[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 1.30 by root, Sat Aug 11 19:59:19 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	$VERSION = 0.45;
		42
		43	@EXPORT = qw(async cede schedule terminate current);
		44	@EXPORT_OK = qw($current);
		45
		46	{
		47	my @async;
		48	my $init;
		49
		50	# this way of handling attributes simply is NOT scalable ;()
		51	sub import {
		52	Coro->export_to_level(1, @_);
		53	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		54	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		55	my ($package, $ref) = (shift, shift);
		56	my @attrs;
		57	for (@_) {
		58	if ($_ eq "Coro") {
		59	push @async, $ref;
		60	unless ($init++) {
		61	eval q{
		62	sub INIT {
		63	&async(pop @async) while @async;
		64	}
		65	};
		66	}
		67	} else {
		68	push @attrs, $_;
		69	}
		70	}
		71	return $old ? $old->($package, $ref, @attrs) : @attrs;
		72	};
		73	}
		74
		75	}
		76
		77	=item $main
		78
		79	This coroutine represents the main program.
		80
		81	=cut
		82
		83	our $main = new Coro;
		84
		85	=item $current (or as function: current)
		86
		87	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		88
		89	=cut
		90
		91	# maybe some other module used Coro::Specific before...
		92	if ($current) {
		93	$main->{specific} = $current->{specific};
		94	}
		95
		96	our $current = $main;
		97
		98	sub current() { $current }
		99
		100	=item $idle
		101
		102	The coroutine to switch to when no other coroutine is running. The default
		103	implementation prints "FATAL: deadlock detected" and exits.
		104
		105	=cut
		106
		107	# should be done using priorities :(
		108	our $idle = new Coro sub {
		109	print STDERR "FATAL: deadlock detected\n";
		110	exit(51);
		111	};
		112
		113	# this coroutine is necessary because a coroutine
		114	# cannot destroy itself.
		115	my @destroy;
		116	my $manager = new Coro sub {
		117	while() {
		118	delete ((pop @destroy)->{_coro_state}) while @destroy;
		119	&schedule;
		120	}
		121	};
		122
		123	# static methods. not really.
		124
		125	=head2 STATIC METHODS
		126
		127	Static methods are actually functions that operate on the current process only.
34		128
35	=over 4	129	=over 4
36		130
37	=cut	131	=item async { ... } [@args...]
38		132
39	package Coro;	133	Create a new asynchronous process and return it's process object
		134	(usually unused). When the sub returns the new process is automatically
		135	terminated.
40		136
41	BEGIN {	137	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	138	async {
		139	print "@_\n";
		140	} 1,2,3,4;
43		141
44	require XSLoader;	142	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	143	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		144
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	145	=cut
		146
		147	sub async(&@) {
		148	my $pid = new Coro @_;
		149	$manager->ready; # this ensures that the stack is cloned from the manager
		150	$pid->ready;
		151	$pid;
		152	}
		153
		154	=item schedule
		155
		156	Calls the scheduler. Please note that the current process will not be put
		157	into the ready queue, so calling this function usually means you will
		158	never be called again.
		159
		160	=cut
		161
		162	=item cede
		163
		164	"Cede" to other processes. This function puts the current process into the
		165	ready queue and calls C<schedule>, which has the effect of giving up the
		166	current "timeslice" to other coroutines of the same or higher priority.
		167
		168	=cut
		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	sub terminate {
		179	$current->cancel;
		180	&schedule;
		181	die; # NORETURN
		182	}
		183
		184	=back
		185
		186	# dynamic methods
		187
		188	=head2 PROCESS METHODS
		189
		190	These are the methods you can call on process objects.
		191
		192	=over 4
		193
		194	=item new Coro \&sub [, @args...]
		195
		196	Create a new process and return it. When the sub returns the process
		197	automatically terminates. To start the process you must first put it into
		198	the ready queue by calling the ready method.
		199
		200	The coderef you submit MUST NOT be a closure that refers to variables
		201	in an outer scope. This does NOT work. Pass arguments into it instead.
		202
		203	=cut
		204
		205	sub _newcoro {
		206	terminate &{+shift};
		207	}
59		208
60	sub new {	209	sub new {
61	my $class = $_[0];	210	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	211	bless {
63	bless _newprocess {	212	_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;	213	}, $class;
73	}	214	}
74		215
75	=item $prev->transfer($next)	216	=item $process->ready
76		217
77	Save the state of the current subroutine in C<$prev> and switch to the	218	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		219
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	220	=cut
96		221
97	# I call the _transfer function from a perl function	222	=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		223
105	=item $error, $error_msg, $error_coro	224	Like C<terminate>, but terminates the specified process instead.
106		225
107	This coroutine will be called on fatal errors. C<$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	226	=cut
112		227
113	$error_msg =	228	sub cancel {
114	$error_coro = undef;	229	push @destroy, $_[0];
		230	$manager->ready;
		231	}
115		232
116	$error = _newprocess {	233	=back
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	234
118	exit 50;	235	=cut
119	};
120		236
121	1;	237	1;
122		238
123	=back	239	=head1 BUGS/LIMITATIONS
124		240
125	=head1 BUGS	241	- could be faster, especially when the core would introduce special
126		242	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	243	- there is still a memleak on coroutine termination that I could not
		244	identify. Could be as small as a single SV.
		245	- this module is not well-tested.
		246	- if variables or arguments "disappear" (become undef) or become
		247	corrupted please contact the author so he cen iron out the
		248	remaining bugs.
		249	- this module is not thread-safe. You must only ever use this module from
		250	the same thread (this requirement might be loosened in the future to
		251	allow per-thread schedulers, but Coro::State does not yet allow this).
128		252
129	=head1 SEE ALSO	253	=head1 SEE ALSO
130		254
131	L<Coro::Process>, L<Coro::Signal>.	255	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		256	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		257	L<Coro::Handle>, L<Coro::Socket>.
132		258
133	=head1 AUTHOR	259	=head1 AUTHOR
134		260
135	Marc Lehmann <pcg@goof.com>	261	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	262	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 1.30 by root, Sat Aug 11 19:59:19 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 1.30 by root, Sat Aug 11 19:59:19 2001 UTC