IO-AIO/AIO.pm

=head1 NAME

IO::AIO - Asynchronous Input/Output

=head1 SYNOPSIS

 use IO::AIO;

 aio_open "/etc/passwd", O_RDONLY, 0, sub {
    my ($fh) = @_;
    ...
 };

 aio_unlink "/tmp/file", sub { };

 aio_read $fh, 30000, 1024, $buffer, 0, sub {
    $_[0] > 0 or die "read error: $!";
 };

 # Event
 Event->io (fd => IO::AIO::poll_fileno,
            poll => 'r',
            cb => \&IO::AIO::poll_cb);

 # Glib/Gtk2
 add_watch Glib::IO IO::AIO::poll_fileno,
           in => sub { IO::AIO::poll_cb; 1 };

 # Tk
 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
                           readable => \&IO::AIO::poll_cb);

 # Danga::Socket
 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
                             \&IO::AIO::poll_cb);


=head1 DESCRIPTION

This module implements asynchronous I/O using whatever means your
operating system supports.

Currently, a number of threads are started that execute your read/writes
and signal their completion. You don't need thread support in your libc or
perl, and the threads created by this module will not be visible to the
pthreads library. In the future, this module might make use of the native
aio functions available on many operating systems. However, they are often
not well-supported (Linux doesn't allow them on normal files currently,
for example), and they would only support aio_read and aio_write, so the
remaining functionality would have to be implemented using threads anyway.

Although the module will work with in the presence of other threads, it is
currently not reentrant, so use appropriate locking yourself, always call
C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
C<aio_> functions) recursively.

=cut

package IO::AIO;

no warnings;

use base 'Exporter';

use Fcntl ();

BEGIN {
   $VERSION = 1.2;

   @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
                aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
   @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);

   require XSLoader;
   XSLoader::load IO::AIO, $VERSION;
}

=head1 FUNCTIONS

=head2 AIO FUNCTIONS

All the C<aio_*> calls are more or less thin wrappers around the syscall
with the same name (sans C<aio_>). The arguments are similar or identical,
and they all accept an additional (and optional) C<$callback> argument
which must be a code reference. This code reference will get called with
the syscall return code (e.g. most syscalls return C<-1> on error, unlike
perl, which usually delivers "false") as it's sole argument when the given
syscall has been executed asynchronously.

All functions expecting a filehandle keep a copy of the filehandle
internally until the request has finished.

The pathnames you pass to these routines I<must> be absolute and
encoded in byte form. The reason for the former is that at the time the
request is being executed, the current working directory could have
changed. Alternatively, you can make sure that you never change the
current working directory.

To encode pathnames to byte form, either make sure you either: a)
always pass in filenames you got from outside (command line, readdir
etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
your pathnames to the locale (or other) encoding in effect in the user
environment, d) use Glib::filename_from_unicode on unicode filenames or e)
use something else.

=over 4

=item aio_open $pathname, $flags, $mode, $callback

Asynchronously open or create a file and call the callback with a newly
created filehandle for the file.

The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
for an explanation.

The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
list. They are the same as used by C<sysopen>.

Likewise, C<$mode> specifies the mode of the newly created file, if it
didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
except that it is mandatory (i.e. use C<0> if you don't create new files,
and C<0666> or C<0777> if you do).

Example:

   aio_open "/etc/passwd", O_RDONLY, 0, sub {
      if ($_[0]) {
         print "open successful, fh is $_[0]\n";
         ...
      } else {
         die "open failed: $!\n";
      }
   };

=item aio_close $fh, $callback

Asynchronously close a file and call the callback with the result
code. I<WARNING:> although accepted, you should not pass in a perl
filehandle here, as perl will likely close the file descriptor another
time when the filehandle is destroyed. Normally, you can safely call perls
C<close> or just let filehandles go out of scope.

This is supposed to be a bug in the API, so that might change. It's
therefore best to avoid this function.

=item aio_read  $fh,$offset,$length, $data,$dataoffset,$callback

=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback

Reads or writes C<length> bytes from the specified C<fh> and C<offset>
into the scalar given by C<data> and offset C<dataoffset> and calls the
callback without the actual number of bytes read (or -1 on error, just
like the syscall).

Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
offset C<0> within the scalar:

   aio_read $fh, 7, 15, $buffer, 0, sub {
      $_[0] > 0 or die "read error: $!";
      print "read $_[0] bytes: <$buffer>\n";
   };

=item aio_readahead $fh,$offset,$length, $callback

C<aio_readahead> populates the page cache with data from a file so that
subsequent reads from that file will not block on disk I/O. The C<$offset>
argument specifies the starting point from which data is to be read and
C<$length> specifies the number of bytes to be read. I/O is performed in
whole pages, so that offset is effectively rounded down to a page boundary
and bytes are read up to the next page boundary greater than or equal to
(off-set+length). C<aio_readahead> does not read beyond the end of the
file. The current file offset of the file is left unchanged.

If that syscall doesn't exist (likely if your OS isn't Linux) it will be
emulated by simply reading the data, which would have a similar effect.

=item aio_stat  $fh_or_path, $callback

=item aio_lstat $fh, $callback

Works like perl's C<stat> or C<lstat> in void context. The callback will
be called after the stat and the results will be available using C<stat _>
or C<-s _> etc...

The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
for an explanation.

Currently, the stats are always 64-bit-stats, i.e. instead of returning an
error when stat'ing a large file, the results will be silently truncated
unless perl itself is compiled with large file support.

Example: Print the length of F</etc/passwd>:

   aio_stat "/etc/passwd", sub {
      $_[0] and die "stat failed: $!";
      print "size is ", -s _, "\n";
   };

=item aio_unlink $pathname, $callback

Asynchronously unlink (delete) a file and call the callback with the
result code.

=item aio_rmdir $pathname, $callback

Asynchronously rmdir (delete) a directory and call the callback with the
result code.

=item aio_fsync $fh, $callback

Asynchronously call fsync on the given filehandle and call the callback
with the fsync result code.

=item aio_fdatasync $fh, $callback

Asynchronously call fdatasync on the given filehandle and call the
callback with the fdatasync result code.

If this call isn't available because your OS lacks it or it couldn't be
detected, it will be emulated by calling C<fsync> instead.

=back

=head2 SUPPORT FUNCTIONS

=over 4

=item $fileno = IO::AIO::poll_fileno

Return the I<request result pipe file descriptor>. This filehandle must be
polled for reading by some mechanism outside this module (e.g. Event or
select, see below or the SYNOPSIS). If the pipe becomes readable you have
to call C<poll_cb> to check the results.

See C<poll_cb> for an example.

=item IO::AIO::poll_cb

Process all outstanding events on the result pipe. You have to call this
regularly. Returns the number of events processed. Returns immediately
when no events are outstanding.

Example: Install an Event watcher that automatically calls
IO::AIO::poll_cb with high priority:

   Event->io (fd => IO::AIO::poll_fileno,
              poll => 'r', async => 1,
              cb => \&IO::AIO::poll_cb);

=item IO::AIO::poll_wait

Wait till the result filehandle becomes ready for reading (simply does a
C<select> on the filehandle. This is useful if you want to synchronously wait
for some requests to finish).

See C<nreqs> for an example.

=item IO::AIO::nreqs

Returns the number of requests currently outstanding (i.e. for which their
callback has not been invoked yet).

Example: wait till there are no outstanding requests anymore:

   IO::AIO::poll_wait, IO::AIO::poll_cb
      while IO::AIO::nreqs;

=item IO::AIO::flush

Wait till all outstanding AIO requests have been handled.

Strictly equivalent to:

   IO::AIO::poll_wait, IO::AIO::poll_cb
      while IO::AIO::nreqs;

=item IO::AIO::poll

Waits until some requests have been handled.

Strictly equivalent to:

   IO::AIO::poll_wait, IO::AIO::poll_cb
      if IO::AIO::nreqs;

=item IO::AIO::min_parallel $nthreads

Set the minimum number of AIO threads to C<$nthreads>. The default is
C<1>, which means a single asynchronous operation can be done at one time
(the number of outstanding operations, however, is unlimited).

It is recommended to keep the number of threads low, as some Linux
kernel versions will scale negatively with the number of threads (higher
parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
threads should be fine.

Under normal circumstances you don't need to call this function, as this
module automatically starts some threads (the exact number might change,
and is currently 4).

=item IO::AIO::max_parallel $nthreads

Sets the maximum number of AIO threads to C<$nthreads>. If more than
the specified number of threads are currently running, kill them. This
function blocks until the limit is reached.

This module automatically runs C<max_parallel 0> at program end, to ensure
that all threads are killed and that there are no outstanding requests.

Under normal circumstances you don't need to call this function.

=item $oldnreqs = IO::AIO::max_outstanding $nreqs

Sets the maximum number of outstanding requests to C<$nreqs>. If you
try to queue up more than this number of requests, the caller will block until
some requests have been handled.

The default is very large, so normally there is no practical limit. If you
queue up many requests in a loop it it often improves speed if you set
this to a relatively low number, such as C<100>.

Under normal circumstances you don't need to call this function.

=back

=cut

# support function to convert a fd into a perl filehandle
sub _fd2fh {
   return undef if $_[0] < 0;

   # try to generate nice filehandles
   my $sym = "IO::AIO::fd#$_[0]";
   local *$sym;

   open *$sym, "+<&=$_[0]"      # usually works under any unix
      or open *$sym, "<&=$_[0]" # cygwin needs this
      or open *$sym, ">&=$_[0]" # or this
      or return undef;

   *$sym
}

min_parallel 4;

END {
   max_parallel 0;
}

1;

=head2 FORK BEHAVIOUR

Before the fork IO::AIO first handles all outstanding requests - if other
threads add requests during this period, this time is prolonged. It then
enters a quiescent state where no requests can be added in other threads
and no results will be processed. After the fork the parent simply leaves
the quiescent state and continues request processing, while the child will
free the request and result queue and start the same number of threads as
were in use by the parent.

=head1 SEE ALSO

L<Coro>, L<Linux::AIO>.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

Revision:	1.29
Committed:	Wed Aug 17 04:47:02 2005 UTC (18 years, 9 months ago) by root
Branch:	MAIN
Changes since 1.28:	+7 -4 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			IO::AIO - Asynchronous Input/Output
4
5			=head1 SYNOPSIS
6
7			use IO::AIO;
8
9	root	1.6	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10			my ($fh) = @_;
11			...
12			};
13
14			aio_unlink "/tmp/file", sub { };
15
16			aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	root	1.8	$_[0] > 0 or die "read error: $!";
18	root	1.6	};
19
20			# Event
21			Event->io (fd => IO::AIO::poll_fileno,
22	root	1.7	poll => 'r',
23	root	1.6	cb => \&IO::AIO::poll_cb);
24
25			# Glib/Gtk2
26			add_watch Glib::IO IO::AIO::poll_fileno,
27	root	1.22	in => sub { IO::AIO::poll_cb; 1 };
28	root	1.6
29			# Tk
30			Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31			readable => \&IO::AIO::poll_cb);
32
33	root	1.11	# Danga::Socket
34			Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
35			\&IO::AIO::poll_cb);
36
37
38	root	1.1	=head1 DESCRIPTION
39
40			This module implements asynchronous I/O using whatever means your
41	root	1.2	operating system supports.
42	root	1.1
43	root	1.2	Currently, a number of threads are started that execute your read/writes
44			and signal their completion. You don't need thread support in your libc or
45			perl, and the threads created by this module will not be visible to the
46			pthreads library. In the future, this module might make use of the native
47			aio functions available on many operating systems. However, they are often
48			not well-supported (Linux doesn't allow them on normal files currently,
49			for example), and they would only support aio_read and aio_write, so the
50			remaining functionality would have to be implemented using threads anyway.
51	root	1.1
52			Although the module will work with in the presence of other threads, it is
53	root	1.22	currently not reentrant, so use appropriate locking yourself, always call
54			C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
55			C<aio_> functions) recursively.
56	root	1.1
57			=cut
58
59			package IO::AIO;
60
61	root	1.23	no warnings;
62
63	root	1.1	use base 'Exporter';
64
65	root	1.2	use Fcntl ();
66
67	root	1.1	BEGIN {
68	root	1.28	$VERSION = 1.2;
69	root	1.1
70			@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
71	root	1.27	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
72	root	1.4	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
73	root	1.1
74			require XSLoader;
75			XSLoader::load IO::AIO, $VERSION;
76			}
77
78	root	1.5	=head1 FUNCTIONS
79	root	1.1
80	root	1.5	=head2 AIO FUNCTIONS
81	root	1.1
82	root	1.5	All the C<aio_*> calls are more or less thin wrappers around the syscall
83			with the same name (sans C<aio_>). The arguments are similar or identical,
84	root	1.14	and they all accept an additional (and optional) C<$callback> argument
85			which must be a code reference. This code reference will get called with
86			the syscall return code (e.g. most syscalls return C<-1> on error, unlike
87			perl, which usually delivers "false") as it's sole argument when the given
88			syscall has been executed asynchronously.
89	root	1.1
90	root	1.23	All functions expecting a filehandle keep a copy of the filehandle
91			internally until the request has finished.
92	root	1.1
93	root	1.28	The pathnames you pass to these routines I<must> be absolute and
94			encoded in byte form. The reason for the former is that at the time the
95			request is being executed, the current working directory could have
96			changed. Alternatively, you can make sure that you never change the
97			current working directory.
98
99			To encode pathnames to byte form, either make sure you either: a)
100			always pass in filenames you got from outside (command line, readdir
101			etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
102			your pathnames to the locale (or other) encoding in effect in the user
103			environment, d) use Glib::filename_from_unicode on unicode filenames or e)
104			use something else.
105	root	1.1
106	root	1.5	=over 4
107	root	1.1
108			=item aio_open $pathname, $flags, $mode, $callback
109
110	root	1.2	Asynchronously open or create a file and call the callback with a newly
111			created filehandle for the file.
112	root	1.1
113			The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
114			for an explanation.
115
116	root	1.20	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
117			list. They are the same as used by C<sysopen>.
118
119			Likewise, C<$mode> specifies the mode of the newly created file, if it
120			didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
121			except that it is mandatory (i.e. use C<0> if you don't create new files,
122			and C<0666> or C<0777> if you do).
123	root	1.1
124			Example:
125
126			aio_open "/etc/passwd", O_RDONLY, 0, sub {
127	root	1.2	if ($_[0]) {
128			print "open successful, fh is $_[0]\n";
129	root	1.1	...
130			} else {
131			die "open failed: $!\n";
132			}
133			};
134
135			=item aio_close $fh, $callback
136
137	root	1.2	Asynchronously close a file and call the callback with the result
138			code. I<WARNING:> although accepted, you should not pass in a perl
139	root	1.20	filehandle here, as perl will likely close the file descriptor another
140			time when the filehandle is destroyed. Normally, you can safely call perls
141			C<close> or just let filehandles go out of scope.
142
143			This is supposed to be a bug in the API, so that might change. It's
144			therefore best to avoid this function.
145	root	1.1
146			=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
147
148			=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
149
150			Reads or writes C<length> bytes from the specified C<fh> and C<offset>
151			into the scalar given by C<data> and offset C<dataoffset> and calls the
152			callback without the actual number of bytes read (or -1 on error, just
153			like the syscall).
154
155	root	1.17	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
156	root	1.1	offset C<0> within the scalar:
157
158			aio_read $fh, 7, 15, $buffer, 0, sub {
159	root	1.9	$_[0] > 0 or die "read error: $!";
160			print "read $_[0] bytes: <$buffer>\n";
161	root	1.1	};
162
163			=item aio_readahead $fh,$offset,$length, $callback
164
165	root	1.20	C<aio_readahead> populates the page cache with data from a file so that
166	root	1.1	subsequent reads from that file will not block on disk I/O. The C<$offset>
167			argument specifies the starting point from which data is to be read and
168			C<$length> specifies the number of bytes to be read. I/O is performed in
169			whole pages, so that offset is effectively rounded down to a page boundary
170			and bytes are read up to the next page boundary greater than or equal to
171	root	1.20	(off-set+length). C<aio_readahead> does not read beyond the end of the
172	root	1.1	file. The current file offset of the file is left unchanged.
173
174	root	1.26	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
175			emulated by simply reading the data, which would have a similar effect.
176
177	root	1.1	=item aio_stat $fh_or_path, $callback
178
179			=item aio_lstat $fh, $callback
180
181			Works like perl's C<stat> or C<lstat> in void context. The callback will
182			be called after the stat and the results will be available using C<stat _>
183			or C<-s _> etc...
184
185			The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
186			for an explanation.
187
188			Currently, the stats are always 64-bit-stats, i.e. instead of returning an
189			error when stat'ing a large file, the results will be silently truncated
190			unless perl itself is compiled with large file support.
191
192			Example: Print the length of F</etc/passwd>:
193
194			aio_stat "/etc/passwd", sub {
195			$_[0] and die "stat failed: $!";
196			print "size is ", -s _, "\n";
197			};
198
199			=item aio_unlink $pathname, $callback
200
201			Asynchronously unlink (delete) a file and call the callback with the
202			result code.
203
204	root	1.27	=item aio_rmdir $pathname, $callback
205
206			Asynchronously rmdir (delete) a directory and call the callback with the
207			result code.
208
209	root	1.1	=item aio_fsync $fh, $callback
210
211			Asynchronously call fsync on the given filehandle and call the callback
212			with the fsync result code.
213
214			=item aio_fdatasync $fh, $callback
215
216			Asynchronously call fdatasync on the given filehandle and call the
217	root	1.26	callback with the fdatasync result code.
218
219			If this call isn't available because your OS lacks it or it couldn't be
220			detected, it will be emulated by calling C<fsync> instead.
221	root	1.1
222	root	1.5	=back
223
224			=head2 SUPPORT FUNCTIONS
225
226			=over 4
227
228			=item $fileno = IO::AIO::poll_fileno
229
230	root	1.20	Return the I<request result pipe file descriptor>. This filehandle must be
231			polled for reading by some mechanism outside this module (e.g. Event or
232			select, see below or the SYNOPSIS). If the pipe becomes readable you have
233			to call C<poll_cb> to check the results.
234	root	1.5
235			See C<poll_cb> for an example.
236
237			=item IO::AIO::poll_cb
238
239			Process all outstanding events on the result pipe. You have to call this
240			regularly. Returns the number of events processed. Returns immediately
241			when no events are outstanding.
242
243	root	1.20	Example: Install an Event watcher that automatically calls
244			IO::AIO::poll_cb with high priority:
245	root	1.5
246			Event->io (fd => IO::AIO::poll_fileno,
247			poll => 'r', async => 1,
248			cb => \&IO::AIO::poll_cb);
249
250			=item IO::AIO::poll_wait
251
252			Wait till the result filehandle becomes ready for reading (simply does a
253	root	1.20	C<select> on the filehandle. This is useful if you want to synchronously wait
254	root	1.5	for some requests to finish).
255
256			See C<nreqs> for an example.
257
258			=item IO::AIO::nreqs
259
260	root	1.20	Returns the number of requests currently outstanding (i.e. for which their
261			callback has not been invoked yet).
262	root	1.5
263			Example: wait till there are no outstanding requests anymore:
264
265			IO::AIO::poll_wait, IO::AIO::poll_cb
266			while IO::AIO::nreqs;
267
268	root	1.12	=item IO::AIO::flush
269
270			Wait till all outstanding AIO requests have been handled.
271
272	root	1.13	Strictly equivalent to:
273
274			IO::AIO::poll_wait, IO::AIO::poll_cb
275			while IO::AIO::nreqs;
276
277			=item IO::AIO::poll
278
279			Waits until some requests have been handled.
280
281			Strictly equivalent to:
282
283			IO::AIO::poll_wait, IO::AIO::poll_cb
284			if IO::AIO::nreqs;
285
286	root	1.5	=item IO::AIO::min_parallel $nthreads
287
288			Set the minimum number of AIO threads to C<$nthreads>. The default is
289			C<1>, which means a single asynchronous operation can be done at one time
290			(the number of outstanding operations, however, is unlimited).
291
292			It is recommended to keep the number of threads low, as some Linux
293			kernel versions will scale negatively with the number of threads (higher
294			parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
295			threads should be fine.
296
297			Under normal circumstances you don't need to call this function, as this
298			module automatically starts some threads (the exact number might change,
299			and is currently 4).
300
301			=item IO::AIO::max_parallel $nthreads
302
303			Sets the maximum number of AIO threads to C<$nthreads>. If more than
304			the specified number of threads are currently running, kill them. This
305			function blocks until the limit is reached.
306
307			This module automatically runs C<max_parallel 0> at program end, to ensure
308			that all threads are killed and that there are no outstanding requests.
309
310			Under normal circumstances you don't need to call this function.
311
312			=item $oldnreqs = IO::AIO::max_outstanding $nreqs
313
314			Sets the maximum number of outstanding requests to C<$nreqs>. If you
315			try to queue up more than this number of requests, the caller will block until
316			some requests have been handled.
317
318			The default is very large, so normally there is no practical limit. If you
319			queue up many requests in a loop it it often improves speed if you set
320			this to a relatively low number, such as C<100>.
321
322			Under normal circumstances you don't need to call this function.
323
324			=back
325
326	root	1.1	=cut
327
328	root	1.2	# support function to convert a fd into a perl filehandle
329			sub _fd2fh {
330			return undef if $_[0] < 0;
331
332	root	1.23	# try to generate nice filehandles
333			my $sym = "IO::AIO::fd#$_[0]";
334			local *$sym;
335	root	1.25
336	root	1.27	open *$sym, "+<&=$_[0]" # usually works under any unix
337			or open *$sym, "<&=$_[0]" # cygwin needs this
338			or open *$sym, ">&=$_[0]" # or this
339	root	1.2	or return undef;
340
341	root	1.23	*$sym
342	root	1.2	}
343
344	root	1.1	min_parallel 4;
345
346			END {
347			max_parallel 0;
348			}
349
350			1;
351
352	root	1.27	=head2 FORK BEHAVIOUR
353
354	root	1.29	Before the fork IO::AIO first handles all outstanding requests - if other
355			threads add requests during this period, this time is prolonged. It then
356			enters a quiescent state where no requests can be added in other threads
357			and no results will be processed. After the fork the parent simply leaves
358			the quiescent state and continues request processing, while the child will
359			free the request and result queue and start the same number of threads as
360			were in use by the parent.
361	root	1.27
362	root	1.1	=head1 SEE ALSO
363
364			L<Coro>, L<Linux::AIO>.
365
366			=head1 AUTHOR
367
368			Marc Lehmann <schmorp@schmorp.de>
369			http://home.schmorp.de/
370
371			=cut
372