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

Comparing Coro/Coro.pm (file contents):
Revision 1.99 by root, Tue Dec 5 12:50:04 2006 UTC vs.
Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only 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 use din this module also
26	guarentees 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 continuations in general, most often
32	very slow and memory-intensive emulation of processes using threads. This	35	in the form of cooperative threads (also called coroutines in the
33	is a performance win on Windows machines, and a loss everywhere else).	36	documentation). They are similar to kernel threads but don't (in general)
		37	run in parallel at the same time even on SMP machines. The specific flavor
		38	of thread offered by this module also guarantees you that it will not
		39	switch between threads unless necessary, at easily-identified points in
		40	your program, so locking and parallel access are rarely an issue, making
		41	thread programming much safer and easier than using other thread 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 threads
		46	very easy. And threads 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 thread is defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	57	@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,
37	its own set of lexicals and its own set of perls most important global	58	its own set of lexicals and its own set of perls most important global
38	variables.	59	variables (see L<Coro::State> for more configuration and background info).
		60
		61	See also the C<SEE ALSO> section at the end of this document - the Coro
		62	module family is quite large.
39		63
40	=cut	64	=cut
41		65
42	package Coro;	66	package Coro;
43		67
44	use strict;	68	use strict qw(vars subs);
45	no warnings "uninitialized";	69	no warnings "uninitialized";
		70
		71	use Guard ();
46		72
47	use Coro::State;	73	use Coro::State;
48		74
49	use base qw(Coro::State Exporter);	75	use base qw(Coro::State Exporter);
50		76
51	our $idle; # idle handler	77	our $idle; # idle handler
52	our $main; # main coroutine	78	our $main; # main coroutine
53	our $current; # current coroutine	79	our $current; # current coroutine
54		80
55	our $VERSION = '3.11';	81	our $VERSION = 5.13;
56		82
57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	83	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	84	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	85	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	86	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	87	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		88
63	{	89	=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		90
97	=over 4	91	=over 4
98		92
99	=item $main	93	=item $Coro::main
100		94
101	This coroutine represents the main program.	95	This variable stores the coroutine object that represents the main
		96	program. While you cna C<ready> it and do most other things you can do to
		97	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		98	whether you are running in the main program or not.
102		99
103	=cut	100	=cut
104		101
105	$main = new Coro;	102	# $main is now being initialised by Coro::State
106		103
107	=item $current (or as function: current)	104	=item $Coro::current
108		105
109	The current coroutine (the last coroutine switched to). The initial value	106	The coroutine object representing the current coroutine (the last
		107	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	108	C<$Coro::main> (of course).
111		109
112	This variable is B<strictly> I<read-only>. It is provided for performance	110	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	111	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	112	not otherwise modify the variable itself.
115		113
116	=cut	114	=cut
117		115
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 }	116	sub current() { $current } # [DEPRECATED]
125		117
126	=item $idle	118	=item $Coro::idle
127		119
		120	This variable is mainly useful to integrate Coro into event loops. It is
		121	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		122	pretty low-level functionality.
		123
		124	This variable stores either a coroutine or a callback.
		125
128	A callback that is called whenever the scheduler finds no ready coroutines	126	If it is a callback, the it is called whenever the scheduler finds no
129	to run. The default implementation prints "FATAL: deadlock detected" and	127	ready coroutines to run. The default implementation prints "FATAL:
130	exits, because the program has no other way to continue.	128	deadlock detected" and exits, because the program has no other way to
		129	continue.
131		130
		131	If it is a coroutine object, then this object will be readied (without
		132	invoking any ready hooks, however) when the scheduler finds no other ready
		133	coroutines to run.
		134
132	This hook is overwritten by modules such as C<Coro::Timer> and	135	This hook is overwritten by modules such as C<Coro::EV> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a	136	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.	137	coroutine so the scheduler can run it.
135		138
		139	Note that the callback I<must not>, under any circumstances, block
		140	the current coroutine. Normally, this is achieved by having an "idle
		141	coroutine" that calls the event loop and then blocks again, and then
		142	readying that coroutine in the idle handler, or by simply placing the idle
		143	coroutine in this variable.
		144
		145	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		146	technique.
		147
136	Please note that if your callback recursively invokes perl (e.g. for event	148	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.	149	handlers), then it must be prepared to be called recursively itself.
138		150
139	=cut	151	=cut
140		152
141	$idle = sub {	153	$idle = sub {
142	require Carp;	154	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	155	Carp::croak ("FATAL: deadlock detected");
144	};	156	};
145		157
146	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
147	# cannot destroy itself.	159	# cannot destroy itself.
148	my @destroy;	160	our @destroy;
		161	our $manager;
		162
149	my $manager; $manager = new Coro sub {	163	$manager = new Coro sub {
150	while () {	164	while () {
151	# by overwriting the state object with the manager we destroy it	165	Coro::_cancel shift @destroy
152	# while still being able to schedule this coroutine (in case it has
153	# been readied multiple times. this is harmless since the manager
154	# can be called as many times as neccessary and will always
155	# remove itself from the runqueue
156	while (@destroy) {	166	while @destroy;
157	my $coro = pop @destroy;
158	$coro->{status} \|\|= [];
159	$_->ready for @{delete $coro->{join} \|\| []};
160		167
161	# the next line destroys the coro state, but keeps the
162	# coroutine itself intact (we basically make it a zombie
163	# coroutine that always runs the manager thread, so it's possible
164	# to transfer() to this coroutine).
165	$coro->_clone_state_from ($manager);
166	}
167	&schedule;	168	&schedule;
168	}	169	}
169	};	170	};
170		171	$manager->{desc} = "[coro manager]";
171	# static methods. not really.	172	$manager->prio (PRIO_MAX);
172		173
173	=back	174	=back
174		175
175	=head2 STATIC METHODS	176	=head1 SIMPLE COROUTINE CREATION
176
177	Static methods are actually functions that operate on the current coroutine only.
178		177
179	=over 4	178	=over 4
180		179
181	=item async { ... } [@args...]	180	=item async { ... } [@args...]
182		181
183	Create a new asynchronous coroutine and return it's coroutine object	182	Create a new coroutine and return its coroutine object (usually
184	(usually unused). When the sub returns the new coroutine is automatically	183	unused). The coroutine will be put into the ready queue, so
		184	it will start running automatically on the next scheduler run.
		185
		186	The first argument is a codeblock/closure that should be executed in the
		187	coroutine. When it returns argument returns the coroutine is automatically
185	terminated.	188	terminated.
186		189
187	Calling C<exit> in a coroutine will not work correctly, so do not do that.	190	The remaining arguments are passed as arguments to the closure.
188		191
189	When the coroutine dies, the program will exit, just as in the main	192	See the C<Coro::State::new> constructor for info about the coroutine
190	program.	193	environment in which coroutines are executed.
191		194
		195	Calling C<exit> in a coroutine will do the same as calling exit outside
		196	the coroutine. Likewise, when the coroutine dies, the program will exit,
		197	just as it would in the main program.
		198
		199	If you do not want that, you can provide a default C<die> handler, or
		200	simply avoid dieing (by use of C<eval>).
		201
192	# create a new coroutine that just prints its arguments	202	Example: Create a new coroutine that just prints its arguments.
		203
193	async {	204	async {
194	print "@_\n";	205	print "@_\n";
195	} 1,2,3,4;	206	} 1,2,3,4;
196		207
197	=cut	208	=cut
198		209
199	sub async(&@) {	210	sub async(&@) {
200	my $pid = new Coro @_;	211	my $coro = new Coro @_;
201	$pid->ready;	212	$coro->ready;
202	$pid	213	$coro
203	}	214	}
		215
		216	=item async_pool { ... } [@args...]
		217
		218	Similar to C<async>, but uses a coroutine pool, so you should not call
		219	terminate or join on it (although you are allowed to), and you get a
		220	coroutine that might have executed other code already (which can be good
		221	or bad :).
		222
		223	On the plus side, this function is about twice as fast as creating (and
		224	destroying) a completely new coroutine, so if you need a lot of generic
		225	coroutines in quick successsion, use C<async_pool>, not C<async>.
		226
		227	The code block is executed in an C<eval> context and a warning will be
		228	issued in case of an exception instead of terminating the program, as
		229	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		230	will not work in the expected way, unless you call terminate or cancel,
		231	which somehow defeats the purpose of pooling (but is fine in the
		232	exceptional case).
		233
		234	The priority will be reset to C<0> after each run, tracing will be
		235	disabled, the description will be reset and the default output filehandle
		236	gets restored, so you can change all these. Otherwise the coroutine will
		237	be re-used "as-is": most notably if you change other per-coroutine global
		238	stuff such as C<$/> you I<must needs> revert that change, which is most
		239	simply done by using local as in: C<< local $/ >>.
		240
		241	The idle pool size is limited to C<8> idle coroutines (this can be
		242	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
		243	coros as required.
		244
		245	If you are concerned about pooled coroutines growing a lot because a
		246	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		247	{ terminate }> once per second or so to slowly replenish the pool. In
		248	addition to that, when the stacks used by a handler grows larger than 32kb
		249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		250
		251	=cut
		252
		253	our $POOL_SIZE = 8;
		254	our $POOL_RSS = 32 * 1024;
		255	our @async_pool;
		256
		257	sub pool_handler {
		258	while () {
		259	eval {
		260	&{&_pool_handler} while 1;
		261	};
		262
		263	warn $@ if $@;
		264	}
		265	}
		266
		267	=back
		268
		269	=head1 STATIC METHODS
		270
		271	Static methods are actually functions that implicitly operate on the
		272	current coroutine.
		273
		274	=over 4
204		275
205	=item schedule	276	=item schedule
206		277
207	Calls the scheduler. Please note that the current coroutine will not be put	278	Calls the scheduler. The scheduler will find the next coroutine that is
		279	to be run from the ready queue and switches to it. The next coroutine
		280	to be run is simply the one with the highest priority that is longest
		281	in its ready queue. If there is no coroutine ready, it will clal the
		282	C<$Coro::idle> hook.
		283
		284	Please note that the current coroutine will I<not> be put into the ready
208	into the ready queue, so calling this function usually means you will	285	queue, so calling this function usually means you will never be called
209	never be called again unless something else (e.g. an event handler) calls	286	again unless something else (e.g. an event handler) calls C<< ->ready >>,
210	ready.	287	thus waking you up.
211		288
212	The canonical way to wait on external events is this:	289	This makes C<schedule> I<the> generic method to use to block the current
		290	coroutine and wait for events: first you remember the current coroutine in
		291	a variable, then arrange for some callback of yours to call C<< ->ready
		292	>> on that once some event happens, and last you call C<schedule> to put
		293	yourself to sleep. Note that a lot of things can wake your coroutine up,
		294	so you need to check whether the event indeed happened, e.g. by storing the
		295	status in a variable.
213		296
		297	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		298
		299	=item cede
		300
		301	"Cede" to other coroutines. This function puts the current coroutine into
		302	the ready queue and calls C<schedule>, which has the effect of giving
		303	up the current "timeslice" to other coroutines of the same or higher
		304	priority. Once your coroutine gets its turn again it will automatically be
		305	resumed.
		306
		307	This function is often called C<yield> in other languages.
		308
		309	=item Coro::cede_notself
		310
		311	Works like cede, but is not exported by default and will cede to I<any>
		312	coroutine, regardless of priority. This is useful sometimes to ensure
		313	progress is made.
		314
		315	=item terminate [arg...]
		316
		317	Terminates the current coroutine with the given status values (see L<cancel>).
		318
		319	=item killall
		320
		321	Kills/terminates/cancels all coroutines except the currently running
		322	one. This can be useful after a fork, either in the child or the parent,
		323	as usually only one of them should inherit the running coroutines.
		324
		325	Note that in the implementation, destructors run as normal, making this
		326	function not so useful after a fork. Future versions of this function
		327	might try to free resources without running any code.
		328
		329	Note that while this will try to free some of the main programs resources,
		330	you cannot free all of them, so if a coroutine that is not the main
		331	program calls this function, there will be some one-time resource leak.
		332
		333	=cut
		334
		335	sub killall {
		336	for (Coro::State::list) {
		337	$_->cancel
		338	if $_ != $current && UNIVERSAL::isa $_, "Coro";
214	{	339	}
215	# remember current coroutine	340	}
		341
		342	=back
		343
		344	=head1 COROUTINE OBJECT METHODS
		345
		346	These are the methods you can call on coroutine objects (or to create
		347	them).
		348
		349	=over 4
		350
		351	=item new Coro \&sub [, @args...]
		352
		353	Create a new coroutine and return it. When the sub returns, the coroutine
		354	automatically terminates as if C<terminate> with the returned values were
		355	called. To make the coroutine run you must first put it into the ready
		356	queue by calling the ready method.
		357
		358	See C<async> and C<Coro::State::new> for additional info about the
		359	coroutine environment.
		360
		361	=cut
		362
		363	sub _coro_run {
		364	terminate &{+shift};
		365	}
		366
		367	=item $success = $coroutine->ready
		368
		369	Put the given coroutine into the end of its ready queue (there is one
		370	queue for each priority) and return true. If the coroutine is already in
		371	the ready queue, do nothing and return false.
		372
		373	This ensures that the scheduler will resume this coroutine automatically
		374	once all the coroutines of higher priority and all coroutines of the same
		375	priority that were put into the ready queue earlier have been resumed.
		376
		377	=item $is_ready = $coroutine->is_ready
		378
		379	Return whether the coroutine is currently the ready queue or not,
		380
		381	=item $coroutine->cancel (arg...)
		382
		383	Terminates the given coroutine and makes it return the given arguments as
		384	status (default: the empty list). Never returns if the coroutine is the
		385	current coroutine.
		386
		387	=cut
		388
		389	sub cancel {
		390	my $self = shift;
		391
		392	if ($current == $self) {
		393	terminate @_;
		394	} else {
		395	$self->{_status} = [@_];
		396	$self->_cancel;
		397	}
		398	}
		399
		400	=item $coroutine->schedule_to
		401
		402	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		403	of continuing with the next coro from the ready queue, always switch to
		404	the given coroutine object (regardless of priority etc.). The readyness
		405	state of that coroutine isn't changed.
		406
		407	This is an advanced method for special cases - I'd love to hear about any
		408	uses for this one.
		409
		410	=item $coroutine->cede_to
		411
		412	Like C<schedule_to>, but puts the current coroutine into the ready
		413	queue. This has the effect of temporarily switching to the given
		414	coroutine, and continuing some time later.
		415
		416	This is an advanced method for special cases - I'd love to hear about any
		417	uses for this one.
		418
		419	=item $coroutine->throw ([$scalar])
		420
		421	If C<$throw> is specified and defined, it will be thrown as an exception
		422	inside the coroutine at the next convenient point in time. Otherwise
		423	clears the exception object.
		424
		425	Coro will check for the exception each time a schedule-like-function
		426	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		427	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		428	detect this case and return early in case an exception is pending.
		429
		430	The exception object will be thrown "as is" with the specified scalar in
		431	C<$@>, i.e. if it is a string, no line number or newline will be appended
		432	(unlike with C<die>).
		433
		434	This can be used as a softer means than C<cancel> to ask a coroutine to
		435	end itself, although there is no guarantee that the exception will lead to
		436	termination, and if the exception isn't caught it might well end the whole
		437	program.
		438
		439	You might also think of C<throw> as being the moral equivalent of
		440	C<kill>ing a coroutine with a signal (in this case, a scalar).
		441
		442	=item $coroutine->join
		443
		444	Wait until the coroutine terminates and return any values given to the
		445	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		446	from multiple coroutines, and all will be resumed and given the status
		447	return once the C<$coroutine> terminates.
		448
		449	=cut
		450
		451	sub join {
		452	my $self = shift;
		453
		454	unless ($self->{_status}) {
216	my $current = $Coro::current;	455	my $current = $current;
217		456
218	# register a hypothetical event handler	457	push @{$self->{_on_destroy}}, sub {
219	on_event_invoke sub {
220	# wake up sleeping coroutine
221	$current->ready;	458	$current->ready;
222	undef $current;	459	undef $current;
223	};	460	};
224		461
225	# call schedule until event occured.
226	# in case we are woken up for other reasons
227	# (current still defined), loop.
228	Coro::schedule while $current;	462	&schedule while $current;
229	}	463	}
230		464
231	=item cede
232
233	"Cede" to other coroutines. This function puts the current coroutine into the
234	ready queue and calls C<schedule>, which has the effect of giving up the
235	current "timeslice" to other coroutines of the same or higher priority.
236
237	=item terminate [arg...]
238
239	Terminates the current coroutine with the given status values (see L<cancel>).
240
241	=cut
242
243	sub terminate {
244	$current->cancel (@_);
245	}
246
247	=back
248
249	# dynamic methods
250
251	=head2 COROUTINE METHODS
252
253	These are the methods you can call on coroutine objects.
254
255	=over 4
256
257	=item new Coro \&sub [, @args...]
258
259	Create a new coroutine and return it. When the sub returns the coroutine
260	automatically terminates as if C<terminate> with the returned values were
261	called. To make the coroutine run you must first put it into the ready queue
262	by calling the ready method.
263
264	Calling C<exit> in a coroutine will not work correctly, so do not do that.
265
266	=cut
267
268	sub _run_coro {
269	terminate &{+shift};
270	}
271
272	sub new {
273	my $class = shift;
274
275	$class->SUPER::new (\&_run_coro, @_)
276	}
277
278	=item $success = $coroutine->ready
279
280	Put the given coroutine into the ready queue (according to it's priority)
281	and return true. If the coroutine is already in the ready queue, do nothing
282	and return false.
283
284	=item $is_ready = $coroutine->is_ready
285
286	Return wether the coroutine is currently the ready queue or not,
287
288	=item $coroutine->cancel (arg...)
289
290	Terminates the given coroutine and makes it return the given arguments as
291	status (default: the empty list).
292
293	=cut
294
295	sub cancel {
296	my $self = shift;
297	$self->{status} = [@_];
298	push @destroy, $self;
299	$manager->ready;
300	&schedule if $current == $self;
301	}
302
303	=item $coroutine->join
304
305	Wait until the coroutine terminates and return any values given to the
306	C<terminate> or C<cancel> functions. C<join> can be called multiple times
307	from multiple coroutine.
308
309	=cut
310
311	sub join {
312	my $self = shift;
313	unless ($self->{status}) {
314	push @{$self->{join}}, $current;
315	&schedule;
316	}
317	wantarray ? @{$self->{status}} : $self->{status}[0];	465	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		466	}
		467
		468	=item $coroutine->on_destroy (\&cb)
		469
		470	Registers a callback that is called when this coroutine gets destroyed,
		471	but before it is joined. The callback gets passed the terminate arguments,
		472	if any, and I<must not> die, under any circumstances.
		473
		474	=cut
		475
		476	sub on_destroy {
		477	my ($self, $cb) = @_;
		478
		479	push @{ $self->{_on_destroy} }, $cb;
318	}	480	}
319		481
320	=item $oldprio = $coroutine->prio ($newprio)	482	=item $oldprio = $coroutine->prio ($newprio)
321		483
322	Sets (or gets, if the argument is missing) the priority of the	484	Sets (or gets, if the argument is missing) the priority of the
345	higher values mean lower priority, just as in unix).	507	higher values mean lower priority, just as in unix).
346		508
347	=item $olddesc = $coroutine->desc ($newdesc)	509	=item $olddesc = $coroutine->desc ($newdesc)
348		510
349	Sets (or gets in case the argument is missing) the description for this	511	Sets (or gets in case the argument is missing) the description for this
350	coroutine. This is just a free-form string you can associate with a coroutine.	512	coroutine. This is just a free-form string you can associate with a
		513	coroutine.
		514
		515	This method simply sets the C<< $coroutine->{desc} >> member to the given
		516	string. You can modify this member directly if you wish.
351		517
352	=cut	518	=cut
353		519
354	sub desc {	520	sub desc {
355	my $old = $_[0]{desc};	521	my $old = $_[0]{desc};
356	$_[0]{desc} = $_[1] if @_ > 1;	522	$_[0]{desc} = $_[1] if @_ > 1;
357	$old;	523	$old;
358	}	524	}
359		525
		526	sub transfer {
		527	require Carp;
		528	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		529	}
		530
360	=back	531	=back
361		532
362	=head2 GLOBAL FUNCTIONS	533	=head1 GLOBAL FUNCTIONS
363		534
364	=over 4	535	=over 4
365		536
366	=item Coro::nready	537	=item Coro::nready
367		538
368	Returns the number of coroutines that are currently in the ready state,	539	Returns the number of coroutines that are currently in the ready state,
369	i.e. that can be swicthed to. The value C<0> means that the only runnable	540	i.e. that can be switched to by calling C<schedule> directory or
		541	indirectly. The value C<0> means that the only runnable coroutine is the
370	coroutine is the currently running one, so C<cede> would have no effect,	542	currently running one, so C<cede> would have no effect, and C<schedule>
371	and C<schedule> would cause a deadlock unless there is an idle handler	543	would cause a deadlock unless there is an idle handler that wakes up some
372	that wakes up some coroutines.	544	coroutines.
		545
		546	=item my $guard = Coro::guard { ... }
		547
		548	This function still exists, but is deprecated. Please use the
		549	C<Guard::guard> function instead.
		550
		551	=cut
		552
		553	BEGIN { *guard = \&Guard::guard }
373		554
374	=item unblock_sub { ... }	555	=item unblock_sub { ... }
375		556
376	This utility function takes a BLOCK or code reference and "unblocks" it,	557	This utility function takes a BLOCK or code reference and "unblocks" it,
377	returning the new coderef. This means that the new coderef will return	558	returning a new coderef. Unblocking means that calling the new coderef
378	immediately without blocking, returning nothing, while the original code	559	will return immediately without blocking, returning nothing, while the
379	ref will be called (with parameters) from within its own coroutine.	560	original code ref will be called (with parameters) from within another
		561	coroutine.
380		562
381	The reason this fucntion exists is that many event libraries (such as the	563	The reason this function exists is that many event libraries (such as the
382	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	564	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
383	of thread-safety). This means you must not block within event callbacks,	565	of reentrancy). This means you must not block within event callbacks,
384	otherwise you might suffer from crashes or worse.	566	otherwise you might suffer from crashes or worse. The only event library
		567	currently known that is safe to use without C<unblock_sub> is L<EV>.
385		568
386	This function allows your callbacks to block by executing them in another	569	This function allows your callbacks to block by executing them in another
387	coroutine where it is safe to block. One example where blocking is handy	570	coroutine where it is safe to block. One example where blocking is handy
388	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	571	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
389	disk.	572	disk, for example.
390		573
391	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	574	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
392	creating event callbacks that want to block.	575	creating event callbacks that want to block.
393		576
394	=cut	577	If your handler does not plan to block (e.g. simply sends a message to
		578	another coroutine, or puts some other coroutine into the ready queue),
		579	there is no reason to use C<unblock_sub>.
395		580
396	our @unblock_pool;	581	Note that you also need to use C<unblock_sub> for any other callbacks that
		582	are indirectly executed by any C-based event loop. For example, when you
		583	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		584	provides callbacks that are the result of some event callback, then you
		585	must not block either, or use C<unblock_sub>.
		586
		587	=cut
		588
397	our @unblock_queue;	589	our @unblock_queue;
398	our $UNBLOCK_POOL_SIZE = 2;
399		590
400	sub unblock_handler_ {	591	# we create a special coro because we want to cede,
401	while () {	592	# to reduce pressure on the coro pool (because most callbacks
402	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	593	# return immediately and can be reused) and because we cannot cede
403	$cb->(@arg);	594	# inside an event callback.
404
405	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
406	push @unblock_pool, $Coro::current;
407	schedule;
408	}
409	}
410
411	our $unblock_scheduler = async {	595	our $unblock_scheduler = new Coro sub {
412	while () {	596	while () {
413	while (my $cb = pop @unblock_queue) {	597	while (my $cb = pop @unblock_queue) {
414	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	598	&async_pool (@$cb);
415	$handler->{arg} = $cb;	599
416	$handler->ready;	600	# for short-lived callbacks, this reduces pressure on the coro pool
		601	# as the chance is very high that the async_poll coro will be back
		602	# in the idle state when cede returns
417	cede;	603	cede;
418	}	604	}
419		605	schedule; # sleep well
420	schedule;
421	}	606	}
422	};	607	};
		608	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
423		609
424	sub unblock_sub(&) {	610	sub unblock_sub(&) {
425	my $cb = shift;	611	my $cb = shift;
426		612
427	sub {	613	sub {
428	push @unblock_queue, [$cb, @_];	614	unshift @unblock_queue, [$cb, @_];
429	$unblock_scheduler->ready;	615	$unblock_scheduler->ready;
430	}	616	}
431	}	617	}
432		618
		619	=item $cb = Coro::rouse_cb
		620
		621	Create and return a "rouse callback". That's a code reference that,
		622	when called, will remember a copy of its arguments and notify the owner
		623	coroutine of the callback.
		624
		625	See the next function.
		626
		627	=item @args = Coro::rouse_wait [$cb]
		628
		629	Wait for the specified rouse callback (or the last one that was created in
		630	this coroutine).
		631
		632	As soon as the callback is invoked (or when the callback was invoked
		633	before C<rouse_wait>), it will return the arguments originally passed to
		634	the rouse callback.
		635
		636	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		637
433	=back	638	=back
434		639
435	=cut	640	=cut
436		641
437	1;	642	1;
438		643
		644	=head1 HOW TO WAIT FOR A CALLBACK
		645
		646	It is very common for a coroutine to wait for some callback to be
		647	called. This occurs naturally when you use coroutines in an otherwise
		648	event-based program, or when you use event-based libraries.
		649
		650	These typically register a callback for some event, and call that callback
		651	when the event occured. In a coroutine, however, you typically want to
		652	just wait for the event, simplyifying things.
		653
		654	For example C<< AnyEvent->child >> registers a callback to be called when
		655	a specific child has exited:
		656
		657	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		658
		659	But from withina coroutine, you often just want to write this:
		660
		661	my $status = wait_for_child $pid;
		662
		663	Coro offers two functions specifically designed to make this easy,
		664	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		665
		666	The first function, C<rouse_cb>, generates and returns a callback that,
		667	when invoked, will save its arguments and notify the coroutine that
		668	created the callback.
		669
		670	The second function, C<rouse_wait>, waits for the callback to be called
		671	(by calling C<schedule> to go to sleep) and returns the arguments
		672	originally passed to the callback.
		673
		674	Using these functions, it becomes easy to write the C<wait_for_child>
		675	function mentioned above:
		676
		677	sub wait_for_child($) {
		678	my ($pid) = @_;
		679
		680	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		681
		682	my ($rpid, $rstatus) = Coro::rouse_wait;
		683	$rstatus
		684	}
		685
		686	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		687	you can roll your own, using C<schedule>:
		688
		689	sub wait_for_child($) {
		690	my ($pid) = @_;
		691
		692	# store the current coroutine in $current,
		693	# and provide result variables for the closure passed to ->child
		694	my $current = $Coro::current;
		695	my ($done, $rstatus);
		696
		697	# pass a closure to ->child
		698	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		699	$rstatus = $_[1]; # remember rstatus
		700	$done = 1; # mark $rstatus as valud
		701	});
		702
		703	# wait until the closure has been called
		704	schedule while !$done;
		705
		706	$rstatus
		707	}
		708
		709
439	=head1 BUGS/LIMITATIONS	710	=head1 BUGS/LIMITATIONS
440		711
441	- you must make very sure that no coro is still active on global	712	=over 4
442	destruction. very bad things might happen otherwise (usually segfaults).
443		713
		714	=item fork with pthread backend
		715
		716	When Coro is compiled using the pthread backend (which isn't recommended
		717	but required on many BSDs as their libcs are completely broken), then
		718	coroutines will not survive a fork. There is no known workaround except to
		719	fix your libc and use a saner backend.
		720
		721	=item perl process emulation ("threads")
		722
444	- this module is not thread-safe. You should only ever use this module	723	This module is not perl-pseudo-thread-safe. You should only ever use this
445	from the same thread (this requirement might be losened in the future	724	module from the first thread (this requirement might be removed in the
446	to allow per-thread schedulers, but Coro::State does not yet allow	725	future to allow per-thread schedulers, but Coro::State does not yet allow
447	this).	726	this). I recommend disabling thread support and using processes, as having
		727	the windows process emulation enabled under unix roughly halves perl
		728	performance, even when not used.
		729
		730	=item coroutine switching not signal safe
		731
		732	You must not switch to another coroutine from within a signal handler
		733	(only relevant with %SIG - most event libraries provide safe signals).
		734
		735	That means you I<MUST NOT> call any function that might "block" the
		736	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		737	anything that calls those. Everything else, including calling C<ready>,
		738	works.
		739
		740	=back
		741
448		742
449	=head1 SEE ALSO	743	=head1 SEE ALSO
450		744
		745	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		746
		747	Debugging: L<Coro::Debug>.
		748
451	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	749	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
452		750
453	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	751	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		752	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
454		753
455	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	754	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
456		755
457	Embedding: L<Coro:MakeMaker>	756	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		757	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		758	L<Coro::Select>.
		759
		760	XS API: L<Coro::MakeMaker>.
		761
		762	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
458		763
459	=head1 AUTHOR	764	=head1 AUTHOR
460		765
461	Marc Lehmann <schmorp@schmorp.de>	766	Marc Lehmann <schmorp@schmorp.de>
462	http://home.schmorp.de/	767	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.99 by root, Tue Dec 5 12:50:04 2006 UTC vs. Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.99 by root, Tue Dec 5 12:50:04 2006 UTC vs.
Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC