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Revision 1.5 by root, Sun Jul 10 23:45:16 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 \&IO::AIO::poll_cb; 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
31 # Danga::Socket
32 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
33 \&IO::AIO::poll_cb);
30 34
31DESCRIPTION 35DESCRIPTION
32 This module implements asynchronous I/O using whatever means your 36 This module implements asynchronous I/O using whatever means your
33 operating system supports. 37 operating system supports.
34 38
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41 currently, for example), and they would only support aio_read and 45 currently, for example), and they would only support aio_read and
42 aio_write, so the remaining functionality would have to be implemented 46 aio_write, so the remaining functionality would have to be implemented
43 using threads anyway. 47 using threads anyway.
44 48
45 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
46 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.
47 53
48FUNCTIONS 54FUNCTIONS
49 AIO FUNCTIONS 55 AIO FUNCTIONS
50 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
51 with the same name (sans "aio_"). The arguments are similar or 57 with the same name (sans "aio_"). The arguments are similar or
52 identical, and they all accept an additional $callback argument which 58 identical, and they all accept an additional (and optional) $callback
53 must be a code reference. This code reference will get called with the 59 argument which must be a code reference. This code reference will get
54 syscall return code (e.g. most syscalls return -1 on error, unlike perl, 60 called with the syscall return code (e.g. most syscalls return -1 on
55 which usually delivers "false") as it's sole argument when the given 61 error, unlike perl, which usually delivers "false") as it's sole
56 syscall has been executed asynchronously. 62 argument when the given syscall has been executed asynchronously.
57 63
58 All functions that expect a filehandle will also accept a file 64 All functions expecting a filehandle keep a copy of the filehandle
59 descriptor. 65 internally until the request has finished.
60 66
61 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
62 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
63 directory could have changed. Alternatively, you can make sure that you 69 is being executed, the current working directory could have changed.
64 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.
65 79
66 aio_open $pathname, $flags, $mode, $callback 80 aio_open $pathname, $flags, $mode, $callback
67 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
68 newly created filehandle for the file. 82 newly created filehandle for the file.
69 83
70 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,
71 above, for an explanation. 85 above, for an explanation.
72 86
73 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.
74 They are the same as used in "sysopen". 88 They are the same as used by "sysopen".
89
90 Likewise, $mode specifies the mode of the newly created file, if it
91 didn't exist and "O_CREAT" has been given, just like perl's
92 "sysopen", except that it is mandatory (i.e. use 0 if you don't
93 create new files, and 0666 or 0777 if you do).
75 94
76 Example: 95 Example:
77 96
78 aio_open "/etc/passwd", O_RDONLY, 0, sub { 97 aio_open "/etc/passwd", O_RDONLY, 0, sub {
79 if ($_[0]) { 98 if ($_[0]) {
… …
86 105
87 aio_close $fh, $callback 106 aio_close $fh, $callback
88 Asynchronously close a file and call the callback with the result 107 Asynchronously close a file and call the callback with the result
89 code. *WARNING:* although accepted, you should not pass in a perl 108 code. *WARNING:* although accepted, you should not pass in a perl
90 filehandle here, as perl will likely close the file descriptor 109 filehandle here, as perl will likely close the file descriptor
91 itself when the filehandle is destroyed. Normally, you can safely 110 another time when the filehandle is destroyed. Normally, you can
92 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.
93 115
94 aio_read $fh,$offset,$length, $data,$dataoffset,$callback 116 aio_read $fh,$offset,$length, $data,$dataoffset,$callback
95 aio_write $fh,$offset,$length, $data,$dataoffset,$callback 117 aio_write $fh,$offset,$length, $data,$dataoffset,$callback
96 Reads or writes "length" bytes from the specified "fh" and "offset" 118 Reads or writes "length" bytes from the specified "fh" and "offset"
97 into the scalar given by "data" and offset "dataoffset" and calls 119 into the scalar given by "data" and offset "dataoffset" and calls
98 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
99 error, just like the syscall). 121 error, just like the syscall).
100 122
101 Example: Read 15 bytes at offset 7 into scalar $buffer, strating at 123 Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
102 offset 0 within the scalar: 124 offset 0 within the scalar:
103 125
104 aio_read $fh, 7, 15, $buffer, 0, sub { 126 aio_read $fh, 7, 15, $buffer, 0, sub {
105 $_[0] > 0 or die "read error: $!"; 127 $_[0] > 0 or die "read error: $!";
106 print "read $_[0] bytes: <$buffer>\n"; 128 print "read $_[0] bytes: <$buffer>\n";
107 }; 129 };
108 130
109 aio_readahead $fh,$offset,$length, $callback 131 aio_readahead $fh,$offset,$length, $callback
110 Asynchronously reads the specified byte range into the page cache,
111 using the "readahead" syscall. If that syscall doesn't exist the
112 status will be -1 and $! is set to ENOSYS.
113
114 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
115 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
116 $offset argument specifies the starting point from which data is to 134 $offset argument specifies the starting point from which data is to
117 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
118 performed in whole pages, so that offset is effectively rounded down 136 performed in whole pages, so that offset is effectively rounded down
119 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
120 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
121 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
122 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.
123 145
124 aio_stat $fh_or_path, $callback 146 aio_stat $fh_or_path, $callback
125 aio_lstat $fh, $callback 147 aio_lstat $fh, $callback
126 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
127 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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144 166
145 aio_unlink $pathname, $callback 167 aio_unlink $pathname, $callback
146 Asynchronously unlink (delete) a file and call the callback with the 168 Asynchronously unlink (delete) a file and call the callback with the
147 result code. 169 result code.
148 170
171 aio_rmdir $pathname, $callback
172 Asynchronously rmdir (delete) a directory and call the callback with
173 the result code.
174
149 aio_fsync $fh, $callback 175 aio_fsync $fh, $callback
150 Asynchronously call fsync on the given filehandle and call the 176 Asynchronously call fsync on the given filehandle and call the
151 callback with the fsync result code. 177 callback with the fsync result code.
152 178
153 aio_fdatasync $fh, $callback 179 aio_fdatasync $fh, $callback
154 Asynchronously call fdatasync on the given filehandle and call the 180 Asynchronously call fdatasync on the given filehandle and call the
155 callback with the fdatasync result code. 181 callback with the fdatasync result code.
156 182
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
157 SUPPORT FUNCTIONS 186 SUPPORT FUNCTIONS
158 $fileno = IO::AIO::poll_fileno 187 $fileno = IO::AIO::poll_fileno
159 Return the *request result pipe filehandle*. This filehandle must be 188 Return the *request result pipe file descriptor*. This filehandle
160 polled for reading by some mechanism outside this module (e.g. Event 189 must be polled for reading by some mechanism outside this module
161 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
162 "poll_cb" to check the results. 191 becomes readable you have to call "poll_cb" to check the results.
163 192
164 See "poll_cb" for an example. 193 See "poll_cb" for an example.
165 194
166 IO::AIO::poll_cb 195 IO::AIO::poll_cb
167 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
168 this regularly. Returns the number of events processed. Returns 197 this regularly. Returns the number of events processed. Returns
169 immediately when no events are outstanding. 198 immediately when no events are outstanding.
170 199
171 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:
172 202
173 Event->io (fd => IO::AIO::poll_fileno, 203 Event->io (fd => IO::AIO::poll_fileno,
174 poll => 'r', async => 1, 204 poll => 'r', async => 1,
175 cb => \&IO::AIO::poll_cb); 205 cb => \&IO::AIO::poll_cb);
176 206
177 IO::AIO::poll_wait 207 IO::AIO::poll_wait
178 Wait till the result filehandle becomes ready for reading (simply 208 Wait till the result filehandle becomes ready for reading (simply
179 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
180 synchronously wait for some requests to finish). 210 synchronously wait for some requests to finish).
181 211
182 See "nreqs" for an example. 212 See "nreqs" for an example.
183 213
184 IO::AIO::nreqs 214 IO::AIO::nreqs
185 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).
186 217
187 Example: wait till there are no outstanding requests anymore: 218 Example: wait till there are no outstanding requests anymore:
188 219
189 IO::AIO::poll_wait, IO::AIO::poll_cb 220 IO::AIO::poll_wait, IO::AIO::poll_cb
190 while IO::AIO::nreqs; 221 while IO::AIO::nreqs;
222
223 IO::AIO::flush
224 Wait till all outstanding AIO requests have been handled.
225
226 Strictly equivalent to:
227
228 IO::AIO::poll_wait, IO::AIO::poll_cb
229 while IO::AIO::nreqs;
230
231 IO::AIO::poll
232 Waits until some requests have been handled.
233
234 Strictly equivalent to:
235
236 IO::AIO::poll_wait, IO::AIO::poll_cb
237 if IO::AIO::nreqs;
191 238
192 IO::AIO::min_parallel $nthreads 239 IO::AIO::min_parallel $nthreads
193 Set the minimum number of AIO threads to $nthreads. The default is 240 Set the minimum number of AIO threads to $nthreads. The default is
194 1, which means a single asynchronous operation can be done at one 241 1, which means a single asynchronous operation can be done at one
195 time (the number of outstanding operations, however, is unlimited). 242 time (the number of outstanding operations, however, is unlimited).
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223 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
224 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.
225 272
226 Under normal circumstances you don't need to call this function. 273 Under normal circumstances you don't need to call this function.
227 274
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
228SEE ALSO 280SEE ALSO
229 Coro, Linux::AIO. 281 Coro, Linux::AIO.
230 282
231AUTHOR 283AUTHOR
232 Marc Lehmann <schmorp@schmorp.de> 284 Marc Lehmann <schmorp@schmorp.de>

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