1 |
root |
1.1 |
NAME |
2 |
|
|
Linux::AIO - linux-specific aio implemented using clone |
3 |
|
|
|
4 |
|
|
SYNOPSIS |
5 |
|
|
use Linux::AIO; |
6 |
|
|
|
7 |
|
|
DESCRIPTION |
8 |
root |
1.3 |
This module implements asynchronous I/O using the means available to |
9 |
|
|
Linux - clone. It does not hook into the POSIX aio_* functions because |
10 |
|
|
Linux does not yet support these in the kernel (even as of 2.6.12, only |
11 |
|
|
O_DIRECT files are supported) and even if, it would only allow aio_read |
12 |
|
|
and write, not open, stat and so on. |
13 |
root |
1.1 |
|
14 |
|
|
Instead, in this module a number of (non-posix) threads are started that |
15 |
|
|
execute your read/writes and signal their completion. You don't need |
16 |
|
|
thread support in your libc or perl, and the threads created by this |
17 |
|
|
module will not be visible to the pthreads library. |
18 |
|
|
|
19 |
|
|
NOTICE: the threads created by this module will automatically be killed |
20 |
|
|
when the thread calling min_parallel exits. Make sure you only ever call |
21 |
|
|
min_parallel from the same thread that loaded this module. |
22 |
|
|
|
23 |
root |
1.3 |
Although the module will work with in the presence of other threads, it |
24 |
|
|
is not reentrant, so use appropriate locking yourself. |
25 |
root |
1.1 |
|
26 |
|
|
Linux::AIO::min_parallel $nthreads |
27 |
|
|
Set the minimum number of AIO threads to $nthreads. The default is |
28 |
|
|
1, which means a single asynchronous operation can be done at one |
29 |
|
|
time (the number of outstanding operations, however, is unlimited). |
30 |
|
|
|
31 |
root |
1.2 |
It is recommended to keep the number of threads low, as some linux |
32 |
root |
1.1 |
kernel versions will scale negatively with the number of threads |
33 |
|
|
(higher parallelity => MUCH higher latency). |
34 |
|
|
|
35 |
root |
1.2 |
Linux::AIO::max_parallel $nthreads |
36 |
|
|
Sets the maximum number of AIO threads to $nthreads. If more than |
37 |
|
|
the specified number of threads are currently running, kill them. |
38 |
|
|
This function blocks until the limit is reached. |
39 |
|
|
|
40 |
|
|
This module automatically runs "max_parallel 0" at program end, to |
41 |
|
|
ensure that all threads are killed and that there are no outstanding |
42 |
|
|
requests. |
43 |
|
|
|
44 |
root |
1.1 |
$fileno = Linux::AIO::poll_fileno |
45 |
|
|
Return the *request result pipe filehandle*. This filehandle must be |
46 |
|
|
polled for reading by some mechanism outside this module (e.g. Event |
47 |
|
|
or select, see below). If the pipe becomes readable you have to call |
48 |
|
|
"poll_cb" to check the results. |
49 |
|
|
|
50 |
|
|
Linux::AIO::poll_cb |
51 |
|
|
Process all outstanding events on the result pipe. You have to call |
52 |
|
|
this regularly. Returns the number of events processed. Returns |
53 |
|
|
immediately when no events are outstanding. |
54 |
|
|
|
55 |
|
|
You can use Event to multiplex, e.g.: |
56 |
|
|
|
57 |
|
|
Event->io (fd => Linux::AIO::poll_fileno, |
58 |
|
|
poll => 'r', async => 1, |
59 |
|
|
cb => \&Linux::AIO::poll_cb ); |
60 |
|
|
|
61 |
root |
1.2 |
Linux::AIO::poll_wait |
62 |
|
|
Wait till the result filehandle becomes ready for reading (simply |
63 |
|
|
does a select on the filehandle. This is useful if you want to |
64 |
|
|
synchronously wait for some requests to finish). |
65 |
|
|
|
66 |
root |
1.1 |
Linux::AIO::nreqs |
67 |
|
|
Returns the number of requests currently outstanding. |
68 |
|
|
|
69 |
|
|
aio_open $pathname, $flags, $mode, $callback |
70 |
|
|
Asynchronously open or create a file and call the callback with the |
71 |
|
|
filedescriptor (NOT a perl filehandle, sorry for that, but watch |
72 |
|
|
out, this might change in the future). |
73 |
|
|
|
74 |
|
|
aio_close $fh, $callback |
75 |
|
|
Asynchronously close a file and call the callback with the result |
76 |
|
|
code. |
77 |
|
|
|
78 |
|
|
aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
79 |
|
|
aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
80 |
|
|
Reads or writes "length" bytes from the specified "fh" and "offset" |
81 |
|
|
into the scalar given by "data" and offset "dataoffset" and calls |
82 |
|
|
the callback without the actual number of bytes read (or "undef" on |
83 |
|
|
error). |
84 |
|
|
|
85 |
|
|
aio_stat $fh_or_path, $callback |
86 |
|
|
aio_lstat $fh, $callback |
87 |
|
|
Works like perl's "stat" or "lstat" in void context. The callback |
88 |
|
|
will be called after the stat and the results will be available |
89 |
|
|
using "stat _" or "-s _" etc... |
90 |
|
|
|
91 |
|
|
Currently, the stats are always 64-bit-stats, i.e. instead of |
92 |
|
|
returning an error when stat'ing a large file, the results will be |
93 |
|
|
silently truncated unless perl itself is compiled with large file |
94 |
|
|
support. |
95 |
|
|
|
96 |
|
|
aio_unlink $pathname, $callback |
97 |
|
|
Asynchronously unlink a file. |
98 |
|
|
|
99 |
|
|
BUGS |
100 |
|
|
This module has been extensively tested in a large and very busy |
101 |
|
|
webserver for many years now. |
102 |
|
|
|
103 |
|
|
- aio_open gives a fd, but all other functions expect a perl filehandle. |
104 |
|
|
|
105 |
|
|
SEE ALSO |
106 |
|
|
Coro. |
107 |
|
|
|
108 |
|
|
AUTHOR |
109 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
110 |
|
|
http://home.schmorp.de/ |
111 |
|
|
|