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

Comparing Coro/Coro.pm (file contents):
Revision 1.53 by root, Tue May 27 01:15:26 2003 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
		44	use strict;
35	no warnings qw(uninitialized);	45	no warnings "uninitialized";
36		46
37	use Coro::State;	47	use Coro::State;
38		48
39	use base Exporter;	49	use base qw(Coro::State Exporter);
40		50
41	$VERSION = 0.7;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
42		54
		55	our $VERSION = '3.3';
		56
43	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
44	%EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
45	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
46	);	60	);
47	@EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
48		62
49	{	63	{
50	my @async;	64	my @async;
51	my $init;	65	my $init;
52		66
53	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
54	sub import {	68	sub import {
		69	no strict 'refs';
		70
55	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
56	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
57	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
58	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
59	my @attrs;	76	my @attrs;
60	for (@_) {	77	for (@_) {
…		…
83		100
84	This coroutine represents the main program.	101	This coroutine represents the main program.
85		102
86	=cut	103	=cut
87		104
88	our $main = new Coro;	105	$main = new Coro;
89		106
90	=item $current (or as function: current)	107	=item $current (or as function: current)
91		108
92	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
93		115
94	=cut	116	=cut
95		117
96	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
97	if ($current) {
98	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
99	}	120	if $current;
100		121
101	our $current = $main;	122	_set_current $main;
102		123
103	sub current() { $current }	124	sub current() { $current }
104		125
105	=item $idle	126	=item $idle
106		127
107	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
108	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.
109		131
110	=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.
111		135
112	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
113	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
114	print STDERR "FATAL: deadlock detected\n";	138
115	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
116	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
117		157
118	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
119	# cannot destroy itself.	159	# cannot destroy itself.
120	my @destroy;	160	my @destroy;
121	my $manager;	161	my $manager;
		162
122	$manager = new Coro sub {	163	$manager = new Coro sub {
123	while() {	164	while () {
124	# by overwriting the state object with the manager we destroy it	165	(shift @destroy)->_cancel
125	# while still being able to schedule this coroutine (in case it has
126	# been readied multiple times. this is harmless since the manager
127	# can be called as many times as neccessary and will always
128	# remove itself from the runqueue
129	while (@destroy) {	166	while @destroy;
130	my $coro = pop @destroy;	167
131	$coro->{status} \|\|= [];
132	$_->ready for @{delete $coro->{join} \|\| []};
133	$coro->{_coro_state} = $manager->{_coro_state};
134	}
135	&schedule;	168	&schedule;
136	}	169	}
137	};	170	};
138		171
		172	$manager->prio (PRIO_MAX);
		173
139	# static methods. not really.	174	# static methods. not really.
140		175
141	=back	176	=back
142		177
143	=head2 STATIC METHODS	178	=head2 STATIC METHODS
144		179
145	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.
146		181
147	=over 4	182	=over 4
148		183
149	=item async { ... } [@args...]	184	=item async { ... } [@args...]
150		185
151	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
152	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
153	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.
154		194
155	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
156	async {	196	async {
157	print "@_\n";	197	print "@_\n";
158	} 1,2,3,4;	198	} 1,2,3,4;
159		199
160	The coderef you submit MUST NOT be a closure that refers to variables
161	in an outer scope. This does NOT work. Pass arguments into it instead.
162
163	=cut	200	=cut
164		201
165	sub async(&@) {	202	sub async(&@) {
166	my $pid = new Coro @_;	203	my $pid = new Coro @_;
167	$manager->ready; # this ensures that the stack is cloned from the manager
168	$pid->ready;	204	$pid->ready;
169	$pid;	205	$pid
170	}	206	}
171		207
172	=item schedule	208	=item schedule
173		209
174	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
175	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
176	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
177		214
178	=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	}
179		233
180	=item cede	234	=item cede
181		235
182	"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
183	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
184	current "timeslice" to other coroutines of the same or higher priority.	238	current "timeslice" to other coroutines of the same or higher priority.
185		239
186	=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.
187		244
188	=item terminate [arg...]	245	=item terminate [arg...]
189		246
190	Terminates the current process.	247	Terminates the current coroutine with the given status values (see L<cancel>).
191
192	Future versions of this function will allow result arguments.
193		248
194	=cut	249	=cut
195		250
196	sub terminate {	251	sub terminate {
197	$current->{status} = [@_];
198	$current->cancel;	252	$current->cancel (@_);
199	&schedule;
200	die; # NORETURN
201	}	253	}
202		254
203	=back	255	=back
204		256
205	# dynamic methods	257	# dynamic methods
206		258
207	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
208		260
209	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
210		262
211	=over 4	263	=over 4
212		264
213	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
214		266
215	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
216	automatically terminates as if C<terminate> with the returned values were	268	automatically terminates as if C<terminate> with the returned values were
217	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
218	by calling the ready method.	270	by calling the ready method.
219		271
220	=cut	272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
221		273
		274	=cut
		275
222	sub _newcoro {	276	sub _run_coro {
223	terminate &{+shift};	277	terminate &{+shift};
224	}	278	}
225		279
226	sub new {	280	sub new {
227	my $class = shift;	281	my $class = shift;
228	bless {
229	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
230	}, $class;
231	}
232		282
233	=item $process->ready	283	$class->SUPER::new (\&_run_coro, @_)
		284	}
234		285
235	Put the given process into the ready queue.	286	=item $success = $coroutine->ready
236		287
237	=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.
238		291
239	=item $process->cancel	292	=item $is_ready = $coroutine->is_ready
240		293
241	Like C<terminate>, but terminates the specified process instead.	294	Return wether the coroutine is currently the ready queue or not,
		295
		296	=item $coroutine->cancel (arg...)
		297
		298	Terminates the given coroutine and makes it return the given arguments as
		299	status (default: the empty list). Never returns if the coroutine is the
		300	current coroutine.
242		301
243	=cut	302	=cut
244		303
245	sub cancel {	304	sub cancel {
		305	my $self = shift;
		306	$self->{status} = [@_];
		307
		308	if ($current == $self) {
246	push @destroy, $_[0];	309	push @destroy, $self;
247	$manager->ready;	310	$manager->ready;
248	&schedule if $current == $_[0];	311	&schedule while 1;
		312	} else {
		313	$self->_cancel;
		314	}
249	}	315	}
250		316
251	=item $process->join	317	=item $coroutine->join
252		318
253	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
254	C<terminate> function. C<join> can be called multiple times from multiple	320	C<terminate> or C<cancel> functions. C<join> can be called multiple times
255	processes.	321	from multiple coroutine.
256		322
257	=cut	323	=cut
258		324
259	sub join {	325	sub join {
260	my $self = shift;	326	my $self = shift;
		327
261	unless ($self->{status}) {	328	unless ($self->{status}) {
262	push @{$self->{join}}, $current;	329	my $current = $current;
263	&schedule;	330
		331	push @{$self->{destroy_cb}}, sub {
		332	$current->ready;
		333	undef $current;
		334	};
		335
		336	&schedule while $current;
264	}	337	}
		338
265	wantarray ? @{$self->{status}} : $self->{status}[0];	339	wantarray ? @{$self->{status}} : $self->{status}[0];
266	}	340	}
267		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
268	=item $oldprio = $process->prio($newprio)	356	=item $oldprio = $coroutine->prio ($newprio)
269		357
270	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
271	process. Higher priority processes get run before lower priority	359	coroutine. Higher priority coroutines get run before lower priority
272	processes. Priorities are small signed integers (currently -4 .. +3),	360	coroutines. Priorities are small signed integers (currently -4 .. +3),
273	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
274	to get then):	362	to get then):
275		363
276	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
277	3 > 1 > 0 > -1 > -3 > -4	365	3 > 1 > 0 > -1 > -3 > -4
…		…
280	current->prio(PRIO_HIGH);	368	current->prio(PRIO_HIGH);
281		369
282	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
283	existing coroutine.	371	existing coroutine.
284		372
285	Changing the priority of the current process will take effect immediately,	373	Changing the priority of the current coroutine will take effect immediately,
286	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
287	running) will only take effect after the next schedule (of that	375	running) will only take effect after the next schedule (of that
288	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.
289		377
290	=cut
291
292	sub prio {
293	my $old = $_[0]{prio};
294	$_[0]{prio} = $_[1] if @_ > 1;
295	$old;
296	}
297
298	=item $newprio = $process->nice($change)	378	=item $newprio = $coroutine->nice ($change)
299		379
300	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.
301	higher values mean lower priority, just as in unix).	381	higher values mean lower priority, just as in unix).
302		382
303	=cut
304
305	sub nice {
306	$_[0]{prio} -= $_[1];
307	}
308
309	=item $olddesc = $process->desc($newdesc)	383	=item $olddesc = $coroutine->desc ($newdesc)
310		384
311	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
312	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.
313		387
314	=cut	388	=cut
315		389
316	sub desc {	390	sub desc {
317	my $old = $_[0]{desc};	391	my $old = $_[0]{desc};
…		…
319	$old;	393	$old;
320	}	394	}
321		395
322	=back	396	=back
323		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
324	=cut	505	=cut
325		506
326	1;	507	1;
327		508
328	=head1 BUGS/LIMITATIONS	509	=head1 BUGS/LIMITATIONS
…		…
335	to allow per-thread schedulers, but Coro::State does not yet allow	516	to allow per-thread schedulers, but Coro::State does not yet allow
336	this).	517	this).
337		518
338	=head1 SEE ALSO	519	=head1 SEE ALSO
339		520
340	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	521	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
341	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,	522
342	L<Coro::Handle>, L<Coro::Socket>.	523	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		524
		525	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		526
		527	Embedding: L<Coro:MakeMaker>
343		528
344	=head1 AUTHOR	529	=head1 AUTHOR
345		530
346	Marc Lehmann <pcg@goof.com>	531	Marc Lehmann <schmorp@schmorp.de>
347	http://www.goof.com/pcg/marc/	532	http://home.schmorp.de/
348		533
349	=cut	534	=cut
350		535

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Comparing Coro/Coro.pm (file contents): Revision 1.53 by root, Tue May 27 01:15:26 2003 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 1.53 by root, Tue May 27 01:15:26 2003 UTC vs.
Revision 1.103 by root, Thu Jan 4 20:14:19 2007 UTC