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Revision 1.50 by root, Sun Oct 9 08:24:49 2011 UTC vs.
Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC

64 64
65 EXAMPLE 65 EXAMPLE
66 This is a simple example that uses the EV module and loads /etc/passwd 66 This is a simple example that uses the EV module and loads /etc/passwd
67 asynchronously: 67 asynchronously:
68 68
69 use Fcntl;
70 use EV; 69 use EV;
71 use IO::AIO; 70 use IO::AIO;
72 71
73 # register the IO::AIO callback with EV 72 # register the IO::AIO callback with EV
74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 73 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
91 90
92 # file contents now in $contents 91 # file contents now in $contents
93 print $contents; 92 print $contents;
94 93
95 # exit event loop and program 94 # exit event loop and program
96 EV::unloop; 95 EV::break;
97 }; 96 };
98 }; 97 };
99 98
100 # possibly queue up other requests, or open GUI windows, 99 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 100 # check for sockets etc. etc.
102 101
103 # process events as long as there are some: 102 # process events as long as there are some:
104 EV::loop; 103 EV::run;
105 104
106REQUEST ANATOMY AND LIFETIME 105REQUEST ANATOMY AND LIFETIME
107 Every "aio_*" function creates a request. which is a C data structure 106 Every "aio_*" function creates a request. which is a C data structure
108 not directly visible to Perl. 107 not directly visible to Perl.
109 108
146 the actual aio request is severed and calling its methods will 145 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 146 either do nothing or result in a runtime error).
148 147
149FUNCTIONS 148FUNCTIONS
150 QUICK OVERVIEW 149 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 150 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 151 reference. See the following sections for function-by-function
153 documentation. 152 documentation.
154 153
155 aio_wd $pathname, $callback->($wd) 154 aio_wd $pathname, $callback->($wd)
156 aio_open $pathname, $flags, $mode, $callback->($fh) 155 aio_open $pathname, $flags, $mode, $callback->($fh)
157 aio_close $fh, $callback->($status) 156 aio_close $fh, $callback->($status)
157 aio_seek $fh,$offset,$whence, $callback->($offs)
158 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 158 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 159 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
160 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 160 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
161 aio_readahead $fh,$offset,$length, $callback->($retval) 161 aio_readahead $fh,$offset,$length, $callback->($retval)
162 aio_stat $fh_or_path, $callback->($status) 162 aio_stat $fh_or_path, $callback->($status)
163 aio_lstat $fh, $callback->($status) 163 aio_lstat $fh, $callback->($status)
164 aio_statvfs $fh_or_path, $callback->($statvfs) 164 aio_statvfs $fh_or_path, $callback->($statvfs)
165 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 165 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
166 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 166 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
167 aio_truncate $fh_or_path, $offset, $callback->($status) 168 aio_truncate $fh_or_path, $offset, $callback->($status)
168 aio_chmod $fh_or_path, $mode, $callback->($status) 169 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
170 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
169 aio_unlink $pathname, $callback->($status) 171 aio_unlink $pathname, $callback->($status)
170 aio_mknod $pathname, $mode, $dev, $callback->($status) 172 aio_mknod $pathname, $mode, $dev, $callback->($status)
171 aio_link $srcpath, $dstpath, $callback->($status) 173 aio_link $srcpath, $dstpath, $callback->($status)
172 aio_symlink $srcpath, $dstpath, $callback->($status) 174 aio_symlink $srcpath, $dstpath, $callback->($status)
173 aio_readlink $pathname, $callback->($link) 175 aio_readlink $pathname, $callback->($link)
174 aio_realpath $pathname, $callback->($link) 176 aio_realpath $pathname, $callback->($path)
175 aio_rename $srcpath, $dstpath, $callback->($status) 177 aio_rename $srcpath, $dstpath, $callback->($status)
176 aio_mkdir $pathname, $mode, $callback->($status) 178 aio_mkdir $pathname, $mode, $callback->($status)
177 aio_rmdir $pathname, $callback->($status) 179 aio_rmdir $pathname, $callback->($status)
178 aio_readdir $pathname, $callback->($entries) 180 aio_readdir $pathname, $callback->($entries)
179 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 181 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
182 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
183 aio_load $pathname, $data, $callback->($status) 185 aio_load $pathname, $data, $callback->($status)
184 aio_copy $srcpath, $dstpath, $callback->($status) 186 aio_copy $srcpath, $dstpath, $callback->($status)
185 aio_move $srcpath, $dstpath, $callback->($status) 187 aio_move $srcpath, $dstpath, $callback->($status)
186 aio_rmtree $pathname, $callback->($status) 188 aio_rmtree $pathname, $callback->($status)
189 aio_fcntl $fh, $cmd, $arg, $callback->($status)
190 aio_ioctl $fh, $request, $buf, $callback->($status)
187 aio_sync $callback->($status) 191 aio_sync $callback->($status)
188 aio_syncfs $fh, $callback->($status) 192 aio_syncfs $fh, $callback->($status)
189 aio_fsync $fh, $callback->($status) 193 aio_fsync $fh, $callback->($status)
190 aio_fdatasync $fh, $callback->($status) 194 aio_fdatasync $fh, $callback->($status)
191 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 195 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
215 IO::AIO::nready 219 IO::AIO::nready
216 IO::AIO::npending 220 IO::AIO::npending
217 221
218 IO::AIO::sendfile $ofh, $ifh, $offset, $count 222 IO::AIO::sendfile $ofh, $ifh, $offset, $count
219 IO::AIO::fadvise $fh, $offset, $len, $advice 223 IO::AIO::fadvise $fh, $offset, $len, $advice
224 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
225 IO::AIO::munmap $scalar
220 IO::AIO::madvise $scalar, $offset, $length, $advice 226 IO::AIO::madvise $scalar, $offset, $length, $advice
221 IO::AIO::mprotect $scalar, $offset, $length, $protect 227 IO::AIO::mprotect $scalar, $offset, $length, $protect
222 IO::AIO::munlock $scalar, $offset = 0, $length = undef 228 IO::AIO::munlock $scalar, $offset = 0, $length = undef
223 IO::AIO::munlockall 229 IO::AIO::munlockall
224 230
225 AIO REQUEST FUNCTIONS 231 API NOTES
226 All the "aio_*" calls are more or less thin wrappers around the syscall 232 All the "aio_*" calls are more or less thin wrappers around the syscall
227 with the same name (sans "aio_"). The arguments are similar or 233 with the same name (sans "aio_"). The arguments are similar or
228 identical, and they all accept an additional (and optional) $callback 234 identical, and they all accept an additional (and optional) $callback
229 argument which must be a code reference. This code reference will be 235 argument which must be a code reference. This code reference will be
230 called after the syscall has been executed in an asynchronous fashion. 236 called after the syscall has been executed in an asynchronous fashion.
260 else to ensure your scalar has the correct contents. 266 else to ensure your scalar has the correct contents.
261 267
262 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 268 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
263 handles correctly whether it is set or not. 269 handles correctly whether it is set or not.
264 270
271 AIO REQUEST FUNCTIONS
265 $prev_pri = aioreq_pri [$pri] 272 $prev_pri = aioreq_pri [$pri]
266 Returns the priority value that would be used for the next request 273 Returns the priority value that would be used for the next request
267 and, if $pri is given, sets the priority for the next aio request. 274 and, if $pri is given, sets the priority for the next aio request.
268 275
269 The default priority is 0, the minimum and maximum priorities are -4 276 The default priority is 0, the minimum and maximum priorities are -4
291 Similar to "aioreq_pri", but subtracts the given value from the 298 Similar to "aioreq_pri", but subtracts the given value from the
292 current priority, so the effect is cumulative. 299 current priority, so the effect is cumulative.
293 300
294 aio_open $pathname, $flags, $mode, $callback->($fh) 301 aio_open $pathname, $flags, $mode, $callback->($fh)
295 Asynchronously open or create a file and call the callback with a 302 Asynchronously open or create a file and call the callback with a
296 newly created filehandle for the file. 303 newly created filehandle for the file (or "undef" in case of an
304 error).
297 305
298 The pathname passed to "aio_open" must be absolute. See API NOTES, 306 The pathname passed to "aio_open" must be absolute. See API NOTES,
299 above, for an explanation. 307 above, for an explanation.
300 308
301 The $flags argument is a bitmask. See the "Fcntl" module for a list. 309 The $flags argument is a bitmask. See the "Fcntl" module for a list.
324 "O_APPEND"), the following POSIX and non-POSIX constants are 332 "O_APPEND"), the following POSIX and non-POSIX constants are
325 available (missing ones on your system are, as usual, 0): 333 available (missing ones on your system are, as usual, 0):
326 334
327 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 335 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
328 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 336 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
329 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". 337 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and
338 "O_TTY_INIT".
330 339
331 aio_close $fh, $callback->($status) 340 aio_close $fh, $callback->($status)
332 Asynchronously close a file and call the callback with the result 341 Asynchronously close a file and call the callback with the result
333 code. 342 code.
334 343
340 will use dup2 to overwrite the file descriptor with the write-end of 349 will use dup2 to overwrite the file descriptor with the write-end of
341 a pipe (the pipe fd will be created on demand and will be cached). 350 a pipe (the pipe fd will be created on demand and will be cached).
342 351
343 Or in other words: the file descriptor will be closed, but it will 352 Or in other words: the file descriptor will be closed, but it will
344 not be free for reuse until the perl filehandle is closed. 353 not be free for reuse until the perl filehandle is closed.
354
355 aio_seek $fh, $offset, $whence, $callback->($offs)
356 Seeks the filehandle to the new $offset, similarly to perl's
357 "sysseek". The $whence can use the traditional values (0 for
358 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
359 "IO::AIO::SEEK_END").
360
361 The resulting absolute offset will be passed to the callback, or -1
362 in case of an error.
363
364 In theory, the $whence constants could be different than the
365 corresponding values from Fcntl, but perl guarantees they are the
366 same, so don't panic.
367
368 As a GNU/Linux (and maybe Solaris) extension, also the constants
369 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
370 could be found. No guarantees about suitability for use in
371 "aio_seek" or Perl's "sysseek" can be made though, although I would
372 naively assume they "just work".
345 373
346 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
347 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
348 Reads or writes $length bytes from or to the specified $fh and 376 Reads or writes $length bytes from or to the specified $fh and
349 $offset into the scalar given by $data and offset $dataoffset and 377 $offset into the scalar given by $data and offset $dataoffset and
504 namemax => 255, 532 namemax => 255,
505 frsize => 1024, 533 frsize => 1024,
506 fsid => 1810 534 fsid => 1810
507 } 535 }
508 536
537 Here is a (likely partial - send me updates!) list of fsid values
538 used by Linux - it is safe to hardcode these when $^O is "linux":
539
540 0x0000adf5 adfs
541 0x0000adff affs
542 0x5346414f afs
543 0x09041934 anon-inode filesystem
544 0x00000187 autofs
545 0x42465331 befs
546 0x1badface bfs
547 0x42494e4d binfmt_misc
548 0x9123683e btrfs
549 0x0027e0eb cgroupfs
550 0xff534d42 cifs
551 0x73757245 coda
552 0x012ff7b7 coh
553 0x28cd3d45 cramfs
554 0x453dcd28 cramfs-wend (wrong endianness)
555 0x64626720 debugfs
556 0x00001373 devfs
557 0x00001cd1 devpts
558 0x0000f15f ecryptfs
559 0x00414a53 efs
560 0x0000137d ext
561 0x0000ef53 ext2/ext3/ext4
562 0x0000ef51 ext2
563 0xf2f52010 f2fs
564 0x00004006 fat
565 0x65735546 fuseblk
566 0x65735543 fusectl
567 0x0bad1dea futexfs
568 0x01161970 gfs2
569 0x47504653 gpfs
570 0x00004244 hfs
571 0xf995e849 hpfs
572 0x00c0ffee hostfs
573 0x958458f6 hugetlbfs
574 0x2bad1dea inotifyfs
575 0x00009660 isofs
576 0x000072b6 jffs2
577 0x3153464a jfs
578 0x6b414653 k-afs
579 0x0bd00bd0 lustre
580 0x0000137f minix
581 0x0000138f minix 30 char names
582 0x00002468 minix v2
583 0x00002478 minix v2 30 char names
584 0x00004d5a minix v3
585 0x19800202 mqueue
586 0x00004d44 msdos
587 0x0000564c novell
588 0x00006969 nfs
589 0x6e667364 nfsd
590 0x00003434 nilfs
591 0x5346544e ntfs
592 0x00009fa1 openprom
593 0x7461636F ocfs2
594 0x00009fa0 proc
595 0x6165676c pstorefs
596 0x0000002f qnx4
597 0x68191122 qnx6
598 0x858458f6 ramfs
599 0x52654973 reiserfs
600 0x00007275 romfs
601 0x67596969 rpc_pipefs
602 0x73636673 securityfs
603 0xf97cff8c selinux
604 0x0000517b smb
605 0x534f434b sockfs
606 0x73717368 squashfs
607 0x62656572 sysfs
608 0x012ff7b6 sysv2
609 0x012ff7b5 sysv4
610 0x01021994 tmpfs
611 0x15013346 udf
612 0x00011954 ufs
613 0x54190100 ufs byteswapped
614 0x00009fa2 usbdevfs
615 0x01021997 v9fs
616 0xa501fcf5 vxfs
617 0xabba1974 xenfs
618 0x012ff7b4 xenix
619 0x58465342 xfs
620 0x012fd16d xia
621
509 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 622 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
510 Works like perl's "utime" function (including the special case of 623 Works like perl's "utime" function (including the special case of
511 $atime and $mtime being undef). Fractional times are supported if 624 $atime and $mtime being undef). Fractional times are supported if
512 the underlying syscalls support them. 625 the underlying syscalls support them.
513 626
535 aio_chown "path", 0, undef; 648 aio_chown "path", 0, undef;
536 649
537 aio_truncate $fh_or_path, $offset, $callback->($status) 650 aio_truncate $fh_or_path, $offset, $callback->($status)
538 Works like truncate(2) or ftruncate(2). 651 Works like truncate(2) or ftruncate(2).
539 652
653 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
654 Allocates or frees disk space according to the $mode argument. See
655 the linux "fallocate" documentation for details.
656
657 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
658 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
659 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
660
661 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
662 (without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range
663 (see your fallocate(2) manpage).
664
665 The file system block size used by "fallocate" is presumably the
666 "f_bsize" returned by "statvfs".
667
668 If "fallocate" isn't available or cannot be emulated (currently no
669 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
670
540 aio_chmod $fh_or_path, $mode, $callback->($status) 671 aio_chmod $fh_or_path, $mode, $callback->($status)
541 Works like perl's "chmod" function. 672 Works like perl's "chmod" function.
542 673
543 aio_unlink $pathname, $callback->($status) 674 aio_unlink $pathname, $callback->($status)
544 Asynchronously unlink (delete) a file and call the callback with the 675 Asynchronously unlink (delete) a file and call the callback with the
570 the callback. If an error occurs, nothing or undef gets passed to 701 the callback. If an error occurs, nothing or undef gets passed to
571 the callback. 702 the callback.
572 703
573 aio_realpath $pathname, $callback->($path) 704 aio_realpath $pathname, $callback->($path)
574 Asynchronously make the path absolute and resolve any symlinks in 705 Asynchronously make the path absolute and resolve any symlinks in
575 $path. The resulting path only consists of directories (Same as 706 $path. The resulting path only consists of directories (same as
576 Cwd::realpath). 707 Cwd::realpath).
577 708
578 This request can be used to get the absolute path of the current 709 This request can be used to get the absolute path of the current
579 working directory by passing it a path of . (a single dot). 710 working directory by passing it a path of . (a single dot).
580 711
581 aio_rename $srcpath, $dstpath, $callback->($status) 712 aio_rename $srcpath, $dstpath, $callback->($status)
582 Asynchronously rename the object at $srcpath to $dstpath, just as 713 Asynchronously rename the object at $srcpath to $dstpath, just as
583 rename(2) and call the callback with the result code. 714 rename(2) and call the callback with the result code.
715
716 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd.
584 719
585 aio_mkdir $pathname, $mode, $callback->($status) 720 aio_mkdir $pathname, $mode, $callback->($status)
586 Asynchronously mkdir (create) a directory and call the callback with 721 Asynchronously mkdir (create) a directory and call the callback with
587 the result code. $mode will be modified by the umask at the time the 722 the result code. $mode will be modified by the umask at the time the
588 request is executed, so do not change your umask. 723 request is executed, so do not change your umask.
589 724
590 aio_rmdir $pathname, $callback->($status) 725 aio_rmdir $pathname, $callback->($status)
591 Asynchronously rmdir (delete) a directory and call the callback with 726 Asynchronously rmdir (delete) a directory and call the callback with
592 the result code. 727 the result code.
728
729 On systems that support the AIO::WD working directory abstraction
730 natively, the case "[$wd, "."]" is specialcased - instead of
731 failing, "rmdir" is called on the absolute path of $wd.
593 732
594 aio_readdir $pathname, $callback->($entries) 733 aio_readdir $pathname, $callback->($entries)
595 Unlike the POSIX call of the same name, "aio_readdir" reads an 734 Unlike the POSIX call of the same name, "aio_readdir" reads an
596 entire directory (i.e. opendir + readdir + closedir). The entries 735 entire directory (i.e. opendir + readdir + closedir). The entries
597 will not be sorted, and will NOT include the "." and ".." entries. 736 will not be sorted, and will NOT include the "." and ".." entries.
751 Delete a directory tree starting (and including) $path, return the 890 Delete a directory tree starting (and including) $path, return the
752 status of the final "rmdir" only. This is a composite request that 891 status of the final "rmdir" only. This is a composite request that
753 uses "aio_scandir" to recurse into and rmdir directories, and unlink 892 uses "aio_scandir" to recurse into and rmdir directories, and unlink
754 everything else. 893 everything else.
755 894
895 aio_fcntl $fh, $cmd, $arg, $callback->($status)
896 aio_ioctl $fh, $request, $buf, $callback->($status)
897 These work just like the "fcntl" and "ioctl" built-in functions,
898 except they execute asynchronously and pass the return value to the
899 callback.
900
901 Both calls can be used for a lot of things, some of which make more
902 sense to run asynchronously in their own thread, while some others
903 make less sense. For example, calls that block waiting for external
904 events, such as locking, will also lock down an I/O thread while it
905 is waiting, which can deadlock the whole I/O system. At the same
906 time, there might be no alternative to using a thread to wait.
907
908 So in general, you should only use these calls for things that do
909 (filesystem) I/O, not for things that wait for other events
910 (network, other processes), although if you are careful and know
911 what you are doing, you still can.
912
756 aio_sync $callback->($status) 913 aio_sync $callback->($status)
757 Asynchronously call sync and call the callback when finished. 914 Asynchronously call sync and call the callback when finished.
758 915
759 aio_fsync $fh, $callback->($status) 916 aio_fsync $fh, $callback->($status)
760 Asynchronously call fsync on the given filehandle and call the 917 Asynchronously call fsync on the given filehandle and call the
820 977
821 It touches (reads or writes) all memory pages in the specified range 978 It touches (reads or writes) all memory pages in the specified range
822 inside the scalar. All caveats and parameters are the same as for 979 inside the scalar. All caveats and parameters are the same as for
823 "aio_msync", above, except for flags, which must be either 0 (which 980 "aio_msync", above, except for flags, which must be either 0 (which
824 reads all pages and ensures they are instantiated) or 981 reads all pages and ensures they are instantiated) or
825 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 982 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
826 and writing an octet from it, which dirties the page). 983 and writing an octet from it, which dirties the page).
827 984
828 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 985 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
829 This is a rather advanced IO::AIO call, which works best on 986 This is a rather advanced IO::AIO call, which works best on
830 mmap(2)ed scalars. 987 mmap(2)ed scalars.
862 1019
863 Example: asynchronously lock all current and future pages into 1020 Example: asynchronously lock all current and future pages into
864 memory. 1021 memory.
865 1022
866 aio_mlockall IO::AIO::MCL_FUTURE; 1023 aio_mlockall IO::AIO::MCL_FUTURE;
1024
1025 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1026 Queries the extents of the given file (by calling the Linux "FIEMAP"
1027 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1028 details). If the ioctl is not available on your OS, then this
1029 request will fail with "ENOSYS".
1030
1031 $start is the starting offset to query extents for, $length is the
1032 size of the range to query - if it is "undef", then the whole file
1033 will be queried.
1034
1035 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1036 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1037 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1038 query the data portion.
1039
1040 $count is the maximum number of extent records to return. If it is
1041 "undef", then IO::AIO queries all extents of the range. As a very
1042 special case, if it is 0, then the callback receives the number of
1043 extents instead of the extents themselves (which is unreliable, see
1044 below).
1045
1046 If an error occurs, the callback receives no arguments. The special
1047 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1048
1049 Otherwise, the callback receives an array reference with extent
1050 structures. Each extent structure is an array reference itself, with
1051 the following members:
1052
1053 [$logical, $physical, $length, $flags]
1054
1055 Flags is any combination of the following flag values (typically
1056 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1057
1058 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1059 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1060 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1061 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1062 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1063 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1064 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1065 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1066
1067 At the time of this writing (Linux 3.2), this requets is unreliable
1068 unless $count is "undef", as the kernel has all sorts of bugs
1069 preventing it to return all extents of a range for files with large
1070 number of extents. The code works around all these issues if $count
1071 is undef.
867 1072
868 aio_group $callback->(...) 1073 aio_group $callback->(...)
869 This is a very special aio request: Instead of doing something, it 1074 This is a very special aio request: Instead of doing something, it
870 is a container for other aio requests, which is useful if you want 1075 is a container for other aio requests, which is useful if you want
871 to bundle many requests into a single, composite, request with a 1076 to bundle many requests into a single, composite, request with a
951 aio_stat [$etcdir, "passwd"], sub { 1156 aio_stat [$etcdir, "passwd"], sub {
952 # yay 1157 # yay
953 }; 1158 };
954 }; 1159 };
955 1160
956 That "aio_wd" is a request and not a normal function shows that creating 1161 The fact that "aio_wd" is a request and not a normal function shows that
957 an IO::AIO::WD object is itself a potentially blocking operation, which 1162 creating an IO::AIO::WD object is itself a potentially blocking
958 is why it is done asynchronously. 1163 operation, which is why it is done asynchronously.
959 1164
960 To stat the directory obtained with "aio_wd" above, one could write 1165 To stat the directory obtained with "aio_wd" above, one could write
961 either of the following three request calls: 1166 either of the following three request calls:
962 1167
963 aio_lstat "/etc" , sub { ... # pathname as normal string 1168 aio_lstat "/etc" , sub { ... # pathname as normal string
983 will still point to the original directory. Most functions accepting a 1188 will still point to the original directory. Most functions accepting a
984 pathname will use the directory fd on newer systems, and the string on 1189 pathname will use the directory fd on newer systems, and the string on
985 older systems. Some functions (such as realpath) will always rely on the 1190 older systems. Some functions (such as realpath) will always rely on the
986 string form of the pathname. 1191 string form of the pathname.
987 1192
988 So this fucntionality is mainly useful to get some protection against 1193 So this functionality is mainly useful to get some protection against
989 "chdir", to easily get an absolute path out of a relative path for 1194 "chdir", to easily get an absolute path out of a relative path for
990 future reference, and to speed up doing many operations in the same 1195 future reference, and to speed up doing many operations in the same
991 directory (e.g. when stat'ing all files in a directory). 1196 directory (e.g. when stat'ing all files in a directory).
992 1197
993 The following functions implement this working directory abstraction: 1198 The following functions implement this working directory abstraction:
1003 Since passing "undef" as working directory component of a pathname 1208 Since passing "undef" as working directory component of a pathname
1004 fails the request with "ENOENT", there is often no need for error 1209 fails the request with "ENOENT", there is often no need for error
1005 checking in the "aio_wd" callback, as future requests using the 1210 checking in the "aio_wd" callback, as future requests using the
1006 value will fail in the expected way. 1211 value will fail in the expected way.
1007 1212
1008 If this call isn't available because your OS lacks it or it couldn't
1009 be detected, it will be emulated by calling "fsync" instead.
1010
1011 IO::AIO::CWD 1213 IO::AIO::CWD
1012 This is a compiletime constant (object) that represents the process 1214 This is a compiletime constant (object) that represents the process
1013 current working directory. 1215 current working directory.
1014 1216
1015 Specifying this object as working directory object for a pathname is 1217 Specifying this object as working directory object for a pathname is
1016 as if the pathname would be specified directly, without a directory 1218 as if the pathname would be specified directly, without a directory
1017 object, e.g., these calls are functionally identical: 1219 object. For example, these calls are functionally identical:
1018 1220
1019 aio_stat "somefile", sub { ... }; 1221 aio_stat "somefile", sub { ... };
1020 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1222 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1223
1224 To recover the path associated with an IO::AIO::WD object, you can use
1225 "aio_realpath":
1226
1227 aio_realpath $wd, sub {
1228 warn "path is $_[0]\n";
1229 };
1230
1231 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1232 sometimes, fall back to using an absolue path.
1021 1233
1022 IO::AIO::REQ CLASS 1234 IO::AIO::REQ CLASS
1023 All non-aggregate "aio_*" functions return an object of this class when 1235 All non-aggregate "aio_*" functions return an object of this class when
1024 called in non-void context. 1236 called in non-void context.
1025 1237
1177 results. 1389 results.
1178 1390
1179 See "poll_cb" for an example. 1391 See "poll_cb" for an example.
1180 1392
1181 IO::AIO::poll_cb 1393 IO::AIO::poll_cb
1182 Process some outstanding events on the result pipe. You have to call 1394 Process some requests that have reached the result phase (i.e. they
1395 have been executed but the results are not yet reported). You have
1396 to call this "regularly" to finish outstanding requests.
1397
1183 this regularly. Returns 0 if all events could be processed (or there 1398 Returns 0 if all events could be processed (or there were no events
1184 were no events to process), or -1 if it returned earlier for 1399 to process), or -1 if it returned earlier for whatever reason.
1185 whatever reason. Returns immediately when no events are outstanding. 1400 Returns immediately when no events are outstanding. The amount of
1186 The amount of events processed depends on the settings of 1401 events processed depends on the settings of "IO::AIO::max_poll_req",
1187 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1402 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1188 1403
1189 If not all requests were processed for whatever reason, the 1404 If not all requests were processed for whatever reason, the poll
1190 filehandle will still be ready when "poll_cb" returns, so normally 1405 file descriptor will still be ready when "poll_cb" returns, so
1191 you don't have to do anything special to have it called later. 1406 normally you don't have to do anything special to have it called
1407 later.
1192 1408
1193 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1409 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1194 becomes ready, it can be beneficial to call this function from loops 1410 becomes ready, it can be beneficial to call this function from loops
1195 which submit a lot of requests, to make sure the results get 1411 which submit a lot of requests, to make sure the results get
1196 processed when they become available and not just when the loop is 1412 processed when they become available and not just when the loop is
1204 Event->io (fd => IO::AIO::poll_fileno, 1420 Event->io (fd => IO::AIO::poll_fileno,
1205 poll => 'r', async => 1, 1421 poll => 'r', async => 1,
1206 cb => \&IO::AIO::poll_cb); 1422 cb => \&IO::AIO::poll_cb);
1207 1423
1208 IO::AIO::poll_wait 1424 IO::AIO::poll_wait
1209 If there are any outstanding requests and none of them in the result 1425 Wait until either at least one request is in the result phase or no
1210 phase, wait till the result filehandle becomes ready for reading 1426 requests are outstanding anymore.
1211 (simply does a "select" on the filehandle. This is useful if you 1427
1212 want to synchronously wait for some requests to finish). 1428 This is useful if you want to synchronously wait for some requests
1429 to become ready, without actually handling them.
1213 1430
1214 See "nreqs" for an example. 1431 See "nreqs" for an example.
1215 1432
1216 IO::AIO::poll 1433 IO::AIO::poll
1217 Waits until some requests have been handled. 1434 Waits until some requests have been handled.
1329 1546
1330 This is a very bad function to use in interactive programs because 1547 This is a very bad function to use in interactive programs because
1331 it blocks, and a bad way to reduce concurrency because it is 1548 it blocks, and a bad way to reduce concurrency because it is
1332 inexact: Better use an "aio_group" together with a feed callback. 1549 inexact: Better use an "aio_group" together with a feed callback.
1333 1550
1334 It's main use is in scripts without an event loop - when you want to 1551 Its main use is in scripts without an event loop - when you want to
1335 stat a lot of files, you can write somehting like this: 1552 stat a lot of files, you can write somehting like this:
1336 1553
1337 IO::AIO::max_outstanding 32; 1554 IO::AIO::max_outstanding 32;
1338 1555
1339 for my $path (...) { 1556 for my $path (...) {
1370 IO::AIO::npending 1587 IO::AIO::npending
1371 Returns the number of requests currently in the pending state 1588 Returns the number of requests currently in the pending state
1372 (executed, but not yet processed by poll_cb). 1589 (executed, but not yet processed by poll_cb).
1373 1590
1374 MISCELLANEOUS FUNCTIONS 1591 MISCELLANEOUS FUNCTIONS
1375 IO::AIO implements some functions that might be useful, but are not 1592 IO::AIO implements some functions that are useful when you want to use
1376 asynchronous. 1593 some "Advanced I/O" function not available to in Perl, without going the
1594 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1595 counterpart.
1377 1596
1378 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1379 Calls the "eio_sendfile_sync" function, which is like 1598 Calls the "eio_sendfile_sync" function, which is like
1380 "aio_sendfile", but is blocking (this makes most sense if you know 1599 "aio_sendfile", but is blocking (this makes most sense if you know
1381 the input data is likely cached already and the output filehandle is 1600 the input data is likely cached already and the output filehandle is
1412 On systems that do not implement "mprotect", this function returns 1631 On systems that do not implement "mprotect", this function returns
1413 ENOSYS, otherwise the return value of "mprotect". 1632 ENOSYS, otherwise the return value of "mprotect".
1414 1633
1415 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1416 Memory-maps a file (or anonymous memory range) and attaches it to 1635 Memory-maps a file (or anonymous memory range) and attaches it to
1417 the given $scalar, which will act like a string scalar. 1636 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise.
1418 1638
1419 The only operations allowed on the scalar are "substr"/"vec" that 1639 The only operations allowed on the scalar are "substr"/"vec" that
1420 don't change the string length, and most read-only operations such 1640 don't change the string length, and most read-only operations such
1421 as copying it or searching it with regexes and so on. 1641 as copying it or searching it with regexes and so on.
1422 1642
1436 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1656 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1437 "IO::AIO::PROT_WRITE", 1657 "IO::AIO::PROT_WRITE",
1438 1658
1439 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1659 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1440 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1660 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1441 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1661 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1442 (which is set to "MAP_ANON" if your system only provides this 1662 "MAP_ANON" if your system only provides this constant),
1663 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1443 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1664 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1665 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1444 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1666 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1445 "IO::AIO::MAP_NONBLOCK" 1667 "IO::AIO::MAP_STACK".
1446 1668
1447 If $fh is "undef", then a file descriptor of -1 is passed. 1669 If $fh is "undef", then a file descriptor of -1 is passed.
1448 1670
1449 $offset is the offset from the start of the file - it generally must 1671 $offset is the offset from the start of the file - it generally must
1450 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1672 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1472 IO::AIO::munlockall 1694 IO::AIO::munlockall
1473 Calls the "munlockall" function. 1695 Calls the "munlockall" function.
1474 1696
1475 On systems that do not implement "munlockall", this function returns 1697 On systems that do not implement "munlockall", this function returns
1476 ENOSYS, otherwise the return value of "munlockall". 1698 ENOSYS, otherwise the return value of "munlockall".
1699
1700 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1701 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1702 $w_off are "undef", then "NULL" is passed for these, otherwise they
1703 should be the file offset.
1704
1705 $r_fh and $w_fh should not refer to the same file, as splice might
1706 silently corrupt the data in this case.
1707
1708 The following symbol flag values are available:
1709 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1710 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1711
1712 See the splice(2) manpage for details.
1713
1714 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1715 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1716 description for "IO::AIO::splice" above for details.
1717
1718 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1719 Attempts to query or change the pipe buffer size. Obviously works
1720 only on pipes, and currently works only on GNU/Linux systems, and
1721 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1722 influence pipe buffer size on other systems, drop me a note.
1723
1724 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1725 This is a direct interface to the Linux pipe2(2) system call. If
1726 $flags is missing or 0, then this should be the same as a call to
1727 perl's built-in "pipe" function and create a new pipe, and works on
1728 systems that lack the pipe2 syscall. On win32, this case invokes
1729 "_pipe (..., 4096, O_BINARY)".
1730
1731 If $flags is non-zero, it tries to invoke the pipe2 system call with
1732 the given flags (Linux 2.6.27, glibc 2.9).
1733
1734 On success, the read and write file handles are returned.
1735
1736 On error, nothing will be returned. If the pipe2 syscall is missing
1737 and $flags is non-zero, fails with "ENOSYS".
1738
1739 Please refer to pipe2(2) for more info on the $flags, but at the
1740 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1741 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1742 supported.
1477 1743
1478EVENT LOOP INTEGRATION 1744EVENT LOOP INTEGRATION
1479 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1480 automatically into many event loops: 1746 automatically into many event loops:
1481 1747

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