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

Comparing Coro/Coro.pm (file contents):
Revision 1.87 by root, Sun Nov 26 02:16:19 2006 UTC vs.
Revision 1.107 by root, Fri Jan 5 18:25:51 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 = '2.5';	55	our $VERSION = '3.3';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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 not work correctly, so do not do that.
175		191
176	When the coroutine dies, the program will exit, just as in the main	192	When the coroutine dies, the program will exit, just as in the main
177	program.	193	program.
178		194
179	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
…		…
182	} 1,2,3,4;	198	} 1,2,3,4;
183		199
184	=cut	200	=cut
185		201
186	sub async(&@) {	202	sub async(&@) {
187	my $pid = new Coro @_;	203	my $coro = new Coro @_;
188	$pid->ready;	204	$coro->ready;
189	$pid	205	$coro
		206	}
		207
		208	=item async_pool { ... } [@args...]
		209
		210	Similar to C<async>, but uses a coroutine pool, so you should not call
		211	terminate or join (although you are allowed to), and you get a coroutine
		212	that might have executed other code already (which can be good or bad :).
		213
		214	Also, the block is executed in an C<eval> context and a warning will be
		215	issued in case of an exception instead of terminating the program, as C<async> does.
		216
		217	The priority will be reset to C<0> after each job, otherwise the coroutine
		218	will be re-used "as-is".
		219
		220	The pool size is limited to 8 idle coroutines (this can be adjusted by
		221	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		222	required.
		223
		224	If you are concerned about pooled coroutines growing a lot because a
		225	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		226	terminate }> once per second or so to slowly replenish the pool.
		227
		228	=cut
		229
		230	our $POOL_SIZE = 8;
		231	our @pool;
		232
		233	sub pool_handler {
		234	while () {
		235	my ($cb, @arg) = @{ delete $current->{_invoke} };
		236
		237	eval {
		238	$cb->(@arg);
		239	};
		240	warn $@ if $@;
		241
		242	last if @pool >= $POOL_SIZE;
		243	push @pool, $current;
		244
		245	$current->prio (0);
		246	schedule;
		247	}
		248	}
		249
		250	sub async_pool(&@) {
		251	# this is also inlined into the unlock_scheduler
		252	my $coro = (pop @pool or new Coro \&pool_handler);
		253
		254	$coro->{_invoke} = [@_];
		255	$coro->ready;
		256
		257	$coro
190	}	258	}
191		259
192	=item schedule	260	=item schedule
193		261
194	Calls the scheduler. Please note that the current process will not be put	262	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	263	into the ready queue, so calling this function usually means you will
196	never be called again.	264	never be called again unless something else (e.g. an event handler) calls
		265	ready.
197		266
198	=cut	267	The canonical way to wait on external events is this:
		268
		269	{
		270	# remember current coroutine
		271	my $current = $Coro::current;
		272
		273	# register a hypothetical event handler
		274	on_event_invoke sub {
		275	# wake up sleeping coroutine
		276	$current->ready;
		277	undef $current;
		278	};
		279
		280	# call schedule until event occured.
		281	# in case we are woken up for other reasons
		282	# (current still defined), loop.
		283	Coro::schedule while $current;
		284	}
199		285
200	=item cede	286	=item cede
201		287
202	"Cede" to other processes. This function puts the current process into the	288	"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	289	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.	290	current "timeslice" to other coroutines of the same or higher priority.
205		291
206	=cut	292	Returns true if at least one coroutine switch has happened.
		293
		294	=item Coro::cede_notself
		295
		296	Works like cede, but is not exported by default and will cede to any
		297	coroutine, regardless of priority, once.
		298
		299	Returns true if at least one coroutine switch has happened.
207		300
208	=item terminate [arg...]	301	=item terminate [arg...]
209		302
210	Terminates the current process with the given status values (see L<cancel>).	303	Terminates the current coroutine with the given status values (see L<cancel>).
211		304
212	=cut	305	=cut
213		306
214	sub terminate {	307	sub terminate {
215	$current->cancel (@_);	308	$current->cancel (@_);
…		…
217		310
218	=back	311	=back
219		312
220	# dynamic methods	313	# dynamic methods
221		314
222	=head2 PROCESS METHODS	315	=head2 COROUTINE METHODS
223		316
224	These are the methods you can call on process objects.	317	These are the methods you can call on coroutine objects.
225		318
226	=over 4	319	=over 4
227		320
228	=item new Coro \&sub [, @args...]	321	=item new Coro \&sub [, @args...]
229		322
230	Create a new process and return it. When the sub returns the process	323	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	324	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	325	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	326	by calling the ready method.
234		327
235	=cut	328	Calling C<exit> in a coroutine will not work correctly, so do not do that.
236		329
		330	=cut
		331
237	sub _new_coro {	332	sub _run_coro {
238	terminate &{+shift};	333	terminate &{+shift};
239	}	334	}
240		335
241	sub new {	336	sub new {
242	my $class = shift;	337	my $class = shift;
243		338
244	$class->SUPER::new (\&_new_coro, @_)	339	$class->SUPER::new (\&_run_coro, @_)
245	}	340	}
246		341
247	=item $process->ready	342	=item $success = $coroutine->ready
248		343
249	Put the given process into the ready queue.	344	Put the given coroutine into the ready queue (according to it's priority)
		345	and return true. If the coroutine is already in the ready queue, do nothing
		346	and return false.
250		347
251	=cut	348	=item $is_ready = $coroutine->is_ready
252		349
		350	Return wether the coroutine is currently the ready queue or not,
		351
253	=item $process->cancel (arg...)	352	=item $coroutine->cancel (arg...)
254		353
255	Terminates the given process and makes it return the given arguments as	354	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	355	status (default: the empty list). Never returns if the coroutine is the
		356	current coroutine.
257		357
258	=cut	358	=cut
259		359
260	sub cancel {	360	sub cancel {
261	my $self = shift;	361	my $self = shift;
262	$self->{status} = [@_];	362	$self->{status} = [@_];
		363
		364	if ($current == $self) {
263	push @destroy, $self;	365	push @destroy, $self;
264	$manager->ready;	366	$manager->ready;
265	&schedule if $current == $self;	367	&schedule while 1;
		368	} else {
		369	$self->_cancel;
		370	}
266	}	371	}
267		372
268	=item $process->join	373	=item $coroutine->join
269		374
270	Wait until the coroutine terminates and return any values given to the	375	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	376	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	377	from multiple coroutine.
273		378
274	=cut	379	=cut
275		380
276	sub join {	381	sub join {
277	my $self = shift;	382	my $self = shift;
		383
278	unless ($self->{status}) {	384	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	385	my $current = $current;
280	&schedule;	386
		387	push @{$self->{destroy_cb}}, sub {
		388	$current->ready;
		389	undef $current;
		390	};
		391
		392	&schedule while $current;
281	}	393	}
		394
282	wantarray ? @{$self->{status}} : $self->{status}[0];	395	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	396	}
284		397
		398	=item $coroutine->on_destroy (\&cb)
		399
		400	Registers a callback that is called when this coroutine gets destroyed,
		401	but before it is joined. The callback gets passed the terminate arguments,
		402	if any.
		403
		404	=cut
		405
		406	sub on_destroy {
		407	my ($self, $cb) = @_;
		408
		409	push @{ $self->{destroy_cb} }, $cb;
		410	}
		411
285	=item $oldprio = $process->prio ($newprio)	412	=item $oldprio = $coroutine->prio ($newprio)
286		413
287	Sets (or gets, if the argument is missing) the priority of the	414	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	415	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	416	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	417	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	418	to get then):
292		419
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	420	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	421	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	424	current->prio(PRIO_HIGH);
298		425
299	The idle coroutine ($Coro::idle) always has a lower priority than any	426	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	427	existing coroutine.
301		428
302	Changing the priority of the current process will take effect immediately,	429	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	430	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	431	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.	432	coroutine). This is a bug that will be fixed in some future version.
306		433
307	=item $newprio = $process->nice ($change)	434	=item $newprio = $coroutine->nice ($change)
308		435
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	436	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	437	higher values mean lower priority, just as in unix).
311		438
312	=item $olddesc = $process->desc ($newdesc)	439	=item $olddesc = $coroutine->desc ($newdesc)
313		440
314	Sets (or gets in case the argument is missing) the description for this	441	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.	442	coroutine. This is just a free-form string you can associate with a coroutine.
316		443
317	=cut	444	=cut
318		445
319	sub desc {	446	sub desc {
320	my $old = $_[0]{desc};	447	my $old = $_[0]{desc};
…		…
322	$old;	449	$old;
323	}	450	}
324		451
325	=back	452	=back
326		453
		454	=head2 GLOBAL FUNCTIONS
		455
		456	=over 4
		457
		458	=item Coro::nready
		459
		460	Returns the number of coroutines that are currently in the ready state,
		461	i.e. that can be swicthed to. The value C<0> means that the only runnable
		462	coroutine is the currently running one, so C<cede> would have no effect,
		463	and C<schedule> would cause a deadlock unless there is an idle handler
		464	that wakes up some coroutines.
		465
		466	=item my $guard = Coro::guard { ... }
		467
		468	This creates and returns a guard object. Nothing happens until the objetc
		469	gets destroyed, in which case the codeblock given as argument will be
		470	executed. This is useful to free locks or other resources in case of a
		471	runtime error or when the coroutine gets canceled, as in both cases the
		472	guard block will be executed. The guard object supports only one method,
		473	C<< ->cancel >>, which will keep the codeblock from being executed.
		474
		475	Example: set some flag and clear it again when the coroutine gets canceled
		476	or the function returns:
		477
		478	sub do_something {
		479	my $guard = Coro::guard { $busy = 0 };
		480	$busy = 1;
		481
		482	# do something that requires $busy to be true
		483	}
		484
		485	=cut
		486
		487	sub guard(&) {
		488	bless \(my $cb = $_[0]), "Coro::guard"
		489	}
		490
		491	sub Coro::guard::cancel {
		492	${$_[0]} = sub { };
		493	}
		494
		495	sub Coro::guard::DESTROY {
		496	${$_[0]}->();
		497	}
		498
		499
		500	=item unblock_sub { ... }
		501
		502	This utility function takes a BLOCK or code reference and "unblocks" it,
		503	returning the new coderef. This means that the new coderef will return
		504	immediately without blocking, returning nothing, while the original code
		505	ref will be called (with parameters) from within its own coroutine.
		506
		507	The reason this fucntion exists is that many event libraries (such as the
		508	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		509	of thread-safety). This means you must not block within event callbacks,
		510	otherwise you might suffer from crashes or worse.
		511
		512	This function allows your callbacks to block by executing them in another
		513	coroutine where it is safe to block. One example where blocking is handy
		514	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		515	disk.
		516
		517	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		518	creating event callbacks that want to block.
		519
		520	=cut
		521
		522	our @unblock_queue;
		523
		524	# we create a special coro because we want to cede,
		525	# to reduce pressure on the coro pool (because most callbacks
		526	# return immediately and can be reused) and because we cannot cede
		527	# inside an event callback.
		528	our $unblock_scheduler = async {
		529	while () {
		530	while (my $cb = pop @unblock_queue) {
		531	# this is an inlined copy of async_pool
		532	my $coro = (pop @pool or new Coro \&pool_handler);
		533
		534	$coro->{_invoke} = $cb;
		535	$coro->ready;
		536	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		537	}
		538	schedule; # sleep well
		539	}
		540	};
		541
		542	sub unblock_sub(&) {
		543	my $cb = shift;
		544
		545	sub {
		546	unshift @unblock_queue, [$cb, @_];
		547	$unblock_scheduler->ready;
		548	}
		549	}
		550
		551	=back
		552
327	=cut	553	=cut
328		554
329	1;	555	1;
330		556
331	=head1 BUGS/LIMITATIONS	557	=head1 BUGS/LIMITATIONS

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Comparing Coro/Coro.pm (file contents): Revision 1.87 by root, Sun Nov 26 02:16:19 2006 UTC vs. Revision 1.107 by root, Fri Jan 5 18:25:51 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.87 by root, Sun Nov 26 02:16:19 2006 UTC vs.
Revision 1.107 by root, Fri Jan 5 18:25:51 2007 UTC