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

Comparing EV/EV.pm (file contents):
Revision 1.22 by root, Fri Nov 2 11:02:22 2007 UTC vs.
Revision 1.142 by root, Sat Mar 8 15:51:23 2014 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::run; # 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::run EV::RUN_ONCE; # 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::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.
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 = '4.16';
66	use XSLoader;	125	use XSLoader;
		126	local $^W = 0; # avoid spurious warning
67	XSLoader::load "EV", $VERSION;	127	XSLoader::load "EV", $VERSION;
68	}	128	}
69		129
70	@EV::Io::ISA =	130	@EV::IO::ISA =
71	@EV::Timer::ISA =	131	@EV::Timer::ISA =
72	@EV::Periodic::ISA =	132	@EV::Periodic::ISA =
73	@EV::Signal::ISA =	133	@EV::Signal::ISA =
		134	@EV::Child::ISA =
		135	@EV::Stat::ISA =
74	@EV::Idle::ISA =	136	@EV::Idle::ISA =
75	@EV::Prepare::ISA =	137	@EV::Prepare::ISA =
76	@EV::Check::ISA =	138	@EV::Check::ISA =
77	@EV::Child::ISA = "EV::Watcher";	139	@EV::Embed::ISA =
		140	@EV::Fork::ISA =
		141	@EV::Async::ISA =
		142	"EV::Watcher";
		143
		144	@EV::Loop::Default::ISA = "EV::Loop";
		145
		146	=head1 EVENT LOOPS
		147
		148	EV supports multiple event loops: There is a single "default event loop"
		149	that can handle everything including signals and child watchers, and any
		150	number of "dynamic event loops" that can use different backends (with
		151	various limitations), but no child and signal watchers.
		152
		153	You do not have to do anything to create the default event loop: When
		154	the module is loaded a suitable backend is selected on the premise of
		155	selecting a working backend (which for example rules out kqueue on most
		156	BSDs). Modules should, unless they have "special needs" always use the
		157	default loop as this is fastest (perl-wise), best supported by other
		158	modules (e.g. AnyEvent or Coro) and most portable event loop.
		159
		160	For specific programs you can create additional event loops dynamically.
		161
		162	If you want to take advantage of kqueue (which often works properly for
		163	sockets only) even though the default loop doesn't enable it, you can
		164	I<embed> a kqueue loop into the default loop: running the default loop
		165	will then also service the kqueue loop to some extent. See the example in
		166	the section about embed watchers for an example on how to achieve that.
		167
		168	=over 4
		169
		170	=item $loop = new EV::Loop [$flags]
		171
		172	Create a new event loop as per the specified flags. Please refer to
		173	the C<ev_loop_new ()> function description in the libev documentation
		174	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		175	or locally-installed as F<EV::libev> manpage) for more info.
		176
		177	The loop will automatically be destroyed when it is no longer referenced
		178	by any watcher and the loop object goes out of scope.
		179
		180	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		181	is recommended, as only the default event loop is protected by this
		182	module. If you I<are> embedding this loop in the default loop, this is not
		183	necessary, as C<EV::embed> automatically does the right thing on fork.
		184
		185	=item $loop->loop_fork
		186
		187	Must be called after a fork in the child, before entering or continuing
		188	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		189	this function automatically, at some performance loss (refer to the libev
		190	documentation).
		191
		192	=item $loop->verify
		193
		194	Calls C<ev_verify> to make internal consistency checks (for debugging
		195	libev) and abort the program if any data structures were found to be
		196	corrupted.
		197
		198	=item $loop = EV::default_loop [$flags]
		199
		200	Return the default loop (which is a singleton object). Since this module
		201	already creates the default loop with default flags, specifying flags here
		202	will not have any effect unless you destroy the default loop first, which
		203	isn't supported. So in short: don't do it, and if you break it, you get to
		204	keep the pieces.
		205
		206	=back
		207
78		208
79	=head1 BASIC INTERFACE	209	=head1 BASIC INTERFACE
80		210
81	=over 4	211	=over 4
82		212
83	=item $EV::DIED	213	=item $EV::DIED
84		214
85	Must contain a reference to a function that is called when a callback	215	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	216	throws an exception (with $@ containing the error). The default prints an
87	informative message and continues.	217	informative message and continues.
88		218
89	If this callback throws an exception it will be silently ignored.	219	If this callback throws an exception it will be silently ignored.
90		220
		221	=item $flags = EV::supported_backends
		222
		223	=item $flags = EV::recommended_backends
		224
		225	=item $flags = EV::embeddable_backends
		226
		227	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		228	instance of EV, the set of recommended backends (supposed to be good) for
		229	this platform and the set of embeddable backends (see EMBED WATCHERS).
		230
		231	=item EV::sleep $seconds
		232
		233	Block the process for the given number of (fractional) seconds.
		234
91	=item $time = EV::time	235	=item $time = EV::time
92		236
93	Returns the current time in (fractional) seconds since the epoch.	237	Returns the current time in (fractional) seconds since the epoch.
94		238
95	=item $time = EV::now	239	=item $time = EV::now
96		240
		241	=item $time = $loop->now
		242
97	Returns the time the last event loop iteration has been started. This	243	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	244	is the time that (relative) timers are based on, and referring to it is
99	usually faster then calling EV::time.	245	usually faster then calling EV::time.
100		246
101	=item $method = EV::ev_method	247	=item EV::now_update
102		248
		249	=item $loop->now_update
		250
		251	Establishes the current time by querying the kernel, updating the time
		252	returned by C<EV::now> in the progress. This is a costly operation and
		253	is usually done automatically within C<EV::loop>.
		254
		255	This function is rarely useful, but when some event callback runs for a
		256	very long time without entering the event loop, updating libev's idea of
		257	the current time is a good idea.
		258
		259	=item EV::suspend
		260
		261	=item $loop->suspend
		262
		263	=item EV::resume
		264
		265	=item $loop->resume
		266
		267	These two functions suspend and resume a loop, for use when the loop is
		268	not used for a while and timeouts should not be processed.
		269
		270	A typical use case would be an interactive program such as a game: When
		271	the user presses C<^Z> to suspend the game and resumes it an hour later it
		272	would be best to handle timeouts as if no time had actually passed while
		273	the program was suspended. This can be achieved by calling C<suspend>
		274	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		275	C<resume> directly afterwards to resume timer processing.
		276
		277	Effectively, all C<timer> watchers will be delayed by the time spend
		278	between C<suspend> and C<resume>, and all C<periodic> watchers
		279	will be rescheduled (that is, they will lose any events that would have
		280	occured while suspended).
		281
		282	After calling C<suspend> you B<must not> call I<any> function on the given
		283	loop other than C<resume>, and you B<must not> call C<resume>
		284	without a previous call to C<suspend>.
		285
		286	Calling C<suspend>/C<resume> has the side effect of updating the event
		287	loop time (see C<now_update>).
		288
		289	=item $backend = EV::backend
		290
		291	=item $backend = $loop->backend
		292
103	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	293	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
104	or EV::METHOD_EPOLL).	294	or EV::BACKEND_EPOLL).
105		295
106	=item EV::loop [$flags]	296	=item $active = EV::run [$flags]
		297
		298	=item $active = $loop->run ([$flags])
107		299
108	Begin checking for events and calling callbacks. It returns when a	300	Begin checking for events and calling callbacks. It returns when a
109	callback calls EV::loop_done.	301	callback calls EV::unloop or the flasg are nonzero (in which case the
		302	return value is true) or when there are no active watchers which reference
		303	the loop (keepalive is true), in which case the return value will be
		304	false. The returnv alue can generally be interpreted as "if true, there is
		305	more work left to do".
110		306
111	The $flags argument can be one of the following:	307	The $flags argument can be one of the following:
112		308
113	0 as above	309	0 as above
114	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	310	EV::RUN_ONCE block at most once (wait, but do not loop)
115	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	311	EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
116		312
117	=item EV::loop_done [$how]	313	=item EV::break [$how]
118		314
		315	=item $loop->break ([$how])
		316
119	When called with no arguments or an argument of 1, makes the innermost	317	When called with no arguments or an argument of EV::BREAK_ONE, makes the
120	call to EV::loop return.	318	innermost call to EV::loop return.
121		319
122	When called with an agrument of 2, all calls to EV::loop will return as	320	When called with an argument of EV::BREAK_ALL, all calls to EV::loop will
123	fast as possible.	321	return as fast as possible.
124		322
125	=back	323	When called with an argument of EV::BREAK_CANCEL, any pending break will
		324	be cancelled.
126		325
127	=head2 WATCHER	326	=item $count = EV::iteration
		327
		328	=item $count = $loop->iteration
		329
		330	Return the number of times the event loop has polled for new
		331	events. Sometimes useful as a generation counter.
		332
		333	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		334
		335	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		336
		337	This function rolls together an I/O and a timer watcher for a single
		338	one-shot event without the need for managing a watcher object.
		339
		340	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		341	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		342	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		343	you do not want to wait for some I/O event, specify C<undef> for
		344	C<$fh_or_undef> and C<0> for C<$events>).
		345
		346	If timeout is C<undef> or negative, then there will be no
		347	timeout. Otherwise a EV::timer with this value will be started.
		348
		349	When an error occurs or either the timeout or I/O watcher triggers, then
		350	the callback will be called with the received event set (in general
		351	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		352	C<EV::WRITE> and C<EV::TIMER>).
		353
		354	EV::once doesn't return anything: the watchers stay active till either
		355	of them triggers, then they will be stopped and freed, and the callback
		356	invoked.
		357
		358	=item EV::feed_fd_event $fd, $revents
		359
		360	=item $loop->feed_fd_event ($fd, $revents)
		361
		362	Feed an event on a file descriptor into EV. EV will react to this call as
		363	if the readyness notifications specified by C<$revents> (a combination of
		364	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		365
		366	=item EV::feed_signal_event $signal
		367
		368	Feed a signal event into the default loop. EV will react to this call as
		369	if the signal specified by C<$signal> had occured.
		370
		371	=item EV::feed_signal $signal
		372
		373	Feed a signal event into EV - unlike C<EV::feed_signal_event>, this works
		374	regardless of which loop has registered the signal, and is mainly useful
		375	fro custom signal implementations.
		376
		377	=item EV::set_io_collect_interval $time
		378
		379	=item $loop->set_io_collect_interval ($time)
		380
		381	=item EV::set_timeout_collect_interval $time
		382
		383	=item $loop->set_timeout_collect_interval ($time)
		384
		385	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		386	wait interval for timer events. See the libev documentation at
		387	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		388	(locally installed as F<EV::libev>) for a more detailed discussion.
		389
		390	=item $count = EV::pending_count
		391
		392	=item $count = $loop->pending_count
		393
		394	Returns the number of currently pending watchers.
		395
		396	=item EV::invoke_pending
		397
		398	=item $loop->invoke_pending
		399
		400	Invoke all currently pending watchers.
		401
		402	=back
		403
		404
		405	=head1 WATCHER OBJECTS
128		406
129	A watcher is an object that gets created to record your interest in some	407	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	408	event. For instance, if you want to wait for STDIN to become readable, you
131	would create an EV::io watcher for that:	409	would create an EV::io watcher for that:
132		410
133	my $watcher = EV::io *STDIN, EV::READ, sub {	411	my $watcher = EV::io *STDIN, EV::READ, sub {
134	my ($watcher, $revents) = @_;	412	my ($watcher, $revents) = @_;
135	warn "yeah, STDIN should not be readable without blocking!\n"	413	warn "yeah, STDIN should now be readable without blocking!\n"
136	};	414	};
137		415
138	All watchers can be active (waiting for events) or inactive (paused). Only	416	All watchers can be active (waiting for events) or inactive (paused). Only
139	active watchers will have their callbacks invoked. All callbacks will be	417	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	418	called with at least two arguments: the watcher and a bitmask of received
141	events.	419	events.
142		420
143	Each watcher type has its associated bit in revents, so you can use the	421	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	422	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,	423	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	424	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	425	(which can set both EV::READ and EV::WRITE bits).
148	uses EV::TIMEOUT).
149		426
150	In the rare case where one wants to create a watcher but not start it at	427	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	428	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.	429	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
153		430
154	Please note that a watcher will automatically be stopped when the watcher	431	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	432	object is destroyed, so you I<need> to keep the watcher objects returned by
156	the constructors.	433	the constructors.
157		434
158	=head2 WATCHER TYPES	435	Also, all methods changing some aspect of a watcher (->set, ->priority,
		436	->fh and so on) automatically stop and start it again if it is active,
		437	which means pending events get lost.
159		438
160	Now lets move to the existing watcher types and asociated methods.	439	=head2 COMMON WATCHER METHODS
161		440
162	The following methods are available for all watchers. Then followes a	441	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		442
167	=over 4	443	=over 4
168		444
169	=item $w->start	445	=item $w->start
170		446
…		…
174		450
175	=item $w->stop	451	=item $w->stop
176		452
177	Stop a watcher if it is active. Also clear any pending events (events that	453	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),	454	have been received but that didn't yet result in a callback invocation),
179	regardless of wether the watcher was active or not.	455	regardless of whether the watcher was active or not.
180		456
181	=item $bool = $w->is_active	457	=item $bool = $w->is_active
182		458
183	Returns true if the watcher is active, false otherwise.	459	Returns true if the watcher is active, false otherwise.
184		460
		461	=item $current_data = $w->data
		462
		463	=item $old_data = $w->data ($new_data)
		464
		465	Queries a freely usable data scalar on the watcher and optionally changes
		466	it. This is a way to associate custom data with a watcher:
		467
		468	my $w = EV::timer 60, 0, sub {
		469	warn $_[0]->data;
		470	};
		471	$w->data ("print me!");
		472
185	=item $current_cb = $w->cb	473	=item $current_cb = $w->cb
186		474
187	=item $old_cb = $w->cb ($new_cb)	475	=item $old_cb = $w->cb ($new_cb)
188		476
189	Queries the callback on the watcher and optionally changes it. You cna do	477	Queries the callback on the watcher and optionally changes it. You can do
190	this at any time.	478	this at any time without the watcher restarting.
191		479
		480	=item $current_priority = $w->priority
		481
		482	=item $old_priority = $w->priority ($new_priority)
		483
		484	Queries the priority on the watcher and optionally changes it. Pending
		485	watchers with higher priority will be invoked first. The valid range of
		486	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		487	-2). If the priority is outside this range it will automatically be
		488	normalised to the nearest valid priority.
		489
		490	The default priority of any newly-created watcher is 0.
		491
		492	Note that the priority semantics have not yet been fleshed out and are
		493	subject to almost certain change.
		494
192	=item $w->trigger ($revents)	495	=item $w->invoke ($revents)
193		496
194	Call the callback now with the given event mask.	497	Call the callback now with the given event mask.
195		498
		499	=item $w->feed_event ($revents)
		500
		501	Feed some events on this watcher into EV. EV will react to this call as if
		502	the watcher had received the given C<$revents> mask.
		503
		504	=item $revents = $w->clear_pending
		505
		506	If the watcher is pending, this function clears its pending status and
		507	returns its C<$revents> bitset (as if its callback was invoked). If the
		508	watcher isn't pending it does nothing and returns C<0>.
		509
		510	=item $previous_state = $w->keepalive ($bool)
		511
		512	Normally, C<EV::loop> will return when there are no active watchers
		513	(which is a "deadlock" because no progress can be made anymore). This is
		514	convenient because it allows you to start your watchers (and your jobs),
		515	call C<EV::loop> once and when it returns you know that all your jobs are
		516	finished (or they forgot to register some watchers for their task :).
		517
		518	Sometimes, however, this gets in your way, for example when the module
		519	that calls C<EV::loop> (usually the main program) is not the same module
		520	as a long-living watcher (for example a DNS client module written by
		521	somebody else even). Then you might want any outstanding requests to be
		522	handled, but you would not want to keep C<EV::loop> from returning just
		523	because you happen to have this long-running UDP port watcher.
		524
		525	In this case you can clear the keepalive status, which means that even
		526	though your watcher is active, it won't keep C<EV::loop> from returning.
		527
		528	The initial value for keepalive is true (enabled), and you can change it
		529	any time.
		530
		531	Example: Register an I/O watcher for some UDP socket but do not keep the
		532	event loop from running just because of that watcher.
		533
		534	my $udp_socket = ...
		535	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		536	$udp_watcher->keepalive (0);
		537
		538	=item $loop = $w->loop
		539
		540	Return the loop that this watcher is attached to.
		541
		542	=back
		543
		544
		545	=head1 WATCHER TYPES
		546
		547	Each of the following subsections describes a single watcher type.
		548
		549	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		550
		551	=over 4
196		552
197	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	553	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
198		554
199	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	555	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
200		556
		557	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		558
		559	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		560
201	As long as the returned watcher object is alive, call the C<$callback>	561	As long as the returned watcher object is alive, call the C<$callback>
202	when the events specified in C<$eventmask>.	562	when at least one of events specified in C<$eventmask> occurs.
203		563
204	The $eventmask can be one or more of these constants ORed together:	564	The $eventmask can be one or more of these constants ORed together:
205		565
206	EV::READ wait until read() wouldn't block anymore	566	EV::READ wait until read() wouldn't block anymore
207	EV::WRITE wait until write() wouldn't block anymore	567	EV::WRITE wait until write() wouldn't block anymore
…		…
223		583
224	=item $old_eventmask = $w->events ($new_eventmask)	584	=item $old_eventmask = $w->events ($new_eventmask)
225		585
226	Returns the previously set event mask and optionally set a new one.	586	Returns the previously set event mask and optionally set a new one.
227		587
		588	=back
		589
		590
		591	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		592
		593	=over 4
228		594
229	=item $w = EV::timer $after, $repeat, $callback	595	=item $w = EV::timer $after, $repeat, $callback
230		596
231	=item $w = EV::timer_ns $after, $repeat, $callback	597	=item $w = EV::timer_ns $after, $repeat, $callback
232		598
233	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	599	=item $w = $loop->timer ($after, $repeat, $callback)
234	the timer will be restarted (with the $repeat value as $after) after the	600
235	callback returns.	601	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		602
		603	Calls the callback after C<$after> seconds (which may be fractional). If
		604	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		605	value as $after) after the callback returns.
236		606
237	This means that the callback would be called roughly after C<$after>	607	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	608	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	609	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.	610	loop iteration, and might drift in other cases. If that isn't acceptable,
		611	look at EV::periodic, which can provide long-term stable timers.
241		612
242	The timer is based on a monotonic clock, that is if somebody is sitting	613	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	614	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.	615	clock, the timer will nevertheless run (roughly) the same time.
245		616
246	The C<timer_ns> variant doesn't start (activate) the newly created watcher.	617	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
247		618
248	=item $w->set ($after, $repeat)	619	=item $w->set ($after, $repeat)
249		620
250	Reconfigures the watcher, see the constructor above for details. Can be at	621	Reconfigures the watcher, see the constructor above for details. Can be called at
251	any time.	622	any time.
252		623
253	=item $w->again	624	=item $w->again
254		625
255	Similar to the C<start> method, but has special semantics for repeating timers:	626	Similar to the C<start> method, but has special semantics for repeating timers:
		627
		628	If the timer is active and non-repeating, it will be stopped.
256		629
257	If the timer is active and repeating, reset the timeout to occur	630	If the timer is active and repeating, reset the timeout to occur
258	C<$repeat> seconds after now.	631	C<$repeat> seconds after now.
259		632
260	If the timer is active and non-repeating, it will be stopped.
261
262	If the timer is in active and repeating, start it.	633	If the timer is inactive and repeating, start it using the repeat value.
263		634
264	Otherwise do nothing.	635	Otherwise do nothing.
265		636
266	This behaviour is useful when you have a timeout for some IO	637	This behaviour is useful when you have a timeout for some IO
267	operation. You create a timer object with the same value for C<$after> and	638	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	639	C<$repeat>, and then, in the read/write watcher, run the C<again> method
269	on the timeout.	640	on the timeout.
270		641
		642	=back
271		643
		644
		645	=head3 PERIODIC WATCHERS - to cron or not to cron?
		646
		647	=over 4
		648
272	=item $w = EV::periodic $at, $interval, $callback	649	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
273		650
274	=item $w = EV::periodic_ns $at, $interval, $callback	651	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
275		652
276	Similar to EV::timer, but the time is given as an absolute point in time	653	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
277	(C<$at>), plus an optional C<$interval>.
278		654
279	If the C<$interval> is zero, then the callback will be called at the time	655	=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		656
283	If the C<$interval> is nonzero, then the watcher will always be scheduled	657	Similar to EV::timer, but is not based on relative timeouts but on
284	to time out at the next C<$at + N * $interval> time.	658	absolute times. Apart from creating "simple" timers that trigger "at" the
		659	specified time, it can also be used for non-drifting absolute timers and
		660	more complex, cron-like, setups that are not adversely affected by time
		661	jumps (i.e. when the system clock is changed by explicit date -s or other
		662	means such as ntpd). It is also the most complex watcher type in EV.
285		663
286	This can be used to schedule a callback to run at very regular intervals,	664	It has three distinct "modes":
287	as long as the processing time is less then the interval (otherwise	665
288	obviously events will be skipped).	666	=over 4
		667
		668	=item * absolute timer ($interval = $reschedule_cb = 0)
		669
		670	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		671	will not adjust when a time jump occurs, that is, if it is to be run
		672	at January 1st 2011 then it will run when the system time reaches or
		673	surpasses this time.
		674
		675	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		676
		677	In this mode the watcher will always be scheduled to time out at the
		678	next C<$at + N * $interval> time (for some integer N) and then repeat,
		679	regardless of any time jumps.
		680
		681	This can be used to create timers that do not drift with respect to system
		682	time:
		683
		684	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		685
		686	That doesn't mean there will always be 3600 seconds in between triggers,
		687	but only that the the callback will be called when the system time shows a
		688	full hour (UTC).
289		689
290	Another way to think about it (for the mathematically inclined) is that	690	Another way to think about it (for the mathematically inclined) is that
291	EV::periodic will try to run the callback at the next possible time where	691	EV::periodic will try to run the callback in this mode at the next
292	C<$time = $at (mod $interval)>, regardless of any time jumps.	692	possible time where C<$time = $at (mod $interval)>, regardless of any time
		693	jumps.
293		694
294	This periodic timer is based on "wallclock time", that is, if the clock	695	=item * manual reschedule mode ($reschedule_cb = coderef)
295	changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at	696
296	the specified time. This means it will never drift (it might jitter, but	697	In this mode $interval and $at are both being ignored. Instead, each
297	it will not drift).	698	time the periodic watcher gets scheduled, the reschedule callback
		699	($reschedule_cb) will be called with the watcher as first, and the current
		700	time as second argument.
		701
		702	I<This callback MUST NOT stop or destroy this or any other periodic
		703	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		704	you need to stop it, return 1e30 and stop it afterwards. You may create
		705	and start a C<EV::prepare> watcher for this task.
		706
		707	It must return the next time to trigger, based on the passed time value
		708	(that is, the lowest time value larger than or equal to to the second
		709	argument). It will usually be called just before the callback will be
		710	triggered, but might be called at other times, too.
		711
		712	This can be used to create very complex timers, such as a timer that
		713	triggers on each midnight, local time (actually 24 hours after the last
		714	midnight, to keep the example simple. If you know a way to do it correctly
		715	in about the same space (without requiring elaborate modules), drop me a
		716	note :):
		717
		718	my $daily = EV::periodic 0, 0, sub {
		719	my ($w, $now) = @_;
		720
		721	use Time::Local ();
		722	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		723	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		724	}, sub {
		725	print "it's midnight or likely shortly after, now\n";
		726	};
		727
		728	=back
298		729
299	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	730	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
300		731
301	=item $w->set ($at, $interval)	732	=item $w->set ($at, $interval, $reschedule_cb)
302		733
303	Reconfigures the watcher, see the constructor above for details. Can be at	734	Reconfigures the watcher, see the constructor above for details. Can be called at
304	any time.	735	any time.
305		736
		737	=item $w->again
		738
		739	Simply stops and starts the watcher again.
		740
		741	=item $time = $w->at
		742
		743	Return the time that the watcher is expected to trigger next.
		744
		745	=back
		746
		747
		748	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		749
		750	=over 4
306		751
307	=item $w = EV::signal $signal, $callback	752	=item $w = EV::signal $signal, $callback
308		753
309	=item $w = EV::signal_ns $signal, $callback	754	=item $w = EV::signal_ns $signal, $callback
310		755
		756	=item $w = $loop->signal ($signal, $callback)
		757
		758	=item $w = $loop->signal_ns ($signal, $callback)
		759
311	Call the callback when $signal is received (the signal can be specified	760	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).	761	number or by name, just as with C<kill> or C<%SIG>).
		762
		763	Only one event loop can grab a given signal - attempting to grab the same
		764	signal from two EV loops will crash the program immediately or cause data
		765	corruption.
313		766
314	EV will grab the signal for the process (the kernel only allows one	767	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,	768	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	769	and removes it again when you stop it. Perl does the same when you
317	add/remove callbacks to %SIG, so watch out.	770	add/remove callbacks to C<%SIG>, so watch out.
318		771
319	You can have as many signal watchers per signal as you want.	772	You can have as many signal watchers per signal as you want.
320		773
321	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	774	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
322		775
323	=item $w->set ($signal)	776	=item $w->set ($signal)
324		777
325	Reconfigures the watcher, see the constructor above for details. Can be at	778	Reconfigures the watcher, see the constructor above for details. Can be
326	any time.	779	called at any time.
327		780
328	=item $current_signum = $w->signal	781	=item $current_signum = $w->signal
329		782
330	=item $old_signum = $w->signal ($new_signal)	783	=item $old_signum = $w->signal ($new_signal)
331		784
332	Returns the previously set signal (always as a number not name) and	785	Returns the previously set signal (always as a number not name) and
333	optionally set a new one.	786	optionally set a new one.
334		787
		788	=back
335		789
		790
		791	=head3 CHILD WATCHERS - watch out for process status changes
		792
		793	=over 4
		794
336	=item $w = EV::child $pid, $callback	795	=item $w = EV::child $pid, $trace, $callback
337		796
338	=item $w = EV::child_ns $pid, $callback	797	=item $w = EV::child_ns $pid, $trace, $callback
		798
		799	=item $w = $loop->child ($pid, $trace, $callback)
		800
		801	=item $w = $loop->child_ns ($pid, $trace, $callback)
339		802
340	Call the callback when a status change for pid C<$pid> (or any pid	803	Call the callback when a status change for pid C<$pid> (or any pid
341	if C<$pid> is 0) has been received. More precisely: when the process	804	if C<$pid> is 0) has been received (a status change happens when the
		805	process terminates or is killed, or, when trace is true, additionally when
		806	it is stopped or continued). More precisely: when the process receives
342	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	807	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
343	changed/zombie children and call the callback.	808	changed/zombie children and call the callback.
344		809
345	Unlike all other callbacks, this callback will be called with an	810	It is valid (and fully supported) to install a child watcher after a child
346	additional third argument which is the exit status. See the C<waitpid>	811	has exited but before the event loop has started its next iteration (for
347	function for details.	812	example, first you C<fork>, then the new child process might exit, and
		813	only then do you install a child watcher in the parent for the new pid).
348		814
		815	You can access both exit (or tracing) status and pid by using the
		816	C<rstatus> and C<rpid> methods on the watcher object.
		817
349	You can have as many pid watchers per pid as you want.	818	You can have as many pid watchers per pid as you want, they will all be
		819	called.
350		820
351	The C<child_ns> variant doesn't start (activate) the newly created watcher.	821	The C<child_ns> variant doesn't start (activate) the newly created watcher.
352		822
353	=item $w->set ($pid)	823	=item $w->set ($pid, $trace)
354		824
355	Reconfigures the watcher, see the constructor above for details. Can be at	825	Reconfigures the watcher, see the constructor above for details. Can be called at
356	any time.	826	any time.
357		827
358	=item $current_pid = $w->pid	828	=item $current_pid = $w->pid
359		829
360	=item $old_pid = $w->pid ($new_pid)
361
362	Returns the previously set process id and optionally set a new one.	830	Returns the previously set process id and optionally set a new one.
363		831
		832	=item $exit_status = $w->rstatus
		833
		834	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		835	in perlfunc).
		836
		837	=item $pid = $w->rpid
		838
		839	Return the pid of the awaited child (useful when you have installed a
		840	watcher for all pids).
		841
		842	=back
		843
		844
		845	=head3 STAT WATCHERS - did the file attributes just change?
		846
		847	=over 4
		848
		849	=item $w = EV::stat $path, $interval, $callback
		850
		851	=item $w = EV::stat_ns $path, $interval, $callback
		852
		853	=item $w = $loop->stat ($path, $interval, $callback)
		854
		855	=item $w = $loop->stat_ns ($path, $interval, $callback)
		856
		857	Call the callback when a file status change has been detected on
		858	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		859	to "path does not exist" is a status change like any other.
		860
		861	The C<$interval> is a recommended polling interval for systems where
		862	OS-supported change notifications don't exist or are not supported. If
		863	you use C<0> then an unspecified default is used (which is highly
		864	recommended!), which is to be expected to be around five seconds usually.
		865
		866	This watcher type is not meant for massive numbers of stat watchers,
		867	as even with OS-supported change notifications, this can be
		868	resource-intensive.
		869
		870	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		871
		872	=item ... = $w->stat
		873
		874	This call is very similar to the perl C<stat> built-in: It stats (using
		875	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		876	well as EV's idea of the current stat values) to the values found.
		877
		878	In scalar context, a boolean is return indicating success or failure of
		879	the stat. In list context, the same 13-value list as with stat is returned
		880	(except that the blksize and blocks fields are not reliable).
		881
		882	In the case of an error, errno is set to C<ENOENT> (regardless of the
		883	actual error value) and the C<nlink> value is forced to zero (if the stat
		884	was successful then nlink is guaranteed to be non-zero).
		885
		886	See also the next two entries for more info.
		887
		888	=item ... = $w->attr
		889
		890	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		891	the values most recently detected by EV. See the next entry for more info.
		892
		893	=item ... = $w->prev
		894
		895	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		896	the previous set of values, before the change.
		897
		898	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		899	to the values found I<before> a change was detected, while C<< $w->attr >>
		900	returns the values found leading to the change detection. The difference (if any)
		901	between C<prev> and C<attr> is what triggered the callback.
		902
		903	If you did something to the filesystem object and do not want to trigger
		904	yet another change, you can call C<stat> to update EV's idea of what the
		905	current attributes are.
		906
		907	=item $w->set ($path, $interval)
		908
		909	Reconfigures the watcher, see the constructor above for details. Can be
		910	called at any time.
		911
		912	=item $current_path = $w->path
		913
		914	=item $old_path = $w->path ($new_path)
		915
		916	Returns the previously set path and optionally set a new one.
		917
		918	=item $current_interval = $w->interval
		919
		920	=item $old_interval = $w->interval ($new_interval)
		921
		922	Returns the previously set interval and optionally set a new one. Can be
		923	used to query the actual interval used.
		924
		925	=back
		926
		927
		928	=head3 IDLE WATCHERS - when you've got nothing better to do...
		929
		930	=over 4
364		931
365	=item $w = EV::idle $callback	932	=item $w = EV::idle $callback
366		933
367	=item $w = EV::idle_ns $callback	934	=item $w = EV::idle_ns $callback
368		935
369	Call the callback when there are no pending io, timer/periodic, signal or	936	=item $w = $loop->idle ($callback)
370	child events, i.e. when the process is idle.	937
		938	=item $w = $loop->idle_ns ($callback)
		939
		940	Call the callback when there are no other pending watchers of the same or
		941	higher priority (excluding check, prepare and other idle watchers of the
		942	same or lower priority, of course). They are called idle watchers because
		943	when the watcher is the highest priority pending event in the process, the
		944	process is considered to be idle at that priority.
		945
		946	If you want a watcher that is only ever called when I<no> other events are
		947	outstanding you have to set the priority to C<EV::MINPRI>.
371		948
372	The process will not block as long as any idle watchers are active, and	949	The process will not block as long as any idle watchers are active, and
373	they will be called repeatedly until stopped.	950	they will be called repeatedly until stopped.
374		951
		952	For example, if you have idle watchers at priority C<0> and C<1>, and
		953	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		954	and the I/O watcher will always run when ready. Only when the idle watcher
		955	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		956	pending with the C<0>-priority idle watcher be invoked.
		957
375	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	958	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
376		959
		960	=back
		961
		962
		963	=head3 PREPARE WATCHERS - customise your event loop!
		964
		965	=over 4
377		966
378	=item $w = EV::prepare $callback	967	=item $w = EV::prepare $callback
379		968
380	=item $w = EV::prepare_ns $callback	969	=item $w = EV::prepare_ns $callback
		970
		971	=item $w = $loop->prepare ($callback)
		972
		973	=item $w = $loop->prepare_ns ($callback)
381		974
382	Call the callback just before the process would block. You can still	975	Call the callback just before the process would block. You can still
383	create/modify any watchers at this point.	976	create/modify any watchers at this point.
384		977
385	See the EV::check watcher, below, for explanations and an example.	978	See the EV::check watcher, below, for explanations and an example.
386		979
387	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	980	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
388		981
		982	=back
		983
		984
		985	=head3 CHECK WATCHERS - customise your event loop even more!
		986
		987	=over 4
389		988
390	=item $w = EV::check $callback	989	=item $w = EV::check $callback
391		990
392	=item $w = EV::check_ns $callback	991	=item $w = EV::check_ns $callback
		992
		993	=item $w = $loop->check ($callback)
		994
		995	=item $w = $loop->check_ns ($callback)
393		996
394	Call the callback just after the process wakes up again (after it has	997	Call the callback just after the process wakes up again (after it has
395	gathered events), but before any other callbacks have been invoked.	998	gathered events), but before any other callbacks have been invoked.
396		999
397	This is used to integrate other event-based software into the EV	1000	This can be used to integrate other event-based software into the EV
398	mainloop: You register a prepare callback and in there, you create io and	1001	mainloop: You register a prepare callback and in there, you create io and
399	timer watchers as required by the other software. Here is a real-world	1002	timer watchers as required by the other software. Here is a real-world
400	example of integrating Net::SNMP (with some details left out):	1003	example of integrating Net::SNMP (with some details left out):
401		1004
402	our @snmp_watcher;	1005	our @snmp_watcher;
…		…
405	# do nothing unless active	1008	# do nothing unless active
406	$dispatcher->{_event_queue_h}	1009	$dispatcher->{_event_queue_h}
407	or return;	1010	or return;
408		1011
409	# make the dispatcher handle any outstanding stuff	1012	# make the dispatcher handle any outstanding stuff
		1013	... not shown
410		1014
411	# create an IO watcher for each and every socket	1015	# create an I/O watcher for each and every socket
412	@snmp_watcher = (	1016	@snmp_watcher = (
413	(map { EV::io $_, EV::READ, sub { } }	1017	(map { EV::io $_, EV::READ, sub { } }
414	keys %{ $dispatcher->{_descriptors} }),	1018	keys %{ $dispatcher->{_descriptors} }),
		1019
		1020	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1021	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1022	0, sub { },
415	);	1023	);
416
417	# if there are any timeouts, also create a timer
418	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
419	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
420	};	1024	};
421		1025
422	The callbacks are irrelevant, the only purpose of those watchers is	1026	The callbacks are irrelevant (and are not even being called), the
423	to wake up the process as soon as one of those events occurs (socket	1027	only purpose of those watchers is to wake up the process as soon as
424	readable, or timer timed out). The corresponding EV::check watcher will then	1028	one of those events occurs (socket readable, or timer timed out). The
425	clean up:	1029	corresponding EV::check watcher will then clean up:
426		1030
427	our $snmp_check = EV::check sub {	1031	our $snmp_check = EV::check sub {
428	# destroy all watchers	1032	# destroy all watchers
429	@snmp_watcher = ();	1033	@snmp_watcher = ();
430		1034
431	# make the dispatcher handle any new stuff	1035	# make the dispatcher handle any new stuff
		1036	... not shown
432	};	1037	};
433		1038
434	The callbacks of the created watchers will not be called as the watchers	1039	The callbacks of the created watchers will not be called as the watchers
435	are destroyed before this cna happen (remember EV::check gets called	1040	are destroyed before this can happen (remember EV::check gets called
436	first).	1041	first).
437		1042
438	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1043	The C<check_ns> variant doesn't start (activate) the newly created watcher.
439		1044
440	=back	1045	=item EV::CHECK constant issues
441		1046
		1047	Like all other watcher types, there is a bitmask constant for use in
		1048	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1049	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1050	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1051	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1052	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1053	safe side.
		1054
		1055	=back
		1056
		1057
		1058	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1059
		1060	Fork watchers are called when a C<fork ()> was detected. The invocation
		1061	is done before the event loop blocks next and before C<check> watchers
		1062	are being called, and only in the child after the fork.
		1063
		1064	=over 4
		1065
		1066	=item $w = EV::fork $callback
		1067
		1068	=item $w = EV::fork_ns $callback
		1069
		1070	=item $w = $loop->fork ($callback)
		1071
		1072	=item $w = $loop->fork_ns ($callback)
		1073
		1074	Call the callback before the event loop is resumed in the child process
		1075	after a fork.
		1076
		1077	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1078
		1079	=back
		1080
		1081
		1082	=head3 EMBED WATCHERS - when one backend isn't enough...
		1083
		1084	This is a rather advanced watcher type that lets you embed one event loop
		1085	into another (currently only IO events are supported in the embedded
		1086	loop, other types of watchers might be handled in a delayed or incorrect
		1087	fashion and must not be used).
		1088
		1089	See the libev documentation at
		1090	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1091	(locally installed as F<EV::libev>) for more details.
		1092
		1093	In short, this watcher is most useful on BSD systems without working
		1094	kqueue to still be able to handle a large number of sockets:
		1095
		1096	my $socket_loop;
		1097
		1098	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1099	if (
		1100	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1101	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1102	) {
		1103	# use kqueue for sockets
		1104	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1105	}
		1106
		1107	# use the default loop otherwise
		1108	$socket_loop \|\|= EV::default_loop;
		1109
		1110	=over 4
		1111
		1112	=item $w = EV::embed $otherloop[, $callback]
		1113
		1114	=item $w = EV::embed_ns $otherloop[, $callback]
		1115
		1116	=item $w = $loop->embed ($otherloop[, $callback])
		1117
		1118	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1119
		1120	Call the callback when the embedded event loop (C<$otherloop>) has any
		1121	I/O activity. The C<$callback> is optional: if it is missing, then the
		1122	embedded event loop will be managed automatically (which is recommended),
		1123	otherwise you have to invoke C<sweep> yourself.
		1124
		1125	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1126
		1127	=back
		1128
		1129	=head3 ASYNC WATCHERS - how to wake up another event loop
		1130
		1131	Async watchers are provided by EV, but have little use in perl directly,
		1132	as perl neither supports threads running in parallel nor direct access to
		1133	signal handlers or other contexts where they could be of value.
		1134
		1135	It is, however, possible to use them from the XS level.
		1136
		1137	Please see the libev documentation for further details.
		1138
		1139	=over 4
		1140
		1141	=item $w = EV::async $callback
		1142
		1143	=item $w = EV::async_ns $callback
		1144
		1145	=item $w = $loop->async ($callback)
		1146
		1147	=item $w = $loop->async_ns ($callback)
		1148
		1149	=item $w->send
		1150
		1151	=item $bool = $w->async_pending
		1152
		1153	=back
		1154
		1155	=head3 CLEANUP WATCHERS - how to clean up when the event loop goes away
		1156
		1157	Cleanup watchers are not supported on the Perl level, they can only be
		1158	used via XS currently.
		1159
		1160
		1161	=head1 PERL SIGNALS
		1162
		1163	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1164	with EV is as the same as any other C library: Perl-signals will only be
		1165	handled when Perl runs, which means your signal handler might be invoked
		1166	only the next time an event callback is invoked.
		1167
		1168	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1169	ensure proper operations with regards to other event watchers.
		1170
		1171	If you cannot do this for whatever reason, you can also force a watcher
		1172	to be called on every event loop iteration by installing a C<EV::check>
		1173	watcher:
		1174
		1175	my $async_check = EV::check sub { };
		1176
		1177	This ensures that perl gets into control for a short time to handle any
		1178	pending signals, and also ensures (slightly) slower overall operation.
		1179
442	=head1 THREADS	1180	=head1 ITHREADS
443		1181
444	Threads are not supported by this in any way. Perl pseudo-threads is evil	1182	Ithreads are not supported by this module in any way. Perl pseudo-threads
445	stuff and must die.	1183	is evil stuff and must die. Real threads as provided by Coro are fully
		1184	supported (and enhanced support is available via L<Coro::EV>).
		1185
		1186	=head1 FORK
		1187
		1188	Most of the "improved" event delivering mechanisms of modern operating
		1189	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1190	not supported and usually destructive). Libev makes it possible to work
		1191	around this by having a function that recreates the kernel state after
		1192	fork in the child.
		1193
		1194	On non-win32 platforms, this module requires the pthread_atfork
		1195	functionality to do this automatically for you. This function is quite
		1196	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1197	negligible, because everything the function currently does is set a flag
		1198	that is checked only when the event loop gets used the next time, so when
		1199	you do fork but not use EV, the overhead is minimal.
		1200
		1201	On win32, there is no notion of fork so all this doesn't apply, of course.
446		1202
447	=cut	1203	=cut
448		1204
449	our $DIED = sub {	1205	our $DIED = sub {
450	warn "EV: error in callback (ignoring): $@";	1206	warn "EV: error in callback (ignoring): $@";
451	};	1207	};
452		1208
453	init;	1209	default_loop
454		1210	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
455	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
456		1211
457	1;	1212	1;
458		1213
459	=head1 SEE ALSO	1214	=head1 SEE ALSO
460		1215
461	L<EV::DNS>, L<EV::AnyEvent>.	1216	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1217	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1218	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1219	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1220	event-loop agnostic and portable event driven programming.
462		1221
463	=head1 AUTHOR	1222	=head1 AUTHOR
464		1223
465	Marc Lehmann <schmorp@schmorp.de>	1224	Marc Lehmann <schmorp@schmorp.de>
466	http://home.schmorp.de/	1225	http://home.schmorp.de/
467		1226
468	=cut	1227	=cut
469		1228

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Comparing EV/EV.pm (file contents): Revision 1.22 by root, Fri Nov 2 11:02:22 2007 UTC vs. Revision 1.142 by root, Sat Mar 8 15:51:23 2014 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.22 by root, Fri Nov 2 11:02:22 2007 UTC vs.
Revision 1.142 by root, Sat Mar 8 15:51:23 2014 UTC