[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 1.115 by root, Wed Feb 28 11:43:03 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 $VERSION = '3.501';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
		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 $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	eval {
		239	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		240	$cb->(@arg);
		241	};
		242	warn $@ if $@;
		243
		244	last if @pool >= $POOL_SIZE;
		245	push @pool, $current;
		246
		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
183	}	260	}
184		261
185	=item schedule	262	=item schedule
186		263
187	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
188	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
189	never be called again.	266	never be called again unless something else (e.g. an event handler) calls
		267	ready.
190		268
191	=cut	269	The canonical way to wait on external events is this:
		270
		271	{
		272	# remember current coroutine
		273	my $current = $Coro::current;
		274
		275	# register a hypothetical event handler
		276	on_event_invoke sub {
		277	# wake up sleeping coroutine
		278	$current->ready;
		279	undef $current;
		280	};
		281
		282	# call schedule until event occured.
		283	# in case we are woken up for other reasons
		284	# (current still defined), loop.
		285	Coro::schedule while $current;
		286	}
192		287
193	=item cede	288	=item cede
194		289
195	"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
196	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
197	current "timeslice" to other coroutines of the same or higher priority.	292	current "timeslice" to other coroutines of the same or higher priority.
198		293
199	=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.
200		302
201	=item terminate [arg...]	303	=item terminate [arg...]
202		304
203	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>).
204		306
205	=cut	307	=cut
206		308
207	sub terminate {	309	sub terminate {
208	$current->cancel (@_);	310	$current->cancel (@_);
…		…
210		312
211	=back	313	=back
212		314
213	# dynamic methods	315	# dynamic methods
214		316
215	=head2 PROCESS METHODS	317	=head2 COROUTINE METHODS
216		318
217	These are the methods you can call on process objects.	319	These are the methods you can call on coroutine objects.
218		320
219	=over 4	321	=over 4
220		322
221	=item new Coro \&sub [, @args...]	323	=item new Coro \&sub [, @args...]
222		324
223	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
224	automatically terminates as if C<terminate> with the returned values were	326	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	327	called. To make the coroutine run you must first put it into the ready queue
226	by calling the ready method.	328	by calling the ready method.
227		329
228	=cut	330	Calling C<exit> in a coroutine will not work correctly, so do not do that.
229		331
		332	=cut
		333
230	sub _newcoro {	334	sub _run_coro {
231	terminate &{+shift};	335	terminate &{+shift};
232	}	336	}
233		337
234	sub new {	338	sub new {
235	my $class = shift;	339	my $class = shift;
236	bless {
237	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
238	}, $class;
239	}
240		340
241	=item $process->ready	341	$class->SUPER::new (\&_run_coro, @_)
		342	}
242		343
243	Put the given process into the ready queue.	344	=item $success = $coroutine->ready
244		345
245	=cut	346	Put the given coroutine into the ready queue (according to it's priority)
		347	and return true. If the coroutine is already in the ready queue, do nothing
		348	and return false.
246		349
		350	=item $is_ready = $coroutine->is_ready
		351
		352	Return wether the coroutine is currently the ready queue or not,
		353
247	=item $process->cancel (arg...)	354	=item $coroutine->cancel (arg...)
248		355
249	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
250	status (default: the empty list).	357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
251		359
252	=cut	360	=cut
253		361
254	sub cancel {	362	sub cancel {
255	my $self = shift;	363	my $self = shift;
256	$self->{status} = [@_];	364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
257	push @destroy, $self;	367	push @destroy, $self;
258	$manager->ready;	368	$manager->ready;
259	&schedule if $current == $self;	369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
260	}	373	}
261		374
262	=item $process->join	375	=item $coroutine->join
263		376
264	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
265	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
266	from multiple processes.	379	from multiple coroutine.
267		380
268	=cut	381	=cut
269		382
270	sub join {	383	sub join {
271	my $self = shift;	384	my $self = shift;
		385
272	unless ($self->{status}) {	386	unless ($self->{status}) {
273	push @{$self->{join}}, $current;	387	my $current = $current;
274	&schedule;	388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
275	}	395	}
		396
276	wantarray ? @{$self->{status}} : $self->{status}[0];	397	wantarray ? @{$self->{status}} : $self->{status}[0];
277	}	398	}
278		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
279	=item $oldprio = $process->prio($newprio)	414	=item $oldprio = $coroutine->prio ($newprio)
280		415
281	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
282	process. Higher priority processes get run before lower priority	417	coroutine. Higher priority coroutines get run before lower priority
283	processes. Priorities are small signed integers (currently -4 .. +3),	418	coroutines. Priorities are small signed integers (currently -4 .. +3),
284	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
285	to get then):	420	to get then):
286		421
287	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
288	3 > 1 > 0 > -1 > -3 > -4	423	3 > 1 > 0 > -1 > -3 > -4
…		…
291	current->prio(PRIO_HIGH);	426	current->prio(PRIO_HIGH);
292		427
293	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
294	existing coroutine.	429	existing coroutine.
295		430
296	Changing the priority of the current process will take effect immediately,	431	Changing the priority of the current coroutine will take effect immediately,
297	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
298	running) will only take effect after the next schedule (of that	433	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.	434	coroutine). This is a bug that will be fixed in some future version.
300		435
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)	436	=item $newprio = $coroutine->nice ($change)
310		437
311	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.
312	higher values mean lower priority, just as in unix).	439	higher values mean lower priority, just as in unix).
313		440
314	=cut
315
316	sub nice {
317	$_[0]{prio} -= $_[1];
318	}
319
320	=item $olddesc = $process->desc($newdesc)	441	=item $olddesc = $coroutine->desc ($newdesc)
321		442
322	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
323	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.
324		445
325	=cut	446	=cut
326		447
327	sub desc {	448	sub desc {
328	my $old = $_[0]{desc};	449	my $old = $_[0]{desc};
…		…
330	$old;	451	$old;
331	}	452	}
332		453
333	=back	454	=back
334		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 swicthed 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 objetc
		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 fucntion 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
335	=cut	555	=cut
336		556
337	1;	557	1;
338		558
339	=head1 BUGS/LIMITATIONS	559	=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 1.115 by root, Wed Feb 28 11:43:03 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 1.115 by root, Wed Feb 28 11:43:03 2007 UTC