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Comparing Coro/Coro.pm (file contents):
Revision 1.145 by root, Wed Oct 3 16:03:17 2007 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 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 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 = '4.0';	81	our $VERSION = 5.13;
56		82
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	83	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	84	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	85	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	86	);
61	our @EXPORT_OK = (@{$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 essential 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	$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 }	116	sub current() { $current } # [DEPRECATED]
127		117
128	=item $idle	118	=item $Coro::idle
129		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
130	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
131	to run. The default implementation prints "FATAL: deadlock detected" and	127	ready coroutines to run. The default implementation prints "FATAL:
132	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.
133		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
134	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
135	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
136	coroutine so the scheduler can run it.	137	coroutine so the scheduler can run it.
137		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
138	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
139	handlers), then it must be prepared to be called recursively.	149	handlers), then it must be prepared to be called recursively itself.
140		150
141	=cut	151	=cut
142		152
143	$idle = sub {	153	$idle = sub {
144	require Carp;	154	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	155	Carp::croak ("FATAL: deadlock detected");
146	};	156	};
147		157
148	sub _cancel {
149	my ($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->{_on_destroy}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
161	# cannot destroy itself.	159	# cannot destroy itself.
162	my @destroy;	160	our @destroy;
163	my $manager;	161	our $manager;
164		162
165	$manager = new Coro sub {	163	$manager = new Coro sub {
166	while () {	164	while () {
167	(shift @destroy)->_cancel	165	Coro::_cancel shift @destroy
168	while @destroy;	166	while @destroy;
169		167
170	&schedule;	168	&schedule;
171	}	169	}
172	};	170	};
173	$manager->desc ("[coro manager]");	171	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	172	$manager->prio (PRIO_MAX);
175		173
176	# static methods. not really.
177
178	=back	174	=back
179		175
180	=head2 STATIC METHODS	176	=head1 SIMPLE COROUTINE CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		177
184	=over 4	178	=over 4
185		179
186	=item async { ... } [@args...]	180	=item async { ... } [@args...]
187		181
188	Create a new asynchronous coroutine and return it's coroutine object	182	Create a new coroutine and return its coroutine object (usually
189	(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
190	terminated.	188	terminated.
191		189
		190	The remaining arguments are passed as arguments to the closure.
		191
192	See the C<Coro::State::new> constructor for info about the coroutine	192	See the C<Coro::State::new> constructor for info about the coroutine
193	environment.	193	environment in which coroutines are executed.
194		194
195	Calling C<exit> in a coroutine will do the same as calling exit outside	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,	196	the coroutine. Likewise, when the coroutine dies, the program will exit,
197	just as it would in the main program.	197	just as it would in the main program.
198		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
199	# create a new coroutine that just prints its arguments	202	Example: Create a new coroutine that just prints its arguments.
		203
200	async {	204	async {
201	print "@_\n";	205	print "@_\n";
202	} 1,2,3,4;	206	} 1,2,3,4;
203		207
204	=cut	208	=cut
210	}	214	}
211		215
212	=item async_pool { ... } [@args...]	216	=item async_pool { ... } [@args...]
213		217
214	Similar to C<async>, but uses a coroutine pool, so you should not call	218	Similar to C<async>, but uses a coroutine pool, so you should not call
215	terminate or join (although you are allowed to), and you get a coroutine	219	terminate or join on it (although you are allowed to), and you get a
216	that might have executed other code already (which can be good or bad :).	220	coroutine that might have executed other code already (which can be good
		221	or bad :).
217		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
218	Also, the block is executed in an C<eval> context and a warning will be	227	The code block is executed in an C<eval> context and a warning will be
219	issued in case of an exception instead of terminating the program, as	228	issued in case of an exception instead of terminating the program, as
220	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	229	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
221	will not work in the expected way, unless you call terminate or cancel,	230	will not work in the expected way, unless you call terminate or cancel,
222	which somehow defeats the purpose of pooling.	231	which somehow defeats the purpose of pooling (but is fine in the
		232	exceptional case).
223		233
224	The priority will be reset to C<0> after each job, otherwise the coroutine	234	The priority will be reset to C<0> after each run, tracing will be
225	will be re-used "as-is".	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 $/ >>.
226		240
227	The pool size is limited to 8 idle coroutines (this can be adjusted by	241	The idle pool size is limited to C<8> idle coroutines (this can be
228	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	242	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
229	required.	243	coros as required.
230		244
231	If you are concerned about pooled coroutines growing a lot because a	245	If you are concerned about pooled coroutines growing a lot because a
232	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	246	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
233	{ terminate }> once per second or so to slowly replenish the pool. In	247	{ terminate }> once per second or so to slowly replenish the pool. In
234	addition to that, when the stacks used by a handler grows larger than 16kb	248	addition to that, when the stacks used by a handler grows larger than 32kb
235	(adjustable with $Coro::POOL_RSS) it will also exit.	249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
236		250
237	=cut	251	=cut
238		252
239	our $POOL_SIZE = 8;	253	our $POOL_SIZE = 8;
240	our $POOL_RSS = 16 * 1024;	254	our $POOL_RSS = 32 * 1024;
241	our @async_pool;	255	our @async_pool;
242		256
243	sub pool_handler {	257	sub pool_handler {
244	my $cb;
245
246	while () {	258	while () {
247	eval {	259	eval {
248	while () {	260	&{&_pool_handler} while 1;
249	_pool_1 $cb;
250	&$cb;
251	_pool_2 $cb;
252	&schedule;
253	}
254	};	261	};
255		262
256	last if $@ eq "\3terminate\2\n";
257	warn $@ if $@;	263	warn $@ if $@;
258	}	264	}
259	}	265	}
260		266
261	sub async_pool(&@) {	267	=back
262	# this is also inlined into the unlock_scheduler
263	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
264		268
265	$coro->{_invoke} = [@_];	269	=head1 STATIC METHODS
266	$coro->ready;
267		270
268	$coro	271	Static methods are actually functions that implicitly operate on the
269	}	272	current coroutine.
		273
		274	=over 4
270		275
271	=item schedule	276	=item schedule
272		277
273	Calls the scheduler. Please note that the current coroutine will not be put	278	Calls the scheduler. The scheduler will find the next coroutine that is
		279	to be run from the ready queue and switches to it. The next coroutine
		280	to be run is simply the one with the highest priority that is longest
		281	in its ready queue. If there is no coroutine ready, it will clal the
		282	C<$Coro::idle> hook.
		283
		284	Please note that the current coroutine will I<not> be put into the ready
274	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
275	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 >>,
276	ready.	287	thus waking you up.
277		288
278	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.
279		296
280	{	297	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
281	# remember current coroutine
282	my $current = $Coro::current;
283
284	# register a hypothetical event handler
285	on_event_invoke sub {
286	# wake up sleeping coroutine
287	$current->ready;
288	undef $current;
289	};
290
291	# call schedule until event occurred.
292	# in case we are woken up for other reasons
293	# (current still defined), loop.
294	Coro::schedule while $current;
295	}
296		298
297	=item cede	299	=item cede
298		300
299	"Cede" to other coroutines. This function puts the current coroutine into the	301	"Cede" to other coroutines. This function puts the current coroutine into
300	ready queue and calls C<schedule>, which has the effect of giving up the	302	the ready queue and calls C<schedule>, which has the effect of giving
301	current "timeslice" to other coroutines of the same or higher priority.	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.
302		306
303	Returns true if at least one coroutine switch has happened.	307	This function is often called C<yield> in other languages.
304		308
305	=item Coro::cede_notself	309	=item Coro::cede_notself
306		310
307	Works like cede, but is not exported by default and will cede to any	311	Works like cede, but is not exported by default and will cede to I<any>
308	coroutine, regardless of priority, once.	312	coroutine, regardless of priority. This is useful sometimes to ensure
309		313	progress is made.
310	Returns true if at least one coroutine switch has happened.
311		314
312	=item terminate [arg...]	315	=item terminate [arg...]
313		316
314	Terminates the current coroutine with the given status values (see L<cancel>).	317	Terminates the current coroutine with the given status values (see L<cancel>).
315		318
316	=item killall	319	=item killall
317		320
318	Kills/terminates/cancels all coroutines except the currently running	321	Kills/terminates/cancels all coroutines except the currently running
319	one. This is useful after a fork, either in the child or the parent, as	322	one. This can be useful after a fork, either in the child or the parent,
320	usually only one of them should inherit the running coroutines.	323	as usually only one of them should inherit the running coroutines.
321		324
322	=cut	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.
323		328
324	sub terminate {	329	Note that while this will try to free some of the main programs resources,
325	$current->cancel (@_);	330	you cannot free all of them, so if a coroutine that is not the main
326	}	331	program calls this function, there will be some one-time resource leak.
		332
		333	=cut
327		334
328	sub killall {	335	sub killall {
329	for (Coro::State::list) {	336	for (Coro::State::list) {
330	$_->cancel	337	$_->cancel
331	if $_ != $current && UNIVERSAL::isa $_, "Coro";	338	if $_ != $current && UNIVERSAL::isa $_, "Coro";
332	}	339	}
333	}	340	}
334		341
335	=back	342	=back
336		343
337	# dynamic methods
338
339	=head2 COROUTINE METHODS	344	=head1 COROUTINE OBJECT METHODS
340		345
341	These are the methods you can call on coroutine objects.	346	These are the methods you can call on coroutine objects (or to create
		347	them).
342		348
343	=over 4	349	=over 4
344		350
345	=item new Coro \&sub [, @args...]	351	=item new Coro \&sub [, @args...]
346		352
347	Create a new coroutine and return it. When the sub returns the coroutine	353	Create a new coroutine and return it. When the sub returns, the coroutine
348	automatically terminates as if C<terminate> with the returned values were	354	automatically terminates as if C<terminate> with the returned values were
349	called. To make the coroutine run you must first put it into the ready queue	355	called. To make the coroutine run you must first put it into the ready
350	by calling the ready method.	356	queue by calling the ready method.
351		357
352	See C<async> and C<Coro::State::new> for additional info about the	358	See C<async> and C<Coro::State::new> for additional info about the
353	coroutine environment.	359	coroutine environment.
354		360
355	=cut	361	=cut
356		362
357	sub _run_coro {	363	sub _coro_run {
358	terminate &{+shift};	364	terminate &{+shift};
359	}	365	}
360		366
361	sub new {
362	my $class = shift;
363
364	$class->SUPER::new (\&_run_coro, @_)
365	}
366
367	=item $success = $coroutine->ready	367	=item $success = $coroutine->ready
368		368
369	Put the given coroutine into the ready queue (according to it's priority)	369	Put the given coroutine into the end of its ready queue (there is one
370	and return true. If the coroutine is already in the ready queue, do nothing	370	queue for each priority) and return true. If the coroutine is already in
371	and return false.	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.
372		376
373	=item $is_ready = $coroutine->is_ready	377	=item $is_ready = $coroutine->is_ready
374		378
375	Return wether the coroutine is currently the ready queue or not,	379	Return whether the coroutine is currently the ready queue or not,
376		380
377	=item $coroutine->cancel (arg...)	381	=item $coroutine->cancel (arg...)
378		382
379	Terminates the given coroutine and makes it return the given arguments as	383	Terminates the given coroutine and makes it return the given arguments as
380	status (default: the empty list). Never returns if the coroutine is the	384	status (default: the empty list). Never returns if the coroutine is the
…		…
382		386
383	=cut	387	=cut
384		388
385	sub cancel {	389	sub cancel {
386	my $self = shift;	390	my $self = shift;
387	$self->{_status} = [@_];
388		391
389	if ($current == $self) {	392	if ($current == $self) {
390	push @destroy, $self;	393	terminate @_;
391	$manager->ready;
392	&schedule while 1;
393	} else {	394	} else {
		395	$self->{_status} = [@_];
394	$self->_cancel;	396	$self->_cancel;
395	}	397	}
396	}	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).
397		441
398	=item $coroutine->join	442	=item $coroutine->join
399		443
400	Wait until the coroutine terminates and return any values given to the	444	Wait until the coroutine terminates and return any values given to the
401	C<terminate> or C<cancel> functions. C<join> can be called concurrently	445	C<terminate> or C<cancel> functions. C<join> can be called concurrently
402	from multiple coroutines.	446	from multiple coroutines, and all will be resumed and given the status
		447	return once the C<$coroutine> terminates.
403		448
404	=cut	449	=cut
405		450
406	sub join {	451	sub join {
407	my $self = shift;	452	my $self = shift;
…		…
422		467
423	=item $coroutine->on_destroy (\&cb)	468	=item $coroutine->on_destroy (\&cb)
424		469
425	Registers a callback that is called when this coroutine gets destroyed,	470	Registers a callback that is called when this coroutine gets destroyed,
426	but before it is joined. The callback gets passed the terminate arguments,	471	but before it is joined. The callback gets passed the terminate arguments,
427	if any.	472	if any, and I<must not> die, under any circumstances.
428		473
429	=cut	474	=cut
430		475
431	sub on_destroy {	476	sub on_destroy {
432	my ($self, $cb) = @_;	477	my ($self, $cb) = @_;
…		…
462	higher values mean lower priority, just as in unix).	507	higher values mean lower priority, just as in unix).
463		508
464	=item $olddesc = $coroutine->desc ($newdesc)	509	=item $olddesc = $coroutine->desc ($newdesc)
465		510
466	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
467	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.
468		514
469	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	515	This method simply sets the C<< $coroutine->{desc} >> member to the given
470	can modify this member directly if you wish.	516	string. You can modify this member directly if you wish.
471		517
472	=cut	518	=cut
473		519
474	sub desc {	520	sub desc {
475	my $old = $_[0]{desc};	521	my $old = $_[0]{desc};
476	$_[0]{desc} = $_[1] if @_ > 1;	522	$_[0]{desc} = $_[1] if @_ > 1;
477	$old;	523	$old;
478	}	524	}
479		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
480	=back	531	=back
481		532
482	=head2 GLOBAL FUNCTIONS	533	=head1 GLOBAL FUNCTIONS
483		534
484	=over 4	535	=over 4
485		536
486	=item Coro::nready	537	=item Coro::nready
487		538
488	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,
489	i.e. that can be switched 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
490	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>
491	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
492	that wakes up some coroutines.	544	coroutines.
493		545
494	=item my $guard = Coro::guard { ... }	546	=item my $guard = Coro::guard { ... }
495		547
496	This creates and returns a guard object. Nothing happens until the object	548	This function still exists, but is deprecated. Please use the
497	gets destroyed, in which case the codeblock given as argument will be	549	C<Guard::guard> function instead.
498	executed. This is useful to free locks or other resources in case of a
499	runtime error or when the coroutine gets canceled, as in both cases the
500	guard block will be executed. The guard object supports only one method,
501	C<< ->cancel >>, which will keep the codeblock from being executed.
502		550
503	Example: set some flag and clear it again when the coroutine gets canceled
504	or the function returns:
505
506	sub do_something {
507	my $guard = Coro::guard { $busy = 0 };
508	$busy = 1;
509
510	# do something that requires $busy to be true
511	}
512
513	=cut	551	=cut
514		552
515	sub guard(&) {	553	BEGIN { *guard = \&Guard::guard }
516	bless \(my $cb = $_[0]), "Coro::guard"
517	}
518
519	sub Coro::guard::cancel {
520	${$_[0]} = sub { };
521	}
522
523	sub Coro::guard::DESTROY {
524	${$_[0]}->();
525	}
526
527		554
528	=item unblock_sub { ... }	555	=item unblock_sub { ... }
529		556
530	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,
531	returning the new coderef. This means that the new coderef will return	558	returning a new coderef. Unblocking means that calling the new coderef
532	immediately without blocking, returning nothing, while the original code	559	will return immediately without blocking, returning nothing, while the
533	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.
534		562
535	The reason this function exists is that many event libraries (such as the	563	The reason this function exists is that many event libraries (such as the
536	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
537	of thread-safety). This means you must not block within event callbacks,	565	of reentrancy). This means you must not block within event callbacks,
538	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>.
539		568
540	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
541	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
542	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
543	disk.	572	disk, for example.
544		573
545	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
546	creating event callbacks that want to block.	575	creating event callbacks that want to block.
		576
		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>.
		580
		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>.
547		586
548	=cut	587	=cut
549		588
550	our @unblock_queue;	589	our @unblock_queue;
551		590
…		…
554	# return immediately and can be reused) and because we cannot cede	593	# return immediately and can be reused) and because we cannot cede
555	# inside an event callback.	594	# inside an event callback.
556	our $unblock_scheduler = new Coro sub {	595	our $unblock_scheduler = new Coro sub {
557	while () {	596	while () {
558	while (my $cb = pop @unblock_queue) {	597	while (my $cb = pop @unblock_queue) {
559	# this is an inlined copy of async_pool	598	&async_pool (@$cb);
560	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
561		599
562	$coro->{_invoke} = $cb;
563	$coro->ready;
564	cede; # for short-lived callbacks, this reduces pressure on the coro pool	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
		603	cede;
565	}	604	}
566	schedule; # sleep well	605	schedule; # sleep well
567	}	606	}
568	};	607	};
569	$unblock_scheduler->desc ("[unblock_sub scheduler]");	608	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
570		609
571	sub unblock_sub(&) {	610	sub unblock_sub(&) {
572	my $cb = shift;	611	my $cb = shift;
573		612
574	sub {	613	sub {
575	unshift @unblock_queue, [$cb, @_];	614	unshift @unblock_queue, [$cb, @_];
576	$unblock_scheduler->ready;	615	$unblock_scheduler->ready;
577	}	616	}
578	}	617	}
579		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
580	=back	638	=back
581		639
582	=cut	640	=cut
583		641
584	1;	642	1;
585		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
586	=head1 BUGS/LIMITATIONS	710	=head1 BUGS/LIMITATIONS
587		711
588	- you must make very sure that no coro is still active on global	712	=over 4
589	destruction. very bad things might happen otherwise (usually segfaults).
590		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
591	- 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
592	from the same thread (this requirement might be loosened in the future	724	module from the first thread (this requirement might be removed in the
593	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
594	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
595		742
596	=head1 SEE ALSO	743	=head1 SEE ALSO
597		744
		745	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		746
		747	Debugging: L<Coro::Debug>.
		748
598	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	749	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
599		750
600	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>.
601		753
602	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>.
603		755
604	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>.
605		763
606	=head1 AUTHOR	764	=head1 AUTHOR
607		765
608	Marc Lehmann <schmorp@schmorp.de>	766	Marc Lehmann <schmorp@schmorp.de>
609	http://home.schmorp.de/	767	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.145 by root, Wed Oct 3 16:03:17 2007 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 1.145 by root, Wed Oct 3 16:03:17 2007 UTC vs.
Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC