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

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Revision 1.181 by root, Fri May 9 22:04:37 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	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
31	threads but don't (in general) run in parallel at the same time even	32	manpage. This manpage mainly contains reference information.
32	on SMP machines. The specific flavor of coroutine used in this module
33	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much
36	safer and easier than threads programming.
37		33
38	Unlike a normal perl program, however, coroutines allow you to have	34	This module collection manages continuations in general, most often in
39	multiple running interpreters that share data, which is especially useful	35	the form of cooperative threads (also called coros, or simply "coro"
40	to code pseudo-parallel processes, such as multiple HTTP-GET requests	36	in the documentation). They are similar to kernel threads but don't (in
41	running concurrently.	37	general) run in parallel at the same time even on SMP machines. The
		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.
42		43
43	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
44	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
45	emulation coming from the Windows platform: On standard operating systems	46	full shared address space, which makes communication between threads
46	they serve no purpose whatsoever, except by making your programs slow and	47	very easy. And threads are fast, too: disabling the Windows process
47	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
48	aks your software vendor/distributor to do it for you).	49	four times speed increase for your programs.
49		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
50	In this module, coroutines are defined as "callchain + lexical variables +	57	In this module, a thread is defined as "callchain + lexical variables +
51	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	58	@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,
52	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
53	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.
54		64
55	=cut	65	=cut
56		66
57	package Coro;	67	package Coro;
58		68
59	use strict;	69	use strict qw(vars subs);
60	no warnings "uninitialized";	70	no warnings "uninitialized";
61		71
		72	use Guard ();
		73
62	use Coro::State;	74	use Coro::State;
63		75
64	use base qw(Coro::State Exporter);	76	use base qw(Coro::State Exporter);
65		77
66	our $idle; # idle handler	78	our $idle; # idle handler
67	our $main; # main coroutine	79	our $main; # main coro
68	our $current; # current coroutine	80	our $current; # current coro
69		81
70	our $VERSION = 4.6;	82	our $VERSION = 5.13;
71		83
72	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	84	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
73	our %EXPORT_TAGS = (	85	our %EXPORT_TAGS = (
74	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	86	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
75	);	87	);
76	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	88	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
77		89
		90	=head1 GLOBAL VARIABLES
		91
78	=over 4	92	=over 4
79		93
80	=item $Coro::main	94	=item $Coro::main
81		95
82	This variable stores the coroutine object that represents the main	96	This variable stores the Coro object that represents the main
83	program. While you cna C<ready> it and do most other things you can do to	97	program. While you cna C<ready> it and do most other things you can do to
84	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	98	coro, it is mainly useful to compare again C<$Coro::current>, to see
85	wether you are running in the main program or not.	99	whether you are running in the main program or not.
86		100
87	=cut	101	=cut
88		102
89	$main = new Coro;	103	# $main is now being initialised by Coro::State
90		104
91	=item $Coro::current	105	=item $Coro::current
92		106
93	The coroutine object representing the current coroutine (the last	107	The Coro object representing the current coro (the last
94	coroutine that the Coro scheduler switched to). The initial value is	108	coro that the Coro scheduler switched to). The initial value is
95	C<$main> (of course).	109	C<$Coro::main> (of course).
96		110
97	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
98	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
99	not otherwise modify the variable itself.	113	not otherwise modify the variable itself.
100		114
101	=cut	115	=cut
102		116
103	$main->{desc} = "[main::]";
104
105	# maybe some other module used Coro::Specific before...
106	$main->{_specific} = $current->{_specific}
107	if $current;
108
109	_set_current $main;
110
111	sub current() { $current } # [DEPRECATED]	117	sub current() { $current } # [DEPRECATED]
112		118
113	=item $Coro::idle	119	=item $Coro::idle
114		120
115	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
116	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
117	pretty low-level functionality.	123	pretty low-level functionality.
118		124
119	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
120	finds no ready coroutines to run. The default implementation prints	128	ready coros to run. The default implementation prints "FATAL:
121	"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
122	to continue.	130	continue.
123		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
124	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
125	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
126	coroutine so the scheduler can run it.	138	coro so the scheduler can run it.
127		139
128	Note that the callback I<must not>, under any circumstances, block	140	Note that the callback I<must not>, under any circumstances, block
129	the current coroutine. Normally, this is achieved by having an "idle	141	the current coro. Normally, this is achieved by having an "idle
130	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
131	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.
132		145
133	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
134	technique.	147	technique.
135		148
136	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
…		…
141	$idle = sub {	154	$idle = sub {
142	require Carp;	155	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	156	Carp::croak ("FATAL: deadlock detected");
144	};	157	};
145		158
146	sub _cancel {
147	my ($self) = @_;
148
149	# free coroutine data and mark as destructed
150	$self->_destroy
151	or return;
152
153	# call all destruction callbacks
154	$_->(@{$self->{_status}})
155	for @{(delete $self->{_on_destroy}) \|\| []};
156	}
157
158	# this coroutine is necessary because a coroutine	159	# this coro is necessary because a coro
159	# cannot destroy itself.	160	# cannot destroy itself.
160	my @destroy;	161	our @destroy;
161	my $manager;	162	our $manager;
162		163
163	$manager = new Coro sub {	164	$manager = new Coro sub {
164	while () {	165	while () {
165	(shift @destroy)->_cancel	166	Coro::State::cancel shift @destroy
166	while @destroy;	167	while @destroy;
167		168
168	&schedule;	169	&schedule;
169	}	170	}
170	};	171	};
171	$manager->desc ("[coro manager]");	172	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	173	$manager->prio (PRIO_MAX);
173		174
174	=back	175	=back
175		176
176	=head2 SIMPLE COROUTINE CREATION	177	=head1 SIMPLE CORO CREATION
177		178
178	=over 4	179	=over 4
179		180
180	=item async { ... } [@args...]	181	=item async { ... } [@args...]
181		182
182	Create a new coroutine and return it's coroutine object (usually	183	Create a new coro and return its Coro object (usually
183	unused). The coroutine will be put into the ready queue, so	184	unused). The coro will be put into the ready queue, so
184	it will start running automatically on the next scheduler run.	185	it will start running automatically on the next scheduler run.
185		186
186	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
187	coroutine. When it returns argument returns the coroutine is automatically	188	coro. When it returns argument returns the coro is automatically
188	terminated.	189	terminated.
189		190
190	The remaining arguments are passed as arguments to the closure.	191	The remaining arguments are passed as arguments to the closure.
191		192
192	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
193	environment in which coroutines are executed.	194	environment in which coro are executed.
194		195
195	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
196	the coroutine. Likewise, when the coroutine dies, the program will exit,	197	the coro. Likewise, when the coro dies, the program will exit,
197	just as it would in the main program.	198	just as it would in the main program.
198		199
199	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
200	simply avoid dieing (by use of C<eval>).	201	simply avoid dieing (by use of C<eval>).
201		202
202	Example: Create a new coroutine that just prints its arguments.	203	Example: Create a new coro that just prints its arguments.
203		204
204	async {	205	async {
205	print "@_\n";	206	print "@_\n";
206	} 1,2,3,4;	207	} 1,2,3,4;
207		208
…		…
213	$coro	214	$coro
214	}	215	}
215		216
216	=item async_pool { ... } [@args...]	217	=item async_pool { ... } [@args...]
217		218
218	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
219	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
220	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
221	or bad :).	222	or bad :).
222		223
223	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
224	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
225	quick successsion, use C<async_pool>, not C<async>.	226	coros in quick successsion, use C<async_pool>, not C<async>.
226		227
227	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
228	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
229	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>
230	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,
231	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
232	exceptional case).	233	exceptional case).
233		234
234	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
235	disabled, the description will be reset and the default output filehandle	236	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	gets restored, so you can change all these. Otherwise the coro will
237	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
238	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
239	simply done by using local as in: C< local $/ >.	240	simply done by using local as in: C<< local $/ >>.
240		241
241	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
242	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
243	required.	244	coros as required.
244		245
245	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
246	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
247	{ 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
248	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
249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
250		251
251	=cut	252	=cut
252		253
253	our $POOL_SIZE = 8;	254	our $POOL_SIZE = 8;
254	our $POOL_RSS = 16 * 1024;	255	our $POOL_RSS = 32 * 1024;
255	our @async_pool;	256	our @async_pool;
256		257
257	sub pool_handler {	258	sub pool_handler {
258	my $cb;
259
260	while () {	259	while () {
261	eval {	260	eval {
262	while () {	261	&{&_pool_handler} while 1;
263	_pool_1 $cb;
264	&$cb;
265	_pool_2 $cb;
266	&schedule;
267	}
268	};	262	};
269		263
270	last if $@ eq "\3async_pool terminate\2\n";
271	warn $@ if $@;	264	warn $@ if $@;
272	}	265	}
273	}	266	}
274		267
275	sub async_pool(&@) {
276	# this is also inlined into the unlock_scheduler
277	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
278
279	$coro->{_invoke} = [@_];
280	$coro->ready;
281
282	$coro
283	}
284
285	=back	268	=back
286		269
287	=head2 STATIC METHODS	270	=head1 STATIC METHODS
288		271
289	Static methods are actually functions that operate on the current coroutine.	272	Static methods are actually functions that implicitly operate on the
		273	current coro.
290		274
291	=over 4	275	=over 4
292		276
293	=item schedule	277	=item schedule
294		278
295	Calls the scheduler. The scheduler will find the next coroutine that is	279	Calls the scheduler. The scheduler will find the next coro that is
296	to be run from the ready queue and switches to it. The next coroutine	280	to be run from the ready queue and switches to it. The next coro
297	to be run is simply the one with the highest priority that is longest	281	to be run is simply the one with the highest priority that is longest
298	in its ready queue. If there is no coroutine ready, it will clal the	282	in its ready queue. If there is no coro ready, it will clal the
299	C<$Coro::idle> hook.	283	C<$Coro::idle> hook.
300		284
301	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
302	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
303	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 >>,
304	thus waking you up.	288	thus waking you up.
305		289
306	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
307	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
308	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
309	>> 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
310	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,
311	so you need to check wether 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
312	status in a variable.	296	status in a variable.
313		297
314	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.
315		299
316	{	300	=item cede
317	# remember current coroutine
318	my $current = $Coro::current;
319		301
320	# register a hypothetical event handler	302	"Cede" to other coros. This function puts the current coro into
321	on_event_invoke sub {	303	the ready queue and calls C<schedule>, which has the effect of giving
322	# wake up sleeping coroutine	304	up the current "timeslice" to other coros of the same or higher
323	$current->ready;	305	priority. Once your coro gets its turn again it will automatically be
324	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
325	};	361	};
326		362
327	# call schedule until event occurred.	363	Coro::on_leave {
328	# in case we are woken up for other reasons	364	$ENV{TZ} = $old_tz;
329	# (current still defined), loop.	365	tzset; # restore old value
330	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.
331	}	370	};
332		371
333	=item cede	372	This can be used to localise about any resource (locale, uid, current
334		373	working directory etc.) to a block, despite the existance of other
335	"Cede" to other coroutines. This function puts the current coroutine into	374	coros.
336	the ready queue and calls C<schedule>, which has the effect of giving
337	up the current "timeslice" to other coroutines of the same or higher
338	priority. Once your coroutine gets its turn again it will automatically be
339	resumed.
340
341	This function is often called C<yield> in other languages.
342
343	=item Coro::cede_notself
344
345	Works like cede, but is not exported by default and will cede to I<any>
346	coroutine, regardless of priority. This is useful sometimes to ensure
347	progress is made.
348
349	=item terminate [arg...]
350
351	Terminates the current coroutine with the given status values (see L<cancel>).
352		375
353	=item killall	376	=item killall
354		377
355	Kills/terminates/cancels all coroutines except the currently running	378	Kills/terminates/cancels all coros except the currently running one.
356	one. This is useful after a fork, either in the child or the parent, as
357	usually only one of them should inherit the running coroutines.
358		379
359	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
360	you cnanot 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
361	program calls this function, there will be some one-time resource leak.	383	calls this function, there will be some one-time resource leak.
362		384
363	=cut	385	=cut
364
365	sub terminate {
366	$current->cancel (@_);
367	}
368		386
369	sub killall {	387	sub killall {
370	for (Coro::State::list) {	388	for (Coro::State::list) {
371	$_->cancel	389	$_->cancel
372	if $_ != $current && UNIVERSAL::isa $_, "Coro";	390	if $_ != $current && UNIVERSAL::isa $_, "Coro";
373	}	391	}
374	}	392	}
375		393
376	=back	394	=back
377		395
378	=head2 COROUTINE METHODS	396	=head1 CORO OBJECT METHODS
379		397
380	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
381	them).	399	them).
382		400
383	=over 4	401	=over 4
384		402
385	=item new Coro \&sub [, @args...]	403	=item new Coro \&sub [, @args...]
386		404
387	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
388	automatically terminates as if C<terminate> with the returned values were	406	automatically terminates as if C<terminate> with the returned values were
389	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
390	queue by calling the ready method.	408	queue by calling the ready method.
391		409
392	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
393	coroutine environment.	411	coro environment.
394		412
395	=cut	413	=cut
396		414
397	sub _run_coro {	415	sub _coro_run {
398	terminate &{+shift};	416	terminate &{+shift};
399	}	417	}
400		418
401	sub new {
402	my $class = shift;
403
404	$class->SUPER::new (\&_run_coro, @_)
405	}
406
407	=item $success = $coroutine->ready	419	=item $success = $coro->ready
408		420
409	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
410	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
411	the ready queue, do nothing and return false.	423	the ready queue, do nothing and return false.
412		424
413	This ensures that the scheduler will resume this coroutine automatically	425	This ensures that the scheduler will resume this coro automatically
414	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
415	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.
416		428
417	=item $is_ready = $coroutine->is_ready	429	=item $is_ready = $coro->is_ready
418		430
419	Return wether 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.
420		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
421	=item $coroutine->cancel (arg...)	445	=item $coro->cancel (arg...)
422		446
423	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
424	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
425	current coroutine.	449	current Coro.
426		450
427	=cut	451	=cut
428		452
429	sub cancel {	453	sub cancel {
430	my $self = shift;	454	my $self = shift;
431	$self->{_status} = [@_];
432		455
433	if ($current == $self) {	456	if ($current == $self) {
434	push @destroy, $self;	457	terminate @_;
435	$manager->ready;
436	&schedule while 1;
437	} else {	458	} else {
438	$self->_cancel;	459	$self->{_status} = [@_];
		460	Coro::State::cancel $self;
439	}	461	}
440	}	462	}
441		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
442	=item $coroutine->join	506	=item $coro->join
443		507
444	Wait until the coroutine terminates and return any values given to the	508	Wait until the coro terminates and return any values given to the
445	C<terminate> or C<cancel> functions. C<join> can be called concurrently	509	C<terminate> or C<cancel> functions. C<join> can be called concurrently
446	from multiple coroutines, and all will be resumed and given the status	510	from multiple coro, and all will be resumed and given the status
447	return once the C<$coroutine> terminates.	511	return once the C<$coro> terminates.
448		512
449	=cut	513	=cut
450		514
451	sub join {	515	sub join {
452	my $self = shift;	516	my $self = shift;
…		…
463	}	527	}
464		528
465	wantarray ? @{$self->{_status}} : $self->{_status}[0];	529	wantarray ? @{$self->{_status}} : $self->{_status}[0];
466	}	530	}
467		531
468	=item $coroutine->on_destroy (\&cb)	532	=item $coro->on_destroy (\&cb)
469		533
470	Registers a callback that is called when this coroutine gets destroyed,	534	Registers a callback that is called when this coro gets destroyed,
471	but before it is joined. The callback gets passed the terminate arguments,	535	but before it is joined. The callback gets passed the terminate arguments,
472	if any, and I<must not> die, under any circumstances.	536	if any, and I<must not> die, under any circumstances.
473		537
474	=cut	538	=cut
475		539
…		…
477	my ($self, $cb) = @_;	541	my ($self, $cb) = @_;
478		542
479	push @{ $self->{_on_destroy} }, $cb;	543	push @{ $self->{_on_destroy} }, $cb;
480	}	544	}
481		545
482	=item $oldprio = $coroutine->prio ($newprio)	546	=item $oldprio = $coro->prio ($newprio)
483		547
484	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
485	coroutine. Higher priority coroutines get run before lower priority	549	coro. Higher priority coro get run before lower priority
486	coroutines. Priorities are small signed integers (currently -4 .. +3),	550	coro. Priorities are small signed integers (currently -4 .. +3),
487	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
488	to get then):	552	to get then):
489		553
490	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
491	3 > 1 > 0 > -1 > -3 > -4	555	3 > 1 > 0 > -1 > -3 > -4
492		556
493	# set priority to HIGH	557	# set priority to HIGH
494	current->prio(PRIO_HIGH);	558	current->prio (PRIO_HIGH);
495		559
496	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
497	existing coroutine.	561	existing coro.
498		562
499	Changing the priority of the current coroutine will take effect immediately,	563	Changing the priority of the current coro will take effect immediately,
500	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
501	running) will only take effect after the next schedule (of that	565	running) will only take effect after the next schedule (of that
502	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.
503		567
504	=item $newprio = $coroutine->nice ($change)	568	=item $newprio = $coro->nice ($change)
505		569
506	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.
507	higher values mean lower priority, just as in unix).	571	higher values mean lower priority, just as in unix).
508		572
509	=item $olddesc = $coroutine->desc ($newdesc)	573	=item $olddesc = $coro->desc ($newdesc)
510		574
511	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
512	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.
513		578
514	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
515	can modify this member directly if you wish.	580	string. You can modify this member directly if you wish.
516
517	=item $coroutine->throw ([$scalar])
518
519	If C<$throw> is specified and defined, it will be thrown as an exception
520	inside the coroutine at the next convinient point in time (usually after
521	it gains control at the next schedule/transfer/cede). Otherwise clears the
522	exception object.
523
524	The exception object will be thrown "as is" with the specified scalar in
525	C<$@>, i.e. if it is a string, no line number or newline will be appended
526	(unlike with C<die>).
527
528	This can be used as a softer means than C<cancel> to ask a coroutine to
529	end itself, although there is no guarentee that the exception will lead to
530	termination, and if the exception isn't caught it might well end the whole
531	program.
532		581
533	=cut	582	=cut
534		583
535	sub desc {	584	sub desc {
536	my $old = $_[0]{desc};	585	my $old = $_[0]{desc};
537	$_[0]{desc} = $_[1] if @_ > 1;	586	$_[0]{desc} = $_[1] if @_ > 1;
538	$old;	587	$old;
539	}	588	}
540		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
541	=back	595	=back
542		596
543	=head2 GLOBAL FUNCTIONS	597	=head1 GLOBAL FUNCTIONS
544		598
545	=over 4	599	=over 4
546		600
547	=item Coro::nready	601	=item Coro::nready
548		602
549	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,
550	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
551	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
552	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>
553	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
554	coroutines.	608	coro.
555		609
556	=item my $guard = Coro::guard { ... }	610	=item my $guard = Coro::guard { ... }
557		611
558	This creates and returns a guard object. Nothing happens until the object	612	This function still exists, but is deprecated. Please use the
559	gets destroyed, in which case the codeblock given as argument will be	613	C<Guard::guard> function instead.
560	executed. This is useful to free locks or other resources in case of a
561	runtime error or when the coroutine gets canceled, as in both cases the
562	guard block will be executed. The guard object supports only one method,
563	C<< ->cancel >>, which will keep the codeblock from being executed.
564		614
565	Example: set some flag and clear it again when the coroutine gets canceled
566	or the function returns:
567
568	sub do_something {
569	my $guard = Coro::guard { $busy = 0 };
570	$busy = 1;
571
572	# do something that requires $busy to be true
573	}
574
575	=cut	615	=cut
576		616
577	sub guard(&) {	617	BEGIN { *guard = \&Guard::guard }
578	bless \(my $cb = $_[0]), "Coro::guard"
579	}
580
581	sub Coro::guard::cancel {
582	${$_[0]} = sub { };
583	}
584
585	sub Coro::guard::DESTROY {
586	${$_[0]}->();
587	}
588
589		618
590	=item unblock_sub { ... }	619	=item unblock_sub { ... }
591		620
592	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,
593	returning a new coderef. Unblocking means that calling the new coderef	622	returning a new coderef. Unblocking means that calling the new coderef
594	will return immediately without blocking, returning nothing, while the	623	will return immediately without blocking, returning nothing, while the
595	original code ref will be called (with parameters) from within another	624	original code ref will be called (with parameters) from within another
596	coroutine.	625	coro.
597		626
598	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
599	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
600	of thread-safety). This means you must not block within event callbacks,	629	of reentrancy). This means you must not block within event callbacks,
601	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
602	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>.
603		632
604	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
605	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
606	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
607	disk, for example.	636	disk, for example.
608		637
609	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
610	creating event callbacks that want to block.	639	creating event callbacks that want to block.
611		640
612	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
613	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
614	there is no reason to use C<unblock_sub>.	643	no reason to use C<unblock_sub>.
		644
		645	Note that you also need to use C<unblock_sub> for any other callbacks that
		646	are indirectly executed by any C-based event loop. For example, when you
		647	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		648	provides callbacks that are the result of some event callback, then you
		649	must not block either, or use C<unblock_sub>.
615		650
616	=cut	651	=cut
617		652
618	our @unblock_queue;	653	our @unblock_queue;
619		654
…		…
622	# return immediately and can be reused) and because we cannot cede	657	# return immediately and can be reused) and because we cannot cede
623	# inside an event callback.	658	# inside an event callback.
624	our $unblock_scheduler = new Coro sub {	659	our $unblock_scheduler = new Coro sub {
625	while () {	660	while () {
626	while (my $cb = pop @unblock_queue) {	661	while (my $cb = pop @unblock_queue) {
627	# this is an inlined copy of async_pool	662	&async_pool (@$cb);
628	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
629		663
630	$coro->{_invoke} = $cb;
631	$coro->ready;
632	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;
633	}	668	}
634	schedule; # sleep well	669	schedule; # sleep well
635	}	670	}
636	};	671	};
637	$unblock_scheduler->desc ("[unblock_sub scheduler]");	672	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
638		673
639	sub unblock_sub(&) {	674	sub unblock_sub(&) {
640	my $cb = shift;	675	my $cb = shift;
641		676
642	sub {	677	sub {
643	unshift @unblock_queue, [$cb, @_];	678	unshift @unblock_queue, [$cb, @_];
644	$unblock_scheduler->ready;	679	$unblock_scheduler->ready;
645	}	680	}
646	}	681	}
647		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
648	=back	702	=back
649		703
650	=cut	704	=cut
651		705
652	1;	706	1;
653		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
654	=head1 BUGS/LIMITATIONS	774	=head1 BUGS/LIMITATIONS
655		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
656	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
657	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
658	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
659	this). I recommend disabling thread support and using processes, as this	790	this). I recommend disabling thread support and using processes, as having
660	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
661		806
662	=head1 SEE ALSO	807	=head1 SEE ALSO
663		808
664	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>.
665		810
666	Debugging: L<Coro::Debug>.	811	Debugging: L<Coro::Debug>.
667		812
668	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	813	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
669		814
670	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>.
671		817
672	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>.
673		819
674	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>.
675		823
676	XS API: L<Coro::MakeMaker>.	824	XS API: L<Coro::MakeMaker>.
677		825
678	Low level Configuration, Coroutine Environment: L<Coro::State>.	826	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
679		827
680	=head1 AUTHOR	828	=head1 AUTHOR
681		829
682	Marc Lehmann <schmorp@schmorp.de>	830	Marc Lehmann <schmorp@schmorp.de>
683	http://home.schmorp.de/	831	http://home.schmorp.de/

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.181 by root, Fri May 9 22:04:37 2008 UTC vs. Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.181 by root, Fri May 9 22:04:37 2008 UTC vs.
Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC