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

Comparing Coro/Coro.pm (file contents):
Revision 1.72 by root, Mon Dec 12 17:49:07 2005 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
35	use strict;	44	use strict;
36	no warnings "uninitialized";	45	no warnings "uninitialized";
37		46
38	use Coro::State;	47	use Coro::State;
39		48
40	use base Exporter::;	49	use base qw(Coro::State Exporter);
41		50
42	our $idle; # idle coroutine	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 = 1.51;	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;
…		…
95		104
96	$main = new Coro;	105	$main = new Coro;
97		106
98	=item $current (or as function: current)	107	=item $current (or as function: current)
99		108
100	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
101		115
102	=cut	116	=cut
103		117
104	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
105	if ($current) {
106	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
107	}	120	if $current;
108		121
109	$current = $main;	122	_set_current $main;
110		123
111	sub current() { $current }	124	sub current() { $current }
112		125
113	=item $idle	126	=item $idle
114		127
115	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
116	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
117		131
118	=cut	132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
119		135
120	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
121	$idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
122	print STDERR "FATAL: deadlock detected\n";	138
123	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
124	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
125		157
126	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
127	# cannot destroy itself.	159	# cannot destroy itself.
128	my @destroy;	160	my @destroy;
129	my $manager;	161	my $manager;
		162
130	$manager = new Coro sub {	163	$manager = new Coro sub {
131	while () {	164	while () {
132	# by overwriting the state object with the manager we destroy it	165	(shift @destroy)->_cancel
133	# while still being able to schedule this coroutine (in case it has
134	# been readied multiple times. this is harmless since the manager
135	# can be called as many times as neccessary and will always
136	# remove itself from the runqueue
137	while (@destroy) {	166	while @destroy;
138	my $coro = pop @destroy;
139	$coro->{status} \|\|= [];
140	$_->ready for @{delete $coro->{join} \|\| []};
141		167
142	# the next line destroys the _coro_state, but keeps the
143	# process itself intact (we basically make it a zombie
144	# process that always runs the manager thread, so it's possible
145	# to transfer() to this process).
146	$coro->{_coro_state} = $manager->{_coro_state};
147	}
148	&schedule;	168	&schedule;
149	}	169	}
150	};	170	};
151		171
		172	$manager->prio (PRIO_MAX);
		173
152	# static methods. not really.	174	# static methods. not really.
153		175
154	=back	176	=back
155		177
156	=head2 STATIC METHODS	178	=head2 STATIC METHODS
157		179
158	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.
159		181
160	=over 4	182	=over 4
161		183
162	=item async { ... } [@args...]	184	=item async { ... } [@args...]
163		185
164	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
165	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
166	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
167		194
168	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
169	async {	196	async {
170	print "@_\n";	197	print "@_\n";
171	} 1,2,3,4;	198	} 1,2,3,4;
172		199
173	=cut	200	=cut
174		201
175	sub async(&@) {	202	sub async(&@) {
176	my $pid = new Coro @_;	203	my $coro = new Coro @_;
177	$manager->ready; # this ensures that the stack is cloned from the manager
178	$pid->ready;	204	$coro->ready;
179	$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
180	}	261	}
181		262
182	=item schedule	263	=item schedule
183		264
184	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
185	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
186	never be called again.	267	never be called again unless something else (e.g. an event handler) calls
		268	ready.
187		269
188	=cut	270	The canonical way to wait on external events is this:
		271
		272	{
		273	# remember current coroutine
		274	my $current = $Coro::current;
		275
		276	# register a hypothetical event handler
		277	on_event_invoke sub {
		278	# wake up sleeping coroutine
		279	$current->ready;
		280	undef $current;
		281	};
		282
		283	# call schedule until event occured.
		284	# in case we are woken up for other reasons
		285	# (current still defined), loop.
		286	Coro::schedule while $current;
		287	}
189		288
190	=item cede	289	=item cede
191		290
192	"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
193	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
194	current "timeslice" to other coroutines of the same or higher priority.	293	current "timeslice" to other coroutines of the same or higher priority.
195		294
196	=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.
197		303
198	=item terminate [arg...]	304	=item terminate [arg...]
199		305
200	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>).
201		307
202	=cut	308	=cut
203		309
204	sub terminate {	310	sub terminate {
205	$current->cancel (@_);	311	$current->cancel (@_);
…		…
207		313
208	=back	314	=back
209		315
210	# dynamic methods	316	# dynamic methods
211		317
212	=head2 PROCESS METHODS	318	=head2 COROUTINE METHODS
213		319
214	These are the methods you can call on process objects.	320	These are the methods you can call on coroutine objects.
215		321
216	=over 4	322	=over 4
217		323
218	=item new Coro \&sub [, @args...]	324	=item new Coro \&sub [, @args...]
219		325
220	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
221	automatically terminates as if C<terminate> with the returned values were	327	automatically terminates as if C<terminate> with the returned values were
222	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
223	by calling the ready method.	329	by calling the ready method.
224		330
225	=cut	331	Calling C<exit> in a coroutine will not work correctly, so do not do that.
226		332
		333	=cut
		334
227	sub _newcoro {	335	sub _run_coro {
228	terminate &{+shift};	336	terminate &{+shift};
229	}	337	}
230		338
231	sub new {	339	sub new {
232	my $class = shift;	340	my $class = shift;
233	bless {
234	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
235	}, $class;
236	}
237		341
238	=item $process->ready	342	$class->SUPER::new (\&_run_coro, @_)
		343	}
239		344
240	Put the given process into the ready queue.	345	=item $success = $coroutine->ready
241		346
242	=cut	347	Put the given coroutine into the ready queue (according to it's priority)
		348	and return true. If the coroutine is already in the ready queue, do nothing
		349	and return false.
243		350
		351	=item $is_ready = $coroutine->is_ready
		352
		353	Return wether the coroutine is currently the ready queue or not,
		354
244	=item $process->cancel (arg...)	355	=item $coroutine->cancel (arg...)
245		356
246	Temrinates the given process and makes it return the given arguments as	357	Terminates the given coroutine and makes it return the given arguments as
247	status (default: the empty list).	358	status (default: the empty list). Never returns if the coroutine is the
		359	current coroutine.
248		360
249	=cut	361	=cut
250		362
251	sub cancel {	363	sub cancel {
252	my $self = shift;	364	my $self = shift;
253	$self->{status} = [@_];	365	$self->{status} = [@_];
		366
		367	if ($current == $self) {
254	push @destroy, $self;	368	push @destroy, $self;
255	$manager->ready;	369	$manager->ready;
256	&schedule if $current == $self;	370	&schedule while 1;
		371	} else {
		372	$self->_cancel;
		373	}
257	}	374	}
258		375
259	=item $process->join	376	=item $coroutine->join
260		377
261	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
262	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
263	from multiple processes.	380	from multiple coroutine.
264		381
265	=cut	382	=cut
266		383
267	sub join {	384	sub join {
268	my $self = shift;	385	my $self = shift;
		386
269	unless ($self->{status}) {	387	unless ($self->{status}) {
270	push @{$self->{join}}, $current;	388	my $current = $current;
271	&schedule;	389
		390	push @{$self->{destroy_cb}}, sub {
		391	$current->ready;
		392	undef $current;
		393	};
		394
		395	&schedule while $current;
272	}	396	}
		397
273	wantarray ? @{$self->{status}} : $self->{status}[0];	398	wantarray ? @{$self->{status}} : $self->{status}[0];
274	}	399	}
275		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
276	=item $oldprio = $process->prio($newprio)	415	=item $oldprio = $coroutine->prio ($newprio)
277		416
278	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
279	process. Higher priority processes get run before lower priority	418	coroutine. Higher priority coroutines get run before lower priority
280	processes. Priorities are small signed integers (currently -4 .. +3),	419	coroutines. Priorities are small signed integers (currently -4 .. +3),
281	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
282	to get then):	421	to get then):
283		422
284	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
285	3 > 1 > 0 > -1 > -3 > -4	424	3 > 1 > 0 > -1 > -3 > -4
…		…
288	current->prio(PRIO_HIGH);	427	current->prio(PRIO_HIGH);
289		428
290	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
291	existing coroutine.	430	existing coroutine.
292		431
293	Changing the priority of the current process will take effect immediately,	432	Changing the priority of the current coroutine will take effect immediately,
294	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
295	running) will only take effect after the next schedule (of that	434	running) will only take effect after the next schedule (of that
296	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.
297		436
298	=cut
299
300	sub prio {
301	my $old = $_[0]{prio};
302	$_[0]{prio} = $_[1] if @_ > 1;
303	$old;
304	}
305
306	=item $newprio = $process->nice($change)	437	=item $newprio = $coroutine->nice ($change)
307		438
308	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.
309	higher values mean lower priority, just as in unix).	440	higher values mean lower priority, just as in unix).
310		441
311	=cut
312
313	sub nice {
314	$_[0]{prio} -= $_[1];
315	}
316
317	=item $olddesc = $process->desc($newdesc)	442	=item $olddesc = $coroutine->desc ($newdesc)
318		443
319	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
320	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.
321		446
322	=cut	447	=cut
323		448
324	sub desc {	449	sub desc {
325	my $old = $_[0]{desc};	450	my $old = $_[0]{desc};
…		…
327	$old;	452	$old;
328	}	453	}
329		454
330	=back	455	=back
331		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
332	=cut	556	=cut
333		557
334	1;	558	1;
335		559
336	=head1 BUGS/LIMITATIONS	560	=head1 BUGS/LIMITATIONS

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Comparing Coro/Coro.pm (file contents): Revision 1.72 by root, Mon Dec 12 17:49:07 2005 UTC vs. Revision 1.108 by root, Fri Jan 5 20:00:49 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.72 by root, Mon Dec 12 17:49:07 2005 UTC vs.
Revision 1.108 by root, Fri Jan 5 20:00:49 2007 UTC