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

Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.108 by root, Fri Jan 5 20:00:49 2007 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
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 use din this module also
		26	guarentees 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 $VERSION = '3.3';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($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	# process itself intact (we basically make it a zombie
155	# process that always runs the manager thread, so it's possible
156	# to transfer() to this process).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	168	&schedule;
160	}	169	}
161	};	170	};
162		171
		172	$manager->prio (PRIO_MAX);
		173
163	# static methods. not really.	174	# static methods. not really.
164		175
165	=back	176	=back
166		177
167	=head2 STATIC METHODS	178	=head2 STATIC METHODS
168		179
169	Static methods are actually functions that operate on the current process only.	180	Static methods are actually functions that operate on the current coroutine only.
170		181
171	=over 4	182	=over 4
172		183
173	=item async { ... } [@args...]	184	=item async { ... } [@args...]
174		185
175	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new process 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 not work correctly, so do not do that.
180		191
181	When the coroutine dies, the program will exit, just as in the main	192	When the coroutine dies, the program will exit, just as in the main
…		…
187	} 1,2,3,4;	198	} 1,2,3,4;
188		199
189	=cut	200	=cut
190		201
191	sub async(&@) {	202	sub async(&@) {
192	my $pid = new Coro @_;	203	my $coro = new Coro @_;
193	$pid->ready;	204	$coro->ready;
194	$pid	205	$coro
		206	}
		207
		208	=item async_pool { ... } [@args...]
		209
		210	Similar to C<async>, but uses a coroutine pool, so you should not call
		211	terminate or join (although you are allowed to), and you get a coroutine
		212	that might have executed other code already (which can be good or bad :).
		213
		214	Also, the block is executed in an C<eval> context and a warning will be
		215	issued in case of an exception instead of terminating the program, as
		216	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		217	will not work in the expected way, unless you call terminate or cancel,
		218	which somehow defeats the purpose of pooling.
		219
		220	The priority will be reset to C<0> after each job, otherwise the coroutine
		221	will be re-used "as-is".
		222
		223	The pool size is limited to 8 idle coroutines (this can be adjusted by
		224	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		225	required.
		226
		227	If you are concerned about pooled coroutines growing a lot because a
		228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		229	terminate }> once per second or so to slowly replenish the pool.
		230
		231	=cut
		232
		233	our $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	my ($cb, @arg) = @{ delete $current->{_invoke} };
		239
		240	eval {
		241	$cb->(@arg);
		242	};
		243	warn $@ if $@;
		244
		245	last if @pool >= $POOL_SIZE;
		246	push @pool, $current;
		247
		248	$current->prio (0);
		249	schedule;
		250	}
		251	}
		252
		253	sub async_pool(&@) {
		254	# this is also inlined into the unlock_scheduler
		255	my $coro = (pop @pool or new Coro \&pool_handler);
		256
		257	$coro->{_invoke} = [@_];
		258	$coro->ready;
		259
		260	$coro
195	}	261	}
196		262
197	=item schedule	263	=item schedule
198		264
199	Calls the scheduler. Please note that the current process will not be put	265	Calls the scheduler. Please note that the current coroutine will not be put
200	into the ready queue, so calling this function usually means you will	266	into the ready queue, so calling this function usually means you will
201	never be called again unless something else (e.g. an event handler) calls	267	never be called again unless something else (e.g. an event handler) calls
202	ready.	268	ready.
203		269
204	The canonical way to wait on external events is this:	270	The canonical way to wait on external events is this:
205		271
206	{	272	{
207	# remember current process	273	# remember current coroutine
208	my $current = $Coro::current;	274	my $current = $Coro::current;
209		275
210	# register a hypothetical event handler	276	# register a hypothetical event handler
211	on_event_invoke sub {	277	on_event_invoke sub {
212	# wake up sleeping coroutine	278	# wake up sleeping coroutine
…		…
218	# in case we are woken up for other reasons	284	# in case we are woken up for other reasons
219	# (current still defined), loop.	285	# (current still defined), loop.
220	Coro::schedule while $current;	286	Coro::schedule while $current;
221	}	287	}
222		288
223	=cut
224
225	=item cede	289	=item cede
226		290
227	"Cede" to other processes. This function puts the current process into the	291	"Cede" to other coroutines. This function puts the current coroutine into the
228	ready queue and calls C<schedule>, which has the effect of giving up the	292	ready queue and calls C<schedule>, which has the effect of giving up the
229	current "timeslice" to other coroutines of the same or higher priority.	293	current "timeslice" to other coroutines of the same or higher priority.
230		294
231	=cut	295	Returns true if at least one coroutine switch has happened.
		296
		297	=item Coro::cede_notself
		298
		299	Works like cede, but is not exported by default and will cede to any
		300	coroutine, regardless of priority, once.
		301
		302	Returns true if at least one coroutine switch has happened.
232		303
233	=item terminate [arg...]	304	=item terminate [arg...]
234		305
235	Terminates the current process with the given status values (see L<cancel>).	306	Terminates the current coroutine with the given status values (see L<cancel>).
236		307
237	=cut	308	=cut
238		309
239	sub terminate {	310	sub terminate {
240	$current->cancel (@_);	311	$current->cancel (@_);
…		…
242		313
243	=back	314	=back
244		315
245	# dynamic methods	316	# dynamic methods
246		317
247	=head2 PROCESS METHODS	318	=head2 COROUTINE METHODS
248		319
249	These are the methods you can call on process objects.	320	These are the methods you can call on coroutine objects.
250		321
251	=over 4	322	=over 4
252		323
253	=item new Coro \&sub [, @args...]	324	=item new Coro \&sub [, @args...]
254		325
255	Create a new process and return it. When the sub returns the process	326	Create a new coroutine and return it. When the sub returns the coroutine
256	automatically terminates as if C<terminate> with the returned values were	327	automatically terminates as if C<terminate> with the returned values were
257	called. To make the process run you must first put it into the ready queue	328	called. To make the coroutine run you must first put it into the ready queue
258	by calling the ready method.	329	by calling the ready method.
259		330
260	Calling C<exit> in a coroutine will not work correctly, so do not do that.	331	Calling C<exit> in a coroutine will not work correctly, so do not do that.
261		332
262	=cut	333	=cut
263		334
264	sub _new_coro {	335	sub _run_coro {
265	terminate &{+shift};	336	terminate &{+shift};
266	}	337	}
267		338
268	sub new {	339	sub new {
269	my $class = shift;	340	my $class = shift;
270		341
271	$class->SUPER::new (\&_new_coro, @_)	342	$class->SUPER::new (\&_run_coro, @_)
272	}	343	}
273		344
274	=item $success = $process->ready	345	=item $success = $coroutine->ready
275		346
276	Put the given process into the ready queue (according to it's priority)	347	Put the given coroutine into the ready queue (according to it's priority)
277	and return true. If the process is already in the ready queue, do nothing	348	and return true. If the coroutine is already in the ready queue, do nothing
278	and return false.	349	and return false.
279		350
280	=item $is_ready = $process->is_ready	351	=item $is_ready = $coroutine->is_ready
281		352
282	Return wether the process is currently the ready queue or not,	353	Return wether the coroutine is currently the ready queue or not,
283		354
284	=item $process->cancel (arg...)	355	=item $coroutine->cancel (arg...)
285		356
286	Terminates the given process and makes it return the given arguments as	357	Terminates the given coroutine and makes it return the given arguments as
287	status (default: the empty list).	358	status (default: the empty list). Never returns if the coroutine is the
		359	current coroutine.
288		360
289	=cut	361	=cut
290		362
291	sub cancel {	363	sub cancel {
292	my $self = shift;	364	my $self = shift;
293	$self->{status} = [@_];	365	$self->{status} = [@_];
		366
		367	if ($current == $self) {
294	push @destroy, $self;	368	push @destroy, $self;
295	$manager->ready;	369	$manager->ready;
296	&schedule if $current == $self;	370	&schedule while 1;
		371	} else {
		372	$self->_cancel;
		373	}
297	}	374	}
298		375
299	=item $process->join	376	=item $coroutine->join
300		377
301	Wait until the coroutine terminates and return any values given to the	378	Wait until the coroutine terminates and return any values given to the
302	C<terminate> or C<cancel> functions. C<join> can be called multiple times	379	C<terminate> or C<cancel> functions. C<join> can be called multiple times
303	from multiple processes.	380	from multiple coroutine.
304		381
305	=cut	382	=cut
306		383
307	sub join {	384	sub join {
308	my $self = shift;	385	my $self = shift;
		386
309	unless ($self->{status}) {	387	unless ($self->{status}) {
310	push @{$self->{join}}, $current;	388	my $current = $current;
311	&schedule;	389
		390	push @{$self->{destroy_cb}}, sub {
		391	$current->ready;
		392	undef $current;
		393	};
		394
		395	&schedule while $current;
312	}	396	}
		397
313	wantarray ? @{$self->{status}} : $self->{status}[0];	398	wantarray ? @{$self->{status}} : $self->{status}[0];
314	}	399	}
315		400
		401	=item $coroutine->on_destroy (\&cb)
		402
		403	Registers a callback that is called when this coroutine gets destroyed,
		404	but before it is joined. The callback gets passed the terminate arguments,
		405	if any.
		406
		407	=cut
		408
		409	sub on_destroy {
		410	my ($self, $cb) = @_;
		411
		412	push @{ $self->{destroy_cb} }, $cb;
		413	}
		414
316	=item $oldprio = $process->prio ($newprio)	415	=item $oldprio = $coroutine->prio ($newprio)
317		416
318	Sets (or gets, if the argument is missing) the priority of the	417	Sets (or gets, if the argument is missing) the priority of the
319	process. Higher priority processes get run before lower priority	418	coroutine. Higher priority coroutines get run before lower priority
320	processes. Priorities are small signed integers (currently -4 .. +3),	419	coroutines. Priorities are small signed integers (currently -4 .. +3),
321	that you can refer to using PRIO_xxx constants (use the import tag :prio	420	that you can refer to using PRIO_xxx constants (use the import tag :prio
322	to get then):	421	to get then):
323		422
324	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	423	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
325	3 > 1 > 0 > -1 > -3 > -4	424	3 > 1 > 0 > -1 > -3 > -4
…		…
328	current->prio(PRIO_HIGH);	427	current->prio(PRIO_HIGH);
329		428
330	The idle coroutine ($Coro::idle) always has a lower priority than any	429	The idle coroutine ($Coro::idle) always has a lower priority than any
331	existing coroutine.	430	existing coroutine.
332		431
333	Changing the priority of the current process will take effect immediately,	432	Changing the priority of the current coroutine will take effect immediately,
334	but changing the priority of processes in the ready queue (but not	433	but changing the priority of coroutines in the ready queue (but not
335	running) will only take effect after the next schedule (of that	434	running) will only take effect after the next schedule (of that
336	process). This is a bug that will be fixed in some future version.	435	coroutine). This is a bug that will be fixed in some future version.
337		436
338	=item $newprio = $process->nice ($change)	437	=item $newprio = $coroutine->nice ($change)
339		438
340	Similar to C<prio>, but subtract the given value from the priority (i.e.	439	Similar to C<prio>, but subtract the given value from the priority (i.e.
341	higher values mean lower priority, just as in unix).	440	higher values mean lower priority, just as in unix).
342		441
343	=item $olddesc = $process->desc ($newdesc)	442	=item $olddesc = $coroutine->desc ($newdesc)
344		443
345	Sets (or gets in case the argument is missing) the description for this	444	Sets (or gets in case the argument is missing) the description for this
346	process. This is just a free-form string you can associate with a process.	445	coroutine. This is just a free-form string you can associate with a coroutine.
347		446
348	=cut	447	=cut
349		448
350	sub desc {	449	sub desc {
351	my $old = $_[0]{desc};	450	my $old = $_[0]{desc};
…		…
353	$old;	452	$old;
354	}	453	}
355		454
356	=back	455	=back
357		456
		457	=head2 GLOBAL FUNCTIONS
		458
		459	=over 4
		460
		461	=item Coro::nready
		462
		463	Returns the number of coroutines that are currently in the ready state,
		464	i.e. that can be swicthed to. The value C<0> means that the only runnable
		465	coroutine is the currently running one, so C<cede> would have no effect,
		466	and C<schedule> would cause a deadlock unless there is an idle handler
		467	that wakes up some coroutines.
		468
		469	=item my $guard = Coro::guard { ... }
		470
		471	This creates and returns a guard object. Nothing happens until the objetc
		472	gets destroyed, in which case the codeblock given as argument will be
		473	executed. This is useful to free locks or other resources in case of a
		474	runtime error or when the coroutine gets canceled, as in both cases the
		475	guard block will be executed. The guard object supports only one method,
		476	C<< ->cancel >>, which will keep the codeblock from being executed.
		477
		478	Example: set some flag and clear it again when the coroutine gets canceled
		479	or the function returns:
		480
		481	sub do_something {
		482	my $guard = Coro::guard { $busy = 0 };
		483	$busy = 1;
		484
		485	# do something that requires $busy to be true
		486	}
		487
		488	=cut
		489
		490	sub guard(&) {
		491	bless \(my $cb = $_[0]), "Coro::guard"
		492	}
		493
		494	sub Coro::guard::cancel {
		495	${$_[0]} = sub { };
		496	}
		497
		498	sub Coro::guard::DESTROY {
		499	${$_[0]}->();
		500	}
		501
		502
		503	=item unblock_sub { ... }
		504
		505	This utility function takes a BLOCK or code reference and "unblocks" it,
		506	returning the new coderef. This means that the new coderef will return
		507	immediately without blocking, returning nothing, while the original code
		508	ref will be called (with parameters) from within its own coroutine.
		509
		510	The reason this fucntion exists is that many event libraries (such as the
		511	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		512	of thread-safety). This means you must not block within event callbacks,
		513	otherwise you might suffer from crashes or worse.
		514
		515	This function allows your callbacks to block by executing them in another
		516	coroutine where it is safe to block. One example where blocking is handy
		517	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		518	disk.
		519
		520	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		521	creating event callbacks that want to block.
		522
		523	=cut
		524
		525	our @unblock_queue;
		526
		527	# we create a special coro because we want to cede,
		528	# to reduce pressure on the coro pool (because most callbacks
		529	# return immediately and can be reused) and because we cannot cede
		530	# inside an event callback.
		531	our $unblock_scheduler = async {
		532	while () {
		533	while (my $cb = pop @unblock_queue) {
		534	# this is an inlined copy of async_pool
		535	my $coro = (pop @pool or new Coro \&pool_handler);
		536
		537	$coro->{_invoke} = $cb;
		538	$coro->ready;
		539	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		540	}
		541	schedule; # sleep well
		542	}
		543	};
		544
		545	sub unblock_sub(&) {
		546	my $cb = shift;
		547
		548	sub {
		549	unshift @unblock_queue, [$cb, @_];
		550	$unblock_scheduler->ready;
		551	}
		552	}
		553
		554	=back
		555
358	=cut	556	=cut
359		557
360	1;	558	1;
361		559
362	=head1 BUGS/LIMITATIONS	560	=head1 BUGS/LIMITATIONS

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs. Revision 1.108 by root, Fri Jan 5 20:00:49 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.108 by root, Fri Jan 5 20:00:49 2007 UTC