[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 1.137 by root, Wed Sep 26 19:26:48 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
		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	}
		159
		160	sub _do_trace {
		161	$current->{_trace_cb}->();
		162	}
137		163
138	# this coroutine is necessary because a coroutine	164	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	165	# cannot destroy itself.
140	my @destroy;	166	my @destroy;
		167	my $manager;
		168
141	my $manager; $manager = new Coro sub {	169	$manager = new Coro sub {
142	while () {	170	while () {
143	# by overwriting the state object with the manager we destroy it	171	(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) {	172	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		173
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;	174	&schedule;
160	}	175	}
161	};	176	};
		177	$manager->desc ("[coro manager]");
		178	$manager->prio (PRIO_MAX);
162		179
163	# static methods. not really.	180	# static methods. not really.
164		181
165	=back	182	=back
166		183
167	=head2 STATIC METHODS	184	=head2 STATIC METHODS
168		185
169	Static methods are actually functions that operate on the current process only.	186	Static methods are actually functions that operate on the current coroutine only.
170		187
171	=over 4	188	=over 4
172		189
173	=item async { ... } [@args...]	190	=item async { ... } [@args...]
174		191
175	Create a new asynchronous process and return it's process object	192	Create a new asynchronous coroutine and return it's coroutine object
176	(usually unused). When the sub returns the new process is automatically	193	(usually unused). When the sub returns the new coroutine is automatically
177	terminated.	194	terminated.
178		195
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	196	Calling C<exit> in a coroutine will do the same as calling exit outside
180		197	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	198	just as it would in the main program.
182	program.
183		199
184	# create a new coroutine that just prints its arguments	200	# create a new coroutine that just prints its arguments
185	async {	201	async {
186	print "@_\n";	202	print "@_\n";
187	} 1,2,3,4;	203	} 1,2,3,4;
188		204
189	=cut	205	=cut
190		206
191	sub async(&@) {	207	sub async(&@) {
192	my $pid = new Coro @_;	208	my $coro = new Coro @_;
193	$pid->ready;	209	$coro->ready;
194	$pid	210	$coro
		211	}
		212
		213	=item async_pool { ... } [@args...]
		214
		215	Similar to C<async>, but uses a coroutine pool, so you should not call
		216	terminate or join (although you are allowed to), and you get a coroutine
		217	that might have executed other code already (which can be good or bad :).
		218
		219	Also, the block is executed in an C<eval> context and a warning will be
		220	issued in case of an exception instead of terminating the program, as
		221	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		222	will not work in the expected way, unless you call terminate or cancel,
		223	which somehow defeats the purpose of pooling.
		224
		225	The priority will be reset to C<0> after each job, otherwise the coroutine
		226	will be re-used "as-is".
		227
		228	The pool size is limited to 8 idle coroutines (this can be adjusted by
		229	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		230	required.
		231
		232	If you are concerned about pooled coroutines growing a lot because a
		233	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		234	{ terminate }> once per second or so to slowly replenish the pool. In
		235	addition to that, when the stacks used by a handler grows larger than 16kb
		236	(adjustable with $Coro::POOL_RSS) it will also exit.
		237
		238	=cut
		239
		240	our $POOL_SIZE = 8;
		241	our $POOL_RSS = 16 * 1024;
		242	our @async_pool;
		243
		244	sub pool_handler {
		245	my $cb;
		246
		247	while () {
		248	eval {
		249	while () {
		250	_pool_1 $cb;
		251	&$cb;
		252	_pool_2 $cb;
		253	&schedule;
		254	}
		255	};
		256
		257	last if $@ eq "\3terminate\2\n";
		258	warn $@ if $@;
		259	}
		260	}
		261
		262	sub async_pool(&@) {
		263	# this is also inlined into the unlock_scheduler
		264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		265
		266	$coro->{_invoke} = [@_];
		267	$coro->ready;
		268
		269	$coro
195	}	270	}
196		271
197	=item schedule	272	=item schedule
198		273
199	Calls the scheduler. Please note that the current process will not be put	274	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	275	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	276	never be called again unless something else (e.g. an event handler) calls
202	ready.	277	ready.
203		278
204	The canonical way to wait on external events is this:	279	The canonical way to wait on external events is this:
205		280
206	{	281	{
207	# remember current process	282	# remember current coroutine
208	my $current = $Coro::current;	283	my $current = $Coro::current;
209		284
210	# register a hypothetical event handler	285	# register a hypothetical event handler
211	on_event_invoke sub {	286	on_event_invoke sub {
212	# wake up sleeping coroutine	287	# wake up sleeping coroutine
213	$current->ready;	288	$current->ready;
214	undef $current;	289	undef $current;
215	};	290	};
216		291
217	# call schedule until event occured.	292	# call schedule until event occurred.
218	# in case we are woken up for other reasons	293	# in case we are woken up for other reasons
219	# (current still defined), loop.	294	# (current still defined), loop.
220	Coro::schedule while $current;	295	Coro::schedule while $current;
221	}	296	}
222		297
223	=cut
224
225	=item cede	298	=item cede
226		299
227	"Cede" to other processes. This function puts the current process into the	300	"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	301	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.	302	current "timeslice" to other coroutines of the same or higher priority.
230		303
231	=cut	304	Returns true if at least one coroutine switch has happened.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to any
		309	coroutine, regardless of priority, once.
		310
		311	Returns true if at least one coroutine switch has happened.
232		312
233	=item terminate [arg...]	313	=item terminate [arg...]
234		314
235	Terminates the current process with the given status values (see L<cancel>).	315	Terminates the current coroutine with the given status values (see L<cancel>).
236		316
237	=cut	317	=cut
238		318
239	sub terminate {	319	sub terminate {
240	$current->cancel (@_);	320	$current->cancel (@_);
…		…
242		322
243	=back	323	=back
244		324
245	# dynamic methods	325	# dynamic methods
246		326
247	=head2 PROCESS METHODS	327	=head2 COROUTINE METHODS
248		328
249	These are the methods you can call on process objects.	329	These are the methods you can call on coroutine objects.
250		330
251	=over 4	331	=over 4
252		332
253	=item new Coro \&sub [, @args...]	333	=item new Coro \&sub [, @args...]
254		334
255	Create a new process and return it. When the sub returns the process	335	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	336	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	337	called. To make the coroutine run you must first put it into the ready queue
258	by calling the ready method.	338	by calling the ready method.
259		339
260	Calling C<exit> in a coroutine will not work correctly, so do not do that.	340	See C<async> for additional discussion.
261		341
262	=cut	342	=cut
263		343
264	sub _new_coro {	344	sub _run_coro {
265	terminate &{+shift};	345	terminate &{+shift};
266	}	346	}
267		347
268	sub new {	348	sub new {
269	my $class = shift;	349	my $class = shift;
270		350
271	$class->SUPER::new (\&_new_coro, @_)	351	$class->SUPER::new (\&_run_coro, @_)
272	}	352	}
273		353
274	=item $success = $process->ready	354	=item $success = $coroutine->ready
275		355
276	Put the given process into the ready queue (according to it's priority)	356	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	357	and return true. If the coroutine is already in the ready queue, do nothing
278	and return false.	358	and return false.
279		359
280	=item $is_ready = $process->is_ready	360	=item $is_ready = $coroutine->is_ready
281		361
282	Return wether the process is currently the ready queue or not,	362	Return wether the coroutine is currently the ready queue or not,
283		363
284	=item $process->cancel (arg...)	364	=item $coroutine->cancel (arg...)
285		365
286	Terminates the given process and makes it return the given arguments as	366	Terminates the given coroutine and makes it return the given arguments as
287	status (default: the empty list).	367	status (default: the empty list). Never returns if the coroutine is the
		368	current coroutine.
288		369
289	=cut	370	=cut
290		371
291	sub cancel {	372	sub cancel {
292	my $self = shift;	373	my $self = shift;
293	$self->{status} = [@_];	374	$self->{status} = [@_];
		375
		376	if ($current == $self) {
294	push @destroy, $self;	377	push @destroy, $self;
295	$manager->ready;	378	$manager->ready;
296	&schedule if $current == $self;	379	&schedule while 1;
		380	} else {
		381	$self->_cancel;
		382	}
297	}	383	}
298		384
299	=item $process->join	385	=item $coroutine->join
300		386
301	Wait until the coroutine terminates and return any values given to the	387	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	388	C<terminate> or C<cancel> functions. C<join> can be called multiple times
303	from multiple processes.	389	from multiple coroutine.
304		390
305	=cut	391	=cut
306		392
307	sub join {	393	sub join {
308	my $self = shift;	394	my $self = shift;
		395
309	unless ($self->{status}) {	396	unless ($self->{status}) {
310	push @{$self->{join}}, $current;	397	my $current = $current;
311	&schedule;	398
		399	push @{$self->{destroy_cb}}, sub {
		400	$current->ready;
		401	undef $current;
		402	};
		403
		404	&schedule while $current;
312	}	405	}
		406
313	wantarray ? @{$self->{status}} : $self->{status}[0];	407	wantarray ? @{$self->{status}} : $self->{status}[0];
314	}	408	}
315		409
		410	=item $coroutine->on_destroy (\&cb)
		411
		412	Registers a callback that is called when this coroutine gets destroyed,
		413	but before it is joined. The callback gets passed the terminate arguments,
		414	if any.
		415
		416	=cut
		417
		418	sub on_destroy {
		419	my ($self, $cb) = @_;
		420
		421	push @{ $self->{destroy_cb} }, $cb;
		422	}
		423
316	=item $oldprio = $process->prio ($newprio)	424	=item $oldprio = $coroutine->prio ($newprio)
317		425
318	Sets (or gets, if the argument is missing) the priority of the	426	Sets (or gets, if the argument is missing) the priority of the
319	process. Higher priority processes get run before lower priority	427	coroutine. Higher priority coroutines get run before lower priority
320	processes. Priorities are small signed integers (currently -4 .. +3),	428	coroutines. Priorities are small signed integers (currently -4 .. +3),
321	that you can refer to using PRIO_xxx constants (use the import tag :prio	429	that you can refer to using PRIO_xxx constants (use the import tag :prio
322	to get then):	430	to get then):
323		431
324	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	432	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
325	3 > 1 > 0 > -1 > -3 > -4	433	3 > 1 > 0 > -1 > -3 > -4
…		…
328	current->prio(PRIO_HIGH);	436	current->prio(PRIO_HIGH);
329		437
330	The idle coroutine ($Coro::idle) always has a lower priority than any	438	The idle coroutine ($Coro::idle) always has a lower priority than any
331	existing coroutine.	439	existing coroutine.
332		440
333	Changing the priority of the current process will take effect immediately,	441	Changing the priority of the current coroutine will take effect immediately,
334	but changing the priority of processes in the ready queue (but not	442	but changing the priority of coroutines in the ready queue (but not
335	running) will only take effect after the next schedule (of that	443	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.	444	coroutine). This is a bug that will be fixed in some future version.
337		445
338	=item $newprio = $process->nice ($change)	446	=item $newprio = $coroutine->nice ($change)
339		447
340	Similar to C<prio>, but subtract the given value from the priority (i.e.	448	Similar to C<prio>, but subtract the given value from the priority (i.e.
341	higher values mean lower priority, just as in unix).	449	higher values mean lower priority, just as in unix).
342		450
343	=item $olddesc = $process->desc ($newdesc)	451	=item $olddesc = $coroutine->desc ($newdesc)
344		452
345	Sets (or gets in case the argument is missing) the description for this	453	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.	454	coroutine. This is just a free-form string you can associate with a coroutine.
347		455
348	=cut	456	=cut
349		457
350	sub desc {	458	sub desc {
351	my $old = $_[0]{desc};	459	my $old = $_[0]{desc};
…		…
353	$old;	461	$old;
354	}	462	}
355		463
356	=back	464	=back
357		465
		466	=head2 GLOBAL FUNCTIONS
		467
		468	=over 4
		469
		470	=item Coro::nready
		471
		472	Returns the number of coroutines that are currently in the ready state,
		473	i.e. that can be switched to. The value C<0> means that the only runnable
		474	coroutine is the currently running one, so C<cede> would have no effect,
		475	and C<schedule> would cause a deadlock unless there is an idle handler
		476	that wakes up some coroutines.
		477
		478	=item my $guard = Coro::guard { ... }
		479
		480	This creates and returns a guard object. Nothing happens until the object
		481	gets destroyed, in which case the codeblock given as argument will be
		482	executed. This is useful to free locks or other resources in case of a
		483	runtime error or when the coroutine gets canceled, as in both cases the
		484	guard block will be executed. The guard object supports only one method,
		485	C<< ->cancel >>, which will keep the codeblock from being executed.
		486
		487	Example: set some flag and clear it again when the coroutine gets canceled
		488	or the function returns:
		489
		490	sub do_something {
		491	my $guard = Coro::guard { $busy = 0 };
		492	$busy = 1;
		493
		494	# do something that requires $busy to be true
		495	}
		496
		497	=cut
		498
		499	sub guard(&) {
		500	bless \(my $cb = $_[0]), "Coro::guard"
		501	}
		502
		503	sub Coro::guard::cancel {
		504	${$_[0]} = sub { };
		505	}
		506
		507	sub Coro::guard::DESTROY {
		508	${$_[0]}->();
		509	}
		510
		511
		512	=item unblock_sub { ... }
		513
		514	This utility function takes a BLOCK or code reference and "unblocks" it,
		515	returning the new coderef. This means that the new coderef will return
		516	immediately without blocking, returning nothing, while the original code
		517	ref will be called (with parameters) from within its own coroutine.
		518
		519	The reason this function exists is that many event libraries (such as the
		520	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		521	of thread-safety). This means you must not block within event callbacks,
		522	otherwise you might suffer from crashes or worse.
		523
		524	This function allows your callbacks to block by executing them in another
		525	coroutine where it is safe to block. One example where blocking is handy
		526	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		527	disk.
		528
		529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		530	creating event callbacks that want to block.
		531
		532	=cut
		533
		534	our @unblock_queue;
		535
		536	# we create a special coro because we want to cede,
		537	# to reduce pressure on the coro pool (because most callbacks
		538	# return immediately and can be reused) and because we cannot cede
		539	# inside an event callback.
		540	our $unblock_scheduler = new Coro sub {
		541	while () {
		542	while (my $cb = pop @unblock_queue) {
		543	# this is an inlined copy of async_pool
		544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		545
		546	$coro->{_invoke} = $cb;
		547	$coro->ready;
		548	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		549	}
		550	schedule; # sleep well
		551	}
		552	};
		553	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		554
		555	sub unblock_sub(&) {
		556	my $cb = shift;
		557
		558	sub {
		559	unshift @unblock_queue, [$cb, @_];
		560	$unblock_scheduler->ready;
		561	}
		562	}
		563
		564	=back
		565
358	=cut	566	=cut
359		567
360	1;	568	1;
361		569
362	=head1 BUGS/LIMITATIONS	570	=head1 BUGS/LIMITATIONS
363		571
364	- you must make very sure that no coro is still active on global	572	- you must make very sure that no coro is still active on global
365	destruction. very bad things might happen otherwise (usually segfaults).	573	destruction. very bad things might happen otherwise (usually segfaults).
366		574
367	- this module is not thread-safe. You should only ever use this module	575	- 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	576	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	577	to allow per-thread schedulers, but Coro::State does not yet allow
370	this).	578	this).
371		579
372	=head1 SEE ALSO	580	=head1 SEE ALSO
373		581

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 1.137 by root, Wed Sep 26 19:26:48 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 1.137 by root, Wed Sep 26 19:26:48 2007 UTC