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

Comparing EV/EV.pm (file contents):
Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs.
Revision 1.74 by root, Fri Dec 21 05:30:25 2007 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 $w = EV::child 666, sub {
		41	my ($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://cvs.schmorp.de/libev/ev.html>) for more subtle details on
		62	watcher semantics or some discussion on the available backends, or how to
		63	force a specific backend with C<LIBEV_FLAGS>, or just about in any case
		64	because it has much more detailed information.
47		65
48	=cut	66	=cut
49		67
50	package EV;	68	package EV;
51		69
52	use strict;	70	use strict;
53		71
54	BEGIN {	72	BEGIN {
55	our $VERSION = '0.01';	73	our $VERSION = '2.0';
56	use XSLoader;	74	use XSLoader;
57	XSLoader::load "EV", $VERSION;	75	XSLoader::load "EV", $VERSION;
58	}	76	}
59		77
60	=head1 FUNCTIONAL INTERFACE	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";
61		90
62	=over 4	91	@EV::Loop::Default::ISA = "EV::Loop";
63		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 cna 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	=back
		132
		133
		134	=head1 BASIC INTERFACE
		135
		136	=over 4
		137
64	=item $EV::NPRI	138	=item $EV::DIED
65		139
66	How many priority levels are available.	140	Must contain a reference to a function that is called when a callback
		141	throws an exception (with $@ containing the error). The default prints an
		142	informative message and continues.
		143
		144	If this callback throws an exception it will be silently ignored.
		145
		146	=item $time = EV::time
		147
		148	Returns the current time in (fractional) seconds since the epoch.
67		149
68	=item $time = EV::now	150	=item $time = EV::now
69		151
70	Returns the time in (fractional) seconds since the epoch.	152	=item $time = $loop->now
71		153
72	=item $version = EV::version	154	Returns the time the last event loop iteration has been started. This
		155	is the time that (relative) timers are based on, and refering to it is
		156	usually faster then calling EV::time.
73		157
74	=item $method = EV::method	158	=item $backend = EV::backend
75		159
76	Return version string and event polling method used.	160	=item $backend = $loop->backend
77		161
78	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	162	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		163	or EV::METHOD_EPOLL).
79		164
80	=item EV::loopexit $after	165	=item EV::loop [$flags]
81		166
82	Exit any active loop or dispatch after C<$after> seconds or immediately if	167	=item $loop->loop ([$flags])
83	C<$after> is missing or zero.
84		168
85	=item EV::dispatch	169	Begin checking for events and calling callbacks. It returns when a
		170	callback calls EV::unloop.
86		171
87	Same as C<EV::loop 0>.	172	The $flags argument can be one of the following:
88		173
89	=item EV::event $callback	174	0 as above
		175	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		176	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
90		177
91	Creates a new event watcher waiting for nothing, calling the given callback.	178	=item EV::unloop [$how]
92		179
		180	=item $loop->unloop ([$how])
		181
		182	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		183	innermost call to EV::loop return.
		184
		185	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		186	fast as possible.
		187
		188	=item $count = EV::loop_count
		189
		190	=item $count = $loop->loop_count
		191
		192	Return the number of times the event loop has polled for new
		193	events. Sometiems useful as a generation counter.
		194
		195	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		196
		197	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		198
		199	This function rolls together an I/O and a timer watcher for a single
		200	one-shot event without the need for managing a watcher object.
		201
		202	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		203	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		204	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		205	you do not want to wait for some I/O event, specify C<undef> for
		206	C<$fh_or_undef> and C<0> for C<$events>).
		207
		208	If timeout is C<undef> or negative, then there will be no
		209	timeout. Otherwise a EV::timer with this value will be started.
		210
		211	When an error occurs or either the timeout or I/O watcher triggers, then
		212	the callback will be called with the received event set (in general
		213	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		214	C<EV::WRITE> and C<EV::TIMEOUT>).
		215
		216	EV::once doesn't return anything: the watchers stay active till either
		217	of them triggers, then they will be stopped and freed, and the callback
		218	invoked.
		219
		220	=item EV::feed_fd_event ($fd, $revents)
		221
		222	=item $loop->feed_fd_event ($fd, $revents)
		223
		224	Feed an event on a file descriptor into EV. EV will react to this call as
		225	if the readyness notifications specified by C<$revents> (a combination of
		226	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		227
		228	=item EV::feed_signal_event ($signal)
		229
		230	Feed a signal event into EV. EV will react to this call as if the signal
		231	specified by C<$signal> had occured.
		232
		233	=back
		234
		235
		236	=head1 WATCHER OBJECTS
		237
		238	A watcher is an object that gets created to record your interest in some
		239	event. For instance, if you want to wait for STDIN to become readable, you
		240	would create an EV::io watcher for that:
		241
		242	my $watcher = EV::io *STDIN, EV::READ, sub {
		243	my ($watcher, $revents) = @_;
		244	warn "yeah, STDIN should not be readable without blocking!\n"
		245	};
		246
		247	All watchers can be active (waiting for events) or inactive (paused). Only
		248	active watchers will have their callbacks invoked. All callbacks will be
		249	called with at least two arguments: the watcher and a bitmask of received
		250	events.
		251
		252	Each watcher type has its associated bit in revents, so you can use the
		253	same callback for multiple watchers. The event mask is named after the
		254	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		255	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		256	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		257	uses EV::TIMEOUT).
		258
		259	In the rare case where one wants to create a watcher but not start it at
		260	the same time, each constructor has a variant with a trailing C<_ns> in
		261	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		262
		263	Please note that a watcher will automatically be stopped when the watcher
		264	object is destroyed, so you I<need> to keep the watcher objects returned by
		265	the constructors.
		266
		267	Also, all methods changing some aspect of a watcher (->set, ->priority,
		268	->fh and so on) automatically stop and start it again if it is active,
		269	which means pending events get lost.
		270
		271	=head2 COMMON WATCHER METHODS
		272
		273	This section lists methods common to all watchers.
		274
		275	=over 4
		276
		277	=item $w->start
		278
		279	Starts a watcher if it isn't active already. Does nothing to an already
		280	active watcher. By default, all watchers start out in the active state
		281	(see the description of the C<_ns> variants if you need stopped watchers).
		282
		283	=item $w->stop
		284
		285	Stop a watcher if it is active. Also clear any pending events (events that
		286	have been received but that didn't yet result in a callback invocation),
		287	regardless of whether the watcher was active or not.
		288
		289	=item $bool = $w->is_active
		290
		291	Returns true if the watcher is active, false otherwise.
		292
		293	=item $current_data = $w->data
		294
		295	=item $old_data = $w->data ($new_data)
		296
		297	Queries a freely usable data scalar on the watcher and optionally changes
		298	it. This is a way to associate custom data with a watcher:
		299
		300	my $w = EV::timer 60, 0, sub {
		301	warn $_[0]->data;
		302	};
		303	$w->data ("print me!");
		304
		305	=item $current_cb = $w->cb
		306
		307	=item $old_cb = $w->cb ($new_cb)
		308
		309	Queries the callback on the watcher and optionally changes it. You can do
		310	this at any time without the watcher restarting.
		311
		312	=item $current_priority = $w->priority
		313
		314	=item $old_priority = $w->priority ($new_priority)
		315
		316	Queries the priority on the watcher and optionally changes it. Pending
		317	watchers with higher priority will be invoked first. The valid range of
		318	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		319	-2). If the priority is outside this range it will automatically be
		320	normalised to the nearest valid priority.
		321
		322	The default priority of any newly-created watcher is 0.
		323
		324	Note that the priority semantics have not yet been fleshed out and are
		325	subject to almost certain change.
		326
		327	=item $w->invoke ($revents)
		328
		329	Call the callback now with the given event mask.
		330
		331	=item $w->feed_event ($revents)
		332
		333	Feed some events on this watcher into EV. EV will react to this call as if
		334	the watcher had received the given C<$revents> mask.
		335
		336	=item $revents = $w->clear_pending
		337
		338	If the watcher is pending, this function returns clears its pending status
		339	and returns its C<$revents> bitset (as if its callback was invoked). If the
		340	watcher isn't pending it does nothing and returns C<0>.
		341
		342	=item $previous_state = $w->keepalive ($bool)
		343
		344	Normally, C<EV::loop> will return when there are no active watchers
		345	(which is a "deadlock" because no progress can be made anymore). This is
		346	convinient because it allows you to start your watchers (and your jobs),
		347	call C<EV::loop> once and when it returns you know that all your jobs are
		348	finished (or they forgot to register some watchers for their task :).
		349
		350	Sometimes, however, this gets in your way, for example when you the module
		351	that calls C<EV::loop> (usually the main program) is not the same module
		352	as a long-living watcher (for example a DNS client module written by
		353	somebody else even). Then you might want any outstanding requests to be
		354	handled, but you would not want to keep C<EV::loop> from returning just
		355	because you happen to have this long-running UDP port watcher.
		356
		357	In this case you can clear the keepalive status, which means that even
		358	though your watcher is active, it won't keep C<EV::loop> from returning.
		359
		360	The initial value for keepalive is true (enabled), and you cna change it
		361	any time.
		362
		363	Example: Register an I/O watcher for some UDP socket but do not keep the
		364	event loop from running just because of that watcher.
		365
		366	my $udp_socket = ...
		367	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		368	$1000udp_watcher->keepalive (0);
		369
		370	=item $loop = $w->loop
		371
		372	Return the loop that this watcher is attached to.
		373
		374	=back
		375
		376
		377	=head1 WATCHER TYPES
		378
		379	Each of the following subsections describes a single watcher type.
		380
		381	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		382
		383	=over 4
		384
93	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	385	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
94		386
95	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	387	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		388
		389	=item $w = $loop->io 8$fileno_or_fh, $eventmask, $callback)
		390
		391	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
96		392
97	As long as the returned watcher object is alive, call the C<$callback>	393	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	394	when at least one of events specified in C<$eventmask> occurs.
99	is disabled.
100		395
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:	396	The $eventmask can be one or more of these constants ORed together:
104		397
105	EV::READ wait until read() wouldn't block anymore	398	EV::READ wait until read() wouldn't block anymore
106	EV::WRITE wait until write() wouldn't block anymore	399	EV::WRITE wait until write() wouldn't block anymore
107	EV::PERSIST stay active after an event occured
108		400
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.	401	The C<io_ns> variant doesn't start (activate) the newly created watcher.
119		402
120	=item my $w = EV::timer_abs $at, $interval, $callback	403	=item $w->set ($fileno_or_fh, $eventmask)
121		404
122	=item my $w = EV::timer_abs_ns $at, $interval, $callback	405	Reconfigures the watcher, see the constructor above for details. Can be
123		406	called at any time.
124	Similar to EV::timer, but the time is given as an absolute point in time
125	(C<$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		407
178	=item $current_fh = $w->fh	408	=item $current_fh = $w->fh
179		409
180	=item $old_fh = $w->fh ($new_fh)	410	=item $old_fh = $w->fh ($new_fh)
181		411
185		415
186	=item $old_eventmask = $w->events ($new_eventmask)	416	=item $old_eventmask = $w->events ($new_eventmask)
187		417
188	Returns the previously set event mask and optionally set a new one.	418	Returns the previously set event mask and optionally set a new one.
189		419
		420	=back
		421
		422
		423	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		424
		425	=over 4
		426
		427	=item $w = EV::timer $after, $repeat, $callback
		428
		429	=item $w = EV::timer_ns $after, $repeat, $callback
		430
		431	=item $w = $loop->timer ($after, $repeat, $callback)
		432
		433	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		434
		435	Calls the callback after C<$after> seconds (which may be fractional). If
		436	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		437	value as $after) after the callback returns.
		438
		439	This means that the callback would be called roughly after C<$after>
		440	seconds, and then every C<$repeat> seconds. The timer does his best not
		441	to drift, but it will not invoke the timer more often then once per event
		442	loop iteration, and might drift in other cases. If that isn't acceptable,
		443	look at EV::periodic, which can provide long-term stable timers.
		444
		445	The timer is based on a monotonic clock, that is, if somebody is sitting
		446	in front of the machine while the timer is running and changes the system
		447	clock, the timer will nevertheless run (roughly) the same time.
		448
		449	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		450
190	=item $w->timeout ($after, $repeat)	451	=item $w->set ($after, $repeat)
191		452
192	Resets the timeout (see C<EV::timer> for details).	453	Reconfigures the watcher, see the constructor above for details. Can be called at
		454	any time.
193		455
		456	=item $w->again
		457
		458	Similar to the C<start> method, but has special semantics for repeating timers:
		459
		460	If the timer is active and non-repeating, it will be stopped.
		461
		462	If the timer is active and repeating, reset the timeout to occur
		463	C<$repeat> seconds after now.
		464
		465	If the timer is inactive and repeating, start it using the repeat value.
		466
		467	Otherwise do nothing.
		468
		469	This behaviour is useful when you have a timeout for some IO
		470	operation. You create a timer object with the same value for C<$after> and
		471	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		472	on the timeout.
		473
		474	=back
		475
		476
		477	=head3 PERIODIC WATCHERS - to cron or not to cron?
		478
		479	=over 4
		480
		481	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		482
		483	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		484
		485	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		486
		487	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		488
		489	Similar to EV::timer, but is not based on relative timeouts but on
		490	absolute times. Apart from creating "simple" timers that trigger "at" the
		491	specified time, it can also be used for non-drifting absolute timers and
		492	more complex, cron-like, setups that are not adversely affected by time
		493	jumps (i.e. when the system clock is changed by explicit date -s or other
		494	means such as ntpd). It is also the most complex watcher type in EV.
		495
		496	It has three distinct "modes":
		497
		498	=over 4
		499
		500	=item * absolute timer ($interval = $reschedule_cb = 0)
		501
		502	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		503	will not adjust when a time jump occurs, that is, if it is to be run
		504	at January 1st 2011 then it will run when the system time reaches or
		505	surpasses this time.
		506
		507	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		508
		509	In this mode the watcher will always be scheduled to time out at the
		510	next C<$at + N * $interval> time (for some integer N) and then repeat,
		511	regardless of any time jumps.
		512
		513	This can be used to create timers that do not drift with respect to system
		514	time:
		515
		516	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		517
		518	That doesn't mean there will always be 3600 seconds in between triggers,
		519	but only that the the clalback will be called when the system time shows a
		520	full hour (UTC).
		521
		522	Another way to think about it (for the mathematically inclined) is that
		523	EV::periodic will try to run the callback in this mode at the next
		524	possible time where C<$time = $at (mod $interval)>, regardless of any time
		525	jumps.
		526
		527	=item * manual reschedule mode ($reschedule_cb = coderef)
		528
		529	In this mode $interval and $at are both being ignored. Instead, each
		530	time the periodic watcher gets scheduled, the reschedule callback
		531	($reschedule_cb) will be called with the watcher as first, and the current
		532	time as second argument.
		533
		534	I<This callback MUST NOT stop or destroy this or any other periodic
		535	watcher, ever>. If you need to stop it, return 1e30 and stop it
		536	afterwards.
		537
		538	It must return the next time to trigger, based on the passed time value
		539	(that is, the lowest time value larger than to the second argument). It
		540	will usually be called just before the callback will be triggered, but
		541	might be called at other times, too.
		542
		543	This can be used to create very complex timers, such as a timer that
		544	triggers on each midnight, local time (actually 24 hours after the last
		545	midnight, to keep the example simple. If you know a way to do it correctly
		546	in about the same space (without requiring elaborate modules), drop me a
		547	note :):
		548
		549	my $daily = EV::periodic 0, 0, sub {
		550	my ($w, $now) = @_;
		551
		552	use Time::Local ();
		553	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		554	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		555	}, sub {
		556	print "it's midnight or likely shortly after, now\n";
		557	};
		558
		559	=back
		560
		561	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		562
		563	=item $w->set ($at, $interval, $reschedule_cb)
		564
		565	Reconfigures the watcher, see the constructor above for details. Can be called at
		566	any time.
		567
		568	=item $w->again
		569
		570	Simply stops and starts the watcher again.
		571
		572	=item $time = $w->at
		573
		574	Return the time that the watcher is expected to trigger next.
		575
		576	=back
		577
		578
		579	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		580
		581	=over 4
		582
		583	=item $w = EV::signal $signal, $callback
		584
		585	=item $w = EV::signal_ns $signal, $callback
		586
		587	Call the callback when $signal is received (the signal can be specified by
		588	number or by name, just as with C<kill> or C<%SIG>).
		589
		590	EV will grab the signal for the process (the kernel only allows one
		591	component to receive a signal at a time) when you start a signal watcher,
		592	and removes it again when you stop it. Perl does the same when you
		593	add/remove callbacks to C<%SIG>, so watch out.
		594
		595	You can have as many signal watchers per signal as you want.
		596
		597	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		598
		599	=item $w->set ($signal)
		600
		601	Reconfigures the watcher, see the constructor above for details. Can be
		602	called at any time.
		603
		604	=item $current_signum = $w->signal
		605
		606	=item $old_signum = $w->signal ($new_signal)
		607
		608	Returns the previously set signal (always as a number not name) and
		609	optionally set a new one.
		610
		611	=back
		612
		613
		614	=head3 CHILD WATCHERS - watch out for process status changes
		615
		616	=over 4
		617
		618	=item $w = EV::child $pid, $callback
		619
		620	=item $w = EV::child_ns $pid, $callback
		621
		622	=item $w = $loop->child ($pid, $callback)
		623
		624	=item $w = $loop->child_ns ($pid, $callback)
		625
		626	Call the callback when a status change for pid C<$pid> (or any pid if
		627	C<$pid> is 0) has been received. More precisely: when the process receives
		628	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		629	changed/zombie children and call the callback.
		630
		631	It is valid (and fully supported) to install a child watcher after a child
		632	has exited but before the event loop has started its next iteration (for
		633	example, first you C<fork>, then the new child process might exit, and
		634	only then do you install a child watcher in the parent for the new pid).
		635
		636	You can access both exit (or tracing) status and pid by using the
		637	C<rstatus> and C<rpid> methods on the watcher object.
		638
		639	You can have as many pid watchers per pid as you want, they will all be
		640	called.
		641
		642	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		643
		644	=item $w->set ($pid)
		645
		646	Reconfigures the watcher, see the constructor above for details. Can be called at
		647	any time.
		648
		649	=item $current_pid = $w->pid
		650
		651	=item $old_pid = $w->pid ($new_pid)
		652
		653	Returns the previously set process id and optionally set a new one.
		654
		655	=item $exit_status = $w->rstatus
		656
		657	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		658	in perlfunc).
		659
		660	=item $pid = $w->rpid
		661
		662	Return the pid of the awaited child (useful when you have installed a
		663	watcher for all pids).
		664
		665	=back
		666
		667
		668	=head3 STAT WATCHERS - did the file attributes just change?
		669
		670	=over 4
		671
		672	=item $w = EV::stat $path, $interval, $callback
		673
		674	=item $w = EV::stat_ns $path, $interval, $callback
		675
		676	=item $w = $loop->stat ($path, $interval, $callback)
		677
		678	=item $w = $loop->stat_ns ($path, $interval, $callback)
		679
		680	Call the callback when a file status change has been detected on
		681	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		682	to "path does not exist" is a status change like any other.
		683
		684	The C<$interval> is a recommended polling interval for systems where
		685	OS-supported change notifications don't exist or are not supported. If
		686	you use C<0> then an unspecified default is used (which is highly
		687	recommended!), which is to be expected to be around five seconds usually.
		688
		689	This watcher type is not meant for massive numbers of stat watchers,
		690	as even with OS-supported change notifications, this can be
		691	resource-intensive.
		692
		693	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		694
		695	=item ... = $w->stat
		696
		697	This call is very similar to the perl C<stat> built-in: It stats (using
		698	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		699	well as EV's idea of the current stat values) to the values found.
		700
		701	In scalar context, a boolean is return indicating success or failure of
		702	the stat. In list context, the same 13-value list as with stat is returned
		703	(except that the blksize and blocks fields are not reliable).
		704
		705	In the case of an error, errno is set to C<ENOENT> (regardless of the
		706	actual error value) and the C<nlink> value is forced to zero (if the stat
		707	was successful then nlink is guaranteed to be non-zero).
		708
		709	See also the next two entries for more info.
		710
		711	=item ... = $w->attr
		712
		713	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		714	the values most recently detected by EV. See the next entry for more info.
		715
		716	=item ... = $w->prev
		717
		718	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		719	the previous set of values, before the change.
		720
		721	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		722	to the values found I<before> a change was detected, while C<< $w->attr >>
		723	returns the values found leading to the change detection. The difference (if any)
		724	between C<prev> and C<attr> is what triggered the callback.
		725
		726	If you did something to the filesystem object and do not want to trigger
		727	yet another change, you can call C<stat> to update EV's idea of what the
		728	current attributes are.
		729
194	=item $w->timeout_abs ($at, $interval)	730	=item $w->set ($path, $interval)
195		731
196	Resets the timeout (see C<EV::timer_abs> for details).	732	Reconfigures the watcher, see the constructor above for details. Can be
		733	called at any time.
197		734
198	=item $w->priority_set ($priority)	735	=item $current_path = $w->path
199		736
200	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	737	=item $old_path = $w->path ($new_path)
201		738
202	=back	739	Returns the previously set path and optionally set a new one.
203		740
204	=head1 BUGS	741	=item $current_interval = $w->interval
205		742
206	Lots. Libevent itself isn't well tested and rather buggy, and this module	743	=item $old_interval = $w->interval ($new_interval)
207	is quite new at the moment.	744
		745	Returns the previously set interval and optionally set a new one. Can be
		746	used to query the actual interval used.
		747
		748	=back
		749
		750
		751	=head3 IDLE WATCHERS - when you've got nothing better to do...
		752
		753	=over 4
		754
		755	=item $w = EV::idle $callback
		756
		757	=item $w = EV::idle_ns $callback
		758
		759	=item $w = $loop->idle ($callback)
		760
		761	=item $w = $loop->idle_ns ($callback)
		762
		763	Call the callback when there are no other pending watchers of the same or
		764	higher priority (excluding check, prepare and other idle watchers of the
		765	same or lower priority, of course). They are called idle watchers because
		766	when the watcher is the highest priority pending event in the process, the
		767	process is considered to be idle at that priority.
		768
		769	If you want a watcher that is only ever called when I<no> other events are
		770	outstanding you have to set the priority to C<EV::MINPRI>.
		771
		772	The process will not block as long as any idle watchers are active, and
		773	they will be called repeatedly until stopped.
		774
		775	For example, if you have idle watchers at priority C<0> and C<1>, and
		776	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		777	and the I/O watcher will always run when ready. Only when the idle watcher
		778	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		779	pending with the C<0>-priority idle watcher be invoked.
		780
		781	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		782
		783	=back
		784
		785
		786	=head3 PREPARE WATCHERS - customise your event loop!
		787
		788	=over 4
		789
		790	=item $w = EV::prepare $callback
		791
		792	=item $w = EV::prepare_ns $callback
		793
		794	=item $w = $loop->prepare ($callback)
		795
		796	=item $w = $loop->prepare_ns 8$callback)
		797
		798	Call the callback just before the process would block. You can still
		799	create/modify any watchers at this point.
		800
		801	See the EV::check watcher, below, for explanations and an example.
		802
		803	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		804
		805	=back
		806
		807
		808	=head3 CHECK WATCHERS - customise your event loop even more!
		809
		810	=over 4
		811
		812	=item $w = EV::check $callback
		813
		814	=item $w = EV::check_ns $callback
		815
		816	=item $w = $loop->check ($callback)
		817
		818	=item $w = $loop->check_ns ($callback)
		819
		820	Call the callback just after the process wakes up again (after it has
		821	gathered events), but before any other callbacks have been invoked.
		822
		823	This is used to integrate other event-based software into the EV
		824	mainloop: You register a prepare callback and in there, you create io and
		825	timer watchers as required by the other software. Here is a real-world
		826	example of integrating Net::SNMP (with some details left out):
		827
		828	our @snmp_watcher;
		829
		830	our $snmp_prepare = EV::prepare sub {
		831	# do nothing unless active
		832	$dispatcher->{_event_queue_h}
		833	or return;
		834
		835	# make the dispatcher handle any outstanding stuff
		836	... not shown
		837
		838	# create an I/O watcher for each and every socket
		839	@snmp_watcher = (
		840	(map { EV::io $_, EV::READ, sub { } }
		841	keys %{ $dispatcher->{_descriptors} }),
		842
		843	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		844	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		845	0, sub { },
		846	);
		847	};
		848
		849	The callbacks are irrelevant (and are not even being called), the
		850	only purpose of those watchers is to wake up the process as soon as
		851	one of those events occurs (socket readable, or timer timed out). The
		852	corresponding EV::check watcher will then clean up:
		853
		854	our $snmp_check = EV::check sub {
		855	# destroy all watchers
		856	@snmp_watcher = ();
		857
		858	# make the dispatcher handle any new stuff
		859	... not shown
		860	};
		861
		862	The callbacks of the created watchers will not be called as the watchers
		863	are destroyed before this cna happen (remember EV::check gets called
		864	first).
		865
		866	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		867
		868	=back
		869
		870
		871	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		872
		873	Fork watchers are called when a C<fork ()> was detected. The invocation
		874	is done before the event loop blocks next and before C<check> watchers
		875	are being called, and only in the child after the fork.
		876
		877	=over 4
		878
		879	=item $w = EV::fork $callback
		880
		881	=item $w = EV::fork_ns $callback
		882
		883	=item $w = $loop->fork ($callback)
		884
		885	=item $w = $loop->fork_ns ($callback)
		886
		887	Call the callback before the event loop is resumed in the child process
		888	after a fork.
		889
		890	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		891
		892	=back
		893
		894
		895	=head1 PERL SIGNALS
		896
		897	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		898	with EV is as the same as any other C library: Perl-signals will only be
		899	handled when Perl runs, which means your signal handler might be invoked
		900	only the next time an event callback is invoked.
		901
		902	The solution is to use EV signal watchers (see C<EV::signal>), which will
		903	ensure proper operations with regards to other event watchers.
		904
		905	If you cannot do this for whatever reason, you can also force a watcher
		906	to be called on every event loop iteration by installing a C<EV::check>
		907	watcher:
		908
		909	my $async_check = EV::check sub { };
		910
		911	This ensures that perl shortly gets into control for a short time, and
		912	also ensures slower overall operation.
		913
		914	=head1 THREADS
		915
		916	Threads are not supported by this module in any way. Perl pseudo-threads
		917	is evil stuff and must die. As soon as Perl gains real threads I will work
		918	on thread support for it.
		919
		920	=head1 FORK
		921
		922	Most of the "improved" event delivering mechanisms of modern operating
		923	systems have quite a few problems with fork(2) (to put it bluntly: it is
		924	not supported and usually destructive). Libev makes it possible to work
		925	around this by having a function that recreates the kernel state after
		926	fork in the child.
		927
		928	On non-win32 platforms, this module requires the pthread_atfork
		929	functionality to do this automatically for you. This function is quite
		930	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		931	negligible, because everything the function currently does is set a flag
		932	that is checked only when the event loop gets used the next time, so when
		933	you do fork but not use EV, the overhead is minimal.
		934
		935	On win32, there is no notion of fork so all this doesn't apply, of course.
208		936
209	=cut	937	=cut
210		938
211	our $NPRI = 4;	939	our $DIED = sub {
212	our $BASE = init;	940	warn "EV: error in callback (ignoring): $@";
213	priority_init $NPRI;	941	};
214		942
215	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];	943	default_loop
		944	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
216		945
217	1;	946	1;
218		947
219	=head1 SEE ALSO	948	=head1 SEE ALSO
220		949
221	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	950	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
		951	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		952	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP).
222		953
223	=head1 AUTHOR	954	=head1 AUTHOR
224		955
225	Marc Lehmann <schmorp@schmorp.de>	956	Marc Lehmann <schmorp@schmorp.de>
226	http://home.schmorp.de/	957	http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing EV/EV.pm (file contents): Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs. Revision 1.74 by root, Fri Dec 21 05:30:25 2007 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs.
Revision 1.74 by root, Fri Dec 21 05:30:25 2007 UTC