… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use IO::AIO; |
7 | use IO::AIO; |
8 | |
8 | |
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9 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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10 | my ($fh) = @_; |
|
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11 | ... |
|
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12 | }; |
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13 | |
|
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14 | aio_unlink "/tmp/file", sub { }; |
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15 | |
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16 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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17 | $_[0] > 0 or die "read error: $!"; |
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18 | }; |
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19 | |
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20 | # Event |
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21 | Event->io (fd => IO::AIO::poll_fileno, |
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22 | poll => 'r', |
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23 | cb => \&IO::AIO::poll_cb); |
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24 | |
|
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25 | # Glib/Gtk2 |
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26 | add_watch Glib::IO IO::AIO::poll_fileno, |
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27 | in => sub { IO::AIO::poll_cb, 1 }; |
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28 | |
|
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29 | # Tk |
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30 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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31 | readable => \&IO::AIO::poll_cb); |
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32 | |
|
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33 | # Danga::Socket |
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34 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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35 | \&IO::AIO::poll_cb); |
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36 | |
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37 | |
9 | =head1 DESCRIPTION |
38 | =head1 DESCRIPTION |
10 | |
39 | |
11 | This module implements asynchronous I/O using whatever means your |
40 | This module implements asynchronous I/O using whatever means your |
12 | operating system supports. Currently, it falls back to Linux::AIO if that |
41 | operating system supports. |
13 | module is available, or uses pthreads to emulato aio functionality. |
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14 | |
42 | |
15 | Currently, in this module a number of threads are started that execute |
43 | Currently, a number of threads are started that execute your read/writes |
16 | your read/writes and signal their completion. You don't need thread |
44 | and signal their completion. You don't need thread support in your libc or |
17 | support in your libc or perl, and the threads created by this module will |
45 | perl, and the threads created by this module will not be visible to the |
18 | not be visible to the pthreads library. |
46 | pthreads library. In the future, this module might make use of the native |
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47 | aio functions available on many operating systems. However, they are often |
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48 | not well-supported (Linux doesn't allow them on normal files currently, |
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49 | for example), and they would only support aio_read and aio_write, so the |
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50 | remaining functionality would have to be implemented using threads anyway. |
19 | |
51 | |
20 | Although the module will work with in the presence of other threads, it is |
52 | Although the module will work with in the presence of other threads, it is |
21 | not reentrant, so use appropriate locking yourself. |
53 | currently not reentrant, so use appropriate locking yourself. |
22 | |
54 | |
23 | =head2 API NOTES |
55 | =cut |
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56 | |
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57 | package IO::AIO; |
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58 | |
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59 | use base 'Exporter'; |
|
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60 | |
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61 | use Fcntl (); |
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62 | |
|
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63 | BEGIN { |
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64 | $VERSION = 0.4; |
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65 | |
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66 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
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67 | aio_fsync aio_fdatasync aio_readahead); |
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68 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
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69 | |
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70 | require XSLoader; |
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71 | XSLoader::load IO::AIO, $VERSION; |
|
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72 | } |
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73 | |
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74 | =head1 FUNCTIONS |
|
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75 | |
|
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76 | =head2 AIO FUNCTIONS |
24 | |
77 | |
25 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
78 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
26 | with the same name (sans C<aio_>). The arguments are similar or identical, |
79 | with the same name (sans C<aio_>). The arguments are similar or identical, |
27 | and they all accept an additional C<$callback> argument which must be |
80 | and they all accept an additional (and optional) C<$callback> argument |
28 | a code reference. This code reference will get called with the syscall |
81 | which must be a code reference. This code reference will get called with |
29 | return code (e.g. most syscalls return C<-1> on error, unlike perl, which |
82 | the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
30 | usually delivers "false") as it's sole argument when the given syscall has |
83 | perl, which usually delivers "false") as it's sole argument when the given |
31 | been executed asynchronously. |
84 | syscall has been executed asynchronously. |
32 | |
85 | |
33 | All functions that expect a filehandle will also accept a file descriptor. |
86 | All functions that expect a filehandle will also accept a file descriptor. |
34 | |
87 | |
35 | The filenames you pass to these routines I<must> be absolute. The reason |
88 | The filenames you pass to these routines I<must> be absolute. The reason |
36 | is that at the time the request is being executed, the current working |
89 | is that at the time the request is being executed, the current working |
37 | directory could have changed. Alternatively, you can make sure that you |
90 | directory could have changed. Alternatively, you can make sure that you |
38 | never change the current working directory. |
91 | never change the current working directory. |
39 | |
92 | |
40 | =over 4 |
93 | =over 4 |
41 | |
94 | |
42 | =cut |
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43 | |
|
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44 | package IO::AIO; |
|
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45 | |
|
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46 | use base 'Exporter'; |
|
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47 | |
|
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48 | BEGIN { |
|
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49 | $VERSION = 0.1; |
|
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50 | |
|
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51 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
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52 | aio_fsync aio_fdatasync aio_readahead); |
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53 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs); |
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54 | |
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55 | require XSLoader; |
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56 | XSLoader::load IO::AIO, $VERSION; |
|
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57 | } |
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58 | |
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59 | =item IO::AIO::min_parallel $nthreads |
|
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60 | |
|
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61 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
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62 | C<1>, which means a single asynchronous operation can be done at one time |
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63 | (the number of outstanding operations, however, is unlimited). |
|
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64 | |
|
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65 | It is recommended to keep the number of threads low, as some linux |
|
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66 | kernel versions will scale negatively with the number of threads (higher |
|
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67 | parallelity => MUCH higher latency). |
|
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68 | |
|
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69 | Under normal circumstances you don't need to call this function, as this |
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70 | module automatically starts a single async thread. |
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71 | |
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72 | =item IO::AIO::max_parallel $nthreads |
|
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73 | |
|
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74 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
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75 | the specified number of threads are currently running, kill them. This |
|
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76 | function blocks until the limit is reached. |
|
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77 | |
|
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78 | This module automatically runs C<max_parallel 0> at program end, to ensure |
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79 | that all threads are killed and that there are no outstanding requests. |
|
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80 | |
|
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81 | Under normal circumstances you don't need to call this function. |
|
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82 | |
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83 | =item $fileno = IO::AIO::poll_fileno |
|
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84 | |
|
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85 | Return the I<request result pipe filehandle>. This filehandle must be |
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86 | polled for reading by some mechanism outside this module (e.g. Event |
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87 | or select, see below). If the pipe becomes readable you have to call |
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88 | C<poll_cb> to check the results. |
|
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89 | |
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90 | See C<poll_cb> for an example. |
|
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91 | |
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92 | =item IO::AIO::poll_cb |
|
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93 | |
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94 | Process all outstanding events on the result pipe. You have to call this |
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95 | regularly. Returns the number of events processed. Returns immediately |
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96 | when no events are outstanding. |
|
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97 | |
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98 | You can use Event to multiplex, e.g.: |
|
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99 | |
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100 | Event->io (fd => IO::AIO::poll_fileno, |
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101 | poll => 'r', async => 1, |
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102 | cb => \&IO::AIO::poll_cb); |
|
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103 | |
|
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104 | =item IO::AIO::poll_wait |
|
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105 | |
|
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106 | Wait till the result filehandle becomes ready for reading (simply does a |
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107 | select on the filehandle. This is useful if you want to synchronously wait |
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108 | for some requests to finish). |
|
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109 | |
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110 | See C<nreqs> for an example. |
|
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111 | |
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112 | =item IO::AIO::nreqs |
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113 | |
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114 | Returns the number of requests currently outstanding. |
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115 | |
|
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116 | Example: wait till there are no outstanding requests anymore: |
|
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117 | |
|
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118 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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119 | while IO::AIO::nreqs; |
|
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120 | |
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121 | =item aio_open $pathname, $flags, $mode, $callback |
95 | =item aio_open $pathname, $flags, $mode, $callback |
122 | |
96 | |
123 | Asynchronously open or create a file and call the callback with the |
97 | Asynchronously open or create a file and call the callback with a newly |
124 | filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this |
98 | created filehandle for the file. |
125 | might change in the future). |
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126 | |
99 | |
127 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
100 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
128 | for an explanation. |
101 | for an explanation. |
129 | |
102 | |
130 | The C<$mode> argument is a bitmask. See the C<Fcntl> module for a |
103 | The C<$mode> argument is a bitmask. See the C<Fcntl> module for a |
131 | list. They are the same as used in C<sysopen>. |
104 | list. They are the same as used in C<sysopen>. |
132 | |
105 | |
133 | Example: |
106 | Example: |
134 | |
107 | |
135 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
108 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
136 | if ($_[0] >= 0) { |
109 | if ($_[0]) { |
137 | open my $fh, "<&$_[0]"; # create a copy for perl |
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138 | aio_close $_[0], sub { }; # close the aio handle |
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139 | print "open successful, fh is $fh\n"; |
110 | print "open successful, fh is $_[0]\n"; |
140 | ... |
111 | ... |
141 | } else { |
112 | } else { |
142 | die "open failed: $!\n"; |
113 | die "open failed: $!\n"; |
143 | } |
114 | } |
144 | }; |
115 | }; |
145 | |
116 | |
146 | =item aio_close $fh, $callback |
117 | =item aio_close $fh, $callback |
147 | |
118 | |
148 | Asynchronously close a file and call the callback with the result code. |
119 | Asynchronously close a file and call the callback with the result |
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120 | code. I<WARNING:> although accepted, you should not pass in a perl |
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121 | filehandle here, as perl will likely close the file descriptor itself when |
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122 | the filehandle is destroyed. Normally, you can safely call perls C<close> |
|
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123 | or just let filehandles go out of scope. |
149 | |
124 | |
150 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
125 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
151 | |
126 | |
152 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
127 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
153 | |
128 | |
154 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
129 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
155 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
130 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
156 | callback without the actual number of bytes read (or -1 on error, just |
131 | callback without the actual number of bytes read (or -1 on error, just |
157 | like the syscall). |
132 | like the syscall). |
158 | |
133 | |
159 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
134 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
160 | offset C<0> within the scalar: |
135 | offset C<0> within the scalar: |
161 | |
136 | |
162 | aio_read $fh, 7, 15, $buffer, 0, sub { |
137 | aio_read $fh, 7, 15, $buffer, 0, sub { |
163 | $_[0] >= 0 or die "read error: $!"; |
138 | $_[0] > 0 or die "read error: $!"; |
164 | print "read <$buffer>\n"; |
139 | print "read $_[0] bytes: <$buffer>\n"; |
165 | }; |
140 | }; |
166 | |
141 | |
167 | =item aio_readahead $fh,$offset,$length, $callback |
142 | =item aio_readahead $fh,$offset,$length, $callback |
168 | |
143 | |
169 | Asynchronously reads the specified byte range into the page cache, using |
144 | Asynchronously reads the specified byte range into the page cache, using |
170 | the C<readahead> syscall. If that syscall doesn't exist the status will be |
145 | the C<readahead> syscall. If that syscall doesn't exist (likely if your OS |
171 | C<-1> and C<$!> is set to ENOSYS. |
146 | isn't Linux) the status will be C<-1> and C<$!> is set to ENOSYS. |
172 | |
147 | |
173 | readahead() populates the page cache with data from a file so that |
148 | readahead() populates the page cache with data from a file so that |
174 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
149 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
175 | argument specifies the starting point from which data is to be read and |
150 | argument specifies the starting point from which data is to be read and |
176 | C<$length> specifies the number of bytes to be read. I/O is performed in |
151 | C<$length> specifies the number of bytes to be read. I/O is performed in |
… | |
… | |
214 | =item aio_fdatasync $fh, $callback |
189 | =item aio_fdatasync $fh, $callback |
215 | |
190 | |
216 | Asynchronously call fdatasync on the given filehandle and call the |
191 | Asynchronously call fdatasync on the given filehandle and call the |
217 | callback with the fdatasync result code. |
192 | callback with the fdatasync result code. |
218 | |
193 | |
|
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194 | =back |
|
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195 | |
|
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196 | =head2 SUPPORT FUNCTIONS |
|
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197 | |
|
|
198 | =over 4 |
|
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199 | |
|
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200 | =item $fileno = IO::AIO::poll_fileno |
|
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201 | |
|
|
202 | Return the I<request result pipe filehandle>. This filehandle must be |
|
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203 | polled for reading by some mechanism outside this module (e.g. Event |
|
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204 | or select, see below). If the pipe becomes readable you have to call |
|
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205 | C<poll_cb> to check the results. |
|
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206 | |
|
|
207 | See C<poll_cb> for an example. |
|
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208 | |
|
|
209 | =item IO::AIO::poll_cb |
|
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210 | |
|
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211 | Process all outstanding events on the result pipe. You have to call this |
|
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212 | regularly. Returns the number of events processed. Returns immediately |
|
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213 | when no events are outstanding. |
|
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214 | |
|
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215 | You can use Event to multiplex, e.g.: |
|
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216 | |
|
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217 | Event->io (fd => IO::AIO::poll_fileno, |
|
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218 | poll => 'r', async => 1, |
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219 | cb => \&IO::AIO::poll_cb); |
|
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220 | |
|
|
221 | =item IO::AIO::poll_wait |
|
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222 | |
|
|
223 | Wait till the result filehandle becomes ready for reading (simply does a |
|
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224 | select on the filehandle. This is useful if you want to synchronously wait |
|
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225 | for some requests to finish). |
|
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226 | |
|
|
227 | See C<nreqs> for an example. |
|
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228 | |
|
|
229 | =item IO::AIO::nreqs |
|
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230 | |
|
|
231 | Returns the number of requests currently outstanding. |
|
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232 | |
|
|
233 | Example: wait till there are no outstanding requests anymore: |
|
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234 | |
|
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235 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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236 | while IO::AIO::nreqs; |
|
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237 | |
|
|
238 | =item IO::AIO::flush |
|
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239 | |
|
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240 | Wait till all outstanding AIO requests have been handled. |
|
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241 | |
|
|
242 | Strictly equivalent to: |
|
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243 | |
|
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244 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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245 | while IO::AIO::nreqs; |
|
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246 | |
|
|
247 | =item IO::AIO::poll |
|
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248 | |
|
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249 | Waits until some requests have been handled. |
|
|
250 | |
|
|
251 | Strictly equivalent to: |
|
|
252 | |
|
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253 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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254 | if IO::AIO::nreqs; |
|
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255 | |
|
|
256 | =item IO::AIO::min_parallel $nthreads |
|
|
257 | |
|
|
258 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
|
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259 | C<1>, which means a single asynchronous operation can be done at one time |
|
|
260 | (the number of outstanding operations, however, is unlimited). |
|
|
261 | |
|
|
262 | It is recommended to keep the number of threads low, as some Linux |
|
|
263 | kernel versions will scale negatively with the number of threads (higher |
|
|
264 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
|
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265 | threads should be fine. |
|
|
266 | |
|
|
267 | Under normal circumstances you don't need to call this function, as this |
|
|
268 | module automatically starts some threads (the exact number might change, |
|
|
269 | and is currently 4). |
|
|
270 | |
|
|
271 | =item IO::AIO::max_parallel $nthreads |
|
|
272 | |
|
|
273 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
|
|
274 | the specified number of threads are currently running, kill them. This |
|
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275 | function blocks until the limit is reached. |
|
|
276 | |
|
|
277 | This module automatically runs C<max_parallel 0> at program end, to ensure |
|
|
278 | that all threads are killed and that there are no outstanding requests. |
|
|
279 | |
|
|
280 | Under normal circumstances you don't need to call this function. |
|
|
281 | |
|
|
282 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
|
|
283 | |
|
|
284 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
|
|
285 | try to queue up more than this number of requests, the caller will block until |
|
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286 | some requests have been handled. |
|
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287 | |
|
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288 | The default is very large, so normally there is no practical limit. If you |
|
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289 | queue up many requests in a loop it it often improves speed if you set |
|
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290 | this to a relatively low number, such as C<100>. |
|
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291 | |
|
|
292 | Under normal circumstances you don't need to call this function. |
|
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293 | |
|
|
294 | =back |
|
|
295 | |
219 | =cut |
296 | =cut |
|
|
297 | |
|
|
298 | # support function to convert a fd into a perl filehandle |
|
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299 | sub _fd2fh { |
|
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300 | return undef if $_[0] < 0; |
|
|
301 | |
|
|
302 | # try to be perl5.6-compatible |
|
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303 | local *AIO_FH; |
|
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304 | open AIO_FH, "+<&=$_[0]" |
|
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305 | or return undef; |
|
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306 | |
|
|
307 | *AIO_FH |
|
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308 | } |
220 | |
309 | |
221 | min_parallel 4; |
310 | min_parallel 4; |
222 | |
311 | |
223 | END { |
312 | END { |
224 | max_parallel 0; |
313 | max_parallel 0; |
225 | } |
314 | } |
226 | |
315 | |
227 | 1; |
316 | 1; |
228 | |
317 | |
229 | =back |
|
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230 | |
|
|
231 | =head1 BUGS |
|
|
232 | |
|
|
233 | - aio_open gives a fd, but all other functions expect a perl filehandle. |
|
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234 | |
|
|
235 | =head1 SEE ALSO |
318 | =head1 SEE ALSO |
236 | |
319 | |
237 | L<Coro>, L<Linux::AIO>. |
320 | L<Coro>, L<Linux::AIO>. |
238 | |
321 | |
239 | =head1 AUTHOR |
322 | =head1 AUTHOR |