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

Comparing Coro/Coro.pm (file contents):
Revision 1.83 by root, Fri Nov 24 15:34:33 2006 UTC vs.
Revision 1.132 by root, Thu Sep 20 22:53:23 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 = '2.5';	55	our $VERSION = '3.7';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
		118	$main->{desc} = "[main::]";
		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
112	}	122	if $current;
113		123
114	$current = $main;	124	_set_current $main;
115		125
116	sub current() { $current }	126	sub current() { $current }
117		127
118	=item $idle	128	=item $idle
119		129
120	A callback that is called whenever the scheduler finds no ready coroutines	130	A callback that is called whenever the scheduler finds no ready coroutines
121	to run. The default implementation prints "FATAL: deadlock detected" and	131	to run. The default implementation prints "FATAL: deadlock detected" and
122	exits.	132	exits, because the program has no other way to continue.
123		133
124	This hook is overwritten by modules such as C<Coro::Timer> and	134	This hook is overwritten by modules such as C<Coro::Timer> and
125	C<Coro::Event> to wait on an external event that hopefully wakes up some	135	C<Coro::Event> to wait on an external event that hopefully wake up a
126	coroutine.	136	coroutine so the scheduler can run it.
		137
		138	Please note that if your callback recursively invokes perl (e.g. for event
		139	handlers), then it must be prepared to be called recursively.
127		140
128	=cut	141	=cut
129		142
130	$idle = sub {	143	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
132	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
133	};	146	};
		147
		148	sub _cancel {
		149	my ($self) = @_;
		150
		151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
		154
		155	# call all destruction callbacks
		156	$_->(@{$self->{status}})
		157	for @{(delete $self->{destroy_cb}) \|\| []};
		158	}
134		159
135	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	161	# cannot destroy itself.
137	my @destroy;	162	my @destroy;
138	my $manager;	163	my $manager;
		164
139	$manager = new Coro sub {	165	$manager = new Coro sub {
140	while () {	166	while () {
141	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
142	# while still being able to schedule this coroutine (in case it has
143	# been readied multiple times. this is harmless since the manager
144	# can be called as many times as neccessary and will always
145	# remove itself from the runqueue
146	while (@destroy) {	168	while @destroy;
147	my $coro = pop @destroy;
148	$coro->{status} \|\|= [];
149	$_->ready for @{delete $coro->{join} \|\| []};
150		169
151	# the next line destroys the coro state, but keeps the
152	# process itself intact (we basically make it a zombie
153	# process that always runs the manager thread, so it's possible
154	# to transfer() to this process).
155	$coro->_clone_state_from ($manager);
156	}
157	&schedule;	170	&schedule;
158	}	171	}
159	};	172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
160		175
161	# static methods. not really.	176	# static methods. not really.
162		177
163	=back	178	=back
164		179
165	=head2 STATIC METHODS	180	=head2 STATIC METHODS
166		181
167	Static methods are actually functions that operate on the current process only.	182	Static methods are actually functions that operate on the current coroutine only.
168		183
169	=over 4	184	=over 4
170		185
171	=item async { ... } [@args...]	186	=item async { ... } [@args...]
172		187
173	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
174	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
175	terminated.	190	terminated.
176		191
177	When the coroutine dies, the program will exit, just as in the main	192	Calling C<exit> in a coroutine will do the same as calling exit outside
178	program.	193	the coroutine. Likewise, when the coroutine dies, the program will exit,
		194	just as it would in the main program.
179		195
180	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
181	async {	197	async {
182	print "@_\n";	198	print "@_\n";
183	} 1,2,3,4;	199	} 1,2,3,4;
184		200
185	=cut	201	=cut
186		202
187	sub async(&@) {	203	sub async(&@) {
188	my $pid = new Coro @_;	204	my $coro = new Coro @_;
189	$manager->ready; # this ensures that the stack is cloned from the manager
190	$pid->ready;	205	$coro->ready;
191	$pid;	206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		230	terminate }> once per second or so to slowly replenish the pool.
		231
		232	=cut
		233
		234	our $POOL_SIZE = 8;
		235	our $MAX_POOL_RSS = 64 * 1024;
		236	our @pool;
		237
		238	sub pool_handler {
		239	while () {
		240	$current->{desc} = "[async_pool]";
		241
		242	eval {
		243	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		244	$cb->(@arg);
		245	};
		246	warn $@ if $@;
		247
		248	last if @pool >= $POOL_SIZE \|\| $current->rss >= $MAX_POOL_RSS;
		249
		250	push @pool, $current;
		251	$current->{desc} = "[async_pool idle]";
		252	$current->save (Coro::State::SAVE_DEF);
		253	$current->prio (0);
		254	schedule;
		255	}
		256	}
		257
		258	sub async_pool(&@) {
		259	# this is also inlined into the unlock_scheduler
		260	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		261
		262	$coro->{_invoke} = [@_];
		263	$coro->ready;
		264
		265	$coro
192	}	266	}
193		267
194	=item schedule	268	=item schedule
195		269
196	Calls the scheduler. Please note that the current process will not be put	270	Calls the scheduler. Please note that the current coroutine will not be put
197	into the ready queue, so calling this function usually means you will	271	into the ready queue, so calling this function usually means you will
198	never be called again.	272	never be called again unless something else (e.g. an event handler) calls
		273	ready.
199		274
200	=cut	275	The canonical way to wait on external events is this:
		276
		277	{
		278	# remember current coroutine
		279	my $current = $Coro::current;
		280
		281	# register a hypothetical event handler
		282	on_event_invoke sub {
		283	# wake up sleeping coroutine
		284	$current->ready;
		285	undef $current;
		286	};
		287
		288	# call schedule until event occurred.
		289	# in case we are woken up for other reasons
		290	# (current still defined), loop.
		291	Coro::schedule while $current;
		292	}
201		293
202	=item cede	294	=item cede
203		295
204	"Cede" to other processes. This function puts the current process into the	296	"Cede" to other coroutines. This function puts the current coroutine into the
205	ready queue and calls C<schedule>, which has the effect of giving up the	297	ready queue and calls C<schedule>, which has the effect of giving up the
206	current "timeslice" to other coroutines of the same or higher priority.	298	current "timeslice" to other coroutines of the same or higher priority.
207		299
208	=cut	300	Returns true if at least one coroutine switch has happened.
		301
		302	=item Coro::cede_notself
		303
		304	Works like cede, but is not exported by default and will cede to any
		305	coroutine, regardless of priority, once.
		306
		307	Returns true if at least one coroutine switch has happened.
209		308
210	=item terminate [arg...]	309	=item terminate [arg...]
211		310
212	Terminates the current process with the given status values (see L<cancel>).	311	Terminates the current coroutine with the given status values (see L<cancel>).
213		312
214	=cut	313	=cut
215		314
216	sub terminate {	315	sub terminate {
217	$current->cancel (@_);	316	$current->cancel (@_);
…		…
219		318
220	=back	319	=back
221		320
222	# dynamic methods	321	# dynamic methods
223		322
224	=head2 PROCESS METHODS	323	=head2 COROUTINE METHODS
225		324
226	These are the methods you can call on process objects.	325	These are the methods you can call on coroutine objects.
227		326
228	=over 4	327	=over 4
229		328
230	=item new Coro \&sub [, @args...]	329	=item new Coro \&sub [, @args...]
231		330
232	Create a new process and return it. When the sub returns the process	331	Create a new coroutine and return it. When the sub returns the coroutine
233	automatically terminates as if C<terminate> with the returned values were	332	automatically terminates as if C<terminate> with the returned values were
234	called. To make the process run you must first put it into the ready queue	333	called. To make the coroutine run you must first put it into the ready queue
235	by calling the ready method.	334	by calling the ready method.
236		335
237	=cut	336	See C<async> for additional discussion.
238		337
		338	=cut
		339
239	sub _newcoro {	340	sub _run_coro {
240	terminate &{+shift};	341	terminate &{+shift};
241	}	342	}
242		343
243	sub new {	344	sub new {
244	my $class = shift;	345	my $class = shift;
245		346
246	$class->SUPER::new (\&_newcoro, @_)	347	$class->SUPER::new (\&_run_coro, @_)
247	}	348	}
248		349
249	=item $process->ready	350	=item $success = $coroutine->ready
250		351
251	Put the given process into the ready queue.	352	Put the given coroutine into the ready queue (according to it's priority)
		353	and return true. If the coroutine is already in the ready queue, do nothing
		354	and return false.
252		355
253	=cut	356	=item $is_ready = $coroutine->is_ready
254		357
		358	Return wether the coroutine is currently the ready queue or not,
		359
255	=item $process->cancel (arg...)	360	=item $coroutine->cancel (arg...)
256		361
257	Terminates the given process and makes it return the given arguments as	362	Terminates the given coroutine and makes it return the given arguments as
258	status (default: the empty list).	363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
259		365
260	=cut	366	=cut
261		367
262	sub cancel {	368	sub cancel {
263	my $self = shift;	369	my $self = shift;
264	$self->{status} = [@_];	370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
265	push @destroy, $self;	373	push @destroy, $self;
266	$manager->ready;	374	$manager->ready;
267	&schedule if $current == $self;	375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
268	}	379	}
269		380
270	=item $process->join	381	=item $coroutine->join
271		382
272	Wait until the coroutine terminates and return any values given to the	383	Wait until the coroutine terminates and return any values given to the
273	C<terminate> or C<cancel> functions. C<join> can be called multiple times	384	C<terminate> or C<cancel> functions. C<join> can be called multiple times
274	from multiple processes.	385	from multiple coroutine.
275		386
276	=cut	387	=cut
277		388
278	sub join {	389	sub join {
279	my $self = shift;	390	my $self = shift;
		391
280	unless ($self->{status}) {	392	unless ($self->{status}) {
281	push @{$self->{join}}, $current;	393	my $current = $current;
282	&schedule;	394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
283	}	401	}
		402
284	wantarray ? @{$self->{status}} : $self->{status}[0];	403	wantarray ? @{$self->{status}} : $self->{status}[0];
285	}	404	}
286		405
		406	=item $coroutine->on_destroy (\&cb)
		407
		408	Registers a callback that is called when this coroutine gets destroyed,
		409	but before it is joined. The callback gets passed the terminate arguments,
		410	if any.
		411
		412	=cut
		413
		414	sub on_destroy {
		415	my ($self, $cb) = @_;
		416
		417	push @{ $self->{destroy_cb} }, $cb;
		418	}
		419
287	=item $oldprio = $process->prio ($newprio)	420	=item $oldprio = $coroutine->prio ($newprio)
288		421
289	Sets (or gets, if the argument is missing) the priority of the	422	Sets (or gets, if the argument is missing) the priority of the
290	process. Higher priority processes get run before lower priority	423	coroutine. Higher priority coroutines get run before lower priority
291	processes. Priorities are small signed integers (currently -4 .. +3),	424	coroutines. Priorities are small signed integers (currently -4 .. +3),
292	that you can refer to using PRIO_xxx constants (use the import tag :prio	425	that you can refer to using PRIO_xxx constants (use the import tag :prio
293	to get then):	426	to get then):
294		427
295	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	428	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
296	3 > 1 > 0 > -1 > -3 > -4	429	3 > 1 > 0 > -1 > -3 > -4
…		…
299	current->prio(PRIO_HIGH);	432	current->prio(PRIO_HIGH);
300		433
301	The idle coroutine ($Coro::idle) always has a lower priority than any	434	The idle coroutine ($Coro::idle) always has a lower priority than any
302	existing coroutine.	435	existing coroutine.
303		436
304	Changing the priority of the current process will take effect immediately,	437	Changing the priority of the current coroutine will take effect immediately,
305	but changing the priority of processes in the ready queue (but not	438	but changing the priority of coroutines in the ready queue (but not
306	running) will only take effect after the next schedule (of that	439	running) will only take effect after the next schedule (of that
307	process). This is a bug that will be fixed in some future version.	440	coroutine). This is a bug that will be fixed in some future version.
308		441
309	=item $newprio = $process->nice ($change)	442	=item $newprio = $coroutine->nice ($change)
310		443
311	Similar to C<prio>, but subtract the given value from the priority (i.e.	444	Similar to C<prio>, but subtract the given value from the priority (i.e.
312	higher values mean lower priority, just as in unix).	445	higher values mean lower priority, just as in unix).
313		446
314	=item $olddesc = $process->desc ($newdesc)	447	=item $olddesc = $coroutine->desc ($newdesc)
315		448
316	Sets (or gets in case the argument is missing) the description for this	449	Sets (or gets in case the argument is missing) the description for this
317	process. This is just a free-form string you can associate with a process.	450	coroutine. This is just a free-form string you can associate with a coroutine.
318		451
319	=cut	452	=cut
320		453
321	sub desc {	454	sub desc {
322	my $old = $_[0]{desc};	455	my $old = $_[0]{desc};
…		…
324	$old;	457	$old;
325	}	458	}
326		459
327	=back	460	=back
328		461
		462	=head2 GLOBAL FUNCTIONS
		463
		464	=over 4
		465
		466	=item Coro::nready
		467
		468	Returns the number of coroutines that are currently in the ready state,
		469	i.e. that can be switched to. The value C<0> means that the only runnable
		470	coroutine is the currently running one, so C<cede> would have no effect,
		471	and C<schedule> would cause a deadlock unless there is an idle handler
		472	that wakes up some coroutines.
		473
		474	=item my $guard = Coro::guard { ... }
		475
		476	This creates and returns a guard object. Nothing happens until the object
		477	gets destroyed, in which case the codeblock given as argument will be
		478	executed. This is useful to free locks or other resources in case of a
		479	runtime error or when the coroutine gets canceled, as in both cases the
		480	guard block will be executed. The guard object supports only one method,
		481	C<< ->cancel >>, which will keep the codeblock from being executed.
		482
		483	Example: set some flag and clear it again when the coroutine gets canceled
		484	or the function returns:
		485
		486	sub do_something {
		487	my $guard = Coro::guard { $busy = 0 };
		488	$busy = 1;
		489
		490	# do something that requires $busy to be true
		491	}
		492
		493	=cut
		494
		495	sub guard(&) {
		496	bless \(my $cb = $_[0]), "Coro::guard"
		497	}
		498
		499	sub Coro::guard::cancel {
		500	${$_[0]} = sub { };
		501	}
		502
		503	sub Coro::guard::DESTROY {
		504	${$_[0]}->();
		505	}
		506
		507
		508	=item unblock_sub { ... }
		509
		510	This utility function takes a BLOCK or code reference and "unblocks" it,
		511	returning the new coderef. This means that the new coderef will return
		512	immediately without blocking, returning nothing, while the original code
		513	ref will be called (with parameters) from within its own coroutine.
		514
		515	The reason this function exists is that many event libraries (such as the
		516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		517	of thread-safety). This means you must not block within event callbacks,
		518	otherwise you might suffer from crashes or worse.
		519
		520	This function allows your callbacks to block by executing them in another
		521	coroutine where it is safe to block. One example where blocking is handy
		522	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		523	disk.
		524
		525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		526	creating event callbacks that want to block.
		527
		528	=cut
		529
		530	our @unblock_queue;
		531
		532	# we create a special coro because we want to cede,
		533	# to reduce pressure on the coro pool (because most callbacks
		534	# return immediately and can be reused) and because we cannot cede
		535	# inside an event callback.
		536	our $unblock_scheduler = new Coro sub {
		537	while () {
		538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
		540	my $coro = (pop @pool or new Coro \&pool_handler);
		541
		542	$coro->{_invoke} = $cb;
		543	$coro->ready;
		544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		545	}
		546	schedule; # sleep well
		547	}
		548	};
		549	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		550
		551	sub unblock_sub(&) {
		552	my $cb = shift;
		553
		554	sub {
		555	unshift @unblock_queue, [$cb, @_];
		556	$unblock_scheduler->ready;
		557	}
		558	}
		559
		560	=back
		561
329	=cut	562	=cut
330		563
331	1;	564	1;
332		565
333	=head1 BUGS/LIMITATIONS	566	=head1 BUGS/LIMITATIONS
334		567
335	- you must make very sure that no coro is still active on global	568	- you must make very sure that no coro is still active on global
336	destruction. very bad things might happen otherwise (usually segfaults).	569	destruction. very bad things might happen otherwise (usually segfaults).
337		570
338	- this module is not thread-safe. You should only ever use this module	571	- this module is not thread-safe. You should only ever use this module
339	from the same thread (this requirement might be losened in the future	572	from the same thread (this requirement might be loosened in the future
340	to allow per-thread schedulers, but Coro::State does not yet allow	573	to allow per-thread schedulers, but Coro::State does not yet allow
341	this).	574	this).
342		575
343	=head1 SEE ALSO	576	=head1 SEE ALSO
344		577

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Comparing Coro/Coro.pm (file contents): Revision 1.83 by root, Fri Nov 24 15:34:33 2006 UTC vs. Revision 1.132 by root, Thu Sep 20 22:53:23 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.83 by root, Fri Nov 24 15:34:33 2006 UTC vs.
Revision 1.132 by root, Thu Sep 20 22:53:23 2007 UTC