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

Comparing Coro/Coro.pm (file contents):
Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.42 by root, Tue Nov 6 20:37:20 2001 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - create and manage simple 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	$new->transfer($main);
12	print "in coroutine again, switching back\n";
13	$new->transfer($main);
14	};	11	};
15		12
16	$main = new Coro;	13	# alternatively create an async process like this:
17		14
18	print "in main, switching to coroutine\n";	15	sub some_func : Coro {
19	$main->transfer($new);	16	# some more async code
20	print "back in main, switch to coroutine again\n";	17	}
21	$main->transfer($new);	18
22	print "back in main\n";	19	cede;
23		20
24	=head1 DESCRIPTION	21	=head1 DESCRIPTION
25		22
26	This module implements coroutines. Coroutines, similar to continuations,	23	This module collection manages coroutines. Coroutines are similar to
27	allow you to run more than one "thread of execution" in parallel. Unlike	24	threads but don't run in parallel.
28	threads this, only voluntary switching is used so locking problems are
29	greatly reduced.
30		25
31	Although this is the "main" module of the Coro family it provides only	26	In this module, coroutines are defined as "callchain + lexical variables
32	low-level functionality. See L<Coro::Process> and related modules for a	27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
33	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	no warnings qw(uninitialized);
		36
		37	use Coro::State;
		38
		39	use base Exporter;
		40
		41	$VERSION = 0.52;
		42
		43	@EXPORT = qw(async cede schedule terminate current);
		44	%EXPORT_TAGS = (
		45	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		46	);
		47	@EXPORT_OK = @{$EXPORT_TAGS{prio}};
		48
		49	{
		50	my @async;
		51	my $init;
		52
		53	# this way of handling attributes simply is NOT scalable ;()
		54	sub import {
		55	Coro->export_to_level(1, @_);
		56	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		57	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		58	my ($package, $ref) = (shift, shift);
		59	my @attrs;
		60	for (@_) {
		61	if ($_ eq "Coro") {
		62	push @async, $ref;
		63	unless ($init++) {
		64	eval q{
		65	sub INIT {
		66	&async(pop @async) while @async;
		67	}
		68	};
		69	}
		70	} else {
		71	push @attrs, $_;
		72	}
		73	}
		74	return $old ? $old->($package, $ref, @attrs) : @attrs;
		75	};
		76	}
		77
		78	}
		79
		80	=item $main
		81
		82	This coroutine represents the main program.
		83
		84	=cut
		85
		86	our $main = new Coro;
		87
		88	=item $current (or as function: current)
		89
		90	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		91
		92	=cut
		93
		94	# maybe some other module used Coro::Specific before...
		95	if ($current) {
		96	$main->{specific} = $current->{specific};
		97	}
		98
		99	our $current = $main;
		100
		101	sub current() { $current }
		102
		103	=item $idle
		104
		105	The coroutine to switch to when no other coroutine is running. The default
		106	implementation prints "FATAL: deadlock detected" and exits.
		107
		108	=cut
		109
		110	# should be done using priorities :(
		111	our $idle = new Coro sub {
		112	print STDERR "FATAL: deadlock detected\n";
		113	exit(51);
		114	};
		115
		116	# this coroutine is necessary because a coroutine
		117	# cannot destroy itself.
		118	my @destroy;
		119	my $manager;
		120	$manager = new Coro sub {
		121	while() {
		122	# by overwriting the state object with the manager we destroy it
		123	# while still being able to schedule this coroutine (in case it has
		124	# been readied multiple times. this is harmless since the manager
		125	# can be called as many times as neccessary and will always
		126	# remove itself from the runqueue
		127	while (@destroy) {
		128	my $coro = pop @destroy;
		129	$coro->{status} \|\|= [];
		130	$_->ready for @{delete $coro->{join} \|\| []};
		131	$coro->{_coro_state} = $manager->{_coro_state};
		132	}
		133	&schedule;
		134	}
		135	};
		136
		137	# static methods. not really.
		138
		139	=head2 STATIC METHODS
		140
		141	Static methods are actually functions that operate on the current process only.
34		142
35	=over 4	143	=over 4
36		144
37	=cut	145	=item async { ... } [@args...]
38		146
39	package Coro;	147	Create a new asynchronous process and return it's process object
		148	(usually unused). When the sub returns the new process is automatically
		149	terminated.
40		150
41	BEGIN {	151	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	152	async {
		153	print "@_\n";
		154	} 1,2,3,4;
43		155
44	require XSLoader;	156	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	157	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		158
48	=item $coro = new [$coderef [, @args]]
49
50	Create a new coroutine and return it. The first C<transfer> call to this
51	coroutine will start execution at the given coderef. If, the subroutine
52	returns it will be executed again.
53
54	If the coderef is omitted this function will create a new "empty"
55	coroutine, i.e. a coroutine that cannot be transfered to but can be used
56	to save the current coroutine in.
57
58	=cut	159	=cut
		160
		161	sub async(&@) {
		162	my $pid = new Coro @_;
		163	$manager->ready; # this ensures that the stack is cloned from the manager
		164	$pid->ready;
		165	$pid;
		166	}
		167
		168	=item schedule
		169
		170	Calls the scheduler. Please note that the current process will not be put
		171	into the ready queue, so calling this function usually means you will
		172	never be called again.
		173
		174	=cut
		175
		176	=item cede
		177
		178	"Cede" to other processes. This function puts the current process into the
		179	ready queue and calls C<schedule>, which has the effect of giving up the
		180	current "timeslice" to other coroutines of the same or higher priority.
		181
		182	=cut
		183
		184	=item terminate [arg...]
		185
		186	Terminates the current process.
		187
		188	Future versions of this function will allow result arguments.
		189
		190	=cut
		191
		192	sub terminate {
		193	$current->{status} = [@_];
		194	$current->cancel;
		195	&schedule;
		196	die; # NORETURN
		197	}
		198
		199	=back
		200
		201	# dynamic methods
		202
		203	=head2 PROCESS METHODS
		204
		205	These are the methods you can call on process objects.
		206
		207	=over 4
		208
		209	=item new Coro \&sub [, @args...]
		210
		211	Create a new process and return it. When the sub returns the process
		212	automatically terminates as if C<terminate> with the returned values were
		213	called. To make the process run you must first put it into the ready queue
		214	by calling the ready method.
		215
		216	=cut
		217
		218	sub _newcoro {
		219	terminate &{+shift};
		220	}
59		221
60	sub new {	222	sub new {
61	my $class = $_[0];	223	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	224	bless {
63	bless _newprocess {	225	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
64	do {
65	eval { &$proc };
66	if ($@) {
67	$error_msg = $@;
68	$error_coro = _newprocess { };
69	&transfer($error_coro, $error);
70	}
71	} while (1);
72	}, $class;	226	}, $class;
73	}	227	}
74		228
75	=item $prev->transfer($next)	229	=item $process->ready
76		230
77	Save the state of the current subroutine in $prev and switch to the	231	Put the given process into the ready queue.
78	coroutine saved in $next.
79		232
80	=cut	233	=cut
81		234
82	# I call the _transfer function from a perl function	235	=item $process->cancel
83	# because that way perl saves all important things on
84	# the stack.
85	sub transfer {
86	_transfer($_[0], $_[1]);
87	}
88		236
89	=item $error, $error_msg, $error_coro	237	Like C<terminate>, but terminates the specified process instead.
90		238
91	This coroutine will be called on fatal errors. C<$error_msg> and
92	C<$error_coro> return the error message and the error-causing coroutine
93	(NOT an object) respectively. This API might change.
94
95	=cut	239	=cut
96		240
97	$error_msg =	241	sub cancel {
98	$error_coro = undef;	242	push @destroy, $_[0];
		243	$manager->ready;
		244	&schedule if $current == $_[0];
		245	}
99		246
100	$error = _newprocess {	247	=item $process->join
101	print STDERR "FATAL: $error_msg\nprogram aborted\n";	248
102	exit 50;	249	Wait until the coroutine terminates and return any values given to the
103	};	250	C<terminate> function. C<join> can be called multiple times from multiple
		251	processes.
		252
		253	=cut
		254
		255	sub join {
		256	my $self = shift;
		257	unless ($self->{status}) {
		258	push @{$self->{join}}, $current;
		259	&schedule;
		260	}
		261	wantarray ? @{$self->{status}} : $self->{status}[0];
		262	}
		263
		264	=item $oldprio = $process->prio($newprio)
		265
		266	Sets (or gets, if the argument is missing) the priority of the
		267	process. Higher priority processes get run before lower priority
		268	processes. Priorities are smalled signed integer (currently -4 .. +3),
		269	that you can refer to using PRIO_xxx constants (use the import tag :prio
		270	to get then):
		271
		272	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		273	3 > 1 > 0 > -1 > -3 > -4
		274
		275	# set priority to HIGH
		276	current->prio(PRIO_HIGH);
		277
		278	The idle coroutine ($Coro::idle) always has a lower priority than any
		279	existing coroutine.
		280
		281	Changing the priority of the current process will take effect immediately,
		282	but changing the priority of processes in the ready queue (but not
		283	running) will only take effect after the next schedule (of that
		284	process). This is a bug that will be fixed in some future version.
		285
		286	=cut
		287
		288	sub prio {
		289	my $old = $_[0]{prio};
		290	$_[0]{prio} = $_[1] if @_ > 1;
		291	$old;
		292	}
		293
		294	=item $newprio = $process->nice($change)
		295
		296	Similar to C<prio>, but subtract the given value from the priority (i.e.
		297	higher values mean lower priority, just as in unix).
		298
		299	=cut
		300
		301	sub nice {
		302	$_[0]{prio} -= $_[1];
		303	}
		304
		305	=item $olddesc = $process->desc($newdesc)
		306
		307	Sets (or gets in case the argument is missing) the description for this
		308	process. This is just a free-form string you can associate with a process.
		309
		310	=cut
		311
		312	sub desc {
		313	my $old = $_[0]{desc};
		314	$_[0]{desc} = $_[1] if @_ > 1;
		315	$old;
		316	}
		317
		318	=back
		319
		320	=cut
104		321
105	1;	322	1;
106		323
107	=back	324	=head1 BUGS/LIMITATIONS
108		325
109	=head1 BUGS	326	- you must make very sure that no coro is still active on global destruction.
110		327	very bad things might happen otherwise (usually segfaults).
111	This module has not yet been extensively tested.	328	- this module is not thread-safe. You should only ever use this module from
		329	the same thread (this requirement might be loosened in the future to
		330	allow per-thread schedulers, but Coro::State does not yet allow this).
112		331
113	=head1 SEE ALSO	332	=head1 SEE ALSO
114		333
115	L<Coro::Process>, L<Coro::Signal>.	334	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		335	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		336	L<Coro::Handle>, L<Coro::Socket>.
116		337
117	=head1 AUTHOR	338	=head1 AUTHOR
118		339
119	Marc Lehmann <pcg@goof.com>	340	Marc Lehmann <pcg@goof.com>
120	http://www.goof.com/pcg/marc/	341	http://www.goof.com/pcg/marc/

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Comparing Coro/Coro.pm (file contents): Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs. Revision 1.42 by root, Tue Nov 6 20:37:20 2001 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.42 by root, Tue Nov 6 20:37:20 2001 UTC