[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 1.129 by root, Wed Sep 19 22:33:08 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 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<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($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 {
		164	$current->desc ("[coro manager]");
		165
142	while () {	166	while () {
143	# by overwriting the state object with the manager we destroy it	167	(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) {	168	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		169
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;	170	&schedule;
160	}	171	}
161	};	172	};
		173
		174	$manager->prio (PRIO_MAX);
162		175
163	# static methods. not really.	176	# static methods. not really.
164		177
165	=back	178	=back
166		179
…		…
174		187
175	Create a new asynchronous coroutine and return it's coroutine object	188	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new coroutine is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	190	terminated.
178		191
179	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
180		193	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	194	just as it would in the main program.
182	program.
183		195
184	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
185	async {	197	async {
186	print "@_\n";	198	print "@_\n";
187	} 1,2,3,4;	199	} 1,2,3,4;
188		200
189	=cut	201	=cut
190		202
191	sub async(&@) {	203	sub async(&@) {
192	my $pid = new Coro @_;	204	my $coro = new Coro @_;
193	$pid->ready;	205	$coro->ready;
194	$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 @pool;
		236
		237	sub pool_handler {
		238	while () {
		239	$current->{desc} = "[async_pool]";
		240
		241	eval {
		242	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		243	$cb->(@arg);
		244	};
		245	warn $@ if $@;
		246
		247	last if @pool >= $POOL_SIZE;
		248
		249	push @pool, $current;
		250	$current->{desc} = "[async_pool idle]";
		251	$current->save (Coro::State::SAVE_DEF);
		252	$current->prio (0);
		253	schedule;
		254	}
		255	}
		256
		257	sub async_pool(&@) {
		258	# this is also inlined into the unlock_scheduler
		259	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		260
		261	$coro->{_invoke} = [@_];
		262	$coro->ready;
		263
		264	$coro
195	}	265	}
196		266
197	=item schedule	267	=item schedule
198		268
199	Calls the scheduler. Please note that the current coroutine will not be put	269	Calls the scheduler. Please note that the current coroutine will not be put
…		…
212	# wake up sleeping coroutine	282	# wake up sleeping coroutine
213	$current->ready;	283	$current->ready;
214	undef $current;	284	undef $current;
215	};	285	};
216		286
217	# call schedule until event occured.	287	# call schedule until event occurred.
218	# in case we are woken up for other reasons	288	# in case we are woken up for other reasons
219	# (current still defined), loop.	289	# (current still defined), loop.
220	Coro::schedule while $current;	290	Coro::schedule while $current;
221	}	291	}
222		292
223	=item cede	293	=item cede
224		294
225	"Cede" to other coroutines. This function puts the current coroutine into the	295	"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	296	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.	297	current "timeslice" to other coroutines of the same or higher priority.
		298
		299	Returns true if at least one coroutine switch has happened.
		300
		301	=item Coro::cede_notself
		302
		303	Works like cede, but is not exported by default and will cede to any
		304	coroutine, regardless of priority, once.
		305
		306	Returns true if at least one coroutine switch has happened.
228		307
229	=item terminate [arg...]	308	=item terminate [arg...]
230		309
231	Terminates the current coroutine with the given status values (see L<cancel>).	310	Terminates the current coroutine with the given status values (see L<cancel>).
232		311
…		…
251	Create a new coroutine and return it. When the sub returns the coroutine	330	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	331	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	332	called. To make the coroutine run you must first put it into the ready queue
254	by calling the ready method.	333	by calling the ready method.
255		334
256	Calling C<exit> in a coroutine will not work correctly, so do not do that.	335	See C<async> for additional discussion.
257		336
258	=cut	337	=cut
259		338
260	sub _new_coro {	339	sub _run_coro {
261	terminate &{+shift};	340	terminate &{+shift};
262	}	341	}
263		342
264	sub new {	343	sub new {
265	my $class = shift;	344	my $class = shift;
266		345
267	$class->SUPER::new (\&_new_coro, @_)	346	$class->SUPER::new (\&_run_coro, @_)
268	}	347	}
269		348
270	=item $success = $coroutine->ready	349	=item $success = $coroutine->ready
271		350
272	Put the given coroutine into the ready queue (according to it's priority)	351	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,	357	Return wether the coroutine is currently the ready queue or not,
279		358
280	=item $coroutine->cancel (arg...)	359	=item $coroutine->cancel (arg...)
281		360
282	Terminates the given coroutine and makes it return the given arguments as	361	Terminates the given coroutine and makes it return the given arguments as
283	status (default: the empty list).	362	status (default: the empty list). Never returns if the coroutine is the
		363	current coroutine.
284		364
285	=cut	365	=cut
286		366
287	sub cancel {	367	sub cancel {
288	my $self = shift;	368	my $self = shift;
289	$self->{status} = [@_];	369	$self->{status} = [@_];
		370
		371	if ($current == $self) {
290	push @destroy, $self;	372	push @destroy, $self;
291	$manager->ready;	373	$manager->ready;
292	&schedule if $current == $self;	374	&schedule while 1;
		375	} else {
		376	$self->_cancel;
		377	}
293	}	378	}
294		379
295	=item $coroutine->join	380	=item $coroutine->join
296		381
297	Wait until the coroutine terminates and return any values given to the	382	Wait until the coroutine terminates and return any values given to the
…		…
300		385
301	=cut	386	=cut
302		387
303	sub join {	388	sub join {
304	my $self = shift;	389	my $self = shift;
		390
305	unless ($self->{status}) {	391	unless ($self->{status}) {
306	push @{$self->{join}}, $current;	392	my $current = $current;
307	&schedule;	393
		394	push @{$self->{destroy_cb}}, sub {
		395	$current->ready;
		396	undef $current;
		397	};
		398
		399	&schedule while $current;
308	}	400	}
		401
309	wantarray ? @{$self->{status}} : $self->{status}[0];	402	wantarray ? @{$self->{status}} : $self->{status}[0];
		403	}
		404
		405	=item $coroutine->on_destroy (\&cb)
		406
		407	Registers a callback that is called when this coroutine gets destroyed,
		408	but before it is joined. The callback gets passed the terminate arguments,
		409	if any.
		410
		411	=cut
		412
		413	sub on_destroy {
		414	my ($self, $cb) = @_;
		415
		416	push @{ $self->{destroy_cb} }, $cb;
310	}	417	}
311		418
312	=item $oldprio = $coroutine->prio ($newprio)	419	=item $oldprio = $coroutine->prio ($newprio)
313		420
314	Sets (or gets, if the argument is missing) the priority of the	421	Sets (or gets, if the argument is missing) the priority of the
…		…
349	$old;	456	$old;
350	}	457	}
351		458
352	=back	459	=back
353		460
354	=head2 UTILITY FUNCTIONS	461	=head2 GLOBAL FUNCTIONS
355		462
356	=over 4	463	=over 4
		464
		465	=item Coro::nready
		466
		467	Returns the number of coroutines that are currently in the ready state,
		468	i.e. that can be switched to. The value C<0> means that the only runnable
		469	coroutine is the currently running one, so C<cede> would have no effect,
		470	and C<schedule> would cause a deadlock unless there is an idle handler
		471	that wakes up some coroutines.
		472
		473	=item my $guard = Coro::guard { ... }
		474
		475	This creates and returns a guard object. Nothing happens until the object
		476	gets destroyed, in which case the codeblock given as argument will be
		477	executed. This is useful to free locks or other resources in case of a
		478	runtime error or when the coroutine gets canceled, as in both cases the
		479	guard block will be executed. The guard object supports only one method,
		480	C<< ->cancel >>, which will keep the codeblock from being executed.
		481
		482	Example: set some flag and clear it again when the coroutine gets canceled
		483	or the function returns:
		484
		485	sub do_something {
		486	my $guard = Coro::guard { $busy = 0 };
		487	$busy = 1;
		488
		489	# do something that requires $busy to be true
		490	}
		491
		492	=cut
		493
		494	sub guard(&) {
		495	bless \(my $cb = $_[0]), "Coro::guard"
		496	}
		497
		498	sub Coro::guard::cancel {
		499	${$_[0]} = sub { };
		500	}
		501
		502	sub Coro::guard::DESTROY {
		503	${$_[0]}->();
		504	}
		505
357		506
358	=item unblock_sub { ... }	507	=item unblock_sub { ... }
359		508
360	This utility function takes a BLOCK or code reference and "unblocks" it,	509	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	510	returning the new coderef. This means that the new coderef will return
362	immediately without blocking, returning nothing, while the original code	511	immediately without blocking, returning nothing, while the original code
363	ref will be called (with parameters) from within its own coroutine.	512	ref will be called (with parameters) from within its own coroutine.
364		513
365	The reason this fucntion exists is that many event libraries (such as the	514	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	515	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,	516	of thread-safety). This means you must not block within event callbacks,
368	otherwise you might suffer from crashes or worse.	517	otherwise you might suffer from crashes or worse.
369		518
370	This function allows your callbacks to block by executing them in another	519	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	524	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
376	creating event callbacks that want to block.	525	creating event callbacks that want to block.
377		526
378	=cut	527	=cut
379		528
380	our @unblock_pool;
381	our @unblock_queue;	529	our @unblock_queue;
382	our $UNBLOCK_POOL_SIZE = 2;
383		530
384	sub unblock_handler_ {	531	# we create a special coro because we want to cede,
385	while () {	532	# to reduce pressure on the coro pool (because most callbacks
386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	533	# return immediately and can be reused) and because we cannot cede
387	$cb->(@arg);	534	# 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 {	535	our $unblock_scheduler = async {
		536	$current->desc ("[unblock_sub scheduler]");
396	while () {	537	while () {
397	while (my $cb = pop @unblock_queue) {	538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	540	my $coro = (pop @pool or new Coro \&pool_handler);
399	$handler->{arg} = $cb;	541
		542	$coro->{_invoke} = $cb;
400	$handler->ready;	543	$coro->ready;
401	cede;	544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
402	}	545	}
403		546	schedule; # sleep well
404	schedule;
405	}	547	}
406	};	548	};
407		549
408	sub unblock_sub(&) {	550	sub unblock_sub(&) {
409	my $cb = shift;	551	my $cb = shift;
410		552
411	sub {	553	sub {
412	push @unblock_queue, [$cb, @_];	554	unshift @unblock_queue, [$cb, @_];
413	$unblock_scheduler->ready;	555	$unblock_scheduler->ready;
414	}	556	}
415	}	557	}
416		558
417	=back	559	=back
…		…
424		566
425	- you must make very sure that no coro is still active on global	567	- you must make very sure that no coro is still active on global
426	destruction. very bad things might happen otherwise (usually segfaults).	568	destruction. very bad things might happen otherwise (usually segfaults).
427		569
428	- this module is not thread-safe. You should only ever use this module	570	- 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	571	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	572	to allow per-thread schedulers, but Coro::State does not yet allow
431	this).	573	this).
432		574
433	=head1 SEE ALSO	575	=head1 SEE ALSO
434		576

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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 1.129 by root, Wed Sep 19 22:33:08 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC