[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 1.90 by root, Thu Nov 30 18:21:14 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 $VERSION = '3.0';
		47
		48	our @EXPORT = qw(async cede schedule terminate current);
		49	our %EXPORT_TAGS = (
		50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		51	);
		52	our @EXPORT_OK = @{$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; $manager = new Coro sub {
		139	while () {
		140	# by overwriting the state object with the manager we destroy it
		141	# while still being able to schedule this coroutine (in case it has
		142	# been readied multiple times. this is harmless since the manager
		143	# can be called as many times as neccessary and will always
		144	# remove itself from the runqueue
		145	while (@destroy) {
		146	my $coro = pop @destroy;
		147	$coro->{status} \|\|= [];
		148	$_->ready for @{delete $coro->{join} \|\| []};
		149
		150	# the next line destroys the coro state, but keeps the
		151	# process itself intact (we basically make it a zombie
		152	# process that always runs the manager thread, so it's possible
		153	# to transfer() to this process).
		154	$coro->_clone_state_from ($manager);
		155	}
		156	&schedule;
		157	}
		158	};
		159
		160	# static methods. not really.
		161
		162	=back
		163
		164	=head2 STATIC METHODS
		165
		166	Static methods are actually functions that operate on the current process only.
		167
		168	=over 4
		169
		170	=item async { ... } [@args...]
		171
		172	Create a new asynchronous process and return it's process object
		173	(usually unused). When the sub returns the new process is automatically
		174	terminated.
		175
		176	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		177
		178	When the coroutine dies, the program will exit, just as in the main
		179	program.
		180
		181	# create a new coroutine that just prints its arguments
		182	async {
		183	print "@_\n";
		184	} 1,2,3,4;
		185
		186	=cut
		187
		188	sub async(&@) {
		189	my $pid = new Coro @_;
		190	$pid->ready;
		191	$pid
		192	}
		193
		194	=item schedule
		195
		196	Calls the scheduler. Please note that the current process will not be put
		197	into the ready queue, so calling this function usually means you will
		198	never be called again.
		199
		200	=cut
		201
		202	=item cede
		203
		204	"Cede" to other processes. This function puts the current process into the
		205	ready queue and calls C<schedule>, which has the effect of giving up the
		206	current "timeslice" to other coroutines of the same or higher priority.
		207
		208	=cut
		209
		210	=item terminate [arg...]
		211
		212	Terminates the current process with the given status values (see L<cancel>).
		213
		214	=cut
		215
		216	sub terminate {
		217	$current->cancel (@_);
		218	}
		219
		220	=back
		221
		222	# dynamic methods
		223
		224	=head2 PROCESS METHODS
		225
		226	These are the methods you can call on process objects.
		227
		228	=over 4
		229
		230	=item new Coro \&sub [, @args...]
		231
		232	Create a new process and return it. When the sub returns the process
		233	automatically terminates as if C<terminate> with the returned values were
		234	called. To make the process run you must first put it into the ready queue
		235	by calling the ready method.
		236
		237	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		238
		239	=cut
		240
		241	sub _new_coro {
		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	$class->SUPER::new (\&_new_coro, @_)
		249	}
76		250
77	Save the state of the current subroutine in C<$prev> and switch to the	251	=item $success = $process->ready
78	coroutine saved in C<$next>.
79		252
80	The "state" of a subroutine only ever includes scope, i.e. lexical	253	Put the given process into the ready queue (according to it's priority)
81	variables and the current execution state. It does not save/restore any	254	and return true. If the process is already in the ready queue, do nothing
82	global variables such as C<$_> or C<$@> or any other special or non	255	and return false.
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		256
88	The easiest way to do this is to create your own scheduling primitive like this:	257	=item $is_ready = $process->is_ready
89		258
90	sub schedule {	259	Return wether the process is currently the ready queue or not,
91	local ($_, $@, ...);	260
92	$old->transfer($new);	261	=item $process->cancel (arg...)
		262
		263	Terminates the given process and makes it return the given arguments as
		264	status (default: the empty list).
		265
		266	=cut
		267
		268	sub cancel {
		269	my $self = shift;
		270	$self->{status} = [@_];
		271	push @destroy, $self;
		272	$manager->ready;
		273	&schedule if $current == $self;
		274	}
		275
		276	=item $process->join
		277
		278	Wait until the coroutine terminates and return any values given to the
		279	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		280	from multiple processes.
		281
		282	=cut
		283
		284	sub join {
		285	my $self = shift;
		286	unless ($self->{status}) {
		287	push @{$self->{join}}, $current;
		288	&schedule;
93	}	289	}
94		290	wantarray ? @{$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	}	291	}
104		292
105	=item $error, $error_msg, $error_coro	293	=item $oldprio = $process->prio ($newprio)
106		294
107	This coroutine will be called on fatal errors. C<$error_msg> and	295	Sets (or gets, if the argument is missing) the priority of the
108	C<$error_coro> return the error message and the error-causing coroutine	296	process. Higher priority processes get run before lower priority
109	(NOT an object) respectively. This API might change.	297	processes. Priorities are small signed integers (currently -4 .. +3),
		298	that you can refer to using PRIO_xxx constants (use the import tag :prio
		299	to get then):
110		300
111	=cut	301	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		302	3 > 1 > 0 > -1 > -3 > -4
112		303
113	$error_msg =	304	# set priority to HIGH
114	$error_coro = undef;	305	current->prio(PRIO_HIGH);
115		306
116	$error = _newprocess {	307	The idle coroutine ($Coro::idle) always has a lower priority than any
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	308	existing coroutine.
118	exit 50;	309
119	};	310	Changing the priority of the current process will take effect immediately,
		311	but changing the priority of processes in the ready queue (but not
		312	running) will only take effect after the next schedule (of that
		313	process). This is a bug that will be fixed in some future version.
		314
		315	=item $newprio = $process->nice ($change)
		316
		317	Similar to C<prio>, but subtract the given value from the priority (i.e.
		318	higher values mean lower priority, just as in unix).
		319
		320	=item $olddesc = $process->desc ($newdesc)
		321
		322	Sets (or gets in case the argument is missing) the description for this
		323	process. This is just a free-form string you can associate with a process.
		324
		325	=cut
		326
		327	sub desc {
		328	my $old = $_[0]{desc};
		329	$_[0]{desc} = $_[1] if @_ > 1;
		330	$old;
		331	}
		332
		333	=back
		334
		335	=cut
120		336
121	1;	337	1;
122		338
123	=back	339	=head1 BUGS/LIMITATIONS
124		340
125	=head1 BUGS	341	- you must make very sure that no coro is still active on global
		342	destruction. very bad things might happen otherwise (usually segfaults).
126		343
127	This module has not yet been extensively tested.	344	- this module is not thread-safe. You should only ever use this module
		345	from the same thread (this requirement might be losened in the future
		346	to allow per-thread schedulers, but Coro::State does not yet allow
		347	this).
128		348
129	=head1 SEE ALSO	349	=head1 SEE ALSO
130		350
131	L<Coro::Process>, L<Coro::Signal>.	351	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		352
		353	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		354
		355	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		356
		357	Embedding: L<Coro:MakeMaker>
132		358
133	=head1 AUTHOR	359	=head1 AUTHOR
134		360
135	Marc Lehmann <pcg@goof.com>	361	Marc Lehmann <schmorp@schmorp.de>
136	http://www.goof.com/pcg/marc/	362	http://home.schmorp.de/
137		363
138	=cut	364	=cut
139		365

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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 1.90 by root, Thu Nov 30 18:21:14 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 1.90 by root, Thu Nov 30 18:21:14 2006 UTC