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Revision 1.5 by root, Sun Jul 10 23:45:16 2005 UTC vs.
Revision 1.8 by root, Sun Jul 31 17:24:05 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 filenames you pass to these routines *must* be absolute. The reason
62 is that at the time the request is being executed, the current working 68 for this is that at the time the request is being executed, the current
63 directory could have changed. Alternatively, you can make sure that you 69 working directory could have changed. Alternatively, you can make sure
64 never change the current working directory. 70 that you never change the current working directory.
65 71
66 aio_open $pathname, $flags, $mode, $callback 72 aio_open $pathname, $flags, $mode, $callback
67 Asynchronously open or create a file and call the callback with a 73 Asynchronously open or create a file and call the callback with a
68 newly created filehandle for the file. 74 newly created filehandle for the file.
69 75
70 The pathname passed to "aio_open" must be absolute. See API NOTES, 76 The pathname passed to "aio_open" must be absolute. See API NOTES,
71 above, for an explanation. 77 above, for an explanation.
72 78
73 The $mode argument is a bitmask. See the "Fcntl" module for a list. 79 The $flags argument is a bitmask. See the "Fcntl" module for a list.
74 They are the same as used in "sysopen". 80 They are the same as used by "sysopen".
81
82 Likewise, $mode specifies the mode of the newly created file, if it
83 didn't exist and "O_CREAT" has been given, just like perl's
84 "sysopen", except that it is mandatory (i.e. use 0 if you don't
85 create new files, and 0666 or 0777 if you do).
75 86
76 Example: 87 Example:
77 88
78 aio_open "/etc/passwd", O_RDONLY, 0, sub { 89 aio_open "/etc/passwd", O_RDONLY, 0, sub {
79 if ($_[0]) { 90 if ($_[0]) {
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86 97
87 aio_close $fh, $callback 98 aio_close $fh, $callback
88 Asynchronously close a file and call the callback with the result 99 Asynchronously close a file and call the callback with the result
89 code. *WARNING:* although accepted, you should not pass in a perl 100 code. *WARNING:* although accepted, you should not pass in a perl
90 filehandle here, as perl will likely close the file descriptor 101 filehandle here, as perl will likely close the file descriptor
91 itself when the filehandle is destroyed. Normally, you can safely 102 another time when the filehandle is destroyed. Normally, you can
92 call perls "close" or just let filehandles go out of scope. 103 safely call perls "close" or just let filehandles go out of scope.
104
105 This is supposed to be a bug in the API, so that might change. It's
106 therefore best to avoid this function.
93 107
94 aio_read $fh,$offset,$length, $data,$dataoffset,$callback 108 aio_read $fh,$offset,$length, $data,$dataoffset,$callback
95 aio_write $fh,$offset,$length, $data,$dataoffset,$callback 109 aio_write $fh,$offset,$length, $data,$dataoffset,$callback
96 Reads or writes "length" bytes from the specified "fh" and "offset" 110 Reads or writes "length" bytes from the specified "fh" and "offset"
97 into the scalar given by "data" and offset "dataoffset" and calls 111 into the scalar given by "data" and offset "dataoffset" and calls
98 the callback without the actual number of bytes read (or -1 on 112 the callback without the actual number of bytes read (or -1 on
99 error, just like the syscall). 113 error, just like the syscall).
100 114
101 Example: Read 15 bytes at offset 7 into scalar $buffer, strating at 115 Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
102 offset 0 within the scalar: 116 offset 0 within the scalar:
103 117
104 aio_read $fh, 7, 15, $buffer, 0, sub { 118 aio_read $fh, 7, 15, $buffer, 0, sub {
105 $_[0] > 0 or die "read error: $!"; 119 $_[0] > 0 or die "read error: $!";
106 print "read $_[0] bytes: <$buffer>\n"; 120 print "read $_[0] bytes: <$buffer>\n";
107 }; 121 };
108 122
109 aio_readahead $fh,$offset,$length, $callback 123 aio_readahead $fh,$offset,$length, $callback
110 Asynchronously reads the specified byte range into the page cache, 124 Asynchronously reads the specified byte range into the page cache,
111 using the "readahead" syscall. If that syscall doesn't exist the 125 using the "readahead" syscall. If that syscall doesn't exist (likely
112 status will be -1 and $! is set to ENOSYS. 126 if your OS isn't Linux) the status will be -1 and $! is set to
127 "ENOSYS".
113 128
114 readahead() populates the page cache with data from a file so that 129 "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 130 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 131 $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 132 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 133 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 134 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 135 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 136 read beyond the end of the file. The current file offset of the file
122 is left unchanged. 137 is left unchanged.
123 138
124 aio_stat $fh_or_path, $callback 139 aio_stat $fh_or_path, $callback
125 aio_lstat $fh, $callback 140 aio_lstat $fh, $callback
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150 Asynchronously call fsync on the given filehandle and call the 165 Asynchronously call fsync on the given filehandle and call the
151 callback with the fsync result code. 166 callback with the fsync result code.
152 167
153 aio_fdatasync $fh, $callback 168 aio_fdatasync $fh, $callback
154 Asynchronously call fdatasync on the given filehandle and call the 169 Asynchronously call fdatasync on the given filehandle and call the
155 callback with the fdatasync result code. 170 callback with the fdatasync result code. Might set $! to "ENOSYS" if
171 "fdatasync" is not available.
156 172
157 SUPPORT FUNCTIONS 173 SUPPORT FUNCTIONS
158 $fileno = IO::AIO::poll_fileno 174 $fileno = IO::AIO::poll_fileno
159 Return the *request result pipe filehandle*. This filehandle must be 175 Return the *request result pipe file descriptor*. This filehandle
160 polled for reading by some mechanism outside this module (e.g. Event 176 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 177 (e.g. Event or select, see below or the SYNOPSIS). If the pipe
162 "poll_cb" to check the results. 178 becomes readable you have to call "poll_cb" to check the results.
163 179
164 See "poll_cb" for an example. 180 See "poll_cb" for an example.
165 181
166 IO::AIO::poll_cb 182 IO::AIO::poll_cb
167 Process all outstanding events on the result pipe. You have to call 183 Process all outstanding events on the result pipe. You have to call
168 this regularly. Returns the number of events processed. Returns 184 this regularly. Returns the number of events processed. Returns
169 immediately when no events are outstanding. 185 immediately when no events are outstanding.
170 186
171 You can use Event to multiplex, e.g.: 187 Example: Install an Event watcher that automatically calls
188 IO::AIO::poll_cb with high priority:
172 189
173 Event->io (fd => IO::AIO::poll_fileno, 190 Event->io (fd => IO::AIO::poll_fileno,
174 poll => 'r', async => 1, 191 poll => 'r', async => 1,
175 cb => \&IO::AIO::poll_cb); 192 cb => \&IO::AIO::poll_cb);
176 193
177 IO::AIO::poll_wait 194 IO::AIO::poll_wait
178 Wait till the result filehandle becomes ready for reading (simply 195 Wait till the result filehandle becomes ready for reading (simply
179 does a select on the filehandle. This is useful if you want to 196 does a "select" on the filehandle. This is useful if you want to
180 synchronously wait for some requests to finish). 197 synchronously wait for some requests to finish).
181 198
182 See "nreqs" for an example. 199 See "nreqs" for an example.
183 200
184 IO::AIO::nreqs 201 IO::AIO::nreqs
185 Returns the number of requests currently outstanding. 202 Returns the number of requests currently outstanding (i.e. for which
203 their callback has not been invoked yet).
186 204
187 Example: wait till there are no outstanding requests anymore: 205 Example: wait till there are no outstanding requests anymore:
188 206
189 IO::AIO::poll_wait, IO::AIO::poll_cb 207 IO::AIO::poll_wait, IO::AIO::poll_cb
190 while IO::AIO::nreqs; 208 while IO::AIO::nreqs;
209
210 IO::AIO::flush
211 Wait till all outstanding AIO requests have been handled.
212
213 Strictly equivalent to:
214
215 IO::AIO::poll_wait, IO::AIO::poll_cb
216 while IO::AIO::nreqs;
217
218 IO::AIO::poll
219 Waits until some requests have been handled.
220
221 Strictly equivalent to:
222
223 IO::AIO::poll_wait, IO::AIO::poll_cb
224 if IO::AIO::nreqs;
191 225
192 IO::AIO::min_parallel $nthreads 226 IO::AIO::min_parallel $nthreads
193 Set the minimum number of AIO threads to $nthreads. The default is 227 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 228 1, which means a single asynchronous operation can be done at one
195 time (the number of outstanding operations, however, is unlimited). 229 time (the number of outstanding operations, however, is unlimited).

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