[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 1.103 by root, Thu Jan 4 20:14:19 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 $VERSION = '3.3';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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
…		…
189	$pid	205	$pid
190	}	206	}
191		207
192	=item schedule	208	=item schedule
193		209
194	Calls the scheduler. Please note that the current process will not be put	210	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	211	into the ready queue, so calling this function usually means you will
196	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
197		214
198	=cut	215	The canonical way to wait on external events is this:
		216
		217	{
		218	# remember current coroutine
		219	my $current = $Coro::current;
		220
		221	# register a hypothetical event handler
		222	on_event_invoke sub {
		223	# wake up sleeping coroutine
		224	$current->ready;
		225	undef $current;
		226	};
		227
		228	# call schedule until event occured.
		229	# in case we are woken up for other reasons
		230	# (current still defined), loop.
		231	Coro::schedule while $current;
		232	}
199		233
200	=item cede	234	=item cede
201		235
202	"Cede" to other processes. This function puts the current process into the	236	"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	237	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.	238	current "timeslice" to other coroutines of the same or higher priority.
205		239
206	=cut	240	=item Coro::cede_notself
		241
		242	Works like cede, but is not exported by default and will cede to any
		243	coroutine, regardless of priority, once.
207		244
208	=item terminate [arg...]	245	=item terminate [arg...]
209		246
210	Terminates the current process with the given status values (see L<cancel>).	247	Terminates the current coroutine with the given status values (see L<cancel>).
211		248
212	=cut	249	=cut
213		250
214	sub terminate {	251	sub terminate {
215	$current->cancel (@_);	252	$current->cancel (@_);
…		…
217		254
218	=back	255	=back
219		256
220	# dynamic methods	257	# dynamic methods
221		258
222	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
223		260
224	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
225		262
226	=over 4	263	=over 4
227		264
228	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
229		266
230	Create a new process and return it. When the sub returns the process	267	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	268	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	269	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	270	by calling the ready method.
234		271
235	=cut	272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
236		273
		274	=cut
		275
237	sub _new_coro {	276	sub _run_coro {
238	terminate &{+shift};	277	terminate &{+shift};
239	}	278	}
240		279
241	sub new {	280	sub new {
242	my $class = shift;	281	my $class = shift;
243		282
244	$class->SUPER::new (\&_new_coro, @_)	283	$class->SUPER::new (\&_run_coro, @_)
245	}	284	}
246		285
247	=item $process->ready	286	=item $success = $coroutine->ready
248		287
249	Put the given process into the ready queue.	288	Put the given coroutine into the ready queue (according to it's priority)
		289	and return true. If the coroutine is already in the ready queue, do nothing
		290	and return false.
250		291
251	=cut	292	=item $is_ready = $coroutine->is_ready
252		293
		294	Return wether the coroutine is currently the ready queue or not,
		295
253	=item $process->cancel (arg...)	296	=item $coroutine->cancel (arg...)
254		297
255	Terminates the given process and makes it return the given arguments as	298	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	299	status (default: the empty list). Never returns if the coroutine is the
		300	current coroutine.
257		301
258	=cut	302	=cut
259		303
260	sub cancel {	304	sub cancel {
261	my $self = shift;	305	my $self = shift;
262	$self->{status} = [@_];	306	$self->{status} = [@_];
		307
		308	if ($current == $self) {
263	push @destroy, $self;	309	push @destroy, $self;
264	$manager->ready;	310	$manager->ready;
265	&schedule if $current == $self;	311	&schedule while 1;
		312	} else {
		313	$self->_cancel;
		314	}
266	}	315	}
267		316
268	=item $process->join	317	=item $coroutine->join
269		318
270	Wait until the coroutine terminates and return any values given to the	319	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	320	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	321	from multiple coroutine.
273		322
274	=cut	323	=cut
275		324
276	sub join {	325	sub join {
277	my $self = shift;	326	my $self = shift;
		327
278	unless ($self->{status}) {	328	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	329	my $current = $current;
280	&schedule;	330
		331	push @{$self->{destroy_cb}}, sub {
		332	$current->ready;
		333	undef $current;
		334	};
		335
		336	&schedule while $current;
281	}	337	}
		338
282	wantarray ? @{$self->{status}} : $self->{status}[0];	339	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	340	}
284		341
		342	=item $coroutine->on_destroy (\&cb)
		343
		344	Registers a callback that is called when this coroutine gets destroyed,
		345	but before it is joined. The callback gets passed the terminate arguments,
		346	if any.
		347
		348	=cut
		349
		350	sub on_destroy {
		351	my ($self, $cb) = @_;
		352
		353	push @{ $self->{destroy_cb} }, $cb;
		354	}
		355
285	=item $oldprio = $process->prio ($newprio)	356	=item $oldprio = $coroutine->prio ($newprio)
286		357
287	Sets (or gets, if the argument is missing) the priority of the	358	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	359	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	360	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	361	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	362	to get then):
292		363
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	364	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	365	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	368	current->prio(PRIO_HIGH);
298		369
299	The idle coroutine ($Coro::idle) always has a lower priority than any	370	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	371	existing coroutine.
301		372
302	Changing the priority of the current process will take effect immediately,	373	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	374	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	375	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.	376	coroutine). This is a bug that will be fixed in some future version.
306		377
307	=item $newprio = $process->nice ($change)	378	=item $newprio = $coroutine->nice ($change)
308		379
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	380	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	381	higher values mean lower priority, just as in unix).
311		382
312	=item $olddesc = $process->desc ($newdesc)	383	=item $olddesc = $coroutine->desc ($newdesc)
313		384
314	Sets (or gets in case the argument is missing) the description for this	385	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.	386	coroutine. This is just a free-form string you can associate with a coroutine.
316		387
317	=cut	388	=cut
318		389
319	sub desc {	390	sub desc {
320	my $old = $_[0]{desc};	391	my $old = $_[0]{desc};
…		…
322	$old;	393	$old;
323	}	394	}
324		395
325	=back	396	=back
326		397
		398	=head2 GLOBAL FUNCTIONS
		399
		400	=over 4
		401
		402	=item Coro::nready
		403
		404	Returns the number of coroutines that are currently in the ready state,
		405	i.e. that can be swicthed to. The value C<0> means that the only runnable
		406	coroutine is the currently running one, so C<cede> would have no effect,
		407	and C<schedule> would cause a deadlock unless there is an idle handler
		408	that wakes up some coroutines.
		409
		410	=item my $guard = Coro::guard { ... }
		411
		412	This creates and returns a guard object. Nothing happens until the objetc
		413	gets destroyed, in which case the codeblock given as argument will be
		414	executed. This is useful to free locks or other resources in case of a
		415	runtime error or when the coroutine gets canceled, as in both cases the
		416	guard block will be executed. The guard object supports only one method,
		417	C<< ->cancel >>, which will keep the codeblock from being executed.
		418
		419	Example: set some flag and clear it again when the coroutine gets canceled
		420	or the function returns:
		421
		422	sub do_something {
		423	my $guard = Coro::guard { $busy = 0 };
		424	$busy = 1;
		425
		426	# do something that requires $busy to be true
		427	}
		428
		429	=cut
		430
		431	sub guard(&) {
		432	bless \(my $cb = $_[0]), "Coro::guard"
		433	}
		434
		435	sub Coro::guard::cancel {
		436	${$_[0]} = sub { };
		437	}
		438
		439	sub Coro::guard::DESTROY {
		440	${$_[0]}->();
		441	}
		442
		443
		444	=item unblock_sub { ... }
		445
		446	This utility function takes a BLOCK or code reference and "unblocks" it,
		447	returning the new coderef. This means that the new coderef will return
		448	immediately without blocking, returning nothing, while the original code
		449	ref will be called (with parameters) from within its own coroutine.
		450
		451	The reason this fucntion exists is that many event libraries (such as the
		452	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		453	of thread-safety). This means you must not block within event callbacks,
		454	otherwise you might suffer from crashes or worse.
		455
		456	This function allows your callbacks to block by executing them in another
		457	coroutine where it is safe to block. One example where blocking is handy
		458	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		459	disk.
		460
		461	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		462	creating event callbacks that want to block.
		463
		464	=cut
		465
		466	our @unblock_pool;
		467	our @unblock_queue;
		468	our $UNBLOCK_POOL_SIZE = 2;
		469
		470	sub unblock_handler_ {
		471	while () {
		472	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		473	$cb->(@arg);
		474
		475	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		476	push @unblock_pool, $Coro::current;
		477	schedule;
		478	}
		479	}
		480
		481	our $unblock_scheduler = async {
		482	while () {
		483	while (my $cb = pop @unblock_queue) {
		484	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		485	$handler->{arg} = $cb;
		486	$handler->ready;
		487	cede;
		488	}
		489
		490	schedule;
		491	}
		492	};
		493
		494	sub unblock_sub(&) {
		495	my $cb = shift;
		496
		497	sub {
		498	push @unblock_queue, [$cb, @_];
		499	$unblock_scheduler->ready;
		500	}
		501	}
		502
		503	=back
		504
327	=cut	505	=cut
328		506
329	1;	507	1;
330		508
331	=head1 BUGS/LIMITATIONS	509	=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 1.103 by root, Thu Jan 4 20:14:19 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 1.103 by root, Thu Jan 4 20:14:19 2007 UTC