[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 1.136 by root, Sat Sep 22 22:59:31 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 $VERSION = '3.7';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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	}
134		159
135	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	161	# cannot destroy itself.
137	my @destroy;	162	my @destroy;
		163	my $manager;
		164
138	my $manager; $manager = new Coro sub {	165	$manager = new Coro sub {
139	while () {	166	while () {
140	# by overwriting the state object with the manager we destroy it	167	(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) {	168	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		169
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;	170	&schedule;
157	}	171	}
158	};	172	};
		173	$manager->desc ("[coro manager]");
		174	$manager->prio (PRIO_MAX);
159		175
160	# static methods. not really.	176	# static methods. not really.
161		177
162	=back	178	=back
163		179
164	=head2 STATIC METHODS	180	=head2 STATIC METHODS
165		181
166	Static methods are actually functions that operate on the current process only.	182	Static methods are actually functions that operate on the current coroutine only.
167		183
168	=over 4	184	=over 4
169		185
170	=item async { ... } [@args...]	186	=item async { ... } [@args...]
171		187
172	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	190	terminated.
175		191
176	When the coroutine dies, the program will exit, just as in the main	192	Calling C<exit> in a coroutine will do the same as calling exit outside
177	program.	193	the coroutine. Likewise, when the coroutine dies, the program will exit,
		194	just as it would in the main program.
178		195
179	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
180	async {	197	async {
181	print "@_\n";	198	print "@_\n";
182	} 1,2,3,4;	199	} 1,2,3,4;
183		200
184	=cut	201	=cut
185		202
186	sub async(&@) {	203	sub async(&@) {
187	my $pid = new Coro @_;	204	my $coro = new Coro @_;
188	$pid->ready;	205	$coro->ready;
189	$pid	206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		230	{ terminate }> once per second or so to slowly replenish the pool. In
		231	addition to that, when the stacks used by a handler grows larger than 16kb
		232	(adjustable with $Coro::POOL_RSS) it will also exit.
		233
		234	=cut
		235
		236	our $POOL_SIZE = 8;
		237	our $POOL_RSS = 16 * 1024;
		238	our @async_pool;
		239
		240	sub pool_handler {
		241	my $cb;
		242
		243	while () {
		244	eval {
		245	while () {
		246	_pool_1 $cb;
		247	&$cb;
		248	_pool_2 $cb;
		249	&schedule;
		250	}
		251	};
		252
		253	last if $@ eq "\3terminate\2\n";
		254	warn $@ if $@;
		255	}
		256	}
		257
		258	sub async_pool(&@) {
		259	# this is also inlined into the unlock_scheduler
		260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		261
		262	$coro->{_invoke} = [@_];
		263	$coro->ready;
		264
		265	$coro
190	}	266	}
191		267
192	=item schedule	268	=item schedule
193		269
194	Calls the scheduler. Please note that the current process will not be put	270	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	271	into the ready queue, so calling this function usually means you will
196	never be called again.	272	never be called again unless something else (e.g. an event handler) calls
		273	ready.
197		274
198	=cut	275	The canonical way to wait on external events is this:
		276
		277	{
		278	# remember current coroutine
		279	my $current = $Coro::current;
		280
		281	# register a hypothetical event handler
		282	on_event_invoke sub {
		283	# wake up sleeping coroutine
		284	$current->ready;
		285	undef $current;
		286	};
		287
		288	# call schedule until event occurred.
		289	# in case we are woken up for other reasons
		290	# (current still defined), loop.
		291	Coro::schedule while $current;
		292	}
199		293
200	=item cede	294	=item cede
201		295
202	"Cede" to other processes. This function puts the current process into the	296	"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	297	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.	298	current "timeslice" to other coroutines of the same or higher priority.
205		299
206	=cut	300	Returns true if at least one coroutine switch has happened.
		301
		302	=item Coro::cede_notself
		303
		304	Works like cede, but is not exported by default and will cede to any
		305	coroutine, regardless of priority, once.
		306
		307	Returns true if at least one coroutine switch has happened.
207		308
208	=item terminate [arg...]	309	=item terminate [arg...]
209		310
210	Terminates the current process with the given status values (see L<cancel>).	311	Terminates the current coroutine with the given status values (see L<cancel>).
211		312
212	=cut	313	=cut
213		314
214	sub terminate {	315	sub terminate {
215	$current->cancel (@_);	316	$current->cancel (@_);
…		…
217		318
218	=back	319	=back
219		320
220	# dynamic methods	321	# dynamic methods
221		322
222	=head2 PROCESS METHODS	323	=head2 COROUTINE METHODS
223		324
224	These are the methods you can call on process objects.	325	These are the methods you can call on coroutine objects.
225		326
226	=over 4	327	=over 4
227		328
228	=item new Coro \&sub [, @args...]	329	=item new Coro \&sub [, @args...]
229		330
230	Create a new process and return it. When the sub returns the process	331	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	332	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	333	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	334	by calling the ready method.
234		335
235	=cut	336	See C<async> for additional discussion.
236		337
		338	=cut
		339
237	sub _new_coro {	340	sub _run_coro {
238	terminate &{+shift};	341	terminate &{+shift};
239	}	342	}
240		343
241	sub new {	344	sub new {
242	my $class = shift;	345	my $class = shift;
243		346
244	$class->SUPER::new (\&_new_coro, @_)	347	$class->SUPER::new (\&_run_coro, @_)
245	}	348	}
246		349
247	=item $process->ready	350	=item $success = $coroutine->ready
248		351
249	Put the given process into the ready queue.	352	Put the given coroutine into the ready queue (according to it's priority)
		353	and return true. If the coroutine is already in the ready queue, do nothing
		354	and return false.
250		355
251	=cut	356	=item $is_ready = $coroutine->is_ready
252		357
		358	Return wether the coroutine is currently the ready queue or not,
		359
253	=item $process->cancel (arg...)	360	=item $coroutine->cancel (arg...)
254		361
255	Terminates the given process and makes it return the given arguments as	362	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	363	status (default: the empty list). Never returns if the coroutine is the
		364	current coroutine.
257		365
258	=cut	366	=cut
259		367
260	sub cancel {	368	sub cancel {
261	my $self = shift;	369	my $self = shift;
262	$self->{status} = [@_];	370	$self->{status} = [@_];
		371
		372	if ($current == $self) {
263	push @destroy, $self;	373	push @destroy, $self;
264	$manager->ready;	374	$manager->ready;
265	&schedule if $current == $self;	375	&schedule while 1;
		376	} else {
		377	$self->_cancel;
		378	}
266	}	379	}
267		380
268	=item $process->join	381	=item $coroutine->join
269		382
270	Wait until the coroutine terminates and return any values given to the	383	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	384	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	385	from multiple coroutine.
273		386
274	=cut	387	=cut
275		388
276	sub join {	389	sub join {
277	my $self = shift;	390	my $self = shift;
		391
278	unless ($self->{status}) {	392	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	393	my $current = $current;
280	&schedule;	394
		395	push @{$self->{destroy_cb}}, sub {
		396	$current->ready;
		397	undef $current;
		398	};
		399
		400	&schedule while $current;
281	}	401	}
		402
282	wantarray ? @{$self->{status}} : $self->{status}[0];	403	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	404	}
284		405
		406	=item $coroutine->on_destroy (\&cb)
		407
		408	Registers a callback that is called when this coroutine gets destroyed,
		409	but before it is joined. The callback gets passed the terminate arguments,
		410	if any.
		411
		412	=cut
		413
		414	sub on_destroy {
		415	my ($self, $cb) = @_;
		416
		417	push @{ $self->{destroy_cb} }, $cb;
		418	}
		419
285	=item $oldprio = $process->prio ($newprio)	420	=item $oldprio = $coroutine->prio ($newprio)
286		421
287	Sets (or gets, if the argument is missing) the priority of the	422	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	423	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	424	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	425	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	426	to get then):
292		427
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	428	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	429	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	432	current->prio(PRIO_HIGH);
298		433
299	The idle coroutine ($Coro::idle) always has a lower priority than any	434	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	435	existing coroutine.
301		436
302	Changing the priority of the current process will take effect immediately,	437	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	438	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	439	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.	440	coroutine). This is a bug that will be fixed in some future version.
306		441
307	=item $newprio = $process->nice ($change)	442	=item $newprio = $coroutine->nice ($change)
308		443
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	444	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	445	higher values mean lower priority, just as in unix).
311		446
312	=item $olddesc = $process->desc ($newdesc)	447	=item $olddesc = $coroutine->desc ($newdesc)
313		448
314	Sets (or gets in case the argument is missing) the description for this	449	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.	450	coroutine. This is just a free-form string you can associate with a coroutine.
316		451
317	=cut	452	=cut
318		453
319	sub desc {	454	sub desc {
320	my $old = $_[0]{desc};	455	my $old = $_[0]{desc};
…		…
322	$old;	457	$old;
323	}	458	}
324		459
325	=back	460	=back
326		461
		462	=head2 GLOBAL FUNCTIONS
		463
		464	=over 4
		465
		466	=item Coro::nready
		467
		468	Returns the number of coroutines that are currently in the ready state,
		469	i.e. that can be switched to. The value C<0> means that the only runnable
		470	coroutine is the currently running one, so C<cede> would have no effect,
		471	and C<schedule> would cause a deadlock unless there is an idle handler
		472	that wakes up some coroutines.
		473
		474	=item my $guard = Coro::guard { ... }
		475
		476	This creates and returns a guard object. Nothing happens until the object
		477	gets destroyed, in which case the codeblock given as argument will be
		478	executed. This is useful to free locks or other resources in case of a
		479	runtime error or when the coroutine gets canceled, as in both cases the
		480	guard block will be executed. The guard object supports only one method,
		481	C<< ->cancel >>, which will keep the codeblock from being executed.
		482
		483	Example: set some flag and clear it again when the coroutine gets canceled
		484	or the function returns:
		485
		486	sub do_something {
		487	my $guard = Coro::guard { $busy = 0 };
		488	$busy = 1;
		489
		490	# do something that requires $busy to be true
		491	}
		492
		493	=cut
		494
		495	sub guard(&) {
		496	bless \(my $cb = $_[0]), "Coro::guard"
		497	}
		498
		499	sub Coro::guard::cancel {
		500	${$_[0]} = sub { };
		501	}
		502
		503	sub Coro::guard::DESTROY {
		504	${$_[0]}->();
		505	}
		506
		507
		508	=item unblock_sub { ... }
		509
		510	This utility function takes a BLOCK or code reference and "unblocks" it,
		511	returning the new coderef. This means that the new coderef will return
		512	immediately without blocking, returning nothing, while the original code
		513	ref will be called (with parameters) from within its own coroutine.
		514
		515	The reason this function exists is that many event libraries (such as the
		516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		517	of thread-safety). This means you must not block within event callbacks,
		518	otherwise you might suffer from crashes or worse.
		519
		520	This function allows your callbacks to block by executing them in another
		521	coroutine where it is safe to block. One example where blocking is handy
		522	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		523	disk.
		524
		525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		526	creating event callbacks that want to block.
		527
		528	=cut
		529
		530	our @unblock_queue;
		531
		532	# we create a special coro because we want to cede,
		533	# to reduce pressure on the coro pool (because most callbacks
		534	# return immediately and can be reused) and because we cannot cede
		535	# inside an event callback.
		536	our $unblock_scheduler = new Coro sub {
		537	while () {
		538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
		540	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		541
		542	$coro->{_invoke} = $cb;
		543	$coro->ready;
		544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		545	}
		546	schedule; # sleep well
		547	}
		548	};
		549	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		550
		551	sub unblock_sub(&) {
		552	my $cb = shift;
		553
		554	sub {
		555	unshift @unblock_queue, [$cb, @_];
		556	$unblock_scheduler->ready;
		557	}
		558	}
		559
		560	=back
		561
327	=cut	562	=cut
328		563
329	1;	564	1;
330		565
331	=head1 BUGS/LIMITATIONS	566	=head1 BUGS/LIMITATIONS
332		567
333	- you must make very sure that no coro is still active on global	568	- you must make very sure that no coro is still active on global
334	destruction. very bad things might happen otherwise (usually segfaults).	569	destruction. very bad things might happen otherwise (usually segfaults).
335		570
336	- this module is not thread-safe. You should only ever use this module	571	- 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	572	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	573	to allow per-thread schedulers, but Coro::State does not yet allow
339	this).	574	this).
340		575
341	=head1 SEE ALSO	576	=head1 SEE ALSO
342		577

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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 1.136 by root, Sat Sep 22 22:59:31 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 1.136 by root, Sat Sep 22 22:59:31 2007 UTC