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Revision 1.57 by root, Mon Jan 18 11:53:09 2016 UTC vs.
Revision 1.60 by root, Tue Jul 31 22:27:49 2018 UTC

1NAME 1NAME
2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous/Advanced Input/Output
3 3
4SYNOPSIS 4SYNOPSIS
5 use IO::AIO; 5 use IO::AIO;
6 6
7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
… …
54 functions available on many operating systems. However, they are often 54 functions available on many operating systems. However, they are often
55 not well-supported or restricted (GNU/Linux doesn't allow them on normal 55 not well-supported or restricted (GNU/Linux doesn't allow them on normal
56 files currently, for example), and they would only support aio_read and 56 files currently, for example), and they would only support aio_read and
57 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
58 using threads anyway. 58 using threads anyway.
59
60 In addition to asynchronous I/O, this module also exports some rather
61 arcane interfaces, such as "madvise" or linux's "splice" system call,
62 which is why the "A" in "AIO" can also mean *advanced*.
59 63
60 Although the module will work in the presence of other (Perl-) threads, 64 Although the module will work in the presence of other (Perl-) threads,
61 it is currently not reentrant in any way, so use appropriate locking 65 it is currently not reentrant in any way, so use appropriate locking
62 yourself, always call "poll_cb" from within the same thread, or never 66 yourself, always call "poll_cb" from within the same thread, or never
63 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
… …
173 aio_link $srcpath, $dstpath, $callback->($status) 177 aio_link $srcpath, $dstpath, $callback->($status)
174 aio_symlink $srcpath, $dstpath, $callback->($status) 178 aio_symlink $srcpath, $dstpath, $callback->($status)
175 aio_readlink $pathname, $callback->($link) 179 aio_readlink $pathname, $callback->($link)
176 aio_realpath $pathname, $callback->($path) 180 aio_realpath $pathname, $callback->($path)
177 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
178 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
179 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
180 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
181 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
182 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
… …
184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
185 aio_load $pathname, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
186 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
187 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
188 aio_rmtree $pathname, $callback->($status) 193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
189 aio_sync $callback->($status) 196 aio_sync $callback->($status)
190 aio_syncfs $fh, $callback->($status) 197 aio_syncfs $fh, $callback->($status)
191 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
192 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
193 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
194 aio_pathsync $pathname, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
195 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
196 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
197 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
198 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
199 aio_group $callback->(...) 206 aio_group $callback->(...)
200 aio_nop $callback->() 207 aio_nop $callback->()
… …
214 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
215 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
216 IO::AIO::nreqs 223 IO::AIO::nreqs
217 IO::AIO::nready 224 IO::AIO::nready
218 IO::AIO::npending 225 IO::AIO::npending
226 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
227 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
219 228
220 IO::AIO::sendfile $ofh, $ifh, $offset, $count 229 IO::AIO::sendfile $ofh, $ifh, $offset, $count
221 IO::AIO::fadvise $fh, $offset, $len, $advice 230 IO::AIO::fadvise $fh, $offset, $len, $advice
222 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 231 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
223 IO::AIO::munmap $scalar 232 IO::AIO::munmap $scalar
233 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
224 IO::AIO::madvise $scalar, $offset, $length, $advice 234 IO::AIO::madvise $scalar, $offset, $length, $advice
225 IO::AIO::mprotect $scalar, $offset, $length, $protect 235 IO::AIO::mprotect $scalar, $offset, $length, $protect
226 IO::AIO::munlock $scalar, $offset = 0, $length = undef 236 IO::AIO::munlock $scalar, $offset = 0, $length = undef
227 IO::AIO::munlockall 237 IO::AIO::munlockall
228 238
… …
330 "O_APPEND"), the following POSIX and non-POSIX constants are 340 "O_APPEND"), the following POSIX and non-POSIX constants are
331 available (missing ones on your system are, as usual, 0): 341 available (missing ones on your system are, as usual, 0):
332 342
333 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 343 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
334 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 344 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
335 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and 345 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
336 "O_TTY_INIT". 346 and "O_ACCMODE".
337 347
338 aio_close $fh, $callback->($status) 348 aio_close $fh, $callback->($status)
339 Asynchronously close a file and call the callback with the result 349 Asynchronously close a file and call the callback with the result
340 code. 350 code.
341 351
… …
371 381
372 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
374 Reads or writes $length bytes from or to the specified $fh and 384 Reads or writes $length bytes from or to the specified $fh and
375 $offset into the scalar given by $data and offset $dataoffset and 385 $offset into the scalar given by $data and offset $dataoffset and
376 calls the callback without the actual number of bytes read (or -1 on 386 calls the callback with the actual number of bytes transferred (or
377 error, just like the syscall). 387 -1 on error, just like the syscall).
378 388
379 "aio_read" will, like "sysread", shrink or grow the $data scalar to 389 "aio_read" will, like "sysread", shrink or grow the $data scalar to
380 offset plus the actual number of bytes read. 390 offset plus the actual number of bytes read.
381 391
382 If $offset is undefined, then the current file descriptor offset 392 If $offset is undefined, then the current file descriptor offset
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439 As native sendfile syscalls (as practically any non-POSIX interface 449 As native sendfile syscalls (as practically any non-POSIX interface
440 hacked together in a hurry to improve benchmark numbers) tend to be 450 hacked together in a hurry to improve benchmark numbers) tend to be
441 rather buggy on many systems, this implementation tries to work 451 rather buggy on many systems, this implementation tries to work
442 around some known bugs in Linux and FreeBSD kernels (probably 452 around some known bugs in Linux and FreeBSD kernels (probably
443 others, too), but that might fail, so you really really should check 453 others, too), but that might fail, so you really really should check
444 the return value of "aio_sendfile" - fewre bytes than expected might 454 the return value of "aio_sendfile" - fewer bytes than expected might
445 have been transferred. 455 have been transferred.
446 456
447 aio_readahead $fh,$offset,$length, $callback->($retval) 457 aio_readahead $fh,$offset,$length, $callback->($retval)
448 "aio_readahead" populates the page cache with data from a file so 458 "aio_readahead" populates the page cache with data from a file so
449 that subsequent reads from that file will not block on disk I/O. The 459 that subsequent reads from that file will not block on disk I/O. The
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453 to a page boundary and bytes are read up to the next page boundary 463 to a page boundary and bytes are read up to the next page boundary
454 greater than or equal to (off-set+length). "aio_readahead" does not 464 greater than or equal to (off-set+length). "aio_readahead" does not
455 read beyond the end of the file. The current file offset of the file 465 read beyond the end of the file. The current file offset of the file
456 is left unchanged. 466 is left unchanged.
457 467
458 If that syscall doesn't exist (likely if your OS isn't Linux) it 468 If that syscall doesn't exist (likely if your kernel isn't Linux) it
459 will be emulated by simply reading the data, which would have a 469 will be emulated by simply reading the data, which would have a
460 similar effect. 470 similar effect.
461 471
462 aio_stat $fh_or_path, $callback->($status) 472 aio_stat $fh_or_path, $callback->($status)
463 aio_lstat $fh, $callback->($status) 473 aio_lstat $fh, $callback->($status)
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530 namemax => 255, 540 namemax => 255,
531 frsize => 1024, 541 frsize => 1024,
532 fsid => 1810 542 fsid => 1810
533 } 543 }
534 544
535 Here is a (likely partial - send me updates!) list of fsid values
536 used by Linux - it is safe to hardcode these when $^O is "linux":
537
538 0x0000adf5 adfs
539 0x0000adff affs
540 0x5346414f afs
541 0x09041934 anon-inode filesystem
542 0x00000187 autofs
543 0x42465331 befs
544 0x1badface bfs
545 0x42494e4d binfmt_misc
546 0x9123683e btrfs
547 0x0027e0eb cgroupfs
548 0xff534d42 cifs
549 0x73757245 coda
550 0x012ff7b7 coh
551 0x28cd3d45 cramfs
552 0x453dcd28 cramfs-wend (wrong endianness)
553 0x64626720 debugfs
554 0x00001373 devfs
555 0x00001cd1 devpts
556 0x0000f15f ecryptfs
557 0x00414a53 efs
558 0x0000137d ext
559 0x0000ef53 ext2/ext3/ext4
560 0x0000ef51 ext2
561 0xf2f52010 f2fs
562 0x00004006 fat
563 0x65735546 fuseblk
564 0x65735543 fusectl
565 0x0bad1dea futexfs
566 0x01161970 gfs2
567 0x47504653 gpfs
568 0x00004244 hfs
569 0xf995e849 hpfs
570 0x00c0ffee hostfs
571 0x958458f6 hugetlbfs
572 0x2bad1dea inotifyfs
573 0x00009660 isofs
574 0x000072b6 jffs2
575 0x3153464a jfs
576 0x6b414653 k-afs
577 0x0bd00bd0 lustre
578 0x0000137f minix
579 0x0000138f minix 30 char names
580 0x00002468 minix v2
581 0x00002478 minix v2 30 char names
582 0x00004d5a minix v3
583 0x19800202 mqueue
584 0x00004d44 msdos
585 0x0000564c novell
586 0x00006969 nfs
587 0x6e667364 nfsd
588 0x00003434 nilfs
589 0x5346544e ntfs
590 0x00009fa1 openprom
591 0x7461636F ocfs2
592 0x00009fa0 proc
593 0x6165676c pstorefs
594 0x0000002f qnx4
595 0x68191122 qnx6
596 0x858458f6 ramfs
597 0x52654973 reiserfs
598 0x00007275 romfs
599 0x67596969 rpc_pipefs
600 0x73636673 securityfs
601 0xf97cff8c selinux
602 0x0000517b smb
603 0x534f434b sockfs
604 0x73717368 squashfs
605 0x62656572 sysfs
606 0x012ff7b6 sysv2
607 0x012ff7b5 sysv4
608 0x01021994 tmpfs
609 0x15013346 udf
610 0x00011954 ufs
611 0x54190100 ufs byteswapped
612 0x00009fa2 usbdevfs
613 0x01021997 v9fs
614 0xa501fcf5 vxfs
615 0xabba1974 xenfs
616 0x012ff7b4 xenix
617 0x58465342 xfs
618 0x012fd16d xia
619
620 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 545 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
621 Works like perl's "utime" function (including the special case of 546 Works like perl's "utime" function (including the special case of
622 $atime and $mtime being undef). Fractional times are supported if 547 $atime and $mtime being undef). Fractional times are supported if
623 the underlying syscalls support them. 548 the underlying syscalls support them.
624 549
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655 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate 580 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
656 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 581 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
657 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 582 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
658 583
659 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range 584 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
660 (without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range 585 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
586 "FALLOC_FL_INSERT_RANGE" to insert a range and
587 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
661 (see your fallocate(2) manpage). 588 fallocate(2) manpage).
662 589
663 The file system block size used by "fallocate" is presumably the 590 The file system block size used by "fallocate" is presumably the
664 "f_bsize" returned by "statvfs". 591 "f_bsize" returned by "statvfs", but different filesystems and
592 filetypes can dictate other limitations.
665 593
666 If "fallocate" isn't available or cannot be emulated (currently no 594 If "fallocate" isn't available or cannot be emulated (currently no
667 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 595 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
668 596
669 aio_chmod $fh_or_path, $mode, $callback->($status) 597 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
713 641
714 On systems that support the AIO::WD working directory abstraction 642 On systems that support the AIO::WD working directory abstraction
715 natively, the case "[$wd, "."]" as $srcpath is specialcased - 643 natively, the case "[$wd, "."]" as $srcpath is specialcased -
716 instead of failing, "rename" is called on the absolute path of $wd. 644 instead of failing, "rename" is called on the absolute path of $wd.
717 645
646 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
647 Basically a version of "aio_rename" with an additional $flags
648 argument. Calling this with "$flags=0" is the same as calling
649 "aio_rename".
650
651 Non-zero flags are currently only supported on GNU/Linux systems
652 that support renameat2. Other systems fail with "ENOSYS" in this
653 case.
654
655 The following constants are available (missing ones are, as usual
656 0), see renameat2(2) for details:
657
658 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
659 "IO::AIO::RENAME_WHITEOUT".
660
718 aio_mkdir $pathname, $mode, $callback->($status) 661 aio_mkdir $pathname, $mode, $callback->($status)
719 Asynchronously mkdir (create) a directory and call the callback with 662 Asynchronously mkdir (create) a directory and call the callback with
720 the result code. $mode will be modified by the umask at the time the 663 the result code. $mode will be modified by the umask at the time the
721 request is executed, so do not change your umask. 664 request is executed, so do not change your umask.
722 665
… …
744 The flags are a combination of the following constants, ORed 687 The flags are a combination of the following constants, ORed
745 together (the flags will also be passed to the callback, possibly 688 together (the flags will also be passed to the callback, possibly
746 modified): 689 modified):
747 690
748 IO::AIO::READDIR_DENTS 691 IO::AIO::READDIR_DENTS
749 When this flag is off, then the callback gets an arrayref 692 Normally the callback gets an arrayref consisting of names only
750 consisting of names only (as with "aio_readdir"), otherwise it 693 (as with "aio_readdir"). If this flag is set, then the callback
751 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 694 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
752 describing a single directory entry in more detail. 695 describing a single directory entry in more detail:
753 696
754 $name is the name of the entry. 697 $name is the name of the entry.
755 698
756 $type is one of the "IO::AIO::DT_xxx" constants: 699 $type is one of the "IO::AIO::DT_xxx" constants:
757 700
758 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 701 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
759 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 702 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
760 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 703 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
761 704
762 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 705 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
763 you need to know, you have to run stat yourself. Also, for speed 706 you need to know, you have to run stat yourself. Also, for
764 reasons, the $type scalars are read-only: you can not modify 707 speed/memory reasons, the $type scalars are read-only: you must
765 them. 708 not modify them.
766 709
767 $inode is the inode number (which might not be exact on systems 710 $inode is the inode number (which might not be exact on systems
768 with 64 bit inode numbers and 32 bit perls). This field has 711 with 64 bit inode numbers and 32 bit perls). This field has
769 unspecified content on systems that do not deliver the inode 712 unspecified content on systems that do not deliver the inode
770 information. 713 information.
… …
782 of which names with short names are tried first. 725 of which names with short names are tried first.
783 726
784 IO::AIO::READDIR_STAT_ORDER 727 IO::AIO::READDIR_STAT_ORDER
785 When this flag is set, then the names will be returned in an 728 When this flag is set, then the names will be returned in an
786 order suitable for stat()'ing each one. That is, when you plan 729 order suitable for stat()'ing each one. That is, when you plan
787 to stat() all files in the given directory, then the returned 730 to stat() most or all files in the given directory, then the
788 order will likely be fastest. 731 returned order will likely be faster.
789 732
790 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 733 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
791 specified, then the likely dirs come first, resulting in a less 734 specified, then the likely dirs come first, resulting in a less
792 optimal stat order. 735 optimal stat order for stat'ing all entries, but likely a more
736 optimal order for finding subdirectories.
793 737
794 IO::AIO::READDIR_FOUND_UNKNOWN 738 IO::AIO::READDIR_FOUND_UNKNOWN
795 This flag should not be set when calling "aio_readdirx". 739 This flag should not be set when calling "aio_readdirx".
796 Instead, it is being set by "aio_readdirx", when any of the 740 Instead, it is being set by "aio_readdirx", when any of the
797 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this 741 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
798 flag therefore indicates that all $type's are known, which can 742 flag therefore indicates that all $type's are known, which can
799 be used to speed up some algorithms. 743 be used to speed up some algorithms.
800 744
745 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
746 Opens, reads and closes the given file. The data is put into $data,
747 which is resized as required.
748
749 If $offset is negative, then it is counted from the end of the file.
750
751 If $length is zero, then the remaining length of the file is used.
752 Also, in this case, the same limitations to modifying $data apply as
753 when IO::AIO::mmap is used, i.e. it must only be modified in-place
754 with "substr". If the size of the file is known, specifying a
755 non-zero $length results in a performance advantage.
756
757 This request is similar to the older "aio_load" request, but since
758 it is a single request, it might be more efficient to use.
759
760 Example: load /etc/passwd into $passwd.
761
762 my $passwd;
763 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
764 $_[0] >= 0
765 or die "/etc/passwd: $!\n";
766
767 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
768 print $passwd;
769 };
770 IO::AIO::flush;
771
801 aio_load $pathname, $data, $callback->($status) 772 aio_load $pathname, $data, $callback->($status)
802 This is a composite request that tries to fully load the given file 773 This is a composite request that tries to fully load the given file
803 into memory. Status is the same as with aio_read. 774 into memory. Status is the same as with aio_read.
775
776 Using "aio_slurp" might be more efficient, as it is a single
777 request.
804 778
805 aio_copy $srcpath, $dstpath, $callback->($status) 779 aio_copy $srcpath, $dstpath, $callback->($status)
806 Try to copy the *file* (directories not supported as either source 780 Try to copy the *file* (directories not supported as either source
807 or destination) from $srcpath to $dstpath and call the callback with 781 or destination) from $srcpath to $dstpath and call the callback with
808 a status of 0 (ok) or -1 (error, see $!). 782 a status of 0 (ok) or -1 (error, see $!).
783
784 Existing destination files will be truncated.
809 785
810 This is a composite request that creates the destination file with 786 This is a composite request that creates the destination file with
811 mode 0200 and copies the contents of the source file into it using 787 mode 0200 and copies the contents of the source file into it using
812 "aio_sendfile", followed by restoring atime, mtime, access mode and 788 "aio_sendfile", followed by restoring atime, mtime, access mode and
813 uid/gid, in that order. 789 uid/gid, in that order.
… …
830 to efficiently separate the entries of directory $path into two sets 806 to efficiently separate the entries of directory $path into two sets
831 of names, directories you can recurse into (directories), and ones 807 of names, directories you can recurse into (directories), and ones
832 you cannot recurse into (everything else, including symlinks to 808 you cannot recurse into (everything else, including symlinks to
833 directories). 809 directories).
834 810
835 "aio_scandir" is a composite request that creates of many sub 811 "aio_scandir" is a composite request that generates many sub
836 requests_ $maxreq specifies the maximum number of outstanding aio 812 requests. $maxreq specifies the maximum number of outstanding aio
837 requests that this function generates. If it is "<= 0", then a 813 requests that this function generates. If it is "<= 0", then a
838 suitable default will be chosen (currently 4). 814 suitable default will be chosen (currently 4).
839 815
840 On error, the callback is called without arguments, otherwise it 816 On error, the callback is called without arguments, otherwise it
841 receives two array-refs with path-relative entry names. 817 receives two array-refs with path-relative entry names.
… …
888 Delete a directory tree starting (and including) $path, return the 864 Delete a directory tree starting (and including) $path, return the
889 status of the final "rmdir" only. This is a composite request that 865 status of the final "rmdir" only. This is a composite request that
890 uses "aio_scandir" to recurse into and rmdir directories, and unlink 866 uses "aio_scandir" to recurse into and rmdir directories, and unlink
891 everything else. 867 everything else.
892 868
869 aio_fcntl $fh, $cmd, $arg, $callback->($status)
870 aio_ioctl $fh, $request, $buf, $callback->($status)
871 These work just like the "fcntl" and "ioctl" built-in functions,
872 except they execute asynchronously and pass the return value to the
873 callback.
874
875 Both calls can be used for a lot of things, some of which make more
876 sense to run asynchronously in their own thread, while some others
877 make less sense. For example, calls that block waiting for external
878 events, such as locking, will also lock down an I/O thread while it
879 is waiting, which can deadlock the whole I/O system. At the same
880 time, there might be no alternative to using a thread to wait.
881
882 So in general, you should only use these calls for things that do
883 (filesystem) I/O, not for things that wait for other events
884 (network, other processes), although if you are careful and know
885 what you are doing, you still can.
886
887 The following constants are available (missing ones are, as usual
888 0):
889
890 "F_DUPFD_CLOEXEC",
891
892 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
893
894 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
895 "FIDEDUPERANGE".
896
897 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
898 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
899
900 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
901 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
902 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
903
904 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
905 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
906 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
907 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
908 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
909
910 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
911 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
912 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
913 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
914 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
915 "FS_XFLAG_HASATTR",
916
893 aio_sync $callback->($status) 917 aio_sync $callback->($status)
894 Asynchronously call sync and call the callback when finished. 918 Asynchronously call sync and call the callback when finished.
895 919
896 aio_fsync $fh, $callback->($status) 920 aio_fsync $fh, $callback->($status)
897 Asynchronously call fsync on the given filehandle and call the 921 Asynchronously call fsync on the given filehandle and call the
… …
933 Future versions of this function might fall back to other methods 957 Future versions of this function might fall back to other methods
934 when "fsync" on the directory fails (such as calling "sync"). 958 when "fsync" on the directory fails (such as calling "sync").
935 959
936 Passes 0 when everything went ok, and -1 on error. 960 Passes 0 when everything went ok, and -1 on error.
937 961
938 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 962 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
939 $callback->($status) 963 $callback->($status)
940 This is a rather advanced IO::AIO call, which only works on 964 This is a rather advanced IO::AIO call, which only works on
941 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 965 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
942 also works on data scalars managed by the Sys::Mmap or Mmap modules, 966 also works on data scalars managed by the Sys::Mmap or Mmap modules,
943 note that the scalar must only be modified in-place while an aio 967 note that the scalar must only be modified in-place while an aio
… …
945 969
946 It calls the "msync" function of your OS, if available, with the 970 It calls the "msync" function of your OS, if available, with the
947 memory area starting at $offset in the string and ending $length 971 memory area starting at $offset in the string and ending $length
948 bytes later. If $length is negative, counts from the end, and if 972 bytes later. If $length is negative, counts from the end, and if
949 $length is "undef", then it goes till the end of the string. The 973 $length is "undef", then it goes till the end of the string. The
950 flags can be a combination of "IO::AIO::MS_ASYNC", 974 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
951 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 975 an optional "IO::AIO::MS_INVALIDATE".
952 976
953 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 977 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
954 $callback->($status) 978 $callback->($status)
955 This is a rather advanced IO::AIO call, which works best on 979 This is a rather advanced IO::AIO call, which works best on
956 mmap(2)ed scalars. 980 mmap(2)ed scalars.
… …
1042 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1066 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1043 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1067 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1044 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1068 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1045 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1069 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1046 1070
1047 At the time of this writing (Linux 3.2), this requets is unreliable 1071 At the time of this writing (Linux 3.2), this request is unreliable
1048 unless $count is "undef", as the kernel has all sorts of bugs 1072 unless $count is "undef", as the kernel has all sorts of bugs
1049 preventing it to return all extents of a range for files with large 1073 preventing it to return all extents of a range for files with a
1050 number of extents. The code works around all these issues if $count 1074 large number of extents. The code (only) works around all these
1051 is undef. 1075 issues if $count is "undef".
1052 1076
1053 aio_group $callback->(...) 1077 aio_group $callback->(...)
1054 This is a very special aio request: Instead of doing something, it 1078 This is a very special aio request: Instead of doing something, it
1055 is a container for other aio requests, which is useful if you want 1079 is a container for other aio requests, which is useful if you want
1056 to bundle many requests into a single, composite, request with a 1080 to bundle many requests into a single, composite, request with a
… …
1165 There are some caveats: when directories get renamed (or deleted), the 1189 There are some caveats: when directories get renamed (or deleted), the
1166 pathname string doesn't change, so will point to the new directory (or 1190 pathname string doesn't change, so will point to the new directory (or
1167 nowhere at all), while the directory fd, if available on the system, 1191 nowhere at all), while the directory fd, if available on the system,
1168 will still point to the original directory. Most functions accepting a 1192 will still point to the original directory. Most functions accepting a
1169 pathname will use the directory fd on newer systems, and the string on 1193 pathname will use the directory fd on newer systems, and the string on
1170 older systems. Some functions (such as realpath) will always rely on the 1194 older systems. Some functions (such as "aio_realpath") will always rely
1171 string form of the pathname. 1195 on the string form of the pathname.
1172 1196
1173 So this functionality is mainly useful to get some protection against 1197 So this functionality is mainly useful to get some protection against
1174 "chdir", to easily get an absolute path out of a relative path for 1198 "chdir", to easily get an absolute path out of a relative path for
1175 future reference, and to speed up doing many operations in the same 1199 future reference, and to speed up doing many operations in the same
1176 directory (e.g. when stat'ing all files in a directory). 1200 directory (e.g. when stat'ing all files in a directory).
… …
1527 This is a very bad function to use in interactive programs because 1551 This is a very bad function to use in interactive programs because
1528 it blocks, and a bad way to reduce concurrency because it is 1552 it blocks, and a bad way to reduce concurrency because it is
1529 inexact: Better use an "aio_group" together with a feed callback. 1553 inexact: Better use an "aio_group" together with a feed callback.
1530 1554
1531 Its main use is in scripts without an event loop - when you want to 1555 Its main use is in scripts without an event loop - when you want to
1532 stat a lot of files, you can write somehting like this: 1556 stat a lot of files, you can write something like this:
1533 1557
1534 IO::AIO::max_outstanding 32; 1558 IO::AIO::max_outstanding 32;
1535 1559
1536 for my $path (...) { 1560 for my $path (...) {
1537 aio_stat $path , ...; 1561 aio_stat $path , ...;
… …
1571 MISCELLANEOUS FUNCTIONS 1595 MISCELLANEOUS FUNCTIONS
1572 IO::AIO implements some functions that are useful when you want to use 1596 IO::AIO implements some functions that are useful when you want to use
1573 some "Advanced I/O" function not available to in Perl, without going the 1597 some "Advanced I/O" function not available to in Perl, without going the
1574 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*" 1598 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1575 counterpart. 1599 counterpart.
1600
1601 $numfd = IO::AIO::get_fdlimit
1602 This function is *EXPERIMENTAL* and subject to change.
1603
1604 Tries to find the current file descriptor limit and returns it, or
1605 "undef" and sets $! in case of an error. The limit is one larger
1606 than the highest valid file descriptor number.
1607
1608 IO::AIO::min_fdlimit [$numfd]
1609 This function is *EXPERIMENTAL* and subject to change.
1610
1611 Try to increase the current file descriptor limit(s) to at least
1612 $numfd by changing the soft or hard file descriptor resource limit.
1613 If $numfd is missing, it will try to set a very high limit, although
1614 this is not recommended when you know the actual minimum that you
1615 require.
1616
1617 If the limit cannot be raised enough, the function makes a
1618 best-effort attempt to increase the limit as much as possible, using
1619 various tricks, while still failing. You can query the resulting
1620 limit using "IO::AIO::get_fdlimit".
1621
1622 If an error occurs, returns "undef" and sets $!, otherwise returns
1623 true.
1576 1624
1577 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1625 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1578 Calls the "eio_sendfile_sync" function, which is like 1626 Calls the "eio_sendfile_sync" function, which is like
1579 "aio_sendfile", but is blocking (this makes most sense if you know 1627 "aio_sendfile", but is blocking (this makes most sense if you know
1580 the input data is likely cached already and the output filehandle is 1628 the input data is likely cached already and the output filehandle is
… …
1597 details). The following advice constants are available: 1645 details). The following advice constants are available:
1598 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1646 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1599 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1647 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1600 "IO::AIO::MADV_DONTNEED". 1648 "IO::AIO::MADV_DONTNEED".
1601 1649
1650 If $offset is negative, counts from the end. If $length is negative,
1651 the remaining length of the $scalar is used. If possible, $length
1652 will be reduced to fit into the $scalar.
1653
1602 On systems that do not implement "posix_madvise", this function 1654 On systems that do not implement "posix_madvise", this function
1603 returns ENOSYS, otherwise the return value of "posix_madvise". 1655 returns ENOSYS, otherwise the return value of "posix_madvise".
1604 1656
1605 IO::AIO::mprotect $scalar, $offset, $len, $protect 1657 IO::AIO::mprotect $scalar, $offset, $len, $protect
1606 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1658 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1607 $scalar (see its manpage for details). The following protect 1659 $scalar (see its manpage for details). The following protect
1608 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1660 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1609 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1661 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1610 1662
1663 If $offset is negative, counts from the end. If $length is negative,
1664 the remaining length of the $scalar is used. If possible, $length
1665 will be reduced to fit into the $scalar.
1666
1611 On systems that do not implement "mprotect", this function returns 1667 On systems that do not implement "mprotect", this function returns
1612 ENOSYS, otherwise the return value of "mprotect". 1668 ENOSYS, otherwise the return value of "mprotect".
1613 1669
1614 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1670 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1615 Memory-maps a file (or anonymous memory range) and attaches it to 1671 Memory-maps a file (or anonymous memory range) and attaches it to
1616 the given $scalar, which will act like a string scalar. Returns true 1672 the given $scalar, which will act like a string scalar. Returns true
1617 on success, and false otherwise. 1673 on success, and false otherwise.
1618 1674
1675 The scalar must exist, but its contents do not matter - this means
1676 you cannot use a nonexistant array or hash element. When in doubt,
1677 "undef" the scalar first.
1678
1619 The only operations allowed on the scalar are "substr"/"vec" that 1679 The only operations allowed on the mmapped scalar are
1620 don't change the string length, and most read-only operations such 1680 "substr"/"vec", which don't change the string length, and most
1621 as copying it or searching it with regexes and so on. 1681 read-only operations such as copying it or searching it with regexes
1682 and so on.
1622 1683
1623 Anything else is unsafe and will, at best, result in memory leaks. 1684 Anything else is unsafe and will, at best, result in memory leaks.
1624 1685
1625 The memory map associated with the $scalar is automatically removed 1686 The memory map associated with the $scalar is automatically removed
1626 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1687 when the $scalar is undef'd or destroyed, or when the
1627 "IO::AIO::munmap" functions are called. 1688 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1628 1689
1629 This calls the "mmap"(2) function internally. See your system's 1690 This calls the "mmap"(2) function internally. See your system's
1630 manual page for details on the $length, $prot and $flags parameters. 1691 manual page for details on the $length, $prot and $flags parameters.
1631 1692
1632 The $length must be larger than zero and smaller than the actual 1693 The $length must be larger than zero and smaller than the actual
… …
1638 1699
1639 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1700 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1640 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1701 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1641 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to 1702 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1642 "MAP_ANON" if your system only provides this constant), 1703 "MAP_ANON" if your system only provides this constant),
1704 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1643 "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1705 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1644 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE", 1706 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1645 "IO::AIO::MAP_NONBLOCK", "IO::AIO::MAP_FIXED", 1707 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1646 "IO::AIO::MAP_GROWSDOWN", "IO::AIO::MAP_32BIT", 1708 "IO::AIO::MAP_STACK".
1647 "IO::AIO::MAP_HUGETLB" or "IO::AIO::MAP_STACK".
1648 1709
1649 If $fh is "undef", then a file descriptor of -1 is passed. 1710 If $fh is "undef", then a file descriptor of -1 is passed.
1650 1711
1651 $offset is the offset from the start of the file - it generally must 1712 $offset is the offset from the start of the file - it generally must
1652 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1713 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1664 1725
1665 my $fast_md5 = md5 $data; 1726 my $fast_md5 = md5 $data;
1666 1727
1667 IO::AIO::munmap $scalar 1728 IO::AIO::munmap $scalar
1668 Removes a previous mmap and undefines the $scalar. 1729 Removes a previous mmap and undefines the $scalar.
1730
1731 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1732 $new_address = 0]
1733 Calls the Linux-specific mremap(2) system call. The $scalar must
1734 have been mapped by "IO::AIO::mmap", and $flags must currently
1735 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1736
1737 Returns true if successful, and false otherwise. If the underlying
1738 mmapped region has changed address, then the true value has the
1739 numerical value 1, otherwise it has the numerical value 0:
1740
1741 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1742 or die "mremap: $!";
1743
1744 if ($success*1) {
1745 warn "scalar has chanegd address in memory\n";
1746 }
1747
1748 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1749 implemented, but not supported and might go away in a future
1750 version.
1751
1752 On systems where this call is not supported or is not emulated, this
1753 call returns falls and sets $! to "ENOSYS".
1669 1754
1670 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1755 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1671 Calls the "munlock" function, undoing the effects of a previous 1756 Calls the "munlock" function, undoing the effects of a previous
1672 "aio_mlock" call (see its description for details). 1757 "aio_mlock" call (see its description for details).
1673 1758
… …
1718 1803
1719 Please refer to pipe2(2) for more info on the $flags, but at the 1804 Please refer to pipe2(2) for more info on the $flags, but at the
1720 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" 1805 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1721 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were 1806 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1722 supported. 1807 supported.
1808
1809 Example: create a pipe race-free w.r.t. threads and fork:
1810
1811 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1812 or die "pipe2: $!\n";
1813
1814 $fh = IO::AIO::eventfd [$initval, [$flags]]
1815 This is a direct interface to the Linux eventfd(2) system call. The
1816 (unhelpful) defaults for $initval and $flags are 0 for both.
1817
1818 On success, the new eventfd filehandle is returned, otherwise
1819 returns "undef". If the eventfd syscall is missing, fails with
1820 "ENOSYS".
1821
1822 Please refer to eventfd(2) for more info on this call.
1823
1824 The following symbol flag values are available:
1825 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1826 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1827
1828 Example: create a new eventfd filehandle:
1829
1830 $fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
1831 or die "eventfd: $!\n";
1832
1833 $fh = IO::AIO::timerfd_create $clockid[, $flags]
1834 This is a direct interface to the Linux timerfd_create(2) system
1835 call. The (unhelpful) default for $flags is 0.
1836
1837 On success, the new timerfd filehandle is returned, otherwise
1838 returns "undef". If the eventfd syscall is missing, fails with
1839 "ENOSYS".
1840
1841 Please refer to timerfd_create(2) for more info on this call.
1842
1843 The following $clockid values are available:
1844 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
1845 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
1846 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
1847 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
1848
1849 The following $flags values are available (Linux 2.6.27):
1850 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
1851
1852 Example: create a new timerfd and set it to one-second repeated
1853 alarms, then wait for two alarms:
1854
1855 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
1856 or die "timerfd_create: $!\n";
1857
1858 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
1859 or die "timerfd_settime: $!\n";
1860
1861 for (1..2) {
1862 8 == sysread $fh, my $buf, 8
1863 or die "timerfd read failure\n";
1864
1865 printf "number of expirations (likely 1): %d\n",
1866 unpack "Q", $buf;
1867 }
1868
1869 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
1870 $new_interval, $nbw_value
1871 This is a direct interface to the Linux timerfd_settime(2) system
1872 call. Please refer to its manpage for more info on this call.
1873
1874 The new itimerspec is specified using two (possibly fractional)
1875 second values, $new_interval and $new_value).
1876
1877 On success, the current interval and value are returned (as per
1878 "timerfd_gettime"). On failure, the empty list is returned.
1879
1880 The following $flags values are available:
1881 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
1882
1883 See "IO::AIO::timerfd_create" for a full example.
1884
1885 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
1886 This is a direct interface to the Linux timerfd_gettime(2) system
1887 call. Please refer to its manpage for more info on this call.
1888
1889 On success, returns the current values of interval and value for the
1890 given timerfd (as potentially fractional second values). On failure,
1891 the empty list is returned.
1723 1892
1724EVENT LOOP INTEGRATION 1893EVENT LOOP INTEGRATION
1725 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1894 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1726 automatically into many event loops: 1895 automatically into many event loops:
1727 1896
… …
1777 forking, if "IO::AIO" was used in the parent. Calling it while 1946 forking, if "IO::AIO" was used in the parent. Calling it while
1778 IO::AIO is active in the process will result in undefined behaviour. 1947 IO::AIO is active in the process will result in undefined behaviour.
1779 Calling it at any time will also result in any undefined (by POSIX) 1948 Calling it at any time will also result in any undefined (by POSIX)
1780 behaviour. 1949 behaviour.
1781 1950
1951 LINUX-SPECIFIC CALLS
1952 When a call is documented as "linux-specific" then this means it
1953 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
1954 availability and compatibility of such calls regardless of the platform
1955 it is compiled on, so platforms such as FreeBSD which often implement
1956 these calls will work. When in doubt, call them and see if they fail wth
1957 "ENOSYS".
1958
1782 MEMORY USAGE 1959 MEMORY USAGE
1783 Per-request usage: 1960 Per-request usage:
1784 1961
1785 Each aio request uses - depending on your architecture - around 100-200 1962 Each aio request uses - depending on your architecture - around 100-200
1786 bytes of memory. In addition, stat requests need a stat buffer (possibly 1963 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1796 In the execution phase, some aio requests require more memory for 1973 In the execution phase, some aio requests require more memory for
1797 temporary buffers, and each thread requires a stack and other data 1974 temporary buffers, and each thread requires a stack and other data
1798 structures (usually around 16k-128k, depending on the OS). 1975 structures (usually around 16k-128k, depending on the OS).
1799 1976
1800KNOWN BUGS 1977KNOWN BUGS
1801 Known bugs will be fixed in the next release. 1978 Known bugs will be fixed in the next release :)
1979
1980KNOWN ISSUES
1981 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
1982 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
1983 non-created hash slots or other scalars I didn't think of. It's best to
1984 avoid such and either use scalar variables or making sure that the
1985 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
1986
1987 I am not sure anything can be done about this, so this is considered a
1988 known issue, rather than a bug.
1802 1989
1803SEE ALSO 1990SEE ALSO
1804 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 1991 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1805 more natural syntax. 1992 more natural syntax.
1806 1993

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