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

Comparing Coro/Coro.pm (file contents):
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs.
Revision 1.253 by root, Fri May 29 07:01:18 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only real threads in perl
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
11	print "2\n";	11	print "2\n";
12	cede; # yield back to main	12	cede; # yield back to main
13	print "4\n";	13	print "4\n";
14	};	14	};
15	print "1\n";	15	print "1\n";
16	cede; # yield to coroutine	16	cede; # yield to coro
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
21	use Coro::Semaphore;	21	use Coro::Semaphore;
…		…
26	$locked = 1;	26	$locked = 1;
27	$lock->up;	27	$lock->up;
28		28
29	=head1 DESCRIPTION	29	=head1 DESCRIPTION
30		30
31	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
32	threads but don't (in general) run in parallel at the same time even	32	manpage. This manpage mainly contains reference information.
33	on SMP machines. The specific flavor of coroutine used in this module
34	also guarantees you that it will not switch between coroutines unless
35	necessary, at easily-identified points in your program, so locking and
36	parallel access are rarely an issue, making coroutine programming much
37	safer and easier than threads programming.
38		33
39	Unlike a normal perl program, however, coroutines allow you to have	34	This module collection manages continuations in general, most often in
40	multiple running interpreters that share data, which is especially useful	35	the form of cooperative threads (also called coros, or simply "coro"
41	to code pseudo-parallel processes and for event-based programming, such as	36	in the documentation). They are similar to kernel threads but don't (in
42	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to	37	general) run in parallel at the same time even on SMP machines. The
43	learn more.	38	specific flavor of thread offered by this module also guarantees you that
		39	it will not switch between threads unless necessary, at easily-identified
		40	points in your program, so locking and parallel access are rarely an
		41	issue, making thread programming much safer and easier than using other
		42	thread models.
44		43
45	Coroutines are also useful because Perl has no support for threads (the so	44	Unlike the so-called "Perl threads" (which are not actually real threads
46	called "threads" that perl offers are nothing more than the (bad) process	45	but only the windows process emulation ported to unix, and as such act
47	emulation coming from the Windows platform: On standard operating systems	46	as processes), Coro provides a full shared address space, which makes
48	they serve no purpose whatsoever, except by making your programs slow and	47	communication between threads very easy. And Coro's threads are fast,
49	making them use a lot of memory. Best disable them when building perl, or	48	too: disabling the Windows process emulation code in your perl and using
50	aks your software vendor/distributor to do it for you).	49	Coro can easily result in a two to four times speed increase for your
		50	programs. A parallel matrix multiplication benchmark runs over 300 times
		51	faster on a single core than perl's pseudo-threads on a quad core using
		52	all four cores.
51		53
		54	Coro achieves that by supporting multiple running interpreters that share
		55	data, which is especially useful to code pseudo-parallel processes and
		56	for event-based programming, such as multiple HTTP-GET requests running
		57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		58	into an event-based environment.
		59
52	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
54	its own set of lexicals and its own set of perls most important global	62	its own set of lexicals and its own set of perls most important global
55	variables (see L<Coro::State> for more configuration).	63	variables (see L<Coro::State> for more configuration and background info).
		64
		65	See also the C<SEE ALSO> section at the end of this document - the Coro
		66	module family is quite large.
56		67
57	=cut	68	=cut
58		69
59	package Coro;	70	package Coro;
60		71
61	use strict;	72	use strict qw(vars subs);
62	no warnings "uninitialized";	73	no warnings "uninitialized";
63		74
		75	use Guard ();
		76
64	use Coro::State;	77	use Coro::State;
65		78
66	use base qw(Coro::State Exporter);	79	use base qw(Coro::State Exporter);
67		80
68	our $idle; # idle handler	81	our $idle; # idle handler
69	our $main; # main coroutine	82	our $main; # main coro
70	our $current; # current coroutine	83	our $current; # current coro
71		84
72	our $VERSION = 4.8;	85	our $VERSION = 5.132;
73		86
74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
75	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
77	);	90	);
78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
79		92
		93	=head1 GLOBAL VARIABLES
		94
80	=over 4	95	=over 4
81		96
82	=item $Coro::main	97	=item $Coro::main
83		98
84	This variable stores the coroutine object that represents the main	99	This variable stores the Coro object that represents the main
85	program. While you cna C<ready> it and do most other things you can do to	100	program. While you cna C<ready> it and do most other things you can do to
86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	101	coro, it is mainly useful to compare again C<$Coro::current>, to see
87	whether you are running in the main program or not.	102	whether you are running in the main program or not.
88		103
89	=cut	104	=cut
90		105
91	$main = new Coro;	106	# $main is now being initialised by Coro::State
92		107
93	=item $Coro::current	108	=item $Coro::current
94		109
95	The coroutine object representing the current coroutine (the last	110	The Coro object representing the current coro (the last
96	coroutine that the Coro scheduler switched to). The initial value is	111	coro that the Coro scheduler switched to). The initial value is
97	C<$main> (of course).	112	C<$Coro::main> (of course).
98		113
99	This variable is B<strictly> I<read-only>. You can take copies of the	114	This variable is B<strictly> I<read-only>. You can take copies of the
100	value stored in it and use it as any other coroutine object, but you must	115	value stored in it and use it as any other Coro object, but you must
101	not otherwise modify the variable itself.	116	not otherwise modify the variable itself.
102		117
103	=cut	118	=cut
104		119
105	$main->{desc} = "[main::]";
106
107	# maybe some other module used Coro::Specific before...
