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

Comparing Coro/Coro.pm (file contents):
Revision 1.142 by root, Tue Oct 2 23:16:24 2007 UTC vs.
Revision 1.224 by root, Wed Nov 19 05:52:42 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 used in this module also	33	on SMP machines. The specific flavor of coroutine used in this module
26	guarantees 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
44	use strict;	61	use strict qw(vars subs);
45	no warnings "uninitialized";	62	no warnings "uninitialized";
46		63
47	use Coro::State;	64	use Coro::State;
48		65
49	use base qw(Coro::State Exporter);	66	use base qw(Coro::State Exporter);
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 = '3.8';	72	our $VERSION = 5.0;
56		73
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	77	);
61	our @EXPORT_OK = (@{$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 is now being initialised by Coro::State
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<$Coro::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 essential 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
117		104
118	$main->{desc} = "[main::]";
119
120	# maybe some other module used Coro::Specific before...
121	$main->{_specific} = $current->{_specific}
122	if $current;
123
124	_set_current $main;
125
126	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
127		106
128	=item $idle	107	=item $Coro::idle
129		108
130	A callback that is called whenever the scheduler finds no ready coroutines	109	This variable is mainly useful to integrate Coro into event loops. It is
131	to run. The default implementation prints "FATAL: deadlock detected" and	110	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
132	exits, because the program has no other way to continue.	111	pretty low-level functionality.
		112
		113	This variable stores a callback that is called whenever the scheduler
		114	finds no ready coroutines to run. The default implementation prints
		115	"FATAL: deadlock detected" and exits, because the program has no other way
		116	to continue.
133		117
134	This hook is overwritten by modules such as C<Coro::Timer> and	118	This hook is overwritten by modules such as C<Coro::Timer> and
135	C<Coro::Event> to wait on an external event that hopefully wake up a	119	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
136	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
137		121
		122	Note that the callback I<must not>, under any circumstances, block
		123	the current coroutine. Normally, this is achieved by having an "idle
		124	coroutine" that calls the event loop and then blocks again, and then
		125	readying that coroutine in the idle handler.
		126
		127	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		128	technique.
		129
138	Please note that if your callback recursively invokes perl (e.g. for event	130	Please note that if your callback recursively invokes perl (e.g. for event
139	handlers), then it must be prepared to be called recursively.	131	handlers), then it must be prepared to be called recursively itself.
140		132
141	=cut	133	=cut
142		134
143	$idle = sub {	135	$idle = sub {
144	require Carp;	136	require Carp;
…		…
152	$self->_destroy	144	$self->_destroy
153	or return;	145	or return;
154		146
155	# call all destruction callbacks	147	# call all destruction callbacks
156	$_->(@{$self->{_status}})	148	$_->(@{$self->{_status}})
157	for @{(delete $self->{_on_destroy}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
158	}	150	}
159		151
160	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
161	# cannot destroy itself.	153	# cannot destroy itself.
162	my @destroy;	154	my @destroy;
…		…
168	while @destroy;	160	while @destroy;
169		161
170	&schedule;	162	&schedule;
171	}	163	}
172	};	164	};
173	$manager->desc ("[coro manager]");	165	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
175		167
176	# static methods. not really.
177
178	=back	168	=back
179		169
180	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		171
184	=over 4	172	=over 4
185		173
186	=item async { ... } [@args...]	174	=item async { ... } [@args...]
187		175
188	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
189	(usually unused). When the sub returns the new coroutine is automatically	177	unused). The coroutine will be put into the ready queue, so
		178	it will start running automatically on the next scheduler run.
		179
		180	The first argument is a codeblock/closure that should be executed in the
		181	coroutine. When it returns argument returns the coroutine is automatically
190	terminated.	182	terminated.
		183
		184	The remaining arguments are passed as arguments to the closure.
		185
		186	See the C<Coro::State::new> constructor for info about the coroutine
		187	environment in which coroutines are executed.
191		188
192	Calling C<exit> in a coroutine will do the same as calling exit outside	189	Calling C<exit> in a coroutine will do the same as calling exit outside
193	the coroutine. Likewise, when the coroutine dies, the program will exit,	190	the coroutine. Likewise, when the coroutine dies, the program will exit,
194	just as it would in the main program.	191	just as it would in the main program.
195		192
		193	If you do not want that, you can provide a default C<die> handler, or
		194	simply avoid dieing (by use of C<eval>).
		195
196	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
197	async {	198	async {
198	print "@_\n";	199	print "@_\n";
199	} 1,2,3,4;	200	} 1,2,3,4;
200		201
201	=cut	202	=cut
…		…
207	}	208	}
208		209
209	=item async_pool { ... } [@args...]	210	=item async_pool { ... } [@args...]
210		211
211	Similar to C<async>, but uses a coroutine pool, so you should not call	212	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	terminate or join on it (although you are allowed to), and you get a
213	that might have executed other code already (which can be good or bad :).	214	coroutine that might have executed other code already (which can be good
		215	or bad :).
214		216
		217	On the plus side, this function is faster than creating (and destroying)
		218	a completly new coroutine, so if you need a lot of generic coroutines in
		219	quick successsion, use C<async_pool>, not C<async>.
		220
215	Also, the block is executed in an C<eval> context and a warning will be	221	The code 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	222	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>	223	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,	224	will not work in the expected way, unless you call terminate or cancel,
219	which somehow defeats the purpose of pooling.	225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
220		227
221	The priority will be reset to C<0> after each job, otherwise the coroutine	228	The priority will be reset to C<0> after each run, tracing will be
222	will be re-used "as-is".	229	disabled, the description will be reset and the default output filehandle
		230	gets restored, so you can change all these. Otherwise the coroutine will
		231	be re-used "as-is": most notably if you change other per-coroutine global
		232	stuff such as C<$/> you I<must needs> revert that change, which is most
		233	simply done by using local as in: C<< local $/ >>.
223		234
224	The pool size is limited to 8 idle coroutines (this can be adjusted by	235	The idle pool size is limited to C<8> idle coroutines (this can be
225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	236	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
226	required.	237	coros as required.
227		238
228	If you are concerned about pooled coroutines growing a lot because a	239	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	240	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	241	{ 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	242	addition to that, when the stacks used by a handler grows larger than 16kb
232	(adjustable with $Coro::POOL_RSS) it will also exit.	243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
233		244
234	=cut	245	=cut
235		246
236	our $POOL_SIZE = 8;	247	our $POOL_SIZE = 8;
237	our $POOL_RSS = 16 * 1024;	248	our $POOL_RSS = 16 * 1024;
…		…
248	_pool_2 $cb;	259	_pool_2 $cb;
249	&schedule;	260	&schedule;
250	}	261	}
251	};	262	};
252		263
		264	if ($@) {
253	last if $@ eq "\3terminate\2\n";	265	last if $@ eq "\3async_pool terminate\2\n";
254	warn $@ if $@;	266	warn $@;
		267	}
255	}	268	}
256	}	269	}
257		270
258	sub async_pool(&@) {	271	sub async_pool(&@) {
259	# this is also inlined into the unlock_scheduler	272	# this is also inlined into the unblock_scheduler
260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;	273	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
261		274
262	$coro->{_invoke} = [@_];	275	$coro->{_invoke} = [@_];
263	$coro->ready;	276	$coro->ready;
264		277
265	$coro	278	$coro
266	}	279	}
267		280
		281	=back
		282
		283	=head2 STATIC METHODS
		284
		285	Static methods are actually functions that operate on the current coroutine.
		286
		287	=over 4
		288
268	=item schedule	289	=item schedule
269		290
270	Calls the scheduler. Please note that the current coroutine will not be put	291	Calls the scheduler. The scheduler will find the next coroutine that is
		292	to be run from the ready queue and switches to it. The next coroutine
		293	to be run is simply the one with the highest priority that is longest
		294	in its ready queue. If there is no coroutine ready, it will clal the
		295	C<$Coro::idle> hook.
		296
		297	Please note that the current coroutine will I<not> be put into the ready
271	into the ready queue, so calling this function usually means you will	298	queue, so calling this function usually means you will never be called
272	never be called again unless something else (e.g. an event handler) calls	299	again unless something else (e.g. an event handler) calls C<< ->ready >>,
273	ready.	300	thus waking you up.
274		301
275	The canonical way to wait on external events is this:	302	This makes C<schedule> I<the> generic method to use to block the current
		303	coroutine and wait for events: first you remember the current coroutine in
		304	a variable, then arrange for some callback of yours to call C<< ->ready
		305	>> on that once some event happens, and last you call C<schedule> to put
		306	yourself to sleep. Note that a lot of things can wake your coroutine up,
		307	so you need to check whether the event indeed happened, e.g. by storing the
		308	status in a variable.
276		309
277	{	310	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
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	}
293		311
294	=item cede	312	=item cede
295		313
296	"Cede" to other coroutines. This function puts the current coroutine into the	314	"Cede" to other coroutines. This function puts the current coroutine into
297	ready queue and calls C<schedule>, which has the effect of giving up the	315	the ready queue and calls C<schedule>, which has the effect of giving
298	current "timeslice" to other coroutines of the same or higher priority.	316	up the current "timeslice" to other coroutines of the same or higher
		317	priority. Once your coroutine gets its turn again it will automatically be
		318	resumed.
299		319
300	Returns true if at least one coroutine switch has happened.	320	This function is often called C<yield> in other languages.
301		321
302	=item Coro::cede_notself	322	=item Coro::cede_notself
303		323
304	Works like cede, but is not exported by default and will cede to any	324	Works like cede, but is not exported by default and will cede to I<any>
305	coroutine, regardless of priority, once.	325	coroutine, regardless of priority. This is useful sometimes to ensure
306		326	progress is made.
307	Returns true if at least one coroutine switch has happened.
308		327
309	=item terminate [arg...]	328	=item terminate [arg...]
310		329
311	Terminates the current coroutine with the given status values (see L<cancel>).	330	Terminates the current coroutine with the given status values (see L<cancel>).
312		331
313	=item killall	332	=item killall
314		333
315	Kills/terminates/cancels all coroutines except the currently running	334	Kills/terminates/cancels all coroutines except the currently running
316	one. This is useful after a fork, either in the child or the parent, as	335	one. This is useful after a fork, either in the child or the parent, as
317	usually only one of them should inherit the running coroutines.	336	usually only one of them should inherit the running coroutines.
		337
		338	Note that while this will try to free some of the main programs resources,
		339	you cannot free all of them, so if a coroutine that is not the main
		340	program calls this function, there will be some one-time resource leak.
318		341
319	=cut	342	=cut
320		343
321	sub terminate {	344	sub terminate {
322	$current->cancel (@_);	345	$current->cancel (@_);
…		…
329	}	352	}
330	}	353	}
331		354
332	=back	355	=back
333		356
334	# dynamic methods
335
336	=head2 COROUTINE METHODS	357	=head2 COROUTINE METHODS
337		358
338	These are the methods you can call on coroutine objects.	359	These are the methods you can call on coroutine objects (or to create
		360	them).
339		361
340	=over 4	362	=over 4
341		363
342	=item new Coro \&sub [, @args...]	364	=item new Coro \&sub [, @args...]
343		365
344	Create a new coroutine and return it. When the sub returns the coroutine	366	Create a new coroutine and return it. When the sub returns, the coroutine
345	automatically terminates as if C<terminate> with the returned values were	367	automatically terminates as if C<terminate> with the returned values were
346	called. To make the coroutine run you must first put it into the ready queue	368	called. To make the coroutine run you must first put it into the ready
347	by calling the ready method.	369	queue by calling the ready method.
348		370
349	See C<async> for additional discussion.	371	See C<async> and C<Coro::State::new> for additional info about the
		372	coroutine environment.
350		373
351	=cut	374	=cut
352		375
353	sub _run_coro {	376	sub _run_coro {
354	terminate &{+shift};	377	terminate &{+shift};
…		…
360	$class->SUPER::new (\&_run_coro, @_)	383	$class->SUPER::new (\&_run_coro, @_)
361	}	384	}
362		385
363	=item $success = $coroutine->ready	386	=item $success = $coroutine->ready
364		387
365	Put the given coroutine into the ready queue (according to it's priority)	388	Put the given coroutine into the end of its ready queue (there is one
366	and return true. If the coroutine is already in the ready queue, do nothing	389	queue for each priority) and return true. If the coroutine is already in
367	and return false.	390	the ready queue, do nothing and return false.
		391
		392	This ensures that the scheduler will resume this coroutine automatically
		393	once all the coroutines of higher priority and all coroutines of the same
		394	priority that were put into the ready queue earlier have been resumed.
368		395
369	=item $is_ready = $coroutine->is_ready	396	=item $is_ready = $coroutine->is_ready
370		397
371	Return wether the coroutine is currently the ready queue or not,	398	Return whether the coroutine is currently the ready queue or not,
372		399
373	=item $coroutine->cancel (arg...)	400	=item $coroutine->cancel (arg...)
374		401
375	Terminates the given coroutine and makes it return the given arguments as	402	Terminates the given coroutine and makes it return the given arguments as
376	status (default: the empty list). Never returns if the coroutine is the	403	status (default: the empty list). Never returns if the coroutine is the
…		…
389	} else {	416	} else {
390	$self->_cancel;	417	$self->_cancel;
391	}	418	}
392	}	419	}
393		420
		421	=item $coroutine->throw ([$scalar])
		422
		423	If C<$throw> is specified and defined, it will be thrown as an exception
		424	inside the coroutine at the next convenient point in time. Otherwise
		425	clears the exception object.
		426
		427	Coro will check for the exception each time a schedule-like-function
		428	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		429	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		430	detect this case and return early in case an exception is pending.
		431
		432	The exception object will be thrown "as is" with the specified scalar in
		433	C<$@>, i.e. if it is a string, no line number or newline will be appended
		434	(unlike with C<die>).
		435
		436	This can be used as a softer means than C<cancel> to ask a coroutine to
		437	end itself, although there is no guarantee that the exception will lead to
		438	termination, and if the exception isn't caught it might well end the whole
		439	program.
		440
		441	You might also think of C<throw> as being the moral equivalent of
		442	C<kill>ing a coroutine with a signal (in this case, a scalar).
		443
394	=item $coroutine->join	444	=item $coroutine->join
395		445
396	Wait until the coroutine terminates and return any values given to the	446	Wait until the coroutine terminates and return any values given to the
397	C<terminate> or C<cancel> functions. C<join> can be called multiple times	447	C<terminate> or C<cancel> functions. C<join> can be called concurrently
398	from multiple coroutine.	448	from multiple coroutines, and all will be resumed and given the status
		449	return once the C<$coroutine> terminates.
399		450
400	=cut	451	=cut
401		452
402	sub join {	453	sub join {
403	my $self = shift;	454	my $self = shift;
…		…
418		469
419	=item $coroutine->on_destroy (\&cb)	470	=item $coroutine->on_destroy (\&cb)
420		471
421	Registers a callback that is called when this coroutine gets destroyed,	472	Registers a callback that is called when this coroutine gets destroyed,
422	but before it is joined. The callback gets passed the terminate arguments,	473	but before it is joined. The callback gets passed the terminate arguments,
423	if any.	474	if any, and I<must not> die, under any circumstances.
424		475
425	=cut	476	=cut
426		477
427	sub on_destroy {	478	sub on_destroy {
428	my ($self, $cb) = @_;	479	my ($self, $cb) = @_;
…		…
458	higher values mean lower priority, just as in unix).	509	higher values mean lower priority, just as in unix).
459		510
460	=item $olddesc = $coroutine->desc ($newdesc)	511	=item $olddesc = $coroutine->desc ($newdesc)
461		512
462	Sets (or gets in case the argument is missing) the description for this	513	Sets (or gets in case the argument is missing) the description for this
463	coroutine. This is just a free-form string you can associate with a coroutine.	514	coroutine. This is just a free-form string you can associate with a
		515	coroutine.
464		516
465	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	517	This method simply sets the C<< $coroutine->{desc} >> member to the given
466	can modify this member directly if you wish.	518	string. You can modify this member directly if you wish.
467		519
468	=cut	520	=cut
469		521
470	sub desc {	522	sub desc {
471	my $old = $_[0]{desc};	523	my $old = $_[0]{desc};
…		…
480	=over 4	532	=over 4
481		533
482	=item Coro::nready	534	=item Coro::nready
483		535
484	Returns the number of coroutines that are currently in the ready state,	536	Returns the number of coroutines that are currently in the ready state,
485	i.e. that can be switched to. The value C<0> means that the only runnable	537	i.e. that can be switched to by calling C<schedule> directory or
		538	indirectly. The value C<0> means that the only runnable coroutine is the
486	coroutine is the currently running one, so C<cede> would have no effect,	539	currently running one, so C<cede> would have no effect, and C<schedule>
487	and C<schedule> would cause a deadlock unless there is an idle handler	540	would cause a deadlock unless there is an idle handler that wakes up some
488	that wakes up some coroutines.	541	coroutines.
489		542
490	=item my $guard = Coro::guard { ... }	543	=item my $guard = Coro::guard { ... }
491		544
492	This creates and returns a guard object. Nothing happens until the object	545	This creates and returns a guard object. Nothing happens until the object
493	gets destroyed, in which case the codeblock given as argument will be	546	gets destroyed, in which case the codeblock given as argument will be
…		…
522		575
523		576
524	=item unblock_sub { ... }	577	=item unblock_sub { ... }
525		578
526	This utility function takes a BLOCK or code reference and "unblocks" it,	579	This utility function takes a BLOCK or code reference and "unblocks" it,
527	returning the new coderef. This means that the new coderef will return	580	returning a new coderef. Unblocking means that calling the new coderef
528	immediately without blocking, returning nothing, while the original code	581	will return immediately without blocking, returning nothing, while the
529	ref will be called (with parameters) from within its own coroutine.	582	original code ref will be called (with parameters) from within another
		583	coroutine.
530		584
531	The reason this function exists is that many event libraries (such as the	585	The reason this function exists is that many event libraries (such as the
532	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	586	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
533	of thread-safety). This means you must not block within event callbacks,	587	of thread-safety). This means you must not block within event callbacks,
534	otherwise you might suffer from crashes or worse.	588	otherwise you might suffer from crashes or worse. The only event library
		589	currently known that is safe to use without C<unblock_sub> is L<EV>.
535		590
536	This function allows your callbacks to block by executing them in another	591	This function allows your callbacks to block by executing them in another
537	coroutine where it is safe to block. One example where blocking is handy	592	coroutine where it is safe to block. One example where blocking is handy
538	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	593	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
539	disk.	594	disk, for example.
540		595
541	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	596	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
542	creating event callbacks that want to block.	597	creating event callbacks that want to block.
		598
		599	If your handler does not plan to block (e.g. simply sends a message to
		600	another coroutine, or puts some other coroutine into the ready queue),
		601	there is no reason to use C<unblock_sub>.
		602
		603	Note that you also need to use C<unblock_sub> for any other callbacks that
		604	are indirectly executed by any C-based event loop. For example, when you
		605	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		606	provides callbacks that are the result of some event callback, then you
		607	must not block either, or use C<unblock_sub>.
543		608
544	=cut	609	=cut
545		610
546	our @unblock_queue;	611	our @unblock_queue;
547		612
…		…
560	cede; # for short-lived callbacks, this reduces pressure on the coro pool	625	cede; # for short-lived callbacks, this reduces pressure on the coro pool
561	}	626	}
562	schedule; # sleep well	627	schedule; # sleep well
563	}	628	}
564	};	629	};
565	$unblock_scheduler->desc ("[unblock_sub scheduler]");	630	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
566		631
567	sub unblock_sub(&) {	632	sub unblock_sub(&) {
568	my $cb = shift;	633	my $cb = shift;
569		634
570	sub {	635	sub {
571	unshift @unblock_queue, [$cb, @_];	636	unshift @unblock_queue, [$cb, @_];
572	$unblock_scheduler->ready;	637	$unblock_scheduler->ready;
573	}	638	}
574	}	639	}
575		640
		641	=item $cb = Coro::rouse_cb
		642
		643	Create and return a "rouse callback". That's a code reference that, when
		644	called, will save its arguments and notify the owner coroutine of the
		645	callback.
		646
		647	See the next function.
		648
		649	=item @args = Coro::rouse_wait [$cb]
		650
		651	Wait for the specified rouse callback (or the last one tht was created in
		652	this coroutine).
		653
		654	As soon as the callback is invoked (or when the calback was invoked before
		655	C<rouse_wait>), it will return a copy of the arguments originally passed
		656	to the rouse callback.
		657
		658	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		659
576	=back	660	=back
577		661
578	=cut	662	=cut
579		663
580	1;	664	1;
581		665
		666	=head1 HOW TO WAIT FOR A CALLBACK
		667
		668	It is very common for a coroutine to wait for some callback to be
		669	called. This occurs naturally when you use coroutines in an otherwise
		670	event-based program, or when you use event-based libraries.
		671
		672	These typically register a callback for some event, and call that callback
		673	when the event occured. In a coroutine, however, you typically want to
		674	just wait for the event, simplyifying things.
		675
		676	For example C<< AnyEvent->child >> registers a callback to be called when
		677	a specific child has exited:
		678
		679	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		680
		681	But from withina coroutine, you often just want to write this:
		682
		683	my $status = wait_for_child $pid;
		684
		685	Coro offers two functions specifically designed to make this easy,
		686	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		687
		688	The first function, C<rouse_cb>, generates and returns a callback that,
		689	when invoked, will save it's arguments and notify the coroutine that
		690	created the callback.
		691
		692	The second function, C<rouse_wait>, waits for the callback to be called
		693	(by calling C<schedule> to go to sleep) and returns the arguments
		694	originally passed to the callback.
		695
		696	Using these functions, it becomes easy to write the C<wait_for_child>
		697	function mentioned above:
		698
		699	sub wait_for_child($) {
		700	my ($pid) = @_;
		701
		702	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		703
		704	my ($rpid, $rstatus) = Coro::rouse_wait;
		705	$rstatus
		706	}
		707
		708	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		709	you can roll your own, using C<schedule>:
		710
		711	sub wait_for_child($) {
		712	my ($pid) = @_;
		713
		714	# store the current coroutine in $current,
		715	# and provide result variables for the closure passed to ->child
		716	my $current = $Coro::current;
		717	my ($done, $rstatus);
		718
		719	# pass a closure to ->child
		720	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		721	$rstatus = $_[1]; # remember rstatus
		722	$done = 1; # mark $rstatus as valud
		723	});
		724
		725	# wait until the closure has been called
		726	schedule while !$done;
		727
		728	$rstatus
		729	}
		730
		731
582	=head1 BUGS/LIMITATIONS	732	=head1 BUGS/LIMITATIONS
583		733
584	- you must make very sure that no coro is still active on global	734	=over 4
585	destruction. very bad things might happen otherwise (usually segfaults).
586		735
		736	=item fork with pthread backend
		737
		738	When Coro is compiled using the pthread backend (which isn't recommended
		739	but required on many BSDs as their libcs are completely broken), then
		740	coroutines will not survive a fork. There is no known workaround except to
		741	fix your libc and use a saner backend.
		742
		743	=item perl process emulation ("threads")
		744
587	- this module is not thread-safe. You should only ever use this module	745	This module is not perl-pseudo-thread-safe. You should only ever use this
588	from the same thread (this requirement might be loosened in the future	746	module from the same thread (this requirement might be removed in the
589	to allow per-thread schedulers, but Coro::State does not yet allow	747	future to allow per-thread schedulers, but Coro::State does not yet allow
590	this).	748	this). I recommend disabling thread support and using processes, as having
		749	the windows process emulation enabled under unix roughly halves perl
		750	performance, even when not used.
		751
		752	=item coroutine switching not signal safe
		753
		754	You must not switch to another coroutine from within a signal handler
		755	(only relevant with %SIG - most event libraries provide safe signals).
		756
		757	That means you I<MUST NOT> call any function that might "block" the
		758	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		759	anything that calls those. Everything else, including calling C<ready>,
		760	works.
		761
		762	=back
		763
591		764
592	=head1 SEE ALSO	765	=head1 SEE ALSO
593		766
		767	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		768
		769	Debugging: L<Coro::Debug>.
		770
594	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	771	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
595		772
596	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	773	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
597		774
598	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	775	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
599		776
600	Embedding: L<Coro:MakeMaker>	777	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		778
		779	XS API: L<Coro::MakeMaker>.
		780
		781	Low level Configuration, Coroutine Environment: L<Coro::State>.
601		782
602	=head1 AUTHOR	783	=head1 AUTHOR
603		784
604	Marc Lehmann <schmorp@schmorp.de>	785	Marc Lehmann <schmorp@schmorp.de>
605	http://home.schmorp.de/	786	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents):
Revision 1.142 by root, Tue Oct 2 23:16:24 2007 UTC vs.
Revision 1.224 by root, Wed Nov 19 05:52:42 2008 UTC