[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 1.73 by root, Fri Dec 21 05:10:01 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 EVENT LOOPS
		94
		95	EV supports multiple event loops: There is a single "default event loop"
		96	that can handle everything including signals and child watchers, and any
		97	number of "dynamic event loops" that can use different backends (with
		98	various limitations), but no child and signal watchers.
		99
		100	You do not have to do anything to create the default event loop: When
		101	the module is loaded a suitable backend is selected on the premise of
		102	selecting a working backend (which for example rules out kqueue on most
		103	BSDs). Modules should, unless they have "special needs" always use the
		104	default loop as this is fastest (perl-wise), best supported by other
		105	modules (e.g. AnyEvent or Coro) and most portable event loop.
		106
		107	For specific programs you cna create additional event loops dynamically.
		108
		109	=over 4
		110
		111	=item $loop = new EV::loop [$flags]
		112
		113	Create a new event loop as per the specified flags. Please refer to the
		114	C<ev_loop_new ()> function description in the libev documentation
		115	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		116	for more info.
		117
		118	The loop will automatically be destroyed when it is no longer referenced
		119	by any watcher and the loop object goes out of scope.
		120
		121	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		122	is protected by this module.
		123
		124	=item $loop->loop_fork
		125
		126	Must be called after a fork in the child, before entering or continuing
		127	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		128	this fucntion automatically, at some performance loss (refer to the libev
		129	documentation).
		130
		131	=back
		132
		133
		134	=head1 BASIC INTERFACE
		135
		136	=over 4
		137
69	=item $EV::NPRI	138	=item $EV::DIED
70		139
71	How many priority levels are available.	140	Must contain a reference to a function that is called when a callback
		141	throws an exception (with $@ containing the error). The default prints an
		142	informative message and continues.
		143
		144	If this callback throws an exception it will be silently ignored.
		145
		146	=item $time = EV::time
		147
		148	Returns the current time in (fractional) seconds since the epoch.
72		149
73	=item $time = EV::now	150	=item $time = EV::now
74		151
75	Returns the time in (fractional) seconds since the epoch.	152	=item $time = $loop->now
76		153
77	=item $version = EV::version	154	Returns the time the last event loop iteration has been started. This
		155	is the time that (relative) timers are based on, and refering to it is
		156	usually faster then calling EV::time.
78		157
79	=item $method = EV::method	158	=item $backend = EV::backend
80		159
81	Return version string and event polling method used.	160	=item $backend = $loop->backend
82		161
83	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	162	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		163	or EV::METHOD_EPOLL).
84		164
85	=item EV::loopexit $after	165	=item EV::loop [$flags]
86		166
87	Exit any active loop or dispatch after C<$after> seconds or immediately if	167	=item $loop->loop ([$flags])
88	C<$after> is missing or zero.
89		168
90	=item EV::dispatch	169	Begin checking for events and calling callbacks. It returns when a
		170	callback calls EV::unloop.
91		171
92	Same as C<EV::loop 0>.	172	The $flags argument can be one of the following:
93		173
94	=item EV::event $callback	174	0 as above
		175	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		176	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
95		177
96	Creates a new event watcher waiting for nothing, calling the given callback.	178	=item EV::unloop [$how]
97		179
		180	=item $loop->unloop ([$how])
		181
		182	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		183	innermost call to EV::loop return.
		184
		185	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		186	fast as possible.
		187
		188	=item $count = EV::loop_count
		189
		190	=item $count = $loop->loop_count
		191
		192	Return the number of times the event loop has polled for new
		193	events. Sometiems useful as a generation counter.
		194
		195	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		196
		197	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		198
		199	This function rolls together an I/O and a timer watcher for a single
		200	one-shot event without the need for managing a watcher object.
		201
		202	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		203	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		204	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		205	you do not want to wait for some I/O event, specify C<undef> for
		206	C<$fh_or_undef> and C<0> for C<$events>).
		207
		208	If timeout is C<undef> or negative, then there will be no
		209	timeout. Otherwise a EV::timer with this value will be started.
		210
		211	When an error occurs or either the timeout or I/O watcher triggers, then
		212	the callback will be called with the received event set (in general
		213	you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
		214	C<EV::WRITE> and C<EV::TIMEOUT>).
		215
		216	EV::once doesn't return anything: the watchers stay active till either
		217	of them triggers, then they will be stopped and freed, and the callback
		218	invoked.
		219
		220	=item EV::feed_fd_event ($fd, $revents)
		221
		222	=item $loop->feed_fd_event ($fd, $revents)
		223
		224	Feed an event on a file descriptor into EV. EV will react to this call as
		225	if the readyness notifications specified by C<$revents> (a combination of
		226	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		227
		228	=item EV::feed_signal_event ($signal)
		229
		230	Feed a signal event into EV. EV will react to this call as if the signal
		231	specified by C<$signal> had occured.
		232
		233	=back
		234
		235
		236	=head1 WATCHER OBJECTS
		237
		238	A watcher is an object that gets created to record your interest in some
		239	event. For instance, if you want to wait for STDIN to become readable, you
		240	would create an EV::io watcher for that:
		241
		242	my $watcher = EV::io *STDIN, EV::READ, sub {
		243	my ($watcher, $revents) = @_;
		244	warn "yeah, STDIN should not be readable without blocking!\n"
		245	};
		246
		247	All watchers can be active (waiting for events) or inactive (paused). Only
		248	active watchers will have their callbacks invoked. All callbacks will be
		249	called with at least two arguments: the watcher and a bitmask of received
		250	events.
		251
		252	Each watcher type has its associated bit in revents, so you can use the
		253	same callback for multiple watchers. The event mask is named after the
		254	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		255	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		256	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		257	uses EV::TIMEOUT).
		258
		259	In the rare case where one wants to create a watcher but not start it at
		260	the same time, each constructor has a variant with a trailing C<_ns> in
		261	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		262
		263	Please note that a watcher will automatically be stopped when the watcher
		264	object is destroyed, so you I<need> to keep the watcher objects returned by
		265	the constructors.
		266
		267	Also, all methods changing some aspect of a watcher (->set, ->priority,
		268	->fh and so on) automatically stop and start it again if it is active,
		269	which means pending events get lost.
		270
		271	=head2 COMMON WATCHER METHODS
		272
		273	This section lists methods common to all watchers.
		274
		275	=over 4
		276
		277	=item $w->start
		278
		279	Starts a watcher if it isn't active already. Does nothing to an already
		280	active watcher. By default, all watchers start out in the active state
		281	(see the description of the C<_ns> variants if you need stopped watchers).
		282
		283	=item $w->stop
		284
		285	Stop a watcher if it is active. Also clear any pending events (events that
		286	have been received but that didn't yet result in a callback invocation),
		287	regardless of whether the watcher was active or not.
		288
		289	=item $bool = $w->is_active
		290
		291	Returns true if the watcher is active, false otherwise.
		292
		293	=item $current_data = $w->data
		294
		295	=item $old_data = $w->data ($new_data)
		296
		297	Queries a freely usable data scalar on the watcher and optionally changes
		298	it. This is a way to associate custom data with a watcher:
		299
		300	my $w = EV::timer 60, 0, sub {
		301	warn $_[0]->data;
		302	};
		303	$w->data ("print me!");
		304
		305	=item $current_cb = $w->cb
		306
		307	=item $old_cb = $w->cb ($new_cb)
		308
		309	Queries the callback on the watcher and optionally changes it. You can do
		310	this at any time without the watcher restarting.
		311
		312	=item $current_priority = $w->priority
		313
		314	=item $old_priority = $w->priority ($new_priority)
		315
		316	Queries the priority on the watcher and optionally changes it. Pending
		317	watchers with higher priority will be invoked first. The valid range of
		318	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		319	-2). If the priority is outside this range it will automatically be
		320	normalised to the nearest valid priority.
		321
		322	The default priority of any newly-created watcher is 0.
		323
		324	Note that the priority semantics have not yet been fleshed out and are
		325	subject to almost certain change.
		326
		327	=item $w->invoke ($revents)
		328
		329	Call the callback now with the given event mask.
		330
		331	=item $w->feed_event ($revents)
		332
		333	Feed some events on this watcher into EV. EV will react to this call as if
		334	the watcher had received the given C<$revents> mask.
		335
		336	=item $revents = $w->clear_pending
		337
		338	If the watcher is pending, this function returns clears its pending status
		339	and returns its C<$revents> bitset (as if its callback was invoked). If the
		340	watcher isn't pending it does nothing and returns C<0>.
		341
		342	=item $previous_state = $w->keepalive ($bool)
		343
		344	Normally, C<EV::loop> will return when there are no active watchers
		345	(which is a "deadlock" because no progress can be made anymore). This is
		346	convinient because it allows you to start your watchers (and your jobs),
		347	call C<EV::loop> once and when it returns you know that all your jobs are
		348	finished (or they forgot to register some watchers for their task :).
		349
		350	Sometimes, however, this gets in your way, for example when you the module
		351	that calls C<EV::loop> (usually the main program) is not the same module
		352	as a long-living watcher (for example a DNS client module written by
		353	somebody else even). Then you might want any outstanding requests to be
		354	handled, but you would not want to keep C<EV::loop> from returning just
		355	because you happen to have this long-running UDP port watcher.
		356
		357	In this case you can clear the keepalive status, which means that even
		358	though your watcher is active, it won't keep C<EV::loop> from returning.
		359
		360	The initial value for keepalive is true (enabled), and you cna change it
		361	any time.
		362
		363	Example: Register an I/O watcher for some UDP socket but do not keep the
		364	event loop from running just because of that watcher.
		365
		366	my $udp_socket = ...
		367	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		368	$udp_watcher->keepalive (0);
		369
		370	=back
		371
		372
		373	=head1 WATCHER TYPES
		374
		375	Each of the following subsections describes a single watcher type.
		376
		377	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		378
		379	=over 4
		380
98	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	381	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
99		382
100	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	383	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		384
		385	=item $w = $loop->io 8$fileno_or_fh, $eventmask, $callback)
		386
		387	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
101		388
102	As long as the returned watcher object is alive, call the C<$callback>	389	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	390	when at least one of events specified in C<$eventmask> occurs.
104	is disabled.
105		391
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:	392	The $eventmask can be one or more of these constants ORed together:
109		393
110	EV::READ wait until read() wouldn't block anymore	394	EV::READ wait until read() wouldn't block anymore
111	EV::WRITE wait until write() wouldn't block anymore	395	EV::WRITE wait until write() wouldn't block anymore
112	EV::PERSIST stay active after an event occured
113		396
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.	397	The C<io_ns> variant doesn't start (activate) the newly created watcher.
124		398
125	=item my $w = EV::timer_abs $at, $interval, $callback	399	=item $w->set ($fileno_or_fh, $eventmask)
126		400
127	=item my $w = EV::timer_abs_ns $at, $interval, $callback	401	Reconfigures the watcher, see the constructor above for details. Can be
128		402	called at any time.
129	Similar to EV::timer, but the time is given as an absolute point in time
130	(C<$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		403
183	=item $current_fh = $w->fh	404	=item $current_fh = $w->fh
184		405
185	=item $old_fh = $w->fh ($new_fh)	406	=item $old_fh = $w->fh ($new_fh)
186		407
190		411
191	=item $old_eventmask = $w->events ($new_eventmask)	412	=item $old_eventmask = $w->events ($new_eventmask)
192		413
193	Returns the previously set event mask and optionally set a new one.	414	Returns the previously set event mask and optionally set a new one.
194		415
		416	=back
		417
		418
		419	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		420
		421	=over 4
		422
		423	=item $w = EV::timer $after, $repeat, $callback
		424
		425	=item $w = EV::timer_ns $after, $repeat, $callback
		426
		427	=item $w = $loop->timer ($after, $repeat, $callback)
		428
		429	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		430
		431	Calls the callback after C<$after> seconds (which may be fractional). If
		432	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		433	value as $after) after the callback returns.
		434
		435	This means that the callback would be called roughly after C<$after>
		436	seconds, and then every C<$repeat> seconds. The timer does his best not
		437	to drift, but it will not invoke the timer more often then once per event
		438	loop iteration, and might drift in other cases. If that isn't acceptable,
		439	look at EV::periodic, which can provide long-term stable timers.
		440
		441	The timer is based on a monotonic clock, that is, if somebody is sitting
		442	in front of the machine while the timer is running and changes the system
		443	clock, the timer will nevertheless run (roughly) the same time.
		444
		445	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
		446
195	=item $w->timeout ($after, $repeat)	447	=item $w->set ($after, $repeat)
196		448
197	Resets the timeout (see C<EV::timer> for details).	449	Reconfigures the watcher, see the constructor above for details. Can be called at
		450	any time.
198		451
199	=item $w->timeout_abs ($at, $interval)	452	=item $w->again
200		453
201	Resets the timeout (see C<EV::timer_abs> for details).	454	Similar to the C<start> method, but has special semantics for repeating timers:
202		455
203	=item $w->priority_set ($priority)	456	If the timer is active and non-repeating, it will be stopped.
204		457
205	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	458	If the timer is active and repeating, reset the timeout to occur
		459	C<$repeat> seconds after now.
206		460
207	=back	461	If the timer is inactive and repeating, start it using the repeat value.
208		462
209	=head1 BUGS	463	Otherwise do nothing.
210		464
211	Lots. Libevent itself isn't well tested and rather buggy, and this module	465	This behaviour is useful when you have a timeout for some IO
212	is quite new at the moment.	466	operation. You create a timer object with the same value for C<$after> and
		467	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		468	on the timeout.
213		469
214	Please note that the epoll method is not, in general, reliable in	470	=back
215	programs that use fork (even if no libveent calls are being made in the	471
216	forked process). Since this is such a common issue, this module will	472
217	force the epoll method in EV to be off unless the global variable	473	=head3 PERIODIC WATCHERS - to cron or not to cron?
218	$EV::ENABLE_EPOLL is set to 1 before loading this module for the first	474
		475	=over 4
		476
		477	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		478
		479	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		480
		481	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		482
		483	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		484
		485	Similar to EV::timer, but is not based on relative timeouts but on
		486	absolute times. Apart from creating "simple" timers that trigger "at" the
		487	specified time, it can also be used for non-drifting absolute timers and
		488	more complex, cron-like, setups that are not adversely affected by time
		489	jumps (i.e. when the system clock is changed by explicit date -s or other
		490	means such as ntpd). It is also the most complex watcher type in EV.
		491
		492	It has three distinct "modes":
		493
		494	=over 4
		495
		496	=item * absolute timer ($interval = $reschedule_cb = 0)
		497
		498	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		499	will not adjust when a time jump occurs, that is, if it is to be run
		500	at January 1st 2011 then it will run when the system time reaches or
		501	surpasses this time.
		502
		503	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		504
		505	In this mode the watcher will always be scheduled to time out at the
		506	next C<$at + N * $interval> time (for some integer N) and then repeat,
		507	regardless of any time jumps.
		508
		509	This can be used to create timers that do not drift with respect to system
219	time.	510	time:
		511
		512	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		513
		514	That doesn't mean there will always be 3600 seconds in between triggers,
		515	but only that the the clalback will be called when the system time shows a
		516	full hour (UTC).
		517
		518	Another way to think about it (for the mathematically inclined) is that
		519	EV::periodic will try to run the callback in this mode at the next
		520	possible time where C<$time = $at (mod $interval)>, regardless of any time
		521	jumps.
		522
		523	=item * manual reschedule mode ($reschedule_cb = coderef)
		524
		525	In this mode $interval and $at are both being ignored. Instead, each
		526	time the periodic watcher gets scheduled, the reschedule callback
		527	($reschedule_cb) will be called with the watcher as first, and the current
		528	time as second argument.
		529
		530	I<This callback MUST NOT stop or destroy this or any other periodic
		531	watcher, ever>. If you need to stop it, return 1e30 and stop it
		532	afterwards.
		533
		534	It must return the next time to trigger, based on the passed time value
		535	(that is, the lowest time value larger than to the second argument). It
		536	will usually be called just before the callback will be triggered, but
		537	might be called at other times, too.
		538
		539	This can be used to create very complex timers, such as a timer that
		540	triggers on each midnight, local time (actually 24 hours after the last
		541	midnight, to keep the example simple. If you know a way to do it correctly
		542	in about the same space (without requiring elaborate modules), drop me a
		543	note :):
		544
		545	my $daily = EV::periodic 0, 0, sub {
		546	my ($w, $now) = @_;
		547
		548	use Time::Local ();
		549	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		550	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		551	}, sub {
		552	print "it's midnight or likely shortly after, now\n";
		553	};
		554
		555	=back
		556
		557	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
		558
		559	=item $w->set ($at, $interval, $reschedule_cb)
		560
		561	Reconfigures the watcher, see the constructor above for details. Can be called at
		562	any time.
		563
		564	=item $w->again
		565
		566	Simply stops and starts the watcher again.
		567
		568	=item $time = $w->at
		569
		570	Return the time that the watcher is expected to trigger next.
		571
		572	=back
		573
		574
		575	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		576
		577	=over 4
		578
		579	=item $w = EV::signal $signal, $callback
		580
		581	=item $w = EV::signal_ns $signal, $callback
		582
		583	Call the callback when $signal is received (the signal can be specified by
		584	number or by name, just as with C<kill> or C<%SIG>).
		585
		586	EV will grab the signal for the process (the kernel only allows one
		587	component to receive a signal at a time) when you start a signal watcher,
		588	and removes it again when you stop it. Perl does the same when you
		589	add/remove callbacks to C<%SIG>, so watch out.
		590
		591	You can have as many signal watchers per signal as you want.
		592
		593	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
		594
		595	=item $w->set ($signal)
		596
		597	Reconfigures the watcher, see the constructor above for details. Can be
		598	called at any time.
		599
		600	=item $current_signum = $w->signal
		601
		602	=item $old_signum = $w->signal ($new_signal)
		603
		604	Returns the previously set signal (always as a number not name) and
		605	optionally set a new one.
		606
		607	=back
		608
		609
		610	=head3 CHILD WATCHERS - watch out for process status changes
		611
		612	=over 4
		613
		614	=item $w = EV::child $pid, $callback
		615
		616	=item $w = EV::child_ns $pid, $callback
		617
		618	=item $w = $loop->child ($pid, $callback)
		619
		620	=item $w = $loop->child_ns ($pid, $callback)
		621
		622	Call the callback when a status change for pid C<$pid> (or any pid if
		623	C<$pid> is 0) has been received. More precisely: when the process receives
		624	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		625	changed/zombie children and call the callback.
		626
		627	It is valid (and fully supported) to install a child watcher after a child
		628	has exited but before the event loop has started its next iteration (for
		629	example, first you C<fork>, then the new child process might exit, and
		630	only then do you install a child watcher in the parent for the new pid).
		631
		632	You can access both exit (or tracing) status and pid by using the
		633	C<rstatus> and C<rpid> methods on the watcher object.
		634
		635	You can have as many pid watchers per pid as you want, they will all be
		636	called.
		637
		638	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		639
		640	=item $w->set ($pid)
		641
		642	Reconfigures the watcher, see the constructor above for details. Can be called at
		643	any time.
		644
		645	=item $current_pid = $w->pid
		646
		647	=item $old_pid = $w->pid ($new_pid)
		648
		649	Returns the previously set process id and optionally set a new one.
		650
		651	=item $exit_status = $w->rstatus
		652
		653	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		654	in perlfunc).
		655
		656	=item $pid = $w->rpid
		657
		658	Return the pid of the awaited child (useful when you have installed a
		659	watcher for all pids).
		660
		661	=back
		662
		663
		664	=head3 STAT WATCHERS - did the file attributes just change?
		665
		666	=over 4
		667
		668	=item $w = EV::stat $path, $interval, $callback
		669
		670	=item $w = EV::stat_ns $path, $interval, $callback
		671
		672	=item $w = $loop->stat ($path, $interval, $callback)
		673
		674	=item $w = $loop->stat_ns ($path, $interval, $callback)
		675
		676	Call the callback when a file status change has been detected on
		677	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		678	to "path does not exist" is a status change like any other.
		679
		680	The C<$interval> is a recommended polling interval for systems where
		681	OS-supported change notifications don't exist or are not supported. If
		682	you use C<0> then an unspecified default is used (which is highly
		683	recommended!), which is to be expected to be around five seconds usually.
		684
		685	This watcher type is not meant for massive numbers of stat watchers,
		686	as even with OS-supported change notifications, this can be
		687	resource-intensive.
		688
		689	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		690
		691	=item ... = $w->stat
		692
		693	This call is very similar to the perl C<stat> built-in: It stats (using
		694	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		695	well as EV's idea of the current stat values) to the values found.
		696
		697	In scalar context, a boolean is return indicating success or failure of
		698	the stat. In list context, the same 13-value list as with stat is returned
		699	(except that the blksize and blocks fields are not reliable).
		700
		701	In the case of an error, errno is set to C<ENOENT> (regardless of the
		702	actual error value) and the C<nlink> value is forced to zero (if the stat
		703	was successful then nlink is guaranteed to be non-zero).
		704
		705	See also the next two entries for more info.
		706
		707	=item ... = $w->attr
		708
		709	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		710	the values most recently detected by EV. See the next entry for more info.
		711
		712	=item ... = $w->prev
		713
		714	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		715	the previous set of values, before the change.
		716
		717	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		718	to the values found I<before> a change was detected, while C<< $w->attr >>
		719	returns the values found leading to the change detection. The difference (if any)
		720	between C<prev> and C<attr> is what triggered the callback.
		721
		722	If you did something to the filesystem object and do not want to trigger
		723	yet another change, you can call C<stat> to update EV's idea of what the
		724	current attributes are.
		725
		726	=item $w->set ($path, $interval)
		727
		728	Reconfigures the watcher, see the constructor above for details. Can be
		729	called at any time.
		730
		731	=item $current_path = $w->path
		732
		733	=item $old_path = $w->path ($new_path)
		734
		735	Returns the previously set path and optionally set a new one.
		736
		737	=item $current_interval = $w->interval
		738
		739	=item $old_interval = $w->interval ($new_interval)
		740
		741	Returns the previously set interval and optionally set a new one. Can be
		742	used to query the actual interval used.
		743
		744	=back
		745
		746
		747	=head3 IDLE WATCHERS - when you've got nothing better to do...
		748
		749	=over 4
		750
		751	=item $w = EV::idle $callback
		752
		753	=item $w = EV::idle_ns $callback
		754
		755	=item $w = $loop->idle ($callback)
		756
		757	=item $w = $loop->idle_ns ($callback)
		758
		759	Call the callback when there are no other pending watchers of the same or
		760	higher priority (excluding check, prepare and other idle watchers of the
		761	same or lower priority, of course). They are called idle watchers because
		762	when the watcher is the highest priority pending event in the process, the
		763	process is considered to be idle at that priority.
		764
		765	If you want a watcher that is only ever called when I<no> other events are
		766	outstanding you have to set the priority to C<EV::MINPRI>.
		767
		768	The process will not block as long as any idle watchers are active, and
		769	they will be called repeatedly until stopped.
		770
		771	For example, if you have idle watchers at priority C<0> and C<1>, and
		772	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		773	and the I/O watcher will always run when ready. Only when the idle watcher
		774	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		775	pending with the C<0>-priority idle watcher be invoked.
		776
		777	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		778
		779	=back
		780
		781
		782	=head3 PREPARE WATCHERS - customise your event loop!
		783
		784	=over 4
		785
		786	=item $w = EV::prepare $callback
		787
		788	=item $w = EV::prepare_ns $callback
		789
		790	=item $w = $loop->prepare ($callback)
		791
		792	=item $w = $loop->prepare_ns 8$callback)
		793
		794	Call the callback just before the process would block. You can still
		795	create/modify any watchers at this point.
		796
		797	See the EV::check watcher, below, for explanations and an example.
		798
		799	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		800
		801	=back
		802
		803
		804	=head3 CHECK WATCHERS - customise your event loop even more!
		805
		806	=over 4
		807
		808	=item $w = EV::check $callback
		809
		810	=item $w = EV::check_ns $callback
		811
		812	=item $w = $loop->check ($callback)
		813
		814	=item $w = $loop->check_ns ($callback)
		815
		816	Call the callback just after the process wakes up again (after it has
		817	gathered events), but before any other callbacks have been invoked.
		818
		819	This is used to integrate other event-based software into the EV
		820	mainloop: You register a prepare callback and in there, you create io and
		821	timer watchers as required by the other software. Here is a real-world
		822	example of integrating Net::SNMP (with some details left out):
		823
		824	our @snmp_watcher;
		825
		826	our $snmp_prepare = EV::prepare sub {
		827	# do nothing unless active
		828	$dispatcher->{_event_queue_h}
		829	or return;
		830
		831	# make the dispatcher handle any outstanding stuff
		832	... not shown
		833
		834	# create an I/O watcher for each and every socket
		835	@snmp_watcher = (
		836	(map { EV::io $_, EV::READ, sub { } }
		837	keys %{ $dispatcher->{_descriptors} }),
		838
		839	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		840	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		841	0, sub { },
		842	);
		843	};
		844
		845	The callbacks are irrelevant (and are not even being called), the
		846	only purpose of those watchers is to wake up the process as soon as
		847	one of those events occurs (socket readable, or timer timed out). The
		848	corresponding EV::check watcher will then clean up:
		849
		850	our $snmp_check = EV::check sub {
		851	# destroy all watchers
		852	@snmp_watcher = ();
		853
		854	# make the dispatcher handle any new stuff
		855	... not shown
		856	};
		857
		858	The callbacks of the created watchers will not be called as the watchers
		859	are destroyed before this cna happen (remember EV::check gets called
		860	first).
		861
		862	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		863
		864	=back
		865
		866
		867	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		868
		869	Fork watchers are called when a C<fork ()> was detected. The invocation
		870	is done before the event loop blocks next and before C<check> watchers
		871	are being called, and only in the child after the fork.
		872
		873	=over 4
		874
		875	=item $w = EV::fork $callback
		876
		877	=item $w = EV::fork_ns $callback
		878
		879	=item $w = $loop->fork ($callback)
		880
		881	=item $w = $loop->fork_ns ($callback)
		882
		883	Call the callback before the event loop is resumed in the child process
		884	after a fork.
		885
		886	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		887
		888	=back
		889
		890
		891	=head1 PERL SIGNALS
		892
		893	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		894	with EV is as the same as any other C library: Perl-signals will only be
		895	handled when Perl runs, which means your signal handler might be invoked
		896	only the next time an event callback is invoked.
		897
		898	The solution is to use EV signal watchers (see C<EV::signal>), which will
		899	ensure proper operations with regards to other event watchers.
		900
		901	If you cannot do this for whatever reason, you can also force a watcher
		902	to be called on every event loop iteration by installing a C<EV::check>
		903	watcher:
		904
		905	my $async_check = EV::check sub { };
		906
		907	This ensures that perl shortly gets into control for a short time, and
		908	also ensures slower overall operation.
		909
		910	=head1 THREADS
		911
		912	Threads are not supported by this module in any way. Perl pseudo-threads
		913	is evil stuff and must die. As soon as Perl gains real threads I will work
		914	on thread support for it.
		915
		916	=head1 FORK
		917
		918	Most of the "improved" event delivering mechanisms of modern operating
		919	systems have quite a few problems with fork(2) (to put it bluntly: it is
		920	not supported and usually destructive). Libev makes it possible to work
		921	around this by having a function that recreates the kernel state after
		922	fork in the child.
		923
		924	On non-win32 platforms, this module requires the pthread_atfork
		925	functionality to do this automatically for you. This function is quite
		926	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		927	negligible, because everything the function currently does is set a flag
		928	that is checked only when the event loop gets used the next time, so when
		929	you do fork but not use EV, the overhead is minimal.
		930
		931	On win32, there is no notion of fork so all this doesn't apply, of course.
220		932
221	=cut	933	=cut
222		934
223	our $NPRI = 4;	935	our $DIED = sub {
224	our $BASE;	936	warn "EV: error in callback (ignoring): $@";
225	our $ENABLE_EPOLL;	937	};
226		938
227	{	939	default_loop
228	local $ENV{EVENT_NOEPOLL};	940	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		941
237	1;	942	1;
238		943
239	=head1 SEE ALSO	944	=head1 SEE ALSO
240		945
241	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	946	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
242	L<EV::AnyEvent>.	947	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		948	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP).
243		949
244	=head1 AUTHOR	950	=head1 AUTHOR
245		951
246	Marc Lehmann <schmorp@schmorp.de>	952	Marc Lehmann <schmorp@schmorp.de>
247	http://home.schmorp.de/	953	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 1.73 by root, Fri Dec 21 05:10:01 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 1.73 by root, Fri Dec 21 05:10:01 2007 UTC