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Revision 1.194 by root, Fri May 27 00:44:49 2011 UTC vs.
Revision 1.233 by root, Mon Aug 13 01:01:04 2012 UTC

… …
168use common::sense; 168use common::sense;
169 169
170use base 'Exporter'; 170use base 'Exporter';
171 171
172BEGIN { 172BEGIN {
173 our $VERSION = '3.9'; 173 our $VERSION = '4.15';
174 174
175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
178 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead aio_fiemap
179 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
180 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
181 aio_chmod aio_utime aio_truncate 182 aio_chmod aio_utime aio_truncate
182 aio_msync aio_mtouch aio_mlock aio_mlockall 183 aio_msync aio_mtouch aio_mlock aio_mlockall
183 aio_statvfs); 184 aio_statvfs
185 aio_wd);
184 186
185 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187 min_parallel max_parallel max_idle idle_timeout 189 min_parallel max_parallel max_idle idle_timeout
188 nreqs nready npending nthreads 190 nreqs nready npending nthreads
… …
200 202
201=head1 FUNCTIONS 203=head1 FUNCTIONS
202 204
203=head2 QUICK OVERVIEW 205=head2 QUICK OVERVIEW
204 206
205This section simply lists the prototypes of the most important functions 207This section simply lists the prototypes most of the functions for
206for quick reference. See the following sections for function-by-function 208quick reference. See the following sections for function-by-function
207documentation. 209documentation.
208 210
211 aio_wd $pathname, $callback->($wd)
209 aio_open $pathname, $flags, $mode, $callback->($fh) 212 aio_open $pathname, $flags, $mode, $callback->($fh)
210 aio_close $fh, $callback->($status) 213 aio_close $fh, $callback->($status)
214 aio_seek $fh,$offset,$whence, $callback->($offs)
211 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 215 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 216 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 217 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214 aio_readahead $fh,$offset,$length, $callback->($retval) 218 aio_readahead $fh,$offset,$length, $callback->($retval)
215 aio_stat $fh_or_path, $callback->($status) 219 aio_stat $fh_or_path, $callback->($status)
216 aio_lstat $fh, $callback->($status) 220 aio_lstat $fh, $callback->($status)
217 aio_statvfs $fh_or_path, $callback->($statvfs) 221 aio_statvfs $fh_or_path, $callback->($statvfs)
218 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 223 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
220 aio_truncate $fh_or_path, $offset, $callback->($status) 225 aio_truncate $fh_or_path, $offset, $callback->($status)
221 aio_chmod $fh_or_path, $mode, $callback->($status) 226 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
227 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222 aio_unlink $pathname, $callback->($status) 228 aio_unlink $pathname, $callback->($status)
223 aio_mknod $path, $mode, $dev, $callback->($status) 229 aio_mknod $pathname, $mode, $dev, $callback->($status)
224 aio_link $srcpath, $dstpath, $callback->($status) 230 aio_link $srcpath, $dstpath, $callback->($status)
225 aio_symlink $srcpath, $dstpath, $callback->($status) 231 aio_symlink $srcpath, $dstpath, $callback->($status)
226 aio_readlink $path, $callback->($link) 232 aio_readlink $pathname, $callback->($link)
233 aio_realpath $pathname, $callback->($link)
227 aio_rename $srcpath, $dstpath, $callback->($status) 234 aio_rename $srcpath, $dstpath, $callback->($status)
228 aio_mkdir $pathname, $mode, $callback->($status) 235 aio_mkdir $pathname, $mode, $callback->($status)
229 aio_rmdir $pathname, $callback->($status) 236 aio_rmdir $pathname, $callback->($status)
230 aio_readdir $pathname, $callback->($entries) 237 aio_readdir $pathname, $callback->($entries)
231 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 238 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 239 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 240 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234 aio_load $path, $data, $callback->($status) 242 aio_load $pathname, $data, $callback->($status)
235 aio_copy $srcpath, $dstpath, $callback->($status) 243 aio_copy $srcpath, $dstpath, $callback->($status)
236 aio_move $srcpath, $dstpath, $callback->($status) 244 aio_move $srcpath, $dstpath, $callback->($status)
237 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238 aio_rmtree $path, $callback->($status) 245 aio_rmtree $pathname, $callback->($status)
239 aio_sync $callback->($status) 246 aio_sync $callback->($status)
247 aio_syncfs $fh, $callback->($status)
240 aio_fsync $fh, $callback->($status) 248 aio_fsync $fh, $callback->($status)
241 aio_fdatasync $fh, $callback->($status) 249 aio_fdatasync $fh, $callback->($status)
242 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 250 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243 aio_pathsync $path, $callback->($status) 251 aio_pathsync $pathname, $callback->($status)
244 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 252 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
245 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 253 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 254 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247 aio_mlockall $flags, $callback->($status) 255 aio_mlockall $flags, $callback->($status)
248 aio_group $callback->(...) 256 aio_group $callback->(...)
… …
266 IO::AIO::nready 274 IO::AIO::nready
267 IO::AIO::npending 275 IO::AIO::npending
268 276
269 IO::AIO::sendfile $ofh, $ifh, $offset, $count 277 IO::AIO::sendfile $ofh, $ifh, $offset, $count
270 IO::AIO::fadvise $fh, $offset, $len, $advice 278 IO::AIO::fadvise $fh, $offset, $len, $advice
279 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
280 IO::AIO::munmap $scalar
271 IO::AIO::madvise $scalar, $offset, $length, $advice 281 IO::AIO::madvise $scalar, $offset, $length, $advice
272 IO::AIO::mprotect $scalar, $offset, $length, $protect 282 IO::AIO::mprotect $scalar, $offset, $length, $protect
273 IO::AIO::munlock $scalar, $offset = 0, $length = undef 283 IO::AIO::munlock $scalar, $offset = 0, $length = undef
274 IO::AIO::munlockall 284 IO::AIO::munlockall
275 285
276=head2 AIO REQUEST FUNCTIONS 286=head2 API NOTES
277 287
278All the C<aio_*> calls are more or less thin wrappers around the syscall 288All the C<aio_*> calls are more or less thin wrappers around the syscall
279with the same name (sans C<aio_>). The arguments are similar or identical, 289with the same name (sans C<aio_>). The arguments are similar or identical,
280and they all accept an additional (and optional) C<$callback> argument 290and they all accept an additional (and optional) C<$callback> argument
281which must be a code reference. This code reference will get called with 291which must be a code reference. This code reference will be called after
282the syscall return code (e.g. most syscalls return C<-1> on error, unlike 292the syscall has been executed in an asynchronous fashion. The results
283perl, which usually delivers "false") as its sole argument after the given 293of the request will be passed as arguments to the callback (and, if an
284syscall has been executed asynchronously. 294error occured, in C<$!>) - for most requests the syscall return code (e.g.
295most syscalls return C<-1> on error, unlike perl, which usually delivers
296"false").
297
298Some requests (such as C<aio_readdir>) pass the actual results and
299communicate failures by passing C<undef>.
285 300
286All functions expecting a filehandle keep a copy of the filehandle 301All functions expecting a filehandle keep a copy of the filehandle
287internally until the request has finished. 302internally until the request has finished.
288 303
289All functions return request objects of type L<IO::AIO::REQ> that allow 304All functions return request objects of type L<IO::AIO::REQ> that allow
290further manipulation of those requests while they are in-flight. 305further manipulation of those requests while they are in-flight.
291 306
292The pathnames you pass to these routines I<must> be absolute and 307The pathnames you pass to these routines I<should> be absolute. The
293encoded as octets. The reason for the former is that at the time the 308reason for this is that at the time the request is being executed, the
294request is being executed, the current working directory could have 309current working directory could have changed. Alternatively, you can
295changed. Alternatively, you can make sure that you never change the 310make sure that you never change the current working directory anywhere
296current working directory anywhere in the program and then use relative 311in the program and then use relative paths. You can also take advantage
297paths. 312of IO::AIOs working directory abstraction, that lets you specify paths
313relative to some previously-opened "working directory object" - see the
314description of the C<IO::AIO::WD> class later in this document.
298 315
299To encode pathnames as octets, either make sure you either: a) always pass 316To encode pathnames as octets, either make sure you either: a) always pass
300in filenames you got from outside (command line, readdir etc.) without 317in filenames you got from outside (command line, readdir etc.) without
301tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 318tinkering, b) are in your native filesystem encoding, c) use the Encode
302your pathnames to the locale (or other) encoding in effect in the user 319module and encode your pathnames to the locale (or other) encoding in
303environment, d) use Glib::filename_from_unicode on unicode filenames or e) 320effect in the user environment, d) use Glib::filename_from_unicode on
304use something else to ensure your scalar has the correct contents. 321unicode filenames or e) use something else to ensure your scalar has the
322correct contents.
305 323
306This works, btw. independent of the internal UTF-8 bit, which IO::AIO 324This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307handles correctly whether it is set or not. 325handles correctly whether it is set or not.
326
327=head2 AIO REQUEST FUNCTIONS
308 328
309=over 4 329=over 4
310 330
311=item $prev_pri = aioreq_pri [$pri] 331=item $prev_pri = aioreq_pri [$pri]
312 332
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342 362
343 363
344=item aio_open $pathname, $flags, $mode, $callback->($fh) 364=item aio_open $pathname, $flags, $mode, $callback->($fh)
345 365
346Asynchronously open or create a file and call the callback with a newly 366Asynchronously open or create a file and call the callback with a newly
347created filehandle for the file. 367created filehandle for the file (or C<undef> in case of an error).
348 368
349The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 369The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350for an explanation. 370for an explanation.
351 371
352The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 372The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
… …
395Or in other words: the file descriptor will be closed, but it will not be 415Or in other words: the file descriptor will be closed, but it will not be
396free for reuse until the perl filehandle is closed. 416free for reuse until the perl filehandle is closed.
397 417
398=cut 418=cut
399 419
420=item aio_seek $fh, $offset, $whence, $callback->($offs)
421
422Seeks the filehandle to the new C<$offset>, similarly to perl's
423C<sysseek>. The C<$whence> can use the traditional values (C<0> for
424C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
425C<IO::AIO::SEEK_END>).
426
427The resulting absolute offset will be passed to the callback, or C<-1> in
428case of an error.
429
430In theory, the C<$whence> constants could be different than the
431corresponding values from L<Fcntl>, but perl guarantees they are the same,
432so don't panic.
433
434As a GNU/Linux (and maybe Solaris) extension, also the constants
435C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
436could be found. No guarantees about suitability for use in C<aio_seek> or
437Perl's C<sysseek> can be made though, although I would naively assume they
438"just work".
439
400=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 440=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
401 441
402=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 442=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403 443
404Reads or writes C<$length> bytes from or to the specified C<$fh> and 444Reads or writes C<$length> bytes from or to the specified C<$fh> and
… …
436 476
437Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 477Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
438reading at byte offset C<$in_offset>, and starts writing at the current 478reading at byte offset C<$in_offset>, and starts writing at the current
439file offset of C<$out_fh>. Because of that, it is not safe to issue more 479file offset of C<$out_fh>. Because of that, it is not safe to issue more
440than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 480than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
441other. 481other. The same C<$in_fh> works fine though, as this function does not
482move or use the file offset of C<$in_fh>.
442 483
443Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than 484Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
444are written, and there is no way to find out how many bytes have been read 485are written, and there is no way to find out how many more bytes have been
445from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of 486read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
446bytes written to C<$out_fh>. Only if the result value equals C<$length> 487number of bytes written to C<$out_fh>. Only if the result value equals
447one can assume that C<$length> bytes have been read. 488C<$length> one can assume that C<$length> bytes have been read.
448 489
449Unlike with other C<aio_> functions, it makes a lot of sense to use 490Unlike with other C<aio_> functions, it makes a lot of sense to use
450C<aio_sendfile> on non-blocking sockets, as long as one end (typically 491C<aio_sendfile> on non-blocking sockets, as long as one end (typically
451the C<$in_fh>) is a file - the file I/O will then be asynchronous, while 492the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
452the socket I/O will be non-blocking. Note, however, that you can run into 493the socket I/O will be non-blocking. Note, however, that you can run
453a trap where C<aio_sendfile> reads some data with readahead, then fails 494into a trap where C<aio_sendfile> reads some data with readahead, then
454to write all data, and when the socket is ready the next time, the data 495fails to write all data, and when the socket is ready the next time, the
455in the cache is already lost, forcing C<aio_sendfile> to again hit the 496data in the cache is already lost, forcing C<aio_sendfile> to again hit
456disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage 497the disk. Explicit C<aio_read> + C<aio_write> let's you better control
457much better. 498resource usage.
458 499
459This call tries to make use of a native C<sendfile> syscall to provide 500This call tries to make use of a native C<sendfile>-like syscall to
460zero-copy operation. For this to work, C<$out_fh> should refer to a 501provide zero-copy operation. For this to work, C<$out_fh> should refer to
461socket, and C<$in_fh> should refer to an mmap'able file. 502a socket, and C<$in_fh> should refer to an mmap'able file.
462 503
463If a native sendfile cannot be found or it fails with C<ENOSYS>, 504If a native sendfile cannot be found or it fails with C<ENOSYS>,
464C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>, 505C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
465it will be emulated, so you can call C<aio_sendfile> on any type of 506C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
466filehandle regardless of the limitations of the operating system. 507type of filehandle regardless of the limitations of the operating system.
508
509As native sendfile syscalls (as practically any non-POSIX interface hacked
510together in a hurry to improve benchmark numbers) tend to be rather buggy
511on many systems, this implementation tries to work around some known bugs
512in Linux and FreeBSD kernels (probably others, too), but that might fail,
513so you really really should check the return value of C<aio_sendfile> -
514fewre bytes than expected might have been transferred.
467 515
468 516
469=item aio_readahead $fh,$offset,$length, $callback->($retval) 517=item aio_readahead $fh,$offset,$length, $callback->($retval)
470 518
471C<aio_readahead> populates the page cache with data from a file so that 519C<aio_readahead> populates the page cache with data from a file so that
… …
592=item aio_truncate $fh_or_path, $offset, $callback->($status) 640=item aio_truncate $fh_or_path, $offset, $callback->($status)
593 641
594Works like truncate(2) or ftruncate(2). 642Works like truncate(2) or ftruncate(2).
595 643
596 644
645=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
646
647Allocates or freed disk space according to the C<$mode> argument. See the
648linux C<fallocate> docuemntation for details.
649
650C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE>
651to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE |
652IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range.
653
654The file system block size used by C<fallocate> is presumably the
655C<f_bsize> returned by C<statvfs>.
656
657If C<fallocate> isn't available or cannot be emulated (currently no
658emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
659
660
597=item aio_chmod $fh_or_path, $mode, $callback->($status) 661=item aio_chmod $fh_or_path, $mode, $callback->($status)
598 662
599Works like perl's C<chmod> function. 663Works like perl's C<chmod> function.
600 664
601 665
… …
603 667
604Asynchronously unlink (delete) a file and call the callback with the 668Asynchronously unlink (delete) a file and call the callback with the
605result code. 669result code.
606 670
607 671
608=item aio_mknod $path, $mode, $dev, $callback->($status) 672=item aio_mknod $pathname, $mode, $dev, $callback->($status)
609 673
610[EXPERIMENTAL] 674[EXPERIMENTAL]
611 675
612Asynchronously create a device node (or fifo). See mknod(2). 676Asynchronously create a device node (or fifo). See mknod(2).
613 677
614The only (POSIX-) portable way of calling this function is: 678The only (POSIX-) portable way of calling this function is:
615 679
616 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 680 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
617 681
618See C<aio_stat> for info about some potentially helpful extra constants 682See C<aio_stat> for info about some potentially helpful extra constants
619and functions. 683and functions.
620 684
621=item aio_link $srcpath, $dstpath, $callback->($status) 685=item aio_link $srcpath, $dstpath, $callback->($status)
… …
628 692
629Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 693Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
630the path C<$dstpath> and call the callback with the result code. 694the path C<$dstpath> and call the callback with the result code.
631 695
632 696
633=item aio_readlink $path, $callback->($link) 697=item aio_readlink $pathname, $callback->($link)
634 698
635Asynchronously read the symlink specified by C<$path> and pass it to 699Asynchronously read the symlink specified by C<$path> and pass it to
636the callback. If an error occurs, nothing or undef gets passed to the 700the callback. If an error occurs, nothing or undef gets passed to the
637callback. 701callback.
638 702
639 703
704=item aio_realpath $pathname, $callback->($path)
705
706Asynchronously make the path absolute and resolve any symlinks in
707C<$path>. The resulting path only consists of directories (Same as
708L<Cwd::realpath>).
709
710This request can be used to get the absolute path of the current working
711directory by passing it a path of F<.> (a single dot).
712
713
640=item aio_rename $srcpath, $dstpath, $callback->($status) 714=item aio_rename $srcpath, $dstpath, $callback->($status)
641 715
642Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 716Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
643rename(2) and call the callback with the result code. 717rename(2) and call the callback with the result code.
644 718
… …
666array-ref with the filenames. 740array-ref with the filenames.
667 741
668 742
669=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 743=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
670 744
671Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 745Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
672behaviour and output format. In case of an error, C<$entries> will be 746tune behaviour and output format. In case of an error, C<$entries> will be
673C<undef>. 747C<undef>.
674 748
675The flags are a combination of the following constants, ORed together (the 749The flags are a combination of the following constants, ORed together (the
676flags will also be passed to the callback, possibly modified): 750flags will also be passed to the callback, possibly modified):
677 751
… …
724 798
725=item IO::AIO::READDIR_FOUND_UNKNOWN 799=item IO::AIO::READDIR_FOUND_UNKNOWN
726 800
727This flag should not be set when calling C<aio_readdirx>. Instead, it 801This flag should not be set when calling C<aio_readdirx>. Instead, it
728is being set by C<aio_readdirx>, when any of the C<$type>'s found were 802is being set by C<aio_readdirx>, when any of the C<$type>'s found were
729C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 803C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
730C<$type>'s are known, which can be used to speed up some algorithms. 804C<$type>'s are known, which can be used to speed up some algorithms.
731 805
732=back 806=back
733 807
734 808
735=item aio_load $path, $data, $callback->($status) 809=item aio_load $pathname, $data, $callback->($status)
736 810
737This is a composite request that tries to fully load the given file into 811This is a composite request that tries to fully load the given file into
738memory. Status is the same as with aio_read. 812memory. Status is the same as with aio_read.
739 813
740=cut 814=cut
… …
862 if ($_[0] && $! == EXDEV) { 936 if ($_[0] && $! == EXDEV) {
863 aioreq_pri $pri; 937 aioreq_pri $pri;
864 add $grp aio_copy $src, $dst, sub { 938 add $grp aio_copy $src, $dst, sub {
865 $grp->result ($_[0]); 939 $grp->result ($_[0]);
866 940
867 if (!$_[0]) { 941 unless ($_[0]) {
868 aioreq_pri $pri; 942 aioreq_pri $pri;
869 add $grp aio_unlink $src; 943 add $grp aio_unlink $src;
870 } 944 }
871 }; 945 };
872 } else { 946 } else {
… …
875 }; 949 };
876 950
877 $grp 951 $grp
878} 952}
879 953
880=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 954=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
881 955
882Scans a directory (similar to C<aio_readdir>) but additionally tries to 956Scans a directory (similar to C<aio_readdir>) but additionally tries to
883efficiently separate the entries of directory C<$path> into two sets of 957efficiently separate the entries of directory C<$path> into two sets of
884names, directories you can recurse into (directories), and ones you cannot 958names, directories you can recurse into (directories), and ones you cannot
885recurse into (everything else, including symlinks to directories). 959recurse into (everything else, including symlinks to directories).
… …
916Then entries will be sorted into likely directories a non-initial dot 990Then entries will be sorted into likely directories a non-initial dot
917currently) and likely non-directories (see C<aio_readdirx>). Then every 991currently) and likely non-directories (see C<aio_readdirx>). Then every
918entry plus an appended C</.> will be C<stat>'ed, likely directories first, 992entry plus an appended C</.> will be C<stat>'ed, likely directories first,
919in order of their inode numbers. If that succeeds, it assumes that the 993in order of their inode numbers. If that succeeds, it assumes that the
920entry is a directory or a symlink to directory (which will be checked 994entry is a directory or a symlink to directory (which will be checked
921seperately). This is often faster than stat'ing the entry itself because 995separately). This is often faster than stat'ing the entry itself because
922filesystems might detect the type of the entry without reading the inode 996filesystems might detect the type of the entry without reading the inode
923data (e.g. ext2fs filetype feature), even on systems that cannot return 997data (e.g. ext2fs filetype feature), even on systems that cannot return
924the filetype information on readdir. 998the filetype information on readdir.
925 999
926If the known number of directories (link count - 2) has been reached, the 1000If the known number of directories (link count - 2) has been reached, the
… …
942 1016
943 my $grp = aio_group $cb; 1017 my $grp = aio_group $cb;
944 1018
945 $maxreq = 4 if $maxreq <= 0; 1019 $maxreq = 4 if $maxreq <= 0;
946 1020
947 # stat once 1021 # get a wd object
948 aioreq_pri $pri; 1022 aioreq_pri $pri;
949 add $grp aio_stat $path, sub { 1023 add $grp aio_wd $path, sub {
1024 $_[0]
950 return $grp->result () if $_[0]; 1025 or return $grp->result ();
951 my $now = time;
952 my $hash1 = join ":", (stat _)[0,1,3,7,9];
953 1026
954 # read the directory entries 1027 my $wd = [shift, "."];
1028
1029 # stat once
955 aioreq_pri $pri; 1030 aioreq_pri $pri;
956 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1031 add $grp aio_stat $wd, sub {
957 my $entries = shift
958 or return $grp->result (); 1032 return $grp->result () if $_[0];
1033 my $now = time;
1034 my $hash1 = join ":", (stat _)[0,1,3,7,9];
959 1035
960 # stat the dir another time 1036 # read the directory entries
961 aioreq_pri $pri; 1037 aioreq_pri $pri;
1038 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1039 my $entries = shift
1040 or return $grp->result ();
1041
1042 # stat the dir another time
1043 aioreq_pri $pri;
962 add $grp aio_stat $path, sub { 1044 add $grp aio_stat $wd, sub {
963 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1045 my $hash2 = join ":", (stat _)[0,1,3,7,9];
964 1046
965 my $ndirs; 1047 my $ndirs;
966 1048
967 # take the slow route if anything looks fishy 1049 # take the slow route if anything looks fishy
968 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1050 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
969 $ndirs = -1; 1051 $ndirs = -1;
970 } else { 1052 } else {
971 # if nlink == 2, we are finished 1053 # if nlink == 2, we are finished
972 # for non-posix-fs's, we rely on nlink < 2 1054 # for non-posix-fs's, we rely on nlink < 2
973 $ndirs = (stat _)[3] - 2 1055 $ndirs = (stat _)[3] - 2
974 or return $grp->result ([], $entries); 1056 or return $grp->result ([], $entries);
975 } 1057 }
976 1058
977 my (@dirs, @nondirs); 1059 my (@dirs, @nondirs);
978 1060
979 my $statgrp = add $grp aio_group sub { 1061 my $statgrp = add $grp aio_group sub {
980 $grp->result (\@dirs, \@nondirs); 1062 $grp->result (\@dirs, \@nondirs);
981 }; 1063 };
982 1064
983 limit $statgrp $maxreq; 1065 limit $statgrp $maxreq;
984 feed $statgrp sub { 1066 feed $statgrp sub {
985 return unless @$entries; 1067 return unless @$entries;
986 my $entry = shift @$entries; 1068 my $entry = shift @$entries;
987 1069
988 aioreq_pri $pri; 1070 aioreq_pri $pri;
1071 $wd->[1] = "$entry/.";
989 add $statgrp aio_stat "$path/$entry/.", sub { 1072 add $statgrp aio_stat $wd, sub {
990 if ($_[0] < 0) { 1073 if ($_[0] < 0) {
991 push @nondirs, $entry; 1074 push @nondirs, $entry;
992 } else { 1075 } else {
993 # need to check for real directory 1076 # need to check for real directory
994 aioreq_pri $pri; 1077 aioreq_pri $pri;
1078 $wd->[1] = $entry;
995 add $statgrp aio_lstat "$path/$entry", sub { 1079 add $statgrp aio_lstat $wd, sub {
996 if (-d _) { 1080 if (-d _) {
997 push @dirs, $entry; 1081 push @dirs, $entry;
998 1082
999 unless (--$ndirs) { 1083 unless (--$ndirs) {
1000 push @nondirs, @$entries; 1084 push @nondirs, @$entries;
1001 feed $statgrp; 1085 feed $statgrp;
1086 }
1087 } else {
1088 push @nondirs, $entry;
1002 } 1089 }
1003 } else {
1004 push @nondirs, $entry;
1005 } 1090 }
1006 } 1091 }
1007 } 1092 };
1008 }; 1093 };
1009 }; 1094 };
1010 }; 1095 };
1011 }; 1096 };
1012 }; 1097 };
1013 1098
1014 $grp 1099 $grp
1015} 1100}
1016 1101
1017=item aio_rmtree $path, $callback->($status) 1102=item aio_rmtree $pathname, $callback->($status)
1018 1103
1019Delete a directory tree starting (and including) C<$path>, return the 1104Delete a directory tree starting (and including) C<$path>, return the
1020status of the final C<rmdir> only. This is a composite request that 1105status of the final C<rmdir> only. This is a composite request that
1021uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1106uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1022everything else. 1107everything else.
… …
1064callback with the fdatasync result code. 1149callback with the fdatasync result code.
1065 1150
1066If this call isn't available because your OS lacks it or it couldn't be 1151If this call isn't available because your OS lacks it or it couldn't be
1067detected, it will be emulated by calling C<fsync> instead. 1152detected, it will be emulated by calling C<fsync> instead.
1068 1153
1154=item aio_syncfs $fh, $callback->($status)
1155
1156Asynchronously call the syncfs syscall to sync the filesystem associated
1157to the given filehandle and call the callback with the syncfs result
1158code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1159errno to C<ENOSYS> nevertheless.
1160
1069=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1161=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1070 1162
1071Sync the data portion of the file specified by C<$offset> and C<$length> 1163Sync the data portion of the file specified by C<$offset> and C<$length>
1072to disk (but NOT the metadata), by calling the Linux-specific 1164to disk (but NOT the metadata), by calling the Linux-specific
1073sync_file_range call. If sync_file_range is not available or it returns 1165sync_file_range call. If sync_file_range is not available or it returns
… …
1076C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1168C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1077C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1169C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1078C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1170C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1079manpage for details. 1171manpage for details.
1080 1172
1081=item aio_pathsync $path, $callback->($status) 1173=item aio_pathsync $pathname, $callback->($status)
1082 1174
1083This request tries to open, fsync and close the given path. This is a 1175This request tries to open, fsync and close the given path. This is a
1084composite request intended to sync directories after directory operations 1176composite request intended to sync directories after directory operations
1085(E.g. rename). This might not work on all operating systems or have any 1177(E.g. rename). This might not work on all operating systems or have any
1086specific effect, but usually it makes sure that directory changes get 1178specific effect, but usually it makes sure that directory changes get
… …
1183 1275
1184Example: asynchronously lock all current and future pages into memory. 1276Example: asynchronously lock all current and future pages into memory.
1185 1277
1186 aio_mlockall IO::AIO::MCL_FUTURE; 1278 aio_mlockall IO::AIO::MCL_FUTURE;
1187 1279
1280=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1281
1282Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
1283see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
1284C<ioctl> is not available on your OS, then this request will fail with
1285C<ENOSYS>.
1286
1287C<$start> is the starting offset to query extents for, C<$length> is the
1288size of the range to query - if it is C<undef>, then the whole file will
1289be queried.
1290
1291C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1292C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1293exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1294the data portion.
1295
1296C<$count> is the maximum number of extent records to return. If it is
1297C<undef>, then IO::AIO queries all extents of the range. As a very special
1298case, if it is C<0>, then the callback receives the number of extents
1299instead of the extents themselves (which is unreliable, see below).
1300
1301If an error occurs, the callback receives no arguments. The special
1302C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1303
1304Otherwise, the callback receives an array reference with extent
1305structures. Each extent structure is an array reference itself, with the
1306following members:
1307
1308 [$logical, $physical, $length, $flags]
1309
1310Flags is any combination of the following flag values (typically either C<0>
1311or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1312
1313C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1314C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1315C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1316C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1317C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1318C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1319
1320At the time of this writing (Linux 3.2), this requets is unreliable unless
1321C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1322it to return all extents of a range for files with large number of
1323extents. The code works around all these issues if C<$count> is undef.
1324
1188=item aio_group $callback->(...) 1325=item aio_group $callback->(...)
1189 1326
1190This is a very special aio request: Instead of doing something, it is a 1327This is a very special aio request: Instead of doing something, it is a
1191container for other aio requests, which is useful if you want to bundle 1328container for other aio requests, which is useful if you want to bundle
1192many requests into a single, composite, request with a definite callback 1329many requests into a single, composite, request with a definite callback
… …
1228like sleep and file handle readable/writable, the overhead this creates is 1365like sleep and file handle readable/writable, the overhead this creates is
1229immense (it blocks a thread for a long time) so do not use this function 1366immense (it blocks a thread for a long time) so do not use this function
1230except to put your application under artificial I/O pressure. 1367except to put your application under artificial I/O pressure.
1231 1368
1232=back 1369=back
1370
1371
1372=head2 IO::AIO::WD - multiple working directories
1373
1374Your process only has one current working directory, which is used by all
1375threads. This makes it hard to use relative paths (some other component
1376could call C<chdir> at any time, and it is hard to control when the path
1377will be used by IO::AIO).
1378
1379One solution for this is to always use absolute paths. This usually works,
1380but can be quite slow (the kernel has to walk the whole path on every
1381access), and can also be a hassle to implement.
1382
1383Newer POSIX systems have a number of functions (openat, fdopendir,
1384futimensat and so on) that make it possible to specify working directories
1385per operation.
1386
1387For portability, and because the clowns who "designed", or shall I write,
1388perpetrated this new interface were obviously half-drunk, this abstraction
1389cannot be perfect, though.
1390
1391IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1392object. This object stores the canonicalised, absolute version of the
1393path, and on systems that allow it, also a directory file descriptor.
1394
1395Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1396or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1397object and a pathname instead (or the IO::AIO::WD object alone, which
1398gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1399IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1400to that IO::AIO::WD object.
1401
1402For example, to get a wd object for F</etc> and then stat F<passwd>
1403inside, you would write:
1404
1405 aio_wd "/etc", sub {
1406 my $etcdir = shift;
1407
1408 # although $etcdir can be undef on error, there is generally no reason
1409 # to check for errors here, as aio_stat will fail with ENOENT
1410 # when $etcdir is undef.
1411
1412 aio_stat [$etcdir, "passwd"], sub {
1413 # yay
1414 };
1415 };
1416
1417That C<aio_wd> is a request and not a normal function shows that creating
1418an IO::AIO::WD object is itself a potentially blocking operation, which is
1419why it is done asynchronously.
1420
1421To stat the directory obtained with C<aio_wd> above, one could write
1422either of the following three request calls:
1423
1424 aio_lstat "/etc" , sub { ... # pathname as normal string
1425 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1426 aio_lstat $wd , sub { ... # shorthand for the previous
1427
1428As with normal pathnames, IO::AIO keeps a copy of the working directory
1429object and the pathname string, so you could write the following without
1430causing any issues due to C<$path> getting reused:
1431
1432 my $path = [$wd, undef];
1433
1434 for my $name (qw(abc def ghi)) {
1435 $path->[1] = $name;
1436 aio_stat $path, sub {
1437 # ...
1438 };
1439 }
1440
1441There are some caveats: when directories get renamed (or deleted), the
1442pathname string doesn't change, so will point to the new directory (or
1443nowhere at all), while the directory fd, if available on the system,
1444will still point to the original directory. Most functions accepting a
1445pathname will use the directory fd on newer systems, and the string on
1446older systems. Some functions (such as realpath) will always rely on the
1447string form of the pathname.
1448
1449So this fucntionality is mainly useful to get some protection against
1450C<chdir>, to easily get an absolute path out of a relative path for future
1451reference, and to speed up doing many operations in the same directory
1452(e.g. when stat'ing all files in a directory).
1453
1454The following functions implement this working directory abstraction:
1455
1456=over 4
1457
1458=item aio_wd $pathname, $callback->($wd)
1459
1460Asynchonously canonicalise the given pathname and convert it to an
1461IO::AIO::WD object representing it. If possible and supported on the
1462system, also open a directory fd to speed up pathname resolution relative
1463to this working directory.
1464
1465If something goes wrong, then C<undef> is passwd to the callback instead
1466of a working directory object and C<$!> is set appropriately. Since
1467passing C<undef> as working directory component of a pathname fails the
1468request with C<ENOENT>, there is often no need for error checking in the
1469C<aio_wd> callback, as future requests using the value will fail in the
1470expected way.
1471
1472If this call isn't available because your OS lacks it or it couldn't be
1473detected, it will be emulated by calling C<fsync> instead.
1474
1475=item IO::AIO::CWD
1476
1477This is a compiletime constant (object) that represents the process
1478current working directory.
1479
1480Specifying this object as working directory object for a pathname is as
1481if the pathname would be specified directly, without a directory object,
1482e.g., these calls are functionally identical:
1483
1484 aio_stat "somefile", sub { ... };
1485 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1486
1487=back
1488
1233 1489
1234=head2 IO::AIO::REQ CLASS 1490=head2 IO::AIO::REQ CLASS
1235 1491
1236All non-aggregate C<aio_*> functions return an object of this class when 1492All non-aggregate C<aio_*> functions return an object of this class when
1237called in non-void context. 1493called in non-void context.
… …
1355 1611
1356Sets a feeder/generator on this group: every group can have an attached 1612Sets a feeder/generator on this group: every group can have an attached
1357generator that generates requests if idle. The idea behind this is that, 1613generator that generates requests if idle. The idea behind this is that,
1358although you could just queue as many requests as you want in a group, 1614although you could just queue as many requests as you want in a group,
1359this might starve other requests for a potentially long time. For example, 1615this might starve other requests for a potentially long time. For example,
1360C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1616C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1361delaying any later requests for a long time. 1617requests, delaying any later requests for a long time.
1362 1618
1363To avoid this, and allow incremental generation of requests, you can 1619To avoid this, and allow incremental generation of requests, you can
1364instead a group and set a feeder on it that generates those requests. The 1620instead a group and set a feeder on it that generates those requests. The
1365feed callback will be called whenever there are few enough (see C<limit>, 1621feed callback will be called whenever there are few enough (see C<limit>,
1366below) requests active in the group itself and is expected to queue more 1622below) requests active in the group itself and is expected to queue more
… …
1564Sets the minimum idle timeout (default 10) after which worker threads are 1820Sets the minimum idle timeout (default 10) after which worker threads are
1565allowed to exit. SEe C<IO::AIO::max_idle>. 1821allowed to exit. SEe C<IO::AIO::max_idle>.
1566 1822
1567=item IO::AIO::max_outstanding $maxreqs 1823=item IO::AIO::max_outstanding $maxreqs
1568 1824
1825Sets the maximum number of outstanding requests to C<$nreqs>. If
1826you do queue up more than this number of requests, the next call to
1827C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1828C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1829longer exceeded.
1830
1831In other words, this setting does not enforce a queue limit, but can be
1832used to make poll functions block if the limit is exceeded.
1833
1569This is a very bad function to use in interactive programs because it 1834This is a very bad function to use in interactive programs because it
1570blocks, and a bad way to reduce concurrency because it is inexact: Better 1835blocks, and a bad way to reduce concurrency because it is inexact: Better
1571use an C<aio_group> together with a feed callback. 1836use an C<aio_group> together with a feed callback.
1572 1837
1573Sets the maximum number of outstanding requests to C<$nreqs>. If you 1838It's main use is in scripts without an event loop - when you want to stat
1574do queue up more than this number of requests, the next call to the 1839a lot of files, you can write somehting like this:
1575C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1576function will block until the limit is no longer exceeded.
1577 1840
1578The default value is very large, so there is no practical limit on the 1841 IO::AIO::max_outstanding 32;
1579number of outstanding requests.
1580 1842
1581You can still queue as many requests as you want. Therefore, 1843 for my $path (...) {
1582C<max_outstanding> is mainly useful in simple scripts (with low values) or 1844 aio_stat $path , ...;
1583as a stop gap to shield against fatal memory overflow (with large values). 1845 IO::AIO::poll_cb;
1846 }
1847
1848 IO::AIO::flush;
1849
1850The call to C<poll_cb> inside the loop will normally return instantly, but
1851as soon as more thna C<32> reqeusts are in-flight, it will block until
1852some requests have been handled. This keeps the loop from pushing a large
1853number of C<aio_stat> requests onto the queue.
1854
1855The default value for C<max_outstanding> is very large, so there is no
1856practical limit on the number of outstanding requests.
1584 1857
1585=back 1858=back
1586 1859
1587=head3 STATISTICAL INFORMATION 1860=head3 STATISTICAL INFORMATION
1588 1861
… …
1628 1901
1629=item IO::AIO::fadvise $fh, $offset, $len, $advice 1902=item IO::AIO::fadvise $fh, $offset, $len, $advice
1630 1903
1631Simply calls the C<posix_fadvise> function (see its 1904Simply calls the C<posix_fadvise> function (see its
1632manpage for details). The following advice constants are 1905manpage for details). The following advice constants are
1633avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>, 1906available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1634C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>, 1907C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1635C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>. 1908C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1636 1909
1637On systems that do not implement C<posix_fadvise>, this function returns 1910On systems that do not implement C<posix_fadvise>, this function returns
1638ENOSYS, otherwise the return value of C<posix_fadvise>. 1911ENOSYS, otherwise the return value of C<posix_fadvise>.
1639 1912
1640=item IO::AIO::madvise $scalar, $offset, $len, $advice 1913=item IO::AIO::madvise $scalar, $offset, $len, $advice
1641 1914
1642Simply calls the C<posix_madvise> function (see its 1915Simply calls the C<posix_madvise> function (see its
1643manpage for details). The following advice constants are 1916manpage for details). The following advice constants are
1644avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 1917available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1645C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 1918C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1646 1919
1647On systems that do not implement C<posix_madvise>, this function returns 1920On systems that do not implement C<posix_madvise>, this function returns
1648ENOSYS, otherwise the return value of C<posix_madvise>. 1921ENOSYS, otherwise the return value of C<posix_madvise>.
1649 1922
1650=item IO::AIO::mprotect $scalar, $offset, $len, $protect 1923=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1651 1924
1652Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 1925Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1653$scalar (see its manpage for details). The following protect 1926$scalar (see its manpage for details). The following protect
1654constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 1927constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1655C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 1928C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1656 1929
1657On systems that do not implement C<mprotect>, this function returns 1930On systems that do not implement C<mprotect>, this function returns
1658ENOSYS, otherwise the return value of C<mprotect>. 1931ENOSYS, otherwise the return value of C<mprotect>.
1659 1932
1660=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1933=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1661 1934
1662Memory-maps a file (or anonymous memory range) and attaches it to the 1935Memory-maps a file (or anonymous memory range) and attaches it to the
1663given C<$scalar>, which will act like a string scalar. 1936given C<$scalar>, which will act like a string scalar. Returns true on
1937success, and false otherwise.
1664 1938
1665The only operations allowed on the scalar are C<substr>/C<vec> that don't 1939The only operations allowed on the scalar are C<substr>/C<vec> that don't
1666change the string length, and most read-only operations such as copying it 1940change the string length, and most read-only operations such as copying it
1667or searching it with regexes and so on. 1941or searching it with regexes and so on.
1668 1942
… …
1721Calls the C<munlockall> function. 1995Calls the C<munlockall> function.
1722 1996
1723On systems that do not implement C<munlockall>, this function returns 1997On systems that do not implement C<munlockall>, this function returns
1724ENOSYS, otherwise the return value of C<munlockall>. 1998ENOSYS, otherwise the return value of C<munlockall>.
1725 1999
2000=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2001
2002Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2003C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
2004should be the file offset.
2005
2006C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2007silently corrupt the data in this case.
2008
2009The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
2010C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
2011C<IO::AIO::SPLICE_F_GIFT>.
2012
2013See the C<splice(2)> manpage for details.
2014
2015=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2016
2017Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
2018description for C<IO::AIO::splice> above for details.
2019
1726=back 2020=back
1727 2021
1728=cut 2022=cut
1729 2023
1730min_parallel 8; 2024min_parallel 8;
… …
1764 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 2058 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1765 \&IO::AIO::poll_cb); 2059 \&IO::AIO::poll_cb);
1766 2060
1767=head2 FORK BEHAVIOUR 2061=head2 FORK BEHAVIOUR
1768 2062
1769This module should do "the right thing" when the process using it forks: 2063Usage of pthreads in a program changes the semantics of fork
2064considerably. Specifically, only async-safe functions can be called after
2065fork. Perl doesn't know about this, so in general, you cannot call fork
2066with defined behaviour in perl if pthreads are involved. IO::AIO uses
2067pthreads, so this applies, but many other extensions and (for inexplicable
2068reasons) perl itself often is linked against pthreads, so this limitation
2069applies to quite a lot of perls.
1770 2070
1771Before the fork, IO::AIO enters a quiescent state where no requests 2071This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1772can be added in other threads and no results will be processed. After 2072only works in the process that loaded it. Forking is fully supported, but
1773the fork the parent simply leaves the quiescent state and continues 2073using IO::AIO in the child is not.
1774request/result processing, while the child frees the request/result queue
1775(so that the requests started before the fork will only be handled in the
1776parent). Threads will be started on demand until the limit set in the
1777parent process has been reached again.
1778 2074
1779In short: the parent will, after a short pause, continue as if fork had 2075You might get around by not I<using> IO::AIO before (or after)
1780not been called, while the child will act as if IO::AIO has not been used 2076forking. You could also try to call the L<IO::AIO::reinit> function in the
1781yet. 2077child:
2078
2079=over 4
2080
2081=item IO::AIO::reinit
2082
2083Abandons all current requests and I/O threads and simply reinitialises all
2084data structures. This is not an operation supported by any standards, but
2085happens to work on GNU/Linux and some newer BSD systems.
2086
2087The only reasonable use for this function is to call it after forking, if
2088C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
2089the process will result in undefined behaviour. Calling it at any time
2090will also result in any undefined (by POSIX) behaviour.
2091
2092=back
1782 2093
1783=head2 MEMORY USAGE 2094=head2 MEMORY USAGE
1784 2095
1785Per-request usage: 2096Per-request usage:
1786 2097

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