[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 1.101 by root, Fri Dec 29 08:36:34 2006 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 use din this module also
		26	guarentees 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
		51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
		54
31	$VERSION = 0.03;	55	our $VERSION = '3.3';
32		56
33	@EXPORT = qw(async yield schedule);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
34	@EXPORT_OK = qw($current);	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 essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
		115
		116	=cut
		117
		118	# maybe some other module used Coro::Specific before...
		119	$main->{specific} = $current->{specific}
		120	if $current;
		121
		122	_set_current $main;
		123
		124	sub current() { $current }
		125
		126	=item $idle
		127
		128	A callback that is called whenever the scheduler finds no ready coroutines
		129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
		131
		132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
		135
		136	Please note that if your callback recursively invokes perl (e.g. for event
		137	handlers), then it must be prepared to be called recursively.
		138
		139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
66	};	144	};
67		145
68	=item $main	146	# this coroutine is necessary because a coroutine
		147	# cannot destroy itself.
		148	my @destroy;
		149	my $manager; $manager = new Coro sub {
		150	while () {
		151	# by overwriting the state object with the manager we destroy it
		152	# while still being able to schedule this coroutine (in case it has
		153	# been readied multiple times. this is harmless since the manager
		154	# can be called as many times as neccessary and will always
		155	# remove itself from the runqueue
		156	while (@destroy) {
		157	my $coro = pop @destroy;
69		158
70	This coroutine represents the main program.	159	$coro->{status} \|\|= [];
71		160
72	=cut	161	$_->ready for @{(delete $coro->{join} ) \|\| []};
		162	$_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) \|\| []};
73		163
74	$main = new Coro;	164	# the next line destroys the coro state, but keeps the
75		165	# coroutine itself intact (we basically make it a zombie
76	=item $current	166	# coroutine that always runs the manager thread, so it's possible
77		167	# to transfer() to this coroutine).
78	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	168	$coro->_clone_state_from ($manager);
79		169	}
80	=cut	170	&schedule;
81		171	}
82	# maybe some other module used Coro::Specific before...	172	};
83	if ($current) {
84	$main->{specific} = $current->{specific};
85	}
86
87	$current = $main;
88
89	# we really need priorities...
90	my @ready = (); # the ready queue. hehe, rather broken ;)
91		173
92	# static methods. not really.	174	# static methods. not really.
93		175
		176	=back
		177
94	=head2 STATIC METHODS	178	=head2 STATIC METHODS
95		179
96	Static methods are actually functions that operate on the current process only.	180	Static methods are actually functions that operate on the current coroutine only.
97		181
98	=over 4	182	=over 4
99		183
100	=item async { ... };	184	=item async { ... } [@args...]
101		185
102	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
103	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
104	terminated.	188	terminated.
105		189
106	=cut	190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
107		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
		194
		195	# create a new coroutine that just prints its arguments
		196	async {
		197	print "@_\n";
		198	} 1,2,3,4;
		199
		200	=cut
		201
108	sub async(&) {	202	sub async(&@) {
109	(new Coro $_[0])->ready;	203	my $pid = new Coro @_;
		204	$pid->ready;
		205	$pid
110	}	206	}
111		207
112	=item schedule	208	=item schedule
113		209
114	Calls the scheduler. Please note that the current process will not be put	210	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	211	into the ready queue, so calling this function usually means you will
116	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
117		214
118	=cut	215	The canonical way to wait on external events is this:
119		216
120	my $prev;	217	{
		218	# remember current coroutine
		219	my $current = $Coro::current;
121		220
122	sub schedule {	221	# register a hypothetical event handler
123	($prev, $current) = ($current, shift @ready);	222	on_event_invoke sub {
124	Coro::State::transfer($prev, $current);	223	# 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;	224	$current->ready;
136	&schedule;	225	undef $current;
137	}	226	};
138		227
		228	# call schedule until event occured.
		229	# in case we are woken up for other reasons
		230	# (current still defined), loop.
		231	Coro::schedule while $current;
		232	}
		233
		234	=item cede
		235
		236	"Cede" to other coroutines. This function puts the current coroutine into the
		237	ready queue and calls C<schedule>, which has the effect of giving up the
		238	current "timeslice" to other coroutines of the same or higher priority.
		239
139	=item terminate	240	=item terminate [arg...]
140		241
141	Terminates the current process.	242	Terminates the current coroutine with the given status values (see L<cancel>).
142		243
143	=cut	244	=cut
144		245
145	sub terminate {	246	sub terminate {
146	&schedule;	247	$current->cancel (@_);
147	}	248	}
148		249
149	=back	250	=back
150		251
151	# dynamic methods	252	# dynamic methods
152		253
153	=head2 PROCESS METHODS	254	=head2 COROUTINE METHODS
154		255
155	These are the methods you can call on process objects.	256	These are the methods you can call on coroutine objects.
156		257
157	=over 4	258	=over 4
158		259
159	=item new Coro \⊂	260	=item new Coro \&sub [, @args...]
160		261
161	Create a new process and return it. When the sub returns the process	262	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	263	automatically terminates as if C<terminate> with the returned values were
		264	called. To make the coroutine run you must first put it into the ready queue
163	the ready queue by calling the ready method.	265	by calling the ready method.
164		266
		267	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		268
165	=cut	269	=cut
		270
		271	sub _run_coro {
		272	terminate &{+shift};
		273	}
166		274
167	sub new {	275	sub new {
168	my $class = shift;	276	my $class = shift;
		277
		278	$class->SUPER::new (\&_run_coro, @_)
		279	}
		280
		281	=item $success = $coroutine->ready
		282
		283	Put the given coroutine into the ready queue (according to it's priority)
		284	and return true. If the coroutine is already in the ready queue, do nothing
		285	and return false.
		286
		287	=item $is_ready = $coroutine->is_ready
		288
		289	Return wether the coroutine is currently the ready queue or not,
		290
		291	=item $coroutine->cancel (arg...)
		292
		293	Terminates the given coroutine and makes it return the given arguments as
		294	status (default: the empty list).
		295
		296	=cut
		297
		298	sub cancel {
		299	my $self = shift;
		300	$self->{status} = [@_];
		301	push @destroy, $self;
		302	$manager->ready;
		303	&schedule if $current == $self;
		304	}
		305
		306	=item $coroutine->join
		307
		308	Wait until the coroutine terminates and return any values given to the
		309	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		310	from multiple coroutine.
		311
		312	=cut
		313
		314	sub join {
		315	my $self = shift;
		316	unless ($self->{status}) {
		317	push @{$self->{join}}, $current;
		318	&schedule;
		319	}
		320	wantarray ? @{$self->{status}} : $self->{status}[0];
		321	}
		322
		323	=item $coroutine->on_destroy (\&cb)
		324
		325	Registers a callback that is called when this coroutine gets destroyed,
		326	but before it is joined. The callback gets passed the terminate arguments,
		327	if any.
		328
		329	=cut
		330
		331	sub on_destroy {
		332	my ($self, $cb) = @_;
		333
		334	push @{ $self->{destroy_cb} }, $cb;
		335	}
		336
		337	=item $oldprio = $coroutine->prio ($newprio)
		338
		339	Sets (or gets, if the argument is missing) the priority of the
		340	coroutine. Higher priority coroutines get run before lower priority
		341	coroutines. Priorities are small signed integers (currently -4 .. +3),
		342	that you can refer to using PRIO_xxx constants (use the import tag :prio
		343	to get then):
		344
		345	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		346	3 > 1 > 0 > -1 > -3 > -4
		347
		348	# set priority to HIGH
		349	current->prio(PRIO_HIGH);
		350
		351	The idle coroutine ($Coro::idle) always has a lower priority than any
		352	existing coroutine.
		353
		354	Changing the priority of the current coroutine will take effect immediately,
		355	but changing the priority of coroutines in the ready queue (but not
		356	running) will only take effect after the next schedule (of that
		357	coroutine). This is a bug that will be fixed in some future version.
		358
		359	=item $newprio = $coroutine->nice ($change)
		360
		361	Similar to C<prio>, but subtract the given value from the priority (i.e.
		362	higher values mean lower priority, just as in unix).
		363
		364	=item $olddesc = $coroutine->desc ($newdesc)
		365
		366	Sets (or gets in case the argument is missing) the description for this
		367	coroutine. This is just a free-form string you can associate with a coroutine.
		368
		369	=cut
		370
		371	sub desc {
169	my $proc = $_[0];	372	my $old = $_[0]{desc};
170	bless {	373	$_[0]{desc} = $_[1] if @_ > 1;
171	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	374	$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	}	375	}
184		376
185	=back	377	=back
186		378
		379	=head2 GLOBAL FUNCTIONS
		380
		381	=over 4
		382
		383	=item Coro::nready
		384
		385	Returns the number of coroutines that are currently in the ready state,
		386	i.e. that can be swicthed to. The value C<0> means that the only runnable
		387	coroutine is the currently running one, so C<cede> would have no effect,
		388	and C<schedule> would cause a deadlock unless there is an idle handler
		389	that wakes up some coroutines.
		390
		391	=item unblock_sub { ... }
		392
		393	This utility function takes a BLOCK or code reference and "unblocks" it,
		394	returning the new coderef. This means that the new coderef will return
		395	immediately without blocking, returning nothing, while the original code
		396	ref will be called (with parameters) from within its own coroutine.
		397
		398	The reason this fucntion exists is that many event libraries (such as the
		399	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		400	of thread-safety). This means you must not block within event callbacks,
		401	otherwise you might suffer from crashes or worse.
		402
		403	This function allows your callbacks to block by executing them in another
		404	coroutine where it is safe to block. One example where blocking is handy
		405	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		406	disk.
		407
		408	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		409	creating event callbacks that want to block.
		410
		411	=cut
		412
		413	our @unblock_pool;
		414	our @unblock_queue;
		415	our $UNBLOCK_POOL_SIZE = 2;
		416
		417	sub unblock_handler_ {
		418	while () {
		419	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		420	$cb->(@arg);
		421
		422	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		423	push @unblock_pool, $Coro::current;
		424	schedule;
		425	}
		426	}
		427
		428	our $unblock_scheduler = async {
		429	while () {
		430	while (my $cb = pop @unblock_queue) {
		431	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		432	$handler->{arg} = $cb;
		433	$handler->ready;
		434	cede;
		435	}
		436
		437	schedule;
		438	}
		439	};
		440
		441	sub unblock_sub(&) {
		442	my $cb = shift;
		443
		444	sub {
		445	push @unblock_queue, [$cb, @_];
		446	$unblock_scheduler->ready;
		447	}
		448	}
		449
		450	=back
		451
187	=cut	452	=cut
188		453
189	1;	454	1;
190		455
		456	=head1 BUGS/LIMITATIONS
		457
		458	- you must make very sure that no coro is still active on global
		459	destruction. very bad things might happen otherwise (usually segfaults).
		460
		461	- this module is not thread-safe. You should only ever use this module
		462	from the same thread (this requirement might be losened in the future
		463	to allow per-thread schedulers, but Coro::State does not yet allow
		464	this).
		465
		466	=head1 SEE ALSO
		467
		468	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
		469
		470	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		471
		472	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		473
		474	Embedding: L<Coro:MakeMaker>
		475
191	=head1 AUTHOR	476	=head1 AUTHOR
192		477
193	Marc Lehmann <pcg@goof.com>	478	Marc Lehmann <schmorp@schmorp.de>
194	http://www.goof.com/pcg/marc/	479	http://home.schmorp.de/
195		480
196	=cut	481	=cut
197		482

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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 1.101 by root, Fri Dec 29 08:36:34 2006 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.8 by root, Sat Jul 14 22:14:21 2001 UTC vs.
Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC