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

Comparing EV/EV.pm (file contents):
Revision 1.15 by root, Wed Oct 31 18:28:00 2007 UTC vs.
Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	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	# TIMER	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::timer_abs 0, 60, sub {
22	warn "is called every minute, on the minute, exactly";
23	};
24
25	# IO
26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothing received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};
35	$w->timeout (10);
36
37	my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
38	my ($w, $events) = @_;	47	my ($w, $revents) = @_;
39	if ($_[1] & EV::TIMEOUT) {	48	warn $w->path, " has changed somehow.\n";
40	warn "nothing entered within 30 seconds, bye bye.\n";
41	$w->stop;
42	} else {
43	my $line = <STDIN>;
44	warn "you entered something, you again have 30 seconds.\n";
45	}
46	};	49	};
47		50
48	# SIGNALS
49
50	my $w = EV::signal 'QUIT', sub {
51	warn "sigquit received\n";
52	};
53
54	my $w = EV::signal 3, sub {
55	warn "sigquit received (this is GNU/Linux, right?)\n";
56	};
57
58	# MAINLOOP	51	# MAINLOOP
59	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
60	EV::loop; # the same thing
61	EV::loop EV::LOOP_ONCE; # block until some events could be handles	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
62	EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait	54	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
63		55
64	=head1 DESCRIPTION	56	=head1 DESCRIPTION
65		57
66	This module provides an interface to libevent	58	This module provides an interface to libev
67	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
68	yourself with its documentation and source code to be able to use this	60	below is comprehensive, one might also consult the documentation of
69	module fully.	61	libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
		62	F<perldoc EV::libev>) for more subtle details on watcher semantics or some
		63	discussion on the available backends, or how to force a specific backend
		64	with C<LIBEV_FLAGS>, or just about in any case because it has much more
		65	detailed information.
70		66
71	Please note thta this module disables the libevent EPOLL method by	67	This module is very fast and scalable. It is actually so fast that you
72	default, see BUGS, below, if you need to enable it.	68	can use it through the L<AnyEvent> module, stay portable to other event
		69	loops (if you don't rely on any watcher types not available through it)
		70	and still be faster than with any other event loop currently supported in
		71	Perl.
		72
		73	=head2 MODULE EXPORTS
		74
		75	This module does not export any symbols.
73		76
74	=cut	77	=cut
75		78
76	package EV;	79	package EV;
77		80
78	use strict;	81	use common::sense;
79		82
80	BEGIN {	83	BEGIN {
81	our $VERSION = '0.03';	84	our $VERSION = '3.6';
82	use XSLoader;	85	use XSLoader;
83	XSLoader::load "EV", $VERSION;	86	XSLoader::load "EV", $VERSION;
84	}	87	}
85		88
86	@EV::Io::ISA = "EV::Watcher";	89	@EV::IO::ISA =
87	@EV::Time::ISA = "EV::Watcher";
88	@EV::Timer::ISA = "EV::Time";	90	@EV::Timer::ISA =
89	@EV::Periodic::ISA = "EV::Time";	91	@EV::Periodic::ISA =
90	@EV::Signal::ISA = "EV::Watcher";	92	@EV::Signal::ISA =
91	@EV::Idle::ISA = "EV::Watcher";	93	@EV::Child::ISA =
92	@EV::Prepare::ISA = "EV::Watcher";	94	@EV::Stat::ISA =
93	@EV::Check::ISA = "EV::Watcher";	95	@EV::Idle::ISA =
		96	@EV::Prepare::ISA =
		97	@EV::Check::ISA =
		98	@EV::Embed::ISA =
		99	@EV::Fork::ISA =
		100	@EV::Async::ISA =
		101	"EV::Watcher";
		102
		103	@EV::Loop::Default::ISA = "EV::Loop";
		104
		105	=head1 EVENT LOOPS
		106
		107	EV supports multiple event loops: There is a single "default event loop"
		108	that can handle everything including signals and child watchers, and any
		109	number of "dynamic event loops" that can use different backends (with
		110	various limitations), but no child and signal watchers.
		111
		112	You do not have to do anything to create the default event loop: When
		113	the module is loaded a suitable backend is selected on the premise of
		114	selecting a working backend (which for example rules out kqueue on most
		115	BSDs). Modules should, unless they have "special needs" always use the
		116	default loop as this is fastest (perl-wise), best supported by other
		117	modules (e.g. AnyEvent or Coro) and most portable event loop.
		118
		119	For specific programs you can create additional event loops dynamically.
		120
		121	If you want to take advantage of kqueue (which often works properly for
		122	sockets only) even though the default loop doesn't enable it, you can
		123	I<embed> a kqueue loop into the default loop: running the default loop
		124	will then also service the kqueue loop to some extent. See the example in
		125	the section about embed watchers for an example on how to achieve that.
		126
		127	=over 4
		128
		129	=item $loop = new EV::Loop [$flags]
		130
		131	Create a new event loop as per the specified flags. Please refer to
		132	the C<ev_loop_new ()> function description in the libev documentation
		133	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
		134	or locally-installed as F<EV::libev> manpage) for more info.
		135
		136	The loop will automatically be destroyed when it is no longer referenced
		137	by any watcher and the loop object goes out of scope.
		138
		139	If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
		140	is recommended, as only the default event loop is protected by this
		141	module. If you I<are> embedding this loop in the default loop, this is not
		142	necessary, as C<EV::embed> automatically does the right thing on fork.
		143
		144	=item $loop->loop_fork
		145
		146	Must be called after a fork in the child, before entering or continuing
		147	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		148	this function automatically, at some performance loss (refer to the libev
		149	documentation).
		150
		151	=item $loop->loop_verify
		152
		153	Calls C<ev_verify> to make internal consistency checks (for debugging
		154	libev) and abort the program if any data structures were found to be
		155	corrupted.
		156
		157	=item $loop = EV::default_loop [$flags]
		158
		159	Return the default loop (which is a singleton object). Since this module
		160	already creates the default loop with default flags, specifying flags here
		161	will not have any effect unless you destroy the default loop first, which
		162	isn't supported. So in short: don't do it, and if you break it, you get to
		163	keep the pieces.
		164
		165	=back
		166
94		167
95	=head1 BASIC INTERFACE	168	=head1 BASIC INTERFACE
96		169
97	=over 4	170	=over 4
98		171
99	=item $EV::NPRI
100
101	How many priority levels are available.
102
103	=item $EV::DIED	172	=item $EV::DIED
104		173
105	Must contain a reference to a function that is called when a callback	174	Must contain a reference to a function that is called when a callback
106	throws an exception (with $@ containing thr error). The default prints an	175	throws an exception (with $@ containing the error). The default prints an
107	informative message and continues.	176	informative message and continues.
108		177
109	If this callback throws an exception it will be silently ignored.	178	If this callback throws an exception it will be silently ignored.
110		179
		180	=item $flags = EV::supported_backends
		181
		182	=item $flags = EV::recommended_backends
		183
		184	=item $flags = EV::embeddable_backends
		185
		186	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		187	instance of EV, the set of recommended backends (supposed to be good) for
		188	this platform and the set of embeddable backends (see EMBED WATCHERS).
		189
		190	=item EV::sleep $seconds
		191
		192	Block the process for the given number of (fractional) seconds.
		193
		194	=item $time = EV::time
		195
		196	Returns the current time in (fractional) seconds since the epoch.
		197
111	=item $time = EV::now	198	=item $time = EV::now
112		199
113	Returns the time in (fractional) seconds since the epoch.	200	=item $time = $loop->now
114		201
115	=item $version = EV::version	202	Returns the time the last event loop iteration has been started. This
		203	is the time that (relative) timers are based on, and referring to it is
		204	usually faster then calling EV::time.
116		205
117	=item $method = EV::method	206	=item EV::now_update
118		207
119	Return version string and event polling method used.	208	=item $loop->now_update
120		209
121	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	210	Establishes the current time by querying the kernel, updating the time
		211	returned by C<EV::now> in the progress. This is a costly operation and
		212	is usually done automatically within C<EV::loop>.
122		213
123	=item EV::loopexit $after	214	This function is rarely useful, but when some event callback runs for a
		215	very long time without entering the event loop, updating libev's idea of
		216	the current time is a good idea.
124		217
125	Exit any active loop or dispatch after C<$after> seconds or immediately if	218	=item EV::suspend
126	C<$after> is missing or zero.
127		219
128	=item EV::dispatch	220	=item $loop->suspend
129		221
130	Same as C<EV::loop 0>.	222	=item EV::resume
131		223
132	=item EV::event $callback	224	=item $loop->resume
133		225
134	Creates a new event watcher waiting for nothing, calling the given callback.	226	These two functions suspend and resume a loop, for use when the loop is
		227	not used for a while and timeouts should not be processed.
135		228
		229	A typical use case would be an interactive program such as a game: When
		230	the user presses C<^Z> to suspend the game and resumes it an hour later it
		231	would be best to handle timeouts as if no time had actually passed while
		232	the program was suspended. This can be achieved by calling C<suspend>
		233	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		234	C<resume> directly afterwards to resume timer processing.
		235
		236	Effectively, all C<timer> watchers will be delayed by the time spend
		237	between C<suspend> and C<resume>, and all C<periodic> watchers
		238	will be rescheduled (that is, they will lose any events that would have
		239	occured while suspended).
		240
		241	After calling C<suspend> you B<must not> call I<any> function on the given
		242	loop other than C<resume>, and you B<must not> call C<resume>
		243	without a previous call to C<suspend>.
		244
		245	Calling C<suspend>/C<resume> has the side effect of updating the event
		246	loop time (see C<now_update>).
		247
		248	=item $backend = EV::backend
		249
		250	=item $backend = $loop->backend
		251
		252	Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
		253	or EV::BACKEND_EPOLL).
		254
		255	=item EV::loop [$flags]
		256
		257	=item $loop->loop ([$flags])
		258
		259	Begin checking for events and calling callbacks. It returns when a
		260	callback calls EV::unloop.
		261
		262	The $flags argument can be one of the following:
		263
		264	0 as above
		265	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		266	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
		267
		268	=item EV::unloop [$how]
		269
		270	=item $loop->unloop ([$how])
		271
		272	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		273	innermost call to EV::loop return.
		274
		275	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		276	fast as possible.
		277
		278	=item $count = EV::loop_count
		279
		280	=item $count = $loop->loop_count
		281
		282	Return the number of times the event loop has polled for new
		283	events. Sometimes useful as a generation counter.
		284
		285	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		286
		287	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		288
		289	This function rolls together an I/O and a timer watcher for a single
		290	one-shot event without the need for managing a watcher object.
		291
		292	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		293	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		294	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		295	you do not want to wait for some I/O event, specify C<undef> for
		296	C<$fh_or_undef> and C<0> for C<$events>).
		297
		298	If timeout is C<undef> or negative, then there will be no
		299	timeout. Otherwise a EV::timer with this value will be started.
		300
		301	When an error occurs or either the timeout or I/O watcher triggers, then
		302	the callback will be called with the received event set (in general
		303	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		304	C<EV::WRITE> and C<EV::TIMEOUT>).
		305
		306	EV::once doesn't return anything: the watchers stay active till either
		307	of them triggers, then they will be stopped and freed, and the callback
		308	invoked.
		309
		310	=item EV::feed_fd_event ($fd, $revents)
		311
		312	=item $loop->feed_fd_event ($fd, $revents)
		313
		314	Feed an event on a file descriptor into EV. EV will react to this call as
		315	if the readyness notifications specified by C<$revents> (a combination of
		316	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		317
		318	=item EV::feed_signal_event ($signal)
		319
		320	Feed a signal event into EV. EV will react to this call as if the signal
		321	specified by C<$signal> had occured.
		322
		323	=item EV::set_io_collect_interval $time
		324
		325	=item $loop->set_io_collect_interval ($time)
		326
		327	=item EV::set_timeout_collect_interval $time
		328
		329	=item $loop->set_timeout_collect_interval ($time)
		330
		331	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		332	wait interval for timer events. See the libev documentation at
		333	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
		334	(locally installed as F<EV::libev>) for a more detailed discussion.
		335
		336	=back
		337
		338
		339	=head1 WATCHER OBJECTS
		340
		341	A watcher is an object that gets created to record your interest in some
		342	event. For instance, if you want to wait for STDIN to become readable, you
		343	would create an EV::io watcher for that:
		344
		345	my $watcher = EV::io *STDIN, EV::READ, sub {
		346	my ($watcher, $revents) = @_;
		347	warn "yeah, STDIN should now be readable without blocking!\n"
		348	};
		349
		350	All watchers can be active (waiting for events) or inactive (paused). Only
		351	active watchers will have their callbacks invoked. All callbacks will be
		352	called with at least two arguments: the watcher and a bitmask of received
		353	events.
		354
		355	Each watcher type has its associated bit in revents, so you can use the
		356	same callback for multiple watchers. The event mask is named after the
		357	type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		358	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		359	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		360	uses EV::TIMEOUT).
		361
		362	In the rare case where one wants to create a watcher but not start it at
		363	the same time, each constructor has a variant with a trailing C<_ns> in
		364	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		365
		366	Please note that a watcher will automatically be stopped when the watcher
		367	object is destroyed, so you I<need> to keep the watcher objects returned by
		368	the constructors.
		369
		370	Also, all methods changing some aspect of a watcher (->set, ->priority,
		371	->fh and so on) automatically stop and start it again if it is active,
		372	which means pending events get lost.
		373
		374	=head2 COMMON WATCHER METHODS
		375
		376	This section lists methods common to all watchers.
		377
		378	=over 4
		379
		380	=item $w->start
		381
		382	Starts a watcher if it isn't active already. Does nothing to an already
		383	active watcher. By default, all watchers start out in the active state
		384	(see the description of the C<_ns> variants if you need stopped watchers).
		385
		386	=item $w->stop
		387
		388	Stop a watcher if it is active. Also clear any pending events (events that
		389	have been received but that didn't yet result in a callback invocation),
		390	regardless of whether the watcher was active or not.
		391
		392	=item $bool = $w->is_active
		393
		394	Returns true if the watcher is active, false otherwise.
		395
		396	=item $current_data = $w->data
		397
		398	=item $old_data = $w->data ($new_data)
		399
		400	Queries a freely usable data scalar on the watcher and optionally changes
		401	it. This is a way to associate custom data with a watcher:
		402
		403	my $w = EV::timer 60, 0, sub {
		404	warn $_[0]->data;
		405	};
		406	$w->data ("print me!");
		407
		408	=item $current_cb = $w->cb
		409
		410	=item $old_cb = $w->cb ($new_cb)
		411
		412	Queries the callback on the watcher and optionally changes it. You can do
		413	this at any time without the watcher restarting.
		414
		415	=item $current_priority = $w->priority
		416
		417	=item $old_priority = $w->priority ($new_priority)
		418
		419	Queries the priority on the watcher and optionally changes it. Pending
		420	watchers with higher priority will be invoked first. The valid range of
		421	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		422	-2). If the priority is outside this range it will automatically be
		423	normalised to the nearest valid priority.
		424
		425	The default priority of any newly-created watcher is 0.
		426
		427	Note that the priority semantics have not yet been fleshed out and are
		428	subject to almost certain change.
		429
		430	=item $w->invoke ($revents)
		431
		432	Call the callback now with the given event mask.
		433
		434	=item $w->feed_event ($revents)
		435
		436	Feed some events on this watcher into EV. EV will react to this call as if
		437	the watcher had received the given C<$revents> mask.
		438
		439	=item $revents = $w->clear_pending
		440
		441	If the watcher is pending, this function clears its pending status and
		442	returns its C<$revents> bitset (as if its callback was invoked). If the
		443	watcher isn't pending it does nothing and returns C<0>.
		444
		445	=item $previous_state = $w->keepalive ($bool)
		446
		447	Normally, C<EV::loop> will return when there are no active watchers
		448	(which is a "deadlock" because no progress can be made anymore). This is
		449	convinient because it allows you to start your watchers (and your jobs),
		450	call C<EV::loop> once and when it returns you know that all your jobs are
		451	finished (or they forgot to register some watchers for their task :).
		452
		453	Sometimes, however, this gets in your way, for example when the module
		454	that calls C<EV::loop> (usually the main program) is not the same module
		455	as a long-living watcher (for example a DNS client module written by
		456	somebody else even). Then you might want any outstanding requests to be
		457	handled, but you would not want to keep C<EV::loop> from returning just
		458	because you happen to have this long-running UDP port watcher.
		459
		460	In this case you can clear the keepalive status, which means that even
		461	though your watcher is active, it won't keep C<EV::loop> from returning.
		462
		463	The initial value for keepalive is true (enabled), and you can change it
		464	any time.
		465
		466	Example: Register an I/O watcher for some UDP socket but do not keep the
		467	event loop from running just because of that watcher.
		468
		469	my $udp_socket = ...
		470	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		471	$udp_watcher->keepalive (0);
		472
		473	=item $loop = $w->loop
		474
		475	Return the loop that this watcher is attached to.
		476
		477	=back
		478
		479
		480	=head1 WATCHER TYPES
		481
		482	Each of the following subsections describes a single watcher type.
		483
		484	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		485
		486	=over 4
		487
136	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	488	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
137		489
138	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	490	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		491
		492	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		493
		494	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
139		495
140	As long as the returned watcher object is alive, call the C<$callback>	496	As long as the returned watcher object is alive, call the C<$callback>
141	when the events specified in C<$eventmask> happen. Initially, the timeout	497	when at least one of events specified in C<$eventmask> occurs.
142	is disabled.
143		498
144	You can additionall set a timeout to occur on the watcher, but note that
145	this timeout will not be reset when you get an I/O event in the EV::PERSIST
146	case, and reaching a timeout will always stop the watcher even in the
147	EV::PERSIST case.
148
149	If you want a timeout to occur only after a specific time of inactivity, set
150	a repeating timeout and do NOT use EV::PERSIST.
151
152	Eventmask can be one or more of these constants ORed together:	499	The $eventmask can be one or more of these constants ORed together:
153		500
154	EV::READ wait until read() wouldn't block anymore	501	EV::READ wait until read() wouldn't block anymore
155	EV::WRITE wait until write() wouldn't block anymore	502	EV::WRITE wait until write() wouldn't block anymore
156	EV::PERSIST stay active after a (non-timeout) event occured
157		503
158	The C<io_ns> variant doesn't add/start the newly created watcher.	504	The C<io_ns> variant doesn't start (activate) the newly created watcher.
159		505
160	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	506	=item $w->set ($fileno_or_fh, $eventmask)
161		507
162	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	508	Reconfigures the watcher, see the constructor above for details. Can be
		509	called at any time.
163		510
164	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	511	=item $current_fh = $w->fh
165	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
166	and will automatically be cleared. The watcher will be restarted after each event.
167		512
168	If the timeout is zero or undef, no timeout will be set, and a normal	513	=item $old_fh = $w->fh ($new_fh)
169	watcher (with the persist flag set!) will be created.
170		514
171	This has the effect of timing out after the specified period of inactivity	515	Returns the previously set filehandle and optionally set a new one.
172	has happened.
173		516
174	Due to the design of libevent, this is also relatively inefficient, having	517	=item $current_eventmask = $w->events
175	one or two io watchers and a separate timeout watcher that you reset on
176	activity (by calling its C<start> method) is usually more efficient.
177		518
		519	=item $old_eventmask = $w->events ($new_eventmask)
		520
		521	Returns the previously set event mask and optionally set a new one.
		522
		523	=back
		524
		525
		526	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		527
		528	=over 4
		529
178	=item my $w = EV::timer $after, $repeat, $callback	530	=item $w = EV::timer $after, $repeat, $callback
179		531
180	=item my $w = EV::timer_ns $after, $repeat, $callback	532	=item $w = EV::timer_ns $after, $repeat, $callback
181		533
182	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	534	=item $w = $loop->timer ($after, $repeat, $callback)
183	timer will be restarted after the callback returns. This means that the
184	callback would be called roughly every C<$after> seconds, prolonged by the
185	time the callback takes.
186		535
		536	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		537
		538	Calls the callback after C<$after> seconds (which may be fractional). If
		539	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		540	value as $after) after the callback returns.
		541
		542	This means that the callback would be called roughly after C<$after>
		543	seconds, and then every C<$repeat> seconds. The timer does his best not
		544	to drift, but it will not invoke the timer more often then once per event
		545	loop iteration, and might drift in other cases. If that isn't acceptable,
		546	look at EV::periodic, which can provide long-term stable timers.
		547
		548	The timer is based on a monotonic clock, that is, if somebody is sitting
		549	in front of the machine while the timer is running and changes the system
		550	clock, the timer will nevertheless run (roughly) the same time.
		551
187	The C<timer_ns> variant doesn't add/start the newly created watcher.	552	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
188		553
189	=item my $w = EV::timer_abs $at, $interval, $callback	554	=item $w->set ($after, $repeat)
190		555
191	=item my $w = EV::timer_abs_ns $at, $interval, $callback	556	Reconfigures the watcher, see the constructor above for details. Can be called at
		557	any time.
192		558
193	Similar to EV::timer, but the time is given as an absolute point in time	559	=item $w->again
194	(C<$at>), plus an optional C<$interval>.
195		560
196	If the C<$interval> is zero, then the callback will be called at the time	561	Similar to the C<start> method, but has special semantics for repeating timers:
197	C<$at> if that is in the future, or as soon as possible if its in the
198	past. It will not automatically repeat.
199		562
200	If the C<$interval> is nonzero, then the watcher will always be scheduled	563	If the timer is active and non-repeating, it will be stopped.
201	to time out at the next C<$at + integer * $interval> time.
202		564
203	This can be used to schedule a callback to run at very regular intervals,	565	If the timer is active and repeating, reset the timeout to occur
204	as long as the processing time is less then the interval (otherwise	566	C<$repeat> seconds after now.
205	obviously events will be skipped).	567
		568	If the timer is inactive and repeating, start it using the repeat value.
		569
		570	Otherwise do nothing.
		571
		572	This behaviour is useful when you have a timeout for some IO
		573	operation. You create a timer object with the same value for C<$after> and
		574	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		575	on the timeout.
		576
		577	=back
		578
		579
		580	=head3 PERIODIC WATCHERS - to cron or not to cron?
		581
		582	=over 4
		583
		584	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		585
		586	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		587
		588	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		589
		590	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		591
		592	Similar to EV::timer, but is not based on relative timeouts but on
		593	absolute times. Apart from creating "simple" timers that trigger "at" the
		594	specified time, it can also be used for non-drifting absolute timers and
		595	more complex, cron-like, setups that are not adversely affected by time
		596	jumps (i.e. when the system clock is changed by explicit date -s or other
		597	means such as ntpd). It is also the most complex watcher type in EV.
		598
		599	It has three distinct "modes":
		600
		601	=over 4
		602
		603	=item * absolute timer ($interval = $reschedule_cb = 0)
		604
		605	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		606	will not adjust when a time jump occurs, that is, if it is to be run
		607	at January 1st 2011 then it will run when the system time reaches or
		608	surpasses this time.
		609
		610	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		611
		612	In this mode the watcher will always be scheduled to time out at the
		613	next C<$at + N * $interval> time (for some integer N) and then repeat,
		614	regardless of any time jumps.
		615
		616	This can be used to create timers that do not drift with respect to system
		617	time:
		618
		619	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		620
		621	That doesn't mean there will always be 3600 seconds in between triggers,
		622	but only that the the clalback will be called when the system time shows a
		623	full hour (UTC).
206		624
207	Another way to think about it (for the mathematically inclined) is that	625	Another way to think about it (for the mathematically inclined) is that
208	C<timer_abs> will try to tun the callback at the next possible time where	626	EV::periodic will try to run the callback in this mode at the next
209	C<$time = $at (mod $interval)>, regardless of any time jumps.	627	possible time where C<$time = $at (mod $interval)>, regardless of any time
		628	jumps.
210		629
		630	=item * manual reschedule mode ($reschedule_cb = coderef)
		631
		632	In this mode $interval and $at are both being ignored. Instead, each
		633	time the periodic watcher gets scheduled, the reschedule callback
		634	($reschedule_cb) will be called with the watcher as first, and the current
		635	time as second argument.
		636
		637	I<This callback MUST NOT stop or destroy this or any other periodic
		638	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		639	you need to stop it, return 1e30 and stop it afterwards. You may create
		640	and start a C<EV::prepare> watcher for this task.
		641
		642	It must return the next time to trigger, based on the passed time value
		643	(that is, the lowest time value larger than or equal to to the second
		644	argument). It will usually be called just before the callback will be
		645	triggered, but might be called at other times, too.
		646
		647	This can be used to create very complex timers, such as a timer that
		648	triggers on each midnight, local time (actually 24 hours after the last
		649	midnight, to keep the example simple. If you know a way to do it correctly
		650	in about the same space (without requiring elaborate modules), drop me a
		651	note :):
		652
		653	my $daily = EV::periodic 0, 0, sub {
		654	my ($w, $now) = @_;
		655
		656	use Time::Local ();
		657	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		658	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		659	}, sub {
		660	print "it's midnight or likely shortly after, now\n";
		661	};
		662
		663	=back
		664
211	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	665	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
212		666
		667	=item $w->set ($at, $interval, $reschedule_cb)
		668
		669	Reconfigures the watcher, see the constructor above for details. Can be called at
		670	any time.
		671
		672	=item $w->again
		673
		674	Simply stops and starts the watcher again.
		675
		676	=item $time = $w->at
		677
		678	Return the time that the watcher is expected to trigger next.
		679
		680	=back
		681
		682
		683	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		684
		685	=over 4
		686
213	=item my $w = EV::signal $signal, $callback	687	=item $w = EV::signal $signal, $callback
214		688
215	=item my $w = EV::signal_ns $signal, $callback	689	=item $w = EV::signal_ns $signal, $callback
216		690
217	Call the callback when $signal is received (the signal can be specified	691	Call the callback when $signal is received (the signal can be specified by
218	by number or by name, just as with kill or %SIG). Signal watchers are	692	number or by name, just as with C<kill> or C<%SIG>).
219	persistent no natter what.
220		693
221	EV will grab the signal for the process (the kernel only allows one	694	EV will grab the signal for the process (the kernel only allows one
222	component to receive signals) when you start a signal watcher, and	695	component to receive a signal at a time) when you start a signal watcher,
223	removes it again when you stop it. Pelr does the same when you add/remove	696	and removes it again when you stop it. Perl does the same when you
224	callbacks to %SIG, so watch out.	697	add/remove callbacks to C<%SIG>, so watch out.
225		698
226	Unfortunately, only one handler can be registered per signal. Screw	699	You can have as many signal watchers per signal as you want.
227	libevent.
228		700
229	The C<signal_ns> variant doesn't add/start the newly created watcher.	701	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
230		702
231	=back	703	=item $w->set ($signal)
232		704
233	=head1 THE EV::Event CLASS	705	Reconfigures the watcher, see the constructor above for details. Can be
		706	called at any time.
234		707
235	All EV functions creating an event watcher (designated by C<my $w =>
236	above) support the following methods on the returned watcher object:
237
238	=over 4
239
240	=item $w->add ($timeout)
241
242	Stops and (re-)starts the event watcher, setting the optional timeout to
243	the given value, or clearing the timeout if none is given.
244
245	=item $w->start
246
247	Stops and (re-)starts the event watcher without touching the timeout.
248
249	=item $w->del
250
251	=item $w->stop
252
253	Stop the event watcher if it was started.
254
255	=item $current_callback = $w->cb
256
257	=item $old_callback = $w->cb ($new_callback)
258
259	Return the previously set callback and optionally set a new one.
260
261	=item $current_fh = $w->fh
262
263	=item $old_fh = $w->fh ($new_fh)
264
265	Returns the previously set filehandle and optionally set a new one (also
266	clears the EV::SIGNAL flag when setting a filehandle).
267
268	=item $current_signal = $w->signal	708	=item $current_signum = $w->signal
269		709
270	=item $old_signal = $w->signal ($new_signal)	710	=item $old_signum = $w->signal ($new_signal)
271		711
		712	Returns the previously set signal (always as a number not name) and
		713	optionally set a new one.
		714
		715	=back
		716
		717
		718	=head3 CHILD WATCHERS - watch out for process status changes
		719
		720	=over 4
		721
		722	=item $w = EV::child $pid, $trace, $callback
		723
		724	=item $w = EV::child_ns $pid, $trace, $callback
		725
		726	=item $w = $loop->child ($pid, $trace, $callback)
		727
		728	=item $w = $loop->child_ns ($pid, $trace, $callback)
		729
		730	Call the callback when a status change for pid C<$pid> (or any pid
		731	if C<$pid> is 0) has been received (a status change happens when the
		732	process terminates or is killed, or, when trace is true, additionally when
		733	it is stopped or continued). More precisely: when the process receives
		734	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		735	changed/zombie children and call the callback.
		736
		737	It is valid (and fully supported) to install a child watcher after a child
		738	has exited but before the event loop has started its next iteration (for
		739	example, first you C<fork>, then the new child process might exit, and
		740	only then do you install a child watcher in the parent for the new pid).
		741
		742	You can access both exit (or tracing) status and pid by using the
		743	C<rstatus> and C<rpid> methods on the watcher object.
		744
		745	You can have as many pid watchers per pid as you want, they will all be
		746	called.
		747
		748	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		749
		750	=item $w->set ($pid, $trace)
		751
		752	Reconfigures the watcher, see the constructor above for details. Can be called at
		753	any time.
		754
		755	=item $current_pid = $w->pid
		756
272	Returns the previously set signal number and optionally set a new one (also sets	757	Returns the previously set process id and optionally set a new one.
273	the EV::SIGNAL flag when setting a signal).
274		758
275	=item $current_eventmask = $w->events	759	=item $exit_status = $w->rstatus
276		760
277	=item $old_eventmask = $w->events ($new_eventmask)	761	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		762	in perlfunc).
278		763
		764	=item $pid = $w->rpid
		765
		766	Return the pid of the awaited child (useful when you have installed a
		767	watcher for all pids).
		768
		769	=back
		770
		771
		772	=head3 STAT WATCHERS - did the file attributes just change?
		773
		774	=over 4
		775
		776	=item $w = EV::stat $path, $interval, $callback
		777
		778	=item $w = EV::stat_ns $path, $interval, $callback
		779
		780	=item $w = $loop->stat ($path, $interval, $callback)
		781
		782	=item $w = $loop->stat_ns ($path, $interval, $callback)
		783
		784	Call the callback when a file status change has been detected on
		785	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		786	to "path does not exist" is a status change like any other.
		787
		788	The C<$interval> is a recommended polling interval for systems where
		789	OS-supported change notifications don't exist or are not supported. If
		790	you use C<0> then an unspecified default is used (which is highly
		791	recommended!), which is to be expected to be around five seconds usually.
		792
		793	This watcher type is not meant for massive numbers of stat watchers,
		794	as even with OS-supported change notifications, this can be
		795	resource-intensive.
		796
		797	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		798
		799	=item ... = $w->stat
		800
		801	This call is very similar to the perl C<stat> built-in: It stats (using
		802	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		803	well as EV's idea of the current stat values) to the values found.
		804
		805	In scalar context, a boolean is return indicating success or failure of
		806	the stat. In list context, the same 13-value list as with stat is returned
		807	(except that the blksize and blocks fields are not reliable).
		808
		809	In the case of an error, errno is set to C<ENOENT> (regardless of the
		810	actual error value) and the C<nlink> value is forced to zero (if the stat
		811	was successful then nlink is guaranteed to be non-zero).
		812
		813	See also the next two entries for more info.
		814
		815	=item ... = $w->attr
		816
		817	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		818	the values most recently detected by EV. See the next entry for more info.
		819
		820	=item ... = $w->prev
		821
		822	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		823	the previous set of values, before the change.
		824
		825	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		826	to the values found I<before> a change was detected, while C<< $w->attr >>
		827	returns the values found leading to the change detection. The difference (if any)
		828	between C<prev> and C<attr> is what triggered the callback.
		829
		830	If you did something to the filesystem object and do not want to trigger
		831	yet another change, you can call C<stat> to update EV's idea of what the
		832	current attributes are.
		833
		834	=item $w->set ($path, $interval)
		835
		836	Reconfigures the watcher, see the constructor above for details. Can be
		837	called at any time.
		838
		839	=item $current_path = $w->path
		840
		841	=item $old_path = $w->path ($new_path)
		842
279	Returns the previously set event mask and optionally set a new one.	843	Returns the previously set path and optionally set a new one.
280		844
281	=item $w->timeout ($after, $repeat)	845	=item $current_interval = $w->interval
282		846
283	Resets the timeout (see C<EV::timer> for details).	847	=item $old_interval = $w->interval ($new_interval)
284		848
285	=item $w->timeout_abs ($at, $interval)	849	Returns the previously set interval and optionally set a new one. Can be
		850	used to query the actual interval used.
286		851
287	Resets the timeout (see C<EV::timer_abs> for details).
288
289	=item $w->priority_set ($priority)
290
291	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
292
293	=back	852	=back
294		853
		854
		855	=head3 IDLE WATCHERS - when you've got nothing better to do...
		856
		857	=over 4
		858
		859	=item $w = EV::idle $callback
		860
		861	=item $w = EV::idle_ns $callback
		862
		863	=item $w = $loop->idle ($callback)
		864
		865	=item $w = $loop->idle_ns ($callback)
		866
		867	Call the callback when there are no other pending watchers of the same or
		868	higher priority (excluding check, prepare and other idle watchers of the
		869	same or lower priority, of course). They are called idle watchers because
		870	when the watcher is the highest priority pending event in the process, the
		871	process is considered to be idle at that priority.
		872
		873	If you want a watcher that is only ever called when I<no> other events are
		874	outstanding you have to set the priority to C<EV::MINPRI>.
		875
		876	The process will not block as long as any idle watchers are active, and
		877	they will be called repeatedly until stopped.
		878
		879	For example, if you have idle watchers at priority C<0> and C<1>, and
		880	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		881	and the I/O watcher will always run when ready. Only when the idle watcher
		882	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		883	pending with the C<0>-priority idle watcher be invoked.
		884
		885	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		886
		887	=back
		888
		889
		890	=head3 PREPARE WATCHERS - customise your event loop!
		891
		892	=over 4
		893
		894	=item $w = EV::prepare $callback
		895
		896	=item $w = EV::prepare_ns $callback
		897
		898	=item $w = $loop->prepare ($callback)
		899
		900	=item $w = $loop->prepare_ns ($callback)
		901
		902	Call the callback just before the process would block. You can still
		903	create/modify any watchers at this point.
		904
		905	See the EV::check watcher, below, for explanations and an example.
		906
		907	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		908
		909	=back
		910
		911
		912	=head3 CHECK WATCHERS - customise your event loop even more!
		913
		914	=over 4
		915
		916	=item $w = EV::check $callback
		917
		918	=item $w = EV::check_ns $callback
		919
		920	=item $w = $loop->check ($callback)
		921
		922	=item $w = $loop->check_ns ($callback)
		923
		924	Call the callback just after the process wakes up again (after it has
		925	gathered events), but before any other callbacks have been invoked.
		926
		927	This is used to integrate other event-based software into the EV
		928	mainloop: You register a prepare callback and in there, you create io and
		929	timer watchers as required by the other software. Here is a real-world
		930	example of integrating Net::SNMP (with some details left out):
		931
		932	our @snmp_watcher;
		933
		934	our $snmp_prepare = EV::prepare sub {
		935	# do nothing unless active
		936	$dispatcher->{_event_queue_h}
		937	or return;
		938
		939	# make the dispatcher handle any outstanding stuff
		940	... not shown
		941
		942	# create an I/O watcher for each and every socket
		943	@snmp_watcher = (
		944	(map { EV::io $_, EV::READ, sub { } }
		945	keys %{ $dispatcher->{_descriptors} }),
		946
		947	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		948	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		949	0, sub { },
		950	);
		951	};
		952
		953	The callbacks are irrelevant (and are not even being called), the
		954	only purpose of those watchers is to wake up the process as soon as
		955	one of those events occurs (socket readable, or timer timed out). The
		956	corresponding EV::check watcher will then clean up:
		957
		958	our $snmp_check = EV::check sub {
		959	# destroy all watchers
		960	@snmp_watcher = ();
		961
		962	# make the dispatcher handle any new stuff
		963	... not shown
		964	};
		965
		966	The callbacks of the created watchers will not be called as the watchers
		967	are destroyed before this can happen (remember EV::check gets called
		968	first).
		969
		970	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		971
		972	=back
		973
		974
		975	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		976
		977	Fork watchers are called when a C<fork ()> was detected. The invocation
		978	is done before the event loop blocks next and before C<check> watchers
		979	are being called, and only in the child after the fork.
		980
		981	=over 4
		982
		983	=item $w = EV::fork $callback
		984
		985	=item $w = EV::fork_ns $callback
		986
		987	=item $w = $loop->fork ($callback)
		988
		989	=item $w = $loop->fork_ns ($callback)
		990
		991	Call the callback before the event loop is resumed in the child process
		992	after a fork.
		993
		994	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		995
		996	=back
		997
		998
		999	=head3 EMBED WATCHERS - when one backend isn't enough...
		1000
		1001	This is a rather advanced watcher type that lets you embed one event loop
		1002	into another (currently only IO events are supported in the embedded
		1003	loop, other types of watchers might be handled in a delayed or incorrect
		1004	fashion and must not be used).
		1005
		1006	See the libev documentation at
		1007	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		1008	(locally installed as F<EV::libev>) for more details.
		1009
		1010	In short, this watcher is most useful on BSD systems without working
		1011	kqueue to still be able to handle a large number of sockets:
		1012
		1013	my $socket_loop;
		1014
		1015	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		1016	if (
		1017	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		1018	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		1019	) {
		1020	# use kqueue for sockets
		1021	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		1022	}
		1023
		1024	# use the default loop otherwise
		1025	$socket_loop \|\|= EV::default_loop;
		1026
		1027	=over 4
		1028
		1029	=item $w = EV::embed $otherloop[, $callback]
		1030
		1031	=item $w = EV::embed_ns $otherloop[, $callback]
		1032
		1033	=item $w = $loop->embed ($otherloop[, $callback])
		1034
		1035	=item $w = $loop->embed_ns ($otherloop[, $callback])
		1036
		1037	Call the callback when the embedded event loop (C<$otherloop>) has any
		1038	I/O activity. The C<$callback> is optional: if it is missing, then the
		1039	embedded event loop will be managed automatically (which is recommended),
		1040	otherwise you have to invoke C<sweep> yourself.
		1041
		1042	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		1043
		1044	=back
		1045
		1046	=head3 ASYNC WATCHERS - how to wake up another event loop
		1047
		1048	Async watchers are provided by EV, but have little use in perl directly,
		1049	as perl neither supports threads running in parallel nor direct access to
		1050	signal handlers or other contexts where they could be of value.
		1051
		1052	It is, however, possible to use them from the XS level.
		1053
		1054	Please see the libev documentation for further details.
		1055
		1056	=over 4
		1057
		1058	=item $w = EV::async $callback
		1059
		1060	=item $w = EV::async_ns $callback
		1061
		1062	=item $w->send
		1063
		1064	=item $bool = $w->async_pending
		1065
		1066	=back
		1067
		1068
		1069	=head1 PERL SIGNALS
		1070
		1071	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1072	with EV is as the same as any other C library: Perl-signals will only be
		1073	handled when Perl runs, which means your signal handler might be invoked
		1074	only the next time an event callback is invoked.
		1075
		1076	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1077	ensure proper operations with regards to other event watchers.
		1078
		1079	If you cannot do this for whatever reason, you can also force a watcher
		1080	to be called on every event loop iteration by installing a C<EV::check>
		1081	watcher:
		1082
		1083	my $async_check = EV::check sub { };
		1084
		1085	This ensures that perl gets into control for a short time to handle any
		1086	pending signals, and also ensures (slightly) slower overall operation.
		1087
295	=head1 THREADS	1088	=head1 ITHREADS
296		1089
297	Threads are not supported by this in any way. Perl pseudo-threads is evil	1090	Ithreads are not supported by this module in any way. Perl pseudo-threads
298	and must die.	1091	is evil stuff and must die. Real threads as provided by Coro are fully
		1092	supported (and enhanced support is available via L<Coro::EV>).
299		1093
300	=head1 BUGS	1094	=head1 FORK
301		1095
302	Lots. Libevent itself isn't well tested and rather buggy, and this module	1096	Most of the "improved" event delivering mechanisms of modern operating
303	is quite new at the moment.	1097	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1098	not supported and usually destructive). Libev makes it possible to work
		1099	around this by having a function that recreates the kernel state after
		1100	fork in the child.
304		1101
305	Please note that the epoll method is not, in general, reliable in programs	1102	On non-win32 platforms, this module requires the pthread_atfork
306	that use fork (even if no libveent calls are being made in the forked	1103	functionality to do this automatically for you. This function is quite
307	process). If your program behaves erratically, try setting the environment	1104	buggy on most BSDs, though, so YMMV. The overhead for this is quite
308	variable C<EVENT_NOEPOLL> first when running the program.	1105	negligible, because everything the function currently does is set a flag
		1106	that is checked only when the event loop gets used the next time, so when
		1107	you do fork but not use EV, the overhead is minimal.
309		1108
310	In general, if you fork, then you can only use the EV module in one of the	1109	On win32, there is no notion of fork so all this doesn't apply, of course.
311	children.
312		1110
313	=cut	1111	=cut
314		1112
315	our $DIED = sub {	1113	our $DIED = sub {
316	warn "EV: error in callback (ignoring): $@";	1114	warn "EV: error in callback (ignoring): $@";
317	};	1115	};
318		1116
319	init;	1117	default_loop
320		1118	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
321	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
322		1119
323	1;	1120	1;
324		1121
325	=head1 SEE ALSO	1122	=head1 SEE ALSO
326		1123
327	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1124	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
328	L<EV::AnyEvent>.	1125	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1126	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1127	event-loop agnostic and portable event driven programming.
329		1128
330	=head1 AUTHOR	1129	=head1 AUTHOR
331		1130
332	Marc Lehmann <schmorp@schmorp.de>	1131	Marc Lehmann <schmorp@schmorp.de>
333	http://home.schmorp.de/	1132	http://home.schmorp.de/
334		1133
335	=cut	1134	=cut
336		1135

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Comparing EV/EV.pm (file contents): Revision 1.15 by root, Wed Oct 31 18:28:00 2007 UTC vs. Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.15 by root, Wed Oct 31 18:28:00 2007 UTC vs.
Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC