[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 1.29 by root, Sat Aug 11 00:37:31 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	# we really need priorities...
		124	my @ready; # the ready queue. hehe, rather broken ;)
		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	my $prev;
		166
		167	sub schedule {
		168	# should be done using priorities :(
		169	($prev, $current) = ($current, shift @ready \|\| $idle);
		170	Coro::State::transfer($prev, $current);
		171	}
		172
		173	=item cede
		174
		175	"Cede" to other processes. This function puts the current process into the
		176	ready queue and calls C<schedule>, which has the effect of giving up the
		177	current "timeslice" to other coroutines of the same or higher priority.
		178
		179	=cut
		180
		181	sub cede {
		182	$current->ready;
		183	&schedule;
		184	}
		185
		186	=item terminate
		187
		188	Terminates the current process.
		189
		190	Future versions of this function will allow result arguments.
		191
		192	=cut
		193
		194	sub terminate {
		195	$current->cancel;
		196	&schedule;
		197	die; # NORETURN
		198	}
		199
		200	=back
		201
		202	# dynamic methods
		203
		204	=head2 PROCESS METHODS
		205
		206	These are the methods you can call on process objects.
		207
		208	=over 4
		209
		210	=item new Coro \&sub [, @args...]
		211
		212	Create a new process and return it. When the sub returns the process
		213	automatically terminates. To start the process you must first put it into
		214	the ready queue by calling the ready method.
		215
		216	The coderef you submit MUST NOT be a closure that refers to variables
		217	in an outer scope. This does NOT work. Pass arguments into it instead.
		218
		219	=cut
		220
		221	sub _newcoro {
		222	terminate &{+shift};
		223	}
59		224
60	sub new {	225	sub new {
61	my $class = $_[0];	226	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	227	bless {
63	bless _newprocess {	228	_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;	229	}, $class;
73	}	230	}
74		231
75	=item $prev->transfer($next)	232	=item $process->ready
76		233
77	Save the state of the current subroutine in C<$prev> and switch to the	234	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		235
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	236	=cut
96		237
97	# I call the _transfer function from a perl function	238	sub ready {
98	# because that way perl saves all important things on	239	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	}	240	}
104		241
105	=item $error, $error_msg, $error_coro	242	=item $process->cancel
106		243
107	This coroutine will be called on fatal errors. C<$error_msg> and	244	Like C<terminate>, but terminates the specified process instead.
108	C<$error_coro> return the error message and the error-causing coroutine
109	(NOT an object) respectively. This API might change.
110		245
111	=cut	246	=cut
112		247
113	$error_msg =	248	sub cancel {
114	$error_coro = undef;	249	push @destroy, $_[0];
		250	$manager->ready;
		251	}
115		252
116	$error = _newprocess {	253	=back
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	254
118	exit 50;	255	=cut
119	};
120		256
121	1;	257	1;
122		258
123	=back	259	=head1 BUGS/LIMITATIONS
124		260
125	=head1 BUGS	261	- could be faster, especially when the core would introduce special
126		262	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	263	- there is still a memleak on coroutine termination that I could not
		264	identify. Could be as small as a single SV.
		265	- this module is not well-tested.
		266	- if variables or arguments "disappear" (become undef) or become
		267	corrupted please contact the author so he cen iron out the
		268	remaining bugs.
		269	- this module is not thread-safe. You must only ever use this module from
		270	the same thread (this requirement might be loosened in the future to
		271	allow per-thread schedulers, but Coro::State does not yet allow this).
128		272
129	=head1 SEE ALSO	273	=head1 SEE ALSO
130		274
131	L<Coro::Process>, L<Coro::Signal>.	275	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		276	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		277	L<Coro::Handle>, L<Coro::Socket>.
132		278
133	=head1 AUTHOR	279	=head1 AUTHOR
134		280
135	Marc Lehmann <pcg@goof.com>	281	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	282	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 1.29 by root, Sat Aug 11 00:37:31 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 1.29 by root, Sat Aug 11 00:37:31 2001 UTC