[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 1.82 by root, Fri Nov 24 13:40:36 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 Exporter::;
		41
		42	our $idle; # idle coroutine
		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 $current (or as function: current)
		99
		100	The current coroutine (the last coroutine switched to). The initial value is C<$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	$coro->{_coro_state}->_clone_state_from ($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	When the coroutine dies, the program will exit, just as in the main
		169	program.
		170
		171	# create a new coroutine that just prints its arguments
		172	async {
		173	print "@_\n";
		174	} 1,2,3,4;
		175
		176	=cut
		177
		178	sub async(&@) {
		179	my $pid = new Coro @_;
		180	$manager->ready; # this ensures that the stack is cloned from the manager
		181	$pid->ready;
		182	$pid;
		183	}
		184
		185	=item schedule
		186
		187	Calls the scheduler. Please note that the current process will not be put
		188	into the ready queue, so calling this function usually means you will
		189	never be called again.
		190
		191	=cut
		192
		193	=item cede
		194
		195	"Cede" to other processes. This function puts the current process into the
		196	ready queue and calls C<schedule>, which has the effect of giving up the
		197	current "timeslice" to other coroutines of the same or higher priority.
		198
		199	=cut
		200
		201	=item terminate [arg...]
		202
		203	Terminates the current process with the given status values (see L<cancel>).
		204
		205	=cut
		206
		207	sub terminate {
		208	$current->cancel (@_);
		209	}
		210
		211	=back
		212
		213	# dynamic methods
		214
		215	=head2 PROCESS METHODS
		216
		217	These are the methods you can call on process objects.
		218
		219	=over 4
		220
		221	=item new Coro \&sub [, @args...]
		222
		223	Create a new process and return it. When the sub returns the process
		224	automatically terminates as if C<terminate> with the returned values were
		225	called. To make the process run you must first put it into the ready queue
		226	by calling the ready method.
		227
		228	=cut
		229
		230	sub _newcoro {
		231	terminate &{+shift};
		232	}
59		233
60	sub new {	234	sub new {
61	my $class = $_[0];	235	my $class = shift;
62	my $proc = $_[1] \|\| sub { die "tried to transfer to an empty coroutine" };	236	bless {
63	bless _newprocess {	237	_coro_state => (new Coro::State \&_newcoro, @_),
64	do {
65	eval { &$proc };
66	if ($@) {
67	$error_msg = $@;
68	$error_coro = _newprocess { };
69	&transfer($error_coro, $error);
70	}
71	} while (1);
72	}, $class;	238	}, $class;
73	}	239	}
74		240
75	=item $prev->transfer($next)	241	=item $process->ready
76		242
77	Save the state of the current subroutine in C<$prev> and switch to the	243	Put the given process into the ready queue.
78	coroutine saved in C<$next>.
79		244
80	The "state" of a subroutine only ever includes scope, i.e. lexical	245	=cut
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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		246
88	The easiest way to do this is to create your own scheduling primitive like this:	247	=item $process->cancel (arg...)
89		248
90	sub schedule {	249	Terminates the given process and makes it return the given arguments as
91	local ($_, $@, ...);	250	status (default: the empty list).
92	$old->transfer($new);	251
		252	=cut
		253
		254	sub cancel {
		255	my $self = shift;
		256	$self->{status} = [@_];
		257	push @destroy, $self;
		258	$manager->ready;
		259	&schedule if $current == $self;
		260	}
		261
		262	=item $process->join
		263
		264	Wait until the coroutine terminates and return any values given to the
		265	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		266	from multiple processes.
		267
		268	=cut
		269
		270	sub join {
		271	my $self = shift;
		272	unless ($self->{status}) {
		273	push @{$self->{join}}, $current;
		274	&schedule;
93	}	275	}
94		276	wantarray ? @{$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	}	277	}
104		278
105	=item $error, $error_msg, $error_coro	279	=item $oldprio = $process->prio ($newprio)
106		280
107	This coroutine will be called on fatal errors. C<$error_msg> and	281	Sets (or gets, if the argument is missing) the priority of the
108	C<$error_coro> return the error message and the error-causing coroutine	282	process. Higher priority processes get run before lower priority
109	(NOT an object) respectively. This API might change.	283	processes. Priorities are small signed integers (currently -4 .. +3),
		284	that you can refer to using PRIO_xxx constants (use the import tag :prio
		285	to get then):
110		286
111	=cut	287	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		288	3 > 1 > 0 > -1 > -3 > -4
112		289
113	$error_msg =	290	# set priority to HIGH
114	$error_coro = undef;	291	current->prio(PRIO_HIGH);
115		292
116	$error = _newprocess {	293	The idle coroutine ($Coro::idle) always has a lower priority than any
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	294	existing coroutine.
118	exit 50;	295
119	};	296	Changing the priority of the current process will take effect immediately,
		297	but changing the priority of processes in the ready queue (but not
		298	running) will only take effect after the next schedule (of that
		299	process). This is a bug that will be fixed in some future version.
		300
		301	=cut
		302
		303	sub prio {
		304	shift->{_coro_state}->prio (@_)
		305	}
		306
		307	=item $newprio = $process->nice ($change)
		308
		309	Similar to C<prio>, but subtract the given value from the priority (i.e.
		310	higher values mean lower priority, just as in unix).
		311
		312	=cut
		313
		314	sub nice {
		315	shift->{_coro_state}->nice (@_)
		316	}
		317
		318	=item $olddesc = $process->desc ($newdesc)
		319
		320	Sets (or gets in case the argument is missing) the description for this
		321	process. This is just a free-form string you can associate with a process.
		322
		323	=cut
		324
		325	sub desc {
		326	my $old = $_[0]{desc};
		327	$_[0]{desc} = $_[1] if @_ > 1;
		328	$old;
		329	}
		330
		331	=back
		332
		333	=cut
120		334
121	1;	335	1;
122		336
123	=back	337	=head1 BUGS/LIMITATIONS
124		338
125	=head1 BUGS	339	- you must make very sure that no coro is still active on global
		340	destruction. very bad things might happen otherwise (usually segfaults).
126		341
127	This module has not yet been extensively tested.	342	- this module is not thread-safe. You should only ever use this module
		343	from the same thread (this requirement might be losened in the future
		344	to allow per-thread schedulers, but Coro::State does not yet allow
		345	this).
128		346
129	=head1 SEE ALSO	347	=head1 SEE ALSO
130		348
131	L<Coro::Process>, L<Coro::Signal>.	349	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		350
		351	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		352
		353	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		354
		355	Embedding: L<Coro:MakeMaker>
132		356
133	=head1 AUTHOR	357	=head1 AUTHOR
134		358
135	Marc Lehmann <pcg@goof.com>	359	Marc Lehmann <schmorp@schmorp.de>
136	http://www.goof.com/pcg/marc/	360	http://home.schmorp.de/
137		361
138	=cut	362	=cut
139		363

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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 1.82 by root, Fri Nov 24 13:40:36 2006 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 1.82 by root, Fri Nov 24 13:40:36 2006 UTC