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

Comparing EV/EV.pm (file contents):
Revision 1.24 by root, Fri Nov 2 22:03:00 2007 UTC vs.
Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC

…		…
2		2
3	EV - perl interface to libev, a high performance full-featured event loop	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
		9	# TIMERS
		10
		11	my $w = EV::timer 2, 0, sub {
		12	warn "is called after 2s";
		13	};
		14
		15	my $w = EV::timer 2, 2, sub {
		16	warn "is called roughly every 2s (repeat = 2)";
		17	};
		18
		19	undef $w; # destroy event watcher again
		20
		21	my $w = EV::periodic 0, 60, 0, sub {
		22	warn "is called every minute, on the minute, exactly";
		23	};
		24
		25	# IO
		26
		27	my $w = EV::io *STDIN, EV::READ, sub {
		28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
		29	warn "stdin is readable, you entered: ", <STDIN>;
		30	};
		31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
8		39
9	# TIMERS	40	my $w = EV::child 666, 0, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
10		44
11	my $w = EV::timer 2, 0, sub {	45	# STAT CHANGES
12	warn "is called after 2s";	46	my $w = EV::stat "/etc/passwd", 10, sub {
		47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
13	};	49	};
14		50
15	my $w = EV::timer 2, 1, sub {
16	warn "is called roughly every 2s (repeat = 1)";
17	};
18
19	undef $w; # destroy event watcher again
20
21	my $w = EV::periodic 0, 60, sub {
22	warn "is called every minute, on the minute, exactly";
23	};
24
25	# IO
26
27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
29	warn "stdin is readable, you entered: ", <STDIN>;
30	};
31
32	# SIGNALS
33
34	my $w = EV::signal 'QUIT', sub {
35	warn "sigquit received\n";
36	};
37
38	my $w = EV::signal 3, sub {
39	warn "sigquit received (this is GNU/Linux, right?)\n";
40	};
41
42	# CHILD/PID STATUS CHANGES
43
44	my $w = EV::child 666, sub {
45	my ($w, $revents, $status) = @_;
46	};
47
48	# MAINLOOP	51	# MAINLOOP
49	EV::loop; # loop until EV::loop_done is called	52	EV::loop; # loop until EV::unloop is called or all watchers stop
50	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
51	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
52		55
53	=head1 DESCRIPTION	56	=head1 DESCRIPTION
54		57
55	This module provides an interface to libev	58	This module provides an interface to libev
56	(L<http://software.schmorp.de/pkg/libev.html>).	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		60	below is comprehensive, one might also consult the documentation of
		61	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		62	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		63	discussion on the available backends, or how to force a specific backend
		64	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		65	detailed information.
		66
		67	This module is very fast and scalable. It is actually so fast that you
		68	can use it through the L<AnyEvent> module, stay portable to other event
		69	loops (if you don't rely on any watcher types not available through it)
		70	and still be faster than with any other event loop currently supported in
		71	Perl.
		72
		73	=head2 MODULE EXPORTS
		74
		75	This module does not export any symbols.
57		76
58	=cut	77	=cut
59		78
60	package EV;	79	package EV;
61		80
62	use strict;	81	use common::sense;
63		82
64	BEGIN {	83	BEGIN {
65	our $VERSION = '0.1';	84	our $VERSION = '3.6';
66	use XSLoader;	85	use XSLoader;
67	XSLoader::load "EV", $VERSION;	86	XSLoader::load "EV", $VERSION;
68	}	87	}
69		88
70	@EV::Io::ISA =	89	@EV::IO::ISA =
71	@EV::Timer::ISA =	90	@EV::Timer::ISA =
72	@EV::Periodic::ISA =	91	@EV::Periodic::ISA =
73	@EV::Signal::ISA =	92	@EV::Signal::ISA =
		93	@EV::Child::ISA =
		94	@EV::Stat::ISA =
74	@EV::Idle::ISA =	95	@EV::Idle::ISA =
75	@EV::Prepare::ISA =	96	@EV::Prepare::ISA =
76	@EV::Check::ISA =	97	@EV::Check::ISA =
77	@EV::Child::ISA = "EV::Watcher";	98	@EV::Embed::ISA =
		99	@EV::Fork::ISA =
		100	@EV::Async::ISA =
		101	"EV::Watcher";
		102
		103	@EV::Loop::Default::ISA = "EV::Loop";
		104
		105	=head1 EVENT LOOPS
		106
		107	EV supports multiple event loops: There is a single "default event loop"
		108	that can handle everything including signals and child watchers, and any
		109	number of "dynamic event loops" that can use different backends (with
		110	various limitations), but no child and signal watchers.
		111
		112	You do not have to do anything to create the default event loop: When
		113	the module is loaded a suitable backend is selected on the premise of
		114	selecting a working backend (which for example rules out kqueue on most
		115	BSDs). Modules should, unless they have "special needs" always use the
		116	default loop as this is fastest (perl-wise), best supported by other
		117	modules (e.g. AnyEvent or Coro) and most portable event loop.
		118
		119	For specific programs you can create additional event loops dynamically.
		120
		121	If you want to take advantage of kqueue (which often works properly for
		122	sockets only) even though the default loop doesn't enable it, you can
		123	I<embed> a kqueue loop into the default loop: running the default loop
		124	will then also service the kqueue loop to some extent. See the example in
		125	the section about embed watchers for an example on how to achieve that.
		126
		127	=over 4
		128
		129	=item $loop = new EV::Loop [$flags]
		130
		131	Create a new event loop as per the specified flags. Please refer to
		132	the C<ev_loop_new ()> function description in the libev documentation
		133	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		134	or locally-installed as F<EV::libev> manpage) for more info.
		135
		136	The loop will automatically be destroyed when it is no longer referenced
		137	by any watcher and the loop object goes out of scope.
		138
		139	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		140	is recommended, as only the default event loop is protected by this
		141	module. If you I<are> embedding this loop in the default loop, this is not
		142	necessary, as C<EV::embed> automatically does the right thing on fork.
		143
		144	=item $loop->loop_fork
		145
		146	Must be called after a fork in the child, before entering or continuing
		147	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		148	this function automatically, at some performance loss (refer to the libev
		149	documentation).
		150
		151	=item $loop->loop_verify
		152
		153	Calls C<ev_verify> to make internal consistency checks (for debugging
		154	libev) and abort the program if any data structures were found to be
		155	corrupted.
		156
		157	=item $loop = EV::default_loop [$flags]
		158
		159	Return the default loop (which is a singleton object). Since this module
		160	already creates the default loop with default flags, specifying flags here
		161	will not have any effect unless you destroy the default loop first, which
		162	isn't supported. So in short: don't do it, and if you break it, you get to
		163	keep the pieces.
		164
		165	=back
		166
78		167
79	=head1 BASIC INTERFACE	168	=head1 BASIC INTERFACE
80		169
81	=over 4	170	=over 4
82		171
83	=item $EV::DIED	172	=item $EV::DIED
84		173
85	Must contain a reference to a function that is called when a callback	174	Must contain a reference to a function that is called when a callback
86	throws an exception (with $@ containing thr error). The default prints an	175	throws an exception (with $@ containing the error). The default prints an
87	informative message and continues.	176	informative message and continues.
88		177
89	If this callback throws an exception it will be silently ignored.	178	If this callback throws an exception it will be silently ignored.
90		179
		180	=item $flags = EV::supported_backends
		181
		182	=item $flags = EV::recommended_backends
		183
		184	=item $flags = EV::embeddable_backends
		185
		186	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		187	instance of EV, the set of recommended backends (supposed to be good) for
		188	this platform and the set of embeddable backends (see EMBED WATCHERS).
		189
		190	=item EV::sleep $seconds
		191
		192	Block the process for the given number of (fractional) seconds.
		193
91	=item $time = EV::time	194	=item $time = EV::time
92		195
93	Returns the current time in (fractional) seconds since the epoch.	196	Returns the current time in (fractional) seconds since the epoch.
94		197
95	=item $time = EV::now	198	=item $time = EV::now
96		199
		200	=item $time = $loop->now
		201
97	Returns the time the last event loop iteration has been started. This	202	Returns the time the last event loop iteration has been started. This
98	is the time that (relative) timers are based on, and refering to it is	203	is the time that (relative) timers are based on, and referring to it is
99	usually faster then calling EV::time.	204	usually faster then calling EV::time.
100		205
101	=item $method = EV::ev_method	206	=item EV::now_update
102		207
		208	=item $loop->now_update
		209
		210	Establishes the current time by querying the kernel, updating the time
		211	returned by C<EV::now> in the progress. This is a costly operation and
		212	is usually done automatically within C<EV::loop>.
		213
		214	This function is rarely useful, but when some event callback runs for a
		215	very long time without entering the event loop, updating libev's idea of
		216	the current time is a good idea.
		217
		218	=item EV::suspend
		219
		220	=item $loop->suspend
		221
		222	=item EV::resume
		223
		224	=item $loop->resume
		225
		226	These two functions suspend and resume a loop, for use when the loop is
		227	not used for a while and timeouts should not be processed.
		228
		229	A typical use case would be an interactive program such as a game: When
		230	the user presses C<^Z> to suspend the game and resumes it an hour later it
		231	would be best to handle timeouts as if no time had actually passed while
		232	the program was suspended. This can be achieved by calling C<suspend>
		233	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		234	C<resume> directly afterwards to resume timer processing.
		235
		236	Effectively, all C<timer> watchers will be delayed by the time spend
		237	between C<suspend> and C<resume>, and all C<periodic> watchers
		238	will be rescheduled (that is, they will lose any events that would have
		239	occured while suspended).
		240
		241	After calling C<suspend> you B<must not> call I<any> function on the given
		242	loop other than C<resume>, and you B<must not> call C<resume>
		243	without a previous call to C<suspend>.
		244
		245	Calling C<suspend>/C<resume> has the side effect of updating the event
		246	loop time (see C<now_update>).
		247
		248	=item $backend = EV::backend
		249
		250	=item $backend = $loop->backend
		251
103	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	252	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
104	or EV::METHOD_EPOLL).	253	or EV::BACKEND_EPOLL).
105		254
106	=item EV::loop [$flags]	255	=item EV::loop [$flags]
107		256
		257	=item $loop->loop ([$flags])
		258
108	Begin checking for events and calling callbacks. It returns when a	259	Begin checking for events and calling callbacks. It returns when a
109	callback calls EV::loop_done.	260	callback calls EV::unloop.
110		261
111	The $flags argument can be one of the following:	262	The $flags argument can be one of the following:
112		263
113	0 as above	264	0 as above
114	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	265	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
115	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	266	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
116		267
117	=item EV::loop_done [$how]	268	=item EV::unloop [$how]
118		269
		270	=item $loop->unloop ([$how])
		271
119	When called with no arguments or an argument of 1, makes the innermost	272	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
120	call to EV::loop return.	273	innermost call to EV::loop return.
121		274
122	When called with an agrument of 2, all calls to EV::loop will return as	275	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
123	fast as possible.	276	fast as possible.
124		277
125	=back	278	=item $count = EV::loop_count
126		279
127	=head2 WATCHER	280	=item $count = $loop->loop_count
		281
		282	Return the number of times the event loop has polled for new
		283	events. Sometimes useful as a generation counter.
		284
		285	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		286
		287	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		288
		289	This function rolls together an I/O and a timer watcher for a single
		290	one-shot event without the need for managing a watcher object.
		291
		292	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		293	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		294	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		295	you do not want to wait for some I/O event, specify C<undef> for
		296	C<$fh_or_undef> and C<0> for C<$events>).
		297
		298	If timeout is C<undef> or negative, then there will be no
		299	timeout. Otherwise a EV::timer with this value will be started.
		300
		301	When an error occurs or either the timeout or I/O watcher triggers, then
		302	the callback will be called with the received event set (in general
		303	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		304	C<EV::WRITE> and C<EV::TIMEOUT>).
		305
		306	EV::once doesn't return anything: the watchers stay active till either
		307	of them triggers, then they will be stopped and freed, and the callback
		308	invoked.
		309
		310	=item EV::feed_fd_event ($fd, $revents)
		311
		312	=item $loop->feed_fd_event ($fd, $revents)
		313
		314	Feed an event on a file descriptor into EV. EV will react to this call as
		315	if the readyness notifications specified by C<$revents> (a combination of
		316	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		317
		318	=item EV::feed_signal_event ($signal)
		319
		320	Feed a signal event into EV. EV will react to this call as if the signal
		321	specified by C<$signal> had occured.
		322
		323	=item EV::set_io_collect_interval $time
		324
		325	=item $loop->set_io_collect_interval ($time)
		326
		327	=item EV::set_timeout_collect_interval $time
		328
		329	=item $loop->set_timeout_collect_interval ($time)
		330
		331	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		332	wait interval for timer events. See the libev documentation at
		333	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		334	(locally installed as F<EV::libev>) for a more detailed discussion.
		335
		336	=back
		337
		338
		339	=head1 WATCHER OBJECTS
128		340
129	A watcher is an object that gets created to record your interest in some	341	A watcher is an object that gets created to record your interest in some
130	event. For instance, if you want to wait for STDIN to become readable, you	342	event. For instance, if you want to wait for STDIN to become readable, you
131	would create an EV::io watcher for that:	343	would create an EV::io watcher for that:
132		344
133	my $watcher = EV::io *STDIN, EV::READ, sub {	345	my $watcher = EV::io *STDIN, EV::READ, sub {
134	my ($watcher, $revents) = @_;	346	my ($watcher, $revents) = @_;
135	warn "yeah, STDIN should not be readable without blocking!\n"	347	warn "yeah, STDIN should now be readable without blocking!\n"
136	};	348	};
137		349
138	All watchers can be active (waiting for events) or inactive (paused). Only	350	All watchers can be active (waiting for events) or inactive (paused). Only
139	active watchers will have their callbacks invoked. All callbacks will be	351	active watchers will have their callbacks invoked. All callbacks will be
140	called with at least two arguments: the watcher and a bitmask of received	352	called with at least two arguments: the watcher and a bitmask of received
141	events.	353	events.
142		354
143	Each watcher type has its associated bit in revents, so you can use the	355	Each watcher type has its associated bit in revents, so you can use the
144	same callback for multiple watchers. The event mask is named after the	356	same callback for multiple watchers. The event mask is named after the
145	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,	357	type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
146	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events	358	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
147	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which	359	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
148	uses EV::TIMEOUT).	360	uses EV::TIMEOUT).
149		361
150	In the rare case where one wants to create a watcher but not start it at	362	In the rare case where one wants to create a watcher but not start it at
151	the same time, each constructor has a variant with a trailing C<_ns> in	363	the same time, each constructor has a variant with a trailing C<_ns> in
…		…
157		369
158	Also, all methods changing some aspect of a watcher (->set, ->priority,	370	Also, all methods changing some aspect of a watcher (->set, ->priority,
159	->fh and so on) automatically stop and start it again if it is active,	371	->fh and so on) automatically stop and start it again if it is active,
160	which means pending events get lost.	372	which means pending events get lost.
161		373
162	=head2 WATCHER TYPES	374	=head2 COMMON WATCHER METHODS
163		375
164	Now lets move to the existing watcher types and asociated methods.	376	This section lists methods common to all watchers.
165
166	The following methods are available for all watchers. Then followes a
167	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
168	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
169	any type-specific methods (if any).
170		377
171	=over 4	378	=over 4
172		379
173	=item $w->start	380	=item $w->start
174		381
…		…
178		385
179	=item $w->stop	386	=item $w->stop
180		387
181	Stop a watcher if it is active. Also clear any pending events (events that	388	Stop a watcher if it is active. Also clear any pending events (events that
182	have been received but that didn't yet result in a callback invocation),	389	have been received but that didn't yet result in a callback invocation),
183	regardless of wether the watcher was active or not.	390	regardless of whether the watcher was active or not.
184		391
185	=item $bool = $w->is_active	392	=item $bool = $w->is_active
186		393
187	Returns true if the watcher is active, false otherwise.	394	Returns true if the watcher is active, false otherwise.
		395
		396	=item $current_data = $w->data
		397
		398	=item $old_data = $w->data ($new_data)
		399
		400	Queries a freely usable data scalar on the watcher and optionally changes
		401	it. This is a way to associate custom data with a watcher:
		402
		403	my $w = EV::timer 60, 0, sub {
		404	warn $_[0]->data;
		405	};
		406	$w->data ("print me!");
188		407
189	=item $current_cb = $w->cb	408	=item $current_cb = $w->cb
190		409
191	=item $old_cb = $w->cb ($new_cb)	410	=item $old_cb = $w->cb ($new_cb)
192		411
…		…
201	watchers with higher priority will be invoked first. The valid range of	420	watchers with higher priority will be invoked first. The valid range of
202	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default	421	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
203	-2). If the priority is outside this range it will automatically be	422	-2). If the priority is outside this range it will automatically be
204	normalised to the nearest valid priority.	423	normalised to the nearest valid priority.
205		424
206	The default priority of any newly-created weatcher is 0.	425	The default priority of any newly-created watcher is 0.
207		426
		427	Note that the priority semantics have not yet been fleshed out and are
		428	subject to almost certain change.
		429
208	=item $w->trigger ($revents)	430	=item $w->invoke ($revents)
209		431
210	Call the callback now with the given event mask.	432	Call the callback now with the given event mask.
211		433
		434	=item $w->feed_event ($revents)
		435
		436	Feed some events on this watcher into EV. EV will react to this call as if
		437	the watcher had received the given C<$revents> mask.
		438
		439	=item $revents = $w->clear_pending
		440
		441	If the watcher is pending, this function clears its pending status and
		442	returns its C<$revents> bitset (as if its callback was invoked). If the
		443	watcher isn't pending it does nothing and returns C<0>.
		444
		445	=item $previous_state = $w->keepalive ($bool)
		446
		447	Normally, C<EV::loop> will return when there are no active watchers
		448	(which is a "deadlock" because no progress can be made anymore). This is
		449	convinient because it allows you to start your watchers (and your jobs),
		450	call C<EV::loop> once and when it returns you know that all your jobs are
		451	finished (or they forgot to register some watchers for their task :).
		452
		453	Sometimes, however, this gets in your way, for example when the module
		454	that calls C<EV::loop> (usually the main program) is not the same module
		455	as a long-living watcher (for example a DNS client module written by
		456	somebody else even). Then you might want any outstanding requests to be
		457	handled, but you would not want to keep C<EV::loop> from returning just
		458	because you happen to have this long-running UDP port watcher.
		459
		460	In this case you can clear the keepalive status, which means that even
		461	though your watcher is active, it won't keep C<EV::loop> from returning.
		462
		463	The initial value for keepalive is true (enabled), and you can change it
		464	any time.
		465
		466	Example: Register an I/O watcher for some UDP socket but do not keep the
		467	event loop from running just because of that watcher.
		468
		469	my $udp_socket = ...
		470	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		471	$udp_watcher->keepalive (0);
		472
		473	=item $loop = $w->loop
		474
		475	Return the loop that this watcher is attached to.
		476
		477	=back
		478
		479
		480	=head1 WATCHER TYPES
		481
		482	Each of the following subsections describes a single watcher type.
		483
		484	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		485
		486	=over 4
212		487
213	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	488	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
214		489
215	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	490	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
216		491
		492	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		493
		494	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		495
217	As long as the returned watcher object is alive, call the C<$callback>	496	As long as the returned watcher object is alive, call the C<$callback>
218	when the events specified in C<$eventmask>.	497	when at least one of events specified in C<$eventmask> occurs.
219		498
220	The $eventmask can be one or more of these constants ORed together:	499	The $eventmask can be one or more of these constants ORed together:
221		500
222	EV::READ wait until read() wouldn't block anymore	501	EV::READ wait until read() wouldn't block anymore
223	EV::WRITE wait until write() wouldn't block anymore	502	EV::WRITE wait until write() wouldn't block anymore
…		…
239		518
240	=item $old_eventmask = $w->events ($new_eventmask)	519	=item $old_eventmask = $w->events ($new_eventmask)
241		520
242	Returns the previously set event mask and optionally set a new one.	521	Returns the previously set event mask and optionally set a new one.
243		522
		523	=back
		524
		525
		526	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		527
		528	=over 4
244		529
245	=item $w = EV::timer $after, $repeat, $callback	530	=item $w = EV::timer $after, $repeat, $callback
246		531
247	=item $w = EV::timer_ns $after, $repeat, $callback	532	=item $w = EV::timer_ns $after, $repeat, $callback
248		533
249	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	534	=item $w = $loop->timer ($after, $repeat, $callback)
250	the timer will be restarted (with the $repeat value as $after) after the	535
251	callback returns.	536	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		537
		538	Calls the callback after C<$after> seconds (which may be fractional). If
		539	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		540	value as $after) after the callback returns.
252		541
253	This means that the callback would be called roughly after C<$after>	542	This means that the callback would be called roughly after C<$after>
254	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	543	seconds, and then every C<$repeat> seconds. The timer does his best not
255	callback processing is not taken into account, so the timer will slowly	544	to drift, but it will not invoke the timer more often then once per event
256	drift. If that isn't acceptable, look at EV::periodic.	545	loop iteration, and might drift in other cases. If that isn't acceptable,
		546	look at EV::periodic, which can provide long-term stable timers.
257		547
258	The timer is based on a monotonic clock, that is if somebody is sitting	548	The timer is based on a monotonic clock, that is, if somebody is sitting
259	in front of the machine while the timer is running and changes the system	549	in front of the machine while the timer is running and changes the system
260	clock, the timer will nevertheless run (roughly) the same time.	550	clock, the timer will nevertheless run (roughly) the same time.
261		551
262	The C<timer_ns> variant doesn't start (activate) the newly created watcher.	552	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
263		553
264	=item $w->set ($after, $repeat)	554	=item $w->set ($after, $repeat)
265		555
266	Reconfigures the watcher, see the constructor above for details. Can be at	556	Reconfigures the watcher, see the constructor above for details. Can be called at
267	any time.	557	any time.
268		558
269	=item $w->again	559	=item $w->again
270		560
271	Similar to the C<start> method, but has special semantics for repeating timers:	561	Similar to the C<start> method, but has special semantics for repeating timers:
		562
		563	If the timer is active and non-repeating, it will be stopped.
272		564
273	If the timer is active and repeating, reset the timeout to occur	565	If the timer is active and repeating, reset the timeout to occur
274	C<$repeat> seconds after now.	566	C<$repeat> seconds after now.
275		567
276	If the timer is active and non-repeating, it will be stopped.
277
278	If the timer is in active and repeating, start it.	568	If the timer is inactive and repeating, start it using the repeat value.
279		569
280	Otherwise do nothing.	570	Otherwise do nothing.
281		571
282	This behaviour is useful when you have a timeout for some IO	572	This behaviour is useful when you have a timeout for some IO
283	operation. You create a timer object with the same value for C<$after> and	573	operation. You create a timer object with the same value for C<$after> and
284	C<$repeat>, and then, in the read/write watcher, run the C<again> method	574	C<$repeat>, and then, in the read/write watcher, run the C<again> method
285	on the timeout.	575	on the timeout.
286		576
		577	=back
287		578
		579
		580	=head3 PERIODIC WATCHERS - to cron or not to cron?
		581
		582	=over 4
		583
288	=item $w = EV::periodic $at, $interval, $callback	584	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
289		585
290	=item $w = EV::periodic_ns $at, $interval, $callback	586	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
291		587
292	Similar to EV::timer, but the time is given as an absolute point in time	588	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
293	(C<$at>), plus an optional C<$interval>.
294		589
295	If the C<$interval> is zero, then the callback will be called at the time	590	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
296	C<$at> if that is in the future, or as soon as possible if it is in the
297	past. It will not automatically repeat.
298		591
299	If the C<$interval> is nonzero, then the watcher will always be scheduled	592	Similar to EV::timer, but is not based on relative timeouts but on
300	to time out at the next C<$at + N * $interval> time.	593	absolute times. Apart from creating "simple" timers that trigger "at" the
		594	specified time, it can also be used for non-drifting absolute timers and
		595	more complex, cron-like, setups that are not adversely affected by time
		596	jumps (i.e. when the system clock is changed by explicit date -s or other
		597	means such as ntpd). It is also the most complex watcher type in EV.
301		598
302	This can be used to schedule a callback to run at very regular intervals,	599	It has three distinct "modes":
303	as long as the processing time is less then the interval (otherwise	600
304	obviously events will be skipped).	601	=over 4
		602
		603	=item * absolute timer ($interval = $reschedule_cb = 0)
		604
		605	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		606	will not adjust when a time jump occurs, that is, if it is to be run
		607	at January 1st 2011 then it will run when the system time reaches or
		608	surpasses this time.
		609
		610	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		611
		612	In this mode the watcher will always be scheduled to time out at the
		613	next C<$at + N * $interval> time (for some integer N) and then repeat,
		614	regardless of any time jumps.
		615
		616	This can be used to create timers that do not drift with respect to system
		617	time:
		618
		619	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		620
		621	That doesn't mean there will always be 3600 seconds in between triggers,
		622	but only that the the clalback will be called when the system time shows a
		623	full hour (UTC).
305		624
306	Another way to think about it (for the mathematically inclined) is that	625	Another way to think about it (for the mathematically inclined) is that
307	EV::periodic will try to run the callback at the next possible time where	626	EV::periodic will try to run the callback in this mode at the next
308	C<$time = $at (mod $interval)>, regardless of any time jumps.	627	possible time where C<$time = $at (mod $interval)>, regardless of any time
		628	jumps.
309		629
310	This periodic timer is based on "wallclock time", that is, if the clock	630	=item * manual reschedule mode ($reschedule_cb = coderef)
311	changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at	631
312	the specified time. This means it will never drift (it might jitter, but	632	In this mode $interval and $at are both being ignored. Instead, each
313	it will not drift).	633	time the periodic watcher gets scheduled, the reschedule callback
		634	($reschedule_cb) will be called with the watcher as first, and the current
		635	time as second argument.
		636
		637	I<This callback MUST NOT stop or destroy this or any other periodic
		638	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		639	you need to stop it, return 1e30 and stop it afterwards. You may create
		640	and start a C<EV::prepare> watcher for this task.
		641
		642	It must return the next time to trigger, based on the passed time value
		643	(that is, the lowest time value larger than or equal to to the second
		644	argument). It will usually be called just before the callback will be
		645	triggered, but might be called at other times, too.
		646
		647	This can be used to create very complex timers, such as a timer that
		648	triggers on each midnight, local time (actually 24 hours after the last
		649	midnight, to keep the example simple. If you know a way to do it correctly
		650	in about the same space (without requiring elaborate modules), drop me a
		651	note :):
		652
		653	my $daily = EV::periodic 0, 0, sub {
		654	my ($w, $now) = @_;
		655
		656	use Time::Local ();
		657	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		658	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		659	}, sub {
		660	print "it's midnight or likely shortly after, now\n";
		661	};
		662
		663	=back
314		664
315	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	665	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
316		666
317	=item $w->set ($at, $interval)	667	=item $w->set ($at, $interval, $reschedule_cb)
318		668
319	Reconfigures the watcher, see the constructor above for details. Can be at	669	Reconfigures the watcher, see the constructor above for details. Can be called at
320	any time.	670	any time.
321		671
		672	=item $w->again
		673
		674	Simply stops and starts the watcher again.
		675
		676	=item $time = $w->at
		677
		678	Return the time that the watcher is expected to trigger next.
		679
		680	=back
		681
		682
		683	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		684
		685	=over 4
322		686
323	=item $w = EV::signal $signal, $callback	687	=item $w = EV::signal $signal, $callback
324		688
325	=item $w = EV::signal_ns $signal, $callback	689	=item $w = EV::signal_ns $signal, $callback
326		690
327	Call the callback when $signal is received (the signal can be specified	691	Call the callback when $signal is received (the signal can be specified by
328	by number or by name, just as with kill or %SIG).	692	number or by name, just as with C<kill> or C<%SIG>).
329		693
330	EV will grab the signal for the process (the kernel only allows one	694	EV will grab the signal for the process (the kernel only allows one
331	component to receive a signal at a time) when you start a signal watcher,	695	component to receive a signal at a time) when you start a signal watcher,
332	and removes it again when you stop it. Perl does the same when you	696	and removes it again when you stop it. Perl does the same when you
333	add/remove callbacks to %SIG, so watch out.	697	add/remove callbacks to C<%SIG>, so watch out.
334		698
335	You can have as many signal watchers per signal as you want.	699	You can have as many signal watchers per signal as you want.
336		700
337	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	701	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
338		702
339	=item $w->set ($signal)	703	=item $w->set ($signal)
340		704
341	Reconfigures the watcher, see the constructor above for details. Can be at	705	Reconfigures the watcher, see the constructor above for details. Can be
342	any time.	706	called at any time.
343		707
344	=item $current_signum = $w->signal	708	=item $current_signum = $w->signal
345		709
346	=item $old_signum = $w->signal ($new_signal)	710	=item $old_signum = $w->signal ($new_signal)
347		711
348	Returns the previously set signal (always as a number not name) and	712	Returns the previously set signal (always as a number not name) and
349	optionally set a new one.	713	optionally set a new one.
350		714
		715	=back
351		716
		717
		718	=head3 CHILD WATCHERS - watch out for process status changes
		719
		720	=over 4
		721
352	=item $w = EV::child $pid, $callback	722	=item $w = EV::child $pid, $trace, $callback
353		723
354	=item $w = EV::child_ns $pid, $callback	724	=item $w = EV::child_ns $pid, $trace, $callback
		725
		726	=item $w = $loop->child ($pid, $trace, $callback)
		727
		728	=item $w = $loop->child_ns ($pid, $trace, $callback)
355		729
356	Call the callback when a status change for pid C<$pid> (or any pid	730	Call the callback when a status change for pid C<$pid> (or any pid
357	if C<$pid> is 0) has been received. More precisely: when the process	731	if C<$pid> is 0) has been received (a status change happens when the
		732	process terminates or is killed, or, when trace is true, additionally when
		733	it is stopped or continued). More precisely: when the process receives
358	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	734	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
359	changed/zombie children and call the callback.	735	changed/zombie children and call the callback.
360		736
361	Unlike all other callbacks, this callback will be called with an	737	It is valid (and fully supported) to install a child watcher after a child
362	additional third argument which is the exit status. See the C<waitpid>	738	has exited but before the event loop has started its next iteration (for
363	function for details.	739	example, first you C<fork>, then the new child process might exit, and
		740	only then do you install a child watcher in the parent for the new pid).
364		741
		742	You can access both exit (or tracing) status and pid by using the
		743	C<rstatus> and C<rpid> methods on the watcher object.
		744
365	You can have as many pid watchers per pid as you want.	745	You can have as many pid watchers per pid as you want, they will all be
		746	called.
366		747
367	The C<child_ns> variant doesn't start (activate) the newly created watcher.	748	The C<child_ns> variant doesn't start (activate) the newly created watcher.
368		749
369	=item $w->set ($pid)	750	=item $w->set ($pid, $trace)
370		751
371	Reconfigures the watcher, see the constructor above for details. Can be at	752	Reconfigures the watcher, see the constructor above for details. Can be called at
372	any time.	753	any time.
373		754
374	=item $current_pid = $w->pid	755	=item $current_pid = $w->pid
375		756
376	=item $old_pid = $w->pid ($new_pid)
377
378	Returns the previously set process id and optionally set a new one.	757	Returns the previously set process id and optionally set a new one.
379		758
		759	=item $exit_status = $w->rstatus
		760
		761	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		762	in perlfunc).
		763
		764	=item $pid = $w->rpid
		765
		766	Return the pid of the awaited child (useful when you have installed a
		767	watcher for all pids).
		768
		769	=back
		770
		771
		772	=head3 STAT WATCHERS - did the file attributes just change?
		773
		774	=over 4
		775
		776	=item $w = EV::stat $path, $interval, $callback
		777
		778	=item $w = EV::stat_ns $path, $interval, $callback
		779
		780	=item $w = $loop->stat ($path, $interval, $callback)
		781
		782	=item $w = $loop->stat_ns ($path, $interval, $callback)
		783
		784	Call the callback when a file status change has been detected on
		785	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		786	to "path does not exist" is a status change like any other.
		787
		788	The C<$interval> is a recommended polling interval for systems where
		789	OS-supported change notifications don't exist or are not supported. If
		790	you use C<0> then an unspecified default is used (which is highly
		791	recommended!), which is to be expected to be around five seconds usually.
		792
		793	This watcher type is not meant for massive numbers of stat watchers,
		794	as even with OS-supported change notifications, this can be
		795	resource-intensive.
		796
		797	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		798
		799	=item ... = $w->stat
		800
		801	This call is very similar to the perl C<stat> built-in: It stats (using
		802	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		803	well as EV's idea of the current stat values) to the values found.
		804
		805	In scalar context, a boolean is return indicating success or failure of
		806	the stat. In list context, the same 13-value list as with stat is returned
		807	(except that the blksize and blocks fields are not reliable).
		808
		809	In the case of an error, errno is set to C<ENOENT> (regardless of the
		810	actual error value) and the C<nlink> value is forced to zero (if the stat
		811	was successful then nlink is guaranteed to be non-zero).
		812
		813	See also the next two entries for more info.
		814
		815	=item ... = $w->attr
		816
		817	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		818	the values most recently detected by EV. See the next entry for more info.
		819
		820	=item ... = $w->prev
		821
		822	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		823	the previous set of values, before the change.
		824
		825	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		826	to the values found I<before> a change was detected, while C<< $w->attr >>
		827	returns the values found leading to the change detection. The difference (if any)
		828	between C<prev> and C<attr> is what triggered the callback.
		829
		830	If you did something to the filesystem object and do not want to trigger
		831	yet another change, you can call C<stat> to update EV's idea of what the
		832	current attributes are.
		833
		834	=item $w->set ($path, $interval)
		835
		836	Reconfigures the watcher, see the constructor above for details. Can be
		837	called at any time.
		838
		839	=item $current_path = $w->path
		840
		841	=item $old_path = $w->path ($new_path)
		842
		843	Returns the previously set path and optionally set a new one.
		844
		845	=item $current_interval = $w->interval
		846
		847	=item $old_interval = $w->interval ($new_interval)
		848
		849	Returns the previously set interval and optionally set a new one. Can be
		850	used to query the actual interval used.
		851
		852	=back
		853
		854
		855	=head3 IDLE WATCHERS - when you've got nothing better to do...
		856
		857	=over 4
380		858
381	=item $w = EV::idle $callback	859	=item $w = EV::idle $callback
382		860
383	=item $w = EV::idle_ns $callback	861	=item $w = EV::idle_ns $callback
384		862
385	Call the callback when there are no pending io, timer/periodic, signal or	863	=item $w = $loop->idle ($callback)
386	child events, i.e. when the process is idle.	864
		865	=item $w = $loop->idle_ns ($callback)
		866
		867	Call the callback when there are no other pending watchers of the same or
		868	higher priority (excluding check, prepare and other idle watchers of the
		869	same or lower priority, of course). They are called idle watchers because
		870	when the watcher is the highest priority pending event in the process, the
		871	process is considered to be idle at that priority.
		872
		873	If you want a watcher that is only ever called when I<no> other events are
		874	outstanding you have to set the priority to C<EV::MINPRI>.
387		875
388	The process will not block as long as any idle watchers are active, and	876	The process will not block as long as any idle watchers are active, and
389	they will be called repeatedly until stopped.	877	they will be called repeatedly until stopped.
390		878
		879	For example, if you have idle watchers at priority C<0> and C<1>, and
		880	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		881	and the I/O watcher will always run when ready. Only when the idle watcher
		882	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		883	pending with the C<0>-priority idle watcher be invoked.
		884
391	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	885	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
392		886
		887	=back
		888
		889
		890	=head3 PREPARE WATCHERS - customise your event loop!
		891
		892	=over 4
393		893
394	=item $w = EV::prepare $callback	894	=item $w = EV::prepare $callback
395		895
396	=item $w = EV::prepare_ns $callback	896	=item $w = EV::prepare_ns $callback
		897
		898	=item $w = $loop->prepare ($callback)
		899
		900	=item $w = $loop->prepare_ns ($callback)
397		901
398	Call the callback just before the process would block. You can still	902	Call the callback just before the process would block. You can still
399	create/modify any watchers at this point.	903	create/modify any watchers at this point.
400		904
401	See the EV::check watcher, below, for explanations and an example.	905	See the EV::check watcher, below, for explanations and an example.
402		906
403	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	907	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
404		908
		909	=back
		910
		911
		912	=head3 CHECK WATCHERS - customise your event loop even more!
		913
		914	=over 4
405		915
406	=item $w = EV::check $callback	916	=item $w = EV::check $callback
407		917
408	=item $w = EV::check_ns $callback	918	=item $w = EV::check_ns $callback
		919
		920	=item $w = $loop->check ($callback)
		921
		922	=item $w = $loop->check_ns ($callback)
409		923
410	Call the callback just after the process wakes up again (after it has	924	Call the callback just after the process wakes up again (after it has
411	gathered events), but before any other callbacks have been invoked.	925	gathered events), but before any other callbacks have been invoked.
412		926
413	This is used to integrate other event-based software into the EV	927	This is used to integrate other event-based software into the EV
…		…
421	# do nothing unless active	935	# do nothing unless active
422	$dispatcher->{_event_queue_h}	936	$dispatcher->{_event_queue_h}
423	or return;	937	or return;
424		938
425	# make the dispatcher handle any outstanding stuff	939	# make the dispatcher handle any outstanding stuff
		940	... not shown
426		941
427	# create an IO watcher for each and every socket	942	# create an I/O watcher for each and every socket
428	@snmp_watcher = (	943	@snmp_watcher = (
429	(map { EV::io $_, EV::READ, sub { } }	944	(map { EV::io $_, EV::READ, sub { } }
430	keys %{ $dispatcher->{_descriptors} }),	945	keys %{ $dispatcher->{_descriptors} }),
		946
		947	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		948	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		949	0, sub { },
431	);	950	);
432
433	# if there are any timeouts, also create a timer
434	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
435	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
436	};	951	};
437		952
438	The callbacks are irrelevant, the only purpose of those watchers is	953	The callbacks are irrelevant (and are not even being called), the
439	to wake up the process as soon as one of those events occurs (socket	954	only purpose of those watchers is to wake up the process as soon as
440	readable, or timer timed out). The corresponding EV::check watcher will then	955	one of those events occurs (socket readable, or timer timed out). The
441	clean up:	956	corresponding EV::check watcher will then clean up:
442		957
443	our $snmp_check = EV::check sub {	958	our $snmp_check = EV::check sub {
444	# destroy all watchers	959	# destroy all watchers
445	@snmp_watcher = ();	960	@snmp_watcher = ();
446		961
447	# make the dispatcher handle any new stuff	962	# make the dispatcher handle any new stuff
		963	... not shown
448	};	964	};
449		965
450	The callbacks of the created watchers will not be called as the watchers	966	The callbacks of the created watchers will not be called as the watchers
451	are destroyed before this cna happen (remember EV::check gets called	967	are destroyed before this can happen (remember EV::check gets called
452	first).	968	first).
453		969
454	The C<check_ns> variant doesn't start (activate) the newly created watcher.	970	The C<check_ns> variant doesn't start (activate) the newly created watcher.
455		971
456	=back	972	=back
457		973
		974
		975	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		976
		977	Fork watchers are called when a C<fork ()> was detected. The invocation
		978	is done before the event loop blocks next and before C<check> watchers
		979	are being called, and only in the child after the fork.
		980
		981	=over 4
		982
		983	=item $w = EV::fork $callback
		984
		985	=item $w = EV::fork_ns $callback
		986
		987	=item $w = $loop->fork ($callback)
		988
		989	=item $w = $loop->fork_ns ($callback)
		990
		991	Call the callback before the event loop is resumed in the child process
		992	after a fork.
		993
		994	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		995
		996	=back
		997
		998
		999	=head3 EMBED WATCHERS - when one backend isn't enough...
		1000
		1001	This is a rather advanced watcher type that lets you embed one event loop
		1002	into another (currently only IO events are supported in the embedded
		1003	loop, other types of watchers might be handled in a delayed or incorrect
		1004	fashion and must not be used).
		1005
		1006	See the libev documentation at
		1007	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1008	(locally installed as F<EV::libev>) for more details.
		1009
		1010	In short, this watcher is most useful on BSD systems without working
		1011	kqueue to still be able to handle a large number of sockets:
		1012
		1013	my $socket_loop;
		1014
		1015	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1016	if (
		1017	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1018	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1019	) {
		1020	# use kqueue for sockets
		1021	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1022	}
		1023
		1024	# use the default loop otherwise
		1025	$socket_loop \|\|= EV::default_loop;
		1026
		1027	=over 4
		1028
		1029	=item $w = EV::embed $otherloop[, $callback]
		1030
		1031	=item $w = EV::embed_ns $otherloop[, $callback]
		1032
		1033	=item $w = $loop->embed ($otherloop[, $callback])
		1034
		1035	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1036
		1037	Call the callback when the embedded event loop (C<$otherloop>) has any
		1038	I/O activity. The C<$callback> is optional: if it is missing, then the
		1039	embedded event loop will be managed automatically (which is recommended),
		1040	otherwise you have to invoke C<sweep> yourself.
		1041
		1042	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1043
		1044	=back
		1045
		1046	=head3 ASYNC WATCHERS - how to wake up another event loop
		1047
		1048	Async watchers are provided by EV, but have little use in perl directly,
		1049	as perl neither supports threads running in parallel nor direct access to
		1050	signal handlers or other contexts where they could be of value.
		1051
		1052	It is, however, possible to use them from the XS level.
		1053
		1054	Please see the libev documentation for further details.
		1055
		1056	=over 4
		1057
		1058	=item $w = EV::async $callback
		1059
		1060	=item $w = EV::async_ns $callback
		1061
		1062	=item $w->send
		1063
		1064	=item $bool = $w->async_pending
		1065
		1066	=back
		1067
		1068
		1069	=head1 PERL SIGNALS
		1070
		1071	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1072	with EV is as the same as any other C library: Perl-signals will only be
		1073	handled when Perl runs, which means your signal handler might be invoked
		1074	only the next time an event callback is invoked.
		1075
		1076	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1077	ensure proper operations with regards to other event watchers.
		1078
		1079	If you cannot do this for whatever reason, you can also force a watcher
		1080	to be called on every event loop iteration by installing a C<EV::check>
		1081	watcher:
		1082
		1083	my $async_check = EV::check sub { };
		1084
		1085	This ensures that perl gets into control for a short time to handle any
		1086	pending signals, and also ensures (slightly) slower overall operation.
		1087
458	=head1 THREADS	1088	=head1 ITHREADS
459		1089
460	Threads are not supported by this in any way. Perl pseudo-threads is evil	1090	Ithreads are not supported by this module in any way. Perl pseudo-threads
461	stuff and must die.	1091	is evil stuff and must die. Real threads as provided by Coro are fully
		1092	supported (and enhanced support is available via L<Coro::EV>).
		1093
		1094	=head1 FORK
		1095
		1096	Most of the "improved" event delivering mechanisms of modern operating
		1097	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1098	not supported and usually destructive). Libev makes it possible to work
		1099	around this by having a function that recreates the kernel state after
		1100	fork in the child.
		1101
		1102	On non-win32 platforms, this module requires the pthread_atfork
		1103	functionality to do this automatically for you. This function is quite
		1104	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1105	negligible, because everything the function currently does is set a flag
		1106	that is checked only when the event loop gets used the next time, so when
		1107	you do fork but not use EV, the overhead is minimal.
		1108
		1109	On win32, there is no notion of fork so all this doesn't apply, of course.
462		1110
463	=cut	1111	=cut
464		1112
465	our $DIED = sub {	1113	our $DIED = sub {
466	warn "EV: error in callback (ignoring): $@";	1114	warn "EV: error in callback (ignoring): $@";
467	};	1115	};
468		1116
469	init;	1117	default_loop
470		1118	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
471	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
472		1119
473	1;	1120	1;
474		1121
475	=head1 SEE ALSO	1122	=head1 SEE ALSO
476		1123
477	L<EV::DNS>, L<EV::AnyEvent>.	1124	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
		1125	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1126	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1127	event-loop agnostic and portable event driven programming.
478		1128
479	=head1 AUTHOR	1129	=head1 AUTHOR
480		1130
481	Marc Lehmann <schmorp@schmorp.de>	1131	Marc Lehmann <schmorp@schmorp.de>
482	http://home.schmorp.de/	1132	http://home.schmorp.de/
483		1133
484	=cut	1134	=cut
485		1135

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Comparing EV/EV.pm (file contents): Revision 1.24 by root, Fri Nov 2 22:03:00 2007 UTC vs. Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.24 by root, Fri Nov 2 22:03:00 2007 UTC vs.
Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC