[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 1.17 by root, Thu Jul 19 02:45:09 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	yield;
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	=cut
		29
		30	package Coro;
		31
		32	use Coro::State;
		33
		34	use base Exporter;
		35
		36	$VERSION = 0.08;
		37
		38	@EXPORT = qw(async yield schedule terminate);
		39	@EXPORT_OK = qw($current);
		40
		41	{
		42	use subs 'async';
		43
		44	my @async;
		45
		46	# this way of handling attributes simply is NOT scalable ;()
		47	sub import {
		48	Coro->export_to_level(1, @_);
		49	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		50	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		51	my ($package, $ref) = (shift, shift);
		52	my @attrs;
		53	for (@_) {
		54	if ($_ eq "Coro") {
		55	push @async, $ref;
		56	} else {
		57	push @attrs, $_;
		58	}
		59	}
		60	return $old ? $old->($package, $ref, @attrs) : @attrs;
		61	};
		62	}
		63
		64	sub INIT {
		65	async pop @async while @async;
		66	}
		67	}
		68
		69	=item $main
		70
		71	This coroutine represents the main program.
		72
		73	=cut
		74
		75	our $main = new Coro;
		76
		77	=item $current
		78
		79	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		80
		81	=cut
		82
		83	# maybe some other module used Coro::Specific before...
		84	if ($current) {
		85	$main->{specific} = $current->{specific};
		86	}
		87
		88	our $current = $main;
		89
		90	=item $idle
		91
		92	The coroutine to switch to when no other coroutine is running. The default
		93	implementation prints "FATAL: deadlock detected" and exits.
		94
		95	=cut
		96
		97	# should be done using priorities :(
		98	our $idle = new Coro sub {
		99	print STDERR "FATAL: deadlock detected\n";
		100	exit(51);
		101	};
		102
		103	# we really need priorities...
		104	my @ready; # the ready queue. hehe, rather broken ;)
		105
		106	# static methods. not really.
		107
		108	=head2 STATIC METHODS
		109
		110	Static methods are actually functions that operate on the current process only.
34		111
35	=over 4	112	=over 4
36		113
37	=cut	114	=item async { ... } [@args...]
38		115
39	package Coro;	116	Create a new asynchronous process and return it's process object
		117	(usually unused). When the sub returns the new process is automatically
		118	terminated.
40		119
41	BEGIN {	120	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	121	async {
		122	print "@_\n";
		123	} 1,2,3,4;
43		124
44	require XSLoader;	125	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	126	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		127
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	128	=cut
		129
		130	sub async(&@) {
		131	my $pid = new Coro @_;
		132	$pid->ready;
		133	$pid;
		134	}
		135
		136	=item schedule
		137
		138	Calls the scheduler. Please note that the current process will not be put
		139	into the ready queue, so calling this function usually means you will
		140	never be called again.
		141
		142	=cut
		143
		144	my $prev;
		145
		146	sub schedule {
		147	# should be done using priorities :(
		148	($prev, $current) = ($current, shift @ready \|\| $idle);
		149	Coro::State::transfer($prev, $current);
		150	}
		151
		152	=item yield
		153
		154	Yield to other processes. This function puts the current process into the
		155	ready queue and calls C<schedule>.
		156
		157	=cut
		158
		159	sub yield {
		160	$current->ready;
		161	&schedule;
		162	}
		163
		164	=item terminate
		165
		166	Terminates the current process.
		167
		168	Future versions of this function will allow result arguments.
		169
		170	=cut
		171
		172	sub terminate {
		173	$current->{_results} = [@_];
		174	&schedule;
		175	}
		176
		177	=back
		178
		179	# dynamic methods
		180
		181	=head2 PROCESS METHODS
		182
		183	These are the methods you can call on process objects.
		184
		185	=over 4
		186
		187	=item new Coro \&sub [, @args...]
		188
		189	Create a new process and return it. When the sub returns the process
		190	automatically terminates. To start the process you must first put it into
		191	the ready queue by calling the ready method.
		192
		193	The coderef you submit MUST NOT be a closure that refers to variables
		194	in an outer scope. This does NOT work. Pass arguments into it instead.
		195
		196	=cut
		197
		198	sub _newcoro {
		199	terminate &{+shift};
		200	}
59		201
60	sub new {	202	sub new {
61	my $class = $_[0];	203	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	204	bless {
63	bless _newprocess {	205	_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;	206	}, $class;
73	}	207	}
74		208
75	=item $prev->transfer($next)	209	=item $process->ready
76		210
77	Save the state of the current subroutine in C<$prev> and switch to the	211	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		212
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	213	=cut
96		214
97	# I call the _transfer function from a perl function	215	sub ready {
98	# because that way perl saves all important things on	216	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	}	217	}
104		218
105	=item $error, $error_msg, $error_coro	219	=back
106		220
107	This coroutine will be called on fatal errors. C<$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	221	=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		222
121	1;	223	1;
122		224
123	=back	225	=head1 BUGS/LIMITATIONS
124		226
125	=head1 BUGS	227	- could be faster, especially when the core would introduce special
126		228	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	229	- there is still a memleak on coroutine termination that I could not
		230	identify. Could be as small as a single SV.
		231	- this module is not well-tested.
		232	- if variables or arguments "disappear" (become undef) or become
		233	corrupted please contact the author so he cen iron out the
		234	remaining bugs.
		235	- this module is not thread-safe. You must only ever use this module from
		236	the same thread (this requirement might be loosened in the future to
		237	allow per-thread schedulers, but Coro::Satte does not yet allow this).
128		238
129	=head1 SEE ALSO	239	=head1 SEE ALSO
130		240
131	L<Coro::Process>, L<Coro::Signal>.	241	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		242	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
132		243
133	=head1 AUTHOR	244	=head1 AUTHOR
134		245
135	Marc Lehmann <pcg@goof.com>	246	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	247	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 1.17 by root, Thu Jul 19 02:45:09 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 1.17 by root, Thu Jul 19 02:45:09 2001 UTC