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

Comparing Coro/Coro.pm (file contents):
Revision 1.95 by root, Sun Dec 3 22:50:06 2006 UTC vs.
Revision 1.198 by root, Sun Sep 21 01:23:26 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 to	31	This module collection manages coroutines. Coroutines are similar to
24	threads but don't run in parallel.	32	threads but don't (in general) run in parallel at the same time even
		33	on SMP machines. The specific flavor of coroutine used in this module
		34	also guarantees you that it will not switch between coroutines unless
		35	necessary, at easily-identified points in your program, so locking and
		36	parallel access are rarely an issue, making coroutine programming much
		37	safer and easier than threads programming.
25		38
		39	Unlike a normal perl program, however, coroutines allow you to have
		40	multiple running interpreters that share data, which is especially useful
		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).
		51
26	In this module, coroutines are defined as "callchain + lexical variables	52	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	53	@_ + $_ + $@ + $/ + 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	54	its own set of lexicals and its own set of perls most important global
29	important global variables.	55	variables (see L<Coro::State> for more configuration).
30		56
31	=cut	57	=cut
32		58
33	package Coro;	59	package Coro;
34		60
…		…
41		67
42	our $idle; # idle handler	68	our $idle; # idle handler
43	our $main; # main coroutine	69	our $main; # main coroutine
44	our $current; # current coroutine	70	our $current; # current coroutine
45		71
46	our $VERSION = '3.01';	72	our $VERSION = 4.746;
47		73
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	77	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	78	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		79
88	=over 4	80	=over 4
89		81
90	=item $main	82	=item $Coro::main
91		83
92	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
93		88
94	=cut	89	=cut
95		90
96	$main = new Coro;	91	$main = new Coro;
97		92
98	=item $current (or as function: current)	93	=item $Coro::current
99		94
100	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
101	is C<$main> (of course).	97	C<$main> (of course).
102		98
103	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
104	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
105	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
106		102
107	=cut	103	=cut
		104
		105	$main->{desc} = "[main::]";
108		106
109	# maybe some other module used Coro::Specific before...	107	# maybe some other module used Coro::Specific before...
110	$main->{specific} = $current->{specific}	108	$main->{_specific} = $current->{_specific}
111	if $current;	109	if $current;
112		110
113	_set_current $main;	111	_set_current $main;
114		112
115	sub current() { $current }	113	sub current() { $current } # [DEPRECATED]
116		114
117	=item $idle	115	=item $Coro::idle
118		116
119	A callback that is called whenever the scheduler finds no ready coroutines	117	This variable is mainly useful to integrate Coro into event loops. It is
120	to run. The default implementation prints "FATAL: deadlock detected" and	118	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
121	exits, because the program has no other way to continue.	119	pretty low-level functionality.
		120
		121	This variable stores a callback that is called whenever the scheduler
		122	finds no ready coroutines to run. The default implementation prints
		123	"FATAL: deadlock detected" and exits, because the program has no other way
		124	to continue.
122		125
123	This hook is overwritten by modules such as C<Coro::Timer> and	126	This hook is overwritten by modules such as C<Coro::Timer> and
124	C<Coro::Event> to wait on an external event that hopefully wake up a	127	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
125	coroutine so the scheduler can run it.	128	coroutine so the scheduler can run it.
126		129
		130	Note that the callback I<must not>, under any circumstances, block
		131	the current coroutine. Normally, this is achieved by having an "idle
		132	coroutine" that calls the event loop and then blocks again, and then
		133	readying that coroutine in the idle handler.
		134
		135	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		136	technique.
		137
127	Please note that if your callback recursively invokes perl (e.g. for event	138	Please note that if your callback recursively invokes perl (e.g. for event
128	handlers), then it must be prepared to be called recursively.	139	handlers), then it must be prepared to be called recursively itself.
129		140
130	=cut	141	=cut
131		142
132	$idle = sub {	143	$idle = sub {
133	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
134	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
135	};	146	};
		147
		148	sub _cancel {
		149	my ($self) = @_;
		150
		151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
		154
		155	# call all destruction callbacks
		156	$_->(@{$self->{_status}})
		157	for @{(delete $self->{_on_destroy}) \|\| []};
		158	}
136		159
137	# this coroutine is necessary because a coroutine	160	# this coroutine is necessary because a coroutine
138	# cannot destroy itself.	161	# cannot destroy itself.
139	my @destroy;	162	my @destroy;
		163	my $manager;
		164
140	my $manager; $manager = new Coro sub {	165	$manager = new Coro sub {
141	while () {	166	while () {
142	# by overwriting the state object with the manager we destroy it	167	(shift @destroy)->_cancel
143	# while still being able to schedule this coroutine (in case it has
144	# been readied multiple times. this is harmless since the manager
145	# can be called as many times as neccessary and will always
146	# remove itself from the runqueue
147	while (@destroy) {	168	while @destroy;
148	my $coro = pop @destroy;
149	$coro->{status} \|\|= [];
150	$_->ready for @{delete $coro->{join} \|\| []};
151		169
152	# the next line destroys the coro state, but keeps the
153	# coroutine itself intact (we basically make it a zombie
154	# coroutine that always runs the manager thread, so it's possible
155	# to transfer() to this coroutine).
156	$coro->_clone_state_from ($manager);
157	}
158	&schedule;	170	&schedule;
159	}	171	}
160	};	172	};
161		173	$manager->desc ("[coro manager]");
162	# static methods. not really.	174	$manager->prio (PRIO_MAX);
163		175
164	=back	176	=back
165		177
166	=head2 STATIC METHODS	178	=head2 SIMPLE COROUTINE CREATION
167
168	Static methods are actually functions that operate on the current coroutine only.
169		179
170	=over 4	180	=over 4
171		181
172	=item async { ... } [@args...]	182	=item async { ... } [@args...]
173		183
174	Create a new asynchronous coroutine and return it's coroutine object	184	Create a new coroutine and return it's coroutine object (usually
175	(usually unused). When the sub returns the new coroutine is automatically	185	unused). The coroutine will be put into the ready queue, so
		186	it will start running automatically on the next scheduler run.
		187
		188	The first argument is a codeblock/closure that should be executed in the
		189	coroutine. When it returns argument returns the coroutine is automatically
176	terminated.	190	terminated.
177		191
178	Calling C<exit> in a coroutine will not work correctly, so do not do that.	192	The remaining arguments are passed as arguments to the closure.
179		193
180	When the coroutine dies, the program will exit, just as in the main	194	See the C<Coro::State::new> constructor for info about the coroutine
181	program.	195	environment in which coroutines are executed.
182		196
		197	Calling C<exit> in a coroutine will do the same as calling exit outside
		198	the coroutine. Likewise, when the coroutine dies, the program will exit,
		199	just as it would in the main program.
		200
		201	If you do not want that, you can provide a default C<die> handler, or
		202	simply avoid dieing (by use of C<eval>).
		203
183	# create a new coroutine that just prints its arguments	204	Example: Create a new coroutine that just prints its arguments.
		205
184	async {	206	async {
185	print "@_\n";	207	print "@_\n";
186	} 1,2,3,4;	208	} 1,2,3,4;
187		209
188	=cut	210	=cut
189		211
190	sub async(&@) {	212	sub async(&@) {
191	my $pid = new Coro @_;	213	my $coro = new Coro @_;
192	$pid->ready;	214	$coro->ready;
193	$pid	215	$coro
194	}	216	}
		217
		218	=item async_pool { ... } [@args...]
		219
		220	Similar to C<async>, but uses a coroutine pool, so you should not call
		221	terminate or join on it (although you are allowed to), and you get a
		222	coroutine that might have executed other code already (which can be good
		223	or bad :).
		224
		225	On the plus side, this function is faster than creating (and destroying)
		226	a completely new coroutine, so if you need a lot of generic coroutines in
		227	quick successsion, use C<async_pool>, not C<async>.
		228
		229	The code block is executed in an C<eval> context and a warning will be
		230	issued in case of an exception instead of terminating the program, as
		231	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		232	will not work in the expected way, unless you call terminate or cancel,
		233	which somehow defeats the purpose of pooling (but is fine in the
		234	exceptional case).
		235
		236	The priority will be reset to C<0> after each run, tracing will be
		237	disabled, the description will be reset and the default output filehandle
		238	gets restored, so you can change all these. Otherwise the coroutine will
		239	be re-used "as-is": most notably if you change other per-coroutine global
		240	stuff such as C<$/> you I<must needs> to revert that change, which is most
		241	simply done by using local as in: C< local $/ >.
		242
		243	The pool size is limited to C<8> idle coroutines (this can be adjusted by
		244	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		245	required.
		246
		247	If you are concerned about pooled coroutines growing a lot because a
		248	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		249	{ terminate }> once per second or so to slowly replenish the pool. In
		250	addition to that, when the stacks used by a handler grows larger than 16kb
		251	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		252
		253	=cut
		254
		255	our $POOL_SIZE = 8;
		256	our $POOL_RSS = 16 * 1024;
		257	our @async_pool;
		258
		259	sub pool_handler {
		260	my $cb;
		261
		262	while () {
		263	eval {
		264	while () {
		265	_pool_1 $cb;
		266	&$cb;
		267	_pool_2 $cb;
		268	&schedule;
		269	}
		270	};
		271
		272	if ($@) {
		273	last if $@ eq "\3async_pool terminate\2\n";
		274	warn $@;
		275	}
		276	}
		277	}
		278
		279	sub async_pool(&@) {
		280	# this is also inlined into the unlock_scheduler
		281	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		282
		283	$coro->{_invoke} = [@_];
		284	$coro->ready;
		285
		286	$coro
		287	}
		288
		289	=back
		290
		291	=head2 STATIC METHODS
		292
		293	Static methods are actually functions that operate on the current coroutine.
		294
		295	=over 4
195		296
196	=item schedule	297	=item schedule
197		298
198	Calls the scheduler. Please note that the current coroutine will not be put	299	Calls the scheduler. The scheduler will find the next coroutine that is
		300	to be run from the ready queue and switches to it. The next coroutine
		301	to be run is simply the one with the highest priority that is longest
		302	in its ready queue. If there is no coroutine ready, it will clal the
		303	C<$Coro::idle> hook.
		304
		305	Please note that the current coroutine will I<not> be put into the ready
199	into the ready queue, so calling this function usually means you will	306	queue, so calling this function usually means you will never be called
200	never be called again unless something else (e.g. an event handler) calls	307	again unless something else (e.g. an event handler) calls C<< ->ready >>,
201	ready.	308	thus waking you up.
		309
		310	This makes C<schedule> I<the> generic method to use to block the current
		311	coroutine and wait for events: first you remember the current coroutine in
		312	a variable, then arrange for some callback of yours to call C<< ->ready
		313	>> on that once some event happens, and last you call C<schedule> to put
		314	yourself to sleep. Note that a lot of things can wake your coroutine up,
		315	so you need to check whether the event indeed happened, e.g. by storing the
		316	status in a variable.
202		317
203	The canonical way to wait on external events is this:	318	The canonical way to wait on external events is this:
204		319
205	{	320	{
206	# remember current coroutine	321	# remember current coroutine
…		…
211	# wake up sleeping coroutine	326	# wake up sleeping coroutine
212	$current->ready;	327	$current->ready;
213	undef $current;	328	undef $current;
214	};	329	};
215		330
216	# call schedule until event occured.	331	# call schedule until event occurred.
217	# in case we are woken up for other reasons	332	# in case we are woken up for other reasons
218	# (current still defined), loop.	333	# (current still defined), loop.
219	Coro::schedule while $current;	334	Coro::schedule while $current;
220	}	335	}
221		336
222	=item cede	337	=item cede
223		338
224	"Cede" to other coroutines. This function puts the current coroutine into the	339	"Cede" to other coroutines. This function puts the current coroutine into
225	ready queue and calls C<schedule>, which has the effect of giving up the	340	the ready queue and calls C<schedule>, which has the effect of giving
226	current "timeslice" to other coroutines of the same or higher priority.	341	up the current "timeslice" to other coroutines of the same or higher
		342	priority. Once your coroutine gets its turn again it will automatically be
		343	resumed.
		344
		345	This function is often called C<yield> in other languages.
		346
		347	=item Coro::cede_notself
		348
		349	Works like cede, but is not exported by default and will cede to I<any>
		350	coroutine, regardless of priority. This is useful sometimes to ensure
		351	progress is made.
227		352
228	=item terminate [arg...]	353	=item terminate [arg...]
229		354
230	Terminates the current coroutine with the given status values (see L<cancel>).	355	Terminates the current coroutine with the given status values (see L<cancel>).
		356
		357	=item killall
		358
		359	Kills/terminates/cancels all coroutines except the currently running
		360	one. This is useful after a fork, either in the child or the parent, as
		361	usually only one of them should inherit the running coroutines.
		362
		363	Note that while this will try to free some of the main programs resources,
		364	you cannot free all of them, so if a coroutine that is not the main
		365	program calls this function, there will be some one-time resource leak.
231		366
232	=cut	367	=cut
233		368
234	sub terminate {	369	sub terminate {
235	$current->cancel (@_);	370	$current->cancel (@_);
236	}	371	}
237		372
		373	sub killall {
		374	for (Coro::State::list) {
		375	$_->cancel
		376	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		377	}
		378	}
		379
238	=back	380	=back
239		381
240	# dynamic methods
241
242	=head2 COROUTINE METHODS	382	=head2 COROUTINE METHODS
243		383
244	These are the methods you can call on coroutine objects.	384	These are the methods you can call on coroutine objects (or to create
		385	them).
245		386
246	=over 4	387	=over 4
247		388
248	=item new Coro \&sub [, @args...]	389	=item new Coro \&sub [, @args...]
249		390
250	Create a new coroutine and return it. When the sub returns the coroutine	391	Create a new coroutine and return it. When the sub returns, the coroutine
251	automatically terminates as if C<terminate> with the returned values were	392	automatically terminates as if C<terminate> with the returned values were
252	called. To make the coroutine run you must first put it into the ready queue	393	called. To make the coroutine run you must first put it into the ready
253	by calling the ready method.	394	queue by calling the ready method.
254		395
255	Calling C<exit> in a coroutine will not work correctly, so do not do that.	396	See C<async> and C<Coro::State::new> for additional info about the
		397	coroutine environment.
256		398
257	=cut	399	=cut
258		400
259	sub _run_coro {	401	sub _run_coro {
260	terminate &{+shift};	402	terminate &{+shift};
…		…
266	$class->SUPER::new (\&_run_coro, @_)	408	$class->SUPER::new (\&_run_coro, @_)
267	}	409	}
268		410
269	=item $success = $coroutine->ready	411	=item $success = $coroutine->ready
270		412
271	Put the given coroutine into the ready queue (according to it's priority)	413	Put the given coroutine into the end of its ready queue (there is one
272	and return true. If the coroutine is already in the ready queue, do nothing	414	queue for each priority) and return true. If the coroutine is already in
273	and return false.	415	the ready queue, do nothing and return false.
		416
		417	This ensures that the scheduler will resume this coroutine automatically
		418	once all the coroutines of higher priority and all coroutines of the same
		419	priority that were put into the ready queue earlier have been resumed.
274		420
275	=item $is_ready = $coroutine->is_ready	421	=item $is_ready = $coroutine->is_ready
276		422
277	Return wether the coroutine is currently the ready queue or not,	423	Return whether the coroutine is currently the ready queue or not,
278		424
279	=item $coroutine->cancel (arg...)	425	=item $coroutine->cancel (arg...)
280		426
281	Terminates the given coroutine and makes it return the given arguments as	427	Terminates the given coroutine and makes it return the given arguments as
282	status (default: the empty list).	428	status (default: the empty list). Never returns if the coroutine is the
		429	current coroutine.
283		430
284	=cut	431	=cut
285		432
286	sub cancel {	433	sub cancel {
287	my $self = shift;	434	my $self = shift;
288	$self->{status} = [@_];	435	$self->{_status} = [@_];
		436
		437	if ($current == $self) {
289	push @destroy, $self;	438	push @destroy, $self;
290	$manager->ready;	439	$manager->ready;
291	&schedule if $current == $self;	440	&schedule while 1;
		441	} else {
		442	$self->_cancel;
		443	}
292	}	444	}
293		445
294	=item $coroutine->join	446	=item $coroutine->join
295		447
296	Wait until the coroutine terminates and return any values given to the	448	Wait until the coroutine terminates and return any values given to the
297	C<terminate> or C<cancel> functions. C<join> can be called multiple times	449	C<terminate> or C<cancel> functions. C<join> can be called concurrently
298	from multiple coroutine.	450	from multiple coroutines, and all will be resumed and given the status
		451	return once the C<$coroutine> terminates.
299		452
300	=cut	453	=cut
301		454
302	sub join {	455	sub join {
303	my $self = shift;	456	my $self = shift;
		457
304	unless ($self->{status}) {	458	unless ($self->{_status}) {
305	push @{$self->{join}}, $current;	459	my $current = $current;
306	&schedule;	460
		461	push @{$self->{_on_destroy}}, sub {
		462	$current->ready;
		463	undef $current;
		464	};
		465
		466	&schedule while $current;
307	}	467	}
		468
308	wantarray ? @{$self->{status}} : $self->{status}[0];	469	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		470	}
		471
		472	=item $coroutine->on_destroy (\&cb)
		473
		474	Registers a callback that is called when this coroutine gets destroyed,
		475	but before it is joined. The callback gets passed the terminate arguments,
		476	if any, and I<must not> die, under any circumstances.
		477
		478	=cut
		479
		480	sub on_destroy {
		481	my ($self, $cb) = @_;
		482
		483	push @{ $self->{_on_destroy} }, $cb;
309	}	484	}
310		485
311	=item $oldprio = $coroutine->prio ($newprio)	486	=item $oldprio = $coroutine->prio ($newprio)
312		487
313	Sets (or gets, if the argument is missing) the priority of the	488	Sets (or gets, if the argument is missing) the priority of the
…		…
338	=item $olddesc = $coroutine->desc ($newdesc)	513	=item $olddesc = $coroutine->desc ($newdesc)
339		514
340	Sets (or gets in case the argument is missing) the description for this	515	Sets (or gets in case the argument is missing) the description for this
341	coroutine. This is just a free-form string you can associate with a coroutine.	516	coroutine. This is just a free-form string you can associate with a coroutine.
342		517
		518	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		519	can modify this member directly if you wish.
		520
		521	=item $coroutine->throw ([$scalar])
		522
		523	If C<$throw> is specified and defined, it will be thrown as an exception
		524	inside the coroutine at the next convinient point in time (usually after
		525	it gains control at the next schedule/transfer/cede). Otherwise clears the
		526	exception object.
		527
		528	The exception object will be thrown "as is" with the specified scalar in
		529	C<$@>, i.e. if it is a string, no line number or newline will be appended
		530	(unlike with C<die>).
		531
		532	This can be used as a softer means than C<cancel> to ask a coroutine to
		533	end itself, although there is no guarentee that the exception will lead to
		534	termination, and if the exception isn't caught it might well end the whole
		535	program.
		536
343	=cut	537	=cut
344		538
345	sub desc {	539	sub desc {
346	my $old = $_[0]{desc};	540	my $old = $_[0]{desc};
347	$_[0]{desc} = $_[1] if @_ > 1;	541	$_[0]{desc} = $_[1] if @_ > 1;
348	$old;	542	$old;
349	}	543	}
350		544
351	=back	545	=back
352		546
353	=head2 UTILITY FUNCTIONS	547	=head2 GLOBAL FUNCTIONS
354		548
355	=over 4	549	=over 4
356		550
		551	=item Coro::nready
		552
		553	Returns the number of coroutines that are currently in the ready state,
		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
		556	currently running one, so C<cede> would have no effect, and C<schedule>
		557	would cause a deadlock unless there is an idle handler that wakes up some
		558	coroutines.
		559
		560	=item my $guard = Coro::guard { ... }
		561
		562	This creates and returns a guard object. Nothing happens until the object
		563	gets destroyed, in which case the codeblock given as argument will be
		564	executed. This is useful to free locks or other resources in case of a
		565	runtime error or when the coroutine gets canceled, as in both cases the
		566	guard block will be executed. The guard object supports only one method,
		567	C<< ->cancel >>, which will keep the codeblock from being executed.
		568
		569	Example: set some flag and clear it again when the coroutine gets canceled
		570	or the function returns:
		571
		572	sub do_something {
		573	my $guard = Coro::guard { $busy = 0 };
		574	$busy = 1;
		575
		576	# do something that requires $busy to be true
		577	}
		578
		579	=cut
		580
		581	sub guard(&) {
		582	bless \(my $cb = $_[0]), "Coro::guard"
		583	}
		584
		585	sub Coro::guard::cancel {
		586	${$_[0]} = sub { };
		587	}
		588
		589	sub Coro::guard::DESTROY {
		590	${$_[0]}->();
		591	}
		592
		593
357	=item unblock_sub { ... }	594	=item unblock_sub { ... }
358		595
359	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,
360	returning the new coderef. This means that the new coderef will return	597	returning a new coderef. Unblocking means that calling the new coderef
361	immediately without blocking, returning nothing, while the original code	598	will return immediately without blocking, returning nothing, while the
362	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.
