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

Comparing EV/EV.pm (file contents):
Revision 1.16 by root, Wed Oct 31 20:10:17 2007 UTC vs.
Revision 1.95 by root, Wed May 21 23:35:00 2008 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		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
22	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
23	};	23	};
24		24
25	# IO	25	# IO
26		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $revents) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($revents & EV::TIMEOUT) {
30	warn "nothing received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	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, $revents) = @_;
39	if ($revents & EV::TIMEOUT) {
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	};	30	};
47		31
48	# SIGNALS	32	# SIGNALS
49		33
50	my $w = EV::signal 'QUIT', sub {	34	my $w = EV::signal 'QUIT', sub {
51	warn "sigquit received\n";	35	warn "sigquit received\n";
52	};	36	};
53		37
54	my $w = EV::signal 3, sub {	38	# CHILD/PID STATUS CHANGES
55	warn "sigquit received (this is GNU/Linux, right?)\n";	39
		40	my $w = EV::child 666, 0, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
56	};	43	};
57		44
58	# CHILD/PID STATUS CHANGES	45	# STAT CHANGES
59		46	my $w = EV::stat "/etc/passwd", 10, sub {
60	my $w = EV::child 666, sub {
61	my ($w, $revents, $status) = @_;	47	my ($w, $revents) = @_;
		48	warn $w->path, " has changed somehow.\n";
62	};	49	};
63		50
64	# MAINLOOP	51	# MAINLOOP
65	EV::dispatch; # loop as long as watchers are active	52	EV::loop; # loop until EV::unloop is called or all watchers stop
66	EV::loop; # the same thing
67	EV::loop EV::LOOP_ONESHOT; # block until some events could be handles	53	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
68	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
69		55
70	=head1 DESCRIPTION	56	=head1 DESCRIPTION
71		57
72	This module provides an interface to libev	58	This module provides an interface to libev
73	(L<http://software.schmorp.de/pkg/libev.html>). You probably should	59	(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
74	acquaint yourself with its documentation and source code to be able to use	60	below is comprehensive, one might also consult the documentation of libev
75	this module fully.	61	itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
		62	subtle details on watcher semantics or some discussion on the available
		63	backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
		64	about in any case because it has much more detailed information.
		65
		66	This module is very fast and scalable. It is actually so fast that you
		67	can use it through the L<AnyEvent> module, stay portable to other event
		68	loops (if you don't rely on any watcher types not available through it)
		69	and still be faster than with any other event loop currently supported in
		70	Perl.
76		71
77	=cut	72	=cut
78		73
79	package EV;	74	package EV;
80		75
81	use strict;	76	use strict;
82		77
83	BEGIN {	78	BEGIN {
84	our $VERSION = '0.03';	79	our $VERSION = '3.41';
85	use XSLoader;	80	use XSLoader;
86	XSLoader::load "EV", $VERSION;	81	XSLoader::load "EV", $VERSION;
87	}	82	}
88		83
89	@EV::Io::ISA = "EV::Watcher";	84	@EV::IO::ISA =
90	@EV::Time::ISA = "EV::Watcher";
91	@EV::Timer::ISA = "EV::Time";	85	@EV::Timer::ISA =
92	@EV::Periodic::ISA = "EV::Time";	86	@EV::Periodic::ISA =
93	@EV::Signal::ISA = "EV::Watcher";	87	@EV::Signal::ISA =
94	@EV::Idle::ISA = "EV::Watcher";	88	@EV::Child::ISA =
95	@EV::Prepare::ISA = "EV::Watcher";	89	@EV::Stat::ISA =
96	@EV::Check::ISA = "EV::Watcher";	90	@EV::Idle::ISA =
		91	@EV::Prepare::ISA =
		92	@EV::Check::ISA =
		93	@EV::Embed::ISA =
		94	@EV::Fork::ISA =
		95	@EV::Async::ISA =
		96	"EV::Watcher";
		97
		98	@EV::Loop::Default::ISA = "EV::Loop";
		99
		100	=head1 EVENT LOOPS
		101
		102	EV supports multiple event loops: There is a single "default event loop"
		103	that can handle everything including signals and child watchers, and any
		104	number of "dynamic event loops" that can use different backends (with
		105	various limitations), but no child and signal watchers.
		106
		107	You do not have to do anything to create the default event loop: When
		108	the module is loaded a suitable backend is selected on the premise of
		109	selecting a working backend (which for example rules out kqueue on most
		110	BSDs). Modules should, unless they have "special needs" always use the
		111	default loop as this is fastest (perl-wise), best supported by other
		112	modules (e.g. AnyEvent or Coro) and most portable event loop.
		113
		114	For specific programs you can create additional event loops dynamically.
		115
		116	=over 4
		117
		118	=item $loop = new EV::loop [$flags]
		119
		120	Create a new event loop as per the specified flags. Please refer to the
		121	C<ev_loop_new ()> function description in the libev documentation
		122	(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
		123	for more info.
		124
		125	The loop will automatically be destroyed when it is no longer referenced
		126	by any watcher and the loop object goes out of scope.
		127
		128	Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
		129	is protected by this module.
		130
		131	=item $loop->loop_fork
		132
		133	Must be called after a fork in the child, before entering or continuing
		134	the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
		135	this fucntion automatically, at some performance loss (refer to the libev
		136	documentation).
		137
		138	=item $loop = EV::default_loop [$flags]
		139
		140	Return the default loop (which is a singleton object).
		141
		142	=back
		143
97		144
98	=head1 BASIC INTERFACE	145	=head1 BASIC INTERFACE
99		146
100	=over 4	147	=over 4
101		148
102	=item $EV::NPRI
103
104	How many priority levels are available.
105
106	=item $EV::DIED	149	=item $EV::DIED
107		150
108	Must contain a reference to a function that is called when a callback	151	Must contain a reference to a function that is called when a callback
109	throws an exception (with $@ containing thr error). The default prints an	152	throws an exception (with $@ containing the error). The default prints an
110	informative message and continues.	153	informative message and continues.
111		154
112	If this callback throws an exception it will be silently ignored.	155	If this callback throws an exception it will be silently ignored.
113		156
		157	=item $flags = EV::supported_backends
		158
		159	=item $flags = EV::recommended_backends
		160
		161	=item $flags = EV::embeddable_backends
		162
		163	Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
		164	instance of EV, the set of recommended backends (supposed to be good) for
		165	this platform and the set of embeddable backends (see EMBED WATCHERS).
		166
		167	=item EV::sleep $seconds
		168
		169	Block the process for the given number of (fractional) seconds.
		170
		171	=item $time = EV::time
		172
		173	Returns the current time in (fractional) seconds since the epoch.
		174
114	=item $time = EV::now	175	=item $time = EV::now
115		176
116	Returns the time in (fractional) seconds since the epoch.	177	=item $time = $loop->now
117		178
118	=item $version = EV::version	179	Returns the time the last event loop iteration has been started. This
		180	is the time that (relative) timers are based on, and refering to it is
		181	usually faster then calling EV::time.
119		182
120	=item $method = EV::method	183	=item $backend = EV::backend
121		184
122	Return version string and event polling method used.	185	=item $backend = $loop->backend
123		186
124	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	187	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		188	or EV::METHOD_EPOLL).
125		189
126	=item EV::loopexit $after	190	=item EV::loop [$flags]
127		191
128	Exit any active loop or dispatch after C<$after> seconds or immediately if	192	=item $loop->loop ([$flags])
129	C<$after> is missing or zero.
130		193
131	=item EV::dispatch	194	Begin checking for events and calling callbacks. It returns when a
		195	callback calls EV::unloop.
132		196
133	Same as C<EV::loop 0>.	197	The $flags argument can be one of the following:
134		198
135	=item EV::event $callback	199	0 as above
		200	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		201	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
136		202
137	Creates a new event watcher waiting for nothing, calling the given callback.	203	=item EV::unloop [$how]
138		204
		205	=item $loop->unloop ([$how])
		206
		207	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		208	innermost call to EV::loop return.
		209
		210	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		211	fast as possible.
		212
		213	=item $count = EV::loop_count
		214
		215	=item $count = $loop->loop_count
		216
		217	Return the number of times the event loop has polled for new
		218	events. Sometiems useful as a generation counter.
		219
		220	=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		221
		222	=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		223
		224	This function rolls together an I/O and a timer watcher for a single
		225	one-shot event without the need for managing a watcher object.
		226
		227	If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
		228	must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
		229	\| EV::WRITE>, indicating the type of I/O event you want to wait for. If
		230	you do not want to wait for some I/O event, specify C<undef> for
		231	C<$fh_or_undef> and C<0> for C<$events>).
		232
		233	If timeout is C<undef> or negative, then there will be no
		234	timeout. Otherwise a EV::timer with this value will be started.
		235
		236	When an error occurs or either the timeout or I/O watcher triggers, then
		237	the callback will be called with the received event set (in general
		238	you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
		239	C<EV::WRITE> and C<EV::TIMEOUT>).
		240
		241	EV::once doesn't return anything: the watchers stay active till either
		242	of them triggers, then they will be stopped and freed, and the callback
		243	invoked.
		244
		245	=item EV::feed_fd_event ($fd, $revents)
		246
		247	=item $loop->feed_fd_event ($fd, $revents)
		248
		249	Feed an event on a file descriptor into EV. EV will react to this call as
		250	if the readyness notifications specified by C<$revents> (a combination of
		251	C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
		252
		253	=item EV::feed_signal_event ($signal)
		254
		255	Feed a signal event into EV. EV will react to this call as if the signal
		256	specified by C<$signal> had occured.
		257
		258	=item EV::set_io_collect_interval $time
		259
		260	=item $loop->set_io_collect_interval ($time)
		261
		262	=item EV::set_timeout_collect_interval $time
		263
		264	=item $loop->set_timeout_collect_interval ($time)
		265
		266	These advanced functions set the minimum block interval when polling for I/O events and the minimum
		267	wait interval for timer events. See the libev documentation at
		268	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
		269	a more detailed discussion.
		270
		271	=back
		272
		273
		274	=head1 WATCHER OBJECTS
		275
		276	A watcher is an object that gets created to record your interest in some
		277	event. For instance, if you want to wait for STDIN to become readable, you
		278	would create an EV::io watcher for that:
		279
		280	my $watcher = EV::io *STDIN, EV::READ, sub {
		281	my ($watcher, $revents) = @_;
		282	warn "yeah, STDIN should now be readable without blocking!\n"
		283	};
		284
		285	All watchers can be active (waiting for events) or inactive (paused). Only
		286	active watchers will have their callbacks invoked. All callbacks will be
		287	called with at least two arguments: the watcher and a bitmask of received
		288	events.
		289
		290	Each watcher type has its associated bit in revents, so you can use the
		291	same callback for multiple watchers. The event mask is named after the
		292	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		293	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
		294	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		295	uses EV::TIMEOUT).
		296
		297	In the rare case where one wants to create a watcher but not start it at
		298	the same time, each constructor has a variant with a trailing C<_ns> in
		299	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		300
		301	Please note that a watcher will automatically be stopped when the watcher
		302	object is destroyed, so you I<need> to keep the watcher objects returned by
		303	the constructors.
		304
		305	Also, all methods changing some aspect of a watcher (->set, ->priority,
		306	->fh and so on) automatically stop and start it again if it is active,
		307	which means pending events get lost.
		308
		309	=head2 COMMON WATCHER METHODS
		310
		311	This section lists methods common to all watchers.
		312
		313	=over 4
		314
		315	=item $w->start
		316
		317	Starts a watcher if it isn't active already. Does nothing to an already
		318	active watcher. By default, all watchers start out in the active state
		319	(see the description of the C<_ns> variants if you need stopped watchers).
		320
		321	=item $w->stop
		322
		323	Stop a watcher if it is active. Also clear any pending events (events that
		324	have been received but that didn't yet result in a callback invocation),
		325	regardless of whether the watcher was active or not.
		326
		327	=item $bool = $w->is_active
		328
		329	Returns true if the watcher is active, false otherwise.
		330
		331	=item $current_data = $w->data
		332
		333	=item $old_data = $w->data ($new_data)
		334
		335	Queries a freely usable data scalar on the watcher and optionally changes
		336	it. This is a way to associate custom data with a watcher:
		337
		338	my $w = EV::timer 60, 0, sub {
		339	warn $_[0]->data;
		340	};
		341	$w->data ("print me!");
		342
		343	=item $current_cb = $w->cb
		344
		345	=item $old_cb = $w->cb ($new_cb)
		346
		347	Queries the callback on the watcher and optionally changes it. You can do
		348	this at any time without the watcher restarting.
		349
		350	=item $current_priority = $w->priority
		351
		352	=item $old_priority = $w->priority ($new_priority)
		353
		354	Queries the priority on the watcher and optionally changes it. Pending
		355	watchers with higher priority will be invoked first. The valid range of
		356	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		357	-2). If the priority is outside this range it will automatically be
		358	normalised to the nearest valid priority.
		359
		360	The default priority of any newly-created watcher is 0.
		361
		362	Note that the priority semantics have not yet been fleshed out and are
		363	subject to almost certain change.
		364
		365	=item $w->invoke ($revents)
		366
		367	Call the callback now with the given event mask.
		368
		369	=item $w->feed_event ($revents)
		370
		371	Feed some events on this watcher into EV. EV will react to this call as if
		372	the watcher had received the given C<$revents> mask.
		373
		374	=item $revents = $w->clear_pending
		375
		376	If the watcher is pending, this function clears its pending status and
		377	returns its C<$revents> bitset (as if its callback was invoked). If the
		378	watcher isn't pending it does nothing and returns C<0>.
		379
		380	=item $previous_state = $w->keepalive ($bool)
		381
		382	Normally, C<EV::loop> will return when there are no active watchers
		383	(which is a "deadlock" because no progress can be made anymore). This is
		384	convinient because it allows you to start your watchers (and your jobs),
		385	call C<EV::loop> once and when it returns you know that all your jobs are
		386	finished (or they forgot to register some watchers for their task :).
		387
		388	Sometimes, however, this gets in your way, for example when the module
		389	that calls C<EV::loop> (usually the main program) is not the same module
		390	as a long-living watcher (for example a DNS client module written by
		391	somebody else even). Then you might want any outstanding requests to be
		392	handled, but you would not want to keep C<EV::loop> from returning just
		393	because you happen to have this long-running UDP port watcher.
		394
		395	In this case you can clear the keepalive status, which means that even
		396	though your watcher is active, it won't keep C<EV::loop> from returning.
		397
		398	The initial value for keepalive is true (enabled), and you cna change it
		399	any time.
		400
		401	Example: Register an I/O watcher for some UDP socket but do not keep the
		402	event loop from running just because of that watcher.
		403
		404	my $udp_socket = ...
		405	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		406	$1000udp_watcher->keepalive (0);
		407
		408	=item $loop = $w->loop
		409
		410	Return the loop that this watcher is attached to.
		411
		412	=back
		413
		414
		415	=head1 WATCHER TYPES
		416
		417	Each of the following subsections describes a single watcher type.
		418
		419	=head3 I/O WATCHERS - is this file descriptor readable or writable?
		420
		421	=over 4
		422
139	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	423	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
140		424
141	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	425	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		426
		427	=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		428
		429	=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
142		430
143	As long as the returned watcher object is alive, call the C<$callback>	431	As long as the returned watcher object is alive, call the C<$callback>
144	when the events specified in C<$eventmask> happen. Initially, the timeout	432	when at least one of events specified in C<$eventmask> occurs.
145	is disabled.
146		433
147	You can additionall set a timeout to occur on the watcher, but note that
148	this timeout will not be reset when you get an I/O event in the EV::PERSIST
149	case, and reaching a timeout will always stop the watcher even in the
150	EV::PERSIST case.
151
152	If you want a timeout to occur only after a specific time of inactivity, set
153	a repeating timeout and do NOT use EV::PERSIST.
154
155	Eventmask can be one or more of these constants ORed together:	434	The $eventmask can be one or more of these constants ORed together:
156		435
157	EV::READ wait until read() wouldn't block anymore	436	EV::READ wait until read() wouldn't block anymore
158	EV::WRITE wait until write() wouldn't block anymore	437	EV::WRITE wait until write() wouldn't block anymore
159	EV::PERSIST stay active after a (non-timeout) event occured
160		438
161	The C<io_ns> variant doesn't add/start the newly created watcher.	439	The C<io_ns> variant doesn't start (activate) the newly created watcher.
162		440
163	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	441	=item $w->set ($fileno_or_fh, $eventmask)
164		442
165	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	443	Reconfigures the watcher, see the constructor above for details. Can be
		444	called at any time.
166		445
167	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	446	=item $current_fh = $w->fh
168	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
169	and will automatically be cleared. The watcher will be restarted after each event.
170		447
171	If the timeout is zero or undef, no timeout will be set, and a normal	448	=item $old_fh = $w->fh ($new_fh)
172	watcher (with the persist flag set!) will be created.
173		449
174	This has the effect of timing out after the specified period of inactivity	450	Returns the previously set filehandle and optionally set a new one.
175	has happened.
176		451
177	Due to the design of libevent, this is also relatively inefficient, having	452	=item $current_eventmask = $w->events
178	one or two io watchers and a separate timeout watcher that you reset on
179	activity (by calling its C<start> method) is usually more efficient.
180		453
		454	=item $old_eventmask = $w->events ($new_eventmask)
		455
		456	Returns the previously set event mask and optionally set a new one.
		457
		458	=back
		459
		460
		461	=head3 TIMER WATCHERS - relative and optionally repeating timeouts
		462
		463	=over 4
		464
181	=item my $w = EV::timer $after, $repeat, $callback	465	=item $w = EV::timer $after, $repeat, $callback
182		466
183	=item my $w = EV::timer_ns $after, $repeat, $callback	467	=item $w = EV::timer_ns $after, $repeat, $callback
184		468
185	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	469	=item $w = $loop->timer ($after, $repeat, $callback)
186	timer will be restarted after the callback returns. This means that the
187	callback would be called roughly every C<$after> seconds, prolonged by the
188	time the callback takes.
189		470
		471	=item $w = $loop->timer_ns ($after, $repeat, $callback)
		472
		473	Calls the callback after C<$after> seconds (which may be fractional). If
		474	C<$repeat> is non-zero, the timer will be restarted (with the $repeat
		475	value as $after) after the callback returns.
		476
		477	This means that the callback would be called roughly after C<$after>
		478	seconds, and then every C<$repeat> seconds. The timer does his best not
		479	to drift, but it will not invoke the timer more often then once per event
		480	loop iteration, and might drift in other cases. If that isn't acceptable,
		481	look at EV::periodic, which can provide long-term stable timers.
		482
		483	The timer is based on a monotonic clock, that is, if somebody is sitting
		484	in front of the machine while the timer is running and changes the system
		485	clock, the timer will nevertheless run (roughly) the same time.
		486
190	The C<timer_ns> variant doesn't add/start the newly created watcher.	487	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
191		488
192	=item my $w = EV::timer_abs $at, $interval, $callback	489	=item $w->set ($after, $repeat)
193		490
194	=item my $w = EV::timer_abs_ns $at, $interval, $callback	491	Reconfigures the watcher, see the constructor above for details. Can be called at
		492	any time.
195		493
196	Similar to EV::timer, but the time is given as an absolute point in time	494	=item $w->again
197	(C<$at>), plus an optional C<$interval>.
198		495
199	If the C<$interval> is zero, then the callback will be called at the time	496	Similar to the C<start> method, but has special semantics for repeating timers:
200	C<$at> if that is in the future, or as soon as possible if its in the
201	past. It will not automatically repeat.
202		497
203	If the C<$interval> is nonzero, then the watcher will always be scheduled	498	If the timer is active and non-repeating, it will be stopped.
204	to time out at the next C<$at + integer * $interval> time.
205		499
206	This can be used to schedule a callback to run at very regular intervals,	500	If the timer is active and repeating, reset the timeout to occur
207	as long as the processing time is less then the interval (otherwise	501	C<$repeat> seconds after now.
208	obviously events will be skipped).	502
		503	If the timer is inactive and repeating, start it using the repeat value.
		504
		505	Otherwise do nothing.
		506
		507	This behaviour is useful when you have a timeout for some IO
		508	operation. You create a timer object with the same value for C<$after> and
		509	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		510	on the timeout.
		511
		512	=back
		513
		514
		515	=head3 PERIODIC WATCHERS - to cron or not to cron?
		516
		517	=over 4
		518
		519	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		520
		521	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		522
		523	=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		524
		525	=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
		526
		527	Similar to EV::timer, but is not based on relative timeouts but on
		528	absolute times. Apart from creating "simple" timers that trigger "at" the
		529	specified time, it can also be used for non-drifting absolute timers and
		530	more complex, cron-like, setups that are not adversely affected by time
		531	jumps (i.e. when the system clock is changed by explicit date -s or other
		532	means such as ntpd). It is also the most complex watcher type in EV.
		533
		534	It has three distinct "modes":
		535
		536	=over 4
		537
		538	=item * absolute timer ($interval = $reschedule_cb = 0)
		539
		540	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		541	will not adjust when a time jump occurs, that is, if it is to be run
		542	at January 1st 2011 then it will run when the system time reaches or
		543	surpasses this time.
		544
		545	=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
		546
		547	In this mode the watcher will always be scheduled to time out at the
		548	next C<$at + N * $interval> time (for some integer N) and then repeat,
		549	regardless of any time jumps.
		550
		551	This can be used to create timers that do not drift with respect to system
		552	time:
		553
		554	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		555
		556	That doesn't mean there will always be 3600 seconds in between triggers,
		557	but only that the the clalback will be called when the system time shows a
		558	full hour (UTC).
209		559
210	Another way to think about it (for the mathematically inclined) is that	560	Another way to think about it (for the mathematically inclined) is that
211	C<timer_abs> will try to tun the callback at the next possible time where	561	EV::periodic will try to run the callback in this mode at the next
212	C<$time = $at (mod $interval)>, regardless of any time jumps.	562	possible time where C<$time = $at (mod $interval)>, regardless of any time
		563	jumps.
213		564
		565	=item * manual reschedule mode ($reschedule_cb = coderef)
		566
		567	In this mode $interval and $at are both being ignored. Instead, each
		568	time the periodic watcher gets scheduled, the reschedule callback
		569	($reschedule_cb) will be called with the watcher as first, and the current
		570	time as second argument.
		571
		572	I<This callback MUST NOT stop or destroy this or any other periodic
		573	watcher, ever, and MUST NOT call any event loop functions or methods>. If
		574	you need to stop it, return 1e30 and stop it afterwards. You may create
		575	and start a C<EV::prepare> watcher for this task.
		576
		577	It must return the next time to trigger, based on the passed time value
		578	(that is, the lowest time value larger than or equal to to the second
		579	argument). It will usually be called just before the callback will be
		580	triggered, but might be called at other times, too.
		581
		582	This can be used to create very complex timers, such as a timer that
		583	triggers on each midnight, local time (actually 24 hours after the last
		584	midnight, to keep the example simple. If you know a way to do it correctly
		585	in about the same space (without requiring elaborate modules), drop me a
		586	note :):
		587
		588	my $daily = EV::periodic 0, 0, sub {
		589	my ($w, $now) = @_;
		590
		591	use Time::Local ();
		592	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		593	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		594	}, sub {
		595	print "it's midnight or likely shortly after, now\n";
		596	};
		597
		598	=back
		599
214	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	600	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
215		601
		602	=item $w->set ($at, $interval, $reschedule_cb)
		603
		604	Reconfigures the watcher, see the constructor above for details. Can be called at
		605	any time.
		606
		607	=item $w->again
		608
		609	Simply stops and starts the watcher again.
		610
		611	=item $time = $w->at
		612
		613	Return the time that the watcher is expected to trigger next.
		614
		615	=back
		616
		617
		618	=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
		619
		620	=over 4
		621
216	=item my $w = EV::signal $signal, $callback	622	=item $w = EV::signal $signal, $callback
217		623
218	=item my $w = EV::signal_ns $signal, $callback	624	=item $w = EV::signal_ns $signal, $callback
219		625
220	Call the callback when $signal is received (the signal can be specified	626	Call the callback when $signal is received (the signal can be specified by
221	by number or by name, just as with kill or %SIG). Signal watchers are	627	number or by name, just as with C<kill> or C<%SIG>).
222	persistent no natter what.
223		628
224	EV will grab the signal for the process (the kernel only allows one	629	EV will grab the signal for the process (the kernel only allows one
225	component to receive signals) when you start a signal watcher, and	630	component to receive a signal at a time) when you start a signal watcher,
226	removes it again when you stop it. Pelr does the same when you add/remove	631	and removes it again when you stop it. Perl does the same when you
227	callbacks to %SIG, so watch out.	632	add/remove callbacks to C<%SIG>, so watch out.
228		633
229	Unfortunately, only one handler can be registered per signal. Screw	634	You can have as many signal watchers per signal as you want.
230	libevent.
231		635
232	The C<signal_ns> variant doesn't add/start the newly created watcher.	636	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
233		637
234	=back	638	=item $w->set ($signal)
235		639
236	=head1 THE EV::Event CLASS	640	Reconfigures the watcher, see the constructor above for details. Can be
		641	called at any time.
237		642
238	All EV functions creating an event watcher (designated by C<my $w =>
239	above) support the following methods on the returned watcher object:
240
241	=over 4
242
243	=item $w->add ($timeout)
244
245	Stops and (re-)starts the event watcher, setting the optional timeout to
246	the given value, or clearing the timeout if none is given.
247
248	=item $w->start
249
250	Stops and (re-)starts the event watcher without touching the timeout.
251
252	=item $w->del
253
254	=item $w->stop
255
256	Stop the event watcher if it was started.
257
258	=item $current_callback = $w->cb
259
260	=item $old_callback = $w->cb ($new_callback)
261
262	Return the previously set callback and optionally set a new one.
263
264	=item $current_fh = $w->fh
265
266	=item $old_fh = $w->fh ($new_fh)
267
268	Returns the previously set filehandle and optionally set a new one (also
269	clears the EV::SIGNAL flag when setting a filehandle).
270
271	=item $current_signal = $w->signal	643	=item $current_signum = $w->signal
272		644
273	=item $old_signal = $w->signal ($new_signal)	645	=item $old_signum = $w->signal ($new_signal)
274		646
		647	Returns the previously set signal (always as a number not name) and
		648	optionally set a new one.
		649
		650	=back
		651
		652
		653	=head3 CHILD WATCHERS - watch out for process status changes
		654
		655	=over 4
		656
		657	=item $w = EV::child $pid, $trace, $callback
		658
		659	=item $w = EV::child_ns $pid, $trace, $callback
		660
		661	=item $w = $loop->child ($pid, $trace, $callback)
		662
		663	=item $w = $loop->child_ns ($pid, $trace, $callback)
		664
		665	Call the callback when a status change for pid C<$pid> (or any pid
		666	if C<$pid> is 0) has been received (a status change happens when the
		667	process terminates or is killed, or, when trace is true, additionally when
		668	it is stopped or continued). More precisely: when the process receives
		669	a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
		670	changed/zombie children and call the callback.
		671
		672	It is valid (and fully supported) to install a child watcher after a child
		673	has exited but before the event loop has started its next iteration (for
		674	example, first you C<fork>, then the new child process might exit, and
		675	only then do you install a child watcher in the parent for the new pid).
		676
		677	You can access both exit (or tracing) status and pid by using the
		678	C<rstatus> and C<rpid> methods on the watcher object.
		679
		680	You can have as many pid watchers per pid as you want, they will all be
		681	called.
		682
		683	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		684
		685	=item $w->set ($pid, $trace)
		686
		687	Reconfigures the watcher, see the constructor above for details. Can be called at
		688	any time.
		689
		690	=item $current_pid = $w->pid
		691
275	Returns the previously set signal number and optionally set a new one (also sets	692	Returns the previously set process id and optionally set a new one.
276	the EV::SIGNAL flag when setting a signal).
277		693
278	=item $current_eventmask = $w->events	694	=item $exit_status = $w->rstatus
279		695
280	=item $old_eventmask = $w->events ($new_eventmask)	696	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		697	in perlfunc).
281		698
		699	=item $pid = $w->rpid
		700
		701	Return the pid of the awaited child (useful when you have installed a
		702	watcher for all pids).
		703
		704	=back
		705
		706
		707	=head3 STAT WATCHERS - did the file attributes just change?
		708
		709	=over 4
		710
		711	=item $w = EV::stat $path, $interval, $callback
		712
		713	=item $w = EV::stat_ns $path, $interval, $callback
		714
		715	=item $w = $loop->stat ($path, $interval, $callback)
		716
		717	=item $w = $loop->stat_ns ($path, $interval, $callback)
		718
		719	Call the callback when a file status change has been detected on
		720	C<$path>. The C<$path> does not need to exist, changing from "path exists"
		721	to "path does not exist" is a status change like any other.
		722
		723	The C<$interval> is a recommended polling interval for systems where
		724	OS-supported change notifications don't exist or are not supported. If
		725	you use C<0> then an unspecified default is used (which is highly
		726	recommended!), which is to be expected to be around five seconds usually.
		727
		728	This watcher type is not meant for massive numbers of stat watchers,
		729	as even with OS-supported change notifications, this can be
		730	resource-intensive.
		731
		732	The C<stat_ns> variant doesn't start (activate) the newly created watcher.
		733
		734	=item ... = $w->stat
		735
		736	This call is very similar to the perl C<stat> built-in: It stats (using
		737	C<lstat>) the path specified in the watcher and sets perls stat cache (as
		738	well as EV's idea of the current stat values) to the values found.
		739
		740	In scalar context, a boolean is return indicating success or failure of
		741	the stat. In list context, the same 13-value list as with stat is returned
		742	(except that the blksize and blocks fields are not reliable).
		743
		744	In the case of an error, errno is set to C<ENOENT> (regardless of the
		745	actual error value) and the C<nlink> value is forced to zero (if the stat
		746	was successful then nlink is guaranteed to be non-zero).
		747
		748	See also the next two entries for more info.
		749
		750	=item ... = $w->attr
		751
		752	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		753	the values most recently detected by EV. See the next entry for more info.
		754
		755	=item ... = $w->prev
		756
		757	Just like C<< $w->stat >>, but without the initial stat'ing: this returns
		758	the previous set of values, before the change.
		759
		760	That is, when the watcher callback is invoked, C<< $w->prev >> will be set
		761	to the values found I<before> a change was detected, while C<< $w->attr >>
		762	returns the values found leading to the change detection. The difference (if any)
		763	between C<prev> and C<attr> is what triggered the callback.
		764
		765	If you did something to the filesystem object and do not want to trigger
		766	yet another change, you can call C<stat> to update EV's idea of what the
		767	current attributes are.
		768
		769	=item $w->set ($path, $interval)
		770
		771	Reconfigures the watcher, see the constructor above for details. Can be
		772	called at any time.
		773
		774	=item $current_path = $w->path
		775
		776	=item $old_path = $w->path ($new_path)
		777
282	Returns the previously set event mask and optionally set a new one.	778	Returns the previously set path and optionally set a new one.
283		779
284	=item $w->timeout ($after, $repeat)	780	=item $current_interval = $w->interval
285		781
286	Resets the timeout (see C<EV::timer> for details).	782	=item $old_interval = $w->interval ($new_interval)
287		783
288	=item $w->timeout_abs ($at, $interval)	784	Returns the previously set interval and optionally set a new one. Can be
		785	used to query the actual interval used.
289		786
290	Resets the timeout (see C<EV::timer_abs> for details).
291
292	=item $w->priority_set ($priority)
293
294	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
295
296	=back	787	=back
		788
		789
		790	=head3 IDLE WATCHERS - when you've got nothing better to do...
		791
		792	=over 4
		793
		794	=item $w = EV::idle $callback
		795
		796	=item $w = EV::idle_ns $callback
		797
		798	=item $w = $loop->idle ($callback)
		799
		800	=item $w = $loop->idle_ns ($callback)
		801
		802	Call the callback when there are no other pending watchers of the same or
		803	higher priority (excluding check, prepare and other idle watchers of the
		804	same or lower priority, of course). They are called idle watchers because
		805	when the watcher is the highest priority pending event in the process, the
		806	process is considered to be idle at that priority.
		807
		808	If you want a watcher that is only ever called when I<no> other events are
		809	outstanding you have to set the priority to C<EV::MINPRI>.
		810
		811	The process will not block as long as any idle watchers are active, and
		812	they will be called repeatedly until stopped.
		813
		814	For example, if you have idle watchers at priority C<0> and C<1>, and
		815	an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
		816	and the I/O watcher will always run when ready. Only when the idle watcher
		817	at priority C<1> is stopped and the I/O watcher at priority C<0> is not
		818	pending with the C<0>-priority idle watcher be invoked.
		819
		820	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		821
		822	=back
		823
		824
		825	=head3 PREPARE WATCHERS - customise your event loop!
		826
		827	=over 4
		828
		829	=item $w = EV::prepare $callback
		830
		831	=item $w = EV::prepare_ns $callback
		832
		833	=item $w = $loop->prepare ($callback)
		834
		835	=item $w = $loop->prepare_ns ($callback)
		836
		837	Call the callback just before the process would block. You can still
		838	create/modify any watchers at this point.
		839
		840	See the EV::check watcher, below, for explanations and an example.
		841
		842	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		843
		844	=back
		845
		846
		847	=head3 CHECK WATCHERS - customise your event loop even more!
		848
		849	=over 4
		850
		851	=item $w = EV::check $callback
		852
		853	=item $w = EV::check_ns $callback
		854
		855	=item $w = $loop->check ($callback)
		856
		857	=item $w = $loop->check_ns ($callback)
		858
		859	Call the callback just after the process wakes up again (after it has
		860	gathered events), but before any other callbacks have been invoked.
		861
		862	This is used to integrate other event-based software into the EV
		863	mainloop: You register a prepare callback and in there, you create io and
		864	timer watchers as required by the other software. Here is a real-world
		865	example of integrating Net::SNMP (with some details left out):
		866
		867	our @snmp_watcher;
		868
		869	our $snmp_prepare = EV::prepare sub {
		870	# do nothing unless active
		871	$dispatcher->{_event_queue_h}
		872	or return;
		873
		874	# make the dispatcher handle any outstanding stuff
		875	... not shown
		876
		877	# create an I/O watcher for each and every socket
		878	@snmp_watcher = (
		879	(map { EV::io $_, EV::READ, sub { } }
		880	keys %{ $dispatcher->{_descriptors} }),
		881
		882	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		883	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		884	0, sub { },
		885	);
		886	};
		887
		888	The callbacks are irrelevant (and are not even being called), the
		889	only purpose of those watchers is to wake up the process as soon as
		890	one of those events occurs (socket readable, or timer timed out). The
		891	corresponding EV::check watcher will then clean up:
		892
		893	our $snmp_check = EV::check sub {
		894	# destroy all watchers
		895	@snmp_watcher = ();
		896
		897	# make the dispatcher handle any new stuff
		898	... not shown
		899	};
		900
		901	The callbacks of the created watchers will not be called as the watchers
		902	are destroyed before this cna happen (remember EV::check gets called
		903	first).
		904
		905	The C<check_ns> variant doesn't start (activate) the newly created watcher.
		906
		907	=back
		908
		909
		910	=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
		911
		912	Fork watchers are called when a C<fork ()> was detected. The invocation
		913	is done before the event loop blocks next and before C<check> watchers
		914	are being called, and only in the child after the fork.
		915
		916	=over 4
		917
		918	=item $w = EV::fork $callback
		919
		920	=item $w = EV::fork_ns $callback
		921
		922	=item $w = $loop->fork ($callback)
		923
		924	=item $w = $loop->fork_ns ($callback)
		925
		926	Call the callback before the event loop is resumed in the child process
		927	after a fork.
		928
		929	The C<fork_ns> variant doesn't start (activate) the newly created watcher.
		930
		931	=back
		932
		933
		934	=head3 EMBED WATCHERS - when one backend isn't enough...
		935
		936	This is a rather advanced watcher type that lets you embed one event loop
		937	into another (currently only IO events are supported in the embedded
		938	loop, other types of watchers might be handled in a delayed or incorrect
		939	fashion and must not be used).
		940
		941	See the libev documentation at
		942	L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
		943	for more details.
		944
		945	In short, this watcher is most useful on BSD systems without working
		946	kqueue to still be able to handle a large number of sockets:
		947
		948	my $socket_loop;
		949
		950	# check wether we use SELECT or POLL _and_ KQUEUE is supported
		951	if (
		952	(EV::backend & (EV::BACKEND_POLL \| EV::BACKEND_SELECT))
		953	&& (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
		954	) {
		955	# use kqueue for sockets
		956	$socket_loop = new EV::Loop EV::BACKEND_KQUEUE \| EV::FLAG_NOENV;
		957	}
		958
		959	# use the default loop otherwise
		960	$socket_loop \|\|= EV::default_loop;
		961
		962	=over 4
		963
		964	=item $w = EV::embed $otherloop, $callback
		965
		966	=item $w = EV::embed_ns $otherloop, $callback
		967
		968	=item $w = $loop->embed ($otherloop, $callback)
		969
		970	=item $w = $loop->embed_ns ($otherloop, $callback)
		971
		972	Call the callback when the embedded event loop (C<$otherloop>) has any
		973	I/O activity. The C<$callback> should alwas be specified as C<undef> in
		974	this version of EV, which means the embedded event loop will be managed
		975	automatically.
		976
		977	The C<embed_ns> variant doesn't start (activate) the newly created watcher.
		978
		979	=back
		980
		981	=head3 ASYNC WATCHERS - how to wake up another event loop
		982
		983	Async watchers are provided by EV, but have little use in perl directly, as perl
		984	neither supports threads nor direct access to signal handlers or other
		985	contexts where they could be of value.
		986
		987	It is, however, possible to use them from the XS level.
		988
		989	Please see the libev documentation for further details.
		990
		991	=over 4
		992
		993	=item $w = EV::async $callback
		994
		995	=item $w = EV::async_ns $callback
		996
		997	=item $w->send
		998
		999	=item $bool = $w->async_pending
		1000
		1001	=back
		1002
		1003
		1004	=head1 PERL SIGNALS
		1005
		1006	While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
		1007	with EV is as the same as any other C library: Perl-signals will only be
		1008	handled when Perl runs, which means your signal handler might be invoked
		1009	only the next time an event callback is invoked.
		1010
		1011	The solution is to use EV signal watchers (see C<EV::signal>), which will
		1012	ensure proper operations with regards to other event watchers.
		1013
		1014	If you cannot do this for whatever reason, you can also force a watcher
		1015	to be called on every event loop iteration by installing a C<EV::check>
		1016	watcher:
		1017
		1018	my $async_check = EV::check sub { };
		1019
		1020	This ensures that perl gets into control for a short time to handle any
		1021	pending signals, and also ensures (slightly) slower overall operation.
297		1022
298	=head1 THREADS	1023	=head1 THREADS
299		1024
300	Threads are not supported by this in any way. Perl pseudo-threads is evil	1025	Threads are not supported by this module in any way. Perl pseudo-threads
301	and must die.	1026	is evil stuff and must die. As soon as Perl gains real threads I will work
		1027	on thread support for it.
302		1028
303	=head1 BUGS	1029	=head1 FORK
304		1030
305	Lots. Libevent itself isn't well tested and rather buggy, and this module	1031	Most of the "improved" event delivering mechanisms of modern operating
306	is quite new at the moment.	1032	systems have quite a few problems with fork(2) (to put it bluntly: it is
		1033	not supported and usually destructive). Libev makes it possible to work
		1034	around this by having a function that recreates the kernel state after
		1035	fork in the child.
307		1036
308	Please note that the epoll method is not, in general, reliable in programs	1037	On non-win32 platforms, this module requires the pthread_atfork
309	that use fork (even if no libveent calls are being made in the forked	1038	functionality to do this automatically for you. This function is quite
310	process). If your program behaves erratically, try setting the environment	1039	buggy on most BSDs, though, so YMMV. The overhead for this is quite
311	variable C<EVENT_NOEPOLL> first when running the program.	1040	negligible, because everything the function currently does is set a flag
		1041	that is checked only when the event loop gets used the next time, so when
		1042	you do fork but not use EV, the overhead is minimal.
312		1043
313	In general, if you fork, then you can only use the EV module in one of the	1044	On win32, there is no notion of fork so all this doesn't apply, of course.
314	children.
315		1045
316	=cut	1046	=cut
317		1047
318	our $DIED = sub {	1048	our $DIED = sub {
319	warn "EV: error in callback (ignoring): $@";	1049	warn "EV: error in callback (ignoring): $@";
320	};	1050	};
321		1051
322	init;	1052	default_loop
323		1053	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
324	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
325		1054
326	1;	1055	1;
327		1056
328	=head1 SEE ALSO	1057	=head1 SEE ALSO
329		1058
330	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	1059	L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
331	L<EV::AnyEvent>.	1060	event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
		1061	coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
		1062	event-loop agnostic and portable event driven programming.
332		1063
333	=head1 AUTHOR	1064	=head1 AUTHOR
334		1065
335	Marc Lehmann <schmorp@schmorp.de>	1066	Marc Lehmann <schmorp@schmorp.de>
336	http://home.schmorp.de/	1067	http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.16 by root, Wed Oct 31 20:10:17 2007 UTC vs. Revision 1.95 by root, Wed May 21 23:35:00 2008 UTC

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Comparing EV/EV.pm (file contents):
Revision 1.16 by root, Wed Oct 31 20:10:17 2007 UTC vs.
Revision 1.95 by root, Wed May 21 23:35:00 2008 UTC