[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 1.233 by root, Fri Nov 21 06:02:07 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
…		…
116	$idle = sub {	135	$idle = sub {
117	require Carp;	136	require Carp;
118	Carp::croak ("FATAL: deadlock detected");	137	Carp::croak ("FATAL: deadlock detected");
119	};	138	};
120		139
121	sub _cancel {
122	my ($self) = @_;
123
124	# free coroutine data and mark as destructed
125	$self->_destroy
126	or return;
127
128	# call all destruction callbacks
129	$_->(@{$self->{_status}})
130	for @{(delete $self->{_on_destroy}) \|\| []};
131	}
132
133	# this coroutine is necessary because a coroutine	140	# this coroutine is necessary because a coroutine
134	# cannot destroy itself.	141	# cannot destroy itself.
135	my @destroy;	142	our @destroy;
136	my $manager;	143	our $manager;
137		144
138	$manager = new Coro sub {	145	$manager = new Coro sub {
139	while () {	146	while () {
140	(shift @destroy)->_cancel	147	Coro::_cancel shift @destroy
141	while @destroy;	148	while @destroy;
142		149
143	&schedule;	150	&schedule;
144	}	151	}
145	};	152	};
146	$manager->desc ("[coro manager]");	153	$manager->{desc} = "[coro manager]";
147	$manager->prio (PRIO_MAX);	154	$manager->prio (PRIO_MAX);
148		155
149	=back	156	=back
150		157
151	=head2 STATIC METHODS	158	=head2 SIMPLE COROUTINE CREATION
152
153	Static methods are actually functions that operate on the current coroutine only.
154		159
155	=over 4	160	=over 4
156		161
157	=item async { ... } [@args...]	162	=item async { ... } [@args...]
158		163
159	Create a new asynchronous coroutine and return it's coroutine object	164	Create a new coroutine and return it's coroutine object (usually
160	(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
161	terminated.	170	terminated.
162		171
		172	The remaining arguments are passed as arguments to the closure.
		173
163	See the C<Coro::State::new> constructor for info about the coroutine	174	See the C<Coro::State::new> constructor for info about the coroutine
164	environment in which coroutines run.	175	environment in which coroutines are executed.
165		176
166	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
167	the coroutine. Likewise, when the coroutine dies, the program will exit,	178	the coroutine. Likewise, when the coroutine dies, the program will exit,
168	just as it would in the main program.	179	just as it would in the main program.
169		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
170	# create a new coroutine that just prints its arguments	184	Example: Create a new coroutine that just prints its arguments.
		185
171	async {	186	async {
172	print "@_\n";	187	print "@_\n";
173	} 1,2,3,4;	188	} 1,2,3,4;
174		189
175	=cut	190	=cut
…		…
181	}	196	}
182		197
183	=item async_pool { ... } [@args...]	198	=item async_pool { ... } [@args...]
184		199
185	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
186	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
187	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 :).
188		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
189	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
190	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
191	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>
192	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,
193	which somehow defeats the purpose of pooling.	213	which somehow defeats the purpose of pooling (but is fine in the
		214	exceptional case).
194		215
195	The priority will be reset to C<0> after each job, tracing will be	216	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	217	disabled, the description will be reset and the default output filehandle
197	gets restored, so you can change alkl these. Otherwise the coroutine will	218	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	219	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	220	stuff such as C<$/> you I<must needs> revert that change, which is most
200	done by using local as in C< local $/ >.	221	simply done by using local as in: C<< local $/ >>.
201		222
202	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
203	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
204	required.	225	coros as required.
205		226
206	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
207	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
208	{ 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
209	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
210	(adjustable with $Coro::POOL_RSS) it will also exit.	231	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
211		232
212	=cut	233	=cut
213		234
214	our $POOL_SIZE = 8;	235	our $POOL_SIZE = 8;
215	our $POOL_RSS = 16 * 1024;	236	our $POOL_RSS = 32 * 1024;
216	our @async_pool;	237	our @async_pool;
217		238
218	sub pool_handler {	239	sub pool_handler {
219	my $cb;
220
221	while () {	240	while () {
222	eval {	241	eval {
223	while () {	242	&{&_pool_handler} while 1;
224	_pool_1 $cb;
225	&$cb;
226	_pool_2 $cb;
227	&schedule;
228	}
229	};	243	};
230		244
231	last if $@ eq "\3async_pool terminate\2\n";
232	warn $@ if $@;	245	warn $@ if $@;
233	}	246	}
234	}	247	}
235		248
236	sub async_pool(&@) {	249	=back
237	# this is also inlined into the unlock_scheduler
238	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
239		250
240	$coro->{_invoke} = [@_];	251	=head2 STATIC METHODS
241	$coro->ready;
242		252
243	$coro	253	Static methods are actually functions that operate on the current coroutine.
244	}	254
		255	=over 4
245		256
246	=item schedule	257	=item schedule
247		258
248	Calls the scheduler. Please note that the current coroutine will not be put	259	Calls the scheduler. The scheduler will find the next coroutine that is
		260	to be run from the ready queue and switches to it. The next coroutine
		261	to be run is simply the one with the highest priority that is longest
		262	in its ready queue. If there is no coroutine ready, it will clal the
		263	C<$Coro::idle> hook.
		264
		265	Please note that the current coroutine will I<not> be put into the ready
249	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
250	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 >>,
251	ready.	268	thus waking you up.
252		269
253	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.
254		277
255	{	278	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		279
272	=item cede	280	=item cede
273		281
274	"Cede" to other coroutines. This function puts the current coroutine into the	282	"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	283	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.	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.
277		289
278	=item Coro::cede_notself	290	=item Coro::cede_notself
279		291
280	Works like cede, but is not exported by default and will cede to any	292	Works like cede, but is not exported by default and will cede to I<any>
281	coroutine, regardless of priority, once.	293	coroutine, regardless of priority. This is useful sometimes to ensure
		294	progress is made.
282		295
283	=item terminate [arg...]	296	=item terminate [arg...]
284		297
285	Terminates the current coroutine with the given status values (see L<cancel>).	298	Terminates the current coroutine with the given status values (see L<cancel>).
286		299
…		…
288		301
289	Kills/terminates/cancels all coroutines except the currently running	302	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	303	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.	304	usually only one of them should inherit the running coroutines.
292		305
293	=cut	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.
294		309
295	sub terminate {	310	=cut
296	$current->cancel (@_);
297	}
298		311
299	sub killall {	312	sub killall {
300	for (Coro::State::list) {	313	for (Coro::State::list) {
301	$_->cancel	314	$_->cancel
302	if $_ != $current && UNIVERSAL::isa $_, "Coro";	315	if $_ != $current && UNIVERSAL::isa $_, "Coro";
…		…
305		318
306	=back	319	=back
307		320
308	=head2 COROUTINE METHODS	321	=head2 COROUTINE METHODS
309		322
310	These are the methods you can call on coroutine objects.	323	These are the methods you can call on coroutine objects (or to create
		324	them).
311		325
312	=over 4	326	=over 4
313		327
314	=item new Coro \&sub [, @args...]	328	=item new Coro \&sub [, @args...]
315		329
316	Create a new coroutine and return it. When the sub returns the coroutine	330	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	331	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	332	called. To make the coroutine run you must first put it into the ready
319	by calling the ready method.	333	queue by calling the ready method.
320		334
321	See C<async> and C<Coro::State::new> for additional info about the	335	See C<async> and C<Coro::State::new> for additional info about the
322	coroutine environment.	336	coroutine environment.
323		337
324	=cut	338	=cut
325		339
326	sub _run_coro {	340	sub _terminate {
327	terminate &{+shift};	341	terminate &{+shift};
328	}	342	}
329		343
330	sub new {
331	my $class = shift;
332
333	$class->SUPER::new (\&_run_coro, @_)
334	}
335
336	=item $success = $coroutine->ready	344	=item $success = $coroutine->ready
337		345
338	Put the given coroutine into the ready queue (according to it's priority)	346	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	347	queue for each priority) and return true. If the coroutine is already in
340	and return false.	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.
341		353
342	=item $is_ready = $coroutine->is_ready	354	=item $is_ready = $coroutine->is_ready
343		355
344	Return wether the coroutine is currently the ready queue or not,	356	Return whether the coroutine is currently the ready queue or not,
345		357
346	=item $coroutine->cancel (arg...)	358	=item $coroutine->cancel (arg...)
347		359
348	Terminates the given coroutine and makes it return the given arguments as	360	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	361	status (default: the empty list). Never returns if the coroutine is the
…		…
351		363
352	=cut	364	=cut
353		365
354	sub cancel {	366	sub cancel {
355	my $self = shift;	367	my $self = shift;
356	$self->{_status} = [@_];
357		368
358	if ($current == $self) {	369	if ($current == $self) {
359	push @destroy, $self;	370	terminate @_;
360	$manager->ready;
361	&schedule while 1;
362	} else {	371	} else {
		372	$self->{_status} = [@_];
363	$self->_cancel;	373	$self->_cancel;
364	}	374	}
365	}	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).
366		418
367	=item $coroutine->join	419	=item $coroutine->join
368		420
369	Wait until the coroutine terminates and return any values given to the	421	Wait until the coroutine terminates and return any values given to the
370	C<terminate> or C<cancel> functions. C<join> can be called concurrently	422	C<terminate> or C<cancel> functions. C<join> can be called concurrently
371	from multiple coroutines.	423	from multiple coroutines, and all will be resumed and given the status
		424	return once the C<$coroutine> terminates.
372		425
373	=cut	426	=cut
374		427
375	sub join {	428	sub join {
376	my $self = shift;	429	my $self = shift;
…		…
391		444
392	=item $coroutine->on_destroy (\&cb)	445	=item $coroutine->on_destroy (\&cb)
393		446
394	Registers a callback that is called when this coroutine gets destroyed,	447	Registers a callback that is called when this coroutine gets destroyed,
395	but before it is joined. The callback gets passed the terminate arguments,	448	but before it is joined. The callback gets passed the terminate arguments,
396	if any.	449	if any, and I<must not> die, under any circumstances.
397		450
398	=cut	451	=cut
399		452
400	sub on_destroy {	453	sub on_destroy {
401	my ($self, $cb) = @_;	454	my ($self, $cb) = @_;
…		…
431	higher values mean lower priority, just as in unix).	484	higher values mean lower priority, just as in unix).
432		485
433	=item $olddesc = $coroutine->desc ($newdesc)	486	=item $olddesc = $coroutine->desc ($newdesc)
434		487
435	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
436	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.
437		491
438	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
439	can modify this member directly if you wish.	493	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		494
457	=cut	495	=cut
458		496
459	sub desc {	497	sub desc {
460	my $old = $_[0]{desc};	498	my $old = $_[0]{desc};
461	$_[0]{desc} = $_[1] if @_ > 1;	499	$_[0]{desc} = $_[1] if @_ > 1;
462	$old;	500	$old;
463	}	501	}
464		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
465	=back	508	=back
466		509
467	=head2 GLOBAL FUNCTIONS	510	=head2 GLOBAL FUNCTIONS
468		511
469	=over 4	512	=over 4
470		513
471	=item Coro::nready	514	=item Coro::nready
472		515
473	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,
474	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
475	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>
476	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
477	that wakes up some coroutines.	521	coroutines.
478		522
479	=item my $guard = Coro::guard { ... }	523	=item my $guard = Coro::guard { ... }
480		524
481	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
482	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
…		…
511		555
512		556
513	=item unblock_sub { ... }	557	=item unblock_sub { ... }
514		558
515	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,
516	returning the new coderef. This means that the new coderef will return	560	returning a new coderef. Unblocking means that calling the new coderef
517	immediately without blocking, returning nothing, while the original code	561	will return immediately without blocking, returning nothing, while the
518	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.
519		564
520	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
521	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
522	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,
523	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>.
524		570
525	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
526	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
527	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
528	disk.	574	disk, for example.
529		575
530	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
531	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>.
532		588
533	=cut	589	=cut
534		590
535	our @unblock_queue;	591	our @unblock_queue;
536		592
…		…
539	# return immediately and can be reused) and because we cannot cede	595	# return immediately and can be reused) and because we cannot cede
540	# inside an event callback.	596	# inside an event callback.
541	our $unblock_scheduler = new Coro sub {	597	our $unblock_scheduler = new Coro sub {
542	while () {	598	while () {
543	while (my $cb = pop @unblock_queue) {	599	while (my $cb = pop @unblock_queue) {
544	# this is an inlined copy of async_pool	600	&async_pool (@$cb);
545	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
546		601
547	$coro->{_invoke} = $cb;
548	$coro->ready;
549	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;
550	}	606	}
551	schedule; # sleep well	607	schedule; # sleep well
552	}	608	}
553	};	609	};
554	$unblock_scheduler->desc ("[unblock_sub scheduler]");	610	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
555		611
556	sub unblock_sub(&) {	612	sub unblock_sub(&) {
557	my $cb = shift;	613	my $cb = shift;
558		614
559	sub {	615	sub {
560	unshift @unblock_queue, [$cb, @_];	616	unshift @unblock_queue, [$cb, @_];
561	$unblock_scheduler->ready;	617	$unblock_scheduler->ready;
562	}	618	}
563	}	619	}
564		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
565	=back	640	=back
566		641
567	=cut	642	=cut
568		643
569	1;	644	1;
570		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
571	=head1 BUGS/LIMITATIONS	712	=head1 BUGS/LIMITATIONS
572		713
573	- you must make very sure that no coro is still active on global	714	=over 4
574	destruction. very bad things might happen otherwise (usually segfaults).
575		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
576	- 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
577	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
578	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
579	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
580		744
581	=head1 SEE ALSO	745	=head1 SEE ALSO
582		746
583	Lower level Configuration, Coroutine Environment: L<Coro::State>.	747	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
584		748
585	Debugging: L<Coro::Debug>.	749	Debugging: L<Coro::Debug>.
586		750
587	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	751	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
588		752
589	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>.
590		754
591	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	755	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
592		756
593	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	757	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
594		758
595	Embedding: L<Coro::MakeMaker>.	759	XS API: L<Coro::MakeMaker>.
		760
		761	Low level Configuration, Coroutine Environment: L<Coro::State>.
596		762
597	=head1 AUTHOR	763	=head1 AUTHOR
598		764
599	Marc Lehmann <schmorp@schmorp.de>	765	Marc Lehmann <schmorp@schmorp.de>
600	http://home.schmorp.de/	766	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 1.233 by root, Fri Nov 21 06:02:07 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 1.233 by root, Fri Nov 21 06:02:07 2008 UTC