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

Comparing EV/EV.pm (file contents):
Revision 1.19 by root, Thu Nov 1 11:43:10 2007 UTC vs.
Revision 1.96 by root, Thu May 22 02:44:57 2008 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
54	my $w = EV::signal 3, sub {	38	# CHILD/PID STATUS CHANGES
55	warn "sigquit received (this is GNU/Linux, right?)\n";	39
		40	my $w = EV::child 666, 0, sub {
		41	my ($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://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
		62	subtle details on watcher semantics or some discussion on the available
		63	backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
		64	about in any case because it has much more detailed information.
		65
		66	This module is very fast and scalable. It is actually so fast that you
		67	can use it through the L<AnyEvent> module, stay portable to other event
		68	loops (if you don't rely on any watcher types not available through it)
		69	and still be faster than with any other event loop currently supported in
		70	Perl.
76		71
77	=cut	72	=cut
78		73
79	package EV;	74	package EV;
80		75
81	use strict;	76	use strict;
82		77
83	BEGIN {	78	BEGIN {
84	our $VERSION = '0.1';	79	our $VERSION = '3.41';
85	use XSLoader;	80	use XSLoader;
86	XSLoader::load "EV", $VERSION;	81	XSLoader::load "EV", $VERSION;
87	}	82	}
88		83
89	@EV::Io::ISA =	84	@EV::IO::ISA =
90	@EV::Timer::ISA =	85	@EV::Timer::ISA =
91	@EV::Periodic::ISA =	86	@EV::Periodic::ISA =
92	@EV::Signal::ISA =	87	@EV::Signal::ISA =
		88	@EV::Child::ISA =
		89	@EV::Stat::ISA =
93	@EV::Idle::ISA =	90	@EV::Idle::ISA =
94	@EV::Prepare::ISA =	91	@EV::Prepare::ISA =
95	@EV::Check::ISA =	92	@EV::Check::ISA =
96	@EV::Child::ISA = "EV::Watcher";	93	@EV::Embed::ISA =
		94	@EV::Fork::ISA =
		95	@EV::Async::ISA =
		96	"EV::Watcher";
		97
		98	@EV::Loop::Default::ISA = "EV::Loop";
		99
		100	=head1 EVENT LOOPS
		101
		102	EV supports multiple event loops: There is a single "default event loop"
		103	that can handle everything including signals and child watchers, and any
		104	number of "dynamic event loops" that can use different backends (with
		105	various limitations), but no child and signal watchers.
		106
		107	You do not have to do anything to create the default event loop: When
		108	the module is loaded a suitable backend is selected on the premise of
		109	selecting a working backend (which for example rules out kqueue on most
		110	BSDs). Modules should, unless they have "special needs" always use the
		111	default loop as this is fastest (perl-wise), best supported by other
		112	modules (e.g. AnyEvent or Coro) and most portable event loop.
		113
		114	For specific programs you can create additional event loops dynamically.
		115
		116	=over 4
		117
		118	=item $loop = new EV::loop [$flags]
		119
		120	Create a new event loop as per the specified flags. Please refer to the
		121	C<ev_loop_new ()> function description in the libev documentation
		122	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		123	for more info.
		124
		125	The loop will automatically be destroyed when it is no longer referenced
		126	by any watcher and the loop object goes out of scope.
		127
		128	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		129	is protected by this module.
		130
		131	=item $loop->loop_fork
		132
		133	Must be called after a fork in the child, before entering or continuing
		134	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		135	this function automatically, at some performance loss (refer to the libev
		136	documentation).
		137
		138	=item $loop->loop_verify
		139
		140	Calls C<ev_verify> to make internal consistency checks (for debugging
		141	libev) and abort the program if any data structures wree found to be
		142	corrupted.
		143
		144	=item $loop = EV::default_loop [$flags]
		145
		146	Return the default loop (which is a singleton object). Since this module
		147	already creates the default loop with default flags, specifying flags here
		148	will not have any effect unless you destroy the default loop.
		149
		150	=back
		151
97		152
98	=head1 BASIC INTERFACE	153	=head1 BASIC INTERFACE
99		154
100	=over 4	155	=over 4
101		156
102	=item $EV::NPRI
103
104	How many priority levels are available.
105
106	=item $EV::DIED	157	=item $EV::DIED
107		158
108	Must contain a reference to a function that is called when a callback	159	Must contain a reference to a function that is called when a callback
109	throws an exception (with $@ containing thr error). The default prints an	160	throws an exception (with $@ containing the error). The default prints an
110	informative message and continues.	161	informative message and continues.
111		162
112	If this callback throws an exception it will be silently ignored.	163	If this callback throws an exception it will be silently ignored.
113		164
		165	=item $flags = EV::supported_backends
		166
		167	=item $flags = EV::recommended_backends
		168
		169	=item $flags = EV::embeddable_backends
		170
		171	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		172	instance of EV, the set of recommended backends (supposed to be good) for
		173	this platform and the set of embeddable backends (see EMBED WATCHERS).
		174
		175	=item EV::sleep $seconds
		176
		177	Block the process for the given number of (fractional) seconds.
		178
		179	=item $time = EV::time
		180
		181	Returns the current time in (fractional) seconds since the epoch.
		182
114	=item $time = EV::now	183	=item $time = EV::now
115		184
116	Returns the time in (fractional) seconds since the epoch.	185	=item $time = $loop->now
117		186
118	=item $version = EV::version	187	Returns the time the last event loop iteration has been started. This
		188	is the time that (relative) timers are based on, and refering to it is
		189	usually faster then calling EV::time.
119		190
120	=item $method = EV::method	191	=item $backend = EV::backend
121		192
122	Return version string and event polling method used.	193	=item $backend = $loop->backend
123		194
124	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	195	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		196	or EV::METHOD_EPOLL).
125		197
126	=item EV::loopexit $after	198	=item EV::loop [$flags]
127		199
128	Exit any active loop or dispatch after C<$after> seconds or immediately if	200	=item $loop->loop ([$flags])
129	C<$after> is missing or zero.
130		201
131	=item EV::dispatch	202	Begin checking for events and calling callbacks. It returns when a
		203	callback calls EV::unloop.
132		204
133	Same as C<EV::loop 0>.	205	The $flags argument can be one of the following:
134		206
135	=item EV::event $callback	207	0 as above
		208	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		209	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
136		210
137	Creates a new event watcher waiting for nothing, calling the given callback.	211	=item EV::unloop [$how]
138		212
		213	=item $loop->unloop ([$how])
		214
		215	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		216	innermost call to EV::loop return.
		217
		218	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		219	fast as possible.
		220
		221	=item $count = EV::loop_count
		222
		223	=item $count = $loop->loop_count
		224
		225	Return the number of times the event loop has polled for new
		226	events. Sometiems useful as a generation counter.
		227
		228	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		229
		230	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		231
		232	This function rolls together an I/O and a timer watcher for a single
		233	one-shot event without the need for managing a watcher object.
		234
		235	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		236	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		237	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		238	you do not want to wait for some I/O event, specify C<undef> for
		239	C<$fh_or_undef> and C<0> for C<$events>).
		240
		241	If timeout is C<undef> or negative, then there will be no
		242	timeout. Otherwise a EV::timer with this value will be started.
		243
		244	When an error occurs or either the timeout or I/O watcher triggers, then
		245	the callback will be called with the received event set (in general
		246	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		247	C<EV::WRITE> and C<EV::TIMEOUT>).
		248
		249	EV::once doesn't return anything: the watchers stay active till either
		250	of them triggers, then they will be stopped and freed, and the callback
		251	invoked.
		252
		253	=item EV::feed_fd_event ($fd, $revents)
		254
		255	=item $loop->feed_fd_event ($fd, $revents)
		256
		257	Feed an event on a file descriptor into EV. EV will react to this call as
		258	if the readyness notifications specified by C<$revents> (a combination of
		259	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		260
		261	=item EV::feed_signal_event ($signal)
		262
		263	Feed a signal event into EV. EV will react to this call as if the signal
		264	specified by C<$signal> had occured.
		265
		266	=item EV::set_io_collect_interval $time
		267
		268	=item $loop->set_io_collect_interval ($time)
		269
		270	=item EV::set_timeout_collect_interval $time
		271
		272	=item $loop->set_timeout_collect_interval ($time)
		273
		274	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		275	wait interval for timer events. See the libev documentation at
		276	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		277	a more detailed discussion.
		278
		279	=back
		280
		281
		282	=head1 WATCHER OBJECTS
		283
		284	A watcher is an object that gets created to record your interest in some
		285	event. For instance, if you want to wait for STDIN to become readable, you
		286	would create an EV::io watcher for that:
		287
		288	my $watcher = EV::io *STDIN, EV::READ, sub {
		289	my ($watcher, $revents) = @_;
		290	warn "yeah, STDIN should now be readable without blocking!\n"
		291	};
		292
		293	All watchers can be active (waiting for events) or inactive (paused). Only
		294	active watchers will have their callbacks invoked. All callbacks will be
		295	called with at least two arguments: the watcher and a bitmask of received
		296	events.
		297
		298	Each watcher type has its associated bit in revents, so you can use the
		299	same callback for multiple watchers. The event mask is named after the
		300	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		301	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		302	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		303	uses EV::TIMEOUT).
		304
		305	In the rare case where one wants to create a watcher but not start it at
		306	the same time, each constructor has a variant with a trailing C<_ns> in
		307	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		308
		309	Please note that a watcher will automatically be stopped when the watcher
		310	object is destroyed, so you I<need> to keep the watcher objects returned by
		311	the constructors.
		312
		313	Also, all methods changing some aspect of a watcher (->set, ->priority,
		314	->fh and so on) automatically stop and start it again if it is active,
		315	which means pending events get lost.
		316
		317	=head2 COMMON WATCHER METHODS
		318
		319	This section lists methods common to all watchers.
		320
		321	=over 4
		322
		323	=item $w->start
		324
		325	Starts a watcher if it isn't active already. Does nothing to an already
		326	active watcher. By default, all watchers start out in the active state
		327	(see the description of the C<_ns> variants if you need stopped watchers).
		328
		329	=item $w->stop
		330
		331	Stop a watcher if it is active. Also clear any pending events (events that
		332	have been received but that didn't yet result in a callback invocation),
		333	regardless of whether the watcher was active or not.
		334
		335	=item $bool = $w->is_active
		336
		337	Returns true if the watcher is active, false otherwise.
		338
		339	=item $current_data = $w->data
		340
		341	=item $old_data = $w->data ($new_data)
		342
		343	Queries a freely usable data scalar on the watcher and optionally changes
		344	it. This is a way to associate custom data with a watcher:
		345
		346	my $w = EV::timer 60, 0, sub {
		347	warn $_[0]->data;
		348	};
		349	$w->data ("print me!");
		350
		351	=item $current_cb = $w->cb
		352
		353	=item $old_cb = $w->cb ($new_cb)
		354
		355	Queries the callback on the watcher and optionally changes it. You can do
		356	this at any time without the watcher restarting.
		357
		358	=item $current_priority = $w->priority
		359
		360	=item $old_priority = $w->priority ($new_priority)
		361
		362	Queries the priority on the watcher and optionally changes it. Pending
		363	watchers with higher priority will be invoked first. The valid range of
		364	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		365	-2). If the priority is outside this range it will automatically be
		366	normalised to the nearest valid priority.
		367
		368	The default priority of any newly-created watcher is 0.
		369
		370	Note that the priority semantics have not yet been fleshed out and are
		371	subject to almost certain change.
		372
		373	=item $w->invoke ($revents)
		374
		375	Call the callback now with the given event mask.
		376
		377	=item $w->feed_event ($revents)
		378
		379	Feed some events on this watcher into EV. EV will react to this call as if
		380	the watcher had received the given C<$revents> mask.
		381
		382	=item $revents = $w->clear_pending
		383
		384	If the watcher is pending, this function clears its pending status and
		385	returns its C<$revents> bitset (as if its callback was invoked). If the
		386	watcher isn't pending it does nothing and returns C<0>.
		387
		388	=item $previous_state = $w->keepalive ($bool)
		389
		390	Normally, C<EV::loop> will return when there are no active watchers
		391	(which is a "deadlock" because no progress can be made anymore). This is
		392	convinient because it allows you to start your watchers (and your jobs),
		393	call C<EV::loop> once and when it returns you know that all your jobs are
		394	finished (or they forgot to register some watchers for their task :).
		395
		396	Sometimes, however, this gets in your way, for example when the module
		397	that calls C<EV::loop> (usually the main program) is not the same module
		398	as a long-living watcher (for example a DNS client module written by
		399	somebody else even). Then you might want any outstanding requests to be
		400	handled, but you would not want to keep C<EV::loop> from returning just
		401	because you happen to have this long-running UDP port watcher.
		402
		403	In this case you can clear the keepalive status, which means that even
		404	though your watcher is active, it won't keep C<EV::loop> from returning.
		405
		406	The initial value for keepalive is true (enabled), and you cna change it
		407	any time.
		408
		409	Example: Register an I/O watcher for some UDP socket but do not keep the
		410	event loop from running just because of that watcher.
		411
		412	my $udp_socket = ...
		413	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		414	$1000udp_watcher->keepalive (0);
		415
		416	=item $loop = $w->loop
		417
		418	Return the loop that this watcher is attached to.
		419
		420	=back
		421
		422
		423	=head1 WATCHER TYPES
		424
		425	Each of the following subsections describes a single watcher type.
		426
		427	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		428
		429	=over 4
		430
139	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	431	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
140		432
141	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	433	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		434
		435	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		436
		437	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
142		438
143	As long as the returned watcher object is alive, call the C<$callback>	439	As long as the returned watcher object is alive, call the C<$callback>
144	when the events specified in C<$eventmask> happen. Initially, the timeout	440	when at least one of events specified in C<$eventmask> occurs.
145	is disabled.
146		441
147	You can additionall set a timeout to occur on the watcher, but note that
148	this timeout will not be reset when you get an I/O event in the EV::PERSIST
149	case, and reaching a timeout will always stop the watcher even in the
150	EV::PERSIST case.
151
152	If you want a timeout to occur only after a specific time of inactivity, set
153	a repeating timeout and do NOT use EV::PERSIST.
154
155	Eventmask can be one or more of these constants ORed together:	442	The $eventmask can be one or more of these constants ORed together:
156		443
157	EV::READ wait until read() wouldn't block anymore	444	EV::READ wait until read() wouldn't block anymore
158	EV::WRITE wait until write() wouldn't block anymore	445	EV::WRITE wait until write() wouldn't block anymore
159	EV::PERSIST stay active after a (non-timeout) event occured
160		446
161	The C<io_ns> variant doesn't add/start the newly created watcher.	447	The C<io_ns> variant doesn't start (activate) the newly created watcher.
162		448
163	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	449	=item $w->set ($fileno_or_fh, $eventmask)
164		450
165	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	451	Reconfigures the watcher, see the constructor above for details. Can be
		452	called at any time.
166		453
167	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	454	=item $current_fh = $w->fh
168	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
169	and will automatically be cleared. The watcher will be restarted after each event.
170		455
171	If the timeout is zero or undef, no timeout will be set, and a normal	456	=item $old_fh = $w->fh ($new_fh)
172	watcher (with the persist flag set!) will be created.
173		457
174	This has the effect of timing out after the specified period of inactivity	458	Returns the previously set filehandle and optionally set a new one.
175	has happened.
176		459
177	Due to the design of libevent, this is also relatively inefficient, having	460	=item $current_eventmask = $w->events
178	one or two io watchers and a separate timeout watcher that you reset on
179	activity (by calling its C<start> method) is usually more efficient.
180		461
		462	=item $old_eventmask = $w->events ($new_eventmask)
		463
		464	Returns the previously set event mask and optionally set a new one.
		465
		466	=back
		467
		468
		469	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		470
		471	=over 4
		472
181	=item my $w = EV::timer $after, $repeat, $callback	473	=item $w = EV::timer $after, $repeat, $callback
182		474
183	=item my $w = EV::timer_ns $after, $repeat, $callback	475	=item $w = EV::timer_ns $after, $repeat, $callback
184		476
185	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	477	=item $w = $loop->timer ($after, $repeat, $callback)
186	timer will be restarted after the callback returns. This means that the
187	callback would be called roughly every C<$after> seconds, prolonged by the
188	time the callback takes.
189		478
		479	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		480
		481	Calls the callback after C<$after> seconds (which may be fractional). If
		482	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		483	value as $after) after the callback returns.
		484
		485	This means that the callback would be called roughly after C<$after>
		486	seconds, and then every C<$repeat> seconds. The timer does his best not
		487	to drift, but it will not invoke the timer more often then once per event
		488	loop iteration, and might drift in other cases. If that isn't acceptable,
		489	look at EV::periodic, which can provide long-term stable timers.
		490
		491	The timer is based on a monotonic clock, that is, if somebody is sitting
		492	in front of the machine while the timer is running and changes the system
		493	clock, the timer will nevertheless run (roughly) the same time.
		494
190	The C<timer_ns> variant doesn't add/start the newly created watcher.	495	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
191		496
192	=item my $w = EV::timer_abs $at, $interval, $callback	497	=item $w->set ($after, $repeat)
193		498
194	=item my $w = EV::timer_abs_ns $at, $interval, $callback	499	Reconfigures the watcher, see the constructor above for details. Can be called at
		500	any time.
195		501
196	Similar to EV::timer, but the time is given as an absolute point in time	502	=item $w->again
197	(C<$at>), plus an optional C<$interval>.
198		503
199	If the C<$interval> is zero, then the callback will be called at the time	504	Similar to the C<start> method, but has special semantics for repeating timers:
200	C<$at> if that is in the future, or as soon as possible if its in the
201	past. It will not automatically repeat.
202		505
203	If the C<$interval> is nonzero, then the watcher will always be scheduled	506	If the timer is active and non-repeating, it will be stopped.
204	to time out at the next C<$at + integer * $interval> time.
205		507
206	This can be used to schedule a callback to run at very regular intervals,	508	If the timer is active and repeating, reset the timeout to occur
207	as long as the processing time is less then the interval (otherwise	509	C<$repeat> seconds after now.
208	obviously events will be skipped).	510
		511	If the timer is inactive and repeating, start it using the repeat value.
		512
		513	Otherwise do nothing.
		514
		515	This behaviour is useful when you have a timeout for some IO
		516	operation. You create a timer object with the same value for C<$after> and
		517	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		518	on the timeout.
		519
		520	=back
		521
		522
		523	=head3 PERIODIC WATCHERS - to cron or not to cron?
		524
		525	=over 4
		526
		527	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		528
		529	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		530
		531	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		532
		533	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		534
		535	Similar to EV::timer, but is not based on relative timeouts but on
		536	absolute times. Apart from creating "simple" timers that trigger "at" the
		537	specified time, it can also be used for non-drifting absolute timers and
		538	more complex, cron-like, setups that are not adversely affected by time
		539	jumps (i.e. when the system clock is changed by explicit date -s or other
		540	means such as ntpd). It is also the most complex watcher type in EV.
		541
		542	It has three distinct "modes":
		543
		544	=over 4
		545
		546	=item * absolute timer ($interval = $reschedule_cb = 0)
		547
		548	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		549	will not adjust when a time jump occurs, that is, if it is to be run
		550	at January 1st 2011 then it will run when the system time reaches or
		551	surpasses this time.
		552
		553	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		554
		555	In this mode the watcher will always be scheduled to time out at the
		556	next C<$at + N * $interval> time (for some integer N) and then repeat,
		557	regardless of any time jumps.
		558
		559	This can be used to create timers that do not drift with respect to system
		560	time:
		561
		562	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		563
		564	That doesn't mean there will always be 3600 seconds in between triggers,
		565	but only that the the clalback will be called when the system time shows a
		566	full hour (UTC).
209		567
210	Another way to think about it (for the mathematically inclined) is that	568	Another way to think about it (for the mathematically inclined) is that
211	C<timer_abs> will try to tun the callback at the next possible time where	569	EV::periodic will try to run the callback in this mode at the next
212	C<$time = $at (mod $interval)>, regardless of any time jumps.	570	possible time where C<$time = $at (mod $interval)>, regardless of any time
		571	jumps.
213		572
		573	=item * manual reschedule mode ($reschedule_cb = coderef)
		574
		575	In this mode $interval and $at are both being ignored. Instead, each
		576	time the periodic watcher gets scheduled, the reschedule callback
		577	($reschedule_cb) will be called with the watcher as first, and the current
		578	time as second argument.
		579
		580	I<This callback MUST NOT stop or destroy this or any other periodic
		581	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		582	you need to stop it, return 1e30 and stop it afterwards. You may create
		583	and start a C<EV::prepare> watcher for this task.
		584
		585	It must return the next time to trigger, based on the passed time value
		586	(that is, the lowest time value larger than or equal to to the second
		587	argument). It will usually be called just before the callback will be
		588	triggered, but might be called at other times, too.
		589
		590	This can be used to create very complex timers, such as a timer that
		591	triggers on each midnight, local time (actually 24 hours after the last
		592	midnight, to keep the example simple. If you know a way to do it correctly
		593	in about the same space (without requiring elaborate modules), drop me a
		594	note :):
		595
		596	my $daily = EV::periodic 0, 0, sub {
		597	my ($w, $now) = @_;
		598
		599	use Time::Local ();
		600	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		601	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		602	}, sub {
		603	print "it's midnight or likely shortly after, now\n";
		604	};
		605
		606	=back
		607
214	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	608	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
215		609
		610	=item $w->set ($at, $interval, $reschedule_cb)
		611
		612	Reconfigures the watcher, see the constructor above for details. Can be called at
		613	any time.
		614
		615	=item $w->again
		616
		617	Simply stops and starts the watcher again.
		618
		619	=item $time = $w->at
		620
		621	Return the time that the watcher is expected to trigger next.
		622
		623	=back
		624
		625
		626	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		627
		628	=over 4
		629
216	=item my $w = EV::signal $signal, $callback	630	=item $w = EV::signal $signal, $callback
217		631
218	=item my $w = EV::signal_ns $signal, $callback	632	=item $w = EV::signal_ns $signal, $callback
219		633
220	Call the callback when $signal is received (the signal can be specified	634	Call the callback when $signal is received (the signal can be specified by
221	by number or by name, just as with kill or %SIG). Signal watchers are	635	number or by name, just as with C<kill> or C<%SIG>).
222	persistent no natter what.
223		636
224	EV will grab the signal for the process (the kernel only allows one	637	EV will grab the signal for the process (the kernel only allows one
225	component to receive signals) when you start a signal watcher, and	638	component to receive a signal at a time) when you start a signal watcher,
226	removes it again when you stop it. Pelr does the same when you add/remove	639	and removes it again when you stop it. Perl does the same when you
227	callbacks to %SIG, so watch out.	640	add/remove callbacks to C<%SIG>, so watch out.
228		641
229	Unfortunately, only one handler can be registered per signal. Screw	642	You can have as many signal watchers per signal as you want.
230	libevent.
231		643
232	The C<signal_ns> variant doesn't add/start the newly created watcher.	644	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
233		645
234	=back	646	=item $w->set ($signal)
235		647
236	=head1 THE EV::Event CLASS	648	Reconfigures the watcher, see the constructor above for details. Can be
		649	called at any time.
237		650
238	All EV functions creating an event watcher (designated by C<my $w =>
239	above) support the following methods on the returned watcher object:
240
241	=over 4
242
243	=item $w->add ($timeout)
244
245	Stops and (re-)starts the event watcher, setting the optional timeout to
246	the given value, or clearing the timeout if none is given.
247
248	=item $w->start
249
250	Stops and (re-)starts the event watcher without touching the timeout.
251
252	=item $w->del
253
254	=item $w->stop
255
256	Stop the event watcher if it was started.
257
258	=item $current_callback = $w->cb
259
260	=item $old_callback = $w->cb ($new_callback)
261
262	Return the previously set callback and optionally set a new one.
263
264	=item $current_fh = $w->fh
265
266	=item $old_fh = $w->fh ($new_fh)
267
268	Returns the previously set filehandle and optionally set a new one (also
269	clears the EV::SIGNAL flag when setting a filehandle).
270
271	=item $current_signal = $w->signal	651	=item $current_signum = $w->signal
272		652
273	=item $old_signal = $w->signal ($new_signal)	653	=item $old_signum = $w->signal ($new_signal)
274		654
		655	Returns the previously set signal (always as a number not name) and
		656	optionally set a new one.
		657
		658	=back
		659
		660
		661	=head3 CHILD WATCHERS - watch out for process status changes
		662
		663	=over 4
		664
		665	=item $w = EV::child $pid, $trace, $callback
		666
		667	=item $w = EV::child_ns $pid, $trace, $callback
		668
		669	=item $w = $loop->child ($pid, $trace, $callback)
		670
		671	=item $w = $loop->child_ns ($pid, $trace, $callback)
		672
		673	Call the callback when a status change for pid C<$pid> (or any pid
		674	if C<$pid> is 0) has been received (a status change happens when the
		675	process terminates or is killed, or, when trace is true, additionally when
		676	it is stopped or continued). More precisely: when the process receives
		677	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		678	changed/zombie children and call the callback.
		679
		680	It is valid (and fully supported) to install a child watcher after a child
		681	has exited but before the event loop has started its next iteration (for
		682	example, first you C<fork>, then the new child process might exit, and
		683	only then do you install a child watcher in the parent for the new pid).
		684
		685	You can access both exit (or tracing) status and pid by using the
		686	C<rstatus> and C<rpid> methods on the watcher object.
		687
		688	You can have as many pid watchers per pid as you want, they will all be
		689	called.
		690
		691	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		692
		693	=item $w->set ($pid, $trace)
		694
		695	Reconfigures the watcher, see the constructor above for details. Can be called at
		696	any time.
		697
		698	=item $current_pid = $w->pid
		699
275	Returns the previously set signal number and optionally set a new one (also sets	700	Returns the previously set process id and optionally set a new one.
276	the EV::SIGNAL flag when setting a signal).
277		701
278	=item $current_eventmask = $w->events	702	=item $exit_status = $w->rstatus
279		703
280	=item $old_eventmask = $w->events ($new_eventmask)	704	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		705	in perlfunc).
281		706
		707	=item $pid = $w->rpid
		708
		709	Return the pid of the awaited child (useful when you have installed a
		710	watcher for all pids).
		711
		712	=back
		713
		714
		715	=head3 STAT WATCHERS - did the file attributes just change?
		716
		717	=over 4
		718
		719	=item $w = EV::stat $path, $interval, $callback
		720
		721	=item $w = EV::stat_ns $path, $interval, $callback
		722
		723	=item $w = $loop->stat ($path, $interval, $callback)
		724
		725	=item $w = $loop->stat_ns ($path, $interval, $callback)
		726
		727	Call the callback when a file status change has been detected on
		728	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		729	to "path does not exist" is a status change like any other.
		730
		731	The C<$interval> is a recommended polling interval for systems where
		732	OS-supported change notifications don't exist or are not supported. If
		733	you use C<0> then an unspecified default is used (which is highly
		734	recommended!), which is to be expected to be around five seconds usually.
		735
		736	This watcher type is not meant for massive numbers of stat watchers,
		737	as even with OS-supported change notifications, this can be
		738	resource-intensive.
		739
		740	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		741
		742	=item ... = $w->stat
		743
		744	This call is very similar to the perl C<stat> built-in: It stats (using
		745	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		746	well as EV's idea of the current stat values) to the values found.
		747
		748	In scalar context, a boolean is return indicating success or failure of
		749	the stat. In list context, the same 13-value list as with stat is returned
		750	(except that the blksize and blocks fields are not reliable).
		751
		752	In the case of an error, errno is set to C<ENOENT> (regardless of the
		753	actual error value) and the C<nlink> value is forced to zero (if the stat
		754	was successful then nlink is guaranteed to be non-zero).
		755
		756	See also the next two entries for more info.
		757
		758	=item ... = $w->attr
		759
		760	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		761	the values most recently detected by EV. See the next entry for more info.
		762
		763	=item ... = $w->prev
		764
		765	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		766	the previous set of values, before the change.
		767
		768	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		769	to the values found I<before> a change was detected, while C<< $w->attr >>
		770	returns the values found leading to the change detection. The difference (if any)
		771	between C<prev> and C<attr> is what triggered the callback.
		772
		773	If you did something to the filesystem object and do not want to trigger
		774	yet another change, you can call C<stat> to update EV's idea of what the
		775	current attributes are.
		776
		777	=item $w->set ($path, $interval)
		778
		779	Reconfigures the watcher, see the constructor above for details. Can be
		780	called at any time.
		781
		782	=item $current_path = $w->path
		783
		784	=item $old_path = $w->path ($new_path)
		785
282	Returns the previously set event mask and optionally set a new one.	786	Returns the previously set path and optionally set a new one.
283		787
284	=item $w->timeout ($after, $repeat)	788	=item $current_interval = $w->interval
285		789
286	Resets the timeout (see C<EV::timer> for details).	790	=item $old_interval = $w->interval ($new_interval)
287		791
288	=item $w->timeout_abs ($at, $interval)	792	Returns the previously set interval and optionally set a new one. Can be
		793	used to query the actual interval used.
289		794
290	Resets the timeout (see C<EV::timer_abs> for details).
291
292	=item $w->priority_set ($priority)
293
294	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
295
296	=back	795	=back
		796
		797
		798	=head3 IDLE WATCHERS - when you've got nothing better to do...
		799
		800	=over 4
		801
		802	=item $w = EV::idle $callback
		803
		804	=item $w = EV::idle_ns $callback
		805
		806	=item $w = $loop->idle ($callback)
		807
		808	=item $w = $loop->idle_ns ($callback)
		809
		810	Call the callback when there are no other pending watchers of the same or
		811	higher priority (excluding check, prepare and other idle watchers of the
		812	same or lower priority, of course). They are called idle watchers because
		813	when the watcher is the highest priority pending event in the process, the
		814	process is considered to be idle at that priority.
		815
		816	If you want a watcher that is only ever called when I<no> other events are
		817	outstanding you have to set the priority to C<EV::MINPRI>.
		818
		819	The process will not block as long as any idle watchers are active, and
		820	they will be called repeatedly until stopped.
		821
		822	For example, if you have idle watchers at priority C<0> and C<1>, and
		823	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		824	and the I/O watcher will always run when ready. Only when the idle watcher
		825	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		826	pending with the C<0>-priority idle watcher be invoked.
		827
		828	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		829
		830	=back
		831
		832
		833	=head3 PREPARE WATCHERS - customise your event loop!
		834
		835	=over 4
		836
		837	=item $w = EV::prepare $callback
		838
		839	=item $w = EV::prepare_ns $callback
		840
		841	=item $w = $loop->prepare ($callback)
		842
		843	=item $w = $loop->prepare_ns ($callback)
		844
		845	Call the callback just before the process would block. You can still
		846	create/modify any watchers at this point.
		847
		848	See the EV::check watcher, below, for explanations and an example.
		849
		850	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		851
		852	=back
		853
		854
		855	=head3 CHECK WATCHERS - customise your event loop even more!
		856
		857	=over 4
		858
		859	=item $w = EV::check $callback
		860
		861	=item $w = EV::check_ns $callback
		862
		863	=item $w = $loop->check ($callback)
		864
		865	=item $w = $loop->check_ns ($callback)
		866
		867	Call the callback just after the process wakes up again (after it has
		868	gathered events), but before any other callbacks have been invoked.
		869
		870	This is used to integrate other event-based software into the EV
		871	mainloop: You register a prepare callback and in there, you create io and
		872	timer watchers as required by the other software. Here is a real-world
		873	example of integrating Net::SNMP (with some details left out):
		874
		875	our @snmp_watcher;
		876
		877	our $snmp_prepare = EV::prepare sub {
		878	# do nothing unless active
		879	$dispatcher->{_event_queue_h}
		880	or return;
		881
		882	# make the dispatcher handle any outstanding stuff
		883	... not shown
		884
		885	# create an I/O watcher for each and every socket
		886	@snmp_watcher = (
		887	(map { EV::io $_, EV::READ, sub { } }
		888	keys %{ $dispatcher->{_descriptors} }),
		889
		890	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		891	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		892	0, sub { },
		893	);
		894	};
		895
		896	The callbacks are irrelevant (and are not even being called), the
		897	only purpose of those watchers is to wake up the process as soon as
		898	one of those events occurs (socket readable, or timer timed out). The
		899	corresponding EV::check watcher will then clean up:
		900
		901	our $snmp_check = EV::check sub {
		902	# destroy all watchers
		903	@snmp_watcher = ();
		904
		905	# make the dispatcher handle any new stuff
		906	... not shown
		907	};
		908
		909	The callbacks of the created watchers will not be called as the watchers
		910	are destroyed before this cna happen (remember EV::check gets called
		911	first).
		912
		913	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		914
		915	=back
		916
		917
		918	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		919
		920	Fork watchers are called when a C<fork ()> was detected. The invocation
		921	is done before the event loop blocks next and before C<check> watchers
		922	are being called, and only in the child after the fork.
		923
		924	=over 4
		925
		926	=item $w = EV::fork $callback
		927
		928	=item $w = EV::fork_ns $callback
		929
		930	=item $w = $loop->fork ($callback)
		931
		932	=item $w = $loop->fork_ns ($callback)
		933
		934	Call the callback before the event loop is resumed in the child process
		935	after a fork.
		936
		937	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		938
		939	=back
		940
		941
		942	=head3 EMBED WATCHERS - when one backend isn't enough...
		943
		944	This is a rather advanced watcher type that lets you embed one event loop
		945	into another (currently only IO events are supported in the embedded
		946	loop, other types of watchers might be handled in a delayed or incorrect
		947	fashion and must not be used).
		948
		949	See the libev documentation at
		950	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		951	for more details.
		952
		953	In short, this watcher is most useful on BSD systems without working
		954	kqueue to still be able to handle a large number of sockets:
		955
		956	my $socket_loop;
		957
		958	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		959	if (
		960	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		961	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		962	) {
		963	# use kqueue for sockets
		964	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		965	}
		966
		967	# use the default loop otherwise
		968	$socket_loop \|\|= EV::default_loop;
		969
		970	=over 4
		971
		972	=item $w = EV::embed $otherloop, $callback
		973
		974	=item $w = EV::embed_ns $otherloop, $callback
		975
		976	=item $w = $loop->embed ($otherloop, $callback)
		977
		978	=item $w = $loop->embed_ns ($otherloop, $callback)
		979
		980	Call the callback when the embedded event loop (C<$otherloop>) has any
		981	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		982	this version of EV, which means the embedded event loop will be managed
		983	automatically.
		984
		985	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		986
		987	=back
		988
		989	=head3 ASYNC WATCHERS - how to wake up another event loop
		990
		991	Async watchers are provided by EV, but have little use in perl directly, as perl
		992	neither supports threads nor direct access to signal handlers or other
		993	contexts where they could be of value.
		994
		995	It is, however, possible to use them from the XS level.
		996
		997	Please see the libev documentation for further details.
		998
		999	=over 4
		1000
		1001	=item $w = EV::async $callback
		1002
		1003	=item $w = EV::async_ns $callback
		1004
		1005	=item $w->send
		1006
		1007	=item $bool = $w->async_pending
		1008
		1009	=back
		1010
		1011
		1012	=head1 PERL SIGNALS
		1013
		1014	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1015	with EV is as the same as any other C library: Perl-signals will only be
		1016	handled when Perl runs, which means your signal handler might be invoked
		1017	only the next time an event callback is invoked.
		1018
		1019	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1020	ensure proper operations with regards to other event watchers.
		1021
		1022	If you cannot do this for whatever reason, you can also force a watcher
		1023	to be called on every event loop iteration by installing a C<EV::check>
		1024	watcher:
		1025
		1026	my $async_check = EV::check sub { };
		1027
		1028	This ensures that perl gets into control for a short time to handle any
		1029	pending signals, and also ensures (slightly) slower overall operation.
297		1030
298	=head1 THREADS	1031	=head1 THREADS
299		1032
300	Threads are not supported by this in any way. Perl pseudo-threads is evil	1033	Threads are not supported by this module in any way. Perl pseudo-threads
301	and must die.	1034	is evil stuff and must die. As soon as Perl gains real threads I will work
		1035	on thread support for it.
		1036
		1037	=head1 FORK
		1038
		1039	Most of the "improved" event delivering mechanisms of modern operating
		1040	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1041	not supported and usually destructive). Libev makes it possible to work
		1042	around this by having a function that recreates the kernel state after
		1043	fork in the child.
		1044
		1045	On non-win32 platforms, this module requires the pthread_atfork
		1046	functionality to do this automatically for you. This function is quite
		1047	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1048	negligible, because everything the function currently does is set a flag
		1049	that is checked only when the event loop gets used the next time, so when
		1050	you do fork but not use EV, the overhead is minimal.
		1051
		1052	On win32, there is no notion of fork so all this doesn't apply, of course.
302		1053
303	=cut	1054	=cut
304		1055
305	our $DIED = sub {	1056	our $DIED = sub {
306	warn "EV: error in callback (ignoring): $@";	1057	warn "EV: error in callback (ignoring): $@";
307	};	1058	};
308		1059
309	init;	1060	default_loop
310		1061	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
311	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
312		1062
313	1;	1063	1;
314		1064
315	=head1 SEE ALSO	1065	=head1 SEE ALSO
316		1066
317	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1067	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
318	L<EV::AnyEvent>.	1068	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1069	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1070	event-loop agnostic and portable event driven programming.
319		1071
320	=head1 AUTHOR	1072	=head1 AUTHOR
321		1073
322	Marc Lehmann <schmorp@schmorp.de>	1074	Marc Lehmann <schmorp@schmorp.de>
323	http://home.schmorp.de/	1075	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.19 by root, Thu Nov 1 11:43:10 2007 UTC vs. Revision 1.96 by root, Thu May 22 02:44:57 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.19 by root, Thu Nov 1 11:43:10 2007 UTC vs.
Revision 1.96 by root, Thu May 22 02:44:57 2008 UTC