[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 1.150 by root, Sat Oct 6 01:11:01 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 $VERSION = '4.02';
34	@EXPORT_OK = qw($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->{_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	}	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	See the C<Coro::State::new> constructor for info about the coroutine
		193	environment.
107		194
		195	Calling C<exit> in a coroutine will do the same as calling exit outside
		196	the coroutine. Likewise, when the coroutine dies, the program will exit,
		197	just as it would in the main program.
		198
		199	# create a new coroutine that just prints its arguments
		200	async {
		201	print "@_\n";
		202	} 1,2,3,4;
		203
		204	=cut
		205
108	sub async(&) {	206	sub async(&@) {
109	(new Coro $_[0])->ready;	207	my $coro = new Coro @_;
		208	$coro->ready;
		209	$coro
		210	}
		211
		212	=item async_pool { ... } [@args...]
		213
		214	Similar to C<async>, but uses a coroutine pool, so you should not call
		215	terminate or join (although you are allowed to), and you get a coroutine
		216	that might have executed other code already (which can be good or bad :).
		217
		218	Also, the block is executed in an C<eval> context and a warning will be
		219	issued in case of an exception instead of terminating the program, as
		220	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		221	will not work in the expected way, unless you call terminate or cancel,
		222	which somehow defeats the purpose of pooling.
		223
		224	The priority will be reset to C<0> after each job, tracing will be
		225	disabled, the description will be reset and the default output filehandle
		226	gets restored, so you can change alkl these. Otherwise the coroutine will
		227	be re-used "as-is": most notably if you change other per-coroutine global
		228	stuff such as C<$/> you need to revert that change, which is most simply
		229	done by using local as in C< local $/ >.
		230
		231	The pool size is limited to 8 idle coroutines (this can be adjusted by
		232	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		233	required.
		234
		235	If you are concerned about pooled coroutines growing a lot because a
		236	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		237	{ terminate }> once per second or so to slowly replenish the pool. In
		238	addition to that, when the stacks used by a handler grows larger than 16kb
		239	(adjustable with $Coro::POOL_RSS) it will also exit.
		240
		241	=cut
		242
		243	our $POOL_SIZE = 8;
		244	our $POOL_RSS = 16 * 1024;
		245	our @async_pool;
		246
		247	sub pool_handler {
		248	my $cb;
		249
		250	while () {
		251	eval {
		252	while () {
		253	_pool_1 $cb;
		254	&$cb;
		255	_pool_2 $cb;
		256	&schedule;
		257	}
		258	};
		259
		260	last if $@ eq "\3terminate\2\n";
		261	warn $@ if $@;
		262	}
		263	}
		264
		265	sub async_pool(&@) {
		266	# this is also inlined into the unlock_scheduler
		267	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		268
		269	$coro->{_invoke} = [@_];
		270	$coro->ready;
		271
		272	$coro
110	}	273	}
111		274
112	=item schedule	275	=item schedule
113		276
114	Calls the scheduler. Please note that the current process will not be put	277	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	278	into the ready queue, so calling this function usually means you will
116	never be called again.	279	never be called again unless something else (e.g. an event handler) calls
		280	ready.
117		281
118	=cut	282	The canonical way to wait on external events is this:
119		283
120	my $prev;	284	{
		285	# remember current coroutine
		286	my $current = $Coro::current;
121		287
122	sub schedule {	288	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	289	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	290	# 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;	291	$current->ready;
136	&schedule;	292	undef $current;
137	}	293	};
138		294
		295	# call schedule until event occurred.
		296	# in case we are woken up for other reasons
		297	# (current still defined), loop.
		298	Coro::schedule while $current;
		299	}
		300
		301	=item cede
		302
		303	"Cede" to other coroutines. This function puts the current coroutine into the
		304	ready queue and calls C<schedule>, which has the effect of giving up the
		305	current "timeslice" to other coroutines of the same or higher priority.
		306
		307	Returns true if at least one coroutine switch has happened.
		308
		309	=item Coro::cede_notself
		310
		311	Works like cede, but is not exported by default and will cede to any
		312	coroutine, regardless of priority, once.
		313
		314	Returns true if at least one coroutine switch has happened.
		315
139	=item terminate	316	=item terminate [arg...]
140		317
141	Terminates the current process.	318	Terminates the current coroutine with the given status values (see L<cancel>).
		319
		320	=item killall
		321
		322	Kills/terminates/cancels all coroutines except the currently running
		323	one. This is useful after a fork, either in the child or the parent, as
		324	usually only one of them should inherit the running coroutines.
142		325
143	=cut	326	=cut
144		327
145	sub terminate {	328	sub terminate {
146	&schedule;	329	$current->cancel (@_);
		330	}
		331
		332	sub killall {
		333	for (Coro::State::list) {
		334	$_->cancel
		335	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		336	}
147	}	337	}
148		338
149	=back	339	=back
150		340
151	# dynamic methods	341	# dynamic methods
152		342
153	=head2 PROCESS METHODS	343	=head2 COROUTINE METHODS
154		344
155	These are the methods you can call on process objects.	345	These are the methods you can call on coroutine objects.
156		346
157	=over 4	347	=over 4
158		348
159	=item new Coro \⊂	349	=item new Coro \&sub [, @args...]
160		350
161	Create a new process and return it. When the sub returns the process	351	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	352	automatically terminates as if C<terminate> with the returned values were
		353	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	354	by calling the ready method.
164		355
		356	See C<async> and C<Coro::State::new> for additional info about the
		357	coroutine environment.
		358
165	=cut	359	=cut
		360
		361	sub _run_coro {
		362	terminate &{+shift};
		363	}
166		364
167	sub new {	365	sub new {
168	my $class = shift;	366	my $class = shift;
		367
		368	$class->SUPER::new (\&_run_coro, @_)
		369	}
		370
		371	=item $success = $coroutine->ready
		372
		373	Put the given coroutine into the ready queue (according to it's priority)
		374	and return true. If the coroutine is already in the ready queue, do nothing
		375	and return false.
		376
		377	=item $is_ready = $coroutine->is_ready
		378
		379	Return wether the coroutine is currently the ready queue or not,
		380
		381	=item $coroutine->cancel (arg...)
		382
		383	Terminates the given coroutine and makes it return the given arguments as
		384	status (default: the empty list). Never returns if the coroutine is the
		385	current coroutine.
		386
		387	=cut
		388
		389	sub cancel {
		390	my $self = shift;
		391	$self->{_status} = [@_];
		392
		393	if ($current == $self) {
		394	push @destroy, $self;
		395	$manager->ready;
		396	&schedule while 1;
		397	} else {
		398	$self->_cancel;
		399	}
		400	}
		401
		402	=item $coroutine->join
		403
		404	Wait until the coroutine terminates and return any values given to the
		405	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		406	from multiple coroutines.
		407
		408	=cut
		409
		410	sub join {
		411	my $self = shift;
		412
		413	unless ($self->{_status}) {
		414	my $current = $current;
		415
		416	push @{$self->{_on_destroy}}, sub {
		417	$current->ready;
		418	undef $current;
		419	};
		420
		421	&schedule while $current;
		422	}
		423
		424	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		425	}
		426
		427	=item $coroutine->on_destroy (\&cb)
		428
		429	Registers a callback that is called when this coroutine gets destroyed,
		430	but before it is joined. The callback gets passed the terminate arguments,
		431	if any.
		432
		433	=cut
		434
		435	sub on_destroy {
		436	my ($self, $cb) = @_;
		437
		438	push @{ $self->{_on_destroy} }, $cb;
		439	}
		440
		441	=item $oldprio = $coroutine->prio ($newprio)
		442
		443	Sets (or gets, if the argument is missing) the priority of the
		444	coroutine. Higher priority coroutines get run before lower priority
		445	coroutines. Priorities are small signed integers (currently -4 .. +3),
		446	that you can refer to using PRIO_xxx constants (use the import tag :prio
		447	to get then):
		448
		449	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		450	3 > 1 > 0 > -1 > -3 > -4
		451
		452	# set priority to HIGH
		453	current->prio(PRIO_HIGH);
		454
		455	The idle coroutine ($Coro::idle) always has a lower priority than any
		456	existing coroutine.
		457
		458	Changing the priority of the current coroutine will take effect immediately,
		459	but changing the priority of coroutines in the ready queue (but not
		460	running) will only take effect after the next schedule (of that
		461	coroutine). This is a bug that will be fixed in some future version.
		462
		463	=item $newprio = $coroutine->nice ($change)
		464
		465	Similar to C<prio>, but subtract the given value from the priority (i.e.
		466	higher values mean lower priority, just as in unix).
		467
		468	=item $olddesc = $coroutine->desc ($newdesc)
		469
		470	Sets (or gets in case the argument is missing) the description for this
		471	coroutine. This is just a free-form string you can associate with a coroutine.
		472
		473	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		474	can modify this member directly if you wish.
		475
		476	=item $coroutine->throw ([$scalar])
		477
		478	If C<$throw> is specified and defined, it will be thrown as an exception
		479	inside the coroutine at the next convinient point in time (usually after
		480	it gains control at the next schedule/transfer/cede). Otherwise clears the
		481	exception object.
		482
		483	The exception object will be thrown "as is" with the specified scalar in
		484	C<$@>, i.e. if it is a string, no line number or newline will be appended
		485	(unlike with C<die>).
		486
		487	This can be used as a softer means than C<cancel> to ask a coroutine to
		488	end itself, although there is no guarentee that the exception will lead to
		489	termination, and if the exception isn't caught it might well end the whole
		490	program.
		491
		492	=cut
		493
		494	sub desc {
169	my $proc = $_[0];	495	my $old = $_[0]{desc};
170	bless {	496	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	497	$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	}	498	}
184		499
185	=back	500	=back
186		501
		502	=head2 GLOBAL FUNCTIONS
		503
		504	=over 4
		505
		506	=item Coro::nready
		507
		508	Returns the number of coroutines that are currently in the ready state,
		509	i.e. that can be switched to. The value C<0> means that the only runnable
		510	coroutine is the currently running one, so C<cede> would have no effect,
		511	and C<schedule> would cause a deadlock unless there is an idle handler
		512	that wakes up some coroutines.
		513
		514	=item my $guard = Coro::guard { ... }
		515
		516	This creates and returns a guard object. Nothing happens until the object
		517	gets destroyed, in which case the codeblock given as argument will be
		518	executed. This is useful to free locks or other resources in case of a
		519	runtime error or when the coroutine gets canceled, as in both cases the
		520	guard block will be executed. The guard object supports only one method,
		521	C<< ->cancel >>, which will keep the codeblock from being executed.
		522
		523	Example: set some flag and clear it again when the coroutine gets canceled
		524	or the function returns:
		525
		526	sub do_something {
		527	my $guard = Coro::guard { $busy = 0 };
		528	$busy = 1;
		529
		530	# do something that requires $busy to be true
		531	}
		532
		533	=cut
		534
		535	sub guard(&) {
		536	bless \(my $cb = $_[0]), "Coro::guard"
		537	}
		538
		539	sub Coro::guard::cancel {
		540	${$_[0]} = sub { };
		541	}
		542
		543	sub Coro::guard::DESTROY {
		544	${$_[0]}->();
		545	}
		546
		547
		548	=item unblock_sub { ... }
		549
		550	This utility function takes a BLOCK or code reference and "unblocks" it,
		551	returning the new coderef. This means that the new coderef will return
		552	immediately without blocking, returning nothing, while the original code
		553	ref will be called (with parameters) from within its own coroutine.
		554
		555	The reason this function exists is that many event libraries (such as the
		556	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		557	of thread-safety). This means you must not block within event callbacks,
		558	otherwise you might suffer from crashes or worse.
		559
		560	This function allows your callbacks to block by executing them in another
		561	coroutine where it is safe to block. One example where blocking is handy
		562	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		563	disk.
		564
		565	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		566	creating event callbacks that want to block.
		567
		568	=cut
		569
		570	our @unblock_queue;
		571
		572	# we create a special coro because we want to cede,
		573	# to reduce pressure on the coro pool (because most callbacks
		574	# return immediately and can be reused) and because we cannot cede
		575	# inside an event callback.
		576	our $unblock_scheduler = new Coro sub {
		577	while () {
		578	while (my $cb = pop @unblock_queue) {
		579	# this is an inlined copy of async_pool
		580	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		581
		582	$coro->{_invoke} = $cb;
		583	$coro->ready;
		584	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		585	}
		586	schedule; # sleep well
		587	}
		588	};
		589	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		590
		591	sub unblock_sub(&) {
		592	my $cb = shift;
		593
		594	sub {
		595	unshift @unblock_queue, [$cb, @_];
		596	$unblock_scheduler->ready;
		597	}
		598	}
		599
		600	=back
		601
187	=cut	602	=cut
188		603
189	1;	604	1;
190		605
		606	=head1 BUGS/LIMITATIONS
		607
		608	- you must make very sure that no coro is still active on global
		609	destruction. very bad things might happen otherwise (usually segfaults).
		610
		611	- this module is not thread-safe. You should only ever use this module
		612	from the same thread (this requirement might be loosened in the future
		613	to allow per-thread schedulers, but Coro::State does not yet allow
		614	this).
		615
		616	=head1 SEE ALSO
		617
		618	Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		619
		620	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		621
		622	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		623
		624	Embedding: L<Coro:MakeMaker>
		625
191	=head1 AUTHOR	626	=head1 AUTHOR
192		627
193	Marc Lehmann <pcg@goof.com>	628	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	629	http://home.schmorp.de/
195		630
196	=cut	631	=cut
197		632

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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 1.150 by root, Sat Oct 6 01:11:01 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 1.150 by root, Sat Oct 6 01:11:01 2007 UTC