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

Comparing EV/EV.pm (file contents):
Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs.
Revision 1.61 by root, Thu Dec 6 03:13:07 2007 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothign received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};	30	};
35	$w->timeout (10);	31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
36		39
		40	my $w = EV::child 666, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
		44
		45	# STAT CHANGES
		46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
		49	};
		50
37	# MAINLOOP	51	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		55
43	=head1 DESCRIPTION	56	=head1 DESCRIPTION
44		57
45	This module provides an interface to libevent	58	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>).	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		60	below is comprehensive, one might also consult the documentation of libev
		61	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
		62	watcher semantics or some discussion on the available backends, or how to
		63	force a specific backend with C<LIBEV_FLAGS>.
47		64
48	=cut	65	=cut
49		66
50	package EV;	67	package EV;
51		68
52	use strict;	69	use strict;
53		70
54	BEGIN {	71	BEGIN {
55	our $VERSION = '0.01';	72	our $VERSION = '1.6';
56	use XSLoader;	73	use XSLoader;
57	XSLoader::load "EV", $VERSION;	74	XSLoader::load "EV", $VERSION;
58	}	75	}
59		76
60	=head1 FUNCTIONAL INTERFACE	77	@EV::IO::ISA =
		78	@EV::Timer::ISA =
		79	@EV::Periodic::ISA =
		80	@EV::Signal::ISA =
		81	@EV::Child::ISA =
		82	@EV::Stat::ISA =
		83	@EV::Idle::ISA =
		84	@EV::Prepare::ISA =
		85	@EV::Check::ISA =
		86	@EV::Embed::ISA =
		87	@EV::Fork::ISA =
		88	"EV::Watcher";
61		89
62	=over 4	90	=head1 BASIC INTERFACE
63		91
		92	=over 4
		93
64	=item $EV::NPRI	94	=item $EV::DIED
65		95
66	How many priority levels are available.	96	Must contain a reference to a function that is called when a callback
		97	throws an exception (with $@ containing thr error). The default prints an
		98	informative message and continues.
		99
		100	If this callback throws an exception it will be silently ignored.
		101
		102	=item $time = EV::time
		103
		104	Returns the current time in (fractional) seconds since the epoch.
67		105
68	=item $time = EV::now	106	=item $time = EV::now
69		107
70	Returns the time in (fractional) seconds since the epoch.	108	Returns the time the last event loop iteration has been started. This
71		109	is the time that (relative) timers are based on, and refering to it is
72	=item $version = EV::version	110	usually faster then calling EV::time.
73		111
74	=item $method = EV::method	112	=item $method = EV::method
75		113
76	Return version string and event polling method used.	114	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		115	or EV::METHOD_EPOLL).
77		116
78	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	117	=item EV::loop [$flags]
79		118
80	=item EV::loopexit $after	119	Begin checking for events and calling callbacks. It returns when a
		120	callback calls EV::unloop.
81		121
82	Exit any active loop or dispatch after C<$after> seconds or immediately if	122	The $flags argument can be one of the following:
83	C<$after> is missing or zero.
84		123
85	=item EV::dispatch	124	0 as above
		125	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		126	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
86		127
87	Same as C<EV::loop 0>.	128	=item EV::unloop [$how]
88		129
89	=item EV::event $callback	130	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		131	innermost call to EV::loop return.
90		132
91	Creates a new event watcher waiting for nothing, calling the given callback.	133	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		134	fast as possible.
92		135
		136	=item $count = EV::loop_count
		137
		138	Return the number of times the event loop has polled for new
		139	events. Sometiems useful as a generation counter.
		140
		141	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		142
		143	This function rolls together an I/O and a timer watcher for a single
		144	one-shot event without the need for managing a watcher object.
		145
		146	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		147	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		148	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		149	you do not want to wait for some I/O event, specify C<undef> for
		150	C<$fh_or_undef> and C<0> for C<$events>).
		151
		152	If timeout is C<undef> or negative, then there will be no
		153	timeout. Otherwise a EV::timer with this value will be started.
		154
		155	When an error occurs or either the timeout or I/O watcher triggers, then
		156	the callback will be called with the received event set (in general
		157	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		158	C<EV::WRITE> and C<EV::TIMEOUT>).
		159
		160	EV::once doesn't return anything: the watchers stay active till either
		161	of them triggers, then they will be stopped and freed, and the callback
		162	invoked.
		163
		164	=back
		165
		166	=head2 WATCHER OBJECTS
		167
		168	A watcher is an object that gets created to record your interest in some
		169	event. For instance, if you want to wait for STDIN to become readable, you
		170	would create an EV::io watcher for that:
		171
		172	my $watcher = EV::io *STDIN, EV::READ, sub {
		173	my ($watcher, $revents) = @_;
		174	warn "yeah, STDIN should not be readable without blocking!\n"
		175	};
		176
		177	All watchers can be active (waiting for events) or inactive (paused). Only
		178	active watchers will have their callbacks invoked. All callbacks will be
		179	called with at least two arguments: the watcher and a bitmask of received
		180	events.
		181
		182	Each watcher type has its associated bit in revents, so you can use the
		183	same callback for multiple watchers. The event mask is named after the
		184	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		185	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		186	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		187	uses EV::TIMEOUT).
		188
		189	In the rare case where one wants to create a watcher but not start it at
		190	the same time, each constructor has a variant with a trailing C<_ns> in
		191	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		192
		193	Please note that a watcher will automatically be stopped when the watcher
		194	object is destroyed, so you I<need> to keep the watcher objects returned by
		195	the constructors.
		196
		197	Also, all methods changing some aspect of a watcher (->set, ->priority,
		198	->fh and so on) automatically stop and start it again if it is active,
		199	which means pending events get lost.
		200
		201	=head2 COMMON WATCHER METHODS
		202
		203	This section lists methods common to all watchers.
		204
		205	=over 4
		206
		207	=item $w->start
		208
		209	Starts a watcher if it isn't active already. Does nothing to an already
		210	active watcher. By default, all watchers start out in the active state
		211	(see the description of the C<_ns> variants if you need stopped watchers).
		212
		213	=item $w->stop
		214
		215	Stop a watcher if it is active. Also clear any pending events (events that
		216	have been received but that didn't yet result in a callback invocation),
		217	regardless of wether the watcher was active or not.
		218
		219	=item $bool = $w->is_active
		220
		221	Returns true if the watcher is active, false otherwise.
		222
		223	=item $current_data = $w->data
		224
		225	=item $old_data = $w->data ($new_data)
		226
		227	Queries a freely usable data scalar on the watcher and optionally changes
		228	it. This is a way to associate custom data with a watcher:
		229
		230	my $w = EV::timer 60, 0, sub {
		231	warn $_[0]->data;
		232	};
		233	$w->data ("print me!");
		234
		235	=item $current_cb = $w->cb
		236
		237	=item $old_cb = $w->cb ($new_cb)
		238
		239	Queries the callback on the watcher and optionally changes it. You can do
		240	this at any time without the watcher restarting.
		241
		242	=item $current_priority = $w->priority
		243
		244	=item $old_priority = $w->priority ($new_priority)
		245
		246	Queries the priority on the watcher and optionally changes it. Pending
		247	watchers with higher priority will be invoked first. The valid range of
		248	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		249	-2). If the priority is outside this range it will automatically be
		250	normalised to the nearest valid priority.
		251
		252	The default priority of any newly-created watcher is 0.
		253
		254	Note that the priority semantics have not yet been fleshed out and are
		255	subject to almost certain change.
		256
		257	=item $w->trigger ($revents)
		258
		259	Call the callback now with the given event mask.
		260
		261	=item $previous_state = $w->keepalive ($bool)
		262
		263	Normally, C<EV::loop> will return when there are no active watchers
		264	(which is a "deadlock" because no progress can be made anymore). This is
		265	convinient because it allows you to start your watchers (and your jobs),
		266	call C<EV::loop> once and when it returns you know that all your jobs are
		267	finished (or they forgot to register some watchers for their task :).
		268
		269	Sometimes, however, this gets in your way, for example when you the module
		270	that calls C<EV::loop> (usually the main program) is not the same module
		271	as a long-living watcher (for example a DNS client module written by
		272	somebody else even). Then you might want any outstanding requests to be
		273	handled, but you would not want to keep C<EV::loop> from returning just
		274	because you happen to have this long-running UDP port watcher.
		275
		276	In this case you can clear the keepalive status, which means that even
		277	though your watcher is active, it won't keep C<EV::loop> from returning.
		278
		279	The initial value for keepalive is true (enabled), and you cna change it
		280	any time.
		281
		282	Example: Register an IO watcher for some UDP socket but do not keep the
		283	event loop from running just because of that watcher.
		284
		285	my $udp_socket = ...
		286	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		287	$udp_watcher->keepalive (0);
		288
		289	=back
		290
		291
		292	=head2 WATCHER TYPES
		293
		294	Each of the following subsections describes a single watcher type.
		295
		296	=head3 IO WATCHERS - is this file descriptor readable or writable?
		297
		298	=over 4
		299
93	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	300	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
94		301
95	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	302	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
96		303
97	As long as the returned watcher object is alive, call the C<$callback>	304	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	305	when at least one of events specified in C<$eventmask> occurs.
99	is disabled.
100		306
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:	307	The $eventmask can be one or more of these constants ORed together:
104		308
105	EV::READ wait until read() wouldn't block anymore	309	EV::READ wait until read() wouldn't block anymore
106	EV::WRITE wait until write() wouldn't block anymore	310	EV::WRITE wait until write() wouldn't block anymore
107	EV::PERSIST stay active after an event occured
108		311
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.	312	The C<io_ns> variant doesn't start (activate) the newly created watcher.
119		313
120	=item my $w = EV::timer_abs $at, $interval, $callback	314	=item $w->set ($fileno_or_fh, $eventmask)
121		315
122	=item my $w = EV::timer_abs_ns $at, $interval, $callback	316	Reconfigures the watcher, see the constructor above for details. Can be
123		317	called at any time.
124	Similar to EV::timer, but the time is given as an absolute point in time
125	(C<$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		318
178	=item $current_fh = $w->fh	319	=item $current_fh = $w->fh
179		320
180	=item $old_fh = $w->fh ($new_fh)	321	=item $old_fh = $w->fh ($new_fh)
181		322
185		326
186	=item $old_eventmask = $w->events ($new_eventmask)	327	=item $old_eventmask = $w->events ($new_eventmask)
187		328
188	Returns the previously set event mask and optionally set a new one.	329	Returns the previously set event mask and optionally set a new one.
189		330
		331	=back
		332
		333
		334	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		335
		336	=over 4
		337
		338	=item $w = EV::timer $after, $repeat, $callback
		339
		340	=item $w = EV::timer_ns $after, $repeat, $callback
		341
		342	Calls the callback after C<$after> seconds (which may be fractional). If
		343	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		344	value as $after) after the callback returns.
		345
		346	This means that the callback would be called roughly after C<$after>
		347	seconds, and then every C<$repeat> seconds. The timer does his best not
		348	to drift, but it will not invoke the timer more often then once per event
		349	loop iteration, and might drift in other cases. If that isn't acceptable,
		350	look at EV::periodic, which can provide long-term stable timers.
		351
		352	The timer is based on a monotonic clock, that is, if somebody is sitting
		353	in front of the machine while the timer is running and changes the system
		354	clock, the timer will nevertheless run (roughly) the same time.
		355
		356	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		357
190	=item $w->timeout ($after, $repeat)	358	=item $w->set ($after, $repeat)
191		359
192	Resets the timeout (see C<EV::timer> for details).	360	Reconfigures the watcher, see the constructor above for details. Can be called at
		361	any time.
193		362
		363	=item $w->again
		364
		365	Similar to the C<start> method, but has special semantics for repeating timers:
		366
		367	If the timer is active and non-repeating, it will be stopped.
		368
		369	If the timer is active and repeating, reset the timeout to occur
		370	C<$repeat> seconds after now.
		371
		372	If the timer is inactive and repeating, start it using the repeat value.
		373
		374	Otherwise do nothing.
		375
		376	This behaviour is useful when you have a timeout for some IO
		377	operation. You create a timer object with the same value for C<$after> and
		378	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		379	on the timeout.
		380
		381	=back
		382
		383
		384	=head3 PERIODIC WATCHERS - to cron or not to cron?
		385
		386	=over 4
		387
		388	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		389
		390	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		391
		392	Similar to EV::timer, but is not based on relative timeouts but on
		393	absolute times. Apart from creating "simple" timers that trigger "at" the
		394	specified time, it can also be used for non-drifting absolute timers and
		395	more complex, cron-like, setups that are not adversely affected by time
		396	jumps (i.e. when the system clock is changed by explicit date -s or other
		397	means such as ntpd). It is also the most complex watcher type in EV.
		398
		399	It has three distinct "modes":
		400
		401	=over 4
		402
		403	=item * absolute timer ($interval = $reschedule_cb = 0)
		404
		405	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		406	will not adjust when a time jump occurs, that is, if it is to be run
		407	at January 1st 2011 then it will run when the system time reaches or
		408	surpasses this time.
		409
		410	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		411
		412	In this mode the watcher will always be scheduled to time out at the
		413	next C<$at + N * $interval> time (for some integer N) and then repeat,
		414	regardless of any time jumps.
		415
		416	This can be used to create timers that do not drift with respect to system
		417	time:
		418
		419	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		420
		421	That doesn't mean there will always be 3600 seconds in between triggers,
		422	but only that the the clalback will be called when the system time shows a
		423	full hour (UTC).
		424
		425	Another way to think about it (for the mathematically inclined) is that
		426	EV::periodic will try to run the callback in this mode at the next
		427	possible time where C<$time = $at (mod $interval)>, regardless of any time
		428	jumps.
		429
		430	=item * manual reschedule mode ($reschedule_cb = coderef)
		431
		432	In this mode $interval and $at are both being ignored. Instead, each
		433	time the periodic watcher gets scheduled, the reschedule callback
		434	($reschedule_cb) will be called with the watcher as first, and the current
		435	time as second argument.
		436
		437	I<This callback MUST NOT stop or destroy this or any other periodic
		438	watcher, ever>. If you need to stop it, return 1e30 and stop it
		439	afterwards.
		440
		441	It must return the next time to trigger, based on the passed time value
		442	(that is, the lowest time value larger than to the second argument). It
		443	will usually be called just before the callback will be triggered, but
		444	might be called at other times, too.
		445
		446	This can be used to create very complex timers, such as a timer that
		447	triggers on each midnight, local time (actually 24 hours after the last
		448	midnight, to keep the example simple. If you know a way to do it correctly
		449	in about the same space (without requiring elaborate modules), drop me a
		450	note :):
		451
		452	my $daily = EV::periodic 0, 0, sub {
		453	my ($w, $now) = @_;
		454
		455	use Time::Local ();
		456	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		457	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		458	}, sub {
		459	print "it's midnight or likely shortly after, now\n";
		460	};
		461
		462	=back
		463
		464	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		465
		466	=item $w->set ($at, $interval, $reschedule_cb)
		467
		468	Reconfigures the watcher, see the constructor above for details. Can be called at
		469	any time.
		470
		471	=item $w->again
		472
		473	Simply stops and starts the watcher again.
		474
		475	=back
		476
		477
		478	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		479
		480	=over 4
		481
		482	=item $w = EV::signal $signal, $callback
		483
		484	=item $w = EV::signal_ns $signal, $callback
		485
		486	Call the callback when $signal is received (the signal can be specified by
		487	number or by name, just as with C<kill> or C<%SIG>).
		488
		489	EV will grab the signal for the process (the kernel only allows one
		490	component to receive a signal at a time) when you start a signal watcher,
		491	and removes it again when you stop it. Perl does the same when you
		492	add/remove callbacks to C<%SIG>, so watch out.
		493
		494	You can have as many signal watchers per signal as you want.
		495
		496	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		497
		498	=item $w->set ($signal)
		499
		500	Reconfigures the watcher, see the constructor above for details. Can be
		501	called at any time.
		502
		503	=item $current_signum = $w->signal
		504
		505	=item $old_signum = $w->signal ($new_signal)
		506
		507	Returns the previously set signal (always as a number not name) and
		508	optionally set a new one.
		509
		510	=back
		511
		512
		513	=head3 CHILD WATCHERS - watch out for process status changes
		514
		515	=over 4
		516
		517	=item $w = EV::child $pid, $callback
		518
		519	=item $w = EV::child_ns $pid, $callback
		520
		521	Call the callback when a status change for pid C<$pid> (or any pid if
		522	C<$pid> is 0) has been received. More precisely: when the process receives
		523	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		524	changed/zombie children and call the callback.
		525
		526	It is valid (and fully supported) to install a child watcher after a child
		527	has exited but before the event loop has started its next iteration (for
		528	example, first you C<fork>, then the new child process might exit, and
		529	only then do you install a child watcher in the parent for the new pid).
		530
		531	You can access both exit (or tracing) status and pid by using the
		532	C<rstatus> and C<rpid> methods on the watcher object.
		533
		534	You can have as many pid watchers per pid as you want, they will all be
		535	called.
		536
		537	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		538
		539	=item $w->set ($pid)
		540
		541	Reconfigures the watcher, see the constructor above for details. Can be called at
		542	any time.
		543
		544	=item $current_pid = $w->pid
		545
		546	=item $old_pid = $w->pid ($new_pid)
		547
		548	Returns the previously set process id and optionally set a new one.
		549
		550	=item $exit_status = $w->rstatus
		551
		552	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		553	in perlfunc).
		554
		555	=item $pid = $w->rpid
		556
		557	Return the pid of the awaited child (useful when you have installed a
		558	watcher for all pids).
		559
		560	=back
		561
		562
		563	=head3 STAT WATCHERS - did the file attributes just change?
		564
		565	=over 4
		566
		567	=item $w = EV::stat $path, $interval, $callback
		568
		569	=item $w = EV::stat_ns $path, $interval, $callback
		570
		571	Call the callback when a file status change has been detected on
		572	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		573	to "path does not exist" is a status change like any other.
		574
		575	The C<$interval> is a recommended polling interval for systems where
		576	OS-supported change notifications don't exist or are not supported. If
		577	you use C<0> then an unspecified default is used (which is highly
		578	recommended!), which is to be expected to be around five seconds usually.
		579
		580	This watcher type is not meant for massive numbers of stat watchers,
		581	as even with OS-supported change notifications, this can be
		582	resource-intensive.
		583
		584	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		585
		586	=item ... = $w->stat
		587
		588	This call is very similar to the perl C<stat> built-in: It stats (using
		589	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		590	well as EV's idea of the current stat values) to the values found.
		591
		592	In scalar context, a boolean is return indicating success or failure of
		593	the stat. In list context, the same 13-value list as with stat is returned
		594	(except that the blksize and blocks fields are not reliable).
		595
		596	In the case of an error, errno is set to C<ENOENT> (regardless of the
		597	actual error value) and the C<nlink> value is forced to zero (if the stat
		598	was successful then nlink is guaranteed to be non-zero).
		599
		600	See also the next two entries for more info.
		601
		602	=item ... = $w->attr
		603
		604	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		605	the values most recently detected by EV. See the next entry for more info.
		606
		607	=item ... = $w->prev
		608
		609	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		610	the previous set of values, before the change.
		611
		612	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		613	to the values found I<before> a change was detected, while C<< $w->attr >>
		614	returns the values found leading to the change detection. The difference (if any)
		615	between C<prev> and C<attr> is what triggered the callback.
		616
		617	If you did something to the filesystem object and do not want to trigger
		618	yet another change, you can call C<stat> to update EV's idea of what the
		619	current attributes are.
		620
194	=item $w->timeout_abs ($at, $interval)	621	=item $w->set ($path, $interval)
195		622
196	Resets the timeout (see C<EV::timer_abs> for details).	623	Reconfigures the watcher, see the constructor above for details. Can be
		624	called at any time.
197		625
198	=item $w->priority_set ($priority)	626	=item $current_path = $w->path
199		627
200	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	628	=item $old_path = $w->path ($new_path)
201		629
202	=back	630	Returns the previously set path and optionally set a new one.
203		631
204	=head1 BUGS	632	=item $current_interval = $w->interval
205		633
206	Lots. Libevent itself isn't well tested and rather buggy, and this module	634	=item $old_interval = $w->interval ($new_interval)
207	is quite new at the moment.	635
		636	Returns the previously set interval and optionally set a new one. Can be
		637	used to query the actual interval used.
		638
		639	=back
		640
		641
		642	=head3 IDLE WATCHERS - when you've got nothing better to do...
		643
		644	=over 4
		645
		646	=item $w = EV::idle $callback
		647
		648	=item $w = EV::idle_ns $callback
		649
		650	Call the callback when there are no pending io, timer/periodic, signal or
		651	child events, i.e. when the process is idle.
		652
		653	The process will not block as long as any idle watchers are active, and
		654	they will be called repeatedly until stopped.
		655
		656	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		657
		658	=back
		659
		660
		661	=head3 PREPARE WATCHERS - customise your event loop!
		662
		663	=over 4
		664
		665	=item $w = EV::prepare $callback
		666
		667	=item $w = EV::prepare_ns $callback
		668
		669	Call the callback just before the process would block. You can still
		670	create/modify any watchers at this point.
		671
		672	See the EV::check watcher, below, for explanations and an example.
		673
		674	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		675
		676	=back
		677
		678
		679	=head3 CHECK WATCHERS - customise your event loop even more!
		680
		681	=over 4
		682
		683	=item $w = EV::check $callback
		684
		685	=item $w = EV::check_ns $callback
		686
		687	Call the callback just after the process wakes up again (after it has
		688	gathered events), but before any other callbacks have been invoked.
		689
		690	This is used to integrate other event-based software into the EV
		691	mainloop: You register a prepare callback and in there, you create io and
		692	timer watchers as required by the other software. Here is a real-world
		693	example of integrating Net::SNMP (with some details left out):
		694
		695	our @snmp_watcher;
		696
		697	our $snmp_prepare = EV::prepare sub {
		698	# do nothing unless active
		699	$dispatcher->{_event_queue_h}
		700	or return;
		701
		702	# make the dispatcher handle any outstanding stuff
		703	... not shown
		704
		705	# create an IO watcher for each and every socket
		706	@snmp_watcher = (
		707	(map { EV::io $_, EV::READ, sub { } }
		708	keys %{ $dispatcher->{_descriptors} }),
		709
		710	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		711	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		712	0, sub { },
		713	);
		714	};
		715
		716	The callbacks are irrelevant (and are not even being called), the
		717	only purpose of those watchers is to wake up the process as soon as
		718	one of those events occurs (socket readable, or timer timed out). The
		719	corresponding EV::check watcher will then clean up:
		720
		721	our $snmp_check = EV::check sub {
		722	# destroy all watchers
		723	@snmp_watcher = ();
		724
		725	# make the dispatcher handle any new stuff
		726	... not shown
		727	};
		728
		729	The callbacks of the created watchers will not be called as the watchers
		730	are destroyed before this cna happen (remember EV::check gets called
		731	first).
		732
		733	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		734
		735	=back
		736
		737
		738	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		739
		740	Fork watchers are called when a C<fork ()> was detected. The invocation
		741	is done before the event loop blocks next and before C<check> watchers
		742	are being called, and only in the child after the fork.
		743
		744	=over 4
		745
		746	=item $w = EV::fork $callback
		747
		748	=item $w = EV::fork_ns $callback
		749
		750	Call the callback before the event loop is resumed in the child process
		751	after a fork.
		752
		753	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		754
		755	=back
		756
		757
		758	=head1 PERL SIGNALS
		759
		760	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		761	with EV is as the same as any other C library: Perl-signals will only be
		762	handled when Perl runs, which means your signal handler might be invoked
		763	only the next time an event callback is invoked.
		764
		765	The solution is to use EV signal watchers (see C<EV::signal>), which will
		766	ensure proper operations with regards to other event watchers.
		767
		768	If you cannot do this for whatever reason, you can also force a watcher
		769	to be called on every event loop iteration by installing a C<EV::check>
		770	watcher:
		771
		772	my $async_check = EV::check sub { };
		773
		774	This ensures that perl shortly gets into control for a short time, and
		775	also ensures slower overall operation.
		776
		777	=head1 THREADS
		778
		779	Threads are not supported by this module in any way. Perl pseudo-threads
		780	is evil stuff and must die. As soon as Perl gains real threads I will work
		781	on thread support for it.
		782
		783	=head1 FORK
		784
		785	Most of the "improved" event delivering mechanisms of modern operating
		786	systems have quite a few problems with fork(2) (to put it bluntly: it is
		787	not supported and usually destructive). Libev makes it possible to work
		788	around this by having a function that recreates the kernel state after
		789	fork in the child.
		790
		791	On non-win32 platforms, this module requires the pthread_atfork
		792	functionality to do this automatically for you. This function is quite
		793	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		794	negligible, because everything the function currently does is set a flag
		795	that is checked only when the event loop gets used the next time, so when
		796	you do fork but not use EV, the overhead is minimal.
		797
		798	On win32, there is no notion of fork so all this doesn't apply, of course.
208		799
209	=cut	800	=cut
210		801
211	our $NPRI = 4;	802	our $DIED = sub {
212	our $BASE = init;	803	warn "EV: error in callback (ignoring): $@";
213	priority_init $NPRI;	804	};
214		805
215	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];	806	default_loop
		807	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
216		808
217	1;	809	1;
218		810
219	=head1 SEE ALSO	811	=head1 SEE ALSO
220		812
221	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	813	L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
		814	event loop), L<Coro::EV> (efficient coroutines with EV).
222		815
223	=head1 AUTHOR	816	=head1 AUTHOR
224		817
225	Marc Lehmann <schmorp@schmorp.de>	818	Marc Lehmann <schmorp@schmorp.de>
226	http://home.schmorp.de/	819	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs. Revision 1.61 by root, Thu Dec 6 03:13:07 2007 UTC

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Revision 1.4 by root, Fri Oct 26 19:11:35 2007 UTC vs.
Revision 1.61 by root, Thu Dec 6 03:13:07 2007 UTC