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

Comparing EV/EV.pm (file contents):
Revision 1.8 by root, Sat Oct 27 19:11:27 2007 UTC vs.
Revision 1.65 by root, Sat Dec 8 14:12:03 2007 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothign received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};	30	};
35	$w->timeout (10);	31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
36		39
		40	my $w = EV::child 666, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
		44
		45	# STAT CHANGES
		46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
		49	};
		50
37	# MAINLOOP	51	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		55
43	=head1 DESCRIPTION	56	=head1 DESCRIPTION
44		57
45	This module provides an interface to libevent	58	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
47	yourself with its documentation and source code to be able to use this	60	below is comprehensive, one might also consult the documentation of libev
48	module fully.	61	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
49		62	watcher semantics or some discussion on the available backends, or how to
50	Please note thta this module disables the libevent EPOLL method by	63	force a specific backend with C<LIBEV_FLAGS>, or just about in any case
51	default, see BUGS, below, if you need to enable it.	64	because it has much more detailed information.
52		65
53	=cut	66	=cut
54		67
55	package EV;	68	package EV;
56		69
57	use strict;	70	use strict;
58		71
59	BEGIN {	72	BEGIN {
60	our $VERSION = '0.01';	73	our $VERSION = '1.8';
61	use XSLoader;	74	use XSLoader;
62	XSLoader::load "EV", $VERSION;	75	XSLoader::load "EV", $VERSION;
63	}	76	}
64		77
		78	@EV::IO::ISA =
		79	@EV::Timer::ISA =
		80	@EV::Periodic::ISA =
		81	@EV::Signal::ISA =
		82	@EV::Child::ISA =
		83	@EV::Stat::ISA =
		84	@EV::Idle::ISA =
		85	@EV::Prepare::ISA =
		86	@EV::Check::ISA =
		87	@EV::Embed::ISA =
		88	@EV::Fork::ISA =
		89	"EV::Watcher";
		90
65	=head1 BASIC INTERFACE	91	=head1 BASIC INTERFACE
66		92
67	=over 4	93	=over 4
68
69	=item $EV::NPRI
70
71	How many priority levels are available.
72		94
73	=item $EV::DIED	95	=item $EV::DIED
74		96
75	Must contain a reference to a function that is called when a callback	97	Must contain a reference to a function that is called when a callback
76	throws an exception (with $@ containing thr error). The default prints an	98	throws an exception (with $@ containing thr error). The default prints an
77	informative message and continues.	99	informative message and continues.
78		100
79	If this callback throws an exception it will be silently ignored.	101	If this callback throws an exception it will be silently ignored.
80		102
		103	=item $time = EV::time
		104
		105	Returns the current time in (fractional) seconds since the epoch.
		106
81	=item $time = EV::now	107	=item $time = EV::now
82		108
83	Returns the time in (fractional) seconds since the epoch.	109	Returns the time the last event loop iteration has been started. This
84		110	is the time that (relative) timers are based on, and refering to it is
85	=item $version = EV::version	111	usually faster then calling EV::time.
86		112
87	=item $method = EV::method	113	=item $method = EV::method
88		114
89	Return version string and event polling method used.	115	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		116	or EV::METHOD_EPOLL).
90		117
91	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	118	=item EV::loop [$flags]
92		119
93	=item EV::loopexit $after	120	Begin checking for events and calling callbacks. It returns when a
		121	callback calls EV::unloop.
94		122
95	Exit any active loop or dispatch after C<$after> seconds or immediately if	123	The $flags argument can be one of the following:
96	C<$after> is missing or zero.
97		124
98	=item EV::dispatch	125	0 as above
		126	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		127	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
99		128
100	Same as C<EV::loop 0>.	129	=item EV::unloop [$how]
101		130
102	=item EV::event $callback	131	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		132	innermost call to EV::loop return.
103		133
104	Creates a new event watcher waiting for nothing, calling the given callback.	134	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		135	fast as possible.
105		136
		137	=item $count = EV::loop_count
		138
		139	Return the number of times the event loop has polled for new
		140	events. Sometiems useful as a generation counter.
		141
		142	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		143
		144	This function rolls together an I/O and a timer watcher for a single
		145	one-shot event without the need for managing a watcher object.
		146
		147	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		148	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		149	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		150	you do not want to wait for some I/O event, specify C<undef> for
		151	C<$fh_or_undef> and C<0> for C<$events>).
		152
		153	If timeout is C<undef> or negative, then there will be no
		154	timeout. Otherwise a EV::timer with this value will be started.
		155
		156	When an error occurs or either the timeout or I/O watcher triggers, then
		157	the callback will be called with the received event set (in general
		158	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		159	C<EV::WRITE> and C<EV::TIMEOUT>).
		160
		161	EV::once doesn't return anything: the watchers stay active till either
		162	of them triggers, then they will be stopped and freed, and the callback
		163	invoked.
		164
		165	=item EV::feed_fd_event ($fd, $revents)
		166
		167	Feed an event on a file descriptor into EV. EV will react to this call as
		168	if the readyness notifications specified by C<$revents> (a combination of
		169	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		170
		171	=item EV::feed_signal_event ($signal)
		172
		173	Feed a signal event into EV. EV will react to this call as if the signal
		174	specified by C<$signal> had occured.
		175
		176	=back
		177
		178
		179	=head2 WATCHER OBJECTS
		180
		181	A watcher is an object that gets created to record your interest in some
		182	event. For instance, if you want to wait for STDIN to become readable, you
		183	would create an EV::io watcher for that:
		184
		185	my $watcher = EV::io *STDIN, EV::READ, sub {
		186	my ($watcher, $revents) = @_;
		187	warn "yeah, STDIN should not be readable without blocking!\n"
		188	};
		189
		190	All watchers can be active (waiting for events) or inactive (paused). Only
		191	active watchers will have their callbacks invoked. All callbacks will be
		192	called with at least two arguments: the watcher and a bitmask of received
		193	events.
		194
		195	Each watcher type has its associated bit in revents, so you can use the
		196	same callback for multiple watchers. The event mask is named after the
		197	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		198	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		199	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		200	uses EV::TIMEOUT).
		201
		202	In the rare case where one wants to create a watcher but not start it at
		203	the same time, each constructor has a variant with a trailing C<_ns> in
		204	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		205
		206	Please note that a watcher will automatically be stopped when the watcher
		207	object is destroyed, so you I<need> to keep the watcher objects returned by
		208	the constructors.
		209
		210	Also, all methods changing some aspect of a watcher (->set, ->priority,
		211	->fh and so on) automatically stop and start it again if it is active,
		212	which means pending events get lost.
		213
		214	=head2 COMMON WATCHER METHODS
		215
		216	This section lists methods common to all watchers.
		217
		218	=over 4
		219
		220	=item $w->start
		221
		222	Starts a watcher if it isn't active already. Does nothing to an already
		223	active watcher. By default, all watchers start out in the active state
		224	(see the description of the C<_ns> variants if you need stopped watchers).
		225
		226	=item $w->stop
		227
		228	Stop a watcher if it is active. Also clear any pending events (events that
		229	have been received but that didn't yet result in a callback invocation),
		230	regardless of whether the watcher was active or not.
		231
		232	=item $bool = $w->is_active
		233
		234	Returns true if the watcher is active, false otherwise.
		235
		236	=item $current_data = $w->data
		237
		238	=item $old_data = $w->data ($new_data)
		239
		240	Queries a freely usable data scalar on the watcher and optionally changes
		241	it. This is a way to associate custom data with a watcher:
		242
		243	my $w = EV::timer 60, 0, sub {
		244	warn $_[0]->data;
		245	};
		246	$w->data ("print me!");
		247
		248	=item $current_cb = $w->cb
		249
		250	=item $old_cb = $w->cb ($new_cb)
		251
		252	Queries the callback on the watcher and optionally changes it. You can do
		253	this at any time without the watcher restarting.
		254
		255	=item $current_priority = $w->priority
		256
		257	=item $old_priority = $w->priority ($new_priority)
		258
		259	Queries the priority on the watcher and optionally changes it. Pending
		260	watchers with higher priority will be invoked first. The valid range of
		261	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		262	-2). If the priority is outside this range it will automatically be
		263	normalised to the nearest valid priority.
		264
		265	The default priority of any newly-created watcher is 0.
		266
		267	Note that the priority semantics have not yet been fleshed out and are
		268	subject to almost certain change.
		269
		270	=item $w->invoke ($revents)
		271
		272	Call the callback now with the given event mask.
		273
		274	=item $w->feed_event ($revents)
		275
		276	Feed some events on this watcher into EV. EV will react to this call as if
		277	the watcher had received the given C<$revents> mask.
		278
		279	=item $revents = $w->clear_pending
		280
		281	If the watcher is pending, this function returns clears its pending status
		282	and returns its C<$revents> bitset (as if its callback was invoked). If the
		283	watcher isn't pending it does nothing and returns C<0>.
		284
		285	=item $previous_state = $w->keepalive ($bool)
		286
		287	Normally, C<EV::loop> will return when there are no active watchers
		288	(which is a "deadlock" because no progress can be made anymore). This is
		289	convinient because it allows you to start your watchers (and your jobs),
		290	call C<EV::loop> once and when it returns you know that all your jobs are
		291	finished (or they forgot to register some watchers for their task :).
		292
		293	Sometimes, however, this gets in your way, for example when you the module
		294	that calls C<EV::loop> (usually the main program) is not the same module
		295	as a long-living watcher (for example a DNS client module written by
		296	somebody else even). Then you might want any outstanding requests to be
		297	handled, but you would not want to keep C<EV::loop> from returning just
		298	because you happen to have this long-running UDP port watcher.
		299
		300	In this case you can clear the keepalive status, which means that even
		301	though your watcher is active, it won't keep C<EV::loop> from returning.
		302
		303	The initial value for keepalive is true (enabled), and you cna change it
		304	any time.
		305
		306	Example: Register an I/O watcher for some UDP socket but do not keep the
		307	event loop from running just because of that watcher.
		308
		309	my $udp_socket = ...
		310	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		311	$udp_watcher->keepalive (0);
		312
		313	=back
		314
		315
		316	=head2 WATCHER TYPES
		317
		318	Each of the following subsections describes a single watcher type.
		319
		320	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		321
		322	=over 4
		323
106	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	324	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
107		325
108	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	326	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
109		327
110	As long as the returned watcher object is alive, call the C<$callback>	328	As long as the returned watcher object is alive, call the C<$callback>
111	when the events specified in C<$eventmask> happen. Initially, the timeout	329	when at least one of events specified in C<$eventmask> occurs.
112	is disabled.
113		330
114	Youc an additionall set a timeout to occur on the watcher, but note that
115	this timeout will not be reset when you get an I/O event in the EV::PERSIST
116	case, and reaching a timeout will always stop the watcher even in the
117	EV::PERSIST case.
118
119	If you want a timeout to occur only after a specific time of inactivity, set
120	a repeating timeout and do NOT use EV::PERSIST.
121
122	Eventmask can be one or more of these constants ORed together:	331	The $eventmask can be one or more of these constants ORed together:
123		332
124	EV::READ wait until read() wouldn't block anymore	333	EV::READ wait until read() wouldn't block anymore
125	EV::WRITE wait until write() wouldn't block anymore	334	EV::WRITE wait until write() wouldn't block anymore
126	EV::PERSIST stay active after a (non-timeout) event occured
127		335
128	The C<io_ns> variant doesn't add/start the newly created watcher.	336	The C<io_ns> variant doesn't start (activate) the newly created watcher.
129		337
		338	=item $w->set ($fileno_or_fh, $eventmask)
		339
		340	Reconfigures the watcher, see the constructor above for details. Can be
		341	called at any time.
		342
		343	=item $current_fh = $w->fh
		344
		345	=item $old_fh = $w->fh ($new_fh)
		346
		347	Returns the previously set filehandle and optionally set a new one.
		348
		349	=item $current_eventmask = $w->events
		350
		351	=item $old_eventmask = $w->events ($new_eventmask)
		352
		353	Returns the previously set event mask and optionally set a new one.
		354
		355	=back
		356
		357
		358	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		359
		360	=over 4
		361
130	=item my $w = EV::timer $after, $repeat, $callback	362	=item $w = EV::timer $after, $repeat, $callback
131		363
132	=item my $w = EV::timer_ns $after, $repeat, $callback	364	=item $w = EV::timer_ns $after, $repeat, $callback
133		365
134	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	366	Calls the callback after C<$after> seconds (which may be fractional). If
135	timer will be restarted after the callback returns. This means that the	367	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
136	callback would be called roughly every C<$after> seconds, prolonged by the	368	value as $after) after the callback returns.
137	time the callback takes.
138		369
		370	This means that the callback would be called roughly after C<$after>
		371	seconds, and then every C<$repeat> seconds. The timer does his best not
		372	to drift, but it will not invoke the timer more often then once per event
		373	loop iteration, and might drift in other cases. If that isn't acceptable,
		374	look at EV::periodic, which can provide long-term stable timers.
		375
		376	The timer is based on a monotonic clock, that is, if somebody is sitting
		377	in front of the machine while the timer is running and changes the system
		378	clock, the timer will nevertheless run (roughly) the same time.
		379
139	The C<timer_ns> variant doesn't add/start the newly created watcher.	380	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
140		381
141	=item my $w = EV::timer_abs $at, $interval, $callback	382	=item $w->set ($after, $repeat)
142		383
143	=item my $w = EV::timer_abs_ns $at, $interval, $callback	384	Reconfigures the watcher, see the constructor above for details. Can be called at
		385	any time.
144		386
145	Similar to EV::timer, but the time is given as an absolute point in time	387	=item $w->again
146	(C<$at>), plus an optional C<$interval>.
147		388
148	If the C<$interval> is zero, then the callback will be called at the time	389	Similar to the C<start> method, but has special semantics for repeating timers:
149	C<$at> if that is in the future, or as soon as possible if its in the
150	past. It will not automatically repeat.
151		390
152	If the C<$interval> is nonzero, then the watcher will always be scheduled	391	If the timer is active and non-repeating, it will be stopped.
153	to time out at the next C<$at + integer * $interval> time.
154		392
155	This can be used to schedule a callback to run at very regular intervals,	393	If the timer is active and repeating, reset the timeout to occur
156	as long as the processing time is less then the interval (otherwise	394	C<$repeat> seconds after now.
157	obviously events will be skipped).	395
		396	If the timer is inactive and repeating, start it using the repeat value.
		397
		398	Otherwise do nothing.
		399
		400	This behaviour is useful when you have a timeout for some IO
		401	operation. You create a timer object with the same value for C<$after> and
		402	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		403	on the timeout.
		404
		405	=back
		406
		407
		408	=head3 PERIODIC WATCHERS - to cron or not to cron?
		409
		410	=over 4
		411
		412	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		413
		414	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		415
		416	Similar to EV::timer, but is not based on relative timeouts but on
		417	absolute times. Apart from creating "simple" timers that trigger "at" the
		418	specified time, it can also be used for non-drifting absolute timers and
		419	more complex, cron-like, setups that are not adversely affected by time
		420	jumps (i.e. when the system clock is changed by explicit date -s or other
		421	means such as ntpd). It is also the most complex watcher type in EV.
		422
		423	It has three distinct "modes":
		424
		425	=over 4
		426
		427	=item * absolute timer ($interval = $reschedule_cb = 0)
		428
		429	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		430	will not adjust when a time jump occurs, that is, if it is to be run
		431	at January 1st 2011 then it will run when the system time reaches or
		432	surpasses this time.
		433
		434	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		435
		436	In this mode the watcher will always be scheduled to time out at the
		437	next C<$at + N * $interval> time (for some integer N) and then repeat,
		438	regardless of any time jumps.
		439
		440	This can be used to create timers that do not drift with respect to system
		441	time:
		442
		443	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		444
		445	That doesn't mean there will always be 3600 seconds in between triggers,
		446	but only that the the clalback will be called when the system time shows a
		447	full hour (UTC).
158		448
159	Another way to think about it (for the mathematically inclined) is that	449	Another way to think about it (for the mathematically inclined) is that
160	C<timer_abs> will try to tun the callback at the next possible time where	450	EV::periodic will try to run the callback in this mode at the next
161	C<$time = $at (mod $interval)>, regardless of any time jumps.	451	possible time where C<$time = $at (mod $interval)>, regardless of any time
		452	jumps.
162		453
		454	=item * manual reschedule mode ($reschedule_cb = coderef)
		455
		456	In this mode $interval and $at are both being ignored. Instead, each
		457	time the periodic watcher gets scheduled, the reschedule callback
		458	($reschedule_cb) will be called with the watcher as first, and the current
		459	time as second argument.
		460
		461	I<This callback MUST NOT stop or destroy this or any other periodic
		462	watcher, ever>. If you need to stop it, return 1e30 and stop it
		463	afterwards.
		464
		465	It must return the next time to trigger, based on the passed time value
		466	(that is, the lowest time value larger than to the second argument). It
		467	will usually be called just before the callback will be triggered, but
		468	might be called at other times, too.
		469
		470	This can be used to create very complex timers, such as a timer that
		471	triggers on each midnight, local time (actually 24 hours after the last
		472	midnight, to keep the example simple. If you know a way to do it correctly
		473	in about the same space (without requiring elaborate modules), drop me a
		474	note :):
		475
		476	my $daily = EV::periodic 0, 0, sub {
		477	my ($w, $now) = @_;
		478
		479	use Time::Local ();
		480	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		481	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		482	}, sub {
		483	print "it's midnight or likely shortly after, now\n";
		484	};
		485
		486	=back
		487
163	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	488	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
164		489
		490	=item $w->set ($at, $interval, $reschedule_cb)
		491
		492	Reconfigures the watcher, see the constructor above for details. Can be called at
		493	any time.
		494
		495	=item $w->again
		496
		497	Simply stops and starts the watcher again.
		498
		499	=back
		500
		501
		502	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		503
		504	=over 4
		505
165	=item my $w = EV::signal $signum, $callback	506	=item $w = EV::signal $signal, $callback
166		507
167	=item my $w = EV::signal_ns $signum, $callback	508	=item $w = EV::signal_ns $signal, $callback
168		509
169	Call the callback when signal $signum is received.	510	Call the callback when $signal is received (the signal can be specified by
		511	number or by name, just as with C<kill> or C<%SIG>).
170		512
		513	EV will grab the signal for the process (the kernel only allows one
		514	component to receive a signal at a time) when you start a signal watcher,
		515	and removes it again when you stop it. Perl does the same when you
		516	add/remove callbacks to C<%SIG>, so watch out.
		517
		518	You can have as many signal watchers per signal as you want.
		519
171	The C<signal_ns> variant doesn't add/start the newly created watcher.	520	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
172		521
173	=back	522	=item $w->set ($signal)
174		523
175	=head1 THE EV::Event CLASS	524	Reconfigures the watcher, see the constructor above for details. Can be
		525	called at any time.
176		526
177	All EV functions creating an event watcher (designated by C<my $w =>	527	=item $current_signum = $w->signal
178	above) support the following methods on the returned watcher object:
179		528
180	=over 4	529	=item $old_signum = $w->signal ($new_signal)
181		530
182	=item $w->add ($timeout)	531	Returns the previously set signal (always as a number not name) and
		532	optionally set a new one.
183		533
184	Stops and (re-)starts the event watcher, setting the optional timeout to	534	=back
185	the given value, or clearing the timeout if none is given.
186		535
		536
		537	=head3 CHILD WATCHERS - watch out for process status changes
		538
		539	=over 4
		540
		541	=item $w = EV::child $pid, $callback
		542
		543	=item $w = EV::child_ns $pid, $callback
		544
		545	Call the callback when a status change for pid C<$pid> (or any pid if
		546	C<$pid> is 0) has been received. More precisely: when the process receives
		547	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		548	changed/zombie children and call the callback.
		549
		550	It is valid (and fully supported) to install a child watcher after a child
		551	has exited but before the event loop has started its next iteration (for
		552	example, first you C<fork>, then the new child process might exit, and
		553	only then do you install a child watcher in the parent for the new pid).
		554
		555	You can access both exit (or tracing) status and pid by using the
		556	C<rstatus> and C<rpid> methods on the watcher object.
		557
		558	You can have as many pid watchers per pid as you want, they will all be
		559	called.
		560
		561	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		562
		563	=item $w->set ($pid)
		564
		565	Reconfigures the watcher, see the constructor above for details. Can be called at
		566	any time.
		567
		568	=item $current_pid = $w->pid
		569
		570	=item $old_pid = $w->pid ($new_pid)
		571
		572	Returns the previously set process id and optionally set a new one.
		573
		574	=item $exit_status = $w->rstatus
		575
		576	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		577	in perlfunc).
		578
		579	=item $pid = $w->rpid
		580
		581	Return the pid of the awaited child (useful when you have installed a
		582	watcher for all pids).
		583
		584	=back
		585
		586
		587	=head3 STAT WATCHERS - did the file attributes just change?
		588
		589	=over 4
		590
		591	=item $w = EV::stat $path, $interval, $callback
		592
		593	=item $w = EV::stat_ns $path, $interval, $callback
		594
		595	Call the callback when a file status change has been detected on
		596	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		597	to "path does not exist" is a status change like any other.
		598
		599	The C<$interval> is a recommended polling interval for systems where
		600	OS-supported change notifications don't exist or are not supported. If
		601	you use C<0> then an unspecified default is used (which is highly
		602	recommended!), which is to be expected to be around five seconds usually.
		603
		604	This watcher type is not meant for massive numbers of stat watchers,
		605	as even with OS-supported change notifications, this can be
		606	resource-intensive.
		607
		608	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		609
187	=item $w->start	610	=item ... = $w->stat
188		611
189	Stops and (re-)starts the event watcher without touching the timeout.	612	This call is very similar to the perl C<stat> built-in: It stats (using
		613	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		614	well as EV's idea of the current stat values) to the values found.
190		615
191	=item $w->del	616	In scalar context, a boolean is return indicating success or failure of
		617	the stat. In list context, the same 13-value list as with stat is returned
		618	(except that the blksize and blocks fields are not reliable).
192		619
193	=item $w->stop	620	In the case of an error, errno is set to C<ENOENT> (regardless of the
		621	actual error value) and the C<nlink> value is forced to zero (if the stat
		622	was successful then nlink is guaranteed to be non-zero).
194		623
195	Stop the event watcher if it was started.	624	See also the next two entries for more info.
196		625
197	=item $current_callback = $w->cb	626	=item ... = $w->attr
198		627
199	=item $old_callback = $w->cb ($new_callback)	628	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		629	the values most recently detected by EV. See the next entry for more info.
200		630
		631	=item ... = $w->prev
		632
		633	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		634	the previous set of values, before the change.
		635
		636	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		637	to the values found I<before> a change was detected, while C<< $w->attr >>
		638	returns the values found leading to the change detection. The difference (if any)
		639	between C<prev> and C<attr> is what triggered the callback.
		640
		641	If you did something to the filesystem object and do not want to trigger
		642	yet another change, you can call C<stat> to update EV's idea of what the
		643	current attributes are.
		644
		645	=item $w->set ($path, $interval)
		646
		647	Reconfigures the watcher, see the constructor above for details. Can be
		648	called at any time.
		649
		650	=item $current_path = $w->path
		651
		652	=item $old_path = $w->path ($new_path)
		653
201	Return the previously set callback and optionally set a new one.	654	Returns the previously set path and optionally set a new one.
202		655
203	=item $current_fh = $w->fh	656	=item $current_interval = $w->interval
204		657
205	=item $old_fh = $w->fh ($new_fh)	658	=item $old_interval = $w->interval ($new_interval)
206		659
207	Returns the previously set filehandle and optionally set a new one.
208
209	=item $current_eventmask = $w->events
210
211	=item $old_eventmask = $w->events ($new_eventmask)
212
213	Returns the previously set event mask and optionally set a new one.	660	Returns the previously set interval and optionally set a new one. Can be
		661	used to query the actual interval used.
214		662
215	=item $w->timeout ($after, $repeat)
216
217	Resets the timeout (see C<EV::timer> for details).
218
219	=item $w->timeout_abs ($at, $interval)
220
221	Resets the timeout (see C<EV::timer_abs> for details).
222
223	=item $w->priority_set ($priority)
224
225	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
226
227	=back	663	=back
228		664
229	=head1 BUGS
230		665
231	Lots. Libevent itself isn't well tested and rather buggy, and this module	666	=head3 IDLE WATCHERS - when you've got nothing better to do...
232	is quite new at the moment.
233		667
234	Please note that the epoll method is not, in general, reliable in programs	668	=over 4
235	that use fork (even if no libveent calls are being made in the forked
236	process). If your program behaves erratically, try setting the environment
237	variable C<EVENT_NOEPOLL> first when running the program.
238		669
239	In general, if you fork, then you can only use the EV module in one of the	670	=item $w = EV::idle $callback
240	children.	671
		672	=item $w = EV::idle_ns $callback
		673
		674	Call the callback when there are no other pending watchers of the same or
		675	higher priority (excluding check, prepare and other idle watchers of the
		676	same or lower priority, of course). They are called idle watchers because
		677	when the watcher is the highest priority pending event in the process, the
		678	process is considered to be idle at that priority.
		679
		680	If you want a watcher that is only ever called when I<no> other events are
		681	outstanding you have to set the priority to C<EV::MINPRI>.
		682
		683	The process will not block as long as any idle watchers are active, and
		684	they will be called repeatedly until stopped.
		685
		686	For example, if you have idle watchers at priority C<0> and C<1>, and
		687	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		688	and the I/O watcher will always run when ready. Only when the idle watcher
		689	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		690	pending with the C<0>-priority idle watcher be invoked.
		691
		692	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		693
		694	=back
		695
		696
		697	=head3 PREPARE WATCHERS - customise your event loop!
		698
		699	=over 4
		700
		701	=item $w = EV::prepare $callback
		702
		703	=item $w = EV::prepare_ns $callback
		704
		705	Call the callback just before the process would block. You can still
		706	create/modify any watchers at this point.
		707
		708	See the EV::check watcher, below, for explanations and an example.
		709
		710	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		711
		712	=back
		713
		714
		715	=head3 CHECK WATCHERS - customise your event loop even more!
		716
		717	=over 4
		718
		719	=item $w = EV::check $callback
		720
		721	=item $w = EV::check_ns $callback
		722
		723	Call the callback just after the process wakes up again (after it has
		724	gathered events), but before any other callbacks have been invoked.
		725
		726	This is used to integrate other event-based software into the EV
		727	mainloop: You register a prepare callback and in there, you create io and
		728	timer watchers as required by the other software. Here is a real-world
		729	example of integrating Net::SNMP (with some details left out):
		730
		731	our @snmp_watcher;
		732
		733	our $snmp_prepare = EV::prepare sub {
		734	# do nothing unless active
		735	$dispatcher->{_event_queue_h}
		736	or return;
		737
		738	# make the dispatcher handle any outstanding stuff
		739	... not shown
		740
		741	# create an I/O watcher for each and every socket
		742	@snmp_watcher = (
		743	(map { EV::io $_, EV::READ, sub { } }
		744	keys %{ $dispatcher->{_descriptors} }),
		745
		746	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		747	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		748	0, sub { },
		749	);
		750	};
		751
		752	The callbacks are irrelevant (and are not even being called), the
		753	only purpose of those watchers is to wake up the process as soon as
		754	one of those events occurs (socket readable, or timer timed out). The
		755	corresponding EV::check watcher will then clean up:
		756
		757	our $snmp_check = EV::check sub {
		758	# destroy all watchers
		759	@snmp_watcher = ();
		760
		761	# make the dispatcher handle any new stuff
		762	... not shown
		763	};
		764
		765	The callbacks of the created watchers will not be called as the watchers
		766	are destroyed before this cna happen (remember EV::check gets called
		767	first).
		768
		769	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		770
		771	=back
		772
		773
		774	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		775
		776	Fork watchers are called when a C<fork ()> was detected. The invocation
		777	is done before the event loop blocks next and before C<check> watchers
		778	are being called, and only in the child after the fork.
		779
		780	=over 4
		781
		782	=item $w = EV::fork $callback
		783
		784	=item $w = EV::fork_ns $callback
		785
		786	Call the callback before the event loop is resumed in the child process
		787	after a fork.
		788
		789	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		790
		791	=back
		792
		793
		794	=head1 PERL SIGNALS
		795
		796	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		797	with EV is as the same as any other C library: Perl-signals will only be
		798	handled when Perl runs, which means your signal handler might be invoked
		799	only the next time an event callback is invoked.
		800
		801	The solution is to use EV signal watchers (see C<EV::signal>), which will
		802	ensure proper operations with regards to other event watchers.
		803
		804	If you cannot do this for whatever reason, you can also force a watcher
		805	to be called on every event loop iteration by installing a C<EV::check>
		806	watcher:
		807
		808	my $async_check = EV::check sub { };
		809
		810	This ensures that perl shortly gets into control for a short time, and
		811	also ensures slower overall operation.
		812
		813	=head1 THREADS
		814
		815	Threads are not supported by this module in any way. Perl pseudo-threads
		816	is evil stuff and must die. As soon as Perl gains real threads I will work
		817	on thread support for it.
		818
		819	=head1 FORK
		820
		821	Most of the "improved" event delivering mechanisms of modern operating
		822	systems have quite a few problems with fork(2) (to put it bluntly: it is
		823	not supported and usually destructive). Libev makes it possible to work
		824	around this by having a function that recreates the kernel state after
		825	fork in the child.
		826
		827	On non-win32 platforms, this module requires the pthread_atfork
		828	functionality to do this automatically for you. This function is quite
		829	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		830	negligible, because everything the function currently does is set a flag
		831	that is checked only when the event loop gets used the next time, so when
		832	you do fork but not use EV, the overhead is minimal.
		833
		834	On win32, there is no notion of fork so all this doesn't apply, of course.
241		835
242	=cut	836	=cut
243		837
244	our $DIED = sub {	838	our $DIED = sub {
245	warn "EV: error in callback (ignoring): $@";	839	warn "EV: error in callback (ignoring): $@";
246	};	840	};
247		841
248	our $NPRI = 4;	842	default_loop
249	our $BASE = init;	843	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
250	priority_init $NPRI;
251
252	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
253		844
254	1;	845	1;
255		846
256	=head1 SEE ALSO	847	=head1 SEE ALSO
257		848
258	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	849	L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
259	L<EV::AnyEvent>.	850	event loop), L<Coro::EV> (efficient coroutines with EV).
260		851
261	=head1 AUTHOR	852	=head1 AUTHOR
262		853
263	Marc Lehmann <schmorp@schmorp.de>	854	Marc Lehmann <schmorp@schmorp.de>
264	http://home.schmorp.de/	855	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.8 by root, Sat Oct 27 19:11:27 2007 UTC vs. Revision 1.65 by root, Sat Dec 8 14:12:03 2007 UTC

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Revision 1.8 by root, Sat Oct 27 19:11:27 2007 UTC vs.
Revision 1.65 by root, Sat Dec 8 14:12:03 2007 UTC