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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.12 by root, Sun Jul 15 15:58:16 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
31	$VERSION = 0.05;	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 $VERSION = '3.3';
34	@EXPORT_OK = qw($current);	56
		57	our @EXPORT = qw(async 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<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
75		115
76	=cut	116	=cut
77		117
78	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
79	if ($current) {
80	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
81	}	120	if $current;
82		121
83	our $current = $main;	122	_set_current $main;
		123
		124	sub current() { $current }
84		125
85	=item $idle	126	=item $idle
86		127
87	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
88	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
89		131
90	=cut	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.
91		135
92	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
93	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
94	print STDERR "FATAL: deadlock detected\n";	138
95	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
96	};	144	};
97		145
98	# we really need priorities...	146	# this coroutine is necessary because a coroutine
99	my @ready = (); # the ready queue. hehe, rather broken ;)	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;
		158
		159	$coro->{status} \|\|= [];
		160
		161	$_->ready for @{(delete $coro->{join} ) \|\| []};
		162	$_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) \|\| []};
		163
		164	# the next line destroys the coro state, but keeps the
		165	# coroutine itself intact (we basically make it a zombie
		166	# coroutine that always runs the manager thread, so it's possible
		167	# to transfer() to this coroutine).
		168	$coro->_clone_state_from ($manager);
		169	}
		170	&schedule;
		171	}
		172	};
100		173
101	# static methods. not really.	174	# static methods. not really.
102		175
		176	=back
		177
103	=head2 STATIC METHODS	178	=head2 STATIC METHODS
104		179
105	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.
106		181
107	=over 4	182	=over 4
108		183
109	=item async { ... };	184	=item async { ... } [@args...]
110		185
111	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
112	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
113	terminated.	188	terminated.
114		189
115	=cut	190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
116		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
117	sub async(&) {	202	sub async(&@) {
118	my $pid = new Coro $_[0];	203	my $pid = new Coro @_;
119	$pid->ready;	204	$pid->ready;
120	$pid;	205	$pid
121	}	206	}
122		207
123	=item schedule	208	=item schedule
124		209
125	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
126	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
127	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
128		214
129	=cut	215	The canonical way to wait on external events is this:
130		216
131	my $prev;	217	{
		218	# remember current coroutine
		219	my $current = $Coro::current;
132		220
133	sub schedule {	221	# register a hypothetical event handler
134	local @_;	222	on_event_invoke sub {
135	# should be done using priorities :(	223	# wake up sleeping coroutine
136	($prev, $current) = ($current, shift @ready \|\| $idle);
137	Coro::State::transfer($prev, $current);
138	}
139
140	=item yield
141
142	Yield to other processes. This function puts the current process into the
143	ready queue and calls C<schedule>.
144
145	=cut
146
147	sub yield {
148	$current->ready;	224	$current->ready;
149	&schedule;	225	undef $current;
150	}	226	};
151		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
152	=item terminate	240	=item terminate [arg...]
153		241
154	Terminates the current process.	242	Terminates the current coroutine with the given status values (see L<cancel>).
155		243
156	=cut	244	=cut
157		245
158	sub terminate {	246	sub terminate {
159	&schedule;	247	$current->cancel (@_);
160	}	248	}
161		249
162	=back	250	=back
163		251
164	# dynamic methods	252	# dynamic methods
165		253
166	=head2 PROCESS METHODS	254	=head2 COROUTINE METHODS
167		255
168	These are the methods you can call on process objects.	256	These are the methods you can call on coroutine objects.
169		257
170	=over 4	258	=over 4
171		259
172	=item new Coro \⊂	260	=item new Coro \&sub [, @args...]
173		261
174	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
175	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
176	the ready queue by calling the ready method.	265	by calling the ready method.
177		266
		267	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		268
178	=cut	269	=cut
		270
		271	sub _run_coro {
		272	terminate &{+shift};
		273	}
179		274
180	sub new {	275	sub new {
181	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 {
182	my $proc = $_[0];	372	my $old = $_[0]{desc};
183	bless {	373	$_[0]{desc} = $_[1] if @_ > 1;
184	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	374	$old;
185	}, $class;
186	}
187
188	=item $process->ready
189
190	Put the current process into the ready queue.
191
192	=cut
193
194	sub ready {
195	push @ready, $_[0];
196	}	375	}
197		376
198	=back	377	=back
199		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
200	=cut	452	=cut
201		453
202	1;	454	1;
203		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
204	=head1 SEE ALSO	466	=head1 SEE ALSO
205		467
206	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	468	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
207	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	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>
208		475
209	=head1 AUTHOR	476	=head1 AUTHOR
210		477
211	Marc Lehmann <pcg@goof.com>	478	Marc Lehmann <schmorp@schmorp.de>
212	http://www.goof.com/pcg/marc/	479	http://home.schmorp.de/
213		480
214	=cut	481	=cut
215		482

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.12 by root, Sun Jul 15 15:58:16 2001 UTC vs. Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.12 by root, Sun Jul 15 15:58:16 2001 UTC vs.
Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC