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

Comparing Coro/Coro.pm (file contents):
Revision 1.93 by root, Fri Dec 1 19:41:06 2006 UTC vs.
Revision 1.132 by root, Thu Sep 20 22:53:23 2007 UTC

…		…
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 $VERSION = '3.7';
47		56
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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 $init;
57		66
…		…
99		108
100	The current coroutine (the last coroutine switched to). The initial value	109	The current coroutine (the last coroutine switched to). The initial value
101	is C<$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
		117
		118	$main->{desc} = "[main::]";
108		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	$main->{specific} = $current->{specific}	121	$main->{specific} = $current->{specific}
111	if $current;	122	if $current;
112		123
…		…
128	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively.
129		140
130	=cut	141	=cut
131		142
132	$idle = sub {	143	$idle = sub {
133	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
134	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
135	};	146	};
		147
		148	sub _cancel {
		149	my ($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	}
136		159
137	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
138	# cannot destroy itself.	161	# cannot destroy itself.
139	my @destroy;	162	my @destroy;
		163	my $manager;
		164
140	my $manager; $manager = new Coro sub {	165	$manager = new Coro sub {
141	while () {	166	while () {
142	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
143	# while still being able to schedule this coroutine (in case it has
144	# been readied multiple times. this is harmless since the manager
145	# can be called as many times as neccessary and will always
146	# remove itself from the runqueue
147	while (@destroy) {	168	while @destroy;
148	my $coro = pop @destroy;
149	$coro->{status} \|\|= [];
150	$_->ready for @{delete $coro->{join} \|\| []};
151		169
152	# the next line destroys the coro state, but keeps the
153	# coroutine itself intact (we basically make it a zombie
154	# coroutine that always runs the manager thread, so it's possible
155	# to transfer() to this coroutine).
156	$coro->_clone_state_from ($manager);
157	}
158	&schedule;	170	&schedule;
159	}	171	}
160	};	172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
161		175
162	# static methods. not really.	176	# static methods. not really.
163		177
164	=back	178	=back
165		179
…		…
173		187
174	Create a new asynchronous coroutine and return it's coroutine object	188	Create a new asynchronous coroutine and return it's coroutine object
175	(usually unused). When the sub returns the new coroutine is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
176	terminated.	190	terminated.
177		191
178	Calling C<exit> in a coroutine will not work correctly, so do not do that.	192	Calling C<exit> in a coroutine will do the same as calling exit outside
179		193	the coroutine. Likewise, when the coroutine dies, the program will exit,
180	When the coroutine dies, the program will exit, just as in the main	194	just as it would in the main program.
181	program.
182		195
183	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
184	async {	197	async {
185	print "@_\n";	198	print "@_\n";
186	} 1,2,3,4;	199	} 1,2,3,4;
187		200
188	=cut	201	=cut
189		202
190	sub async(&@) {	203	sub async(&@) {
191	my $pid = new Coro @_;	204	my $coro = new Coro @_;
192	$pid->ready;	205	$coro->ready;
193	$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
194	}	266	}
195		267
196	=item schedule	268	=item schedule
197		269
198	Calls the scheduler. Please note that the current coroutine will not be put	270	Calls the scheduler. Please note that the current coroutine will not be put
…		…
211	# wake up sleeping coroutine	283	# wake up sleeping coroutine
212	$current->ready;	284	$current->ready;
213	undef $current;	285	undef $current;
214	};	286	};
215		287
216	# call schedule until event occured.	288	# call schedule until event occurred.
217	# in case we are woken up for other reasons	289	# in case we are woken up for other reasons
218	# (current still defined), loop.	290	# (current still defined), loop.
219	Coro::schedule while $current;	291	Coro::schedule while $current;
220	}	292	}
221		293
222	=item cede	294	=item cede
223		295
224	"Cede" to other coroutines. This function puts the current coroutine into the	296	"Cede" to other coroutines. This function puts the current coroutine into the
225	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
226	current "timeslice" to other coroutines of the same or higher priority.	298	current "timeslice" to other coroutines of the same or higher priority.
		299
		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.
227		308
228	=item terminate [arg...]	309	=item terminate [arg...]
229		310
230	Terminates the current coroutine with the given status values (see L<cancel>).	311	Terminates the current coroutine with the given status values (see L<cancel>).
231		312
…		…
250	Create a new coroutine and return it. When the sub returns the coroutine	331	Create a new coroutine and return it. When the sub returns the coroutine
251	automatically terminates as if C<terminate> with the returned values were	332	automatically terminates as if C<terminate> with the returned values were
252	called. To make the coroutine 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
253	by calling the ready method.	334	by calling the ready method.
254		335
255	Calling C<exit> in a coroutine will not work correctly, so do not do that.	336	See C<async> for additional discussion.
256		337
257	=cut	338	=cut
258		339
259	sub _new_coro {	340	sub _run_coro {
260	terminate &{+shift};	341	terminate &{+shift};
261	}	342	}
262		343
263	sub new {	344	sub new {
264	my $class = shift;	345	my $class = shift;
265		346
266	$class->SUPER::new (\&_new_coro, @_)	347	$class->SUPER::new (\&_run_coro, @_)
267	}	348	}
268		349
269	=item $success = $coroutine->ready	350	=item $success = $coroutine->ready
270		351
271	Put the given coroutine into the ready queue (according to it's priority)	352	Put the given coroutine into the ready queue (according to it's priority)
…		…
277	Return wether the coroutine is currently the ready queue or not,	358	Return wether the coroutine is currently the ready queue or not,
278		359
279	=item $coroutine->cancel (arg...)	360	=item $coroutine->cancel (arg...)
280		361
281	Terminates the given coroutine and makes it return the given arguments as	362	Terminates the given coroutine and makes it return the given arguments as
282	status (default: the empty list).	363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
283		365
284	=cut	366	=cut
285		367
286	sub cancel {	368	sub cancel {
287	my $self = shift;	369	my $self = shift;
288	$self->{status} = [@_];	370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
289	push @destroy, $self;	373	push @destroy, $self;
290	$manager->ready;	374	$manager->ready;
291	&schedule if $current == $self;	375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
292	}	379	}
293		380
294	=item $coroutine->join	381	=item $coroutine->join
295		382
296	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
…		…
299		386
300	=cut	387	=cut
301		388
302	sub join {	389	sub join {
303	my $self = shift;	390	my $self = shift;
		391
304	unless ($self->{status}) {	392	unless ($self->{status}) {
305	push @{$self->{join}}, $current;	393	my $current = $current;
306	&schedule;	394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
307	}	401	}
		402
308	wantarray ? @{$self->{status}} : $self->{status}[0];	403	wantarray ? @{$self->{status}} : $self->{status}[0];
		404	}
		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;
309	}	418	}
310		419
311	=item $oldprio = $coroutine->prio ($newprio)	420	=item $oldprio = $coroutine->prio ($newprio)
312		421
313	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
…		…
348	$old;	457	$old;
349	}	458	}
350		459
351	=back	460	=back
352		461
353	=head2 UTILITY FUNCTIONS	462	=head2 GLOBAL FUNCTIONS
354		463
355	=over 4	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
356		507
357	=item unblock_sub { ... }	508	=item unblock_sub { ... }
358		509
359	This utility function takes a BLOCK or code reference and "unblocks" it,	510	This utility function takes a BLOCK or code reference and "unblocks" it,
360	returning the new coderef. This means that the new coderef will return	511	returning the new coderef. This means that the new coderef will return
361	immediately without blocking, returning nothing, while the original code	512	immediately without blocking, returning nothing, while the original code
362	ref will be called (with parameters) from within its own coroutine.	513	ref will be called (with parameters) from within its own coroutine.
363		514
364	The reason this fucntion exists is that many event libraries (such as the	515	The reason this function exists is that many event libraries (such as the
365	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
366	of thread-safety). This means you must not block within event callbacks,	517	of thread-safety). This means you must not block within event callbacks,
367	otherwise you might suffer from crashes or worse.	518	otherwise you might suffer from crashes or worse.
368		519
369	This function allows your callbacks to block by executing them in another	520	This function allows your callbacks to block by executing them in another
…		…
374	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
375	creating event callbacks that want to block.	526	creating event callbacks that want to block.
376		527
377	=cut	528	=cut
378		529
379	our @unblock_pool;
380	our @unblock_queue;	530	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		531
383	sub unblock_handler_ {	532	# we create a special coro because we want to cede,
384	while () {	533	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	534	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	535	# inside an event callback.
387
388	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
389	push @unblock_pool, $Coro::current;
390	schedule;
391	}
392	}
393
394	our $unblock_scheduler = async {	536	our $unblock_scheduler = new Coro sub {
395	while () {	537	while () {
396	while (my $cb = pop @unblock_queue) {	538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	540	my $coro = (pop @pool or new Coro \&pool_handler);
398	$handler->{arg} = $cb;	541
		542	$coro->{_invoke} = $cb;
399	$handler->ready;	543	$coro->ready;
400	cede;	544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	545	}
402		546	schedule; # sleep well
403	schedule;
404	}	547	}
405	};	548	};
		549	$unblock_scheduler->desc ("[unblock_sub scheduler]");
406		550
407	sub unblock_sub(&) {	551	sub unblock_sub(&) {
408	my $cb = shift;	552	my $cb = shift;
409		553
410	sub {	554	sub {
411	push @unblock_queue, [$cb, @_];	555	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	556	$unblock_scheduler->ready;
413	}	557	}
414	}	558	}
415		559
416	=back	560	=back
…		…
423		567
424	- 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
425	destruction. very bad things might happen otherwise (usually segfaults).	569	destruction. very bad things might happen otherwise (usually segfaults).
426		570
427	- 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
428	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
429	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
430	this).	574	this).
431		575
432	=head1 SEE ALSO	576	=head1 SEE ALSO
433		577

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Comparing Coro/Coro.pm (file contents): Revision 1.93 by root, Fri Dec 1 19:41:06 2006 UTC vs. Revision 1.132 by root, Thu Sep 20 22:53:23 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.93 by root, Fri Dec 1 19:41:06 2006 UTC vs.
Revision 1.132 by root, Thu Sep 20 22:53:23 2007 UTC