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

Comparing EV/EV.pm (file contents):
Revision 1.7 by root, Sat Oct 27 14:54:20 2007 UTC vs.
Revision 1.99 by root, Tue Jul 8 09:37:37 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/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
47	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
48	module fully.	61	itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
		62	subtle details on watcher semantics or some discussion on the available
		63	backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
		64	about in any case because it has much more detailed information.
49		65
50	Please note thta this module disables the libevent EPOLL method by	66	This module is very fast and scalable. It is actually so fast that you
51	default, see BUGS, below, if you need to enable it.	67	can use it through the L<AnyEvent> module, stay portable to other event
		68	loops (if you don't rely on any watcher types not available through it)
		69	and still be faster than with any other event loop currently supported in
		70	Perl.
52		71
53	=cut	72	=cut
54		73
55	package EV;	74	package EV;
56		75
57	use strict;	76	use strict;
58		77
59	BEGIN {	78	BEGIN {
60	our $VERSION = '0.01';	79	our $VERSION = '3.42';
61	use XSLoader;	80	use XSLoader;
62	XSLoader::load "EV", $VERSION;	81	XSLoader::load "EV", $VERSION;
63	}	82	}
64		83
65	=head1 FUNCTIONAL INTERFACE	84	@EV::IO::ISA =
		85	@EV::Timer::ISA =
		86	@EV::Periodic::ISA =
		87	@EV::Signal::ISA =
		88	@EV::Child::ISA =
		89	@EV::Stat::ISA =
		90	@EV::Idle::ISA =
		91	@EV::Prepare::ISA =
		92	@EV::Check::ISA =
		93	@EV::Embed::ISA =
		94	@EV::Fork::ISA =
		95	@EV::Async::ISA =
		96	"EV::Watcher";
66		97
67	=over 4	98	@EV::Loop::Default::ISA = "EV::Loop";
68		99
		100	=head1 EVENT LOOPS
		101
		102	EV supports multiple event loops: There is a single "default event loop"
		103	that can handle everything including signals and child watchers, and any
		104	number of "dynamic event loops" that can use different backends (with
		105	various limitations), but no child and signal watchers.
		106
		107	You do not have to do anything to create the default event loop: When
		108	the module is loaded a suitable backend is selected on the premise of
		109	selecting a working backend (which for example rules out kqueue on most
		110	BSDs). Modules should, unless they have "special needs" always use the
		111	default loop as this is fastest (perl-wise), best supported by other
		112	modules (e.g. AnyEvent or Coro) and most portable event loop.
		113
		114	For specific programs you can create additional event loops dynamically.
		115
		116	If you want to take avdantage of kqueue (which often works properly for
		117	sockets only) even though the default loop doesn't enable it, you can
		118	I<embed> a kqueue loop into the default loop: running the default loop
		119	will then also service the kqueue loop to some extent. See the example in
		120	the section about embed watchers for an example on how to achieve that.
		121
		122	=over 4
		123
		124	=item $loop = new EV::loop [$flags]
		125
		126	Create a new event loop as per the specified flags. Please refer to the
		127	C<ev_loop_new ()> function description in the libev documentation
		128	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		129	for more info.
		130
		131	The loop will automatically be destroyed when it is no longer referenced
		132	by any watcher and the loop object goes out of scope.
		133
		134	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		135	is protected by this module.
		136
		137	=item $loop->loop_fork
		138
		139	Must be called after a fork in the child, before entering or continuing
		140	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		141	this function automatically, at some performance loss (refer to the libev
		142	documentation).
		143
		144	=item $loop->loop_verify
		145
		146	Calls C<ev_verify> to make internal consistency checks (for debugging
		147	libev) and abort the program if any data structures were found to be
		148	corrupted.
		149
		150	=item $loop = EV::default_loop [$flags]
		151
		152	Return the default loop (which is a singleton object). Since this module
		153	already creates the default loop with default flags, specifying flags here
		154	will not have any effect unless you destroy the default loop first, which
		155	isn't supported. So in short: don't do it, and if you break it, you get to
		156	keep the pieces.
		157
		158	=back
		159
		160
		161	=head1 BASIC INTERFACE
		162
		163	=over 4
		164
69	=item $EV::NPRI	165	=item $EV::DIED
70		166
71	How many priority levels are available.	167	Must contain a reference to a function that is called when a callback
		168	throws an exception (with $@ containing the error). The default prints an
		169	informative message and continues.
		170
		171	If this callback throws an exception it will be silently ignored.
		172
		173	=item $flags = EV::supported_backends
		174
		175	=item $flags = EV::recommended_backends
		176
		177	=item $flags = EV::embeddable_backends
		178
		179	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		180	instance of EV, the set of recommended backends (supposed to be good) for
		181	this platform and the set of embeddable backends (see EMBED WATCHERS).
		182
		183	=item EV::sleep $seconds
		184
		185	Block the process for the given number of (fractional) seconds.
		186
		187	=item $time = EV::time
		188
		189	Returns the current time in (fractional) seconds since the epoch.
72		190
73	=item $time = EV::now	191	=item $time = EV::now
74		192
75	Returns the time in (fractional) seconds since the epoch.	193	=item $time = $loop->now
76		194
77	=item $version = EV::version	195	Returns the time the last event loop iteration has been started. This
		196	is the time that (relative) timers are based on, and refering to it is
		197	usually faster then calling EV::time.
78		198
79	=item $method = EV::method	199	=item $backend = EV::backend
80		200
81	Return version string and event polling method used.	201	=item $backend = $loop->backend
82		202
83	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	203	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		204	or EV::METHOD_EPOLL).
84		205
85	=item EV::loopexit $after	206	=item EV::loop [$flags]
86		207
87	Exit any active loop or dispatch after C<$after> seconds or immediately if	208	=item $loop->loop ([$flags])
88	C<$after> is missing or zero.
89		209
90	=item EV::dispatch	210	Begin checking for events and calling callbacks. It returns when a
		211	callback calls EV::unloop.
91		212
92	Same as C<EV::loop 0>.	213	The $flags argument can be one of the following:
93		214
94	=item EV::event $callback	215	0 as above
		216	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		217	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
95		218
96	Creates a new event watcher waiting for nothing, calling the given callback.	219	=item EV::unloop [$how]
97		220
		221	=item $loop->unloop ([$how])
		222
		223	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		224	innermost call to EV::loop return.
		225
		226	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		227	fast as possible.
		228
		229	=item $count = EV::loop_count
		230
		231	=item $count = $loop->loop_count
		232
		233	Return the number of times the event loop has polled for new
		234	events. Sometiems useful as a generation counter.
		235
		236	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		237
		238	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		239
		240	This function rolls together an I/O and a timer watcher for a single
		241	one-shot event without the need for managing a watcher object.
		242
		243	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		244	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		245	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		246	you do not want to wait for some I/O event, specify C<undef> for
		247	C<$fh_or_undef> and C<0> for C<$events>).
		248
		249	If timeout is C<undef> or negative, then there will be no
		250	timeout. Otherwise a EV::timer with this value will be started.
		251
		252	When an error occurs or either the timeout or I/O watcher triggers, then
		253	the callback will be called with the received event set (in general
		254	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		255	C<EV::WRITE> and C<EV::TIMEOUT>).
		256
		257	EV::once doesn't return anything: the watchers stay active till either
		258	of them triggers, then they will be stopped and freed, and the callback
		259	invoked.
		260
		261	=item EV::feed_fd_event ($fd, $revents)
		262
		263	=item $loop->feed_fd_event ($fd, $revents)
		264
		265	Feed an event on a file descriptor into EV. EV will react to this call as
		266	if the readyness notifications specified by C<$revents> (a combination of
		267	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		268
		269	=item EV::feed_signal_event ($signal)
		270
		271	Feed a signal event into EV. EV will react to this call as if the signal
		272	specified by C<$signal> had occured.
		273
		274	=item EV::set_io_collect_interval $time
		275
		276	=item $loop->set_io_collect_interval ($time)
		277
		278	=item EV::set_timeout_collect_interval $time
		279
		280	=item $loop->set_timeout_collect_interval ($time)
		281
		282	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		283	wait interval for timer events. See the libev documentation at
		284	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		285	a more detailed discussion.
		286
		287	=back
		288
		289
		290	=head1 WATCHER OBJECTS
		291
		292	A watcher is an object that gets created to record your interest in some
		293	event. For instance, if you want to wait for STDIN to become readable, you
		294	would create an EV::io watcher for that:
		295
		296	my $watcher = EV::io *STDIN, EV::READ, sub {
		297	my ($watcher, $revents) = @_;
		298	warn "yeah, STDIN should now be readable without blocking!\n"
		299	};
		300
		301	All watchers can be active (waiting for events) or inactive (paused). Only
		302	active watchers will have their callbacks invoked. All callbacks will be
		303	called with at least two arguments: the watcher and a bitmask of received
		304	events.
		305
		306	Each watcher type has its associated bit in revents, so you can use the
		307	same callback for multiple watchers. The event mask is named after the
		308	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		309	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		310	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		311	uses EV::TIMEOUT).
		312
		313	In the rare case where one wants to create a watcher but not start it at
		314	the same time, each constructor has a variant with a trailing C<_ns> in
		315	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		316
		317	Please note that a watcher will automatically be stopped when the watcher
		318	object is destroyed, so you I<need> to keep the watcher objects returned by
		319	the constructors.
		320
		321	Also, all methods changing some aspect of a watcher (->set, ->priority,
		322	->fh and so on) automatically stop and start it again if it is active,
		323	which means pending events get lost.
		324
		325	=head2 COMMON WATCHER METHODS
		326
		327	This section lists methods common to all watchers.
		328
		329	=over 4
		330
		331	=item $w->start
		332
		333	Starts a watcher if it isn't active already. Does nothing to an already
		334	active watcher. By default, all watchers start out in the active state
		335	(see the description of the C<_ns> variants if you need stopped watchers).
		336
		337	=item $w->stop
		338
		339	Stop a watcher if it is active. Also clear any pending events (events that
		340	have been received but that didn't yet result in a callback invocation),
		341	regardless of whether the watcher was active or not.
		342
		343	=item $bool = $w->is_active
		344
		345	Returns true if the watcher is active, false otherwise.
		346
		347	=item $current_data = $w->data
		348
		349	=item $old_data = $w->data ($new_data)
		350
		351	Queries a freely usable data scalar on the watcher and optionally changes
		352	it. This is a way to associate custom data with a watcher:
		353
		354	my $w = EV::timer 60, 0, sub {
		355	warn $_[0]->data;
		356	};
		357	$w->data ("print me!");
		358
		359	=item $current_cb = $w->cb
		360
		361	=item $old_cb = $w->cb ($new_cb)
		362
		363	Queries the callback on the watcher and optionally changes it. You can do
		364	this at any time without the watcher restarting.
		365
		366	=item $current_priority = $w->priority
		367
		368	=item $old_priority = $w->priority ($new_priority)
		369
		370	Queries the priority on the watcher and optionally changes it. Pending
		371	watchers with higher priority will be invoked first. The valid range of
		372	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		373	-2). If the priority is outside this range it will automatically be
		374	normalised to the nearest valid priority.
		375
		376	The default priority of any newly-created watcher is 0.
		377
		378	Note that the priority semantics have not yet been fleshed out and are
		379	subject to almost certain change.
		380
		381	=item $w->invoke ($revents)
		382
		383	Call the callback now with the given event mask.
		384
		385	=item $w->feed_event ($revents)
		386
		387	Feed some events on this watcher into EV. EV will react to this call as if
		388	the watcher had received the given C<$revents> mask.
		389
		390	=item $revents = $w->clear_pending
		391
		392	If the watcher is pending, this function clears its pending status and
		393	returns its C<$revents> bitset (as if its callback was invoked). If the
		394	watcher isn't pending it does nothing and returns C<0>.
		395
		396	=item $previous_state = $w->keepalive ($bool)
		397
		398	Normally, C<EV::loop> will return when there are no active watchers
		399	(which is a "deadlock" because no progress can be made anymore). This is
		400	convinient because it allows you to start your watchers (and your jobs),
		401	call C<EV::loop> once and when it returns you know that all your jobs are
		402	finished (or they forgot to register some watchers for their task :).
		403
		404	Sometimes, however, this gets in your way, for example when the module
		405	that calls C<EV::loop> (usually the main program) is not the same module
		406	as a long-living watcher (for example a DNS client module written by
		407	somebody else even). Then you might want any outstanding requests to be
		408	handled, but you would not want to keep C<EV::loop> from returning just
		409	because you happen to have this long-running UDP port watcher.
		410
		411	In this case you can clear the keepalive status, which means that even
		412	though your watcher is active, it won't keep C<EV::loop> from returning.
		413
		414	The initial value for keepalive is true (enabled), and you cna change it
		415	any time.
		416
		417	Example: Register an I/O watcher for some UDP socket but do not keep the
		418	event loop from running just because of that watcher.
		419
		420	my $udp_socket = ...
		421	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		422	$udp_watcher->keepalive (0);
		423
		424	=item $loop = $w->loop
		425
		426	Return the loop that this watcher is attached to.
		427
		428	=back
		429
		430
		431	=head1 WATCHER TYPES
		432
		433	Each of the following subsections describes a single watcher type.
		434
		435	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		436
		437	=over 4
		438
98	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	439	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
99		440
100	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	441	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		442
		443	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		444
		445	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
101		446
102	As long as the returned watcher object is alive, call the C<$callback>	447	As long as the returned watcher object is alive, call the C<$callback>
103	when the events specified in C<$eventmask> happen. Initially, the timeout	448	when at least one of events specified in C<$eventmask> occurs.
104	is disabled.
105		449
106	Youc an additionall set a timeout to occur on the watcher, but note that
107	this timeout will not be reset when you get an I/O event in the EV::PERSIST
108	case, and reaching a timeout will always stop the watcher even in the
109	EV::PERSIST case.
110
111	If you want a timeout to occur only after a specific time of inactivity, set
112	a repeating timeout and do NOT use EV::PERSIST.
113
114	Eventmask can be one or more of these constants ORed together:	450	The $eventmask can be one or more of these constants ORed together:
115		451
116	EV::READ wait until read() wouldn't block anymore	452	EV::READ wait until read() wouldn't block anymore
117	EV::WRITE wait until write() wouldn't block anymore	453	EV::WRITE wait until write() wouldn't block anymore
118	EV::PERSIST stay active after a (non-timeout) event occured
119		454
120	The C<io_ns> variant doesn't add/start the newly created watcher.	455	The C<io_ns> variant doesn't start (activate) the newly created watcher.
121		456
		457	=item $w->set ($fileno_or_fh, $eventmask)
		458
		459	Reconfigures the watcher, see the constructor above for details. Can be
		460	called at any time.
		461
		462	=item $current_fh = $w->fh
		463
		464	=item $old_fh = $w->fh ($new_fh)
		465
		466	Returns the previously set filehandle and optionally set a new one.
		467
		468	=item $current_eventmask = $w->events
		469
		470	=item $old_eventmask = $w->events ($new_eventmask)
		471
		472	Returns the previously set event mask and optionally set a new one.
		473
		474	=back
		475
		476
		477	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		478
		479	=over 4
		480
122	=item my $w = EV::timer $after, $repeat, $callback	481	=item $w = EV::timer $after, $repeat, $callback
123		482
124	=item my $w = EV::timer_ns $after, $repeat, $callback	483	=item $w = EV::timer_ns $after, $repeat, $callback
125		484
126	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	485	=item $w = $loop->timer ($after, $repeat, $callback)
127	timer will be restarted after the callback returns. This means that the
128	callback would be called roughly every C<$after> seconds, prolonged by the
129	time the callback takes.
130		486
		487	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		488
		489	Calls the callback after C<$after> seconds (which may be fractional). If
		490	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		491	value as $after) after the callback returns.
		492
		493	This means that the callback would be called roughly after C<$after>
		494	seconds, and then every C<$repeat> seconds. The timer does his best not
		495	to drift, but it will not invoke the timer more often then once per event
		496	loop iteration, and might drift in other cases. If that isn't acceptable,
		497	look at EV::periodic, which can provide long-term stable timers.
		498
		499	The timer is based on a monotonic clock, that is, if somebody is sitting
		500	in front of the machine while the timer is running and changes the system
		501	clock, the timer will nevertheless run (roughly) the same time.
		502
131	The C<timer_ns> variant doesn't add/start the newly created watcher.	503	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
132		504
133	=item my $w = EV::timer_abs $at, $interval, $callback	505	=item $w->set ($after, $repeat)
134		506
135	=item my $w = EV::timer_abs_ns $at, $interval, $callback	507	Reconfigures the watcher, see the constructor above for details. Can be called at
		508	any time.
136		509
137	Similar to EV::timer, but the time is given as an absolute point in time	510	=item $w->again
138	(C<$at>), plus an optional C<$interval>.
139		511
140	If the C<$interval> is zero, then the callback will be called at the time	512	Similar to the C<start> method, but has special semantics for repeating timers:
141	C<$at> if that is in the future, or as soon as possible if its in the
142	past. It will not automatically repeat.
143		513
144	If the C<$interval> is nonzero, then the watcher will always be scheduled	514	If the timer is active and non-repeating, it will be stopped.
145	to time out at the next C<$at + integer * $interval> time.
146		515
147	This can be used to schedule a callback to run at very regular intervals,	516	If the timer is active and repeating, reset the timeout to occur
148	as long as the processing time is less then the interval (otherwise	517	C<$repeat> seconds after now.
149	obviously events will be skipped).	518
		519	If the timer is inactive and repeating, start it using the repeat value.
		520
		521	Otherwise do nothing.
		522
		523	This behaviour is useful when you have a timeout for some IO
		524	operation. You create a timer object with the same value for C<$after> and
		525	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		526	on the timeout.
		527
		528	=back
		529
		530
		531	=head3 PERIODIC WATCHERS - to cron or not to cron?
		532
		533	=over 4
		534
		535	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		536
		537	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		538
		539	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		540
		541	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		542
		543	Similar to EV::timer, but is not based on relative timeouts but on
		544	absolute times. Apart from creating "simple" timers that trigger "at" the
		545	specified time, it can also be used for non-drifting absolute timers and
		546	more complex, cron-like, setups that are not adversely affected by time
		547	jumps (i.e. when the system clock is changed by explicit date -s or other
		548	means such as ntpd). It is also the most complex watcher type in EV.
		549
		550	It has three distinct "modes":
		551
		552	=over 4
		553
		554	=item * absolute timer ($interval = $reschedule_cb = 0)
		555
		556	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		557	will not adjust when a time jump occurs, that is, if it is to be run
		558	at January 1st 2011 then it will run when the system time reaches or
		559	surpasses this time.
		560
		561	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		562
		563	In this mode the watcher will always be scheduled to time out at the
		564	next C<$at + N * $interval> time (for some integer N) and then repeat,
		565	regardless of any time jumps.
		566
		567	This can be used to create timers that do not drift with respect to system
		568	time:
		569
		570	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		571
		572	That doesn't mean there will always be 3600 seconds in between triggers,
		573	but only that the the clalback will be called when the system time shows a
		574	full hour (UTC).
150		575
151	Another way to think about it (for the mathematically inclined) is that	576	Another way to think about it (for the mathematically inclined) is that
152	C<timer_abs> will try to tun the callback at the next possible time where	577	EV::periodic will try to run the callback in this mode at the next
153	C<$time = $at (mod $interval)>, regardless of any time jumps.	578	possible time where C<$time = $at (mod $interval)>, regardless of any time
		579	jumps.
154		580
		581	=item * manual reschedule mode ($reschedule_cb = coderef)
		582
		583	In this mode $interval and $at are both being ignored. Instead, each
		584	time the periodic watcher gets scheduled, the reschedule callback
		585	($reschedule_cb) will be called with the watcher as first, and the current
		586	time as second argument.
		587
		588	I<This callback MUST NOT stop or destroy this or any other periodic
		589	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		590	you need to stop it, return 1e30 and stop it afterwards. You may create
		591	and start a C<EV::prepare> watcher for this task.
		592
		593	It must return the next time to trigger, based on the passed time value
		594	(that is, the lowest time value larger than or equal to to the second
		595	argument). It will usually be called just before the callback will be
		596	triggered, but might be called at other times, too.
		597
		598	This can be used to create very complex timers, such as a timer that
		599	triggers on each midnight, local time (actually 24 hours after the last
		600	midnight, to keep the example simple. If you know a way to do it correctly
		601	in about the same space (without requiring elaborate modules), drop me a
		602	note :):
		603
		604	my $daily = EV::periodic 0, 0, sub {
		605	my ($w, $now) = @_;
		606
		607	use Time::Local ();
		608	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		609	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		610	}, sub {
		611	print "it's midnight or likely shortly after, now\n";
		612	};
		613
		614	=back
		615
155	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	616	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
156		617
		618	=item $w->set ($at, $interval, $reschedule_cb)
		619
		620	Reconfigures the watcher, see the constructor above for details. Can be called at
		621	any time.
		622
		623	=item $w->again
		624
		625	Simply stops and starts the watcher again.
		626
		627	=item $time = $w->at
		628
		629	Return the time that the watcher is expected to trigger next.
		630
		631	=back
		632
		633
		634	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		635
		636	=over 4
		637
157	=item my $w = EV::signal $signum, $callback	638	=item $w = EV::signal $signal, $callback
158		639
159	=item my $w = EV::signal_ns $signum, $callback	640	=item $w = EV::signal_ns $signal, $callback
160		641
161	Call the callback when signal $signum is received.	642	Call the callback when $signal is received (the signal can be specified by
		643	number or by name, just as with C<kill> or C<%SIG>).
162		644
		645	EV will grab the signal for the process (the kernel only allows one
		646	component to receive a signal at a time) when you start a signal watcher,
		647	and removes it again when you stop it. Perl does the same when you
		648	add/remove callbacks to C<%SIG>, so watch out.
		649
		650	You can have as many signal watchers per signal as you want.
		651
163	The C<signal_ns> variant doesn't add/start the newly created watcher.	652	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
164		653
165	=back	654	=item $w->set ($signal)
166		655
167	=head1 THE EV::Event CLASS	656	Reconfigures the watcher, see the constructor above for details. Can be
		657	called at any time.
168		658
169	All EV functions creating an event watcher (designated by C<my $w =>	659	=item $current_signum = $w->signal
170	above) support the following methods on the returned watcher object:
171		660
172	=over 4	661	=item $old_signum = $w->signal ($new_signal)
173		662
174	=item $w->add ($timeout)	663	Returns the previously set signal (always as a number not name) and
		664	optionally set a new one.
175		665
176	Stops and (re-)starts the event watcher, setting the optional timeout to	666	=back
177	the given value, or clearing the timeout if none is given.
178		667
		668
		669	=head3 CHILD WATCHERS - watch out for process status changes
		670
		671	=over 4
		672
		673	=item $w = EV::child $pid, $trace, $callback
		674
		675	=item $w = EV::child_ns $pid, $trace, $callback
		676
		677	=item $w = $loop->child ($pid, $trace, $callback)
		678
		679	=item $w = $loop->child_ns ($pid, $trace, $callback)
		680
		681	Call the callback when a status change for pid C<$pid> (or any pid
		682	if C<$pid> is 0) has been received (a status change happens when the
		683	process terminates or is killed, or, when trace is true, additionally when
		684	it is stopped or continued). More precisely: when the process receives
		685	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		686	changed/zombie children and call the callback.
		687
		688	It is valid (and fully supported) to install a child watcher after a child
		689	has exited but before the event loop has started its next iteration (for
		690	example, first you C<fork>, then the new child process might exit, and
		691	only then do you install a child watcher in the parent for the new pid).
		692
		693	You can access both exit (or tracing) status and pid by using the
		694	C<rstatus> and C<rpid> methods on the watcher object.
		695
		696	You can have as many pid watchers per pid as you want, they will all be
		697	called.
		698
		699	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		700
		701	=item $w->set ($pid, $trace)
		702
		703	Reconfigures the watcher, see the constructor above for details. Can be called at
		704	any time.
		705
		706	=item $current_pid = $w->pid
		707
		708	Returns the previously set process id and optionally set a new one.
		709
		710	=item $exit_status = $w->rstatus
		711
		712	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		713	in perlfunc).
		714
		715	=item $pid = $w->rpid
		716
		717	Return the pid of the awaited child (useful when you have installed a
		718	watcher for all pids).
		719
		720	=back
		721
		722
		723	=head3 STAT WATCHERS - did the file attributes just change?
		724
		725	=over 4
		726
		727	=item $w = EV::stat $path, $interval, $callback
		728
		729	=item $w = EV::stat_ns $path, $interval, $callback
		730
		731	=item $w = $loop->stat ($path, $interval, $callback)
		732
		733	=item $w = $loop->stat_ns ($path, $interval, $callback)
		734
		735	Call the callback when a file status change has been detected on
		736	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		737	to "path does not exist" is a status change like any other.
		738
		739	The C<$interval> is a recommended polling interval for systems where
		740	OS-supported change notifications don't exist or are not supported. If
		741	you use C<0> then an unspecified default is used (which is highly
		742	recommended!), which is to be expected to be around five seconds usually.
		743
		744	This watcher type is not meant for massive numbers of stat watchers,
		745	as even with OS-supported change notifications, this can be
		746	resource-intensive.
		747
		748	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		749
179	=item $w->start	750	=item ... = $w->stat
180		751
181	Stops and (re-)starts the event watcher without touching the timeout.	752	This call is very similar to the perl C<stat> built-in: It stats (using
		753	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		754	well as EV's idea of the current stat values) to the values found.
182		755
183	=item $w->del	756	In scalar context, a boolean is return indicating success or failure of
		757	the stat. In list context, the same 13-value list as with stat is returned
		758	(except that the blksize and blocks fields are not reliable).
184		759
185	=item $w->stop	760	In the case of an error, errno is set to C<ENOENT> (regardless of the
		761	actual error value) and the C<nlink> value is forced to zero (if the stat
		762	was successful then nlink is guaranteed to be non-zero).
186		763
187	Stop the event watcher if it was started.	764	See also the next two entries for more info.
188		765
189	=item $current_callback = $w->cb	766	=item ... = $w->attr
190		767
191	=item $old_callback = $w->cb ($new_callback)	768	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		769	the values most recently detected by EV. See the next entry for more info.
192		770
		771	=item ... = $w->prev
		772
		773	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		774	the previous set of values, before the change.
		775
		776	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		777	to the values found I<before> a change was detected, while C<< $w->attr >>
		778	returns the values found leading to the change detection. The difference (if any)
		779	between C<prev> and C<attr> is what triggered the callback.
		780
		781	If you did something to the filesystem object and do not want to trigger
		782	yet another change, you can call C<stat> to update EV's idea of what the
		783	current attributes are.
		784
		785	=item $w->set ($path, $interval)
		786
		787	Reconfigures the watcher, see the constructor above for details. Can be
		788	called at any time.
		789
		790	=item $current_path = $w->path
		791
		792	=item $old_path = $w->path ($new_path)
		793
193	Return the previously set callback and optionally set a new one.	794	Returns the previously set path and optionally set a new one.
194		795
195	=item $current_fh = $w->fh	796	=item $current_interval = $w->interval
196		797
197	=item $old_fh = $w->fh ($new_fh)	798	=item $old_interval = $w->interval ($new_interval)
198		799
199	Returns the previously set filehandle and optionally set a new one.
200
201	=item $current_eventmask = $w->events
202
203	=item $old_eventmask = $w->events ($new_eventmask)
204
205	Returns the previously set event mask and optionally set a new one.	800	Returns the previously set interval and optionally set a new one. Can be
		801	used to query the actual interval used.
206		802
207	=item $w->timeout ($after, $repeat)
208
209	Resets the timeout (see C<EV::timer> for details).
210
211	=item $w->timeout_abs ($at, $interval)
212
213	Resets the timeout (see C<EV::timer_abs> for details).
214
215	=item $w->priority_set ($priority)
216
217	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
218
219	=back	803	=back
220		804
221	=head1 BUGS
222		805
223	Lots. Libevent itself isn't well tested and rather buggy, and this module	806	=head3 IDLE WATCHERS - when you've got nothing better to do...
224	is quite new at the moment.
225		807
226	Please note that the epoll method is not, in general, reliable in programs	808	=over 4
227	that use fork (even if no libveent calls are being made in the forked
228	process). If your program behaves erratically, try setting the environment
229	variable C<EVENT_NOEPOLL> first when running the program.
230		809
231	In general, if you fork, then you can only use the EV module in one of the	810	=item $w = EV::idle $callback
232	children.	811
		812	=item $w = EV::idle_ns $callback
		813
		814	=item $w = $loop->idle ($callback)
		815
		816	=item $w = $loop->idle_ns ($callback)
		817
		818	Call the callback when there are no other pending watchers of the same or
		819	higher priority (excluding check, prepare and other idle watchers of the
		820	same or lower priority, of course). They are called idle watchers because
		821	when the watcher is the highest priority pending event in the process, the
		822	process is considered to be idle at that priority.
		823
		824	If you want a watcher that is only ever called when I<no> other events are
		825	outstanding you have to set the priority to C<EV::MINPRI>.
		826
		827	The process will not block as long as any idle watchers are active, and
		828	they will be called repeatedly until stopped.
		829
		830	For example, if you have idle watchers at priority C<0> and C<1>, and
		831	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		832	and the I/O watcher will always run when ready. Only when the idle watcher
		833	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		834	pending with the C<0>-priority idle watcher be invoked.
		835
		836	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		837
		838	=back
		839
		840
		841	=head3 PREPARE WATCHERS - customise your event loop!
		842
		843	=over 4
		844
		845	=item $w = EV::prepare $callback
		846
		847	=item $w = EV::prepare_ns $callback
		848
		849	=item $w = $loop->prepare ($callback)
		850
		851	=item $w = $loop->prepare_ns ($callback)
		852
		853	Call the callback just before the process would block. You can still
		854	create/modify any watchers at this point.
		855
		856	See the EV::check watcher, below, for explanations and an example.
		857
		858	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		859
		860	=back
		861
		862
		863	=head3 CHECK WATCHERS - customise your event loop even more!
		864
		865	=over 4
		866
		867	=item $w = EV::check $callback
		868
		869	=item $w = EV::check_ns $callback
		870
		871	=item $w = $loop->check ($callback)
		872
		873	=item $w = $loop->check_ns ($callback)
		874
		875	Call the callback just after the process wakes up again (after it has
		876	gathered events), but before any other callbacks have been invoked.
		877
		878	This is used to integrate other event-based software into the EV
		879	mainloop: You register a prepare callback and in there, you create io and
		880	timer watchers as required by the other software. Here is a real-world
		881	example of integrating Net::SNMP (with some details left out):
		882
		883	our @snmp_watcher;
		884
		885	our $snmp_prepare = EV::prepare sub {
		886	# do nothing unless active
		887	$dispatcher->{_event_queue_h}
		888	or return;
		889
		890	# make the dispatcher handle any outstanding stuff
		891	... not shown
		892
		893	# create an I/O watcher for each and every socket
		894	@snmp_watcher = (
		895	(map { EV::io $_, EV::READ, sub { } }
		896	keys %{ $dispatcher->{_descriptors} }),
		897
		898	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		899	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		900	0, sub { },
		901	);
		902	};
		903
		904	The callbacks are irrelevant (and are not even being called), the
		905	only purpose of those watchers is to wake up the process as soon as
		906	one of those events occurs (socket readable, or timer timed out). The
		907	corresponding EV::check watcher will then clean up:
		908
		909	our $snmp_check = EV::check sub {
		910	# destroy all watchers
		911	@snmp_watcher = ();
		912
		913	# make the dispatcher handle any new stuff
		914	... not shown
		915	};
		916
		917	The callbacks of the created watchers will not be called as the watchers
		918	are destroyed before this cna happen (remember EV::check gets called
		919	first).
		920
		921	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		922
		923	=back
		924
		925
		926	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		927
		928	Fork watchers are called when a C<fork ()> was detected. The invocation
		929	is done before the event loop blocks next and before C<check> watchers
		930	are being called, and only in the child after the fork.
		931
		932	=over 4
		933
		934	=item $w = EV::fork $callback
		935
		936	=item $w = EV::fork_ns $callback
		937
		938	=item $w = $loop->fork ($callback)
		939
		940	=item $w = $loop->fork_ns ($callback)
		941
		942	Call the callback before the event loop is resumed in the child process
		943	after a fork.
		944
		945	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		946
		947	=back
		948
		949
		950	=head3 EMBED WATCHERS - when one backend isn't enough...
		951
		952	This is a rather advanced watcher type that lets you embed one event loop
		953	into another (currently only IO events are supported in the embedded
		954	loop, other types of watchers might be handled in a delayed or incorrect
		955	fashion and must not be used).
		956
		957	See the libev documentation at
		958	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		959	for more details.
		960
		961	In short, this watcher is most useful on BSD systems without working
		962	kqueue to still be able to handle a large number of sockets:
		963
		964	my $socket_loop;
		965
		966	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		967	if (
		968	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		969	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		970	) {
		971	# use kqueue for sockets
		972	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		973	}
		974
		975	# use the default loop otherwise
		976	$socket_loop \|\|= EV::default_loop;
		977
		978	=over 4
		979
		980	=item $w = EV::embed $otherloop, $callback
		981
		982	=item $w = EV::embed_ns $otherloop, $callback
		983
		984	=item $w = $loop->embed ($otherloop, $callback)
		985
		986	=item $w = $loop->embed_ns ($otherloop, $callback)
		987
		988	Call the callback when the embedded event loop (C<$otherloop>) has any
		989	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		990	this version of EV, which means the embedded event loop will be managed
		991	automatically.
		992
		993	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		994
		995	=back
		996
		997	=head3 ASYNC WATCHERS - how to wake up another event loop
		998
		999	Async watchers are provided by EV, but have little use in perl directly, as perl
		1000	neither supports threads nor direct access to signal handlers or other
		1001	contexts where they could be of value.
		1002
		1003	It is, however, possible to use them from the XS level.
		1004
		1005	Please see the libev documentation for further details.
		1006
		1007	=over 4
		1008
		1009	=item $w = EV::async $callback
		1010
		1011	=item $w = EV::async_ns $callback
		1012
		1013	=item $w->send
		1014
		1015	=item $bool = $w->async_pending
		1016
		1017	=back
		1018
		1019
		1020	=head1 PERL SIGNALS
		1021
		1022	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1023	with EV is as the same as any other C library: Perl-signals will only be
		1024	handled when Perl runs, which means your signal handler might be invoked
		1025	only the next time an event callback is invoked.
		1026
		1027	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1028	ensure proper operations with regards to other event watchers.
		1029
		1030	If you cannot do this for whatever reason, you can also force a watcher
		1031	to be called on every event loop iteration by installing a C<EV::check>
		1032	watcher:
		1033
		1034	my $async_check = EV::check sub { };
		1035
		1036	This ensures that perl gets into control for a short time to handle any
		1037	pending signals, and also ensures (slightly) slower overall operation.
		1038
		1039	=head1 THREADS
		1040
		1041	Threads are not supported by this module in any way. Perl pseudo-threads
		1042	is evil stuff and must die. As soon as Perl gains real threads I will work
		1043	on thread support for it.
		1044
		1045	=head1 FORK
		1046
		1047	Most of the "improved" event delivering mechanisms of modern operating
		1048	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1049	not supported and usually destructive). Libev makes it possible to work
		1050	around this by having a function that recreates the kernel state after
		1051	fork in the child.
		1052
		1053	On non-win32 platforms, this module requires the pthread_atfork
		1054	functionality to do this automatically for you. This function is quite
		1055	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1056	negligible, because everything the function currently does is set a flag
		1057	that is checked only when the event loop gets used the next time, so when
		1058	you do fork but not use EV, the overhead is minimal.
		1059
		1060	On win32, there is no notion of fork so all this doesn't apply, of course.
233		1061
234	=cut	1062	=cut
235		1063
236	our $NPRI = 4;	1064	our $DIED = sub {
237	our $BASE = init;	1065	warn "EV: error in callback (ignoring): $@";
238	priority_init $NPRI;	1066	};
239		1067
240	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];	1068	default_loop
		1069	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
241		1070
242	1;	1071	1;
243		1072
244	=head1 SEE ALSO	1073	=head1 SEE ALSO
245		1074
246	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1075	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
247	L<EV::AnyEvent>.	1076	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1077	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1078	event-loop agnostic and portable event driven programming.
248		1079
249	=head1 AUTHOR	1080	=head1 AUTHOR
250		1081
251	Marc Lehmann <schmorp@schmorp.de>	1082	Marc Lehmann <schmorp@schmorp.de>
252	http://home.schmorp.de/	1083	http://home.schmorp.de/
253		1084
254	=cut	1085	=cut
255		1086

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Comparing EV/EV.pm (file contents): Revision 1.7 by root, Sat Oct 27 14:54:20 2007 UTC vs. Revision 1.99 by root, Tue Jul 8 09:37:37 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.7 by root, Sat Oct 27 14:54:20 2007 UTC vs.
Revision 1.99 by root, Tue Jul 8 09:37:37 2008 UTC