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

Comparing EV/EV.pm (file contents):
Revision 1.14 by root, Wed Oct 31 10:53:53 2007 UTC vs.
Revision 1.88 by root, Wed Apr 16 17:08:29 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, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothing received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};
35	$w->timeout (10);
36
37	my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
38	my ($w, $events) = @_;
39	if ($_[1] & EV::TIMEOUT) {
40	warn "nothing entered within 30 seconds, bye bye.\n";
41	$w->stop;
42	} else {
43	my $line = <STDIN>;
44	warn "you entered something, you again have 30 seconds.\n";
45	}
46	};	30	};
47		31
48	# SIGNALS	32	# SIGNALS
49		33
50	my $w = EV::signal 'QUIT', sub {	34	my $w = EV::signal 'QUIT', sub {
51	warn "sigquit received\n";	35	warn "sigquit received\n";
52	};	36	};
53		37
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;
		43	};
		44
		45	# STAT CHANGES
		46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
56	};	49	};
57		50
58	# MAINLOOP	51	# MAINLOOP
59	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
60	EV::loop; # the same thing
61	EV::loop EV::LOOP_ONCE; # block until some events could be handles	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
62	EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
63		55
64	=head1 DESCRIPTION	56	=head1 DESCRIPTION
65		57
66	This module provides an interface to libevent	58	This module provides an interface to libev
67	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
68	yourself with its documentation and source code to be able to use this	60	below is comprehensive, one might also consult the documentation of libev
69	module fully.	61	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
70		62	watcher semantics or some discussion on the available backends, or how to
71	Please note thta this module disables the libevent EPOLL method by	63	force a specific backend with C<LIBEV_FLAGS>, or just about in any case
72	default, see BUGS, below, if you need to enable it.	64	because it has much more detailed information.
73		65
74	=cut	66	=cut
75		67
76	package EV;	68	package EV;
77		69
78	use strict;	70	use strict;
79		71
80	BEGIN {	72	BEGIN {
81	our $VERSION = '0.03';	73	our $VERSION = '3.3';
82	use XSLoader;	74	use XSLoader;
83	XSLoader::load "EV", $VERSION;	75	XSLoader::load "EV", $VERSION;
84	}	76	}
85		77
		78	@EV::IO::ISA =
		79	@EV::Timer::ISA =
		80	@EV::Periodic::ISA =
		81	@EV::Signal::ISA =
		82	@EV::Child::ISA =
		83	@EV::Stat::ISA =
		84	@EV::Idle::ISA =
		85	@EV::Prepare::ISA =
		86	@EV::Check::ISA =
		87	@EV::Embed::ISA =
		88	@EV::Fork::ISA =
		89	@EV::Async::ISA =
		90	"EV::Watcher";
		91
		92	@EV::Loop::Default::ISA = "EV::Loop";
		93
		94	=head1 EVENT LOOPS
		95
		96	EV supports multiple event loops: There is a single "default event loop"
		97	that can handle everything including signals and child watchers, and any
		98	number of "dynamic event loops" that can use different backends (with
		99	various limitations), but no child and signal watchers.
		100
		101	You do not have to do anything to create the default event loop: When
		102	the module is loaded a suitable backend is selected on the premise of
		103	selecting a working backend (which for example rules out kqueue on most
		104	BSDs). Modules should, unless they have "special needs" always use the
		105	default loop as this is fastest (perl-wise), best supported by other
		106	modules (e.g. AnyEvent or Coro) and most portable event loop.
		107
		108	For specific programs you can create additional event loops dynamically.
		109
		110	=over 4
		111
		112	=item $loop = new EV::loop [$flags]
		113
		114	Create a new event loop as per the specified flags. Please refer to the
		115	C<ev_loop_new ()> function description in the libev documentation
		116	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		117	for more info.
		118
		119	The loop will automatically be destroyed when it is no longer referenced
		120	by any watcher and the loop object goes out of scope.
		121
		122	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		123	is protected by this module.
		124
		125	=item $loop->loop_fork
		126
		127	Must be called after a fork in the child, before entering or continuing
		128	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		129	this fucntion automatically, at some performance loss (refer to the libev
		130	documentation).
		131
		132	=item $loop = EV::default_loop [$flags]
		133
		134	Return the default loop (which is a singleton object).
		135
		136	=back
		137
		138
86	=head1 BASIC INTERFACE	139	=head1 BASIC INTERFACE
87		140
88	=over 4	141	=over 4
89		142
90	=item $EV::NPRI
91
92	How many priority levels are available.
93
94	=item $EV::DIED	143	=item $EV::DIED
95		144
96	Must contain a reference to a function that is called when a callback	145	Must contain a reference to a function that is called when a callback
97	throws an exception (with $@ containing thr error). The default prints an	146	throws an exception (with $@ containing the error). The default prints an
98	informative message and continues.	147	informative message and continues.
99		148
100	If this callback throws an exception it will be silently ignored.	149	If this callback throws an exception it will be silently ignored.
101		150
		151	=item $flags = EV::supported_backends
		152
		153	=item $flags = EV::recommended_backends
		154
		155	=item $flags = EV::embeddable_backends
		156
		157	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		158	instance of EV, the set of recommended backends (supposed to be good) for
		159	this platform and the set of embeddable backends (see EMBED WATCHERS).
		160
		161	=item EV::sleep $seconds
		162
		163	Block the process for the given number of (fractional) seconds.
		164
		165	=item $time = EV::time
		166
		167	Returns the current time in (fractional) seconds since the epoch.
		168
102	=item $time = EV::now	169	=item $time = EV::now
103		170
104	Returns the time in (fractional) seconds since the epoch.	171	=item $time = $loop->now
105		172
106	=item $version = EV::version	173	Returns the time the last event loop iteration has been started. This
		174	is the time that (relative) timers are based on, and refering to it is
		175	usually faster then calling EV::time.
107		176
108	=item $method = EV::method	177	=item $backend = EV::backend
109		178
110	Return version string and event polling method used.	179	=item $backend = $loop->backend
111		180
112	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	181	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		182	or EV::METHOD_EPOLL).
113		183
114	=item EV::loopexit $after	184	=item EV::loop [$flags]
115		185
116	Exit any active loop or dispatch after C<$after> seconds or immediately if	186	=item $loop->loop ([$flags])
117	C<$after> is missing or zero.
118		187
119	=item EV::dispatch	188	Begin checking for events and calling callbacks. It returns when a
		189	callback calls EV::unloop.
120		190
121	Same as C<EV::loop 0>.	191	The $flags argument can be one of the following:
122		192
123	=item EV::event $callback	193	0 as above
		194	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		195	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
124		196
125	Creates a new event watcher waiting for nothing, calling the given callback.	197	=item EV::unloop [$how]
126		198
		199	=item $loop->unloop ([$how])
		200
		201	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		202	innermost call to EV::loop return.
		203
		204	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		205	fast as possible.
		206
		207	=item $count = EV::loop_count
		208
		209	=item $count = $loop->loop_count
		210
		211	Return the number of times the event loop has polled for new
		212	events. Sometiems useful as a generation counter.
		213
		214	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		215
		216	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		217
		218	This function rolls together an I/O and a timer watcher for a single
		219	one-shot event without the need for managing a watcher object.
		220
		221	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		222	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		223	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		224	you do not want to wait for some I/O event, specify C<undef> for
		225	C<$fh_or_undef> and C<0> for C<$events>).
		226
		227	If timeout is C<undef> or negative, then there will be no
		228	timeout. Otherwise a EV::timer with this value will be started.
		229
		230	When an error occurs or either the timeout or I/O watcher triggers, then
		231	the callback will be called with the received event set (in general
		232	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		233	C<EV::WRITE> and C<EV::TIMEOUT>).
		234
		235	EV::once doesn't return anything: the watchers stay active till either
		236	of them triggers, then they will be stopped and freed, and the callback
		237	invoked.
		238
		239	=item EV::feed_fd_event ($fd, $revents)
		240
		241	=item $loop->feed_fd_event ($fd, $revents)
		242
		243	Feed an event on a file descriptor into EV. EV will react to this call as
		244	if the readyness notifications specified by C<$revents> (a combination of
		245	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		246
		247	=item EV::feed_signal_event ($signal)
		248
		249	Feed a signal event into EV. EV will react to this call as if the signal
		250	specified by C<$signal> had occured.
		251
		252	=item EV::set_io_collect_interval $time
		253
		254	=item $loop->set_io_collect_interval ($time)
		255
		256	=item EV::set_timeout_collect_interval $time
		257
		258	=item $loop->set_timeout_collect_interval ($time)
		259
		260	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		261	wait interval for timer events. See the libev documentation at
		262	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		263	a more detailed discussion.
		264
		265	=back
		266
		267
		268	=head1 WATCHER OBJECTS
		269
		270	A watcher is an object that gets created to record your interest in some
		271	event. For instance, if you want to wait for STDIN to become readable, you
		272	would create an EV::io watcher for that:
		273
		274	my $watcher = EV::io *STDIN, EV::READ, sub {
		275	my ($watcher, $revents) = @_;
		276	warn "yeah, STDIN should now be readable without blocking!\n"
		277	};
		278
		279	All watchers can be active (waiting for events) or inactive (paused). Only
		280	active watchers will have their callbacks invoked. All callbacks will be
		281	called with at least two arguments: the watcher and a bitmask of received
		282	events.
		283
		284	Each watcher type has its associated bit in revents, so you can use the
		285	same callback for multiple watchers. The event mask is named after the
		286	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		287	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		288	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		289	uses EV::TIMEOUT).
		290
		291	In the rare case where one wants to create a watcher but not start it at
		292	the same time, each constructor has a variant with a trailing C<_ns> in
		293	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		294
		295	Please note that a watcher will automatically be stopped when the watcher
		296	object is destroyed, so you I<need> to keep the watcher objects returned by
		297	the constructors.
		298
		299	Also, all methods changing some aspect of a watcher (->set, ->priority,
		300	->fh and so on) automatically stop and start it again if it is active,
		301	which means pending events get lost.
		302
		303	=head2 COMMON WATCHER METHODS
		304
		305	This section lists methods common to all watchers.
		306
		307	=over 4
		308
		309	=item $w->start
		310
		311	Starts a watcher if it isn't active already. Does nothing to an already
		312	active watcher. By default, all watchers start out in the active state
		313	(see the description of the C<_ns> variants if you need stopped watchers).
		314
		315	=item $w->stop
		316
		317	Stop a watcher if it is active. Also clear any pending events (events that
		318	have been received but that didn't yet result in a callback invocation),
		319	regardless of whether the watcher was active or not.
		320
		321	=item $bool = $w->is_active
		322
		323	Returns true if the watcher is active, false otherwise.
		324
		325	=item $current_data = $w->data
		326
		327	=item $old_data = $w->data ($new_data)
		328
		329	Queries a freely usable data scalar on the watcher and optionally changes
		330	it. This is a way to associate custom data with a watcher:
		331
		332	my $w = EV::timer 60, 0, sub {
		333	warn $_[0]->data;
		334	};
		335	$w->data ("print me!");
		336
		337	=item $current_cb = $w->cb
		338
		339	=item $old_cb = $w->cb ($new_cb)
		340
		341	Queries the callback on the watcher and optionally changes it. You can do
		342	this at any time without the watcher restarting.
		343
		344	=item $current_priority = $w->priority
		345
		346	=item $old_priority = $w->priority ($new_priority)
		347
		348	Queries the priority on the watcher and optionally changes it. Pending
		349	watchers with higher priority will be invoked first. The valid range of
		350	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		351	-2). If the priority is outside this range it will automatically be
		352	normalised to the nearest valid priority.
		353
		354	The default priority of any newly-created watcher is 0.
		355
		356	Note that the priority semantics have not yet been fleshed out and are
		357	subject to almost certain change.
		358
		359	=item $w->invoke ($revents)
		360
		361	Call the callback now with the given event mask.
		362
		363	=item $w->feed_event ($revents)
		364
		365	Feed some events on this watcher into EV. EV will react to this call as if
		366	the watcher had received the given C<$revents> mask.
		367
		368	=item $revents = $w->clear_pending
		369
		370	If the watcher is pending, this function clears its pending status and
		371	returns its C<$revents> bitset (as if its callback was invoked). If the
		372	watcher isn't pending it does nothing and returns C<0>.
		373
		374	=item $previous_state = $w->keepalive ($bool)
		375
		376	Normally, C<EV::loop> will return when there are no active watchers
		377	(which is a "deadlock" because no progress can be made anymore). This is
		378	convinient because it allows you to start your watchers (and your jobs),
		379	call C<EV::loop> once and when it returns you know that all your jobs are
		380	finished (or they forgot to register some watchers for their task :).
		381
		382	Sometimes, however, this gets in your way, for example when the module
		383	that calls C<EV::loop> (usually the main program) is not the same module
		384	as a long-living watcher (for example a DNS client module written by
		385	somebody else even). Then you might want any outstanding requests to be
		386	handled, but you would not want to keep C<EV::loop> from returning just
		387	because you happen to have this long-running UDP port watcher.
		388
		389	In this case you can clear the keepalive status, which means that even
		390	though your watcher is active, it won't keep C<EV::loop> from returning.
		391
		392	The initial value for keepalive is true (enabled), and you cna change it
		393	any time.
		394
		395	Example: Register an I/O watcher for some UDP socket but do not keep the
		396	event loop from running just because of that watcher.
		397
		398	my $udp_socket = ...
		399	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		400	$1000udp_watcher->keepalive (0);
		401
		402	=item $loop = $w->loop
		403
		404	Return the loop that this watcher is attached to.
		405
		406	=back
		407
		408
		409	=head1 WATCHER TYPES
		410
		411	Each of the following subsections describes a single watcher type.
		412
		413	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		414
		415	=over 4
		416
127	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	417	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
128		418
129	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	419	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		420
		421	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		422
		423	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
130		424
131	As long as the returned watcher object is alive, call the C<$callback>	425	As long as the returned watcher object is alive, call the C<$callback>
132	when the events specified in C<$eventmask> happen. Initially, the timeout	426	when at least one of events specified in C<$eventmask> occurs.
133	is disabled.
134		427
135	You can additionall set a timeout to occur on the watcher, but note that
136	this timeout will not be reset when you get an I/O event in the EV::PERSIST
137	case, and reaching a timeout will always stop the watcher even in the
138	EV::PERSIST case.
139
140	If you want a timeout to occur only after a specific time of inactivity, set
141	a repeating timeout and do NOT use EV::PERSIST.
142
143	Eventmask can be one or more of these constants ORed together:	428	The $eventmask can be one or more of these constants ORed together:
144		429
145	EV::READ wait until read() wouldn't block anymore	430	EV::READ wait until read() wouldn't block anymore
146	EV::WRITE wait until write() wouldn't block anymore	431	EV::WRITE wait until write() wouldn't block anymore
147	EV::PERSIST stay active after a (non-timeout) event occured
148		432
149	The C<io_ns> variant doesn't add/start the newly created watcher.	433	The C<io_ns> variant doesn't start (activate) the newly created watcher.
150		434
151	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	435	=item $w->set ($fileno_or_fh, $eventmask)
152		436
153	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	437	Reconfigures the watcher, see the constructor above for details. Can be
		438	called at any time.
154		439
155	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	440	=item $current_fh = $w->fh
156	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
157	and will automatically be cleared. The watcher will be restarted after each event.
158		441
159	If the timeout is zero or undef, no timeout will be set, and a normal	442	=item $old_fh = $w->fh ($new_fh)
160	watcher (with the persist flag set!) will be created.
161		443
162	This has the effect of timing out after the specified period of inactivity	444	Returns the previously set filehandle and optionally set a new one.
163	has happened.
164		445
165	Due to the design of libevent, this is also relatively inefficient, having	446	=item $current_eventmask = $w->events
166	one or two io watchers and a separate timeout watcher that you reset on
167	activity (by calling its C<start> method) is usually more efficient.
168		447
		448	=item $old_eventmask = $w->events ($new_eventmask)
		449
		450	Returns the previously set event mask and optionally set a new one.
		451
		452	=back
		453
		454
		455	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		456
		457	=over 4
		458
169	=item my $w = EV::timer $after, $repeat, $callback	459	=item $w = EV::timer $after, $repeat, $callback
170		460
171	=item my $w = EV::timer_ns $after, $repeat, $callback	461	=item $w = EV::timer_ns $after, $repeat, $callback
172		462
173	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	463	=item $w = $loop->timer ($after, $repeat, $callback)
174	timer will be restarted after the callback returns. This means that the
175	callback would be called roughly every C<$after> seconds, prolonged by the
176	time the callback takes.
177		464
		465	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		466
		467	Calls the callback after C<$after> seconds (which may be fractional). If
		468	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		469	value as $after) after the callback returns.
		470
		471	This means that the callback would be called roughly after C<$after>
		472	seconds, and then every C<$repeat> seconds. The timer does his best not
		473	to drift, but it will not invoke the timer more often then once per event
		474	loop iteration, and might drift in other cases. If that isn't acceptable,
		475	look at EV::periodic, which can provide long-term stable timers.
		476
		477	The timer is based on a monotonic clock, that is, if somebody is sitting
		478	in front of the machine while the timer is running and changes the system
		479	clock, the timer will nevertheless run (roughly) the same time.
		480
178	The C<timer_ns> variant doesn't add/start the newly created watcher.	481	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
179		482
180	=item my $w = EV::timer_abs $at, $interval, $callback	483	=item $w->set ($after, $repeat)
181		484
182	=item my $w = EV::timer_abs_ns $at, $interval, $callback	485	Reconfigures the watcher, see the constructor above for details. Can be called at
		486	any time.
183		487
184	Similar to EV::timer, but the time is given as an absolute point in time	488	=item $w->again
185	(C<$at>), plus an optional C<$interval>.
186		489
187	If the C<$interval> is zero, then the callback will be called at the time	490	Similar to the C<start> method, but has special semantics for repeating timers:
188	C<$at> if that is in the future, or as soon as possible if its in the
189	past. It will not automatically repeat.
190		491
191	If the C<$interval> is nonzero, then the watcher will always be scheduled	492	If the timer is active and non-repeating, it will be stopped.
192	to time out at the next C<$at + integer * $interval> time.
193		493
194	This can be used to schedule a callback to run at very regular intervals,	494	If the timer is active and repeating, reset the timeout to occur
195	as long as the processing time is less then the interval (otherwise	495	C<$repeat> seconds after now.
196	obviously events will be skipped).	496
		497	If the timer is inactive and repeating, start it using the repeat value.
		498
		499	Otherwise do nothing.
		500
		501	This behaviour is useful when you have a timeout for some IO
		502	operation. You create a timer object with the same value for C<$after> and
		503	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		504	on the timeout.
		505
		506	=back
		507
		508
		509	=head3 PERIODIC WATCHERS - to cron or not to cron?
		510
		511	=over 4
		512
		513	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		514
		515	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		516
		517	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		518
		519	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		520
		521	Similar to EV::timer, but is not based on relative timeouts but on
		522	absolute times. Apart from creating "simple" timers that trigger "at" the
		523	specified time, it can also be used for non-drifting absolute timers and
		524	more complex, cron-like, setups that are not adversely affected by time
		525	jumps (i.e. when the system clock is changed by explicit date -s or other
		526	means such as ntpd). It is also the most complex watcher type in EV.
		527
		528	It has three distinct "modes":
		529
		530	=over 4
		531
		532	=item * absolute timer ($interval = $reschedule_cb = 0)
		533
		534	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		535	will not adjust when a time jump occurs, that is, if it is to be run
		536	at January 1st 2011 then it will run when the system time reaches or
		537	surpasses this time.
		538
		539	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		540
		541	In this mode the watcher will always be scheduled to time out at the
		542	next C<$at + N * $interval> time (for some integer N) and then repeat,
		543	regardless of any time jumps.
		544
		545	This can be used to create timers that do not drift with respect to system
		546	time:
		547
		548	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		549
		550	That doesn't mean there will always be 3600 seconds in between triggers,
		551	but only that the the clalback will be called when the system time shows a
		552	full hour (UTC).
197		553
198	Another way to think about it (for the mathematically inclined) is that	554	Another way to think about it (for the mathematically inclined) is that
199	C<timer_abs> will try to tun the callback at the next possible time where	555	EV::periodic will try to run the callback in this mode at the next
200	C<$time = $at (mod $interval)>, regardless of any time jumps.	556	possible time where C<$time = $at (mod $interval)>, regardless of any time
		557	jumps.
201		558
		559	=item * manual reschedule mode ($reschedule_cb = coderef)
		560
		561	In this mode $interval and $at are both being ignored. Instead, each
		562	time the periodic watcher gets scheduled, the reschedule callback
		563	($reschedule_cb) will be called with the watcher as first, and the current
		564	time as second argument.
		565
		566	I<This callback MUST NOT stop or destroy this or any other periodic
		567	watcher, ever>. If you need to stop it, return 1e30 and stop it
		568	afterwards.
		569
		570	It must return the next time to trigger, based on the passed time value
		571	(that is, the lowest time value larger than to the second argument). It
		572	will usually be called just before the callback will be triggered, but
		573	might be called at other times, too.
		574
		575	This can be used to create very complex timers, such as a timer that
		576	triggers on each midnight, local time (actually 24 hours after the last
		577	midnight, to keep the example simple. If you know a way to do it correctly
		578	in about the same space (without requiring elaborate modules), drop me a
		579	note :):
		580
		581	my $daily = EV::periodic 0, 0, sub {
		582	my ($w, $now) = @_;
		583
		584	use Time::Local ();
		585	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		586	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		587	}, sub {
		588	print "it's midnight or likely shortly after, now\n";
		589	};
		590
		591	=back
		592
202	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	593	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
203		594
		595	=item $w->set ($at, $interval, $reschedule_cb)
		596
		597	Reconfigures the watcher, see the constructor above for details. Can be called at
		598	any time.
		599
		600	=item $w->again
		601
		602	Simply stops and starts the watcher again.
		603
		604	=item $time = $w->at
		605
		606	Return the time that the watcher is expected to trigger next.
		607
		608	=back
		609
		610
		611	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		612
		613	=over 4
		614
204	=item my $w = EV::signal $signal, $callback	615	=item $w = EV::signal $signal, $callback
205		616
206	=item my $w = EV::signal_ns $signal, $callback	617	=item $w = EV::signal_ns $signal, $callback
207		618
208	Call the callback when $signal is received (the signal can be specified	619	Call the callback when $signal is received (the signal can be specified by
209	by number or by name, just as with kill or %SIG). Signal watchers are	620	number or by name, just as with C<kill> or C<%SIG>).
210	persistent no natter what.
211		621
212	EV will grab the signal for the process (the kernel only allows one	622	EV will grab the signal for the process (the kernel only allows one
213	component to receive signals) when you start a signal watcher, and	623	component to receive a signal at a time) when you start a signal watcher,
214	removes it again when you stop it. Pelr does the same when you add/remove	624	and removes it again when you stop it. Perl does the same when you
215	callbacks to %SIG, so watch out.	625	add/remove callbacks to C<%SIG>, so watch out.
216		626
217	Unfortunately, only one handler can be registered per signal. Screw	627	You can have as many signal watchers per signal as you want.
218	libevent.
219		628
220	The C<signal_ns> variant doesn't add/start the newly created watcher.	629	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
221		630
222	=back	631	=item $w->set ($signal)
223		632
224	=head1 THE EV::Event CLASS	633	Reconfigures the watcher, see the constructor above for details. Can be
		634	called at any time.
225		635
226	All EV functions creating an event watcher (designated by C<my $w =>
227	above) support the following methods on the returned watcher object:
228
229	=over 4
230
231	=item $w->add ($timeout)
232
233	Stops and (re-)starts the event watcher, setting the optional timeout to
234	the given value, or clearing the timeout if none is given.
235
236	=item $w->start
237
238	Stops and (re-)starts the event watcher without touching the timeout.
239
240	=item $w->del
241
242	=item $w->stop
243
244	Stop the event watcher if it was started.
245
246	=item $current_callback = $w->cb
247
248	=item $old_callback = $w->cb ($new_callback)
249
250	Return the previously set callback and optionally set a new one.
251
252	=item $current_fh = $w->fh
253
254	=item $old_fh = $w->fh ($new_fh)
255
256	Returns the previously set filehandle and optionally set a new one (also
257	clears the EV::SIGNAL flag when setting a filehandle).
258
259	=item $current_signal = $w->signal	636	=item $current_signum = $w->signal
260		637
261	=item $old_signal = $w->signal ($new_signal)	638	=item $old_signum = $w->signal ($new_signal)
262		639
		640	Returns the previously set signal (always as a number not name) and
		641	optionally set a new one.
		642
		643	=back
		644
		645
		646	=head3 CHILD WATCHERS - watch out for process status changes
		647
		648	=over 4
		649
		650	=item $w = EV::child $pid, $trace, $callback
		651
		652	=item $w = EV::child_ns $pid, $trace, $callback
		653
		654	=item $w = $loop->child ($pid, $trace, $callback)
		655
		656	=item $w = $loop->child_ns ($pid, $trace, $callback)
		657
		658	Call the callback when a status change for pid C<$pid> (or any pid
		659	if C<$pid> is 0) has been received (a status change happens when the
		660	process terminates or is killed, or, when trace is true, additionally when
		661	it is stopped or continued). More precisely: when the process receives
		662	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		663	changed/zombie children and call the callback.
		664
		665	It is valid (and fully supported) to install a child watcher after a child
		666	has exited but before the event loop has started its next iteration (for
		667	example, first you C<fork>, then the new child process might exit, and
		668	only then do you install a child watcher in the parent for the new pid).
		669
		670	You can access both exit (or tracing) status and pid by using the
		671	C<rstatus> and C<rpid> methods on the watcher object.
		672
		673	You can have as many pid watchers per pid as you want, they will all be
		674	called.
		675
		676	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		677
		678	=item $w->set ($pid, $trace)
		679
		680	Reconfigures the watcher, see the constructor above for details. Can be called at
		681	any time.
		682
		683	=item $current_pid = $w->pid
		684
263	Returns the previously set signal number and optionally set a new one (also sets	685	Returns the previously set process id and optionally set a new one.
264	the EV::SIGNAL flag when setting a signal).
265		686
266	=item $current_eventmask = $w->events	687	=item $exit_status = $w->rstatus
267		688
268	=item $old_eventmask = $w->events ($new_eventmask)	689	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		690	in perlfunc).
269		691
		692	=item $pid = $w->rpid
		693
		694	Return the pid of the awaited child (useful when you have installed a
		695	watcher for all pids).
		696
		697	=back
		698
		699
		700	=head3 STAT WATCHERS - did the file attributes just change?
		701
		702	=over 4
		703
		704	=item $w = EV::stat $path, $interval, $callback
		705
		706	=item $w = EV::stat_ns $path, $interval, $callback
		707
		708	=item $w = $loop->stat ($path, $interval, $callback)
		709
		710	=item $w = $loop->stat_ns ($path, $interval, $callback)
		711
		712	Call the callback when a file status change has been detected on
		713	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		714	to "path does not exist" is a status change like any other.
		715
		716	The C<$interval> is a recommended polling interval for systems where
		717	OS-supported change notifications don't exist or are not supported. If
		718	you use C<0> then an unspecified default is used (which is highly
		719	recommended!), which is to be expected to be around five seconds usually.
		720
		721	This watcher type is not meant for massive numbers of stat watchers,
		722	as even with OS-supported change notifications, this can be
		723	resource-intensive.
		724
		725	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		726
		727	=item ... = $w->stat
		728
		729	This call is very similar to the perl C<stat> built-in: It stats (using
		730	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		731	well as EV's idea of the current stat values) to the values found.
		732
		733	In scalar context, a boolean is return indicating success or failure of
		734	the stat. In list context, the same 13-value list as with stat is returned
		735	(except that the blksize and blocks fields are not reliable).
		736
		737	In the case of an error, errno is set to C<ENOENT> (regardless of the
		738	actual error value) and the C<nlink> value is forced to zero (if the stat
		739	was successful then nlink is guaranteed to be non-zero).
		740
		741	See also the next two entries for more info.
		742
		743	=item ... = $w->attr
		744
		745	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		746	the values most recently detected by EV. See the next entry for more info.
		747
		748	=item ... = $w->prev
		749
		750	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		751	the previous set of values, before the change.
		752
		753	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		754	to the values found I<before> a change was detected, while C<< $w->attr >>
		755	returns the values found leading to the change detection. The difference (if any)
		756	between C<prev> and C<attr> is what triggered the callback.
		757
		758	If you did something to the filesystem object and do not want to trigger
		759	yet another change, you can call C<stat> to update EV's idea of what the
		760	current attributes are.
		761
		762	=item $w->set ($path, $interval)
		763
		764	Reconfigures the watcher, see the constructor above for details. Can be
		765	called at any time.
		766
		767	=item $current_path = $w->path
		768
		769	=item $old_path = $w->path ($new_path)
		770
270	Returns the previously set event mask and optionally set a new one.	771	Returns the previously set path and optionally set a new one.
271		772
272	=item $w->timeout ($after, $repeat)	773	=item $current_interval = $w->interval
273		774
274	Resets the timeout (see C<EV::timer> for details).	775	=item $old_interval = $w->interval ($new_interval)
275		776
276	=item $w->timeout_abs ($at, $interval)	777	Returns the previously set interval and optionally set a new one. Can be
		778	used to query the actual interval used.
277		779
278	Resets the timeout (see C<EV::timer_abs> for details).
279
280	=item $w->priority_set ($priority)
281
282	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
283
284	=back	780	=back
		781
		782
		783	=head3 IDLE WATCHERS - when you've got nothing better to do...
		784
		785	=over 4
		786
		787	=item $w = EV::idle $callback
		788
		789	=item $w = EV::idle_ns $callback
		790
		791	=item $w = $loop->idle ($callback)
		792
		793	=item $w = $loop->idle_ns ($callback)
		794
		795	Call the callback when there are no other pending watchers of the same or
		796	higher priority (excluding check, prepare and other idle watchers of the
		797	same or lower priority, of course). They are called idle watchers because
		798	when the watcher is the highest priority pending event in the process, the
		799	process is considered to be idle at that priority.
		800
		801	If you want a watcher that is only ever called when I<no> other events are
		802	outstanding you have to set the priority to C<EV::MINPRI>.
		803
		804	The process will not block as long as any idle watchers are active, and
		805	they will be called repeatedly until stopped.
		806
		807	For example, if you have idle watchers at priority C<0> and C<1>, and
		808	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		809	and the I/O watcher will always run when ready. Only when the idle watcher
		810	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		811	pending with the C<0>-priority idle watcher be invoked.
		812
		813	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		814
		815	=back
		816
		817
		818	=head3 PREPARE WATCHERS - customise your event loop!
		819
		820	=over 4
		821
		822	=item $w = EV::prepare $callback
		823
		824	=item $w = EV::prepare_ns $callback
		825
		826	=item $w = $loop->prepare ($callback)
		827
		828	=item $w = $loop->prepare_ns ($callback)
		829
		830	Call the callback just before the process would block. You can still
		831	create/modify any watchers at this point.
		832
		833	See the EV::check watcher, below, for explanations and an example.
		834
		835	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		836
		837	=back
		838
		839
		840	=head3 CHECK WATCHERS - customise your event loop even more!
		841
		842	=over 4
		843
		844	=item $w = EV::check $callback
		845
		846	=item $w = EV::check_ns $callback
		847
		848	=item $w = $loop->check ($callback)
		849
		850	=item $w = $loop->check_ns ($callback)
		851
		852	Call the callback just after the process wakes up again (after it has
		853	gathered events), but before any other callbacks have been invoked.
		854
		855	This is used to integrate other event-based software into the EV
		856	mainloop: You register a prepare callback and in there, you create io and
		857	timer watchers as required by the other software. Here is a real-world
		858	example of integrating Net::SNMP (with some details left out):
		859
		860	our @snmp_watcher;
		861
		862	our $snmp_prepare = EV::prepare sub {
		863	# do nothing unless active
		864	$dispatcher->{_event_queue_h}
		865	or return;
		866
		867	# make the dispatcher handle any outstanding stuff
		868	... not shown
		869
		870	# create an I/O watcher for each and every socket
		871	@snmp_watcher = (
		872	(map { EV::io $_, EV::READ, sub { } }
		873	keys %{ $dispatcher->{_descriptors} }),
		874
		875	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		876	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		877	0, sub { },
		878	);
		879	};
		880
		881	The callbacks are irrelevant (and are not even being called), the
		882	only purpose of those watchers is to wake up the process as soon as
		883	one of those events occurs (socket readable, or timer timed out). The
		884	corresponding EV::check watcher will then clean up:
		885
		886	our $snmp_check = EV::check sub {
		887	# destroy all watchers
		888	@snmp_watcher = ();
		889
		890	# make the dispatcher handle any new stuff
		891	... not shown
		892	};
		893
		894	The callbacks of the created watchers will not be called as the watchers
		895	are destroyed before this cna happen (remember EV::check gets called
		896	first).
		897
		898	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		899
		900	=back
		901
		902
		903	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		904
		905	Fork watchers are called when a C<fork ()> was detected. The invocation
		906	is done before the event loop blocks next and before C<check> watchers
		907	are being called, and only in the child after the fork.
		908
		909	=over 4
		910
		911	=item $w = EV::fork $callback
		912
		913	=item $w = EV::fork_ns $callback
		914
		915	=item $w = $loop->fork ($callback)
		916
		917	=item $w = $loop->fork_ns ($callback)
		918
		919	Call the callback before the event loop is resumed in the child process
		920	after a fork.
		921
		922	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		923
		924	=back
		925
		926
		927	=head3 EMBED WATCHERS - when one backend isn't enough...
		928
		929	This is a rather advanced watcher type that lets you embed one event loop
		930	into another (currently only IO events are supported in the embedded
		931	loop, other types of watchers might be handled in a delayed or incorrect
		932	fashion and must not be used).
		933
		934	See the libev documentation at
		935	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		936	for more details.
		937
		938	In short, this watcher is most useful on BSD systems without working
		939	kqueue to still be able to handle a large number of sockets:
		940
		941	my $socket_loop;
		942
		943	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		944	if (
		945	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		946	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		947	) {
		948	# use kqueue for sockets
		949	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		950	}
		951
		952	# use the default loop otherwise
		953	$socket_loop \|\|= EV::default_loop;
		954
		955	=over 4
		956
		957	=item $w = EV::embed $otherloop, $callback
		958
		959	=item $w = EV::embed_ns $otherloop, $callback
		960
		961	=item $w = $loop->embed ($otherloop, $callback)
		962
		963	=item $w = $loop->embed_ns ($otherloop, $callback)
		964
		965	Call the callback when the embedded event loop (C<$otherloop>) has any
		966	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		967	this version of EV, which means the embedded event loop will be managed
		968	automatically.
		969
		970	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		971
		972	=back
		973
		974	=head3 ASYNC WATCHERS - how to wake up another event loop
		975
		976	Async watchers are provided by EV, but have little use in perl directly, as perl
		977	neither supports threads nor direct access to signal handlers or other
		978	contexts where they could be of value.
		979
		980	It is, however, possible to use them from the XS level.
		981
		982	Please see the libev documentation for further details.
		983
		984	=over 4
		985
		986	=item $w = EV::async $callback
		987
		988	=item $w = EV::async_ns $callback
		989
		990	=item $w->send
		991
		992	=item $bool = $w->async_pending
		993
		994	=back
		995
		996
		997	=head1 PERL SIGNALS
		998
		999	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1000	with EV is as the same as any other C library: Perl-signals will only be
		1001	handled when Perl runs, which means your signal handler might be invoked
		1002	only the next time an event callback is invoked.
		1003
		1004	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1005	ensure proper operations with regards to other event watchers.
		1006
		1007	If you cannot do this for whatever reason, you can also force a watcher
		1008	to be called on every event loop iteration by installing a C<EV::check>
		1009	watcher:
		1010
		1011	my $async_check = EV::check sub { };
		1012
		1013	This ensures that perl gets into control for a short time to handle any
		1014	pending signals, and also ensures (slightly) slower overall operation.
285		1015
286	=head1 THREADS	1016	=head1 THREADS
287		1017
288	Threads are not supported by this in any way. Perl pseudo-threads is evil	1018	Threads are not supported by this module in any way. Perl pseudo-threads
289	and must die.	1019	is evil stuff and must die. As soon as Perl gains real threads I will work
		1020	on thread support for it.
290		1021
291	=head1 BUGS	1022	=head1 FORK
292		1023
293	Lots. Libevent itself isn't well tested and rather buggy, and this module	1024	Most of the "improved" event delivering mechanisms of modern operating
294	is quite new at the moment.	1025	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1026	not supported and usually destructive). Libev makes it possible to work
		1027	around this by having a function that recreates the kernel state after
		1028	fork in the child.
295		1029
296	Please note that the epoll method is not, in general, reliable in programs	1030	On non-win32 platforms, this module requires the pthread_atfork
297	that use fork (even if no libveent calls are being made in the forked	1031	functionality to do this automatically for you. This function is quite
298	process). If your program behaves erratically, try setting the environment	1032	buggy on most BSDs, though, so YMMV. The overhead for this is quite
299	variable C<EVENT_NOEPOLL> first when running the program.	1033	negligible, because everything the function currently does is set a flag
		1034	that is checked only when the event loop gets used the next time, so when
		1035	you do fork but not use EV, the overhead is minimal.
300		1036
301	In general, if you fork, then you can only use the EV module in one of the	1037	On win32, there is no notion of fork so all this doesn't apply, of course.
302	children.
303		1038
304	=cut	1039	=cut
305		1040
306	our $DIED = sub {	1041	our $DIED = sub {
307	warn "EV: error in callback (ignoring): $@";	1042	warn "EV: error in callback (ignoring): $@";
308	};	1043	};
309		1044
310	init;	1045	default_loop
311		1046	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
312	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
313		1047
314	1;	1048	1;
315		1049
316	=head1 SEE ALSO	1050	=head1 SEE ALSO
317		1051
318	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1052	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
319	L<EV::AnyEvent>.	1053	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1054	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP).
320		1055
321	=head1 AUTHOR	1056	=head1 AUTHOR
322		1057
323	Marc Lehmann <schmorp@schmorp.de>	1058	Marc Lehmann <schmorp@schmorp.de>
324	http://home.schmorp.de/	1059	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.14 by root, Wed Oct 31 10:53:53 2007 UTC vs. Revision 1.88 by root, Wed Apr 16 17:08:29 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.14 by root, Wed Oct 31 10:53:53 2007 UTC vs.
Revision 1.88 by root, Wed Apr 16 17:08:29 2008 UTC