[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 1.142 by root, Tue Oct 2 23:16:24 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 $VERSION = '3.8';
34	@EXPORT_OK = qw($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->{_on_destroy}) \|\| []};
		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	_pool_1 $cb;
		247	&$cb;
		248	_pool_2 $cb;
		249	&schedule;
		250	}
		251	};
		252
		253	last if $@ eq "\3terminate\2\n";
		254	warn $@ if $@;
		255	}
		256	}
		257
		258	sub async_pool(&@) {
		259	# this is also inlined into the unlock_scheduler
		260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		261
		262	$coro->{_invoke} = [@_];
		263	$coro->ready;
		264
		265	$coro
121	}	266	}
122		267
123	=item schedule	268	=item schedule
124		269
125	Calls the scheduler. Please note that the current process will not be put	270	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	271	into the ready queue, so calling this function usually means you will
127	never be called again.	272	never be called again unless something else (e.g. an event handler) calls
		273	ready.
128		274
129	=cut	275	The canonical way to wait on external events is this:
130		276
131	my $prev;	277	{
		278	# remember current coroutine
		279	my $current = $Coro::current;
132		280
133	sub schedule {	281	# register a hypothetical event handler
134	# should be done using priorities :(	282	on_event_invoke sub {
135	($prev, $current) = ($current, shift @ready \|\| $idle);	283	# wake up sleeping coroutine
136	Coro::State::transfer($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;	284	$current->ready;
148	&schedule;	285	undef $current;
149	}	286	};
150		287
		288	# call schedule until event occurred.
		289	# in case we are woken up for other reasons
		290	# (current still defined), loop.
		291	Coro::schedule while $current;
		292	}
		293
		294	=item cede
		295
		296	"Cede" to other coroutines. This function puts the current coroutine into the
		297	ready queue and calls C<schedule>, which has the effect of giving up the
		298	current "timeslice" to other coroutines of the same or higher priority.
		299
		300	Returns true if at least one coroutine switch has happened.
		301
		302	=item Coro::cede_notself
		303
		304	Works like cede, but is not exported by default and will cede to any
		305	coroutine, regardless of priority, once.
		306
		307	Returns true if at least one coroutine switch has happened.
		308
151	=item terminate	309	=item terminate [arg...]
152		310
153	Terminates the current process.	311	Terminates the current coroutine with the given status values (see L<cancel>).
		312
		313	=item killall
		314
		315	Kills/terminates/cancels all coroutines except the currently running
		316	one. This is useful after a fork, either in the child or the parent, as
		317	usually only one of them should inherit the running coroutines.
154		318
155	=cut	319	=cut
156		320
157	sub terminate {	321	sub terminate {
158	&schedule;	322	$current->cancel (@_);
		323	}
		324
		325	sub killall {
		326	for (Coro::State::list) {
		327	$_->cancel
		328	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		329	}
159	}	330	}
160		331
161	=back	332	=back
162		333
163	# dynamic methods	334	# dynamic methods
164		335
165	=head2 PROCESS METHODS	336	=head2 COROUTINE METHODS
166		337
167	These are the methods you can call on process objects.	338	These are the methods you can call on coroutine objects.
168		339
169	=over 4	340	=over 4
170		341
171	=item new Coro \⊂	342	=item new Coro \&sub [, @args...]
172		343
173	Create a new process and return it. When the sub returns the process	344	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	345	automatically terminates as if C<terminate> with the returned values were
		346	called. To make the coroutine run you must first put it into the ready queue
175	the ready queue by calling the ready method.	347	by calling the ready method.
176		348
		349	See C<async> for additional discussion.
		350
177	=cut	351	=cut
		352
		353	sub _run_coro {
		354	terminate &{+shift};
		355	}
178		356
179	sub new {	357	sub new {
180	my $class = shift;	358	my $class = shift;
		359
		360	$class->SUPER::new (\&_run_coro, @_)
		361	}
		362
		363	=item $success = $coroutine->ready
		364
		365	Put the given coroutine into the ready queue (according to it's priority)
		366	and return true. If the coroutine is already in the ready queue, do nothing
		367	and return false.
