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

Comparing Coro/Coro.pm (file contents):
Revision 1.94 by root, Sat Dec 2 18:01:30 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 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 $VERSION = '3.8';
47		56
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
		117
		118	$main->{desc} = "[main::]";
108		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	$main->{specific} = $current->{specific}	121	$main->{specific} = $current->{specific}
111	if $current;	122	if $current;
112		123
…		…
128	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively.
129		140
130	=cut	141	=cut
131		142
132	$idle = sub {	143	$idle = sub {
133	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
134	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
135	};	146	};
		147
		148	sub _cancel {
		149	my ($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 $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	sub _do_trace_sub {
		161	&{$current->{_trace_sub_cb}}
		162	}
		163
		164	sub _do_trace_line {
		165	&{$current->{_trace_line_cb}}
		166	}
136		167
137	# this coroutine is necessary because a coroutine	168	# this coroutine is necessary because a coroutine
138	# cannot destroy itself.	169	# cannot destroy itself.
139	my @destroy;	170	my @destroy;
		171	my $manager;
		172
140	my $manager; $manager = new Coro sub {	173	$manager = new Coro sub {
141	while () {	174	while () {
142	# by overwriting the state object with the manager we destroy it	175	(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) {	176	while @destroy;
148	my $coro = pop @destroy;
149	$coro->{status} \|\|= [];
150	$_->ready for @{delete $coro->{join} \|\| []};
151		177
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;	178	&schedule;
159	}	179	}
160	};	180	};
		181	$manager->desc ("[coro manager]");
		182	$manager->prio (PRIO_MAX);
161		183
162	# static methods. not really.	184	# static methods. not really.
163		185
164	=back	186	=back
165		187
…		…
173		195
174	Create a new asynchronous coroutine and return it's coroutine object	196	Create a new asynchronous coroutine and return it's coroutine object
175	(usually unused). When the sub returns the new coroutine is automatically	197	(usually unused). When the sub returns the new coroutine is automatically
176	terminated.	198	terminated.
177		199
178	Calling C<exit> in a coroutine will not work correctly, so do not do that.	200	Calling C<exit> in a coroutine will do the same as calling exit outside
179		201	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	202	just as it would in the main program.
181	program.
182		203
183	# create a new coroutine that just prints its arguments	204	# create a new coroutine that just prints its arguments
184	async {	205	async {
185	print "@_\n";	206	print "@_\n";
186	} 1,2,3,4;	207	} 1,2,3,4;
187		208
188	=cut	209	=cut
189		210
190	sub async(&@) {	211	sub async(&@) {
191	my $pid = new Coro @_;	212	my $coro = new Coro @_;
192	$pid->ready;	213	$coro->ready;
193	$pid	214	$coro
		215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join (although you are allowed to), and you get a coroutine
		221	that might have executed other code already (which can be good or bad :).
		222
		223	Also, the block is executed in an C<eval> context and a warning will be
		224	issued in case of an exception instead of terminating the program, as
		225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		226	will not work in the expected way, unless you call terminate or cancel,
		227	which somehow defeats the purpose of pooling.
		228
		229	The priority will be reset to C<0> after each job, otherwise the coroutine
		230	will be re-used "as-is".
		231
		232	The pool size is limited to 8 idle coroutines (this can be adjusted by
		233	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		234	required.
		235
		236	If you are concerned about pooled coroutines growing a lot because a
		237	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		238	{ terminate }> once per second or so to slowly replenish the pool. In
		239	addition to that, when the stacks used by a handler grows larger than 16kb
		240	(adjustable with $Coro::POOL_RSS) it will also exit.
		241
		242	=cut
		243
		244	our $POOL_SIZE = 8;
		245	our $POOL_RSS = 16 * 1024;
		246	our @async_pool;
		247
		248	sub pool_handler {
		249	my $cb;
		250
		251	while () {
		252	eval {
		253	while () {
		254	_pool_1 $cb;
		255	&$cb;
		256	_pool_2 $cb;
		257	&schedule;
		258	}
		259	};
		260
		261	last if $@ eq "\3terminate\2\n";
		262	warn $@ if $@;
		263	}
		264	}
		265
		266	sub async_pool(&@) {
		267	# this is also inlined into the unlock_scheduler
		268	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		269
		270	$coro->{_invoke} = [@_];
		271	$coro->ready;
		272
		273	$coro
194	}	274	}
195		275
196	=item schedule	276	=item schedule
197		277
198	Calls the scheduler. Please note that the current coroutine will not be put	278	Calls the scheduler. Please note that the current coroutine will not be put
…		…
211	# wake up sleeping coroutine	291	# wake up sleeping coroutine
212	$current->ready;	292	$current->ready;
213	undef $current;	293	undef $current;
214	};	294	};
215		295
216	# call schedule until event occured.	296	# call schedule until event occurred.
217	# in case we are woken up for other reasons	297	# in case we are woken up for other reasons
218	# (current still defined), loop.	298	# (current still defined), loop.
219	Coro::schedule while $current;	299	Coro::schedule while $current;
220	}	300	}
221		301
222	=item cede	302	=item cede
223		303
224	"Cede" to other coroutines. This function puts the current coroutine into the	304	"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	305	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.	306	current "timeslice" to other coroutines of the same or higher priority.
		307
		308	Returns true if at least one coroutine switch has happened.
		309
		310	=item Coro::cede_notself
		311
		312	Works like cede, but is not exported by default and will cede to any
		313	coroutine, regardless of priority, once.
		314
		315	Returns true if at least one coroutine switch has happened.
227		316
228	=item terminate [arg...]	317	=item terminate [arg...]
229		318
230	Terminates the current coroutine with the given status values (see L<cancel>).	319	Terminates the current coroutine with the given status values (see L<cancel>).
231		320
…		…
250	Create a new coroutine and return it. When the sub returns the coroutine	339	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	340	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	341	called. To make the coroutine run you must first put it into the ready queue
253	by calling the ready method.	342	by calling the ready method.
254		343
255	Calling C<exit> in a coroutine will not work correctly, so do not do that.	344	See C<async> for additional discussion.
256		345
257	=cut	346	=cut
258		347
259	sub _run_coro {	348	sub _run_coro {
260	terminate &{+shift};	349	terminate &{+shift};
…		…
277	Return wether the coroutine is currently the ready queue or not,	366	Return wether the coroutine is currently the ready queue or not,
278		367
279	=item $coroutine->cancel (arg...)	368	=item $coroutine->cancel (arg...)
280		369
281	Terminates the given coroutine and makes it return the given arguments as	370	Terminates the given coroutine and makes it return the given arguments as
282	status (default: the empty list).	371	status (default: the empty list). Never returns if the coroutine is the
		372	current coroutine.
283		373
284	=cut	374	=cut
285		375
286	sub cancel {	376	sub cancel {
287	my $self = shift;	377	my $self = shift;
288	$self->{status} = [@_];	378	$self->{status} = [@_];
		379
		380	if ($current == $self) {
289	push @destroy, $self;	381	push @destroy, $self;
290	$manager->ready;	382	$manager->ready;
291	&schedule if $current == $self;	383	&schedule while 1;
		384	} else {
		385	$self->_cancel;
		386	}
292	}	387	}
293		388
294	=item $coroutine->join	389	=item $coroutine->join
295		390
296	Wait until the coroutine terminates and return any values given to the	391	Wait until the coroutine terminates and return any values given to the
…		…
299		394
300	=cut	395	=cut
301		396
302	sub join {	397	sub join {
303	my $self = shift;	398	my $self = shift;
		399
304	unless ($self->{status}) {	400	unless ($self->{status}) {
305	push @{$self->{join}}, $current;	401	my $current = $current;
306	&schedule;	402
		403	push @{$self->{destroy_cb}}, sub {
		404	$current->ready;
		405	undef $current;
		406	};
		407
		408	&schedule while $current;
307	}	409	}
		410
308	wantarray ? @{$self->{status}} : $self->{status}[0];	411	wantarray ? @{$self->{status}} : $self->{status}[0];
		412	}
		413
		414	=item $coroutine->on_destroy (\&cb)
		415
		416	Registers a callback that is called when this coroutine gets destroyed,
		417	but before it is joined. The callback gets passed the terminate arguments,
		418	if any.
		419
		420	=cut
		421
		422	sub on_destroy {
		423	my ($self, $cb) = @_;
		424
		425	push @{ $self->{destroy_cb} }, $cb;
309	}	426	}
310		427
311	=item $oldprio = $coroutine->prio ($newprio)	428	=item $oldprio = $coroutine->prio ($newprio)
312		429
313	Sets (or gets, if the argument is missing) the priority of the	430	Sets (or gets, if the argument is missing) the priority of the
…		…
348	$old;	465	$old;
349	}	466	}
350		467
351	=back	468	=back
352		469
353	=head2 UTILITY FUNCTIONS	470	=head2 GLOBAL FUNCTIONS
354		471
355	=over 4	472	=over 4
		473
		474	=item Coro::nready
		475
		476	Returns the number of coroutines that are currently in the ready state,
		477	i.e. that can be switched to. The value C<0> means that the only runnable
		478	coroutine is the currently running one, so C<cede> would have no effect,
		479	and C<schedule> would cause a deadlock unless there is an idle handler
		480	that wakes up some coroutines.
		481
		482	=item my $guard = Coro::guard { ... }
		483
		484	This creates and returns a guard object. Nothing happens until the object
		485	gets destroyed, in which case the codeblock given as argument will be
		486	executed. This is useful to free locks or other resources in case of a
		487	runtime error or when the coroutine gets canceled, as in both cases the
		488	guard block will be executed. The guard object supports only one method,
		489	C<< ->cancel >>, which will keep the codeblock from being executed.
		490
		491	Example: set some flag and clear it again when the coroutine gets canceled
		492	or the function returns:
		493
		494	sub do_something {
		495	my $guard = Coro::guard { $busy = 0 };
		496	$busy = 1;
		497
		498	# do something that requires $busy to be true
		499	}
		500
		501	=cut
		502
		503	sub guard(&) {
		504	bless \(my $cb = $_[0]), "Coro::guard"
		505	}
		506
		507	sub Coro::guard::cancel {
		508	${$_[0]} = sub { };
		509	}
		510
		511	sub Coro::guard::DESTROY {
		512	${$_[0]}->();
		513	}
		514
356		515
357	=item unblock_sub { ... }	516	=item unblock_sub { ... }
358		517
359	This utility function takes a BLOCK or code reference and "unblocks" it,	518	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	519	returning the new coderef. This means that the new coderef will return
361	immediately without blocking, returning nothing, while the original code	520	immediately without blocking, returning nothing, while the original code
362	ref will be called (with parameters) from within its own coroutine.	521	ref will be called (with parameters) from within its own coroutine.
363		522
364	The reason this fucntion exists is that many event libraries (such as the	523	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	524	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,	525	of thread-safety). This means you must not block within event callbacks,
367	otherwise you might suffer from crashes or worse.	526	otherwise you might suffer from crashes or worse.
368		527
369	This function allows your callbacks to block by executing them in another	528	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	533	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
375	creating event callbacks that want to block.	534	creating event callbacks that want to block.
376		535
377	=cut	536	=cut
378		537
379	our @unblock_pool;
380	our @unblock_queue;	538	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		539
383	sub unblock_handler_ {	540	# we create a special coro because we want to cede,
384	while () {	541	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	542	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	543	# 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 {	544	our $unblock_scheduler = new Coro sub {
395	while () {	545	while () {
396	while (my $cb = pop @unblock_queue) {	546	while (my $cb = pop @unblock_queue) {
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	547	# this is an inlined copy of async_pool
398	$handler->{arg} = $cb;	548	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		549
		550	$coro->{_invoke} = $cb;
399	$handler->ready;	551	$coro->ready;
400	cede;	552	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	553	}
402		554	schedule; # sleep well
403	schedule;
404	}	555	}
405	};	556	};
		557	$unblock_scheduler->desc ("[unblock_sub scheduler]");
406		558
407	sub unblock_sub(&) {	559	sub unblock_sub(&) {
408	my $cb = shift;	560	my $cb = shift;
409		561
410	sub {	562	sub {
411	push @unblock_queue, [$cb, @_];	563	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	564	$unblock_scheduler->ready;
413	}	565	}
414	}	566	}
415		567
416	=back	568	=back
…		…
423		575
424	- you must make very sure that no coro is still active on global	576	- you must make very sure that no coro is still active on global
425	destruction. very bad things might happen otherwise (usually segfaults).	577	destruction. very bad things might happen otherwise (usually segfaults).
426		578
427	- this module is not thread-safe. You should only ever use this module	579	- 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	580	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	581	to allow per-thread schedulers, but Coro::State does not yet allow
430	this).	582	this).
431		583
432	=head1 SEE ALSO	584	=head1 SEE ALSO
433		585

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Comparing Coro/Coro.pm (file contents): Revision 1.94 by root, Sat Dec 2 18:01:30 2006 UTC vs. Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.94 by root, Sat Dec 2 18:01:30 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC