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

Comparing Coro/Coro.pm (file contents):
Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs.
Revision 1.97 by root, Mon Dec 4 13:47:56 2006 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - create and manage coroutines	3	Coro - coroutine process abstraction
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	$new = new Coro sub {	9	async {
10	print "in coroutine, switching back\n";	10	# some asynchronous thread of execution
11	$Coro::main->resume;
12	print "in coroutine again, switching back\n";
13	$Coro::main->resume;
14	};	11	};
15		12
16	print "in main, switching to coroutine\n";	13	# alternatively create an async coroutine like this:
17	$new->resume;	14
18	print "back in main, switch to coroutine again\n";	15	sub some_func : Coro {
19	$new->resume;	16	# some more async code
20	print "back in main\n";	17	}
		18
		19	cede;
21		20
22	=head1 DESCRIPTION	21	=head1 DESCRIPTION
23		22
24	This module implements coroutines. Coroutines, similar to continuations,	23	This module collection manages coroutines. Coroutines are similar to
25	allow you to run more than one "thread of execution" in parallel. Unlike	24	threads but don't run in parallel.
26	threads this, only voluntary switching is used so locking problems are
27	greatly reduced.
28		25
29	Although this is the "main" module of the Coro family it provides only	26	In this module, coroutines are defined as "callchain + lexical variables
30	low-level functionality. See L<Coro::Process> and related modules for a	27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
31	more useful process abstraction including scheduling.	28	callchain, it's own set of lexicals and it's own set of perl's most
		29	important global variables.
		30
		31	=cut
		32
		33	package Coro;
		34
		35	use strict;
		36	no warnings "uninitialized";
		37
		38	use Coro::State;
		39
		40	use base qw(Coro::State Exporter);
		41
		42	our $idle; # idle handler
		43	our $main; # main coroutine
		44	our $current; # current coroutine
		45
		46	our $VERSION = '3.01';
		47
		48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
		49	our %EXPORT_TAGS = (
		50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		51	);
		52	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
		53
		54	{
		55	my @async;
		56	my $init;
		57
		58	# this way of handling attributes simply is NOT scalable ;()
		59	sub import {
		60	no strict 'refs';
		61
		62	Coro->export_to_level (1, @_);
		63
		64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		66	my ($package, $ref) = (shift, shift);
		67	my @attrs;
		68	for (@_) {
		69	if ($_ eq "Coro") {
		70	push @async, $ref;
		71	unless ($init++) {
		72	eval q{
		73	sub INIT {
		74	&async(pop @async) while @async;
		75	}
		76	};
		77	}
		78	} else {
		79	push @attrs, $_;
		80	}
		81	}
		82	return $old ? $old->($package, $ref, @attrs) : @attrs;
		83	};
		84	}
		85
		86	}
32		87
33	=over 4	88	=over 4
34		89
35	=cut
36
37	package Coro;
38
39	BEGIN {
40	$VERSION = 0.01;
41
42	require XSLoader;
43	XSLoader::load Coro, $VERSION;
44	}
45
46	=item $main	90	=item $main
47		91
48	This coroutine represents the main program.	92	This coroutine represents the main program.
49		93
50	=item $current	94	=cut
51		95
		96	$main = new Coro;
		97
		98	=item $current (or as function: current)
		99
52	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	100	The current coroutine (the last coroutine switched to). The initial value
		101	is C<$main> (of course).
53		102
54	=cut	103	This variable is B<strictly> I<read-only>. It is provided for performance
		104	reasons. If performance is not essentiel you are encouraged to use the
		105	C<Coro::current> function instead.
55		106
56	$main = $current = _newprocess {	107	=cut
57	# never being called	108
		109	# maybe some other module used Coro::Specific before...
		110	$main->{specific} = $current->{specific}
		111	if $current;
		112
		113	_set_current $main;
		114
		115	sub current() { $current }
		116
		117	=item $idle
		118
		119	A callback that is called whenever the scheduler finds no ready coroutines
		120	to run. The default implementation prints "FATAL: deadlock detected" and
		121	exits, because the program has no other way to continue.
		122
		123	This hook is overwritten by modules such as C<Coro::Timer> and
		124	C<Coro::Event> to wait on an external event that hopefully wake up a
		125	coroutine so the scheduler can run it.
		126
		127	Please note that if your callback recursively invokes perl (e.g. for event
		128	handlers), then it must be prepared to be called recursively.
		129
		130	=cut
		131
		132	$idle = sub {
		133	require Carp;
		134	Carp::croak ("FATAL: deadlock detected");
58	};	135	};
59		136
60	=item $error, $error_msg, $error_coro	137	# this coroutine is necessary because a coroutine
		138	# cannot destroy itself.
		139	my @destroy;
		140	my $manager; $manager = new Coro sub {
		141	while () {
		142	# by overwriting the state object with the manager we destroy it
		143	# while still being able to schedule this coroutine (in case it has
		144	# been readied multiple times. this is harmless since the manager
		145	# can be called as many times as neccessary and will always
		146	# remove itself from the runqueue
		147	while (@destroy) {
		148	my $coro = pop @destroy;
		149	$coro->{status} \|\|= [];
		150	$_->ready for @{delete $coro->{join} \|\| []};
61		151
62	This coroutine will be called on fatal errors. C<$error_msg> and	152	# the next line destroys the coro state, but keeps the
63	C<$error_coro> return the error message and the error-causing coroutine,	153	# coroutine itself intact (we basically make it a zombie
64	respectively.	154	# coroutine that always runs the manager thread, so it's possible
65		155	# to transfer() to this coroutine).
66	=cut	156	$coro->_clone_state_from ($manager);
67		157	}
68	$error_msg =	158	&schedule;
69	$error_coro = undef;	159	}
70
71	$error = _newprocess {
72	print STDERR "FATAL: $error_msg\nprogram aborted\n";
73	exit 250;
74	};	160	};
75		161
76	=item $coro = new $coderef [, @args]	162	# static methods. not really.
77		163
78	Create a new coroutine and return it. The first C<resume> call to this	164	=back
79	coroutine will start execution at the given coderef. If it returns it
80	should return a coroutine to switch to. If, after returning, the coroutine
81	is C<resume>d again it starts execution again at the givne coderef.
82		165
		166	=head2 STATIC METHODS
		167
		168	Static methods are actually functions that operate on the current coroutine only.
		169
		170	=over 4
		171
		172	=item async { ... } [@args...]
		173
		174	Create a new asynchronous coroutine and return it's coroutine object
		175	(usually unused). When the sub returns the new coroutine is automatically
		176	terminated.
		177
		178	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		179
		180	When the coroutine dies, the program will exit, just as in the main
		181	program.
		182
		183	# create a new coroutine that just prints its arguments
		184	async {
		185	print "@_\n";
		186	} 1,2,3,4;
		187
83	=cut	188	=cut
		189
		190	sub async(&@) {
		191	my $pid = new Coro @_;
		192	$pid->ready;
		193	$pid
		194	}
		195
		196	=item schedule
		197
		198	Calls the scheduler. Please note that the current coroutine will not be put
		199	into the ready queue, so calling this function usually means you will
		200	never be called again unless something else (e.g. an event handler) calls
		201	ready.
		202
		203	The canonical way to wait on external events is this:
		204
		205	{
		206	# remember current coroutine
		207	my $current = $Coro::current;
		208
		209	# register a hypothetical event handler
		210	on_event_invoke sub {
		211	# wake up sleeping coroutine
		212	$current->ready;
		213	undef $current;
		214	};
		215
		216	# call schedule until event occured.
		217	# in case we are woken up for other reasons
		218	# (current still defined), loop.
		219	Coro::schedule while $current;
		220	}
		221
		222	=item cede
		223
		224	"Cede" to other coroutines. This function puts the current coroutine into the
		225	ready queue and calls C<schedule>, which has the effect of giving up the
		226	current "timeslice" to other coroutines of the same or higher priority.
		227
		228	=item terminate [arg...]
		229
		230	Terminates the current coroutine with the given status values (see L<cancel>).
		231
		232	=cut
		233
		234	sub terminate {
		235	$current->cancel (@_);
		236	}
		237
		238	=back
		239
		240	# dynamic methods
		241
		242	=head2 COROUTINE METHODS
		243
		244	These are the methods you can call on coroutine objects.
		245
		246	=over 4
		247
		248	=item new Coro \&sub [, @args...]
		249
		250	Create a new coroutine and return it. When the sub returns the coroutine
		251	automatically terminates as if C<terminate> with the returned values were
		252	called. To make the coroutine run you must first put it into the ready queue
		253	by calling the ready method.
		254
		255	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		256
		257	=cut
		258
		259	sub _run_coro {
		260	terminate &{+shift};
		261	}
84		262
85	sub new {	263	sub new {
86	my $class = $_[0];	264	my $class = shift;
87	my $proc = $_[1];	265
88	bless _newprocess {	266	$class->SUPER::new (\&_run_coro, @_)
89	do {	267	}
90	eval { &$proc->resume };	268
91	if ($@) {	269	=item $success = $coroutine->ready
92	($error_msg, $error_coro) = ($@, $current);	270
93	$error->resume;	271	Put the given coroutine into the ready queue (according to it's priority)
		272	and return true. If the coroutine is already in the ready queue, do nothing
		273	and return false.
		274
		275	=item $is_ready = $coroutine->is_ready
		276
		277	Return wether the coroutine is currently the ready queue or not,
		278
		279	=item $coroutine->cancel (arg...)
		280
		281	Terminates the given coroutine and makes it return the given arguments as
		282	status (default: the empty list).
		283
		284	=cut
		285
		286	sub cancel {
		287	my $self = shift;
		288	$self->{status} = [@_];
		289	push @destroy, $self;
		290	$manager->ready;
		291	&schedule if $current == $self;
		292	}
		293
		294	=item $coroutine->join
		295
		296	Wait until the coroutine terminates and return any values given to the
		297	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		298	from multiple coroutine.
		299
		300	=cut
		301
		302	sub join {
		303	my $self = shift;
		304	unless ($self->{status}) {
		305	push @{$self->{join}}, $current;
		306	&schedule;
		307	}
		308	wantarray ? @{$self->{status}} : $self->{status}[0];
		309	}
		310
		311	=item $oldprio = $coroutine->prio ($newprio)
		312
		313	Sets (or gets, if the argument is missing) the priority of the
		314	coroutine. Higher priority coroutines get run before lower priority
		315	coroutines. Priorities are small signed integers (currently -4 .. +3),
		316	that you can refer to using PRIO_xxx constants (use the import tag :prio
		317	to get then):
		318
		319	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		320	3 > 1 > 0 > -1 > -3 > -4
		321
		322	# set priority to HIGH
		323	current->prio(PRIO_HIGH);
		324
		325	The idle coroutine ($Coro::idle) always has a lower priority than any
		326	existing coroutine.
		327
		328	Changing the priority of the current coroutine will take effect immediately,
		329	but changing the priority of coroutines in the ready queue (but not
		330	running) will only take effect after the next schedule (of that
		331	coroutine). This is a bug that will be fixed in some future version.
		332
		333	=item $newprio = $coroutine->nice ($change)
		334
		335	Similar to C<prio>, but subtract the given value from the priority (i.e.
		336	higher values mean lower priority, just as in unix).
		337
		338	=item $olddesc = $coroutine->desc ($newdesc)
		339
		340	Sets (or gets in case the argument is missing) the description for this
		341	coroutine. This is just a free-form string you can associate with a coroutine.
		342
		343	=cut
		344
		345	sub desc {
		346	my $old = $_[0]{desc};
		347	$_[0]{desc} = $_[1] if @_ > 1;
		348	$old;
		349	}
		350
		351	=back
		352
		353	=head2 GLOBAL FUNCTIONS
		354
		355	=over 4
		356
		357	=item Coro::nready
		358
		359	Returns the number of coroutines that are currently in the ready state,
		360	i.e. that can be swicthed to. The value C<0> means that the only runnable
		361	coroutine is the currently running one, so C<cede> would have no effect,
		362	and C<schedule> would cause a deadlock unless there is an idle handler
		363	that wakes up some coroutines.
		364
		365	=item unblock_sub { ... }
		366
		367	This utility function takes a BLOCK or code reference and "unblocks" it,
		368	returning the new coderef. This means that the new coderef will return
		369	immediately without blocking, returning nothing, while the original code
		370	ref will be called (with parameters) from within its own coroutine.
		371
		372	The reason this fucntion exists is that many event libraries (such as the
		373	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		374	of thread-safety). This means you must not block within event callbacks,
		375	otherwise you might suffer from crashes or worse.
		376
		377	This function allows your callbacks to block by executing them in another
		378	coroutine where it is safe to block. One example where blocking is handy
		379	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		380	disk.
		381
		382	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		383	creating event callbacks that want to block.
		384
		385	=cut
		386
		387	our @unblock_pool;
		388	our @unblock_queue;
		389	our $UNBLOCK_POOL_SIZE = 2;
		390
		391	sub unblock_handler_ {
		392	while () {
		393	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		394	$cb->(@arg);
		395
		396	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		397	push @unblock_pool, $Coro::current;
		398	schedule;
		399	}
		400	}
		401
		402	our $unblock_scheduler = async {
		403	while () {
		404	while (my $cb = pop @unblock_queue) {
		405	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		406	$handler->{arg} = $cb;
		407	$handler->ready;
		408	cede;
94	}	409	}
95	} while (1);
96	}, $class;
97	}
98		410
99	=item $coro->resume	411	schedule;
		412	}
		413	};
100		414
101	Resume execution at the given coroutine.	415	sub unblock_sub(&) {
		416	my $cb = shift;
102		417
103	=cut	418	sub {
104		419	push @unblock_queue, [$cb, @_];
105	my $prev;	420	$unblock_scheduler->ready;
106		421	}
107	sub resume {
108	$prev = $current; $current = $_[0];
109	_transfer($prev, $current);
110	}	422	}
		423
		424	=back
		425
		426	=cut
111		427
112	1;	428	1;
113		429
114	=back	430	=head1 BUGS/LIMITATIONS
115		431
116	=head1 BUGS	432	- you must make very sure that no coro is still active on global
		433	destruction. very bad things might happen otherwise (usually segfaults).
117		434
118	This module has not yet been extensively tested.	435	- this module is not thread-safe. You should only ever use this module
		436	from the same thread (this requirement might be losened in the future
		437	to allow per-thread schedulers, but Coro::State does not yet allow
		438	this).
119		439
120	=head1 SEE ALSO	440	=head1 SEE ALSO
121		441
122	L<Coro::Process>, L<Coro::Signal>.	442	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		443
		444	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		445
		446	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		447
		448	Embedding: L<Coro:MakeMaker>
123		449
124	=head1 AUTHOR	450	=head1 AUTHOR
125		451
126	Marc Lehmann <pcg@goof.com>	452	Marc Lehmann <schmorp@schmorp.de>
127	http://www.goof.com/pcg/marc/	453	http://home.schmorp.de/
128		454
129	=cut	455	=cut
130		456

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Comparing Coro/Coro.pm (file contents): Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs. Revision 1.97 by root, Mon Dec 4 13:47:56 2006 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs.
Revision 1.97 by root, Mon Dec 4 13:47:56 2006 UTC