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

Comparing Coro/Coro.pm (file contents):
Revision 1.134 by root, Sat Sep 22 14:42:56 2007 UTC vs.
Revision 1.233 by root, Fri Nov 21 06:02:07 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 = '3.7';	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	$idle = sub {
144	require Carp;	136	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	137	Carp::croak ("FATAL: deadlock detected");
146	};	138	};
147		139
148	sub _cancel {
149	my ($self) = @_;
150
151	# free coroutine data and mark as destructed
152	$self->_destroy
153	or return;
154
155	# call all destruction callbacks
156	$_->(@{$self->{status}})
157	for @{(delete $self->{destroy_cb}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	140	# this coroutine is necessary because a coroutine
161	# cannot destroy itself.	141	# cannot destroy itself.
162	my @destroy;	142	our @destroy;
163	my $manager;	143	our $manager;
164		144
165	$manager = new Coro sub {	145	$manager = new Coro sub {
166	while () {	146	while () {
167	(shift @destroy)->_cancel	147	Coro::_cancel shift @destroy
168	while @destroy;	148	while @destroy;
169		149
170	&schedule;	150	&schedule;
171	}	151	}
172	};	152	};
173	$manager->desc ("[coro manager]");	153	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	154	$manager->prio (PRIO_MAX);
175		155
176	# static methods. not really.
177
178	=back	156	=back
179		157
180	=head2 STATIC METHODS	158	=head2 SIMPLE COROUTINE CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		159
184	=over 4	160	=over 4
185		161
186	=item async { ... } [@args...]	162	=item async { ... } [@args...]
187		163
188	Create a new asynchronous coroutine and return it's coroutine object	164	Create a new coroutine and return it's coroutine object (usually
189	(usually unused). When the sub returns the new coroutine is automatically	165	unused). The coroutine will be put into the ready queue, so
		166	it will start running automatically on the next scheduler run.
		167
		168	The first argument is a codeblock/closure that should be executed in the
		169	coroutine. When it returns argument returns the coroutine is automatically
190	terminated.	170	terminated.
		171
		172	The remaining arguments are passed as arguments to the closure.
		173
		174	See the C<Coro::State::new> constructor for info about the coroutine
		175	environment in which coroutines are executed.
191		176
192	Calling C<exit> in a coroutine will do the same as calling exit outside	177	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,	178	the coroutine. Likewise, when the coroutine dies, the program will exit,
194	just as it would in the main program.	179	just as it would in the main program.
195		180
		181	If you do not want that, you can provide a default C<die> handler, or
		182	simply avoid dieing (by use of C<eval>).
		183
196	# create a new coroutine that just prints its arguments	184	Example: Create a new coroutine that just prints its arguments.
		185
197	async {	186	async {
198	print "@_\n";	187	print "@_\n";
199	} 1,2,3,4;	188	} 1,2,3,4;
200		189
201	=cut	190	=cut
…		…
207	}	196	}
208		197
209	=item async_pool { ... } [@args...]	198	=item async_pool { ... } [@args...]
210		199
211	Similar to C<async>, but uses a coroutine pool, so you should not call	200	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	201	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 :).	202	coroutine that might have executed other code already (which can be good
		203	or bad :).
214		204
		205	On the plus side, this function is about twice as fast as creating (and
		206	destroying) a completely new coroutine, so if you need a lot of generic
		207	coroutines in quick successsion, use C<async_pool>, not C<async>.
		208
215	Also, the block is executed in an C<eval> context and a warning will be	209	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	210	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>	211	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,	212	will not work in the expected way, unless you call terminate or cancel,
219	which somehow defeats the purpose of pooling.	213	which somehow defeats the purpose of pooling (but is fine in the
		214	exceptional case).
220		215
221	The priority will be reset to C<0> after each job, otherwise the coroutine	216	The priority will be reset to C<0> after each run, tracing will be
222	will be re-used "as-is".	217	disabled, the description will be reset and the default output filehandle
		218	gets restored, so you can change all these. Otherwise the coroutine will
		219	be re-used "as-is": most notably if you change other per-coroutine global
		220	stuff such as C<$/> you I<must needs> revert that change, which is most
		221	simply done by using local as in: C<< local $/ >>.
223		222
224	The pool size is limited to 8 idle coroutines (this can be adjusted by	223	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	224	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
226	required.	225	coros as required.
227		226
228	If you are concerned about pooled coroutines growing a lot because a	227	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	228	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	229	{ 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	230	addition to that, when the stacks used by a handler grows larger than 32kb
232	(adjustable with $Coro::POOL_RSS) it will also exit.	231	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
233		232
234	=cut	233	=cut
235		234
236	our $POOL_SIZE = 8;	235	our $POOL_SIZE = 8;
237	our $POOL_RSS = 16 * 1024;	236	our $POOL_RSS = 32 * 1024;
238	our @async_pool;	237	our @async_pool;
239		238
240	sub pool_handler {	239	sub pool_handler {
241	my $cb;
242
243	while () {	240	while () {
244	eval {	241	eval {
245	while () {	242	&{&_pool_handler} while 1;
246	$cb = &_pool_1
247	or return;
248
249	&$cb;
250
251	return if &_pool_2;
252
253	undef $cb;
254	schedule;
255	}
256	};	243	};
257		244
258	warn $@ if $@;	245	warn $@ if $@;
259	}	246	}
260	}	247	}
261		248
262	sub async_pool(&@) {	249	=back
263	# this is also inlined into the unlock_scheduler
264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;;
265		250
266	$coro->{_invoke} = [@_];	251	=head2 STATIC METHODS
267	$coro->ready;
268		252
269	$coro	253	Static methods are actually functions that operate on the current coroutine.
270	}	254
		255	=over 4
271		256
272	=item schedule	257	=item schedule
273		258
274	Calls the scheduler. Please note that the current coroutine will not be put	259	Calls the scheduler. The scheduler will find the next coroutine that is
		260	to be run from the ready queue and switches to it. The next coroutine
		261	to be run is simply the one with the highest priority that is longest
		262	in its ready queue. If there is no coroutine ready, it will clal the
		263	C<$Coro::idle> hook.
		264
		265	Please note that the current coroutine will I<not> be put into the ready
275	into the ready queue, so calling this function usually means you will	266	queue, so calling this function usually means you will never be called
276	never be called again unless something else (e.g. an event handler) calls	267	again unless something else (e.g. an event handler) calls C<< ->ready >>,
277	ready.	268	thus waking you up.
278		269
279	The canonical way to wait on external events is this:	270	This makes C<schedule> I<the> generic method to use to block the current
		271	coroutine and wait for events: first you remember the current coroutine in
		272	a variable, then arrange for some callback of yours to call C<< ->ready
		273	>> on that once some event happens, and last you call C<schedule> to put
		274	yourself to sleep. Note that a lot of things can wake your coroutine up,
		275	so you need to check whether the event indeed happened, e.g. by storing the
		276	status in a variable.
280		277
		278	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		279
		280	=item cede
		281
		282	"Cede" to other coroutines. This function puts the current coroutine into
		283	the ready queue and calls C<schedule>, which has the effect of giving
		284	up the current "timeslice" to other coroutines of the same or higher
		285	priority. Once your coroutine gets its turn again it will automatically be
		286	resumed.
		287
		288	This function is often called C<yield> in other languages.
		289
		290	=item Coro::cede_notself
		291
		292	Works like cede, but is not exported by default and will cede to I<any>
		293	coroutine, regardless of priority. This is useful sometimes to ensure
		294	progress is made.
		295
		296	=item terminate [arg...]
		297
		298	Terminates the current coroutine with the given status values (see L<cancel>).
		299
		300	=item killall
		301
		302	Kills/terminates/cancels all coroutines except the currently running
		303	one. This is useful after a fork, either in the child or the parent, as
		304	usually only one of them should inherit the running coroutines.
		305
		306	Note that while this will try to free some of the main programs resources,
		307	you cannot free all of them, so if a coroutine that is not the main
		308	program calls this function, there will be some one-time resource leak.
		309
		310	=cut
		311
		312	sub killall {
		313	for (Coro::State::list) {
		314	$_->cancel
		315	if $_ != $current && UNIVERSAL::isa $_, "Coro";
281	{	316	}
282	# remember current coroutine	317	}
		318
		319	=back
		320
		321	=head2 COROUTINE METHODS
		322
		323	These are the methods you can call on coroutine objects (or to create
		324	them).
		325
		326	=over 4
		327
		328	=item new Coro \&sub [, @args...]
		329
		330	Create a new coroutine and return it. When the sub returns, the coroutine
		331	automatically terminates as if C<terminate> with the returned values were
		332	called. To make the coroutine run you must first put it into the ready
		333	queue by calling the ready method.
		334
		335	See C<async> and C<Coro::State::new> for additional info about the
		336	coroutine environment.
		337
		338	=cut
		339
		340	sub _terminate {
		341	terminate &{+shift};
		342	}
		343
		344	=item $success = $coroutine->ready
		345
		346	Put the given coroutine into the end of its ready queue (there is one
		347	queue for each priority) and return true. If the coroutine is already in
		348	the ready queue, do nothing and return false.
		349
		350	This ensures that the scheduler will resume this coroutine automatically
		351	once all the coroutines of higher priority and all coroutines of the same
		352	priority that were put into the ready queue earlier have been resumed.
		353
		354	=item $is_ready = $coroutine->is_ready
		355
		356	Return whether the coroutine is currently the ready queue or not,
		357
		358	=item $coroutine->cancel (arg...)
		359
		360	Terminates the given coroutine and makes it return the given arguments as
		361	status (default: the empty list). Never returns if the coroutine is the
		362	current coroutine.
		363
		364	=cut
		365
		366	sub cancel {
		367	my $self = shift;
		368
		369	if ($current == $self) {
		370	terminate @_;
		371	} else {
		372	$self->{_status} = [@_];
		373	$self->_cancel;
		374	}
		375	}
		376
		377	=item $coroutine->schedule_to
		378
		379	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		380	of continuing with the next coro from the ready queue, always switch to
		381	the given coroutine object (regardless of priority etc.). The readyness
		382	state of that coroutine isn't changed.
		383
		384	This is an advanced method for special cases - I'd love to hear about any
		385	uses for this one.
		386
		387	=item $coroutine->cede_to
		388
		389	Like C<schedule_to>, but puts the current coroutine into the ready
		390	queue. This has the effect of temporarily switching to the given
		391	coroutine, and continuing some time later.
		392
		393	This is an advanced method for special cases - I'd love to hear about any
		394	uses for this one.
		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
		419	=item $coroutine->join
		420
		421	Wait until the coroutine terminates and return any values given to the
		422	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		423	from multiple coroutines, and all will be resumed and given the status
		424	return once the C<$coroutine> terminates.
		425
		426	=cut
		427
		428	sub join {
		429	my $self = shift;
		430
		431	unless ($self->{_status}) {
283	my $current = $Coro::current;	432	my $current = $current;
284		433
285	# register a hypothetical event handler	434	push @{$self->{_on_destroy}}, sub {
286	on_event_invoke sub {
287	# wake up sleeping coroutine
288	$current->ready;	435	$current->ready;
289	undef $current;	436	undef $current;
290	};	437	};
291		438
292	# call schedule until event occurred.
293	# in case we are woken up for other reasons
294	# (current still defined), loop.
295	Coro::schedule while $current;
296	}
297
298	=item cede
299
300	"Cede" to other coroutines. This function puts the current coroutine into the
301	ready queue and calls C<schedule>, which has the effect of giving up the
302	current "timeslice" to other coroutines of the same or higher priority.
303
304	Returns true if at least one coroutine switch has happened.
305
306	=item Coro::cede_notself
307
308	Works like cede, but is not exported by default and will cede to any
309	coroutine, regardless of priority, once.
310
311	Returns true if at least one coroutine switch has happened.
312
313	=item terminate [arg...]
314
315	Terminates the current coroutine with the given status values (see L<cancel>).
316
317	=cut
318
319	sub terminate {
320	$current->cancel (@_);
321	}
322
323	=back
324
325	# dynamic methods
326
327	=head2 COROUTINE METHODS
328
329	These are the methods you can call on coroutine objects.
330
331	=over 4
332
333	=item new Coro \&sub [, @args...]
334
335	Create a new coroutine and return it. When the sub returns the coroutine
336	automatically terminates as if C<terminate> with the returned values were
337	called. To make the coroutine run you must first put it into the ready queue
338	by calling the ready method.
339
340	See C<async> for additional discussion.
341
342	=cut
343
344	sub _run_coro {
345	terminate &{+shift};
346	}
347
348	sub new {
349	my $class = shift;
350
351	$class->SUPER::new (\&_run_coro, @_)
352	}
353
354	=item $success = $coroutine->ready
355
356	Put the given coroutine into the ready queue (according to it's priority)
357	and return true. If the coroutine is already in the ready queue, do nothing
358	and return false.
359
360	=item $is_ready = $coroutine->is_ready
361
362	Return wether the coroutine is currently the ready queue or not,
363
364	=item $coroutine->cancel (arg...)
365
366	Terminates the given coroutine and makes it return the given arguments as
367	status (default: the empty list). Never returns if the coroutine is the
368	current coroutine.
369
370	=cut
371
372	sub cancel {
373	my $self = shift;
374	$self->{status} = [@_];
375
376	if ($current == $self) {
377	push @destroy, $self;
378	$manager->ready;
379	&schedule while 1;
380	} else {
381	$self->_cancel;
382	}
383	}
384
385	=item $coroutine->join
386
387	Wait until the coroutine terminates and return any values given to the
388	C<terminate> or C<cancel> functions. C<join> can be called multiple times
389	from multiple coroutine.
390
391	=cut
392
393	sub join {
394	my $self = shift;
395
396	unless ($self->{status}) {
397	my $current = $current;
398
399	push @{$self->{destroy_cb}}, sub {
400	$current->ready;
401	undef $current;
402	};
403
404	&schedule while $current;	439	&schedule while $current;
405	}	440	}
406		441
407	wantarray ? @{$self->{status}} : $self->{status}[0];	442	wantarray ? @{$self->{_status}} : $self->{_status}[0];
408	}	443	}
409		444
410	=item $coroutine->on_destroy (\&cb)	445	=item $coroutine->on_destroy (\&cb)
411		446
412	Registers a callback that is called when this coroutine gets destroyed,	447	Registers a callback that is called when this coroutine gets destroyed,
413	but before it is joined. The callback gets passed the terminate arguments,	448	but before it is joined. The callback gets passed the terminate arguments,
414	if any.	449	if any, and I<must not> die, under any circumstances.
415		450
416	=cut	451	=cut
417		452
418	sub on_destroy {	453	sub on_destroy {
419	my ($self, $cb) = @_;	454	my ($self, $cb) = @_;
420		455
421	push @{ $self->{destroy_cb} }, $cb;	456	push @{ $self->{_on_destroy} }, $cb;
422	}	457	}
423		458
424	=item $oldprio = $coroutine->prio ($newprio)	459	=item $oldprio = $coroutine->prio ($newprio)
425		460
426	Sets (or gets, if the argument is missing) the priority of the	461	Sets (or gets, if the argument is missing) the priority of the
…		…
449	higher values mean lower priority, just as in unix).	484	higher values mean lower priority, just as in unix).
450		485
451	=item $olddesc = $coroutine->desc ($newdesc)	486	=item $olddesc = $coroutine->desc ($newdesc)
452		487
453	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
454	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.
		491
		492	This method simply sets the C<< $coroutine->{desc} >> member to the given
		493	string. You can modify this member directly if you wish.
455		494
456	=cut	495	=cut
457		496
458	sub desc {	497	sub desc {
459	my $old = $_[0]{desc};	498	my $old = $_[0]{desc};
460	$_[0]{desc} = $_[1] if @_ > 1;	499	$_[0]{desc} = $_[1] if @_ > 1;
461	$old;	500	$old;
462	}	501	}
463		502
		503	sub transfer {
		504	require Carp;
		505	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		506	}
		507
464	=back	508	=back
465		509
466	=head2 GLOBAL FUNCTIONS	510	=head2 GLOBAL FUNCTIONS
467		511
468	=over 4	512	=over 4
469		513
470	=item Coro::nready	514	=item Coro::nready
471		515
472	Returns the number of coroutines that are currently in the ready state,	516	Returns the number of coroutines that are currently in the ready state,
473	i.e. that can be switched to. The value C<0> means that the only runnable	517	i.e. that can be switched to by calling C<schedule> directory or
		518	indirectly. The value C<0> means that the only runnable coroutine is the
474	coroutine is the currently running one, so C<cede> would have no effect,	519	currently running one, so C<cede> would have no effect, and C<schedule>
475	and C<schedule> would cause a deadlock unless there is an idle handler	520	would cause a deadlock unless there is an idle handler that wakes up some
476	that wakes up some coroutines.	521	coroutines.
477		522
478	=item my $guard = Coro::guard { ... }	523	=item my $guard = Coro::guard { ... }
479		524
480	This creates and returns a guard object. Nothing happens until the object	525	This creates and returns a guard object. Nothing happens until the object
481	gets destroyed, in which case the codeblock given as argument will be	526	gets destroyed, in which case the codeblock given as argument will be
…		…
510		555
511		556
512	=item unblock_sub { ... }	557	=item unblock_sub { ... }
513		558
514	This utility function takes a BLOCK or code reference and "unblocks" it,	559	This utility function takes a BLOCK or code reference and "unblocks" it,
515	returning the new coderef. This means that the new coderef will return	560	returning a new coderef. Unblocking means that calling the new coderef
516	immediately without blocking, returning nothing, while the original code	561	will return immediately without blocking, returning nothing, while the
517	ref will be called (with parameters) from within its own coroutine.	562	original code ref will be called (with parameters) from within another
		563	coroutine.
518		564
519	The reason this function exists is that many event libraries (such as the	565	The reason this function exists is that many event libraries (such as the
520	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	566	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
521	of thread-safety). This means you must not block within event callbacks,	567	of thread-safety). This means you must not block within event callbacks,
522	otherwise you might suffer from crashes or worse.	568	otherwise you might suffer from crashes or worse. The only event library
		569	currently known that is safe to use without C<unblock_sub> is L<EV>.
523		570
524	This function allows your callbacks to block by executing them in another	571	This function allows your callbacks to block by executing them in another
525	coroutine where it is safe to block. One example where blocking is handy	572	coroutine where it is safe to block. One example where blocking is handy
526	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	573	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
527	disk.	574	disk, for example.
528		575
529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	576	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
530	creating event callbacks that want to block.	577	creating event callbacks that want to block.
		578
		579	If your handler does not plan to block (e.g. simply sends a message to
		580	another coroutine, or puts some other coroutine into the ready queue),
		581	there is no reason to use C<unblock_sub>.
		582
		583	Note that you also need to use C<unblock_sub> for any other callbacks that
		584	are indirectly executed by any C-based event loop. For example, when you
		585	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		586	provides callbacks that are the result of some event callback, then you
		587	must not block either, or use C<unblock_sub>.
531		588
532	=cut	589	=cut
533		590
534	our @unblock_queue;	591	our @unblock_queue;
535		592
…		…
538	# return immediately and can be reused) and because we cannot cede	595	# return immediately and can be reused) and because we cannot cede
539	# inside an event callback.	596	# inside an event callback.
540	our $unblock_scheduler = new Coro sub {	597	our $unblock_scheduler = new Coro sub {
541	while () {	598	while () {
542	while (my $cb = pop @unblock_queue) {	599	while (my $cb = pop @unblock_queue) {
543	# this is an inlined copy of async_pool	600	&async_pool (@$cb);
544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
545		601
546	$coro->{_invoke} = $cb;
547	$coro->ready;
548	cede; # for short-lived callbacks, this reduces pressure on the coro pool	602	# for short-lived callbacks, this reduces pressure on the coro pool
		603	# as the chance is very high that the async_poll coro will be back
		604	# in the idle state when cede returns
		605	cede;
549	}	606	}
550	schedule; # sleep well	607	schedule; # sleep well
551	}	608	}
552	};	609	};
553	$unblock_scheduler->desc ("[unblock_sub scheduler]");	610	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
554		611
555	sub unblock_sub(&) {	612	sub unblock_sub(&) {
556	my $cb = shift;	613	my $cb = shift;
557		614
558	sub {	615	sub {
559	unshift @unblock_queue, [$cb, @_];	616	unshift @unblock_queue, [$cb, @_];
560	$unblock_scheduler->ready;	617	$unblock_scheduler->ready;
561	}	618	}
562	}	619	}
563		620
		621	=item $cb = Coro::rouse_cb
		622
		623	Create and return a "rouse callback". That's a code reference that, when
		624	called, will save its arguments and notify the owner coroutine of the
		625	callback.
		626
		627	See the next function.
		628
		629	=item @args = Coro::rouse_wait [$cb]
		630
		631	Wait for the specified rouse callback (or the last one tht was created in
		632	this coroutine).
		633
		634	As soon as the callback is invoked (or when the calback was invoked before
		635	C<rouse_wait>), it will return a copy of the arguments originally passed
		636	to the rouse callback.
		637
		638	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		639
564	=back	640	=back
565		641
566	=cut	642	=cut
567		643
568	1;	644	1;
569		645
		646	=head1 HOW TO WAIT FOR A CALLBACK
		647
		648	It is very common for a coroutine to wait for some callback to be
		649	called. This occurs naturally when you use coroutines in an otherwise
		650	event-based program, or when you use event-based libraries.
		651
		652	These typically register a callback for some event, and call that callback
		653	when the event occured. In a coroutine, however, you typically want to
		654	just wait for the event, simplyifying things.
		655
		656	For example C<< AnyEvent->child >> registers a callback to be called when
		657	a specific child has exited:
		658
		659	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		660
		661	But from withina coroutine, you often just want to write this:
		662
		663	my $status = wait_for_child $pid;
		664
		665	Coro offers two functions specifically designed to make this easy,
		666	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		667
		668	The first function, C<rouse_cb>, generates and returns a callback that,
		669	when invoked, will save it's arguments and notify the coroutine that
		670	created the callback.
		671
		672	The second function, C<rouse_wait>, waits for the callback to be called
		673	(by calling C<schedule> to go to sleep) and returns the arguments
		674	originally passed to the callback.
		675
		676	Using these functions, it becomes easy to write the C<wait_for_child>
		677	function mentioned above:
		678
		679	sub wait_for_child($) {
		680	my ($pid) = @_;
		681
		682	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		683
		684	my ($rpid, $rstatus) = Coro::rouse_wait;
		685	$rstatus
		686	}
		687
		688	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		689	you can roll your own, using C<schedule>:
		690
		691	sub wait_for_child($) {
		692	my ($pid) = @_;
		693
		694	# store the current coroutine in $current,
		695	# and provide result variables for the closure passed to ->child
		696	my $current = $Coro::current;
		697	my ($done, $rstatus);
		698
		699	# pass a closure to ->child
		700	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		701	$rstatus = $_[1]; # remember rstatus
		702	$done = 1; # mark $rstatus as valud
		703	});
		704
		705	# wait until the closure has been called
		706	schedule while !$done;
		707
		708	$rstatus
		709	}
		710
		711
570	=head1 BUGS/LIMITATIONS	712	=head1 BUGS/LIMITATIONS
571		713
572	- you must make very sure that no coro is still active on global	714	=over 4
573	destruction. very bad things might happen otherwise (usually segfaults).
574		715
		716	=item fork with pthread backend
		717
		718	When Coro is compiled using the pthread backend (which isn't recommended
		719	but required on many BSDs as their libcs are completely broken), then
		720	coroutines will not survive a fork. There is no known workaround except to
		721	fix your libc and use a saner backend.
		722
		723	=item perl process emulation ("threads")
		724
575	- this module is not thread-safe. You should only ever use this module	725	This module is not perl-pseudo-thread-safe. You should only ever use this
576	from the same thread (this requirement might be loosened in the future	726	module from the same thread (this requirement might be removed in the
577	to allow per-thread schedulers, but Coro::State does not yet allow	727	future to allow per-thread schedulers, but Coro::State does not yet allow
578	this).	728	this). I recommend disabling thread support and using processes, as having
		729	the windows process emulation enabled under unix roughly halves perl
		730	performance, even when not used.
		731
		732	=item coroutine switching not signal safe
		733
		734	You must not switch to another coroutine from within a signal handler
		735	(only relevant with %SIG - most event libraries provide safe signals).
		736
		737	That means you I<MUST NOT> call any function that might "block" the
		738	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		739	anything that calls those. Everything else, including calling C<ready>,
		740	works.
		741
		742	=back
		743
579		744
580	=head1 SEE ALSO	745	=head1 SEE ALSO
581		746
		747	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		748
		749	Debugging: L<Coro::Debug>.
		750
582	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	751	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
583		752
584	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	753	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
585		754
586	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	755	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
587		756
588	Embedding: L<Coro:MakeMaker>	757	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		758
		759	XS API: L<Coro::MakeMaker>.
		760
		761	Low level Configuration, Coroutine Environment: L<Coro::State>.
589		762
590	=head1 AUTHOR	763	=head1 AUTHOR
591		764
592	Marc Lehmann <schmorp@schmorp.de>	765	Marc Lehmann <schmorp@schmorp.de>
593	http://home.schmorp.de/	766	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.134 by root, Sat Sep 22 14:42:56 2007 UTC vs. Revision 1.233 by root, Fri Nov 21 06:02:07 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.134 by root, Sat Sep 22 14:42:56 2007 UTC vs.
Revision 1.233 by root, Fri Nov 21 06:02:07 2008 UTC