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

Comparing EV/EV.pm (file contents):
Revision 1.21 by root, Thu Nov 1 17:20:25 2007 UTC vs.
Revision 1.130 by root, Sun Oct 24 17:58:41 2010 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
		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.
52		64
53	=head1 DESCRIPTION	65	=head1 DESCRIPTION
54		66
55	This module provides an interface to libev	67	This module provides an interface to libev
56	(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.
57		116
58	=cut	117	=cut
59		118
60	package EV;	119	package EV;
61		120
62	use strict;	121	use common::sense;
63		122
64	BEGIN {	123	BEGIN {
65	our $VERSION = '0.1';	124	our $VERSION = '4.00';
66	use XSLoader;	125	use XSLoader;
67	XSLoader::load "EV", $VERSION;	126	XSLoader::load "EV", $VERSION;
68	}	127	}
69		128
70	@EV::Io::ISA =	129	@EV::IO::ISA =
71	@EV::Timer::ISA =	130	@EV::Timer::ISA =
72	@EV::Periodic::ISA =	131	@EV::Periodic::ISA =
73	@EV::Signal::ISA =	132	@EV::Signal::ISA =
		133	@EV::Child::ISA =
		134	@EV::Stat::ISA =
74	@EV::Idle::ISA =	135	@EV::Idle::ISA =
75	@EV::Prepare::ISA =	136	@EV::Prepare::ISA =
76	@EV::Check::ISA =	137	@EV::Check::ISA =
77	@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->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
78		207
79	=head1 BASIC INTERFACE	208	=head1 BASIC INTERFACE
80		209
81	=over 4	210	=over 4
82		211
83	=item $EV::DIED	212	=item $EV::DIED
84		213
85	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
86	throws an exception (with $@ containing thr error). The default prints an	215	throws an exception (with $@ containing the error). The default prints an
87	informative message and continues.	216	informative message and continues.
88		217
89	If this callback throws an exception it will be silently ignored.	218	If this callback throws an exception it will be silently ignored.
90		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
91	=item $time = EV::time	234	=item $time = EV::time
92		235
93	Returns the current time in (fractional) seconds since the epoch.	236	Returns the current time in (fractional) seconds since the epoch.
94		237
95	=item $time = EV::now	238	=item $time = EV::now
96		239
		240	=item $time = $loop->now
		241
97	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
98	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
99	usually faster then calling EV::time.	244	usually faster then calling EV::time.
100		245
101	=item $method = EV::ev_method	246	=item EV::now_update
102		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 = $loop->backend
		291
103	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	292	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
104	or EV::METHOD_EPOLL).	293	or EV::BACKEND_EPOLL).
105		294
106	=item EV::loop [$flags]	295	=item EV::loop [$flags]
107		296
		297	=item $loop->loop ([$flags])
		298
108	Begin checking for events and calling callbacks. It returns when a	299	Begin checking for events and calling callbacks. It returns when a
109	callback calls EV::loop_done.	300	callback calls EV::unloop.
110		301
111	The $flags argument can be one of the following:	302	The $flags argument can be one of the following:
112		303
113	0 as above	304	0 as above
114	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	305	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
115	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	306	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
116		307
117	=item EV::loop_done [$how]	308	=item EV::unloop [$how]
118		309
		310	=item $loop->unloop ([$how])
		311
119	When called with no arguments or an argument of 1, makes the innermost	312	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
120	call to EV::loop return.	313	innermost call to EV::loop return.
121		314
122	When called with an agrument of 2, all calls to EV::loop will return as	315	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
123	fast as possible.	316	fast as possible.
124		317
125	=back	318	=item $count = EV::loop_count
126		319
127	=head2 WATCHER	320	=item $count = $loop->loop_count
		321
		322	Return the number of times the event loop has polled for new
		323	events. Sometimes useful as a generation counter.
		324
		325	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		326
		327	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		328
		329	This function rolls together an I/O and a timer watcher for a single
		330	one-shot event without the need for managing a watcher object.
		331
		332	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		333	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		334	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		335	you do not want to wait for some I/O event, specify C<undef> for
		336	C<$fh_or_undef> and C<0> for C<$events>).
		337
		338	If timeout is C<undef> or negative, then there will be no
		339	timeout. Otherwise a EV::timer with this value will be started.
		340
		341	When an error occurs or either the timeout or I/O watcher triggers, then
		342	the callback will be called with the received event set (in general
		343	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		344	C<EV::WRITE> and C<EV::TIMER>).
		345
		346	EV::once doesn't return anything: the watchers stay active till either
		347	of them triggers, then they will be stopped and freed, and the callback
		348	invoked.
		349
		350	=item EV::feed_fd_event ($fd, $revents)
		351
		352	=item $loop->feed_fd_event ($fd, $revents)
		353
		354	Feed an event on a file descriptor into EV. EV will react to this call as
		355	if the readyness notifications specified by C<$revents> (a combination of
		356	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		357
		358	=item EV::feed_signal_event ($signal)
		359
		360	Feed a signal event into EV. EV will react to this call as if the signal
		361	specified by C<$signal> had occured.
		362
		363	=item EV::set_io_collect_interval $time
		364
		365	=item $loop->set_io_collect_interval ($time)
		366
		367	=item EV::set_timeout_collect_interval $time
		368
		369	=item $loop->set_timeout_collect_interval ($time)
		370
		371	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		372	wait interval for timer events. See the libev documentation at
		373	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		374	(locally installed as F<EV::libev>) for a more detailed discussion.
		375
		376	=item $count = EV::pending_count
		377
		378	=item $count = $loop->pending_count
		379
		380	Returns the number of currently pending watchers.
		381
		382	=item EV::invoke_pending
		383
		384	=item $loop->invoke_pending
		385
		386	Invoke all currently pending watchers.
		387
		388	=back
		389
		390
		391	=head1 WATCHER OBJECTS
128		392
129	A watcher is an object that gets created to record your interest in some	393	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	394	event. For instance, if you want to wait for STDIN to become readable, you
131	would create an EV::io watcher for that:	395	would create an EV::io watcher for that:
132		396
133	my $watcher = EV::io *STDIN, EV::READ, sub {	397	my $watcher = EV::io *STDIN, EV::READ, sub {
134	my ($watcher, $revents) = @_;	398	my ($watcher, $revents) = @_;
135	warn "yeah, STDIN should not be readable without blocking!\n"	399	warn "yeah, STDIN should now be readable without blocking!\n"
136	};	400	};
137		401
138	All watchers can be active (waiting for events) or inactive (paused). Only	402	All watchers can be active (waiting for events) or inactive (paused). Only
139	active watchers will have their callbacks invoked. All callbacks will be	403	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	404	called with at least two arguments: the watcher and a bitmask of received
141	events.	405	events.
142		406
143	Each watcher type has its associated bit in revents, so you can use the	407	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	408	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,	409	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	410	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	411	(which can set both EV::READ and EV::WRITE bits).
148	uses EV::TIMEOUT).
149		412
150	In the rare case where one wants to create a watcher but not start it at	413	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	414	the same time, each constructor has a variant with a trailing C<_ns> in
152	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.	415	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
153		416
154	Please note that a watcher will automatically be stopped when the watcher	417	Please note that a watcher will automatically be stopped when the watcher
155	object is returned, so you I<need> to keep the watcher objects returned by	418	object is destroyed, so you I<need> to keep the watcher objects returned by
156	the constructors.	419	the constructors.
157		420
158	=head2 WATCHER TYPES	421	Also, all methods changing some aspect of a watcher (->set, ->priority,
		422	->fh and so on) automatically stop and start it again if it is active,
		423	which means pending events get lost.
159		424
160	Now lets move to the existing watcher types and asociated methods.	425	=head2 COMMON WATCHER METHODS
161		426
162	The following methods are available for all watchers. Then followes a	427	This section lists methods common to all watchers.
163	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
164	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
165	any type-specific methods (if any).
166		428
167	=over 4	429	=over 4
168		430
169	=item $w->start	431	=item $w->start
170		432
…		…
174		436
175	=item $w->stop	437	=item $w->stop
176		438
177	Stop a watcher if it is active. Also clear any pending events (events that	439	Stop a watcher if it is active. Also clear any pending events (events that
178	have been received but that didn't yet result in a callback invocation),	440	have been received but that didn't yet result in a callback invocation),
179	regardless of wether the watcher was active or not.	441	regardless of whether the watcher was active or not.
180		442
181	=item $bool = $w->is_active	443	=item $bool = $w->is_active
182		444
183	Returns true if the watcher is active, false otherwise.	445	Returns true if the watcher is active, false otherwise.
184		446
		447	=item $current_data = $w->data
		448
		449	=item $old_data = $w->data ($new_data)
		450
		451	Queries a freely usable data scalar on the watcher and optionally changes
		452	it. This is a way to associate custom data with a watcher:
		453
		454	my $w = EV::timer 60, 0, sub {
		455	warn $_[0]->data;
		456	};
		457	$w->data ("print me!");
		458
185	=item $current_cb = $w->cb	459	=item $current_cb = $w->cb
186		460
187	=item $old_cb = $w->cb ($new_cb)	461	=item $old_cb = $w->cb ($new_cb)
188		462
189	Queries the callback on the watcher and optionally changes it. You cna do	463	Queries the callback on the watcher and optionally changes it. You can do
190	this at any time.	464	this at any time without the watcher restarting.
191		465
		466	=item $current_priority = $w->priority
		467
		468	=item $old_priority = $w->priority ($new_priority)
		469
		470	Queries the priority on the watcher and optionally changes it. Pending
		471	watchers with higher priority will be invoked first. The valid range of
		472	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		473	-2). If the priority is outside this range it will automatically be
		474	normalised to the nearest valid priority.
		475
		476	The default priority of any newly-created watcher is 0.
		477
		478	Note that the priority semantics have not yet been fleshed out and are
		479	subject to almost certain change.
		480
192	=item $w->trigger ($revents)	481	=item $w->invoke ($revents)
193		482
194	Call the callback now with the given event mask.	483	Call the callback now with the given event mask.
195		484
		485	=item $w->feed_event ($revents)
		486
		487	Feed some events on this watcher into EV. EV will react to this call as if
		488	the watcher had received the given C<$revents> mask.
		489
		490	=item $revents = $w->clear_pending
		491
		492	If the watcher is pending, this function clears its pending status and
		493	returns its C<$revents> bitset (as if its callback was invoked). If the
		494	watcher isn't pending it does nothing and returns C<0>.
		495
		496	=item $previous_state = $w->keepalive ($bool)
		497
		498	Normally, C<EV::loop> will return when there are no active watchers
		499	(which is a "deadlock" because no progress can be made anymore). This is
		500	convenient because it allows you to start your watchers (and your jobs),
		501	call C<EV::loop> once and when it returns you know that all your jobs are
		502	finished (or they forgot to register some watchers for their task :).
		503
		504	Sometimes, however, this gets in your way, for example when the module
		505	that calls C<EV::loop> (usually the main program) is not the same module
		506	as a long-living watcher (for example a DNS client module written by
		507	somebody else even). Then you might want any outstanding requests to be
		508	handled, but you would not want to keep C<EV::loop> from returning just
		509	because you happen to have this long-running UDP port watcher.
		510
		511	In this case you can clear the keepalive status, which means that even
		512	though your watcher is active, it won't keep C<EV::loop> from returning.
		513
		514	The initial value for keepalive is true (enabled), and you can change it
		515	any time.
		516
		517	Example: Register an I/O watcher for some UDP socket but do not keep the
		518	event loop from running just because of that watcher.
		519
		520	my $udp_socket = ...
		521	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		522	$udp_watcher->keepalive (0);
		523
		524	=item $loop = $w->loop
		525
		526	Return the loop that this watcher is attached to.
		527
		528	=back
		529
		530
		531	=head1 WATCHER TYPES
		532
		533	Each of the following subsections describes a single watcher type.
		534
		535	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		536
		537	=over 4
196		538
197	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	539	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
198		540
199	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	541	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
200		542
		543	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		544
		545	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		546
201	As long as the returned watcher object is alive, call the C<$callback>	547	As long as the returned watcher object is alive, call the C<$callback>
202	when the events specified in C<$eventmask>.	548	when at least one of events specified in C<$eventmask> occurs.
203		549
204	The $eventmask can be one or more of these constants ORed together:	550	The $eventmask can be one or more of these constants ORed together:
205		551
206	EV::READ wait until read() wouldn't block anymore	552	EV::READ wait until read() wouldn't block anymore
207	EV::WRITE wait until write() wouldn't block anymore	553	EV::WRITE wait until write() wouldn't block anymore
…		…
223		569
224	=item $old_eventmask = $w->events ($new_eventmask)	570	=item $old_eventmask = $w->events ($new_eventmask)
225		571
226	Returns the previously set event mask and optionally set a new one.	572	Returns the previously set event mask and optionally set a new one.
227		573
		574	=back
		575
		576
		577	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		578
		579	=over 4
228		580
229	=item $w = EV::timer $after, $repeat, $callback	581	=item $w = EV::timer $after, $repeat, $callback
230		582
231	=item $w = EV::timer_ns $after, $repeat, $callback	583	=item $w = EV::timer_ns $after, $repeat, $callback
232		584
233	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	585	=item $w = $loop->timer ($after, $repeat, $callback)
234	the timer will be restarted (with the $repeat value as $after) after the	586
235	callback returns.	587	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		588
		589	Calls the callback after C<$after> seconds (which may be fractional). If
		590	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		591	value as $after) after the callback returns.
236		592
237	This means that the callback would be called roughly after C<$after>	593	This means that the callback would be called roughly after C<$after>
238	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	594	seconds, and then every C<$repeat> seconds. The timer does his best not
239	callback processing is not taken into account, so the timer will slowly	595	to drift, but it will not invoke the timer more often then once per event
240	drift. If that isn't acceptable, look at EV::periodic.	596	loop iteration, and might drift in other cases. If that isn't acceptable,
		597	look at EV::periodic, which can provide long-term stable timers.
241		598
242	The timer is based on a monotonic clock, that is if somebody is sitting	599	The timer is based on a monotonic clock, that is, if somebody is sitting
243	in front of the machine while the timer is running and changes the system	600	in front of the machine while the timer is running and changes the system
244	clock, the timer will nevertheless run (roughly) the same time.	601	clock, the timer will nevertheless run (roughly) the same time.
245		602
246	The C<timer_ns> variant doesn't start (activate) the newly created watcher.	603	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
247		604
248	=item $w->set ($after, $repeat)	605	=item $w->set ($after, $repeat)
249		606
250	Reconfigures the watcher, see the constructor above for details. Can be at	607	Reconfigures the watcher, see the constructor above for details. Can be called at
251	any time.	608	any time.
252		609
253	=item $w->again	610	=item $w->again
254		611
255	Similar to the C<start> method, but has special semantics for repeating timers:	612	Similar to the C<start> method, but has special semantics for repeating timers:
		613
		614	If the timer is active and non-repeating, it will be stopped.
256		615
257	If the timer is active and repeating, reset the timeout to occur	616	If the timer is active and repeating, reset the timeout to occur
258	C<$repeat> seconds after now.	617	C<$repeat> seconds after now.
259		618
260	If the timer is active and non-repeating, it will be stopped.
261
262	If the timer is in active and repeating, start it.	619	If the timer is inactive and repeating, start it using the repeat value.
263		620
264	Otherwise do nothing.	621	Otherwise do nothing.
265		622
266	This behaviour is useful when you have a timeout for some IO	623	This behaviour is useful when you have a timeout for some IO
267	operation. You create a timer object with the same value for C<$after> and	624	operation. You create a timer object with the same value for C<$after> and
268	C<$repeat>, and then, in the read/write watcher, run the C<again> method	625	C<$repeat>, and then, in the read/write watcher, run the C<again> method
269	on the timeout.	626	on the timeout.
270		627
		628	=back
271		629
		630
		631	=head3 PERIODIC WATCHERS - to cron or not to cron?
		632
		633	=over 4
		634
272	=item $w = EV::periodic $at, $interval, $callback	635	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
273		636
274	=item $w = EV::periodic_ns $at, $interval, $callback	637	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
275		638
276	Similar to EV::timer, but the time is given as an absolute point in time	639	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
277	(C<$at>), plus an optional C<$interval>.
278		640
279	If the C<$interval> is zero, then the callback will be called at the time	641	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
280	C<$at> if that is in the future, or as soon as possible if it is in the
281	past. It will not automatically repeat.
282		642
283	If the C<$interval> is nonzero, then the watcher will always be scheduled	643	Similar to EV::timer, but is not based on relative timeouts but on
284	to time out at the next C<$at + N * $interval> time.	644	absolute times. Apart from creating "simple" timers that trigger "at" the
		645	specified time, it can also be used for non-drifting absolute timers and
		646	more complex, cron-like, setups that are not adversely affected by time
		647	jumps (i.e. when the system clock is changed by explicit date -s or other
		648	means such as ntpd). It is also the most complex watcher type in EV.
285		649
286	This can be used to schedule a callback to run at very regular intervals,	650	It has three distinct "modes":
287	as long as the processing time is less then the interval (otherwise	651
288	obviously events will be skipped).	652	=over 4
		653
		654	=item * absolute timer ($interval = $reschedule_cb = 0)
		655
		656	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		657	will not adjust when a time jump occurs, that is, if it is to be run
		658	at January 1st 2011 then it will run when the system time reaches or
		659	surpasses this time.
		660
		661	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		662
		663	In this mode the watcher will always be scheduled to time out at the
		664	next C<$at + N * $interval> time (for some integer N) and then repeat,
		665	regardless of any time jumps.
		666
		667	This can be used to create timers that do not drift with respect to system
		668	time:
		669
		670	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		671
		672	That doesn't mean there will always be 3600 seconds in between triggers,
		673	but only that the the clalback will be called when the system time shows a
		674	full hour (UTC).
289		675
290	Another way to think about it (for the mathematically inclined) is that	676	Another way to think about it (for the mathematically inclined) is that
291	EV::periodic will try to run the callback at the next possible time where	677	EV::periodic will try to run the callback in this mode at the next
292	C<$time = $at (mod $interval)>, regardless of any time jumps.	678	possible time where C<$time = $at (mod $interval)>, regardless of any time
		679	jumps.
293		680
294	This periodic timer is based on "wallclock time", that is, if the clock	681	=item * manual reschedule mode ($reschedule_cb = coderef)
295	changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at	682
296	the specified time. This means it will never drift (it might jitter, but	683	In this mode $interval and $at are both being ignored. Instead, each
297	it will not drift).	684	time the periodic watcher gets scheduled, the reschedule callback
		685	($reschedule_cb) will be called with the watcher as first, and the current
		686	time as second argument.
		687
		688	I<This callback MUST NOT stop or destroy this or any other periodic
		689	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		690	you need to stop it, return 1e30 and stop it afterwards. You may create
		691	and start a C<EV::prepare> watcher for this task.
		692
		693	It must return the next time to trigger, based on the passed time value
		694	(that is, the lowest time value larger than or equal to to the second
		695	argument). It will usually be called just before the callback will be
		696	triggered, but might be called at other times, too.
		697
		698	This can be used to create very complex timers, such as a timer that
		699	triggers on each midnight, local time (actually 24 hours after the last
		700	midnight, to keep the example simple. If you know a way to do it correctly
		701	in about the same space (without requiring elaborate modules), drop me a
		702	note :):
		703
		704	my $daily = EV::periodic 0, 0, sub {
		705	my ($w, $now) = @_;
		706
		707	use Time::Local ();
		708	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		709	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		710	}, sub {
		711	print "it's midnight or likely shortly after, now\n";
		712	};
		713
		714	=back
298		715
299	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	716	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
300		717
301	=item $w->set ($at, $interval)	718	=item $w->set ($at, $interval, $reschedule_cb)
302		719
303	Reconfigures the watcher, see the constructor above for details. Can be at	720	Reconfigures the watcher, see the constructor above for details. Can be called at
304	any time.	721	any time.
305		722
		723	=item $w->again
		724
		725	Simply stops and starts the watcher again.
		726
		727	=item $time = $w->at
		728
		729	Return the time that the watcher is expected to trigger next.
		730
		731	=back
		732
		733
		734	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		735
		736	=over 4
306		737
307	=item $w = EV::signal $signal, $callback	738	=item $w = EV::signal $signal, $callback
308		739
309	=item $w = EV::signal_ns $signal, $callback	740	=item $w = EV::signal_ns $signal, $callback
310		741
		742	=item $w = $loop->signal ($signal, $callback)
		743
		744	=item $w = $loop->signal_ns ($signal, $callback)
		745
311	Call the callback when $signal is received (the signal can be specified	746	Call the callback when $signal is received (the signal can be specified by
312	by number or by name, just as with kill or %SIG).	747	number or by name, just as with C<kill> or C<%SIG>).
		748
		749	Only one event loop can grab a given signal - attempting to grab the same
		750	signal from two EV loops will crash the program immediately or cause data
		751	corruption.
313		752
314	EV will grab the signal for the process (the kernel only allows one	753	EV will grab the signal for the process (the kernel only allows one
315	component to receive a signal at a time) when you start a signal watcher,	754	component to receive a signal at a time) when you start a signal watcher,
316	and removes it again when you stop it. Perl does the same when you	755	and removes it again when you stop it. Perl does the same when you
317	add/remove callbacks to %SIG, so watch out.	756	add/remove callbacks to C<%SIG>, so watch out.
318		757
319	You can have as many signal watchers per signal as you want.	758	You can have as many signal watchers per signal as you want.
320		759
321	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	760	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
322		761
323	=item $w->set ($signal)	762	=item $w->set ($signal)
324		763
325	Reconfigures the watcher, see the constructor above for details. Can be at	764	Reconfigures the watcher, see the constructor above for details. Can be
		765	called at any time.
		766
		767	=item $current_signum = $w->signal
		768
		769	=item $old_signum = $w->signal ($new_signal)
		770
		771	Returns the previously set signal (always as a number not name) and
		772	optionally set a new one.
		773
		774	=back
		775
		776
		777	=head3 CHILD WATCHERS - watch out for process status changes
		778
		779	=over 4
		780
		781	=item $w = EV::child $pid, $trace, $callback
		782
		783	=item $w = EV::child_ns $pid, $trace, $callback
		784
		785	=item $w = $loop->child ($pid, $trace, $callback)
		786
		787	=item $w = $loop->child_ns ($pid, $trace, $callback)
		788
		789	Call the callback when a status change for pid C<$pid> (or any pid
		790	if C<$pid> is 0) has been received (a status change happens when the
		791	process terminates or is killed, or, when trace is true, additionally when
		792	it is stopped or continued). More precisely: when the process receives
		793	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		794	changed/zombie children and call the callback.
		795
		796	It is valid (and fully supported) to install a child watcher after a child
		797	has exited but before the event loop has started its next iteration (for
		798	example, first you C<fork>, then the new child process might exit, and
		799	only then do you install a child watcher in the parent for the new pid).
		800
		801	You can access both exit (or tracing) status and pid by using the
		802	C<rstatus> and C<rpid> methods on the watcher object.
		803
		804	You can have as many pid watchers per pid as you want, they will all be
		805	called.
		806
		807	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		808
		809	=item $w->set ($pid, $trace)
		810
		811	Reconfigures the watcher, see the constructor above for details. Can be called at
326	any time.	812	any time.
327		813
		814	=item $current_pid = $w->pid
328		815
329	=item $w = EV::child $pid, $callback	816	Returns the previously set process id and optionally set a new one.
330		817
331	=item $w = EV::child_ns $pid, $callback	818	=item $exit_status = $w->rstatus
332		819
333	Call the callback when a status change for pid C<$pid> (or any pid	820	Return the exit/wait status (as returned by waitpid, see the waitpid entry
334	if C<$pid> is 0) has been received. More precisely: when the process	821	in perlfunc).
335	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
336	changed/zombie children and call the callback.
337		822
338	Unlike all other callbacks, this callback will be called with an	823	=item $pid = $w->rpid
339	additional third argument which is the exit status. See the C<waitpid>
340	function for details.
341		824
342	You can have as many pid watchers per pid as you want.	825	Return the pid of the awaited child (useful when you have installed a
		826	watcher for all pids).
343		827
		828	=back
		829
		830
		831	=head3 STAT WATCHERS - did the file attributes just change?
		832
		833	=over 4
		834
		835	=item $w = EV::stat $path, $interval, $callback
		836
		837	=item $w = EV::stat_ns $path, $interval, $callback
		838
		839	=item $w = $loop->stat ($path, $interval, $callback)
		840
		841	=item $w = $loop->stat_ns ($path, $interval, $callback)
		842
		843	Call the callback when a file status change has been detected on
		844	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		845	to "path does not exist" is a status change like any other.
		846
		847	The C<$interval> is a recommended polling interval for systems where
		848	OS-supported change notifications don't exist or are not supported. If
		849	you use C<0> then an unspecified default is used (which is highly
		850	recommended!), which is to be expected to be around five seconds usually.
		851
		852	This watcher type is not meant for massive numbers of stat watchers,
		853	as even with OS-supported change notifications, this can be
		854	resource-intensive.
		855
344	The C<child_ns> variant doesn't start (activate) the newly created watcher.	856	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
345		857
346	=item $w->set ($pid)	858	=item ... = $w->stat
347		859
		860	This call is very similar to the perl C<stat> built-in: It stats (using
		861	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		862	well as EV's idea of the current stat values) to the values found.
		863
		864	In scalar context, a boolean is return indicating success or failure of
		865	the stat. In list context, the same 13-value list as with stat is returned
		866	(except that the blksize and blocks fields are not reliable).
		867
		868	In the case of an error, errno is set to C<ENOENT> (regardless of the
		869	actual error value) and the C<nlink> value is forced to zero (if the stat
		870	was successful then nlink is guaranteed to be non-zero).
		871
		872	See also the next two entries for more info.
		873
		874	=item ... = $w->attr
		875
		876	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		877	the values most recently detected by EV. See the next entry for more info.
		878
		879	=item ... = $w->prev
		880
		881	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		882	the previous set of values, before the change.
		883
		884	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		885	to the values found I<before> a change was detected, while C<< $w->attr >>
		886	returns the values found leading to the change detection. The difference (if any)
		887	between C<prev> and C<attr> is what triggered the callback.
		888
		889	If you did something to the filesystem object and do not want to trigger
		890	yet another change, you can call C<stat> to update EV's idea of what the
		891	current attributes are.
		892
		893	=item $w->set ($path, $interval)
		894
348	Reconfigures the watcher, see the constructor above for details. Can be at	895	Reconfigures the watcher, see the constructor above for details. Can be
349	any time.	896	called at any time.
350		897
		898	=item $current_path = $w->path
		899
		900	=item $old_path = $w->path ($new_path)
		901
		902	Returns the previously set path and optionally set a new one.
		903
		904	=item $current_interval = $w->interval
		905
		906	=item $old_interval = $w->interval ($new_interval)
		907
		908	Returns the previously set interval and optionally set a new one. Can be
		909	used to query the actual interval used.
		910
		911	=back
		912
		913
		914	=head3 IDLE WATCHERS - when you've got nothing better to do...
		915
		916	=over 4
351		917
352	=item $w = EV::idle $callback	918	=item $w = EV::idle $callback
353		919
354	=item $w = EV::idle_ns $callback	920	=item $w = EV::idle_ns $callback
355		921
356	Call the callback when there are no pending io, timer/periodic, signal or	922	=item $w = $loop->idle ($callback)
357	child events, i.e. when the process is idle.	923
		924	=item $w = $loop->idle_ns ($callback)
		925
		926	Call the callback when there are no other pending watchers of the same or
		927	higher priority (excluding check, prepare and other idle watchers of the
		928	same or lower priority, of course). They are called idle watchers because
		929	when the watcher is the highest priority pending event in the process, the
		930	process is considered to be idle at that priority.
		931
		932	If you want a watcher that is only ever called when I<no> other events are
		933	outstanding you have to set the priority to C<EV::MINPRI>.
358		934
359	The process will not block as long as any idle watchers are active, and	935	The process will not block as long as any idle watchers are active, and
360	they will be called repeatedly until stopped.	936	they will be called repeatedly until stopped.
361		937
		938	For example, if you have idle watchers at priority C<0> and C<1>, and
		939	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		940	and the I/O watcher will always run when ready. Only when the idle watcher
		941	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		942	pending with the C<0>-priority idle watcher be invoked.
		943
362	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	944	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
363		945
		946	=back
		947
		948
		949	=head3 PREPARE WATCHERS - customise your event loop!
		950
		951	=over 4
364		952
365	=item $w = EV::prepare $callback	953	=item $w = EV::prepare $callback
366		954
367	=item $w = EV::prepare_ns $callback	955	=item $w = EV::prepare_ns $callback
		956
		957	=item $w = $loop->prepare ($callback)
		958
		959	=item $w = $loop->prepare_ns ($callback)
368		960
369	Call the callback just before the process would block. You can still	961	Call the callback just before the process would block. You can still
370	create/modify any watchers at this point.	962	create/modify any watchers at this point.
371		963
372	See the EV::check watcher, below, for explanations and an example.	964	See the EV::check watcher, below, for explanations and an example.
373		965
374	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	966	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
375		967
		968	=back
		969
		970
		971	=head3 CHECK WATCHERS - customise your event loop even more!
		972
		973	=over 4
376		974
377	=item $w = EV::check $callback	975	=item $w = EV::check $callback
378		976
379	=item $w = EV::check_ns $callback	977	=item $w = EV::check_ns $callback
		978
		979	=item $w = $loop->check ($callback)
		980
		981	=item $w = $loop->check_ns ($callback)
380		982
381	Call the callback just after the process wakes up again (after it has	983	Call the callback just after the process wakes up again (after it has
382	gathered events), but before any other callbacks have been invoked.	984	gathered events), but before any other callbacks have been invoked.
383		985
384	This is used to integrate other event-based software into the EV	986	This can be used to integrate other event-based software into the EV
385	mainloop: You register a prepare callback and in there, you create io and	987	mainloop: You register a prepare callback and in there, you create io and
386	timer watchers as required by the other software. Here is a real-world	988	timer watchers as required by the other software. Here is a real-world
387	example of integrating Net::SNMP (with some details left out):	989	example of integrating Net::SNMP (with some details left out):
388		990
389	our @snmp_watcher;	991	our @snmp_watcher;
…		…
392	# do nothing unless active	994	# do nothing unless active
393	$dispatcher->{_event_queue_h}	995	$dispatcher->{_event_queue_h}
394	or return;	996	or return;
395		997
396	# make the dispatcher handle any outstanding stuff	998	# make the dispatcher handle any outstanding stuff
		999	... not shown
397		1000
398	# create an IO watcher for each and every socket	1001	# create an I/O watcher for each and every socket
399	@snmp_watcher = (	1002	@snmp_watcher = (
400	(map { EV::io $_, EV::READ, sub { } }	1003	(map { EV::io $_, EV::READ, sub { } }
401	keys %{ $dispatcher->{_descriptors} }),	1004	keys %{ $dispatcher->{_descriptors} }),
		1005
		1006	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1007	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1008	0, sub { },
402	);	1009	);
403
404	# if there are any timeouts, also create a timer
405	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
406	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
407	};	1010	};
408		1011
409	The callbacks are irrelevant, the only purpose of those watchers is	1012	The callbacks are irrelevant (and are not even being called), the
410	to wake up the process as soon as one of those events occurs (socket	1013	only purpose of those watchers is to wake up the process as soon as
411	readable, or timer timed out). The corresponding EV::check watcher will then	1014	one of those events occurs (socket readable, or timer timed out). The
412	clean up:	1015	corresponding EV::check watcher will then clean up:
413		1016
414	our $snmp_check = EV::check sub {	1017	our $snmp_check = EV::check sub {
415	# destroy all watchers	1018	# destroy all watchers
416	@snmp_watcher = ();	1019	@snmp_watcher = ();
417		1020
418	# make the dispatcher handle any new stuff	1021	# make the dispatcher handle any new stuff
		1022	... not shown
419	};	1023	};
420		1024
421	The callbacks of the created watchers will not be called as the watchers	1025	The callbacks of the created watchers will not be called as the watchers
422	are destroyed before this cna happen (remember EV::check gets called	1026	are destroyed before this can happen (remember EV::check gets called
423	first).	1027	first).
424		1028
425	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1029	The C<check_ns> variant doesn't start (activate) the newly created watcher.
426		1030
427	=back	1031	=item EV::CHECK constant issues
428		1032
		1033	Like all other watcher types, there is a bitmask constant for use in
		1034	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1035	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1036	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1037	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1038	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1039	safe side.
		1040
		1041	=back
		1042
		1043
		1044	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1045
		1046	Fork watchers are called when a C<fork ()> was detected. The invocation
		1047	is done before the event loop blocks next and before C<check> watchers
		1048	are being called, and only in the child after the fork.
		1049
		1050	=over 4
		1051
		1052	=item $w = EV::fork $callback
		1053
		1054	=item $w = EV::fork_ns $callback
		1055
		1056	=item $w = $loop->fork ($callback)
		1057
		1058	=item $w = $loop->fork_ns ($callback)
		1059
		1060	Call the callback before the event loop is resumed in the child process
		1061	after a fork.
		1062
		1063	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1064
		1065	=back
		1066
		1067
		1068	=head3 EMBED WATCHERS - when one backend isn't enough...
		1069
		1070	This is a rather advanced watcher type that lets you embed one event loop
		1071	into another (currently only IO events are supported in the embedded
		1072	loop, other types of watchers might be handled in a delayed or incorrect
		1073	fashion and must not be used).
		1074
		1075	See the libev documentation at
		1076	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1077	(locally installed as F<EV::libev>) for more details.
		1078
		1079	In short, this watcher is most useful on BSD systems without working
		1080	kqueue to still be able to handle a large number of sockets:
		1081
		1082	my $socket_loop;
		1083
		1084	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1085	if (
		1086	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1087	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1088	) {
		1089	# use kqueue for sockets
		1090	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1091	}
		1092
		1093	# use the default loop otherwise
		1094	$socket_loop \|\|= EV::default_loop;
		1095
		1096	=over 4
		1097
		1098	=item $w = EV::embed $otherloop[, $callback]
		1099
		1100	=item $w = EV::embed_ns $otherloop[, $callback]
		1101
		1102	=item $w = $loop->embed ($otherloop[, $callback])
		1103
		1104	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1105
		1106	Call the callback when the embedded event loop (C<$otherloop>) has any
		1107	I/O activity. The C<$callback> is optional: if it is missing, then the
		1108	embedded event loop will be managed automatically (which is recommended),
		1109	otherwise you have to invoke C<sweep> yourself.
		1110
		1111	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1112
		1113	=back
		1114
		1115	=head3 ASYNC WATCHERS - how to wake up another event loop
		1116
		1117	Async watchers are provided by EV, but have little use in perl directly,
		1118	as perl neither supports threads running in parallel nor direct access to
		1119	signal handlers or other contexts where they could be of value.
		1120
		1121	It is, however, possible to use them from the XS level.
		1122
		1123	Please see the libev documentation for further details.
		1124
		1125	=over 4
		1126
		1127	=item $w = EV::async $callback
		1128
		1129	=item $w = EV::async_ns $callback
		1130
		1131	=item $w->send
		1132
		1133	=item $bool = $w->async_pending
		1134
		1135	=back
		1136
		1137
		1138	=head1 PERL SIGNALS
		1139
		1140	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1141	with EV is as the same as any other C library: Perl-signals will only be
		1142	handled when Perl runs, which means your signal handler might be invoked
		1143	only the next time an event callback is invoked.
		1144
		1145	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1146	ensure proper operations with regards to other event watchers.
		1147
		1148	If you cannot do this for whatever reason, you can also force a watcher
		1149	to be called on every event loop iteration by installing a C<EV::check>
		1150	watcher:
		1151
		1152	my $async_check = EV::check sub { };
		1153
		1154	This ensures that perl gets into control for a short time to handle any
		1155	pending signals, and also ensures (slightly) slower overall operation.
		1156
429	=head1 THREADS	1157	=head1 ITHREADS
430		1158
431	Threads are not supported by this in any way. Perl pseudo-threads is evil	1159	Ithreads are not supported by this module in any way. Perl pseudo-threads
432	stuff and must die.	1160	is evil stuff and must die. Real threads as provided by Coro are fully
		1161	supported (and enhanced support is available via L<Coro::EV>).
		1162
		1163	=head1 FORK
		1164
		1165	Most of the "improved" event delivering mechanisms of modern operating
		1166	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1167	not supported and usually destructive). Libev makes it possible to work
		1168	around this by having a function that recreates the kernel state after
		1169	fork in the child.
		1170
		1171	On non-win32 platforms, this module requires the pthread_atfork
		1172	functionality to do this automatically for you. This function is quite
		1173	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1174	negligible, because everything the function currently does is set a flag
		1175	that is checked only when the event loop gets used the next time, so when
		1176	you do fork but not use EV, the overhead is minimal.
		1177
		1178	On win32, there is no notion of fork so all this doesn't apply, of course.
433		1179
434	=cut	1180	=cut
435		1181
436	our $DIED = sub {	1182	our $DIED = sub {
437	warn "EV: error in callback (ignoring): $@";	1183	warn "EV: error in callback (ignoring): $@";
438	};	1184	};
439		1185
440	init;	1186	default_loop
441		1187	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
442	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
443		1188
444	1;	1189	1;
445		1190
446	=head1 SEE ALSO	1191	=head1 SEE ALSO
447		1192
448	L<EV::DNS>, L<EV::AnyEvent>.	1193	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1194	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1195	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1196	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1197	event-loop agnostic and portable event driven programming.
449		1198
450	=head1 AUTHOR	1199	=head1 AUTHOR
451		1200
452	Marc Lehmann <schmorp@schmorp.de>	1201	Marc Lehmann <schmorp@schmorp.de>
453	http://home.schmorp.de/	1202	http://home.schmorp.de/
454		1203
455	=cut	1204	=cut
456		1205

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Comparing EV/EV.pm (file contents): Revision 1.21 by root, Thu Nov 1 17:20:25 2007 UTC vs. Revision 1.130 by root, Sun Oct 24 17:58:41 2010 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.21 by root, Thu Nov 1 17:20:25 2007 UTC vs.
Revision 1.130 by root, Sun Oct 24 17:58:41 2010 UTC