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

Comparing EV/EV.pm (file contents):
Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs.
Revision 1.135 by root, Mon Dec 12 16:32:24 2011 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 {
13	};
14
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, 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 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, $revents) = @_;	47	my ($w, $revents) = @_;
46	# my $pid = $w->rpid;	48	warn $w->path, " has changed somehow.\n";
47	my $status = $w->rstatus;
48	};	49	};
49		50
50	# MAINLOOP	51	# MAINLOOP
51	EV::loop; # loop until EV::loop_done is called	52	EV::run; # loop until EV::unloop is called or all watchers stop
52	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled	53	EV::run EV::RUN_ONCE; # block until at least one event could be handled
53	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block	54	EV::run EV::RUN_NOWAIT; # try to handle same events, but do not block
		55
		56	=head1 BEFORE YOU START USING THIS MODULE
		57
		58	If you only need timer, I/O, signal, child and idle watchers and not the
		59	advanced functionality of this module, consider using L<AnyEvent> instead,
		60	specifically the simplified API described in L<AE>.
		61
		62	When used with EV as backend, the L<AE> API is as fast as the native L<EV>
		63	API, but your programs/modules will still run with many other event loops.
54		64
55	=head1 DESCRIPTION	65	=head1 DESCRIPTION
56		66
57	This module provides an interface to libev	67	This module provides an interface to libev
58	(L<http://software.schmorp.de/pkg/libev.html>).	68	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		69	below is comprehensive, one might also consult the documentation of
		70	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		71	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		72	discussion on the available backends, or how to force a specific backend
		73	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		74	detailed information.
		75
		76	This module is very fast and scalable. It is actually so fast that you
		77	can use it through the L<AnyEvent> module, stay portable to other event
		78	loops (if you don't rely on any watcher types not available through it)
		79	and still be faster than with any other event loop currently supported in
		80	Perl.
		81
		82	=head2 PORTING FROM EV 3.X to 4.X
		83
		84	EV version 4 introduces a number of incompatible changes summarised
		85	here. According to the depreciation strategy used by libev, there is a
		86	compatibility layer in place so programs should continue to run unchanged
		87	(the XS interface lacks this layer, so programs using that one need to be
		88	updated).
		89
		90	This compatibility layer will be switched off in some future release.
		91
		92	All changes relevant to Perl are renames of symbols, functions and
		93	methods:
		94
		95	EV::loop => EV::run
		96	EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
		97	EV::LOOP_ONESHOT => EV::RUN_ONCE
		98
		99	EV::unloop => EV::break
		100	EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
		101	EV::UNLOOP_ONE => EV::BREAK_ONE
		102	EV::UNLOOP_ALL => EV::BREAK_ALL
		103
		104	EV::TIMEOUT => EV::TIMER
		105
		106	EV::loop_count => EV::iteration
		107	EV::loop_depth => EV::depth
		108	EV::loop_verify => EV::verify
		109
		110	The loop object methods corresponding to the functions above have been
		111	similarly renamed.
		112
		113	=head2 MODULE EXPORTS
		114
		115	This module does not export any symbols.
59		116
60	=cut	117	=cut
61		118
62	package EV;	119	package EV;
63		120
64	use strict;	121	use common::sense;
65		122
66	BEGIN {	123	BEGIN {
67	our $VERSION = '0.7';	124	our $VERSION = '4.03';
68	use XSLoader;	125	use XSLoader;
69	XSLoader::load "EV", $VERSION;	126	XSLoader::load "EV", $VERSION;
70	}	127	}
71		128
72	@EV::Io::ISA =	129	@EV::IO::ISA =
73	@EV::Timer::ISA =	130	@EV::Timer::ISA =
74	@EV::Periodic::ISA =	131	@EV::Periodic::ISA =
75	@EV::Signal::ISA =	132	@EV::Signal::ISA =
		133	@EV::Child::ISA =
		134	@EV::Stat::ISA =
76	@EV::Idle::ISA =	135	@EV::Idle::ISA =
77	@EV::Prepare::ISA =	136	@EV::Prepare::ISA =
78	@EV::Check::ISA =	137	@EV::Check::ISA =
79	@EV::Child::ISA = "EV::Watcher";	138	@EV::Embed::ISA =
		139	@EV::Fork::ISA =
		140	@EV::Async::ISA =
		141	"EV::Watcher";
		142
		143	@EV::Loop::Default::ISA = "EV::Loop";
		144
		145	=head1 EVENT LOOPS
		146
		147	EV supports multiple event loops: There is a single "default event loop"
		148	that can handle everything including signals and child watchers, and any
		149	number of "dynamic event loops" that can use different backends (with
		150	various limitations), but no child and signal watchers.
		151
		152	You do not have to do anything to create the default event loop: When
		153	the module is loaded a suitable backend is selected on the premise of
		154	selecting a working backend (which for example rules out kqueue on most
		155	BSDs). Modules should, unless they have "special needs" always use the
		156	default loop as this is fastest (perl-wise), best supported by other
		157	modules (e.g. AnyEvent or Coro) and most portable event loop.
		158
		159	For specific programs you can create additional event loops dynamically.
		160
		161	If you want to take advantage of kqueue (which often works properly for
		162	sockets only) even though the default loop doesn't enable it, you can
		163	I<embed> a kqueue loop into the default loop: running the default loop
		164	will then also service the kqueue loop to some extent. See the example in
		165	the section about embed watchers for an example on how to achieve that.
		166
		167	=over 4
		168
		169	=item $loop = new EV::Loop [$flags]
		170
		171	Create a new event loop as per the specified flags. Please refer to
		172	the C<ev_loop_new ()> function description in the libev documentation
		173	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		174	or locally-installed as F<EV::libev> manpage) for more info.
		175
		176	The loop will automatically be destroyed when it is no longer referenced
		177	by any watcher and the loop object goes out of scope.
