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

Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 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
…		…
41		50
42	our $idle; # idle handler	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 = '3.0';	55	our $VERSION = '3.8';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
99		108
100	The current coroutine (the last coroutine switched to). The initial value	109	The current coroutine (the last coroutine switched to). The initial value
101	is C<$main> (of course).	110	is C<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
		118	$main->{desc} = "[main::]";
		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
112	}	122	if $current;
113		123
114	$current = $main;	124	_set_current $main;
115		125
116	sub current() { $current }	126	sub current() { $current }
117		127
118	=item $idle	128	=item $idle
119		129
…		…
129	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively.
130		140
131	=cut	141	=cut
132		142
133	$idle = sub {	143	$idle = sub {
134	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
135	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
136	};	146	};
		147
		148	sub _cancel {
		149	my ($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 $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	sub _do_trace_sub {
		161	&{$current->{_trace_sub_cb}}
		162	}
		163
		164	sub _do_trace_line {
		165	&{$current->{_trace_line_cb}}
		166	}
137		167
138	# this coroutine is necessary because a coroutine	168	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	169	# cannot destroy itself.
140	my @destroy;	170	my @destroy;
		171	my $manager;
		172
141	my $manager; $manager = new Coro sub {	173	$manager = new Coro sub {
142	while () {	174	while () {
143	# by overwriting the state object with the manager we destroy it	175	(shift @destroy)->_cancel
144	# while still being able to schedule this coroutine (in case it has
145	# been readied multiple times. this is harmless since the manager
146	# can be called as many times as neccessary and will always
147	# remove itself from the runqueue
148	while (@destroy) {	176	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		177
153	# the next line destroys the coro state, but keeps the
154	# process itself intact (we basically make it a zombie
155	# process that always runs the manager thread, so it's possible
156	# to transfer() to this process).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	178	&schedule;
160	}	179	}
161	};	180	};
		181	$manager->desc ("[coro manager]");
		182	$manager->prio (PRIO_MAX);
162		183
163	# static methods. not really.	184	# static methods. not really.
164		185
165	=back	186	=back
166		187
167	=head2 STATIC METHODS	188	=head2 STATIC METHODS
168		189
169	Static methods are actually functions that operate on the current process only.	190	Static methods are actually functions that operate on the current coroutine only.
170		191
171	=over 4	192	=over 4
172		193
173	=item async { ... } [@args...]	194	=item async { ... } [@args...]
174		195
175	Create a new asynchronous process and return it's process object	196	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new process is automatically	197	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	198	terminated.
178		199
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	200	Calling C<exit> in a coroutine will do the same as calling exit outside
180		201	the coroutine. Likewise, when the coroutine dies, the program will exit,
181	When the coroutine dies, the program will exit, just as in the main	202	just as it would in the main program.
182	program.
183		203
184	# create a new coroutine that just prints its arguments	204	# create a new coroutine that just prints its arguments
185	async {	205	async {
186	print "@_\n";	206	print "@_\n";
187	} 1,2,3,4;	207	} 1,2,3,4;
188		208
189	=cut	209	=cut
190		210
191	sub async(&@) {	211	sub async(&@) {
192	my $pid = new Coro @_;	212	my $coro = new Coro @_;
193	$pid->ready;	213	$coro->ready;
194	$pid	214	$coro
		215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join (although you are allowed to), and you get a coroutine
		221	that might have executed other code already (which can be good or bad :).
		222
		223	Also, the block is executed in an C<eval> context and a warning will be
		224	issued in case of an exception instead of terminating the program, as
		225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		226	will not work in the expected way, unless you call terminate or cancel,
		227	which somehow defeats the purpose of pooling.
		228
		229	The priority will be reset to C<0> after each job, otherwise the coroutine
		230	will be re-used "as-is".
		231
		232	The pool size is limited to 8 idle coroutines (this can be adjusted by
		233	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		234	required.
		235
		236	If you are concerned about pooled coroutines growing a lot because a
		237	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		238	{ terminate }> once per second or so to slowly replenish the pool. In
		239	addition to that, when the stacks used by a handler grows larger than 16kb
		240	(adjustable with $Coro::POOL_RSS) it will also exit.
		241
		242	=cut
		243
		244	our $POOL_SIZE = 8;
		245	our $POOL_RSS = 16 * 1024;
		246	our @async_pool;
		247
		248	sub pool_handler {
		249	my $cb;
		250
		251	while () {
		252	eval {
		253	while () {
		254	_pool_1 $cb;
		255	&$cb;
		256	_pool_2 $cb;
		257	&schedule;
		258	}
		259	};
		260
		261	last if $@ eq "\3terminate\2\n";
		262	warn $@ if $@;
		263	}
		264	}
		265
		266	sub async_pool(&@) {
		267	# this is also inlined into the unlock_scheduler
		268	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		269
		270	$coro->{_invoke} = [@_];
		271	$coro->ready;
		272
		273	$coro
195	}	274	}
196		275
197	=item schedule	276	=item schedule
198		277
199	Calls the scheduler. Please note that the current process will not be put	278	Calls the scheduler. Please note that the current coroutine will not be put
200	into the ready queue, so calling this function usually means you will	279	into the ready queue, so calling this function usually means you will
201	never be called again unless something else (e.g. an event handler) calls	280	never be called again unless something else (e.g. an event handler) calls
202	ready.	281	ready.
203		282
204	The canonical way to wait on external events is this:	283	The canonical way to wait on external events is this:
205		284
206	{	285	{
207	# remember current process	286	# remember current coroutine
208	my $current = $Coro::current;	287	my $current = $Coro::current;
209		288
210	# register a hypothetical event handler	289	# register a hypothetical event handler
211	on_event_invoke sub {	290	on_event_invoke sub {
212	# wake up sleeping coroutine	291	# wake up sleeping coroutine
213	$current->ready;	292	$current->ready;
214	undef $current;	293	undef $current;
215	};	294	};
216		295
217	# call schedule until event occured.	296	# call schedule until event occurred.
218	# in case we are woken up for other reasons	297	# in case we are woken up for other reasons
219	# (current still defined), loop.	298	# (current still defined), loop.
220	Coro::schedule while $current;	299	Coro::schedule while $current;
221	}	300	}
222		301
223	=cut
224
225	=item cede	302	=item cede
226		303
227	"Cede" to other processes. This function puts the current process into the	304	"Cede" to other coroutines. This function puts the current coroutine into the
228	ready queue and calls C<schedule>, which has the effect of giving up the	305	ready queue and calls C<schedule>, which has the effect of giving up the
229	current "timeslice" to other coroutines of the same or higher priority.	306	current "timeslice" to other coroutines of the same or higher priority.
230		307
231	=cut	308	Returns true if at least one coroutine switch has happened.
		309
		310	=item Coro::cede_notself
		311
		312	Works like cede, but is not exported by default and will cede to any
		313	coroutine, regardless of priority, once.
		314
		315	Returns true if at least one coroutine switch has happened.
232		316
233	=item terminate [arg...]	317	=item terminate [arg...]
234		318
235	Terminates the current process with the given status values (see L<cancel>).	319	Terminates the current coroutine with the given status values (see L<cancel>).
236		320
237	=cut	321	=cut
238		322
239	sub terminate {	323	sub terminate {
240	$current->cancel (@_);	324	$current->cancel (@_);
…		…
242		326
243	=back	327	=back
244		328
245	# dynamic methods	329	# dynamic methods
246		330
247	=head2 PROCESS METHODS	331	=head2 COROUTINE METHODS
248		332
249	These are the methods you can call on process objects.	333	These are the methods you can call on coroutine objects.
250		334
251	=over 4	335	=over 4
252		336
253	=item new Coro \&sub [, @args...]	337	=item new Coro \&sub [, @args...]
254		338
255	Create a new process and return it. When the sub returns the process	339	Create a new coroutine and return it. When the sub returns the coroutine
256	automatically terminates as if C<terminate> with the returned values were	340	automatically terminates as if C<terminate> with the returned values were
257	called. To make the process run you must first put it into the ready queue	341	called. To make the coroutine run you must first put it into the ready queue
258	by calling the ready method.	342	by calling the ready method.
259		343
260	Calling C<exit> in a coroutine will not work correctly, so do not do that.	344	See C<async> for additional discussion.
261		345
262	=cut	346	=cut
263		347
264	sub _new_coro {	348	sub _run_coro {
265	terminate &{+shift};	349	terminate &{+shift};
266	}	350	}
267		351
268	sub new {	352	sub new {
269	my $class = shift;	353	my $class = shift;
270		354
271	$class->SUPER::new (\&_new_coro, @_)	355	$class->SUPER::new (\&_run_coro, @_)
272	}	356	}
273		357
274	=item $success = $process->ready	358	=item $success = $coroutine->ready
275		359
276	Put the given process into the ready queue (according to it's priority)	360	Put the given coroutine into the ready queue (according to it's priority)
277	and return true. If the process is already in the ready queue, do nothing	361	and return true. If the coroutine is already in the ready queue, do nothing
278	and return false.	362	and return false.
279		363
280	=item $is_ready = $process->is_ready	364	=item $is_ready = $coroutine->is_ready
281		365
282	Return wether the process is currently the ready queue or not,	366	Return wether the coroutine is currently the ready queue or not,
283		367
284	=item $process->cancel (arg...)	368	=item $coroutine->cancel (arg...)
285		369
286	Terminates the given process and makes it return the given arguments as	370	Terminates the given coroutine and makes it return the given arguments as
287	status (default: the empty list).	371	status (default: the empty list). Never returns if the coroutine is the
		372	current coroutine.
288		373
289	=cut	374	=cut
290		375
291	sub cancel {	376	sub cancel {
292	my $self = shift;	377	my $self = shift;
293	$self->{status} = [@_];	378	$self->{status} = [@_];
		379
		380	if ($current == $self) {
294	push @destroy, $self;	381	push @destroy, $self;
295	$manager->ready;	382	$manager->ready;
296	&schedule if $current == $self;	383	&schedule while 1;
		384	} else {
		385	$self->_cancel;
		386	}
297	}	387	}
298		388
299	=item $process->join	389	=item $coroutine->join
300		390
301	Wait until the coroutine terminates and return any values given to the	391	Wait until the coroutine terminates and return any values given to the
302	C<terminate> or C<cancel> functions. C<join> can be called multiple times	392	C<terminate> or C<cancel> functions. C<join> can be called multiple times
303	from multiple processes.	393	from multiple coroutine.
304		394
305	=cut	395	=cut
306		396
307	sub join {	397	sub join {
308	my $self = shift;	398	my $self = shift;
		399
309	unless ($self->{status}) {	400	unless ($self->{status}) {
310	push @{$self->{join}}, $current;	401	my $current = $current;
311	&schedule;	402
		403	push @{$self->{destroy_cb}}, sub {
		404	$current->ready;
		405	undef $current;
		406	};
		407
		408	&schedule while $current;
312	}	409	}
		410
313	wantarray ? @{$self->{status}} : $self->{status}[0];	411	wantarray ? @{$self->{status}} : $self->{status}[0];
314	}	412	}
315		413
		414	=item $coroutine->on_destroy (\&cb)
		415
		416	Registers a callback that is called when this coroutine gets destroyed,
		417	but before it is joined. The callback gets passed the terminate arguments,
		418	if any.
		419
		420	=cut
		421
		422	sub on_destroy {
		423	my ($self, $cb) = @_;
		424
		425	push @{ $self->{destroy_cb} }, $cb;
		426	}
		427
316	=item $oldprio = $process->prio ($newprio)	428	=item $oldprio = $coroutine->prio ($newprio)
317		429
318	Sets (or gets, if the argument is missing) the priority of the	430	Sets (or gets, if the argument is missing) the priority of the
319	process. Higher priority processes get run before lower priority	431	coroutine. Higher priority coroutines get run before lower priority
320	processes. Priorities are small signed integers (currently -4 .. +3),	432	coroutines. Priorities are small signed integers (currently -4 .. +3),
321	that you can refer to using PRIO_xxx constants (use the import tag :prio	433	that you can refer to using PRIO_xxx constants (use the import tag :prio
322	to get then):	434	to get then):
323		435
324	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	436	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
325	3 > 1 > 0 > -1 > -3 > -4	437	3 > 1 > 0 > -1 > -3 > -4
…		…
328	current->prio(PRIO_HIGH);	440	current->prio(PRIO_HIGH);
329		441
330	The idle coroutine ($Coro::idle) always has a lower priority than any	442	The idle coroutine ($Coro::idle) always has a lower priority than any
331	existing coroutine.	443	existing coroutine.
332		444
333	Changing the priority of the current process will take effect immediately,	445	Changing the priority of the current coroutine will take effect immediately,
334	but changing the priority of processes in the ready queue (but not	446	but changing the priority of coroutines in the ready queue (but not
335	running) will only take effect after the next schedule (of that	447	running) will only take effect after the next schedule (of that
336	process). This is a bug that will be fixed in some future version.	448	coroutine). This is a bug that will be fixed in some future version.
337		449
338	=item $newprio = $process->nice ($change)	450	=item $newprio = $coroutine->nice ($change)
339		451
340	Similar to C<prio>, but subtract the given value from the priority (i.e.	452	Similar to C<prio>, but subtract the given value from the priority (i.e.
341	higher values mean lower priority, just as in unix).	453	higher values mean lower priority, just as in unix).
342		454
343	=item $olddesc = $process->desc ($newdesc)	455	=item $olddesc = $coroutine->desc ($newdesc)
344		456
345	Sets (or gets in case the argument is missing) the description for this	457	Sets (or gets in case the argument is missing) the description for this
346	process. This is just a free-form string you can associate with a process.	458	coroutine. This is just a free-form string you can associate with a coroutine.
347		459
348	=cut	460	=cut
349		461
350	sub desc {	462	sub desc {
351	my $old = $_[0]{desc};	463	my $old = $_[0]{desc};
…		…
353	$old;	465	$old;
354	}	466	}
355		467
356	=back	468	=back
357		469
		470	=head2 GLOBAL FUNCTIONS
		471
		472	=over 4
		473
		474	=item Coro::nready
		475
		476	Returns the number of coroutines that are currently in the ready state,
		477	i.e. that can be switched to. The value C<0> means that the only runnable
		478	coroutine is the currently running one, so C<cede> would have no effect,
		479	and C<schedule> would cause a deadlock unless there is an idle handler
		480	that wakes up some coroutines.
		481
		482	=item my $guard = Coro::guard { ... }
		483
		484	This creates and returns a guard object. Nothing happens until the object
		485	gets destroyed, in which case the codeblock given as argument will be
		486	executed. This is useful to free locks or other resources in case of a
		487	runtime error or when the coroutine gets canceled, as in both cases the
		488	guard block will be executed. The guard object supports only one method,
		489	C<< ->cancel >>, which will keep the codeblock from being executed.
		490
		491	Example: set some flag and clear it again when the coroutine gets canceled
		492	or the function returns:
		493
		494	sub do_something {
		495	my $guard = Coro::guard { $busy = 0 };
		496	$busy = 1;
		497
		498	# do something that requires $busy to be true
		499	}
		500
		501	=cut
		502
		503	sub guard(&) {
		504	bless \(my $cb = $_[0]), "Coro::guard"
		505	}
		506
		507	sub Coro::guard::cancel {
		508	${$_[0]} = sub { };
		509	}
		510
		511	sub Coro::guard::DESTROY {
		512	${$_[0]}->();
		513	}
		514
		515
		516	=item unblock_sub { ... }
		517
		518	This utility function takes a BLOCK or code reference and "unblocks" it,
		519	returning the new coderef. This means that the new coderef will return
		520	immediately without blocking, returning nothing, while the original code
		521	ref will be called (with parameters) from within its own coroutine.
		522
		523	The reason this function exists is that many event libraries (such as the
		524	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		525	of thread-safety). This means you must not block within event callbacks,
		526	otherwise you might suffer from crashes or worse.
		527
		528	This function allows your callbacks to block by executing them in another
		529	coroutine where it is safe to block. One example where blocking is handy
		530	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		531	disk.
		532
		533	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		534	creating event callbacks that want to block.
		535
		536	=cut
		537
		538	our @unblock_queue;
		539
		540	# we create a special coro because we want to cede,
		541	# to reduce pressure on the coro pool (because most callbacks
		542	# return immediately and can be reused) and because we cannot cede
		543	# inside an event callback.
		544	our $unblock_scheduler = new Coro sub {
		545	while () {
		546	while (my $cb = pop @unblock_queue) {
		547	# this is an inlined copy of async_pool
		548	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		549
		550	$coro->{_invoke} = $cb;
		551	$coro->ready;
		552	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		553	}
		554	schedule; # sleep well
		555	}
		556	};
		557	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		558
		559	sub unblock_sub(&) {
		560	my $cb = shift;
		561
		562	sub {
		563	unshift @unblock_queue, [$cb, @_];
		564	$unblock_scheduler->ready;
		565	}
		566	}
		567
		568	=back
		569
358	=cut	570	=cut
359		571
360	1;	572	1;
361		573
362	=head1 BUGS/LIMITATIONS	574	=head1 BUGS/LIMITATIONS
363		575
364	- you must make very sure that no coro is still active on global	576	- you must make very sure that no coro is still active on global
365	destruction. very bad things might happen otherwise (usually segfaults).	577	destruction. very bad things might happen otherwise (usually segfaults).
366		578
367	- this module is not thread-safe. You should only ever use this module	579	- this module is not thread-safe. You should only ever use this module
368	from the same thread (this requirement might be losened in the future	580	from the same thread (this requirement might be loosened in the future
369	to allow per-thread schedulers, but Coro::State does not yet allow	581	to allow per-thread schedulers, but Coro::State does not yet allow
370	this).	582	this).
371		583
372	=head1 SEE ALSO	584	=head1 SEE ALSO
373		585

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Comparing Coro/Coro.pm (file contents): Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs. Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC