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

Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.138 by root, Wed Sep 26 19:27:04 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 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.
25		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
26	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	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
29	important global variables.	38	variables.
30		39
31	=cut	40	=cut
32		41
33	package Coro;	42	package Coro;
34		43
…		…
41		50
42	our $idle; # idle handler	51	our $idle; # idle handler
43	our $main; # main coroutine	52	our $main; # main coroutine
44	our $current; # current coroutine	53	our $current; # current coroutine
45		54
46	our $VERSION = '3.0';	55	our $VERSION = '3.8';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53		62
54	{	63	{
55	my @async;	64	my @async;
56	my $init;	65	my $init;
57		66
58	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
59	sub import {	68	sub import {
60	no strict 'refs';	69	no strict 'refs';
61		70
62	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
63		72
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
99		108
100	The current coroutine (the last coroutine switched to). The initial value	109	The current coroutine (the last coroutine switched to). The initial value
101	is C<$main> (of course).	110	is C<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
		118	$main->{desc} = "[main::]";
		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
112	}	122	if $current;
113		123
114	$current = $main;	124	_set_current $main;
115		125
116	sub current() { $current }	126	sub current() { $current }
117		127
118	=item $idle	128	=item $idle
119		129
120	A callback that is called whenever the scheduler finds no ready coroutines	130	A callback that is called whenever the scheduler finds no ready coroutines
121	to run. The default implementation prints "FATAL: deadlock detected" and	131	to run. The default implementation prints "FATAL: deadlock detected" and
122	exits.	132	exits, because the program has no other way to continue.
123		133
124	This hook is overwritten by modules such as C<Coro::Timer> and	134	This hook is overwritten by modules such as C<Coro::Timer> and
125	C<Coro::Event> to wait on an external event that hopefully wakes up some	135	C<Coro::Event> to wait on an external event that hopefully wake up a
126	coroutine.	136	coroutine so the scheduler can run it.
		137
		138	Please note that if your callback recursively invokes perl (e.g. for event
		139	handlers), then it must be prepared to be called recursively.
127		140
128	=cut	141	=cut
129		142
130	$idle = sub {	143	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
132	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
133	};	146	};
		147
		148	sub _cancel {
		149	my ($self) = @_;
		150
		151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
		154
		155	# call all destruction callbacks
		156	$_->(@{$self->{status}})
		157	for @{(delete $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	sub _do_trace {
		161	$current->{_trace_cb}->();
		162	}
134		163
135	# this coroutine is necessary because a coroutine	164	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	165	# cannot destroy itself.
137	my @destroy;	166	my @destroy;
		167	my $manager;
		168
138	my $manager; $manager = new Coro sub {	169	$manager = new Coro sub {
139	while () {	170	while () {
140	# by overwriting the state object with the manager we destroy it	171	(shift @destroy)->_cancel
141	# while still being able to schedule this coroutine (in case it has
142	# been readied multiple times. this is harmless since the manager
143	# can be called as many times as neccessary and will always
144	# remove itself from the runqueue
145	while (@destroy) {	172	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		173
150	# the next line destroys the coro state, but keeps the
151	# process itself intact (we basically make it a zombie
152	# process that always runs the manager thread, so it's possible
153	# to transfer() to this process).
154	$coro->_clone_state_from ($manager);
155	}
156	&schedule;	174	&schedule;
157	}	175	}
158	};	176	};
		177	$manager->desc ("[coro manager]");
		178	$manager->prio (PRIO_MAX);
159		179
160	# static methods. not really.	180	# static methods. not really.
161		181
162	=back	182	=back
163		183
164	=head2 STATIC METHODS	184	=head2 STATIC METHODS
165		185
166	Static methods are actually functions that operate on the current process only.	186	Static methods are actually functions that operate on the current coroutine only.
167		187
168	=over 4	188	=over 4
169		189
170	=item async { ... } [@args...]	190	=item async { ... } [@args...]
171		191
172	Create a new asynchronous process and return it's process object	192	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	193	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	194	terminated.
175		195
176	When the coroutine dies, the program will exit, just as in the main	196	Calling C<exit> in a coroutine will do the same as calling exit outside
177	program.	197	the coroutine. Likewise, when the coroutine dies, the program will exit,
		198	just as it would in the main program.
178		199
179	# create a new coroutine that just prints its arguments	200	# create a new coroutine that just prints its arguments
180	async {	201	async {
181	print "@_\n";	202	print "@_\n";
182	} 1,2,3,4;	203	} 1,2,3,4;
183		204
184	=cut	205	=cut
185		206
186	sub async(&@) {	207	sub async(&@) {
187	my $pid = new Coro @_;	208	my $coro = new Coro @_;
188	$pid->ready;	209	$coro->ready;
189	$pid	210	$coro
		211	}
		212
		213	=item async_pool { ... } [@args...]
		214
		215	Similar to C<async>, but uses a coroutine pool, so you should not call
		216	terminate or join (although you are allowed to), and you get a coroutine
		217	that might have executed other code already (which can be good or bad :).
		218
		219	Also, the block is executed in an C<eval> context and a warning will be
		220	issued in case of an exception instead of terminating the program, as
		221	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		222	will not work in the expected way, unless you call terminate or cancel,
		223	which somehow defeats the purpose of pooling.
		224
		225	The priority will be reset to C<0> after each job, otherwise the coroutine
		226	will be re-used "as-is".
		227
		228	The pool size is limited to 8 idle coroutines (this can be adjusted by
		229	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		230	required.
		231
		232	If you are concerned about pooled coroutines growing a lot because a
		233	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		234	{ terminate }> once per second or so to slowly replenish the pool. In
		235	addition to that, when the stacks used by a handler grows larger than 16kb
		236	(adjustable with $Coro::POOL_RSS) it will also exit.
		237
		238	=cut
		239
		240	our $POOL_SIZE = 8;
		241	our $POOL_RSS = 16 * 1024;
		242	our @async_pool;
		243
		244	sub pool_handler {
		245	my $cb;
		246
		247	while () {
		248	eval {
		249	while () {
		250	_pool_1 $cb;
		251	&$cb;
		252	_pool_2 $cb;
		253	&schedule;
		254	}
		255	};
		256
		257	last if $@ eq "\3terminate\2\n";
		258	warn $@ if $@;
		259	}
		260	}
		261
		262	sub async_pool(&@) {
		263	# this is also inlined into the unlock_scheduler
		264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		265
		266	$coro->{_invoke} = [@_];
		267	$coro->ready;
		268
		269	$coro
190	}	270	}
191		271
192	=item schedule	272	=item schedule
193		273
194	Calls the scheduler. Please note that the current process will not be put	274	Calls the scheduler. Please note that the current coroutine will not be put
195	into the ready queue, so calling this function usually means you will	275	into the ready queue, so calling this function usually means you will
196	never be called again.	276	never be called again unless something else (e.g. an event handler) calls
		277	ready.
197		278
198	=cut	279	The canonical way to wait on external events is this:
		280
		281	{
		282	# remember current coroutine
		283	my $current = $Coro::current;
		284
		285	# register a hypothetical event handler
		286	on_event_invoke sub {
		287	# wake up sleeping coroutine
		288	$current->ready;
		289	undef $current;
		290	};
		291
		292	# call schedule until event occurred.
		293	# in case we are woken up for other reasons
		294	# (current still defined), loop.
		295	Coro::schedule while $current;
		296	}
199		297
200	=item cede	298	=item cede
201		299
202	"Cede" to other processes. This function puts the current process into the	300	"Cede" to other coroutines. This function puts the current coroutine into the
203	ready queue and calls C<schedule>, which has the effect of giving up the	301	ready queue and calls C<schedule>, which has the effect of giving up the
204	current "timeslice" to other coroutines of the same or higher priority.	302	current "timeslice" to other coroutines of the same or higher priority.
205		303
206	=cut	304	Returns true if at least one coroutine switch has happened.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to any
		309	coroutine, regardless of priority, once.
		310
		311	Returns true if at least one coroutine switch has happened.
207		312
208	=item terminate [arg...]	313	=item terminate [arg...]
209		314
210	Terminates the current process with the given status values (see L<cancel>).	315	Terminates the current coroutine with the given status values (see L<cancel>).
211		316
212	=cut	317	=cut
213		318
214	sub terminate {	319	sub terminate {
215	$current->cancel (@_);	320	$current->cancel (@_);
…		…
217		322
218	=back	323	=back
219		324
220	# dynamic methods	325	# dynamic methods
221		326
222	=head2 PROCESS METHODS	327	=head2 COROUTINE METHODS
223		328
224	These are the methods you can call on process objects.	329	These are the methods you can call on coroutine objects.
225		330
226	=over 4	331	=over 4
227		332
228	=item new Coro \&sub [, @args...]	333	=item new Coro \&sub [, @args...]
229		334
230	Create a new process and return it. When the sub returns the process	335	Create a new coroutine and return it. When the sub returns the coroutine
231	automatically terminates as if C<terminate> with the returned values were	336	automatically terminates as if C<terminate> with the returned values were
232	called. To make the process run you must first put it into the ready queue	337	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	338	by calling the ready method.
234		339
235	=cut	340	See C<async> for additional discussion.
236		341
		342	=cut
		343
237	sub _new_coro {	344	sub _run_coro {
238	terminate &{+shift};	345	terminate &{+shift};
239	}	346	}
240		347
241	sub new {	348	sub new {
242	my $class = shift;	349	my $class = shift;
243		350
244	$class->SUPER::new (\&_new_coro, @_)	351	$class->SUPER::new (\&_run_coro, @_)
245	}	352	}
246		353
247	=item $process->ready	354	=item $success = $coroutine->ready
248		355
249	Put the given process into the ready queue.	356	Put the given coroutine into the ready queue (according to it's priority)
		357	and return true. If the coroutine is already in the ready queue, do nothing
		358	and return false.
250		359
251	=cut	360	=item $is_ready = $coroutine->is_ready
252		361
		362	Return wether the coroutine is currently the ready queue or not,
		363
253	=item $process->cancel (arg...)	364	=item $coroutine->cancel (arg...)
254		365
255	Terminates the given process and makes it return the given arguments as	366	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	367	status (default: the empty list). Never returns if the coroutine is the
		368	current coroutine.
257		369
258	=cut	370	=cut
259		371
260	sub cancel {	372	sub cancel {
261	my $self = shift;	373	my $self = shift;
262	$self->{status} = [@_];	374	$self->{status} = [@_];
		375
		376	if ($current == $self) {
263	push @destroy, $self;	377	push @destroy, $self;
264	$manager->ready;	378	$manager->ready;
265	&schedule if $current == $self;	379	&schedule while 1;
		380	} else {
		381	$self->_cancel;
		382	}
266	}	383	}
267		384
268	=item $process->join	385	=item $coroutine->join
269		386
270	Wait until the coroutine terminates and return any values given to the	387	Wait until the coroutine terminates and return any values given to the
271	C<terminate> or C<cancel> functions. C<join> can be called multiple times	388	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	389	from multiple coroutine.
273		390
274	=cut	391	=cut
275		392
276	sub join {	393	sub join {
277	my $self = shift;	394	my $self = shift;
		395
278	unless ($self->{status}) {	396	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	397	my $current = $current;
280	&schedule;	398
		399	push @{$self->{destroy_cb}}, sub {
		400	$current->ready;
		401	undef $current;
		402	};
		403
		404	&schedule while $current;
281	}	405	}
		406
282	wantarray ? @{$self->{status}} : $self->{status}[0];	407	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	408	}
284		409
		410	=item $coroutine->on_destroy (\&cb)
		411
		412	Registers a callback that is called when this coroutine gets destroyed,
		413	but before it is joined. The callback gets passed the terminate arguments,
		414	if any.
		415
		416	=cut
		417
		418	sub on_destroy {
		419	my ($self, $cb) = @_;
		420
		421	push @{ $self->{destroy_cb} }, $cb;
		422	}
		423
285	=item $oldprio = $process->prio ($newprio)	424	=item $oldprio = $coroutine->prio ($newprio)
286		425
287	Sets (or gets, if the argument is missing) the priority of the	426	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	427	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	428	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	429	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	430	to get then):
292		431
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	432	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	433	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	436	current->prio(PRIO_HIGH);
298		437
299	The idle coroutine ($Coro::idle) always has a lower priority than any	438	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	439	existing coroutine.
301		440
302	Changing the priority of the current process will take effect immediately,	441	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	442	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	443	running) will only take effect after the next schedule (of that
305	process). This is a bug that will be fixed in some future version.	444	coroutine). This is a bug that will be fixed in some future version.
306		445
307	=item $newprio = $process->nice ($change)	446	=item $newprio = $coroutine->nice ($change)
308		447
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	448	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	449	higher values mean lower priority, just as in unix).
311		450
312	=item $olddesc = $process->desc ($newdesc)	451	=item $olddesc = $coroutine->desc ($newdesc)
313		452
314	Sets (or gets in case the argument is missing) the description for this	453	Sets (or gets in case the argument is missing) the description for this
315	process. This is just a free-form string you can associate with a process.	454	coroutine. This is just a free-form string you can associate with a coroutine.
316		455
317	=cut	456	=cut
318		457
319	sub desc {	458	sub desc {
320	my $old = $_[0]{desc};	459	my $old = $_[0]{desc};
…		…
322	$old;	461	$old;
323	}	462	}
324		463
325	=back	464	=back
326		465
		466	=head2 GLOBAL FUNCTIONS
		467
		468	=over 4
		469
		470	=item Coro::nready
		471
		472	Returns the number of coroutines that are currently in the ready state,
		473	i.e. that can be switched to. The value C<0> means that the only runnable
		474	coroutine is the currently running one, so C<cede> would have no effect,
		475	and C<schedule> would cause a deadlock unless there is an idle handler
		476	that wakes up some coroutines.
		477
		478	=item my $guard = Coro::guard { ... }
		479
		480	This creates and returns a guard object. Nothing happens until the object
		481	gets destroyed, in which case the codeblock given as argument will be
		482	executed. This is useful to free locks or other resources in case of a
		483	runtime error or when the coroutine gets canceled, as in both cases the
		484	guard block will be executed. The guard object supports only one method,
		485	C<< ->cancel >>, which will keep the codeblock from being executed.
		486
		487	Example: set some flag and clear it again when the coroutine gets canceled
		488	or the function returns:
		489
		490	sub do_something {
		491	my $guard = Coro::guard { $busy = 0 };
		492	$busy = 1;
		493
		494	# do something that requires $busy to be true
		495	}
		496
		497	=cut
		498
		499	sub guard(&) {
		500	bless \(my $cb = $_[0]), "Coro::guard"
		501	}
		502
		503	sub Coro::guard::cancel {
		504	${$_[0]} = sub { };
		505	}
		506
		507	sub Coro::guard::DESTROY {
		508	${$_[0]}->();
		509	}
		510
		511
		512	=item unblock_sub { ... }
		513
		514	This utility function takes a BLOCK or code reference and "unblocks" it,
		515	returning the new coderef. This means that the new coderef will return
		516	immediately without blocking, returning nothing, while the original code
		517	ref will be called (with parameters) from within its own coroutine.
		518
		519	The reason this function exists is that many event libraries (such as the
		520	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		521	of thread-safety). This means you must not block within event callbacks,
		522	otherwise you might suffer from crashes or worse.
		523
		524	This function allows your callbacks to block by executing them in another
		525	coroutine where it is safe to block. One example where blocking is handy
		526	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		527	disk.
		528
		529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		530	creating event callbacks that want to block.
		531
		532	=cut
		533
		534	our @unblock_queue;
		535
		536	# we create a special coro because we want to cede,
		537	# to reduce pressure on the coro pool (because most callbacks
		538	# return immediately and can be reused) and because we cannot cede
		539	# inside an event callback.
		540	our $unblock_scheduler = new Coro sub {
		541	while () {
		542	while (my $cb = pop @unblock_queue) {
		543	# this is an inlined copy of async_pool
		544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		545
		546	$coro->{_invoke} = $cb;
		547	$coro->ready;
		548	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		549	}
		550	schedule; # sleep well
		551	}
		552	};
		553	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		554
		555	sub unblock_sub(&) {
		556	my $cb = shift;
		557
		558	sub {
		559	unshift @unblock_queue, [$cb, @_];
		560	$unblock_scheduler->ready;
		561	}
		562	}
		563
		564	=back
		565
327	=cut	566	=cut
328		567
329	1;	568	1;
330		569
331	=head1 BUGS/LIMITATIONS	570	=head1 BUGS/LIMITATIONS
332		571
333	- you must make very sure that no coro is still active on global	572	- you must make very sure that no coro is still active on global
334	destruction. very bad things might happen otherwise (usually segfaults).	573	destruction. very bad things might happen otherwise (usually segfaults).
335		574
336	- this module is not thread-safe. You should only ever use this module	575	- this module is not thread-safe. You should only ever use this module
337	from the same thread (this requirement might be losened in the future	576	from the same thread (this requirement might be loosened in the future
338	to allow per-thread schedulers, but Coro::State does not yet allow	577	to allow per-thread schedulers, but Coro::State does not yet allow
339	this).	578	this).
340		579
341	=head1 SEE ALSO	580	=head1 SEE ALSO
342		581

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Comparing Coro/Coro.pm (file contents): Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs. Revision 1.138 by root, Wed Sep 26 19:27:04 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.138 by root, Wed Sep 26 19:27:04 2007 UTC