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

Comparing libev/ev.pod (file contents):
Revision 1.3 by root, Mon Nov 12 08:03:31 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, representing the	46	Libev represents time as a single floating point number, representing the
45	(fractional) number of seconds since the (POSIX) epoch (somewhere near	47	(fractional) number of seconds since the (POSIX) epoch (somewhere near
46	the beginning of 1970, details are complicated, don't ask). This type is	48	the beginning of 1970, details are complicated, don't ask). This type is
47	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
48	to the double type in C.	50	to the double type in C.
49		51
		52	=head1 GLOBAL FUNCTIONS
		53
		54	These functions can be called anytime, even before initialising the
		55	library in any way.
		56
50	=over 4	57	=over 4
51		58
52	=item ev_tstamp ev_time ()	59	=item ev_tstamp ev_time ()
53		60
54	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.
55		64
56	=item int ev_version_major ()	65	=item int ev_version_major ()
57		66
58	=item int ev_version_minor ()	67	=item int ev_version_minor ()
59		68
…		…
61	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
62	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
63	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
64	version of the library your program was compiled against.	73	version of the library your program was compiled against.
65		74
66	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,
67	as this indicates an incompatible change. Minor versions are usually	76	as this indicates an incompatible change. Minor versions are usually
68	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
69	not a problem.	78	not a problem.
70		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
71	=item ev_set_allocator (void (cb)(void *ptr, long size))	96	=item ev_set_allocator (void (cb)(void *ptr, long size))
72		97
73	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
74	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
75	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
76	might abort or take some potentially destructive action. The default is	101	needs to be allocated, the library might abort or take some potentially
77	your system realloc function.	102	destructive action. The default is your system realloc function.
78		103
79	You could override this function in high-availability programs to, say,	104	You could override this function in high-availability programs to, say,
80	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,
81	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.
82		107
…		…
84		109
85	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
86	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
87	indicating the system call or subsystem causing the problem. If this	112	indicating the system call or subsystem causing the problem. If this
88	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
89	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
90	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
91	(such as abort).	116	(such as abort).
92		117
93	=back	118	=back
94		119
…		…
97	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
98	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
99	events, and dynamically created loops which do not.	124	events, and dynamically created loops which do not.
100		125
101	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
102	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
103	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
104	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
105	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).
106		132
107	=over 4	133	=over 4
108		134
109	=item struct ev_loop *ev_default_loop (unsigned int flags)	135	=item struct ev_loop *ev_default_loop (unsigned int flags)
110		136
111	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
112	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
113	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
114	flags).	140	flags. If that is troubling you, check C<ev_backend ()> afterwards).
115		141
116	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
117	function.	143	function.
118		144
119	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
120	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).
121		147
122	It supports the following flags:	148	It supports the following flags:
123		149
124	=over 4	150	=over 4
125		151
126	=item EVFLAG_AUTO	152	=item C<EVFLAG_AUTO>
127		153
128	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
129	thing, believe me).	155	thing, believe me).
130		156
131	=item EVFLAG_NOENV	157	=item C<EVFLAG_NOENV>
132		158
133	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
134	at the environment variable C<LIBEV_FLAGS>. Otherwise (the default), this	160	or setgid) then libev will I<not> look at the environment variable
135	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
136	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
137	bugs.	164	around bugs.
138		165
139	=item EVMETHOD_SELECT portable select backend	166	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
140		167
141	=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.
142		173
143	=item EVMETHOD_EPOLL linux only	174	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
144		175
145	=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).
146		180
147	=item EVMETHOD_DEVPOLL solaris 8 only	181	=item C<EVBACKEND_EPOLL> (value 4, Linux)
148		182
149	=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
150		232
151	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
152	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
153	specified, any backend will do.	235	specified, most compiled-in backend will be tried, usually in reverse
154		236	order of their flag values :)
155	=back
156		237
157	=item struct ev_loop *ev_loop_new (unsigned int flags)	238	=item struct ev_loop *ev_loop_new (unsigned int flags)
158		239
159	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
160	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
…		…
163		244
164	=item ev_default_destroy ()	245	=item ev_default_destroy ()
165		246
166	Destroys the default loop again (frees all memory and kernel state	247	Destroys the default loop again (frees all memory and kernel state
167	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
168	any way whatsoever, although you cnanot rely on this :).	249	any way whatsoever, although you cannot rely on this :).
169		250
170	=item ev_loop_destroy (loop)	251	=item ev_loop_destroy (loop)
171		252
172	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
173	earlier call to C<ev_loop_new>.	254	earlier call to C<ev_loop_new>.
…		…
177	This function reinitialises the kernel state for backends that have	258	This function reinitialises the kernel state for backends that have
178	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
179	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
180	again makes little sense).	261	again makes little sense).
181		262
182	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
183	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
184	have to call it.	265	fork+exec, you don't have to call it.
185		266
186	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
187	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
188	quite nicely into a call to C<pthread_atfork>:	269	quite nicely into a call to C<pthread_atfork>:
189		270
190	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.
191		276
192	=item ev_loop_fork (loop)	277	=item ev_loop_fork (loop)
193		278
194	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
195	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
196	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.
197		282
198	=item unsigned int ev_method (loop)	283	=item unsigned int ev_backend (loop)
199		284
200	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
201	use.	286	use.
202		287
203	=item ev_tstamp = ev_now (loop)	288	=item ev_tstamp ev_now (loop)
204		289
205	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
206	got events and started processing them. This timestamp does not change	291	got events and started processing them. This timestamp does not change
207	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
208	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
…		…
217	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
218	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.
219		304
220	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
221	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
222	case there are no events.	307	case there are no events and will return after one iteration of the loop.
223		308
224	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
225	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
226	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.
227		313
228	This flags value could be used to implement alternative looping	314	This flags value could be used to implement alternative looping
229	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
230	more generic mechanism.	316	more generic mechanism.
231		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
232	=item ev_unloop (loop, how)	336	=item ev_unloop (loop, how)
233		337
234	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
235	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
236	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.
237	calls return.
238		342
239	=item ev_ref (loop)	343	=item ev_ref (loop)
240		344
241	=item ev_unref (loop)	345	=item ev_unref (loop)
242		346
243	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
244	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
245	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
246	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
247	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
248	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
249	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
250	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
251	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>.
252		357
253	=back	358	=back
254		359
255	=head1 ANATOMY OF A WATCHER	360	=head1 ANATOMY OF A WATCHER
256		361
257	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
258	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
259	become readable, you would create an ev_io watcher for that:	364	become readable, you would create an C<ev_io> watcher for that:
260		365
261	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)
262	{	367	{
263	ev_io_stop (w);	368	ev_io_stop (w);
264	ev_unloop (loop, EVUNLOOP_ALL);	369	ev_unloop (loop, EVUNLOOP_ALL);
…		…
291	*) >>), 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
292	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	397	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
293		398
294	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
295	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
296	reinitialise it or call its set method.	401	reinitialise it or call its set macro.
297		402
298	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
299	(watcher *)> macro. To see wether an event is outstanding (but the	404	(watcher *)> macro. To see whether an event is outstanding (but the
300	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
301	(watcher *)> macro.	406	(watcher *)> macro.
302		407
303	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
304	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
305	third argument.	410	third argument.
306		411
307	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
308	(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
309	are:	414	are:
310		415
311	=over 4	416	=over 4
312		417
313	=item EV_READ	418	=item C<EV_READ>
314		419
315	=item EV_WRITE	420	=item C<EV_WRITE>
316		421
317	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
318	writable.	423	writable.
319		424
320	=item EV_TIMEOUT	425	=item C<EV_TIMEOUT>
321		426
322	The ev_timer watcher has timed out.	427	The C<ev_timer> watcher has timed out.
323		428
324	=item EV_PERIODIC	429	=item C<EV_PERIODIC>
325		430
326	The ev_periodic watcher has timed out.	431	The C<ev_periodic> watcher has timed out.
327		432
328	=item EV_SIGNAL	433	=item C<EV_SIGNAL>
329		434
330	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.
331		436
332	=item EV_CHILD	437	=item C<EV_CHILD>
333		438
334	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.
335		440
336	=item EV_IDLE	441	=item C<EV_IDLE>
337		442
338	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.
339		444
340	=item EV_PREPARE	445	=item C<EV_PREPARE>
341		446
342	=item EV_CHECK	447	=item C<EV_CHECK>
343		448
344	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
345	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
346	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
347	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
348	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
349	(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
350	C<ev_loop> from blocking).	455	C<ev_loop> from blocking).
351		456
352	=item EV_ERROR	457	=item C<EV_ERROR>
353		458
354	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
355	happen because the watcher could not be properly started because libev	460	happen because the watcher could not be properly started because libev
356	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
357	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
…		…
366	=back	471	=back
367		472
368	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	473	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
369		474
370	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
371	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
372	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
373	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
374	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
375	data:	480	data:
376		481
…		…
398	=head1 WATCHER TYPES	503	=head1 WATCHER TYPES
399		504
400	This section describes each watcher in detail, but will not repeat	505	This section describes each watcher in detail, but will not repeat
401	information given in the last section.	506	information given in the last section.
402		507
403	=head2 struct ev_io - is my file descriptor readable or writable	508	=head2 C<ev_io> - is this file descriptor readable or writable
404		509
405	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
406	in each iteration of the event loop (This behaviour is called	511	in each iteration of the event loop (This behaviour is called
407	level-triggering because you keep receiving events as long as the	512	level-triggering because you keep receiving events as long as the
408	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
409	act on the event and neither want to receive future events).	514	act on the event and neither want to receive future events).
410		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
411	=over 4	531	=over 4
412		532
413	=item ev_io_init (ev_io *, callback, int fd, int events)	533	=item ev_io_init (ev_io *, callback, int fd, int events)
414		534
415	=item ev_io_set (ev_io *, int fd, int events)	535	=item ev_io_set (ev_io *, int fd, int events)
416		536
417	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
418	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 \|
419	EV_WRITE> to receive the given events.	539	EV_WRITE> to receive the given events.
420		540
421	=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.
422		551
		552	=back
		553
423	=head2 struct ev_timer - relative and optionally recurring timeouts	554	=head2 C<ev_timer> - relative and optionally recurring timeouts
424		555
425	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
426	given time, and optionally repeating in regular intervals after that.	557	given time, and optionally repeating in regular intervals after that.
427		558
428	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
429	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
430	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
431	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	562	detecting time jumps is hard, and some inaccuracies are unavoidable (the
432	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.
433		576
434	=over 4	577	=over 4
435		578
436	=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)
437		580
…		…
443	later, again, and again, until stopped manually.	586	later, again, and again, until stopped manually.
444		587
445	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
446	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
447	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
448	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
449	timer will not fire more than once per event loop iteration.	592	timer will not fire more than once per event loop iteration.
450		593
451	=item ev_timer_again (loop)	594	=item ev_timer_again (loop)
452		595
453	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
…		…
460		603
461	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
462	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
463	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
464	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
465	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
466	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
467	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
468	the timer, and again will automatically restart it if need be.	611	the timer, and again will automatically restart it if need be.
469		612
470	=back	613	=back
471		614
472	=head2 ev_periodic - to cron or not to cron it	615	=head2 C<ev_periodic> - to cron or not to cron
473		616
474	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
475	(and unfortunately a bit complex).	618	(and unfortunately a bit complex).
476		619
477	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)
478	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
479	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
480	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 ()
481	+ 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
482	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
483	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
484	again).	627	again).
485		628
486	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
487	triggering an event on eahc midnight, local time.	630	triggering an event on eahc midnight, local time.
488		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
489	=over 4	636	=over 4
490		637
491	=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)
492		639
493	=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)
494		641
495	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
496	operation, and we will explain them from simplest to complex:	643	operation, and we will explain them from simplest to complex:
497
498		644
499	=over 4	645	=over 4
500		646
501	=item * absolute timer (interval = reschedule_cb = 0)	647	=item * absolute timer (interval = reschedule_cb = 0)
502		648
…		…
516		662
517	ev_periodic_set (&periodic, 0., 3600., 0);	663	ev_periodic_set (&periodic, 0., 3600., 0);
518		664
519	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,
520	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
521	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
522	by 3600.	668	by 3600.
523		669
524	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
525	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
526	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.
527		673
528	=item * manual reschedule mode (reschedule_cb = callback)	674	=item * manual reschedule mode (reschedule_cb = callback)
529		675
530	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
531	ignored. Instead, each time the periodic watcher gets scheduled, the	677	ignored. Instead, each time the periodic watcher gets scheduled, the
532	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
533	current time as second argument.	679	current time as second argument.
534		680
535	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,
536	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,
537	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).
538		685
539	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,
540	ev_tstamp now)>, e.g.:	687	ev_tstamp now)>, e.g.:
541		688
542	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)
543	{	690	{
544	return now + 60.;	691	return now + 60.;
…		…
547	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
548	(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
549	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
550	might be called at other times, too.	697	might be called at other times, too.
551		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
552	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
553	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
554	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
555	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).
556		707
557	=back	708	=back
558		709
559	=item ev_periodic_again (loop, ev_periodic *)	710	=item ev_periodic_again (loop, ev_periodic *)
560		711
…		…
563	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
564	program when the crontabs have changed).	715	program when the crontabs have changed).
565		716
566	=back	717	=back
567		718
568	=head2 ev_signal - signal me when a signal gets signalled	719	=head2 C<ev_signal> - signal me when a signal gets signalled
569		720
570	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
571	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
572	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
573	normal event processing, like any other event.	724	normal event processing, like any other event.
574		725
575	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
576	first watcher gets started will libev actually register a signal watcher	727	first watcher gets started will libev actually register a signal watcher
577	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
578	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
579	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
580	SIG_DFL (regardless of what it was set to before).	731	SIG_DFL (regardless of what it was set to before).
…		…
588	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
589	of the C<SIGxxx> constants).	740	of the C<SIGxxx> constants).
590		741
591	=back	742	=back
592		743
593	=head2 ev_child - wait for pid status changes	744	=head2 C<ev_child> - wait for pid status changes
594		745
595	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
596	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).
597		748
598	=over 4	749	=over 4
…		…
602	=item ev_child_set (ev_child *, int pid)	753	=item ev_child_set (ev_child *, int pid)
603		754
604	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
605	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
606	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
607	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
608	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.
609		761
610	=back	762	=back
611		763
612	=head2 ev_idle - when you've got nothing better to do	764	=head2 C<ev_idle> - when you've got nothing better to do
613		765
614	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
615	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
616	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,
617	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 -
618	stopped, that is, or your process receives more events.	771	until stopped, that is, or your process receives more events and becomes
		772	busy.
619		773
620	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
621	active, the process will not block when waiting for new events.	775	active, the process will not block when waiting for new events.
622		776
623	Apart from keeping your process non-blocking (which is a useful	777	Apart from keeping your process non-blocking (which is a useful
…		…
633	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,
634	believe me.	788	believe me.
635		789
636	=back	790	=back
637		791
638	=head2 prepare and check - your hooks into the event loop	792	=head2 C<ev_prepare> and C<ev_check> - customise your event loop
639		793
640	Prepare and check watchers usually (but not always) are used in	794	Prepare and check watchers are usually (but not always) used in tandem:
641	tandom. Prepare watchers get invoked before the process blocks and check	795	prepare watchers get invoked before the process blocks and check watchers
642	watchers afterwards.	796	afterwards.
643		797
644	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
645	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
646	watchers, integrate net-snmp or a coroutine library and lots more.	800	watchers, integrate net-snmp or a coroutine library and lots more.
647		801
648	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
649	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
650	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
651	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
652	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
653	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?).
654		810
655	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
656	coroutines into libev programs, by yielding to other active coroutines	812	coroutines into libev programs, by yielding to other active coroutines
657	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
658	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).
659		819
660	=over 4	820	=over 4
661		821
662	=item ev_prepare_init (ev_prepare *, callback)	822	=item ev_prepare_init (ev_prepare *, callback)
663		823
664	=item ev_check_init (ev_check *, callback)	824	=item ev_check_init (ev_check *, callback)
665		825
666	Initialises and configures the prepare or check watcher - they have no	826	Initialises and configures the prepare or check watcher - they have no
667	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>
668	macros, but using them is utterly, utterly pointless.	828	macros, but using them is utterly, utterly and completely pointless.
669		829
670	=back	830	=back
671		831
672	=head1 OTHER FUNCTIONS	832	=head1 OTHER FUNCTIONS
673		833
674	There are some other fucntions of possible interest. Described. Here. Now.	834	There are some other functions of possible interest. Described. Here. Now.
675		835
676	=over 4	836	=over 4
677		837
678	=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)
679		839
680	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
681	callback on whichever event happens first and automatically stop both	841	callback on whichever event happens first and automatically stop both
682	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
683	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
684	more watchers yourself.	844	more watchers yourself.
685		845
686	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
687	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
688	will be craeted and started.	848	C<events> set will be craeted and started.
689		849
690	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
691	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
692	= 0) will be started.	852	repeat = 0) will be started. While C<0> is a valid timeout, it is of
		853	dubious value.
693		854
694	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
695	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
696	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>:
697		859
698	static void stdin_ready (int revents, void *arg)	860	static void stdin_ready (int revents, void *arg)
699	{	861	{
700	if (revents & EV_TIMEOUT)	862	if (revents & EV_TIMEOUT)
701	/* doh, nothing entered */	863	/* doh, nothing entered */;
702	else if (revents & EV_READ)	864	else if (revents & EV_READ)
703	/* stdin might have data for us, joy! */	865	/* stdin might have data for us, joy! */;
704	}	866	}
705		867
706	ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0);	868	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
707		869
708	=item ev_feed_event (loop, watcher, int events)	870	=item ev_feed_event (loop, watcher, int events)
709		871
710	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
711	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
712	initialised but not necessarily active event watcher).	874	initialised but not necessarily started event watcher).
713		875
714	=item ev_feed_fd_event (loop, int fd, int revents)	876	=item ev_feed_fd_event (loop, int fd, int revents)
715		877
716	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.
717		880
718	=item ev_feed_signal_event (loop, int signum)	881	=item ev_feed_signal_event (loop, int signum)
719		882
720	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!).
721		884
722	=back	885	=back
723		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
724	=head1 AUTHOR	918	=head1 AUTHOR
725		919
726	Marc Lehmann <libev@schmorp.de>.	920	Marc Lehmann <libev@schmorp.de>.
727		921

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Comparing libev/ev.pod (file contents): Revision 1.3 by root, Mon Nov 12 08:03:31 2007 UTC vs. Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC

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Revision 1.3 by root, Mon Nov 12 08:03:31 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC