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

Comparing Coro/Coro.pm (file contents):
Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC vs.
Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC

…		…
16	cede; # yield to coroutine	16	cede; # yield to coroutine
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
		21	use Coro::Semaphore;
21	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar	31	This module collection manages coroutines. Coroutines are similar to
31	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
32	machines. The specific flavor of coroutine used in this module also	33	on SMP machines. The specific flavor of coroutine used in this module
33	guarantees you that it will not switch between coroutines unless	34	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and	35	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much	36	parallel access are rarely an issue, making coroutine programming much
36	safer than threads programming.	37	safer and easier than threads programming.
37		38
38	(Perl, however, does not natively support real threads but instead does a	39	Unlike a normal perl program, however, coroutines allow you to have
39	very slow and memory-intensive emulation of processes using threads. This	40	multiple running interpreters that share data, which is especially useful
40	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).
41		51
42	In this module, coroutines are defined as "callchain + lexical variables +	52	In this module, coroutines are defined as "callchain + lexical variables +
43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
44	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
45	variables (see L<Coro::State> for more configuration).	55	variables (see L<Coro::State> for more configuration).
46		56
47	=cut	57	=cut
48		58
49	package Coro;	59	package Coro;
50		60
51	use strict;	61	use strict qw(vars subs);
52	no warnings "uninitialized";	62	no warnings "uninitialized";
53		63
54	use Coro::State;	64	use Coro::State;
55		65
56	use base qw(Coro::State Exporter);	66	use base qw(Coro::State Exporter);
57		67
58	our $idle; # idle handler	68	our $idle; # idle handler
59	our $main; # main coroutine	69	our $main; # main coroutine
60	our $current; # current coroutine	70	our $current; # current coroutine
61		71
62	our $VERSION = '4.51';	72	our $VERSION = 5.0;
63		73
64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
65	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
67	);	77	);
68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
69		79
70	=over 4	80	=over 4
71		81
72	=item $main	82	=item $Coro::main
73		83
74	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
75		88
76	=cut	89	=cut
77		90
78	$main = new Coro;	91	# $main is now being initialised by Coro::State
79		92
80	=item $current (or as function: current)	93	=item $Coro::current
81		94
82	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
83	is C<$main> (of course).	97	C<$Coro::main> (of course).
84		98
85	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
86	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
87	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
88		102
89	=cut	103	=cut
90		104
91	$main->{desc} = "[main::]";
92
93	# maybe some other module used Coro::Specific before...
94	$main->{_specific} = $current->{_specific}
95	if $current;
96
97	_set_current $main;
98
99	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
100		106
101	=item $idle	107	=item $Coro::idle
102		108
103	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
104	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
105	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.
106		117
107	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
108	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
109	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
		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.
110		129
111	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
112	handlers), then it must be prepared to be called recursively itself.	131	handlers), then it must be prepared to be called recursively itself.
113		132
114	=cut	133	=cut
…		…
125	$self->_destroy	144	$self->_destroy
126	or return;	145	or return;
127		146
128	# call all destruction callbacks	147	# call all destruction callbacks
129	$_->(@{$self->{_status}})	148	$_->(@{$self->{_status}})
130	for @{(delete $self->{_on_destroy}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
131	}	150	}
132		151
133	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
134	# cannot destroy itself.	153	# cannot destroy itself.
135	my @destroy;	154	our @destroy;
136	my $manager;	155	our $manager;
137		156
138	$manager = new Coro sub {	157	$manager = new Coro sub {
139	while () {	158	while () {
140	(shift @destroy)->_cancel	159	(shift @destroy)->_cancel
141	while @destroy;	160	while @destroy;
142		161
143	&schedule;	162	&schedule;
144	}	163	}
145	};	164	};
146	$manager->desc ("[coro manager]");	165	$manager->{desc} = "[coro manager]";
147	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
148		167
149	=back	168	=back
150		169
151	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
152
153	Static methods are actually functions that operate on the current coroutine only.
154		171
155	=over 4	172	=over 4
156		173
157	=item async { ... } [@args...]	174	=item async { ... } [@args...]
158		175
159	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
160	(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
161	terminated.	182	terminated.
162		183
		184	The remaining arguments are passed as arguments to the closure.
		185
163	See the C<Coro::State::new> constructor for info about the coroutine	186	See the C<Coro::State::new> constructor for info about the coroutine
164	environment in which coroutines run.	187	environment in which coroutines are executed.
165		188
166	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
167	the coroutine. Likewise, when the coroutine dies, the program will exit,	190	the coroutine. Likewise, when the coroutine dies, the program will exit,
168	just as it would in the main program.	191	just as it would in the main program.
169		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
170	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
171	async {	198	async {
172	print "@_\n";	199	print "@_\n";
173	} 1,2,3,4;	200	} 1,2,3,4;
174		201
175	=cut	202	=cut
…		…
181	}	208	}
182		209
183	=item async_pool { ... } [@args...]	210	=item async_pool { ... } [@args...]
184		211
185	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
186	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
187	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 :).
188		216
		217	On the plus side, this function is about twice as fast as creating (and
		218	destroying) a completely new coroutine, so if you need a lot of generic
		219	coroutines in quick successsion, use C<async_pool>, not C<async>.
		220
189	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
190	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
191	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>
192	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,
193	which somehow defeats the purpose of pooling.	225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
194		227
195	The priority will be reset to C<0> after each job, tracing will be	228	The priority will be reset to C<0> after each run, tracing will be
196	disabled, the description will be reset and the default output filehandle	229	disabled, the description will be reset and the default output filehandle
197	gets restored, so you can change alkl these. Otherwise the coroutine will	230	gets restored, so you can change all these. Otherwise the coroutine will
198	be re-used "as-is": most notably if you change other per-coroutine global	231	be re-used "as-is": most notably if you change other per-coroutine global
199	stuff such as C<$/> you need to revert that change, which is most simply	232	stuff such as C<$/> you I<must needs> revert that change, which is most
200	done by using local as in C< local $/ >.	233	simply done by using local as in: C<< local $/ >>.
201		234
202	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
203	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
204	required.	237	coros as required.
205		238
206	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
207	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
208	{ 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
209	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
210	(adjustable with $Coro::POOL_RSS) it will also exit.	243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
211		244
212	=cut	245	=cut
213		246
214	our $POOL_SIZE = 8;	247	our $POOL_SIZE = 8;
215	our $POOL_RSS = 16 * 1024;	248	our $POOL_RSS = 16 * 1024;
216	our @async_pool;	249	our @async_pool;
217		250
218	sub pool_handler {	251	sub pool_handler {
219	my $cb;
220
221	while () {	252	while () {
222	eval {	253	eval {
223	while () {	254	&{&_pool_handler} while 1;
224	_pool_1 $cb;
225	&$cb;
226	_pool_2 $cb;
227	&schedule;
228	}
229	};	255	};
230		256
231	last if $@ eq "\3async_pool terminate\2\n";
232	warn $@ if $@;	257	warn $@ if $@;
233	}	258	}
234	}	259	}
235		260
236	sub async_pool(&@) {	261	=back
237	# this is also inlined into the unlock_scheduler
238	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
239		262
240	$coro->{_invoke} = [@_];	263	=head2 STATIC METHODS
241	$coro->ready;
242		264
243	$coro	265	Static methods are actually functions that operate on the current coroutine.
244	}	266
		267	=over 4
245		268
246	=item schedule	269	=item schedule
247		270
248	Calls the scheduler. Please note that the current coroutine will not be put	271	Calls the scheduler. The scheduler will find the next coroutine that is
		272	to be run from the ready queue and switches to it. The next coroutine
		273	to be run is simply the one with the highest priority that is longest
		274	in its ready queue. If there is no coroutine ready, it will clal the
		275	C<$Coro::idle> hook.
		276
		277	Please note that the current coroutine will I<not> be put into the ready
249	into the ready queue, so calling this function usually means you will	278	queue, so calling this function usually means you will never be called
250	never be called again unless something else (e.g. an event handler) calls	279	again unless something else (e.g. an event handler) calls C<< ->ready >>,
251	ready.	280	thus waking you up.
252		281
253	The canonical way to wait on external events is this:	282	This makes C<schedule> I<the> generic method to use to block the current
		283	coroutine and wait for events: first you remember the current coroutine in
		284	a variable, then arrange for some callback of yours to call C<< ->ready
		285	>> on that once some event happens, and last you call C<schedule> to put
		286	yourself to sleep. Note that a lot of things can wake your coroutine up,
		287	so you need to check whether the event indeed happened, e.g. by storing the
		288	status in a variable.
254		289
255	{	290	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
256	# remember current coroutine
257	my $current = $Coro::current;
258
259	# register a hypothetical event handler
260	on_event_invoke sub {
261	# wake up sleeping coroutine
262	$current->ready;
263	undef $current;
264	};
265
266	# call schedule until event occurred.
267	# in case we are woken up for other reasons
268	# (current still defined), loop.
269	Coro::schedule while $current;
270	}
271		291
272	=item cede	292	=item cede
273		293
274	"Cede" to other coroutines. This function puts the current coroutine into the	294	"Cede" to other coroutines. This function puts the current coroutine into
275	ready queue and calls C<schedule>, which has the effect of giving up the	295	the ready queue and calls C<schedule>, which has the effect of giving
276	current "timeslice" to other coroutines of the same or higher priority.	296	up the current "timeslice" to other coroutines of the same or higher
		297	priority. Once your coroutine gets its turn again it will automatically be
		298	resumed.
		299
		300	This function is often called C<yield> in other languages.
277		301
278	=item Coro::cede_notself	302	=item Coro::cede_notself
279		303
280	Works like cede, but is not exported by default and will cede to any	304	Works like cede, but is not exported by default and will cede to I<any>
281	coroutine, regardless of priority, once.	305	coroutine, regardless of priority. This is useful sometimes to ensure
		306	progress is made.
282		307
283	=item terminate [arg...]	308	=item terminate [arg...]
284		309
285	Terminates the current coroutine with the given status values (see L<cancel>).	310	Terminates the current coroutine with the given status values (see L<cancel>).
286		311
…		…
288		313
289	Kills/terminates/cancels all coroutines except the currently running	314	Kills/terminates/cancels all coroutines except the currently running
290	one. This is useful after a fork, either in the child or the parent, as	315	one. This is useful after a fork, either in the child or the parent, as
291	usually only one of them should inherit the running coroutines.	316	usually only one of them should inherit the running coroutines.
292		317
		318	Note that while this will try to free some of the main programs resources,
		319	you cannot free all of them, so if a coroutine that is not the main
		320	program calls this function, there will be some one-time resource leak.
		321
293	=cut	322	=cut
294		323
295	sub terminate {	324	sub terminate {
296	$current->cancel (@_);	325	$current->{_status} = [@_];
		326	push @destroy, $current;
		327	$manager->ready;
		328	do { &schedule } while 1;
297	}	329	}
298		330
299	sub killall {	331	sub killall {
300	for (Coro::State::list) {	332	for (Coro::State::list) {
301	$_->cancel	333	$_->cancel
…		…
305		337
306	=back	338	=back
307		339
308	=head2 COROUTINE METHODS	340	=head2 COROUTINE METHODS
309		341
310	These are the methods you can call on coroutine objects.	342	These are the methods you can call on coroutine objects (or to create
		343	them).
311		344
312	=over 4	345	=over 4
313		346
314	=item new Coro \&sub [, @args...]	347	=item new Coro \&sub [, @args...]
315		348
316	Create a new coroutine and return it. When the sub returns the coroutine	349	Create a new coroutine and return it. When the sub returns, the coroutine
317	automatically terminates as if C<terminate> with the returned values were	350	automatically terminates as if C<terminate> with the returned values were
318	called. To make the coroutine run you must first put it into the ready queue	351	called. To make the coroutine run you must first put it into the ready
319	by calling the ready method.	352	queue by calling the ready method.
320		353
321	See C<async> and C<Coro::State::new> for additional info about the	354	See C<async> and C<Coro::State::new> for additional info about the
322	coroutine environment.	355	coroutine environment.
323		356
324	=cut	357	=cut
325		358
326	sub _run_coro {	359	sub _terminate {
327	terminate &{+shift};	360	terminate &{+shift};
328	}	361	}
329		362
330	sub new {
331	my $class = shift;
332
333	$class->SUPER::new (\&_run_coro, @_)
334	}
335
336	=item $success = $coroutine->ready	363	=item $success = $coroutine->ready
337		364
338	Put the given coroutine into the ready queue (according to it's priority)	365	Put the given coroutine into the end of its ready queue (there is one
339	and return true. If the coroutine is already in the ready queue, do nothing	366	queue for each priority) and return true. If the coroutine is already in
340	and return false.	367	the ready queue, do nothing and return false.
		368
		369	This ensures that the scheduler will resume this coroutine automatically
		370	once all the coroutines of higher priority and all coroutines of the same
		371	priority that were put into the ready queue earlier have been resumed.
341		372
342	=item $is_ready = $coroutine->is_ready	373	=item $is_ready = $coroutine->is_ready
343		374
344	Return wether the coroutine is currently the ready queue or not,	375	Return whether the coroutine is currently the ready queue or not,
345		376
346	=item $coroutine->cancel (arg...)	377	=item $coroutine->cancel (arg...)
347		378
348	Terminates the given coroutine and makes it return the given arguments as	379	Terminates the given coroutine and makes it return the given arguments as
349	status (default: the empty list). Never returns if the coroutine is the	380	status (default: the empty list). Never returns if the coroutine is the
…		…
351		382
352	=cut	383	=cut
353		384
354	sub cancel {	385	sub cancel {
355	my $self = shift;	386	my $self = shift;
356	$self->{_status} = [@_];
357		387
358	if ($current == $self) {	388	if ($current == $self) {
359	push @destroy, $self;	389	terminate @_;
360	$manager->ready;
361	&schedule while 1;
362	} else {	390	} else {
		391	$self->{_status} = [@_];
363	$self->_cancel;	392	$self->_cancel;
364	}	393	}
365	}	394	}
		395
		396	=item $coroutine->schedule_to
		397
		398	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		399	of continuing with the next coro from the ready queue, always switch to
		400	the given coroutine object (regardless of priority etc.). The readyness
		401	state of that coroutine isn't changed.
		402
		403	This is an advanced method for special cases - I'd love to hear about any
		404	uses for this one.
		405
		406	=item $coroutine->cede_to
		407
		408	Like C<schedule_to>, but puts the current coroutine into the ready
		409	queue. This has the effect of temporarily switching to the given
		410	coroutine, and continuing some time later.
		411
		412	This is an advanced method for special cases - I'd love to hear about any
		413	uses for this one.
		414
		415	=item $coroutine->throw ([$scalar])
		416
		417	If C<$throw> is specified and defined, it will be thrown as an exception
		418	inside the coroutine at the next convenient point in time. Otherwise
		419	clears the exception object.
		420
		421	Coro will check for the exception each time a schedule-like-function
		422	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		423	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		424	detect this case and return early in case an exception is pending.
		425
		426	The exception object will be thrown "as is" with the specified scalar in
		427	C<$@>, i.e. if it is a string, no line number or newline will be appended
		428	(unlike with C<die>).
		429
		430	This can be used as a softer means than C<cancel> to ask a coroutine to
		431	end itself, although there is no guarantee that the exception will lead to
		432	termination, and if the exception isn't caught it might well end the whole
		433	program.
		434
		435	You might also think of C<throw> as being the moral equivalent of
		436	C<kill>ing a coroutine with a signal (in this case, a scalar).
366		437
367	=item $coroutine->join	438	=item $coroutine->join
368		439
369	Wait until the coroutine terminates and return any values given to the	440	Wait until the coroutine terminates and return any values given to the
370	C<terminate> or C<cancel> functions. C<join> can be called concurrently	441	C<terminate> or C<cancel> functions. C<join> can be called concurrently
371	from multiple coroutines.	442	from multiple coroutines, and all will be resumed and given the status
		443	return once the C<$coroutine> terminates.
372		444
373	=cut	445	=cut
374		446
375	sub join {	447	sub join {
376	my $self = shift;	448	my $self = shift;
…		…
391		463
392	=item $coroutine->on_destroy (\&cb)	464	=item $coroutine->on_destroy (\&cb)
393		465
394	Registers a callback that is called when this coroutine gets destroyed,	466	Registers a callback that is called when this coroutine gets destroyed,
395	but before it is joined. The callback gets passed the terminate arguments,	467	but before it is joined. The callback gets passed the terminate arguments,
396	if any.	468	if any, and I<must not> die, under any circumstances.
397		469
398	=cut	470	=cut
399		471
400	sub on_destroy {	472	sub on_destroy {
401	my ($self, $cb) = @_;	473	my ($self, $cb) = @_;
…		…
431	higher values mean lower priority, just as in unix).	503	higher values mean lower priority, just as in unix).
432		504
433	=item $olddesc = $coroutine->desc ($newdesc)	505	=item $olddesc = $coroutine->desc ($newdesc)
434		506
435	Sets (or gets in case the argument is missing) the description for this	507	Sets (or gets in case the argument is missing) the description for this
436	coroutine. This is just a free-form string you can associate with a coroutine.	508	coroutine. This is just a free-form string you can associate with a
		509	coroutine.
437		510
438	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	511	This method simply sets the C<< $coroutine->{desc} >> member to the given
439	can modify this member directly if you wish.	512	string. You can modify this member directly if you wish.
440
441	=item $coroutine->throw ([$scalar])
442
443	If C<$throw> is specified and defined, it will be thrown as an exception
444	inside the coroutine at the next convinient point in time (usually after
445	it gains control at the next schedule/transfer/cede). Otherwise clears the
446	exception object.
447
448	The exception object will be thrown "as is" with the specified scalar in
449	C<$@>, i.e. if it is a string, no line number or newline will be appended
450	(unlike with C<die>).
451
452	This can be used as a softer means than C<cancel> to ask a coroutine to
453	end itself, although there is no guarentee that the exception will lead to
454	termination, and if the exception isn't caught it might well end the whole
455	program.
456		513
457	=cut	514	=cut
458		515
459	sub desc {	516	sub desc {
460	my $old = $_[0]{desc};	517	my $old = $_[0]{desc};
…		…
469	=over 4	526	=over 4
470		527
471	=item Coro::nready	528	=item Coro::nready
472		529
473	Returns the number of coroutines that are currently in the ready state,	530	Returns the number of coroutines that are currently in the ready state,
474	i.e. that can be switched to. The value C<0> means that the only runnable	531	i.e. that can be switched to by calling C<schedule> directory or
		532	indirectly. The value C<0> means that the only runnable coroutine is the
475	coroutine is the currently running one, so C<cede> would have no effect,	533	currently running one, so C<cede> would have no effect, and C<schedule>
476	and C<schedule> would cause a deadlock unless there is an idle handler	534	would cause a deadlock unless there is an idle handler that wakes up some
477	that wakes up some coroutines.	535	coroutines.
478		536
479	=item my $guard = Coro::guard { ... }	537	=item my $guard = Coro::guard { ... }
480		538
481	This creates and returns a guard object. Nothing happens until the object	539	This creates and returns a guard object. Nothing happens until the object
482	gets destroyed, in which case the codeblock given as argument will be	540	gets destroyed, in which case the codeblock given as argument will be
…		…
511		569
512		570
513	=item unblock_sub { ... }	571	=item unblock_sub { ... }
514		572
515	This utility function takes a BLOCK or code reference and "unblocks" it,	573	This utility function takes a BLOCK or code reference and "unblocks" it,
516	returning the new coderef. This means that the new coderef will return	574	returning a new coderef. Unblocking means that calling the new coderef
517	immediately without blocking, returning nothing, while the original code	575	will return immediately without blocking, returning nothing, while the
518	ref will be called (with parameters) from within its own coroutine.	576	original code ref will be called (with parameters) from within another
		577	coroutine.
519		578
520	The reason this function exists is that many event libraries (such as the	579	The reason this function exists is that many event libraries (such as the
521	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	580	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
522	of thread-safety). This means you must not block within event callbacks,	581	of thread-safety). This means you must not block within event callbacks,
523	otherwise you might suffer from crashes or worse.	582	otherwise you might suffer from crashes or worse. The only event library
		583	currently known that is safe to use without C<unblock_sub> is L<EV>.
524		584
525	This function allows your callbacks to block by executing them in another	585	This function allows your callbacks to block by executing them in another
526	coroutine where it is safe to block. One example where blocking is handy	586	coroutine where it is safe to block. One example where blocking is handy
527	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	587	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
528	disk.	588	disk, for example.
529		589
530	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	590	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
531	creating event callbacks that want to block.	591	creating event callbacks that want to block.
		592
		593	If your handler does not plan to block (e.g. simply sends a message to
		594	another coroutine, or puts some other coroutine into the ready queue),
		595	there is no reason to use C<unblock_sub>.
		596
		597	Note that you also need to use C<unblock_sub> for any other callbacks that
		598	are indirectly executed by any C-based event loop. For example, when you
		599	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		600	provides callbacks that are the result of some event callback, then you
		601	must not block either, or use C<unblock_sub>.
532		602
533	=cut	603	=cut
534		604
535	our @unblock_queue;	605	our @unblock_queue;
536		606
…		…
539	# return immediately and can be reused) and because we cannot cede	609	# return immediately and can be reused) and because we cannot cede
540	# inside an event callback.	610	# inside an event callback.
541	our $unblock_scheduler = new Coro sub {	611	our $unblock_scheduler = new Coro sub {
542	while () {	612	while () {
543	while (my $cb = pop @unblock_queue) {	613	while (my $cb = pop @unblock_queue) {
544	# this is an inlined copy of async_pool	614	&async_pool (@$cb);
545	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
546		615
547	$coro->{_invoke} = $cb;
548	$coro->ready;
549	cede; # for short-lived callbacks, this reduces pressure on the coro pool	616	# for short-lived callbacks, this reduces pressure on the coro pool
		617	# as the chance is very high that the async_poll coro will be back
		618	# in the idle state when cede returns
		619	cede;
550	}	620	}
551	schedule; # sleep well	621	schedule; # sleep well
552	}	622	}
553	};	623	};
554	$unblock_scheduler->desc ("[unblock_sub scheduler]");	624	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
555		625
556	sub unblock_sub(&) {	626	sub unblock_sub(&) {
557	my $cb = shift;	627	my $cb = shift;
558		628
559	sub {	629	sub {
560	unshift @unblock_queue, [$cb, @_];	630	unshift @unblock_queue, [$cb, @_];
561	$unblock_scheduler->ready;	631	$unblock_scheduler->ready;
562	}	632	}
563	}	633	}
564		634
		635	=item $cb = Coro::rouse_cb
		636
		637	Create and return a "rouse callback". That's a code reference that, when
		638	called, will save its arguments and notify the owner coroutine of the
		639	callback.
		640
		641	See the next function.
		642
		643	=item @args = Coro::rouse_wait [$cb]
		644
		645	Wait for the specified rouse callback (or the last one tht was created in
		646	this coroutine).
		647
		648	As soon as the callback is invoked (or when the calback was invoked before
		649	C<rouse_wait>), it will return a copy of the arguments originally passed
		650	to the rouse callback.
		651
		652	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		653
565	=back	654	=back
566		655
567	=cut	656	=cut
568		657
569	1;	658	1;
570		659
		660	=head1 HOW TO WAIT FOR A CALLBACK
		661
		662	It is very common for a coroutine to wait for some callback to be
		663	called. This occurs naturally when you use coroutines in an otherwise
		664	event-based program, or when you use event-based libraries.
		665
		666	These typically register a callback for some event, and call that callback
		667	when the event occured. In a coroutine, however, you typically want to
		668	just wait for the event, simplyifying things.
		669
		670	For example C<< AnyEvent->child >> registers a callback to be called when
		671	a specific child has exited:
		672
		673	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		674
		675	But from withina coroutine, you often just want to write this:
		676
		677	my $status = wait_for_child $pid;
		678
		679	Coro offers two functions specifically designed to make this easy,
		680	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		681
		682	The first function, C<rouse_cb>, generates and returns a callback that,
		683	when invoked, will save it's arguments and notify the coroutine that
		684	created the callback.
		685
		686	The second function, C<rouse_wait>, waits for the callback to be called
		687	(by calling C<schedule> to go to sleep) and returns the arguments
		688	originally passed to the callback.
		689
		690	Using these functions, it becomes easy to write the C<wait_for_child>
		691	function mentioned above:
		692
		693	sub wait_for_child($) {
		694	my ($pid) = @_;
		695
		696	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		697
		698	my ($rpid, $rstatus) = Coro::rouse_wait;
		699	$rstatus
		700	}
		701
		702	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		703	you can roll your own, using C<schedule>:
		704
		705	sub wait_for_child($) {
		706	my ($pid) = @_;
		707
		708	# store the current coroutine in $current,
		709	# and provide result variables for the closure passed to ->child
		710	my $current = $Coro::current;
		711	my ($done, $rstatus);
		712
		713	# pass a closure to ->child
		714	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		715	$rstatus = $_[1]; # remember rstatus
		716	$done = 1; # mark $rstatus as valud
		717	});
		718
		719	# wait until the closure has been called
		720	schedule while !$done;
		721
		722	$rstatus
		723	}
		724
		725
571	=head1 BUGS/LIMITATIONS	726	=head1 BUGS/LIMITATIONS
572		727
573	- you must make very sure that no coro is still active on global	728	=over 4
574	destruction. very bad things might happen otherwise (usually segfaults).
575		729
		730	=item fork with pthread backend
		731
		732	When Coro is compiled using the pthread backend (which isn't recommended
		733	but required on many BSDs as their libcs are completely broken), then
		734	coroutines will not survive a fork. There is no known workaround except to
		735	fix your libc and use a saner backend.
		736
		737	=item perl process emulation ("threads")
		738
576	- this module is not thread-safe. You should only ever use this module	739	This module is not perl-pseudo-thread-safe. You should only ever use this
577	from the same thread (this requirement might be loosened in the future	740	module from the same thread (this requirement might be removed in the
578	to allow per-thread schedulers, but Coro::State does not yet allow	741	future to allow per-thread schedulers, but Coro::State does not yet allow
579	this).	742	this). I recommend disabling thread support and using processes, as having
		743	the windows process emulation enabled under unix roughly halves perl
		744	performance, even when not used.
		745
		746	=item coroutine switching not signal safe
		747
		748	You must not switch to another coroutine from within a signal handler
		749	(only relevant with %SIG - most event libraries provide safe signals).
		750
		751	That means you I<MUST NOT> call any function that might "block" the
		752	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		753	anything that calls those. Everything else, including calling C<ready>,
		754	works.
		755
		756	=back
		757
580		758
581	=head1 SEE ALSO	759	=head1 SEE ALSO
582		760
583	Lower level Configuration, Coroutine Environment: L<Coro::State>.	761	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
584		762
585	Debugging: L<Coro::Debug>.	763	Debugging: L<Coro::Debug>.
586		764
587	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	765	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
588		766
589	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	767	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
590		768
591	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	769	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
592		770
593	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	771	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
594		772
595	Embedding: L<Coro::MakeMaker>.	773	XS API: L<Coro::MakeMaker>.
		774
		775	Low level Configuration, Coroutine Environment: L<Coro::State>.
596		776
597	=head1 AUTHOR	777	=head1 AUTHOR
598		778
599	Marc Lehmann <schmorp@schmorp.de>	779	Marc Lehmann <schmorp@schmorp.de>
600	http://home.schmorp.de/	780	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC vs. Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC vs.
Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC