[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 1.32 by root, Fri Nov 23 08:36:35 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	C<EVFLAG_AUTO> will probe for.
		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 EVFLAG_AUTO).
119		147
120	It supports the following flags:	148	It supports the following flags:
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" unless
		204	you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).
		205
		206	It scales in the same way as the epoll backend, but the interface to the
		207	kernel is more efficient (which says nothing about its actual speed, of
		208	course). While starting and stopping an I/O watcher does not cause an
		209	extra syscall as with epoll, it still adds up to four event changes per
		210	incident, so its best to avoid that.
		211
		212	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
		213
		214	This is not implemented yet (and might never be).
		215
		216	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
		217
		218	This uses the Solaris 10 port mechanism. As with everything on Solaris,
		219	it's really slow, but it still scales very well (O(active_fds)).
		220
		221	Please note that solaris ports can result in a lot of spurious
		222	notifications, so you need to use non-blocking I/O or other means to avoid
		223	blocking when no data (or space) is available.
		224
		225	=item C<EVBACKEND_ALL>
		226
		227	Try all backends (even potentially broken ones that wouldn't be tried
		228	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
		229	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
		230
		231	=back
148		232
149	If one or more of these are ored into the flags value, then only these	233	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	234	backends will be tried (in the reverse order as given here). If none are
151	specified, any backend will do.	235	specified, most compiled-in backend will be tried, usually in reverse
152		236	order of their flag values :)
153	=back
154		237
155	=item struct ev_loop *ev_loop_new (unsigned int flags)	238	=item struct ev_loop *ev_loop_new (unsigned int flags)
156		239
157	Similar to C<ev_default_loop>, but always creates a new event loop that is	240	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	241	always distinct from the default loop. Unlike the default loop, it cannot
…		…
161		244
162	=item ev_default_destroy ()	245	=item ev_default_destroy ()
163		246
164	Destroys the default loop again (frees all memory and kernel state	247	Destroys the default loop again (frees all memory and kernel state
165	etc.). This stops all registered event watchers (by not touching them in	248	etc.). This stops all registered event watchers (by not touching them in
166	any way whatsoever, although you cnanot rely on this :).	249	any way whatsoever, although you cannot rely on this :).
167		250
168	=item ev_loop_destroy (loop)	251	=item ev_loop_destroy (loop)
169		252
170	Like C<ev_default_destroy>, but destroys an event loop created by an	253	Like C<ev_default_destroy>, but destroys an event loop created by an
171	earlier call to C<ev_loop_new>.	254	earlier call to C<ev_loop_new>.
…		…
175	This function reinitialises the kernel state for backends that have	258	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	259	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	260	after forking, in either the parent or child process (or both, but that
178	again makes little sense).	261	again makes little sense).
179		262
180	You I<must> call this function after forking if and only if you want to	263	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	264	only if you want to use the event library in both processes. If you just
182	have to call it.	265	fork+exec, you don't have to call it.
183		266
184	The function itself is quite fast and its usually not a problem to call	267	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	268	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>:	269	quite nicely into a call to C<pthread_atfork>:
187		270
188	pthread_atfork (0, 0, ev_default_fork);	271	pthread_atfork (0, 0, ev_default_fork);
		272
		273	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
		274	without calling this function, so if you force one of those backends you
		275	do not need to care.
189		276
190	=item ev_loop_fork (loop)	277	=item ev_loop_fork (loop)
191		278
192	Like C<ev_default_fork>, but acts on an event loop created by	279	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	280	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.	281	after fork, and how you do this is entirely your own problem.
195		282
196	=item unsigned int ev_method (loop)	283	=item unsigned int ev_backend (loop)
197		284
198	Returns one of the C<EVMETHOD_*> flags indicating the event backend in	285	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
199	use.	286	use.
200		287
201	=item ev_tstamp = ev_now (loop)	288	=item ev_tstamp ev_now (loop)
202		289
203	Returns the current "event loop time", which is the time the event loop	290	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	291	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	292	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	293	used for relative timers. You can treat it as the timestamp of the event
…		…
215	If the flags argument is specified as 0, it will not return until either	302	If the flags argument is specified as 0, it will not return until either
216	no event watchers are active anymore or C<ev_unloop> was called.	303	no event watchers are active anymore or C<ev_unloop> was called.
217		304
218	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	305	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	306	those events and any outstanding ones, but will not block your process in
220	case there are no events.	307	case there are no events and will return after one iteration of the loop.
221		308
222	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	309	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	310	neccessary) and will handle those and any outstanding ones. It will block
224	your process until at least one new event arrives.	311	your process until at least one new event arrives, and will return after
		312	one iteration of the loop.
225		313
226	This flags value could be used to implement alternative looping	314	This flags value could be used to implement alternative looping
227	constructs, but the C<prepare> and C<check> watchers provide a better and	315	constructs, but the C<prepare> and C<check> watchers provide a better and
228	more generic mechanism.	316	more generic mechanism.
229		317
		318	Here are the gory details of what ev_loop does:
		319
		320	1. If there are no active watchers (reference count is zero), return.
		321	2. Queue and immediately call all prepare watchers.
		322	3. If we have been forked, recreate the kernel state.
		323	4. Update the kernel state with all outstanding changes.
		324	5. Update the "event loop time".
		325	6. Calculate for how long to block.
		326	7. Block the process, waiting for events.
		327	8. Update the "event loop time" and do time jump handling.
		328	9. Queue all outstanding timers.
		329	10. Queue all outstanding periodics.
		330	11. If no events are pending now, queue all idle watchers.
		331	12. Queue all check watchers.
		332	13. Call all queued watchers in reverse order (i.e. check watchers first).
		333	14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		334	was used, return, otherwise continue with step #1.
		335
230	=item ev_unloop (loop, how)	336	=item ev_unloop (loop, how)
231		337
232	Can be used to make a call to C<ev_loop> return early. The C<how> argument	338	Can be used to make a call to C<ev_loop> return early (but only after it
		339	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>	340	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>	341	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
235	calls return.
236		342
237	=item ev_ref (loop)	343	=item ev_ref (loop)
238		344
239	=item ev_unref (loop)	345	=item ev_unref (loop)
240		346
241	Ref/unref can be used to add or remove a refcount on the event loop: Every	347	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	348	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	349	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	350	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	351	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	352	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	353	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	354	no event watchers registered by it are active. It is also an excellent
249	before stop.	355	way to do this for generic recurring timers or from within third-party
		356	libraries. Just remember to I<unref after start> and I<ref before stop>.
250		357
251	=back	358	=back
252		359
253	=head1 ANATOMY OF A WATCHER	360	=head1 ANATOMY OF A WATCHER
254		361
255	A watcher is a structure that you create and register to record your	362	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	363	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:	364	become readable, you would create an C<ev_io> watcher for that:
258		365
259	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	366	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
260	{	367	{
261	ev_io_stop (w);	368	ev_io_stop (w);
262	ev_unloop (loop, EVUNLOOP_ALL);	369	ev_unloop (loop, EVUNLOOP_ALL);
…		…
289	*) >>), and you can stop watching for events at any time by calling the	396	*) >>), and you can stop watching for events at any time by calling the
290	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	397	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
291		398
292	As long as your watcher is active (has been started but not stopped) you	399	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	400	must not touch the values stored in it. Most specifically you must never
294	reinitialise it or call its set method.	401	reinitialise it or call its set macro.
295		402
296	You cna check wether an event is active by calling the C<ev_is_active	403	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	404	(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	405	callback for it has not been called yet) you can use the C<ev_is_pending
299	(watcher *)> macro.	406	(watcher *)> macro.
300		407
301	Each and every callback receives the event loop pointer as first, the	408	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	409	registered watcher structure as second, and a bitset of received events as
303	third argument.	410	third argument.
304		411
305	The rceeived events usually include a single bit per event type received	412	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	413	(you can receive multiple events at the same time). The possible bit masks
307	are:	414	are:
308		415
309	=over 4	416	=over 4
310		417
311	=item EV_READ	418	=item C<EV_READ>
312		419
313	=item EV_WRITE	420	=item C<EV_WRITE>
314		421
315	The file descriptor in the ev_io watcher has become readable and/or	422	The file descriptor in the C<ev_io> watcher has become readable and/or
316	writable.	423	writable.
317		424
318	=item EV_TIMEOUT	425	=item C<EV_TIMEOUT>
319		426
320	The ev_timer watcher has timed out.	427	The C<ev_timer> watcher has timed out.
321		428
322	=item EV_PERIODIC	429	=item C<EV_PERIODIC>
323		430
324	The ev_periodic watcher has timed out.	431	The C<ev_periodic> watcher has timed out.
325		432
326	=item EV_SIGNAL	433	=item C<EV_SIGNAL>
327		434
328	The signal specified in the ev_signal watcher has been received by a thread.	435	The signal specified in the C<ev_signal> watcher has been received by a thread.
329		436
330	=item EV_CHILD	437	=item C<EV_CHILD>
331		438
332	The pid specified in the ev_child watcher has received a status change.	439	The pid specified in the C<ev_child> watcher has received a status change.
333		440
334	=item EV_IDLE	441	=item C<EV_IDLE>
335		442
336	The ev_idle watcher has determined that you have nothing better to do.	443	The C<ev_idle> watcher has determined that you have nothing better to do.
337		444
338	=item EV_PREPARE	445	=item C<EV_PREPARE>
339		446
340	=item EV_CHECK	447	=item C<EV_CHECK>
341		448
342	All ev_prepare watchers are invoked just I<before> C<ev_loop> starts	449	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	450	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	451	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	452	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	453	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	454	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
348	C<ev_loop> from blocking).	455	C<ev_loop> from blocking).
349		456
350	=item EV_ERROR	457	=item C<EV_ERROR>
351		458
352	An unspecified error has occured, the watcher has been stopped. This might	459	An unspecified error has occured, the watcher has been stopped. This might
353	happen because the watcher could not be properly started because libev	460	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	461	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	462	problem. You best act on it by reporting the problem and somehow coping
…		…
364	=back	471	=back
365		472
366	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	473	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
367		474
368	Each watcher has, by default, a member C<void *data> that you can change	475	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	476	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	477	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	478	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	479	member, you can also "subclass" the watcher type and provide your own
373	data:	480	data:
374		481
…		…
396	=head1 WATCHER TYPES	503	=head1 WATCHER TYPES
397		504
398	This section describes each watcher in detail, but will not repeat	505	This section describes each watcher in detail, but will not repeat
399	information given in the last section.	506	information given in the last section.
400		507
401	=head2 struct ev_io - is my file descriptor readable or writable	508	=head2 C<ev_io> - is this file descriptor readable or writable
402		509
403	I/O watchers check wether a file descriptor is readable or writable	510	I/O watchers check whether a file descriptor is readable or writable
404	in each iteration of the event loop (This behaviour is called	511	in each iteration of the event loop (This behaviour is called
405	level-triggering because you keep receiving events as long as the	512	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	513	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).	514	act on the event and neither want to receive future events).
408		515
		516	In general you can register as many read and/or write event watchers per
		517	fd as you want (as long as you don't confuse yourself). Setting all file
		518	descriptors to non-blocking mode is also usually a good idea (but not
		519	required if you know what you are doing).
		520
		521	You have to be careful with dup'ed file descriptors, though. Some backends
		522	(the linux epoll backend is a notable example) cannot handle dup'ed file
		523	descriptors correctly if you register interest in two or more fds pointing
		524	to the same underlying file/socket etc. description (that is, they share
		525	the same underlying "file open").
		526
		527	If you must do this, then force the use of a known-to-be-good backend
		528	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
		529	C<EVBACKEND_POLL>).
		530
409	=over 4	531	=over 4
410		532
411	=item ev_io_init (ev_io *, callback, int fd, int events)	533	=item ev_io_init (ev_io *, callback, int fd, int events)
412		534
413	=item ev_io_set (ev_io *, int fd, int events)	535	=item ev_io_set (ev_io *, int fd, int events)
414		536
415	Configures an ev_io watcher. The fd is the file descriptor to rceeive	537	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 \|	538	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|
417	EV_WRITE> to receive the given events.	539	EV_WRITE> to receive the given events.
418		540
419	=back	541	Please note that most of the more scalable backend mechanisms (for example
		542	epoll and solaris ports) can result in spurious readyness notifications
		543	for file descriptors, so you practically need to use non-blocking I/O (and
		544	treat callback invocation as hint only), or retest separately with a safe
		545	interface before doing I/O (XLib can do this), or force the use of either
		546	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this
		547	problem. Also note that it is quite easy to have your callback invoked
		548	when the readyness condition is no longer valid even when employing
		549	typical ways of handling events, so its a good idea to use non-blocking
		550	I/O unconditionally.
420		551
		552	=back
		553
421	=head2 struct ev_timer - relative and optionally recurring timeouts	554	=head2 C<ev_timer> - relative and optionally recurring timeouts
422		555
423	Timer watchers are simple relative timers that generate an event after a	556	Timer watchers are simple relative timers that generate an event after a
424	given time, and optionally repeating in regular intervals after that.	557	given time, and optionally repeating in regular intervals after that.
425		558
426	The timers are based on real time, that is, if you register an event that	559	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	560	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	561	time, it will still time out after (roughly) and hour. "Roughly" because
429	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	562	detecting time jumps is hard, and some inaccuracies are unavoidable (the
430	monotonic clock option helps a lot here).	563	monotonic clock option helps a lot here).
		564
		565	The relative timeouts are calculated relative to the C<ev_now ()>
		566	time. This is usually the right thing as this timestamp refers to the time
		567	of the event triggering whatever timeout you are modifying/starting. If
		568	you suspect event processing to be delayed and you I<need> to base the timeout
		569	on the current time, use something like this to adjust for this:
		570
		571	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
		572
		573	The callback is guarenteed to be invoked only when its timeout has passed,
		574	but if multiple timers become ready during the same loop iteration then
		575	order of execution is undefined.
431		576
432	=over 4	577	=over 4
433		578
434	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	579	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
435		580
…		…
441	later, again, and again, until stopped manually.	586	later, again, and again, until stopped manually.
442		587
443	The timer itself will do a best-effort at avoiding drift, that is, if you	588	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	589	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	590	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	591	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.	592	timer will not fire more than once per event loop iteration.
448		593
449	=item ev_timer_again (loop)	594	=item ev_timer_again (loop)
450		595
451	This will act as if the timer timed out and restart it again if it is	596	This will act as if the timer timed out and restart it again if it is
…		…
458		603
459	This sounds a bit complicated, but here is a useful and typical	604	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	605	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	606	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	607	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	608	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	609	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	610	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.	611	the timer, and again will automatically restart it if need be.
467		612
468	=back	613	=back
469		614
470	=head2 ev_periodic	615	=head2 C<ev_periodic> - to cron or not to cron
471		616
472	Periodic watchers are also timers of a kind, but they are very versatile	617	Periodic watchers are also timers of a kind, but they are very versatile
473	(and unfortunately a bit complex).	618	(and unfortunately a bit complex).
474		619
475	Unlike ev_timer's, they are not based on real time (or relative time)	620	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	621	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	622	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 ()	623	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	624	+ 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	625	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	626	roughly 10 seconds later and of course not if you reset your system time
482	again).	627	again).
483		628
484	They can also be used to implement vastly more complex timers, such as	629	They can also be used to implement vastly more complex timers, such as
485	triggering an event on eahc midnight, local time.	630	triggering an event on eahc midnight, local time.
486		631
		632	As with timers, the callback is guarenteed to be invoked only when the
		633	time (C<at>) has been passed, but if multiple periodic timers become ready
		634	during the same loop iteration then order of execution is undefined.
		635
487	=over 4	636	=over 4
488		637
489	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	638	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
490		639
491	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	640	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
492		641
493	Lots of arguments, lets sort it out... There are basically three modes of	642	Lots of arguments, lets sort it out... There are basically three modes of
494	operation, and we will explain them from simplest to complex:	643	operation, and we will explain them from simplest to complex:
495
496		644
497	=over 4	645	=over 4
498		646
499	=item * absolute timer (interval = reschedule_cb = 0)	647	=item * absolute timer (interval = reschedule_cb = 0)
500		648
…		…
514		662
515	ev_periodic_set (&periodic, 0., 3600., 0);	663	ev_periodic_set (&periodic, 0., 3600., 0);
516		664
517	This doesn't mean there will always be 3600 seconds in between triggers,	665	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	666	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	667	full hour (UTC), or more correctly, when the system time is evenly divisible
520	by 3600.	668	by 3600.
521		669
522	Another way to think about it (for the mathematically inclined) is that	670	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	671	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.	672	time where C<time = at (mod interval)>, regardless of any time jumps.
525		673
526	=item * manual reschedule mode (reschedule_cb = callback)	674	=item * manual reschedule mode (reschedule_cb = callback)
527		675
528	In this mode the values for C<interval> and C<at> are both being	676	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	677	ignored. Instead, each time the periodic watcher gets scheduled, the
530	reschedule callback will be called with the watcher as first, and the	678	reschedule callback will be called with the watcher as first, and the
531	current time as second argument.	679	current time as second argument.
532		680
533	NOTE: I<This callback MUST NOT stop or destroy the periodic or any other	681	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	682	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.	683	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
		684	starting a prepare watcher).
536		685
537	Its prototype is c<ev_tstamp (reschedule_cb)(struct ev_periodic w,	686	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
538	ev_tstamp now)>, e.g.:	687	ev_tstamp now)>, e.g.:
539		688
540	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	689	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
541	{	690	{
542	return now + 60.;	691	return now + 60.;
…		…
545	It must return the next time to trigger, based on the passed time value	694	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	695	(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	696	will usually be called just before the callback will be triggered, but
548	might be called at other times, too.	697	might be called at other times, too.
549		698
		699	NOTE: I<< This callback must always return a time that is later than the
		700	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.
		701
550	This can be used to create very complex timers, such as a timer that	702	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	703	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	704	next midnight after C<now> and return the timestamp value for this. How
553	is, again, up to you (but it is not trivial).	705	you do this is, again, up to you (but it is not trivial, which is the main
		706	reason I omitted it as an example).
554		707
555	=back	708	=back
556		709
557	=item ev_periodic_again (loop, ev_periodic *)	710	=item ev_periodic_again (loop, ev_periodic *)
558		711
…		…
561	a different time than the last time it was called (e.g. in a crond like	714	a different time than the last time it was called (e.g. in a crond like
562	program when the crontabs have changed).	715	program when the crontabs have changed).
563		716
564	=back	717	=back
565		718
566	=head2 ev_signal - signal me when a signal gets signalled	719	=head2 C<ev_signal> - signal me when a signal gets signalled
567		720
568	Signal watchers will trigger an event when the process receives a specific	721	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	722	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	723	will try it's best to deliver signals synchronously, i.e. as part of the
571	normal event processing, like any other event.	724	normal event processing, like any other event.
572		725
573	You cna configure as many watchers as you like per signal. Only when the	726	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	727	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	728	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	729	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	730	watcher for a signal is stopped libev will reset the signal handler to
578	SIG_DFL (regardless of what it was set to before).	731	SIG_DFL (regardless of what it was set to before).
…		…
586	Configures the watcher to trigger on the given signal number (usually one	739	Configures the watcher to trigger on the given signal number (usually one
587	of the C<SIGxxx> constants).	740	of the C<SIGxxx> constants).
588		741
589	=back	742	=back
590		743
591	=head2 ev_child - wait for pid status changes	744	=head2 C<ev_child> - wait for pid status changes
592		745
593	Child watchers trigger when your process receives a SIGCHLD in response to	746	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).	747	some child status changes (most typically when a child of yours dies).
595		748
596	=over 4	749	=over 4
…		…
600	=item ev_child_set (ev_child *, int pid)	753	=item ev_child_set (ev_child *, int pid)
601		754
602	Configures the watcher to wait for status changes of process C<pid> (or	755	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	756	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	757	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	758	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.	759	C<waitpid> documentation). The C<rpid> member contains the pid of the
		760	process causing the status change.
607		761
608	=back	762	=back
609		763
610	=head2 ev_idle - when you've got nothing better to do	764	=head2 C<ev_idle> - when you've got nothing better to do
611		765
612	Idle watchers trigger events when there are no other I/O or timer (or	766	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	767	(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	768	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	769	imagine) it will not be triggered. But when your process is idle all idle
		770	watchers are being called again and again, once per event loop iteration -
616	stopped, that is, or your process receives more events.	771	until stopped, that is, or your process receives more events and becomes
		772	busy.
617		773
618	The most noteworthy effect is that as long as any idle watchers are	774	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.	775	active, the process will not block when waiting for new events.
620		776
621	Apart from keeping your process non-blocking (which is a useful	777	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,	787	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
632	believe me.	788	believe me.
633		789
634	=back	790	=back
635		791
636	=head2 prepare and check - your hooks into the event loop	792	=head2 C<ev_prepare> and C<ev_check> - customise your event loop
637		793
638	Prepare and check watchers usually (but not always) are used in	794	Prepare and check watchers are usually (but not always) used in tandem:
639	tandom. Prepare watchers get invoked before the process blocks and check	795	prepare watchers get invoked before the process blocks and check watchers
640	watchers afterwards.	796	afterwards.
641		797
642	Their main purpose is to integrate other event mechanisms into libev. This	798	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	799	could be used, for example, to track variable changes, implement your own
644	watchers, integrate net-snmp or a coroutine library and lots more.	800	watchers, integrate net-snmp or a coroutine library and lots more.
645		801
646	This is done by examining in each prepare call which file descriptors need	802	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	803	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	804	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	805	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)	806	any events that occured (by checking the pending status of all watchers
651	and call back into the library.	807	and stopping them) and call back into the library. The I/O and timer
		808	callbacks will never actually be called (but must be valid nevertheless,
		809	because you never know, you know?).
652		810
653	As another example, the perl Coro module uses these hooks to integrate	811	As another example, the Perl Coro module uses these hooks to integrate
654	coroutines into libev programs, by yielding to other active coroutines	812	coroutines into libev programs, by yielding to other active coroutines
655	during each prepare and only letting the process block if no coroutines	813	during each prepare and only letting the process block if no coroutines
656	are ready to run.	814	are ready to run (it's actually more complicated: it only runs coroutines
		815	with priority higher than or equal to the event loop and one coroutine
		816	of lower priority, but only once, using idle watchers to keep the event
		817	loop from blocking if lower-priority coroutines are active, thus mapping
		818	low-priority coroutines to idle/background tasks).
657		819
658	=over 4	820	=over 4
659		821
660	=item ev_prepare_init (ev_prepare *, callback)	822	=item ev_prepare_init (ev_prepare *, callback)
661		823
662	=item ev_check_init (ev_check *, callback)	824	=item ev_check_init (ev_check *, callback)
663		825
664	Initialises and configures the prepare or check watcher - they have no	826	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>	827	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
666	macros, but using them is utterly, utterly pointless.	828	macros, but using them is utterly, utterly and completely pointless.
667		829
668	=back	830	=back
669		831
670	=head1 OTHER FUNCTIONS	832	=head1 OTHER FUNCTIONS
671		833
672	There are some other fucntions of possible interest. Described. Here. Now.	834	There are some other functions of possible interest. Described. Here. Now.
673		835
674	=over 4	836	=over 4
675		837
676	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	838	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
677		839
678	This function combines a simple timer and an I/O watcher, calls your	840	This function combines a simple timer and an I/O watcher, calls your
679	callback on whichever event happens first and automatically stop both	841	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	842	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	843	or timeout without having to allocate/configure/start/stop/free one or
682	more watchers yourself.	844	more watchers yourself.
683		845
684	If C<fd> is less than 0, then no I/O watcher will be started and events is	846	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	847	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
686	will be craeted and started.	848	C<events> set will be craeted and started.
687		849
688	If C<timeout> is less than 0, then no timeout watcher will be	850	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	851	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
690	= 0) will be started.	852	repeat = 0) will be started. While C<0> is a valid timeout, it is of
		853	dubious value.
691		854
692	The callback has the type C<void (cb)(int revents, void arg)> and	855	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,	856	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>:	857	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
		858	value passed to C<ev_once>:
695		859
696	static void stdin_ready (int revents, void *arg)	860	static void stdin_ready (int revents, void *arg)
697	{	861	{
698	if (revents & EV_TIMEOUT)	862	if (revents & EV_TIMEOUT)
699	/* doh, nothing entered */	863	/* doh, nothing entered */;
700	else if (revents & EV_READ)	864	else if (revents & EV_READ)
701	/* stdin might have data for us, joy! */	865	/* stdin might have data for us, joy! */;
702	}	866	}
703		867
704	ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0);	868	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
705		869
706	=item ev_feed_event (loop, watcher, int events)	870	=item ev_feed_event (loop, watcher, int events)
707		871
708	Feeds the given event set into the event loop, as if the specified event	872	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	873	had happened for the specified watcher (which must be a pointer to an
710	initialised but not necessarily active event watcher).	874	initialised but not necessarily started event watcher).
711		875
712	=item ev_feed_fd_event (loop, int fd, int revents)	876	=item ev_feed_fd_event (loop, int fd, int revents)
713		877
714	Feed an event on the given fd, as if a file descriptor backend detected it.	878	Feed an event on the given fd, as if a file descriptor backend detected
		879	the given events it.
715		880
716	=item ev_feed_signal_event (loop, int signum)	881	=item ev_feed_signal_event (loop, int signum)
717		882
718	Feed an event as if the given signal occured (loop must be the default loop!).	883	Feed an event as if the given signal occured (loop must be the default loop!).
719		884
720	=back	885	=back
721		886
		887	=head1 LIBEVENT EMULATION
		888
		889	Libev offers a compatibility emulation layer for libevent. It cannot
		890	emulate the internals of libevent, so here are some usage hints:
		891
		892	=over 4
		893
		894	=item * Use it by including <event.h>, as usual.
		895
		896	=item * The following members are fully supported: ev_base, ev_callback,
		897	ev_arg, ev_fd, ev_res, ev_events.
		898
		899	=item * Avoid using ev_flags and the EVLIST_*-macros, while it is
		900	maintained by libev, it does not work exactly the same way as in libevent (consider
		901	it a private API).
		902
		903	=item * Priorities are not currently supported. Initialising priorities
		904	will fail and all watchers will have the same priority, even though there
		905	is an ev_pri field.
		906
		907	=item * Other members are not supported.
		908
		909	=item * The libev emulation is I<not> ABI compatible to libevent, you need
		910	to use the libev header file and library.
		911
		912	=back
		913
		914	=head1 C++ SUPPORT
		915
		916	TBD.
		917
722	=head1 AUTHOR	918	=head1 AUTHOR
723		919
724	Marc Lehmann <libev@schmorp.de>.	920	Marc Lehmann <libev@schmorp.de>.
725		921

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Revision 1.1 by root, Mon Nov 12 07:58:13 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC