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

Comparing EV/EV.pm (file contents):
Revision 1.12 by root, Mon Oct 29 08:52:28 2007 UTC vs.
Revision 1.50 by root, Sat Nov 24 08:42:38 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, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & 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, $events) = @_;
39	if ($_[1] & 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		44
58	# MAINLOOP	45	# MAINLOOP
59	EV::dispatch; # loop as long as watchers are active	46	EV::loop; # loop until EV::unloop is called or all watchers stop
60	EV::loop; # the same thing
61	EV::loop EV::LOOP_ONCE; # block until some events could be handles	47	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
62	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
63		49
64	=head1 DESCRIPTION	50	=head1 DESCRIPTION
65		51
66	This module provides an interface to libevent	52	This module provides an interface to libev
67	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	53	(L<http://software.schmorp.de/pkg/libev.html>).
68	yourself with its documentation and source code to be able to use this
69	module fully.
70
71	Please note thta this module disables the libevent EPOLL method by
72	default, see BUGS, below, if you need to enable it.
73		54
74	=cut	55	=cut
75		56
76	package EV;	57	package EV;
77		58
78	use strict;	59	use strict;
79		60
80	BEGIN {	61	BEGIN {
81	our $VERSION = '0.03';	62	our $VERSION = '1.2';
82	use XSLoader;	63	use XSLoader;
83	XSLoader::load "EV", $VERSION;	64	XSLoader::load "EV", $VERSION;
84	}	65	}
85		66
		67	@EV::IO::ISA =
		68	@EV::Timer::ISA =
		69	@EV::Periodic::ISA =
		70	@EV::Signal::ISA =
		71	@EV::Idle::ISA =
		72	@EV::Prepare::ISA =
		73	@EV::Check::ISA =
		74	@EV::Child::ISA = "EV::Watcher";
		75
86	=head1 BASIC INTERFACE	76	=head1 BASIC INTERFACE
87		77
88	=over 4	78	=over 4
89
90	=item $EV::NPRI
91
92	How many priority levels are available.
93		79
94	=item $EV::DIED	80	=item $EV::DIED
95		81
96	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
97	throws an exception (with $@ containing thr error). The default prints an	83	throws an exception (with $@ containing thr error). The default prints an
98	informative message and continues.	84	informative message and continues.
99		85
100	If this callback throws an exception it will be silently ignored.	86	If this callback throws an exception it will be silently ignored.
101		87
		88	=item $time = EV::time
		89
		90	Returns the current time in (fractional) seconds since the epoch.
		91
102	=item $time = EV::now	92	=item $time = EV::now
103		93
104	Returns the time in (fractional) seconds since the epoch.	94	Returns the time the last event loop iteration has been started. This
105		95	is the time that (relative) timers are based on, and refering to it is
106	=item $version = EV::version	96	usually faster then calling EV::time.
107		97
108	=item $method = EV::method	98	=item $method = EV::method
109		99
110	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).
111		102
112	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	103	=item EV::loop [$flags]
113		104
114	=item EV::loopexit $after	105	Begin checking for events and calling callbacks. It returns when a
		106	callback calls EV::unloop.
115		107
116	Exit any active loop or dispatch after C<$after> seconds or immediately if	108	The $flags argument can be one of the following:
117	C<$after> is missing or zero.
118		109
119	=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)
120		113
121	Same as C<EV::loop 0>.	114	=item EV::unloop [$how]
122		115
123	=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.
124		118
125	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.
126		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
127	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	275	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
128		276
129	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	277	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
130		278
131	As long as the returned watcher object is alive, call the C<$callback>	279	As long as the returned watcher object is alive, call the C<$callback>
132	when the events specified in C<$eventmask> happen. Initially, the timeout	280	when the events specified in C<$eventmask>.
133	is disabled.
134		281
135	You can additionall set a timeout to occur on the watcher, but note that
136	this timeout will not be reset when you get an I/O event in the EV::PERSIST
137	case, and reaching a timeout will always stop the watcher even in the
138	EV::PERSIST case.
139
140	If you want a timeout to occur only after a specific time of inactivity, set
141	a repeating timeout and do NOT use EV::PERSIST.
142
143	Eventmask can be one or more of these constants ORed together:	282	The $eventmask can be one or more of these constants ORed together:
144		283
145	EV::READ wait until read() wouldn't block anymore	284	EV::READ wait until read() wouldn't block anymore
146	EV::WRITE wait until write() wouldn't block anymore	285	EV::WRITE wait until write() wouldn't block anymore
147	EV::PERSIST stay active after a (non-timeout) event occured
148		286
149	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.
150		288
151	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	289	=item $w->set ($fileno_or_fh, $eventmask)
152		290
153	=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.
154		293
155	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	294	=item $current_fh = $w->fh
156	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
157	and will automatically be cleared. The watcher will be restarted after each event.
158		295
159	If the timeout is zero or undef, no timeout will be set, and a normal	296	=item $old_fh = $w->fh ($new_fh)
160	watcher (with the persist flag set!) will be created.
161		297
162	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.
163	has happened.
164		299
165	Due to the design of libevent, this is also relatively inefficient, having	300	=item $current_eventmask = $w->events
166	one or two io watchers and a separate timeout watcher that you reset on
167	activity (by calling its C<start> method) is usually more efficient.
168		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
169	=item my $w = EV::timer $after, $repeat, $callback	307	=item $w = EV::timer $after, $repeat, $callback
170		308
171	=item my $w = EV::timer_ns $after, $repeat, $callback	309	=item $w = EV::timer_ns $after, $repeat, $callback
172		310
173	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	311	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,
174	timer will be restarted after the callback returns. This means that the	312	the timer will be restarted (with the $repeat value as $after) after the
175	callback would be called roughly every C<$after> seconds, prolonged by the	313	callback returns.
176	time the callback takes.
177		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
178	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.
179		326
180	=item my $w = EV::timer_abs $at, $interval, $callback	327	=item $w->set ($after, $repeat)
181		328
182	=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.
183		331
184	Similar to EV::timer, but the time is given as an absolute point in time	332	=item $w->again
185	(C<$at>), plus an optional C<$interval>.
186		333
187	If the C<$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:
188	C<$at> if that is in the future, or as soon as possible if its in the
189	past. It will not automatically repeat.
190		335
191	If the C<$interval> is nonzero, then the watcher will always be scheduled	336	If the timer is active and non-repeating, it will be stopped.
192	to time out at the next C<$at + integer * $interval> time.
193		337
194	This can be used to schedule a callback to run at very regular intervals,	338	If the timer is active and repeating, reset the timeout to occur
195	as long as the processing time is less then the interval (otherwise	339	C<$repeat> seconds after now.
196	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 $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		383
		384	That doesn't mean there will always be 3600 seconds in between triggers,
		385	but only that the the clalback will be called when the system time shows a
		386	full hour (UTC).
197		387
198	Another way to think about it (for the mathematically inclined) is that	388	Another way to think about it (for the mathematically inclined) is that
199	C<timer_abs> will try to tun the callback at the next possible time where	389	EV::periodic will try to run the callback in this mode at the next
200	C<$time = $at (mod $interval)>, regardless of any time jumps.	390	possible time where C<$time = $at (mod $interval)>, regardless of any time
		391	jumps.
201		392
		393	=item * manual reschedule mode ($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
202	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.
203		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
204	=item my $w = EV::signal $signal, $callback	439	=item $w = EV::signal $signal, $callback
205		440
206	=item my $w = EV::signal_ns $signal, $callback	441	=item $w = EV::signal_ns $signal, $callback
207		442
208	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
209	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).
210	persistent no natter what.
211		445
212	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
213	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,
214	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
215	callbacks to %SIG, so watch out.	449	add/remove callbacks to %SIG, so watch out.
216		450
217	Unfortunately, only one handler can be registered per signal. Screw	451	You can have as many signal watchers per signal as you want.
218	libevent.
219		452
220	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.
221		582
222	=back	583	=back
223		584
224	=head1 THE EV::Event CLASS	585	=head1 THREADS
225		586
226	All EV functions creating an event watcher (designated by C<my $w =>	587	Threads are not supported by this module in any way. Perl pseudo-threads
227	above) support the following methods on the returned watcher object:	588	is evil stuff and must die. As soon as Perl gains real threads I will work
		589	on thread support for it.
228		590
229	=over 4	591	=head1 FORK
230		592
231	=item $w->add ($timeout)	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.
232		598
233	Stops and (re-)starts the event watcher, setting the optional timeout to	599	On non-win32 platforms, this module requires the pthread_atfork
234	the given value, or clearing the timeout if none is given.	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.
235		605
236	=item $w->start	606	On win32, there is no notion of fork so all this doesn't apply, of course.
237
238	Stops and (re-)starts the event watcher without touching the timeout.
239
240	=item $w->del
241
242	=item $w->stop
243
244	Stop the event watcher if it was started.
245
246	=item $current_callback = $w->cb
247
248	=item $old_callback = $w->cb ($new_callback)
249
250	Return the previously set callback and optionally set a new one.
251
252	=item $current_fh = $w->fh
253
254	=item $old_fh = $w->fh ($new_fh)
255
256	Returns the previously set filehandle and optionally set a new one (also
257	clears the EV::SIGNAL flag when setting a filehandle).
258
259	=item $current_signal = $w->signal
260
261	=item $old_signal = $w->signal ($new_signal)
262
263	Returns the previously set signal number and optionally set a new one (also sets
264	the EV::SIGNAL flag when setting a signal).
265
266	=item $current_eventmask = $w->events
267
268	=item $old_eventmask = $w->events ($new_eventmask)
269
270	Returns the previously set event mask and optionally set a new one.
271
272	=item $w->timeout ($after, $repeat)
273
274	Resets the timeout (see C<EV::timer> for details).
275
276	=item $w->timeout_abs ($at, $interval)
277
278	Resets the timeout (see C<EV::timer_abs> for details).
279
280	=item $w->priority_set ($priority)
281
282	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
283
284	=back
285
286	=head1 BUGS
287
288	Lots. Libevent itself isn't well tested and rather buggy, and this module
289	is quite new at the moment.
290
291	Please note that the epoll method is not, in general, reliable in programs
292	that use fork (even if no libveent calls are being made in the forked
293	process). If your program behaves erratically, try setting the environment
294	variable C<EVENT_NOEPOLL> first when running the program.
295
296	In general, if you fork, then you can only use the EV module in one of the
297	children.
298		607
299	=cut	608	=cut
300		609
301	our $DIED = sub {	610	our $DIED = sub {
302	warn "EV: error in callback (ignoring): $@";	611	warn "EV: error in callback (ignoring): $@";
303	};	612	};
304		613
305	our $NPRI = 4;	614	default_loop
306	our $BASE = init;	615	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
307	priority_init $NPRI;
308
309	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
310		616
311	1;	617	1;
312		618
313	=head1 SEE ALSO	619	=head1 SEE ALSO
314		620
315	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	621	L<EV::DNS>.
316	L<EV::AnyEvent>.
317		622
318	=head1 AUTHOR	623	=head1 AUTHOR
319		624
320	Marc Lehmann <schmorp@schmorp.de>	625	Marc Lehmann <schmorp@schmorp.de>
321	http://home.schmorp.de/	626	http://home.schmorp.de/

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Revision 1.12 by root, Mon Oct 29 08:52:28 2007 UTC vs.
Revision 1.50 by root, Sat Nov 24 08:42:38 2007 UTC