[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 1.125 by root, Fri Apr 27 19:35:58 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 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 $VERSION = '3.62';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
99		108
100	The current coroutine (the last coroutine switched to). The initial value	109	The current coroutine (the last coroutine switched to). The initial value
101	is C<$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 {
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 do the same as calling exit outside
180		191	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	192	just as it would in the main program.
182	program.
183		193
184	# create a new coroutine that just prints its arguments	194	# create a new coroutine that just prints its arguments
185	async {	195	async {
186	print "@_\n";	196	print "@_\n";
187	} 1,2,3,4;	197	} 1,2,3,4;
188		198
189	=cut	199	=cut
190		200
191	sub async(&@) {	201	sub async(&@) {
192	my $pid = new Coro @_;	202	my $coro = new Coro @_;
193	$pid->ready;	203	$coro->ready;
194	$pid	204	$coro
		205	}
		206
		207	=item async_pool { ... } [@args...]
		208
		209	Similar to C<async>, but uses a coroutine pool, so you should not call
		210	terminate or join (although you are allowed to), and you get a coroutine
		211	that might have executed other code already (which can be good or bad :).
		212
		213	Also, the block is executed in an C<eval> context and a warning will be
		214	issued in case of an exception instead of terminating the program, as
		215	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		216	will not work in the expected way, unless you call terminate or cancel,
		217	which somehow defeats the purpose of pooling.
		218
		219	The priority will be reset to C<0> after each job, otherwise the coroutine
		220	will be re-used "as-is".
		221
		222	The pool size is limited to 8 idle coroutines (this can be adjusted by
		223	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		224	required.
		225
		226	If you are concerned about pooled coroutines growing a lot because a
		227	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		228	terminate }> once per second or so to slowly replenish the pool.
		229
		230	=cut
		231
		232	our $POOL_SIZE = 8;
		233	our @pool;
		234
		235	sub pool_handler {
		236	while () {
		237	eval {
		238	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		239	$cb->(@arg);
		240	};
		241	warn $@ if $@;
		242
		243	last if @pool >= $POOL_SIZE;
		244	push @pool, $current;
		245
		246	$current->save (Coro::State::SAVE_DEF);
		247	$current->prio (0);
		248	schedule;
		249	}
		250	}
		251
		252	sub async_pool(&@) {
		253	# this is also inlined into the unlock_scheduler
		254	my $coro = (pop @pool or new Coro \&pool_handler);
		255
		256	$coro->{_invoke} = [@_];
		257	$coro->ready;
		258
		259	$coro
195	}	260	}
196		261
197	=item schedule	262	=item schedule
198		263
199	Calls the scheduler. Please note that the current process will not be put	264	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	265	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	266	never be called again unless something else (e.g. an event handler) calls
202	ready.	267	ready.
203		268
204	The canonical way to wait on external events is this:	269	The canonical way to wait on external events is this:
205		270
206	{	271	{
207	# remember current process	272	# remember current coroutine
208	my $current = $Coro::current;	273	my $current = $Coro::current;
209		274
210	# register a hypothetical event handler	275	# register a hypothetical event handler
211	on_event_invoke sub {	276	on_event_invoke sub {
212	# wake up sleeping coroutine	277	# wake up sleeping coroutine
213	$current->ready;	278	$current->ready;
214	undef $current;	279	undef $current;
215	};	280	};
216		281
217	# call schedule until event occured.	282	# call schedule until event occurred.
218	# in case we are woken up for other reasons	283	# in case we are woken up for other reasons
219	# (current still defined), loop.	284	# (current still defined), loop.
220	Coro::schedule while $current;	285	Coro::schedule while $current;
221	}	286	}
222		287
223	=cut
224
225	=item cede	288	=item cede
226		289
227	"Cede" to other processes. This function puts the current process into the	290	"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	291	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.	292	current "timeslice" to other coroutines of the same or higher priority.
230		293
231	=cut	294	Returns true if at least one coroutine switch has happened.
		295
		296	=item Coro::cede_notself
		297
		298	Works like cede, but is not exported by default and will cede to any
		299	coroutine, regardless of priority, once.
		300
		301	Returns true if at least one coroutine switch has happened.
232		302
233	=item terminate [arg...]	303	=item terminate [arg...]
234		304
235	Terminates the current process with the given status values (see L<cancel>).	305	Terminates the current coroutine with the given status values (see L<cancel>).
236		306
237	=cut	307	=cut
238		308
239	sub terminate {	309	sub terminate {
240	$current->cancel (@_);	310	$current->cancel (@_);
…		…
242		312
243	=back	313	=back
244		314
245	# dynamic methods	315	# dynamic methods
246		316
247	=head2 PROCESS METHODS	317	=head2 COROUTINE METHODS
248		318
249	These are the methods you can call on process objects.	319	These are the methods you can call on coroutine objects.
250		320
251	=over 4	321	=over 4
252		322
253	=item new Coro \&sub [, @args...]	323	=item new Coro \&sub [, @args...]
254		324
255	Create a new process and return it. When the sub returns the process	325	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	326	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	327	called. To make the coroutine run you must first put it into the ready queue
258	by calling the ready method.	328	by calling the ready method.
259		329
260	Calling C<exit> in a coroutine will not work correctly, so do not do that.	330	See C<async> for additional discussion.
261		331
262	=cut	332	=cut
263		333
264	sub _new_coro {	334	sub _run_coro {
265	terminate &{+shift};	335	terminate &{+shift};
266	}	336	}
267		337
268	sub new {	338	sub new {
269	my $class = shift;	339	my $class = shift;
270		340
271	$class->SUPER::new (\&_new_coro, @_)	341	$class->SUPER::new (\&_run_coro, @_)
272	}	342	}
273		343
274	=item $success = $process->ready	344	=item $success = $coroutine->ready
275		345
276	Put the given process into the ready queue (according to it's priority)	346	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	347	and return true. If the coroutine is already in the ready queue, do nothing
278	and return false.	348	and return false.
279		349
280	=item $is_ready = $process->is_ready	350	=item $is_ready = $coroutine->is_ready
281		351
282	Return wether the process is currently the ready queue or not,	352	Return wether the coroutine is currently the ready queue or not,
283		353
284	=item $process->cancel (arg...)	354	=item $coroutine->cancel (arg...)
285		355
286	Terminates the given process and makes it return the given arguments as	356	Terminates the given coroutine and makes it return the given arguments as
287	status (default: the empty list).	357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
288		359
289	=cut	360	=cut
290		361
291	sub cancel {	362	sub cancel {
292	my $self = shift;	363	my $self = shift;
293	$self->{status} = [@_];	364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
294	push @destroy, $self;	367	push @destroy, $self;
295	$manager->ready;	368	$manager->ready;
296	&schedule if $current == $self;	369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
297	}	373	}
298		374
299	=item $process->join	375	=item $coroutine->join
300		376
301	Wait until the coroutine terminates and return any values given to the	377	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	378	C<terminate> or C<cancel> functions. C<join> can be called multiple times
303	from multiple processes.	379	from multiple coroutine.
304		380
305	=cut	381	=cut
306		382
307	sub join {	383	sub join {
308	my $self = shift;	384	my $self = shift;
		385
309	unless ($self->{status}) {	386	unless ($self->{status}) {
310	push @{$self->{join}}, $current;	387	my $current = $current;
311	&schedule;	388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
312	}	395	}
		396
313	wantarray ? @{$self->{status}} : $self->{status}[0];	397	wantarray ? @{$self->{status}} : $self->{status}[0];
314	}	398	}
315		399
		400	=item $coroutine->on_destroy (\&cb)
		401
		402	Registers a callback that is called when this coroutine gets destroyed,
		403	but before it is joined. The callback gets passed the terminate arguments,
		404	if any.
		405
		406	=cut
		407
		408	sub on_destroy {
		409	my ($self, $cb) = @_;
		410
		411	push @{ $self->{destroy_cb} }, $cb;
		412	}
		413
316	=item $oldprio = $process->prio ($newprio)	414	=item $oldprio = $coroutine->prio ($newprio)
317		415
318	Sets (or gets, if the argument is missing) the priority of the	416	Sets (or gets, if the argument is missing) the priority of the
319	process. Higher priority processes get run before lower priority	417	coroutine. Higher priority coroutines get run before lower priority
320	processes. Priorities are small signed integers (currently -4 .. +3),	418	coroutines. Priorities are small signed integers (currently -4 .. +3),
321	that you can refer to using PRIO_xxx constants (use the import tag :prio	419	that you can refer to using PRIO_xxx constants (use the import tag :prio
322	to get then):	420	to get then):
323		421
324	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	422	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
325	3 > 1 > 0 > -1 > -3 > -4	423	3 > 1 > 0 > -1 > -3 > -4
…		…
328	current->prio(PRIO_HIGH);	426	current->prio(PRIO_HIGH);
329		427
330	The idle coroutine ($Coro::idle) always has a lower priority than any	428	The idle coroutine ($Coro::idle) always has a lower priority than any
331	existing coroutine.	429	existing coroutine.
332		430
333	Changing the priority of the current process will take effect immediately,	431	Changing the priority of the current coroutine will take effect immediately,
334	but changing the priority of processes in the ready queue (but not	432	but changing the priority of coroutines in the ready queue (but not
335	running) will only take effect after the next schedule (of that	433	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.	434	coroutine). This is a bug that will be fixed in some future version.
337		435
338	=item $newprio = $process->nice ($change)	436	=item $newprio = $coroutine->nice ($change)
339		437
340	Similar to C<prio>, but subtract the given value from the priority (i.e.	438	Similar to C<prio>, but subtract the given value from the priority (i.e.
341	higher values mean lower priority, just as in unix).	439	higher values mean lower priority, just as in unix).
342		440
343	=item $olddesc = $process->desc ($newdesc)	441	=item $olddesc = $coroutine->desc ($newdesc)
344		442
345	Sets (or gets in case the argument is missing) the description for this	443	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.	444	coroutine. This is just a free-form string you can associate with a coroutine.
347		445
348	=cut	446	=cut
349		447
350	sub desc {	448	sub desc {
351	my $old = $_[0]{desc};	449	my $old = $_[0]{desc};
…		…
353	$old;	451	$old;
354	}	452	}
355		453
356	=back	454	=back
357		455
		456	=head2 GLOBAL FUNCTIONS
		457
		458	=over 4
		459
		460	=item Coro::nready
		461
		462	Returns the number of coroutines that are currently in the ready state,
		463	i.e. that can be switched to. The value C<0> means that the only runnable
		464	coroutine is the currently running one, so C<cede> would have no effect,
		465	and C<schedule> would cause a deadlock unless there is an idle handler
		466	that wakes up some coroutines.
		467
		468	=item my $guard = Coro::guard { ... }
		469
		470	This creates and returns a guard object. Nothing happens until the object
		471	gets destroyed, in which case the codeblock given as argument will be
		472	executed. This is useful to free locks or other resources in case of a
		473	runtime error or when the coroutine gets canceled, as in both cases the
		474	guard block will be executed. The guard object supports only one method,
		475	C<< ->cancel >>, which will keep the codeblock from being executed.
		476
		477	Example: set some flag and clear it again when the coroutine gets canceled
		478	or the function returns:
		479
		480	sub do_something {
		481	my $guard = Coro::guard { $busy = 0 };
		482	$busy = 1;
		483
		484	# do something that requires $busy to be true
		485	}
		486
		487	=cut
		488
		489	sub guard(&) {
		490	bless \(my $cb = $_[0]), "Coro::guard"
		491	}
		492
		493	sub Coro::guard::cancel {
		494	${$_[0]} = sub { };
		495	}
		496
		497	sub Coro::guard::DESTROY {
		498	${$_[0]}->();
		499	}
		500
		501
		502	=item unblock_sub { ... }
		503
		504	This utility function takes a BLOCK or code reference and "unblocks" it,
		505	returning the new coderef. This means that the new coderef will return
		506	immediately without blocking, returning nothing, while the original code
		507	ref will be called (with parameters) from within its own coroutine.
		508
		509	The reason this function exists is that many event libraries (such as the
		510	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		511	of thread-safety). This means you must not block within event callbacks,
		512	otherwise you might suffer from crashes or worse.
		513
		514	This function allows your callbacks to block by executing them in another
		515	coroutine where it is safe to block. One example where blocking is handy
		516	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		517	disk.
		518
		519	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		520	creating event callbacks that want to block.
		521
		522	=cut
		523
		524	our @unblock_queue;
		525
		526	# we create a special coro because we want to cede,
		527	# to reduce pressure on the coro pool (because most callbacks
		528	# return immediately and can be reused) and because we cannot cede
		529	# inside an event callback.
		530	our $unblock_scheduler = async {
		531	while () {
		532	while (my $cb = pop @unblock_queue) {
		533	# this is an inlined copy of async_pool
		534	my $coro = (pop @pool or new Coro \&pool_handler);
		535
		536	$coro->{_invoke} = $cb;
		537	$coro->ready;
		538	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		539	}
		540	schedule; # sleep well
		541	}
		542	};
		543
		544	sub unblock_sub(&) {
		545	my $cb = shift;
		546
		547	sub {
		548	unshift @unblock_queue, [$cb, @_];
		549	$unblock_scheduler->ready;
		550	}
		551	}
		552
		553	=back
		554
358	=cut	555	=cut
359		556
360	1;	557	1;
361		558
362	=head1 BUGS/LIMITATIONS	559	=head1 BUGS/LIMITATIONS
363		560
364	- you must make very sure that no coro is still active on global	561	- you must make very sure that no coro is still active on global
365	destruction. very bad things might happen otherwise (usually segfaults).	562	destruction. very bad things might happen otherwise (usually segfaults).
366		563
367	- this module is not thread-safe. You should only ever use this module	564	- this module is not thread-safe. You should only ever use this module
368	from the same thread (this requirement might be losened in the future	565	from the same thread (this requirement might be loosened in the future
369	to allow per-thread schedulers, but Coro::State does not yet allow	566	to allow per-thread schedulers, but Coro::State does not yet allow
370	this).	567	this).
371		568
372	=head1 SEE ALSO	569	=head1 SEE ALSO
373		570

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 1.125 by root, Fri Apr 27 19:35:58 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 1.125 by root, Fri Apr 27 19:35:58 2007 UTC