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

Comparing EV/EV.pm (file contents):
Revision 1.3 by root, Fri Oct 26 17:40:31 2007 UTC vs.
Revision 1.104 by root, Thu Oct 2 12:26:25 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	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		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 "nothign 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	}	30	};
		31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
34	};	36	};
35	$w->timeout (10);	37
36		38	# CHILD/PID STATUS CHANGES
		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";
		49	};
		50
37	# MAINLOOP	51	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		55
43	=head1 DESCRIPTION	56	=head1 DESCRIPTION
44		57
45	This module provides an interface to libevent	58	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>).	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		60	below is comprehensive, one might also consult the documentation of
		61	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		62	F<perldoc EV::c_doc>) for more subtle details on watcher semantics or some
		63	discussion on the available backends, or how to force a specific backend
		64	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		65	detailed information.
		66
		67	This module is very fast and scalable. It is actually so fast that you
		68	can use it through the L<AnyEvent> module, stay portable to other event
		69	loops (if you don't rely on any watcher types not available through it)
		70	and still be faster than with any other event loop currently supported in
		71	Perl.
47		72
48	=cut	73	=cut
49		74
50	package EV;	75	package EV;
51		76
		77	no warnings;
52	use strict;	78	use strict;
53		79
54	BEGIN {	80	BEGIN {
55	our $VERSION = '0.01';	81	our $VERSION = '3.44';
56	use XSLoader;	82	use XSLoader;
57	XSLoader::load "EV", $VERSION;	83	XSLoader::load "EV", $VERSION;
58	}	84	}
59		85
60	=head1 FUNCTIONAL INTERFACE	86	@EV::IO::ISA =
		87	@EV::Timer::ISA =
		88	@EV::Periodic::ISA =
		89	@EV::Signal::ISA =
		90	@EV::Child::ISA =
		91	@EV::Stat::ISA =
		92	@EV::Idle::ISA =
		93	@EV::Prepare::ISA =
		94	@EV::Check::ISA =
		95	@EV::Embed::ISA =
		96	@EV::Fork::ISA =
		97	@EV::Async::ISA =
		98	"EV::Watcher";
61		99
62	=over 4	100	@EV::Loop::Default::ISA = "EV::Loop";
63		101
		102	=head1 EVENT LOOPS
		103
		104	EV supports multiple event loops: There is a single "default event loop"
		105	that can handle everything including signals and child watchers, and any
		106	number of "dynamic event loops" that can use different backends (with
		107	various limitations), but no child and signal watchers.
		108
		109	You do not have to do anything to create the default event loop: When
		110	the module is loaded a suitable backend is selected on the premise of
		111	selecting a working backend (which for example rules out kqueue on most
		112	BSDs). Modules should, unless they have "special needs" always use the
		113	default loop as this is fastest (perl-wise), best supported by other
		114	modules (e.g. AnyEvent or Coro) and most portable event loop.
		115
		116	For specific programs you can create additional event loops dynamically.
		117
		118	If you want to take avdantage of kqueue (which often works properly for
		119	sockets only) even though the default loop doesn't enable it, you can
		120	I<embed> a kqueue loop into the default loop: running the default loop
		121	will then also service the kqueue loop to some extent. See the example in
		122	the section about embed watchers for an example on how to achieve that.
		123
		124	=over 4
		125
		126	=item $loop = new EV::loop [$flags]
		127
		128	Create a new event loop as per the specified flags. Please refer to
		129	the C<ev_loop_new ()> function description in the libev documentation
		130	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		131	or locally-installed as F<EV::c_doc> manpage) for more info.
		132
		133	The loop will automatically be destroyed when it is no longer referenced
		134	by any watcher and the loop object goes out of scope.
		135
		136	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		137	is recommended, as only the default event loop is protected by this
		138	module. If you I<are> embedding this loop in the default loop, this is not
		139	necessary, as C<EV::embed> automatically does the right thing on fork.
		140
		141	=item $loop->loop_fork
		142
		143	Must be called after a fork in the child, before entering or continuing
		144	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		145	this function automatically, at some performance loss (refer to the libev
		146	documentation).
		147
		148	=item $loop->loop_verify
		149
		150	Calls C<ev_verify> to make internal consistency checks (for debugging
		151	libev) and abort the program if any data structures were found to be
		152	corrupted.
		153
		154	=item $loop = EV::default_loop [$flags]
		155
		156	Return the default loop (which is a singleton object). Since this module
		157	already creates the default loop with default flags, specifying flags here
		158	will not have any effect unless you destroy the default loop first, which
		159	isn't supported. So in short: don't do it, and if you break it, you get to
		160	keep the pieces.
		161
		162	=back
		163
		164
		165	=head1 BASIC INTERFACE
		166
		167	=over 4
		168
64	=item $EV::NPRI	169	=item $EV::DIED
65		170
66	How many priority levels are available.	171	Must contain a reference to a function that is called when a callback
		172	throws an exception (with $@ containing the error). The default prints an
		173	informative message and continues.
		174
		175	If this callback throws an exception it will be silently ignored.
		176
		177	=item $flags = EV::supported_backends
		178
		179	=item $flags = EV::recommended_backends
		180
		181	=item $flags = EV::embeddable_backends
		182
		183	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		184	instance of EV, the set of recommended backends (supposed to be good) for
		185	this platform and the set of embeddable backends (see EMBED WATCHERS).
		186
		187	=item EV::sleep $seconds
		188
		189	Block the process for the given number of (fractional) seconds.
		190
		191	=item $time = EV::time
		192
		193	Returns the current time in (fractional) seconds since the epoch.
67		194
68	=item $time = EV::now	195	=item $time = EV::now
69		196
70	Returns the time in (fractional) seconds since the epoch.	197	=item $time = $loop->now
71		198
72	=item $version = EV::version	199	Returns the time the last event loop iteration has been started. This
		200	is the time that (relative) timers are based on, and refering to it is
		201	usually faster then calling EV::time.
73		202
74	=item $method = EV::method	203	=item $backend = EV::backend
75		204
76	Return version string and event polling method used.	205	=item $backend = $loop->backend
77		206
78	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	207	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		208	or EV::METHOD_EPOLL).
79		209
80	=item EV::loopexit $after	210	=item EV::loop [$flags]
81		211
82	Exit any active loop or dispatch after C<$after> seconds or immediately if	212	=item $loop->loop ([$flags])
83	C<$after> is missing or zero.
84		213
85	=item EV::dispatch	214	Begin checking for events and calling callbacks. It returns when a
		215	callback calls EV::unloop.
86		216
87	Same as C<EV::loop 0>.	217	The $flags argument can be one of the following:
88		218
89	=item EV::event $callback	219	0 as above
		220	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		221	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
90		222
91	Creates a new event watcher waiting for nothing, calling the given callback.	223	=item EV::unloop [$how]
92		224
		225	=item $loop->unloop ([$how])
		226
		227	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		228	innermost call to EV::loop return.
		229
		230	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		231	fast as possible.
		232
		233	=item $count = EV::loop_count
		234
		235	=item $count = $loop->loop_count
		236
		237	Return the number of times the event loop has polled for new
		238	events. Sometiems useful as a generation counter.
		239
		240	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		241
		242	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		243
		244	This function rolls together an I/O and a timer watcher for a single
		245	one-shot event without the need for managing a watcher object.
		246
		247	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		248	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		249	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		250	you do not want to wait for some I/O event, specify C<undef> for
		251	C<$fh_or_undef> and C<0> for C<$events>).
		252
		253	If timeout is C<undef> or negative, then there will be no
		254	timeout. Otherwise a EV::timer with this value will be started.
		255
		256	When an error occurs or either the timeout or I/O watcher triggers, then
		257	the callback will be called with the received event set (in general
		258	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		259	C<EV::WRITE> and C<EV::TIMEOUT>).
		260
		261	EV::once doesn't return anything: the watchers stay active till either
		262	of them triggers, then they will be stopped and freed, and the callback
		263	invoked.
		264
		265	=item EV::feed_fd_event ($fd, $revents)
		266
		267	=item $loop->feed_fd_event ($fd, $revents)
		268
		269	Feed an event on a file descriptor into EV. EV will react to this call as
		270	if the readyness notifications specified by C<$revents> (a combination of
		271	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		272
		273	=item EV::feed_signal_event ($signal)
		274
		275	Feed a signal event into EV. EV will react to this call as if the signal
		276	specified by C<$signal> had occured.
		277
		278	=item EV::set_io_collect_interval $time
		279
		280	=item $loop->set_io_collect_interval ($time)
		281
		282	=item EV::set_timeout_collect_interval $time
		283
		284	=item $loop->set_timeout_collect_interval ($time)
		285
		286	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		287	wait interval for timer events. See the libev documentation at
		288	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		289	(locally installed as F<EV::c_doc>) for a more detailed discussion.
		290
		291	=back
		292
		293
		294	=head1 WATCHER OBJECTS
		295
		296	A watcher is an object that gets created to record your interest in some
		297	event. For instance, if you want to wait for STDIN to become readable, you
		298	would create an EV::io watcher for that:
		299
		300	my $watcher = EV::io *STDIN, EV::READ, sub {
		301	my ($watcher, $revents) = @_;
		302	warn "yeah, STDIN should now be readable without blocking!\n"
		303	};
		304
		305	All watchers can be active (waiting for events) or inactive (paused). Only
		306	active watchers will have their callbacks invoked. All callbacks will be
		307	called with at least two arguments: the watcher and a bitmask of received
		308	events.
		309
		310	Each watcher type has its associated bit in revents, so you can use the
		311	same callback for multiple watchers. The event mask is named after the
		312	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		313	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		314	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		315	uses EV::TIMEOUT).
		316
		317	In the rare case where one wants to create a watcher but not start it at
		318	the same time, each constructor has a variant with a trailing C<_ns> in
		319	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		320
		321	Please note that a watcher will automatically be stopped when the watcher
		322	object is destroyed, so you I<need> to keep the watcher objects returned by
		323	the constructors.
		324
		325	Also, all methods changing some aspect of a watcher (->set, ->priority,
		326	->fh and so on) automatically stop and start it again if it is active,
		327	which means pending events get lost.
		328
		329	=head2 COMMON WATCHER METHODS
		330
		331	This section lists methods common to all watchers.
		332
		333	=over 4
		334
		335	=item $w->start
		336
		337	Starts a watcher if it isn't active already. Does nothing to an already
		338	active watcher. By default, all watchers start out in the active state
		339	(see the description of the C<_ns> variants if you need stopped watchers).
		340
		341	=item $w->stop
		342
		343	Stop a watcher if it is active. Also clear any pending events (events that
		344	have been received but that didn't yet result in a callback invocation),
		345	regardless of whether the watcher was active or not.
		346
		347	=item $bool = $w->is_active
		348
		349	Returns true if the watcher is active, false otherwise.
		350
		351	=item $current_data = $w->data
		352
		353	=item $old_data = $w->data ($new_data)
		354
		355	Queries a freely usable data scalar on the watcher and optionally changes
		356	it. This is a way to associate custom data with a watcher:
		357
		358	my $w = EV::timer 60, 0, sub {
		359	warn $_[0]->data;
		360	};
		361	$w->data ("print me!");
		362
		363	=item $current_cb = $w->cb
		364
		365	=item $old_cb = $w->cb ($new_cb)
		366
		367	Queries the callback on the watcher and optionally changes it. You can do
		368	this at any time without the watcher restarting.
		369
		370	=item $current_priority = $w->priority
		371
		372	=item $old_priority = $w->priority ($new_priority)
		373
		374	Queries the priority on the watcher and optionally changes it. Pending
		375	watchers with higher priority will be invoked first. The valid range of
		376	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		377	-2). If the priority is outside this range it will automatically be
		378	normalised to the nearest valid priority.
		379
		380	The default priority of any newly-created watcher is 0.
		381
		382	Note that the priority semantics have not yet been fleshed out and are
		383	subject to almost certain change.
		384
		385	=item $w->invoke ($revents)
		386
		387	Call the callback now with the given event mask.
		388
		389	=item $w->feed_event ($revents)
		390
		391	Feed some events on this watcher into EV. EV will react to this call as if
		392	the watcher had received the given C<$revents> mask.
		393
		394	=item $revents = $w->clear_pending
		395
		396	If the watcher is pending, this function clears its pending status and
		397	returns its C<$revents> bitset (as if its callback was invoked). If the
		398	watcher isn't pending it does nothing and returns C<0>.
		399
		400	=item $previous_state = $w->keepalive ($bool)
		401
		402	Normally, C<EV::loop> will return when there are no active watchers
		403	(which is a "deadlock" because no progress can be made anymore). This is
		404	convinient because it allows you to start your watchers (and your jobs),
		405	call C<EV::loop> once and when it returns you know that all your jobs are
		406	finished (or they forgot to register some watchers for their task :).
		407
		408	Sometimes, however, this gets in your way, for example when the module
		409	that calls C<EV::loop> (usually the main program) is not the same module
		410	as a long-living watcher (for example a DNS client module written by
		411	somebody else even). Then you might want any outstanding requests to be
		412	handled, but you would not want to keep C<EV::loop> from returning just
		413	because you happen to have this long-running UDP port watcher.
		414
		415	In this case you can clear the keepalive status, which means that even
		416	though your watcher is active, it won't keep C<EV::loop> from returning.
		417
		418	The initial value for keepalive is true (enabled), and you cna change it
		419	any time.
		420
		421	Example: Register an I/O watcher for some UDP socket but do not keep the
		422	event loop from running just because of that watcher.
		423
		424	my $udp_socket = ...
		425	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		426	$udp_watcher->keepalive (0);
		427
		428	=item $loop = $w->loop
		429
		430	Return the loop that this watcher is attached to.
		431
		432	=back
		433
		434
		435	=head1 WATCHER TYPES
		436
		437	Each of the following subsections describes a single watcher type.
		438
		439	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		440
		441	=over 4
		442
93	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	443	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
94		444
95	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	445	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		446
		447	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		448
		449	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
96		450
97	As long as the returned watcher object is alive, call the C<$callback>	451	As long as the returned watcher object is alive, call the C<$callback>
98	when the events specified in C<$eventmask> happen. Initially, the timeout	452	when at least one of events specified in C<$eventmask> occurs.
99	is disabled.
100		453
101	The C<io_ns> variant doesn't add/start the newly created watcher.
102
103	Eventmask can be one or more of these constants ORed together:	454	The $eventmask can be one or more of these constants ORed together:
104		455
105	EV::READ wait until read() wouldn't block anymore	456	EV::READ wait until read() wouldn't block anymore
106	EV::WRITE wait until write() wouldn't block anymore	457	EV::WRITE wait until write() wouldn't block anymore
107	EV::PERSIST stay active after an event occured
108		458
109	=item my $w = EV::timer $after, $repeat, $callback
110
111	=item my $w = EV::timer_ns $after, $repeat, $callback
112
113	Calls the callback after C<$after> seconds. If C<$repeat> is true, the
114	timer will be restarted after the callback returns. This means that the
115	callback would be called roughly every C<$after> seconds, prolonged by the
116	time the callback takes.
117
118	The C<timer_ns> variant doesn't add/start the newly created watcher.	459	The C<io_ns> variant doesn't start (activate) the newly created watcher.
119		460
120	=item my $w = EV::timer_abs $at, $interval, $callback	461	=item $w->set ($fileno_or_fh, $eventmask)
121		462
122	=item my $w = EV::timer_abs_ns $at, $interval, $callback	463	Reconfigures the watcher, see the constructor above for details. Can be
123		464	called at any time.
124	Similar to EV::timer, but the time is given as an absolute point in time
125	(C<$at>), plus an optional C<$interval>.
126
127	If the C<$interval> is zero, then the callback will be called at the time
128	C<$at> if that is in the future, or as soon as possible if its in the
129	past. It will not automatically repeat.
130
131	If the C<$interval> is nonzero, then the watcher will always be scheduled
132	to time out at the next C<$at + integer * $interval> time.
133
134	This can be used to schedule a callback to run at very regular intervals,
135	as long as the processing time is less then the interval (otherwise
136	obviously events will be skipped).
137
138	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.
139
140	=item my $w = EV::signal $signum, $callback
141
142	=item my $w = EV::signal_ns $signum, $callback
143
144	Call the callback when signal $signum is received.
145
146	The C<signal_ns> variant doesn't add/start the newly created watcher.
147
148	=back
149
150	=head1 THE EV::Event CLASS
151
152	All EV functions creating an event watcher (designated by C<my $w =>
153	above) support the following methods on the returned watcher object:
154
155	=over 4
156
157	=item $w->add ($timeout)
158
159	Stops and (re-)starts the event watcher, setting the optional timeout to
160	the given value, or clearing the timeout if none is given.
161
162	=item $w->start
163
164	Stops and (re-)starts the event watcher without touching the timeout.
165
166	=item $w->del
167
168	=item $w->stop
169
170	Stop the event watcher if it was started.
171
172	=item $current_callback = $w->cb
173
174	=item $old_callback = $w->cb ($new_callback)
175
176	Return the previously set callback and optionally set a new one.
177		465
178	=item $current_fh = $w->fh	466	=item $current_fh = $w->fh
179		467
180	=item $old_fh = $w->fh ($new_fh)	468	=item $old_fh = $w->fh ($new_fh)
181		469
185		473
186	=item $old_eventmask = $w->events ($new_eventmask)	474	=item $old_eventmask = $w->events ($new_eventmask)
187		475
188	Returns the previously set event mask and optionally set a new one.	476	Returns the previously set event mask and optionally set a new one.
189		477
		478	=back
		479
		480
		481	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		482
		483	=over 4
		484
		485	=item $w = EV::timer $after, $repeat, $callback
		486
		487	=item $w = EV::timer_ns $after, $repeat, $callback
		488
		489	=item $w = $loop->timer ($after, $repeat, $callback)
		490
		491	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		492
		493	Calls the callback after C<$after> seconds (which may be fractional). If
		494	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		495	value as $after) after the callback returns.
		496
		497	This means that the callback would be called roughly after C<$after>
		498	seconds, and then every C<$repeat> seconds. The timer does his best not
		499	to drift, but it will not invoke the timer more often then once per event
		500	loop iteration, and might drift in other cases. If that isn't acceptable,
		501	look at EV::periodic, which can provide long-term stable timers.
		502
		503	The timer is based on a monotonic clock, that is, if somebody is sitting
		504	in front of the machine while the timer is running and changes the system
		505	clock, the timer will nevertheless run (roughly) the same time.
		506
		507	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		508
190	=item $w->timeout ($after, $repeat)	509	=item $w->set ($after, $repeat)
191		510
192	Resets the timeout (see C<EV::timer> for details).	511	Reconfigures the watcher, see the constructor above for details. Can be called at
		512	any time.
193		513
		514	=item $w->again
		515
		516	Similar to the C<start> method, but has special semantics for repeating timers:
		517
		518	If the timer is active and non-repeating, it will be stopped.
		519
		520	If the timer is active and repeating, reset the timeout to occur
		521	C<$repeat> seconds after now.
		522
		523	If the timer is inactive and repeating, start it using the repeat value.
		524
		525	Otherwise do nothing.
		526
		527	This behaviour is useful when you have a timeout for some IO
		528	operation. You create a timer object with the same value for C<$after> and
		529	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		530	on the timeout.
		531
		532	=back
		533
		534
		535	=head3 PERIODIC WATCHERS - to cron or not to cron?
		536
		537	=over 4
		538
		539	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		540
		541	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		542
		543	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		544
		545	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		546
		547	Similar to EV::timer, but is not based on relative timeouts but on
		548	absolute times. Apart from creating "simple" timers that trigger "at" the
		549	specified time, it can also be used for non-drifting absolute timers and
		550	more complex, cron-like, setups that are not adversely affected by time
		551	jumps (i.e. when the system clock is changed by explicit date -s or other
		552	means such as ntpd). It is also the most complex watcher type in EV.
		553
		554	It has three distinct "modes":
		555
		556	=over 4
		557
		558	=item * absolute timer ($interval = $reschedule_cb = 0)
		559
		560	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		561	will not adjust when a time jump occurs, that is, if it is to be run
		562	at January 1st 2011 then it will run when the system time reaches or
		563	surpasses this time.
		564
		565	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		566
		567	In this mode the watcher will always be scheduled to time out at the
		568	next C<$at + N * $interval> time (for some integer N) and then repeat,
		569	regardless of any time jumps.
		570
		571	This can be used to create timers that do not drift with respect to system
		572	time:
		573
		574	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		575
		576	That doesn't mean there will always be 3600 seconds in between triggers,
		577	but only that the the clalback will be called when the system time shows a
		578	full hour (UTC).
		579
		580	Another way to think about it (for the mathematically inclined) is that
		581	EV::periodic will try to run the callback in this mode at the next
		582	possible time where C<$time = $at (mod $interval)>, regardless of any time
		583	jumps.
		584
		585	=item * manual reschedule mode ($reschedule_cb = coderef)
		586
		587	In this mode $interval and $at are both being ignored. Instead, each
		588	time the periodic watcher gets scheduled, the reschedule callback
		589	($reschedule_cb) will be called with the watcher as first, and the current
		590	time as second argument.
		591
		592	I<This callback MUST NOT stop or destroy this or any other periodic
		593	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		594	you need to stop it, return 1e30 and stop it afterwards. You may create
		595	and start a C<EV::prepare> watcher for this task.
		596
		597	It must return the next time to trigger, based on the passed time value
		598	(that is, the lowest time value larger than or equal to to the second
		599	argument). It will usually be called just before the callback will be
		600	triggered, but might be called at other times, too.
		601
		602	This can be used to create very complex timers, such as a timer that
		603	triggers on each midnight, local time (actually 24 hours after the last
		604	midnight, to keep the example simple. If you know a way to do it correctly
		605	in about the same space (without requiring elaborate modules), drop me a
		606	note :):
		607
		608	my $daily = EV::periodic 0, 0, sub {
		609	my ($w, $now) = @_;
		610
		611	use Time::Local ();
		612	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		613	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		614	}, sub {
		615	print "it's midnight or likely shortly after, now\n";
		616	};
		617
		618	=back
		619
		620	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		621
		622	=item $w->set ($at, $interval, $reschedule_cb)
		623
		624	Reconfigures the watcher, see the constructor above for details. Can be called at
		625	any time.
		626
		627	=item $w->again
		628
		629	Simply stops and starts the watcher again.
		630
		631	=item $time = $w->at
		632
		633	Return the time that the watcher is expected to trigger next.
		634
		635	=back
		636
		637
		638	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		639
		640	=over 4
		641
		642	=item $w = EV::signal $signal, $callback
		643
		644	=item $w = EV::signal_ns $signal, $callback
		645
		646	Call the callback when $signal is received (the signal can be specified by
		647	number or by name, just as with C<kill> or C<%SIG>).
		648
		649	EV will grab the signal for the process (the kernel only allows one
		650	component to receive a signal at a time) when you start a signal watcher,
		651	and removes it again when you stop it. Perl does the same when you
		652	add/remove callbacks to C<%SIG>, so watch out.
		653
		654	You can have as many signal watchers per signal as you want.
		655
		656	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		657
		658	=item $w->set ($signal)
		659
		660	Reconfigures the watcher, see the constructor above for details. Can be
		661	called at any time.
		662
		663	=item $current_signum = $w->signal
		664
		665	=item $old_signum = $w->signal ($new_signal)
		666
		667	Returns the previously set signal (always as a number not name) and
		668	optionally set a new one.
		669
		670	=back
		671
		672
		673	=head3 CHILD WATCHERS - watch out for process status changes
		674
		675	=over 4
		676
		677	=item $w = EV::child $pid, $trace, $callback
		678
		679	=item $w = EV::child_ns $pid, $trace, $callback
		680
		681	=item $w = $loop->child ($pid, $trace, $callback)
		682
		683	=item $w = $loop->child_ns ($pid, $trace, $callback)
		684
		685	Call the callback when a status change for pid C<$pid> (or any pid
		686	if C<$pid> is 0) has been received (a status change happens when the
		687	process terminates or is killed, or, when trace is true, additionally when
		688	it is stopped or continued). More precisely: when the process receives
		689	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		690	changed/zombie children and call the callback.
		691
		692	It is valid (and fully supported) to install a child watcher after a child
		693	has exited but before the event loop has started its next iteration (for
		694	example, first you C<fork>, then the new child process might exit, and
		695	only then do you install a child watcher in the parent for the new pid).
		696
		697	You can access both exit (or tracing) status and pid by using the
		698	C<rstatus> and C<rpid> methods on the watcher object.
		699
		700	You can have as many pid watchers per pid as you want, they will all be
		701	called.
		702
		703	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		704
		705	=item $w->set ($pid, $trace)
		706
		707	Reconfigures the watcher, see the constructor above for details. Can be called at
		708	any time.
		709
		710	=item $current_pid = $w->pid
		711
		712	Returns the previously set process id and optionally set a new one.
		713
		714	=item $exit_status = $w->rstatus
		715
		716	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		717	in perlfunc).
		718
		719	=item $pid = $w->rpid
		720
		721	Return the pid of the awaited child (useful when you have installed a
		722	watcher for all pids).
		723
		724	=back
		725
		726
		727	=head3 STAT WATCHERS - did the file attributes just change?
		728
		729	=over 4
		730
		731	=item $w = EV::stat $path, $interval, $callback
		732
		733	=item $w = EV::stat_ns $path, $interval, $callback
		734
		735	=item $w = $loop->stat ($path, $interval, $callback)
		736
		737	=item $w = $loop->stat_ns ($path, $interval, $callback)
		738
		739	Call the callback when a file status change has been detected on
		740	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		741	to "path does not exist" is a status change like any other.
		742
		743	The C<$interval> is a recommended polling interval for systems where
		744	OS-supported change notifications don't exist or are not supported. If
		745	you use C<0> then an unspecified default is used (which is highly
		746	recommended!), which is to be expected to be around five seconds usually.
		747
		748	This watcher type is not meant for massive numbers of stat watchers,
		749	as even with OS-supported change notifications, this can be
		750	resource-intensive.
		751
		752	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		753
		754	=item ... = $w->stat
		755
		756	This call is very similar to the perl C<stat> built-in: It stats (using
		757	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		758	well as EV's idea of the current stat values) to the values found.
		759
		760	In scalar context, a boolean is return indicating success or failure of
		761	the stat. In list context, the same 13-value list as with stat is returned
		762	(except that the blksize and blocks fields are not reliable).
		763
		764	In the case of an error, errno is set to C<ENOENT> (regardless of the
		765	actual error value) and the C<nlink> value is forced to zero (if the stat
		766	was successful then nlink is guaranteed to be non-zero).
		767
		768	See also the next two entries for more info.
		769
		770	=item ... = $w->attr
		771
		772	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		773	the values most recently detected by EV. See the next entry for more info.
		774
		775	=item ... = $w->prev
		776
		777	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		778	the previous set of values, before the change.
		779
		780	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		781	to the values found I<before> a change was detected, while C<< $w->attr >>
		782	returns the values found leading to the change detection. The difference (if any)
		783	between C<prev> and C<attr> is what triggered the callback.
		784
		785	If you did something to the filesystem object and do not want to trigger
		786	yet another change, you can call C<stat> to update EV's idea of what the
		787	current attributes are.
		788
194	=item $w->timeout_abs ($at, $interval)	789	=item $w->set ($path, $interval)
195		790
196	Resets the timeout (see C<EV::timer_abs> for details).	791	Reconfigures the watcher, see the constructor above for details. Can be
		792	called at any time.
197		793
198	=item $w->priority_set ($priority)	794	=item $current_path = $w->path
199		795
200	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	796	=item $old_path = $w->path ($new_path)
201		797
202	=back	798	Returns the previously set path and optionally set a new one.
203		799
204	=head1 BUGS	800	=item $current_interval = $w->interval
205		801
206	Lots. Libevent itself isn't well tested and rather buggy, and this module	802	=item $old_interval = $w->interval ($new_interval)
207	is quite new at the moment.	803
		804	Returns the previously set interval and optionally set a new one. Can be
		805	used to query the actual interval used.
		806
		807	=back
		808
		809
		810	=head3 IDLE WATCHERS - when you've got nothing better to do...
		811
		812	=over 4
		813
		814	=item $w = EV::idle $callback
		815
		816	=item $w = EV::idle_ns $callback
		817
		818	=item $w = $loop->idle ($callback)
		819
		820	=item $w = $loop->idle_ns ($callback)
		821
		822	Call the callback when there are no other pending watchers of the same or
		823	higher priority (excluding check, prepare and other idle watchers of the
		824	same or lower priority, of course). They are called idle watchers because
		825	when the watcher is the highest priority pending event in the process, the
		826	process is considered to be idle at that priority.
		827
		828	If you want a watcher that is only ever called when I<no> other events are
		829	outstanding you have to set the priority to C<EV::MINPRI>.
		830
		831	The process will not block as long as any idle watchers are active, and
		832	they will be called repeatedly until stopped.
		833
		834	For example, if you have idle watchers at priority C<0> and C<1>, and
		835	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		836	and the I/O watcher will always run when ready. Only when the idle watcher
		837	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		838	pending with the C<0>-priority idle watcher be invoked.
		839
		840	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		841
		842	=back
		843
		844
		845	=head3 PREPARE WATCHERS - customise your event loop!
		846
		847	=over 4
		848
		849	=item $w = EV::prepare $callback
		850
		851	=item $w = EV::prepare_ns $callback
		852
		853	=item $w = $loop->prepare ($callback)
		854
		855	=item $w = $loop->prepare_ns ($callback)
		856
		857	Call the callback just before the process would block. You can still
		858	create/modify any watchers at this point.
		859
		860	See the EV::check watcher, below, for explanations and an example.
		861
		862	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		863
		864	=back
		865
		866
		867	=head3 CHECK WATCHERS - customise your event loop even more!
		868
		869	=over 4
		870
		871	=item $w = EV::check $callback
		872
		873	=item $w = EV::check_ns $callback
		874
		875	=item $w = $loop->check ($callback)
		876
		877	=item $w = $loop->check_ns ($callback)
		878
		879	Call the callback just after the process wakes up again (after it has
		880	gathered events), but before any other callbacks have been invoked.
		881
		882	This is used to integrate other event-based software into the EV
		883	mainloop: You register a prepare callback and in there, you create io and
		884	timer watchers as required by the other software. Here is a real-world
		885	example of integrating Net::SNMP (with some details left out):
		886
		887	our @snmp_watcher;
		888
		889	our $snmp_prepare = EV::prepare sub {
		890	# do nothing unless active
		891	$dispatcher->{_event_queue_h}
		892	or return;
		893
		894	# make the dispatcher handle any outstanding stuff
		895	... not shown
		896
		897	# create an I/O watcher for each and every socket
		898	@snmp_watcher = (
		899	(map { EV::io $_, EV::READ, sub { } }
		900	keys %{ $dispatcher->{_descriptors} }),
		901
		902	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		903	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		904	0, sub { },
		905	);
		906	};
		907
		908	The callbacks are irrelevant (and are not even being called), the
		909	only purpose of those watchers is to wake up the process as soon as
		910	one of those events occurs (socket readable, or timer timed out). The
		911	corresponding EV::check watcher will then clean up:
		912
		913	our $snmp_check = EV::check sub {
		914	# destroy all watchers
		915	@snmp_watcher = ();
		916
		917	# make the dispatcher handle any new stuff
		918	... not shown
		919	};
		920
		921	The callbacks of the created watchers will not be called as the watchers
		922	are destroyed before this cna happen (remember EV::check gets called
		923	first).
		924
		925	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		926
		927	=back
		928
		929
		930	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		931
		932	Fork watchers are called when a C<fork ()> was detected. The invocation
		933	is done before the event loop blocks next and before C<check> watchers
		934	are being called, and only in the child after the fork.
		935
		936	=over 4
		937
		938	=item $w = EV::fork $callback
		939
		940	=item $w = EV::fork_ns $callback
		941
		942	=item $w = $loop->fork ($callback)
		943
		944	=item $w = $loop->fork_ns ($callback)
		945
		946	Call the callback before the event loop is resumed in the child process
		947	after a fork.
		948
		949	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		950
		951	=back
		952
		953
		954	=head3 EMBED WATCHERS - when one backend isn't enough...
		955
		956	This is a rather advanced watcher type that lets you embed one event loop
		957	into another (currently only IO events are supported in the embedded
		958	loop, other types of watchers might be handled in a delayed or incorrect
		959	fashion and must not be used).
		960
		961	See the libev documentation at
		962	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		963	(locally installed as F<EV::c_doc>) for more details.
		964
		965	In short, this watcher is most useful on BSD systems without working
		966	kqueue to still be able to handle a large number of sockets:
		967
		968	my $socket_loop;
		969
		970	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		971	if (
		972	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		973	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		974	) {
		975	# use kqueue for sockets
		976	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		977	}
		978
		979	# use the default loop otherwise
		980	$socket_loop \|\|= EV::default_loop;
		981
		982	=over 4
		983
		984	=item $w = EV::embed $otherloop[, $callback]
		985
		986	=item $w = EV::embed_ns $otherloop[, $callback]
		987
		988	=item $w = $loop->embed ($otherloop[, $callback])
		989
		990	=item $w = $loop->embed_ns ($otherloop[, $callback])
		991
		992	Call the callback when the embedded event loop (C<$otherloop>) has any
		993	I/O activity. The C<$callback> is optional: if it is missing, then the
		994	embedded event loop will be managed automatically (which is recommended),
		995	otherwise you have to invoke C<sweep> yourself.
		996
		997	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		998
		999	=back
		1000
		1001	=head3 ASYNC WATCHERS - how to wake up another event loop
		1002
		1003	Async watchers are provided by EV, but have little use in perl directly, as perl
		1004	neither supports threads nor direct access to signal handlers or other
		1005	contexts where they could be of value.
		1006
		1007	It is, however, possible to use them from the XS level.
		1008
		1009	Please see the libev documentation for further details.
		1010
		1011	=over 4
		1012
		1013	=item $w = EV::async $callback
		1014
		1015	=item $w = EV::async_ns $callback
		1016
		1017	=item $w->send
		1018
		1019	=item $bool = $w->async_pending
		1020
		1021	=back
		1022
		1023
		1024	=head1 PERL SIGNALS
		1025
		1026	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1027	with EV is as the same as any other C library: Perl-signals will only be
		1028	handled when Perl runs, which means your signal handler might be invoked
		1029	only the next time an event callback is invoked.
		1030
		1031	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1032	ensure proper operations with regards to other event watchers.
		1033
		1034	If you cannot do this for whatever reason, you can also force a watcher
		1035	to be called on every event loop iteration by installing a C<EV::check>
		1036	watcher:
		1037
		1038	my $async_check = EV::check sub { };
		1039
		1040	This ensures that perl gets into control for a short time to handle any
		1041	pending signals, and also ensures (slightly) slower overall operation.
		1042
		1043	=head1 THREADS
		1044
		1045	Threads are not supported by this module in any way. Perl pseudo-threads
		1046	is evil stuff and must die. As soon as Perl gains real threads I will work
		1047	on thread support for it.
		1048
		1049	=head1 FORK
		1050
		1051	Most of the "improved" event delivering mechanisms of modern operating
		1052	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1053	not supported and usually destructive). Libev makes it possible to work
		1054	around this by having a function that recreates the kernel state after
		1055	fork in the child.
		1056
		1057	On non-win32 platforms, this module requires the pthread_atfork
		1058	functionality to do this automatically for you. This function is quite
		1059	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1060	negligible, because everything the function currently does is set a flag
		1061	that is checked only when the event loop gets used the next time, so when
		1062	you do fork but not use EV, the overhead is minimal.
		1063
		1064	On win32, there is no notion of fork so all this doesn't apply, of course.
208		1065
209	=cut	1066	=cut
210		1067
211	our $NPRI = 4;	1068	our $DIED = sub {
212	our $BASE = init;	1069	warn "EV: error in callback (ignoring): $@";
213	priority_init $NPRI;	1070	};
		1071
		1072	default_loop
		1073	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
214		1074
215	1;	1075	1;
216		1076
217	=head1 SEE ALSO	1077	=head1 SEE ALSO
218		1078
219	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1079	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
		1080	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1081	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1082	event-loop agnostic and portable event driven programming.
220		1083
221	=head1 AUTHOR	1084	=head1 AUTHOR
222		1085
223	Marc Lehmann <schmorp@schmorp.de>	1086	Marc Lehmann <schmorp@schmorp.de>
224	http://home.schmorp.de/	1087	http://home.schmorp.de/
225		1088
226	=cut	1089	=cut
227		1090

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Comparing EV/EV.pm (file contents): Revision 1.3 by root, Fri Oct 26 17:40:31 2007 UTC vs. Revision 1.104 by root, Thu Oct 2 12:26:25 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.3 by root, Fri Oct 26 17:40:31 2007 UTC vs.
Revision 1.104 by root, Thu Oct 2 12:26:25 2008 UTC