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

Comparing EV/EV.pm (file contents):
Revision 1.9 by root, Sun Oct 28 06:40:46 2007 UTC vs.
Revision 1.83 by root, Mon Jan 28 12:24:05 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/>). 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://cvs.schmorp.de/libev/ev.html>) for more subtle details on
49		62	watcher semantics or some discussion on the available backends, or how to
50	Please note thta this module disables the libevent EPOLL method by	63	force a specific backend with C<LIBEV_FLAGS>, or just about in any case
51	default, see BUGS, below, if you need to enable it.	64	because it has much more detailed information.
52		65
53	=cut	66	=cut
54		67
55	package EV;	68	package EV;
56		69
57	use strict;	70	use strict;
58		71
59	BEGIN {	72	BEGIN {
60	our $VERSION = '0.02';	73	our $VERSION = '3.0';
61	use XSLoader;	74	use XSLoader;
62	XSLoader::load "EV", $VERSION;	75	XSLoader::load "EV", $VERSION;
63	}	76	}
64		77
		78	@EV::IO::ISA =
		79	@EV::Timer::ISA =
		80	@EV::Periodic::ISA =
		81	@EV::Signal::ISA =
		82	@EV::Child::ISA =
		83	@EV::Stat::ISA =
		84	@EV::Idle::ISA =
		85	@EV::Prepare::ISA =
		86	@EV::Check::ISA =
		87	@EV::Embed::ISA =
		88	@EV::Fork::ISA =
		89	"EV::Watcher";
		90
		91	@EV::Loop::Default::ISA = "EV::Loop";
		92
		93	=head1 EVENT LOOPS
		94
		95	EV supports multiple event loops: There is a single "default event loop"
		96	that can handle everything including signals and child watchers, and any
		97	number of "dynamic event loops" that can use different backends (with
		98	various limitations), but no child and signal watchers.
		99
		100	You do not have to do anything to create the default event loop: When
		101	the module is loaded a suitable backend is selected on the premise of
		102	selecting a working backend (which for example rules out kqueue on most
		103	BSDs). Modules should, unless they have "special needs" always use the
		104	default loop as this is fastest (perl-wise), best supported by other
		105	modules (e.g. AnyEvent or Coro) and most portable event loop.
		106
		107	For specific programs you can create additional event loops dynamically.
		108
		109	=over 4
		110
		111	=item $loop = new EV::loop [$flags]
		112
		113	Create a new event loop as per the specified flags. Please refer to the
		114	C<ev_loop_new ()> function description in the libev documentation
		115	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		116	for more info.
		117
		118	The loop will automatically be destroyed when it is no longer referenced
		119	by any watcher and the loop object goes out of scope.
		120
		121	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		122	is protected by this module.
		123
		124	=item $loop->loop_fork
		125
		126	Must be called after a fork in the child, before entering or continuing
		127	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		128	this fucntion automatically, at some performance loss (refer to the libev
		129	documentation).
		130
		131	=item $loop = EV::default_loop [$flags]
		132
		133	Return the default loop (which is a singleton object).
		134
		135	=back
		136
		137
65	=head1 BASIC INTERFACE	138	=head1 BASIC INTERFACE
66		139
67	=over 4	140	=over 4
68		141
69	=item $EV::NPRI
70
71	How many priority levels are available.
72
73	=item $EV::DIED	142	=item $EV::DIED
74		143
75	Must contain a reference to a function that is called when a callback	144	Must contain a reference to a function that is called when a callback
76	throws an exception (with $@ containing thr error). The default prints an	145	throws an exception (with $@ containing the error). The default prints an
77	informative message and continues.	146	informative message and continues.
78		147
79	If this callback throws an exception it will be silently ignored.	148	If this callback throws an exception it will be silently ignored.
80		149
		150	=item $flags = EV::supported_backends
		151
		152	=item $flags = EV::recommended_backends
		153
		154	=item $flags = EV::embeddable_backends
		155
		156	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		157	instance of EV, the set of recommended backends (supposed to be good) for
		158	this platform and the set of embeddable backends (see EMBED WATCHERS).
		159
		160	=item EV::sleep $seconds
		161
		162	Block the process for the given number of (fractional) seconds.
		163
		164	=item $time = EV::time
		165
		166	Returns the current time in (fractional) seconds since the epoch.
		167
81	=item $time = EV::now	168	=item $time = EV::now
82		169
83	Returns the time in (fractional) seconds since the epoch.	170	=item $time = $loop->now
84		171
85	=item $version = EV::version	172	Returns the time the last event loop iteration has been started. This
		173	is the time that (relative) timers are based on, and refering to it is
		174	usually faster then calling EV::time.
86		175
87	=item $method = EV::method	176	=item $backend = EV::backend
88		177
89	Return version string and event polling method used.	178	=item $backend = $loop->backend
90		179
91	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	180	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		181	or EV::METHOD_EPOLL).
92		182
93	=item EV::loopexit $after	183	=item EV::loop [$flags]
94		184
95	Exit any active loop or dispatch after C<$after> seconds or immediately if	185	=item $loop->loop ([$flags])
96	C<$after> is missing or zero.
97		186
98	=item EV::dispatch	187	Begin checking for events and calling callbacks. It returns when a
		188	callback calls EV::unloop.
99		189
100	Same as C<EV::loop 0>.	190	The $flags argument can be one of the following:
101		191
102	=item EV::event $callback	192	0 as above
		193	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		194	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
103		195
104	Creates a new event watcher waiting for nothing, calling the given callback.	196	=item EV::unloop [$how]
105		197
		198	=item $loop->unloop ([$how])
		199
		200	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		201	innermost call to EV::loop return.
		202
		203	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		204	fast as possible.
		205
		206	=item $count = EV::loop_count
		207
		208	=item $count = $loop->loop_count
		209
		210	Return the number of times the event loop has polled for new
		211	events. Sometiems useful as a generation counter.
		212
		213	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		214
		215	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		216
		217	This function rolls together an I/O and a timer watcher for a single
		218	one-shot event without the need for managing a watcher object.
		219
		220	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		221	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		222	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		223	you do not want to wait for some I/O event, specify C<undef> for
		224	C<$fh_or_undef> and C<0> for C<$events>).
		225
		226	If timeout is C<undef> or negative, then there will be no
		227	timeout. Otherwise a EV::timer with this value will be started.
		228
		229	When an error occurs or either the timeout or I/O watcher triggers, then
		230	the callback will be called with the received event set (in general
		231	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		232	C<EV::WRITE> and C<EV::TIMEOUT>).
		233
		234	EV::once doesn't return anything: the watchers stay active till either
		235	of them triggers, then they will be stopped and freed, and the callback
		236	invoked.
		237
		238	=item EV::feed_fd_event ($fd, $revents)
		239
		240	=item $loop->feed_fd_event ($fd, $revents)
		241
		242	Feed an event on a file descriptor into EV. EV will react to this call as
		243	if the readyness notifications specified by C<$revents> (a combination of
		244	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		245
		246	=item EV::feed_signal_event ($signal)
		247
		248	Feed a signal event into EV. EV will react to this call as if the signal
		249	specified by C<$signal> had occured.
		250
		251	=item EV::set_io_collect_interval $time
		252
		253	=item $loop->set_io_collect_interval ($time)
		254
		255	=item EV::set_timeout_collect_interval $time
		256
		257	=item $loop->set_timeout_collect_interval ($time)
		258
		259	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		260	wait interval for timer events. See the libev documentation at
		261	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		262	a more detailed discussion.
		263
		264	=back
		265
		266
		267	=head1 WATCHER OBJECTS
		268
		269	A watcher is an object that gets created to record your interest in some
		270	event. For instance, if you want to wait for STDIN to become readable, you
		271	would create an EV::io watcher for that:
		272
		273	my $watcher = EV::io *STDIN, EV::READ, sub {
		274	my ($watcher, $revents) = @_;
		275	warn "yeah, STDIN should now be readable without blocking!\n"
		276	};
		277
		278	All watchers can be active (waiting for events) or inactive (paused). Only
		279	active watchers will have their callbacks invoked. All callbacks will be
		280	called with at least two arguments: the watcher and a bitmask of received
		281	events.
		282
		283	Each watcher type has its associated bit in revents, so you can use the
		284	same callback for multiple watchers. The event mask is named after the
		285	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		286	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		287	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		288	uses EV::TIMEOUT).
		289
		290	In the rare case where one wants to create a watcher but not start it at
		291	the same time, each constructor has a variant with a trailing C<_ns> in
		292	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		293
		294	Please note that a watcher will automatically be stopped when the watcher
		295	object is destroyed, so you I<need> to keep the watcher objects returned by
		296	the constructors.
		297
		298	Also, all methods changing some aspect of a watcher (->set, ->priority,
		299	->fh and so on) automatically stop and start it again if it is active,
		300	which means pending events get lost.
		301
		302	=head2 COMMON WATCHER METHODS
		303
		304	This section lists methods common to all watchers.
		305
		306	=over 4
		307
		308	=item $w->start
		309
		310	Starts a watcher if it isn't active already. Does nothing to an already
		311	active watcher. By default, all watchers start out in the active state
		312	(see the description of the C<_ns> variants if you need stopped watchers).
		313
		314	=item $w->stop
		315
		316	Stop a watcher if it is active. Also clear any pending events (events that
		317	have been received but that didn't yet result in a callback invocation),
		318	regardless of whether the watcher was active or not.
		319
		320	=item $bool = $w->is_active
		321
		322	Returns true if the watcher is active, false otherwise.
		323
		324	=item $current_data = $w->data
		325
		326	=item $old_data = $w->data ($new_data)
		327
		328	Queries a freely usable data scalar on the watcher and optionally changes
		329	it. This is a way to associate custom data with a watcher:
		330
		331	my $w = EV::timer 60, 0, sub {
		332	warn $_[0]->data;
		333	};
		334	$w->data ("print me!");
		335
		336	=item $current_cb = $w->cb
		337
		338	=item $old_cb = $w->cb ($new_cb)
		339
		340	Queries the callback on the watcher and optionally changes it. You can do
		341	this at any time without the watcher restarting.
		342
		343	=item $current_priority = $w->priority
		344
		345	=item $old_priority = $w->priority ($new_priority)
		346
		347	Queries the priority on the watcher and optionally changes it. Pending
		348	watchers with higher priority will be invoked first. The valid range of
		349	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		350	-2). If the priority is outside this range it will automatically be
		351	normalised to the nearest valid priority.
		352
		353	The default priority of any newly-created watcher is 0.
		354
		355	Note that the priority semantics have not yet been fleshed out and are
		356	subject to almost certain change.
		357
		358	=item $w->invoke ($revents)
		359
		360	Call the callback now with the given event mask.
		361
		362	=item $w->feed_event ($revents)
		363
		364	Feed some events on this watcher into EV. EV will react to this call as if
		365	the watcher had received the given C<$revents> mask.
		366
		367	=item $revents = $w->clear_pending
		368
		369	If the watcher is pending, this function clears its pending status and
		370	returns its C<$revents> bitset (as if its callback was invoked). If the
		371	watcher isn't pending it does nothing and returns C<0>.
		372
		373	=item $previous_state = $w->keepalive ($bool)
		374
		375	Normally, C<EV::loop> will return when there are no active watchers
		376	(which is a "deadlock" because no progress can be made anymore). This is
		377	convinient because it allows you to start your watchers (and your jobs),
		378	call C<EV::loop> once and when it returns you know that all your jobs are
		379	finished (or they forgot to register some watchers for their task :).
		380
		381	Sometimes, however, this gets in your way, for example when the module
		382	that calls C<EV::loop> (usually the main program) is not the same module
		383	as a long-living watcher (for example a DNS client module written by
		384	somebody else even). Then you might want any outstanding requests to be
		385	handled, but you would not want to keep C<EV::loop> from returning just
		386	because you happen to have this long-running UDP port watcher.
		387
		388	In this case you can clear the keepalive status, which means that even
		389	though your watcher is active, it won't keep C<EV::loop> from returning.
		390
		391	The initial value for keepalive is true (enabled), and you cna change it
		392	any time.
		393
		394	Example: Register an I/O watcher for some UDP socket but do not keep the
		395	event loop from running just because of that watcher.
		396
		397	my $udp_socket = ...
		398	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		399	$1000udp_watcher->keepalive (0);
		400
		401	=item $loop = $w->loop
		402
		403	Return the loop that this watcher is attached to.
		404
		405	=back
		406
		407
		408	=head1 WATCHER TYPES
		409
		410	Each of the following subsections describes a single watcher type.
		411
		412	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		413
		414	=over 4
		415
106	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	416	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
107		417
108	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	418	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		419
		420	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		421
		422	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
109		423
110	As long as the returned watcher object is alive, call the C<$callback>	424	As long as the returned watcher object is alive, call the C<$callback>
111	when the events specified in C<$eventmask> happen. Initially, the timeout	425	when at least one of events specified in C<$eventmask> occurs.
112	is disabled.
113		426
114	Youc an additionall set a timeout to occur on the watcher, but note that
115	this timeout will not be reset when you get an I/O event in the EV::PERSIST
116	case, and reaching a timeout will always stop the watcher even in the
117	EV::PERSIST case.
118
119	If you want a timeout to occur only after a specific time of inactivity, set
120	a repeating timeout and do NOT use EV::PERSIST.
121
122	Eventmask can be one or more of these constants ORed together:	427	The $eventmask can be one or more of these constants ORed together:
123		428
124	EV::READ wait until read() wouldn't block anymore	429	EV::READ wait until read() wouldn't block anymore
125	EV::WRITE wait until write() wouldn't block anymore	430	EV::WRITE wait until write() wouldn't block anymore
126	EV::PERSIST stay active after a (non-timeout) event occured
127		431
128	The C<io_ns> variant doesn't add/start the newly created watcher.	432	The C<io_ns> variant doesn't start (activate) the newly created watcher.
129		433
		434	=item $w->set ($fileno_or_fh, $eventmask)
		435
		436	Reconfigures the watcher, see the constructor above for details. Can be
		437	called at any time.
		438
		439	=item $current_fh = $w->fh
		440
		441	=item $old_fh = $w->fh ($new_fh)
		442
		443	Returns the previously set filehandle and optionally set a new one.
		444
		445	=item $current_eventmask = $w->events
		446
		447	=item $old_eventmask = $w->events ($new_eventmask)
		448
		449	Returns the previously set event mask and optionally set a new one.
		450
		451	=back
		452
		453
		454	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		455
		456	=over 4
		457
130	=item my $w = EV::timer $after, $repeat, $callback	458	=item $w = EV::timer $after, $repeat, $callback
131		459
132	=item my $w = EV::timer_ns $after, $repeat, $callback	460	=item $w = EV::timer_ns $after, $repeat, $callback
133		461
134	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	462	=item $w = $loop->timer ($after, $repeat, $callback)
135	timer will be restarted after the callback returns. This means that the
136	callback would be called roughly every C<$after> seconds, prolonged by the
137	time the callback takes.
138		463
		464	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		465
		466	Calls the callback after C<$after> seconds (which may be fractional). If
		467	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		468	value as $after) after the callback returns.
		469
		470	This means that the callback would be called roughly after C<$after>
		471	seconds, and then every C<$repeat> seconds. The timer does his best not
		472	to drift, but it will not invoke the timer more often then once per event
		473	loop iteration, and might drift in other cases. If that isn't acceptable,
		474	look at EV::periodic, which can provide long-term stable timers.
		475
		476	The timer is based on a monotonic clock, that is, if somebody is sitting
		477	in front of the machine while the timer is running and changes the system
		478	clock, the timer will nevertheless run (roughly) the same time.
		479
139	The C<timer_ns> variant doesn't add/start the newly created watcher.	480	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
140		481
141	=item my $w = EV::timer_abs $at, $interval, $callback	482	=item $w->set ($after, $repeat)
142		483
143	=item my $w = EV::timer_abs_ns $at, $interval, $callback	484	Reconfigures the watcher, see the constructor above for details. Can be called at
		485	any time.
144		486
145	Similar to EV::timer, but the time is given as an absolute point in time	487	=item $w->again
146	(C<$at>), plus an optional C<$interval>.
147		488
148	If the C<$interval> is zero, then the callback will be called at the time	489	Similar to the C<start> method, but has special semantics for repeating timers:
149	C<$at> if that is in the future, or as soon as possible if its in the
150	past. It will not automatically repeat.
151		490
152	If the C<$interval> is nonzero, then the watcher will always be scheduled	491	If the timer is active and non-repeating, it will be stopped.
153	to time out at the next C<$at + integer * $interval> time.
154		492
155	This can be used to schedule a callback to run at very regular intervals,	493	If the timer is active and repeating, reset the timeout to occur
156	as long as the processing time is less then the interval (otherwise	494	C<$repeat> seconds after now.
157	obviously events will be skipped).	495
		496	If the timer is inactive and repeating, start it using the repeat value.
		497
		498	Otherwise do nothing.
		499
		500	This behaviour is useful when you have a timeout for some IO
		501	operation. You create a timer object with the same value for C<$after> and
		502	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		503	on the timeout.
		504
		505	=back
		506
		507
		508	=head3 PERIODIC WATCHERS - to cron or not to cron?
		509
		510	=over 4
		511
		512	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		513
		514	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		515
		516	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		517
		518	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		519
		520	Similar to EV::timer, but is not based on relative timeouts but on
		521	absolute times. Apart from creating "simple" timers that trigger "at" the
		522	specified time, it can also be used for non-drifting absolute timers and
		523	more complex, cron-like, setups that are not adversely affected by time
		524	jumps (i.e. when the system clock is changed by explicit date -s or other
		525	means such as ntpd). It is also the most complex watcher type in EV.
		526
		527	It has three distinct "modes":
		528
		529	=over 4
		530
		531	=item * absolute timer ($interval = $reschedule_cb = 0)
		532
		533	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		534	will not adjust when a time jump occurs, that is, if it is to be run
		535	at January 1st 2011 then it will run when the system time reaches or
		536	surpasses this time.
		537
		538	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		539
		540	In this mode the watcher will always be scheduled to time out at the
		541	next C<$at + N * $interval> time (for some integer N) and then repeat,
		542	regardless of any time jumps.
		543
		544	This can be used to create timers that do not drift with respect to system
		545	time:
		546
		547	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		548
		549	That doesn't mean there will always be 3600 seconds in between triggers,
		550	but only that the the clalback will be called when the system time shows a
		551	full hour (UTC).
158		552
159	Another way to think about it (for the mathematically inclined) is that	553	Another way to think about it (for the mathematically inclined) is that
160	C<timer_abs> will try to tun the callback at the next possible time where	554	EV::periodic will try to run the callback in this mode at the next
161	C<$time = $at (mod $interval)>, regardless of any time jumps.	555	possible time where C<$time = $at (mod $interval)>, regardless of any time
		556	jumps.
162		557
		558	=item * manual reschedule mode ($reschedule_cb = coderef)
		559
		560	In this mode $interval and $at are both being ignored. Instead, each
		561	time the periodic watcher gets scheduled, the reschedule callback
		562	($reschedule_cb) will be called with the watcher as first, and the current
		563	time as second argument.
		564
		565	I<This callback MUST NOT stop or destroy this or any other periodic
		566	watcher, ever>. If you need to stop it, return 1e30 and stop it
		567	afterwards.
		568
		569	It must return the next time to trigger, based on the passed time value
		570	(that is, the lowest time value larger than to the second argument). It
		571	will usually be called just before the callback will be triggered, but
		572	might be called at other times, too.
		573
		574	This can be used to create very complex timers, such as a timer that
		575	triggers on each midnight, local time (actually 24 hours after the last
		576	midnight, to keep the example simple. If you know a way to do it correctly
		577	in about the same space (without requiring elaborate modules), drop me a
		578	note :):
		579
		580	my $daily = EV::periodic 0, 0, sub {
		581	my ($w, $now) = @_;
		582
		583	use Time::Local ();
		584	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		585	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		586	}, sub {
		587	print "it's midnight or likely shortly after, now\n";
		588	};
		589
		590	=back
		591
163	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	592	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
164		593
		594	=item $w->set ($at, $interval, $reschedule_cb)
		595
		596	Reconfigures the watcher, see the constructor above for details. Can be called at
		597	any time.
		598
		599	=item $w->again
		600
		601	Simply stops and starts the watcher again.
		602
		603	=item $time = $w->at
		604
		605	Return the time that the watcher is expected to trigger next.
		606
		607	=back
		608
		609
		610	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		611
		612	=over 4
		613
165	=item my $w = EV::signal $signum, $callback	614	=item $w = EV::signal $signal, $callback
166		615
167	=item my $w = EV::signal_ns $signum, $callback	616	=item $w = EV::signal_ns $signal, $callback
168		617
169	Call the callback when signal $signum is received.	618	Call the callback when $signal is received (the signal can be specified by
		619	number or by name, just as with C<kill> or C<%SIG>).
170		620
		621	EV will grab the signal for the process (the kernel only allows one
		622	component to receive a signal at a time) when you start a signal watcher,
		623	and removes it again when you stop it. Perl does the same when you
		624	add/remove callbacks to C<%SIG>, so watch out.
		625
		626	You can have as many signal watchers per signal as you want.
		627
171	The C<signal_ns> variant doesn't add/start the newly created watcher.	628	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
172		629
173	=back	630	=item $w->set ($signal)
174		631
175	=head1 THE EV::Event CLASS	632	Reconfigures the watcher, see the constructor above for details. Can be
		633	called at any time.
176		634
177	All EV functions creating an event watcher (designated by C<my $w =>	635	=item $current_signum = $w->signal
178	above) support the following methods on the returned watcher object:
179		636
180	=over 4	637	=item $old_signum = $w->signal ($new_signal)
181		638
182	=item $w->add ($timeout)	639	Returns the previously set signal (always as a number not name) and
		640	optionally set a new one.
183		641
184	Stops and (re-)starts the event watcher, setting the optional timeout to	642	=back
185	the given value, or clearing the timeout if none is given.
186		643
		644
		645	=head3 CHILD WATCHERS - watch out for process status changes
		646
		647	=over 4
		648
		649	=item $w = EV::child $pid, $trace, $callback
		650
		651	=item $w = EV::child_ns $pid, $trace, $callback
		652
		653	=item $w = $loop->child ($pid, $trace, $callback)
		654
		655	=item $w = $loop->child_ns ($pid, $trace, $callback)
		656
		657	Call the callback when a status change for pid C<$pid> (or any pid
		658	if C<$pid> is 0) has been received (a status change happens when the
		659	process terminates or is killed, or, when trace is true, additionally when
		660	it is stopped or continued). More precisely: when the process receives
		661	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		662	changed/zombie children and call the callback.
		663
		664	It is valid (and fully supported) to install a child watcher after a child
		665	has exited but before the event loop has started its next iteration (for
		666	example, first you C<fork>, then the new child process might exit, and
		667	only then do you install a child watcher in the parent for the new pid).
		668
		669	You can access both exit (or tracing) status and pid by using the
		670	C<rstatus> and C<rpid> methods on the watcher object.
		671
		672	You can have as many pid watchers per pid as you want, they will all be
		673	called.
		674
		675	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		676
		677	=item $w->set ($pid, $trace)
		678
		679	Reconfigures the watcher, see the constructor above for details. Can be called at
		680	any time.
		681
		682	=item $current_pid = $w->pid
		683
		684	Returns the previously set process id and optionally set a new one.
		685
		686	=item $exit_status = $w->rstatus
		687
		688	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		689	in perlfunc).
		690
		691	=item $pid = $w->rpid
		692
		693	Return the pid of the awaited child (useful when you have installed a
		694	watcher for all pids).
		695
		696	=back
		697
		698
		699	=head3 STAT WATCHERS - did the file attributes just change?
		700
		701	=over 4
		702
		703	=item $w = EV::stat $path, $interval, $callback
		704
		705	=item $w = EV::stat_ns $path, $interval, $callback
		706
		707	=item $w = $loop->stat ($path, $interval, $callback)
		708
		709	=item $w = $loop->stat_ns ($path, $interval, $callback)
		710
		711	Call the callback when a file status change has been detected on
		712	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		713	to "path does not exist" is a status change like any other.
		714
		715	The C<$interval> is a recommended polling interval for systems where
		716	OS-supported change notifications don't exist or are not supported. If
		717	you use C<0> then an unspecified default is used (which is highly
		718	recommended!), which is to be expected to be around five seconds usually.
		719
		720	This watcher type is not meant for massive numbers of stat watchers,
		721	as even with OS-supported change notifications, this can be
		722	resource-intensive.
		723
		724	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		725
187	=item $w->start	726	=item ... = $w->stat
188		727
189	Stops and (re-)starts the event watcher without touching the timeout.	728	This call is very similar to the perl C<stat> built-in: It stats (using
		729	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		730	well as EV's idea of the current stat values) to the values found.
190		731
191	=item $w->del	732	In scalar context, a boolean is return indicating success or failure of
		733	the stat. In list context, the same 13-value list as with stat is returned
		734	(except that the blksize and blocks fields are not reliable).
192		735
193	=item $w->stop	736	In the case of an error, errno is set to C<ENOENT> (regardless of the
		737	actual error value) and the C<nlink> value is forced to zero (if the stat
		738	was successful then nlink is guaranteed to be non-zero).
194		739
195	Stop the event watcher if it was started.	740	See also the next two entries for more info.
196		741
197	=item $current_callback = $w->cb	742	=item ... = $w->attr
198		743
199	=item $old_callback = $w->cb ($new_callback)	744	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		745	the values most recently detected by EV. See the next entry for more info.
200		746
		747	=item ... = $w->prev
		748
		749	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		750	the previous set of values, before the change.
		751
		752	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		753	to the values found I<before> a change was detected, while C<< $w->attr >>
		754	returns the values found leading to the change detection. The difference (if any)
		755	between C<prev> and C<attr> is what triggered the callback.
		756
		757	If you did something to the filesystem object and do not want to trigger
		758	yet another change, you can call C<stat> to update EV's idea of what the
		759	current attributes are.
		760
		761	=item $w->set ($path, $interval)
		762
		763	Reconfigures the watcher, see the constructor above for details. Can be
		764	called at any time.
		765
		766	=item $current_path = $w->path
		767
		768	=item $old_path = $w->path ($new_path)
		769
201	Return the previously set callback and optionally set a new one.	770	Returns the previously set path and optionally set a new one.
202		771
203	=item $current_fh = $w->fh	772	=item $current_interval = $w->interval
204		773
205	=item $old_fh = $w->fh ($new_fh)	774	=item $old_interval = $w->interval ($new_interval)
206		775
207	Returns the previously set filehandle and optionally set a new one.
208
209	=item $current_eventmask = $w->events
210
211	=item $old_eventmask = $w->events ($new_eventmask)
212
213	Returns the previously set event mask and optionally set a new one.	776	Returns the previously set interval and optionally set a new one. Can be
		777	used to query the actual interval used.
214		778
215	=item $w->timeout ($after, $repeat)
216
217	Resets the timeout (see C<EV::timer> for details).
218
219	=item $w->timeout_abs ($at, $interval)
220
221	Resets the timeout (see C<EV::timer_abs> for details).
222
223	=item $w->priority_set ($priority)
224
225	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
226
227	=back	779	=back
228		780
229	=head1 BUGS
230		781
231	Lots. Libevent itself isn't well tested and rather buggy, and this module	782	=head3 IDLE WATCHERS - when you've got nothing better to do...
232	is quite new at the moment.
233		783
234	Please note that the epoll method is not, in general, reliable in programs	784	=over 4
235	that use fork (even if no libveent calls are being made in the forked
236	process). If your program behaves erratically, try setting the environment
237	variable C<EVENT_NOEPOLL> first when running the program.
238		785
239	In general, if you fork, then you can only use the EV module in one of the	786	=item $w = EV::idle $callback
240	children.	787
		788	=item $w = EV::idle_ns $callback
		789
		790	=item $w = $loop->idle ($callback)
		791
		792	=item $w = $loop->idle_ns ($callback)
		793
		794	Call the callback when there are no other pending watchers of the same or
		795	higher priority (excluding check, prepare and other idle watchers of the
		796	same or lower priority, of course). They are called idle watchers because
		797	when the watcher is the highest priority pending event in the process, the
		798	process is considered to be idle at that priority.
		799
		800	If you want a watcher that is only ever called when I<no> other events are
		801	outstanding you have to set the priority to C<EV::MINPRI>.
		802
		803	The process will not block as long as any idle watchers are active, and
		804	they will be called repeatedly until stopped.
		805
		806	For example, if you have idle watchers at priority C<0> and C<1>, and
		807	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		808	and the I/O watcher will always run when ready. Only when the idle watcher
		809	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		810	pending with the C<0>-priority idle watcher be invoked.
		811
		812	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		813
		814	=back
		815
		816
		817	=head3 PREPARE WATCHERS - customise your event loop!
		818
		819	=over 4
		820
		821	=item $w = EV::prepare $callback
		822
		823	=item $w = EV::prepare_ns $callback
		824
		825	=item $w = $loop->prepare ($callback)
		826
		827	=item $w = $loop->prepare_ns ($callback)
		828
		829	Call the callback just before the process would block. You can still
		830	create/modify any watchers at this point.
		831
		832	See the EV::check watcher, below, for explanations and an example.
		833
		834	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		835
		836	=back
		837
		838
		839	=head3 CHECK WATCHERS - customise your event loop even more!
		840
		841	=over 4
		842
		843	=item $w = EV::check $callback
		844
		845	=item $w = EV::check_ns $callback
		846
		847	=item $w = $loop->check ($callback)
		848
		849	=item $w = $loop->check_ns ($callback)
		850
		851	Call the callback just after the process wakes up again (after it has
		852	gathered events), but before any other callbacks have been invoked.
		853
		854	This is used to integrate other event-based software into the EV
		855	mainloop: You register a prepare callback and in there, you create io and
		856	timer watchers as required by the other software. Here is a real-world
		857	example of integrating Net::SNMP (with some details left out):
		858
		859	our @snmp_watcher;
		860
		861	our $snmp_prepare = EV::prepare sub {
		862	# do nothing unless active
		863	$dispatcher->{_event_queue_h}
		864	or return;
		865
		866	# make the dispatcher handle any outstanding stuff
		867	... not shown
		868
		869	# create an I/O watcher for each and every socket
		870	@snmp_watcher = (
		871	(map { EV::io $_, EV::READ, sub { } }
		872	keys %{ $dispatcher->{_descriptors} }),
		873
		874	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		875	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		876	0, sub { },
		877	);
		878	};
		879
		880	The callbacks are irrelevant (and are not even being called), the
		881	only purpose of those watchers is to wake up the process as soon as
		882	one of those events occurs (socket readable, or timer timed out). The
		883	corresponding EV::check watcher will then clean up:
		884
		885	our $snmp_check = EV::check sub {
		886	# destroy all watchers
		887	@snmp_watcher = ();
		888
		889	# make the dispatcher handle any new stuff
		890	... not shown
		891	};
		892
		893	The callbacks of the created watchers will not be called as the watchers
		894	are destroyed before this cna happen (remember EV::check gets called
		895	first).
		896
		897	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		898
		899	=back
		900
		901
		902	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		903
		904	Fork watchers are called when a C<fork ()> was detected. The invocation
		905	is done before the event loop blocks next and before C<check> watchers
		906	are being called, and only in the child after the fork.
		907
		908	=over 4
		909
		910	=item $w = EV::fork $callback
		911
		912	=item $w = EV::fork_ns $callback
		913
		914	=item $w = $loop->fork ($callback)
		915
		916	=item $w = $loop->fork_ns ($callback)
		917
		918	Call the callback before the event loop is resumed in the child process
		919	after a fork.
		920
		921	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		922
		923	=back
		924
		925
		926	=head3 EMBED WATCHERS - when one backend isn't enough...
		927
		928	This is a rather advanced watcher type that lets you embed one event loop
		929	into another (currently only IO events are supported in the embedded
		930	loop, other types of watchers might be handled in a delayed or incorrect
		931	fashion and must not be used).
		932
		933	See the libev documentation at
		934	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		935	for more details.
		936
		937	In short, this watcher is most useful on BSD systems without working
		938	kqueue to still be able to handle a large number of sockets:
		939
		940	my $socket_loop;
		941
		942	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		943	if (
		944	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		945	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		946	) {
		947	# use kqueue for sockets
		948	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		949	}
		950
		951	# use the default loop otherwise
		952	$socket_loop \|\|= EV::default_loop;
		953
		954	=over 4
		955
		956	=item $w = EV::embed $otherloop, $callback
		957
		958	=item $w = EV::embed_ns $otherloop, $callback
		959
		960	=item $w = $loop->embed ($otherloop, $callback)
		961
		962	=item $w = $loop->embed_ns ($otherloop, $callback)
		963
		964	Call the callback when the embedded event loop (C<$otherloop>) has any
		965	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		966	this version of EV, which means the embedded event loop will be managed
		967	automatically.
		968
		969	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		970
		971	=back
		972
		973
		974	=head1 PERL SIGNALS
		975
		976	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		977	with EV is as the same as any other C library: Perl-signals will only be
		978	handled when Perl runs, which means your signal handler might be invoked
		979	only the next time an event callback is invoked.
		980
		981	The solution is to use EV signal watchers (see C<EV::signal>), which will
		982	ensure proper operations with regards to other event watchers.
		983
		984	If you cannot do this for whatever reason, you can also force a watcher
		985	to be called on every event loop iteration by installing a C<EV::check>
		986	watcher:
		987
		988	my $async_check = EV::check sub { };
		989
		990	This ensures that perl gets into control for a short time to handle any
		991	pending signals, and also ensures (slightly) slower overall operation.
		992
		993	=head1 THREADS
		994
		995	Threads are not supported by this module in any way. Perl pseudo-threads
		996	is evil stuff and must die. As soon as Perl gains real threads I will work
		997	on thread support for it.
		998
		999	=head1 FORK
		1000
		1001	Most of the "improved" event delivering mechanisms of modern operating
		1002	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1003	not supported and usually destructive). Libev makes it possible to work
		1004	around this by having a function that recreates the kernel state after
		1005	fork in the child.
		1006
		1007	On non-win32 platforms, this module requires the pthread_atfork
		1008	functionality to do this automatically for you. This function is quite
		1009	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1010	negligible, because everything the function currently does is set a flag
		1011	that is checked only when the event loop gets used the next time, so when
		1012	you do fork but not use EV, the overhead is minimal.
		1013
		1014	On win32, there is no notion of fork so all this doesn't apply, of course.
241		1015
242	=cut	1016	=cut
243		1017
244	our $DIED = sub {	1018	our $DIED = sub {
245	warn "EV: error in callback (ignoring): $@";	1019	warn "EV: error in callback (ignoring): $@";
246	};	1020	};
247		1021
248	our $NPRI = 4;	1022	default_loop
249	our $BASE = init;	1023	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
250	priority_init $NPRI;
251
252	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
253		1024
254	1;	1025	1;
255		1026
256	=head1 SEE ALSO	1027	=head1 SEE ALSO
257		1028
258	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1029	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
259	L<EV::AnyEvent>.	1030	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1031	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP).
260		1032
261	=head1 AUTHOR	1033	=head1 AUTHOR
262		1034
263	Marc Lehmann <schmorp@schmorp.de>	1035	Marc Lehmann <schmorp@schmorp.de>
264	http://home.schmorp.de/	1036	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.9 by root, Sun Oct 28 06:40:46 2007 UTC vs. Revision 1.83 by root, Mon Jan 28 12:24:05 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.9 by root, Sun Oct 28 06:40:46 2007 UTC vs.
Revision 1.83 by root, Mon Jan 28 12:24:05 2008 UTC