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

Comparing EV/EV.pm (file contents):
Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs.
Revision 1.131 by root, Sun Dec 5 11:45:22 2010 UTC

…		…
2		2
3	EV - perl interface to libev, a high performance full-featured event loop	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
		8
		9	# TIMERS
		10
		11	my $w = EV::timer 2, 0, sub {
		12	warn "is called after 2s";
		13	};
		14
		15	my $w = EV::timer 2, 2, sub {
		16	warn "is called roughly every 2s (repeat = 2)";
		17	};
		18
		19	undef $w; # destroy event watcher again
		20
		21	my $w = EV::periodic 0, 60, 0, sub {
		22	warn "is called every minute, on the minute, exactly";
		23	};
		24
		25	# IO
		26
		27	my $w = EV::io *STDIN, EV::READ, sub {
		28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
		29	warn "stdin is readable, you entered: ", <STDIN>;
		30	};
		31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
8		39
9	# TIMERS	40	my $w = EV::child 666, 0, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
10		44
11	my $w = EV::timer 2, 0, sub {	45	# STAT CHANGES
12	warn "is called after 2s";	46	my $w = EV::stat "/etc/passwd", 10, sub {
13	};
14
15	my $w = EV::timer 2, 1, sub {
16	warn "is called roughly every 2s (repeat = 1)";
17	};
18
19	undef $w; # destroy event watcher again
20
21	my $w = EV::periodic 0, 60, 0, sub {
22	warn "is called every minute, on the minute, exactly";
23	};
24
25	# IO
26
27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
29	warn "stdin is readable, you entered: ", <STDIN>;
30	};
31
32	# SIGNALS
33
34	my $w = EV::signal 'QUIT', sub {
35	warn "sigquit received\n";
36	};
37
38	my $w = EV::signal 3, sub {
39	warn "sigquit received (this is GNU/Linux, right?)\n";
40	};
41
42	# CHILD/PID STATUS CHANGES
43
44	my $w = EV::child 666, sub {
45	my ($w, $revents) = @_;	47	my ($w, $revents) = @_;
46	# my $pid = $w->rpid;	48	warn $w->path, " has changed somehow.\n";
47	my $status = $w->rstatus;
48	};	49	};
49		50
50	# MAINLOOP	51	# MAINLOOP
51	EV::loop; # loop until EV::loop_done is called	52	EV::loop; # loop until EV::unloop is called or all watchers stop
52	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled	53	EV::loop EV::LOOP_ONESHOT; # 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::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
		55
		56	=head1 BEFORE YOU START USING THIS MODULE
		57
		58	If you only need timer, I/O, signal, child and idle watchers and not the
		59	advanced functionality of this module, consider using L<AnyEvent> instead,
		60	specifically the simplified API described in L<AE>.
		61
		62	When used with EV as backend, the L<AE> API is as fast as the native L<EV>
		63	API, but your programs/modules will still run with many other event loops.
54		64
55	=head1 DESCRIPTION	65	=head1 DESCRIPTION
56		66
57	This module provides an interface to libev	67	This module provides an interface to libev
58	(L<http://software.schmorp.de/pkg/libev.html>).	68	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
		69	below is comprehensive, one might also consult the documentation of
		70	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		71	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		72	discussion on the available backends, or how to force a specific backend
		73	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		74	detailed information.
		75
		76	This module is very fast and scalable. It is actually so fast that you
		77	can use it through the L<AnyEvent> module, stay portable to other event
		78	loops (if you don't rely on any watcher types not available through it)
		79	and still be faster than with any other event loop currently supported in
		80	Perl.
		81
		82	=head2 PORTING FROM EV 3.X to 4.X
		83
		84	EV version 4 introduces a number of incompatible changes summarised
		85	here. According to the depreciation strategy used by libev, there is a
		86	compatibility layer in place so programs should continue to run unchanged
		87	(the XS interface lacks this layer, so programs using that one need to be
		88	updated).
		89
		90	This compatibility layer will be switched off in some future release.
		91
		92	All changes relevant to Perl are renames of symbols, functions and
		93	methods:
		94
		95	EV::loop => EV::run
		96	EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
		97	EV::LOOP_ONESHOT => EV::RUN_ONCE
		98
		99	EV::unloop => EV::break
		100	EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
		101	EV::UNLOOP_ONE => EV::BREAK_ONE
		102	EV::UNLOOP_ALL => EV::BREAK_ALL
		103
		104	EV::TIMEOUT => EV::TIMER
		105
		106	EV::loop_count => EV::iteration
		107	EV::loop_depth => EV::depth
		108	EV::loop_verify => EV::verify
		109
		110	The loop object methods corresponding to the functions above have been
		111	similarly renamed.
		112
		113	=head2 MODULE EXPORTS
		114
		115	This module does not export any symbols.
59		116
60	=cut	117	=cut
61		118
62	package EV;	119	package EV;
63		120
64	use strict;	121	use common::sense;
65		122
66	BEGIN {	123	BEGIN {
67	our $VERSION = '0.7';	124	our $VERSION = '4.01';
68	use XSLoader;	125	use XSLoader;
69	XSLoader::load "EV", $VERSION;	126	XSLoader::load "EV", $VERSION;
70	}	127	}
71		128
72	@EV::Io::ISA =	129	@EV::IO::ISA =
73	@EV::Timer::ISA =	130	@EV::Timer::ISA =
74	@EV::Periodic::ISA =	131	@EV::Periodic::ISA =
75	@EV::Signal::ISA =	132	@EV::Signal::ISA =
		133	@EV::Child::ISA =
		134	@EV::Stat::ISA =
76	@EV::Idle::ISA =	135	@EV::Idle::ISA =
77	@EV::Prepare::ISA =	136	@EV::Prepare::ISA =
78	@EV::Check::ISA =	137	@EV::Check::ISA =
79	@EV::Child::ISA = "EV::Watcher";	138	@EV::Embed::ISA =
		139	@EV::Fork::ISA =
		140	@EV::Async::ISA =
		141	"EV::Watcher";
		142
		143	@EV::Loop::Default::ISA = "EV::Loop";
		144
		145	=head1 EVENT LOOPS
		146
		147	EV supports multiple event loops: There is a single "default event loop"
		148	that can handle everything including signals and child watchers, and any
		149	number of "dynamic event loops" that can use different backends (with
		150	various limitations), but no child and signal watchers.
		151
		152	You do not have to do anything to create the default event loop: When
		153	the module is loaded a suitable backend is selected on the premise of
		154	selecting a working backend (which for example rules out kqueue on most
		155	BSDs). Modules should, unless they have "special needs" always use the
		156	default loop as this is fastest (perl-wise), best supported by other
		157	modules (e.g. AnyEvent or Coro) and most portable event loop.
		158
		159	For specific programs you can create additional event loops dynamically.
		160
		161	If you want to take advantage of kqueue (which often works properly for
		162	sockets only) even though the default loop doesn't enable it, you can
		163	I<embed> a kqueue loop into the default loop: running the default loop
		164	will then also service the kqueue loop to some extent. See the example in
		165	the section about embed watchers for an example on how to achieve that.
		166
		167	=over 4
		168
		169	=item $loop = new EV::Loop [$flags]
		170
		171	Create a new event loop as per the specified flags. Please refer to
		172	the C<ev_loop_new ()> function description in the libev documentation
		173	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		174	or locally-installed as F<EV::libev> manpage) for more info.
		175
		176	The loop will automatically be destroyed when it is no longer referenced
		177	by any watcher and the loop object goes out of scope.
		178
		179	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		180	is recommended, as only the default event loop is protected by this
		181	module. If you I<are> embedding this loop in the default loop, this is not
		182	necessary, as C<EV::embed> automatically does the right thing on fork.
		183
		184	=item $loop->loop_fork
		185
		186	Must be called after a fork in the child, before entering or continuing
		187	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		188	this function automatically, at some performance loss (refer to the libev
		189	documentation).
		190
		191	=item $loop->loop_verify
		192
		193	Calls C<ev_verify> to make internal consistency checks (for debugging
		194	libev) and abort the program if any data structures were found to be
		195	corrupted.
		196
		197	=item $loop = EV::default_loop [$flags]
		198
		199	Return the default loop (which is a singleton object). Since this module
		200	already creates the default loop with default flags, specifying flags here
		201	will not have any effect unless you destroy the default loop first, which
		202	isn't supported. So in short: don't do it, and if you break it, you get to
		203	keep the pieces.
		204
		205	=back
		206
80		207
81	=head1 BASIC INTERFACE	208	=head1 BASIC INTERFACE
82		209
83	=over 4	210	=over 4
84		211
85	=item $EV::DIED	212	=item $EV::DIED
86		213
87	Must contain a reference to a function that is called when a callback	214	Must contain a reference to a function that is called when a callback
88	throws an exception (with $@ containing thr error). The default prints an	215	throws an exception (with $@ containing the error). The default prints an
89	informative message and continues.	216	informative message and continues.
90		217
91	If this callback throws an exception it will be silently ignored.	218	If this callback throws an exception it will be silently ignored.
92		219
		220	=item $flags = EV::supported_backends
		221
		222	=item $flags = EV::recommended_backends
		223
		224	=item $flags = EV::embeddable_backends
		225
		226	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		227	instance of EV, the set of recommended backends (supposed to be good) for
		228	this platform and the set of embeddable backends (see EMBED WATCHERS).
		229
		230	=item EV::sleep $seconds
		231
		232	Block the process for the given number of (fractional) seconds.
		233
93	=item $time = EV::time	234	=item $time = EV::time
94		235
95	Returns the current time in (fractional) seconds since the epoch.	236	Returns the current time in (fractional) seconds since the epoch.
96		237
97	=item $time = EV::now	238	=item $time = EV::now
98		239
		240	=item $time = $loop->now
		241
99	Returns the time the last event loop iteration has been started. This	242	Returns the time the last event loop iteration has been started. This
100	is the time that (relative) timers are based on, and refering to it is	243	is the time that (relative) timers are based on, and referring to it is
101	usually faster then calling EV::time.	244	usually faster then calling EV::time.
102		245
103	=item $method = EV::ev_method	246	=item EV::now_update
104		247
		248	=item $loop->now_update
		249
		250	Establishes the current time by querying the kernel, updating the time
		251	returned by C<EV::now> in the progress. This is a costly operation and
		252	is usually done automatically within C<EV::loop>.
		253
		254	This function is rarely useful, but when some event callback runs for a
		255	very long time without entering the event loop, updating libev's idea of
		256	the current time is a good idea.
		257
		258	=item EV::suspend
		259
		260	=item $loop->suspend
		261
		262	=item EV::resume
		263
		264	=item $loop->resume
		265
		266	These two functions suspend and resume a loop, for use when the loop is
		267	not used for a while and timeouts should not be processed.
		268
		269	A typical use case would be an interactive program such as a game: When
		270	the user presses C<^Z> to suspend the game and resumes it an hour later it
		271	would be best to handle timeouts as if no time had actually passed while
		272	the program was suspended. This can be achieved by calling C<suspend>
		273	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		274	C<resume> directly afterwards to resume timer processing.
		275
		276	Effectively, all C<timer> watchers will be delayed by the time spend
		277	between C<suspend> and C<resume>, and all C<periodic> watchers
		278	will be rescheduled (that is, they will lose any events that would have
		279	occured while suspended).
		280
		281	After calling C<suspend> you B<must not> call I<any> function on the given
		282	loop other than C<resume>, and you B<must not> call C<resume>
		283	without a previous call to C<suspend>.
		284
		285	Calling C<suspend>/C<resume> has the side effect of updating the event
		286	loop time (see C<now_update>).
		287
		288	=item $backend = EV::backend
		289
		290	=item $backend = $loop->backend
		291
105	Returns an integer describing the backend used by libev (EV::METHOD_SELECT	292	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
106	or EV::METHOD_EPOLL).	293	or EV::BACKEND_EPOLL).
107		294
108	=item EV::loop [$flags]	295	=item EV::loop [$flags]
109		296
		297	=item $loop->loop ([$flags])
		298
110	Begin checking for events and calling callbacks. It returns when a	299	Begin checking for events and calling callbacks. It returns when a
111	callback calls EV::loop_done.	300	callback calls EV::unloop.
112		301
113	The $flags argument can be one of the following:	302	The $flags argument can be one of the following:
114		303
115	0 as above	304	0 as above
116	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	305	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	306	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118		307
119	=item EV::loop_done [$how]	308	=item EV::unloop [$how]
120		309
		310	=item $loop->unloop ([$how])
		311
121	When called with no arguments or an argument of 1, makes the innermost	312	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122	call to EV::loop return.	313	innermost call to EV::loop return.
123		314
124	When called with an agrument of 2, all calls to EV::loop will return as	315	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125	fast as possible.	316	fast as possible.
126		317
127	=back	318	=item $count = EV::loop_count
128		319
129	=head2 WATCHER	320	=item $count = $loop->loop_count
		321
		322	Return the number of times the event loop has polled for new
		323	events. Sometimes useful as a generation counter.
		324
		325	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		326
		327	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		328
		329	This function rolls together an I/O and a timer watcher for a single
		330	one-shot event without the need for managing a watcher object.
		331
		332	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		333	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		334	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		335	you do not want to wait for some I/O event, specify C<undef> for
		336	C<$fh_or_undef> and C<0> for C<$events>).
		337
		338	If timeout is C<undef> or negative, then there will be no
		339	timeout. Otherwise a EV::timer with this value will be started.
		340
		341	When an error occurs or either the timeout or I/O watcher triggers, then
		342	the callback will be called with the received event set (in general
		343	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		344	C<EV::WRITE> and C<EV::TIMER>).
		345
		346	EV::once doesn't return anything: the watchers stay active till either
		347	of them triggers, then they will be stopped and freed, and the callback
		348	invoked.
		349
		350	=item EV::feed_fd_event ($fd, $revents)
		351
		352	=item $loop->feed_fd_event ($fd, $revents)
		353
		354	Feed an event on a file descriptor into EV. EV will react to this call as
		355	if the readyness notifications specified by C<$revents> (a combination of
		356	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		357
		358	=item EV::feed_signal_event ($signal)
		359
		360	Feed a signal event into EV. EV will react to this call as if the signal
		361	specified by C<$signal> had occured.
		362
		363	=item EV::set_io_collect_interval $time
		364
		365	=item $loop->set_io_collect_interval ($time)
		366
		367	=item EV::set_timeout_collect_interval $time
		368
		369	=item $loop->set_timeout_collect_interval ($time)
		370
		371	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		372	wait interval for timer events. See the libev documentation at
		373	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		374	(locally installed as F<EV::libev>) for a more detailed discussion.
		375
		376	=item $count = EV::pending_count
		377
		378	=item $count = $loop->pending_count
		379
		380	Returns the number of currently pending watchers.
		381
		382	=item EV::invoke_pending
		383
		384	=item $loop->invoke_pending
		385
		386	Invoke all currently pending watchers.
		387
		388	=back
		389
		390
		391	=head1 WATCHER OBJECTS
130		392
131	A watcher is an object that gets created to record your interest in some	393	A watcher is an object that gets created to record your interest in some
132	event. For instance, if you want to wait for STDIN to become readable, you	394	event. For instance, if you want to wait for STDIN to become readable, you
133	would create an EV::io watcher for that:	395	would create an EV::io watcher for that:
134		396
135	my $watcher = EV::io *STDIN, EV::READ, sub {	397	my $watcher = EV::io *STDIN, EV::READ, sub {
136	my ($watcher, $revents) = @_;	398	my ($watcher, $revents) = @_;
137	warn "yeah, STDIN should not be readable without blocking!\n"	399	warn "yeah, STDIN should now be readable without blocking!\n"
138	};	400	};
139		401
140	All watchers can be active (waiting for events) or inactive (paused). Only	402	All watchers can be active (waiting for events) or inactive (paused). Only
141	active watchers will have their callbacks invoked. All callbacks will be	403	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	404	called with at least two arguments: the watcher and a bitmask of received
143	events.	405	events.
144		406
145	Each watcher type has its associated bit in revents, so you can use the	407	Each watcher type has its associated bit in revents, so you can use the
146	same callback for multiple watchers. The event mask is named after the	408	same callback for multiple watchers. The event mask is named after the
147	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,	409	type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events	410	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which	411	(which can set both EV::READ and EV::WRITE bits).
150	uses EV::TIMEOUT).
151		412
152	In the rare case where one wants to create a watcher but not start it at	413	In the rare case where one wants to create a watcher but not start it at
153	the same time, each constructor has a variant with a trailing C<_ns> in	414	the same time, each constructor has a variant with a trailing C<_ns> in
154	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.	415	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
155		416
…		…
159		420
160	Also, all methods changing some aspect of a watcher (->set, ->priority,	421	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,	422	->fh and so on) automatically stop and start it again if it is active,
162	which means pending events get lost.	423	which means pending events get lost.
163		424
164	=head2 WATCHER TYPES	425	=head2 COMMON WATCHER METHODS
165		426
166	Now lets move to the existing watcher types and asociated methods.	427	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		428
173	=over 4	429	=over 4
174		430
175	=item $w->start	431	=item $w->start
176		432
…		…
180		436
181	=item $w->stop	437	=item $w->stop
182		438
183	Stop a watcher if it is active. Also clear any pending events (events that	439	Stop a watcher if it is active. Also clear any pending events (events that
184	have been received but that didn't yet result in a callback invocation),	440	have been received but that didn't yet result in a callback invocation),
185	regardless of wether the watcher was active or not.	441	regardless of whether the watcher was active or not.
186		442
187	=item $bool = $w->is_active	443	=item $bool = $w->is_active
188		444
189	Returns true if the watcher is active, false otherwise.	445	Returns true if the watcher is active, false otherwise.
190		446
…		…
215	watchers with higher priority will be invoked first. The valid range of	471	watchers with higher priority will be invoked first. The valid range of
216	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default	472	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
217	-2). If the priority is outside this range it will automatically be	473	-2). If the priority is outside this range it will automatically be
218	normalised to the nearest valid priority.	474	normalised to the nearest valid priority.
219		475
220	The default priority of any newly-created weatcher is 0.	476	The default priority of any newly-created watcher is 0.
221		477
		478	Note that the priority semantics have not yet been fleshed out and are
		479	subject to almost certain change.
		480
222	=item $w->trigger ($revents)	481	=item $w->invoke ($revents)
223		482
224	Call the callback now with the given event mask.	483	Call the callback now with the given event mask.
225		484
		485	=item $w->feed_event ($revents)
		486
		487	Feed some events on this watcher into EV. EV will react to this call as if
		488	the watcher had received the given C<$revents> mask.
		489
		490	=item $revents = $w->clear_pending
		491
		492	If the watcher is pending, this function clears its pending status and
		493	returns its C<$revents> bitset (as if its callback was invoked). If the
		494	watcher isn't pending it does nothing and returns C<0>.
		495
		496	=item $previous_state = $w->keepalive ($bool)
		497
		498	Normally, C<EV::loop> will return when there are no active watchers
		499	(which is a "deadlock" because no progress can be made anymore). This is
		500	convenient because it allows you to start your watchers (and your jobs),
		501	call C<EV::loop> once and when it returns you know that all your jobs are
		502	finished (or they forgot to register some watchers for their task :).
		503
		504	Sometimes, however, this gets in your way, for example when the module
		505	that calls C<EV::loop> (usually the main program) is not the same module
		506	as a long-living watcher (for example a DNS client module written by
		507	somebody else even). Then you might want any outstanding requests to be
		508	handled, but you would not want to keep C<EV::loop> from returning just
		509	because you happen to have this long-running UDP port watcher.
		510
		511	In this case you can clear the keepalive status, which means that even
		512	though your watcher is active, it won't keep C<EV::loop> from returning.
		513
		514	The initial value for keepalive is true (enabled), and you can change it
		515	any time.
		516
		517	Example: Register an I/O watcher for some UDP socket but do not keep the
		518	event loop from running just because of that watcher.
		519
		520	my $udp_socket = ...
		521	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		522	$udp_watcher->keepalive (0);
		523
		524	=item $loop = $w->loop
		525
		526	Return the loop that this watcher is attached to.
		527
		528	=back
		529
		530
		531	=head1 WATCHER TYPES
		532
		533	Each of the following subsections describes a single watcher type.
		534
		535	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		536
		537	=over 4
226		538
227	=item $w = EV::io $fileno_or_fh, $eventmask, $callback	539	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
228		540
229	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	541	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
230		542
		543	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		544
		545	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
		546
231	As long as the returned watcher object is alive, call the C<$callback>	547	As long as the returned watcher object is alive, call the C<$callback>
232	when the events specified in C<$eventmask>.	548	when at least one of events specified in C<$eventmask> occurs.
233		549
234	The $eventmask can be one or more of these constants ORed together:	550	The $eventmask can be one or more of these constants ORed together:
235		551
236	EV::READ wait until read() wouldn't block anymore	552	EV::READ wait until read() wouldn't block anymore
237	EV::WRITE wait until write() wouldn't block anymore	553	EV::WRITE wait until write() wouldn't block anymore
…		…
253		569
254	=item $old_eventmask = $w->events ($new_eventmask)	570	=item $old_eventmask = $w->events ($new_eventmask)
255		571
256	Returns the previously set event mask and optionally set a new one.	572	Returns the previously set event mask and optionally set a new one.
257		573
		574	=back
		575
		576
		577	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		578
		579	=over 4
258		580
259	=item $w = EV::timer $after, $repeat, $callback	581	=item $w = EV::timer $after, $repeat, $callback
260		582
261	=item $w = EV::timer_ns $after, $repeat, $callback	583	=item $w = EV::timer_ns $after, $repeat, $callback
262		584
263	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,	585	=item $w = $loop->timer ($after, $repeat, $callback)
264	the timer will be restarted (with the $repeat value as $after) after the	586
265	callback returns.	587	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		588
		589	Calls the callback after C<$after> seconds (which may be fractional). If
		590	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		591	value as $after) after the callback returns.
266		592
267	This means that the callback would be called roughly after C<$after>	593	This means that the callback would be called roughly after C<$after>
268	seconds, and then every C<$repeat> seconds. "Roughly" because the time of	594	seconds, and then every C<$repeat> seconds. The timer does his best not
269	callback processing is not taken into account, so the timer will slowly	595	to drift, but it will not invoke the timer more often then once per event
270	drift. If that isn't acceptable, look at EV::periodic.	596	loop iteration, and might drift in other cases. If that isn't acceptable,
		597	look at EV::periodic, which can provide long-term stable timers.
271		598
272	The timer is based on a monotonic clock, that is if somebody is sitting	599	The timer is based on a monotonic clock, that is, if somebody is sitting
273	in front of the machine while the timer is running and changes the system	600	in front of the machine while the timer is running and changes the system
274	clock, the timer will nevertheless run (roughly) the same time.	601	clock, the timer will nevertheless run (roughly) the same time.
275		602
276	The C<timer_ns> variant doesn't start (activate) the newly created watcher.	603	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
277		604
278	=item $w->set ($after, $repeat)	605	=item $w->set ($after, $repeat)
279		606
280	Reconfigures the watcher, see the constructor above for details. Can be at	607	Reconfigures the watcher, see the constructor above for details. Can be called at
281	any time.	608	any time.
282		609
283	=item $w->again	610	=item $w->again
284		611
285	Similar to the C<start> method, but has special semantics for repeating timers:	612	Similar to the C<start> method, but has special semantics for repeating timers:
		613
		614	If the timer is active and non-repeating, it will be stopped.
286		615
287	If the timer is active and repeating, reset the timeout to occur	616	If the timer is active and repeating, reset the timeout to occur
288	C<$repeat> seconds after now.	617	C<$repeat> seconds after now.
289		618
290	If the timer is active and non-repeating, it will be stopped.
291
292	If the timer is in active and repeating, start it.	619	If the timer is inactive and repeating, start it using the repeat value.
293		620
294	Otherwise do nothing.	621	Otherwise do nothing.
295		622
296	This behaviour is useful when you have a timeout for some IO	623	This behaviour is useful when you have a timeout for some IO
297	operation. You create a timer object with the same value for C<$after> and	624	operation. You create a timer object with the same value for C<$after> and
298	C<$repeat>, and then, in the read/write watcher, run the C<again> method	625	C<$repeat>, and then, in the read/write watcher, run the C<again> method
299	on the timeout.	626	on the timeout.
300		627
		628	=back
		629
		630
		631	=head3 PERIODIC WATCHERS - to cron or not to cron?
		632
		633	=over 4
301		634
302	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback	635	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
303		636
304	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback	637	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		638
		639	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		640
		641	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305		642
306	Similar to EV::timer, but is not based on relative timeouts but on	643	Similar to EV::timer, but is not based on relative timeouts but on
307	absolute times. Apart from creating "simple" timers that trigger "at" the	644	absolute times. Apart from creating "simple" timers that trigger "at" the
308	specified time, it can also be used for non-drifting absolute timers and	645	specified time, it can also be used for non-drifting absolute timers and
309	more complex, cron-like, setups that are not adversely affected by time	646	more complex, cron-like, setups that are not adversely affected by time
…		…
319	This time simply fires at the wallclock time C<$at> and doesn't repeat. It	656	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
320	will not adjust when a time jump occurs, that is, if it is to be run	657	will not adjust when a time jump occurs, that is, if it is to be run
321	at January 1st 2011 then it will run when the system time reaches or	658	at January 1st 2011 then it will run when the system time reaches or
322	surpasses this time.	659	surpasses this time.
323		660
324	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)	661	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
325		662
326	In this mode the watcher will always be scheduled to time out at the	663	In this mode the watcher will always be scheduled to time out at the
327	next C<$at + N * $interval> time (for some integer N) and then repeat,	664	next C<$at + N * $interval> time (for some integer N) and then repeat,
328	regardless of any time jumps.	665	regardless of any time jumps.
329		666
…		…
341	possible time where C<$time = $at (mod $interval)>, regardless of any time	678	possible time where C<$time = $at (mod $interval)>, regardless of any time
342	jumps.	679	jumps.
343		680
344	=item * manual reschedule mode ($reschedule_cb = coderef)	681	=item * manual reschedule mode ($reschedule_cb = coderef)
345		682
346	In this mode $interval and $at are both being ignored. Instead, each time	683	In this mode $interval and $at are both being ignored. Instead, each
347	the periodic watcher gets scheduled, the first callback ($reschedule_cb)	684	time the periodic watcher gets scheduled, the reschedule callback
348	will be called with the watcher as first, and the current time as second	685	($reschedule_cb) will be called with the watcher as first, and the current
349	argument.	686	time as second argument.
350		687
351	I<This callback MUST NOT stop or destroy this or any other periodic	688	I<This callback MUST NOT stop or destroy this or any other periodic
352	watcher, ever>. If you need to stop it, return 1e30 and stop it	689	watcher, ever, and MUST NOT call any event loop functions or methods>. If
353	afterwards.	690	you need to stop it, return 1e30 and stop it afterwards. You may create
		691	and start a C<EV::prepare> watcher for this task.
354		692
355	It must return the next time to trigger, based on the passed time value	693	It must return the next time to trigger, based on the passed time value
356	(that is, the lowest time value larger than to the second argument). It	694	(that is, the lowest time value larger than or equal to to the second
357	will usually be called just before the callback will be triggered, but	695	argument). It will usually be called just before the callback will be
358	might be called at other times, too.	696	triggered, but might be called at other times, too.
359		697
360	This can be used to create very complex timers, such as a timer that	698	This can be used to create very complex timers, such as a timer that
361	triggers on each midnight, local time (actually 24 hours after the last	699	triggers on each midnight, local time (actually 24 hours after the last
362	midnight, to keep the example simple. If you know a way to do it correctly	700	midnight, to keep the example simple. If you know a way to do it correctly
363	in about the same space (without requiring elaborate modules), drop me a	701	in about the same space (without requiring elaborate modules), drop me a
…		…
377		715
378	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.	716	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
379		717
380	=item $w->set ($at, $interval, $reschedule_cb)	718	=item $w->set ($at, $interval, $reschedule_cb)
381		719
382	Reconfigures the watcher, see the constructor above for details. Can be at	720	Reconfigures the watcher, see the constructor above for details. Can be called at
383	any time.	721	any time.
384		722
385	=item $w->again	723	=item $w->again
386		724
387	Simply stops and starts the watcher again.	725	Simply stops and starts the watcher again.
388		726
		727	=item $time = $w->at
		728
		729	Return the time that the watcher is expected to trigger next.
		730
		731	=back
		732
		733
		734	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		735
		736	=over 4
389		737
390	=item $w = EV::signal $signal, $callback	738	=item $w = EV::signal $signal, $callback
391		739
392	=item $w = EV::signal_ns $signal, $callback	740	=item $w = EV::signal_ns $signal, $callback
393		741
		742	=item $w = $loop->signal ($signal, $callback)
		743
		744	=item $w = $loop->signal_ns ($signal, $callback)
		745
394	Call the callback when $signal is received (the signal can be specified	746	Call the callback when $signal is received (the signal can be specified by
395	by number or by name, just as with kill or %SIG).	747	number or by name, just as with C<kill> or C<%SIG>).
		748
		749	Only one event loop can grab a given signal - attempting to grab the same
		750	signal from two EV loops will crash the program immediately or cause data
		751	corruption.
396		752
397	EV will grab the signal for the process (the kernel only allows one	753	EV will grab the signal for the process (the kernel only allows one
398	component to receive a signal at a time) when you start a signal watcher,	754	component to receive a signal at a time) when you start a signal watcher,
399	and removes it again when you stop it. Perl does the same when you	755	and removes it again when you stop it. Perl does the same when you
400	add/remove callbacks to %SIG, so watch out.	756	add/remove callbacks to C<%SIG>, so watch out.
401		757
402	You can have as many signal watchers per signal as you want.	758	You can have as many signal watchers per signal as you want.
403		759
404	The C<signal_ns> variant doesn't start (activate) the newly created watcher.	760	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
405		761
406	=item $w->set ($signal)	762	=item $w->set ($signal)
407		763
408	Reconfigures the watcher, see the constructor above for details. Can be at	764	Reconfigures the watcher, see the constructor above for details. Can be
409	any time.	765	called at any time.
410		766
411	=item $current_signum = $w->signal	767	=item $current_signum = $w->signal
412		768
413	=item $old_signum = $w->signal ($new_signal)	769	=item $old_signum = $w->signal ($new_signal)
414		770
415	Returns the previously set signal (always as a number not name) and	771	Returns the previously set signal (always as a number not name) and
416	optionally set a new one.	772	optionally set a new one.
417		773
		774	=back
418		775
		776
		777	=head3 CHILD WATCHERS - watch out for process status changes
		778
		779	=over 4
		780
419	=item $w = EV::child $pid, $callback	781	=item $w = EV::child $pid, $trace, $callback
420		782
421	=item $w = EV::child_ns $pid, $callback	783	=item $w = EV::child_ns $pid, $trace, $callback
		784
		785	=item $w = $loop->child ($pid, $trace, $callback)
		786
		787	=item $w = $loop->child_ns ($pid, $trace, $callback)
422		788
423	Call the callback when a status change for pid C<$pid> (or any pid	789	Call the callback when a status change for pid C<$pid> (or any pid
424	if C<$pid> is 0) has been received. More precisely: when the process	790	if C<$pid> is 0) has been received (a status change happens when the
		791	process terminates or is killed, or, when trace is true, additionally when
		792	it is stopped or continued). More precisely: when the process receives
425	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all	793	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
426	changed/zombie children and call the callback.	794	changed/zombie children and call the callback.
427		795
428	You can access both status and pid by using the C<rstatus> and C<rpid>	796	It is valid (and fully supported) to install a child watcher after a child
429	methods on the watcher object.	797	has exited but before the event loop has started its next iteration (for
		798	example, first you C<fork>, then the new child process might exit, and
		799	only then do you install a child watcher in the parent for the new pid).
430		800
		801	You can access both exit (or tracing) status and pid by using the
		802	C<rstatus> and C<rpid> methods on the watcher object.
		803
431	You can have as many pid watchers per pid as you want.	804	You can have as many pid watchers per pid as you want, they will all be
		805	called.
432		806
433	The C<child_ns> variant doesn't start (activate) the newly created watcher.	807	The C<child_ns> variant doesn't start (activate) the newly created watcher.
434		808
435	=item $w->set ($pid)	809	=item $w->set ($pid, $trace)
436		810
437	Reconfigures the watcher, see the constructor above for details. Can be at	811	Reconfigures the watcher, see the constructor above for details. Can be called at
438	any time.	812	any time.
439		813
440	=item $current_pid = $w->pid	814	=item $current_pid = $w->pid
441
442	=item $old_pid = $w->pid ($new_pid)
443		815
444	Returns the previously set process id and optionally set a new one.	816	Returns the previously set process id and optionally set a new one.
445		817
446	=item $exit_status = $w->rstatus	818	=item $exit_status = $w->rstatus
447		819
…		…
451	=item $pid = $w->rpid	823	=item $pid = $w->rpid
452		824
453	Return the pid of the awaited child (useful when you have installed a	825	Return the pid of the awaited child (useful when you have installed a
454	watcher for all pids).	826	watcher for all pids).
455		827
		828	=back
		829
		830
		831	=head3 STAT WATCHERS - did the file attributes just change?
		832
		833	=over 4
		834
		835	=item $w = EV::stat $path, $interval, $callback
		836
		837	=item $w = EV::stat_ns $path, $interval, $callback
		838
		839	=item $w = $loop->stat ($path, $interval, $callback)
		840
		841	=item $w = $loop->stat_ns ($path, $interval, $callback)
		842
		843	Call the callback when a file status change has been detected on
		844	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		845	to "path does not exist" is a status change like any other.
		846
		847	The C<$interval> is a recommended polling interval for systems where
		848	OS-supported change notifications don't exist or are not supported. If
		849	you use C<0> then an unspecified default is used (which is highly
		850	recommended!), which is to be expected to be around five seconds usually.
		851
		852	This watcher type is not meant for massive numbers of stat watchers,
		853	as even with OS-supported change notifications, this can be
		854	resource-intensive.
		855
		856	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		857
		858	=item ... = $w->stat
		859
		860	This call is very similar to the perl C<stat> built-in: It stats (using
		861	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		862	well as EV's idea of the current stat values) to the values found.
		863
		864	In scalar context, a boolean is return indicating success or failure of
		865	the stat. In list context, the same 13-value list as with stat is returned
		866	(except that the blksize and blocks fields are not reliable).
		867
		868	In the case of an error, errno is set to C<ENOENT> (regardless of the
		869	actual error value) and the C<nlink> value is forced to zero (if the stat
		870	was successful then nlink is guaranteed to be non-zero).
		871
		872	See also the next two entries for more info.
		873
		874	=item ... = $w->attr
		875
		876	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		877	the values most recently detected by EV. See the next entry for more info.
		878
		879	=item ... = $w->prev
		880
		881	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		882	the previous set of values, before the change.
		883
		884	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		885	to the values found I<before> a change was detected, while C<< $w->attr >>
		886	returns the values found leading to the change detection. The difference (if any)
		887	between C<prev> and C<attr> is what triggered the callback.
		888
		889	If you did something to the filesystem object and do not want to trigger
		890	yet another change, you can call C<stat> to update EV's idea of what the
		891	current attributes are.
		892
		893	=item $w->set ($path, $interval)
		894
		895	Reconfigures the watcher, see the constructor above for details. Can be
		896	called at any time.
		897
		898	=item $current_path = $w->path
		899
		900	=item $old_path = $w->path ($new_path)
		901
		902	Returns the previously set path and optionally set a new one.
		903
		904	=item $current_interval = $w->interval
		905
		906	=item $old_interval = $w->interval ($new_interval)
		907
		908	Returns the previously set interval and optionally set a new one. Can be
		909	used to query the actual interval used.
		910
		911	=back
		912
		913
		914	=head3 IDLE WATCHERS - when you've got nothing better to do...
		915
		916	=over 4
456		917
457	=item $w = EV::idle $callback	918	=item $w = EV::idle $callback
458		919
459	=item $w = EV::idle_ns $callback	920	=item $w = EV::idle_ns $callback
460		921
461	Call the callback when there are no pending io, timer/periodic, signal or	922	=item $w = $loop->idle ($callback)
462	child events, i.e. when the process is idle.	923
		924	=item $w = $loop->idle_ns ($callback)
		925
		926	Call the callback when there are no other pending watchers of the same or
		927	higher priority (excluding check, prepare and other idle watchers of the
		928	same or lower priority, of course). They are called idle watchers because
		929	when the watcher is the highest priority pending event in the process, the
		930	process is considered to be idle at that priority.
		931
		932	If you want a watcher that is only ever called when I<no> other events are
		933	outstanding you have to set the priority to C<EV::MINPRI>.
463		934
464	The process will not block as long as any idle watchers are active, and	935	The process will not block as long as any idle watchers are active, and
465	they will be called repeatedly until stopped.	936	they will be called repeatedly until stopped.
466		937
		938	For example, if you have idle watchers at priority C<0> and C<1>, and
		939	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		940	and the I/O watcher will always run when ready. Only when the idle watcher
		941	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		942	pending with the C<0>-priority idle watcher be invoked.
		943
467	The C<idle_ns> variant doesn't start (activate) the newly created watcher.	944	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
468		945
		946	=back
		947
		948
		949	=head3 PREPARE WATCHERS - customise your event loop!
		950
		951	=over 4
469		952
470	=item $w = EV::prepare $callback	953	=item $w = EV::prepare $callback
471		954
472	=item $w = EV::prepare_ns $callback	955	=item $w = EV::prepare_ns $callback
		956
		957	=item $w = $loop->prepare ($callback)
		958
		959	=item $w = $loop->prepare_ns ($callback)
473		960
474	Call the callback just before the process would block. You can still	961	Call the callback just before the process would block. You can still
475	create/modify any watchers at this point.	962	create/modify any watchers at this point.
476		963
477	See the EV::check watcher, below, for explanations and an example.	964	See the EV::check watcher, below, for explanations and an example.
478		965
479	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.	966	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
480		967
		968	=back
		969
		970
		971	=head3 CHECK WATCHERS - customise your event loop even more!
		972
		973	=over 4
481		974
482	=item $w = EV::check $callback	975	=item $w = EV::check $callback
483		976
484	=item $w = EV::check_ns $callback	977	=item $w = EV::check_ns $callback
		978
		979	=item $w = $loop->check ($callback)
		980
		981	=item $w = $loop->check_ns ($callback)
485		982
486	Call the callback just after the process wakes up again (after it has	983	Call the callback just after the process wakes up again (after it has
487	gathered events), but before any other callbacks have been invoked.	984	gathered events), but before any other callbacks have been invoked.
488		985
489	This is used to integrate other event-based software into the EV	986	This can be used to integrate other event-based software into the EV
490	mainloop: You register a prepare callback and in there, you create io and	987	mainloop: You register a prepare callback and in there, you create io and
491	timer watchers as required by the other software. Here is a real-world	988	timer watchers as required by the other software. Here is a real-world
492	example of integrating Net::SNMP (with some details left out):	989	example of integrating Net::SNMP (with some details left out):
493		990
494	our @snmp_watcher;	991	our @snmp_watcher;
…		…
497	# do nothing unless active	994	# do nothing unless active
498	$dispatcher->{_event_queue_h}	995	$dispatcher->{_event_queue_h}
499	or return;	996	or return;
500		997
501	# make the dispatcher handle any outstanding stuff	998	# make the dispatcher handle any outstanding stuff
		999	... not shown
502		1000
503	# create an IO watcher for each and every socket	1001	# create an I/O watcher for each and every socket
504	@snmp_watcher = (	1002	@snmp_watcher = (
505	(map { EV::io $_, EV::READ, sub { } }	1003	(map { EV::io $_, EV::READ, sub { } }
506	keys %{ $dispatcher->{_descriptors} }),	1004	keys %{ $dispatcher->{_descriptors} }),
		1005
		1006	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		1007	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		1008	0, sub { },
507	);	1009	);
508
509	# if there are any timeouts, also create a timer
510	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
511	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
512	};	1010	};
513		1011
514	The callbacks are irrelevant, the only purpose of those watchers is	1012	The callbacks are irrelevant (and are not even being called), the
515	to wake up the process as soon as one of those events occurs (socket	1013	only purpose of those watchers is to wake up the process as soon as
516	readable, or timer timed out). The corresponding EV::check watcher will then	1014	one of those events occurs (socket readable, or timer timed out). The
517	clean up:	1015	corresponding EV::check watcher will then clean up:
518		1016
519	our $snmp_check = EV::check sub {	1017	our $snmp_check = EV::check sub {
520	# destroy all watchers	1018	# destroy all watchers
521	@snmp_watcher = ();	1019	@snmp_watcher = ();
522		1020
523	# make the dispatcher handle any new stuff	1021	# make the dispatcher handle any new stuff
		1022	... not shown
524	};	1023	};
525		1024
526	The callbacks of the created watchers will not be called as the watchers	1025	The callbacks of the created watchers will not be called as the watchers
527	are destroyed before this cna happen (remember EV::check gets called	1026	are destroyed before this can happen (remember EV::check gets called
528	first).	1027	first).
529		1028
530	The C<check_ns> variant doesn't start (activate) the newly created watcher.	1029	The C<check_ns> variant doesn't start (activate) the newly created watcher.
531		1030
532	=back	1031	=item EV::CHECK constant issues
533		1032
		1033	Like all other watcher types, there is a bitmask constant for use in
		1034	C<$revents> and other places. The C<EV::CHECK> is special as it has
		1035	the same name as the C<CHECK> sub called by Perl. This doesn't cause
		1036	big issues on newer perls (beginning with 5.8.9), but it means thatthe
		1037	constant must be I<inlined>, i.e. runtime calls will not work. That means
		1038	that as long as you always C<use EV> and then C<EV::CHECK> you are on the
		1039	safe side.
		1040
		1041	=back
		1042
		1043
		1044	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		1045
		1046	Fork watchers are called when a C<fork ()> was detected. The invocation
		1047	is done before the event loop blocks next and before C<check> watchers
		1048	are being called, and only in the child after the fork.
		1049
		1050	=over 4
		1051
		1052	=item $w = EV::fork $callback
		1053
		1054	=item $w = EV::fork_ns $callback
		1055
		1056	=item $w = $loop->fork ($callback)
		1057
		1058	=item $w = $loop->fork_ns ($callback)
		1059
		1060	Call the callback before the event loop is resumed in the child process
		1061	after a fork.
		1062
		1063	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		1064
		1065	=back
		1066
		1067
		1068	=head3 EMBED WATCHERS - when one backend isn't enough...
		1069
		1070	This is a rather advanced watcher type that lets you embed one event loop
		1071	into another (currently only IO events are supported in the embedded
		1072	loop, other types of watchers might be handled in a delayed or incorrect
		1073	fashion and must not be used).
		1074
		1075	See the libev documentation at
		1076	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1077	(locally installed as F<EV::libev>) for more details.
		1078
		1079	In short, this watcher is most useful on BSD systems without working
		1080	kqueue to still be able to handle a large number of sockets:
		1081
		1082	my $socket_loop;
		1083
		1084	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1085	if (
		1086	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1087	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1088	) {
		1089	# use kqueue for sockets
		1090	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1091	}
		1092
		1093	# use the default loop otherwise
		1094	$socket_loop \|\|= EV::default_loop;
		1095
		1096	=over 4
		1097
		1098	=item $w = EV::embed $otherloop[, $callback]
		1099
		1100	=item $w = EV::embed_ns $otherloop[, $callback]
		1101
		1102	=item $w = $loop->embed ($otherloop[, $callback])
		1103
		1104	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1105
		1106	Call the callback when the embedded event loop (C<$otherloop>) has any
		1107	I/O activity. The C<$callback> is optional: if it is missing, then the
		1108	embedded event loop will be managed automatically (which is recommended),
		1109	otherwise you have to invoke C<sweep> yourself.
		1110
		1111	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1112
		1113	=back
		1114
		1115	=head3 ASYNC WATCHERS - how to wake up another event loop
		1116
		1117	Async watchers are provided by EV, but have little use in perl directly,
		1118	as perl neither supports threads running in parallel nor direct access to
		1119	signal handlers or other contexts where they could be of value.
		1120
		1121	It is, however, possible to use them from the XS level.
		1122
		1123	Please see the libev documentation for further details.
		1124
		1125	=over 4
		1126
		1127	=item $w = EV::async $callback
		1128
		1129	=item $w = EV::async_ns $callback
		1130
		1131	=item $w->send
		1132
		1133	=item $bool = $w->async_pending
		1134
		1135	=back
		1136
		1137
		1138	=head1 PERL SIGNALS
		1139
		1140	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1141	with EV is as the same as any other C library: Perl-signals will only be
		1142	handled when Perl runs, which means your signal handler might be invoked
		1143	only the next time an event callback is invoked.
		1144
		1145	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1146	ensure proper operations with regards to other event watchers.
		1147
		1148	If you cannot do this for whatever reason, you can also force a watcher
		1149	to be called on every event loop iteration by installing a C<EV::check>
		1150	watcher:
		1151
		1152	my $async_check = EV::check sub { };
		1153
		1154	This ensures that perl gets into control for a short time to handle any
		1155	pending signals, and also ensures (slightly) slower overall operation.
		1156
534	=head1 THREADS	1157	=head1 ITHREADS
535		1158
536	Threads are not supported by this in any way. Perl pseudo-threads is evil	1159	Ithreads are not supported by this module in any way. Perl pseudo-threads
537	stuff and must die.	1160	is evil stuff and must die. Real threads as provided by Coro are fully
		1161	supported (and enhanced support is available via L<Coro::EV>).
		1162
		1163	=head1 FORK
		1164
		1165	Most of the "improved" event delivering mechanisms of modern operating
		1166	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1167	not supported and usually destructive). Libev makes it possible to work
		1168	around this by having a function that recreates the kernel state after
		1169	fork in the child.
		1170
		1171	On non-win32 platforms, this module requires the pthread_atfork
		1172	functionality to do this automatically for you. This function is quite
		1173	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		1174	negligible, because everything the function currently does is set a flag
		1175	that is checked only when the event loop gets used the next time, so when
		1176	you do fork but not use EV, the overhead is minimal.
		1177
		1178	On win32, there is no notion of fork so all this doesn't apply, of course.
538		1179
539	=cut	1180	=cut
540		1181
541	our $DIED = sub {	1182	our $DIED = sub {
542	warn "EV: error in callback (ignoring): $@";	1183	warn "EV: error in callback (ignoring): $@";
543	};	1184	};
544		1185
545	default_loop	1186	default_loop
546	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';	1187	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
547		1188
548	1;	1189	1;
549		1190
550	=head1 SEE ALSO	1191	=head1 SEE ALSO
551		1192
552	L<EV::DNS>, L<EV::AnyEvent>.	1193	L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
		1194	(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
		1195	loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
		1196	integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1197	event-loop agnostic and portable event driven programming.
553		1198
554	=head1 AUTHOR	1199	=head1 AUTHOR
555		1200
556	Marc Lehmann <schmorp@schmorp.de>	1201	Marc Lehmann <schmorp@schmorp.de>
557	http://home.schmorp.de/	1202	http://home.schmorp.de/
558		1203
559	=cut	1204	=cut
560		1205

Diff Legend

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

Comparing EV/EV.pm (file contents): Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs. Revision 1.131 by root, Sun Dec 5 11:45:22 2010 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.34 by root, Fri Nov 9 19:38:56 2007 UTC vs.
Revision 1.131 by root, Sun Dec 5 11:45:22 2010 UTC