		178
		179	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		180	is recommended, as only the default event loop is protected by this
		181	module. If you I<are> embedding this loop in the default loop, this is not
		182	necessary, as C<EV::embed> automatically does the right thing on fork.
		183
		184	=item $loop->loop_fork
		185
		186	Must be called after a fork in the child, before entering or continuing
		187	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		188	this function automatically, at some performance loss (refer to the libev
		189	documentation).
		190
		191	=item $loop->verify
		192
		193	Calls C<ev_verify> to make internal consistency checks (for debugging
		194	libev) and abort the program if any data structures were found to be
		195	corrupted.
		196
		197	=item $loop = EV::default_loop [$flags]
		198
		199	Return the default loop (which is a singleton object). Since this module
		200	already creates the default loop with default flags, specifying flags here
		201	will not have any effect unless you destroy the default loop first, which
		202	isn't supported. So in short: don't do it, and if you break it, you get to
		203	keep the pieces.
		204
		205	=back
		206
80		207
81	=head1 BASIC INTERFACE	208	=head1 BASIC INTERFACE
82		209
83	=over 4	210	=over 4
84		211
85	=item $EV::DIED	212	=item $EV::DIED
86		213
87	Must contain a reference to a function that is called when a callback	214	Must contain a reference to a function that is called when a callback
88	throws an exception (with $@ containing thr error). The default prints an	215	throws an exception (with $@ containing the error). The default prints an
89	informative message and continues.	216	informative message and continues.
90		217
91	If this callback throws an exception it will be silently ignored.	218	If this callback throws an exception it will be silently ignored.
92		219
		220	=item $flags = EV::supported_backends
		221
		222	=item $flags = EV::recommended_backends
		223
		224	=item $flags = EV::embeddable_backends
		225
		226	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		227	instance of EV, the set of recommended backends (supposed to be good) for
		228	this platform and the set of embeddable backends (see EMBED WATCHERS).
		229
		230	=item EV::sleep $seconds
		231
		232	Block the process for the given number of (fractional) seconds.
		233
93	=item $time = EV::time	234	=item $time = EV::time
94		235
95	Returns the current time in (fractional) seconds since the epoch.	236	Returns the current time in (fractional) seconds since the epoch.
96		237
97	=item $time = EV::now	238	=item $time = EV::now
98		239
		240	=item $time = $loop->now
		241
99	Returns the time the last event loop iteration has been started. This	242	Returns the time the last event loop iteration has been started. This
100	is the time that (relative) timers are based on, and refering to it is	243	is the time that (relative) timers are based on, and referring to it is
101	usually faster then calling EV::time.	244	usually faster then calling EV::time.
102		245
103	=item $method = EV::ev_method	246	=item EV::now_update
104		247
		248	=item $loop->now_update
		249
		250	Establishes the current time by querying the kernel, updating the time
		251	returned by C<EV::now> in the progress. This is a costly operation and
		252	is usually done automatically within C<EV::loop>.
		253
		254	This function is rarely useful, but when some event callback runs for a
		255	very long time without entering the event loop, updating libev's idea of
		256	the current time is a good idea.
		257
		258	=item EV::suspend
		259
		260	=item $loop->suspend
		261
		262	=item EV::resume
		263
		264	=item $loop->resume
		265
		266	These two functions suspend and resume a loop, for use when the loop is
		267	not used for a while and timeouts should not be processed.
		268
		269	A typical use case would be an interactive program such as a game: When
		270	the user presses C<^Z> to suspend the game and resumes it an hour later it
		271	would be best to handle timeouts as if no time had actually passed while
		272	the program was suspended. This can be achieved by calling C<suspend>
		273	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		274	C<resume> directly afterwards to resume timer processing.
		275
		276	Effectively, all C<timer> watchers will be delayed by the time spend
		277	between C<suspend> and C<resume>, and all C<periodic> watchers
		278	will be rescheduled (that is, they will lose any events that would have
		279	occured while suspended).
		280
		281	After calling C<suspend> you B<must not> call I<any> function on the given
		282	loop other than C<resume>, and you B<must not> call C<resume>
		283	without a previous call to C<suspend>.
		284
		285	Calling C<suspend>/C<resume> has the side effect of updating the event
		286	loop time (see C<now_update>).
		287
		288	=item $backend = EV::backend
		289
		290	=item $backend = $loop->backend
		291
105	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	292	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
106	or EV::METHOD_EPOLL).	293	or EV::BACKEND_EPOLL).
107		294
108	=item EV::loop [$flags]	295	=item EV::run [$flags]
		296
		297	=item $loop->run ([$flags])
109		298
110	Begin checking for events and calling callbacks. It returns when a	299	Begin checking for events and calling callbacks. It returns when a
111	callback calls EV::loop_done.	300	callback calls EV::unloop.
112		301
113	The $flags argument can be one of the following:	302	The $flags argument can be one of the following:
114		303
115	0 as above	304	0 as above
116	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	305	EV::RUN_ONCE block at most once (wait, but do not loop)
117	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	306	EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
118		307
119	=item EV::loop_done [$how]	308	=item EV::break [$how]
120		309
		310	=item $loop->break ([$how])
		311
121	When called with no arguments or an argument of 1, makes the innermost	312	When called with no arguments or an argument of EV::BREAK_ONE, makes the
122	call to EV::loop return.	313	innermost call to EV::loop return.
123		314
124	When called with an agrument of 2, all calls to EV::loop will return as	315	When called with an argument of EV::BREAK_ALL, all calls to EV::loop will
125	fast as possible.	316	return as fast as possible.
126		317
127	=back	318	When called with an argument of EV::BREAK_CANCEL, any pending break will
		319	be cancelled.
128		320
129	=head2 WATCHER	321	=item $count = EV::iteration
		322
		323	=item $count = $loop->iteration
		324
		325	Return the number of times the event loop has polled for new
		326	events. Sometimes useful as a generation counter.
		327
		328	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		329
		330	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		331
		332	This function rolls together an I/O and a timer watcher for a single
		333	one-shot event without the need for managing a watcher object.
		334
		335	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		336	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		337	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		338	you do not want to wait for some I/O event, specify C<undef> for
		339	C<$fh_or_undef> and C<0> for C<$events>).
		340
		341	If timeout is C<undef> or negative, then there will be no
		342	timeout. Otherwise a EV::timer with this value will be started.
		343
		344	When an error occurs or either the timeout or I/O watcher triggers, then
		345	the callback will be called with the received event set (in general
		346	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		347	C<EV::WRITE> and C<EV::TIMER>).
		348
		349	EV::once doesn't return anything: the watchers stay active till either
		350	of them triggers, then they will be stopped and freed, and the callback
		351	invoked.
		352
		353	=item EV::feed_fd_event $fd, $revents
		354
		355	=item $loop->feed_fd_event ($fd, $revents)
		356
		357	Feed an event on a file descriptor into EV. EV will react to this call as
		358	if the readyness notifications specified by C<$revents> (a combination of
		359	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		360
		361	=item EV::feed_signal_event $signal
		362
		363	Feed a signal event into the default loop. EV will react to this call as
		364	if the signal specified by C<$signal> had occured.
		365
		366	=item EV::feed_signal $signal
		367
		368	Feed a signal event into EV - unlike C<EV::feed_signal_event>, this works
		369	regardless of which loop has registered the signal, and is mainly useful
		370	fro custom signal implementations.
		371
		372	=item EV::set_io_collect_interval $time
		373
		374	=item $loop->set_io_collect_interval ($time)
		375
		376	=item EV::set_timeout_collect_interval $time
		377
		378	=item $loop->set_timeout_collect_interval ($time)
		379
		380	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		381	wait interval for timer events. See the libev documentation at
		382	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		383	(locally installed as F<EV::libev>) for a more detailed discussion.
		384
		385	=item $count = EV::pending_count
		386
		387	=item $count = $loop->pending_count
		388
		389	Returns the number of currently pending watchers.
		390
		391	=item EV::invoke_pending
		392
		393	=item $loop->invoke_pending
		394
		395	Invoke all currently pending watchers.
		396
		397	=back
		398
		399
		400	=head1 WATCHER OBJECTS
130		401
131	A watcher is an object that gets created to record your interest in some	402	A watcher is an object that gets created to record your interest in some
132	event. For instance, if you want to wait for STDIN to become readable, you	403	event. For instance, if you want to wait for STDIN to become readable, you
133	would create an EV::io watcher for that:	404	would create an EV::io watcher for that:
134		405
135	my $watcher = EV::io *STDIN, EV::READ, sub {	406	my $watcher = EV::io *STDIN, EV::READ, sub {
136	my ($watcher, $revents) = @_;	407	my ($watcher, $revents) = @_;
137	warn "yeah, STDIN should not be readable without blocking!\n"	408	warn "yeah, STDIN should now be readable without blocking!\n"
138	};	409	};
139		410
140	All watchers can be active (waiting for events) or inactive (paused). Only	411	All watchers can be active (waiting for events) or inactive (paused). Only
141	active watchers will have their callbacks invoked. All callbacks will be	412	active watchers will have their callbacks invoked. All callbacks will be
142	called with at least two arguments: the watcher and a bitmask of received	413	called with at least two arguments: the watcher and a bitmask of received
143	events.	414	events.
144		415
145	Each watcher type has its associated bit in revents, so you can use the	416	Each watcher type has its associated bit in revents, so you can use the
146	same callback for multiple watchers. The event mask is named after the	417	same callback for multiple watchers. The event mask is named after the
147	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,	418	type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events	419	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which	420	(which can set both EV::READ and EV::WRITE bits).
150	uses EV::TIMEOUT).
151		421
152	In the rare case where one wants to create a watcher but not start it at	422	In the rare case where one wants to create a watcher but not start it at
153	the same time, each constructor has a variant with a trailing C<_ns> in	423	the same time, each constructor has a variant with a trailing C<_ns> in
154	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.	424	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
155		425
…		…
159		429
160	Also, all methods changing some aspect of a watcher (->set, ->priority,	430	Also, all methods changing some aspect of a watcher (->set, ->priority,
161	->fh and so on) automatically stop and start it again if it is active,	431	->fh and so on) automatically stop and start it again if it is active,
162	which means pending events get lost.	432	which means pending events get lost.
163		433
164	=head2 WATCHER TYPES	434	=head2 COMMON WATCHER METHODS
165		435
166	Now lets move to the existing watcher types and asociated methods.	436	This section lists methods common to all watchers.
167
168	The following methods are available for all watchers. Then followes a
169	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
170	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
171	any type-specific methods (if any).
172		437
173	=over 4	438	=over 4
174		439
175	=item $w->start	440	=item $w->start
176		441
…		…
180		445
181	=item $w->stop	446	=item $w->stop
182		447
183	Stop a watcher if it is active. Also clear any pending events (events that	448	Stop a watcher if it is active. Also clear any pending events (events that
184	have been received but that didn't yet result in a callback invocation),	449	have been received but that didn't yet result in a callback invocation),
185	regardless of wether the watcher was active or not.	450	regardless of whether the watcher was active or not.
186		451
187	=item $bool = $w->is_active	452	=item $bool = $w->is_active
188		453
189	Returns true if the watcher is active, false otherwise.	454	Returns true if the watcher is active, false otherwise.
190		455
…		…
215	watchers with higher priority will be invoked first. The valid range of	480	watchers with higher priority will be invoked first. The valid range of
216	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default	481	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
217	-2). If the priority is outside this range it will automatically be	482	-2). If the priority is outside this range it will automatically be
218	normalised to the nearest valid priority.	483	normalised to the nearest valid priority.
219		484
220	The default priority of any newly-created weatcher is 0.	485	The default priority of any newly-created watcher is 0.
221		486
		487	Note that the priority semantics have not yet been fleshed out and are
		488	subject to almost certain change.
		489
222	=item $w->trigger ($revents)	490	=item $w->invoke ($revents)
223		491
224	Call the callback now with the given event mask.	492	Call the callback now with the given event mask.
225		493
		494	=item $w->feed_event ($revents)
		495
		496	Feed some events on this watcher into EV. EV will react to this call as if
		497	the watcher had received the given C<$revents> mask.
		498
		499	=item $revents = $w->clear_pending
		500
		501	If the watcher is pending, this function clears its pending status and
		502	returns its C<$revents> bitset (as if its callback was invoked). If the
		503	watcher isn't pending it does nothing and returns C<0>.
		504
		505	=item $previous_state = $w->keepalive ($bool)
		506
		507	Normally, C<EV::loop> will return when there are no active watchers
		508	(which is a "deadlock" because no progress can be made anymore). This is
		509	convenient because it allows you to start your watchers (and your jobs),
		510	call C<EV::loop> once and when it returns you know that all your jobs are
		511	finished (or they forgot to register some watchers for their task :).
		512
		513	Sometimes, however, this gets in your way, for example when the module
		514	that calls C<EV::loop> (usually the main program) is not the same module
		515	as a long-living watcher (for example a DNS client module written by
		516	somebody else even). Then you might want any outstanding requests to be
		517	handled, but you would not want to keep C<EV::loop> from returning just
		518	because you happen to have this long-running UDP port watcher.
		519
		520	In this case you can clear the keepalive status, which means that even
		521	though your watcher is active, it won't keep C<EV::loop> from returning.
		522
		523	The initial value for keepalive is true (enabled), and you can change it
		524	any time.
		525
		526	Example: Register an I/O watcher for some UDP socket but do not keep the
		527	event loop from running just because of that watcher.
		528
		529	my $udp_socket = ...
		530	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		531	$udp_watcher->keepalive (0);
		532
		533	=item $loop = $w->loop
		534
		535	Return the loop that this watcher is attached to.
		536
		537	=back
		538
		539
		540	=head1 WATCHER TYPES
		541
		542	Each of the following subsections describes a single watcher type.
		543
		544	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		545
		546	=over 4
226		547
227	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	548	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
228		549
229	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	550	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
230		551
		552	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		553
		554	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		555
231	As long as the returned watcher object is alive, call the C<$callback>	556	As long as the returned watcher object is alive, call the C<$callback>
232	when the events specified in C<$eventmask>.	557	when at least one of events specified in C<$eventmask> occurs.
233		558
234	The $eventmask can be one or more of these constants ORed together:	559	The $eventmask can be one or more of these constants ORed together:
235		560
236	EV::READ wait until read() wouldn't block anymore	561	EV::READ wait until read() wouldn't block anymore
237	EV::WRITE wait until write() wouldn't block anymore	562	EV::WRITE wait until write() wouldn't block anymore
…		…
253		578
254	=item $old_eventmask = $w->events ($new_eventmask)	579	=item $old_eventmask = $w->events ($new_eventmask)
255		580
256	Returns the previously set event mask and optionally set a new one.	581	Returns the previously set event mask and optionally set a new one.
257		582
		583	=back
		584
		585
		586	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		587
		588	=over 4
258		589
259	=item $w = EV::timer $after, $repeat, $callback	590	=item $w = EV::timer $after, $repeat, $callback
260		591
261	=item $w = EV::timer_ns $after, $repeat, $callback	592	=item $w = EV::timer_ns $after, $repeat, $callback
262		593
263	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	594	=item $w = $loop->timer ($after, $repeat, $callback)
264	the timer will be restarted (with the $repeat value as $after) after the	595
265	callback returns.	596	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		597
		598	Calls the callback after C<$after> seconds (which may be fractional). If
		599	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		600	value as $after) after the callback returns.
266		601
267	This means that the callback would be called roughly after C<$after>	602	This means that the callback would be called roughly after C<$after>
268	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	603	seconds, and then every C<$repeat> seconds. The timer does his best not
269	callback processing is not taken into account, so the timer will slowly	604	to drift, but it will not invoke the timer more often then once per event
270	drift. If that isn't acceptable, look at EV::periodic.	605	loop iteration, and might drift in other cases. If that isn't acceptable,
		606	look at EV::periodic, which can provide long-term stable timers.
271		607
272	The timer is based on a monotonic clock, that is if somebody is sitting	608	The timer is based on a monotonic clock, that is, if somebody is sitting
273	in front of the machine while the timer is running and changes the system	609	in front of the machine while the timer is running and changes the system
274	clock, the timer will nevertheless run (roughly) the same time.	610	clock, the timer will nevertheless run (roughly) the same time.
275		611
276	The C<timer_ns> variant doesn't start (activate) the newly created watcher.	612	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
277		613
278	=item $w->set ($after, $repeat)	614	=item $w->set ($after, $repeat)
279		615
280	Reconfigures the watcher, see the constructor above for details. Can be at	616	Reconfigures the watcher, see the constructor above for details. Can be called at
281	any time.	617	any time.
282		618
283	=item $w->again	619	=item $w->again
284		620
285	Similar to the C<start> method, but has special semantics for repeating timers:	621	Similar to the C<start> method, but has special semantics for repeating timers:
		622
		623	If the timer is active and non-repeating, it will be stopped.
286		624
287	If the timer is active and repeating, reset the timeout to occur	625	If the timer is active and repeating, reset the timeout to occur
288	C<$repeat> seconds after now.	626	C<$repeat> seconds after now.
289		627
290	If the timer is active and non-repeating, it will be stopped.
291
292	If the timer is in active and repeating, start it.	628	If the timer is inactive and repeating, start it using the repeat value.
293		629
294	Otherwise do nothing.	630	Otherwise do nothing.
295		631
296	This behaviour is useful when you have a timeout for some IO	632	This behaviour is useful when you have a timeout for some IO
297	operation. You create a timer object with the same value for C<$after> and	633	operation. You create a timer object with the same value for C<$after> and
298	C<$repeat>, and then, in the read/write watcher, run the C<again> method	634	C<$repeat>, and then, in the read/write watcher, run the C<again> method
299	on the timeout.	635	on the timeout.
300		636
		637	=back
		638
		639
		640	=head3 PERIODIC WATCHERS - to cron or not to cron?
		641
		642	=over 4
301		643
302	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback	644	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
303		645
304	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback	646	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		647
		648	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		649
		650	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305		651
306	Similar to EV::timer, but is not based on relative timeouts but on	652	Similar to EV::timer, but is not based on relative timeouts but on
307	absolute times. Apart from creating "simple" timers that trigger "at" the	653	absolute times. Apart from creating "simple" timers that trigger "at" the
308	specified time, it can also be used for non-drifting absolute timers and	654	specified time, it can also be used for non-drifting absolute timers and
309	more complex, cron-like, setups that are not adversely affected by time	655	more complex, cron-like, setups that are not adversely affected by time
…		…
319	This time simply fires at the wallclock time C<$at> and doesn't repeat. It	665	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
320	will not adjust when a time jump occurs, that is, if it is to be run	666	will not adjust when a time jump occurs, that is, if it is to be run
321	at January 1st 2011 then it will run when the system time reaches or	667	at January 1st 2011 then it will run when the system time reaches or
322	surpasses this time.	668	surpasses this time.
323		669
324	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)	670	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
325		671
326	In this mode the watcher will always be scheduled to time out at the	672	In this mode the watcher will always be scheduled to time out at the
327	next C<$at + N * $interval> time (for some integer N) and then repeat,	673	next C<$at + N * $interval> time (for some integer N) and then repeat,
328	regardless of any time jumps.	674	regardless of any time jumps.
329		675
…		…
341	possible time where C<$time = $at (mod $interval)>, regardless of any time	687	possible time where C<$time = $at (mod $interval)>, regardless of any time
342	jumps.	688	jumps.
343		689
344	=item * manual reschedule mode ($reschedule_cb = coderef)	690	=item * manual reschedule mode ($reschedule_cb = coderef)
345		691
346	In this mode $interval and $at are both being ignored. Instead, each time	692	In this mode $interval and $at are both being ignored. Instead, each
347	the periodic watcher gets scheduled, the first callback ($reschedule_cb)	693	time the periodic watcher gets scheduled, the reschedule callback
348	will be called with the watcher as first, and the current time as second	694	($reschedule_cb) will be called with the watcher as first, and the current
349	argument.	695	time as second argument.
350		696
351	I<This callback MUST NOT stop or destroy this or any other periodic	697	I<This callback MUST NOT stop or destroy this or any other periodic
352	watcher, ever>. If you need to stop it, return 1e30 and stop it	698	watcher, ever, and MUST NOT call any event loop functions or methods>. If
353	afterwards.	699	you need to stop it, return 1e30 and stop it afterwards. You may create
		700	and start a C<EV::prepare> watcher for this task.
354		701
355	It must return the next time to trigger, based on the passed time value	702	It must return the next time to trigger, based on the passed time value
356	(that is, the lowest time value larger than to the second argument). It	703	(that is, the lowest time value larger than or equal to to the second
357	will usually be called just before the callback will be triggered, but	704	argument). It will usually be called just before the callback will be
358	might be called at other times, too.	705	triggered, but might be called at other times, too.
359		706
360	This can be used to create very complex timers, such as a timer that	707	This can be used to create very complex timers, such as a timer that
361	triggers on each midnight, local time (actually 24 hours after the last	708	triggers on each midnight, local time (actually 24 hours after the last
362	midnight, to keep the example simple. If you know a way to do it correctly	709	midnight, to keep the example simple. If you know a way to do it correctly
363	in about the same space (without requiring elaborate modules), drop me a	710	in about the same space (without requiring elaborate modules), drop me a
…		…
377		724
378	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	725	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
379		726
380	=item $w->set ($at, $interval, $reschedule_cb)	727	=item $w->set ($at, $interval, $reschedule_cb)
381		728
382	Reconfigures the watcher, see the constructor above for details. Can be at	729	Reconfigures the watcher, see the constructor above for details. Can be called at
383	any time.	730	any time.
384		731
385	=item $w->again	732	=item $w->again
386		733
387	Simply stops and starts the watcher again.	734	Simply stops and starts the watcher again.
388		735
		736	=item $time = $w->at
		737
		738	Return the time that the watcher is expected to trigger next.
		739
		740	=back
		741
		742
		743	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		744
		745	=over 4
389		746
390	=item $w = EV::signal $signal, $callback	747	=item $w = EV::signal $signal, $callback
391		748
392	=item $w = EV::signal_ns $signal, $callback	749	=item $w = EV::signal_ns $signal, $callback
393		750
		751	=item $w = $loop->signal ($signal, $callback)
		752
		753	=item $w = $loop->signal_ns ($signal, $callback)
		754
394	Call the callback when $signal is received (the signal can be specified	755	Call the callback when $signal is received (the signal can be specified by
395	by number or by name, just as with kill or %SIG).	756	number or by name, just as with C<kill> or C<%SIG>).
		757
		758	Only one event loop can grab a given signal - attempting to grab the same
		759	signal from two EV loops will crash the program immediately or cause data
		760	corruption.
396		761
397	EV will grab the signal for the process (the kernel only allows one	762	EV will grab the signal for the process (the kernel only allows one
398	component to receive a signal at a time) when you start a signal watcher,	763	component to receive a signal at a time) when you start a signal watcher,
399	and removes it again when you stop it. Perl does the same when you	764	and removes it again when you stop it. Perl does the same when you
400	add/remove callbacks to %SIG, so watch out.	765	add/remove callbacks to C<%SIG>, so watch out.
401		766
402	You can have as many signal watchers per signal as you want.	767	You can have as many signal watchers per signal as you want.
403		768
404	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	769	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
405		770
406	=item $w->set ($signal)	771	=item $w->set ($signal)
407		772
408	Reconfigures the watcher, see the constructor above for details. Can be at	773	Reconfigures the watcher, see the constructor above for details. Can be
409	any time.	774	called at any time.
410		775
411	=item $current_signum = $w->signal	776	=item $current_signum = $w->signal
412		777
413	=item $old_signum = $w->signal ($new_signal)	778	=item $old_signum = $w->signal ($new_signal)
414		779
415	Returns the previously set signal (always as a number not name) and	780	Returns the previously set signal (always as a number not name) and
416	optionally set a new one.	781	optionally set a new one.
417		782
		783	=back
418		784
		785
		786	=head3 CHILD WATCHERS - watch out for process status changes
		787
		788	=over 4
		789
419	=item $w = EV::child $pid, $callback	790	=item $w = EV::child $pid, $trace, $callback
420		791
421	=item $w = EV::child_ns $pid, $callback	792	=item $w = EV::child_ns $pid, $trace, $callback
		793
		794	=item $w = $loop->child ($pid, $trace, $callback)
		795
		796	=item $w = $loop->child_ns ($pid, $trace, $callback)
422		797
423	Call the callback when a status change for pid C<$pid> (or any pid	798	Call the callback when a status change for pid C<$pid> (or any pid
424	if C<$pid> is 0) has been received. More precisely: when the process	799	if C<$pid> is 0) has been received (a status change happens when the
		800	process terminates or is killed, or, when trace is true, additionally when
		801	it is stopped or continued). More precisely: when the process receives
425	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	802	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
426	changed/zombie children and call the callback.	803	changed/zombie children and call the callback.
427		804
428	You can access both status and pid by using the C<rstatus> and C<rpid>	805	It is valid (and fully supported) to install a child watcher after a child
429	methods on the watcher object.	806	has exited but before the event loop has started its next iteration (for
		807	example, first you C<fork>, then the new child process might exit, and
		808	only then do you install a child watcher in the parent for the new pid).
430		809
		810	You can access both exit (or tracing) status and pid by using the
		811	C<rstatus> and C<rpid> methods on the watcher object.
		812
431	You can have as many pid watchers per pid as you want.	813	You can have as many pid watchers per pid as you want, they will all be
		814	called.
432		815
433	The C<child_ns> variant doesn't start (activate) the newly created watcher.	816	The C<child_ns> variant doesn't start (activate) the newly created watcher.
434		817
435	=item $w->set ($pid)	818	=item $w->set ($pid, $trace)
436		819
437	Reconfigures the watcher, see the constructor above for details. Can be at	820	Reconfigures the watcher, see the constructor above for details. Can be called at
438	any time.	821	any time.
439		822
440	=item $current_pid = $w->pid	823	=item $current_pid = $w->pid
441
442	=item $old_pid = $w->pid ($new_pid)
443		824
444	Returns the previously set process id and optionally set a new one.	825	Returns the previously set process id and optionally set a new one.
445		826
446	=item $exit_status = $w->rstatus	827	=item $exit_status = $w->rstatus
447		828
…		…
451	=item $pid = $w->rpid	832	=item $pid = $w->rpid
452		833
453	Return the pid of the awaited child (useful when you have installed a	834	Return the pid of the awaited child (useful when you have installed a
454	watcher for all pids).	835	watcher for all pids).
455		836
		837	=back
		838
		839
		840	=head3 STAT WATCHERS - did the file attributes just change?
		841
		842	=over 4
		843
		844	=item $w = EV::stat $path, $interval, $callback
		845
		846	=item $w = EV::stat_ns $path, $interval, $callback
		847
		848	=item $w = $loop->stat ($path, $interval, $callback)
		849
		850	=item $w = $loop->stat_ns ($path, $interval, $callback)
		851
		852	Call the callback when a file status change has been detected on
		853	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		854	to "path does not exist" is a status change like any other.
		855
		856	The C<$interval> is a recommended polling interval for systems where
		857	OS-supported change notifications don't exist or are not supported. If
		858	you use C<0> then an unspecified default is used (which is highly
		859	recommended!), which is to be expected to be around five seconds usually.
		860
		861	This watcher type is not meant for massive numbers of stat watchers,
		862	as even with OS-supported change notifications, this can be
		863	resource-intensive.
		864
		865	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		866
		867	=item ... = $w->stat
		868
		869	This call is very similar to the perl C<stat> built-in: It stats (using
		870	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		871	well as EV's idea of the current stat values) to the values found.
		872
		873	In scalar context, a boolean is return indicating success or failure of
		874	the stat. In list context, the same 13-value list as with stat is returned
		875	(except that the blksize and blocks fields are not reliable).
		876
		877	In the case of an error, errno is set to C<ENOENT> (regardless of the
		878	actual error value) and the C<nlink> value is forced to zero (if the stat
		879	was successful then nlink is guaranteed to be non-zero).
		880
		881	See also the next two entries for more info.
		882
		883	=item ... = $w->attr
		884
		885	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		886	the values most recently detected by EV. See the next entry for more info.
		887
		888	=item ... = $w->prev
		889
		890	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		891	the previous set of values, before the change.
		892
		893	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		894	to the values found I<before> a change was detected, while C<< $w->attr >>
		895	returns the values found leading to the change detection. The difference (if any)
		896	between C<prev> and C<attr> is what triggered the callback.
		897
		898	If you did something to the filesystem object and do not want to trigger
		899	yet another change, you can call C<stat> to update EV's idea of what the
		900	current attributes are.
		901
		902	=item $w->set ($path, $interval)
		903
		904	Reconfigures the watcher, see the constructor above for details. Can be
		905	called at any time.
		906
		907	=item $current_path = $w->path
		908
		909	=item $old_path = $w->path ($new_path)
		910
		911	Returns the previously set path and optionally set a new one.
		912
		913	=item $current_interval = $w->interval
		914
		915	=item $old_interval = $w->interval ($new_interval)
		916
		917	Returns the previously set interval and optionally set a new one. Can be
		918	used to query the actual interval used.
		919
		920	=back
		921
		922
		923	=head3 IDLE WATCHERS - when you've got nothing better to do...
		924
		925	=over 4
456		926
457	=item $w = EV::idle $callback	927	=item $w = EV::idle $callback
458		928
459	=item $w = EV::idle_ns $callback	929	=item $w = EV::idle_ns $callback
460		930
461	Call the callback when there are no pending io, timer/periodic, signal or	931	=item $w = $loop->idle ($callback)
462	child events, i.e. when the process is idle.	932
		933	=item $w = $loop->idle_ns ($callback)
		934
		935	Call the callback when there are no other pending watchers of the same or
		936	higher priority (excluding check, prepare and other idle watchers of the
		937	same or lower priority, of course). They are called idle watchers because
		938	when the watcher is the highest priority pending event in the process, the
		939	process is considered to be idle at that priority.
		940
		941	If you want a watcher that is only ever called when I<no> other events are
		942	outstanding you have to set the priority to C<EV::MINPRI>.
463		943
464	The process will not block as long as any idle watchers are active, and	944	The process will not block as long as any idle watchers are active, and
465	they will be called repeatedly until stopped.	945	they will be called repeatedly until stopped.
466		946
		947	For example, if you have idle watchers at priority C<0> and C<1>, and
		948	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		949	and the I/O watcher will always run when ready. Only when the idle watcher
		950	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		951	pending with the C<0>-priority idle watcher be invoked.
		952
467	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	953	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
468		954
		955	=back
		956
		957
		958	=head3 PREPARE WATCHERS - customise your event loop!
		959
		960	=over 4
469		961
470	=item $w = EV::prepare $callback	962	=item $w = EV::prepare $callback
471		963
472	=item $w = EV::prepare_ns $callback	964	=item $w = EV::prepare_ns $callback
		965
		966	=item $w = $loop->prepare ($callback)
		967
		968	=item $w = $loop->prepare_ns ($callback)
473		969
474	Call the callback just before the process would block. You can still	970	Call the callback just before the process would block. You can still
475	create/modify any watchers at this point.	971	create/modify any watchers at this point.
476		972
477	See the EV::check watcher, below, for explanations and an example.	973	See the EV::check watcher, below, for explanations and an example.
478		974
479	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	975	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
480		976
		977	=back
		978
		979
		980	=head3 CHECK WATCHERS - customise your event loop even more!
		981
		982	=over 4
481		983
482	=item $w = EV::check $callback	984	=item $w = EV::check $callback
483		985
484	=item $w = EV::check_ns $callback	986	=item $w = EV::check_ns $callback
		987
		988	=item $w = $loop->check ($callback)
		989
		990	=item $w = $loop->check_ns ($callback)
485		991
486	Call the callback just after the process wakes up again (after it has	992	Call the callback just after the process wakes up again (after it has
487	gathered events), but before any other callbacks have been invoked.	993	gathered events), but before any other callbacks have been invoked.
488		994
489	This is used to integrate other event-based software into the EV	995	This can be used to integrate other event-based software into the EV
490	mainloop: You register a prepare callback and in there, you create io and	996	mainloop: You register a prepare callback and in there, you create io and
491	timer watchers as required by the other software. Here is a real-world	997	timer watchers as required by the other software. Here is a real-world
492	example of integrating Net::SNMP (with some details left out):	998	example of integrating Net::SNMP (with some details left out):
493		999
494	our @snmp_watcher;	1000	our @snmp_watcher;
…		…
497	# do nothing unless active	1003	# do nothing unless active
498	$dispatcher->{_event_queue_h}	1004	$dispatcher->{_event_queue_h}
499	or return;	1005	or return;
500		1006
501	# make the dispatcher handle any outstanding stuff	1007	# make the dispatcher handle any outstanding stuff
		1008	... not shown
502		1009
503	# create an IO watcher for each and every socket	1010	# create an I/O watcher for each and every socket
504	@snmp_watcher = (	1011	@snmp_watcher = (
505	(map { EV::io $_, EV::READ, sub { } }	1012	(map { EV::io $_, EV::READ, sub { } }
506	keys %{ $dispatcher->{_descriptors} }),	1013	keys %{ $dispatcher->{_descriptors} }),
		1014
		1015	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1016	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1017	0, sub { },
507	);	1018	);
508
509	# if there are any timeouts, also create a timer
510	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
511	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
512	};	1019	};
513		1020
514	The callbacks are irrelevant, the only purpose of those watchers is	1021	The callbacks are irrelevant (and are not even being called), the
515	to wake up the process as soon as one of those events occurs (socket	1022	only purpose of those watchers is to wake up the process as soon as
516	readable, or timer timed out). The corresponding EV::check watcher will then	1023	one of those events occurs (socket readable, or timer timed out). The
517	clean up:	1024	corresponding EV::check watcher will then clean up:
518		1025
519	our $snmp_check = EV::check sub {	1026	our $snmp_check = EV::check sub {
520	# destroy all watchers	1027	# destroy all watchers
521	@snmp_watcher = ();	1028	@snmp_watcher = ();
522		1029
523	# make the dispatcher handle any new stuff	1030	# make the dispatcher handle any new stuff
		1031	... not shown
524	};	1032	};
525		1033
526	The callbacks of the created watchers will not be called as the watchers	1034	The callbacks of the created watchers will not be called as the watchers
527	are destroyed before this cna happen (remember EV::check gets called	1035	are destroyed before this can happen (remember EV::check gets called
528	first).	1036	first).
529		1037
530	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1038	The C<check_ns> variant doesn't start (activate) the newly created watcher.
531		1039
532	=back	1040	=item EV::CHECK constant issues
533		1041
		1042	Like all other watcher types, there is a bitmask constant for use in
		1043	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1044	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1045	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1046	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1047	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1048	safe side.
		1049
		1050	=back
		1051
		1052
		1053	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1054
		1055	Fork watchers are called when a C<fork ()> was detected. The invocation
		1056	is done before the event loop blocks next and before C<check> watchers
		1057	are being called, and only in the child after the fork.
		1058
		1059	=over 4
		1060
		1061	=item $w = EV::fork $callback
		1062
		1063	=item $w = EV::fork_ns $callback
		1064
		1065	=item $w = $loop->fork ($callback)
		1066
		1067	=item $w = $loop->fork_ns ($callback)
		1068
		1069	Call the callback before the event loop is resumed in the child process
		1070	after a fork.
		1071
		1072	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1073
		1074	=back
		1075
		1076
		1077	=head3 EMBED WATCHERS - when one backend isn't enough...
		1078
		1079	This is a rather advanced watcher type that lets you embed one event loop
		1080	into another (currently only IO events are supported in the embedded
		1081	loop, other types of watchers might be handled in a delayed or incorrect
		1082	fashion and must not be used).
		1083
		1084	See the libev documentation at
		1085	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1086	(locally installed as F<EV::libev>) for more details.
		1087
		1088	In short, this watcher is most useful on BSD systems without working
		1089	kqueue to still be able to handle a large number of sockets:
		1090
		1091	my $socket_loop;
		1092
		1093	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1094	if (
		1095	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1096	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1097	) {
		1098	# use kqueue for sockets
		1099	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1100	}
		1101
		1102	# use the default loop otherwise
		1103	$socket_loop \|\|= EV::default_loop;
		1104
		1105	=over 4
		1106
		1107	=item $w = EV::embed $otherloop[, $callback]
		1108
		1109	=item $w = EV::embed_ns $otherloop[, $callback]
		1110
		1111	=item $w = $loop->embed ($otherloop[, $callback])
		1112
		1113	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1114
		1115	Call the callback when the embedded event loop (C<$otherloop>) has any
		1116	I/O activity. The C<$callback> is optional: if it is missing, then the
		1117	embedded event loop will be managed automatically (which is recommended),
		1118	otherwise you have to invoke C<sweep> yourself.
		1119
		1120	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1121
		1122	=back
		1123
		1124	=head3 ASYNC WATCHERS - how to wake up another event loop
		1125
		1126	Async watchers are provided by EV, but have little use in perl directly,
		1127	as perl neither supports threads running in parallel nor direct access to
		1128	signal handlers or other contexts where they could be of value.
		1129
		1130	It is, however, possible to use them from the XS level.
		1131
		1132	Please see the libev documentation for further details.
		1133
		1134	=over 4
		1135
		1136	=item $w = EV::async $callback
		1137
		1138	=item $w = EV::async_ns $callback
		1139
		1140	=item $w->send
		1141
		1142	=item $bool = $w->async_pending
		1143
		1144	=back
		1145
		1146
		1147	=head1 PERL SIGNALS
		1148
		1149	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1150	with EV is as the same as any other C library: Perl-signals will only be
		1151	handled when Perl runs, which means your signal handler might be invoked
		1152	only the next time an event callback is invoked.
		1153
		1154	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1155	ensure proper operations with regards to other event watchers.
		1156
		1157	If you cannot do this for whatever reason, you can also force a watcher
		1158	to be called on every event loop iteration by installing a C<EV::check>
		1159	watcher:
		1160
		1161	my $async_check = EV::check sub { };
		1162
		1163	This ensures that perl gets into control for a short time to handle any
		1164	pending signals, and also ensures (slightly) slower overall operation.
		1165
534	=head1 THREADS	1166	=head1 ITHREADS
535		1167
536	Threads are not supported by this in any way. Perl pseudo-threads is evil	1168	Ithreads are not supported by this module in any way. Perl pseudo-threads
537	stuff and must die.	1169	is evil stuff and must die. Real threads as provided by Coro are fully
		1170	supported (and enhanced support is available via L<Coro::EV>).
		1171
		1172	=head1 FORK
		1173
		1174	Most of the "improved" event delivering mechanisms of modern operating
		1175	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1176	not supported and usually destructive). Libev makes it possible to work
		1177	around this by having a function that recreates the kernel state after
		1178	fork in the child.
		1179
		1180	On non-win32 platforms, this module requires the pthread_atfork
		1181	functionality to do this automatically for you. This function is quite
		1182	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1183	negligible, because everything the function currently does is set a flag
		1184	that is checked only when the event loop gets used the next time, so when
		1185	you do fork but not use EV, the overhead is minimal.
		1186
		1187	On win32, there is no notion of fork so all this doesn't apply, of course.
538		1188
539	=cut	1189	=cut
540		1190
541	our $DIED = sub {	1191	our $DIED = sub {
542	warn "EV: error in callback (ignoring): $@";	1192	warn "EV: error in callback (ignoring): $@";
543	};	1193	};
544		1194
545	default_loop	1195	default_loop
546	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';	1196	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
547		1197
548	1;	1198	1;
549		1199
550	=head1 SEE ALSO	1200	=head1 SEE ALSO
551		1201
552	L<EV::DNS>, L<EV::AnyEvent>.	1202	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1203	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1204	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1205	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1206	event-loop agnostic and portable event driven programming.
553		1207
554	=head1 AUTHOR	1208	=head1 AUTHOR
555		1209
556	Marc Lehmann <schmorp@schmorp.de>	1210	Marc Lehmann <schmorp@schmorp.de>
557	http://home.schmorp.de/	1211	http://home.schmorp.de/
558		1212
559	=cut	1213	=cut
560		1214

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Comparing EV/EV.pm (file contents): Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs. Revision 1.135 by root, Mon Dec 12 16:32:24 2011 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs.
Revision 1.135 by root, Mon Dec 12 16:32:24 2011 UTC