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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC vs.
Revision 1.38 by root, Sun Aug 28 10:51:33 2005 UTC

… …
63use base 'Exporter'; 63use base 'Exporter';
64 64
65use Fcntl (); 65use Fcntl ();
66 66
67BEGIN { 67BEGIN {
68 $VERSION = 1.3; 68 $VERSION = 1.6;
69 69
70
71 @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 stat
71 aio_aio_lstat aio_unlink aio_rmdir aio_readdir aio_symlink
72 aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead); 72 aio_fsync aio_fdatasync aio_readahead);
73 @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);
74 75
75 require XSLoader; 76 require XSLoader;
76 XSLoader::load IO::AIO, $VERSION; 77 XSLoader::load IO::AIO, $VERSION;
77} 78}
78 79
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163 aio_read $fh, 7, 15, $buffer, 0, sub { 164 aio_read $fh, 7, 15, $buffer, 0, sub {
164 $_[0] > 0 or die "read error: $!"; 165 $_[0] > 0 or die "read error: $!";
165 print "read $_[0] bytes: <$buffer>\n"; 166 print "read $_[0] bytes: <$buffer>\n";
166 }; 167 };
167 168
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
168=item aio_readahead $fh,$offset,$length, $callback 192=item aio_readahead $fh,$offset,$length, $callback
169 193
170C<aio_readahead> populates the page cache with data from a file so that 194C<aio_readahead> populates the page cache with data from a file so that
171subsequent reads from that file will not block on disk I/O. The C<$offset> 195subsequent reads from that file will not block on disk I/O. The C<$offset>
172argument 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
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209=item aio_rmdir $pathname, $callback 233=item aio_rmdir $pathname, $callback
210 234
211Asynchronously rmdir (delete) a directory and call the callback with the 235Asynchronously rmdir (delete) a directory and call the callback with the
212result code. 236result code.
213 237
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
214=item aio_fsync $fh, $callback 247=item aio_fsync $fh, $callback
215 248
216Asynchronously call fsync on the given filehandle and call the callback 249Asynchronously call fsync on the given filehandle and call the callback
217with the fsync result code. 250with the fsync result code.
218 251
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288 IO::AIO::poll_wait, IO::AIO::poll_cb 321 IO::AIO::poll_wait, IO::AIO::poll_cb
289 if IO::AIO::nreqs; 322 if IO::AIO::nreqs;
290 323
291=item IO::AIO::min_parallel $nthreads 324=item IO::AIO::min_parallel $nthreads
292 325
293Set the minimum number of AIO threads to C<$nthreads>. The default is 326Set the minimum number of AIO threads to C<$nthreads>. The current default
294C<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
295(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.
296 332
297It 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
298kernel versions will scale negatively with the number of threads (higher 334kernel versions will scale negatively with the number of threads (higher
299parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 335parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
300threads should be fine. 336threads should be fine.
301 337
302Under 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
303module automatically starts some threads (the exact number might change, 339module selects a default that is suitable for low to moderate load.
304and is currently 4).
305 340
306=item IO::AIO::max_parallel $nthreads 341=item IO::AIO::max_parallel $nthreads
307 342
308Sets the maximum number of AIO threads to C<$nthreads>. If more than 343Sets the maximum number of AIO threads to C<$nthreads>. If more than the
309the specified number of threads are currently running, kill them. This 344specified number of threads are currently running, this function kills
310function blocks until the limit is reached. 345them. This function blocks until the limit is reached.
346
347While C<$nthreads> are zero, aio requests get queued but not executed
348until the number of threads has been increased again.
311 349
312This 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
313that all threads are killed and that there are no outstanding requests. 351that all threads are killed and that there are no outstanding requests.
314 352
315Under normal circumstances you don't need to call this function. 353Under normal circumstances you don't need to call this function.
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319Sets the maximum number of outstanding requests to C<$nreqs>. If you 357Sets the maximum number of outstanding requests to C<$nreqs>. If you
320try 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
321some requests have been handled. 359some requests have been handled.
322 360
323The 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
324queue 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
325this to a relatively low number, such as C<100>. 363this to a relatively low number, such as C<100>.
326 364
327Under normal circumstances you don't need to call this function. 365Under normal circumstances you don't need to call this function.
328 366
329=back 367=back
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354 392
3551; 3931;
356 394
357=head2 FORK BEHAVIOUR 395=head2 FORK BEHAVIOUR
358 396
359Before 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
360added 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
361the parent simply leaves the quiescent state and continues request/result 399the fork the parent simply leaves the quiescent state and continues
362processing, while the child clears the request/result queue and starts the 400request/result processing, while the child clears the request/result
363same 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.
364 404
365=head1 SEE ALSO 405=head1 SEE ALSO
366 406
367L<Coro>, L<Linux::AIO>. 407L<Coro>, L<Linux::AIO>.
368 408

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