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Revision 1.12 by root, Mon Jul 11 01:03:17 2005 UTC vs.
Revision 1.34 by root, Thu Aug 18 16:32:10 2005 UTC

… …
22 poll => 'r', 22 poll => 'r',
23 cb => \&IO::AIO::poll_cb); 23 cb => \&IO::AIO::poll_cb);
24 24
25 # Glib/Gtk2 25 # Glib/Gtk2
26 add_watch Glib::IO IO::AIO::poll_fileno, 26 add_watch Glib::IO IO::AIO::poll_fileno,
27 \&IO::AIO::poll_cb; 27 in => sub { IO::AIO::poll_cb; 1 };
28 28
29 # Tk 29 # Tk
30 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", 30 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31 readable => \&IO::AIO::poll_cb); 31 readable => \&IO::AIO::poll_cb);
32 32
… …
48not well-supported (Linux doesn't allow them on normal files currently, 48not well-supported (Linux doesn't allow them on normal files currently,
49for example), and they would only support aio_read and aio_write, so the 49for example), and they would only support aio_read and aio_write, so the
50remaining functionality would have to be implemented using threads anyway. 50remaining functionality would have to be implemented using threads anyway.
51 51
52Although the module will work with in the presence of other threads, it is 52Although the module will work with in the presence of other threads, it is
53currently not reentrant, so use appropriate locking yourself. 53currently not reentrant, so use appropriate locking yourself, always call
54C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
55C<aio_> functions) recursively.
54 56
55=cut 57=cut
56 58
57package IO::AIO; 59package IO::AIO;
58 60
61no warnings;
62
59use base 'Exporter'; 63use base 'Exporter';
60 64
61use Fcntl (); 65use Fcntl ();
62 66
63BEGIN { 67BEGIN {
64 $VERSION = 0.3; 68 $VERSION = 1.5;
65 69
66 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink 70 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
67 aio_fsync aio_fdatasync aio_readahead); 71 aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
68 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); 72 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
69 73
70 require XSLoader; 74 require XSLoader;
71 XSLoader::load IO::AIO, $VERSION; 75 XSLoader::load IO::AIO, $VERSION;
72} 76}
… …
75 79
76=head2 AIO FUNCTIONS 80=head2 AIO FUNCTIONS
77 81
78All the C<aio_*> calls are more or less thin wrappers around the syscall 82All the C<aio_*> calls are more or less thin wrappers around the syscall
79with the same name (sans C<aio_>). The arguments are similar or identical, 83with the same name (sans C<aio_>). The arguments are similar or identical,
80and they all accept an additional C<$callback> argument which must be 84and they all accept an additional (and optional) C<$callback> argument
81a code reference. This code reference will get called with the syscall 85which must be a code reference. This code reference will get called with
82return code (e.g. most syscalls return C<-1> on error, unlike perl, which 86the syscall return code (e.g. most syscalls return C<-1> on error, unlike
83usually delivers "false") as it's sole argument when the given syscall has 87perl, which usually delivers "false") as it's sole argument when the given
84been executed asynchronously. 88syscall has been executed asynchronously.
85 89
86All functions that expect a filehandle will also accept a file descriptor. 90All functions expecting a filehandle keep a copy of the filehandle
91internally until the request has finished.
87 92
88The filenames you pass to these routines I<must> be absolute. The reason 93The pathnames you pass to these routines I<must> be absolute and
89is that at the time the request is being executed, the current working 94encoded in byte form. The reason for the former is that at the time the
90directory could have changed. Alternatively, you can make sure that you 95request is being executed, the current working directory could have
96changed. Alternatively, you can make sure that you never change the
91never change the current working directory. 97current working directory.
98
99To encode pathnames to byte form, either make sure you either: a)
100always pass in filenames you got from outside (command line, readdir
101etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
102your pathnames to the locale (or other) encoding in effect in the user
103environment, d) use Glib::filename_from_unicode on unicode filenames or e)
104use something else.
92 105
93=over 4 106=over 4
94 107
95=item aio_open $pathname, $flags, $mode, $callback 108=item aio_open $pathname, $flags, $mode, $callback
96 109
… …
98created filehandle for the file. 111created filehandle for the file.
99 112
100The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 113The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
101for an explanation. 114for an explanation.
102 115
103The C<$mode> argument is a bitmask. See the C<Fcntl> module for a 116The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
104list. They are the same as used in C<sysopen>. 117list. They are the same as used by C<sysopen>.
118
119Likewise, C<$mode> specifies the mode of the newly created file, if it
120didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
121except that it is mandatory (i.e. use C<0> if you don't create new files,
122and C<0666> or C<0777> if you do).
105 123
106Example: 124Example:
107 125
108 aio_open "/etc/passwd", O_RDONLY, 0, sub { 126 aio_open "/etc/passwd", O_RDONLY, 0, sub {
109 if ($_[0]) { 127 if ($_[0]) {
… …
116 134
117=item aio_close $fh, $callback 135=item aio_close $fh, $callback
118 136
119Asynchronously close a file and call the callback with the result 137Asynchronously close a file and call the callback with the result
120code. I<WARNING:> although accepted, you should not pass in a perl 138code. I<WARNING:> although accepted, you should not pass in a perl
121filehandle here, as perl will likely close the file descriptor itself when 139filehandle here, as perl will likely close the file descriptor another
122the filehandle is destroyed. Normally, you can safely call perls C<close> 140time when the filehandle is destroyed. Normally, you can safely call perls
123or just let filehandles go out of scope. 141C<close> or just let filehandles go out of scope.
142
143This is supposed to be a bug in the API, so that might change. It's
144therefore best to avoid this function.
124 145
125=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback 146=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
126 147
127=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback 148=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
128 149
129Reads or writes C<length> bytes from the specified C<fh> and C<offset> 150Reads or writes C<length> bytes from the specified C<fh> and C<offset>
130into the scalar given by C<data> and offset C<dataoffset> and calls the 151into the scalar given by C<data> and offset C<dataoffset> and calls the
131callback without the actual number of bytes read (or -1 on error, just 152callback without the actual number of bytes read (or -1 on error, just
132like the syscall). 153like the syscall).
133 154
155The C<$data> scalar I<MUST NOT> be modified in any way while the request
156is outstanding. Modifying it can result in segfaults or WW3 (if the
157necessary/optional hardware is installed).
158
134Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at 159Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
135offset C<0> within the scalar: 160offset C<0> within the scalar:
136 161
137 aio_read $fh, 7, 15, $buffer, 0, sub { 162 aio_read $fh, 7, 15, $buffer, 0, sub {
138 $_[0] > 0 or die "read error: $!"; 163 $_[0] > 0 or die "read error: $!";
139 print "read $_[0] bytes: <$buffer>\n"; 164 print "read $_[0] bytes: <$buffer>\n";
140 }; 165 };
141 166
142=item aio_readahead $fh,$offset,$length, $callback 167=item aio_readahead $fh,$offset,$length, $callback
143 168
144Asynchronously reads the specified byte range into the page cache, using
145the C<readahead> syscall. If that syscall doesn't exist the status will be
146C<-1> and C<$!> is set to ENOSYS.
147
148readahead() populates the page cache with data from a file so that 169C<aio_readahead> populates the page cache with data from a file so that
149subsequent reads from that file will not block on disk I/O. The C<$offset> 170subsequent reads from that file will not block on disk I/O. The C<$offset>
150argument specifies the starting point from which data is to be read and 171argument specifies the starting point from which data is to be read and
151C<$length> specifies the number of bytes to be read. I/O is performed in 172C<$length> specifies the number of bytes to be read. I/O is performed in
152whole pages, so that offset is effectively rounded down to a page boundary 173whole pages, so that offset is effectively rounded down to a page boundary
153and bytes are read up to the next page boundary greater than or equal to 174and bytes are read up to the next page boundary greater than or equal to
154(off-set+length). aio_readahead() does not read beyond the end of the 175(off-set+length). C<aio_readahead> does not read beyond the end of the
155file. The current file offset of the file is left unchanged. 176file. The current file offset of the file is left unchanged.
177
178If that syscall doesn't exist (likely if your OS isn't Linux) it will be
179emulated by simply reading the data, which would have a similar effect.
156 180
157=item aio_stat $fh_or_path, $callback 181=item aio_stat $fh_or_path, $callback
158 182
159=item aio_lstat $fh, $callback 183=item aio_lstat $fh, $callback
160 184
… …
179=item aio_unlink $pathname, $callback 203=item aio_unlink $pathname, $callback
180 204
181Asynchronously unlink (delete) a file and call the callback with the 205Asynchronously unlink (delete) a file and call the callback with the
182result code. 206result code.
183 207
208=item aio_rmdir $pathname, $callback
209
210Asynchronously rmdir (delete) a directory and call the callback with the
211result code.
212
184=item aio_fsync $fh, $callback 213=item aio_fsync $fh, $callback
185 214
186Asynchronously call fsync on the given filehandle and call the callback 215Asynchronously call fsync on the given filehandle and call the callback
187with the fsync result code. 216with the fsync result code.
188 217
189=item aio_fdatasync $fh, $callback 218=item aio_fdatasync $fh, $callback
190 219
191Asynchronously call fdatasync on the given filehandle and call the 220Asynchronously call fdatasync on the given filehandle and call the
192callback with the fdatasync result code. 221callback with the fdatasync result code.
193 222
223If this call isn't available because your OS lacks it or it couldn't be
224detected, it will be emulated by calling C<fsync> instead.
225
194=back 226=back
195 227
196=head2 SUPPORT FUNCTIONS 228=head2 SUPPORT FUNCTIONS
197 229
198=over 4 230=over 4
199 231
200=item $fileno = IO::AIO::poll_fileno 232=item $fileno = IO::AIO::poll_fileno
201 233
202Return the I<request result pipe filehandle>. This filehandle must be 234Return the I<request result pipe file descriptor>. This filehandle must be
203polled for reading by some mechanism outside this module (e.g. Event 235polled for reading by some mechanism outside this module (e.g. Event or
204or select, see below). If the pipe becomes readable you have to call 236select, see below or the SYNOPSIS). If the pipe becomes readable you have
205C<poll_cb> to check the results. 237to call C<poll_cb> to check the results.
206 238
207See C<poll_cb> for an example. 239See C<poll_cb> for an example.
208 240
209=item IO::AIO::poll_cb 241=item IO::AIO::poll_cb
210 242
211Process all outstanding events on the result pipe. You have to call this 243Process all outstanding events on the result pipe. You have to call this
212regularly. Returns the number of events processed. Returns immediately 244regularly. Returns the number of events processed. Returns immediately
213when no events are outstanding. 245when no events are outstanding.
214 246
215You can use Event to multiplex, e.g.: 247Example: Install an Event watcher that automatically calls
248IO::AIO::poll_cb with high priority:
216 249
217 Event->io (fd => IO::AIO::poll_fileno, 250 Event->io (fd => IO::AIO::poll_fileno,
218 poll => 'r', async => 1, 251 poll => 'r', async => 1,
219 cb => \&IO::AIO::poll_cb); 252 cb => \&IO::AIO::poll_cb);
220 253
221=item IO::AIO::poll_wait 254=item IO::AIO::poll_wait
222 255
223Wait till the result filehandle becomes ready for reading (simply does a 256Wait till the result filehandle becomes ready for reading (simply does a
224select on the filehandle. This is useful if you want to synchronously wait 257C<select> on the filehandle. This is useful if you want to synchronously wait
225for some requests to finish). 258for some requests to finish).
226 259
227See C<nreqs> for an example. 260See C<nreqs> for an example.
228 261
229=item IO::AIO::nreqs 262=item IO::AIO::nreqs
230 263
231Returns the number of requests currently outstanding. 264Returns the number of requests currently outstanding (i.e. for which their
265callback has not been invoked yet).
232 266
233Example: wait till there are no outstanding requests anymore: 267Example: wait till there are no outstanding requests anymore:
234 268
235 IO::AIO::poll_wait, IO::AIO::poll_cb 269 IO::AIO::poll_wait, IO::AIO::poll_cb
236 while IO::AIO::nreqs; 270 while IO::AIO::nreqs;
237 271
238=item IO::AIO::flush 272=item IO::AIO::flush
239 273
240Wait till all outstanding AIO requests have been handled. 274Wait till all outstanding AIO requests have been handled.
241 275
276Strictly equivalent to:
277
278 IO::AIO::poll_wait, IO::AIO::poll_cb
279 while IO::AIO::nreqs;
280
281=item IO::AIO::poll
282
283Waits until some requests have been handled.
284
285Strictly equivalent to:
286
287 IO::AIO::poll_wait, IO::AIO::poll_cb
288 if IO::AIO::nreqs;
289
242=item IO::AIO::min_parallel $nthreads 290=item IO::AIO::min_parallel $nthreads
243 291
244Set the minimum number of AIO threads to C<$nthreads>. The default is 292Set the minimum number of AIO threads to C<$nthreads>. The current default
245C<1>, which means a single asynchronous operation can be done at one time 293is C<4>, which means four asynchronous operations can be done at one time
246(the number of outstanding operations, however, is unlimited). 294(the number of outstanding operations, however, is unlimited).
295
296IO::AIO starts threads only on demand, when an AIO request is queued and
297no free thread exists.
247 298
248It is recommended to keep the number of threads low, as some Linux 299It is recommended to keep the number of threads low, as some Linux
249kernel versions will scale negatively with the number of threads (higher 300kernel versions will scale negatively with the number of threads (higher
250parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 301parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
251threads should be fine. 302threads should be fine.
252 303
253Under normal circumstances you don't need to call this function, as this 304Under most circumstances you don't need to call this function, as the
254module automatically starts some threads (the exact number might change, 305module selects a default that is suitable for low to moderate load.
255and is currently 4).
256 306
257=item IO::AIO::max_parallel $nthreads 307=item IO::AIO::max_parallel $nthreads
258 308
259Sets the maximum number of AIO threads to C<$nthreads>. If more than 309Sets the maximum number of AIO threads to C<$nthreads>. If more than the
260the specified number of threads are currently running, kill them. This 310specified number of threads are currently running, this function kills
261function blocks until the limit is reached. 311them. This function blocks until the limit is reached.
312
313While C<$nthreads> are zero, aio requests get queued but not executed
314until the number of threads has been increased again.
262 315
263This module automatically runs C<max_parallel 0> at program end, to ensure 316This module automatically runs C<max_parallel 0> at program end, to ensure
264that all threads are killed and that there are no outstanding requests. 317that all threads are killed and that there are no outstanding requests.
265 318
266Under normal circumstances you don't need to call this function. 319Under normal circumstances you don't need to call this function.
… …
270Sets the maximum number of outstanding requests to C<$nreqs>. If you 323Sets the maximum number of outstanding requests to C<$nreqs>. If you
271try to queue up more than this number of requests, the caller will block until 324try to queue up more than this number of requests, the caller will block until
272some requests have been handled. 325some requests have been handled.
273 326
274The default is very large, so normally there is no practical limit. If you 327The default is very large, so normally there is no practical limit. If you
275queue up many requests in a loop it it often improves speed if you set 328queue up many requests in a loop it often improves speed if you set
276this to a relatively low number, such as C<100>. 329this to a relatively low number, such as C<100>.
277 330
278Under normal circumstances you don't need to call this function. 331Under normal circumstances you don't need to call this function.
279 332
280=back 333=back
… …
283 336
284# support function to convert a fd into a perl filehandle 337# support function to convert a fd into a perl filehandle
285sub _fd2fh { 338sub _fd2fh {
286 return undef if $_[0] < 0; 339 return undef if $_[0] < 0;
287 340
288 # try to be perl5.6-compatible 341 # try to generate nice filehandles
289 local *AIO_FH; 342 my $sym = "IO::AIO::fd#$_[0]";
290 open AIO_FH, "+<&=$_[0]" 343 local *$sym;
344
345 open *$sym, "+<&=$_[0]" # usually works under any unix
346 or open *$sym, "<&=$_[0]" # cygwin needs this
347 or open *$sym, ">&=$_[0]" # or this
291 or return undef; 348 or return undef;
292 349
293 *AIO_FH 350 *$sym
294} 351}
295 352
296min_parallel 4; 353min_parallel 4;
297 354
298END { 355END {
299 max_parallel 0; 356 max_parallel 0;
300} 357}
301 358
3021; 3591;
303 360
361=head2 FORK BEHAVIOUR
362
363Before the fork, IO::AIO enters a quiescent state where no requests
364can be added in other threads and no results will be processed. After
365the fork the parent simply leaves the quiescent state and continues
366request/result processing, while the child clears the request/result
367queue (so the requests started before the fork will only be handled in
368the parent). Threats will be started on demand until the limit ste in the
369parent process has been reached again.
370
304=head1 SEE ALSO 371=head1 SEE ALSO
305 372
306L<Coro>, L<Linux::AIO>. 373L<Coro>, L<Linux::AIO>.
307 374
308=head1 AUTHOR 375=head1 AUTHOR

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