108	$main->{_specific} = $current->{_specific}
109	if $current;
110
111	_set_current $main;
112
113	sub current() { $current } # [DEPRECATED]	120	sub current() { $current } # [DEPRECATED]
114		121
115	=item $Coro::idle	122	=item $Coro::idle
116		123
117	This variable is mainly useful to integrate Coro into event loops. It is	124	This variable is mainly useful to integrate Coro into event loops. It is
118	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is	125	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
119	pretty low-level functionality.	126	pretty low-level functionality.
120		127
121	This variable stores a callback that is called whenever the scheduler	128	This variable stores either a Coro object or a callback.
		129
		130	If it is a callback, the it is called whenever the scheduler finds no
122	finds no ready coroutines to run. The default implementation prints	131	ready coros to run. The default implementation prints "FATAL:
123	"FATAL: deadlock detected" and exits, because the program has no other way	132	deadlock detected" and exits, because the program has no other way to
124	to continue.	133	continue.
125		134
		135	If it is a coro object, then this object will be readied (without
		136	invoking any ready hooks, however) when the scheduler finds no other ready
		137	coros to run.
		138
126	This hook is overwritten by modules such as C<Coro::Timer> and	139	This hook is overwritten by modules such as C<Coro::EV> and
127	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	140	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
128	coroutine so the scheduler can run it.	141	coro so the scheduler can run it.
129		142
130	Note that the callback I<must not>, under any circumstances, block	143	Note that the callback I<must not>, under any circumstances, block
131	the current coroutine. Normally, this is achieved by having an "idle	144	the current coro. Normally, this is achieved by having an "idle
132	coroutine" that calls the event loop and then blocks again, and then	145	coro" that calls the event loop and then blocks again, and then
133	readying that coroutine in the idle handler.	146	readying that coro in the idle handler, or by simply placing the idle
		147	coro in this variable.
134		148
135	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	149	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
136	technique.	150	technique.
137		151
138	Please note that if your callback recursively invokes perl (e.g. for event	152	Please note that if your callback recursively invokes perl (e.g. for event
…		…
143	$idle = sub {	157	$idle = sub {
144	require Carp;	158	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	159	Carp::croak ("FATAL: deadlock detected");
146	};	160	};
147		161
148	sub _cancel {
149	my ($self) = @_;
150
151	# free coroutine data and mark as destructed
152	$self->_destroy
153	or return;
154
155	# call all destruction callbacks
156	$_->(@{$self->{_status}})
157	for @{(delete $self->{_on_destroy}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
161	# cannot destroy itself.	163	# cannot destroy itself.
162	my @destroy;	164	our @destroy;
163	my $manager;	165	our $manager;
164		166
165	$manager = new Coro sub {	167	$manager = new Coro sub {
166	while () {	168	while () {
167	(shift @destroy)->_cancel	169	Coro::State::cancel shift @destroy
168	while @destroy;	170	while @destroy;
169		171
170	&schedule;	172	&schedule;
171	}	173	}
172	};	174	};
173	$manager->desc ("[coro manager]");	175	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	176	$manager->prio (PRIO_MAX);
175		177
176	=back	178	=back
177		179
178	=head2 SIMPLE COROUTINE CREATION	180	=head1 SIMPLE CORO CREATION
179		181
180	=over 4	182	=over 4
181		183
182	=item async { ... } [@args...]	184	=item async { ... } [@args...]
183		185
184	Create a new coroutine and return it's coroutine object (usually	186	Create a new coro and return its Coro object (usually
185	unused). The coroutine will be put into the ready queue, so	187	unused). The coro will be put into the ready queue, so
186	it will start running automatically on the next scheduler run.	188	it will start running automatically on the next scheduler run.
187		189
188	The first argument is a codeblock/closure that should be executed in the	190	The first argument is a codeblock/closure that should be executed in the
189	coroutine. When it returns argument returns the coroutine is automatically	191	coro. When it returns argument returns the coro is automatically
190	terminated.	192	terminated.
191		193
192	The remaining arguments are passed as arguments to the closure.	194	The remaining arguments are passed as arguments to the closure.
193		195
194	See the C<Coro::State::new> constructor for info about the coroutine	196	See the C<Coro::State::new> constructor for info about the coro
195	environment in which coroutines are executed.	197	environment in which coro are executed.
196		198
197	Calling C<exit> in a coroutine will do the same as calling exit outside	199	Calling C<exit> in a coro will do the same as calling exit outside
198	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
199	just as it would in the main program.	201	just as it would in the main program.
200		202
201	If you do not want that, you can provide a default C<die> handler, or	203	If you do not want that, you can provide a default C<die> handler, or
202	simply avoid dieing (by use of C<eval>).	204	simply avoid dieing (by use of C<eval>).
203		205
204	Example: Create a new coroutine that just prints its arguments.	206	Example: Create a new coro that just prints its arguments.
205		207
206	async {	208	async {
207	print "@_\n";	209	print "@_\n";
208	} 1,2,3,4;	210	} 1,2,3,4;
209		211
…		…
215	$coro	217	$coro
216	}	218	}
217		219
218	=item async_pool { ... } [@args...]	220	=item async_pool { ... } [@args...]
219		221
220	Similar to C<async>, but uses a coroutine pool, so you should not call	222	Similar to C<async>, but uses a coro pool, so you should not call
221	terminate or join on it (although you are allowed to), and you get a	223	terminate or join on it (although you are allowed to), and you get a
222	coroutine that might have executed other code already (which can be good	224	coro that might have executed other code already (which can be good
223	or bad :).	225	or bad :).
224		226
225	On the plus side, this function is faster than creating (and destroying)	227	On the plus side, this function is about twice as fast as creating (and
226	a completely new coroutine, so if you need a lot of generic coroutines in	228	destroying) a completely new coro, so if you need a lot of generic
227	quick successsion, use C<async_pool>, not C<async>.	229	coros in quick successsion, use C<async_pool>, not C<async>.
228		230
229	The code block is executed in an C<eval> context and a warning will be	231	The code block is executed in an C<eval> context and a warning will be
230	issued in case of an exception instead of terminating the program, as	232	issued in case of an exception instead of terminating the program, as
231	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	233	C<async> does. As the coro is being reused, stuff like C<on_destroy>
232	will not work in the expected way, unless you call terminate or cancel,	234	will not work in the expected way, unless you call terminate or cancel,
233	which somehow defeats the purpose of pooling (but is fine in the	235	which somehow defeats the purpose of pooling (but is fine in the
234	exceptional case).	236	exceptional case).
235		237
236	The priority will be reset to C<0> after each run, tracing will be	238	The priority will be reset to C<0> after each run, tracing will be
237	disabled, the description will be reset and the default output filehandle	239	disabled, the description will be reset and the default output filehandle
238	gets restored, so you can change all these. Otherwise the coroutine will	240	gets restored, so you can change all these. Otherwise the coro will
239	be re-used "as-is": most notably if you change other per-coroutine global	241	be re-used "as-is": most notably if you change other per-coro global
240	stuff such as C<$/> you I<must needs> to revert that change, which is most	242	stuff such as C<$/> you I<must needs> revert that change, which is most
241	simply done by using local as in: C< local $/ >.	243	simply done by using local as in: C<< local $/ >>.
242		244
243	The pool size is limited to C<8> idle coroutines (this can be adjusted by	245	The idle pool size is limited to C<8> idle coros (this can be
244	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	246	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
245	required.	247	coros as required.
246		248
247	If you are concerned about pooled coroutines growing a lot because a	249	If you are concerned about pooled coros growing a lot because a
248	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	250	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
249	{ terminate }> once per second or so to slowly replenish the pool. In	251	{ terminate }> once per second or so to slowly replenish the pool. In
250	addition to that, when the stacks used by a handler grows larger than 16kb	252	addition to that, when the stacks used by a handler grows larger than 32kb
251	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	253	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
252		254
253	=cut	255	=cut
254		256
255	our $POOL_SIZE = 8;	257	our $POOL_SIZE = 8;
256	our $POOL_RSS = 16 * 1024;	258	our $POOL_RSS = 32 * 1024;
257	our @async_pool;	259	our @async_pool;
258		260
259	sub pool_handler {	261	sub pool_handler {
260	my $cb;
261
262	while () {	262	while () {
263	eval {	263	eval {
264	while () {	264	&{&_pool_handler} while 1;
265	_pool_1 $cb;
266	&$cb;
267	_pool_2 $cb;
268	&schedule;
269	}
270	};	265	};
271		266
272	if ($@) {
273	last if $@ eq "\3async_pool terminate\2\n";
274	warn $@;	267	warn $@ if $@;
275	}
276	}	268	}
277	}	269	}
278		270
279	sub async_pool(&@) {
280	# this is also inlined into the unlock_scheduler
281	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
282
283	$coro->{_invoke} = [@_];
284	$coro->ready;
285
286	$coro
287	}
288
289	=back	271	=back
290		272
291	=head2 STATIC METHODS	273	=head1 STATIC METHODS
292		274
293	Static methods are actually functions that operate on the current coroutine.	275	Static methods are actually functions that implicitly operate on the
		276	current coro.
294		277
295	=over 4	278	=over 4
296		279
297	=item schedule	280	=item schedule
298		281
299	Calls the scheduler. The scheduler will find the next coroutine that is	282	Calls the scheduler. The scheduler will find the next coro that is
300	to be run from the ready queue and switches to it. The next coroutine	283	to be run from the ready queue and switches to it. The next coro
301	to be run is simply the one with the highest priority that is longest	284	to be run is simply the one with the highest priority that is longest
302	in its ready queue. If there is no coroutine ready, it will clal the	285	in its ready queue. If there is no coro ready, it will clal the
303	C<$Coro::idle> hook.	286	C<$Coro::idle> hook.
304		287
305	Please note that the current coroutine will I<not> be put into the ready	288	Please note that the current coro will I<not> be put into the ready
306	queue, so calling this function usually means you will never be called	289	queue, so calling this function usually means you will never be called
307	again unless something else (e.g. an event handler) calls C<< ->ready >>,	290	again unless something else (e.g. an event handler) calls C<< ->ready >>,
308	thus waking you up.	291	thus waking you up.
309		292
310	This makes C<schedule> I<the> generic method to use to block the current	293	This makes C<schedule> I<the> generic method to use to block the current
311	coroutine and wait for events: first you remember the current coroutine in	294	coro and wait for events: first you remember the current coro in
312	a variable, then arrange for some callback of yours to call C<< ->ready	295	a variable, then arrange for some callback of yours to call C<< ->ready
313	>> on that once some event happens, and last you call C<schedule> to put	296	>> on that once some event happens, and last you call C<schedule> to put
314	yourself to sleep. Note that a lot of things can wake your coroutine up,	297	yourself to sleep. Note that a lot of things can wake your coro up,
315	so you need to check whether the event indeed happened, e.g. by storing the	298	so you need to check whether the event indeed happened, e.g. by storing the
316	status in a variable.	299	status in a variable.
317		300
318	The canonical way to wait on external events is this:	301	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
319		302
320	{	303	=item cede
321	# remember current coroutine
322	my $current = $Coro::current;
323		304
324	# register a hypothetical event handler	305	"Cede" to other coros. This function puts the current coro into
325	on_event_invoke sub {	306	the ready queue and calls C<schedule>, which has the effect of giving
326	# wake up sleeping coroutine	307	up the current "timeslice" to other coros of the same or higher
327	$current->ready;	308	priority. Once your coro gets its turn again it will automatically be
328	undef $current;	309	resumed.
		310
		311	This function is often called C<yield> in other languages.
		312
		313	=item Coro::cede_notself
		314
		315	Works like cede, but is not exported by default and will cede to I<any>
		316	coro, regardless of priority. This is useful sometimes to ensure
		317	progress is made.
		318
		319	=item terminate [arg...]
		320
		321	Terminates the current coro with the given status values (see L<cancel>).
		322
		323	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		324
		325	These function install enter and leave winders in the current scope. The
		326	enter block will be executed when on_enter is called and whenever the
		327	current coro is re-entered by the scheduler, while the leave block is
		328	executed whenever the current coro is blocked by the scheduler, and
		329	also when the containing scope is exited (by whatever means, be it exit,
		330	die, last etc.).
		331
		332	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		333	BLOCKs>. That means: do not even think about calling C<die> without an
		334	eval, and do not even think of entering the scheduler in any way.
		335
		336	Since both BLOCKs are tied to the current scope, they will automatically
		337	be removed when the current scope exits.
		338
		339	These functions implement the same concept as C<dynamic-wind> in scheme
		340	does, and are useful when you want to localise some resource to a specific
		341	coro.
		342
		343	They slow down coro switching considerably for coros that use
		344	them (But coro switching is still reasonably fast if the handlers are
		345	fast).
		346
		347	These functions are best understood by an example: The following function
		348	will change the current timezone to "Antarctica/South_Pole", which
		349	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		350	which remember/change the current timezone and restore the previous
		351	value, respectively, the timezone is only changed for the coro that
		352	installed those handlers.
		353
		354	use POSIX qw(tzset);
		355
		356	async {
		357	my $old_tz; # store outside TZ value here
		358
		359	Coro::on_enter {
		360	$old_tz = $ENV{TZ}; # remember the old value
		361
		362	$ENV{TZ} = "Antarctica/South_Pole";
		363	tzset; # enable new value
329	};	364	};
330		365
331	# call schedule until event occurred.	366	Coro::on_leave {
332	# in case we are woken up for other reasons	367	$ENV{TZ} = $old_tz;
333	# (current still defined), loop.	368	tzset; # restore old value
334	Coro::schedule while $current;	369	};
		370
		371	# at this place, the timezone is Antarctica/South_Pole,
		372	# without disturbing the TZ of any other coro.
335	}	373	};
336		374
337	=item cede	375	This can be used to localise about any resource (locale, uid, current
338		376	working directory etc.) to a block, despite the existance of other
339	"Cede" to other coroutines. This function puts the current coroutine into	377	coros.
340	the ready queue and calls C<schedule>, which has the effect of giving
341	up the current "timeslice" to other coroutines of the same or higher
342	priority. Once your coroutine gets its turn again it will automatically be
343	resumed.
344
345	This function is often called C<yield> in other languages.
346
347	=item Coro::cede_notself
348
349	Works like cede, but is not exported by default and will cede to I<any>
350	coroutine, regardless of priority. This is useful sometimes to ensure
351	progress is made.
352
353	=item terminate [arg...]
354
355	Terminates the current coroutine with the given status values (see L<cancel>).
356		378
357	=item killall	379	=item killall
358		380
359	Kills/terminates/cancels all coroutines except the currently running	381	Kills/terminates/cancels all coros except the currently running one.
360	one. This is useful after a fork, either in the child or the parent, as
361	usually only one of them should inherit the running coroutines.
362		382
363	Note that while this will try to free some of the main programs resources,	383	Note that while this will try to free some of the main interpreter
		384	resources if the calling coro isn't the main coro, but one
364	you cannot free all of them, so if a coroutine that is not the main	385	cannot free all of them, so if a coro that is not the main coro
365	program calls this function, there will be some one-time resource leak.	386	calls this function, there will be some one-time resource leak.
366		387
367	=cut	388	=cut
368
369	sub terminate {
370	$current->cancel (@_);
371	}
372		389
373	sub killall {	390	sub killall {
374	for (Coro::State::list) {	391	for (Coro::State::list) {
375	$_->cancel	392	$_->cancel
376	if $_ != $current && UNIVERSAL::isa $_, "Coro";	393	if $_ != $current && UNIVERSAL::isa $_, "Coro";
377	}	394	}
378	}	395	}
379		396
380	=back	397	=back
381		398
382	=head2 COROUTINE METHODS	399	=head1 CORO OBJECT METHODS
383		400
384	These are the methods you can call on coroutine objects (or to create	401	These are the methods you can call on coro objects (or to create
385	them).	402	them).
386		403
387	=over 4	404	=over 4
388		405
389	=item new Coro \&sub [, @args...]	406	=item new Coro \&sub [, @args...]
390		407
391	Create a new coroutine and return it. When the sub returns, the coroutine	408	Create a new coro and return it. When the sub returns, the coro
392	automatically terminates as if C<terminate> with the returned values were	409	automatically terminates as if C<terminate> with the returned values were
393	called. To make the coroutine run you must first put it into the ready	410	called. To make the coro run you must first put it into the ready
394	queue by calling the ready method.	411	queue by calling the ready method.
395		412
396	See C<async> and C<Coro::State::new> for additional info about the	413	See C<async> and C<Coro::State::new> for additional info about the
397	coroutine environment.	414	coro environment.
398		415
399	=cut	416	=cut
400		417
401	sub _run_coro {	418	sub _coro_run {
402	terminate &{+shift};	419	terminate &{+shift};
403	}	420	}
404		421
405	sub new {
406	my $class = shift;
407
408	$class->SUPER::new (\&_run_coro, @_)
409	}
410
411	=item $success = $coroutine->ready	422	=item $success = $coro->ready
412		423
413	Put the given coroutine into the end of its ready queue (there is one	424	Put the given coro into the end of its ready queue (there is one
414	queue for each priority) and return true. If the coroutine is already in	425	queue for each priority) and return true. If the coro is already in
415	the ready queue, do nothing and return false.	426	the ready queue, do nothing and return false.
416		427
417	This ensures that the scheduler will resume this coroutine automatically	428	This ensures that the scheduler will resume this coro automatically
418	once all the coroutines of higher priority and all coroutines of the same	429	once all the coro of higher priority and all coro of the same
419	priority that were put into the ready queue earlier have been resumed.	430	priority that were put into the ready queue earlier have been resumed.
420		431
		432	=item $coro->suspend
		433
		434	Suspends the specified coro. A suspended coro works just like any other
		435	coro, except that the scheduler will not select a suspended coro for
		436	execution.
		437
		438	Suspending a coro can be useful when you want to keep the coro from
		439	running, but you don't want to destroy it, or when you want to temporarily
		440	freeze a coro (e.g. for debugging) to resume it later.
		441
		442	A scenario for the former would be to suspend all (other) coros after a
		443	fork and keep them alive, so their destructors aren't called, but new
		444	coros can be created.
		445
		446	=item $coro->resume
		447
		448	If the specified coro was suspended, it will be resumed. Note that when
		449	the coro was in the ready queue when it was suspended, it might have been
		450	unreadied by the scheduler, so an activation might have been lost.
		451
		452	To avoid this, it is best to put a suspended coro into the ready queue
		453	unconditionally, as every synchronisation mechanism must protect itself
		454	against spurious wakeups, and the one in the Coro family certainly do
		455	that.
		456
421	=item $is_ready = $coroutine->is_ready	457	=item $is_ready = $coro->is_ready
422		458
423	Return whether the coroutine is currently the ready queue or not,	459	Returns true iff the Coro object is in the ready queue. Unless the Coro
		460	object gets destroyed, it will eventually be scheduled by the scheduler.
424		461
		462	=item $is_running = $coro->is_running
		463
		464	Returns true iff the Coro object is currently running. Only one Coro object
		465	can ever be in the running state (but it currently is possible to have
		466	multiple running Coro::States).
		467
		468	=item $is_suspended = $coro->is_suspended
		469
		470	Returns true iff this Coro object has been suspended. Suspended Coros will
		471	not ever be scheduled.
		472
425	=item $coroutine->cancel (arg...)	473	=item $coro->cancel (arg...)
426		474
427	Terminates the given coroutine and makes it return the given arguments as	475	Terminates the given Coro and makes it return the given arguments as
428	status (default: the empty list). Never returns if the coroutine is the	476	status (default: the empty list). Never returns if the Coro is the
429	current coroutine.	477	current Coro.
430		478
431	=cut	479	=cut
432		480
433	sub cancel {	481	sub cancel {
434	my $self = shift;	482	my $self = shift;
435	$self->{_status} = [@_];
436		483
437	if ($current == $self) {	484	if ($current == $self) {
438	push @destroy, $self;	485	terminate @_;
439	$manager->ready;
440	&schedule while 1;
441	} else {	486	} else {
442	$self->_cancel;	487	$self->{_status} = [@_];
		488	Coro::State::cancel $self;
443	}	489	}
444	}	490	}
445		491
		492	=item $coro->schedule_to
		493
		494	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		495	of continuing with the next coro from the ready queue, always switch to
		496	the given coro object (regardless of priority etc.). The readyness
		497	state of that coro isn't changed.
		498
		499	This is an advanced method for special cases - I'd love to hear about any
		500	uses for this one.
		501
		502	=item $coro->cede_to
		503
		504	Like C<schedule_to>, but puts the current coro into the ready
		505	queue. This has the effect of temporarily switching to the given
		506	coro, and continuing some time later.
		507
		508	This is an advanced method for special cases - I'd love to hear about any
		509	uses for this one.
		510
		511	=item $coro->throw ([$scalar])
		512
		513	If C<$throw> is specified and defined, it will be thrown as an exception
		514	inside the coro at the next convenient point in time. Otherwise
		515	clears the exception object.
		516
		517	Coro will check for the exception each time a schedule-like-function
		518	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		519	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		520	detect this case and return early in case an exception is pending.
		521
		522	The exception object will be thrown "as is" with the specified scalar in
		523	C<$@>, i.e. if it is a string, no line number or newline will be appended
		524	(unlike with C<die>).
		525
		526	This can be used as a softer means than C<cancel> to ask a coro to
		527	end itself, although there is no guarantee that the exception will lead to
		528	termination, and if the exception isn't caught it might well end the whole
		529	program.
		530
		531	You might also think of C<throw> as being the moral equivalent of
		532	C<kill>ing a coro with a signal (in this case, a scalar).
		533
446	=item $coroutine->join	534	=item $coro->join
447		535
448	Wait until the coroutine terminates and return any values given to the	536	Wait until the coro terminates and return any values given to the
449	C<terminate> or C<cancel> functions. C<join> can be called concurrently	537	C<terminate> or C<cancel> functions. C<join> can be called concurrently
450	from multiple coroutines, and all will be resumed and given the status	538	from multiple coro, and all will be resumed and given the status
451	return once the C<$coroutine> terminates.	539	return once the C<$coro> terminates.
452		540
453	=cut	541	=cut
454		542
455	sub join {	543	sub join {
456	my $self = shift;	544	my $self = shift;
…		…
467	}	555	}
468		556
469	wantarray ? @{$self->{_status}} : $self->{_status}[0];	557	wantarray ? @{$self->{_status}} : $self->{_status}[0];
470	}	558	}
471		559
472	=item $coroutine->on_destroy (\&cb)	560	=item $coro->on_destroy (\&cb)
473		561
474	Registers a callback that is called when this coroutine gets destroyed,	562	Registers a callback that is called when this coro gets destroyed,
475	but before it is joined. The callback gets passed the terminate arguments,	563	but before it is joined. The callback gets passed the terminate arguments,
476	if any, and I<must not> die, under any circumstances.	564	if any, and I<must not> die, under any circumstances.
477		565
478	=cut	566	=cut
479		567
…		…
481	my ($self, $cb) = @_;	569	my ($self, $cb) = @_;
482		570
483	push @{ $self->{_on_destroy} }, $cb;	571	push @{ $self->{_on_destroy} }, $cb;
484	}	572	}
485		573
486	=item $oldprio = $coroutine->prio ($newprio)	574	=item $oldprio = $coro->prio ($newprio)
487		575
488	Sets (or gets, if the argument is missing) the priority of the	576	Sets (or gets, if the argument is missing) the priority of the
489	coroutine. Higher priority coroutines get run before lower priority	577	coro. Higher priority coro get run before lower priority
490	coroutines. Priorities are small signed integers (currently -4 .. +3),	578	coro. Priorities are small signed integers (currently -4 .. +3),
491	that you can refer to using PRIO_xxx constants (use the import tag :prio	579	that you can refer to using PRIO_xxx constants (use the import tag :prio
492	to get then):	580	to get then):
493		581
494	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	582	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
495	3 > 1 > 0 > -1 > -3 > -4	583	3 > 1 > 0 > -1 > -3 > -4
496		584
497	# set priority to HIGH	585	# set priority to HIGH
498	current->prio(PRIO_HIGH);	586	current->prio (PRIO_HIGH);
499		587
500	The idle coroutine ($Coro::idle) always has a lower priority than any	588	The idle coro ($Coro::idle) always has a lower priority than any
501	existing coroutine.	589	existing coro.
502		590
503	Changing the priority of the current coroutine will take effect immediately,	591	Changing the priority of the current coro will take effect immediately,
504	but changing the priority of coroutines in the ready queue (but not	592	but changing the priority of coro in the ready queue (but not
505	running) will only take effect after the next schedule (of that	593	running) will only take effect after the next schedule (of that
506	coroutine). This is a bug that will be fixed in some future version.	594	coro). This is a bug that will be fixed in some future version.
507		595
508	=item $newprio = $coroutine->nice ($change)	596	=item $newprio = $coro->nice ($change)
509		597
510	Similar to C<prio>, but subtract the given value from the priority (i.e.	598	Similar to C<prio>, but subtract the given value from the priority (i.e.
511	higher values mean lower priority, just as in unix).	599	higher values mean lower priority, just as in unix).
512		600
513	=item $olddesc = $coroutine->desc ($newdesc)	601	=item $olddesc = $coro->desc ($newdesc)
514		602
515	Sets (or gets in case the argument is missing) the description for this	603	Sets (or gets in case the argument is missing) the description for this
516	coroutine. This is just a free-form string you can associate with a coroutine.	604	coro. This is just a free-form string you can associate with a
		605	coro.
517		606
518	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	607	This method simply sets the C<< $coro->{desc} >> member to the given
519	can modify this member directly if you wish.	608	string. You can modify this member directly if you wish.
520
521	=item $coroutine->throw ([$scalar])
522
523	If C<$throw> is specified and defined, it will be thrown as an exception
524	inside the coroutine at the next convinient point in time (usually after
525	it gains control at the next schedule/transfer/cede). Otherwise clears the
526	exception object.
527
528	The exception object will be thrown "as is" with the specified scalar in
529	C<$@>, i.e. if it is a string, no line number or newline will be appended
530	(unlike with C<die>).
531
532	This can be used as a softer means than C<cancel> to ask a coroutine to
533	end itself, although there is no guarentee that the exception will lead to
534	termination, and if the exception isn't caught it might well end the whole
535	program.
536		609
537	=cut	610	=cut
538		611
539	sub desc {	612	sub desc {
540	my $old = $_[0]{desc};	613	my $old = $_[0]{desc};
541	$_[0]{desc} = $_[1] if @_ > 1;	614	$_[0]{desc} = $_[1] if @_ > 1;
542	$old;	615	$old;
543	}	616	}
544		617
		618	sub transfer {
		619	require Carp;
		620	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		621	}
		622
545	=back	623	=back
546		624
547	=head2 GLOBAL FUNCTIONS	625	=head1 GLOBAL FUNCTIONS
548		626
549	=over 4	627	=over 4
550		628
551	=item Coro::nready	629	=item Coro::nready
552		630
553	Returns the number of coroutines that are currently in the ready state,	631	Returns the number of coro that are currently in the ready state,
554	i.e. that can be switched to by calling C<schedule> directory or	632	i.e. that can be switched to by calling C<schedule> directory or
555	indirectly. The value C<0> means that the only runnable coroutine is the	633	indirectly. The value C<0> means that the only runnable coro is the
556	currently running one, so C<cede> would have no effect, and C<schedule>	634	currently running one, so C<cede> would have no effect, and C<schedule>
557	would cause a deadlock unless there is an idle handler that wakes up some	635	would cause a deadlock unless there is an idle handler that wakes up some
558	coroutines.	636	coro.
559		637
560	=item my $guard = Coro::guard { ... }	638	=item my $guard = Coro::guard { ... }
561		639
562	This creates and returns a guard object. Nothing happens until the object	640	This function still exists, but is deprecated. Please use the
563	gets destroyed, in which case the codeblock given as argument will be	641	C<Guard::guard> function instead.
564	executed. This is useful to free locks or other resources in case of a
565	runtime error or when the coroutine gets canceled, as in both cases the
566	guard block will be executed. The guard object supports only one method,
567	C<< ->cancel >>, which will keep the codeblock from being executed.
568		642
569	Example: set some flag and clear it again when the coroutine gets canceled
570	or the function returns:
571
572	sub do_something {
573	my $guard = Coro::guard { $busy = 0 };
574	$busy = 1;
575
576	# do something that requires $busy to be true
577	}
578
579	=cut	643	=cut
580		644
581	sub guard(&) {	645	BEGIN { *guard = \&Guard::guard }
582	bless \(my $cb = $_[0]), "Coro::guard"
583	}
584
585	sub Coro::guard::cancel {
586	${$_[0]} = sub { };
587	}
588
589	sub Coro::guard::DESTROY {
590	${$_[0]}->();
591	}
592
593		646
594	=item unblock_sub { ... }	647	=item unblock_sub { ... }
595		648
596	This utility function takes a BLOCK or code reference and "unblocks" it,	649	This utility function takes a BLOCK or code reference and "unblocks" it,
597	returning a new coderef. Unblocking means that calling the new coderef	650	returning a new coderef. Unblocking means that calling the new coderef
598	will return immediately without blocking, returning nothing, while the	651	will return immediately without blocking, returning nothing, while the
599	original code ref will be called (with parameters) from within another	652	original code ref will be called (with parameters) from within another
600	coroutine.	653	coro.
601		654
602	The reason this function exists is that many event libraries (such as the	655	The reason this function exists is that many event libraries (such as the
603	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	656	venerable L<Event\|Event> module) are not thread-safe (a weaker form
604	of thread-safety). This means you must not block within event callbacks,	657	of reentrancy). This means you must not block within event callbacks,
605	otherwise you might suffer from crashes or worse. The only event library	658	otherwise you might suffer from crashes or worse. The only event library
606	currently known that is safe to use without C<unblock_sub> is L<EV>.	659	currently known that is safe to use without C<unblock_sub> is L<EV>.
607		660
608	This function allows your callbacks to block by executing them in another	661	This function allows your callbacks to block by executing them in another
609	coroutine where it is safe to block. One example where blocking is handy	662	coro where it is safe to block. One example where blocking is handy
610	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	663	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
611	disk, for example.	664	disk, for example.
612		665
613	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	666	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
614	creating event callbacks that want to block.	667	creating event callbacks that want to block.
615		668
616	If your handler does not plan to block (e.g. simply sends a message to	669	If your handler does not plan to block (e.g. simply sends a message to
617	another coroutine, or puts some other coroutine into the ready queue),	670	another coro, or puts some other coro into the ready queue), there is
618	there is no reason to use C<unblock_sub>.	671	no reason to use C<unblock_sub>.
619		672
620	Note that you also need to use C<unblock_sub> for any other callbacks that	673	Note that you also need to use C<unblock_sub> for any other callbacks that
621	are indirectly executed by any C-based event loop. For example, when you	674	are indirectly executed by any C-based event loop. For example, when you
622	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it	675	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
623	provides callbacks that are the result of some event callback, then you	676	provides callbacks that are the result of some event callback, then you
…		…
632	# return immediately and can be reused) and because we cannot cede	685	# return immediately and can be reused) and because we cannot cede
633	# inside an event callback.	686	# inside an event callback.
634	our $unblock_scheduler = new Coro sub {	687	our $unblock_scheduler = new Coro sub {
635	while () {	688	while () {
636	while (my $cb = pop @unblock_queue) {	689	while (my $cb = pop @unblock_queue) {
637	# this is an inlined copy of async_pool	690	&async_pool (@$cb);
638	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
639		691
640	$coro->{_invoke} = $cb;
641	$coro->ready;
642	cede; # for short-lived callbacks, this reduces pressure on the coro pool	692	# for short-lived callbacks, this reduces pressure on the coro pool
		693	# as the chance is very high that the async_poll coro will be back
		694	# in the idle state when cede returns
		695	cede;
643	}	696	}
644	schedule; # sleep well	697	schedule; # sleep well
645	}	698	}
646	};	699	};
647	$unblock_scheduler->desc ("[unblock_sub scheduler]");	700	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
648		701
649	sub unblock_sub(&) {	702	sub unblock_sub(&) {
650	my $cb = shift;	703	my $cb = shift;
651		704
652	sub {	705	sub {
653	unshift @unblock_queue, [$cb, @_];	706	unshift @unblock_queue, [$cb, @_];
654	$unblock_scheduler->ready;	707	$unblock_scheduler->ready;
655	}	708	}
656	}	709	}
657		710
		711	=item $cb = Coro::rouse_cb
		712
		713	Create and return a "rouse callback". That's a code reference that,
		714	when called, will remember a copy of its arguments and notify the owner
		715	coro of the callback.
		716
		717	See the next function.
		718
		719	=item @args = Coro::rouse_wait [$cb]
		720
		721	Wait for the specified rouse callback (or the last one that was created in
		722	this coro).
		723
		724	As soon as the callback is invoked (or when the callback was invoked
		725	before C<rouse_wait>), it will return the arguments originally passed to
		726	the rouse callback.
		727
		728	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		729
658	=back	730	=back
659		731
660	=cut	732	=cut
661		733
662	1;	734	1;
663		735
		736	=head1 HOW TO WAIT FOR A CALLBACK
		737
		738	It is very common for a coro to wait for some callback to be
		739	called. This occurs naturally when you use coro in an otherwise
		740	event-based program, or when you use event-based libraries.
		741
		742	These typically register a callback for some event, and call that callback
		743	when the event occured. In a coro, however, you typically want to
		744	just wait for the event, simplyifying things.
		745
		746	For example C<< AnyEvent->child >> registers a callback to be called when
		747	a specific child has exited:
		748
		749	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		750
		751	But from within a coro, you often just want to write this:
		752
		753	my $status = wait_for_child $pid;
		754
		755	Coro offers two functions specifically designed to make this easy,
		756	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		757
		758	The first function, C<rouse_cb>, generates and returns a callback that,
		759	when invoked, will save its arguments and notify the coro that
		760	created the callback.
		761
		762	The second function, C<rouse_wait>, waits for the callback to be called
		763	(by calling C<schedule> to go to sleep) and returns the arguments
		764	originally passed to the callback.
		765
		766	Using these functions, it becomes easy to write the C<wait_for_child>
		767	function mentioned above:
		768
		769	sub wait_for_child($) {
		770	my ($pid) = @_;
		771
		772	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		773
		774	my ($rpid, $rstatus) = Coro::rouse_wait;
		775	$rstatus
		776	}
		777
		778	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		779	you can roll your own, using C<schedule>:
		780
		781	sub wait_for_child($) {
		782	my ($pid) = @_;
		783
		784	# store the current coro in $current,
		785	# and provide result variables for the closure passed to ->child
		786	my $current = $Coro::current;
		787	my ($done, $rstatus);
		788
		789	# pass a closure to ->child
		790	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		791	$rstatus = $_[1]; # remember rstatus
		792	$done = 1; # mark $rstatus as valud
		793	});
		794
		795	# wait until the closure has been called
		796	schedule while !$done;
		797
		798	$rstatus
		799	}
		800
		801
664	=head1 BUGS/LIMITATIONS	802	=head1 BUGS/LIMITATIONS
665		803
		804	=over 4
		805
		806	=item fork with pthread backend
		807
		808	When Coro is compiled using the pthread backend (which isn't recommended
		809	but required on many BSDs as their libcs are completely broken), then
		810	coro will not survive a fork. There is no known workaround except to
		811	fix your libc and use a saner backend.
		812
		813	=item perl process emulation ("threads")
		814
666	This module is not perl-pseudo-thread-safe. You should only ever use this	815	This module is not perl-pseudo-thread-safe. You should only ever use this
667	module from the same thread (this requirement might be removed in the	816	module from the first thread (this requirement might be removed in the
668	future to allow per-thread schedulers, but Coro::State does not yet allow	817	future to allow per-thread schedulers, but Coro::State does not yet allow
669	this). I recommend disabling thread support and using processes, as this	818	this). I recommend disabling thread support and using processes, as having
670	is much faster and uses less memory.	819	the windows process emulation enabled under unix roughly halves perl
		820	performance, even when not used.
		821
		822	=item coro switching is not signal safe
		823
		824	You must not switch to another coro from within a signal handler
		825	(only relevant with %SIG - most event libraries provide safe signals).
		826
		827	That means you I<MUST NOT> call any function that might "block" the
		828	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		829	anything that calls those. Everything else, including calling C<ready>,
		830	works.
		831
		832	=back
		833
671		834
672	=head1 SEE ALSO	835	=head1 SEE ALSO
673		836
674	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.	837	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
675		838
676	Debugging: L<Coro::Debug>.	839	Debugging: L<Coro::Debug>.
677		840
678	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	841	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
679		842
680	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	843	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		844	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
681		845
682	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.	846	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
683		847
684	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.	848	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		849	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		850	L<Coro::Select>.
685		851
686	XS API: L<Coro::MakeMaker>.	852	XS API: L<Coro::MakeMaker>.
687		853
688	Low level Configuration, Coroutine Environment: L<Coro::State>.	854	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
689		855
690	=head1 AUTHOR	856	=head1 AUTHOR
691		857
692	Marc Lehmann <schmorp@schmorp.de>	858	Marc Lehmann <schmorp@schmorp.de>
693	http://home.schmorp.de/	859	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs. Revision 1.253 by root, Fri May 29 07:01:18 2009 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs.
Revision 1.253 by root, Fri May 29 07:01:18 2009 UTC