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Revision 1.231 by root, Fri Jul 27 19:03:18 2012 UTC vs.
Revision 1.273 by root, Fri Jun 23 22:33:06 2017 UTC

1=head1 NAME 1=head1 NAME
2 2
3IO::AIO - Asynchronous Input/Output 3IO::AIO - Asynchronous/Advanced Input/Output
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
58not well-supported or restricted (GNU/Linux doesn't allow them on normal 58not well-supported or restricted (GNU/Linux doesn't allow them on normal
59files currently, for example), and they would only support aio_read and 59files currently, for example), and they would only support aio_read and
60aio_write, so the remaining functionality would have to be implemented 60aio_write, so the remaining functionality would have to be implemented
61using threads anyway. 61using threads anyway.
62 62
63In addition to asynchronous I/O, this module also exports some rather
64arcane interfaces, such as C<madvise> or linux's C<splice> system call,
65which is why the C<A> in C<AIO> can also mean I<advanced>.
66
63Although the module will work in the presence of other (Perl-) threads, 67Although the module will work in the presence of other (Perl-) threads,
64it is currently not reentrant in any way, so use appropriate locking 68it is currently not reentrant in any way, so use appropriate locking
65yourself, always call C<poll_cb> from within the same thread, or never 69yourself, always call C<poll_cb> from within the same thread, or never
66call C<poll_cb> (or other C<aio_> functions) recursively. 70call C<poll_cb> (or other C<aio_> functions) recursively.
67 71
68=head2 EXAMPLE 72=head2 EXAMPLE
69 73
70This is a simple example that uses the EV module and loads 74This is a simple example that uses the EV module and loads
71F</etc/passwd> asynchronously: 75F</etc/passwd> asynchronously:
72 76
73 use Fcntl;
74 use EV; 77 use EV;
75 use IO::AIO; 78 use IO::AIO;
76 79
77 # register the IO::AIO callback with EV 80 # register the IO::AIO callback with EV
78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 81 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95 98
96 # file contents now in $contents 99 # file contents now in $contents
97 print $contents; 100 print $contents;
98 101
99 # exit event loop and program 102 # exit event loop and program
100 EV::unloop; 103 EV::break;
101 }; 104 };
102 }; 105 };
103 106
104 # possibly queue up other requests, or open GUI windows, 107 # possibly queue up other requests, or open GUI windows,
105 # check for sockets etc. etc. 108 # check for sockets etc. etc.
106 109
107 # process events as long as there are some: 110 # process events as long as there are some:
108 EV::loop; 111 EV::run;
109 112
110=head1 REQUEST ANATOMY AND LIFETIME 113=head1 REQUEST ANATOMY AND LIFETIME
111 114
112Every C<aio_*> function creates a request. which is a C data structure not 115Every C<aio_*> function creates a request. which is a C data structure not
113directly visible to Perl. 116directly visible to Perl.
168use common::sense; 171use common::sense;
169 172
170use base 'Exporter'; 173use base 'Exporter';
171 174
172BEGIN { 175BEGIN {
173 our $VERSION = '4.15'; 176 our $VERSION = 4.35;
174 177
175 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close 178 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 179 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync 180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate 181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179 aio_pathsync aio_readahead aio_fiemap 182 aio_pathsync aio_readahead aio_fiemap aio_allocate
180 aio_rename aio_link aio_move aio_copy aio_group 183 aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 184 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182 aio_chmod aio_utime aio_truncate 185 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall 186 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs 187 aio_statvfs
185 aio_wd); 188 aio_wd);
228 aio_unlink $pathname, $callback->($status) 231 aio_unlink $pathname, $callback->($status)
229 aio_mknod $pathname, $mode, $dev, $callback->($status) 232 aio_mknod $pathname, $mode, $dev, $callback->($status)
230 aio_link $srcpath, $dstpath, $callback->($status) 233 aio_link $srcpath, $dstpath, $callback->($status)
231 aio_symlink $srcpath, $dstpath, $callback->($status) 234 aio_symlink $srcpath, $dstpath, $callback->($status)
232 aio_readlink $pathname, $callback->($link) 235 aio_readlink $pathname, $callback->($link)
233 aio_realpath $pathname, $callback->($link) 236 aio_realpath $pathname, $callback->($path)
234 aio_rename $srcpath, $dstpath, $callback->($status) 237 aio_rename $srcpath, $dstpath, $callback->($status)
238 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
235 aio_mkdir $pathname, $mode, $callback->($status) 239 aio_mkdir $pathname, $mode, $callback->($status)
236 aio_rmdir $pathname, $callback->($status) 240 aio_rmdir $pathname, $callback->($status)
237 aio_readdir $pathname, $callback->($entries) 241 aio_readdir $pathname, $callback->($entries)
238 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 242 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
239 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 243 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 245 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242 aio_load $pathname, $data, $callback->($status) 246 aio_load $pathname, $data, $callback->($status)
243 aio_copy $srcpath, $dstpath, $callback->($status) 247 aio_copy $srcpath, $dstpath, $callback->($status)
244 aio_move $srcpath, $dstpath, $callback->($status) 248 aio_move $srcpath, $dstpath, $callback->($status)
245 aio_rmtree $pathname, $callback->($status) 249 aio_rmtree $pathname, $callback->($status)
250 aio_fcntl $fh, $cmd, $arg, $callback->($status)
251 aio_ioctl $fh, $request, $buf, $callback->($status)
246 aio_sync $callback->($status) 252 aio_sync $callback->($status)
247 aio_syncfs $fh, $callback->($status) 253 aio_syncfs $fh, $callback->($status)
248 aio_fsync $fh, $callback->($status) 254 aio_fsync $fh, $callback->($status)
249 aio_fdatasync $fh, $callback->($status) 255 aio_fdatasync $fh, $callback->($status)
250 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 256 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
251 aio_pathsync $pathname, $callback->($status) 257 aio_pathsync $pathname, $callback->($status)
252 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 258 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
253 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 259 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
254 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 260 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
255 aio_mlockall $flags, $callback->($status) 261 aio_mlockall $flags, $callback->($status)
256 aio_group $callback->(...) 262 aio_group $callback->(...)
257 aio_nop $callback->() 263 aio_nop $callback->()
362 368
363 369
364=item aio_open $pathname, $flags, $mode, $callback->($fh) 370=item aio_open $pathname, $flags, $mode, $callback->($fh)
365 371
366Asynchronously open or create a file and call the callback with a newly 372Asynchronously open or create a file and call the callback with a newly
367created filehandle for the file. 373created filehandle for the file (or C<undef> in case of an error).
368 374
369The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 375The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
370for an explanation. 376for an explanation.
371 377
372The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 378The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
395following POSIX and non-POSIX constants are available (missing ones on 401following POSIX and non-POSIX constants are available (missing ones on
396your system are, as usual, C<0>): 402your system are, as usual, C<0>):
397 403
398C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 404C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
399C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 405C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
400C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 406C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
401 407
402 408
403=item aio_close $fh, $callback->($status) 409=item aio_close $fh, $callback->($status)
404 410
405Asynchronously close a file and call the callback with the result 411Asynchronously close a file and call the callback with the result
440=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 446=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
441 447
442=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 448=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
443 449
444Reads or writes C<$length> bytes from or to the specified C<$fh> and 450Reads or writes C<$length> bytes from or to the specified C<$fh> and
445C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 451C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
446and calls the callback without the actual number of bytes read (or -1 on 452calls the callback with the actual number of bytes transferred (or -1 on
447error, just like the syscall). 453error, just like the syscall).
448 454
449C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to 455C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
450offset plus the actual number of bytes read. 456offset plus the actual number of bytes read.
451 457
509As native sendfile syscalls (as practically any non-POSIX interface hacked 515As native sendfile syscalls (as practically any non-POSIX interface hacked
510together in a hurry to improve benchmark numbers) tend to be rather buggy 516together in a hurry to improve benchmark numbers) tend to be rather buggy
511on many systems, this implementation tries to work around some known bugs 517on many systems, this implementation tries to work around some known bugs
512in Linux and FreeBSD kernels (probably others, too), but that might fail, 518in Linux and FreeBSD kernels (probably others, too), but that might fail,
513so you really really should check the return value of C<aio_sendfile> - 519so you really really should check the return value of C<aio_sendfile> -
514fewre bytes than expected might have been transferred. 520fewer bytes than expected might have been transferred.
515 521
516 522
517=item aio_readahead $fh,$offset,$length, $callback->($retval) 523=item aio_readahead $fh,$offset,$length, $callback->($retval)
518 524
519C<aio_readahead> populates the page cache with data from a file so that 525C<aio_readahead> populates the page cache with data from a file so that
523whole pages, so that offset is effectively rounded down to a page boundary 529whole pages, so that offset is effectively rounded down to a page boundary
524and bytes are read up to the next page boundary greater than or equal to 530and bytes are read up to the next page boundary greater than or equal to
525(off-set+length). C<aio_readahead> does not read beyond the end of the 531(off-set+length). C<aio_readahead> does not read beyond the end of the
526file. The current file offset of the file is left unchanged. 532file. The current file offset of the file is left unchanged.
527 533
528If that syscall doesn't exist (likely if your OS isn't Linux) it will be 534If that syscall doesn't exist (likely if your kernel isn't Linux) it will
529emulated by simply reading the data, which would have a similar effect. 535be emulated by simply reading the data, which would have a similar effect.
530 536
531 537
532=item aio_stat $fh_or_path, $callback->($status) 538=item aio_stat $fh_or_path, $callback->($status)
533 539
534=item aio_lstat $fh, $callback->($status) 540=item aio_lstat $fh, $callback->($status)
603 namemax => 255, 609 namemax => 255,
604 frsize => 1024, 610 frsize => 1024,
605 fsid => 1810 611 fsid => 1810
606 } 612 }
607 613
614Here is a (likely partial - send me updates!) list of fsid values used by
615Linux - it is safe to hardcode these when C<$^O> is C<linux>:
616
617 0x0000adf5 adfs
618 0x0000adff affs
619 0x5346414f afs
620 0x09041934 anon-inode filesystem
621 0x00000187 autofs
622 0x42465331 befs
623 0x1badface bfs
624 0x42494e4d binfmt_misc
625 0x9123683e btrfs
626 0x0027e0eb cgroupfs
627 0xff534d42 cifs
628 0x73757245 coda
629 0x012ff7b7 coh
630 0x28cd3d45 cramfs
631 0x453dcd28 cramfs-wend (wrong endianness)
632 0x64626720 debugfs
633 0x00001373 devfs
634 0x00001cd1 devpts
635 0x0000f15f ecryptfs
636 0x00414a53 efs
637 0x0000137d ext
638 0x0000ef53 ext2/ext3/ext4
639 0x0000ef51 ext2
640 0xf2f52010 f2fs
641 0x00004006 fat
642 0x65735546 fuseblk
643 0x65735543 fusectl
644 0x0bad1dea futexfs
645 0x01161970 gfs2
646 0x47504653 gpfs
647 0x00004244 hfs
648 0xf995e849 hpfs
649 0x00c0ffee hostfs
650 0x958458f6 hugetlbfs
651 0x2bad1dea inotifyfs
652 0x00009660 isofs
653 0x000072b6 jffs2
654 0x3153464a jfs
655 0x6b414653 k-afs
656 0x0bd00bd0 lustre
657 0x0000137f minix
658 0x0000138f minix 30 char names
659 0x00002468 minix v2
660 0x00002478 minix v2 30 char names
661 0x00004d5a minix v3
662 0x19800202 mqueue
663 0x00004d44 msdos
664 0x0000564c novell
665 0x00006969 nfs
666 0x6e667364 nfsd
667 0x00003434 nilfs
668 0x5346544e ntfs
669 0x00009fa1 openprom
670 0x7461636F ocfs2
671 0x00009fa0 proc
672 0x6165676c pstorefs
673 0x0000002f qnx4
674 0x68191122 qnx6
675 0x858458f6 ramfs
676 0x52654973 reiserfs
677 0x00007275 romfs
678 0x67596969 rpc_pipefs
679 0x73636673 securityfs
680 0xf97cff8c selinux
681 0x0000517b smb
682 0x534f434b sockfs
683 0x73717368 squashfs
684 0x62656572 sysfs
685 0x012ff7b6 sysv2
686 0x012ff7b5 sysv4
687 0x01021994 tmpfs
688 0x15013346 udf
689 0x00011954 ufs
690 0x54190100 ufs byteswapped
691 0x00009fa2 usbdevfs
692 0x01021997 v9fs
693 0xa501fcf5 vxfs
694 0xabba1974 xenfs
695 0x012ff7b4 xenix
696 0x58465342 xfs
697 0x012fd16d xia
608 698
609=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 699=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
610 700
611Works like perl's C<utime> function (including the special case of $atime 701Works like perl's C<utime> function (including the special case of $atime
612and $mtime being undef). Fractional times are supported if the underlying 702and $mtime being undef). Fractional times are supported if the underlying
642Works like truncate(2) or ftruncate(2). 732Works like truncate(2) or ftruncate(2).
643 733
644 734
645=item aio_allocate $fh, $mode, $offset, $len, $callback->($status) 735=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
646 736
647Allocates or freed disk space according to the C<$mode> argument. See the 737Allocates or frees disk space according to the C<$mode> argument. See the
648linux C<fallocate> docuemntation for details. 738linux C<fallocate> documentation for details.
649 739
650C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> 740C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
651to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | 741space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
652IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range. 742to deallocate a file range.
743
744IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
745(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
746C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
747to unshare shared blocks (see your L<fallocate(2)> manpage).
653 748
654The file system block size used by C<fallocate> is presumably the 749The file system block size used by C<fallocate> is presumably the
655C<f_bsize> returned by C<statvfs>. 750C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
751can dictate other limitations.
656 752
657If C<fallocate> isn't available or cannot be emulated (currently no 753If C<fallocate> isn't available or cannot be emulated (currently no
658emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>. 754emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
659 755
660 756
702 798
703 799
704=item aio_realpath $pathname, $callback->($path) 800=item aio_realpath $pathname, $callback->($path)
705 801
706Asynchronously make the path absolute and resolve any symlinks in 802Asynchronously make the path absolute and resolve any symlinks in
707C<$path>. The resulting path only consists of directories (Same as 803C<$path>. The resulting path only consists of directories (same as
708L<Cwd::realpath>). 804L<Cwd::realpath>).
709 805
710This request can be used to get the absolute path of the current working 806This request can be used to get the absolute path of the current working
711directory by passing it a path of F<.> (a single dot). 807directory by passing it a path of F<.> (a single dot).
712 808
713 809
714=item aio_rename $srcpath, $dstpath, $callback->($status) 810=item aio_rename $srcpath, $dstpath, $callback->($status)
715 811
716Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 812Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
717rename(2) and call the callback with the result code. 813rename(2) and call the callback with the result code.
814
815On systems that support the AIO::WD working directory abstraction
816natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
817of failing, C<rename> is called on the absolute path of C<$wd>.
818
819
820=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
821
822Basically a version of C<aio_rename> with an additional C<$flags>
823argument. Calling this with C<$flags=0> is the same as calling
824C<aio_rename>.
825
826Non-zero flags are currently only supported on GNU/Linux systems that
827support renameat2. Other systems fail with C<ENOSYS> in this case.
828
829The following constants are available (missing ones are, as usual C<0>),
830see renameat2(2) for details:
831
832C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
833and C<IO::AIO::RENAME_WHITEOUT>.
718 834
719 835
720=item aio_mkdir $pathname, $mode, $callback->($status) 836=item aio_mkdir $pathname, $mode, $callback->($status)
721 837
722Asynchronously mkdir (create) a directory and call the callback with 838Asynchronously mkdir (create) a directory and call the callback with
726 842
727=item aio_rmdir $pathname, $callback->($status) 843=item aio_rmdir $pathname, $callback->($status)
728 844
729Asynchronously rmdir (delete) a directory and call the callback with the 845Asynchronously rmdir (delete) a directory and call the callback with the
730result code. 846result code.
847
848On systems that support the AIO::WD working directory abstraction
849natively, the case C<[$wd, "."]> is specialcased - instead of failing,
850C<rmdir> is called on the absolute path of C<$wd>.
731 851
732 852
733=item aio_readdir $pathname, $callback->($entries) 853=item aio_readdir $pathname, $callback->($entries)
734 854
735Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 855Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
1100} 1220}
1101 1221
1102=item aio_rmtree $pathname, $callback->($status) 1222=item aio_rmtree $pathname, $callback->($status)
1103 1223
1104Delete a directory tree starting (and including) C<$path>, return the 1224Delete a directory tree starting (and including) C<$path>, return the
1105status of the final C<rmdir> only. This is a composite request that 1225status of the final C<rmdir> only. This is a composite request that
1106uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1226uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1107everything else. 1227everything else.
1108 1228
1109=cut 1229=cut
1110 1230
1131 add $grp $dirgrp; 1251 add $grp $dirgrp;
1132 }; 1252 };
1133 1253
1134 $grp 1254 $grp
1135} 1255}
1256
1257=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1258
1259=item aio_ioctl $fh, $request, $buf, $callback->($status)
1260
1261These work just like the C<fcntl> and C<ioctl> built-in functions, except
1262they execute asynchronously and pass the return value to the callback.
1263
1264Both calls can be used for a lot of things, some of which make more sense
1265to run asynchronously in their own thread, while some others make less
1266sense. For example, calls that block waiting for external events, such
1267as locking, will also lock down an I/O thread while it is waiting, which
1268can deadlock the whole I/O system. At the same time, there might be no
1269alternative to using a thread to wait.
1270
1271So in general, you should only use these calls for things that do
1272(filesystem) I/O, not for things that wait for other events (network,
1273other processes), although if you are careful and know what you are doing,
1274you still can.
1275
1276The following constants are available (missing ones are, as usual C<0>):
1277
1278C<F_DUPFD_CLOEXEC>,
1279
1280C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
1281
1282C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1283
1284C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1285C<FS_IOC_FIEMAP>.
1286
1287C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1288C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1289
1290C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1291C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1292C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1293C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1294C<FS_FL_USER_MODIFIABLE>.
1295
1296C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1297C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1298C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1299C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1136 1300
1137=item aio_sync $callback->($status) 1301=item aio_sync $callback->($status)
1138 1302
1139Asynchronously call sync and call the callback when finished. 1303Asynchronously call sync and call the callback when finished.
1140 1304
1209 }; 1373 };
1210 1374
1211 $grp 1375 $grp
1212} 1376}
1213 1377
1214=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1378=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1215 1379
1216This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1380This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1217scalars (see the C<IO::AIO::mmap> function, although it also works on data 1381scalars (see the C<IO::AIO::mmap> function, although it also works on data
1218scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1382scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1219scalar must only be modified in-place while an aio operation is pending on 1383scalar must only be modified in-place while an aio operation is pending on
1221 1385
1222It calls the C<msync> function of your OS, if available, with the memory 1386It calls the C<msync> function of your OS, if available, with the memory
1223area starting at C<$offset> in the string and ending C<$length> bytes 1387area starting at C<$offset> in the string and ending C<$length> bytes
1224later. If C<$length> is negative, counts from the end, and if C<$length> 1388later. If C<$length> is negative, counts from the end, and if C<$length>
1225is C<undef>, then it goes till the end of the string. The flags can be 1389is C<undef>, then it goes till the end of the string. The flags can be
1226a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1390either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1227C<IO::AIO::MS_SYNC>. 1391C<IO::AIO::MS_INVALIDATE>.
1228 1392
1229=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1393=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1230 1394
1231This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1395This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1232scalars. 1396scalars.
1233 1397
1234It touches (reads or writes) all memory pages in the specified 1398It touches (reads or writes) all memory pages in the specified
1235range inside the scalar. All caveats and parameters are the same 1399range inside the scalar. All caveats and parameters are the same
1236as for C<aio_msync>, above, except for flags, which must be either 1400as for C<aio_msync>, above, except for flags, which must be either
1237C<0> (which reads all pages and ensures they are instantiated) or 1401C<0> (which reads all pages and ensures they are instantiated) or
1238C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1402C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1239writing an octet from it, which dirties the page). 1403writing an octet from it, which dirties the page).
1240 1404
1241=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1405=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1242 1406
1243This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1407This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1277 1441
1278 aio_mlockall IO::AIO::MCL_FUTURE; 1442 aio_mlockall IO::AIO::MCL_FUTURE;
1279 1443
1280=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) 1444=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1281 1445
1282Queries the extents of the given file (by calling the Linux FIEMAP ioctl, 1446Queries the extents of the given file (by calling the Linux C<FIEMAP>
1283see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the 1447ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1284C<ioctl> is not available on your OS, then this request will fail with 1448the ioctl is not available on your OS, then this request will fail with
1285C<ENOSYS>. 1449C<ENOSYS>.
1286 1450
1287C<$start> is the starting offset to query extents for, C<$length> is the 1451C<$start> is the starting offset to query extents for, C<$length> is the
1288size of the range to query - if it is C<undef>, then the whole file will 1452size of the range to query - if it is C<undef>, then the whole file will
1289be queried. 1453be queried.
1292C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also 1456C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1293exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query 1457exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1294the data portion. 1458the data portion.
1295 1459
1296C<$count> is the maximum number of extent records to return. If it is 1460C<$count> is the maximum number of extent records to return. If it is
1297C<undef>, then IO::AIO queries all extents of the file. As a very special 1461C<undef>, then IO::AIO queries all extents of the range. As a very special
1298case, if it is C<0>, then the callback receives the number of extents 1462case, if it is C<0>, then the callback receives the number of extents
1299instead of the extents themselves. 1463instead of the extents themselves (which is unreliable, see below).
1300 1464
1301If an error occurs, the callback receives no arguments. The special 1465If an error occurs, the callback receives no arguments. The special
1302C<errno> value C<IO::AIO::EBADR> is available to test for flag errors. 1466C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1303 1467
1304Otherwise, the callback receives an array reference with extent 1468Otherwise, the callback receives an array reference with extent
1315C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>, 1479C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1316C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>, 1480C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1317C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or 1481C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1318C<IO::AIO::FIEMAP_EXTENT_SHARED>. 1482C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1319 1483
1484At the time of this writing (Linux 3.2), this requets is unreliable unless
1485C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1486it to return all extents of a range for files with large number of
1487extents. The code works around all these issues if C<$count> is undef.
1488
1320=item aio_group $callback->(...) 1489=item aio_group $callback->(...)
1321 1490
1322This is a very special aio request: Instead of doing something, it is a 1491This is a very special aio request: Instead of doing something, it is a
1323container for other aio requests, which is useful if you want to bundle 1492container for other aio requests, which is useful if you want to bundle
1324many requests into a single, composite, request with a definite callback 1493many requests into a single, composite, request with a definite callback
1407 aio_stat [$etcdir, "passwd"], sub { 1576 aio_stat [$etcdir, "passwd"], sub {
1408 # yay 1577 # yay
1409 }; 1578 };
1410 }; 1579 };
1411 1580
1412That C<aio_wd> is a request and not a normal function shows that creating 1581The fact that C<aio_wd> is a request and not a normal function shows that
1413an IO::AIO::WD object is itself a potentially blocking operation, which is 1582creating an IO::AIO::WD object is itself a potentially blocking operation,
1414why it is done asynchronously. 1583which is why it is done asynchronously.
1415 1584
1416To stat the directory obtained with C<aio_wd> above, one could write 1585To stat the directory obtained with C<aio_wd> above, one could write
1417either of the following three request calls: 1586either of the following three request calls:
1418 1587
1419 aio_lstat "/etc" , sub { ... # pathname as normal string 1588 aio_lstat "/etc" , sub { ... # pathname as normal string
1439will still point to the original directory. Most functions accepting a 1608will still point to the original directory. Most functions accepting a
1440pathname will use the directory fd on newer systems, and the string on 1609pathname will use the directory fd on newer systems, and the string on
1441older systems. Some functions (such as realpath) will always rely on the 1610older systems. Some functions (such as realpath) will always rely on the
1442string form of the pathname. 1611string form of the pathname.
1443 1612
1444So this fucntionality is mainly useful to get some protection against 1613So this functionality is mainly useful to get some protection against
1445C<chdir>, to easily get an absolute path out of a relative path for future 1614C<chdir>, to easily get an absolute path out of a relative path for future
1446reference, and to speed up doing many operations in the same directory 1615reference, and to speed up doing many operations in the same directory
1447(e.g. when stat'ing all files in a directory). 1616(e.g. when stat'ing all files in a directory).
1448 1617
1449The following functions implement this working directory abstraction: 1618The following functions implement this working directory abstraction:
1462passing C<undef> as working directory component of a pathname fails the 1631passing C<undef> as working directory component of a pathname fails the
1463request with C<ENOENT>, there is often no need for error checking in the 1632request with C<ENOENT>, there is often no need for error checking in the
1464C<aio_wd> callback, as future requests using the value will fail in the 1633C<aio_wd> callback, as future requests using the value will fail in the
1465expected way. 1634expected way.
1466 1635
1467If this call isn't available because your OS lacks it or it couldn't be
1468detected, it will be emulated by calling C<fsync> instead.
1469
1470=item IO::AIO::CWD 1636=item IO::AIO::CWD
1471 1637
1472This is a compiletime constant (object) that represents the process 1638This is a compiletime constant (object) that represents the process
1473current working directory. 1639current working directory.
1474 1640
1475Specifying this object as working directory object for a pathname is as 1641Specifying this object as working directory object for a pathname is as if
1476if the pathname would be specified directly, without a directory object, 1642the pathname would be specified directly, without a directory object. For
1477e.g., these calls are functionally identical: 1643example, these calls are functionally identical:
1478 1644
1479 aio_stat "somefile", sub { ... }; 1645 aio_stat "somefile", sub { ... };
1480 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1646 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1481 1647
1482=back 1648=back
1483 1649
1650To recover the path associated with an IO::AIO::WD object, you can use
1651C<aio_realpath>:
1652
1653 aio_realpath $wd, sub {
1654 warn "path is $_[0]\n";
1655 };
1656
1657Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1658sometimes, fall back to using an absolue path.
1484 1659
1485=head2 IO::AIO::REQ CLASS 1660=head2 IO::AIO::REQ CLASS
1486 1661
1487All non-aggregate C<aio_*> functions return an object of this class when 1662All non-aggregate C<aio_*> functions return an object of this class when
1488called in non-void context. 1663called in non-void context.
1666 1841
1667See C<poll_cb> for an example. 1842See C<poll_cb> for an example.
1668 1843
1669=item IO::AIO::poll_cb 1844=item IO::AIO::poll_cb
1670 1845
1671Process some outstanding events on the result pipe. You have to call 1846Process some requests that have reached the result phase (i.e. they have
1847been executed but the results are not yet reported). You have to call
1848this "regularly" to finish outstanding requests.
1849
1672this regularly. Returns C<0> if all events could be processed (or there 1850Returns C<0> if all events could be processed (or there were no
1673were no events to process), or C<-1> if it returned earlier for whatever 1851events to process), or C<-1> if it returned earlier for whatever
1674reason. Returns immediately when no events are outstanding. The amount of 1852reason. Returns immediately when no events are outstanding. The amount
1675events processed depends on the settings of C<IO::AIO::max_poll_req> and 1853of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1676C<IO::AIO::max_poll_time>. 1854C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1677 1855
1678If not all requests were processed for whatever reason, the filehandle 1856If not all requests were processed for whatever reason, the poll file
1679will still be ready when C<poll_cb> returns, so normally you don't have to 1857descriptor will still be ready when C<poll_cb> returns, so normally you
1680do anything special to have it called later. 1858don't have to do anything special to have it called later.
1681 1859
1682Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1860Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1683ready, it can be beneficial to call this function from loops which submit 1861ready, it can be beneficial to call this function from loops which submit
1684a lot of requests, to make sure the results get processed when they become 1862a lot of requests, to make sure the results get processed when they become
1685available and not just when the loop is finished and the event loop takes 1863available and not just when the loop is finished and the event loop takes
1694 poll => 'r', async => 1, 1872 poll => 'r', async => 1,
1695 cb => \&IO::AIO::poll_cb); 1873 cb => \&IO::AIO::poll_cb);
1696 1874
1697=item IO::AIO::poll_wait 1875=item IO::AIO::poll_wait
1698 1876
1699If there are any outstanding requests and none of them in the result 1877Wait until either at least one request is in the result phase or no
1700phase, wait till the result filehandle becomes ready for reading (simply 1878requests are outstanding anymore.
1701does a C<select> on the filehandle. This is useful if you want to 1879
1702synchronously wait for some requests to finish). 1880This is useful if you want to synchronously wait for some requests to
1881become ready, without actually handling them.
1703 1882
1704See C<nreqs> for an example. 1883See C<nreqs> for an example.
1705 1884
1706=item IO::AIO::poll 1885=item IO::AIO::poll
1707 1886
1828 2007
1829This is a very bad function to use in interactive programs because it 2008This is a very bad function to use in interactive programs because it
1830blocks, and a bad way to reduce concurrency because it is inexact: Better 2009blocks, and a bad way to reduce concurrency because it is inexact: Better
1831use an C<aio_group> together with a feed callback. 2010use an C<aio_group> together with a feed callback.
1832 2011
1833It's main use is in scripts without an event loop - when you want to stat 2012Its main use is in scripts without an event loop - when you want to stat
1834a lot of files, you can write somehting like this: 2013a lot of files, you can write somehting like this:
1835 2014
1836 IO::AIO::max_outstanding 32; 2015 IO::AIO::max_outstanding 32;
1837 2016
1838 for my $path (...) { 2017 for my $path (...) {
1878 2057
1879=back 2058=back
1880 2059
1881=head3 MISCELLANEOUS FUNCTIONS 2060=head3 MISCELLANEOUS FUNCTIONS
1882 2061
1883IO::AIO implements some functions that might be useful, but are not 2062IO::AIO implements some functions that are useful when you want to use
1884asynchronous. 2063some "Advanced I/O" function not available to in Perl, without going the
2064"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2065counterpart.
1885 2066
1886=over 4 2067=over 4
1887 2068
1888=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2069=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1889 2070
1908=item IO::AIO::madvise $scalar, $offset, $len, $advice 2089=item IO::AIO::madvise $scalar, $offset, $len, $advice
1909 2090
1910Simply calls the C<posix_madvise> function (see its 2091Simply calls the C<posix_madvise> function (see its
1911manpage for details). The following advice constants are 2092manpage for details). The following advice constants are
1912available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2093available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1913C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2094C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
2095C<IO::AIO::MADV_DONTNEED>.
2096
2097If C<$offset> is negative, counts from the end. If C<$length> is negative,
2098the remaining length of the C<$scalar> is used. If possible, C<$length>
2099will be reduced to fit into the C<$scalar>.
1914 2100
1915On systems that do not implement C<posix_madvise>, this function returns 2101On systems that do not implement C<posix_madvise>, this function returns
1916ENOSYS, otherwise the return value of C<posix_madvise>. 2102ENOSYS, otherwise the return value of C<posix_madvise>.
1917 2103
1918=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2104=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1920Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2106Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1921$scalar (see its manpage for details). The following protect 2107$scalar (see its manpage for details). The following protect
1922constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2108constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1923C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2109C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1924 2110
2111If C<$offset> is negative, counts from the end. If C<$length> is negative,
2112the remaining length of the C<$scalar> is used. If possible, C<$length>
2113will be reduced to fit into the C<$scalar>.
2114
1925On systems that do not implement C<mprotect>, this function returns 2115On systems that do not implement C<mprotect>, this function returns
1926ENOSYS, otherwise the return value of C<mprotect>. 2116ENOSYS, otherwise the return value of C<mprotect>.
1927 2117
1928=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2118=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1929 2119
1930Memory-maps a file (or anonymous memory range) and attaches it to the 2120Memory-maps a file (or anonymous memory range) and attaches it to the
1931given C<$scalar>, which will act like a string scalar. Returns true on 2121given C<$scalar>, which will act like a string scalar. Returns true on
1932success, and false otherwise. 2122success, and false otherwise.
1933 2123
2124The scalar must exist, but its contents do not matter - this means you
2125cannot use a nonexistant array or hash element. When in doubt, C<undef>
2126the scalar first.
2127
1934The only operations allowed on the scalar are C<substr>/C<vec> that don't 2128The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1935change the string length, and most read-only operations such as copying it 2129which don't change the string length, and most read-only operations such
1936or searching it with regexes and so on. 2130as copying it or searching it with regexes and so on.
1937 2131
1938Anything else is unsafe and will, at best, result in memory leaks. 2132Anything else is unsafe and will, at best, result in memory leaks.
1939 2133
1940The memory map associated with the C<$scalar> is automatically removed 2134The memory map associated with the C<$scalar> is automatically removed
1941when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2135when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1942C<IO::AIO::munmap> functions are called. 2136or C<IO::AIO::munmap> functions are called on it.
1943 2137
1944This calls the C<mmap>(2) function internally. See your system's manual 2138This calls the C<mmap>(2) function internally. See your system's manual
1945page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2139page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1946 2140
1947The C<$length> must be larger than zero and smaller than the actual 2141The C<$length> must be larger than zero and smaller than the actual
1948filesize. 2142filesize.
1949 2143
1950C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2144C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1951C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2145C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1952 2146
1953C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2147C<$flags> can be a combination of
1954C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2148C<IO::AIO::MAP_SHARED> or
1955not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2149C<IO::AIO::MAP_PRIVATE>,
2150or a number of system-specific flags (when not available, the are C<0>):
1956(which is set to C<MAP_ANON> if your system only provides this 2151C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1957constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2152C<IO::AIO::MAP_LOCKED>,
1958C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2153C<IO::AIO::MAP_NORESERVE>,
2154C<IO::AIO::MAP_POPULATE>,
1959C<IO::AIO::MAP_NONBLOCK> 2155C<IO::AIO::MAP_NONBLOCK>,
2156C<IO::AIO::MAP_FIXED>,
2157C<IO::AIO::MAP_GROWSDOWN>,
2158C<IO::AIO::MAP_32BIT>,
2159C<IO::AIO::MAP_HUGETLB> or
2160C<IO::AIO::MAP_STACK>.
1960 2161
1961If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2162If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1962 2163
1963C<$offset> is the offset from the start of the file - it generally must be 2164C<$offset> is the offset from the start of the file - it generally must be
1964a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2165a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
2007 2208
2008See the C<splice(2)> manpage for details. 2209See the C<splice(2)> manpage for details.
2009 2210
2010=item IO::AIO::tee $r_fh, $w_fh, $length, $flags 2211=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2011 2212
2012Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the 2213Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2013description for C<IO::AIO::splice> above for details. 2214description for C<IO::AIO::splice> above for details.
2215
2216=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2217
2218Attempts to query or change the pipe buffer size. Obviously works only
2219on pipes, and currently works only on GNU/Linux systems, and fails with
2220C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2221size on other systems, drop me a note.
2222
2223=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2224
2225This is a direct interface to the Linux L<pipe2(2)> system call. If
2226C<$flags> is missing or C<0>, then this should be the same as a call to
2227perl's built-in C<pipe> function and create a new pipe, and works on
2228systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2229(..., 4096, O_BINARY)>.
2230
2231If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2232the given flags (Linux 2.6.27, glibc 2.9).
2233
2234On success, the read and write file handles are returned.
2235
2236On error, nothing will be returned. If the pipe2 syscall is missing and
2237C<$flags> is non-zero, fails with C<ENOSYS>.
2238
2239Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2240time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2241C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
2014 2242
2015=back 2243=back
2016 2244
2017=cut 2245=cut
2018 2246

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