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

Comparing Coro/Coro.pm (file contents):
Revision 1.35 by root, Mon Sep 24 00:16:30 2001 UTC vs.
Revision 1.105 by root, Fri Jan 5 16:55:01 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	cede;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
23	This module collection manages coroutines. Coroutines are similar to	23	This module collection manages coroutines. Coroutines are similar
24	Threads but don't run in parallel.	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.
25		30
26	This module is still experimental, see the BUGS section below.	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).
27		34
28	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
29	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30	callchain, it's own set of lexicals and it's own set of perl's most	37	its own set of lexicals and its own set of perls most important global
31	important global variables.	38	variables.
32		39
33	=cut	40	=cut
34		41
35	package Coro;	42	package Coro;
36		43
		44	use strict;
		45	no warnings "uninitialized";
		46
37	use Coro::State;	47	use Coro::State;
38		48
39	use base Exporter;	49	use base qw(Coro::State Exporter);
40		50
41	$VERSION = 0.5;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
42		54
		55	our $VERSION = '3.3';
		56
43	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
44	%EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
45	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
46	);	60	);
47	@EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
48		62
49	{	63	{
50	my @async;	64	my @async;
51	my $init;	65	my $init;
52		66
53	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
54	sub import {	68	sub import {
		69	no strict 'refs';
		70
55	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
56	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
57	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
58	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
59	my @attrs;	76	my @attrs;
60	for (@_) {	77	for (@_) {
…		…
75	};	92	};
76	}	93	}
77		94
78	}	95	}
79		96
		97	=over 4
		98
80	=item $main	99	=item $main
81		100
82	This coroutine represents the main program.	101	This coroutine represents the main program.
83		102
84	=cut	103	=cut
85		104
86	our $main = new Coro;	105	$main = new Coro;
87		106
88	=item $current (or as function: current)	107	=item $current (or as function: current)
89		108
90	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
91		115
92	=cut	116	=cut
93		117
94	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
95	if ($current) {
96	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
97	}	120	if $current;
98		121
99	our $current = $main;	122	_set_current $main;
100		123
101	sub current() { $current }	124	sub current() { $current }
102		125
103	=item $idle	126	=item $idle
104		127
105	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
106	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.
107		131
108	=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.
109		135
110	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
111	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
112	print STDERR "FATAL: deadlock detected\n";	138
113	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
114	};	144	};
		145
		146	sub _cancel {
		147	my ($self) = @_;
		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	}
115		157
116	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
117	# cannot destroy itself.	159	# cannot destroy itself.
118	my @destroy;	160	my @destroy;
		161	my $manager;
		162
119	my $manager = new Coro sub {	163	$manager = new Coro sub {
120	while() {	164	while () {
121	delete ((pop @destroy)->{_coro_state}) while @destroy;	165	(shift @destroy)->_cancel
		166	while @destroy;
		167
122	&schedule;	168	&schedule;
123	}	169	}
124	};	170	};
125		171
		172	$manager->prio (PRIO_MAX);
		173
126	# static methods. not really.	174	# static methods. not really.
127		175
		176	=back
		177
128	=head2 STATIC METHODS	178	=head2 STATIC METHODS
129		179
130	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.
131		181
132	=over 4	182	=over 4
133		183
134	=item async { ... } [@args...]	184	=item async { ... } [@args...]
135		185
136	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
137	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
138	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
139		194
140	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
141	async {	196	async {
142	print "@_\n";	197	print "@_\n";
143	} 1,2,3,4;	198	} 1,2,3,4;
144		199
145	The coderef you submit MUST NOT be a closure that refers to variables
146	in an outer scope. This does NOT work. Pass arguments into it instead.
147
148	=cut	200	=cut
149		201
150	sub async(&@) {	202	sub async(&@) {
151	my $pid = new Coro @_;	203	my $coro = new Coro @_;
152	$manager->ready; # this ensures that the stack is cloned from the manager
153	$pid->ready;	204	$coro->ready;
154	$pid;	205	$coro
		206	}
		207
		208	=item async_pool { ... } [@args...]
		209
		210	Similar to C<async>, but uses a coroutine pool, so you should not call
		211	terminate or join (although you are allowed to), and you get a coroutine
		212	that might have executed other code already (which can be good or bad :).
		213
		214	Also, the block is executed in an C<eval> context and a warning will be
		215	issued in case of an exception instead of terminating the program, as C<async> does.
		216
		217	The priority will be reset to C<0> after each job, otherwise the coroutine
		218	will be re-used "as-is".
		219
		220	The pool size is limited to 8 idle coroutines (this can be adjusted by
		221	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		222	required.
		223
		224	If you are concerned about pooled coroutines growing a lot because a
		225	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		226	terminate }> once per second or so to slowly replenish the pool.
		227
		228	=cut
		229
		230	our $POOL_SIZE = 8;
		231	our @pool;
		232
		233	sub pool_handler {
		234	while () {
		235	my ($cb, @arg) = @{ delete $current->{_invoke} };
		236
		237	eval {
		238	$cb->(@arg);
		239	};
		240	warn $@ if $@;
		241
		242	last if @pool >= $POOL_SIZE;
		243	push @pool, $current;
		244
		245	$current->prio (0);
		246	schedule;
		247	}
		248	}
		249
		250	sub async_pool(&@) {
		251	# this is also inlined into the unlock_scheduler
		252	my $coro = (pop @pool or new Coro \&pool_handler);
		253
		254	$coro->{_invoke} = [@_];
		255	$coro->ready;
		256
		257	$coro
155	}	258	}
156		259
157	=item schedule	260	=item schedule
158		261
159	Calls the scheduler. Please note that the current process will not be put	262	Calls the scheduler. Please note that the current coroutine will not be put
160	into the ready queue, so calling this function usually means you will	263	into the ready queue, so calling this function usually means you will
161	never be called again.	264	never be called again unless something else (e.g. an event handler) calls
		265	ready.
162		266
163	=cut	267	The canonical way to wait on external events is this:
		268
		269	{
		270	# remember current coroutine
		271	my $current = $Coro::current;
		272
		273	# register a hypothetical event handler
		274	on_event_invoke sub {
		275	# wake up sleeping coroutine
		276	$current->ready;
		277	undef $current;
		278	};
		279
		280	# call schedule until event occured.
		281	# in case we are woken up for other reasons
		282	# (current still defined), loop.
		283	Coro::schedule while $current;
		284	}
164		285
165	=item cede	286	=item cede
166		287
167	"Cede" to other processes. This function puts the current process into the	288	"Cede" to other coroutines. This function puts the current coroutine into the
168	ready queue and calls C<schedule>, which has the effect of giving up the	289	ready queue and calls C<schedule>, which has the effect of giving up the
169	current "timeslice" to other coroutines of the same or higher priority.	290	current "timeslice" to other coroutines of the same or higher priority.
170		291
171	=cut	292	=item Coro::cede_notself
172		293
		294	Works like cede, but is not exported by default and will cede to any
		295	coroutine, regardless of priority, once.
		296
173	=item terminate	297	=item terminate [arg...]
174		298
175	Terminates the current process.	299	Terminates the current coroutine with the given status values (see L<cancel>).
176
177	Future versions of this function will allow result arguments.
178		300
179	=cut	301	=cut
180		302
181	sub terminate {	303	sub terminate {
182	$current->cancel;	304	$current->cancel (@_);
183	&schedule;
184	die; # NORETURN
185	}	305	}
186		306
187	=back	307	=back
188		308
189	# dynamic methods	309	# dynamic methods
190		310
191	=head2 PROCESS METHODS	311	=head2 COROUTINE METHODS
192		312
193	These are the methods you can call on process objects.	313	These are the methods you can call on coroutine objects.
194		314
195	=over 4	315	=over 4
196		316
197	=item new Coro \&sub [, @args...]	317	=item new Coro \&sub [, @args...]
198		318
199	Create a new process and return it. When the sub returns the process	319	Create a new coroutine and return it. When the sub returns the coroutine
200	automatically terminates. To start the process you must first put it into	320	automatically terminates as if C<terminate> with the returned values were
		321	called. To make the coroutine run you must first put it into the ready queue
201	the ready queue by calling the ready method.	322	by calling the ready method.
202		323
203	The coderef you submit MUST NOT be a closure that refers to variables	324	Calling C<exit> in a coroutine will not work correctly, so do not do that.
204	in an outer scope. This does NOT work. Pass arguments into it instead.
205		325
206	=cut	326	=cut
207		327
208	sub _newcoro {	328	sub _run_coro {
209	terminate &{+shift};	329	terminate &{+shift};
210	}	330	}
211		331
212	sub new {	332	sub new {
213	my $class = shift;	333	my $class = shift;
214	bless {
215	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
216	}, $class;
217	}
218		334
219	=item $process->ready	335	$class->SUPER::new (\&_run_coro, @_)
		336	}
220		337
221	Put the current process into the ready queue.	338	=item $success = $coroutine->ready
222		339
223	=cut	340	Put the given coroutine into the ready queue (according to it's priority)
		341	and return true. If the coroutine is already in the ready queue, do nothing
		342	and return false.
224		343
225	=item $process->cancel	344	=item $is_ready = $coroutine->is_ready
226		345
227	Like C<terminate>, but terminates the specified process instead.	346	Return wether the coroutine is currently the ready queue or not,
		347
		348	=item $coroutine->cancel (arg...)
		349
		350	Terminates the given coroutine and makes it return the given arguments as
		351	status (default: the empty list). Never returns if the coroutine is the
		352	current coroutine.
228		353
229	=cut	354	=cut
230		355
231	sub cancel {	356	sub cancel {
		357	my $self = shift;
		358	$self->{status} = [@_];
		359
		360	if ($current == $self) {
232	push @destroy, $_[0];	361	push @destroy, $self;
233	$manager->ready;	362	$manager->ready;
234	&schedule if $current == $_[0];	363	&schedule while 1;
		364	} else {
		365	$self->_cancel;
		366	}
235	}	367	}
236		368
		369	=item $coroutine->join
		370
		371	Wait until the coroutine terminates and return any values given to the
		372	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		373	from multiple coroutine.
		374
		375	=cut
		376
		377	sub join {
		378	my $self = shift;
		379
		380	unless ($self->{status}) {
		381	my $current = $current;
		382
		383	push @{$self->{destroy_cb}}, sub {
		384	$current->ready;
		385	undef $current;
		386	};
		387
		388	&schedule while $current;
		389	}
		390
		391	wantarray ? @{$self->{status}} : $self->{status}[0];
		392	}
		393
		394	=item $coroutine->on_destroy (\&cb)
		395
		396	Registers a callback that is called when this coroutine gets destroyed,
		397	but before it is joined. The callback gets passed the terminate arguments,
		398	if any.
		399
		400	=cut
		401
		402	sub on_destroy {
		403	my ($self, $cb) = @_;
		404
		405	push @{ $self->{destroy_cb} }, $cb;
		406	}
		407
237	=item $oldprio = $process->prio($newprio)	408	=item $oldprio = $coroutine->prio ($newprio)
238		409
239	Sets the priority of the process. Higher priority processes get run before	410	Sets (or gets, if the argument is missing) the priority of the
240	lower priority processes. Priorities are smalled signed integer (currently	411	coroutine. Higher priority coroutines get run before lower priority
		412	coroutines. Priorities are small signed integers (currently -4 .. +3),
241	-4 .. +3), that you can refer to using PRIO_xxx constants (use the import	413	that you can refer to using PRIO_xxx constants (use the import tag :prio
242	tag :prio to get then):	414	to get then):
243		415
244	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	416	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
245	3 > 1 > 0 > -1 > -3 > -4	417	3 > 1 > 0 > -1 > -3 > -4
246		418
247	# set priority to HIGH	419	# set priority to HIGH
248	current->prio(PRIO_HIGH);	420	current->prio(PRIO_HIGH);
249		421
250	The idle coroutine ($Coro::idle) always has a lower priority than any	422	The idle coroutine ($Coro::idle) always has a lower priority than any
251	existing coroutine.	423	existing coroutine.
252		424
253	Changing the priority of the current process will take effect immediately,	425	Changing the priority of the current coroutine will take effect immediately,
254	but changing the priority of processes in the ready queue (but not	426	but changing the priority of coroutines in the ready queue (but not
255	running) will only take effect after the next schedule (of that	427	running) will only take effect after the next schedule (of that
256	process). This is a bug that will be fixed in some future version.	428	coroutine). This is a bug that will be fixed in some future version.
257		429
258	=cut
259
260	sub prio {
261	my $old = $_[0]{prio};
262	$_[0]{prio} = $_[1] if @_ > 1;
263	$old;
264	}
265
266	=item $newprio = $process->nice($change)	430	=item $newprio = $coroutine->nice ($change)
267		431
268	Similar to C<prio>, but subtract the given value from the priority (i.e.	432	Similar to C<prio>, but subtract the given value from the priority (i.e.
269	higher values mean lower priority, just as in unix).	433	higher values mean lower priority, just as in unix).
270		434
271	=cut	435	=item $olddesc = $coroutine->desc ($newdesc)
272		436
273	sub nice {	437	Sets (or gets in case the argument is missing) the description for this
274	$_[0]{prio} -= $_[1];	438	coroutine. This is just a free-form string you can associate with a coroutine.
		439
		440	=cut
		441
		442	sub desc {
		443	my $old = $_[0]{desc};
		444	$_[0]{desc} = $_[1] if @_ > 1;
		445	$old;
275	}	446	}
276		447
277	=back	448	=back
278		449
		450	=head2 GLOBAL FUNCTIONS
		451
		452	=over 4
		453
		454	=item Coro::nready
		455
		456	Returns the number of coroutines that are currently in the ready state,
		457	i.e. that can be swicthed to. The value C<0> means that the only runnable
		458	coroutine is the currently running one, so C<cede> would have no effect,
		459	and C<schedule> would cause a deadlock unless there is an idle handler
		460	that wakes up some coroutines.
		461
		462	=item my $guard = Coro::guard { ... }
		463
		464	This creates and returns a guard object. Nothing happens until the objetc
		465	gets destroyed, in which case the codeblock given as argument will be
		466	executed. This is useful to free locks or other resources in case of a
		467	runtime error or when the coroutine gets canceled, as in both cases the
		468	guard block will be executed. The guard object supports only one method,
		469	C<< ->cancel >>, which will keep the codeblock from being executed.
		470
		471	Example: set some flag and clear it again when the coroutine gets canceled
		472	or the function returns:
		473
		474	sub do_something {
		475	my $guard = Coro::guard { $busy = 0 };
		476	$busy = 1;
		477
		478	# do something that requires $busy to be true
		479	}
		480
		481	=cut
		482
		483	sub guard(&) {
		484	bless \(my $cb = $_[0]), "Coro::guard"
		485	}
		486
		487	sub Coro::guard::cancel {
		488	${$_[0]} = sub { };
		489	}
		490
		491	sub Coro::guard::DESTROY {
		492	${$_[0]}->();
		493	}
		494
		495
		496	=item unblock_sub { ... }
		497
		498	This utility function takes a BLOCK or code reference and "unblocks" it,
		499	returning the new coderef. This means that the new coderef will return
		500	immediately without blocking, returning nothing, while the original code
		501	ref will be called (with parameters) from within its own coroutine.
		502
		503	The reason this fucntion exists is that many event libraries (such as the
		504	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		505	of thread-safety). This means you must not block within event callbacks,
		506	otherwise you might suffer from crashes or worse.
		507
		508	This function allows your callbacks to block by executing them in another
		509	coroutine where it is safe to block. One example where blocking is handy
		510	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		511	disk.
		512
		513	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		514	creating event callbacks that want to block.
		515
		516	=cut
		517
		518	our @unblock_queue;
		519
		520	# we create a special coro because we want to cede,
		521	# to reduce pressure on the coro pool (because most callbacks
		522	# return immediately and can be reused) and because we cannot cede
		523	# inside an event callback.
		524	our $unblock_scheduler = async {
		525	while () {
		526	while (my $cb = pop @unblock_queue) {
		527	# this is an inlined copy of async_pool
		528	my $coro = (pop @pool or new Coro \&pool_handler);
		529
		530	$coro->{_invoke} = $cb;
		531	$coro->ready;
		532	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		533	}
		534	schedule; # sleep well
		535	}
		536	};
		537
		538	sub unblock_sub(&) {
		539	my $cb = shift;
		540
		541	sub {
		542	unshift @unblock_queue, [$cb, @_];
		543	$unblock_scheduler->ready;
		544	}
		545	}
		546
		547	=back
		548
279	=cut	549	=cut
280		550
281	1;	551	1;
282		552
283	=head1 BUGS/LIMITATIONS	553	=head1 BUGS/LIMITATIONS
284		554
285	- you must make very sure that no coro is still active on global destruction.	555	- you must make very sure that no coro is still active on global
286	very bad things might happen otherwise (usually segfaults).	556	destruction. very bad things might happen otherwise (usually segfaults).
		557
287	- this module is not thread-safe. You must only ever use this module from	558	- this module is not thread-safe. You should only ever use this module
288	the same thread (this requirement might be loosened in the future to	559	from the same thread (this requirement might be losened in the future
289	allow per-thread schedulers, but Coro::State does not yet allow this).	560	to allow per-thread schedulers, but Coro::State does not yet allow
		561	this).
290		562
291	=head1 SEE ALSO	563	=head1 SEE ALSO
292		564
293	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	565	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
294	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,	566
295	L<Coro::Handle>, L<Coro::Socket>.	567	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		568
		569	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		570
		571	Embedding: L<Coro:MakeMaker>
296		572
297	=head1 AUTHOR	573	=head1 AUTHOR
298		574
299	Marc Lehmann <pcg@goof.com>	575	Marc Lehmann <schmorp@schmorp.de>
300	http://www.goof.com/pcg/marc/	576	http://home.schmorp.de/
301		577
302	=cut	578	=cut
303		579

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Comparing Coro/Coro.pm (file contents): Revision 1.35 by root, Mon Sep 24 00:16:30 2001 UTC vs. Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.35 by root, Mon Sep 24 00:16:30 2001 UTC vs.
Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC