[ViewVC] Diff of: cvs/Coro/Coro.pm

Comparing Coro/Coro.pm (file contents):
Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs.
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - create and manage 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	$Coro::main->resume;
12	print "in coroutine again, switching back\n";
13	$Coro::main->resume;
14	};	11	};
15		12
16	print "in main, switching to coroutine\n";	13	# alternatively create an async process like this:
17	$new->resume;	14
18	print "back in main, switch to coroutine again\n";	15	sub some_func : Coro {
19	$new->resume;	16	# some more async code
20	print "back in main\n";	17	}
		18
		19	cede;
21		20
22	=head1 DESCRIPTION	21	=head1 DESCRIPTION
23		22
24	This module implements coroutines. Coroutines, similar to continuations,	23	This module collection manages coroutines. Coroutines are similar to
25	allow you to run more than one "thread of execution" in parallel. Unlike	24	threads but don't run in parallel.
26	threads this, only voluntary switching is used so locking problems are
27	greatly reduced.
28		25
29	Although this is the "main" module of the Coro family it provides only	26	In this module, coroutines are defined as "callchain + lexical variables
30	low-level functionality. See L<Coro::Process> and related modules for a	27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
31	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	}
32		87
33	=over 4	88	=over 4
34		89
35	=cut
36
37	package Coro;
38
39	BEGIN {
40	$VERSION = 0.01;
41
42	require XSLoader;
43	XSLoader::load Coro, $VERSION;
44	}
45
46	=item $main	90	=item $main
47		91
48	This coroutine represents the main program.	92	This coroutine represents the main program.
49		93
50	=item $current	94	=cut
51		95
		96	$main = new Coro;
		97
		98	=item $current (or as function: current)
		99
52	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	100	The current coroutine (the last coroutine switched to). The initial value
		101	is C<$main> (of course).
53		102
54	=cut	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.
55		106
56	$main = $current = _newprocess {	107	=cut
57	# never being called	108
		109	# maybe some other module used Coro::Specific before...
		110	if ($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, because the program has no other way to continue.
		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 wake up a
		126	coroutine so the scheduler can run it.
		127
		128	Please note that if your callback recursively invokes perl (e.g. for event
		129	handlers), then it must be prepared to be called recursively.
		130
		131	=cut
		132
		133	$idle = sub {
		134	print STDERR "FATAL: deadlock detected\n";
		135	exit (51);
58	};	136	};
59		137
60	=item $error, $error_msg, $error_coro	138	# this coroutine is necessary because a coroutine
		139	# cannot destroy itself.
		140	my @destroy;
		141	my $manager; $manager = new Coro sub {
		142	while () {
		143	# by overwriting the state object with the manager we destroy it
		144	# while still being able to schedule this coroutine (in case it has
		145	# been readied multiple times. this is harmless since the manager
		146	# can be called as many times as neccessary and will always
		147	# remove itself from the runqueue
		148	while (@destroy) {
		149	my $coro = pop @destroy;
		150	$coro->{status} \|\|= [];
		151	$_->ready for @{delete $coro->{join} \|\| []};
61		152
62	This coroutine will be called on fatal errors. C<$error_msg> and	153	# the next line destroys the coro state, but keeps the
63	C<$error_coro> return the error message and the error-causing coroutine,	154	# process itself intact (we basically make it a zombie
64	respectively.	155	# process that always runs the manager thread, so it's possible
65		156	# to transfer() to this process).
66	=cut	157	$coro->_clone_state_from ($manager);
67		158	}
68	$error_msg =	159	&schedule;
69	$error_coro = undef;	160	}
70
71	$error = _newprocess {
72	print STDERR "FATAL: $error_msg\nprogram aborted\n";
73	exit 250;
74	};	161	};
75		162
76	=item $coro = new $coderef [, @args]	163	# static methods. not really.
77		164
78	Create a new coroutine and return it. The first C<resume> call to this	165	=back
79	coroutine will start execution at the given coderef. If it returns it
80	should return a coroutine to switch to. If, after returning, the coroutine
81	is C<resume>d again it starts execution again at the givne coderef.
82		166
		167	=head2 STATIC METHODS
		168
		169	Static methods are actually functions that operate on the current process only.
		170
		171	=over 4
		172
		173	=item async { ... } [@args...]
		174
		175	Create a new asynchronous process and return it's process object
		176	(usually unused). When the sub returns the new process is automatically
		177	terminated.
		178
		179	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		180
		181	When the coroutine dies, the program will exit, just as in the main
		182	program.
		183
		184	# create a new coroutine that just prints its arguments
		185	async {
		186	print "@_\n";
		187	} 1,2,3,4;
		188
83	=cut	189	=cut
		190
		191	sub async(&@) {
		192	my $pid = new Coro @_;
		193	$pid->ready;
		194	$pid
		195	}
		196
		197	=item schedule
		198
		199	Calls the scheduler. Please note that the current process will not be put
		200	into the ready queue, so calling this function usually means you will
		201	never be called again unless something else (e.g. an event handler) calls
		202	ready.
		203
		204	The canonical way to wait on external events is this:
		205
		206	{
		207	# remember current process
		208	my $current = $Coro::current;
		209
		210	# register a hypothetical event handler
		211	on_event_invoke sub {
		212	# wake up sleeping coroutine
		213	$current->ready;
		214	undef $current;
		215	};
		216
		217	# call schedule until event occured.
		218	# in case we are woken up for other reasons
		219	# (current still defined), loop.
		220	Coro::schedule while $current;
		221	}
		222
		223	=cut
		224
		225	=item cede
		226
		227	"Cede" to other processes. This function puts the current process into the
		228	ready queue and calls C<schedule>, which has the effect of giving up the
		229	current "timeslice" to other coroutines of the same or higher priority.
		230
		231	=cut
		232
		233	=item terminate [arg...]
		234
		235	Terminates the current process with the given status values (see L<cancel>).
		236
		237	=cut
		238
		239	sub terminate {
		240	$current->cancel (@_);
		241	}
		242
		243	=back
		244
		245	# dynamic methods
		246
		247	=head2 PROCESS METHODS
		248
		249	These are the methods you can call on process objects.
		250
		251	=over 4
		252
		253	=item new Coro \&sub [, @args...]
		254
		255	Create a new process and return it. When the sub returns the process
		256	automatically terminates as if C<terminate> with the returned values were
		257	called. To make the process run you must first put it into the ready queue
		258	by calling the ready method.
		259
		260	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		261
		262	=cut
		263
		264	sub _new_coro {
		265	terminate &{+shift};
		266	}
84		267
85	sub new {	268	sub new {
86	my $class = $_[0];	269	my $class = shift;
87	my $proc = $_[1];
88	bless _newprocess {
89	do {
90	eval { &$proc->resume };
91	if ($@) {
92	($error_msg, $error_coro) = ($@, $current);
93	$error->resume;
94	}
95	} while (1);
96	}, $class;
97	}
98		270
99	=item $coro->resume	271	$class->SUPER::new (\&_new_coro, @_)
100
101	Resume execution at the given coroutine.
102
103	=cut
104
105	my $prev;
106
107	sub resume {
108	$prev = $current; $current = $_[0];
109	_transfer($prev, $current);
110	}	272	}
		273
		274	=item $success = $process->ready
		275
		276	Put the given process into the ready queue (according to it's priority)
		277	and return true. If the process is already in the ready queue, do nothing
		278	and return false.
		279
		280	=item $is_ready = $process->is_ready
		281
		282	Return wether the process is currently the ready queue or not,
		283
		284	=item $process->cancel (arg...)
		285
		286	Terminates the given process and makes it return the given arguments as
		287	status (default: the empty list).
		288
		289	=cut
		290
		291	sub cancel {
		292	my $self = shift;
		293	$self->{status} = [@_];
		294	push @destroy, $self;
		295	$manager->ready;
		296	&schedule if $current == $self;
		297	}
		298
		299	=item $process->join
		300
		301	Wait until the coroutine terminates and return any values given to the
		302	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		303	from multiple processes.
		304
		305	=cut
		306
		307	sub join {
		308	my $self = shift;
		309	unless ($self->{status}) {
		310	push @{$self->{join}}, $current;
		311	&schedule;
		312	}
		313	wantarray ? @{$self->{status}} : $self->{status}[0];
		314	}
		315
		316	=item $oldprio = $process->prio ($newprio)
		317
		318	Sets (or gets, if the argument is missing) the priority of the
		319	process. Higher priority processes get run before lower priority
		320	processes. Priorities are small signed integers (currently -4 .. +3),
		321	that you can refer to using PRIO_xxx constants (use the import tag :prio
		322	to get then):
		323
		324	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		325	3 > 1 > 0 > -1 > -3 > -4
		326
		327	# set priority to HIGH
		328	current->prio(PRIO_HIGH);
		329
		330	The idle coroutine ($Coro::idle) always has a lower priority than any
		331	existing coroutine.
		332
		333	Changing the priority of the current process will take effect immediately,
		334	but changing the priority of processes in the ready queue (but not
		335	running) will only take effect after the next schedule (of that
		336	process). This is a bug that will be fixed in some future version.
		337
		338	=item $newprio = $process->nice ($change)
		339
		340	Similar to C<prio>, but subtract the given value from the priority (i.e.
		341	higher values mean lower priority, just as in unix).
		342
		343	=item $olddesc = $process->desc ($newdesc)
		344
		345	Sets (or gets in case the argument is missing) the description for this
		346	process. This is just a free-form string you can associate with a process.
		347
		348	=cut
		349
		350	sub desc {
		351	my $old = $_[0]{desc};
		352	$_[0]{desc} = $_[1] if @_ > 1;
		353	$old;
		354	}
		355
		356	=back
		357
		358	=cut
111		359
112	1;	360	1;
113		361
114	=back	362	=head1 BUGS/LIMITATIONS
115		363
116	=head1 BUGS	364	- you must make very sure that no coro is still active on global
		365	destruction. very bad things might happen otherwise (usually segfaults).
117		366
118	This module has not yet been extensively tested.	367	- this module is not thread-safe. You should only ever use this module
		368	from the same thread (this requirement might be losened in the future
		369	to allow per-thread schedulers, but Coro::State does not yet allow
		370	this).
119		371
120	=head1 SEE ALSO	372	=head1 SEE ALSO
121		373
122	L<Coro::Process>, L<Coro::Signal>.	374	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		375
		376	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		377
		378	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		379
		380	Embedding: L<Coro:MakeMaker>
123		381
124	=head1 AUTHOR	382	=head1 AUTHOR
125		383
126	Marc Lehmann <pcg@goof.com>	384	Marc Lehmann <schmorp@schmorp.de>
127	http://www.goof.com/pcg/marc/	385	http://home.schmorp.de/
128		386
129	=cut	387	=cut
130		388

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Comparing Coro/Coro.pm (file contents): Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs. Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.4 by root, Tue Jul 3 05:05:45 2001 UTC vs.
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC