… | |
… | |
3 | IO::AIO - Asynchronous Input/Output |
3 | IO::AIO - Asynchronous Input/Output |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use IO::AIO; |
7 | use IO::AIO; |
|
|
8 | |
|
|
9 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
|
|
10 | my ($fh) = @_; |
|
|
11 | ... |
|
|
12 | }; |
|
|
13 | |
|
|
14 | aio_unlink "/tmp/file", sub { }; |
|
|
15 | |
|
|
16 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
|
|
17 | $_[0] > 0 or die "read error: $!"; |
|
|
18 | }; |
|
|
19 | |
|
|
20 | # Event |
|
|
21 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
22 | poll => 'r', |
|
|
23 | cb => \&IO::AIO::poll_cb); |
|
|
24 | |
|
|
25 | # Glib/Gtk2 |
|
|
26 | add_watch Glib::IO IO::AIO::poll_fileno, |
|
|
27 | sub { IO::AIO::poll_cb, 1 }; |
|
|
28 | |
|
|
29 | # Tk |
|
|
30 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
|
|
31 | readable => \&IO::AIO::poll_cb); |
|
|
32 | |
|
|
33 | # Danga::Socket |
|
|
34 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
|
|
35 | \&IO::AIO::poll_cb); |
|
|
36 | |
8 | |
37 | |
9 | =head1 DESCRIPTION |
38 | =head1 DESCRIPTION |
10 | |
39 | |
11 | This module implements asynchronous I/O using whatever means your |
40 | This module implements asynchronous I/O using whatever means your |
12 | operating system supports. |
41 | operating system supports. |
… | |
… | |
21 | remaining functionality would have to be implemented using threads anyway. |
50 | remaining functionality would have to be implemented using threads anyway. |
22 | |
51 | |
23 | Although the module will work with in the presence of other threads, it is |
52 | Although the module will work with in the presence of other threads, it is |
24 | currently not reentrant, so use appropriate locking yourself. |
53 | currently not reentrant, so use appropriate locking yourself. |
25 | |
54 | |
26 | =head2 API NOTES |
55 | =cut |
|
|
56 | |
|
|
57 | package IO::AIO; |
|
|
58 | |
|
|
59 | use base 'Exporter'; |
|
|
60 | |
|
|
61 | use Fcntl (); |
|
|
62 | |
|
|
63 | BEGIN { |
|
|
64 | $VERSION = 0.3; |
|
|
65 | |
|
|
66 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
|
|
67 | aio_fsync aio_fdatasync aio_readahead); |
|
|
68 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
|
|
69 | |
|
|
70 | require XSLoader; |
|
|
71 | XSLoader::load IO::AIO, $VERSION; |
|
|
72 | } |
|
|
73 | |
|
|
74 | =head1 FUNCTIONS |
|
|
75 | |
|
|
76 | =head2 AIO FUNCTIONS |
27 | |
77 | |
28 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
78 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
29 | with the same name (sans C<aio_>). The arguments are similar or identical, |
79 | with the same name (sans C<aio_>). The arguments are similar or identical, |
30 | and they all accept an additional C<$callback> argument which must be |
80 | and they all accept an additional (and optional) C<$callback> argument |
31 | a code reference. This code reference will get called with the syscall |
81 | which must be a code reference. This code reference will get called with |
32 | return code (e.g. most syscalls return C<-1> on error, unlike perl, which |
82 | the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
33 | usually delivers "false") as it's sole argument when the given syscall has |
83 | perl, which usually delivers "false") as it's sole argument when the given |
34 | been executed asynchronously. |
84 | syscall has been executed asynchronously. |
35 | |
85 | |
36 | All functions that expect a filehandle will also accept a file descriptor. |
86 | All functions that expect a filehandle will also accept a file descriptor. |
37 | |
87 | |
38 | The filenames you pass to these routines I<must> be absolute. The reason |
88 | The filenames you pass to these routines I<must> be absolute. The reason |
39 | is that at the time the request is being executed, the current working |
89 | is that at the time the request is being executed, the current working |
40 | directory could have changed. Alternatively, you can make sure that you |
90 | directory could have changed. Alternatively, you can make sure that you |
41 | never change the current working directory. |
91 | never change the current working directory. |
42 | |
92 | |
43 | =over 4 |
93 | =over 4 |
44 | |
|
|
45 | =cut |
|
|
46 | |
|
|
47 | package IO::AIO; |
|
|
48 | |
|
|
49 | use base 'Exporter'; |
|
|
50 | |
|
|
51 | use Fcntl (); |
|
|
52 | |
|
|
53 | BEGIN { |
|
|
54 | $VERSION = 0.1; |
|
|
55 | |
|
|
56 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
|
|
57 | aio_fsync aio_fdatasync aio_readahead); |
|
|
58 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs); |
|
|
59 | |
|
|
60 | require XSLoader; |
|
|
61 | XSLoader::load IO::AIO, $VERSION; |
|
|
62 | } |
|
|
63 | |
|
|
64 | =item IO::AIO::min_parallel $nthreads |
|
|
65 | |
|
|
66 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
|
|
67 | C<1>, which means a single asynchronous operation can be done at one time |
|
|
68 | (the number of outstanding operations, however, is unlimited). |
|
|
69 | |
|
|
70 | It is recommended to keep the number of threads low, as some linux |
|
|
71 | kernel versions will scale negatively with the number of threads (higher |
|
|
72 | parallelity => MUCH higher latency). |
|
|
73 | |
|
|
74 | Under normal circumstances you don't need to call this function, as this |
|
|
75 | module automatically starts a single async thread. |
|
|
76 | |
|
|
77 | =item IO::AIO::max_parallel $nthreads |
|
|
78 | |
|
|
79 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
|
|
80 | the specified number of threads are currently running, kill them. This |
|
|
81 | function blocks until the limit is reached. |
|
|
82 | |
|
|
83 | This module automatically runs C<max_parallel 0> at program end, to ensure |
|
|
84 | that all threads are killed and that there are no outstanding requests. |
|
|
85 | |
|
|
86 | Under normal circumstances you don't need to call this function. |
|
|
87 | |
|
|
88 | =item $fileno = IO::AIO::poll_fileno |
|
|
89 | |
|
|
90 | Return the I<request result pipe filehandle>. This filehandle must be |
|
|
91 | polled for reading by some mechanism outside this module (e.g. Event |
|
|
92 | or select, see below). If the pipe becomes readable you have to call |
|
|
93 | C<poll_cb> to check the results. |
|
|
94 | |
|
|
95 | See C<poll_cb> for an example. |
|
|
96 | |
|
|
97 | =item IO::AIO::poll_cb |
|
|
98 | |
|
|
99 | Process all outstanding events on the result pipe. You have to call this |
|
|
100 | regularly. Returns the number of events processed. Returns immediately |
|
|
101 | when no events are outstanding. |
|
|
102 | |
|
|
103 | You can use Event to multiplex, e.g.: |
|
|
104 | |
|
|
105 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
106 | poll => 'r', async => 1, |
|
|
107 | cb => \&IO::AIO::poll_cb); |
|
|
108 | |
|
|
109 | =item IO::AIO::poll_wait |
|
|
110 | |
|
|
111 | Wait till the result filehandle becomes ready for reading (simply does a |
|
|
112 | select on the filehandle. This is useful if you want to synchronously wait |
|
|
113 | for some requests to finish). |
|
|
114 | |
|
|
115 | See C<nreqs> for an example. |
|
|
116 | |
|
|
117 | =item IO::AIO::nreqs |
|
|
118 | |
|
|
119 | Returns the number of requests currently outstanding. |
|
|
120 | |
|
|
121 | Example: wait till there are no outstanding requests anymore: |
|
|
122 | |
|
|
123 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
124 | while IO::AIO::nreqs; |
|
|
125 | |
94 | |
126 | =item aio_open $pathname, $flags, $mode, $callback |
95 | =item aio_open $pathname, $flags, $mode, $callback |
127 | |
96 | |
128 | Asynchronously open or create a file and call the callback with a newly |
97 | Asynchronously open or create a file and call the callback with a newly |
129 | created filehandle for the file. |
98 | created filehandle for the file. |
… | |
… | |
164 | |
133 | |
165 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
134 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
166 | offset C<0> within the scalar: |
135 | offset C<0> within the scalar: |
167 | |
136 | |
168 | aio_read $fh, 7, 15, $buffer, 0, sub { |
137 | aio_read $fh, 7, 15, $buffer, 0, sub { |
169 | $_[0] >= 0 or die "read error: $!"; |
138 | $_[0] > 0 or die "read error: $!"; |
170 | print "read <$buffer>\n"; |
139 | print "read $_[0] bytes: <$buffer>\n"; |
171 | }; |
140 | }; |
172 | |
141 | |
173 | =item aio_readahead $fh,$offset,$length, $callback |
142 | =item aio_readahead $fh,$offset,$length, $callback |
174 | |
143 | |
175 | Asynchronously reads the specified byte range into the page cache, using |
144 | Asynchronously reads the specified byte range into the page cache, using |
… | |
… | |
220 | =item aio_fdatasync $fh, $callback |
189 | =item aio_fdatasync $fh, $callback |
221 | |
190 | |
222 | Asynchronously call fdatasync on the given filehandle and call the |
191 | Asynchronously call fdatasync on the given filehandle and call the |
223 | callback with the fdatasync result code. |
192 | callback with the fdatasync result code. |
224 | |
193 | |
|
|
194 | =back |
|
|
195 | |
|
|
196 | =head2 SUPPORT FUNCTIONS |
|
|
197 | |
|
|
198 | =over 4 |
|
|
199 | |
|
|
200 | =item $fileno = IO::AIO::poll_fileno |
|
|
201 | |
|
|
202 | Return the I<request result pipe filehandle>. This filehandle must be |
|
|
203 | polled for reading by some mechanism outside this module (e.g. Event |
|
|
204 | or select, see below). If the pipe becomes readable you have to call |
|
|
205 | C<poll_cb> to check the results. |
|
|
206 | |
|
|
207 | See C<poll_cb> for an example. |
|
|
208 | |
|
|
209 | =item IO::AIO::poll_cb |
|
|
210 | |
|
|
211 | Process all outstanding events on the result pipe. You have to call this |
|
|
212 | regularly. Returns the number of events processed. Returns immediately |
|
|
213 | when no events are outstanding. |
|
|
214 | |
|
|
215 | You can use Event to multiplex, e.g.: |
|
|
216 | |
|
|
217 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
218 | poll => 'r', async => 1, |
|
|
219 | cb => \&IO::AIO::poll_cb); |
|
|
220 | |
|
|
221 | =item IO::AIO::poll_wait |
|
|
222 | |
|
|
223 | Wait till the result filehandle becomes ready for reading (simply does a |
|
|
224 | select on the filehandle. This is useful if you want to synchronously wait |
|
|
225 | for some requests to finish). |
|
|
226 | |
|
|
227 | See C<nreqs> for an example. |
|
|
228 | |
|
|
229 | =item IO::AIO::nreqs |
|
|
230 | |
|
|
231 | Returns the number of requests currently outstanding. |
|
|
232 | |
|
|
233 | Example: wait till there are no outstanding requests anymore: |
|
|
234 | |
|
|
235 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
236 | while IO::AIO::nreqs; |
|
|
237 | |
|
|
238 | =item IO::AIO::flush |
|
|
239 | |
|
|
240 | Wait till all outstanding AIO requests have been handled. |
|
|
241 | |
|
|
242 | Strictly equivalent to: |
|
|
243 | |
|
|
244 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
245 | while IO::AIO::nreqs; |
|
|
246 | |
|
|
247 | =item IO::AIO::poll |
|
|
248 | |
|
|
249 | Waits until some requests have been handled. |
|
|
250 | |
|
|
251 | Strictly equivalent to: |
|
|
252 | |
|
|
253 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
254 | if IO::AIO::nreqs; |
|
|
255 | |
|
|
256 | =item IO::AIO::min_parallel $nthreads |
|
|
257 | |
|
|
258 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
|
|
259 | C<1>, which means a single asynchronous operation can be done at one time |
|
|
260 | (the number of outstanding operations, however, is unlimited). |
|
|
261 | |
|
|
262 | It is recommended to keep the number of threads low, as some Linux |
|
|
263 | kernel versions will scale negatively with the number of threads (higher |
|
|
264 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
|
|
265 | threads should be fine. |
|
|
266 | |
|
|
267 | Under normal circumstances you don't need to call this function, as this |
|
|
268 | module automatically starts some threads (the exact number might change, |
|
|
269 | and is currently 4). |
|
|
270 | |
|
|
271 | =item IO::AIO::max_parallel $nthreads |
|
|
272 | |
|
|
273 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
|
|
274 | the specified number of threads are currently running, kill them. This |
|
|
275 | function blocks until the limit is reached. |
|
|
276 | |
|
|
277 | This module automatically runs C<max_parallel 0> at program end, to ensure |
|
|
278 | that all threads are killed and that there are no outstanding requests. |
|
|
279 | |
|
|
280 | Under normal circumstances you don't need to call this function. |
|
|
281 | |
|
|
282 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
|
|
283 | |
|
|
284 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
|
|
285 | try to queue up more than this number of requests, the caller will block until |
|
|
286 | some requests have been handled. |
|
|
287 | |
|
|
288 | The default is very large, so normally there is no practical limit. If you |
|
|
289 | queue up many requests in a loop it it often improves speed if you set |
|
|
290 | this to a relatively low number, such as C<100>. |
|
|
291 | |
|
|
292 | Under normal circumstances you don't need to call this function. |
|
|
293 | |
|
|
294 | =back |
|
|
295 | |
225 | =cut |
296 | =cut |
226 | |
297 | |
227 | # support function to convert a fd into a perl filehandle |
298 | # support function to convert a fd into a perl filehandle |
228 | sub _fd2fh { |
299 | sub _fd2fh { |
229 | return undef if $_[0] < 0; |
300 | return undef if $_[0] < 0; |
… | |
… | |
242 | max_parallel 0; |
313 | max_parallel 0; |
243 | } |
314 | } |
244 | |
315 | |
245 | 1; |
316 | 1; |
246 | |
317 | |
247 | =back |
|
|
248 | |
|
|
249 | =head1 BUGS |
|
|
250 | |
|
|
251 | - could be optimized to use more semaphores instead of filehandles. |
|
|
252 | |
|
|
253 | =head1 SEE ALSO |
318 | =head1 SEE ALSO |
254 | |
319 | |
255 | L<Coro>, L<Linux::AIO>. |
320 | L<Coro>, L<Linux::AIO>. |
256 | |
321 | |
257 | =head1 AUTHOR |
322 | =head1 AUTHOR |