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

Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.121 by root, Fri Apr 13 12:56:55 2007 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
18		18
19	cede;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
23	This module collection manages coroutines. Coroutines are similar to	23	This module collection manages coroutines. Coroutines are similar
24	threads but don't run in parallel.	24	to threads but don't run in parallel at the same time even on SMP
		25	machines. The specific flavor of coroutine use din this module also
		26	guarentees you that it will not switch between coroutines unless
		27	necessary, at easily-identified points in your program, so locking and
		28	parallel access are rarely an issue, making coroutine programming much
		29	safer than threads programming.
25		30
		31	(Perl, however, does not natively support real threads but instead does a
		32	very slow and memory-intensive emulation of processes using threads. This
		33	is a performance win on Windows machines, and a loss everywhere else).
		34
26	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	37	its own set of lexicals and its own set of perls most important global
29	important global variables.	38	variables.
30		39
31	=cut	40	=cut
32		41
33	package Coro;	42	package Coro;
34		43
…		…
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 $VERSION = '3.56';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($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.
		189
		190	Calling C<exit> in a coroutine will try to do the same as calling exit
		191	outside the coroutine, but this is experimental. It is best not to rely on
		192	exit doing any cleanups or even not crashing.
175		193
176	When the coroutine dies, the program will exit, just as in the main	194	When the coroutine dies, the program will exit, just as in the main
177	program.	195	program.
178		196
179	# create a new coroutine that just prints its arguments	197	# create a new coroutine that just prints its arguments
…		…
182	} 1,2,3,4;	200	} 1,2,3,4;
183		201
184	=cut	202	=cut
185		203
186	sub async(&@) {	204	sub async(&@) {
187	my $pid = new Coro @_;	205	my $coro = new Coro @_;
188	$pid->ready;	206	$coro->ready;
189	$pid	207	$coro
		208	}
		209
		210	=item async_pool { ... } [@args...]
		211
		212	Similar to C<async>, but uses a coroutine pool, so you should not call
		213	terminate or join (although you are allowed to), and you get a coroutine
		214	that might have executed other code already (which can be good or bad :).
		215
		216	Also, the block is executed in an C<eval> context and a warning will be
		217	issued in case of an exception instead of terminating the program, as
		218	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		219	will not work in the expected way, unless you call terminate or cancel,
		220	which somehow defeats the purpose of pooling.
		221
		222	The priority will be reset to C<0> after each job, otherwise the coroutine
		223	will be re-used "as-is".
		224
		225	The pool size is limited to 8 idle coroutines (this can be adjusted by
		226	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		227	required.
		228
		229	If you are concerned about pooled coroutines growing a lot because a
		230	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		231	terminate }> once per second or so to slowly replenish the pool.
		232
		233	=cut
		234
		235	our $POOL_SIZE = 8;
		236	our @pool;
		237
		238	sub pool_handler {
		239	while () {
		240	eval {
		241	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		242	$cb->(@arg);
		243	};
		244	warn $@ if $@;
		245
		246	last if @pool >= $POOL_SIZE;
		247	push @pool, $current;
		248
		249	$current->save (Coro::State::SAVE_DEF);
		250	$current->prio (0);
		251	schedule;
		252	}
		253	}
		254
		255	sub async_pool(&@) {
		256	# this is also inlined into the unlock_scheduler
		257	my $coro = (pop @pool or new Coro \&pool_handler);
		258
		259	$coro->{_invoke} = [@_];
		260	$coro->ready;
		261
		262	$coro
190	}	263	}
191		264
192	=item schedule	265	=item schedule
193		266
194	Calls the scheduler. Please note that the current process will not be put	267	Calls the scheduler. Please note that the current coroutine will not be put
195	into the ready queue, so calling this function usually means you will	268	into the ready queue, so calling this function usually means you will
196	never be called again.	269	never be called again unless something else (e.g. an event handler) calls
		270	ready.
197		271
198	=cut	272	The canonical way to wait on external events is this:
		273
		274	{
		275	# remember current coroutine
		276	my $current = $Coro::current;
		277
		278	# register a hypothetical event handler
		279	on_event_invoke sub {
		280	# wake up sleeping coroutine
		281	$current->ready;
		282	undef $current;
		283	};
		284
		285	# call schedule until event occured.
		286	# in case we are woken up for other reasons
		287	# (current still defined), loop.
		288	Coro::schedule while $current;
		289	}
199		290
200	=item cede	291	=item cede
201		292
202	"Cede" to other processes. This function puts the current process into the	293	"Cede" to other coroutines. This function puts the current coroutine into the
203	ready queue and calls C<schedule>, which has the effect of giving up the	294	ready queue and calls C<schedule>, which has the effect of giving up the
204	current "timeslice" to other coroutines of the same or higher priority.	295	current "timeslice" to other coroutines of the same or higher priority.
205		296
206	=cut	297	Returns true if at least one coroutine switch has happened.
		298
		299	=item Coro::cede_notself
		300
		301	Works like cede, but is not exported by default and will cede to any
		302	coroutine, regardless of priority, once.
		303
		304	Returns true if at least one coroutine switch has happened.
207		305
208	=item terminate [arg...]	306	=item terminate [arg...]
209		307
210	Terminates the current process with the given status values (see L<cancel>).	308	Terminates the current coroutine with the given status values (see L<cancel>).
211		309
212	=cut	310	=cut
213		311
214	sub terminate {	312	sub terminate {
215	$current->cancel (@_);	313	$current->cancel (@_);
…		…
217		315
218	=back	316	=back
219		317
220	# dynamic methods	318	# dynamic methods
221		319
222	=head2 PROCESS METHODS	320	=head2 COROUTINE METHODS
223		321
224	These are the methods you can call on process objects.	322	These are the methods you can call on coroutine objects.
225		323
226	=over 4	324	=over 4
227		325
228	=item new Coro \&sub [, @args...]	326	=item new Coro \&sub [, @args...]
229		327
230	Create a new process and return it. When the sub returns the process	328	Create a new coroutine and return it. When the sub returns the coroutine
231	automatically terminates as if C<terminate> with the returned values were	329	automatically terminates as if C<terminate> with the returned values were
232	called. To make the process run you must first put it into the ready queue	330	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	331	by calling the ready method.
234		332
235	=cut	333	See C<async> for additional discussion.
236		334
		335	=cut
		336
237	sub _new_coro {	337	sub _run_coro {
238	terminate &{+shift};	338	terminate &{+shift};
239	}	339	}
240		340
241	sub new {	341	sub new {
242	my $class = shift;	342	my $class = shift;
243		343
244	$class->SUPER::new (\&_new_coro, @_)	344	$class->SUPER::new (\&_run_coro, @_)
245	}	345	}
246		346
247	=item $process->ready	347	=item $success = $coroutine->ready
248		348
249	Put the given process into the ready queue.	349	Put the given coroutine into the ready queue (according to it's priority)
		350	and return true. If the coroutine is already in the ready queue, do nothing
		351	and return false.
250		352
251	=cut	353	=item $is_ready = $coroutine->is_ready
252		354
		355	Return wether the coroutine is currently the ready queue or not,
		356
253	=item $process->cancel (arg...)	357	=item $coroutine->cancel (arg...)
254		358
255	Terminates the given process and makes it return the given arguments as	359	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	360	status (default: the empty list). Never returns if the coroutine is the
		361	current coroutine.
257		362
258	=cut	363	=cut
259		364
260	sub cancel {	365	sub cancel {
261	my $self = shift;	366	my $self = shift;
262	$self->{status} = [@_];	367	$self->{status} = [@_];
		368
		369	if ($current == $self) {
263	push @destroy, $self;	370	push @destroy, $self;
264	$manager->ready;	371	$manager->ready;
265	&schedule if $current == $self;	372	&schedule while 1;
		373	} else {
		374	$self->_cancel;
		375	}
266	}	376	}
267		377
268	=item $process->join	378	=item $coroutine->join
269		379
270	Wait until the coroutine terminates and return any values given to the	380	Wait until the coroutine terminates and return any values given to the
271	C<terminate> or C<cancel> functions. C<join> can be called multiple times	381	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	382	from multiple coroutine.
273		383
274	=cut	384	=cut
275		385
276	sub join {	386	sub join {
277	my $self = shift;	387	my $self = shift;
		388
278	unless ($self->{status}) {	389	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	390	my $current = $current;
280	&schedule;	391
		392	push @{$self->{destroy_cb}}, sub {
		393	$current->ready;
		394	undef $current;
		395	};
		396
		397	&schedule while $current;
281	}	398	}
		399
282	wantarray ? @{$self->{status}} : $self->{status}[0];	400	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	401	}
284		402
		403	=item $coroutine->on_destroy (\&cb)
		404
		405	Registers a callback that is called when this coroutine gets destroyed,
		406	but before it is joined. The callback gets passed the terminate arguments,
		407	if any.
		408
		409	=cut
		410
		411	sub on_destroy {
		412	my ($self, $cb) = @_;
		413
		414	push @{ $self->{destroy_cb} }, $cb;
		415	}
		416
285	=item $oldprio = $process->prio ($newprio)	417	=item $oldprio = $coroutine->prio ($newprio)
286		418
287	Sets (or gets, if the argument is missing) the priority of the	419	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	420	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	421	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	422	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	423	to get then):
292		424
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	425	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	426	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	429	current->prio(PRIO_HIGH);
298		430
299	The idle coroutine ($Coro::idle) always has a lower priority than any	431	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	432	existing coroutine.
301		433
302	Changing the priority of the current process will take effect immediately,	434	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	435	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	436	running) will only take effect after the next schedule (of that
305	process). This is a bug that will be fixed in some future version.	437	coroutine). This is a bug that will be fixed in some future version.
306		438
307	=item $newprio = $process->nice ($change)	439	=item $newprio = $coroutine->nice ($change)
308		440
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	441	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	442	higher values mean lower priority, just as in unix).
311		443
312	=item $olddesc = $process->desc ($newdesc)	444	=item $olddesc = $coroutine->desc ($newdesc)
313		445
314	Sets (or gets in case the argument is missing) the description for this	446	Sets (or gets in case the argument is missing) the description for this
315	process. This is just a free-form string you can associate with a process.	447	coroutine. This is just a free-form string you can associate with a coroutine.
316		448
317	=cut	449	=cut
318		450
319	sub desc {	451	sub desc {
320	my $old = $_[0]{desc};	452	my $old = $_[0]{desc};
…		…
322	$old;	454	$old;
323	}	455	}
324		456
325	=back	457	=back
326		458
		459	=head2 GLOBAL FUNCTIONS
		460
		461	=over 4
		462
		463	=item Coro::nready
		464
		465	Returns the number of coroutines that are currently in the ready state,
		466	i.e. that can be swicthed to. The value C<0> means that the only runnable
		467	coroutine is the currently running one, so C<cede> would have no effect,
		468	and C<schedule> would cause a deadlock unless there is an idle handler
		469	that wakes up some coroutines.
		470
		471	=item my $guard = Coro::guard { ... }
		472
		473	This creates and returns a guard object. Nothing happens until the object
		474	gets destroyed, in which case the codeblock given as argument will be
		475	executed. This is useful to free locks or other resources in case of a
		476	runtime error or when the coroutine gets canceled, as in both cases the
		477	guard block will be executed. The guard object supports only one method,
		478	C<< ->cancel >>, which will keep the codeblock from being executed.
		479
		480	Example: set some flag and clear it again when the coroutine gets canceled
		481	or the function returns:
		482
		483	sub do_something {
		484	my $guard = Coro::guard { $busy = 0 };
		485	$busy = 1;
		486
		487	# do something that requires $busy to be true
		488	}
		489
		490	=cut
		491
		492	sub guard(&) {
		493	bless \(my $cb = $_[0]), "Coro::guard"
		494	}
		495
		496	sub Coro::guard::cancel {
		497	${$_[0]} = sub { };
		498	}
		499
		500	sub Coro::guard::DESTROY {
		501	${$_[0]}->();
		502	}
		503
		504
		505	=item unblock_sub { ... }
		506
		507	This utility function takes a BLOCK or code reference and "unblocks" it,
		508	returning the new coderef. This means that the new coderef will return
		509	immediately without blocking, returning nothing, while the original code
		510	ref will be called (with parameters) from within its own coroutine.
		511
		512	The reason this fucntion exists is that many event libraries (such as the
		513	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		514	of thread-safety). This means you must not block within event callbacks,
		515	otherwise you might suffer from crashes or worse.
		516
		517	This function allows your callbacks to block by executing them in another
		518	coroutine where it is safe to block. One example where blocking is handy
		519	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		520	disk.
		521
		522	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		523	creating event callbacks that want to block.
		524
		525	=cut
		526
		527	our @unblock_queue;
		528
		529	# we create a special coro because we want to cede,
		530	# to reduce pressure on the coro pool (because most callbacks
		531	# return immediately and can be reused) and because we cannot cede
		532	# inside an event callback.
		533	our $unblock_scheduler = async {
		534	while () {
		535	while (my $cb = pop @unblock_queue) {
		536	# this is an inlined copy of async_pool
		537	my $coro = (pop @pool or new Coro \&pool_handler);
		538
		539	$coro->{_invoke} = $cb;
		540	$coro->ready;
		541	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		542	}
		543	schedule; # sleep well
		544	}
		545	};
		546
		547	sub unblock_sub(&) {
		548	my $cb = shift;
		549
		550	sub {
		551	unshift @unblock_queue, [$cb, @_];
		552	$unblock_scheduler->ready;
		553	}
		554	}
		555
		556	=back
		557
327	=cut	558	=cut
328		559
329	1;	560	1;
330		561
331	=head1 BUGS/LIMITATIONS	562	=head1 BUGS/LIMITATIONS

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Comparing Coro/Coro.pm (file contents): Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs. Revision 1.121 by root, Fri Apr 13 12:56:55 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.121 by root, Fri Apr 13 12:56:55 2007 UTC