[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 1.61 by pcg, Fri May 14 13:25:08 2004 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	$VERSION = 0.97;
		44
		45	@EXPORT = qw(async cede schedule terminate current);
		46	%EXPORT_TAGS = (
		47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		48	);
		49	@EXPORT_OK = @{$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
		136	# the next line destroys the _coro_state, but keeps the
		137	# process itself intact (we basically make it a zombie
		138	# process that always runs the manager thread, so it's possible
		139	# to transfer() to this process).
		140	$coro->{_coro_state} = $manager->{_coro_state};
		141	}
		142	&schedule;
		143	}
		144	};
		145
		146	# static methods. not really.
		147
		148	=back
		149
		150	=head2 STATIC METHODS
		151
		152	Static methods are actually functions that operate on the current process only.
		153
		154	=over 4
		155
		156	=item async { ... } [@args...]
		157
		158	Create a new asynchronous process and return it's process object
		159	(usually unused). When the sub returns the new process is automatically
		160	terminated.
		161
		162	# create a new coroutine that just prints its arguments
		163	async {
		164	print "@_\n";
		165	} 1,2,3,4;
		166
		167	=cut
		168
		169	sub async(&@) {
		170	my $pid = new Coro @_;
		171	$manager->ready; # this ensures that the stack is cloned from the manager
		172	$pid->ready;
		173	$pid;
		174	}
		175
		176	=item schedule
		177
		178	Calls the scheduler. Please note that the current process will not be put
		179	into the ready queue, so calling this function usually means you will
		180	never be called again.
		181
		182	=cut
		183
		184	=item cede
		185
		186	"Cede" to other processes. This function puts the current process into the
		187	ready queue and calls C<schedule>, which has the effect of giving up the
		188	current "timeslice" to other coroutines of the same or higher priority.
		189
		190	=cut
		191
		192	=item terminate [arg...]
		193
		194	Terminates the current process with the given status values (see L<cancel>).
		195
		196	=cut
		197
		198	sub terminate {
		199	$current->cancel (@_);
		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 $process->ready
76		233
77	Save the state of the current subroutine in C<$prev> and switch to the	234	Put the given process into the ready queue.
78	coroutine saved in C<$next>.
79		235
80	The "state" of a subroutine only ever includes scope, i.e. lexical	236	=cut
81	variables and the current execution state. It does not save/restore any
82	global variables such as C<$_> 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		237
88	The easiest way to do this is to create your own scheduling primitive like this:	238	=item $process->cancel (arg...)
89		239
90	sub schedule {	240	Temrinates the given process and makes it return the given arguments as
91	local ($_, $@, ...);	241	status (default: the empty list).
92	$old->transfer($new);	242
		243	=cut
		244
		245	sub cancel {
		246	my $self = shift;
		247	$self->{status} = [@_];
		248	push @destroy, $self;
		249	$manager->ready;
		250	&schedule if $current == $self;
		251	}
		252
		253	=item $process->join
		254
		255	Wait until the coroutine terminates and return any values given to the
		256	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		257	from multiple processes.
		258
		259	=cut
		260
		261	sub join {
		262	my $self = shift;
		263	unless ($self->{status}) {
		264	push @{$self->{join}}, $current;
		265	&schedule;
93	}	266	}
94		267	wantarray ? @{$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	}	268	}
104		269
105	=item $error, $error_msg, $error_coro	270	=item $oldprio = $process->prio($newprio)
106		271
107	This coroutine will be called on fatal errors. C<$error_msg> and	272	Sets (or gets, if the argument is missing) the priority of the
108	C<$error_coro> return the error message and the error-causing coroutine	273	process. Higher priority processes get run before lower priority
109	(NOT an object) respectively. This API might change.	274	processes. Priorities are small signed integers (currently -4 .. +3),
		275	that you can refer to using PRIO_xxx constants (use the import tag :prio
		276	to get then):
110		277
111	=cut	278	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		279	3 > 1 > 0 > -1 > -3 > -4
112		280
113	$error_msg =	281	# set priority to HIGH
114	$error_coro = undef;	282	current->prio(PRIO_HIGH);
115		283
116	$error = _newprocess {	284	The idle coroutine ($Coro::idle) always has a lower priority than any
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	285	existing coroutine.
118	exit 50;	286
119	};	287	Changing the priority of the current process will take effect immediately,
		288	but changing the priority of processes in the ready queue (but not
		289	running) will only take effect after the next schedule (of that
		290	process). This is a bug that will be fixed in some future version.
		291
		292	=cut
		293
		294	sub prio {
		295	my $old = $_[0]{prio};
		296	$_[0]{prio} = $_[1] if @_ > 1;
		297	$old;
		298	}
		299
		300	=item $newprio = $process->nice($change)
		301
		302	Similar to C<prio>, but subtract the given value from the priority (i.e.
		303	higher values mean lower priority, just as in unix).
		304
		305	=cut
		306
		307	sub nice {
		308	$_[0]{prio} -= $_[1];
		309	}
		310
		311	=item $olddesc = $process->desc($newdesc)
		312
		313	Sets (or gets in case the argument is missing) the description for this
		314	process. This is just a free-form string you can associate with a process.
		315
		316	=cut
		317
		318	sub desc {
		319	my $old = $_[0]{desc};
		320	$_[0]{desc} = $_[1] if @_ > 1;
		321	$old;
		322	}
		323
		324	=back
		325
		326	=cut
120		327
121	1;	328	1;
122		329
123	=back	330	=head1 BUGS/LIMITATIONS
124		331
125	=head1 BUGS	332	- you must make very sure that no coro is still active on global
		333	destruction. very bad things might happen otherwise (usually segfaults).
126		334
127	This module has not yet been extensively tested.	335	- this module is not thread-safe. You should only ever use this module
		336	from the same thread (this requirement might be losened in the future
		337	to allow per-thread schedulers, but Coro::State does not yet allow
		338	this).
128		339
129	=head1 SEE ALSO	340	=head1 SEE ALSO
130		341
131	L<Coro::Process>, L<Coro::Signal>.	342	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
		343	L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>,
		344	L<Coro::L<Coro::RWLock>, Handle>, L<Coro::Socket>.
132		345
133	=head1 AUTHOR	346	=head1 AUTHOR
134		347
135	Marc Lehmann <pcg@goof.com>	348	Marc Lehmann <pcg@goof.com>
136	http://www.goof.com/pcg/marc/	349	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 1.61 by pcg, Fri May 14 13:25:08 2004 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs.
Revision 1.61 by pcg, Fri May 14 13:25:08 2004 UTC