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

Comparing Coro/Coro.pm (file contents):
Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs.
Revision 1.134 by root, Sat Sep 22 14:42:56 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 = 0.04;	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	}
		96
		97	=over 4
63		98
64	=item $main	99	=item $main
65		100
66	This coroutine represents the main program.	101	This coroutine represents the main program.
67		102
68	=cut	103	=cut
69		104
70	our $main = new Coro;	105	$main = new Coro;
71		106
72	=item $current	107	=item $current (or as function: current)
73		108
74	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
75		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
76	=cut	116	=cut
		117
		118	$main->{desc} = "[main::]";
77		119
78	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
79	if ($current) {
80	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
81	}	122	if $current;
82		123
83	our $current = $main;	124	_set_current $main;
		125
		126	sub current() { $current }
84		127
85	=item $idle	128	=item $idle
86		129
87	The coroutine to switch to when no other coroutine is running. The default	130	A callback that is called whenever the scheduler finds no ready coroutines
88	implementation prints "FATAL: deadlock detected" and exits.	131	to run. The default implementation prints "FATAL: deadlock detected" and
		132	exits, because the program has no other way to continue.
89		133
90	=cut	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.
91		137
92	# should be done using priorities :(	138	Please note that if your callback recursively invokes perl (e.g. for event
93	our $idle = new Coro sub {	139	handlers), then it must be prepared to be called recursively.
94	print STDERR "FATAL: deadlock detected\n";	140
95	exit(51);	141	=cut
		142
		143	$idle = sub {
		144	require Carp;
		145	Carp::croak ("FATAL: deadlock detected");
96	};	146	};
97		147
98	# we really need priorities...	148	sub _cancel {
99	my @ready = (); # the ready queue. hehe, rather broken ;)	149	my ($self) = @_;
		150
		151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
		154
		155	# call all destruction callbacks
		156	$_->(@{$self->{status}})
		157	for @{(delete $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	# this coroutine is necessary because a coroutine
		161	# cannot destroy itself.
		162	my @destroy;
		163	my $manager;
		164
		165	$manager = new Coro sub {
		166	while () {
		167	(shift @destroy)->_cancel
		168	while @destroy;
		169
		170	&schedule;
		171	}
		172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
100		175
101	# static methods. not really.	176	# static methods. not really.
102		177
		178	=back
		179
103	=head2 STATIC METHODS	180	=head2 STATIC METHODS
104		181
105	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.
106		183
107	=over 4	184	=over 4
108		185
109	=item async { ... };	186	=item async { ... } [@args...]
110		187
111	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
112	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
113	terminated.	190	terminated.
114		191
115	=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.
116		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
117	sub async(&) {	203	sub async(&@) {
118	my $pid = new Coro $_[0];	204	my $coro = new Coro @_;
119	$pid->ready;	205	$coro->ready;
120	$pid;	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::POOL_RSS) it will also exit.
		233
		234	=cut
		235
		236	our $POOL_SIZE = 8;
		237	our $POOL_RSS = 16 * 1024;
		238	our @async_pool;
		239
		240	sub pool_handler {
		241	my $cb;
		242
		243	while () {
		244	eval {
		245	while () {
		246	$cb = &_pool_1
		247	or return;
		248
		249	&$cb;
		250
		251	return if &_pool_2;
		252
		253	undef $cb;
		254	schedule;
		255	}
		256	};
		257
		258	warn $@ if $@;
		259	}
		260	}
		261
		262	sub async_pool(&@) {
		263	# this is also inlined into the unlock_scheduler
		264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;;
		265
		266	$coro->{_invoke} = [@_];
		267	$coro->ready;
		268
		269	$coro
121	}	270	}
122		271
123	=item schedule	272	=item schedule
124		273
125	Calls the scheduler. Please note that the current process will not be put	274	Calls the scheduler. Please note that the current coroutine will not be put
126	into the ready queue, so calling this function usually means you will	275	into the ready queue, so calling this function usually means you will
127	never be called again.	276	never be called again unless something else (e.g. an event handler) calls
		277	ready.
128		278
129	=cut	279	The canonical way to wait on external events is this:
130		280
131	my $prev;	281	{
		282	# remember current coroutine
		283	my $current = $Coro::current;
132		284
133	sub schedule {	285	# register a hypothetical event handler
134	# should be done using priorities :(	286	on_event_invoke sub {
135	($prev, $current) = ($current, shift @ready \|\| $idle);	287	# wake up sleeping coroutine
136	Coro::State::transfer($prev, $current);
137	}
138
139	=item yield
140
141	Yield to other processes. This function puts the current process into the
142	ready queue and calls C<schedule>.
143
144	=cut
145
146	sub yield {
147	$current->ready;	288	$current->ready;
148	&schedule;	289	undef $current;
149	}	290	};
150		291
		292	# call schedule until event occurred.
		293	# in case we are woken up for other reasons
		294	# (current still defined), loop.
		295	Coro::schedule while $current;
		296	}
		297
		298	=item cede
		299
		300	"Cede" to other coroutines. This function puts the current coroutine into the
		301	ready queue and calls C<schedule>, which has the effect of giving up the
		302	current "timeslice" to other coroutines of the same or higher priority.
		303
		304	Returns true if at least one coroutine switch has happened.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to any
		309	coroutine, regardless of priority, once.
		310
		311	Returns true if at least one coroutine switch has happened.
		312
151	=item terminate	313	=item terminate [arg...]
152		314
153	Terminates the current process.	315	Terminates the current coroutine with the given status values (see L<cancel>).
154		316
155	=cut	317	=cut
156		318
157	sub terminate {	319	sub terminate {
158	&schedule;	320	$current->cancel (@_);
159	}	321	}
160		322
161	=back	323	=back
162		324
163	# dynamic methods	325	# dynamic methods
164		326
165	=head2 PROCESS METHODS	327	=head2 COROUTINE METHODS
166		328
167	These are the methods you can call on process objects.	329	These are the methods you can call on coroutine objects.
168		330
169	=over 4	331	=over 4
170		332
171	=item new Coro \⊂	333	=item new Coro \&sub [, @args...]
172		334
173	Create a new process and return it. When the sub returns the process	335	Create a new coroutine and return it. When the sub returns the coroutine
174	automatically terminates. To start the process you must first put it into	336	automatically terminates as if C<terminate> with the returned values were
		337	called. To make the coroutine run you must first put it into the ready queue
175	the ready queue by calling the ready method.	338	by calling the ready method.
176		339
		340	See C<async> for additional discussion.
		341
177	=cut	342	=cut
		343
		344	sub _run_coro {
		345	terminate &{+shift};
		346	}
178		347
179	sub new {	348	sub new {
180	my $class = shift;	349	my $class = shift;
		350
		351	$class->SUPER::new (\&_run_coro, @_)
		352	}
		353
		354	=item $success = $coroutine->ready
		355
		356	Put the given coroutine into the ready queue (according to it's priority)
		357	and return true. If the coroutine is already in the ready queue, do nothing
		358	and return false.
		359
		360	=item $is_ready = $coroutine->is_ready
		361
		362	Return wether the coroutine is currently the ready queue or not,
		363
		364	=item $coroutine->cancel (arg...)
		365
		366	Terminates the given coroutine and makes it return the given arguments as
		367	status (default: the empty list). Never returns if the coroutine is the
		368	current coroutine.
		369
		370	=cut
		371
		372	sub cancel {
		373	my $self = shift;
		374	$self->{status} = [@_];
		375
		376	if ($current == $self) {
		377	push @destroy, $self;
		378	$manager->ready;
		379	&schedule while 1;
		380	} else {
		381	$self->_cancel;
		382	}
		383	}
		384
		385	=item $coroutine->join
		386
		387	Wait until the coroutine terminates and return any values given to the
		388	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		389	from multiple coroutine.
		390
		391	=cut
		392
		393	sub join {
		394	my $self = shift;
		395
		396	unless ($self->{status}) {
		397	my $current = $current;
		398
		399	push @{$self->{destroy_cb}}, sub {
		400	$current->ready;
		401	undef $current;
		402	};
		403
		404	&schedule while $current;
		405	}
		406
		407	wantarray ? @{$self->{status}} : $self->{status}[0];
		408	}
		409
		410	=item $coroutine->on_destroy (\&cb)
		411
		412	Registers a callback that is called when this coroutine gets destroyed,
		413	but before it is joined. The callback gets passed the terminate arguments,
		414	if any.
		415
		416	=cut
		417
		418	sub on_destroy {
		419	my ($self, $cb) = @_;
		420
		421	push @{ $self->{destroy_cb} }, $cb;
		422	}
		423
		424	=item $oldprio = $coroutine->prio ($newprio)
		425
		426	Sets (or gets, if the argument is missing) the priority of the
		427	coroutine. Higher priority coroutines get run before lower priority
		428	coroutines. Priorities are small signed integers (currently -4 .. +3),
		429	that you can refer to using PRIO_xxx constants (use the import tag :prio
		430	to get then):
		431
		432	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		433	3 > 1 > 0 > -1 > -3 > -4
		434
		435	# set priority to HIGH
		436	current->prio(PRIO_HIGH);
		437
		438	The idle coroutine ($Coro::idle) always has a lower priority than any
		439	existing coroutine.
		440
		441	Changing the priority of the current coroutine will take effect immediately,
		442	but changing the priority of coroutines in the ready queue (but not
		443	running) will only take effect after the next schedule (of that
		444	coroutine). This is a bug that will be fixed in some future version.
		445
		446	=item $newprio = $coroutine->nice ($change)
		447
		448	Similar to C<prio>, but subtract the given value from the priority (i.e.
		449	higher values mean lower priority, just as in unix).
		450
		451	=item $olddesc = $coroutine->desc ($newdesc)
		452
		453	Sets (or gets in case the argument is missing) the description for this
		454	coroutine. This is just a free-form string you can associate with a coroutine.
		455
		456	=cut
		457
		458	sub desc {
181	my $proc = $_[0];	459	my $old = $_[0]{desc};
182	bless {	460	$_[0]{desc} = $_[1] if @_ > 1;
183	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	461	$old;
184	}, $class;
185	}
186
187	=item $process->ready
188
189	Put the current process into the ready queue.
190
191	=cut
192
193	sub ready {
194	push @ready, $_[0];
195	}	462	}
196		463
197	=back	464	=back
198		465
		466	=head2 GLOBAL FUNCTIONS
		467
		468	=over 4
		469
		470	=item Coro::nready
		471
		472	Returns the number of coroutines that are currently in the ready state,
		473	i.e. that can be switched to. The value C<0> means that the only runnable
		474	coroutine is the currently running one, so C<cede> would have no effect,
		475	and C<schedule> would cause a deadlock unless there is an idle handler
		476	that wakes up some coroutines.
		477
		478	=item my $guard = Coro::guard { ... }
		479
		480	This creates and returns a guard object. Nothing happens until the object
		481	gets destroyed, in which case the codeblock given as argument will be
		482	executed. This is useful to free locks or other resources in case of a
		483	runtime error or when the coroutine gets canceled, as in both cases the
		484	guard block will be executed. The guard object supports only one method,
		485	C<< ->cancel >>, which will keep the codeblock from being executed.
		486
		487	Example: set some flag and clear it again when the coroutine gets canceled
		488	or the function returns:
		489
		490	sub do_something {
		491	my $guard = Coro::guard { $busy = 0 };
		492	$busy = 1;
		493
		494	# do something that requires $busy to be true
		495	}
		496
		497	=cut
		498
		499	sub guard(&) {
		500	bless \(my $cb = $_[0]), "Coro::guard"
		501	}
		502
		503	sub Coro::guard::cancel {
		504	${$_[0]} = sub { };
		505	}
		506
		507	sub Coro::guard::DESTROY {
		508	${$_[0]}->();
		509	}
		510
		511
		512	=item unblock_sub { ... }
		513
		514	This utility function takes a BLOCK or code reference and "unblocks" it,
		515	returning the new coderef. This means that the new coderef will return
		516	immediately without blocking, returning nothing, while the original code
		517	ref will be called (with parameters) from within its own coroutine.
		518
		519	The reason this function exists is that many event libraries (such as the
		520	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		521	of thread-safety). This means you must not block within event callbacks,
		522	otherwise you might suffer from crashes or worse.
		523
		524	This function allows your callbacks to block by executing them in another
		525	coroutine where it is safe to block. One example where blocking is handy
		526	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		527	disk.
		528
		529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		530	creating event callbacks that want to block.
		531
		532	=cut
		533
		534	our @unblock_queue;
		535
		536	# we create a special coro because we want to cede,
		537	# to reduce pressure on the coro pool (because most callbacks
		538	# return immediately and can be reused) and because we cannot cede
		539	# inside an event callback.
		540	our $unblock_scheduler = new Coro sub {
		541	while () {
		542	while (my $cb = pop @unblock_queue) {
		543	# this is an inlined copy of async_pool
		544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		545
		546	$coro->{_invoke} = $cb;
		547	$coro->ready;
		548	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		549	}
		550	schedule; # sleep well
		551	}
		552	};
		553	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		554
		555	sub unblock_sub(&) {
		556	my $cb = shift;
		557
		558	sub {
		559	unshift @unblock_queue, [$cb, @_];
		560	$unblock_scheduler->ready;
		561	}
		562	}
		563
		564	=back
		565
199	=cut	566	=cut
200		567
201	1;	568	1;
202		569
		570	=head1 BUGS/LIMITATIONS
		571
		572	- you must make very sure that no coro is still active on global
		573	destruction. very bad things might happen otherwise (usually segfaults).
		574
		575	- this module is not thread-safe. You should only ever use this module
		576	from the same thread (this requirement might be loosened in the future
		577	to allow per-thread schedulers, but Coro::State does not yet allow
		578	this).
		579
203	=head1 SEE ALSO	580	=head1 SEE ALSO
204		581
205	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	582	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
206	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	583
		584	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		585
		586	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		587
		588	Embedding: L<Coro:MakeMaker>
207		589
208	=head1 AUTHOR	590	=head1 AUTHOR
209		591
210	Marc Lehmann <pcg@goof.com>	592	Marc Lehmann <schmorp@schmorp.de>
211	http://www.goof.com/pcg/marc/	593	http://home.schmorp.de/
212		594
213	=cut	595	=cut
214		596

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Comparing Coro/Coro.pm (file contents): Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs. Revision 1.134 by root, Sat Sep 22 14:42:56 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs.
Revision 1.134 by root, Sat Sep 22 14:42:56 2007 UTC