[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 1.135 by root, Sat Sep 22 22:39:15 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 or &terminate}; # crashes, would be ~5% faster
		247	$cb = &_pool_1
		248	or &terminate;
		249	&$cb;
		250	undef $cb;
		251	&terminate if &_pool_2;
		252	&schedule;
		253	}
		254	};
		255
		256	warn $@ if $@;
		257	}
		258	}
		259
		260	sub async_pool(&@) {
		261	# this is also inlined into the unlock_scheduler
		262	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		263
		264	$coro->{_invoke} = [@_];
		265	$coro->ready;
		266
		267	$coro
190	}	268	}
191		269
192	=item schedule	270	=item schedule
193		271
194	Calls the scheduler. Please note that the current process will not be put	272	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	273	into the ready queue, so calling this function usually means you will
196	never be called again.	274	never be called again unless something else (e.g. an event handler) calls
		275	ready.
197		276
198	=cut	277	The canonical way to wait on external events is this:
		278
		279	{
		280	# remember current coroutine
		281	my $current = $Coro::current;
		282
		283	# register a hypothetical event handler
		284	on_event_invoke sub {
		285	# wake up sleeping coroutine
		286	$current->ready;
		287	undef $current;
		288	};
		289
		290	# call schedule until event occurred.
		291	# in case we are woken up for other reasons
		292	# (current still defined), loop.
		293	Coro::schedule while $current;
		294	}
199		295
200	=item cede	296	=item cede
201		297
202	"Cede" to other processes. This function puts the current process into the	298	"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	299	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.	300	current "timeslice" to other coroutines of the same or higher priority.
205		301
206	=cut	302	Returns true if at least one coroutine switch has happened.
		303
		304	=item Coro::cede_notself
		305
		306	Works like cede, but is not exported by default and will cede to any
		307	coroutine, regardless of priority, once.
		308
		309	Returns true if at least one coroutine switch has happened.
207		310
208	=item terminate [arg...]	311	=item terminate [arg...]
209		312
210	Terminates the current process with the given status values (see L<cancel>).	313	Terminates the current coroutine with the given status values (see L<cancel>).
211		314
212	=cut	315	=cut
213		316
214	sub terminate {	317	sub terminate {
215	$current->cancel (@_);	318	$current->cancel (@_);
…		…
217		320
218	=back	321	=back
219		322
220	# dynamic methods	323	# dynamic methods
221		324
222	=head2 PROCESS METHODS	325	=head2 COROUTINE METHODS
223		326
224	These are the methods you can call on process objects.	327	These are the methods you can call on coroutine objects.
225		328
226	=over 4	329	=over 4
227		330
228	=item new Coro \&sub [, @args...]	331	=item new Coro \&sub [, @args...]
229		332
230	Create a new process and return it. When the sub returns the process	333	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	334	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	335	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	336	by calling the ready method.
234		337
235	=cut	338	See C<async> for additional discussion.
236		339
		340	=cut
		341
237	sub _new_coro {	342	sub _run_coro {
238	terminate &{+shift};	343	terminate &{+shift};
239	}	344	}
240		345
241	sub new {	346	sub new {
242	my $class = shift;	347	my $class = shift;
243		348
244	$class->SUPER::new (\&_new_coro, @_)	349	$class->SUPER::new (\&_run_coro, @_)
245	}	350	}
246		351
247	=item $process->ready	352	=item $success = $coroutine->ready
248		353
249	Put the given process into the ready queue.	354	Put the given coroutine into the ready queue (according to it's priority)
		355	and return true. If the coroutine is already in the ready queue, do nothing
		356	and return false.
250		357
251	=cut	358	=item $is_ready = $coroutine->is_ready
252		359
		360	Return wether the coroutine is currently the ready queue or not,
		361
253	=item $process->cancel (arg...)	362	=item $coroutine->cancel (arg...)
254		363
255	Terminates the given process and makes it return the given arguments as	364	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	365	status (default: the empty list). Never returns if the coroutine is the
		366	current coroutine.
257		367
258	=cut	368	=cut
259		369
260	sub cancel {	370	sub cancel {
261	my $self = shift;	371	my $self = shift;
262	$self->{status} = [@_];	372	$self->{status} = [@_];
		373
		374	if ($current == $self) {
263	push @destroy, $self;	375	push @destroy, $self;
264	$manager->ready;	376	$manager->ready;
265	&schedule if $current == $self;	377	&schedule while 1;
		378	} else {
		379	$self->_cancel;
		380	}
266	}	381	}
267		382
268	=item $process->join	383	=item $coroutine->join
269		384
270	Wait until the coroutine terminates and return any values given to the	385	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	386	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	387	from multiple coroutine.
273		388
274	=cut	389	=cut
275		390
276	sub join {	391	sub join {
277	my $self = shift;	392	my $self = shift;
		393
278	unless ($self->{status}) {	394	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	395	my $current = $current;
280	&schedule;	396
		397	push @{$self->{destroy_cb}}, sub {
		398	$current->ready;
		399	undef $current;
		400	};
		401
		402	&schedule while $current;
281	}	403	}
		404
282	wantarray ? @{$self->{status}} : $self->{status}[0];	405	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	406	}
284		407
		408	=item $coroutine->on_destroy (\&cb)
		409
		410	Registers a callback that is called when this coroutine gets destroyed,
		411	but before it is joined. The callback gets passed the terminate arguments,
		412	if any.
		413
		414	=cut
		415
		416	sub on_destroy {
		417	my ($self, $cb) = @_;
		418
		419	push @{ $self->{destroy_cb} }, $cb;
		420	}
		421
285	=item $oldprio = $process->prio ($newprio)	422	=item $oldprio = $coroutine->prio ($newprio)
286		423
287	Sets (or gets, if the argument is missing) the priority of the	424	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	425	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	426	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	427	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	428	to get then):
292		429
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	430	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	431	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	434	current->prio(PRIO_HIGH);
298		435
299	The idle coroutine ($Coro::idle) always has a lower priority than any	436	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	437	existing coroutine.
301		438
302	Changing the priority of the current process will take effect immediately,	439	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	440	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	441	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.	442	coroutine). This is a bug that will be fixed in some future version.
306		443
307	=item $newprio = $process->nice ($change)	444	=item $newprio = $coroutine->nice ($change)
308		445
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	446	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	447	higher values mean lower priority, just as in unix).
311		448
312	=item $olddesc = $process->desc ($newdesc)	449	=item $olddesc = $coroutine->desc ($newdesc)
313		450
314	Sets (or gets in case the argument is missing) the description for this	451	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.	452	coroutine. This is just a free-form string you can associate with a coroutine.
316		453
317	=cut	454	=cut
318		455
319	sub desc {	456	sub desc {
320	my $old = $_[0]{desc};	457	my $old = $_[0]{desc};
…		…
322	$old;	459	$old;
323	}	460	}
324		461
325	=back	462	=back
326		463
		464	=head2 GLOBAL FUNCTIONS
		465
		466	=over 4
		467
		468	=item Coro::nready
		469
		470	Returns the number of coroutines that are currently in the ready state,
		471	i.e. that can be switched to. The value C<0> means that the only runnable
		472	coroutine is the currently running one, so C<cede> would have no effect,
		473	and C<schedule> would cause a deadlock unless there is an idle handler
		474	that wakes up some coroutines.
		475
		476	=item my $guard = Coro::guard { ... }
		477
		478	This creates and returns a guard object. Nothing happens until the object
		479	gets destroyed, in which case the codeblock given as argument will be
		480	executed. This is useful to free locks or other resources in case of a
		481	runtime error or when the coroutine gets canceled, as in both cases the
		482	guard block will be executed. The guard object supports only one method,
		483	C<< ->cancel >>, which will keep the codeblock from being executed.
		484
		485	Example: set some flag and clear it again when the coroutine gets canceled
		486	or the function returns:
		487
		488	sub do_something {
		489	my $guard = Coro::guard { $busy = 0 };
		490	$busy = 1;
		491
		492	# do something that requires $busy to be true
		493	}
		494
		495	=cut
		496
		497	sub guard(&) {
		498	bless \(my $cb = $_[0]), "Coro::guard"
		499	}
		500
		501	sub Coro::guard::cancel {
		502	${$_[0]} = sub { };
		503	}
		504
		505	sub Coro::guard::DESTROY {
		506	${$_[0]}->();
		507	}
		508
		509
		510	=item unblock_sub { ... }
		511
		512	This utility function takes a BLOCK or code reference and "unblocks" it,
		513	returning the new coderef. This means that the new coderef will return
		514	immediately without blocking, returning nothing, while the original code
		515	ref will be called (with parameters) from within its own coroutine.
		516
		517	The reason this function exists is that many event libraries (such as the
		518	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		519	of thread-safety). This means you must not block within event callbacks,
		520	otherwise you might suffer from crashes or worse.
		521
		522	This function allows your callbacks to block by executing them in another
		523	coroutine where it is safe to block. One example where blocking is handy
		524	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		525	disk.
		526
		527	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		528	creating event callbacks that want to block.
		529
		530	=cut
		531
		532	our @unblock_queue;
		533
		534	# we create a special coro because we want to cede,
		535	# to reduce pressure on the coro pool (because most callbacks
		536	# return immediately and can be reused) and because we cannot cede
		537	# inside an event callback.
		538	our $unblock_scheduler = new Coro sub {
		539	while () {
		540	while (my $cb = pop @unblock_queue) {
		541	# this is an inlined copy of async_pool
		542	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		543
		544	$coro->{_invoke} = $cb;
		545	$coro->ready;
		546	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		547	}
		548	schedule; # sleep well
		549	}
		550	};
		551	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		552
		553	sub unblock_sub(&) {
		554	my $cb = shift;
		555
		556	sub {
		557	unshift @unblock_queue, [$cb, @_];
		558	$unblock_scheduler->ready;
		559	}
		560	}
		561
		562	=back
		563
327	=cut	564	=cut
328		565
329	1;	566	1;
330		567
331	=head1 BUGS/LIMITATIONS	568	=head1 BUGS/LIMITATIONS
332		569
333	- you must make very sure that no coro is still active on global	570	- you must make very sure that no coro is still active on global
334	destruction. very bad things might happen otherwise (usually segfaults).	571	destruction. very bad things might happen otherwise (usually segfaults).
335		572
336	- this module is not thread-safe. You should only ever use this module	573	- 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	574	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	575	to allow per-thread schedulers, but Coro::State does not yet allow
339	this).	576	this).
340		577
341	=head1 SEE ALSO	578	=head1 SEE ALSO
342		579

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 1.135 by root, Sat Sep 22 22:39:15 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 1.135 by root, Sat Sep 22 22:39:15 2007 UTC