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Revision 1.6 by root, Mon Jul 11 03:29:39 2005 UTC vs.
Revision 1.9 by root, Tue Aug 16 23:33:38 2005 UTC

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20 poll => 'r', 20 poll => 'r',
21 cb => \&IO::AIO::poll_cb); 21 cb => \&IO::AIO::poll_cb);
22 22
23 # Glib/Gtk2 23 # Glib/Gtk2
24 add_watch Glib::IO IO::AIO::poll_fileno, 24 add_watch Glib::IO IO::AIO::poll_fileno,
25 in => sub { IO::AIO::poll_cb, 1 }; 25 in => sub { IO::AIO::poll_cb; 1 };
26 26
27 # Tk 27 # Tk
28 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", 28 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
29 readable => \&IO::AIO::poll_cb); 29 readable => \&IO::AIO::poll_cb);
30 30
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45 currently, for example), and they would only support aio_read and 45 currently, for example), and they would only support aio_read and
46 aio_write, so the remaining functionality would have to be implemented 46 aio_write, so the remaining functionality would have to be implemented
47 using threads anyway. 47 using threads anyway.
48 48
49 Although the module will work with in the presence of other threads, it 49 Although the module will work with in the presence of other threads, it
50 is currently not reentrant, so use appropriate locking yourself. 50 is currently not reentrant, so use appropriate locking yourself, always
51 call "poll_cb" from within the same thread, or never call "poll_cb" (or
52 other "aio_" functions) recursively.
51 53
52FUNCTIONS 54FUNCTIONS
53 AIO FUNCTIONS 55 AIO FUNCTIONS
54 All the "aio_*" calls are more or less thin wrappers around the syscall 56 All the "aio_*" calls are more or less thin wrappers around the syscall
55 with the same name (sans "aio_"). The arguments are similar or 57 with the same name (sans "aio_"). The arguments are similar or
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57 argument which must be a code reference. This code reference will get 59 argument which must be a code reference. This code reference will get
58 called with the syscall return code (e.g. most syscalls return -1 on 60 called with the syscall return code (e.g. most syscalls return -1 on
59 error, unlike perl, which usually delivers "false") as it's sole 61 error, unlike perl, which usually delivers "false") as it's sole
60 argument when the given syscall has been executed asynchronously. 62 argument when the given syscall has been executed asynchronously.
61 63
62 All functions that expect a filehandle will also accept a file 64 All functions expecting a filehandle keep a copy of the filehandle
63 descriptor. 65 internally until the request has finished.
64 66
65 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
66 is that at the time the request is being executed, the current working 68 in byte form. The reason for the former is that at the time the request
67 directory could have changed. Alternatively, you can make sure that you 69 is being executed, the current working directory could have changed.
68 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.
69 79
70 aio_open $pathname, $flags, $mode, $callback 80 aio_open $pathname, $flags, $mode, $callback
71 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
72 newly created filehandle for the file. 82 newly created filehandle for the file.
73 83
74 The pathname passed to "aio_open" must be absolute. See API NOTES, 84 The pathname passed to "aio_open" must be absolute. See API NOTES,
75 above, for an explanation. 85 above, for an explanation.
76 86
77 The $mode argument is a bitmask. See the "Fcntl" module for a list. 87 The $flags argument is a bitmask. See the "Fcntl" module for a list.
78 They are the same as used in "sysopen". 88 They are the same as used by "sysopen".
89
90 Likewise, $mode specifies the mode of the newly created file, if it
91 didn't exist and "O_CREAT" has been given, just like perl's
92 "sysopen", except that it is mandatory (i.e. use 0 if you don't
93 create new files, and 0666 or 0777 if you do).
79 94
80 Example: 95 Example:
81 96
82 aio_open "/etc/passwd", O_RDONLY, 0, sub { 97 aio_open "/etc/passwd", O_RDONLY, 0, sub {
83 if ($_[0]) { 98 if ($_[0]) {
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90 105
91 aio_close $fh, $callback 106 aio_close $fh, $callback
92 Asynchronously close a file and call the callback with the result 107 Asynchronously close a file and call the callback with the result
93 code. *WARNING:* although accepted, you should not pass in a perl 108 code. *WARNING:* although accepted, you should not pass in a perl
94 filehandle here, as perl will likely close the file descriptor 109 filehandle here, as perl will likely close the file descriptor
95 itself when the filehandle is destroyed. Normally, you can safely 110 another time when the filehandle is destroyed. Normally, you can
96 call perls "close" or just let filehandles go out of scope. 111 safely call perls "close" or just let filehandles go out of scope.
112
113 This is supposed to be a bug in the API, so that might change. It's
114 therefore best to avoid this function.
97 115
98 aio_read $fh,$offset,$length, $data,$dataoffset,$callback 116 aio_read $fh,$offset,$length, $data,$dataoffset,$callback
99 aio_write $fh,$offset,$length, $data,$dataoffset,$callback 117 aio_write $fh,$offset,$length, $data,$dataoffset,$callback
100 Reads or writes "length" bytes from the specified "fh" and "offset" 118 Reads or writes "length" bytes from the specified "fh" and "offset"
101 into the scalar given by "data" and offset "dataoffset" and calls 119 into the scalar given by "data" and offset "dataoffset" and calls
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109 $_[0] > 0 or die "read error: $!"; 127 $_[0] > 0 or die "read error: $!";
110 print "read $_[0] bytes: <$buffer>\n"; 128 print "read $_[0] bytes: <$buffer>\n";
111 }; 129 };
112 130
113 aio_readahead $fh,$offset,$length, $callback 131 aio_readahead $fh,$offset,$length, $callback
114 Asynchronously reads the specified byte range into the page cache,
115 using the "readahead" syscall. If that syscall doesn't exist (likely
116 if your OS isn't Linux) the status will be -1 and $! is set to
117 ENOSYS.
118
119 readahead() populates the page cache with data from a file so that 132 "aio_readahead" populates the page cache with data from a file so
120 subsequent reads from that file will not block on disk I/O. The 133 that subsequent reads from that file will not block on disk I/O. The
121 $offset argument specifies the starting point from which data is to 134 $offset argument specifies the starting point from which data is to
122 be read and $length specifies the number of bytes to be read. I/O is 135 be read and $length specifies the number of bytes to be read. I/O is
123 performed in whole pages, so that offset is effectively rounded down 136 performed in whole pages, so that offset is effectively rounded down
124 to a page boundary and bytes are read up to the next page boundary 137 to a page boundary and bytes are read up to the next page boundary
125 greater than or equal to (off-set+length). aio_readahead() does not 138 greater than or equal to (off-set+length). "aio_readahead" does not
126 read beyond the end of the file. The current file offset of the file 139 read beyond the end of the file. The current file offset of the file
127 is left unchanged. 140 is left unchanged.
141
142 If that syscall doesn't exist (likely if your OS isn't Linux) it
143 will be emulated by simply reading the data, which would have a
144 similar effect.
128 145
129 aio_stat $fh_or_path, $callback 146 aio_stat $fh_or_path, $callback
130 aio_lstat $fh, $callback 147 aio_lstat $fh, $callback
131 Works like perl's "stat" or "lstat" in void context. The callback 148 Works like perl's "stat" or "lstat" in void context. The callback
132 will be called after the stat and the results will be available 149 will be called after the stat and the results will be available
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149 166
150 aio_unlink $pathname, $callback 167 aio_unlink $pathname, $callback
151 Asynchronously unlink (delete) a file and call the callback with the 168 Asynchronously unlink (delete) a file and call the callback with the
152 result code. 169 result code.
153 170
171 aio_rmdir $pathname, $callback
172 Asynchronously rmdir (delete) a directory and call the callback with
173 the result code.
174
154 aio_fsync $fh, $callback 175 aio_fsync $fh, $callback
155 Asynchronously call fsync on the given filehandle and call the 176 Asynchronously call fsync on the given filehandle and call the
156 callback with the fsync result code. 177 callback with the fsync result code.
157 178
158 aio_fdatasync $fh, $callback 179 aio_fdatasync $fh, $callback
159 Asynchronously call fdatasync on the given filehandle and call the 180 Asynchronously call fdatasync on the given filehandle and call the
160 callback with the fdatasync result code. 181 callback with the fdatasync result code.
161 182
183 If this call isn't available because your OS lacks it or it couldn't
184 be detected, it will be emulated by calling "fsync" instead.
185
162 SUPPORT FUNCTIONS 186 SUPPORT FUNCTIONS
163 $fileno = IO::AIO::poll_fileno 187 $fileno = IO::AIO::poll_fileno
164 Return the *request result pipe filehandle*. This filehandle must be 188 Return the *request result pipe file descriptor*. This filehandle
165 polled for reading by some mechanism outside this module (e.g. Event 189 must be polled for reading by some mechanism outside this module
166 or select, see below). If the pipe becomes readable you have to call 190 (e.g. Event or select, see below or the SYNOPSIS). If the pipe
167 "poll_cb" to check the results. 191 becomes readable you have to call "poll_cb" to check the results.
168 192
169 See "poll_cb" for an example. 193 See "poll_cb" for an example.
170 194
171 IO::AIO::poll_cb 195 IO::AIO::poll_cb
172 Process all outstanding events on the result pipe. You have to call 196 Process all outstanding events on the result pipe. You have to call
173 this regularly. Returns the number of events processed. Returns 197 this regularly. Returns the number of events processed. Returns
174 immediately when no events are outstanding. 198 immediately when no events are outstanding.
175 199
176 You can use Event to multiplex, e.g.: 200 Example: Install an Event watcher that automatically calls
201 IO::AIO::poll_cb with high priority:
177 202
178 Event->io (fd => IO::AIO::poll_fileno, 203 Event->io (fd => IO::AIO::poll_fileno,
179 poll => 'r', async => 1, 204 poll => 'r', async => 1,
180 cb => \&IO::AIO::poll_cb); 205 cb => \&IO::AIO::poll_cb);
181 206
182 IO::AIO::poll_wait 207 IO::AIO::poll_wait
183 Wait till the result filehandle becomes ready for reading (simply 208 Wait till the result filehandle becomes ready for reading (simply
184 does a select on the filehandle. This is useful if you want to 209 does a "select" on the filehandle. This is useful if you want to
185 synchronously wait for some requests to finish). 210 synchronously wait for some requests to finish).
186 211
187 See "nreqs" for an example. 212 See "nreqs" for an example.
188 213
189 IO::AIO::nreqs 214 IO::AIO::nreqs
190 Returns the number of requests currently outstanding. 215 Returns the number of requests currently outstanding (i.e. for which
216 their callback has not been invoked yet).
191 217
192 Example: wait till there are no outstanding requests anymore: 218 Example: wait till there are no outstanding requests anymore:
193 219
194 IO::AIO::poll_wait, IO::AIO::poll_cb 220 IO::AIO::poll_wait, IO::AIO::poll_cb
195 while IO::AIO::nreqs; 221 while IO::AIO::nreqs;
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244 If you queue up many requests in a loop it it often improves speed 270 If you queue up many requests in a loop it it often improves speed
245 if you set this to a relatively low number, such as 100. 271 if you set this to a relatively low number, such as 100.
246 272
247 Under normal circumstances you don't need to call this function. 273 Under normal circumstances you don't need to call this function.
248 274
275 FORK BEHAVIOUR
276 IO::AIO handles all outstanding AIO requests before the fork, destroys
277 all AIO threads, and recreates them in both the parent and the child
278 after the fork.
279
249SEE ALSO 280SEE ALSO
250 Coro, Linux::AIO. 281 Coro, Linux::AIO.
251 282
252AUTHOR 283AUTHOR
253 Marc Lehmann <schmorp@schmorp.de> 284 Marc Lehmann <schmorp@schmorp.de>

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