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

Comparing Coro/Coro.pm (file contents):
Revision 1.13 by root, Tue Jul 17 00:24:14 2001 UTC vs.
Revision 1.125 by root, Fri Apr 27 19:35:58 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 = 0.05;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
32		54
33	@EXPORT = qw(async yield schedule terminate);	55	our $VERSION = '3.62';
34	@EXPORT_OK = qw($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	}
		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<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essential you are encouraged to use the
		114	C<Coro::current> function instead.
75		115
76	=cut	116	=cut
77		117
78	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
79	if ($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	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
96	};	144	};
97		145
98	# we really need priorities...	146	sub _cancel {
99	## my @ready; #d#	147	my ($self) = @_;
100	our @ready = (); # the ready queue. hehe, rather broken ;)	148
		149	# free coroutine data and mark as destructed
		150	$self->_destroy
		151	or return;
		152
		153	# call all destruction callbacks
		154	$_->(@{$self->{status}})
		155	for @{(delete $self->{destroy_cb}) \|\| []};
		156	}
		157
		158	# this coroutine is necessary because a coroutine
		159	# cannot destroy itself.
		160	my @destroy;
		161	my $manager;
		162
		163	$manager = new Coro sub {
		164	while () {
		165	(shift @destroy)->_cancel
		166	while @destroy;
		167
		168	&schedule;
		169	}
		170	};
		171
		172	$manager->prio (PRIO_MAX);
101		173
102	# static methods. not really.	174	# static methods. not really.
103		175
		176	=back
		177
104	=head2 STATIC METHODS	178	=head2 STATIC METHODS
105		179
106	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.
107		181
108	=over 4	182	=over 4
109		183
110	=item async { ... } [@args...]	184	=item async { ... } [@args...]
111		185
112	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
113	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
114	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will do the same as calling exit outside
		191	the coroutine. Likewise, when the coroutine dies, the program will exit,
		192	just as it would in the main program.
115		193
116	# create a new coroutine that just prints its arguments	194	# create a new coroutine that just prints its arguments
117	async {	195	async {
118	print "@_\n";	196	print "@_\n";
119	} 1,2,3,4;	197	} 1,2,3,4;
120		198
121	The coderef you submit MUST NOT be a closure that refers to variables
122	in an outer scope. This does NOT work. Pass arguments into it instead.
123
124	=cut	199	=cut
125		200
126	sub async(&@) {	201	sub async(&@) {
127	my $pid = new Coro @_;	202	my $coro = new Coro @_;
128	$pid->ready;	203	$coro->ready;
129	$pid;	204	$coro
		205	}
		206
		207	=item async_pool { ... } [@args...]
		208
		209	Similar to C<async>, but uses a coroutine pool, so you should not call
		210	terminate or join (although you are allowed to), and you get a coroutine
		211	that might have executed other code already (which can be good or bad :).
		212
		213	Also, the block is executed in an C<eval> context and a warning will be
		214	issued in case of an exception instead of terminating the program, as
		215	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		216	will not work in the expected way, unless you call terminate or cancel,
		217	which somehow defeats the purpose of pooling.
		218
		219	The priority will be reset to C<0> after each job, otherwise the coroutine
		220	will be re-used "as-is".
		221
		222	The pool size is limited to 8 idle coroutines (this can be adjusted by
		223	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		224	required.
		225
		226	If you are concerned about pooled coroutines growing a lot because a
		227	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		228	terminate }> once per second or so to slowly replenish the pool.
		229
		230	=cut
		231
		232	our $POOL_SIZE = 8;
		233	our @pool;
		234
		235	sub pool_handler {
		236	while () {
		237	eval {
		238	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		239	$cb->(@arg);
		240	};
		241	warn $@ if $@;
		242
		243	last if @pool >= $POOL_SIZE;
		244	push @pool, $current;
		245
		246	$current->save (Coro::State::SAVE_DEF);
		247	$current->prio (0);
		248	schedule;
		249	}
		250	}
		251
		252	sub async_pool(&@) {
		253	# this is also inlined into the unlock_scheduler
		254	my $coro = (pop @pool or new Coro \&pool_handler);
		255
		256	$coro->{_invoke} = [@_];
		257	$coro->ready;
		258
		259	$coro
130	}	260	}
131		261
132	=item schedule	262	=item schedule
133		263
134	Calls the scheduler. Please note that the current process will not be put	264	Calls the scheduler. Please note that the current coroutine will not be put
135	into the ready queue, so calling this function usually means you will	265	into the ready queue, so calling this function usually means you will
136	never be called again.	266	never be called again unless something else (e.g. an event handler) calls
		267	ready.
137		268
138	=cut	269	The canonical way to wait on external events is this:
139		270
140	my $prev;	271	{
		272	# remember current coroutine
		273	my $current = $Coro::current;
141		274
142	sub schedule {	275	# register a hypothetical event handler
143	# should be done using priorities :(	276	on_event_invoke sub {
144	($prev, $current) = ($current, shift @ready \|\| $idle);	277	# wake up sleeping coroutine
145	Coro::State::transfer($prev, $current);
146	}
147
148	=item yield
149
150	Yield to other processes. This function puts the current process into the
151	ready queue and calls C<schedule>.
152
153	=cut
154
155	sub yield {
156	$current->ready;	278	$current->ready;
157	&schedule;	279	undef $current;
158	}	280	};
159		281
		282	# call schedule until event occurred.
		283	# in case we are woken up for other reasons
		284	# (current still defined), loop.
		285	Coro::schedule while $current;
		286	}
		287
		288	=item cede
		289
		290	"Cede" to other coroutines. This function puts the current coroutine into the
		291	ready queue and calls C<schedule>, which has the effect of giving up the
		292	current "timeslice" to other coroutines of the same or higher priority.
		293
		294	Returns true if at least one coroutine switch has happened.
		295
		296	=item Coro::cede_notself
		297
		298	Works like cede, but is not exported by default and will cede to any
		299	coroutine, regardless of priority, once.
		300
		301	Returns true if at least one coroutine switch has happened.
		302
160	=item terminate	303	=item terminate [arg...]
161		304
162	Terminates the current process.	305	Terminates the current coroutine with the given status values (see L<cancel>).
163
164	Future versions of this function will allow result arguments.
165		306
166	=cut	307	=cut
167		308
168	sub terminate {	309	sub terminate {
169	$current->{_results} = [@_];	310	$current->cancel (@_);
170	&schedule;
171	}	311	}
172		312
173	=back	313	=back
174		314
175	# dynamic methods	315	# dynamic methods
176		316
177	=head2 PROCESS METHODS	317	=head2 COROUTINE METHODS
178		318
179	These are the methods you can call on process objects.	319	These are the methods you can call on coroutine objects.
180		320
181	=over 4	321	=over 4
182		322
183	=item new Coro \&sub [, @args...]	323	=item new Coro \&sub [, @args...]
184		324
185	Create a new process and return it. When the sub returns the process	325	Create a new coroutine and return it. When the sub returns the coroutine
186	automatically terminates. To start the process you must first put it into	326	automatically terminates as if C<terminate> with the returned values were
		327	called. To make the coroutine run you must first put it into the ready queue
187	the ready queue by calling the ready method.	328	by calling the ready method.
188		329
189	The coderef you submit MUST NOT be a closure that refers to variables	330	See C<async> for additional discussion.
190	in an outer scope. This does NOT work. Pass arguments into it instead.
191		331
192	=cut	332	=cut
193		333
194	sub _newcoro {	334	sub _run_coro {
195	terminate &{+shift};	335	terminate &{+shift};
196	}	336	}
197		337
198	sub new {	338	sub new {
199	my $class = shift;	339	my $class = shift;
200	bless {
201	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
202	}, $class;
203	}
204		340
205	=item $process->ready	341	$class->SUPER::new (\&_run_coro, @_)
		342	}
206		343
207	Put the current process into the ready queue.	344	=item $success = $coroutine->ready
208		345
209	=cut	346	Put the given coroutine into the ready queue (according to it's priority)
		347	and return true. If the coroutine is already in the ready queue, do nothing
		348	and return false.
210		349
211	sub ready {	350	=item $is_ready = $coroutine->is_ready
212	push @ready, $_[0];	351
		352	Return wether the coroutine is currently the ready queue or not,
		353
		354	=item $coroutine->cancel (arg...)
		355
		356	Terminates the given coroutine and makes it return the given arguments as
		357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
		359
		360	=cut
		361
		362	sub cancel {
		363	my $self = shift;
		364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
		367	push @destroy, $self;
		368	$manager->ready;
		369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
		373	}
		374
		375	=item $coroutine->join
		376
		377	Wait until the coroutine terminates and return any values given to the
		378	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		379	from multiple coroutine.
		380
		381	=cut
		382
		383	sub join {
		384	my $self = shift;
		385
		386	unless ($self->{status}) {
		387	my $current = $current;
		388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
		395	}
		396
		397	wantarray ? @{$self->{status}} : $self->{status}[0];
		398	}
		399
		400	=item $coroutine->on_destroy (\&cb)
		401
		402	Registers a callback that is called when this coroutine gets destroyed,
		403	but before it is joined. The callback gets passed the terminate arguments,
		404	if any.
		405
		406	=cut
		407
		408	sub on_destroy {
		409	my ($self, $cb) = @_;
		410
		411	push @{ $self->{destroy_cb} }, $cb;
		412	}
		413
		414	=item $oldprio = $coroutine->prio ($newprio)
		415
		416	Sets (or gets, if the argument is missing) the priority of the
		417	coroutine. Higher priority coroutines get run before lower priority
		418	coroutines. Priorities are small signed integers (currently -4 .. +3),
		419	that you can refer to using PRIO_xxx constants (use the import tag :prio
		420	to get then):
		421
		422	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		423	3 > 1 > 0 > -1 > -3 > -4
		424
		425	# set priority to HIGH
		426	current->prio(PRIO_HIGH);
		427
		428	The idle coroutine ($Coro::idle) always has a lower priority than any
		429	existing coroutine.
		430
		431	Changing the priority of the current coroutine will take effect immediately,
		432	but changing the priority of coroutines in the ready queue (but not
		433	running) will only take effect after the next schedule (of that
		434	coroutine). This is a bug that will be fixed in some future version.
		435
		436	=item $newprio = $coroutine->nice ($change)
		437
		438	Similar to C<prio>, but subtract the given value from the priority (i.e.
		439	higher values mean lower priority, just as in unix).
		440
		441	=item $olddesc = $coroutine->desc ($newdesc)
		442
		443	Sets (or gets in case the argument is missing) the description for this
		444	coroutine. This is just a free-form string you can associate with a coroutine.
		445
		446	=cut
		447
		448	sub desc {
		449	my $old = $_[0]{desc};
		450	$_[0]{desc} = $_[1] if @_ > 1;
		451	$old;
213	}	452	}
214		453
215	=back	454	=back
216		455
		456	=head2 GLOBAL FUNCTIONS
		457
		458	=over 4
		459
		460	=item Coro::nready
		461
		462	Returns the number of coroutines that are currently in the ready state,
		463	i.e. that can be switched to. The value C<0> means that the only runnable
		464	coroutine is the currently running one, so C<cede> would have no effect,
		465	and C<schedule> would cause a deadlock unless there is an idle handler
		466	that wakes up some coroutines.
		467
		468	=item my $guard = Coro::guard { ... }
		469
		470	This creates and returns a guard object. Nothing happens until the object
		471	gets destroyed, in which case the codeblock given as argument will be
		472	executed. This is useful to free locks or other resources in case of a
		473	runtime error or when the coroutine gets canceled, as in both cases the
		474	guard block will be executed. The guard object supports only one method,
		475	C<< ->cancel >>, which will keep the codeblock from being executed.
		476
		477	Example: set some flag and clear it again when the coroutine gets canceled
		478	or the function returns:
		479
		480	sub do_something {
		481	my $guard = Coro::guard { $busy = 0 };
		482	$busy = 1;
		483
		484	# do something that requires $busy to be true
		485	}
		486
		487	=cut
		488
		489	sub guard(&) {
		490	bless \(my $cb = $_[0]), "Coro::guard"
		491	}
		492
		493	sub Coro::guard::cancel {
		494	${$_[0]} = sub { };
		495	}
		496
		497	sub Coro::guard::DESTROY {
		498	${$_[0]}->();
		499	}
		500
		501
		502	=item unblock_sub { ... }
		503
		504	This utility function takes a BLOCK or code reference and "unblocks" it,
		505	returning the new coderef. This means that the new coderef will return
		506	immediately without blocking, returning nothing, while the original code
		507	ref will be called (with parameters) from within its own coroutine.
		508
		509	The reason this function exists is that many event libraries (such as the
		510	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		511	of thread-safety). This means you must not block within event callbacks,
		512	otherwise you might suffer from crashes or worse.
		513
		514	This function allows your callbacks to block by executing them in another
		515	coroutine where it is safe to block. One example where blocking is handy
		516	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		517	disk.
		518
		519	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		520	creating event callbacks that want to block.
		521
		522	=cut
		523
		524	our @unblock_queue;
		525
		526	# we create a special coro because we want to cede,
		527	# to reduce pressure on the coro pool (because most callbacks
		528	# return immediately and can be reused) and because we cannot cede
		529	# inside an event callback.
		530	our $unblock_scheduler = async {
		531	while () {
		532	while (my $cb = pop @unblock_queue) {
		533	# this is an inlined copy of async_pool
		534	my $coro = (pop @pool or new Coro \&pool_handler);
		535
		536	$coro->{_invoke} = $cb;
		537	$coro->ready;
		538	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		539	}
		540	schedule; # sleep well
		541	}
		542	};
		543
		544	sub unblock_sub(&) {
		545	my $cb = shift;
		546
		547	sub {
		548	unshift @unblock_queue, [$cb, @_];
		549	$unblock_scheduler->ready;
		550	}
		551	}
		552
		553	=back
		554
217	=cut	555	=cut
218		556
219	1;	557	1;
220		558
		559	=head1 BUGS/LIMITATIONS
		560
		561	- you must make very sure that no coro is still active on global
		562	destruction. very bad things might happen otherwise (usually segfaults).
		563
		564	- this module is not thread-safe. You should only ever use this module
		565	from the same thread (this requirement might be loosened in the future
		566	to allow per-thread schedulers, but Coro::State does not yet allow
		567	this).
		568
221	=head1 SEE ALSO	569	=head1 SEE ALSO
222		570
223	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	571	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
224	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	572
		573	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		574
		575	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		576
		577	Embedding: L<Coro:MakeMaker>
225		578
226	=head1 AUTHOR	579	=head1 AUTHOR
227		580
228	Marc Lehmann <pcg@goof.com>	581	Marc Lehmann <schmorp@schmorp.de>
229	http://www.goof.com/pcg/marc/	582	http://home.schmorp.de/
230		583
231	=cut	584	=cut
232		585

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Comparing Coro/Coro.pm (file contents): Revision 1.13 by root, Tue Jul 17 00:24:14 2001 UTC vs. Revision 1.125 by root, Fri Apr 27 19:35:58 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.13 by root, Tue Jul 17 00:24:14 2001 UTC vs.
Revision 1.125 by root, Fri Apr 27 19:35:58 2007 UTC