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

Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.140 by root, Thu Sep 27 16:25:10 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 $VERSION = '3.8';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
…		…
129	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively.
130		140
131	=cut	141	=cut
132		142
133	$idle = sub {	143	$idle = sub {
134	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
135	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
136	};	146	};
		147
		148	sub _cancel {
		149	my ($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	}
137		159
138	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	161	# cannot destroy itself.
140	my @destroy;	162	my @destroy;
		163	my $manager;
		164
141	my $manager; $manager = new Coro sub {	165	$manager = new Coro sub {
142	while () {	166	while () {
143	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
144	# while still being able to schedule this coroutine (in case it has
145	# been readied multiple times. this is harmless since the manager
146	# can be called as many times as neccessary and will always
147	# remove itself from the runqueue
148	while (@destroy) {	168	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		169
153	# the next line destroys the coro state, but keeps the
154	# process itself intact (we basically make it a zombie
155	# process that always runs the manager thread, so it's possible
156	# to transfer() to this process).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	170	&schedule;
160	}	171	}
161	};	172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
162		175
163	# static methods. not really.	176	# static methods. not really.
164		177
165	=back	178	=back
166		179
167	=head2 STATIC METHODS	180	=head2 STATIC METHODS
168		181
169	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.
170		183
171	=over 4	184	=over 4
172		185
173	=item async { ... } [@args...]	186	=item async { ... } [@args...]
174		187
175	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	190	terminated.
178		191
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	192	Calling C<exit> in a coroutine will do the same as calling exit outside
180		193	the coroutine. Likewise, when the coroutine dies, the program will exit,
181	When the coroutine dies, the program will exit, just as in the main	194	just as it would in the main program.
182	program.
183		195
184	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
185	async {	197	async {
186	print "@_\n";	198	print "@_\n";
187	} 1,2,3,4;	199	} 1,2,3,4;
188		200
189	=cut	201	=cut
190		202
191	sub async(&@) {	203	sub async(&@) {
192	my $pid = new Coro @_;	204	my $coro = new Coro @_;
193	$pid->ready;	205	$coro->ready;
194	$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. In
		231	addition to that, when the stacks used by a handler grows larger than 16kb
		232	(adjustable with $Coro::POOL_RSS) it will also exit.
		233
		234	=cut
		235
		236	our $POOL_SIZE = 8;
		237	our $POOL_RSS = 16 * 1024;
		238	our @async_pool;
		239
		240	sub pool_handler {
		241	my $cb;
		242
		243	while () {
		244	eval {
		245	while () {
		246	_pool_1 $cb;
		247	&$cb;
		248	_pool_2 $cb;
		249	&schedule;
		250	}
		251	};
		252
		253	last if $@ eq "\3terminate\2\n";
		254	warn $@ if $@;
		255	}
		256	}
		257
		258	sub async_pool(&@) {
		259	# this is also inlined into the unlock_scheduler
		260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		261
		262	$coro->{_invoke} = [@_];
		263	$coro->ready;
		264
		265	$coro
195	}	266	}
196		267
197	=item schedule	268	=item schedule
198		269
199	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
200	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
201	never be called again unless something else (e.g. an event handler) calls	272	never be called again unless something else (e.g. an event handler) calls
202	ready.	273	ready.
203		274
204	The canonical way to wait on external events is this:	275	The canonical way to wait on external events is this:
205		276
206	{	277	{
207	# remember current process	278	# remember current coroutine
208	my $current = $Coro::current;	279	my $current = $Coro::current;
209		280
210	# register a hypothetical event handler	281	# register a hypothetical event handler
211	on_event_invoke sub {	282	on_event_invoke sub {
212	# wake up sleeping coroutine	283	# wake up sleeping coroutine
213	$current->ready;	284	$current->ready;
214	undef $current;	285	undef $current;
215	};	286	};
216		287
217	# call schedule until event occured.	288	# call schedule until event occurred.
218	# in case we are woken up for other reasons	289	# in case we are woken up for other reasons
219	# (current still defined), loop.	290	# (current still defined), loop.
220	Coro::schedule while $current;	291	Coro::schedule while $current;
221	}	292	}
222		293
223	=cut
224
225	=item cede	294	=item cede
226		295
227	"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
228	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
229	current "timeslice" to other coroutines of the same or higher priority.	298	current "timeslice" to other coroutines of the same or higher priority.
230		299
231	=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.
232		308
233	=item terminate [arg...]	309	=item terminate [arg...]
234		310
235	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>).
236		312
237	=cut	313	=cut
238		314
239	sub terminate {	315	sub terminate {
240	$current->cancel (@_);	316	$current->cancel (@_);
…		…
242		318
243	=back	319	=back
244		320
245	# dynamic methods	321	# dynamic methods
246		322
247	=head2 PROCESS METHODS	323	=head2 COROUTINE METHODS
248		324
249	These are the methods you can call on process objects.	325	These are the methods you can call on coroutine objects.
250		326
251	=over 4	327	=over 4
252		328
253	=item new Coro \&sub [, @args...]	329	=item new Coro \&sub [, @args...]
254		330
255	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
256	automatically terminates as if C<terminate> with the returned values were	332	automatically terminates as if C<terminate> with the returned values were
257	called. To make the process run you must first put it into the ready queue	333	called. To make the coroutine run you must first put it into the ready queue
258	by calling the ready method.	334	by calling the ready method.
259		335
260	Calling C<exit> in a coroutine will not work correctly, so do not do that.	336	See C<async> for additional discussion.
261		337
262	=cut	338	=cut
263		339
264	sub _new_coro {	340	sub _run_coro {
265	terminate &{+shift};	341	terminate &{+shift};
266	}	342	}
267		343
268	sub new {	344	sub new {
269	my $class = shift;	345	my $class = shift;
270		346
271	$class->SUPER::new (\&_new_coro, @_)	347	$class->SUPER::new (\&_run_coro, @_)
272	}	348	}
273		349
274	=item $success = $process->ready	350	=item $success = $coroutine->ready
275		351
276	Put the given process into the ready queue (according to it's priority)	352	Put the given coroutine into the ready queue (according to it's priority)
277	and return true. If the process is already in the ready queue, do nothing	353	and return true. If the coroutine is already in the ready queue, do nothing
278	and return false.	354	and return false.
279		355
280	=item $is_ready = $process->is_ready	356	=item $is_ready = $coroutine->is_ready
281		357
282	Return wether the process is currently the ready queue or not,	358	Return wether the coroutine is currently the ready queue or not,
283		359
284	=item $process->cancel (arg...)	360	=item $coroutine->cancel (arg...)
285		361
286	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
287	status (default: the empty list).	363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
288		365
289	=cut	366	=cut
290		367
291	sub cancel {	368	sub cancel {
292	my $self = shift;	369	my $self = shift;
293	$self->{status} = [@_];	370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
294	push @destroy, $self;	373	push @destroy, $self;
295	$manager->ready;	374	$manager->ready;
296	&schedule if $current == $self;	375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
297	}	379	}
298		380
299	=item $process->join	381	=item $coroutine->join
300		382
301	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
302	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
303	from multiple processes.	385	from multiple coroutine.
304		386
305	=cut	387	=cut
306		388
307	sub join {	389	sub join {
308	my $self = shift;	390	my $self = shift;
		391
309	unless ($self->{status}) {	392	unless ($self->{status}) {
310	push @{$self->{join}}, $current;	393	my $current = $current;
311	&schedule;	394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
312	}	401	}
		402
313	wantarray ? @{$self->{status}} : $self->{status}[0];	403	wantarray ? @{$self->{status}} : $self->{status}[0];
314	}	404	}
315		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
316	=item $oldprio = $process->prio ($newprio)	420	=item $oldprio = $coroutine->prio ($newprio)
317		421
318	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
319	process. Higher priority processes get run before lower priority	423	coroutine. Higher priority coroutines get run before lower priority
320	processes. Priorities are small signed integers (currently -4 .. +3),	424	coroutines. Priorities are small signed integers (currently -4 .. +3),
321	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
322	to get then):	426	to get then):
323		427
324	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
325	3 > 1 > 0 > -1 > -3 > -4	429	3 > 1 > 0 > -1 > -3 > -4
…		…
328	current->prio(PRIO_HIGH);	432	current->prio(PRIO_HIGH);
329		433
330	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
331	existing coroutine.	435	existing coroutine.
332		436
333	Changing the priority of the current process will take effect immediately,	437	Changing the priority of the current coroutine will take effect immediately,
334	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
335	running) will only take effect after the next schedule (of that	439	running) will only take effect after the next schedule (of that
336	process). This is a bug that will be fixed in some future version.	440	coroutine). This is a bug that will be fixed in some future version.
337		441
338	=item $newprio = $process->nice ($change)	442	=item $newprio = $coroutine->nice ($change)
339		443
340	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.
341	higher values mean lower priority, just as in unix).	445	higher values mean lower priority, just as in unix).
342		446
343	=item $olddesc = $process->desc ($newdesc)	447	=item $olddesc = $coroutine->desc ($newdesc)
344		448
345	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
346	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.
347		451
348	=cut	452	=cut
349		453
350	sub desc {	454	sub desc {
351	my $old = $_[0]{desc};	455	my $old = $_[0]{desc};
…		…
353	$old;	457	$old;
354	}	458	}
355		459
356	=back	460	=back
357		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 @async_pool) \|\| 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
358	=cut	562	=cut
359		563
360	1;	564	1;
361		565
362	=head1 BUGS/LIMITATIONS	566	=head1 BUGS/LIMITATIONS
363		567
364	- 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
365	destruction. very bad things might happen otherwise (usually segfaults).	569	destruction. very bad things might happen otherwise (usually segfaults).
366		570
367	- 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
368	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
369	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
370	this).	574	this).
371		575
372	=head1 SEE ALSO	576	=head1 SEE ALSO
373		577

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs. Revision 1.140 by root, Thu Sep 27 16:25:10 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.140 by root, Thu Sep 27 16:25:10 2007 UTC