[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 1.71 by root, Mon Dec 17 07:24:12 2007 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothign received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};	30	};
35	$w->timeout (10);	31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
36		39
		40	my $w = EV::child 666, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
		44
		45	# STAT CHANGES
		46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
		49	};
		50
37	# MAINLOOP	51	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		55
43	=head1 DESCRIPTION	56	=head1 DESCRIPTION
44		57
45	This module provides an interface to libevent	58	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
47	yourself with its documentation and source code to be able to use this	60	below is comprehensive, one might also consult the documentation of libev
48	module fully.	61	itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
49		62	watcher semantics or some discussion on the available backends, or how to
50	Please note thta this module disables the libevent EPOLL method by	63	force a specific backend with C<LIBEV_FLAGS>, or just about in any case
51	default, see BUGS, below, if you need to enable it.	64	because it has much more detailed information.
52		65
53	=cut	66	=cut
54		67
55	package EV;	68	package EV;
56		69
57	use strict;	70	use strict;
58		71
59	BEGIN {	72	BEGIN {
60	our $VERSION = '0.01';	73	our $VERSION = '1.86';
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	=head1 BASIC INTERFACE
68		92
		93	=over 4
		94
69	=item $EV::NPRI	95	=item $EV::DIED
70		96
71	How many priority levels are available.	97	Must contain a reference to a function that is called when a callback
		98	throws an exception (with $@ containing the error). The default prints an
		99	informative message and continues.
		100
		101	If this callback throws an exception it will be silently ignored.
		102
		103	=item $time = EV::time
		104
		105	Returns the current time in (fractional) seconds since the epoch.
72		106
73	=item $time = EV::now	107	=item $time = EV::now
74		108
75	Returns the time in (fractional) seconds since the epoch.	109	Returns the time the last event loop iteration has been started. This
76		110	is the time that (relative) timers are based on, and refering to it is
77	=item $version = EV::version	111	usually faster then calling EV::time.
78		112
79	=item $method = EV::method	113	=item $method = EV::method
80		114
81	Return version string and event polling method used.	115	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		116	or EV::METHOD_EPOLL).
82		117
83	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	118	=item EV::loop [$flags]
84		119
85	=item EV::loopexit $after	120	Begin checking for events and calling callbacks. It returns when a
		121	callback calls EV::unloop.
86		122
87	Exit any active loop or dispatch after C<$after> seconds or immediately if	123	The $flags argument can be one of the following:
88	C<$after> is missing or zero.
89		124
90	=item EV::dispatch	125	0 as above
		126	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		127	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
91		128
92	Same as C<EV::loop 0>.	129	=item EV::unloop [$how]
93		130
94	=item EV::event $callback	131	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		132	innermost call to EV::loop return.
95		133
96	Creates a new event watcher waiting for nothing, calling the given callback.	134	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		135	fast as possible.
97		136
		137	=item $count = EV::loop_count
		138
		139	Return the number of times the event loop has polled for new
		140	events. Sometiems useful as a generation counter.
		141
		142	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		143
		144	This function rolls together an I/O and a timer watcher for a single
		145	one-shot event without the need for managing a watcher object.
		146
		147	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		148	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		149	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		150	you do not want to wait for some I/O event, specify C<undef> for
		151	C<$fh_or_undef> and C<0> for C<$events>).
		152
		153	If timeout is C<undef> or negative, then there will be no
		154	timeout. Otherwise a EV::timer with this value will be started.
		155
		156	When an error occurs or either the timeout or I/O watcher triggers, then
		157	the callback will be called with the received event set (in general
		158	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		159	C<EV::WRITE> and C<EV::TIMEOUT>).
		160
		161	EV::once doesn't return anything: the watchers stay active till either
		162	of them triggers, then they will be stopped and freed, and the callback
		163	invoked.
		164
		165	=item EV::feed_fd_event ($fd, $revents)
		166
		167	Feed an event on a file descriptor into EV. EV will react to this call as
		168	if the readyness notifications specified by C<$revents> (a combination of
		169	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		170
		171	=item EV::feed_signal_event ($signal)
		172
		173	Feed a signal event into EV. EV will react to this call as if the signal
		174	specified by C<$signal> had occured.
		175
		176	=back
		177
		178
		179	=head2 WATCHER OBJECTS
		180
		181	A watcher is an object that gets created to record your interest in some
		182	event. For instance, if you want to wait for STDIN to become readable, you
		183	would create an EV::io watcher for that:
		184
		185	my $watcher = EV::io *STDIN, EV::READ, sub {
		186	my ($watcher, $revents) = @_;
		187	warn "yeah, STDIN should not be readable without blocking!\n"
		188	};
		189
		190	All watchers can be active (waiting for events) or inactive (paused). Only
		191	active watchers will have their callbacks invoked. All callbacks will be
		192	called with at least two arguments: the watcher and a bitmask of received
		193	events.
		194
		195	Each watcher type has its associated bit in revents, so you can use the
		196	same callback for multiple watchers. The event mask is named after the
		197	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		198	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		199	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		200	uses EV::TIMEOUT).
		201
		202	In the rare case where one wants to create a watcher but not start it at
		203	the same time, each constructor has a variant with a trailing C<_ns> in
		204	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		205
		206	Please note that a watcher will automatically be stopped when the watcher
		207	object is destroyed, so you I<need> to keep the watcher objects returned by
		208	the constructors.
		209
		210	Also, all methods changing some aspect of a watcher (->set, ->priority,
		211	->fh and so on) automatically stop and start it again if it is active,
		212	which means pending events get lost.
		213
		214	=head2 COMMON WATCHER METHODS
		215
		216	This section lists methods common to all watchers.
		217
		218	=over 4
		219
		220	=item $w->start
		221
		222	Starts a watcher if it isn't active already. Does nothing to an already
		223	active watcher. By default, all watchers start out in the active state
		224	(see the description of the C<_ns> variants if you need stopped watchers).
		225
		226	=item $w->stop
		227
		228	Stop a watcher if it is active. Also clear any pending events (events that
		229	have been received but that didn't yet result in a callback invocation),
		230	regardless of whether the watcher was active or not.
		231
		232	=item $bool = $w->is_active
		233
		234	Returns true if the watcher is active, false otherwise.
		235
		236	=item $current_data = $w->data
		237
		238	=item $old_data = $w->data ($new_data)
		239
		240	Queries a freely usable data scalar on the watcher and optionally changes
		241	it. This is a way to associate custom data with a watcher:
		242
		243	my $w = EV::timer 60, 0, sub {
		244	warn $_[0]->data;
		245	};
		246	$w->data ("print me!");
		247
		248	=item $current_cb = $w->cb
		249
		250	=item $old_cb = $w->cb ($new_cb)
		251
		252	Queries the callback on the watcher and optionally changes it. You can do
		253	this at any time without the watcher restarting.
		254
		255	=item $current_priority = $w->priority
		256
		257	=item $old_priority = $w->priority ($new_priority)
		258
		259	Queries the priority on the watcher and optionally changes it. Pending
		260	watchers with higher priority will be invoked first. The valid range of
		261	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		262	-2). If the priority is outside this range it will automatically be
		263	normalised to the nearest valid priority.
		264
		265	The default priority of any newly-created watcher is 0.
		266
		267	Note that the priority semantics have not yet been fleshed out and are
		268	subject to almost certain change.
		269
		270	=item $w->invoke ($revents)
		271
		272	Call the callback now with the given event mask.
		273
		274	=item $w->feed_event ($revents)
		275
		276	Feed some events on this watcher into EV. EV will react to this call as if
		277	the watcher had received the given C<$revents> mask.
		278
		279	=item $revents = $w->clear_pending
		280
		281	If the watcher is pending, this function returns clears its pending status
		282	and returns its C<$revents> bitset (as if its callback was invoked). If the
		283	watcher isn't pending it does nothing and returns C<0>.
		284
		285	=item $previous_state = $w->keepalive ($bool)
		286
		287	Normally, C<EV::loop> will return when there are no active watchers
		288	(which is a "deadlock" because no progress can be made anymore). This is
		289	convinient because it allows you to start your watchers (and your jobs),
		290	call C<EV::loop> once and when it returns you know that all your jobs are
		291	finished (or they forgot to register some watchers for their task :).
		292
		293	Sometimes, however, this gets in your way, for example when you the module
		294	that calls C<EV::loop> (usually the main program) is not the same module
		295	as a long-living watcher (for example a DNS client module written by
		296	somebody else even). Then you might want any outstanding requests to be
		297	handled, but you would not want to keep C<EV::loop> from returning just
		298	because you happen to have this long-running UDP port watcher.
		299
		300	In this case you can clear the keepalive status, which means that even
		301	though your watcher is active, it won't keep C<EV::loop> from returning.
		302
		303	The initial value for keepalive is true (enabled), and you cna change it
		304	any time.
		305
		306	Example: Register an I/O watcher for some UDP socket but do not keep the
		307	event loop from running just because of that watcher.
		308
		309	my $udp_socket = ...
		310	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		311	$udp_watcher->keepalive (0);
		312
		313	=back
		314
		315
		316	=head2 WATCHER TYPES
		317
		318	Each of the following subsections describes a single watcher type.
		319
		320	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		321
		322	=over 4
		323
98	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	324	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
99		325
100	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	326	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
101		327
102	As long as the returned watcher object is alive, call the C<$callback>	328	As long as the returned watcher object is alive, call the C<$callback>
103	when the events specified in C<$eventmask> happen. Initially, the timeout	329	when at least one of events specified in C<$eventmask> occurs.
104	is disabled.
105		330
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:	331	The $eventmask can be one or more of these constants ORed together:
109		332
110	EV::READ wait until read() wouldn't block anymore	333	EV::READ wait until read() wouldn't block anymore
111	EV::WRITE wait until write() wouldn't block anymore	334	EV::WRITE wait until write() wouldn't block anymore
112	EV::PERSIST stay active after an event occured
113		335
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.	336	The C<io_ns> variant doesn't start (activate) the newly created watcher.
124		337
125	=item my $w = EV::timer_abs $at, $interval, $callback	338	=item $w->set ($fileno_or_fh, $eventmask)
126		339
127	=item my $w = EV::timer_abs_ns $at, $interval, $callback	340	Reconfigures the watcher, see the constructor above for details. Can be
128		341	called at any time.
129	Similar to EV::timer, but the time is given as an absolute point in time
130	(C<$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		342
183	=item $current_fh = $w->fh	343	=item $current_fh = $w->fh
184		344
185	=item $old_fh = $w->fh ($new_fh)	345	=item $old_fh = $w->fh ($new_fh)
186		346
190		350
191	=item $old_eventmask = $w->events ($new_eventmask)	351	=item $old_eventmask = $w->events ($new_eventmask)
192		352
193	Returns the previously set event mask and optionally set a new one.	353	Returns the previously set event mask and optionally set a new one.
194		354
		355	=back
		356
		357
		358	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		359
		360	=over 4
		361
		362	=item $w = EV::timer $after, $repeat, $callback
		363
		364	=item $w = EV::timer_ns $after, $repeat, $callback
		365
		366	Calls the callback after C<$after> seconds (which may be fractional). If
		367	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		368	value as $after) after the callback returns.
		369
		370	This means that the callback would be called roughly after C<$after>
		371	seconds, and then every C<$repeat> seconds. The timer does his best not
		372	to drift, but it will not invoke the timer more often then once per event
		373	loop iteration, and might drift in other cases. If that isn't acceptable,
		374	look at EV::periodic, which can provide long-term stable timers.
		375
		376	The timer is based on a monotonic clock, that is, if somebody is sitting
		377	in front of the machine while the timer is running and changes the system
		378	clock, the timer will nevertheless run (roughly) the same time.
		379
		380	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		381
195	=item $w->timeout ($after, $repeat)	382	=item $w->set ($after, $repeat)
196		383
197	Resets the timeout (see C<EV::timer> for details).	384	Reconfigures the watcher, see the constructor above for details. Can be called at
		385	any time.
198		386
199	=item $w->timeout_abs ($at, $interval)	387	=item $w->again
200		388
201	Resets the timeout (see C<EV::timer_abs> for details).	389	Similar to the C<start> method, but has special semantics for repeating timers:
202		390
203	=item $w->priority_set ($priority)	391	If the timer is active and non-repeating, it will be stopped.
204		392
205	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	393	If the timer is active and repeating, reset the timeout to occur
		394	C<$repeat> seconds after now.
206		395
207	=back	396	If the timer is inactive and repeating, start it using the repeat value.
208		397
209	=head1 BUGS	398	Otherwise do nothing.
210		399
211	Lots. Libevent itself isn't well tested and rather buggy, and this module	400	This behaviour is useful when you have a timeout for some IO
212	is quite new at the moment.	401	operation. You create a timer object with the same value for C<$after> and
		402	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		403	on the timeout.
213		404
214	Please note that the epoll method is not, in general, reliable in	405	=back
215	programs that use fork (even if no libveent calls are being made in the	406
216	forked process). Since this is such a common issue, this module will	407
217	force the epoll method in EV to be off unless the global variable	408	=head3 PERIODIC WATCHERS - to cron or not to cron?
218	$EV::ENABLE_EPOLL is set to 1 before loading this module for the first	409
		410	=over 4
		411
		412	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		413
		414	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		415
		416	Similar to EV::timer, but is not based on relative timeouts but on
		417	absolute times. Apart from creating "simple" timers that trigger "at" the
		418	specified time, it can also be used for non-drifting absolute timers and
		419	more complex, cron-like, setups that are not adversely affected by time
		420	jumps (i.e. when the system clock is changed by explicit date -s or other
		421	means such as ntpd). It is also the most complex watcher type in EV.
		422
		423	It has three distinct "modes":
		424
		425	=over 4
		426
		427	=item * absolute timer ($interval = $reschedule_cb = 0)
		428
		429	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		430	will not adjust when a time jump occurs, that is, if it is to be run
		431	at January 1st 2011 then it will run when the system time reaches or
		432	surpasses this time.
		433
		434	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		435
		436	In this mode the watcher will always be scheduled to time out at the
		437	next C<$at + N * $interval> time (for some integer N) and then repeat,
		438	regardless of any time jumps.
		439
		440	This can be used to create timers that do not drift with respect to system
219	time.	441	time:
		442
		443	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		444
		445	That doesn't mean there will always be 3600 seconds in between triggers,
		446	but only that the the clalback will be called when the system time shows a
		447	full hour (UTC).
		448
		449	Another way to think about it (for the mathematically inclined) is that
		450	EV::periodic will try to run the callback in this mode at the next
		451	possible time where C<$time = $at (mod $interval)>, regardless of any time
		452	jumps.
		453
		454	=item * manual reschedule mode ($reschedule_cb = coderef)
		455
		456	In this mode $interval and $at are both being ignored. Instead, each
		457	time the periodic watcher gets scheduled, the reschedule callback
		458	($reschedule_cb) will be called with the watcher as first, and the current
		459	time as second argument.
		460
		461	I<This callback MUST NOT stop or destroy this or any other periodic
		462	watcher, ever>. If you need to stop it, return 1e30 and stop it
		463	afterwards.
		464
		465	It must return the next time to trigger, based on the passed time value
		466	(that is, the lowest time value larger than to the second argument). It
		467	will usually be called just before the callback will be triggered, but
		468	might be called at other times, too.
		469
		470	This can be used to create very complex timers, such as a timer that
		471	triggers on each midnight, local time (actually 24 hours after the last
		472	midnight, to keep the example simple. If you know a way to do it correctly
		473	in about the same space (without requiring elaborate modules), drop me a
		474	note :):
		475
		476	my $daily = EV::periodic 0, 0, sub {
		477	my ($w, $now) = @_;
		478
		479	use Time::Local ();
		480	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		481	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		482	}, sub {
		483	print "it's midnight or likely shortly after, now\n";
		484	};
		485
		486	=back
		487
		488	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		489
		490	=item $w->set ($at, $interval, $reschedule_cb)
		491
		492	Reconfigures the watcher, see the constructor above for details. Can be called at
		493	any time.
		494
		495	=item $w->again
		496
		497	Simply stops and starts the watcher again.
		498
		499	=item $time = $w->at
		500
		501	Return the time that the watcher is expected to trigger next.
		502
		503	=back
		504
		505
		506	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		507
		508	=over 4
		509
		510	=item $w = EV::signal $signal, $callback
		511
		512	=item $w = EV::signal_ns $signal, $callback
		513
		514	Call the callback when $signal is received (the signal can be specified by
		515	number or by name, just as with C<kill> or C<%SIG>).
		516
		517	EV will grab the signal for the process (the kernel only allows one
		518	component to receive a signal at a time) when you start a signal watcher,
		519	and removes it again when you stop it. Perl does the same when you
		520	add/remove callbacks to C<%SIG>, so watch out.
		521
		522	You can have as many signal watchers per signal as you want.
		523
		524	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		525
		526	=item $w->set ($signal)
		527
		528	Reconfigures the watcher, see the constructor above for details. Can be
		529	called at any time.
		530
		531	=item $current_signum = $w->signal
		532
		533	=item $old_signum = $w->signal ($new_signal)
		534
		535	Returns the previously set signal (always as a number not name) and
		536	optionally set a new one.
		537
		538	=back
		539
		540
		541	=head3 CHILD WATCHERS - watch out for process status changes
		542
		543	=over 4
		544
		545	=item $w = EV::child $pid, $callback
		546
		547	=item $w = EV::child_ns $pid, $callback
		548
		549	Call the callback when a status change for pid C<$pid> (or any pid if
		550	C<$pid> is 0) has been received. More precisely: when the process receives
		551	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		552	changed/zombie children and call the callback.
		553
		554	It is valid (and fully supported) to install a child watcher after a child
		555	has exited but before the event loop has started its next iteration (for
		556	example, first you C<fork>, then the new child process might exit, and
		557	only then do you install a child watcher in the parent for the new pid).
		558
		559	You can access both exit (or tracing) status and pid by using the
		560	C<rstatus> and C<rpid> methods on the watcher object.
		561
		562	You can have as many pid watchers per pid as you want, they will all be
		563	called.
		564
		565	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		566
		567	=item $w->set ($pid)
		568
		569	Reconfigures the watcher, see the constructor above for details. Can be called at
		570	any time.
		571
		572	=item $current_pid = $w->pid
		573
		574	=item $old_pid = $w->pid ($new_pid)
		575
		576	Returns the previously set process id and optionally set a new one.
		577
		578	=item $exit_status = $w->rstatus
		579
		580	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		581	in perlfunc).
		582
		583	=item $pid = $w->rpid
		584
		585	Return the pid of the awaited child (useful when you have installed a
		586	watcher for all pids).
		587
		588	=back
		589
		590
		591	=head3 STAT WATCHERS - did the file attributes just change?
		592
		593	=over 4
		594
		595	=item $w = EV::stat $path, $interval, $callback
		596
		597	=item $w = EV::stat_ns $path, $interval, $callback
		598
		599	Call the callback when a file status change has been detected on
		600	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		601	to "path does not exist" is a status change like any other.
		602
		603	The C<$interval> is a recommended polling interval for systems where
		604	OS-supported change notifications don't exist or are not supported. If
		605	you use C<0> then an unspecified default is used (which is highly
		606	recommended!), which is to be expected to be around five seconds usually.
		607
		608	This watcher type is not meant for massive numbers of stat watchers,
		609	as even with OS-supported change notifications, this can be
		610	resource-intensive.
		611
		612	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		613
		614	=item ... = $w->stat
		615
		616	This call is very similar to the perl C<stat> built-in: It stats (using
		617	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		618	well as EV's idea of the current stat values) to the values found.
		619
		620	In scalar context, a boolean is return indicating success or failure of
		621	the stat. In list context, the same 13-value list as with stat is returned
		622	(except that the blksize and blocks fields are not reliable).
		623
		624	In the case of an error, errno is set to C<ENOENT> (regardless of the
		625	actual error value) and the C<nlink> value is forced to zero (if the stat
		626	was successful then nlink is guaranteed to be non-zero).
		627
		628	See also the next two entries for more info.
		629
		630	=item ... = $w->attr
		631
		632	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		633	the values most recently detected by EV. See the next entry for more info.
		634
		635	=item ... = $w->prev
		636
		637	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		638	the previous set of values, before the change.
		639
		640	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		641	to the values found I<before> a change was detected, while C<< $w->attr >>
		642	returns the values found leading to the change detection. The difference (if any)
		643	between C<prev> and C<attr> is what triggered the callback.
		644
		645	If you did something to the filesystem object and do not want to trigger
		646	yet another change, you can call C<stat> to update EV's idea of what the
		647	current attributes are.
		648
		649	=item $w->set ($path, $interval)
		650
		651	Reconfigures the watcher, see the constructor above for details. Can be
		652	called at any time.
		653
		654	=item $current_path = $w->path
		655
		656	=item $old_path = $w->path ($new_path)
		657
		658	Returns the previously set path and optionally set a new one.
		659
		660	=item $current_interval = $w->interval
		661
		662	=item $old_interval = $w->interval ($new_interval)
		663
		664	Returns the previously set interval and optionally set a new one. Can be
		665	used to query the actual interval used.
		666
		667	=back
		668
		669
		670	=head3 IDLE WATCHERS - when you've got nothing better to do...
		671
		672	=over 4
		673
		674	=item $w = EV::idle $callback
		675
		676	=item $w = EV::idle_ns $callback
		677
		678	Call the callback when there are no other pending watchers of the same or
		679	higher priority (excluding check, prepare and other idle watchers of the
		680	same or lower priority, of course). They are called idle watchers because
		681	when the watcher is the highest priority pending event in the process, the
		682	process is considered to be idle at that priority.
		683
		684	If you want a watcher that is only ever called when I<no> other events are
		685	outstanding you have to set the priority to C<EV::MINPRI>.
		686
		687	The process will not block as long as any idle watchers are active, and
		688	they will be called repeatedly until stopped.
		689
		690	For example, if you have idle watchers at priority C<0> and C<1>, and
		691	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		692	and the I/O watcher will always run when ready. Only when the idle watcher
		693	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		694	pending with the C<0>-priority idle watcher be invoked.
		695
		696	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		697
		698	=back
		699
		700
		701	=head3 PREPARE WATCHERS - customise your event loop!
		702
		703	=over 4
		704
		705	=item $w = EV::prepare $callback
		706
		707	=item $w = EV::prepare_ns $callback
		708
		709	Call the callback just before the process would block. You can still
		710	create/modify any watchers at this point.
		711
		712	See the EV::check watcher, below, for explanations and an example.
		713
		714	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		715
		716	=back
		717
		718
		719	=head3 CHECK WATCHERS - customise your event loop even more!
		720
		721	=over 4
		722
		723	=item $w = EV::check $callback
		724
		725	=item $w = EV::check_ns $callback
		726
		727	Call the callback just after the process wakes up again (after it has
		728	gathered events), but before any other callbacks have been invoked.
		729
		730	This is used to integrate other event-based software into the EV
		731	mainloop: You register a prepare callback and in there, you create io and
		732	timer watchers as required by the other software. Here is a real-world
		733	example of integrating Net::SNMP (with some details left out):
		734
		735	our @snmp_watcher;
		736
		737	our $snmp_prepare = EV::prepare sub {
		738	# do nothing unless active
		739	$dispatcher->{_event_queue_h}
		740	or return;
		741
		742	# make the dispatcher handle any outstanding stuff
		743	... not shown
		744
		745	# create an I/O watcher for each and every socket
		746	@snmp_watcher = (
		747	(map { EV::io $_, EV::READ, sub { } }
		748	keys %{ $dispatcher->{_descriptors} }),
		749
		750	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		751	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		752	0, sub { },
		753	);
		754	};
		755
		756	The callbacks are irrelevant (and are not even being called), the
		757	only purpose of those watchers is to wake up the process as soon as
		758	one of those events occurs (socket readable, or timer timed out). The
		759	corresponding EV::check watcher will then clean up:
		760
		761	our $snmp_check = EV::check sub {
		762	# destroy all watchers
		763	@snmp_watcher = ();
		764
		765	# make the dispatcher handle any new stuff
		766	... not shown
		767	};
		768
		769	The callbacks of the created watchers will not be called as the watchers
		770	are destroyed before this cna happen (remember EV::check gets called
		771	first).
		772
		773	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		774
		775	=back
		776
		777
		778	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		779
		780	Fork watchers are called when a C<fork ()> was detected. The invocation
		781	is done before the event loop blocks next and before C<check> watchers
		782	are being called, and only in the child after the fork.
		783
		784	=over 4
		785
		786	=item $w = EV::fork $callback
		787
		788	=item $w = EV::fork_ns $callback
		789
		790	Call the callback before the event loop is resumed in the child process
		791	after a fork.
		792
		793	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		794
		795	=back
		796
		797
		798	=head1 PERL SIGNALS
		799
		800	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		801	with EV is as the same as any other C library: Perl-signals will only be
		802	handled when Perl runs, which means your signal handler might be invoked
		803	only the next time an event callback is invoked.
		804
		805	The solution is to use EV signal watchers (see C<EV::signal>), which will
		806	ensure proper operations with regards to other event watchers.
		807
		808	If you cannot do this for whatever reason, you can also force a watcher
		809	to be called on every event loop iteration by installing a C<EV::check>
		810	watcher:
		811
		812	my $async_check = EV::check sub { };
		813
		814	This ensures that perl shortly gets into control for a short time, and
		815	also ensures slower overall operation.
		816
		817	=head1 THREADS
		818
		819	Threads are not supported by this module in any way. Perl pseudo-threads
		820	is evil stuff and must die. As soon as Perl gains real threads I will work
		821	on thread support for it.
		822
		823	=head1 FORK
		824
		825	Most of the "improved" event delivering mechanisms of modern operating
		826	systems have quite a few problems with fork(2) (to put it bluntly: it is
		827	not supported and usually destructive). Libev makes it possible to work
		828	around this by having a function that recreates the kernel state after
		829	fork in the child.
		830
		831	On non-win32 platforms, this module requires the pthread_atfork
		832	functionality to do this automatically for you. This function is quite
		833	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		834	negligible, because everything the function currently does is set a flag
		835	that is checked only when the event loop gets used the next time, so when
		836	you do fork but not use EV, the overhead is minimal.
		837
		838	On win32, there is no notion of fork so all this doesn't apply, of course.
220		839
221	=cut	840	=cut
222		841
223	our $NPRI = 4;	842	our $DIED = sub {
224	our $BASE;	843	warn "EV: error in callback (ignoring): $@";
225	our $ENABLE_EPOLL;	844	};
226		845
227	{	846	default_loop
228	local $ENV{EVENT_NOEPOLL};	847	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		848
237	1;	849	1;
238		850
239	=head1 SEE ALSO	851	=head1 SEE ALSO
240		852
241	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	853	L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
242	L<EV::AnyEvent>.	854	event loop), L<Coro::EV> (efficient coroutines with EV).
243		855
244	=head1 AUTHOR	856	=head1 AUTHOR
245		857
246	Marc Lehmann <schmorp@schmorp.de>	858	Marc Lehmann <schmorp@schmorp.de>
247	http://home.schmorp.de/	859	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 1.71 by root, Mon Dec 17 07:24:12 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 1.71 by root, Mon Dec 17 07:24:12 2007 UTC