[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 1.59 by root, Sat Dec 1 22:51:34 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 = '1.5';
85	use XSLoader;	73	use XSLoader;
86	XSLoader::load "EV", $VERSION;	74	XSLoader::load "EV", $VERSION;
87	}	75	}
88		76
89	@EV::Io::ISA = "EV::Watcher";	77	@EV::IO::ISA =
90	@EV::Time::ISA = "EV::Watcher";
91	@EV::Timer::ISA = "EV::Time";	78	@EV::Timer::ISA =
92	@EV::Periodic::ISA = "EV::Time";	79	@EV::Periodic::ISA =
93	@EV::Signal::ISA = "EV::Watcher";	80	@EV::Signal::ISA =
94	@EV::Idle::ISA = "EV::Watcher";	81	@EV::Child::ISA =
95	@EV::Prepare::ISA = "EV::Watcher";	82	@EV::Stat::ISA =
96	@EV::Check::ISA = "EV::Watcher";	83	@EV::Idle::ISA =
97	@EV::Child::ISA = "EV::Watcher";	84	@EV::Prepare::ISA =
		85	@EV::Check::ISA =
		86	@EV::Embed::ISA =
		87	@EV::Fork::ISA =
		88	"EV::Watcher";
98		89
99	=head1 BASIC INTERFACE	90	=head1 BASIC INTERFACE
100		91
101	=over 4	92	=over 4
102
103	=item $EV::NPRI
104
105	How many priority levels are available.
106		93
107	=item $EV::DIED	94	=item $EV::DIED
108		95
109	Must contain a reference to a function that is called when a callback	96	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	97	throws an exception (with $@ containing thr error). The default prints an
111	informative message and continues.	98	informative message and continues.
112		99
113	If this callback throws an exception it will be silently ignored.	100	If this callback throws an exception it will be silently ignored.
114		101
		102	=item $time = EV::time
		103
		104	Returns the current time in (fractional) seconds since the epoch.
		105
115	=item $time = EV::now	106	=item $time = EV::now
116		107
117	Returns the time in (fractional) seconds since the epoch.	108	Returns the time the last event loop iteration has been started. This
118		109	is the time that (relative) timers are based on, and refering to it is
119	=item $version = EV::version	110	usually faster then calling EV::time.
120		111
121	=item $method = EV::method	112	=item $method = EV::method
122		113
123	Return version string and event polling method used.	114	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		115	or EV::METHOD_EPOLL).
124		116
125	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	117	=item EV::loop [$flags]
126		118
127	=item EV::loopexit $after	119	Begin checking for events and calling callbacks. It returns when a
		120	callback calls EV::unloop.
128		121
129	Exit any active loop or dispatch after C<$after> seconds or immediately if	122	The $flags argument can be one of the following:
130	C<$after> is missing or zero.
131		123
132	=item EV::dispatch	124	0 as above
		125	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		126	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
133		127
134	Same as C<EV::loop 0>.	128	=item EV::unloop [$how]
135		129
136	=item EV::event $callback	130	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		131	innermost call to EV::loop return.
137		132
138	Creates a new event watcher waiting for nothing, calling the given callback.	133	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		134	fast as possible.
139		135
		136	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		137
		138	This function rolls together an I/O and a timer watcher for a single
		139	one-shot event without the need for managing a watcher object.
		140
		141	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		142	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		143	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		144	you do not want to wait for some I/O event, specify C<undef> for
		145	C<$fh_or_undef> and C<0> for C<$events>).
		146
		147	If timeout is C<undef> or negative, then there will be no
		148	timeout. Otherwise a EV::timer with this value will be started.
		149
		150	When an error occurs or either the timeout or I/O watcher triggers, then
		151	the callback will be called with the received event set (in general
		152	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		153	C<EV::WRITE> and C<EV::TIMEOUT>).
		154
		155	EV::once doesn't return anything: the watchers stay active till either
		156	of them triggers, then they will be stopped and freed, and the callback
		157	invoked.
		158
		159	=back
		160
		161	=head2 WATCHER OBJECTS
		162
		163	A watcher is an object that gets created to record your interest in some
		164	event. For instance, if you want to wait for STDIN to become readable, you
		165	would create an EV::io watcher for that:
		166
		167	my $watcher = EV::io *STDIN, EV::READ, sub {
		168	my ($watcher, $revents) = @_;
		169	warn "yeah, STDIN should not be readable without blocking!\n"
		170	};
		171
		172	All watchers can be active (waiting for events) or inactive (paused). Only
		173	active watchers will have their callbacks invoked. All callbacks will be
		174	called with at least two arguments: the watcher and a bitmask of received
		175	events.
		176
		177	Each watcher type has its associated bit in revents, so you can use the
		178	same callback for multiple watchers. The event mask is named after the
		179	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		180	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		181	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		182	uses EV::TIMEOUT).
		183
		184	In the rare case where one wants to create a watcher but not start it at
		185	the same time, each constructor has a variant with a trailing C<_ns> in
		186	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		187
		188	Please note that a watcher will automatically be stopped when the watcher
		189	object is destroyed, so you I<need> to keep the watcher objects returned by
		190	the constructors.
		191
		192	Also, all methods changing some aspect of a watcher (->set, ->priority,
		193	->fh and so on) automatically stop and start it again if it is active,
		194	which means pending events get lost.
		195
		196	=head2 COMMON WATCHER METHODS
		197
		198	This section lists methods common to all watchers.
		199
		200	=over 4
		201
		202	=item $w->start
		203
		204	Starts a watcher if it isn't active already. Does nothing to an already
		205	active watcher. By default, all watchers start out in the active state
		206	(see the description of the C<_ns> variants if you need stopped watchers).
		207
		208	=item $w->stop
		209
		210	Stop a watcher if it is active. Also clear any pending events (events that
		211	have been received but that didn't yet result in a callback invocation),
		212	regardless of wether the watcher was active or not.
		213
		214	=item $bool = $w->is_active
		215
		216	Returns true if the watcher is active, false otherwise.
		217
		218	=item $current_data = $w->data
		219
		220	=item $old_data = $w->data ($new_data)
		221
		222	Queries a freely usable data scalar on the watcher and optionally changes
		223	it. This is a way to associate custom data with a watcher:
		224
		225	my $w = EV::timer 60, 0, sub {
		226	warn $_[0]->data;
		227	};
		228	$w->data ("print me!");
		229
		230	=item $current_cb = $w->cb
		231
		232	=item $old_cb = $w->cb ($new_cb)
		233
		234	Queries the callback on the watcher and optionally changes it. You can do
		235	this at any time without the watcher restarting.
		236
		237	=item $current_priority = $w->priority
		238
		239	=item $old_priority = $w->priority ($new_priority)
		240
		241	Queries the priority on the watcher and optionally changes it. Pending
		242	watchers with higher priority will be invoked first. The valid range of
		243	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		244	-2). If the priority is outside this range it will automatically be
		245	normalised to the nearest valid priority.
		246
		247	The default priority of any newly-created watcher is 0.
		248
		249	Note that the priority semantics have not yet been fleshed out and are
		250	subject to almost certain change.
		251
		252	=item $w->trigger ($revents)
		253
		254	Call the callback now with the given event mask.
		255
		256	=item $previous_state = $w->keepalive ($bool)
		257
		258	Normally, C<EV::loop> will return when there are no active watchers
		259	(which is a "deadlock" because no progress can be made anymore). This is
		260	convinient because it allows you to start your watchers (and your jobs),
		261	call C<EV::loop> once and when it returns you know that all your jobs are
		262	finished (or they forgot to register some watchers for their task :).
		263
		264	Sometimes, however, this gets in your way, for example when you the module
		265	that calls C<EV::loop> (usually the main program) is not the same module
		266	as a long-living watcher (for example a DNS client module written by
		267	somebody else even). Then you might want any outstanding requests to be
		268	handled, but you would not want to keep C<EV::loop> from returning just
		269	because you happen to have this long-running UDP port watcher.
		270
		271	In this case you can clear the keepalive status, which means that even
		272	though your watcher is active, it won't keep C<EV::loop> from returning.
		273
		274	The initial value for keepalive is true (enabled), and you cna change it
		275	any time.
		276
		277	Example: Register an IO watcher for some UDP socket but do not keep the
		278	event loop from running just because of that watcher.
		279
		280	my $udp_socket = ...
		281	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		282	$udp_watcher->keepalive (0);
		283
		284	=back
		285
		286
		287	=head2 WATCHER TYPES
		288
		289	Each of the following subsections describes a single watcher type.
		290
		291	=head3 IO WATCHERS - is this file descriptor readable or writable?
		292
		293	=over 4
		294
140	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	295	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
141		296
142	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	297	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
143		298
144	As long as the returned watcher object is alive, call the C<$callback>	299	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	300	when at least one of events specified in C<$eventmask> occurs.
146	is disabled.
147		301
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:	302	The $eventmask can be one or more of these constants ORed together:
157		303
158	EV::READ wait until read() wouldn't block anymore	304	EV::READ wait until read() wouldn't block anymore
159	EV::WRITE wait until write() wouldn't block anymore	305	EV::WRITE wait until write() wouldn't block anymore
160	EV::PERSIST stay active after a (non-timeout) event occured
161		306
162	The C<io_ns> variant doesn't add/start the newly created watcher.	307	The C<io_ns> variant doesn't start (activate) the newly created watcher.
163		308
164	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	309	=item $w->set ($fileno_or_fh, $eventmask)
165		310
166	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	311	Reconfigures the watcher, see the constructor above for details. Can be
		312	called at any time.
167		313
168	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	314	=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		315
172	If the timeout is zero or undef, no timeout will be set, and a normal	316	=item $old_fh = $w->fh ($new_fh)
173	watcher (with the persist flag set!) will be created.
174		317
175	This has the effect of timing out after the specified period of inactivity	318	Returns the previously set filehandle and optionally set a new one.
176	has happened.
177		319
178	Due to the design of libevent, this is also relatively inefficient, having	320	=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		321
		322	=item $old_eventmask = $w->events ($new_eventmask)
		323
		324	Returns the previously set event mask and optionally set a new one.
		325
		326	=back
		327
		328
		329	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		330
		331	=over 4
		332
182	=item my $w = EV::timer $after, $repeat, $callback	333	=item $w = EV::timer $after, $repeat, $callback
183		334
184	=item my $w = EV::timer_ns $after, $repeat, $callback	335	=item $w = EV::timer_ns $after, $repeat, $callback
185		336
186	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	337	Calls the callback after C<$after> seconds (which may be fractional). If
187	timer will be restarted after the callback returns. This means that the	338	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	339	value as $after) after the callback returns.
189	time the callback takes.
190		340
		341	This means that the callback would be called roughly after C<$after>
		342	seconds, and then every C<$repeat> seconds. The timer does his best not
		343	to drift, but it will not invoke the timer more often then once per event
		344	loop iteration, and might drift in other cases. If that isn't acceptable,
		345	look at EV::periodic, which can provide long-term stable timers.
		346
		347	The timer is based on a monotonic clock, that is, if somebody is sitting
		348	in front of the machine while the timer is running and changes the system
		349	clock, the timer will nevertheless run (roughly) the same time.
		350
191	The C<timer_ns> variant doesn't add/start the newly created watcher.	351	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
192		352
193	=item my $w = EV::timer_abs $at, $interval, $callback	353	=item $w->set ($after, $repeat)
194		354
195	=item my $w = EV::timer_abs_ns $at, $interval, $callback	355	Reconfigures the watcher, see the constructor above for details. Can be called at
		356	any time.
196		357
197	Similar to EV::timer, but the time is given as an absolute point in time	358	=item $w->again
198	(C<$at>), plus an optional C<$interval>.
