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

Comparing EV/EV.pm (file contents):
Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs.
Revision 1.72 by root, Thu Dec 20 07:12:57 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 = '2.0';
61	use XSLoader;	74	use XSLoader;
62	XSLoader::load "EV", $VERSION;	75	XSLoader::load "EV", $VERSION;
63	}	76	}
64		77
65	=head1 FUNCTIONAL INTERFACE	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";
66		90
67	=over 4	91	@EV::Loop::Default::ISA = "EV::Loop";
68		92
		93	=head1 BASIC INTERFACE
		94
		95	=over 4
		96
69	=item $EV::NPRI	97	=item $EV::DIED
70		98
71	How many priority levels are available.	99	Must contain a reference to a function that is called when a callback
		100	throws an exception (with $@ containing the error). The default prints an
		101	informative message and continues.
		102
		103	If this callback throws an exception it will be silently ignored.
		104
		105	=item $time = EV::time
		106
		107	Returns the current time in (fractional) seconds since the epoch.
72		108
73	=item $time = EV::now	109	=item $time = EV::now
74		110
75	Returns the time in (fractional) seconds since the epoch.	111	Returns the time the last event loop iteration has been started. This
76		112	is the time that (relative) timers are based on, and refering to it is
77	=item $version = EV::version	113	usually faster then calling EV::time.
78		114
79	=item $method = EV::method	115	=item $method = EV::method
80		116
81	Return version string and event polling method used.	117	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		118	or EV::METHOD_EPOLL).
82		119
83	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	120	=item EV::loop [$flags]
84		121
85	=item EV::loopexit $after	122	Begin checking for events and calling callbacks. It returns when a
		123	callback calls EV::unloop.
86		124
87	Exit any active loop or dispatch after C<$after> seconds or immediately if	125	The $flags argument can be one of the following:
88	C<$after> is missing or zero.
89		126
90	=item EV::dispatch	127	0 as above
		128	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		129	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
91		130
92	Same as C<EV::loop 0>.	131	=item EV::unloop [$how]
93		132
94	=item EV::event $callback	133	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		134	innermost call to EV::loop return.
95		135
96	Creates a new event watcher waiting for nothing, calling the given callback.	136	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		137	fast as possible.
97		138
		139	=item $count = EV::loop_count
		140
		141	Return the number of times the event loop has polled for new
		142	events. Sometiems useful as a generation counter.
		143
		144	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		145
		146	This function rolls together an I/O and a timer watcher for a single
		147	one-shot event without the need for managing a watcher object.
		148
		149	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		150	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		151	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		152	you do not want to wait for some I/O event, specify C<undef> for
		153	C<$fh_or_undef> and C<0> for C<$events>).
		154
		155	If timeout is C<undef> or negative, then there will be no
		156	timeout. Otherwise a EV::timer with this value will be started.
		157
		158	When an error occurs or either the timeout or I/O watcher triggers, then
		159	the callback will be called with the received event set (in general
		160	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		161	C<EV::WRITE> and C<EV::TIMEOUT>).
		162
		163	EV::once doesn't return anything: the watchers stay active till either
		164	of them triggers, then they will be stopped and freed, and the callback
		165	invoked.
		166
		167	=item EV::feed_fd_event ($fd, $revents)
		168
		169	Feed an event on a file descriptor into EV. EV will react to this call as
		170	if the readyness notifications specified by C<$revents> (a combination of
		171	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		172
		173	=item EV::feed_signal_event ($signal)
		174
		175	Feed a signal event into EV. EV will react to this call as if the signal
		176	specified by C<$signal> had occured.
		177
		178	=back
		179
		180
		181	=head2 WATCHER OBJECTS
		182
		183	A watcher is an object that gets created to record your interest in some
		184	event. For instance, if you want to wait for STDIN to become readable, you
		185	would create an EV::io watcher for that:
		186
		187	my $watcher = EV::io *STDIN, EV::READ, sub {
		188	my ($watcher, $revents) = @_;
		189	warn "yeah, STDIN should not be readable without blocking!\n"
		190	};
		191
		192	All watchers can be active (waiting for events) or inactive (paused). Only
		193	active watchers will have their callbacks invoked. All callbacks will be
		194	called with at least two arguments: the watcher and a bitmask of received
		195	events.
		196
		197	Each watcher type has its associated bit in revents, so you can use the
		198	same callback for multiple watchers. The event mask is named after the
		199	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		200	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		201	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		202	uses EV::TIMEOUT).
		203
		204	In the rare case where one wants to create a watcher but not start it at
		205	the same time, each constructor has a variant with a trailing C<_ns> in
		206	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		207
		208	Please note that a watcher will automatically be stopped when the watcher
		209	object is destroyed, so you I<need> to keep the watcher objects returned by
		210	the constructors.
		211
		212	Also, all methods changing some aspect of a watcher (->set, ->priority,
		213	->fh and so on) automatically stop and start it again if it is active,
		214	which means pending events get lost.
		215
		216	=head2 COMMON WATCHER METHODS
		217
		218	This section lists methods common to all watchers.
		219
		220	=over 4
		221
		222	=item $w->start
		223
		224	Starts a watcher if it isn't active already. Does nothing to an already
		225	active watcher. By default, all watchers start out in the active state
		226	(see the description of the C<_ns> variants if you need stopped watchers).
		227
		228	=item $w->stop
		229
		230	Stop a watcher if it is active. Also clear any pending events (events that
		231	have been received but that didn't yet result in a callback invocation),
		232	regardless of whether the watcher was active or not.
		233
		234	=item $bool = $w->is_active
		235
		236	Returns true if the watcher is active, false otherwise.
		237
		238	=item $current_data = $w->data
		239
		240	=item $old_data = $w->data ($new_data)
		241
		242	Queries a freely usable data scalar on the watcher and optionally changes
		243	it. This is a way to associate custom data with a watcher:
		244
		245	my $w = EV::timer 60, 0, sub {
		246	warn $_[0]->data;
		247	};
		248	$w->data ("print me!");
		249
		250	=item $current_cb = $w->cb
		251
		252	=item $old_cb = $w->cb ($new_cb)
		253
		254	Queries the callback on the watcher and optionally changes it. You can do
		255	this at any time without the watcher restarting.
		256
		257	=item $current_priority = $w->priority
		258
		259	=item $old_priority = $w->priority ($new_priority)
		260
		261	Queries the priority on the watcher and optionally changes it. Pending
		262	watchers with higher priority will be invoked first. The valid range of
		263	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		264	-2). If the priority is outside this range it will automatically be
		265	normalised to the nearest valid priority.
		266
		267	The default priority of any newly-created watcher is 0.
		268
		269	Note that the priority semantics have not yet been fleshed out and are
		270	subject to almost certain change.
		271
		272	=item $w->invoke ($revents)
		273
		274	Call the callback now with the given event mask.
		275
		276	=item $w->feed_event ($revents)
		277
		278	Feed some events on this watcher into EV. EV will react to this call as if
		279	the watcher had received the given C<$revents> mask.
		280
		281	=item $revents = $w->clear_pending
		282
		283	If the watcher is pending, this function returns clears its pending status
		284	and returns its C<$revents> bitset (as if its callback was invoked). If the
		285	watcher isn't pending it does nothing and returns C<0>.
		286
		287	=item $previous_state = $w->keepalive ($bool)
		288
		289	Normally, C<EV::loop> will return when there are no active watchers
		290	(which is a "deadlock" because no progress can be made anymore). This is
		291	convinient because it allows you to start your watchers (and your jobs),
		292	call C<EV::loop> once and when it returns you know that all your jobs are
		293	finished (or they forgot to register some watchers for their task :).
		294
		295	Sometimes, however, this gets in your way, for example when you the module
		296	that calls C<EV::loop> (usually the main program) is not the same module
		297	as a long-living watcher (for example a DNS client module written by
		298	somebody else even). Then you might want any outstanding requests to be
		299	handled, but you would not want to keep C<EV::loop> from returning just
		300	because you happen to have this long-running UDP port watcher.
		301
		302	In this case you can clear the keepalive status, which means that even
		303	though your watcher is active, it won't keep C<EV::loop> from returning.
		304
		305	The initial value for keepalive is true (enabled), and you cna change it
		306	any time.
		307
		308	Example: Register an I/O watcher for some UDP socket but do not keep the
		309	event loop from running just because of that watcher.
		310
		311	my $udp_socket = ...
		312	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		313	$udp_watcher->keepalive (0);
		314
		315	=back
		316
		317
		318	=head2 WATCHER TYPES
		319
		320	Each of the following subsections describes a single watcher type.
		321
		322	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		323
		324	=over 4
		325
98	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	326	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
99		327
100	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	328	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
101		329
102	As long as the returned watcher object is alive, call the C<$callback>	330	As long as the returned watcher object is alive, call the C<$callback>
103	when the events specified in C<$eventmask> happen. Initially, the timeout	331	when at least one of events specified in C<$eventmask> occurs.
104	is disabled.
105		332
106	The C<io_ns> variant doesn't add/start the newly created watcher.
107
108	Eventmask can be one or more of these constants ORed together:	333	The $eventmask can be one or more of these constants ORed together:
109		334
110	EV::READ wait until read() wouldn't block anymore	335	EV::READ wait until read() wouldn't block anymore
111	EV::WRITE wait until write() wouldn't block anymore	336	EV::WRITE wait until write() wouldn't block anymore
112	EV::PERSIST stay active after an event occured
113		337
114	=item my $w = EV::timer $after, $repeat, $callback
115
116	=item my $w = EV::timer_ns $after, $repeat, $callback
117
118	Calls the callback after C<$after> seconds. If C<$repeat> is true, the
119	timer will be restarted after the callback returns. This means that the
120	callback would be called roughly every C<$after> seconds, prolonged by the
121	time the callback takes.
122
123	The C<timer_ns> variant doesn't add/start the newly created watcher.	338	The C<io_ns> variant doesn't start (activate) the newly created watcher.
124		339
125	=item my $w = EV::timer_abs $at, $interval, $callback	340	=item $w->set ($fileno_or_fh, $eventmask)
126		341
127	=item my $w = EV::timer_abs_ns $at, $interval, $callback	342	Reconfigures the watcher, see the constructor above for details. Can be
128		343	called at any time.
129	Similar to EV::timer, but the time is given as an absolute point in time
130	(C<$at>), plus an optional C<$interval>.
131
132	If the C<$interval> is zero, then the callback will be called at the time
133	C<$at> if that is in the future, or as soon as possible if its in the
134	past. It will not automatically repeat.
135
136	If the C<$interval> is nonzero, then the watcher will always be scheduled
137	to time out at the next C<$at + integer * $interval> time.
138
139	This can be used to schedule a callback to run at very regular intervals,
140	as long as the processing time is less then the interval (otherwise
141	obviously events will be skipped).
142
143	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.
144
145	=item my $w = EV::signal $signum, $callback
146
147	=item my $w = EV::signal_ns $signum, $callback
148
149	Call the callback when signal $signum is received.
150
151	The C<signal_ns> variant doesn't add/start the newly created watcher.
152
153	=back
154
155	=head1 THE EV::Event CLASS
156
157	All EV functions creating an event watcher (designated by C<my $w =>
158	above) support the following methods on the returned watcher object:
159
160	=over 4
161
162	=item $w->add ($timeout)
163
164	Stops and (re-)starts the event watcher, setting the optional timeout to
165	the given value, or clearing the timeout if none is given.
166
167	=item $w->start
168
169	Stops and (re-)starts the event watcher without touching the timeout.
170
171	=item $w->del
172
173	=item $w->stop
174
175	Stop the event watcher if it was started.
176
177	=item $current_callback = $w->cb
178
179	=item $old_callback = $w->cb ($new_callback)
180
181	Return the previously set callback and optionally set a new one.
182		344
183	=item $current_fh = $w->fh	345	=item $current_fh = $w->fh
184		346
185	=item $old_fh = $w->fh ($new_fh)	347	=item $old_fh = $w->fh ($new_fh)
186		348
190		352
191	=item $old_eventmask = $w->events ($new_eventmask)	353	=item $old_eventmask = $w->events ($new_eventmask)
192		354
193	Returns the previously set event mask and optionally set a new one.	355	Returns the previously set event mask and optionally set a new one.
194		356
		357	=back
		358
		359
		360	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		361
		362	=over 4
		363
		364	=item $w = EV::timer $after, $repeat, $callback
		365
		366	=item $w = EV::timer_ns $after, $repeat, $callback
		367
		368	Calls the callback after C<$after> seconds (which may be fractional). If
		369	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		370	value as $after) after the callback returns.
		371
		372	This means that the callback would be called roughly after C<$after>
		373	seconds, and then every C<$repeat> seconds. The timer does his best not
		374	to drift, but it will not invoke the timer more often then once per event
		375	loop iteration, and might drift in other cases. If that isn't acceptable,
		376	look at EV::periodic, which can provide long-term stable timers.
		377
		378	The timer is based on a monotonic clock, that is, if somebody is sitting
		379	in front of the machine while the timer is running and changes the system
		380	clock, the timer will nevertheless run (roughly) the same time.
		381
		382	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		383
195	=item $w->timeout ($after, $repeat)	384	=item $w->set ($after, $repeat)
196		385
197	Resets the timeout (see C<EV::timer> for details).	386	Reconfigures the watcher, see the constructor above for details. Can be called at
		387	any time.
198		388
199	=item $w->timeout_abs ($at, $interval)	389	=item $w->again
200		390
201	Resets the timeout (see C<EV::timer_abs> for details).	391	Similar to the C<start> method, but has special semantics for repeating timers:
202		392
203	=item $w->priority_set ($priority)	393	If the timer is active and non-repeating, it will be stopped.
204		394
205	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	395	If the timer is active and repeating, reset the timeout to occur
		396	C<$repeat> seconds after now.
206		397
207	=back	398	If the timer is inactive and repeating, start it using the repeat value.
208		399
209	=head1 BUGS	400	Otherwise do nothing.
210		401
211	Lots. Libevent itself isn't well tested and rather buggy, and this module	402	This behaviour is useful when you have a timeout for some IO
212	is quite new at the moment.	403	operation. You create a timer object with the same value for C<$after> and
		404	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		405	on the timeout.
213		406
214	Please note that the epoll method is not, in general, reliable in	407	=back
215	programs that use fork (even if no libveent calls are being made in the	408
216	forked process). Since this is such a common issue, this module will	409
217	force the epoll method in EV to be off unless the global variable	410	=head3 PERIODIC WATCHERS - to cron or not to cron?
218	$EV::ENABLE_EPOLL is set to 1 before loading this module for the first	411
		412	=over 4
		413
		414	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		415
		416	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		417
		418	Similar to EV::timer, but is not based on relative timeouts but on
		419	absolute times. Apart from creating "simple" timers that trigger "at" the
		420	specified time, it can also be used for non-drifting absolute timers and
		421	more complex, cron-like, setups that are not adversely affected by time
		422	jumps (i.e. when the system clock is changed by explicit date -s or other
		423	means such as ntpd). It is also the most complex watcher type in EV.
		424
		425	It has three distinct "modes":
		426
		427	=over 4
		428
		429	=item * absolute timer ($interval = $reschedule_cb = 0)
		430
		431	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		432	will not adjust when a time jump occurs, that is, if it is to be run
		433	at January 1st 2011 then it will run when the system time reaches or
		434	surpasses this time.
		435
		436	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		437
		438	In this mode the watcher will always be scheduled to time out at the
		439	next C<$at + N * $interval> time (for some integer N) and then repeat,
		440	regardless of any time jumps.
		441
		442	This can be used to create timers that do not drift with respect to system
219	time.	443	time:
		444
		445	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		446
		447	That doesn't mean there will always be 3600 seconds in between triggers,
		448	but only that the the clalback will be called when the system time shows a
		449	full hour (UTC).
		450
		451	Another way to think about it (for the mathematically inclined) is that
		452	EV::periodic will try to run the callback in this mode at the next
		453	possible time where C<$time = $at (mod $interval)>, regardless of any time
		454	jumps.
		455
		456	=item * manual reschedule mode ($reschedule_cb = coderef)
		457
		458	In this mode $interval and $at are both being ignored. Instead, each
		459	time the periodic watcher gets scheduled, the reschedule callback
		460	($reschedule_cb) will be called with the watcher as first, and the current
		461	time as second argument.
		462
		463	I<This callback MUST NOT stop or destroy this or any other periodic
		464	watcher, ever>. If you need to stop it, return 1e30 and stop it
		465	afterwards.
		466
		467	It must return the next time to trigger, based on the passed time value
		468	(that is, the lowest time value larger than to the second argument). It
		469	will usually be called just before the callback will be triggered, but
		470	might be called at other times, too.
		471
		472	This can be used to create very complex timers, such as a timer that
		473	triggers on each midnight, local time (actually 24 hours after the last
		474	midnight, to keep the example simple. If you know a way to do it correctly
		475	in about the same space (without requiring elaborate modules), drop me a
		476	note :):
		477
		478	my $daily = EV::periodic 0, 0, sub {
		479	my ($w, $now) = @_;
		480
		481	use Time::Local ();
		482	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		483	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		484	}, sub {
		485	print "it's midnight or likely shortly after, now\n";
		486	};
		487
		488	=back
		489
		490	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		491
		492	=item $w->set ($at, $interval, $reschedule_cb)
		493
		494	Reconfigures the watcher, see the constructor above for details. Can be called at
		495	any time.
		496
		497	=item $w->again
		498
		499	Simply stops and starts the watcher again.
		500
		501	=item $time = $w->at
		502
		503	Return the time that the watcher is expected to trigger next.
		504
		505	=back
		506
		507
		508	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		509
		510	=over 4
		511
		512	=item $w = EV::signal $signal, $callback
		513
		514	=item $w = EV::signal_ns $signal, $callback
		515
		516	Call the callback when $signal is received (the signal can be specified by
		517	number or by name, just as with C<kill> or C<%SIG>).
		518
		519	EV will grab the signal for the process (the kernel only allows one
		520	component to receive a signal at a time) when you start a signal watcher,
		521	and removes it again when you stop it. Perl does the same when you
		522	add/remove callbacks to C<%SIG>, so watch out.
		523
		524	You can have as many signal watchers per signal as you want.
		525
		526	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		527
		528	=item $w->set ($signal)
		529
		530	Reconfigures the watcher, see the constructor above for details. Can be
		531	called at any time.
		532
		533	=item $current_signum = $w->signal
		534
		535	=item $old_signum = $w->signal ($new_signal)
		536
		537	Returns the previously set signal (always as a number not name) and
		538	optionally set a new one.
		539
		540	=back
		541
		542
		543	=head3 CHILD WATCHERS - watch out for process status changes
		544
		545	=over 4
		546
		547	=item $w = EV::child $pid, $callback
		548
		549	=item $w = EV::child_ns $pid, $callback
		550
		551	Call the callback when a status change for pid C<$pid> (or any pid if
		552	C<$pid> is 0) has been received. More precisely: when the process receives
		553	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		554	changed/zombie children and call the callback.
		555
		556	It is valid (and fully supported) to install a child watcher after a child
		557	has exited but before the event loop has started its next iteration (for
		558	example, first you C<fork>, then the new child process might exit, and
		559	only then do you install a child watcher in the parent for the new pid).
		560
		561	You can access both exit (or tracing) status and pid by using the
		562	C<rstatus> and C<rpid> methods on the watcher object.
		563
		564	You can have as many pid watchers per pid as you want, they will all be
		565	called.
		566
		567	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		568
		569	=item $w->set ($pid)
		570
		571	Reconfigures the watcher, see the constructor above for details. Can be called at
		572	any time.
		573
		574	=item $current_pid = $w->pid
		575
		576	=item $old_pid = $w->pid ($new_pid)
		577
		578	Returns the previously set process id and optionally set a new one.
		579
		580	=item $exit_status = $w->rstatus
		581
		582	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		583	in perlfunc).
		584
		585	=item $pid = $w->rpid
		586
		587	Return the pid of the awaited child (useful when you have installed a
		588	watcher for all pids).
		589
		590	=back
		591
		592
		593	=head3 STAT WATCHERS - did the file attributes just change?
		594
		595	=over 4
		596
		597	=item $w = EV::stat $path, $interval, $callback
		598
		599	=item $w = EV::stat_ns $path, $interval, $callback
		600
		601	Call the callback when a file status change has been detected on
		602	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		603	to "path does not exist" is a status change like any other.
		604
		605	The C<$interval> is a recommended polling interval for systems where
		606	OS-supported change notifications don't exist or are not supported. If
		607	you use C<0> then an unspecified default is used (which is highly
		608	recommended!), which is to be expected to be around five seconds usually.
		609
		610	This watcher type is not meant for massive numbers of stat watchers,
		611	as even with OS-supported change notifications, this can be
		612	resource-intensive.
		613
		614	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		615
		616	=item ... = $w->stat
		617
		618	This call is very similar to the perl C<stat> built-in: It stats (using
		619	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		620	well as EV's idea of the current stat values) to the values found.
		621
		622	In scalar context, a boolean is return indicating success or failure of
		623	the stat. In list context, the same 13-value list as with stat is returned
		624	(except that the blksize and blocks fields are not reliable).
		625
		626	In the case of an error, errno is set to C<ENOENT> (regardless of the
		627	actual error value) and the C<nlink> value is forced to zero (if the stat
		628	was successful then nlink is guaranteed to be non-zero).
		629
		630	See also the next two entries for more info.
		631
		632	=item ... = $w->attr
		633
		634	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		635	the values most recently detected by EV. See the next entry for more info.
		636
		637	=item ... = $w->prev
		638
		639	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		640	the previous set of values, before the change.
		641
		642	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		643	to the values found I<before> a change was detected, while C<< $w->attr >>
		644	returns the values found leading to the change detection. The difference (if any)
		645	between C<prev> and C<attr> is what triggered the callback.
		646
		647	If you did something to the filesystem object and do not want to trigger
		648	yet another change, you can call C<stat> to update EV's idea of what the
		649	current attributes are.
		650
		651	=item $w->set ($path, $interval)
		652
		653	Reconfigures the watcher, see the constructor above for details. Can be
		654	called at any time.
		655
		656	=item $current_path = $w->path
		657
		658	=item $old_path = $w->path ($new_path)
		659
		660	Returns the previously set path and optionally set a new one.
		661
		662	=item $current_interval = $w->interval
		663
		664	=item $old_interval = $w->interval ($new_interval)
		665
		666	Returns the previously set interval and optionally set a new one. Can be
		667	used to query the actual interval used.
		668
		669	=back
		670
		671
		672	=head3 IDLE WATCHERS - when you've got nothing better to do...
		673
		674	=over 4
		675
		676	=item $w = EV::idle $callback
		677
		678	=item $w = EV::idle_ns $callback
		679
		680	Call the callback when there are no other pending watchers of the same or
		681	higher priority (excluding check, prepare and other idle watchers of the
		682	same or lower priority, of course). They are called idle watchers because
		683	when the watcher is the highest priority pending event in the process, the
		684	process is considered to be idle at that priority.
		685
		686	If you want a watcher that is only ever called when I<no> other events are
		687	outstanding you have to set the priority to C<EV::MINPRI>.
		688
		689	The process will not block as long as any idle watchers are active, and
		690	they will be called repeatedly until stopped.
		691
		692	For example, if you have idle watchers at priority C<0> and C<1>, and
		693	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		694	and the I/O watcher will always run when ready. Only when the idle watcher
		695	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		696	pending with the C<0>-priority idle watcher be invoked.
		697
		698	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		699
		700	=back
		701
		702
		703	=head3 PREPARE WATCHERS - customise your event loop!
		704
		705	=over 4
		706
		707	=item $w = EV::prepare $callback
		708
		709	=item $w = EV::prepare_ns $callback
		710
		711	Call the callback just before the process would block. You can still
		712	create/modify any watchers at this point.
		713
		714	See the EV::check watcher, below, for explanations and an example.
		715
		716	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		717
		718	=back
		719
		720
		721	=head3 CHECK WATCHERS - customise your event loop even more!
		722
		723	=over 4
		724
		725	=item $w = EV::check $callback
		726
		727	=item $w = EV::check_ns $callback
		728
		729	Call the callback just after the process wakes up again (after it has
		730	gathered events), but before any other callbacks have been invoked.
		731
		732	This is used to integrate other event-based software into the EV
		733	mainloop: You register a prepare callback and in there, you create io and
		734	timer watchers as required by the other software. Here is a real-world
		735	example of integrating Net::SNMP (with some details left out):
		736
		737	our @snmp_watcher;
		738
		739	our $snmp_prepare = EV::prepare sub {
		740	# do nothing unless active
		741	$dispatcher->{_event_queue_h}
		742	or return;
		743
		744	# make the dispatcher handle any outstanding stuff
		745	... not shown
		746
		747	# create an I/O watcher for each and every socket
		748	@snmp_watcher = (
		749	(map { EV::io $_, EV::READ, sub { } }
		750	keys %{ $dispatcher->{_descriptors} }),
		751
		752	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		753	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		754	0, sub { },
		755	);
		756	};
		757
		758	The callbacks are irrelevant (and are not even being called), the
		759	only purpose of those watchers is to wake up the process as soon as
		760	one of those events occurs (socket readable, or timer timed out). The
		761	corresponding EV::check watcher will then clean up:
		762
		763	our $snmp_check = EV::check sub {
		764	# destroy all watchers
		765	@snmp_watcher = ();
		766
		767	# make the dispatcher handle any new stuff
		768	... not shown
		769	};
		770
		771	The callbacks of the created watchers will not be called as the watchers
		772	are destroyed before this cna happen (remember EV::check gets called
		773	first).
		774
		775	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		776
		777	=back
		778
		779
		780	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		781
		782	Fork watchers are called when a C<fork ()> was detected. The invocation
		783	is done before the event loop blocks next and before C<check> watchers
		784	are being called, and only in the child after the fork.
		785
		786	=over 4
		787
		788	=item $w = EV::fork $callback
		789
		790	=item $w = EV::fork_ns $callback
		791
		792	Call the callback before the event loop is resumed in the child process
		793	after a fork.
		794
		795	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		796
		797	=back
		798
		799
		800	=head1 PERL SIGNALS
		801
		802	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		803	with EV is as the same as any other C library: Perl-signals will only be
		804	handled when Perl runs, which means your signal handler might be invoked
		805	only the next time an event callback is invoked.
		806
		807	The solution is to use EV signal watchers (see C<EV::signal>), which will
		808	ensure proper operations with regards to other event watchers.
		809
		810	If you cannot do this for whatever reason, you can also force a watcher
		811	to be called on every event loop iteration by installing a C<EV::check>
		812	watcher:
		813
		814	my $async_check = EV::check sub { };
		815
		816	This ensures that perl shortly gets into control for a short time, and
		817	also ensures slower overall operation.
		818
		819	=head1 THREADS
		820
		821	Threads are not supported by this module in any way. Perl pseudo-threads
		822	is evil stuff and must die. As soon as Perl gains real threads I will work
		823	on thread support for it.
		824
		825	=head1 FORK
		826
		827	Most of the "improved" event delivering mechanisms of modern operating
		828	systems have quite a few problems with fork(2) (to put it bluntly: it is
		829	not supported and usually destructive). Libev makes it possible to work
		830	around this by having a function that recreates the kernel state after
		831	fork in the child.
		832
		833	On non-win32 platforms, this module requires the pthread_atfork
		834	functionality to do this automatically for you. This function is quite
		835	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		836	negligible, because everything the function currently does is set a flag
		837	that is checked only when the event loop gets used the next time, so when
		838	you do fork but not use EV, the overhead is minimal.
		839
		840	On win32, there is no notion of fork so all this doesn't apply, of course.
220		841
221	=cut	842	=cut
222		843
223	our $NPRI = 4;	844	our $DIED = sub {
224	our $BASE;	845	warn "EV: error in callback (ignoring): $@";
225	our $ENABLE_EPOLL;	846	};
226		847
227	{	848	default_loop
228	local $ENV{EVENT_NOEPOLL};	849	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
229	$ENV{EVENT_NOEPOLL} = 1 unless $ENABLE_EPOLL;
230	$BASE = init;
231	}
232
233	priority_init $NPRI;
234
235	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
236		850
237	1;	851	1;
238		852
239	=head1 SEE ALSO	853	=head1 SEE ALSO
240		854
241	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	855	L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
242	L<EV::AnyEvent>.	856	event loop), L<Coro::EV> (efficient coroutines with EV).
243		857
244	=head1 AUTHOR	858	=head1 AUTHOR
245		859
246	Marc Lehmann <schmorp@schmorp.de>	860	Marc Lehmann <schmorp@schmorp.de>
247	http://home.schmorp.de/	861	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs. Revision 1.72 by root, Thu Dec 20 07:12:57 2007 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.6 by root, Sat Oct 27 07:30:10 2007 UTC vs.
Revision 1.72 by root, Thu Dec 20 07:12:57 2007 UTC