[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 1.111 by root, Sun Jan 14 21:13:48 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
		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 $VERSION = '3.4';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$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, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
109	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
112	}	120	if $current;
113		121
114	$current = $main;	122	_set_current $main;
115		123
116	sub current() { $current }	124	sub current() { $current }
117		125
118	=item $idle	126	=item $idle
119		127
120	A callback that is called whenever the scheduler finds no ready coroutines	128	A callback that is called whenever the scheduler finds no ready coroutines
121	to run. The default implementation prints "FATAL: deadlock detected" and	129	to run. The default implementation prints "FATAL: deadlock detected" and
122	exits.	130	exits, because the program has no other way to continue.
123		131
124	This hook is overwritten by modules such as C<Coro::Timer> and	132	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	133	C<Coro::Event> to wait on an external event that hopefully wake up a
126	coroutine.	134	coroutine so the scheduler can run it.
		135
		136	Please note that if your callback recursively invokes perl (e.g. for event
		137	handlers), then it must be prepared to be called recursively.
127		138
128	=cut	139	=cut
129		140
130	$idle = sub {	141	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	142	require Carp;
132	exit (51);	143	Carp::croak ("FATAL: deadlock detected");
133	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
134		157
135	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	159	# cannot destroy itself.
137	my @destroy;	160	my @destroy;
		161	my $manager;
		162
138	my $manager; $manager = new Coro sub {	163	$manager = new Coro sub {
139	while () {	164	while () {
140	# by overwriting the state object with the manager we destroy it	165	(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) {	166	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		167
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;	168	&schedule;
157	}	169	}
158	};	170	};
159		171
		172	$manager->prio (PRIO_MAX);
		173
160	# static methods. not really.	174	# static methods. not really.
161		175
162	=back	176	=back
163		177
164	=head2 STATIC METHODS	178	=head2 STATIC METHODS
165		179
166	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.
167		181
168	=over 4	182	=over 4
169		183
170	=item async { ... } [@args...]	184	=item async { ... } [@args...]
171		185
172	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
175		191
176	When the coroutine dies, the program will exit, just as in the main	192	When the coroutine dies, the program will exit, just as in the main
177	program.	193	program.
178		194
179	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
…		…
182	} 1,2,3,4;	198	} 1,2,3,4;
183		199
184	=cut	200	=cut
185		201
186	sub async(&@) {	202	sub async(&@) {
187	my $pid = new Coro @_;	203	my $coro = new Coro @_;
188	$pid->ready;	204	$coro->ready;
189	$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
		216	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		217	will not work in the expected way, unless you call terminate or cancel,
		218	which somehow defeats the purpose of pooling.
		219
		220	The priority will be reset to C<0> after each job, otherwise the coroutine
		221	will be re-used "as-is".
		222
		223	The pool size is limited to 8 idle coroutines (this can be adjusted by
		224	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		225	required.
		226
		227	If you are concerned about pooled coroutines growing a lot because a
		228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		229	terminate }> once per second or so to slowly replenish the pool.
		230
		231	=cut
		232
		233	our $POOL_SIZE = 8;
		234	our @pool;
		235
		236	sub pool_handler {
		237	while () {
		238	eval {
		239	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		240	$cb->(@arg);
		241	};
		242	warn $@ if $@;
		243
		244	last if @pool >= $POOL_SIZE;
		245	push @pool, $current;
		246
		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
190	}	260	}
191		261
192	=item schedule	262	=item schedule
193		263
194	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
195	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
196	never be called again.	266	never be called again unless something else (e.g. an event handler) calls
		267	ready.
197		268
198	=cut	269	The canonical way to wait on external events is this:
		270
		271	{
		272	# remember current coroutine
		273	my $current = $Coro::current;
		274
		275	# register a hypothetical event handler
		276	on_event_invoke sub {
		277	# wake up sleeping coroutine
		278	$current->ready;
		279	undef $current;
		280	};
		281
		282	# call schedule until event occured.
		283	# in case we are woken up for other reasons
		284	# (current still defined), loop.
		285	Coro::schedule while $current;
		286	}
199		287
200	=item cede	288	=item cede
201		289
202	"Cede" to other processes. This function puts the current process into the	290	"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	291	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.	292	current "timeslice" to other coroutines of the same or higher priority.
205		293
206	=cut	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.
207		302
208	=item terminate [arg...]	303	=item terminate [arg...]
209		304
210	Terminates the current process with the given status values (see L<cancel>).	305	Terminates the current coroutine with the given status values (see L<cancel>).
211		306
212	=cut	307	=cut
213		308
214	sub terminate {	309	sub terminate {
215	$current->cancel (@_);	310	$current->cancel (@_);
…		…
217		312
218	=back	313	=back
219		314
220	# dynamic methods	315	# dynamic methods
221		316
222	=head2 PROCESS METHODS	317	=head2 COROUTINE METHODS
223		318
224	These are the methods you can call on process objects.	319	These are the methods you can call on coroutine objects.
225		320
226	=over 4	321	=over 4
227		322
228	=item new Coro \&sub [, @args...]	323	=item new Coro \&sub [, @args...]
229		324
230	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
231	automatically terminates as if C<terminate> with the returned values were	326	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	327	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	328	by calling the ready method.
234		329
235	=cut	330	Calling C<exit> in a coroutine will not work correctly, so do not do that.
236		331
		332	=cut
		333
237	sub _new_coro {	334	sub _run_coro {
238	terminate &{+shift};	335	terminate &{+shift};
239	}	336	}
240		337
241	sub new {	338	sub new {
242	my $class = shift;	339	my $class = shift;
243		340
244	$class->SUPER::new (\&_new_coro, @_)	341	$class->SUPER::new (\&_run_coro, @_)
245	}	342	}
246		343
247	=item $process->ready	344	=item $success = $coroutine->ready
248		345
249	Put the given process into the ready queue.	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.
250		349
251	=cut	350	=item $is_ready = $coroutine->is_ready
252		351
		352	Return wether the coroutine is currently the ready queue or not,
		353
253	=item $process->cancel (arg...)	354	=item $coroutine->cancel (arg...)
254		355
255	Terminates the given process and makes it return the given arguments as	356	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	357	status (default: the empty list). Never returns if the coroutine is the
		358	current coroutine.
257		359
258	=cut	360	=cut
259		361
260	sub cancel {	362	sub cancel {
261	my $self = shift;	363	my $self = shift;
262	$self->{status} = [@_];	364	$self->{status} = [@_];
		365
		366	if ($current == $self) {
263	push @destroy, $self;	367	push @destroy, $self;
264	$manager->ready;	368	$manager->ready;
265	&schedule if $current == $self;	369	&schedule while 1;
		370	} else {
		371	$self->_cancel;
		372	}
266	}	373	}
267		374
268	=item $process->join	375	=item $coroutine->join
269		376
270	Wait until the coroutine terminates and return any values given to the	377	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	378	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	379	from multiple coroutine.
273		380
274	=cut	381	=cut
275		382
276	sub join {	383	sub join {
277	my $self = shift;	384	my $self = shift;
		385
278	unless ($self->{status}) {	386	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	387	my $current = $current;
280	&schedule;	388
		389	push @{$self->{destroy_cb}}, sub {
		390	$current->ready;
		391	undef $current;
		392	};
		393
		394	&schedule while $current;
281	}	395	}
		396
282	wantarray ? @{$self->{status}} : $self->{status}[0];	397	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	398	}
284		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
285	=item $oldprio = $process->prio ($newprio)	414	=item $oldprio = $coroutine->prio ($newprio)
286		415
287	Sets (or gets, if the argument is missing) the priority of the	416	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	417	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	418	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	419	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	420	to get then):
292		421
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	422	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	423	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	426	current->prio(PRIO_HIGH);
298		427
299	The idle coroutine ($Coro::idle) always has a lower priority than any	428	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	429	existing coroutine.
301		430
302	Changing the priority of the current process will take effect immediately,	431	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	432	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	433	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.	434	coroutine). This is a bug that will be fixed in some future version.
306		435
307	=item $newprio = $process->nice ($change)	436	=item $newprio = $coroutine->nice ($change)
308		437
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	438	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	439	higher values mean lower priority, just as in unix).
311		440
312	=item $olddesc = $process->desc ($newdesc)	441	=item $olddesc = $coroutine->desc ($newdesc)
313		442
314	Sets (or gets in case the argument is missing) the description for this	443	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.	444	coroutine. This is just a free-form string you can associate with a coroutine.
316		445
317	=cut	446	=cut
318		447
319	sub desc {	448	sub desc {
320	my $old = $_[0]{desc};	449	my $old = $_[0]{desc};
…		…
322	$old;	451	$old;
323	}	452	}
324		453
325	=back	454	=back
326		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 swicthed 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 objetc
		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 fucntion 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
327	=cut	555	=cut
328		556
329	1;	557	1;
330		558
331	=head1 BUGS/LIMITATIONS	559	=head1 BUGS/LIMITATIONS

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs. Revision 1.111 by root, Sun Jan 14 21:13:48 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.111 by root, Sun Jan 14 21:13:48 2007 UTC