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Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC vs.
Revision 1.61 by root, Sun Aug 12 06:07:06 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
233 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
226 IO::AIO::madvise $scalar, $offset, $length, $advice 234 IO::AIO::madvise $scalar, $offset, $length, $advice
227 IO::AIO::mprotect $scalar, $offset, $length, $protect 235 IO::AIO::mprotect $scalar, $offset, $length, $protect
228 IO::AIO::munlock $scalar, $offset = 0, $length = undef 236 IO::AIO::munlock $scalar, $offset = 0, $length = undef
229 IO::AIO::munlockall 237 IO::AIO::munlockall
230 238
… …
332 "O_APPEND"), the following POSIX and non-POSIX constants are 340 "O_APPEND"), the following POSIX and non-POSIX constants are
333 available (missing ones on your system are, as usual, 0): 341 available (missing ones on your system are, as usual, 0):
334 342
335 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 343 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
336 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 344 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
337 "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"
338 "O_TTY_INIT". 346 and "O_ACCMODE".
339 347
340 aio_close $fh, $callback->($status) 348 aio_close $fh, $callback->($status)
341 Asynchronously close a file and call the callback with the result 349 Asynchronously close a file and call the callback with the result
342 code. 350 code.
343 351
… …
373 381
374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
376 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
377 $offset into the scalar given by $data and offset $dataoffset and 385 $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 386 calls the callback with the actual number of bytes transferred (or
379 error, just like the syscall). 387 -1 on error, just like the syscall).
380 388
381 "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
382 offset plus the actual number of bytes read. 390 offset plus the actual number of bytes read.
383 391
384 If $offset is undefined, then the current file descriptor offset 392 If $offset is undefined, then the current file descriptor offset
… …
441 As native sendfile syscalls (as practically any non-POSIX interface 449 As native sendfile syscalls (as practically any non-POSIX interface
442 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
443 rather buggy on many systems, this implementation tries to work 451 rather buggy on many systems, this implementation tries to work
444 around some known bugs in Linux and FreeBSD kernels (probably 452 around some known bugs in Linux and FreeBSD kernels (probably
445 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
446 the return value of "aio_sendfile" - fewre bytes than expected might 454 the return value of "aio_sendfile" - fewer bytes than expected might
447 have been transferred. 455 have been transferred.
448 456
449 aio_readahead $fh,$offset,$length, $callback->($retval) 457 aio_readahead $fh,$offset,$length, $callback->($retval)
450 "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
451 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
… …
455 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
456 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
457 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
458 is left unchanged. 466 is left unchanged.
459 467
460 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
461 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
462 similar effect. 470 similar effect.
463 471
464 aio_stat $fh_or_path, $callback->($status) 472 aio_stat $fh_or_path, $callback->($status)
465 aio_lstat $fh, $callback->($status) 473 aio_lstat $fh, $callback->($status)
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481 back on traditional behaviour). 489 back on traditional behaviour).
482 490
483 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 491 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
484 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 492 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
485 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 493 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
494
495 To access higher resolution stat timestamps, see "SUBSECOND STAT
496 TIME ACCESS".
486 497
487 Example: Print the length of /etc/passwd: 498 Example: Print the length of /etc/passwd:
488 499
489 aio_stat "/etc/passwd", sub { 500 aio_stat "/etc/passwd", sub {
490 $_[0] and die "stat failed: $!"; 501 $_[0] and die "stat failed: $!";
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532 namemax => 255, 543 namemax => 255,
533 frsize => 1024, 544 frsize => 1024,
534 fsid => 1810 545 fsid => 1810
535 } 546 }
536 547
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) 548 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
623 Works like perl's "utime" function (including the special case of 549 Works like perl's "utime" function (including the special case of
624 $atime and $mtime being undef). Fractional times are supported if 550 $atime and $mtime being undef). Fractional times are supported if
625 the underlying syscalls support them. 551 the underlying syscalls support them.
626 552
… …
657 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate 583 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
658 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 584 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
659 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 585 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
660 586
661 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range 587 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 588 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
589 "FALLOC_FL_INSERT_RANGE" to insert a range and
590 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
663 (see your fallocate(2) manpage). 591 fallocate(2) manpage).
664 592
665 The file system block size used by "fallocate" is presumably the 593 The file system block size used by "fallocate" is presumably the
666 "f_bsize" returned by "statvfs". 594 "f_bsize" returned by "statvfs", but different filesystems and
595 filetypes can dictate other limitations.
667 596
668 If "fallocate" isn't available or cannot be emulated (currently no 597 If "fallocate" isn't available or cannot be emulated (currently no
669 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 598 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
670 599
671 aio_chmod $fh_or_path, $mode, $callback->($status) 600 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
715 644
716 On systems that support the AIO::WD working directory abstraction 645 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased - 646 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd. 647 instead of failing, "rename" is called on the absolute path of $wd.
719 648
649 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
650 Basically a version of "aio_rename" with an additional $flags
651 argument. Calling this with "$flags=0" is the same as calling
652 "aio_rename".
653
654 Non-zero flags are currently only supported on GNU/Linux systems
655 that support renameat2. Other systems fail with "ENOSYS" in this
656 case.
657
658 The following constants are available (missing ones are, as usual
659 0), see renameat2(2) for details:
660
661 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
662 "IO::AIO::RENAME_WHITEOUT".
663
720 aio_mkdir $pathname, $mode, $callback->($status) 664 aio_mkdir $pathname, $mode, $callback->($status)
721 Asynchronously mkdir (create) a directory and call the callback with 665 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 666 the result code. $mode will be modified by the umask at the time the
723 request is executed, so do not change your umask. 667 request is executed, so do not change your umask.
724 668
… …
746 The flags are a combination of the following constants, ORed 690 The flags are a combination of the following constants, ORed
747 together (the flags will also be passed to the callback, possibly 691 together (the flags will also be passed to the callback, possibly
748 modified): 692 modified):
749 693
750 IO::AIO::READDIR_DENTS 694 IO::AIO::READDIR_DENTS
751 When this flag is off, then the callback gets an arrayref 695 Normally the callback gets an arrayref consisting of names only
752 consisting of names only (as with "aio_readdir"), otherwise it 696 (as with "aio_readdir"). If this flag is set, then the callback
753 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 697 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
754 describing a single directory entry in more detail. 698 describing a single directory entry in more detail:
755 699
756 $name is the name of the entry. 700 $name is the name of the entry.
757 701
758 $type is one of the "IO::AIO::DT_xxx" constants: 702 $type is one of the "IO::AIO::DT_xxx" constants:
759 703
760 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 704 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
761 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 705 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
762 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 706 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
763 707
764 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 708 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
765 you need to know, you have to run stat yourself. Also, for speed 709 you need to know, you have to run stat yourself. Also, for
766 reasons, the $type scalars are read-only: you can not modify 710 speed/memory reasons, the $type scalars are read-only: you must
767 them. 711 not modify them.
768 712
769 $inode is the inode number (which might not be exact on systems 713 $inode is the inode number (which might not be exact on systems
770 with 64 bit inode numbers and 32 bit perls). This field has 714 with 64 bit inode numbers and 32 bit perls). This field has
771 unspecified content on systems that do not deliver the inode 715 unspecified content on systems that do not deliver the inode
772 information. 716 information.
… …
784 of which names with short names are tried first. 728 of which names with short names are tried first.
785 729
786 IO::AIO::READDIR_STAT_ORDER 730 IO::AIO::READDIR_STAT_ORDER
787 When this flag is set, then the names will be returned in an 731 When this flag is set, then the names will be returned in an
788 order suitable for stat()'ing each one. That is, when you plan 732 order suitable for stat()'ing each one. That is, when you plan
789 to stat() all files in the given directory, then the returned 733 to stat() most or all files in the given directory, then the
790 order will likely be fastest. 734 returned order will likely be faster.
791 735
792 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 736 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
793 specified, then the likely dirs come first, resulting in a less 737 specified, then the likely dirs come first, resulting in a less
794 optimal stat order. 738 optimal stat order for stat'ing all entries, but likely a more
739 optimal order for finding subdirectories.
795 740
796 IO::AIO::READDIR_FOUND_UNKNOWN 741 IO::AIO::READDIR_FOUND_UNKNOWN
797 This flag should not be set when calling "aio_readdirx". 742 This flag should not be set when calling "aio_readdirx".
798 Instead, it is being set by "aio_readdirx", when any of the 743 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 744 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
800 flag therefore indicates that all $type's are known, which can 745 flag therefore indicates that all $type's are known, which can
801 be used to speed up some algorithms. 746 be used to speed up some algorithms.
802 747
748 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
749 Opens, reads and closes the given file. The data is put into $data,
750 which is resized as required.
751
752 If $offset is negative, then it is counted from the end of the file.
753
754 If $length is zero, then the remaining length of the file is used.
755 Also, in this case, the same limitations to modifying $data apply as
756 when IO::AIO::mmap is used, i.e. it must only be modified in-place
757 with "substr". If the size of the file is known, specifying a
758 non-zero $length results in a performance advantage.
759
760 This request is similar to the older "aio_load" request, but since
761 it is a single request, it might be more efficient to use.
762
763 Example: load /etc/passwd into $passwd.
764
765 my $passwd;
766 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
767 $_[0] >= 0
768 or die "/etc/passwd: $!\n";
769
770 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
771 print $passwd;
772 };
773 IO::AIO::flush;
774
803 aio_load $pathname, $data, $callback->($status) 775 aio_load $pathname, $data, $callback->($status)
804 This is a composite request that tries to fully load the given file 776 This is a composite request that tries to fully load the given file
805 into memory. Status is the same as with aio_read. 777 into memory. Status is the same as with aio_read.
778
779 Using "aio_slurp" might be more efficient, as it is a single
780 request.
806 781
807 aio_copy $srcpath, $dstpath, $callback->($status) 782 aio_copy $srcpath, $dstpath, $callback->($status)
808 Try to copy the *file* (directories not supported as either source 783 Try to copy the *file* (directories not supported as either source
809 or destination) from $srcpath to $dstpath and call the callback with 784 or destination) from $srcpath to $dstpath and call the callback with
810 a status of 0 (ok) or -1 (error, see $!). 785 a status of 0 (ok) or -1 (error, see $!).
786
787 Existing destination files will be truncated.
811 788
812 This is a composite request that creates the destination file with 789 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 790 mode 0200 and copies the contents of the source file into it using
814 "aio_sendfile", followed by restoring atime, mtime, access mode and 791 "aio_sendfile", followed by restoring atime, mtime, access mode and
815 uid/gid, in that order. 792 uid/gid, in that order.
… …
832 to efficiently separate the entries of directory $path into two sets 809 to efficiently separate the entries of directory $path into two sets
833 of names, directories you can recurse into (directories), and ones 810 of names, directories you can recurse into (directories), and ones
834 you cannot recurse into (everything else, including symlinks to 811 you cannot recurse into (everything else, including symlinks to
835 directories). 812 directories).
836 813
837 "aio_scandir" is a composite request that creates of many sub 814 "aio_scandir" is a composite request that generates many sub
838 requests_ $maxreq specifies the maximum number of outstanding aio 815 requests. $maxreq specifies the maximum number of outstanding aio
839 requests that this function generates. If it is "<= 0", then a 816 requests that this function generates. If it is "<= 0", then a
840 suitable default will be chosen (currently 4). 817 suitable default will be chosen (currently 4).
841 818
842 On error, the callback is called without arguments, otherwise it 819 On error, the callback is called without arguments, otherwise it
843 receives two array-refs with path-relative entry names. 820 receives two array-refs with path-relative entry names.
… …
908 So in general, you should only use these calls for things that do 885 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 886 (filesystem) I/O, not for things that wait for other events
910 (network, other processes), although if you are careful and know 887 (network, other processes), although if you are careful and know
911 what you are doing, you still can. 888 what you are doing, you still can.
912 889
890 The following constants are available (missing ones are, as usual
891 0):
892
893 "F_DUPFD_CLOEXEC",
894
895 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
896
897 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
898 "FIDEDUPERANGE".
899
900 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
901 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
902
903 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
904 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
905 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
906
907 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
908 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
909 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
910 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
911 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
912
913 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
914 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
915 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
916 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
917 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
918 "FS_XFLAG_HASATTR",
919
913 aio_sync $callback->($status) 920 aio_sync $callback->($status)
914 Asynchronously call sync and call the callback when finished. 921 Asynchronously call sync and call the callback when finished.
915 922
916 aio_fsync $fh, $callback->($status) 923 aio_fsync $fh, $callback->($status)
917 Asynchronously call fsync on the given filehandle and call the 924 Asynchronously call fsync on the given filehandle and call the
… …
953 Future versions of this function might fall back to other methods 960 Future versions of this function might fall back to other methods
954 when "fsync" on the directory fails (such as calling "sync"). 961 when "fsync" on the directory fails (such as calling "sync").
955 962
956 Passes 0 when everything went ok, and -1 on error. 963 Passes 0 when everything went ok, and -1 on error.
957 964
958 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 965 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
959 $callback->($status) 966 $callback->($status)
960 This is a rather advanced IO::AIO call, which only works on 967 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 968 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, 969 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 970 note that the scalar must only be modified in-place while an aio
… …
965 972
966 It calls the "msync" function of your OS, if available, with the 973 It calls the "msync" function of your OS, if available, with the
967 memory area starting at $offset in the string and ending $length 974 memory area starting at $offset in the string and ending $length
968 bytes later. If $length is negative, counts from the end, and if 975 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 976 $length is "undef", then it goes till the end of the string. The
970 flags can be a combination of "IO::AIO::MS_ASYNC", 977 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
971 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 978 an optional "IO::AIO::MS_INVALIDATE".
972 979
973 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 980 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
974 $callback->($status) 981 $callback->($status)
975 This is a rather advanced IO::AIO call, which works best on 982 This is a rather advanced IO::AIO call, which works best on
976 mmap(2)ed scalars. 983 mmap(2)ed scalars.
… …
1062 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1069 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1063 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1070 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1064 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1071 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1065 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1072 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1066 1073
1067 At the time of this writing (Linux 3.2), this requets is unreliable 1074 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 1075 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 1076 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 1077 large number of extents. The code (only) works around all these
1071 is undef. 1078 issues if $count is "undef".
1072 1079
1073 aio_group $callback->(...) 1080 aio_group $callback->(...)
1074 This is a very special aio request: Instead of doing something, it 1081 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 1082 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 1083 to bundle many requests into a single, composite, request with a
… …
1185 There are some caveats: when directories get renamed (or deleted), the 1192 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 1193 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, 1194 nowhere at all), while the directory fd, if available on the system,
1188 will still point to the original directory. Most functions accepting a 1195 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 1196 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 1197 older systems. Some functions (such as "aio_realpath") will always rely
1191 string form of the pathname. 1198 on the string form of the pathname.
1192 1199
1193 So this functionality is mainly useful to get some protection against 1200 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 1201 "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 1202 future reference, and to speed up doing many operations in the same
1196 directory (e.g. when stat'ing all files in a directory). 1203 directory (e.g. when stat'ing all files in a directory).
… …
1547 This is a very bad function to use in interactive programs because 1554 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 1555 it blocks, and a bad way to reduce concurrency because it is
1549 inexact: Better use an "aio_group" together with a feed callback. 1556 inexact: Better use an "aio_group" together with a feed callback.
1550 1557
1551 Its main use is in scripts without an event loop - when you want to 1558 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: 1559 stat a lot of files, you can write something like this:
1553 1560
1554 IO::AIO::max_outstanding 32; 1561 IO::AIO::max_outstanding 32;
1555 1562
1556 for my $path (...) { 1563 for my $path (...) {
1557 aio_stat $path , ...; 1564 aio_stat $path , ...;
… …
1586 1593
1587 IO::AIO::npending 1594 IO::AIO::npending
1588 Returns the number of requests currently in the pending state 1595 Returns the number of requests currently in the pending state
1589 (executed, but not yet processed by poll_cb). 1596 (executed, but not yet processed by poll_cb).
1590 1597
1598 SUBSECOND STAT TIME ACCESS
1599 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1600 generally find access/modification and change times with subsecond time
1601 accuracy of the system supports it, but perl's built-in functions only
1602 return the integer part.
1603
1604 The following functions return the timestamps of the most recent stat
1605 with subsecond precision on most systems and work both after
1606 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1607 value is only meaningful after a successful "stat"/"lstat" call, or
1608 during/after a successful "aio_stat"/"aio_lstat" callback.
1609
1610 This is similar to the Time::HiRes "stat" functions, but can return full
1611 resolution without rounding and work with standard perl "stat",
1612 alleviating the need to call the special "Time::HiRes" functions, which
1613 do not act like their perl counterparts.
1614
1615 On operating systems or file systems where subsecond time resolution is
1616 not supported or could not be detected, a fractional part of 0 is
1617 returned, so it is always safe to call these functions.
1618
1619 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime
1620 Return the access, modication or change time, respectively,
1621 including fractional part. Due to the limited precision of floating
1622 point, the accuracy on most platforms is only a bit better than
1623 milliseconds for times around now - see the *nsec* function family,
1624 below, for full accuracy.
1625
1626 ($atime, $mtime, $ctime, ...) = IO::AIO::st_xtime
1627 Returns access, modification and change time all in one go, and
1628 maybe more times in the future version.
1629
1630 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1631 IO::AIO::st_ctimensec
1632 Return the fractional access, modifcation or change time, in
1633 nanoseconds, as an integer in the range 0 to 999999999.
1634
1635 ($atime, $mtime, $ctime, ...) = IO::AIO::st_xtimensec
1636 Like the functions above, but returns all three times in one go (and
1637 maybe more in future versions).
1638
1639 Example: print the high resolution modification time of /etc, using
1640 "stat", and "IO::AIO::aio_stat".
1641
1642 if (stat "/etc") {
1643 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1644 }
1645
1646 IO::AIO::aio_stat "/etc", sub {
1647 $_[0]
1648 and return;
1649
1650 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1651 };
1652
1653 IO::AIO::flush;
1654
1655 Output of the awbove on my system, showing reduced and full accuracy:
1656
1657 stat(/etc) mtime: 1534043702.020808
1658 aio_stat(/etc) mtime: 1534043702.020807792
1659
1591 MISCELLANEOUS FUNCTIONS 1660 MISCELLANEOUS FUNCTIONS
1592 IO::AIO implements some functions that are useful when you want to use 1661 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 1662 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_*" 1663 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1595 counterpart. 1664 counterpart.
1665
1666 $numfd = IO::AIO::get_fdlimit
1667 This function is *EXPERIMENTAL* and subject to change.
1668
1669 Tries to find the current file descriptor limit and returns it, or
1670 "undef" and sets $! in case of an error. The limit is one larger
1671 than the highest valid file descriptor number.
1672
1673 IO::AIO::min_fdlimit [$numfd]
1674 This function is *EXPERIMENTAL* and subject to change.
1675
1676 Try to increase the current file descriptor limit(s) to at least
1677 $numfd by changing the soft or hard file descriptor resource limit.
1678 If $numfd is missing, it will try to set a very high limit, although
1679 this is not recommended when you know the actual minimum that you
1680 require.
1681
1682 If the limit cannot be raised enough, the function makes a
1683 best-effort attempt to increase the limit as much as possible, using
1684 various tricks, while still failing. You can query the resulting
1685 limit using "IO::AIO::get_fdlimit".
1686
1687 If an error occurs, returns "undef" and sets $!, otherwise returns
1688 true.
1596 1689
1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1690 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1598 Calls the "eio_sendfile_sync" function, which is like 1691 Calls the "eio_sendfile_sync" function, which is like
1599 "aio_sendfile", but is blocking (this makes most sense if you know 1692 "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 1693 the input data is likely cached already and the output filehandle is
… …
1617 details). The following advice constants are available: 1710 details). The following advice constants are available:
1618 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1711 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1619 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1712 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1620 "IO::AIO::MADV_DONTNEED". 1713 "IO::AIO::MADV_DONTNEED".
1621 1714
1715 If $offset is negative, counts from the end. If $length is negative,
1716 the remaining length of the $scalar is used. If possible, $length
1717 will be reduced to fit into the $scalar.
1718
1622 On systems that do not implement "posix_madvise", this function 1719 On systems that do not implement "posix_madvise", this function
1623 returns ENOSYS, otherwise the return value of "posix_madvise". 1720 returns ENOSYS, otherwise the return value of "posix_madvise".
1624 1721
1625 IO::AIO::mprotect $scalar, $offset, $len, $protect 1722 IO::AIO::mprotect $scalar, $offset, $len, $protect
1626 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1723 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1627 $scalar (see its manpage for details). The following protect 1724 $scalar (see its manpage for details). The following protect
1628 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1725 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1629 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1726 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1630 1727
1728 If $offset is negative, counts from the end. If $length is negative,
1729 the remaining length of the $scalar is used. If possible, $length
1730 will be reduced to fit into the $scalar.
1731
1631 On systems that do not implement "mprotect", this function returns 1732 On systems that do not implement "mprotect", this function returns
1632 ENOSYS, otherwise the return value of "mprotect". 1733 ENOSYS, otherwise the return value of "mprotect".
1633 1734
1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1735 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1635 Memory-maps a file (or anonymous memory range) and attaches it to 1736 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 1737 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise. 1738 on success, and false otherwise.
1638 1739
1740 The scalar must exist, but its contents do not matter - this means
1741 you cannot use a nonexistant array or hash element. When in doubt,
1742 "undef" the scalar first.
1743
1639 The only operations allowed on the scalar are "substr"/"vec" that 1744 The only operations allowed on the mmapped scalar are
1640 don't change the string length, and most read-only operations such 1745 "substr"/"vec", which don't change the string length, and most
1641 as copying it or searching it with regexes and so on. 1746 read-only operations such as copying it or searching it with regexes
1747 and so on.
1642 1748
1643 Anything else is unsafe and will, at best, result in memory leaks. 1749 Anything else is unsafe and will, at best, result in memory leaks.
1644 1750
1645 The memory map associated with the $scalar is automatically removed 1751 The memory map associated with the $scalar is automatically removed
1646 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1752 when the $scalar is undef'd or destroyed, or when the
1647 "IO::AIO::munmap" functions are called. 1753 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1648 1754
1649 This calls the "mmap"(2) function internally. See your system's 1755 This calls the "mmap"(2) function internally. See your system's
1650 manual page for details on the $length, $prot and $flags parameters. 1756 manual page for details on the $length, $prot and $flags parameters.
1651 1757
1652 The $length must be larger than zero and smaller than the actual 1758 The $length must be larger than zero and smaller than the actual
… …
1685 my $fast_md5 = md5 $data; 1791 my $fast_md5 = md5 $data;
1686 1792
1687 IO::AIO::munmap $scalar 1793 IO::AIO::munmap $scalar
1688 Removes a previous mmap and undefines the $scalar. 1794 Removes a previous mmap and undefines the $scalar.
1689 1795
1796 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1797 $new_address = 0]
1798 Calls the Linux-specific mremap(2) system call. The $scalar must
1799 have been mapped by "IO::AIO::mmap", and $flags must currently
1800 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1801
1802 Returns true if successful, and false otherwise. If the underlying
1803 mmapped region has changed address, then the true value has the
1804 numerical value 1, otherwise it has the numerical value 0:
1805
1806 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1807 or die "mremap: $!";
1808
1809 if ($success*1) {
1810 warn "scalar has chanegd address in memory\n";
1811 }
1812
1813 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1814 implemented, but not supported and might go away in a future
1815 version.
1816
1817 On systems where this call is not supported or is not emulated, this
1818 call returns falls and sets $! to "ENOSYS".
1819
1690 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1820 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1691 Calls the "munlock" function, undoing the effects of a previous 1821 Calls the "munlock" function, undoing the effects of a previous
1692 "aio_mlock" call (see its description for details). 1822 "aio_mlock" call (see its description for details).
1693 1823
1694 IO::AIO::munlockall 1824 IO::AIO::munlockall
… …
1738 1868
1739 Please refer to pipe2(2) for more info on the $flags, but at the 1869 Please refer to pipe2(2) for more info on the $flags, but at the
1740 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" 1870 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1741 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were 1871 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1742 supported. 1872 supported.
1873
1874 Example: create a pipe race-free w.r.t. threads and fork:
1875
1876 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1877 or die "pipe2: $!\n";
1878
1879 $fh = IO::AIO::eventfd [$initval, [$flags]]
1880 This is a direct interface to the Linux eventfd(2) system call. The
1881 (unhelpful) defaults for $initval and $flags are 0 for both.
1882
1883 On success, the new eventfd filehandle is returned, otherwise
1884 returns "undef". If the eventfd syscall is missing, fails with
1885 "ENOSYS".
1886
1887 Please refer to eventfd(2) for more info on this call.
1888
1889 The following symbol flag values are available:
1890 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1891 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1892
1893 Example: create a new eventfd filehandle:
1894
1895 $fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
1896 or die "eventfd: $!\n";
1897
1898 $fh = IO::AIO::timerfd_create $clockid[, $flags]
1899 This is a direct interface to the Linux timerfd_create(2) system
1900 call. The (unhelpful) default for $flags is 0.
1901
1902 On success, the new timerfd filehandle is returned, otherwise
1903 returns "undef". If the eventfd syscall is missing, fails with
1904 "ENOSYS".
1905
1906 Please refer to timerfd_create(2) for more info on this call.
1907
1908 The following $clockid values are available:
1909 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
1910 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
1911 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
1912 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
1913
1914 The following $flags values are available (Linux 2.6.27):
1915 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
1916
1917 Example: create a new timerfd and set it to one-second repeated
1918 alarms, then wait for two alarms:
1919
1920 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
1921 or die "timerfd_create: $!\n";
1922
1923 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
1924 or die "timerfd_settime: $!\n";
1925
1926 for (1..2) {
1927 8 == sysread $fh, my $buf, 8
1928 or die "timerfd read failure\n";
1929
1930 printf "number of expirations (likely 1): %d\n",
1931 unpack "Q", $buf;
1932 }
1933
1934 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
1935 $new_interval, $nbw_value
1936 This is a direct interface to the Linux timerfd_settime(2) system
1937 call. Please refer to its manpage for more info on this call.
1938
1939 The new itimerspec is specified using two (possibly fractional)
1940 second values, $new_interval and $new_value).
1941
1942 On success, the current interval and value are returned (as per
1943 "timerfd_gettime"). On failure, the empty list is returned.
1944
1945 The following $flags values are available:
1946 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
1947
1948 See "IO::AIO::timerfd_create" for a full example.
1949
1950 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
1951 This is a direct interface to the Linux timerfd_gettime(2) system
1952 call. Please refer to its manpage for more info on this call.
1953
1954 On success, returns the current values of interval and value for the
1955 given timerfd (as potentially fractional second values). On failure,
1956 the empty list is returned.
1743 1957
1744EVENT LOOP INTEGRATION 1958EVENT LOOP INTEGRATION
1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1959 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1746 automatically into many event loops: 1960 automatically into many event loops:
1747 1961
… …
1797 forking, if "IO::AIO" was used in the parent. Calling it while 2011 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. 2012 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) 2013 Calling it at any time will also result in any undefined (by POSIX)
1800 behaviour. 2014 behaviour.
1801 2015
2016 LINUX-SPECIFIC CALLS
2017 When a call is documented as "linux-specific" then this means it
2018 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2019 availability and compatibility of such calls regardless of the platform
2020 it is compiled on, so platforms such as FreeBSD which often implement
2021 these calls will work. When in doubt, call them and see if they fail wth
2022 "ENOSYS".
2023
1802 MEMORY USAGE 2024 MEMORY USAGE
1803 Per-request usage: 2025 Per-request usage:
1804 2026
1805 Each aio request uses - depending on your architecture - around 100-200 2027 Each aio request uses - depending on your architecture - around 100-200
1806 bytes of memory. In addition, stat requests need a stat buffer (possibly 2028 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1816 In the execution phase, some aio requests require more memory for 2038 In the execution phase, some aio requests require more memory for
1817 temporary buffers, and each thread requires a stack and other data 2039 temporary buffers, and each thread requires a stack and other data
1818 structures (usually around 16k-128k, depending on the OS). 2040 structures (usually around 16k-128k, depending on the OS).
1819 2041
1820KNOWN BUGS 2042KNOWN BUGS
1821 Known bugs will be fixed in the next release. 2043 Known bugs will be fixed in the next release :)
2044
2045KNOWN ISSUES
2046 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2047 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2048 non-created hash slots or other scalars I didn't think of. It's best to
2049 avoid such and either use scalar variables or making sure that the
2050 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2051
2052 I am not sure anything can be done about this, so this is considered a
2053 known issue, rather than a bug.
1822 2054
1823SEE ALSO 2055SEE ALSO
1824 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2056 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1825 more natural syntax. 2057 more natural syntax.
1826 2058

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