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Revision 1.8 by root, Sun Jul 31 17:24:05 2005 UTC vs.
Revision 1.10 by root, Wed Aug 17 05:26:20 2005 UTC

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62 argument when the given syscall has been executed asynchronously. 62 argument when the given syscall has been executed asynchronously.
63 63
64 All functions expecting a filehandle keep a copy of the filehandle 64 All functions expecting a filehandle keep a copy of the filehandle
65 internally until the request has finished. 65 internally until the request has finished.
66 66
67 The filenames you pass to these routines *must* be absolute. The reason 67 The pathnames you pass to these routines *must* be absolute and encoded
68 for this is that at the time the request is being executed, the current 68 in byte form. The reason for the former is that at the time the request
69 working directory could have changed. Alternatively, you can make sure 69 is being executed, the current working directory could have changed.
70 that you never change the current working directory. 70 Alternatively, you can make sure that you never change the current
71 working directory.
72
73 To encode pathnames to byte form, either make sure you either: a) always
74 pass in filenames you got from outside (command line, readdir etc.), b)
75 are ASCII or ISO 8859-1, c) use the Encode module and encode your
76 pathnames to the locale (or other) encoding in effect in the user
77 environment, d) use Glib::filename_from_unicode on unicode filenames or
78 e) use something else.
71 79
72 aio_open $pathname, $flags, $mode, $callback 80 aio_open $pathname, $flags, $mode, $callback
73 Asynchronously open or create a file and call the callback with a 81 Asynchronously open or create a file and call the callback with a
74 newly created filehandle for the file. 82 newly created filehandle for the file.
75 83
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110 Reads or writes "length" bytes from the specified "fh" and "offset" 118 Reads or writes "length" bytes from the specified "fh" and "offset"
111 into the scalar given by "data" and offset "dataoffset" and calls 119 into the scalar given by "data" and offset "dataoffset" and calls
112 the callback without the actual number of bytes read (or -1 on 120 the callback without the actual number of bytes read (or -1 on
113 error, just like the syscall). 121 error, just like the syscall).
114 122
123 The $data scalar *MUST NOT* be modified in any way while the request
124 is outstanding. Modifying it can result in segfaults or WW3 (if the
125 necessary/optional hardware is installed).
126
115 Example: Read 15 bytes at offset 7 into scalar $buffer, starting at 127 Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
116 offset 0 within the scalar: 128 offset 0 within the scalar:
117 129
118 aio_read $fh, 7, 15, $buffer, 0, sub { 130 aio_read $fh, 7, 15, $buffer, 0, sub {
119 $_[0] > 0 or die "read error: $!"; 131 $_[0] > 0 or die "read error: $!";
120 print "read $_[0] bytes: <$buffer>\n"; 132 print "read $_[0] bytes: <$buffer>\n";
121 }; 133 };
122 134
123 aio_readahead $fh,$offset,$length, $callback 135 aio_readahead $fh,$offset,$length, $callback
124 Asynchronously reads the specified byte range into the page cache,
125 using the "readahead" syscall. If that syscall doesn't exist (likely
126 if your OS isn't Linux) the status will be -1 and $! is set to
127 "ENOSYS".
128
129 "aio_readahead" populates the page cache with data from a file so 136 "aio_readahead" populates the page cache with data from a file so
130 that subsequent reads from that file will not block on disk I/O. The 137 that subsequent reads from that file will not block on disk I/O. The
131 $offset argument specifies the starting point from which data is to 138 $offset argument specifies the starting point from which data is to
132 be read and $length specifies the number of bytes to be read. I/O is 139 be read and $length specifies the number of bytes to be read. I/O is
133 performed in whole pages, so that offset is effectively rounded down 140 performed in whole pages, so that offset is effectively rounded down
134 to a page boundary and bytes are read up to the next page boundary 141 to a page boundary and bytes are read up to the next page boundary
135 greater than or equal to (off-set+length). "aio_readahead" does not 142 greater than or equal to (off-set+length). "aio_readahead" does not
136 read beyond the end of the file. The current file offset of the file 143 read beyond the end of the file. The current file offset of the file
137 is left unchanged. 144 is left unchanged.
138 145
146 If that syscall doesn't exist (likely if your OS isn't Linux) it
147 will be emulated by simply reading the data, which would have a
148 similar effect.
149
139 aio_stat $fh_or_path, $callback 150 aio_stat $fh_or_path, $callback
140 aio_lstat $fh, $callback 151 aio_lstat $fh, $callback
141 Works like perl's "stat" or "lstat" in void context. The callback 152 Works like perl's "stat" or "lstat" in void context. The callback
142 will be called after the stat and the results will be available 153 will be called after the stat and the results will be available
143 using "stat _" or "-s _" etc... 154 using "stat _" or "-s _" etc...
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159 170
160 aio_unlink $pathname, $callback 171 aio_unlink $pathname, $callback
161 Asynchronously unlink (delete) a file and call the callback with the 172 Asynchronously unlink (delete) a file and call the callback with the
162 result code. 173 result code.
163 174
175 aio_rmdir $pathname, $callback
176 Asynchronously rmdir (delete) a directory and call the callback with
177 the result code.
178
164 aio_fsync $fh, $callback 179 aio_fsync $fh, $callback
165 Asynchronously call fsync on the given filehandle and call the 180 Asynchronously call fsync on the given filehandle and call the
166 callback with the fsync result code. 181 callback with the fsync result code.
167 182
168 aio_fdatasync $fh, $callback 183 aio_fdatasync $fh, $callback
169 Asynchronously call fdatasync on the given filehandle and call the 184 Asynchronously call fdatasync on the given filehandle and call the
170 callback with the fdatasync result code. Might set $! to "ENOSYS" if 185 callback with the fdatasync result code.
171 "fdatasync" is not available. 186
187 If this call isn't available because your OS lacks it or it couldn't
188 be detected, it will be emulated by calling "fsync" instead.
172 189
173 SUPPORT FUNCTIONS 190 SUPPORT FUNCTIONS
174 $fileno = IO::AIO::poll_fileno 191 $fileno = IO::AIO::poll_fileno
175 Return the *request result pipe file descriptor*. This filehandle 192 Return the *request result pipe file descriptor*. This filehandle
176 must be polled for reading by some mechanism outside this module 193 must be polled for reading by some mechanism outside this module
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257 If you queue up many requests in a loop it it often improves speed 274 If you queue up many requests in a loop it it often improves speed
258 if you set this to a relatively low number, such as 100. 275 if you set this to a relatively low number, such as 100.
259 276
260 Under normal circumstances you don't need to call this function. 277 Under normal circumstances you don't need to call this function.
261 278
279 FORK BEHAVIOUR
280 Before the fork IO::AIO enters a quiescent state where no requests can
281 be added in other threads and no results will be processed. After the
282 fork the parent simply leaves the quiescent state and continues
283 request/result processing, while the child clears the request/result
284 queue and starts the same number of threads as were in use by the
285 parent.
286
262SEE ALSO 287SEE ALSO
263 Coro, Linux::AIO. 288 Coro, Linux::AIO.
264 289
265AUTHOR 290AUTHOR
266 Marc Lehmann <schmorp@schmorp.de> 291 Marc Lehmann <schmorp@schmorp.de>

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