… | |
… | |
3 | IO::AIO - Asynchronous Input/Output |
3 | IO::AIO - Asynchronous Input/Output |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use IO::AIO; |
7 | use IO::AIO; |
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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 | |
8 | |
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. |
41 | operating system supports. |
… | |
… | |
21 | remaining functionality would have to be implemented using threads anyway. |
50 | remaining functionality would have to be implemented using threads anyway. |
22 | |
51 | |
23 | 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 |
24 | currently not reentrant, so use appropriate locking yourself. |
53 | currently not reentrant, so use appropriate locking yourself. |
25 | |
54 | |
26 | =head2 API NOTES |
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27 | |
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28 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
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29 | with the same name (sans C<aio_>). The arguments are similar or identical, |
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30 | and they all accept an additional C<$callback> argument which must be |
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31 | a code reference. This code reference will get called with the syscall |
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32 | return code (e.g. most syscalls return C<-1> on error, unlike perl, which |
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33 | usually delivers "false") as it's sole argument when the given syscall has |
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34 | been executed asynchronously. |
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35 | |
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36 | All functions that expect a filehandle will also accept a file descriptor. |
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37 | |
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38 | The filenames you pass to these routines I<must> be absolute. The reason |
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39 | is that at the time the request is being executed, the current working |
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40 | directory could have changed. Alternatively, you can make sure that you |
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41 | never change the current working directory. |
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42 | |
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43 | =over 4 |
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44 | |
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45 | =cut |
55 | =cut |
46 | |
56 | |
47 | package IO::AIO; |
57 | package IO::AIO; |
48 | |
58 | |
49 | use base 'Exporter'; |
59 | use base 'Exporter'; |
50 | |
60 | |
51 | use Fcntl (); |
61 | use Fcntl (); |
52 | |
62 | |
53 | BEGIN { |
63 | BEGIN { |
54 | $VERSION = 0.2; |
64 | $VERSION = 0.5; |
55 | |
65 | |
56 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
66 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
57 | aio_fsync aio_fdatasync aio_readahead); |
67 | aio_fsync aio_fdatasync aio_readahead); |
58 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
68 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
59 | |
69 | |
60 | require XSLoader; |
70 | require XSLoader; |
61 | XSLoader::load IO::AIO, $VERSION; |
71 | XSLoader::load IO::AIO, $VERSION; |
62 | } |
72 | } |
63 | |
73 | |
64 | =item IO::AIO::min_parallel $nthreads |
74 | =head1 FUNCTIONS |
65 | |
75 | |
66 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
76 | =head2 AIO FUNCTIONS |
67 | C<1>, which means a single asynchronous operation can be done at one time |
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68 | (the number of outstanding operations, however, is unlimited). |
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69 | |
77 | |
70 | It is recommended to keep the number of threads low, as some Linux |
78 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
71 | kernel versions will scale negatively with the number of threads (higher |
79 | with the same name (sans C<aio_>). The arguments are similar or identical, |
72 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
80 | and they all accept an additional (and optional) C<$callback> argument |
73 | threads should be fine. |
81 | which must be a code reference. This code reference will get called with |
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82 | the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
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83 | perl, which usually delivers "false") as it's sole argument when the given |
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84 | syscall has been executed asynchronously. |
74 | |
85 | |
75 | Under normal circumstances you don't need to call this function, as this |
86 | All functions that expect a filehandle will also accept a file descriptor. |
76 | module automatically starts some threads (the exact number might change, |
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77 | and is currently 4). |
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78 | |
87 | |
79 | =item IO::AIO::max_parallel $nthreads |
88 | The filenames you pass to these routines I<must> be absolute. The reason |
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89 | for this is that at the time the request is being executed, the current |
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90 | working directory could have changed. Alternatively, you can make sure |
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91 | that you never change the current working directory. |
80 | |
92 | |
81 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
93 | =over 4 |
82 | the specified number of threads are currently running, kill them. This |
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83 | function blocks until the limit is reached. |
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84 | |
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85 | This module automatically runs C<max_parallel 0> at program end, to ensure |
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86 | that all threads are killed and that there are no outstanding requests. |
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87 | |
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88 | Under normal circumstances you don't need to call this function. |
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89 | |
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90 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
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91 | |
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92 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
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93 | try to queue up more than this number of requests, the caller will block until |
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94 | some requests have been handled. |
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95 | |
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96 | The default is very large, so normally there is no practical limit. If you |
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97 | queue up many requests in a loop it it often improves speed if you set |
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98 | this to a relatively low number, such as C<100>. |
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99 | |
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100 | Under normal circumstances you don't need to call this function. |
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101 | |
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102 | =item $fileno = IO::AIO::poll_fileno |
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103 | |
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104 | Return the I<request result pipe filehandle>. This filehandle must be |
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105 | polled for reading by some mechanism outside this module (e.g. Event |
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106 | or select, see below). If the pipe becomes readable you have to call |
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107 | C<poll_cb> to check the results. |
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108 | |
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109 | See C<poll_cb> for an example. |
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110 | |
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111 | =item IO::AIO::poll_cb |
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112 | |
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113 | Process all outstanding events on the result pipe. You have to call this |
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114 | regularly. Returns the number of events processed. Returns immediately |
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115 | when no events are outstanding. |
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116 | |
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117 | You can use Event to multiplex, e.g.: |
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118 | |
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119 | Event->io (fd => IO::AIO::poll_fileno, |
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120 | poll => 'r', async => 1, |
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121 | cb => \&IO::AIO::poll_cb); |
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122 | |
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123 | =item IO::AIO::poll_wait |
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124 | |
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125 | Wait till the result filehandle becomes ready for reading (simply does a |
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126 | select on the filehandle. This is useful if you want to synchronously wait |
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127 | for some requests to finish). |
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128 | |
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129 | See C<nreqs> for an example. |
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130 | |
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131 | =item IO::AIO::nreqs |
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132 | |
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133 | Returns the number of requests currently outstanding. |
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134 | |
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135 | Example: wait till there are no outstanding requests anymore: |
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136 | |
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137 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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138 | while IO::AIO::nreqs; |
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139 | |
94 | |
140 | =item aio_open $pathname, $flags, $mode, $callback |
95 | =item aio_open $pathname, $flags, $mode, $callback |
141 | |
96 | |
142 | Asynchronously open or create a file and call the callback with a newly |
97 | Asynchronously open or create a file and call the callback with a newly |
143 | created filehandle for the file. |
98 | created filehandle for the file. |
144 | |
99 | |
145 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
100 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
146 | for an explanation. |
101 | for an explanation. |
147 | |
102 | |
148 | The C<$mode> argument is a bitmask. See the C<Fcntl> module for a |
103 | The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
149 | list. They are the same as used in C<sysopen>. |
104 | list. They are the same as used by C<sysopen>. |
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105 | |
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106 | Likewise, C<$mode> specifies the mode of the newly created file, if it |
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107 | didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
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108 | except that it is mandatory (i.e. use C<0> if you don't create new files, |
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109 | and C<0666> or C<0777> if you do). |
150 | |
110 | |
151 | Example: |
111 | Example: |
152 | |
112 | |
153 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
113 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
154 | if ($_[0]) { |
114 | if ($_[0]) { |
… | |
… | |
161 | |
121 | |
162 | =item aio_close $fh, $callback |
122 | =item aio_close $fh, $callback |
163 | |
123 | |
164 | Asynchronously close a file and call the callback with the result |
124 | Asynchronously close a file and call the callback with the result |
165 | code. I<WARNING:> although accepted, you should not pass in a perl |
125 | code. I<WARNING:> although accepted, you should not pass in a perl |
166 | filehandle here, as perl will likely close the file descriptor itself when |
126 | filehandle here, as perl will likely close the file descriptor another |
167 | the filehandle is destroyed. Normally, you can safely call perls C<close> |
127 | time when the filehandle is destroyed. Normally, you can safely call perls |
168 | or just let filehandles go out of scope. |
128 | C<close> or just let filehandles go out of scope. |
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129 | |
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130 | This is supposed to be a bug in the API, so that might change. It's |
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131 | therefore best to avoid this function. |
169 | |
132 | |
170 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
133 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
171 | |
134 | |
172 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
135 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
173 | |
136 | |
174 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
137 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
175 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
138 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
176 | callback without the actual number of bytes read (or -1 on error, just |
139 | callback without the actual number of bytes read (or -1 on error, just |
177 | like the syscall). |
140 | like the syscall). |
178 | |
141 | |
179 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
142 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
180 | offset C<0> within the scalar: |
143 | offset C<0> within the scalar: |
181 | |
144 | |
182 | aio_read $fh, 7, 15, $buffer, 0, sub { |
145 | aio_read $fh, 7, 15, $buffer, 0, sub { |
183 | $_[0] >= 0 or die "read error: $!"; |
146 | $_[0] > 0 or die "read error: $!"; |
184 | print "read <$buffer>\n"; |
147 | print "read $_[0] bytes: <$buffer>\n"; |
185 | }; |
148 | }; |
186 | |
149 | |
187 | =item aio_readahead $fh,$offset,$length, $callback |
150 | =item aio_readahead $fh,$offset,$length, $callback |
188 | |
151 | |
189 | Asynchronously reads the specified byte range into the page cache, using |
152 | Asynchronously reads the specified byte range into the page cache, using |
190 | the C<readahead> syscall. If that syscall doesn't exist the status will be |
153 | the C<readahead> syscall. If that syscall doesn't exist (likely if your OS |
191 | C<-1> and C<$!> is set to ENOSYS. |
154 | isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>. |
192 | |
155 | |
193 | readahead() populates the page cache with data from a file so that |
156 | C<aio_readahead> populates the page cache with data from a file so that |
194 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
157 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
195 | argument specifies the starting point from which data is to be read and |
158 | argument specifies the starting point from which data is to be read and |
196 | C<$length> specifies the number of bytes to be read. I/O is performed in |
159 | C<$length> specifies the number of bytes to be read. I/O is performed in |
197 | whole pages, so that offset is effectively rounded down to a page boundary |
160 | whole pages, so that offset is effectively rounded down to a page boundary |
198 | and bytes are read up to the next page boundary greater than or equal to |
161 | and bytes are read up to the next page boundary greater than or equal to |
199 | (off-set+length). aio_readahead() does not read beyond the end of the |
162 | (off-set+length). C<aio_readahead> does not read beyond the end of the |
200 | file. The current file offset of the file is left unchanged. |
163 | file. The current file offset of the file is left unchanged. |
201 | |
164 | |
202 | =item aio_stat $fh_or_path, $callback |
165 | =item aio_stat $fh_or_path, $callback |
203 | |
166 | |
204 | =item aio_lstat $fh, $callback |
167 | =item aio_lstat $fh, $callback |
… | |
… | |
232 | with the fsync result code. |
195 | with the fsync result code. |
233 | |
196 | |
234 | =item aio_fdatasync $fh, $callback |
197 | =item aio_fdatasync $fh, $callback |
235 | |
198 | |
236 | Asynchronously call fdatasync on the given filehandle and call the |
199 | Asynchronously call fdatasync on the given filehandle and call the |
237 | callback with the fdatasync result code. |
200 | callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if |
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201 | C<fdatasync> is not available. |
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202 | |
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203 | =back |
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204 | |
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205 | =head2 SUPPORT FUNCTIONS |
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206 | |
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207 | =over 4 |
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208 | |
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209 | =item $fileno = IO::AIO::poll_fileno |
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210 | |
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211 | Return the I<request result pipe file descriptor>. This filehandle must be |
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212 | polled for reading by some mechanism outside this module (e.g. Event or |
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213 | select, see below or the SYNOPSIS). If the pipe becomes readable you have |
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214 | to call C<poll_cb> to check the results. |
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215 | |
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216 | See C<poll_cb> for an example. |
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217 | |
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218 | =item IO::AIO::poll_cb |
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219 | |
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220 | Process all outstanding events on the result pipe. You have to call this |
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221 | regularly. Returns the number of events processed. Returns immediately |
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222 | when no events are outstanding. |
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223 | |
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224 | Example: Install an Event watcher that automatically calls |
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225 | IO::AIO::poll_cb with high priority: |
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226 | |
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227 | Event->io (fd => IO::AIO::poll_fileno, |
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228 | poll => 'r', async => 1, |
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229 | cb => \&IO::AIO::poll_cb); |
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230 | |
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231 | =item IO::AIO::poll_wait |
|
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232 | |
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233 | Wait till the result filehandle becomes ready for reading (simply does a |
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234 | C<select> on the filehandle. This is useful if you want to synchronously wait |
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235 | for some requests to finish). |
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236 | |
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237 | See C<nreqs> for an example. |
|
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238 | |
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239 | =item IO::AIO::nreqs |
|
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240 | |
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241 | Returns the number of requests currently outstanding (i.e. for which their |
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242 | callback has not been invoked yet). |
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243 | |
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244 | Example: wait till there are no outstanding requests anymore: |
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245 | |
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246 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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247 | while IO::AIO::nreqs; |
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248 | |
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249 | =item IO::AIO::flush |
|
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250 | |
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251 | Wait till all outstanding AIO requests have been handled. |
|
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252 | |
|
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253 | Strictly equivalent to: |
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254 | |
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255 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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256 | while IO::AIO::nreqs; |
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257 | |
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258 | =item IO::AIO::poll |
|
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259 | |
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260 | Waits until some requests have been handled. |
|
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261 | |
|
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262 | Strictly equivalent to: |
|
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263 | |
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264 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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265 | if IO::AIO::nreqs; |
|
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266 | |
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267 | =item IO::AIO::min_parallel $nthreads |
|
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268 | |
|
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269 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
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270 | C<1>, which means a single asynchronous operation can be done at one time |
|
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271 | (the number of outstanding operations, however, is unlimited). |
|
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272 | |
|
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273 | It is recommended to keep the number of threads low, as some Linux |
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274 | kernel versions will scale negatively with the number of threads (higher |
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275 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
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276 | threads should be fine. |
|
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277 | |
|
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278 | Under normal circumstances you don't need to call this function, as this |
|
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279 | module automatically starts some threads (the exact number might change, |
|
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280 | and is currently 4). |
|
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281 | |
|
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282 | =item IO::AIO::max_parallel $nthreads |
|
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283 | |
|
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284 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
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285 | the specified number of threads are currently running, kill them. This |
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286 | function blocks until the limit is reached. |
|
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287 | |
|
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288 | This module automatically runs C<max_parallel 0> at program end, to ensure |
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289 | that all threads are killed and that there are no outstanding requests. |
|
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290 | |
|
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291 | Under normal circumstances you don't need to call this function. |
|
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292 | |
|
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293 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
|
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294 | |
|
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295 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
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296 | try to queue up more than this number of requests, the caller will block until |
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297 | some requests have been handled. |
|
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298 | |
|
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299 | The default is very large, so normally there is no practical limit. If you |
|
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300 | queue up many requests in a loop it it often improves speed if you set |
|
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301 | this to a relatively low number, such as C<100>. |
|
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302 | |
|
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303 | Under normal circumstances you don't need to call this function. |
|
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304 | |
|
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305 | =back |
238 | |
306 | |
239 | =cut |
307 | =cut |
240 | |
308 | |
241 | # support function to convert a fd into a perl filehandle |
309 | # support function to convert a fd into a perl filehandle |
242 | sub _fd2fh { |
310 | sub _fd2fh { |
… | |
… | |
256 | max_parallel 0; |
324 | max_parallel 0; |
257 | } |
325 | } |
258 | |
326 | |
259 | 1; |
327 | 1; |
260 | |
328 | |
261 | =back |
|
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262 | |
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263 | =head1 BUGS |
|
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264 | |
|
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265 | - could be optimized to use more semaphores instead of filehandles. |
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266 | |
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267 | =head1 SEE ALSO |
329 | =head1 SEE ALSO |
268 | |
330 | |
269 | L<Coro>, L<Linux::AIO>. |
331 | L<Coro>, L<Linux::AIO>. |
270 | |
332 | |
271 | =head1 AUTHOR |
333 | =head1 AUTHOR |