[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 1.25 by root, Wed Jul 25 21:12:57 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	$VERSION = 0.12;
		42
		43	@EXPORT = qw(async cede schedule terminate current);
		44	@EXPORT_OK = qw($current);
		45
		46	{
		47	my @async;
		48
		49	# this way of handling attributes simply is NOT scalable ;()
		50	sub import {
		51	Coro->export_to_level(1, @_);
		52	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		53	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		54	my ($package, $ref) = (shift, shift);
		55	my @attrs;
		56	for (@_) {
		57	if ($_ eq "Coro") {
		58	push @async, $ref;
		59	} else {
		60	push @attrs, $_;
		61	}
		62	}
		63	return $old ? $old->($package, $ref, @attrs) : @attrs;
		64	};
		65	}
		66
		67	sub INIT {
		68	&async(pop @async) while @async;
		69	}
		70	}
		71
		72	=item $main
		73
		74	This coroutine represents the main program.
		75
		76	=cut
		77
		78	our $main = new Coro;
		79
		80	=item $current (or as function: current)
		81
		82	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		83
		84	=cut
		85
		86	# maybe some other module used Coro::Specific before...
		87	if ($current) {
		88	$main->{specific} = $current->{specific};
		89	}
		90
		91	our $current = $main;
		92
		93	sub current() { $current }
		94
		95	=item $idle
		96
		97	The coroutine to switch to when no other coroutine is running. The default
		98	implementation prints "FATAL: deadlock detected" and exits.
		99
		100	=cut
		101
		102	# should be done using priorities :(
		103	our $idle = new Coro sub {
		104	print STDERR "FATAL: deadlock detected\n";
		105	exit(51);
		106	};
		107
		108	# this coroutine is necessary because a coroutine
		109	# cannot destroy itself.
		110	my @destroy;
		111	my $manager = new Coro sub {
		112	while() {
		113	delete ((pop @destroy)->{_coro_state}) while @destroy;
		114	&schedule;
		115	}
		116	};
		117
		118	# we really need priorities...
		119	my @ready; # the ready queue. hehe, rather broken ;)
		120
		121	# static methods. not really.
		122
		123	=head2 STATIC METHODS
		124
		125	Static methods are actually functions that operate on the current process only.
34		126
35	=over 4	127	=over 4
36		128
37	=cut	129	=item async { ... } [@args...]
38		130
39	package Coro;	131	Create a new asynchronous process and return it's process object
		132	(usually unused). When the sub returns the new process is automatically
		133	terminated.
40		134
41	BEGIN {	135	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	136	async {
		137	print "@_\n";
		138	} 1,2,3,4;
43		139
44	require XSLoader;	140	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	141	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		142
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	143	=cut
		144
		145	sub async(&@) {
		146	my $pid = new Coro @_;
		147	$manager->ready; # this ensures that the stack is cloned from the manager
		148	$pid->ready;
		149	$pid;
		150	}
		151
		152	=item schedule
		153
		154	Calls the scheduler. Please note that the current process will not be put
		155	into the ready queue, so calling this function usually means you will
		156	never be called again.
		157
		158	=cut
		159
		160	my $prev;
		161
		162	sub schedule {
		163	# should be done using priorities :(
		164	($prev, $current) = ($current, shift @ready \|\| $idle);
		165	Coro::State::transfer($prev, $current);
		166	}
		167
		168	=item cede
		169
		170	"Cede" to other processes. This function puts the current process into the
		171	ready queue and calls C<schedule>, which has the effect of giving up the
		172	current "timeslice" to other coroutines of the same or higher priority.
		173
		174	=cut
		175
		176	sub cede {
		177	$current->ready;
		178	&schedule;
		179	}
		180
		181	=item terminate
		182
		183	Terminates the current process.
		184
		185	Future versions of this function will allow result arguments.
		186
		187	=cut
		188
		189	sub terminate {
		190	push @destroy, $current;
		191	$manager->ready;
		192	&schedule;
		193	# NORETURN
		194	}
		195
		196	=back
		197
		198	# dynamic methods
		199
		200	=head2 PROCESS METHODS
		201
		202	These are the methods you can call on process objects.
		203
		204	=over 4
		205
		206	=item new Coro \&sub [, @args...]
		207
		208	Create a new process and return it. When the sub returns the process
		209	automatically terminates. To start the process you must first put it into
		210	the ready queue by calling the ready method.
		211
		212	The coderef you submit MUST NOT be a closure that refers to variables
		213	in an outer scope. This does NOT work. Pass arguments into it instead.
		214
		215	=cut
		216
		217	sub _newcoro {
		218	terminate &{+shift};
		219	}
59		220
60	sub new {	221	sub new {
61	my $class = $_[0];	222	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	223	bless {
63	bless _newprocess {	224	_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;	225	}, $class;
73	}	226	}
74		227
75	=item $prev->transfer($next)	228	=item $process->ready
76		229
77	Save the state of the current subroutine in C<$prev> and switch to the	230	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		231
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	232	=cut
96		233
97	# I call the _transfer function from a perl function	234	sub ready {
98	# because that way perl saves all important things on	235	push @ready, $_[0];
99	# the stack. Actually, I'd do it from within XS, but
100	# I couldn't get it to work.
101	sub transfer {
102	_transfer($_[0], $_[1]);
103	}	236	}
104		237
105	=item $error, $error_msg, $error_coro	238	=back
106		239
107	This coroutine will be called on fatal errors. C<$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	240	=cut
112
113	$error_msg =
114	$error_coro = undef;
115
116	$error = _newprocess {
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";
118	exit 50;
119	};
120		241
121	1;	242	1;
122		243
123	=back	244	=head1 BUGS/LIMITATIONS
124		245
125	=head1 BUGS	246	- could be faster, especially when the core would introduce special
126		247	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	248	- there is still a memleak on coroutine termination that I could not
		249	identify. Could be as small as a single SV.
		250	- this module is not well-tested.
		251	- if variables or arguments "disappear" (become undef) or become
		252	corrupted please contact the author so he cen iron out the
		253	remaining bugs.
		254	- this module is not thread-safe. You must only ever use this module from
		255	the same thread (this requirement might be loosened in the future to
		256	allow per-thread schedulers, but Coro::State does not yet allow this).
128		257
129	=head1 SEE ALSO	258	=head1 SEE ALSO
130		259
131	L<Coro::Process>, L<Coro::Signal>.	260	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		261	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		262	L<Coro::L<Coro::Handle>, L<Coro::Socket>.
132		263
133	=head1 AUTHOR	264	=head1 AUTHOR
134		265
135	Marc Lehmann <pcg@goof.com>	266	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	267	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 1.25 by root, Wed Jul 25 21:12:57 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 1.25 by root, Wed Jul 25 21:12:57 2001 UTC