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

Comparing Coro/Coro.pm (file contents):
Revision 1.140 by root, Thu Sep 27 16:25:10 2007 UTC vs.
Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only real threads in perl
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coro
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	For a tutorial-style introduction, please read the L<Coro::Intro>
24	to threads but don't run in parallel at the same time even on SMP	32	manpage. This manpage mainly contains reference information.
25	machines. The specific flavor of coroutine used in this module also
26	guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.
30		33
31	(Perl, however, does not natively support real threads but instead does a	34	This module collection manages continuations in general, most often in
32	very slow and memory-intensive emulation of processes using threads. This	35	the form of cooperative threads (also called coros, or simply "coro"
33	is a performance win on Windows machines, and a loss everywhere else).	36	in the documentation). They are similar to kernel threads but don't (in
		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.
34		43
		44	Unlike the so-called "Perl threads" (which are not actually real threads
		45	but only the windows process emulation (see section of same name for more
		46	details) ported to unix, and as such act as processes), Coro provides
		47	a full shared address space, which makes communication between threads
		48	very easy. And Coro's threads are fast, too: disabling the Windows
		49	process emulation code in your perl and using Coro can easily result in
		50	a two to four times speed increase for your programs. A parallel matrix
		51	multiplication benchmark runs over 300 times faster on a single core than
		52	perl's pseudo-threads on a quad core using all four cores.
		53
		54	Coro achieves that by supporting multiple running interpreters that share
		55	data, which is especially useful to code pseudo-parallel processes and
		56	for event-based programming, such as multiple HTTP-GET requests running
		57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		58	into an event-based environment.
		59
35	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
37	its own set of lexicals and its own set of perls most important global	62	its own set of lexicals and its own set of perls most important global
38	variables.	63	variables (see L<Coro::State> for more configuration and background info).
		64
		65	See also the C<SEE ALSO> section at the end of this document - the Coro
		66	module family is quite large.
39		67
40	=cut	68	=cut
41		69
42	package Coro;	70	package Coro;
43		71
44	use strict;	72	use common::sense;
45	no warnings "uninitialized";	73
		74	use Carp ();
		75
		76	use Guard ();
46		77
47	use Coro::State;	78	use Coro::State;
48		79
49	use base qw(Coro::State Exporter);	80	use base qw(Coro::State Exporter);
50		81
51	our $idle; # idle handler	82	our $idle; # idle handler
52	our $main; # main coroutine	83	our $main; # main coro
53	our $current; # current coroutine	84	our $current; # current coro
54		85
55	our $VERSION = '3.8';	86	our $VERSION = 5.17;
56		87
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	89	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	91	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	92	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		93
63	{	94	=head1 GLOBAL VARIABLES
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96		95
97	=over 4	96	=over 4
98		97
99	=item $main	98	=item $Coro::main
100		99
101	This coroutine represents the main program.	100	This variable stores the Coro object that represents the main
		101	program. While you cna C<ready> it and do most other things you can do to
		102	coro, it is mainly useful to compare again C<$Coro::current>, to see
		103	whether you are running in the main program or not.
102		104
103	=cut	105	=cut
104		106
105	$main = new Coro;	107	# $main is now being initialised by Coro::State
106		108
107	=item $current (or as function: current)	109	=item $Coro::current
108		110
109	The current coroutine (the last coroutine switched to). The initial value	111	The Coro object representing the current coro (the last
		112	coro that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	113	C<$Coro::main> (of course).
111		114
112	This variable is B<strictly> I<read-only>. It is provided for performance	115	This variable is B<strictly> I<read-only>. You can take copies of the
113	reasons. If performance is not essential you are encouraged to use the	116	value stored in it and use it as any other Coro object, but you must
114	C<Coro::current> function instead.	117	not otherwise modify the variable itself.
115		118
116	=cut	119	=cut
117		120
118	$main->{desc} = "[main::]";
119
120	# maybe some other module used Coro::Specific before...
121	$main->{specific} = $current->{specific}
122	if $current;
123
124	_set_current $main;
125
126	sub current() { $current }	121	sub current() { $current } # [DEPRECATED]
127		122
128	=item $idle	123	=item $Coro::idle
129		124
		125	This variable is mainly useful to integrate Coro into event loops. It is
		126	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		127	pretty low-level functionality.
		128
		129	This variable stores either a Coro object or a callback.
		130
130	A callback that is called whenever the scheduler finds no ready coroutines	131	If it is a callback, the it is called whenever the scheduler finds no
131	to run. The default implementation prints "FATAL: deadlock detected" and	132	ready coros to run. The default implementation prints "FATAL:
132	exits, because the program has no other way to continue.	133	deadlock detected" and exits, because the program has no other way to
		134	continue.
133		135
		136	If it is a coro object, then this object will be readied (without
		137	invoking any ready hooks, however) when the scheduler finds no other ready
		138	coros to run.
		139
134	This hook is overwritten by modules such as C<Coro::Timer> and	140	This hook is overwritten by modules such as C<Coro::EV> and
135	C<Coro::Event> to wait on an external event that hopefully wake up a	141	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
136	coroutine so the scheduler can run it.	142	coro so the scheduler can run it.
		143
		144	Note that the callback I<must not>, under any circumstances, block
		145	the current coro. Normally, this is achieved by having an "idle
		146	coro" that calls the event loop and then blocks again, and then
		147	readying that coro in the idle handler, or by simply placing the idle
		148	coro in this variable.
		149
		150	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		151	technique.
137		152
138	Please note that if your callback recursively invokes perl (e.g. for event	153	Please note that if your callback recursively invokes perl (e.g. for event
139	handlers), then it must be prepared to be called recursively.	154	handlers), then it must be prepared to be called recursively itself.
140		155
141	=cut	156	=cut
142		157
143	$idle = sub {	158	$idle = sub {
144	require Carp;	159	warn "oi\n";#d#
145	Carp::croak ("FATAL: deadlock detected");	160	Carp::confess ("FATAL: deadlock detected");
146	};	161	};
147		162
148	sub _cancel {
149	my ($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->{destroy_cb}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	163	# this coro is necessary because a coro
161	# cannot destroy itself.	164	# cannot destroy itself.
162	my @destroy;	165	our @destroy;
163	my $manager;	166	our $manager;
164		167
165	$manager = new Coro sub {	168	$manager = new Coro sub {
166	while () {	169	while () {
167	(shift @destroy)->_cancel	170	Coro::State::cancel shift @destroy
168	while @destroy;	171	while @destroy;
169		172
170	&schedule;	173	&schedule;
171	}	174	}
172	};	175	};
173	$manager->desc ("[coro manager]");	176	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	177	$manager->prio (PRIO_MAX);
175		178
176	# static methods. not really.
177
178	=back	179	=back
179		180
180	=head2 STATIC METHODS	181	=head1 SIMPLE CORO CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		182
184	=over 4	183	=over 4
185		184
186	=item async { ... } [@args...]	185	=item async { ... } [@args...]
187		186
188	Create a new asynchronous coroutine and return it's coroutine object	187	Create a new coro and return its Coro object (usually
189	(usually unused). When the sub returns the new coroutine is automatically	188	unused). The coro will be put into the ready queue, so
		189	it will start running automatically on the next scheduler run.
		190
		191	The first argument is a codeblock/closure that should be executed in the
		192	coro. When it returns argument returns the coro is automatically
190	terminated.	193	terminated.
191		194
		195	The remaining arguments are passed as arguments to the closure.
		196
		197	See the C<Coro::State::new> constructor for info about the coro
		198	environment in which coro are executed.
		199
192	Calling C<exit> in a coroutine will do the same as calling exit outside	200	Calling C<exit> in a coro will do the same as calling exit outside
193	the coroutine. Likewise, when the coroutine dies, the program will exit,	201	the coro. Likewise, when the coro dies, the program will exit,
194	just as it would in the main program.	202	just as it would in the main program.
195		203
		204	If you do not want that, you can provide a default C<die> handler, or
		205	simply avoid dieing (by use of C<eval>).
		206
196	# create a new coroutine that just prints its arguments	207	Example: Create a new coro that just prints its arguments.
		208
197	async {	209	async {
198	print "@_\n";	210	print "@_\n";
199	} 1,2,3,4;	211	} 1,2,3,4;
200		212
201	=cut
202
203	sub async(&@) {
204	my $coro = new Coro @_;
205	$coro->ready;
206	$coro
207	}
208
209	=item async_pool { ... } [@args...]	213	=item async_pool { ... } [@args...]
210		214
211	Similar to C<async>, but uses a coroutine pool, so you should not call	215	Similar to C<async>, but uses a coro pool, so you should not call
212	terminate or join (although you are allowed to), and you get a coroutine	216	terminate or join on it (although you are allowed to), and you get a
213	that might have executed other code already (which can be good or bad :).	217	coro that might have executed other code already (which can be good
		218	or bad :).
214		219
		220	On the plus side, this function is about twice as fast as creating (and
		221	destroying) a completely new coro, so if you need a lot of generic
		222	coros in quick successsion, use C<async_pool>, not C<async>.
		223
215	Also, the block is executed in an C<eval> context and a warning will be	224	The code block is executed in an C<eval> context and a warning will be
216	issued in case of an exception instead of terminating the program, as	225	issued in case of an exception instead of terminating the program, as
217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	226	C<async> does. As the coro is being reused, stuff like C<on_destroy>
218	will not work in the expected way, unless you call terminate or cancel,	227	will not work in the expected way, unless you call terminate or cancel,
219	which somehow defeats the purpose of pooling.	228	which somehow defeats the purpose of pooling (but is fine in the
		229	exceptional case).
220		230
221	The priority will be reset to C<0> after each job, otherwise the coroutine	231	The priority will be reset to C<0> after each run, tracing will be
222	will be re-used "as-is".	232	disabled, the description will be reset and the default output filehandle
		233	gets restored, so you can change all these. Otherwise the coro will
		234	be re-used "as-is": most notably if you change other per-coro global
		235	stuff such as C<$/> you I<must needs> revert that change, which is most
		236	simply done by using local as in: C<< local $/ >>.
223		237
224	The pool size is limited to 8 idle coroutines (this can be adjusted by	238	The idle pool size is limited to C<8> idle coros (this can be
225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	239	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
226	required.	240	coros as required.
227		241
228	If you are concerned about pooled coroutines growing a lot because a	242	If you are concerned about pooled coros growing a lot because a
229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	243	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
230	{ terminate }> once per second or so to slowly replenish the pool. In	244	{ terminate }> once per second or so to slowly replenish the pool. In
231	addition to that, when the stacks used by a handler grows larger than 16kb	245	addition to that, when the stacks used by a handler grows larger than 32kb
232	(adjustable with $Coro::POOL_RSS) it will also exit.	246	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
233		247
234	=cut	248	=cut
235		249
236	our $POOL_SIZE = 8;	250	our $POOL_SIZE = 8;
237	our $POOL_RSS = 16 * 1024;	251	our $POOL_RSS = 32 * 1024;
238	our @async_pool;	252	our @async_pool;
239		253
240	sub pool_handler {	254	sub pool_handler {
241	my $cb;
242
243	while () {	255	while () {
244	eval {	256	eval {
245	while () {	257	&{&_pool_handler} while 1;
246	_pool_1 $cb;
247	&$cb;
248	_pool_2 $cb;
249	&schedule;
250	}
251	};	258	};
252		259
253	last if $@ eq "\3terminate\2\n";
254	warn $@ if $@;	260	warn $@ if $@;
255	}	261	}
256	}	262	}
257		263
258	sub async_pool(&@) {	264	=back
259	# this is also inlined into the unlock_scheduler
260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
261		265
262	$coro->{_invoke} = [@_];	266	=head1 STATIC METHODS
263	$coro->ready;
264		267
265	$coro	268	Static methods are actually functions that implicitly operate on the
		269	current coro.
		270
		271	=over 4
		272
		273	=item schedule
		274
		275	Calls the scheduler. The scheduler will find the next coro that is
		276	to be run from the ready queue and switches to it. The next coro
		277	to be run is simply the one with the highest priority that is longest
		278	in its ready queue. If there is no coro ready, it will clal the
		279	C<$Coro::idle> hook.
		280
		281	Please note that the current coro will I<not> be put into the ready
		282	queue, so calling this function usually means you will never be called
		283	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		284	thus waking you up.
		285
		286	This makes C<schedule> I<the> generic method to use to block the current
		287	coro and wait for events: first you remember the current coro in
		288	a variable, then arrange for some callback of yours to call C<< ->ready
		289	>> on that once some event happens, and last you call C<schedule> to put
		290	yourself to sleep. Note that a lot of things can wake your coro up,
		291	so you need to check whether the event indeed happened, e.g. by storing the
		292	status in a variable.
		293
		294	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		295
		296	=item cede
		297
		298	"Cede" to other coros. This function puts the current coro into
		299	the ready queue and calls C<schedule>, which has the effect of giving
		300	up the current "timeslice" to other coros of the same or higher
		301	priority. Once your coro gets its turn again it will automatically be
		302	resumed.
		303
		304	This function is often called C<yield> in other languages.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to I<any>
		309	coro, regardless of priority. This is useful sometimes to ensure
		310	progress is made.
		311
		312	=item terminate [arg...]
		313
		314	Terminates the current coro with the given status values (see L<cancel>).
		315
		316	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		317
		318	These function install enter and leave winders in the current scope. The
		319	enter block will be executed when on_enter is called and whenever the
		320	current coro is re-entered by the scheduler, while the leave block is
		321	executed whenever the current coro is blocked by the scheduler, and
		322	also when the containing scope is exited (by whatever means, be it exit,
		323	die, last etc.).
		324
		325	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		326	BLOCKs>. That means: do not even think about calling C<die> without an
		327	eval, and do not even think of entering the scheduler in any way.
		328
		329	Since both BLOCKs are tied to the current scope, they will automatically
		330	be removed when the current scope exits.
		331
		332	These functions implement the same concept as C<dynamic-wind> in scheme
		333	does, and are useful when you want to localise some resource to a specific
		334	coro.
		335
		336	They slow down thread switching considerably for coros that use them
		337	(about 40% for a BLOCK with a single assignment, so thread switching is
		338	still reasonably fast if the handlers are fast).
		339
		340	These functions are best understood by an example: The following function
		341	will change the current timezone to "Antarctica/South_Pole", which
		342	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		343	which remember/change the current timezone and restore the previous
		344	value, respectively, the timezone is only changed for the coro that
		345	installed those handlers.
		346
		347	use POSIX qw(tzset);
		348
		349	async {
		350	my $old_tz; # store outside TZ value here
		351
		352	Coro::on_enter {
		353	$old_tz = $ENV{TZ}; # remember the old value
		354
		355	$ENV{TZ} = "Antarctica/South_Pole";
		356	tzset; # enable new value
		357	};
		358
		359	Coro::on_leave {
		360	$ENV{TZ} = $old_tz;
		361	tzset; # restore old value
		362	};
		363
		364	# at this place, the timezone is Antarctica/South_Pole,
		365	# without disturbing the TZ of any other coro.
		366	};
		367
		368	This can be used to localise about any resource (locale, uid, current
		369	working directory etc.) to a block, despite the existance of other
		370	coros.
		371
		372	Another interesting example implements time-sliced multitasking using
		373	interval timers (this could obviously be optimised, but does the job):
		374
		375	# "timeslice" the given block
		376	sub timeslice(&) {
		377	use Time::HiRes ();
		378
		379	Coro::on_enter {
		380	# on entering the thread, we set an VTALRM handler to cede
		381	$SIG{VTALRM} = sub { cede };
		382	# and then start the interval timer
		383	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		384	};
		385	Coro::on_leave {
		386	# on leaving the thread, we stop the interval timer again
		387	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		388	};
		389
		390	&{+shift};
		391	}
		392
		393	# use like this:
		394	timeslice {
		395	# The following is an endless loop that would normally
		396	# monopolise the process. Since it runs in a timesliced
		397	# environment, it will regularly cede to other threads.
		398	while () { }
		399	};
		400
		401
		402	=item killall
		403
		404	Kills/terminates/cancels all coros except the currently running one.
		405
		406	Note that while this will try to free some of the main interpreter
		407	resources if the calling coro isn't the main coro, but one
		408	cannot free all of them, so if a coro that is not the main coro
		409	calls this function, there will be some one-time resource leak.
		410
		411	=cut
		412
		413	sub killall {
		414	for (Coro::State::list) {
		415	$_->cancel
		416	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		417	}
266	}	418	}
267		419
268	=item schedule	420	=back
269		421
270	Calls the scheduler. Please note that the current coroutine will not be put	422	=head1 CORO OBJECT METHODS
271	into the ready queue, so calling this function usually means you will
272	never be called again unless something else (e.g. an event handler) calls
273	ready.
274		423
275	The canonical way to wait on external events is this:	424	These are the methods you can call on coro objects (or to create
		425	them).
276		426
		427	=over 4
		428
		429	=item new Coro \&sub [, @args...]
		430
		431	Create a new coro and return it. When the sub returns, the coro
		432	automatically terminates as if C<terminate> with the returned values were
		433	called. To make the coro run you must first put it into the ready
		434	queue by calling the ready method.
		435
		436	See C<async> and C<Coro::State::new> for additional info about the
		437	coro environment.
		438
		439	=cut
		440
		441	sub _coro_run {
		442	terminate &{+shift};
		443	}
		444
		445	=item $success = $coro->ready
		446
		447	Put the given coro into the end of its ready queue (there is one
		448	queue for each priority) and return true. If the coro is already in
		449	the ready queue, do nothing and return false.
		450
		451	This ensures that the scheduler will resume this coro automatically
		452	once all the coro of higher priority and all coro of the same
		453	priority that were put into the ready queue earlier have been resumed.
		454
		455	=item $coro->suspend
		456
		457	Suspends the specified coro. A suspended coro works just like any other
		458	coro, except that the scheduler will not select a suspended coro for
		459	execution.
		460
		461	Suspending a coro can be useful when you want to keep the coro from
		462	running, but you don't want to destroy it, or when you want to temporarily
		463	freeze a coro (e.g. for debugging) to resume it later.
		464
		465	A scenario for the former would be to suspend all (other) coros after a
		466	fork and keep them alive, so their destructors aren't called, but new
		467	coros can be created.
		468
		469	=item $coro->resume
		470
		471	If the specified coro was suspended, it will be resumed. Note that when
		472	the coro was in the ready queue when it was suspended, it might have been
		473	unreadied by the scheduler, so an activation might have been lost.
		474
		475	To avoid this, it is best to put a suspended coro into the ready queue
		476	unconditionally, as every synchronisation mechanism must protect itself
		477	against spurious wakeups, and the one in the Coro family certainly do
		478	that.
		479
		480	=item $is_ready = $coro->is_ready
		481
		482	Returns true iff the Coro object is in the ready queue. Unless the Coro
		483	object gets destroyed, it will eventually be scheduled by the scheduler.
		484
		485	=item $is_running = $coro->is_running
		486
		487	Returns true iff the Coro object is currently running. Only one Coro object
		488	can ever be in the running state (but it currently is possible to have
		489	multiple running Coro::States).
		490
		491	=item $is_suspended = $coro->is_suspended
		492
		493	Returns true iff this Coro object has been suspended. Suspended Coros will
		494	not ever be scheduled.
		495
		496	=item $coro->cancel (arg...)
		497
		498	Terminates the given Coro and makes it return the given arguments as
		499	status (default: the empty list). Never returns if the Coro is the
		500	current Coro.
		501
		502	=cut
		503
		504	sub cancel {
		505	my $self = shift;
		506
		507	if ($current == $self) {
		508	terminate @_;
		509	} else {
		510	$self->{_status} = [@_];
		511	Coro::State::cancel $self;
277	{	512	}
278	# remember current coroutine	513	}
		514
		515	=item $coro->schedule_to
		516
		517	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		518	of continuing with the next coro from the ready queue, always switch to
		519	the given coro object (regardless of priority etc.). The readyness
		520	state of that coro isn't changed.
		521
		522	This is an advanced method for special cases - I'd love to hear about any
		523	uses for this one.
		524
		525	=item $coro->cede_to
		526
		527	Like C<schedule_to>, but puts the current coro into the ready
		528	queue. This has the effect of temporarily switching to the given
		529	coro, and continuing some time later.
		530
		531	This is an advanced method for special cases - I'd love to hear about any
		532	uses for this one.
		533
		534	=item $coro->throw ([$scalar])
		535
		536	If C<$throw> is specified and defined, it will be thrown as an exception
		537	inside the coro at the next convenient point in time. Otherwise
		538	clears the exception object.
		539
		540	Coro will check for the exception each time a schedule-like-function
		541	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		542	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		543	detect this case and return early in case an exception is pending.
		544
		545	The exception object will be thrown "as is" with the specified scalar in
		546	C<$@>, i.e. if it is a string, no line number or newline will be appended
		547	(unlike with C<die>).
		548
		549	This can be used as a softer means than C<cancel> to ask a coro to
		550	end itself, although there is no guarantee that the exception will lead to
		551	termination, and if the exception isn't caught it might well end the whole
		552	program.
		553
		554	You might also think of C<throw> as being the moral equivalent of
		555	C<kill>ing a coro with a signal (in this case, a scalar).
		556
		557	=item $coro->join
		558
		559	Wait until the coro terminates and return any values given to the
		560	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		561	from multiple coro, and all will be resumed and given the status
		562	return once the C<$coro> terminates.
		563
		564	=cut
		565
		566	sub join {
		567	my $self = shift;
		568
		569	unless ($self->{_status}) {
279	my $current = $Coro::current;	570	my $current = $current;
280		571
281	# register a hypothetical event handler	572	push @{$self->{_on_destroy}}, sub {
282	on_event_invoke sub {
283	# wake up sleeping coroutine
284	$current->ready;	573	$current->ready;
285	undef $current;	574	undef $current;
286	};	575	};
287		576
288	# call schedule until event occurred.
289	# in case we are woken up for other reasons
290	# (current still defined), loop.
291	Coro::schedule while $current;
292	}
293
294	=item cede
295
296	"Cede" to other coroutines. This function puts the current coroutine into the
297	ready queue and calls C<schedule>, which has the effect of giving up the
298	current "timeslice" to other coroutines of the same or higher priority.
299
300	Returns true if at least one coroutine switch has happened.
301
302	=item Coro::cede_notself
303
304	Works like cede, but is not exported by default and will cede to any
305	coroutine, regardless of priority, once.
306
307	Returns true if at least one coroutine switch has happened.
308
309	=item terminate [arg...]
310
311	Terminates the current coroutine with the given status values (see L<cancel>).
312
313	=cut
314
315	sub terminate {
316	$current->cancel (@_);
317	}
318
319	=back
320
321	# dynamic methods
322
323	=head2 COROUTINE METHODS
324
325	These are the methods you can call on coroutine objects.
326
327	=over 4
328
329	=item new Coro \&sub [, @args...]
330
331	Create a new coroutine and return it. When the sub returns the coroutine
332	automatically terminates as if C<terminate> with the returned values were
333	called. To make the coroutine run you must first put it into the ready queue
334	by calling the ready method.
335
336	See C<async> for additional discussion.
337
338	=cut
339
340	sub _run_coro {
341	terminate &{+shift};
342	}
343
344	sub new {
345	my $class = shift;
346
347	$class->SUPER::new (\&_run_coro, @_)
348	}
349
350	=item $success = $coroutine->ready
351
352	Put the given coroutine into the ready queue (according to it's priority)
353	and return true. If the coroutine is already in the ready queue, do nothing
354	and return false.
355
356	=item $is_ready = $coroutine->is_ready
357
358	Return wether the coroutine is currently the ready queue or not,
359
360	=item $coroutine->cancel (arg...)
361
362	Terminates the given coroutine and makes it return the given arguments as
363	status (default: the empty list). Never returns if the coroutine is the
364	current coroutine.
365
366	=cut
367
368	sub cancel {
369	my $self = shift;
370	$self->{status} = [@_];
371
372	if ($current == $self) {
373	push @destroy, $self;
374	$manager->ready;
375	&schedule while 1;
376	} else {
377	$self->_cancel;
378	}
379	}
380
381	=item $coroutine->join
382
383	Wait until the coroutine terminates and return any values given to the
384	C<terminate> or C<cancel> functions. C<join> can be called multiple times
385	from multiple coroutine.
386
387	=cut
388
389	sub join {
390	my $self = shift;
391
392	unless ($self->{status}) {
393	my $current = $current;
394
395	push @{$self->{destroy_cb}}, sub {
396	$current->ready;
397	undef $current;
398	};
399
400	&schedule while $current;	577	&schedule while $current;
401	}	578	}
402		579
403	wantarray ? @{$self->{status}} : $self->{status}[0];	580	wantarray ? @{$self->{_status}} : $self->{_status}[0];
404	}	581	}
405		582
406	=item $coroutine->on_destroy (\&cb)	583	=item $coro->on_destroy (\&cb)
407		584
408	Registers a callback that is called when this coroutine gets destroyed,	585	Registers a callback that is called when this coro gets destroyed,
409	but before it is joined. The callback gets passed the terminate arguments,	586	but before it is joined. The callback gets passed the terminate arguments,
410	if any.	587	if any, and I<must not> die, under any circumstances.
411		588
412	=cut	589	=cut
413		590
414	sub on_destroy {	591	sub on_destroy {
415	my ($self, $cb) = @_;	592	my ($self, $cb) = @_;
416		593
417	push @{ $self->{destroy_cb} }, $cb;	594	push @{ $self->{_on_destroy} }, $cb;
418	}	595	}
419		596
420	=item $oldprio = $coroutine->prio ($newprio)	597	=item $oldprio = $coro->prio ($newprio)
421		598
422	Sets (or gets, if the argument is missing) the priority of the	599	Sets (or gets, if the argument is missing) the priority of the
423	coroutine. Higher priority coroutines get run before lower priority	600	coro. Higher priority coro get run before lower priority
424	coroutines. Priorities are small signed integers (currently -4 .. +3),	601	coro. Priorities are small signed integers (currently -4 .. +3),
425	that you can refer to using PRIO_xxx constants (use the import tag :prio	602	that you can refer to using PRIO_xxx constants (use the import tag :prio
426	to get then):	603	to get then):
427		604
428	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	605	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
429	3 > 1 > 0 > -1 > -3 > -4	606	3 > 1 > 0 > -1 > -3 > -4
430		607
431	# set priority to HIGH	608	# set priority to HIGH
432	current->prio(PRIO_HIGH);	609	current->prio (PRIO_HIGH);
433		610
434	The idle coroutine ($Coro::idle) always has a lower priority than any	611	The idle coro ($Coro::idle) always has a lower priority than any
435	existing coroutine.	612	existing coro.
436		613
437	Changing the priority of the current coroutine will take effect immediately,	614	Changing the priority of the current coro will take effect immediately,
438	but changing the priority of coroutines in the ready queue (but not	615	but changing the priority of coro in the ready queue (but not
439	running) will only take effect after the next schedule (of that	616	running) will only take effect after the next schedule (of that
440	coroutine). This is a bug that will be fixed in some future version.	617	coro). This is a bug that will be fixed in some future version.
441		618
442	=item $newprio = $coroutine->nice ($change)	619	=item $newprio = $coro->nice ($change)
443		620
444	Similar to C<prio>, but subtract the given value from the priority (i.e.	621	Similar to C<prio>, but subtract the given value from the priority (i.e.
445	higher values mean lower priority, just as in unix).	622	higher values mean lower priority, just as in unix).
446		623
447	=item $olddesc = $coroutine->desc ($newdesc)	624	=item $olddesc = $coro->desc ($newdesc)
448		625
449	Sets (or gets in case the argument is missing) the description for this	626	Sets (or gets in case the argument is missing) the description for this
450	coroutine. This is just a free-form string you can associate with a coroutine.	627	coro. This is just a free-form string you can associate with a
		628	coro.
		629
		630	This method simply sets the C<< $coro->{desc} >> member to the given
		631	string. You can modify this member directly if you wish.
451		632
452	=cut	633	=cut
453		634
454	sub desc {	635	sub desc {
455	my $old = $_[0]{desc};	636	my $old = $_[0]{desc};
456	$_[0]{desc} = $_[1] if @_ > 1;	637	$_[0]{desc} = $_[1] if @_ > 1;
457	$old;	638	$old;
458	}	639	}
459		640
		641	sub transfer {
		642	require Carp;
		643	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		644	}
		645
460	=back	646	=back
461		647
462	=head2 GLOBAL FUNCTIONS	648	=head1 GLOBAL FUNCTIONS
463		649
464	=over 4	650	=over 4
465		651
466	=item Coro::nready	652	=item Coro::nready
467		653
468	Returns the number of coroutines that are currently in the ready state,	654	Returns the number of coro that are currently in the ready state,
469	i.e. that can be switched to. The value C<0> means that the only runnable	655	i.e. that can be switched to by calling C<schedule> directory or
		656	indirectly. The value C<0> means that the only runnable coro is the
470	coroutine is the currently running one, so C<cede> would have no effect,	657	currently running one, so C<cede> would have no effect, and C<schedule>
471	and C<schedule> would cause a deadlock unless there is an idle handler	658	would cause a deadlock unless there is an idle handler that wakes up some
472	that wakes up some coroutines.	659	coro.
473		660
474	=item my $guard = Coro::guard { ... }	661	=item my $guard = Coro::guard { ... }
475		662
476	This creates and returns a guard object. Nothing happens until the object	663	This function still exists, but is deprecated. Please use the
477	gets destroyed, in which case the codeblock given as argument will be	664	C<Guard::guard> function instead.
478	executed. This is useful to free locks or other resources in case of a
479	runtime error or when the coroutine gets canceled, as in both cases the
480	guard block will be executed. The guard object supports only one method,
481	C<< ->cancel >>, which will keep the codeblock from being executed.
482		665
483	Example: set some flag and clear it again when the coroutine gets canceled
484	or the function returns:
485
486	sub do_something {
487	my $guard = Coro::guard { $busy = 0 };
488	$busy = 1;
489
490	# do something that requires $busy to be true
491	}
492
493	=cut	666	=cut
494		667
495	sub guard(&) {	668	BEGIN { *guard = \&Guard::guard }
496	bless \(my $cb = $_[0]), "Coro::guard"
497	}
498
499	sub Coro::guard::cancel {
500	${$_[0]} = sub { };
501	}
502
503	sub Coro::guard::DESTROY {
504	${$_[0]}->();
505	}
506
507		669
508	=item unblock_sub { ... }	670	=item unblock_sub { ... }
509		671
510	This utility function takes a BLOCK or code reference and "unblocks" it,	672	This utility function takes a BLOCK or code reference and "unblocks" it,
511	returning the new coderef. This means that the new coderef will return	673	returning a new coderef. Unblocking means that calling the new coderef
512	immediately without blocking, returning nothing, while the original code	674	will return immediately without blocking, returning nothing, while the
513	ref will be called (with parameters) from within its own coroutine.	675	original code ref will be called (with parameters) from within another
		676	coro.
514		677
515	The reason this function exists is that many event libraries (such as the	678	The reason this function exists is that many event libraries (such as the
516	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	679	venerable L<Event\|Event> module) are not thread-safe (a weaker form
517	of thread-safety). This means you must not block within event callbacks,	680	of reentrancy). This means you must not block within event callbacks,
518	otherwise you might suffer from crashes or worse.	681	otherwise you might suffer from crashes or worse. The only event library
		682	currently known that is safe to use without C<unblock_sub> is L<EV>.
519		683
520	This function allows your callbacks to block by executing them in another	684	This function allows your callbacks to block by executing them in another
521	coroutine where it is safe to block. One example where blocking is handy	685	coro where it is safe to block. One example where blocking is handy
522	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	686	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
523	disk.	687	disk, for example.
524		688
525	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	689	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
526	creating event callbacks that want to block.	690	creating event callbacks that want to block.
		691
		692	If your handler does not plan to block (e.g. simply sends a message to
		693	another coro, or puts some other coro into the ready queue), there is
		694	no reason to use C<unblock_sub>.
		695
		696	Note that you also need to use C<unblock_sub> for any other callbacks that
		697	are indirectly executed by any C-based event loop. For example, when you
		698	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		699	provides callbacks that are the result of some event callback, then you
		700	must not block either, or use C<unblock_sub>.
527		701
528	=cut	702	=cut
529		703
530	our @unblock_queue;	704	our @unblock_queue;
531		705
534	# return immediately and can be reused) and because we cannot cede	708	# return immediately and can be reused) and because we cannot cede
535	# inside an event callback.	709	# inside an event callback.
536	our $unblock_scheduler = new Coro sub {	710	our $unblock_scheduler = new Coro sub {
537	while () {	711	while () {
538	while (my $cb = pop @unblock_queue) {	712	while (my $cb = pop @unblock_queue) {
539	# this is an inlined copy of async_pool	713	&async_pool (@$cb);
540	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
541		714
542	$coro->{_invoke} = $cb;
543	$coro->ready;
544	cede; # for short-lived callbacks, this reduces pressure on the coro pool	715	# for short-lived callbacks, this reduces pressure on the coro pool
		716	# as the chance is very high that the async_poll coro will be back
		717	# in the idle state when cede returns
		718	cede;
545	}	719	}
546	schedule; # sleep well	720	schedule; # sleep well
547	}	721	}
548	};	722	};
549	$unblock_scheduler->desc ("[unblock_sub scheduler]");	723	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
550		724
551	sub unblock_sub(&) {	725	sub unblock_sub(&) {
552	my $cb = shift;	726	my $cb = shift;
553		727
554	sub {	728	sub {
555	unshift @unblock_queue, [$cb, @_];	729	unshift @unblock_queue, [$cb, @_];
556	$unblock_scheduler->ready;	730	$unblock_scheduler->ready;
557	}	731	}
558	}	732	}
559		733
		734	=item $cb = Coro::rouse_cb
		735
		736	Create and return a "rouse callback". That's a code reference that,
		737	when called, will remember a copy of its arguments and notify the owner
		738	coro of the callback.
		739
		740	See the next function.
		741
		742	=item @args = Coro::rouse_wait [$cb]
		743
		744	Wait for the specified rouse callback (or the last one that was created in
		745	this coro).
		746
		747	As soon as the callback is invoked (or when the callback was invoked
		748	before C<rouse_wait>), it will return the arguments originally passed to
		749	the rouse callback. In scalar context, that means you get the I<last>
		750	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		751	statement at the end.
		752
		753	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		754
560	=back	755	=back
561		756
562	=cut	757	=cut
563		758
564	1;	759	1;
565		760
		761	=head1 HOW TO WAIT FOR A CALLBACK
		762
		763	It is very common for a coro to wait for some callback to be
		764	called. This occurs naturally when you use coro in an otherwise
		765	event-based program, or when you use event-based libraries.
		766
		767	These typically register a callback for some event, and call that callback
		768	when the event occured. In a coro, however, you typically want to
		769	just wait for the event, simplyifying things.
		770
		771	For example C<< AnyEvent->child >> registers a callback to be called when
		772	a specific child has exited:
		773
		774	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		775
		776	But from within a coro, you often just want to write this:
		777
		778	my $status = wait_for_child $pid;
		779
		780	Coro offers two functions specifically designed to make this easy,
		781	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		782
		783	The first function, C<rouse_cb>, generates and returns a callback that,
		784	when invoked, will save its arguments and notify the coro that
		785	created the callback.
		786
		787	The second function, C<rouse_wait>, waits for the callback to be called
		788	(by calling C<schedule> to go to sleep) and returns the arguments
		789	originally passed to the callback.
		790
		791	Using these functions, it becomes easy to write the C<wait_for_child>
		792	function mentioned above:
		793
		794	sub wait_for_child($) {
		795	my ($pid) = @_;
		796
		797	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		798
		799	my ($rpid, $rstatus) = Coro::rouse_wait;
		800	$rstatus
		801	}
		802
		803	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		804	you can roll your own, using C<schedule>:
		805
		806	sub wait_for_child($) {
		807	my ($pid) = @_;
		808
		809	# store the current coro in $current,
		810	# and provide result variables for the closure passed to ->child
		811	my $current = $Coro::current;
		812	my ($done, $rstatus);
		813
		814	# pass a closure to ->child
		815	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		816	$rstatus = $_[1]; # remember rstatus
		817	$done = 1; # mark $rstatus as valud
		818	});
		819
		820	# wait until the closure has been called
		821	schedule while !$done;
		822
		823	$rstatus
		824	}
		825
		826
566	=head1 BUGS/LIMITATIONS	827	=head1 BUGS/LIMITATIONS
567		828
568	- you must make very sure that no coro is still active on global	829	=over 4
569	destruction. very bad things might happen otherwise (usually segfaults).
570		830
		831	=item fork with pthread backend
		832
		833	When Coro is compiled using the pthread backend (which isn't recommended
		834	but required on many BSDs as their libcs are completely broken), then
		835	coro will not survive a fork. There is no known workaround except to
		836	fix your libc and use a saner backend.
		837
		838	=item perl process emulation ("threads")
		839
571	- this module is not thread-safe. You should only ever use this module	840	This module is not perl-pseudo-thread-safe. You should only ever use this
572	from the same thread (this requirement might be loosened in the future	841	module from the first thread (this requirement might be removed in the
573	to allow per-thread schedulers, but Coro::State does not yet allow	842	future to allow per-thread schedulers, but Coro::State does not yet allow
574	this).	843	this). I recommend disabling thread support and using processes, as having
		844	the windows process emulation enabled under unix roughly halves perl
		845	performance, even when not used.
		846
		847	=item coro switching is not signal safe
		848
		849	You must not switch to another coro from within a signal handler
		850	(only relevant with %SIG - most event libraries provide safe signals).
		851
		852	That means you I<MUST NOT> call any function that might "block" the
		853	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		854	anything that calls those. Everything else, including calling C<ready>,
		855	works.
		856
		857	=back
		858
		859
		860	=head1 WINDOWS PROCESS EMULATION
		861
		862	A great many people seem to be confused about ithreads (for example, Chip
		863	Salzenberg called me unintelligent, incapable, stupid and gullible,
		864	while in the same mail making rather confused statements about perl
		865	ithreads (for example, that memory or files would be shared), showing his
		866	lack of understanding of this area - if it is hard to understand for Chip,
		867	it is probably not obvious to everybody).
		868
		869	What follows is an ultra-condensed version of my talk about threads in
		870	scripting languages given onthe perl workshop 2009:
		871
		872	The so-called "ithreads" were originally implemented for two reasons:
		873	first, to (badly) emulate unix processes on native win32 perls, and
		874	secondly, to replace the older, real thread model ("5.005-threads").
		875
		876	It does that by using threads instead of OS processes. The difference
		877	between processes and threads is that threads share memory (and other
		878	state, such as files) between threads within a single process, while
		879	processes do not share anything (at least not semantically). That
		880	means that modifications done by one thread are seen by others, while
		881	modifications by one process are not seen by other processes.
		882
		883	The "ithreads" work exactly like that: when creating a new ithreads
		884	process, all state is copied (memory is copied physically, files and code
		885	is copied logically). Afterwards, it isolates all modifications. On UNIX,
		886	the same behaviour can be achieved by using operating system processes,
		887	except that UNIX typically uses hardware built into the system to do this
		888	efficiently, while the windows process emulation emulates this hardware in
		889	software (rather efficiently, but of course it is still much slower than
		890	dedicated hardware).
		891
		892	As mentioned before, loading code, modifying code, modifying data
		893	structures and so on is only visible in the ithreads process doing the
		894	modification, not in other ithread processes within the same OS process.
		895
		896	This is why "ithreads" do not implement threads for perl at all, only
		897	processes. What makes it so bad is that on non-windows platforms, you can
		898	actually take advantage of custom hardware for this purpose (as evidenced
		899	by the forks module, which gives you the (i-) threads API, just much
		900	faster).
		901
		902	Sharing data is in the i-threads model is done by transfering data
		903	structures between threads using copying semantics, which is very slow -
		904	shared data simply does not exist. Benchmarks using i-threads which are
		905	communication-intensive show extremely bad behaviour with i-threads (in
		906	fact, so bad that Coro, which cannot take direct advantage of multiple
		907	CPUs, is often orders of magnitude faster because it shares data using
		908	real threads, refer to my talk for details).
		909
		910	As summary, i-threads use threads to implement processes, while
		911	the compatible forks module uses processes to emulate, uhm,
		912	processes. I-threads slow down every perl program when enabled, and
		913	outside of windows, serve no (or little) practical purpose, but
		914	disadvantages every single-threaded Perl program.
		915
		916	This is the reason that I try to avoid the name "ithreads", as it is
		917	misleading as it implies that it implements some kind of thread model for
		918	perl, and prefer the name "windows process emulation", which describes the
		919	actual use and behaviour of it much better.
575		920
576	=head1 SEE ALSO	921	=head1 SEE ALSO
577		922
		923	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		924
		925	Debugging: L<Coro::Debug>.
		926
578	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	927	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
579		928
580	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	929	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		930	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
581		931
582	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	932	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
583		933
584	Embedding: L<Coro:MakeMaker>	934	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		935	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		936	L<Coro::Select>.
		937
		938	XS API: L<Coro::MakeMaker>.
		939
		940	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
585		941
586	=head1 AUTHOR	942	=head1 AUTHOR
587		943
588	Marc Lehmann <schmorp@schmorp.de>	944	Marc Lehmann <schmorp@schmorp.de>
589	http://home.schmorp.de/	945	http://home.schmorp.de/

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Revision 1.140 by root, Thu Sep 27 16:25:10 2007 UTC vs.
Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC