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

Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.193 by root, Sun Jun 29 00:28:17 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 process 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	my $lock = new Coro::Semaphore;
19	cede;	22	my $locked;
		23
		24	$lock->down;
		25	$locked = 1;
		26	$lock->up;
20		27
21	=head1 DESCRIPTION	28	=head1 DESCRIPTION
22		29
23	This module collection manages coroutines. Coroutines are similar to	30	This module collection manages coroutines. Coroutines are similar to
24	threads but don't run in parallel.	31	threads but don't (in general) run in parallel at the same time even
		32	on SMP machines. The specific flavor of coroutine used in this module
		33	also guarantees you that it will not switch between coroutines unless
		34	necessary, at easily-identified points in your program, so locking and
		35	parallel access are rarely an issue, making coroutine programming much
		36	safer and easier than threads programming.
25		37
		38	Unlike a normal perl program, however, coroutines allow you to have
		39	multiple running interpreters that share data, which is especially useful
		40	to code pseudo-parallel processes and for event-based programming, such as
		41	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to
		42	learn more.
		43
		44	Coroutines are also useful because Perl has no support for threads (the so
		45	called "threads" that perl offers are nothing more than the (bad) process
		46	emulation coming from the Windows platform: On standard operating systems
		47	they serve no purpose whatsoever, except by making your programs slow and
		48	making them use a lot of memory. Best disable them when building perl, or
		49	aks your software vendor/distributor to do it for you).
		50
26	In this module, coroutines are defined as "callchain + lexical variables	51	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	52	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	53	its own set of lexicals and its own set of perls most important global
29	important global variables.	54	variables (see L<Coro::State> for more configuration).
30		55
31	=cut	56	=cut
32		57
33	package Coro;	58	package Coro;
34		59
…		…
41		66
42	our $idle; # idle handler	67	our $idle; # idle handler
43	our $main; # main coroutine	68	our $main; # main coroutine
44	our $current; # current coroutine	69	our $current; # current coroutine
45		70
46	our $VERSION = '3.0';	71	our $VERSION = 4.743;
47		72
48	our @EXPORT = qw(async cede schedule terminate current);	73	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	74	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	75	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	76	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	77	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53
54	{
55	my @async;
56	my $init;
57
58	# this way of handling attributes simply is NOT scalable ;()
59	sub import {
60	no strict 'refs';
61
62	Coro->export_to_level(1, @_);
63
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);
67	my @attrs;
68	for (@_) {
69	if ($_ eq "Coro") {
70	push @async, $ref;
71	unless ($init++) {
72	eval q{
73	sub INIT {
74	&async(pop @async) while @async;
75	}
76	};
77	}
78	} else {
79	push @attrs, $_;
80	}
81	}
82	return $old ? $old->($package, $ref, @attrs) : @attrs;
83	};
84	}
85
86	}
87		78
88	=over 4	79	=over 4
89		80
90	=item $main	81	=item $Coro::main
91		82
92	This coroutine represents the main program.	83	This variable stores the coroutine object that represents the main
		84	program. While you cna C<ready> it and do most other things you can do to
		85	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		86	wether you are running in the main program or not.
93		87
94	=cut	88	=cut
95		89
96	$main = new Coro;	90	$main = new Coro;
97		91
98	=item $current (or as function: current)	92	=item $Coro::current
99		93
100	The current coroutine (the last coroutine switched to). The initial value	94	The coroutine object representing the current coroutine (the last
		95	coroutine that the Coro scheduler switched to). The initial value is
101	is C<$main> (of course).	96	C<$main> (of course).
102		97
103	This variable is B<strictly> I<read-only>. It is provided for performance	98	This variable is B<strictly> I<read-only>. You can take copies of the
104	reasons. If performance is not essentiel you are encouraged to use the	99	value stored in it and use it as any other coroutine object, but you must
105	C<Coro::current> function instead.	100	not otherwise modify the variable itself.
106		101
107	=cut	102	=cut
		103
		104	$main->{desc} = "[main::]";
108		105
109	# maybe some other module used Coro::Specific before...	106	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	107	$main->{_specific} = $current->{_specific}
112	}	108	if $current;
113		109
114	$current = $main;	110	_set_current $main;
115		111
116	sub current() { $current }	112	sub current() { $current } # [DEPRECATED]
117		113
118	=item $idle	114	=item $Coro::idle
119		115
120	A callback that is called whenever the scheduler finds no ready coroutines	116	This variable is mainly useful to integrate Coro into event loops. It is
121	to run. The default implementation prints "FATAL: deadlock detected" and	117	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
122	exits.	118	pretty low-level functionality.
		119
		120	This variable stores a callback that is called whenever the scheduler
		121	finds no ready coroutines to run. The default implementation prints
		122	"FATAL: deadlock detected" and exits, because the program has no other way
		123	to continue.
123		124
124	This hook is overwritten by modules such as C<Coro::Timer> and	125	This hook is overwritten by modules such as C<Coro::Timer> and
125	C<Coro::Event> to wait on an external event that hopefully wakes up some	126	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
126	coroutine.	127	coroutine so the scheduler can run it.
		128
		129	Note that the callback I<must not>, under any circumstances, block
		130	the current coroutine. Normally, this is achieved by having an "idle
		131	coroutine" that calls the event loop and then blocks again, and then
		132	readying that coroutine in the idle handler.
		133
		134	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		135	technique.
		136
		137	Please note that if your callback recursively invokes perl (e.g. for event
		138	handlers), then it must be prepared to be called recursively itself.
127		139
128	=cut	140	=cut
129		141
130	$idle = sub {	142	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	143	require Carp;
132	exit (51);	144	Carp::croak ("FATAL: deadlock detected");
133	};	145	};
		146
		147	sub _cancel {
		148	my ($self) = @_;
		149
		150	# free coroutine data and mark as destructed
		151	$self->_destroy
		152	or return;
		153
		154	# call all destruction callbacks
		155	$_->(@{$self->{_status}})
		156	for @{(delete $self->{_on_destroy}) \|\| []};
		157	}
134		158
135	# this coroutine is necessary because a coroutine	159	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	160	# cannot destroy itself.
137	my @destroy;	161	my @destroy;
		162	my $manager;
		163
138	my $manager; $manager = new Coro sub {	164	$manager = new Coro sub {
139	while () {	165	while () {
140	# by overwriting the state object with the manager we destroy it	166	(shift @destroy)->_cancel
141	# while still being able to schedule this coroutine (in case it has
142	# been readied multiple times. this is harmless since the manager
143	# can be called as many times as neccessary and will always
144	# remove itself from the runqueue
145	while (@destroy) {	167	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		168
150	# the next line destroys the coro state, but keeps the
151	# process itself intact (we basically make it a zombie
152	# process that always runs the manager thread, so it's possible
153	# to transfer() to this process).
154	$coro->_clone_state_from ($manager);
155	}
156	&schedule;	169	&schedule;
157	}	170	}
158	};	171	};
159		172	$manager->desc ("[coro manager]");
160	# static methods. not really.	173	$manager->prio (PRIO_MAX);
161		174
162	=back	175	=back
163		176
164	=head2 STATIC METHODS	177	=head2 SIMPLE COROUTINE CREATION
165
166	Static methods are actually functions that operate on the current process only.
167		178
168	=over 4	179	=over 4
169		180
170	=item async { ... } [@args...]	181	=item async { ... } [@args...]
171		182
172	Create a new asynchronous process and return it's process object	183	Create a new coroutine and return it's coroutine object (usually
173	(usually unused). When the sub returns the new process is automatically	184	unused). The coroutine will be put into the ready queue, so
		185	it will start running automatically on the next scheduler run.
		186
		187	The first argument is a codeblock/closure that should be executed in the
		188	coroutine. When it returns argument returns the coroutine is automatically
174	terminated.	189	terminated.
175		190
176	When the coroutine dies, the program will exit, just as in the main	191	The remaining arguments are passed as arguments to the closure.
177	program.
178		192
		193	See the C<Coro::State::new> constructor for info about the coroutine
		194	environment in which coroutines are executed.
		195
		196	Calling C<exit> in a coroutine will do the same as calling exit outside
		197	the coroutine. Likewise, when the coroutine dies, the program will exit,
		198	just as it would in the main program.
		199
		200	If you do not want that, you can provide a default C<die> handler, or
		201	simply avoid dieing (by use of C<eval>).
		202
179	# create a new coroutine that just prints its arguments	203	Example: Create a new coroutine that just prints its arguments.
		204
180	async {	205	async {
181	print "@_\n";	206	print "@_\n";
182	} 1,2,3,4;	207	} 1,2,3,4;
183		208
184	=cut	209	=cut
185		210
186	sub async(&@) {	211	sub async(&@) {
187	my $pid = new Coro @_;	212	my $coro = new Coro @_;
188	$pid->ready;	213	$coro->ready;
189	$pid	214	$coro
190	}	215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join on it (although you are allowed to), and you get a
		221	coroutine that might have executed other code already (which can be good
		222	or bad :).
		223
		224	On the plus side, this function is faster than creating (and destroying)
		225	a completely new coroutine, so if you need a lot of generic coroutines in
		226	quick successsion, use C<async_pool>, not C<async>.
		227
		228	The code block is executed in an C<eval> context and a warning will be
		229	issued in case of an exception instead of terminating the program, as
		230	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		231	will not work in the expected way, unless you call terminate or cancel,
		232	which somehow defeats the purpose of pooling (but is fine in the
		233	exceptional case).
		234
		235	The priority will be reset to C<0> after each run, tracing will be
		236	disabled, the description will be reset and the default output filehandle
		237	gets restored, so you can change all these. Otherwise the coroutine will
		238	be re-used "as-is": most notably if you change other per-coroutine global
		239	stuff such as C<$/> you I<must needs> to revert that change, which is most
		240	simply done by using local as in: C< local $/ >.
		241
		242	The pool size is limited to C<8> idle coroutines (this can be adjusted by
		243	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		244	required.
		245
		246	If you are concerned about pooled coroutines growing a lot because a
		247	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		248	{ terminate }> once per second or so to slowly replenish the pool. In
		249	addition to that, when the stacks used by a handler grows larger than 16kb
		250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		251
		252	=cut
		253
		254	our $POOL_SIZE = 8;
		255	our $POOL_RSS = 16 * 1024;
		256	our @async_pool;
		257
		258	sub pool_handler {
		259	my $cb;
		260
		261	while () {
		262	eval {
		263	while () {
		264	_pool_1 $cb;
		265	&$cb;
		266	_pool_2 $cb;
		267	&schedule;
		268	}
		269	};
		270
		271	if ($@) {
		272	last if $@ eq "\3async_pool terminate\2\n";
		273	warn $@;
		274	}
		275	}
		276	}
		277
		278	sub async_pool(&@) {
		279	# this is also inlined into the unlock_scheduler
		280	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		281
		282	$coro->{_invoke} = [@_];
		283	$coro->ready;
		284
		285	$coro
		286	}
		287
		288	=back
		289
		290	=head2 STATIC METHODS
		291
		292	Static methods are actually functions that operate on the current coroutine.
		293
		294	=over 4
191		295
192	=item schedule	296	=item schedule
193		297
194	Calls the scheduler. Please note that the current process will not be put	298	Calls the scheduler. The scheduler will find the next coroutine that is
		299	to be run from the ready queue and switches to it. The next coroutine
		300	to be run is simply the one with the highest priority that is longest
		301	in its ready queue. If there is no coroutine ready, it will clal the
		302	C<$Coro::idle> hook.
		303
		304	Please note that the current coroutine will I<not> be put into the ready
195	into the ready queue, so calling this function usually means you will	305	queue, so calling this function usually means you will never be called
196	never be called again.	306	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		307	thus waking you up.
197		308
198	=cut	309	This makes C<schedule> I<the> generic method to use to block the current
		310	coroutine and wait for events: first you remember the current coroutine in
		311	a variable, then arrange for some callback of yours to call C<< ->ready
		312	>> on that once some event happens, and last you call C<schedule> to put
		313	yourself to sleep. Note that a lot of things can wake your coroutine up,
		314	so you need to check wether the event indeed happened, e.g. by storing the
		315	status in a variable.
		316
		317	The canonical way to wait on external events is this:
		318
		319	{
		320	# remember current coroutine
		321	my $current = $Coro::current;
		322
		323	# register a hypothetical event handler
		324	on_event_invoke sub {
		325	# wake up sleeping coroutine
		326	$current->ready;
		327	undef $current;
		328	};
		329
		330	# call schedule until event occurred.
		331	# in case we are woken up for other reasons
		332	# (current still defined), loop.
		333	Coro::schedule while $current;
		334	}
199		335
200	=item cede	336	=item cede
201		337
202	"Cede" to other processes. This function puts the current process into the	338	"Cede" to other coroutines. This function puts the current coroutine into
203	ready queue and calls C<schedule>, which has the effect of giving up the	339	the ready queue and calls C<schedule>, which has the effect of giving
204	current "timeslice" to other coroutines of the same or higher priority.	340	up the current "timeslice" to other coroutines of the same or higher
		341	priority. Once your coroutine gets its turn again it will automatically be
		342	resumed.
205		343
206	=cut	344	This function is often called C<yield> in other languages.
		345
		346	=item Coro::cede_notself
		347
		348	Works like cede, but is not exported by default and will cede to I<any>
		349	coroutine, regardless of priority. This is useful sometimes to ensure
		350	progress is made.
207		351
208	=item terminate [arg...]	352	=item terminate [arg...]
209		353
210	Terminates the current process with the given status values (see L<cancel>).	354	Terminates the current coroutine with the given status values (see L<cancel>).
		355
		356	=item killall
		357
		358	Kills/terminates/cancels all coroutines except the currently running
		359	one. This is useful after a fork, either in the child or the parent, as
		360	usually only one of them should inherit the running coroutines.
		361
		362	Note that while this will try to free some of the main programs resources,
		363	you cnanot free all of them, so if a coroutine that is not the main
		364	program calls this function, there will be some one-time resource leak.
211		365
212	=cut	366	=cut
213		367
214	sub terminate {	368	sub terminate {
215	$current->cancel (@_);	369	$current->cancel (@_);
216	}	370	}
217		371
		372	sub killall {
		373	for (Coro::State::list) {
		374	$_->cancel
		375	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		376	}
		377	}
		378
218	=back	379	=back
219		380
220	# dynamic methods
221
222	=head2 PROCESS METHODS	381	=head2 COROUTINE METHODS
223		382
224	These are the methods you can call on process objects.	383	These are the methods you can call on coroutine objects (or to create
		384	them).
225		385
226	=over 4	386	=over 4
227		387
228	=item new Coro \&sub [, @args...]	388	=item new Coro \&sub [, @args...]
229		389
230	Create a new process and return it. When the sub returns the process	390	Create a new coroutine and return it. When the sub returns, the coroutine
231	automatically terminates as if C<terminate> with the returned values were	391	automatically terminates as if C<terminate> with the returned values were
232	called. To make the process run you must first put it into the ready queue	392	called. To make the coroutine run you must first put it into the ready
233	by calling the ready method.	393	queue by calling the ready method.
234		394
235	=cut	395	See C<async> and C<Coro::State::new> for additional info about the
		396	coroutine environment.
236		397
		398	=cut
		399
237	sub _new_coro {	400	sub _run_coro {
238	terminate &{+shift};	401	terminate &{+shift};
239	}	402	}
240		403
241	sub new {	404	sub new {
242	my $class = shift;	405	my $class = shift;
243		406
244	$class->SUPER::new (\&_new_coro, @_)	407	$class->SUPER::new (\&_run_coro, @_)
245	}	408	}
246		409
247	=item $process->ready	410	=item $success = $coroutine->ready
248		411
249	Put the given process into the ready queue.	412	Put the given coroutine into the end of its ready queue (there is one
		413	queue for each priority) and return true. If the coroutine is already in
		414	the ready queue, do nothing and return false.
250		415
251	=cut	416	This ensures that the scheduler will resume this coroutine automatically
		417	once all the coroutines of higher priority and all coroutines of the same
		418	priority that were put into the ready queue earlier have been resumed.
252		419
		420	=item $is_ready = $coroutine->is_ready
		421
		422	Return wether the coroutine is currently the ready queue or not,
		423
253	=item $process->cancel (arg...)	424	=item $coroutine->cancel (arg...)
254		425
255	Terminates the given process and makes it return the given arguments as	426	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	427	status (default: the empty list). Never returns if the coroutine is the
		428	current coroutine.
257		429
258	=cut	430	=cut
259		431
260	sub cancel {	432	sub cancel {
261	my $self = shift;	433	my $self = shift;
262	$self->{status} = [@_];	434	$self->{_status} = [@_];
		435
		436	if ($current == $self) {
263	push @destroy, $self;	437	push @destroy, $self;
264	$manager->ready;	438	$manager->ready;
265	&schedule if $current == $self;	439	&schedule while 1;
		440	} else {
		441	$self->_cancel;
		442	}
266	}	443	}
267		444
268	=item $process->join	445	=item $coroutine->join
269		446
270	Wait until the coroutine terminates and return any values given to the	447	Wait until the coroutine terminates and return any values given to the
271	C<terminate> or C<cancel> functions. C<join> can be called multiple times	448	C<terminate> or C<cancel> functions. C<join> can be called concurrently
272	from multiple processes.	449	from multiple coroutines, and all will be resumed and given the status
		450	return once the C<$coroutine> terminates.
273		451
274	=cut	452	=cut
275		453
276	sub join {	454	sub join {
277	my $self = shift;	455	my $self = shift;
		456
278	unless ($self->{status}) {	457	unless ($self->{_status}) {
279	push @{$self->{join}}, $current;	458	my $current = $current;
280	&schedule;	459
		460	push @{$self->{_on_destroy}}, sub {
		461	$current->ready;
		462	undef $current;
		463	};
		464
		465	&schedule while $current;
281	}	466	}
		467
282	wantarray ? @{$self->{status}} : $self->{status}[0];	468	wantarray ? @{$self->{_status}} : $self->{_status}[0];
283	}	469	}
284		470
		471	=item $coroutine->on_destroy (\&cb)
		472
		473	Registers a callback that is called when this coroutine gets destroyed,
		474	but before it is joined. The callback gets passed the terminate arguments,
		475	if any, and I<must not> die, under any circumstances.
		476
		477	=cut
		478
		479	sub on_destroy {
		480	my ($self, $cb) = @_;
		481
		482	push @{ $self->{_on_destroy} }, $cb;
		483	}
		484
285	=item $oldprio = $process->prio ($newprio)	485	=item $oldprio = $coroutine->prio ($newprio)
286		486
287	Sets (or gets, if the argument is missing) the priority of the	487	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	488	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	489	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	490	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	491	to get then):
292		492
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	493	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	494	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	497	current->prio(PRIO_HIGH);
298		498
299	The idle coroutine ($Coro::idle) always has a lower priority than any	499	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	500	existing coroutine.
301		501
302	Changing the priority of the current process will take effect immediately,	502	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	503	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	504	running) will only take effect after the next schedule (of that
305	process). This is a bug that will be fixed in some future version.	505	coroutine). This is a bug that will be fixed in some future version.
306		506
307	=item $newprio = $process->nice ($change)	507	=item $newprio = $coroutine->nice ($change)
308		508
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	509	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	510	higher values mean lower priority, just as in unix).
311		511
312	=item $olddesc = $process->desc ($newdesc)	512	=item $olddesc = $coroutine->desc ($newdesc)
313		513
314	Sets (or gets in case the argument is missing) the description for this	514	Sets (or gets in case the argument is missing) the description for this
315	process. This is just a free-form string you can associate with a process.	515	coroutine. This is just a free-form string you can associate with a coroutine.
		516
		517	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		518	can modify this member directly if you wish.
		519
		520	=item $coroutine->throw ([$scalar])
		521
		522	If C<$throw> is specified and defined, it will be thrown as an exception
		523	inside the coroutine at the next convinient point in time (usually after
		524	it gains control at the next schedule/transfer/cede). Otherwise clears the
		525	exception object.
		526
		527	The exception object will be thrown "as is" with the specified scalar in
		528	C<$@>, i.e. if it is a string, no line number or newline will be appended
		529	(unlike with C<die>).
		530
		531	This can be used as a softer means than C<cancel> to ask a coroutine to
		532	end itself, although there is no guarentee that the exception will lead to
		533	termination, and if the exception isn't caught it might well end the whole
		534	program.
316		535
317	=cut	536	=cut
318		537
319	sub desc {	538	sub desc {
320	my $old = $_[0]{desc};	539	my $old = $_[0]{desc};
…		…
322	$old;	541	$old;
323	}	542	}
324		543
325	=back	544	=back
326		545
		546	=head2 GLOBAL FUNCTIONS
		547
		548	=over 4
		549
		550	=item Coro::nready
		551
		552	Returns the number of coroutines that are currently in the ready state,
		553	i.e. that can be switched to by calling C<schedule> directory or
		554	indirectly. The value C<0> means that the only runnable coroutine is the
		555	currently running one, so C<cede> would have no effect, and C<schedule>
		556	would cause a deadlock unless there is an idle handler that wakes up some
		557	coroutines.
		558
		559	=item my $guard = Coro::guard { ... }
		560
		561	This creates and returns a guard object. Nothing happens until the object
		562	gets destroyed, in which case the codeblock given as argument will be
		563	executed. This is useful to free locks or other resources in case of a
		564	runtime error or when the coroutine gets canceled, as in both cases the
		565	guard block will be executed. The guard object supports only one method,
		566	C<< ->cancel >>, which will keep the codeblock from being executed.
		567
		568	Example: set some flag and clear it again when the coroutine gets canceled
		569	or the function returns:
		570
		571	sub do_something {
		572	my $guard = Coro::guard { $busy = 0 };
		573	$busy = 1;
		574
		575	# do something that requires $busy to be true
		576	}
		577
		578	=cut
		579
		580	sub guard(&) {
		581	bless \(my $cb = $_[0]), "Coro::guard"
		582	}
		583
		584	sub Coro::guard::cancel {
		585	${$_[0]} = sub { };
		586	}
		587
		588	sub Coro::guard::DESTROY {
		589	${$_[0]}->();
		590	}
		591
		592
		593	=item unblock_sub { ... }
		594
		595	This utility function takes a BLOCK or code reference and "unblocks" it,
		596	returning a new coderef. Unblocking means that calling the new coderef
		597	will return immediately without blocking, returning nothing, while the
		598	original code ref will be called (with parameters) from within another
		599	coroutine.
		600
		601	The reason this function exists is that many event libraries (such as the
		602	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		603	of thread-safety). This means you must not block within event callbacks,
		604	otherwise you might suffer from crashes or worse. The only event library
		605	currently known that is safe to use without C<unblock_sub> is L<EV>.
		606
		607	This function allows your callbacks to block by executing them in another
		608	coroutine where it is safe to block. One example where blocking is handy
		609	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		610	disk, for example.
		611
		612	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		613	creating event callbacks that want to block.
		614
		615	If your handler does not plan to block (e.g. simply sends a message to
		616	another coroutine, or puts some other coroutine into the ready queue),
		617	there is no reason to use C<unblock_sub>.
		618
		619	Note that you also need to use C<unblock_sub> for any other callbacks that
		620	are indirectly executed by any C-based event loop. For example, when you
		621	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		622	provides callbacks that are the result of some event callback, then you
		623	must not block either, or use C<unblock_sub>.
		624
		625	=cut
		626
		627	our @unblock_queue;
		628
		629	# we create a special coro because we want to cede,
		630	# to reduce pressure on the coro pool (because most callbacks
		631	# return immediately and can be reused) and because we cannot cede
		632	# inside an event callback.
		633	our $unblock_scheduler = new Coro sub {
		634	while () {
		635	while (my $cb = pop @unblock_queue) {
		636	# this is an inlined copy of async_pool
		637	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		638
		639	$coro->{_invoke} = $cb;
		640	$coro->ready;
		641	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		642	}
		643	schedule; # sleep well
		644	}
		645	};
		646	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		647
		648	sub unblock_sub(&) {
		649	my $cb = shift;
		650
		651	sub {
		652	unshift @unblock_queue, [$cb, @_];
		653	$unblock_scheduler->ready;
		654	}
		655	}
		656
		657	=back
		658
327	=cut	659	=cut
328		660
329	1;	661	1;
330		662
331	=head1 BUGS/LIMITATIONS	663	=head1 BUGS/LIMITATIONS
332		664
333	- you must make very sure that no coro is still active on global
334	destruction. very bad things might happen otherwise (usually segfaults).
335
336	- this module is not thread-safe. You should only ever use this module	665	This module is not perl-pseudo-thread-safe. You should only ever use this
337	from the same thread (this requirement might be losened in the future	666	module from the same thread (this requirement might be removed in the
338	to allow per-thread schedulers, but Coro::State does not yet allow	667	future to allow per-thread schedulers, but Coro::State does not yet allow
339	this).	668	this). I recommend disabling thread support and using processes, as this
		669	is much faster and uses less memory.
340		670
341	=head1 SEE ALSO	671	=head1 SEE ALSO
342		672
		673	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		674
		675	Debugging: L<Coro::Debug>.
		676
343	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	677	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
344		678
345	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	679	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
346		680
347	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	681	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
348		682
349	Embedding: L<Coro:MakeMaker>	683	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		684
		685	XS API: L<Coro::MakeMaker>.
		686
		687	Low level Configuration, Coroutine Environment: L<Coro::State>.
350		688
351	=head1 AUTHOR	689	=head1 AUTHOR
352		690
353	Marc Lehmann <schmorp@schmorp.de>	691	Marc Lehmann <schmorp@schmorp.de>
354	http://home.schmorp.de/	692	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.193 by root, Sun Jun 29 00:28:17 2008 UTC