[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 1.86 by root, Sat Nov 25 01:14:11 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; $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	When the coroutine dies, the program will exit, just as in the main
		177	program.
		178
		179	# create a new coroutine that just prints its arguments
		180	async {
		181	print "@_\n";
		182	} 1,2,3,4;
		183
		184	=cut
		185
		186	sub async(&@) {
		187	my $pid = new Coro @_;
		188	$pid->ready;
		189	$pid
		190	}
		191
		192	=item schedule
		193
		194	Calls the scheduler. Please note that the current process will not be put
		195	into the ready queue, so calling this function usually means you will
		196	never be called again.
		197
		198	=cut
		199
		200	=item cede
		201
		202	"Cede" to other processes. This function puts the current process into the
		203	ready queue and calls C<schedule>, which has the effect of giving up the
		204	current "timeslice" to other coroutines of the same or higher priority.
		205
		206	=cut
		207
		208	=item terminate [arg...]
		209
		210	Terminates the current process with the given status values (see L<cancel>).
		211
		212	=cut
		213
		214	sub terminate {
		215	$current->cancel (@_);
		216	}
		217
		218	=back
		219
		220	# dynamic methods
		221
		222	=head2 PROCESS METHODS
		223
		224	These are the methods you can call on process objects.
		225
		226	=over 4
		227
		228	=item new Coro \&sub [, @args...]
		229
		230	Create a new process and return it. When the sub returns the process
		231	automatically terminates as if C<terminate> with the returned values were
		232	called. To make the process run you must first put it into the ready queue
		233	by calling the ready method.
		234
		235	=cut
		236
		237	sub _new_coro {
		238	$current->_clear_idle_sp; # (re-)set the idle sp on the following cede
		239	_set_cede_self; # ensures that cede cede's us first
		240	cede;
		241	terminate &{+shift};
		242	}
59		243
60	sub new {	244	sub new {
61	my $class = $_[0];	245	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		246
75	=item $prev->transfer($next)	247	$class->SUPER::new (\&_new_coro, @_)
		248	}
76		249
77	Save the state of the current subroutine in C<$prev> and switch to the	250	=item $process->ready
78	coroutine saved in C<$next>.
79		251
80	The "state" of a subroutine only ever includes scope, i.e. lexical	252	Put the given process into the ready queue.
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		253
88	The easiest way to do this is to create your own scheduling primitive like this:	254	=cut
89		255
90	sub schedule {	256	=item $process->cancel (arg...)
91	local ($_, $@, ...);	257
92	$old->transfer($new);	258	Terminates the given process and makes it return the given arguments as
		259	status (default: the empty list).
		260
		261	=cut
		262
		263	sub cancel {
		264	my $self = shift;
		265	$self->{status} = [@_];
		266	push @destroy, $self;
		267	$manager->ready;
		268	&schedule if $current == $self;
		269	}
		270
		271	=item $process->join
		272
		273	Wait until the coroutine terminates and return any values given to the
		274	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		275	from multiple processes.
		276
		277	=cut
		278
		279	sub join {
		280	my $self = shift;
		281	unless ($self->{status}) {
		282	push @{$self->{join}}, $current;
		283	&schedule;
93	}	284	}
94		285	wantarray ? @{$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	}	286	}
104		287
105	=item $error, $error_msg, $error_coro	288	=item $oldprio = $process->prio ($newprio)
106		289
107	This coroutine will be called on fatal errors. C<$error_msg> and	290	Sets (or gets, if the argument is missing) the priority of the
108	C<$error_coro> return the error message and the error-causing coroutine	291	process. Higher priority processes get run before lower priority
109	(NOT an object) respectively. This API might change.	292	processes. Priorities are small signed integers (currently -4 .. +3),
		293	that you can refer to using PRIO_xxx constants (use the import tag :prio
		294	to get then):
110		295
111	=cut	296	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		297	3 > 1 > 0 > -1 > -3 > -4
112		298
113	$error_msg =	299	# set priority to HIGH
114	$error_coro = undef;	300	current->prio(PRIO_HIGH);
115		301
116	$error = _newprocess {	302	The idle coroutine ($Coro::idle) always has a lower priority than any
117	print STDERR "FATAL: $error_msg\nprogram aborted\n";	303	existing coroutine.
118	exit 50;	304
119	};	305	Changing the priority of the current process will take effect immediately,
		306	but changing the priority of processes in the ready queue (but not
		307	running) will only take effect after the next schedule (of that
		308	process). This is a bug that will be fixed in some future version.
		309
		310	=item $newprio = $process->nice ($change)
		311
		312	Similar to C<prio>, but subtract the given value from the priority (i.e.
		313	higher values mean lower priority, just as in unix).
		314
		315	=item $olddesc = $process->desc ($newdesc)
		316
		317	Sets (or gets in case the argument is missing) the description for this
		318	process. This is just a free-form string you can associate with a process.
		319
		320	=cut
		321
		322	sub desc {
		323	my $old = $_[0]{desc};
		324	$_[0]{desc} = $_[1] if @_ > 1;
		325	$old;
		326	}
		327
		328	=back
		329
		330	=cut
120		331
121	1;	332	1;
122		333
123	=back	334	=head1 BUGS/LIMITATIONS
124		335
125	=head1 BUGS	336	- you must make very sure that no coro is still active on global
		337	destruction. very bad things might happen otherwise (usually segfaults).
126		338
127	This module has not yet been extensively tested.	339	- this module is not thread-safe. You should only ever use this module
		340	from the same thread (this requirement might be losened in the future
		341	to allow per-thread schedulers, but Coro::State does not yet allow
		342	this).
128		343
129	=head1 SEE ALSO	344	=head1 SEE ALSO
130		345
131	L<Coro::Process>, L<Coro::Signal>.	346	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		347
		348	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		349
		350	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		351
		352	Embedding: L<Coro:MakeMaker>
132		353
133	=head1 AUTHOR	354	=head1 AUTHOR
134		355
135	Marc Lehmann <pcg@goof.com>	356	Marc Lehmann <schmorp@schmorp.de>
136	http://www.goof.com/pcg/marc/	357	http://home.schmorp.de/
137		358
138	=cut	359	=cut
139		360

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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 1.86 by root, Sat Nov 25 01:14:11 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 1.86 by root, Sat Nov 25 01:14:11 2006 UTC