[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 1.114 by root, Wed Jan 24 16:22:08 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 use din this module also
		26	guarentees 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 $VERSION = '3.5';
47		56
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
…		…
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
…		…
186	} 1,2,3,4;	198	} 1,2,3,4;
187		199
188	=cut	200	=cut
189		201
190	sub async(&@) {	202	sub async(&@) {
191	my $pid = new Coro @_;	203	my $coro = new Coro @_;
192	$pid->ready;	204	$coro->ready;
193	$pid	205	$coro
		206	}
		207
		208	=item async_pool { ... } [@args...]
		209
		210	Similar to C<async>, but uses a coroutine pool, so you should not call
		211	terminate or join (although you are allowed to), and you get a coroutine
		212	that might have executed other code already (which can be good or bad :).
		213
		214	Also, the block is executed in an C<eval> context and a warning will be
		215	issued in case of an exception instead of terminating the program, as
		216	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		217	will not work in the expected way, unless you call terminate or cancel,
		218	which somehow defeats the purpose of pooling.
		219
		220	The priority will be reset to C<0> after each job, otherwise the coroutine
		221	will be re-used "as-is".
		222
		223	The pool size is limited to 8 idle coroutines (this can be adjusted by
		224	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		225	required.
		226
		227	If you are concerned about pooled coroutines growing a lot because a
		228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		229	terminate }> once per second or so to slowly replenish the pool.
		230
		231	=cut
		232
		233	our $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	eval {
		239	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		240	$cb->(@arg);
		241	};
		242	warn $@ if $@;
		243
		244	last if @pool >= $POOL_SIZE;
		245	push @pool, $current;
		246
		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 or new Coro \&pool_handler);
		255
		256	$coro->{_invoke} = [@_];
		257	$coro->ready;
		258
		259	$coro
194	}	260	}
195		261
196	=item schedule	262	=item schedule
197		263
198	Calls the scheduler. Please note that the current coroutine will not be put	264	Calls the scheduler. Please note that the current coroutine will not be put
…		…
223		289
224	"Cede" to other coroutines. This function puts the current coroutine into the	290	"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	291	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.	292	current "timeslice" to other coroutines of the same or higher priority.
227		293
		294	Returns true if at least one coroutine switch has happened.
		295
		296	=item Coro::cede_notself
		297
		298	Works like cede, but is not exported by default and will cede to any
		299	coroutine, regardless of priority, once.
		300
		301	Returns true if at least one coroutine switch has happened.
		302
228	=item terminate [arg...]	303	=item terminate [arg...]
229		304
230	Terminates the current coroutine with the given status values (see L<cancel>).	305	Terminates the current coroutine with the given status values (see L<cancel>).
231		306
232	=cut	307	=cut
…		…
277	Return wether the coroutine is currently the ready queue or not,	352	Return wether the coroutine is currently the ready queue or not,
278		353
279	=item $coroutine->cancel (arg...)	354	=item $coroutine->cancel (arg...)
280		355
281	Terminates the given coroutine and makes it return the given arguments as	356	Terminates the given coroutine and makes it return the given arguments as
282	status (default: the empty list).	357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
283		359
284	=cut	360	=cut
285		361
286	sub cancel {	362	sub cancel {
287	my $self = shift;	363	my $self = shift;
288	$self->{status} = [@_];	364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
289	push @destroy, $self;	367	push @destroy, $self;
290	$manager->ready;	368	$manager->ready;
291	&schedule if $current == $self;	369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
292	}	373	}
293		374
294	=item $coroutine->join	375	=item $coroutine->join
295		376
296	Wait until the coroutine terminates and return any values given to the	377	Wait until the coroutine terminates and return any values given to the
…		…
299		380
300	=cut	381	=cut
301		382
302	sub join {	383	sub join {
303	my $self = shift;	384	my $self = shift;
		385
304	unless ($self->{status}) {	386	unless ($self->{status}) {
305	push @{$self->{join}}, $current;	387	my $current = $current;
306	&schedule;	388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
307	}	395	}
		396
308	wantarray ? @{$self->{status}} : $self->{status}[0];	397	wantarray ? @{$self->{status}} : $self->{status}[0];
		398	}
		399
		400	=item $coroutine->on_destroy (\&cb)
		401
		402	Registers a callback that is called when this coroutine gets destroyed,
		403	but before it is joined. The callback gets passed the terminate arguments,
		404	if any.
		405
		406	=cut
		407
		408	sub on_destroy {
		409	my ($self, $cb) = @_;
		410
		411	push @{ $self->{destroy_cb} }, $cb;
309	}	412	}
310		413
311	=item $oldprio = $coroutine->prio ($newprio)	414	=item $oldprio = $coroutine->prio ($newprio)
312		415
313	Sets (or gets, if the argument is missing) the priority of the	416	Sets (or gets, if the argument is missing) the priority of the
…		…
348	$old;	451	$old;
349	}	452	}
350		453
351	=back	454	=back
352		455
353	=head2 UTILITY FUNCTIONS	456	=head2 GLOBAL FUNCTIONS
354		457
355	=over 4	458	=over 4
		459
		460	=item Coro::nready
		461
		462	Returns the number of coroutines that are currently in the ready state,
		463	i.e. that can be swicthed to. The value C<0> means that the only runnable
		464	coroutine is the currently running one, so C<cede> would have no effect,
		465	and C<schedule> would cause a deadlock unless there is an idle handler
		466	that wakes up some coroutines.
		467
		468	=item my $guard = Coro::guard { ... }
		469
		470	This creates and returns a guard object. Nothing happens until the objetc
		471	gets destroyed, in which case the codeblock given as argument will be
		472	executed. This is useful to free locks or other resources in case of a
		473	runtime error or when the coroutine gets canceled, as in both cases the
		474	guard block will be executed. The guard object supports only one method,
		475	C<< ->cancel >>, which will keep the codeblock from being executed.
		476
		477	Example: set some flag and clear it again when the coroutine gets canceled
		478	or the function returns:
		479
		480	sub do_something {
		481	my $guard = Coro::guard { $busy = 0 };
		482	$busy = 1;
		483
		484	# do something that requires $busy to be true
		485	}
		486
		487	=cut
		488
		489	sub guard(&) {
		490	bless \(my $cb = $_[0]), "Coro::guard"
		491	}
		492
		493	sub Coro::guard::cancel {
		494	${$_[0]} = sub { };
		495	}
		496
		497	sub Coro::guard::DESTROY {
		498	${$_[0]}->();
		499	}
		500
356		501
357	=item unblock_sub { ... }	502	=item unblock_sub { ... }
358		503
359	This utility function takes a BLOCK or code reference and "unblocks" it,	504	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	505	returning the new coderef. This means that the new coderef will return
…		…
374	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	519	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
375	creating event callbacks that want to block.	520	creating event callbacks that want to block.
376		521
377	=cut	522	=cut
378		523
379	our @unblock_pool;
380	our @unblock_queue;	524	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		525
383	sub unblock_handler_ {	526	# we create a special coro because we want to cede,
384	while () {	527	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	528	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	529	# 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 {	530	our $unblock_scheduler = async {
395	while () {	531	while () {
396	while (my $cb = pop @unblock_queue) {	532	while (my $cb = pop @unblock_queue) {
		533	# this is an inlined copy of async_pool
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	534	my $coro = (pop @pool or new Coro \&pool_handler);
398	$handler->{arg} = $cb;	535
		536	$coro->{_invoke} = $cb;
399	$handler->ready;	537	$coro->ready;
400	cede;	538	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	539	}
402		540	schedule; # sleep well
403	schedule;
404	}	541	}
405	};	542	};
406		543
407	sub unblock_sub(&) {	544	sub unblock_sub(&) {
408	my $cb = shift;	545	my $cb = shift;
409		546
410	sub {	547	sub {
411	push @unblock_queue, [$cb, @_];	548	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	549	$unblock_scheduler->ready;
413	}	550	}
414	}	551	}
415		552
416	=back	553	=back

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 1.114 by root, Wed Jan 24 16:22:08 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 1.114 by root, Wed Jan 24 16:22:08 2007 UTC