[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 1.73 by root, Mon Dec 12 20:31:23 2005 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	use strict;
		36	no warnings "uninitialized";
		37
		38	use Coro::State;
		39
		40	use base Exporter::;
		41
		42	our $idle; # idle coroutine
		43	our $main; # main coroutine
		44	our $current; # current coroutine
		45
		46	our $VERSION = 1.6;
		47
		48	our @EXPORT = qw(async cede schedule terminate current);
		49	our %EXPORT_TAGS = (
		50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		51	);
		52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};
		53
		54	{
		55	my @async;
		56	my $init;
		57
		58	# this way of handling attributes simply is NOT scalable ;()
		59	sub import {
		60	no strict 'refs';
		61
		62	Coro->export_to_level(1, @_);
		63
		64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		66	my ($package, $ref) = (shift, shift);
		67	my @attrs;
		68	for (@_) {
		69	if ($_ eq "Coro") {
		70	push @async, $ref;
		71	unless ($init++) {
		72	eval q{
		73	sub INIT {
		74	&async(pop @async) while @async;
		75	}
		76	};
		77	}
		78	} else {
		79	push @attrs, $_;
		80	}
		81	}
		82	return $old ? $old->($package, $ref, @attrs) : @attrs;
		83	};
		84	}
		85
		86	}
34		87
35	=over 4	88	=over 4
36		89
37	=cut	90	=item $main
38		91
39	package Coro;	92	This coroutine represents the main program.
40		93
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	94	=cut
		95
		96	$main = new Coro;
		97
		98	=item $current (or as function: current)
		99
		100	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
		101
		102	=cut
		103
		104	# maybe some other module used Coro::Specific before...
		105	if ($current) {
		106	$main->{specific} = $current->{specific};
		107	}
		108
		109	$current = $main;
		110
		111	sub current() { $current }
		112
		113	=item $idle
		114
		115	The coroutine to switch to when no other coroutine is running. The default
		116	implementation prints "FATAL: deadlock detected" and exits.
		117
		118	=cut
		119
		120	# should be done using priorities :(
		121	$idle = new Coro sub {
		122	print STDERR "FATAL: deadlock detected\n";
		123	exit(51);
		124	};
		125
		126	# this coroutine is necessary because a coroutine
		127	# cannot destroy itself.
		128	my @destroy;
		129	my $manager;
		130	$manager = new Coro sub {
		131	while () {
		132	# by overwriting the state object with the manager we destroy it
		133	# while still being able to schedule this coroutine (in case it has
		134	# been readied multiple times. this is harmless since the manager
		135	# can be called as many times as neccessary and will always
		136	# remove itself from the runqueue
		137	while (@destroy) {
		138	my $coro = pop @destroy;
		139	$coro->{status} \|\|= [];
		140	$_->ready for @{delete $coro->{join} \|\| []};
		141
		142	# the next line destroys the _coro_state, but keeps the
		143	# process itself intact (we basically make it a zombie
		144	# process that always runs the manager thread, so it's possible
		145	# to transfer() to this process).
		146	$coro->{_coro_state} = $manager->{_coro_state};
		147	}
		148	&schedule;
		149	}
		150	};
		151
		152	# static methods. not really.
		153
		154	=back
		155
		156	=head2 STATIC METHODS
		157
		158	Static methods are actually functions that operate on the current process only.
		159
		160	=over 4
		161
		162	=item async { ... } [@args...]
		163
		164	Create a new asynchronous process and return it's process object
		165	(usually unused). When the sub returns the new process is automatically
		166	terminated.
		167
		168	# create a new coroutine that just prints its arguments
		169	async {
		170	print "@_\n";
		171	} 1,2,3,4;
		172
		173	=cut
		174
		175	sub async(&@) {
		176	my $pid = new Coro @_;
		177	$manager->ready; # this ensures that the stack is cloned from the manager
		178	$pid->ready;
		179	$pid;
		180	}
		181
		182	=item schedule
		183
		184	Calls the scheduler. Please note that the current process will not be put
		185	into the ready queue, so calling this function usually means you will
		186	never be called again.
		187
		188	=cut
		189
		190	=item cede
		191
		192	"Cede" to other processes. This function puts the current process into the
		193	ready queue and calls C<schedule>, which has the effect of giving up the
		194	current "timeslice" to other coroutines of the same or higher priority.
		195
		196	=cut
		197
		198	=item terminate [arg...]
		199
		200	Terminates the current process with the given status values (see L<cancel>).
		201
		202	=cut
		203
		204	sub terminate {
		205	$current->cancel (@_);
		206	}
		207
		208	=back
		209
		210	# dynamic methods
		211
		212	=head2 PROCESS METHODS
		213
		214	These are the methods you can call on process objects.
		215
		216	=over 4
		217
		218	=item new Coro \&sub [, @args...]
		219
		220	Create a new process and return it. When the sub returns the process
		221	automatically terminates as if C<terminate> with the returned values were
		222	called. To make the process run you must first put it into the ready queue
		223	by calling the ready method.
		224
		225	=cut
		226
		227	sub _newcoro {
		228	terminate &{+shift};
		229	}
59		230
60	sub new {	231	sub new {
61	my $class = $_[0];	232	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	233	bless {
63	bless _newprocess {	234	_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;	235	}, $class;
73	}	236	}
74		237
75	=item $prev->transfer($next)	238	=item $process->ready
76		239
77	Save the state of the current subroutine in C<$prev> and switch to the	240	Put the given process into the ready queue.
78	coroutine saved in C<$next>.
79		241
80	The "state" of a subroutine only ever includes scope, i.e. lexical	242	=cut
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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		243
88	The easiest way to do this is to create your own scheduling primitive like this:	244	=item $process->cancel (arg...)
89		245
90	sub schedule {	246	Temrinates the given process and makes it return the given arguments as
91	local ($_, $@, ...);	247	status (default: the empty list).
92	$old->transfer($new);	248
		249	=cut
		250
		251	sub cancel {
		252	my $self = shift;
		253	$self->{status} = [@_];
		254	push @destroy, $self;
		255	$manager->ready;
		256	&schedule if $current == $self;
		257	}
		258
		259	=item $process->join
		260
		261	Wait until the coroutine terminates and return any values given to the
		262	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		263	from multiple processes.
		264
		265	=cut
		266
		267	sub join {
		268	my $self = shift;
		269	unless ($self->{status}) {
		270	push @{$self->{join}}, $current;
		271	&schedule;
93	}	272	}
94		273	wantarray ? @{$self->{status}} : $self->{status}[0];
95	=cut
96
97	# I call the _transfer function from a perl function
98	# because that way perl saves all important things on
99	# the stack. Actually, I'd do it from within XS, but
100	# I couldn't get it to work.
101	sub transfer {
102	_transfer($_[0], $_[1]);
103	}	274	}
104		275
105	=item $error, $error_msg, $error_coro	276	=item $oldprio = $process->prio($newprio)
106		277
107	This coroutine will be called on fatal errors. C<$error_msg> and	278	Sets (or gets, if the argument is missing) the priority of the
108	C<$error_coro> return the error message and the error-causing coroutine	279	process. Higher priority processes get run before lower priority
109	(NOT an object) respectively. This API might change.	280	processes. Priorities are small signed integers (currently -4 .. +3),
		281	that you can refer to using PRIO_xxx constants (use the import tag :prio
		282	to get then):
110		283
111	=cut	284	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		285	3 > 1 > 0 > -1 > -3 > -4
112		286
113	$error_msg =	287	# set priority to HIGH
114	$error_coro = undef;	288	current->prio(PRIO_HIGH);
115		289
116	$error = _newprocess {	290	The idle coroutine ($Coro::idle) always has a lower priority than any
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	291	existing coroutine.
118	exit 50;	292
119	};	293	Changing the priority of the current process will take effect immediately,
		294	but changing the priority of processes in the ready queue (but not
		295	running) will only take effect after the next schedule (of that
		296	process). This is a bug that will be fixed in some future version.
		297
		298	=cut
		299
		300	sub prio {
		301	my $old = $_[0]{prio};
		302	$_[0]{prio} = $_[1] if @_ > 1;
		303	$old;
		304	}
		305
		306	=item $newprio = $process->nice($change)
		307
		308	Similar to C<prio>, but subtract the given value from the priority (i.e.
		309	higher values mean lower priority, just as in unix).
		310
		311	=cut
		312
		313	sub nice {
		314	$_[0]{prio} -= $_[1];
		315	}
		316
		317	=item $olddesc = $process->desc($newdesc)
		318
		319	Sets (or gets in case the argument is missing) the description for this
		320	process. This is just a free-form string you can associate with a process.
		321
		322	=cut
		323
		324	sub desc {
		325	my $old = $_[0]{desc};
		326	$_[0]{desc} = $_[1] if @_ > 1;
		327	$old;
		328	}
		329
		330	=back
		331
		332	=cut
120		333
121	1;	334	1;
122		335
123	=back	336	=head1 BUGS/LIMITATIONS
124		337
125	=head1 BUGS	338	- you must make very sure that no coro is still active on global
		339	destruction. very bad things might happen otherwise (usually segfaults).
126		340
127	This module has not yet been extensively tested.	341	- this module is not thread-safe. You should only ever use this module
		342	from the same thread (this requirement might be losened in the future
		343	to allow per-thread schedulers, but Coro::State does not yet allow
		344	this).
128		345
129	=head1 SEE ALSO	346	=head1 SEE ALSO
130		347
131	L<Coro::Process>, L<Coro::Signal>.	348	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		349
		350	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		351
		352	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		353
		354	Embedding: L<Coro:MakeMaker>
132		355
133	=head1 AUTHOR	356	=head1 AUTHOR
134		357
135	Marc Lehmann <pcg@goof.com>	358	Marc Lehmann <schmorp@schmorp.de>
136	http://www.goof.com/pcg/marc/	359	http://home.schmorp.de/
137		360
138	=cut	361	=cut
139		362

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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 1.73 by root, Mon Dec 12 20:31:23 2005 UTC

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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 1.73 by root, Mon Dec 12 20:31:23 2005 UTC