[ViewVC] Diff of: cvs/Coro/Coro.pm

Comparing Coro/Coro.pm (file contents):
Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.57 by pcg, Sun Nov 30 22:49:25 2003 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	In this module, coroutines are defined as "callchain + lexical variables
32	low-level functionality. See L<Coro::Process> and related modules for a	27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
33	more useful process abstraction including scheduling.	28	callchain, it's own set of lexicals and it's own set of perl's most
		29	important global variables.
		30
		31	=cut
		32
		33	package Coro;
		34
		35	BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") }
		36
		37	use Coro::State;
		38
		39	use vars qw($idle $main $current);
		40
		41	use base Exporter;
		42
		43	$VERSION = "0.9";
		44
		45	@EXPORT = qw(async cede schedule terminate current);
		46	%EXPORT_TAGS = (
		47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		48	);
		49	@EXPORT_OK = @{$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	}
34		81
35	=over 4	82	=over 4
36		83
37	=cut	84	=item $main
38		85
39	package Coro;	86	This coroutine represents the main program.
40		87
41	BEGIN {
42	$VERSION = 0.03;
43
44	require XSLoader;
45	XSLoader::load Coro, $VERSION;
46	}
47
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	88	=cut
		89
		90	$main = new Coro;
		91
		92	=item $current (or as function: current)
		93
		94	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		95
		96	=cut
		97
		98	# maybe some other module used Coro::Specific before...
		99	if ($current) {
		100	$main->{specific} = $current->{specific};
		101	}
		102
		103	$current = $main;
		104
		105	sub current() { $current }
		106
		107	=item $idle
		108
		109	The coroutine to switch to when no other coroutine is running. The default
		110	implementation prints "FATAL: deadlock detected" and exits.
		111
		112	=cut
		113
		114	# should be done using priorities :(
		115	$idle = new Coro sub {
		116	print STDERR "FATAL: deadlock detected\n";
		117	exit(51);
		118	};
		119
		120	# this coroutine is necessary because a coroutine
		121	# cannot destroy itself.
		122	my @destroy;
		123	my $manager;
		124	$manager = new Coro sub {
		125	while () {
		126	# by overwriting the state object with the manager we destroy it
		127	# while still being able to schedule this coroutine (in case it has
		128	# been readied multiple times. this is harmless since the manager
		129	# can be called as many times as neccessary and will always
		130	# remove itself from the runqueue
		131	while (@destroy) {
		132	my $coro = pop @destroy;
		133	$coro->{status} \|\|= [];
		134	$_->ready for @{delete $coro->{join} \|\| []};
		135	$coro->{_coro_state} = $manager->{_coro_state};
		136	}
		137	&schedule;
		138	}
		139	};
		140
		141	# static methods. not really.
		142
		143	=back
		144
		145	=head2 STATIC METHODS
		146
		147	Static methods are actually functions that operate on the current process only.
		148
		149	=over 4
		150
		151	=item async { ... } [@args...]
		152
		153	Create a new asynchronous process and return it's process object
		154	(usually unused). When the sub returns the new process is automatically
		155	terminated.
		156
		157	# create a new coroutine that just prints its arguments
		158	async {
		159	print "@_\n";
		160	} 1,2,3,4;
		161
		162	=cut
		163
		164	sub async(&@) {
		165	my $pid = new Coro @_;
		166	$manager->ready; # this ensures that the stack is cloned from the manager
		167	$pid->ready;
		168	$pid;
		169	}
		170
		171	=item schedule
		172
		173	Calls the scheduler. Please note that the current process will not be put
		174	into the ready queue, so calling this function usually means you will
		175	never be called again.
		176
		177	=cut
		178
		179	=item cede
		180
		181	"Cede" to other processes. This function puts the current process into the
		182	ready queue and calls C<schedule>, which has the effect of giving up the
		183	current "timeslice" to other coroutines of the same or higher priority.
		184
		185	=cut
		186
		187	=item terminate [arg...]
		188
		189	Terminates the current process.
		190
		191	Future versions of this function will allow result arguments.
		192
		193	=cut
		194
		195	sub terminate {
		196	$current->{status} = [@_];
		197	$current->cancel;
		198	&schedule;
		199	die; # NORETURN
		200	}
		201
		202	=back
		203
		204	# dynamic methods
		205
		206	=head2 PROCESS METHODS
		207
		208	These are the methods you can call on process objects.
		209
		210	=over 4
		211
		212	=item new Coro \&sub [, @args...]
		213
		214	Create a new process and return it. When the sub returns the process
		215	automatically terminates as if C<terminate> with the returned values were
		216	called. To make the process run you must first put it into the ready queue
		217	by calling the ready method.
		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 $prev and switch to the	234	Put the given process into the ready queue.
78	coroutine saved in $next.
79		235
80	=cut	236	=cut
81		237
82	# I call the _transfer function from a perl function	238	=item $process->cancel
83	# because that way perl saves all important things on
84	# the stack.
85	sub transfer {
86	_transfer($_[0], $_[1]);
87	}
88		239
89	=item $error, $error_msg, $error_coro	240	Like C<terminate>, but terminates the specified process instead.
90		241
91	This coroutine will be called on fatal errors. C<$error_msg> and
92	C<$error_coro> return the error message and the error-causing coroutine
93	(NOT an object) respectively. This API might change.
94
95	=cut	242	=cut
96		243
97	$error_msg =	244	sub cancel {
98	$error_coro = undef;	245	push @destroy, $_[0];
		246	$manager->ready;
		247	&schedule if $current == $_[0];
		248	}
99		249
100	$error = _newprocess {	250	=item $process->join
101	print STDERR "FATAL: $error_msg\nprogram aborted\n";	251
102	exit 50;	252	Wait until the coroutine terminates and return any values given to the
103	};	253	C<terminate> function. C<join> can be called multiple times from multiple
		254	processes.
		255
		256	=cut
		257
		258	sub join {
		259	my $self = shift;
		260	unless ($self->{status}) {
		261	push @{$self->{join}}, $current;
		262	&schedule;
		263	}
		264	wantarray ? @{$self->{status}} : $self->{status}[0];
		265	}
		266
		267	=item $oldprio = $process->prio($newprio)
		268
		269	Sets (or gets, if the argument is missing) the priority of the
		270	process. Higher priority processes get run before lower priority
		271	processes. Priorities are small signed integers (currently -4 .. +3),
		272	that you can refer to using PRIO_xxx constants (use the import tag :prio
		273	to get then):
		274
		275	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		276	3 > 1 > 0 > -1 > -3 > -4
		277
		278	# set priority to HIGH
		279	current->prio(PRIO_HIGH);
		280
		281	The idle coroutine ($Coro::idle) always has a lower priority than any
		282	existing coroutine.
		283
		284	Changing the priority of the current process will take effect immediately,
		285	but changing the priority of processes in the ready queue (but not
		286	running) will only take effect after the next schedule (of that
		287	process). This is a bug that will be fixed in some future version.
		288
		289	=cut
		290
		291	sub prio {
		292	my $old = $_[0]{prio};
		293	$_[0]{prio} = $_[1] if @_ > 1;
		294	$old;
		295	}
		296
		297	=item $newprio = $process->nice($change)
		298
		299	Similar to C<prio>, but subtract the given value from the priority (i.e.
		300	higher values mean lower priority, just as in unix).
		301
		302	=cut
		303
		304	sub nice {
		305	$_[0]{prio} -= $_[1];
		306	}
		307
		308	=item $olddesc = $process->desc($newdesc)
		309
		310	Sets (or gets in case the argument is missing) the description for this
		311	process. This is just a free-form string you can associate with a process.
		312
		313	=cut
		314
		315	sub desc {
		316	my $old = $_[0]{desc};
		317	$_[0]{desc} = $_[1] if @_ > 1;
		318	$old;
		319	}
		320
		321	=back
		322
		323	=cut
104		324
105	1;	325	1;
106		326
107	=back	327	=head1 BUGS/LIMITATIONS
108		328
109	=head1 BUGS	329	- you must make very sure that no coro is still active on global
		330	destruction. very bad things might happen otherwise (usually segfaults).
110		331
111	This module has not yet been extensively tested.	332	- this module is not thread-safe. You should only ever use this module
		333	from the same thread (this requirement might be losened in the future
		334	to allow per-thread schedulers, but Coro::State does not yet allow
		335	this).
112		336
113	=head1 SEE ALSO	337	=head1 SEE ALSO
114		338
115	L<Coro::Process>, L<Coro::Signal>.	339	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		340	L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>,
		341	L<Coro::L<Coro::RWLock>, Handle>, L<Coro::Socket>.
116		342
117	=head1 AUTHOR	343	=head1 AUTHOR
118		344
119	Marc Lehmann <pcg@goof.com>	345	Marc Lehmann <pcg@goof.com>
120	http://www.goof.com/pcg/marc/	346	http://www.goof.com/pcg/marc/

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Comparing Coro/Coro.pm (file contents): Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs. Revision 1.57 by pcg, Sun Nov 30 22:49:25 2003 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.57 by pcg, Sun Nov 30 22:49:25 2003 UTC