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Revision 1.55 by root, Sat Jan 25 00:15:52 2014 UTC vs.
Revision 1.63 by root, Mon Mar 4 10:28:38 2019 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
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90 94
91 # file contents now in $contents 95 # file contents now in $contents
92 print $contents; 96 print $contents;
93 97
94 # exit event loop and program 98 # exit event loop and program
95 EV::unloop; 99 EV::break;
96 }; 100 };
97 }; 101 };
98 102
99 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
100 # check for sockets etc. etc. 104 # check for sockets etc. etc.
101 105
102 # process events as long as there are some: 106 # process events as long as there are some:
103 EV::loop; 107 EV::run;
104 108
105REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
106 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
107 not directly visible to Perl. 111 not directly visible to Perl.
108 112
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171 aio_unlink $pathname, $callback->($status) 175 aio_unlink $pathname, $callback->($status)
172 aio_mknod $pathname, $mode, $dev, $callback->($status) 176 aio_mknod $pathname, $mode, $dev, $callback->($status)
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, $callback->($link) 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
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184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
185 aio_load $pathname, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
186 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
187 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
188 aio_rmtree $pathname, $callback->($status) 193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
189 aio_sync $callback->($status) 196 aio_sync $callback->($status)
190 aio_syncfs $fh, $callback->($status) 197 aio_syncfs $fh, $callback->($status)
191 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
192 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
193 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
194 aio_pathsync $pathname, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
195 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
196 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
197 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
198 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
199 aio_group $callback->(...) 206 aio_group $callback->(...)
200 aio_nop $callback->() 207 aio_nop $callback->()
… …
214 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
215 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
216 IO::AIO::nreqs 223 IO::AIO::nreqs
217 IO::AIO::nready 224 IO::AIO::nready
218 IO::AIO::npending 225 IO::AIO::npending
226 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
227 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
219 228
220 IO::AIO::sendfile $ofh, $ifh, $offset, $count 229 IO::AIO::sendfile $ofh, $ifh, $offset, $count
221 IO::AIO::fadvise $fh, $offset, $len, $advice 230 IO::AIO::fadvise $fh, $offset, $len, $advice
222 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] 231 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
223 IO::AIO::munmap $scalar 232 IO::AIO::munmap $scalar
233 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
224 IO::AIO::madvise $scalar, $offset, $length, $advice 234 IO::AIO::madvise $scalar, $offset, $length, $advice
225 IO::AIO::mprotect $scalar, $offset, $length, $protect 235 IO::AIO::mprotect $scalar, $offset, $length, $protect
226 IO::AIO::munlock $scalar, $offset = 0, $length = undef 236 IO::AIO::munlock $scalar, $offset = 0, $length = undef
227 IO::AIO::munlockall 237 IO::AIO::munlockall
228 238
… …
330 "O_APPEND"), the following POSIX and non-POSIX constants are 340 "O_APPEND"), the following POSIX and non-POSIX constants are
331 available (missing ones on your system are, as usual, 0): 341 available (missing ones on your system are, as usual, 0):
332 342
333 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 343 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
334 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 344 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
335 "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".
336 347
337 aio_close $fh, $callback->($status) 348 aio_close $fh, $callback->($status)
338 Asynchronously close a file and call the callback with the result 349 Asynchronously close a file and call the callback with the result
339 code. 350 code.
340 351
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370 381
371 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
372 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373 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
374 $offset into the scalar given by $data and offset $dataoffset and 385 $offset into the scalar given by $data and offset $dataoffset and
375 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
376 error, just like the syscall). 387 -1 on error, just like the syscall).
377 388
378 "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
379 offset plus the actual number of bytes read. 390 offset plus the actual number of bytes read.
380 391
381 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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438 As native sendfile syscalls (as practically any non-POSIX interface 449 As native sendfile syscalls (as practically any non-POSIX interface
439 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
440 rather buggy on many systems, this implementation tries to work 451 rather buggy on many systems, this implementation tries to work
441 around some known bugs in Linux and FreeBSD kernels (probably 452 around some known bugs in Linux and FreeBSD kernels (probably
442 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
443 the return value of "aio_sendfile" - fewre bytes than expected might 454 the return value of "aio_sendfile" - fewer bytes than expected might
444 have been transferred. 455 have been transferred.
445 456
446 aio_readahead $fh,$offset,$length, $callback->($retval) 457 aio_readahead $fh,$offset,$length, $callback->($retval)
447 "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
448 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
… …
452 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
453 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
454 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
455 is left unchanged. 466 is left unchanged.
456 467
457 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
458 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
459 similar effect. 470 similar effect.
460 471
461 aio_stat $fh_or_path, $callback->($status) 472 aio_stat $fh_or_path, $callback->($status)
462 aio_lstat $fh, $callback->($status) 473 aio_lstat $fh, $callback->($status)
463 Works like perl's "stat" or "lstat" in void context. The callback 474 Works almost exactly like perl's "stat" or "lstat" in void context.
464 will be called after the stat and the results will be available 475 The callback will be called after the stat and the results will be
465 using "stat _" or "-s _" etc... 476 available using "stat _" or "-s _" and other tests (with the
477 exception of "-B" and "-T").
466 478
467 The pathname passed to "aio_stat" must be absolute. See API NOTES, 479 The pathname passed to "aio_stat" must be absolute. See API NOTES,
468 above, for an explanation. 480 above, for an explanation.
469 481
470 Currently, the stats are always 64-bit-stats, i.e. instead of 482 Currently, the stats are always 64-bit-stats, i.e. instead of
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478 back on traditional behaviour). 490 back on traditional behaviour).
479 491
480 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 492 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
481 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 493 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
482 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 494 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
495
496 To access higher resolution stat timestamps, see "SUBSECOND STAT
497 TIME ACCESS".
483 498
484 Example: Print the length of /etc/passwd: 499 Example: Print the length of /etc/passwd:
485 500
486 aio_stat "/etc/passwd", sub { 501 aio_stat "/etc/passwd", sub {
487 $_[0] and die "stat failed: $!"; 502 $_[0] and die "stat failed: $!";
… …
529 namemax => 255, 544 namemax => 255,
530 frsize => 1024, 545 frsize => 1024,
531 fsid => 1810 546 fsid => 1810
532 } 547 }
533 548
534 Here is a (likely partial - send me updates!) list of fsid values
535 used by Linux - it is safe to hardcode these when $^O is "linux":
536
537 0x0000adf5 adfs
538 0x0000adff affs
539 0x5346414f afs
540 0x09041934 anon-inode filesystem
541 0x00000187 autofs
542 0x42465331 befs
543 0x1badface bfs
544 0x42494e4d binfmt_misc
545 0x9123683e btrfs
546 0x0027e0eb cgroupfs
547 0xff534d42 cifs
548 0x73757245 coda
549 0x012ff7b7 coh
550 0x28cd3d45 cramfs
551 0x453dcd28 cramfs-wend (wrong endianness)
552 0x64626720 debugfs
553 0x00001373 devfs
554 0x00001cd1 devpts
555 0x0000f15f ecryptfs
556 0x00414a53 efs
557 0x0000137d ext
558 0x0000ef53 ext2/ext3
559 0x0000ef51 ext2
560 0x00004006 fat
561 0x65735546 fuseblk
562 0x65735543 fusectl
563 0x0bad1dea futexfs
564 0x01161970 gfs2
565 0x47504653 gpfs
566 0x00004244 hfs
567 0xf995e849 hpfs
568 0x958458f6 hugetlbfs
569 0x2bad1dea inotifyfs
570 0x00009660 isofs
571 0x000072b6 jffs2
572 0x3153464a jfs
573 0x6b414653 k-afs
574 0x0bd00bd0 lustre
575 0x0000137f minix
576 0x0000138f minix 30 char names
577 0x00002468 minix v2
578 0x00002478 minix v2 30 char names
579 0x00004d5a minix v3
580 0x19800202 mqueue
581 0x00004d44 msdos
582 0x0000564c novell
583 0x00006969 nfs
584 0x6e667364 nfsd
585 0x00003434 nilfs
586 0x5346544e ntfs
587 0x00009fa1 openprom
588 0x7461636F ocfs2
589 0x00009fa0 proc
590 0x6165676c pstorefs
591 0x0000002f qnx4
592 0x858458f6 ramfs
593 0x52654973 reiserfs
594 0x00007275 romfs
595 0x67596969 rpc_pipefs
596 0x73636673 securityfs
597 0xf97cff8c selinux
598 0x0000517b smb
599 0x534f434b sockfs
600 0x73717368 squashfs
601 0x62656572 sysfs
602 0x012ff7b6 sysv2
603 0x012ff7b5 sysv4
604 0x01021994 tmpfs
605 0x15013346 udf
606 0x00011954 ufs
607 0x54190100 ufs byteswapped
608 0x00009fa2 usbdevfs
609 0x01021997 v9fs
610 0xa501fcf5 vxfs
611 0xabba1974 xenfs
612 0x012ff7b4 xenix
613 0x58465342 xfs
614 0x012fd16d xia
615
616 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 549 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
617 Works like perl's "utime" function (including the special case of 550 Works like perl's "utime" function (including the special case of
618 $atime and $mtime being undef). Fractional times are supported if 551 $atime and $mtime being undef). Fractional times are supported if
619 the underlying syscalls support them. 552 the underlying syscalls support them.
620 553
621 When called with a pathname, uses utimes(2) if available, otherwise 554 When called with a pathname, uses utimensat(2) or utimes(2) if
622 utime(2). If called on a file descriptor, uses futimes(2) if 555 available, otherwise utime(2). If called on a file descriptor, uses
623 available, otherwise returns ENOSYS, so this is not portable. 556 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
557 this is not portable.
624 558
625 Examples: 559 Examples:
626 560
627 # set atime and mtime to current time (basically touch(1)): 561 # set atime and mtime to current time (basically touch(1)):
628 aio_utime "path", undef, undef; 562 aio_utime "path", undef, undef;
… …
643 577
644 aio_truncate $fh_or_path, $offset, $callback->($status) 578 aio_truncate $fh_or_path, $offset, $callback->($status)
645 Works like truncate(2) or ftruncate(2). 579 Works like truncate(2) or ftruncate(2).
646 580
647 aio_allocate $fh, $mode, $offset, $len, $callback->($status) 581 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
648 Allocates or freed disk space according to the $mode argument. See 582 Allocates or frees disk space according to the $mode argument. See
649 the linux "fallocate" docuemntation for details. 583 the linux "fallocate" documentation for details.
650 584
651 $mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to 585 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
652 allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | 586 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
653 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. 587 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
654 588
589 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
590 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
591 "FALLOC_FL_INSERT_RANGE" to insert a range and
592 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
593 fallocate(2) manpage).
594
655 The file system block size used by "fallocate" is presumably the 595 The file system block size used by "fallocate" is presumably the
656 "f_bsize" returned by "statvfs". 596 "f_bsize" returned by "statvfs", but different filesystems and
597 filetypes can dictate other limitations.
657 598
658 If "fallocate" isn't available or cannot be emulated (currently no 599 If "fallocate" isn't available or cannot be emulated (currently no
659 emulation will be attempted), passes -1 and sets $! to "ENOSYS". 600 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
660 601
661 aio_chmod $fh_or_path, $mode, $callback->($status) 602 aio_chmod $fh_or_path, $mode, $callback->($status)
… …
705 646
706 On systems that support the AIO::WD working directory abstraction 647 On systems that support the AIO::WD working directory abstraction
707 natively, the case "[$wd, "."]" as $srcpath is specialcased - 648 natively, the case "[$wd, "."]" as $srcpath is specialcased -
708 instead of failing, "rename" is called on the absolute path of $wd. 649 instead of failing, "rename" is called on the absolute path of $wd.
709 650
651 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
652 Basically a version of "aio_rename" with an additional $flags
653 argument. Calling this with "$flags=0" is the same as calling
654 "aio_rename".
655
656 Non-zero flags are currently only supported on GNU/Linux systems
657 that support renameat2. Other systems fail with "ENOSYS" in this
658 case.
659
660 The following constants are available (missing ones are, as usual
661 0), see renameat2(2) for details:
662
663 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
664 "IO::AIO::RENAME_WHITEOUT".
665
710 aio_mkdir $pathname, $mode, $callback->($status) 666 aio_mkdir $pathname, $mode, $callback->($status)
711 Asynchronously mkdir (create) a directory and call the callback with 667 Asynchronously mkdir (create) a directory and call the callback with
712 the result code. $mode will be modified by the umask at the time the 668 the result code. $mode will be modified by the umask at the time the
713 request is executed, so do not change your umask. 669 request is executed, so do not change your umask.
714 670
… …
736 The flags are a combination of the following constants, ORed 692 The flags are a combination of the following constants, ORed
737 together (the flags will also be passed to the callback, possibly 693 together (the flags will also be passed to the callback, possibly
738 modified): 694 modified):
739 695
740 IO::AIO::READDIR_DENTS 696 IO::AIO::READDIR_DENTS
741 When this flag is off, then the callback gets an arrayref 697 Normally the callback gets an arrayref consisting of names only
742 consisting of names only (as with "aio_readdir"), otherwise it 698 (as with "aio_readdir"). If this flag is set, then the callback
743 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 699 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
744 describing a single directory entry in more detail. 700 describing a single directory entry in more detail:
745 701
746 $name is the name of the entry. 702 $name is the name of the entry.
747 703
748 $type is one of the "IO::AIO::DT_xxx" constants: 704 $type is one of the "IO::AIO::DT_xxx" constants:
749 705
750 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 706 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
751 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 707 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
752 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 708 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
753 709
754 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 710 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
755 you need to know, you have to run stat yourself. Also, for speed 711 you need to know, you have to run stat yourself. Also, for
756 reasons, the $type scalars are read-only: you can not modify 712 speed/memory reasons, the $type scalars are read-only: you must
757 them. 713 not modify them.
758 714
759 $inode is the inode number (which might not be exact on systems 715 $inode is the inode number (which might not be exact on systems
760 with 64 bit inode numbers and 32 bit perls). This field has 716 with 64 bit inode numbers and 32 bit perls). This field has
761 unspecified content on systems that do not deliver the inode 717 unspecified content on systems that do not deliver the inode
762 information. 718 information.
… …
774 of which names with short names are tried first. 730 of which names with short names are tried first.
775 731
776 IO::AIO::READDIR_STAT_ORDER 732 IO::AIO::READDIR_STAT_ORDER
777 When this flag is set, then the names will be returned in an 733 When this flag is set, then the names will be returned in an
778 order suitable for stat()'ing each one. That is, when you plan 734 order suitable for stat()'ing each one. That is, when you plan
779 to stat() all files in the given directory, then the returned 735 to stat() most or all files in the given directory, then the
780 order will likely be fastest. 736 returned order will likely be faster.
781 737
782 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 738 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
783 specified, then the likely dirs come first, resulting in a less 739 specified, then the likely dirs come first, resulting in a less
784 optimal stat order. 740 optimal stat order for stat'ing all entries, but likely a more
741 optimal order for finding subdirectories.
785 742
786 IO::AIO::READDIR_FOUND_UNKNOWN 743 IO::AIO::READDIR_FOUND_UNKNOWN
787 This flag should not be set when calling "aio_readdirx". 744 This flag should not be set when calling "aio_readdirx".
788 Instead, it is being set by "aio_readdirx", when any of the 745 Instead, it is being set by "aio_readdirx", when any of the
789 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this 746 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
790 flag therefore indicates that all $type's are known, which can 747 flag therefore indicates that all $type's are known, which can
791 be used to speed up some algorithms. 748 be used to speed up some algorithms.
792 749
750 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
751 Opens, reads and closes the given file. The data is put into $data,
752 which is resized as required.
753
754 If $offset is negative, then it is counted from the end of the file.
755
756 If $length is zero, then the remaining length of the file is used.
757 Also, in this case, the same limitations to modifying $data apply as
758 when IO::AIO::mmap is used, i.e. it must only be modified in-place
759 with "substr". If the size of the file is known, specifying a
760 non-zero $length results in a performance advantage.
761
762 This request is similar to the older "aio_load" request, but since
763 it is a single request, it might be more efficient to use.
764
765 Example: load /etc/passwd into $passwd.
766
767 my $passwd;
768 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
769 $_[0] >= 0
770 or die "/etc/passwd: $!\n";
771
772 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
773 print $passwd;
774 };
775 IO::AIO::flush;
776
793 aio_load $pathname, $data, $callback->($status) 777 aio_load $pathname, $data, $callback->($status)
794 This is a composite request that tries to fully load the given file 778 This is a composite request that tries to fully load the given file
795 into memory. Status is the same as with aio_read. 779 into memory. Status is the same as with aio_read.
780
781 Using "aio_slurp" might be more efficient, as it is a single
782 request.
796 783
797 aio_copy $srcpath, $dstpath, $callback->($status) 784 aio_copy $srcpath, $dstpath, $callback->($status)
798 Try to copy the *file* (directories not supported as either source 785 Try to copy the *file* (directories not supported as either source
799 or destination) from $srcpath to $dstpath and call the callback with 786 or destination) from $srcpath to $dstpath and call the callback with
800 a status of 0 (ok) or -1 (error, see $!). 787 a status of 0 (ok) or -1 (error, see $!).
788
789 Existing destination files will be truncated.
801 790
802 This is a composite request that creates the destination file with 791 This is a composite request that creates the destination file with
803 mode 0200 and copies the contents of the source file into it using 792 mode 0200 and copies the contents of the source file into it using
804 "aio_sendfile", followed by restoring atime, mtime, access mode and 793 "aio_sendfile", followed by restoring atime, mtime, access mode and
805 uid/gid, in that order. 794 uid/gid, in that order.
… …
822 to efficiently separate the entries of directory $path into two sets 811 to efficiently separate the entries of directory $path into two sets
823 of names, directories you can recurse into (directories), and ones 812 of names, directories you can recurse into (directories), and ones
824 you cannot recurse into (everything else, including symlinks to 813 you cannot recurse into (everything else, including symlinks to
825 directories). 814 directories).
826 815
827 "aio_scandir" is a composite request that creates of many sub 816 "aio_scandir" is a composite request that generates many sub
828 requests_ $maxreq specifies the maximum number of outstanding aio 817 requests. $maxreq specifies the maximum number of outstanding aio
829 requests that this function generates. If it is "<= 0", then a 818 requests that this function generates. If it is "<= 0", then a
830 suitable default will be chosen (currently 4). 819 suitable default will be chosen (currently 4).
831 820
832 On error, the callback is called without arguments, otherwise it 821 On error, the callback is called without arguments, otherwise it
833 receives two array-refs with path-relative entry names. 822 receives two array-refs with path-relative entry names.
… …
880 Delete a directory tree starting (and including) $path, return the 869 Delete a directory tree starting (and including) $path, return the
881 status of the final "rmdir" only. This is a composite request that 870 status of the final "rmdir" only. This is a composite request that
882 uses "aio_scandir" to recurse into and rmdir directories, and unlink 871 uses "aio_scandir" to recurse into and rmdir directories, and unlink
883 everything else. 872 everything else.
884 873
874 aio_fcntl $fh, $cmd, $arg, $callback->($status)
875 aio_ioctl $fh, $request, $buf, $callback->($status)
876 These work just like the "fcntl" and "ioctl" built-in functions,
877 except they execute asynchronously and pass the return value to the
878 callback.
879
880 Both calls can be used for a lot of things, some of which make more
881 sense to run asynchronously in their own thread, while some others
882 make less sense. For example, calls that block waiting for external
883 events, such as locking, will also lock down an I/O thread while it
884 is waiting, which can deadlock the whole I/O system. At the same
885 time, there might be no alternative to using a thread to wait.
886
887 So in general, you should only use these calls for things that do
888 (filesystem) I/O, not for things that wait for other events
889 (network, other processes), although if you are careful and know
890 what you are doing, you still can.
891
892 The following constants are available (missing ones are, as usual
893 0):
894
895 "F_DUPFD_CLOEXEC",
896
897 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
898
899 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
900 "FIDEDUPERANGE".
901
902 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
903 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
904
905 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
906 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
907 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
908
909 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
910 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
911 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
912 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
913 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
914
915 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
916 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
917 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
918 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
919 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
920 "FS_XFLAG_HASATTR",
921
885 aio_sync $callback->($status) 922 aio_sync $callback->($status)
886 Asynchronously call sync and call the callback when finished. 923 Asynchronously call sync and call the callback when finished.
887 924
888 aio_fsync $fh, $callback->($status) 925 aio_fsync $fh, $callback->($status)
889 Asynchronously call fsync on the given filehandle and call the 926 Asynchronously call fsync on the given filehandle and call the
… …
925 Future versions of this function might fall back to other methods 962 Future versions of this function might fall back to other methods
926 when "fsync" on the directory fails (such as calling "sync"). 963 when "fsync" on the directory fails (such as calling "sync").
927 964
928 Passes 0 when everything went ok, and -1 on error. 965 Passes 0 when everything went ok, and -1 on error.
929 966
930 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 967 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
931 $callback->($status) 968 $callback->($status)
932 This is a rather advanced IO::AIO call, which only works on 969 This is a rather advanced IO::AIO call, which only works on
933 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 970 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
934 also works on data scalars managed by the Sys::Mmap or Mmap modules, 971 also works on data scalars managed by the Sys::Mmap or Mmap modules,
935 note that the scalar must only be modified in-place while an aio 972 note that the scalar must only be modified in-place while an aio
… …
937 974
938 It calls the "msync" function of your OS, if available, with the 975 It calls the "msync" function of your OS, if available, with the
939 memory area starting at $offset in the string and ending $length 976 memory area starting at $offset in the string and ending $length
940 bytes later. If $length is negative, counts from the end, and if 977 bytes later. If $length is negative, counts from the end, and if
941 $length is "undef", then it goes till the end of the string. The 978 $length is "undef", then it goes till the end of the string. The
942 flags can be a combination of "IO::AIO::MS_ASYNC", 979 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
943 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 980 an optional "IO::AIO::MS_INVALIDATE".
944 981
945 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 982 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
946 $callback->($status) 983 $callback->($status)
947 This is a rather advanced IO::AIO call, which works best on 984 This is a rather advanced IO::AIO call, which works best on
948 mmap(2)ed scalars. 985 mmap(2)ed scalars.
… …
979 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1016 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
980 aio_mlock $data; # mlock in background 1017 aio_mlock $data; # mlock in background
981 1018
982 aio_mlockall $flags, $callback->($status) 1019 aio_mlockall $flags, $callback->($status)
983 Calls the "mlockall" function with the given $flags (a combination 1020 Calls the "mlockall" function with the given $flags (a combination
984 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). 1021 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1022 "IO::AIO::MCL_ONFAULT").
985 1023
986 On systems that do not implement "mlockall", this function returns 1024 On systems that do not implement "mlockall", this function returns
987 -1 and sets errno to "ENOSYS". 1025 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1026 supported by the system result in a return value of -1 with errno
1027 being set to "EINVAL".
988 1028
989 Note that the corresponding "munlockall" is synchronous and is 1029 Note that the corresponding "munlockall" is synchronous and is
990 documented under "MISCELLANEOUS FUNCTIONS". 1030 documented under "MISCELLANEOUS FUNCTIONS".
991 1031
992 Example: asynchronously lock all current and future pages into 1032 Example: asynchronously lock all current and future pages into
… …
1034 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1074 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1035 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1075 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1036 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1076 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1037 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1077 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1038 1078
1039 At the time of this writing (Linux 3.2), this requets is unreliable 1079 At the time of this writing (Linux 3.2), this request is unreliable
1040 unless $count is "undef", as the kernel has all sorts of bugs 1080 unless $count is "undef", as the kernel has all sorts of bugs
1041 preventing it to return all extents of a range for files with large 1081 preventing it to return all extents of a range for files with a
1042 number of extents. The code works around all these issues if $count 1082 large number of extents. The code (only) works around all these
1043 is undef. 1083 issues if $count is "undef".
1044 1084
1045 aio_group $callback->(...) 1085 aio_group $callback->(...)
1046 This is a very special aio request: Instead of doing something, it 1086 This is a very special aio request: Instead of doing something, it
1047 is a container for other aio requests, which is useful if you want 1087 is a container for other aio requests, which is useful if you want
1048 to bundle many requests into a single, composite, request with a 1088 to bundle many requests into a single, composite, request with a
… …
1128 aio_stat [$etcdir, "passwd"], sub { 1168 aio_stat [$etcdir, "passwd"], sub {
1129 # yay 1169 # yay
1130 }; 1170 };
1131 }; 1171 };
1132 1172
1133 That "aio_wd" is a request and not a normal function shows that creating 1173 The fact that "aio_wd" is a request and not a normal function shows that
1134 an IO::AIO::WD object is itself a potentially blocking operation, which 1174 creating an IO::AIO::WD object is itself a potentially blocking
1135 is why it is done asynchronously. 1175 operation, which is why it is done asynchronously.
1136 1176
1137 To stat the directory obtained with "aio_wd" above, one could write 1177 To stat the directory obtained with "aio_wd" above, one could write
1138 either of the following three request calls: 1178 either of the following three request calls:
1139 1179
1140 aio_lstat "/etc" , sub { ... # pathname as normal string 1180 aio_lstat "/etc" , sub { ... # pathname as normal string
… …
1157 There are some caveats: when directories get renamed (or deleted), the 1197 There are some caveats: when directories get renamed (or deleted), the
1158 pathname string doesn't change, so will point to the new directory (or 1198 pathname string doesn't change, so will point to the new directory (or
1159 nowhere at all), while the directory fd, if available on the system, 1199 nowhere at all), while the directory fd, if available on the system,
1160 will still point to the original directory. Most functions accepting a 1200 will still point to the original directory. Most functions accepting a
1161 pathname will use the directory fd on newer systems, and the string on 1201 pathname will use the directory fd on newer systems, and the string on
1162 older systems. Some functions (such as realpath) will always rely on the 1202 older systems. Some functions (such as "aio_realpath") will always rely
1163 string form of the pathname. 1203 on the string form of the pathname.
1164 1204
1165 So this functionality is mainly useful to get some protection against 1205 So this functionality is mainly useful to get some protection against
1166 "chdir", to easily get an absolute path out of a relative path for 1206 "chdir", to easily get an absolute path out of a relative path for
1167 future reference, and to speed up doing many operations in the same 1207 future reference, and to speed up doing many operations in the same
1168 directory (e.g. when stat'ing all files in a directory). 1208 directory (e.g. when stat'ing all files in a directory).
… …
1416 Strictly equivalent to: 1456 Strictly equivalent to:
1417 1457
1418 IO::AIO::poll_wait, IO::AIO::poll_cb 1458 IO::AIO::poll_wait, IO::AIO::poll_cb
1419 while IO::AIO::nreqs; 1459 while IO::AIO::nreqs;
1420 1460
1461 This function can be useful at program aborts, to make sure
1462 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1463 already calls this function on normal exits), or when you are merely
1464 using "IO::AIO" for its more advanced functions, rather than for
1465 async I/O, e.g.:
1466
1467 my ($dirs, $nondirs);
1468 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1469 IO::AIO::flush;
1470 # $dirs, $nondirs are now set
1471
1421 IO::AIO::max_poll_reqs $nreqs 1472 IO::AIO::max_poll_reqs $nreqs
1422 IO::AIO::max_poll_time $seconds 1473 IO::AIO::max_poll_time $seconds
1423 These set the maximum number of requests (default 0, meaning 1474 These set the maximum number of requests (default 0, meaning
1424 infinity) that are being processed by "IO::AIO::poll_cb" in one 1475 infinity) that are being processed by "IO::AIO::poll_cb" in one
1425 call, respectively the maximum amount of time (default 0, meaning 1476 call, respectively the maximum amount of time (default 0, meaning
… …
1518 1569
1519 This is a very bad function to use in interactive programs because 1570 This is a very bad function to use in interactive programs because
1520 it blocks, and a bad way to reduce concurrency because it is 1571 it blocks, and a bad way to reduce concurrency because it is
1521 inexact: Better use an "aio_group" together with a feed callback. 1572 inexact: Better use an "aio_group" together with a feed callback.
1522 1573
1523 It's main use is in scripts without an event loop - when you want to 1574 Its main use is in scripts without an event loop - when you want to
1524 stat a lot of files, you can write somehting like this: 1575 stat a lot of files, you can write something like this:
1525 1576
1526 IO::AIO::max_outstanding 32; 1577 IO::AIO::max_outstanding 32;
1527 1578
1528 for my $path (...) { 1579 for my $path (...) {
1529 aio_stat $path , ...; 1580 aio_stat $path , ...;
… …
1558 1609
1559 IO::AIO::npending 1610 IO::AIO::npending
1560 Returns the number of requests currently in the pending state 1611 Returns the number of requests currently in the pending state
1561 (executed, but not yet processed by poll_cb). 1612 (executed, but not yet processed by poll_cb).
1562 1613
1614 SUBSECOND STAT TIME ACCESS
1615 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1616 generally find access/modification and change times with subsecond time
1617 accuracy of the system supports it, but perl's built-in functions only
1618 return the integer part.
1619
1620 The following functions return the timestamps of the most recent stat
1621 with subsecond precision on most systems and work both after
1622 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1623 value is only meaningful after a successful "stat"/"lstat" call, or
1624 during/after a successful "aio_stat"/"aio_lstat" callback.
1625
1626 This is similar to the Time::HiRes "stat" functions, but can return full
1627 resolution without rounding and work with standard perl "stat",
1628 alleviating the need to call the special "Time::HiRes" functions, which
1629 do not act like their perl counterparts.
1630
1631 On operating systems or file systems where subsecond time resolution is
1632 not supported or could not be detected, a fractional part of 0 is
1633 returned, so it is always safe to call these functions.
1634
1635 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1636 IO::AIO::st_btime
1637 Return the access, modication, change or birth time, respectively,
1638 including fractional part. Due to the limited precision of floating
1639 point, the accuracy on most platforms is only a bit better than
1640 milliseconds for times around now - see the *nsec* function family,
1641 below, for full accuracy.
1642
1643 File birth time is only available when the OS and perl support it
1644 (on FreeBSD and NetBSD at the time of this writing, although support
1645 is adaptive, so if your OS/perl gains support, IO::AIO can take
1646 avdantage of it). On systems where it isn't available, 0 is
1647 currently returned, but this might change to "undef" in a future
1648 version.
1649
1650 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1651 Returns access, modification, change and birth time all in one go,
1652 and maybe more times in the future version.
1653
1654 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1655 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1656 Return the fractional access, modifcation, change or birth time, in
1657 nanoseconds, as an integer in the range 0 to 999999999.
1658
1659 Note that no accessors are provided for access, modification and
1660 change times - you need to get those from "stat _" if required ("int
1661 IO::AIO::st_atime" and so on will *not* generally give you the
1662 correct value).
1663
1664 $seconds = IO::AIO::st_btimesec
1665 The (integral) seconds part of the file birth time, if available.
1666
1667 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1668 Like the functions above, but returns all four times in one go (and
1669 maybe more in future versions).
1670
1671 $counter = IO::AIO::st_gen
1672 Returns the generation counter (in practice this is just a random
1673 number) of the file. This is only available on platforms which have
1674 this member in their "struct stat" (most BSDs at the time of this
1675 writing) and generally only to the root usert. If unsupported, 0 is
1676 returned, but this might change to "undef" in a future version.
1677
1678 Example: print the high resolution modification time of /etc, using
1679 "stat", and "IO::AIO::aio_stat".
1680
1681 if (stat "/etc") {
1682 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1683 }
1684
1685 IO::AIO::aio_stat "/etc", sub {
1686 $_[0]
1687 and return;
1688
1689 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1690 };
1691
1692 IO::AIO::flush;
1693
1694 Output of the awbove on my system, showing reduced and full accuracy:
1695
1696 stat(/etc) mtime: 1534043702.020808
1697 aio_stat(/etc) mtime: 1534043702.020807792
1698
1563 MISCELLANEOUS FUNCTIONS 1699 MISCELLANEOUS FUNCTIONS
1564 IO::AIO implements some functions that might be useful, but are not 1700 IO::AIO implements some functions that are useful when you want to use
1565 asynchronous. 1701 some "Advanced I/O" function not available to in Perl, without going the
1702 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1703 counterpart.
1704
1705 $numfd = IO::AIO::get_fdlimit
1706 This function is *EXPERIMENTAL* and subject to change.
1707
1708 Tries to find the current file descriptor limit and returns it, or
1709 "undef" and sets $! in case of an error. The limit is one larger
1710 than the highest valid file descriptor number.
1711
1712 IO::AIO::min_fdlimit [$numfd]
1713 This function is *EXPERIMENTAL* and subject to change.
1714
1715 Try to increase the current file descriptor limit(s) to at least
1716 $numfd by changing the soft or hard file descriptor resource limit.
1717 If $numfd is missing, it will try to set a very high limit, although
1718 this is not recommended when you know the actual minimum that you
1719 require.
1720
1721 If the limit cannot be raised enough, the function makes a
1722 best-effort attempt to increase the limit as much as possible, using
1723 various tricks, while still failing. You can query the resulting
1724 limit using "IO::AIO::get_fdlimit".
1725
1726 If an error occurs, returns "undef" and sets $!, otherwise returns
1727 true.
1566 1728
1567 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1729 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1568 Calls the "eio_sendfile_sync" function, which is like 1730 Calls the "eio_sendfile_sync" function, which is like
1569 "aio_sendfile", but is blocking (this makes most sense if you know 1731 "aio_sendfile", but is blocking (this makes most sense if you know
1570 the input data is likely cached already and the output filehandle is 1732 the input data is likely cached already and the output filehandle is
… …
1587 details). The following advice constants are available: 1749 details). The following advice constants are available:
1588 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1750 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1589 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1751 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1590 "IO::AIO::MADV_DONTNEED". 1752 "IO::AIO::MADV_DONTNEED".
1591 1753
1754 If $offset is negative, counts from the end. If $length is negative,
1755 the remaining length of the $scalar is used. If possible, $length
1756 will be reduced to fit into the $scalar.
1757
1592 On systems that do not implement "posix_madvise", this function 1758 On systems that do not implement "posix_madvise", this function
1593 returns ENOSYS, otherwise the return value of "posix_madvise". 1759 returns ENOSYS, otherwise the return value of "posix_madvise".
1594 1760
1595 IO::AIO::mprotect $scalar, $offset, $len, $protect 1761 IO::AIO::mprotect $scalar, $offset, $len, $protect
1596 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1762 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1597 $scalar (see its manpage for details). The following protect 1763 $scalar (see its manpage for details). The following protect
1598 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1764 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1599 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1765 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1600 1766
1767 If $offset is negative, counts from the end. If $length is negative,
1768 the remaining length of the $scalar is used. If possible, $length
1769 will be reduced to fit into the $scalar.
1770
1601 On systems that do not implement "mprotect", this function returns 1771 On systems that do not implement "mprotect", this function returns
1602 ENOSYS, otherwise the return value of "mprotect". 1772 ENOSYS, otherwise the return value of "mprotect".
1603 1773
1604 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1774 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1605 Memory-maps a file (or anonymous memory range) and attaches it to 1775 Memory-maps a file (or anonymous memory range) and attaches it to
1606 the given $scalar, which will act like a string scalar. Returns true 1776 the given $scalar, which will act like a string scalar. Returns true
1607 on success, and false otherwise. 1777 on success, and false otherwise.
1608 1778
1779 The scalar must exist, but its contents do not matter - this means
1780 you cannot use a nonexistant array or hash element. When in doubt,
1781 "undef" the scalar first.
1782
1609 The only operations allowed on the scalar are "substr"/"vec" that 1783 The only operations allowed on the mmapped scalar are
1610 don't change the string length, and most read-only operations such 1784 "substr"/"vec", which don't change the string length, and most
1611 as copying it or searching it with regexes and so on. 1785 read-only operations such as copying it or searching it with regexes
1786 and so on.
1612 1787
1613 Anything else is unsafe and will, at best, result in memory leaks. 1788 Anything else is unsafe and will, at best, result in memory leaks.
1614 1789
1615 The memory map associated with the $scalar is automatically removed 1790 The memory map associated with the $scalar is automatically removed
1616 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1791 when the $scalar is undef'd or destroyed, or when the
1617 "IO::AIO::munmap" functions are called. 1792 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1618 1793
1619 This calls the "mmap"(2) function internally. See your system's 1794 This calls the "mmap"(2) function internally. See your system's
1620 manual page for details on the $length, $prot and $flags parameters. 1795 manual page for details on the $length, $prot and $flags parameters.
1621 1796
1622 The $length must be larger than zero and smaller than the actual 1797 The $length must be larger than zero and smaller than the actual
… …
1626 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1801 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1627 "IO::AIO::PROT_WRITE", 1802 "IO::AIO::PROT_WRITE",
1628 1803
1629 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1804 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1630 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1805 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1631 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1806 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1632 (which is set to "MAP_ANON" if your system only provides this 1807 "MAP_ANON" if your system only provides this constant),
1808 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1633 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1809 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1810 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1634 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1811 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1635 "IO::AIO::MAP_NONBLOCK" 1812 "IO::AIO::MAP_STACK".
1636 1813
1637 If $fh is "undef", then a file descriptor of -1 is passed. 1814 If $fh is "undef", then a file descriptor of -1 is passed.
1638 1815
1639 $offset is the offset from the start of the file - it generally must 1816 $offset is the offset from the start of the file - it generally must
1640 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1817 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1652 1829
1653 my $fast_md5 = md5 $data; 1830 my $fast_md5 = md5 $data;
1654 1831
1655 IO::AIO::munmap $scalar 1832 IO::AIO::munmap $scalar
1656 Removes a previous mmap and undefines the $scalar. 1833 Removes a previous mmap and undefines the $scalar.
1834
1835 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1836 $new_address = 0]
1837 Calls the Linux-specific mremap(2) system call. The $scalar must
1838 have been mapped by "IO::AIO::mmap", and $flags must currently
1839 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1840
1841 Returns true if successful, and false otherwise. If the underlying
1842 mmapped region has changed address, then the true value has the
1843 numerical value 1, otherwise it has the numerical value 0:
1844
1845 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1846 or die "mremap: $!";
1847
1848 if ($success*1) {
1849 warn "scalar has chanegd address in memory\n";
1850 }
1851
1852 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1853 implemented, but not supported and might go away in a future
1854 version.
1855
1856 On systems where this call is not supported or is not emulated, this
1857 call returns falls and sets $! to "ENOSYS".
1858
1859 IO::AIO::mlockall $flags
1860 Calls the "eio_mlockall_sync" function, which is like
1861 "aio_mlockall", but is blocking.
1657 1862
1658 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1863 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1659 Calls the "munlock" function, undoing the effects of a previous 1864 Calls the "munlock" function, undoing the effects of a previous
1660 "aio_mlock" call (see its description for details). 1865 "aio_mlock" call (see its description for details).
1661 1866
… …
1678 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT". 1883 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1679 1884
1680 See the splice(2) manpage for details. 1885 See the splice(2) manpage for details.
1681 1886
1682 IO::AIO::tee $r_fh, $w_fh, $length, $flags 1887 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1683 Calls the GNU/Linux tee(2) syscall, see it's manpage and the 1888 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1684 description for "IO::AIO::splice" above for details. 1889 description for "IO::AIO::splice" above for details.
1685 1890
1686 $actual_size = IO::AIO::pipesize $r_fh[, $new_size] 1891 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1687 Attempts to query or change the pipe buffer size. Obviously works 1892 Attempts to query or change the pipe buffer size. Obviously works
1688 only on pipes, and currently works only on GNU/Linux systems, and 1893 only on pipes, and currently works only on GNU/Linux systems, and
1689 fails with -1/"ENOSYS" everywhere else. If anybody knows how to 1894 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1690 influence pipe buffer size on other systems, drop me a note. 1895 influence pipe buffer size on other systems, drop me a note.
1896
1897 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1898 This is a direct interface to the Linux pipe2(2) system call. If
1899 $flags is missing or 0, then this should be the same as a call to
1900 perl's built-in "pipe" function and create a new pipe, and works on
1901 systems that lack the pipe2 syscall. On win32, this case invokes
1902 "_pipe (..., 4096, O_BINARY)".
1903
1904 If $flags is non-zero, it tries to invoke the pipe2 system call with
1905 the given flags (Linux 2.6.27, glibc 2.9).
1906
1907 On success, the read and write file handles are returned.
1908
1909 On error, nothing will be returned. If the pipe2 syscall is missing
1910 and $flags is non-zero, fails with "ENOSYS".
1911
1912 Please refer to pipe2(2) for more info on the $flags, but at the
1913 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1914 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1915 supported.
1916
1917 Example: create a pipe race-free w.r.t. threads and fork:
1918
1919 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1920 or die "pipe2: $!\n";
1921
1922 $fh = IO::AIO::eventfd [$initval, [$flags]]
1923 This is a direct interface to the Linux eventfd(2) system call. The
1924 (unhelpful) defaults for $initval and $flags are 0 for both.
1925
1926 On success, the new eventfd filehandle is returned, otherwise
1927 returns "undef". If the eventfd syscall is missing, fails with
1928 "ENOSYS".
1929
1930 Please refer to eventfd(2) for more info on this call.
1931
1932 The following symbol flag values are available:
1933 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1934 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1935
1936 Example: create a new eventfd filehandle:
1937
1938 $fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC
1939 or die "eventfd: $!\n";
1940
1941 $fh = IO::AIO::timerfd_create $clockid[, $flags]
1942 This is a direct interface to the Linux timerfd_create(2) system
1943 call. The (unhelpful) default for $flags is 0.
1944
1945 On success, the new timerfd filehandle is returned, otherwise
1946 returns "undef". If the eventfd syscall is missing, fails with
1947 "ENOSYS".
1948
1949 Please refer to timerfd_create(2) for more info on this call.
1950
1951 The following $clockid values are available:
1952 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
1953 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
1954 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
1955 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
1956
1957 The following $flags values are available (Linux 2.6.27):
1958 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
1959
1960 Example: create a new timerfd and set it to one-second repeated
1961 alarms, then wait for two alarms:
1962
1963 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
1964 or die "timerfd_create: $!\n";
1965
1966 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
1967 or die "timerfd_settime: $!\n";
1968
1969 for (1..2) {
1970 8 == sysread $fh, my $buf, 8
1971 or die "timerfd read failure\n";
1972
1973 printf "number of expirations (likely 1): %d\n",
1974 unpack "Q", $buf;
1975 }
1976
1977 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
1978 $new_interval, $nbw_value
1979 This is a direct interface to the Linux timerfd_settime(2) system
1980 call. Please refer to its manpage for more info on this call.
1981
1982 The new itimerspec is specified using two (possibly fractional)
1983 second values, $new_interval and $new_value).
1984
1985 On success, the current interval and value are returned (as per
1986 "timerfd_gettime"). On failure, the empty list is returned.
1987
1988 The following $flags values are available:
1989 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
1990
1991 See "IO::AIO::timerfd_create" for a full example.
1992
1993 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
1994 This is a direct interface to the Linux timerfd_gettime(2) system
1995 call. Please refer to its manpage for more info on this call.
1996
1997 On success, returns the current values of interval and value for the
1998 given timerfd (as potentially fractional second values). On failure,
1999 the empty list is returned.
1691 2000
1692EVENT LOOP INTEGRATION 2001EVENT LOOP INTEGRATION
1693 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2002 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1694 automatically into many event loops: 2003 automatically into many event loops:
1695 2004
… …
1745 forking, if "IO::AIO" was used in the parent. Calling it while 2054 forking, if "IO::AIO" was used in the parent. Calling it while
1746 IO::AIO is active in the process will result in undefined behaviour. 2055 IO::AIO is active in the process will result in undefined behaviour.
1747 Calling it at any time will also result in any undefined (by POSIX) 2056 Calling it at any time will also result in any undefined (by POSIX)
1748 behaviour. 2057 behaviour.
1749 2058
2059 LINUX-SPECIFIC CALLS
2060 When a call is documented as "linux-specific" then this means it
2061 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2062 availability and compatibility of such calls regardless of the platform
2063 it is compiled on, so platforms such as FreeBSD which often implement
2064 these calls will work. When in doubt, call them and see if they fail wth
2065 "ENOSYS".
2066
1750 MEMORY USAGE 2067 MEMORY USAGE
1751 Per-request usage: 2068 Per-request usage:
1752 2069
1753 Each aio request uses - depending on your architecture - around 100-200 2070 Each aio request uses - depending on your architecture - around 100-200
1754 bytes of memory. In addition, stat requests need a stat buffer (possibly 2071 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1764 In the execution phase, some aio requests require more memory for 2081 In the execution phase, some aio requests require more memory for
1765 temporary buffers, and each thread requires a stack and other data 2082 temporary buffers, and each thread requires a stack and other data
1766 structures (usually around 16k-128k, depending on the OS). 2083 structures (usually around 16k-128k, depending on the OS).
1767 2084
1768KNOWN BUGS 2085KNOWN BUGS
1769 Known bugs will be fixed in the next release. 2086 Known bugs will be fixed in the next release :)
2087
2088KNOWN ISSUES
2089 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2090 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2091 non-created hash slots or other scalars I didn't think of. It's best to
2092 avoid such and either use scalar variables or making sure that the
2093 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2094
2095 I am not sure anything can be done about this, so this is considered a
2096 known issue, rather than a bug.
1770 2097
1771SEE ALSO 2098SEE ALSO
1772 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2099 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1773 more natural syntax. 2100 more natural syntax.
1774 2101

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