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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC vs.
Revision 1.237 by root, Sat Nov 22 16:37:11 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - real threads in perl
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	For a tutorial-style introduction, please read the L<Coro::Intro>
24	to threads but don't run in parallel at the same time even on SMP	32	manpage. This manpage mainly contains reference information.
25	machines. The specific flavor of coroutine used in this module also
26	guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.
30		33
31	(Perl, however, does not natively support real threads but instead does a	34	This module collection manages coroutines, that is, cooperative
32	very slow and memory-intensive emulation of processes using threads. This	35	threads. Coroutines are similar to kernel threads but don't (in general)
33	is a performance win on Windows machines, and a loss everywhere else).	36	run in parallel at the same time even on SMP machines. The specific flavor
		37	of coroutine used in this module also guarantees you that it will not
		38	switch between coroutines unless necessary, at easily-identified points
		39	in your program, so locking and parallel access are rarely an issue,
		40	making coroutine programming much safer and easier than using other thread
		41	models.
34		42
		43	Unlike the so-called "Perl threads" (which are not actually real threads
		44	but only the windows process emulation ported to unix), Coro provides a
		45	full shared address space, which makes communication between coroutines
		46	very easy. And coroutines are fast, too: disabling the Windows process
		47	emulation code in your perl and using Coro can easily result in a two to
		48	four times speed increase for your programs.
		49
		50	Coro achieves that by supporting multiple running interpreters that share
		51	data, which is especially useful to code pseudo-parallel processes and
		52	for event-based programming, such as multiple HTTP-GET requests running
		53	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		54	into an event-based environment.
		55
35	In this module, coroutines are defined as "callchain + lexical variables +	56	In this module, a coroutines is defined as "callchain + lexical variables
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	57	+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own
37	its own set of lexicals and its own set of perls most important global	58	callchain, its own set of lexicals and its own set of perls most important
38	variables.	59	global variables (see L<Coro::State> for more configuration and background
		60	info).
		61
		62	See also the C<SEE ALSO> section at the end of this document - the Coro
		63	module family is quite large.
39		64
40	=cut	65	=cut
41		66
42	package Coro;	67	package Coro;
43		68
44	use strict;	69	use strict qw(vars subs);
45	no warnings "uninitialized";	70	no warnings "uninitialized";
46		71
47	use Coro::State;	72	use Coro::State;
48		73
49	use base qw(Coro::State Exporter);	74	use base qw(Coro::State Exporter);
50		75
51	our $idle; # idle handler	76	our $idle; # idle handler
52	our $main; # main coroutine	77	our $main; # main coroutine
53	our $current; # current coroutine	78	our $current; # current coroutine
54		79
55	our $VERSION = '3.8';	80	our $VERSION = "5.0";
56		81
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	82	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	83	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	84	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	85	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	86	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		87
63	{	88	=head1 GLOBAL VARIABLES
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		89
97	=over 4	90	=over 4
98		91
99	=item $main	92	=item $Coro::main
100		93
101	This coroutine represents the main program.	94	This variable stores the coroutine object that represents the main
		95	program. While you cna C<ready> it and do most other things you can do to
		96	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		97	whether you are running in the main program or not.
102		98
103	=cut	99	=cut
104		100
105	$main = new Coro;	101	# $main is now being initialised by Coro::State
106		102
107	=item $current (or as function: current)	103	=item $Coro::current
108		104
109	The current coroutine (the last coroutine switched to). The initial value	105	The coroutine object representing the current coroutine (the last
		106	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	107	C<$Coro::main> (of course).
111		108
112	This variable is B<strictly> I<read-only>. It is provided for performance	109	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essential you are encouraged to use the	110	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	111	not otherwise modify the variable itself.
115		112
116	=cut	113	=cut
117		114
118	$main->{desc} = "[main::]";
119
120	# maybe some other module used Coro::Specific before...
121	$main->{specific} = $current->{specific}
122	if $current;
123
124	_set_current $main;
125
126	sub current() { $current }	115	sub current() { $current } # [DEPRECATED]
127		116
128	=item $idle	117	=item $Coro::idle
129		118
130	A callback that is called whenever the scheduler finds no ready coroutines	119	This variable is mainly useful to integrate Coro into event loops. It is
131	to run. The default implementation prints "FATAL: deadlock detected" and	120	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
132	exits, because the program has no other way to continue.	121	pretty low-level functionality.
		122
		123	This variable stores a callback that is called whenever the scheduler
		124	finds no ready coroutines to run. The default implementation prints
		125	"FATAL: deadlock detected" and exits, because the program has no other way
		126	to continue.
133		127
134	This hook is overwritten by modules such as C<Coro::Timer> and	128	This hook is overwritten by modules such as C<Coro::Timer> and
135	C<Coro::Event> to wait on an external event that hopefully wake up a	129	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
136	coroutine so the scheduler can run it.	130	coroutine so the scheduler can run it.
137		131
		132	Note that the callback I<must not>, under any circumstances, block
		133	the current coroutine. Normally, this is achieved by having an "idle
		134	coroutine" that calls the event loop and then blocks again, and then
		135	readying that coroutine in the idle handler.
		136
		137	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		138	technique.
		139
138	Please note that if your callback recursively invokes perl (e.g. for event	140	Please note that if your callback recursively invokes perl (e.g. for event
139	handlers), then it must be prepared to be called recursively.	141	handlers), then it must be prepared to be called recursively itself.
140		142
141	=cut	143	=cut
142		144
143	$idle = sub {	145	$idle = sub {
144	require Carp;	146	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	147	Carp::croak ("FATAL: deadlock detected");
146	};	148	};
147		149
148	sub _cancel {
149	my ($self) = @_;
150
151	# free coroutine data and mark as destructed
152	$self->_destroy
153	or return;
154
155	# call all destruction callbacks
156	$_->(@{$self->{status}})
157	for @{(delete $self->{destroy_cb}) \|\| []};
158	}
159
160	sub _do_trace_sub {
161	&{$current->{_trace_sub_cb}}
162	}
163
164	sub _do_trace_line {
165	&{$current->{_trace_line_cb}}
166	}
167
168	# this coroutine is necessary because a coroutine	150	# this coroutine is necessary because a coroutine
169	# cannot destroy itself.	151	# cannot destroy itself.
170	my @destroy;	152	our @destroy;
171	my $manager;	153	our $manager;
172		154
173	$manager = new Coro sub {	155	$manager = new Coro sub {
174	while () {	156	while () {
175	(shift @destroy)->_cancel	157	Coro::_cancel shift @destroy
176	while @destroy;	158	while @destroy;
177		159
178	&schedule;	160	&schedule;
179	}	161	}
180	};	162	};
181	$manager->desc ("[coro manager]");	163	$manager->{desc} = "[coro manager]";
182	$manager->prio (PRIO_MAX);	164	$manager->prio (PRIO_MAX);
183		165
184	# static methods. not really.
185
186	=back	166	=back
187		167
188	=head2 STATIC METHODS	168	=head1 SIMPLE COROUTINE CREATION
189
190	Static methods are actually functions that operate on the current coroutine only.
191		169
192	=over 4	170	=over 4
193		171
194	=item async { ... } [@args...]	172	=item async { ... } [@args...]
195		173
196	Create a new asynchronous coroutine and return it's coroutine object	174	Create a new coroutine and return it's coroutine object (usually
197	(usually unused). When the sub returns the new coroutine is automatically	175	unused). The coroutine will be put into the ready queue, so
		176	it will start running automatically on the next scheduler run.
		177
		178	The first argument is a codeblock/closure that should be executed in the
		179	coroutine. When it returns argument returns the coroutine is automatically
198	terminated.	180	terminated.
		181
		182	The remaining arguments are passed as arguments to the closure.
		183
		184	See the C<Coro::State::new> constructor for info about the coroutine
		185	environment in which coroutines are executed.
199		186
200	Calling C<exit> in a coroutine will do the same as calling exit outside	187	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,	188	the coroutine. Likewise, when the coroutine dies, the program will exit,
202	just as it would in the main program.	189	just as it would in the main program.
203		190
		191	If you do not want that, you can provide a default C<die> handler, or
		192	simply avoid dieing (by use of C<eval>).
		193
204	# create a new coroutine that just prints its arguments	194	Example: Create a new coroutine that just prints its arguments.
		195
205	async {	196	async {
206	print "@_\n";	197	print "@_\n";
207	} 1,2,3,4;	198	} 1,2,3,4;
208		199
209	=cut	200	=cut
215	}	206	}
216		207
217	=item async_pool { ... } [@args...]	208	=item async_pool { ... } [@args...]
218		209
219	Similar to C<async>, but uses a coroutine pool, so you should not call	210	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	211	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 :).	212	coroutine that might have executed other code already (which can be good
		213	or bad :).
222		214
		215	On the plus side, this function is about twice as fast as creating (and
		216	destroying) a completely new coroutine, so if you need a lot of generic
		217	coroutines in quick successsion, use C<async_pool>, not C<async>.
		218
223	Also, the block is executed in an C<eval> context and a warning will be	219	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	220	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>	221	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,	222	will not work in the expected way, unless you call terminate or cancel,
227	which somehow defeats the purpose of pooling.	223	which somehow defeats the purpose of pooling (but is fine in the
		224	exceptional case).
228		225
229	The priority will be reset to C<0> after each job, otherwise the coroutine	226	The priority will be reset to C<0> after each run, tracing will be
230	will be re-used "as-is".	227	disabled, the description will be reset and the default output filehandle
		228	gets restored, so you can change all these. Otherwise the coroutine will
		229	be re-used "as-is": most notably if you change other per-coroutine global
		230	stuff such as C<$/> you I<must needs> revert that change, which is most
		231	simply done by using local as in: C<< local $/ >>.
231		232
232	The pool size is limited to 8 idle coroutines (this can be adjusted by	233	The idle pool size is limited to C<8> idle coroutines (this can be
233	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	234	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
234	required.	235	coros as required.
235		236
236	If you are concerned about pooled coroutines growing a lot because a	237	If you are concerned about pooled coroutines growing a lot because a
237	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	238	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
238	{ terminate }> once per second or so to slowly replenish the pool. In	239	{ terminate }> once per second or so to slowly replenish the pool. In
239	addition to that, when the stacks used by a handler grows larger than 16kb	240	addition to that, when the stacks used by a handler grows larger than 32kb
240	(adjustable with $Coro::POOL_RSS) it will also exit.	241	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
241		242
242	=cut	243	=cut
243		244
244	our $POOL_SIZE = 8;	245	our $POOL_SIZE = 8;
245	our $POOL_RSS = 16 * 1024;	246	our $POOL_RSS = 32 * 1024;
246	our @async_pool;	247	our @async_pool;
247		248
248	sub pool_handler {	249	sub pool_handler {
249	my $cb;
250
251	while () {	250	while () {
252	eval {	251	eval {
253	while () {	252	&{&_pool_handler} while 1;
254	_pool_1 $cb;
255	&$cb;
256	_pool_2 $cb;
257	&schedule;
258	}
259	};	253	};
260		254
261	last if $@ eq "\3terminate\2\n";
262	warn $@ if $@;	255	warn $@ if $@;
263	}	256	}
264	}	257	}
265		258
266	sub async_pool(&@) {	259	=back
267	# this is also inlined into the unlock_scheduler
268	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
269		260
270	$coro->{_invoke} = [@_];	261	=head1 STATIC METHODS
271	$coro->ready;
272		262
273	$coro	263	Static methods are actually functions that implicitly operate on the
274	}	264	current coroutine.
		265
		266	=over 4
275		267
276	=item schedule	268	=item schedule
277		269
278	Calls the scheduler. Please note that the current coroutine will not be put	270	Calls the scheduler. The scheduler will find the next coroutine that is
		271	to be run from the ready queue and switches to it. The next coroutine
		272	to be run is simply the one with the highest priority that is longest
		273	in its ready queue. If there is no coroutine ready, it will clal the
		274	C<$Coro::idle> hook.
		275
		276	Please note that the current coroutine will I<not> be put into the ready
279	into the ready queue, so calling this function usually means you will	277	queue, so calling this function usually means you will never be called
280	never be called again unless something else (e.g. an event handler) calls	278	again unless something else (e.g. an event handler) calls C<< ->ready >>,
281	ready.	279	thus waking you up.
282		280
283	The canonical way to wait on external events is this:	281	This makes C<schedule> I<the> generic method to use to block the current
		282	coroutine and wait for events: first you remember the current coroutine in
		283	a variable, then arrange for some callback of yours to call C<< ->ready
		284	>> on that once some event happens, and last you call C<schedule> to put
		285	yourself to sleep. Note that a lot of things can wake your coroutine up,
		286	so you need to check whether the event indeed happened, e.g. by storing the
		287	status in a variable.
284		288
		289	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		290
		291	=item cede
		292
		293	"Cede" to other coroutines. This function puts the current coroutine into
		294	the ready queue and calls C<schedule>, which has the effect of giving
		295	up the current "timeslice" to other coroutines of the same or higher
		296	priority. Once your coroutine gets its turn again it will automatically be
		297	resumed.
		298
		299	This function is often called C<yield> in other languages.
		300
		301	=item Coro::cede_notself
		302
		303	Works like cede, but is not exported by default and will cede to I<any>
		304	coroutine, regardless of priority. This is useful sometimes to ensure
		305	progress is made.
		306
		307	=item terminate [arg...]
		308
		309	Terminates the current coroutine with the given status values (see L<cancel>).
		310
		311	=item killall
		312
		313	Kills/terminates/cancels all coroutines except the currently running
		314	one. This is useful after a fork, either in the child or the parent, as
		315	usually only one of them should inherit the running coroutines.
		316
		317	Note that while this will try to free some of the main programs resources,
		318	you cannot free all of them, so if a coroutine that is not the main
		319	program calls this function, there will be some one-time resource leak.
		320
		321	=cut
		322
		323	sub killall {
		324	for (Coro::State::list) {
		325	$_->cancel
		326	if $_ != $current && UNIVERSAL::isa $_, "Coro";
285	{	327	}
286	# remember current coroutine	328	}
		329
		330	=back
		331
		332	=head1 COROUTINE OBJECT METHODS
		333
		334	These are the methods you can call on coroutine objects (or to create
		335	them).
		336
		337	=over 4
		338
		339	=item new Coro \&sub [, @args...]
		340
		341	Create a new coroutine and return it. When the sub returns, the coroutine
		342	automatically terminates as if C<terminate> with the returned values were
		343	called. To make the coroutine run you must first put it into the ready
		344	queue by calling the ready method.
		345
		346	See C<async> and C<Coro::State::new> for additional info about the
		347	coroutine environment.
		348
		349	=cut
		350
		351	sub _terminate {
		352	terminate &{+shift};
		353	}
		354
		355	=item $success = $coroutine->ready
		356
		357	Put the given coroutine into the end of its ready queue (there is one
		358	queue for each priority) and return true. If the coroutine is already in
		359	the ready queue, do nothing and return false.
		360
		361	This ensures that the scheduler will resume this coroutine automatically
		362	once all the coroutines of higher priority and all coroutines of the same
		363	priority that were put into the ready queue earlier have been resumed.
		364
		365	=item $is_ready = $coroutine->is_ready
		366
		367	Return whether the coroutine is currently the ready queue or not,
		368
		369	=item $coroutine->cancel (arg...)
		370
		371	Terminates the given coroutine and makes it return the given arguments as
		372	status (default: the empty list). Never returns if the coroutine is the
		373	current coroutine.
		374
		375	=cut
		376
		377	sub cancel {
		378	my $self = shift;
		379
		380	if ($current == $self) {
		381	terminate @_;
		382	} else {
		383	$self->{_status} = [@_];
		384	$self->_cancel;
		385	}
		386	}
		387
		388	=item $coroutine->schedule_to
		389
		390	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		391	of continuing with the next coro from the ready queue, always switch to
		392	the given coroutine object (regardless of priority etc.). The readyness
		393	state of that coroutine isn't changed.
		394
		395	This is an advanced method for special cases - I'd love to hear about any
		396	uses for this one.
		397
		398	=item $coroutine->cede_to
		399
		400	Like C<schedule_to>, but puts the current coroutine into the ready
		401	queue. This has the effect of temporarily switching to the given
		402	coroutine, and continuing some time later.
		403
		404	This is an advanced method for special cases - I'd love to hear about any
		405	uses for this one.
		406
		407	=item $coroutine->throw ([$scalar])
		408
		409	If C<$throw> is specified and defined, it will be thrown as an exception
		410	inside the coroutine at the next convenient point in time. Otherwise
		411	clears the exception object.
		412
		413	Coro will check for the exception each time a schedule-like-function
		414	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		415	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		416	detect this case and return early in case an exception is pending.
		417
		418	The exception object will be thrown "as is" with the specified scalar in
		419	C<$@>, i.e. if it is a string, no line number or newline will be appended
		420	(unlike with C<die>).
		421
		422	This can be used as a softer means than C<cancel> to ask a coroutine to
		423	end itself, although there is no guarantee that the exception will lead to
		424	termination, and if the exception isn't caught it might well end the whole
		425	program.
		426
		427	You might also think of C<throw> as being the moral equivalent of
		428	C<kill>ing a coroutine with a signal (in this case, a scalar).
		429
		430	=item $coroutine->join
		431
		432	Wait until the coroutine terminates and return any values given to the
		433	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		434	from multiple coroutines, and all will be resumed and given the status
		435	return once the C<$coroutine> terminates.
		436
		437	=cut
		438
		439	sub join {
		440	my $self = shift;
		441
		442	unless ($self->{_status}) {
287	my $current = $Coro::current;	443	my $current = $current;
288		444
289	# register a hypothetical event handler	445	push @{$self->{_on_destroy}}, sub {
290	on_event_invoke sub {
291	# wake up sleeping coroutine
292	$current->ready;	446	$current->ready;
293	undef $current;	447	undef $current;
294	};	448	};
295		449
296	# call schedule until event occurred.
297	# in case we are woken up for other reasons
298	# (current still defined), loop.
299	Coro::schedule while $current;
300	}
301
302	=item cede
303
304	"Cede" to other coroutines. This function puts the current coroutine into the
305	ready queue and calls C<schedule>, which has the effect of giving up the
306	current "timeslice" to other coroutines of the same or higher priority.
307
308	Returns true if at least one coroutine switch has happened.
309
310	=item Coro::cede_notself
311
312	Works like cede, but is not exported by default and will cede to any
313	coroutine, regardless of priority, once.
314
315	Returns true if at least one coroutine switch has happened.
316
317	=item terminate [arg...]
318
319	Terminates the current coroutine with the given status values (see L<cancel>).
320
321	=cut
322
323	sub terminate {
324	$current->cancel (@_);
325	}
326
327	=back
328
329	# dynamic methods
330
331	=head2 COROUTINE METHODS
332
333	These are the methods you can call on coroutine objects.
334
335	=over 4
336
337	=item new Coro \&sub [, @args...]
338
339	Create a new coroutine and return it. When the sub returns the coroutine
340	automatically terminates as if C<terminate> with the returned values were
341	called. To make the coroutine run you must first put it into the ready queue
342	by calling the ready method.
343
344	See C<async> for additional discussion.
345
346	=cut
347
348	sub _run_coro {
349	terminate &{+shift};
350	}
351
352	sub new {
353	my $class = shift;
354
355	$class->SUPER::new (\&_run_coro, @_)
356	}
357
358	=item $success = $coroutine->ready
359
360	Put the given coroutine into the ready queue (according to it's priority)
361	and return true. If the coroutine is already in the ready queue, do nothing
362	and return false.
363
364	=item $is_ready = $coroutine->is_ready
365
366	Return wether the coroutine is currently the ready queue or not,
367
368	=item $coroutine->cancel (arg...)
369
370	Terminates the given coroutine and makes it return the given arguments as
371	status (default: the empty list). Never returns if the coroutine is the
372	current coroutine.
373
374	=cut
375
376	sub cancel {
377	my $self = shift;
378	$self->{status} = [@_];
379
380	if ($current == $self) {
381	push @destroy, $self;
382	$manager->ready;
383	&schedule while 1;
384	} else {
385	$self->_cancel;
386	}
387	}
388
389	=item $coroutine->join
390
391	Wait until the coroutine terminates and return any values given to the
392	C<terminate> or C<cancel> functions. C<join> can be called multiple times
393	from multiple coroutine.
394
395	=cut
396
397	sub join {
398	my $self = shift;
399
400	unless ($self->{status}) {
401	my $current = $current;
402
403	push @{$self->{destroy_cb}}, sub {
404	$current->ready;
405	undef $current;
406	};
407
408	&schedule while $current;	450	&schedule while $current;
409	}	451	}
410		452
411	wantarray ? @{$self->{status}} : $self->{status}[0];	453	wantarray ? @{$self->{_status}} : $self->{_status}[0];
412	}	454	}
413		455
414	=item $coroutine->on_destroy (\&cb)	456	=item $coroutine->on_destroy (\&cb)
415		457
416	Registers a callback that is called when this coroutine gets destroyed,	458	Registers a callback that is called when this coroutine gets destroyed,
417	but before it is joined. The callback gets passed the terminate arguments,	459	but before it is joined. The callback gets passed the terminate arguments,
418	if any.	460	if any, and I<must not> die, under any circumstances.
419		461
420	=cut	462	=cut
421		463
422	sub on_destroy {	464	sub on_destroy {
423	my ($self, $cb) = @_;	465	my ($self, $cb) = @_;
424		466
425	push @{ $self->{destroy_cb} }, $cb;	467	push @{ $self->{_on_destroy} }, $cb;
426	}	468	}
427		469
428	=item $oldprio = $coroutine->prio ($newprio)	470	=item $oldprio = $coroutine->prio ($newprio)
429		471
430	Sets (or gets, if the argument is missing) the priority of the	472	Sets (or gets, if the argument is missing) the priority of the
…		…
453	higher values mean lower priority, just as in unix).	495	higher values mean lower priority, just as in unix).
454		496
455	=item $olddesc = $coroutine->desc ($newdesc)	497	=item $olddesc = $coroutine->desc ($newdesc)
456		498
457	Sets (or gets in case the argument is missing) the description for this	499	Sets (or gets in case the argument is missing) the description for this
458	coroutine. This is just a free-form string you can associate with a coroutine.	500	coroutine. This is just a free-form string you can associate with a
		501	coroutine.
		502
		503	This method simply sets the C<< $coroutine->{desc} >> member to the given
		504	string. You can modify this member directly if you wish.
459		505
460	=cut	506	=cut
461		507
462	sub desc {	508	sub desc {
463	my $old = $_[0]{desc};	509	my $old = $_[0]{desc};
464	$_[0]{desc} = $_[1] if @_ > 1;	510	$_[0]{desc} = $_[1] if @_ > 1;
465	$old;	511	$old;
466	}	512	}
467		513
		514	sub transfer {
		515	require Carp;
		516	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		517	}
		518
468	=back	519	=back
469		520
470	=head2 GLOBAL FUNCTIONS	521	=head1 GLOBAL FUNCTIONS
471		522
472	=over 4	523	=over 4
473		524
474	=item Coro::nready	525	=item Coro::nready
475		526
476	Returns the number of coroutines that are currently in the ready state,	527	Returns the number of coroutines that are currently in the ready state,
477	i.e. that can be switched to. The value C<0> means that the only runnable	528	i.e. that can be switched to by calling C<schedule> directory or
		529	indirectly. The value C<0> means that the only runnable coroutine is the
478	coroutine is the currently running one, so C<cede> would have no effect,	530	currently running one, so C<cede> would have no effect, and C<schedule>
479	and C<schedule> would cause a deadlock unless there is an idle handler	531	would cause a deadlock unless there is an idle handler that wakes up some
480	that wakes up some coroutines.	532	coroutines.
481		533
482	=item my $guard = Coro::guard { ... }	534	=item my $guard = Coro::guard { ... }
483		535
484	This creates and returns a guard object. Nothing happens until the object	536	This creates and returns a guard object. Nothing happens until the object
485	gets destroyed, in which case the codeblock given as argument will be	537	gets destroyed, in which case the codeblock given as argument will be
…		…
514		566
515		567
516	=item unblock_sub { ... }	568	=item unblock_sub { ... }
517		569
518	This utility function takes a BLOCK or code reference and "unblocks" it,	570	This utility function takes a BLOCK or code reference and "unblocks" it,
519	returning the new coderef. This means that the new coderef will return	571	returning a new coderef. Unblocking means that calling the new coderef
520	immediately without blocking, returning nothing, while the original code	572	will return immediately without blocking, returning nothing, while the
521	ref will be called (with parameters) from within its own coroutine.	573	original code ref will be called (with parameters) from within another
		574	coroutine.
522		575
523	The reason this function exists is that many event libraries (such as the	576	The reason this function exists is that many event libraries (such as the
524	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	577	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
525	of thread-safety). This means you must not block within event callbacks,	578	of thread-safety). This means you must not block within event callbacks,
526	otherwise you might suffer from crashes or worse.	579	otherwise you might suffer from crashes or worse. The only event library
		580	currently known that is safe to use without C<unblock_sub> is L<EV>.
527		581
528	This function allows your callbacks to block by executing them in another	582	This function allows your callbacks to block by executing them in another
529	coroutine where it is safe to block. One example where blocking is handy	583	coroutine where it is safe to block. One example where blocking is handy
530	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	584	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
531	disk.	585	disk, for example.
532		586
533	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	587	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
534	creating event callbacks that want to block.	588	creating event callbacks that want to block.
		589
		590	If your handler does not plan to block (e.g. simply sends a message to
		591	another coroutine, or puts some other coroutine into the ready queue),
		592	there is no reason to use C<unblock_sub>.
		593
		594	Note that you also need to use C<unblock_sub> for any other callbacks that
		595	are indirectly executed by any C-based event loop. For example, when you
		596	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		597	provides callbacks that are the result of some event callback, then you
		598	must not block either, or use C<unblock_sub>.
535		599
536	=cut	600	=cut
537		601
538	our @unblock_queue;	602	our @unblock_queue;
539		603
…		…
542	# return immediately and can be reused) and because we cannot cede	606	# return immediately and can be reused) and because we cannot cede
543	# inside an event callback.	607	# inside an event callback.
544	our $unblock_scheduler = new Coro sub {	608	our $unblock_scheduler = new Coro sub {
545	while () {	609	while () {
546	while (my $cb = pop @unblock_queue) {	610	while (my $cb = pop @unblock_queue) {
547	# this is an inlined copy of async_pool	611	&async_pool (@$cb);
548	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
549		612
550	$coro->{_invoke} = $cb;
551	$coro->ready;
552	cede; # for short-lived callbacks, this reduces pressure on the coro pool	613	# for short-lived callbacks, this reduces pressure on the coro pool
		614	# as the chance is very high that the async_poll coro will be back
		615	# in the idle state when cede returns
		616	cede;
553	}	617	}
554	schedule; # sleep well	618	schedule; # sleep well
555	}	619	}
556	};	620	};
557	$unblock_scheduler->desc ("[unblock_sub scheduler]");	621	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
558		622
559	sub unblock_sub(&) {	623	sub unblock_sub(&) {
560	my $cb = shift;	624	my $cb = shift;
561		625
562	sub {	626	sub {
563	unshift @unblock_queue, [$cb, @_];	627	unshift @unblock_queue, [$cb, @_];
564	$unblock_scheduler->ready;	628	$unblock_scheduler->ready;
565	}	629	}
566	}	630	}
567		631
		632	=item $cb = Coro::rouse_cb
		633
		634	Create and return a "rouse callback". That's a code reference that, when
		635	called, will save its arguments and notify the owner coroutine of the
		636	callback.
		637
		638	See the next function.
		639
		640	=item @args = Coro::rouse_wait [$cb]
		641
		642	Wait for the specified rouse callback (or the last one tht was created in
		643	this coroutine).
		644
		645	As soon as the callback is invoked (or when the calback was invoked before
		646	C<rouse_wait>), it will return a copy of the arguments originally passed
		647	to the rouse callback.
		648
		649	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		650
568	=back	651	=back
569		652
570	=cut	653	=cut
571		654
572	1;	655	1;
573		656
		657	=head1 HOW TO WAIT FOR A CALLBACK
		658
		659	It is very common for a coroutine to wait for some callback to be
		660	called. This occurs naturally when you use coroutines in an otherwise
		661	event-based program, or when you use event-based libraries.
		662
		663	These typically register a callback for some event, and call that callback
		664	when the event occured. In a coroutine, however, you typically want to
		665	just wait for the event, simplyifying things.
		666
		667	For example C<< AnyEvent->child >> registers a callback to be called when
		668	a specific child has exited:
		669
		670	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		671
		672	But from withina coroutine, you often just want to write this:
		673
		674	my $status = wait_for_child $pid;
		675
		676	Coro offers two functions specifically designed to make this easy,
		677	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		678
		679	The first function, C<rouse_cb>, generates and returns a callback that,
		680	when invoked, will save it's arguments and notify the coroutine that
		681	created the callback.
		682
		683	The second function, C<rouse_wait>, waits for the callback to be called
		684	(by calling C<schedule> to go to sleep) and returns the arguments
		685	originally passed to the callback.
		686
		687	Using these functions, it becomes easy to write the C<wait_for_child>
		688	function mentioned above:
		689
		690	sub wait_for_child($) {
		691	my ($pid) = @_;
		692
		693	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		694
		695	my ($rpid, $rstatus) = Coro::rouse_wait;
		696	$rstatus
		697	}
		698
		699	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		700	you can roll your own, using C<schedule>:
		701
		702	sub wait_for_child($) {
		703	my ($pid) = @_;
		704
		705	# store the current coroutine in $current,
		706	# and provide result variables for the closure passed to ->child
		707	my $current = $Coro::current;
		708	my ($done, $rstatus);
		709
		710	# pass a closure to ->child
		711	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		712	$rstatus = $_[1]; # remember rstatus
		713	$done = 1; # mark $rstatus as valud
		714	});
		715
		716	# wait until the closure has been called
		717	schedule while !$done;
		718
		719	$rstatus
		720	}
		721
		722
574	=head1 BUGS/LIMITATIONS	723	=head1 BUGS/LIMITATIONS
575		724
576	- you must make very sure that no coro is still active on global	725	=over 4
577	destruction. very bad things might happen otherwise (usually segfaults).
578		726
		727	=item fork with pthread backend
		728
		729	When Coro is compiled using the pthread backend (which isn't recommended
		730	but required on many BSDs as their libcs are completely broken), then
		731	coroutines will not survive a fork. There is no known workaround except to
		732	fix your libc and use a saner backend.
		733
		734	=item perl process emulation ("threads")
		735
579	- this module is not thread-safe. You should only ever use this module	736	This module is not perl-pseudo-thread-safe. You should only ever use this
580	from the same thread (this requirement might be loosened in the future	737	module from the same thread (this requirement might be removed in the
581	to allow per-thread schedulers, but Coro::State does not yet allow	738	future to allow per-thread schedulers, but Coro::State does not yet allow
582	this).	739	this). I recommend disabling thread support and using processes, as having
		740	the windows process emulation enabled under unix roughly halves perl
		741	performance, even when not used.
		742
		743	=item coroutine switching not signal safe
		744
		745	You must not switch to another coroutine from within a signal handler
		746	(only relevant with %SIG - most event libraries provide safe signals).
		747
		748	That means you I<MUST NOT> call any function that might "block" the
		749	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		750	anything that calls those. Everything else, including calling C<ready>,
		751	works.
		752
		753	=back
		754
583		755
584	=head1 SEE ALSO	756	=head1 SEE ALSO
585		757
		758	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		759
		760	Debugging: L<Coro::Debug>.
		761
586	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	762	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
587		763
588	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	764	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		765	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
589		766
590	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	767	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
591		768
592	Embedding: L<Coro:MakeMaker>	769	Compatibility: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		770	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		771	L<Coro::Select>.
		772
		773	XS API: L<Coro::MakeMaker>.
		774
		775	Low level Configuration, Coroutine Environment: L<Coro::State>.
593		776
594	=head1 AUTHOR	777	=head1 AUTHOR
595		778
596	Marc Lehmann <schmorp@schmorp.de>	779	Marc Lehmann <schmorp@schmorp.de>
597	http://home.schmorp.de/	780	http://home.schmorp.de/

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Revision 1.237 by root, Sat Nov 22 16:37:11 2008 UTC