EV_CB_INVOKE (watcher, revents)"
		1866	.IP "ev_set_cb (ev, cb)" 4
		1867	.IX Item "ev_set_cb (ev, cb)"
		1868	.PD
		1869	Can be used to change the callback member declaration in each watcher,
		1870	and the way callbacks are invoked and set. Must expand to a struct member
		1871	definition and a statement, respectively. See the \fIev.v\fR header file for
		1872	their default definitions. One possible use for overriding these is to
		1873	avoid the \f(CW\(C`struct ev_loop \*(C'\fR as first argument in all cases, or to use
		1874	method calls instead of plain function calls in \*(C+.
		1875	.Sh "\s-1EXAMPLES\s0"
		1876	.IX Subsection "EXAMPLES"
		1877	For a real-world example of a program the includes libev
		1878	verbatim, you can have a look at the \s-1EV\s0 perl module
		1879	(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		1880	the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
		1881	interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
		1882	will be compiled. It is pretty complex because it provides its own header
		1883	file.
		1884	.Sp
		1885	The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
		1886	that everybody includes and which overrides some autoconf choices:
		1887	.Sp
		1888	.Vb 4
		1889	\& #define EV_USE_POLL 0
		1890	\& #define EV_MULTIPLICITY 0
		1891	\& #define EV_PERIODICS 0
		1892	\& #define EV_CONFIG_H <config.h>
		1893	.Ve
		1894	.Sp
		1895	.Vb 1
		1896	\& #include "ev++.h"
		1897	.Ve
		1898	.Sp
		1899	And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
		1900	.Sp
		1901	.Vb 2
		1902	\& #include "ev_cpp.h"
		1903	\& #include "ev.c"
		1904	.Ve
1020	.SH "AUTHOR"	1905	.SH "AUTHOR"
1021	.IX Header "AUTHOR"	1906	.IX Header "AUTHOR"
1022	Marc Lehmann <libev@schmorp.de>.	1907	Marc Lehmann <libev@schmorp.de>.

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Comparing libev/ev.3 (file contents): Revision 1.8 by root, Fri Nov 23 15:26:08 2007 UTC vs. Revision 1.20 by root, Mon Nov 26 09:52:14 2007 UTC

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Comparing libev/ev.3 (file contents):
Revision 1.8 by root, Fri Nov 23 15:26:08 2007 UTC vs.
Revision 1.20 by root, Mon Nov 26 09:52:14 2007 UTC