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

Comparing EV/EV.pm (file contents):
Revision 1.2 by root, Fri Oct 26 17:24:17 2007 UTC vs.
Revision 1.116 by root, Sat Jun 13 15:11:54 2009 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/>).	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		60	below is comprehensive, one might also consult the documentation of
		61	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		62	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		63	discussion on the available backends, or how to force a specific backend
		64	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		65	detailed information.
		66
		67	This module is very fast and scalable. It is actually so fast that you
		68	can use it through the L<AnyEvent> module, stay portable to other event
		69	loops (if you don't rely on any watcher types not available through it)
		70	and still be faster than with any other event loop currently supported in
		71	Perl.
		72
		73	=head2 MODULE EXPORTS
		74
		75	This module does not export any symbols.
47		76
48	=cut	77	=cut
49		78
50	package EV;	79	package EV;
51		80
		81	no warnings;
52	use strict;	82	use strict;
53		83
54	BEGIN {	84	BEGIN {
55	our $VERSION = '0.01';	85	our $VERSION = '3.6';
56	use XSLoader;	86	use XSLoader;
57	XSLoader::load "EV", $VERSION;	87	XSLoader::load "EV", $VERSION;
58	}	88	}
59		89
60	=head1 FUNCTIONAL INTERFACE	90	@EV::IO::ISA =
		91	@EV::Timer::ISA =
		92	@EV::Periodic::ISA =
		93	@EV::Signal::ISA =
		94	@EV::Child::ISA =
		95	@EV::Stat::ISA =
		96	@EV::Idle::ISA =
		97	@EV::Prepare::ISA =
		98	@EV::Check::ISA =
		99	@EV::Embed::ISA =
		100	@EV::Fork::ISA =
		101	@EV::Async::ISA =
		102	"EV::Watcher";
61		103
62	=over 4	104	@EV::Loop::Default::ISA = "EV::Loop";
63		105
		106	=head1 EVENT LOOPS
		107
		108	EV supports multiple event loops: There is a single "default event loop"
		109	that can handle everything including signals and child watchers, and any
		110	number of "dynamic event loops" that can use different backends (with
		111	various limitations), but no child and signal watchers.
		112
		113	You do not have to do anything to create the default event loop: When
		114	the module is loaded a suitable backend is selected on the premise of
		115	selecting a working backend (which for example rules out kqueue on most
		116	BSDs). Modules should, unless they have "special needs" always use the
		117	default loop as this is fastest (perl-wise), best supported by other
		118	modules (e.g. AnyEvent or Coro) and most portable event loop.
		119
		120	For specific programs you can create additional event loops dynamically.
		121
		122	If you want to take advantage of kqueue (which often works properly for
		123	sockets only) even though the default loop doesn't enable it, you can
		124	I<embed> a kqueue loop into the default loop: running the default loop
		125	will then also service the kqueue loop to some extent. See the example in
		126	the section about embed watchers for an example on how to achieve that.
		127
		128	=over 4
		129
		130	=item $loop = new EV::Loop [$flags]
		131
		132	Create a new event loop as per the specified flags. Please refer to
		133	the C<ev_loop_new ()> function description in the libev documentation
		134	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		135	or locally-installed as F<EV::libev> manpage) for more info.
		136
		137	The loop will automatically be destroyed when it is no longer referenced
		138	by any watcher and the loop object goes out of scope.
		139
		140	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		141	is recommended, as only the default event loop is protected by this
		142	module. If you I<are> embedding this loop in the default loop, this is not
		143	necessary, as C<EV::embed> automatically does the right thing on fork.
		144
		145	=item $loop->loop_fork
		146
		147	Must be called after a fork in the child, before entering or continuing
		148	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		149	this function automatically, at some performance loss (refer to the libev
		150	documentation).
		151
		152	=item $loop->loop_verify
		153
		154	Calls C<ev_verify> to make internal consistency checks (for debugging
		155	libev) and abort the program if any data structures were found to be
		156	corrupted.
		157
		158	=item $loop = EV::default_loop [$flags]
		159
		160	Return the default loop (which is a singleton object). Since this module
		161	already creates the default loop with default flags, specifying flags here
		162	will not have any effect unless you destroy the default loop first, which
		163	isn't supported. So in short: don't do it, and if you break it, you get to
		164	keep the pieces.
		165
		166	=back
		167
		168
		169	=head1 BASIC INTERFACE
		170
		171	=over 4
		172
64	=item $EV::NPRI	173	=item $EV::DIED
65		174
66	How many priority levels are available.	175	Must contain a reference to a function that is called when a callback
		176	throws an exception (with $@ containing the error). The default prints an
		177	informative message and continues.
		178
		179	If this callback throws an exception it will be silently ignored.
		180
		181	=item $flags = EV::supported_backends
		182
		183	=item $flags = EV::recommended_backends
		184
		185	=item $flags = EV::embeddable_backends
		186
		187	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		188	instance of EV, the set of recommended backends (supposed to be good) for
		189	this platform and the set of embeddable backends (see EMBED WATCHERS).
		190
		191	=item EV::sleep $seconds
		192
		193	Block the process for the given number of (fractional) seconds.
		194
		195	=item $time = EV::time
		196
		197	Returns the current time in (fractional) seconds since the epoch.
67		198
68	=item $time = EV::now	199	=item $time = EV::now
69		200
70	Returns the time in (fractional) seconds since the epoch.	201	=item $time = $loop->now
71		202
72	=item $version = EV::version	203	Returns the time the last event loop iteration has been started. This
		204	is the time that (relative) timers are based on, and referring to it is
		205	usually faster then calling EV::time.
73		206
74	=item $method = EV::method	207	=item EV::now_update
75		208
76	Return version string and event polling method used.	209	=item $loop->now_update
77		210
78	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	211	Establishes the current time by querying the kernel, updating the time
		212	returned by C<EV::now> in the progress. This is a costly operation and
		213	is usually done automatically within C<EV::loop>.
79		214
80	=item EV::loopexit $after	215	This function is rarely useful, but when some event callback runs for a
		216	very long time without entering the event loop, updating libev's idea of
		217	the current time is a good idea.
81		218
82	Exit any active loop or dispatch after C<$after> seconds or immediately if	219	=item EV::suspend
83	C<$after> is missing or zero.
84		220
85	=item EV::dispatch	221	=item $loop->suspend
86		222
87	Same as C<EV::loop 0>.	223	=item EV::resume
88		224
89	=item EV::event $callback	225	=item $loop->resume
90		226
91	Creates a new event watcher waiting for nothing, calling the given callback.	227	These two functions suspend and resume a loop, for use when the loop is
		228	not used for a while and timeouts should not be processed.
92		229
		230	A typical use case would be an interactive program such as a game: When
		231	the user presses C<^Z> to suspend the game and resumes it an hour later it
		232	would be best to handle timeouts as if no time had actually passed while
		233	the program was suspended. This can be achieved by calling C<suspend>
		234	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		235	C<resume> directly afterwards to resume timer processing.
		236
		237	Effectively, all C<timer> watchers will be delayed by the time spend
		238	between C<suspend> and C<resume>, and all C<periodic> watchers
		239	will be rescheduled (that is, they will lose any events that would have
		240	occured while suspended).
		241
		242	After calling C<suspend> you B<must not> call I<any> function on the given
		243	loop other than C<resume>, and you B<must not> call C<resume>
		244	without a previous call to C<suspend>.
		245
		246	Calling C<suspend>/C<resume> has the side effect of updating the event
		247	loop time (see C<now_update>).
		248
		249	=item $backend = EV::backend
		250
		251	=item $backend = $loop->backend
		252
		253	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
		254	or EV::BACKEND_EPOLL).
		255
		256	=item EV::loop [$flags]
		257
		258	=item $loop->loop ([$flags])
		259
		260	Begin checking for events and calling callbacks. It returns when a
		261	callback calls EV::unloop.
		262
		263	The $flags argument can be one of the following:
		264
		265	0 as above
		266	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		267	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
		268
		269	=item EV::unloop [$how]
		270
		271	=item $loop->unloop ([$how])
		272
		273	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		274	innermost call to EV::loop return.
		275
		276	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		277	fast as possible.
		278
		279	=item $count = EV::loop_count
		280
		281	=item $count = $loop->loop_count
		282
		283	Return the number of times the event loop has polled for new
		284	events. Sometimes useful as a generation counter.
		285
		286	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		287
		288	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		289
		290	This function rolls together an I/O and a timer watcher for a single
		291	one-shot event without the need for managing a watcher object.
		292
		293	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		294	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		295	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		296	you do not want to wait for some I/O event, specify C<undef> for
		297	C<$fh_or_undef> and C<0> for C<$events>).
		298
		299	If timeout is C<undef> or negative, then there will be no
		300	timeout. Otherwise a EV::timer with this value will be started.
		301
		302	When an error occurs or either the timeout or I/O watcher triggers, then
		303	the callback will be called with the received event set (in general
		304	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		305	C<EV::WRITE> and C<EV::TIMEOUT>).
		306
		307	EV::once doesn't return anything: the watchers stay active till either
		308	of them triggers, then they will be stopped and freed, and the callback
		309	invoked.
		310
		311	=item EV::feed_fd_event ($fd, $revents)
		312
		313	=item $loop->feed_fd_event ($fd, $revents)
		314
		315	Feed an event on a file descriptor into EV. EV will react to this call as
		316	if the readyness notifications specified by C<$revents> (a combination of
		317	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		318
		319	=item EV::feed_signal_event ($signal)
		320
		321	Feed a signal event into EV. EV will react to this call as if the signal
		322	specified by C<$signal> had occured.
		323
		324	=item EV::set_io_collect_interval $time
		325
		326	=item $loop->set_io_collect_interval ($time)
		327
		328	=item EV::set_timeout_collect_interval $time
		329
		330	=item $loop->set_timeout_collect_interval ($time)
		331
		332	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		333	wait interval for timer events. See the libev documentation at
		334	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		335	(locally installed as F<EV::libev>) for a more detailed discussion.
		336
		337	=back
		338
		339
		340	=head1 WATCHER OBJECTS
		341
		342	A watcher is an object that gets created to record your interest in some
		343	event. For instance, if you want to wait for STDIN to become readable, you
		344	would create an EV::io watcher for that:
		345
		346	my $watcher = EV::io *STDIN, EV::READ, sub {
		347	my ($watcher, $revents) = @_;
		348	warn "yeah, STDIN should now be readable without blocking!\n"
		349	};
		350
		351	All watchers can be active (waiting for events) or inactive (paused). Only
		352	active watchers will have their callbacks invoked. All callbacks will be
		353	called with at least two arguments: the watcher and a bitmask of received
		354	events.
		355
		356	Each watcher type has its associated bit in revents, so you can use the
		357	same callback for multiple watchers. The event mask is named after the
		358	type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		359	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		360	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		361	uses EV::TIMEOUT).
		362
		363	In the rare case where one wants to create a watcher but not start it at
		364	the same time, each constructor has a variant with a trailing C<_ns> in
		365	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		366
		367	Please note that a watcher will automatically be stopped when the watcher
		368	object is destroyed, so you I<need> to keep the watcher objects returned by
		369	the constructors.
		370
		371	Also, all methods changing some aspect of a watcher (->set, ->priority,
		372	->fh and so on) automatically stop and start it again if it is active,
		373	which means pending events get lost.
		374
		375	=head2 COMMON WATCHER METHODS
		376
		377	This section lists methods common to all watchers.
		378
		379	=over 4
		380
		381	=item $w->start
		382
		383	Starts a watcher if it isn't active already. Does nothing to an already
		384	active watcher. By default, all watchers start out in the active state
		385	(see the description of the C<_ns> variants if you need stopped watchers).
		386
		387	=item $w->stop
		388
		389	Stop a watcher if it is active. Also clear any pending events (events that
		390	have been received but that didn't yet result in a callback invocation),
		391	regardless of whether the watcher was active or not.
		392
		393	=item $bool = $w->is_active
		394
		395	Returns true if the watcher is active, false otherwise.
		396
		397	=item $current_data = $w->data
		398
		399	=item $old_data = $w->data ($new_data)
		400
		401	Queries a freely usable data scalar on the watcher and optionally changes
		402	it. This is a way to associate custom data with a watcher:
		403
		404	my $w = EV::timer 60, 0, sub {
		405	warn $_[0]->data;
		406	};
		407	$w->data ("print me!");
		408
		409	=item $current_cb = $w->cb
		410
		411	=item $old_cb = $w->cb ($new_cb)
		412
		413	Queries the callback on the watcher and optionally changes it. You can do
		414	this at any time without the watcher restarting.
		415
		416	=item $current_priority = $w->priority
		417
		418	=item $old_priority = $w->priority ($new_priority)
		419
		420	Queries the priority on the watcher and optionally changes it. Pending
		421	watchers with higher priority will be invoked first. The valid range of
		422	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		423	-2). If the priority is outside this range it will automatically be
		424	normalised to the nearest valid priority.
		425
		426	The default priority of any newly-created watcher is 0.
		427
		428	Note that the priority semantics have not yet been fleshed out and are
		429	subject to almost certain change.
		430
		431	=item $w->invoke ($revents)
		432
		433	Call the callback now with the given event mask.
		434
		435	=item $w->feed_event ($revents)
		436
		437	Feed some events on this watcher into EV. EV will react to this call as if
		438	the watcher had received the given C<$revents> mask.
		439
		440	=item $revents = $w->clear_pending
		441
		442	If the watcher is pending, this function clears its pending status and
		443	returns its C<$revents> bitset (as if its callback was invoked). If the
		444	watcher isn't pending it does nothing and returns C<0>.
		445
		446	=item $previous_state = $w->keepalive ($bool)
		447
		448	Normally, C<EV::loop> will return when there are no active watchers
		449	(which is a "deadlock" because no progress can be made anymore). This is
		450	convinient because it allows you to start your watchers (and your jobs),
		451	call C<EV::loop> once and when it returns you know that all your jobs are
		452	finished (or they forgot to register some watchers for their task :).
		453
		454	Sometimes, however, this gets in your way, for example when the module
		455	that calls C<EV::loop> (usually the main program) is not the same module
		456	as a long-living watcher (for example a DNS client module written by
		457	somebody else even). Then you might want any outstanding requests to be
		458	handled, but you would not want to keep C<EV::loop> from returning just
		459	because you happen to have this long-running UDP port watcher.
		460
		461	In this case you can clear the keepalive status, which means that even
		462	though your watcher is active, it won't keep C<EV::loop> from returning.
		463
		464	The initial value for keepalive is true (enabled), and you can change it
		465	any time.
		466
		467	Example: Register an I/O watcher for some UDP socket but do not keep the
		468	event loop from running just because of that watcher.
		469
		470	my $udp_socket = ...
		471	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		472	$udp_watcher->keepalive (0);
		473
		474	=item $loop = $w->loop
		475
		476	Return the loop that this watcher is attached to.
		477
		478	=back
		479
		480
		481	=head1 WATCHER TYPES
		482
		483	Each of the following subsections describes a single watcher type.
		484
		485	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		486
		487	=over 4
		488
93	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	489	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
94		490
95	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	491	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		492
		493	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		494
		495	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
96		496
97	As long as the returned watcher object is alive, call the C<$callback>	497	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	498	when at least one of events specified in C<$eventmask> occurs.
99	is disabled.
100		499
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:	500	The $eventmask can be one or more of these constants ORed together:
104		501
105	EV::READ wait until read() wouldn't block anymore	502	EV::READ wait until read() wouldn't block anymore
106	EV::WRITE wait until write() wouldn't block anymore	503	EV::WRITE wait until write() wouldn't block anymore
107	EV::PERSIST stay active after an event occured
108		504
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.	505	The C<io_ns> variant doesn't start (activate) the newly created watcher.
119		506
120	=item my $w = EV::timer_abs $at, $interval, $callback	507	=item $w->set ($fileno_or_fh, $eventmask)
121		508
122	=item my $w = EV::timer_abs_ns $at, $interval, $callback	509	Reconfigures the watcher, see the constructor above for details. Can be
123		510	called at any time.
124	Similar to EV::timer, but the time is given as an absolute point in time
125	(C<$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		511
178	=item $current_fh = $w->fh	512	=item $current_fh = $w->fh
179		513
180	=item $old_fh = $w->fh ($new_fh)	514	=item $old_fh = $w->fh ($new_fh)
181		515
185		519
186	=item $old_eventmask = $w->events ($new_eventmask)	520	=item $old_eventmask = $w->events ($new_eventmask)
187		521
188	Returns the previously set event mask and optionally set a new one.	522	Returns the previously set event mask and optionally set a new one.
189		523
		524	=back
		525
		526
		527	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		528
		529	=over 4
		530
		531	=item $w = EV::timer $after, $repeat, $callback
		532
		533	=item $w = EV::timer_ns $after, $repeat, $callback
		534
		535	=item $w = $loop->timer ($after, $repeat, $callback)
		536
		537	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		538
		539	Calls the callback after C<$after> seconds (which may be fractional). If
		540	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		541	value as $after) after the callback returns.
		542
		543	This means that the callback would be called roughly after C<$after>
		544	seconds, and then every C<$repeat> seconds. The timer does his best not
		545	to drift, but it will not invoke the timer more often then once per event
		546	loop iteration, and might drift in other cases. If that isn't acceptable,
		547	look at EV::periodic, which can provide long-term stable timers.
		548
		549	The timer is based on a monotonic clock, that is, if somebody is sitting
		550	in front of the machine while the timer is running and changes the system
		551	clock, the timer will nevertheless run (roughly) the same time.
		552
		553	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		554
190	=item $w->timeout ($after, $repeat)	555	=item $w->set ($after, $repeat)
191		556
192	Resets the timeout (see C<EV::timer> for details).	557	Reconfigures the watcher, see the constructor above for details. Can be called at
		558	any time.
193		559
		560	=item $w->again
		561
		562	Similar to the C<start> method, but has special semantics for repeating timers:
		563
		564	If the timer is active and non-repeating, it will be stopped.
		565
		566	If the timer is active and repeating, reset the timeout to occur
		567	C<$repeat> seconds after now.
		568
		569	If the timer is inactive and repeating, start it using the repeat value.
		570
		571	Otherwise do nothing.
		572
		573	This behaviour is useful when you have a timeout for some IO
		574	operation. You create a timer object with the same value for C<$after> and
		575	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		576	on the timeout.
		577
		578	=back
		579
		580
		581	=head3 PERIODIC WATCHERS - to cron or not to cron?
		582
		583	=over 4
		584
		585	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		586
		587	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		588
		589	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		590
		591	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		592
		593	Similar to EV::timer, but is not based on relative timeouts but on
		594	absolute times. Apart from creating "simple" timers that trigger "at" the
		595	specified time, it can also be used for non-drifting absolute timers and
		596	more complex, cron-like, setups that are not adversely affected by time
		597	jumps (i.e. when the system clock is changed by explicit date -s or other
		598	means such as ntpd). It is also the most complex watcher type in EV.
		599
		600	It has three distinct "modes":
		601
		602	=over 4
		603
		604	=item * absolute timer ($interval = $reschedule_cb = 0)
		605
		606	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		607	will not adjust when a time jump occurs, that is, if it is to be run
		608	at January 1st 2011 then it will run when the system time reaches or
		609	surpasses this time.
		610
		611	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		612
		613	In this mode the watcher will always be scheduled to time out at the
		614	next C<$at + N * $interval> time (for some integer N) and then repeat,
		615	regardless of any time jumps.
		616
		617	This can be used to create timers that do not drift with respect to system
		618	time:
		619
		620	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		621
		622	That doesn't mean there will always be 3600 seconds in between triggers,
		623	but only that the the clalback will be called when the system time shows a
		624	full hour (UTC).
		625
		626	Another way to think about it (for the mathematically inclined) is that
		627	EV::periodic will try to run the callback in this mode at the next
		628	possible time where C<$time = $at (mod $interval)>, regardless of any time
		629	jumps.
		630
		631	=item * manual reschedule mode ($reschedule_cb = coderef)
		632
		633	In this mode $interval and $at are both being ignored. Instead, each
		634	time the periodic watcher gets scheduled, the reschedule callback
		635	($reschedule_cb) will be called with the watcher as first, and the current
		636	time as second argument.
		637
		638	I<This callback MUST NOT stop or destroy this or any other periodic
		639	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		640	you need to stop it, return 1e30 and stop it afterwards. You may create
		641	and start a C<EV::prepare> watcher for this task.
		642
		643	It must return the next time to trigger, based on the passed time value
		644	(that is, the lowest time value larger than or equal to to the second
		645	argument). It will usually be called just before the callback will be
		646	triggered, but might be called at other times, too.
		647
		648	This can be used to create very complex timers, such as a timer that
		649	triggers on each midnight, local time (actually 24 hours after the last
		650	midnight, to keep the example simple. If you know a way to do it correctly
		651	in about the same space (without requiring elaborate modules), drop me a
		652	note :):
		653
		654	my $daily = EV::periodic 0, 0, sub {
		655	my ($w, $now) = @_;
		656
		657	use Time::Local ();
		658	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		659	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		660	}, sub {
		661	print "it's midnight or likely shortly after, now\n";
		662	};
		663
		664	=back
		665
		666	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		667
		668	=item $w->set ($at, $interval, $reschedule_cb)
		669
		670	Reconfigures the watcher, see the constructor above for details. Can be called at
		671	any time.
		672
		673	=item $w->again
		674
		675	Simply stops and starts the watcher again.
		676
		677	=item $time = $w->at
		678
		679	Return the time that the watcher is expected to trigger next.
		680
		681	=back
		682
		683
		684	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		685
		686	=over 4
		687
		688	=item $w = EV::signal $signal, $callback
		689
		690	=item $w = EV::signal_ns $signal, $callback
		691
		692	Call the callback when $signal is received (the signal can be specified by
		693	number or by name, just as with C<kill> or C<%SIG>).
		694
		695	EV will grab the signal for the process (the kernel only allows one
		696	component to receive a signal at a time) when you start a signal watcher,
		697	and removes it again when you stop it. Perl does the same when you
		698	add/remove callbacks to C<%SIG>, so watch out.
		699
		700	You can have as many signal watchers per signal as you want.
		701
		702	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		703
		704	=item $w->set ($signal)
		705
		706	Reconfigures the watcher, see the constructor above for details. Can be
		707	called at any time.
		708
		709	=item $current_signum = $w->signal
		710
		711	=item $old_signum = $w->signal ($new_signal)
		712
		713	Returns the previously set signal (always as a number not name) and
		714	optionally set a new one.
		715
		716	=back
		717
		718
		719	=head3 CHILD WATCHERS - watch out for process status changes
		720
		721	=over 4
		722
		723	=item $w = EV::child $pid, $trace, $callback
		724
		725	=item $w = EV::child_ns $pid, $trace, $callback
		726
		727	=item $w = $loop->child ($pid, $trace, $callback)
		728
		729	=item $w = $loop->child_ns ($pid, $trace, $callback)
		730
		731	Call the callback when a status change for pid C<$pid> (or any pid
		732	if C<$pid> is 0) has been received (a status change happens when the
		733	process terminates or is killed, or, when trace is true, additionally when
		734	it is stopped or continued). More precisely: when the process receives
		735	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		736	changed/zombie children and call the callback.
		737
		738	It is valid (and fully supported) to install a child watcher after a child
		739	has exited but before the event loop has started its next iteration (for
		740	example, first you C<fork>, then the new child process might exit, and
		741	only then do you install a child watcher in the parent for the new pid).
		742
		743	You can access both exit (or tracing) status and pid by using the
		744	C<rstatus> and C<rpid> methods on the watcher object.
		745
		746	You can have as many pid watchers per pid as you want, they will all be
		747	called.
		748
		749	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		750
		751	=item $w->set ($pid, $trace)
		752
		753	Reconfigures the watcher, see the constructor above for details. Can be called at
		754	any time.
		755
		756	=item $current_pid = $w->pid
		757
		758	Returns the previously set process id and optionally set a new one.
		759
		760	=item $exit_status = $w->rstatus
		761
		762	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		763	in perlfunc).
		764
		765	=item $pid = $w->rpid
		766
		767	Return the pid of the awaited child (useful when you have installed a
		768	watcher for all pids).
		769
		770	=back
		771
		772
		773	=head3 STAT WATCHERS - did the file attributes just change?
		774
		775	=over 4
		776
		777	=item $w = EV::stat $path, $interval, $callback
		778
		779	=item $w = EV::stat_ns $path, $interval, $callback
		780
		781	=item $w = $loop->stat ($path, $interval, $callback)
		782
		783	=item $w = $loop->stat_ns ($path, $interval, $callback)
		784
		785	Call the callback when a file status change has been detected on
		786	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		787	to "path does not exist" is a status change like any other.
		788
		789	The C<$interval> is a recommended polling interval for systems where
		790	OS-supported change notifications don't exist or are not supported. If
		791	you use C<0> then an unspecified default is used (which is highly
		792	recommended!), which is to be expected to be around five seconds usually.
		793
		794	This watcher type is not meant for massive numbers of stat watchers,
		795	as even with OS-supported change notifications, this can be
		796	resource-intensive.
		797
		798	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		799
		800	=item ... = $w->stat
		801
		802	This call is very similar to the perl C<stat> built-in: It stats (using
		803	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		804	well as EV's idea of the current stat values) to the values found.
		805
		806	In scalar context, a boolean is return indicating success or failure of
		807	the stat. In list context, the same 13-value list as with stat is returned
		808	(except that the blksize and blocks fields are not reliable).
		809
		810	In the case of an error, errno is set to C<ENOENT> (regardless of the
		811	actual error value) and the C<nlink> value is forced to zero (if the stat
		812	was successful then nlink is guaranteed to be non-zero).
		813
		814	See also the next two entries for more info.
		815
		816	=item ... = $w->attr
		817
		818	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		819	the values most recently detected by EV. See the next entry for more info.
		820
		821	=item ... = $w->prev
		822
		823	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		824	the previous set of values, before the change.
		825
		826	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		827	to the values found I<before> a change was detected, while C<< $w->attr >>
		828	returns the values found leading to the change detection. The difference (if any)
		829	between C<prev> and C<attr> is what triggered the callback.
		830
		831	If you did something to the filesystem object and do not want to trigger
		832	yet another change, you can call C<stat> to update EV's idea of what the
		833	current attributes are.
		834
194	=item $w->timeout_abs ($at, $interval)	835	=item $w->set ($path, $interval)
195		836
196	Resets the timeout (see C<EV::timer_abs> for details).	837	Reconfigures the watcher, see the constructor above for details. Can be
		838	called at any time.
197		839
198	=item $w->priority_set ($priority)	840	=item $current_path = $w->path
199		841
200	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	842	=item $old_path = $w->path ($new_path)
201		843
202	=back	844	Returns the previously set path and optionally set a new one.
203		845
204	=head1 BUGS	846	=item $current_interval = $w->interval
205		847
206	Lots. Libevent itself isn't well tested and rather buggy, and this module	848	=item $old_interval = $w->interval ($new_interval)
207	is quite new at the moment.	849
		850	Returns the previously set interval and optionally set a new one. Can be
		851	used to query the actual interval used.
		852
		853	=back
		854
		855
		856	=head3 IDLE WATCHERS - when you've got nothing better to do...
		857
		858	=over 4
		859
		860	=item $w = EV::idle $callback
		861
		862	=item $w = EV::idle_ns $callback
		863
		864	=item $w = $loop->idle ($callback)
		865
		866	=item $w = $loop->idle_ns ($callback)
		867
		868	Call the callback when there are no other pending watchers of the same or
		869	higher priority (excluding check, prepare and other idle watchers of the
		870	same or lower priority, of course). They are called idle watchers because
		871	when the watcher is the highest priority pending event in the process, the
		872	process is considered to be idle at that priority.
		873
		874	If you want a watcher that is only ever called when I<no> other events are
		875	outstanding you have to set the priority to C<EV::MINPRI>.
		876
		877	The process will not block as long as any idle watchers are active, and
		878	they will be called repeatedly until stopped.
		879
		880	For example, if you have idle watchers at priority C<0> and C<1>, and
		881	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		882	and the I/O watcher will always run when ready. Only when the idle watcher
		883	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		884	pending with the C<0>-priority idle watcher be invoked.
		885
		886	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		887
		888	=back
		889
		890
		891	=head3 PREPARE WATCHERS - customise your event loop!
		892
		893	=over 4
		894
		895	=item $w = EV::prepare $callback
		896
		897	=item $w = EV::prepare_ns $callback
		898
		899	=item $w = $loop->prepare ($callback)
		900
		901	=item $w = $loop->prepare_ns ($callback)
		902
		903	Call the callback just before the process would block. You can still
		904	create/modify any watchers at this point.
		905
		906	See the EV::check watcher, below, for explanations and an example.
		907
		908	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		909
		910	=back
		911
		912
		913	=head3 CHECK WATCHERS - customise your event loop even more!
		914
		915	=over 4
		916
		917	=item $w = EV::check $callback
		918
		919	=item $w = EV::check_ns $callback
		920
		921	=item $w = $loop->check ($callback)
		922
		923	=item $w = $loop->check_ns ($callback)
		924
		925	Call the callback just after the process wakes up again (after it has
		926	gathered events), but before any other callbacks have been invoked.
		927
		928	This is used to integrate other event-based software into the EV
		929	mainloop: You register a prepare callback and in there, you create io and
		930	timer watchers as required by the other software. Here is a real-world
		931	example of integrating Net::SNMP (with some details left out):
		932
		933	our @snmp_watcher;
		934
		935	our $snmp_prepare = EV::prepare sub {
		936	# do nothing unless active
		937	$dispatcher->{_event_queue_h}
		938	or return;
		939
		940	# make the dispatcher handle any outstanding stuff
		941	... not shown
		942
		943	# create an I/O watcher for each and every socket
		944	@snmp_watcher = (
		945	(map { EV::io $_, EV::READ, sub { } }
		946	keys %{ $dispatcher->{_descriptors} }),
		947
		948	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		949	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		950	0, sub { },
		951	);
		952	};
		953
		954	The callbacks are irrelevant (and are not even being called), the
		955	only purpose of those watchers is to wake up the process as soon as
		956	one of those events occurs (socket readable, or timer timed out). The
		957	corresponding EV::check watcher will then clean up:
		958
		959	our $snmp_check = EV::check sub {
		960	# destroy all watchers
		961	@snmp_watcher = ();
		962
		963	# make the dispatcher handle any new stuff
		964	... not shown
		965	};
		966
		967	The callbacks of the created watchers will not be called as the watchers
		968	are destroyed before this can happen (remember EV::check gets called
		969	first).
		970
		971	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		972
		973	=back
		974
		975
		976	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		977
		978	Fork watchers are called when a C<fork ()> was detected. The invocation
		979	is done before the event loop blocks next and before C<check> watchers
		980	are being called, and only in the child after the fork.
		981
		982	=over 4
		983
		984	=item $w = EV::fork $callback
		985
		986	=item $w = EV::fork_ns $callback
		987
		988	=item $w = $loop->fork ($callback)
		989
		990	=item $w = $loop->fork_ns ($callback)
		991
		992	Call the callback before the event loop is resumed in the child process
		993	after a fork.
		994
		995	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		996
		997	=back
		998
		999
		1000	=head3 EMBED WATCHERS - when one backend isn't enough...
		1001
		1002	This is a rather advanced watcher type that lets you embed one event loop
		1003	into another (currently only IO events are supported in the embedded
		1004	loop, other types of watchers might be handled in a delayed or incorrect
		1005	fashion and must not be used).
		1006
		1007	See the libev documentation at
		1008	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1009	(locally installed as F<EV::libev>) for more details.
		1010
		1011	In short, this watcher is most useful on BSD systems without working
		1012	kqueue to still be able to handle a large number of sockets:
		1013
		1014	my $socket_loop;
		1015
		1016	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1017	if (
		1018	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1019	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1020	) {
		1021	# use kqueue for sockets
		1022	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1023	}
		1024
		1025	# use the default loop otherwise
		1026	$socket_loop \|\|= EV::default_loop;
		1027
		1028	=over 4
		1029
		1030	=item $w = EV::embed $otherloop[, $callback]
		1031
		1032	=item $w = EV::embed_ns $otherloop[, $callback]
		1033
		1034	=item $w = $loop->embed ($otherloop[, $callback])
		1035
		1036	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1037
		1038	Call the callback when the embedded event loop (C<$otherloop>) has any
		1039	I/O activity. The C<$callback> is optional: if it is missing, then the
		1040	embedded event loop will be managed automatically (which is recommended),
		1041	otherwise you have to invoke C<sweep> yourself.
		1042
		1043	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1044
		1045	=back
		1046
		1047	=head3 ASYNC WATCHERS - how to wake up another event loop
		1048
		1049	Async watchers are provided by EV, but have little use in perl directly,
		1050	as perl neither supports threads running in parallel nor direct access to
		1051	signal handlers or other contexts where they could be of value.
		1052
		1053	It is, however, possible to use them from the XS level.
		1054
		1055	Please see the libev documentation for further details.
		1056
		1057	=over 4
		1058
		1059	=item $w = EV::async $callback
		1060
		1061	=item $w = EV::async_ns $callback
		1062
		1063	=item $w->send
		1064
		1065	=item $bool = $w->async_pending
		1066
		1067	=back
		1068
		1069
		1070	=head1 PERL SIGNALS
		1071
		1072	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1073	with EV is as the same as any other C library: Perl-signals will only be
		1074	handled when Perl runs, which means your signal handler might be invoked
		1075	only the next time an event callback is invoked.
		1076
		1077	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1078	ensure proper operations with regards to other event watchers.
		1079
		1080	If you cannot do this for whatever reason, you can also force a watcher
		1081	to be called on every event loop iteration by installing a C<EV::check>
		1082	watcher:
		1083
		1084	my $async_check = EV::check sub { };
		1085
		1086	This ensures that perl gets into control for a short time to handle any
		1087	pending signals, and also ensures (slightly) slower overall operation.
		1088
		1089	=head1 ITHREADS
		1090
		1091	Ithreads are not supported by this module in any way. Perl pseudo-threads
		1092	is evil stuff and must die. Real threads as provided by Coro are fully
		1093	supported (and enhanced support is available via L<Coro::EV>).
		1094
		1095	=head1 FORK
		1096
		1097	Most of the "improved" event delivering mechanisms of modern operating
		1098	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1099	not supported and usually destructive). Libev makes it possible to work
		1100	around this by having a function that recreates the kernel state after
		1101	fork in the child.
		1102
		1103	On non-win32 platforms, this module requires the pthread_atfork
		1104	functionality to do this automatically for you. This function is quite
		1105	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1106	negligible, because everything the function currently does is set a flag
		1107	that is checked only when the event loop gets used the next time, so when
		1108	you do fork but not use EV, the overhead is minimal.
		1109
		1110	On win32, there is no notion of fork so all this doesn't apply, of course.
208		1111
209	=cut	1112	=cut
210		1113
211	our $NPRI = 4;	1114	our $DIED = sub {
212	our $BASE = init;	1115	warn "EV: error in callback (ignoring): $@";
213	priority_init $NPRI;	1116	};
		1117
		1118	default_loop
		1119	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
214		1120
215	1;	1121	1;
216		1122
		1123	=head1 SEE ALSO
		1124
		1125	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
		1126	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1127	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1128	event-loop agnostic and portable event driven programming.
		1129
217	=head1 AUTHOR	1130	=head1 AUTHOR
218		1131
219	Marc Lehmann <schmorp@schmorp.de>	1132	Marc Lehmann <schmorp@schmorp.de>
220	http://home.schmorp.de/	1133	http://home.schmorp.de/
221		1134
222	=cut	1135	=cut
223		1136

Diff Legend

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

Comparing EV/EV.pm (file contents): Revision 1.2 by root, Fri Oct 26 17:24:17 2007 UTC vs. Revision 1.116 by root, Sat Jun 13 15:11:54 2009 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.2 by root, Fri Oct 26 17:24:17 2007 UTC vs.
Revision 1.116 by root, Sat Jun 13 15:11:54 2009 UTC