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

Comparing Coro/Coro.pm (file contents):
Revision 1.78 by root, Wed Nov 1 01:21:21 2006 UTC vs.
Revision 1.130 by root, Thu Sep 20 12:02:25 2007 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
18		18
19	cede;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
23	This module collection manages coroutines. Coroutines are similar to	23	This module collection manages coroutines. Coroutines are similar
24	threads but don't run in parallel.	24	to threads but don't run in parallel at the same time even on SMP
		25	machines. The specific flavor of coroutine used in this module also
		26	guarantees you that it will not switch between coroutines unless
		27	necessary, at easily-identified points in your program, so locking and
		28	parallel access are rarely an issue, making coroutine programming much
		29	safer than threads programming.
25		30
		31	(Perl, however, does not natively support real threads but instead does a
		32	very slow and memory-intensive emulation of processes using threads. This
		33	is a performance win on Windows machines, and a loss everywhere else).
		34
26	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	37	its own set of lexicals and its own set of perls most important global
29	important global variables.	38	variables.
30		39
31	=cut	40	=cut
32		41
33	package Coro;	42	package Coro;
34		43
35	use strict;	44	use strict;
36	no warnings "uninitialized";	45	no warnings "uninitialized";
37		46
38	use Coro::State;	47	use Coro::State;
39		48
40	use base Exporter::;	49	use base qw(Coro::State Exporter);
41		50
42	our $idle; # idle coroutine	51	our $idle; # idle handler
43	our $main; # main coroutine	52	our $main; # main coroutine
44	our $current; # current coroutine	53	our $current; # current coroutine
45		54
46	our $VERSION = '2.1';	55	our $VERSION = '3.7';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53		62
54	{	63	{
55	my @async;	64	my @async;
56	my $init;	65	my $init;
57		66
58	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
59	sub import {	68	sub import {
60	no strict 'refs';	69	no strict 'refs';
61		70
62	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
63		72
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
95		104
96	$main = new Coro;	105	$main = new Coro;
97		106
98	=item $current (or as function: current)	107	=item $current (or as function: current)
99		108
100	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essential you are encouraged to use the
		114	C<Coro::current> function instead.
101		115
102	=cut	116	=cut
103		117
104	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
105	if ($current) {
106	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
107	}	120	if $current;
108		121
109	$current = $main;	122	_set_current $main;
110		123
111	sub current() { $current }	124	sub current() { $current }
112		125
113	=item $idle	126	=item $idle
114		127
115	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
116	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
117		131
118	=cut	132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
119		135
120	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
121	$idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
122	print STDERR "FATAL: deadlock detected\n";	138
123	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
124	};	144	};
		145
		146	sub _cancel {
		147	my ($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->{destroy_cb}) \|\| []};
		156	}
125		157
126	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
127	# cannot destroy itself.	159	# cannot destroy itself.
128	my @destroy;	160	my @destroy;
129	my $manager;	161	my $manager;
		162
130	$manager = new Coro sub {	163	$manager = new Coro sub {
		164	$current->desc ("[coro manager]");
		165
131	while () {	166	while () {
132	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
133	# while still being able to schedule this coroutine (in case it has
134	# been readied multiple times. this is harmless since the manager
135	# can be called as many times as neccessary and will always
136	# remove itself from the runqueue
137	while (@destroy) {	168	while @destroy;
138	my $coro = pop @destroy;
139	$coro->{status} \|\|= [];
140	$_->ready for @{delete $coro->{join} \|\| []};
141		169
142	# the next line destroys the _coro_state, but keeps the
143	# process itself intact (we basically make it a zombie
144	# process that always runs the manager thread, so it's possible
145	# to transfer() to this process).
146	$coro->{_coro_state} = $manager->{_coro_state};
147	}
148	&schedule;	170	&schedule;
149	}	171	}
150	};	172	};
151		173
		174	$manager->prio (PRIO_MAX);
		175
152	# static methods. not really.	176	# static methods. not really.
153		177
154	=back	178	=back
155		179
156	=head2 STATIC METHODS	180	=head2 STATIC METHODS
157		181
158	Static methods are actually functions that operate on the current process only.	182	Static methods are actually functions that operate on the current coroutine only.
159		183
160	=over 4	184	=over 4
161		185
162	=item async { ... } [@args...]	186	=item async { ... } [@args...]
163		187
164	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
165	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
166	terminated.	190	terminated.
		191
		192	Calling C<exit> in a coroutine will do the same as calling exit outside
		193	the coroutine. Likewise, when the coroutine dies, the program will exit,
		194	just as it would in the main program.
167		195
168	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
169	async {	197	async {
170	print "@_\n";	198	print "@_\n";
171	} 1,2,3,4;	199	} 1,2,3,4;
172		200
173	=cut	201	=cut
174		202
175	sub async(&@) {	203	sub async(&@) {
176	my $pid = new Coro @_;	204	my $coro = new Coro @_;
177	$manager->ready; # this ensures that the stack is cloned from the manager
178	$pid->ready;	205	$coro->ready;
179	$pid;	206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		230	terminate }> once per second or so to slowly replenish the pool.
		231
		232	=cut
		233
		234	our $POOL_SIZE = 8;
		235	our $MAX_POOL_RSS = 64 * 1024;
		236	our @pool;
		237
		238	sub pool_handler {
		239	while () {
		240	$current->{desc} = "[async_pool]";
		241
		242	eval {
		243	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		244	$cb->(@arg);
		245	};
		246	warn $@ if $@;
		247
		248	last if @pool >= $POOL_SIZE \|\| $current->rss >= $MAX_POOL_RSS;
		249
		250	push @pool, $current;
		251	$current->{desc} = "[async_pool idle]";
		252	$current->save (Coro::State::SAVE_DEF);
		253	$current->prio (0);
		254	schedule;
		255	}
		256	}
		257
		258	sub async_pool(&@) {
		259	# this is also inlined into the unlock_scheduler
		260	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		261
		262	$coro->{_invoke} = [@_];
		263	$coro->ready;
		264
		265	$coro
180	}	266	}
181		267
182	=item schedule	268	=item schedule
183		269
184	Calls the scheduler. Please note that the current process will not be put	270	Calls the scheduler. Please note that the current coroutine will not be put
185	into the ready queue, so calling this function usually means you will	271	into the ready queue, so calling this function usually means you will
186	never be called again.	272	never be called again unless something else (e.g. an event handler) calls
		273	ready.
187		274
188	=cut	275	The canonical way to wait on external events is this:
		276
		277	{
		278	# remember current coroutine
		279	my $current = $Coro::current;
		280
		281	# register a hypothetical event handler
		282	on_event_invoke sub {
		283	# wake up sleeping coroutine
		284	$current->ready;
		285	undef $current;
		286	};
		287
		288	# call schedule until event occurred.
		289	# in case we are woken up for other reasons
		290	# (current still defined), loop.
		291	Coro::schedule while $current;
		292	}
189		293
190	=item cede	294	=item cede
191		295
192	"Cede" to other processes. This function puts the current process into the	296	"Cede" to other coroutines. This function puts the current coroutine into the
193	ready queue and calls C<schedule>, which has the effect of giving up the	297	ready queue and calls C<schedule>, which has the effect of giving up the
194	current "timeslice" to other coroutines of the same or higher priority.	298	current "timeslice" to other coroutines of the same or higher priority.
195		299
196	=cut	300	Returns true if at least one coroutine switch has happened.
		301
		302	=item Coro::cede_notself
		303
		304	Works like cede, but is not exported by default and will cede to any
		305	coroutine, regardless of priority, once.
		306
		307	Returns true if at least one coroutine switch has happened.
197		308
198	=item terminate [arg...]	309	=item terminate [arg...]
199		310
200	Terminates the current process with the given status values (see L<cancel>).	311	Terminates the current coroutine with the given status values (see L<cancel>).
201		312
202	=cut	313	=cut
203		314
204	sub terminate {	315	sub terminate {
205	$current->cancel (@_);	316	$current->cancel (@_);
…		…
207		318
208	=back	319	=back
209		320
210	# dynamic methods	321	# dynamic methods
211		322
212	=head2 PROCESS METHODS	323	=head2 COROUTINE METHODS
213		324
214	These are the methods you can call on process objects.	325	These are the methods you can call on coroutine objects.
215		326
216	=over 4	327	=over 4
217		328
218	=item new Coro \&sub [, @args...]	329	=item new Coro \&sub [, @args...]
219		330
220	Create a new process and return it. When the sub returns the process	331	Create a new coroutine and return it. When the sub returns the coroutine
221	automatically terminates as if C<terminate> with the returned values were	332	automatically terminates as if C<terminate> with the returned values were
222	called. To make the process run you must first put it into the ready queue	333	called. To make the coroutine run you must first put it into the ready queue
223	by calling the ready method.	334	by calling the ready method.
224		335
225	=cut	336	See C<async> for additional discussion.
226		337
		338	=cut
		339
227	sub _newcoro {	340	sub _run_coro {
228	terminate &{+shift};	341	terminate &{+shift};
229	}	342	}
230		343
231	sub new {	344	sub new {
232	my $class = shift;	345	my $class = shift;
233	bless {
234	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
235	}, $class;
236	}
237		346
238	=item $process->ready	347	$class->SUPER::new (\&_run_coro, @_)
		348	}
239		349
240	Put the given process into the ready queue.	350	=item $success = $coroutine->ready
241		351
242	=cut	352	Put the given coroutine into the ready queue (according to it's priority)
		353	and return true. If the coroutine is already in the ready queue, do nothing
		354	and return false.
243		355
		356	=item $is_ready = $coroutine->is_ready
		357
		358	Return wether the coroutine is currently the ready queue or not,
		359
244	=item $process->cancel (arg...)	360	=item $coroutine->cancel (arg...)
245		361
246	Temrinates the given process and makes it return the given arguments as	362	Terminates the given coroutine and makes it return the given arguments as
247	status (default: the empty list).	363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
248		365
249	=cut	366	=cut
250		367
251	sub cancel {	368	sub cancel {
252	my $self = shift;	369	my $self = shift;
253	$self->{status} = [@_];	370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
254	push @destroy, $self;	373	push @destroy, $self;
255	$manager->ready;	374	$manager->ready;
256	&schedule if $current == $self;	375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
257	}	379	}
258		380
259	=item $process->join	381	=item $coroutine->join
260		382
261	Wait until the coroutine terminates and return any values given to the	383	Wait until the coroutine terminates and return any values given to the
262	C<terminate> or C<cancel> functions. C<join> can be called multiple times	384	C<terminate> or C<cancel> functions. C<join> can be called multiple times
263	from multiple processes.	385	from multiple coroutine.
264		386
265	=cut	387	=cut
266		388
267	sub join {	389	sub join {
268	my $self = shift;	390	my $self = shift;
		391
269	unless ($self->{status}) {	392	unless ($self->{status}) {
270	push @{$self->{join}}, $current;	393	my $current = $current;
271	&schedule;	394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
272	}	401	}
		402
273	wantarray ? @{$self->{status}} : $self->{status}[0];	403	wantarray ? @{$self->{status}} : $self->{status}[0];
274	}	404	}
275		405
		406	=item $coroutine->on_destroy (\&cb)
		407
		408	Registers a callback that is called when this coroutine gets destroyed,
		409	but before it is joined. The callback gets passed the terminate arguments,
		410	if any.
		411
		412	=cut
		413
		414	sub on_destroy {
		415	my ($self, $cb) = @_;
		416
		417	push @{ $self->{destroy_cb} }, $cb;
		418	}
		419
276	=item $oldprio = $process->prio($newprio)	420	=item $oldprio = $coroutine->prio ($newprio)
277		421
278	Sets (or gets, if the argument is missing) the priority of the	422	Sets (or gets, if the argument is missing) the priority of the
279	process. Higher priority processes get run before lower priority	423	coroutine. Higher priority coroutines get run before lower priority
280	processes. Priorities are small signed integers (currently -4 .. +3),	424	coroutines. Priorities are small signed integers (currently -4 .. +3),
281	that you can refer to using PRIO_xxx constants (use the import tag :prio	425	that you can refer to using PRIO_xxx constants (use the import tag :prio
282	to get then):	426	to get then):
283		427
284	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	428	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
285	3 > 1 > 0 > -1 > -3 > -4	429	3 > 1 > 0 > -1 > -3 > -4
…		…
288	current->prio(PRIO_HIGH);	432	current->prio(PRIO_HIGH);
289		433
290	The idle coroutine ($Coro::idle) always has a lower priority than any	434	The idle coroutine ($Coro::idle) always has a lower priority than any
291	existing coroutine.	435	existing coroutine.
292		436
293	Changing the priority of the current process will take effect immediately,	437	Changing the priority of the current coroutine will take effect immediately,
294	but changing the priority of processes in the ready queue (but not	438	but changing the priority of coroutines in the ready queue (but not
295	running) will only take effect after the next schedule (of that	439	running) will only take effect after the next schedule (of that
296	process). This is a bug that will be fixed in some future version.	440	coroutine). This is a bug that will be fixed in some future version.
297		441
298	=cut
299
300	sub prio {
301	my $old = $_[0]{prio};
302	$_[0]{prio} = $_[1] if @_ > 1;
303	$old;
304	}
305
306	=item $newprio = $process->nice($change)	442	=item $newprio = $coroutine->nice ($change)
307		443
308	Similar to C<prio>, but subtract the given value from the priority (i.e.	444	Similar to C<prio>, but subtract the given value from the priority (i.e.
309	higher values mean lower priority, just as in unix).	445	higher values mean lower priority, just as in unix).
310		446
311	=cut
312
313	sub nice {
314	$_[0]{prio} -= $_[1];
315	}
316
317	=item $olddesc = $process->desc($newdesc)	447	=item $olddesc = $coroutine->desc ($newdesc)
318		448
319	Sets (or gets in case the argument is missing) the description for this	449	Sets (or gets in case the argument is missing) the description for this
320	process. This is just a free-form string you can associate with a process.	450	coroutine. This is just a free-form string you can associate with a coroutine.
321		451
322	=cut	452	=cut
323		453
324	sub desc {	454	sub desc {
325	my $old = $_[0]{desc};	455	my $old = $_[0]{desc};
…		…
327	$old;	457	$old;
328	}	458	}
329		459
330	=back	460	=back
331		461
		462	=head2 GLOBAL FUNCTIONS
		463
		464	=over 4
		465
		466	=item Coro::nready
		467
		468	Returns the number of coroutines that are currently in the ready state,
		469	i.e. that can be switched to. The value C<0> means that the only runnable
		470	coroutine is the currently running one, so C<cede> would have no effect,
		471	and C<schedule> would cause a deadlock unless there is an idle handler
		472	that wakes up some coroutines.
		473
		474	=item my $guard = Coro::guard { ... }
		475
		476	This creates and returns a guard object. Nothing happens until the object
		477	gets destroyed, in which case the codeblock given as argument will be
		478	executed. This is useful to free locks or other resources in case of a
		479	runtime error or when the coroutine gets canceled, as in both cases the
		480	guard block will be executed. The guard object supports only one method,
		481	C<< ->cancel >>, which will keep the codeblock from being executed.
		482
		483	Example: set some flag and clear it again when the coroutine gets canceled
		484	or the function returns:
		485
		486	sub do_something {
		487	my $guard = Coro::guard { $busy = 0 };
		488	$busy = 1;
		489
		490	# do something that requires $busy to be true
		491	}
		492
		493	=cut
		494
		495	sub guard(&) {
		496	bless \(my $cb = $_[0]), "Coro::guard"
		497	}
		498
		499	sub Coro::guard::cancel {
		500	${$_[0]} = sub { };
		501	}
		502
		503	sub Coro::guard::DESTROY {
		504	${$_[0]}->();
		505	}
		506
		507
		508	=item unblock_sub { ... }
		509
		510	This utility function takes a BLOCK or code reference and "unblocks" it,
		511	returning the new coderef. This means that the new coderef will return
		512	immediately without blocking, returning nothing, while the original code
		513	ref will be called (with parameters) from within its own coroutine.
		514
		515	The reason this function exists is that many event libraries (such as the
		516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		517	of thread-safety). This means you must not block within event callbacks,
		518	otherwise you might suffer from crashes or worse.
		519
		520	This function allows your callbacks to block by executing them in another
		521	coroutine where it is safe to block. One example where blocking is handy
		522	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		523	disk.
		524
		525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		526	creating event callbacks that want to block.
		527
		528	=cut
		529
		530	our @unblock_queue;
		531
		532	# we create a special coro because we want to cede,
		533	# to reduce pressure on the coro pool (because most callbacks
		534	# return immediately and can be reused) and because we cannot cede
		535	# inside an event callback.
		536	our $unblock_scheduler = async {
		537	$current->desc ("[unblock_sub scheduler]");
		538	while () {
		539	while (my $cb = pop @unblock_queue) {
		540	# this is an inlined copy of async_pool
		541	my $coro = (pop @pool or new Coro \&pool_handler);
		542
		543	$coro->{_invoke} = $cb;
		544	$coro->ready;
		545	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		546	}
		547	schedule; # sleep well
		548	}
		549	};
		550
		551	sub unblock_sub(&) {
		552	my $cb = shift;
		553
		554	sub {
		555	unshift @unblock_queue, [$cb, @_];
		556	$unblock_scheduler->ready;
		557	}
		558	}
		559
		560	=back
		561
332	=cut	562	=cut
333		563
334	1;	564	1;
335		565
336	=head1 BUGS/LIMITATIONS	566	=head1 BUGS/LIMITATIONS
337		567
338	- you must make very sure that no coro is still active on global	568	- you must make very sure that no coro is still active on global
339	destruction. very bad things might happen otherwise (usually segfaults).	569	destruction. very bad things might happen otherwise (usually segfaults).
340		570
341	- this module is not thread-safe. You should only ever use this module	571	- this module is not thread-safe. You should only ever use this module
342	from the same thread (this requirement might be losened in the future	572	from the same thread (this requirement might be loosened in the future
343	to allow per-thread schedulers, but Coro::State does not yet allow	573	to allow per-thread schedulers, but Coro::State does not yet allow
344	this).	574	this).
345		575
346	=head1 SEE ALSO	576	=head1 SEE ALSO
347		577

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Comparing Coro/Coro.pm (file contents): Revision 1.78 by root, Wed Nov 1 01:21:21 2006 UTC vs. Revision 1.130 by root, Thu Sep 20 12:02:25 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.78 by root, Wed Nov 1 01:21:21 2006 UTC vs.
Revision 1.130 by root, Thu Sep 20 12:02:25 2007 UTC