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

Comparing Coro/Coro.pm (file contents):
Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 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 {
		164	$current->desc ("[coro manager]");
		165
139	while () {	166	while () {
140	# by overwriting the state object with the manager we destroy it	167	(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) {	168	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		169
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;	170	&schedule;
157	}	171	}
158	};	172	};
159		173
		174	$manager->prio (PRIO_MAX);
		175
160	# static methods. not really.	176	# static methods. not really.
161		177
162	=back	178	=back
163		179
164	=head2 STATIC METHODS	180	=head2 STATIC METHODS
165		181
166	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.
167		183
168	=over 4	184	=over 4
169		185
170	=item async { ... } [@args...]	186	=item async { ... } [@args...]
171		187
172	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	190	terminated.
175		191
176	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
177		193	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	194	just as it would in the main program.
179	program.
180		195
181	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
182	async {	197	async {
183	print "@_\n";	198	print "@_\n";
184	} 1,2,3,4;	199	} 1,2,3,4;
185		200
186	=cut	201	=cut
187		202
188	sub async(&@) {	203	sub async(&@) {
189	my $pid = new Coro @_;	204	my $coro = new Coro @_;
190	$pid->ready;	205	$coro->ready;
191	$pid	206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		230	terminate }> once per second or so to slowly replenish the pool.
		231
		232	=cut
		233
		234	our $POOL_SIZE = 8;
		235	our @pool;
		236
		237	sub pool_handler {
		238	while () {
		239	$current->{desc} = "[async_pool]";
		240
		241	eval {
		242	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		243	$cb->(@arg);
		244	};
		245	warn $@ if $@;
		246
		247	last if @pool >= $POOL_SIZE;
		248
		249	push @pool, $current;
		250	$current->{desc} = "[async_pool idle]";
		251	$current->save (Coro::State::SAVE_DEF);
		252	$current->prio (0);
		253	schedule;
		254	}
		255	}
		256
		257	sub async_pool(&@) {
		258	# this is also inlined into the unlock_scheduler
		259	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		260
		261	$coro->{_invoke} = [@_];
		262	$coro->ready;
		263
		264	$coro
192	}	265	}
193		266
194	=item schedule	267	=item schedule
195		268
196	Calls the scheduler. Please note that the current process will not be put	269	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	270	into the ready queue, so calling this function usually means you will
198	never be called again.	271	never be called again unless something else (e.g. an event handler) calls
		272	ready.
199		273
200	=cut	274	The canonical way to wait on external events is this:
		275
		276	{
		277	# remember current coroutine
		278	my $current = $Coro::current;
		279
		280	# register a hypothetical event handler
		281	on_event_invoke sub {
		282	# wake up sleeping coroutine
		283	$current->ready;
		284	undef $current;
		285	};
		286
		287	# call schedule until event occurred.
		288	# in case we are woken up for other reasons
		289	# (current still defined), loop.
		290	Coro::schedule while $current;
		291	}
201		292
202	=item cede	293	=item cede
203		294
204	"Cede" to other processes. This function puts the current process into the	295	"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	296	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.	297	current "timeslice" to other coroutines of the same or higher priority.
207		298
208	=cut	299	Returns true if at least one coroutine switch has happened.
		300
		301	=item Coro::cede_notself
		302
		303	Works like cede, but is not exported by default and will cede to any
		304	coroutine, regardless of priority, once.
		305
		306	Returns true if at least one coroutine switch has happened.
209		307
210	=item terminate [arg...]	308	=item terminate [arg...]
211		309
212	Terminates the current process with the given status values (see L<cancel>).	310	Terminates the current coroutine with the given status values (see L<cancel>).
213		311
214	=cut	312	=cut
215		313
216	sub terminate {	314	sub terminate {
217	$current->cancel (@_);	315	$current->cancel (@_);
…		…
219		317
220	=back	318	=back
221		319
222	# dynamic methods	320	# dynamic methods
223		321
224	=head2 PROCESS METHODS	322	=head2 COROUTINE METHODS
225		323
226	These are the methods you can call on process objects.	324	These are the methods you can call on coroutine objects.
227		325
228	=over 4	326	=over 4
229		327
230	=item new Coro \&sub [, @args...]	328	=item new Coro \&sub [, @args...]
231		329
232	Create a new process and return it. When the sub returns the process	330	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	331	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	332	called. To make the coroutine run you must first put it into the ready queue
235	by calling the ready method.	333	by calling the ready method.
236		334
237	Calling C<exit> in a coroutine will not work correctly, so do not do that.	335	See C<async> for additional discussion.
238		336
239	=cut	337	=cut
240		338
241	sub _new_coro {	339	sub _run_coro {
242	terminate &{+shift};	340	terminate &{+shift};
243	}	341	}
244		342
245	sub new {	343	sub new {
246	my $class = shift;	344	my $class = shift;
247		345
248	$class->SUPER::new (\&_new_coro, @_)	346	$class->SUPER::new (\&_run_coro, @_)
249	}	347	}
250		348
251	=item $process->ready	349	=item $success = $coroutine->ready
252		350
253	Put the given process into the ready queue.	351	Put the given coroutine into the ready queue (according to it's priority)
		352	and return true. If the coroutine is already in the ready queue, do nothing
		353	and return false.
254		354
255	=cut	355	=item $is_ready = $coroutine->is_ready
256		356
		357	Return wether the coroutine is currently the ready queue or not,
		358
257	=item $process->cancel (arg...)	359	=item $coroutine->cancel (arg...)
258		360
259	Terminates the given process and makes it return the given arguments as	361	Terminates the given coroutine and makes it return the given arguments as
260	status (default: the empty list).	362	status (default: the empty list). Never returns if the coroutine is the
		363	current coroutine.
261		364
262	=cut	365	=cut
263		366
264	sub cancel {	367	sub cancel {
265	my $self = shift;	368	my $self = shift;
266	$self->{status} = [@_];	369	$self->{status} = [@_];
		370
		371	if ($current == $self) {
267	push @destroy, $self;	372	push @destroy, $self;
268	$manager->ready;	373	$manager->ready;
269	&schedule if $current == $self;	374	&schedule while 1;
		375	} else {
		376	$self->_cancel;
		377	}
270	}	378	}
271		379
272	=item $process->join	380	=item $coroutine->join
273		381
274	Wait until the coroutine terminates and return any values given to the	382	Wait until the coroutine terminates and return any values given to the
275	C<terminate> or C<cancel> functions. C<join> can be called multiple times	383	C<terminate> or C<cancel> functions. C<join> can be called multiple times
276	from multiple processes.	384	from multiple coroutine.
277		385
278	=cut	386	=cut
279		387
280	sub join {	388	sub join {
281	my $self = shift;	389	my $self = shift;
		390
282	unless ($self->{status}) {	391	unless ($self->{status}) {
283	push @{$self->{join}}, $current;	392	my $current = $current;
284	&schedule;	393
		394	push @{$self->{destroy_cb}}, sub {
		395	$current->ready;
		396	undef $current;
		397	};
		398
		399	&schedule while $current;
285	}	400	}
		401
286	wantarray ? @{$self->{status}} : $self->{status}[0];	402	wantarray ? @{$self->{status}} : $self->{status}[0];
287	}	403	}
288		404
		405	=item $coroutine->on_destroy (\&cb)
		406
		407	Registers a callback that is called when this coroutine gets destroyed,
		408	but before it is joined. The callback gets passed the terminate arguments,
		409	if any.
		410
		411	=cut
		412
		413	sub on_destroy {
		414	my ($self, $cb) = @_;
		415
		416	push @{ $self->{destroy_cb} }, $cb;
		417	}
		418
289	=item $oldprio = $process->prio ($newprio)	419	=item $oldprio = $coroutine->prio ($newprio)
290		420
291	Sets (or gets, if the argument is missing) the priority of the	421	Sets (or gets, if the argument is missing) the priority of the
292	process. Higher priority processes get run before lower priority	422	coroutine. Higher priority coroutines get run before lower priority
293	processes. Priorities are small signed integers (currently -4 .. +3),	423	coroutines. Priorities are small signed integers (currently -4 .. +3),
294	that you can refer to using PRIO_xxx constants (use the import tag :prio	424	that you can refer to using PRIO_xxx constants (use the import tag :prio
295	to get then):	425	to get then):
296		426
297	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	427	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
298	3 > 1 > 0 > -1 > -3 > -4	428	3 > 1 > 0 > -1 > -3 > -4
…		…
301	current->prio(PRIO_HIGH);	431	current->prio(PRIO_HIGH);
302		432
303	The idle coroutine ($Coro::idle) always has a lower priority than any	433	The idle coroutine ($Coro::idle) always has a lower priority than any
304	existing coroutine.	434	existing coroutine.
305		435
306	Changing the priority of the current process will take effect immediately,	436	Changing the priority of the current coroutine will take effect immediately,
307	but changing the priority of processes in the ready queue (but not	437	but changing the priority of coroutines in the ready queue (but not
308	running) will only take effect after the next schedule (of that	438	running) will only take effect after the next schedule (of that
309	process). This is a bug that will be fixed in some future version.	439	coroutine). This is a bug that will be fixed in some future version.
310		440
311	=item $newprio = $process->nice ($change)	441	=item $newprio = $coroutine->nice ($change)
312		442
313	Similar to C<prio>, but subtract the given value from the priority (i.e.	443	Similar to C<prio>, but subtract the given value from the priority (i.e.
314	higher values mean lower priority, just as in unix).	444	higher values mean lower priority, just as in unix).
315		445
316	=item $olddesc = $process->desc ($newdesc)	446	=item $olddesc = $coroutine->desc ($newdesc)
317		447
318	Sets (or gets in case the argument is missing) the description for this	448	Sets (or gets in case the argument is missing) the description for this
319	process. This is just a free-form string you can associate with a process.	449	coroutine. This is just a free-form string you can associate with a coroutine.
320		450
321	=cut	451	=cut
322		452
323	sub desc {	453	sub desc {
324	my $old = $_[0]{desc};	454	my $old = $_[0]{desc};
…		…
326	$old;	456	$old;
327	}	457	}
328		458
329	=back	459	=back
330		460
		461	=head2 GLOBAL FUNCTIONS
		462
		463	=over 4
		464
		465	=item Coro::nready
		466
		467	Returns the number of coroutines that are currently in the ready state,
		468	i.e. that can be switched to. The value C<0> means that the only runnable
		469	coroutine is the currently running one, so C<cede> would have no effect,
		470	and C<schedule> would cause a deadlock unless there is an idle handler
		471	that wakes up some coroutines.
		472
		473	=item my $guard = Coro::guard { ... }
		474
		475	This creates and returns a guard object. Nothing happens until the object
		476	gets destroyed, in which case the codeblock given as argument will be
		477	executed. This is useful to free locks or other resources in case of a
		478	runtime error or when the coroutine gets canceled, as in both cases the
		479	guard block will be executed. The guard object supports only one method,
		480	C<< ->cancel >>, which will keep the codeblock from being executed.
		481
		482	Example: set some flag and clear it again when the coroutine gets canceled
		483	or the function returns:
		484
		485	sub do_something {
		486	my $guard = Coro::guard { $busy = 0 };
		487	$busy = 1;
		488
		489	# do something that requires $busy to be true
		490	}
		491
		492	=cut
		493
		494	sub guard(&) {
		495	bless \(my $cb = $_[0]), "Coro::guard"
		496	}
		497
		498	sub Coro::guard::cancel {
		499	${$_[0]} = sub { };
		500	}
		501
		502	sub Coro::guard::DESTROY {
		503	${$_[0]}->();
		504	}
		505
		506
		507	=item unblock_sub { ... }
		508
		509	This utility function takes a BLOCK or code reference and "unblocks" it,
		510	returning the new coderef. This means that the new coderef will return
		511	immediately without blocking, returning nothing, while the original code
		512	ref will be called (with parameters) from within its own coroutine.
		513
		514	The reason this function exists is that many event libraries (such as the
		515	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		516	of thread-safety). This means you must not block within event callbacks,
		517	otherwise you might suffer from crashes or worse.
		518
		519	This function allows your callbacks to block by executing them in another
		520	coroutine where it is safe to block. One example where blocking is handy
		521	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		522	disk.
		523
		524	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		525	creating event callbacks that want to block.
		526
		527	=cut
		528
		529	our @unblock_queue;
		530
		531	# we create a special coro because we want to cede,
		532	# to reduce pressure on the coro pool (because most callbacks
		533	# return immediately and can be reused) and because we cannot cede
		534	# inside an event callback.
		535	our $unblock_scheduler = async {
		536	$current->desc ("[unblock_sub scheduler]");
		537	while () {
		538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
		540	my $coro = (pop @pool or new Coro \&pool_handler);
		541
		542	$coro->{_invoke} = $cb;
		543	$coro->ready;
		544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		545	}
		546	schedule; # sleep well
		547	}
		548	};
		549
		550	sub unblock_sub(&) {
		551	my $cb = shift;
		552
		553	sub {
		554	unshift @unblock_queue, [$cb, @_];
		555	$unblock_scheduler->ready;
		556	}
		557	}
		558
		559	=back
		560
331	=cut	561	=cut
332		562
333	1;	563	1;
334		564
335	=head1 BUGS/LIMITATIONS	565	=head1 BUGS/LIMITATIONS
336		566
337	- you must make very sure that no coro is still active on global	567	- you must make very sure that no coro is still active on global
338	destruction. very bad things might happen otherwise (usually segfaults).	568	destruction. very bad things might happen otherwise (usually segfaults).
339		569
340	- this module is not thread-safe. You should only ever use this module	570	- this module is not thread-safe. You should only ever use this module
341	from the same thread (this requirement might be losened in the future	571	from the same thread (this requirement might be loosened in the future
342	to allow per-thread schedulers, but Coro::State does not yet allow	572	to allow per-thread schedulers, but Coro::State does not yet allow
343	this).	573	this).
344		574
345	=head1 SEE ALSO	575	=head1 SEE ALSO
346		576

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Comparing Coro/Coro.pm (file contents): Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs. Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC