[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 1.129 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 = '3.01';	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 {
		164	$current->desc ("[coro manager]");
		165
141	while () {	166	while () {
142	# by overwriting the state object with the manager we destroy it	167	(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) {	168	while @destroy;
148	my $coro = pop @destroy;
149	$coro->{status} \|\|= [];
150	$_->ready for @{delete $coro->{join} \|\| []};
151		169
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;	170	&schedule;
159	}	171	}
160	};	172	};
		173
		174	$manager->prio (PRIO_MAX);
161		175
162	# static methods. not really.	176	# static methods. not really.
163		177
164	=back	178	=back
165		179
…		…
173		187
174	Create a new asynchronous coroutine and return it's coroutine object	188	Create a new asynchronous coroutine and return it's coroutine object
175	(usually unused). When the sub returns the new coroutine is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
176	terminated.	190	terminated.
177		191
178	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
179		193	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	194	just as it would in the main program.
181	program.
182		195
183	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
184	async {	197	async {
185	print "@_\n";	198	print "@_\n";
186	} 1,2,3,4;	199	} 1,2,3,4;
187		200
188	=cut	201	=cut
189		202
190	sub async(&@) {	203	sub async(&@) {
191	my $pid = new Coro @_;	204	my $coro = new Coro @_;
192	$pid->ready;	205	$coro->ready;
193	$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
194	}	265	}
195		266
196	=item schedule	267	=item schedule
197		268
198	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
…		…
211	# wake up sleeping coroutine	282	# wake up sleeping coroutine
212	$current->ready;	283	$current->ready;
213	undef $current;	284	undef $current;
214	};	285	};
215		286
216	# call schedule until event occured.	287	# call schedule until event occurred.
217	# in case we are woken up for other reasons	288	# in case we are woken up for other reasons
218	# (current still defined), loop.	289	# (current still defined), loop.
219	Coro::schedule while $current;	290	Coro::schedule while $current;
220	}	291	}
221		292
222	=item cede	293	=item cede
223		294
224	"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
225	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
226	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.
227		307
228	=item terminate [arg...]	308	=item terminate [arg...]
229		309
230	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>).
231		311
…		…
250	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
251	automatically terminates as if C<terminate> with the returned values were	331	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	332	called. To make the coroutine run you must first put it into the ready queue
253	by calling the ready method.	333	by calling the ready method.
254		334
255	Calling C<exit> in a coroutine will not work correctly, so do not do that.	335	See C<async> for additional discussion.
256		336
257	=cut	337	=cut
258		338
259	sub _run_coro {	339	sub _run_coro {
260	terminate &{+shift};	340	terminate &{+shift};
…		…
277	Return wether the coroutine is currently the ready queue or not,	357	Return wether the coroutine is currently the ready queue or not,
278		358
279	=item $coroutine->cancel (arg...)	359	=item $coroutine->cancel (arg...)
280		360
281	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
282	status (default: the empty list).	362	status (default: the empty list). Never returns if the coroutine is the
		363	current coroutine.
283		364
284	=cut	365	=cut
285		366
286	sub cancel {	367	sub cancel {
287	my $self = shift;	368	my $self = shift;
288	$self->{status} = [@_];	369	$self->{status} = [@_];
		370
		371	if ($current == $self) {
289	push @destroy, $self;	372	push @destroy, $self;
290	$manager->ready;	373	$manager->ready;
291	&schedule if $current == $self;	374	&schedule while 1;
		375	} else {
		376	$self->_cancel;
		377	}
292	}	378	}
293		379
294	=item $coroutine->join	380	=item $coroutine->join
295		381
296	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
…		…
299		385
300	=cut	386	=cut
301		387
302	sub join {	388	sub join {
303	my $self = shift;	389	my $self = shift;
		390
304	unless ($self->{status}) {	391	unless ($self->{status}) {
305	push @{$self->{join}}, $current;	392	my $current = $current;
306	&schedule;	393
		394	push @{$self->{destroy_cb}}, sub {
		395	$current->ready;
		396	undef $current;
		397	};
		398
		399	&schedule while $current;
307	}	400	}
		401
308	wantarray ? @{$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;
309	}	417	}
310		418
311	=item $oldprio = $coroutine->prio ($newprio)	419	=item $oldprio = $coroutine->prio ($newprio)
312		420
313	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
…		…
348	$old;	456	$old;
349	}	457	}
350		458
351	=back	459	=back
352		460
353	=head2 UTILITY FUNCTIONS	461	=head2 GLOBAL FUNCTIONS
354		462
355	=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
356		506
357	=item unblock_sub { ... }	507	=item unblock_sub { ... }
358		508
359	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,
360	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
361	immediately without blocking, returning nothing, while the original code	511	immediately without blocking, returning nothing, while the original code
362	ref will be called (with parameters) from within its own coroutine.	512	ref will be called (with parameters) from within its own coroutine.
363		513
364	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
365	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
366	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,
367	otherwise you might suffer from crashes or worse.	517	otherwise you might suffer from crashes or worse.
368		518
369	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
…		…
374	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
375	creating event callbacks that want to block.	525	creating event callbacks that want to block.
376		526
377	=cut	527	=cut
378		528
379	our @unblock_pool;
380	our @unblock_queue;	529	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		530
383	sub unblock_handler_ {	531	# we create a special coro because we want to cede,
384	while () {	532	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	533	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	534	# 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 {	535	our $unblock_scheduler = async {
		536	$current->desc ("[unblock_sub scheduler]");
395	while () {	537	while () {
396	while (my $cb = pop @unblock_queue) {	538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	540	my $coro = (pop @pool or new Coro \&pool_handler);
398	$handler->{arg} = $cb;	541
		542	$coro->{_invoke} = $cb;
399	$handler->ready;	543	$coro->ready;
400	cede;	544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	545	}
402		546	schedule; # sleep well
403	schedule;
404	}	547	}
405	};	548	};
406		549
407	sub unblock_sub(&) {	550	sub unblock_sub(&) {
408	my $cb = shift;	551	my $cb = shift;
409		552
410	sub {	553	sub {
411	push @unblock_queue, [$cb, @_];	554	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	555	$unblock_scheduler->ready;
413	}	556	}
414	}	557	}
415		558
416	=back	559	=back
…		…
423		566
424	- 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
425	destruction. very bad things might happen otherwise (usually segfaults).	568	destruction. very bad things might happen otherwise (usually segfaults).
426		569
427	- 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
428	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
429	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
430	this).	573	this).
431		574
432	=head1 SEE ALSO	575	=head1 SEE ALSO
433		576

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Comparing Coro/Coro.pm (file contents): Revision 1.96 by root, Mon Dec 4 03:48:16 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 1.96 by root, Mon Dec 4 03:48:16 2006 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC