[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 1.53 by root, Sat Nov 24 16:57:30 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>). While the documentation
68	yourself with its documentation and source code to be able to use this	54	below is comprehensive, one might also consult the documentation of libev
69	module fully.	55	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
70		56	watcher semantics or some discussion on the available backends, or how to
71	Please note thta this module disables the libevent EPOLL method by	57	force a specific backend with C<LIBEV_FLAGS>.
72	default, see BUGS, below, if you need to enable it.
73		58
74	=cut	59	=cut
75		60
76	package EV;	61	package EV;
77		62
78	use strict;	63	use strict;
79		64
80	BEGIN {	65	BEGIN {
81	our $VERSION = '0.03';	66	our $VERSION = '1.3';
82	use XSLoader;	67	use XSLoader;
83	XSLoader::load "EV", $VERSION;	68	XSLoader::load "EV", $VERSION;
84	}	69	}
85		70
		71	@EV::IO::ISA =
		72	@EV::Timer::ISA =
		73	@EV::Periodic::ISA =
		74	@EV::Signal::ISA =
		75	@EV::Idle::ISA =
		76	@EV::Prepare::ISA =
		77	@EV::Check::ISA =
		78	@EV::Child::ISA = "EV::Watcher";
		79
86	=head1 BASIC INTERFACE	80	=head1 BASIC INTERFACE
87		81
88	=over 4	82	=over 4
89
90	=item $EV::NPRI
91
92	How many priority levels are available.
93		83
94	=item $EV::DIED	84	=item $EV::DIED
95		85
96	Must contain a reference to a function that is called when a callback	86	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	87	throws an exception (with $@ containing thr error). The default prints an
98	informative message and continues.	88	informative message and continues.
99		89
100	If this callback throws an exception it will be silently ignored.	90	If this callback throws an exception it will be silently ignored.
101		91
		92	=item $time = EV::time
		93
		94	Returns the current time in (fractional) seconds since the epoch.
		95
102	=item $time = EV::now	96	=item $time = EV::now
103		97
104	Returns the time in (fractional) seconds since the epoch.	98	Returns the time the last event loop iteration has been started. This
105		99	is the time that (relative) timers are based on, and refering to it is
106	=item $version = EV::version	100	usually faster then calling EV::time.
107		101
108	=item $method = EV::method	102	=item $method = EV::method
109		103
110	Return version string and event polling method used.	104	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		105	or EV::METHOD_EPOLL).
111		106
112	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	107	=item EV::loop [$flags]
113		108
114	=item EV::loopexit $after	109	Begin checking for events and calling callbacks. It returns when a
		110	callback calls EV::unloop.
115		111
116	Exit any active loop or dispatch after C<$after> seconds or immediately if	112	The $flags argument can be one of the following:
117	C<$after> is missing or zero.
118		113
119	=item EV::dispatch	114	0 as above
		115	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		116	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
120		117
121	Same as C<EV::loop 0>.	118	=item EV::unloop [$how]
122		119
123	=item EV::event $callback	120	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		121	innermost call to EV::loop return.
124		122
125	Creates a new event watcher waiting for nothing, calling the given callback.	123	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		124	fast as possible.
126		125
		126	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		127
		128	This function rolls together an I/O and a timer watcher for a single
		129	one-shot event without the need for managing a watcher object.
		130
		131	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		132	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		133	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		134	you do not want to wait for some I/O event, specify C<undef> for
		135	C<$fh_or_undef> and C<0> for C<$events>).
		136
		137	If timeout is C<undef> or negative, then there will be no
		138	timeout. Otherwise a EV::timer with this value will be started.
		139
		140	When an error occurs or either the timeout or I/O watcher triggers, then
		141	the callback will be called with the received event set (in general
		142	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		143	C<EV::WRITE> and C<EV::TIMEOUT>).
		144
		145	EV::once doesn't return anything: the watchers stay active till either
		146	of them triggers, then they will be stopped and freed, and the callback
		147	invoked.
		148
		149	=back
		150
		151	=head2 WATCHER
		152
		153	A watcher is an object that gets created to record your interest in some
		154	event. For instance, if you want to wait for STDIN to become readable, you
		155	would create an EV::io watcher for that:
		156
		157	my $watcher = EV::io *STDIN, EV::READ, sub {
		158	my ($watcher, $revents) = @_;
		159	warn "yeah, STDIN should not be readable without blocking!\n"
		160	};
		161
		162	All watchers can be active (waiting for events) or inactive (paused). Only
		163	active watchers will have their callbacks invoked. All callbacks will be
		164	called with at least two arguments: the watcher and a bitmask of received
		165	events.
		166
		167	Each watcher type has its associated bit in revents, so you can use the
		168	same callback for multiple watchers. The event mask is named after the
		169	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		170	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		171	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		172	uses EV::TIMEOUT).
		173
		174	In the rare case where one wants to create a watcher but not start it at
		175	the same time, each constructor has a variant with a trailing C<_ns> in
		176	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		177
		178	Please note that a watcher will automatically be stopped when the watcher
		179	object is destroyed, so you I<need> to keep the watcher objects returned by
		180	the constructors.
		181
		182	Also, all methods changing some aspect of a watcher (->set, ->priority,
		183	->fh and so on) automatically stop and start it again if it is active,
		184	which means pending events get lost.
		185
		186	=head2 WATCHER TYPES
		187
		188	Now lets move to the existing watcher types and asociated methods.
		189
		190	The following methods are available for all watchers. Then followes a
		191	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
		192	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
		193	any type-specific methods (if any).
		194
		195	=over 4
		196
		197	=item $w->start
		198
		199	Starts a watcher if it isn't active already. Does nothing to an already
		200	active watcher. By default, all watchers start out in the active state
		201	(see the description of the C<_ns> variants if you need stopped watchers).
		202
		203	=item $w->stop
		204
		205	Stop a watcher if it is active. Also clear any pending events (events that
		206	have been received but that didn't yet result in a callback invocation),
		207	regardless of wether the watcher was active or not.
		208
		209	=item $bool = $w->is_active
		210
		211	Returns true if the watcher is active, false otherwise.
		212
		213	=item $current_data = $w->data
		214
		215	=item $old_data = $w->data ($new_data)
		216
		217	Queries a freely usable data scalar on the watcher and optionally changes
		218	it. This is a way to associate custom data with a watcher:
		219
		220	my $w = EV::timer 60, 0, sub {
		221	warn $_[0]->data;
		222	};
		223	$w->data ("print me!");
		224
		225	=item $current_cb = $w->cb
		226
		227	=item $old_cb = $w->cb ($new_cb)
		228
		229	Queries the callback on the watcher and optionally changes it. You can do
		230	this at any time without the watcher restarting.
		231
		232	=item $current_priority = $w->priority
		233
		234	=item $old_priority = $w->priority ($new_priority)
		235
		236	Queries the priority on the watcher and optionally changes it. Pending
		237	watchers with higher priority will be invoked first. The valid range of
		238	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		239	-2). If the priority is outside this range it will automatically be
		240	normalised to the nearest valid priority.
		241
		242	The default priority of any newly-created watcher is 0.
		243
		244	Note that the priority semantics have not yet been fleshed out and are
		245	subject to almost certain change.
		246
		247	=item $w->trigger ($revents)
		248
		249	Call the callback now with the given event mask.
		250
		251	=item $previous_state = $w->keepalive ($bool)
		252
		253	Normally, C<EV::loop> will return when there are no active watchers
		254	(which is a "deadlock" because no progress can be made anymore). This is
		255	convinient because it allows you to start your watchers (and your jobs),
		256	call C<EV::loop> once and when it returns you know that all your jobs are
		257	finished (or they forgot to register some watchers for their task :).
		258
		259	Sometimes, however, this gets in your way, for example when you the module
		260	that calls C<EV::loop> (usually the main program) is not the same module
		261	as a long-living watcher (for example a DNS client module written by
		262	somebody else even). Then you might want any outstanding requests to be
		263	handled, but you would not want to keep C<EV::loop> from returning just
		264	because you happen to have this long-running UDP port watcher.
		265
		266	In this case you can clear the keepalive status, which means that even
		267	though your watcher is active, it won't keep C<EV::loop> from returning.
		268
		269	The initial value for keepalive is true (enabled), and you cna change it
		270	any time.
		271
		272	Example: Register an IO watcher for some UDP socket but do not keep the
		273	event loop from running just because of that watcher.
		274
		275	my $udp_socket = ...
		276	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		277	$udp_watcher->keepalive (0);
		278
127	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	279	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
128		280
129	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	281	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
130		282
131	As long as the returned watcher object is alive, call the C<$callback>	283	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	284	when the events specified in C<$eventmask>.
133	is disabled.
134		285
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:	286	The $eventmask can be one or more of these constants ORed together:
144		287
145	EV::READ wait until read() wouldn't block anymore	288	EV::READ wait until read() wouldn't block anymore
146	EV::WRITE wait until write() wouldn't block anymore	289	EV::WRITE wait until write() wouldn't block anymore
147	EV::PERSIST stay active after a (non-timeout) event occured
148		290
149	The C<io_ns> variant doesn't add/start the newly created watcher.	291	The C<io_ns> variant doesn't start (activate) the newly created watcher.
150		292
151	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	293	=item $w->set ($fileno_or_fh, $eventmask)
152		294
153	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	295	Reconfigures the watcher, see the constructor above for details. Can be
		296	called at any time.
154		297
155	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	298	=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		299
159	If the timeout is zero or undef, no timeout will be set, and a normal	300	=item $old_fh = $w->fh ($new_fh)
160	watcher (with the persist flag set!) will be created.
161		301
162	This has the effect of timing out after the specified period of inactivity	302	Returns the previously set filehandle and optionally set a new one.
163	has happened.
164		303
165	Due to the design of libevent, this is also relatively inefficient, having	304	=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		305
		306	=item $old_eventmask = $w->events ($new_eventmask)
		307
		308	Returns the previously set event mask and optionally set a new one.
		309
		310
169	=item my $w = EV::timer $after, $repeat, $callback	311	=item $w = EV::timer $after, $repeat, $callback
170		312
171	=item my $w = EV::timer_ns $after, $repeat, $callback	313	=item $w = EV::timer_ns $after, $repeat, $callback
172		314
173	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	315	Calls the callback after C<$after> seconds (which may be fractional). If
174	timer will be restarted after the callback returns. This means that the	316	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
175	callback would be called roughly every C<$after> seconds, prolonged by the	317	value as $after) after the callback returns.
176	time the callback takes.
177		318
		319	This means that the callback would be called roughly after C<$after>
		320	seconds, and then every C<$repeat> seconds. The timer does his best not
		321	to drift, but it will not invoke the timer more often then once per event
		322	loop iteration, and might drift in other cases. If that isn't acceptable,
		323	look at EV::periodic, which can provide long-term stable timers.
		324
		325	The timer is based on a monotonic clock, that is, if somebody is sitting
		326	in front of the machine while the timer is running and changes the system
		327	clock, the timer will nevertheless run (roughly) the same time.
		328
178	The C<timer_ns> variant doesn't add/start the newly created watcher.	329	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
179		330
180	=item my $w = EV::timer_abs $at, $interval, $callback	331	=item $w->set ($after, $repeat)
181		332
182	=item my $w = EV::timer_abs_ns $at, $interval, $callback	333	Reconfigures the watcher, see the constructor above for details. Can be at
		334	any time.
183		335
184	Similar to EV::timer, but the time is given as an absolute point in time	336	=item $w->again
185	(C<$at>), plus an optional C<$interval>.
186		337
187	If the C<$interval> is zero, then the callback will be called at the time	338	Similar to the C<start> method, but has special semantics for repeating timers:
188	C<$at> if that is in the future, or as soon as possible if its in the
189	past. It will not automatically repeat.
190		339
191	If the C<$interval> is nonzero, then the watcher will always be scheduled	340	If the timer is active and non-repeating, it will be stopped.
192	to time out at the next C<$at + integer * $interval> time.
193		341
194	This can be used to schedule a callback to run at very regular intervals,	342	If the timer is active and repeating, reset the timeout to occur
195	as long as the processing time is less then the interval (otherwise	343	C<$repeat> seconds after now.
196	obviously events will be skipped).	344
		345	If the timer is inactive and repeating, start it using the repeat value.
		346
		347	Otherwise do nothing.
		348
		349	This behaviour is useful when you have a timeout for some IO
		350	operation. You create a timer object with the same value for C<$after> and
		351	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		352	on the timeout.
		353
		354
		355	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		356
		357	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		358
		359	Similar to EV::timer, but is not based on relative timeouts but on
		360	absolute times. Apart from creating "simple" timers that trigger "at" the
		361	specified time, it can also be used for non-drifting absolute timers and
		362	more complex, cron-like, setups that are not adversely affected by time
		363	jumps (i.e. when the system clock is changed by explicit date -s or other
		364	means such as ntpd). It is also the most complex watcher type in EV.
		365
		366	It has three distinct "modes":
		367
		368	=over 4
		369
		370	=item * absolute timer ($interval = $reschedule_cb = 0)
		371
		372	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		373	will not adjust when a time jump occurs, that is, if it is to be run
		374	at January 1st 2011 then it will run when the system time reaches or
		375	surpasses this time.
		376
		377	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		378
		379	In this mode the watcher will always be scheduled to time out at the
		380	next C<$at + N * $interval> time (for some integer N) and then repeat,
		381	regardless of any time jumps.
		382
		383	This can be used to create timers that do not drift with respect to system
		384	time:
		385
		386	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		387
		388	That doesn't mean there will always be 3600 seconds in between triggers,
		389	but only that the the clalback will be called when the system time shows a
		390	full hour (UTC).
197		391
198	Another way to think about it (for the mathematically inclined) is that	392	Another way to think about it (for the mathematically inclined) is that
199	C<timer_abs> will try to tun the callback at the next possible time where	393	EV::periodic will try to run the callback in this mode at the next
200	C<$time = $at (mod $interval)>, regardless of any time jumps.	394	possible time where C<$time = $at (mod $interval)>, regardless of any time
		395	jumps.
201		396
		397	=item * manual reschedule mode ($reschedule_cb = coderef)
		398
		399	In this mode $interval and $at are both being ignored. Instead, each
		400	time the periodic watcher gets scheduled, the reschedule callback
		401	($reschedule_cb) will be called with the watcher as first, and the current
		402	time as second argument.
		403
		404	I<This callback MUST NOT stop or destroy this or any other periodic
		405	watcher, ever>. If you need to stop it, return 1e30 and stop it
		406	afterwards.
		407
		408	It must return the next time to trigger, based on the passed time value
		409	(that is, the lowest time value larger than to the second argument). It
		410	will usually be called just before the callback will be triggered, but
		411	might be called at other times, too.
		412
		413	This can be used to create very complex timers, such as a timer that
		414	triggers on each midnight, local time (actually 24 hours after the last
		415	midnight, to keep the example simple. If you know a way to do it correctly
		416	in about the same space (without requiring elaborate modules), drop me a
		417	note :):
		418
		419	my $daily = EV::periodic 0, 0, sub {
		420	my ($w, $now) = @_;
		421
		422	use Time::Local ();
		423	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		424	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		425	}, sub {
		426	print "it's midnight or likely shortly after, now\n";
		427	};
		428
		429	=back
		430
202	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	431	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
203		432
		433	=item $w->set ($at, $interval, $reschedule_cb)
		434
		435	Reconfigures the watcher, see the constructor above for details. Can be at
		436	any time.
		437
		438	=item $w->again
		439
		440	Simply stops and starts the watcher again.
		441
		442
204	=item my $w = EV::signal $signal, $callback	443	=item $w = EV::signal $signal, $callback
205		444
206	=item my $w = EV::signal_ns $signal, $callback	445	=item $w = EV::signal_ns $signal, $callback
207		446
208	Call the callback when $signal is received (the signal can be specified	447	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	448	by number or by name, just as with kill or %SIG).
210	persistent no natter what.
211		449
212	EV will grab the signal for the process (the kernel only allows one	450	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	451	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	452	and removes it again when you stop it. Perl does the same when you
215	callbacks to %SIG, so watch out.	453	add/remove callbacks to %SIG, so watch out.
216		454
217	Unfortunately, only one handler can be registered per signal. Screw	455	You can have as many signal watchers per signal as you want.
218	libevent.
219		456
220	The C<signal_ns> variant doesn't add/start the newly created watcher.	457	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		458
		459	=item $w->set ($signal)
		460
		461	Reconfigures the watcher, see the constructor above for details. Can be at
		462	any time.
		463
		464	=item $current_signum = $w->signal
		465
		466	=item $old_signum = $w->signal ($new_signal)
		467
		468	Returns the previously set signal (always as a number not name) and
		469	optionally set a new one.
		470
		471
		472	=item $w = EV::child $pid, $callback
		473
		474	=item $w = EV::child_ns $pid, $callback
		475
		476	Call the callback when a status change for pid C<$pid> (or any pid
		477	if C<$pid> is 0) has been received. More precisely: when the process
		478	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
		479	changed/zombie children and call the callback.
		480
		481	You can access both status and pid by using the C<rstatus> and C<rpid>
		482	methods on the watcher object.
		483
		484	You can have as many pid watchers per pid as you want.
		485
		486	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		487
		488	=item $w->set ($pid)
		489
		490	Reconfigures the watcher, see the constructor above for details. Can be at
		491	any time.
		492
		493	=item $current_pid = $w->pid
		494
		495	=item $old_pid = $w->pid ($new_pid)
		496
		497	Returns the previously set process id and optionally set a new one.
		498
		499	=item $exit_status = $w->rstatus
		500
		501	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		502	in perlfunc).
		503
		504	=item $pid = $w->rpid
		505
		506	Return the pid of the awaited child (useful when you have installed a
		507	watcher for all pids).
		508
		509
		510	=item $w = EV::idle $callback
		511
		512	=item $w = EV::idle_ns $callback
		513
		514	Call the callback when there are no pending io, timer/periodic, signal or
		515	child events, i.e. when the process is idle.
		516
		517	The process will not block as long as any idle watchers are active, and
		518	they will be called repeatedly until stopped.
		519
		520	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		521
		522
		523	=item $w = EV::prepare $callback
		524
		525	=item $w = EV::prepare_ns $callback
		526
		527	Call the callback just before the process would block. You can still
		528	create/modify any watchers at this point.
		529
		530	See the EV::check watcher, below, for explanations and an example.
		531
		532	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		533
		534
		535	=item $w = EV::check $callback
		536
		537	=item $w = EV::check_ns $callback
		538
		539	Call the callback just after the process wakes up again (after it has
		540	gathered events), but before any other callbacks have been invoked.
		541
		542	This is used to integrate other event-based software into the EV
		543	mainloop: You register a prepare callback and in there, you create io and
		544	timer watchers as required by the other software. Here is a real-world
		545	example of integrating Net::SNMP (with some details left out):
		546
		547	our @snmp_watcher;
		548
		549	our $snmp_prepare = EV::prepare sub {
		550	# do nothing unless active
		551	$dispatcher->{_event_queue_h}
		552	or return;
		553
		554	# make the dispatcher handle any outstanding stuff
		555	... not shown
		556
		557	# create an IO watcher for each and every socket
		558	@snmp_watcher = (
		559	(map { EV::io $_, EV::READ, sub { } }
		560	keys %{ $dispatcher->{_descriptors} }),
		561
		562	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		563	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		564	0, sub { },
		565	);
		566	};
		567
		568	The callbacks are irrelevant (and are not even being called), the
		569	only purpose of those watchers is to wake up the process as soon as
		570	one of those events occurs (socket readable, or timer timed out). The
		571	corresponding EV::check watcher will then clean up:
		572
		573	our $snmp_check = EV::check sub {
		574	# destroy all watchers
		575	@snmp_watcher = ();
		576
		577	# make the dispatcher handle any new stuff
		578	... not shown
		579	};
		580
		581	The callbacks of the created watchers will not be called as the watchers
		582	are destroyed before this cna happen (remember EV::check gets called
		583	first).
		584
		585	The C<check_ns> variant doesn't start (activate) the newly created watcher.
221		586
222	=back	587	=back
223		588
224	=head1 THE EV::Event CLASS	589	=head1 THREADS
225		590
226	All EV functions creating an event watcher (designated by C<my $w =>	591	Threads are not supported by this module in any way. Perl pseudo-threads
227	above) support the following methods on the returned watcher object:	592	is evil stuff and must die. As soon as Perl gains real threads I will work
		593	on thread support for it.
228		594
229	=over 4	595	=head1 FORK
230		596
231	=item $w->add ($timeout)	597	Most of the "improved" event delivering mechanisms of modern operating
		598	systems have quite a few problems with fork(2) (to put it bluntly: it is
		599	not supported and usually destructive). Libev makes it possible to work
		600	around this by having a function that recreates the kernel state after
		601	fork in the child.
232		602
233	Stops and (re-)starts the event watcher, setting the optional timeout to	603	On non-win32 platforms, this module requires the pthread_atfork
234	the given value, or clearing the timeout if none is given.	604	functionality to do this automatically for you. This function is quite
		605	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		606	negligible, because everything the function currently does is set a flag
		607	that is checked only when the event loop gets used the next time, so when
		608	you do fork but not use EV, the overhead is minimal.
235		609
236	=item $w->start	610	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		611
299	=cut	612	=cut
300		613
301	our $DIED = sub {	614	our $DIED = sub {
302	warn "EV: error in callback (ignoring): $@";	615	warn "EV: error in callback (ignoring): $@";
303	};	616	};
304		617
305	our $NPRI = 4;	618	default_loop
306	our $BASE = init;	619	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
307	priority_init $NPRI;
308
309	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
310		620
311	1;	621	1;
312		622
313	=head1 SEE ALSO	623	=head1 SEE ALSO
314		624
315	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	625	L<EV::DNS>.
316	L<EV::AnyEvent>.
317		626
318	=head1 AUTHOR	627	=head1 AUTHOR
319		628
320	Marc Lehmann <schmorp@schmorp.de>	629	Marc Lehmann <schmorp@schmorp.de>
321	http://home.schmorp.de/	630	http://home.schmorp.de/

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Revision 1.12 by root, Mon Oct 29 08:52:28 2007 UTC vs.
Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC