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

Comparing Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.112 by root, Sat Jan 20 19:52:15 2007 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
18		18
19	yield;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		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
23	=cut	40	=cut
24		41
25	package Coro;	42	package Coro;
26		43
		44	use strict;
		45	no warnings "uninitialized";
		46
27	use Coro::State;	47	use Coro::State;
28		48
29	use base Exporter;	49	use base qw(Coro::State Exporter);
30		50
31	$VERSION = 0.03;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
32		54
33	@EXPORT = qw(async yield schedule);	55	our $VERSION = '3.41';
34	@EXPORT_OK = qw($current);	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));
35		62
36	{	63	{
37	use subs 'async';
38
39	my @async;	64	my @async;
		65	my $init;
40		66
41	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
42	sub import {	68	sub import {
		69	no strict 'refs';
		70
43	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
44	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
45	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
46	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
47	my @attrs;	76	my @attrs;
48	for (@_) {	77	for (@_) {
49	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
50	push @async, $ref;	79	push @async, $ref;
		80	unless ($init++) {
		81	eval q{
		82	sub INIT {
		83	&async(pop @async) while @async;
		84	}
		85	};
		86	}
51	} else {	87	} else {
52	push @attrs, @_;	88	push @attrs, $_;
53	}	89	}
54	}	90	}
55	return $old ? $old->($package, $name, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
56	};	92	};
57	}	93	}
58		94
59	sub INIT {
60	async pop @async while @async;
61	}
62	}	95	}
63		96
64	my $idle = new Coro sub {	97	=over 4
65	&yield while 1;	98
		99	=item $main
		100
		101	This coroutine represents the main program.
		102
		103	=cut
		104
		105	$main = new Coro;
		106
		107	=item $current (or as function: current)
		108
		109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		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.
		115
		116	=cut
		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");
66	};	144	};
67		145
68	=item $main	146	sub _cancel {
		147	my ($self) = @_;
69		148
70	This coroutine represents the main program.	149	# free coroutine data and mark as destructed
		150	$self->_destroy
		151	or return;
71		152
72	=cut	153	# call all destruction callbacks
73		154	$_->(@{$self->{status}})
74	$main = new Coro;	155	for @{(delete $self->{destroy_cb}) \|\| []};
75
76	=item $current
77
78	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
79
80	=cut
81
82	# maybe some other module used Coro::Specific before...
83	if ($current) {
84	$main->{specific} = $current->{specific};
85	}	156	}
86		157
87	$current = $main;	158	# this coroutine is necessary because a coroutine
		159	# cannot destroy itself.
		160	my @destroy;
		161	my $manager;
88		162
89	# we really need priorities...	163	$manager = new Coro sub {
90	my @ready = (); # the ready queue. hehe, rather broken ;)	164	while () {
		165	(shift @destroy)->_cancel
		166	while @destroy;
		167
		168	&schedule;
		169	}
		170	};
		171
		172	$manager->prio (PRIO_MAX);
91		173
92	# static methods. not really.	174	# static methods. not really.
93		175
		176	=back
		177
94	=head2 STATIC METHODS	178	=head2 STATIC METHODS
95		179
96	Static methods are actually functions that operate on the current process only.	180	Static methods are actually functions that operate on the current coroutine only.
97		181
98	=over 4	182	=over 4
99		183
100	=item async { ... };	184	=item async { ... } [@args...]
101		185
102	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	188	terminated.
105		189
106	=cut	190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
107		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
		200	=cut
		201
108	sub async(&) {	202	sub async(&@) {
109	(new Coro $_[0])->ready;	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
		216	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		217	will not work in the expected way, unless you call terminate or cancel,
		218	which somehow defeats the purpose of pooling.
		219
		220	The priority will be reset to C<0> after each job, otherwise the coroutine
		221	will be re-used "as-is".
		222
		223	The pool size is limited to 8 idle coroutines (this can be adjusted by
		224	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		225	required.
		226
		227	If you are concerned about pooled coroutines growing a lot because a
		228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		229	terminate }> once per second or so to slowly replenish the pool.
		230
		231	=cut
		232
		233	our $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	eval {
		239	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		240	$cb->(@arg);
		241	};
		242	warn $@ if $@;
		243
		244	last if @pool >= $POOL_SIZE;
		245	push @pool, $current;
		246
		247	$current->prio (0);
		248	schedule;
		249	}
		250	}
		251
		252	sub async_pool(&@) {
		253	# this is also inlined into the unlock_scheduler
		254	my $coro = (pop @pool or new Coro \&pool_handler);
		255
		256	$coro->{_invoke} = [@_];
		257	$coro->ready;
		258
		259	$coro
110	}	260	}
111		261
112	=item schedule	262	=item schedule
113		263
114	Calls the scheduler. Please note that the current process will not be put	264	Calls the scheduler. Please note that the current coroutine will not be put
115	into the ready queue, so calling this function usually means you will	265	into the ready queue, so calling this function usually means you will
116	never be called again.	266	never be called again unless something else (e.g. an event handler) calls
		267	ready.
117		268
118	=cut	269	The canonical way to wait on external events is this:
119		270
120	my $prev;	271	{
		272	# remember current coroutine
		273	my $current = $Coro::current;
121		274
122	sub schedule {	275	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	276	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	277	# wake up sleeping coroutine
125	}
126
127	=item yield
128
129	Yield to other processes. This function puts the current process into the
130	ready queue and calls C<schedule>.
131
132	=cut
133
134	sub yield {
135	$current->ready;	278	$current->ready;
136	&schedule;	279	undef $current;
137	}	280	};
138		281
		282	# call schedule until event occured.
		283	# in case we are woken up for other reasons
		284	# (current still defined), loop.
		285	Coro::schedule while $current;
		286	}
		287
		288	=item cede
		289
		290	"Cede" to other coroutines. This function puts the current coroutine into the
		291	ready queue and calls C<schedule>, which has the effect of giving up the
		292	current "timeslice" to other coroutines of the same or higher priority.
		293
		294	Returns true if at least one coroutine switch has happened.
		295
		296	=item Coro::cede_notself
		297
		298	Works like cede, but is not exported by default and will cede to any
		299	coroutine, regardless of priority, once.
		300
		301	Returns true if at least one coroutine switch has happened.
		302
139	=item terminate	303	=item terminate [arg...]
140		304
141	Terminates the current process.	305	Terminates the current coroutine with the given status values (see L<cancel>).
142		306
143	=cut	307	=cut
144		308
145	sub terminate {	309	sub terminate {
146	&schedule;	310	$current->cancel (@_);
147	}	311	}
148		312
149	=back	313	=back
150		314
151	# dynamic methods	315	# dynamic methods
152		316
153	=head2 PROCESS METHODS	317	=head2 COROUTINE METHODS
154		318
155	These are the methods you can call on process objects.	319	These are the methods you can call on coroutine objects.
156		320
157	=over 4	321	=over 4
158		322
159	=item new Coro \⊂	323	=item new Coro \&sub [, @args...]
160		324
161	Create a new process and return it. When the sub returns the process	325	Create a new coroutine and return it. When the sub returns the coroutine
162	automatically terminates. To start the process you must first put it into	326	automatically terminates as if C<terminate> with the returned values were
		327	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	328	by calling the ready method.
164		329
		330	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		331
165	=cut	332	=cut
		333
		334	sub _run_coro {
		335	terminate &{+shift};
		336	}
166		337
167	sub new {	338	sub new {
168	my $class = shift;	339	my $class = shift;
		340
		341	$class->SUPER::new (\&_run_coro, @_)
		342	}
		343
		344	=item $success = $coroutine->ready
		345
		346	Put the given coroutine into the ready queue (according to it's priority)
		347	and return true. If the coroutine is already in the ready queue, do nothing
		348	and return false.
		349
		350	=item $is_ready = $coroutine->is_ready
		351
		352	Return wether the coroutine is currently the ready queue or not,
		353
		354	=item $coroutine->cancel (arg...)
		355
		356	Terminates the given coroutine and makes it return the given arguments as
		357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
		359
		360	=cut
		361
		362	sub cancel {
		363	my $self = shift;
		364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
		367	push @destroy, $self;
		368	$manager->ready;
		369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
		373	}
		374
		375	=item $coroutine->join
		376
		377	Wait until the coroutine terminates and return any values given to the
		378	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		379	from multiple coroutine.
		380
		381	=cut
		382
		383	sub join {
		384	my $self = shift;
		385
		386	unless ($self->{status}) {
		387	my $current = $current;
		388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
		395	}
		396
		397	wantarray ? @{$self->{status}} : $self->{status}[0];
		398	}
		399
		400	=item $coroutine->on_destroy (\&cb)
		401
		402	Registers a callback that is called when this coroutine gets destroyed,
		403	but before it is joined. The callback gets passed the terminate arguments,
		404	if any.
		405
		406	=cut
		407
		408	sub on_destroy {
		409	my ($self, $cb) = @_;
		410
		411	push @{ $self->{destroy_cb} }, $cb;
		412	}
		413
		414	=item $oldprio = $coroutine->prio ($newprio)
		415
		416	Sets (or gets, if the argument is missing) the priority of the
		417	coroutine. Higher priority coroutines get run before lower priority
		418	coroutines. Priorities are small signed integers (currently -4 .. +3),
		419	that you can refer to using PRIO_xxx constants (use the import tag :prio
		420	to get then):
		421
		422	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		423	3 > 1 > 0 > -1 > -3 > -4
		424
		425	# set priority to HIGH
		426	current->prio(PRIO_HIGH);
		427
		428	The idle coroutine ($Coro::idle) always has a lower priority than any
		429	existing coroutine.
		430
		431	Changing the priority of the current coroutine will take effect immediately,
		432	but changing the priority of coroutines in the ready queue (but not
		433	running) will only take effect after the next schedule (of that
		434	coroutine). This is a bug that will be fixed in some future version.
		435
		436	=item $newprio = $coroutine->nice ($change)
		437
		438	Similar to C<prio>, but subtract the given value from the priority (i.e.
		439	higher values mean lower priority, just as in unix).
		440
		441	=item $olddesc = $coroutine->desc ($newdesc)
		442
		443	Sets (or gets in case the argument is missing) the description for this
		444	coroutine. This is just a free-form string you can associate with a coroutine.
		445
		446	=cut
		447
		448	sub desc {
169	my $proc = $_[0];	449	my $old = $_[0]{desc};
170	bless {	450	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	451	$old;
172	}, $class;
173	}
174
175	=item $process->ready
176
177	Put the current process into the ready queue.
178
179	=cut
180
181	sub ready {
182	push @ready, $_[0];
183	}	452	}
184		453
185	=back	454	=back
186		455
		456	=head2 GLOBAL FUNCTIONS
		457
		458	=over 4
		459
		460	=item Coro::nready
		461
		462	Returns the number of coroutines that are currently in the ready state,
		463	i.e. that can be swicthed to. The value C<0> means that the only runnable
		464	coroutine is the currently running one, so C<cede> would have no effect,
		465	and C<schedule> would cause a deadlock unless there is an idle handler
		466	that wakes up some coroutines.
		467
		468	=item my $guard = Coro::guard { ... }
		469
		470	This creates and returns a guard object. Nothing happens until the objetc
		471	gets destroyed, in which case the codeblock given as argument will be
		472	executed. This is useful to free locks or other resources in case of a
		473	runtime error or when the coroutine gets canceled, as in both cases the
		474	guard block will be executed. The guard object supports only one method,
		475	C<< ->cancel >>, which will keep the codeblock from being executed.
		476
		477	Example: set some flag and clear it again when the coroutine gets canceled
		478	or the function returns:
		479
		480	sub do_something {
		481	my $guard = Coro::guard { $busy = 0 };
		482	$busy = 1;
		483
		484	# do something that requires $busy to be true
		485	}
		486
		487	=cut
		488
		489	sub guard(&) {
		490	bless \(my $cb = $_[0]), "Coro::guard"
		491	}
		492
		493	sub Coro::guard::cancel {
		494	${$_[0]} = sub { };
		495	}
		496
		497	sub Coro::guard::DESTROY {
		498	${$_[0]}->();
		499	}
		500
		501
		502	=item unblock_sub { ... }
		503
		504	This utility function takes a BLOCK or code reference and "unblocks" it,
		505	returning the new coderef. This means that the new coderef will return
		506	immediately without blocking, returning nothing, while the original code
		507	ref will be called (with parameters) from within its own coroutine.
		508
		509	The reason this fucntion exists is that many event libraries (such as the
		510	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		511	of thread-safety). This means you must not block within event callbacks,
		512	otherwise you might suffer from crashes or worse.
		513
		514	This function allows your callbacks to block by executing them in another
		515	coroutine where it is safe to block. One example where blocking is handy
		516	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		517	disk.
		518
		519	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		520	creating event callbacks that want to block.
		521
		522	=cut
		523
		524	our @unblock_queue;
		525
		526	# we create a special coro because we want to cede,
		527	# to reduce pressure on the coro pool (because most callbacks
		528	# return immediately and can be reused) and because we cannot cede
		529	# inside an event callback.
		530	our $unblock_scheduler = async {
		531	while () {
		532	while (my $cb = pop @unblock_queue) {
		533	# this is an inlined copy of async_pool
		534	my $coro = (pop @pool or new Coro \&pool_handler);
		535
		536	$coro->{_invoke} = $cb;
		537	$coro->ready;
		538	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		539	}
		540	schedule; # sleep well
		541	}
		542	};
		543
		544	sub unblock_sub(&) {
		545	my $cb = shift;
		546
		547	sub {
		548	unshift @unblock_queue, [$cb, @_];
		549	$unblock_scheduler->ready;
		550	}
		551	}
		552
		553	=back
		554
187	=cut	555	=cut
188		556
189	1;	557	1;
190		558
		559	=head1 BUGS/LIMITATIONS
		560
		561	- you must make very sure that no coro is still active on global
		562	destruction. very bad things might happen otherwise (usually segfaults).
		563
		564	- this module is not thread-safe. You should only ever use this module
		565	from the same thread (this requirement might be losened in the future
		566	to allow per-thread schedulers, but Coro::State does not yet allow
		567	this).
		568
		569	=head1 SEE ALSO
		570
		571	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		572
		573	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		574
		575	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		576
		577	Embedding: L<Coro:MakeMaker>
		578
191	=head1 AUTHOR	579	=head1 AUTHOR
192		580
193	Marc Lehmann <pcg@goof.com>	581	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	582	http://home.schmorp.de/
195		583
196	=cut	584	=cut
197		585

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Comparing Coro/Coro.pm (file contents): Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs. Revision 1.112 by root, Sat Jan 20 19:52:15 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.112 by root, Sat Jan 20 19:52:15 2007 UTC