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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.207 by root, Mon Jul 25 16:50:33 2011 UTC vs.
Revision 1.227 by root, Tue May 29 03:58:02 2012 UTC

168use common::sense; 168use common::sense;
169 169
170use base 'Exporter'; 170use base 'Exporter';
171 171
172BEGIN { 172BEGIN {
173 our $VERSION = '4.0'; 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_realpath aio_sync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead 179 aio_pathsync aio_readahead aio_fiemap
180 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
181 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
182 aio_chmod aio_utime aio_truncate 182 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall 183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs); 184 aio_statvfs
185 aio_wd);
185 186
186 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
187 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
188 min_parallel max_parallel max_idle idle_timeout 189 min_parallel max_parallel max_idle idle_timeout
189 nreqs nready npending nthreads 190 nreqs nready npending nthreads
205 206
206This section simply lists the prototypes of the most important functions 207This section simply lists the prototypes of the most important functions
207for quick reference. See the following sections for function-by-function 208for quick reference. See the following sections for function-by-function
208documentation. 209documentation.
209 210
211 aio_wd $pathname, $callback->($wd)
210 aio_open $pathname, $flags, $mode, $callback->($fh) 212 aio_open $pathname, $flags, $mode, $callback->($fh)
211 aio_close $fh, $callback->($status) 213 aio_close $fh, $callback->($status)
214 aio_seek $fh,$offset,$whence, $callback->($offs)
212 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 215 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 216 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
214 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 217 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
215 aio_readahead $fh,$offset,$length, $callback->($retval) 218 aio_readahead $fh,$offset,$length, $callback->($retval)
216 aio_stat $fh_or_path, $callback->($status) 219 aio_stat $fh_or_path, $callback->($status)
217 aio_lstat $fh, $callback->($status) 220 aio_lstat $fh, $callback->($status)
218 aio_statvfs $fh_or_path, $callback->($statvfs) 221 aio_statvfs $fh_or_path, $callback->($statvfs)
219 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
220 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)
221 aio_truncate $fh_or_path, $offset, $callback->($status) 225 aio_truncate $fh_or_path, $offset, $callback->($status)
222 aio_chmod $fh_or_path, $mode, $callback->($status)
223 aio_unlink $pathname, $callback->($status) 226 aio_unlink $pathname, $callback->($status)
224 aio_mknod $path, $mode, $dev, $callback->($status) 227 aio_mknod $pathname, $mode, $dev, $callback->($status)
225 aio_link $srcpath, $dstpath, $callback->($status) 228 aio_link $srcpath, $dstpath, $callback->($status)
226 aio_symlink $srcpath, $dstpath, $callback->($status) 229 aio_symlink $srcpath, $dstpath, $callback->($status)
227 aio_readlink $path, $callback->($link) 230 aio_readlink $pathname, $callback->($link)
228 aio_realpath $path, $callback->($link) 231 aio_realpath $pathname, $callback->($link)
229 aio_rename $srcpath, $dstpath, $callback->($status) 232 aio_rename $srcpath, $dstpath, $callback->($status)
230 aio_mkdir $pathname, $mode, $callback->($status) 233 aio_mkdir $pathname, $mode, $callback->($status)
231 aio_rmdir $pathname, $callback->($status) 234 aio_rmdir $pathname, $callback->($status)
232 aio_readdir $pathname, $callback->($entries) 235 aio_readdir $pathname, $callback->($entries)
233 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 236 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
234 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 237 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
235 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 238 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
236 aio_load $path, $data, $callback->($status) 240 aio_load $pathname, $data, $callback->($status)
237 aio_copy $srcpath, $dstpath, $callback->($status) 241 aio_copy $srcpath, $dstpath, $callback->($status)
238 aio_move $srcpath, $dstpath, $callback->($status) 242 aio_move $srcpath, $dstpath, $callback->($status)
239 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
240 aio_rmtree $path, $callback->($status) 243 aio_rmtree $pathname, $callback->($status)
241 aio_sync $callback->($status) 244 aio_sync $callback->($status)
242 aio_syncfs $fh, $callback->($status) 245 aio_syncfs $fh, $callback->($status)
243 aio_fsync $fh, $callback->($status) 246 aio_fsync $fh, $callback->($status)
244 aio_fdatasync $fh, $callback->($status) 247 aio_fdatasync $fh, $callback->($status)
245 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
246 aio_pathsync $path, $callback->($status) 249 aio_pathsync $pathname, $callback->($status)
247 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
248 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
249 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
250 aio_mlockall $flags, $callback->($status) 253 aio_mlockall $flags, $callback->($status)
251 aio_group $callback->(...) 254 aio_group $callback->(...)
269 IO::AIO::nready 272 IO::AIO::nready
270 IO::AIO::npending 273 IO::AIO::npending
271 274
272 IO::AIO::sendfile $ofh, $ifh, $offset, $count 275 IO::AIO::sendfile $ofh, $ifh, $offset, $count
273 IO::AIO::fadvise $fh, $offset, $len, $advice 276 IO::AIO::fadvise $fh, $offset, $len, $advice
277 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
278 IO::AIO::munmap $scalar
274 IO::AIO::madvise $scalar, $offset, $length, $advice 279 IO::AIO::madvise $scalar, $offset, $length, $advice
275 IO::AIO::mprotect $scalar, $offset, $length, $protect 280 IO::AIO::mprotect $scalar, $offset, $length, $protect
276 IO::AIO::munlock $scalar, $offset = 0, $length = undef 281 IO::AIO::munlock $scalar, $offset = 0, $length = undef
277 IO::AIO::munlockall 282 IO::AIO::munlockall
278 283
279=head2 AIO REQUEST FUNCTIONS 284=head2 API NOTES
280 285
281All the C<aio_*> calls are more or less thin wrappers around the syscall 286All the C<aio_*> calls are more or less thin wrappers around the syscall
282with the same name (sans C<aio_>). The arguments are similar or identical, 287with the same name (sans C<aio_>). The arguments are similar or identical,
283and they all accept an additional (and optional) C<$callback> argument 288and they all accept an additional (and optional) C<$callback> argument
284which must be a code reference. This code reference will get called with 289which must be a code reference. This code reference will be called after
285the syscall return code (e.g. most syscalls return C<-1> on error, unlike 290the syscall has been executed in an asynchronous fashion. The results
286perl, which usually delivers "false") as its sole argument after the given 291of the request will be passed as arguments to the callback (and, if an
287syscall has been executed asynchronously. 292error occured, in C<$!>) - for most requests the syscall return code (e.g.
293most syscalls return C<-1> on error, unlike perl, which usually delivers
294"false").
295
296Some requests (such as C<aio_readdir>) pass the actual results and
297communicate failures by passing C<undef>.
288 298
289All functions expecting a filehandle keep a copy of the filehandle 299All functions expecting a filehandle keep a copy of the filehandle
290internally until the request has finished. 300internally until the request has finished.
291 301
292All functions return request objects of type L<IO::AIO::REQ> that allow 302All functions return request objects of type L<IO::AIO::REQ> that allow
293further manipulation of those requests while they are in-flight. 303further manipulation of those requests while they are in-flight.
294 304
295The pathnames you pass to these routines I<must> be absolute and 305The pathnames you pass to these routines I<should> be absolute. The
296encoded as octets. The reason for the former is that at the time the 306reason for this is that at the time the request is being executed, the
297request is being executed, the current working directory could have 307current working directory could have changed. Alternatively, you can
298changed. Alternatively, you can make sure that you never change the 308make sure that you never change the current working directory anywhere
299current working directory anywhere in the program and then use relative 309in the program and then use relative paths. You can also take advantage
300paths. 310of IO::AIOs working directory abstraction, that lets you specify paths
311relative to some previously-opened "working directory object" - see the
312description of the C<IO::AIO::WD> class later in this document.
301 313
302To encode pathnames as octets, either make sure you either: a) always pass 314To encode pathnames as octets, either make sure you either: a) always pass
303in filenames you got from outside (command line, readdir etc.) without 315in filenames you got from outside (command line, readdir etc.) without
304tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 316tinkering, b) are in your native filesystem encoding, c) use the Encode
305your pathnames to the locale (or other) encoding in effect in the user 317module and encode your pathnames to the locale (or other) encoding in
306environment, d) use Glib::filename_from_unicode on unicode filenames or e) 318effect in the user environment, d) use Glib::filename_from_unicode on
307use something else to ensure your scalar has the correct contents. 319unicode filenames or e) use something else to ensure your scalar has the
320correct contents.
308 321
309This works, btw. independent of the internal UTF-8 bit, which IO::AIO 322This works, btw. independent of the internal UTF-8 bit, which IO::AIO
310handles correctly whether it is set or not. 323handles correctly whether it is set or not.
324
325=head2 AIO REQUEST FUNCTIONS
311 326
312=over 4 327=over 4
313 328
314=item $prev_pri = aioreq_pri [$pri] 329=item $prev_pri = aioreq_pri [$pri]
315 330
397 412
398Or in other words: the file descriptor will be closed, but it will not be 413Or in other words: the file descriptor will be closed, but it will not be
399free for reuse until the perl filehandle is closed. 414free for reuse until the perl filehandle is closed.
400 415
401=cut 416=cut
417
418=item aio_seek $fh, $offset, $whence, $callback->($offs)
419
420Seeks the filehandle to the new C<$offset>, similarly to perl's
421C<sysseek>. The C<$whence> can use the traditional values (C<0> for
422C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
423C<IO::AIO::SEEK_END>).
424
425The resulting absolute offset will be passed to the callback, or C<-1> in
426case of an error.
427
428In theory, the C<$whence> constants could be different than the
429corresponding values from L<Fcntl>, but perl guarantees they are the same,
430so don't panic.
431
432As a GNU/Linux (and maybe Solaris) extension, also the constants
433C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
434could be found. No guarantees about suitability for use in C<aio_seek> or
435Perl's C<sysseek> can be made though, although I would naively assume they
436"just work".
402 437
403=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 438=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
404 439
405=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 440=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
406 441
614 649
615Asynchronously unlink (delete) a file and call the callback with the 650Asynchronously unlink (delete) a file and call the callback with the
616result code. 651result code.
617 652
618 653
619=item aio_mknod $path, $mode, $dev, $callback->($status) 654=item aio_mknod $pathname, $mode, $dev, $callback->($status)
620 655
621[EXPERIMENTAL] 656[EXPERIMENTAL]
622 657
623Asynchronously create a device node (or fifo). See mknod(2). 658Asynchronously create a device node (or fifo). See mknod(2).
624 659
625The only (POSIX-) portable way of calling this function is: 660The only (POSIX-) portable way of calling this function is:
626 661
627 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 662 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
628 663
629See C<aio_stat> for info about some potentially helpful extra constants 664See C<aio_stat> for info about some potentially helpful extra constants
630and functions. 665and functions.
631 666
632=item aio_link $srcpath, $dstpath, $callback->($status) 667=item aio_link $srcpath, $dstpath, $callback->($status)
639 674
640Asynchronously create a new symbolic link to the existing object at C<$srcpath> at 675Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
641the path C<$dstpath> and call the callback with the result code. 676the path C<$dstpath> and call the callback with the result code.
642 677
643 678
644=item aio_readlink $path, $callback->($link) 679=item aio_readlink $pathname, $callback->($link)
645 680
646Asynchronously read the symlink specified by C<$path> and pass it to 681Asynchronously read the symlink specified by C<$path> and pass it to
647the callback. If an error occurs, nothing or undef gets passed to the 682the callback. If an error occurs, nothing or undef gets passed to the
648callback. 683callback.
649 684
650 685
651=item aio_realpath $path, $callback->($path) 686=item aio_realpath $pathname, $callback->($path)
652 687
653Asynchronously make the path absolute and resolve any symlinks in 688Asynchronously make the path absolute and resolve any symlinks in
654C<$path>. The resulting path only consists of directories (Same as 689C<$path>. The resulting path only consists of directories (Same as
655L<Cwd::realpath>). 690L<Cwd::realpath>).
656 691
751C<$type>'s are known, which can be used to speed up some algorithms. 786C<$type>'s are known, which can be used to speed up some algorithms.
752 787
753=back 788=back
754 789
755 790
756=item aio_load $path, $data, $callback->($status) 791=item aio_load $pathname, $data, $callback->($status)
757 792
758This is a composite request that tries to fully load the given file into 793This is a composite request that tries to fully load the given file into
759memory. Status is the same as with aio_read. 794memory. Status is the same as with aio_read.
760 795
761=cut 796=cut
896 }; 931 };
897 932
898 $grp 933 $grp
899} 934}
900 935
901=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 936=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
902 937
903Scans a directory (similar to C<aio_readdir>) but additionally tries to 938Scans a directory (similar to C<aio_readdir>) but additionally tries to
904efficiently separate the entries of directory C<$path> into two sets of 939efficiently separate the entries of directory C<$path> into two sets of
905names, directories you can recurse into (directories), and ones you cannot 940names, directories you can recurse into (directories), and ones you cannot
906recurse into (everything else, including symlinks to directories). 941recurse into (everything else, including symlinks to directories).
963 998
964 my $grp = aio_group $cb; 999 my $grp = aio_group $cb;
965 1000
966 $maxreq = 4 if $maxreq <= 0; 1001 $maxreq = 4 if $maxreq <= 0;
967 1002
968 # stat once 1003 # get a wd object
969 aioreq_pri $pri; 1004 aioreq_pri $pri;
970 add $grp aio_stat $path, sub { 1005 add $grp aio_wd $path, sub {
1006 $_[0]
971 return $grp->result () if $_[0]; 1007 or return $grp->result ();
972 my $now = time;
973 my $hash1 = join ":", (stat _)[0,1,3,7,9];
974 1008
975 # read the directory entries 1009 my $wd = [shift, "."];
1010
1011 # stat once
976 aioreq_pri $pri; 1012 aioreq_pri $pri;
977 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1013 add $grp aio_stat $wd, sub {
978 my $entries = shift
979 or return $grp->result (); 1014 return $grp->result () if $_[0];
1015 my $now = time;
1016 my $hash1 = join ":", (stat _)[0,1,3,7,9];
980 1017
981 # stat the dir another time 1018 # read the directory entries
982 aioreq_pri $pri; 1019 aioreq_pri $pri;
1020 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1021 my $entries = shift
1022 or return $grp->result ();
1023
1024 # stat the dir another time
1025 aioreq_pri $pri;
983 add $grp aio_stat $path, sub { 1026 add $grp aio_stat $wd, sub {
984 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1027 my $hash2 = join ":", (stat _)[0,1,3,7,9];
985 1028
986 my $ndirs; 1029 my $ndirs;
987 1030
988 # take the slow route if anything looks fishy 1031 # take the slow route if anything looks fishy
989 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1032 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
990 $ndirs = -1; 1033 $ndirs = -1;
991 } else { 1034 } else {
992 # if nlink == 2, we are finished 1035 # if nlink == 2, we are finished
993 # for non-posix-fs's, we rely on nlink < 2 1036 # for non-posix-fs's, we rely on nlink < 2
994 $ndirs = (stat _)[3] - 2 1037 $ndirs = (stat _)[3] - 2
995 or return $grp->result ([], $entries); 1038 or return $grp->result ([], $entries);
996 } 1039 }
997 1040
998 my (@dirs, @nondirs); 1041 my (@dirs, @nondirs);
999 1042
1000 my $statgrp = add $grp aio_group sub { 1043 my $statgrp = add $grp aio_group sub {
1001 $grp->result (\@dirs, \@nondirs); 1044 $grp->result (\@dirs, \@nondirs);
1002 }; 1045 };
1003 1046
1004 limit $statgrp $maxreq; 1047 limit $statgrp $maxreq;
1005 feed $statgrp sub { 1048 feed $statgrp sub {
1006 return unless @$entries; 1049 return unless @$entries;
1007 my $entry = shift @$entries; 1050 my $entry = shift @$entries;
1008 1051
1009 aioreq_pri $pri; 1052 aioreq_pri $pri;
1053 $wd->[1] = "$entry/.";
1010 add $statgrp aio_stat "$path/$entry/.", sub { 1054 add $statgrp aio_stat $wd, sub {
1011 if ($_[0] < 0) { 1055 if ($_[0] < 0) {
1012 push @nondirs, $entry; 1056 push @nondirs, $entry;
1013 } else { 1057 } else {
1014 # need to check for real directory 1058 # need to check for real directory
1015 aioreq_pri $pri; 1059 aioreq_pri $pri;
1060 $wd->[1] = $entry;
1016 add $statgrp aio_lstat "$path/$entry", sub { 1061 add $statgrp aio_lstat $wd, sub {
1017 if (-d _) { 1062 if (-d _) {
1018 push @dirs, $entry; 1063 push @dirs, $entry;
1019 1064
1020 unless (--$ndirs) { 1065 unless (--$ndirs) {
1021 push @nondirs, @$entries; 1066 push @nondirs, @$entries;
1022 feed $statgrp; 1067 feed $statgrp;
1068 }
1069 } else {
1070 push @nondirs, $entry;
1023 } 1071 }
1024 } else {
1025 push @nondirs, $entry;
1026 } 1072 }
1027 } 1073 }
1028 } 1074 };
1029 }; 1075 };
1030 }; 1076 };
1031 }; 1077 };
1032 }; 1078 };
1033 }; 1079 };
1034 1080
1035 $grp 1081 $grp
1036} 1082}
1037 1083
1038=item aio_rmtree $path, $callback->($status) 1084=item aio_rmtree $pathname, $callback->($status)
1039 1085
1040Delete a directory tree starting (and including) C<$path>, return the 1086Delete a directory tree starting (and including) C<$path>, return the
1041status of the final C<rmdir> only. This is a composite request that 1087status of the final C<rmdir> only. This is a composite request that
1042uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1088uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1043everything else. 1089everything else.
1104C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>, 1150C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1105C<IO::AIO::SYNC_FILE_RANGE_WRITE> and 1151C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1106C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range 1152C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1107manpage for details. 1153manpage for details.
1108 1154
1109=item aio_pathsync $path, $callback->($status) 1155=item aio_pathsync $pathname, $callback->($status)
1110 1156
1111This request tries to open, fsync and close the given path. This is a 1157This request tries to open, fsync and close the given path. This is a
1112composite request intended to sync directories after directory operations 1158composite request intended to sync directories after directory operations
1113(E.g. rename). This might not work on all operating systems or have any 1159(E.g. rename). This might not work on all operating systems or have any
1114specific effect, but usually it makes sure that directory changes get 1160specific effect, but usually it makes sure that directory changes get
1211 1257
1212Example: asynchronously lock all current and future pages into memory. 1258Example: asynchronously lock all current and future pages into memory.
1213 1259
1214 aio_mlockall IO::AIO::MCL_FUTURE; 1260 aio_mlockall IO::AIO::MCL_FUTURE;
1215 1261
1262=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1263
1264Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
1265see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
1266C<ioctl> is not available on your OS, then this rquiest will fail with
1267C<ENOSYS>.
1268
1269C<$start> is the starting offset to query extents for, C<$length> is the
1270size of the range to query - if it is C<undef>, then the whole file will
1271be queried.
1272
1273C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1274C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1275exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1276the data portion.
1277
1278C<$count> is the maximum number of extent records to return. If it is
1279C<undef>, then IO::AIO queries all extents of the file. As a very special
1280case, if it is C<0>, then the callback receives the number of extents
1281instead of the extents themselves.
1282
1283If an error occurs, the callback receives no arguments. The special
1284C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1285
1286Otherwise, the callback receives an array reference with extent
1287structures. Each extent structure is an array reference itself, with the
1288following members:
1289
1290 [$logical, $physical, $length, $flags]
1291
1292Flags is any combination of the following flag values (typically either C<0>
1293or C<IO::AIO::FIEMAP_EXTENT_LAST>):
1294
1295C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1296C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1297C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1298C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1299C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1300C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1301
1216=item aio_group $callback->(...) 1302=item aio_group $callback->(...)
1217 1303
1218This is a very special aio request: Instead of doing something, it is a 1304This is a very special aio request: Instead of doing something, it is a
1219container for other aio requests, which is useful if you want to bundle 1305container for other aio requests, which is useful if you want to bundle
1220many requests into a single, composite, request with a definite callback 1306many requests into a single, composite, request with a definite callback
1256like sleep and file handle readable/writable, the overhead this creates is 1342like sleep and file handle readable/writable, the overhead this creates is
1257immense (it blocks a thread for a long time) so do not use this function 1343immense (it blocks a thread for a long time) so do not use this function
1258except to put your application under artificial I/O pressure. 1344except to put your application under artificial I/O pressure.
1259 1345
1260=back 1346=back
1347
1348
1349=head2 IO::AIO::WD - multiple working directories
1350
1351Your process only has one current working directory, which is used by all
1352threads. This makes it hard to use relative paths (some other component
1353could call C<chdir> at any time, and it is hard to control when the path
1354will be used by IO::AIO).
1355
1356One solution for this is to always use absolute paths. This usually works,
1357but can be quite slow (the kernel has to walk the whole path on every
1358access), and can also be a hassle to implement.
1359
1360Newer POSIX systems have a number of functions (openat, fdopendir,
1361futimensat and so on) that make it possible to specify working directories
1362per operation.
1363
1364For portability, and because the clowns who "designed", or shall I write,
1365perpetrated this new interface were obviously half-drunk, this abstraction
1366cannot be perfect, though.
1367
1368IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
1369object. This object stores the canonicalised, absolute version of the
1370path, and on systems that allow it, also a directory file descriptor.
1371
1372Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1373or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1374object and a pathname instead (or the IO::AIO::WD object alone, which
1375gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1376IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1377to that IO::AIO::WD object.
1378
1379For example, to get a wd object for F</etc> and then stat F<passwd>
1380inside, you would write:
1381
1382 aio_wd "/etc", sub {
1383 my $etcdir = shift;
1384
1385 # although $etcdir can be undef on error, there is generally no reason
1386 # to check for errors here, as aio_stat will fail with ENOENT
1387 # when $etcdir is undef.
1388
1389 aio_stat [$etcdir, "passwd"], sub {
1390 # yay
1391 };
1392 };
1393
1394That C<aio_wd> is a request and not a normal function shows that creating
1395an IO::AIO::WD object is itself a potentially blocking operation, which is
1396why it is done asynchronously.
1397
1398To stat the directory obtained with C<aio_wd> above, one could write
1399either of the following three request calls:
1400
1401 aio_lstat "/etc" , sub { ... # pathname as normal string
1402 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1403 aio_lstat $wd , sub { ... # shorthand for the previous
1404
1405As with normal pathnames, IO::AIO keeps a copy of the working directory
1406object and the pathname string, so you could write the following without
1407causing any issues due to C<$path> getting reused:
1408
1409 my $path = [$wd, undef];
1410
1411 for my $name (qw(abc def ghi)) {
1412 $path->[1] = $name;
1413 aio_stat $path, sub {
1414 # ...
1415 };
1416 }
1417
1418There are some caveats: when directories get renamed (or deleted), the
1419pathname string doesn't change, so will point to the new directory (or
1420nowhere at all), while the directory fd, if available on the system,
1421will still point to the original directory. Most functions accepting a
1422pathname will use the directory fd on newer systems, and the string on
1423older systems. Some functions (such as realpath) will always rely on the
1424string form of the pathname.
1425
1426So this fucntionality is mainly useful to get some protection against
1427C<chdir>, to easily get an absolute path out of a relative path for future
1428reference, and to speed up doing many operations in the same directory
1429(e.g. when stat'ing all files in a directory).
1430
1431The following functions implement this working directory abstraction:
1432
1433=over 4
1434
1435=item aio_wd $pathname, $callback->($wd)
1436
1437Asynchonously canonicalise the given pathname and convert it to an
1438IO::AIO::WD object representing it. If possible and supported on the
1439system, also open a directory fd to speed up pathname resolution relative
1440to this working directory.
1441
1442If something goes wrong, then C<undef> is passwd to the callback instead
1443of a working directory object and C<$!> is set appropriately. Since
1444passing C<undef> as working directory component of a pathname fails the
1445request with C<ENOENT>, there is often no need for error checking in the
1446C<aio_wd> callback, as future requests using the value will fail in the
1447expected way.
1448
1449If this call isn't available because your OS lacks it or it couldn't be
1450detected, it will be emulated by calling C<fsync> instead.
1451
1452=item IO::AIO::CWD
1453
1454This is a compiletime constant (object) that represents the process
1455current working directory.
1456
1457Specifying this object as working directory object for a pathname is as
1458if the pathname would be specified directly, without a directory object,
1459e.g., these calls are functionally identical:
1460
1461 aio_stat "somefile", sub { ... };
1462 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1463
1464=back
1465
1261 1466
1262=head2 IO::AIO::REQ CLASS 1467=head2 IO::AIO::REQ CLASS
1263 1468
1264All non-aggregate C<aio_*> functions return an object of this class when 1469All non-aggregate C<aio_*> functions return an object of this class when
1265called in non-void context. 1470called in non-void context.
1383 1588
1384Sets a feeder/generator on this group: every group can have an attached 1589Sets a feeder/generator on this group: every group can have an attached
1385generator that generates requests if idle. The idea behind this is that, 1590generator that generates requests if idle. The idea behind this is that,
1386although you could just queue as many requests as you want in a group, 1591although you could just queue as many requests as you want in a group,
1387this might starve other requests for a potentially long time. For example, 1592this might starve other requests for a potentially long time. For example,
1388C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1593C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1389delaying any later requests for a long time. 1594requests, delaying any later requests for a long time.
1390 1595
1391To avoid this, and allow incremental generation of requests, you can 1596To avoid this, and allow incremental generation of requests, you can
1392instead a group and set a feeder on it that generates those requests. The 1597instead a group and set a feeder on it that generates those requests. The
1393feed callback will be called whenever there are few enough (see C<limit>, 1598feed callback will be called whenever there are few enough (see C<limit>,
1394below) requests active in the group itself and is expected to queue more 1599below) requests active in the group itself and is expected to queue more
1766Calls the C<munlockall> function. 1971Calls the C<munlockall> function.
1767 1972
1768On systems that do not implement C<munlockall>, this function returns 1973On systems that do not implement C<munlockall>, this function returns
1769ENOSYS, otherwise the return value of C<munlockall>. 1974ENOSYS, otherwise the return value of C<munlockall>.
1770 1975
1976=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1977
1978Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
1979C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
1980should be the file offset.
1981
1982C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
1983silently corrupt the data in this case.
1984
1985The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
1986C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
1987C<IO::AIO::SPLICE_F_GIFT>.
1988
1989See the C<splice(2)> manpage for details.
1990
1991=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
1992
1993Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
1994description for C<IO::AIO::splice> above for details.
1995
1771=back 1996=back
1772 1997
1773=cut 1998=cut
1774 1999
1775min_parallel 8; 2000min_parallel 8;

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