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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.152 by root, Sun Oct 7 13:53:37 2007 UTC vs.
Revision 1.224 by root, Wed Nov 19 05:52:42 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";	11	print "2\n";
12	cede; # yield back to main	12	cede; # yield back to main
13	print "4\n";	13	print "4\n";
14	};	14	};
15	print "1\n";	15	print "1\n";
16	cede; # yield to coroutine	16	cede; # yield to coroutine
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
		21	use Coro::Semaphore;
21	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar	31	This module collection manages coroutines. Coroutines are similar to
31	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
32	machines. The specific flavor of coroutine used in this module also	33	on SMP machines. The specific flavor of coroutine used in this module
33	guarantees you that it will not switch between coroutines unless	34	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and	35	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much	36	parallel access are rarely an issue, making coroutine programming much
36	safer than threads programming.	37	safer and easier than threads programming.
37		38
38	(Perl, however, does not natively support real threads but instead does a	39	Unlike a normal perl program, however, coroutines allow you to have
39	very slow and memory-intensive emulation of processes using threads. This	40	multiple running interpreters that share data, which is especially useful
40	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).
41		51
42	In this module, coroutines are defined as "callchain + lexical variables +	52	In this module, coroutines are defined as "callchain + lexical variables +
43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
44	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
45	variables (see L<Coro::State> for more configuration).	55	variables (see L<Coro::State> for more configuration).
46		56
47	=cut	57	=cut
48		58
49	package Coro;	59	package Coro;
50		60
51	use strict;	61	use strict qw(vars subs);
52	no warnings "uninitialized";	62	no warnings "uninitialized";
53		63
54	use Coro::State;	64	use Coro::State;
55		65
56	use base qw(Coro::State Exporter);	66	use base qw(Coro::State Exporter);
57		67
58	our $idle; # idle handler	68	our $idle; # idle handler
59	our $main; # main coroutine	69	our $main; # main coroutine
60	our $current; # current coroutine	70	our $current; # current coroutine
61		71
62	our $VERSION = '4.1';	72	our $VERSION = 5.0;
63		73
64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
65	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
67	);	77	);
68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
69		79
70	{
71	my @async;
72	my $init;
73
74	# this way of handling attributes simply is NOT scalable ;()
75	sub import {
76	no strict 'refs';
77
78	Coro->export_to_level (1, @_);
79
80	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
81	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
82	my ($package, $ref) = (shift, shift);
83	my @attrs;
84	for (@_) {
85	if ($_ eq "Coro") {
86	push @async, $ref;
87	unless ($init++) {
88	eval q{
89	sub INIT {
90	&async(pop @async) while @async;
91	}
92	};
93	}
94	} else {
95	push @attrs, $_;
96	}
97	}
98	return $old ? $old->($package, $ref, @attrs) : @attrs;
99	};
100	}
101
102	}
103
104	=over 4	80	=over 4
105		81
106	=item $main	82	=item $Coro::main
107		83
108	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
109		88
110	=cut	89	=cut
111		90
112	$main = new Coro;	91	# $main is now being initialised by Coro::State
113		92
114	=item $current (or as function: current)	93	=item $Coro::current
115		94
116	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
117	is C<$main> (of course).	97	C<$Coro::main> (of course).
118		98
119	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
120	reasons. If performance is not essential you are encouraged to use the	100	value stored in it and use it as any other coroutine object, but you must
121	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
122		102
123	=cut	103	=cut
124		104
125	$main->{desc} = "[main::]";
126
127	# maybe some other module used Coro::Specific before...
128	$main->{_specific} = $current->{_specific}
129	if $current;
130
131	_set_current $main;
132
133	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
134		106
135	=item $idle	107	=item $Coro::idle
136		108
137	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
138	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
139	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.
140		117
141	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
142	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
143	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
		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.
144		129
145	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
146	handlers), then it must be prepared to be called recursively itself.	131	handlers), then it must be prepared to be called recursively itself.
147		132
148	=cut	133	=cut
…		…
159	$self->_destroy	144	$self->_destroy
160	or return;	145	or return;
161		146
162	# call all destruction callbacks	147	# call all destruction callbacks
163	$_->(@{$self->{_status}})	148	$_->(@{$self->{_status}})
164	for @{(delete $self->{_on_destroy}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
165	}	150	}
166		151
167	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
168	# cannot destroy itself.	153	# cannot destroy itself.
169	my @destroy;	154	my @destroy;
…		…
175	while @destroy;	160	while @destroy;
176		161
177	&schedule;	162	&schedule;
178	}	163	}
179	};	164	};
180	$manager->desc ("[coro manager]");	165	$manager->{desc} = "[coro manager]";
181	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
182		167
183	# static methods. not really.
184
185	=back	168	=back
186		169
187	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
188
189	Static methods are actually functions that operate on the current coroutine only.
190		171
191	=over 4	172	=over 4
192		173
193	=item async { ... } [@args...]	174	=item async { ... } [@args...]
194		175
195	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
196	(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
197	terminated.	182	terminated.
198		183
		184	The remaining arguments are passed as arguments to the closure.
		185
199	See the C<Coro::State::new> constructor for info about the coroutine	186	See the C<Coro::State::new> constructor for info about the coroutine
200	environment in which coroutines run.	187	environment in which coroutines are executed.
201		188
202	Calling C<exit> in a coroutine will do the same as calling exit outside	189	Calling C<exit> in a coroutine will do the same as calling exit outside
203	the coroutine. Likewise, when the coroutine dies, the program will exit,	190	the coroutine. Likewise, when the coroutine dies, the program will exit,
204	just as it would in the main program.	191	just as it would in the main program.
205		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
206	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
207	async {	198	async {
208	print "@_\n";	199	print "@_\n";
209	} 1,2,3,4;	200	} 1,2,3,4;
210		201
211	=cut	202	=cut
…		…
217	}	208	}
218		209
219	=item async_pool { ... } [@args...]	210	=item async_pool { ... } [@args...]
220		211
221	Similar to C<async>, but uses a coroutine pool, so you should not call	212	Similar to C<async>, but uses a coroutine pool, so you should not call
222	terminate or join (although you are allowed to), and you get a coroutine	213	terminate or join on it (although you are allowed to), and you get a
223	that might have executed other code already (which can be good or bad :).	214	coroutine that might have executed other code already (which can be good
		215	or bad :).
224		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
225	Also, the block is executed in an C<eval> context and a warning will be	221	The code block is executed in an C<eval> context and a warning will be
226	issued in case of an exception instead of terminating the program, as	222	issued in case of an exception instead of terminating the program, as
227	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	223	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
228	will not work in the expected way, unless you call terminate or cancel,	224	will not work in the expected way, unless you call terminate or cancel,
229	which somehow defeats the purpose of pooling.	225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
230		227
231	The priority will be reset to C<0> after each job, tracing will be	228	The priority will be reset to C<0> after each run, tracing will be
232	disabled, the description will be reset and the default output filehandle	229	disabled, the description will be reset and the default output filehandle
233	gets restored, so you can change alkl these. Otherwise the coroutine will	230	gets restored, so you can change all these. Otherwise the coroutine will
234	be re-used "as-is": most notably if you change other per-coroutine global	231	be re-used "as-is": most notably if you change other per-coroutine global
235	stuff such as C<$/> you need to revert that change, which is most simply	232	stuff such as C<$/> you I<must needs> revert that change, which is most
236	done by using local as in C< local $/ >.	233	simply done by using local as in: C<< local $/ >>.
237		234
238	The pool size is limited to 8 idle coroutines (this can be adjusted by	235	The idle pool size is limited to C<8> idle coroutines (this can be
239	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	236	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
240	required.	237	coros as required.
241		238
242	If you are concerned about pooled coroutines growing a lot because a	239	If you are concerned about pooled coroutines growing a lot because a
243	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	240	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
244	{ terminate }> once per second or so to slowly replenish the pool. In	241	{ terminate }> once per second or so to slowly replenish the pool. In
245	addition to that, when the stacks used by a handler grows larger than 16kb	242	addition to that, when the stacks used by a handler grows larger than 16kb
246	(adjustable with $Coro::POOL_RSS) it will also exit.	243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
247		244
248	=cut	245	=cut
249		246
250	our $POOL_SIZE = 8;	247	our $POOL_SIZE = 8;
251	our $POOL_RSS = 16 * 1024;	248	our $POOL_RSS = 16 * 1024;
…		…
262	_pool_2 $cb;	259	_pool_2 $cb;
263	&schedule;	260	&schedule;
264	}	261	}
265	};	262	};
266		263
		264	if ($@) {
267	last if $@ eq "\3async_pool terminate\2\n";	265	last if $@ eq "\3async_pool terminate\2\n";
268	warn $@ if $@;	266	warn $@;
		267	}
269	}	268	}
270	}	269	}
271		270
272	sub async_pool(&@) {	271	sub async_pool(&@) {
273	# this is also inlined into the unlock_scheduler	272	# this is also inlined into the unblock_scheduler
274	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;	273	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
275		274
276	$coro->{_invoke} = [@_];	275	$coro->{_invoke} = [@_];
277	$coro->ready;	276	$coro->ready;
278		277
279	$coro	278	$coro
280	}	279	}
281		280
		281	=back
		282
		283	=head2 STATIC METHODS
		284
		285	Static methods are actually functions that operate on the current coroutine.
		286
		287	=over 4
		288
282	=item schedule	289	=item schedule
283		290
284	Calls the scheduler. Please note that the current coroutine will not be put	291	Calls the scheduler. The scheduler will find the next coroutine that is
		292	to be run from the ready queue and switches to it. The next coroutine
		293	to be run is simply the one with the highest priority that is longest
		294	in its ready queue. If there is no coroutine ready, it will clal the
		295	C<$Coro::idle> hook.
		296
		297	Please note that the current coroutine will I<not> be put into the ready
285	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
286	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 >>,
287	ready.	300	thus waking you up.
288		301
289	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.
290		309
291	{	310	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
292	# remember current coroutine
293	my $current = $Coro::current;
294
295	# register a hypothetical event handler
296	on_event_invoke sub {
297	# wake up sleeping coroutine
298	$current->ready;
299	undef $current;
300	};
301
302	# call schedule until event occurred.
303	# in case we are woken up for other reasons
304	# (current still defined), loop.
305	Coro::schedule while $current;
306	}
307		311
308	=item cede	312	=item cede
309		313
310	"Cede" to other coroutines. This function puts the current coroutine into the	314	"Cede" to other coroutines. This function puts the current coroutine into
311	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
312	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.
313		319
314	Returns true if at least one coroutine switch has happened.	320	This function is often called C<yield> in other languages.
315		321
316	=item Coro::cede_notself	322	=item Coro::cede_notself
317		323
318	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>
319	coroutine, regardless of priority, once.	325	coroutine, regardless of priority. This is useful sometimes to ensure
320		326	progress is made.
321	Returns true if at least one coroutine switch has happened.
322		327
323	=item terminate [arg...]	328	=item terminate [arg...]
324		329
325	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>).
326		331
327	=item killall	332	=item killall
328		333
329	Kills/terminates/cancels all coroutines except the currently running	334	Kills/terminates/cancels all coroutines except the currently running
330	one. This is useful after a fork, either in the child or the parent, as	335	one. This is useful after a fork, either in the child or the parent, as
331	usually only one of them should inherit the running coroutines.	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.
332		341
333	=cut	342	=cut
334		343
335	sub terminate {	344	sub terminate {
336	$current->cancel (@_);	345	$current->cancel (@_);
…		…
343	}	352	}
344	}	353	}
345		354
346	=back	355	=back
347		356
348	# dynamic methods
349
350	=head2 COROUTINE METHODS	357	=head2 COROUTINE METHODS
351		358
352	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).
353		361
354	=over 4	362	=over 4
355		363
356	=item new Coro \&sub [, @args...]	364	=item new Coro \&sub [, @args...]
357		365
358	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
359	automatically terminates as if C<terminate> with the returned values were	367	automatically terminates as if C<terminate> with the returned values were
360	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
361	by calling the ready method.	369	queue by calling the ready method.
362		370
363	See C<async> and C<Coro::State::new> for additional info about the	371	See C<async> and C<Coro::State::new> for additional info about the
364	coroutine environment.	372	coroutine environment.
365		373
366	=cut	374	=cut
…		…
375	$class->SUPER::new (\&_run_coro, @_)	383	$class->SUPER::new (\&_run_coro, @_)
376	}	384	}
377		385
378	=item $success = $coroutine->ready	386	=item $success = $coroutine->ready
379		387
380	Put the given coroutine into the ready queue (according to it's priority)	388	Put the given coroutine into the end of its ready queue (there is one
381	and return true. If the coroutine is already in the ready queue, do nothing	389	queue for each priority) and return true. If the coroutine is already in
382	and return false.	390	the ready queue, do nothing and return false.
		391
		392	This ensures that the scheduler will resume this coroutine automatically
		393	once all the coroutines of higher priority and all coroutines of the same
		394	priority that were put into the ready queue earlier have been resumed.
383		395
384	=item $is_ready = $coroutine->is_ready	396	=item $is_ready = $coroutine->is_ready
385		397
386	Return wether the coroutine is currently the ready queue or not,	398	Return whether the coroutine is currently the ready queue or not,
387		399
388	=item $coroutine->cancel (arg...)	400	=item $coroutine->cancel (arg...)
389		401
390	Terminates the given coroutine and makes it return the given arguments as	402	Terminates the given coroutine and makes it return the given arguments as
391	status (default: the empty list). Never returns if the coroutine is the	403	status (default: the empty list). Never returns if the coroutine is the
…		…
404	} else {	416	} else {
405	$self->_cancel;	417	$self->_cancel;
406	}	418	}
407	}	419	}
408		420
		421	=item $coroutine->throw ([$scalar])
		422
		423	If C<$throw> is specified and defined, it will be thrown as an exception
		424	inside the coroutine at the next convenient point in time. Otherwise
		425	clears the exception object.
		426
		427	Coro will check for the exception each time a schedule-like-function
		428	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		429	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		430	detect this case and return early in case an exception is pending.
		431
		432	The exception object will be thrown "as is" with the specified scalar in
		433	C<$@>, i.e. if it is a string, no line number or newline will be appended
		434	(unlike with C<die>).
		435
		436	This can be used as a softer means than C<cancel> to ask a coroutine to
		437	end itself, although there is no guarantee that the exception will lead to
		438	termination, and if the exception isn't caught it might well end the whole
		439	program.
		440
		441	You might also think of C<throw> as being the moral equivalent of
		442	C<kill>ing a coroutine with a signal (in this case, a scalar).
		443
409	=item $coroutine->join	444	=item $coroutine->join
410		445
411	Wait until the coroutine terminates and return any values given to the	446	Wait until the coroutine terminates and return any values given to the
412	C<terminate> or C<cancel> functions. C<join> can be called concurrently	447	C<terminate> or C<cancel> functions. C<join> can be called concurrently
413	from multiple coroutines.	448	from multiple coroutines, and all will be resumed and given the status
		449	return once the C<$coroutine> terminates.
414		450
415	=cut	451	=cut
416		452
417	sub join {	453	sub join {
418	my $self = shift;	454	my $self = shift;
…		…
433		469
434	=item $coroutine->on_destroy (\&cb)	470	=item $coroutine->on_destroy (\&cb)
435		471
436	Registers a callback that is called when this coroutine gets destroyed,	472	Registers a callback that is called when this coroutine gets destroyed,
437	but before it is joined. The callback gets passed the terminate arguments,	473	but before it is joined. The callback gets passed the terminate arguments,
438	if any.	474	if any, and I<must not> die, under any circumstances.
439		475
440	=cut	476	=cut
441		477
442	sub on_destroy {	478	sub on_destroy {
443	my ($self, $cb) = @_;	479	my ($self, $cb) = @_;
…		…
473	higher values mean lower priority, just as in unix).	509	higher values mean lower priority, just as in unix).
474		510
475	=item $olddesc = $coroutine->desc ($newdesc)	511	=item $olddesc = $coroutine->desc ($newdesc)
476		512
477	Sets (or gets in case the argument is missing) the description for this	513	Sets (or gets in case the argument is missing) the description for this
478	coroutine. This is just a free-form string you can associate with a coroutine.	514	coroutine. This is just a free-form string you can associate with a
		515	coroutine.
479		516
480	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	517	This method simply sets the C<< $coroutine->{desc} >> member to the given
481	can modify this member directly if you wish.	518	string. You can modify this member directly if you wish.
482
483	=item $coroutine->throw ([$scalar])
484
485	If C<$throw> is specified and defined, it will be thrown as an exception
486	inside the coroutine at the next convinient point in time (usually after
487	it gains control at the next schedule/transfer/cede). Otherwise clears the
488	exception object.
489
490	The exception object will be thrown "as is" with the specified scalar in
491	C<$@>, i.e. if it is a string, no line number or newline will be appended
492	(unlike with C<die>).
493
494	This can be used as a softer means than C<cancel> to ask a coroutine to
495	end itself, although there is no guarentee that the exception will lead to
496	termination, and if the exception isn't caught it might well end the whole
497	program.
498		519
499	=cut	520	=cut
500		521
501	sub desc {	522	sub desc {
502	my $old = $_[0]{desc};	523	my $old = $_[0]{desc};
…		…
511	=over 4	532	=over 4
512		533
513	=item Coro::nready	534	=item Coro::nready
514		535
515	Returns the number of coroutines that are currently in the ready state,	536	Returns the number of coroutines that are currently in the ready state,
516	i.e. that can be switched to. The value C<0> means that the only runnable	537	i.e. that can be switched to by calling C<schedule> directory or
		538	indirectly. The value C<0> means that the only runnable coroutine is the
517	coroutine is the currently running one, so C<cede> would have no effect,	539	currently running one, so C<cede> would have no effect, and C<schedule>
518	and C<schedule> would cause a deadlock unless there is an idle handler	540	would cause a deadlock unless there is an idle handler that wakes up some
519	that wakes up some coroutines.	541	coroutines.
520		542
521	=item my $guard = Coro::guard { ... }	543	=item my $guard = Coro::guard { ... }
522		544
523	This creates and returns a guard object. Nothing happens until the object	545	This creates and returns a guard object. Nothing happens until the object
524	gets destroyed, in which case the codeblock given as argument will be	546	gets destroyed, in which case the codeblock given as argument will be
…		…
553		575
554		576
555	=item unblock_sub { ... }	577	=item unblock_sub { ... }
556		578
557	This utility function takes a BLOCK or code reference and "unblocks" it,	579	This utility function takes a BLOCK or code reference and "unblocks" it,
558	returning the new coderef. This means that the new coderef will return	580	returning a new coderef. Unblocking means that calling the new coderef
559	immediately without blocking, returning nothing, while the original code	581	will return immediately without blocking, returning nothing, while the
560	ref will be called (with parameters) from within its own coroutine.	582	original code ref will be called (with parameters) from within another
		583	coroutine.
561		584
562	The reason this function exists is that many event libraries (such as the	585	The reason this function exists is that many event libraries (such as the
563	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	586	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
564	of thread-safety). This means you must not block within event callbacks,	587	of thread-safety). This means you must not block within event callbacks,
565	otherwise you might suffer from crashes or worse.	588	otherwise you might suffer from crashes or worse. The only event library
		589	currently known that is safe to use without C<unblock_sub> is L<EV>.
566		590
567	This function allows your callbacks to block by executing them in another	591	This function allows your callbacks to block by executing them in another
568	coroutine where it is safe to block. One example where blocking is handy	592	coroutine where it is safe to block. One example where blocking is handy
569	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	593	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
570	disk.	594	disk, for example.
571		595
572	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	596	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
573	creating event callbacks that want to block.	597	creating event callbacks that want to block.
		598
		599	If your handler does not plan to block (e.g. simply sends a message to
		600	another coroutine, or puts some other coroutine into the ready queue),
		601	there is no reason to use C<unblock_sub>.
		602
		603	Note that you also need to use C<unblock_sub> for any other callbacks that
		604	are indirectly executed by any C-based event loop. For example, when you
		605	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		606	provides callbacks that are the result of some event callback, then you
		607	must not block either, or use C<unblock_sub>.
574		608
575	=cut	609	=cut
576		610
577	our @unblock_queue;	611	our @unblock_queue;
578		612
…		…
591	cede; # for short-lived callbacks, this reduces pressure on the coro pool	625	cede; # for short-lived callbacks, this reduces pressure on the coro pool
592	}	626	}
593	schedule; # sleep well	627	schedule; # sleep well
594	}	628	}
595	};	629	};
596	$unblock_scheduler->desc ("[unblock_sub scheduler]");	630	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
597		631
598	sub unblock_sub(&) {	632	sub unblock_sub(&) {
599	my $cb = shift;	633	my $cb = shift;
600		634
601	sub {	635	sub {
602	unshift @unblock_queue, [$cb, @_];	636	unshift @unblock_queue, [$cb, @_];
603	$unblock_scheduler->ready;	637	$unblock_scheduler->ready;
604	}	638	}
605	}	639	}
606		640
		641	=item $cb = Coro::rouse_cb
		642
		643	Create and return a "rouse callback". That's a code reference that, when
		644	called, will save its arguments and notify the owner coroutine of the
		645	callback.
		646
		647	See the next function.
		648
		649	=item @args = Coro::rouse_wait [$cb]
		650
		651	Wait for the specified rouse callback (or the last one tht was created in
		652	this coroutine).
		653
		654	As soon as the callback is invoked (or when the calback was invoked before
		655	C<rouse_wait>), it will return a copy of the arguments originally passed
		656	to the rouse callback.
		657
		658	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		659
607	=back	660	=back
608		661
609	=cut	662	=cut
610		663
611	1;	664	1;
612		665
		666	=head1 HOW TO WAIT FOR A CALLBACK
		667
		668	It is very common for a coroutine to wait for some callback to be
		669	called. This occurs naturally when you use coroutines in an otherwise
		670	event-based program, or when you use event-based libraries.
		671
		672	These typically register a callback for some event, and call that callback
		673	when the event occured. In a coroutine, however, you typically want to
		674	just wait for the event, simplyifying things.
		675
		676	For example C<< AnyEvent->child >> registers a callback to be called when
		677	a specific child has exited:
		678
		679	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		680
		681	But from withina coroutine, you often just want to write this:
		682
		683	my $status = wait_for_child $pid;
		684
		685	Coro offers two functions specifically designed to make this easy,
		686	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		687
		688	The first function, C<rouse_cb>, generates and returns a callback that,
		689	when invoked, will save it's arguments and notify the coroutine that
		690	created the callback.
		691
		692	The second function, C<rouse_wait>, waits for the callback to be called
		693	(by calling C<schedule> to go to sleep) and returns the arguments
		694	originally passed to the callback.
		695
		696	Using these functions, it becomes easy to write the C<wait_for_child>
		697	function mentioned above:
		698
		699	sub wait_for_child($) {
		700	my ($pid) = @_;
		701
		702	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		703
		704	my ($rpid, $rstatus) = Coro::rouse_wait;
		705	$rstatus
		706	}
		707
		708	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		709	you can roll your own, using C<schedule>:
		710
		711	sub wait_for_child($) {
		712	my ($pid) = @_;
		713
		714	# store the current coroutine in $current,
		715	# and provide result variables for the closure passed to ->child
		716	my $current = $Coro::current;
		717	my ($done, $rstatus);
		718
		719	# pass a closure to ->child
		720	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		721	$rstatus = $_[1]; # remember rstatus
		722	$done = 1; # mark $rstatus as valud
		723	});
		724
		725	# wait until the closure has been called
		726	schedule while !$done;
		727
		728	$rstatus
		729	}
		730
		731
613	=head1 BUGS/LIMITATIONS	732	=head1 BUGS/LIMITATIONS
614		733
615	- you must make very sure that no coro is still active on global	734	=over 4
616	destruction. very bad things might happen otherwise (usually segfaults).
617		735
		736	=item fork with pthread backend
		737
		738	When Coro is compiled using the pthread backend (which isn't recommended
		739	but required on many BSDs as their libcs are completely broken), then
		740	coroutines will not survive a fork. There is no known workaround except to
		741	fix your libc and use a saner backend.
		742
		743	=item perl process emulation ("threads")
		744
618	- this module is not thread-safe. You should only ever use this module	745	This module is not perl-pseudo-thread-safe. You should only ever use this
619	from the same thread (this requirement might be loosened in the future	746	module from the same thread (this requirement might be removed in the
620	to allow per-thread schedulers, but Coro::State does not yet allow	747	future to allow per-thread schedulers, but Coro::State does not yet allow
621	this).	748	this). I recommend disabling thread support and using processes, as having
		749	the windows process emulation enabled under unix roughly halves perl
		750	performance, even when not used.
		751
		752	=item coroutine switching not signal safe
		753
		754	You must not switch to another coroutine from within a signal handler
		755	(only relevant with %SIG - most event libraries provide safe signals).
		756
		757	That means you I<MUST NOT> call any function that might "block" the
		758	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		759	anything that calls those. Everything else, including calling C<ready>,
		760	works.
		761
		762	=back
		763
622		764
623	=head1 SEE ALSO	765	=head1 SEE ALSO
624		766
625	Lower level Configuration, Coroutine Environment: L<Coro::State>.	767	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
626		768
627	Debugging: L<Coro::Debug>.	769	Debugging: L<Coro::Debug>.
628		770
629	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	771	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
630		772
631	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	773	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
632		774
633	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	775	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
634		776
635	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	777	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
636		778
637	Embedding: L<Coro:MakeMaker>.	779	XS API: L<Coro::MakeMaker>.
		780
		781	Low level Configuration, Coroutine Environment: L<Coro::State>.
638		782
639	=head1 AUTHOR	783	=head1 AUTHOR
640		784
641	Marc Lehmann <schmorp@schmorp.de>	785	Marc Lehmann <schmorp@schmorp.de>
642	http://home.schmorp.de/	786	http://home.schmorp.de/

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.152 by root, Sun Oct 7 13:53:37 2007 UTC vs. Revision 1.224 by root, Wed Nov 19 05:52:42 2008 UTC

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Revision 1.224 by root, Wed Nov 19 05:52:42 2008 UTC