[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 1.85 by root, Sat Nov 25 00:56:35 2006 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 qw(Coro::State Exporter);
		41
		42	our $idle; # idle handler
		43	our $main; # main coroutine
		44	our $current; # current coroutine
		45
		46	our $VERSION = '2.5';
		47
		48	our @EXPORT = qw(async cede schedule terminate current);
		49	our %EXPORT_TAGS = (
		50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		51	);
		52	our @EXPORT_OK = @{$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 $current (or as function: current)
		99
		100	The current coroutine (the last coroutine switched to). The initial value
		101	is C<$main> (of course).
		102
		103	This variable is B<strictly> I<read-only>. It is provided for performance
		104	reasons. If performance is not essentiel you are encouraged to use the
		105	C<Coro::current> function instead.
		106
		107	=cut
		108
		109	# maybe some other module used Coro::Specific before...
		110	if ($current) {
		111	$main->{specific} = $current->{specific};
		112	}
		113
		114	$current = $main;
		115
		116	sub current() { $current }
		117
		118	=item $idle
		119
		120	A callback that is called whenever the scheduler finds no ready coroutines
		121	to run. The default implementation prints "FATAL: deadlock detected" and
		122	exits.
		123
		124	This hook is overwritten by modules such as C<Coro::Timer> and
		125	C<Coro::Event> to wait on an external event that hopefully wakes up some
		126	coroutine.
		127
		128	=cut
		129
		130	$idle = sub {
		131	print STDERR "FATAL: deadlock detected\n";
		132	exit (51);
		133	};
		134
		135	# this coroutine is necessary because a coroutine
		136	# cannot destroy itself.
		137	my @destroy;
		138	my $manager;
		139	$manager = new Coro sub {
		140	while () {
		141	# by overwriting the state object with the manager we destroy it
		142	# while still being able to schedule this coroutine (in case it has
		143	# been readied multiple times. this is harmless since the manager
		144	# can be called as many times as neccessary and will always
		145	# remove itself from the runqueue
		146	while (@destroy) {
		147	my $coro = pop @destroy;
		148	$coro->{status} \|\|= [];
		149	$_->ready for @{delete $coro->{join} \|\| []};
		150
		151	# the next line destroys the coro state, but keeps the
		152	# process itself intact (we basically make it a zombie
		153	# process that always runs the manager thread, so it's possible
		154	# to transfer() to this process).
		155	$coro->_clone_state_from ($manager);
		156	}
		157	&schedule;
		158	}
		159	};
		160
		161	# static methods. not really.
		162
		163	=back
		164
		165	=head2 STATIC METHODS
		166
		167	Static methods are actually functions that operate on the current process only.
		168
		169	=over 4
		170
		171	=item async { ... } [@args...]
		172
		173	Create a new asynchronous process and return it's process object
		174	(usually unused). When the sub returns the new process is automatically
		175	terminated.
		176
		177	When the coroutine dies, the program will exit, just as in the main
		178	program.
		179
		180	# create a new coroutine that just prints its arguments
		181	async {
		182	print "@_\n";
		183	} 1,2,3,4;
		184
		185	=cut
		186
		187	sub async(&@) {
		188	my $pid = new Coro @_;
		189	$pid->ready;
		190	$pid
		191	}
		192
		193	=item schedule
		194
		195	Calls the scheduler. Please note that the current process will not be put
		196	into the ready queue, so calling this function usually means you will
		197	never be called again.
		198
		199	=cut
		200
		201	=item cede
		202
		203	"Cede" to other processes. This function puts the current process into the
		204	ready queue and calls C<schedule>, which has the effect of giving up the
		205	current "timeslice" to other coroutines of the same or higher priority.
		206
		207	=cut
		208
		209	=item terminate [arg...]
		210
		211	Terminates the current process with the given status values (see L<cancel>).
		212
		213	=cut
		214
		215	sub terminate {
		216	$current->cancel (@_);
		217	}
		218
		219	=back
		220
		221	# dynamic methods
		222
		223	=head2 PROCESS METHODS
		224
		225	These are the methods you can call on process objects.
		226
		227	=over 4
		228
		229	=item new Coro \&sub [, @args...]
		230
		231	Create a new process and return it. When the sub returns the process
		232	automatically terminates as if C<terminate> with the returned values were
		233	called. To make the process run you must first put it into the ready queue
		234	by calling the ready method.
		235
		236	=cut
		237
		238	sub _new_coro {
		239	$current->_clear_idle_sp; # set the idle sp on the following cede
		240	_set_cede_self; # ensures that cede cede's us first
		241	cede;
		242	terminate &{+shift};
		243	}
59		244
60	sub new {	245	sub new {
61	my $class = $_[0];	246	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };
63	bless _newprocess {
64	do {
65	eval { &$proc };
66	if ($@) {
67	$error_msg = $@;
68	$error_coro = _newprocess { };
69	&transfer($error_coro, $error);
70	}
71	} while (1);
72	}, $class;
73	}
74		247
75	=item $prev->transfer($next)	248	$class->SUPER::new (\&_new_coro, @_)
76
77	Save the state of the current subroutine in $prev and switch to the
78	coroutine saved in $next.
79
80	=cut
81
82	# I call the _transfer function from a perl function
83	# because that way perl saves all important things on
84	# the stack.
85	sub transfer {
86	_transfer($_[0], $_[1]);
87	}	249	}
88		250
89	=item $error, $error_msg, $error_coro	251	=item $process->ready
90		252
91	This coroutine will be called on fatal errors. C<$error_msg> and	253	Put the given process into the ready queue.
92	C<$error_coro> return the error message and the error-causing coroutine
93	(NOT an object) respectively. This API might change.
94		254
95	=cut	255	=cut
96		256
97	$error_msg =	257	=item $process->cancel (arg...)
98	$error_coro = undef;
99		258
100	$error = _newprocess {	259	Terminates the given process and makes it return the given arguments as
101	print STDERR "FATAL: $error_msg\nprogram aborted\n";	260	status (default: the empty list).
102	exit 50;	261
103	};	262	=cut
		263
		264	sub cancel {
		265	my $self = shift;
		266	$self->{status} = [@_];
		267	push @destroy, $self;
		268	$manager->ready;
		269	&schedule if $current == $self;
		270	}
		271
		272	=item $process->join
		273
		274	Wait until the coroutine terminates and return any values given to the
		275	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		276	from multiple processes.
		277
		278	=cut
		279
		280	sub join {
		281	my $self = shift;
		282	unless ($self->{status}) {
		283	push @{$self->{join}}, $current;
		284	&schedule;
		285	}
		286	wantarray ? @{$self->{status}} : $self->{status}[0];
		287	}
		288
		289	=item $oldprio = $process->prio ($newprio)
		290
		291	Sets (or gets, if the argument is missing) the priority of the
		292	process. Higher priority processes get run before lower priority
		293	processes. Priorities are small signed integers (currently -4 .. +3),
		294	that you can refer to using PRIO_xxx constants (use the import tag :prio
		295	to get then):
		296
		297	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		298	3 > 1 > 0 > -1 > -3 > -4
		299
		300	# set priority to HIGH
		301	current->prio(PRIO_HIGH);
		302
		303	The idle coroutine ($Coro::idle) always has a lower priority than any
		304	existing coroutine.
		305
		306	Changing the priority of the current process will take effect immediately,
		307	but changing the priority of processes in the ready queue (but not
		308	running) will only take effect after the next schedule (of that
		309	process). This is a bug that will be fixed in some future version.
		310
		311	=item $newprio = $process->nice ($change)
		312
		313	Similar to C<prio>, but subtract the given value from the priority (i.e.
		314	higher values mean lower priority, just as in unix).
		315
		316	=item $olddesc = $process->desc ($newdesc)
		317
		318	Sets (or gets in case the argument is missing) the description for this
		319	process. This is just a free-form string you can associate with a process.
		320
		321	=cut
		322
		323	sub desc {
		324	my $old = $_[0]{desc};
		325	$_[0]{desc} = $_[1] if @_ > 1;
		326	$old;
		327	}
		328
		329	=back
		330
		331	=cut
104		332
105	1;	333	1;
106		334
107	=back	335	=head1 BUGS/LIMITATIONS
108		336
109	=head1 BUGS	337	- you must make very sure that no coro is still active on global
		338	destruction. very bad things might happen otherwise (usually segfaults).
110		339
111	This module has not yet been extensively tested.	340	- this module is not thread-safe. You should only ever use this module
		341	from the same thread (this requirement might be losened in the future
		342	to allow per-thread schedulers, but Coro::State does not yet allow
		343	this).
112		344
113	=head1 SEE ALSO	345	=head1 SEE ALSO
114		346
115	L<Coro::Process>, L<Coro::Signal>.	347	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		348
		349	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		350
		351	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		352
		353	Embedding: L<Coro:MakeMaker>
116		354
117	=head1 AUTHOR	355	=head1 AUTHOR
118		356
119	Marc Lehmann <pcg@goof.com>	357	Marc Lehmann <schmorp@schmorp.de>
120	http://www.goof.com/pcg/marc/	358	http://home.schmorp.de/
121		359
122	=cut	360	=cut
123		361

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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 1.85 by root, Sat Nov 25 00:56:35 2006 UTC

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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 1.85 by root, Sat Nov 25 00:56:35 2006 UTC