199		359
200	If the C<$interval> is zero, then the callback will be called at the time	360	Similar to the C<start> method, but has special semantics for repeating timers:
201	C<$at> if that is in the future, or as soon as possible if its in the
202	past. It will not automatically repeat.
203		361
204	If the C<$interval> is nonzero, then the watcher will always be scheduled	362	If the timer is active and non-repeating, it will be stopped.
205	to time out at the next C<$at + integer * $interval> time.
206		363
207	This can be used to schedule a callback to run at very regular intervals,	364	If the timer is active and repeating, reset the timeout to occur
208	as long as the processing time is less then the interval (otherwise	365	C<$repeat> seconds after now.
209	obviously events will be skipped).	366
		367	If the timer is inactive and repeating, start it using the repeat value.
		368
		369	Otherwise do nothing.
		370
		371	This behaviour is useful when you have a timeout for some IO
		372	operation. You create a timer object with the same value for C<$after> and
		373	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		374	on the timeout.
		375
		376	=back
		377
		378
		379	=head3 PERIODIC WATCHERS - to cron or not to cron?
		380
		381	=over 4
		382
		383	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		384
		385	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		386
		387	Similar to EV::timer, but is not based on relative timeouts but on
		388	absolute times. Apart from creating "simple" timers that trigger "at" the
		389	specified time, it can also be used for non-drifting absolute timers and
		390	more complex, cron-like, setups that are not adversely affected by time
		391	jumps (i.e. when the system clock is changed by explicit date -s or other
		392	means such as ntpd). It is also the most complex watcher type in EV.
		393
		394	It has three distinct "modes":
		395
		396	=over 4
		397
		398	=item * absolute timer ($interval = $reschedule_cb = 0)
		399
		400	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		401	will not adjust when a time jump occurs, that is, if it is to be run
		402	at January 1st 2011 then it will run when the system time reaches or
		403	surpasses this time.
		404
		405	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		406
		407	In this mode the watcher will always be scheduled to time out at the
		408	next C<$at + N * $interval> time (for some integer N) and then repeat,
		409	regardless of any time jumps.
		410
		411	This can be used to create timers that do not drift with respect to system
		412	time:
		413
		414	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		415
		416	That doesn't mean there will always be 3600 seconds in between triggers,
		417	but only that the the clalback will be called when the system time shows a
		418	full hour (UTC).
210		419
211	Another way to think about it (for the mathematically inclined) is that	420	Another way to think about it (for the mathematically inclined) is that
212	C<timer_abs> will try to tun the callback at the next possible time where	421	EV::periodic will try to run the callback in this mode at the next
213	C<$time = $at (mod $interval)>, regardless of any time jumps.	422	possible time where C<$time = $at (mod $interval)>, regardless of any time
		423	jumps.
214		424
		425	=item * manual reschedule mode ($reschedule_cb = coderef)
		426
		427	In this mode $interval and $at are both being ignored. Instead, each
		428	time the periodic watcher gets scheduled, the reschedule callback
		429	($reschedule_cb) will be called with the watcher as first, and the current
		430	time as second argument.
		431
		432	I<This callback MUST NOT stop or destroy this or any other periodic
		433	watcher, ever>. If you need to stop it, return 1e30 and stop it
		434	afterwards.
		435
		436	It must return the next time to trigger, based on the passed time value
		437	(that is, the lowest time value larger than to the second argument). It
		438	will usually be called just before the callback will be triggered, but
		439	might be called at other times, too.
		440
		441	This can be used to create very complex timers, such as a timer that
		442	triggers on each midnight, local time (actually 24 hours after the last
		443	midnight, to keep the example simple. If you know a way to do it correctly
		444	in about the same space (without requiring elaborate modules), drop me a
		445	note :):
		446
		447	my $daily = EV::periodic 0, 0, sub {
		448	my ($w, $now) = @_;
		449
		450	use Time::Local ();
		451	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		452	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		453	}, sub {
		454	print "it's midnight or likely shortly after, now\n";
		455	};
		456
		457	=back
		458
215	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	459	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
216		460
		461	=item $w->set ($at, $interval, $reschedule_cb)
		462
		463	Reconfigures the watcher, see the constructor above for details. Can be called at
		464	any time.
		465
		466	=item $w->again
		467
		468	Simply stops and starts the watcher again.
		469
		470	=back
		471
		472
		473	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		474
		475	=over 4
		476
217	=item my $w = EV::signal $signal, $callback	477	=item $w = EV::signal $signal, $callback
218		478
219	=item my $w = EV::signal_ns $signal, $callback	479	=item $w = EV::signal_ns $signal, $callback
220		480
221	Call the callback when $signal is received (the signal can be specified	481	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	482	number or by name, just as with C<kill> or C<%SIG>).
223	persistent no natter what.
224		483
225	EV will grab the signal for the process (the kernel only allows one	484	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	485	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	486	and removes it again when you stop it. Perl does the same when you
228	callbacks to %SIG, so watch out.	487	add/remove callbacks to C<%SIG>, so watch out.
229		488
230	Unfortunately, only one handler can be registered per signal. Screw	489	You can have as many signal watchers per signal as you want.
231	libevent.
232		490
233	The C<signal_ns> variant doesn't add/start the newly created watcher.	491	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
234		492
235	=back	493	=item $w->set ($signal)
236		494
237	=head1 THE EV::Event CLASS	495	Reconfigures the watcher, see the constructor above for details. Can be
		496	called at any time.
238		497
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	498	=item $current_signum = $w->signal
273		499
274	=item $old_signal = $w->signal ($new_signal)	500	=item $old_signum = $w->signal ($new_signal)
275		501
		502	Returns the previously set signal (always as a number not name) and
		503	optionally set a new one.
		504
		505	=back
		506
		507
		508	=head3 CHILD WATCHERS - watch out for process status changes
		509
		510	=over 4
		511
		512	=item $w = EV::child $pid, $callback
		513
		514	=item $w = EV::child_ns $pid, $callback
		515
		516	Call the callback when a status change for pid C<$pid> (or any pid if
		517	C<$pid> is 0) has been received. More precisely: when the process receives
		518	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		519	changed/zombie children and call the callback.
		520
		521	It is valid (and fully supported) to install a child watcher after a child
		522	has exited but before the event loop has started its next iteration (for
		523	example, first you C<fork>, then the new child process might exit, and
		524	only then do you install a child watcher in the parent for the new pid).
		525
		526	You can access both exit (or tracing) status and pid by using the
		527	C<rstatus> and C<rpid> methods on the watcher object.
		528
		529	You can have as many pid watchers per pid as you want, they will all be
		530	called.
		531
		532	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		533
		534	=item $w->set ($pid)
		535
		536	Reconfigures the watcher, see the constructor above for details. Can be called at
		537	any time.
		538
		539	=item $current_pid = $w->pid
		540
		541	=item $old_pid = $w->pid ($new_pid)
		542
276	Returns the previously set signal number and optionally set a new one (also sets	543	Returns the previously set process id and optionally set a new one.
277	the EV::SIGNAL flag when setting a signal).
278		544
279	=item $current_eventmask = $w->events	545	=item $exit_status = $w->rstatus
280		546
281	=item $old_eventmask = $w->events ($new_eventmask)	547	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		548	in perlfunc).
282		549
		550	=item $pid = $w->rpid
		551
		552	Return the pid of the awaited child (useful when you have installed a
		553	watcher for all pids).
		554
		555	=back
		556
		557
		558	=head3 STAT WATCHERS - did the file attributes just change?
		559
		560	=over 4
		561
		562	=item $w = EV::stat $path, $interval, $callback
		563
		564	=item $w = EV::stat_ns $path, $interval, $callback
		565
		566	Call the callback when a file status change has been detected on
		567	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		568	to "path does not exist" is a status change like any other.
		569
		570	The C<$interval> is a recommended polling interval for systems where
		571	OS-supported change notifications don't exist or are not supported. If
		572	you use C<0> then an unspecified default is used (which is highly
		573	recommended!), which is to be expected to be around five seconds usually.
		574
		575	This watcher type is not meant for massive numbers of stat watchers,
		576	as even with OS-supported change notifications, this can be
		577	resource-intensive.
		578
		579	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		580
		581	=item ... = $w->stat
		582
		583	This call is very similar to the perl C<stat> built-in: It stats (using
		584	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		585	well as EV's idea of the current stat values) to the values found.
		586
		587	In scalar context, a boolean is return indicating success or failure of
		588	the stat. In list context, the same 13-value list as with stat is returned
		589	(except that the blksize and blocks fields are not reliable).
		590
		591	In the case of an error, errno is set to C<ENOENT> (regardless of the
		592	actual error value) and the C<nlink> value is forced to zero (if the stat
		593	was successful then nlink is guaranteed to be non-zero).
		594
		595	See also the next two entries for more info.
		596
		597	=item ... = $w->attr
		598
		599	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		600	the values most recently detected by EV. See the next entry for more info.
		601
		602	=item ... = $w->prev
		603
		604	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		605	the previous set of values, before the change.
		606
		607	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		608	to the values found I<before> a change was detected, while C<< $w->attr >>
		609	returns the values found leading to the change detection. The difference (if any)
		610	between C<prev> and C<attr> is what triggered the callback.
		611
		612	If you did something to the filesystem object and do not want to trigger
		613	yet another change, you can call C<stat> to update EV's idea of what the
		614	current attributes are.
		615
		616	=item $w->set ($path, $interval)
		617
		618	Reconfigures the watcher, see the constructor above for details. Can be
		619	called at any time.
		620
		621	=item $current_path = $w->path
		622
		623	=item $old_path = $w->path ($new_path)
		624
283	Returns the previously set event mask and optionally set a new one.	625	Returns the previously set path and optionally set a new one.
284		626
285	=item $w->timeout ($after, $repeat)	627	=item $current_interval = $w->interval
286		628
287	Resets the timeout (see C<EV::timer> for details).	629	=item $old_interval = $w->interval ($new_interval)
288		630
289	=item $w->timeout_abs ($at, $interval)	631	Returns the previously set interval and optionally set a new one. Can be
		632	used to query the actual interval used.
290		633
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	634	=back
		635
		636
		637	=head3 IDLE WATCHERS - when you've got nothing better to do...
		638
		639	=over 4
		640
		641	=item $w = EV::idle $callback
		642
		643	=item $w = EV::idle_ns $callback
		644
		645	Call the callback when there are no pending io, timer/periodic, signal or
		646	child events, i.e. when the process is idle.
		647
		648	The process will not block as long as any idle watchers are active, and
		649	they will be called repeatedly until stopped.
		650
		651	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		652
		653	=back
		654
		655
		656	=head3 PREPARE WATCHERS - customise your event loop!
		657
		658	=over 4
		659
		660	=item $w = EV::prepare $callback
		661
		662	=item $w = EV::prepare_ns $callback
		663
		664	Call the callback just before the process would block. You can still
		665	create/modify any watchers at this point.
		666
		667	See the EV::check watcher, below, for explanations and an example.
		668
		669	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		670
		671	=back
		672
		673
		674	=head3 CHECK WATCHERS - customise your event loop even more!
		675
		676	=over 4
		677
		678	=item $w = EV::check $callback
		679
		680	=item $w = EV::check_ns $callback
		681
		682	Call the callback just after the process wakes up again (after it has
		683	gathered events), but before any other callbacks have been invoked.
		684
		685	This is used to integrate other event-based software into the EV
		686	mainloop: You register a prepare callback and in there, you create io and
		687	timer watchers as required by the other software. Here is a real-world
		688	example of integrating Net::SNMP (with some details left out):
		689
		690	our @snmp_watcher;
		691
		692	our $snmp_prepare = EV::prepare sub {
		693	# do nothing unless active
		694	$dispatcher->{_event_queue_h}
		695	or return;
		696
		697	# make the dispatcher handle any outstanding stuff
		698	... not shown
		699
		700	# create an IO watcher for each and every socket
		701	@snmp_watcher = (
		702	(map { EV::io $_, EV::READ, sub { } }
		703	keys %{ $dispatcher->{_descriptors} }),
		704
		705	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		706	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		707	0, sub { },
		708	);
		709	};
		710
		711	The callbacks are irrelevant (and are not even being called), the
		712	only purpose of those watchers is to wake up the process as soon as
		713	one of those events occurs (socket readable, or timer timed out). The
		714	corresponding EV::check watcher will then clean up:
		715
		716	our $snmp_check = EV::check sub {
		717	# destroy all watchers
		718	@snmp_watcher = ();
		719
		720	# make the dispatcher handle any new stuff
		721	... not shown
		722	};
		723
		724	The callbacks of the created watchers will not be called as the watchers
		725	are destroyed before this cna happen (remember EV::check gets called
		726	first).
		727
		728	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		729
		730	=back
		731
		732
		733	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		734
		735	Fork watchers are called when a C<fork ()> was detected. The invocation
		736	is done before the event loop blocks next and before C<check> watchers
		737	are being called, and only in the child after the fork.
		738
		739	=over 4
		740
		741	=item $w = EV::fork $callback
		742
		743	=item $w = EV::fork_ns $callback
		744
		745	Call the callback before the event loop is resumed in the child process
		746	after a fork.
		747
		748	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		749
		750	=back
		751
298		752
299	=head1 THREADS	753	=head1 THREADS
300		754
301	Threads are not supported by this in any way. Perl pseudo-threads is evil	755	Threads are not supported by this module in any way. Perl pseudo-threads
302	and must die.	756	is evil stuff and must die. As soon as Perl gains real threads I will work
		757	on thread support for it.
303		758
304	=head1 BUGS	759	=head1 FORK
305		760
306	Lots. Libevent itself isn't well tested and rather buggy, and this module	761	Most of the "improved" event delivering mechanisms of modern operating
307	is quite new at the moment.	762	systems have quite a few problems with fork(2) (to put it bluntly: it is
		763	not supported and usually destructive). Libev makes it possible to work
		764	around this by having a function that recreates the kernel state after
		765	fork in the child.
308		766
309	Please note that the epoll method is not, in general, reliable in programs	767	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	768	functionality to do this automatically for you. This function is quite
311	process). If your program behaves erratically, try setting the environment	769	buggy on most BSDs, though, so YMMV. The overhead for this is quite
312	variable C<EVENT_NOEPOLL> first when running the program.	770	negligible, because everything the function currently does is set a flag
		771	that is checked only when the event loop gets used the next time, so when
		772	you do fork but not use EV, the overhead is minimal.
313		773
314	In general, if you fork, then you can only use the EV module in one of the	774	On win32, there is no notion of fork so all this doesn't apply, of course.
315	children.
316		775
317	=cut	776	=cut
318		777
319	our $DIED = sub {	778	our $DIED = sub {
320	warn "EV: error in callback (ignoring): $@";	779	warn "EV: error in callback (ignoring): $@";
321	};	780	};
322		781
323	init;	782	default_loop
324		783	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
325	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
326		784
327	1;	785	1;
328		786
329	=head1 SEE ALSO	787	=head1 SEE ALSO
330		788
331	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	789	L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
332	L<EV::AnyEvent>.	790	event loop), L<Coro::EV> (efficient coroutines with EV).
333		791
334	=head1 AUTHOR	792	=head1 AUTHOR
335		793
336	Marc Lehmann <schmorp@schmorp.de>	794	Marc Lehmann <schmorp@schmorp.de>
337	http://home.schmorp.de/	795	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 1.59 by root, Sat Dec 1 22:51:34 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 1.59 by root, Sat Dec 1 22:51:34 2007 UTC