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

Comparing Coro/Coro.pm (file contents):
Revision 1.90 by root, Thu Nov 30 18:21:14 2006 UTC vs.
Revision 1.128 by root, Wed Sep 19 21:39:15 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 $VERSION = '3.7';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($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
120	A callback that is called whenever the scheduler finds no ready coroutines	128	A callback that is called whenever the scheduler finds no ready coroutines
121	to run. The default implementation prints "FATAL: deadlock detected" and	129	to run. The default implementation prints "FATAL: deadlock detected" and
122	exits.	130	exits, because the program has no other way to continue.
123		131
124	This hook is overwritten by modules such as C<Coro::Timer> and	132	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	133	C<Coro::Event> to wait on an external event that hopefully wake up a
126	coroutine.	134	coroutine so the scheduler can run it.
		135
		136	Please note that if your callback recursively invokes perl (e.g. for event
		137	handlers), then it must be prepared to be called recursively.
127		138
128	=cut	139	=cut
129		140
130	$idle = sub {	141	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	142	require Carp;
132	exit (51);	143	Carp::croak ("FATAL: deadlock detected");
133	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
134		157
135	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	159	# cannot destroy itself.
137	my @destroy;	160	my @destroy;
		161	my $manager;
		162
138	my $manager; $manager = new Coro sub {	163	$manager = new Coro sub {
139	while () {	164	while () {
140	# by overwriting the state object with the manager we destroy it	165	(shift @destroy)->_cancel
141	# while still being able to schedule this coroutine (in case it has
142	# been readied multiple times. this is harmless since the manager
143	# can be called as many times as neccessary and will always
144	# remove itself from the runqueue
145	while (@destroy) {	166	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		167
150	# the next line destroys the coro state, but keeps the
151	# process itself intact (we basically make it a zombie
152	# process that always runs the manager thread, so it's possible
153	# to transfer() to this process).
154	$coro->_clone_state_from ($manager);
155	}
156	&schedule;	168	&schedule;
157	}	169	}
158	};	170	};
159		171
		172	$manager->prio (PRIO_MAX);
		173
160	# static methods. not really.	174	# static methods. not really.
161		175
162	=back	176	=back
163		177
164	=head2 STATIC METHODS	178	=head2 STATIC METHODS
165		179
166	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.
167		181
168	=over 4	182	=over 4
169		183
170	=item async { ... } [@args...]	184	=item async { ... } [@args...]
171		185
172	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	188	terminated.
175		189
176	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
177		191	the coroutine. Likewise, when the coroutine dies, the program will exit,
178	When the coroutine dies, the program will exit, just as in the main	192	just as it would in the main program.
179	program.
180		193
181	# create a new coroutine that just prints its arguments	194	# create a new coroutine that just prints its arguments
182	async {	195	async {
183	print "@_\n";	196	print "@_\n";
184	} 1,2,3,4;	197	} 1,2,3,4;
185		198
186	=cut	199	=cut
187		200
188	sub async(&@) {	201	sub async(&@) {
189	my $pid = new Coro @_;	202	my $coro = new Coro @_;
190	$pid->ready;	203	$coro->ready;
191	$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) \|\| do {
		255	my $coro = new Coro \&pool_handler;
		256	$coro->{desc} = "async_pool";
		257	$coro
		258	};
		259
		260	$coro->{_invoke} = [@_];
		261	$coro->ready;
		262
		263	$coro
192	}	264	}
193		265
194	=item schedule	266	=item schedule
195		267
196	Calls the scheduler. Please note that the current process will not be put	268	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	269	into the ready queue, so calling this function usually means you will
198	never be called again.	270	never be called again unless something else (e.g. an event handler) calls
		271	ready.
199		272
200	=cut	273	The canonical way to wait on external events is this:
		274
		275	{
		276	# remember current coroutine
		277	my $current = $Coro::current;
		278
		279	# register a hypothetical event handler
		280	on_event_invoke sub {
		281	# wake up sleeping coroutine
		282	$current->ready;
		283	undef $current;
		284	};
		285
		286	# call schedule until event occurred.
		287	# in case we are woken up for other reasons
		288	# (current still defined), loop.
		289	Coro::schedule while $current;
		290	}
201		291
202	=item cede	292	=item cede
203		293
204	"Cede" to other processes. This function puts the current process into the	294	"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	295	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.	296	current "timeslice" to other coroutines of the same or higher priority.
207		297
208	=cut	298	Returns true if at least one coroutine switch has happened.
		299
		300	=item Coro::cede_notself
		301
		302	Works like cede, but is not exported by default and will cede to any
		303	coroutine, regardless of priority, once.
		304
		305	Returns true if at least one coroutine switch has happened.
209		306
210	=item terminate [arg...]	307	=item terminate [arg...]
211		308
212	Terminates the current process with the given status values (see L<cancel>).	309	Terminates the current coroutine with the given status values (see L<cancel>).
213		310
214	=cut	311	=cut
215		312
216	sub terminate {	313	sub terminate {
217	$current->cancel (@_);	314	$current->cancel (@_);
…		…
219		316
220	=back	317	=back
221		318
222	# dynamic methods	319	# dynamic methods
223		320
224	=head2 PROCESS METHODS	321	=head2 COROUTINE METHODS
225		322
226	These are the methods you can call on process objects.	323	These are the methods you can call on coroutine objects.
227		324
228	=over 4	325	=over 4
229		326
230	=item new Coro \&sub [, @args...]	327	=item new Coro \&sub [, @args...]
231		328
232	Create a new process and return it. When the sub returns the process	329	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	330	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	331	called. To make the coroutine run you must first put it into the ready queue
235	by calling the ready method.	332	by calling the ready method.
236		333
237	Calling C<exit> in a coroutine will not work correctly, so do not do that.	334	See C<async> for additional discussion.
238		335
239	=cut	336	=cut
240		337
241	sub _new_coro {	338	sub _run_coro {
242	terminate &{+shift};	339	terminate &{+shift};
243	}	340	}
244		341
245	sub new {	342	sub new {
246	my $class = shift;	343	my $class = shift;
247		344
248	$class->SUPER::new (\&_new_coro, @_)	345	$class->SUPER::new (\&_run_coro, @_)
249	}	346	}
250		347
251	=item $success = $process->ready	348	=item $success = $coroutine->ready
252		349
253	Put the given process into the ready queue (according to it's priority)	350	Put the given coroutine into the ready queue (according to it's priority)
254	and return true. If the process is already in the ready queue, do nothing	351	and return true. If the coroutine is already in the ready queue, do nothing
255	and return false.	352	and return false.
256		353
257	=item $is_ready = $process->is_ready	354	=item $is_ready = $coroutine->is_ready
258		355
259	Return wether the process is currently the ready queue or not,	356	Return wether the coroutine is currently the ready queue or not,
260		357
261	=item $process->cancel (arg...)	358	=item $coroutine->cancel (arg...)
262		359
263	Terminates the given process and makes it return the given arguments as	360	Terminates the given coroutine and makes it return the given arguments as
264	status (default: the empty list).	361	status (default: the empty list). Never returns if the coroutine is the
		362	current coroutine.
265		363
266	=cut	364	=cut
267		365
268	sub cancel {	366	sub cancel {
269	my $self = shift;	367	my $self = shift;
270	$self->{status} = [@_];	368	$self->{status} = [@_];
		369
		370	if ($current == $self) {
271	push @destroy, $self;	371	push @destroy, $self;
272	$manager->ready;	372	$manager->ready;
273	&schedule if $current == $self;	373	&schedule while 1;
		374	} else {
		375	$self->_cancel;
		376	}
274	}	377	}
275		378
276	=item $process->join	379	=item $coroutine->join
277		380
278	Wait until the coroutine terminates and return any values given to the	381	Wait until the coroutine terminates and return any values given to the
279	C<terminate> or C<cancel> functions. C<join> can be called multiple times	382	C<terminate> or C<cancel> functions. C<join> can be called multiple times
280	from multiple processes.	383	from multiple coroutine.
281		384
282	=cut	385	=cut
283		386
284	sub join {	387	sub join {
285	my $self = shift;	388	my $self = shift;
		389
286	unless ($self->{status}) {	390	unless ($self->{status}) {
287	push @{$self->{join}}, $current;	391	my $current = $current;
288	&schedule;	392
		393	push @{$self->{destroy_cb}}, sub {
		394	$current->ready;
		395	undef $current;
		396	};
		397
		398	&schedule while $current;
289	}	399	}
		400
290	wantarray ? @{$self->{status}} : $self->{status}[0];	401	wantarray ? @{$self->{status}} : $self->{status}[0];
291	}	402	}
292		403
		404	=item $coroutine->on_destroy (\&cb)
		405
		406	Registers a callback that is called when this coroutine gets destroyed,
		407	but before it is joined. The callback gets passed the terminate arguments,
		408	if any.
		409
		410	=cut
		411
		412	sub on_destroy {
		413	my ($self, $cb) = @_;
		414
		415	push @{ $self->{destroy_cb} }, $cb;
		416	}
		417
293	=item $oldprio = $process->prio ($newprio)	418	=item $oldprio = $coroutine->prio ($newprio)
294		419
295	Sets (or gets, if the argument is missing) the priority of the	420	Sets (or gets, if the argument is missing) the priority of the
296	process. Higher priority processes get run before lower priority	421	coroutine. Higher priority coroutines get run before lower priority
297	processes. Priorities are small signed integers (currently -4 .. +3),	422	coroutines. Priorities are small signed integers (currently -4 .. +3),
298	that you can refer to using PRIO_xxx constants (use the import tag :prio	423	that you can refer to using PRIO_xxx constants (use the import tag :prio
299	to get then):	424	to get then):
300		425
301	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	426	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
302	3 > 1 > 0 > -1 > -3 > -4	427	3 > 1 > 0 > -1 > -3 > -4
…		…
305	current->prio(PRIO_HIGH);	430	current->prio(PRIO_HIGH);
306		431
307	The idle coroutine ($Coro::idle) always has a lower priority than any	432	The idle coroutine ($Coro::idle) always has a lower priority than any
308	existing coroutine.	433	existing coroutine.
309		434
310	Changing the priority of the current process will take effect immediately,	435	Changing the priority of the current coroutine will take effect immediately,
311	but changing the priority of processes in the ready queue (but not	436	but changing the priority of coroutines in the ready queue (but not
312	running) will only take effect after the next schedule (of that	437	running) will only take effect after the next schedule (of that
313	process). This is a bug that will be fixed in some future version.	438	coroutine). This is a bug that will be fixed in some future version.
314		439
315	=item $newprio = $process->nice ($change)	440	=item $newprio = $coroutine->nice ($change)
316		441
317	Similar to C<prio>, but subtract the given value from the priority (i.e.	442	Similar to C<prio>, but subtract the given value from the priority (i.e.
318	higher values mean lower priority, just as in unix).	443	higher values mean lower priority, just as in unix).
319		444
320	=item $olddesc = $process->desc ($newdesc)	445	=item $olddesc = $coroutine->desc ($newdesc)
321		446
322	Sets (or gets in case the argument is missing) the description for this	447	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.	448	coroutine. This is just a free-form string you can associate with a coroutine.
324		449
325	=cut	450	=cut
326		451
327	sub desc {	452	sub desc {
328	my $old = $_[0]{desc};	453	my $old = $_[0]{desc};
…		…
330	$old;	455	$old;
331	}	456	}
332		457
333	=back	458	=back
334		459
		460	=head2 GLOBAL FUNCTIONS
		461
		462	=over 4
		463
		464	=item Coro::nready
		465
		466	Returns the number of coroutines that are currently in the ready state,
		467	i.e. that can be switched to. The value C<0> means that the only runnable
		468	coroutine is the currently running one, so C<cede> would have no effect,
		469	and C<schedule> would cause a deadlock unless there is an idle handler
		470	that wakes up some coroutines.
		471
		472	=item my $guard = Coro::guard { ... }
		473
		474	This creates and returns a guard object. Nothing happens until the object
		475	gets destroyed, in which case the codeblock given as argument will be
		476	executed. This is useful to free locks or other resources in case of a
		477	runtime error or when the coroutine gets canceled, as in both cases the
		478	guard block will be executed. The guard object supports only one method,
		479	C<< ->cancel >>, which will keep the codeblock from being executed.
		480
		481	Example: set some flag and clear it again when the coroutine gets canceled
		482	or the function returns:
		483
		484	sub do_something {
		485	my $guard = Coro::guard { $busy = 0 };
		486	$busy = 1;
		487
		488	# do something that requires $busy to be true
		489	}
		490
		491	=cut
		492
		493	sub guard(&) {
		494	bless \(my $cb = $_[0]), "Coro::guard"
		495	}
		496
		497	sub Coro::guard::cancel {
		498	${$_[0]} = sub { };
		499	}
		500
		501	sub Coro::guard::DESTROY {
		502	${$_[0]}->();
		503	}
		504
		505
		506	=item unblock_sub { ... }
		507
		508	This utility function takes a BLOCK or code reference and "unblocks" it,
		509	returning the new coderef. This means that the new coderef will return
		510	immediately without blocking, returning nothing, while the original code
		511	ref will be called (with parameters) from within its own coroutine.
		512
		513	The reason this function exists is that many event libraries (such as the
		514	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		515	of thread-safety). This means you must not block within event callbacks,
		516	otherwise you might suffer from crashes or worse.
		517
		518	This function allows your callbacks to block by executing them in another
		519	coroutine where it is safe to block. One example where blocking is handy
		520	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		521	disk.
		522
		523	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		524	creating event callbacks that want to block.
		525
		526	=cut
		527
		528	our @unblock_queue;
		529
		530	# we create a special coro because we want to cede,
		531	# to reduce pressure on the coro pool (because most callbacks
		532	# return immediately and can be reused) and because we cannot cede
		533	# inside an event callback.
		534	our $unblock_scheduler = async {
		535	while () {
		536	while (my $cb = pop @unblock_queue) {
		537	# this is an inlined copy of async_pool
		538	my $coro = (pop @pool or new Coro \&pool_handler);
		539
		540	$coro->{_invoke} = $cb;
		541	$coro->ready;
		542	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		543	}
		544	schedule; # sleep well
		545	}
		546	};
		547
		548	sub unblock_sub(&) {
		549	my $cb = shift;
		550
		551	sub {
		552	unshift @unblock_queue, [$cb, @_];
		553	$unblock_scheduler->ready;
		554	}
		555	}
		556
		557	=back
		558
335	=cut	559	=cut
336		560
337	1;	561	1;
338		562
339	=head1 BUGS/LIMITATIONS	563	=head1 BUGS/LIMITATIONS
340		564
341	- you must make very sure that no coro is still active on global	565	- you must make very sure that no coro is still active on global
342	destruction. very bad things might happen otherwise (usually segfaults).	566	destruction. very bad things might happen otherwise (usually segfaults).
343		567
344	- this module is not thread-safe. You should only ever use this module	568	- this module is not thread-safe. You should only ever use this module
345	from the same thread (this requirement might be losened in the future	569	from the same thread (this requirement might be loosened in the future
346	to allow per-thread schedulers, but Coro::State does not yet allow	570	to allow per-thread schedulers, but Coro::State does not yet allow
347	this).	571	this).
348		572
349	=head1 SEE ALSO	573	=head1 SEE ALSO
350		574

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Comparing Coro/Coro.pm (file contents): Revision 1.90 by root, Thu Nov 30 18:21:14 2006 UTC vs. Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.90 by root, Thu Nov 30 18:21:14 2006 UTC vs.
Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC