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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC

…		…
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
		15	print "1\n";
		16	cede; # yield to coroutine
		17	print "3\n";
		18	cede; # and again
12		19
13	# alternatively create an async process like this:	20	# use locking
		21	my $lock = new Coro::Semaphore;
		22	my $locked;
14		23
15	sub some_func : Coro {	24	$lock->down;
16	# some more async code	25	$locked = 1;
17	}	26	$lock->up;
18
19	yield;
20		27
21	=head1 DESCRIPTION	28	=head1 DESCRIPTION
22		29
		30	This module collection manages coroutines. Coroutines are similar
		31	to threads but don't run in parallel at the same time even on SMP
		32	machines. The specific flavor of coroutine used in this module also
		33	guarantees you that it will not switch between coroutines unless
		34	necessary, at easily-identified points in your program, so locking and
		35	parallel access are rarely an issue, making coroutine programming much
		36	safer than threads programming.
		37
		38	(Perl, however, does not natively support real threads but instead does a
		39	very slow and memory-intensive emulation of processes using threads. This
		40	is a performance win on Windows machines, and a loss everywhere else).
		41
		42	In this module, coroutines are defined as "callchain + lexical variables +
		43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
		44	its own set of lexicals and its own set of perls most important global
		45	variables (see L<Coro::State> for more configuration).
		46
23	=cut	47	=cut
24		48
25	package Coro;	49	package Coro;
26		50
		51	use strict;
		52	no warnings "uninitialized";
		53
27	use Coro::State;	54	use Coro::State;
28		55
29	use base Exporter;	56	use base qw(Coro::State Exporter);
30		57
31	$VERSION = 0.03;	58	our $idle; # idle handler
		59	our $main; # main coroutine
		60	our $current; # current coroutine
32		61
33	@EXPORT = qw(async yield schedule);	62	our $VERSION = '4.51';
34	@EXPORT_OK = qw($current);	63
		64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
		65	our %EXPORT_TAGS = (
		66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		67	);
		68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
35		69
36	{	70	{
37	use subs 'async';
38
39	my @async;	71	my @async;
		72	my $init;
40		73
41	# this way of handling attributes simply is NOT scalable ;()	74	# this way of handling attributes simply is NOT scalable ;()
42	sub import {	75	sub import {
		76	no strict 'refs';
		77
43	Coro->export_to_level(1, @_);	78	Coro->export_to_level (1, @_);
		79
44	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	80	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
45	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	81	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
46	my ($package, $ref) = (shift, shift);	82	my ($package, $ref) = (shift, shift);
47	my @attrs;	83	my @attrs;
48	for (@_) {	84	for (@_) {
49	if ($_ eq "Coro") {	85	if ($_ eq "Coro") {
50	push @async, $ref;	86	push @async, $ref;
		87	unless ($init++) {
		88	eval q{
		89	sub INIT {
		90	&async(pop @async) while @async;
		91	}
		92	};
		93	}
51	} else {	94	} else {
52	push @attrs, @_;	95	push @attrs, $_;
53	}	96	}
54	}	97	}
55	return $old ? $old->($package, $name, @attrs) : @attrs;	98	return $old ? $old->($package, $ref, @attrs) : @attrs;
56	};	99	};
57	}	100	}
58		101
59	sub INIT {
60	async pop @async while @async;
61	}
62	}	102	}
63		103
64	my $idle = new Coro sub {	104	=over 4
65	&yield while 1;	105
		106	=item $main
		107
		108	This coroutine represents the main program.
		109
		110	=cut
		111
		112	$main = new Coro;
		113
		114	=item $current (or as function: current)
		115
		116	The current coroutine (the last coroutine switched to). The initial value
		117	is C<$main> (of course).
		118
		119	This variable is B<strictly> I<read-only>. It is provided for performance
		120	reasons. If performance is not essential you are encouraged to use the
		121	C<Coro::current> function instead.
		122
		123	=cut
		124
		125	$main->{desc} = "[main::]";
		126
		127	# maybe some other module used Coro::Specific before...
		128	$main->{_specific} = $current->{_specific}
		129	if $current;
		130
		131	_set_current $main;
		132
		133	sub current() { $current }
		134
		135	=item $idle
		136
		137	A callback that is called whenever the scheduler finds no ready coroutines
		138	to run. The default implementation prints "FATAL: deadlock detected" and
		139	exits, because the program has no other way to continue.
		140
		141	This hook is overwritten by modules such as C<Coro::Timer> and
		142	C<Coro::Event> to wait on an external event that hopefully wake up a
		143	coroutine so the scheduler can run it.
		144
		145	Please note that if your callback recursively invokes perl (e.g. for event
		146	handlers), then it must be prepared to be called recursively itself.
		147
		148	=cut
		149
		150	$idle = sub {
		151	require Carp;
		152	Carp::croak ("FATAL: deadlock detected");
66	};	153	};
67		154
68	=item $main	155	sub _cancel {
		156	my ($self) = @_;
69		157
70	This coroutine represents the main program.	158	# free coroutine data and mark as destructed
		159	$self->_destroy
		160	or return;
71		161
72	=cut	162	# call all destruction callbacks
73		163	$_->(@{$self->{_status}})
74	$main = new Coro;	164	for @{(delete $self->{_on_destroy}) \|\| []};
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	}	165	}
86		166
87	$current = $main;	167	# this coroutine is necessary because a coroutine
		168	# cannot destroy itself.
		169	my @destroy;
		170	my $manager;
88		171
89	# we really need priorities...	172	$manager = new Coro sub {
90	my @ready = (); # the ready queue. hehe, rather broken ;)	173	while () {
		174	(shift @destroy)->_cancel
		175	while @destroy;
91		176
92	# static methods. not really.	177	&schedule;
		178	}
		179	};
		180	$manager->desc ("[coro manager]");
		181	$manager->prio (PRIO_MAX);
		182
		183	=back
93		184
94	=head2 STATIC METHODS	185	=head2 STATIC METHODS
95		186
96	Static methods are actually functions that operate on the current process only.	187	Static methods are actually functions that operate on the current coroutine only.
97		188
98	=over 4	189	=over 4
99		190
100	=item async { ... };	191	=item async { ... } [@args...]
101		192
102	Create a new asynchronous process and return it's process object	193	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	194	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	195	terminated.
105		196
106	=cut	197	See the C<Coro::State::new> constructor for info about the coroutine
		198	environment in which coroutines run.
107		199
		200	Calling C<exit> in a coroutine will do the same as calling exit outside
		201	the coroutine. Likewise, when the coroutine dies, the program will exit,
		202	just as it would in the main program.
		203
		204	# create a new coroutine that just prints its arguments
		205	async {
		206	print "@_\n";
		207	} 1,2,3,4;
		208
		209	=cut
		210
108	sub async(&) {	211	sub async(&@) {
109	(new Coro $_[0])->ready;	212	my $coro = new Coro @_;
		213	$coro->ready;
		214	$coro
		215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join (although you are allowed to), and you get a coroutine
		221	that might have executed other code already (which can be good or bad :).
		222
		223	Also, the block is executed in an C<eval> context and a warning will be
		224	issued in case of an exception instead of terminating the program, as
		225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		226	will not work in the expected way, unless you call terminate or cancel,
		227	which somehow defeats the purpose of pooling.
		228
		229	The priority will be reset to C<0> after each job, tracing will be
		230	disabled, the description will be reset and the default output filehandle
		231	gets restored, so you can change alkl these. Otherwise the coroutine will
		232	be re-used "as-is": most notably if you change other per-coroutine global
		233	stuff such as C<$/> you need to revert that change, which is most simply
		234	done by using local as in C< local $/ >.
		235
		236	The pool size is limited to 8 idle coroutines (this can be adjusted by
		237	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		238	required.
		239
		240	If you are concerned about pooled coroutines growing a lot because a
		241	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		242	{ terminate }> once per second or so to slowly replenish the pool. In
		243	addition to that, when the stacks used by a handler grows larger than 16kb
		244	(adjustable with $Coro::POOL_RSS) it will also exit.
		245
		246	=cut
		247
		248	our $POOL_SIZE = 8;
		249	our $POOL_RSS = 16 * 1024;
		250	our @async_pool;
		251
		252	sub pool_handler {
		253	my $cb;
		254
		255	while () {
		256	eval {
		257	while () {
		258	_pool_1 $cb;
		259	&$cb;
		260	_pool_2 $cb;
		261	&schedule;
		262	}
		263	};
		264
		265	last if $@ eq "\3async_pool terminate\2\n";
		266	warn $@ if $@;
		267	}
		268	}
		269
		270	sub async_pool(&@) {
		271	# this is also inlined into the unlock_scheduler
		272	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		273
		274	$coro->{_invoke} = [@_];
		275	$coro->ready;
		276
		277	$coro
110	}	278	}
111		279
112	=item schedule	280	=item schedule
113		281
114	Calls the scheduler. Please note that the current process will not be put	282	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	283	into the ready queue, so calling this function usually means you will
116	never be called again.	284	never be called again unless something else (e.g. an event handler) calls
		285	ready.
117		286
118	=cut	287	The canonical way to wait on external events is this:
119		288
120	my $prev;	289	{
		290	# remember current coroutine
		291	my $current = $Coro::current;
121		292
122	sub schedule {	293	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	294	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	295	# 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;	296	$current->ready;
136	&schedule;	297	undef $current;
137	}	298	};
138		299
		300	# call schedule until event occurred.
		301	# in case we are woken up for other reasons
		302	# (current still defined), loop.
		303	Coro::schedule while $current;
		304	}
		305
		306	=item cede
		307
		308	"Cede" to other coroutines. This function puts the current coroutine into the
		309	ready queue and calls C<schedule>, which has the effect of giving up the
		310	current "timeslice" to other coroutines of the same or higher priority.
		311
		312	=item Coro::cede_notself
		313
		314	Works like cede, but is not exported by default and will cede to any
		315	coroutine, regardless of priority, once.
		316
139	=item terminate	317	=item terminate [arg...]
140		318
141	Terminates the current process.	319	Terminates the current coroutine with the given status values (see L<cancel>).
		320
		321	=item killall
		322
		323	Kills/terminates/cancels all coroutines except the currently running
		324	one. This is useful after a fork, either in the child or the parent, as
		325	usually only one of them should inherit the running coroutines.
142		326
143	=cut	327	=cut
144		328
145	sub terminate {	329	sub terminate {
146	&schedule;	330	$current->cancel (@_);
		331	}
		332
		333	sub killall {
		334	for (Coro::State::list) {
		335	$_->cancel
		336	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		337	}
147	}	338	}
148		339
149	=back	340	=back
150		341
151	# dynamic methods
152
153	=head2 PROCESS METHODS	342	=head2 COROUTINE METHODS
154		343
155	These are the methods you can call on process objects.	344	These are the methods you can call on coroutine objects.
156		345
157	=over 4	346	=over 4
158		347
159	=item new Coro \⊂	348	=item new Coro \&sub [, @args...]
160		349
161	Create a new process and return it. When the sub returns the process	350	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	351	automatically terminates as if C<terminate> with the returned values were
		352	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	353	by calling the ready method.
164		354
		355	See C<async> and C<Coro::State::new> for additional info about the
		356	coroutine environment.
		357
165	=cut	358	=cut
		359
		360	sub _run_coro {
		361	terminate &{+shift};
		362	}
166		363
167	sub new {	364	sub new {
168	my $class = shift;	365	my $class = shift;
		366
		367	$class->SUPER::new (\&_run_coro, @_)
		368	}
		369
		370	=item $success = $coroutine->ready
		371
		372	Put the given coroutine into the ready queue (according to it's priority)
		373	and return true. If the coroutine is already in the ready queue, do nothing
		374	and return false.
		375
		376	=item $is_ready = $coroutine->is_ready
		377
		378	Return wether the coroutine is currently the ready queue or not,
		379
		380	=item $coroutine->cancel (arg...)
		381
		382	Terminates the given coroutine and makes it return the given arguments as
		383	status (default: the empty list). Never returns if the coroutine is the
		384	current coroutine.
		385
		386	=cut
		387
		388	sub cancel {
		389	my $self = shift;
		390	$self->{_status} = [@_];
		391
		392	if ($current == $self) {
		393	push @destroy, $self;
		394	$manager->ready;
		395	&schedule while 1;
		396	} else {
		397	$self->_cancel;
		398	}
		399	}
		400
		401	=item $coroutine->join
		402
		403	Wait until the coroutine terminates and return any values given to the
		404	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		405	from multiple coroutines.
		406
		407	=cut
		408
		409	sub join {
		410	my $self = shift;
		411
		412	unless ($self->{_status}) {
		413	my $current = $current;
		414
		415	push @{$self->{_on_destroy}}, sub {
		416	$current->ready;
		417	undef $current;
		418	};
		419
		420	&schedule while $current;
		421	}
		422
		423	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		424	}
		425
		426	=item $coroutine->on_destroy (\&cb)
		427
		428	Registers a callback that is called when this coroutine gets destroyed,
		429	but before it is joined. The callback gets passed the terminate arguments,
		430	if any.
		431
		432	=cut
		433
		434	sub on_destroy {
		435	my ($self, $cb) = @_;
		436
		437	push @{ $self->{_on_destroy} }, $cb;
		438	}
		439
		440	=item $oldprio = $coroutine->prio ($newprio)
		441
		442	Sets (or gets, if the argument is missing) the priority of the
		443	coroutine. Higher priority coroutines get run before lower priority
		444	coroutines. Priorities are small signed integers (currently -4 .. +3),
		445	that you can refer to using PRIO_xxx constants (use the import tag :prio
		446	to get then):
		447
		448	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		449	3 > 1 > 0 > -1 > -3 > -4
		450
		451	# set priority to HIGH
		452	current->prio(PRIO_HIGH);
		453
		454	The idle coroutine ($Coro::idle) always has a lower priority than any
		455	existing coroutine.
		456
		457	Changing the priority of the current coroutine will take effect immediately,
		458	but changing the priority of coroutines in the ready queue (but not
		459	running) will only take effect after the next schedule (of that
		460	coroutine). This is a bug that will be fixed in some future version.
		461
		462	=item $newprio = $coroutine->nice ($change)
		463
		464	Similar to C<prio>, but subtract the given value from the priority (i.e.
		465	higher values mean lower priority, just as in unix).
		466
		467	=item $olddesc = $coroutine->desc ($newdesc)
		468
		469	Sets (or gets in case the argument is missing) the description for this
		470	coroutine. This is just a free-form string you can associate with a coroutine.
		471
		472	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		473	can modify this member directly if you wish.
		474
		475	=item $coroutine->throw ([$scalar])
		476
		477	If C<$throw> is specified and defined, it will be thrown as an exception
		478	inside the coroutine at the next convinient point in time (usually after
		479	it gains control at the next schedule/transfer/cede). Otherwise clears the
		480	exception object.
		481
		482	The exception object will be thrown "as is" with the specified scalar in
		483	C<$@>, i.e. if it is a string, no line number or newline will be appended
		484	(unlike with C<die>).
		485
		486	This can be used as a softer means than C<cancel> to ask a coroutine to
		487	end itself, although there is no guarentee that the exception will lead to
		488	termination, and if the exception isn't caught it might well end the whole
		489	program.
		490
		491	=cut
		492
		493	sub desc {
169	my $proc = $_[0];	494	my $old = $_[0]{desc};
170	bless {	495	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	496	$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	}	497	}
184		498
185	=back	499	=back
186		500
		501	=head2 GLOBAL FUNCTIONS
		502
		503	=over 4
		504
		505	=item Coro::nready
		506
		507	Returns the number of coroutines that are currently in the ready state,
		508	i.e. that can be switched to. The value C<0> means that the only runnable
		509	coroutine is the currently running one, so C<cede> would have no effect,
		510	and C<schedule> would cause a deadlock unless there is an idle handler
		511	that wakes up some coroutines.
		512
		513	=item my $guard = Coro::guard { ... }
		514
		515	This creates and returns a guard object. Nothing happens until the object
		516	gets destroyed, in which case the codeblock given as argument will be
		517	executed. This is useful to free locks or other resources in case of a
		518	runtime error or when the coroutine gets canceled, as in both cases the
		519	guard block will be executed. The guard object supports only one method,
		520	C<< ->cancel >>, which will keep the codeblock from being executed.
		521
		522	Example: set some flag and clear it again when the coroutine gets canceled
		523	or the function returns:
		524
		525	sub do_something {
		526	my $guard = Coro::guard { $busy = 0 };
		527	$busy = 1;
		528
		529	# do something that requires $busy to be true
		530	}
		531
		532	=cut
		533
		534	sub guard(&) {
		535	bless \(my $cb = $_[0]), "Coro::guard"
		536	}
		537
		538	sub Coro::guard::cancel {
		539	${$_[0]} = sub { };
		540	}
		541
		542	sub Coro::guard::DESTROY {
		543	${$_[0]}->();
		544	}
		545
		546
		547	=item unblock_sub { ... }
		548
		549	This utility function takes a BLOCK or code reference and "unblocks" it,
		550	returning the new coderef. This means that the new coderef will return
		551	immediately without blocking, returning nothing, while the original code
		552	ref will be called (with parameters) from within its own coroutine.
		553
		554	The reason this function exists is that many event libraries (such as the
		555	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		556	of thread-safety). This means you must not block within event callbacks,
		557	otherwise you might suffer from crashes or worse.
		558
		559	This function allows your callbacks to block by executing them in another
		560	coroutine where it is safe to block. One example where blocking is handy
		561	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		562	disk.
		563
		564	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		565	creating event callbacks that want to block.
		566
		567	=cut
		568
		569	our @unblock_queue;
		570
		571	# we create a special coro because we want to cede,
		572	# to reduce pressure on the coro pool (because most callbacks
		573	# return immediately and can be reused) and because we cannot cede
		574	# inside an event callback.
		575	our $unblock_scheduler = new Coro sub {
		576	while () {
		577	while (my $cb = pop @unblock_queue) {
		578	# this is an inlined copy of async_pool
		579	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		580
		581	$coro->{_invoke} = $cb;
		582	$coro->ready;
		583	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		584	}
		585	schedule; # sleep well
		586	}
		587	};
		588	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		589
		590	sub unblock_sub(&) {
		591	my $cb = shift;
		592
		593	sub {
		594	unshift @unblock_queue, [$cb, @_];
		595	$unblock_scheduler->ready;
		596	}
		597	}
		598
		599	=back
		600
187	=cut	601	=cut
188		602
189	1;	603	1;
190		604
		605	=head1 BUGS/LIMITATIONS
		606
		607	- you must make very sure that no coro is still active on global
		608	destruction. very bad things might happen otherwise (usually segfaults).
		609
		610	- this module is not thread-safe. You should only ever use this module
		611	from the same thread (this requirement might be loosened in the future
		612	to allow per-thread schedulers, but Coro::State does not yet allow
		613	this).
		614
		615	=head1 SEE ALSO
		616
		617	Lower level Configuration, Coroutine Environment: L<Coro::State>.
		618
		619	Debugging: L<Coro::Debug>.
		620
		621	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
		622
		623	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		624
		625	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
		626
		627	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
		628
		629	Embedding: L<Coro::MakeMaker>.
		630
191	=head1 AUTHOR	631	=head1 AUTHOR
192		632
193	Marc Lehmann <pcg@goof.com>	633	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	634	http://home.schmorp.de/
195		635
196	=cut	636	=cut
197		637

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs. Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC