[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 1.93 by root, Tue May 20 19:52:12 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	}
34	};	30	};
35	$w->timeout (10);	31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
36		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 libev
		61	itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
		62	subtle details on watcher semantics or some discussion on the available
		63	backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
		64	about in any case because it has much more detailed information.
		65
		66	This module is very fast and scalable. It is actually so fast that you
		67	can use it through the L<AnyEvent> module, stay portable to other event
		68	loops (if you don't rely on any watcher types not available through it)
		69	and still be faster than with any other event loop currently supported in
		70	Perl.
47		71
48	=cut	72	=cut
49		73
50	package EV;	74	package EV;
51		75
52	use strict;	76	use strict;
53		77
54	BEGIN {	78	BEGIN {
55	our $VERSION = '0.01';	79	our $VERSION = '3.4';
56	use XSLoader;	80	use XSLoader;
57	XSLoader::load "EV", $VERSION;	81	XSLoader::load "EV", $VERSION;
58	}	82	}
59		83
60	=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";
61		97
62	=over 4	98	@EV::Loop::Default::ISA = "EV::Loop";
63		99
		100	=head1 EVENT LOOPS
		101
		102	EV supports multiple event loops: There is a single "default event loop"
		103	that can handle everything including signals and child watchers, and any
		104	number of "dynamic event loops" that can use different backends (with
		105	various limitations), but no child and signal watchers.
		106
		107	You do not have to do anything to create the default event loop: When
		108	the module is loaded a suitable backend is selected on the premise of
		109	selecting a working backend (which for example rules out kqueue on most
		110	BSDs). Modules should, unless they have "special needs" always use the
		111	default loop as this is fastest (perl-wise), best supported by other
		112	modules (e.g. AnyEvent or Coro) and most portable event loop.
		113
		114	For specific programs you can create additional event loops dynamically.
		115
		116	=over 4
		117
		118	=item $loop = new EV::loop [$flags]
		119
		120	Create a new event loop as per the specified flags. Please refer to the
		121	C<ev_loop_new ()> function description in the libev documentation
		122	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		123	for more info.
		124
		125	The loop will automatically be destroyed when it is no longer referenced
		126	by any watcher and the loop object goes out of scope.
		127
		128	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		129	is protected by this module.
		130
		131	=item $loop->loop_fork
		132
		133	Must be called after a fork in the child, before entering or continuing
		134	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		135	this fucntion automatically, at some performance loss (refer to the libev
		136	documentation).
		137
		138	=item $loop = EV::default_loop [$flags]
		139
		140	Return the default loop (which is a singleton object).
		141
		142	=back
		143
		144
		145	=head1 BASIC INTERFACE
		146
		147	=over 4
		148
64	=item $EV::NPRI	149	=item $EV::DIED
65		150
66	How many priority levels are available.	151	Must contain a reference to a function that is called when a callback
		152	throws an exception (with $@ containing the error). The default prints an
		153	informative message and continues.
		154
		155	If this callback throws an exception it will be silently ignored.
		156
		157	=item $flags = EV::supported_backends
		158
		159	=item $flags = EV::recommended_backends
		160
		161	=item $flags = EV::embeddable_backends
		162
		163	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		164	instance of EV, the set of recommended backends (supposed to be good) for
		165	this platform and the set of embeddable backends (see EMBED WATCHERS).
		166
		167	=item EV::sleep $seconds
		168
		169	Block the process for the given number of (fractional) seconds.
		170
		171	=item $time = EV::time
		172
		173	Returns the current time in (fractional) seconds since the epoch.
67		174
68	=item $time = EV::now	175	=item $time = EV::now
69		176
70	Returns the time in (fractional) seconds since the epoch.	177	=item $time = $loop->now
71		178
72	=item $version = EV::version	179	Returns the time the last event loop iteration has been started. This
		180	is the time that (relative) timers are based on, and refering to it is
		181	usually faster then calling EV::time.
73		182
74	=item $method = EV::method	183	=item $backend = EV::backend
75		184
76	Return version string and event polling method used.	185	=item $backend = $loop->backend
77		186
78	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	187	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		188	or EV::METHOD_EPOLL).
79		189
80	=item EV::loopexit $after	190	=item EV::loop [$flags]
81		191
82	Exit any active loop or dispatch after C<$after> seconds or immediately if	192	=item $loop->loop ([$flags])
83	C<$after> is missing or zero.
84		193
85	=item EV::dispatch	194	Begin checking for events and calling callbacks. It returns when a
		195	callback calls EV::unloop.
86		196
87	Same as C<EV::loop 0>.	197	The $flags argument can be one of the following:
88		198
89	=item EV::event $callback	199	0 as above
		200	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		201	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
90		202
91	Creates a new event watcher waiting for nothing, calling the given callback.	203	=item EV::unloop [$how]
92		204
		205	=item $loop->unloop ([$how])
		206
		207	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		208	innermost call to EV::loop return.
		209
		210	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		211	fast as possible.
		212
		213	=item $count = EV::loop_count
		214
		215	=item $count = $loop->loop_count
		216
		217	Return the number of times the event loop has polled for new
		218	events. Sometiems useful as a generation counter.
		219
		220	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		221
		222	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		223
		224	This function rolls together an I/O and a timer watcher for a single
		225	one-shot event without the need for managing a watcher object.
		226
		227	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		228	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		229	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		230	you do not want to wait for some I/O event, specify C<undef> for
		231	C<$fh_or_undef> and C<0> for C<$events>).
		232
		233	If timeout is C<undef> or negative, then there will be no
		234	timeout. Otherwise a EV::timer with this value will be started.
		235
		236	When an error occurs or either the timeout or I/O watcher triggers, then
		237	the callback will be called with the received event set (in general
		238	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		239	C<EV::WRITE> and C<EV::TIMEOUT>).
		240
		241	EV::once doesn't return anything: the watchers stay active till either
		242	of them triggers, then they will be stopped and freed, and the callback
		243	invoked.
		244
		245	=item EV::feed_fd_event ($fd, $revents)
		246
		247	=item $loop->feed_fd_event ($fd, $revents)
		248
		249	Feed an event on a file descriptor into EV. EV will react to this call as
		250	if the readyness notifications specified by C<$revents> (a combination of
		251	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		252
		253	=item EV::feed_signal_event ($signal)
		254
		255	Feed a signal event into EV. EV will react to this call as if the signal
		256	specified by C<$signal> had occured.
		257
		258	=item EV::set_io_collect_interval $time
		259
		260	=item $loop->set_io_collect_interval ($time)
		261
		262	=item EV::set_timeout_collect_interval $time
		263
		264	=item $loop->set_timeout_collect_interval ($time)
		265
		266	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		267	wait interval for timer events. See the libev documentation at
		268	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		269	a more detailed discussion.
		270
		271	=back
		272
		273
		274	=head1 WATCHER OBJECTS
		275
		276	A watcher is an object that gets created to record your interest in some
		277	event. For instance, if you want to wait for STDIN to become readable, you
		278	would create an EV::io watcher for that:
		279
		280	my $watcher = EV::io *STDIN, EV::READ, sub {
		281	my ($watcher, $revents) = @_;
		282	warn "yeah, STDIN should now be readable without blocking!\n"
		283	};
		284
		285	All watchers can be active (waiting for events) or inactive (paused). Only
		286	active watchers will have their callbacks invoked. All callbacks will be
		287	called with at least two arguments: the watcher and a bitmask of received
		288	events.
		289
		290	Each watcher type has its associated bit in revents, so you can use the
		291	same callback for multiple watchers. The event mask is named after the
		292	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		293	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		294	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		295	uses EV::TIMEOUT).
		296
		297	In the rare case where one wants to create a watcher but not start it at
		298	the same time, each constructor has a variant with a trailing C<_ns> in
		299	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		300
		301	Please note that a watcher will automatically be stopped when the watcher
		302	object is destroyed, so you I<need> to keep the watcher objects returned by
		303	the constructors.
		304
		305	Also, all methods changing some aspect of a watcher (->set, ->priority,
		306	->fh and so on) automatically stop and start it again if it is active,
		307	which means pending events get lost.
		308
		309	=head2 COMMON WATCHER METHODS
		310
		311	This section lists methods common to all watchers.
		312
		313	=over 4
		314
		315	=item $w->start
		316
		317	Starts a watcher if it isn't active already. Does nothing to an already
		318	active watcher. By default, all watchers start out in the active state
		319	(see the description of the C<_ns> variants if you need stopped watchers).
		320
		321	=item $w->stop
		322
		323	Stop a watcher if it is active. Also clear any pending events (events that
		324	have been received but that didn't yet result in a callback invocation),
		325	regardless of whether the watcher was active or not.
		326
		327	=item $bool = $w->is_active
		328
		329	Returns true if the watcher is active, false otherwise.
		330
		331	=item $current_data = $w->data
		332
		333	=item $old_data = $w->data ($new_data)
		334
		335	Queries a freely usable data scalar on the watcher and optionally changes
		336	it. This is a way to associate custom data with a watcher:
		337
		338	my $w = EV::timer 60, 0, sub {
		339	warn $_[0]->data;
		340	};
		341	$w->data ("print me!");
		342
		343	=item $current_cb = $w->cb
		344
		345	=item $old_cb = $w->cb ($new_cb)
		346
		347	Queries the callback on the watcher and optionally changes it. You can do
		348	this at any time without the watcher restarting.
		349
		350	=item $current_priority = $w->priority
		351
		352	=item $old_priority = $w->priority ($new_priority)
		353
		354	Queries the priority on the watcher and optionally changes it. Pending
		355	watchers with higher priority will be invoked first. The valid range of
		356	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		357	-2). If the priority is outside this range it will automatically be
		358	normalised to the nearest valid priority.
		359
		360	The default priority of any newly-created watcher is 0.
		361
		362	Note that the priority semantics have not yet been fleshed out and are
		363	subject to almost certain change.
		364
		365	=item $w->invoke ($revents)
		366
		367	Call the callback now with the given event mask.
		368
		369	=item $w->feed_event ($revents)
		370
		371	Feed some events on this watcher into EV. EV will react to this call as if
		372	the watcher had received the given C<$revents> mask.
		373
		374	=item $revents = $w->clear_pending
		375
		376	If the watcher is pending, this function clears its pending status and
		377	returns its C<$revents> bitset (as if its callback was invoked). If the
		378	watcher isn't pending it does nothing and returns C<0>.
		379
		380	=item $previous_state = $w->keepalive ($bool)
		381
		382	Normally, C<EV::loop> will return when there are no active watchers
		383	(which is a "deadlock" because no progress can be made anymore). This is
		384	convinient because it allows you to start your watchers (and your jobs),
		385	call C<EV::loop> once and when it returns you know that all your jobs are
		386	finished (or they forgot to register some watchers for their task :).
		387
		388	Sometimes, however, this gets in your way, for example when the module
		389	that calls C<EV::loop> (usually the main program) is not the same module
		390	as a long-living watcher (for example a DNS client module written by
		391	somebody else even). Then you might want any outstanding requests to be
		392	handled, but you would not want to keep C<EV::loop> from returning just
		393	because you happen to have this long-running UDP port watcher.
		394
		395	In this case you can clear the keepalive status, which means that even
		396	though your watcher is active, it won't keep C<EV::loop> from returning.
		397
		398	The initial value for keepalive is true (enabled), and you cna change it
		399	any time.
		400
		401	Example: Register an I/O watcher for some UDP socket but do not keep the
		402	event loop from running just because of that watcher.
		403
		404	my $udp_socket = ...
		405	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		406	$1000udp_watcher->keepalive (0);
		407
		408	=item $loop = $w->loop
		409
		410	Return the loop that this watcher is attached to.
		411
		412	=back
		413
		414
		415	=head1 WATCHER TYPES
		416
		417	Each of the following subsections describes a single watcher type.
		418
		419	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		420
		421	=over 4
		422
93	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	423	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
94		424
95	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	425	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		426
		427	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		428
		429	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
96		430
97	As long as the returned watcher object is alive, call the C<$callback>	431	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	432	when at least one of events specified in C<$eventmask> occurs.
99	is disabled.
100		433
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:	434	The $eventmask can be one or more of these constants ORed together:
104		435
105	EV::READ wait until read() wouldn't block anymore	436	EV::READ wait until read() wouldn't block anymore
106	EV::WRITE wait until write() wouldn't block anymore	437	EV::WRITE wait until write() wouldn't block anymore
107	EV::PERSIST stay active after an event occured
108		438
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.	439	The C<io_ns> variant doesn't start (activate) the newly created watcher.
119		440
120	=item my $w = EV::timer_abs $at, $interval, $callback	441	=item $w->set ($fileno_or_fh, $eventmask)
121		442
122	=item my $w = EV::timer_abs_ns $at, $interval, $callback	443	Reconfigures the watcher, see the constructor above for details. Can be
123		444	called at any time.
124	Similar to EV::timer, but the time is given as an absolute point in time
125	(C<$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		445
178	=item $current_fh = $w->fh	446	=item $current_fh = $w->fh
179		447
180	=item $old_fh = $w->fh ($new_fh)	448	=item $old_fh = $w->fh ($new_fh)
181		449
185		453
186	=item $old_eventmask = $w->events ($new_eventmask)	454	=item $old_eventmask = $w->events ($new_eventmask)
187		455
188	Returns the previously set event mask and optionally set a new one.	456	Returns the previously set event mask and optionally set a new one.
189		457
		458	=back
		459
		460
		461	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		462
		463	=over 4
		464
		465	=item $w = EV::timer $after, $repeat, $callback
		466
		467	=item $w = EV::timer_ns $after, $repeat, $callback
		468
		469	=item $w = $loop->timer ($after, $repeat, $callback)
		470
		471	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		472
		473	Calls the callback after C<$after> seconds (which may be fractional). If
		474	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		475	value as $after) after the callback returns.
		476
		477	This means that the callback would be called roughly after C<$after>
		478	seconds, and then every C<$repeat> seconds. The timer does his best not
		479	to drift, but it will not invoke the timer more often then once per event
		480	loop iteration, and might drift in other cases. If that isn't acceptable,
		481	look at EV::periodic, which can provide long-term stable timers.
		482
		483	The timer is based on a monotonic clock, that is, if somebody is sitting
		484	in front of the machine while the timer is running and changes the system
		485	clock, the timer will nevertheless run (roughly) the same time.
		486
		487	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		488
190	=item $w->timeout ($after, $repeat)	489	=item $w->set ($after, $repeat)
191		490
192	Resets the timeout (see C<EV::timer> for details).	491	Reconfigures the watcher, see the constructor above for details. Can be called at
		492	any time.
193		493
		494	=item $w->again
		495
		496	Similar to the C<start> method, but has special semantics for repeating timers:
		497
		498	If the timer is active and non-repeating, it will be stopped.
		499
		500	If the timer is active and repeating, reset the timeout to occur
		501	C<$repeat> seconds after now.
		502
		503	If the timer is inactive and repeating, start it using the repeat value.
		504
		505	Otherwise do nothing.
		506
		507	This behaviour is useful when you have a timeout for some IO
		508	operation. You create a timer object with the same value for C<$after> and
		509	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		510	on the timeout.
		511
		512	=back
		513
		514
		515	=head3 PERIODIC WATCHERS - to cron or not to cron?
		516
		517	=over 4
		518
		519	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		520
		521	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		522
		523	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		524
		525	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		526
		527	Similar to EV::timer, but is not based on relative timeouts but on
		528	absolute times. Apart from creating "simple" timers that trigger "at" the
		529	specified time, it can also be used for non-drifting absolute timers and
		530	more complex, cron-like, setups that are not adversely affected by time
		531	jumps (i.e. when the system clock is changed by explicit date -s or other
		532	means such as ntpd). It is also the most complex watcher type in EV.
		533
		534	It has three distinct "modes":
		535
		536	=over 4
		537
		538	=item * absolute timer ($interval = $reschedule_cb = 0)
		539
		540	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		541	will not adjust when a time jump occurs, that is, if it is to be run
		542	at January 1st 2011 then it will run when the system time reaches or
		543	surpasses this time.
		544
		545	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		546
		547	In this mode the watcher will always be scheduled to time out at the
		548	next C<$at + N * $interval> time (for some integer N) and then repeat,
		549	regardless of any time jumps.
		550
		551	This can be used to create timers that do not drift with respect to system
		552	time:
		553
		554	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		555
		556	That doesn't mean there will always be 3600 seconds in between triggers,
		557	but only that the the clalback will be called when the system time shows a
		558	full hour (UTC).
		559
		560	Another way to think about it (for the mathematically inclined) is that
		561	EV::periodic will try to run the callback in this mode at the next
		562	possible time where C<$time = $at (mod $interval)>, regardless of any time
		563	jumps.
		564
		565	=item * manual reschedule mode ($reschedule_cb = coderef)
		566
		567	In this mode $interval and $at are both being ignored. Instead, each
		568	time the periodic watcher gets scheduled, the reschedule callback
		569	($reschedule_cb) will be called with the watcher as first, and the current
		570	time as second argument.
		571
		572	I<This callback MUST NOT stop or destroy this or any other periodic
		573	watcher, ever>. If you need to stop it, return 1e30 and stop it
		574	afterwards.
		575
		576	It must return the next time to trigger, based on the passed time value
		577	(that is, the lowest time value larger than to the second argument). It
		578	will usually be called just before the callback will be triggered, but
		579	might be called at other times, too.
		580
		581	This can be used to create very complex timers, such as a timer that
		582	triggers on each midnight, local time (actually 24 hours after the last
		583	midnight, to keep the example simple. If you know a way to do it correctly
		584	in about the same space (without requiring elaborate modules), drop me a
		585	note :):
		586
		587	my $daily = EV::periodic 0, 0, sub {
		588	my ($w, $now) = @_;
		589
		590	use Time::Local ();
		591	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		592	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		593	}, sub {
		594	print "it's midnight or likely shortly after, now\n";
		595	};
		596
		597	=back
		598
		599	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		600
		601	=item $w->set ($at, $interval, $reschedule_cb)
		602
		603	Reconfigures the watcher, see the constructor above for details. Can be called at
		604	any time.
		605
		606	=item $w->again
		607
		608	Simply stops and starts the watcher again.
		609
		610	=item $time = $w->at
		611
		612	Return the time that the watcher is expected to trigger next.
		613
		614	=back
		615
		616
		617	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		618
		619	=over 4
		620
		621	=item $w = EV::signal $signal, $callback
		622
		623	=item $w = EV::signal_ns $signal, $callback
		624
		625	Call the callback when $signal is received (the signal can be specified by
		626	number or by name, just as with C<kill> or C<%SIG>).
		627
		628	EV will grab the signal for the process (the kernel only allows one
		629	component to receive a signal at a time) when you start a signal watcher,
		630	and removes it again when you stop it. Perl does the same when you
		631	add/remove callbacks to C<%SIG>, so watch out.
		632
		633	You can have as many signal watchers per signal as you want.
		634
		635	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		636
		637	=item $w->set ($signal)
		638
		639	Reconfigures the watcher, see the constructor above for details. Can be
		640	called at any time.
		641
		642	=item $current_signum = $w->signal
		643
		644	=item $old_signum = $w->signal ($new_signal)
		645
		646	Returns the previously set signal (always as a number not name) and
		647	optionally set a new one.
		648
		649	=back
		650
		651
		652	=head3 CHILD WATCHERS - watch out for process status changes
		653
		654	=over 4
		655
		656	=item $w = EV::child $pid, $trace, $callback
		657
		658	=item $w = EV::child_ns $pid, $trace, $callback
		659
		660	=item $w = $loop->child ($pid, $trace, $callback)
		661
		662	=item $w = $loop->child_ns ($pid, $trace, $callback)
		663
		664	Call the callback when a status change for pid C<$pid> (or any pid
		665	if C<$pid> is 0) has been received (a status change happens when the
		666	process terminates or is killed, or, when trace is true, additionally when
		667	it is stopped or continued). More precisely: when the process receives
		668	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		669	changed/zombie children and call the callback.
		670
		671	It is valid (and fully supported) to install a child watcher after a child
		672	has exited but before the event loop has started its next iteration (for
		673	example, first you C<fork>, then the new child process might exit, and
		674	only then do you install a child watcher in the parent for the new pid).
		675
		676	You can access both exit (or tracing) status and pid by using the
		677	C<rstatus> and C<rpid> methods on the watcher object.
		678
		679	You can have as many pid watchers per pid as you want, they will all be
		680	called.
		681
		682	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		683
		684	=item $w->set ($pid, $trace)
		685
		686	Reconfigures the watcher, see the constructor above for details. Can be called at
		687	any time.
		688
		689	=item $current_pid = $w->pid
		690
		691	Returns the previously set process id and optionally set a new one.
		692
		693	=item $exit_status = $w->rstatus
		694
		695	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		696	in perlfunc).
		697
		698	=item $pid = $w->rpid
		699
		700	Return the pid of the awaited child (useful when you have installed a
		701	watcher for all pids).
		702
		703	=back
		704
		705
		706	=head3 STAT WATCHERS - did the file attributes just change?
		707
		708	=over 4
		709
		710	=item $w = EV::stat $path, $interval, $callback
		711
		712	=item $w = EV::stat_ns $path, $interval, $callback
		713
		714	=item $w = $loop->stat ($path, $interval, $callback)
		715
		716	=item $w = $loop->stat_ns ($path, $interval, $callback)
		717
		718	Call the callback when a file status change has been detected on
		719	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		720	to "path does not exist" is a status change like any other.
		721
		722	The C<$interval> is a recommended polling interval for systems where
		723	OS-supported change notifications don't exist or are not supported. If
		724	you use C<0> then an unspecified default is used (which is highly
		725	recommended!), which is to be expected to be around five seconds usually.
		726
		727	This watcher type is not meant for massive numbers of stat watchers,
		728	as even with OS-supported change notifications, this can be
		729	resource-intensive.
		730
		731	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		732
		733	=item ... = $w->stat
		734
		735	This call is very similar to the perl C<stat> built-in: It stats (using
		736	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		737	well as EV's idea of the current stat values) to the values found.
		738
		739	In scalar context, a boolean is return indicating success or failure of
		740	the stat. In list context, the same 13-value list as with stat is returned
		741	(except that the blksize and blocks fields are not reliable).
		742
		743	In the case of an error, errno is set to C<ENOENT> (regardless of the
		744	actual error value) and the C<nlink> value is forced to zero (if the stat
		745	was successful then nlink is guaranteed to be non-zero).
		746
		747	See also the next two entries for more info.
		748
		749	=item ... = $w->attr
		750
		751	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		752	the values most recently detected by EV. See the next entry for more info.
		753
		754	=item ... = $w->prev
		755
		756	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		757	the previous set of values, before the change.
		758
		759	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		760	to the values found I<before> a change was detected, while C<< $w->attr >>
		761	returns the values found leading to the change detection. The difference (if any)
		762	between C<prev> and C<attr> is what triggered the callback.
		763
		764	If you did something to the filesystem object and do not want to trigger
		765	yet another change, you can call C<stat> to update EV's idea of what the
		766	current attributes are.
		767
194	=item $w->timeout_abs ($at, $interval)	768	=item $w->set ($path, $interval)
195		769
196	Resets the timeout (see C<EV::timer_abs> for details).	770	Reconfigures the watcher, see the constructor above for details. Can be
		771	called at any time.
197		772
198	=item $w->priority_set ($priority)	773	=item $current_path = $w->path
199		774
200	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	775	=item $old_path = $w->path ($new_path)
201		776
202	=back	777	Returns the previously set path and optionally set a new one.
203		778
204	=head1 BUGS	779	=item $current_interval = $w->interval
205		780
206	Lots. Libevent itself isn't well tested and rather buggy, and this module	781	=item $old_interval = $w->interval ($new_interval)
207	is quite new at the moment.	782
		783	Returns the previously set interval and optionally set a new one. Can be
		784	used to query the actual interval used.
		785
		786	=back
		787
		788
		789	=head3 IDLE WATCHERS - when you've got nothing better to do...
		790
		791	=over 4
		792
		793	=item $w = EV::idle $callback
		794
		795	=item $w = EV::idle_ns $callback
		796
		797	=item $w = $loop->idle ($callback)
		798
		799	=item $w = $loop->idle_ns ($callback)
		800
		801	Call the callback when there are no other pending watchers of the same or
		802	higher priority (excluding check, prepare and other idle watchers of the
		803	same or lower priority, of course). They are called idle watchers because
		804	when the watcher is the highest priority pending event in the process, the
		805	process is considered to be idle at that priority.
		806
		807	If you want a watcher that is only ever called when I<no> other events are
		808	outstanding you have to set the priority to C<EV::MINPRI>.
		809
		810	The process will not block as long as any idle watchers are active, and
		811	they will be called repeatedly until stopped.
		812
		813	For example, if you have idle watchers at priority C<0> and C<1>, and
		814	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		815	and the I/O watcher will always run when ready. Only when the idle watcher
		816	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		817	pending with the C<0>-priority idle watcher be invoked.
		818
		819	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		820
		821	=back
		822
		823
		824	=head3 PREPARE WATCHERS - customise your event loop!
		825
		826	=over 4
		827
		828	=item $w = EV::prepare $callback
		829
		830	=item $w = EV::prepare_ns $callback
		831
		832	=item $w = $loop->prepare ($callback)
		833
		834	=item $w = $loop->prepare_ns ($callback)
		835
		836	Call the callback just before the process would block. You can still
		837	create/modify any watchers at this point.
		838
		839	See the EV::check watcher, below, for explanations and an example.
		840
		841	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		842
		843	=back
		844
		845
		846	=head3 CHECK WATCHERS - customise your event loop even more!
		847
		848	=over 4
		849
		850	=item $w = EV::check $callback
		851
		852	=item $w = EV::check_ns $callback
		853
		854	=item $w = $loop->check ($callback)
		855
		856	=item $w = $loop->check_ns ($callback)
		857
		858	Call the callback just after the process wakes up again (after it has
		859	gathered events), but before any other callbacks have been invoked.
		860
		861	This is used to integrate other event-based software into the EV
		862	mainloop: You register a prepare callback and in there, you create io and
		863	timer watchers as required by the other software. Here is a real-world
		864	example of integrating Net::SNMP (with some details left out):
		865
		866	our @snmp_watcher;
		867
		868	our $snmp_prepare = EV::prepare sub {
		869	# do nothing unless active
		870	$dispatcher->{_event_queue_h}
		871	or return;
		872
		873	# make the dispatcher handle any outstanding stuff
		874	... not shown
		875
		876	# create an I/O watcher for each and every socket
		877	@snmp_watcher = (
		878	(map { EV::io $_, EV::READ, sub { } }
		879	keys %{ $dispatcher->{_descriptors} }),
		880
		881	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		882	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		883	0, sub { },
		884	);
		885	};
		886
		887	The callbacks are irrelevant (and are not even being called), the
		888	only purpose of those watchers is to wake up the process as soon as
		889	one of those events occurs (socket readable, or timer timed out). The
		890	corresponding EV::check watcher will then clean up:
		891
		892	our $snmp_check = EV::check sub {
		893	# destroy all watchers
		894	@snmp_watcher = ();
		895
		896	# make the dispatcher handle any new stuff
		897	... not shown
		898	};
		899
		900	The callbacks of the created watchers will not be called as the watchers
		901	are destroyed before this cna happen (remember EV::check gets called
		902	first).
		903
		904	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		905
		906	=back
		907
		908
		909	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		910
		911	Fork watchers are called when a C<fork ()> was detected. The invocation
		912	is done before the event loop blocks next and before C<check> watchers
		913	are being called, and only in the child after the fork.
		914
		915	=over 4
		916
		917	=item $w = EV::fork $callback
		918
		919	=item $w = EV::fork_ns $callback
		920
		921	=item $w = $loop->fork ($callback)
		922
		923	=item $w = $loop->fork_ns ($callback)
		924
		925	Call the callback before the event loop is resumed in the child process
		926	after a fork.
		927
		928	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		929
		930	=back
		931
		932
		933	=head3 EMBED WATCHERS - when one backend isn't enough...
		934
		935	This is a rather advanced watcher type that lets you embed one event loop
		936	into another (currently only IO events are supported in the embedded
		937	loop, other types of watchers might be handled in a delayed or incorrect
		938	fashion and must not be used).
		939
		940	See the libev documentation at
		941	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		942	for more details.
		943
		944	In short, this watcher is most useful on BSD systems without working
		945	kqueue to still be able to handle a large number of sockets:
		946
		947	my $socket_loop;
		948
		949	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		950	if (
		951	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		952	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		953	) {
		954	# use kqueue for sockets
		955	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		956	}
		957
		958	# use the default loop otherwise
		959	$socket_loop \|\|= EV::default_loop;
		960
		961	=over 4
		962
		963	=item $w = EV::embed $otherloop, $callback
		964
		965	=item $w = EV::embed_ns $otherloop, $callback
		966
		967	=item $w = $loop->embed ($otherloop, $callback)
		968
		969	=item $w = $loop->embed_ns ($otherloop, $callback)
		970
		971	Call the callback when the embedded event loop (C<$otherloop>) has any
		972	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		973	this version of EV, which means the embedded event loop will be managed
		974	automatically.
		975
		976	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		977
		978	=back
		979
		980	=head3 ASYNC WATCHERS - how to wake up another event loop
		981
		982	Async watchers are provided by EV, but have little use in perl directly, as perl
		983	neither supports threads nor direct access to signal handlers or other
		984	contexts where they could be of value.
		985
		986	It is, however, possible to use them from the XS level.
		987
		988	Please see the libev documentation for further details.
		989
		990	=over 4
		991
		992	=item $w = EV::async $callback
		993
		994	=item $w = EV::async_ns $callback
		995
		996	=item $w->send
		997
		998	=item $bool = $w->async_pending
		999
		1000	=back
		1001
		1002
		1003	=head1 PERL SIGNALS
		1004
		1005	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1006	with EV is as the same as any other C library: Perl-signals will only be
		1007	handled when Perl runs, which means your signal handler might be invoked
		1008	only the next time an event callback is invoked.
		1009
		1010	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1011	ensure proper operations with regards to other event watchers.
		1012
		1013	If you cannot do this for whatever reason, you can also force a watcher
		1014	to be called on every event loop iteration by installing a C<EV::check>
		1015	watcher:
		1016
		1017	my $async_check = EV::check sub { };
		1018
		1019	This ensures that perl gets into control for a short time to handle any
		1020	pending signals, and also ensures (slightly) slower overall operation.
		1021
		1022	=head1 THREADS
		1023
		1024	Threads are not supported by this module in any way. Perl pseudo-threads
		1025	is evil stuff and must die. As soon as Perl gains real threads I will work
		1026	on thread support for it.
		1027
		1028	=head1 FORK
		1029
		1030	Most of the "improved" event delivering mechanisms of modern operating
		1031	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1032	not supported and usually destructive). Libev makes it possible to work
		1033	around this by having a function that recreates the kernel state after
		1034	fork in the child.
		1035
		1036	On non-win32 platforms, this module requires the pthread_atfork
		1037	functionality to do this automatically for you. This function is quite
		1038	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1039	negligible, because everything the function currently does is set a flag
		1040	that is checked only when the event loop gets used the next time, so when
		1041	you do fork but not use EV, the overhead is minimal.
		1042
		1043	On win32, there is no notion of fork so all this doesn't apply, of course.
208		1044
209	=cut	1045	=cut
210		1046
211	our $NPRI = 4;	1047	our $DIED = sub {
212	our $BASE = init;	1048	warn "EV: error in callback (ignoring): $@";
213	priority_init $NPRI;	1049	};
		1050
		1051	default_loop
		1052	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
214		1053
215	1;	1054	1;
216		1055
217	=head1 SEE ALSO	1056	=head1 SEE ALSO
218		1057
219	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1058	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
		1059	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1060	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1061	event-loop agnostic and portable event driven programming.
220		1062
221	=head1 AUTHOR	1063	=head1 AUTHOR
222		1064
223	Marc Lehmann <schmorp@schmorp.de>	1065	Marc Lehmann <schmorp@schmorp.de>
224	http://home.schmorp.de/	1066	http://home.schmorp.de/

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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 1.93 by root, Tue May 20 19:52:12 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 1.93 by root, Tue May 20 19:52:12 2008 UTC