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Revision 1.54 by root, Sun Jan 6 11:48:14 2013 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 {
… …
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 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*.
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.
64 68
65 EXAMPLE 69 EXAMPLE
66 This is a simple example that uses the EV module and loads /etc/passwd 70 This is a simple example that uses the EV module and loads /etc/passwd
67 asynchronously: 71 asynchronously:
68 72
69 use Fcntl;
70 use EV; 73 use EV;
71 use IO::AIO; 74 use IO::AIO;
72 75
73 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
… …
91 94
92 # file contents now in $contents 95 # file contents now in $contents
93 print $contents; 96 print $contents;
94 97
95 # exit event loop and program 98 # exit event loop and program
96 EV::unloop; 99 EV::break;
97 }; 100 };
98 }; 101 };
99 102
100 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 104 # check for sockets etc. etc.
102 105
103 # process events as long as there are some: 106 # process events as long as there are some:
104 EV::loop; 107 EV::run;
105 108
106REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
107 Every "aio_*" function creates a request. which is a C data structure 110 Every "aio_*" function creates a request. which is a C data structure
108 not directly visible to Perl. 111 not directly visible to Perl.
109 112
… …
172 aio_unlink $pathname, $callback->($status) 175 aio_unlink $pathname, $callback->($status)
173 aio_mknod $pathname, $mode, $dev, $callback->($status) 176 aio_mknod $pathname, $mode, $dev, $callback->($status)
174 aio_link $srcpath, $dstpath, $callback->($status) 177 aio_link $srcpath, $dstpath, $callback->($status)
175 aio_symlink $srcpath, $dstpath, $callback->($status) 178 aio_symlink $srcpath, $dstpath, $callback->($status)
176 aio_readlink $pathname, $callback->($link) 179 aio_readlink $pathname, $callback->($link)
177 aio_realpath $pathname, $callback->($link) 180 aio_realpath $pathname, $callback->($path)
178 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
179 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
180 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
181 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
182 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
183 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
… …
185 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
186 aio_load $pathname, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
187 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
188 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
189 aio_rmtree $pathname, $callback->($status) 193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
190 aio_sync $callback->($status) 196 aio_sync $callback->($status)
191 aio_syncfs $fh, $callback->($status) 197 aio_syncfs $fh, $callback->($status)
192 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
193 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
194 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
195 aio_pathsync $pathname, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
196 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
197 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
198 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
199 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
200 aio_group $callback->(...) 206 aio_group $callback->(...)
201 aio_nop $callback->() 207 aio_nop $callback->()
… …
215 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
216 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
217 IO::AIO::nreqs 223 IO::AIO::nreqs
218 IO::AIO::nready 224 IO::AIO::nready
219 IO::AIO::npending 225 IO::AIO::npending
226 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
227 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
220 228
221 IO::AIO::sendfile $ofh, $ifh, $offset, $count 229 IO::AIO::sendfile $ofh, $ifh, $offset, $count
222 IO::AIO::fadvise $fh, $offset, $len, $advice 230 IO::AIO::fadvise $fh, $offset, $len, $advice
223 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 231 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
224 IO::AIO::munmap $scalar 232 IO::AIO::munmap $scalar
233 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
225 IO::AIO::madvise $scalar, $offset, $length, $advice 234 IO::AIO::madvise $scalar, $offset, $length, $advice
226 IO::AIO::mprotect $scalar, $offset, $length, $protect 235 IO::AIO::mprotect $scalar, $offset, $length, $protect
227 IO::AIO::munlock $scalar, $offset = 0, $length = undef 236 IO::AIO::munlock $scalar, $offset = 0, $length = undef
228 IO::AIO::munlockall 237 IO::AIO::munlockall
229 238
… …
331 "O_APPEND"), the following POSIX and non-POSIX constants are 340 "O_APPEND"), the following POSIX and non-POSIX constants are
332 available (missing ones on your system are, as usual, 0): 341 available (missing ones on your system are, as usual, 0):
333 342
334 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 343 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
335 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 344 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
336 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". 345 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
346 and "O_ACCMODE".
337 347
338 aio_close $fh, $callback->($status) 348 aio_close $fh, $callback->($status)
339 Asynchronously close a file and call the callback with the result 349 Asynchronously close a file and call the callback with the result
340 code. 350 code.
341 351
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371 381
372 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
374 Reads or writes $length bytes from or to the specified $fh and 384 Reads or writes $length bytes from or to the specified $fh and
375 $offset into the scalar given by $data and offset $dataoffset and 385 $offset into the scalar given by $data and offset $dataoffset and
376 calls the callback without the actual number of bytes read (or -1 on 386 calls the callback with the actual number of bytes transferred (or
377 error, just like the syscall). 387 -1 on error, just like the syscall).
378 388
379 "aio_read" will, like "sysread", shrink or grow the $data scalar to 389 "aio_read" will, like "sysread", shrink or grow the $data scalar to
380 offset plus the actual number of bytes read. 390 offset plus the actual number of bytes read.
381 391
382 If $offset is undefined, then the current file descriptor offset 392 If $offset is undefined, then the current file descriptor offset
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439 As native sendfile syscalls (as practically any non-POSIX interface 449 As native sendfile syscalls (as practically any non-POSIX interface
440 hacked together in a hurry to improve benchmark numbers) tend to be 450 hacked together in a hurry to improve benchmark numbers) tend to be
441 rather buggy on many systems, this implementation tries to work 451 rather buggy on many systems, this implementation tries to work
442 around some known bugs in Linux and FreeBSD kernels (probably 452 around some known bugs in Linux and FreeBSD kernels (probably
443 others, too), but that might fail, so you really really should check 453 others, too), but that might fail, so you really really should check
444 the return value of "aio_sendfile" - fewre bytes than expected might 454 the return value of "aio_sendfile" - fewer bytes than expected might
445 have been transferred. 455 have been transferred.
446 456
447 aio_readahead $fh,$offset,$length, $callback->($retval) 457 aio_readahead $fh,$offset,$length, $callback->($retval)
448 "aio_readahead" populates the page cache with data from a file so 458 "aio_readahead" populates the page cache with data from a file so
449 that subsequent reads from that file will not block on disk I/O. The 459 that subsequent reads from that file will not block on disk I/O. The
… …
453 to a page boundary and bytes are read up to the next page boundary 463 to a page boundary and bytes are read up to the next page boundary
454 greater than or equal to (off-set+length). "aio_readahead" does not 464 greater than or equal to (off-set+length). "aio_readahead" does not
455 read beyond the end of the file. The current file offset of the file 465 read beyond the end of the file. The current file offset of the file
456 is left unchanged. 466 is left unchanged.
457 467
458 If that syscall doesn't exist (likely if your OS isn't Linux) it 468 If that syscall doesn't exist (likely if your kernel isn't Linux) it
459 will be emulated by simply reading the data, which would have a 469 will be emulated by simply reading the data, which would have a
460 similar effect. 470 similar effect.
461 471
462 aio_stat $fh_or_path, $callback->($status) 472 aio_stat $fh_or_path, $callback->($status)
463 aio_lstat $fh, $callback->($status) 473 aio_lstat $fh, $callback->($status)
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479 back on traditional behaviour). 489 back on traditional behaviour).
480 490
481 "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",
482 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 492 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
483 "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".
484 497
485 Example: Print the length of /etc/passwd: 498 Example: Print the length of /etc/passwd:
486 499
487 aio_stat "/etc/passwd", sub { 500 aio_stat "/etc/passwd", sub {
488 $_[0] and die "stat failed: $!"; 501 $_[0] and die "stat failed: $!";
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530 namemax => 255, 543 namemax => 255,
531 frsize => 1024, 544 frsize => 1024,
532 fsid => 1810 545 fsid => 1810
533 } 546 }
534 547
535 Here is a (likely partial) list of fsid values used by Linux - it is
536 safe to hardcode these when the $^O is "linux":
537
538 0x0000adf5 adfs
539 0x0000adff affs
540 0x5346414f afs
541 0x09041934 anon-inode filesystem
542 0x00000187 autofs
543 0x42465331 befs
544 0x1badface bfs
545 0x42494e4d binfmt_misc
546 0x9123683e btrfs
547 0x0027e0eb cgroupfs
548 0xff534d42 cifs
549 0x73757245 coda
550 0x012ff7b7 coh
551 0x28cd3d45 cramfs
552 0x453dcd28 cramfs-wend (wrong endianness)
553 0x64626720 debugfs
554 0x00001373 devfs
555 0x00001cd1 devpts
556 0x0000f15f ecryptfs
557 0x00414a53 efs
558 0x0000137d ext
559 0x0000ef53 ext2/ext3
560 0x0000ef51 ext2
561 0x00004006 fat
562 0x65735546 fuseblk
563 0x65735543 fusectl
564 0x0bad1dea futexfs
565 0x01161970 gfs2
566 0x47504653 gpfs
567 0x00004244 hfs
568 0xf995e849 hpfs
569 0x958458f6 hugetlbfs
570 0x2bad1dea inotifyfs
571 0x00009660 isofs
572 0x000072b6 jffs2
573 0x3153464a jfs
574 0x6b414653 k-afs
575 0x0bd00bd0 lustre
576 0x0000137f minix
577 0x0000138f minix 30 char names
578 0x00002468 minix v2
579 0x00002478 minix v2 30 char names
580 0x00004d5a minix v3
581 0x19800202 mqueue
582 0x00004d44 msdos
583 0x0000564c novell
584 0x00006969 nfs
585 0x6e667364 nfsd
586 0x00003434 nilfs
587 0x5346544e ntfs
588 0x00009fa1 openprom
589 0x7461636F ocfs2
590 0x00009fa0 proc
591 0x6165676c pstorefs
592 0x0000002f qnx4
593 0x858458f6 ramfs
594 0x52654973 reiserfs
595 0x00007275 romfs
596 0x67596969 rpc_pipefs
597 0x73636673 securityfs
598 0xf97cff8c selinux
599 0x0000517b smb
600 0x534f434b sockfs
601 0x73717368 squashfs
602 0x62656572 sysfs
603 0x012ff7b6 sysv2
604 0x012ff7b5 sysv4
605 0x01021994 tmpfs
606 0x15013346 udf
607 0x00011954 ufs
608 0x54190100 ufs byteswapped
609 0x00009fa2 usbdevfs
610 0x01021997 v9fs
611 0xa501fcf5 vxfs
612 0xabba1974 xenfs
613 0x012ff7b4 xenix
614 0x58465342 xfs
615 0x012fd16d xia
616
617 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 548 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
618 Works like perl's "utime" function (including the special case of 549 Works like perl's "utime" function (including the special case of
619 $atime and $mtime being undef). Fractional times are supported if 550 $atime and $mtime being undef). Fractional times are supported if
620 the underlying syscalls support them. 551 the underlying syscalls support them.
621 552
… …
644 575
645 aio_truncate $fh_or_path, $offset, $callback->($status) 576 aio_truncate $fh_or_path, $offset, $callback->($status)
646 Works like truncate(2) or ftruncate(2). 577 Works like truncate(2) or ftruncate(2).
647 578
648 aio_allocate $fh, $mode, $offset, $len, $callback->($status) 579 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
649 Allocates or freed disk space according to the $mode argument. See 580 Allocates or frees disk space according to the $mode argument. See
650 the linux "fallocate" docuemntation for details. 581 the linux "fallocate" documentation for details.
651 582
652 $mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to 583 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
653 allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 584 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
654 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 585 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
655 586
587 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove 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
591 fallocate(2) manpage).
592
656 The file system block size used by "fallocate" is presumably the 593 The file system block size used by "fallocate" is presumably the
657 "f_bsize" returned by "statvfs". 594 "f_bsize" returned by "statvfs", but different filesystems and
595 filetypes can dictate other limitations.
658 596
659 If "fallocate" isn't available or cannot be emulated (currently no 597 If "fallocate" isn't available or cannot be emulated (currently no
660 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 598 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
661 599
662 aio_chmod $fh_or_path, $mode, $callback->($status) 600 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
706 644
707 On systems that support the AIO::WD working directory abstraction 645 On systems that support the AIO::WD working directory abstraction
708 natively, the case "[$wd, "."]" as $srcpath is specialcased - 646 natively, the case "[$wd, "."]" as $srcpath is specialcased -
709 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.
710 648
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
711 aio_mkdir $pathname, $mode, $callback->($status) 664 aio_mkdir $pathname, $mode, $callback->($status)
712 Asynchronously mkdir (create) a directory and call the callback with 665 Asynchronously mkdir (create) a directory and call the callback with
713 the result code. $mode will be modified by the umask at the time the 666 the result code. $mode will be modified by the umask at the time the
714 request is executed, so do not change your umask. 667 request is executed, so do not change your umask.
715 668
… …
737 The flags are a combination of the following constants, ORed 690 The flags are a combination of the following constants, ORed
738 together (the flags will also be passed to the callback, possibly 691 together (the flags will also be passed to the callback, possibly
739 modified): 692 modified):
740 693
741 IO::AIO::READDIR_DENTS 694 IO::AIO::READDIR_DENTS
742 When this flag is off, then the callback gets an arrayref 695 Normally the callback gets an arrayref consisting of names only
743 consisting of names only (as with "aio_readdir"), otherwise it 696 (as with "aio_readdir"). If this flag is set, then the callback
744 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 697 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
745 describing a single directory entry in more detail. 698 describing a single directory entry in more detail:
746 699
747 $name is the name of the entry. 700 $name is the name of the entry.
748 701
749 $type is one of the "IO::AIO::DT_xxx" constants: 702 $type is one of the "IO::AIO::DT_xxx" constants:
750 703
751 "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",
752 "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",
753 "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".
754 707
755 "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
756 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
757 reasons, the $type scalars are read-only: you can not modify 710 speed/memory reasons, the $type scalars are read-only: you must
758 them. 711 not modify them.
759 712
760 $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
761 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
762 unspecified content on systems that do not deliver the inode 715 unspecified content on systems that do not deliver the inode
763 information. 716 information.
… …
775 of which names with short names are tried first. 728 of which names with short names are tried first.
776 729
777 IO::AIO::READDIR_STAT_ORDER 730 IO::AIO::READDIR_STAT_ORDER
778 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
779 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
780 to stat() all files in the given directory, then the returned 733 to stat() most or all files in the given directory, then the
781 order will likely be fastest. 734 returned order will likely be faster.
782 735
783 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 736 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
784 specified, then the likely dirs come first, resulting in a less 737 specified, then the likely dirs come first, resulting in a less
785 optimal stat order. 738 optimal stat order for stat'ing all entries, but likely a more
739 optimal order for finding subdirectories.
786 740
787 IO::AIO::READDIR_FOUND_UNKNOWN 741 IO::AIO::READDIR_FOUND_UNKNOWN
788 This flag should not be set when calling "aio_readdirx". 742 This flag should not be set when calling "aio_readdirx".
789 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
790 $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
791 flag therefore indicates that all $type's are known, which can 745 flag therefore indicates that all $type's are known, which can
792 be used to speed up some algorithms. 746 be used to speed up some algorithms.
793 747
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
794 aio_load $pathname, $data, $callback->($status) 775 aio_load $pathname, $data, $callback->($status)
795 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
796 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.
797 781
798 aio_copy $srcpath, $dstpath, $callback->($status) 782 aio_copy $srcpath, $dstpath, $callback->($status)
799 Try to copy the *file* (directories not supported as either source 783 Try to copy the *file* (directories not supported as either source
800 or destination) from $srcpath to $dstpath and call the callback with 784 or destination) from $srcpath to $dstpath and call the callback with
801 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.
802 788
803 This is a composite request that creates the destination file with 789 This is a composite request that creates the destination file with
804 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
805 "aio_sendfile", followed by restoring atime, mtime, access mode and 791 "aio_sendfile", followed by restoring atime, mtime, access mode and
806 uid/gid, in that order. 792 uid/gid, in that order.
… …
823 to efficiently separate the entries of directory $path into two sets 809 to efficiently separate the entries of directory $path into two sets
824 of names, directories you can recurse into (directories), and ones 810 of names, directories you can recurse into (directories), and ones
825 you cannot recurse into (everything else, including symlinks to 811 you cannot recurse into (everything else, including symlinks to
826 directories). 812 directories).
827 813
828 "aio_scandir" is a composite request that creates of many sub 814 "aio_scandir" is a composite request that generates many sub
829 requests_ $maxreq specifies the maximum number of outstanding aio 815 requests. $maxreq specifies the maximum number of outstanding aio
830 requests that this function generates. If it is "<= 0", then a 816 requests that this function generates. If it is "<= 0", then a
831 suitable default will be chosen (currently 4). 817 suitable default will be chosen (currently 4).
832 818
833 On error, the callback is called without arguments, otherwise it 819 On error, the callback is called without arguments, otherwise it
834 receives two array-refs with path-relative entry names. 820 receives two array-refs with path-relative entry names.
… …
881 Delete a directory tree starting (and including) $path, return the 867 Delete a directory tree starting (and including) $path, return the
882 status of the final "rmdir" only. This is a composite request that 868 status of the final "rmdir" only. This is a composite request that
883 uses "aio_scandir" to recurse into and rmdir directories, and unlink 869 uses "aio_scandir" to recurse into and rmdir directories, and unlink
884 everything else. 870 everything else.
885 871
872 aio_fcntl $fh, $cmd, $arg, $callback->($status)
873 aio_ioctl $fh, $request, $buf, $callback->($status)
874 These work just like the "fcntl" and "ioctl" built-in functions,
875 except they execute asynchronously and pass the return value to the
876 callback.
877
878 Both calls can be used for a lot of things, some of which make more
879 sense to run asynchronously in their own thread, while some others
880 make less sense. For example, calls that block waiting for external
881 events, such as locking, will also lock down an I/O thread while it
882 is waiting, which can deadlock the whole I/O system. At the same
883 time, there might be no alternative to using a thread to wait.
884
885 So in general, you should only use these calls for things that do
886 (filesystem) I/O, not for things that wait for other events
887 (network, other processes), although if you are careful and know
888 what you are doing, you still can.
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
886 aio_sync $callback->($status) 920 aio_sync $callback->($status)
887 Asynchronously call sync and call the callback when finished. 921 Asynchronously call sync and call the callback when finished.
888 922
889 aio_fsync $fh, $callback->($status) 923 aio_fsync $fh, $callback->($status)
890 Asynchronously call fsync on the given filehandle and call the 924 Asynchronously call fsync on the given filehandle and call the
… …
926 Future versions of this function might fall back to other methods 960 Future versions of this function might fall back to other methods
927 when "fsync" on the directory fails (such as calling "sync"). 961 when "fsync" on the directory fails (such as calling "sync").
928 962
929 Passes 0 when everything went ok, and -1 on error. 963 Passes 0 when everything went ok, and -1 on error.
930 964
931 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 965 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
932 $callback->($status) 966 $callback->($status)
933 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
934 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
935 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,
936 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
… …
938 972
939 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
940 memory area starting at $offset in the string and ending $length 974 memory area starting at $offset in the string and ending $length
941 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
942 $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
943 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
944 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 978 an optional "IO::AIO::MS_INVALIDATE".
945 979
946 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 980 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
947 $callback->($status) 981 $callback->($status)
948 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
949 mmap(2)ed scalars. 983 mmap(2)ed scalars.
… …
1035 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1069 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1036 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1070 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1037 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1071 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1038 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1072 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1039 1073
1040 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
1041 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
1042 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
1043 number of extents. The code works around all these issues if $count 1077 large number of extents. The code (only) works around all these
1044 is undef. 1078 issues if $count is "undef".
1045 1079
1046 aio_group $callback->(...) 1080 aio_group $callback->(...)
1047 This is a very special aio request: Instead of doing something, it 1081 This is a very special aio request: Instead of doing something, it
1048 is a container for other aio requests, which is useful if you want 1082 is a container for other aio requests, which is useful if you want
1049 to bundle many requests into a single, composite, request with a 1083 to bundle many requests into a single, composite, request with a
… …
1129 aio_stat [$etcdir, "passwd"], sub { 1163 aio_stat [$etcdir, "passwd"], sub {
1130 # yay 1164 # yay
1131 }; 1165 };
1132 }; 1166 };
1133 1167
1134 That "aio_wd" is a request and not a normal function shows that creating 1168 The fact that "aio_wd" is a request and not a normal function shows that
1135 an IO::AIO::WD object is itself a potentially blocking operation, which 1169 creating an IO::AIO::WD object is itself a potentially blocking
1136 is why it is done asynchronously. 1170 operation, which is why it is done asynchronously.
1137 1171
1138 To stat the directory obtained with "aio_wd" above, one could write 1172 To stat the directory obtained with "aio_wd" above, one could write
1139 either of the following three request calls: 1173 either of the following three request calls:
1140 1174
1141 aio_lstat "/etc" , sub { ... # pathname as normal string 1175 aio_lstat "/etc" , sub { ... # pathname as normal string
… …
1158 There are some caveats: when directories get renamed (or deleted), the 1192 There are some caveats: when directories get renamed (or deleted), the
1159 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
1160 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,
1161 will still point to the original directory. Most functions accepting a 1195 will still point to the original directory. Most functions accepting a
1162 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
1163 older systems. Some functions (such as realpath) will always rely on the 1197 older systems. Some functions (such as "aio_realpath") will always rely
1164 string form of the pathname. 1198 on the string form of the pathname.
1165 1199
1166 So this functionality is mainly useful to get some protection against 1200 So this functionality is mainly useful to get some protection against
1167 "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
1168 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
1169 directory (e.g. when stat'ing all files in a directory). 1203 directory (e.g. when stat'ing all files in a directory).
… …
1180 instead of a working directory object and $! is set appropriately. 1214 instead of a working directory object and $! is set appropriately.
1181 Since passing "undef" as working directory component of a pathname 1215 Since passing "undef" as working directory component of a pathname
1182 fails the request with "ENOENT", there is often no need for error 1216 fails the request with "ENOENT", there is often no need for error
1183 checking in the "aio_wd" callback, as future requests using the 1217 checking in the "aio_wd" callback, as future requests using the
1184 value will fail in the expected way. 1218 value will fail in the expected way.
1185
1186 If this call isn't available because your OS lacks it or it couldn't
1187 be detected, it will be emulated by calling "fsync" instead.
1188 1219
1189 IO::AIO::CWD 1220 IO::AIO::CWD
1190 This is a compiletime constant (object) that represents the process 1221 This is a compiletime constant (object) that represents the process
1191 current working directory. 1222 current working directory.
1192 1223
… …
1522 1553
1523 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
1524 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
1525 inexact: Better use an "aio_group" together with a feed callback. 1556 inexact: Better use an "aio_group" together with a feed callback.
1526 1557
1527 It's 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
1528 stat a lot of files, you can write somehting like this: 1559 stat a lot of files, you can write something like this:
1529 1560
1530 IO::AIO::max_outstanding 32; 1561 IO::AIO::max_outstanding 32;
1531 1562
1532 for my $path (...) { 1563 for my $path (...) {
1533 aio_stat $path , ...; 1564 aio_stat $path , ...;
… …
1562 1593
1563 IO::AIO::npending 1594 IO::AIO::npending
1564 Returns the number of requests currently in the pending state 1595 Returns the number of requests currently in the pending state
1565 (executed, but not yet processed by poll_cb). 1596 (executed, but not yet processed by poll_cb).
1566 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
1567 MISCELLANEOUS FUNCTIONS 1660 MISCELLANEOUS FUNCTIONS
1568 IO::AIO implements some functions that might be useful, but are not 1661 IO::AIO implements some functions that are useful when you want to use
1569 asynchronous. 1662 some "Advanced I/O" function not available to in Perl, without going the
1663 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
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.
1570 1689
1571 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1690 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1572 Calls the "eio_sendfile_sync" function, which is like 1691 Calls the "eio_sendfile_sync" function, which is like
1573 "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
1574 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
… …
1591 details). The following advice constants are available: 1710 details). The following advice constants are available:
1592 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1711 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1593 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1712 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1594 "IO::AIO::MADV_DONTNEED". 1713 "IO::AIO::MADV_DONTNEED".
1595 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
1596 On systems that do not implement "posix_madvise", this function 1719 On systems that do not implement "posix_madvise", this function
1597 returns ENOSYS, otherwise the return value of "posix_madvise". 1720 returns ENOSYS, otherwise the return value of "posix_madvise".
1598 1721
1599 IO::AIO::mprotect $scalar, $offset, $len, $protect 1722 IO::AIO::mprotect $scalar, $offset, $len, $protect
1600 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1723 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1601 $scalar (see its manpage for details). The following protect 1724 $scalar (see its manpage for details). The following protect
1602 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1725 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1603 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1726 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1604 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
1605 On systems that do not implement "mprotect", this function returns 1732 On systems that do not implement "mprotect", this function returns
1606 ENOSYS, otherwise the return value of "mprotect". 1733 ENOSYS, otherwise the return value of "mprotect".
1607 1734
1608 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1735 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1609 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
1610 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
1611 on success, and false otherwise. 1738 on success, and false otherwise.
1612 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
1613 The only operations allowed on the scalar are "substr"/"vec" that 1744 The only operations allowed on the mmapped scalar are
1614 don't change the string length, and most read-only operations such 1745 "substr"/"vec", which don't change the string length, and most
1615 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.
1616 1748
1617 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.
1618 1750
1619 The memory map associated with the $scalar is automatically removed 1751 The memory map associated with the $scalar is automatically removed
1620 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1752 when the $scalar is undef'd or destroyed, or when the
1621 "IO::AIO::munmap" functions are called. 1753 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1622 1754
1623 This calls the "mmap"(2) function internally. See your system's 1755 This calls the "mmap"(2) function internally. See your system's
1624 manual page for details on the $length, $prot and $flags parameters. 1756 manual page for details on the $length, $prot and $flags parameters.
1625 1757
1626 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
… …
1630 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1762 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1631 "IO::AIO::PROT_WRITE", 1763 "IO::AIO::PROT_WRITE",
1632 1764
1633 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1765 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1634 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1766 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1635 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1767 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1636 (which is set to "MAP_ANON" if your system only provides this 1768 "MAP_ANON" if your system only provides this constant),
1769 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1637 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1770 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1771 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1638 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1772 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1639 "IO::AIO::MAP_NONBLOCK" 1773 "IO::AIO::MAP_STACK".
1640 1774
1641 If $fh is "undef", then a file descriptor of -1 is passed. 1775 If $fh is "undef", then a file descriptor of -1 is passed.
1642 1776
1643 $offset is the offset from the start of the file - it generally must 1777 $offset is the offset from the start of the file - it generally must
1644 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1778 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1656 1790
1657 my $fast_md5 = md5 $data; 1791 my $fast_md5 = md5 $data;
1658 1792
1659 IO::AIO::munmap $scalar 1793 IO::AIO::munmap $scalar
1660 Removes a previous mmap and undefines the $scalar. 1794 Removes a previous mmap and undefines the $scalar.
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".
1661 1819
1662 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1820 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1663 Calls the "munlock" function, undoing the effects of a previous 1821 Calls the "munlock" function, undoing the effects of a previous
1664 "aio_mlock" call (see its description for details). 1822 "aio_mlock" call (see its description for details).
1665 1823
… …
1682 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT". 1840 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1683 1841
1684 See the splice(2) manpage for details. 1842 See the splice(2) manpage for details.
1685 1843
1686 IO::AIO::tee $r_fh, $w_fh, $length, $flags 1844 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1687 Calls the GNU/Linux tee(2) syscall, see it's manpage and the 1845 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1688 description for "IO::AIO::splice" above for details. 1846 description for "IO::AIO::splice" above for details.
1847
1848 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1849 Attempts to query or change the pipe buffer size. Obviously works
1850 only on pipes, and currently works only on GNU/Linux systems, and
1851 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1852 influence pipe buffer size on other systems, drop me a note.
1853
1854 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1855 This is a direct interface to the Linux pipe2(2) system call. If
1856 $flags is missing or 0, then this should be the same as a call to
1857 perl's built-in "pipe" function and create a new pipe, and works on
1858 systems that lack the pipe2 syscall. On win32, this case invokes
1859 "_pipe (..., 4096, O_BINARY)".
1860
1861 If $flags is non-zero, it tries to invoke the pipe2 system call with
1862 the given flags (Linux 2.6.27, glibc 2.9).
1863
1864 On success, the read and write file handles are returned.
1865
1866 On error, nothing will be returned. If the pipe2 syscall is missing
1867 and $flags is non-zero, fails with "ENOSYS".
1868
1869 Please refer to pipe2(2) for more info on the $flags, but at the
1870 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1871 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1872 supported.
1873
1874 Example: create a pipe race-free w.r.t. threads and fork:
1875
1876 my ($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.
1689 1957
1690EVENT LOOP INTEGRATION 1958EVENT LOOP INTEGRATION
1691 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1959 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1692 automatically into many event loops: 1960 automatically into many event loops:
1693 1961
… …
1743 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
1744 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.
1745 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)
1746 behaviour. 2014 behaviour.
1747 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
1748 MEMORY USAGE 2024 MEMORY USAGE
1749 Per-request usage: 2025 Per-request usage:
1750 2026
1751 Each aio request uses - depending on your architecture - around 100-200 2027 Each aio request uses - depending on your architecture - around 100-200
1752 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
… …
1762 In the execution phase, some aio requests require more memory for 2038 In the execution phase, some aio requests require more memory for
1763 temporary buffers, and each thread requires a stack and other data 2039 temporary buffers, and each thread requires a stack and other data
1764 structures (usually around 16k-128k, depending on the OS). 2040 structures (usually around 16k-128k, depending on the OS).
1765 2041
1766KNOWN BUGS 2042KNOWN BUGS
1767 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.
1768 2054
1769SEE ALSO 2055SEE ALSO
1770 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
1771 more natural syntax. 2057 more natural syntax.
1772 2058

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