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

Comparing Coro/Coro.pm (file contents):
Revision 1.36 by root, Mon Sep 24 01:36:20 2001 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
26	This module is still experimental, see the BUGS section below.	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).
27		34
28	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
29	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30	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
31	important global variables.	38	variables.
32		39
33	=cut	40	=cut
34		41
35	package Coro;	42	package Coro;
36		43
		44	use strict;
37	no warnings qw(uninitialized);	45	no warnings "uninitialized";
38		46
39	use Coro::State;	47	use Coro::State;
40		48
41	use base Exporter;	49	use base qw(Coro::State Exporter);
42		50
43	$VERSION = 0.5;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
44		54
		55	our $VERSION = '3.3';
		56
45	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
46	%EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48	);	60	);
49	@EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
50		62
51	{	63	{
52	my @async;	64	my @async;
53	my $init;	65	my $init;
54		66
55	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
56	sub import {	68	sub import {
		69	no strict 'refs';
		70
57	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
58	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
61	my @attrs;	76	my @attrs;
62	for (@_) {	77	for (@_) {
…		…
77	};	92	};
78	}	93	}
79		94
80	}	95	}
81		96
		97	=over 4
		98
82	=item $main	99	=item $main
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;
		161	my $manager;
		162
121	my $manager = new Coro sub {	163	$manager = new Coro sub {
122	while() {	164	while () {
123	delete ((pop @destroy)->{_coro_state}) while @destroy;	165	(shift @destroy)->_cancel
		166	while @destroy;
		167
124	&schedule;	168	&schedule;
125	}	169	}
126	};	170	};
127		171
		172	$manager->prio (PRIO_MAX);
		173
128	# static methods. not really.	174	# static methods. not really.
129		175
		176	=back
		177
130	=head2 STATIC METHODS	178	=head2 STATIC METHODS
131		179
132	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.
133		181
134	=over 4	182	=over 4
135		183
136	=item async { ... } [@args...]	184	=item async { ... } [@args...]
137		185
138	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
139	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
140	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.
141		194
142	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
143	async {	196	async {
144	print "@_\n";	197	print "@_\n";
145	} 1,2,3,4;	198	} 1,2,3,4;
146		199
147	The coderef you submit MUST NOT be a closure that refers to variables
148	in an outer scope. This does NOT work. Pass arguments into it instead.
149
150	=cut	200	=cut
151		201
152	sub async(&@) {	202	sub async(&@) {
153	my $pid = new Coro @_;	203	my $coro = new Coro @_;
154	$manager->ready; # this ensures that the stack is cloned from the manager
155	$pid->ready;	204	$coro->ready;
156	$pid;	205	$coro
157	}	206	}
158		207
159	=item schedule	208	=item schedule
160		209
161	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
162	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
163	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
164		214
165	=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	}
166		233
167	=item cede	234	=item cede
168		235
169	"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
170	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
171	current "timeslice" to other coroutines of the same or higher priority.	238	current "timeslice" to other coroutines of the same or higher priority.
172		239
173	=cut	240	=item Coro::cede_notself
174		241
		242	Works like cede, but is not exported by default and will cede to any
		243	coroutine, regardless of priority, once.
		244
175	=item terminate	245	=item terminate [arg...]
176		246
177	Terminates the current process.	247	Terminates the current coroutine with the given status values (see L<cancel>).
178
179	Future versions of this function will allow result arguments.
180		248
181	=cut	249	=cut
182		250
183	sub terminate {	251	sub terminate {
184	$current->cancel;	252	$current->cancel (@_);
185	&schedule;
186	die; # NORETURN
187	}	253	}
188		254
189	=back	255	=back
190		256
191	# dynamic methods	257	# dynamic methods
192		258
193	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
194		260
195	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
196		262
197	=over 4	263	=over 4
198		264
199	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
200		266
201	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
202	automatically terminates. To start the process you must first put it into	268	automatically terminates as if C<terminate> with the returned values were
		269	called. To make the coroutine run you must first put it into the ready queue
203	the ready queue by calling the ready method.	270	by calling the ready method.
204		271
205	The coderef you submit MUST NOT be a closure that refers to variables	272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
206	in an outer scope. This does NOT work. Pass arguments into it instead.
207		273
208	=cut	274	=cut
209		275
210	sub _newcoro {	276	sub _run_coro {
211	terminate &{+shift};	277	terminate &{+shift};
212	}	278	}
213		279
214	sub new {	280	sub new {
215	my $class = shift;	281	my $class = shift;
216	bless {
217	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
218	}, $class;
219	}
220		282
221	=item $process->ready	283	$class->SUPER::new (\&_run_coro, @_)
		284	}
222		285
223	Put the current process into the ready queue.	286	=item $success = $coroutine->ready
224		287
225	=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.
226		291
227	=item $process->cancel	292	=item $is_ready = $coroutine->is_ready
228		293
229	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.
230		301
231	=cut	302	=cut
232		303
233	sub cancel {	304	sub cancel {
		305	my $self = shift;
		306	$self->{status} = [@_];
		307
		308	if ($current == $self) {
234	push @destroy, $_[0];	309	push @destroy, $self;
235	$manager->ready;	310	$manager->ready;
236	&schedule if $current == $_[0];	311	&schedule while 1;
		312	} else {
		313	$self->_cancel;
		314	}
237	}	315	}
238		316
		317	=item $coroutine->join
		318
		319	Wait until the coroutine terminates and return any values given to the
		320	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		321	from multiple coroutine.
		322
		323	=cut
		324
		325	sub join {
		326	my $self = shift;
		327
		328	unless ($self->{status}) {
		329	my $current = $current;
		330
		331	push @{$self->{destroy_cb}}, sub {
		332	$current->ready;
		333	undef $current;
		334	};
		335
		336	&schedule while $current;
		337	}
		338
		339	wantarray ? @{$self->{status}} : $self->{status}[0];
		340	}
		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
239	=item $oldprio = $process->prio($newprio)	356	=item $oldprio = $coroutine->prio ($newprio)
240		357
241	Sets the priority of the process. Higher priority processes get run before	358	Sets (or gets, if the argument is missing) the priority of the
242	lower priority processes. Priorities are smalled signed integer (currently	359	coroutine. Higher priority coroutines get run before lower priority
		360	coroutines. Priorities are small signed integers (currently -4 .. +3),
243	-4 .. +3), that you can refer to using PRIO_xxx constants (use the import	361	that you can refer to using PRIO_xxx constants (use the import tag :prio
244	tag :prio to get then):	362	to get then):
245		363
246	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
247	3 > 1 > 0 > -1 > -3 > -4	365	3 > 1 > 0 > -1 > -3 > -4
248		366
249	# set priority to HIGH	367	# set priority to HIGH
250	current->prio(PRIO_HIGH);	368	current->prio(PRIO_HIGH);
251		369
252	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
253	existing coroutine.	371	existing coroutine.
254		372
255	Changing the priority of the current process will take effect immediately,	373	Changing the priority of the current coroutine will take effect immediately,
256	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
257	running) will only take effect after the next schedule (of that	375	running) will only take effect after the next schedule (of that
258	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.
259		377
260	=cut
261
262	sub prio {
263	my $old = $_[0]{prio};
264	$_[0]{prio} = $_[1] if @_ > 1;
265	$old;
266	}
267
268	=item $newprio = $process->nice($change)	378	=item $newprio = $coroutine->nice ($change)
269		379
270	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.
271	higher values mean lower priority, just as in unix).	381	higher values mean lower priority, just as in unix).
272		382
273	=cut	383	=item $olddesc = $coroutine->desc ($newdesc)
274		384
275	sub nice {	385	Sets (or gets in case the argument is missing) the description for this
276	$_[0]{prio} -= $_[1];	386	coroutine. This is just a free-form string you can associate with a coroutine.
		387
		388	=cut
		389
		390	sub desc {
		391	my $old = $_[0]{desc};
		392	$_[0]{desc} = $_[1] if @_ > 1;
		393	$old;
277	}	394	}
278		395
279	=back	396	=back
280		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
281	=cut	505	=cut
282		506
283	1;	507	1;
284		508
285	=head1 BUGS/LIMITATIONS	509	=head1 BUGS/LIMITATIONS
286		510
287	- you must make very sure that no coro is still active on global destruction.	511	- you must make very sure that no coro is still active on global
288	very bad things might happen otherwise (usually segfaults).	512	destruction. very bad things might happen otherwise (usually segfaults).
		513
289	- this module is not thread-safe. You must only ever use this module from	514	- this module is not thread-safe. You should only ever use this module
290	the same thread (this requirement might be loosened in the future to	515	from the same thread (this requirement might be losened in the future
291	allow per-thread schedulers, but Coro::State does not yet allow this).	516	to allow per-thread schedulers, but Coro::State does not yet allow
		517	this).
292		518
293	=head1 SEE ALSO	519	=head1 SEE ALSO
294		520
295	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>.
296	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,	522
297	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>
298		528
299	=head1 AUTHOR	529	=head1 AUTHOR
300		530
301	Marc Lehmann <pcg@goof.com>	531	Marc Lehmann <schmorp@schmorp.de>
302	http://www.goof.com/pcg/marc/	532	http://home.schmorp.de/
303		533
304	=cut	534	=cut
305		535

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Comparing Coro/Coro.pm (file contents): Revision 1.36 by root, Mon Sep 24 01:36:20 2001 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 1.36 by root, Mon Sep 24 01:36:20 2001 UTC vs.
Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC