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

Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.182 by root, Fri May 9 22:29:05 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	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 $VERSION = 4.6;
47		72
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	73	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	74	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	75	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	76	);
52	our @EXPORT_OK = @{$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, because the program has no other way to continue.	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 wake up a	126	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
126	coroutine so the scheduler can run it.	127	coroutine so the scheduler can run it.
127		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
128	Please note that if your callback recursively invokes perl (e.g. for event	137	Please note that if your callback recursively invokes perl (e.g. for event
129	handlers), then it must be prepared to be called recursively.	138	handlers), then it must be prepared to be called recursively itself.
130		139
131	=cut	140	=cut
132		141
133	$idle = sub {	142	$idle = sub {
134	print STDERR "FATAL: deadlock detected\n";	143	require Carp;
135	exit (51);	144	Carp::croak ("FATAL: deadlock detected");
136	};	145	};
		146
		147	sub _cancel {
		148	my ($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	}
137		158
138	# this coroutine is necessary because a coroutine	159	# this coroutine is necessary because a coroutine
139	# cannot destroy itself.	160	# cannot destroy itself.
140	my @destroy;	161	my @destroy;
		162	my $manager;
		163
141	my $manager; $manager = new Coro sub {	164	$manager = new Coro sub {
142	while () {	165	while () {
143	# by overwriting the state object with the manager we destroy it	166	(shift @destroy)->_cancel
144	# while still being able to schedule this coroutine (in case it has
145	# been readied multiple times. this is harmless since the manager
146	# can be called as many times as neccessary and will always
147	# remove itself from the runqueue
148	while (@destroy) {	167	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		168
153	# the next line destroys the coro state, but keeps the
154	# coroutine itself intact (we basically make it a zombie
155	# coroutine that always runs the manager thread, so it's possible
156	# to transfer() to this coroutine).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	169	&schedule;
160	}	170	}
161	};	171	};
162		172	$manager->desc ("[coro manager]");
163	# static methods. not really.	173	$manager->prio (PRIO_MAX);
164		174
165	=back	175	=back
166		176
167	=head2 STATIC METHODS	177	=head2 SIMPLE COROUTINE CREATION
168
169	Static methods are actually functions that operate on the current coroutine only.
170		178
171	=over 4	179	=over 4
172		180
173	=item async { ... } [@args...]	181	=item async { ... } [@args...]
174		182
175	Create a new asynchronous coroutine and return it's coroutine object	183	Create a new coroutine and return it's coroutine object (usually
176	(usually unused). When the sub returns the new coroutine 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
177	terminated.	189	terminated.
178		190
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	191	The remaining arguments are passed as arguments to the closure.
180		192
181	When the coroutine dies, the program will exit, just as in the main	193	See the C<Coro::State::new> constructor for info about the coroutine
182	program.	194	environment in which coroutines are executed.
183		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
184	# create a new coroutine that just prints its arguments	203	Example: Create a new coroutine that just prints its arguments.
		204
185	async {	205	async {
186	print "@_\n";	206	print "@_\n";
187	} 1,2,3,4;	207	} 1,2,3,4;
188		208
189	=cut	209	=cut
190		210
191	sub async(&@) {	211	sub async(&@) {
192	my $pid = new Coro @_;	212	my $coro = new Coro @_;
193	$pid->ready;	213	$coro->ready;
194	$pid	214	$coro
195	}	215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join on it (although you are allowed to), and you get a
		221	coroutine that might have executed other code already (which can be good
		222	or bad :).
		223
		224	On the plus side, this function is faster than creating (and destroying)
		225	a completely new coroutine, so if you need a lot of generic coroutines in
		226	quick successsion, use C<async_pool>, not C<async>.
		227
		228	The code block is executed in an C<eval> context and a warning will be
		229	issued in case of an exception instead of terminating the program, as
		230	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		231	will not work in the expected way, unless you call terminate or cancel,
		232	which somehow defeats the purpose of pooling (but is fine in the
		233	exceptional case).
		234
		235	The priority will be reset to C<0> after each run, tracing will be
		236	disabled, the description will be reset and the default output filehandle
		237	gets restored, so you can change all these. Otherwise the coroutine will
		238	be re-used "as-is": most notably if you change other per-coroutine global
		239	stuff such as C<$/> 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	last if $@ eq "\3async_pool terminate\2\n";
		272	warn $@ if $@;
		273	}
		274	}
		275
		276	sub async_pool(&@) {
		277	# this is also inlined into the unlock_scheduler
		278	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		279
		280	$coro->{_invoke} = [@_];
		281	$coro->ready;
		282
		283	$coro
		284	}
		285
		286	=back
		287
		288	=head2 STATIC METHODS
		289
		290	Static methods are actually functions that operate on the current coroutine.
		291
		292	=over 4
196		293
197	=item schedule	294	=item schedule
198		295
199	Calls the scheduler. Please note that the current coroutine will not be put	296	Calls the scheduler. The scheduler will find the next coroutine that is
		297	to be run from the ready queue and switches to it. The next coroutine
		298	to be run is simply the one with the highest priority that is longest
		299	in its ready queue. If there is no coroutine ready, it will clal the
		300	C<$Coro::idle> hook.
		301
		302	Please note that the current coroutine will I<not> be put into the ready
200	into the ready queue, so calling this function usually means you will	303	queue, so calling this function usually means you will never be called
201	never be called again unless something else (e.g. an event handler) calls	304	again unless something else (e.g. an event handler) calls C<< ->ready >>,
202	ready.	305	thus waking you up.
		306
		307	This makes C<schedule> I<the> generic method to use to block the current
		308	coroutine and wait for events: first you remember the current coroutine in
		309	a variable, then arrange for some callback of yours to call C<< ->ready
		310	>> on that once some event happens, and last you call C<schedule> to put
		311	yourself to sleep. Note that a lot of things can wake your coroutine up,
		312	so you need to check wether the event indeed happened, e.g. by storing the
		313	status in a variable.
203		314
204	The canonical way to wait on external events is this:	315	The canonical way to wait on external events is this:
205		316
206	{	317	{
207	# remember current coroutine	318	# remember current coroutine
…		…
212	# wake up sleeping coroutine	323	# wake up sleeping coroutine
213	$current->ready;	324	$current->ready;
214	undef $current;	325	undef $current;
215	};	326	};
216		327
217	# call schedule until event occured.	328	# call schedule until event occurred.
218	# in case we are woken up for other reasons	329	# in case we are woken up for other reasons
219	# (current still defined), loop.	330	# (current still defined), loop.
220	Coro::schedule while $current;	331	Coro::schedule while $current;
221	}	332	}
222		333
223	=item cede	334	=item cede
224		335
225	"Cede" to other coroutines. This function puts the current coroutine into the	336	"Cede" to other coroutines. This function puts the current coroutine into
226	ready queue and calls C<schedule>, which has the effect of giving up the	337	the ready queue and calls C<schedule>, which has the effect of giving
227	current "timeslice" to other coroutines of the same or higher priority.	338	up the current "timeslice" to other coroutines of the same or higher
		339	priority. Once your coroutine gets its turn again it will automatically be
		340	resumed.
		341
		342	This function is often called C<yield> in other languages.
		343
		344	=item Coro::cede_notself
		345
		346	Works like cede, but is not exported by default and will cede to I<any>
		347	coroutine, regardless of priority. This is useful sometimes to ensure
		348	progress is made.
228		349
229	=item terminate [arg...]	350	=item terminate [arg...]
230		351
231	Terminates the current coroutine with the given status values (see L<cancel>).	352	Terminates the current coroutine with the given status values (see L<cancel>).
		353
		354	=item killall
		355
		356	Kills/terminates/cancels all coroutines except the currently running
		357	one. This is useful after a fork, either in the child or the parent, as
		358	usually only one of them should inherit the running coroutines.
		359
		360	Note that while this will try to free some of the main programs resources,
		361	you cnanot free all of them, so if a coroutine that is not the main
		362	program calls this function, there will be some one-time resource leak.
232		363
233	=cut	364	=cut
234		365
235	sub terminate {	366	sub terminate {
236	$current->cancel (@_);	367	$current->cancel (@_);
237	}	368	}
238		369
		370	sub killall {
		371	for (Coro::State::list) {
		372	$_->cancel
		373	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		374	}
		375	}
		376
239	=back	377	=back
240		378
241	# dynamic methods
242
243	=head2 COROUTINE METHODS	379	=head2 COROUTINE METHODS
244		380
245	These are the methods you can call on coroutine objects.	381	These are the methods you can call on coroutine objects (or to create
		382	them).
246		383
247	=over 4	384	=over 4
248		385
249	=item new Coro \&sub [, @args...]	386	=item new Coro \&sub [, @args...]
250		387
251	Create a new coroutine and return it. When the sub returns the coroutine	388	Create a new coroutine and return it. When the sub returns, the coroutine
252	automatically terminates as if C<terminate> with the returned values were	389	automatically terminates as if C<terminate> with the returned values were
253	called. To make the coroutine run you must first put it into the ready queue	390	called. To make the coroutine run you must first put it into the ready
254	by calling the ready method.	391	queue by calling the ready method.
255		392
256	Calling C<exit> in a coroutine will not work correctly, so do not do that.	393	See C<async> and C<Coro::State::new> for additional info about the
		394	coroutine environment.
257		395
258	=cut	396	=cut
259		397
260	sub _new_coro {	398	sub _run_coro {
261	terminate &{+shift};	399	terminate &{+shift};
262	}	400	}
263		401
264	sub new {	402	sub new {
265	my $class = shift;	403	my $class = shift;
266		404
267	$class->SUPER::new (\&_new_coro, @_)	405	$class->SUPER::new (\&_run_coro, @_)
268	}	406	}
269		407
270	=item $success = $coroutine->ready	408	=item $success = $coroutine->ready
271		409
272	Put the given coroutine into the ready queue (according to it's priority)	410	Put the given coroutine into the end of its ready queue (there is one
273	and return true. If the coroutine is already in the ready queue, do nothing	411	queue for each priority) and return true. If the coroutine is already in
274	and return false.	412	the ready queue, do nothing and return false.
		413
		414	This ensures that the scheduler will resume this coroutine automatically
		415	once all the coroutines of higher priority and all coroutines of the same
		416	priority that were put into the ready queue earlier have been resumed.
275		417
276	=item $is_ready = $coroutine->is_ready	418	=item $is_ready = $coroutine->is_ready
277		419
278	Return wether the coroutine is currently the ready queue or not,	420	Return wether the coroutine is currently the ready queue or not,
279		421
280	=item $coroutine->cancel (arg...)	422	=item $coroutine->cancel (arg...)
281		423
282	Terminates the given coroutine and makes it return the given arguments as	424	Terminates the given coroutine and makes it return the given arguments as
283	status (default: the empty list).	425	status (default: the empty list). Never returns if the coroutine is the
		426	current coroutine.
284		427
285	=cut	428	=cut
286		429
287	sub cancel {	430	sub cancel {
288	my $self = shift;	431	my $self = shift;
289	$self->{status} = [@_];	432	$self->{_status} = [@_];
		433
		434	if ($current == $self) {
290	push @destroy, $self;	435	push @destroy, $self;
291	$manager->ready;	436	$manager->ready;
292	&schedule if $current == $self;	437	&schedule while 1;
		438	} else {
		439	$self->_cancel;
		440	}
293	}	441	}
294		442
295	=item $coroutine->join	443	=item $coroutine->join
296		444
297	Wait until the coroutine terminates and return any values given to the	445	Wait until the coroutine terminates and return any values given to the
298	C<terminate> or C<cancel> functions. C<join> can be called multiple times	446	C<terminate> or C<cancel> functions. C<join> can be called concurrently
299	from multiple coroutine.	447	from multiple coroutines, and all will be resumed and given the status
		448	return once the C<$coroutine> terminates.
300		449
301	=cut	450	=cut
302		451
303	sub join {	452	sub join {
304	my $self = shift;	453	my $self = shift;
		454
305	unless ($self->{status}) {	455	unless ($self->{_status}) {
306	push @{$self->{join}}, $current;	456	my $current = $current;
307	&schedule;	457
		458	push @{$self->{_on_destroy}}, sub {
		459	$current->ready;
		460	undef $current;
		461	};
		462
		463	&schedule while $current;
308	}	464	}
		465
309	wantarray ? @{$self->{status}} : $self->{status}[0];	466	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		467	}
		468
		469	=item $coroutine->on_destroy (\&cb)
		470
		471	Registers a callback that is called when this coroutine gets destroyed,
		472	but before it is joined. The callback gets passed the terminate arguments,
		473	if any, and I<must not> die, under any circumstances.
		474
		475	=cut
		476
		477	sub on_destroy {
		478	my ($self, $cb) = @_;
		479
		480	push @{ $self->{_on_destroy} }, $cb;
310	}	481	}
311		482
312	=item $oldprio = $coroutine->prio ($newprio)	483	=item $oldprio = $coroutine->prio ($newprio)
313		484
314	Sets (or gets, if the argument is missing) the priority of the	485	Sets (or gets, if the argument is missing) the priority of the
…		…
339	=item $olddesc = $coroutine->desc ($newdesc)	510	=item $olddesc = $coroutine->desc ($newdesc)
340		511
341	Sets (or gets in case the argument is missing) the description for this	512	Sets (or gets in case the argument is missing) the description for this
342	coroutine. This is just a free-form string you can associate with a coroutine.	513	coroutine. This is just a free-form string you can associate with a coroutine.
343		514
		515	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		516	can modify this member directly if you wish.
		517
		518	=item $coroutine->throw ([$scalar])
		519
		520	If C<$throw> is specified and defined, it will be thrown as an exception
		521	inside the coroutine at the next convinient point in time (usually after
		522	it gains control at the next schedule/transfer/cede). Otherwise clears the
		523	exception object.
		524
		525	The exception object will be thrown "as is" with the specified scalar in
		526	C<$@>, i.e. if it is a string, no line number or newline will be appended
		527	(unlike with C<die>).
		528
		529	This can be used as a softer means than C<cancel> to ask a coroutine to
		530	end itself, although there is no guarentee that the exception will lead to
		531	termination, and if the exception isn't caught it might well end the whole
		532	program.
		533
344	=cut	534	=cut
345		535
346	sub desc {	536	sub desc {
347	my $old = $_[0]{desc};	537	my $old = $_[0]{desc};
348	$_[0]{desc} = $_[1] if @_ > 1;	538	$_[0]{desc} = $_[1] if @_ > 1;
349	$old;	539	$old;
350	}	540	}
351		541
352	=back	542	=back
353		543
354	=head2 UTILITY FUNCTIONS	544	=head2 GLOBAL FUNCTIONS
355		545
356	=over 4	546	=over 4
357		547
		548	=item Coro::nready
		549
		550	Returns the number of coroutines that are currently in the ready state,
		551	i.e. that can be switched to by calling C<schedule> directory or
		552	indirectly. The value C<0> means that the only runnable coroutine is the
		553	currently running one, so C<cede> would have no effect, and C<schedule>
		554	would cause a deadlock unless there is an idle handler that wakes up some
		555	coroutines.
		556
		557	=item my $guard = Coro::guard { ... }
		558
		559	This creates and returns a guard object. Nothing happens until the object
		560	gets destroyed, in which case the codeblock given as argument will be
		561	executed. This is useful to free locks or other resources in case of a
		562	runtime error or when the coroutine gets canceled, as in both cases the
		563	guard block will be executed. The guard object supports only one method,
		564	C<< ->cancel >>, which will keep the codeblock from being executed.
		565
		566	Example: set some flag and clear it again when the coroutine gets canceled
		567	or the function returns:
		568
		569	sub do_something {
		570	my $guard = Coro::guard { $busy = 0 };
		571	$busy = 1;
		572
		573	# do something that requires $busy to be true
		574	}
		575
		576	=cut
		577
		578	sub guard(&) {
		579	bless \(my $cb = $_[0]), "Coro::guard"
		580	}
		581
		582	sub Coro::guard::cancel {
		583	${$_[0]} = sub { };
		584	}
		585
		586	sub Coro::guard::DESTROY {
		587	${$_[0]}->();
		588	}
		589
		590
358	=item unblock_sub { ... }	591	=item unblock_sub { ... }
359		592
360	This utility function takes a BLOCK or code reference and "unblocks" it,	593	This utility function takes a BLOCK or code reference and "unblocks" it,
361	returning the new coderef. This means that the new coderef will return	594	returning a new coderef. Unblocking means that calling the new coderef
362	immediately without blocking, returning nothing, while the original code	595	will return immediately without blocking, returning nothing, while the
363	ref will be called (with parameters) from within its own coroutine.	596	original code ref will be called (with parameters) from within another
		597	coroutine.
364		598
365	The reason this fucntion exists is that many event libraries (such as the	599	The reason this function exists is that many event libraries (such as the
366	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	600	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
367	of thread-safety). This means you must not block within event callbacks,	601	of thread-safety). This means you must not block within event callbacks,
368	otherwise you might suffer from crashes or worse.	602	otherwise you might suffer from crashes or worse. The only event library
		603	currently known that is safe to use without C<unblock_sub> is L<EV>.
369		604
370	This function allows your callbacks to block by executing them in another	605	This function allows your callbacks to block by executing them in another
371	coroutine where it is safe to block. One example where blocking is handy	606	coroutine where it is safe to block. One example where blocking is handy
372	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	607	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
373	disk.	608	disk, for example.
374		609
375	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	610	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
376	creating event callbacks that want to block.	611	creating event callbacks that want to block.
377		612
378	=cut	613	If your handler does not plan to block (e.g. simply sends a message to
		614	another coroutine, or puts some other coroutine into the ready queue),
		615	there is no reason to use C<unblock_sub>.
379		616
380	our @unblock_pool;	617	=cut
		618
381	our @unblock_queue;	619	our @unblock_queue;
382	our $UNBLOCK_POOL_SIZE = 2;
383		620
384	sub unblock_handler_ {	621	# we create a special coro because we want to cede,
385	while () {	622	# to reduce pressure on the coro pool (because most callbacks
386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	623	# return immediately and can be reused) and because we cannot cede
387	$cb->(@arg);	624	# inside an event callback.
388
389	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
390	push @unblock_pool, $Coro::current;
391	schedule;
392	}
393	}
394
395	our $unblock_scheduler = async {	625	our $unblock_scheduler = new Coro sub {
396	while () {	626	while () {
397	while (my $cb = pop @unblock_queue) {	627	while (my $cb = pop @unblock_queue) {
398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	628	# this is an inlined copy of async_pool
399	$handler->{arg} = $cb;	629	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		630
		631	$coro->{_invoke} = $cb;
400	$handler->ready;	632	$coro->ready;
401	cede;	633	cede; # for short-lived callbacks, this reduces pressure on the coro pool
402	}	634	}
403		635	schedule; # sleep well
404	schedule;
405	}	636	}
406	};	637	};
		638	$unblock_scheduler->desc ("[unblock_sub scheduler]");
407		639
408	sub unblock_sub(&) {	640	sub unblock_sub(&) {
409	my $cb = shift;	641	my $cb = shift;
410		642
411	sub {	643	sub {
412	push @unblock_queue, [$cb, @_];	644	unshift @unblock_queue, [$cb, @_];
413	$unblock_scheduler->ready;	645	$unblock_scheduler->ready;
414	}	646	}
415	}	647	}
416		648
417	=back	649	=back
…		…
420		652
421	1;	653	1;
422		654
423	=head1 BUGS/LIMITATIONS	655	=head1 BUGS/LIMITATIONS
424		656
425	- you must make very sure that no coro is still active on global
426	destruction. very bad things might happen otherwise (usually segfaults).
427
428	- this module is not thread-safe. You should only ever use this module	657	This module is not perl-pseudo-thread-safe. You should only ever use this
429	from the same thread (this requirement might be losened in the future	658	module from the same thread (this requirement might be removed in the
430	to allow per-thread schedulers, but Coro::State does not yet allow	659	future to allow per-thread schedulers, but Coro::State does not yet allow
431	this).	660	this). I recommend disabling thread support and using processes, as this
		661	is much faster and uses less memory.
432		662
433	=head1 SEE ALSO	663	=head1 SEE ALSO
434		664
		665	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		666
		667	Debugging: L<Coro::Debug>.
		668
435	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	669	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
436		670
437	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	671	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
438		672
439	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	673	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
440		674
441	Embedding: L<Coro:MakeMaker>	675	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		676
		677	XS API: L<Coro::MakeMaker>.
		678
		679	Low level Configuration, Coroutine Environment: L<Coro::State>.
442		680
443	=head1 AUTHOR	681	=head1 AUTHOR
444		682
445	Marc Lehmann <schmorp@schmorp.de>	683	Marc Lehmann <schmorp@schmorp.de>
446	http://home.schmorp.de/	684	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs. Revision 1.182 by root, Fri May 9 22:29:05 2008 UTC

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Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.182 by root, Fri May 9 22:29:05 2008 UTC