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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs.
Revision 1.230 by root, Thu Nov 20 07:02:43 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 = '4.51';	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
…		…
150	$idle = sub {	135	$idle = sub {
151	require Carp;	136	require Carp;
152	Carp::croak ("FATAL: deadlock detected");	137	Carp::croak ("FATAL: deadlock detected");
153	};	138	};
154		139
155	sub _cancel {
156	my ($self) = @_;
157
158	# free coroutine data and mark as destructed
159	$self->_destroy
160	or return;
161
162	# call all destruction callbacks
163	$_->(@{$self->{_status}})
164	for @{(delete $self->{_on_destroy}) \|\| []};
165	}
166
167	# this coroutine is necessary because a coroutine	140	# this coroutine is necessary because a coroutine
168	# cannot destroy itself.	141	# cannot destroy itself.
169	my @destroy;	142	our @destroy;
170	my $manager;	143	our $manager;
171		144
172	$manager = new Coro sub {	145	$manager = new Coro sub {
173	while () {	146	while () {
174	(shift @destroy)->_cancel	147	Coro::_cancel shift @destroy
175	while @destroy;	148	while @destroy;
176		149
177	&schedule;	150	&schedule;
178	}	151	}
179	};	152	};
180	$manager->desc ("[coro manager]");	153	$manager->{desc} = "[coro manager]";
181	$manager->prio (PRIO_MAX);	154	$manager->prio (PRIO_MAX);
182		155
183	=back	156	=back
184		157
185	=head2 STATIC METHODS	158	=head2 SIMPLE COROUTINE CREATION
186
187	Static methods are actually functions that operate on the current coroutine only.
188		159
189	=over 4	160	=over 4
190		161
191	=item async { ... } [@args...]	162	=item async { ... } [@args...]
192		163
193	Create a new asynchronous coroutine and return it's coroutine object	164	Create a new coroutine and return it's coroutine object (usually
194	(usually unused). When the sub returns the new coroutine is automatically	165	unused). The coroutine will be put into the ready queue, so
		166	it will start running automatically on the next scheduler run.
		167
		168	The first argument is a codeblock/closure that should be executed in the
		169	coroutine. When it returns argument returns the coroutine is automatically
195	terminated.	170	terminated.
196		171
		172	The remaining arguments are passed as arguments to the closure.
		173
197	See the C<Coro::State::new> constructor for info about the coroutine	174	See the C<Coro::State::new> constructor for info about the coroutine
198	environment in which coroutines run.	175	environment in which coroutines are executed.
199		176
200	Calling C<exit> in a coroutine will do the same as calling exit outside	177	Calling C<exit> in a coroutine will do the same as calling exit outside
201	the coroutine. Likewise, when the coroutine dies, the program will exit,	178	the coroutine. Likewise, when the coroutine dies, the program will exit,
202	just as it would in the main program.	179	just as it would in the main program.
203		180
		181	If you do not want that, you can provide a default C<die> handler, or
		182	simply avoid dieing (by use of C<eval>).
		183
204	# create a new coroutine that just prints its arguments	184	Example: Create a new coroutine that just prints its arguments.
		185
205	async {	186	async {
206	print "@_\n";	187	print "@_\n";
207	} 1,2,3,4;	188	} 1,2,3,4;
208		189
209	=cut	190	=cut
…		…
215	}	196	}
216		197
217	=item async_pool { ... } [@args...]	198	=item async_pool { ... } [@args...]
218		199
219	Similar to C<async>, but uses a coroutine pool, so you should not call	200	Similar to C<async>, but uses a coroutine pool, so you should not call
220	terminate or join (although you are allowed to), and you get a coroutine	201	terminate or join on it (although you are allowed to), and you get a
221	that might have executed other code already (which can be good or bad :).	202	coroutine that might have executed other code already (which can be good
		203	or bad :).
222		204
		205	On the plus side, this function is about twice as fast as creating (and
		206	destroying) a completely new coroutine, so if you need a lot of generic
		207	coroutines in quick successsion, use C<async_pool>, not C<async>.
		208
223	Also, the block is executed in an C<eval> context and a warning will be	209	The code block is executed in an C<eval> context and a warning will be
224	issued in case of an exception instead of terminating the program, as	210	issued in case of an exception instead of terminating the program, as
225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	211	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
226	will not work in the expected way, unless you call terminate or cancel,	212	will not work in the expected way, unless you call terminate or cancel,
227	which somehow defeats the purpose of pooling.	213	which somehow defeats the purpose of pooling (but is fine in the
		214	exceptional case).
228		215
229	The priority will be reset to C<0> after each job, tracing will be	216	The priority will be reset to C<0> after each run, tracing will be
230	disabled, the description will be reset and the default output filehandle	217	disabled, the description will be reset and the default output filehandle
231	gets restored, so you can change alkl these. Otherwise the coroutine will	218	gets restored, so you can change all these. Otherwise the coroutine will
232	be re-used "as-is": most notably if you change other per-coroutine global	219	be re-used "as-is": most notably if you change other per-coroutine global
233	stuff such as C<$/> you need to revert that change, which is most simply	220	stuff such as C<$/> you I<must needs> revert that change, which is most
234	done by using local as in C< local $/ >.	221	simply done by using local as in: C<< local $/ >>.
235		222
236	The pool size is limited to 8 idle coroutines (this can be adjusted by	223	The idle pool size is limited to C<8> idle coroutines (this can be
237	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	224	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
238	required.	225	coros as required.
239		226
240	If you are concerned about pooled coroutines growing a lot because a	227	If you are concerned about pooled coroutines growing a lot because a
241	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	228	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
242	{ terminate }> once per second or so to slowly replenish the pool. In	229	{ terminate }> once per second or so to slowly replenish the pool. In
243	addition to that, when the stacks used by a handler grows larger than 16kb	230	addition to that, when the stacks used by a handler grows larger than 16kb
244	(adjustable with $Coro::POOL_RSS) it will also exit.	231	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
245		232
246	=cut	233	=cut
247		234
248	our $POOL_SIZE = 8;	235	our $POOL_SIZE = 8;
249	our $POOL_RSS = 16 * 1024;	236	our $POOL_RSS = 16 * 1024;
250	our @async_pool;	237	our @async_pool;
251		238
252	sub pool_handler {	239	sub pool_handler {
253	my $cb;
254
255	while () {	240	while () {
256	eval {	241	eval {
257	while () {	242	&{&_pool_handler} while 1;
258	_pool_1 $cb;
259	&$cb;
260	_pool_2 $cb;
261	&schedule;
262	}
263	};	243	};
264		244
265	last if $@ eq "\3async_pool terminate\2\n";
266	warn $@ if $@;	245	warn $@ if $@;
267	}	246	}
268	}	247	}
269		248
270	sub async_pool(&@) {	249	=back
271	# this is also inlined into the unlock_scheduler
272	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
273		250
274	$coro->{_invoke} = [@_];	251	=head2 STATIC METHODS
275	$coro->ready;
276		252
277	$coro	253	Static methods are actually functions that operate on the current coroutine.
278	}	254
		255	=over 4
279		256
280	=item schedule	257	=item schedule
281		258
282	Calls the scheduler. Please note that the current coroutine will not be put	259	Calls the scheduler. The scheduler will find the next coroutine that is
		260	to be run from the ready queue and switches to it. The next coroutine
		261	to be run is simply the one with the highest priority that is longest
		262	in its ready queue. If there is no coroutine ready, it will clal the
		263	C<$Coro::idle> hook.
		264
		265	Please note that the current coroutine will I<not> be put into the ready
283	into the ready queue, so calling this function usually means you will	266	queue, so calling this function usually means you will never be called
284	never be called again unless something else (e.g. an event handler) calls	267	again unless something else (e.g. an event handler) calls C<< ->ready >>,
285	ready.	268	thus waking you up.
