[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 1.137 by root, Wed Sep 26 19:26:48 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
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 {
		161	$current->{_trace_cb}->();
		162	}
137		163
138	# this coroutine is necessary because a coroutine	164	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	165	# cannot destroy itself.
140	my @destroy;	166	my @destroy;
		167	my $manager;
		168
141	my $manager; $manager = new Coro sub {	169	$manager = new Coro sub {
142	while () {	170	while () {
143	# by overwriting the state object with the manager we destroy it	171	(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) {	172	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		173
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;	174	&schedule;
160	}	175	}
161	};	176	};
		177	$manager->desc ("[coro manager]");
		178	$manager->prio (PRIO_MAX);
162		179
163	# static methods. not really.	180	# static methods. not really.
164		181
165	=back	182	=back
166		183
…		…
174		191
175	Create a new asynchronous coroutine and return it's coroutine object	192	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new coroutine is automatically	193	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	194	terminated.
178		195
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	196	Calling C<exit> in a coroutine will do the same as calling exit outside
180		197	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	198	just as it would in the main program.
182	program.
183		199
184	# create a new coroutine that just prints its arguments	200	# create a new coroutine that just prints its arguments
185	async {	201	async {
186	print "@_\n";	202	print "@_\n";
187	} 1,2,3,4;	203	} 1,2,3,4;
188		204
189	=cut	205	=cut
190		206
191	sub async(&@) {	207	sub async(&@) {
192	my $pid = new Coro @_;	208	my $coro = new Coro @_;
193	$pid->ready;	209	$coro->ready;
194	$pid	210	$coro
		211	}
		212
		213	=item async_pool { ... } [@args...]
		214
		215	Similar to C<async>, but uses a coroutine pool, so you should not call
		216	terminate or join (although you are allowed to), and you get a coroutine
		217	that might have executed other code already (which can be good or bad :).
		218
		219	Also, the block is executed in an C<eval> context and a warning will be
		220	issued in case of an exception instead of terminating the program, as
		221	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		222	will not work in the expected way, unless you call terminate or cancel,
		223	which somehow defeats the purpose of pooling.
		224
		225	The priority will be reset to C<0> after each job, otherwise the coroutine
		226	will be re-used "as-is".
		227
		228	The pool size is limited to 8 idle coroutines (this can be adjusted by
		229	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		230	required.
		231
		232	If you are concerned about pooled coroutines growing a lot because a
		233	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		234	{ terminate }> once per second or so to slowly replenish the pool. In
		235	addition to that, when the stacks used by a handler grows larger than 16kb
		236	(adjustable with $Coro::POOL_RSS) it will also exit.
		237
		238	=cut
		239
		240	our $POOL_SIZE = 8;
		241	our $POOL_RSS = 16 * 1024;
		242	our @async_pool;
		243
		244	sub pool_handler {
		245	my $cb;
		246
		247	while () {
		248	eval {
		249	while () {
		250	_pool_1 $cb;
		251	&$cb;
		252	_pool_2 $cb;
		253	&schedule;
		254	}
		255	};
		256
		257	last if $@ eq "\3terminate\2\n";
		258	warn $@ if $@;
		259	}
		260	}
		261
		262	sub async_pool(&@) {
		263	# this is also inlined into the unlock_scheduler
		264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		265
		266	$coro->{_invoke} = [@_];
		267	$coro->ready;
		268
		269	$coro
195	}	270	}
196		271
197	=item schedule	272	=item schedule
198		273
199	Calls the scheduler. Please note that the current coroutine will not be put	274	Calls the scheduler. Please note that the current coroutine will not be put
…		…
212	# wake up sleeping coroutine	287	# wake up sleeping coroutine
213	$current->ready;	288	$current->ready;
214	undef $current;	289	undef $current;
215	};	290	};
216		291
217	# call schedule until event occured.	292	# call schedule until event occurred.
218	# in case we are woken up for other reasons	293	# in case we are woken up for other reasons
219	# (current still defined), loop.	294	# (current still defined), loop.
220	Coro::schedule while $current;	295	Coro::schedule while $current;
221	}	296	}
222		297
223	=item cede	298	=item cede
224		299
225	"Cede" to other coroutines. This function puts the current coroutine into the	300	"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	301	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.	302	current "timeslice" to other coroutines of the same or higher priority.
		303
		304	Returns true if at least one coroutine switch has happened.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to any
		309	coroutine, regardless of priority, once.
		310
		311	Returns true if at least one coroutine switch has happened.
228		312
229	=item terminate [arg...]	313	=item terminate [arg...]
230		314
231	Terminates the current coroutine with the given status values (see L<cancel>).	315	Terminates the current coroutine with the given status values (see L<cancel>).
232		316
…		…
251	Create a new coroutine and return it. When the sub returns the coroutine	335	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	336	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	337	called. To make the coroutine run you must first put it into the ready queue
254	by calling the ready method.	338	by calling the ready method.
255		339
256	Calling C<exit> in a coroutine will not work correctly, so do not do that.	340	See C<async> for additional discussion.
257		341
258	=cut	342	=cut
259		343
260	sub _new_coro {	344	sub _run_coro {
261	terminate &{+shift};	345	terminate &{+shift};
262	}	346	}
263		347
264	sub new {	348	sub new {
265	my $class = shift;	349	my $class = shift;
266		350
267	$class->SUPER::new (\&_new_coro, @_)	351	$class->SUPER::new (\&_run_coro, @_)
268	}	352	}
269		353
270	=item $success = $coroutine->ready	354	=item $success = $coroutine->ready
271		355
272	Put the given coroutine into the ready queue (according to it's priority)	356	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,	362	Return wether the coroutine is currently the ready queue or not,
279		363
280	=item $coroutine->cancel (arg...)	364	=item $coroutine->cancel (arg...)
281		365
282	Terminates the given coroutine and makes it return the given arguments as	366	Terminates the given coroutine and makes it return the given arguments as
283	status (default: the empty list).	367	status (default: the empty list). Never returns if the coroutine is the
		368	current coroutine.
284		369
285	=cut	370	=cut
286		371
287	sub cancel {	372	sub cancel {
288	my $self = shift;	373	my $self = shift;
289	$self->{status} = [@_];	374	$self->{status} = [@_];
		375
		376	if ($current == $self) {
290	push @destroy, $self;	377	push @destroy, $self;
291	$manager->ready;	378	$manager->ready;
292	&schedule if $current == $self;	379	&schedule while 1;
		380	} else {
		381	$self->_cancel;
		382	}
293	}	383	}
294		384
295	=item $coroutine->join	385	=item $coroutine->join
296		386
297	Wait until the coroutine terminates and return any values given to the	387	Wait until the coroutine terminates and return any values given to the
…		…
300		390
301	=cut	391	=cut
302		392
303	sub join {	393	sub join {
304	my $self = shift;	394	my $self = shift;
		395
305	unless ($self->{status}) {	396	unless ($self->{status}) {
306	push @{$self->{join}}, $current;	397	my $current = $current;
307	&schedule;	398
		399	push @{$self->{destroy_cb}}, sub {
		400	$current->ready;
		401	undef $current;
		402	};
		403
		404	&schedule while $current;
308	}	405	}
		406
309	wantarray ? @{$self->{status}} : $self->{status}[0];	407	wantarray ? @{$self->{status}} : $self->{status}[0];
		408	}
		409
		410	=item $coroutine->on_destroy (\&cb)
		411
		412	Registers a callback that is called when this coroutine gets destroyed,
		413	but before it is joined. The callback gets passed the terminate arguments,
		414	if any.
		415
		416	=cut
		417
		418	sub on_destroy {
		419	my ($self, $cb) = @_;
		420
		421	push @{ $self->{destroy_cb} }, $cb;
310	}	422	}
311		423
312	=item $oldprio = $coroutine->prio ($newprio)	424	=item $oldprio = $coroutine->prio ($newprio)
313		425
314	Sets (or gets, if the argument is missing) the priority of the	426	Sets (or gets, if the argument is missing) the priority of the
…		…
349	$old;	461	$old;
350	}	462	}
351		463
352	=back	464	=back
353		465
354	=head2 UTILITY FUNCTIONS	466	=head2 GLOBAL FUNCTIONS
355		467
356	=over 4	468	=over 4
		469
		470	=item Coro::nready
		471
		472	Returns the number of coroutines that are currently in the ready state,
		473	i.e. that can be switched to. The value C<0> means that the only runnable
		474	coroutine is the currently running one, so C<cede> would have no effect,
		475	and C<schedule> would cause a deadlock unless there is an idle handler
		476	that wakes up some coroutines.
		477
		478	=item my $guard = Coro::guard { ... }
		479
		480	This creates and returns a guard object. Nothing happens until the object
		481	gets destroyed, in which case the codeblock given as argument will be
		482	executed. This is useful to free locks or other resources in case of a
		483	runtime error or when the coroutine gets canceled, as in both cases the
		484	guard block will be executed. The guard object supports only one method,
		485	C<< ->cancel >>, which will keep the codeblock from being executed.
		486
		487	Example: set some flag and clear it again when the coroutine gets canceled
		488	or the function returns:
		489
		490	sub do_something {
		491	my $guard = Coro::guard { $busy = 0 };
		492	$busy = 1;
		493
		494	# do something that requires $busy to be true
		495	}
		496
		497	=cut
		498
		499	sub guard(&) {
		500	bless \(my $cb = $_[0]), "Coro::guard"
		501	}
		502
		503	sub Coro::guard::cancel {
		504	${$_[0]} = sub { };
		505	}
		506
		507	sub Coro::guard::DESTROY {
		508	${$_[0]}->();
		509	}
		510
357		511
358	=item unblock_sub { ... }	512	=item unblock_sub { ... }
359		513
360	This utility function takes a BLOCK or code reference and "unblocks" it,	514	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	515	returning the new coderef. This means that the new coderef will return
362	immediately without blocking, returning nothing, while the original code	516	immediately without blocking, returning nothing, while the original code
363	ref will be called (with parameters) from within its own coroutine.	517	ref will be called (with parameters) from within its own coroutine.
364		518
365	The reason this fucntion exists is that many event libraries (such as the	519	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	520	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,	521	of thread-safety). This means you must not block within event callbacks,
368	otherwise you might suffer from crashes or worse.	522	otherwise you might suffer from crashes or worse.
369		523
370	This function allows your callbacks to block by executing them in another	524	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	529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
376	creating event callbacks that want to block.	530	creating event callbacks that want to block.
377		531
378	=cut	532	=cut
379		533
380	our @unblock_pool;
381	our @unblock_queue;	534	our @unblock_queue;
382	our $UNBLOCK_POOL_SIZE = 2;
383		535
384	sub unblock_handler_ {	536	# we create a special coro because we want to cede,
385	while () {	537	# to reduce pressure on the coro pool (because most callbacks
386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	538	# return immediately and can be reused) and because we cannot cede
387	$cb->(@arg);	539	# 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 {	540	our $unblock_scheduler = new Coro sub {
396	while () {	541	while () {
397	while (my $cb = pop @unblock_queue) {	542	while (my $cb = pop @unblock_queue) {
398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	543	# this is an inlined copy of async_pool
399	$handler->{arg} = $cb;	544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		545
		546	$coro->{_invoke} = $cb;
400	$handler->ready;	547	$coro->ready;
401	cede;	548	cede; # for short-lived callbacks, this reduces pressure on the coro pool
402	}	549	}
403		550	schedule; # sleep well
404	schedule;
405	}	551	}
406	};	552	};
		553	$unblock_scheduler->desc ("[unblock_sub scheduler]");
407		554
408	sub unblock_sub(&) {	555	sub unblock_sub(&) {
409	my $cb = shift;	556	my $cb = shift;
410		557
411	sub {	558	sub {
412	push @unblock_queue, [$cb, @_];	559	unshift @unblock_queue, [$cb, @_];
413	$unblock_scheduler->ready;	560	$unblock_scheduler->ready;
414	}	561	}
415	}	562	}
416		563
417	=back	564	=back
…		…
424		571
425	- you must make very sure that no coro is still active on global	572	- you must make very sure that no coro is still active on global
426	destruction. very bad things might happen otherwise (usually segfaults).	573	destruction. very bad things might happen otherwise (usually segfaults).
427		574
428	- this module is not thread-safe. You should only ever use this module	575	- 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	576	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	577	to allow per-thread schedulers, but Coro::State does not yet allow
431	this).	578	this).
432		579
433	=head1 SEE ALSO	580	=head1 SEE ALSO
434		581

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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 1.137 by root, Wed Sep 26 19:26:48 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 1.137 by root, Wed Sep 26 19:26:48 2007 UTC