[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 1.165 by root, Thu Dec 20 07:29:14 2007 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 $VERSION = '4.34';
34	@EXPORT_OK = qw($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;
		176
		177	&schedule;
		178	}
		179	};
		180	$manager->desc ("[coro manager]");
		181	$manager->prio (PRIO_MAX);
91		182
92	# static methods. not really.	183	# static methods. not really.
93		184
		185	=back
		186
94	=head2 STATIC METHODS	187	=head2 STATIC METHODS
95		188
96	Static methods are actually functions that operate on the current process only.	189	Static methods are actually functions that operate on the current coroutine only.
97		190
98	=over 4	191	=over 4
99		192
100	=item async { ... };	193	=item async { ... } [@args...]
101		194
102	Create a new asynchronous process and return it's process object	195	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	196	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	197	terminated.
105		198
106	=cut	199	See the C<Coro::State::new> constructor for info about the coroutine
		200	environment in which coroutines run.
107		201
		202	Calling C<exit> in a coroutine will do the same as calling exit outside
		203	the coroutine. Likewise, when the coroutine dies, the program will exit,
		204	just as it would in the main program.
		205
		206	# create a new coroutine that just prints its arguments
		207	async {
		208	print "@_\n";
		209	} 1,2,3,4;
		210
		211	=cut
		212
108	sub async(&) {	213	sub async(&@) {
109	(new Coro $_[0])->ready;	214	my $coro = new Coro @_;
		215	$coro->ready;
		216	$coro
		217	}
		218
		219	=item async_pool { ... } [@args...]
		220
		221	Similar to C<async>, but uses a coroutine pool, so you should not call
		222	terminate or join (although you are allowed to), and you get a coroutine
		223	that might have executed other code already (which can be good or bad :).
		224
		225	Also, the block is executed in an C<eval> context and a warning will be
		226	issued in case of an exception instead of terminating the program, as
		227	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		228	will not work in the expected way, unless you call terminate or cancel,
		229	which somehow defeats the purpose of pooling.
		230
		231	The priority will be reset to C<0> after each job, tracing will be
		232	disabled, the description will be reset and the default output filehandle
		233	gets restored, so you can change alkl these. Otherwise the coroutine will
		234	be re-used "as-is": most notably if you change other per-coroutine global
		235	stuff such as C<$/> you need to revert that change, which is most simply
		236	done by using local as in C< local $/ >.
		237
		238	The pool size is limited to 8 idle coroutines (this can be adjusted by
		239	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		240	required.
		241
		242	If you are concerned about pooled coroutines growing a lot because a
		243	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		244	{ terminate }> once per second or so to slowly replenish the pool. In
		245	addition to that, when the stacks used by a handler grows larger than 16kb
		246	(adjustable with $Coro::POOL_RSS) it will also exit.
		247
		248	=cut
		249
		250	our $POOL_SIZE = 8;
		251	our $POOL_RSS = 16 * 1024;
		252	our @async_pool;
		253
		254	sub pool_handler {
		255	my $cb;
		256
		257	while () {
		258	eval {
		259	while () {
		260	_pool_1 $cb;
		261	&$cb;
		262	_pool_2 $cb;
		263	&schedule;
		264	}
		265	};
		266
		267	last if $@ eq "\3async_pool terminate\2\n";
		268	warn $@ if $@;
		269	}
		270	}
		271
		272	sub async_pool(&@) {
		273	# this is also inlined into the unlock_scheduler
		274	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		275
		276	$coro->{_invoke} = [@_];
		277	$coro->ready;
		278
		279	$coro
110	}	280	}
111		281
112	=item schedule	282	=item schedule
113		283
114	Calls the scheduler. Please note that the current process will not be put	284	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	285	into the ready queue, so calling this function usually means you will
116	never be called again.	286	never be called again unless something else (e.g. an event handler) calls
		287	ready.
117		288
118	=cut	289	The canonical way to wait on external events is this:
119		290
120	my $prev;	291	{
		292	# remember current coroutine
		293	my $current = $Coro::current;
121		294
122	sub schedule {	295	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	296	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	297	# 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;	298	$current->ready;
136	&schedule;	299	undef $current;
137	}	300	};
138		301
		302	# call schedule until event occurred.
		303	# in case we are woken up for other reasons
		304	# (current still defined), loop.
		305	Coro::schedule while $current;
		306	}
		307
		308	=item cede
		309
		310	"Cede" to other coroutines. This function puts the current coroutine into the
		311	ready queue and calls C<schedule>, which has the effect of giving up the
		312	current "timeslice" to other coroutines of the same or higher priority.
		313
		314	=item Coro::cede_notself
		315
		316	Works like cede, but is not exported by default and will cede to any
		317	coroutine, regardless of priority, once.
		318
139	=item terminate	319	=item terminate [arg...]
140		320
141	Terminates the current process.	321	Terminates the current coroutine with the given status values (see L<cancel>).
		322
		323	=item killall
		324
		325	Kills/terminates/cancels all coroutines except the currently running
		326	one. This is useful after a fork, either in the child or the parent, as
		327	usually only one of them should inherit the running coroutines.
142		328
143	=cut	329	=cut
144		330
145	sub terminate {	331	sub terminate {
146	&schedule;	332	$current->cancel (@_);
		333	}
		334
		335	sub killall {
		336	for (Coro::State::list) {
		337	$_->cancel
		338	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		339	}
147	}	340	}
148		341
149	=back	342	=back
150		343
151	# dynamic methods	344	# dynamic methods
152		345
153	=head2 PROCESS METHODS	346	=head2 COROUTINE METHODS
154		347
155	These are the methods you can call on process objects.	348	These are the methods you can call on coroutine objects.
156		349
157	=over 4	350	=over 4
158		351
159	=item new Coro \⊂	352	=item new Coro \&sub [, @args...]
160		353
161	Create a new process and return it. When the sub returns the process	354	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	355	automatically terminates as if C<terminate> with the returned values were
		356	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	357	by calling the ready method.
164		358
		359	See C<async> and C<Coro::State::new> for additional info about the
		360	coroutine environment.
		361
165	=cut	362	=cut
		363
		364	sub _run_coro {
		365	terminate &{+shift};
		366	}
166		367
167	sub new {	368	sub new {
168	my $class = shift;	369	my $class = shift;
		370
		371	$class->SUPER::new (\&_run_coro, @_)
		372	}
		373
		374	=item $success = $coroutine->ready
		375
		376	Put the given coroutine into the ready queue (according to it's priority)
		377	and return true. If the coroutine is already in the ready queue, do nothing
		378	and return false.
		379
		380	=item $is_ready = $coroutine->is_ready
		381
		382	Return wether the coroutine is currently the ready queue or not,
		383
		384	=item $coroutine->cancel (arg...)
		385
		386	Terminates the given coroutine and makes it return the given arguments as
		387	status (default: the empty list). Never returns if the coroutine is the
		388	current coroutine.
		389
		390	=cut
		391
		392	sub cancel {
		393	my $self = shift;
		394	$self->{_status} = [@_];
		395
		396	if ($current == $self) {
		397	push @destroy, $self;
		398	$manager->ready;
		399	&schedule while 1;
		400	} else {
		401	$self->_cancel;
		402	}
		403	}
		404
		405	=item $coroutine->join
		406
		407	Wait until the coroutine terminates and return any values given to the
		408	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		409	from multiple coroutines.
		410
		411	=cut
		412
		413	sub join {
		414	my $self = shift;
		415
		416	unless ($self->{_status}) {
		417	my $current = $current;
		418
		419	push @{$self->{_on_destroy}}, sub {
		420	$current->ready;
		421	undef $current;
		422	};
		423
		424	&schedule while $current;
		425	}
		426
		427	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		428	}
		429
		430	=item $coroutine->on_destroy (\&cb)
		431
		432	Registers a callback that is called when this coroutine gets destroyed,
		433	but before it is joined. The callback gets passed the terminate arguments,
		434	if any.
		435
		436	=cut
		437
		438	sub on_destroy {
		439	my ($self, $cb) = @_;
		440
		441	push @{ $self->{_on_destroy} }, $cb;
		442	}
		443
		444	=item $oldprio = $coroutine->prio ($newprio)
		445
		446	Sets (or gets, if the argument is missing) the priority of the
		447	coroutine. Higher priority coroutines get run before lower priority
		448	coroutines. Priorities are small signed integers (currently -4 .. +3),
		449	that you can refer to using PRIO_xxx constants (use the import tag :prio
		450	to get then):
		451
		452	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		453	3 > 1 > 0 > -1 > -3 > -4
		454
		455	# set priority to HIGH
		456	current->prio(PRIO_HIGH);
		457
		458	The idle coroutine ($Coro::idle) always has a lower priority than any
		459	existing coroutine.
		460
		461	Changing the priority of the current coroutine will take effect immediately,
		462	but changing the priority of coroutines in the ready queue (but not
		463	running) will only take effect after the next schedule (of that
		464	coroutine). This is a bug that will be fixed in some future version.
		465
		466	=item $newprio = $coroutine->nice ($change)
		467
		468	Similar to C<prio>, but subtract the given value from the priority (i.e.
		469	higher values mean lower priority, just as in unix).
		470
		471	=item $olddesc = $coroutine->desc ($newdesc)
		472
		473	Sets (or gets in case the argument is missing) the description for this
		474	coroutine. This is just a free-form string you can associate with a coroutine.
		475
		476	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		477	can modify this member directly if you wish.
		478
		479	=item $coroutine->throw ([$scalar])
		480
		481	If C<$throw> is specified and defined, it will be thrown as an exception
		482	inside the coroutine at the next convinient point in time (usually after
		483	it gains control at the next schedule/transfer/cede). Otherwise clears the
		484	exception object.
		485
		486	The exception object will be thrown "as is" with the specified scalar in
		487	C<$@>, i.e. if it is a string, no line number or newline will be appended
		488	(unlike with C<die>).
		489
		490	This can be used as a softer means than C<cancel> to ask a coroutine to
		491	end itself, although there is no guarentee that the exception will lead to
		492	termination, and if the exception isn't caught it might well end the whole
		493	program.
		494
		495	=cut
		496
		497	sub desc {
169	my $proc = $_[0];	498	my $old = $_[0]{desc};
170	bless {	499	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	500	$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	}	501	}
184		502
185	=back	503	=back
186		504
		505	=head2 GLOBAL FUNCTIONS
		506
		507	=over 4
		508
		509	=item Coro::nready
		510
		511	Returns the number of coroutines that are currently in the ready state,
		512	i.e. that can be switched to. The value C<0> means that the only runnable
		513	coroutine is the currently running one, so C<cede> would have no effect,
		514	and C<schedule> would cause a deadlock unless there is an idle handler
		515	that wakes up some coroutines.
		516
		517	=item my $guard = Coro::guard { ... }
		518
		519	This creates and returns a guard object. Nothing happens until the object
		520	gets destroyed, in which case the codeblock given as argument will be
		521	executed. This is useful to free locks or other resources in case of a
		522	runtime error or when the coroutine gets canceled, as in both cases the
		523	guard block will be executed. The guard object supports only one method,
		524	C<< ->cancel >>, which will keep the codeblock from being executed.
		525
		526	Example: set some flag and clear it again when the coroutine gets canceled
		527	or the function returns:
		528
		529	sub do_something {
		530	my $guard = Coro::guard { $busy = 0 };
		531	$busy = 1;
		532
		533	# do something that requires $busy to be true
		534	}
		535
		536	=cut
		537
		538	sub guard(&) {
		539	bless \(my $cb = $_[0]), "Coro::guard"
		540	}
		541
		542	sub Coro::guard::cancel {
		543	${$_[0]} = sub { };
		544	}
		545
		546	sub Coro::guard::DESTROY {
		547	${$_[0]}->();
		548	}
		549
		550
		551	=item unblock_sub { ... }
		552
		553	This utility function takes a BLOCK or code reference and "unblocks" it,
		554	returning the new coderef. This means that the new coderef will return
		555	immediately without blocking, returning nothing, while the original code
		556	ref will be called (with parameters) from within its own coroutine.
		557
		558	The reason this function exists is that many event libraries (such as the
		559	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		560	of thread-safety). This means you must not block within event callbacks,
		561	otherwise you might suffer from crashes or worse.
		562
		563	This function allows your callbacks to block by executing them in another
		564	coroutine where it is safe to block. One example where blocking is handy
		565	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		566	disk.
		567
		568	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		569	creating event callbacks that want to block.
		570
		571	=cut
		572
		573	our @unblock_queue;
		574
		575	# we create a special coro because we want to cede,
		576	# to reduce pressure on the coro pool (because most callbacks
		577	# return immediately and can be reused) and because we cannot cede
		578	# inside an event callback.
		579	our $unblock_scheduler = new Coro sub {
		580	while () {
		581	while (my $cb = pop @unblock_queue) {
		582	# this is an inlined copy of async_pool
		583	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		584
		585	$coro->{_invoke} = $cb;
		586	$coro->ready;
		587	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		588	}
		589	schedule; # sleep well
		590	}
		591	};
		592	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		593
		594	sub unblock_sub(&) {
		595	my $cb = shift;
		596
		597	sub {
		598	unshift @unblock_queue, [$cb, @_];
		599	$unblock_scheduler->ready;
		600	}
		601	}
		602
		603	=back
		604
187	=cut	605	=cut
188		606
189	1;	607	1;
190		608
		609	=head1 BUGS/LIMITATIONS
		610
		611	- you must make very sure that no coro is still active on global
		612	destruction. very bad things might happen otherwise (usually segfaults).
		613
		614	- this module is not thread-safe. You should only ever use this module
		615	from the same thread (this requirement might be loosened in the future
		616	to allow per-thread schedulers, but Coro::State does not yet allow
		617	this).
		618
		619	=head1 SEE ALSO
		620
		621	Lower level Configuration, Coroutine Environment: L<Coro::State>.
		622
		623	Debugging: L<Coro::Debug>.
		624
		625	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
		626
		627	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		628
		629	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
		630
		631	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
		632
		633	Embedding: L<Coro::MakeMaker>.
		634
191	=head1 AUTHOR	635	=head1 AUTHOR
192		636
193	Marc Lehmann <pcg@goof.com>	637	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	638	http://home.schmorp.de/
195		639
196	=cut	640	=cut
197		641

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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 1.165 by root, Thu Dec 20 07:29:14 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 1.165 by root, Thu Dec 20 07:29:14 2007 UTC