[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 1.22 by root, Mon Jul 23 02:14:19 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), that is, a coroutine has it's own callchain, it's
		30	own set of lexicals and it's own set of perl's most important global
		31	variables.
		32
		33	WARNING: When using this module, make sure that, at program end, no
		34	coroutines are still running OR just call exit before falling off the
		35	end. The reason for this is that some coroutine of yours might have called
		36	into a C function, and falling off the end of main:: results in returning
		37	to that C function instead if to the main C interpreter.
		38
		39	WARNING: Unless you really know what you are doing, do NOT do context
		40	switches inside callbacks from the XS level. The reason for this is
		41	similar to the reason above: A callback calls a perl function, this
		42	perl function does a context switch, some other callback is called, the
		43	original function returns from it - to what? To the wrong XS function,
		44	with totally different return values. Unfortunately, this includes
		45	callbacks done by perl itself (tie'd variables!).
		46
		47	The only workaround for this is to do coroutines on C level.
		48
		49	=cut
		50
		51	package Coro;
		52
		53	use Coro::State;
		54
		55	use base Exporter;
		56
		57	$VERSION = 0.10;
		58
		59	@EXPORT = qw(async cede schedule terminate current);
		60	@EXPORT_OK = qw($current);
		61
		62	{
		63	my @async;
		64
		65	# this way of handling attributes simply is NOT scalable ;()
		66	sub import {
		67	Coro->export_to_level(1, @_);
		68	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		69	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		70	my ($package, $ref) = (shift, shift);
		71	my @attrs;
		72	for (@_) {
		73	if ($_ eq "Coro") {
		74	push @async, $ref;
		75	} else {
		76	push @attrs, $_;
		77	}
		78	}
		79	return $old ? $old->($package, $ref, @attrs) : @attrs;
		80	};
		81	}
		82
		83	sub INIT {
		84	&async(pop @async) while @async;
		85	}
		86	}
		87
		88	=item $main
		89
		90	This coroutine represents the main program.
		91
		92	=cut
		93
		94	our $main = new Coro;
		95
		96	=item $current (or as function: current)
		97
		98	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		99
		100	=cut
		101
		102	# maybe some other module used Coro::Specific before...
		103	if ($current) {
		104	$main->{specific} = $current->{specific};
		105	}
		106
		107	our $current = $main;
		108
		109	sub current() { $current }
		110
		111	=item $idle
		112
		113	The coroutine to switch to when no other coroutine is running. The default
		114	implementation prints "FATAL: deadlock detected" and exits.
		115
		116	=cut
		117
		118	# should be done using priorities :(
		119	our $idle = new Coro sub {
		120	print STDERR "FATAL: deadlock detected\n";
		121	exit(51);
		122	};
		123
		124	# we really need priorities...
		125	my @ready; # the ready queue. hehe, rather broken ;)
		126
		127	# static methods. not really.
		128
		129	=head2 STATIC METHODS
		130
		131	Static methods are actually functions that operate on the current process only.
34		132
35	=over 4	133	=over 4
36		134
37	=cut	135	=item async { ... } [@args...]
38		136
39	package Coro;	137	Create a new asynchronous process and return it's process object
		138	(usually unused). When the sub returns the new process is automatically
		139	terminated.
40		140
41	BEGIN {	141	# create a new coroutine that just prints its arguments
42	$VERSION = 0.03;	142	async {
		143	print "@_\n";
		144	} 1,2,3,4;
43		145
44	require XSLoader;	146	The coderef you submit MUST NOT be a closure that refers to variables
45	XSLoader::load Coro, $VERSION;	147	in an outer scope. This does NOT work. Pass arguments into it instead.
46	}
47		148
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	149	=cut
		150
		151	sub async(&@) {
		152	my $pid = new Coro @_;
		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	my $self = $current;
		196	$self->{_results} = [@_];
		197	$current = shift @ready \|\| $idle;
		198	Coro::State::transfer(delete $self->{_coro_state}, $current);
		199	# cannot return
		200	die;
		201	}
		202
		203	=back
		204
		205	# dynamic methods
		206
		207	=head2 PROCESS METHODS
		208
		209	These are the methods you can call on process objects.
		210
		211	=over 4
		212
		213	=item new Coro \&sub [, @args...]
		214
		215	Create a new process and return it. When the sub returns the process
		216	automatically terminates. To start the process you must first put it into
		217	the ready queue by calling the ready method.
		218
		219	The coderef you submit MUST NOT be a closure that refers to variables
		220	in an outer scope. This does NOT work. Pass arguments into it instead.
		221
		222	=cut
		223
		224	sub _newcoro {
		225	terminate &{+shift};
		226	}
59		227
60	sub new {	228	sub new {
61	my $class = $_[0];	229	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	230	bless {
63	bless _newprocess {	231	_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;	232	}, $class;
73	}	233	}
74		234
75	=item $prev->transfer($next)	235	=item $process->ready
76		236
77	Save the state of the current subroutine in C<$prev> and switch to the	237	Put the current process into the ready queue.
78	coroutine saved in C<$next>.
79		238
80	The "state" of a subroutine only ever includes scope, i.e. lexical
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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	239	=cut
96		240
97	# I call the _transfer function from a perl function	241	sub ready {
98	# because that way perl saves all important things on	242	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	}	243	}
104		244
105	=item $error, $error_msg, $error_coro	245	=back
106		246
107	This coroutine will be called on fatal errors. C<$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	247	=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		248
121	1;	249	1;
122		250
123	=back	251	=head1 BUGS/LIMITATIONS
124		252
125	=head1 BUGS	253	- could be faster, especially when the core would introduce special
126		254	support for coroutines (like it does for threads).
127	This module has not yet been extensively tested.	255	- there is still a memleak on coroutine termination that I could not
		256	identify. Could be as small as a single SV.
		257	- this module is not well-tested.
		258	- if variables or arguments "disappear" (become undef) or become
		259	corrupted please contact the author so he cen iron out the
		260	remaining bugs.
		261	- this module is not thread-safe. You must only ever use this module from
		262	the same thread (this requirement might be loosened in the future to
		263	allow per-thread schedulers, but Coro::State does not yet allow this).
128		264
129	=head1 SEE ALSO	265	=head1 SEE ALSO
130		266
131	L<Coro::Process>, L<Coro::Signal>.	267	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		268	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
132		269
133	=head1 AUTHOR	270	=head1 AUTHOR
134		271
135	Marc Lehmann <pcg@goof.com>	272	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	273	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 1.22 by root, Mon Jul 23 02:14:19 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 1.22 by root, Mon Jul 23 02:14:19 2001 UTC