[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 1.133 by root, Fri Sep 21 01:23:58 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 used in this module also
		26	guarantees 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 $VERSION = '3.7';
34	@EXPORT_OK = qw($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 essential you are encouraged to use the
		114	C<Coro::current> function instead.
		115
		116	=cut
		117
		118	$main->{desc} = "[main::]";
		119
		120	# maybe some other module used Coro::Specific before...
		121	$main->{specific} = $current->{specific}
		122	if $current;
		123
		124	_set_current $main;
		125
		126	sub current() { $current }
		127
		128	=item $idle
		129
		130	A callback that is called whenever the scheduler finds no ready coroutines
		131	to run. The default implementation prints "FATAL: deadlock detected" and
		132	exits, because the program has no other way to continue.
		133
		134	This hook is overwritten by modules such as C<Coro::Timer> and
		135	C<Coro::Event> to wait on an external event that hopefully wake up a
		136	coroutine so the scheduler can run it.
		137
		138	Please note that if your callback recursively invokes perl (e.g. for event
		139	handlers), then it must be prepared to be called recursively.
		140
		141	=cut
		142
		143	$idle = sub {
		144	require Carp;
		145	Carp::croak ("FATAL: deadlock detected");
66	};	146	};
67		147
68	=item $main	148	sub _cancel {
		149	my ($self) = @_;
69		150
70	This coroutine represents the main program.	151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
71		154
72	=cut	155	# call all destruction callbacks
73		156	$_->(@{$self->{status}})
74	$main = new Coro;	157	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	}	158	}
86		159
87	$current = $main;	160	# this coroutine is necessary because a coroutine
		161	# cannot destroy itself.
		162	my @destroy;
		163	my $manager;
88		164
89	# we really need priorities...	165	$manager = new Coro sub {
90	my @ready = (); # the ready queue. hehe, rather broken ;)	166	while () {
		167	(shift @destroy)->_cancel
		168	while @destroy;
		169
		170	&schedule;
		171	}
		172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
91		175
92	# static methods. not really.	176	# static methods. not really.
93		177
		178	=back
		179
94	=head2 STATIC METHODS	180	=head2 STATIC METHODS
95		181
96	Static methods are actually functions that operate on the current process only.	182	Static methods are actually functions that operate on the current coroutine only.
97		183
98	=over 4	184	=over 4
99		185
100	=item async { ... };	186	=item async { ... } [@args...]
101		187
102	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	190	terminated.
105		191
106	=cut	192	Calling C<exit> in a coroutine will do the same as calling exit outside
		193	the coroutine. Likewise, when the coroutine dies, the program will exit,
		194	just as it would in the main program.
107		195
		196	# create a new coroutine that just prints its arguments
		197	async {
		198	print "@_\n";
		199	} 1,2,3,4;
		200
		201	=cut
		202
108	sub async(&) {	203	sub async(&@) {
109	(new Coro $_[0])->ready;	204	my $coro = new Coro @_;
		205	$coro->ready;
		206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		230	{ terminate }> once per second or so to slowly replenish the pool. In
		231	addition to that, when the stacks used by a handler grows larger than 16kb
		232	(adjustable with $Coro::MAX_POOL_RSS) it will also exit.
		233
		234	=cut
		235
		236	our $POOL_SIZE = 8;
		237	our $MAX_POOL_RSS = 16 * 1024;
		238	our @pool;
		239
		240	sub pool_handler {
		241	while () {
		242	$current->{desc} = "[async_pool]";
		243
		244	eval {
		245	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		246	$cb->(@arg);
		247	};
		248	warn $@ if $@;
		249
		250	last if @pool >= $POOL_SIZE \|\| $current->rss >= $MAX_POOL_RSS;
		251
		252	push @pool, $current;
		253	$current->{desc} = "[async_pool idle]";
		254	$current->save (Coro::State::SAVE_DEF);
		255	$current->prio (0);
		256	schedule;
		257	}
		258	}
		259
		260	sub async_pool(&@) {
		261	# this is also inlined into the unlock_scheduler
		262	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		263
		264	$coro->{_invoke} = [@_];
		265	$coro->ready;
		266
		267	$coro
110	}	268	}
111		269
112	=item schedule	270	=item schedule
113		271
114	Calls the scheduler. Please note that the current process will not be put	272	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	273	into the ready queue, so calling this function usually means you will
116	never be called again.	274	never be called again unless something else (e.g. an event handler) calls
		275	ready.
117		276
118	=cut	277	The canonical way to wait on external events is this:
119		278
120	my $prev;	279	{
		280	# remember current coroutine
		281	my $current = $Coro::current;
121		282
122	sub schedule {	283	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	284	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	285	# 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;	286	$current->ready;
136	&schedule;	287	undef $current;
137	}	288	};
138		289
		290	# call schedule until event occurred.
		291	# in case we are woken up for other reasons
		292	# (current still defined), loop.
		293	Coro::schedule while $current;
		294	}
		295
		296	=item cede
		297
		298	"Cede" to other coroutines. This function puts the current coroutine into the
		299	ready queue and calls C<schedule>, which has the effect of giving up the
		300	current "timeslice" to other coroutines of the same or higher priority.
		301
		302	Returns true if at least one coroutine switch has happened.
		303
		304	=item Coro::cede_notself
		305
		306	Works like cede, but is not exported by default and will cede to any
		307	coroutine, regardless of priority, once.
		308
		309	Returns true if at least one coroutine switch has happened.
		310
139	=item terminate	311	=item terminate [arg...]
140		312
141	Terminates the current process.	313	Terminates the current coroutine with the given status values (see L<cancel>).
142		314
143	=cut	315	=cut
144		316
145	sub terminate {	317	sub terminate {
146	&schedule;	318	$current->cancel (@_);
147	}	319	}
148		320
149	=back	321	=back
150		322
151	# dynamic methods	323	# dynamic methods
152		324
153	=head2 PROCESS METHODS	325	=head2 COROUTINE METHODS
154		326
155	These are the methods you can call on process objects.	327	These are the methods you can call on coroutine objects.
156		328
157	=over 4	329	=over 4
158		330
159	=item new Coro \⊂	331	=item new Coro \&sub [, @args...]
160		332
161	Create a new process and return it. When the sub returns the process	333	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	334	automatically terminates as if C<terminate> with the returned values were
		335	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	336	by calling the ready method.
164		337
		338	See C<async> for additional discussion.
		339
165	=cut	340	=cut
		341
		342	sub _run_coro {
		343	terminate &{+shift};
		344	}
166		345
167	sub new {	346	sub new {
168	my $class = shift;	347	my $class = shift;
		348
		349	$class->SUPER::new (\&_run_coro, @_)
		350	}
		351
		352	=item $success = $coroutine->ready
		353
		354	Put the given coroutine into the ready queue (according to it's priority)
		355	and return true. If the coroutine is already in the ready queue, do nothing
		356	and return false.
		357
		358	=item $is_ready = $coroutine->is_ready
		359
		360	Return wether the coroutine is currently the ready queue or not,
		361
		362	=item $coroutine->cancel (arg...)
		363
		364	Terminates the given coroutine and makes it return the given arguments as
		365	status (default: the empty list). Never returns if the coroutine is the
		366	current coroutine.
		367
		368	=cut
		369
		370	sub cancel {
		371	my $self = shift;
		372	$self->{status} = [@_];
		373
		374	if ($current == $self) {
		375	push @destroy, $self;
		376	$manager->ready;
		377	&schedule while 1;
		378	} else {
		379	$self->_cancel;
		380	}
		381	}
		382
		383	=item $coroutine->join
		384
		385	Wait until the coroutine terminates and return any values given to the
		386	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		387	from multiple coroutine.
		388
		389	=cut
		390
		391	sub join {
		392	my $self = shift;
		393
		394	unless ($self->{status}) {
		395	my $current = $current;
		396
		397	push @{$self->{destroy_cb}}, sub {
		398	$current->ready;
		399	undef $current;
		400	};
		401
		402	&schedule while $current;
		403	}
		404
		405	wantarray ? @{$self->{status}} : $self->{status}[0];
		406	}
		407
		408	=item $coroutine->on_destroy (\&cb)
		409
		410	Registers a callback that is called when this coroutine gets destroyed,
		411	but before it is joined. The callback gets passed the terminate arguments,
		412	if any.
		413
		414	=cut
		415
		416	sub on_destroy {
		417	my ($self, $cb) = @_;
		418
		419	push @{ $self->{destroy_cb} }, $cb;
		420	}
		421
		422	=item $oldprio = $coroutine->prio ($newprio)
		423
		424	Sets (or gets, if the argument is missing) the priority of the
		425	coroutine. Higher priority coroutines get run before lower priority
		426	coroutines. Priorities are small signed integers (currently -4 .. +3),
		427	that you can refer to using PRIO_xxx constants (use the import tag :prio
		428	to get then):
		429
		430	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		431	3 > 1 > 0 > -1 > -3 > -4
		432
		433	# set priority to HIGH
		434	current->prio(PRIO_HIGH);
		435
		436	The idle coroutine ($Coro::idle) always has a lower priority than any
		437	existing coroutine.
		438
		439	Changing the priority of the current coroutine will take effect immediately,
		440	but changing the priority of coroutines in the ready queue (but not
		441	running) will only take effect after the next schedule (of that
		442	coroutine). This is a bug that will be fixed in some future version.
		443
		444	=item $newprio = $coroutine->nice ($change)
		445
		446	Similar to C<prio>, but subtract the given value from the priority (i.e.
		447	higher values mean lower priority, just as in unix).
		448
		449	=item $olddesc = $coroutine->desc ($newdesc)
		450
		451	Sets (or gets in case the argument is missing) the description for this
		452	coroutine. This is just a free-form string you can associate with a coroutine.
		453
		454	=cut
		455
		456	sub desc {
169	my $proc = $_[0];	457	my $old = $_[0]{desc};
170	bless {	458	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	459	$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	}	460	}
184		461
185	=back	462	=back
186		463
		464	=head2 GLOBAL FUNCTIONS
		465
		466	=over 4
		467
		468	=item Coro::nready
		469
		470	Returns the number of coroutines that are currently in the ready state,
		471	i.e. that can be switched to. The value C<0> means that the only runnable
		472	coroutine is the currently running one, so C<cede> would have no effect,
		473	and C<schedule> would cause a deadlock unless there is an idle handler
		474	that wakes up some coroutines.
		475
		476	=item my $guard = Coro::guard { ... }
		477
		478	This creates and returns a guard object. Nothing happens until the object
		479	gets destroyed, in which case the codeblock given as argument will be
		480	executed. This is useful to free locks or other resources in case of a
		481	runtime error or when the coroutine gets canceled, as in both cases the
		482	guard block will be executed. The guard object supports only one method,
		483	C<< ->cancel >>, which will keep the codeblock from being executed.
		484
		485	Example: set some flag and clear it again when the coroutine gets canceled
		486	or the function returns:
		487
		488	sub do_something {
		489	my $guard = Coro::guard { $busy = 0 };
		490	$busy = 1;
		491
		492	# do something that requires $busy to be true
		493	}
		494
		495	=cut
		496
		497	sub guard(&) {
		498	bless \(my $cb = $_[0]), "Coro::guard"
		499	}
		500
		501	sub Coro::guard::cancel {
		502	${$_[0]} = sub { };
		503	}
		504
		505	sub Coro::guard::DESTROY {
		506	${$_[0]}->();
		507	}
		508
		509
		510	=item unblock_sub { ... }
		511
		512	This utility function takes a BLOCK or code reference and "unblocks" it,
		513	returning the new coderef. This means that the new coderef will return
		514	immediately without blocking, returning nothing, while the original code
		515	ref will be called (with parameters) from within its own coroutine.
		516
		517	The reason this function exists is that many event libraries (such as the
		518	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		519	of thread-safety). This means you must not block within event callbacks,
		520	otherwise you might suffer from crashes or worse.
		521
		522	This function allows your callbacks to block by executing them in another
		523	coroutine where it is safe to block. One example where blocking is handy
		524	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		525	disk.
		526
		527	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		528	creating event callbacks that want to block.
		529
		530	=cut
		531
		532	our @unblock_queue;
		533
		534	# we create a special coro because we want to cede,
		535	# to reduce pressure on the coro pool (because most callbacks
		536	# return immediately and can be reused) and because we cannot cede
		537	# inside an event callback.
		538	our $unblock_scheduler = new Coro sub {
		539	while () {
		540	while (my $cb = pop @unblock_queue) {
		541	# this is an inlined copy of async_pool
		542	my $coro = (pop @pool or new Coro \&pool_handler);
		543
		544	$coro->{_invoke} = $cb;
		545	$coro->ready;
		546	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		547	}
		548	schedule; # sleep well
		549	}
		550	};
		551	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		552
		553	sub unblock_sub(&) {
		554	my $cb = shift;
		555
		556	sub {
		557	unshift @unblock_queue, [$cb, @_];
		558	$unblock_scheduler->ready;
		559	}
		560	}
		561
		562	=back
		563
187	=cut	564	=cut
188		565
189	1;	566	1;
190		567
		568	=head1 BUGS/LIMITATIONS
		569
		570	- you must make very sure that no coro is still active on global
		571	destruction. very bad things might happen otherwise (usually segfaults).
		572
		573	- this module is not thread-safe. You should only ever use this module
		574	from the same thread (this requirement might be loosened in the future
		575	to allow per-thread schedulers, but Coro::State does not yet allow
		576	this).
		577
		578	=head1 SEE ALSO
		579
		580	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		581
		582	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		583
		584	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		585
		586	Embedding: L<Coro:MakeMaker>
		587
191	=head1 AUTHOR	588	=head1 AUTHOR
192		589
193	Marc Lehmann <pcg@goof.com>	590	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	591	http://home.schmorp.de/
195		592
196	=cut	593	=cut
197		594

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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 1.133 by root, Fri Sep 21 01:23:58 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 1.133 by root, Fri Sep 21 01:23:58 2007 UTC