[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 1.136 by root, Sat Sep 22 22:59:31 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	_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>).
154		312
155	=cut	313	=cut
156		314
157	sub terminate {	315	sub terminate {
158	&schedule;	316	$current->cancel (@_);
159	}	317	}
160		318
161	=back	319	=back
162		320
163	# dynamic methods	321	# dynamic methods
164		322
165	=head2 PROCESS METHODS	323	=head2 COROUTINE METHODS
166		324
167	These are the methods you can call on process objects.	325	These are the methods you can call on coroutine objects.
168		326
169	=over 4	327	=over 4
170		328
171	=item new Coro \⊂	329	=item new Coro \&sub [, @args...]
172		330
173	Create a new process and return it. When the sub returns the process	331	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	332	automatically terminates as if C<terminate> with the returned values were
		333	called. To make the coroutine run you must first put it into the ready queue
175	the ready queue by calling the ready method.	334	by calling the ready method.
176		335
		336	See C<async> for additional discussion.
		337
177	=cut	338	=cut
		339
		340	sub _run_coro {
		341	terminate &{+shift};
		342	}
178		343
179	sub new {	344	sub new {
180	my $class = shift;	345	my $class = shift;
		346
		347	$class->SUPER::new (\&_run_coro, @_)
		348	}
		349
		350	=item $success = $coroutine->ready
		351
		352	Put the given coroutine into the ready queue (according to it's priority)
		353	and return true. If the coroutine is already in the ready queue, do nothing
		354	and return false.
		355
		356	=item $is_ready = $coroutine->is_ready
		357
		358	Return wether the coroutine is currently the ready queue or not,
		359
		360	=item $coroutine->cancel (arg...)
		361
		362	Terminates the given coroutine and makes it return the given arguments as
		363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
		365
		366	=cut
		367
		368	sub cancel {
		369	my $self = shift;
		370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
		373	push @destroy, $self;
		374	$manager->ready;
		375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
		379	}
		380
		381	=item $coroutine->join
		382
		383	Wait until the coroutine terminates and return any values given to the
		384	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		385	from multiple coroutine.
		386
		387	=cut
		388
		389	sub join {
		390	my $self = shift;
		391
		392	unless ($self->{status}) {
		393	my $current = $current;
		394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
		401	}
		402
		403	wantarray ? @{$self->{status}} : $self->{status}[0];
		404	}
		405
		406	=item $coroutine->on_destroy (\&cb)
		407
		408	Registers a callback that is called when this coroutine gets destroyed,
		409	but before it is joined. The callback gets passed the terminate arguments,
		410	if any.
		411
		412	=cut
		413
		414	sub on_destroy {
		415	my ($self, $cb) = @_;
		416
		417	push @{ $self->{destroy_cb} }, $cb;
		418	}
		419
		420	=item $oldprio = $coroutine->prio ($newprio)
		421
		422	Sets (or gets, if the argument is missing) the priority of the
		423	coroutine. Higher priority coroutines get run before lower priority
		424	coroutines. Priorities are small signed integers (currently -4 .. +3),
		425	that you can refer to using PRIO_xxx constants (use the import tag :prio
		426	to get then):
		427
		428	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		429	3 > 1 > 0 > -1 > -3 > -4
		430
		431	# set priority to HIGH
		432	current->prio(PRIO_HIGH);
		433
		434	The idle coroutine ($Coro::idle) always has a lower priority than any
		435	existing coroutine.
		436
		437	Changing the priority of the current coroutine will take effect immediately,
		438	but changing the priority of coroutines in the ready queue (but not
		439	running) will only take effect after the next schedule (of that
		440	coroutine). This is a bug that will be fixed in some future version.
		441
		442	=item $newprio = $coroutine->nice ($change)
		443
		444	Similar to C<prio>, but subtract the given value from the priority (i.e.
		445	higher values mean lower priority, just as in unix).
		446
		447	=item $olddesc = $coroutine->desc ($newdesc)
		448
		449	Sets (or gets in case the argument is missing) the description for this
		450	coroutine. This is just a free-form string you can associate with a coroutine.
		451
		452	=cut
		453
		454	sub desc {
181	my $proc = $_[0];	455	my $old = $_[0]{desc};
182	bless {	456	$_[0]{desc} = $_[1] if @_ > 1;
183	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	457	$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	}	458	}
196		459
197	=back	460	=back
198		461
		462	=head2 GLOBAL FUNCTIONS
		463
		464	=over 4
		465
		466	=item Coro::nready
		467
		468	Returns the number of coroutines that are currently in the ready state,
		469	i.e. that can be switched to. The value C<0> means that the only runnable
		470	coroutine is the currently running one, so C<cede> would have no effect,
		471	and C<schedule> would cause a deadlock unless there is an idle handler
		472	that wakes up some coroutines.
		473
		474	=item my $guard = Coro::guard { ... }
		475
		476	This creates and returns a guard object. Nothing happens until the object
		477	gets destroyed, in which case the codeblock given as argument will be
		478	executed. This is useful to free locks or other resources in case of a
		479	runtime error or when the coroutine gets canceled, as in both cases the
		480	guard block will be executed. The guard object supports only one method,
		481	C<< ->cancel >>, which will keep the codeblock from being executed.
		482
		483	Example: set some flag and clear it again when the coroutine gets canceled
		484	or the function returns:
		485
		486	sub do_something {
		487	my $guard = Coro::guard { $busy = 0 };
		488	$busy = 1;
		489
		490	# do something that requires $busy to be true
		491	}
		492
		493	=cut
		494
		495	sub guard(&) {
		496	bless \(my $cb = $_[0]), "Coro::guard"
		497	}
		498
		499	sub Coro::guard::cancel {
		500	${$_[0]} = sub { };
		501	}
		502
		503	sub Coro::guard::DESTROY {
		504	${$_[0]}->();
		505	}
		506
		507
		508	=item unblock_sub { ... }
		509
		510	This utility function takes a BLOCK or code reference and "unblocks" it,
		511	returning the new coderef. This means that the new coderef will return
		512	immediately without blocking, returning nothing, while the original code
		513	ref will be called (with parameters) from within its own coroutine.
		514
		515	The reason this function exists is that many event libraries (such as the
		516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		517	of thread-safety). This means you must not block within event callbacks,
		518	otherwise you might suffer from crashes or worse.
		519
		520	This function allows your callbacks to block by executing them in another
		521	coroutine where it is safe to block. One example where blocking is handy
		522	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		523	disk.
		524
		525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		526	creating event callbacks that want to block.
		527
		528	=cut
		529
		530	our @unblock_queue;
		531
		532	# we create a special coro because we want to cede,
		533	# to reduce pressure on the coro pool (because most callbacks
		534	# return immediately and can be reused) and because we cannot cede
		535	# inside an event callback.
		536	our $unblock_scheduler = new Coro sub {
		537	while () {
		538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
		540	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		541
		542	$coro->{_invoke} = $cb;
		543	$coro->ready;
		544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		545	}
		546	schedule; # sleep well
		547	}
		548	};
		549	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		550
		551	sub unblock_sub(&) {
		552	my $cb = shift;
		553
		554	sub {
		555	unshift @unblock_queue, [$cb, @_];
		556	$unblock_scheduler->ready;
		557	}
		558	}
		559
		560	=back
		561
199	=cut	562	=cut
200		563
201	1;	564	1;
202		565
		566	=head1 BUGS/LIMITATIONS
		567
		568	- you must make very sure that no coro is still active on global
		569	destruction. very bad things might happen otherwise (usually segfaults).
		570
		571	- this module is not thread-safe. You should only ever use this module
		572	from the same thread (this requirement might be loosened in the future
		573	to allow per-thread schedulers, but Coro::State does not yet allow
		574	this).
		575
203	=head1 SEE ALSO	576	=head1 SEE ALSO
204		577
205	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	578	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
206	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	579
		580	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		581
		582	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		583
		584	Embedding: L<Coro:MakeMaker>
207		585
208	=head1 AUTHOR	586	=head1 AUTHOR
209		587
210	Marc Lehmann <pcg@goof.com>	588	Marc Lehmann <schmorp@schmorp.de>
211	http://www.goof.com/pcg/marc/	589	http://home.schmorp.de/
212		590
213	=cut	591	=cut
214		592

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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 1.136 by root, Sat Sep 22 22:59:31 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 1.136 by root, Sat Sep 22 22:59:31 2007 UTC