[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 1.36 by root, Mon Sep 24 01:36:20 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	no warnings qw(uninitialized);
		38
		39	use Coro::State;
		40
		41	use base Exporter;
		42
		43	$VERSION = 0.5;
		44
		45	@EXPORT = qw(async cede schedule terminate current);
		46	%EXPORT_TAGS = (
		47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		48	);
		49	@EXPORT_OK = @{$EXPORT_TAGS{prio}};
		50
		51	{
		52	my @async;
		53	my $init;
		54
		55	# this way of handling attributes simply is NOT scalable ;()
		56	sub import {
		57	Coro->export_to_level(1, @_);
		58	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		59	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		60	my ($package, $ref) = (shift, shift);
		61	my @attrs;
		62	for (@_) {
		63	if ($_ eq "Coro") {
		64	push @async, $ref;
		65	unless ($init++) {
		66	eval q{
		67	sub INIT {
		68	&async(pop @async) while @async;
		69	}
		70	};
		71	}
		72	} else {
		73	push @attrs, $_;
		74	}
		75	}
		76	return $old ? $old->($package, $ref, @attrs) : @attrs;
		77	};
		78	}
		79
		80	}
		81
		82	=item $main
		83
		84	This coroutine represents the main program.
		85
		86	=cut
		87
		88	our $main = new Coro;
		89
		90	=item $current (or as function: current)
		91
		92	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		93
		94	=cut
		95
		96	# maybe some other module used Coro::Specific before...
		97	if ($current) {
		98	$main->{specific} = $current->{specific};
		99	}
		100
		101	our $current = $main;
		102
		103	sub current() { $current }
		104
		105	=item $idle
		106
		107	The coroutine to switch to when no other coroutine is running. The default
		108	implementation prints "FATAL: deadlock detected" and exits.
		109
		110	=cut
		111
		112	# should be done using priorities :(
		113	our $idle = new Coro sub {
		114	print STDERR "FATAL: deadlock detected\n";
		115	exit(51);
		116	};
		117
		118	# this coroutine is necessary because a coroutine
		119	# cannot destroy itself.
		120	my @destroy;
		121	my $manager = new Coro sub {
		122	while() {
		123	delete ((pop @destroy)->{_coro_state}) while @destroy;
		124	&schedule;
		125	}
		126	};
		127
		128	# static methods. not really.
		129
		130	=head2 STATIC METHODS
		131
		132	Static methods are actually functions that operate on the current process only.
34		133
35	=over 4	134	=over 4
36		135
37	=cut	136	=item async { ... } [@args...]
38		137
39	package Coro;	138	Create a new asynchronous process and return it's process object
		139	(usually unused). When the sub returns the new process is automatically
		140	terminated.
40		141
41	BEGIN {	142	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	143	async {
		144	print "@_\n";
		145	} 1,2,3,4;
43		146
44	require XSLoader;	147	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	148	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		149
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	150	=cut
		151
		152	sub async(&@) {
		153	my $pid = new Coro @_;
		154	$manager->ready; # this ensures that the stack is cloned from the manager
		155	$pid->ready;
		156	$pid;
		157	}
		158
		159	=item schedule
		160
		161	Calls the scheduler. Please note that the current process will not be put
		162	into the ready queue, so calling this function usually means you will
		163	never be called again.
		164
		165	=cut
		166
		167	=item cede
		168
		169	"Cede" to other processes. This function puts the current process into the
		170	ready queue and calls C<schedule>, which has the effect of giving up the
		171	current "timeslice" to other coroutines of the same or higher priority.
		172
		173	=cut
		174
		175	=item terminate
		176
		177	Terminates the current process.
		178
		179	Future versions of this function will allow result arguments.
		180
		181	=cut
		182
		183	sub terminate {
		184	$current->cancel;
		185	&schedule;
		186	die; # NORETURN
		187	}
		188
		189	=back
		190
		191	# dynamic methods
		192
		193	=head2 PROCESS METHODS
		194
		195	These are the methods you can call on process objects.
		196
		197	=over 4
		198
		199	=item new Coro \&sub [, @args...]
		200
		201	Create a new process and return it. When the sub returns the process
		202	automatically terminates. To start the process you must first put it into
		203	the ready queue by calling the ready method.
		204
		205	The coderef you submit MUST NOT be a closure that refers to variables
		206	in an outer scope. This does NOT work. Pass arguments into it instead.
		207
		208	=cut
		209
		210	sub _newcoro {
		211	terminate &{+shift};
		212	}
59		213
60	sub new {	214	sub new {
61	my $class = $_[0];	215	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	216	bless {
63	bless _newprocess {	217	_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;	218	}, $class;
73	}	219	}
74		220
75	=item $prev->transfer($next)	221	=item $process->ready
76		222
77	Save the state of the current subroutine in C<$prev> and switch to the	223	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		224
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	225	=cut
96		226
97	# I call the _transfer function from a perl function	227	=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		228
105	=item $error, $error_msg, $error_coro	229	Like C<terminate>, but terminates the specified process instead.
106		230
107	This coroutine will be called on fatal errors. C<$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	231	=cut
112		232
113	$error_msg =	233	sub cancel {
114	$error_coro = undef;	234	push @destroy, $_[0];
		235	$manager->ready;
		236	&schedule if $current == $_[0];
		237	}
115		238
116	$error = _newprocess {	239	=item $oldprio = $process->prio($newprio)
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	240
118	exit 50;	241	Sets the priority of the process. Higher priority processes get run before
119	};	242	lower priority processes. Priorities are smalled signed integer (currently
		243	-4 .. +3), that you can refer to using PRIO_xxx constants (use the import
		244	tag :prio to get then):
		245
		246	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		247	3 > 1 > 0 > -1 > -3 > -4
		248
		249	# set priority to HIGH
		250	current->prio(PRIO_HIGH);
		251
		252	The idle coroutine ($Coro::idle) always has a lower priority than any
		253	existing coroutine.
		254
		255	Changing the priority of the current process will take effect immediately,
		256	but changing the priority of processes in the ready queue (but not
		257	running) will only take effect after the next schedule (of that
		258	process). This is a bug that will be fixed in some future version.
		259
		260	=cut
		261
		262	sub prio {
		263	my $old = $_[0]{prio};
		264	$_[0]{prio} = $_[1] if @_ > 1;
		265	$old;
		266	}
		267
		268	=item $newprio = $process->nice($change)
		269
		270	Similar to C<prio>, but subtract the given value from the priority (i.e.
		271	higher values mean lower priority, just as in unix).
		272
		273	=cut
		274
		275	sub nice {
		276	$_[0]{prio} -= $_[1];
		277	}
		278
		279	=back
		280
		281	=cut
120		282
121	1;	283	1;
122		284
123	=back	285	=head1 BUGS/LIMITATIONS
124		286
125	=head1 BUGS	287	- you must make very sure that no coro is still active on global destruction.
126		288	very bad things might happen otherwise (usually segfaults).
127	This module has not yet been extensively tested.	289	- this module is not thread-safe. You must only ever use this module from
		290	the same thread (this requirement might be loosened in the future to
		291	allow per-thread schedulers, but Coro::State does not yet allow this).
128		292
129	=head1 SEE ALSO	293	=head1 SEE ALSO
130		294
131	L<Coro::Process>, L<Coro::Signal>.	295	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		296	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
		297	L<Coro::Handle>, L<Coro::Socket>.
132		298
133	=head1 AUTHOR	299	=head1 AUTHOR
134		300
135	Marc Lehmann <pcg@goof.com>	301	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	302	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 1.36 by root, Mon Sep 24 01:36:20 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 1.36 by root, Mon Sep 24 01:36:20 2001 UTC