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

Comparing Coro/Coro.pm (file contents):
Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs.
Revision 1.237 by root, Sat Nov 22 16:37:11 2008 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - real threads in perl
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coroutine
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	For a tutorial-style introduction, please read the L<Coro::Intro>
24	to threads but don't run in parallel at the same time even on SMP	32	manpage. This manpage mainly contains reference information.
25	machines. The specific flavor of coroutine used in this module also
26	guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.
30		33
31	(Perl, however, does not natively support real threads but instead does a	34	This module collection manages coroutines, that is, cooperative
32	very slow and memory-intensive emulation of processes using threads. This	35	threads. Coroutines are similar to kernel threads but don't (in general)
33	is a performance win on Windows machines, and a loss everywhere else).	36	run in parallel at the same time even on SMP machines. The specific flavor
		37	of coroutine used in this module also guarantees you that it will not
		38	switch between coroutines unless necessary, at easily-identified points
		39	in your program, so locking and parallel access are rarely an issue,
		40	making coroutine programming much safer and easier than using other thread
		41	models.
34		42
		43	Unlike the so-called "Perl threads" (which are not actually real threads
		44	but only the windows process emulation ported to unix), Coro provides a
		45	full shared address space, which makes communication between coroutines
		46	very easy. And coroutines are fast, too: disabling the Windows process
		47	emulation code in your perl and using Coro can easily result in a two to
		48	four times speed increase for your programs.
		49
		50	Coro achieves that by supporting multiple running interpreters that share
		51	data, which is especially useful to code pseudo-parallel processes and
		52	for event-based programming, such as multiple HTTP-GET requests running
		53	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		54	into an event-based environment.
		55
35	In this module, coroutines are defined as "callchain + lexical variables +	56	In this module, a coroutines is defined as "callchain + lexical variables
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	57	+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own
37	its own set of lexicals and its own set of perls most important global	58	callchain, its own set of lexicals and its own set of perls most important
38	variables.	59	global variables (see L<Coro::State> for more configuration and background
		60	info).
		61
		62	See also the C<SEE ALSO> section at the end of this document - the Coro
		63	module family is quite large.
39		64
40	=cut	65	=cut
41		66
42	package Coro;	67	package Coro;
43		68
44	use strict;	69	use strict qw(vars subs);
45	no warnings "uninitialized";	70	no warnings "uninitialized";
46		71
47	use Coro::State;	72	use Coro::State;
48		73
49	use base qw(Coro::State Exporter);	74	use base qw(Coro::State Exporter);
50		75
51	our $idle; # idle handler	76	our $idle; # idle handler
52	our $main; # main coroutine	77	our $main; # main coroutine
53	our $current; # current coroutine	78	our $current; # current coroutine
54		79
55	our $VERSION = '4.01';	80	our $VERSION = "5.0";
56		81
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	82	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	83	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	84	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	85	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	86	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		87
63	{	88	=head1 GLOBAL VARIABLES
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96		89
97	=over 4	90	=over 4
98		91
99	=item $main	92	=item $Coro::main
100		93
101	This coroutine represents the main program.	94	This variable stores the coroutine object that represents the main
		95	program. While you cna C<ready> it and do most other things you can do to
		96	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		97	whether you are running in the main program or not.
102		98
103	=cut	99	=cut
104		100
105	$main = new Coro;	101	# $main is now being initialised by Coro::State
106		102
107	=item $current (or as function: current)	103	=item $Coro::current
108		104
109	The current coroutine (the last coroutine switched to). The initial value	105	The coroutine object representing the current coroutine (the last
		106	coroutine that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	107	C<$Coro::main> (of course).
111		108
112	This variable is B<strictly> I<read-only>. It is provided for performance	109	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essential you are encouraged to use the	110	value stored in it and use it as any other coroutine object, but you must
114	C<Coro::current> function instead.	111	not otherwise modify the variable itself.
115		112
116	=cut	113	=cut
117		114
118	$main->{desc} = "[main::]";
119
120	# maybe some other module used Coro::Specific before...
121	$main->{_specific} = $current->{_specific}
122	if $current;
123
124	_set_current $main;
125
126	sub current() { $current }	115	sub current() { $current } # [DEPRECATED]
127		116
128	=item $idle	117	=item $Coro::idle
129		118
130	A callback that is called whenever the scheduler finds no ready coroutines	119	This variable is mainly useful to integrate Coro into event loops. It is
131	to run. The default implementation prints "FATAL: deadlock detected" and	120	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
132	exits, because the program has no other way to continue.	121	pretty low-level functionality.
		122
		123	This variable stores a callback that is called whenever the scheduler
		124	finds no ready coroutines to run. The default implementation prints
		125	"FATAL: deadlock detected" and exits, because the program has no other way
		126	to continue.
133		127
134	This hook is overwritten by modules such as C<Coro::Timer> and	128	This hook is overwritten by modules such as C<Coro::Timer> and
135	C<Coro::Event> to wait on an external event that hopefully wake up a	129	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
136	coroutine so the scheduler can run it.	130	coroutine so the scheduler can run it.
137		131
		132	Note that the callback I<must not>, under any circumstances, block
		133	the current coroutine. Normally, this is achieved by having an "idle
		134	coroutine" that calls the event loop and then blocks again, and then
		135	readying that coroutine in the idle handler.
		136
		137	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		138	technique.
		139
138	Please note that if your callback recursively invokes perl (e.g. for event	140	Please note that if your callback recursively invokes perl (e.g. for event
139	handlers), then it must be prepared to be called recursively.	141	handlers), then it must be prepared to be called recursively itself.
140		142
141	=cut	143	=cut
142		144
143	$idle = sub {	145	$idle = sub {
144	require Carp;	146	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	147	Carp::croak ("FATAL: deadlock detected");
146	};	148	};
147		149
148	sub _cancel {
149	my ($self) = @_;
150
151	# free coroutine data and mark as destructed
152	$self->_destroy
153	or return;
154
155	# call all destruction callbacks
156	$_->(@{$self->{_status}})
157	for @{(delete $self->{_on_destroy}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	150	# this coroutine is necessary because a coroutine
161	# cannot destroy itself.	151	# cannot destroy itself.
162	my @destroy;	152	our @destroy;
163	my $manager;	153	our $manager;
164		154
165	$manager = new Coro sub {	155	$manager = new Coro sub {
166	while () {	156	while () {
167	(shift @destroy)->_cancel	157	Coro::_cancel shift @destroy
168	while @destroy;	158	while @destroy;
169		159
170	&schedule;	160	&schedule;
171	}	161	}
172	};	162	};
173	$manager->desc ("[coro manager]");	163	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	164	$manager->prio (PRIO_MAX);
175		165
176	# static methods. not really.
177
178	=back	166	=back
179		167
180	=head2 STATIC METHODS	168	=head1 SIMPLE COROUTINE CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		169
184	=over 4	170	=over 4
185		171
186	=item async { ... } [@args...]	172	=item async { ... } [@args...]
187		173
188	Create a new asynchronous coroutine and return it's coroutine object	174	Create a new coroutine and return it's coroutine object (usually
189	(usually unused). When the sub returns the new coroutine is automatically	175	unused). The coroutine will be put into the ready queue, so
		176	it will start running automatically on the next scheduler run.
		177
		178	The first argument is a codeblock/closure that should be executed in the
		179	coroutine. When it returns argument returns the coroutine is automatically
190	terminated.	180	terminated.
191		181
		182	The remaining arguments are passed as arguments to the closure.
		183
192	See the C<Coro::State::new> constructor for info about the coroutine	184	See the C<Coro::State::new> constructor for info about the coroutine
193	environment.	185	environment in which coroutines are executed.
194		186
195	Calling C<exit> in a coroutine will do the same as calling exit outside	187	Calling C<exit> in a coroutine will do the same as calling exit outside
196	the coroutine. Likewise, when the coroutine dies, the program will exit,	188	the coroutine. Likewise, when the coroutine dies, the program will exit,
197	just as it would in the main program.	189	just as it would in the main program.
198		190
		191	If you do not want that, you can provide a default C<die> handler, or
		192	simply avoid dieing (by use of C<eval>).
		193
199	# create a new coroutine that just prints its arguments	194	Example: Create a new coroutine that just prints its arguments.
		195
200	async {	196	async {
201	print "@_\n";	197	print "@_\n";
202	} 1,2,3,4;	198	} 1,2,3,4;
203		199
204	=cut	200	=cut
210	}	206	}
211		207
212	=item async_pool { ... } [@args...]	208	=item async_pool { ... } [@args...]
213		209
214	Similar to C<async>, but uses a coroutine pool, so you should not call	210	Similar to C<async>, but uses a coroutine pool, so you should not call
215	terminate or join (although you are allowed to), and you get a coroutine	211	terminate or join on it (although you are allowed to), and you get a
216	that might have executed other code already (which can be good or bad :).	212	coroutine that might have executed other code already (which can be good
		213	or bad :).
217		214
		215	On the plus side, this function is about twice as fast as creating (and
		216	destroying) a completely new coroutine, so if you need a lot of generic
		217	coroutines in quick successsion, use C<async_pool>, not C<async>.
		218
218	Also, the block is executed in an C<eval> context and a warning will be	219	The code block is executed in an C<eval> context and a warning will be
219	issued in case of an exception instead of terminating the program, as	220	issued in case of an exception instead of terminating the program, as
220	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	221	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
221	will not work in the expected way, unless you call terminate or cancel,	222	will not work in the expected way, unless you call terminate or cancel,
222	which somehow defeats the purpose of pooling.	223	which somehow defeats the purpose of pooling (but is fine in the
		224	exceptional case).
223		225
224	The priority will be reset to C<0> after each job, tracing will be	226	The priority will be reset to C<0> after each run, tracing will be
225	disabled, the description will be reset and the default output filehandle	227	disabled, the description will be reset and the default output filehandle
226	gets restored, so you can change alkl these. Otherwise the coroutine will	228	gets restored, so you can change all these. Otherwise the coroutine will
227	be re-used "as-is": most notably if you change other per-coroutine global	229	be re-used "as-is": most notably if you change other per-coroutine global
228	stuff such as C<$/> you need to revert that change, which is most simply	230	stuff such as C<$/> you I<must needs> revert that change, which is most
229	done by using local as in C< local $/ >.	231	simply done by using local as in: C<< local $/ >>.
230		232
231	The pool size is limited to 8 idle coroutines (this can be adjusted by	233	The idle pool size is limited to C<8> idle coroutines (this can be
232	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	234	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
233	required.	235	coros as required.
234		236
235	If you are concerned about pooled coroutines growing a lot because a	237	If you are concerned about pooled coroutines growing a lot because a
236	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	238	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
237	{ terminate }> once per second or so to slowly replenish the pool. In	239	{ terminate }> once per second or so to slowly replenish the pool. In
238	addition to that, when the stacks used by a handler grows larger than 16kb	240	addition to that, when the stacks used by a handler grows larger than 32kb
239	(adjustable with $Coro::POOL_RSS) it will also exit.	241	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
240		242
241	=cut	243	=cut
242		244
243	our $POOL_SIZE = 8;	245	our $POOL_SIZE = 8;
244	our $POOL_RSS = 16 * 1024;	246	our $POOL_RSS = 32 * 1024;
245	our @async_pool;	247	our @async_pool;
246		248
247	sub pool_handler {	249	sub pool_handler {
248	my $cb;
249
250	while () {	250	while () {
251	eval {	251	eval {
252	while () {	252	&{&_pool_handler} while 1;
253	_pool_1 $cb;
254	&$cb;
255	_pool_2 $cb;
256	&schedule;
257	}
258	};	253	};
259		254
260	last if $@ eq "\3terminate\2\n";
261	warn $@ if $@;	255	warn $@ if $@;
262	}	256	}
263	}	257	}
264		258
265	sub async_pool(&@) {	259	=back
266	# this is also inlined into the unlock_scheduler
267	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
268		260
269	$coro->{_invoke} = [@_];	261	=head1 STATIC METHODS
270	$coro->ready;
271		262
272	$coro	263	Static methods are actually functions that implicitly operate on the
273	}	264	current coroutine.
		265
		266	=over 4
274		267
275	=item schedule	268	=item schedule
276		269
277	Calls the scheduler. Please note that the current coroutine will not be put	270	Calls the scheduler. The scheduler will find the next coroutine that is
		271	to be run from the ready queue and switches to it. The next coroutine
		272	to be run is simply the one with the highest priority that is longest
		273	in its ready queue. If there is no coroutine ready, it will clal the
		274	C<$Coro::idle> hook.
		275
		276	Please note that the current coroutine will I<not> be put into the ready
278	into the ready queue, so calling this function usually means you will	277	queue, so calling this function usually means you will never be called
279	never be called again unless something else (e.g. an event handler) calls	278	again unless something else (e.g. an event handler) calls C<< ->ready >>,
280	ready.	279	thus waking you up.
281		280
282	The canonical way to wait on external events is this:	281	This makes C<schedule> I<the> generic method to use to block the current
		282	coroutine and wait for events: first you remember the current coroutine in
		283	a variable, then arrange for some callback of yours to call C<< ->ready
		284	>> on that once some event happens, and last you call C<schedule> to put
		285	yourself to sleep. Note that a lot of things can wake your coroutine up,
		286	so you need to check whether the event indeed happened, e.g. by storing the
		287	status in a variable.
283		288
284	{	289	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
285	# remember current coroutine
286	my $current = $Coro::current;
287
288	# register a hypothetical event handler
289	on_event_invoke sub {
290	# wake up sleeping coroutine
291	$current->ready;
292	undef $current;
293	};
294
295	# call schedule until event occurred.
296	# in case we are woken up for other reasons
297	# (current still defined), loop.
298	Coro::schedule while $current;
299	}
300		290
301	=item cede	291	=item cede
302		292
303	"Cede" to other coroutines. This function puts the current coroutine into the	293	"Cede" to other coroutines. This function puts the current coroutine into
304	ready queue and calls C<schedule>, which has the effect of giving up the	294	the ready queue and calls C<schedule>, which has the effect of giving
305	current "timeslice" to other coroutines of the same or higher priority.	295	up the current "timeslice" to other coroutines of the same or higher
		296	priority. Once your coroutine gets its turn again it will automatically be
		297	resumed.
306		298
307	Returns true if at least one coroutine switch has happened.	299	This function is often called C<yield> in other languages.
308		300
309	=item Coro::cede_notself	301	=item Coro::cede_notself
310		302
311	Works like cede, but is not exported by default and will cede to any	303	Works like cede, but is not exported by default and will cede to I<any>
312	coroutine, regardless of priority, once.	304	coroutine, regardless of priority. This is useful sometimes to ensure
313		305	progress is made.
314	Returns true if at least one coroutine switch has happened.
315		306
316	=item terminate [arg...]	307	=item terminate [arg...]
317		308
318	Terminates the current coroutine with the given status values (see L<cancel>).	309	Terminates the current coroutine with the given status values (see L<cancel>).
319		310
…		…
321		312
322	Kills/terminates/cancels all coroutines except the currently running	313	Kills/terminates/cancels all coroutines except the currently running
323	one. This is useful after a fork, either in the child or the parent, as	314	one. This is useful after a fork, either in the child or the parent, as
324	usually only one of them should inherit the running coroutines.	315	usually only one of them should inherit the running coroutines.
325		316
326	=cut	317	Note that while this will try to free some of the main programs resources,
		318	you cannot free all of them, so if a coroutine that is not the main
		319	program calls this function, there will be some one-time resource leak.
327		320
328	sub terminate {	321	=cut
329	$current->cancel (@_);
330	}
331		322
332	sub killall {	323	sub killall {
333	for (Coro::State::list) {	324	for (Coro::State::list) {
334	$_->cancel	325	$_->cancel
335	if $_ != $current && UNIVERSAL::isa $_, "Coro";	326	if $_ != $current && UNIVERSAL::isa $_, "Coro";
336	}	327	}
337	}	328	}
338		329
339	=back	330	=back
340		331
341	# dynamic methods
342
343	=head2 COROUTINE METHODS	332	=head1 COROUTINE OBJECT METHODS
344		333
345	These are the methods you can call on coroutine objects.	334	These are the methods you can call on coroutine objects (or to create
		335	them).
346		336
347	=over 4	337	=over 4
348		338
349	=item new Coro \&sub [, @args...]	339	=item new Coro \&sub [, @args...]
350		340
351	Create a new coroutine and return it. When the sub returns the coroutine	341	Create a new coroutine and return it. When the sub returns, the coroutine
352	automatically terminates as if C<terminate> with the returned values were	342	automatically terminates as if C<terminate> with the returned values were
353	called. To make the coroutine run you must first put it into the ready queue	343	called. To make the coroutine run you must first put it into the ready
354	by calling the ready method.	344	queue by calling the ready method.
355		345
356	See C<async> and C<Coro::State::new> for additional info about the	346	See C<async> and C<Coro::State::new> for additional info about the
357	coroutine environment.	347	coroutine environment.
358		348
359	=cut	349	=cut
360		350
361	sub _run_coro {	351	sub _terminate {
362	terminate &{+shift};	352	terminate &{+shift};
363	}	353	}
364		354
365	sub new {
366	my $class = shift;
367
368	$class->SUPER::new (\&_run_coro, @_)
369	}
370
371	=item $success = $coroutine->ready	355	=item $success = $coroutine->ready
372		356
373	Put the given coroutine into the ready queue (according to it's priority)	357	Put the given coroutine into the end of its ready queue (there is one
374	and return true. If the coroutine is already in the ready queue, do nothing	358	queue for each priority) and return true. If the coroutine is already in
375	and return false.	359	the ready queue, do nothing and return false.
		360
		361	This ensures that the scheduler will resume this coroutine automatically
		362	once all the coroutines of higher priority and all coroutines of the same
		363	priority that were put into the ready queue earlier have been resumed.
376		364
377	=item $is_ready = $coroutine->is_ready	365	=item $is_ready = $coroutine->is_ready
378		366
379	Return wether the coroutine is currently the ready queue or not,	367	Return whether the coroutine is currently the ready queue or not,
380		368
381	=item $coroutine->cancel (arg...)	369	=item $coroutine->cancel (arg...)
382		370
383	Terminates the given coroutine and makes it return the given arguments as	371	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	372	status (default: the empty list). Never returns if the coroutine is the
…		…
386		374
387	=cut	375	=cut
388		376
389	sub cancel {	377	sub cancel {
390	my $self = shift;	378	my $self = shift;
391	$self->{_status} = [@_];
392		379
393	if ($current == $self) {	380	if ($current == $self) {
394	push @destroy, $self;	381	terminate @_;
395	$manager->ready;
396	&schedule while 1;
397	} else {	382	} else {
		383	$self->{_status} = [@_];
398	$self->_cancel;	384	$self->_cancel;
399	}	385	}
400	}	386	}
		387
		388	=item $coroutine->schedule_to
		389
		390	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		391	of continuing with the next coro from the ready queue, always switch to
		392	the given coroutine object (regardless of priority etc.). The readyness
		393	state of that coroutine isn't changed.
		394
		395	This is an advanced method for special cases - I'd love to hear about any
		396	uses for this one.
		397
		398	=item $coroutine->cede_to
		399
		400	Like C<schedule_to>, but puts the current coroutine into the ready
		401	queue. This has the effect of temporarily switching to the given
		402	coroutine, and continuing some time later.
		403
		404	This is an advanced method for special cases - I'd love to hear about any
		405	uses for this one.
		406
		407	=item $coroutine->throw ([$scalar])
		408
		409	If C<$throw> is specified and defined, it will be thrown as an exception
		410	inside the coroutine at the next convenient point in time. Otherwise
		411	clears the exception object.
		412
		413	Coro will check for the exception each time a schedule-like-function
		414	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		415	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		416	detect this case and return early in case an exception is pending.
		417
		418	The exception object will be thrown "as is" with the specified scalar in
		419	C<$@>, i.e. if it is a string, no line number or newline will be appended
		420	(unlike with C<die>).
		421
		422	This can be used as a softer means than C<cancel> to ask a coroutine to
		423	end itself, although there is no guarantee that the exception will lead to
		424	termination, and if the exception isn't caught it might well end the whole
		425	program.
		426
		427	You might also think of C<throw> as being the moral equivalent of
		428	C<kill>ing a coroutine with a signal (in this case, a scalar).
401		429
402	=item $coroutine->join	430	=item $coroutine->join
403		431
404	Wait until the coroutine terminates and return any values given to the	432	Wait until the coroutine terminates and return any values given to the
405	C<terminate> or C<cancel> functions. C<join> can be called concurrently	433	C<terminate> or C<cancel> functions. C<join> can be called concurrently
406	from multiple coroutines.	434	from multiple coroutines, and all will be resumed and given the status
		435	return once the C<$coroutine> terminates.
407		436
408	=cut	437	=cut
409		438
410	sub join {	439	sub join {
411	my $self = shift;	440	my $self = shift;
…		…
426		455
427	=item $coroutine->on_destroy (\&cb)	456	=item $coroutine->on_destroy (\&cb)
428		457
429	Registers a callback that is called when this coroutine gets destroyed,	458	Registers a callback that is called when this coroutine gets destroyed,
430	but before it is joined. The callback gets passed the terminate arguments,	459	but before it is joined. The callback gets passed the terminate arguments,
431	if any.	460	if any, and I<must not> die, under any circumstances.
432		461
433	=cut	462	=cut
434		463
435	sub on_destroy {	464	sub on_destroy {
436	my ($self, $cb) = @_;	465	my ($self, $cb) = @_;
…		…
466	higher values mean lower priority, just as in unix).	495	higher values mean lower priority, just as in unix).
467		496
468	=item $olddesc = $coroutine->desc ($newdesc)	497	=item $olddesc = $coroutine->desc ($newdesc)
469		498
470	Sets (or gets in case the argument is missing) the description for this	499	Sets (or gets in case the argument is missing) the description for this
471	coroutine. This is just a free-form string you can associate with a coroutine.	500	coroutine. This is just a free-form string you can associate with a
		501	coroutine.
472		502
473	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	503	This method simply sets the C<< $coroutine->{desc} >> member to the given
474	can modify this member directly if you wish.	504	string. You can modify this member directly if you wish.
475		505
476	=cut	506	=cut
477		507
478	sub desc {	508	sub desc {
479	my $old = $_[0]{desc};	509	my $old = $_[0]{desc};
480	$_[0]{desc} = $_[1] if @_ > 1;	510	$_[0]{desc} = $_[1] if @_ > 1;
481	$old;	511	$old;
482	}	512	}
483		513
		514	sub transfer {
		515	require Carp;
		516	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		517	}
		518
484	=back	519	=back
485		520
486	=head2 GLOBAL FUNCTIONS	521	=head1 GLOBAL FUNCTIONS
487		522
488	=over 4	523	=over 4
489		524
490	=item Coro::nready	525	=item Coro::nready
491		526
492	Returns the number of coroutines that are currently in the ready state,	527	Returns the number of coroutines that are currently in the ready state,
493	i.e. that can be switched to. The value C<0> means that the only runnable	528	i.e. that can be switched to by calling C<schedule> directory or
		529	indirectly. The value C<0> means that the only runnable coroutine is the
494	coroutine is the currently running one, so C<cede> would have no effect,	530	currently running one, so C<cede> would have no effect, and C<schedule>
495	and C<schedule> would cause a deadlock unless there is an idle handler	531	would cause a deadlock unless there is an idle handler that wakes up some
496	that wakes up some coroutines.	532	coroutines.
497		533
498	=item my $guard = Coro::guard { ... }	534	=item my $guard = Coro::guard { ... }
499		535
500	This creates and returns a guard object. Nothing happens until the object	536	This creates and returns a guard object. Nothing happens until the object
501	gets destroyed, in which case the codeblock given as argument will be	537	gets destroyed, in which case the codeblock given as argument will be
…		…
530		566
531		567
532	=item unblock_sub { ... }	568	=item unblock_sub { ... }
533		569
534	This utility function takes a BLOCK or code reference and "unblocks" it,	570	This utility function takes a BLOCK or code reference and "unblocks" it,
535	returning the new coderef. This means that the new coderef will return	571	returning a new coderef. Unblocking means that calling the new coderef
536	immediately without blocking, returning nothing, while the original code	572	will return immediately without blocking, returning nothing, while the
537	ref will be called (with parameters) from within its own coroutine.	573	original code ref will be called (with parameters) from within another
		574	coroutine.
538		575
539	The reason this function exists is that many event libraries (such as the	576	The reason this function exists is that many event libraries (such as the
540	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	577	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
541	of thread-safety). This means you must not block within event callbacks,	578	of thread-safety). This means you must not block within event callbacks,
542	otherwise you might suffer from crashes or worse.	579	otherwise you might suffer from crashes or worse. The only event library
		580	currently known that is safe to use without C<unblock_sub> is L<EV>.
543		581
544	This function allows your callbacks to block by executing them in another	582	This function allows your callbacks to block by executing them in another
545	coroutine where it is safe to block. One example where blocking is handy	583	coroutine where it is safe to block. One example where blocking is handy
546	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	584	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
547	disk.	585	disk, for example.
548		586
549	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	587	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
550	creating event callbacks that want to block.	588	creating event callbacks that want to block.
		589
		590	If your handler does not plan to block (e.g. simply sends a message to
		591	another coroutine, or puts some other coroutine into the ready queue),
		592	there is no reason to use C<unblock_sub>.
		593
		594	Note that you also need to use C<unblock_sub> for any other callbacks that
		595	are indirectly executed by any C-based event loop. For example, when you
		596	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		597	provides callbacks that are the result of some event callback, then you
		598	must not block either, or use C<unblock_sub>.
551		599
552	=cut	600	=cut
553		601
554	our @unblock_queue;	602	our @unblock_queue;
555		603
…		…
558	# return immediately and can be reused) and because we cannot cede	606	# return immediately and can be reused) and because we cannot cede
559	# inside an event callback.	607	# inside an event callback.
560	our $unblock_scheduler = new Coro sub {	608	our $unblock_scheduler = new Coro sub {
561	while () {	609	while () {
562	while (my $cb = pop @unblock_queue) {	610	while (my $cb = pop @unblock_queue) {
563	# this is an inlined copy of async_pool	611	&async_pool (@$cb);
564	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
565		612
566	$coro->{_invoke} = $cb;
567	$coro->ready;
568	cede; # for short-lived callbacks, this reduces pressure on the coro pool	613	# for short-lived callbacks, this reduces pressure on the coro pool
		614	# as the chance is very high that the async_poll coro will be back
		615	# in the idle state when cede returns
		616	cede;
569	}	617	}
570	schedule; # sleep well	618	schedule; # sleep well
571	}	619	}
572	};	620	};
573	$unblock_scheduler->desc ("[unblock_sub scheduler]");	621	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
574		622
575	sub unblock_sub(&) {	623	sub unblock_sub(&) {
576	my $cb = shift;	624	my $cb = shift;
577		625
578	sub {	626	sub {
579	unshift @unblock_queue, [$cb, @_];	627	unshift @unblock_queue, [$cb, @_];
580	$unblock_scheduler->ready;	628	$unblock_scheduler->ready;
581	}	629	}
582	}	630	}
583		631
		632	=item $cb = Coro::rouse_cb
		633
		634	Create and return a "rouse callback". That's a code reference that, when
		635	called, will save its arguments and notify the owner coroutine of the
		636	callback.
		637
		638	See the next function.
		639
		640	=item @args = Coro::rouse_wait [$cb]
		641
		642	Wait for the specified rouse callback (or the last one tht was created in
		643	this coroutine).
		644
		645	As soon as the callback is invoked (or when the calback was invoked before
		646	C<rouse_wait>), it will return a copy of the arguments originally passed
		647	to the rouse callback.
		648
		649	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		650
584	=back	651	=back
585		652
586	=cut	653	=cut
587		654
588	1;	655	1;
589		656
		657	=head1 HOW TO WAIT FOR A CALLBACK
		658
		659	It is very common for a coroutine to wait for some callback to be
		660	called. This occurs naturally when you use coroutines in an otherwise
		661	event-based program, or when you use event-based libraries.
		662
		663	These typically register a callback for some event, and call that callback
		664	when the event occured. In a coroutine, however, you typically want to
		665	just wait for the event, simplyifying things.
		666
		667	For example C<< AnyEvent->child >> registers a callback to be called when
		668	a specific child has exited:
		669
		670	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		671
		672	But from withina coroutine, you often just want to write this:
		673
		674	my $status = wait_for_child $pid;
		675
		676	Coro offers two functions specifically designed to make this easy,
		677	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		678
		679	The first function, C<rouse_cb>, generates and returns a callback that,
		680	when invoked, will save it's arguments and notify the coroutine that
		681	created the callback.
		682
		683	The second function, C<rouse_wait>, waits for the callback to be called
		684	(by calling C<schedule> to go to sleep) and returns the arguments
		685	originally passed to the callback.
		686
		687	Using these functions, it becomes easy to write the C<wait_for_child>
		688	function mentioned above:
		689
		690	sub wait_for_child($) {
		691	my ($pid) = @_;
		692
		693	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		694
		695	my ($rpid, $rstatus) = Coro::rouse_wait;
		696	$rstatus
		697	}
		698
		699	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		700	you can roll your own, using C<schedule>:
		701
		702	sub wait_for_child($) {
		703	my ($pid) = @_;
		704
		705	# store the current coroutine in $current,
		706	# and provide result variables for the closure passed to ->child
		707	my $current = $Coro::current;
		708	my ($done, $rstatus);
		709
		710	# pass a closure to ->child
		711	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		712	$rstatus = $_[1]; # remember rstatus
		713	$done = 1; # mark $rstatus as valud
		714	});
		715
		716	# wait until the closure has been called
		717	schedule while !$done;
		718
		719	$rstatus
		720	}
		721
		722
590	=head1 BUGS/LIMITATIONS	723	=head1 BUGS/LIMITATIONS
591		724
592	- you must make very sure that no coro is still active on global	725	=over 4
593	destruction. very bad things might happen otherwise (usually segfaults).
594		726
		727	=item fork with pthread backend
		728
		729	When Coro is compiled using the pthread backend (which isn't recommended
		730	but required on many BSDs as their libcs are completely broken), then
		731	coroutines will not survive a fork. There is no known workaround except to
		732	fix your libc and use a saner backend.
		733
		734	=item perl process emulation ("threads")
		735
595	- this module is not thread-safe. You should only ever use this module	736	This module is not perl-pseudo-thread-safe. You should only ever use this
596	from the same thread (this requirement might be loosened in the future	737	module from the same thread (this requirement might be removed in the
597	to allow per-thread schedulers, but Coro::State does not yet allow	738	future to allow per-thread schedulers, but Coro::State does not yet allow
598	this).	739	this). I recommend disabling thread support and using processes, as having
		740	the windows process emulation enabled under unix roughly halves perl
		741	performance, even when not used.
		742
		743	=item coroutine switching not signal safe
		744
		745	You must not switch to another coroutine from within a signal handler
		746	(only relevant with %SIG - most event libraries provide safe signals).
		747
		748	That means you I<MUST NOT> call any function that might "block" the
		749	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		750	anything that calls those. Everything else, including calling C<ready>,
		751	works.
		752
		753	=back
		754
599		755
600	=head1 SEE ALSO	756	=head1 SEE ALSO
601		757
		758	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		759
		760	Debugging: L<Coro::Debug>.
		761
602	Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	762	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
603		763
604	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	764	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		765	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
605		766
606	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	767	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
607		768
608	Embedding: L<Coro:MakeMaker>	769	Compatibility: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		770	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		771	L<Coro::Select>.
		772
		773	XS API: L<Coro::MakeMaker>.
		774
		775	Low level Configuration, Coroutine Environment: L<Coro::State>.
609		776
610	=head1 AUTHOR	777	=head1 AUTHOR
611		778
612	Marc Lehmann <schmorp@schmorp.de>	779	Marc Lehmann <schmorp@schmorp.de>
613	http://home.schmorp.de/	780	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs. Revision 1.237 by root, Sat Nov 22 16:37:11 2008 UTC

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Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs.
Revision 1.237 by root, Sat Nov 22 16:37:11 2008 UTC