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

Comparing EV/EV.pm (file contents):
Revision 1.26 by root, Fri Nov 2 23:22:17 2007 UTC vs.
Revision 1.151 by root, Tue Sep 4 23:14:45 2018 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::break 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 = '0.5';	124	our $VERSION = 4.22;
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::break or the flags 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 return value 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
…		…
157		434
158	Also, all methods changing some aspect of a watcher (->set, ->priority,	435	Also, all methods changing some aspect of a watcher (->set, ->priority,
159	->fh and so on) automatically stop and start it again if it is active,	436	->fh and so on) automatically stop and start it again if it is active,
160	which means pending events get lost.	437	which means pending events get lost.
161		438
162	=head2 WATCHER TYPES	439	=head2 COMMON WATCHER METHODS
163		440
164	Now lets move to the existing watcher types and asociated methods.	441	This section lists methods common to all watchers.
165
166	The following methods are available for all watchers. Then followes a
167	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
168	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
169	any type-specific methods (if any).
170		442
171	=over 4	443	=over 4
172		444
173	=item $w->start	445	=item $w->start
174		446
…		…
178		450
179	=item $w->stop	451	=item $w->stop
180		452
181	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
182	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),
183	regardless of wether the watcher was active or not.	455	regardless of whether the watcher was active or not.
184		456
185	=item $bool = $w->is_active	457	=item $bool = $w->is_active
186		458
187	Returns true if the watcher is active, false otherwise.	459	Returns true if the watcher is active, false otherwise.
		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!");
188		472
189	=item $current_cb = $w->cb	473	=item $current_cb = $w->cb
190		474
191	=item $old_cb = $w->cb ($new_cb)	475	=item $old_cb = $w->cb ($new_cb)
192		476
…		…
201	watchers with higher priority will be invoked first. The valid range of	485	watchers with higher priority will be invoked first. The valid range of
202	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default	486	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
203	-2). If the priority is outside this range it will automatically be	487	-2). If the priority is outside this range it will automatically be
204	normalised to the nearest valid priority.	488	normalised to the nearest valid priority.
205		489
206	The default priority of any newly-created weatcher is 0.	490	The default priority of any newly-created watcher is 0.
207		491
		492	Note that the priority semantics have not yet been fleshed out and are
		493	subject to almost certain change.
		494
208	=item $w->trigger ($revents)	495	=item $w->invoke ($revents)
209		496
210	Call the callback now with the given event mask.	497	Call the callback now with the given event mask.
211		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
212		552
213	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	553	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
214		554
215	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	555	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
216		556
		557	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		558
		559	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		560
217	As long as the returned watcher object is alive, call the C<$callback>	561	As long as the returned watcher object is alive, call the C<$callback>
218	when the events specified in C<$eventmask>.	562	when at least one of events specified in C<$eventmask> occurs.
219		563
220	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:
221		565
222	EV::READ wait until read() wouldn't block anymore	566	EV::READ wait until read() wouldn't block anymore
223	EV::WRITE wait until write() wouldn't block anymore	567	EV::WRITE wait until write() wouldn't block anymore
…		…
239		583
240	=item $old_eventmask = $w->events ($new_eventmask)	584	=item $old_eventmask = $w->events ($new_eventmask)
241		585
242	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.
243		587
		588	=back
		589
		590
		591	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		592
		593	=over 4
244		594
245	=item $w = EV::timer $after, $repeat, $callback	595	=item $w = EV::timer $after, $repeat, $callback
246		596
247	=item $w = EV::timer_ns $after, $repeat, $callback	597	=item $w = EV::timer_ns $after, $repeat, $callback
248		598
249	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	599	=item $w = $loop->timer ($after, $repeat, $callback)
250	the timer will be restarted (with the $repeat value as $after) after the	600
251	callback returns.	601	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		602
		603	Calls the callback after C<$after> seconds (which may be fractional or
		604	negative). If C<$repeat> is non-zero, the timer will be restarted (with
		605	the $repeat value as $after) after the callback returns.
252		606
253	This means that the callback would be called roughly after C<$after>	607	This means that the callback would be called roughly after C<$after>
254	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	608	seconds, and then every C<$repeat> seconds. The timer does his best not
255	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
256	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.
257		612
258	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
259	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
260	clock, the timer will nevertheless run (roughly) the same time.	615	clock, the timer will nevertheless run (roughly) the same time.
261		616
262	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.
263		618
264	=item $w->set ($after, $repeat)	619	=item $w->set ($after, $repeat = 0)
265		620
266	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
267	any time.	622	any time.
268		623
269	=item $w->again	624	=item $w->again
270		625
		626	=item $w->again ($repeat)
		627
271	Similar to the C<start> method, but has special semantics for repeating timers:	628	Similar to the C<start> method, but has special semantics for repeating timers:
		629
		630	If the timer is active and non-repeating, it will be stopped.
272		631
273	If the timer is active and repeating, reset the timeout to occur	632	If the timer is active and repeating, reset the timeout to occur
274	C<$repeat> seconds after now.	633	C<$repeat> seconds after now.
275		634
276	If the timer is active and non-repeating, it will be stopped.
277
278	If the timer is in active and repeating, start it.	635	If the timer is inactive and repeating, start it using the repeat value.
279		636
280	Otherwise do nothing.	637	Otherwise do nothing.
281		638
282	This behaviour is useful when you have a timeout for some IO	639	This behaviour is useful when you have a timeout for some IO
283	operation. You create a timer object with the same value for C<$after> and	640	operation. You create a timer object with the same value for C<$after> and
284	C<$repeat>, and then, in the read/write watcher, run the C<again> method	641	C<$repeat>, and then, in the read/write watcher, run the C<again> method
285	on the timeout.	642	on the timeout.
286		643
		644	If called with a C<$repeat> argument, then it uses this a timer repeat
		645	value.
287		646
		647	=item $after = $w->remaining
		648
		649	Calculates and returns the remaining time till the timer will fire.
		650
		651	=back
		652
		653
		654	=head3 PERIODIC WATCHERS - to cron or not to cron?
		655
		656	=over 4
		657
288	=item $w = EV::periodic $at, $interval, $callback	658	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
289		659
290	=item $w = EV::periodic_ns $at, $interval, $callback	660	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
291		661
292	Similar to EV::timer, but the time is given as an absolute point in time	662	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
293	(C<$at>), plus an optional C<$interval>.
294		663
295	If the C<$interval> is zero, then the callback will be called at the time	664	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
296	C<$at> if that is in the future, or as soon as possible if it is in the
297	past. It will not automatically repeat.
298		665
299	If the C<$interval> is nonzero, then the watcher will always be scheduled	666	Similar to EV::timer, but is not based on relative timeouts but on
300	to time out at the next C<$at + N * $interval> time.	667	absolute times. Apart from creating "simple" timers that trigger "at" the
		668	specified time, it can also be used for non-drifting absolute timers and
		669	more complex, cron-like, setups that are not adversely affected by time
		670	jumps (i.e. when the system clock is changed by explicit date -s or other
		671	means such as ntpd). It is also the most complex watcher type in EV.
301		672
302	This can be used to schedule a callback to run at very regular intervals,	673	It has three distinct "modes":
303	as long as the processing time is less then the interval (otherwise	674
304	obviously events will be skipped).	675	=over 4
		676
		677	=item * absolute timer ($interval = $reschedule_cb = 0)
		678
		679	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		680	will not adjust when a time jump occurs, that is, if it is to be run
		681	at January 1st 2011 then it will run when the system time reaches or
		682	surpasses this time.
		683
		684	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		685
		686	In this mode the watcher will always be scheduled to time out at the
		687	next C<$at + N * $interval> time (for the lowest integer N) and then repeat,
		688	regardless of any time jumps. Note that, since C<N> can be negative, the
		689	first trigger can happen before C<$at>.
		690
		691	This can be used to create timers that do not drift with respect to system
		692	time:
		693
		694	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		695
		696	That doesn't mean there will always be 3600 seconds in between triggers,
		697	but only that the the callback will be called when the system time shows a
		698	full hour (UTC).
305		699
306	Another way to think about it (for the mathematically inclined) is that	700	Another way to think about it (for the mathematically inclined) is that
307	EV::periodic will try to run the callback at the next possible time where	701	EV::periodic will try to run the callback in this mode at the next
308	C<$time = $at (mod $interval)>, regardless of any time jumps.	702	possible time where C<$time = $at (mod $interval)>, regardless of any time
		703	jumps.
309		704
310	This periodic timer is based on "wallclock time", that is, if the clock	705	=item * manual reschedule mode ($reschedule_cb = coderef)
311	changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at	706
312	the specified time. This means it will never drift (it might jitter, but	707	In this mode $interval and $at are both being ignored. Instead, each
313	it will not drift).	708	time the periodic watcher gets scheduled, the reschedule callback
		709	($reschedule_cb) will be called with the watcher as first, and the current
		710	time as second argument.
		711
		712	I<This callback MUST NOT stop or destroy this or any other periodic
		713	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		714	you need to stop it, return 1e30 and stop it afterwards. You may create
		715	and start a C<EV::prepare> watcher for this task.
		716
		717	It must return the next time to trigger, based on the passed time value
		718	(that is, the lowest time value larger than or equal to to the second
		719	argument). It will usually be called just before the callback will be
		720	triggered, but might be called at other times, too.
		721
		722	This can be used to create very complex timers, such as a timer that
		723	triggers on each midnight, local time (actually 24 hours after the last
		724	midnight, to keep the example simple. If you know a way to do it correctly
		725	in about the same space (without requiring elaborate modules), drop me a
		726	note :):
		727
		728	my $daily = EV::periodic 0, 0, sub {
		729	my ($w, $now) = @_;
		730
		731	use Time::Local ();
		732	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		733	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		734	}, sub {
		735	print "it's midnight or likely shortly after, now\n";
		736	};
		737
		738	=back
314		739
315	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	740	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
316		741
317	=item $w->set ($at, $interval)	742	=item $w->set ($at, $interval, $reschedule_cb)
318		743
319	Reconfigures the watcher, see the constructor above for details. Can be at	744	Reconfigures the watcher, see the constructor above for details. Can be called at
320	any time.	745	any time.
321		746
		747	=item $w->again
		748
		749	Simply stops and starts the watcher again.
		750
		751	=item $time = $w->at
		752
		753	Return the time that the watcher is expected to trigger next.
		754
		755	=back
		756
		757
		758	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		759
		760	=over 4
322		761
323	=item $w = EV::signal $signal, $callback	762	=item $w = EV::signal $signal, $callback
324		763
325	=item $w = EV::signal_ns $signal, $callback	764	=item $w = EV::signal_ns $signal, $callback
326		765
		766	=item $w = $loop->signal ($signal, $callback)
		767
		768	=item $w = $loop->signal_ns ($signal, $callback)
		769
327	Call the callback when $signal is received (the signal can be specified	770	Call the callback when $signal is received (the signal can be specified by
328	by number or by name, just as with kill or %SIG).	771	number or by name, just as with C<kill> or C<%SIG>).
		772
		773	Only one event loop can grab a given signal - attempting to grab the same
		774	signal from two EV loops will crash the program immediately or cause data
		775	corruption.
329		776
330	EV will grab the signal for the process (the kernel only allows one	777	EV will grab the signal for the process (the kernel only allows one
331	component to receive a signal at a time) when you start a signal watcher,	778	component to receive a signal at a time) when you start a signal watcher,
332	and removes it again when you stop it. Perl does the same when you	779	and removes it again when you stop it. Perl does the same when you
333	add/remove callbacks to %SIG, so watch out.	780	add/remove callbacks to C<%SIG>, so watch out.
334		781
335	You can have as many signal watchers per signal as you want.	782	You can have as many signal watchers per signal as you want.
336		783
337	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	784	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
338		785
339	=item $w->set ($signal)	786	=item $w->set ($signal)
340		787
341	Reconfigures the watcher, see the constructor above for details. Can be at	788	Reconfigures the watcher, see the constructor above for details. Can be
342	any time.	789	called at any time.
343		790
344	=item $current_signum = $w->signal	791	=item $current_signum = $w->signal
345		792
346	=item $old_signum = $w->signal ($new_signal)	793	=item $old_signum = $w->signal ($new_signal)
347		794
348	Returns the previously set signal (always as a number not name) and	795	Returns the previously set signal (always as a number not name) and
349	optionally set a new one.	796	optionally set a new one.
350		797
		798	=back
351		799
		800
		801	=head3 CHILD WATCHERS - watch out for process status changes
		802
		803	=over 4
		804
352	=item $w = EV::child $pid, $callback	805	=item $w = EV::child $pid, $trace, $callback
353		806
354	=item $w = EV::child_ns $pid, $callback	807	=item $w = EV::child_ns $pid, $trace, $callback
		808
		809	=item $w = $loop->child ($pid, $trace, $callback)
		810
		811	=item $w = $loop->child_ns ($pid, $trace, $callback)
355		812
356	Call the callback when a status change for pid C<$pid> (or any pid	813	Call the callback when a status change for pid C<$pid> (or any pid
357	if C<$pid> is 0) has been received. More precisely: when the process	814	if C<$pid> is 0) has been received (a status change happens when the
		815	process terminates or is killed, or, when trace is true, additionally when
		816	it is stopped or continued). More precisely: when the process receives
358	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	817	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
359	changed/zombie children and call the callback.	818	changed/zombie children and call the callback.
360		819
361	Unlike all other callbacks, this callback will be called with an	820	It is valid (and fully supported) to install a child watcher after a child
362	additional third argument which is the exit status. See the C<waitpid>	821	has exited but before the event loop has started its next iteration (for
363	function for details.	822	example, first you C<fork>, then the new child process might exit, and
		823	only then do you install a child watcher in the parent for the new pid).
364		824
		825	You can access both exit (or tracing) status and pid by using the
		826	C<rstatus> and C<rpid> methods on the watcher object.
		827
365	You can have as many pid watchers per pid as you want.	828	You can have as many pid watchers per pid as you want, they will all be
		829	called.
366		830
367	The C<child_ns> variant doesn't start (activate) the newly created watcher.	831	The C<child_ns> variant doesn't start (activate) the newly created watcher.
368		832
369	=item $w->set ($pid)	833	=item $w->set ($pid, $trace)
370		834
371	Reconfigures the watcher, see the constructor above for details. Can be at	835	Reconfigures the watcher, see the constructor above for details. Can be called at
372	any time.	836	any time.
373		837
374	=item $current_pid = $w->pid	838	=item $current_pid = $w->pid
375		839
376	=item $old_pid = $w->pid ($new_pid)
377
378	Returns the previously set process id and optionally set a new one.	840	Returns the previously set process id and optionally set a new one.
379		841
		842	=item $exit_status = $w->rstatus
		843
		844	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		845	in perlfunc).
		846
		847	=item $pid = $w->rpid
		848
		849	Return the pid of the awaited child (useful when you have installed a
		850	watcher for all pids).
		851
		852	=back
		853
		854
		855	=head3 STAT WATCHERS - did the file attributes just change?
		856
		857	=over 4
		858
		859	=item $w = EV::stat $path, $interval, $callback
		860
		861	=item $w = EV::stat_ns $path, $interval, $callback
		862
		863	=item $w = $loop->stat ($path, $interval, $callback)
		864
		865	=item $w = $loop->stat_ns ($path, $interval, $callback)
		866
		867	Call the callback when a file status change has been detected on
		868	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		869	to "path does not exist" is a status change like any other.
		870
		871	The C<$interval> is a recommended polling interval for systems where
		872	OS-supported change notifications don't exist or are not supported. If
		873	you use C<0> then an unspecified default is used (which is highly
		874	recommended!), which is to be expected to be around five seconds usually.
		875
		876	This watcher type is not meant for massive numbers of stat watchers,
		877	as even with OS-supported change notifications, this can be
		878	resource-intensive.
		879
		880	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		881
		882	=item ... = $w->stat
		883
		884	This call is very similar to the perl C<stat> built-in: It stats (using
		885	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		886	well as EV's idea of the current stat values) to the values found.
		887
		888	In scalar context, a boolean is return indicating success or failure of
		889	the stat. In list context, the same 13-value list as with stat is returned
		890	(except that the blksize and blocks fields are not reliable).
		891
		892	In the case of an error, errno is set to C<ENOENT> (regardless of the
		893	actual error value) and the C<nlink> value is forced to zero (if the stat
		894	was successful then nlink is guaranteed to be non-zero).
		895
		896	See also the next two entries for more info.
		897
		898	=item ... = $w->attr
		899
		900	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		901	the values most recently detected by EV. See the next entry for more info.
		902
		903	=item ... = $w->prev
		904
		905	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		906	the previous set of values, before the change.
		907
		908	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		909	to the values found I<before> a change was detected, while C<< $w->attr >>
		910	returns the values found leading to the change detection. The difference (if any)
		911	between C<prev> and C<attr> is what triggered the callback.
		912
		913	If you did something to the filesystem object and do not want to trigger
		914	yet another change, you can call C<stat> to update EV's idea of what the
		915	current attributes are.
		916
		917	=item $w->set ($path, $interval)
		918
		919	Reconfigures the watcher, see the constructor above for details. Can be
		920	called at any time.
		921
		922	=item $current_path = $w->path
		923
		924	=item $old_path = $w->path ($new_path)
		925
		926	Returns the previously set path and optionally set a new one.
		927
		928	=item $current_interval = $w->interval
		929
		930	=item $old_interval = $w->interval ($new_interval)
		931
		932	Returns the previously set interval and optionally set a new one. Can be
		933	used to query the actual interval used.
		934
		935	=back
		936
		937
		938	=head3 IDLE WATCHERS - when you've got nothing better to do...
		939
		940	=over 4
380		941
381	=item $w = EV::idle $callback	942	=item $w = EV::idle $callback
382		943
383	=item $w = EV::idle_ns $callback	944	=item $w = EV::idle_ns $callback
384		945
385	Call the callback when there are no pending io, timer/periodic, signal or	946	=item $w = $loop->idle ($callback)
386	child events, i.e. when the process is idle.	947
		948	=item $w = $loop->idle_ns ($callback)
		949
		950	Call the callback when there are no other pending watchers of the same or
		951	higher priority (excluding check, prepare and other idle watchers of the
		952	same or lower priority, of course). They are called idle watchers because
		953	when the watcher is the highest priority pending event in the process, the
		954	process is considered to be idle at that priority.
		955
		956	If you want a watcher that is only ever called when I<no> other events are
		957	outstanding you have to set the priority to C<EV::MINPRI>.
387		958
388	The process will not block as long as any idle watchers are active, and	959	The process will not block as long as any idle watchers are active, and
389	they will be called repeatedly until stopped.	960	they will be called repeatedly until stopped.
390		961
		962	For example, if you have idle watchers at priority C<0> and C<1>, and
		963	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		964	and the I/O watcher will always run when ready. Only when the idle watcher
		965	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		966	pending with the C<0>-priority idle watcher be invoked.
		967
391	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	968	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
392		969
		970	=back
		971
		972
		973	=head3 PREPARE WATCHERS - customise your event loop!
		974
		975	=over 4
393		976
394	=item $w = EV::prepare $callback	977	=item $w = EV::prepare $callback
395		978
396	=item $w = EV::prepare_ns $callback	979	=item $w = EV::prepare_ns $callback
		980
		981	=item $w = $loop->prepare ($callback)
		982
		983	=item $w = $loop->prepare_ns ($callback)
397		984
398	Call the callback just before the process would block. You can still	985	Call the callback just before the process would block. You can still
399	create/modify any watchers at this point.	986	create/modify any watchers at this point.
400		987
401	See the EV::check watcher, below, for explanations and an example.	988	See the EV::check watcher, below, for explanations and an example.
402		989
403	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	990	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
404		991
		992	=back
		993
		994
		995	=head3 CHECK WATCHERS - customise your event loop even more!
		996
		997	=over 4
405		998
406	=item $w = EV::check $callback	999	=item $w = EV::check $callback
407		1000
408	=item $w = EV::check_ns $callback	1001	=item $w = EV::check_ns $callback
		1002
		1003	=item $w = $loop->check ($callback)
		1004
		1005	=item $w = $loop->check_ns ($callback)
409		1006
410	Call the callback just after the process wakes up again (after it has	1007	Call the callback just after the process wakes up again (after it has
411	gathered events), but before any other callbacks have been invoked.	1008	gathered events), but before any other callbacks have been invoked.
412		1009
413	This is used to integrate other event-based software into the EV	1010	This can be used to integrate other event-based software into the EV
414	mainloop: You register a prepare callback and in there, you create io and	1011	mainloop: You register a prepare callback and in there, you create io and
415	timer watchers as required by the other software. Here is a real-world	1012	timer watchers as required by the other software. Here is a real-world
416	example of integrating Net::SNMP (with some details left out):	1013	example of integrating Net::SNMP (with some details left out):
417		1014
418	our @snmp_watcher;	1015	our @snmp_watcher;
…		…
421	# do nothing unless active	1018	# do nothing unless active
422	$dispatcher->{_event_queue_h}	1019	$dispatcher->{_event_queue_h}
423	or return;	1020	or return;
424		1021
425	# make the dispatcher handle any outstanding stuff	1022	# make the dispatcher handle any outstanding stuff
		1023	... not shown
426		1024
427	# create an IO watcher for each and every socket	1025	# create an I/O watcher for each and every socket
428	@snmp_watcher = (	1026	@snmp_watcher = (
429	(map { EV::io $_, EV::READ, sub { } }	1027	(map { EV::io $_, EV::READ, sub { } }
430	keys %{ $dispatcher->{_descriptors} }),	1028	keys %{ $dispatcher->{_descriptors} }),
		1029
		1030	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1031	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1032	0, sub { },
431	);	1033	);
432
433	# if there are any timeouts, also create a timer
434	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
435	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
436	};	1034	};
437		1035
438	The callbacks are irrelevant, the only purpose of those watchers is	1036	The callbacks are irrelevant (and are not even being called), the
439	to wake up the process as soon as one of those events occurs (socket	1037	only purpose of those watchers is to wake up the process as soon as
440	readable, or timer timed out). The corresponding EV::check watcher will then	1038	one of those events occurs (socket readable, or timer timed out). The
441	clean up:	1039	corresponding EV::check watcher will then clean up:
442		1040
443	our $snmp_check = EV::check sub {	1041	our $snmp_check = EV::check sub {
444	# destroy all watchers	1042	# destroy all watchers
445	@snmp_watcher = ();	1043	@snmp_watcher = ();
446		1044
447	# make the dispatcher handle any new stuff	1045	# make the dispatcher handle any new stuff
		1046	... not shown
448	};	1047	};
449		1048
450	The callbacks of the created watchers will not be called as the watchers	1049	The callbacks of the created watchers will not be called as the watchers
451	are destroyed before this cna happen (remember EV::check gets called	1050	are destroyed before this can happen (remember EV::check gets called
452	first).	1051	first).
453		1052
454	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1053	The C<check_ns> variant doesn't start (activate) the newly created watcher.
455		1054
456	=back	1055	=item EV::CHECK constant issues
457		1056
		1057	Like all other watcher types, there is a bitmask constant for use in
		1058	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1059	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1060	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1061	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1062	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1063	safe side.
		1064
		1065	=back
		1066
		1067
		1068	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1069
		1070	Fork watchers are called when a C<fork ()> was detected. The invocation
		1071	is done before the event loop blocks next and before C<check> watchers
		1072	are being called, and only in the child after the fork.
		1073
		1074	=over 4
		1075
		1076	=item $w = EV::fork $callback
		1077
		1078	=item $w = EV::fork_ns $callback
		1079
		1080	=item $w = $loop->fork ($callback)
		1081
		1082	=item $w = $loop->fork_ns ($callback)
		1083
		1084	Call the callback before the event loop is resumed in the child process
		1085	after a fork.
		1086
		1087	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1088
		1089	=back
		1090
		1091
		1092	=head3 EMBED WATCHERS - when one backend isn't enough...
		1093
		1094	This is a rather advanced watcher type that lets you embed one event loop
		1095	into another (currently only IO events are supported in the embedded
		1096	loop, other types of watchers might be handled in a delayed or incorrect
		1097	fashion and must not be used).
		1098
		1099	See the libev documentation at
		1100	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1101	(locally installed as F<EV::libev>) for more details.
		1102
		1103	In short, this watcher is most useful on BSD systems without working
		1104	kqueue to still be able to handle a large number of sockets:
		1105
		1106	my $socket_loop;
		1107
		1108	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1109	if (
		1110	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1111	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1112	) {
		1113	# use kqueue for sockets
		1114	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1115	}
		1116
		1117	# use the default loop otherwise
		1118	$socket_loop \|\|= EV::default_loop;
		1119
		1120	=over 4
		1121
		1122	=item $w = EV::embed $otherloop[, $callback]
		1123
		1124	=item $w = EV::embed_ns $otherloop[, $callback]
		1125
		1126	=item $w = $loop->embed ($otherloop[, $callback])
		1127
		1128	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1129
		1130	Call the callback when the embedded event loop (C<$otherloop>) has any
		1131	I/O activity. The C<$callback> is optional: if it is missing, then the
		1132	embedded event loop will be managed automatically (which is recommended),
		1133	otherwise you have to invoke C<sweep> yourself.
		1134
		1135	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1136
		1137	=back
		1138
		1139	=head3 ASYNC WATCHERS - how to wake up another event loop
		1140
		1141	Async watchers are provided by EV, but have little use in perl directly,
		1142	as perl neither supports threads running in parallel nor direct access to
		1143	signal handlers or other contexts where they could be of value.
		1144
		1145	It is, however, possible to use them from the XS level.
		1146
		1147	Please see the libev documentation for further details.
		1148
		1149	=over 4
		1150
		1151	=item $w = EV::async $callback
		1152
		1153	=item $w = EV::async_ns $callback
		1154
		1155	=item $w = $loop->async ($callback)
		1156
		1157	=item $w = $loop->async_ns ($callback)
		1158
		1159	=item $w->send
		1160
		1161	=item $bool = $w->async_pending
		1162
		1163	=back
		1164
		1165	=head3 CLEANUP WATCHERS - how to clean up when the event loop goes away
		1166
		1167	Cleanup watchers are not supported on the Perl level, they can only be
		1168	used via XS currently.
		1169
		1170
		1171	=head1 PERL SIGNALS
		1172
		1173	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1174	with EV is as the same as any other C library: Perl-signals will only be
		1175	handled when Perl runs, which means your signal handler might be invoked
		1176	only the next time an event callback is invoked.
		1177
		1178	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1179	ensure proper operations with regards to other event watchers.
		1180
		1181	If you cannot do this for whatever reason, you can also force a watcher
		1182	to be called on every event loop iteration by installing a C<EV::check>
		1183	watcher:
		1184
		1185	my $async_check = EV::check sub { };
		1186
		1187	This ensures that perl gets into control for a short time to handle any
		1188	pending signals, and also ensures (slightly) slower overall operation.
		1189
458	=head1 THREADS	1190	=head1 ITHREADS
459		1191
460	Threads are not supported by this in any way. Perl pseudo-threads is evil	1192	Ithreads are not supported by this module in any way. Perl pseudo-threads
461	stuff and must die.	1193	is evil stuff and must die. Real threads as provided by Coro are fully
		1194	supported (and enhanced support is available via L<Coro::EV>).
		1195
		1196	=head1 FORK
		1197
		1198	Most of the "improved" event delivering mechanisms of modern operating
		1199	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1200	not supported and usually destructive). Libev makes it possible to work
		1201	around this by having a function that recreates the kernel state after
		1202	fork in the child.
		1203
		1204	On non-win32 platforms, this module requires the pthread_atfork
		1205	functionality to do this automatically for you. This function is quite
		1206	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1207	negligible, because everything the function currently does is set a flag
		1208	that is checked only when the event loop gets used the next time, so when
		1209	you do fork but not use EV, the overhead is minimal.
		1210
		1211	On win32, there is no notion of fork so all this doesn't apply, of course.
462		1212
463	=cut	1213	=cut
464		1214
465	our $DIED = sub {	1215	our $DIED = sub {
466	warn "EV: error in callback (ignoring): $@";	1216	warn "EV: error in callback (ignoring): $@";
467	};	1217	};
468		1218
469	init	1219	default_loop
470	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';	1220	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
471
472	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
473		1221
474	1;	1222	1;
475		1223
476	=head1 SEE ALSO	1224	=head1 SEE ALSO
477		1225
478	L<EV::DNS>, L<EV::AnyEvent>.	1226	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1227	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1228	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1229	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1230	event-loop agnostic and portable event driven programming.
479		1231
480	=head1 AUTHOR	1232	=head1 AUTHOR
481		1233
482	Marc Lehmann <schmorp@schmorp.de>	1234	Marc Lehmann <schmorp@schmorp.de>
483	http://home.schmorp.de/	1235	http://home.schmorp.de/
484		1236
485	=cut	1237	=cut
486		1238

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Comparing EV/EV.pm (file contents): Revision 1.26 by root, Fri Nov 2 23:22:17 2007 UTC vs. Revision 1.151 by root, Tue Sep 4 23:14:45 2018 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.26 by root, Fri Nov 2 23:22:17 2007 UTC vs.
Revision 1.151 by root, Tue Sep 4 23:14:45 2018 UTC