		368
		369	=item $is_ready = $coroutine->is_ready
		370
		371	Return wether the coroutine is currently the ready queue or not,
		372
		373	=item $coroutine->cancel (arg...)
		374
		375	Terminates the given coroutine and makes it return the given arguments as
		376	status (default: the empty list). Never returns if the coroutine is the
		377	current coroutine.
		378
		379	=cut
		380
		381	sub cancel {
		382	my $self = shift;
		383	$self->{_status} = [@_];
		384
		385	if ($current == $self) {
		386	push @destroy, $self;
		387	$manager->ready;
		388	&schedule while 1;
		389	} else {
		390	$self->_cancel;
		391	}
		392	}
		393
		394	=item $coroutine->join
		395
		396	Wait until the coroutine terminates and return any values given to the
		397	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		398	from multiple coroutine.
		399
		400	=cut
		401
		402	sub join {
		403	my $self = shift;
		404
		405	unless ($self->{_status}) {
		406	my $current = $current;
		407
		408	push @{$self->{_on_destroy}}, sub {
		409	$current->ready;
		410	undef $current;
		411	};
		412
		413	&schedule while $current;
		414	}
		415
		416	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		417	}
		418
		419	=item $coroutine->on_destroy (\&cb)
		420
		421	Registers a callback that is called when this coroutine gets destroyed,
		422	but before it is joined. The callback gets passed the terminate arguments,
		423	if any.
		424
		425	=cut
		426
		427	sub on_destroy {
		428	my ($self, $cb) = @_;
		429
		430	push @{ $self->{_on_destroy} }, $cb;
		431	}
		432
		433	=item $oldprio = $coroutine->prio ($newprio)
		434
		435	Sets (or gets, if the argument is missing) the priority of the
		436	coroutine. Higher priority coroutines get run before lower priority
		437	coroutines. Priorities are small signed integers (currently -4 .. +3),
		438	that you can refer to using PRIO_xxx constants (use the import tag :prio
		439	to get then):
		440
		441	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		442	3 > 1 > 0 > -1 > -3 > -4
		443
		444	# set priority to HIGH
		445	current->prio(PRIO_HIGH);
		446
		447	The idle coroutine ($Coro::idle) always has a lower priority than any
		448	existing coroutine.
		449
		450	Changing the priority of the current coroutine will take effect immediately,
		451	but changing the priority of coroutines in the ready queue (but not
		452	running) will only take effect after the next schedule (of that
		453	coroutine). This is a bug that will be fixed in some future version.
		454
		455	=item $newprio = $coroutine->nice ($change)
		456
		457	Similar to C<prio>, but subtract the given value from the priority (i.e.
		458	higher values mean lower priority, just as in unix).
		459
		460	=item $olddesc = $coroutine->desc ($newdesc)
		461
		462	Sets (or gets in case the argument is missing) the description for this
		463	coroutine. This is just a free-form string you can associate with a coroutine.
		464
		465	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		466	can modify this member directly if you wish.
		467
		468	=cut
		469
		470	sub desc {
181	my $proc = $_[0];	471	my $old = $_[0]{desc};
182	bless {	472	$_[0]{desc} = $_[1] if @_ > 1;
183	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	473	$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	}	474	}
196		475
197	=back	476	=back
198		477
		478	=head2 GLOBAL FUNCTIONS
		479
		480	=over 4
		481
		482	=item Coro::nready
		483
		484	Returns the number of coroutines that are currently in the ready state,
		485	i.e. that can be switched to. The value C<0> means that the only runnable
		486	coroutine is the currently running one, so C<cede> would have no effect,
		487	and C<schedule> would cause a deadlock unless there is an idle handler
		488	that wakes up some coroutines.
		489
		490	=item my $guard = Coro::guard { ... }
		491
		492	This creates and returns a guard object. Nothing happens until the object
		493	gets destroyed, in which case the codeblock given as argument will be
		494	executed. This is useful to free locks or other resources in case of a
		495	runtime error or when the coroutine gets canceled, as in both cases the
		496	guard block will be executed. The guard object supports only one method,
		497	C<< ->cancel >>, which will keep the codeblock from being executed.
		498
		499	Example: set some flag and clear it again when the coroutine gets canceled
		500	or the function returns:
		501
		502	sub do_something {
		503	my $guard = Coro::guard { $busy = 0 };
		504	$busy = 1;
		505
		506	# do something that requires $busy to be true
		507	}
		508
		509	=cut
		510
		511	sub guard(&) {
		512	bless \(my $cb = $_[0]), "Coro::guard"
		513	}
		514
		515	sub Coro::guard::cancel {
		516	${$_[0]} = sub { };
		517	}
		518
		519	sub Coro::guard::DESTROY {
		520	${$_[0]}->();
		521	}
		522
		523
		524	=item unblock_sub { ... }
		525
		526	This utility function takes a BLOCK or code reference and "unblocks" it,
		527	returning the new coderef. This means that the new coderef will return
		528	immediately without blocking, returning nothing, while the original code
		529	ref will be called (with parameters) from within its own coroutine.
		530
		531	The reason this function exists is that many event libraries (such as the
		532	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		533	of thread-safety). This means you must not block within event callbacks,
		534	otherwise you might suffer from crashes or worse.
		535
		536	This function allows your callbacks to block by executing them in another
		537	coroutine where it is safe to block. One example where blocking is handy
		538	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		539	disk.
		540
		541	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		542	creating event callbacks that want to block.
		543
		544	=cut
		545
		546	our @unblock_queue;
		547
		548	# we create a special coro because we want to cede,
		549	# to reduce pressure on the coro pool (because most callbacks
		550	# return immediately and can be reused) and because we cannot cede
		551	# inside an event callback.
		552	our $unblock_scheduler = new Coro sub {
		553	while () {
		554	while (my $cb = pop @unblock_queue) {
		555	# this is an inlined copy of async_pool
		556	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		557
		558	$coro->{_invoke} = $cb;
		559	$coro->ready;
		560	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		561	}
		562	schedule; # sleep well
		563	}
		564	};
		565	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		566
		567	sub unblock_sub(&) {
		568	my $cb = shift;
		569
		570	sub {
		571	unshift @unblock_queue, [$cb, @_];
		572	$unblock_scheduler->ready;
		573	}
		574	}
		575
		576	=back
		577
199	=cut	578	=cut
200		579
201	1;	580	1;
202		581
		582	=head1 BUGS/LIMITATIONS
		583
		584	- you must make very sure that no coro is still active on global
		585	destruction. very bad things might happen otherwise (usually segfaults).
		586
		587	- this module is not thread-safe. You should only ever use this module
		588	from the same thread (this requirement might be loosened in the future
		589	to allow per-thread schedulers, but Coro::State does not yet allow
		590	this).
		591
203	=head1 SEE ALSO	592	=head1 SEE ALSO
204		593
205	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	594	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
206	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	595
		596	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		597
		598	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		599
		600	Embedding: L<Coro:MakeMaker>
207		601
208	=head1 AUTHOR	602	=head1 AUTHOR
209		603
210	Marc Lehmann <pcg@goof.com>	604	Marc Lehmann <schmorp@schmorp.de>
211	http://www.goof.com/pcg/marc/	605	http://home.schmorp.de/
212		606
213	=cut	607	=cut
214		608

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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 1.142 by root, Tue Oct 2 23:16:24 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 1.142 by root, Tue Oct 2 23:16:24 2007 UTC