[ViewVC] Diff of: cvs/EV/EV.pm

Comparing EV/EV.pm (file contents):
Revision 1.18 by root, Thu Nov 1 08:10:03 2007 UTC vs.
Revision 1.51 by root, Sat Nov 24 16:12:37 2007 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
22	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
23	};	23	};
24		24
25	# IO	25	# IO
26		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $revents) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($revents & EV::TIMEOUT) {
30	warn "nothing received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};
35	$w->timeout (10);
36
37	my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
38	my ($w, $revents) = @_;
39	if ($revents & EV::TIMEOUT) {
40	warn "nothing entered within 30 seconds, bye bye.\n";
41	$w->stop;
42	} else {
43	my $line = <STDIN>;
44	warn "you entered something, you again have 30 seconds.\n";
45	}
46	};	30	};
47		31
48	# SIGNALS	32	# SIGNALS
49		33
50	my $w = EV::signal 'QUIT', sub {	34	my $w = EV::signal 'QUIT', sub {
51	warn "sigquit received\n";	35	warn "sigquit received\n";
52	};	36	};
53		37
		38	# CHILD/PID STATUS CHANGES
		39
54	my $w = EV::signal 3, sub {	40	my $w = EV::child 666, sub {
55	warn "sigquit received (this is GNU/Linux, right?)\n";	41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
56	};	43	};
57
58	# CHILD/PID STATUS CHANGES
59
60	my $w = EV::child 666, sub {
61	my ($w, $revents, $status) = @_;
62	};
63		44
64	# MAINLOOP	45	# MAINLOOP
65	EV::dispatch; # loop as long as watchers are active	46	EV::loop; # loop until EV::unloop is called or all watchers stop
66	EV::loop; # the same thing
67	EV::loop EV::LOOP_ONESHOT; # block until some events could be handles	47	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
68	EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait	48	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
69		49
70	=head1 DESCRIPTION	50	=head1 DESCRIPTION
71		51
72	This module provides an interface to libev	52	This module provides an interface to libev
73	(L<http://software.schmorp.de/pkg/libev.html>). You probably should	53	(L<http://software.schmorp.de/pkg/libev.html>).
74	acquaint yourself with its documentation and source code to be able to use
75	this module fully.
76		54
77	=cut	55	=cut
78		56
79	package EV;	57	package EV;
80		58
81	use strict;	59	use strict;
82		60
83	BEGIN {	61	BEGIN {
84	our $VERSION = '0.03';	62	our $VERSION = '1.3';
85	use XSLoader;	63	use XSLoader;
86	XSLoader::load "EV", $VERSION;	64	XSLoader::load "EV", $VERSION;
87	}	65	}
88		66
89	@EV::Io::ISA =	67	@EV::IO::ISA =
90	@EV::Timer::ISA =	68	@EV::Timer::ISA =
91	@EV::Periodic::ISA =	69	@EV::Periodic::ISA =
92	@EV::Signal::ISA =	70	@EV::Signal::ISA =
93	@EV::Idle::ISA =	71	@EV::Idle::ISA =
94	@EV::Prepare::ISA =	72	@EV::Prepare::ISA =
97		75
98	=head1 BASIC INTERFACE	76	=head1 BASIC INTERFACE
99		77
100	=over 4	78	=over 4
101		79
102	=item $EV::NPRI
103
104	How many priority levels are available.
105
106	=item $EV::DIED	80	=item $EV::DIED
107		81
108	Must contain a reference to a function that is called when a callback	82	Must contain a reference to a function that is called when a callback
109	throws an exception (with $@ containing thr error). The default prints an	83	throws an exception (with $@ containing thr error). The default prints an
110	informative message and continues.	84	informative message and continues.
111		85
112	If this callback throws an exception it will be silently ignored.	86	If this callback throws an exception it will be silently ignored.
113		87
		88	=item $time = EV::time
		89
		90	Returns the current time in (fractional) seconds since the epoch.
		91
114	=item $time = EV::now	92	=item $time = EV::now
115		93
116	Returns the time in (fractional) seconds since the epoch.	94	Returns the time the last event loop iteration has been started. This
117		95	is the time that (relative) timers are based on, and refering to it is
118	=item $version = EV::version	96	usually faster then calling EV::time.
119		97
120	=item $method = EV::method	98	=item $method = EV::method
121		99
122	Return version string and event polling method used.	100	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		101	or EV::METHOD_EPOLL).
123		102
124	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	103	=item EV::loop [$flags]
125		104
126	=item EV::loopexit $after	105	Begin checking for events and calling callbacks. It returns when a
		106	callback calls EV::unloop.
127		107
128	Exit any active loop or dispatch after C<$after> seconds or immediately if	108	The $flags argument can be one of the following:
129	C<$after> is missing or zero.
130		109
131	=item EV::dispatch	110	0 as above
		111	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		112	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
132		113
133	Same as C<EV::loop 0>.	114	=item EV::unloop [$how]
134		115
135	=item EV::event $callback	116	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		117	innermost call to EV::loop return.
136		118
137	Creates a new event watcher waiting for nothing, calling the given callback.	119	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		120	fast as possible.
138		121
		122	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		123
		124	This function rolls together an I/O and a timer watcher for a single
		125	one-shot event without the need for managing a watcher object.
		126
		127	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		128	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		129	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		130	you do not want to wait for some I/O event, specify C<undef> for
		131	C<$fh_or_undef> and C<0> for C<$events>).
		132
		133	If timeout is C<undef> or negative, then there will be no
		134	timeout. Otherwise a EV::timer with this value will be started.
		135
		136	When an error occurs or either the timeout or I/O watcher triggers, then
		137	the callback will be called with the received event set (in general
		138	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		139	C<EV::WRITE> and C<EV::TIMEOUT>).
		140
		141	EV::once doesn't return anything: the watchers stay active till either
		142	of them triggers, then they will be stopped and freed, and the callback
		143	invoked.
		144
		145	=back
		146
		147	=head2 WATCHER
		148
		149	A watcher is an object that gets created to record your interest in some
		150	event. For instance, if you want to wait for STDIN to become readable, you
		151	would create an EV::io watcher for that:
		152
		153	my $watcher = EV::io *STDIN, EV::READ, sub {
		154	my ($watcher, $revents) = @_;
		155	warn "yeah, STDIN should not be readable without blocking!\n"
		156	};
		157
		158	All watchers can be active (waiting for events) or inactive (paused). Only
		159	active watchers will have their callbacks invoked. All callbacks will be
		160	called with at least two arguments: the watcher and a bitmask of received
		161	events.
		162
		163	Each watcher type has its associated bit in revents, so you can use the
		164	same callback for multiple watchers. The event mask is named after the
		165	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		166	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		167	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		168	uses EV::TIMEOUT).
		169
		170	In the rare case where one wants to create a watcher but not start it at
		171	the same time, each constructor has a variant with a trailing C<_ns> in
		172	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		173
		174	Please note that a watcher will automatically be stopped when the watcher
		175	object is destroyed, so you I<need> to keep the watcher objects returned by
		176	the constructors.
		177
		178	Also, all methods changing some aspect of a watcher (->set, ->priority,
		179	->fh and so on) automatically stop and start it again if it is active,
		180	which means pending events get lost.
		181
		182	=head2 WATCHER TYPES
		183
		184	Now lets move to the existing watcher types and asociated methods.
		185
		186	The following methods are available for all watchers. Then followes a
		187	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
		188	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
		189	any type-specific methods (if any).
		190
		191	=over 4
		192
		193	=item $w->start
		194
		195	Starts a watcher if it isn't active already. Does nothing to an already
		196	active watcher. By default, all watchers start out in the active state
		197	(see the description of the C<_ns> variants if you need stopped watchers).
		198
		199	=item $w->stop
		200
		201	Stop a watcher if it is active. Also clear any pending events (events that
		202	have been received but that didn't yet result in a callback invocation),
		203	regardless of wether the watcher was active or not.
		204
		205	=item $bool = $w->is_active
		206
		207	Returns true if the watcher is active, false otherwise.
		208
		209	=item $current_data = $w->data
		210
		211	=item $old_data = $w->data ($new_data)
		212
		213	Queries a freely usable data scalar on the watcher and optionally changes
		214	it. This is a way to associate custom data with a watcher:
		215
		216	my $w = EV::timer 60, 0, sub {
		217	warn $_[0]->data;
		218	};
		219	$w->data ("print me!");
		220
		221	=item $current_cb = $w->cb
		222
		223	=item $old_cb = $w->cb ($new_cb)
		224
		225	Queries the callback on the watcher and optionally changes it. You can do
		226	this at any time without the watcher restarting.
		227
		228	=item $current_priority = $w->priority
		229
		230	=item $old_priority = $w->priority ($new_priority)
		231
		232	Queries the priority on the watcher and optionally changes it. Pending
		233	watchers with higher priority will be invoked first. The valid range of
		234	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		235	-2). If the priority is outside this range it will automatically be
		236	normalised to the nearest valid priority.
		237
		238	The default priority of any newly-created watcher is 0.
		239
		240	Note that the priority semantics have not yet been fleshed out and are
		241	subject to almost certain change.
		242
		243	=item $w->trigger ($revents)
		244
		245	Call the callback now with the given event mask.
		246
		247	=item $previous_state = $w->keepalive ($bool)
		248
		249	Normally, C<EV::loop> will return when there are no active watchers
		250	(which is a "deadlock" because no progress can be made anymore). This is
		251	convinient because it allows you to start your watchers (and your jobs),
		252	call C<EV::loop> once and when it returns you know that all your jobs are
		253	finished (or they forgot to register some watchers for their task :).
		254
		255	Sometimes, however, this gets in your way, for example when you the module
		256	that calls C<EV::loop> (usually the main program) is not the same module
		257	as a long-living watcher (for example a DNS client module written by
		258	somebody else even). Then you might want any outstanding requests to be
		259	handled, but you would not want to keep C<EV::loop> from returning just
		260	because you happen to have this long-running UDP port watcher.
		261
		262	In this case you can clear the keepalive status, which means that even
		263	though your watcher is active, it won't keep C<EV::loop> from returning.
		264
		265	The initial value for keepalive is true (enabled), and you cna change it
		266	any time.
		267
		268	Example: Register an IO watcher for some UDP socket but do not keep the
		269	event loop from running just because of that watcher.
		270
		271	my $udp_socket = ...
		272	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		273	$udp_watcher->keepalive (0);
		274
139	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	275	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
140		276
141	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	277	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
142		278
143	As long as the returned watcher object is alive, call the C<$callback>	279	As long as the returned watcher object is alive, call the C<$callback>
144	when the events specified in C<$eventmask> happen. Initially, the timeout	280	when the events specified in C<$eventmask>.
145	is disabled.
146		281
147	You can additionall set a timeout to occur on the watcher, but note that
148	this timeout will not be reset when you get an I/O event in the EV::PERSIST
149	case, and reaching a timeout will always stop the watcher even in the
150	EV::PERSIST case.
151
152	If you want a timeout to occur only after a specific time of inactivity, set
153	a repeating timeout and do NOT use EV::PERSIST.
154
155	Eventmask can be one or more of these constants ORed together:	282	The $eventmask can be one or more of these constants ORed together:
156		283
157	EV::READ wait until read() wouldn't block anymore	284	EV::READ wait until read() wouldn't block anymore
158	EV::WRITE wait until write() wouldn't block anymore	285	EV::WRITE wait until write() wouldn't block anymore
159	EV::PERSIST stay active after a (non-timeout) event occured
160		286
161	The C<io_ns> variant doesn't add/start the newly created watcher.	287	The C<io_ns> variant doesn't start (activate) the newly created watcher.
162		288
163	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	289	=item $w->set ($fileno_or_fh, $eventmask)
164		290
165	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	291	Reconfigures the watcher, see the constructor above for details. Can be
		292	called at any time.
166		293
167	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	294	=item $current_fh = $w->fh
168	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
169	and will automatically be cleared. The watcher will be restarted after each event.
170		295
171	If the timeout is zero or undef, no timeout will be set, and a normal	296	=item $old_fh = $w->fh ($new_fh)
172	watcher (with the persist flag set!) will be created.
173		297
174	This has the effect of timing out after the specified period of inactivity	298	Returns the previously set filehandle and optionally set a new one.
175	has happened.
176		299
177	Due to the design of libevent, this is also relatively inefficient, having	300	=item $current_eventmask = $w->events
178	one or two io watchers and a separate timeout watcher that you reset on
179	activity (by calling its C<start> method) is usually more efficient.
180		301
		302	=item $old_eventmask = $w->events ($new_eventmask)
		303
		304	Returns the previously set event mask and optionally set a new one.
		305
		306
181	=item my $w = EV::timer $after, $repeat, $callback	307	=item $w = EV::timer $after, $repeat, $callback
182		308
183	=item my $w = EV::timer_ns $after, $repeat, $callback	309	=item $w = EV::timer_ns $after, $repeat, $callback
184		310
185	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	311	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,
186	timer will be restarted after the callback returns. This means that the	312	the timer will be restarted (with the $repeat value as $after) after the
187	callback would be called roughly every C<$after> seconds, prolonged by the	313	callback returns.
188	time the callback takes.
189		314
		315	This means that the callback would be called roughly after C<$after>
		316	seconds, and then every C<$repeat> seconds. The timer does his best not
		317	to drift, but it will not invoke the timer more often then once per event
		318	loop iteration, and might drift in other cases. If that isn't acceptable,
		319	look at EV::periodic, which can provide long-term stable timers.
		320
		321	The timer is based on a monotonic clock, that is, if somebody is sitting
		322	in front of the machine while the timer is running and changes the system
		323	clock, the timer will nevertheless run (roughly) the same time.
		324
190	The C<timer_ns> variant doesn't add/start the newly created watcher.	325	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
191		326
192	=item my $w = EV::timer_abs $at, $interval, $callback	327	=item $w->set ($after, $repeat)
193		328
194	=item my $w = EV::timer_abs_ns $at, $interval, $callback	329	Reconfigures the watcher, see the constructor above for details. Can be at
		330	any time.
195		331
196	Similar to EV::timer, but the time is given as an absolute point in time	332	=item $w->again
197	(C<$at>), plus an optional C<$interval>.
198		333
199	If the C<$interval> is zero, then the callback will be called at the time	334	Similar to the C<start> method, but has special semantics for repeating timers:
200	C<$at> if that is in the future, or as soon as possible if its in the
201	past. It will not automatically repeat.
202		335
203	If the C<$interval> is nonzero, then the watcher will always be scheduled	336	If the timer is active and non-repeating, it will be stopped.
204	to time out at the next C<$at + integer * $interval> time.
205		337
206	This can be used to schedule a callback to run at very regular intervals,	338	If the timer is active and repeating, reset the timeout to occur
207	as long as the processing time is less then the interval (otherwise	339	C<$repeat> seconds after now.
208	obviously events will be skipped).	340
		341	If the timer is inactive and repeating, start it using the repeat value.
		342
		343	Otherwise do nothing.
		344
		345	This behaviour is useful when you have a timeout for some IO
		346	operation. You create a timer object with the same value for C<$after> and
		347	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		348	on the timeout.
		349
		350
		351	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		352
		353	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		354
		355	Similar to EV::timer, but is not based on relative timeouts but on
		356	absolute times. Apart from creating "simple" timers that trigger "at" the
		357	specified time, it can also be used for non-drifting absolute timers and
		358	more complex, cron-like, setups that are not adversely affected by time
		359	jumps (i.e. when the system clock is changed by explicit date -s or other
		360	means such as ntpd). It is also the most complex watcher type in EV.
		361
		362	It has three distinct "modes":
		363
		364	=over 4
		365
		366	=item * absolute timer ($interval = $reschedule_cb = 0)
		367
		368	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		369	will not adjust when a time jump occurs, that is, if it is to be run
		370	at January 1st 2011 then it will run when the system time reaches or
		371	surpasses this time.
		372
		373	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		374
		375	In this mode the watcher will always be scheduled to time out at the
		376	next C<$at + N * $interval> time (for some integer N) and then repeat,
		377	regardless of any time jumps.
		378
		379	This can be used to create timers that do not drift with respect to system
		380	time:
		381
		382	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		383
		384	That doesn't mean there will always be 3600 seconds in between triggers,
		385	but only that the the clalback will be called when the system time shows a
		386	full hour (UTC).
209		387
210	Another way to think about it (for the mathematically inclined) is that	388	Another way to think about it (for the mathematically inclined) is that
211	C<timer_abs> will try to tun the callback at the next possible time where	389	EV::periodic will try to run the callback in this mode at the next
212	C<$time = $at (mod $interval)>, regardless of any time jumps.	390	possible time where C<$time = $at (mod $interval)>, regardless of any time
		391	jumps.
213		392
		393	=item * manual reschedule mode ($reschedule_cb = coderef)
		394
		395	In this mode $interval and $at are both being ignored. Instead, each
		396	time the periodic watcher gets scheduled, the reschedule callback
		397	($reschedule_cb) will be called with the watcher as first, and the current
		398	time as second argument.
		399
		400	I<This callback MUST NOT stop or destroy this or any other periodic
		401	watcher, ever>. If you need to stop it, return 1e30 and stop it
		402	afterwards.
		403
		404	It must return the next time to trigger, based on the passed time value
		405	(that is, the lowest time value larger than to the second argument). It
		406	will usually be called just before the callback will be triggered, but
		407	might be called at other times, too.
		408
		409	This can be used to create very complex timers, such as a timer that
		410	triggers on each midnight, local time (actually 24 hours after the last
		411	midnight, to keep the example simple. If you know a way to do it correctly
		412	in about the same space (without requiring elaborate modules), drop me a
		413	note :):
		414
		415	my $daily = EV::periodic 0, 0, sub {
		416	my ($w, $now) = @_;
		417
		418	use Time::Local ();
		419	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		420	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		421	}, sub {
		422	print "it's midnight or likely shortly after, now\n";
		423	};
		424
		425	=back
		426
214	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	427	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
215		428
		429	=item $w->set ($at, $interval, $reschedule_cb)
		430
		431	Reconfigures the watcher, see the constructor above for details. Can be at
		432	any time.
		433
		434	=item $w->again
		435
		436	Simply stops and starts the watcher again.
		437
		438
216	=item my $w = EV::signal $signal, $callback	439	=item $w = EV::signal $signal, $callback
217		440
218	=item my $w = EV::signal_ns $signal, $callback	441	=item $w = EV::signal_ns $signal, $callback
219		442
220	Call the callback when $signal is received (the signal can be specified	443	Call the callback when $signal is received (the signal can be specified
221	by number or by name, just as with kill or %SIG). Signal watchers are	444	by number or by name, just as with kill or %SIG).
222	persistent no natter what.
223		445
224	EV will grab the signal for the process (the kernel only allows one	446	EV will grab the signal for the process (the kernel only allows one
225	component to receive signals) when you start a signal watcher, and	447	component to receive a signal at a time) when you start a signal watcher,
226	removes it again when you stop it. Pelr does the same when you add/remove	448	and removes it again when you stop it. Perl does the same when you
227	callbacks to %SIG, so watch out.	449	add/remove callbacks to %SIG, so watch out.
228		450
229	Unfortunately, only one handler can be registered per signal. Screw	451	You can have as many signal watchers per signal as you want.
230	libevent.
231		452
232	The C<signal_ns> variant doesn't add/start the newly created watcher.	453	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		454
		455	=item $w->set ($signal)
		456
		457	Reconfigures the watcher, see the constructor above for details. Can be at
		458	any time.
		459
		460	=item $current_signum = $w->signal
		461
		462	=item $old_signum = $w->signal ($new_signal)
		463
		464	Returns the previously set signal (always as a number not name) and
		465	optionally set a new one.
		466
		467
		468	=item $w = EV::child $pid, $callback
		469
		470	=item $w = EV::child_ns $pid, $callback
		471
		472	Call the callback when a status change for pid C<$pid> (or any pid
		473	if C<$pid> is 0) has been received. More precisely: when the process
		474	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
		475	changed/zombie children and call the callback.
		476
		477	You can access both status and pid by using the C<rstatus> and C<rpid>
		478	methods on the watcher object.
		479
		480	You can have as many pid watchers per pid as you want.
		481
		482	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		483
		484	=item $w->set ($pid)
		485
		486	Reconfigures the watcher, see the constructor above for details. Can be at
		487	any time.
		488
		489	=item $current_pid = $w->pid
		490
		491	=item $old_pid = $w->pid ($new_pid)
		492
		493	Returns the previously set process id and optionally set a new one.
		494
		495	=item $exit_status = $w->rstatus
		496
		497	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		498	in perlfunc).
		499
		500	=item $pid = $w->rpid
		501
		502	Return the pid of the awaited child (useful when you have installed a
		503	watcher for all pids).
		504
		505
		506	=item $w = EV::idle $callback
		507
		508	=item $w = EV::idle_ns $callback
		509
		510	Call the callback when there are no pending io, timer/periodic, signal or
		511	child events, i.e. when the process is idle.
		512
		513	The process will not block as long as any idle watchers are active, and
		514	they will be called repeatedly until stopped.
		515
		516	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		517
		518
		519	=item $w = EV::prepare $callback
		520
		521	=item $w = EV::prepare_ns $callback
		522
		523	Call the callback just before the process would block. You can still
		524	create/modify any watchers at this point.
		525
		526	See the EV::check watcher, below, for explanations and an example.
		527
		528	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		529
		530
		531	=item $w = EV::check $callback
		532
		533	=item $w = EV::check_ns $callback
		534
		535	Call the callback just after the process wakes up again (after it has
		536	gathered events), but before any other callbacks have been invoked.
		537
		538	This is used to integrate other event-based software into the EV
		539	mainloop: You register a prepare callback and in there, you create io and
		540	timer watchers as required by the other software. Here is a real-world
		541	example of integrating Net::SNMP (with some details left out):
		542
		543	our @snmp_watcher;
		544
		545	our $snmp_prepare = EV::prepare sub {
		546	# do nothing unless active
		547	$dispatcher->{_event_queue_h}
		548	or return;
		549
		550	# make the dispatcher handle any outstanding stuff
		551	... not shown
		552
		553	# create an IO watcher for each and every socket
		554	@snmp_watcher = (
		555	(map { EV::io $_, EV::READ, sub { } }
		556	keys %{ $dispatcher->{_descriptors} }),
		557
		558	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		559	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		560	0, sub { },
		561	);
		562	};
		563
		564	The callbacks are irrelevant (and are not even being called), the
		565	only purpose of those watchers is to wake up the process as soon as
		566	one of those events occurs (socket readable, or timer timed out). The
		567	corresponding EV::check watcher will then clean up:
		568
		569	our $snmp_check = EV::check sub {
		570	# destroy all watchers
		571	@snmp_watcher = ();
		572
		573	# make the dispatcher handle any new stuff
		574	... not shown
		575	};
		576
		577	The callbacks of the created watchers will not be called as the watchers
		578	are destroyed before this cna happen (remember EV::check gets called
		579	first).
		580
		581	The C<check_ns> variant doesn't start (activate) the newly created watcher.
233		582
234	=back	583	=back
235		584
236	=head1 THE EV::Event CLASS
237
238	All EV functions creating an event watcher (designated by C<my $w =>
239	above) support the following methods on the returned watcher object:
240
241	=over 4
242
243	=item $w->add ($timeout)
244
245	Stops and (re-)starts the event watcher, setting the optional timeout to
246	the given value, or clearing the timeout if none is given.
247
248	=item $w->start
249
250	Stops and (re-)starts the event watcher without touching the timeout.
251
252	=item $w->del
253
254	=item $w->stop
255
256	Stop the event watcher if it was started.
257
258	=item $current_callback = $w->cb
259
260	=item $old_callback = $w->cb ($new_callback)
261
262	Return the previously set callback and optionally set a new one.
263
264	=item $current_fh = $w->fh
265
266	=item $old_fh = $w->fh ($new_fh)
267
268	Returns the previously set filehandle and optionally set a new one (also
269	clears the EV::SIGNAL flag when setting a filehandle).
270
271	=item $current_signal = $w->signal
272
273	=item $old_signal = $w->signal ($new_signal)
274
275	Returns the previously set signal number and optionally set a new one (also sets
276	the EV::SIGNAL flag when setting a signal).
277
278	=item $current_eventmask = $w->events
279
280	=item $old_eventmask = $w->events ($new_eventmask)
281
282	Returns the previously set event mask and optionally set a new one.
283
284	=item $w->timeout ($after, $repeat)
285
286	Resets the timeout (see C<EV::timer> for details).
287
288	=item $w->timeout_abs ($at, $interval)
289
290	Resets the timeout (see C<EV::timer_abs> for details).
291
292	=item $w->priority_set ($priority)
293
294	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
295
296	=back
297
298	=head1 THREADS	585	=head1 THREADS
299		586
300	Threads are not supported by this in any way. Perl pseudo-threads is evil	587	Threads are not supported by this module in any way. Perl pseudo-threads
301	and must die.	588	is evil stuff and must die. As soon as Perl gains real threads I will work
		589	on thread support for it.
		590
		591	=head1 FORK
		592
		593	Most of the "improved" event delivering mechanisms of modern operating
		594	systems have quite a few problems with fork(2) (to put it bluntly: it is
		595	not supported and usually destructive). Libev makes it possible to work
		596	around this by having a function that recreates the kernel state after
		597	fork in the child.
		598
		599	On non-win32 platforms, this module requires the pthread_atfork
		600	functionality to do this automatically for you. This function is quite
		601	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		602	negligible, because everything the function currently does is set a flag
		603	that is checked only when the event loop gets used the next time, so when
		604	you do fork but not use EV, the overhead is minimal.
		605
		606	On win32, there is no notion of fork so all this doesn't apply, of course.
302		607
303	=cut	608	=cut
304		609
305	our $DIED = sub {	610	our $DIED = sub {
306	warn "EV: error in callback (ignoring): $@";	611	warn "EV: error in callback (ignoring): $@";
307	};	612	};
308		613
309	init;	614	default_loop
310		615	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
311	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
312		616
313	1;	617	1;
314		618
315	=head1 SEE ALSO	619	=head1 SEE ALSO
316		620
317	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	621	L<EV::DNS>.
318	L<EV::AnyEvent>.
319		622
320	=head1 AUTHOR	623	=head1 AUTHOR
321		624
322	Marc Lehmann <schmorp@schmorp.de>	625	Marc Lehmann <schmorp@schmorp.de>
323	http://home.schmorp.de/	626	http://home.schmorp.de/

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Revision 1.51 by root, Sat Nov 24 16:12:37 2007 UTC