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

Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.125 by root, Fri Apr 27 19:35:58 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 $VERSION = '3.62';
47		56
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
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<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
112	}	120	if $current;
113		121
114	$current = $main;	122	_set_current $main;
115		123
116	sub current() { $current }	124	sub current() { $current }
117		125
118	=item $idle	126	=item $idle
119		127
…		…
129	handlers), then it must be prepared to be called recursively.	137	handlers), then it must be prepared to be called recursively.
130		138
131	=cut	139	=cut
132		140
133	$idle = sub {	141	$idle = sub {
134	print STDERR "FATAL: deadlock detected\n";	142	require Carp;
135	exit (51);	143	Carp::croak ("FATAL: deadlock detected");
136	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
137		157
138	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	159	# cannot destroy itself.
140	my @destroy;	160	my @destroy;
		161	my $manager;
		162
141	my $manager; $manager = new Coro sub {	163	$manager = new Coro sub {
142	while () {	164	while () {
143	# by overwriting the state object with the manager we destroy it	165	(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) {	166	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		167
153	# the next line destroys the coro state, but keeps the
154	# coroutine itself intact (we basically make it a zombie
155	# coroutine that always runs the manager thread, so it's possible
156	# to transfer() to this coroutine).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	168	&schedule;
160	}	169	}
161	};	170	};
		171
		172	$manager->prio (PRIO_MAX);
162		173
163	# static methods. not really.	174	# static methods. not really.
164		175
165	=back	176	=back
166		177
…		…
174		185
175	Create a new asynchronous coroutine and return it's coroutine object	186	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new coroutine is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	188	terminated.
178		189
179	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
180		191	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	192	just as it would in the main program.
182	program.
183		193
184	# create a new coroutine that just prints its arguments	194	# create a new coroutine that just prints its arguments
185	async {	195	async {
186	print "@_\n";	196	print "@_\n";
187	} 1,2,3,4;	197	} 1,2,3,4;
188		198
189	=cut	199	=cut
190		200
191	sub async(&@) {	201	sub async(&@) {
192	my $pid = new Coro @_;	202	my $coro = new Coro @_;
193	$pid->ready;	203	$coro->ready;
194	$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 or new Coro \&pool_handler);
		255
		256	$coro->{_invoke} = [@_];
		257	$coro->ready;
		258
		259	$coro
195	}	260	}
196		261
197	=item schedule	262	=item schedule
198		263
199	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
…		…
212	# wake up sleeping coroutine	277	# wake up sleeping coroutine
213	$current->ready;	278	$current->ready;
214	undef $current;	279	undef $current;
215	};	280	};
216		281
217	# call schedule until event occured.	282	# call schedule until event occurred.
218	# in case we are woken up for other reasons	283	# in case we are woken up for other reasons
219	# (current still defined), loop.	284	# (current still defined), loop.
220	Coro::schedule while $current;	285	Coro::schedule while $current;
221	}	286	}
222		287
223	=item cede	288	=item cede
224		289
225	"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
226	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
227	current "timeslice" to other coroutines of the same or higher priority.	292	current "timeslice" to other coroutines of the same or higher priority.
		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.
228		302
229	=item terminate [arg...]	303	=item terminate [arg...]
230		304
231	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>).
232		306
…		…
251	Create a new coroutine and return it. When the sub returns the coroutine	325	Create a new coroutine and return it. When the sub returns the coroutine
252	automatically terminates as if C<terminate> with the returned values were	326	automatically terminates as if C<terminate> with the returned values were
253	called. To make the coroutine run you must first put it into the ready queue	327	called. To make the coroutine run you must first put it into the ready queue
254	by calling the ready method.	328	by calling the ready method.
255		329
256	Calling C<exit> in a coroutine will not work correctly, so do not do that.	330	See C<async> for additional discussion.
257		331
258	=cut	332	=cut
259		333
260	sub _new_coro {	334	sub _run_coro {
261	terminate &{+shift};	335	terminate &{+shift};
262	}	336	}
263		337
264	sub new {	338	sub new {
265	my $class = shift;	339	my $class = shift;
266		340
267	$class->SUPER::new (\&_new_coro, @_)	341	$class->SUPER::new (\&_run_coro, @_)
268	}	342	}
269		343
270	=item $success = $coroutine->ready	344	=item $success = $coroutine->ready
271		345
272	Put the given coroutine into the ready queue (according to it's priority)	346	Put the given coroutine into the ready queue (according to it's priority)
…		…
278	Return wether the coroutine is currently the ready queue or not,	352	Return wether the coroutine is currently the ready queue or not,
279		353
280	=item $coroutine->cancel (arg...)	354	=item $coroutine->cancel (arg...)
281		355
282	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
283	status (default: the empty list).	357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
284		359
285	=cut	360	=cut
286		361
287	sub cancel {	362	sub cancel {
288	my $self = shift;	363	my $self = shift;
289	$self->{status} = [@_];	364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
290	push @destroy, $self;	367	push @destroy, $self;
291	$manager->ready;	368	$manager->ready;
292	&schedule if $current == $self;	369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
293	}	373	}
294		374
295	=item $coroutine->join	375	=item $coroutine->join
296		376
297	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
…		…
300		380
301	=cut	381	=cut
302		382
303	sub join {	383	sub join {
304	my $self = shift;	384	my $self = shift;
		385
305	unless ($self->{status}) {	386	unless ($self->{status}) {
306	push @{$self->{join}}, $current;	387	my $current = $current;
307	&schedule;	388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
308	}	395	}
		396
309	wantarray ? @{$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;
310	}	412	}
311		413
312	=item $oldprio = $coroutine->prio ($newprio)	414	=item $oldprio = $coroutine->prio ($newprio)
313		415
314	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
…		…
349	$old;	451	$old;
350	}	452	}
351		453
352	=back	454	=back
353		455
354	=head2 UTILITY FUNCTIONS	456	=head2 GLOBAL FUNCTIONS
355		457
356	=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 switched 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 object
		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
357		501
358	=item unblock_sub { ... }	502	=item unblock_sub { ... }
359		503
360	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,
361	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
362	immediately without blocking, returning nothing, while the original code	506	immediately without blocking, returning nothing, while the original code
363	ref will be called (with parameters) from within its own coroutine.	507	ref will be called (with parameters) from within its own coroutine.
364		508
365	The reason this fucntion exists is that many event libraries (such as the	509	The reason this function exists is that many event libraries (such as the
366	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	510	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
367	of thread-safety). This means you must not block within event callbacks,	511	of thread-safety). This means you must not block within event callbacks,
368	otherwise you might suffer from crashes or worse.	512	otherwise you might suffer from crashes or worse.
369		513
370	This function allows your callbacks to block by executing them in another	514	This function allows your callbacks to block by executing them in another
…		…
375	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
376	creating event callbacks that want to block.	520	creating event callbacks that want to block.
377		521
378	=cut	522	=cut
379		523
380	our @unblock_pool;
381	our @unblock_queue;	524	our @unblock_queue;
382	our $UNBLOCK_POOL_SIZE = 2;
383		525
384	sub unblock_handler_ {	526	# we create a special coro because we want to cede,
385	while () {	527	# to reduce pressure on the coro pool (because most callbacks
386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	528	# return immediately and can be reused) and because we cannot cede
387	$cb->(@arg);	529	# inside an event callback.
388
389	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
390	push @unblock_pool, $Coro::current;
391	schedule;
392	}
393	}
394
395	our $unblock_scheduler = async {	530	our $unblock_scheduler = async {
396	while () {	531	while () {
397	while (my $cb = pop @unblock_queue) {	532	while (my $cb = pop @unblock_queue) {
		533	# this is an inlined copy of async_pool
398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	534	my $coro = (pop @pool or new Coro \&pool_handler);
399	$handler->{arg} = $cb;	535
		536	$coro->{_invoke} = $cb;
400	$handler->ready;	537	$coro->ready;
401	cede;	538	cede; # for short-lived callbacks, this reduces pressure on the coro pool
402	}	539	}
403		540	schedule; # sleep well
404	schedule;
405	}	541	}
406	};	542	};
407		543
408	sub unblock_sub(&) {	544	sub unblock_sub(&) {
409	my $cb = shift;	545	my $cb = shift;
410		546
411	sub {	547	sub {
412	push @unblock_queue, [$cb, @_];	548	unshift @unblock_queue, [$cb, @_];
413	$unblock_scheduler->ready;	549	$unblock_scheduler->ready;
414	}	550	}
415	}	551	}
416		552
417	=back	553	=back
…		…
424		560
425	- you must make very sure that no coro is still active on global	561	- you must make very sure that no coro is still active on global
426	destruction. very bad things might happen otherwise (usually segfaults).	562	destruction. very bad things might happen otherwise (usually segfaults).
427		563
428	- this module is not thread-safe. You should only ever use this module	564	- this module is not thread-safe. You should only ever use this module
429	from the same thread (this requirement might be losened in the future	565	from the same thread (this requirement might be loosened in the future
430	to allow per-thread schedulers, but Coro::State does not yet allow	566	to allow per-thread schedulers, but Coro::State does not yet allow
431	this).	567	this).
432		568
433	=head1 SEE ALSO	569	=head1 SEE ALSO
434		570

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Comparing Coro/Coro.pm (file contents): Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs. Revision 1.125 by root, Fri Apr 27 19:35:58 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.125 by root, Fri Apr 27 19:35:58 2007 UTC