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

Comparing libev/ev.pod (file contents):
Revision 1.1 by root, Mon Nov 12 07:58:13 2007 UTC vs.
Revision 1.33 by root, Fri Nov 23 15:26:08 2007 UTC

…		…
8		8
9	=head1 DESCRIPTION	9	=head1 DESCRIPTION
10		10
11	Libev is an event loop: you register interest in certain events (such as a	11	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	12	file descriptor being readable or a timeout occuring), and it will manage
13	these event sources and provide your program events.	13	these event sources and provide your program with events.
14		14
15	To do this, it must take more or less complete control over your process	15	To do this, it must take more or less complete control over your process
16	(or thread) by executing the I<event loop> handler, and will then	16	(or thread) by executing the I<event loop> handler, and will then
17	communicate events via a callback mechanism.	17	communicate events via a callback mechanism.
18		18
…		…
25		25
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	26	Libev supports select, poll, the linux-specific epoll and the bsd-specific
27	kqueue mechanisms for file descriptor events, relative timers, absolute	27	kqueue mechanisms for file descriptor events, relative timers, absolute
28	timers with customised rescheduling, signal events, process status change	28	timers with customised rescheduling, signal events, process status change
29	events (related to SIGCHLD), and event watchers dealing with the event	29	events (related to SIGCHLD), and event watchers dealing with the event
30	loop mechanism itself (idle, prepare and check watchers).	30	loop mechanism itself (idle, prepare and check watchers). It also is quite
		31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing
		32	it to libevent for example).
31		33
32	=head1 CONVENTIONS	34	=head1 CONVENTIONS
33		35
34	Libev is very configurable. In this manual the default configuration	36	Libev is very configurable. In this manual the default configuration
35	will be described, which supports multiple event loops. For more info	37	will be described, which supports multiple event loops. For more info
36	about various configuraiton options please have a look at the file	38	about various configuration options please have a look at the file
37	F<README.embed> in the libev distribution. If libev was configured without	39	F<README.embed> in the libev distribution. If libev was configured without
38	support for multiple event loops, then all functions taking an initial	40	support for multiple event loops, then all functions taking an initial
39	argument of name C<loop> (which is always of type C<struct ev_loop *>)	41	argument of name C<loop> (which is always of type C<struct ev_loop *>)
40	will not have this argument.	42	will not have this argument.
41		43
42	=head1 TIME AND OTHER GLOBAL FUNCTIONS	44	=head1 TIME REPRESENTATION
43		45
44	Libev represents time as a single floating point number. This type is	46	Libev represents time as a single floating point number, representing the
		47	(fractional) number of seconds since the (POSIX) epoch (somewhere near
		48	the beginning of 1970, details are complicated, don't ask). This type is
45	called C<ev_tstamp>, which is what you should use too. It usually aliases	49	called C<ev_tstamp>, which is what you should use too. It usually aliases
46	to the double type in C.	50	to the double type in C.
47		51
		52	=head1 GLOBAL FUNCTIONS
		53
		54	These functions can be called anytime, even before initialising the
		55	library in any way.
		56
48	=over 4	57	=over 4
49		58
50	=item ev_tstamp ev_time ()	59	=item ev_tstamp ev_time ()
51		60
52	Returns the current time as libev would use it.	61	Returns the current time as libev would use it. Please note that the
		62	C<ev_now> function is usually faster and also often returns the timestamp
		63	you actually want to know.
53		64
54	=item int ev_version_major ()	65	=item int ev_version_major ()
55		66
56	=item int ev_version_minor ()	67	=item int ev_version_minor ()
57		68
…		…
59	you linked against by calling the functions C<ev_version_major> and	70	you linked against by calling the functions C<ev_version_major> and
60	C<ev_version_minor>. If you want, you can compare against the global	71	C<ev_version_minor>. If you want, you can compare against the global
61	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	72	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
62	version of the library your program was compiled against.	73	version of the library your program was compiled against.
63		74
64	Usually, its a good idea to terminate if the major versions mismatch,	75	Usually, it's a good idea to terminate if the major versions mismatch,
65	as this indicates an incompatible change. Minor versions are usually	76	as this indicates an incompatible change. Minor versions are usually
66	compatible to older versions, so a larger minor version alone is usually	77	compatible to older versions, so a larger minor version alone is usually
67	not a problem.	78	not a problem.
68		79
		80	=item unsigned int ev_supported_backends ()
		81
		82	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
		83	value) compiled into this binary of libev (independent of their
		84	availability on the system you are running on). See C<ev_default_loop> for
		85	a description of the set values.
		86
		87	=item unsigned int ev_recommended_backends ()
		88
		89	Return the set of all backends compiled into this binary of libev and also
		90	recommended for this platform. This set is often smaller than the one
		91	returned by C<ev_supported_backends>, as for example kqueue is broken on
		92	most BSDs and will not be autodetected unless you explicitly request it
		93	(assuming you know what you are doing). This is the set of backends that
		94	libev will probe for if you specify no backends explicitly.
		95
69	=item ev_set_allocator (void (cb)(void *ptr, long size))	96	=item ev_set_allocator (void (cb)(void *ptr, long size))
70		97
71	Sets the allocation function to use (the prototype is similar to the	98	Sets the allocation function to use (the prototype is similar to the
72	realloc function). It is used to allocate and free memory (no surprises	99	realloc C function, the semantics are identical). It is used to allocate
73	here). If it returns zero when memory needs to be allocated, the library	100	and free memory (no surprises here). If it returns zero when memory
74	might abort or take some potentially destructive action. The default is	101	needs to be allocated, the library might abort or take some potentially
75	your system realloc function.	102	destructive action. The default is your system realloc function.
76		103
77	You could override this function in high-availability programs to, say,	104	You could override this function in high-availability programs to, say,
78	free some memory if it cannot allocate memory, to use a special allocator,	105	free some memory if it cannot allocate memory, to use a special allocator,
79	or even to sleep a while and retry until some memory is available.	106	or even to sleep a while and retry until some memory is available.
80		107
…		…
82		109
83	Set the callback function to call on a retryable syscall error (such	110	Set the callback function to call on a retryable syscall error (such
84	as failed select, poll, epoll_wait). The message is a printable string	111	as failed select, poll, epoll_wait). The message is a printable string
85	indicating the system call or subsystem causing the problem. If this	112	indicating the system call or subsystem causing the problem. If this
86	callback is set, then libev will expect it to remedy the sitution, no	113	callback is set, then libev will expect it to remedy the sitution, no
87	matter what, when it returns. That is, libev will geenrally retry the	114	matter what, when it returns. That is, libev will generally retry the
88	requested operation, or, if the condition doesn't go away, do bad stuff	115	requested operation, or, if the condition doesn't go away, do bad stuff
89	(such as abort).	116	(such as abort).
90		117
91	=back	118	=back
92		119
…		…
95	An event loop is described by a C<struct ev_loop *>. The library knows two	122	An event loop is described by a C<struct ev_loop *>. The library knows two
96	types of such loops, the I<default> loop, which supports signals and child	123	types of such loops, the I<default> loop, which supports signals and child
97	events, and dynamically created loops which do not.	124	events, and dynamically created loops which do not.
98		125
99	If you use threads, a common model is to run the default event loop	126	If you use threads, a common model is to run the default event loop
100	in your main thread (or in a separate thrad) and for each thread you	127	in your main thread (or in a separate thread) and for each thread you
101	create, you also create another event loop. Libev itself does no lockign	128	create, you also create another event loop. Libev itself does no locking
102	whatsoever, so if you mix calls to different event loops, make sure you	129	whatsoever, so if you mix calls to the same event loop in different
103	lock (this is usually a bad idea, though, even if done right).	130	threads, make sure you lock (this is usually a bad idea, though, even if
		131	done correctly, because it's hideous and inefficient).
104		132
105	=over 4	133	=over 4
106		134
107	=item struct ev_loop *ev_default_loop (unsigned int flags)	135	=item struct ev_loop *ev_default_loop (unsigned int flags)
108		136
109	This will initialise the default event loop if it hasn't been initialised	137	This will initialise the default event loop if it hasn't been initialised
110	yet and return it. If the default loop could not be initialised, returns	138	yet and return it. If the default loop could not be initialised, returns
111	false. If it already was initialised it simply returns it (and ignores the	139	false. If it already was initialised it simply returns it (and ignores the
112	flags).	140	flags. If that is troubling you, check C<ev_backend ()> afterwards).
113		141
114	If you don't know what event loop to use, use the one returned from this	142	If you don't know what event loop to use, use the one returned from this
115	function.	143	function.
116		144
117	The flags argument can be used to specify special behaviour or specific	145	The flags argument can be used to specify special behaviour or specific
118	backends to use, and is usually specified as 0 (or EVFLAG_AUTO)	146	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
119		147
120	It supports the following flags:	148	The following flags are supported:
121		149
122	=over 4	150	=over 4
123		151
124	=item EVFLAG_AUTO	152	=item C<EVFLAG_AUTO>
125		153
126	The default flags value. Use this if you have no clue (its the right	154	The default flags value. Use this if you have no clue (it's the right
127	thing, believe me).	155	thing, believe me).
128		156
129	=item EVFLAG_NOENV	157	=item C<EVFLAG_NOENV>
130		158
131	If this flag bit is ored into the flag value then libev will I<not> look	159	If this flag bit is ored into the flag value (or the program runs setuid
132	at the environment variable C<LIBEV_FLAGS>. Otherwise (the default), this	160	or setgid) then libev will I<not> look at the environment variable
133	environment variable will override the flags completely. This is useful	161	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
		162	override the flags completely if it is found in the environment. This is
134	to try out specific backends to tets their performance, or to work around	163	useful to try out specific backends to test their performance, or to work
135	bugs.	164	around bugs.
136		165
137	=item EVMETHOD_SELECT portable select backend	166	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
138		167
139	=item EVMETHOD_POLL poll backend (everywhere except windows)	168	This is your standard select(2) backend. Not I<completely> standard, as
		169	libev tries to roll its own fd_set with no limits on the number of fds,
		170	but if that fails, expect a fairly low limit on the number of fds when
		171	using this backend. It doesn't scale too well (O(highest_fd)), but its usually
		172	the fastest backend for a low number of fds.
140		173
141	=item EVMETHOD_EPOLL linux only	174	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
142		175
143	=item EVMETHOD_KQUEUE some bsds only	176	And this is your standard poll(2) backend. It's more complicated than
		177	select, but handles sparse fds better and has no artificial limit on the
		178	number of fds you can use (except it will slow down considerably with a
		179	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
144		180
145	=item EVMETHOD_DEVPOLL solaris 8 only	181	=item C<EVBACKEND_EPOLL> (value 4, Linux)
146		182
147	=item EVMETHOD_PORT solaris 10 only	183	For few fds, this backend is a bit little slower than poll and select,
		184	but it scales phenomenally better. While poll and select usually scale like
		185	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
		186	either O(1) or O(active_fds).
		187
		188	While stopping and starting an I/O watcher in the same iteration will
		189	result in some caching, there is still a syscall per such incident
		190	(because the fd could point to a different file description now), so its
		191	best to avoid that. Also, dup()ed file descriptors might not work very
		192	well if you register events for both fds.
		193
		194	Please note that epoll sometimes generates spurious notifications, so you
		195	need to use non-blocking I/O or other means to avoid blocking when no data
		196	(or space) is available.
		197
		198	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
		199
		200	Kqueue deserves special mention, as at the time of this writing, it
		201	was broken on all BSDs except NetBSD (usually it doesn't work with
		202	anything but sockets and pipes, except on Darwin, where of course its
		203	completely useless). For this reason its not being "autodetected"
		204	unless you explicitly specify it explicitly in the flags (i.e. using
		205	C<EVBACKEND_KQUEUE>).
		206
		207	It scales in the same way as the epoll backend, but the interface to the
		208	kernel is more efficient (which says nothing about its actual speed, of
		209	course). While starting and stopping an I/O watcher does not cause an
		210	extra syscall as with epoll, it still adds up to four event changes per
		211	incident, so its best to avoid that.
		212
		213	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
		214
		215	This is not implemented yet (and might never be).
		216
		217	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
		218
		219	This uses the Solaris 10 port mechanism. As with everything on Solaris,
		220	it's really slow, but it still scales very well (O(active_fds)).
		221
		222	Please note that solaris ports can result in a lot of spurious
		223	notifications, so you need to use non-blocking I/O or other means to avoid
		224	blocking when no data (or space) is available.
		225
		226	=item C<EVBACKEND_ALL>
		227
		228	Try all backends (even potentially broken ones that wouldn't be tried
		229	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
		230	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
		231
		232	=back
148		233
149	If one or more of these are ored into the flags value, then only these	234	If one or more of these are ored into the flags value, then only these
150	backends will be tried (in the reverse order as given here). If one are	235	backends will be tried (in the reverse order as given here). If none are
151	specified, any backend will do.	236	specified, most compiled-in backend will be tried, usually in reverse
		237	order of their flag values :)
152		238
153	=back	239	The most typical usage is like this:
		240
		241	if (!ev_default_loop (0))
		242	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		243
		244	Restrict libev to the select and poll backends, and do not allow
		245	environment settings to be taken into account:
		246
		247	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
		248
		249	Use whatever libev has to offer, but make sure that kqueue is used if
		250	available (warning, breaks stuff, best use only with your own private
		251	event loop and only if you know the OS supports your types of fds):
		252
		253	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
154		254
155	=item struct ev_loop *ev_loop_new (unsigned int flags)	255	=item struct ev_loop *ev_loop_new (unsigned int flags)
156		256
157	Similar to C<ev_default_loop>, but always creates a new event loop that is	257	Similar to C<ev_default_loop>, but always creates a new event loop that is
158	always distinct from the default loop. Unlike the default loop, it cannot	258	always distinct from the default loop. Unlike the default loop, it cannot
…		…
161		261
162	=item ev_default_destroy ()	262	=item ev_default_destroy ()
163		263
164	Destroys the default loop again (frees all memory and kernel state	264	Destroys the default loop again (frees all memory and kernel state
165	etc.). This stops all registered event watchers (by not touching them in	265	etc.). This stops all registered event watchers (by not touching them in
166	any way whatsoever, although you cnanot rely on this :).	266	any way whatsoever, although you cannot rely on this :).
167		267
168	=item ev_loop_destroy (loop)	268	=item ev_loop_destroy (loop)
169		269
170	Like C<ev_default_destroy>, but destroys an event loop created by an	270	Like C<ev_default_destroy>, but destroys an event loop created by an
171	earlier call to C<ev_loop_new>.	271	earlier call to C<ev_loop_new>.
…		…
175	This function reinitialises the kernel state for backends that have	275	This function reinitialises the kernel state for backends that have
176	one. Despite the name, you can call it anytime, but it makes most sense	276	one. Despite the name, you can call it anytime, but it makes most sense
177	after forking, in either the parent or child process (or both, but that	277	after forking, in either the parent or child process (or both, but that
178	again makes little sense).	278	again makes little sense).
179		279
180	You I<must> call this function after forking if and only if you want to	280	You I<must> call this function in the child process after forking if and
181	use the event library in both processes. If you just fork+exec, you don't	281	only if you want to use the event library in both processes. If you just
182	have to call it.	282	fork+exec, you don't have to call it.
183		283
184	The function itself is quite fast and its usually not a problem to call	284	The function itself is quite fast and it's usually not a problem to call
185	it just in case after a fork. To make this easy, the function will fit in	285	it just in case after a fork. To make this easy, the function will fit in
186	quite nicely into a call to C<pthread_atfork>:	286	quite nicely into a call to C<pthread_atfork>:
187		287
188	pthread_atfork (0, 0, ev_default_fork);	288	pthread_atfork (0, 0, ev_default_fork);
		289
		290	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
		291	without calling this function, so if you force one of those backends you
		292	do not need to care.
189		293
190	=item ev_loop_fork (loop)	294	=item ev_loop_fork (loop)
191		295
192	Like C<ev_default_fork>, but acts on an event loop created by	296	Like C<ev_default_fork>, but acts on an event loop created by
193	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	297	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
194	after fork, and how you do this is entirely your own problem.	298	after fork, and how you do this is entirely your own problem.
195		299
196	=item unsigned int ev_method (loop)	300	=item unsigned int ev_backend (loop)
197		301
198	Returns one of the C<EVMETHOD_*> flags indicating the event backend in	302	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
199	use.	303	use.
200		304
201	=item ev_tstamp = ev_now (loop)	305	=item ev_tstamp ev_now (loop)
202		306
203	Returns the current "event loop time", which is the time the event loop	307	Returns the current "event loop time", which is the time the event loop
204	got events and started processing them. This timestamp does not change	308	got events and started processing them. This timestamp does not change
205	as long as callbacks are being processed, and this is also the base time	309	as long as callbacks are being processed, and this is also the base time
206	used for relative timers. You can treat it as the timestamp of the event	310	used for relative timers. You can treat it as the timestamp of the event
…		…
210		314
211	Finally, this is it, the event handler. This function usually is called	315	Finally, this is it, the event handler. This function usually is called
212	after you initialised all your watchers and you want to start handling	316	after you initialised all your watchers and you want to start handling
213	events.	317	events.
214		318
215	If the flags argument is specified as 0, it will not return until either	319	If the flags argument is specified as C<0>, it will not return until
216	no event watchers are active anymore or C<ev_unloop> was called.	320	either no event watchers are active anymore or C<ev_unloop> was called.
217		321
218	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	322	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
219	those events and any outstanding ones, but will not block your process in	323	those events and any outstanding ones, but will not block your process in
220	case there are no events.	324	case there are no events and will return after one iteration of the loop.
221		325
222	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	326	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
223	neccessary) and will handle those and any outstanding ones. It will block	327	neccessary) and will handle those and any outstanding ones. It will block
224	your process until at least one new event arrives.	328	your process until at least one new event arrives, and will return after
		329	one iteration of the loop. This is useful if you are waiting for some
		330	external event in conjunction with something not expressible using other
		331	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
		332	usually a better approach for this kind of thing.
225		333
226	This flags value could be used to implement alternative looping	334	Here are the gory details of what C<ev_loop> does:
227	constructs, but the C<prepare> and C<check> watchers provide a better and	335
228	more generic mechanism.	336	* If there are no active watchers (reference count is zero), return.
		337	- Queue prepare watchers and then call all outstanding watchers.
		338	- If we have been forked, recreate the kernel state.
		339	- Update the kernel state with all outstanding changes.
		340	- Update the "event loop time".
		341	- Calculate for how long to block.
		342	- Block the process, waiting for any events.
		343	- Queue all outstanding I/O (fd) events.
		344	- Update the "event loop time" and do time jump handling.
		345	- Queue all outstanding timers.
		346	- Queue all outstanding periodics.
		347	- If no events are pending now, queue all idle watchers.
		348	- Queue all check watchers.
		349	- Call all queued watchers in reverse order (i.e. check watchers first).
		350	Signals and child watchers are implemented as I/O watchers, and will
		351	be handled here by queueing them when their watcher gets executed.
		352	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		353	were used, return, otherwise continue with step *.
229		354
230	=item ev_unloop (loop, how)	355	=item ev_unloop (loop, how)
231		356
232	Can be used to make a call to C<ev_loop> return early. The C<how> argument	357	Can be used to make a call to C<ev_loop> return early (but only after it
		358	has processed all outstanding events). The C<how> argument must be either
233	must be either C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop>	359	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
234	call return, or C<EVUNLOOP_ALL>, which will make all nested C<ev_loop>	360	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
235	calls return.
236		361
237	=item ev_ref (loop)	362	=item ev_ref (loop)
238		363
239	=item ev_unref (loop)	364	=item ev_unref (loop)
240		365
241	Ref/unref can be used to add or remove a refcount on the event loop: Every	366	Ref/unref can be used to add or remove a reference count on the event
242	watcher keeps one reference. If you have a long-runing watcher you never	367	loop: Every watcher keeps one reference, and as long as the reference
243	unregister that should not keep ev_loop from running, ev_unref() after	368	count is nonzero, C<ev_loop> will not return on its own. If you have
244	starting, and ev_ref() before stopping it. Libev itself uses this for	369	a watcher you never unregister that should not keep C<ev_loop> from
245	example for its internal signal pipe: It is not visible to you as a user	370	returning, ev_unref() after starting, and ev_ref() before stopping it. For
246	and should not keep C<ev_loop> from exiting if the work is done. It is	371	example, libev itself uses this for its internal signal pipe: It is not
247	also an excellent way to do this for generic recurring timers or from	372	visible to the libev user and should not keep C<ev_loop> from exiting if
248	within third-party libraries. Just remember to unref after start and ref	373	no event watchers registered by it are active. It is also an excellent
249	before stop.	374	way to do this for generic recurring timers or from within third-party
		375	libraries. Just remember to I<unref after start> and I<ref before stop>.
250		376
251	=back	377	=back
252		378
253	=head1 ANATOMY OF A WATCHER	379	=head1 ANATOMY OF A WATCHER
254		380
255	A watcher is a structure that you create and register to record your	381	A watcher is a structure that you create and register to record your
256	interest in some event. For instance, if you want to wait for STDIN to	382	interest in some event. For instance, if you want to wait for STDIN to
257	become readable, you would create an ev_io watcher for that:	383	become readable, you would create an C<ev_io> watcher for that:
258		384
259	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	385	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
260	{	386	{
261	ev_io_stop (w);	387	ev_io_stop (w);
262	ev_unloop (loop, EVUNLOOP_ALL);	388	ev_unloop (loop, EVUNLOOP_ALL);
…		…
289	*) >>), and you can stop watching for events at any time by calling the	415	*) >>), and you can stop watching for events at any time by calling the
290	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	416	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
291		417
292	As long as your watcher is active (has been started but not stopped) you	418	As long as your watcher is active (has been started but not stopped) you
293	must not touch the values stored in it. Most specifically you must never	419	must not touch the values stored in it. Most specifically you must never
294	reinitialise it or call its set method.	420	reinitialise it or call its set macro.
295		421
296	You cna check wether an event is active by calling the C<ev_is_active	422	You can check whether an event is active by calling the C<ev_is_active
297	(watcher *)> macro. To see wether an event is outstanding (but the	423	(watcher *)> macro. To see whether an event is outstanding (but the
298	callback for it has not been called yet) you cna use the C<ev_is_pending	424	callback for it has not been called yet) you can use the C<ev_is_pending
299	(watcher *)> macro.	425	(watcher *)> macro.
300		426
301	Each and every callback receives the event loop pointer as first, the	427	Each and every callback receives the event loop pointer as first, the
302	registered watcher structure as second, and a bitset of received events as	428	registered watcher structure as second, and a bitset of received events as
303	third argument.	429	third argument.
304		430
305	The rceeived events usually include a single bit per event type received	431	The received events usually include a single bit per event type received
306	(you can receive multiple events at the same time). The possible bit masks	432	(you can receive multiple events at the same time). The possible bit masks
307	are:	433	are:
308		434
309	=over 4	435	=over 4
310		436
311	=item EV_READ	437	=item C<EV_READ>
312		438
313	=item EV_WRITE	439	=item C<EV_WRITE>
314		440
315	The file descriptor in the ev_io watcher has become readable and/or	441	The file descriptor in the C<ev_io> watcher has become readable and/or
316	writable.	442	writable.
317		443
318	=item EV_TIMEOUT	444	=item C<EV_TIMEOUT>
319		445
320	The ev_timer watcher has timed out.	446	The C<ev_timer> watcher has timed out.
321		447
322	=item EV_PERIODIC	448	=item C<EV_PERIODIC>
323		449
324	The ev_periodic watcher has timed out.	450	The C<ev_periodic> watcher has timed out.
325		451
326	=item EV_SIGNAL	452	=item C<EV_SIGNAL>
327		453
328	The signal specified in the ev_signal watcher has been received by a thread.	454	The signal specified in the C<ev_signal> watcher has been received by a thread.
329		455
330	=item EV_CHILD	456	=item C<EV_CHILD>
331		457
332	The pid specified in the ev_child watcher has received a status change.	458	The pid specified in the C<ev_child> watcher has received a status change.
333		459
334	=item EV_IDLE	460	=item C<EV_IDLE>
335		461
336	The ev_idle watcher has determined that you have nothing better to do.	462	The C<ev_idle> watcher has determined that you have nothing better to do.
337		463
338	=item EV_PREPARE	464	=item C<EV_PREPARE>
339		465
340	=item EV_CHECK	466	=item C<EV_CHECK>
341		467
342	All ev_prepare watchers are invoked just I<before> C<ev_loop> starts	468	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts
343	to gather new events, and all ev_check watchers are invoked just after	469	to gather new events, and all C<ev_check> watchers are invoked just after
344	C<ev_loop> has gathered them, but before it invokes any callbacks for any	470	C<ev_loop> has gathered them, but before it invokes any callbacks for any
345	received events. Callbacks of both watcher types can start and stop as	471	received events. Callbacks of both watcher types can start and stop as
346	many watchers as they want, and all of them will be taken into account	472	many watchers as they want, and all of them will be taken into account
347	(for example, a ev_prepare watcher might start an idle watcher to keep	473	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
348	C<ev_loop> from blocking).	474	C<ev_loop> from blocking).
349		475
350	=item EV_ERROR	476	=item C<EV_ERROR>
351		477
352	An unspecified error has occured, the watcher has been stopped. This might	478	An unspecified error has occured, the watcher has been stopped. This might
353	happen because the watcher could not be properly started because libev	479	happen because the watcher could not be properly started because libev
354	ran out of memory, a file descriptor was found to be closed or any other	480	ran out of memory, a file descriptor was found to be closed or any other
355	problem. You best act on it by reporting the problem and somehow coping	481	problem. You best act on it by reporting the problem and somehow coping
…		…
364	=back	490	=back
365		491
366	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	492	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
367		493
368	Each watcher has, by default, a member C<void *data> that you can change	494	Each watcher has, by default, a member C<void *data> that you can change
369	and read at any time, libev will completely ignore it. This cna be used	495	and read at any time, libev will completely ignore it. This can be used
370	to associate arbitrary data with your watcher. If you need more data and	496	to associate arbitrary data with your watcher. If you need more data and
371	don't want to allocate memory and store a pointer to it in that data	497	don't want to allocate memory and store a pointer to it in that data
372	member, you can also "subclass" the watcher type and provide your own	498	member, you can also "subclass" the watcher type and provide your own
373	data:	499	data:
374		500
…		…
396	=head1 WATCHER TYPES	522	=head1 WATCHER TYPES
397		523
398	This section describes each watcher in detail, but will not repeat	524	This section describes each watcher in detail, but will not repeat
399	information given in the last section.	525	information given in the last section.
400		526
401	=head2 struct ev_io - is my file descriptor readable or writable	527	=head2 C<ev_io> - is this file descriptor readable or writable
402		528
403	I/O watchers check wether a file descriptor is readable or writable	529	I/O watchers check whether a file descriptor is readable or writable
404	in each iteration of the event loop (This behaviour is called	530	in each iteration of the event loop (This behaviour is called
405	level-triggering because you keep receiving events as long as the	531	level-triggering because you keep receiving events as long as the
406	condition persists. Remember you cna stop the watcher if you don't want to	532	condition persists. Remember you can stop the watcher if you don't want to
407	act on the event and neither want to receive future events).	533	act on the event and neither want to receive future events).
408		534
		535	In general you can register as many read and/or write event watchers per
		536	fd as you want (as long as you don't confuse yourself). Setting all file
		537	descriptors to non-blocking mode is also usually a good idea (but not
		538	required if you know what you are doing).
		539
		540	You have to be careful with dup'ed file descriptors, though. Some backends
		541	(the linux epoll backend is a notable example) cannot handle dup'ed file
		542	descriptors correctly if you register interest in two or more fds pointing
		543	to the same underlying file/socket etc. description (that is, they share
		544	the same underlying "file open").
		545
		546	If you must do this, then force the use of a known-to-be-good backend
		547	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
		548	C<EVBACKEND_POLL>).
		549
409	=over 4	550	=over 4
410		551
411	=item ev_io_init (ev_io *, callback, int fd, int events)	552	=item ev_io_init (ev_io *, callback, int fd, int events)
412		553
413	=item ev_io_set (ev_io *, int fd, int events)	554	=item ev_io_set (ev_io *, int fd, int events)
414		555
415	Configures an ev_io watcher. The fd is the file descriptor to rceeive	556	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive
416	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|	557	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|
417	EV_WRITE> to receive the given events.	558	EV_WRITE> to receive the given events.
418		559
419	=back	560	Please note that most of the more scalable backend mechanisms (for example
		561	epoll and solaris ports) can result in spurious readyness notifications
		562	for file descriptors, so you practically need to use non-blocking I/O (and
		563	treat callback invocation as hint only), or retest separately with a safe
		564	interface before doing I/O (XLib can do this), or force the use of either
		565	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this
		566	problem. Also note that it is quite easy to have your callback invoked
		567	when the readyness condition is no longer valid even when employing
		568	typical ways of handling events, so its a good idea to use non-blocking
		569	I/O unconditionally.
420		570
		571	=back
		572
421	=head2 struct ev_timer - relative and optionally recurring timeouts	573	=head2 C<ev_timer> - relative and optionally recurring timeouts
422		574
423	Timer watchers are simple relative timers that generate an event after a	575	Timer watchers are simple relative timers that generate an event after a
424	given time, and optionally repeating in regular intervals after that.	576	given time, and optionally repeating in regular intervals after that.
425		577
426	The timers are based on real time, that is, if you register an event that	578	The timers are based on real time, that is, if you register an event that
427	times out after an hour and youreset your system clock to last years	579	times out after an hour and you reset your system clock to last years
428	time, it will still time out after (roughly) and hour. "Roughly" because	580	time, it will still time out after (roughly) and hour. "Roughly" because
429	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	581	detecting time jumps is hard, and some inaccuracies are unavoidable (the
430	monotonic clock option helps a lot here).	582	monotonic clock option helps a lot here).
		583
		584	The relative timeouts are calculated relative to the C<ev_now ()>
		585	time. This is usually the right thing as this timestamp refers to the time
		586	of the event triggering whatever timeout you are modifying/starting. If
		587	you suspect event processing to be delayed and you I<need> to base the timeout
		588	on the current time, use something like this to adjust for this:
		589
		590	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
		591
		592	The callback is guarenteed to be invoked only when its timeout has passed,
		593	but if multiple timers become ready during the same loop iteration then
		594	order of execution is undefined.
431		595
432	=over 4	596	=over 4
433		597
434	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	598	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
435		599
…		…
441	later, again, and again, until stopped manually.	605	later, again, and again, until stopped manually.
442		606
443	The timer itself will do a best-effort at avoiding drift, that is, if you	607	The timer itself will do a best-effort at avoiding drift, that is, if you
444	configure a timer to trigger every 10 seconds, then it will trigger at	608	configure a timer to trigger every 10 seconds, then it will trigger at
445	exactly 10 second intervals. If, however, your program cannot keep up with	609	exactly 10 second intervals. If, however, your program cannot keep up with
446	the timer (ecause it takes longer than those 10 seconds to do stuff) the	610	the timer (because it takes longer than those 10 seconds to do stuff) the
447	timer will not fire more than once per event loop iteration.	611	timer will not fire more than once per event loop iteration.
448		612
449	=item ev_timer_again (loop)	613	=item ev_timer_again (loop)
450		614
451	This will act as if the timer timed out and restart it again if it is	615	This will act as if the timer timed out and restart it again if it is
…		…
458		622
459	This sounds a bit complicated, but here is a useful and typical	623	This sounds a bit complicated, but here is a useful and typical
460	example: Imagine you have a tcp connection and you want a so-called idle	624	example: Imagine you have a tcp connection and you want a so-called idle
461	timeout, that is, you want to be called when there have been, say, 60	625	timeout, that is, you want to be called when there have been, say, 60
462	seconds of inactivity on the socket. The easiest way to do this is to	626	seconds of inactivity on the socket. The easiest way to do this is to
463	configure an ev_timer with after=repeat=60 and calling ev_timer_again each	627	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each
464	time you successfully read or write some data. If you go into an idle	628	time you successfully read or write some data. If you go into an idle
465	state where you do not expect data to travel on the socket, you can stop	629	state where you do not expect data to travel on the socket, you can stop
466	the timer, and again will automatically restart it if need be.	630	the timer, and again will automatically restart it if need be.
467		631
468	=back	632	=back
469		633
470	=head2 ev_periodic	634	=head2 C<ev_periodic> - to cron or not to cron
471		635
472	Periodic watchers are also timers of a kind, but they are very versatile	636	Periodic watchers are also timers of a kind, but they are very versatile
473	(and unfortunately a bit complex).	637	(and unfortunately a bit complex).
474		638
475	Unlike ev_timer's, they are not based on real time (or relative time)	639	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
476	but on wallclock time (absolute time). You can tell a periodic watcher	640	but on wallclock time (absolute time). You can tell a periodic watcher
477	to trigger "at" some specific point in time. For example, if you tell a	641	to trigger "at" some specific point in time. For example, if you tell a
478	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	642	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()
479	+ 10.>) and then reset your system clock to the last year, then it will	643	+ 10.>) and then reset your system clock to the last year, then it will
480	take a year to trigger the event (unlike an ev_timer, which would trigger	644	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
481	roughly 10 seconds later and of course not if you reset your system time	645	roughly 10 seconds later and of course not if you reset your system time
482	again).	646	again).
483		647
484	They can also be used to implement vastly more complex timers, such as	648	They can also be used to implement vastly more complex timers, such as
485	triggering an event on eahc midnight, local time.	649	triggering an event on eahc midnight, local time.
486		650
		651	As with timers, the callback is guarenteed to be invoked only when the
		652	time (C<at>) has been passed, but if multiple periodic timers become ready
		653	during the same loop iteration then order of execution is undefined.
		654
487	=over 4	655	=over 4
488		656
489	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	657	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
490		658
491	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	659	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
492		660
493	Lots of arguments, lets sort it out... There are basically three modes of	661	Lots of arguments, lets sort it out... There are basically three modes of
494	operation, and we will explain them from simplest to complex:	662	operation, and we will explain them from simplest to complex:
495
496		663
497	=over 4	664	=over 4
498		665
499	=item * absolute timer (interval = reschedule_cb = 0)	666	=item * absolute timer (interval = reschedule_cb = 0)
500		667
…		…
514		681
515	ev_periodic_set (&periodic, 0., 3600., 0);	682	ev_periodic_set (&periodic, 0., 3600., 0);
516		683
517	This doesn't mean there will always be 3600 seconds in between triggers,	684	This doesn't mean there will always be 3600 seconds in between triggers,
518	but only that the the callback will be called when the system time shows a	685	but only that the the callback will be called when the system time shows a
519	full hour (UTC), or more correct, when the system time is evenly divisible	686	full hour (UTC), or more correctly, when the system time is evenly divisible
520	by 3600.	687	by 3600.
521		688
522	Another way to think about it (for the mathematically inclined) is that	689	Another way to think about it (for the mathematically inclined) is that
523	ev_periodic will try to run the callback in this mode at the next possible	690	C<ev_periodic> will try to run the callback in this mode at the next possible
524	time where C<time = at (mod interval)>, regardless of any time jumps.	691	time where C<time = at (mod interval)>, regardless of any time jumps.
525		692
526	=item * manual reschedule mode (reschedule_cb = callback)	693	=item * manual reschedule mode (reschedule_cb = callback)
527		694
528	In this mode the values for C<interval> and C<at> are both being	695	In this mode the values for C<interval> and C<at> are both being
529	ignored. Instead, each time the periodic watcher gets scheduled, the	696	ignored. Instead, each time the periodic watcher gets scheduled, the
530	reschedule callback will be called with the watcher as first, and the	697	reschedule callback will be called with the watcher as first, and the
531	current time as second argument.	698	current time as second argument.
532		699
533	NOTE: I<This callback MUST NOT stop or destroy the periodic or any other	700	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
534	periodic watcher, ever, or make any event loop modificstions>. If you need	701	ever, or make any event loop modifications>. If you need to stop it,
535	to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.	702	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
		703	starting a prepare watcher).
536		704
537	Its prototype is c<ev_tstamp (reschedule_cb)(struct ev_periodic w,	705	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
538	ev_tstamp now)>, e.g.:	706	ev_tstamp now)>, e.g.:
539		707
540	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	708	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
541	{	709	{
542	return now + 60.;	710	return now + 60.;
…		…
545	It must return the next time to trigger, based on the passed time value	713	It must return the next time to trigger, based on the passed time value
546	(that is, the lowest time value larger than to the second argument). It	714	(that is, the lowest time value larger than to the second argument). It
547	will usually be called just before the callback will be triggered, but	715	will usually be called just before the callback will be triggered, but
548	might be called at other times, too.	716	might be called at other times, too.
549		717
		718	NOTE: I<< This callback must always return a time that is later than the
		719	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.
		720
550	This can be used to create very complex timers, such as a timer that	721	This can be used to create very complex timers, such as a timer that
551	triggers on each midnight, local time. To do this, you would calculate the	722	triggers on each midnight, local time. To do this, you would calculate the
552	next midnight after C<now> and return the timestamp value for this. How you do this	723	next midnight after C<now> and return the timestamp value for this. How
553	is, again, up to you (but it is not trivial).	724	you do this is, again, up to you (but it is not trivial, which is the main
		725	reason I omitted it as an example).
554		726
555	=back	727	=back
556		728
557	=item ev_periodic_again (loop, ev_periodic *)	729	=item ev_periodic_again (loop, ev_periodic *)
558		730
…		…
561	a different time than the last time it was called (e.g. in a crond like	733	a different time than the last time it was called (e.g. in a crond like
562	program when the crontabs have changed).	734	program when the crontabs have changed).
563		735
564	=back	736	=back
565		737
566	=head2 ev_signal - signal me when a signal gets signalled	738	=head2 C<ev_signal> - signal me when a signal gets signalled
567		739
568	Signal watchers will trigger an event when the process receives a specific	740	Signal watchers will trigger an event when the process receives a specific
569	signal one or more times. Even though signals are very asynchronous, libev	741	signal one or more times. Even though signals are very asynchronous, libev
570	will try its best to deliver signals synchronously, i.e. as part of the	742	will try it's best to deliver signals synchronously, i.e. as part of the
571	normal event processing, like any other event.	743	normal event processing, like any other event.
572		744
573	You cna configure as many watchers as you like per signal. Only when the	745	You can configure as many watchers as you like per signal. Only when the
574	first watcher gets started will libev actually register a signal watcher	746	first watcher gets started will libev actually register a signal watcher
575	with the kernel (thus it coexists with your own signal handlers as long	747	with the kernel (thus it coexists with your own signal handlers as long
576	as you don't register any with libev). Similarly, when the last signal	748	as you don't register any with libev). Similarly, when the last signal
577	watcher for a signal is stopped libev will reset the signal handler to	749	watcher for a signal is stopped libev will reset the signal handler to
578	SIG_DFL (regardless of what it was set to before).	750	SIG_DFL (regardless of what it was set to before).
…		…
586	Configures the watcher to trigger on the given signal number (usually one	758	Configures the watcher to trigger on the given signal number (usually one
587	of the C<SIGxxx> constants).	759	of the C<SIGxxx> constants).
588		760
589	=back	761	=back
590		762
591	=head2 ev_child - wait for pid status changes	763	=head2 C<ev_child> - wait for pid status changes
592		764
593	Child watchers trigger when your process receives a SIGCHLD in response to	765	Child watchers trigger when your process receives a SIGCHLD in response to
594	some child status changes (most typically when a child of yours dies).	766	some child status changes (most typically when a child of yours dies).
595		767
596	=over 4	768	=over 4
…		…
600	=item ev_child_set (ev_child *, int pid)	772	=item ev_child_set (ev_child *, int pid)
601		773
602	Configures the watcher to wait for status changes of process C<pid> (or	774	Configures the watcher to wait for status changes of process C<pid> (or
603	I<any> process if C<pid> is specified as C<0>). The callback can look	775	I<any> process if C<pid> is specified as C<0>). The callback can look
604	at the C<rstatus> member of the C<ev_child> watcher structure to see	776	at the C<rstatus> member of the C<ev_child> watcher structure to see
605	the status word (use the macros from C<sys/wait.h>). The C<rpid> member	777	the status word (use the macros from C<sys/wait.h> and see your systems
606	contains the pid of the process causing the status change.	778	C<waitpid> documentation). The C<rpid> member contains the pid of the
		779	process causing the status change.
607		780
608	=back	781	=back
609		782
610	=head2 ev_idle - when you've got nothing better to do	783	=head2 C<ev_idle> - when you've got nothing better to do
611		784
612	Idle watchers trigger events when there are no other I/O or timer (or	785	Idle watchers trigger events when there are no other events are pending
613	periodic) events pending. That is, as long as your process is busy	786	(prepare, check and other idle watchers do not count). That is, as long
614	handling sockets or timeouts it will not be called. But when your process	787	as your process is busy handling sockets or timeouts (or even signals,
615	is idle all idle watchers are being called again and again - until	788	imagine) it will not be triggered. But when your process is idle all idle
		789	watchers are being called again and again, once per event loop iteration -
616	stopped, that is, or your process receives more events.	790	until stopped, that is, or your process receives more events and becomes
		791	busy.
617		792
618	The most noteworthy effect is that as long as any idle watchers are	793	The most noteworthy effect is that as long as any idle watchers are
619	active, the process will not block when waiting for new events.	794	active, the process will not block when waiting for new events.
620		795
621	Apart from keeping your process non-blocking (which is a useful	796	Apart from keeping your process non-blocking (which is a useful
…		…
631	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	806	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
632	believe me.	807	believe me.
633		808
634	=back	809	=back
635		810
636	=head2 prepare and check - your hooks into the event loop	811	=head2 C<ev_prepare> and C<ev_check> - customise your event loop
637		812
638	Prepare and check watchers usually (but not always) are used in	813	Prepare and check watchers are usually (but not always) used in tandem:
639	tandom. Prepare watchers get invoked before the process blocks and check	814	prepare watchers get invoked before the process blocks and check watchers
640	watchers afterwards.	815	afterwards.
641		816
642	Their main purpose is to integrate other event mechanisms into libev. This	817	Their main purpose is to integrate other event mechanisms into libev. This
643	could be used, for example, to track variable changes, implement your own	818	could be used, for example, to track variable changes, implement your own
644	watchers, integrate net-snmp or a coroutine library and lots more.	819	watchers, integrate net-snmp or a coroutine library and lots more.
645		820
646	This is done by examining in each prepare call which file descriptors need	821	This is done by examining in each prepare call which file descriptors need
647	to be watched by the other library, registering ev_io watchers for them	822	to be watched by the other library, registering C<ev_io> watchers for
648	and starting an ev_timer watcher for any timeouts (many libraries provide	823	them and starting an C<ev_timer> watcher for any timeouts (many libraries
649	just this functionality). Then, in the check watcher you check for any	824	provide just this functionality). Then, in the check watcher you check for
650	events that occured (by making your callbacks set soem flags for example)	825	any events that occured (by checking the pending status of all watchers
651	and call back into the library.	826	and stopping them) and call back into the library. The I/O and timer
		827	callbacks will never actually be called (but must be valid nevertheless,
		828	because you never know, you know?).
652		829
653	As another example, the perl Coro module uses these hooks to integrate	830	As another example, the Perl Coro module uses these hooks to integrate
654	coroutines into libev programs, by yielding to other active coroutines	831	coroutines into libev programs, by yielding to other active coroutines
655	during each prepare and only letting the process block if no coroutines	832	during each prepare and only letting the process block if no coroutines
656	are ready to run.	833	are ready to run (it's actually more complicated: it only runs coroutines
		834	with priority higher than or equal to the event loop and one coroutine
		835	of lower priority, but only once, using idle watchers to keep the event
		836	loop from blocking if lower-priority coroutines are active, thus mapping
		837	low-priority coroutines to idle/background tasks).
657		838
658	=over 4	839	=over 4
659		840
660	=item ev_prepare_init (ev_prepare *, callback)	841	=item ev_prepare_init (ev_prepare *, callback)
661		842
662	=item ev_check_init (ev_check *, callback)	843	=item ev_check_init (ev_check *, callback)
663		844
664	Initialises and configures the prepare or check watcher - they have no	845	Initialises and configures the prepare or check watcher - they have no
665	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	846	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
666	macros, but using them is utterly, utterly pointless.	847	macros, but using them is utterly, utterly and completely pointless.
667		848
668	=back	849	=back
669		850
670	=head1 OTHER FUNCTIONS	851	=head1 OTHER FUNCTIONS
671		852
672	There are some other fucntions of possible interest. Described. Here. Now.	853	There are some other functions of possible interest. Described. Here. Now.
673		854
674	=over 4	855	=over 4
675		856
676	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	857	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
677		858
678	This function combines a simple timer and an I/O watcher, calls your	859	This function combines a simple timer and an I/O watcher, calls your
679	callback on whichever event happens first and automatically stop both	860	callback on whichever event happens first and automatically stop both
680	watchers. This is useful if you want to wait for a single event on an fd	861	watchers. This is useful if you want to wait for a single event on an fd
681	or timeout without havign to allocate/configure/start/stop/free one or	862	or timeout without having to allocate/configure/start/stop/free one or
682	more watchers yourself.	863	more watchers yourself.
683		864
684	If C<fd> is less than 0, then no I/O watcher will be started and events is	865	If C<fd> is less than 0, then no I/O watcher will be started and events
685	ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set	866	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
686	will be craeted and started.	867	C<events> set will be craeted and started.
687		868
688	If C<timeout> is less than 0, then no timeout watcher will be	869	If C<timeout> is less than 0, then no timeout watcher will be
689	started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat	870	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
690	= 0) will be started.	871	repeat = 0) will be started. While C<0> is a valid timeout, it is of
		872	dubious value.
691		873
692	The callback has the type C<void (cb)(int revents, void arg)> and	874	The callback has the type C<void (cb)(int revents, void arg)> and gets
693	gets passed an events set (normally a combination of EV_ERROR, EV_READ,	875	passed an C<revents> set like normal event callbacks (a combination of
694	EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>:	876	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
		877	value passed to C<ev_once>:
695		878
696	static void stdin_ready (int revents, void *arg)	879	static void stdin_ready (int revents, void *arg)
697	{	880	{
698	if (revents & EV_TIMEOUT)	881	if (revents & EV_TIMEOUT)
699	/* doh, nothing entered */	882	/* doh, nothing entered */;
700	else if (revents & EV_READ)	883	else if (revents & EV_READ)
701	/* stdin might have data for us, joy! */	884	/* stdin might have data for us, joy! */;
702	}	885	}
703		886
704	ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0);	887	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
705		888
706	=item ev_feed_event (loop, watcher, int events)	889	=item ev_feed_event (loop, watcher, int events)
707		890
708	Feeds the given event set into the event loop, as if the specified event	891	Feeds the given event set into the event loop, as if the specified event
709	has happened for the specified watcher (which must be a pointer to an	892	had happened for the specified watcher (which must be a pointer to an
710	initialised but not necessarily active event watcher).	893	initialised but not necessarily started event watcher).
711		894
712	=item ev_feed_fd_event (loop, int fd, int revents)	895	=item ev_feed_fd_event (loop, int fd, int revents)
713		896
714	Feed an event on the given fd, as if a file descriptor backend detected it.	897	Feed an event on the given fd, as if a file descriptor backend detected
		898	the given events it.
715		899
716	=item ev_feed_signal_event (loop, int signum)	900	=item ev_feed_signal_event (loop, int signum)
717		901
718	Feed an event as if the given signal occured (loop must be the default loop!).	902	Feed an event as if the given signal occured (loop must be the default loop!).
719		903
720	=back	904	=back
721		905
		906	=head1 LIBEVENT EMULATION
		907
		908	Libev offers a compatibility emulation layer for libevent. It cannot
		909	emulate the internals of libevent, so here are some usage hints:
		910
		911	=over 4
		912
		913	=item * Use it by including <event.h>, as usual.
		914
		915	=item * The following members are fully supported: ev_base, ev_callback,
		916	ev_arg, ev_fd, ev_res, ev_events.
		917
		918	=item * Avoid using ev_flags and the EVLIST_*-macros, while it is
		919	maintained by libev, it does not work exactly the same way as in libevent (consider
		920	it a private API).
		921
		922	=item * Priorities are not currently supported. Initialising priorities
		923	will fail and all watchers will have the same priority, even though there
		924	is an ev_pri field.
		925
		926	=item * Other members are not supported.
		927
		928	=item * The libev emulation is I<not> ABI compatible to libevent, you need
		929	to use the libev header file and library.
		930
		931	=back
		932
		933	=head1 C++ SUPPORT
		934
		935	TBD.
		936
722	=head1 AUTHOR	937	=head1 AUTHOR
723		938
724	Marc Lehmann <libev@schmorp.de>.	939	Marc Lehmann <libev@schmorp.de>.
725		940

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Revision 1.33 by root, Fri Nov 23 15:26:08 2007 UTC