[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 1.23 by root, Mon Jul 23 04:23:32 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	$VERSION = 0.10;
		42
		43	@EXPORT = qw(async cede schedule terminate current);
		44	@EXPORT_OK = qw($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	# we really need priorities...
		109	my @ready; # the ready queue. hehe, rather broken ;)
		110
		111	# static methods. not really.
		112
		113	=head2 STATIC METHODS
		114
		115	Static methods are actually functions that operate on the current process only.
34		116
35	=over 4	117	=over 4
36		118
37	=cut	119	=item async { ... } [@args...]
38		120
39	package Coro;	121	Create a new asynchronous process and return it's process object
		122	(usually unused). When the sub returns the new process is automatically
		123	terminated.
40		124
41	BEGIN {	125	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	126	async {
		127	print "@_\n";
		128	} 1,2,3,4;
43		129
44	require XSLoader;	130	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	131	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		132
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	133	=cut
		134
		135	sub async(&@) {
		136	my $pid = new Coro @_;
		137	$pid->ready;
		138	$pid;
		139	}
		140
		141	=item schedule
		142
		143	Calls the scheduler. Please note that the current process will not be put
		144	into the ready queue, so calling this function usually means you will
		145	never be called again.
		146
		147	=cut
		148
		149	my $prev;
		150
		151	sub schedule {
		152	# should be done using priorities :(
		153	($prev, $current) = ($current, shift @ready \|\| $idle);
		154	Coro::State::transfer($prev, $current);
		155	}
		156
		157	=item cede
		158
		159	"Cede" to other processes. This function puts the current process into the
		160	ready queue and calls C<schedule>, which has the effect of giving up the
		161	current "timeslice" to other coroutines of the same or higher priority.
		162
		163	=cut
		164
		165	sub cede {
		166	$current->ready;
		167	&schedule;
		168	}
		169
		170	=item terminate
		171
		172	Terminates the current process.
		173
		174	Future versions of this function will allow result arguments.
		175
		176	=cut
		177
		178	# this coroutine is necessary because a coroutine
		179	# cannot destroy itself.
		180	my @destroy;
		181	my $terminate = new Coro sub {
		182	while() {
		183	delete ((pop @destroy)->{_coro_state}) while @destroy;
		184	&schedule;
		185	}
		186	};
		187
		188	sub terminate {
		189	push @destroy, $current;
		190	$terminate->ready;
		191	&schedule;
		192	# NORETURN
		193	}
		194
		195	=back
		196
		197	# dynamic methods
		198
		199	=head2 PROCESS METHODS
		200
		201	These are the methods you can call on process objects.
		202
		203	=over 4
		204
		205	=item new Coro \&sub [, @args...]
		206
		207	Create a new process and return it. When the sub returns the process
		208	automatically terminates. To start the process you must first put it into
		209	the ready queue by calling the ready method.
		210
		211	The coderef you submit MUST NOT be a closure that refers to variables
		212	in an outer scope. This does NOT work. Pass arguments into it instead.
		213
		214	=cut
		215
		216	sub _newcoro {
		217	terminate &{+shift};
		218	}
59		219
60	sub new {	220	sub new {
61	my $class = $_[0];	221	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	222	bless {
63	bless _newprocess {	223	_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;	224	}, $class;
73	}	225	}
74		226
75	=item $prev->transfer($next)	227	=item $process->ready
76		228
77	Save the state of the current subroutine in C<$prev> and switch to the	229	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		230
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	231	=cut
96		232
97	# I call the _transfer function from a perl function	233	sub ready {
98	# because that way perl saves all important things on	234	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	}	235	}
104		236
105	=item $error, $error_msg, $error_coro	237	=back
106		238
107	This coroutine will be called on fatal errors. C<$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	239	=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		240
121	1;	241	1;
122		242
123	=back	243	=head1 BUGS/LIMITATIONS
124		244
125	=head1 BUGS	245	- could be faster, especially when the core would introduce special
126		246	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	247	- there is still a memleak on coroutine termination that I could not
		248	identify. Could be as small as a single SV.
		249	- this module is not well-tested.
		250	- if variables or arguments "disappear" (become undef) or become
		251	corrupted please contact the author so he cen iron out the
		252	remaining bugs.
		253	- this module is not thread-safe. You must only ever use this module from
		254	the same thread (this requirement might be loosened in the future to
		255	allow per-thread schedulers, but Coro::State does not yet allow this).
128		256
129	=head1 SEE ALSO	257	=head1 SEE ALSO
130		258
131	L<Coro::Process>, L<Coro::Signal>.	259	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		260	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
132		261
133	=head1 AUTHOR	262	=head1 AUTHOR
134		263
135	Marc Lehmann <pcg@goof.com>	264	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	265	http://www.goof.com/pcg/marc/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs. Revision 1.23 by root, Mon Jul 23 04:23:32 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 1.23 by root, Mon Jul 23 04:23:32 2001 UTC