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

Comparing Coro/Coro.pm (file contents):
Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs.
Revision 1.35 by root, Mon Sep 24 00:16:30 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	This module is still experimental, see the BUGS section below.
32	low-level functionality. See L<Coro::Process> and related modules for a	27
33	more useful process abstraction including scheduling.	28	In this module, coroutines are defined as "callchain + lexical variables
		29	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
		30	callchain, it's own set of lexicals and it's own set of perl's most
		31	important global variables.
		32
		33	=cut
		34
		35	package Coro;
		36
		37	use Coro::State;
		38
		39	use base Exporter;
		40
		41	$VERSION = 0.5;
		42
		43	@EXPORT = qw(async cede schedule terminate current);
		44	%EXPORT_TAGS = (
		45	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		46	);
		47	@EXPORT_OK = @{$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 = new Coro sub {
		120	while() {
		121	delete ((pop @destroy)->{_coro_state}) while @destroy;
		122	&schedule;
		123	}
		124	};
		125
		126	# static methods. not really.
		127
		128	=head2 STATIC METHODS
		129
		130	Static methods are actually functions that operate on the current process only.
34		131
35	=over 4	132	=over 4
36		133
37	=cut	134	=item async { ... } [@args...]
38		135
39	package Coro;	136	Create a new asynchronous process and return it's process object
		137	(usually unused). When the sub returns the new process is automatically
		138	terminated.
40		139
41	BEGIN {	140	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	141	async {
		142	print "@_\n";
		143	} 1,2,3,4;
43		144
44	require XSLoader;	145	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	146	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		147
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	148	=cut
		149
		150	sub async(&@) {
		151	my $pid = new Coro @_;
		152	$manager->ready; # this ensures that the stack is cloned from the manager
		153	$pid->ready;
		154	$pid;
		155	}
		156
		157	=item schedule
		158
		159	Calls the scheduler. Please note that the current process will not be put
		160	into the ready queue, so calling this function usually means you will
		161	never be called again.
		162
		163	=cut
		164
		165	=item cede
		166
		167	"Cede" to other processes. This function puts the current process into the
		168	ready queue and calls C<schedule>, which has the effect of giving up the
		169	current "timeslice" to other coroutines of the same or higher priority.
		170
		171	=cut
		172
		173	=item terminate
		174
		175	Terminates the current process.
		176
		177	Future versions of this function will allow result arguments.
		178
		179	=cut
		180
		181	sub terminate {
		182	$current->cancel;
		183	&schedule;
		184	die; # NORETURN
		185	}
		186
		187	=back
		188
		189	# dynamic methods
		190
		191	=head2 PROCESS METHODS
		192
		193	These are the methods you can call on process objects.
		194
		195	=over 4
		196
		197	=item new Coro \&sub [, @args...]
		198
		199	Create a new process and return it. When the sub returns the process
		200	automatically terminates. To start the process you must first put it into
		201	the ready queue by calling the ready method.
		202
		203	The coderef you submit MUST NOT be a closure that refers to variables
		204	in an outer scope. This does NOT work. Pass arguments into it instead.
		205
		206	=cut
		207
		208	sub _newcoro {
		209	terminate &{+shift};
		210	}
59		211
60	sub new {	212	sub new {
61	my $class = $_[0];	213	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	214	bless {
63	bless _newprocess {	215	_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;	216	}, $class;
73	}	217	}
74		218
75	=item $prev->transfer($next)	219	=item $process->ready
76		220
77	Save the state of the current subroutine in C<$prev> and switch to the	221	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		222
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> or C<$@> or any other special or non
83	special variables. So remember that every function call that might call
84	C<transfer> (such as C<Coro::Channel::put>) might clobber any global
85	and/or special variables. Yes, this is by design ;) You cna always create
86	your own process abstraction model that saves these variables.
87
88	The easiest way to do this is to create your own scheduling primitive like this:
89
90	sub schedule {
91	local ($_, $@, ...);
92	$old->transfer($new);
93	}
94
95	=cut	223	=cut
96		224
97	# I call the _transfer function from a perl function	225	=item $process->cancel
98	# because that way perl saves all important things on
99	# the stack. Actually, I'd do it from within XS, but
100	# I couldn't get it to work.
101	sub transfer {
102	_transfer($_[0], $_[1]);
103	}
104		226
105	=item $error, $error_msg, $error_coro	227	Like C<terminate>, but terminates the specified process instead.
106		228
107	This coroutine will be called on fatal errors. C<$error_msg> and
108	C<$error_coro> return the error message and the error-causing coroutine
109	(NOT an object) respectively. This API might change.
110
111	=cut	229	=cut
112		230
113	$error_msg =	231	sub cancel {
114	$error_coro = undef;	232	push @destroy, $_[0];
		233	$manager->ready;
		234	&schedule if $current == $_[0];
		235	}
115		236
116	$error = _newprocess {	237	=item $oldprio = $process->prio($newprio)
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	238
118	exit 50;	239	Sets the priority of the process. Higher priority processes get run before
119	};	240	lower priority processes. Priorities are smalled signed integer (currently
		241	-4 .. +3), that you can refer to using PRIO_xxx constants (use the import
		242	tag :prio to get then):
		243
		244	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		245	3 > 1 > 0 > -1 > -3 > -4
		246
		247	# set priority to HIGH
		248	current->prio(PRIO_HIGH);
		249
		250	The idle coroutine ($Coro::idle) always has a lower priority than any
		251	existing coroutine.
		252
		253	Changing the priority of the current process will take effect immediately,
		254	but changing the priority of processes in the ready queue (but not
		255	running) will only take effect after the next schedule (of that
		256	process). This is a bug that will be fixed in some future version.
		257
		258	=cut
		259
		260	sub prio {
		261	my $old = $_[0]{prio};
		262	$_[0]{prio} = $_[1] if @_ > 1;
		263	$old;
		264	}
		265
		266	=item $newprio = $process->nice($change)
		267
		268	Similar to C<prio>, but subtract the given value from the priority (i.e.
		269	higher values mean lower priority, just as in unix).
		270
		271	=cut
		272
		273	sub nice {
		274	$_[0]{prio} -= $_[1];
		275	}
		276
		277	=back
		278
		279	=cut
120		280
121	1;	281	1;
122		282
123	=back	283	=head1 BUGS/LIMITATIONS
124		284
125	=head1 BUGS	285	- you must make very sure that no coro is still active on global destruction.
126		286	very bad things might happen otherwise (usually segfaults).
127	This module has not yet been extensively tested.	287	- this module is not thread-safe. You must only ever use this module from
		288	the same thread (this requirement might be loosened in the future to
		289	allow per-thread schedulers, but Coro::State does not yet allow this).
128		290
129	=head1 SEE ALSO	291	=head1 SEE ALSO
130		292
131	L<Coro::Process>, L<Coro::Signal>.	293	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		294	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		295	L<Coro::Handle>, L<Coro::Socket>.
132		296
133	=head1 AUTHOR	297	=head1 AUTHOR
134		298
135	Marc Lehmann <pcg@goof.com>	299	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	300	http://www.goof.com/pcg/marc/

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Comparing Coro/Coro.pm (file contents): Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs. Revision 1.35 by root, Mon Sep 24 00:16:30 2001 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs.
Revision 1.35 by root, Mon Sep 24 00:16:30 2001 UTC