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

Comparing Coro/Coro.pm (file contents):
Revision 1.80 by root, Mon Nov 6 19:56:26 2006 UTC vs.
Revision 1.106 by root, Fri Jan 5 17:44:17 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 = '2.5';	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.
167		191
168	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
169	program.	193	program.
170		194
171	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
…		…
174	} 1,2,3,4;	198	} 1,2,3,4;
175		199
176	=cut	200	=cut
177		201
178	sub async(&@) {	202	sub async(&@) {
179	my $pid = new Coro @_;	203	my $coro = new Coro @_;
180	$manager->ready; # this ensures that the stack is cloned from the manager
181	$pid->ready;	204	$coro->ready;
182	$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 C<async> does.
		216
		217	The priority will be reset to C<0> after each job, otherwise the coroutine
		218	will be re-used "as-is".
		219
		220	The pool size is limited to 8 idle coroutines (this can be adjusted by
		221	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		222	required.
		223
		224	If you are concerned about pooled coroutines growing a lot because a
		225	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		226	terminate }> once per second or so to slowly replenish the pool.
		227
		228	=cut
		229
		230	our $POOL_SIZE = 8;
		231	our @pool;
		232
		233	sub pool_handler {
		234	while () {
		235	my ($cb, @arg) = @{ delete $current->{_invoke} };
		236
		237	eval {
		238	$cb->(@arg);
		239	};
		240	warn $@ if $@;
		241
		242	last if @pool >= $POOL_SIZE;
		243	push @pool, $current;
		244
		245	$current->prio (0);
		246	schedule;
		247	}
		248	}
		249
		250	sub async_pool(&@) {
		251	# this is also inlined into the unlock_scheduler
		252	my $coro = (pop @pool or new Coro \&pool_handler);
		253
		254	$coro->{_invoke} = [@_];
		255	$coro->ready;
		256
		257	$coro
183	}	258	}
184		259
185	=item schedule	260	=item schedule
186		261
187	Calls the scheduler. Please note that the current process will not be put	262	Calls the scheduler. Please note that the current coroutine will not be put
188	into the ready queue, so calling this function usually means you will	263	into the ready queue, so calling this function usually means you will
189	never be called again.	264	never be called again unless something else (e.g. an event handler) calls
		265	ready.
190		266
191	=cut	267	The canonical way to wait on external events is this:
		268
		269	{
		270	# remember current coroutine
		271	my $current = $Coro::current;
		272
		273	# register a hypothetical event handler
		274	on_event_invoke sub {
		275	# wake up sleeping coroutine
		276	$current->ready;
		277	undef $current;
		278	};
		279
		280	# call schedule until event occured.
		281	# in case we are woken up for other reasons
		282	# (current still defined), loop.
		283	Coro::schedule while $current;
		284	}
192		285
193	=item cede	286	=item cede
194		287
195	"Cede" to other processes. This function puts the current process into the	288	"Cede" to other coroutines. This function puts the current coroutine into the
196	ready queue and calls C<schedule>, which has the effect of giving up the	289	ready queue and calls C<schedule>, which has the effect of giving up the
197	current "timeslice" to other coroutines of the same or higher priority.	290	current "timeslice" to other coroutines of the same or higher priority.
198		291
199	=cut	292	=item Coro::cede_notself
		293
		294	Works like cede, but is not exported by default and will cede to any
		295	coroutine, regardless of priority, once.
200		296
201	=item terminate [arg...]	297	=item terminate [arg...]
202		298
203	Terminates the current process with the given status values (see L<cancel>).	299	Terminates the current coroutine with the given status values (see L<cancel>).
204		300
205	=cut	301	=cut
206		302
207	sub terminate {	303	sub terminate {
208	$current->cancel (@_);	304	$current->cancel (@_);
…		…
210		306
211	=back	307	=back
212		308
213	# dynamic methods	309	# dynamic methods
214		310
215	=head2 PROCESS METHODS	311	=head2 COROUTINE METHODS
216		312
217	These are the methods you can call on process objects.	313	These are the methods you can call on coroutine objects.
218		314
219	=over 4	315	=over 4
220		316
221	=item new Coro \&sub [, @args...]	317	=item new Coro \&sub [, @args...]
222		318
223	Create a new process and return it. When the sub returns the process	319	Create a new coroutine and return it. When the sub returns the coroutine
224	automatically terminates as if C<terminate> with the returned values were	320	automatically terminates as if C<terminate> with the returned values were
225	called. To make the process run you must first put it into the ready queue	321	called. To make the coroutine run you must first put it into the ready queue
226	by calling the ready method.	322	by calling the ready method.
227		323
228	=cut	324	Calling C<exit> in a coroutine will not work correctly, so do not do that.
229		325
		326	=cut
		327
230	sub _newcoro {	328	sub _run_coro {
231	terminate &{+shift};	329	terminate &{+shift};
232	}	330	}
233		331
234	sub new {	332	sub new {
235	my $class = shift;	333	my $class = shift;
236	bless {
237	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
238	}, $class;
239	}
240		334
241	=item $process->ready	335	$class->SUPER::new (\&_run_coro, @_)
		336	}
242		337
243	Put the given process into the ready queue.	338	=item $success = $coroutine->ready
244		339
245	=cut	340	Put the given coroutine into the ready queue (according to it's priority)
		341	and return true. If the coroutine is already in the ready queue, do nothing
		342	and return false.
246		343
		344	=item $is_ready = $coroutine->is_ready
		345
		346	Return wether the coroutine is currently the ready queue or not,
		347
247	=item $process->cancel (arg...)	348	=item $coroutine->cancel (arg...)
248		349
249	Terminates the given process and makes it return the given arguments as	350	Terminates the given coroutine and makes it return the given arguments as
250	status (default: the empty list).	351	status (default: the empty list). Never returns if the coroutine is the
		352	current coroutine.
251		353
252	=cut	354	=cut
253		355
254	sub cancel {	356	sub cancel {
255	my $self = shift;	357	my $self = shift;
256	$self->{status} = [@_];	358	$self->{status} = [@_];
		359
		360	if ($current == $self) {
257	push @destroy, $self;	361	push @destroy, $self;
258	$manager->ready;	362	$manager->ready;
259	&schedule if $current == $self;	363	&schedule while 1;
		364	} else {
		365	$self->_cancel;
		366	}
260	}	367	}
261		368
262	=item $process->join	369	=item $coroutine->join
263		370
264	Wait until the coroutine terminates and return any values given to the	371	Wait until the coroutine terminates and return any values given to the
265	C<terminate> or C<cancel> functions. C<join> can be called multiple times	372	C<terminate> or C<cancel> functions. C<join> can be called multiple times
266	from multiple processes.	373	from multiple coroutine.
267		374
268	=cut	375	=cut
269		376
270	sub join {	377	sub join {
271	my $self = shift;	378	my $self = shift;
		379
272	unless ($self->{status}) {	380	unless ($self->{status}) {
273	push @{$self->{join}}, $current;	381	my $current = $current;
274	&schedule;	382
		383	push @{$self->{destroy_cb}}, sub {
		384	$current->ready;
		385	undef $current;
		386	};
		387
		388	&schedule while $current;
275	}	389	}
		390
276	wantarray ? @{$self->{status}} : $self->{status}[0];	391	wantarray ? @{$self->{status}} : $self->{status}[0];
277	}	392	}
278		393
		394	=item $coroutine->on_destroy (\&cb)
		395
		396	Registers a callback that is called when this coroutine gets destroyed,
		397	but before it is joined. The callback gets passed the terminate arguments,
		398	if any.
		399
		400	=cut
		401
		402	sub on_destroy {
		403	my ($self, $cb) = @_;
		404
		405	push @{ $self->{destroy_cb} }, $cb;
		406	}
		407
279	=item $oldprio = $process->prio($newprio)	408	=item $oldprio = $coroutine->prio ($newprio)
280		409
281	Sets (or gets, if the argument is missing) the priority of the	410	Sets (or gets, if the argument is missing) the priority of the
282	process. Higher priority processes get run before lower priority	411	coroutine. Higher priority coroutines get run before lower priority
283	processes. Priorities are small signed integers (currently -4 .. +3),	412	coroutines. Priorities are small signed integers (currently -4 .. +3),
284	that you can refer to using PRIO_xxx constants (use the import tag :prio	413	that you can refer to using PRIO_xxx constants (use the import tag :prio
285	to get then):	414	to get then):
286		415
287	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	416	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
288	3 > 1 > 0 > -1 > -3 > -4	417	3 > 1 > 0 > -1 > -3 > -4
…		…
291	current->prio(PRIO_HIGH);	420	current->prio(PRIO_HIGH);
292		421
293	The idle coroutine ($Coro::idle) always has a lower priority than any	422	The idle coroutine ($Coro::idle) always has a lower priority than any
294	existing coroutine.	423	existing coroutine.
295		424
296	Changing the priority of the current process will take effect immediately,	425	Changing the priority of the current coroutine will take effect immediately,
297	but changing the priority of processes in the ready queue (but not	426	but changing the priority of coroutines in the ready queue (but not
298	running) will only take effect after the next schedule (of that	427	running) will only take effect after the next schedule (of that
299	process). This is a bug that will be fixed in some future version.	428	coroutine). This is a bug that will be fixed in some future version.
300		429
301	=cut
302
303	sub prio {
304	my $old = $_[0]{prio};
305	$_[0]{prio} = $_[1] if @_ > 1;
306	$old;
307	}
308
309	=item $newprio = $process->nice($change)	430	=item $newprio = $coroutine->nice ($change)
310		431
311	Similar to C<prio>, but subtract the given value from the priority (i.e.	432	Similar to C<prio>, but subtract the given value from the priority (i.e.
312	higher values mean lower priority, just as in unix).	433	higher values mean lower priority, just as in unix).
313		434
314	=cut
315
316	sub nice {
317	$_[0]{prio} -= $_[1];
318	}
319
320	=item $olddesc = $process->desc($newdesc)	435	=item $olddesc = $coroutine->desc ($newdesc)
321		436
322	Sets (or gets in case the argument is missing) the description for this	437	Sets (or gets in case the argument is missing) the description for this
323	process. This is just a free-form string you can associate with a process.	438	coroutine. This is just a free-form string you can associate with a coroutine.
324		439
325	=cut	440	=cut
326		441
327	sub desc {	442	sub desc {
328	my $old = $_[0]{desc};	443	my $old = $_[0]{desc};
…		…
330	$old;	445	$old;
331	}	446	}
332		447
333	=back	448	=back
334		449
		450	=head2 GLOBAL FUNCTIONS
		451
		452	=over 4
		453
		454	=item Coro::nready
		455
		456	Returns the number of coroutines that are currently in the ready state,
		457	i.e. that can be swicthed to. The value C<0> means that the only runnable
		458	coroutine is the currently running one, so C<cede> would have no effect,
		459	and C<schedule> would cause a deadlock unless there is an idle handler
		460	that wakes up some coroutines.
		461
		462	=item my $guard = Coro::guard { ... }
		463
		464	This creates and returns a guard object. Nothing happens until the objetc
		465	gets destroyed, in which case the codeblock given as argument will be
		466	executed. This is useful to free locks or other resources in case of a
		467	runtime error or when the coroutine gets canceled, as in both cases the
		468	guard block will be executed. The guard object supports only one method,
		469	C<< ->cancel >>, which will keep the codeblock from being executed.
		470
		471	Example: set some flag and clear it again when the coroutine gets canceled
		472	or the function returns:
		473
		474	sub do_something {
		475	my $guard = Coro::guard { $busy = 0 };
		476	$busy = 1;
		477
		478	# do something that requires $busy to be true
		479	}
		480
		481	=cut
		482
		483	sub guard(&) {
		484	bless \(my $cb = $_[0]), "Coro::guard"
		485	}
		486
		487	sub Coro::guard::cancel {
		488	${$_[0]} = sub { };
		489	}
		490
		491	sub Coro::guard::DESTROY {
		492	${$_[0]}->();
		493	}
		494
		495
		496	=item unblock_sub { ... }
		497
		498	This utility function takes a BLOCK or code reference and "unblocks" it,
		499	returning the new coderef. This means that the new coderef will return
		500	immediately without blocking, returning nothing, while the original code
		501	ref will be called (with parameters) from within its own coroutine.
		502
		503	The reason this fucntion exists is that many event libraries (such as the
		504	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		505	of thread-safety). This means you must not block within event callbacks,
		506	otherwise you might suffer from crashes or worse.
		507
		508	This function allows your callbacks to block by executing them in another
		509	coroutine where it is safe to block. One example where blocking is handy
		510	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		511	disk.
		512
		513	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		514	creating event callbacks that want to block.
		515
		516	=cut
		517
		518	our @unblock_queue;
		519
		520	# we create a special coro because we want to cede,
		521	# to reduce pressure on the coro pool (because most callbacks
		522	# return immediately and can be reused) and because we cannot cede
		523	# inside an event callback.
		524	our $unblock_scheduler = async {
		525	while () {
		526	while (my $cb = pop @unblock_queue) {
		527	# this is an inlined copy of async_pool
		528	my $coro = (pop @pool or new Coro \&pool_handler);
		529
		530	$coro->{_invoke} = $cb;
		531	$coro->ready;
		532	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		533	}
		534	schedule; # sleep well
		535	}
		536	};
		537
		538	sub unblock_sub(&) {
		539	my $cb = shift;
		540
		541	sub {
		542	unshift @unblock_queue, [$cb, @_];
		543	$unblock_scheduler->ready;
		544	}
		545	}
		546
		547	=back
		548
335	=cut	549	=cut
336		550
337	1;	551	1;
338		552
339	=head1 BUGS/LIMITATIONS	553	=head1 BUGS/LIMITATIONS

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Comparing Coro/Coro.pm (file contents): Revision 1.80 by root, Mon Nov 6 19:56:26 2006 UTC vs. Revision 1.106 by root, Fri Jan 5 17:44:17 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.80 by root, Mon Nov 6 19:56:26 2006 UTC vs.
Revision 1.106 by root, Fri Jan 5 17:44:17 2007 UTC