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

Comparing Coro/Coro.pm (file contents):
Revision 1.96 by root, Mon Dec 4 03:48:16 2006 UTC vs.
Revision 1.128 by root, Wed Sep 19 21:39:15 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 = '3.01';	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
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
…		…
132	$idle = sub {	141	$idle = sub {
133	require Carp;	142	require Carp;
134	Carp::croak ("FATAL: deadlock detected");	143	Carp::croak ("FATAL: deadlock detected");
135	};	144	};
136		145
		146	sub _cancel {
		147	my ($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	}
		157
137	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
138	# cannot destroy itself.	159	# cannot destroy itself.
139	my @destroy;	160	my @destroy;
		161	my $manager;
		162
140	my $manager; $manager = new Coro sub {	163	$manager = new Coro sub {
141	while () {	164	while () {
142	# by overwriting the state object with the manager we destroy it	165	(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) {	166	while @destroy;
148	my $coro = pop @destroy;
149	$coro->{status} \|\|= [];
150	$_->ready for @{delete $coro->{join} \|\| []};
151		167
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;	168	&schedule;
159	}	169	}
160	};	170	};
		171
		172	$manager->prio (PRIO_MAX);
161		173
162	# static methods. not really.	174	# static methods. not really.
163		175
164	=back	176	=back
165		177
…		…
173		185
174	Create a new asynchronous coroutine and return it's coroutine object	186	Create a new asynchronous coroutine and return it's coroutine object
175	(usually unused). When the sub returns the new coroutine is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
176	terminated.	188	terminated.
177		189
178	Calling C<exit> in a coroutine will not work correctly, so do not do that.	190	Calling C<exit> in a coroutine will do the same as calling exit outside
179		191	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	192	just as it would in the main program.
181	program.
182		193
183	# create a new coroutine that just prints its arguments	194	# create a new coroutine that just prints its arguments
184	async {	195	async {
185	print "@_\n";	196	print "@_\n";
186	} 1,2,3,4;	197	} 1,2,3,4;
187		198
188	=cut	199	=cut
189		200
190	sub async(&@) {	201	sub async(&@) {
191	my $pid = new Coro @_;	202	my $coro = new Coro @_;
192	$pid->ready;	203	$coro->ready;
193	$pid	204	$coro
		205	}
		206
		207	=item async_pool { ... } [@args...]
		208
		209	Similar to C<async>, but uses a coroutine pool, so you should not call
		210	terminate or join (although you are allowed to), and you get a coroutine
		211	that might have executed other code already (which can be good or bad :).
		212
		213	Also, the block is executed in an C<eval> context and a warning will be
		214	issued in case of an exception instead of terminating the program, as
		215	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		216	will not work in the expected way, unless you call terminate or cancel,
		217	which somehow defeats the purpose of pooling.
		218
		219	The priority will be reset to C<0> after each job, otherwise the coroutine
		220	will be re-used "as-is".
		221
		222	The pool size is limited to 8 idle coroutines (this can be adjusted by
		223	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		224	required.
		225
		226	If you are concerned about pooled coroutines growing a lot because a
		227	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		228	terminate }> once per second or so to slowly replenish the pool.
		229
		230	=cut
		231
		232	our $POOL_SIZE = 8;
		233	our @pool;
		234
		235	sub pool_handler {
		236	while () {
		237	eval {
		238	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		239	$cb->(@arg);
		240	};
		241	warn $@ if $@;
		242
		243	last if @pool >= $POOL_SIZE;
		244	push @pool, $current;
		245
		246	$current->save (Coro::State::SAVE_DEF);
		247	$current->prio (0);
		248	schedule;
		249	}
		250	}
		251
		252	sub async_pool(&@) {
		253	# this is also inlined into the unlock_scheduler
		254	my $coro = (pop @pool) \|\| do {
		255	my $coro = new Coro \&pool_handler;
		256	$coro->{desc} = "async_pool";
		257	$coro
		258	};
		259
		260	$coro->{_invoke} = [@_];
		261	$coro->ready;
		262
		263	$coro
194	}	264	}
195		265
196	=item schedule	266	=item schedule
197		267
198	Calls the scheduler. Please note that the current coroutine will not be put	268	Calls the scheduler. Please note that the current coroutine will not be put
…		…
211	# wake up sleeping coroutine	281	# wake up sleeping coroutine
212	$current->ready;	282	$current->ready;
213	undef $current;	283	undef $current;
214	};	284	};
215		285
216	# call schedule until event occured.	286	# call schedule until event occurred.
217	# in case we are woken up for other reasons	287	# in case we are woken up for other reasons
218	# (current still defined), loop.	288	# (current still defined), loop.
219	Coro::schedule while $current;	289	Coro::schedule while $current;
220	}	290	}
221		291
222	=item cede	292	=item cede
223		293
224	"Cede" to other coroutines. This function puts the current coroutine into the	294	"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	295	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.	296	current "timeslice" to other coroutines of the same or higher priority.
		297
		298	Returns true if at least one coroutine switch has happened.
		299
		300	=item Coro::cede_notself
		301
		302	Works like cede, but is not exported by default and will cede to any
		303	coroutine, regardless of priority, once.
		304
		305	Returns true if at least one coroutine switch has happened.
227		306
228	=item terminate [arg...]	307	=item terminate [arg...]
229		308
230	Terminates the current coroutine with the given status values (see L<cancel>).	309	Terminates the current coroutine with the given status values (see L<cancel>).
231		310
…		…
250	Create a new coroutine and return it. When the sub returns the coroutine	329	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	330	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	331	called. To make the coroutine run you must first put it into the ready queue
253	by calling the ready method.	332	by calling the ready method.
254		333
255	Calling C<exit> in a coroutine will not work correctly, so do not do that.	334	See C<async> for additional discussion.
256		335
257	=cut	336	=cut
258		337
259	sub _run_coro {	338	sub _run_coro {
260	terminate &{+shift};	339	terminate &{+shift};
…		…
277	Return wether the coroutine is currently the ready queue or not,	356	Return wether the coroutine is currently the ready queue or not,
278		357
279	=item $coroutine->cancel (arg...)	358	=item $coroutine->cancel (arg...)
280		359
281	Terminates the given coroutine and makes it return the given arguments as	360	Terminates the given coroutine and makes it return the given arguments as
282	status (default: the empty list).	361	status (default: the empty list). Never returns if the coroutine is the
		362	current coroutine.
283		363
284	=cut	364	=cut
285		365
286	sub cancel {	366	sub cancel {
287	my $self = shift;	367	my $self = shift;
288	$self->{status} = [@_];	368	$self->{status} = [@_];
		369
		370	if ($current == $self) {
289	push @destroy, $self;	371	push @destroy, $self;
290	$manager->ready;	372	$manager->ready;
291	&schedule if $current == $self;	373	&schedule while 1;
		374	} else {
		375	$self->_cancel;
		376	}
292	}	377	}
293		378
294	=item $coroutine->join	379	=item $coroutine->join
295		380
296	Wait until the coroutine terminates and return any values given to the	381	Wait until the coroutine terminates and return any values given to the
…		…
299		384
300	=cut	385	=cut
301		386
302	sub join {	387	sub join {
303	my $self = shift;	388	my $self = shift;
		389
304	unless ($self->{status}) {	390	unless ($self->{status}) {
305	push @{$self->{join}}, $current;	391	my $current = $current;
306	&schedule;	392
		393	push @{$self->{destroy_cb}}, sub {
		394	$current->ready;
		395	undef $current;
		396	};
		397
		398	&schedule while $current;
307	}	399	}
		400
308	wantarray ? @{$self->{status}} : $self->{status}[0];	401	wantarray ? @{$self->{status}} : $self->{status}[0];
		402	}
		403
		404	=item $coroutine->on_destroy (\&cb)
		405
		406	Registers a callback that is called when this coroutine gets destroyed,
		407	but before it is joined. The callback gets passed the terminate arguments,
		408	if any.
		409
		410	=cut
		411
		412	sub on_destroy {
		413	my ($self, $cb) = @_;
		414
		415	push @{ $self->{destroy_cb} }, $cb;
309	}	416	}
310		417
311	=item $oldprio = $coroutine->prio ($newprio)	418	=item $oldprio = $coroutine->prio ($newprio)
312		419
313	Sets (or gets, if the argument is missing) the priority of the	420	Sets (or gets, if the argument is missing) the priority of the
…		…
348	$old;	455	$old;
349	}	456	}
350		457
351	=back	458	=back
352		459
353	=head2 UTILITY FUNCTIONS	460	=head2 GLOBAL FUNCTIONS
354		461
355	=over 4	462	=over 4
		463
		464	=item Coro::nready
		465
		466	Returns the number of coroutines that are currently in the ready state,
		467	i.e. that can be switched to. The value C<0> means that the only runnable
		468	coroutine is the currently running one, so C<cede> would have no effect,
		469	and C<schedule> would cause a deadlock unless there is an idle handler
		470	that wakes up some coroutines.
		471
		472	=item my $guard = Coro::guard { ... }
		473
		474	This creates and returns a guard object. Nothing happens until the object
		475	gets destroyed, in which case the codeblock given as argument will be
		476	executed. This is useful to free locks or other resources in case of a
		477	runtime error or when the coroutine gets canceled, as in both cases the
		478	guard block will be executed. The guard object supports only one method,
		479	C<< ->cancel >>, which will keep the codeblock from being executed.
		480
		481	Example: set some flag and clear it again when the coroutine gets canceled
		482	or the function returns:
		483
		484	sub do_something {
		485	my $guard = Coro::guard { $busy = 0 };
		486	$busy = 1;
		487
		488	# do something that requires $busy to be true
		489	}
		490
		491	=cut
		492
		493	sub guard(&) {
		494	bless \(my $cb = $_[0]), "Coro::guard"
		495	}
		496
		497	sub Coro::guard::cancel {
		498	${$_[0]} = sub { };
		499	}
		500
		501	sub Coro::guard::DESTROY {
		502	${$_[0]}->();
		503	}
		504
356		505
357	=item unblock_sub { ... }	506	=item unblock_sub { ... }
358		507
359	This utility function takes a BLOCK or code reference and "unblocks" it,	508	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	509	returning the new coderef. This means that the new coderef will return
361	immediately without blocking, returning nothing, while the original code	510	immediately without blocking, returning nothing, while the original code
362	ref will be called (with parameters) from within its own coroutine.	511	ref will be called (with parameters) from within its own coroutine.
363		512
364	The reason this fucntion exists is that many event libraries (such as the	513	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	514	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,	515	of thread-safety). This means you must not block within event callbacks,
367	otherwise you might suffer from crashes or worse.	516	otherwise you might suffer from crashes or worse.
368		517
369	This function allows your callbacks to block by executing them in another	518	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	523	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
375	creating event callbacks that want to block.	524	creating event callbacks that want to block.
376		525
377	=cut	526	=cut
378		527
379	our @unblock_pool;
380	our @unblock_queue;	528	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		529
383	sub unblock_handler_ {	530	# we create a special coro because we want to cede,
384	while () {	531	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	532	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	533	# 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 {	534	our $unblock_scheduler = async {
395	while () {	535	while () {
396	while (my $cb = pop @unblock_queue) {	536	while (my $cb = pop @unblock_queue) {
		537	# this is an inlined copy of async_pool
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	538	my $coro = (pop @pool or new Coro \&pool_handler);
398	$handler->{arg} = $cb;	539
		540	$coro->{_invoke} = $cb;
399	$handler->ready;	541	$coro->ready;
400	cede;	542	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	543	}
402		544	schedule; # sleep well
403	schedule;
404	}	545	}
405	};	546	};
406		547
407	sub unblock_sub(&) {	548	sub unblock_sub(&) {
408	my $cb = shift;	549	my $cb = shift;
409		550
410	sub {	551	sub {
411	push @unblock_queue, [$cb, @_];	552	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	553	$unblock_scheduler->ready;
413	}	554	}
414	}	555	}
415		556
416	=back	557	=back
…		…
423		564
424	- you must make very sure that no coro is still active on global	565	- you must make very sure that no coro is still active on global
425	destruction. very bad things might happen otherwise (usually segfaults).	566	destruction. very bad things might happen otherwise (usually segfaults).
426		567
427	- this module is not thread-safe. You should only ever use this module	568	- 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	569	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	570	to allow per-thread schedulers, but Coro::State does not yet allow
430	this).	571	this).
431		572
432	=head1 SEE ALSO	573	=head1 SEE ALSO
433		574

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.96 by root, Mon Dec 4 03:48:16 2006 UTC vs. Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.96 by root, Mon Dec 4 03:48:16 2006 UTC vs.
Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC