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

Comparing EV/EV.pm (file contents):
Revision 1.28 by root, Sun Nov 4 16:52:52 2007 UTC vs.
Revision 1.165 by root, Wed Mar 18 13:21:14 2020 UTC

…		…
2		2
3	EV - perl interface to libev, a high performance full-featured event loop	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
		8
		9	# TIMERS
		10
		11	my $w = EV::timer 2, 0, sub {
		12	warn "is called after 2s";
		13	};
		14
		15	my $w = EV::timer 2, 2, sub {
		16	warn "is called roughly every 2s (repeat = 2)";
		17	};
		18
		19	undef $w; # destroy event watcher again
		20
		21	my $w = EV::periodic 0, 60, 0, sub {
		22	warn "is called every minute, on the minute, exactly";
		23	};
		24
		25	# IO
		26
		27	my $w = EV::io *STDIN, EV::READ, sub {
		28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
		29	warn "stdin is readable, you entered: ", <STDIN>;
		30	};
		31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
8		39
9	# TIMERS	40	my $w = EV::child 666, 0, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
10		44
11	my $w = EV::timer 2, 0, sub {	45	# STAT CHANGES
12	warn "is called after 2s";	46	my $w = EV::stat "/etc/passwd", 10, sub {
13	};
14
15	my $w = EV::timer 2, 1, sub {
16	warn "is called roughly every 2s (repeat = 1)";
17	};
18
19	undef $w; # destroy event watcher again
20
21	my $w = EV::periodic 0, 60, sub {
22	warn "is called every minute, on the minute, exactly";
23	};
24
25	# IO
26
27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
29	warn "stdin is readable, you entered: ", <STDIN>;
30	};
31
32	# SIGNALS
33
34	my $w = EV::signal 'QUIT', sub {
35	warn "sigquit received\n";
36	};
37
38	my $w = EV::signal 3, sub {
39	warn "sigquit received (this is GNU/Linux, right?)\n";
40	};
41
42	# CHILD/PID STATUS CHANGES
43
44	my $w = EV::child 666, sub {
45	my ($w, $revents) = @_;	47	my ($w, $revents) = @_;
46	# my $pid = $w->rpid;	48	warn $w->path, " has changed somehow.\n";
47	my $status = $w->rstatus;
48	};	49	};
49		50
50	# MAINLOOP	51	# MAINLOOP
51	EV::loop; # loop until EV::loop_done is called	52	EV::run; # loop until EV::break is called or all watchers stop
52	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled	53	EV::run EV::RUN_ONCE; # block until at least one event could be handled
53	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block	54	EV::run EV::RUN_NOWAIT; # try to handle same events, but do not block
		55
		56	=head1 BEFORE YOU START USING THIS MODULE
		57
		58	If you only need timer, I/O, signal, child and idle watchers and not the
		59	advanced functionality of this module, consider using L<AnyEvent> instead,
		60	specifically the simplified API described in L<AE>.
		61
		62	When used with EV as backend, the L<AE> API is as fast as the native L<EV>
		63	API, but your programs/modules will still run with many other event loops.
54		64
55	=head1 DESCRIPTION	65	=head1 DESCRIPTION
56		66
57	This module provides an interface to libev	67	This module provides an interface to libev
58	(L<http://software.schmorp.de/pkg/libev.html>).	68	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		69	below is comprehensive, one might also consult the documentation of
		70	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		71	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		72	discussion on the available backends, or how to force a specific backend
		73	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		74	detailed information.
		75
		76	This module is very fast and scalable. It is actually so fast that you
		77	can use it through the L<AnyEvent> module, stay portable to other event
		78	loops (if you don't rely on any watcher types not available through it)
		79	and still be faster than with any other event loop currently supported in
		80	Perl.
		81
		82	=head2 PORTING FROM EV 3.X to 4.X
		83
		84	EV version 4 introduces a number of incompatible changes summarised
		85	here. According to the depreciation strategy used by libev, there is a
		86	compatibility layer in place so programs should continue to run unchanged
		87	(the XS interface lacks this layer, so programs using that one need to be
		88	updated).
		89
		90	This compatibility layer will be switched off in some future release.
		91
		92	All changes relevant to Perl are renames of symbols, functions and
		93	methods:
		94
		95	EV::loop => EV::run
		96	EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
		97	EV::LOOP_ONESHOT => EV::RUN_ONCE
		98
		99	EV::unloop => EV::break
		100	EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
		101	EV::UNLOOP_ONE => EV::BREAK_ONE
		102	EV::UNLOOP_ALL => EV::BREAK_ALL
		103
		104	EV::TIMEOUT => EV::TIMER
		105
		106	EV::loop_count => EV::iteration
		107	EV::loop_depth => EV::depth
		108	EV::loop_verify => EV::verify
		109
		110	The loop object methods corresponding to the functions above have been
		111	similarly renamed.
		112
		113	=head2 MODULE EXPORTS
		114
		115	This module does not export any symbols.
59		116
60	=cut	117	=cut
61		118
62	package EV;	119	package EV;
63		120
64	use strict;	121	use common::sense;
65		122
66	BEGIN {	123	BEGIN {
67	our $VERSION = '0.5';	124	our $VERSION = '4.33';
68	use XSLoader;	125	use XSLoader;
		126	local $^W = 0; # avoid spurious warning
69	XSLoader::load "EV", $VERSION;	127	XSLoader::load "EV", $VERSION;
70	}	128	}
71		129
72	@EV::Io::ISA =	130	@EV::IO::ISA =
73	@EV::Timer::ISA =	131	@EV::Timer::ISA =
74	@EV::Periodic::ISA =	132	@EV::Periodic::ISA =
75	@EV::Signal::ISA =	133	@EV::Signal::ISA =
		134	@EV::Child::ISA =
		135	@EV::Stat::ISA =
76	@EV::Idle::ISA =	136	@EV::Idle::ISA =
77	@EV::Prepare::ISA =	137	@EV::Prepare::ISA =
78	@EV::Check::ISA =	138	@EV::Check::ISA =
79	@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
80		208
81	=head1 BASIC INTERFACE	209	=head1 BASIC INTERFACE
82		210
83	=over 4	211	=over 4
84		212
85	=item $EV::DIED	213	=item $EV::DIED
86		214
87	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
88	throws an exception (with $@ containing thr error). The default prints an	216	throws an exception (with $@ containing the error). The default prints an
89	informative message and continues.	217	informative message and continues.
90		218
91	If this callback throws an exception it will be silently ignored.	219	If this callback throws an exception it will be silently ignored.
92		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
93	=item $time = EV::time	235	=item $time = EV::time
94		236
95	Returns the current time in (fractional) seconds since the epoch.	237	Returns the current time in (fractional) seconds since the epoch.
96		238
97	=item $time = EV::now	239	=item $time = EV::now
98		240
		241	=item $time = $loop->now
		242
99	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
100	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
101	usually faster then calling EV::time.	245	usually faster then calling EV::time.
102		246
103	=item $method = EV::ev_method	247	=item EV::now_update
104		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::run>.
		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 = $loop->backend
		292
105	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	293	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
106	or EV::METHOD_EPOLL).	294	or EV::BACKEND_EPOLL).
107		295
108	=item EV::loop [$flags]	296	=item $active = EV::run [$flags]
		297
		298	=item $active = $loop->run ([$flags])
109		299
110	Begin checking for events and calling callbacks. It returns when a	300	Begin checking for events and calling callbacks. It returns when a
111	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".
112		306
113	The $flags argument can be one of the following:	307	The $flags argument can be one of the following:
114		308
115	0 as above	309	0 as above
116	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	310	EV::RUN_ONCE block at most once (wait, but do not loop)
117	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	311	EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
118		312
119	=item EV::loop_done [$how]	313	=item EV::break [$how]
120		314
		315	=item $loop->break ([$how])
		316
121	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
122	call to EV::loop return.	318	innermost call to EV::run return.
123		319
124	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::run will
125	fast as possible.	321	return as fast as possible.
126		322
127	=back	323	When called with an argument of EV::BREAK_CANCEL, any pending break will
		324	be cancelled.
128		325
129	=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 an C<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	for 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
130		406
131	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
132	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
133	would create an EV::io watcher for that:	409	would create an EV::io watcher for that:
134		410
135	my $watcher = EV::io *STDIN, EV::READ, sub {	411	my $watcher = EV::io *STDIN, EV::READ, sub {
136	my ($watcher, $revents) = @_;	412	my ($watcher, $revents) = @_;
137	warn "yeah, STDIN should not be readable without blocking!\n"	413	warn "yeah, STDIN should now be readable without blocking!\n"
138	};	414	};
139		415
140	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
141	active watchers will have their callbacks invoked. All callbacks will be	417	active watchers will have their callbacks invoked. All callbacks will be
142	called with at least two arguments: the watcher and a bitmask of received	418	called with at least two arguments: the watcher and a bitmask of received
143	events.	419	events.
144		420
145	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
146	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
147	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,
148	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
149	(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).
150	uses EV::TIMEOUT).
151		426
152	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
153	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
154	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.
155		430
…		…
159		434
160	Also, all methods changing some aspect of a watcher (->set, ->priority,	435	Also, all methods changing some aspect of a watcher (->set, ->priority,
161	->fh and so on) automatically stop and start it again if it is active,	436	->fh and so on) automatically stop and start it again if it is active,
162	which means pending events get lost.	437	which means pending events get lost.
163		438
164	=head2 WATCHER TYPES	439	=head2 COMMON WATCHER METHODS
165		440
166	Now lets move to the existing watcher types and asociated methods.	441	This section lists methods common to all watchers.
167
168	The following methods are available for all watchers. Then followes a
169	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
170	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
171	any type-specific methods (if any).
172		442
173	=over 4	443	=over 4
174		444
175	=item $w->start	445	=item $w->start
176		446
…		…
180		450
181	=item $w->stop	451	=item $w->stop
182		452
183	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
184	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),
185	regardless of wether the watcher was active or not.	455	regardless of whether the watcher was active or not.
186		456
187	=item $bool = $w->is_active	457	=item $bool = $w->is_active
188		458
189	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!");
190		472
191	=item $current_cb = $w->cb	473	=item $current_cb = $w->cb
192		474
193	=item $old_cb = $w->cb ($new_cb)	475	=item $old_cb = $w->cb ($new_cb)
194		476
…		…
203	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
204	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default	486	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
205	-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
206	normalised to the nearest valid priority.	488	normalised to the nearest valid priority.
207		489
208	The default priority of any newly-created weatcher is 0.	490	The default priority of any newly-created watcher is 0.
209		491
		492	Note that the priority semantics have not yet been fleshed out and are
		493	subject to almost certain change.
		494
210	=item $w->trigger ($revents)	495	=item $w->invoke ($revents)
211		496
212	Call the callback now with the given event mask.	497	Call the callback now with the given event mask.
213		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::run> 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::run> 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::run> (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::run> 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::run> 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
214		552
215	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	553	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
216		554
217	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	555	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
218		556
		557	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		558
		559	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		560
219	As long as the returned watcher object is alive, call the C<$callback>	561	As long as the returned watcher object is alive, call the C<$callback>
220	when the events specified in C<$eventmask>.	562	when at least one of events specified in C<$eventmask> occurs.
221		563
222	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:
223		565
224	EV::READ wait until read() wouldn't block anymore	566	EV::READ wait until read() wouldn't block anymore
225	EV::WRITE wait until write() wouldn't block anymore	567	EV::WRITE wait until write() wouldn't block anymore
…		…
241		583
242	=item $old_eventmask = $w->events ($new_eventmask)	584	=item $old_eventmask = $w->events ($new_eventmask)
243		585
244	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.
245		587
		588	=back
		589
		590
		591	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		592
		593	=over 4
246		594
247	=item $w = EV::timer $after, $repeat, $callback	595	=item $w = EV::timer $after, $repeat, $callback
248		596
249	=item $w = EV::timer_ns $after, $repeat, $callback	597	=item $w = EV::timer_ns $after, $repeat, $callback
250		598
251	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	599	=item $w = $loop->timer ($after, $repeat, $callback)
252	the timer will be restarted (with the $repeat value as $after) after the	600
253	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 $after) after the callback returns.
254		606
255	This means that the callback would be called roughly after C<$after>	607	This means that the callback would be called roughly after C<$after>
256	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	608	seconds, and then every C<$repeat> seconds. The timer does his best not
257	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
258	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.
259		612
260	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
261	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
262	clock, the timer will nevertheless run (roughly) the same time.	615	clock, the timer will nevertheless run (roughly) the same time.
263		616
264	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.
265		618
266	=item $w->set ($after, $repeat)	619	=item $w->set ($after, $repeat = 0)
267		620
268	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
269	any time.	622	any time.
270		623
271	=item $w->again	624	=item $w->again
272		625
		626	=item $w->again ($repeat)
		627
273	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.
274		631
275	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
276	C<$repeat> seconds after now.	633	C<$repeat> seconds after now.
277		634
278	If the timer is active and non-repeating, it will be stopped.
279
280	If the timer is in active and repeating, start it.	635	If the timer is inactive and repeating, start it using the repeat value.
281		636
282	Otherwise do nothing.	637	Otherwise do nothing.
283		638
284	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
285	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
286	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
287	on the timeout.	642	on the timeout.
288		643
		644	If called with a C<$repeat> argument, then it uses this a timer repeat
		645	value.
289		646
		647	=item $after = $w->remaining
		648
		649	Calculates and returns the remaining time till the timer will fire.
		650
		651	=item $repeat = $w->repeat
		652
		653	=item $old_repeat = $w->repeat ($new_repeat)
		654
		655	Returns the current value of the repeat attribute and optionally sets a
		656	new one. Setting the new one will not restart the watcher - if the watcher
		657	is active, the new repeat value is used whenever it expires next.
		658
		659	=back
		660
		661
		662	=head3 PERIODIC WATCHERS - to cron or not to cron?
		663
		664	=over 4
		665
290	=item $w = EV::periodic $at, $interval, $callback	666	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
291		667
292	=item $w = EV::periodic_ns $at, $interval, $callback	668	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
293		669
294	Similar to EV::timer, but the time is given as an absolute point in time	670	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
295	(C<$at>), plus an optional C<$interval>.
296		671
297	If the C<$interval> is zero, then the callback will be called at the time	672	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
298	C<$at> if that is in the future, or as soon as possible if it is in the
299	past. It will not automatically repeat.
300		673
301	If the C<$interval> is nonzero, then the watcher will always be scheduled	674	Similar to EV::timer, but is not based on relative timeouts but on
302	to time out at the next C<$at + N * $interval> time.	675	absolute times. Apart from creating "simple" timers that trigger "at" the
		676	specified time, it can also be used for non-drifting absolute timers and
		677	more complex, cron-like, setups that are not adversely affected by time
		678	jumps (i.e. when the system clock is changed by explicit date -s or other
		679	means such as ntpd). It is also the most complex watcher type in EV.
303		680
304	This can be used to schedule a callback to run at very regular intervals,	681	It has three distinct "modes":
305	as long as the processing time is less then the interval (otherwise	682
306	obviously events will be skipped).	683	=over 4
		684
		685	=item * absolute timer ($interval = $reschedule_cb = 0)
		686
		687	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		688	will not adjust when a time jump occurs, that is, if it is to be run
		689	at January 1st 2011 then it will run when the system time reaches or
		690	surpasses this time.
		691
		692	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		693
		694	In this mode the watcher will always be scheduled to time out at the
		695	next C<$at + N * $interval> time (for the lowest integer N) and then repeat,
		696	regardless of any time jumps. Note that, since C<N> can be negative, the
		697	first trigger can happen before C<$at>.
		698
		699	This can be used to create timers that do not drift with respect to system
		700	time:
		701
		702	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		703
		704	That doesn't mean there will always be 3600 seconds in between triggers,
		705	but only that the the callback will be called when the system time shows a
		706	full hour (UTC).
307		707
308	Another way to think about it (for the mathematically inclined) is that	708	Another way to think about it (for the mathematically inclined) is that
309	EV::periodic will try to run the callback at the next possible time where	709	EV::periodic will try to run the callback in this mode at the next
310	C<$time = $at (mod $interval)>, regardless of any time jumps.	710	possible time where C<$time = $at (mod $interval)>, regardless of any time
		711	jumps.
311		712
312	This periodic timer is based on "wallclock time", that is, if the clock	713	=item * manual reschedule mode ($reschedule_cb = coderef)
313	changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at	714
314	the specified time. This means it will never drift (it might jitter, but	715	In this mode $interval and $at are both being ignored. Instead, each
315	it will not drift).	716	time the periodic watcher gets scheduled, the reschedule callback
		717	($reschedule_cb) will be called with the watcher as first, and the current
		718	time as second argument.
		719
		720	I<This callback MUST NOT stop or destroy this or any other periodic
		721	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		722	you need to stop it, return 1e30 and stop it afterwards. You may create
		723	and start an C<EV::prepare> watcher for this task.
		724
		725	It must return the next time to trigger, based on the passed time value
		726	(that is, the lowest time value larger than or equal to to the second
		727	argument). It will usually be called just before the callback will be
		728	triggered, but might be called at other times, too.
		729
		730	This can be used to create very complex timers, such as a timer that
		731	triggers on each midnight, local time (actually one day after the last
		732	midnight, to keep the example simple):
		733
		734	my $daily = EV::periodic 0, 0, sub {
		735	my ($w, $now) = @_;
		736
		737	use Time::Local ();
		738	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		739	Time::Local::timelocal_nocheck 0, 0, 0, $d + 1, $m, $y
		740	}, sub {
		741	print "it's midnight or likely shortly after, now\n";
		742	};
		743
		744	=back
316		745
317	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	746	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
318		747
319	=item $w->set ($at, $interval)	748	=item $w->set ($at, $interval, $reschedule_cb)
320		749
321	Reconfigures the watcher, see the constructor above for details. Can be at	750	Reconfigures the watcher, see the constructor above for details. Can be called at
322	any time.	751	any time.
323		752
		753	=item $w->again
		754
		755	Simply stops and starts the watcher again.
		756
		757	=item $time = $w->at
		758
		759	Return the time that the watcher is expected to trigger next.
		760
		761	=item $offset = $w->offset
		762
		763	=item $old_offset = $w->offset ($new_offset)
		764
		765	Returns the current value of the offset attribute and optionally sets a
		766	new one. Setting the new one will not restart the watcher - if the watcher
		767	is active, the new offset value is used whenever it expires next.
		768
		769	=item $interval = $w->interval
		770
		771	=item $old_interval = $w->interval ($new_interval)
		772
		773	See above, for the interval attribute.
		774
		775	=item $reschedule_cb = $w->reschedule_cb
		776
		777	=item $old_reschedule_cb = $w->reschedule_cb ($new_reschedule_cb)
		778
		779	See above, for the reschedule callback.
		780
		781	=back
		782
		783
		784	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		785
		786	=over 4
324		787
325	=item $w = EV::signal $signal, $callback	788	=item $w = EV::signal $signal, $callback
326		789
327	=item $w = EV::signal_ns $signal, $callback	790	=item $w = EV::signal_ns $signal, $callback
328		791
		792	=item $w = $loop->signal ($signal, $callback)
		793
		794	=item $w = $loop->signal_ns ($signal, $callback)
		795
329	Call the callback when $signal is received (the signal can be specified	796	Call the callback when $signal is received (the signal can be specified by
330	by number or by name, just as with kill or %SIG).	797	number or by name, just as with C<kill> or C<%SIG>).
		798
		799	Only one event loop can grab a given signal - attempting to grab the same
		800	signal from two EV loops will crash the program immediately or cause data
		801	corruption.
331		802
332	EV will grab the signal for the process (the kernel only allows one	803	EV will grab the signal for the process (the kernel only allows one
333	component to receive a signal at a time) when you start a signal watcher,	804	component to receive a signal at a time) when you start a signal watcher,
334	and removes it again when you stop it. Perl does the same when you	805	and removes it again when you stop it. Perl does the same when you
335	add/remove callbacks to %SIG, so watch out.	806	add/remove callbacks to C<%SIG>, so watch out.
336		807
337	You can have as many signal watchers per signal as you want.	808	You can have as many signal watchers per signal as you want.
338		809
339	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	810	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
340		811
341	=item $w->set ($signal)	812	=item $w->set ($signal)
342		813
343	Reconfigures the watcher, see the constructor above for details. Can be at	814	Reconfigures the watcher, see the constructor above for details. Can be
344	any time.	815	called at any time.
345		816
346	=item $current_signum = $w->signal	817	=item $current_signum = $w->signal
347		818
348	=item $old_signum = $w->signal ($new_signal)	819	=item $old_signum = $w->signal ($new_signal)
349		820
350	Returns the previously set signal (always as a number not name) and	821	Returns the previously set signal (always as a number not name) and
351	optionally set a new one.	822	optionally set a new one.
352		823
		824	=back
353		825
		826
		827	=head3 CHILD WATCHERS - watch out for process status changes
		828
		829	=over 4
		830
354	=item $w = EV::child $pid, $callback	831	=item $w = EV::child $pid, $trace, $callback
355		832
356	=item $w = EV::child_ns $pid, $callback	833	=item $w = EV::child_ns $pid, $trace, $callback
		834
		835	=item $w = $loop->child ($pid, $trace, $callback)
		836
		837	=item $w = $loop->child_ns ($pid, $trace, $callback)
357		838
358	Call the callback when a status change for pid C<$pid> (or any pid	839	Call the callback when a status change for pid C<$pid> (or any pid
359	if C<$pid> is 0) has been received. More precisely: when the process	840	if C<$pid> is 0) has been received (a status change happens when the
		841	process terminates or is killed, or, when trace is true, additionally when
		842	it is stopped or continued). More precisely: when the process receives
360	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	843	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
361	changed/zombie children and call the callback.	844	changed/zombie children and call the callback.
362		845
363	You can access both status and pid by using the C<rstatus> and C<rpid>	846	It is valid (and fully supported) to install a child watcher after a child
364	methods on the watcher object.	847	has exited but before the event loop has started its next iteration (for
		848	example, first you C<fork>, then the new child process might exit, and
		849	only then do you install a child watcher in the parent for the new pid).
365		850
		851	You can access both exit (or tracing) status and pid by using the
		852	C<rstatus> and C<rpid> methods on the watcher object.
		853
366	You can have as many pid watchers per pid as you want.	854	You can have as many pid watchers per pid as you want, they will all be
		855	called.
367		856
368	The C<child_ns> variant doesn't start (activate) the newly created watcher.	857	The C<child_ns> variant doesn't start (activate) the newly created watcher.
369		858
370	=item $w->set ($pid)	859	=item $w->set ($pid, $trace)
371		860
372	Reconfigures the watcher, see the constructor above for details. Can be at	861	Reconfigures the watcher, see the constructor above for details. Can be called at
373	any time.	862	any time.
374		863
375	=item $current_pid = $w->pid	864	=item $current_pid = $w->pid
376
377	=item $old_pid = $w->pid ($new_pid)
378		865
379	Returns the previously set process id and optionally set a new one.	866	Returns the previously set process id and optionally set a new one.
380		867
381	=item $exit_status = $w->rstatus	868	=item $exit_status = $w->rstatus
382		869
…		…
386	=item $pid = $w->rpid	873	=item $pid = $w->rpid
387		874
388	Return the pid of the awaited child (useful when you have installed a	875	Return the pid of the awaited child (useful when you have installed a
389	watcher for all pids).	876	watcher for all pids).
390		877
		878	=back
		879
		880
		881	=head3 STAT WATCHERS - did the file attributes just change?
		882
		883	=over 4
		884
		885	=item $w = EV::stat $path, $interval, $callback
		886
		887	=item $w = EV::stat_ns $path, $interval, $callback
		888
		889	=item $w = $loop->stat ($path, $interval, $callback)
		890
		891	=item $w = $loop->stat_ns ($path, $interval, $callback)
		892
		893	Call the callback when a file status change has been detected on
		894	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		895	to "path does not exist" is a status change like any other.
		896
		897	The C<$interval> is a recommended polling interval for systems where
		898	OS-supported change notifications don't exist or are not supported. If
		899	you use C<0> then an unspecified default is used (which is highly
		900	recommended!), which is to be expected to be around five seconds usually.
		901
		902	This watcher type is not meant for massive numbers of stat watchers,
		903	as even with OS-supported change notifications, this can be
		904	resource-intensive.
		905
		906	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		907
		908	=item ... = $w->stat
		909
		910	This call is very similar to the perl C<stat> built-in: It stats (using
		911	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		912	well as EV's idea of the current stat values) to the values found.
		913
		914	In scalar context, a boolean is return indicating success or failure of
		915	the stat. In list context, the same 13-value list as with stat is returned
		916	(except that the blksize and blocks fields are not reliable).
		917
		918	In the case of an error, errno is set to C<ENOENT> (regardless of the
		919	actual error value) and the C<nlink> value is forced to zero (if the stat
		920	was successful then nlink is guaranteed to be non-zero).
		921
		922	See also the next two entries for more info.
		923
		924	=item ... = $w->attr
		925
		926	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		927	the values most recently detected by EV. See the next entry for more info.
		928
		929	=item ... = $w->prev
		930
		931	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		932	the previous set of values, before the change.
		933
		934	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		935	to the values found I<before> a change was detected, while C<< $w->attr >>
		936	returns the values found leading to the change detection. The difference (if any)
		937	between C<prev> and C<attr> is what triggered the callback.
		938
		939	If you did something to the filesystem object and do not want to trigger
		940	yet another change, you can call C<stat> to update EV's idea of what the
		941	current attributes are.
		942
		943	=item $w->set ($path, $interval)
		944
		945	Reconfigures the watcher, see the constructor above for details. Can be
		946	called at any time.
		947
		948	=item $current_path = $w->path
		949
		950	=item $old_path = $w->path ($new_path)
		951
		952	Returns the previously set path and optionally set a new one.
		953
		954	=item $current_interval = $w->interval
		955
		956	=item $old_interval = $w->interval ($new_interval)
		957
		958	Returns the previously set interval and optionally set a new one. Can be
		959	used to query the actual interval used.
		960
		961	=back
		962
		963
		964	=head3 IDLE WATCHERS - when you've got nothing better to do...
		965
		966	=over 4
391		967
392	=item $w = EV::idle $callback	968	=item $w = EV::idle $callback
393		969
394	=item $w = EV::idle_ns $callback	970	=item $w = EV::idle_ns $callback
395		971
396	Call the callback when there are no pending io, timer/periodic, signal or	972	=item $w = $loop->idle ($callback)
397	child events, i.e. when the process is idle.	973
		974	=item $w = $loop->idle_ns ($callback)
		975
		976	Call the callback when there are no other pending watchers of the same or
		977	higher priority (excluding check, prepare and other idle watchers of the
		978	same or lower priority, of course). They are called idle watchers because
		979	when the watcher is the highest priority pending event in the process, the
		980	process is considered to be idle at that priority.
		981
		982	If you want a watcher that is only ever called when I<no> other events are
		983	outstanding you have to set the priority to C<EV::MINPRI>.
398		984
399	The process will not block as long as any idle watchers are active, and	985	The process will not block as long as any idle watchers are active, and
400	they will be called repeatedly until stopped.	986	they will be called repeatedly until stopped.
401		987
		988	For example, if you have idle watchers at priority C<0> and C<1>, and
		989	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		990	and the I/O watcher will always run when ready. Only when the idle watcher
		991	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		992	pending with the C<0>-priority idle watcher be invoked.
		993
402	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	994	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
403		995
		996	=back
		997
		998
		999	=head3 PREPARE WATCHERS - customise your event loop!
		1000
		1001	=over 4
404		1002
405	=item $w = EV::prepare $callback	1003	=item $w = EV::prepare $callback
406		1004
407	=item $w = EV::prepare_ns $callback	1005	=item $w = EV::prepare_ns $callback
		1006
		1007	=item $w = $loop->prepare ($callback)
		1008
		1009	=item $w = $loop->prepare_ns ($callback)
408		1010
409	Call the callback just before the process would block. You can still	1011	Call the callback just before the process would block. You can still
410	create/modify any watchers at this point.	1012	create/modify any watchers at this point.
411		1013
412	See the EV::check watcher, below, for explanations and an example.	1014	See the EV::check watcher, below, for explanations and an example.
413		1015
414	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	1016	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
415		1017
		1018	=back
		1019
		1020
		1021	=head3 CHECK WATCHERS - customise your event loop even more!
		1022
		1023	=over 4
416		1024
417	=item $w = EV::check $callback	1025	=item $w = EV::check $callback
418		1026
419	=item $w = EV::check_ns $callback	1027	=item $w = EV::check_ns $callback
		1028
		1029	=item $w = $loop->check ($callback)
		1030
		1031	=item $w = $loop->check_ns ($callback)
420		1032
421	Call the callback just after the process wakes up again (after it has	1033	Call the callback just after the process wakes up again (after it has
422	gathered events), but before any other callbacks have been invoked.	1034	gathered events), but before any other callbacks have been invoked.
423		1035
424	This is used to integrate other event-based software into the EV	1036	This can be used to integrate other event-based software into the EV
425	mainloop: You register a prepare callback and in there, you create io and	1037	mainloop: You register a prepare callback and in there, you create io and
426	timer watchers as required by the other software. Here is a real-world	1038	timer watchers as required by the other software. Here is a real-world
427	example of integrating Net::SNMP (with some details left out):	1039	example of integrating Net::SNMP (with some details left out):
428		1040
429	our @snmp_watcher;	1041	our @snmp_watcher;
…		…
432	# do nothing unless active	1044	# do nothing unless active
433	$dispatcher->{_event_queue_h}	1045	$dispatcher->{_event_queue_h}
434	or return;	1046	or return;
435		1047
436	# make the dispatcher handle any outstanding stuff	1048	# make the dispatcher handle any outstanding stuff
		1049	... not shown
437		1050
438	# create an IO watcher for each and every socket	1051	# create an I/O watcher for each and every socket
439	@snmp_watcher = (	1052	@snmp_watcher = (
440	(map { EV::io $_, EV::READ, sub { } }	1053	(map { EV::io $_, EV::READ, sub { } }
441	keys %{ $dispatcher->{_descriptors} }),	1054	keys %{ $dispatcher->{_descriptors} }),
		1055
		1056	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1057	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1058	0, sub { },
442	);	1059	);
443
444	# if there are any timeouts, also create a timer
445	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
446	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
447	};	1060	};
448		1061
449	The callbacks are irrelevant, the only purpose of those watchers is	1062	The callbacks are irrelevant (and are not even being called), the
450	to wake up the process as soon as one of those events occurs (socket	1063	only purpose of those watchers is to wake up the process as soon as
451	readable, or timer timed out). The corresponding EV::check watcher will then	1064	one of those events occurs (socket readable, or timer timed out). The
452	clean up:	1065	corresponding EV::check watcher will then clean up:
453		1066
454	our $snmp_check = EV::check sub {	1067	our $snmp_check = EV::check sub {
455	# destroy all watchers	1068	# destroy all watchers
456	@snmp_watcher = ();	1069	@snmp_watcher = ();
457		1070
458	# make the dispatcher handle any new stuff	1071	# make the dispatcher handle any new stuff
		1072	... not shown
459	};	1073	};
460		1074
461	The callbacks of the created watchers will not be called as the watchers	1075	The callbacks of the created watchers will not be called as the watchers
462	are destroyed before this cna happen (remember EV::check gets called	1076	are destroyed before this can happen (remember EV::check gets called
463	first).	1077	first).
464		1078
465	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1079	The C<check_ns> variant doesn't start (activate) the newly created watcher.
466		1080
467	=back	1081	=item EV::CHECK constant issues
468		1082
		1083	Like all other watcher types, there is a bitmask constant for use in
		1084	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1085	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1086	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1087	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1088	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1089	safe side.
		1090
		1091	=back
		1092
		1093
		1094	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1095
		1096	Fork watchers are called when a C<fork ()> was detected. The invocation
		1097	is done before the event loop blocks next and before C<check> watchers
		1098	are being called, and only in the child after the fork.
		1099
		1100	=over 4
		1101
		1102	=item $w = EV::fork $callback
		1103
		1104	=item $w = EV::fork_ns $callback
		1105
		1106	=item $w = $loop->fork ($callback)
		1107
		1108	=item $w = $loop->fork_ns ($callback)
		1109
		1110	Call the callback before the event loop is resumed in the child process
		1111	after a fork.
		1112
		1113	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1114
		1115	=back
		1116
		1117
		1118	=head3 EMBED WATCHERS - when one backend isn't enough...
		1119
		1120	This is a rather advanced watcher type that lets you embed one event loop
		1121	into another (currently only IO events are supported in the embedded
		1122	loop, other types of watchers might be handled in a delayed or incorrect
		1123	fashion and must not be used).
		1124
		1125	See the libev documentation at
		1126	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1127	(locally installed as F<EV::libev>) for more details.
		1128
		1129	In short, this watcher is most useful on BSD systems without working
		1130	kqueue to still be able to handle a large number of sockets:
		1131
		1132	my $socket_loop;
		1133
		1134	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1135	if (
		1136	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1137	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1138	) {
		1139	# use kqueue for sockets
		1140	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1141	}
		1142
		1143	# use the default loop otherwise
		1144	$socket_loop \|\|= EV::default_loop;
		1145
		1146	=over 4
		1147
		1148	=item $w = EV::embed $otherloop[, $callback]
		1149
		1150	=item $w = EV::embed_ns $otherloop[, $callback]
		1151
		1152	=item $w = $loop->embed ($otherloop[, $callback])
		1153
		1154	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1155
		1156	Call the callback when the embedded event loop (C<$otherloop>) has any
		1157	I/O activity. The C<$callback> is optional: if it is missing, then the
		1158	embedded event loop will be managed automatically (which is recommended),
		1159	otherwise you have to invoke C<sweep> yourself.
		1160
		1161	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1162
		1163	=back
		1164
		1165	=head3 ASYNC WATCHERS - how to wake up another event loop
		1166
		1167	Async watchers are provided by EV, but have little use in perl directly,
		1168	as perl neither supports threads running in parallel nor direct access to
		1169	signal handlers or other contexts where they could be of value.
		1170
		1171	It is, however, possible to use them from the XS level.
		1172
		1173	Please see the libev documentation for further details.
		1174
		1175	=over 4
		1176
		1177	=item $w = EV::async $callback
		1178
		1179	=item $w = EV::async_ns $callback
		1180
		1181	=item $w = $loop->async ($callback)
		1182
		1183	=item $w = $loop->async_ns ($callback)
		1184
		1185	=item $w->send
		1186
		1187	=item $bool = $w->async_pending
		1188
		1189	=back
		1190
		1191	=head3 CLEANUP WATCHERS - how to clean up when the event loop goes away
		1192
		1193	Cleanup watchers are not supported on the Perl level, they can only be
		1194	used via XS currently.
		1195
		1196
		1197	=head1 PERL SIGNALS
		1198
		1199	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1200	with EV is as the same as any other C library: Perl-signals will only be
		1201	handled when Perl runs, which means your signal handler might be invoked
		1202	only the next time an event callback is invoked.
		1203
		1204	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1205	ensure proper operations with regards to other event watchers.
		1206
		1207	If you cannot do this for whatever reason, you can also force a watcher
		1208	to be called on every event loop iteration by installing a C<EV::check>
		1209	watcher:
		1210
		1211	my $async_check = EV::check sub { };
		1212
		1213	This ensures that perl gets into control for a short time to handle any
		1214	pending signals, and also ensures (slightly) slower overall operation.
		1215
469	=head1 THREADS	1216	=head1 ITHREADS
470		1217
471	Threads are not supported by this in any way. Perl pseudo-threads is evil	1218	Ithreads are not supported by this module in any way. Perl pseudo-threads
472	stuff and must die.	1219	is evil stuff and must die. Real threads as provided by Coro are fully
		1220	supported (and enhanced support is available via L<Coro::EV>).
		1221
		1222	=head1 FORK
		1223
		1224	Most of the "improved" event delivering mechanisms of modern operating
		1225	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1226	not supported and usually destructive). Libev makes it possible to work
		1227	around this by having a function that recreates the kernel state after
		1228	fork in the child.
		1229
		1230	On non-win32 platforms, this module requires the pthread_atfork
		1231	functionality to do this automatically for you. This function is quite
		1232	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1233	negligible, because everything the function currently does is set a flag
		1234	that is checked only when the event loop gets used the next time, so when
		1235	you do fork but not use EV, the overhead is minimal.
		1236
		1237	On win32, there is no notion of fork so all this doesn't apply, of course.
473		1238
474	=cut	1239	=cut
475		1240
476	our $DIED = sub {	1241	our $DIED = sub {
477	warn "EV: error in callback (ignoring): $@";	1242	warn "EV: error in callback (ignoring): $@";
478	};	1243	};
479		1244
480	default_loop	1245	default_loop
481	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';	1246	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
482
483	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
484		1247
485	1;	1248	1;
486		1249
487	=head1 SEE ALSO	1250	=head1 SEE ALSO
488		1251
489	L<EV::DNS>, L<EV::AnyEvent>.	1252	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1253	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1254	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1255	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1256	event-loop agnostic and portable event driven programming.
490		1257
491	=head1 AUTHOR	1258	=head1 AUTHOR
492		1259
493	Marc Lehmann <schmorp@schmorp.de>	1260	Marc Lehmann <schmorp@schmorp.de>
494	http://home.schmorp.de/	1261	http://home.schmorp.de/
495		1262
496	=cut	1263	=cut
497		1264

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing EV/EV.pm (file contents): Revision 1.28 by root, Sun Nov 4 16:52:52 2007 UTC vs. Revision 1.165 by root, Wed Mar 18 13:21:14 2020 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.28 by root, Sun Nov 4 16:52:52 2007 UTC vs.
Revision 1.165 by root, Wed Mar 18 13:21:14 2020 UTC