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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC vs.
Revision 1.223 by root, Tue Nov 18 10:44:07 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 use din this module also	33	on SMP machines. The specific flavor of coroutine used in this module
26	guarentees 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 = '3.3';	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 essentiel 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	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}
120	if $current;
121
122	_set_current $main;
123
124	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
125		106
126	=item $idle	107	=item $Coro::idle
127		108
128	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
129	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
130	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.
131		117
132	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
133	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
134	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
135		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
136	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
137	handlers), then it must be prepared to be called recursively.	131	handlers), then it must be prepared to be called recursively itself.
138		132
139	=cut	133	=cut
140		134
141	$idle = sub {	135	$idle = sub {
142	require Carp;	136	require Carp;
…		…
149	# free coroutine data and mark as destructed	143	# free coroutine data and mark as destructed
150	$self->_destroy	144	$self->_destroy
151	or return;	145	or return;
152		146
153	# call all destruction callbacks	147	# call all destruction callbacks
154	$_->(@{$self->{status}})	148	$_->(@{$self->{_status}})
155	for @{(delete $self->{destroy_cb}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
156	}	150	}
157		151
158	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
159	# cannot destroy itself.	153	# cannot destroy itself.
160	my @destroy;	154	my @destroy;
…		…
166	while @destroy;	160	while @destroy;
167		161
168	&schedule;	162	&schedule;
169	}	163	}
170	};	164	};
171		165	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
173		167
174	# static methods. not really.
175
176	=back	168	=back
177		169
178	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
179
180	Static methods are actually functions that operate on the current coroutine only.
181		171
182	=over 4	172	=over 4
183		173
184	=item async { ... } [@args...]	174	=item async { ... } [@args...]
185		175
186	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
187	(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
188	terminated.	182	terminated.
189		183
190	Calling C<exit> in a coroutine will not work correctly, so do not do that.	184	The remaining arguments are passed as arguments to the closure.
191		185
192	When the coroutine dies, the program will exit, just as in the main	186	See the C<Coro::State::new> constructor for info about the coroutine
193	program.	187	environment in which coroutines are executed.
194		188
		189	Calling C<exit> in a coroutine will do the same as calling exit outside
		190	the coroutine. Likewise, when the coroutine dies, the program will exit,
		191	just as it would in the main program.
		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
195	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
196	async {	198	async {
197	print "@_\n";	199	print "@_\n";
198	} 1,2,3,4;	200	} 1,2,3,4;
199		201
200	=cut	202	=cut
…		…
206	}	208	}
207		209
208	=item async_pool { ... } [@args...]	210	=item async_pool { ... } [@args...]
209		211
210	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
211	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
212	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 :).
213		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
214	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
215	issued in case of an exception instead of terminating the program, as C<async> does.	222	issued in case of an exception instead of terminating the program, as
		223	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		224	will not work in the expected way, unless you call terminate or cancel,
		225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
216		227
217	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
218	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 $/ >>.
219		234
220	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
221	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
222	required.	237	coros as required.
223		238
224	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
225	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
226	terminate }> once per second or so to slowly replenish the pool.	241	{ terminate }> once per second or so to slowly replenish the pool. In
		242	addition to that, when the stacks used by a handler grows larger than 16kb
		243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
227		244
228	=cut	245	=cut
229		246
230	our $POOL_SIZE = 8;	247	our $POOL_SIZE = 8;
		248	our $POOL_RSS = 16 * 1024;
231	our @pool;	249	our @async_pool;
232		250
233	sub pool_handler {	251	sub pool_handler {
		252	my $cb;
		253
234	while () {	254	while () {
235	my ($cb, @arg) = @{ delete $current->{_invoke} };
236
237	eval {	255	eval {
238	$cb->(@arg);	256	while () {
		257	_pool_1 $cb;
		258	&$cb;
		259	_pool_2 $cb;
		260	&schedule;
		261	}
239	};	262	};
		263
		264	if ($@) {
		265	last if $@ eq "\3async_pool terminate\2\n";
240	warn $@ if $@;	266	warn $@;
241		267	}
242	last if @pool >= $POOL_SIZE;	268	}
243	push @pool, $current;	269	}
244
245	$current->prio (0);
246	schedule;
247	}
248	}
249		270
250	sub async_pool(&@) {	271	sub async_pool(&@) {
251	# this is also inlined into the unlock_scheduler	272	# this is also inlined into the unblock_scheduler
252	my $coro = (pop @pool or new Coro \&pool_handler);	273	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
253		274
254	$coro->{_invoke} = [@_];	275	$coro->{_invoke} = [@_];
255	$coro->ready;	276	$coro->ready;
256		277
257	$coro	278	$coro
258	}	279	}
259		280
		281	=back
		282
		283	=head2 STATIC METHODS
		284
		285	Static methods are actually functions that operate on the current coroutine.
		286
		287	=over 4
		288
260	=item schedule	289	=item schedule
261		290
262	Calls the scheduler. Please note that the current coroutine will not be put	291	Calls the scheduler. The scheduler will find the next coroutine that is
		292	to be run from the ready queue and switches to it. The next coroutine
		293	to be run is simply the one with the highest priority that is longest
		294	in its ready queue. If there is no coroutine ready, it will clal the
		295	C<$Coro::idle> hook.
		296
		297	Please note that the current coroutine will I<not> be put into the ready
263	into the ready queue, so calling this function usually means you will	298	queue, so calling this function usually means you will never be called
264	never be called again unless something else (e.g. an event handler) calls	299	again unless something else (e.g. an event handler) calls C<< ->ready >>,
265	ready.	300	thus waking you up.
		301
		302	This makes C<schedule> I<the> generic method to use to block the current
		303	coroutine and wait for events: first you remember the current coroutine in
		304	a variable, then arrange for some callback of yours to call C<< ->ready
		305	>> on that once some event happens, and last you call C<schedule> to put
		306	yourself to sleep. Note that a lot of things can wake your coroutine up,
		307	so you need to check whether the event indeed happened, e.g. by storing the
		308	status in a variable.
266		309
267	The canonical way to wait on external events is this:	310	The canonical way to wait on external events is this:
268		311
269	{	312	{
270	# remember current coroutine	313	# remember current coroutine
…		…
275	# wake up sleeping coroutine	318	# wake up sleeping coroutine
276	$current->ready;	319	$current->ready;
277	undef $current;	320	undef $current;
278	};	321	};
279		322
280	# call schedule until event occured.	323	# call schedule until event occurred.
281	# in case we are woken up for other reasons	324	# in case we are woken up for other reasons
282	# (current still defined), loop.	325	# (current still defined), loop.
283	Coro::schedule while $current;	326	Coro::schedule while $current;
284	}	327	}
285		328
286	=item cede	329	=item cede
287		330
288	"Cede" to other coroutines. This function puts the current coroutine into the	331	"Cede" to other coroutines. This function puts the current coroutine into
289	ready queue and calls C<schedule>, which has the effect of giving up the	332	the ready queue and calls C<schedule>, which has the effect of giving
290	current "timeslice" to other coroutines of the same or higher priority.	333	up the current "timeslice" to other coroutines of the same or higher
		334	priority. Once your coroutine gets its turn again it will automatically be
		335	resumed.
		336
		337	This function is often called C<yield> in other languages.
291		338
292	=item Coro::cede_notself	339	=item Coro::cede_notself
293		340
294	Works like cede, but is not exported by default and will cede to any	341	Works like cede, but is not exported by default and will cede to I<any>
295	coroutine, regardless of priority, once.	342	coroutine, regardless of priority. This is useful sometimes to ensure
		343	progress is made.
296		344
297	=item terminate [arg...]	345	=item terminate [arg...]
298		346
299	Terminates the current coroutine with the given status values (see L<cancel>).	347	Terminates the current coroutine with the given status values (see L<cancel>).
		348
		349	=item killall
		350
		351	Kills/terminates/cancels all coroutines except the currently running
		352	one. This is useful after a fork, either in the child or the parent, as
		353	usually only one of them should inherit the running coroutines.
		354
		355	Note that while this will try to free some of the main programs resources,
		356	you cannot free all of them, so if a coroutine that is not the main
		357	program calls this function, there will be some one-time resource leak.
300		358
301	=cut	359	=cut
302		360
303	sub terminate {	361	sub terminate {
304	$current->cancel (@_);	362	$current->cancel (@_);
305	}	363	}
306		364
		365	sub killall {
		366	for (Coro::State::list) {
		367	$_->cancel
		368	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		369	}
		370	}
		371
307	=back	372	=back
308		373
309	# dynamic methods
310
311	=head2 COROUTINE METHODS	374	=head2 COROUTINE METHODS
312		375
313	These are the methods you can call on coroutine objects.	376	These are the methods you can call on coroutine objects (or to create
		377	them).
314		378
315	=over 4	379	=over 4
316		380
317	=item new Coro \&sub [, @args...]	381	=item new Coro \&sub [, @args...]
318		382
319	Create a new coroutine and return it. When the sub returns the coroutine	383	Create a new coroutine and return it. When the sub returns, the coroutine
320	automatically terminates as if C<terminate> with the returned values were	384	automatically terminates as if C<terminate> with the returned values were
321	called. To make the coroutine run you must first put it into the ready queue	385	called. To make the coroutine run you must first put it into the ready
322	by calling the ready method.	386	queue by calling the ready method.
323		387
324	Calling C<exit> in a coroutine will not work correctly, so do not do that.	388	See C<async> and C<Coro::State::new> for additional info about the
		389	coroutine environment.
325		390
326	=cut	391	=cut
327		392
328	sub _run_coro {	393	sub _run_coro {
329	terminate &{+shift};	394	terminate &{+shift};
…		…
335	$class->SUPER::new (\&_run_coro, @_)	400	$class->SUPER::new (\&_run_coro, @_)
336	}	401	}
337		402
338	=item $success = $coroutine->ready	403	=item $success = $coroutine->ready
339		404
340	Put the given coroutine into the ready queue (according to it's priority)	405	Put the given coroutine into the end of its ready queue (there is one
341	and return true. If the coroutine is already in the ready queue, do nothing	406	queue for each priority) and return true. If the coroutine is already in
342	and return false.	407	the ready queue, do nothing and return false.
		408
		409	This ensures that the scheduler will resume this coroutine automatically
		410	once all the coroutines of higher priority and all coroutines of the same
		411	priority that were put into the ready queue earlier have been resumed.
343		412
344	=item $is_ready = $coroutine->is_ready	413	=item $is_ready = $coroutine->is_ready
345		414
346	Return wether the coroutine is currently the ready queue or not,	415	Return whether the coroutine is currently the ready queue or not,
347		416
348	=item $coroutine->cancel (arg...)	417	=item $coroutine->cancel (arg...)
349		418
350	Terminates the given coroutine and makes it return the given arguments as	419	Terminates the given coroutine and makes it return the given arguments as
351	status (default: the empty list). Never returns if the coroutine is the	420	status (default: the empty list). Never returns if the coroutine is the
…		…
353		422
354	=cut	423	=cut
355		424
356	sub cancel {	425	sub cancel {
357	my $self = shift;	426	my $self = shift;
358	$self->{status} = [@_];	427	$self->{_status} = [@_];
359		428
360	if ($current == $self) {	429	if ($current == $self) {
361	push @destroy, $self;	430	push @destroy, $self;
362	$manager->ready;	431	$manager->ready;
363	&schedule while 1;	432	&schedule while 1;
364	} else {	433	} else {
365	$self->_cancel;	434	$self->_cancel;
366	}	435	}
367	}	436	}
368		437
		438	=item $coroutine->throw ([$scalar])
		439
		440	If C<$throw> is specified and defined, it will be thrown as an exception
		441	inside the coroutine at the next convenient point in time. Otherwise
		442	clears the exception object.
		443
		444	Coro will check for the exception each time a schedule-like-function
		445	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		446	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		447	detect this case and return early in case an exception is pending.
		448
		449	The exception object will be thrown "as is" with the specified scalar in
		450	C<$@>, i.e. if it is a string, no line number or newline will be appended
		451	(unlike with C<die>).
		452
		453	This can be used as a softer means than C<cancel> to ask a coroutine to
		454	end itself, although there is no guarantee that the exception will lead to
		455	termination, and if the exception isn't caught it might well end the whole
		456	program.
		457
		458	You might also think of C<throw> as being the moral equivalent of
		459	C<kill>ing a coroutine with a signal (in this case, a scalar).
		460
369	=item $coroutine->join	461	=item $coroutine->join
370		462
371	Wait until the coroutine terminates and return any values given to the	463	Wait until the coroutine terminates and return any values given to the
372	C<terminate> or C<cancel> functions. C<join> can be called multiple times	464	C<terminate> or C<cancel> functions. C<join> can be called concurrently
373	from multiple coroutine.	465	from multiple coroutines, and all will be resumed and given the status
		466	return once the C<$coroutine> terminates.
374		467
375	=cut	468	=cut
376		469
377	sub join {	470	sub join {
378	my $self = shift;	471	my $self = shift;
379		472
380	unless ($self->{status}) {	473	unless ($self->{_status}) {
381	my $current = $current;	474	my $current = $current;
382		475
383	push @{$self->{destroy_cb}}, sub {	476	push @{$self->{_on_destroy}}, sub {
384	$current->ready;	477	$current->ready;
385	undef $current;	478	undef $current;
386	};	479	};
387		480
388	&schedule while $current;	481	&schedule while $current;
389	}	482	}
390		483
391	wantarray ? @{$self->{status}} : $self->{status}[0];	484	wantarray ? @{$self->{_status}} : $self->{_status}[0];
392	}	485	}
393		486
394	=item $coroutine->on_destroy (\&cb)	487	=item $coroutine->on_destroy (\&cb)
395		488
396	Registers a callback that is called when this coroutine gets destroyed,	489	Registers a callback that is called when this coroutine gets destroyed,
397	but before it is joined. The callback gets passed the terminate arguments,	490	but before it is joined. The callback gets passed the terminate arguments,
398	if any.	491	if any, and I<must not> die, under any circumstances.
399		492
400	=cut	493	=cut
401		494
402	sub on_destroy {	495	sub on_destroy {
403	my ($self, $cb) = @_;	496	my ($self, $cb) = @_;
404		497
405	push @{ $self->{destroy_cb} }, $cb;	498	push @{ $self->{_on_destroy} }, $cb;
406	}	499	}
407		500
408	=item $oldprio = $coroutine->prio ($newprio)	501	=item $oldprio = $coroutine->prio ($newprio)
409		502
410	Sets (or gets, if the argument is missing) the priority of the	503	Sets (or gets, if the argument is missing) the priority of the
…		…
433	higher values mean lower priority, just as in unix).	526	higher values mean lower priority, just as in unix).
434		527
435	=item $olddesc = $coroutine->desc ($newdesc)	528	=item $olddesc = $coroutine->desc ($newdesc)
436		529
437	Sets (or gets in case the argument is missing) the description for this	530	Sets (or gets in case the argument is missing) the description for this
438	coroutine. This is just a free-form string you can associate with a coroutine.	531	coroutine. This is just a free-form string you can associate with a
		532	coroutine.
		533
		534	This method simply sets the C<< $coroutine->{desc} >> member to the given
		535	string. You can modify this member directly if you wish.
439		536
440	=cut	537	=cut
441		538
442	sub desc {	539	sub desc {
443	my $old = $_[0]{desc};	540	my $old = $_[0]{desc};
…		…
452	=over 4	549	=over 4
453		550
454	=item Coro::nready	551	=item Coro::nready
455		552
456	Returns the number of coroutines that are currently in the ready state,	553	Returns the number of coroutines that are currently in the ready state,
457	i.e. that can be swicthed to. The value C<0> means that the only runnable	554	i.e. that can be switched to by calling C<schedule> directory or
		555	indirectly. The value C<0> means that the only runnable coroutine is the
458	coroutine is the currently running one, so C<cede> would have no effect,	556	currently running one, so C<cede> would have no effect, and C<schedule>
459	and C<schedule> would cause a deadlock unless there is an idle handler	557	would cause a deadlock unless there is an idle handler that wakes up some
460	that wakes up some coroutines.	558	coroutines.
461		559
462	=item my $guard = Coro::guard { ... }	560	=item my $guard = Coro::guard { ... }
463		561
464	This creates and returns a guard object. Nothing happens until the objetc	562	This creates and returns a guard object. Nothing happens until the object
465	gets destroyed, in which case the codeblock given as argument will be	563	gets destroyed, in which case the codeblock given as argument will be
466	executed. This is useful to free locks or other resources in case of a	564	executed. This is useful to free locks or other resources in case of a
467	runtime error or when the coroutine gets canceled, as in both cases the	565	runtime error or when the coroutine gets canceled, as in both cases the
468	guard block will be executed. The guard object supports only one method,	566	guard block will be executed. The guard object supports only one method,
469	C<< ->cancel >>, which will keep the codeblock from being executed.	567	C<< ->cancel >>, which will keep the codeblock from being executed.
…		…
494		592
495		593
496	=item unblock_sub { ... }	594	=item unblock_sub { ... }
497		595
498	This utility function takes a BLOCK or code reference and "unblocks" it,	596	This utility function takes a BLOCK or code reference and "unblocks" it,
499	returning the new coderef. This means that the new coderef will return	597	returning a new coderef. Unblocking means that calling the new coderef
500	immediately without blocking, returning nothing, while the original code	598	will return immediately without blocking, returning nothing, while the
501	ref will be called (with parameters) from within its own coroutine.	599	original code ref will be called (with parameters) from within another
		600	coroutine.
502		601
503	The reason this fucntion exists is that many event libraries (such as the	602	The reason this function exists is that many event libraries (such as the
504	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	603	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
505	of thread-safety). This means you must not block within event callbacks,	604	of thread-safety). This means you must not block within event callbacks,
506	otherwise you might suffer from crashes or worse.	605	otherwise you might suffer from crashes or worse. The only event library
		606	currently known that is safe to use without C<unblock_sub> is L<EV>.
507		607
508	This function allows your callbacks to block by executing them in another	608	This function allows your callbacks to block by executing them in another
509	coroutine where it is safe to block. One example where blocking is handy	609	coroutine where it is safe to block. One example where blocking is handy
510	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	610	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
511	disk.	611	disk, for example.
512		612
513	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	613	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
514	creating event callbacks that want to block.	614	creating event callbacks that want to block.
		615
		616	If your handler does not plan to block (e.g. simply sends a message to
		617	another coroutine, or puts some other coroutine into the ready queue),
		618	there is no reason to use C<unblock_sub>.
		619
		620	Note that you also need to use C<unblock_sub> for any other callbacks that
		621	are indirectly executed by any C-based event loop. For example, when you
		622	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		623	provides callbacks that are the result of some event callback, then you
		624	must not block either, or use C<unblock_sub>.
515		625
516	=cut	626	=cut
517		627
518	our @unblock_queue;	628	our @unblock_queue;
519		629
520	# we create a special coro because we want to cede,	630	# we create a special coro because we want to cede,
521	# to reduce pressure on the coro pool (because most callbacks	631	# to reduce pressure on the coro pool (because most callbacks
522	# return immediately and can be reused) and because we cannot cede	632	# return immediately and can be reused) and because we cannot cede
523	# inside an event callback.	633	# inside an event callback.
524	our $unblock_scheduler = async {	634	our $unblock_scheduler = new Coro sub {
525	while () {	635	while () {
526	while (my $cb = pop @unblock_queue) {	636	while (my $cb = pop @unblock_queue) {
527	# this is an inlined copy of async_pool	637	# this is an inlined copy of async_pool
528	my $coro = (pop @pool or new Coro \&pool_handler);	638	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
529		639
530	$coro->{_invoke} = $cb;	640	$coro->{_invoke} = $cb;
531	$coro->ready;	641	$coro->ready;
532	cede; # for short-lived callbacks, this reduces pressure on the coro pool	642	cede; # for short-lived callbacks, this reduces pressure on the coro pool
533	}	643	}
534	schedule; # sleep well	644	schedule; # sleep well
535	}	645	}
536	};	646	};
		647	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
537		648
538	sub unblock_sub(&) {	649	sub unblock_sub(&) {
539	my $cb = shift;	650	my $cb = shift;
540		651
541	sub {	652	sub {
…		…
550		661
551	1;	662	1;
552		663
553	=head1 BUGS/LIMITATIONS	664	=head1 BUGS/LIMITATIONS
554		665
555	- you must make very sure that no coro is still active on global	666	=over 4
556	destruction. very bad things might happen otherwise (usually segfaults).
557		667
		668	=item fork with pthread backend
		669
		670	When Coro is compiled using the pthread backend (which isn't recommended
		671	but required on many BSDs as their libcs are completely broken), then
		672	coroutines will not survive a fork. There is no known workaround except to
		673	fix your libc and use a saner backend.
		674
		675	=item perl process emulation ("threads")
		676
558	- this module is not thread-safe. You should only ever use this module	677	This module is not perl-pseudo-thread-safe. You should only ever use this
559	from the same thread (this requirement might be losened in the future	678	module from the same thread (this requirement might be removed in the
560	to allow per-thread schedulers, but Coro::State does not yet allow	679	future to allow per-thread schedulers, but Coro::State does not yet allow
561	this).	680	this). I recommend disabling thread support and using processes, as having
		681	the windows process emulation enabled under unix roughly halves perl
		682	performance, even when not used.
		683
		684	=item coroutine switching not signal safe
		685
		686	You must not switch to another coroutine from within a signal handler
		687	(only relevant with %SIG - most event libraries provide safe signals).
		688
		689	That means you I<MUST NOT> call any function that might "block" the
		690	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		691	anything that calls those. Everything else, including calling C<ready>,
		692	works.
		693
		694	=back
		695
562		696
563	=head1 SEE ALSO	697	=head1 SEE ALSO
564		698
		699	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		700
		701	Debugging: L<Coro::Debug>.
		702
565	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	703	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
566		704
567	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	705	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
568		706
569	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	707	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
570		708
571	Embedding: L<Coro:MakeMaker>	709	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		710
		711	XS API: L<Coro::MakeMaker>.
		712
		713	Low level Configuration, Coroutine Environment: L<Coro::State>.
572		714
573	=head1 AUTHOR	715	=head1 AUTHOR
574		716
575	Marc Lehmann <schmorp@schmorp.de>	717	Marc Lehmann <schmorp@schmorp.de>
576	http://home.schmorp.de/	718	http://home.schmorp.de/

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Revision 1.223 by root, Tue Nov 18 10:44:07 2008 UTC