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

Comparing Coro/Coro.pm (file contents):
Revision 1.103 by root, Thu Jan 4 20:14:19 2007 UTC vs.
Revision 1.225 by root, Wed Nov 19 15:29:57 2008 UTC

…		…
2		2
3	Coro - coroutine process abstraction	3	Coro - coroutine process abstraction
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coroutine
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	This module collection manages coroutines. Coroutines are similar to
24	to threads but don't run in parallel at the same time even on SMP	32	threads but don't (in general) run in parallel at the same time even
25	machines. The specific flavor of coroutine use din this module also	33	on SMP machines. The specific flavor of coroutine used in this module
26	guarentees you that it will not switch between coroutines unless	34	also guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and	35	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much	36	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.	37	safer and easier than threads programming.
30		38
31	(Perl, however, does not natively support real threads but instead does a	39	Unlike a normal perl program, however, coroutines allow you to have
32	very slow and memory-intensive emulation of processes using threads. This	40	multiple running interpreters that share data, which is especially useful
33	is a performance win on Windows machines, and a loss everywhere else).	41	to code pseudo-parallel processes and for event-based programming, such as
		42	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to
		43	learn more.
		44
		45	Coroutines are also useful because Perl has no support for threads (the so
		46	called "threads" that perl offers are nothing more than the (bad) process
		47	emulation coming from the Windows platform: On standard operating systems
		48	they serve no purpose whatsoever, except by making your programs slow and
		49	making them use a lot of memory. Best disable them when building perl, or
		50	aks your software vendor/distributor to do it for you).
34		51
35	In this module, coroutines are defined as "callchain + lexical variables +	52	In this module, coroutines are defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
37	its own set of lexicals and its own set of perls most important global	54	its own set of lexicals and its own set of perls most important global
38	variables.	55	variables (see L<Coro::State> for more configuration).
39		56
40	=cut	57	=cut
41		58
42	package Coro;	59	package Coro;
43		60
44	use strict;	61	use strict qw(vars subs);
45	no warnings "uninitialized";	62	no warnings "uninitialized";
46		63
47	use Coro::State;	64	use Coro::State;
48		65
49	use base qw(Coro::State Exporter);	66	use base qw(Coro::State Exporter);
50		67
51	our $idle; # idle handler	68	our $idle; # idle handler
52	our $main; # main coroutine	69	our $main; # main coroutine
53	our $current; # current coroutine	70	our $current; # current coroutine
54		71
55	our $VERSION = '3.3';	72	our $VERSION = 5.0;
56		73
57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	77	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		79
63	{
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96
97	=over 4	80	=over 4
98		81
99	=item $main	82	=item $Coro::main
100		83
101	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
102		88
103	=cut	89	=cut
104		90
105	$main = new Coro;	91	# $main is now being initialised by Coro::State
106		92
107	=item $current (or as function: current)	93	=item $Coro::current
108		94
109	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	97	C<$Coro::main> (of course).
111		98
112	This variable is B<strictly> I<read-only>. It is provided for performance	99	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essentiel you are encouraged to use the	100	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
115		102
116	=cut	103	=cut
117		104
118	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}
120	if $current;
121
122	_set_current $main;
123
124	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
125		106
126	=item $idle	107	=item $Coro::idle
127		108
128	A callback that is called whenever the scheduler finds no ready coroutines	109	This variable is mainly useful to integrate Coro into event loops. It is
129	to run. The default implementation prints "FATAL: deadlock detected" and	110	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
130	exits, because the program has no other way to continue.	111	pretty low-level functionality.
		112
		113	This variable stores a callback that is called whenever the scheduler
		114	finds no ready coroutines to run. The default implementation prints
		115	"FATAL: deadlock detected" and exits, because the program has no other way
		116	to continue.
131		117
132	This hook is overwritten by modules such as C<Coro::Timer> and	118	This hook is overwritten by modules such as C<Coro::Timer> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a	119	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
135		121
		122	Note that the callback I<must not>, under any circumstances, block
		123	the current coroutine. Normally, this is achieved by having an "idle
		124	coroutine" that calls the event loop and then blocks again, and then
		125	readying that coroutine in the idle handler.
		126
		127	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		128	technique.
		129
136	Please note that if your callback recursively invokes perl (e.g. for event	130	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.	131	handlers), then it must be prepared to be called recursively itself.
138		132
139	=cut	133	=cut
140		134
141	$idle = sub {	135	$idle = sub {
142	require Carp;	136	require Carp;
…		…
149	# free coroutine data and mark as destructed	143	# free coroutine data and mark as destructed
150	$self->_destroy	144	$self->_destroy
151	or return;	145	or return;
152		146
153	# call all destruction callbacks	147	# call all destruction callbacks
154	$_->(@{$self->{status}})	148	$_->(@{$self->{_status}})
155	for @{(delete $self->{destroy_cb}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
156	}	150	}
157		151
158	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
159	# cannot destroy itself.	153	# cannot destroy itself.
160	my @destroy;	154	my @destroy;
…		…
166	while @destroy;	160	while @destroy;
167		161
168	&schedule;	162	&schedule;
169	}	163	}
170	};	164	};
171		165	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
173		167
174	# static methods. not really.
175
176	=back	168	=back
177		169
178	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
179
180	Static methods are actually functions that operate on the current coroutine only.
181		171
182	=over 4	172	=over 4
183		173
184	=item async { ... } [@args...]	174	=item async { ... } [@args...]
185		175
186	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
187	(usually unused). When the sub returns the new coroutine is automatically	177	unused). The coroutine will be put into the ready queue, so
		178	it will start running automatically on the next scheduler run.
		179
		180	The first argument is a codeblock/closure that should be executed in the
		181	coroutine. When it returns argument returns the coroutine is automatically
188	terminated.	182	terminated.
189		183
190	Calling C<exit> in a coroutine will not work correctly, so do not do that.	184	The remaining arguments are passed as arguments to the closure.
191		185
192	When the coroutine dies, the program will exit, just as in the main	186	See the C<Coro::State::new> constructor for info about the coroutine
193	program.	187	environment in which coroutines are executed.
194		188
		189	Calling C<exit> in a coroutine will do the same as calling exit outside
		190	the coroutine. Likewise, when the coroutine dies, the program will exit,
		191	just as it would in the main program.
		192
		193	If you do not want that, you can provide a default C<die> handler, or
		194	simply avoid dieing (by use of C<eval>).
		195
195	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
196	async {	198	async {
197	print "@_\n";	199	print "@_\n";
198	} 1,2,3,4;	200	} 1,2,3,4;
199		201
200	=cut	202	=cut
201		203
202	sub async(&@) {	204	sub async(&@) {
203	my $pid = new Coro @_;	205	my $coro = new Coro @_;
204	$pid->ready;	206	$coro->ready;
205	$pid	207	$coro
206	}	208	}
		209
		210	=item async_pool { ... } [@args...]
		211
		212	Similar to C<async>, but uses a coroutine pool, so you should not call
		213	terminate or join on it (although you are allowed to), and you get a
		214	coroutine that might have executed other code already (which can be good
		215	or bad :).
		216
		217	On the plus side, this function is faster than creating (and destroying)
		218	a completly new coroutine, so if you need a lot of generic coroutines in
		219	quick successsion, use C<async_pool>, not C<async>.
		220
		221	The code block is executed in an C<eval> context and a warning will be
		222	issued in case of an exception instead of terminating the program, as
		223	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		224	will not work in the expected way, unless you call terminate or cancel,
		225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
		227
		228	The priority will be reset to C<0> after each run, tracing will be
		229	disabled, the description will be reset and the default output filehandle
		230	gets restored, so you can change all these. Otherwise the coroutine will
		231	be re-used "as-is": most notably if you change other per-coroutine global
		232	stuff such as C<$/> you I<must needs> revert that change, which is most
		233	simply done by using local as in: C<< local $/ >>.
		234
		235	The idle pool size is limited to C<8> idle coroutines (this can be
		236	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
		237	coros as required.
		238
		239	If you are concerned about pooled coroutines growing a lot because a
		240	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		241	{ terminate }> once per second or so to slowly replenish the pool. In
		242	addition to that, when the stacks used by a handler grows larger than 16kb
		243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		244
		245	=cut
		246
		247	our $POOL_SIZE = 8;
		248	our $POOL_RSS = 16 * 1024;
		249	our @async_pool;
		250
		251	sub pool_handler {
		252	my $cb;
		253
		254	while () {
		255	eval {
		256	while () {
		257	_pool_1 $cb;
		258	&$cb;
		259	_pool_2 $cb;
		260	&schedule;
		261	}
		262	};
		263
		264	if ($@) {
		265	last if $@ eq "\3async_pool terminate\2\n";
		266	warn $@;
		267	}
		268	}
		269	}
		270
		271	sub async_pool(&@) {
		272	# this is also inlined into the unblock_scheduler
		273	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		274
		275	$coro->{_invoke} = [@_];
		276	$coro->ready;
		277
		278	$coro
		279	}
		280
		281	=back
		282
		283	=head2 STATIC METHODS
		284
		285	Static methods are actually functions that operate on the current coroutine.
		286
		287	=over 4
207		288
208	=item schedule	289	=item schedule
209		290
210	Calls the scheduler. Please note that the current coroutine will not be put	291	Calls the scheduler. The scheduler will find the next coroutine that is
		292	to be run from the ready queue and switches to it. The next coroutine
		293	to be run is simply the one with the highest priority that is longest
		294	in its ready queue. If there is no coroutine ready, it will clal the
		295	C<$Coro::idle> hook.
		296
		297	Please note that the current coroutine will I<not> be put into the ready
211	into the ready queue, so calling this function usually means you will	298	queue, so calling this function usually means you will never be called
212	never be called again unless something else (e.g. an event handler) calls	299	again unless something else (e.g. an event handler) calls C<< ->ready >>,
213	ready.	300	thus waking you up.
214		301
215	The canonical way to wait on external events is this:	302	This makes C<schedule> I<the> generic method to use to block the current
		303	coroutine and wait for events: first you remember the current coroutine in
		304	a variable, then arrange for some callback of yours to call C<< ->ready
		305	>> on that once some event happens, and last you call C<schedule> to put
		306	yourself to sleep. Note that a lot of things can wake your coroutine up,
		307	so you need to check whether the event indeed happened, e.g. by storing the
		308	status in a variable.
216		309
217	{	310	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
218	# remember current coroutine
219	my $current = $Coro::current;
220
221	# register a hypothetical event handler
222	on_event_invoke sub {
223	# wake up sleeping coroutine
224	$current->ready;
225	undef $current;
226	};
227
228	# call schedule until event occured.
229	# in case we are woken up for other reasons
230	# (current still defined), loop.
231	Coro::schedule while $current;
232	}
233		311
234	=item cede	312	=item cede
235		313
236	"Cede" to other coroutines. This function puts the current coroutine into the	314	"Cede" to other coroutines. This function puts the current coroutine into
237	ready queue and calls C<schedule>, which has the effect of giving up the	315	the ready queue and calls C<schedule>, which has the effect of giving
238	current "timeslice" to other coroutines of the same or higher priority.	316	up the current "timeslice" to other coroutines of the same or higher
		317	priority. Once your coroutine gets its turn again it will automatically be
		318	resumed.
		319
		320	This function is often called C<yield> in other languages.
239		321
240	=item Coro::cede_notself	322	=item Coro::cede_notself
241		323
242	Works like cede, but is not exported by default and will cede to any	324	Works like cede, but is not exported by default and will cede to I<any>
243	coroutine, regardless of priority, once.	325	coroutine, regardless of priority. This is useful sometimes to ensure
		326	progress is made.
244		327
245	=item terminate [arg...]	328	=item terminate [arg...]
246		329
247	Terminates the current coroutine with the given status values (see L<cancel>).	330	Terminates the current coroutine with the given status values (see L<cancel>).
		331
		332	=item killall
		333
		334	Kills/terminates/cancels all coroutines except the currently running
		335	one. This is useful after a fork, either in the child or the parent, as
		336	usually only one of them should inherit the running coroutines.
		337
		338	Note that while this will try to free some of the main programs resources,
		339	you cannot free all of them, so if a coroutine that is not the main
		340	program calls this function, there will be some one-time resource leak.
248		341
249	=cut	342	=cut
250		343
251	sub terminate {	344	sub terminate {
252	$current->cancel (@_);	345	$current->cancel (@_);
253	}	346	}
254		347
		348	sub killall {
		349	for (Coro::State::list) {
		350	$_->cancel
		351	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		352	}
		353	}
		354
255	=back	355	=back
256		356
257	# dynamic methods
258
259	=head2 COROUTINE METHODS	357	=head2 COROUTINE METHODS
260		358
261	These are the methods you can call on coroutine objects.	359	These are the methods you can call on coroutine objects (or to create
		360	them).
262		361
263	=over 4	362	=over 4
264		363
265	=item new Coro \&sub [, @args...]	364	=item new Coro \&sub [, @args...]
266		365
267	Create a new coroutine and return it. When the sub returns the coroutine	366	Create a new coroutine and return it. When the sub returns, the coroutine
268	automatically terminates as if C<terminate> with the returned values were	367	automatically terminates as if C<terminate> with the returned values were
269	called. To make the coroutine run you must first put it into the ready queue	368	called. To make the coroutine run you must first put it into the ready
270	by calling the ready method.	369	queue by calling the ready method.
271		370
272	Calling C<exit> in a coroutine will not work correctly, so do not do that.	371	See C<async> and C<Coro::State::new> for additional info about the
		372	coroutine environment.
273		373
274	=cut	374	=cut
275		375
276	sub _run_coro {	376	sub _terminate {
277	terminate &{+shift};	377	terminate &{+shift};
278	}	378	}
279		379
280	sub new {
281	my $class = shift;
282
283	$class->SUPER::new (\&_run_coro, @_)
284	}
285
286	=item $success = $coroutine->ready	380	=item $success = $coroutine->ready
287		381
288	Put the given coroutine into the ready queue (according to it's priority)	382	Put the given coroutine into the end of its ready queue (there is one
289	and return true. If the coroutine is already in the ready queue, do nothing	383	queue for each priority) and return true. If the coroutine is already in
290	and return false.	384	the ready queue, do nothing and return false.
		385
		386	This ensures that the scheduler will resume this coroutine automatically
		387	once all the coroutines of higher priority and all coroutines of the same
		388	priority that were put into the ready queue earlier have been resumed.
291		389
292	=item $is_ready = $coroutine->is_ready	390	=item $is_ready = $coroutine->is_ready
293		391
294	Return wether the coroutine is currently the ready queue or not,	392	Return whether the coroutine is currently the ready queue or not,
295		393
296	=item $coroutine->cancel (arg...)	394	=item $coroutine->cancel (arg...)
297		395
298	Terminates the given coroutine and makes it return the given arguments as	396	Terminates the given coroutine and makes it return the given arguments as
299	status (default: the empty list). Never returns if the coroutine is the	397	status (default: the empty list). Never returns if the coroutine is the
…		…
301		399
302	=cut	400	=cut
303		401
304	sub cancel {	402	sub cancel {
305	my $self = shift;	403	my $self = shift;
306	$self->{status} = [@_];	404	$self->{_status} = [@_];
307		405
308	if ($current == $self) {	406	if ($current == $self) {
309	push @destroy, $self;	407	push @destroy, $self;
310	$manager->ready;	408	$manager->ready;
311	&schedule while 1;	409	&schedule while 1;
312	} else {	410	} else {
313	$self->_cancel;	411	$self->_cancel;
314	}	412	}
315	}	413	}
316		414
		415	=item $coroutine->throw ([$scalar])
		416
		417	If C<$throw> is specified and defined, it will be thrown as an exception
		418	inside the coroutine at the next convenient point in time. Otherwise
		419	clears the exception object.
		420
		421	Coro will check for the exception each time a schedule-like-function
		422	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		423	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		424	detect this case and return early in case an exception is pending.
		425
		426	The exception object will be thrown "as is" with the specified scalar in
		427	C<$@>, i.e. if it is a string, no line number or newline will be appended
		428	(unlike with C<die>).
		429
		430	This can be used as a softer means than C<cancel> to ask a coroutine to
		431	end itself, although there is no guarantee that the exception will lead to
		432	termination, and if the exception isn't caught it might well end the whole
		433	program.
		434
		435	You might also think of C<throw> as being the moral equivalent of
		436	C<kill>ing a coroutine with a signal (in this case, a scalar).
		437
317	=item $coroutine->join	438	=item $coroutine->join
318		439
319	Wait until the coroutine terminates and return any values given to the	440	Wait until the coroutine terminates and return any values given to the
320	C<terminate> or C<cancel> functions. C<join> can be called multiple times	441	C<terminate> or C<cancel> functions. C<join> can be called concurrently
321	from multiple coroutine.	442	from multiple coroutines, and all will be resumed and given the status
		443	return once the C<$coroutine> terminates.
322		444
323	=cut	445	=cut
324		446
325	sub join {	447	sub join {
326	my $self = shift;	448	my $self = shift;
327		449
328	unless ($self->{status}) {	450	unless ($self->{_status}) {
329	my $current = $current;	451	my $current = $current;
330		452
331	push @{$self->{destroy_cb}}, sub {	453	push @{$self->{_on_destroy}}, sub {
332	$current->ready;	454	$current->ready;
333	undef $current;	455	undef $current;
334	};	456	};
335		457
336	&schedule while $current;	458	&schedule while $current;
337	}	459	}
338		460
339	wantarray ? @{$self->{status}} : $self->{status}[0];	461	wantarray ? @{$self->{_status}} : $self->{_status}[0];
340	}	462	}
341		463
342	=item $coroutine->on_destroy (\&cb)	464	=item $coroutine->on_destroy (\&cb)
343		465
344	Registers a callback that is called when this coroutine gets destroyed,	466	Registers a callback that is called when this coroutine gets destroyed,
345	but before it is joined. The callback gets passed the terminate arguments,	467	but before it is joined. The callback gets passed the terminate arguments,
346	if any.	468	if any, and I<must not> die, under any circumstances.
347		469
348	=cut	470	=cut
349		471
350	sub on_destroy {	472	sub on_destroy {
351	my ($self, $cb) = @_;	473	my ($self, $cb) = @_;
352		474
353	push @{ $self->{destroy_cb} }, $cb;	475	push @{ $self->{_on_destroy} }, $cb;
354	}	476	}
355		477
356	=item $oldprio = $coroutine->prio ($newprio)	478	=item $oldprio = $coroutine->prio ($newprio)
357		479
358	Sets (or gets, if the argument is missing) the priority of the	480	Sets (or gets, if the argument is missing) the priority of the
…		…
381	higher values mean lower priority, just as in unix).	503	higher values mean lower priority, just as in unix).
382		504
383	=item $olddesc = $coroutine->desc ($newdesc)	505	=item $olddesc = $coroutine->desc ($newdesc)
384		506
385	Sets (or gets in case the argument is missing) the description for this	507	Sets (or gets in case the argument is missing) the description for this
386	coroutine. This is just a free-form string you can associate with a coroutine.	508	coroutine. This is just a free-form string you can associate with a
		509	coroutine.
		510
		511	This method simply sets the C<< $coroutine->{desc} >> member to the given
		512	string. You can modify this member directly if you wish.
387		513
388	=cut	514	=cut
389		515
390	sub desc {	516	sub desc {
391	my $old = $_[0]{desc};	517	my $old = $_[0]{desc};
…		…
400	=over 4	526	=over 4
401		527
402	=item Coro::nready	528	=item Coro::nready
403		529
404	Returns the number of coroutines that are currently in the ready state,	530	Returns the number of coroutines that are currently in the ready state,
405	i.e. that can be swicthed to. The value C<0> means that the only runnable	531	i.e. that can be switched to by calling C<schedule> directory or
		532	indirectly. The value C<0> means that the only runnable coroutine is the
406	coroutine is the currently running one, so C<cede> would have no effect,	533	currently running one, so C<cede> would have no effect, and C<schedule>
407	and C<schedule> would cause a deadlock unless there is an idle handler	534	would cause a deadlock unless there is an idle handler that wakes up some
408	that wakes up some coroutines.	535	coroutines.
409		536
410	=item my $guard = Coro::guard { ... }	537	=item my $guard = Coro::guard { ... }
411		538
412	This creates and returns a guard object. Nothing happens until the objetc	539	This creates and returns a guard object. Nothing happens until the object
413	gets destroyed, in which case the codeblock given as argument will be	540	gets destroyed, in which case the codeblock given as argument will be
414	executed. This is useful to free locks or other resources in case of a	541	executed. This is useful to free locks or other resources in case of a
415	runtime error or when the coroutine gets canceled, as in both cases the	542	runtime error or when the coroutine gets canceled, as in both cases the
416	guard block will be executed. The guard object supports only one method,	543	guard block will be executed. The guard object supports only one method,
417	C<< ->cancel >>, which will keep the codeblock from being executed.	544	C<< ->cancel >>, which will keep the codeblock from being executed.
…		…
442		569
443		570
444	=item unblock_sub { ... }	571	=item unblock_sub { ... }
445		572
446	This utility function takes a BLOCK or code reference and "unblocks" it,	573	This utility function takes a BLOCK or code reference and "unblocks" it,
447	returning the new coderef. This means that the new coderef will return	574	returning a new coderef. Unblocking means that calling the new coderef
448	immediately without blocking, returning nothing, while the original code	575	will return immediately without blocking, returning nothing, while the
449	ref will be called (with parameters) from within its own coroutine.	576	original code ref will be called (with parameters) from within another
		577	coroutine.
450		578
451	The reason this fucntion exists is that many event libraries (such as the	579	The reason this function exists is that many event libraries (such as the
452	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	580	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
453	of thread-safety). This means you must not block within event callbacks,	581	of thread-safety). This means you must not block within event callbacks,
454	otherwise you might suffer from crashes or worse.	582	otherwise you might suffer from crashes or worse. The only event library
		583	currently known that is safe to use without C<unblock_sub> is L<EV>.
455		584
456	This function allows your callbacks to block by executing them in another	585	This function allows your callbacks to block by executing them in another
457	coroutine where it is safe to block. One example where blocking is handy	586	coroutine where it is safe to block. One example where blocking is handy
458	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	587	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
459	disk.	588	disk, for example.
460		589
461	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	590	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
462	creating event callbacks that want to block.	591	creating event callbacks that want to block.
463		592
464	=cut	593	If your handler does not plan to block (e.g. simply sends a message to
		594	another coroutine, or puts some other coroutine into the ready queue),
		595	there is no reason to use C<unblock_sub>.
465		596
466	our @unblock_pool;	597	Note that you also need to use C<unblock_sub> for any other callbacks that
		598	are indirectly executed by any C-based event loop. For example, when you
		599	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		600	provides callbacks that are the result of some event callback, then you
		601	must not block either, or use C<unblock_sub>.
		602
		603	=cut
		604
467	our @unblock_queue;	605	our @unblock_queue;
468	our $UNBLOCK_POOL_SIZE = 2;
469		606
470	sub unblock_handler_ {	607	# we create a special coro because we want to cede,
471	while () {	608	# to reduce pressure on the coro pool (because most callbacks
472	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	609	# return immediately and can be reused) and because we cannot cede
473	$cb->(@arg);	610	# inside an event callback.
474
475	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
476	push @unblock_pool, $Coro::current;
477	schedule;
478	}
479	}
480
481	our $unblock_scheduler = async {	611	our $unblock_scheduler = new Coro sub {
482	while () {	612	while () {
483	while (my $cb = pop @unblock_queue) {	613	while (my $cb = pop @unblock_queue) {
484	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	614	# this is an inlined copy of async_pool
485	$handler->{arg} = $cb;	615	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		616
		617	$coro->{_invoke} = $cb;
486	$handler->ready;	618	$coro->ready;
487	cede;	619	cede; # for short-lived callbacks, this reduces pressure on the coro pool
488	}	620	}
489		621	schedule; # sleep well
490	schedule;
491	}	622	}
492	};	623	};
		624	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
493		625
494	sub unblock_sub(&) {	626	sub unblock_sub(&) {
495	my $cb = shift;	627	my $cb = shift;
496		628
497	sub {	629	sub {
498	push @unblock_queue, [$cb, @_];	630	unshift @unblock_queue, [$cb, @_];
499	$unblock_scheduler->ready;	631	$unblock_scheduler->ready;
500	}	632	}
501	}	633	}
502		634
		635	=item $cb = Coro::rouse_cb
		636
		637	Create and return a "rouse callback". That's a code reference that, when
		638	called, will save its arguments and notify the owner coroutine of the
		639	callback.
		640
		641	See the next function.
		642
		643	=item @args = Coro::rouse_wait [$cb]
		644
		645	Wait for the specified rouse callback (or the last one tht was created in
		646	this coroutine).
		647
		648	As soon as the callback is invoked (or when the calback was invoked before
		649	C<rouse_wait>), it will return a copy of the arguments originally passed
		650	to the rouse callback.
		651
		652	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		653
503	=back	654	=back
504		655
505	=cut	656	=cut
506		657
507	1;	658	1;
508		659
		660	=head1 HOW TO WAIT FOR A CALLBACK
		661
		662	It is very common for a coroutine to wait for some callback to be
		663	called. This occurs naturally when you use coroutines in an otherwise
		664	event-based program, or when you use event-based libraries.
		665
		666	These typically register a callback for some event, and call that callback
		667	when the event occured. In a coroutine, however, you typically want to
		668	just wait for the event, simplyifying things.
		669
		670	For example C<< AnyEvent->child >> registers a callback to be called when
		671	a specific child has exited:
		672
		673	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		674
		675	But from withina coroutine, you often just want to write this:
		676
		677	my $status = wait_for_child $pid;
		678
		679	Coro offers two functions specifically designed to make this easy,
		680	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		681
		682	The first function, C<rouse_cb>, generates and returns a callback that,
		683	when invoked, will save it's arguments and notify the coroutine that
		684	created the callback.
		685
		686	The second function, C<rouse_wait>, waits for the callback to be called
		687	(by calling C<schedule> to go to sleep) and returns the arguments
		688	originally passed to the callback.
		689
		690	Using these functions, it becomes easy to write the C<wait_for_child>
		691	function mentioned above:
		692
		693	sub wait_for_child($) {
		694	my ($pid) = @_;
		695
		696	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		697
		698	my ($rpid, $rstatus) = Coro::rouse_wait;
		699	$rstatus
		700	}
		701
		702	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		703	you can roll your own, using C<schedule>:
		704
		705	sub wait_for_child($) {
		706	my ($pid) = @_;
		707
		708	# store the current coroutine in $current,
		709	# and provide result variables for the closure passed to ->child
		710	my $current = $Coro::current;
		711	my ($done, $rstatus);
		712
		713	# pass a closure to ->child
		714	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		715	$rstatus = $_[1]; # remember rstatus
		716	$done = 1; # mark $rstatus as valud
		717	});
		718
		719	# wait until the closure has been called
		720	schedule while !$done;
		721
		722	$rstatus
		723	}
		724
		725
509	=head1 BUGS/LIMITATIONS	726	=head1 BUGS/LIMITATIONS
510		727
511	- you must make very sure that no coro is still active on global	728	=over 4
512	destruction. very bad things might happen otherwise (usually segfaults).
513		729
		730	=item fork with pthread backend
		731
		732	When Coro is compiled using the pthread backend (which isn't recommended
		733	but required on many BSDs as their libcs are completely broken), then
		734	coroutines will not survive a fork. There is no known workaround except to
		735	fix your libc and use a saner backend.
		736
		737	=item perl process emulation ("threads")
		738
514	- this module is not thread-safe. You should only ever use this module	739	This module is not perl-pseudo-thread-safe. You should only ever use this
515	from the same thread (this requirement might be losened in the future	740	module from the same thread (this requirement might be removed in the
516	to allow per-thread schedulers, but Coro::State does not yet allow	741	future to allow per-thread schedulers, but Coro::State does not yet allow
517	this).	742	this). I recommend disabling thread support and using processes, as having
		743	the windows process emulation enabled under unix roughly halves perl
		744	performance, even when not used.
		745
		746	=item coroutine switching not signal safe
		747
		748	You must not switch to another coroutine from within a signal handler
		749	(only relevant with %SIG - most event libraries provide safe signals).
		750
		751	That means you I<MUST NOT> call any function that might "block" the
		752	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		753	anything that calls those. Everything else, including calling C<ready>,
		754	works.
		755
		756	=back
		757
518		758
519	=head1 SEE ALSO	759	=head1 SEE ALSO
520		760
		761	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		762
		763	Debugging: L<Coro::Debug>.
		764
521	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	765	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
522		766
523	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	767	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
524		768
525	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	769	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
526		770
527	Embedding: L<Coro:MakeMaker>	771	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		772
		773	XS API: L<Coro::MakeMaker>.
		774
		775	Low level Configuration, Coroutine Environment: L<Coro::State>.
528		776
529	=head1 AUTHOR	777	=head1 AUTHOR
530		778
531	Marc Lehmann <schmorp@schmorp.de>	779	Marc Lehmann <schmorp@schmorp.de>
532	http://home.schmorp.de/	780	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.103 by root, Thu Jan 4 20:14:19 2007 UTC vs. Revision 1.225 by root, Wed Nov 19 15:29:57 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.103 by root, Thu Jan 4 20:14:19 2007 UTC vs.
Revision 1.225 by root, Wed Nov 19 15:29:57 2008 UTC