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

Comparing Coro/Coro.pm (file contents):
Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC vs.
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC

…		…
2		2
3	Coro - coroutine process abstraction	3	Coro - coroutine process abstraction
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coroutine
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	This module collection manages coroutines. Coroutines are similar to
24	to threads but don't run in parallel at the same time even on SMP	32	threads but don't (in general) run in parallel at the same time even
25	machines. The specific flavor of coroutine use din this module also	33	on SMP machines. The specific flavor of coroutine used in this module
26	guarentees you that it will not switch between coroutines unless	34	also guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and	35	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much	36	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.	37	safer and easier than threads programming.
30		38
31	(Perl, however, does not natively support real threads but instead does a	39	Unlike a normal perl program, however, coroutines allow you to have
32	very slow and memory-intensive emulation of processes using threads. This	40	multiple running interpreters that share data, which is especially useful
33	is a performance win on Windows machines, and a loss everywhere else).	41	to code pseudo-parallel processes and for event-based programming, such as
		42	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to
		43	learn more.
		44
		45	Coroutines are also useful because Perl has no support for threads (the so
		46	called "threads" that perl offers are nothing more than the (bad) process
		47	emulation coming from the Windows platform: On standard operating systems
		48	they serve no purpose whatsoever, except by making your programs slow and
		49	making them use a lot of memory. Best disable them when building perl, or
		50	aks your software vendor/distributor to do it for you).
34		51
35	In this module, coroutines are defined as "callchain + lexical variables +	52	In this module, coroutines are defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
37	its own set of lexicals and its own set of perls most important global	54	its own set of lexicals and its own set of perls most important global
38	variables.	55	variables (see L<Coro::State> for more configuration).
39		56
40	=cut	57	=cut
41		58
42	package Coro;	59	package Coro;
43		60
…		…
50		67
51	our $idle; # idle handler	68	our $idle; # idle handler
52	our $main; # main coroutine	69	our $main; # main coroutine
53	our $current; # current coroutine	70	our $current; # current coroutine
54		71
55	our $VERSION = '3.3';	72	our $VERSION = 4.8;
56		73
57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	77	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		79
63	{
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96
97	=over 4	80	=over 4
98		81
99	=item $main	82	=item $Coro::main
100		83
101	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
102		88
103	=cut	89	=cut
104		90
105	$main = new Coro;	91	$main = new Coro;
106		92
107	=item $current (or as function: current)	93	=item $Coro::current
108		94
109	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	97	C<$main> (of course).
111		98
112	This variable is B<strictly> I<read-only>. It is provided for performance	99	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essentiel you are encouraged to use the	100	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
115		102
116	=cut	103	=cut
		104
		105	$main->{desc} = "[main::]";
117		106
118	# maybe some other module used Coro::Specific before...	107	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}	108	$main->{_specific} = $current->{_specific}
120	if $current;	109	if $current;
121		110
122	_set_current $main;	111	_set_current $main;
123		112
124	sub current() { $current }	113	sub current() { $current } # [DEPRECATED]
125		114
126	=item $idle	115	=item $Coro::idle
127		116
128	A callback that is called whenever the scheduler finds no ready coroutines	117	This variable is mainly useful to integrate Coro into event loops. It is
129	to run. The default implementation prints "FATAL: deadlock detected" and	118	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
130	exits, because the program has no other way to continue.	119	pretty low-level functionality.
		120
		121	This variable stores a callback that is called whenever the scheduler
		122	finds no ready coroutines to run. The default implementation prints
		123	"FATAL: deadlock detected" and exits, because the program has no other way
		124	to continue.
131		125
132	This hook is overwritten by modules such as C<Coro::Timer> and	126	This hook is overwritten by modules such as C<Coro::Timer> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a	127	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.	128	coroutine so the scheduler can run it.
135		129
		130	Note that the callback I<must not>, under any circumstances, block
		131	the current coroutine. Normally, this is achieved by having an "idle
		132	coroutine" that calls the event loop and then blocks again, and then
		133	readying that coroutine in the idle handler.
		134
		135	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		136	technique.
		137
136	Please note that if your callback recursively invokes perl (e.g. for event	138	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively itself.
138		140
139	=cut	141	=cut
140		142
141	$idle = sub {	143	$idle = sub {
142	require Carp;	144	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	145	Carp::croak ("FATAL: deadlock detected");
144	};	146	};
145		147
		148	sub _cancel {
		149	my ($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->{_on_destroy}) \|\| []};
		158	}
		159
146	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
147	# cannot destroy itself.	161	# cannot destroy itself.
148	my @destroy;	162	my @destroy;
		163	my $manager;
		164
149	my $manager; $manager = new Coro sub {	165	$manager = new Coro sub {
150	while () {	166	while () {
151	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
152	# while still being able to schedule this coroutine (in case it has
153	# been readied multiple times. this is harmless since the manager
154	# can be called as many times as neccessary and will always
155	# remove itself from the runqueue
156	while (@destroy) {	168	while @destroy;
157	my $coro = pop @destroy;
158		169
159	$coro->{status} \|\|= [];
160
161	$_->ready for @{(delete $coro->{join} ) \|\| []};
162	$_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) \|\| []};
163
164	# the next line destroys the coro state, but keeps the
165	# coroutine itself intact (we basically make it a zombie
166	# coroutine that always runs the manager thread, so it's possible
167	# to transfer() to this coroutine).
168	$coro->_clone_state_from ($manager);
169	}
170	&schedule;	170	&schedule;
171	}	171	}
172	};	172	};
173		173	$manager->desc ("[coro manager]");
174	# static methods. not really.	174	$manager->prio (PRIO_MAX);
175		175
176	=back	176	=back
177		177
178	=head2 STATIC METHODS	178	=head2 SIMPLE COROUTINE CREATION
179
180	Static methods are actually functions that operate on the current coroutine only.
181		179
182	=over 4	180	=over 4
183		181
184	=item async { ... } [@args...]	182	=item async { ... } [@args...]
185		183
186	Create a new asynchronous coroutine and return it's coroutine object	184	Create a new coroutine and return it's coroutine object (usually
187	(usually unused). When the sub returns the new coroutine is automatically	185	unused). The coroutine will be put into the ready queue, so
		186	it will start running automatically on the next scheduler run.
		187
		188	The first argument is a codeblock/closure that should be executed in the
		189	coroutine. When it returns argument returns the coroutine is automatically
188	terminated.	190	terminated.
189		191
190	Calling C<exit> in a coroutine will not work correctly, so do not do that.	192	The remaining arguments are passed as arguments to the closure.
191		193
192	When the coroutine dies, the program will exit, just as in the main	194	See the C<Coro::State::new> constructor for info about the coroutine
193	program.	195	environment in which coroutines are executed.
194		196
		197	Calling C<exit> in a coroutine will do the same as calling exit outside
		198	the coroutine. Likewise, when the coroutine dies, the program will exit,
		199	just as it would in the main program.
		200
		201	If you do not want that, you can provide a default C<die> handler, or
		202	simply avoid dieing (by use of C<eval>).
		203
195	# create a new coroutine that just prints its arguments	204	Example: Create a new coroutine that just prints its arguments.
		205
196	async {	206	async {
197	print "@_\n";	207	print "@_\n";
198	} 1,2,3,4;	208	} 1,2,3,4;
199		209
200	=cut	210	=cut
201		211
202	sub async(&@) {	212	sub async(&@) {
203	my $pid = new Coro @_;	213	my $coro = new Coro @_;
204	$pid->ready;	214	$coro->ready;
205	$pid	215	$coro
206	}	216	}
		217
		218	=item async_pool { ... } [@args...]
		219
		220	Similar to C<async>, but uses a coroutine pool, so you should not call
		221	terminate or join on it (although you are allowed to), and you get a
		222	coroutine that might have executed other code already (which can be good
		223	or bad :).
		224
		225	On the plus side, this function is faster than creating (and destroying)
		226	a completely new coroutine, so if you need a lot of generic coroutines in
		227	quick successsion, use C<async_pool>, not C<async>.
		228
		229	The code block is executed in an C<eval> context and a warning will be
		230	issued in case of an exception instead of terminating the program, as
		231	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		232	will not work in the expected way, unless you call terminate or cancel,
		233	which somehow defeats the purpose of pooling (but is fine in the
		234	exceptional case).
		235
		236	The priority will be reset to C<0> after each run, tracing will be
		237	disabled, the description will be reset and the default output filehandle
		238	gets restored, so you can change all these. Otherwise the coroutine will
		239	be re-used "as-is": most notably if you change other per-coroutine global
		240	stuff such as C<$/> you I<must needs> to revert that change, which is most
		241	simply done by using local as in: C< local $/ >.
		242
		243	The pool size is limited to C<8> idle coroutines (this can be adjusted by
		244	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		245	required.
		246
		247	If you are concerned about pooled coroutines growing a lot because a
		248	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		249	{ terminate }> once per second or so to slowly replenish the pool. In
		250	addition to that, when the stacks used by a handler grows larger than 16kb
		251	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		252
		253	=cut
		254
		255	our $POOL_SIZE = 8;
		256	our $POOL_RSS = 16 * 1024;
		257	our @async_pool;
		258
		259	sub pool_handler {
		260	my $cb;
		261
		262	while () {
		263	eval {
		264	while () {
		265	_pool_1 $cb;
		266	&$cb;
		267	_pool_2 $cb;
		268	&schedule;
		269	}
		270	};
		271
		272	if ($@) {
		273	last if $@ eq "\3async_pool terminate\2\n";
		274	warn $@;
		275	}
		276	}
		277	}
		278
		279	sub async_pool(&@) {
		280	# this is also inlined into the unlock_scheduler
		281	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		282
		283	$coro->{_invoke} = [@_];
		284	$coro->ready;
		285
		286	$coro
		287	}
		288
		289	=back
		290
		291	=head2 STATIC METHODS
		292
		293	Static methods are actually functions that operate on the current coroutine.
		294
		295	=over 4
207		296
208	=item schedule	297	=item schedule
209		298
210	Calls the scheduler. Please note that the current coroutine will not be put	299	Calls the scheduler. The scheduler will find the next coroutine that is
		300	to be run from the ready queue and switches to it. The next coroutine
		301	to be run is simply the one with the highest priority that is longest
		302	in its ready queue. If there is no coroutine ready, it will clal the
		303	C<$Coro::idle> hook.
		304
		305	Please note that the current coroutine will I<not> be put into the ready
211	into the ready queue, so calling this function usually means you will	306	queue, so calling this function usually means you will never be called
212	never be called again unless something else (e.g. an event handler) calls	307	again unless something else (e.g. an event handler) calls C<< ->ready >>,
213	ready.	308	thus waking you up.
		309
		310	This makes C<schedule> I<the> generic method to use to block the current
		311	coroutine and wait for events: first you remember the current coroutine in
		312	a variable, then arrange for some callback of yours to call C<< ->ready
		313	>> on that once some event happens, and last you call C<schedule> to put
		314	yourself to sleep. Note that a lot of things can wake your coroutine up,
		315	so you need to check whether the event indeed happened, e.g. by storing the
		316	status in a variable.
214		317
215	The canonical way to wait on external events is this:	318	The canonical way to wait on external events is this:
216		319
217	{	320	{
218	# remember current coroutine	321	# remember current coroutine
…		…
223	# wake up sleeping coroutine	326	# wake up sleeping coroutine
224	$current->ready;	327	$current->ready;
225	undef $current;	328	undef $current;
226	};	329	};
227		330
228	# call schedule until event occured.	331	# call schedule until event occurred.
229	# in case we are woken up for other reasons	332	# in case we are woken up for other reasons
230	# (current still defined), loop.	333	# (current still defined), loop.
231	Coro::schedule while $current;	334	Coro::schedule while $current;
232	}	335	}
233		336
234	=item cede	337	=item cede
235		338
236	"Cede" to other coroutines. This function puts the current coroutine into the	339	"Cede" to other coroutines. This function puts the current coroutine into
237	ready queue and calls C<schedule>, which has the effect of giving up the	340	the ready queue and calls C<schedule>, which has the effect of giving
238	current "timeslice" to other coroutines of the same or higher priority.	341	up the current "timeslice" to other coroutines of the same or higher
		342	priority. Once your coroutine gets its turn again it will automatically be
		343	resumed.
		344
		345	This function is often called C<yield> in other languages.
239		346
240	=item Coro::cede_notself	347	=item Coro::cede_notself
241		348
242	Works like cede, but is not exported by default and will cede to any	349	Works like cede, but is not exported by default and will cede to I<any>
243	coroutine, regardless of priority, once.	350	coroutine, regardless of priority. This is useful sometimes to ensure
		351	progress is made.
244		352
245	=item terminate [arg...]	353	=item terminate [arg...]
246		354
247	Terminates the current coroutine with the given status values (see L<cancel>).	355	Terminates the current coroutine with the given status values (see L<cancel>).
		356
		357	=item killall
		358
		359	Kills/terminates/cancels all coroutines except the currently running
		360	one. This is useful after a fork, either in the child or the parent, as
		361	usually only one of them should inherit the running coroutines.
		362
		363	Note that while this will try to free some of the main programs resources,
		364	you cannot free all of them, so if a coroutine that is not the main
		365	program calls this function, there will be some one-time resource leak.
248		366
249	=cut	367	=cut
250		368
251	sub terminate {	369	sub terminate {
252	$current->cancel (@_);	370	$current->cancel (@_);
253	}	371	}
254		372
		373	sub killall {
		374	for (Coro::State::list) {
		375	$_->cancel
		376	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		377	}
		378	}
		379
255	=back	380	=back
256		381
257	# dynamic methods
258
259	=head2 COROUTINE METHODS	382	=head2 COROUTINE METHODS
260		383
261	These are the methods you can call on coroutine objects.	384	These are the methods you can call on coroutine objects (or to create
		385	them).
262		386
263	=over 4	387	=over 4
264		388
265	=item new Coro \&sub [, @args...]	389	=item new Coro \&sub [, @args...]
266		390
267	Create a new coroutine and return it. When the sub returns the coroutine	391	Create a new coroutine and return it. When the sub returns, the coroutine
268	automatically terminates as if C<terminate> with the returned values were	392	automatically terminates as if C<terminate> with the returned values were
269	called. To make the coroutine run you must first put it into the ready queue	393	called. To make the coroutine run you must first put it into the ready
270	by calling the ready method.	394	queue by calling the ready method.
271		395
272	Calling C<exit> in a coroutine will not work correctly, so do not do that.	396	See C<async> and C<Coro::State::new> for additional info about the
		397	coroutine environment.
273		398
274	=cut	399	=cut
275		400
276	sub _run_coro {	401	sub _run_coro {
277	terminate &{+shift};	402	terminate &{+shift};
…		…
283	$class->SUPER::new (\&_run_coro, @_)	408	$class->SUPER::new (\&_run_coro, @_)
284	}	409	}
285		410
286	=item $success = $coroutine->ready	411	=item $success = $coroutine->ready
287		412
288	Put the given coroutine into the ready queue (according to it's priority)	413	Put the given coroutine into the end of its ready queue (there is one
289	and return true. If the coroutine is already in the ready queue, do nothing	414	queue for each priority) and return true. If the coroutine is already in
290	and return false.	415	the ready queue, do nothing and return false.
		416
		417	This ensures that the scheduler will resume this coroutine automatically
		418	once all the coroutines of higher priority and all coroutines of the same
		419	priority that were put into the ready queue earlier have been resumed.
291		420
292	=item $is_ready = $coroutine->is_ready	421	=item $is_ready = $coroutine->is_ready
293		422
294	Return wether the coroutine is currently the ready queue or not,	423	Return whether the coroutine is currently the ready queue or not,
295		424
296	=item $coroutine->cancel (arg...)	425	=item $coroutine->cancel (arg...)
297		426
298	Terminates the given coroutine and makes it return the given arguments as	427	Terminates the given coroutine and makes it return the given arguments as
299	status (default: the empty list).	428	status (default: the empty list). Never returns if the coroutine is the
		429	current coroutine.
300		430
301	=cut	431	=cut
302		432
303	sub cancel {	433	sub cancel {
304	my $self = shift;	434	my $self = shift;
305	$self->{status} = [@_];	435	$self->{_status} = [@_];
		436
		437	if ($current == $self) {
306	push @destroy, $self;	438	push @destroy, $self;
307	$manager->ready;	439	$manager->ready;
308	&schedule if $current == $self;	440	&schedule while 1;
		441	} else {
		442	$self->_cancel;
		443	}
309	}	444	}
310		445
311	=item $coroutine->join	446	=item $coroutine->join
312		447
313	Wait until the coroutine terminates and return any values given to the	448	Wait until the coroutine terminates and return any values given to the
314	C<terminate> or C<cancel> functions. C<join> can be called multiple times	449	C<terminate> or C<cancel> functions. C<join> can be called concurrently
315	from multiple coroutine.	450	from multiple coroutines, and all will be resumed and given the status
		451	return once the C<$coroutine> terminates.
316		452
317	=cut	453	=cut
318		454
319	sub join {	455	sub join {
320	my $self = shift;	456	my $self = shift;
		457
321	unless ($self->{status}) {	458	unless ($self->{_status}) {
322	push @{$self->{join}}, $current;	459	my $current = $current;
323	&schedule;	460
		461	push @{$self->{_on_destroy}}, sub {
		462	$current->ready;
		463	undef $current;
		464	};
		465
		466	&schedule while $current;
324	}	467	}
		468
325	wantarray ? @{$self->{status}} : $self->{status}[0];	469	wantarray ? @{$self->{_status}} : $self->{_status}[0];
326	}	470	}
327		471
328	=item $coroutine->on_destroy (\&cb)	472	=item $coroutine->on_destroy (\&cb)
329		473
330	Registers a callback that is called when this coroutine gets destroyed,	474	Registers a callback that is called when this coroutine gets destroyed,
331	but before it is joined. The callback gets passed the terminate arguments,	475	but before it is joined. The callback gets passed the terminate arguments,
332	if any.	476	if any, and I<must not> die, under any circumstances.
333		477
334	=cut	478	=cut
335		479
336	sub on_destroy {	480	sub on_destroy {
337	my ($self, $cb) = @_;	481	my ($self, $cb) = @_;
338		482
339	push @{ $self->{destroy_cb} }, $cb;	483	push @{ $self->{_on_destroy} }, $cb;
340	}	484	}
341		485
342	=item $oldprio = $coroutine->prio ($newprio)	486	=item $oldprio = $coroutine->prio ($newprio)
343		487
344	Sets (or gets, if the argument is missing) the priority of the	488	Sets (or gets, if the argument is missing) the priority of the
…		…
369	=item $olddesc = $coroutine->desc ($newdesc)	513	=item $olddesc = $coroutine->desc ($newdesc)
370		514
371	Sets (or gets in case the argument is missing) the description for this	515	Sets (or gets in case the argument is missing) the description for this
372	coroutine. This is just a free-form string you can associate with a coroutine.	516	coroutine. This is just a free-form string you can associate with a coroutine.
373		517
		518	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		519	can modify this member directly if you wish.
		520
		521	=item $coroutine->throw ([$scalar])
		522
		523	If C<$throw> is specified and defined, it will be thrown as an exception
		524	inside the coroutine at the next convinient point in time (usually after
		525	it gains control at the next schedule/transfer/cede). Otherwise clears the
		526	exception object.
		527
		528	The exception object will be thrown "as is" with the specified scalar in
		529	C<$@>, i.e. if it is a string, no line number or newline will be appended
		530	(unlike with C<die>).
		531
		532	This can be used as a softer means than C<cancel> to ask a coroutine to
		533	end itself, although there is no guarentee that the exception will lead to
		534	termination, and if the exception isn't caught it might well end the whole
		535	program.
		536
374	=cut	537	=cut
375		538
376	sub desc {	539	sub desc {
377	my $old = $_[0]{desc};	540	my $old = $_[0]{desc};
378	$_[0]{desc} = $_[1] if @_ > 1;	541	$_[0]{desc} = $_[1] if @_ > 1;
…		…
386	=over 4	549	=over 4
387		550
388	=item Coro::nready	551	=item Coro::nready
389		552
390	Returns the number of coroutines that are currently in the ready state,	553	Returns the number of coroutines that are currently in the ready state,
391	i.e. that can be swicthed to. The value C<0> means that the only runnable	554	i.e. that can be switched to by calling C<schedule> directory or
		555	indirectly. The value C<0> means that the only runnable coroutine is the
392	coroutine is the currently running one, so C<cede> would have no effect,	556	currently running one, so C<cede> would have no effect, and C<schedule>
393	and C<schedule> would cause a deadlock unless there is an idle handler	557	would cause a deadlock unless there is an idle handler that wakes up some
394	that wakes up some coroutines.	558	coroutines.
		559
		560	=item my $guard = Coro::guard { ... }
		561
		562	This creates and returns a guard object. Nothing happens until the object
		563	gets destroyed, in which case the codeblock given as argument will be
		564	executed. This is useful to free locks or other resources in case of a
		565	runtime error or when the coroutine gets canceled, as in both cases the
		566	guard block will be executed. The guard object supports only one method,
		567	C<< ->cancel >>, which will keep the codeblock from being executed.
		568
		569	Example: set some flag and clear it again when the coroutine gets canceled
		570	or the function returns:
		571
		572	sub do_something {
		573	my $guard = Coro::guard { $busy = 0 };
		574	$busy = 1;
		575
		576	# do something that requires $busy to be true
		577	}
		578
		579	=cut
		580
		581	sub guard(&) {
		582	bless \(my $cb = $_[0]), "Coro::guard"
		583	}
		584
		585	sub Coro::guard::cancel {
		586	${$_[0]} = sub { };
		587	}
		588
		589	sub Coro::guard::DESTROY {
		590	${$_[0]}->();
		591	}
		592
395		593
396	=item unblock_sub { ... }	594	=item unblock_sub { ... }
397		595
398	This utility function takes a BLOCK or code reference and "unblocks" it,	596	This utility function takes a BLOCK or code reference and "unblocks" it,
399	returning the new coderef. This means that the new coderef will return	597	returning a new coderef. Unblocking means that calling the new coderef
400	immediately without blocking, returning nothing, while the original code	598	will return immediately without blocking, returning nothing, while the
401	ref will be called (with parameters) from within its own coroutine.	599	original code ref will be called (with parameters) from within another
		600	coroutine.
402		601
403	The reason this fucntion exists is that many event libraries (such as the	602	The reason this function exists is that many event libraries (such as the
404	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	603	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
405	of thread-safety). This means you must not block within event callbacks,	604	of thread-safety). This means you must not block within event callbacks,
406	otherwise you might suffer from crashes or worse.	605	otherwise you might suffer from crashes or worse. The only event library
		606	currently known that is safe to use without C<unblock_sub> is L<EV>.
407		607
408	This function allows your callbacks to block by executing them in another	608	This function allows your callbacks to block by executing them in another
409	coroutine where it is safe to block. One example where blocking is handy	609	coroutine where it is safe to block. One example where blocking is handy
410	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	610	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
411	disk.	611	disk, for example.
412		612
413	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	613	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
414	creating event callbacks that want to block.	614	creating event callbacks that want to block.
415		615
416	=cut	616	If your handler does not plan to block (e.g. simply sends a message to
		617	another coroutine, or puts some other coroutine into the ready queue),
		618	there is no reason to use C<unblock_sub>.
417		619
418	our @unblock_pool;	620	Note that you also need to use C<unblock_sub> for any other callbacks that
		621	are indirectly executed by any C-based event loop. For example, when you
		622	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		623	provides callbacks that are the result of some event callback, then you
		624	must not block either, or use C<unblock_sub>.
		625
		626	=cut
		627
419	our @unblock_queue;	628	our @unblock_queue;
420	our $UNBLOCK_POOL_SIZE = 2;
421		629
422	sub unblock_handler_ {	630	# we create a special coro because we want to cede,
423	while () {	631	# to reduce pressure on the coro pool (because most callbacks
424	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	632	# return immediately and can be reused) and because we cannot cede
425	$cb->(@arg);	633	# inside an event callback.
426
427	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
428	push @unblock_pool, $Coro::current;
429	schedule;
430	}
431	}
432
433	our $unblock_scheduler = async {	634	our $unblock_scheduler = new Coro sub {
434	while () {	635	while () {
435	while (my $cb = pop @unblock_queue) {	636	while (my $cb = pop @unblock_queue) {
436	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	637	# this is an inlined copy of async_pool
437	$handler->{arg} = $cb;	638	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		639
		640	$coro->{_invoke} = $cb;
438	$handler->ready;	641	$coro->ready;
439	cede;	642	cede; # for short-lived callbacks, this reduces pressure on the coro pool
440	}	643	}
441		644	schedule; # sleep well
442	schedule;
443	}	645	}
444	};	646	};
		647	$unblock_scheduler->desc ("[unblock_sub scheduler]");
445		648
446	sub unblock_sub(&) {	649	sub unblock_sub(&) {
447	my $cb = shift;	650	my $cb = shift;
448		651
449	sub {	652	sub {
450	push @unblock_queue, [$cb, @_];	653	unshift @unblock_queue, [$cb, @_];
451	$unblock_scheduler->ready;	654	$unblock_scheduler->ready;
452	}	655	}
453	}	656	}
454		657
455	=back	658	=back
…		…
458		661
459	1;	662	1;
460		663
461	=head1 BUGS/LIMITATIONS	664	=head1 BUGS/LIMITATIONS
462		665
463	- you must make very sure that no coro is still active on global
464	destruction. very bad things might happen otherwise (usually segfaults).
465
466	- this module is not thread-safe. You should only ever use this module	666	This module is not perl-pseudo-thread-safe. You should only ever use this
467	from the same thread (this requirement might be losened in the future	667	module from the same thread (this requirement might be removed in the
468	to allow per-thread schedulers, but Coro::State does not yet allow	668	future to allow per-thread schedulers, but Coro::State does not yet allow
469	this).	669	this). I recommend disabling thread support and using processes, as this
		670	is much faster and uses less memory.
470		671
471	=head1 SEE ALSO	672	=head1 SEE ALSO
472		673
		674	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		675
		676	Debugging: L<Coro::Debug>.
		677
473	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	678	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
474		679
475	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	680	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
476		681
477	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	682	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
478		683
479	Embedding: L<Coro:MakeMaker>	684	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		685
		686	XS API: L<Coro::MakeMaker>.
		687
		688	Low level Configuration, Coroutine Environment: L<Coro::State>.
480		689
481	=head1 AUTHOR	690	=head1 AUTHOR
482		691
483	Marc Lehmann <schmorp@schmorp.de>	692	Marc Lehmann <schmorp@schmorp.de>
484	http://home.schmorp.de/	693	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC vs. Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC vs.
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC