[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 1.227 by root, Thu Nov 20 03:10:30 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	our @destroy;
163	my $manager;	155	our $manager;
164		156
165	$manager = new Coro sub {	157	$manager = new Coro sub {
166	while () {	158	while () {
167	(shift @destroy)->_cancel	159	(shift @destroy)->_cancel
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;
238	our @async_pool;	249	our @async_pool;
239		250
240	sub pool_handler {	251	sub pool_handler {
241	my $cb;
242
243	while () {	252	while () {
244	eval {	253	eval {
245	while () {	254	&{&_pool_handler} while 1;
246	_pool_1 $cb;
247	&$cb;
248	_pool_2 $cb;
249	&schedule;
250	}
251	};	255	};
252		256
253	last if $@ eq "\3terminate\2\n";
254	warn $@ if $@;	257	warn $@ if $@;
255	}	258	}
256	}	259	}
257		260
258	sub async_pool(&@) {	261	=back
259	# this is also inlined into the unlock_scheduler
260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
261		262
262	$coro->{_invoke} = [@_];	263	=head2 STATIC METHODS
263	$coro->ready;
264		264
265	$coro	265	Static methods are actually functions that operate on the current coroutine.
266	}	266
		267	=over 4
267		268
268	=item schedule	269	=item schedule
269		270
270	Calls the scheduler. Please note that the current coroutine will not be put	271	Calls the scheduler. The scheduler will find the next coroutine that is
		272	to be run from the ready queue and switches to it. The next coroutine
		273	to be run is simply the one with the highest priority that is longest
		274	in its ready queue. If there is no coroutine ready, it will clal the
		275	C<$Coro::idle> hook.
		276
		277	Please note that the current coroutine will I<not> be put into the ready
271	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
272	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 >>,
273	ready.	280	thus waking you up.
274		281
275	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.
276		289
277	{	290	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		291
294	=item cede	292	=item cede
295		293
296	"Cede" to other coroutines. This function puts the current coroutine into the	294	"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	295	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.	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		299
300	Returns true if at least one coroutine switch has happened.	300	This function is often called C<yield> in other languages.
301		301
302	=item Coro::cede_notself	302	=item Coro::cede_notself
303		303
304	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>
305	coroutine, regardless of priority, once.	305	coroutine, regardless of priority. This is useful sometimes to ensure
306		306	progress is made.
307	Returns true if at least one coroutine switch has happened.
308		307
309	=item terminate [arg...]	308	=item terminate [arg...]
310		309
311	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>).
312		311
…		…
314		313
315	Kills/terminates/cancels all coroutines except the currently running	314	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	315	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.	316	usually only one of them should inherit the running coroutines.
318		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
319	=cut	322	=cut
320		323
321	sub terminate {	324	sub terminate {
322	$current->cancel (@_);	325	$current->{_status} = [@_];
		326	push @destroy, $current;
		327	$manager->ready;
		328	do { &schedule } while 1;
323	}	329	}
324		330
325	sub killall {	331	sub killall {
326	for (Coro::State::list) {	332	for (Coro::State::list) {
327	$_->cancel	333	$_->cancel
…		…
329	}	335	}
330	}	336	}
331		337
332	=back	338	=back
333		339
334	# dynamic methods
335
336	=head2 COROUTINE METHODS	340	=head2 COROUTINE METHODS
337		341
338	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).
339		344
340	=over 4	345	=over 4
341		346
342	=item new Coro \&sub [, @args...]	347	=item new Coro \&sub [, @args...]
343		348
344	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
345	automatically terminates as if C<terminate> with the returned values were	350	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	351	called. To make the coroutine run you must first put it into the ready
347	by calling the ready method.	352	queue by calling the ready method.
348		353
349	See C<async> for additional discussion.	354	See C<async> and C<Coro::State::new> for additional info about the
		355	coroutine environment.
350		356
351	=cut	357	=cut
352		358
353	sub _run_coro {	359	sub _terminate {
354	terminate &{+shift};	360	terminate &{+shift};
355	}	361	}
356		362
357	sub new {
358	my $class = shift;
359
360	$class->SUPER::new (\&_run_coro, @_)
361	}
362
363	=item $success = $coroutine->ready	363	=item $success = $coroutine->ready
364		364
365	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
366	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
367	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.
368		372
369	=item $is_ready = $coroutine->is_ready	373	=item $is_ready = $coroutine->is_ready
370		374
371	Return wether the coroutine is currently the ready queue or not,	375	Return whether the coroutine is currently the ready queue or not,
372		376
373	=item $coroutine->cancel (arg...)	377	=item $coroutine->cancel (arg...)
374		378
375	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
376	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
…		…
378		382
379	=cut	383	=cut
380		384
381	sub cancel {	385	sub cancel {
382	my $self = shift;	386	my $self = shift;
383	$self->{_status} = [@_];
384		387
385	if ($current == $self) {	388	if ($current == $self) {
386	push @destroy, $self;	389	terminate @_;
387	$manager->ready;
388	&schedule while 1;
389	} else {	390	} else {
		391	$self->{_status} = [@_];
390	$self->_cancel;	392	$self->_cancel;
391	}	393	}
392	}	394	}
393		395
		396	=item $coroutine->throw ([$scalar])
		397
		398	If C<$throw> is specified and defined, it will be thrown as an exception
		399	inside the coroutine at the next convenient point in time. Otherwise
		400	clears the exception object.
		401
		402	Coro will check for the exception each time a schedule-like-function
		403	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		404	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		405	detect this case and return early in case an exception is pending.
		406
		407	The exception object will be thrown "as is" with the specified scalar in
		408	C<$@>, i.e. if it is a string, no line number or newline will be appended
		409	(unlike with C<die>).
		410
		411	This can be used as a softer means than C<cancel> to ask a coroutine to
		412	end itself, although there is no guarantee that the exception will lead to
		413	termination, and if the exception isn't caught it might well end the whole
		414	program.
		415
		416	You might also think of C<throw> as being the moral equivalent of
		417	C<kill>ing a coroutine with a signal (in this case, a scalar).
		418
394	=item $coroutine->join	419	=item $coroutine->join
395		420
396	Wait until the coroutine terminates and return any values given to the	421	Wait until the coroutine terminates and return any values given to the
397	C<terminate> or C<cancel> functions. C<join> can be called multiple times	422	C<terminate> or C<cancel> functions. C<join> can be called concurrently
398	from multiple coroutine.	423	from multiple coroutines, and all will be resumed and given the status
		424	return once the C<$coroutine> terminates.
399		425
400	=cut	426	=cut
401		427
402	sub join {	428	sub join {
403	my $self = shift;	429	my $self = shift;
…		…
418		444
419	=item $coroutine->on_destroy (\&cb)	445	=item $coroutine->on_destroy (\&cb)
420		446
421	Registers a callback that is called when this coroutine gets destroyed,	447	Registers a callback that is called when this coroutine gets destroyed,
422	but before it is joined. The callback gets passed the terminate arguments,	448	but before it is joined. The callback gets passed the terminate arguments,
423	if any.	449	if any, and I<must not> die, under any circumstances.
424		450
425	=cut	451	=cut
426		452
427	sub on_destroy {	453	sub on_destroy {
428	my ($self, $cb) = @_;	454	my ($self, $cb) = @_;
…		…
458	higher values mean lower priority, just as in unix).	484	higher values mean lower priority, just as in unix).
459		485
460	=item $olddesc = $coroutine->desc ($newdesc)	486	=item $olddesc = $coroutine->desc ($newdesc)
461		487
462	Sets (or gets in case the argument is missing) the description for this	488	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.	489	coroutine. This is just a free-form string you can associate with a
		490	coroutine.
464		491
465	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	492	This method simply sets the C<< $coroutine->{desc} >> member to the given
466	can modify this member directly if you wish.	493	string. You can modify this member directly if you wish.
467		494
468	=cut	495	=cut
469		496
470	sub desc {	497	sub desc {
471	my $old = $_[0]{desc};	498	my $old = $_[0]{desc};
…		…
480	=over 4	507	=over 4
481		508
482	=item Coro::nready	509	=item Coro::nready
483		510
484	Returns the number of coroutines that are currently in the ready state,	511	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	512	i.e. that can be switched to by calling C<schedule> directory or
		513	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,	514	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	515	would cause a deadlock unless there is an idle handler that wakes up some
488	that wakes up some coroutines.	516	coroutines.
489		517
490	=item my $guard = Coro::guard { ... }	518	=item my $guard = Coro::guard { ... }
491		519
492	This creates and returns a guard object. Nothing happens until the object	520	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	521	gets destroyed, in which case the codeblock given as argument will be
…		…
522		550
523		551
524	=item unblock_sub { ... }	552	=item unblock_sub { ... }
525		553
526	This utility function takes a BLOCK or code reference and "unblocks" it,	554	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	555	returning a new coderef. Unblocking means that calling the new coderef
528	immediately without blocking, returning nothing, while the original code	556	will return immediately without blocking, returning nothing, while the
529	ref will be called (with parameters) from within its own coroutine.	557	original code ref will be called (with parameters) from within another
		558	coroutine.
530		559
531	The reason this function exists is that many event libraries (such as the	560	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	561	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,	562	of thread-safety). This means you must not block within event callbacks,
534	otherwise you might suffer from crashes or worse.	563	otherwise you might suffer from crashes or worse. The only event library
		564	currently known that is safe to use without C<unblock_sub> is L<EV>.
535		565
536	This function allows your callbacks to block by executing them in another	566	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	567	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	568	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
539	disk.	569	disk, for example.
540		570
541	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	571	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
542	creating event callbacks that want to block.	572	creating event callbacks that want to block.
		573
		574	If your handler does not plan to block (e.g. simply sends a message to
		575	another coroutine, or puts some other coroutine into the ready queue),
		576	there is no reason to use C<unblock_sub>.
		577
		578	Note that you also need to use C<unblock_sub> for any other callbacks that
		579	are indirectly executed by any C-based event loop. For example, when you
		580	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		581	provides callbacks that are the result of some event callback, then you
		582	must not block either, or use C<unblock_sub>.
543		583
544	=cut	584	=cut
545		585
546	our @unblock_queue;	586	our @unblock_queue;
547		587
…		…
550	# return immediately and can be reused) and because we cannot cede	590	# return immediately and can be reused) and because we cannot cede
551	# inside an event callback.	591	# inside an event callback.
552	our $unblock_scheduler = new Coro sub {	592	our $unblock_scheduler = new Coro sub {
553	while () {	593	while () {
554	while (my $cb = pop @unblock_queue) {	594	while (my $cb = pop @unblock_queue) {
555	# this is an inlined copy of async_pool	595	&async_pool (@$cb);
556	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
557		596
558	$coro->{_invoke} = $cb;
559	$coro->ready;
560	cede; # for short-lived callbacks, this reduces pressure on the coro pool	597	# for short-lived callbacks, this reduces pressure on the coro pool
		598	# as the chance is very high that the async_poll coro will be back
		599	# in the idle state when cede returns
		600	cede;
561	}	601	}
562	schedule; # sleep well	602	schedule; # sleep well
563	}	603	}
564	};	604	};
565	$unblock_scheduler->desc ("[unblock_sub scheduler]");	605	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
566		606
567	sub unblock_sub(&) {	607	sub unblock_sub(&) {
568	my $cb = shift;	608	my $cb = shift;
569		609
570	sub {	610	sub {
571	unshift @unblock_queue, [$cb, @_];	611	unshift @unblock_queue, [$cb, @_];
572	$unblock_scheduler->ready;	612	$unblock_scheduler->ready;
573	}	613	}
574	}	614	}
575		615
		616	=item $cb = Coro::rouse_cb
		617
		618	Create and return a "rouse callback". That's a code reference that, when
		619	called, will save its arguments and notify the owner coroutine of the
		620	callback.
		621
		622	See the next function.
		623
		624	=item @args = Coro::rouse_wait [$cb]
		625
		626	Wait for the specified rouse callback (or the last one tht was created in
		627	this coroutine).
		628
		629	As soon as the callback is invoked (or when the calback was invoked before
		630	C<rouse_wait>), it will return a copy of the arguments originally passed
		631	to the rouse callback.
		632
		633	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		634
576	=back	635	=back
577		636
578	=cut	637	=cut
579		638
580	1;	639	1;
581		640
		641	=head1 HOW TO WAIT FOR A CALLBACK
		642
		643	It is very common for a coroutine to wait for some callback to be
		644	called. This occurs naturally when you use coroutines in an otherwise
		645	event-based program, or when you use event-based libraries.
		646
		647	These typically register a callback for some event, and call that callback
		648	when the event occured. In a coroutine, however, you typically want to
		649	just wait for the event, simplyifying things.
		650
		651	For example C<< AnyEvent->child >> registers a callback to be called when
		652	a specific child has exited:
		653
		654	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		655
		656	But from withina coroutine, you often just want to write this:
		657
		658	my $status = wait_for_child $pid;
		659
		660	Coro offers two functions specifically designed to make this easy,
		661	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		662
		663	The first function, C<rouse_cb>, generates and returns a callback that,
		664	when invoked, will save it's arguments and notify the coroutine that
		665	created the callback.
		666
		667	The second function, C<rouse_wait>, waits for the callback to be called
		668	(by calling C<schedule> to go to sleep) and returns the arguments
		669	originally passed to the callback.
		670
		671	Using these functions, it becomes easy to write the C<wait_for_child>
		672	function mentioned above:
		673
		674	sub wait_for_child($) {
		675	my ($pid) = @_;
		676
		677	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		678
		679	my ($rpid, $rstatus) = Coro::rouse_wait;
		680	$rstatus
		681	}
		682
		683	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		684	you can roll your own, using C<schedule>:
		685
		686	sub wait_for_child($) {
		687	my ($pid) = @_;
		688
		689	# store the current coroutine in $current,
		690	# and provide result variables for the closure passed to ->child
		691	my $current = $Coro::current;
		692	my ($done, $rstatus);
		693
		694	# pass a closure to ->child
		695	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		696	$rstatus = $_[1]; # remember rstatus
		697	$done = 1; # mark $rstatus as valud
		698	});
		699
		700	# wait until the closure has been called
		701	schedule while !$done;
		702
		703	$rstatus
		704	}
		705
		706
582	=head1 BUGS/LIMITATIONS	707	=head1 BUGS/LIMITATIONS
583		708
584	- you must make very sure that no coro is still active on global	709	=over 4
585	destruction. very bad things might happen otherwise (usually segfaults).
586		710
		711	=item fork with pthread backend
		712
		713	When Coro is compiled using the pthread backend (which isn't recommended
		714	but required on many BSDs as their libcs are completely broken), then
		715	coroutines will not survive a fork. There is no known workaround except to
		716	fix your libc and use a saner backend.
		717
		718	=item perl process emulation ("threads")
		719
587	- this module is not thread-safe. You should only ever use this module	720	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	721	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	722	future to allow per-thread schedulers, but Coro::State does not yet allow
590	this).	723	this). I recommend disabling thread support and using processes, as having
		724	the windows process emulation enabled under unix roughly halves perl
		725	performance, even when not used.
		726
		727	=item coroutine switching not signal safe
		728
		729	You must not switch to another coroutine from within a signal handler
		730	(only relevant with %SIG - most event libraries provide safe signals).
		731
		732	That means you I<MUST NOT> call any function that might "block" the
		733	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		734	anything that calls those. Everything else, including calling C<ready>,
		735	works.
		736
		737	=back
		738
591		739
592	=head1 SEE ALSO	740	=head1 SEE ALSO
593		741
		742	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		743
		744	Debugging: L<Coro::Debug>.
		745
594	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	746	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
595		747
596	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	748	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
597		749
598	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	750	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
599		751
600	Embedding: L<Coro:MakeMaker>	752	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		753
		754	XS API: L<Coro::MakeMaker>.
		755
		756	Low level Configuration, Coroutine Environment: L<Coro::State>.
601		757
602	=head1 AUTHOR	758	=head1 AUTHOR
603		759
604	Marc Lehmann <schmorp@schmorp.de>	760	Marc Lehmann <schmorp@schmorp.de>
605	http://home.schmorp.de/	761	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 1.227 by root, Thu Nov 20 03:10:30 2008 UTC

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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 1.227 by root, Thu Nov 20 03:10:30 2008 UTC