363		601
364	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
365	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
366	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,
367	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>.
368		607
369	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
370	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
371	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
372	disk.	611	disk, for example.
373		612
374	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
375	creating event callbacks that want to block.	614	creating event callbacks that want to block.
376		615
377	=cut	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>.
378		619
379	our @unblock_pool;	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>.
		625
		626	=cut
		627
380	our @unblock_queue;	628	our @unblock_queue;
381	our $UNBLOCK_POOL_SIZE = 2;
382		629
383	sub unblock_handler_ {	630	# we create a special coro because we want to cede,
384	while () {	631	# to reduce pressure on the coro pool (because most callbacks
385	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	632	# return immediately and can be reused) and because we cannot cede
386	$cb->(@arg);	633	# inside an event callback.
387
388	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
389	push @unblock_pool, $Coro::current;
390	schedule;
391	}
392	}
393
394	our $unblock_scheduler = async {	634	our $unblock_scheduler = new Coro sub {
395	while () {	635	while () {
396	while (my $cb = pop @unblock_queue) {	636	while (my $cb = pop @unblock_queue) {
397	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	637	# this is an inlined copy of async_pool
398	$handler->{arg} = $cb;	638	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		639
		640	$coro->{_invoke} = $cb;
399	$handler->ready;	641	$coro->ready;
400	cede;	642	cede; # for short-lived callbacks, this reduces pressure on the coro pool
401	}	643	}
402		644	schedule; # sleep well
403	schedule;
404	}	645	}
405	};	646	};
		647	$unblock_scheduler->desc ("[unblock_sub scheduler]");
406		648
407	sub unblock_sub(&) {	649	sub unblock_sub(&) {
408	my $cb = shift;	650	my $cb = shift;
409		651
410	sub {	652	sub {
411	push @unblock_queue, [$cb, @_];	653	unshift @unblock_queue, [$cb, @_];
412	$unblock_scheduler->ready;	654	$unblock_scheduler->ready;
413	}	655	}
414	}	656	}
415		657
416	=back	658	=back
…		…
419		661
420	1;	662	1;
421		663
422	=head1 BUGS/LIMITATIONS	664	=head1 BUGS/LIMITATIONS
423		665
424	- you must make very sure that no coro is still active on global
425	destruction. very bad things might happen otherwise (usually segfaults).
426
427	- this module is not thread-safe. You should only ever use this module	666	This module is not perl-pseudo-thread-safe. You should only ever use this
428	from the same thread (this requirement might be losened in the future	667	module from the same thread (this requirement might be removed in the
429	to allow per-thread schedulers, but Coro::State does not yet allow	668	future to allow per-thread schedulers, but Coro::State does not yet allow
430	this).	669	this). I recommend disabling thread support and using processes, as this
		670	is much faster and uses less memory.
431		671
432	=head1 SEE ALSO	672	=head1 SEE ALSO
433		673
		674	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		675
		676	Debugging: L<Coro::Debug>.
		677
434	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	678	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
435		679
436	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	680	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
437		681
438	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	682	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
439		683
440	Embedding: L<Coro:MakeMaker>	684	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		685
		686	XS API: L<Coro::MakeMaker>.
		687
		688	Low level Configuration, Coroutine Environment: L<Coro::State>.
441		689
442	=head1 AUTHOR	690	=head1 AUTHOR
443		691
444	Marc Lehmann <schmorp@schmorp.de>	692	Marc Lehmann <schmorp@schmorp.de>
445	http://home.schmorp.de/	693	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.95 by root, Sun Dec 3 22:50:06 2006 UTC vs. Revision 1.198 by root, Sun Sep 21 01:23:26 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.95 by root, Sun Dec 3 22:50:06 2006 UTC vs.
Revision 1.198 by root, Sun Sep 21 01:23:26 2008 UTC