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

Comparing Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.105 by root, Fri Jan 5 16:55:01 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	yield;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
		23	This module collection manages coroutines. Coroutines are similar
		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.
		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
		35	In this module, coroutines are defined as "callchain + lexical variables +
		36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
		37	its own set of lexicals and its own set of perls most important global
		38	variables.
		39
23	=cut	40	=cut
24		41
25	package Coro;	42	package Coro;
26		43
		44	use strict;
		45	no warnings "uninitialized";
		46
27	use Coro::State;	47	use Coro::State;
28		48
29	use base Exporter;	49	use base qw(Coro::State Exporter);
30		50
		51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
		54
31	$VERSION = 0.03;	55	our $VERSION = '3.3';
32		56
33	@EXPORT = qw(async yield schedule);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
34	@EXPORT_OK = qw($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));
35		62
36	{	63	{
37	use subs 'async';
38
39	my @async;	64	my @async;
		65	my $init;
40		66
41	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
42	sub import {	68	sub import {
		69	no strict 'refs';
		70
43	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
44	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
45	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
46	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
47	my @attrs;	76	my @attrs;
48	for (@_) {	77	for (@_) {
49	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
50	push @async, $ref;	79	push @async, $ref;
		80	unless ($init++) {
		81	eval q{
		82	sub INIT {
		83	&async(pop @async) while @async;
		84	}
		85	};
		86	}
51	} else {	87	} else {
52	push @attrs, @_;	88	push @attrs, $_;
53	}	89	}
54	}	90	}
55	return $old ? $old->($package, $name, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
56	};	92	};
57	}	93	}
58		94
59	sub INIT {
60	async pop @async while @async;
61	}
62	}	95	}
63		96
64	my $idle = new Coro sub {	97	=over 4
65	&yield while 1;	98
		99	=item $main
		100
		101	This coroutine represents the main program.
		102
		103	=cut
		104
		105	$main = new Coro;
		106
		107	=item $current (or as function: current)
		108
		109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$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.
		115
		116	=cut
		117
		118	# maybe some other module used Coro::Specific before...
		119	$main->{specific} = $current->{specific}
		120	if $current;
		121
		122	_set_current $main;
		123
		124	sub current() { $current }
		125
		126	=item $idle
		127
		128	A callback that is called whenever the scheduler finds no ready coroutines
		129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
		131
		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.
		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.
		138
		139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
66	};	144	};
67		145
68	=item $main	146	sub _cancel {
		147	my ($self) = @_;
69		148
70	This coroutine represents the main program.	149	# free coroutine data and mark as destructed
		150	$self->_destroy
		151	or return;
71		152
72	=cut	153	# call all destruction callbacks
73		154	$_->(@{$self->{status}})
74	$main = new Coro;	155	for @{(delete $self->{destroy_cb}) \|\| []};
75
76	=item $current
77
78	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
79
80	=cut
81
82	# maybe some other module used Coro::Specific before...
83	if ($current) {
84	$main->{specific} = $current->{specific};
85	}	156	}
86		157
87	$current = $main;	158	# this coroutine is necessary because a coroutine
		159	# cannot destroy itself.
		160	my @destroy;
		161	my $manager;
88		162
89	# we really need priorities...	163	$manager = new Coro sub {
90	my @ready = (); # the ready queue. hehe, rather broken ;)	164	while () {
		165	(shift @destroy)->_cancel
		166	while @destroy;
		167
		168	&schedule;
		169	}
		170	};
		171
		172	$manager->prio (PRIO_MAX);
91		173
92	# static methods. not really.	174	# static methods. not really.
93		175
		176	=back
		177
94	=head2 STATIC METHODS	178	=head2 STATIC METHODS
95		179
96	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.
97		181
98	=over 4	182	=over 4
99		183
100	=item async { ... };	184	=item async { ... } [@args...]
101		185
102	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	188	terminated.
105		189
106	=cut	190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
107		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
		194
		195	# create a new coroutine that just prints its arguments
		196	async {
		197	print "@_\n";
		198	} 1,2,3,4;
		199
		200	=cut
		201
108	sub async(&) {	202	sub async(&@) {
109	(new Coro $_[0])->ready;	203	my $coro = new Coro @_;
		204	$coro->ready;
		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 C<async> does.
		216
		217	The priority will be reset to C<0> after each job, otherwise the coroutine
		218	will be re-used "as-is".
		219
		220	The pool size is limited to 8 idle coroutines (this can be adjusted by
		221	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		222	required.
		223
		224	If you are concerned about pooled coroutines growing a lot because a
		225	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		226	terminate }> once per second or so to slowly replenish the pool.
		227
		228	=cut
		229
		230	our $POOL_SIZE = 8;
		231	our @pool;
		232
		233	sub pool_handler {
		234	while () {
		235	my ($cb, @arg) = @{ delete $current->{_invoke} };
		236
		237	eval {
		238	$cb->(@arg);
		239	};
		240	warn $@ if $@;
		241
		242	last if @pool >= $POOL_SIZE;
		243	push @pool, $current;
		244
		245	$current->prio (0);
		246	schedule;
		247	}
		248	}
		249
		250	sub async_pool(&@) {
		251	# this is also inlined into the unlock_scheduler
		252	my $coro = (pop @pool or new Coro \&pool_handler);
		253
		254	$coro->{_invoke} = [@_];
		255	$coro->ready;
		256
		257	$coro
110	}	258	}
111		259
112	=item schedule	260	=item schedule
113		261
114	Calls the scheduler. Please note that the current process will not be put	262	Calls the scheduler. Please note that the current coroutine will not be put
115	into the ready queue, so calling this function usually means you will	263	into the ready queue, so calling this function usually means you will
116	never be called again.	264	never be called again unless something else (e.g. an event handler) calls
		265	ready.
117		266
118	=cut	267	The canonical way to wait on external events is this:
119		268
120	my $prev;	269	{
		270	# remember current coroutine
		271	my $current = $Coro::current;
121		272
122	sub schedule {	273	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	274	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	275	# wake up sleeping coroutine
125	}
126
127	=item yield
128
129	Yield to other processes. This function puts the current process into the
130	ready queue and calls C<schedule>.
131
132	=cut
133
134	sub yield {
135	$current->ready;	276	$current->ready;
136	&schedule;	277	undef $current;
137	}	278	};
138		279
		280	# call schedule until event occured.
		281	# in case we are woken up for other reasons
		282	# (current still defined), loop.
		283	Coro::schedule while $current;
		284	}
		285
		286	=item cede
		287
		288	"Cede" to other coroutines. This function puts the current coroutine into the
		289	ready queue and calls C<schedule>, which has the effect of giving up the
		290	current "timeslice" to other coroutines of the same or higher priority.
		291
		292	=item Coro::cede_notself
		293
		294	Works like cede, but is not exported by default and will cede to any
		295	coroutine, regardless of priority, once.
		296
139	=item terminate	297	=item terminate [arg...]
140		298
141	Terminates the current process.	299	Terminates the current coroutine with the given status values (see L<cancel>).
142		300
143	=cut	301	=cut
144		302
145	sub terminate {	303	sub terminate {
146	&schedule;	304	$current->cancel (@_);
147	}	305	}
148		306
149	=back	307	=back
150		308
151	# dynamic methods	309	# dynamic methods
152		310
153	=head2 PROCESS METHODS	311	=head2 COROUTINE METHODS
154		312
155	These are the methods you can call on process objects.	313	These are the methods you can call on coroutine objects.
156		314
157	=over 4	315	=over 4
158		316
159	=item new Coro \⊂	317	=item new Coro \&sub [, @args...]
160		318
161	Create a new process and return it. When the sub returns the process	319	Create a new coroutine and return it. When the sub returns the coroutine
162	automatically terminates. To start the process you must first put it into	320	automatically terminates as if C<terminate> with the returned values were
		321	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	322	by calling the ready method.
164		323
		324	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		325
165	=cut	326	=cut
		327
		328	sub _run_coro {
		329	terminate &{+shift};
		330	}
166		331
167	sub new {	332	sub new {
168	my $class = shift;	333	my $class = shift;
		334
		335	$class->SUPER::new (\&_run_coro, @_)
		336	}
		337
		338	=item $success = $coroutine->ready
		339
		340	Put the given coroutine into the ready queue (according to it's priority)
		341	and return true. If the coroutine is already in the ready queue, do nothing
		342	and return false.
		343
		344	=item $is_ready = $coroutine->is_ready
		345
		346	Return wether the coroutine is currently the ready queue or not,
		347
		348	=item $coroutine->cancel (arg...)
		349
		350	Terminates the given coroutine and makes it return the given arguments as
		351	status (default: the empty list). Never returns if the coroutine is the
		352	current coroutine.
		353
		354	=cut
		355
		356	sub cancel {
		357	my $self = shift;
		358	$self->{status} = [@_];
		359
		360	if ($current == $self) {
		361	push @destroy, $self;
		362	$manager->ready;
		363	&schedule while 1;
		364	} else {
		365	$self->_cancel;
		366	}
		367	}
		368
		369	=item $coroutine->join
		370
		371	Wait until the coroutine terminates and return any values given to the
		372	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		373	from multiple coroutine.
		374
		375	=cut
		376
		377	sub join {
		378	my $self = shift;
		379
		380	unless ($self->{status}) {
		381	my $current = $current;
		382
		383	push @{$self->{destroy_cb}}, sub {
		384	$current->ready;
		385	undef $current;
		386	};
		387
		388	&schedule while $current;
		389	}
		390
		391	wantarray ? @{$self->{status}} : $self->{status}[0];
		392	}
		393
		394	=item $coroutine->on_destroy (\&cb)
		395
		396	Registers a callback that is called when this coroutine gets destroyed,
		397	but before it is joined. The callback gets passed the terminate arguments,
		398	if any.
		399
		400	=cut
		401
		402	sub on_destroy {
		403	my ($self, $cb) = @_;
		404
		405	push @{ $self->{destroy_cb} }, $cb;
		406	}
		407
		408	=item $oldprio = $coroutine->prio ($newprio)
		409
		410	Sets (or gets, if the argument is missing) the priority of the
		411	coroutine. Higher priority coroutines get run before lower priority
		412	coroutines. Priorities are small signed integers (currently -4 .. +3),
		413	that you can refer to using PRIO_xxx constants (use the import tag :prio
		414	to get then):
		415
		416	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		417	3 > 1 > 0 > -1 > -3 > -4
		418
		419	# set priority to HIGH
		420	current->prio(PRIO_HIGH);
		421
		422	The idle coroutine ($Coro::idle) always has a lower priority than any
		423	existing coroutine.
		424
		425	Changing the priority of the current coroutine will take effect immediately,
		426	but changing the priority of coroutines in the ready queue (but not
		427	running) will only take effect after the next schedule (of that
		428	coroutine). This is a bug that will be fixed in some future version.
		429
		430	=item $newprio = $coroutine->nice ($change)
		431
		432	Similar to C<prio>, but subtract the given value from the priority (i.e.
		433	higher values mean lower priority, just as in unix).
		434
		435	=item $olddesc = $coroutine->desc ($newdesc)
		436
		437	Sets (or gets in case the argument is missing) the description for this
		438	coroutine. This is just a free-form string you can associate with a coroutine.
		439
		440	=cut
		441
		442	sub desc {
169	my $proc = $_[0];	443	my $old = $_[0]{desc};
170	bless {	444	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	445	$old;
172	}, $class;
173	}
174
175	=item $process->ready
176
177	Put the current process into the ready queue.
178
179	=cut
180
181	sub ready {
182	push @ready, $_[0];
183	}	446	}
184		447
185	=back	448	=back
186		449
		450	=head2 GLOBAL FUNCTIONS
		451
		452	=over 4
		453
		454	=item Coro::nready
		455
		456	Returns the number of coroutines that are currently in the ready state,
		457	i.e. that can be swicthed to. The value C<0> means that the only runnable
		458	coroutine is the currently running one, so C<cede> would have no effect,
		459	and C<schedule> would cause a deadlock unless there is an idle handler
		460	that wakes up some coroutines.
		461
		462	=item my $guard = Coro::guard { ... }
		463
		464	This creates and returns a guard object. Nothing happens until the objetc
		465	gets destroyed, in which case the codeblock given as argument will be
		466	executed. This is useful to free locks or other resources in case of a
		467	runtime error or when the coroutine gets canceled, as in both cases the
		468	guard block will be executed. The guard object supports only one method,
		469	C<< ->cancel >>, which will keep the codeblock from being executed.
		470
		471	Example: set some flag and clear it again when the coroutine gets canceled
		472	or the function returns:
		473
		474	sub do_something {
		475	my $guard = Coro::guard { $busy = 0 };
		476	$busy = 1;
		477
		478	# do something that requires $busy to be true
		479	}
		480
		481	=cut
		482
		483	sub guard(&) {
		484	bless \(my $cb = $_[0]), "Coro::guard"
		485	}
		486
		487	sub Coro::guard::cancel {
		488	${$_[0]} = sub { };
		489	}
		490
		491	sub Coro::guard::DESTROY {
		492	${$_[0]}->();
		493	}
		494
		495
		496	=item unblock_sub { ... }
		497
		498	This utility function takes a BLOCK or code reference and "unblocks" it,
		499	returning the new coderef. This means that the new coderef will return
		500	immediately without blocking, returning nothing, while the original code
		501	ref will be called (with parameters) from within its own coroutine.
		502
		503	The reason this fucntion exists is that many event libraries (such as the
		504	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		505	of thread-safety). This means you must not block within event callbacks,
		506	otherwise you might suffer from crashes or worse.
		507
		508	This function allows your callbacks to block by executing them in another
		509	coroutine where it is safe to block. One example where blocking is handy
		510	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		511	disk.
		512
		513	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		514	creating event callbacks that want to block.
		515
		516	=cut
		517
		518	our @unblock_queue;
		519
		520	# we create a special coro because we want to cede,
		521	# to reduce pressure on the coro pool (because most callbacks
		522	# return immediately and can be reused) and because we cannot cede
		523	# inside an event callback.
		524	our $unblock_scheduler = async {
		525	while () {
		526	while (my $cb = pop @unblock_queue) {
		527	# this is an inlined copy of async_pool
		528	my $coro = (pop @pool or new Coro \&pool_handler);
		529
		530	$coro->{_invoke} = $cb;
		531	$coro->ready;
		532	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		533	}
		534	schedule; # sleep well
		535	}
		536	};
		537
		538	sub unblock_sub(&) {
		539	my $cb = shift;
		540
		541	sub {
		542	unshift @unblock_queue, [$cb, @_];
		543	$unblock_scheduler->ready;
		544	}
		545	}
		546
		547	=back
		548
187	=cut	549	=cut
188		550
189	1;	551	1;
190		552
		553	=head1 BUGS/LIMITATIONS
		554
		555	- you must make very sure that no coro is still active on global
		556	destruction. very bad things might happen otherwise (usually segfaults).
		557
		558	- this module is not thread-safe. You should only ever use this module
		559	from the same thread (this requirement might be losened in the future
		560	to allow per-thread schedulers, but Coro::State does not yet allow
		561	this).
		562
		563	=head1 SEE ALSO
		564
		565	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		566
		567	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		568
		569	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		570
		571	Embedding: L<Coro:MakeMaker>
		572
191	=head1 AUTHOR	573	=head1 AUTHOR
192		574
193	Marc Lehmann <pcg@goof.com>	575	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	576	http://home.schmorp.de/
195		577
196	=cut	578	=cut
197		579

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Comparing Coro/Coro.pm (file contents): Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs. Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC