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Revision 1.57 by root, Mon Jan 18 11:53:09 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.
… …
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
… …
371 380
372 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 381 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
374 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
375 $offset into the scalar given by $data and offset $dataoffset and 384 $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 385 calls the callback with the actual number of bytes transferred (or
377 error, just like the syscall). 386 -1 on error, just like the syscall).
378 387
379 "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
380 offset plus the actual number of bytes read. 389 offset plus the actual number of bytes read.
381 390
382 If $offset is undefined, then the current file descriptor offset 391 If $offset is undefined, then the current file descriptor offset
… …
439 As native sendfile syscalls (as practically any non-POSIX interface 448 As native sendfile syscalls (as practically any non-POSIX interface
440 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
441 rather buggy on many systems, this implementation tries to work 450 rather buggy on many systems, this implementation tries to work
442 around some known bugs in Linux and FreeBSD kernels (probably 451 around some known bugs in Linux and FreeBSD kernels (probably
443 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
444 the return value of "aio_sendfile" - fewre bytes than expected might 453 the return value of "aio_sendfile" - fewer bytes than expected might
445 have been transferred. 454 have been transferred.
446 455
447 aio_readahead $fh,$offset,$length, $callback->($retval) 456 aio_readahead $fh,$offset,$length, $callback->($retval)
448 "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
449 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
… …
453 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
454 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
455 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
456 is left unchanged. 465 is left unchanged.
457 466
458 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
459 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
460 similar effect. 469 similar effect.
461 470
462 aio_stat $fh_or_path, $callback->($status) 471 aio_stat $fh_or_path, $callback->($status)
463 aio_lstat $fh, $callback->($status) 472 aio_lstat $fh, $callback->($status)
… …
530 namemax => 255, 539 namemax => 255,
531 frsize => 1024, 540 frsize => 1024,
532 fsid => 1810 541 fsid => 1810
533 } 542 }
534 543
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) 544 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
621 Works like perl's "utime" function (including the special case of 545 Works like perl's "utime" function (including the special case of
622 $atime and $mtime being undef). Fractional times are supported if 546 $atime and $mtime being undef). Fractional times are supported if
623 the underlying syscalls support them. 547 the underlying syscalls support them.
624 548
… …
655 $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
656 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 580 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
657 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 581 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
658 582
659 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
660 (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
661 (see your fallocate(2) manpage). 587 fallocate(2) manpage).
662 588
663 The file system block size used by "fallocate" is presumably the 589 The file system block size used by "fallocate" is presumably the
664 "f_bsize" returned by "statvfs". 590 "f_bsize" returned by "statvfs", but different filesystems and
591 filetypes can dictate other limitations.
665 592
666 If "fallocate" isn't available or cannot be emulated (currently no 593 If "fallocate" isn't available or cannot be emulated (currently no
667 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 594 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
668 595
669 aio_chmod $fh_or_path, $mode, $callback->($status) 596 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
712 rename(2) and call the callback with the result code. 639 rename(2) and call the callback with the result code.
713 640
714 On systems that support the AIO::WD working directory abstraction 641 On systems that support the AIO::WD working directory abstraction
715 natively, the case "[$wd, "."]" as $srcpath is specialcased - 642 natively, the case "[$wd, "."]" as $srcpath is specialcased -
716 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".
717 659
718 aio_mkdir $pathname, $mode, $callback->($status) 660 aio_mkdir $pathname, $mode, $callback->($status)
719 Asynchronously mkdir (create) a directory and call the callback with 661 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 662 the result code. $mode will be modified by the umask at the time the
721 request is executed, so do not change your umask. 663 request is executed, so do not change your umask.
… …
796 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
797 $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
798 flag therefore indicates that all $type's are known, which can 740 flag therefore indicates that all $type's are known, which can
799 be used to speed up some algorithms. 741 be used to speed up some algorithms.
800 742
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
801 aio_load $pathname, $data, $callback->($status) 770 aio_load $pathname, $data, $callback->($status)
802 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
803 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.
804 776
805 aio_copy $srcpath, $dstpath, $callback->($status) 777 aio_copy $srcpath, $dstpath, $callback->($status)
806 Try to copy the *file* (directories not supported as either source 778 Try to copy the *file* (directories not supported as either source
807 or destination) from $srcpath to $dstpath and call the callback with 779 or destination) from $srcpath to $dstpath and call the callback with
808 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.
809 783
810 This is a composite request that creates the destination file with 784 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 785 mode 0200 and copies the contents of the source file into it using
812 "aio_sendfile", followed by restoring atime, mtime, access mode and 786 "aio_sendfile", followed by restoring atime, mtime, access mode and
813 uid/gid, in that order. 787 uid/gid, in that order.
… …
830 to efficiently separate the entries of directory $path into two sets 804 to efficiently separate the entries of directory $path into two sets
831 of names, directories you can recurse into (directories), and ones 805 of names, directories you can recurse into (directories), and ones
832 you cannot recurse into (everything else, including symlinks to 806 you cannot recurse into (everything else, including symlinks to
833 directories). 807 directories).
834 808
835 "aio_scandir" is a composite request that creates of many sub 809 "aio_scandir" is a composite request that generates many sub
836 requests_ $maxreq specifies the maximum number of outstanding aio 810 requests. $maxreq specifies the maximum number of outstanding aio
837 requests that this function generates. If it is "<= 0", then a 811 requests that this function generates. If it is "<= 0", then a
838 suitable default will be chosen (currently 4). 812 suitable default will be chosen (currently 4).
839 813
840 On error, the callback is called without arguments, otherwise it 814 On error, the callback is called without arguments, otherwise it
841 receives two array-refs with path-relative entry names. 815 receives two array-refs with path-relative entry names.
… …
888 Delete a directory tree starting (and including) $path, return the 862 Delete a directory tree starting (and including) $path, return the
889 status of the final "rmdir" only. This is a composite request that 863 status of the final "rmdir" only. This is a composite request that
890 uses "aio_scandir" to recurse into and rmdir directories, and unlink 864 uses "aio_scandir" to recurse into and rmdir directories, and unlink
891 everything else. 865 everything else.
892 866
867 aio_fcntl $fh, $cmd, $arg, $callback->($status)
868 aio_ioctl $fh, $request, $buf, $callback->($status)
869 These work just like the "fcntl" and "ioctl" built-in functions,
870 except they execute asynchronously and pass the return value to the
871 callback.
872
873 Both calls can be used for a lot of things, some of which make more
874 sense to run asynchronously in their own thread, while some others
875 make less sense. For example, calls that block waiting for external
876 events, such as locking, will also lock down an I/O thread while it
877 is waiting, which can deadlock the whole I/O system. At the same
878 time, there might be no alternative to using a thread to wait.
879
880 So in general, you should only use these calls for things that do
881 (filesystem) I/O, not for things that wait for other events
882 (network, other processes), although if you are careful and know
883 what you are doing, you still can.
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
893 aio_sync $callback->($status) 915 aio_sync $callback->($status)
894 Asynchronously call sync and call the callback when finished. 916 Asynchronously call sync and call the callback when finished.
895 917
896 aio_fsync $fh, $callback->($status) 918 aio_fsync $fh, $callback->($status)
897 Asynchronously call fsync on the given filehandle and call the 919 Asynchronously call fsync on the given filehandle and call the
… …
933 Future versions of this function might fall back to other methods 955 Future versions of this function might fall back to other methods
934 when "fsync" on the directory fails (such as calling "sync"). 956 when "fsync" on the directory fails (such as calling "sync").
935 957
936 Passes 0 when everything went ok, and -1 on error. 958 Passes 0 when everything went ok, and -1 on error.
937 959
938 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 960 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
939 $callback->($status) 961 $callback->($status)
940 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
941 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
942 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,
943 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
… …
945 967
946 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
947 memory area starting at $offset in the string and ending $length 969 memory area starting at $offset in the string and ending $length
948 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
949 $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
950 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
951 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 973 an optional "IO::AIO::MS_INVALIDATE".
952 974
953 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 975 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
954 $callback->($status) 976 $callback->($status)
955 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
956 mmap(2)ed scalars. 978 mmap(2)ed scalars.
… …
1042 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1064 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1043 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1065 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1044 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1066 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1045 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1067 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1046 1068
1047 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
1048 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
1049 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
1050 number of extents. The code works around all these issues if $count 1072 large number of extents. The code (only) works around all these
1051 is undef. 1073 issues if $count is "undef".
1052 1074
1053 aio_group $callback->(...) 1075 aio_group $callback->(...)
1054 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
1055 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
1056 to bundle many requests into a single, composite, request with a 1078 to bundle many requests into a single, composite, request with a
… …
1165 There are some caveats: when directories get renamed (or deleted), the 1187 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 1188 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, 1189 nowhere at all), while the directory fd, if available on the system,
1168 will still point to the original directory. Most functions accepting a 1190 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 1191 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 1192 older systems. Some functions (such as "aio_realpath") will always rely
1171 string form of the pathname. 1193 on the string form of the pathname.
1172 1194
1173 So this functionality is mainly useful to get some protection against 1195 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 1196 "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 1197 future reference, and to speed up doing many operations in the same
1176 directory (e.g. when stat'ing all files in a directory). 1198 directory (e.g. when stat'ing all files in a directory).
… …
1527 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
1528 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
1529 inexact: Better use an "aio_group" together with a feed callback. 1551 inexact: Better use an "aio_group" together with a feed callback.
1530 1552
1531 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
1532 stat a lot of files, you can write somehting like this: 1554 stat a lot of files, you can write something like this:
1533 1555
1534 IO::AIO::max_outstanding 32; 1556 IO::AIO::max_outstanding 32;
1535 1557
1536 for my $path (...) { 1558 for my $path (...) {
1537 aio_stat $path , ...; 1559 aio_stat $path , ...;
… …
1571 MISCELLANEOUS FUNCTIONS 1593 MISCELLANEOUS FUNCTIONS
1572 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
1573 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
1574 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*" 1596 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1575 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.
1576 1622
1577 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1623 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1578 Calls the "eio_sendfile_sync" function, which is like 1624 Calls the "eio_sendfile_sync" function, which is like
1579 "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
1580 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
… …
1597 details). The following advice constants are available: 1643 details). The following advice constants are available:
1598 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1644 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1599 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1645 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1600 "IO::AIO::MADV_DONTNEED". 1646 "IO::AIO::MADV_DONTNEED".
1601 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
1602 On systems that do not implement "posix_madvise", this function 1652 On systems that do not implement "posix_madvise", this function
1603 returns ENOSYS, otherwise the return value of "posix_madvise". 1653 returns ENOSYS, otherwise the return value of "posix_madvise".
1604 1654
1605 IO::AIO::mprotect $scalar, $offset, $len, $protect 1655 IO::AIO::mprotect $scalar, $offset, $len, $protect
1606 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1656 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1607 $scalar (see its manpage for details). The following protect 1657 $scalar (see its manpage for details). The following protect
1608 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1658 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1609 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1659 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1610 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
1611 On systems that do not implement "mprotect", this function returns 1665 On systems that do not implement "mprotect", this function returns
1612 ENOSYS, otherwise the return value of "mprotect". 1666 ENOSYS, otherwise the return value of "mprotect".
1613 1667
1614 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1668 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1615 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
1616 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
1617 on success, and false otherwise. 1671 on success, and false otherwise.
1618 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
1619 The only operations allowed on the scalar are "substr"/"vec" that 1677 The only operations allowed on the mmapped scalar are
1620 don't change the string length, and most read-only operations such 1678 "substr"/"vec", which don't change the string length, and most
1621 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.
1622 1681
1623 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.
1624 1683
1625 The memory map associated with the $scalar is automatically removed 1684 The memory map associated with the $scalar is automatically removed
1626 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1685 when the $scalar is undef'd or destroyed, or when the
1627 "IO::AIO::munmap" functions are called. 1686 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1628 1687
1629 This calls the "mmap"(2) function internally. See your system's 1688 This calls the "mmap"(2) function internally. See your system's
1630 manual page for details on the $length, $prot and $flags parameters. 1689 manual page for details on the $length, $prot and $flags parameters.
1631 1690
1632 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
… …
1638 1697
1639 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1698 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1640 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1699 "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 1700 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1642 "MAP_ANON" if your system only provides this constant), 1701 "MAP_ANON" if your system only provides this constant),
1702 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1643 "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1703 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1644 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE", 1704 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1645 "IO::AIO::MAP_NONBLOCK", "IO::AIO::MAP_FIXED", 1705 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1646 "IO::AIO::MAP_GROWSDOWN", "IO::AIO::MAP_32BIT", 1706 "IO::AIO::MAP_STACK".
1647 "IO::AIO::MAP_HUGETLB" or "IO::AIO::MAP_STACK".
1648 1707
1649 If $fh is "undef", then a file descriptor of -1 is passed. 1708 If $fh is "undef", then a file descriptor of -1 is passed.
1650 1709
1651 $offset is the offset from the start of the file - it generally must 1710 $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. 1711 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1718 1777
1719 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 $flags, but at the
1720 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" 1779 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1721 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were 1780 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1722 supported. 1781 supported.
1782
1783 Example: create a pipe race-free w.r.t. threads and fork:
1784
1785 my ($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.
1723 1866
1724EVENT LOOP INTEGRATION 1867EVENT LOOP INTEGRATION
1725 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1868 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1726 automatically into many event loops: 1869 automatically into many event loops:
1727 1870
… …
1777 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
1778 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.
1779 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)
1780 behaviour. 1923 behaviour.
1781 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
1782 MEMORY USAGE 1933 MEMORY USAGE
1783 Per-request usage: 1934 Per-request usage:
1784 1935
1785 Each aio request uses - depending on your architecture - around 100-200 1936 Each aio request uses - depending on your architecture - around 100-200
1786 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
… …
1796 In the execution phase, some aio requests require more memory for 1947 In the execution phase, some aio requests require more memory for
1797 temporary buffers, and each thread requires a stack and other data 1948 temporary buffers, and each thread requires a stack and other data
1798 structures (usually around 16k-128k, depending on the OS). 1949 structures (usually around 16k-128k, depending on the OS).
1799 1950
1800KNOWN BUGS 1951KNOWN BUGS
1801 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.
1802 1963
1803SEE ALSO 1964SEE ALSO
1804 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
1805 more natural syntax. 1966 more natural syntax.
1806 1967

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