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Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.2 by root, Tue Aug 14 18:06:37 2001 UTC vs.
Revision 1.28 by root, Sat Jul 9 04:11:30 2005 UTC

… …
6 6
7 use Linux::AIO; 7 use Linux::AIO;
8 8
9=head1 DESCRIPTION 9=head1 DESCRIPTION
10 10
11This module implements asynchronous I/O using the means available to Linux
12- clone. It does not hook into the POSIX aio_* functions because Linux
13does not yet support these in the kernel (even as of 2.6.12, only O_DIRECT
14files are supported) and even if, it would only allow aio_read and write,
15not open, stat and so on.
16
17Instead, in this module a number of (non-posix) threads are started that
18execute your read/writes and signal their completion. You don't need
19thread support in your libc or perl, and the threads created by this
20module will not be visible to the pthreads library.
21
22NOTICE: the threads created by this module will automatically be killed
23when the thread calling min_parallel exits. Make sure you only ever call
24min_parallel from the same thread that loaded this module.
25
26Although the module will work with in the presence of other threads, it is
27not reentrant, so use appropriate locking yourself.
28
11=over 4 29=over 4
12 30
13=cut 31=cut
14 32
15package Linux::AIO; 33package Linux::AIO;
16 34
17use base 'Exporter'; 35use base 'Exporter';
18 36
19BEGIN { 37BEGIN {
20 $VERSION = 0.001; 38 $VERSION = 1.61;
21 39
22 @EXPORT = qw(aio_read aio_write); 40 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink);
23 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs); 41 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);
24 42
25 require XSLoader; 43 require XSLoader;
26 XSLoader::load Linux::AIO, $VERSION; 44 XSLoader::load Linux::AIO, $VERSION;
27} 45}
28 46
29=item Linux::AIO::min_parallel($nthreads) 47=item Linux::AIO::min_parallel $nthreads
30 48
31Set the minimum number of AIO threads to $nthreads. 49Set the minimum number of AIO threads to C<$nthreads>. The default is
50C<1>, which means a single asynchronous operation can be done at one time
51(the number of outstanding operations, however, is unlimited).
32 52
33=cut 53It is recommended to keep the number of threads low, as some linux
54kernel versions will scale negatively with the number of threads (higher
55parallelity => MUCH higher latency).
34 56
35=item aio_read($fh,$offset,$length, $data,$dataoffset,$callback) 57=item Linux::AIO::max_parallel $nthreads
36aio_write($fh,$offset,$length, $data,$dataoffset,$callback)
37 58
38Reads or writes C<length> bytes from the specified C<fh> and C<offset> 59Sets the maximum number of AIO threads to C<$nthreads>. If more than
39into the scalar given by C<data> and offset C<dataoffset> and calls the 60the specified number of threads are currently running, kill them. This
40callback without the actual number of bytes read (or undef on error). 61function blocks until the limit is reached.
62
63This module automatically runs C<max_parallel 0> at program end, to ensure
64that all threads are killed and that there are no outstanding requests.
41 65
42=item $fileno = Linux::AIO::poll_fileno 66=item $fileno = Linux::AIO::poll_fileno
43 67
44Return the request result pipe filehandle. This filehandle must be polled 68Return the I<request result pipe filehandle>. This filehandle must be
45for reading. If the pipe becomes readable you have to call C<poll_cb>. 69polled for reading by some mechanism outside this module (e.g. Event
70or select, see below). If the pipe becomes readable you have to call
71C<poll_cb> to check the results.
46 72
47=item Linux::AIO::poll_cb 73=item Linux::AIO::poll_cb
48 74
49Process all outstanding events on the result pipe. You have to call this 75Process all outstanding events on the result pipe. You have to call this
50regularly. Returns the number of events processed. 76regularly. Returns the number of events processed. Returns immediately
77when no events are outstanding.
78
79You can use Event to multiplex, e.g.:
80
81 Event->io (fd => Linux::AIO::poll_fileno,
82 poll => 'r', async => 1,
83 cb => \&Linux::AIO::poll_cb );
84
85=item Linux::AIO::poll_wait
86
87Wait till the result filehandle becomes ready for reading (simply does a
88select on the filehandle. This is useful if you want to synchronously wait
89for some requests to finish).
51 90
52=item Linux::AIO::nreqs 91=item Linux::AIO::nreqs
53 92
54Returns the number of requests currently outstanding. 93Returns the number of requests currently outstanding.
55 94
95=item aio_open $pathname, $flags, $mode, $callback
96
97Asynchronously open or create a file and call the callback with the
98filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
99might change in the future).
100
101=item aio_close $fh, $callback
102
103Asynchronously close a file and call the callback with the result code.
104
105=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
106
107=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
108
109Reads or writes C<length> bytes from the specified C<fh> and C<offset>
110into the scalar given by C<data> and offset C<dataoffset> and calls the
111callback without the actual number of bytes read (or C<undef> on error).
112
113=item aio_stat $fh_or_path, $callback
114
115=item aio_lstat $fh, $callback
116
117Works like perl's C<stat> or C<lstat> in void context. The callback will
118be called after the stat and the results will be available using C<stat _>
119or C<-s _> etc...
120
121Currently, the stats are always 64-bit-stats, i.e. instead of returning an
122error when stat'ing a large file, the results will be silently truncated
123unless perl itself is compiled with large file support.
124
125=item aio_unlink $pathname, $callback
126
127Asynchronously unlink a file.
128
56=cut 129=cut
130
131min_parallel 1;
57 132
58END { 133END {
59 max_parallel 0; 134 max_parallel 0;
60} 135}
61 136
… …
63 138
64=back 139=back
65 140
66=head1 BUGS 141=head1 BUGS
67 142
68This module has not yet been extensively tested. Watch out! 143This module has been extensively tested in a large and very busy webserver
144for many years now.
69 145
70This module does not use the aio_* posix functions because a) linux does 146 - aio_open gives a fd, but all other functions expect a perl filehandle.
71not have aio, b) the existing aio_* functions use pthreads, which are too
72buggy for my usage.
73 147
74=head1 SEE ALSO 148=head1 SEE ALSO
75 149
76L<Coro>. 150L<Coro>.
77 151
78=head1 AUTHOR 152=head1 AUTHOR
79 153
80 Marc Lehmann <pcg@goof.com> 154 Marc Lehmann <schmorp@schmorp.de>
81 http://www.goof.com/pcg/marc/ 155 http://home.schmorp.de/
82 156
83=cut 157=cut
84 158

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