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Revision 1.228 by root, Sun Jun 17 17:07:25 2012 UTC vs.
Revision 1.272 by root, Fri Jun 23 22:09:50 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);
202 205
203=head1 FUNCTIONS 206=head1 FUNCTIONS
204 207
205=head2 QUICK OVERVIEW 208=head2 QUICK OVERVIEW
206 209
207This section simply lists the prototypes of the most important functions 210This section simply lists the prototypes most of the functions for
208for quick reference. See the following sections for function-by-function 211quick reference. See the following sections for function-by-function
209documentation. 212documentation.
210 213
211 aio_wd $pathname, $callback->($wd) 214 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh) 215 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status) 216 aio_close $fh, $callback->($status)
221 aio_statvfs $fh_or_path, $callback->($statvfs) 224 aio_statvfs $fh_or_path, $callback->($statvfs)
222 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 225 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
223 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 226 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status) 227 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_truncate $fh_or_path, $offset, $callback->($status) 228 aio_truncate $fh_or_path, $offset, $callback->($status)
229 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
230 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
226 aio_unlink $pathname, $callback->($status) 231 aio_unlink $pathname, $callback->($status)
227 aio_mknod $pathname, $mode, $dev, $callback->($status) 232 aio_mknod $pathname, $mode, $dev, $callback->($status)
228 aio_link $srcpath, $dstpath, $callback->($status) 233 aio_link $srcpath, $dstpath, $callback->($status)
229 aio_symlink $srcpath, $dstpath, $callback->($status) 234 aio_symlink $srcpath, $dstpath, $callback->($status)
230 aio_readlink $pathname, $callback->($link) 235 aio_readlink $pathname, $callback->($link)
231 aio_realpath $pathname, $callback->($link) 236 aio_realpath $pathname, $callback->($path)
232 aio_rename $srcpath, $dstpath, $callback->($status) 237 aio_rename $srcpath, $dstpath, $callback->($status)
238 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
233 aio_mkdir $pathname, $mode, $callback->($status) 239 aio_mkdir $pathname, $mode, $callback->($status)
234 aio_rmdir $pathname, $callback->($status) 240 aio_rmdir $pathname, $callback->($status)
235 aio_readdir $pathname, $callback->($entries) 241 aio_readdir $pathname, $callback->($entries)
236 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 242 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
237 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 243 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 245 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
240 aio_load $pathname, $data, $callback->($status) 246 aio_load $pathname, $data, $callback->($status)
241 aio_copy $srcpath, $dstpath, $callback->($status) 247 aio_copy $srcpath, $dstpath, $callback->($status)
242 aio_move $srcpath, $dstpath, $callback->($status) 248 aio_move $srcpath, $dstpath, $callback->($status)
243 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)
244 aio_sync $callback->($status) 252 aio_sync $callback->($status)
245 aio_syncfs $fh, $callback->($status) 253 aio_syncfs $fh, $callback->($status)
246 aio_fsync $fh, $callback->($status) 254 aio_fsync $fh, $callback->($status)
247 aio_fdatasync $fh, $callback->($status) 255 aio_fdatasync $fh, $callback->($status)
248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 256 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
249 aio_pathsync $pathname, $callback->($status) 257 aio_pathsync $pathname, $callback->($status)
250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 258 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 259 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 260 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
253 aio_mlockall $flags, $callback->($status) 261 aio_mlockall $flags, $callback->($status)
254 aio_group $callback->(...) 262 aio_group $callback->(...)
255 aio_nop $callback->() 263 aio_nop $callback->()
360 368
361 369
362=item aio_open $pathname, $flags, $mode, $callback->($fh) 370=item aio_open $pathname, $flags, $mode, $callback->($fh)
363 371
364Asynchronously 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
365created filehandle for the file. 373created filehandle for the file (or C<undef> in case of an error).
366 374
367The 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,
368for an explanation. 376for an explanation.
369 377
370The 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
393following POSIX and non-POSIX constants are available (missing ones on 401following POSIX and non-POSIX constants are available (missing ones on
394your system are, as usual, C<0>): 402your system are, as usual, C<0>):
395 403
396C<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>,
397C<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>,
398C<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>.
399 407
400 408
401=item aio_close $fh, $callback->($status) 409=item aio_close $fh, $callback->($status)
402 410
403Asynchronously close a file and call the callback with the result 411Asynchronously close a file and call the callback with the result
438=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 446=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
439 447
440=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 448=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
441 449
442Reads 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
443C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 451C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
444and 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
445error, just like the syscall). 453error, just like the syscall).
446 454
447C<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
448offset plus the actual number of bytes read. 456offset plus the actual number of bytes read.
449 457
507As native sendfile syscalls (as practically any non-POSIX interface hacked 515As native sendfile syscalls (as practically any non-POSIX interface hacked
508together 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
509on many systems, this implementation tries to work around some known bugs 517on many systems, this implementation tries to work around some known bugs
510in Linux and FreeBSD kernels (probably others, too), but that might fail, 518in Linux and FreeBSD kernels (probably others, too), but that might fail,
511so 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> -
512fewre bytes than expected might have been transferred. 520fewer bytes than expected might have been transferred.
513 521
514 522
515=item aio_readahead $fh,$offset,$length, $callback->($retval) 523=item aio_readahead $fh,$offset,$length, $callback->($retval)
516 524
517C<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
521whole 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
522and 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
523(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
524file. The current file offset of the file is left unchanged. 532file. The current file offset of the file is left unchanged.
525 533
526If 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
527emulated by simply reading the data, which would have a similar effect. 535be emulated by simply reading the data, which would have a similar effect.
528 536
529 537
530=item aio_stat $fh_or_path, $callback->($status) 538=item aio_stat $fh_or_path, $callback->($status)
531 539
532=item aio_lstat $fh, $callback->($status) 540=item aio_lstat $fh, $callback->($status)
601 namemax => 255, 609 namemax => 255,
602 frsize => 1024, 610 frsize => 1024,
603 fsid => 1810 611 fsid => 1810
604 } 612 }
605 613
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
606 698
607=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 699=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
608 700
609Works 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
610and $mtime being undef). Fractional times are supported if the underlying 702and $mtime being undef). Fractional times are supported if the underlying
638=item aio_truncate $fh_or_path, $offset, $callback->($status) 730=item aio_truncate $fh_or_path, $offset, $callback->($status)
639 731
640Works like truncate(2) or ftruncate(2). 732Works like truncate(2) or ftruncate(2).
641 733
642 734
735=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
736
737Allocates or frees disk space according to the C<$mode> argument. See the
738linux C<fallocate> documentation for details.
739
740C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
741space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
742to deallocate a file range.
743
744IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
745(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
746your L<fallocate(2)> manpage).
747
748The file system block size used by C<fallocate> is presumably the
749C<f_bsize> returned by C<statvfs>.
750
751If C<fallocate> isn't available or cannot be emulated (currently no
752emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
753
754
643=item aio_chmod $fh_or_path, $mode, $callback->($status) 755=item aio_chmod $fh_or_path, $mode, $callback->($status)
644 756
645Works like perl's C<chmod> function. 757Works like perl's C<chmod> function.
646 758
647 759
684 796
685 797
686=item aio_realpath $pathname, $callback->($path) 798=item aio_realpath $pathname, $callback->($path)
687 799
688Asynchronously make the path absolute and resolve any symlinks in 800Asynchronously make the path absolute and resolve any symlinks in
689C<$path>. The resulting path only consists of directories (Same as 801C<$path>. The resulting path only consists of directories (same as
690L<Cwd::realpath>). 802L<Cwd::realpath>).
691 803
692This request can be used to get the absolute path of the current working 804This request can be used to get the absolute path of the current working
693directory by passing it a path of F<.> (a single dot). 805directory by passing it a path of F<.> (a single dot).
694 806
695 807
696=item aio_rename $srcpath, $dstpath, $callback->($status) 808=item aio_rename $srcpath, $dstpath, $callback->($status)
697 809
698Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 810Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
699rename(2) and call the callback with the result code. 811rename(2) and call the callback with the result code.
812
813On systems that support the AIO::WD working directory abstraction
814natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
815of failing, C<rename> is called on the absolute path of C<$wd>.
816
817
818=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
819
820Basically a version of C<aio_rename> with an additional C<$flags>
821argument. Calling this with C<$flags=0> is the same as calling
822C<aio_rename>.
823
824Non-zero flags are currently only supported on GNU/Linux systems that
825support renameat2. Other systems fail with C<ENOSYS> in this case.
826
827The following constants are available (missing ones are, as usual C<0>),
828see renameat2(2) for details:
829
830C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
831and C<IO::AIO::RENAME_WHITEOUT>.
700 832
701 833
702=item aio_mkdir $pathname, $mode, $callback->($status) 834=item aio_mkdir $pathname, $mode, $callback->($status)
703 835
704Asynchronously mkdir (create) a directory and call the callback with 836Asynchronously mkdir (create) a directory and call the callback with
708 840
709=item aio_rmdir $pathname, $callback->($status) 841=item aio_rmdir $pathname, $callback->($status)
710 842
711Asynchronously rmdir (delete) a directory and call the callback with the 843Asynchronously rmdir (delete) a directory and call the callback with the
712result code. 844result code.
845
846On systems that support the AIO::WD working directory abstraction
847natively, the case C<[$wd, "."]> is specialcased - instead of failing,
848C<rmdir> is called on the absolute path of C<$wd>.
713 849
714 850
715=item aio_readdir $pathname, $callback->($entries) 851=item aio_readdir $pathname, $callback->($entries)
716 852
717Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 853Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
1082} 1218}
1083 1219
1084=item aio_rmtree $pathname, $callback->($status) 1220=item aio_rmtree $pathname, $callback->($status)
1085 1221
1086Delete a directory tree starting (and including) C<$path>, return the 1222Delete a directory tree starting (and including) C<$path>, return the
1087status of the final C<rmdir> only. This is a composite request that 1223status of the final C<rmdir> only. This is a composite request that
1088uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1224uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1089everything else. 1225everything else.
1090 1226
1091=cut 1227=cut
1092 1228
1113 add $grp $dirgrp; 1249 add $grp $dirgrp;
1114 }; 1250 };
1115 1251
1116 $grp 1252 $grp
1117} 1253}
1254
1255=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1256
1257=item aio_ioctl $fh, $request, $buf, $callback->($status)
1258
1259These work just like the C<fcntl> and C<ioctl> built-in functions, except
1260they execute asynchronously and pass the return value to the callback.
1261
1262Both calls can be used for a lot of things, some of which make more sense
1263to run asynchronously in their own thread, while some others make less
1264sense. For example, calls that block waiting for external events, such
1265as locking, will also lock down an I/O thread while it is waiting, which
1266can deadlock the whole I/O system. At the same time, there might be no
1267alternative to using a thread to wait.
1268
1269So in general, you should only use these calls for things that do
1270(filesystem) I/O, not for things that wait for other events (network,
1271other processes), although if you are careful and know what you are doing,
1272you still can.
1273
1274The following constants are available (missing ones are, as usual C<0>):
1275
1276C<F_DUPFD_CLOEXEC>,
1277
1278C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
1279
1280C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1281
1282C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1283C<FS_IOC_FIEMAP>.
1284
1285C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1286C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1287
1288C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1289C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1290C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1291C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1292C<FS_FL_USER_MODIFIABLE>.
1293
1294C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1295C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1296C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1297C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1118 1298
1119=item aio_sync $callback->($status) 1299=item aio_sync $callback->($status)
1120 1300
1121Asynchronously call sync and call the callback when finished. 1301Asynchronously call sync and call the callback when finished.
1122 1302
1191 }; 1371 };
1192 1372
1193 $grp 1373 $grp
1194} 1374}
1195 1375
1196=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1376=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1197 1377
1198This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1378This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1199scalars (see the C<IO::AIO::mmap> function, although it also works on data 1379scalars (see the C<IO::AIO::mmap> function, although it also works on data
1200scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1380scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1201scalar must only be modified in-place while an aio operation is pending on 1381scalar must only be modified in-place while an aio operation is pending on
1203 1383
1204It calls the C<msync> function of your OS, if available, with the memory 1384It calls the C<msync> function of your OS, if available, with the memory
1205area starting at C<$offset> in the string and ending C<$length> bytes 1385area starting at C<$offset> in the string and ending C<$length> bytes
1206later. If C<$length> is negative, counts from the end, and if C<$length> 1386later. If C<$length> is negative, counts from the end, and if C<$length>
1207is C<undef>, then it goes till the end of the string. The flags can be 1387is C<undef>, then it goes till the end of the string. The flags can be
1208a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1388either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1209C<IO::AIO::MS_SYNC>. 1389C<IO::AIO::MS_INVALIDATE>.
1210 1390
1211=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1391=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1212 1392
1213This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1393This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1214scalars. 1394scalars.
1215 1395
1216It touches (reads or writes) all memory pages in the specified 1396It touches (reads or writes) all memory pages in the specified
1217range inside the scalar. All caveats and parameters are the same 1397range inside the scalar. All caveats and parameters are the same
1218as for C<aio_msync>, above, except for flags, which must be either 1398as for C<aio_msync>, above, except for flags, which must be either
1219C<0> (which reads all pages and ensures they are instantiated) or 1399C<0> (which reads all pages and ensures they are instantiated) or
1220C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1400C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1221writing an octet from it, which dirties the page). 1401writing an octet from it, which dirties the page).
1222 1402
1223=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1403=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1224 1404
1225This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1405This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1259 1439
1260 aio_mlockall IO::AIO::MCL_FUTURE; 1440 aio_mlockall IO::AIO::MCL_FUTURE;
1261 1441
1262=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) 1442=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1263 1443
1264Queries the extents of the given file (by calling the Linux FIEMAP ioctl, 1444Queries the extents of the given file (by calling the Linux C<FIEMAP>
1265see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the 1445ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1266C<ioctl> is not available on your OS, then this rquiest will fail with 1446the ioctl is not available on your OS, then this request will fail with
1267C<ENOSYS>. 1447C<ENOSYS>.
1268 1448
1269C<$start> is the starting offset to query extents for, C<$length> is the 1449C<$start> is the starting offset to query extents for, C<$length> is the
1270size of the range to query - if it is C<undef>, then the whole file will 1450size of the range to query - if it is C<undef>, then the whole file will
1271be queried. 1451be queried.
1274C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also 1454C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1275exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query 1455exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1276the data portion. 1456the data portion.
1277 1457
1278C<$count> is the maximum number of extent records to return. If it is 1458C<$count> is the maximum number of extent records to return. If it is
1279C<undef>, then IO::AIO queries all extents of the file. As a very special 1459C<undef>, then IO::AIO queries all extents of the range. As a very special
1280case, if it is C<0>, then the callback receives the number of extents 1460case, if it is C<0>, then the callback receives the number of extents
1281instead of the extents themselves. 1461instead of the extents themselves (which is unreliable, see below).
1282 1462
1283If an error occurs, the callback receives no arguments. The special 1463If an error occurs, the callback receives no arguments. The special
1284C<errno> value C<IO::AIO::EBADR> is available to test for flag errors. 1464C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1285 1465
1286Otherwise, the callback receives an array reference with extent 1466Otherwise, the callback receives an array reference with extent
1288following members: 1468following members:
1289 1469
1290 [$logical, $physical, $length, $flags] 1470 [$logical, $physical, $length, $flags]
1291 1471
1292Flags is any combination of the following flag values (typically either C<0> 1472Flags is any combination of the following flag values (typically either C<0>
1293or C<IO::AIO::FIEMAP_EXTENT_LAST>): 1473or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1294 1474
1295C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>, 1475C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1296C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>, 1476C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1297C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>, 1477C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1298C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>, 1478C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1299C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or 1479C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1300C<IO::AIO::FIEMAP_EXTENT_SHARED>. 1480C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1301 1481
1482At the time of this writing (Linux 3.2), this requets is unreliable unless
1483C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1484it to return all extents of a range for files with large number of
1485extents. The code works around all these issues if C<$count> is undef.
1486
1302=item aio_group $callback->(...) 1487=item aio_group $callback->(...)
1303 1488
1304This is a very special aio request: Instead of doing something, it is a 1489This is a very special aio request: Instead of doing something, it is a
1305container for other aio requests, which is useful if you want to bundle 1490container for other aio requests, which is useful if you want to bundle
1306many requests into a single, composite, request with a definite callback 1491many requests into a single, composite, request with a definite callback
1389 aio_stat [$etcdir, "passwd"], sub { 1574 aio_stat [$etcdir, "passwd"], sub {
1390 # yay 1575 # yay
1391 }; 1576 };
1392 }; 1577 };
1393 1578
1394That C<aio_wd> is a request and not a normal function shows that creating 1579The fact that C<aio_wd> is a request and not a normal function shows that
1395an IO::AIO::WD object is itself a potentially blocking operation, which is 1580creating an IO::AIO::WD object is itself a potentially blocking operation,
1396why it is done asynchronously. 1581which is why it is done asynchronously.
1397 1582
1398To stat the directory obtained with C<aio_wd> above, one could write 1583To stat the directory obtained with C<aio_wd> above, one could write
1399either of the following three request calls: 1584either of the following three request calls:
1400 1585
1401 aio_lstat "/etc" , sub { ... # pathname as normal string 1586 aio_lstat "/etc" , sub { ... # pathname as normal string
1421will still point to the original directory. Most functions accepting a 1606will still point to the original directory. Most functions accepting a
1422pathname will use the directory fd on newer systems, and the string on 1607pathname will use the directory fd on newer systems, and the string on
1423older systems. Some functions (such as realpath) will always rely on the 1608older systems. Some functions (such as realpath) will always rely on the
1424string form of the pathname. 1609string form of the pathname.
1425 1610
1426So this fucntionality is mainly useful to get some protection against 1611So this functionality is mainly useful to get some protection against
1427C<chdir>, to easily get an absolute path out of a relative path for future 1612C<chdir>, to easily get an absolute path out of a relative path for future
1428reference, and to speed up doing many operations in the same directory 1613reference, and to speed up doing many operations in the same directory
1429(e.g. when stat'ing all files in a directory). 1614(e.g. when stat'ing all files in a directory).
1430 1615
1431The following functions implement this working directory abstraction: 1616The following functions implement this working directory abstraction:
1444passing C<undef> as working directory component of a pathname fails the 1629passing C<undef> as working directory component of a pathname fails the
1445request with C<ENOENT>, there is often no need for error checking in the 1630request with C<ENOENT>, there is often no need for error checking in the
1446C<aio_wd> callback, as future requests using the value will fail in the 1631C<aio_wd> callback, as future requests using the value will fail in the
1447expected way. 1632expected way.
1448 1633
1449If this call isn't available because your OS lacks it or it couldn't be
1450detected, it will be emulated by calling C<fsync> instead.
1451
1452=item IO::AIO::CWD 1634=item IO::AIO::CWD
1453 1635
1454This is a compiletime constant (object) that represents the process 1636This is a compiletime constant (object) that represents the process
1455current working directory. 1637current working directory.
1456 1638
1457Specifying this object as working directory object for a pathname is as 1639Specifying this object as working directory object for a pathname is as if
1458if the pathname would be specified directly, without a directory object, 1640the pathname would be specified directly, without a directory object. For
1459e.g., these calls are functionally identical: 1641example, these calls are functionally identical:
1460 1642
1461 aio_stat "somefile", sub { ... }; 1643 aio_stat "somefile", sub { ... };
1462 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1644 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1463 1645
1464=back 1646=back
1465 1647
1648To recover the path associated with an IO::AIO::WD object, you can use
1649C<aio_realpath>:
1650
1651 aio_realpath $wd, sub {
1652 warn "path is $_[0]\n";
1653 };
1654
1655Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1656sometimes, fall back to using an absolue path.
1466 1657
1467=head2 IO::AIO::REQ CLASS 1658=head2 IO::AIO::REQ CLASS
1468 1659
1469All non-aggregate C<aio_*> functions return an object of this class when 1660All non-aggregate C<aio_*> functions return an object of this class when
1470called in non-void context. 1661called in non-void context.
1648 1839
1649See C<poll_cb> for an example. 1840See C<poll_cb> for an example.
1650 1841
1651=item IO::AIO::poll_cb 1842=item IO::AIO::poll_cb
1652 1843
1653Process some outstanding events on the result pipe. You have to call 1844Process some requests that have reached the result phase (i.e. they have
1845been executed but the results are not yet reported). You have to call
1846this "regularly" to finish outstanding requests.
1847
1654this regularly. Returns C<0> if all events could be processed (or there 1848Returns C<0> if all events could be processed (or there were no
1655were no events to process), or C<-1> if it returned earlier for whatever 1849events to process), or C<-1> if it returned earlier for whatever
1656reason. Returns immediately when no events are outstanding. The amount of 1850reason. Returns immediately when no events are outstanding. The amount
1657events processed depends on the settings of C<IO::AIO::max_poll_req> and 1851of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1658C<IO::AIO::max_poll_time>. 1852C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1659 1853
1660If not all requests were processed for whatever reason, the filehandle 1854If not all requests were processed for whatever reason, the poll file
1661will still be ready when C<poll_cb> returns, so normally you don't have to 1855descriptor will still be ready when C<poll_cb> returns, so normally you
1662do anything special to have it called later. 1856don't have to do anything special to have it called later.
1663 1857
1664Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1858Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1665ready, it can be beneficial to call this function from loops which submit 1859ready, it can be beneficial to call this function from loops which submit
1666a lot of requests, to make sure the results get processed when they become 1860a lot of requests, to make sure the results get processed when they become
1667available and not just when the loop is finished and the event loop takes 1861available and not just when the loop is finished and the event loop takes
1676 poll => 'r', async => 1, 1870 poll => 'r', async => 1,
1677 cb => \&IO::AIO::poll_cb); 1871 cb => \&IO::AIO::poll_cb);
1678 1872
1679=item IO::AIO::poll_wait 1873=item IO::AIO::poll_wait
1680 1874
1681If there are any outstanding requests and none of them in the result 1875Wait until either at least one request is in the result phase or no
1682phase, wait till the result filehandle becomes ready for reading (simply 1876requests are outstanding anymore.
1683does a C<select> on the filehandle. This is useful if you want to 1877
1684synchronously wait for some requests to finish). 1878This is useful if you want to synchronously wait for some requests to
1879become ready, without actually handling them.
1685 1880
1686See C<nreqs> for an example. 1881See C<nreqs> for an example.
1687 1882
1688=item IO::AIO::poll 1883=item IO::AIO::poll
1689 1884
1810 2005
1811This is a very bad function to use in interactive programs because it 2006This is a very bad function to use in interactive programs because it
1812blocks, and a bad way to reduce concurrency because it is inexact: Better 2007blocks, and a bad way to reduce concurrency because it is inexact: Better
1813use an C<aio_group> together with a feed callback. 2008use an C<aio_group> together with a feed callback.
1814 2009
1815It's main use is in scripts without an event loop - when you want to stat 2010Its main use is in scripts without an event loop - when you want to stat
1816a lot of files, you can write somehting like this: 2011a lot of files, you can write somehting like this:
1817 2012
1818 IO::AIO::max_outstanding 32; 2013 IO::AIO::max_outstanding 32;
1819 2014
1820 for my $path (...) { 2015 for my $path (...) {
1860 2055
1861=back 2056=back
1862 2057
1863=head3 MISCELLANEOUS FUNCTIONS 2058=head3 MISCELLANEOUS FUNCTIONS
1864 2059
1865IO::AIO implements some functions that might be useful, but are not 2060IO::AIO implements some functions that are useful when you want to use
1866asynchronous. 2061some "Advanced I/O" function not available to in Perl, without going the
2062"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2063counterpart.
1867 2064
1868=over 4 2065=over 4
1869 2066
1870=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2067=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1871 2068
1890=item IO::AIO::madvise $scalar, $offset, $len, $advice 2087=item IO::AIO::madvise $scalar, $offset, $len, $advice
1891 2088
1892Simply calls the C<posix_madvise> function (see its 2089Simply calls the C<posix_madvise> function (see its
1893manpage for details). The following advice constants are 2090manpage for details). The following advice constants are
1894available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2091available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1895C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2092C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
2093C<IO::AIO::MADV_DONTNEED>.
2094
2095If C<$offset> is negative, counts from the end. If C<$length> is negative,
2096the remaining length of the C<$scalar> is used. If possible, C<$length>
2097will be reduced to fit into the C<$scalar>.
1896 2098
1897On systems that do not implement C<posix_madvise>, this function returns 2099On systems that do not implement C<posix_madvise>, this function returns
1898ENOSYS, otherwise the return value of C<posix_madvise>. 2100ENOSYS, otherwise the return value of C<posix_madvise>.
1899 2101
1900=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2102=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1902Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2104Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1903$scalar (see its manpage for details). The following protect 2105$scalar (see its manpage for details). The following protect
1904constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2106constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1905C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2107C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1906 2108
2109If C<$offset> is negative, counts from the end. If C<$length> is negative,
2110the remaining length of the C<$scalar> is used. If possible, C<$length>
2111will be reduced to fit into the C<$scalar>.
2112
1907On systems that do not implement C<mprotect>, this function returns 2113On systems that do not implement C<mprotect>, this function returns
1908ENOSYS, otherwise the return value of C<mprotect>. 2114ENOSYS, otherwise the return value of C<mprotect>.
1909 2115
1910=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2116=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1911 2117
1912Memory-maps a file (or anonymous memory range) and attaches it to the 2118Memory-maps a file (or anonymous memory range) and attaches it to the
1913given C<$scalar>, which will act like a string scalar. Returns true on 2119given C<$scalar>, which will act like a string scalar. Returns true on
1914success, and false otherwise. 2120success, and false otherwise.
1915 2121
2122The scalar must exist, but its contents do not matter - this means you
2123cannot use a nonexistant array or hash element. When in doubt, C<undef>
2124the scalar first.
2125
1916The only operations allowed on the scalar are C<substr>/C<vec> that don't 2126The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1917change the string length, and most read-only operations such as copying it 2127which don't change the string length, and most read-only operations such
1918or searching it with regexes and so on. 2128as copying it or searching it with regexes and so on.
1919 2129
1920Anything else is unsafe and will, at best, result in memory leaks. 2130Anything else is unsafe and will, at best, result in memory leaks.
1921 2131
1922The memory map associated with the C<$scalar> is automatically removed 2132The memory map associated with the C<$scalar> is automatically removed
1923when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2133when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1924C<IO::AIO::munmap> functions are called. 2134or C<IO::AIO::munmap> functions are called on it.
1925 2135
1926This calls the C<mmap>(2) function internally. See your system's manual 2136This calls the C<mmap>(2) function internally. See your system's manual
1927page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2137page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1928 2138
1929The C<$length> must be larger than zero and smaller than the actual 2139The C<$length> must be larger than zero and smaller than the actual
1930filesize. 2140filesize.
1931 2141
1932C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2142C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1933C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2143C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1934 2144
1935C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2145C<$flags> can be a combination of
1936C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2146C<IO::AIO::MAP_SHARED> or
1937not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2147C<IO::AIO::MAP_PRIVATE>,
2148or a number of system-specific flags (when not available, the are C<0>):
1938(which is set to C<MAP_ANON> if your system only provides this 2149C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1939constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2150C<IO::AIO::MAP_LOCKED>,
1940C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2151C<IO::AIO::MAP_NORESERVE>,
2152C<IO::AIO::MAP_POPULATE>,
1941C<IO::AIO::MAP_NONBLOCK> 2153C<IO::AIO::MAP_NONBLOCK>,
2154C<IO::AIO::MAP_FIXED>,
2155C<IO::AIO::MAP_GROWSDOWN>,
2156C<IO::AIO::MAP_32BIT>,
2157C<IO::AIO::MAP_HUGETLB> or
2158C<IO::AIO::MAP_STACK>.
1942 2159
1943If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2160If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1944 2161
1945C<$offset> is the offset from the start of the file - it generally must be 2162C<$offset> is the offset from the start of the file - it generally must be
1946a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2163a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1989 2206
1990See the C<splice(2)> manpage for details. 2207See the C<splice(2)> manpage for details.
1991 2208
1992=item IO::AIO::tee $r_fh, $w_fh, $length, $flags 2209=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
1993 2210
1994Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the 2211Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
1995description for C<IO::AIO::splice> above for details. 2212description for C<IO::AIO::splice> above for details.
2213
2214=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2215
2216Attempts to query or change the pipe buffer size. Obviously works only
2217on pipes, and currently works only on GNU/Linux systems, and fails with
2218C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2219size on other systems, drop me a note.
2220
2221=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2222
2223This is a direct interface to the Linux L<pipe2(2)> system call. If
2224C<$flags> is missing or C<0>, then this should be the same as a call to
2225perl's built-in C<pipe> function and create a new pipe, and works on
2226systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2227(..., 4096, O_BINARY)>.
2228
2229If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2230the given flags (Linux 2.6.27, glibc 2.9).
2231
2232On success, the read and write file handles are returned.
2233
2234On error, nothing will be returned. If the pipe2 syscall is missing and
2235C<$flags> is non-zero, fails with C<ENOSYS>.
2236
2237Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2238time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2239C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1996 2240
1997=back 2241=back
1998 2242
1999=cut 2243=cut
2000 2244

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