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

Comparing Coro/Coro.pm (file contents):
Revision 1.1 by root, Tue Jul 3 02:53:34 2001 UTC vs.
Revision 1.107 by root, Fri Jan 5 18:25:51 2007 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - create an 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	async {
		10	# some asynchronous thread of execution
		11	};
		12
		13	# alternatively create an async coroutine like this:
		14
		15	sub some_func : Coro {
		16	# some more async code
		17	}
		18
		19	cede;
		20
9	=head1 DESCRIPTION	21	=head1 DESCRIPTION
10		22
		23	This module collection manages coroutines. Coroutines are similar
		24	to threads but don't run in parallel at the same time even on SMP
		25	machines. The specific flavor of coroutine use din this module also
		26	guarentees you that it will not switch between coroutines unless
		27	necessary, at easily-identified points in your program, so locking and
		28	parallel access are rarely an issue, making coroutine programming much
		29	safer than threads programming.
		30
		31	(Perl, however, does not natively support real threads but instead does a
		32	very slow and memory-intensive emulation of processes using threads. This
		33	is a performance win on Windows machines, and a loss everywhere else).
		34
		35	In this module, coroutines are defined as "callchain + lexical variables +
		36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
		37	its own set of lexicals and its own set of perls most important global
		38	variables.
		39
		40	=cut
		41
		42	package Coro;
		43
		44	use strict;
		45	no warnings "uninitialized";
		46
		47	use Coro::State;
		48
		49	use base qw(Coro::State Exporter);
		50
		51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
		54
		55	our $VERSION = '3.3';
		56
		57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
		58	our %EXPORT_TAGS = (
		59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		60	);
		61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
		62
		63	{
		64	my @async;
		65	my $init;
		66
		67	# this way of handling attributes simply is NOT scalable ;()
		68	sub import {
		69	no strict 'refs';
		70
		71	Coro->export_to_level (1, @_);
		72
		73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
		74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
		75	my ($package, $ref) = (shift, shift);
		76	my @attrs;
		77	for (@_) {
		78	if ($_ eq "Coro") {
		79	push @async, $ref;
		80	unless ($init++) {
		81	eval q{
		82	sub INIT {
		83	&async(pop @async) while @async;
		84	}
		85	};
		86	}
		87	} else {
		88	push @attrs, $_;
		89	}
		90	}
		91	return $old ? $old->($package, $ref, @attrs) : @attrs;
		92	};
		93	}
		94
		95	}
		96
11	=over 4	97	=over 4
12		98
13	=cut
14
15	package Coro;
16
17	BEGIN {
18	$VERSION = 0.01;
19
20	require XSLoader;
21	XSLoader::load Coro, $VERSION;
22	}
23
24	=item $main	99	=item $main
25		100
26	This coroutine represents the main program.	101	This coroutine represents the main program.
27		102
28	=item $current	103	=cut
29		104
		105	$main = new Coro;
		106
		107	=item $current (or as function: current)
		108
30	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
31		111
32	=cut	112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
33		115
34	$main = $current = _newprocess {	116	=cut
35	# never being called	117
		118	# maybe some other module used Coro::Specific before...
		119	$main->{specific} = $current->{specific}
		120	if $current;
		121
		122	_set_current $main;
		123
		124	sub current() { $current }
		125
		126	=item $idle
		127
		128	A callback that is called whenever the scheduler finds no ready coroutines
		129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
		131
		132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
		135
		136	Please note that if your callback recursively invokes perl (e.g. for event
		137	handlers), then it must be prepared to be called recursively.
		138
		139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
36	};	144	};
37		145
38	=item $error, $error_msg, $error_coro	146	sub _cancel {
		147	my ($self) = @_;
39		148
40	This coroutine will be called on fatal errors. C<$error_msg> and	149	# free coroutine data and mark as destructed
41	C<$error_coro> return the error message and the error-causing coroutine,	150	$self->_destroy
42	respectively.	151	or return;
43		152
44	=cut	153	# call all destruction callbacks
		154	$_->(@{$self->{status}})
		155	for @{(delete $self->{destroy_cb}) \|\| []};
		156	}
45		157
46	$error_msg =	158	# this coroutine is necessary because a coroutine
47	$error_coro = undef;	159	# cannot destroy itself.
		160	my @destroy;
		161	my $manager;
48		162
49	$error = _newprocess {	163	$manager = new Coro sub {
50	print STDERR "FATAL: $error_msg, program aborted\n";	164	while () {
51	exit 250;	165	(shift @destroy)->_cancel
		166	while @destroy;
		167
		168	&schedule;
		169	}
52	};	170	};
53		171
54	=item $coro = new $coderef [, @args]	172	$manager->prio (PRIO_MAX);
55		173
56	Create a new coroutine and return it. The first C<resume> call to this	174	# static methods. not really.
57	coroutine will start execution at the given coderef. If it returns it
58	should return a coroutine to switch to. If, after returning, the coroutine
59	is C<resume>d again it starts execution again at the givne coderef.
60		175
		176	=back
		177
		178	=head2 STATIC METHODS
		179
		180	Static methods are actually functions that operate on the current coroutine only.
		181
		182	=over 4
		183
		184	=item async { ... } [@args...]
		185
		186	Create a new asynchronous coroutine and return it's coroutine object
		187	(usually unused). When the sub returns the new coroutine is automatically
		188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
		194
		195	# create a new coroutine that just prints its arguments
		196	async {
		197	print "@_\n";
		198	} 1,2,3,4;
		199
61	=cut	200	=cut
		201
		202	sub async(&@) {
		203	my $coro = new Coro @_;
		204	$coro->ready;
		205	$coro
		206	}
		207
		208	=item async_pool { ... } [@args...]
		209
		210	Similar to C<async>, but uses a coroutine pool, so you should not call
		211	terminate or join (although you are allowed to), and you get a coroutine
		212	that might have executed other code already (which can be good or bad :).
		213
		214	Also, the block is executed in an C<eval> context and a warning will be
		215	issued in case of an exception instead of terminating the program, as C<async> does.
		216
		217	The priority will be reset to C<0> after each job, otherwise the coroutine
		218	will be re-used "as-is".
		219
		220	The pool size is limited to 8 idle coroutines (this can be adjusted by
		221	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		222	required.
		223
		224	If you are concerned about pooled coroutines growing a lot because a
		225	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		226	terminate }> once per second or so to slowly replenish the pool.
		227
		228	=cut
		229
		230	our $POOL_SIZE = 8;
		231	our @pool;
		232
		233	sub pool_handler {
		234	while () {
		235	my ($cb, @arg) = @{ delete $current->{_invoke} };
		236
		237	eval {
		238	$cb->(@arg);
		239	};
		240	warn $@ if $@;
		241
		242	last if @pool >= $POOL_SIZE;
		243	push @pool, $current;
		244
		245	$current->prio (0);
		246	schedule;
		247	}
		248	}
		249
		250	sub async_pool(&@) {
		251	# this is also inlined into the unlock_scheduler
		252	my $coro = (pop @pool or new Coro \&pool_handler);
		253
		254	$coro->{_invoke} = [@_];
		255	$coro->ready;
		256
		257	$coro
		258	}
		259
		260	=item schedule
		261
		262	Calls the scheduler. Please note that the current coroutine will not be put
		263	into the ready queue, so calling this function usually means you will
		264	never be called again unless something else (e.g. an event handler) calls
		265	ready.
		266
		267	The canonical way to wait on external events is this:
		268
		269	{
		270	# remember current coroutine
		271	my $current = $Coro::current;
		272
		273	# register a hypothetical event handler
		274	on_event_invoke sub {
		275	# wake up sleeping coroutine
		276	$current->ready;
		277	undef $current;
		278	};
		279
		280	# call schedule until event occured.
		281	# in case we are woken up for other reasons
		282	# (current still defined), loop.
		283	Coro::schedule while $current;
		284	}
		285
		286	=item cede
		287
		288	"Cede" to other coroutines. This function puts the current coroutine into the
		289	ready queue and calls C<schedule>, which has the effect of giving up the
		290	current "timeslice" to other coroutines of the same or higher priority.
		291
		292	Returns true if at least one coroutine switch has happened.
		293
		294	=item Coro::cede_notself
		295
		296	Works like cede, but is not exported by default and will cede to any
		297	coroutine, regardless of priority, once.
		298
		299	Returns true if at least one coroutine switch has happened.
		300
		301	=item terminate [arg...]
		302
		303	Terminates the current coroutine with the given status values (see L<cancel>).
		304
		305	=cut
		306
		307	sub terminate {
		308	$current->cancel (@_);
		309	}
		310
		311	=back
		312
		313	# dynamic methods
		314
		315	=head2 COROUTINE METHODS
		316
		317	These are the methods you can call on coroutine objects.
		318
		319	=over 4
		320
		321	=item new Coro \&sub [, @args...]
		322
		323	Create a new coroutine and return it. When the sub returns the coroutine
		324	automatically terminates as if C<terminate> with the returned values were
		325	called. To make the coroutine run you must first put it into the ready queue
		326	by calling the ready method.
		327
		328	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		329
		330	=cut
		331
		332	sub _run_coro {
		333	terminate &{+shift};
		334	}
62		335
63	sub new {	336	sub new {
64	my $class = $_[0];	337	my $class = shift;
65	my $proc = $_[1];	338
66	bless _newprocess {	339	$class->SUPER::new (\&_run_coro, @_)
67	do {	340	}
68	eval { &$proc->resume };	341
69	if ($@) {	342	=item $success = $coroutine->ready
70	($error_msg, $error_coro) = ($@, $current);	343
71	$error->resume;	344	Put the given coroutine into the ready queue (according to it's priority)
		345	and return true. If the coroutine is already in the ready queue, do nothing
		346	and return false.
		347
		348	=item $is_ready = $coroutine->is_ready
		349
		350	Return wether the coroutine is currently the ready queue or not,
		351
		352	=item $coroutine->cancel (arg...)
		353
		354	Terminates the given coroutine and makes it return the given arguments as
		355	status (default: the empty list). Never returns if the coroutine is the
		356	current coroutine.
		357
		358	=cut
		359
		360	sub cancel {
		361	my $self = shift;
		362	$self->{status} = [@_];
		363
		364	if ($current == $self) {
		365	push @destroy, $self;
		366	$manager->ready;
		367	&schedule while 1;
		368	} else {
		369	$self->_cancel;
		370	}
		371	}
		372
		373	=item $coroutine->join
		374
		375	Wait until the coroutine terminates and return any values given to the
		376	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		377	from multiple coroutine.
		378
		379	=cut
		380
		381	sub join {
		382	my $self = shift;
		383
		384	unless ($self->{status}) {
		385	my $current = $current;
		386
		387	push @{$self->{destroy_cb}}, sub {
		388	$current->ready;
		389	undef $current;
		390	};
		391
		392	&schedule while $current;
		393	}
		394
		395	wantarray ? @{$self->{status}} : $self->{status}[0];
		396	}
		397
		398	=item $coroutine->on_destroy (\&cb)
		399
		400	Registers a callback that is called when this coroutine gets destroyed,
		401	but before it is joined. The callback gets passed the terminate arguments,
		402	if any.
		403
		404	=cut
		405
		406	sub on_destroy {
		407	my ($self, $cb) = @_;
		408
		409	push @{ $self->{destroy_cb} }, $cb;
		410	}
		411
		412	=item $oldprio = $coroutine->prio ($newprio)
		413
		414	Sets (or gets, if the argument is missing) the priority of the
		415	coroutine. Higher priority coroutines get run before lower priority
		416	coroutines. Priorities are small signed integers (currently -4 .. +3),
		417	that you can refer to using PRIO_xxx constants (use the import tag :prio
		418	to get then):
		419
		420	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		421	3 > 1 > 0 > -1 > -3 > -4
		422
		423	# set priority to HIGH
		424	current->prio(PRIO_HIGH);
		425
		426	The idle coroutine ($Coro::idle) always has a lower priority than any
		427	existing coroutine.
		428
		429	Changing the priority of the current coroutine will take effect immediately,
		430	but changing the priority of coroutines in the ready queue (but not
		431	running) will only take effect after the next schedule (of that
		432	coroutine). This is a bug that will be fixed in some future version.
		433
		434	=item $newprio = $coroutine->nice ($change)
		435
		436	Similar to C<prio>, but subtract the given value from the priority (i.e.
		437	higher values mean lower priority, just as in unix).
		438
		439	=item $olddesc = $coroutine->desc ($newdesc)
		440
		441	Sets (or gets in case the argument is missing) the description for this
		442	coroutine. This is just a free-form string you can associate with a coroutine.
		443
		444	=cut
		445
		446	sub desc {
		447	my $old = $_[0]{desc};
		448	$_[0]{desc} = $_[1] if @_ > 1;
		449	$old;
		450	}
		451
		452	=back
		453
		454	=head2 GLOBAL FUNCTIONS
		455
		456	=over 4
		457
		458	=item Coro::nready
		459
		460	Returns the number of coroutines that are currently in the ready state,
		461	i.e. that can be swicthed to. The value C<0> means that the only runnable
		462	coroutine is the currently running one, so C<cede> would have no effect,
		463	and C<schedule> would cause a deadlock unless there is an idle handler
		464	that wakes up some coroutines.
		465
		466	=item my $guard = Coro::guard { ... }
		467
		468	This creates and returns a guard object. Nothing happens until the objetc
		469	gets destroyed, in which case the codeblock given as argument will be
		470	executed. This is useful to free locks or other resources in case of a
		471	runtime error or when the coroutine gets canceled, as in both cases the
		472	guard block will be executed. The guard object supports only one method,
		473	C<< ->cancel >>, which will keep the codeblock from being executed.
		474
		475	Example: set some flag and clear it again when the coroutine gets canceled
		476	or the function returns:
		477
		478	sub do_something {
		479	my $guard = Coro::guard { $busy = 0 };
		480	$busy = 1;
		481
		482	# do something that requires $busy to be true
		483	}
		484
		485	=cut
		486
		487	sub guard(&) {
		488	bless \(my $cb = $_[0]), "Coro::guard"
		489	}
		490
		491	sub Coro::guard::cancel {
		492	${$_[0]} = sub { };
		493	}
		494
		495	sub Coro::guard::DESTROY {
		496	${$_[0]}->();
		497	}
		498
		499
		500	=item unblock_sub { ... }
		501
		502	This utility function takes a BLOCK or code reference and "unblocks" it,
		503	returning the new coderef. This means that the new coderef will return
		504	immediately without blocking, returning nothing, while the original code
		505	ref will be called (with parameters) from within its own coroutine.
		506
		507	The reason this fucntion exists is that many event libraries (such as the
		508	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		509	of thread-safety). This means you must not block within event callbacks,
		510	otherwise you might suffer from crashes or worse.
		511
		512	This function allows your callbacks to block by executing them in another
		513	coroutine where it is safe to block. One example where blocking is handy
		514	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		515	disk.
		516
		517	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		518	creating event callbacks that want to block.
		519
		520	=cut
		521
		522	our @unblock_queue;
		523
		524	# we create a special coro because we want to cede,
		525	# to reduce pressure on the coro pool (because most callbacks
		526	# return immediately and can be reused) and because we cannot cede
		527	# inside an event callback.
		528	our $unblock_scheduler = async {
		529	while () {
		530	while (my $cb = pop @unblock_queue) {
		531	# this is an inlined copy of async_pool
		532	my $coro = (pop @pool or new Coro \&pool_handler);
		533
		534	$coro->{_invoke} = $cb;
		535	$coro->ready;
		536	cede; # for short-lived callbacks, this reduces pressure on the coro pool
72	}	537	}
73	} while ();	538	schedule; # sleep well
74	}, $class;	539	}
75	}	540	};
76		541
77	=item $coro->resume	542	sub unblock_sub(&) {
		543	my $cb = shift;
78		544
79	Resume execution at the given coroutine.	545	sub {
80		546	unshift @unblock_queue, [$cb, @_];
81	=cut	547	$unblock_scheduler->ready;
82		548	}
83	my $prev;
84
85	sub resume {
86	$prev = $current; $current = $_[0];
87	_transfer($prev, $current);
88	}	549	}
		550
		551	=back
		552
		553	=cut
89		554
90	1;	555	1;
91		556
92	=back	557	=head1 BUGS/LIMITATIONS
93		558
94	=head1 BUGS	559	- you must make very sure that no coro is still active on global
		560	destruction. very bad things might happen otherwise (usually segfaults).
95		561
96	This module has not yet been extensively tested.	562	- this module is not thread-safe. You should only ever use this module
		563	from the same thread (this requirement might be losened in the future
		564	to allow per-thread schedulers, but Coro::State does not yet allow
		565	this).
		566
		567	=head1 SEE ALSO
		568
		569	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		570
		571	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		572
		573	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		574
		575	Embedding: L<Coro:MakeMaker>
97		576
98	=head1 AUTHOR	577	=head1 AUTHOR
99		578
100	Marc Lehmann <pcg@goof.com>	579	Marc Lehmann <schmorp@schmorp.de>
101	http://www.goof.com/pcg/marc/	580	http://home.schmorp.de/
102		581
103	=cut	582	=cut
104		583

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Comparing Coro/Coro.pm (file contents): Revision 1.1 by root, Tue Jul 3 02:53:34 2001 UTC vs. Revision 1.107 by root, Fri Jan 5 18:25:51 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.1 by root, Tue Jul 3 02:53:34 2001 UTC vs.
Revision 1.107 by root, Fri Jan 5 18:25:51 2007 UTC