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Revision 1.6 by root, Mon Jul 11 03:29:39 2005 UTC vs.
Revision 1.10 by root, Wed Aug 17 05:26:20 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
102 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
103 error, just like the syscall). 121 error, just like the syscall).
104 122
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
105 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
106 offset 0 within the scalar: 128 offset 0 within the scalar:
107 129
108 aio_read $fh, 7, 15, $buffer, 0, sub { 130 aio_read $fh, 7, 15, $buffer, 0, sub {
109 $_[0] > 0 or die "read error: $!"; 131 $_[0] > 0 or die "read error: $!";
110 print "read $_[0] bytes: <$buffer>\n"; 132 print "read $_[0] bytes: <$buffer>\n";
111 }; 133 };
112 134
113 aio_readahead $fh,$offset,$length, $callback 135 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 136 "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 137 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 138 $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 139 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 140 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 141 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 142 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 143 read beyond the end of the file. The current file offset of the file
127 is left unchanged. 144 is left unchanged.
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.
128 149
129 aio_stat $fh_or_path, $callback 150 aio_stat $fh_or_path, $callback
130 aio_lstat $fh, $callback 151 aio_lstat $fh, $callback
131 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
132 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
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149 170
150 aio_unlink $pathname, $callback 171 aio_unlink $pathname, $callback
151 Asynchronously unlink (delete) a file and call the callback with the 172 Asynchronously unlink (delete) a file and call the callback with the
152 result code. 173 result code.
153 174
175 aio_rmdir $pathname, $callback
176 Asynchronously rmdir (delete) a directory and call the callback with
177 the result code.
178
154 aio_fsync $fh, $callback 179 aio_fsync $fh, $callback
155 Asynchronously call fsync on the given filehandle and call the 180 Asynchronously call fsync on the given filehandle and call the
156 callback with the fsync result code. 181 callback with the fsync result code.
157 182
158 aio_fdatasync $fh, $callback 183 aio_fdatasync $fh, $callback
159 Asynchronously call fdatasync on the given filehandle and call the 184 Asynchronously call fdatasync on the given filehandle and call the
160 callback with the fdatasync result code. 185 callback with the fdatasync result code.
161 186
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.
189
162 SUPPORT FUNCTIONS 190 SUPPORT FUNCTIONS
163 $fileno = IO::AIO::poll_fileno 191 $fileno = IO::AIO::poll_fileno
164 Return the *request result pipe filehandle*. This filehandle must be 192 Return the *request result pipe file descriptor*. This filehandle
165 polled for reading by some mechanism outside this module (e.g. Event 193 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 194 (e.g. Event or select, see below or the SYNOPSIS). If the pipe
167 "poll_cb" to check the results. 195 becomes readable you have to call "poll_cb" to check the results.
168 196
169 See "poll_cb" for an example. 197 See "poll_cb" for an example.
170 198
171 IO::AIO::poll_cb 199 IO::AIO::poll_cb
172 Process all outstanding events on the result pipe. You have to call 200 Process all outstanding events on the result pipe. You have to call
173 this regularly. Returns the number of events processed. Returns 201 this regularly. Returns the number of events processed. Returns
174 immediately when no events are outstanding. 202 immediately when no events are outstanding.
175 203
176 You can use Event to multiplex, e.g.: 204 Example: Install an Event watcher that automatically calls
205 IO::AIO::poll_cb with high priority:
177 206
178 Event->io (fd => IO::AIO::poll_fileno, 207 Event->io (fd => IO::AIO::poll_fileno,
179 poll => 'r', async => 1, 208 poll => 'r', async => 1,
180 cb => \&IO::AIO::poll_cb); 209 cb => \&IO::AIO::poll_cb);
181 210
182 IO::AIO::poll_wait 211 IO::AIO::poll_wait
183 Wait till the result filehandle becomes ready for reading (simply 212 Wait till the result filehandle becomes ready for reading (simply
184 does a select on the filehandle. This is useful if you want to 213 does a "select" on the filehandle. This is useful if you want to
185 synchronously wait for some requests to finish). 214 synchronously wait for some requests to finish).
186 215
187 See "nreqs" for an example. 216 See "nreqs" for an example.
188 217
189 IO::AIO::nreqs 218 IO::AIO::nreqs
190 Returns the number of requests currently outstanding. 219 Returns the number of requests currently outstanding (i.e. for which
220 their callback has not been invoked yet).
191 221
192 Example: wait till there are no outstanding requests anymore: 222 Example: wait till there are no outstanding requests anymore:
193 223
194 IO::AIO::poll_wait, IO::AIO::poll_cb 224 IO::AIO::poll_wait, IO::AIO::poll_cb
195 while IO::AIO::nreqs; 225 while IO::AIO::nreqs;
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244 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
245 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.
246 276
247 Under normal circumstances you don't need to call this function. 277 Under normal circumstances you don't need to call this function.
248 278
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
249SEE ALSO 287SEE ALSO
250 Coro, Linux::AIO. 288 Coro, Linux::AIO.
251 289
252AUTHOR 290AUTHOR
253 Marc Lehmann <schmorp@schmorp.de> 291 Marc Lehmann <schmorp@schmorp.de>

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