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

Comparing Coro/Coro.pm (file contents):
Revision 1.30 by root, Sat Aug 11 19:59:19 2001 UTC vs.
Revision 1.119 by root, Wed Mar 28 14:24:17 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;
		45	no warnings "uninitialized";
		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 = 0.45;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
42		54
		55	our $VERSION = '3.55';
		56
43	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
44	@EXPORT_OK = qw($current);	58	our %EXPORT_TAGS = (
		59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		60	);
		61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
45		62
46	{	63	{
47	my @async;	64	my @async;
48	my $init;	65	my $init;
49		66
50	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
51	sub import {	68	sub import {
		69	no strict 'refs';
		70
52	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
53	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
54	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
55	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
56	my @attrs;	76	my @attrs;
57	for (@_) {	77	for (@_) {
…		…
72	};	92	};
73	}	93	}
74		94
75	}	95	}
76		96
		97	=over 4
		98
77	=item $main	99	=item $main
78		100
79	This coroutine represents the main program.	101	This coroutine represents the main program.
80		102
81	=cut	103	=cut
82		104
83	our $main = new Coro;	105	$main = new Coro;
84		106
85	=item $current (or as function: current)	107	=item $current (or as function: current)
86		108
87	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
88		115
89	=cut	116	=cut
90		117
91	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
92	if ($current) {
93	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
94	}	120	if $current;
95		121
96	our $current = $main;	122	_set_current $main;
97		123
98	sub current() { $current }	124	sub current() { $current }
99		125
100	=item $idle	126	=item $idle
101		127
102	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
103	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.
104		131
105	=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.
106		135
107	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
108	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
109	print STDERR "FATAL: deadlock detected\n";	138
110	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
111	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
112		157
113	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
114	# cannot destroy itself.	159	# cannot destroy itself.
115	my @destroy;	160	my @destroy;
		161	my $manager;
		162
116	my $manager = new Coro sub {	163	$manager = new Coro sub {
117	while() {	164	while () {
118	delete ((pop @destroy)->{_coro_state}) while @destroy;	165	(shift @destroy)->_cancel
		166	while @destroy;
		167
119	&schedule;	168	&schedule;
120	}	169	}
121	};	170	};
122		171
		172	$manager->prio (PRIO_MAX);
		173
123	# static methods. not really.	174	# static methods. not really.
124		175
		176	=back
		177
125	=head2 STATIC METHODS	178	=head2 STATIC METHODS
126		179
127	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.
128		181
129	=over 4	182	=over 4
130		183
131	=item async { ... } [@args...]	184	=item async { ... } [@args...]
132		185
133	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
134	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
135	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.
136		194
137	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
138	async {	196	async {
139	print "@_\n";	197	print "@_\n";
140	} 1,2,3,4;	198	} 1,2,3,4;
141		199
142	The coderef you submit MUST NOT be a closure that refers to variables
143	in an outer scope. This does NOT work. Pass arguments into it instead.
144
145	=cut	200	=cut
146		201
147	sub async(&@) {	202	sub async(&@) {
148	my $pid = new Coro @_;	203	my $coro = new Coro @_;
149	$manager->ready; # this ensures that the stack is cloned from the manager
150	$pid->ready;	204	$coro->ready;
151	$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
		216	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		217	will not work in the expected way, unless you call terminate or cancel,
		218	which somehow defeats the purpose of pooling.
		219
		220	The priority will be reset to C<0> after each job, otherwise the coroutine
		221	will be re-used "as-is".
		222
		223	The pool size is limited to 8 idle coroutines (this can be adjusted by
		224	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		225	required.
		226
		227	If you are concerned about pooled coroutines growing a lot because a
		228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		229	terminate }> once per second or so to slowly replenish the pool.
		230
		231	=cut
		232
		233	our $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	eval {
		239	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		240	$cb->(@arg);
		241	};
		242	warn $@ if $@;
		243
		244	last if @pool >= $POOL_SIZE;
		245	push @pool, $current;
		246
		247	$current->save (Coro::State::SAVE_DEF);
		248	$current->prio (0);
		249	schedule;
		250	}
		251	}
		252
		253	sub async_pool(&@) {
		254	# this is also inlined into the unlock_scheduler
		255	my $coro = (pop @pool or new Coro \&pool_handler);
		256
		257	$coro->{_invoke} = [@_];
		258	$coro->ready;
		259
		260	$coro
152	}	261	}
153		262
154	=item schedule	263	=item schedule
155		264
156	Calls the scheduler. Please note that the current process will not be put	265	Calls the scheduler. Please note that the current coroutine will not be put
157	into the ready queue, so calling this function usually means you will	266	into the ready queue, so calling this function usually means you will
158	never be called again.	267	never be called again unless something else (e.g. an event handler) calls
		268	ready.
159		269
160	=cut	270	The canonical way to wait on external events is this:
		271
		272	{
		273	# remember current coroutine
		274	my $current = $Coro::current;
		275
		276	# register a hypothetical event handler
		277	on_event_invoke sub {
		278	# wake up sleeping coroutine
		279	$current->ready;
		280	undef $current;
		281	};
		282
		283	# call schedule until event occured.
		284	# in case we are woken up for other reasons
		285	# (current still defined), loop.
		286	Coro::schedule while $current;
		287	}
161		288
162	=item cede	289	=item cede
163		290
164	"Cede" to other processes. This function puts the current process into the	291	"Cede" to other coroutines. This function puts the current coroutine into the
165	ready queue and calls C<schedule>, which has the effect of giving up the	292	ready queue and calls C<schedule>, which has the effect of giving up the
166	current "timeslice" to other coroutines of the same or higher priority.	293	current "timeslice" to other coroutines of the same or higher priority.
167		294
168	=cut	295	Returns true if at least one coroutine switch has happened.
169		296
		297	=item Coro::cede_notself
		298
		299	Works like cede, but is not exported by default and will cede to any
		300	coroutine, regardless of priority, once.
		301
		302	Returns true if at least one coroutine switch has happened.
		303
170	=item terminate	304	=item terminate [arg...]
171		305
172	Terminates the current process.	306	Terminates the current coroutine with the given status values (see L<cancel>).
173
174	Future versions of this function will allow result arguments.
175		307
176	=cut	308	=cut
177		309
178	sub terminate {	310	sub terminate {
179	$current->cancel;	311	$current->cancel (@_);
180	&schedule;
181	die; # NORETURN
182	}	312	}
183		313
184	=back	314	=back
185		315
186	# dynamic methods	316	# dynamic methods
187		317
188	=head2 PROCESS METHODS	318	=head2 COROUTINE METHODS
189		319
190	These are the methods you can call on process objects.	320	These are the methods you can call on coroutine objects.
191		321
192	=over 4	322	=over 4
193		323
194	=item new Coro \&sub [, @args...]	324	=item new Coro \&sub [, @args...]
195		325
196	Create a new process and return it. When the sub returns the process	326	Create a new coroutine and return it. When the sub returns the coroutine
197	automatically terminates. To start the process you must first put it into	327	automatically terminates as if C<terminate> with the returned values were
		328	called. To make the coroutine run you must first put it into the ready queue
198	the ready queue by calling the ready method.	329	by calling the ready method.
199		330
200	The coderef you submit MUST NOT be a closure that refers to variables	331	Calling C<exit> in a coroutine will not work correctly, so do not do that.
201	in an outer scope. This does NOT work. Pass arguments into it instead.
202		332
203	=cut	333	=cut
204		334
205	sub _newcoro {	335	sub _run_coro {
206	terminate &{+shift};	336	terminate &{+shift};
207	}	337	}
208		338
209	sub new {	339	sub new {
210	my $class = shift;	340	my $class = shift;
211	bless {
212	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
213	}, $class;
214	}
215		341
216	=item $process->ready	342	$class->SUPER::new (\&_run_coro, @_)
		343	}
217		344
218	Put the current process into the ready queue.	345	=item $success = $coroutine->ready
219		346
220	=cut	347	Put the given coroutine into the ready queue (according to it's priority)
		348	and return true. If the coroutine is already in the ready queue, do nothing
		349	and return false.
221		350
222	=item $process->cancel	351	=item $is_ready = $coroutine->is_ready
223		352
224	Like C<terminate>, but terminates the specified process instead.	353	Return wether the coroutine is currently the ready queue or not,
		354
		355	=item $coroutine->cancel (arg...)
		356
		357	Terminates the given coroutine and makes it return the given arguments as
		358	status (default: the empty list). Never returns if the coroutine is the
		359	current coroutine.
225		360
226	=cut	361	=cut
227		362
228	sub cancel {	363	sub cancel {
		364	my $self = shift;
		365	$self->{status} = [@_];
		366
		367	if ($current == $self) {
229	push @destroy, $_[0];	368	push @destroy, $self;
230	$manager->ready;	369	$manager->ready;
		370	&schedule while 1;
		371	} else {
		372	$self->_cancel;
		373	}
		374	}
		375
		376	=item $coroutine->join
		377
		378	Wait until the coroutine terminates and return any values given to the
		379	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		380	from multiple coroutine.
		381
		382	=cut
		383
		384	sub join {
		385	my $self = shift;
		386
		387	unless ($self->{status}) {
		388	my $current = $current;
		389
		390	push @{$self->{destroy_cb}}, sub {
		391	$current->ready;
		392	undef $current;
		393	};
		394
		395	&schedule while $current;
		396	}
		397
		398	wantarray ? @{$self->{status}} : $self->{status}[0];
		399	}
		400
		401	=item $coroutine->on_destroy (\&cb)
		402
		403	Registers a callback that is called when this coroutine gets destroyed,
		404	but before it is joined. The callback gets passed the terminate arguments,
		405	if any.
		406
		407	=cut
		408
		409	sub on_destroy {
		410	my ($self, $cb) = @_;
		411
		412	push @{ $self->{destroy_cb} }, $cb;
		413	}
		414
		415	=item $oldprio = $coroutine->prio ($newprio)
		416
		417	Sets (or gets, if the argument is missing) the priority of the
		418	coroutine. Higher priority coroutines get run before lower priority
		419	coroutines. Priorities are small signed integers (currently -4 .. +3),
		420	that you can refer to using PRIO_xxx constants (use the import tag :prio
		421	to get then):
		422
		423	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		424	3 > 1 > 0 > -1 > -3 > -4
		425
		426	# set priority to HIGH
		427	current->prio(PRIO_HIGH);
		428
		429	The idle coroutine ($Coro::idle) always has a lower priority than any
		430	existing coroutine.
		431
		432	Changing the priority of the current coroutine will take effect immediately,
		433	but changing the priority of coroutines in the ready queue (but not
		434	running) will only take effect after the next schedule (of that
		435	coroutine). This is a bug that will be fixed in some future version.
		436
		437	=item $newprio = $coroutine->nice ($change)
		438
		439	Similar to C<prio>, but subtract the given value from the priority (i.e.
		440	higher values mean lower priority, just as in unix).
		441
		442	=item $olddesc = $coroutine->desc ($newdesc)
		443
		444	Sets (or gets in case the argument is missing) the description for this
		445	coroutine. This is just a free-form string you can associate with a coroutine.
		446
		447	=cut
		448
		449	sub desc {
		450	my $old = $_[0]{desc};
		451	$_[0]{desc} = $_[1] if @_ > 1;
		452	$old;
231	}	453	}
232		454
233	=back	455	=back
234		456
		457	=head2 GLOBAL FUNCTIONS
		458
		459	=over 4
		460
		461	=item Coro::nready
		462
		463	Returns the number of coroutines that are currently in the ready state,
		464	i.e. that can be swicthed to. The value C<0> means that the only runnable
		465	coroutine is the currently running one, so C<cede> would have no effect,
		466	and C<schedule> would cause a deadlock unless there is an idle handler
		467	that wakes up some coroutines.
		468
		469	=item my $guard = Coro::guard { ... }
		470
		471	This creates and returns a guard object. Nothing happens until the object
		472	gets destroyed, in which case the codeblock given as argument will be
		473	executed. This is useful to free locks or other resources in case of a
		474	runtime error or when the coroutine gets canceled, as in both cases the
		475	guard block will be executed. The guard object supports only one method,
		476	C<< ->cancel >>, which will keep the codeblock from being executed.
		477
		478	Example: set some flag and clear it again when the coroutine gets canceled
		479	or the function returns:
		480
		481	sub do_something {
		482	my $guard = Coro::guard { $busy = 0 };
		483	$busy = 1;
		484
		485	# do something that requires $busy to be true
		486	}
		487
		488	=cut
		489
		490	sub guard(&) {
		491	bless \(my $cb = $_[0]), "Coro::guard"
		492	}
		493
		494	sub Coro::guard::cancel {
		495	${$_[0]} = sub { };
		496	}
		497
		498	sub Coro::guard::DESTROY {
		499	${$_[0]}->();
		500	}
		501
		502
		503	=item unblock_sub { ... }
		504
		505	This utility function takes a BLOCK or code reference and "unblocks" it,
		506	returning the new coderef. This means that the new coderef will return
		507	immediately without blocking, returning nothing, while the original code
		508	ref will be called (with parameters) from within its own coroutine.
		509
		510	The reason this fucntion exists is that many event libraries (such as the
		511	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		512	of thread-safety). This means you must not block within event callbacks,
		513	otherwise you might suffer from crashes or worse.
		514
		515	This function allows your callbacks to block by executing them in another
		516	coroutine where it is safe to block. One example where blocking is handy
		517	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		518	disk.
		519
		520	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		521	creating event callbacks that want to block.
		522
		523	=cut
		524
		525	our @unblock_queue;
		526
		527	# we create a special coro because we want to cede,
		528	# to reduce pressure on the coro pool (because most callbacks
		529	# return immediately and can be reused) and because we cannot cede
		530	# inside an event callback.
		531	our $unblock_scheduler = async {
		532	while () {
		533	while (my $cb = pop @unblock_queue) {
		534	# this is an inlined copy of async_pool
		535	my $coro = (pop @pool or new Coro \&pool_handler);
		536
		537	$coro->{_invoke} = $cb;
		538	$coro->ready;
		539	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		540	}
		541	schedule; # sleep well
		542	}
		543	};
		544
		545	sub unblock_sub(&) {
		546	my $cb = shift;
		547
		548	sub {
		549	unshift @unblock_queue, [$cb, @_];
		550	$unblock_scheduler->ready;
		551	}
		552	}
		553
		554	=back
		555
235	=cut	556	=cut
236		557
237	1;	558	1;
238		559
239	=head1 BUGS/LIMITATIONS	560	=head1 BUGS/LIMITATIONS
240		561
241	- could be faster, especially when the core would introduce special	562	- you must make very sure that no coro is still active on global
242	support for coroutines (like it does for threads).	563	destruction. very bad things might happen otherwise (usually segfaults).
243	- there is still a memleak on coroutine termination that I could not	564
244	identify. Could be as small as a single SV.
245	- this module is not well-tested.
246	- if variables or arguments "disappear" (become undef) or become
247	corrupted please contact the author so he cen iron out the
248	remaining bugs.
249	- this module is not thread-safe. You must only ever use this module from	565	- this module is not thread-safe. You should only ever use this module
250	the same thread (this requirement might be loosened in the future to	566	from the same thread (this requirement might be losened in the future
251	allow per-thread schedulers, but Coro::State does not yet allow this).	567	to allow per-thread schedulers, but Coro::State does not yet allow
		568	this).
252		569
253	=head1 SEE ALSO	570	=head1 SEE ALSO
254		571
255	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	572	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
256	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,	573
257	L<Coro::Handle>, L<Coro::Socket>.	574	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		575
		576	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		577
		578	Embedding: L<Coro:MakeMaker>
258		579
259	=head1 AUTHOR	580	=head1 AUTHOR
260		581
261	Marc Lehmann <pcg@goof.com>	582	Marc Lehmann <schmorp@schmorp.de>
262	http://www.goof.com/pcg/marc/	583	http://home.schmorp.de/
263		584
264	=cut	585	=cut
265		586

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Comparing Coro/Coro.pm (file contents): Revision 1.30 by root, Sat Aug 11 19:59:19 2001 UTC vs. Revision 1.119 by root, Wed Mar 28 14:24:17 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.30 by root, Sat Aug 11 19:59:19 2001 UTC vs.
Revision 1.119 by root, Wed Mar 28 14:24:17 2007 UTC