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

Comparing EV/EV.pm (file contents):
Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs.
Revision 1.56 by root, Tue Nov 27 10:59:10 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 "nothing 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>.
51	default, see BUGS, below, if you need to enable it.
52		64
53	=cut	65	=cut
54		66
55	package EV;	67	package EV;
56		68
57	use strict;	69	use strict;
58		70
59	BEGIN {	71	BEGIN {
60	our $VERSION = '0.02';	72	our $VERSION = '1.4';
61	use XSLoader;	73	use XSLoader;
62	XSLoader::load "EV", $VERSION;	74	XSLoader::load "EV", $VERSION;
63	}	75	}
64		76
		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";
		89
65	=head1 BASIC INTERFACE	90	=head1 BASIC INTERFACE
66		91
67	=over 4	92	=over 4
68
69	=item $EV::NPRI
70
71	How many priority levels are available.
72		93
73	=item $EV::DIED	94	=item $EV::DIED
74		95
75	Must contain a reference to a function that is called when a callback	96	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	97	throws an exception (with $@ containing thr error). The default prints an
77	informative message and continues.	98	informative message and continues.
78		99
79	If this callback throws an exception it will be silently ignored.	100	If this callback throws an exception it will be silently ignored.
80		101
		102	=item $time = EV::time
		103
		104	Returns the current time in (fractional) seconds since the epoch.
		105
81	=item $time = EV::now	106	=item $time = EV::now
82		107
83	Returns the time in (fractional) seconds since the epoch.	108	Returns the time the last event loop iteration has been started. This
84		109	is the time that (relative) timers are based on, and refering to it is
85	=item $version = EV::version	110	usually faster then calling EV::time.
86		111
87	=item $method = EV::method	112	=item $method = EV::method
88		113
89	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).
90		116
91	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	117	=item EV::loop [$flags]
92		118
93	=item EV::loopexit $after	119	Begin checking for events and calling callbacks. It returns when a
		120	callback calls EV::unloop.
94		121
95	Exit any active loop or dispatch after C<$after> seconds or immediately if	122	The $flags argument can be one of the following:
96	C<$after> is missing or zero.
97		123
98	=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)
99		127
100	Same as C<EV::loop 0>.	128	=item EV::unloop [$how]
101		129
102	=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.
103		132
104	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.
105		135
		136	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		137
		138	This function rolls together an I/O and a timer watcher for a single
		139	one-shot event without the need for managing a watcher object.
		140
		141	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		142	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		143	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		144	you do not want to wait for some I/O event, specify C<undef> for
		145	C<$fh_or_undef> and C<0> for C<$events>).
		146
		147	If timeout is C<undef> or negative, then there will be no
		148	timeout. Otherwise a EV::timer with this value will be started.
		149
		150	When an error occurs or either the timeout or I/O watcher triggers, then
		151	the callback will be called with the received event set (in general
		152	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		153	C<EV::WRITE> and C<EV::TIMEOUT>).
		154
		155	EV::once doesn't return anything: the watchers stay active till either
		156	of them triggers, then they will be stopped and freed, and the callback
		157	invoked.
		158
		159	=back
		160
		161	=head2 WATCHER OBJECTS
		162
		163	A watcher is an object that gets created to record your interest in some
		164	event. For instance, if you want to wait for STDIN to become readable, you
		165	would create an EV::io watcher for that:
		166
		167	my $watcher = EV::io *STDIN, EV::READ, sub {
		168	my ($watcher, $revents) = @_;
		169	warn "yeah, STDIN should not be readable without blocking!\n"
		170	};
		171
		172	All watchers can be active (waiting for events) or inactive (paused). Only
		173	active watchers will have their callbacks invoked. All callbacks will be
		174	called with at least two arguments: the watcher and a bitmask of received
		175	events.
		176
		177	Each watcher type has its associated bit in revents, so you can use the
		178	same callback for multiple watchers. The event mask is named after the
		179	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		180	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		181	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		182	uses EV::TIMEOUT).
		183
		184	In the rare case where one wants to create a watcher but not start it at
		185	the same time, each constructor has a variant with a trailing C<_ns> in
		186	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		187
		188	Please note that a watcher will automatically be stopped when the watcher
		189	object is destroyed, so you I<need> to keep the watcher objects returned by
		190	the constructors.
		191
		192	Also, all methods changing some aspect of a watcher (->set, ->priority,
		193	->fh and so on) automatically stop and start it again if it is active,
		194	which means pending events get lost.
		195
		196	=head2 COMMON WATCHER METHODS
		197
		198	This section lists methods common to all watchers.
		199
		200	=over 4
		201
		202	=item $w->start
		203
		204	Starts a watcher if it isn't active already. Does nothing to an already
		205	active watcher. By default, all watchers start out in the active state
		206	(see the description of the C<_ns> variants if you need stopped watchers).
		207
		208	=item $w->stop
		209
		210	Stop a watcher if it is active. Also clear any pending events (events that
		211	have been received but that didn't yet result in a callback invocation),
		212	regardless of wether the watcher was active or not.
		213
		214	=item $bool = $w->is_active
		215
		216	Returns true if the watcher is active, false otherwise.
		217
		218	=item $current_data = $w->data
		219
		220	=item $old_data = $w->data ($new_data)
		221
		222	Queries a freely usable data scalar on the watcher and optionally changes
		223	it. This is a way to associate custom data with a watcher:
		224
		225	my $w = EV::timer 60, 0, sub {
		226	warn $_[0]->data;
		227	};
		228	$w->data ("print me!");
		229
		230	=item $current_cb = $w->cb
		231
		232	=item $old_cb = $w->cb ($new_cb)
		233
		234	Queries the callback on the watcher and optionally changes it. You can do
		235	this at any time without the watcher restarting.
		236
		237	=item $current_priority = $w->priority
		238
		239	=item $old_priority = $w->priority ($new_priority)
		240
		241	Queries the priority on the watcher and optionally changes it. Pending
		242	watchers with higher priority will be invoked first. The valid range of
		243	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		244	-2). If the priority is outside this range it will automatically be
		245	normalised to the nearest valid priority.
		246
		247	The default priority of any newly-created watcher is 0.
		248
		249	Note that the priority semantics have not yet been fleshed out and are
		250	subject to almost certain change.
		251
		252	=item $w->trigger ($revents)
		253
		254	Call the callback now with the given event mask.
		255
		256	=item $previous_state = $w->keepalive ($bool)
		257
		258	Normally, C<EV::loop> will return when there are no active watchers
		259	(which is a "deadlock" because no progress can be made anymore). This is
		260	convinient because it allows you to start your watchers (and your jobs),
		261	call C<EV::loop> once and when it returns you know that all your jobs are
		262	finished (or they forgot to register some watchers for their task :).
		263
		264	Sometimes, however, this gets in your way, for example when you the module
		265	that calls C<EV::loop> (usually the main program) is not the same module
		266	as a long-living watcher (for example a DNS client module written by
		267	somebody else even). Then you might want any outstanding requests to be
		268	handled, but you would not want to keep C<EV::loop> from returning just
		269	because you happen to have this long-running UDP port watcher.
		270
		271	In this case you can clear the keepalive status, which means that even
		272	though your watcher is active, it won't keep C<EV::loop> from returning.
		273
		274	The initial value for keepalive is true (enabled), and you cna change it
		275	any time.
		276
		277	Example: Register an IO watcher for some UDP socket but do not keep the
		278	event loop from running just because of that watcher.
		279
		280	my $udp_socket = ...
		281	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		282	$udp_watcher->keepalive (0);
		283
		284	=back
		285
		286
		287	=head2 WATCHER TYPES
		288
		289	Each of the following subsections describes a single watcher type.
		290
		291	=head3 IO WATCHERS - is this file descriptor readable or writable?
		292
		293	=over 4
		294
106	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	295	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
107		296
108	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	297	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
109		298
110	As long as the returned watcher object is alive, call the C<$callback>	299	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	300	when at least one of events specified in C<$eventmask> occurs.
112	is disabled.
113		301
114	You can 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:	302	The $eventmask can be one or more of these constants ORed together:
123		303
124	EV::READ wait until read() wouldn't block anymore	304	EV::READ wait until read() wouldn't block anymore
125	EV::WRITE wait until write() wouldn't block anymore	305	EV::WRITE wait until write() wouldn't block anymore
126	EV::PERSIST stay active after a (non-timeout) event occured
127		306
128	The C<io_ns> variant doesn't add/start the newly created watcher.	307	The C<io_ns> variant doesn't start (activate) the newly created watcher.
129		308
130	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	309	=item $w->set ($fileno_or_fh, $eventmask)
131		310
132	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	311	Reconfigures the watcher, see the constructor above for details. Can be
		312	called at any time.
133		313
134	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	314	=item $current_fh = $w->fh
135	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
136	and will automatically be cleared. The watcher will be restarted after each event.
137		315
138	If the timeout is zero or undef, no timeout will be set, and a normal	316	=item $old_fh = $w->fh ($new_fh)
139	watcher (with the persist flag set!) will be created.
140		317
141	This has the effect of timing out after the specified period of inactivity	318	Returns the previously set filehandle and optionally set a new one.
142	has happened.
143		319
144	Due to the design of libevent, this is also relatively inefficient, having	320	=item $current_eventmask = $w->events
145	one or two io watchers and a separate timeout watcher that you reset on
146	activity (by calling its C<start> method) is usually more efficient.
147		321
		322	=item $old_eventmask = $w->events ($new_eventmask)
		323
		324	Returns the previously set event mask and optionally set a new one.
		325
		326	=back
		327
		328
		329	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		330
		331	=over 4
		332
148	=item my $w = EV::timer $after, $repeat, $callback	333	=item $w = EV::timer $after, $repeat, $callback
149		334
150	=item my $w = EV::timer_ns $after, $repeat, $callback	335	=item $w = EV::timer_ns $after, $repeat, $callback
151		336
152	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	337	Calls the callback after C<$after> seconds (which may be fractional). If
153	timer will be restarted after the callback returns. This means that the	338	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
154	callback would be called roughly every C<$after> seconds, prolonged by the	339	value as $after) after the callback returns.
155	time the callback takes.
156		340
		341	This means that the callback would be called roughly after C<$after>
		342	seconds, and then every C<$repeat> seconds. The timer does his best not
		343	to drift, but it will not invoke the timer more often then once per event
		344	loop iteration, and might drift in other cases. If that isn't acceptable,
		345	look at EV::periodic, which can provide long-term stable timers.
		346
		347	The timer is based on a monotonic clock, that is, if somebody is sitting
		348	in front of the machine while the timer is running and changes the system
		349	clock, the timer will nevertheless run (roughly) the same time.
		350
157	The C<timer_ns> variant doesn't add/start the newly created watcher.	351	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
158		352
159	=item my $w = EV::timer_abs $at, $interval, $callback	353	=item $w->set ($after, $repeat)
160		354
161	=item my $w = EV::timer_abs_ns $at, $interval, $callback	355	Reconfigures the watcher, see the constructor above for details. Can be called at
		356	any time.
162		357
163	Similar to EV::timer, but the time is given as an absolute point in time	358	=item $w->again
164	(C<$at>), plus an optional C<$interval>.
165		359
166	If the C<$interval> is zero, then the callback will be called at the time	360	Similar to the C<start> method, but has special semantics for repeating timers:
167	C<$at> if that is in the future, or as soon as possible if its in the
168	past. It will not automatically repeat.
169		361
170	If the C<$interval> is nonzero, then the watcher will always be scheduled	362	If the timer is active and non-repeating, it will be stopped.
171	to time out at the next C<$at + integer * $interval> time.
172		363
173	This can be used to schedule a callback to run at very regular intervals,	364	If the timer is active and repeating, reset the timeout to occur
174	as long as the processing time is less then the interval (otherwise	365	C<$repeat> seconds after now.
175	obviously events will be skipped).	366
		367	If the timer is inactive and repeating, start it using the repeat value.
		368
		369	Otherwise do nothing.
		370
		371	This behaviour is useful when you have a timeout for some IO
		372	operation. You create a timer object with the same value for C<$after> and
		373	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		374	on the timeout.
		375
		376	=back
		377
		378
		379	=head3 PERIODIC WATCHERS - to cron or not to cron?
		380
		381	=over 4
		382
		383	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		384
		385	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		386
		387	Similar to EV::timer, but is not based on relative timeouts but on
		388	absolute times. Apart from creating "simple" timers that trigger "at" the
		389	specified time, it can also be used for non-drifting absolute timers and
		390	more complex, cron-like, setups that are not adversely affected by time
		391	jumps (i.e. when the system clock is changed by explicit date -s or other
		392	means such as ntpd). It is also the most complex watcher type in EV.
		393
		394	It has three distinct "modes":
		395
		396	=over 4
		397
		398	=item * absolute timer ($interval = $reschedule_cb = 0)
		399
		400	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		401	will not adjust when a time jump occurs, that is, if it is to be run
		402	at January 1st 2011 then it will run when the system time reaches or
		403	surpasses this time.
		404
		405	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		406
		407	In this mode the watcher will always be scheduled to time out at the
		408	next C<$at + N * $interval> time (for some integer N) and then repeat,
		409	regardless of any time jumps.
		410
		411	This can be used to create timers that do not drift with respect to system
		412	time:
		413
		414	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		415
		416	That doesn't mean there will always be 3600 seconds in between triggers,
		417	but only that the the clalback will be called when the system time shows a
		418	full hour (UTC).
176		419
177	Another way to think about it (for the mathematically inclined) is that	420	Another way to think about it (for the mathematically inclined) is that
178	C<timer_abs> will try to tun the callback at the next possible time where	421	EV::periodic will try to run the callback in this mode at the next
179	C<$time = $at (mod $interval)>, regardless of any time jumps.	422	possible time where C<$time = $at (mod $interval)>, regardless of any time
		423	jumps.
180		424
		425	=item * manual reschedule mode ($reschedule_cb = coderef)
		426
		427	In this mode $interval and $at are both being ignored. Instead, each
		428	time the periodic watcher gets scheduled, the reschedule callback
		429	($reschedule_cb) will be called with the watcher as first, and the current
		430	time as second argument.
		431
		432	I<This callback MUST NOT stop or destroy this or any other periodic
		433	watcher, ever>. If you need to stop it, return 1e30 and stop it
		434	afterwards.
		435
		436	It must return the next time to trigger, based on the passed time value
		437	(that is, the lowest time value larger than to the second argument). It
		438	will usually be called just before the callback will be triggered, but
		439	might be called at other times, too.
		440
		441	This can be used to create very complex timers, such as a timer that
		442	triggers on each midnight, local time (actually 24 hours after the last
		443	midnight, to keep the example simple. If you know a way to do it correctly
		444	in about the same space (without requiring elaborate modules), drop me a
		445	note :):
		446
		447	my $daily = EV::periodic 0, 0, sub {
		448	my ($w, $now) = @_;
		449
		450	use Time::Local ();
		451	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		452	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		453	}, sub {
		454	print "it's midnight or likely shortly after, now\n";
		455	};
		456
		457	=back
		458
181	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	459	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
182		460
		461	=item $w->set ($at, $interval, $reschedule_cb)
		462
		463	Reconfigures the watcher, see the constructor above for details. Can be called at
		464	any time.
		465
		466	=item $w->again
		467
		468	Simply stops and starts the watcher again.
		469
		470	=back
		471
		472
		473	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		474
		475	=over 4
		476
183	=item my $w = EV::signal $signum, $callback	477	=item $w = EV::signal $signal, $callback
184		478
185	=item my $w = EV::signal_ns $signum, $callback	479	=item $w = EV::signal_ns $signal, $callback
186		480
187	Call the callback when signal $signum is received.	481	Call the callback when $signal is received (the signal can be specified by
		482	number or by name, just as with C<kill> or C<%SIG>).
188		483
		484	EV will grab the signal for the process (the kernel only allows one
		485	component to receive a signal at a time) when you start a signal watcher,
		486	and removes it again when you stop it. Perl does the same when you
		487	add/remove callbacks to C<%SIG>, so watch out.
		488
		489	You can have as many signal watchers per signal as you want.
		490
189	The C<signal_ns> variant doesn't add/start the newly created watcher.	491	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
190		492
191	=back	493	=item $w->set ($signal)
192		494
193	=head1 THE EV::Event CLASS	495	Reconfigures the watcher, see the constructor above for details. Can be
		496	called at any time.
194		497
195	All EV functions creating an event watcher (designated by C<my $w =>
196	above) support the following methods on the returned watcher object:
197
198	=over 4
199
200	=item $w->add ($timeout)
201
202	Stops and (re-)starts the event watcher, setting the optional timeout to
203	the given value, or clearing the timeout if none is given.
204
205	=item $w->start
206
207	Stops and (re-)starts the event watcher without touching the timeout.
208
209	=item $w->del
210
211	=item $w->stop
212
213	Stop the event watcher if it was started.
214
215	=item $current_callback = $w->cb
216
217	=item $old_callback = $w->cb ($new_callback)
218
219	Return the previously set callback and optionally set a new one.
220
221	=item $current_fh = $w->fh
222
223	=item $old_fh = $w->fh ($new_fh)
224
225	Returns the previously set filehandle and optionally set a new one (also
226	clears the EV::SIGNAL flag when setting a filehandle).
227
228	=item $current_signal = $w->signal	498	=item $current_signum = $w->signal
229		499
230	=item $old_signal = $w->signal ($new_signal)	500	=item $old_signum = $w->signal ($new_signal)
231		501
		502	Returns the previously set signal (always as a number not name) and
		503	optionally set a new one.
		504
		505	=back
		506
		507
		508	=head3 CHILD WATCHERS - watch out for process status changes
		509
		510	=over 4
		511
		512	=item $w = EV::child $pid, $callback
		513
		514	=item $w = EV::child_ns $pid, $callback
		515
		516	Call the callback when a status change for pid C<$pid> (or any pid if
		517	C<$pid> is 0) has been received. More precisely: when the process receives
		518	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		519	changed/zombie children and call the callback.
		520
		521	It is valid (and fully supported) to install a child watcher after a child
		522	has exited but before the event loop has started its next iteration (for
		523	example, first you C<fork>, then the new child process might exit, and
		524	only then do you install a child watcher in the parent for the new pid).
		525
		526	You can access both exit (or tracing) status and pid by using the
		527	C<rstatus> and C<rpid> methods on the watcher object.
		528
		529	You can have as many pid watchers per pid as you want, they will all be
		530	called.
		531
		532	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		533
		534	=item $w->set ($pid)
		535
		536	Reconfigures the watcher, see the constructor above for details. Can be called at
		537	any time.
		538
		539	=item $current_pid = $w->pid
		540
		541	=item $old_pid = $w->pid ($new_pid)
		542
232	Returns the previously set signal number and optionally set a new one (also sets	543	Returns the previously set process id and optionally set a new one.
233	the EV::SIGNAL flag when setting a signal).
234		544
235	=item $current_eventmask = $w->events	545	=item $exit_status = $w->rstatus
236		546
237	=item $old_eventmask = $w->events ($new_eventmask)	547	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		548	in perlfunc).
238		549
		550	=item $pid = $w->rpid
		551
		552	Return the pid of the awaited child (useful when you have installed a
		553	watcher for all pids).
		554
		555	=back
		556
		557
		558	=head3 STAT WATCHERS - did the file attributes just change?
		559
		560	=over 4
		561
		562	=item $w = EV::stat $path, $interval, $callback
		563
		564	=item $w = EV::stat_ns $path, $interval, $callback
		565
		566	Call the callback when a file status change has been detected on
		567	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		568	to "path does not exist" is a status change like any other.
		569
		570	The C<$interval> is a recommended polling interval for systems where
		571	OS-supported change notifications don't exist or are not supported. If
		572	you use C<0> then an unspecified default is used (which is highly
		573	recommended!), which is to be expected to be around five seconds usually.
		574
		575	This watcher type is not meant for massive numbers of stat watchers,
		576	as even with OS-supported change notifications, this can be
		577	resource-intensive.
		578
		579	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		580
		581	=item $w->set ($path, $interval)
		582
		583	Reconfigures the watcher, see the constructor above for details. Can be
		584	called at any time.
		585
		586	=item $current_path = $w->path
		587
		588	=item $old_path = $w->path ($new_path)
		589
239	Returns the previously set event mask and optionally set a new one.	590	Returns the previously set path and optionally set a new one.
240		591
241	=item $w->timeout ($after, $repeat)	592	=item $current_interval = $w->interval
242		593
243	Resets the timeout (see C<EV::timer> for details).	594	=item $old_interval = $w->interval ($new_interval)
244		595
245	=item $w->timeout_abs ($at, $interval)	596	Returns the previously set interval and optionally set a new one. Can be
		597	used to query the actual interval used.
246		598
247	Resets the timeout (see C<EV::timer_abs> for details).
248
249	=item $w->priority_set ($priority)
250
251	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
252
253	=back	599	=back
254		600
255	=head1 BUGS
256		601
257	Lots. Libevent itself isn't well tested and rather buggy, and this module	602	=head3 IDLE WATCHERS - when you've got nothing better to do...
258	is quite new at the moment.
259		603
260	Please note that the epoll method is not, in general, reliable in programs	604	=over 4
261	that use fork (even if no libveent calls are being made in the forked
262	process). If your program behaves erratically, try setting the environment
263	variable C<EVENT_NOEPOLL> first when running the program.
264		605
265	In general, if you fork, then you can only use the EV module in one of the	606	=item $w = EV::idle $callback
266	children.	607
		608	=item $w = EV::idle_ns $callback
		609
		610	Call the callback when there are no pending io, timer/periodic, signal or
		611	child events, i.e. when the process is idle.
		612
		613	The process will not block as long as any idle watchers are active, and
		614	they will be called repeatedly until stopped.
		615
		616	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		617
		618	=back
		619
		620
		621	=head3 PREPARE WATCHERS - customise your event loop!
		622
		623	=over 4
		624
		625	=item $w = EV::prepare $callback
		626
		627	=item $w = EV::prepare_ns $callback
		628
		629	Call the callback just before the process would block. You can still
		630	create/modify any watchers at this point.
		631
		632	See the EV::check watcher, below, for explanations and an example.
		633
		634	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		635
		636	=back
		637
		638
		639	=head3 CHECK WATCHERS - customise your event loop even more!
		640
		641	=over 4
		642
		643	=item $w = EV::check $callback
		644
		645	=item $w = EV::check_ns $callback
		646
		647	Call the callback just after the process wakes up again (after it has
		648	gathered events), but before any other callbacks have been invoked.
		649
		650	This is used to integrate other event-based software into the EV
		651	mainloop: You register a prepare callback and in there, you create io and
		652	timer watchers as required by the other software. Here is a real-world
		653	example of integrating Net::SNMP (with some details left out):
		654
		655	our @snmp_watcher;
		656
		657	our $snmp_prepare = EV::prepare sub {
		658	# do nothing unless active
		659	$dispatcher->{_event_queue_h}
		660	or return;
		661
		662	# make the dispatcher handle any outstanding stuff
		663	... not shown
		664
		665	# create an IO watcher for each and every socket
		666	@snmp_watcher = (
		667	(map { EV::io $_, EV::READ, sub { } }
		668	keys %{ $dispatcher->{_descriptors} }),
		669
		670	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		671	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		672	0, sub { },
		673	);
		674	};
		675
		676	The callbacks are irrelevant (and are not even being called), the
		677	only purpose of those watchers is to wake up the process as soon as
		678	one of those events occurs (socket readable, or timer timed out). The
		679	corresponding EV::check watcher will then clean up:
		680
		681	our $snmp_check = EV::check sub {
		682	# destroy all watchers
		683	@snmp_watcher = ();
		684
		685	# make the dispatcher handle any new stuff
		686	... not shown
		687	};
		688
		689	The callbacks of the created watchers will not be called as the watchers
		690	are destroyed before this cna happen (remember EV::check gets called
		691	first).
		692
		693	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		694
		695	=back
		696
		697
		698	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		699
		700	Fork watchers are called when a C<fork ()> was detected. The invocation
		701	is done before the event loop blocks next and before C<check> watchers
		702	are being called, and only in the child after the fork.
		703
		704	=over 4
		705
		706	=item $w = EV::fork $callback
		707
		708	=item $w = EV::fork_ns $callback
		709
		710	Call the callback before the event loop is resumed in the child process
		711	after a fork.
		712
		713	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		714
		715	=back
		716
		717
		718	=head1 THREADS
		719
		720	Threads are not supported by this module in any way. Perl pseudo-threads
		721	is evil stuff and must die. As soon as Perl gains real threads I will work
		722	on thread support for it.
		723
		724	=head1 FORK
		725
		726	Most of the "improved" event delivering mechanisms of modern operating
		727	systems have quite a few problems with fork(2) (to put it bluntly: it is
		728	not supported and usually destructive). Libev makes it possible to work
		729	around this by having a function that recreates the kernel state after
		730	fork in the child.
		731
		732	On non-win32 platforms, this module requires the pthread_atfork
		733	functionality to do this automatically for you. This function is quite
		734	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		735	negligible, because everything the function currently does is set a flag
		736	that is checked only when the event loop gets used the next time, so when
		737	you do fork but not use EV, the overhead is minimal.
		738
		739	On win32, there is no notion of fork so all this doesn't apply, of course.
267		740
268	=cut	741	=cut
269		742
270	our $DIED = sub {	743	our $DIED = sub {
271	warn "EV: error in callback (ignoring): $@";	744	warn "EV: error in callback (ignoring): $@";
272	};	745	};
273		746
274	our $NPRI = 4;	747	default_loop
275	our $BASE = init;	748	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
276	priority_init $NPRI;
277
278	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
279		749
280	1;	750	1;
281		751
282	=head1 SEE ALSO	752	=head1 SEE ALSO
283		753
284	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	754	L<EV::DNS>.
285	L<EV::AnyEvent>.
286		755
287	=head1 AUTHOR	756	=head1 AUTHOR
288		757
289	Marc Lehmann <schmorp@schmorp.de>	758	Marc Lehmann <schmorp@schmorp.de>
290	http://home.schmorp.de/	759	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs. Revision 1.56 by root, Tue Nov 27 10:59:10 2007 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs.
Revision 1.56 by root, Tue Nov 27 10:59:10 2007 UTC