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Revision 1.2 by root, Sun Jul 10 18:16:49 2005 UTC vs.
Revision 1.4 by root, Sun Jul 10 21:04:46 2005 UTC

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19 using threads anyway. 19 using threads anyway.
20 20
21 Although the module will work with in the presence of other threads, it 21 Although the module will work with in the presence of other threads, it
22 is currently not reentrant, so use appropriate locking yourself. 22 is currently not reentrant, so use appropriate locking yourself.
23 23
24 API NOTES 24FUNCTIONS
25 AIO FUNCTIONS
25 All the "aio_*" calls are more or less thin wrappers around the syscall 26 All the "aio_*" calls are more or less thin wrappers around the syscall
26 with the same name (sans "aio_"). The arguments are similar or 27 with the same name (sans "aio_"). The arguments are similar or
27 identical, and they all accept an additional $callback argument which 28 identical, and they all accept an additional $callback argument which
28 must be a code reference. This code reference will get called with the 29 must be a code reference. This code reference will get called with the
29 syscall return code (e.g. most syscalls return -1 on error, unlike perl, 30 syscall return code (e.g. most syscalls return -1 on error, unlike perl,
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35 36
36 The filenames you pass to these routines *must* be absolute. The reason 37 The filenames you pass to these routines *must* be absolute. The reason
37 is that at the time the request is being executed, the current working 38 is that at the time the request is being executed, the current working
38 directory could have changed. Alternatively, you can make sure that you 39 directory could have changed. Alternatively, you can make sure that you
39 never change the current working directory. 40 never change the current working directory.
40
41 IO::AIO::min_parallel $nthreads
42 Set the minimum number of AIO threads to $nthreads. The default is
43 1, which means a single asynchronous operation can be done at one
44 time (the number of outstanding operations, however, is unlimited).
45
46 It is recommended to keep the number of threads low, as some linux
47 kernel versions will scale negatively with the number of threads
48 (higher parallelity => MUCH higher latency).
49
50 Under normal circumstances you don't need to call this function, as
51 this module automatically starts a single async thread.
52
53 IO::AIO::max_parallel $nthreads
54 Sets the maximum number of AIO threads to $nthreads. If more than
55 the specified number of threads are currently running, kill them.
56 This function blocks until the limit is reached.
57
58 This module automatically runs "max_parallel 0" at program end, to
59 ensure that all threads are killed and that there are no outstanding
60 requests.
61
62 Under normal circumstances you don't need to call this function.
63
64 $fileno = IO::AIO::poll_fileno
65 Return the *request result pipe filehandle*. This filehandle must be
66 polled for reading by some mechanism outside this module (e.g. Event
67 or select, see below). If the pipe becomes readable you have to call
68 "poll_cb" to check the results.
69
70 See "poll_cb" for an example.
71
72 IO::AIO::poll_cb
73 Process all outstanding events on the result pipe. You have to call
74 this regularly. Returns the number of events processed. Returns
75 immediately when no events are outstanding.
76
77 You can use Event to multiplex, e.g.:
78
79 Event->io (fd => IO::AIO::poll_fileno,
80 poll => 'r', async => 1,
81 cb => \&IO::AIO::poll_cb);
82
83 IO::AIO::poll_wait
84 Wait till the result filehandle becomes ready for reading (simply
85 does a select on the filehandle. This is useful if you want to
86 synchronously wait for some requests to finish).
87
88 See "nreqs" for an example.
89
90 IO::AIO::nreqs
91 Returns the number of requests currently outstanding.
92
93 Example: wait till there are no outstanding requests anymore:
94
95 IO::AIO::poll_wait, IO::AIO::poll_cb
96 while IO::AIO::nreqs;
97 41
98 aio_open $pathname, $flags, $mode, $callback 42 aio_open $pathname, $flags, $mode, $callback
99 Asynchronously open or create a file and call the callback with a 43 Asynchronously open or create a file and call the callback with a
100 newly created filehandle for the file. 44 newly created filehandle for the file.
101 45
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184 128
185 aio_fdatasync $fh, $callback 129 aio_fdatasync $fh, $callback
186 Asynchronously call fdatasync on the given filehandle and call the 130 Asynchronously call fdatasync on the given filehandle and call the
187 callback with the fdatasync result code. 131 callback with the fdatasync result code.
188 132
189BUGS 133 SUPPORT FUNCTIONS
190 - could be optimized to use more semaphores instead of filehandles. 134 $fileno = IO::AIO::poll_fileno
135 Return the *request result pipe filehandle*. This filehandle must be
136 polled for reading by some mechanism outside this module (e.g. Event
137 or select, see below). If the pipe becomes readable you have to call
138 "poll_cb" to check the results.
139
140 See "poll_cb" for an example.
141
142 IO::AIO::poll_cb
143 Process all outstanding events on the result pipe. You have to call
144 this regularly. Returns the number of events processed. Returns
145 immediately when no events are outstanding.
146
147 You can use Event to multiplex, e.g.:
148
149 Event->io (fd => IO::AIO::poll_fileno,
150 poll => 'r', async => 1,
151 cb => \&IO::AIO::poll_cb);
152
153 IO::AIO::poll_wait
154 Wait till the result filehandle becomes ready for reading (simply
155 does a select on the filehandle. This is useful if you want to
156 synchronously wait for some requests to finish).
157
158 See "nreqs" for an example.
159
160 IO::AIO::nreqs
161 Returns the number of requests currently outstanding.
162
163 Example: wait till there are no outstanding requests anymore:
164
165 IO::AIO::poll_wait, IO::AIO::poll_cb
166 while IO::AIO::nreqs;
167
168 IO::AIO::min_parallel $nthreads
169 Set the minimum number of AIO threads to $nthreads. The default is
170 1, which means a single asynchronous operation can be done at one
171 time (the number of outstanding operations, however, is unlimited).
172
173 It is recommended to keep the number of threads low, as some Linux
174 kernel versions will scale negatively with the number of threads
175 (higher parallelity => MUCH higher latency). With current Linux 2.6
176 versions, 4-32 threads should be fine.
177
178 Under normal circumstances you don't need to call this function, as
179 this module automatically starts some threads (the exact number
180 might change, and is currently 4).
181
182 IO::AIO::max_parallel $nthreads
183 Sets the maximum number of AIO threads to $nthreads. If more than
184 the specified number of threads are currently running, kill them.
185 This function blocks until the limit is reached.
186
187 This module automatically runs "max_parallel 0" at program end, to
188 ensure that all threads are killed and that there are no outstanding
189 requests.
190
191 Under normal circumstances you don't need to call this function.
192
193 $oldnreqs = IO::AIO::max_outstanding $nreqs
194 Sets the maximum number of outstanding requests to $nreqs. If you
195 try to queue up more than this number of requests, the caller will
196 block until some requests have been handled.
197
198 The default is very large, so normally there is no practical limit.
199 If you queue up many requests in a loop it it often improves speed
200 if you set this to a relatively low number, such as 100.
201
202 Under normal circumstances you don't need to call this function.
191 203
192SEE ALSO 204SEE ALSO
193 Coro, Linux::AIO. 205 Coro, Linux::AIO.
194 206
195AUTHOR 207AUTHOR

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