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Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC vs.
Revision 1.65 by root, Fri Dec 4 01:19:58 2020 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
… …
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 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
221 230
222 IO::AIO::sendfile $ofh, $ifh, $offset, $count 231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
223 IO::AIO::fadvise $fh, $offset, $len, $advice 232 IO::AIO::fadvise $fh, $offset, $len, $advice
233
224 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 234 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
225 IO::AIO::munmap $scalar 235 IO::AIO::munmap $scalar
236 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
226 IO::AIO::madvise $scalar, $offset, $length, $advice 237 IO::AIO::madvise $scalar, $offset, $length, $advice
227 IO::AIO::mprotect $scalar, $offset, $length, $protect 238 IO::AIO::mprotect $scalar, $offset, $length, $protect
228 IO::AIO::munlock $scalar, $offset = 0, $length = undef 239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
229 IO::AIO::munlockall 240 IO::AIO::munlockall
241
242 # stat extensions
243 $counter = IO::AIO::st_gen
244 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
245 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
246 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
247 $seconds = IO::AIO::st_btimesec
248 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
249
250 # very much unportable syscalls
251 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
252 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
253 IO::AIO::tee $r_fh, $w_fh, $length, $flags
254 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
255 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
256 $fh = IO::AIO::memfd_create $pathname[, $flags]
257 $fh = IO::AIO::eventfd [$initval, [$flags]]
258 $fh = IO::AIO::timerfd_create $clockid[, $flags]
259 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
260 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
230 261
231 API NOTES 262 API NOTES
232 All the "aio_*" calls are more or less thin wrappers around the syscall 263 All the "aio_*" calls are more or less thin wrappers around the syscall
233 with the same name (sans "aio_"). The arguments are similar or 264 with the same name (sans "aio_"). The arguments are similar or
234 identical, and they all accept an additional (and optional) $callback 265 identical, and they all accept an additional (and optional) $callback
… …
332 "O_APPEND"), the following POSIX and non-POSIX constants are 363 "O_APPEND"), the following POSIX and non-POSIX constants are
333 available (missing ones on your system are, as usual, 0): 364 available (missing ones on your system are, as usual, 0):
334 365
335 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 366 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
336 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 367 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
337 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and 368 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
338 "O_TTY_INIT". 369 and "O_ACCMODE".
339 370
340 aio_close $fh, $callback->($status) 371 aio_close $fh, $callback->($status)
341 Asynchronously close a file and call the callback with the result 372 Asynchronously close a file and call the callback with the result
342 code. 373 code.
343 374
… …
373 404
374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 406 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
376 Reads or writes $length bytes from or to the specified $fh and 407 Reads or writes $length bytes from or to the specified $fh and
377 $offset into the scalar given by $data and offset $dataoffset and 408 $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 409 calls the callback with the actual number of bytes transferred (or
379 error, just like the syscall). 410 -1 on error, just like the syscall).
380 411
381 "aio_read" will, like "sysread", shrink or grow the $data scalar to 412 "aio_read" will, like "sysread", shrink or grow the $data scalar to
382 offset plus the actual number of bytes read. 413 offset plus the actual number of bytes read.
383 414
384 If $offset is undefined, then the current file descriptor offset 415 If $offset is undefined, then the current file descriptor offset
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441 As native sendfile syscalls (as practically any non-POSIX interface 472 As native sendfile syscalls (as practically any non-POSIX interface
442 hacked together in a hurry to improve benchmark numbers) tend to be 473 hacked together in a hurry to improve benchmark numbers) tend to be
443 rather buggy on many systems, this implementation tries to work 474 rather buggy on many systems, this implementation tries to work
444 around some known bugs in Linux and FreeBSD kernels (probably 475 around some known bugs in Linux and FreeBSD kernels (probably
445 others, too), but that might fail, so you really really should check 476 others, too), but that might fail, so you really really should check
446 the return value of "aio_sendfile" - fewre bytes than expected might 477 the return value of "aio_sendfile" - fewer bytes than expected might
447 have been transferred. 478 have been transferred.
448 479
449 aio_readahead $fh,$offset,$length, $callback->($retval) 480 aio_readahead $fh,$offset,$length, $callback->($retval)
450 "aio_readahead" populates the page cache with data from a file so 481 "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 482 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 486 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 487 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 488 read beyond the end of the file. The current file offset of the file
458 is left unchanged. 489 is left unchanged.
459 490
460 If that syscall doesn't exist (likely if your OS isn't Linux) it 491 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 492 will be emulated by simply reading the data, which would have a
462 similar effect. 493 similar effect.
463 494
464 aio_stat $fh_or_path, $callback->($status) 495 aio_stat $fh_or_path, $callback->($status)
465 aio_lstat $fh, $callback->($status) 496 aio_lstat $fh, $callback->($status)
466 Works like perl's "stat" or "lstat" in void context. The callback 497 Works almost exactly like perl's "stat" or "lstat" in void context.
467 will be called after the stat and the results will be available 498 The callback will be called after the stat and the results will be
468 using "stat _" or "-s _" etc... 499 available using "stat _" or "-s _" and other tests (with the
500 exception of "-B" and "-T").
469 501
470 The pathname passed to "aio_stat" must be absolute. See API NOTES, 502 The pathname passed to "aio_stat" must be absolute. See API NOTES,
471 above, for an explanation. 503 above, for an explanation.
472 504
473 Currently, the stats are always 64-bit-stats, i.e. instead of 505 Currently, the stats are always 64-bit-stats, i.e. instead of
… …
481 back on traditional behaviour). 513 back on traditional behaviour).
482 514
483 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 515 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
484 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 516 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
485 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 517 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
518
519 To access higher resolution stat timestamps, see "SUBSECOND STAT
520 TIME ACCESS".
486 521
487 Example: Print the length of /etc/passwd: 522 Example: Print the length of /etc/passwd:
488 523
489 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
490 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
… …
532 namemax => 255, 567 namemax => 255,
533 frsize => 1024, 568 frsize => 1024,
534 fsid => 1810 569 fsid => 1810
535 } 570 }
536 571
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) 572 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
623 Works like perl's "utime" function (including the special case of 573 Works like perl's "utime" function (including the special case of
624 $atime and $mtime being undef). Fractional times are supported if 574 $atime and $mtime being undef). Fractional times are supported if
625 the underlying syscalls support them. 575 the underlying syscalls support them.
626 576
627 When called with a pathname, uses utimes(2) if available, otherwise 577 When called with a pathname, uses utimensat(2) or utimes(2) if
628 utime(2). If called on a file descriptor, uses futimes(2) if 578 available, otherwise utime(2). If called on a file descriptor, uses
629 available, otherwise returns ENOSYS, so this is not portable. 579 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
580 this is not portable.
630 581
631 Examples: 582 Examples:
632 583
633 # set atime and mtime to current time (basically touch(1)): 584 # set atime and mtime to current time (basically touch(1)):
634 aio_utime "path", undef, undef; 585 aio_utime "path", undef, undef;
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657 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate 608 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
658 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 609 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
659 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 610 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
660 611
661 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range 612 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 613 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
614 "FALLOC_FL_INSERT_RANGE" to insert a range and
615 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
663 (see your fallocate(2) manpage). 616 fallocate(2) manpage).
664 617
665 The file system block size used by "fallocate" is presumably the 618 The file system block size used by "fallocate" is presumably the
666 "f_bsize" returned by "statvfs". 619 "f_bsize" returned by "statvfs", but different filesystems and
620 filetypes can dictate other limitations.
667 621
668 If "fallocate" isn't available or cannot be emulated (currently no 622 If "fallocate" isn't available or cannot be emulated (currently no
669 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 623 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
670 624
671 aio_chmod $fh_or_path, $mode, $callback->($status) 625 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
715 669
716 On systems that support the AIO::WD working directory abstraction 670 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased - 671 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd. 672 instead of failing, "rename" is called on the absolute path of $wd.
719 673
674 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
675 Basically a version of "aio_rename" with an additional $flags
676 argument. Calling this with "$flags=0" is the same as calling
677 "aio_rename".
678
679 Non-zero flags are currently only supported on GNU/Linux systems
680 that support renameat2. Other systems fail with "ENOSYS" in this
681 case.
682
683 The following constants are available (missing ones are, as usual
684 0), see renameat2(2) for details:
685
686 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
687 "IO::AIO::RENAME_WHITEOUT".
688
720 aio_mkdir $pathname, $mode, $callback->($status) 689 aio_mkdir $pathname, $mode, $callback->($status)
721 Asynchronously mkdir (create) a directory and call the callback with 690 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 691 the result code. $mode will be modified by the umask at the time the
723 request is executed, so do not change your umask. 692 request is executed, so do not change your umask.
724 693
… …
746 The flags are a combination of the following constants, ORed 715 The flags are a combination of the following constants, ORed
747 together (the flags will also be passed to the callback, possibly 716 together (the flags will also be passed to the callback, possibly
748 modified): 717 modified):
749 718
750 IO::AIO::READDIR_DENTS 719 IO::AIO::READDIR_DENTS
751 When this flag is off, then the callback gets an arrayref 720 Normally the callback gets an arrayref consisting of names only
752 consisting of names only (as with "aio_readdir"), otherwise it 721 (as with "aio_readdir"). If this flag is set, then the callback
753 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 722 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
754 describing a single directory entry in more detail. 723 describing a single directory entry in more detail:
755 724
756 $name is the name of the entry. 725 $name is the name of the entry.
757 726
758 $type is one of the "IO::AIO::DT_xxx" constants: 727 $type is one of the "IO::AIO::DT_xxx" constants:
759 728
760 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 729 "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", 730 "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". 731 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
763 732
764 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 733 "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 734 you need to know, you have to run stat yourself. Also, for
766 reasons, the $type scalars are read-only: you can not modify 735 speed/memory reasons, the $type scalars are read-only: you must
767 them. 736 not modify them.
768 737
769 $inode is the inode number (which might not be exact on systems 738 $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 739 with 64 bit inode numbers and 32 bit perls). This field has
771 unspecified content on systems that do not deliver the inode 740 unspecified content on systems that do not deliver the inode
772 information. 741 information.
… …
784 of which names with short names are tried first. 753 of which names with short names are tried first.
785 754
786 IO::AIO::READDIR_STAT_ORDER 755 IO::AIO::READDIR_STAT_ORDER
787 When this flag is set, then the names will be returned in an 756 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 757 order suitable for stat()'ing each one. That is, when you plan
789 to stat() all files in the given directory, then the returned 758 to stat() most or all files in the given directory, then the
790 order will likely be fastest. 759 returned order will likely be faster.
791 760
792 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 761 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
793 specified, then the likely dirs come first, resulting in a less 762 specified, then the likely dirs come first, resulting in a less
794 optimal stat order. 763 optimal stat order for stat'ing all entries, but likely a more
764 optimal order for finding subdirectories.
795 765
796 IO::AIO::READDIR_FOUND_UNKNOWN 766 IO::AIO::READDIR_FOUND_UNKNOWN
797 This flag should not be set when calling "aio_readdirx". 767 This flag should not be set when calling "aio_readdirx".
798 Instead, it is being set by "aio_readdirx", when any of the 768 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 769 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
800 flag therefore indicates that all $type's are known, which can 770 flag therefore indicates that all $type's are known, which can
801 be used to speed up some algorithms. 771 be used to speed up some algorithms.
802 772
773 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
774 Opens, reads and closes the given file. The data is put into $data,
775 which is resized as required.
776
777 If $offset is negative, then it is counted from the end of the file.
778
779 If $length is zero, then the remaining length of the file is used.
780 Also, in this case, the same limitations to modifying $data apply as
781 when IO::AIO::mmap is used, i.e. it must only be modified in-place
782 with "substr". If the size of the file is known, specifying a
783 non-zero $length results in a performance advantage.
784
785 This request is similar to the older "aio_load" request, but since
786 it is a single request, it might be more efficient to use.
787
788 Example: load /etc/passwd into $passwd.
789
790 my $passwd;
791 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
792 $_[0] >= 0
793 or die "/etc/passwd: $!\n";
794
795 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
796 print $passwd;
797 };
798 IO::AIO::flush;
799
803 aio_load $pathname, $data, $callback->($status) 800 aio_load $pathname, $data, $callback->($status)
804 This is a composite request that tries to fully load the given file 801 This is a composite request that tries to fully load the given file
805 into memory. Status is the same as with aio_read. 802 into memory. Status is the same as with aio_read.
803
804 Using "aio_slurp" might be more efficient, as it is a single
805 request.
806 806
807 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
808 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
809 or destination) from $srcpath to $dstpath and call the callback with 809 or destination) from $srcpath to $dstpath and call the callback with
810 a status of 0 (ok) or -1 (error, see $!). 810 a status of 0 (ok) or -1 (error, see $!).
811
812 Existing destination files will be truncated.
811 813
812 This is a composite request that creates the destination file with 814 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 815 mode 0200 and copies the contents of the source file into it using
814 "aio_sendfile", followed by restoring atime, mtime, access mode and 816 "aio_sendfile", followed by restoring atime, mtime, access mode and
815 uid/gid, in that order. 817 uid/gid, in that order.
… …
832 to efficiently separate the entries of directory $path into two sets 834 to efficiently separate the entries of directory $path into two sets
833 of names, directories you can recurse into (directories), and ones 835 of names, directories you can recurse into (directories), and ones
834 you cannot recurse into (everything else, including symlinks to 836 you cannot recurse into (everything else, including symlinks to
835 directories). 837 directories).
836 838
837 "aio_scandir" is a composite request that creates of many sub 839 "aio_scandir" is a composite request that generates many sub
838 requests_ $maxreq specifies the maximum number of outstanding aio 840 requests. $maxreq specifies the maximum number of outstanding aio
839 requests that this function generates. If it is "<= 0", then a 841 requests that this function generates. If it is "<= 0", then a
840 suitable default will be chosen (currently 4). 842 suitable default will be chosen (currently 4).
841 843
842 On error, the callback is called without arguments, otherwise it 844 On error, the callback is called without arguments, otherwise it
843 receives two array-refs with path-relative entry names. 845 receives two array-refs with path-relative entry names.
… …
908 So in general, you should only use these calls for things that do 910 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 911 (filesystem) I/O, not for things that wait for other events
910 (network, other processes), although if you are careful and know 912 (network, other processes), although if you are careful and know
911 what you are doing, you still can. 913 what you are doing, you still can.
912 914
915 The following constants are available and can be used for normal
916 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
917
918 "F_DUPFD_CLOEXEC",
919
920 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
921
922 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
923 "FIDEDUPERANGE".
924
925 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
926 "F_SEAL_GROW" and "F_SEAL_WRITE".
927
928 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
929 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
930
931 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
932 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
933 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
934
935 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
936 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
937 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
938 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
939 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
940
941 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
942 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
943 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
944 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
945 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
946 "FS_XFLAG_HASATTR",
947
913 aio_sync $callback->($status) 948 aio_sync $callback->($status)
914 Asynchronously call sync and call the callback when finished. 949 Asynchronously call sync and call the callback when finished.
915 950
916 aio_fsync $fh, $callback->($status) 951 aio_fsync $fh, $callback->($status)
917 Asynchronously call fsync on the given filehandle and call the 952 Asynchronously call fsync on the given filehandle and call the
… …
953 Future versions of this function might fall back to other methods 988 Future versions of this function might fall back to other methods
954 when "fsync" on the directory fails (such as calling "sync"). 989 when "fsync" on the directory fails (such as calling "sync").
955 990
956 Passes 0 when everything went ok, and -1 on error. 991 Passes 0 when everything went ok, and -1 on error.
957 992
958 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 993 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
959 $callback->($status) 994 $callback->($status)
960 This is a rather advanced IO::AIO call, which only works on 995 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 996 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, 997 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 998 note that the scalar must only be modified in-place while an aio
… …
965 1000
966 It calls the "msync" function of your OS, if available, with the 1001 It calls the "msync" function of your OS, if available, with the
967 memory area starting at $offset in the string and ending $length 1002 memory area starting at $offset in the string and ending $length
968 bytes later. If $length is negative, counts from the end, and if 1003 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 1004 $length is "undef", then it goes till the end of the string. The
970 flags can be a combination of "IO::AIO::MS_ASYNC", 1005 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
971 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 1006 an optional "IO::AIO::MS_INVALIDATE".
972 1007
973 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 1008 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
974 $callback->($status) 1009 $callback->($status)
975 This is a rather advanced IO::AIO call, which works best on 1010 This is a rather advanced IO::AIO call, which works best on
976 mmap(2)ed scalars. 1011 mmap(2)ed scalars.
… …
1007 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1042 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1008 aio_mlock $data; # mlock in background 1043 aio_mlock $data; # mlock in background
1009 1044
1010 aio_mlockall $flags, $callback->($status) 1045 aio_mlockall $flags, $callback->($status)
1011 Calls the "mlockall" function with the given $flags (a combination 1046 Calls the "mlockall" function with the given $flags (a combination
1012 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). 1047 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1048 "IO::AIO::MCL_ONFAULT").
1013 1049
1014 On systems that do not implement "mlockall", this function returns 1050 On systems that do not implement "mlockall", this function returns
1015 -1 and sets errno to "ENOSYS". 1051 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1052 supported by the system result in a return value of -1 with errno
1053 being set to "EINVAL".
1016 1054
1017 Note that the corresponding "munlockall" is synchronous and is 1055 Note that the corresponding "munlockall" is synchronous and is
1018 documented under "MISCELLANEOUS FUNCTIONS". 1056 documented under "MISCELLANEOUS FUNCTIONS".
1019 1057
1020 Example: asynchronously lock all current and future pages into 1058 Example: asynchronously lock all current and future pages into
… …
1062 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1100 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1063 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1101 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1064 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1102 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1065 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1103 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1066 1104
1067 At the time of this writing (Linux 3.2), this requets is unreliable 1105 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 1106 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 1107 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 1108 large number of extents. The code (only) works around all these
1071 is undef. 1109 issues if $count is "undef".
1072 1110
1073 aio_group $callback->(...) 1111 aio_group $callback->(...)
1074 This is a very special aio request: Instead of doing something, it 1112 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 1113 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 1114 to bundle many requests into a single, composite, request with a
… …
1185 There are some caveats: when directories get renamed (or deleted), the 1223 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 1224 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, 1225 nowhere at all), while the directory fd, if available on the system,
1188 will still point to the original directory. Most functions accepting a 1226 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 1227 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 1228 older systems. Some functions (such as "aio_realpath") will always rely
1191 string form of the pathname. 1229 on the string form of the pathname.
1192 1230
1193 So this functionality is mainly useful to get some protection against 1231 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 1232 "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 1233 future reference, and to speed up doing many operations in the same
1196 directory (e.g. when stat'ing all files in a directory). 1234 directory (e.g. when stat'ing all files in a directory).
… …
1209 fails the request with "ENOENT", there is often no need for error 1247 fails the request with "ENOENT", there is often no need for error
1210 checking in the "aio_wd" callback, as future requests using the 1248 checking in the "aio_wd" callback, as future requests using the
1211 value will fail in the expected way. 1249 value will fail in the expected way.
1212 1250
1213 IO::AIO::CWD 1251 IO::AIO::CWD
1214 This is a compiletime constant (object) that represents the process 1252 This is a compile time constant (object) that represents the process
1215 current working directory. 1253 current working directory.
1216 1254
1217 Specifying this object as working directory object for a pathname is 1255 Specifying this object as working directory object for a pathname is
1218 as if the pathname would be specified directly, without a directory 1256 as if the pathname would be specified directly, without a directory
1219 object. For example, these calls are functionally identical: 1257 object. For example, these calls are functionally identical:
… …
1444 Strictly equivalent to: 1482 Strictly equivalent to:
1445 1483
1446 IO::AIO::poll_wait, IO::AIO::poll_cb 1484 IO::AIO::poll_wait, IO::AIO::poll_cb
1447 while IO::AIO::nreqs; 1485 while IO::AIO::nreqs;
1448 1486
1487 This function can be useful at program aborts, to make sure
1488 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1489 already calls this function on normal exits), or when you are merely
1490 using "IO::AIO" for its more advanced functions, rather than for
1491 async I/O, e.g.:
1492
1493 my ($dirs, $nondirs);
1494 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1495 IO::AIO::flush;
1496 # $dirs, $nondirs are now set
1497
1449 IO::AIO::max_poll_reqs $nreqs 1498 IO::AIO::max_poll_reqs $nreqs
1450 IO::AIO::max_poll_time $seconds 1499 IO::AIO::max_poll_time $seconds
1451 These set the maximum number of requests (default 0, meaning 1500 These set the maximum number of requests (default 0, meaning
1452 infinity) that are being processed by "IO::AIO::poll_cb" in one 1501 infinity) that are being processed by "IO::AIO::poll_cb" in one
1453 call, respectively the maximum amount of time (default 0, meaning 1502 call, respectively the maximum amount of time (default 0, meaning
… …
1547 This is a very bad function to use in interactive programs because 1596 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 1597 it blocks, and a bad way to reduce concurrency because it is
1549 inexact: Better use an "aio_group" together with a feed callback. 1598 inexact: Better use an "aio_group" together with a feed callback.
1550 1599
1551 Its main use is in scripts without an event loop - when you want to 1600 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: 1601 stat a lot of files, you can write something like this:
1553 1602
1554 IO::AIO::max_outstanding 32; 1603 IO::AIO::max_outstanding 32;
1555 1604
1556 for my $path (...) { 1605 for my $path (...) {
1557 aio_stat $path , ...; 1606 aio_stat $path , ...;
… …
1586 1635
1587 IO::AIO::npending 1636 IO::AIO::npending
1588 Returns the number of requests currently in the pending state 1637 Returns the number of requests currently in the pending state
1589 (executed, but not yet processed by poll_cb). 1638 (executed, but not yet processed by poll_cb).
1590 1639
1640 SUBSECOND STAT TIME ACCESS
1641 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1642 generally find access/modification and change times with subsecond time
1643 accuracy of the system supports it, but perl's built-in functions only
1644 return the integer part.
1645
1646 The following functions return the timestamps of the most recent stat
1647 with subsecond precision on most systems and work both after
1648 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1649 value is only meaningful after a successful "stat"/"lstat" call, or
1650 during/after a successful "aio_stat"/"aio_lstat" callback.
1651
1652 This is similar to the Time::HiRes "stat" functions, but can return full
1653 resolution without rounding and work with standard perl "stat",
1654 alleviating the need to call the special "Time::HiRes" functions, which
1655 do not act like their perl counterparts.
1656
1657 On operating systems or file systems where subsecond time resolution is
1658 not supported or could not be detected, a fractional part of 0 is
1659 returned, so it is always safe to call these functions.
1660
1661 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1662 IO::AIO::st_btime
1663 Return the access, modication, change or birth time, respectively,
1664 including fractional part. Due to the limited precision of floating
1665 point, the accuracy on most platforms is only a bit better than
1666 milliseconds for times around now - see the *nsec* function family,
1667 below, for full accuracy.
1668
1669 File birth time is only available when the OS and perl support it
1670 (on FreeBSD and NetBSD at the time of this writing, although support
1671 is adaptive, so if your OS/perl gains support, IO::AIO can take
1672 advantage of it). On systems where it isn't available, 0 is
1673 currently returned, but this might change to "undef" in a future
1674 version.
1675
1676 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1677 Returns access, modification, change and birth time all in one go,
1678 and maybe more times in the future version.
1679
1680 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1681 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1682 Return the fractional access, modifcation, change or birth time, in
1683 nanoseconds, as an integer in the range 0 to 999999999.
1684
1685 Note that no accessors are provided for access, modification and
1686 change times - you need to get those from "stat _" if required ("int
1687 IO::AIO::st_atime" and so on will *not* generally give you the
1688 correct value).
1689
1690 $seconds = IO::AIO::st_btimesec
1691 The (integral) seconds part of the file birth time, if available.
1692
1693 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1694 Like the functions above, but returns all four times in one go (and
1695 maybe more in future versions).
1696
1697 $counter = IO::AIO::st_gen
1698 Returns the generation counter (in practice this is just a random
1699 number) of the file. This is only available on platforms which have
1700 this member in their "struct stat" (most BSDs at the time of this
1701 writing) and generally only to the root usert. If unsupported, 0 is
1702 returned, but this might change to "undef" in a future version.
1703
1704 Example: print the high resolution modification time of /etc, using
1705 "stat", and "IO::AIO::aio_stat".
1706
1707 if (stat "/etc") {
1708 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1709 }
1710
1711 IO::AIO::aio_stat "/etc", sub {
1712 $_[0]
1713 and return;
1714
1715 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1716 };
1717
1718 IO::AIO::flush;
1719
1720 Output of the awbove on my system, showing reduced and full accuracy:
1721
1722 stat(/etc) mtime: 1534043702.020808
1723 aio_stat(/etc) mtime: 1534043702.020807792
1724
1591 MISCELLANEOUS FUNCTIONS 1725 MISCELLANEOUS FUNCTIONS
1592 IO::AIO implements some functions that are useful when you want to use 1726 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 1727 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_*" 1728 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1595 counterpart. 1729 counterpart.
1730
1731 $numfd = IO::AIO::get_fdlimit
1732 Tries to find the current file descriptor limit and returns it, or
1733 "undef" and sets $! in case of an error. The limit is one larger
1734 than the highest valid file descriptor number.
1735
1736 IO::AIO::min_fdlimit [$numfd]
1737 Try to increase the current file descriptor limit(s) to at least
1738 $numfd by changing the soft or hard file descriptor resource limit.
1739 If $numfd is missing, it will try to set a very high limit, although
1740 this is not recommended when you know the actual minimum that you
1741 require.
1742
1743 If the limit cannot be raised enough, the function makes a
1744 best-effort attempt to increase the limit as much as possible, using
1745 various tricks, while still failing. You can query the resulting
1746 limit using "IO::AIO::get_fdlimit".
1747
1748 If an error occurs, returns "undef" and sets $!, otherwise returns
1749 true.
1596 1750
1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1598 Calls the "eio_sendfile_sync" function, which is like 1752 Calls the "eio_sendfile_sync" function, which is like
1599 "aio_sendfile", but is blocking (this makes most sense if you know 1753 "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 1754 the input data is likely cached already and the output filehandle is
… …
1617 details). The following advice constants are available: 1771 details). The following advice constants are available:
1618 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1619 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1620 "IO::AIO::MADV_DONTNEED". 1774 "IO::AIO::MADV_DONTNEED".
1621 1775
1776 If $offset is negative, counts from the end. If $length is negative,
1777 the remaining length of the $scalar is used. If possible, $length
1778 will be reduced to fit into the $scalar.
1779
1622 On systems that do not implement "posix_madvise", this function 1780 On systems that do not implement "posix_madvise", this function
1623 returns ENOSYS, otherwise the return value of "posix_madvise". 1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1624 1782
1625 IO::AIO::mprotect $scalar, $offset, $len, $protect 1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1626 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1627 $scalar (see its manpage for details). The following protect 1785 $scalar (see its manpage for details). The following protect
1628 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1629 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1787 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1630 1788
1789 If $offset is negative, counts from the end. If $length is negative,
1790 the remaining length of the $scalar is used. If possible, $length
1791 will be reduced to fit into the $scalar.
1792
1631 On systems that do not implement "mprotect", this function returns 1793 On systems that do not implement "mprotect", this function returns
1632 ENOSYS, otherwise the return value of "mprotect". 1794 ENOSYS, otherwise the return value of "mprotect".
1633 1795
1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1635 Memory-maps a file (or anonymous memory range) and attaches it to 1797 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 1798 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise. 1799 on success, and false otherwise.
1638 1800
1801 The scalar must exist, but its contents do not matter - this means
1802 you cannot use a nonexistant array or hash element. When in doubt,
1803 "undef" the scalar first.
1804
1639 The only operations allowed on the scalar are "substr"/"vec" that 1805 The only operations allowed on the mmapped scalar are
1640 don't change the string length, and most read-only operations such 1806 "substr"/"vec", which don't change the string length, and most
1641 as copying it or searching it with regexes and so on. 1807 read-only operations such as copying it or searching it with regexes
1808 and so on.
1642 1809
1643 Anything else is unsafe and will, at best, result in memory leaks. 1810 Anything else is unsafe and will, at best, result in memory leaks.
1644 1811
1645 The memory map associated with the $scalar is automatically removed 1812 The memory map associated with the $scalar is automatically removed
1646 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1813 when the $scalar is undef'd or destroyed, or when the
1647 "IO::AIO::munmap" functions are called. 1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1648 1815
1649 This calls the "mmap"(2) function internally. See your system's 1816 This calls the "mmap"(2) function internally. See your system's
1650 manual page for details on the $length, $prot and $flags parameters. 1817 manual page for details on the $length, $prot and $flags parameters.
1651 1818
1652 The $length must be larger than zero and smaller than the actual 1819 The $length must be larger than zero and smaller than the actual
… …
1685 my $fast_md5 = md5 $data; 1852 my $fast_md5 = md5 $data;
1686 1853
1687 IO::AIO::munmap $scalar 1854 IO::AIO::munmap $scalar
1688 Removes a previous mmap and undefines the $scalar. 1855 Removes a previous mmap and undefines the $scalar.
1689 1856
1857 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1858 $new_address = 0]
1859 Calls the Linux-specific mremap(2) system call. The $scalar must
1860 have been mapped by "IO::AIO::mmap", and $flags must currently
1861 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1862
1863 Returns true if successful, and false otherwise. If the underlying
1864 mmapped region has changed address, then the true value has the
1865 numerical value 1, otherwise it has the numerical value 0:
1866
1867 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1868 or die "mremap: $!";
1869
1870 if ($success*1) {
1871 warn "scalar has chanegd address in memory\n";
1872 }
1873
1874 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1875 implemented, but not supported and might go away in a future
1876 version.
1877
1878 On systems where this call is not supported or is not emulated, this
1879 call returns falls and sets $! to "ENOSYS".
1880
1881 IO::AIO::mlockall $flags
1882 Calls the "eio_mlockall_sync" function, which is like
1883 "aio_mlockall", but is blocking.
1884
1690 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1885 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1691 Calls the "munlock" function, undoing the effects of a previous 1886 Calls the "munlock" function, undoing the effects of a previous
1692 "aio_mlock" call (see its description for details). 1887 "aio_mlock" call (see its description for details).
1693 1888
1694 IO::AIO::munlockall 1889 IO::AIO::munlockall
1695 Calls the "munlockall" function. 1890 Calls the "munlockall" function.
1696 1891
1697 On systems that do not implement "munlockall", this function returns 1892 On systems that do not implement "munlockall", this function returns
1698 ENOSYS, otherwise the return value of "munlockall". 1893 ENOSYS, otherwise the return value of "munlockall".
1894
1895 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1896 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1897 socket and return the new file handle on success, or sets $! and
1898 returns "undef" on error.
1899
1900 The remote name of the new socket will be stored in $sockaddr, which
1901 will be extended to allow for at least $sockaddr_maxlen octets. If
1902 the socket name does not fit into $sockaddr_maxlen octets, this is
1903 signaled by returning a longer string in $sockaddr, which might or
1904 might not be truncated.
1905
1906 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1907 $sockaddr_maxlen.
1908
1909 The main reasons to use this syscall rather than portable
1910 C«accept(2)> are that you can specify "SOCK_NONBLOCK" and/or
1911 "SOCK_CLOEXEC" flags and you can accept name-less sockets by
1912 specifying 0 for $sockaddr_maxlen, which is sadly not possible with
1913 perl's interface to "accept".
1699 1914
1700 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags 1915 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1701 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or 1916 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1702 $w_off are "undef", then "NULL" is passed for these, otherwise they 1917 $w_off are "undef", then "NULL" is passed for these, otherwise they
1703 should be the file offset. 1918 should be the file offset.
… …
1738 1953
1739 Please refer to pipe2(2) for more info on the $flags, but at the 1954 Please refer to pipe2(2) for more info on the $flags, but at the
1740 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" 1955 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1741 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were 1956 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1742 supported. 1957 supported.
1958
1959 Example: create a pipe race-free w.r.t. threads and fork:
1960
1961 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1962 or die "pipe2: $!\n";
1963
1964 $fh = IO::AIO::memfd_create $pathname[, $flags]
1965 This is a direct interface to the Linux memfd_create(2) system call.
1966 The (unhelpful) default for $flags is 0, but your default should be
1967 "IO::AIO::MFD_CLOEXEC".
1968
1969 On success, the new memfd filehandle is returned, otherwise returns
1970 "undef". If the memfd_create syscall is missing, fails with
1971 "ENOSYS".
1972
1973 Please refer to memfd_create(2) for more info on this call.
1974
1975 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1976 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1977
1978 Example: create a new memfd.
1979
1980 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1981 or die "m,emfd_create: $!\n";
1982 =item $fh = IO::AIO::eventfd [$initval, [$flags]]
1983
1984 This is a direct interface to the Linux eventfd(2) system call. The
1985 (unhelpful) defaults for $initval and $flags are 0 for both.
1986
1987 On success, the new eventfd filehandle is returned, otherwise
1988 returns "undef". If the eventfd syscall is missing, fails with
1989 "ENOSYS".
1990
1991 Please refer to eventfd(2) for more info on this call.
1992
1993 The following symbol flag values are available:
1994 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1995 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1996
1997 Example: create a new eventfd filehandle:
1998
1999 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2000 or die "eventfd: $!\n";
2001
2002 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2003 This is a direct interface to the Linux timerfd_create(2) system
2004 call. The (unhelpful) default for $flags is 0, but your default
2005 should be "IO::AIO::TFD_CLOEXEC".
2006
2007 On success, the new timerfd filehandle is returned, otherwise
2008 returns "undef". If the timerfd_create syscall is missing, fails
2009 with "ENOSYS".
2010
2011 Please refer to timerfd_create(2) for more info on this call.
2012
2013 The following $clockid values are available:
2014 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2015 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2016 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2017 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2018
2019 The following $flags values are available (Linux 2.6.27):
2020 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2021
2022 Example: create a new timerfd and set it to one-second repeated
2023 alarms, then wait for two alarms:
2024
2025 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2026 or die "timerfd_create: $!\n";
2027
2028 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2029 or die "timerfd_settime: $!\n";
2030
2031 for (1..2) {
2032 8 == sysread $fh, my $buf, 8
2033 or die "timerfd read failure\n";
2034
2035 printf "number of expirations (likely 1): %d\n",
2036 unpack "Q", $buf;
2037 }
2038
2039 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2040 $new_interval, $nbw_value
2041 This is a direct interface to the Linux timerfd_settime(2) system
2042 call. Please refer to its manpage for more info on this call.
2043
2044 The new itimerspec is specified using two (possibly fractional)
2045 second values, $new_interval and $new_value).
2046
2047 On success, the current interval and value are returned (as per
2048 "timerfd_gettime"). On failure, the empty list is returned.
2049
2050 The following $flags values are available:
2051 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2052
2053 See "IO::AIO::timerfd_create" for a full example.
2054
2055 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2056 This is a direct interface to the Linux timerfd_gettime(2) system
2057 call. Please refer to its manpage for more info on this call.
2058
2059 On success, returns the current values of interval and value for the
2060 given timerfd (as potentially fractional second values). On failure,
2061 the empty list is returned.
1743 2062
1744EVENT LOOP INTEGRATION 2063EVENT LOOP INTEGRATION
1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2064 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1746 automatically into many event loops: 2065 automatically into many event loops:
1747 2066
… …
1797 forking, if "IO::AIO" was used in the parent. Calling it while 2116 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. 2117 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) 2118 Calling it at any time will also result in any undefined (by POSIX)
1800 behaviour. 2119 behaviour.
1801 2120
2121 LINUX-SPECIFIC CALLS
2122 When a call is documented as "linux-specific" then this means it
2123 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2124 availability and compatibility of such calls regardless of the platform
2125 it is compiled on, so platforms such as FreeBSD which often implement
2126 these calls will work. When in doubt, call them and see if they fail wth
2127 "ENOSYS".
2128
1802 MEMORY USAGE 2129 MEMORY USAGE
1803 Per-request usage: 2130 Per-request usage:
1804 2131
1805 Each aio request uses - depending on your architecture - around 100-200 2132 Each aio request uses - depending on your architecture - around 100-200
1806 bytes of memory. In addition, stat requests need a stat buffer (possibly 2133 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1816 In the execution phase, some aio requests require more memory for 2143 In the execution phase, some aio requests require more memory for
1817 temporary buffers, and each thread requires a stack and other data 2144 temporary buffers, and each thread requires a stack and other data
1818 structures (usually around 16k-128k, depending on the OS). 2145 structures (usually around 16k-128k, depending on the OS).
1819 2146
1820KNOWN BUGS 2147KNOWN BUGS
1821 Known bugs will be fixed in the next release. 2148 Known bugs will be fixed in the next release :)
2149
2150KNOWN ISSUES
2151 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2152 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2153 non-created hash slots or other scalars I didn't think of. It's best to
2154 avoid such and either use scalar variables or making sure that the
2155 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2156
2157 I am not sure anything can be done about this, so this is considered a
2158 known issue, rather than a bug.
1822 2159
1823SEE ALSO 2160SEE ALSO
1824 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2161 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1825 more natural syntax. 2162 more natural syntax and IO::FDPass for file descriptor passing.
1826 2163
1827AUTHOR 2164AUTHOR
1828 Marc Lehmann <schmorp@schmorp.de> 2165 Marc Lehmann <schmorp@schmorp.de>
1829 http://home.schmorp.de/ 2166 http://home.schmorp.de/
1830 2167

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