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Revision 1.209 by root, Tue Sep 27 00:41:51 2011 UTC vs.
Revision 1.256 by root, Thu Jun 25 15:47:01 2015 UTC

68=head2 EXAMPLE 68=head2 EXAMPLE
69 69
70This is a simple example that uses the EV module and loads 70This is a simple example that uses the EV module and loads
71F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
72 72
73 use Fcntl;
74 use EV; 73 use EV;
75 use IO::AIO; 74 use IO::AIO;
76 75
77 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
168use common::sense; 167use common::sense;
169 168
170use base 'Exporter'; 169use base 'Exporter';
171 170
172BEGIN { 171BEGIN {
173 our $VERSION = '4.0'; 172 our $VERSION = 4.32;
174 173
175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 174 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 175 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync 176 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate 177 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate
179 aio_pathsync aio_readahead 178 aio_pathsync aio_readahead aio_fiemap
180 aio_rename aio_link aio_move aio_copy aio_group 179 aio_rename aio_link aio_move aio_copy aio_group
181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 180 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182 aio_chmod aio_utime aio_truncate 181 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall 182 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs 183 aio_statvfs
202 201
203=head1 FUNCTIONS 202=head1 FUNCTIONS
204 203
205=head2 QUICK OVERVIEW 204=head2 QUICK OVERVIEW
206 205
207This section simply lists the prototypes of the most important functions 206This section simply lists the prototypes most of the functions for
208for quick reference. See the following sections for function-by-function 207quick reference. See the following sections for function-by-function
209documentation. 208documentation.
210 209
211 aio_wd $pathname, $callback->($wd) 210 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh) 211 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status) 212 aio_close $fh, $callback->($status)
213 aio_seek $fh,$offset,$whence, $callback->($offs)
214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217 aio_readahead $fh,$offset,$length, $callback->($retval) 217 aio_readahead $fh,$offset,$length, $callback->($retval)
218 aio_stat $fh_or_path, $callback->($status) 218 aio_stat $fh_or_path, $callback->($status)
219 aio_lstat $fh, $callback->($status) 219 aio_lstat $fh, $callback->($status)
220 aio_statvfs $fh_or_path, $callback->($statvfs) 220 aio_statvfs $fh_or_path, $callback->($statvfs)
221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 222 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
223 aio_chmod $fh_or_path, $mode, $callback->($status)
223 aio_truncate $fh_or_path, $offset, $callback->($status) 224 aio_truncate $fh_or_path, $offset, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status) 225 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
226 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225 aio_unlink $pathname, $callback->($status) 227 aio_unlink $pathname, $callback->($status)
226 aio_mknod $pathname, $mode, $dev, $callback->($status) 228 aio_mknod $pathname, $mode, $dev, $callback->($status)
227 aio_link $srcpath, $dstpath, $callback->($status) 229 aio_link $srcpath, $dstpath, $callback->($status)
228 aio_symlink $srcpath, $dstpath, $callback->($status) 230 aio_symlink $srcpath, $dstpath, $callback->($status)
229 aio_readlink $pathname, $callback->($link) 231 aio_readlink $pathname, $callback->($link)
230 aio_realpath $pathname, $callback->($link) 232 aio_realpath $pathname, $callback->($path)
231 aio_rename $srcpath, $dstpath, $callback->($status) 233 aio_rename $srcpath, $dstpath, $callback->($status)
232 aio_mkdir $pathname, $mode, $callback->($status) 234 aio_mkdir $pathname, $mode, $callback->($status)
233 aio_rmdir $pathname, $callback->($status) 235 aio_rmdir $pathname, $callback->($status)
234 aio_readdir $pathname, $callback->($entries) 236 aio_readdir $pathname, $callback->($entries)
235 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 237 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 238 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 239 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
240 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238 aio_load $pathname, $data, $callback->($status) 241 aio_load $pathname, $data, $callback->($status)
239 aio_copy $srcpath, $dstpath, $callback->($status) 242 aio_copy $srcpath, $dstpath, $callback->($status)
240 aio_move $srcpath, $dstpath, $callback->($status) 243 aio_move $srcpath, $dstpath, $callback->($status)
241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242 aio_rmtree $pathname, $callback->($status) 244 aio_rmtree $pathname, $callback->($status)
243 aio_sync $callback->($status) 245 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status) 246 aio_syncfs $fh, $callback->($status)
245 aio_fsync $fh, $callback->($status) 247 aio_fsync $fh, $callback->($status)
246 aio_fdatasync $fh, $callback->($status) 248 aio_fdatasync $fh, $callback->($status)
271 IO::AIO::nready 273 IO::AIO::nready
272 IO::AIO::npending 274 IO::AIO::npending
273 275
274 IO::AIO::sendfile $ofh, $ifh, $offset, $count 276 IO::AIO::sendfile $ofh, $ifh, $offset, $count
275 IO::AIO::fadvise $fh, $offset, $len, $advice 277 IO::AIO::fadvise $fh, $offset, $len, $advice
278 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
279 IO::AIO::munmap $scalar
276 IO::AIO::madvise $scalar, $offset, $length, $advice 280 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect 281 IO::AIO::mprotect $scalar, $offset, $length, $protect
278 IO::AIO::munlock $scalar, $offset = 0, $length = undef 282 IO::AIO::munlock $scalar, $offset = 0, $length = undef
279 IO::AIO::munlockall 283 IO::AIO::munlockall
280 284
281=head2 AIO REQUEST FUNCTIONS 285=head2 API NOTES
282 286
283All the C<aio_*> calls are more or less thin wrappers around the syscall 287All the C<aio_*> calls are more or less thin wrappers around the syscall
284with the same name (sans C<aio_>). The arguments are similar or identical, 288with the same name (sans C<aio_>). The arguments are similar or identical,
285and they all accept an additional (and optional) C<$callback> argument 289and they all accept an additional (and optional) C<$callback> argument
286which must be a code reference. This code reference will get called with 290which must be a code reference. This code reference will be called after
287the syscall return code (e.g. most syscalls return C<-1> on error, unlike 291the syscall has been executed in an asynchronous fashion. The results
288perl, which usually delivers "false") as its sole argument after the given 292of the request will be passed as arguments to the callback (and, if an
289syscall has been executed asynchronously. 293error occured, in C<$!>) - for most requests the syscall return code (e.g.
294most syscalls return C<-1> on error, unlike perl, which usually delivers
295"false").
296
297Some requests (such as C<aio_readdir>) pass the actual results and
298communicate failures by passing C<undef>.
290 299
291All functions expecting a filehandle keep a copy of the filehandle 300All functions expecting a filehandle keep a copy of the filehandle
292internally until the request has finished. 301internally until the request has finished.
293 302
294All functions return request objects of type L<IO::AIO::REQ> that allow 303All functions return request objects of type L<IO::AIO::REQ> that allow
295further manipulation of those requests while they are in-flight. 304further manipulation of those requests while they are in-flight.
296 305
297The pathnames you pass to these routines I<should> be absolute. The 306The pathnames you pass to these routines I<should> be absolute. The
298reason for this is that at the time the request is being executed, the 307reason for this is that at the time the request is being executed, the
299current working directory could have changed. Alternatively, you can make 308current working directory could have changed. Alternatively, you can
300sure that you never change the current working directory anywhere in 309make sure that you never change the current working directory anywhere
301the program and then use relative paths. Lastly, you can take advantage 310in the program and then use relative paths. You can also take advantage
302of IO::AIOs working directory abstraction - see the description of the 311of IO::AIOs working directory abstraction, that lets you specify paths
312relative to some previously-opened "working directory object" - see the
303C<IO::AIO::WD> class later in this document. 313description of the C<IO::AIO::WD> class later in this document.
304 314
305To encode pathnames as octets, either make sure you either: a) always pass 315To encode pathnames as octets, either make sure you either: a) always pass
306in filenames you got from outside (command line, readdir etc.) without 316in filenames you got from outside (command line, readdir etc.) without
307tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 317tinkering, b) are in your native filesystem encoding, c) use the Encode
308your pathnames to the locale (or other) encoding in effect in the user 318module and encode your pathnames to the locale (or other) encoding in
309environment, d) use Glib::filename_from_unicode on unicode filenames or e) 319effect in the user environment, d) use Glib::filename_from_unicode on
310use something else to ensure your scalar has the correct contents. 320unicode filenames or e) use something else to ensure your scalar has the
321correct contents.
311 322
312This works, btw. independent of the internal UTF-8 bit, which IO::AIO 323This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313handles correctly whether it is set or not. 324handles correctly whether it is set or not.
325
326=head2 AIO REQUEST FUNCTIONS
314 327
315=over 4 328=over 4
316 329
317=item $prev_pri = aioreq_pri [$pri] 330=item $prev_pri = aioreq_pri [$pri]
318 331
348 361
349 362
350=item aio_open $pathname, $flags, $mode, $callback->($fh) 363=item aio_open $pathname, $flags, $mode, $callback->($fh)
351 364
352Asynchronously open or create a file and call the callback with a newly 365Asynchronously open or create a file and call the callback with a newly
353created filehandle for the file. 366created filehandle for the file (or C<undef> in case of an error).
354 367
355The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 368The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356for an explanation. 369for an explanation.
357 370
358The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 371The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
381following POSIX and non-POSIX constants are available (missing ones on 394following POSIX and non-POSIX constants are available (missing ones on
382your system are, as usual, C<0>): 395your system are, as usual, C<0>):
383 396
384C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 397C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 398C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 399C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
387 400
388 401
389=item aio_close $fh, $callback->($status) 402=item aio_close $fh, $callback->($status)
390 403
391Asynchronously close a file and call the callback with the result 404Asynchronously close a file and call the callback with the result
400 413
401Or in other words: the file descriptor will be closed, but it will not be 414Or in other words: the file descriptor will be closed, but it will not be
402free for reuse until the perl filehandle is closed. 415free for reuse until the perl filehandle is closed.
403 416
404=cut 417=cut
418
419=item aio_seek $fh, $offset, $whence, $callback->($offs)
420
421Seeks the filehandle to the new C<$offset>, similarly to perl's
422C<sysseek>. The C<$whence> can use the traditional values (C<0> for
423C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
424C<IO::AIO::SEEK_END>).
425
426The resulting absolute offset will be passed to the callback, or C<-1> in
427case of an error.
428
429In theory, the C<$whence> constants could be different than the
430corresponding values from L<Fcntl>, but perl guarantees they are the same,
431so don't panic.
432
433As a GNU/Linux (and maybe Solaris) extension, also the constants
434C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
435could be found. No guarantees about suitability for use in C<aio_seek> or
436Perl's C<sysseek> can be made though, although I would naively assume they
437"just work".
405 438
406=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 439=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407 440
408=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 441=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409 442
569 namemax => 255, 602 namemax => 255,
570 frsize => 1024, 603 frsize => 1024,
571 fsid => 1810 604 fsid => 1810
572 } 605 }
573 606
607Here is a (likely partial - send me updates!) list of fsid values used by
608Linux - it is safe to hardcode these when C<$^O> is C<linux>:
609
610 0x0000adf5 adfs
611 0x0000adff affs
612 0x5346414f afs
613 0x09041934 anon-inode filesystem
614 0x00000187 autofs
615 0x42465331 befs
616 0x1badface bfs
617 0x42494e4d binfmt_misc
618 0x9123683e btrfs
619 0x0027e0eb cgroupfs
620 0xff534d42 cifs
621 0x73757245 coda
622 0x012ff7b7 coh
623 0x28cd3d45 cramfs
624 0x453dcd28 cramfs-wend (wrong endianness)
625 0x64626720 debugfs
626 0x00001373 devfs
627 0x00001cd1 devpts
628 0x0000f15f ecryptfs
629 0x00414a53 efs
630 0x0000137d ext
631 0x0000ef53 ext2/ext3
632 0x0000ef51 ext2
633 0x00004006 fat
634 0x65735546 fuseblk
635 0x65735543 fusectl
636 0x0bad1dea futexfs
637 0x01161970 gfs2
638 0x47504653 gpfs
639 0x00004244 hfs
640 0xf995e849 hpfs
641 0x958458f6 hugetlbfs
642 0x2bad1dea inotifyfs
643 0x00009660 isofs
644 0x000072b6 jffs2
645 0x3153464a jfs
646 0x6b414653 k-afs
647 0x0bd00bd0 lustre
648 0x0000137f minix
649 0x0000138f minix 30 char names
650 0x00002468 minix v2
651 0x00002478 minix v2 30 char names
652 0x00004d5a minix v3
653 0x19800202 mqueue
654 0x00004d44 msdos
655 0x0000564c novell
656 0x00006969 nfs
657 0x6e667364 nfsd
658 0x00003434 nilfs
659 0x5346544e ntfs
660 0x00009fa1 openprom
661 0x7461636F ocfs2
662 0x00009fa0 proc
663 0x6165676c pstorefs
664 0x0000002f qnx4
665 0x858458f6 ramfs
666 0x52654973 reiserfs
667 0x00007275 romfs
668 0x67596969 rpc_pipefs
669 0x73636673 securityfs
670 0xf97cff8c selinux
671 0x0000517b smb
672 0x534f434b sockfs
673 0x73717368 squashfs
674 0x62656572 sysfs
675 0x012ff7b6 sysv2
676 0x012ff7b5 sysv4
677 0x01021994 tmpfs
678 0x15013346 udf
679 0x00011954 ufs
680 0x54190100 ufs byteswapped
681 0x00009fa2 usbdevfs
682 0x01021997 v9fs
683 0xa501fcf5 vxfs
684 0xabba1974 xenfs
685 0x012ff7b4 xenix
686 0x58465342 xfs
687 0x012fd16d xia
574 688
575=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 689=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576 690
577Works like perl's C<utime> function (including the special case of $atime 691Works like perl's C<utime> function (including the special case of $atime
578and $mtime being undef). Fractional times are supported if the underlying 692and $mtime being undef). Fractional times are supported if the underlying
606=item aio_truncate $fh_or_path, $offset, $callback->($status) 720=item aio_truncate $fh_or_path, $offset, $callback->($status)
607 721
608Works like truncate(2) or ftruncate(2). 722Works like truncate(2) or ftruncate(2).
609 723
610 724
725=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
726
727Allocates or frees disk space according to the C<$mode> argument. See the
728linux C<fallocate> documentation for details.
729
730C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
731space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
732to deallocate a file range.
733
734IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
735(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
736your L<fallocate(2)> manpage).
737
738The file system block size used by C<fallocate> is presumably the
739C<f_bsize> returned by C<statvfs>.
740
741If C<fallocate> isn't available or cannot be emulated (currently no
742emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
743
744
611=item aio_chmod $fh_or_path, $mode, $callback->($status) 745=item aio_chmod $fh_or_path, $mode, $callback->($status)
612 746
613Works like perl's C<chmod> function. 747Works like perl's C<chmod> function.
614 748
615 749
652 786
653 787
654=item aio_realpath $pathname, $callback->($path) 788=item aio_realpath $pathname, $callback->($path)
655 789
656Asynchronously make the path absolute and resolve any symlinks in 790Asynchronously make the path absolute and resolve any symlinks in
657C<$path>. The resulting path only consists of directories (Same as 791C<$path>. The resulting path only consists of directories (same as
658L<Cwd::realpath>). 792L<Cwd::realpath>).
659 793
660This request can be used to get the absolute path of the current working 794This request can be used to get the absolute path of the current working
661directory by passing it a path of F<.> (a single dot). 795directory by passing it a path of F<.> (a single dot).
662 796
663 797
664=item aio_rename $srcpath, $dstpath, $callback->($status) 798=item aio_rename $srcpath, $dstpath, $callback->($status)
665 799
666Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 800Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667rename(2) and call the callback with the result code. 801rename(2) and call the callback with the result code.
802
803On systems that support the AIO::WD working directory abstraction
804natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
805of failing, C<rename> is called on the absolute path of C<$wd>.
668 806
669 807
670=item aio_mkdir $pathname, $mode, $callback->($status) 808=item aio_mkdir $pathname, $mode, $callback->($status)
671 809
672Asynchronously mkdir (create) a directory and call the callback with 810Asynchronously mkdir (create) a directory and call the callback with
676 814
677=item aio_rmdir $pathname, $callback->($status) 815=item aio_rmdir $pathname, $callback->($status)
678 816
679Asynchronously rmdir (delete) a directory and call the callback with the 817Asynchronously rmdir (delete) a directory and call the callback with the
680result code. 818result code.
819
820On systems that support the AIO::WD working directory abstraction
821natively, the case C<[$wd, "."]> is specialcased - instead of failing,
822C<rmdir> is called on the absolute path of C<$wd>.
681 823
682 824
683=item aio_readdir $pathname, $callback->($entries) 825=item aio_readdir $pathname, $callback->($entries)
684 826
685Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 827Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
966 1108
967 my $grp = aio_group $cb; 1109 my $grp = aio_group $cb;
968 1110
969 $maxreq = 4 if $maxreq <= 0; 1111 $maxreq = 4 if $maxreq <= 0;
970 1112
971 # stat once 1113 # get a wd object
972 aioreq_pri $pri; 1114 aioreq_pri $pri;
973 add $grp aio_stat $path, sub { 1115 add $grp aio_wd $path, sub {
1116 $_[0]
974 return $grp->result () if $_[0]; 1117 or return $grp->result ();
975 my $now = time;
976 my $hash1 = join ":", (stat _)[0,1,3,7,9];
977 1118
978 # read the directory entries 1119 my $wd = [shift, "."];
1120
1121 # stat once
979 aioreq_pri $pri; 1122 aioreq_pri $pri;
980 add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { 1123 add $grp aio_stat $wd, sub {
981 my $entries = shift
982 or return $grp->result (); 1124 return $grp->result () if $_[0];
1125 my $now = time;
1126 my $hash1 = join ":", (stat _)[0,1,3,7,9];
983 1127
984 # stat the dir another time 1128 # read the directory entries
985 aioreq_pri $pri; 1129 aioreq_pri $pri;
1130 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
1131 my $entries = shift
1132 or return $grp->result ();
1133
1134 # stat the dir another time
1135 aioreq_pri $pri;
986 add $grp aio_stat $path, sub { 1136 add $grp aio_stat $wd, sub {
987 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1137 my $hash2 = join ":", (stat _)[0,1,3,7,9];
988 1138
989 my $ndirs; 1139 my $ndirs;
990 1140
991 # take the slow route if anything looks fishy 1141 # take the slow route if anything looks fishy
992 if ($hash1 ne $hash2 or (stat _)[9] == $now) { 1142 if ($hash1 ne $hash2 or (stat _)[9] == $now) {
993 $ndirs = -1; 1143 $ndirs = -1;
994 } else { 1144 } else {
995 # if nlink == 2, we are finished 1145 # if nlink == 2, we are finished
996 # for non-posix-fs's, we rely on nlink < 2 1146 # for non-posix-fs's, we rely on nlink < 2
997 $ndirs = (stat _)[3] - 2 1147 $ndirs = (stat _)[3] - 2
998 or return $grp->result ([], $entries); 1148 or return $grp->result ([], $entries);
999 } 1149 }
1000 1150
1001 my (@dirs, @nondirs); 1151 my (@dirs, @nondirs);
1002 1152
1003 my $statgrp = add $grp aio_group sub { 1153 my $statgrp = add $grp aio_group sub {
1004 $grp->result (\@dirs, \@nondirs); 1154 $grp->result (\@dirs, \@nondirs);
1005 }; 1155 };
1006 1156
1007 limit $statgrp $maxreq; 1157 limit $statgrp $maxreq;
1008 feed $statgrp sub { 1158 feed $statgrp sub {
1009 return unless @$entries; 1159 return unless @$entries;
1010 my $entry = shift @$entries; 1160 my $entry = shift @$entries;
1011 1161
1012 aioreq_pri $pri; 1162 aioreq_pri $pri;
1163 $wd->[1] = "$entry/.";
1013 add $statgrp aio_stat "$path/$entry/.", sub { 1164 add $statgrp aio_stat $wd, sub {
1014 if ($_[0] < 0) { 1165 if ($_[0] < 0) {
1015 push @nondirs, $entry; 1166 push @nondirs, $entry;
1016 } else { 1167 } else {
1017 # need to check for real directory 1168 # need to check for real directory
1018 aioreq_pri $pri; 1169 aioreq_pri $pri;
1170 $wd->[1] = $entry;
1019 add $statgrp aio_lstat "$path/$entry", sub { 1171 add $statgrp aio_lstat $wd, sub {
1020 if (-d _) { 1172 if (-d _) {
1021 push @dirs, $entry; 1173 push @dirs, $entry;
1022 1174
1023 unless (--$ndirs) { 1175 unless (--$ndirs) {
1024 push @nondirs, @$entries; 1176 push @nondirs, @$entries;
1025 feed $statgrp; 1177 feed $statgrp;
1178 }
1179 } else {
1180 push @nondirs, $entry;
1026 } 1181 }
1027 } else {
1028 push @nondirs, $entry;
1029 } 1182 }
1030 } 1183 }
1031 } 1184 };
1032 }; 1185 };
1033 }; 1186 };
1034 }; 1187 };
1035 }; 1188 };
1036 }; 1189 };
1039} 1192}
1040 1193
1041=item aio_rmtree $pathname, $callback->($status) 1194=item aio_rmtree $pathname, $callback->($status)
1042 1195
1043Delete a directory tree starting (and including) C<$path>, return the 1196Delete a directory tree starting (and including) C<$path>, return the
1044status of the final C<rmdir> only. This is a composite request that 1197status of the final C<rmdir> only. This is a composite request that
1045uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1198uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1046everything else. 1199everything else.
1047 1200
1048=cut 1201=cut
1049 1202
1169 1322
1170This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1323This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1171scalars. 1324scalars.
1172 1325
1173It touches (reads or writes) all memory pages in the specified 1326It touches (reads or writes) all memory pages in the specified
1174range inside the scalar. All caveats and parameters are the same 1327range inside the scalar. All caveats and parameters are the same
1175as for C<aio_msync>, above, except for flags, which must be either 1328as for C<aio_msync>, above, except for flags, which must be either
1176C<0> (which reads all pages and ensures they are instantiated) or 1329C<0> (which reads all pages and ensures they are instantiated) or
1177C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1330C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1178writing an octet from it, which dirties the page). 1331writing an octet from it, which dirties the page).
1179 1332
1180=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1333=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1181 1334
1182This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1335This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1213documented under L<MISCELLANEOUS FUNCTIONS>. 1366documented under L<MISCELLANEOUS FUNCTIONS>.
1214 1367
1215Example: asynchronously lock all current and future pages into memory. 1368Example: asynchronously lock all current and future pages into memory.
1216 1369
1217 aio_mlockall IO::AIO::MCL_FUTURE; 1370 aio_mlockall IO::AIO::MCL_FUTURE;
1371
1372=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1373
1374Queries the extents of the given file (by calling the Linux C<FIEMAP>
1375ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1376the ioctl is not available on your OS, then this request will fail with
1377C<ENOSYS>.
1378
1379C<$start> is the starting offset to query extents for, C<$length> is the
1380size of the range to query - if it is C<undef>, then the whole file will
1381be queried.
1382
1383C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1384C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1385exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1386the data portion.
1387
1388C<$count> is the maximum number of extent records to return. If it is
1389C<undef>, then IO::AIO queries all extents of the range. As a very special
1390case, if it is C<0>, then the callback receives the number of extents
1391instead of the extents themselves (which is unreliable, see below).
1392
1393If an error occurs, the callback receives no arguments. The special
1394C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1395
1396Otherwise, the callback receives an array reference with extent
1397structures. Each extent structure is an array reference itself, with the
1398following members:
1399
1400 [$logical, $physical, $length, $flags]
1401
1402Flags is any combination of the following flag values (typically either C<0>
1403or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1404
1405C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1406C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1407C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1408C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1409C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1410C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1411
1412At the time of this writing (Linux 3.2), this requets is unreliable unless
1413C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1414it to return all extents of a range for files with large number of
1415extents. The code works around all these issues if C<$count> is undef.
1218 1416
1219=item aio_group $callback->(...) 1417=item aio_group $callback->(...)
1220 1418
1221This is a very special aio request: Instead of doing something, it is a 1419This is a very special aio request: Instead of doing something, it is a
1222container for other aio requests, which is useful if you want to bundle 1420container for other aio requests, which is useful if you want to bundle
1286object. This object stores the canonicalised, absolute version of the 1484object. This object stores the canonicalised, absolute version of the
1287path, and on systems that allow it, also a directory file descriptor. 1485path, and on systems that allow it, also a directory file descriptor.
1288 1486
1289Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat> 1487Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1290or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD 1488or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1291object and a pathname instead. If the pathname is absolute, the 1489object and a pathname instead (or the IO::AIO::WD object alone, which
1490gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1292IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative 1491IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1293to that IO::AIO::WD object. 1492to that IO::AIO::WD object.
1294 1493
1295For example, to get a wd object for F</etc> and then stat F<passwd> 1494For example, to get a wd object for F</etc> and then stat F<passwd>
1296inside, you would write: 1495inside, you would write:
1297 1496
1305 aio_stat [$etcdir, "passwd"], sub { 1504 aio_stat [$etcdir, "passwd"], sub {
1306 # yay 1505 # yay
1307 }; 1506 };
1308 }; 1507 };
1309 1508
1509The fact that C<aio_wd> is a request and not a normal function shows that
1310This shows that creating an IO::AIO::WD object is itself a potentially 1510creating an IO::AIO::WD object is itself a potentially blocking operation,
1311blocking operation, which is why it is done asynchronously. 1511which is why it is done asynchronously.
1512
1513To stat the directory obtained with C<aio_wd> above, one could write
1514either of the following three request calls:
1515
1516 aio_lstat "/etc" , sub { ... # pathname as normal string
1517 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1518 aio_lstat $wd , sub { ... # shorthand for the previous
1312 1519
1313As with normal pathnames, IO::AIO keeps a copy of the working directory 1520As with normal pathnames, IO::AIO keeps a copy of the working directory
1314object and the pathname string, so you could write the following without 1521object and the pathname string, so you could write the following without
1315causing any issues due to C<$path> getting reused: 1522causing any issues due to C<$path> getting reused:
1316 1523
1329will still point to the original directory. Most functions accepting a 1536will still point to the original directory. Most functions accepting a
1330pathname will use the directory fd on newer systems, and the string on 1537pathname will use the directory fd on newer systems, and the string on
1331older systems. Some functions (such as realpath) will always rely on the 1538older systems. Some functions (such as realpath) will always rely on the
1332string form of the pathname. 1539string form of the pathname.
1333 1540
1334So this fucntionality is mainly useful to get some protection against 1541So this functionality is mainly useful to get some protection against
1335C<chdir>, to easily get an absolute path out of a relative path for future 1542C<chdir>, to easily get an absolute path out of a relative path for future
1336reference, and to speed up doing many operations in the same directory 1543reference, and to speed up doing many operations in the same directory
1337(e.g. when stat'ing all files in a directory). 1544(e.g. when stat'ing all files in a directory).
1338 1545
1339The following functions implement this working directory abstraction: 1546The following functions implement this working directory abstraction:
1352passing C<undef> as working directory component of a pathname fails the 1559passing C<undef> as working directory component of a pathname fails the
1353request with C<ENOENT>, there is often no need for error checking in the 1560request with C<ENOENT>, there is often no need for error checking in the
1354C<aio_wd> callback, as future requests using the value will fail in the 1561C<aio_wd> callback, as future requests using the value will fail in the
1355expected way. 1562expected way.
1356 1563
1357If this call isn't available because your OS lacks it or it couldn't be
1358detected, it will be emulated by calling C<fsync> instead.
1359
1360=item IO::AIO::CWD 1564=item IO::AIO::CWD
1361 1565
1362This is a compiletime constant (object) that represents the process 1566This is a compiletime constant (object) that represents the process
1363current working directory. 1567current working directory.
1364 1568
1365Specifying this object as working directory object for a pathname is as 1569Specifying this object as working directory object for a pathname is as if
1366if the pathname would be specified directly, without a directory object, 1570the pathname would be specified directly, without a directory object. For
1367e.g., these calls are functionally identical: 1571example, these calls are functionally identical:
1368 1572
1369 aio_stat "somefile", sub { ... }; 1573 aio_stat "somefile", sub { ... };
1370 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1574 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1371 1575
1372=back 1576=back
1373 1577
1578To recover the path associated with an IO::AIO::WD object, you can use
1579C<aio_realpath>:
1580
1581 aio_realpath $wd, sub {
1582 warn "path is $_[0]\n";
1583 };
1584
1585Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1586sometimes, fall back to using an absolue path.
1374 1587
1375=head2 IO::AIO::REQ CLASS 1588=head2 IO::AIO::REQ CLASS
1376 1589
1377All non-aggregate C<aio_*> functions return an object of this class when 1590All non-aggregate C<aio_*> functions return an object of this class when
1378called in non-void context. 1591called in non-void context.
1496 1709
1497Sets a feeder/generator on this group: every group can have an attached 1710Sets a feeder/generator on this group: every group can have an attached
1498generator that generates requests if idle. The idea behind this is that, 1711generator that generates requests if idle. The idea behind this is that,
1499although you could just queue as many requests as you want in a group, 1712although you could just queue as many requests as you want in a group,
1500this might starve other requests for a potentially long time. For example, 1713this might starve other requests for a potentially long time. For example,
1501C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests, 1714C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1502delaying any later requests for a long time. 1715requests, delaying any later requests for a long time.
1503 1716
1504To avoid this, and allow incremental generation of requests, you can 1717To avoid this, and allow incremental generation of requests, you can
1505instead a group and set a feeder on it that generates those requests. The 1718instead a group and set a feeder on it that generates those requests. The
1506feed callback will be called whenever there are few enough (see C<limit>, 1719feed callback will be called whenever there are few enough (see C<limit>,
1507below) requests active in the group itself and is expected to queue more 1720below) requests active in the group itself and is expected to queue more
1556 1769
1557See C<poll_cb> for an example. 1770See C<poll_cb> for an example.
1558 1771
1559=item IO::AIO::poll_cb 1772=item IO::AIO::poll_cb
1560 1773
1561Process some outstanding events on the result pipe. You have to call 1774Process some requests that have reached the result phase (i.e. they have
1775been executed but the results are not yet reported). You have to call
1776this "regularly" to finish outstanding requests.
1777
1562this regularly. Returns C<0> if all events could be processed (or there 1778Returns C<0> if all events could be processed (or there were no
1563were no events to process), or C<-1> if it returned earlier for whatever 1779events to process), or C<-1> if it returned earlier for whatever
1564reason. Returns immediately when no events are outstanding. The amount of 1780reason. Returns immediately when no events are outstanding. The amount
1565events processed depends on the settings of C<IO::AIO::max_poll_req> and 1781of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1566C<IO::AIO::max_poll_time>. 1782C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1567 1783
1568If not all requests were processed for whatever reason, the filehandle 1784If not all requests were processed for whatever reason, the poll file
1569will still be ready when C<poll_cb> returns, so normally you don't have to 1785descriptor will still be ready when C<poll_cb> returns, so normally you
1570do anything special to have it called later. 1786don't have to do anything special to have it called later.
1571 1787
1572Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1788Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1573ready, it can be beneficial to call this function from loops which submit 1789ready, it can be beneficial to call this function from loops which submit
1574a lot of requests, to make sure the results get processed when they become 1790a lot of requests, to make sure the results get processed when they become
1575available and not just when the loop is finished and the event loop takes 1791available and not just when the loop is finished and the event loop takes
1584 poll => 'r', async => 1, 1800 poll => 'r', async => 1,
1585 cb => \&IO::AIO::poll_cb); 1801 cb => \&IO::AIO::poll_cb);
1586 1802
1587=item IO::AIO::poll_wait 1803=item IO::AIO::poll_wait
1588 1804
1589If there are any outstanding requests and none of them in the result 1805Wait until either at least one request is in the result phase or no
1590phase, wait till the result filehandle becomes ready for reading (simply 1806requests are outstanding anymore.
1591does a C<select> on the filehandle. This is useful if you want to 1807
1592synchronously wait for some requests to finish). 1808This is useful if you want to synchronously wait for some requests to
1809become ready, without actually handling them.
1593 1810
1594See C<nreqs> for an example. 1811See C<nreqs> for an example.
1595 1812
1596=item IO::AIO::poll 1813=item IO::AIO::poll
1597 1814
1718 1935
1719This is a very bad function to use in interactive programs because it 1936This is a very bad function to use in interactive programs because it
1720blocks, and a bad way to reduce concurrency because it is inexact: Better 1937blocks, and a bad way to reduce concurrency because it is inexact: Better
1721use an C<aio_group> together with a feed callback. 1938use an C<aio_group> together with a feed callback.
1722 1939
1723It's main use is in scripts without an event loop - when you want to stat 1940Its main use is in scripts without an event loop - when you want to stat
1724a lot of files, you can write somehting like this: 1941a lot of files, you can write somehting like this:
1725 1942
1726 IO::AIO::max_outstanding 32; 1943 IO::AIO::max_outstanding 32;
1727 1944
1728 for my $path (...) { 1945 for my $path (...) {
1768 1985
1769=back 1986=back
1770 1987
1771=head3 MISCELLANEOUS FUNCTIONS 1988=head3 MISCELLANEOUS FUNCTIONS
1772 1989
1773IO::AIO implements some functions that might be useful, but are not 1990IO::AIO implements some functions that are useful when you want to use
1774asynchronous. 1991some "Advanced I/O" function not available to in Perl, without going the
1992"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
1993counterpart.
1775 1994
1776=over 4 1995=over 4
1777 1996
1778=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 1997=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1779 1998
1816ENOSYS, otherwise the return value of C<mprotect>. 2035ENOSYS, otherwise the return value of C<mprotect>.
1817 2036
1818=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2037=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1819 2038
1820Memory-maps a file (or anonymous memory range) and attaches it to the 2039Memory-maps a file (or anonymous memory range) and attaches it to the
1821given C<$scalar>, which will act like a string scalar. 2040given C<$scalar>, which will act like a string scalar. Returns true on
2041success, and false otherwise.
1822 2042
1823The only operations allowed on the scalar are C<substr>/C<vec> that don't 2043The only operations allowed on the scalar are C<substr>/C<vec> that don't
1824change the string length, and most read-only operations such as copying it 2044change the string length, and most read-only operations such as copying it
1825or searching it with regexes and so on. 2045or searching it with regexes and so on.
1826 2046
1837filesize. 2057filesize.
1838 2058
1839C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2059C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1840C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2060C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1841 2061
1842C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2062C<$flags> can be a combination of
1843C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2063C<IO::AIO::MAP_SHARED> or
1844not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2064C<IO::AIO::MAP_PRIVATE>,
2065or a number of system-specific flags (when not available, the are C<0>):
1845(which is set to C<MAP_ANON> if your system only provides this 2066C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1846constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2067C<IO::AIO::MAP_HUGETLB>,
1847C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2068C<IO::AIO::MAP_LOCKED>,
2069C<IO::AIO::MAP_NORESERVE>,
2070C<IO::AIO::MAP_POPULATE>,
1848C<IO::AIO::MAP_NONBLOCK> 2071C<IO::AIO::MAP_NONBLOCK>,
2072C<IO::AIO::MAP_FIXED>,
2073C<IO::AIO::MAP_GROWSDOWN>,
2074C<IO::AIO::MAP_32BIT>,
2075C<IO::AIO::MAP_HUGETLB> or
2076C<IO::AIO::MAP_STACK>.
1849 2077
1850If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2078If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1851 2079
1852C<$offset> is the offset from the start of the file - it generally must be 2080C<$offset> is the offset from the start of the file - it generally must be
1853a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2081a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1878 2106
1879Calls the C<munlockall> function. 2107Calls the C<munlockall> function.
1880 2108
1881On systems that do not implement C<munlockall>, this function returns 2109On systems that do not implement C<munlockall>, this function returns
1882ENOSYS, otherwise the return value of C<munlockall>. 2110ENOSYS, otherwise the return value of C<munlockall>.
2111
2112=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2113
2114Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2115C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
2116should be the file offset.
2117
2118C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2119silently corrupt the data in this case.
2120
2121The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
2122C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
2123C<IO::AIO::SPLICE_F_GIFT>.
2124
2125See the C<splice(2)> manpage for details.
2126
2127=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2128
2129Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2130description for C<IO::AIO::splice> above for details.
2131
2132=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2133
2134Attempts to query or change the pipe buffer size. Obviously works only
2135on pipes, and currently works only on GNU/Linux systems, and fails with
2136C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2137size on other systems, drop me a note.
2138
2139=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2140
2141This is a direct interface to the Linux L<pipe2(2)> system call. If
2142C<$flags> is missing or C<0>, then this should be the same as a call to
2143perl's built-in C<pipe> function and create a new pipe, and works on
2144systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2145(..., 4096, O_BINARY)>.
2146
2147If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2148the given flags (Linux 2.6.27, glibc 2.9).
2149
2150On success, the read and write file handles are returned.
2151
2152On error, nothing will be returned. If the pipe2 syscall is missing and
2153C<$flags> is non-zero, fails with C<ENOSYS>.
2154
2155Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2156time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2157C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
1883 2158
1884=back 2159=back
1885 2160
1886=cut 2161=cut
1887 2162

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