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

Comparing Coro/Coro.pm (file contents):
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs.
Revision 1.248 by root, Mon Dec 15 15:03:31 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
11	print "2\n";	11	print "2\n";
12	cede; # yield back to main	12	cede; # yield back to main
13	print "4\n";	13	print "4\n";
14	};	14	};
15	print "1\n";	15	print "1\n";
16	cede; # yield to coroutine	16	cede; # yield to coro
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
21	use Coro::Semaphore;	21	use Coro::Semaphore;
…		…
26	$locked = 1;	26	$locked = 1;
27	$lock->up;	27	$lock->up;
28		28
29	=head1 DESCRIPTION	29	=head1 DESCRIPTION
30		30
31	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
32	threads but don't (in general) run in parallel at the same time even	32	manpage. This manpage mainly contains reference information.
33	on SMP machines. The specific flavor of coroutine used in this module
34	also guarantees you that it will not switch between coroutines unless
35	necessary, at easily-identified points in your program, so locking and
36	parallel access are rarely an issue, making coroutine programming much
37	safer and easier than threads programming.
38		33
39	Unlike a normal perl program, however, coroutines allow you to have	34	This module collection manages continuations in general, most often in
40	multiple running interpreters that share data, which is especially useful	35	the form of cooperative threads (also called coros, or simply "coro"
41	to code pseudo-parallel processes and for event-based programming, such as	36	in the documentation). They are similar to kernel threads but don't (in
42	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to	37	general) run in parallel at the same time even on SMP machines. The
43	learn more.	38	specific flavor of thread offered by this module also guarantees you that
		39	it will not switch between threads unless necessary, at easily-identified
		40	points in your program, so locking and parallel access are rarely an
		41	issue, making thread programming much safer and easier than using other
		42	thread models.
44		43
45	Coroutines are also useful because Perl has no support for threads (the so	44	Unlike the so-called "Perl threads" (which are not actually real threads
46	called "threads" that perl offers are nothing more than the (bad) process	45	but only the windows process emulation ported to unix), Coro provides a
47	emulation coming from the Windows platform: On standard operating systems	46	full shared address space, which makes communication between threads
48	they serve no purpose whatsoever, except by making your programs slow and	47	very easy. And threads are fast, too: disabling the Windows process
49	making them use a lot of memory. Best disable them when building perl, or	48	emulation code in your perl and using Coro can easily result in a two to
50	aks your software vendor/distributor to do it for you).	49	four times speed increase for your programs.
51		50
		51	Coro achieves that by supporting multiple running interpreters that share
		52	data, which is especially useful to code pseudo-parallel processes and
		53	for event-based programming, such as multiple HTTP-GET requests running
		54	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		55	into an event-based environment.
		56
52	In this module, coroutines are defined as "callchain + lexical variables +	57	In this module, a thread is defined as "callchain + lexical variables +
53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	58	@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,
54	its own set of lexicals and its own set of perls most important global	59	its own set of lexicals and its own set of perls most important global
55	variables (see L<Coro::State> for more configuration).	60	variables (see L<Coro::State> for more configuration and background info).
		61
		62	See also the C<SEE ALSO> section at the end of this document - the Coro
		63	module family is quite large.
56		64
57	=cut	65	=cut
58		66
59	package Coro;	67	package Coro;
60		68
61	use strict;	69	use strict qw(vars subs);
62	no warnings "uninitialized";	70	no warnings "uninitialized";
63		71
		72	use Guard ();
		73
64	use Coro::State;	74	use Coro::State;
65		75
66	use base qw(Coro::State Exporter);	76	use base qw(Coro::State Exporter);
67		77
68	our $idle; # idle handler	78	our $idle; # idle handler
69	our $main; # main coroutine	79	our $main; # main coro
70	our $current; # current coroutine	80	our $current; # current coro
71		81
72	our $VERSION = 4.8;	82	our $VERSION = 5.13;
73		83
74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	84	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
75	our %EXPORT_TAGS = (	85	our %EXPORT_TAGS = (
76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	86	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
77	);	87	);
78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	88	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
79		89
		90	=head1 GLOBAL VARIABLES
		91
80	=over 4	92	=over 4
81		93
82	=item $Coro::main	94	=item $Coro::main
83		95
84	This variable stores the coroutine object that represents the main	96	This variable stores the Coro object that represents the main
85	program. While you cna C<ready> it and do most other things you can do to	97	program. While you cna C<ready> it and do most other things you can do to
86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	98	coro, it is mainly useful to compare again C<$Coro::current>, to see
87	whether you are running in the main program or not.	99	whether you are running in the main program or not.
88		100
89	=cut	101	=cut
90		102
91	$main = new Coro;	103	# $main is now being initialised by Coro::State
92		104
93	=item $Coro::current	105	=item $Coro::current
94		106
95	The coroutine object representing the current coroutine (the last	107	The Coro object representing the current coro (the last
96	coroutine that the Coro scheduler switched to). The initial value is	108	coro that the Coro scheduler switched to). The initial value is
97	C<$main> (of course).	109	C<$Coro::main> (of course).
98		110
99	This variable is B<strictly> I<read-only>. You can take copies of the	111	This variable is B<strictly> I<read-only>. You can take copies of the
100	value stored in it and use it as any other coroutine object, but you must	112	value stored in it and use it as any other Coro object, but you must
101	not otherwise modify the variable itself.	113	not otherwise modify the variable itself.
102		114
103	=cut	115	=cut
104		116
105	$main->{desc} = "[main::]";
106
107	# maybe some other module used Coro::Specific before...
108	$main->{_specific} = $current->{_specific}
109	if $current;
110
111	_set_current $main;
112
113	sub current() { $current } # [DEPRECATED]	117	sub current() { $current } # [DEPRECATED]
114		118
115	=item $Coro::idle	119	=item $Coro::idle
116		120
117	This variable is mainly useful to integrate Coro into event loops. It is	121	This variable is mainly useful to integrate Coro into event loops. It is
118	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is	122	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
119	pretty low-level functionality.	123	pretty low-level functionality.
120		124
121	This variable stores a callback that is called whenever the scheduler	125	This variable stores either a Coro object or a callback.
		126
		127	If it is a callback, the it is called whenever the scheduler finds no
122	finds no ready coroutines to run. The default implementation prints	128	ready coros to run. The default implementation prints "FATAL:
123	"FATAL: deadlock detected" and exits, because the program has no other way	129	deadlock detected" and exits, because the program has no other way to
124	to continue.	130	continue.
125		131
		132	If it is a coro object, then this object will be readied (without
		133	invoking any ready hooks, however) when the scheduler finds no other ready
		134	coros to run.
		135
126	This hook is overwritten by modules such as C<Coro::Timer> and	136	This hook is overwritten by modules such as C<Coro::EV> and
127	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	137	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
128	coroutine so the scheduler can run it.	138	coro so the scheduler can run it.
129		139
130	Note that the callback I<must not>, under any circumstances, block	140	Note that the callback I<must not>, under any circumstances, block
131	the current coroutine. Normally, this is achieved by having an "idle	141	the current coro. Normally, this is achieved by having an "idle
132	coroutine" that calls the event loop and then blocks again, and then	142	coro" that calls the event loop and then blocks again, and then
133	readying that coroutine in the idle handler.	143	readying that coro in the idle handler, or by simply placing the idle
		144	coro in this variable.
134		145
135	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	146	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
136	technique.	147	technique.
137		148
138	Please note that if your callback recursively invokes perl (e.g. for event	149	Please note that if your callback recursively invokes perl (e.g. for event
…		…
143	$idle = sub {	154	$idle = sub {
144	require Carp;	155	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	156	Carp::croak ("FATAL: deadlock detected");
146	};	157	};
147		158
148	sub _cancel {
149	my ($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	159	# this coro is necessary because a coro
161	# cannot destroy itself.	160	# cannot destroy itself.
162	my @destroy;	161	our @destroy;
163	my $manager;	162	our $manager;
164		163
165	$manager = new Coro sub {	164	$manager = new Coro sub {
166	while () {	165	while () {
167	(shift @destroy)->_cancel	166	Coro::State::cancel shift @destroy
168	while @destroy;	167	while @destroy;
169		168
170	&schedule;	169	&schedule;
171	}	170	}
172	};	171	};
173	$manager->desc ("[coro manager]");	172	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	173	$manager->prio (PRIO_MAX);
175		174
176	=back	175	=back
177		176
178	=head2 SIMPLE COROUTINE CREATION	177	=head1 SIMPLE CORO CREATION
179		178
180	=over 4	179	=over 4
181		180
182	=item async { ... } [@args...]	181	=item async { ... } [@args...]
183		182
184	Create a new coroutine and return it's coroutine object (usually	183	Create a new coro and return its Coro object (usually
185	unused). The coroutine will be put into the ready queue, so	184	unused). The coro will be put into the ready queue, so
186	it will start running automatically on the next scheduler run.	185	it will start running automatically on the next scheduler run.
187		186
188	The first argument is a codeblock/closure that should be executed in the	187	The first argument is a codeblock/closure that should be executed in the
189	coroutine. When it returns argument returns the coroutine is automatically	188	coro. When it returns argument returns the coro is automatically
190	terminated.	189	terminated.
191		190
192	The remaining arguments are passed as arguments to the closure.	191	The remaining arguments are passed as arguments to the closure.
193		192
194	See the C<Coro::State::new> constructor for info about the coroutine	193	See the C<Coro::State::new> constructor for info about the coro
195	environment in which coroutines are executed.	194	environment in which coro are executed.
196		195
197	Calling C<exit> in a coroutine will do the same as calling exit outside	196	Calling C<exit> in a coro will do the same as calling exit outside
198	the coroutine. Likewise, when the coroutine dies, the program will exit,	197	the coro. Likewise, when the coro dies, the program will exit,
199	just as it would in the main program.	198	just as it would in the main program.
200		199
201	If you do not want that, you can provide a default C<die> handler, or	200	If you do not want that, you can provide a default C<die> handler, or
202	simply avoid dieing (by use of C<eval>).	201	simply avoid dieing (by use of C<eval>).
203		202
204	Example: Create a new coroutine that just prints its arguments.	203	Example: Create a new coro that just prints its arguments.
205		204
206	async {	205	async {
207	print "@_\n";	206	print "@_\n";
208	} 1,2,3,4;	207	} 1,2,3,4;
209		208
…		…
215	$coro	214	$coro
216	}	215	}
217		216
218	=item async_pool { ... } [@args...]	217	=item async_pool { ... } [@args...]
219		218
220	Similar to C<async>, but uses a coroutine pool, so you should not call	219	Similar to C<async>, but uses a coro pool, so you should not call
221	terminate or join on it (although you are allowed to), and you get a	220	terminate or join on it (although you are allowed to), and you get a
222	coroutine that might have executed other code already (which can be good	221	coro that might have executed other code already (which can be good
223	or bad :).	222	or bad :).
224		223
225	On the plus side, this function is faster than creating (and destroying)	224	On the plus side, this function is about twice as fast as creating (and
226	a completely new coroutine, so if you need a lot of generic coroutines in	225	destroying) a completely new coro, so if you need a lot of generic
227	quick successsion, use C<async_pool>, not C<async>.	226	coros in quick successsion, use C<async_pool>, not C<async>.
228		227
229	The code block is executed in an C<eval> context and a warning will be	228	The code block is executed in an C<eval> context and a warning will be
230	issued in case of an exception instead of terminating the program, as	229	issued in case of an exception instead of terminating the program, as
231	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	230	C<async> does. As the coro is being reused, stuff like C<on_destroy>
232	will not work in the expected way, unless you call terminate or cancel,	231	will not work in the expected way, unless you call terminate or cancel,
233	which somehow defeats the purpose of pooling (but is fine in the	232	which somehow defeats the purpose of pooling (but is fine in the
234	exceptional case).	233	exceptional case).
235		234
236	The priority will be reset to C<0> after each run, tracing will be	235	The priority will be reset to C<0> after each run, tracing will be
237	disabled, the description will be reset and the default output filehandle	236	disabled, the description will be reset and the default output filehandle
238	gets restored, so you can change all these. Otherwise the coroutine will	237	gets restored, so you can change all these. Otherwise the coro will
239	be re-used "as-is": most notably if you change other per-coroutine global	238	be re-used "as-is": most notably if you change other per-coro global
240	stuff such as C<$/> you I<must needs> to revert that change, which is most	239	stuff such as C<$/> you I<must needs> revert that change, which is most
241	simply done by using local as in: C< local $/ >.	240	simply done by using local as in: C<< local $/ >>.
242		241
243	The pool size is limited to C<8> idle coroutines (this can be adjusted by	242	The idle pool size is limited to C<8> idle coros (this can be
244	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	243	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
245	required.	244	coros as required.
246		245
247	If you are concerned about pooled coroutines growing a lot because a	246	If you are concerned about pooled coros growing a lot because a
248	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	247	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
249	{ terminate }> once per second or so to slowly replenish the pool. In	248	{ terminate }> once per second or so to slowly replenish the pool. In
250	addition to that, when the stacks used by a handler grows larger than 16kb	249	addition to that, when the stacks used by a handler grows larger than 32kb
251	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
252		251
253	=cut	252	=cut
254		253
255	our $POOL_SIZE = 8;	254	our $POOL_SIZE = 8;
256	our $POOL_RSS = 16 * 1024;	255	our $POOL_RSS = 32 * 1024;
257	our @async_pool;	256	our @async_pool;
258		257
259	sub pool_handler {	258	sub pool_handler {
260	my $cb;
261
262	while () {	259	while () {
263	eval {	260	eval {
264	while () {	261	&{&_pool_handler} while 1;
265	_pool_1 $cb;
266	&$cb;
267	_pool_2 $cb;
268	&schedule;
269	}
270	};	262	};
271		263
272	if ($@) {
273	last if $@ eq "\3async_pool terminate\2\n";
274	warn $@;	264	warn $@ if $@;
275	}
276	}	265	}
277	}	266	}
278		267
279	sub async_pool(&@) {
280	# this is also inlined into the unlock_scheduler
281	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
282
283	$coro->{_invoke} = [@_];
284	$coro->ready;
285
286	$coro
287	}
288
289	=back	268	=back
290		269
291	=head2 STATIC METHODS	270	=head1 STATIC METHODS
292		271
293	Static methods are actually functions that operate on the current coroutine.	272	Static methods are actually functions that implicitly operate on the
		273	current coro.
294		274
295	=over 4	275	=over 4
296		276
297	=item schedule	277	=item schedule
298		278
299	Calls the scheduler. The scheduler will find the next coroutine that is	279	Calls the scheduler. The scheduler will find the next coro that is
300	to be run from the ready queue and switches to it. The next coroutine	280	to be run from the ready queue and switches to it. The next coro
301	to be run is simply the one with the highest priority that is longest	281	to be run is simply the one with the highest priority that is longest
302	in its ready queue. If there is no coroutine ready, it will clal the	282	in its ready queue. If there is no coro ready, it will clal the
303	C<$Coro::idle> hook.	283	C<$Coro::idle> hook.
304		284
305	Please note that the current coroutine will I<not> be put into the ready	285	Please note that the current coro will I<not> be put into the ready
306	queue, so calling this function usually means you will never be called	286	queue, so calling this function usually means you will never be called
307	again unless something else (e.g. an event handler) calls C<< ->ready >>,	287	again unless something else (e.g. an event handler) calls C<< ->ready >>,
308	thus waking you up.	288	thus waking you up.
309		289
310	This makes C<schedule> I<the> generic method to use to block the current	290	This makes C<schedule> I<the> generic method to use to block the current
311	coroutine and wait for events: first you remember the current coroutine in	291	coro and wait for events: first you remember the current coro in
312	a variable, then arrange for some callback of yours to call C<< ->ready	292	a variable, then arrange for some callback of yours to call C<< ->ready
313	>> on that once some event happens, and last you call C<schedule> to put	293	>> on that once some event happens, and last you call C<schedule> to put
314	yourself to sleep. Note that a lot of things can wake your coroutine up,	294	yourself to sleep. Note that a lot of things can wake your coro up,
315	so you need to check whether the event indeed happened, e.g. by storing the	295	so you need to check whether the event indeed happened, e.g. by storing the
316	status in a variable.	296	status in a variable.
317		297
318	The canonical way to wait on external events is this:	298	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
319		299
320	{	300	=item cede
321	# remember current coroutine
322	my $current = $Coro::current;
323		301
324	# register a hypothetical event handler	302	"Cede" to other coros. This function puts the current coro into
325	on_event_invoke sub {	303	the ready queue and calls C<schedule>, which has the effect of giving
326	# wake up sleeping coroutine	304	up the current "timeslice" to other coros of the same or higher
327	$current->ready;	305	priority. Once your coro gets its turn again it will automatically be
328	undef $current;	306	resumed.
		307
		308	This function is often called C<yield> in other languages.
		309
		310	=item Coro::cede_notself
		311
		312	Works like cede, but is not exported by default and will cede to I<any>
		313	coro, regardless of priority. This is useful sometimes to ensure
		314	progress is made.
		315
		316	=item terminate [arg...]
		317
		318	Terminates the current coro with the given status values (see L<cancel>).
		319
		320	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		321
		322	These function install enter and leave winders in the current scope. The
		323	enter block will be executed when on_enter is called and whenever the
		324	current coro is re-entered by the scheduler, while the leave block is
		325	executed whenever the current coro is blocked by the scheduler, and
		326	also when the containing scope is exited (by whatever means, be it exit,
		327	die, last etc.).
		328
		329	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		330	BLOCKs>. That means: do not even think about calling C<die> without an
		331	eval, and do not even think of entering the scheduler in any way.
		332
		333	Since both BLOCKs are tied to the current scope, they will automatically
		334	be removed when the current scope exits.
		335
		336	These functions implement the same concept as C<dynamic-wind> in scheme
		337	does, and are useful when you want to localise some resource to a specific
		338	coro.
		339
		340	They slow down coro switching considerably for coros that use
		341	them (But coro switching is still reasonably fast if the handlers are
		342	fast).
		343
		344	These functions are best understood by an example: The following function
		345	will change the current timezone to "Antarctica/South_Pole", which
		346	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		347	which remember/change the current timezone and restore the previous
		348	value, respectively, the timezone is only changes for the coro that
		349	installed those handlers.
		350
		351	use POSIX qw(tzset);
		352
		353	async {
		354	my $old_tz; # store outside TZ value here
		355
		356	Coro::on_enter {
		357	$old_tz = $ENV{TZ}; # remember the old value
		358
		359	$ENV{TZ} = "Antarctica/South_Pole";
		360	tzset; # enable new value
329	};	361	};
330		362
331	# call schedule until event occurred.	363	Coro::on_leave {
332	# in case we are woken up for other reasons	364	$ENV{TZ} = $old_tz;
333	# (current still defined), loop.	365	tzset; # restore old value
334	Coro::schedule while $current;	366	};
		367
		368	# at this place, the timezone is Antarctica/South_Pole,
		369	# without disturbing the TZ of any other coro.
335	}	370	};
336		371
337	=item cede	372	This can be used to localise about any resource (locale, uid, current
338		373	working directory etc.) to a block, despite the existance of other
339	"Cede" to other coroutines. This function puts the current coroutine into	374	coros.
340	the ready queue and calls C<schedule>, which has the effect of giving
341	up the current "timeslice" to other coroutines of the same or higher
342	priority. Once your coroutine gets its turn again it will automatically be
343	resumed.
344
345	This function is often called C<yield> in other languages.
346
347	=item Coro::cede_notself
348
349	Works like cede, but is not exported by default and will cede to I<any>
350	coroutine, regardless of priority. This is useful sometimes to ensure
351	progress is made.
352
353	=item terminate [arg...]
354
355	Terminates the current coroutine with the given status values (see L<cancel>).
356		375
357	=item killall	376	=item killall
358		377
359	Kills/terminates/cancels all coroutines except the currently running	378	Kills/terminates/cancels all coros except the currently running one.
360	one. This is useful after a fork, either in the child or the parent, as
361	usually only one of them should inherit the running coroutines.
362		379
363	Note that while this will try to free some of the main programs resources,	380	Note that while this will try to free some of the main interpreter
		381	resources if the calling coro isn't the main coro, but one
364	you cannot free all of them, so if a coroutine that is not the main	382	cannot free all of them, so if a coro that is not the main coro
365	program calls this function, there will be some one-time resource leak.	383	calls this function, there will be some one-time resource leak.
366		384
367	=cut	385	=cut
368
369	sub terminate {
370	$current->cancel (@_);
371	}
372		386
373	sub killall {	387	sub killall {
374	for (Coro::State::list) {	388	for (Coro::State::list) {
375	$_->cancel	389	$_->cancel
376	if $_ != $current && UNIVERSAL::isa $_, "Coro";	390	if $_ != $current && UNIVERSAL::isa $_, "Coro";
377	}	391	}
378	}	392	}
379		393
380	=back	394	=back
381		395
382	=head2 COROUTINE METHODS	396	=head1 CORO OBJECT METHODS
383		397
384	These are the methods you can call on coroutine objects (or to create	398	These are the methods you can call on coro objects (or to create
385	them).	399	them).
386		400
387	=over 4	401	=over 4
388		402
389	=item new Coro \&sub [, @args...]	403	=item new Coro \&sub [, @args...]
390		404
391	Create a new coroutine and return it. When the sub returns, the coroutine	405	Create a new coro and return it. When the sub returns, the coro
392	automatically terminates as if C<terminate> with the returned values were	406	automatically terminates as if C<terminate> with the returned values were
393	called. To make the coroutine run you must first put it into the ready	407	called. To make the coro run you must first put it into the ready
394	queue by calling the ready method.	408	queue by calling the ready method.
395		409
396	See C<async> and C<Coro::State::new> for additional info about the	410	See C<async> and C<Coro::State::new> for additional info about the
397	coroutine environment.	411	coro environment.
398		412
399	=cut	413	=cut
400		414
401	sub _run_coro {	415	sub _coro_run {
402	terminate &{+shift};	416	terminate &{+shift};
403	}	417	}
404		418
405	sub new {
406	my $class = shift;
407
408	$class->SUPER::new (\&_run_coro, @_)
409	}
410
411	=item $success = $coroutine->ready	419	=item $success = $coro->ready
412		420
413	Put the given coroutine into the end of its ready queue (there is one	421	Put the given coro into the end of its ready queue (there is one
414	queue for each priority) and return true. If the coroutine is already in	422	queue for each priority) and return true. If the coro is already in
415	the ready queue, do nothing and return false.	423	the ready queue, do nothing and return false.
416		424
417	This ensures that the scheduler will resume this coroutine automatically	425	This ensures that the scheduler will resume this coro automatically
418	once all the coroutines of higher priority and all coroutines of the same	426	once all the coro of higher priority and all coro of the same
419	priority that were put into the ready queue earlier have been resumed.	427	priority that were put into the ready queue earlier have been resumed.
420		428
421	=item $is_ready = $coroutine->is_ready	429	=item $is_ready = $coro->is_ready
422		430
423	Return whether the coroutine is currently the ready queue or not,	431	Returns true iff the Coro object is in the ready queue. Unless the Coro
		432	object gets destroyed, it will eventually be scheduled by the scheduler.
424		433
		434	=item $is_running = $coro->is_running
		435
		436	Returns true iff the Coro object is currently running. Only one Coro object
		437	can ever be in the running state (but it currently is possible to have
		438	multiple running Coro::States).
		439
		440	=item $is_suspended = $coro->is_suspended
		441
		442	Returns true iff this Coro object has been suspended. Suspended Coros will
		443	not ever be scheduled.
		444
425	=item $coroutine->cancel (arg...)	445	=item $coro->cancel (arg...)
426		446
427	Terminates the given coroutine and makes it return the given arguments as	447	Terminates the given Coro and makes it return the given arguments as
428	status (default: the empty list). Never returns if the coroutine is the	448	status (default: the empty list). Never returns if the Coro is the
429	current coroutine.	449	current Coro.
430		450
431	=cut	451	=cut
432		452
433	sub cancel {	453	sub cancel {
434	my $self = shift;	454	my $self = shift;
435	$self->{_status} = [@_];
436		455
437	if ($current == $self) {	456	if ($current == $self) {
438	push @destroy, $self;	457	terminate @_;
439	$manager->ready;
440	&schedule while 1;
441	} else {	458	} else {
442	$self->_cancel;	459	$self->{_status} = [@_];
		460	Coro::State::cancel $self;
443	}	461	}
444	}	462	}
445		463
		464	=item $coro->schedule_to
		465
		466	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		467	of continuing with the next coro from the ready queue, always switch to
		468	the given coro object (regardless of priority etc.). The readyness
		469	state of that coro isn't changed.
		470
		471	This is an advanced method for special cases - I'd love to hear about any
		472	uses for this one.
		473
		474	=item $coro->cede_to
		475
		476	Like C<schedule_to>, but puts the current coro into the ready
		477	queue. This has the effect of temporarily switching to the given
		478	coro, and continuing some time later.
		479
		480	This is an advanced method for special cases - I'd love to hear about any
		481	uses for this one.
		482
		483	=item $coro->throw ([$scalar])
		484
		485	If C<$throw> is specified and defined, it will be thrown as an exception
		486	inside the coro at the next convenient point in time. Otherwise
		487	clears the exception object.
		488
		489	Coro will check for the exception each time a schedule-like-function
		490	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		491	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		492	detect this case and return early in case an exception is pending.
		493
		494	The exception object will be thrown "as is" with the specified scalar in
		495	C<$@>, i.e. if it is a string, no line number or newline will be appended
		496	(unlike with C<die>).
		497
		498	This can be used as a softer means than C<cancel> to ask a coro to
		499	end itself, although there is no guarantee that the exception will lead to
		500	termination, and if the exception isn't caught it might well end the whole
		501	program.
		502
		503	You might also think of C<throw> as being the moral equivalent of
		504	C<kill>ing a coro with a signal (in this case, a scalar).
		505
446	=item $coroutine->join	506	=item $coro->join
447		507
448	Wait until the coroutine terminates and return any values given to the	508	Wait until the coro terminates and return any values given to the
449	C<terminate> or C<cancel> functions. C<join> can be called concurrently	509	C<terminate> or C<cancel> functions. C<join> can be called concurrently
450	from multiple coroutines, and all will be resumed and given the status	510	from multiple coro, and all will be resumed and given the status
451	return once the C<$coroutine> terminates.	511	return once the C<$coro> terminates.
452		512
453	=cut	513	=cut
454		514
455	sub join {	515	sub join {
456	my $self = shift;	516	my $self = shift;
…		…
467	}	527	}
468		528
469	wantarray ? @{$self->{_status}} : $self->{_status}[0];	529	wantarray ? @{$self->{_status}} : $self->{_status}[0];
470	}	530	}
471		531
472	=item $coroutine->on_destroy (\&cb)	532	=item $coro->on_destroy (\&cb)
473		533
474	Registers a callback that is called when this coroutine gets destroyed,	534	Registers a callback that is called when this coro gets destroyed,
475	but before it is joined. The callback gets passed the terminate arguments,	535	but before it is joined. The callback gets passed the terminate arguments,
476	if any, and I<must not> die, under any circumstances.	536	if any, and I<must not> die, under any circumstances.
477		537
478	=cut	538	=cut
479		539
…		…
481	my ($self, $cb) = @_;	541	my ($self, $cb) = @_;
482		542
483	push @{ $self->{_on_destroy} }, $cb;	543	push @{ $self->{_on_destroy} }, $cb;
484	}	544	}
485		545
486	=item $oldprio = $coroutine->prio ($newprio)	546	=item $oldprio = $coro->prio ($newprio)
487		547
488	Sets (or gets, if the argument is missing) the priority of the	548	Sets (or gets, if the argument is missing) the priority of the
489	coroutine. Higher priority coroutines get run before lower priority	549	coro. Higher priority coro get run before lower priority
490	coroutines. Priorities are small signed integers (currently -4 .. +3),	550	coro. Priorities are small signed integers (currently -4 .. +3),
491	that you can refer to using PRIO_xxx constants (use the import tag :prio	551	that you can refer to using PRIO_xxx constants (use the import tag :prio
492	to get then):	552	to get then):
493		553
494	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	554	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
495	3 > 1 > 0 > -1 > -3 > -4	555	3 > 1 > 0 > -1 > -3 > -4
496		556
497	# set priority to HIGH	557	# set priority to HIGH
498	current->prio(PRIO_HIGH);	558	current->prio (PRIO_HIGH);
499		559
500	The idle coroutine ($Coro::idle) always has a lower priority than any	560	The idle coro ($Coro::idle) always has a lower priority than any
501	existing coroutine.	561	existing coro.
502		562
503	Changing the priority of the current coroutine will take effect immediately,	563	Changing the priority of the current coro will take effect immediately,
504	but changing the priority of coroutines in the ready queue (but not	564	but changing the priority of coro in the ready queue (but not
505	running) will only take effect after the next schedule (of that	565	running) will only take effect after the next schedule (of that
506	coroutine). This is a bug that will be fixed in some future version.	566	coro). This is a bug that will be fixed in some future version.
507		567
508	=item $newprio = $coroutine->nice ($change)	568	=item $newprio = $coro->nice ($change)
509		569
510	Similar to C<prio>, but subtract the given value from the priority (i.e.	570	Similar to C<prio>, but subtract the given value from the priority (i.e.
511	higher values mean lower priority, just as in unix).	571	higher values mean lower priority, just as in unix).
512		572
513	=item $olddesc = $coroutine->desc ($newdesc)	573	=item $olddesc = $coro->desc ($newdesc)
514		574
515	Sets (or gets in case the argument is missing) the description for this	575	Sets (or gets in case the argument is missing) the description for this
516	coroutine. This is just a free-form string you can associate with a coroutine.	576	coro. This is just a free-form string you can associate with a
		577	coro.
517		578
518	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	579	This method simply sets the C<< $coro->{desc} >> member to the given
519	can modify this member directly if you wish.	580	string. You can modify this member directly if you wish.
520
521	=item $coroutine->throw ([$scalar])
522
523	If C<$throw> is specified and defined, it will be thrown as an exception
524	inside the coroutine at the next convinient point in time (usually after
525	it gains control at the next schedule/transfer/cede). Otherwise clears the
526	exception object.
527
528	The exception object will be thrown "as is" with the specified scalar in
529	C<$@>, i.e. if it is a string, no line number or newline will be appended
530	(unlike with C<die>).
531
532	This can be used as a softer means than C<cancel> to ask a coroutine to
533	end itself, although there is no guarentee that the exception will lead to
534	termination, and if the exception isn't caught it might well end the whole
535	program.
536		581
537	=cut	582	=cut
538		583
539	sub desc {	584	sub desc {
540	my $old = $_[0]{desc};	585	my $old = $_[0]{desc};
541	$_[0]{desc} = $_[1] if @_ > 1;	586	$_[0]{desc} = $_[1] if @_ > 1;
542	$old;	587	$old;
543	}	588	}
544		589
		590	sub transfer {
		591	require Carp;
		592	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		593	}
		594
545	=back	595	=back
546		596
547	=head2 GLOBAL FUNCTIONS	597	=head1 GLOBAL FUNCTIONS
548		598
549	=over 4	599	=over 4
550		600
551	=item Coro::nready	601	=item Coro::nready
552		602
553	Returns the number of coroutines that are currently in the ready state,	603	Returns the number of coro that are currently in the ready state,
554	i.e. that can be switched to by calling C<schedule> directory or	604	i.e. that can be switched to by calling C<schedule> directory or
555	indirectly. The value C<0> means that the only runnable coroutine is the	605	indirectly. The value C<0> means that the only runnable coro is the
556	currently running one, so C<cede> would have no effect, and C<schedule>	606	currently running one, so C<cede> would have no effect, and C<schedule>
557	would cause a deadlock unless there is an idle handler that wakes up some	607	would cause a deadlock unless there is an idle handler that wakes up some
558	coroutines.	608	coro.
559		609
560	=item my $guard = Coro::guard { ... }	610	=item my $guard = Coro::guard { ... }
561		611
562	This creates and returns a guard object. Nothing happens until the object	612	This function still exists, but is deprecated. Please use the
563	gets destroyed, in which case the codeblock given as argument will be	613	C<Guard::guard> function instead.
564	executed. This is useful to free locks or other resources in case of a
565	runtime error or when the coroutine gets canceled, as in both cases the
566	guard block will be executed. The guard object supports only one method,
567	C<< ->cancel >>, which will keep the codeblock from being executed.
568		614
569	Example: set some flag and clear it again when the coroutine gets canceled
570	or the function returns:
571
572	sub do_something {
573	my $guard = Coro::guard { $busy = 0 };
574	$busy = 1;
575
576	# do something that requires $busy to be true
577	}
578
579	=cut	615	=cut
580		616
581	sub guard(&) {	617	BEGIN { *guard = \&Guard::guard }
582	bless \(my $cb = $_[0]), "Coro::guard"
583	}
584
585	sub Coro::guard::cancel {
586	${$_[0]} = sub { };
587	}
588
589	sub Coro::guard::DESTROY {
590	${$_[0]}->();
591	}
592
593		618
594	=item unblock_sub { ... }	619	=item unblock_sub { ... }
595		620
596	This utility function takes a BLOCK or code reference and "unblocks" it,	621	This utility function takes a BLOCK or code reference and "unblocks" it,
597	returning a new coderef. Unblocking means that calling the new coderef	622	returning a new coderef. Unblocking means that calling the new coderef
598	will return immediately without blocking, returning nothing, while the	623	will return immediately without blocking, returning nothing, while the
599	original code ref will be called (with parameters) from within another	624	original code ref will be called (with parameters) from within another
600	coroutine.	625	coro.
601		626
602	The reason this function exists is that many event libraries (such as the	627	The reason this function exists is that many event libraries (such as the
603	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	628	venerable L<Event\|Event> module) are not thread-safe (a weaker form
604	of thread-safety). This means you must not block within event callbacks,	629	of reentrancy). This means you must not block within event callbacks,
605	otherwise you might suffer from crashes or worse. The only event library	630	otherwise you might suffer from crashes or worse. The only event library
606	currently known that is safe to use without C<unblock_sub> is L<EV>.	631	currently known that is safe to use without C<unblock_sub> is L<EV>.
607		632
608	This function allows your callbacks to block by executing them in another	633	This function allows your callbacks to block by executing them in another
609	coroutine where it is safe to block. One example where blocking is handy	634	coro where it is safe to block. One example where blocking is handy
610	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	635	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
611	disk, for example.	636	disk, for example.
612		637
613	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	638	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
614	creating event callbacks that want to block.	639	creating event callbacks that want to block.
615		640
616	If your handler does not plan to block (e.g. simply sends a message to	641	If your handler does not plan to block (e.g. simply sends a message to
617	another coroutine, or puts some other coroutine into the ready queue),	642	another coro, or puts some other coro into the ready queue), there is
618	there is no reason to use C<unblock_sub>.	643	no reason to use C<unblock_sub>.
619		644
620	Note that you also need to use C<unblock_sub> for any other callbacks that	645	Note that you also need to use C<unblock_sub> for any other callbacks that
621	are indirectly executed by any C-based event loop. For example, when you	646	are indirectly executed by any C-based event loop. For example, when you
622	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it	647	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
623	provides callbacks that are the result of some event callback, then you	648	provides callbacks that are the result of some event callback, then you
…		…
632	# return immediately and can be reused) and because we cannot cede	657	# return immediately and can be reused) and because we cannot cede
633	# inside an event callback.	658	# inside an event callback.
634	our $unblock_scheduler = new Coro sub {	659	our $unblock_scheduler = new Coro sub {
635	while () {	660	while () {
636	while (my $cb = pop @unblock_queue) {	661	while (my $cb = pop @unblock_queue) {
637	# this is an inlined copy of async_pool	662	&async_pool (@$cb);
638	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
639		663
640	$coro->{_invoke} = $cb;
641	$coro->ready;
642	cede; # for short-lived callbacks, this reduces pressure on the coro pool	664	# for short-lived callbacks, this reduces pressure on the coro pool
		665	# as the chance is very high that the async_poll coro will be back
		666	# in the idle state when cede returns
		667	cede;
643	}	668	}
644	schedule; # sleep well	669	schedule; # sleep well
645	}	670	}
646	};	671	};
647	$unblock_scheduler->desc ("[unblock_sub scheduler]");	672	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
648		673
649	sub unblock_sub(&) {	674	sub unblock_sub(&) {
650	my $cb = shift;	675	my $cb = shift;
651		676
652	sub {	677	sub {
653	unshift @unblock_queue, [$cb, @_];	678	unshift @unblock_queue, [$cb, @_];
654	$unblock_scheduler->ready;	679	$unblock_scheduler->ready;
655	}	680	}
656	}	681	}
657		682
		683	=item $cb = Coro::rouse_cb
		684
		685	Create and return a "rouse callback". That's a code reference that,
		686	when called, will remember a copy of its arguments and notify the owner
		687	coro of the callback.
		688
		689	See the next function.
		690
		691	=item @args = Coro::rouse_wait [$cb]
		692
		693	Wait for the specified rouse callback (or the last one that was created in
		694	this coro).
		695
		696	As soon as the callback is invoked (or when the callback was invoked
		697	before C<rouse_wait>), it will return the arguments originally passed to
		698	the rouse callback.
		699
		700	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		701
658	=back	702	=back
659		703
660	=cut	704	=cut
661		705
662	1;	706	1;
663		707
		708	=head1 HOW TO WAIT FOR A CALLBACK
		709
		710	It is very common for a coro to wait for some callback to be
		711	called. This occurs naturally when you use coro in an otherwise
		712	event-based program, or when you use event-based libraries.
		713
		714	These typically register a callback for some event, and call that callback
		715	when the event occured. In a coro, however, you typically want to
		716	just wait for the event, simplyifying things.
		717
		718	For example C<< AnyEvent->child >> registers a callback to be called when
		719	a specific child has exited:
		720
		721	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		722
		723	But from within a coro, you often just want to write this:
		724
		725	my $status = wait_for_child $pid;
		726
		727	Coro offers two functions specifically designed to make this easy,
		728	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		729
		730	The first function, C<rouse_cb>, generates and returns a callback that,
		731	when invoked, will save its arguments and notify the coro that
		732	created the callback.
		733
		734	The second function, C<rouse_wait>, waits for the callback to be called
		735	(by calling C<schedule> to go to sleep) and returns the arguments
		736	originally passed to the callback.
		737
		738	Using these functions, it becomes easy to write the C<wait_for_child>
		739	function mentioned above:
		740
		741	sub wait_for_child($) {
		742	my ($pid) = @_;
		743
		744	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		745
		746	my ($rpid, $rstatus) = Coro::rouse_wait;
		747	$rstatus
		748	}
		749
		750	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		751	you can roll your own, using C<schedule>:
		752
		753	sub wait_for_child($) {
		754	my ($pid) = @_;
		755
		756	# store the current coro in $current,
		757	# and provide result variables for the closure passed to ->child
		758	my $current = $Coro::current;
		759	my ($done, $rstatus);
		760
		761	# pass a closure to ->child
		762	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		763	$rstatus = $_[1]; # remember rstatus
		764	$done = 1; # mark $rstatus as valud
		765	});
		766
		767	# wait until the closure has been called
		768	schedule while !$done;
		769
		770	$rstatus
		771	}
		772
		773
664	=head1 BUGS/LIMITATIONS	774	=head1 BUGS/LIMITATIONS
665		775
		776	=over 4
		777
		778	=item fork with pthread backend
		779
		780	When Coro is compiled using the pthread backend (which isn't recommended
		781	but required on many BSDs as their libcs are completely broken), then
		782	coro will not survive a fork. There is no known workaround except to
		783	fix your libc and use a saner backend.
		784
		785	=item perl process emulation ("threads")
		786
666	This module is not perl-pseudo-thread-safe. You should only ever use this	787	This module is not perl-pseudo-thread-safe. You should only ever use this
667	module from the same thread (this requirement might be removed in the	788	module from the first thread (this requirement might be removed in the
668	future to allow per-thread schedulers, but Coro::State does not yet allow	789	future to allow per-thread schedulers, but Coro::State does not yet allow
669	this). I recommend disabling thread support and using processes, as this	790	this). I recommend disabling thread support and using processes, as having
670	is much faster and uses less memory.	791	the windows process emulation enabled under unix roughly halves perl
		792	performance, even when not used.
		793
		794	=item coro switching is not signal safe
		795
		796	You must not switch to another coro from within a signal handler
		797	(only relevant with %SIG - most event libraries provide safe signals).
		798
		799	That means you I<MUST NOT> call any function that might "block" the
		800	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		801	anything that calls those. Everything else, including calling C<ready>,
		802	works.
		803
		804	=back
		805
671		806
672	=head1 SEE ALSO	807	=head1 SEE ALSO
673		808
674	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.	809	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
675		810
676	Debugging: L<Coro::Debug>.	811	Debugging: L<Coro::Debug>.
677		812
678	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	813	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
679		814
680	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	815	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		816	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
681		817
682	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.	818	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
683		819
684	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.	820	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		821	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		822	L<Coro::Select>.
685		823
686	XS API: L<Coro::MakeMaker>.	824	XS API: L<Coro::MakeMaker>.
687		825
688	Low level Configuration, Coroutine Environment: L<Coro::State>.	826	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
689		827
690	=head1 AUTHOR	828	=head1 AUTHOR
691		829
692	Marc Lehmann <schmorp@schmorp.de>	830	Marc Lehmann <schmorp@schmorp.de>
693	http://home.schmorp.de/	831	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs. Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.202 by root, Tue Sep 30 17:12:34 2008 UTC vs.
Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC