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

Comparing EV/EV.pm (file contents):
Revision 1.17 by root, Wed Oct 31 21:34:45 2007 UTC vs.
Revision 1.55 by root, Tue Nov 27 08:11:52 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		44
58	# CHILD/PID STATUS CHANGES	45	# STAT CHANGES
59		46	my $w = EV::stat "/etc/passwd", 10, sub {
60	my $w = EV::child 666, sub {
61	my ($w, $revents, $status) = @_;	47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
62	};	49	};
63		50
64	# MAINLOOP	51	# MAINLOOP
65	EV::dispatch; # loop as long as watchers are active	52	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	53	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	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
69		55
70	=head1 DESCRIPTION	56	=head1 DESCRIPTION
71		57
72	This module provides an interface to libev	58	This module provides an interface to libev
73	(L<http://software.schmorp.de/pkg/libev.html>). You probably should	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
74	acquaint yourself with its documentation and source code to be able to use	60	below is comprehensive, one might also consult the documentation of libev
75	this module fully.	61	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
		62	watcher semantics or some discussion on the available backends, or how to
		63	force a specific backend with C<LIBEV_FLAGS>.
76		64
77	=cut	65	=cut
78		66
79	package EV;	67	package EV;
80		68
81	use strict;	69	use strict;
82		70
83	BEGIN {	71	BEGIN {
84	our $VERSION = '0.03';	72	our $VERSION = '1.4';
85	use XSLoader;	73	use XSLoader;
86	XSLoader::load "EV", $VERSION;	74	XSLoader::load "EV", $VERSION;
87	}	75	}
88		76
		77	@EV::IO::ISA =
		78	@EV::Timer::ISA =
		79	@EV::Periodic::ISA =
		80	@EV::Signal::ISA =
		81	@EV::Idle::ISA =
		82	@EV::Prepare::ISA =
		83	@EV::Check::ISA =
		84	@EV::Child::ISA =
		85	@EV::Embed::ISA =
89	@EV::Io::ISA = "EV::Watcher";	86	@EV::Stat::ISA = "EV::Watcher";
90	@EV::Time::ISA = "EV::Watcher";
91	@EV::Timer::ISA = "EV::Time";
92	@EV::Periodic::ISA = "EV::Time";
93	@EV::Signal::ISA = "EV::Watcher";
94	@EV::Idle::ISA = "EV::Watcher";
95	@EV::Prepare::ISA = "EV::Watcher";
96	@EV::Check::ISA = "EV::Watcher";
97	@EV::Child::ISA = "EV::Watcher";
98		87
99	=head1 BASIC INTERFACE	88	=head1 BASIC INTERFACE
100		89
101	=over 4	90	=over 4
102
103	=item $EV::NPRI
104
105	How many priority levels are available.
106		91
107	=item $EV::DIED	92	=item $EV::DIED
108		93
109	Must contain a reference to a function that is called when a callback	94	Must contain a reference to a function that is called when a callback
110	throws an exception (with $@ containing thr error). The default prints an	95	throws an exception (with $@ containing thr error). The default prints an
111	informative message and continues.	96	informative message and continues.
112		97
113	If this callback throws an exception it will be silently ignored.	98	If this callback throws an exception it will be silently ignored.
114		99
		100	=item $time = EV::time
		101
		102	Returns the current time in (fractional) seconds since the epoch.
		103
115	=item $time = EV::now	104	=item $time = EV::now
116		105
117	Returns the time in (fractional) seconds since the epoch.	106	Returns the time the last event loop iteration has been started. This
118		107	is the time that (relative) timers are based on, and refering to it is
119	=item $version = EV::version	108	usually faster then calling EV::time.
120		109
121	=item $method = EV::method	110	=item $method = EV::method
122		111
123	Return version string and event polling method used.	112	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		113	or EV::METHOD_EPOLL).
124		114
125	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	115	=item EV::loop [$flags]
126		116
127	=item EV::loopexit $after	117	Begin checking for events and calling callbacks. It returns when a
		118	callback calls EV::unloop.
128		119
129	Exit any active loop or dispatch after C<$after> seconds or immediately if	120	The $flags argument can be one of the following:
130	C<$after> is missing or zero.
131		121
132	=item EV::dispatch	122	0 as above
		123	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		124	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
133		125
134	Same as C<EV::loop 0>.	126	=item EV::unloop [$how]
135		127
136	=item EV::event $callback	128	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		129	innermost call to EV::loop return.
137		130
138	Creates a new event watcher waiting for nothing, calling the given callback.	131	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		132	fast as possible.
139		133
		134	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		135
		136	This function rolls together an I/O and a timer watcher for a single
		137	one-shot event without the need for managing a watcher object.
		138
		139	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		140	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		141	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		142	you do not want to wait for some I/O event, specify C<undef> for
		143	C<$fh_or_undef> and C<0> for C<$events>).
		144
		145	If timeout is C<undef> or negative, then there will be no
		146	timeout. Otherwise a EV::timer with this value will be started.
		147
		148	When an error occurs or either the timeout or I/O watcher triggers, then
		149	the callback will be called with the received event set (in general
		150	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		151	C<EV::WRITE> and C<EV::TIMEOUT>).
		152
		153	EV::once doesn't return anything: the watchers stay active till either
		154	of them triggers, then they will be stopped and freed, and the callback
		155	invoked.
		156
		157	=back
		158
		159	=head2 WATCHER OBJECTS
		160
		161	A watcher is an object that gets created to record your interest in some
		162	event. For instance, if you want to wait for STDIN to become readable, you
		163	would create an EV::io watcher for that:
		164
		165	my $watcher = EV::io *STDIN, EV::READ, sub {
		166	my ($watcher, $revents) = @_;
		167	warn "yeah, STDIN should not be readable without blocking!\n"
		168	};
		169
		170	All watchers can be active (waiting for events) or inactive (paused). Only
		171	active watchers will have their callbacks invoked. All callbacks will be
		172	called with at least two arguments: the watcher and a bitmask of received
		173	events.
		174
		175	Each watcher type has its associated bit in revents, so you can use the
		176	same callback for multiple watchers. The event mask is named after the
		177	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		178	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		179	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		180	uses EV::TIMEOUT).
		181
		182	In the rare case where one wants to create a watcher but not start it at
		183	the same time, each constructor has a variant with a trailing C<_ns> in
		184	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		185
		186	Please note that a watcher will automatically be stopped when the watcher
		187	object is destroyed, so you I<need> to keep the watcher objects returned by
		188	the constructors.
		189
		190	Also, all methods changing some aspect of a watcher (->set, ->priority,
		191	->fh and so on) automatically stop and start it again if it is active,
		192	which means pending events get lost.
		193
		194	=head2 COMMON WATCHER METHODS
		195
		196	This section lists methods common to all watchers.
		197
		198	=over 4
		199
		200	=item $w->start
		201
		202	Starts a watcher if it isn't active already. Does nothing to an already
		203	active watcher. By default, all watchers start out in the active state
		204	(see the description of the C<_ns> variants if you need stopped watchers).
		205
		206	=item $w->stop
		207
		208	Stop a watcher if it is active. Also clear any pending events (events that
		209	have been received but that didn't yet result in a callback invocation),
		210	regardless of wether the watcher was active or not.
		211
		212	=item $bool = $w->is_active
		213
		214	Returns true if the watcher is active, false otherwise.
		215
		216	=item $current_data = $w->data
		217
		218	=item $old_data = $w->data ($new_data)
		219
		220	Queries a freely usable data scalar on the watcher and optionally changes
		221	it. This is a way to associate custom data with a watcher:
		222
		223	my $w = EV::timer 60, 0, sub {
		224	warn $_[0]->data;
		225	};
		226	$w->data ("print me!");
		227
		228	=item $current_cb = $w->cb
		229
		230	=item $old_cb = $w->cb ($new_cb)
		231
		232	Queries the callback on the watcher and optionally changes it. You can do
		233	this at any time without the watcher restarting.
		234
		235	=item $current_priority = $w->priority
		236
		237	=item $old_priority = $w->priority ($new_priority)
		238
		239	Queries the priority on the watcher and optionally changes it. Pending
		240	watchers with higher priority will be invoked first. The valid range of
		241	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		242	-2). If the priority is outside this range it will automatically be
		243	normalised to the nearest valid priority.
		244
		245	The default priority of any newly-created watcher is 0.
		246
		247	Note that the priority semantics have not yet been fleshed out and are
		248	subject to almost certain change.
		249
		250	=item $w->trigger ($revents)
		251
		252	Call the callback now with the given event mask.
		253
		254	=item $previous_state = $w->keepalive ($bool)
		255
		256	Normally, C<EV::loop> will return when there are no active watchers
		257	(which is a "deadlock" because no progress can be made anymore). This is
		258	convinient because it allows you to start your watchers (and your jobs),
		259	call C<EV::loop> once and when it returns you know that all your jobs are
		260	finished (or they forgot to register some watchers for their task :).
		261
		262	Sometimes, however, this gets in your way, for example when you the module
		263	that calls C<EV::loop> (usually the main program) is not the same module
		264	as a long-living watcher (for example a DNS client module written by
		265	somebody else even). Then you might want any outstanding requests to be
		266	handled, but you would not want to keep C<EV::loop> from returning just
		267	because you happen to have this long-running UDP port watcher.
		268
		269	In this case you can clear the keepalive status, which means that even
		270	though your watcher is active, it won't keep C<EV::loop> from returning.
		271
		272	The initial value for keepalive is true (enabled), and you cna change it
		273	any time.
		274
		275	Example: Register an IO watcher for some UDP socket but do not keep the
		276	event loop from running just because of that watcher.
		277
		278	my $udp_socket = ...
		279	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		280	$udp_watcher->keepalive (0);
		281
		282	=back
		283
		284
		285	=head2 WATCHER TYPES
		286
		287	Each of the following subsections describes a single watcher type.
		288
		289	=head3 IO WATCHERS - is this file descriptor readable or writable?
		290
		291	=over 4
		292
140	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	293	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
141		294
142	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	295	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
143		296
144	As long as the returned watcher object is alive, call the C<$callback>	297	As long as the returned watcher object is alive, call the C<$callback>
145	when the events specified in C<$eventmask> happen. Initially, the timeout	298	when at least one of events specified in C<$eventmask> occurs.
146	is disabled.
147		299
148	You can additionall set a timeout to occur on the watcher, but note that
149	this timeout will not be reset when you get an I/O event in the EV::PERSIST
150	case, and reaching a timeout will always stop the watcher even in the
151	EV::PERSIST case.
152
153	If you want a timeout to occur only after a specific time of inactivity, set
154	a repeating timeout and do NOT use EV::PERSIST.
155
156	Eventmask can be one or more of these constants ORed together:	300	The $eventmask can be one or more of these constants ORed together:
157		301
158	EV::READ wait until read() wouldn't block anymore	302	EV::READ wait until read() wouldn't block anymore
159	EV::WRITE wait until write() wouldn't block anymore	303	EV::WRITE wait until write() wouldn't block anymore
160	EV::PERSIST stay active after a (non-timeout) event occured
161		304
162	The C<io_ns> variant doesn't add/start the newly created watcher.	305	The C<io_ns> variant doesn't start (activate) the newly created watcher.
163		306
164	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	307	=item $w->set ($fileno_or_fh, $eventmask)
165		308
166	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	309	Reconfigures the watcher, see the constructor above for details. Can be
		310	called at any time.
167		311
168	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	312	=item $current_fh = $w->fh
169	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
170	and will automatically be cleared. The watcher will be restarted after each event.
171		313
172	If the timeout is zero or undef, no timeout will be set, and a normal	314	=item $old_fh = $w->fh ($new_fh)
173	watcher (with the persist flag set!) will be created.
174		315
175	This has the effect of timing out after the specified period of inactivity	316	Returns the previously set filehandle and optionally set a new one.
176	has happened.
177		317
178	Due to the design of libevent, this is also relatively inefficient, having	318	=item $current_eventmask = $w->events
179	one or two io watchers and a separate timeout watcher that you reset on
180	activity (by calling its C<start> method) is usually more efficient.
181		319
		320	=item $old_eventmask = $w->events ($new_eventmask)
		321
		322	Returns the previously set event mask and optionally set a new one.
		323
		324	=back
		325
		326
		327	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		328
		329	=over 4
		330
182	=item my $w = EV::timer $after, $repeat, $callback	331	=item $w = EV::timer $after, $repeat, $callback
183		332
184	=item my $w = EV::timer_ns $after, $repeat, $callback	333	=item $w = EV::timer_ns $after, $repeat, $callback
185		334
186	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	335	Calls the callback after C<$after> seconds (which may be fractional). If
187	timer will be restarted after the callback returns. This means that the	336	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
188	callback would be called roughly every C<$after> seconds, prolonged by the	337	value as $after) after the callback returns.
189	time the callback takes.
190		338
		339	This means that the callback would be called roughly after C<$after>
		340	seconds, and then every C<$repeat> seconds. The timer does his best not
		341	to drift, but it will not invoke the timer more often then once per event
		342	loop iteration, and might drift in other cases. If that isn't acceptable,
		343	look at EV::periodic, which can provide long-term stable timers.
		344
		345	The timer is based on a monotonic clock, that is, if somebody is sitting
		346	in front of the machine while the timer is running and changes the system
		347	clock, the timer will nevertheless run (roughly) the same time.
		348
191	The C<timer_ns> variant doesn't add/start the newly created watcher.	349	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
192		350
193	=item my $w = EV::timer_abs $at, $interval, $callback	351	=item $w->set ($after, $repeat)
194		352
195	=item my $w = EV::timer_abs_ns $at, $interval, $callback	353	Reconfigures the watcher, see the constructor above for details. Can be called at
		354	any time.
196		355
197	Similar to EV::timer, but the time is given as an absolute point in time	356	=item $w->again
198	(C<$at>), plus an optional C<$interval>.
199		357
200	If the C<$interval> is zero, then the callback will be called at the time	358	Similar to the C<start> method, but has special semantics for repeating timers:
201	C<$at> if that is in the future, or as soon as possible if its in the
202	past. It will not automatically repeat.
203		359
204	If the C<$interval> is nonzero, then the watcher will always be scheduled	360	If the timer is active and non-repeating, it will be stopped.
205	to time out at the next C<$at + integer * $interval> time.
206		361
207	This can be used to schedule a callback to run at very regular intervals,	362	If the timer is active and repeating, reset the timeout to occur
208	as long as the processing time is less then the interval (otherwise	363	C<$repeat> seconds after now.
209	obviously events will be skipped).	364
		365	If the timer is inactive and repeating, start it using the repeat value.
		366
		367	Otherwise do nothing.
		368
		369	This behaviour is useful when you have a timeout for some IO
		370	operation. You create a timer object with the same value for C<$after> and
		371	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		372	on the timeout.
		373
		374	=back
		375
		376
		377	=head3 PERIODIC WATCHERS - to cron or not to cron?
		378
		379	=over 4
		380
		381	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		382
		383	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		384
		385	Similar to EV::timer, but is not based on relative timeouts but on
		386	absolute times. Apart from creating "simple" timers that trigger "at" the
		387	specified time, it can also be used for non-drifting absolute timers and
		388	more complex, cron-like, setups that are not adversely affected by time
		389	jumps (i.e. when the system clock is changed by explicit date -s or other
		390	means such as ntpd). It is also the most complex watcher type in EV.
		391
		392	It has three distinct "modes":
		393
		394	=over 4
		395
		396	=item * absolute timer ($interval = $reschedule_cb = 0)
		397
		398	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		399	will not adjust when a time jump occurs, that is, if it is to be run
		400	at January 1st 2011 then it will run when the system time reaches or
		401	surpasses this time.
		402
		403	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		404
		405	In this mode the watcher will always be scheduled to time out at the
		406	next C<$at + N * $interval> time (for some integer N) and then repeat,
		407	regardless of any time jumps.
		408
		409	This can be used to create timers that do not drift with respect to system
		410	time:
		411
		412	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		413
		414	That doesn't mean there will always be 3600 seconds in between triggers,
		415	but only that the the clalback will be called when the system time shows a
		416	full hour (UTC).
210		417
211	Another way to think about it (for the mathematically inclined) is that	418	Another way to think about it (for the mathematically inclined) is that
212	C<timer_abs> will try to tun the callback at the next possible time where	419	EV::periodic will try to run the callback in this mode at the next
213	C<$time = $at (mod $interval)>, regardless of any time jumps.	420	possible time where C<$time = $at (mod $interval)>, regardless of any time
		421	jumps.
214		422
		423	=item * manual reschedule mode ($reschedule_cb = coderef)
		424
		425	In this mode $interval and $at are both being ignored. Instead, each
		426	time the periodic watcher gets scheduled, the reschedule callback
		427	($reschedule_cb) will be called with the watcher as first, and the current
		428	time as second argument.
		429
		430	I<This callback MUST NOT stop or destroy this or any other periodic
		431	watcher, ever>. If you need to stop it, return 1e30 and stop it
		432	afterwards.
		433
		434	It must return the next time to trigger, based on the passed time value
		435	(that is, the lowest time value larger than to the second argument). It
		436	will usually be called just before the callback will be triggered, but
		437	might be called at other times, too.
		438
		439	This can be used to create very complex timers, such as a timer that
		440	triggers on each midnight, local time (actually 24 hours after the last
		441	midnight, to keep the example simple. If you know a way to do it correctly
		442	in about the same space (without requiring elaborate modules), drop me a
		443	note :):
		444
		445	my $daily = EV::periodic 0, 0, sub {
		446	my ($w, $now) = @_;
		447
		448	use Time::Local ();
		449	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		450	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		451	}, sub {
		452	print "it's midnight or likely shortly after, now\n";
		453	};
		454
		455	=back
		456
215	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	457	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
216		458
		459	=item $w->set ($at, $interval, $reschedule_cb)
		460
		461	Reconfigures the watcher, see the constructor above for details. Can be called at
		462	any time.
		463
		464	=item $w->again
		465
		466	Simply stops and starts the watcher again.
		467
		468	=back
		469
		470
		471	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		472
		473	=over 4
		474
217	=item my $w = EV::signal $signal, $callback	475	=item $w = EV::signal $signal, $callback
218		476
219	=item my $w = EV::signal_ns $signal, $callback	477	=item $w = EV::signal_ns $signal, $callback
220		478
221	Call the callback when $signal is received (the signal can be specified	479	Call the callback when $signal is received (the signal can be specified by
222	by number or by name, just as with kill or %SIG). Signal watchers are	480	number or by name, just as with C<kill> or C<%SIG>).
223	persistent no natter what.
224		481
225	EV will grab the signal for the process (the kernel only allows one	482	EV will grab the signal for the process (the kernel only allows one
226	component to receive signals) when you start a signal watcher, and	483	component to receive a signal at a time) when you start a signal watcher,
227	removes it again when you stop it. Pelr does the same when you add/remove	484	and removes it again when you stop it. Perl does the same when you
228	callbacks to %SIG, so watch out.	485	add/remove callbacks to C<%SIG>, so watch out.
229		486
230	Unfortunately, only one handler can be registered per signal. Screw	487	You can have as many signal watchers per signal as you want.
231	libevent.
232		488
233	The C<signal_ns> variant doesn't add/start the newly created watcher.	489	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
234		490
235	=back	491	=item $w->set ($signal)
236		492
237	=head1 THE EV::Event CLASS	493	Reconfigures the watcher, see the constructor above for details. Can be
		494	called at any time.
238		495
239	All EV functions creating an event watcher (designated by C<my $w =>
240	above) support the following methods on the returned watcher object:
241
242	=over 4
243
244	=item $w->add ($timeout)
245
246	Stops and (re-)starts the event watcher, setting the optional timeout to
247	the given value, or clearing the timeout if none is given.
248
249	=item $w->start
250
251	Stops and (re-)starts the event watcher without touching the timeout.
252
253	=item $w->del
254
255	=item $w->stop
256
257	Stop the event watcher if it was started.
258
259	=item $current_callback = $w->cb
260
261	=item $old_callback = $w->cb ($new_callback)
262
263	Return the previously set callback and optionally set a new one.
264
265	=item $current_fh = $w->fh
266
267	=item $old_fh = $w->fh ($new_fh)
268
269	Returns the previously set filehandle and optionally set a new one (also
270	clears the EV::SIGNAL flag when setting a filehandle).
271
272	=item $current_signal = $w->signal	496	=item $current_signum = $w->signal
273		497
274	=item $old_signal = $w->signal ($new_signal)	498	=item $old_signum = $w->signal ($new_signal)
275		499
		500	Returns the previously set signal (always as a number not name) and
		501	optionally set a new one.
		502
		503	=back
		504
		505
		506	=head3 CHILD WATCHERS - watch out for process status changes
		507
		508	=over 4
		509
		510	=item $w = EV::child $pid, $callback
		511
		512	=item $w = EV::child_ns $pid, $callback
		513
		514	Call the callback when a status change for pid C<$pid> (or any pid if
		515	C<$pid> is 0) has been received. More precisely: when the process receives
		516	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		517	changed/zombie children and call the callback.
		518
		519	It is valid (and fully supported) to install a child watcher after a child
		520	has exited but before the event loop has started its next iteration (for
		521	example, first you C<fork>, then the new child process might exit, and
		522	only then do you install a child watcher in the parent for the new pid).
		523
		524	You can access both exit (or tracing) status and pid by using the
		525	C<rstatus> and C<rpid> methods on the watcher object.
		526
		527	You can have as many pid watchers per pid as you want, they will all be
		528	called.
		529
		530	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		531
		532	=item $w->set ($pid)
		533
		534	Reconfigures the watcher, see the constructor above for details. Can be called at
		535	any time.
		536
		537	=item $current_pid = $w->pid
		538
		539	=item $old_pid = $w->pid ($new_pid)
		540
276	Returns the previously set signal number and optionally set a new one (also sets	541	Returns the previously set process id and optionally set a new one.
277	the EV::SIGNAL flag when setting a signal).
278		542
279	=item $current_eventmask = $w->events	543	=item $exit_status = $w->rstatus
280		544
281	=item $old_eventmask = $w->events ($new_eventmask)	545	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		546	in perlfunc).
282		547
		548	=item $pid = $w->rpid
		549
		550	Return the pid of the awaited child (useful when you have installed a
		551	watcher for all pids).
		552
		553	=back
		554
		555
		556	=head3 IDLE WATCHERS - when you've got nothing better to do...
		557
		558	=over 4
		559
		560	=item $w = EV::idle $callback
		561
		562	=item $w = EV::idle_ns $callback
		563
		564	Call the callback when there are no pending io, timer/periodic, signal or
		565	child events, i.e. when the process is idle.
		566
		567	The process will not block as long as any idle watchers are active, and
		568	they will be called repeatedly until stopped.
		569
		570	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		571
		572	=back
		573
		574
		575	=head3 PREPARE WATCHERS - customise your event loop!
		576
		577	=over 4
		578
		579	=item $w = EV::prepare $callback
		580
		581	=item $w = EV::prepare_ns $callback
		582
		583	Call the callback just before the process would block. You can still
		584	create/modify any watchers at this point.
		585
		586	See the EV::check watcher, below, for explanations and an example.
		587
		588	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		589
		590	=back
		591
		592
		593	=head3 CHECK WATCHERS - customise your event loop even more!
		594
		595	=over 4
		596
		597	=item $w = EV::check $callback
		598
		599	=item $w = EV::check_ns $callback
		600
		601	Call the callback just after the process wakes up again (after it has
		602	gathered events), but before any other callbacks have been invoked.
		603
		604	This is used to integrate other event-based software into the EV
		605	mainloop: You register a prepare callback and in there, you create io and
		606	timer watchers as required by the other software. Here is a real-world
		607	example of integrating Net::SNMP (with some details left out):
		608
		609	our @snmp_watcher;
		610
		611	our $snmp_prepare = EV::prepare sub {
		612	# do nothing unless active
		613	$dispatcher->{_event_queue_h}
		614	or return;
		615
		616	# make the dispatcher handle any outstanding stuff
		617	... not shown
		618
		619	# create an IO watcher for each and every socket
		620	@snmp_watcher = (
		621	(map { EV::io $_, EV::READ, sub { } }
		622	keys %{ $dispatcher->{_descriptors} }),
		623
		624	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		625	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		626	0, sub { },
		627	);
		628	};
		629
		630	The callbacks are irrelevant (and are not even being called), the
		631	only purpose of those watchers is to wake up the process as soon as
		632	one of those events occurs (socket readable, or timer timed out). The
		633	corresponding EV::check watcher will then clean up:
		634
		635	our $snmp_check = EV::check sub {
		636	# destroy all watchers
		637	@snmp_watcher = ();
		638
		639	# make the dispatcher handle any new stuff
		640	... not shown
		641	};
		642
		643	The callbacks of the created watchers will not be called as the watchers
		644	are destroyed before this cna happen (remember EV::check gets called
		645	first).
		646
		647	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		648
		649	=back
		650
		651	=head3 STAT WATCHERS - did the file attributes just change?
		652
		653	=over 4
		654
		655	=item $w = EV::stat $path, $interval, $callback
		656
		657	=item $w = EV::stat_ns $path, $interval, $callback
		658
		659	Call the callback when a file status change has been detected on
		660	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		661	to "path does not exist" is a status change like any other.
		662
		663	The C<$interval> is a recommended polling interval for systems where
		664	OS-supported change notifications don't exist or are not supported. If
		665	you use C<0> then an unspecified default is used (which is highly
		666	recommended!), which is to be expected to be around five seconds usually.
		667
		668	This watcher type is not meant for massive numbers of stat watchers,
		669	as even with OS-supported change notifications, this can be
		670	resource-intensive.
		671
		672	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		673
		674	=item $w->set ($path, $interval)
		675
		676	Reconfigures the watcher, see the constructor above for details. Can be
		677	called at any time.
		678
		679	=item $current_path = $w->path
		680
		681	=item $old_path = $w->path ($new_path)
		682
283	Returns the previously set event mask and optionally set a new one.	683	Returns the previously set path and optionally set a new one.
284		684
285	=item $w->timeout ($after, $repeat)	685	=item $current_interval = $w->interval
286		686
287	Resets the timeout (see C<EV::timer> for details).	687	=item $old_interval = $w->interval ($new_interval)
288		688
289	=item $w->timeout_abs ($at, $interval)	689	Returns the previously set interval and optionally set a new one. Can be
		690	used to query the actual interval used.
290		691
291	Resets the timeout (see C<EV::timer_abs> for details).
292
293	=item $w->priority_set ($priority)
294
295	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
296
297	=back	692	=back
		693
298		694
299	=head1 THREADS	695	=head1 THREADS
300		696
301	Threads are not supported by this in any way. Perl pseudo-threads is evil	697	Threads are not supported by this module in any way. Perl pseudo-threads
302	and must die.	698	is evil stuff and must die. As soon as Perl gains real threads I will work
		699	on thread support for it.
303		700
304	=head1 BUGS	701	=head1 FORK
305		702
306	Lots. Libevent itself isn't well tested and rather buggy, and this module	703	Most of the "improved" event delivering mechanisms of modern operating
307	is quite new at the moment.	704	systems have quite a few problems with fork(2) (to put it bluntly: it is
		705	not supported and usually destructive). Libev makes it possible to work
		706	around this by having a function that recreates the kernel state after
		707	fork in the child.
308		708
309	Please note that the epoll method is not, in general, reliable in programs	709	On non-win32 platforms, this module requires the pthread_atfork
310	that use fork (even if no libveent calls are being made in the forked	710	functionality to do this automatically for you. This function is quite
311	process). If your program behaves erratically, try setting the environment	711	buggy on most BSDs, though, so YMMV. The overhead for this is quite
312	variable C<EVENT_NOEPOLL> first when running the program.	712	negligible, because everything the function currently does is set a flag
		713	that is checked only when the event loop gets used the next time, so when
		714	you do fork but not use EV, the overhead is minimal.
313		715
314	In general, if you fork, then you can only use the EV module in one of the	716	On win32, there is no notion of fork so all this doesn't apply, of course.
315	children.
316		717
317	=cut	718	=cut
318		719
319	our $DIED = sub {	720	our $DIED = sub {
320	warn "EV: error in callback (ignoring): $@";	721	warn "EV: error in callback (ignoring): $@";
321	};	722	};
322		723
323	init;	724	default_loop
324		725	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
325	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
326		726
327	1;	727	1;
328		728
329	=head1 SEE ALSO	729	=head1 SEE ALSO
330		730
331	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	731	L<EV::DNS>.
332	L<EV::AnyEvent>.
333		732
334	=head1 AUTHOR	733	=head1 AUTHOR
335		734
336	Marc Lehmann <schmorp@schmorp.de>	735	Marc Lehmann <schmorp@schmorp.de>
337	http://home.schmorp.de/	736	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.17 by root, Wed Oct 31 21:34:45 2007 UTC vs. Revision 1.55 by root, Tue Nov 27 08:11:52 2007 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.17 by root, Wed Oct 31 21:34:45 2007 UTC vs.
Revision 1.55 by root, Tue Nov 27 08:11:52 2007 UTC