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

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Revision 1.181 by root, Fri May 9 22:04:37 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	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
31	threads but don't (in general) run in parallel at the same time even	32	manpage. This manpage mainly contains reference information.
32	on SMP machines. The specific flavor of coroutine used in this module
33	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much
36	safer and easier than threads programming.
37		33
38	Unlike a normal perl program, however, coroutines allow you to have	34	This module collection manages continuations in general, most often in
39	multiple running interpreters that share data, which is especially useful	35	the form of cooperative threads (also called coros, or simply "coro"
40	to code pseudo-parallel processes, such as multiple HTTP-GET requests	36	in the documentation). They are similar to kernel threads but don't (in
41	running concurrently.	37	general) run in parallel at the same time even on SMP machines. The
		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.
42		43
43	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
44	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
45	emulation coming from the Windows platform: On standard operating systems	46	as processes), Coro provides a full shared address space, which makes
46	they serve no purpose whatsoever, except by making your programs slow and	47	communication between threads very easy. And Coro's threads are fast,
47	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
48	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.
49		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
50	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
51	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
52	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
53	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.
54		67
55	=cut	68	=cut
56		69
57	package Coro;	70	package Coro;
58		71
59	use strict;	72	use strict qw(vars subs);
60	no warnings "uninitialized";	73	no warnings "uninitialized";
61		74
		75	use Guard ();
		76
62	use Coro::State;	77	use Coro::State;
63		78
64	use base qw(Coro::State Exporter);	79	use base qw(Coro::State Exporter);
65		80
66	our $idle; # idle handler	81	our $idle; # idle handler
67	our $main; # main coroutine	82	our $main; # main coro
68	our $current; # current coroutine	83	our $current; # current coro
69		84
70	our $VERSION = 4.6;	85	our $VERSION = 5.132;
71		86
72	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
73	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
74	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
75	);	90	);
76	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
77		92
		93	=head1 GLOBAL VARIABLES
		94
78	=over 4	95	=over 4
79		96
80	=item $Coro::main	97	=item $Coro::main
81		98
82	This variable stores the coroutine object that represents the main	99	This variable stores the Coro object that represents the main
83	program. While you cna C<ready> it and do most other things you can do to	100	program. While you cna C<ready> it and do most other things you can do to
84	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	101	coro, it is mainly useful to compare again C<$Coro::current>, to see
85	wether you are running in the main program or not.	102	whether you are running in the main program or not.
86		103
87	=cut	104	=cut
88		105
89	$main = new Coro;	106	# $main is now being initialised by Coro::State
90		107
91	=item $Coro::current	108	=item $Coro::current
92		109
93	The coroutine object representing the current coroutine (the last	110	The Coro object representing the current coro (the last
94	coroutine that the Coro scheduler switched to). The initial value is	111	coro that the Coro scheduler switched to). The initial value is
95	C<$main> (of course).	112	C<$Coro::main> (of course).
96		113
97	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
98	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
99	not otherwise modify the variable itself.	116	not otherwise modify the variable itself.
100		117
101	=cut	118	=cut
102		119
103	$main->{desc} = "[main::]";
104
105	# maybe some other module used Coro::Specific before...
106	$main->{_specific} = $current->{_specific}
107	if $current;
108
109	_set_current $main;
110
111	sub current() { $current } # [DEPRECATED]	120	sub current() { $current } # [DEPRECATED]
112		121
113	=item $Coro::idle	122	=item $Coro::idle
114		123
115	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
116	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
117	pretty low-level functionality.	126	pretty low-level functionality.
118		127
119	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
120	finds no ready coroutines to run. The default implementation prints	131	ready coros to run. The default implementation prints "FATAL:
121	"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
122	to continue.	133	continue.
123		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
124	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
125	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
126	coroutine so the scheduler can run it.	141	coro so the scheduler can run it.
127		142
128	Note that the callback I<must not>, under any circumstances, block	143	Note that the callback I<must not>, under any circumstances, block
129	the current coroutine. Normally, this is achieved by having an "idle	144	the current coro. Normally, this is achieved by having an "idle
130	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
131	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.
132		148
133	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
134	technique.	150	technique.
135		151
136	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
…		…
141	$idle = sub {	157	$idle = sub {
142	require Carp;	158	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	159	Carp::croak ("FATAL: deadlock detected");
144	};	160	};
145		161
146	sub _cancel {
147	my ($self) = @_;
148
149	# free coroutine data and mark as destructed
150	$self->_destroy
151	or return;
152
153	# call all destruction callbacks
154	$_->(@{$self->{_status}})
155	for @{(delete $self->{_on_destroy}) \|\| []};
156	}
157
158	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
159	# cannot destroy itself.	163	# cannot destroy itself.
160	my @destroy;	164	our @destroy;
161	my $manager;	165	our $manager;
162		166
163	$manager = new Coro sub {	167	$manager = new Coro sub {
164	while () {	168	while () {
165	(shift @destroy)->_cancel	169	Coro::State::cancel shift @destroy
166	while @destroy;	170	while @destroy;
167		171
168	&schedule;	172	&schedule;
169	}	173	}
170	};	174	};
171	$manager->desc ("[coro manager]");	175	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	176	$manager->prio (PRIO_MAX);
173		177
174	=back	178	=back
175		179
176	=head2 SIMPLE COROUTINE CREATION	180	=head1 SIMPLE CORO CREATION
177		181
178	=over 4	182	=over 4
179		183
180	=item async { ... } [@args...]	184	=item async { ... } [@args...]
181		185
182	Create a new coroutine and return it's coroutine object (usually	186	Create a new coro and return its Coro object (usually
183	unused). The coroutine will be put into the ready queue, so	187	unused). The coro will be put into the ready queue, so
184	it will start running automatically on the next scheduler run.	188	it will start running automatically on the next scheduler run.
185		189
186	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
187	coroutine. When it returns argument returns the coroutine is automatically	191	coro. When it returns argument returns the coro is automatically
188	terminated.	192	terminated.
189		193
190	The remaining arguments are passed as arguments to the closure.	194	The remaining arguments are passed as arguments to the closure.
191		195
192	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
193	environment in which coroutines are executed.	197	environment in which coro are executed.
194		198
195	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
196	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
197	just as it would in the main program.	201	just as it would in the main program.
198		202
199	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
200	simply avoid dieing (by use of C<eval>).	204	simply avoid dieing (by use of C<eval>).
201		205
202	Example: Create a new coroutine that just prints its arguments.	206	Example: Create a new coro that just prints its arguments.
203		207
204	async {	208	async {
205	print "@_\n";	209	print "@_\n";
206	} 1,2,3,4;	210	} 1,2,3,4;
207		211
…		…
213	$coro	217	$coro
214	}	218	}
215		219
216	=item async_pool { ... } [@args...]	220	=item async_pool { ... } [@args...]
217		221
218	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
219	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
220	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
221	or bad :).	225	or bad :).
222		226
223	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
224	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
225	quick successsion, use C<async_pool>, not C<async>.	229	coros in quick successsion, use C<async_pool>, not C<async>.
226		230
227	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
228	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
229	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>
230	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,
231	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
232	exceptional case).	236	exceptional case).
233		237
234	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
235	disabled, the description will be reset and the default output filehandle	239	disabled, the description will be reset and the default output filehandle
236	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
237	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
238	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
239	simply done by using local as in: C< local $/ >.	243	simply done by using local as in: C<< local $/ >>.
240		244
241	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
242	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
243	required.	247	coros as required.
244		248
245	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
246	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
247	{ 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
248	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
249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	253	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
250		254
251	=cut	255	=cut
252		256
253	our $POOL_SIZE = 8;	257	our $POOL_SIZE = 8;
254	our $POOL_RSS = 16 * 1024;	258	our $POOL_RSS = 32 * 1024;
255	our @async_pool;	259	our @async_pool;
256		260
257	sub pool_handler {	261	sub pool_handler {
258	my $cb;
259
260	while () {	262	while () {
261	eval {	263	eval {
262	while () {	264	&{&_pool_handler} while 1;
263	_pool_1 $cb;
264	&$cb;
265	_pool_2 $cb;
266	&schedule;
267	}
268	};	265	};
269		266
270	last if $@ eq "\3async_pool terminate\2\n";
271	warn $@ if $@;	267	warn $@ if $@;
272	}	268	}
273	}	269	}
274		270
275	sub async_pool(&@) {
276	# this is also inlined into the unlock_scheduler
277	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
278
279	$coro->{_invoke} = [@_];
280	$coro->ready;
281
282	$coro
283	}
284
285	=back	271	=back
286		272
287	=head2 STATIC METHODS	273	=head1 STATIC METHODS
288		274
289	Static methods are actually functions that operate on the current coroutine.	275	Static methods are actually functions that implicitly operate on the
		276	current coro.
290		277
291	=over 4	278	=over 4
292		279
293	=item schedule	280	=item schedule
294		281
295	Calls the scheduler. The scheduler will find the next coroutine that is	282	Calls the scheduler. The scheduler will find the next coro that is
296	to be run from the ready queue and switches to it. The next coroutine	283	to be run from the ready queue and switches to it. The next coro
297	to be run is simply the one with the highest priority that is longest	284	to be run is simply the one with the highest priority that is longest
298	in its ready queue. If there is no coroutine ready, it will clal the	285	in its ready queue. If there is no coro ready, it will clal the
299	C<$Coro::idle> hook.	286	C<$Coro::idle> hook.
300		287
301	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
302	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
303	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 >>,
304	thus waking you up.	291	thus waking you up.
305		292
306	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
307	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
308	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
309	>> 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
310	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,
311	so you need to check wether 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
312	status in a variable.	299	status in a variable.
313		300
314	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.
315		302
316	{	303	=item cede
317	# remember current coroutine
318	my $current = $Coro::current;
319		304
320	# register a hypothetical event handler	305	"Cede" to other coros. This function puts the current coro into
321	on_event_invoke sub {	306	the ready queue and calls C<schedule>, which has the effect of giving
322	# wake up sleeping coroutine	307	up the current "timeslice" to other coros of the same or higher
323	$current->ready;	308	priority. Once your coro gets its turn again it will automatically be
324	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
325	};	364	};
326		365
327	# call schedule until event occurred.	366	Coro::on_leave {
328	# in case we are woken up for other reasons	367	$ENV{TZ} = $old_tz;
329	# (current still defined), loop.	368	tzset; # restore old value
330	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.
331	}	373	};
332		374
333	=item cede	375	This can be used to localise about any resource (locale, uid, current
334		376	working directory etc.) to a block, despite the existance of other
335	"Cede" to other coroutines. This function puts the current coroutine into	377	coros.
336	the ready queue and calls C<schedule>, which has the effect of giving
337	up the current "timeslice" to other coroutines of the same or higher
338	priority. Once your coroutine gets its turn again it will automatically be
339	resumed.
340
341	This function is often called C<yield> in other languages.
342
343	=item Coro::cede_notself
344
345	Works like cede, but is not exported by default and will cede to I<any>
346	coroutine, regardless of priority. This is useful sometimes to ensure
347	progress is made.
348
349	=item terminate [arg...]
350
351	Terminates the current coroutine with the given status values (see L<cancel>).
352		378
353	=item killall	379	=item killall
354		380
355	Kills/terminates/cancels all coroutines except the currently running	381	Kills/terminates/cancels all coros except the currently running one.
356	one. This is useful after a fork, either in the child or the parent, as
357	usually only one of them should inherit the running coroutines.
358		382
359	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
360	you cnanot 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
361	program calls this function, there will be some one-time resource leak.	386	calls this function, there will be some one-time resource leak.
362		387
363	=cut	388	=cut
364
365	sub terminate {
366	$current->cancel (@_);
367	}
368		389
369	sub killall {	390	sub killall {
370	for (Coro::State::list) {	391	for (Coro::State::list) {
371	$_->cancel	392	$_->cancel
372	if $_ != $current && UNIVERSAL::isa $_, "Coro";	393	if $_ != $current && UNIVERSAL::isa $_, "Coro";
373	}	394	}
374	}	395	}
375		396
376	=back	397	=back
377		398
378	=head2 COROUTINE METHODS	399	=head1 CORO OBJECT METHODS
379		400
380	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
381	them).	402	them).
382		403
383	=over 4	404	=over 4
384		405
385	=item new Coro \&sub [, @args...]	406	=item new Coro \&sub [, @args...]
386		407
387	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
388	automatically terminates as if C<terminate> with the returned values were	409	automatically terminates as if C<terminate> with the returned values were
389	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
390	queue by calling the ready method.	411	queue by calling the ready method.
391		412
392	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
393	coroutine environment.	414	coro environment.
394		415
395	=cut	416	=cut
396		417
397	sub _run_coro {	418	sub _coro_run {
398	terminate &{+shift};	419	terminate &{+shift};
399	}	420	}
400		421
401	sub new {
402	my $class = shift;
403
404	$class->SUPER::new (\&_run_coro, @_)
405	}
406
407	=item $success = $coroutine->ready	422	=item $success = $coro->ready
408		423
409	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
410	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
411	the ready queue, do nothing and return false.	426	the ready queue, do nothing and return false.
412		427
413	This ensures that the scheduler will resume this coroutine automatically	428	This ensures that the scheduler will resume this coro automatically
414	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
415	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.
416		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
417	=item $is_ready = $coroutine->is_ready	457	=item $is_ready = $coro->is_ready
418		458
419	Return wether 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.
420		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
421	=item $coroutine->cancel (arg...)	473	=item $coro->cancel (arg...)
422		474
423	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
424	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
425	current coroutine.	477	current Coro.
426		478
427	=cut	479	=cut
428		480
429	sub cancel {	481	sub cancel {
430	my $self = shift;	482	my $self = shift;
431	$self->{_status} = [@_];
432		483
433	if ($current == $self) {	484	if ($current == $self) {
434	push @destroy, $self;	485	terminate @_;
435	$manager->ready;
436	&schedule while 1;
437	} else {	486	} else {
438	$self->_cancel;	487	$self->{_status} = [@_];
		488	Coro::State::cancel $self;
439	}	489	}
440	}	490	}
441		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
442	=item $coroutine->join	534	=item $coro->join
443		535
444	Wait until the coroutine terminates and return any values given to the	536	Wait until the coro terminates and return any values given to the
445	C<terminate> or C<cancel> functions. C<join> can be called concurrently	537	C<terminate> or C<cancel> functions. C<join> can be called concurrently
446	from multiple coroutines, and all will be resumed and given the status	538	from multiple coro, and all will be resumed and given the status
447	return once the C<$coroutine> terminates.	539	return once the C<$coro> terminates.
448		540
449	=cut	541	=cut
450		542
451	sub join {	543	sub join {
452	my $self = shift;	544	my $self = shift;
…		…
463	}	555	}
464		556
465	wantarray ? @{$self->{_status}} : $self->{_status}[0];	557	wantarray ? @{$self->{_status}} : $self->{_status}[0];
466	}	558	}
467		559
468	=item $coroutine->on_destroy (\&cb)	560	=item $coro->on_destroy (\&cb)
469		561
470	Registers a callback that is called when this coroutine gets destroyed,	562	Registers a callback that is called when this coro gets destroyed,
471	but before it is joined. The callback gets passed the terminate arguments,	563	but before it is joined. The callback gets passed the terminate arguments,
472	if any, and I<must not> die, under any circumstances.	564	if any, and I<must not> die, under any circumstances.
473		565
474	=cut	566	=cut
475		567
…		…
477	my ($self, $cb) = @_;	569	my ($self, $cb) = @_;
478		570
479	push @{ $self->{_on_destroy} }, $cb;	571	push @{ $self->{_on_destroy} }, $cb;
480	}	572	}
481		573
482	=item $oldprio = $coroutine->prio ($newprio)	574	=item $oldprio = $coro->prio ($newprio)
483		575
484	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
485	coroutine. Higher priority coroutines get run before lower priority	577	coro. Higher priority coro get run before lower priority
486	coroutines. Priorities are small signed integers (currently -4 .. +3),	578	coro. Priorities are small signed integers (currently -4 .. +3),
487	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
488	to get then):	580	to get then):
489		581
490	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
491	3 > 1 > 0 > -1 > -3 > -4	583	3 > 1 > 0 > -1 > -3 > -4
492		584
493	# set priority to HIGH	585	# set priority to HIGH
494	current->prio(PRIO_HIGH);	586	current->prio (PRIO_HIGH);
495		587
496	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
497	existing coroutine.	589	existing coro.
498		590
499	Changing the priority of the current coroutine will take effect immediately,	591	Changing the priority of the current coro will take effect immediately,
500	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
501	running) will only take effect after the next schedule (of that	593	running) will only take effect after the next schedule (of that
502	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.
503		595
504	=item $newprio = $coroutine->nice ($change)	596	=item $newprio = $coro->nice ($change)
505		597
506	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.
507	higher values mean lower priority, just as in unix).	599	higher values mean lower priority, just as in unix).
508		600
509	=item $olddesc = $coroutine->desc ($newdesc)	601	=item $olddesc = $coro->desc ($newdesc)
510		602
511	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
512	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.
513		606
514	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
515	can modify this member directly if you wish.	608	string. You can modify this member directly if you wish.
516
517	=item $coroutine->throw ([$scalar])
518
519	If C<$throw> is specified and defined, it will be thrown as an exception
520	inside the coroutine at the next convinient point in time (usually after
521	it gains control at the next schedule/transfer/cede). Otherwise clears the
522	exception object.
523
524	The exception object will be thrown "as is" with the specified scalar in
525	C<$@>, i.e. if it is a string, no line number or newline will be appended
526	(unlike with C<die>).
527
528	This can be used as a softer means than C<cancel> to ask a coroutine to
529	end itself, although there is no guarentee that the exception will lead to
530	termination, and if the exception isn't caught it might well end the whole
531	program.
532		609
533	=cut	610	=cut
534		611
535	sub desc {	612	sub desc {
536	my $old = $_[0]{desc};	613	my $old = $_[0]{desc};
537	$_[0]{desc} = $_[1] if @_ > 1;	614	$_[0]{desc} = $_[1] if @_ > 1;
538	$old;	615	$old;
539	}	616	}
540		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
541	=back	623	=back
542		624
543	=head2 GLOBAL FUNCTIONS	625	=head1 GLOBAL FUNCTIONS
544		626
545	=over 4	627	=over 4
546		628
547	=item Coro::nready	629	=item Coro::nready
548		630
549	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,
550	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
551	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
552	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>
553	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
554	coroutines.	636	coro.
555		637
556	=item my $guard = Coro::guard { ... }	638	=item my $guard = Coro::guard { ... }
557		639
558	This creates and returns a guard object. Nothing happens until the object	640	This function still exists, but is deprecated. Please use the
559	gets destroyed, in which case the codeblock given as argument will be	641	C<Guard::guard> function instead.
560	executed. This is useful to free locks or other resources in case of a
561	runtime error or when the coroutine gets canceled, as in both cases the
562	guard block will be executed. The guard object supports only one method,
563	C<< ->cancel >>, which will keep the codeblock from being executed.
564		642
565	Example: set some flag and clear it again when the coroutine gets canceled
566	or the function returns:
567
568	sub do_something {
569	my $guard = Coro::guard { $busy = 0 };
570	$busy = 1;
571
572	# do something that requires $busy to be true
573	}
574
575	=cut	643	=cut
576		644
577	sub guard(&) {	645	BEGIN { *guard = \&Guard::guard }
578	bless \(my $cb = $_[0]), "Coro::guard"
579	}
580
581	sub Coro::guard::cancel {
582	${$_[0]} = sub { };
583	}
584
585	sub Coro::guard::DESTROY {
586	${$_[0]}->();
587	}
588
589		646
590	=item unblock_sub { ... }	647	=item unblock_sub { ... }
591		648
592	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,
593	returning a new coderef. Unblocking means that calling the new coderef	650	returning a new coderef. Unblocking means that calling the new coderef
594	will return immediately without blocking, returning nothing, while the	651	will return immediately without blocking, returning nothing, while the
595	original code ref will be called (with parameters) from within another	652	original code ref will be called (with parameters) from within another
596	coroutine.	653	coro.
597		654
598	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
599	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
600	of thread-safety). This means you must not block within event callbacks,	657	of reentrancy). This means you must not block within event callbacks,
601	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
602	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>.
603		660
604	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
605	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
606	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
607	disk, for example.	664	disk, for example.
608		665
609	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
610	creating event callbacks that want to block.	667	creating event callbacks that want to block.
611		668
612	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
613	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
614	there is no reason to use C<unblock_sub>.	671	no reason to use C<unblock_sub>.
		672
		673	Note that you also need to use C<unblock_sub> for any other callbacks that
		674	are indirectly executed by any C-based event loop. For example, when you
		675	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		676	provides callbacks that are the result of some event callback, then you
		677	must not block either, or use C<unblock_sub>.
615		678
616	=cut	679	=cut
617		680
618	our @unblock_queue;	681	our @unblock_queue;
619		682
…		…
622	# return immediately and can be reused) and because we cannot cede	685	# return immediately and can be reused) and because we cannot cede
623	# inside an event callback.	686	# inside an event callback.
624	our $unblock_scheduler = new Coro sub {	687	our $unblock_scheduler = new Coro sub {
625	while () {	688	while () {
626	while (my $cb = pop @unblock_queue) {	689	while (my $cb = pop @unblock_queue) {
627	# this is an inlined copy of async_pool	690	&async_pool (@$cb);
628	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
629		691
630	$coro->{_invoke} = $cb;
631	$coro->ready;
632	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;
633	}	696	}
634	schedule; # sleep well	697	schedule; # sleep well
635	}	698	}
636	};	699	};
637	$unblock_scheduler->desc ("[unblock_sub scheduler]");	700	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
638		701
639	sub unblock_sub(&) {	702	sub unblock_sub(&) {
640	my $cb = shift;	703	my $cb = shift;
641		704
642	sub {	705	sub {
643	unshift @unblock_queue, [$cb, @_];	706	unshift @unblock_queue, [$cb, @_];
644	$unblock_scheduler->ready;	707	$unblock_scheduler->ready;
645	}	708	}
646	}	709	}
647		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
648	=back	730	=back
649		731
650	=cut	732	=cut
651		733
652	1;	734	1;
653		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
654	=head1 BUGS/LIMITATIONS	802	=head1 BUGS/LIMITATIONS
655		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
656	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
657	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
658	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
659	this). I recommend disabling thread support and using processes, as this	818	this). I recommend disabling thread support and using processes, as having
660	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
661		834
662	=head1 SEE ALSO	835	=head1 SEE ALSO
663		836
664	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>.
665		838
666	Debugging: L<Coro::Debug>.	839	Debugging: L<Coro::Debug>.
667		840
668	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	841	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
669		842
670	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>.
671		845
672	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>.
673		847
674	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>.
675		851
676	XS API: L<Coro::MakeMaker>.	852	XS API: L<Coro::MakeMaker>.
677		853
678	Low level Configuration, Coroutine Environment: L<Coro::State>.	854	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
679		855
680	=head1 AUTHOR	856	=head1 AUTHOR
681		857
682	Marc Lehmann <schmorp@schmorp.de>	858	Marc Lehmann <schmorp@schmorp.de>
683	http://home.schmorp.de/	859	http://home.schmorp.de/

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.181 by root, Fri May 9 22:04:37 2008 UTC vs. Revision 1.253 by root, Fri May 29 07:01:18 2009 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.181 by root, Fri May 9 22:04:37 2008 UTC vs.
Revision 1.253 by root, Fri May 29 07:01:18 2009 UTC