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

Comparing EV/EV.pm (file contents):
Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs.
Revision 1.103 by root, Thu Oct 2 07:49:09 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothign received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}	30	};
		31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
34	};	36	};
35	$w->timeout (10);	37
36		38	# CHILD/PID STATUS CHANGES
		39
		40	my $w = EV::child 666, 0, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
		44
		45	# STAT CHANGES
		46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
		49	};
		50
37	# MAINLOOP	51	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		55
43	=head1 DESCRIPTION	56	=head1 DESCRIPTION
44		57
45	This module provides an interface to libevent	58	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
47	yourself with its documentation and source code to be able to use this	60	below is comprehensive, one might also consult the documentation of libev
48	module fully.	61	itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
		62	subtle details on watcher semantics or some discussion on the available
		63	backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
		64	about in any case because it has much more detailed information.
49		65
50	Please note thta this module disables the libevent EPOLL method by	66	This module is very fast and scalable. It is actually so fast that you
51	default, see BUGS, below, if you need to enable it.	67	can use it through the L<AnyEvent> module, stay portable to other event
		68	loops (if you don't rely on any watcher types not available through it)
		69	and still be faster than with any other event loop currently supported in
		70	Perl.
52		71
53	=cut	72	=cut
54		73
55	package EV;	74	package EV;
56		75
		76	no warnings;
57	use strict;	77	use strict;
58		78
59	BEGIN {	79	BEGIN {
60	our $VERSION = '0.01';	80	our $VERSION = '3.44';
61	use XSLoader;	81	use XSLoader;
62	XSLoader::load "EV", $VERSION;	82	XSLoader::load "EV", $VERSION;
63	}	83	}
64		84
65	=head1 FUNCTIONAL INTERFACE	85	@EV::IO::ISA =
		86	@EV::Timer::ISA =
		87	@EV::Periodic::ISA =
		88	@EV::Signal::ISA =
		89	@EV::Child::ISA =
		90	@EV::Stat::ISA =
		91	@EV::Idle::ISA =
		92	@EV::Prepare::ISA =
		93	@EV::Check::ISA =
		94	@EV::Embed::ISA =
		95	@EV::Fork::ISA =
		96	@EV::Async::ISA =
		97	"EV::Watcher";
66		98
67	=over 4	99	@EV::Loop::Default::ISA = "EV::Loop";
68		100
		101	=head1 EVENT LOOPS
		102
		103	EV supports multiple event loops: There is a single "default event loop"
		104	that can handle everything including signals and child watchers, and any
		105	number of "dynamic event loops" that can use different backends (with
		106	various limitations), but no child and signal watchers.
		107
		108	You do not have to do anything to create the default event loop: When
		109	the module is loaded a suitable backend is selected on the premise of
		110	selecting a working backend (which for example rules out kqueue on most
		111	BSDs). Modules should, unless they have "special needs" always use the
		112	default loop as this is fastest (perl-wise), best supported by other
		113	modules (e.g. AnyEvent or Coro) and most portable event loop.
		114
		115	For specific programs you can create additional event loops dynamically.
		116
		117	If you want to take avdantage of kqueue (which often works properly for
		118	sockets only) even though the default loop doesn't enable it, you can
		119	I<embed> a kqueue loop into the default loop: running the default loop
		120	will then also service the kqueue loop to some extent. See the example in
		121	the section about embed watchers for an example on how to achieve that.
		122
		123	=over 4
		124
		125	=item $loop = new EV::loop [$flags]
		126
		127	Create a new event loop as per the specified flags. Please refer to the
		128	C<ev_loop_new ()> function description in the libev documentation
		129	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		130	for more info.
		131
		132	The loop will automatically be destroyed when it is no longer referenced
		133	by any watcher and the loop object goes out of scope.
		134
		135	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		136	is recommended, as only the default event loop is protected by this
		137	module. If you I<are> embedding this loop in the default loop, this is not
		138	necessary, as C<EV::embed> automatically does the right thing on fork.
		139
		140	=item $loop->loop_fork
		141
		142	Must be called after a fork in the child, before entering or continuing
		143	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		144	this function automatically, at some performance loss (refer to the libev
		145	documentation).
		146
		147	=item $loop->loop_verify
		148
		149	Calls C<ev_verify> to make internal consistency checks (for debugging
		150	libev) and abort the program if any data structures were found to be
		151	corrupted.
		152
		153	=item $loop = EV::default_loop [$flags]
		154
		155	Return the default loop (which is a singleton object). Since this module
		156	already creates the default loop with default flags, specifying flags here
		157	will not have any effect unless you destroy the default loop first, which
		158	isn't supported. So in short: don't do it, and if you break it, you get to
		159	keep the pieces.
		160
		161	=back
		162
		163
		164	=head1 BASIC INTERFACE
		165
		166	=over 4
		167
69	=item $EV::NPRI	168	=item $EV::DIED
70		169
71	How many priority levels are available.	170	Must contain a reference to a function that is called when a callback
		171	throws an exception (with $@ containing the error). The default prints an
		172	informative message and continues.
		173
		174	If this callback throws an exception it will be silently ignored.
		175
		176	=item $flags = EV::supported_backends
		177
		178	=item $flags = EV::recommended_backends
		179
		180	=item $flags = EV::embeddable_backends
		181
		182	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		183	instance of EV, the set of recommended backends (supposed to be good) for
		184	this platform and the set of embeddable backends (see EMBED WATCHERS).
		185
		186	=item EV::sleep $seconds
		187
		188	Block the process for the given number of (fractional) seconds.
		189
		190	=item $time = EV::time
		191
		192	Returns the current time in (fractional) seconds since the epoch.
72		193
73	=item $time = EV::now	194	=item $time = EV::now
74		195
75	Returns the time in (fractional) seconds since the epoch.	196	=item $time = $loop->now
76		197
77	=item $version = EV::version	198	Returns the time the last event loop iteration has been started. This
		199	is the time that (relative) timers are based on, and refering to it is
		200	usually faster then calling EV::time.
78		201
79	=item $method = EV::method	202	=item $backend = EV::backend
80		203
81	Return version string and event polling method used.	204	=item $backend = $loop->backend
82		205
83	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	206	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		207	or EV::METHOD_EPOLL).
84		208
85	=item EV::loopexit $after	209	=item EV::loop [$flags]
86		210
87	Exit any active loop or dispatch after C<$after> seconds or immediately if	211	=item $loop->loop ([$flags])
88	C<$after> is missing or zero.
89		212
90	=item EV::dispatch	213	Begin checking for events and calling callbacks. It returns when a
		214	callback calls EV::unloop.
91		215
92	Same as C<EV::loop 0>.	216	The $flags argument can be one of the following:
93		217
94	=item EV::event $callback	218	0 as above
		219	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		220	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
95		221
96	Creates a new event watcher waiting for nothing, calling the given callback.	222	=item EV::unloop [$how]
97		223
		224	=item $loop->unloop ([$how])
		225
		226	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		227	innermost call to EV::loop return.
		228
		229	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		230	fast as possible.
		231
		232	=item $count = EV::loop_count
		233
		234	=item $count = $loop->loop_count
		235
		236	Return the number of times the event loop has polled for new
		237	events. Sometiems useful as a generation counter.
		238
		239	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		240
		241	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		242
		243	This function rolls together an I/O and a timer watcher for a single
		244	one-shot event without the need for managing a watcher object.
		245
		246	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		247	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		248	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		249	you do not want to wait for some I/O event, specify C<undef> for
		250	C<$fh_or_undef> and C<0> for C<$events>).
		251
		252	If timeout is C<undef> or negative, then there will be no
		253	timeout. Otherwise a EV::timer with this value will be started.
		254
		255	When an error occurs or either the timeout or I/O watcher triggers, then
		256	the callback will be called with the received event set (in general
		257	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		258	C<EV::WRITE> and C<EV::TIMEOUT>).
		259
		260	EV::once doesn't return anything: the watchers stay active till either
		261	of them triggers, then they will be stopped and freed, and the callback
		262	invoked.
		263
		264	=item EV::feed_fd_event ($fd, $revents)
		265
		266	=item $loop->feed_fd_event ($fd, $revents)
		267
		268	Feed an event on a file descriptor into EV. EV will react to this call as
		269	if the readyness notifications specified by C<$revents> (a combination of
		270	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		271
		272	=item EV::feed_signal_event ($signal)
		273
		274	Feed a signal event into EV. EV will react to this call as if the signal
		275	specified by C<$signal> had occured.
		276
		277	=item EV::set_io_collect_interval $time
		278
		279	=item $loop->set_io_collect_interval ($time)
		280
		281	=item EV::set_timeout_collect_interval $time
		282
		283	=item $loop->set_timeout_collect_interval ($time)
		284
		285	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		286	wait interval for timer events. See the libev documentation at
		287	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		288	a more detailed discussion.
		289
		290	=back
		291
		292
		293	=head1 WATCHER OBJECTS
		294
		295	A watcher is an object that gets created to record your interest in some
		296	event. For instance, if you want to wait for STDIN to become readable, you
		297	would create an EV::io watcher for that:
		298
		299	my $watcher = EV::io *STDIN, EV::READ, sub {
		300	my ($watcher, $revents) = @_;
		301	warn "yeah, STDIN should now be readable without blocking!\n"
		302	};
		303
		304	All watchers can be active (waiting for events) or inactive (paused). Only
		305	active watchers will have their callbacks invoked. All callbacks will be
		306	called with at least two arguments: the watcher and a bitmask of received
		307	events.
		308
		309	Each watcher type has its associated bit in revents, so you can use the
		310	same callback for multiple watchers. The event mask is named after the
		311	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		312	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		313	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		314	uses EV::TIMEOUT).
		315
		316	In the rare case where one wants to create a watcher but not start it at
		317	the same time, each constructor has a variant with a trailing C<_ns> in
		318	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		319
		320	Please note that a watcher will automatically be stopped when the watcher
		321	object is destroyed, so you I<need> to keep the watcher objects returned by
		322	the constructors.
		323
		324	Also, all methods changing some aspect of a watcher (->set, ->priority,
		325	->fh and so on) automatically stop and start it again if it is active,
		326	which means pending events get lost.
		327
		328	=head2 COMMON WATCHER METHODS
		329
		330	This section lists methods common to all watchers.
		331
		332	=over 4
		333
		334	=item $w->start
		335
		336	Starts a watcher if it isn't active already. Does nothing to an already
		337	active watcher. By default, all watchers start out in the active state
		338	(see the description of the C<_ns> variants if you need stopped watchers).
		339
		340	=item $w->stop
		341
		342	Stop a watcher if it is active. Also clear any pending events (events that
		343	have been received but that didn't yet result in a callback invocation),
		344	regardless of whether the watcher was active or not.
		345
		346	=item $bool = $w->is_active
		347
		348	Returns true if the watcher is active, false otherwise.
		349
		350	=item $current_data = $w->data
		351
		352	=item $old_data = $w->data ($new_data)
		353
		354	Queries a freely usable data scalar on the watcher and optionally changes
		355	it. This is a way to associate custom data with a watcher:
		356
		357	my $w = EV::timer 60, 0, sub {
		358	warn $_[0]->data;
		359	};
		360	$w->data ("print me!");
		361
		362	=item $current_cb = $w->cb
		363
		364	=item $old_cb = $w->cb ($new_cb)
		365
		366	Queries the callback on the watcher and optionally changes it. You can do
		367	this at any time without the watcher restarting.
		368
		369	=item $current_priority = $w->priority
		370
		371	=item $old_priority = $w->priority ($new_priority)
		372
		373	Queries the priority on the watcher and optionally changes it. Pending
		374	watchers with higher priority will be invoked first. The valid range of
		375	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		376	-2). If the priority is outside this range it will automatically be
		377	normalised to the nearest valid priority.
		378
		379	The default priority of any newly-created watcher is 0.
		380
		381	Note that the priority semantics have not yet been fleshed out and are
		382	subject to almost certain change.
		383
		384	=item $w->invoke ($revents)
		385
		386	Call the callback now with the given event mask.
		387
		388	=item $w->feed_event ($revents)
		389
		390	Feed some events on this watcher into EV. EV will react to this call as if
		391	the watcher had received the given C<$revents> mask.
		392
		393	=item $revents = $w->clear_pending
		394
		395	If the watcher is pending, this function clears its pending status and
		396	returns its C<$revents> bitset (as if its callback was invoked). If the
		397	watcher isn't pending it does nothing and returns C<0>.
		398
		399	=item $previous_state = $w->keepalive ($bool)
		400
		401	Normally, C<EV::loop> will return when there are no active watchers
		402	(which is a "deadlock" because no progress can be made anymore). This is
		403	convinient because it allows you to start your watchers (and your jobs),
		404	call C<EV::loop> once and when it returns you know that all your jobs are
		405	finished (or they forgot to register some watchers for their task :).
		406
		407	Sometimes, however, this gets in your way, for example when the module
		408	that calls C<EV::loop> (usually the main program) is not the same module
		409	as a long-living watcher (for example a DNS client module written by
		410	somebody else even). Then you might want any outstanding requests to be
		411	handled, but you would not want to keep C<EV::loop> from returning just
		412	because you happen to have this long-running UDP port watcher.
		413
		414	In this case you can clear the keepalive status, which means that even
		415	though your watcher is active, it won't keep C<EV::loop> from returning.
		416
		417	The initial value for keepalive is true (enabled), and you cna change it
		418	any time.
		419
		420	Example: Register an I/O watcher for some UDP socket but do not keep the
		421	event loop from running just because of that watcher.
		422
		423	my $udp_socket = ...
		424	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		425	$udp_watcher->keepalive (0);
		426
		427	=item $loop = $w->loop
		428
		429	Return the loop that this watcher is attached to.
		430
		431	=back
		432
		433
		434	=head1 WATCHER TYPES
		435
		436	Each of the following subsections describes a single watcher type.
		437
		438	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		439
		440	=over 4
		441
98	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	442	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
99		443
100	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	444	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		445
		446	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		447
		448	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
101		449
102	As long as the returned watcher object is alive, call the C<$callback>	450	As long as the returned watcher object is alive, call the C<$callback>
103	when the events specified in C<$eventmask> happen. Initially, the timeout	451	when at least one of events specified in C<$eventmask> occurs.
104	is disabled.
105		452
106	The C<io_ns> variant doesn't add/start the newly created watcher.
107
108	Eventmask can be one or more of these constants ORed together:	453	The $eventmask can be one or more of these constants ORed together:
109		454
110	EV::READ wait until read() wouldn't block anymore	455	EV::READ wait until read() wouldn't block anymore
111	EV::WRITE wait until write() wouldn't block anymore	456	EV::WRITE wait until write() wouldn't block anymore
112	EV::PERSIST stay active after an event occured
113		457
114	=item my $w = EV::timer $after, $repeat, $callback
115
116	=item my $w = EV::timer_ns $after, $repeat, $callback
117
118	Calls the callback after C<$after> seconds. If C<$repeat> is true, the
119	timer will be restarted after the callback returns. This means that the
120	callback would be called roughly every C<$after> seconds, prolonged by the
121	time the callback takes.
122
123	The C<timer_ns> variant doesn't add/start the newly created watcher.	458	The C<io_ns> variant doesn't start (activate) the newly created watcher.
124		459
125	=item my $w = EV::timer_abs $at, $interval, $callback	460	=item $w->set ($fileno_or_fh, $eventmask)
126		461
127	=item my $w = EV::timer_abs_ns $at, $interval, $callback	462	Reconfigures the watcher, see the constructor above for details. Can be
128		463	called at any time.
129	Similar to EV::timer, but the time is given as an absolute point in time
130	(C<$at>), plus an optional C<$interval>.
131
132	If the C<$interval> is zero, then the callback will be called at the time
133	C<$at> if that is in the future, or as soon as possible if its in the
134	past. It will not automatically repeat.
135
136	If the C<$interval> is nonzero, then the watcher will always be scheduled
137	to time out at the next C<$at + integer * $interval> time.
138
139	This can be used to schedule a callback to run at very regular intervals,
140	as long as the processing time is less then the interval (otherwise
141	obviously events will be skipped).
142
143	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.
144
145	=item my $w = EV::signal $signum, $callback
146
147	=item my $w = EV::signal_ns $signum, $callback
148
149	Call the callback when signal $signum is received.
150
151	The C<signal_ns> variant doesn't add/start the newly created watcher.
152
153	=back
154
155	=head1 THE EV::Event CLASS
156
157	All EV functions creating an event watcher (designated by C<my $w =>
158	above) support the following methods on the returned watcher object:
159
160	=over 4
161
162	=item $w->add ($timeout)
163
164	Stops and (re-)starts the event watcher, setting the optional timeout to
165	the given value, or clearing the timeout if none is given.
166
167	=item $w->start
168
169	Stops and (re-)starts the event watcher without touching the timeout.
170
171	=item $w->del
172
173	=item $w->stop
174
175	Stop the event watcher if it was started.
176
177	=item $current_callback = $w->cb
178
179	=item $old_callback = $w->cb ($new_callback)
180
181	Return the previously set callback and optionally set a new one.
182		464
183	=item $current_fh = $w->fh	465	=item $current_fh = $w->fh
184		466
185	=item $old_fh = $w->fh ($new_fh)	467	=item $old_fh = $w->fh ($new_fh)
186		468
190		472
191	=item $old_eventmask = $w->events ($new_eventmask)	473	=item $old_eventmask = $w->events ($new_eventmask)
192		474
193	Returns the previously set event mask and optionally set a new one.	475	Returns the previously set event mask and optionally set a new one.
194		476
		477	=back
		478
		479
		480	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		481
		482	=over 4
		483
		484	=item $w = EV::timer $after, $repeat, $callback
		485
		486	=item $w = EV::timer_ns $after, $repeat, $callback
		487
		488	=item $w = $loop->timer ($after, $repeat, $callback)
		489
		490	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		491
		492	Calls the callback after C<$after> seconds (which may be fractional). If
		493	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		494	value as $after) after the callback returns.
		495
		496	This means that the callback would be called roughly after C<$after>
		497	seconds, and then every C<$repeat> seconds. The timer does his best not
		498	to drift, but it will not invoke the timer more often then once per event
		499	loop iteration, and might drift in other cases. If that isn't acceptable,
		500	look at EV::periodic, which can provide long-term stable timers.
		501
		502	The timer is based on a monotonic clock, that is, if somebody is sitting
		503	in front of the machine while the timer is running and changes the system
		504	clock, the timer will nevertheless run (roughly) the same time.
		505
		506	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		507
195	=item $w->timeout ($after, $repeat)	508	=item $w->set ($after, $repeat)
196		509
197	Resets the timeout (see C<EV::timer> for details).	510	Reconfigures the watcher, see the constructor above for details. Can be called at
		511	any time.
198		512
199	=item $w->timeout_abs ($at, $interval)	513	=item $w->again
200		514
201	Resets the timeout (see C<EV::timer_abs> for details).	515	Similar to the C<start> method, but has special semantics for repeating timers:
202		516
203	=item $w->priority_set ($priority)	517	If the timer is active and non-repeating, it will be stopped.
204		518
205	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	519	If the timer is active and repeating, reset the timeout to occur
		520	C<$repeat> seconds after now.
206		521
207	=back	522	If the timer is inactive and repeating, start it using the repeat value.
208		523
209	=head1 BUGS	524	Otherwise do nothing.
210		525
211	Lots. Libevent itself isn't well tested and rather buggy, and this module	526	This behaviour is useful when you have a timeout for some IO
212	is quite new at the moment.	527	operation. You create a timer object with the same value for C<$after> and
		528	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		529	on the timeout.
213		530
214	Please note that the epoll method is not, in general, reliable in	531	=back
215	programs that use fork (even if no libveent calls are being made in the	532
216	forked process). Since this is such a common issue, this module will	533
217	force the epoll method in EV to be off unless the global variable	534	=head3 PERIODIC WATCHERS - to cron or not to cron?
218	$EV::ENABLE_EPOLL is set to 1 before loading this module for the first	535
		536	=over 4
		537
		538	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		539
		540	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		541
		542	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		543
		544	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		545
		546	Similar to EV::timer, but is not based on relative timeouts but on
		547	absolute times. Apart from creating "simple" timers that trigger "at" the
		548	specified time, it can also be used for non-drifting absolute timers and
		549	more complex, cron-like, setups that are not adversely affected by time
		550	jumps (i.e. when the system clock is changed by explicit date -s or other
		551	means such as ntpd). It is also the most complex watcher type in EV.
		552
		553	It has three distinct "modes":
		554
		555	=over 4
		556
		557	=item * absolute timer ($interval = $reschedule_cb = 0)
		558
		559	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		560	will not adjust when a time jump occurs, that is, if it is to be run
		561	at January 1st 2011 then it will run when the system time reaches or
		562	surpasses this time.
		563
		564	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		565
		566	In this mode the watcher will always be scheduled to time out at the
		567	next C<$at + N * $interval> time (for some integer N) and then repeat,
		568	regardless of any time jumps.
		569
		570	This can be used to create timers that do not drift with respect to system
219	time.	571	time:
		572
		573	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		574
		575	That doesn't mean there will always be 3600 seconds in between triggers,
		576	but only that the the clalback will be called when the system time shows a
		577	full hour (UTC).
		578
		579	Another way to think about it (for the mathematically inclined) is that
		580	EV::periodic will try to run the callback in this mode at the next
		581	possible time where C<$time = $at (mod $interval)>, regardless of any time
		582	jumps.
		583
		584	=item * manual reschedule mode ($reschedule_cb = coderef)
		585
		586	In this mode $interval and $at are both being ignored. Instead, each
		587	time the periodic watcher gets scheduled, the reschedule callback
		588	($reschedule_cb) will be called with the watcher as first, and the current
		589	time as second argument.
		590
		591	I<This callback MUST NOT stop or destroy this or any other periodic
		592	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		593	you need to stop it, return 1e30 and stop it afterwards. You may create
		594	and start a C<EV::prepare> watcher for this task.
		595
		596	It must return the next time to trigger, based on the passed time value
		597	(that is, the lowest time value larger than or equal to to the second
		598	argument). It will usually be called just before the callback will be
		599	triggered, but might be called at other times, too.
		600
		601	This can be used to create very complex timers, such as a timer that
		602	triggers on each midnight, local time (actually 24 hours after the last
		603	midnight, to keep the example simple. If you know a way to do it correctly
		604	in about the same space (without requiring elaborate modules), drop me a
		605	note :):
		606
		607	my $daily = EV::periodic 0, 0, sub {
		608	my ($w, $now) = @_;
		609
		610	use Time::Local ();
		611	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		612	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		613	}, sub {
		614	print "it's midnight or likely shortly after, now\n";
		615	};
		616
		617	=back
		618
		619	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		620
		621	=item $w->set ($at, $interval, $reschedule_cb)
		622
		623	Reconfigures the watcher, see the constructor above for details. Can be called at
		624	any time.
		625
		626	=item $w->again
		627
		628	Simply stops and starts the watcher again.
		629
		630	=item $time = $w->at
		631
		632	Return the time that the watcher is expected to trigger next.
		633
		634	=back
		635
		636
		637	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		638
		639	=over 4
		640
		641	=item $w = EV::signal $signal, $callback
		642
		643	=item $w = EV::signal_ns $signal, $callback
		644
		645	Call the callback when $signal is received (the signal can be specified by
		646	number or by name, just as with C<kill> or C<%SIG>).
		647
		648	EV will grab the signal for the process (the kernel only allows one
		649	component to receive a signal at a time) when you start a signal watcher,
		650	and removes it again when you stop it. Perl does the same when you
		651	add/remove callbacks to C<%SIG>, so watch out.
		652
		653	You can have as many signal watchers per signal as you want.
		654
		655	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		656
		657	=item $w->set ($signal)
		658
		659	Reconfigures the watcher, see the constructor above for details. Can be
		660	called at any time.
		661
		662	=item $current_signum = $w->signal
		663
		664	=item $old_signum = $w->signal ($new_signal)
		665
		666	Returns the previously set signal (always as a number not name) and
		667	optionally set a new one.
		668
		669	=back
		670
		671
		672	=head3 CHILD WATCHERS - watch out for process status changes
		673
		674	=over 4
		675
		676	=item $w = EV::child $pid, $trace, $callback
		677
		678	=item $w = EV::child_ns $pid, $trace, $callback
		679
		680	=item $w = $loop->child ($pid, $trace, $callback)
		681
		682	=item $w = $loop->child_ns ($pid, $trace, $callback)
		683
		684	Call the callback when a status change for pid C<$pid> (or any pid
		685	if C<$pid> is 0) has been received (a status change happens when the
		686	process terminates or is killed, or, when trace is true, additionally when
		687	it is stopped or continued). More precisely: when the process receives
		688	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		689	changed/zombie children and call the callback.
		690
		691	It is valid (and fully supported) to install a child watcher after a child
		692	has exited but before the event loop has started its next iteration (for
		693	example, first you C<fork>, then the new child process might exit, and
		694	only then do you install a child watcher in the parent for the new pid).
		695
		696	You can access both exit (or tracing) status and pid by using the
		697	C<rstatus> and C<rpid> methods on the watcher object.
		698
		699	You can have as many pid watchers per pid as you want, they will all be
		700	called.
		701
		702	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		703
		704	=item $w->set ($pid, $trace)
		705
		706	Reconfigures the watcher, see the constructor above for details. Can be called at
		707	any time.
		708
		709	=item $current_pid = $w->pid
		710
		711	Returns the previously set process id and optionally set a new one.
		712
		713	=item $exit_status = $w->rstatus
		714
		715	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		716	in perlfunc).
		717
		718	=item $pid = $w->rpid
		719
		720	Return the pid of the awaited child (useful when you have installed a
		721	watcher for all pids).
		722
		723	=back
		724
		725
		726	=head3 STAT WATCHERS - did the file attributes just change?
		727
		728	=over 4
		729
		730	=item $w = EV::stat $path, $interval, $callback
		731
		732	=item $w = EV::stat_ns $path, $interval, $callback
		733
		734	=item $w = $loop->stat ($path, $interval, $callback)
		735
		736	=item $w = $loop->stat_ns ($path, $interval, $callback)
		737
		738	Call the callback when a file status change has been detected on
		739	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		740	to "path does not exist" is a status change like any other.
		741
		742	The C<$interval> is a recommended polling interval for systems where
		743	OS-supported change notifications don't exist or are not supported. If
		744	you use C<0> then an unspecified default is used (which is highly
		745	recommended!), which is to be expected to be around five seconds usually.
		746
		747	This watcher type is not meant for massive numbers of stat watchers,
		748	as even with OS-supported change notifications, this can be
		749	resource-intensive.
		750
		751	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		752
		753	=item ... = $w->stat
		754
		755	This call is very similar to the perl C<stat> built-in: It stats (using
		756	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		757	well as EV's idea of the current stat values) to the values found.
		758
		759	In scalar context, a boolean is return indicating success or failure of
		760	the stat. In list context, the same 13-value list as with stat is returned
		761	(except that the blksize and blocks fields are not reliable).
		762
		763	In the case of an error, errno is set to C<ENOENT> (regardless of the
		764	actual error value) and the C<nlink> value is forced to zero (if the stat
		765	was successful then nlink is guaranteed to be non-zero).
		766
		767	See also the next two entries for more info.
		768
		769	=item ... = $w->attr
		770
		771	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		772	the values most recently detected by EV. See the next entry for more info.
		773
		774	=item ... = $w->prev
		775
		776	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		777	the previous set of values, before the change.
		778
		779	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		780	to the values found I<before> a change was detected, while C<< $w->attr >>
		781	returns the values found leading to the change detection. The difference (if any)
		782	between C<prev> and C<attr> is what triggered the callback.
		783
		784	If you did something to the filesystem object and do not want to trigger
		785	yet another change, you can call C<stat> to update EV's idea of what the
		786	current attributes are.
		787
		788	=item $w->set ($path, $interval)
		789
		790	Reconfigures the watcher, see the constructor above for details. Can be
		791	called at any time.
		792
		793	=item $current_path = $w->path
		794
		795	=item $old_path = $w->path ($new_path)
		796
		797	Returns the previously set path and optionally set a new one.
		798
		799	=item $current_interval = $w->interval
		800
		801	=item $old_interval = $w->interval ($new_interval)
		802
		803	Returns the previously set interval and optionally set a new one. Can be
		804	used to query the actual interval used.
		805
		806	=back
		807
		808
		809	=head3 IDLE WATCHERS - when you've got nothing better to do...
		810
		811	=over 4
		812
		813	=item $w = EV::idle $callback
		814
		815	=item $w = EV::idle_ns $callback
		816
		817	=item $w = $loop->idle ($callback)
		818
		819	=item $w = $loop->idle_ns ($callback)
		820
		821	Call the callback when there are no other pending watchers of the same or
		822	higher priority (excluding check, prepare and other idle watchers of the
		823	same or lower priority, of course). They are called idle watchers because
		824	when the watcher is the highest priority pending event in the process, the
		825	process is considered to be idle at that priority.
		826
		827	If you want a watcher that is only ever called when I<no> other events are
		828	outstanding you have to set the priority to C<EV::MINPRI>.
		829
		830	The process will not block as long as any idle watchers are active, and
		831	they will be called repeatedly until stopped.
		832
		833	For example, if you have idle watchers at priority C<0> and C<1>, and
		834	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		835	and the I/O watcher will always run when ready. Only when the idle watcher
		836	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		837	pending with the C<0>-priority idle watcher be invoked.
		838
		839	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		840
		841	=back
		842
		843
		844	=head3 PREPARE WATCHERS - customise your event loop!
		845
		846	=over 4
		847
		848	=item $w = EV::prepare $callback
		849
		850	=item $w = EV::prepare_ns $callback
		851
		852	=item $w = $loop->prepare ($callback)
		853
		854	=item $w = $loop->prepare_ns ($callback)
		855
		856	Call the callback just before the process would block. You can still
		857	create/modify any watchers at this point.
		858
		859	See the EV::check watcher, below, for explanations and an example.
		860
		861	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		862
		863	=back
		864
		865
		866	=head3 CHECK WATCHERS - customise your event loop even more!
		867
		868	=over 4
		869
		870	=item $w = EV::check $callback
		871
		872	=item $w = EV::check_ns $callback
		873
		874	=item $w = $loop->check ($callback)
		875
		876	=item $w = $loop->check_ns ($callback)
		877
		878	Call the callback just after the process wakes up again (after it has
		879	gathered events), but before any other callbacks have been invoked.
		880
		881	This is used to integrate other event-based software into the EV
		882	mainloop: You register a prepare callback and in there, you create io and
		883	timer watchers as required by the other software. Here is a real-world
		884	example of integrating Net::SNMP (with some details left out):
		885
		886	our @snmp_watcher;
		887
		888	our $snmp_prepare = EV::prepare sub {
		889	# do nothing unless active
		890	$dispatcher->{_event_queue_h}
		891	or return;
		892
		893	# make the dispatcher handle any outstanding stuff
		894	... not shown
		895
		896	# create an I/O watcher for each and every socket
		897	@snmp_watcher = (
		898	(map { EV::io $_, EV::READ, sub { } }
		899	keys %{ $dispatcher->{_descriptors} }),
		900
		901	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		902	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		903	0, sub { },
		904	);
		905	};
		906
		907	The callbacks are irrelevant (and are not even being called), the
		908	only purpose of those watchers is to wake up the process as soon as
		909	one of those events occurs (socket readable, or timer timed out). The
		910	corresponding EV::check watcher will then clean up:
		911
		912	our $snmp_check = EV::check sub {
		913	# destroy all watchers
		914	@snmp_watcher = ();
		915
		916	# make the dispatcher handle any new stuff
		917	... not shown
		918	};
		919
		920	The callbacks of the created watchers will not be called as the watchers
		921	are destroyed before this cna happen (remember EV::check gets called
		922	first).
		923
		924	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		925
		926	=back
		927
		928
		929	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		930
		931	Fork watchers are called when a C<fork ()> was detected. The invocation
		932	is done before the event loop blocks next and before C<check> watchers
		933	are being called, and only in the child after the fork.
		934
		935	=over 4
		936
		937	=item $w = EV::fork $callback
		938
		939	=item $w = EV::fork_ns $callback
		940
		941	=item $w = $loop->fork ($callback)
		942
		943	=item $w = $loop->fork_ns ($callback)
		944
		945	Call the callback before the event loop is resumed in the child process
		946	after a fork.
		947
		948	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		949
		950	=back
		951
		952
		953	=head3 EMBED WATCHERS - when one backend isn't enough...
		954
		955	This is a rather advanced watcher type that lets you embed one event loop
		956	into another (currently only IO events are supported in the embedded
		957	loop, other types of watchers might be handled in a delayed or incorrect
		958	fashion and must not be used).
		959
		960	See the libev documentation at
		961	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		962	for more details.
		963
		964	In short, this watcher is most useful on BSD systems without working
		965	kqueue to still be able to handle a large number of sockets:
		966
		967	my $socket_loop;
		968
		969	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		970	if (
		971	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		972	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		973	) {
		974	# use kqueue for sockets
		975	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		976	}
		977
		978	# use the default loop otherwise
		979	$socket_loop \|\|= EV::default_loop;
		980
		981	=over 4
		982
		983	=item $w = EV::embed $otherloop[, $callback]
		984
		985	=item $w = EV::embed_ns $otherloop[, $callback]
		986
		987	=item $w = $loop->embed ($otherloop[, $callback])
		988
		989	=item $w = $loop->embed_ns ($otherloop[, $callback])
		990
		991	Call the callback when the embedded event loop (C<$otherloop>) has any
		992	I/O activity. The C<$callback> is optional: if it is missing, then the
		993	embedded event loop will be managed automatically (which is recommended),
		994	otherwise you have to invoke C<sweep> yourself.
		995
		996	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		997
		998	=back
		999
		1000	=head3 ASYNC WATCHERS - how to wake up another event loop
		1001
		1002	Async watchers are provided by EV, but have little use in perl directly, as perl
		1003	neither supports threads nor direct access to signal handlers or other
		1004	contexts where they could be of value.
		1005
		1006	It is, however, possible to use them from the XS level.
		1007
		1008	Please see the libev documentation for further details.
		1009
		1010	=over 4
		1011
		1012	=item $w = EV::async $callback
		1013
		1014	=item $w = EV::async_ns $callback
		1015
		1016	=item $w->send
		1017
		1018	=item $bool = $w->async_pending
		1019
		1020	=back
		1021
		1022
		1023	=head1 PERL SIGNALS
		1024
		1025	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1026	with EV is as the same as any other C library: Perl-signals will only be
		1027	handled when Perl runs, which means your signal handler might be invoked
		1028	only the next time an event callback is invoked.
		1029
		1030	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1031	ensure proper operations with regards to other event watchers.
		1032
		1033	If you cannot do this for whatever reason, you can also force a watcher
		1034	to be called on every event loop iteration by installing a C<EV::check>
		1035	watcher:
		1036
		1037	my $async_check = EV::check sub { };
		1038
		1039	This ensures that perl gets into control for a short time to handle any
		1040	pending signals, and also ensures (slightly) slower overall operation.
		1041
		1042	=head1 THREADS
		1043
		1044	Threads are not supported by this module in any way. Perl pseudo-threads
		1045	is evil stuff and must die. As soon as Perl gains real threads I will work
		1046	on thread support for it.
		1047
		1048	=head1 FORK
		1049
		1050	Most of the "improved" event delivering mechanisms of modern operating
		1051	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1052	not supported and usually destructive). Libev makes it possible to work
		1053	around this by having a function that recreates the kernel state after
		1054	fork in the child.
		1055
		1056	On non-win32 platforms, this module requires the pthread_atfork
		1057	functionality to do this automatically for you. This function is quite
		1058	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1059	negligible, because everything the function currently does is set a flag
		1060	that is checked only when the event loop gets used the next time, so when
		1061	you do fork but not use EV, the overhead is minimal.
		1062
		1063	On win32, there is no notion of fork so all this doesn't apply, of course.
220		1064
221	=cut	1065	=cut
222		1066
223	our $NPRI = 4;	1067	our $DIED = sub {
224	our $BASE;	1068	warn "EV: error in callback (ignoring): $@";
225	our $ENABLE_EPOLL;	1069	};
226		1070
227	{	1071	default_loop
228	local $ENV{EVENT_NOEPOLL};	1072	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
229	$ENV{EVENT_NOEPOLL} = 1 unless $ENABLE_EPOLL;
230	$BASE = init;
231	}
232
233	priority_init $NPRI;
234
235	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
236		1073
237	1;	1074	1;
238		1075
239	=head1 SEE ALSO	1076	=head1 SEE ALSO
240		1077
241	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1078	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
242	L<EV::AnyEvent>.	1079	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1080	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1081	event-loop agnostic and portable event driven programming.
243		1082
244	=head1 AUTHOR	1083	=head1 AUTHOR
245		1084
246	Marc Lehmann <schmorp@schmorp.de>	1085	Marc Lehmann <schmorp@schmorp.de>
247	http://home.schmorp.de/	1086	http://home.schmorp.de/
248		1087
249	=cut	1088	=cut
250		1089

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Comparing EV/EV.pm (file contents): Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs. Revision 1.103 by root, Thu Oct 2 07:49:09 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs.
Revision 1.103 by root, Thu Oct 2 07:49:09 2008 UTC