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

Comparing Coro/Coro.pm (file contents):
Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC vs.
Revision 1.234 by root, Fri Nov 21 06:52:10 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the real perl threads
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coroutine
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	This module collection manages coroutines, that is, cooperative
24	to threads but don't run in parallel at the same time even on SMP	32	threads. Coroutines are similar to kernel threads but don't (in general)
25	machines. The specific flavor of coroutine use din this module also	33	run in parallel at the same time even on SMP machines. The specific flavor
26	guarentees you that it will not switch between coroutines unless	34	of coroutine used in this module also guarantees you that it will not
27	necessary, at easily-identified points in your program, so locking and	35	switch between coroutines unless necessary, at easily-identified points
28	parallel access are rarely an issue, making coroutine programming much	36	in your program, so locking and parallel access are rarely an issue,
29	safer than threads programming.	37	making coroutine programming much safer and easier than using other thread
		38	models.
30		39
31	(Perl, however, does not natively support real threads but instead does a	40	Unlike the so-called "Perl threads" (which are not actually real threads
32	very slow and memory-intensive emulation of processes using threads. This	41	but only the windows process emulation ported to unix), Coro provides a
33	is a performance win on Windows machines, and a loss everywhere else).	42	full shared address space, which makes communication between coroutines
		43	very easy. And coroutines are fast, too: disabling the Windows process
		44	emulation code in your perl and using Coro can easily result in a two to
		45	four times speed increase for your programs.
34		46
		47	Coro achieves that by supporting multiple running interpreters that share
		48	data, which is especially useful to code pseudo-parallel processes and
		49	for event-based programming, such as multiple HTTP-GET requests running
		50	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		51	into an event-based environment.
		52
35	In this module, coroutines are defined as "callchain + lexical variables +	53	In this module, a coroutines is defined as "callchain + lexical variables
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	54	+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own
37	its own set of lexicals and its own set of perls most important global	55	callchain, its own set of lexicals and its own set of perls most important
38	variables.	56	global variables (see L<Coro::State> for more configuration and background
		57	info).
		58
		59	See also the C<SEE ALSO> section at the end of this document - the Coro
		60	module family is quite large.
39		61
40	=cut	62	=cut
41		63
42	package Coro;	64	package Coro;
43		65
44	use strict;	66	use strict qw(vars subs);
45	no warnings "uninitialized";	67	no warnings "uninitialized";
46		68
47	use Coro::State;	69	use Coro::State;
48		70
49	use base qw(Coro::State Exporter);	71	use base qw(Coro::State Exporter);
50		72
51	our $idle; # idle handler	73	our $idle; # idle handler
52	our $main; # main coroutine	74	our $main; # main coroutine
53	our $current; # current coroutine	75	our $current; # current coroutine
54		76
55	our $VERSION = '3.3';	77	our $VERSION = "5.0";
56		78
57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	79	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	80	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	81	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	82	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	83	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		84
63	{	85	=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		86
97	=over 4	87	=over 4
98		88
99	=item $main	89	=item $Coro::main
100		90
101	This coroutine represents the main program.	91	This variable stores the coroutine object that represents the main
		92	program. While you cna C<ready> it and do most other things you can do to
		93	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		94	whether you are running in the main program or not.
102		95
103	=cut	96	=cut
104		97
105	$main = new Coro;	98	# $main is now being initialised by Coro::State
106		99
107	=item $current (or as function: current)	100	=item $Coro::current
108		101
109	The current coroutine (the last coroutine switched to). The initial value	102	The coroutine object representing the current coroutine (the last
		103	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	104	C<$Coro::main> (of course).
111		105
112	This variable is B<strictly> I<read-only>. It is provided for performance	106	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essentiel you are encouraged to use the	107	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	108	not otherwise modify the variable itself.
115		109
116	=cut	110	=cut
117		111
118	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}
120	if $current;
121
122	_set_current $main;
123
124	sub current() { $current }	112	sub current() { $current } # [DEPRECATED]
125		113
126	=item $idle	114	=item $Coro::idle
127		115
128	A callback that is called whenever the scheduler finds no ready coroutines	116	This variable is mainly useful to integrate Coro into event loops. It is
129	to run. The default implementation prints "FATAL: deadlock detected" and	117	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
130	exits, because the program has no other way to continue.	118	pretty low-level functionality.
		119
		120	This variable stores a callback that is called whenever the scheduler
		121	finds no ready coroutines to run. The default implementation prints
		122	"FATAL: deadlock detected" and exits, because the program has no other way
		123	to continue.
131		124
132	This hook is overwritten by modules such as C<Coro::Timer> and	125	This hook is overwritten by modules such as C<Coro::Timer> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a	126	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.	127	coroutine so the scheduler can run it.
135		128
		129	Note that the callback I<must not>, under any circumstances, block
		130	the current coroutine. Normally, this is achieved by having an "idle
		131	coroutine" that calls the event loop and then blocks again, and then
		132	readying that coroutine in the idle handler.
		133
		134	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		135	technique.
		136
136	Please note that if your callback recursively invokes perl (e.g. for event	137	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.	138	handlers), then it must be prepared to be called recursively itself.
138		139
139	=cut	140	=cut
140		141
141	$idle = sub {	142	$idle = sub {
142	require Carp;	143	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	144	Carp::croak ("FATAL: deadlock detected");
144	};	145	};
145		146
146	sub _cancel {
147	my ($self) = @_;
148
149	# free coroutine data and mark as destructed
150	$self->_destroy
151	or return;
152
153	# call all destruction callbacks
154	$_->(@{$self->{status}})
155	for @{(delete $self->{destroy_cb}) \|\| []};
156	}
157
158	# this coroutine is necessary because a coroutine	147	# this coroutine is necessary because a coroutine
159	# cannot destroy itself.	148	# cannot destroy itself.
160	my @destroy;	149	our @destroy;
161	my $manager;	150	our $manager;
162		151
163	$manager = new Coro sub {	152	$manager = new Coro sub {
164	while () {	153	while () {
165	(shift @destroy)->_cancel	154	Coro::_cancel shift @destroy
166	while @destroy;	155	while @destroy;
167		156
168	&schedule;	157	&schedule;
169	}	158	}
170	};	159	};
171		160	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	161	$manager->prio (PRIO_MAX);
173		162
174	# static methods. not really.
175
176	=back	163	=back
177		164
178	=head2 STATIC METHODS	165	=head1 SIMPLE COROUTINE CREATION
179
180	Static methods are actually functions that operate on the current coroutine only.
181		166
182	=over 4	167	=over 4
183		168
184	=item async { ... } [@args...]	169	=item async { ... } [@args...]
185		170
186	Create a new asynchronous coroutine and return it's coroutine object	171	Create a new coroutine and return it's coroutine object (usually
187	(usually unused). When the sub returns the new coroutine is automatically	172	unused). The coroutine will be put into the ready queue, so
		173	it will start running automatically on the next scheduler run.
		174
		175	The first argument is a codeblock/closure that should be executed in the
		176	coroutine. When it returns argument returns the coroutine is automatically
188	terminated.	177	terminated.
189		178
190	Calling C<exit> in a coroutine will not work correctly, so do not do that.	179	The remaining arguments are passed as arguments to the closure.
191		180
192	When the coroutine dies, the program will exit, just as in the main	181	See the C<Coro::State::new> constructor for info about the coroutine
193	program.	182	environment in which coroutines are executed.
194		183
		184	Calling C<exit> in a coroutine will do the same as calling exit outside
		185	the coroutine. Likewise, when the coroutine dies, the program will exit,
		186	just as it would in the main program.
		187
		188	If you do not want that, you can provide a default C<die> handler, or
		189	simply avoid dieing (by use of C<eval>).
		190
195	# create a new coroutine that just prints its arguments	191	Example: Create a new coroutine that just prints its arguments.
		192
196	async {	193	async {
197	print "@_\n";	194	print "@_\n";
198	} 1,2,3,4;	195	} 1,2,3,4;
199		196
200	=cut	197	=cut
203	my $coro = new Coro @_;	200	my $coro = new Coro @_;
204	$coro->ready;	201	$coro->ready;
205	$coro	202	$coro
206	}	203	}
207		204
		205	=item async_pool { ... } [@args...]
		206
		207	Similar to C<async>, but uses a coroutine pool, so you should not call
		208	terminate or join on it (although you are allowed to), and you get a
		209	coroutine that might have executed other code already (which can be good
		210	or bad :).
		211
		212	On the plus side, this function is about twice as fast as creating (and
		213	destroying) a completely new coroutine, so if you need a lot of generic
		214	coroutines in quick successsion, use C<async_pool>, not C<async>.
		215
		216	The code block is executed in an C<eval> context and a warning will be
		217	issued in case of an exception instead of terminating the program, as
		218	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		219	will not work in the expected way, unless you call terminate or cancel,
		220	which somehow defeats the purpose of pooling (but is fine in the
		221	exceptional case).
		222
		223	The priority will be reset to C<0> after each run, tracing will be
		224	disabled, the description will be reset and the default output filehandle
		225	gets restored, so you can change all these. Otherwise the coroutine will
		226	be re-used "as-is": most notably if you change other per-coroutine global
		227	stuff such as C<$/> you I<must needs> revert that change, which is most
		228	simply done by using local as in: C<< local $/ >>.
		229
		230	The idle pool size is limited to C<8> idle coroutines (this can be
		231	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
		232	coros as required.
		233
		234	If you are concerned about pooled coroutines growing a lot because a
		235	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		236	{ terminate }> once per second or so to slowly replenish the pool. In
		237	addition to that, when the stacks used by a handler grows larger than 32kb
		238	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		239
		240	=cut
		241
		242	our $POOL_SIZE = 8;
		243	our $POOL_RSS = 32 * 1024;
		244	our @async_pool;
		245
		246	sub pool_handler {
		247	while () {
		248	eval {
		249	&{&_pool_handler} while 1;
		250	};
		251
		252	warn $@ if $@;
		253	}
		254	}
		255
		256	=back
		257
		258	=head1 STATIC METHODS
		259
		260	Static methods are actually functions that implicitly operate on the
		261	current coroutine.
		262
		263	=over 4
		264
208	=item schedule	265	=item schedule
209		266
210	Calls the scheduler. Please note that the current coroutine will not be put	267	Calls the scheduler. The scheduler will find the next coroutine that is
		268	to be run from the ready queue and switches to it. The next coroutine
		269	to be run is simply the one with the highest priority that is longest
		270	in its ready queue. If there is no coroutine ready, it will clal the
		271	C<$Coro::idle> hook.
		272
		273	Please note that the current coroutine will I<not> be put into the ready
211	into the ready queue, so calling this function usually means you will	274	queue, so calling this function usually means you will never be called
212	never be called again unless something else (e.g. an event handler) calls	275	again unless something else (e.g. an event handler) calls C<< ->ready >>,
213	ready.	276	thus waking you up.
214		277
215	The canonical way to wait on external events is this:	278	This makes C<schedule> I<the> generic method to use to block the current
		279	coroutine and wait for events: first you remember the current coroutine in
		280	a variable, then arrange for some callback of yours to call C<< ->ready
		281	>> on that once some event happens, and last you call C<schedule> to put
		282	yourself to sleep. Note that a lot of things can wake your coroutine up,
		283	so you need to check whether the event indeed happened, e.g. by storing the
		284	status in a variable.
216		285
		286	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		287
		288	=item cede
		289
		290	"Cede" to other coroutines. This function puts the current coroutine into
		291	the ready queue and calls C<schedule>, which has the effect of giving
		292	up the current "timeslice" to other coroutines of the same or higher
		293	priority. Once your coroutine gets its turn again it will automatically be
		294	resumed.
		295
		296	This function is often called C<yield> in other languages.
		297
		298	=item Coro::cede_notself
		299
		300	Works like cede, but is not exported by default and will cede to I<any>
		301	coroutine, regardless of priority. This is useful sometimes to ensure
		302	progress is made.
		303
		304	=item terminate [arg...]
		305
		306	Terminates the current coroutine with the given status values (see L<cancel>).
		307
		308	=item killall
		309
		310	Kills/terminates/cancels all coroutines except the currently running
		311	one. This is useful after a fork, either in the child or the parent, as
		312	usually only one of them should inherit the running coroutines.
		313
		314	Note that while this will try to free some of the main programs resources,
		315	you cannot free all of them, so if a coroutine that is not the main
		316	program calls this function, there will be some one-time resource leak.
		317
		318	=cut
		319
		320	sub killall {
		321	for (Coro::State::list) {
		322	$_->cancel
		323	if $_ != $current && UNIVERSAL::isa $_, "Coro";
217	{	324	}
218	# remember current coroutine	325	}
		326
		327	=back
		328
		329	=head1 COROUTINE OBJECT METHODS
		330
		331	These are the methods you can call on coroutine objects (or to create
		332	them).
		333
		334	=over 4
		335
		336	=item new Coro \&sub [, @args...]
		337
		338	Create a new coroutine and return it. When the sub returns, the coroutine
		339	automatically terminates as if C<terminate> with the returned values were
		340	called. To make the coroutine run you must first put it into the ready
		341	queue by calling the ready method.
		342
		343	See C<async> and C<Coro::State::new> for additional info about the
		344	coroutine environment.
		345
		346	=cut
		347
		348	sub _terminate {
		349	terminate &{+shift};
		350	}
		351
		352	=item $success = $coroutine->ready
		353
		354	Put the given coroutine into the end of its ready queue (there is one
		355	queue for each priority) and return true. If the coroutine is already in
		356	the ready queue, do nothing and return false.
		357
		358	This ensures that the scheduler will resume this coroutine automatically
		359	once all the coroutines of higher priority and all coroutines of the same
		360	priority that were put into the ready queue earlier have been resumed.
		361
		362	=item $is_ready = $coroutine->is_ready
		363
		364	Return whether the coroutine is currently the ready queue or not,
		365
		366	=item $coroutine->cancel (arg...)
		367
		368	Terminates the given coroutine and makes it return the given arguments as
		369	status (default: the empty list). Never returns if the coroutine is the
		370	current coroutine.
		371
		372	=cut
		373
		374	sub cancel {
		375	my $self = shift;
		376
		377	if ($current == $self) {
		378	terminate @_;
		379	} else {
		380	$self->{_status} = [@_];
		381	$self->_cancel;
		382	}
		383	}
		384
		385	=item $coroutine->schedule_to
		386
		387	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		388	of continuing with the next coro from the ready queue, always switch to
		389	the given coroutine object (regardless of priority etc.). The readyness
		390	state of that coroutine isn't changed.
		391
		392	This is an advanced method for special cases - I'd love to hear about any
		393	uses for this one.
		394
		395	=item $coroutine->cede_to
		396
		397	Like C<schedule_to>, but puts the current coroutine into the ready
		398	queue. This has the effect of temporarily switching to the given
		399	coroutine, and continuing some time later.
		400
		401	This is an advanced method for special cases - I'd love to hear about any
		402	uses for this one.
		403
		404	=item $coroutine->throw ([$scalar])
		405
		406	If C<$throw> is specified and defined, it will be thrown as an exception
		407	inside the coroutine at the next convenient point in time. Otherwise
		408	clears the exception object.
		409
		410	Coro will check for the exception each time a schedule-like-function
		411	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		412	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		413	detect this case and return early in case an exception is pending.
		414
		415	The exception object will be thrown "as is" with the specified scalar in
		416	C<$@>, i.e. if it is a string, no line number or newline will be appended
		417	(unlike with C<die>).
		418
		419	This can be used as a softer means than C<cancel> to ask a coroutine to
		420	end itself, although there is no guarantee that the exception will lead to
		421	termination, and if the exception isn't caught it might well end the whole
		422	program.
		423
		424	You might also think of C<throw> as being the moral equivalent of
		425	C<kill>ing a coroutine with a signal (in this case, a scalar).
		426
		427	=item $coroutine->join
		428
		429	Wait until the coroutine terminates and return any values given to the
		430	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		431	from multiple coroutines, and all will be resumed and given the status
		432	return once the C<$coroutine> terminates.
		433
		434	=cut
		435
		436	sub join {
		437	my $self = shift;
		438
		439	unless ($self->{_status}) {
219	my $current = $Coro::current;	440	my $current = $current;
220		441
221	# register a hypothetical event handler	442	push @{$self->{_on_destroy}}, sub {
222	on_event_invoke sub {
223	# wake up sleeping coroutine
224	$current->ready;	443	$current->ready;
225	undef $current;	444	undef $current;
226	};	445	};
227		446
228	# call schedule until event occured.
229	# in case we are woken up for other reasons
230	# (current still defined), loop.
231	Coro::schedule while $current;
232	}
233
234	=item cede
235
236	"Cede" to other coroutines. This function puts the current coroutine into the
237	ready queue and calls C<schedule>, which has the effect of giving up the
238	current "timeslice" to other coroutines of the same or higher priority.
239
240	=item Coro::cede_notself
241
242	Works like cede, but is not exported by default and will cede to any
243	coroutine, regardless of priority, once.
244
245	=item terminate [arg...]
246
247	Terminates the current coroutine with the given status values (see L<cancel>).
248
249	=cut
250
251	sub terminate {
252	$current->cancel (@_);
253	}
254
255	=back
256
257	# dynamic methods
258
259	=head2 COROUTINE METHODS
260
261	These are the methods you can call on coroutine objects.
262
263	=over 4
264
265	=item new Coro \&sub [, @args...]
266
267	Create a new coroutine and return it. When the sub returns the coroutine
268	automatically terminates as if C<terminate> with the returned values were
269	called. To make the coroutine run you must first put it into the ready queue
270	by calling the ready method.
271
272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
273
274	=cut
275
276	sub _run_coro {
277	terminate &{+shift};
278	}
279
280	sub new {
281	my $class = shift;
282
283	$class->SUPER::new (\&_run_coro, @_)
284	}
285
286	=item $success = $coroutine->ready
287
288	Put the given coroutine into the ready queue (according to it's priority)
289	and return true. If the coroutine is already in the ready queue, do nothing
290	and return false.
291
292	=item $is_ready = $coroutine->is_ready
293
294	Return wether the coroutine is currently the ready queue or not,
295
296	=item $coroutine->cancel (arg...)
297
298	Terminates the given coroutine and makes it return the given arguments as
299	status (default: the empty list). Never returns if the coroutine is the
300	current coroutine.
301
302	=cut
303
304	sub cancel {
305	my $self = shift;
306	$self->{status} = [@_];
307
308	if ($current == $self) {
309	push @destroy, $self;
310	$manager->ready;
311	&schedule while 1;
312	} else {
313	$self->_cancel;
314	}
315	}
316
317	=item $coroutine->join
318
319	Wait until the coroutine terminates and return any values given to the
320	C<terminate> or C<cancel> functions. C<join> can be called multiple times
321	from multiple coroutine.
322
323	=cut
324
325	sub join {
326	my $self = shift;
327
328	unless ($self->{status}) {
329	my $current = $current;
330
331	push @{$self->{destroy_cb}}, sub {
332	$current->ready;
333	undef $current;
334	};
335
336	&schedule while $current;	447	&schedule while $current;
337	}	448	}
338		449
339	wantarray ? @{$self->{status}} : $self->{status}[0];	450	wantarray ? @{$self->{_status}} : $self->{_status}[0];
340	}	451	}
341		452
342	=item $coroutine->on_destroy (\&cb)	453	=item $coroutine->on_destroy (\&cb)
343		454
344	Registers a callback that is called when this coroutine gets destroyed,	455	Registers a callback that is called when this coroutine gets destroyed,
345	but before it is joined. The callback gets passed the terminate arguments,	456	but before it is joined. The callback gets passed the terminate arguments,
346	if any.	457	if any, and I<must not> die, under any circumstances.
347		458
348	=cut	459	=cut
349		460
350	sub on_destroy {	461	sub on_destroy {
351	my ($self, $cb) = @_;	462	my ($self, $cb) = @_;
352		463
353	push @{ $self->{destroy_cb} }, $cb;	464	push @{ $self->{_on_destroy} }, $cb;
354	}	465	}
355		466
356	=item $oldprio = $coroutine->prio ($newprio)	467	=item $oldprio = $coroutine->prio ($newprio)
357		468
358	Sets (or gets, if the argument is missing) the priority of the	469	Sets (or gets, if the argument is missing) the priority of the
…		…
381	higher values mean lower priority, just as in unix).	492	higher values mean lower priority, just as in unix).
382		493
383	=item $olddesc = $coroutine->desc ($newdesc)	494	=item $olddesc = $coroutine->desc ($newdesc)
384		495
385	Sets (or gets in case the argument is missing) the description for this	496	Sets (or gets in case the argument is missing) the description for this
386	coroutine. This is just a free-form string you can associate with a coroutine.	497	coroutine. This is just a free-form string you can associate with a
		498	coroutine.
		499
		500	This method simply sets the C<< $coroutine->{desc} >> member to the given
		501	string. You can modify this member directly if you wish.
387		502
388	=cut	503	=cut
389		504
390	sub desc {	505	sub desc {
391	my $old = $_[0]{desc};	506	my $old = $_[0]{desc};
392	$_[0]{desc} = $_[1] if @_ > 1;	507	$_[0]{desc} = $_[1] if @_ > 1;
393	$old;	508	$old;
394	}	509	}
395		510
		511	sub transfer {
		512	require Carp;
		513	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		514	}
		515
396	=back	516	=back
397		517
398	=head2 GLOBAL FUNCTIONS	518	=head1 GLOBAL FUNCTIONS
399		519
400	=over 4	520	=over 4
401		521
402	=item Coro::nready	522	=item Coro::nready
403		523
404	Returns the number of coroutines that are currently in the ready state,	524	Returns the number of coroutines that are currently in the ready state,
405	i.e. that can be swicthed to. The value C<0> means that the only runnable	525	i.e. that can be switched to by calling C<schedule> directory or
		526	indirectly. The value C<0> means that the only runnable coroutine is the
406	coroutine is the currently running one, so C<cede> would have no effect,	527	currently running one, so C<cede> would have no effect, and C<schedule>
407	and C<schedule> would cause a deadlock unless there is an idle handler	528	would cause a deadlock unless there is an idle handler that wakes up some
408	that wakes up some coroutines.	529	coroutines.
409		530
410	=item my $guard = Coro::guard { ... }	531	=item my $guard = Coro::guard { ... }
411		532
412	This creates and returns a guard object. Nothing happens until the objetc	533	This creates and returns a guard object. Nothing happens until the object
413	gets destroyed, in which case the codeblock given as argument will be	534	gets destroyed, in which case the codeblock given as argument will be
414	executed. This is useful to free locks or other resources in case of a	535	executed. This is useful to free locks or other resources in case of a
415	runtime error or when the coroutine gets canceled, as in both cases the	536	runtime error or when the coroutine gets canceled, as in both cases the
416	guard block will be executed. The guard object supports only one method,	537	guard block will be executed. The guard object supports only one method,
417	C<< ->cancel >>, which will keep the codeblock from being executed.	538	C<< ->cancel >>, which will keep the codeblock from being executed.
…		…
442		563
443		564
444	=item unblock_sub { ... }	565	=item unblock_sub { ... }
445		566
446	This utility function takes a BLOCK or code reference and "unblocks" it,	567	This utility function takes a BLOCK or code reference and "unblocks" it,
447	returning the new coderef. This means that the new coderef will return	568	returning a new coderef. Unblocking means that calling the new coderef
448	immediately without blocking, returning nothing, while the original code	569	will return immediately without blocking, returning nothing, while the
449	ref will be called (with parameters) from within its own coroutine.	570	original code ref will be called (with parameters) from within another
		571	coroutine.
450		572
451	The reason this fucntion exists is that many event libraries (such as the	573	The reason this function exists is that many event libraries (such as the
452	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	574	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
453	of thread-safety). This means you must not block within event callbacks,	575	of thread-safety). This means you must not block within event callbacks,
454	otherwise you might suffer from crashes or worse.	576	otherwise you might suffer from crashes or worse. The only event library
		577	currently known that is safe to use without C<unblock_sub> is L<EV>.
455		578
456	This function allows your callbacks to block by executing them in another	579	This function allows your callbacks to block by executing them in another
457	coroutine where it is safe to block. One example where blocking is handy	580	coroutine where it is safe to block. One example where blocking is handy
458	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	581	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
459	disk.	582	disk, for example.
460		583
461	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	584	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
462	creating event callbacks that want to block.	585	creating event callbacks that want to block.
463		586
464	=cut	587	If your handler does not plan to block (e.g. simply sends a message to
		588	another coroutine, or puts some other coroutine into the ready queue),
		589	there is no reason to use C<unblock_sub>.
465		590
466	our @unblock_pool;	591	Note that you also need to use C<unblock_sub> for any other callbacks that
		592	are indirectly executed by any C-based event loop. For example, when you
		593	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		594	provides callbacks that are the result of some event callback, then you
		595	must not block either, or use C<unblock_sub>.
		596
		597	=cut
		598
467	our @unblock_queue;	599	our @unblock_queue;
468	our $UNBLOCK_POOL_SIZE = 2;
469		600
470	sub unblock_handler_ {	601	# we create a special coro because we want to cede,
471	while () {	602	# to reduce pressure on the coro pool (because most callbacks
472	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	603	# return immediately and can be reused) and because we cannot cede
473	$cb->(@arg);	604	# inside an event callback.
474
475	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
476	push @unblock_pool, $Coro::current;
477	schedule;
478	}
479	}
480
481	our $unblock_scheduler = async {	605	our $unblock_scheduler = new Coro sub {
482	while () {	606	while () {
483	while (my $cb = pop @unblock_queue) {	607	while (my $cb = pop @unblock_queue) {
484	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	608	&async_pool (@$cb);
485	$handler->{arg} = $cb;	609
486	$handler->ready;	610	# for short-lived callbacks, this reduces pressure on the coro pool
		611	# as the chance is very high that the async_poll coro will be back
		612	# in the idle state when cede returns
487	cede;	613	cede;
488	}	614	}
489		615	schedule; # sleep well
490	schedule;
491	}	616	}
492	};	617	};
		618	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
493		619
494	sub unblock_sub(&) {	620	sub unblock_sub(&) {
495	my $cb = shift;	621	my $cb = shift;
496		622
497	sub {	623	sub {
498	push @unblock_queue, [$cb, @_];	624	unshift @unblock_queue, [$cb, @_];
499	$unblock_scheduler->ready;	625	$unblock_scheduler->ready;
500	}	626	}
501	}	627	}
502		628
		629	=item $cb = Coro::rouse_cb
		630
		631	Create and return a "rouse callback". That's a code reference that, when
		632	called, will save its arguments and notify the owner coroutine of the
		633	callback.
		634
		635	See the next function.
		636
		637	=item @args = Coro::rouse_wait [$cb]
		638
		639	Wait for the specified rouse callback (or the last one tht was created in
		640	this coroutine).
		641
		642	As soon as the callback is invoked (or when the calback was invoked before
		643	C<rouse_wait>), it will return a copy of the arguments originally passed
		644	to the rouse callback.
		645
		646	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		647
503	=back	648	=back
504		649
505	=cut	650	=cut
506		651
507	1;	652	1;
508		653
		654	=head1 HOW TO WAIT FOR A CALLBACK
		655
		656	It is very common for a coroutine to wait for some callback to be
		657	called. This occurs naturally when you use coroutines in an otherwise
		658	event-based program, or when you use event-based libraries.
		659
		660	These typically register a callback for some event, and call that callback
		661	when the event occured. In a coroutine, however, you typically want to
		662	just wait for the event, simplyifying things.
		663
		664	For example C<< AnyEvent->child >> registers a callback to be called when
		665	a specific child has exited:
		666
		667	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		668
		669	But from withina coroutine, you often just want to write this:
		670
		671	my $status = wait_for_child $pid;
		672
		673	Coro offers two functions specifically designed to make this easy,
		674	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		675
		676	The first function, C<rouse_cb>, generates and returns a callback that,
		677	when invoked, will save it's arguments and notify the coroutine that
		678	created the callback.
		679
		680	The second function, C<rouse_wait>, waits for the callback to be called
		681	(by calling C<schedule> to go to sleep) and returns the arguments
		682	originally passed to the callback.
		683
		684	Using these functions, it becomes easy to write the C<wait_for_child>
		685	function mentioned above:
		686
		687	sub wait_for_child($) {
		688	my ($pid) = @_;
		689
		690	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		691
		692	my ($rpid, $rstatus) = Coro::rouse_wait;
		693	$rstatus
		694	}
		695
		696	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		697	you can roll your own, using C<schedule>:
		698
		699	sub wait_for_child($) {
		700	my ($pid) = @_;
		701
		702	# store the current coroutine in $current,
		703	# and provide result variables for the closure passed to ->child
		704	my $current = $Coro::current;
		705	my ($done, $rstatus);
		706
		707	# pass a closure to ->child
		708	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		709	$rstatus = $_[1]; # remember rstatus
		710	$done = 1; # mark $rstatus as valud
		711	});
		712
		713	# wait until the closure has been called
		714	schedule while !$done;
		715
		716	$rstatus
		717	}
		718
		719
509	=head1 BUGS/LIMITATIONS	720	=head1 BUGS/LIMITATIONS
510		721
511	- you must make very sure that no coro is still active on global	722	=over 4
512	destruction. very bad things might happen otherwise (usually segfaults).
513		723
		724	=item fork with pthread backend
		725
		726	When Coro is compiled using the pthread backend (which isn't recommended
		727	but required on many BSDs as their libcs are completely broken), then
		728	coroutines will not survive a fork. There is no known workaround except to
		729	fix your libc and use a saner backend.
		730
		731	=item perl process emulation ("threads")
		732
514	- this module is not thread-safe. You should only ever use this module	733	This module is not perl-pseudo-thread-safe. You should only ever use this
515	from the same thread (this requirement might be losened in the future	734	module from the same thread (this requirement might be removed in the
516	to allow per-thread schedulers, but Coro::State does not yet allow	735	future to allow per-thread schedulers, but Coro::State does not yet allow
517	this).	736	this). I recommend disabling thread support and using processes, as having
		737	the windows process emulation enabled under unix roughly halves perl
		738	performance, even when not used.
		739
		740	=item coroutine switching not signal safe
		741
		742	You must not switch to another coroutine from within a signal handler
		743	(only relevant with %SIG - most event libraries provide safe signals).
		744
		745	That means you I<MUST NOT> call any function that might "block" the
		746	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		747	anything that calls those. Everything else, including calling C<ready>,
		748	works.
		749
		750	=back
		751
518		752
519	=head1 SEE ALSO	753	=head1 SEE ALSO
520		754
		755	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		756
		757	Debugging: L<Coro::Debug>.
		758
521	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	759	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
522		760
523	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	761	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
524		762
525	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	763	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
526		764
527	Embedding: L<Coro:MakeMaker>	765	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		766
		767	XS API: L<Coro::MakeMaker>.
		768
		769	Low level Configuration, Coroutine Environment: L<Coro::State>.
528		770
529	=head1 AUTHOR	771	=head1 AUTHOR
530		772
531	Marc Lehmann <schmorp@schmorp.de>	773	Marc Lehmann <schmorp@schmorp.de>
532	http://home.schmorp.de/	774	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC vs. Revision 1.234 by root, Fri Nov 21 06:52:10 2008 UTC

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Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC vs.
Revision 1.234 by root, Fri Nov 21 06:52:10 2008 UTC