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Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC vs.
Revision 1.59 by root, Tue Feb 20 06:54:47 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.
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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
… …
192 aio_syncfs $fh, $callback->($status) 197 aio_syncfs $fh, $callback->($status)
193 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
194 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
195 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
196 aio_pathsync $pathname, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
197 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
198 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
199 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
200 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
201 aio_group $callback->(...) 206 aio_group $callback->(...)
202 aio_nop $callback->() 207 aio_nop $callback->()
… …
216 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
217 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
218 IO::AIO::nreqs 223 IO::AIO::nreqs
219 IO::AIO::nready 224 IO::AIO::nready
220 IO::AIO::npending 225 IO::AIO::npending
226 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
227 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
221 228
222 IO::AIO::sendfile $ofh, $ifh, $offset, $count 229 IO::AIO::sendfile $ofh, $ifh, $offset, $count
223 IO::AIO::fadvise $fh, $offset, $len, $advice 230 IO::AIO::fadvise $fh, $offset, $len, $advice
224 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 231 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
225 IO::AIO::munmap $scalar 232 IO::AIO::munmap $scalar
… …
373 380
374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 381 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
376 Reads or writes $length bytes from or to the specified $fh and 383 Reads or writes $length bytes from or to the specified $fh and
377 $offset into the scalar given by $data and offset $dataoffset and 384 $offset into the scalar given by $data and offset $dataoffset and
378 calls the callback without the actual number of bytes read (or -1 on 385 calls the callback with the actual number of bytes transferred (or
379 error, just like the syscall). 386 -1 on error, just like the syscall).
380 387
381 "aio_read" will, like "sysread", shrink or grow the $data scalar to 388 "aio_read" will, like "sysread", shrink or grow the $data scalar to
382 offset plus the actual number of bytes read. 389 offset plus the actual number of bytes read.
383 390
384 If $offset is undefined, then the current file descriptor offset 391 If $offset is undefined, then the current file descriptor offset
… …
441 As native sendfile syscalls (as practically any non-POSIX interface 448 As native sendfile syscalls (as practically any non-POSIX interface
442 hacked together in a hurry to improve benchmark numbers) tend to be 449 hacked together in a hurry to improve benchmark numbers) tend to be
443 rather buggy on many systems, this implementation tries to work 450 rather buggy on many systems, this implementation tries to work
444 around some known bugs in Linux and FreeBSD kernels (probably 451 around some known bugs in Linux and FreeBSD kernels (probably
445 others, too), but that might fail, so you really really should check 452 others, too), but that might fail, so you really really should check
446 the return value of "aio_sendfile" - fewre bytes than expected might 453 the return value of "aio_sendfile" - fewer bytes than expected might
447 have been transferred. 454 have been transferred.
448 455
449 aio_readahead $fh,$offset,$length, $callback->($retval) 456 aio_readahead $fh,$offset,$length, $callback->($retval)
450 "aio_readahead" populates the page cache with data from a file so 457 "aio_readahead" populates the page cache with data from a file so
451 that subsequent reads from that file will not block on disk I/O. The 458 that subsequent reads from that file will not block on disk I/O. The
… …
455 to a page boundary and bytes are read up to the next page boundary 462 to a page boundary and bytes are read up to the next page boundary
456 greater than or equal to (off-set+length). "aio_readahead" does not 463 greater than or equal to (off-set+length). "aio_readahead" does not
457 read beyond the end of the file. The current file offset of the file 464 read beyond the end of the file. The current file offset of the file
458 is left unchanged. 465 is left unchanged.
459 466
460 If that syscall doesn't exist (likely if your OS isn't Linux) it 467 If that syscall doesn't exist (likely if your kernel isn't Linux) it
461 will be emulated by simply reading the data, which would have a 468 will be emulated by simply reading the data, which would have a
462 similar effect. 469 similar effect.
463 470
464 aio_stat $fh_or_path, $callback->($status) 471 aio_stat $fh_or_path, $callback->($status)
465 aio_lstat $fh, $callback->($status) 472 aio_lstat $fh, $callback->($status)
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532 namemax => 255, 539 namemax => 255,
533 frsize => 1024, 540 frsize => 1024,
534 fsid => 1810 541 fsid => 1810
535 } 542 }
536 543
537 Here is a (likely partial - send me updates!) list of fsid values
538 used by Linux - it is safe to hardcode these when $^O is "linux":
539
540 0x0000adf5 adfs
541 0x0000adff affs
542 0x5346414f afs
543 0x09041934 anon-inode filesystem
544 0x00000187 autofs
545 0x42465331 befs
546 0x1badface bfs
547 0x42494e4d binfmt_misc
548 0x9123683e btrfs
549 0x0027e0eb cgroupfs
550 0xff534d42 cifs
551 0x73757245 coda
552 0x012ff7b7 coh
553 0x28cd3d45 cramfs
554 0x453dcd28 cramfs-wend (wrong endianness)
555 0x64626720 debugfs
556 0x00001373 devfs
557 0x00001cd1 devpts
558 0x0000f15f ecryptfs
559 0x00414a53 efs
560 0x0000137d ext
561 0x0000ef53 ext2/ext3/ext4
562 0x0000ef51 ext2
563 0xf2f52010 f2fs
564 0x00004006 fat
565 0x65735546 fuseblk
566 0x65735543 fusectl
567 0x0bad1dea futexfs
568 0x01161970 gfs2
569 0x47504653 gpfs
570 0x00004244 hfs
571 0xf995e849 hpfs
572 0x00c0ffee hostfs
573 0x958458f6 hugetlbfs
574 0x2bad1dea inotifyfs
575 0x00009660 isofs
576 0x000072b6 jffs2
577 0x3153464a jfs
578 0x6b414653 k-afs
579 0x0bd00bd0 lustre
580 0x0000137f minix
581 0x0000138f minix 30 char names
582 0x00002468 minix v2
583 0x00002478 minix v2 30 char names
584 0x00004d5a minix v3
585 0x19800202 mqueue
586 0x00004d44 msdos
587 0x0000564c novell
588 0x00006969 nfs
589 0x6e667364 nfsd
590 0x00003434 nilfs
591 0x5346544e ntfs
592 0x00009fa1 openprom
593 0x7461636F ocfs2
594 0x00009fa0 proc
595 0x6165676c pstorefs
596 0x0000002f qnx4
597 0x68191122 qnx6
598 0x858458f6 ramfs
599 0x52654973 reiserfs
600 0x00007275 romfs
601 0x67596969 rpc_pipefs
602 0x73636673 securityfs
603 0xf97cff8c selinux
604 0x0000517b smb
605 0x534f434b sockfs
606 0x73717368 squashfs
607 0x62656572 sysfs
608 0x012ff7b6 sysv2
609 0x012ff7b5 sysv4
610 0x01021994 tmpfs
611 0x15013346 udf
612 0x00011954 ufs
613 0x54190100 ufs byteswapped
614 0x00009fa2 usbdevfs
615 0x01021997 v9fs
616 0xa501fcf5 vxfs
617 0xabba1974 xenfs
618 0x012ff7b4 xenix
619 0x58465342 xfs
620 0x012fd16d xia
621
622 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 544 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
623 Works like perl's "utime" function (including the special case of 545 Works like perl's "utime" function (including the special case of
624 $atime and $mtime being undef). Fractional times are supported if 546 $atime and $mtime being undef). Fractional times are supported if
625 the underlying syscalls support them. 547 the underlying syscalls support them.
626 548
… …
657 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate 579 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
658 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 580 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
659 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 581 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
660 582
661 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range 583 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
662 (without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range 584 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
585 "FALLOC_FL_INSERT_RANGE" to insert a range and
586 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
663 (see your fallocate(2) manpage). 587 fallocate(2) manpage).
664 588
665 The file system block size used by "fallocate" is presumably the 589 The file system block size used by "fallocate" is presumably the
666 "f_bsize" returned by "statvfs". 590 "f_bsize" returned by "statvfs", but different filesystems and
591 filetypes can dictate other limitations.
667 592
668 If "fallocate" isn't available or cannot be emulated (currently no 593 If "fallocate" isn't available or cannot be emulated (currently no
669 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 594 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
670 595
671 aio_chmod $fh_or_path, $mode, $callback->($status) 596 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
714 rename(2) and call the callback with the result code. 639 rename(2) and call the callback with the result code.
715 640
716 On systems that support the AIO::WD working directory abstraction 641 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased - 642 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd. 643 instead of failing, "rename" is called on the absolute path of $wd.
644
645 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
646 Basically a version of "aio_rename" with an additional $flags
647 argument. Calling this with "$flags=0" is the same as calling
648 "aio_rename".
649
650 Non-zero flags are currently only supported on GNU/Linux systems
651 that support renameat2. Other systems fail with "ENOSYS" in this
652 case.
653
654 The following constants are available (missing ones are, as usual
655 0), see renameat2(2) for details:
656
657 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
658 "IO::AIO::RENAME_WHITEOUT".
719 659
720 aio_mkdir $pathname, $mode, $callback->($status) 660 aio_mkdir $pathname, $mode, $callback->($status)
721 Asynchronously mkdir (create) a directory and call the callback with 661 Asynchronously mkdir (create) a directory and call the callback with
722 the result code. $mode will be modified by the umask at the time the 662 the result code. $mode will be modified by the umask at the time the
723 request is executed, so do not change your umask. 663 request is executed, so do not change your umask.
… …
798 Instead, it is being set by "aio_readdirx", when any of the 738 Instead, it is being set by "aio_readdirx", when any of the
799 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this 739 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
800 flag therefore indicates that all $type's are known, which can 740 flag therefore indicates that all $type's are known, which can
801 be used to speed up some algorithms. 741 be used to speed up some algorithms.
802 742
743 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
744 Opens, reads and closes the given file. The data is put into $data,
745 which is resized as required.
746
747 If $offset is negative, then it is counted from the end of the file.
748
749 If $length is zero, then the remaining length of the file is used.
750 Also, in this case, the same limitations to modifying $data apply as
751 when IO::AIO::mmap is used, i.e. it must only be modified in-place
752 with "substr". If the size of the file is known, specifying a
753 non-zero $length results in a performance advantage.
754
755 This request is similar to the older "aio_load" request, but since
756 it is a single request, it might be more efficient to use.
757
758 Example: load /etc/passwd into $passwd.
759
760 my $passwd;
761 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
762 $_[0] >= 0
763 or die "/etc/passwd: $!\n";
764
765 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
766 print $passwd;
767 };
768 IO::AIO::flush;
769
803 aio_load $pathname, $data, $callback->($status) 770 aio_load $pathname, $data, $callback->($status)
804 This is a composite request that tries to fully load the given file 771 This is a composite request that tries to fully load the given file
805 into memory. Status is the same as with aio_read. 772 into memory. Status is the same as with aio_read.
773
774 Using "aio_slurp" might be more efficient, as it is a single
775 request.
806 776
807 aio_copy $srcpath, $dstpath, $callback->($status) 777 aio_copy $srcpath, $dstpath, $callback->($status)
808 Try to copy the *file* (directories not supported as either source 778 Try to copy the *file* (directories not supported as either source
809 or destination) from $srcpath to $dstpath and call the callback with 779 or destination) from $srcpath to $dstpath and call the callback with
810 a status of 0 (ok) or -1 (error, see $!). 780 a status of 0 (ok) or -1 (error, see $!).
781
782 Existing destination files will be truncated.
811 783
812 This is a composite request that creates the destination file with 784 This is a composite request that creates the destination file with
813 mode 0200 and copies the contents of the source file into it using 785 mode 0200 and copies the contents of the source file into it using
814 "aio_sendfile", followed by restoring atime, mtime, access mode and 786 "aio_sendfile", followed by restoring atime, mtime, access mode and
815 uid/gid, in that order. 787 uid/gid, in that order.
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832 to efficiently separate the entries of directory $path into two sets 804 to efficiently separate the entries of directory $path into two sets
833 of names, directories you can recurse into (directories), and ones 805 of names, directories you can recurse into (directories), and ones
834 you cannot recurse into (everything else, including symlinks to 806 you cannot recurse into (everything else, including symlinks to
835 directories). 807 directories).
836 808
837 "aio_scandir" is a composite request that creates of many sub 809 "aio_scandir" is a composite request that generates many sub
838 requests_ $maxreq specifies the maximum number of outstanding aio 810 requests. $maxreq specifies the maximum number of outstanding aio
839 requests that this function generates. If it is "<= 0", then a 811 requests that this function generates. If it is "<= 0", then a
840 suitable default will be chosen (currently 4). 812 suitable default will be chosen (currently 4).
841 813
842 On error, the callback is called without arguments, otherwise it 814 On error, the callback is called without arguments, otherwise it
843 receives two array-refs with path-relative entry names. 815 receives two array-refs with path-relative entry names.
… …
908 So in general, you should only use these calls for things that do 880 So in general, you should only use these calls for things that do
909 (filesystem) I/O, not for things that wait for other events 881 (filesystem) I/O, not for things that wait for other events
910 (network, other processes), although if you are careful and know 882 (network, other processes), although if you are careful and know
911 what you are doing, you still can. 883 what you are doing, you still can.
912 884
885 The following constants are available (missing ones are, as usual
886 0):
887
888 "F_DUPFD_CLOEXEC",
889
890 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
891
892 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
893 "FIDEDUPERANGE".
894
895 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
896 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
897
898 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
899 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
900 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
901
902 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
903 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
904 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
905 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
906 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
907
908 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
909 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
910 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
911 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
912 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
913 "FS_XFLAG_HASATTR",
914
913 aio_sync $callback->($status) 915 aio_sync $callback->($status)
914 Asynchronously call sync and call the callback when finished. 916 Asynchronously call sync and call the callback when finished.
915 917
916 aio_fsync $fh, $callback->($status) 918 aio_fsync $fh, $callback->($status)
917 Asynchronously call fsync on the given filehandle and call the 919 Asynchronously call fsync on the given filehandle and call the
… …
953 Future versions of this function might fall back to other methods 955 Future versions of this function might fall back to other methods
954 when "fsync" on the directory fails (such as calling "sync"). 956 when "fsync" on the directory fails (such as calling "sync").
955 957
956 Passes 0 when everything went ok, and -1 on error. 958 Passes 0 when everything went ok, and -1 on error.
957 959
958 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 960 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
959 $callback->($status) 961 $callback->($status)
960 This is a rather advanced IO::AIO call, which only works on 962 This is a rather advanced IO::AIO call, which only works on
961 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 963 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
962 also works on data scalars managed by the Sys::Mmap or Mmap modules, 964 also works on data scalars managed by the Sys::Mmap or Mmap modules,
963 note that the scalar must only be modified in-place while an aio 965 note that the scalar must only be modified in-place while an aio
… …
965 967
966 It calls the "msync" function of your OS, if available, with the 968 It calls the "msync" function of your OS, if available, with the
967 memory area starting at $offset in the string and ending $length 969 memory area starting at $offset in the string and ending $length
968 bytes later. If $length is negative, counts from the end, and if 970 bytes later. If $length is negative, counts from the end, and if
969 $length is "undef", then it goes till the end of the string. The 971 $length is "undef", then it goes till the end of the string. The
970 flags can be a combination of "IO::AIO::MS_ASYNC", 972 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
971 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 973 an optional "IO::AIO::MS_INVALIDATE".
972 974
973 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 975 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
974 $callback->($status) 976 $callback->($status)
975 This is a rather advanced IO::AIO call, which works best on 977 This is a rather advanced IO::AIO call, which works best on
976 mmap(2)ed scalars. 978 mmap(2)ed scalars.
… …
1062 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1064 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1063 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1065 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1064 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1066 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1065 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1067 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1066 1068
1067 At the time of this writing (Linux 3.2), this requets is unreliable 1069 At the time of this writing (Linux 3.2), this request is unreliable
1068 unless $count is "undef", as the kernel has all sorts of bugs 1070 unless $count is "undef", as the kernel has all sorts of bugs
1069 preventing it to return all extents of a range for files with large 1071 preventing it to return all extents of a range for files with a
1070 number of extents. The code works around all these issues if $count 1072 large number of extents. The code (only) works around all these
1071 is undef. 1073 issues if $count is "undef".
1072 1074
1073 aio_group $callback->(...) 1075 aio_group $callback->(...)
1074 This is a very special aio request: Instead of doing something, it 1076 This is a very special aio request: Instead of doing something, it
1075 is a container for other aio requests, which is useful if you want 1077 is a container for other aio requests, which is useful if you want
1076 to bundle many requests into a single, composite, request with a 1078 to bundle many requests into a single, composite, request with a
… …
1185 There are some caveats: when directories get renamed (or deleted), the 1187 There are some caveats: when directories get renamed (or deleted), the
1186 pathname string doesn't change, so will point to the new directory (or 1188 pathname string doesn't change, so will point to the new directory (or
1187 nowhere at all), while the directory fd, if available on the system, 1189 nowhere at all), while the directory fd, if available on the system,
1188 will still point to the original directory. Most functions accepting a 1190 will still point to the original directory. Most functions accepting a
1189 pathname will use the directory fd on newer systems, and the string on 1191 pathname will use the directory fd on newer systems, and the string on
1190 older systems. Some functions (such as realpath) will always rely on the 1192 older systems. Some functions (such as "aio_realpath") will always rely
1191 string form of the pathname. 1193 on the string form of the pathname.
1192 1194
1193 So this functionality is mainly useful to get some protection against 1195 So this functionality is mainly useful to get some protection against
1194 "chdir", to easily get an absolute path out of a relative path for 1196 "chdir", to easily get an absolute path out of a relative path for
1195 future reference, and to speed up doing many operations in the same 1197 future reference, and to speed up doing many operations in the same
1196 directory (e.g. when stat'ing all files in a directory). 1198 directory (e.g. when stat'ing all files in a directory).
… …
1547 This is a very bad function to use in interactive programs because 1549 This is a very bad function to use in interactive programs because
1548 it blocks, and a bad way to reduce concurrency because it is 1550 it blocks, and a bad way to reduce concurrency because it is
1549 inexact: Better use an "aio_group" together with a feed callback. 1551 inexact: Better use an "aio_group" together with a feed callback.
1550 1552
1551 Its main use is in scripts without an event loop - when you want to 1553 Its main use is in scripts without an event loop - when you want to
1552 stat a lot of files, you can write somehting like this: 1554 stat a lot of files, you can write something like this:
1553 1555
1554 IO::AIO::max_outstanding 32; 1556 IO::AIO::max_outstanding 32;
1555 1557
1556 for my $path (...) { 1558 for my $path (...) {
1557 aio_stat $path , ...; 1559 aio_stat $path , ...;
… …
1591 MISCELLANEOUS FUNCTIONS 1593 MISCELLANEOUS FUNCTIONS
1592 IO::AIO implements some functions that are useful when you want to use 1594 IO::AIO implements some functions that are useful when you want to use
1593 some "Advanced I/O" function not available to in Perl, without going the 1595 some "Advanced I/O" function not available to in Perl, without going the
1594 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*" 1596 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1595 counterpart. 1597 counterpart.
1598
1599 $numfd = IO::AIO::get_fdlimit
1600 This function is *EXPERIMENTAL* and subject to change.
1601
1602 Tries to find the current file descriptor limit and returns it, or
1603 "undef" and sets $! in case of an error. The limit is one larger
1604 than the highest valid file descriptor number.
1605
1606 IO::AIO::min_fdlimit [$numfd]
1607 This function is *EXPERIMENTAL* and subject to change.
1608
1609 Try to increase the current file descriptor limit(s) to at least
1610 $numfd by changing the soft or hard file descriptor resource limit.
1611 If $numfd is missing, it will try to set a very high limit, although
1612 this is not recommended when you know the actual minimum that you
1613 require.
1614
1615 If the limit cannot be raised enough, the function makes a
1616 best-effort attempt to increase the limit as much as possible, using
1617 various tricks, while still failing. You can query the resulting
1618 limit using "IO::AIO::get_fdlimit".
1619
1620 If an error occurs, returns "undef" and sets $!, otherwise returns
1621 true.
1596 1622
1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1623 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1598 Calls the "eio_sendfile_sync" function, which is like 1624 Calls the "eio_sendfile_sync" function, which is like
1599 "aio_sendfile", but is blocking (this makes most sense if you know 1625 "aio_sendfile", but is blocking (this makes most sense if you know
1600 the input data is likely cached already and the output filehandle is 1626 the input data is likely cached already and the output filehandle is
… …
1617 details). The following advice constants are available: 1643 details). The following advice constants are available:
1618 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1644 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1619 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1645 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1620 "IO::AIO::MADV_DONTNEED". 1646 "IO::AIO::MADV_DONTNEED".
1621 1647
1648 If $offset is negative, counts from the end. If $length is negative,
1649 the remaining length of the $scalar is used. If possible, $length
1650 will be reduced to fit into the $scalar.
1651
1622 On systems that do not implement "posix_madvise", this function 1652 On systems that do not implement "posix_madvise", this function
1623 returns ENOSYS, otherwise the return value of "posix_madvise". 1653 returns ENOSYS, otherwise the return value of "posix_madvise".
1624 1654
1625 IO::AIO::mprotect $scalar, $offset, $len, $protect 1655 IO::AIO::mprotect $scalar, $offset, $len, $protect
1626 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1656 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1627 $scalar (see its manpage for details). The following protect 1657 $scalar (see its manpage for details). The following protect
1628 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1658 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1629 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1659 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1630 1660
1661 If $offset is negative, counts from the end. If $length is negative,
1662 the remaining length of the $scalar is used. If possible, $length
1663 will be reduced to fit into the $scalar.
1664
1631 On systems that do not implement "mprotect", this function returns 1665 On systems that do not implement "mprotect", this function returns
1632 ENOSYS, otherwise the return value of "mprotect". 1666 ENOSYS, otherwise the return value of "mprotect".
1633 1667
1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1668 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1635 Memory-maps a file (or anonymous memory range) and attaches it to 1669 Memory-maps a file (or anonymous memory range) and attaches it to
1636 the given $scalar, which will act like a string scalar. Returns true 1670 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise. 1671 on success, and false otherwise.
1638 1672
1673 The scalar must exist, but its contents do not matter - this means
1674 you cannot use a nonexistant array or hash element. When in doubt,
1675 "undef" the scalar first.
1676
1639 The only operations allowed on the scalar are "substr"/"vec" that 1677 The only operations allowed on the mmapped scalar are
1640 don't change the string length, and most read-only operations such 1678 "substr"/"vec", which don't change the string length, and most
1641 as copying it or searching it with regexes and so on. 1679 read-only operations such as copying it or searching it with regexes
1680 and so on.
1642 1681
1643 Anything else is unsafe and will, at best, result in memory leaks. 1682 Anything else is unsafe and will, at best, result in memory leaks.
1644 1683
1645 The memory map associated with the $scalar is automatically removed 1684 The memory map associated with the $scalar is automatically removed
1646 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1685 when the $scalar is undef'd or destroyed, or when the
1647 "IO::AIO::munmap" functions are called. 1686 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1648 1687
1649 This calls the "mmap"(2) function internally. See your system's 1688 This calls the "mmap"(2) function internally. See your system's
1650 manual page for details on the $length, $prot and $flags parameters. 1689 manual page for details on the $length, $prot and $flags parameters.
1651 1690
1652 The $length must be larger than zero and smaller than the actual 1691 The $length must be larger than zero and smaller than the actual
… …
1739 Please refer to pipe2(2) for more info on the $flags, but at the 1778 Please refer to pipe2(2) for more info on the $flags, but at the
1740 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" 1779 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1741 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were 1780 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1742 supported. 1781 supported.
1743 1782
1783 Example: create a pipe race-free w.r.t. threads and fork:
1784
1785 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1786 or die "pipe2: $!\n";
1787
1788 $fh = IO::AIO::eventfd [$initval, [$flags]]
1789 This is a direct interface to the Linux eventfd(2) system call. The
1790 (unhelpful) defaults for $initval and $flags are 0 for both.
1791
1792 On success, the new eventfd filehandle is returned, otherwise
1793 returns "undef". If the eventfd syscall is missing, fails with
1794 "ENOSYS".
1795
1796 Please refer to eventfd(2) for more info on this call.
1797
1798 The following symbol flag values are available:
1799 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1800 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1801
1802 Example: create a new eventfd filehandle:
1803
1804 $fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
1805 or die "eventfd: $!\n";
1806
1807 $fh = IO::AIO::timerfd_create $clockid[, $flags]
1808 This is a direct interface to the Linux timerfd_create(2) system
1809 call. The (unhelpful) default for $flags is 0.
1810
1811 On success, the new timerfd filehandle is returned, otherwise
1812 returns "undef". If the eventfd syscall is missing, fails with
1813 "ENOSYS".
1814
1815 Please refer to timerfd_create(2) for more info on this call.
1816
1817 The following $clockid values are available:
1818 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
1819 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
1820 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
1821 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
1822
1823 The following $flags values are available (Linux 2.6.27):
1824 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
1825
1826 Example: create a new timerfd and set it to one-second repeated
1827 alarms, then wait for two alarms:
1828
1829 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
1830 or die "timerfd_create: $!\n";
1831
1832 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
1833 or die "timerfd_settime: $!\n";
1834
1835 for (1..2) {
1836 8 == sysread $fh, my $buf, 8
1837 or die "timerfd read failure\n";
1838
1839 printf "number of expirations (likely 1): %d\n",
1840 unpack "Q", $buf;
1841 }
1842
1843 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
1844 $new_interval, $nbw_value
1845 This is a direct interface to the Linux timerfd_settime(2) system
1846 call. Please refer to its manpage for more info on this call.
1847
1848 The new itimerspec is specified using two (possibly fractional)
1849 second values, $new_interval and $new_value).
1850
1851 On success, the current interval and value are returned (as per
1852 "timerfd_gettime"). On failure, the empty list is returned.
1853
1854 The following $flags values are available:
1855 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
1856
1857 See "IO::AIO::timerfd_create" for a full example.
1858
1859 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
1860 This is a direct interface to the Linux timerfd_gettime(2) system
1861 call. Please refer to its manpage for more info on this call.
1862
1863 On success, returns the current values of interval and value for the
1864 given timerfd (as potentially fractional second values). On failure,
1865 the empty list is returned.
1866
1744EVENT LOOP INTEGRATION 1867EVENT LOOP INTEGRATION
1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1868 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1746 automatically into many event loops: 1869 automatically into many event loops:
1747 1870
1748 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) 1871 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
… …
1797 forking, if "IO::AIO" was used in the parent. Calling it while 1920 forking, if "IO::AIO" was used in the parent. Calling it while
1798 IO::AIO is active in the process will result in undefined behaviour. 1921 IO::AIO is active in the process will result in undefined behaviour.
1799 Calling it at any time will also result in any undefined (by POSIX) 1922 Calling it at any time will also result in any undefined (by POSIX)
1800 behaviour. 1923 behaviour.
1801 1924
1925 LINUX-SPECIFIC CALLS
1926 When a call is documented as "linux-specific" then this means it
1927 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
1928 availability and compatibility of such calls regardless of the platform
1929 it is compiled on, so platforms such as FreeBSD which often implement
1930 these calls will work. When in doubt, call them and see if they fail wth
1931 "ENOSYS".
1932
1802 MEMORY USAGE 1933 MEMORY USAGE
1803 Per-request usage: 1934 Per-request usage:
1804 1935
1805 Each aio request uses - depending on your architecture - around 100-200 1936 Each aio request uses - depending on your architecture - around 100-200
1806 bytes of memory. In addition, stat requests need a stat buffer (possibly 1937 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1816 In the execution phase, some aio requests require more memory for 1947 In the execution phase, some aio requests require more memory for
1817 temporary buffers, and each thread requires a stack and other data 1948 temporary buffers, and each thread requires a stack and other data
1818 structures (usually around 16k-128k, depending on the OS). 1949 structures (usually around 16k-128k, depending on the OS).
1819 1950
1820KNOWN BUGS 1951KNOWN BUGS
1821 Known bugs will be fixed in the next release. 1952 Known bugs will be fixed in the next release :)
1953
1954KNOWN ISSUES
1955 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
1956 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
1957 non-created hash slots or other scalars I didn't think of. It's best to
1958 avoid such and either use scalar variables or making sure that the
1959 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
1960
1961 I am not sure anything can be done about this, so this is considered a
1962 known issue, rather than a bug.
1822 1963
1823SEE ALSO 1964SEE ALSO
1824 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 1965 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1825 more natural syntax. 1966 more natural syntax.
1826 1967

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