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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.225 by root, Tue Apr 10 05:01:33 2012 UTC vs.
Revision 1.268 by root, Tue May 30 22:45:52 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_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
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)
233 aio_mkdir $pathname, $mode, $callback->($status) 238 aio_mkdir $pathname, $mode, $callback->($status)
234 aio_rmdir $pathname, $callback->($status) 239 aio_rmdir $pathname, $callback->($status)
235 aio_readdir $pathname, $callback->($entries) 240 aio_readdir $pathname, $callback->($entries)
236 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 241 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
239 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 244 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
240 aio_load $pathname, $data, $callback->($status) 245 aio_load $pathname, $data, $callback->($status)
241 aio_copy $srcpath, $dstpath, $callback->($status) 246 aio_copy $srcpath, $dstpath, $callback->($status)
242 aio_move $srcpath, $dstpath, $callback->($status) 247 aio_move $srcpath, $dstpath, $callback->($status)
243 aio_rmtree $pathname, $callback->($status) 248 aio_rmtree $pathname, $callback->($status)
249 aio_fcntl $fh, $cmd, $arg, $callback->($status)
250 aio_ioctl $fh, $request, $buf, $callback->($status)
244 aio_sync $callback->($status) 251 aio_sync $callback->($status)
245 aio_syncfs $fh, $callback->($status) 252 aio_syncfs $fh, $callback->($status)
246 aio_fsync $fh, $callback->($status) 253 aio_fsync $fh, $callback->($status)
247 aio_fdatasync $fh, $callback->($status) 254 aio_fdatasync $fh, $callback->($status)
248 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 255 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
249 aio_pathsync $pathname, $callback->($status) 256 aio_pathsync $pathname, $callback->($status)
250 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 257 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
251 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 258 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
252 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 259 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
253 aio_mlockall $flags, $callback->($status) 260 aio_mlockall $flags, $callback->($status)
254 aio_group $callback->(...) 261 aio_group $callback->(...)
255 aio_nop $callback->() 262 aio_nop $callback->()
272 IO::AIO::nready 279 IO::AIO::nready
273 IO::AIO::npending 280 IO::AIO::npending
274 281
275 IO::AIO::sendfile $ofh, $ifh, $offset, $count 282 IO::AIO::sendfile $ofh, $ifh, $offset, $count
276 IO::AIO::fadvise $fh, $offset, $len, $advice 283 IO::AIO::fadvise $fh, $offset, $len, $advice
284 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
285 IO::AIO::munmap $scalar
277 IO::AIO::madvise $scalar, $offset, $length, $advice 286 IO::AIO::madvise $scalar, $offset, $length, $advice
278 IO::AIO::mprotect $scalar, $offset, $length, $protect 287 IO::AIO::mprotect $scalar, $offset, $length, $protect
279 IO::AIO::munlock $scalar, $offset = 0, $length = undef 288 IO::AIO::munlock $scalar, $offset = 0, $length = undef
280 IO::AIO::munlockall 289 IO::AIO::munlockall
281 290
358 367
359 368
360=item aio_open $pathname, $flags, $mode, $callback->($fh) 369=item aio_open $pathname, $flags, $mode, $callback->($fh)
361 370
362Asynchronously open or create a file and call the callback with a newly 371Asynchronously open or create a file and call the callback with a newly
363created filehandle for the file. 372created filehandle for the file (or C<undef> in case of an error).
364 373
365The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 374The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
366for an explanation. 375for an explanation.
367 376
368The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 377The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
391following POSIX and non-POSIX constants are available (missing ones on 400following POSIX and non-POSIX constants are available (missing ones on
392your system are, as usual, C<0>): 401your system are, as usual, C<0>):
393 402
394C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 403C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
395C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 404C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
396C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 405C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
397 406
398 407
399=item aio_close $fh, $callback->($status) 408=item aio_close $fh, $callback->($status)
400 409
401Asynchronously close a file and call the callback with the result 410Asynchronously close a file and call the callback with the result
436=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 445=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
437 446
438=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 447=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
439 448
440Reads or writes C<$length> bytes from or to the specified C<$fh> and 449Reads or writes C<$length> bytes from or to the specified C<$fh> and
441C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 450C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
442and calls the callback without the actual number of bytes read (or -1 on 451calls the callback with the actual number of bytes transferred (or -1 on
443error, just like the syscall). 452error, just like the syscall).
444 453
445C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to 454C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
446offset plus the actual number of bytes read. 455offset plus the actual number of bytes read.
447 456
505As native sendfile syscalls (as practically any non-POSIX interface hacked 514As native sendfile syscalls (as practically any non-POSIX interface hacked
506together in a hurry to improve benchmark numbers) tend to be rather buggy 515together in a hurry to improve benchmark numbers) tend to be rather buggy
507on many systems, this implementation tries to work around some known bugs 516on many systems, this implementation tries to work around some known bugs
508in Linux and FreeBSD kernels (probably others, too), but that might fail, 517in Linux and FreeBSD kernels (probably others, too), but that might fail,
509so you really really should check the return value of C<aio_sendfile> - 518so you really really should check the return value of C<aio_sendfile> -
510fewre bytes than expected might have been transferred. 519fewer bytes than expected might have been transferred.
511 520
512 521
513=item aio_readahead $fh,$offset,$length, $callback->($retval) 522=item aio_readahead $fh,$offset,$length, $callback->($retval)
514 523
515C<aio_readahead> populates the page cache with data from a file so that 524C<aio_readahead> populates the page cache with data from a file so that
519whole pages, so that offset is effectively rounded down to a page boundary 528whole pages, so that offset is effectively rounded down to a page boundary
520and bytes are read up to the next page boundary greater than or equal to 529and bytes are read up to the next page boundary greater than or equal to
521(off-set+length). C<aio_readahead> does not read beyond the end of the 530(off-set+length). C<aio_readahead> does not read beyond the end of the
522file. The current file offset of the file is left unchanged. 531file. The current file offset of the file is left unchanged.
523 532
524If that syscall doesn't exist (likely if your OS isn't Linux) it will be 533If that syscall doesn't exist (likely if your kernel isn't Linux) it will
525emulated by simply reading the data, which would have a similar effect. 534be emulated by simply reading the data, which would have a similar effect.
526 535
527 536
528=item aio_stat $fh_or_path, $callback->($status) 537=item aio_stat $fh_or_path, $callback->($status)
529 538
530=item aio_lstat $fh, $callback->($status) 539=item aio_lstat $fh, $callback->($status)
599 namemax => 255, 608 namemax => 255,
600 frsize => 1024, 609 frsize => 1024,
601 fsid => 1810 610 fsid => 1810
602 } 611 }
603 612
613Here is a (likely partial - send me updates!) list of fsid values used by
614Linux - it is safe to hardcode these when C<$^O> is C<linux>:
615
616 0x0000adf5 adfs
617 0x0000adff affs
618 0x5346414f afs
619 0x09041934 anon-inode filesystem
620 0x00000187 autofs
621 0x42465331 befs
622 0x1badface bfs
623 0x42494e4d binfmt_misc
624 0x9123683e btrfs
625 0x0027e0eb cgroupfs
626 0xff534d42 cifs
627 0x73757245 coda
628 0x012ff7b7 coh
629 0x28cd3d45 cramfs
630 0x453dcd28 cramfs-wend (wrong endianness)
631 0x64626720 debugfs
632 0x00001373 devfs
633 0x00001cd1 devpts
634 0x0000f15f ecryptfs
635 0x00414a53 efs
636 0x0000137d ext
637 0x0000ef53 ext2/ext3/ext4
638 0x0000ef51 ext2
639 0xf2f52010 f2fs
640 0x00004006 fat
641 0x65735546 fuseblk
642 0x65735543 fusectl
643 0x0bad1dea futexfs
644 0x01161970 gfs2
645 0x47504653 gpfs
646 0x00004244 hfs
647 0xf995e849 hpfs
648 0x00c0ffee hostfs
649 0x958458f6 hugetlbfs
650 0x2bad1dea inotifyfs
651 0x00009660 isofs
652 0x000072b6 jffs2
653 0x3153464a jfs
654 0x6b414653 k-afs
655 0x0bd00bd0 lustre
656 0x0000137f minix
657 0x0000138f minix 30 char names
658 0x00002468 minix v2
659 0x00002478 minix v2 30 char names
660 0x00004d5a minix v3
661 0x19800202 mqueue
662 0x00004d44 msdos
663 0x0000564c novell
664 0x00006969 nfs
665 0x6e667364 nfsd
666 0x00003434 nilfs
667 0x5346544e ntfs
668 0x00009fa1 openprom
669 0x7461636F ocfs2
670 0x00009fa0 proc
671 0x6165676c pstorefs
672 0x0000002f qnx4
673 0x68191122 qnx6
674 0x858458f6 ramfs
675 0x52654973 reiserfs
676 0x00007275 romfs
677 0x67596969 rpc_pipefs
678 0x73636673 securityfs
679 0xf97cff8c selinux
680 0x0000517b smb
681 0x534f434b sockfs
682 0x73717368 squashfs
683 0x62656572 sysfs
684 0x012ff7b6 sysv2
685 0x012ff7b5 sysv4
686 0x01021994 tmpfs
687 0x15013346 udf
688 0x00011954 ufs
689 0x54190100 ufs byteswapped
690 0x00009fa2 usbdevfs
691 0x01021997 v9fs
692 0xa501fcf5 vxfs
693 0xabba1974 xenfs
694 0x012ff7b4 xenix
695 0x58465342 xfs
696 0x012fd16d xia
604 697
605=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 698=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
606 699
607Works like perl's C<utime> function (including the special case of $atime 700Works like perl's C<utime> function (including the special case of $atime
608and $mtime being undef). Fractional times are supported if the underlying 701and $mtime being undef). Fractional times are supported if the underlying
636=item aio_truncate $fh_or_path, $offset, $callback->($status) 729=item aio_truncate $fh_or_path, $offset, $callback->($status)
637 730
638Works like truncate(2) or ftruncate(2). 731Works like truncate(2) or ftruncate(2).
639 732
640 733
734=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
735
736Allocates or frees disk space according to the C<$mode> argument. See the
737linux C<fallocate> documentation for details.
738
739C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
740space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
741to deallocate a file range.
742
743IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
744(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
745your L<fallocate(2)> manpage).
746
747The file system block size used by C<fallocate> is presumably the
748C<f_bsize> returned by C<statvfs>.
749
750If C<fallocate> isn't available or cannot be emulated (currently no
751emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
752
753
641=item aio_chmod $fh_or_path, $mode, $callback->($status) 754=item aio_chmod $fh_or_path, $mode, $callback->($status)
642 755
643Works like perl's C<chmod> function. 756Works like perl's C<chmod> function.
644 757
645 758
682 795
683 796
684=item aio_realpath $pathname, $callback->($path) 797=item aio_realpath $pathname, $callback->($path)
685 798
686Asynchronously make the path absolute and resolve any symlinks in 799Asynchronously make the path absolute and resolve any symlinks in
687C<$path>. The resulting path only consists of directories (Same as 800C<$path>. The resulting path only consists of directories (same as
688L<Cwd::realpath>). 801L<Cwd::realpath>).
689 802
690This request can be used to get the absolute path of the current working 803This request can be used to get the absolute path of the current working
691directory by passing it a path of F<.> (a single dot). 804directory by passing it a path of F<.> (a single dot).
692 805
693 806
694=item aio_rename $srcpath, $dstpath, $callback->($status) 807=item aio_rename $srcpath, $dstpath, $callback->($status)
695 808
696Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 809Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
697rename(2) and call the callback with the result code. 810rename(2) and call the callback with the result code.
811
812On systems that support the AIO::WD working directory abstraction
813natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
814of failing, C<rename> is called on the absolute path of C<$wd>.
698 815
699 816
700=item aio_mkdir $pathname, $mode, $callback->($status) 817=item aio_mkdir $pathname, $mode, $callback->($status)
701 818
702Asynchronously mkdir (create) a directory and call the callback with 819Asynchronously mkdir (create) a directory and call the callback with
706 823
707=item aio_rmdir $pathname, $callback->($status) 824=item aio_rmdir $pathname, $callback->($status)
708 825
709Asynchronously rmdir (delete) a directory and call the callback with the 826Asynchronously rmdir (delete) a directory and call the callback with the
710result code. 827result code.
828
829On systems that support the AIO::WD working directory abstraction
830natively, the case C<[$wd, "."]> is specialcased - instead of failing,
831C<rmdir> is called on the absolute path of C<$wd>.
711 832
712 833
713=item aio_readdir $pathname, $callback->($entries) 834=item aio_readdir $pathname, $callback->($entries)
714 835
715Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 836Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
1080} 1201}
1081 1202
1082=item aio_rmtree $pathname, $callback->($status) 1203=item aio_rmtree $pathname, $callback->($status)
1083 1204
1084Delete a directory tree starting (and including) C<$path>, return the 1205Delete a directory tree starting (and including) C<$path>, return the
1085status of the final C<rmdir> only. This is a composite request that 1206status of the final C<rmdir> only. This is a composite request that
1086uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1207uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1087everything else. 1208everything else.
1088 1209
1089=cut 1210=cut
1090 1211
1111 add $grp $dirgrp; 1232 add $grp $dirgrp;
1112 }; 1233 };
1113 1234
1114 $grp 1235 $grp
1115} 1236}
1237
1238=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1239
1240=item aio_ioctl $fh, $request, $buf, $callback->($status)
1241
1242These work just like the C<fcntl> and C<ioctl> built-in functions, except
1243they execute asynchronously and pass the return value to the callback.
1244
1245Both calls can be used for a lot of things, some of which make more sense
1246to run asynchronously in their own thread, while some others make less
1247sense. For example, calls that block waiting for external events, such
1248as locking, will also lock down an I/O thread while it is waiting, which
1249can deadlock the whole I/O system. At the same time, there might be no
1250alternative to using a thread to wait.
1251
1252So in general, you should only use these calls for things that do
1253(filesystem) I/O, not for things that wait for other events (network,
1254other processes), although if you are careful and know what you are doing,
1255you still can.
1256
1257The following constants are available (missing ones are, as usual C<0>):
1258
1259C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1260
1261C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1262C<FS_IOC_FIEMAP>.
1263
1264C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1265C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1266
1267C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1268C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1269C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1270C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1271C<FS_FL_USER_MODIFIABLE>.
1272
1273C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1274C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1275C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1276C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1116 1277
1117=item aio_sync $callback->($status) 1278=item aio_sync $callback->($status)
1118 1279
1119Asynchronously call sync and call the callback when finished. 1280Asynchronously call sync and call the callback when finished.
1120 1281
1189 }; 1350 };
1190 1351
1191 $grp 1352 $grp
1192} 1353}
1193 1354
1194=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1355=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1195 1356
1196This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1357This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1197scalars (see the C<IO::AIO::mmap> function, although it also works on data 1358scalars (see the C<IO::AIO::mmap> function, although it also works on data
1198scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1359scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1199scalar must only be modified in-place while an aio operation is pending on 1360scalar must only be modified in-place while an aio operation is pending on
1201 1362
1202It calls the C<msync> function of your OS, if available, with the memory 1363It calls the C<msync> function of your OS, if available, with the memory
1203area starting at C<$offset> in the string and ending C<$length> bytes 1364area starting at C<$offset> in the string and ending C<$length> bytes
1204later. If C<$length> is negative, counts from the end, and if C<$length> 1365later. If C<$length> is negative, counts from the end, and if C<$length>
1205is C<undef>, then it goes till the end of the string. The flags can be 1366is C<undef>, then it goes till the end of the string. The flags can be
1206a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1367either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1207C<IO::AIO::MS_SYNC>. 1368C<IO::AIO::MS_INVALIDATE>.
1208 1369
1209=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1370=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1210 1371
1211This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1372This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1212scalars. 1373scalars.
1213 1374
1214It touches (reads or writes) all memory pages in the specified 1375It touches (reads or writes) all memory pages in the specified
1215range inside the scalar. All caveats and parameters are the same 1376range inside the scalar. All caveats and parameters are the same
1216as for C<aio_msync>, above, except for flags, which must be either 1377as for C<aio_msync>, above, except for flags, which must be either
1217C<0> (which reads all pages and ensures they are instantiated) or 1378C<0> (which reads all pages and ensures they are instantiated) or
1218C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1379C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1219writing an octet from it, which dirties the page). 1380writing an octet from it, which dirties the page).
1220 1381
1221=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1382=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1222 1383
1223This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1384This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1257 1418
1258 aio_mlockall IO::AIO::MCL_FUTURE; 1419 aio_mlockall IO::AIO::MCL_FUTURE;
1259 1420
1260=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) 1421=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1261 1422
1262Queries the extents of the given file (by calling the Linux FIEMAP ioctl, 1423Queries the extents of the given file (by calling the Linux C<FIEMAP>
1263see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the 1424ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1264C<ioctl> is not available on your OS, then this rquiest will fail with 1425the ioctl is not available on your OS, then this request will fail with
1265C<ENOSYS>. 1426C<ENOSYS>.
1266 1427
1267C<$start> is the starting offset to query extents for, C<$length> is the 1428C<$start> is the starting offset to query extents for, C<$length> is the
1268size of the range to query - if it is C<undef>, then the whole file will 1429size of the range to query - if it is C<undef>, then the whole file will
1269be queried. 1430be queried.
1272C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also 1433C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1273exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query 1434exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1274the data portion. 1435the data portion.
1275 1436
1276C<$count> is the maximum number of extent records to return. If it is 1437C<$count> is the maximum number of extent records to return. If it is
1277C<undef>, then IO::AIO queries all extents of the file. As a very special 1438C<undef>, then IO::AIO queries all extents of the range. As a very special
1278case, if it is C<0>, then the callback receives the number of extents 1439case, if it is C<0>, then the callback receives the number of extents
1279instead of the extents themselves. 1440instead of the extents themselves (which is unreliable, see below).
1280 1441
1281If an error occurs, the callback receives no arguments. The special 1442If an error occurs, the callback receives no arguments. The special
1282C<errno> value C<IO::AIO::EBADR> is available to test for flag errors. 1443C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1283 1444
1284Otherwise, the callback receives an array reference with extent 1445Otherwise, the callback receives an array reference with extent
1286following members: 1447following members:
1287 1448
1288 [$logical, $physical, $length, $flags] 1449 [$logical, $physical, $length, $flags]
1289 1450
1290Flags is any combination of the following flag values (typically either C<0> 1451Flags is any combination of the following flag values (typically either C<0>
1291or C<IO::AIO::FIEMAP_EXTENT_LAST>): 1452or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1292 1453
1293C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>, 1454C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1294C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>, 1455C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1295C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>, 1456C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1296C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>, 1457C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1297C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or 1458C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1298C<IO::AIO::FIEMAP_EXTENT_SHARED>. 1459C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1299 1460
1461At the time of this writing (Linux 3.2), this requets is unreliable unless
1462C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1463it to return all extents of a range for files with large number of
1464extents. The code works around all these issues if C<$count> is undef.
1465
1300=item aio_group $callback->(...) 1466=item aio_group $callback->(...)
1301 1467
1302This is a very special aio request: Instead of doing something, it is a 1468This is a very special aio request: Instead of doing something, it is a
1303container for other aio requests, which is useful if you want to bundle 1469container for other aio requests, which is useful if you want to bundle
1304many requests into a single, composite, request with a definite callback 1470many requests into a single, composite, request with a definite callback
1387 aio_stat [$etcdir, "passwd"], sub { 1553 aio_stat [$etcdir, "passwd"], sub {
1388 # yay 1554 # yay
1389 }; 1555 };
1390 }; 1556 };
1391 1557
1392That C<aio_wd> is a request and not a normal function shows that creating 1558The fact that C<aio_wd> is a request and not a normal function shows that
1393an IO::AIO::WD object is itself a potentially blocking operation, which is 1559creating an IO::AIO::WD object is itself a potentially blocking operation,
1394why it is done asynchronously. 1560which is why it is done asynchronously.
1395 1561
1396To stat the directory obtained with C<aio_wd> above, one could write 1562To stat the directory obtained with C<aio_wd> above, one could write
1397either of the following three request calls: 1563either of the following three request calls:
1398 1564
1399 aio_lstat "/etc" , sub { ... # pathname as normal string 1565 aio_lstat "/etc" , sub { ... # pathname as normal string
1419will still point to the original directory. Most functions accepting a 1585will still point to the original directory. Most functions accepting a
1420pathname will use the directory fd on newer systems, and the string on 1586pathname will use the directory fd on newer systems, and the string on
1421older systems. Some functions (such as realpath) will always rely on the 1587older systems. Some functions (such as realpath) will always rely on the
1422string form of the pathname. 1588string form of the pathname.
1423 1589
1424So this fucntionality is mainly useful to get some protection against 1590So this functionality is mainly useful to get some protection against
1425C<chdir>, to easily get an absolute path out of a relative path for future 1591C<chdir>, to easily get an absolute path out of a relative path for future
1426reference, and to speed up doing many operations in the same directory 1592reference, and to speed up doing many operations in the same directory
1427(e.g. when stat'ing all files in a directory). 1593(e.g. when stat'ing all files in a directory).
1428 1594
1429The following functions implement this working directory abstraction: 1595The following functions implement this working directory abstraction:
1442passing C<undef> as working directory component of a pathname fails the 1608passing C<undef> as working directory component of a pathname fails the
1443request with C<ENOENT>, there is often no need for error checking in the 1609request with C<ENOENT>, there is often no need for error checking in the
1444C<aio_wd> callback, as future requests using the value will fail in the 1610C<aio_wd> callback, as future requests using the value will fail in the
1445expected way. 1611expected way.
1446 1612
1447If this call isn't available because your OS lacks it or it couldn't be
1448detected, it will be emulated by calling C<fsync> instead.
1449
1450=item IO::AIO::CWD 1613=item IO::AIO::CWD
1451 1614
1452This is a compiletime constant (object) that represents the process 1615This is a compiletime constant (object) that represents the process
1453current working directory. 1616current working directory.
1454 1617
1455Specifying this object as working directory object for a pathname is as 1618Specifying this object as working directory object for a pathname is as if
1456if the pathname would be specified directly, without a directory object, 1619the pathname would be specified directly, without a directory object. For
1457e.g., these calls are functionally identical: 1620example, these calls are functionally identical:
1458 1621
1459 aio_stat "somefile", sub { ... }; 1622 aio_stat "somefile", sub { ... };
1460 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1623 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1461 1624
1462=back 1625=back
1463 1626
1627To recover the path associated with an IO::AIO::WD object, you can use
1628C<aio_realpath>:
1629
1630 aio_realpath $wd, sub {
1631 warn "path is $_[0]\n";
1632 };
1633
1634Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1635sometimes, fall back to using an absolue path.
1464 1636
1465=head2 IO::AIO::REQ CLASS 1637=head2 IO::AIO::REQ CLASS
1466 1638
1467All non-aggregate C<aio_*> functions return an object of this class when 1639All non-aggregate C<aio_*> functions return an object of this class when
1468called in non-void context. 1640called in non-void context.
1646 1818
1647See C<poll_cb> for an example. 1819See C<poll_cb> for an example.
1648 1820
1649=item IO::AIO::poll_cb 1821=item IO::AIO::poll_cb
1650 1822
1651Process some outstanding events on the result pipe. You have to call 1823Process some requests that have reached the result phase (i.e. they have
1824been executed but the results are not yet reported). You have to call
1825this "regularly" to finish outstanding requests.
1826
1652this regularly. Returns C<0> if all events could be processed (or there 1827Returns C<0> if all events could be processed (or there were no
1653were no events to process), or C<-1> if it returned earlier for whatever 1828events to process), or C<-1> if it returned earlier for whatever
1654reason. Returns immediately when no events are outstanding. The amount of 1829reason. Returns immediately when no events are outstanding. The amount
1655events processed depends on the settings of C<IO::AIO::max_poll_req> and 1830of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1656C<IO::AIO::max_poll_time>. 1831C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1657 1832
1658If not all requests were processed for whatever reason, the filehandle 1833If not all requests were processed for whatever reason, the poll file
1659will still be ready when C<poll_cb> returns, so normally you don't have to 1834descriptor will still be ready when C<poll_cb> returns, so normally you
1660do anything special to have it called later. 1835don't have to do anything special to have it called later.
1661 1836
1662Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1837Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1663ready, it can be beneficial to call this function from loops which submit 1838ready, it can be beneficial to call this function from loops which submit
1664a lot of requests, to make sure the results get processed when they become 1839a lot of requests, to make sure the results get processed when they become
1665available and not just when the loop is finished and the event loop takes 1840available and not just when the loop is finished and the event loop takes
1674 poll => 'r', async => 1, 1849 poll => 'r', async => 1,
1675 cb => \&IO::AIO::poll_cb); 1850 cb => \&IO::AIO::poll_cb);
1676 1851
1677=item IO::AIO::poll_wait 1852=item IO::AIO::poll_wait
1678 1853
1679If there are any outstanding requests and none of them in the result 1854Wait until either at least one request is in the result phase or no
1680phase, wait till the result filehandle becomes ready for reading (simply 1855requests are outstanding anymore.
1681does a C<select> on the filehandle. This is useful if you want to 1856
1682synchronously wait for some requests to finish). 1857This is useful if you want to synchronously wait for some requests to
1858become ready, without actually handling them.
1683 1859
1684See C<nreqs> for an example. 1860See C<nreqs> for an example.
1685 1861
1686=item IO::AIO::poll 1862=item IO::AIO::poll
1687 1863
1808 1984
1809This is a very bad function to use in interactive programs because it 1985This is a very bad function to use in interactive programs because it
1810blocks, and a bad way to reduce concurrency because it is inexact: Better 1986blocks, and a bad way to reduce concurrency because it is inexact: Better
1811use an C<aio_group> together with a feed callback. 1987use an C<aio_group> together with a feed callback.
1812 1988
1813It's main use is in scripts without an event loop - when you want to stat 1989Its main use is in scripts without an event loop - when you want to stat
1814a lot of files, you can write somehting like this: 1990a lot of files, you can write somehting like this:
1815 1991
1816 IO::AIO::max_outstanding 32; 1992 IO::AIO::max_outstanding 32;
1817 1993
1818 for my $path (...) { 1994 for my $path (...) {
1858 2034
1859=back 2035=back
1860 2036
1861=head3 MISCELLANEOUS FUNCTIONS 2037=head3 MISCELLANEOUS FUNCTIONS
1862 2038
1863IO::AIO implements some functions that might be useful, but are not 2039IO::AIO implements some functions that are useful when you want to use
1864asynchronous. 2040some "Advanced I/O" function not available to in Perl, without going the
2041"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2042counterpart.
1865 2043
1866=over 4 2044=over 4
1867 2045
1868=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2046=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1869 2047
1888=item IO::AIO::madvise $scalar, $offset, $len, $advice 2066=item IO::AIO::madvise $scalar, $offset, $len, $advice
1889 2067
1890Simply calls the C<posix_madvise> function (see its 2068Simply calls the C<posix_madvise> function (see its
1891manpage for details). The following advice constants are 2069manpage for details). The following advice constants are
1892available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2070available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1893C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2071C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
2072C<IO::AIO::MADV_FREE>.
1894 2073
1895On systems that do not implement C<posix_madvise>, this function returns 2074On systems that do not implement C<posix_madvise>, this function returns
1896ENOSYS, otherwise the return value of C<posix_madvise>. 2075ENOSYS, otherwise the return value of C<posix_madvise>.
1897 2076
1898=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2077=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1906ENOSYS, otherwise the return value of C<mprotect>. 2085ENOSYS, otherwise the return value of C<mprotect>.
1907 2086
1908=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2087=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1909 2088
1910Memory-maps a file (or anonymous memory range) and attaches it to the 2089Memory-maps a file (or anonymous memory range) and attaches it to the
1911given C<$scalar>, which will act like a string scalar. 2090given C<$scalar>, which will act like a string scalar. Returns true on
2091success, and false otherwise.
1912 2092
2093The scalar must exist, but its contents do not matter - this means you
2094cannot use a nonexistant array or hash element. When in doubt, C<undef>
2095the scalar first.
2096
1913The only operations allowed on the scalar are C<substr>/C<vec> that don't 2097The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1914change the string length, and most read-only operations such as copying it 2098which don't change the string length, and most read-only operations such
1915or searching it with regexes and so on. 2099as copying it or searching it with regexes and so on.
1916 2100
1917Anything else is unsafe and will, at best, result in memory leaks. 2101Anything else is unsafe and will, at best, result in memory leaks.
1918 2102
1919The memory map associated with the C<$scalar> is automatically removed 2103The memory map associated with the C<$scalar> is automatically removed
1920when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2104when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1921C<IO::AIO::munmap> functions are called. 2105or C<IO::AIO::munmap> functions are called on it.
1922 2106
1923This calls the C<mmap>(2) function internally. See your system's manual 2107This calls the C<mmap>(2) function internally. See your system's manual
1924page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2108page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1925 2109
1926The C<$length> must be larger than zero and smaller than the actual 2110The C<$length> must be larger than zero and smaller than the actual
1927filesize. 2111filesize.
1928 2112
1929C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2113C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1930C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2114C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1931 2115
1932C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2116C<$flags> can be a combination of
1933C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2117C<IO::AIO::MAP_SHARED> or
1934not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2118C<IO::AIO::MAP_PRIVATE>,
2119or a number of system-specific flags (when not available, the are C<0>):
1935(which is set to C<MAP_ANON> if your system only provides this 2120C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1936constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2121C<IO::AIO::MAP_LOCKED>,
1937C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2122C<IO::AIO::MAP_NORESERVE>,
2123C<IO::AIO::MAP_POPULATE>,
1938C<IO::AIO::MAP_NONBLOCK> 2124C<IO::AIO::MAP_NONBLOCK>,
2125C<IO::AIO::MAP_FIXED>,
2126C<IO::AIO::MAP_GROWSDOWN>,
2127C<IO::AIO::MAP_32BIT>,
2128C<IO::AIO::MAP_HUGETLB> or
2129C<IO::AIO::MAP_STACK>.
1939 2130
1940If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2131If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1941 2132
1942C<$offset> is the offset from the start of the file - it generally must be 2133C<$offset> is the offset from the start of the file - it generally must be
1943a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2134a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1975 2166
1976Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or 2167Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
1977C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they 2168C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
1978should be the file offset. 2169should be the file offset.
1979 2170
2171C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2172silently corrupt the data in this case.
2173
1980The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>, 2174The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
1981C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and 2175C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
1982C<IO::AIO::SPLICE_F_GIFT>. 2176C<IO::AIO::SPLICE_F_GIFT>.
1983 2177
1984See the C<splice(2)> manpage for details. 2178See the C<splice(2)> manpage for details.
1985 2179
1986=item IO::AIO::tee $r_fh, $w_fh, $length, $flags 2180=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
1987 2181
1988Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the 2182Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
1989description for C<IO::AIO::splice> above for details. 2183description for C<IO::AIO::splice> above for details.
2184
2185=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2186
2187Attempts to query or change the pipe buffer size. Obviously works only
2188on pipes, and currently works only on GNU/Linux systems, and fails with
2189C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2190size on other systems, drop me a note.
2191
2192=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2193
2194This is a direct interface to the Linux L<pipe2(2)> system call. If
2195C<$flags> is missing or C<0>, then this should be the same as a call to
2196perl's built-in C<pipe> function and create a new pipe, and works on
2197systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2198(..., 4096, O_BINARY)>.
2199
2200If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2201the given flags (Linux 2.6.27, glibc 2.9).
2202
2203On success, the read and write file handles are returned.
2204
2205On error, nothing will be returned. If the pipe2 syscall is missing and
2206C<$flags> is non-zero, fails with C<ENOSYS>.
2207
2208Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2209time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2210C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1990 2211
1991=back 2212=back
1992 2213
1993=cut 2214=cut
1994 2215

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