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150 QUICK OVERVIEW 150 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 151 This section simply lists the prototypes of the most important functions
152 for quick reference. See the following sections for function-by-function 152 for quick reference. See the following sections for function-by-function
153 documentation. 153 documentation.
154 154
155 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 156 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 157 aio_close $fh, $callback->($status)
158 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 159 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 160 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 161 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 162 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 163 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 164 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 165 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 166 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 167 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
168 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 169 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
168 aio_unlink $pathname, $callback->($status) 170 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 171 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 172 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 173 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 174 aio_readlink $pathname, $callback->($link)
173 aio_realpath $path, $callback->($link) 175 aio_realpath $pathname, $callback->($link)
174 aio_rename $srcpath, $dstpath, $callback->($status) 176 aio_rename $srcpath, $dstpath, $callback->($status)
175 aio_mkdir $pathname, $mode, $callback->($status) 177 aio_mkdir $pathname, $mode, $callback->($status)
176 aio_rmdir $pathname, $callback->($status) 178 aio_rmdir $pathname, $callback->($status)
177 aio_readdir $pathname, $callback->($entries) 179 aio_readdir $pathname, $callback->($entries)
178 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 180 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
179 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 181 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
180 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 182 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
183 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
181 aio_load $path, $data, $callback->($status) 184 aio_load $pathname, $data, $callback->($status)
182 aio_copy $srcpath, $dstpath, $callback->($status) 185 aio_copy $srcpath, $dstpath, $callback->($status)
183 aio_move $srcpath, $dstpath, $callback->($status) 186 aio_move $srcpath, $dstpath, $callback->($status)
184 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
185 aio_rmtree $path, $callback->($status) 187 aio_rmtree $pathname, $callback->($status)
186 aio_sync $callback->($status) 188 aio_sync $callback->($status)
189 aio_syncfs $fh, $callback->($status)
187 aio_fsync $fh, $callback->($status) 190 aio_fsync $fh, $callback->($status)
188 aio_fdatasync $fh, $callback->($status) 191 aio_fdatasync $fh, $callback->($status)
189 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 192 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
190 aio_pathsync $path, $callback->($status) 193 aio_pathsync $pathname, $callback->($status)
191 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 194 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 195 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
193 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 196 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
194 aio_mlockall $flags, $callback->($status) 197 aio_mlockall $flags, $callback->($status)
195 aio_group $callback->(...) 198 aio_group $callback->(...)
218 IO::AIO::madvise $scalar, $offset, $length, $advice 221 IO::AIO::madvise $scalar, $offset, $length, $advice
219 IO::AIO::mprotect $scalar, $offset, $length, $protect 222 IO::AIO::mprotect $scalar, $offset, $length, $protect
220 IO::AIO::munlock $scalar, $offset = 0, $length = undef 223 IO::AIO::munlock $scalar, $offset = 0, $length = undef
221 IO::AIO::munlockall 224 IO::AIO::munlockall
222 225
223 AIO REQUEST FUNCTIONS 226 API NOTES
224 All the "aio_*" calls are more or less thin wrappers around the syscall 227 All the "aio_*" calls are more or less thin wrappers around the syscall
225 with the same name (sans "aio_"). The arguments are similar or 228 with the same name (sans "aio_"). The arguments are similar or
226 identical, and they all accept an additional (and optional) $callback 229 identical, and they all accept an additional (and optional) $callback
227 argument which must be a code reference. This code reference will get 230 argument which must be a code reference. This code reference will be
228 called with the syscall return code (e.g. most syscalls return -1 on
229 error, unlike perl, which usually delivers "false") as its sole argument
230 after the given syscall has been executed asynchronously. 231 called after the syscall has been executed in an asynchronous fashion.
232 The results of the request will be passed as arguments to the callback
233 (and, if an error occured, in $!) - for most requests the syscall return
234 code (e.g. most syscalls return -1 on error, unlike perl, which usually
235 delivers "false").
236
237 Some requests (such as "aio_readdir") pass the actual results and
238 communicate failures by passing "undef".
231 239
232 All functions expecting a filehandle keep a copy of the filehandle 240 All functions expecting a filehandle keep a copy of the filehandle
233 internally until the request has finished. 241 internally until the request has finished.
234 242
235 All functions return request objects of type IO::AIO::REQ that allow 243 All functions return request objects of type IO::AIO::REQ that allow
236 further manipulation of those requests while they are in-flight. 244 further manipulation of those requests while they are in-flight.
237 245
238 The pathnames you pass to these routines *must* be absolute and encoded 246 The pathnames you pass to these routines *should* be absolute. The
239 as octets. The reason for the former is that at the time the request is 247 reason for this is that at the time the request is being executed, the
240 being executed, the current working directory could have changed. 248 current working directory could have changed. Alternatively, you can
241 Alternatively, you can make sure that you never change the current 249 make sure that you never change the current working directory anywhere
242 working directory anywhere in the program and then use relative paths. 250 in the program and then use relative paths. You can also take advantage
251 of IO::AIOs working directory abstraction, that lets you specify paths
252 relative to some previously-opened "working directory object" - see the
253 description of the "IO::AIO::WD" class later in this document.
243 254
244 To encode pathnames as octets, either make sure you either: a) always 255 To encode pathnames as octets, either make sure you either: a) always
245 pass in filenames you got from outside (command line, readdir etc.) 256 pass in filenames you got from outside (command line, readdir etc.)
246 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 257 without tinkering, b) are in your native filesystem encoding, c) use the
247 and encode your pathnames to the locale (or other) encoding in effect in 258 Encode module and encode your pathnames to the locale (or other)
248 the user environment, d) use Glib::filename_from_unicode on unicode 259 encoding in effect in the user environment, d) use
249 filenames or e) use something else to ensure your scalar has the correct 260 Glib::filename_from_unicode on unicode filenames or e) use something
250 contents. 261 else to ensure your scalar has the correct contents.
251 262
252 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 263 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
253 handles correctly whether it is set or not. 264 handles correctly whether it is set or not.
254 265
266 AIO REQUEST FUNCTIONS
255 $prev_pri = aioreq_pri [$pri] 267 $prev_pri = aioreq_pri [$pri]
256 Returns the priority value that would be used for the next request 268 Returns the priority value that would be used for the next request
257 and, if $pri is given, sets the priority for the next aio request. 269 and, if $pri is given, sets the priority for the next aio request.
258 270
259 The default priority is 0, the minimum and maximum priorities are -4 271 The default priority is 0, the minimum and maximum priorities are -4
330 will use dup2 to overwrite the file descriptor with the write-end of 342 will use dup2 to overwrite the file descriptor with the write-end of
331 a pipe (the pipe fd will be created on demand and will be cached). 343 a pipe (the pipe fd will be created on demand and will be cached).
332 344
333 Or in other words: the file descriptor will be closed, but it will 345 Or in other words: the file descriptor will be closed, but it will
334 not be free for reuse until the perl filehandle is closed. 346 not be free for reuse until the perl filehandle is closed.
347
348 aio_seek $fh, $offset, $whence, $callback->($offs)
349 Seeks the filehandle to the new $offset, similarly to perl's
350 "sysseek". The $whence can use the traditional values (0 for
351 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
352 "IO::AIO::SEEK_END").
353
354 The resulting absolute offset will be passed to the callback, or -1
355 in case of an error.
356
357 In theory, the $whence constants could be different than the
358 corresponding values from Fcntl, but perl guarantees they are the
359 same, so don't panic.
360
361 As a GNU/Linux (and maybe Solaris) extension, also the constants
362 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
363 could be found. No guarantees about suitability for use in
364 "aio_seek" or Perl's "sysseek" can be made though, although I would
365 naively assume they "just work".
335 366
336 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 367 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
337 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 368 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
338 Reads or writes $length bytes from or to the specified $fh and 369 Reads or writes $length bytes from or to the specified $fh and
339 $offset into the scalar given by $data and offset $dataoffset and 370 $offset into the scalar given by $data and offset $dataoffset and
532 563
533 aio_unlink $pathname, $callback->($status) 564 aio_unlink $pathname, $callback->($status)
534 Asynchronously unlink (delete) a file and call the callback with the 565 Asynchronously unlink (delete) a file and call the callback with the
535 result code. 566 result code.
536 567
537 aio_mknod $path, $mode, $dev, $callback->($status) 568 aio_mknod $pathname, $mode, $dev, $callback->($status)
538 [EXPERIMENTAL] 569 [EXPERIMENTAL]
539 570
540 Asynchronously create a device node (or fifo). See mknod(2). 571 Asynchronously create a device node (or fifo). See mknod(2).
541 572
542 The only (POSIX-) portable way of calling this function is: 573 The only (POSIX-) portable way of calling this function is:
543 574
544 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 575 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
545 576
546 See "aio_stat" for info about some potentially helpful extra 577 See "aio_stat" for info about some potentially helpful extra
547 constants and functions. 578 constants and functions.
548 579
549 aio_link $srcpath, $dstpath, $callback->($status) 580 aio_link $srcpath, $dstpath, $callback->($status)
553 aio_symlink $srcpath, $dstpath, $callback->($status) 584 aio_symlink $srcpath, $dstpath, $callback->($status)
554 Asynchronously create a new symbolic link to the existing object at 585 Asynchronously create a new symbolic link to the existing object at
555 $srcpath at the path $dstpath and call the callback with the result 586 $srcpath at the path $dstpath and call the callback with the result
556 code. 587 code.
557 588
558 aio_readlink $path, $callback->($link) 589 aio_readlink $pathname, $callback->($link)
559 Asynchronously read the symlink specified by $path and pass it to 590 Asynchronously read the symlink specified by $path and pass it to
560 the callback. If an error occurs, nothing or undef gets passed to 591 the callback. If an error occurs, nothing or undef gets passed to
561 the callback. 592 the callback.
562 593
563 aio_realpath $path, $callback->($path) 594 aio_realpath $pathname, $callback->($path)
564 Asynchronously make the path absolute and resolve any symlinks in 595 Asynchronously make the path absolute and resolve any symlinks in
565 $path. The resulting path only consists of directories (Same as 596 $path. The resulting path only consists of directories (Same as
566 Cwd::realpath). 597 Cwd::realpath).
567 598
568 This request can be used to get the absolute path of the current 599 This request can be used to get the absolute path of the current
588 619
589 The callback is passed a single argument which is either "undef" or 620 The callback is passed a single argument which is either "undef" or
590 an array-ref with the filenames. 621 an array-ref with the filenames.
591 622
592 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 623 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
593 Quite similar to "aio_readdir", but the $flags argument allows to 624 Quite similar to "aio_readdir", but the $flags argument allows one
594 tune behaviour and output format. In case of an error, $entries will 625 to tune behaviour and output format. In case of an error, $entries
595 be "undef". 626 will be "undef".
596 627
597 The flags are a combination of the following constants, ORed 628 The flags are a combination of the following constants, ORed
598 together (the flags will also be passed to the callback, possibly 629 together (the flags will also be passed to the callback, possibly
599 modified): 630 modified):
600 631
645 optimal stat order. 676 optimal stat order.
646 677
647 IO::AIO::READDIR_FOUND_UNKNOWN 678 IO::AIO::READDIR_FOUND_UNKNOWN
648 This flag should not be set when calling "aio_readdirx". 679 This flag should not be set when calling "aio_readdirx".
649 Instead, it is being set by "aio_readdirx", when any of the 680 Instead, it is being set by "aio_readdirx", when any of the
650 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 681 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
651 flag therefore indicates that all $type's are known, which can 682 flag therefore indicates that all $type's are known, which can
652 be used to speed up some algorithms. 683 be used to speed up some algorithms.
653 684
654 aio_load $path, $data, $callback->($status) 685 aio_load $pathname, $data, $callback->($status)
655 This is a composite request that tries to fully load the given file 686 This is a composite request that tries to fully load the given file
656 into memory. Status is the same as with aio_read. 687 into memory. Status is the same as with aio_read.
657 688
658 aio_copy $srcpath, $dstpath, $callback->($status) 689 aio_copy $srcpath, $dstpath, $callback->($status)
659 Try to copy the *file* (directories not supported as either source 690 Try to copy the *file* (directories not supported as either source
676 707
677 This is a composite request that tries to rename(2) the file first; 708 This is a composite request that tries to rename(2) the file first;
678 if rename fails with "EXDEV", it copies the file with "aio_copy" 709 if rename fails with "EXDEV", it copies the file with "aio_copy"
679 and, if that is successful, unlinks the $srcpath. 710 and, if that is successful, unlinks the $srcpath.
680 711
681 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 712 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
682 Scans a directory (similar to "aio_readdir") but additionally tries 713 Scans a directory (similar to "aio_readdir") but additionally tries
683 to efficiently separate the entries of directory $path into two sets 714 to efficiently separate the entries of directory $path into two sets
684 of names, directories you can recurse into (directories), and ones 715 of names, directories you can recurse into (directories), and ones
685 you cannot recurse into (everything else, including symlinks to 716 you cannot recurse into (everything else, including symlinks to
686 directories). 717 directories).
719 Then entries will be sorted into likely directories a non-initial 750 Then entries will be sorted into likely directories a non-initial
720 dot currently) and likely non-directories (see "aio_readdirx"). Then 751 dot currently) and likely non-directories (see "aio_readdirx"). Then
721 every entry plus an appended "/." will be "stat"'ed, likely 752 every entry plus an appended "/." will be "stat"'ed, likely
722 directories first, in order of their inode numbers. If that 753 directories first, in order of their inode numbers. If that
723 succeeds, it assumes that the entry is a directory or a symlink to 754 succeeds, it assumes that the entry is a directory or a symlink to
724 directory (which will be checked seperately). This is often faster 755 directory (which will be checked separately). This is often faster
725 than stat'ing the entry itself because filesystems might detect the 756 than stat'ing the entry itself because filesystems might detect the
726 type of the entry without reading the inode data (e.g. ext2fs 757 type of the entry without reading the inode data (e.g. ext2fs
727 filetype feature), even on systems that cannot return the filetype 758 filetype feature), even on systems that cannot return the filetype
728 information on readdir. 759 information on readdir.
729 760
735 766
736 It will also likely work on non-POSIX filesystems with reduced 767 It will also likely work on non-POSIX filesystems with reduced
737 efficiency as those tend to return 0 or 1 as link counts, which 768 efficiency as those tend to return 0 or 1 as link counts, which
738 disables the directory counting heuristic. 769 disables the directory counting heuristic.
739 770
740 aio_rmtree $path, $callback->($status) 771 aio_rmtree $pathname, $callback->($status)
741 Delete a directory tree starting (and including) $path, return the 772 Delete a directory tree starting (and including) $path, return the
742 status of the final "rmdir" only. This is a composite request that 773 status of the final "rmdir" only. This is a composite request that
743 uses "aio_scandir" to recurse into and rmdir directories, and unlink 774 uses "aio_scandir" to recurse into and rmdir directories, and unlink
744 everything else. 775 everything else.
745 776
754 Asynchronously call fdatasync on the given filehandle and call the 785 Asynchronously call fdatasync on the given filehandle and call the
755 callback with the fdatasync result code. 786 callback with the fdatasync result code.
756 787
757 If this call isn't available because your OS lacks it or it couldn't 788 If this call isn't available because your OS lacks it or it couldn't
758 be detected, it will be emulated by calling "fsync" instead. 789 be detected, it will be emulated by calling "fsync" instead.
790
791 aio_syncfs $fh, $callback->($status)
792 Asynchronously call the syncfs syscall to sync the filesystem
793 associated to the given filehandle and call the callback with the
794 syncfs result code. If syncfs is not available, calls sync(), but
795 returns -1 and sets errno to "ENOSYS" nevertheless.
759 796
760 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 797 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
761 Sync the data portion of the file specified by $offset and $length 798 Sync the data portion of the file specified by $offset and $length
762 to disk (but NOT the metadata), by calling the Linux-specific 799 to disk (but NOT the metadata), by calling the Linux-specific
763 sync_file_range call. If sync_file_range is not available or it 800 sync_file_range call. If sync_file_range is not available or it
767 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 804 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
768 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 805 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
769 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 806 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
770 manpage for details. 807 manpage for details.
771 808
772 aio_pathsync $path, $callback->($status) 809 aio_pathsync $pathname, $callback->($status)
773 This request tries to open, fsync and close the given path. This is 810 This request tries to open, fsync and close the given path. This is
774 a composite request intended to sync directories after directory 811 a composite request intended to sync directories after directory
775 operations (E.g. rename). This might not work on all operating 812 operations (E.g. rename). This might not work on all operating
776 systems or have any specific effect, but usually it makes sure that 813 systems or have any specific effect, but usually it makes sure that
777 directory changes get written to disc. It works for anything that 814 directory changes get written to disc. It works for anything that
847 Example: asynchronously lock all current and future pages into 884 Example: asynchronously lock all current and future pages into
848 memory. 885 memory.
849 886
850 aio_mlockall IO::AIO::MCL_FUTURE; 887 aio_mlockall IO::AIO::MCL_FUTURE;
851 888
889 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
890 Queries the extents of the given file (by calling the Linux FIEMAP
891 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
892 details). If the "ioctl" is not available on your OS, then this
893 rquiest will fail with "ENOSYS".
894
895 $start is the starting offset to query extents for, $length is the
896 size of the range to query - if it is "undef", then the whole file
897 will be queried.
898
899 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
900 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
901 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
902 query the data portion.
903
904 $count is the maximum number of extent records to return. If it is
905 "undef", then IO::AIO queries all extents of the file. As a very
906 special case, if it is 0, then the callback receives the number of
907 extents instead of the extents themselves.
908
909 If an error occurs, the callback receives no arguments. The special
910 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
911
912 Otherwise, the callback receives an array reference with extent
913 structures. Each extent structure is an array reference itself, with
914 the following members:
915
916 [$logical, $physical, $length, $flags]
917
918 Flags is any combination of the following flag values (typically
919 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST"):
920
921 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
922 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
923 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
924 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
925 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
926 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
927 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
928 or "IO::AIO::FIEMAP_EXTENT_SHARED".
929
852 aio_group $callback->(...) 930 aio_group $callback->(...)
853 This is a very special aio request: Instead of doing something, it 931 This is a very special aio request: Instead of doing something, it
854 is a container for other aio requests, which is useful if you want 932 is a container for other aio requests, which is useful if you want
855 to bundle many requests into a single, composite, request with a 933 to bundle many requests into a single, composite, request with a
856 definite callback and the ability to cancel the whole request with 934 definite callback and the ability to cancel the whole request with
889 While it is theoretically handy to have simple I/O scheduling 967 While it is theoretically handy to have simple I/O scheduling
890 requests like sleep and file handle readable/writable, the overhead 968 requests like sleep and file handle readable/writable, the overhead
891 this creates is immense (it blocks a thread for a long time) so do 969 this creates is immense (it blocks a thread for a long time) so do
892 not use this function except to put your application under 970 not use this function except to put your application under
893 artificial I/O pressure. 971 artificial I/O pressure.
972
973 IO::AIO::WD - multiple working directories
974 Your process only has one current working directory, which is used by
975 all threads. This makes it hard to use relative paths (some other
976 component could call "chdir" at any time, and it is hard to control when
977 the path will be used by IO::AIO).
978
979 One solution for this is to always use absolute paths. This usually
980 works, but can be quite slow (the kernel has to walk the whole path on
981 every access), and can also be a hassle to implement.
982
983 Newer POSIX systems have a number of functions (openat, fdopendir,
984 futimensat and so on) that make it possible to specify working
985 directories per operation.
986
987 For portability, and because the clowns who "designed", or shall I
988 write, perpetrated this new interface were obviously half-drunk, this
989 abstraction cannot be perfect, though.
990
991 IO::AIO allows you to convert directory paths into a so-called
992 IO::AIO::WD object. This object stores the canonicalised, absolute
993 version of the path, and on systems that allow it, also a directory file
994 descriptor.
995
996 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
997 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
998 object and a pathname instead (or the IO::AIO::WD object alone, which
999 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1000 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1001 relative to that IO::AIO::WD object.
1002
1003 For example, to get a wd object for /etc and then stat passwd inside,
1004 you would write:
1005
1006 aio_wd "/etc", sub {
1007 my $etcdir = shift;
1008
1009 # although $etcdir can be undef on error, there is generally no reason
1010 # to check for errors here, as aio_stat will fail with ENOENT
1011 # when $etcdir is undef.
1012
1013 aio_stat [$etcdir, "passwd"], sub {
1014 # yay
1015 };
1016 };
1017
1018 That "aio_wd" is a request and not a normal function shows that creating
1019 an IO::AIO::WD object is itself a potentially blocking operation, which
1020 is why it is done asynchronously.
1021
1022 To stat the directory obtained with "aio_wd" above, one could write
1023 either of the following three request calls:
1024
1025 aio_lstat "/etc" , sub { ... # pathname as normal string
1026 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1027 aio_lstat $wd , sub { ... # shorthand for the previous
1028
1029 As with normal pathnames, IO::AIO keeps a copy of the working directory
1030 object and the pathname string, so you could write the following without
1031 causing any issues due to $path getting reused:
1032
1033 my $path = [$wd, undef];
1034
1035 for my $name (qw(abc def ghi)) {
1036 $path->[1] = $name;
1037 aio_stat $path, sub {
1038 # ...
1039 };
1040 }
1041
1042 There are some caveats: when directories get renamed (or deleted), the
1043 pathname string doesn't change, so will point to the new directory (or
1044 nowhere at all), while the directory fd, if available on the system,
1045 will still point to the original directory. Most functions accepting a
1046 pathname will use the directory fd on newer systems, and the string on
1047 older systems. Some functions (such as realpath) will always rely on the
1048 string form of the pathname.
1049
1050 So this fucntionality is mainly useful to get some protection against
1051 "chdir", to easily get an absolute path out of a relative path for
1052 future reference, and to speed up doing many operations in the same
1053 directory (e.g. when stat'ing all files in a directory).
1054
1055 The following functions implement this working directory abstraction:
1056
1057 aio_wd $pathname, $callback->($wd)
1058 Asynchonously canonicalise the given pathname and convert it to an
1059 IO::AIO::WD object representing it. If possible and supported on the
1060 system, also open a directory fd to speed up pathname resolution
1061 relative to this working directory.
1062
1063 If something goes wrong, then "undef" is passwd to the callback
1064 instead of a working directory object and $! is set appropriately.
1065 Since passing "undef" as working directory component of a pathname
1066 fails the request with "ENOENT", there is often no need for error
1067 checking in the "aio_wd" callback, as future requests using the
1068 value will fail in the expected way.
1069
1070 If this call isn't available because your OS lacks it or it couldn't
1071 be detected, it will be emulated by calling "fsync" instead.
1072
1073 IO::AIO::CWD
1074 This is a compiletime constant (object) that represents the process
1075 current working directory.
1076
1077 Specifying this object as working directory object for a pathname is
1078 as if the pathname would be specified directly, without a directory
1079 object, e.g., these calls are functionally identical:
1080
1081 aio_stat "somefile", sub { ... };
1082 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
894 1083
895 IO::AIO::REQ CLASS 1084 IO::AIO::REQ CLASS
896 All non-aggregate "aio_*" functions return an object of this class when 1085 All non-aggregate "aio_*" functions return an object of this class when
897 called in non-void context. 1086 called in non-void context.
898 1087
998 Sets a feeder/generator on this group: every group can have an 1187 Sets a feeder/generator on this group: every group can have an
999 attached generator that generates requests if idle. The idea behind 1188 attached generator that generates requests if idle. The idea behind
1000 this is that, although you could just queue as many requests as you 1189 this is that, although you could just queue as many requests as you
1001 want in a group, this might starve other requests for a potentially 1190 want in a group, this might starve other requests for a potentially
1002 long time. For example, "aio_scandir" might generate hundreds of 1191 long time. For example, "aio_scandir" might generate hundreds of
1003 thousands "aio_stat" requests, delaying any later requests for a 1192 thousands of "aio_stat" requests, delaying any later requests for a
1004 long time. 1193 long time.
1005 1194
1006 To avoid this, and allow incremental generation of requests, you can 1195 To avoid this, and allow incremental generation of requests, you can
1007 instead a group and set a feeder on it that generates those 1196 instead a group and set a feeder on it that generates those
1008 requests. The feed callback will be called whenever there are few 1197 requests. The feed callback will be called whenever there are few
1256 1445
1257 Returns the number of bytes copied, or -1 on error. 1446 Returns the number of bytes copied, or -1 on error.
1258 1447
1259 IO::AIO::fadvise $fh, $offset, $len, $advice 1448 IO::AIO::fadvise $fh, $offset, $len, $advice
1260 Simply calls the "posix_fadvise" function (see its manpage for 1449 Simply calls the "posix_fadvise" function (see its manpage for
1261 details). The following advice constants are avaiable: 1450 details). The following advice constants are available:
1262 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1451 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1263 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1452 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1264 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1453 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1265 1454
1266 On systems that do not implement "posix_fadvise", this function 1455 On systems that do not implement "posix_fadvise", this function
1267 returns ENOSYS, otherwise the return value of "posix_fadvise". 1456 returns ENOSYS, otherwise the return value of "posix_fadvise".
1268 1457
1269 IO::AIO::madvise $scalar, $offset, $len, $advice 1458 IO::AIO::madvise $scalar, $offset, $len, $advice
1270 Simply calls the "posix_madvise" function (see its manpage for 1459 Simply calls the "posix_madvise" function (see its manpage for
1271 details). The following advice constants are avaiable: 1460 details). The following advice constants are available:
1272 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1461 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1273 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1462 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1274 "IO::AIO::MADV_DONTNEED". 1463 "IO::AIO::MADV_DONTNEED".
1275 1464
1276 On systems that do not implement "posix_madvise", this function 1465 On systems that do not implement "posix_madvise", this function
1277 returns ENOSYS, otherwise the return value of "posix_madvise". 1466 returns ENOSYS, otherwise the return value of "posix_madvise".
1278 1467
1279 IO::AIO::mprotect $scalar, $offset, $len, $protect 1468 IO::AIO::mprotect $scalar, $offset, $len, $protect
1280 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1469 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1281 $scalar (see its manpage for details). The following protect 1470 $scalar (see its manpage for details). The following protect
1282 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1471 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1283 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1472 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1284 1473
1285 On systems that do not implement "mprotect", this function returns 1474 On systems that do not implement "mprotect", this function returns
1286 ENOSYS, otherwise the return value of "mprotect". 1475 ENOSYS, otherwise the return value of "mprotect".
1287 1476
1345 IO::AIO::munlockall 1534 IO::AIO::munlockall
1346 Calls the "munlockall" function. 1535 Calls the "munlockall" function.
1347 1536
1348 On systems that do not implement "munlockall", this function returns 1537 On systems that do not implement "munlockall", this function returns
1349 ENOSYS, otherwise the return value of "munlockall". 1538 ENOSYS, otherwise the return value of "munlockall".
1539
1540 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1541 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1542 $w_off are "undef", then "NULL" is passed for these, otherwise they
1543 should be the file offset.
1544
1545 The following symbol flag values are available:
1546 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1547 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1548
1549 See the splice(2) manpage for details.
1550
1551 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1552 Calls the GNU/Linux tee(2) syscall, see it's manpage and the
1553 description for "IO::AIO::splice" above for details.
1350 1554
1351EVENT LOOP INTEGRATION 1555EVENT LOOP INTEGRATION
1352 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1556 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1353 automatically into many event loops: 1557 automatically into many event loops:
1354 1558
1393 1597
1394 You might get around by not *using* IO::AIO before (or after) forking. 1598 You might get around by not *using* IO::AIO before (or after) forking.
1395 You could also try to call the IO::AIO::reinit function in the child: 1599 You could also try to call the IO::AIO::reinit function in the child:
1396 1600
1397 IO::AIO::reinit 1601 IO::AIO::reinit
1398 Abondons all current requests and I/O threads and simply 1602 Abandons all current requests and I/O threads and simply
1399 reinitialises all data structures. This is not an operation 1603 reinitialises all data structures. This is not an operation
1400 suppported by any standards, but happens to work on GNU/Linux and 1604 supported by any standards, but happens to work on GNU/Linux and
1401 some newer BSD systems. 1605 some newer BSD systems.
1402 1606
1403 The only reasonable use for this function is to call it after 1607 The only reasonable use for this function is to call it after
1404 forking, if "IO::AIO" was used in the parent. Calling it while 1608 forking, if "IO::AIO" was used in the parent. Calling it while
1405 IO::AIO is active in the process will result in undefined behaviour. 1609 IO::AIO is active in the process will result in undefined behaviour.

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