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

Comparing Coro/Coro.pm (file contents):
Revision 1.77 by root, Tue Oct 24 03:55:28 2006 UTC vs.
Revision 1.104 by root, Thu Jan 4 23:49:27 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
35	use strict;	44	use strict;
36	no warnings "uninitialized";	45	no warnings "uninitialized";
37		46
38	use Coro::State;	47	use Coro::State;
39		48
40	use base Exporter::;	49	use base qw(Coro::State Exporter);
41		50
42	our $idle; # idle coroutine	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 = '2.0';	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;
…		…
95		104
96	$main = new Coro;	105	$main = new Coro;
97		106
98	=item $current (or as function: current)	107	=item $current (or as function: current)
99		108
100	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
101		115
102	=cut	116	=cut
103		117
104	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
105	if ($current) {
106	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
107	}	120	if $current;
108		121
109	$current = $main;	122	_set_current $main;
110		123
111	sub current() { $current }	124	sub current() { $current }
112		125
113	=item $idle	126	=item $idle
114		127
115	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
116	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
117		131
118	=cut	132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
119		135
120	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
121	$idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
122	print STDERR "FATAL: deadlock detected\n";	138
123	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
124	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
125		157
126	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
127	# cannot destroy itself.	159	# cannot destroy itself.
128	my @destroy;	160	my @destroy;
129	my $manager;	161	my $manager;
		162
130	$manager = new Coro sub {	163	$manager = new Coro sub {
131	while () {	164	while () {
132	# by overwriting the state object with the manager we destroy it	165	(shift @destroy)->_cancel
133	# while still being able to schedule this coroutine (in case it has
134	# been readied multiple times. this is harmless since the manager
135	# can be called as many times as neccessary and will always
136	# remove itself from the runqueue
137	while (@destroy) {	166	while @destroy;
138	my $coro = pop @destroy;
139	$coro->{status} \|\|= [];
140	$_->ready for @{delete $coro->{join} \|\| []};
141		167
142	# the next line destroys the _coro_state, but keeps the
143	# process itself intact (we basically make it a zombie
144	# process that always runs the manager thread, so it's possible
145	# to transfer() to this process).
146	$coro->{_coro_state} = $manager->{_coro_state};
147	}
148	&schedule;	168	&schedule;
149	}	169	}
150	};	170	};
151		171
		172	$manager->prio (PRIO_MAX);
		173
152	# static methods. not really.	174	# static methods. not really.
153		175
154	=back	176	=back
155		177
156	=head2 STATIC METHODS	178	=head2 STATIC METHODS
157		179
158	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.
159		181
160	=over 4	182	=over 4
161		183
162	=item async { ... } [@args...]	184	=item async { ... } [@args...]
163		185
164	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
165	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
166	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
167		194
168	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
169	async {	196	async {
170	print "@_\n";	197	print "@_\n";
171	} 1,2,3,4;	198	} 1,2,3,4;
172		199
173	=cut	200	=cut
174		201
175	sub async(&@) {	202	sub async(&@) {
176	my $pid = new Coro @_;	203	my $coro = new Coro @_;
177	$manager->ready; # this ensures that the stack is cloned from the manager
178	$pid->ready;	204	$coro->ready;
179	$pid;	205	$coro
180	}	206	}
181		207
182	=item schedule	208	=item schedule
183		209
184	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
185	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
186	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
187		214
188	=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	}
189		233
190	=item cede	234	=item cede
191		235
192	"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
193	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
194	current "timeslice" to other coroutines of the same or higher priority.	238	current "timeslice" to other coroutines of the same or higher priority.
195		239
196	=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.
197		244
198	=item terminate [arg...]	245	=item terminate [arg...]
199		246
200	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>).
201		248
202	=cut	249	=cut
203		250
204	sub terminate {	251	sub terminate {
205	$current->cancel (@_);	252	$current->cancel (@_);
…		…
207		254
208	=back	255	=back
209		256
210	# dynamic methods	257	# dynamic methods
211		258
212	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
213		260
214	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
215		262
216	=over 4	263	=over 4
217		264
218	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
219		266
220	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
221	automatically terminates as if C<terminate> with the returned values were	268	automatically terminates as if C<terminate> with the returned values were
222	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
223	by calling the ready method.	270	by calling the ready method.
224		271
225	=cut	272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
226		273
		274	=cut
		275
227	sub _newcoro {	276	sub _run_coro {
228	terminate &{+shift};	277	terminate &{+shift};
229	}	278	}
230		279
231	sub new {	280	sub new {
232	my $class = shift;	281	my $class = shift;
233	bless {
234	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
235	}, $class;
236	}
237		282
238	=item $process->ready	283	$class->SUPER::new (\&_run_coro, @_)
		284	}
239		285
240	Put the given process into the ready queue.	286	=item $success = $coroutine->ready
241		287
242	=cut	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.
243		291
		292	=item $is_ready = $coroutine->is_ready
		293
		294	Return wether the coroutine is currently the ready queue or not,
		295
244	=item $process->cancel (arg...)	296	=item $coroutine->cancel (arg...)
245		297
246	Temrinates the given process and makes it return the given arguments as	298	Terminates the given coroutine and makes it return the given arguments as
247	status (default: the empty list).	299	status (default: the empty list). Never returns if the coroutine is the
		300	current coroutine.
248		301
249	=cut	302	=cut
250		303
251	sub cancel {	304	sub cancel {
252	my $self = shift;	305	my $self = shift;
253	$self->{status} = [@_];	306	$self->{status} = [@_];
		307
		308	if ($current == $self) {
254	push @destroy, $self;	309	push @destroy, $self;
255	$manager->ready;	310	$manager->ready;
256	&schedule if $current == $self;	311	&schedule while 1;
		312	} else {
		313	$self->_cancel;
		314	}
257	}	315	}
258		316
259	=item $process->join	317	=item $coroutine->join
260		318
261	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
262	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
263	from multiple processes.	321	from multiple coroutine.
264		322
265	=cut	323	=cut
266		324
267	sub join {	325	sub join {
268	my $self = shift;	326	my $self = shift;
		327
269	unless ($self->{status}) {	328	unless ($self->{status}) {
270	push @{$self->{join}}, $current;	329	my $current = $current;
271	&schedule;	330
		331	push @{$self->{destroy_cb}}, sub {
		332	$current->ready;
		333	undef $current;
		334	};
		335
		336	&schedule while $current;
272	}	337	}
		338
273	wantarray ? @{$self->{status}} : $self->{status}[0];	339	wantarray ? @{$self->{status}} : $self->{status}[0];
274	}	340	}
275		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
276	=item $oldprio = $process->prio($newprio)	356	=item $oldprio = $coroutine->prio ($newprio)
277		357
278	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
279	process. Higher priority processes get run before lower priority	359	coroutine. Higher priority coroutines get run before lower priority
280	processes. Priorities are small signed integers (currently -4 .. +3),	360	coroutines. Priorities are small signed integers (currently -4 .. +3),
281	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
282	to get then):	362	to get then):
283		363
284	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
285	3 > 1 > 0 > -1 > -3 > -4	365	3 > 1 > 0 > -1 > -3 > -4
…		…
288	current->prio(PRIO_HIGH);	368	current->prio(PRIO_HIGH);
289		369
290	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
291	existing coroutine.	371	existing coroutine.
292		372
293	Changing the priority of the current process will take effect immediately,	373	Changing the priority of the current coroutine will take effect immediately,
294	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
295	running) will only take effect after the next schedule (of that	375	running) will only take effect after the next schedule (of that
296	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.
297		377
298	=cut
299
300	sub prio {
301	my $old = $_[0]{prio};
302	$_[0]{prio} = $_[1] if @_ > 1;
303	$old;
304	}
305
306	=item $newprio = $process->nice($change)	378	=item $newprio = $coroutine->nice ($change)
307		379
308	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.
309	higher values mean lower priority, just as in unix).	381	higher values mean lower priority, just as in unix).
310		382
311	=cut
312
313	sub nice {
314	$_[0]{prio} -= $_[1];
315	}
316
317	=item $olddesc = $process->desc($newdesc)	383	=item $olddesc = $coroutine->desc ($newdesc)
318		384
319	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
320	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.
321		387
322	=cut	388	=cut
323		389
324	sub desc {	390	sub desc {
325	my $old = $_[0]{desc};	391	my $old = $_[0]{desc};
…		…
327	$old;	393	$old;
328	}	394	}
329		395
330	=back	396	=back
331		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
332	=cut	505	=cut
333		506
334	1;	507	1;
335		508
336	=head1 BUGS/LIMITATIONS	509	=head1 BUGS/LIMITATIONS

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Comparing Coro/Coro.pm (file contents): Revision 1.77 by root, Tue Oct 24 03:55:28 2006 UTC vs. Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.77 by root, Tue Oct 24 03:55:28 2006 UTC vs.
Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC