ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/AIO.pm
(Generate patch)

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.31 by root, Wed Aug 17 05:06:59 2005 UTC vs.
Revision 1.39 by root, Sun Aug 28 11:05:50 2005 UTC

… …
63use base 'Exporter'; 63use base 'Exporter';
64 64
65use Fcntl (); 65use Fcntl ();
66 66
67BEGIN { 67BEGIN {
68 $VERSION = 1.2; 68 $VERSION = 1.6;
69 69
70 @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink 70 @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
71 aio_lstat aio_unlink aio_rmdir aio_readdir aio_symlink
71 aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead); 72 aio_fsync aio_fdatasync aio_readahead);
72 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); 73 @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel
74 max_outstanding nreqs);
73 75
74 require XSLoader; 76 require XSLoader;
75 XSLoader::load IO::AIO, $VERSION; 77 XSLoader::load IO::AIO, $VERSION;
76} 78}
77 79
… …
162 aio_read $fh, 7, 15, $buffer, 0, sub { 164 aio_read $fh, 7, 15, $buffer, 0, sub {
163 $_[0] > 0 or die "read error: $!"; 165 $_[0] > 0 or die "read error: $!";
164 print "read $_[0] bytes: <$buffer>\n"; 166 print "read $_[0] bytes: <$buffer>\n";
165 }; 167 };
166 168
169=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback
170
171Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
172reading at byte offset C<$in_offset>, and starts writing at the current
173file offset of C<$out_fh>. Because of that, it is not safe to issue more
174than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
175other.
176
177This call tries to make use of a native C<sendfile> syscall to provide
178zero-copy operation. For this to work, C<$out_fh> should refer to a
179socket, and C<$in_fh> should refer to mmap'able file.
180
181If the native sendfile call fails or is not implemented, it will be
182emulated, so you can call C<aio_sendfile> on any type of filehandle
183regardless of the limitations of the operating system.
184
185Please note, however, that C<aio_sendfile> can read more bytes from
186C<$in_fh> than are written, and there is no way to find out how many
187bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
188provides the number of bytes written to C<$out_fh>. Only if the result
189value equals C<$length> one can assume that C<$length> bytes have been
190read.
191
167=item aio_readahead $fh,$offset,$length, $callback 192=item aio_readahead $fh,$offset,$length, $callback
168 193
169C<aio_readahead> populates the page cache with data from a file so that 194C<aio_readahead> populates the page cache with data from a file so that
170subsequent reads from that file will not block on disk I/O. The C<$offset> 195subsequent reads from that file will not block on disk I/O. The C<$offset>
171argument specifies the starting point from which data is to be read and 196argument specifies the starting point from which data is to be read and
… …
208=item aio_rmdir $pathname, $callback 233=item aio_rmdir $pathname, $callback
209 234
210Asynchronously rmdir (delete) a directory and call the callback with the 235Asynchronously rmdir (delete) a directory and call the callback with the
211result code. 236result code.
212 237
238=item aio_readdir $pathname $callback
239
240Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
241directory (i.e. opendir + readdir + closedir). The entries will not be
242sorted, and will B<NOT> include the C<.> and C<..> entries.
243
244The callback a single argument which is either C<undef> or an array-ref
245with the filenames.
246
213=item aio_fsync $fh, $callback 247=item aio_fsync $fh, $callback
214 248
215Asynchronously call fsync on the given filehandle and call the callback 249Asynchronously call fsync on the given filehandle and call the callback
216with the fsync result code. 250with the fsync result code.
217 251
… …
287 IO::AIO::poll_wait, IO::AIO::poll_cb 321 IO::AIO::poll_wait, IO::AIO::poll_cb
288 if IO::AIO::nreqs; 322 if IO::AIO::nreqs;
289 323
290=item IO::AIO::min_parallel $nthreads 324=item IO::AIO::min_parallel $nthreads
291 325
292Set the minimum number of AIO threads to C<$nthreads>. The default is 326Set the minimum number of AIO threads to C<$nthreads>. The current default
293C<1>, which means a single asynchronous operation can be done at one time 327is C<4>, which means four asynchronous operations can be done at one time
294(the number of outstanding operations, however, is unlimited). 328(the number of outstanding operations, however, is unlimited).
329
330IO::AIO starts threads only on demand, when an AIO request is queued and
331no free thread exists.
295 332
296It is recommended to keep the number of threads low, as some Linux 333It is recommended to keep the number of threads low, as some Linux
297kernel versions will scale negatively with the number of threads (higher 334kernel versions will scale negatively with the number of threads (higher
298parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 335parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
299threads should be fine. 336threads should be fine.
300 337
301Under normal circumstances you don't need to call this function, as this 338Under most circumstances you don't need to call this function, as the
302module automatically starts some threads (the exact number might change, 339module selects a default that is suitable for low to moderate load.
303and is currently 4).
304 340
305=item IO::AIO::max_parallel $nthreads 341=item IO::AIO::max_parallel $nthreads
306 342
307Sets the maximum number of AIO threads to C<$nthreads>. If more than 343Sets the maximum number of AIO threads to C<$nthreads>. If more than the
308the specified number of threads are currently running, kill them. This 344specified number of threads are currently running, this function kills
309function blocks until the limit is reached. 345them. This function blocks until the limit is reached.
346
347While C<$nthreads> are zero, aio requests get queued but not executed
348until the number of threads has been increased again.
310 349
311This module automatically runs C<max_parallel 0> at program end, to ensure 350This module automatically runs C<max_parallel 0> at program end, to ensure
312that all threads are killed and that there are no outstanding requests. 351that all threads are killed and that there are no outstanding requests.
313 352
314Under normal circumstances you don't need to call this function. 353Under normal circumstances you don't need to call this function.
… …
318Sets the maximum number of outstanding requests to C<$nreqs>. If you 357Sets the maximum number of outstanding requests to C<$nreqs>. If you
319try to queue up more than this number of requests, the caller will block until 358try to queue up more than this number of requests, the caller will block until
320some requests have been handled. 359some requests have been handled.
321 360
322The default is very large, so normally there is no practical limit. If you 361The default is very large, so normally there is no practical limit. If you
323queue up many requests in a loop it it often improves speed if you set 362queue up many requests in a loop it often improves speed if you set
324this to a relatively low number, such as C<100>. 363this to a relatively low number, such as C<100>.
325 364
326Under normal circumstances you don't need to call this function. 365Under normal circumstances you don't need to call this function.
327 366
328=back 367=back
… …
353 392
3541; 3931;
355 394
356=head2 FORK BEHAVIOUR 395=head2 FORK BEHAVIOUR
357 396
358Before the fork IO::AIO enters a quiescent state where no requests can be 397Before the fork, IO::AIO enters a quiescent state where no requests
359added in other threads and no results will be processed. After the fork 398can be added in other threads and no results will be processed. After
360the parent simply leaves the quiescent state and continues request/result 399the fork the parent simply leaves the quiescent state and continues
361processing, while the child clears the request/result queue and starts the 400request/result processing, while the child clears the request/result
362same number of threads as were in use by the parent. 401queue (so the requests started before the fork will only be handled in
402the parent). Threats will be started on demand until the limit ste in the
403parent process has been reached again.
363 404
364=head1 SEE ALSO 405=head1 SEE ALSO
365 406
366L<Coro>, L<Linux::AIO>. 407L<Coro>, L<Linux::AIO>.
367 408

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines