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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
146 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
148 151
149FUNCTIONS 152FUNCTIONS
150 QUICK OVERVIEW 153 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 154 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 155 reference. See the following sections for function-by-function
153 documentation. 156 documentation.
154 157
155 aio_wd $pathname, $callback->($wd) 158 aio_wd $pathname, $callback->($wd)
156 aio_open $pathname, $flags, $mode, $callback->($fh) 159 aio_open $pathname, $flags, $mode, $callback->($fh)
157 aio_close $fh, $callback->($status) 160 aio_close $fh, $callback->($status)
165 aio_statvfs $fh_or_path, $callback->($statvfs) 168 aio_statvfs $fh_or_path, $callback->($statvfs)
166 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
167 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
168 aio_chmod $fh_or_path, $mode, $callback->($status) 171 aio_chmod $fh_or_path, $mode, $callback->($status)
169 aio_truncate $fh_or_path, $offset, $callback->($status) 172 aio_truncate $fh_or_path, $offset, $callback->($status)
173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
170 aio_unlink $pathname, $callback->($status) 175 aio_unlink $pathname, $callback->($status)
171 aio_mknod $pathname, $mode, $dev, $callback->($status) 176 aio_mknod $pathname, $mode, $dev, $callback->($status)
172 aio_link $srcpath, $dstpath, $callback->($status) 177 aio_link $srcpath, $dstpath, $callback->($status)
173 aio_symlink $srcpath, $dstpath, $callback->($status) 178 aio_symlink $srcpath, $dstpath, $callback->($status)
174 aio_readlink $pathname, $callback->($link) 179 aio_readlink $pathname, $callback->($link)
175 aio_realpath $pathname, $callback->($link) 180 aio_realpath $pathname, $callback->($path)
176 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
177 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
178 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
179 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
180 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
181 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
183 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) 189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
184 aio_load $pathname, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
185 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
186 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
187 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)
188 aio_sync $callback->($status) 196 aio_sync $callback->($status)
189 aio_syncfs $fh, $callback->($status) 197 aio_syncfs $fh, $callback->($status)
190 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
191 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
192 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
193 aio_pathsync $pathname, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
194 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
195 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
196 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
197 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
198 aio_group $callback->(...) 206 aio_group $callback->(...)
199 aio_nop $callback->() 207 aio_nop $callback->()
213 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
214 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
215 IO::AIO::nreqs 223 IO::AIO::nreqs
216 IO::AIO::nready 224 IO::AIO::nready
217 IO::AIO::npending 225 IO::AIO::npending
226 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
227 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
218 228
219 IO::AIO::sendfile $ofh, $ifh, $offset, $count 229 IO::AIO::sendfile $ofh, $ifh, $offset, $count
220 IO::AIO::fadvise $fh, $offset, $len, $advice 230 IO::AIO::fadvise $fh, $offset, $len, $advice
231 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
232 IO::AIO::munmap $scalar
233 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
221 IO::AIO::madvise $scalar, $offset, $length, $advice 234 IO::AIO::madvise $scalar, $offset, $length, $advice
222 IO::AIO::mprotect $scalar, $offset, $length, $protect 235 IO::AIO::mprotect $scalar, $offset, $length, $protect
223 IO::AIO::munlock $scalar, $offset = 0, $length = undef 236 IO::AIO::munlock $scalar, $offset = 0, $length = undef
224 IO::AIO::munlockall 237 IO::AIO::munlockall
225 238
293 Similar to "aioreq_pri", but subtracts the given value from the 306 Similar to "aioreq_pri", but subtracts the given value from the
294 current priority, so the effect is cumulative. 307 current priority, so the effect is cumulative.
295 308
296 aio_open $pathname, $flags, $mode, $callback->($fh) 309 aio_open $pathname, $flags, $mode, $callback->($fh)
297 Asynchronously open or create a file and call the callback with a 310 Asynchronously open or create a file and call the callback with a
298 newly created filehandle for the file. 311 newly created filehandle for the file (or "undef" in case of an
312 error).
299 313
300 The pathname passed to "aio_open" must be absolute. See API NOTES, 314 The pathname passed to "aio_open" must be absolute. See API NOTES,
301 above, for an explanation. 315 above, for an explanation.
302 316
303 The $flags argument is a bitmask. See the "Fcntl" module for a list. 317 The $flags argument is a bitmask. See the "Fcntl" module for a list.
326 "O_APPEND"), the following POSIX and non-POSIX constants are 340 "O_APPEND"), the following POSIX and non-POSIX constants are
327 available (missing ones on your system are, as usual, 0): 341 available (missing ones on your system are, as usual, 0):
328 342
329 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 343 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
330 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 344 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
331 "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".
332 347
333 aio_close $fh, $callback->($status) 348 aio_close $fh, $callback->($status)
334 Asynchronously close a file and call the callback with the result 349 Asynchronously close a file and call the callback with the result
335 code. 350 code.
336 351
366 381
367 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 382 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
368 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 383 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
369 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
370 $offset into the scalar given by $data and offset $dataoffset and 385 $offset into the scalar given by $data and offset $dataoffset and
371 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
372 error, just like the syscall). 387 -1 on error, just like the syscall).
373 388
374 "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
375 offset plus the actual number of bytes read. 390 offset plus the actual number of bytes read.
376 391
377 If $offset is undefined, then the current file descriptor offset 392 If $offset is undefined, then the current file descriptor offset
434 As native sendfile syscalls (as practically any non-POSIX interface 449 As native sendfile syscalls (as practically any non-POSIX interface
435 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
436 rather buggy on many systems, this implementation tries to work 451 rather buggy on many systems, this implementation tries to work
437 around some known bugs in Linux and FreeBSD kernels (probably 452 around some known bugs in Linux and FreeBSD kernels (probably
438 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
439 the return value of "aio_sendfile" - fewre bytes than expected might 454 the return value of "aio_sendfile" - fewer bytes than expected might
440 have been transferred. 455 have been transferred.
441 456
442 aio_readahead $fh,$offset,$length, $callback->($retval) 457 aio_readahead $fh,$offset,$length, $callback->($retval)
443 "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
444 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
448 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
449 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
450 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
451 is left unchanged. 466 is left unchanged.
452 467
453 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
454 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
455 similar effect. 470 similar effect.
456 471
457 aio_stat $fh_or_path, $callback->($status) 472 aio_stat $fh_or_path, $callback->($status)
458 aio_lstat $fh, $callback->($status) 473 aio_lstat $fh, $callback->($status)
474 back on traditional behaviour). 489 back on traditional behaviour).
475 490
476 "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",
477 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 492 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
478 "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".
479 497
480 Example: Print the length of /etc/passwd: 498 Example: Print the length of /etc/passwd:
481 499
482 aio_stat "/etc/passwd", sub { 500 aio_stat "/etc/passwd", sub {
483 $_[0] and die "stat failed: $!"; 501 $_[0] and die "stat failed: $!";
556 aio_chown "path", 0, undef; 574 aio_chown "path", 0, undef;
557 575
558 aio_truncate $fh_or_path, $offset, $callback->($status) 576 aio_truncate $fh_or_path, $offset, $callback->($status)
559 Works like truncate(2) or ftruncate(2). 577 Works like truncate(2) or ftruncate(2).
560 578
579 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
580 Allocates or frees disk space according to the $mode argument. See
581 the linux "fallocate" documentation for details.
582
583 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
584 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
585 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
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
593 The file system block size used by "fallocate" is presumably the
594 "f_bsize" returned by "statvfs", but different filesystems and
595 filetypes can dictate other limitations.
596
597 If "fallocate" isn't available or cannot be emulated (currently no
598 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
599
561 aio_chmod $fh_or_path, $mode, $callback->($status) 600 aio_chmod $fh_or_path, $mode, $callback->($status)
562 Works like perl's "chmod" function. 601 Works like perl's "chmod" function.
563 602
564 aio_unlink $pathname, $callback->($status) 603 aio_unlink $pathname, $callback->($status)
565 Asynchronously unlink (delete) a file and call the callback with the 604 Asynchronously unlink (delete) a file and call the callback with the
591 the callback. If an error occurs, nothing or undef gets passed to 630 the callback. If an error occurs, nothing or undef gets passed to
592 the callback. 631 the callback.
593 632
594 aio_realpath $pathname, $callback->($path) 633 aio_realpath $pathname, $callback->($path)
595 Asynchronously make the path absolute and resolve any symlinks in 634 Asynchronously make the path absolute and resolve any symlinks in
596 $path. The resulting path only consists of directories (Same as 635 $path. The resulting path only consists of directories (same as
597 Cwd::realpath). 636 Cwd::realpath).
598 637
599 This request can be used to get the absolute path of the current 638 This request can be used to get the absolute path of the current
600 working directory by passing it a path of . (a single dot). 639 working directory by passing it a path of . (a single dot).
601 640
602 aio_rename $srcpath, $dstpath, $callback->($status) 641 aio_rename $srcpath, $dstpath, $callback->($status)
603 Asynchronously rename the object at $srcpath to $dstpath, just as 642 Asynchronously rename the object at $srcpath to $dstpath, just as
604 rename(2) and call the callback with the result code. 643 rename(2) and call the callback with the result code.
644
645 On systems that support the AIO::WD working directory abstraction
646 natively, the case "[$wd, "."]" as $srcpath is specialcased -
647 instead of failing, "rename" is called on the absolute path of $wd.
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".
605 663
606 aio_mkdir $pathname, $mode, $callback->($status) 664 aio_mkdir $pathname, $mode, $callback->($status)
607 Asynchronously mkdir (create) a directory and call the callback with 665 Asynchronously mkdir (create) a directory and call the callback with
608 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
609 request is executed, so do not change your umask. 667 request is executed, so do not change your umask.
610 668
611 aio_rmdir $pathname, $callback->($status) 669 aio_rmdir $pathname, $callback->($status)
612 Asynchronously rmdir (delete) a directory and call the callback with 670 Asynchronously rmdir (delete) a directory and call the callback with
613 the result code. 671 the result code.
614 672
673 On systems that support the AIO::WD working directory abstraction
674 natively, the case "[$wd, "."]" is specialcased - instead of
675 failing, "rmdir" is called on the absolute path of $wd.
676
615 aio_readdir $pathname, $callback->($entries) 677 aio_readdir $pathname, $callback->($entries)
616 Unlike the POSIX call of the same name, "aio_readdir" reads an 678 Unlike the POSIX call of the same name, "aio_readdir" reads an
617 entire directory (i.e. opendir + readdir + closedir). The entries 679 entire directory (i.e. opendir + readdir + closedir). The entries
618 will not be sorted, and will NOT include the "." and ".." entries. 680 will not be sorted, and will NOT include the "." and ".." entries.
619 681
628 The flags are a combination of the following constants, ORed 690 The flags are a combination of the following constants, ORed
629 together (the flags will also be passed to the callback, possibly 691 together (the flags will also be passed to the callback, possibly
630 modified): 692 modified):
631 693
632 IO::AIO::READDIR_DENTS 694 IO::AIO::READDIR_DENTS
633 When this flag is off, then the callback gets an arrayref 695 Normally the callback gets an arrayref consisting of names only
634 consisting of names only (as with "aio_readdir"), otherwise it 696 (as with "aio_readdir"). If this flag is set, then the callback
635 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 697 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
636 describing a single directory entry in more detail. 698 describing a single directory entry in more detail:
637 699
638 $name is the name of the entry. 700 $name is the name of the entry.
639 701
640 $type is one of the "IO::AIO::DT_xxx" constants: 702 $type is one of the "IO::AIO::DT_xxx" constants:
641 703
642 "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",
643 "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",
644 "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".
645 707
646 "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
647 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
648 reasons, the $type scalars are read-only: you can not modify 710 speed/memory reasons, the $type scalars are read-only: you must
649 them. 711 not modify them.
650 712
651 $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
652 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
653 unspecified content on systems that do not deliver the inode 715 unspecified content on systems that do not deliver the inode
654 information. 716 information.
666 of which names with short names are tried first. 728 of which names with short names are tried first.
667 729
668 IO::AIO::READDIR_STAT_ORDER 730 IO::AIO::READDIR_STAT_ORDER
669 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
670 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
671 to stat() all files in the given directory, then the returned 733 to stat() most or all files in the given directory, then the
672 order will likely be fastest. 734 returned order will likely be faster.
673 735
674 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 736 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
675 specified, then the likely dirs come first, resulting in a less 737 specified, then the likely dirs come first, resulting in a less
676 optimal stat order. 738 optimal stat order for stat'ing all entries, but likely a more
739 optimal order for finding subdirectories.
677 740
678 IO::AIO::READDIR_FOUND_UNKNOWN 741 IO::AIO::READDIR_FOUND_UNKNOWN
679 This flag should not be set when calling "aio_readdirx". 742 This flag should not be set when calling "aio_readdirx".
680 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
681 $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
682 flag therefore indicates that all $type's are known, which can 745 flag therefore indicates that all $type's are known, which can
683 be used to speed up some algorithms. 746 be used to speed up some algorithms.
684 747
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
685 aio_load $pathname, $data, $callback->($status) 775 aio_load $pathname, $data, $callback->($status)
686 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
687 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.
688 781
689 aio_copy $srcpath, $dstpath, $callback->($status) 782 aio_copy $srcpath, $dstpath, $callback->($status)
690 Try to copy the *file* (directories not supported as either source 783 Try to copy the *file* (directories not supported as either source
691 or destination) from $srcpath to $dstpath and call the callback with 784 or destination) from $srcpath to $dstpath and call the callback with
692 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.
693 788
694 This is a composite request that creates the destination file with 789 This is a composite request that creates the destination file with
695 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
696 "aio_sendfile", followed by restoring atime, mtime, access mode and 791 "aio_sendfile", followed by restoring atime, mtime, access mode and
697 uid/gid, in that order. 792 uid/gid, in that order.
714 to efficiently separate the entries of directory $path into two sets 809 to efficiently separate the entries of directory $path into two sets
715 of names, directories you can recurse into (directories), and ones 810 of names, directories you can recurse into (directories), and ones
716 you cannot recurse into (everything else, including symlinks to 811 you cannot recurse into (everything else, including symlinks to
717 directories). 812 directories).
718 813
719 "aio_scandir" is a composite request that creates of many sub 814 "aio_scandir" is a composite request that generates many sub
720 requests_ $maxreq specifies the maximum number of outstanding aio 815 requests. $maxreq specifies the maximum number of outstanding aio
721 requests that this function generates. If it is "<= 0", then a 816 requests that this function generates. If it is "<= 0", then a
722 suitable default will be chosen (currently 4). 817 suitable default will be chosen (currently 4).
723 818
724 On error, the callback is called without arguments, otherwise it 819 On error, the callback is called without arguments, otherwise it
725 receives two array-refs with path-relative entry names. 820 receives two array-refs with path-relative entry names.
772 Delete a directory tree starting (and including) $path, return the 867 Delete a directory tree starting (and including) $path, return the
773 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
774 uses "aio_scandir" to recurse into and rmdir directories, and unlink 869 uses "aio_scandir" to recurse into and rmdir directories, and unlink
775 everything else. 870 everything else.
776 871
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
777 aio_sync $callback->($status) 920 aio_sync $callback->($status)
778 Asynchronously call sync and call the callback when finished. 921 Asynchronously call sync and call the callback when finished.
779 922
780 aio_fsync $fh, $callback->($status) 923 aio_fsync $fh, $callback->($status)
781 Asynchronously call fsync on the given filehandle and call the 924 Asynchronously call fsync on the given filehandle and call the
817 Future versions of this function might fall back to other methods 960 Future versions of this function might fall back to other methods
818 when "fsync" on the directory fails (such as calling "sync"). 961 when "fsync" on the directory fails (such as calling "sync").
819 962
820 Passes 0 when everything went ok, and -1 on error. 963 Passes 0 when everything went ok, and -1 on error.
821 964
822 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 965 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
823 $callback->($status) 966 $callback->($status)
824 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
825 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
826 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,
827 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
829 972
830 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
831 memory area starting at $offset in the string and ending $length 974 memory area starting at $offset in the string and ending $length
832 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
833 $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
834 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
835 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 978 an optional "IO::AIO::MS_INVALIDATE".
836 979
837 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 980 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
838 $callback->($status) 981 $callback->($status)
839 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
840 mmap(2)ed scalars. 983 mmap(2)ed scalars.
841 984
842 It touches (reads or writes) all memory pages in the specified range 985 It touches (reads or writes) all memory pages in the specified range
843 inside the scalar. All caveats and parameters are the same as for 986 inside the scalar. All caveats and parameters are the same as for
844 "aio_msync", above, except for flags, which must be either 0 (which 987 "aio_msync", above, except for flags, which must be either 0 (which
845 reads all pages and ensures they are instantiated) or 988 reads all pages and ensures they are instantiated) or
846 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 989 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
847 and writing an octet from it, which dirties the page). 990 and writing an octet from it, which dirties the page).
848 991
849 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 992 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
850 This is a rather advanced IO::AIO call, which works best on 993 This is a rather advanced IO::AIO call, which works best on
851 mmap(2)ed scalars. 994 mmap(2)ed scalars.
885 memory. 1028 memory.
886 1029
887 aio_mlockall IO::AIO::MCL_FUTURE; 1030 aio_mlockall IO::AIO::MCL_FUTURE;
888 1031
889 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) 1032 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
890 Queries the extents of the given file (by calling the Linux FIEMAP 1033 Queries the extents of the given file (by calling the Linux "FIEMAP"
891 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for 1034 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
892 details). If the "ioctl" is not available on your OS, then this 1035 details). If the ioctl is not available on your OS, then this
893 rquiest will fail with "ENOSYS". 1036 request will fail with "ENOSYS".
894 1037
895 $start is the starting offset to query extents for, $length is the 1038 $start is the starting offset to query extents for, $length is the
896 size of the range to query - if it is "undef", then the whole file 1039 size of the range to query - if it is "undef", then the whole file
897 will be queried. 1040 will be queried.
898 1041
900 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is 1043 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
901 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to 1044 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
902 query the data portion. 1045 query the data portion.
903 1046
904 $count is the maximum number of extent records to return. If it is 1047 $count is the maximum number of extent records to return. If it is
905 "undef", then IO::AIO queries all extents of the file. As a very 1048 "undef", then IO::AIO queries all extents of the range. As a very
906 special case, if it is 0, then the callback receives the number of 1049 special case, if it is 0, then the callback receives the number of
907 extents instead of the extents themselves. 1050 extents instead of the extents themselves (which is unreliable, see
1051 below).
908 1052
909 If an error occurs, the callback receives no arguments. The special 1053 If an error occurs, the callback receives no arguments. The special
910 "errno" value "IO::AIO::EBADR" is available to test for flag errors. 1054 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
911 1055
912 Otherwise, the callback receives an array reference with extent 1056 Otherwise, the callback receives an array reference with extent
914 the following members: 1058 the following members:
915 1059
916 [$logical, $physical, $length, $flags] 1060 [$logical, $physical, $length, $flags]
917 1061
918 Flags is any combination of the following flag values (typically 1062 Flags is any combination of the following flag values (typically
919 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST"): 1063 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
920 1064
921 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN", 1065 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
922 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED", 1066 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
923 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED", 1067 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
924 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED", 1068 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
925 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", 1069 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
926 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", 1070 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
927 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" 1071 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
928 or "IO::AIO::FIEMAP_EXTENT_SHARED". 1072 or "IO::AIO::FIEMAP_EXTENT_SHARED".
929 1073
1074 At the time of this writing (Linux 3.2), this request is unreliable
1075 unless $count is "undef", as the kernel has all sorts of bugs
1076 preventing it to return all extents of a range for files with a
1077 large number of extents. The code (only) works around all these
1078 issues if $count is "undef".
1079
930 aio_group $callback->(...) 1080 aio_group $callback->(...)
931 This is a very special aio request: Instead of doing something, it 1081 This is a very special aio request: Instead of doing something, it
932 is a container for other aio requests, which is useful if you want 1082 is a container for other aio requests, which is useful if you want
933 to bundle many requests into a single, composite, request with a 1083 to bundle many requests into a single, composite, request with a
934 definite callback and the ability to cancel the whole request with 1084 definite callback and the ability to cancel the whole request with
1013 aio_stat [$etcdir, "passwd"], sub { 1163 aio_stat [$etcdir, "passwd"], sub {
1014 # yay 1164 # yay
1015 }; 1165 };
1016 }; 1166 };
1017 1167
1018 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
1019 an IO::AIO::WD object is itself a potentially blocking operation, which 1169 creating an IO::AIO::WD object is itself a potentially blocking
1020 is why it is done asynchronously. 1170 operation, which is why it is done asynchronously.
1021 1171
1022 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
1023 either of the following three request calls: 1173 either of the following three request calls:
1024 1174
1025 aio_lstat "/etc" , sub { ... # pathname as normal string 1175 aio_lstat "/etc" , sub { ... # pathname as normal string
1042 There are some caveats: when directories get renamed (or deleted), the 1192 There are some caveats: when directories get renamed (or deleted), the
1043 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
1044 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,
1045 will still point to the original directory. Most functions accepting a 1195 will still point to the original directory. Most functions accepting a
1046 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
1047 older systems. Some functions (such as realpath) will always rely on the 1197 older systems. Some functions (such as "aio_realpath") will always rely
1048 string form of the pathname. 1198 on the string form of the pathname.
1049 1199
1050 So this fucntionality is mainly useful to get some protection against 1200 So this functionality is mainly useful to get some protection against
1051 "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
1052 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
1053 directory (e.g. when stat'ing all files in a directory). 1203 directory (e.g. when stat'ing all files in a directory).
1054 1204
1055 The following functions implement this working directory abstraction: 1205 The following functions implement this working directory abstraction:
1065 Since passing "undef" as working directory component of a pathname 1215 Since passing "undef" as working directory component of a pathname
1066 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
1067 checking in the "aio_wd" callback, as future requests using the 1217 checking in the "aio_wd" callback, as future requests using the
1068 value will fail in the expected way. 1218 value will fail in the expected way.
1069 1219
1070 If this call isn't available because your OS lacks it or it couldn't
1071 be detected, it will be emulated by calling "fsync" instead.
1072
1073 IO::AIO::CWD 1220 IO::AIO::CWD
1074 This is a compiletime constant (object) that represents the process 1221 This is a compiletime constant (object) that represents the process
1075 current working directory. 1222 current working directory.
1076 1223
1077 Specifying this object as working directory object for a pathname is 1224 Specifying this object as working directory object for a pathname is
1078 as if the pathname would be specified directly, without a directory 1225 as if the pathname would be specified directly, without a directory
1079 object, e.g., these calls are functionally identical: 1226 object. For example, these calls are functionally identical:
1080 1227
1081 aio_stat "somefile", sub { ... }; 1228 aio_stat "somefile", sub { ... };
1082 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1229 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1230
1231 To recover the path associated with an IO::AIO::WD object, you can use
1232 "aio_realpath":
1233
1234 aio_realpath $wd, sub {
1235 warn "path is $_[0]\n";
1236 };
1237
1238 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1239 sometimes, fall back to using an absolue path.
1083 1240
1084 IO::AIO::REQ CLASS 1241 IO::AIO::REQ CLASS
1085 All non-aggregate "aio_*" functions return an object of this class when 1242 All non-aggregate "aio_*" functions return an object of this class when
1086 called in non-void context. 1243 called in non-void context.
1087 1244
1239 results. 1396 results.
1240 1397
1241 See "poll_cb" for an example. 1398 See "poll_cb" for an example.
1242 1399
1243 IO::AIO::poll_cb 1400 IO::AIO::poll_cb
1244 Process some outstanding events on the result pipe. You have to call 1401 Process some requests that have reached the result phase (i.e. they
1402 have been executed but the results are not yet reported). You have
1403 to call this "regularly" to finish outstanding requests.
1404
1245 this regularly. Returns 0 if all events could be processed (or there 1405 Returns 0 if all events could be processed (or there were no events
1246 were no events to process), or -1 if it returned earlier for 1406 to process), or -1 if it returned earlier for whatever reason.
1247 whatever reason. Returns immediately when no events are outstanding. 1407 Returns immediately when no events are outstanding. The amount of
1248 The amount of events processed depends on the settings of 1408 events processed depends on the settings of "IO::AIO::max_poll_req",
1249 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1409 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1250 1410
1251 If not all requests were processed for whatever reason, the 1411 If not all requests were processed for whatever reason, the poll
1252 filehandle will still be ready when "poll_cb" returns, so normally 1412 file descriptor will still be ready when "poll_cb" returns, so
1253 you don't have to do anything special to have it called later. 1413 normally you don't have to do anything special to have it called
1414 later.
1254 1415
1255 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1416 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1256 becomes ready, it can be beneficial to call this function from loops 1417 becomes ready, it can be beneficial to call this function from loops
1257 which submit a lot of requests, to make sure the results get 1418 which submit a lot of requests, to make sure the results get
1258 processed when they become available and not just when the loop is 1419 processed when they become available and not just when the loop is
1266 Event->io (fd => IO::AIO::poll_fileno, 1427 Event->io (fd => IO::AIO::poll_fileno,
1267 poll => 'r', async => 1, 1428 poll => 'r', async => 1,
1268 cb => \&IO::AIO::poll_cb); 1429 cb => \&IO::AIO::poll_cb);
1269 1430
1270 IO::AIO::poll_wait 1431 IO::AIO::poll_wait
1271 If there are any outstanding requests and none of them in the result 1432 Wait until either at least one request is in the result phase or no
1272 phase, wait till the result filehandle becomes ready for reading 1433 requests are outstanding anymore.
1273 (simply does a "select" on the filehandle. This is useful if you 1434
1274 want to synchronously wait for some requests to finish). 1435 This is useful if you want to synchronously wait for some requests
1436 to become ready, without actually handling them.
1275 1437
1276 See "nreqs" for an example. 1438 See "nreqs" for an example.
1277 1439
1278 IO::AIO::poll 1440 IO::AIO::poll
1279 Waits until some requests have been handled. 1441 Waits until some requests have been handled.
1391 1553
1392 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
1393 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
1394 inexact: Better use an "aio_group" together with a feed callback. 1556 inexact: Better use an "aio_group" together with a feed callback.
1395 1557
1396 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
1397 stat a lot of files, you can write somehting like this: 1559 stat a lot of files, you can write something like this:
1398 1560
1399 IO::AIO::max_outstanding 32; 1561 IO::AIO::max_outstanding 32;
1400 1562
1401 for my $path (...) { 1563 for my $path (...) {
1402 aio_stat $path , ...; 1564 aio_stat $path , ...;
1431 1593
1432 IO::AIO::npending 1594 IO::AIO::npending
1433 Returns the number of requests currently in the pending state 1595 Returns the number of requests currently in the pending state
1434 (executed, but not yet processed by poll_cb). 1596 (executed, but not yet processed by poll_cb).
1435 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
1436 MISCELLANEOUS FUNCTIONS 1660 MISCELLANEOUS FUNCTIONS
1437 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
1438 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.
1439 1689
1440 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1690 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1441 Calls the "eio_sendfile_sync" function, which is like 1691 Calls the "eio_sendfile_sync" function, which is like
1442 "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
1443 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
1460 details). The following advice constants are available: 1710 details). The following advice constants are available:
1461 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1711 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1462 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1712 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1463 "IO::AIO::MADV_DONTNEED". 1713 "IO::AIO::MADV_DONTNEED".
1464 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
1465 On systems that do not implement "posix_madvise", this function 1719 On systems that do not implement "posix_madvise", this function
1466 returns ENOSYS, otherwise the return value of "posix_madvise". 1720 returns ENOSYS, otherwise the return value of "posix_madvise".
1467 1721
1468 IO::AIO::mprotect $scalar, $offset, $len, $protect 1722 IO::AIO::mprotect $scalar, $offset, $len, $protect
1469 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1723 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1470 $scalar (see its manpage for details). The following protect 1724 $scalar (see its manpage for details). The following protect
1471 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1725 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1472 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1726 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1473 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
1474 On systems that do not implement "mprotect", this function returns 1732 On systems that do not implement "mprotect", this function returns
1475 ENOSYS, otherwise the return value of "mprotect". 1733 ENOSYS, otherwise the return value of "mprotect".
1476 1734
1477 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1735 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1478 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
1479 the given $scalar, which will act like a string scalar. 1737 the given $scalar, which will act like a string scalar. Returns true
1738 on success, and false otherwise.
1480 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
1481 The only operations allowed on the scalar are "substr"/"vec" that 1744 The only operations allowed on the mmapped scalar are
1482 don't change the string length, and most read-only operations such 1745 "substr"/"vec", which don't change the string length, and most
1483 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.
1484 1748
1485 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.
1486 1750
1487 The memory map associated with the $scalar is automatically removed 1751 The memory map associated with the $scalar is automatically removed
1488 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1752 when the $scalar is undef'd or destroyed, or when the
1489 "IO::AIO::munmap" functions are called. 1753 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1490 1754
1491 This calls the "mmap"(2) function internally. See your system's 1755 This calls the "mmap"(2) function internally. See your system's
1492 manual page for details on the $length, $prot and $flags parameters. 1756 manual page for details on the $length, $prot and $flags parameters.
1493 1757
1494 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
1498 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1762 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1499 "IO::AIO::PROT_WRITE", 1763 "IO::AIO::PROT_WRITE",
1500 1764
1501 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1765 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1502 "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
1503 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
1504 (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",
1505 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",
1506 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1772 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1507 "IO::AIO::MAP_NONBLOCK" 1773 "IO::AIO::MAP_STACK".
1508 1774
1509 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.
1510 1776
1511 $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
1512 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1778 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1524 1790
1525 my $fast_md5 = md5 $data; 1791 my $fast_md5 = md5 $data;
1526 1792
1527 IO::AIO::munmap $scalar 1793 IO::AIO::munmap $scalar
1528 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".
1529 1819
1530 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1820 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1531 Calls the "munlock" function, undoing the effects of a previous 1821 Calls the "munlock" function, undoing the effects of a previous
1532 "aio_mlock" call (see its description for details). 1822 "aio_mlock" call (see its description for details).
1533 1823
1540 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags 1830 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1541 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or 1831 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1542 $w_off are "undef", then "NULL" is passed for these, otherwise they 1832 $w_off are "undef", then "NULL" is passed for these, otherwise they
1543 should be the file offset. 1833 should be the file offset.
1544 1834
1835 $r_fh and $w_fh should not refer to the same file, as splice might
1836 silently corrupt the data in this case.
1837
1545 The following symbol flag values are available: 1838 The following symbol flag values are available:
1546 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK", 1839 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1547 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT". 1840 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1548 1841
1549 See the splice(2) manpage for details. 1842 See the splice(2) manpage for details.
1550 1843
1551 IO::AIO::tee $r_fh, $w_fh, $length, $flags 1844 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1552 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
1553 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.
1554 1957
1555EVENT LOOP INTEGRATION 1958EVENT LOOP INTEGRATION
1556 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1959 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1557 automatically into many event loops: 1960 automatically into many event loops:
1558 1961
1608 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
1609 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.
1610 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)
1611 behaviour. 2014 behaviour.
1612 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
1613 MEMORY USAGE 2024 MEMORY USAGE
1614 Per-request usage: 2025 Per-request usage:
1615 2026
1616 Each aio request uses - depending on your architecture - around 100-200 2027 Each aio request uses - depending on your architecture - around 100-200
1617 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
1627 In the execution phase, some aio requests require more memory for 2038 In the execution phase, some aio requests require more memory for
1628 temporary buffers, and each thread requires a stack and other data 2039 temporary buffers, and each thread requires a stack and other data
1629 structures (usually around 16k-128k, depending on the OS). 2040 structures (usually around 16k-128k, depending on the OS).
1630 2041
1631KNOWN BUGS 2042KNOWN BUGS
1632 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.
1633 2054
1634SEE ALSO 2055SEE ALSO
1635 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
1636 more natural syntax. 2057 more natural syntax.
1637 2058

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