286		269
287	The canonical way to wait on external events is this:	270	This makes C<schedule> I<the> generic method to use to block the current
		271	coroutine and wait for events: first you remember the current coroutine in
		272	a variable, then arrange for some callback of yours to call C<< ->ready
		273	>> on that once some event happens, and last you call C<schedule> to put
		274	yourself to sleep. Note that a lot of things can wake your coroutine up,
		275	so you need to check whether the event indeed happened, e.g. by storing the
		276	status in a variable.
288		277
289	{	278	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
290	# remember current coroutine
291	my $current = $Coro::current;
292
293	# register a hypothetical event handler
294	on_event_invoke sub {
295	# wake up sleeping coroutine
296	$current->ready;
297	undef $current;
298	};
299
300	# call schedule until event occurred.
301	# in case we are woken up for other reasons
302	# (current still defined), loop.
303	Coro::schedule while $current;
304	}
305		279
306	=item cede	280	=item cede
307		281
308	"Cede" to other coroutines. This function puts the current coroutine into the	282	"Cede" to other coroutines. This function puts the current coroutine into
309	ready queue and calls C<schedule>, which has the effect of giving up the	283	the ready queue and calls C<schedule>, which has the effect of giving
310	current "timeslice" to other coroutines of the same or higher priority.	284	up the current "timeslice" to other coroutines of the same or higher
		285	priority. Once your coroutine gets its turn again it will automatically be
		286	resumed.
		287
		288	This function is often called C<yield> in other languages.
311		289
312	=item Coro::cede_notself	290	=item Coro::cede_notself
313		291
314	Works like cede, but is not exported by default and will cede to any	292	Works like cede, but is not exported by default and will cede to I<any>
315	coroutine, regardless of priority, once.	293	coroutine, regardless of priority. This is useful sometimes to ensure
		294	progress is made.
316		295
317	=item terminate [arg...]	296	=item terminate [arg...]
318		297
319	Terminates the current coroutine with the given status values (see L<cancel>).	298	Terminates the current coroutine with the given status values (see L<cancel>).
320		299
…		…
322		301
323	Kills/terminates/cancels all coroutines except the currently running	302	Kills/terminates/cancels all coroutines except the currently running
324	one. This is useful after a fork, either in the child or the parent, as	303	one. This is useful after a fork, either in the child or the parent, as
325	usually only one of them should inherit the running coroutines.	304	usually only one of them should inherit the running coroutines.
326		305
327	=cut	306	Note that while this will try to free some of the main programs resources,
		307	you cannot free all of them, so if a coroutine that is not the main
		308	program calls this function, there will be some one-time resource leak.
328		309
329	sub terminate {	310	=cut
330	$current->cancel (@_);
331	}
332		311
333	sub killall {	312	sub killall {
334	for (Coro::State::list) {	313	for (Coro::State::list) {
335	$_->cancel	314	$_->cancel
336	if $_ != $current && UNIVERSAL::isa $_, "Coro";	315	if $_ != $current && UNIVERSAL::isa $_, "Coro";
…		…
339		318
340	=back	319	=back
341		320
342	=head2 COROUTINE METHODS	321	=head2 COROUTINE METHODS
343		322
344	These are the methods you can call on coroutine objects.	323	These are the methods you can call on coroutine objects (or to create
		324	them).
345		325
346	=over 4	326	=over 4
347		327
348	=item new Coro \&sub [, @args...]	328	=item new Coro \&sub [, @args...]
349		329
350	Create a new coroutine and return it. When the sub returns the coroutine	330	Create a new coroutine and return it. When the sub returns, the coroutine
351	automatically terminates as if C<terminate> with the returned values were	331	automatically terminates as if C<terminate> with the returned values were
352	called. To make the coroutine run you must first put it into the ready queue	332	called. To make the coroutine run you must first put it into the ready
353	by calling the ready method.	333	queue by calling the ready method.
354		334
355	See C<async> and C<Coro::State::new> for additional info about the	335	See C<async> and C<Coro::State::new> for additional info about the
356	coroutine environment.	336	coroutine environment.
357		337
358	=cut	338	=cut
359		339
360	sub _run_coro {	340	sub _terminate {
361	terminate &{+shift};	341	terminate &{+shift};
362	}	342	}
363		343
364	sub new {
365	my $class = shift;
366
367	$class->SUPER::new (\&_run_coro, @_)
368	}
369
370	=item $success = $coroutine->ready	344	=item $success = $coroutine->ready
371		345
372	Put the given coroutine into the ready queue (according to it's priority)	346	Put the given coroutine into the end of its ready queue (there is one
373	and return true. If the coroutine is already in the ready queue, do nothing	347	queue for each priority) and return true. If the coroutine is already in
374	and return false.	348	the ready queue, do nothing and return false.
		349
		350	This ensures that the scheduler will resume this coroutine automatically
		351	once all the coroutines of higher priority and all coroutines of the same
		352	priority that were put into the ready queue earlier have been resumed.
375		353
376	=item $is_ready = $coroutine->is_ready	354	=item $is_ready = $coroutine->is_ready
377		355
378	Return wether the coroutine is currently the ready queue or not,	356	Return whether the coroutine is currently the ready queue or not,
379		357
380	=item $coroutine->cancel (arg...)	358	=item $coroutine->cancel (arg...)
381		359
382	Terminates the given coroutine and makes it return the given arguments as	360	Terminates the given coroutine and makes it return the given arguments as
383	status (default: the empty list). Never returns if the coroutine is the	361	status (default: the empty list). Never returns if the coroutine is the
…		…
385		363
386	=cut	364	=cut
387		365
388	sub cancel {	366	sub cancel {
389	my $self = shift;	367	my $self = shift;
390	$self->{_status} = [@_];
391		368
392	if ($current == $self) {	369	if ($current == $self) {
393	push @destroy, $self;	370	terminate @_;
394	$manager->ready;
395	&schedule while 1;
396	} else {	371	} else {
		372	$self->{_status} = [@_];
397	$self->_cancel;	373	$self->_cancel;
398	}	374	}
399	}	375	}
		376
		377	=item $coroutine->schedule_to
		378
		379	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		380	of continuing with the next coro from the ready queue, always switch to
		381	the given coroutine object (regardless of priority etc.). The readyness
		382	state of that coroutine isn't changed.
		383
		384	This is an advanced method for special cases - I'd love to hear about any
		385	uses for this one.
		386
		387	=item $coroutine->cede_to
		388
		389	Like C<schedule_to>, but puts the current coroutine into the ready
		390	queue. This has the effect of temporarily switching to the given
		391	coroutine, and continuing some time later.
		392
		393	This is an advanced method for special cases - I'd love to hear about any
		394	uses for this one.
		395
		396	=item $coroutine->throw ([$scalar])
		397
		398	If C<$throw> is specified and defined, it will be thrown as an exception
		399	inside the coroutine at the next convenient point in time. Otherwise
		400	clears the exception object.
		401
		402	Coro will check for the exception each time a schedule-like-function
		403	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		404	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		405	detect this case and return early in case an exception is pending.
		406
		407	The exception object will be thrown "as is" with the specified scalar in
		408	C<$@>, i.e. if it is a string, no line number or newline will be appended
		409	(unlike with C<die>).
		410
		411	This can be used as a softer means than C<cancel> to ask a coroutine to
		412	end itself, although there is no guarantee that the exception will lead to
		413	termination, and if the exception isn't caught it might well end the whole
		414	program.
		415
		416	You might also think of C<throw> as being the moral equivalent of
		417	C<kill>ing a coroutine with a signal (in this case, a scalar).
400		418
401	=item $coroutine->join	419	=item $coroutine->join
402		420
403	Wait until the coroutine terminates and return any values given to the	421	Wait until the coroutine terminates and return any values given to the
404	C<terminate> or C<cancel> functions. C<join> can be called concurrently	422	C<terminate> or C<cancel> functions. C<join> can be called concurrently
405	from multiple coroutines.	423	from multiple coroutines, and all will be resumed and given the status
		424	return once the C<$coroutine> terminates.
406		425
407	=cut	426	=cut
408		427
409	sub join {	428	sub join {
410	my $self = shift;	429	my $self = shift;
…		…
425		444
426	=item $coroutine->on_destroy (\&cb)	445	=item $coroutine->on_destroy (\&cb)
427		446
428	Registers a callback that is called when this coroutine gets destroyed,	447	Registers a callback that is called when this coroutine gets destroyed,
429	but before it is joined. The callback gets passed the terminate arguments,	448	but before it is joined. The callback gets passed the terminate arguments,
430	if any.	449	if any, and I<must not> die, under any circumstances.
431		450
432	=cut	451	=cut
433		452
434	sub on_destroy {	453	sub on_destroy {
435	my ($self, $cb) = @_;	454	my ($self, $cb) = @_;
…		…
465	higher values mean lower priority, just as in unix).	484	higher values mean lower priority, just as in unix).
466		485
467	=item $olddesc = $coroutine->desc ($newdesc)	486	=item $olddesc = $coroutine->desc ($newdesc)
468		487
469	Sets (or gets in case the argument is missing) the description for this	488	Sets (or gets in case the argument is missing) the description for this
470	coroutine. This is just a free-form string you can associate with a coroutine.	489	coroutine. This is just a free-form string you can associate with a
		490	coroutine.
471		491
472	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	492	This method simply sets the C<< $coroutine->{desc} >> member to the given
473	can modify this member directly if you wish.	493	string. You can modify this member directly if you wish.
474
475	=item $coroutine->throw ([$scalar])
476
477	If C<$throw> is specified and defined, it will be thrown as an exception
478	inside the coroutine at the next convinient point in time (usually after
479	it gains control at the next schedule/transfer/cede). Otherwise clears the
480	exception object.
481
482	The exception object will be thrown "as is" with the specified scalar in
483	C<$@>, i.e. if it is a string, no line number or newline will be appended
484	(unlike with C<die>).
485
486	This can be used as a softer means than C<cancel> to ask a coroutine to
487	end itself, although there is no guarentee that the exception will lead to
488	termination, and if the exception isn't caught it might well end the whole
489	program.
490		494
491	=cut	495	=cut
492		496
493	sub desc {	497	sub desc {
494	my $old = $_[0]{desc};	498	my $old = $_[0]{desc};
…		…
503	=over 4	507	=over 4
504		508
505	=item Coro::nready	509	=item Coro::nready
506		510
507	Returns the number of coroutines that are currently in the ready state,	511	Returns the number of coroutines that are currently in the ready state,
508	i.e. that can be switched to. The value C<0> means that the only runnable	512	i.e. that can be switched to by calling C<schedule> directory or
		513	indirectly. The value C<0> means that the only runnable coroutine is the
509	coroutine is the currently running one, so C<cede> would have no effect,	514	currently running one, so C<cede> would have no effect, and C<schedule>
510	and C<schedule> would cause a deadlock unless there is an idle handler	515	would cause a deadlock unless there is an idle handler that wakes up some
511	that wakes up some coroutines.	516	coroutines.
512		517
513	=item my $guard = Coro::guard { ... }	518	=item my $guard = Coro::guard { ... }
514		519
515	This creates and returns a guard object. Nothing happens until the object	520	This creates and returns a guard object. Nothing happens until the object
516	gets destroyed, in which case the codeblock given as argument will be	521	gets destroyed, in which case the codeblock given as argument will be
…		…
545		550
546		551
547	=item unblock_sub { ... }	552	=item unblock_sub { ... }
548		553
549	This utility function takes a BLOCK or code reference and "unblocks" it,	554	This utility function takes a BLOCK or code reference and "unblocks" it,
550	returning the new coderef. This means that the new coderef will return	555	returning a new coderef. Unblocking means that calling the new coderef
551	immediately without blocking, returning nothing, while the original code	556	will return immediately without blocking, returning nothing, while the
552	ref will be called (with parameters) from within its own coroutine.	557	original code ref will be called (with parameters) from within another
		558	coroutine.
553		559
554	The reason this function exists is that many event libraries (such as the	560	The reason this function exists is that many event libraries (such as the
555	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	561	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
556	of thread-safety). This means you must not block within event callbacks,	562	of thread-safety). This means you must not block within event callbacks,
557	otherwise you might suffer from crashes or worse.	563	otherwise you might suffer from crashes or worse. The only event library
		564	currently known that is safe to use without C<unblock_sub> is L<EV>.
558		565
559	This function allows your callbacks to block by executing them in another	566	This function allows your callbacks to block by executing them in another
560	coroutine where it is safe to block. One example where blocking is handy	567	coroutine where it is safe to block. One example where blocking is handy
561	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	568	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
562	disk.	569	disk, for example.
563		570
564	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	571	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
565	creating event callbacks that want to block.	572	creating event callbacks that want to block.
		573
		574	If your handler does not plan to block (e.g. simply sends a message to
		575	another coroutine, or puts some other coroutine into the ready queue),
		576	there is no reason to use C<unblock_sub>.
		577
		578	Note that you also need to use C<unblock_sub> for any other callbacks that
		579	are indirectly executed by any C-based event loop. For example, when you
		580	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		581	provides callbacks that are the result of some event callback, then you
		582	must not block either, or use C<unblock_sub>.
566		583
567	=cut	584	=cut
568		585
569	our @unblock_queue;	586	our @unblock_queue;
570		587
…		…
573	# return immediately and can be reused) and because we cannot cede	590	# return immediately and can be reused) and because we cannot cede
574	# inside an event callback.	591	# inside an event callback.
575	our $unblock_scheduler = new Coro sub {	592	our $unblock_scheduler = new Coro sub {
576	while () {	593	while () {
577	while (my $cb = pop @unblock_queue) {	594	while (my $cb = pop @unblock_queue) {
578	# this is an inlined copy of async_pool	595	&async_pool (@$cb);
579	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
580		596
581	$coro->{_invoke} = $cb;
582	$coro->ready;
583	cede; # for short-lived callbacks, this reduces pressure on the coro pool	597	# for short-lived callbacks, this reduces pressure on the coro pool
		598	# as the chance is very high that the async_poll coro will be back
		599	# in the idle state when cede returns
		600	cede;
584	}	601	}
585	schedule; # sleep well	602	schedule; # sleep well
586	}	603	}
587	};	604	};
588	$unblock_scheduler->desc ("[unblock_sub scheduler]");	605	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
589		606
590	sub unblock_sub(&) {	607	sub unblock_sub(&) {
591	my $cb = shift;	608	my $cb = shift;
592		609
593	sub {	610	sub {
594	unshift @unblock_queue, [$cb, @_];	611	unshift @unblock_queue, [$cb, @_];
595	$unblock_scheduler->ready;	612	$unblock_scheduler->ready;
596	}	613	}
597	}	614	}
598		615
		616	=item $cb = Coro::rouse_cb
		617
		618	Create and return a "rouse callback". That's a code reference that, when
		619	called, will save its arguments and notify the owner coroutine of the
		620	callback.
		621
		622	See the next function.
		623
		624	=item @args = Coro::rouse_wait [$cb]
		625
		626	Wait for the specified rouse callback (or the last one tht was created in
		627	this coroutine).
		628
		629	As soon as the callback is invoked (or when the calback was invoked before
		630	C<rouse_wait>), it will return a copy of the arguments originally passed
		631	to the rouse callback.
		632
		633	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		634
599	=back	635	=back
600		636
601	=cut	637	=cut
602		638
603	1;	639	1;
604		640
		641	=head1 HOW TO WAIT FOR A CALLBACK
		642
		643	It is very common for a coroutine to wait for some callback to be
		644	called. This occurs naturally when you use coroutines in an otherwise
		645	event-based program, or when you use event-based libraries.
		646
		647	These typically register a callback for some event, and call that callback
		648	when the event occured. In a coroutine, however, you typically want to
		649	just wait for the event, simplyifying things.
		650
		651	For example C<< AnyEvent->child >> registers a callback to be called when
		652	a specific child has exited:
		653
		654	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		655
		656	But from withina coroutine, you often just want to write this:
		657
		658	my $status = wait_for_child $pid;
		659
		660	Coro offers two functions specifically designed to make this easy,
		661	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		662
		663	The first function, C<rouse_cb>, generates and returns a callback that,
		664	when invoked, will save it's arguments and notify the coroutine that
		665	created the callback.
		666
		667	The second function, C<rouse_wait>, waits for the callback to be called
		668	(by calling C<schedule> to go to sleep) and returns the arguments
		669	originally passed to the callback.
		670
		671	Using these functions, it becomes easy to write the C<wait_for_child>
		672	function mentioned above:
		673
		674	sub wait_for_child($) {
		675	my ($pid) = @_;
		676
		677	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		678
		679	my ($rpid, $rstatus) = Coro::rouse_wait;
		680	$rstatus
		681	}
		682
		683	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		684	you can roll your own, using C<schedule>:
		685
		686	sub wait_for_child($) {
		687	my ($pid) = @_;
		688
		689	# store the current coroutine in $current,
		690	# and provide result variables for the closure passed to ->child
		691	my $current = $Coro::current;
		692	my ($done, $rstatus);
		693
		694	# pass a closure to ->child
		695	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		696	$rstatus = $_[1]; # remember rstatus
		697	$done = 1; # mark $rstatus as valud
		698	});
		699
		700	# wait until the closure has been called
		701	schedule while !$done;
		702
		703	$rstatus
		704	}
		705
		706
605	=head1 BUGS/LIMITATIONS	707	=head1 BUGS/LIMITATIONS
606		708
607	- you must make very sure that no coro is still active on global	709	=over 4
608	destruction. very bad things might happen otherwise (usually segfaults).
609		710
		711	=item fork with pthread backend
		712
		713	When Coro is compiled using the pthread backend (which isn't recommended
		714	but required on many BSDs as their libcs are completely broken), then
		715	coroutines will not survive a fork. There is no known workaround except to
		716	fix your libc and use a saner backend.
		717
		718	=item perl process emulation ("threads")
		719
610	- this module is not thread-safe. You should only ever use this module	720	This module is not perl-pseudo-thread-safe. You should only ever use this
611	from the same thread (this requirement might be loosened in the future	721	module from the same thread (this requirement might be removed in the
612	to allow per-thread schedulers, but Coro::State does not yet allow	722	future to allow per-thread schedulers, but Coro::State does not yet allow
613	this).	723	this). I recommend disabling thread support and using processes, as having
		724	the windows process emulation enabled under unix roughly halves perl
		725	performance, even when not used.
		726
		727	=item coroutine switching not signal safe
		728
		729	You must not switch to another coroutine from within a signal handler
		730	(only relevant with %SIG - most event libraries provide safe signals).
		731
		732	That means you I<MUST NOT> call any function that might "block" the
		733	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		734	anything that calls those. Everything else, including calling C<ready>,
		735	works.
		736
		737	=back
		738
614		739
615	=head1 SEE ALSO	740	=head1 SEE ALSO
616		741
617	Lower level Configuration, Coroutine Environment: L<Coro::State>.	742	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
618		743
619	Debugging: L<Coro::Debug>.	744	Debugging: L<Coro::Debug>.
620		745
621	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	746	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
622		747
623	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	748	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
624		749
625	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	750	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
626		751
627	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	752	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
628		753
629	Embedding: L<Coro::MakeMaker>.	754	XS API: L<Coro::MakeMaker>.
		755
		756	Low level Configuration, Coroutine Environment: L<Coro::State>.
630		757
631	=head1 AUTHOR	758	=head1 AUTHOR
632		759
633	Marc Lehmann <schmorp@schmorp.de>	760	Marc Lehmann <schmorp@schmorp.de>
634	http://home.schmorp.de/	761	http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs. Revision 1.230 by root, Thu Nov 20 07:02:43 2008 UTC

Diff Legend

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs.
Revision 1.230 by root, Thu Nov 20 07:02:43 2008 UTC