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Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC vs.
Revision 1.57 by root, Mon Jan 18 11:53:09 2016 UTC

64 64
65 EXAMPLE 65 EXAMPLE
66 This is a simple example that uses the EV module and loads /etc/passwd 66 This is a simple example that uses the EV module and loads /etc/passwd
67 asynchronously: 67 asynchronously:
68 68
69 use Fcntl;
70 use EV; 69 use EV;
71 use IO::AIO; 70 use IO::AIO;
72 71
73 # register the IO::AIO callback with EV 72 # register the IO::AIO callback with EV
74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 73 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
91 90
92 # file contents now in $contents 91 # file contents now in $contents
93 print $contents; 92 print $contents;
94 93
95 # exit event loop and program 94 # exit event loop and program
96 EV::unloop; 95 EV::break;
97 }; 96 };
98 }; 97 };
99 98
100 # possibly queue up other requests, or open GUI windows, 99 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 100 # check for sockets etc. etc.
102 101
103 # process events as long as there are some: 102 # process events as long as there are some:
104 EV::loop; 103 EV::run;
105 104
106REQUEST ANATOMY AND LIFETIME 105REQUEST ANATOMY AND LIFETIME
107 Every "aio_*" function creates a request. which is a C data structure 106 Every "aio_*" function creates a request. which is a C data structure
108 not directly visible to Perl. 107 not directly visible to Perl.
109 108
146 the actual aio request is severed and calling its methods will 145 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 146 either do nothing or result in a runtime error).
148 147
149FUNCTIONS 148FUNCTIONS
150 QUICK OVERVIEW 149 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 150 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 151 reference. See the following sections for function-by-function
153 documentation. 152 documentation.
154 153
154 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 155 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 156 aio_close $fh, $callback->($status)
157 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 158 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 159 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 160 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 161 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 162 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 163 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 164 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 165 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 166 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 168 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status) 169 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
170 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168 aio_unlink $pathname, $callback->($status) 171 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 172 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 173 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 174 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 175 aio_readlink $pathname, $callback->($link)
176 aio_realpath $pathname, $callback->($path)
173 aio_rename $srcpath, $dstpath, $callback->($status) 177 aio_rename $srcpath, $dstpath, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status) 178 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status) 179 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries) 180 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 181 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 182 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 183 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180 aio_load $path, $data, $callback->($status) 185 aio_load $pathname, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status) 186 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status) 187 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status) 188 aio_rmtree $pathname, $callback->($status)
185 aio_sync $callback->($status) 189 aio_sync $callback->($status)
190 aio_syncfs $fh, $callback->($status)
186 aio_fsync $fh, $callback->($status) 191 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status) 192 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 193 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status) 194 aio_pathsync $pathname, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 195 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 196 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 197 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status) 198 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...) 199 aio_group $callback->(...)
212 IO::AIO::nready 217 IO::AIO::nready
213 IO::AIO::npending 218 IO::AIO::npending
214 219
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count 220 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice 221 IO::AIO::fadvise $fh, $offset, $len, $advice
222 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
223 IO::AIO::munmap $scalar
217 IO::AIO::madvise $scalar, $offset, $length, $advice 224 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect 225 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef 226 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall 227 IO::AIO::munlockall
221 228
222 AIO REQUEST FUNCTIONS 229 API NOTES
223 All the "aio_*" calls are more or less thin wrappers around the syscall 230 All the "aio_*" calls are more or less thin wrappers around the syscall
224 with the same name (sans "aio_"). The arguments are similar or 231 with the same name (sans "aio_"). The arguments are similar or
225 identical, and they all accept an additional (and optional) $callback 232 identical, and they all accept an additional (and optional) $callback
226 argument which must be a code reference. This code reference will get 233 argument which must be a code reference. This code reference will be
227 called with the syscall return code (e.g. most syscalls return -1 on
228 error, unlike perl, which usually delivers "false") as its sole argument
229 after the given syscall has been executed asynchronously. 234 called after the syscall has been executed in an asynchronous fashion.
235 The results of the request will be passed as arguments to the callback
236 (and, if an error occured, in $!) - for most requests the syscall return
237 code (e.g. most syscalls return -1 on error, unlike perl, which usually
238 delivers "false").
239
240 Some requests (such as "aio_readdir") pass the actual results and
241 communicate failures by passing "undef".
230 242
231 All functions expecting a filehandle keep a copy of the filehandle 243 All functions expecting a filehandle keep a copy of the filehandle
232 internally until the request has finished. 244 internally until the request has finished.
233 245
234 All functions return request objects of type IO::AIO::REQ that allow 246 All functions return request objects of type IO::AIO::REQ that allow
235 further manipulation of those requests while they are in-flight. 247 further manipulation of those requests while they are in-flight.
236 248
237 The pathnames you pass to these routines *must* be absolute and encoded 249 The pathnames you pass to these routines *should* be absolute. The
238 as octets. The reason for the former is that at the time the request is 250 reason for this is that at the time the request is being executed, the
239 being executed, the current working directory could have changed. 251 current working directory could have changed. Alternatively, you can
240 Alternatively, you can make sure that you never change the current 252 make sure that you never change the current working directory anywhere
241 working directory anywhere in the program and then use relative paths. 253 in the program and then use relative paths. You can also take advantage
254 of IO::AIOs working directory abstraction, that lets you specify paths
255 relative to some previously-opened "working directory object" - see the
256 description of the "IO::AIO::WD" class later in this document.
242 257
243 To encode pathnames as octets, either make sure you either: a) always 258 To encode pathnames as octets, either make sure you either: a) always
244 pass in filenames you got from outside (command line, readdir etc.) 259 pass in filenames you got from outside (command line, readdir etc.)
245 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 260 without tinkering, b) are in your native filesystem encoding, c) use the
246 and encode your pathnames to the locale (or other) encoding in effect in 261 Encode module and encode your pathnames to the locale (or other)
247 the user environment, d) use Glib::filename_from_unicode on unicode 262 encoding in effect in the user environment, d) use
248 filenames or e) use something else to ensure your scalar has the correct 263 Glib::filename_from_unicode on unicode filenames or e) use something
249 contents. 264 else to ensure your scalar has the correct contents.
250 265
251 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 266 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
252 handles correctly whether it is set or not. 267 handles correctly whether it is set or not.
253 268
269 AIO REQUEST FUNCTIONS
254 $prev_pri = aioreq_pri [$pri] 270 $prev_pri = aioreq_pri [$pri]
255 Returns the priority value that would be used for the next request 271 Returns the priority value that would be used for the next request
256 and, if $pri is given, sets the priority for the next aio request. 272 and, if $pri is given, sets the priority for the next aio request.
257 273
258 The default priority is 0, the minimum and maximum priorities are -4 274 The default priority is 0, the minimum and maximum priorities are -4
280 Similar to "aioreq_pri", but subtracts the given value from the 296 Similar to "aioreq_pri", but subtracts the given value from the
281 current priority, so the effect is cumulative. 297 current priority, so the effect is cumulative.
282 298
283 aio_open $pathname, $flags, $mode, $callback->($fh) 299 aio_open $pathname, $flags, $mode, $callback->($fh)
284 Asynchronously open or create a file and call the callback with a 300 Asynchronously open or create a file and call the callback with a
285 newly created filehandle for the file. 301 newly created filehandle for the file (or "undef" in case of an
302 error).
286 303
287 The pathname passed to "aio_open" must be absolute. See API NOTES, 304 The pathname passed to "aio_open" must be absolute. See API NOTES,
288 above, for an explanation. 305 above, for an explanation.
289 306
290 The $flags argument is a bitmask. See the "Fcntl" module for a list. 307 The $flags argument is a bitmask. See the "Fcntl" module for a list.
313 "O_APPEND"), the following POSIX and non-POSIX constants are 330 "O_APPEND"), the following POSIX and non-POSIX constants are
314 available (missing ones on your system are, as usual, 0): 331 available (missing ones on your system are, as usual, 0):
315 332
316 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 333 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
317 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 334 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
318 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". 335 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and
336 "O_TTY_INIT".
319 337
320 aio_close $fh, $callback->($status) 338 aio_close $fh, $callback->($status)
321 Asynchronously close a file and call the callback with the result 339 Asynchronously close a file and call the callback with the result
322 code. 340 code.
323 341
329 will use dup2 to overwrite the file descriptor with the write-end of 347 will use dup2 to overwrite the file descriptor with the write-end of
330 a pipe (the pipe fd will be created on demand and will be cached). 348 a pipe (the pipe fd will be created on demand and will be cached).
331 349
332 Or in other words: the file descriptor will be closed, but it will 350 Or in other words: the file descriptor will be closed, but it will
333 not be free for reuse until the perl filehandle is closed. 351 not be free for reuse until the perl filehandle is closed.
352
353 aio_seek $fh, $offset, $whence, $callback->($offs)
354 Seeks the filehandle to the new $offset, similarly to perl's
355 "sysseek". The $whence can use the traditional values (0 for
356 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
357 "IO::AIO::SEEK_END").
358
359 The resulting absolute offset will be passed to the callback, or -1
360 in case of an error.
361
362 In theory, the $whence constants could be different than the
363 corresponding values from Fcntl, but perl guarantees they are the
364 same, so don't panic.
365
366 As a GNU/Linux (and maybe Solaris) extension, also the constants
367 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
368 could be found. No guarantees about suitability for use in
369 "aio_seek" or Perl's "sysseek" can be made though, although I would
370 naively assume they "just work".
334 371
335 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 372 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
336 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 373 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
337 Reads or writes $length bytes from or to the specified $fh and 374 Reads or writes $length bytes from or to the specified $fh and
338 $offset into the scalar given by $data and offset $dataoffset and 375 $offset into the scalar given by $data and offset $dataoffset and
493 namemax => 255, 530 namemax => 255,
494 frsize => 1024, 531 frsize => 1024,
495 fsid => 1810 532 fsid => 1810
496 } 533 }
497 534
535 Here is a (likely partial - send me updates!) list of fsid values
536 used by Linux - it is safe to hardcode these when $^O is "linux":
537
538 0x0000adf5 adfs
539 0x0000adff affs
540 0x5346414f afs
541 0x09041934 anon-inode filesystem
542 0x00000187 autofs
543 0x42465331 befs
544 0x1badface bfs
545 0x42494e4d binfmt_misc
546 0x9123683e btrfs
547 0x0027e0eb cgroupfs
548 0xff534d42 cifs
549 0x73757245 coda
550 0x012ff7b7 coh
551 0x28cd3d45 cramfs
552 0x453dcd28 cramfs-wend (wrong endianness)
553 0x64626720 debugfs
554 0x00001373 devfs
555 0x00001cd1 devpts
556 0x0000f15f ecryptfs
557 0x00414a53 efs
558 0x0000137d ext
559 0x0000ef53 ext2/ext3/ext4
560 0x0000ef51 ext2
561 0xf2f52010 f2fs
562 0x00004006 fat
563 0x65735546 fuseblk
564 0x65735543 fusectl
565 0x0bad1dea futexfs
566 0x01161970 gfs2
567 0x47504653 gpfs
568 0x00004244 hfs
569 0xf995e849 hpfs
570 0x00c0ffee hostfs
571 0x958458f6 hugetlbfs
572 0x2bad1dea inotifyfs
573 0x00009660 isofs
574 0x000072b6 jffs2
575 0x3153464a jfs
576 0x6b414653 k-afs
577 0x0bd00bd0 lustre
578 0x0000137f minix
579 0x0000138f minix 30 char names
580 0x00002468 minix v2
581 0x00002478 minix v2 30 char names
582 0x00004d5a minix v3
583 0x19800202 mqueue
584 0x00004d44 msdos
585 0x0000564c novell
586 0x00006969 nfs
587 0x6e667364 nfsd
588 0x00003434 nilfs
589 0x5346544e ntfs
590 0x00009fa1 openprom
591 0x7461636F ocfs2
592 0x00009fa0 proc
593 0x6165676c pstorefs
594 0x0000002f qnx4
595 0x68191122 qnx6
596 0x858458f6 ramfs
597 0x52654973 reiserfs
598 0x00007275 romfs
599 0x67596969 rpc_pipefs
600 0x73636673 securityfs
601 0xf97cff8c selinux
602 0x0000517b smb
603 0x534f434b sockfs
604 0x73717368 squashfs
605 0x62656572 sysfs
606 0x012ff7b6 sysv2
607 0x012ff7b5 sysv4
608 0x01021994 tmpfs
609 0x15013346 udf
610 0x00011954 ufs
611 0x54190100 ufs byteswapped
612 0x00009fa2 usbdevfs
613 0x01021997 v9fs
614 0xa501fcf5 vxfs
615 0xabba1974 xenfs
616 0x012ff7b4 xenix
617 0x58465342 xfs
618 0x012fd16d xia
619
498 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 620 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
499 Works like perl's "utime" function (including the special case of 621 Works like perl's "utime" function (including the special case of
500 $atime and $mtime being undef). Fractional times are supported if 622 $atime and $mtime being undef). Fractional times are supported if
501 the underlying syscalls support them. 623 the underlying syscalls support them.
502 624
524 aio_chown "path", 0, undef; 646 aio_chown "path", 0, undef;
525 647
526 aio_truncate $fh_or_path, $offset, $callback->($status) 648 aio_truncate $fh_or_path, $offset, $callback->($status)
527 Works like truncate(2) or ftruncate(2). 649 Works like truncate(2) or ftruncate(2).
528 650
651 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
652 Allocates or frees disk space according to the $mode argument. See
653 the linux "fallocate" documentation for details.
654
655 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
656 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
657 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
658
659 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
660 (without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range
661 (see your fallocate(2) manpage).
662
663 The file system block size used by "fallocate" is presumably the
664 "f_bsize" returned by "statvfs".
665
666 If "fallocate" isn't available or cannot be emulated (currently no
667 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
668
529 aio_chmod $fh_or_path, $mode, $callback->($status) 669 aio_chmod $fh_or_path, $mode, $callback->($status)
530 Works like perl's "chmod" function. 670 Works like perl's "chmod" function.
531 671
532 aio_unlink $pathname, $callback->($status) 672 aio_unlink $pathname, $callback->($status)
533 Asynchronously unlink (delete) a file and call the callback with the 673 Asynchronously unlink (delete) a file and call the callback with the
534 result code. 674 result code.
535 675
536 aio_mknod $path, $mode, $dev, $callback->($status) 676 aio_mknod $pathname, $mode, $dev, $callback->($status)
537 [EXPERIMENTAL] 677 [EXPERIMENTAL]
538 678
539 Asynchronously create a device node (or fifo). See mknod(2). 679 Asynchronously create a device node (or fifo). See mknod(2).
540 680
541 The only (POSIX-) portable way of calling this function is: 681 The only (POSIX-) portable way of calling this function is:
542 682
543 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 683 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
544 684
545 See "aio_stat" for info about some potentially helpful extra 685 See "aio_stat" for info about some potentially helpful extra
546 constants and functions. 686 constants and functions.
547 687
548 aio_link $srcpath, $dstpath, $callback->($status) 688 aio_link $srcpath, $dstpath, $callback->($status)
552 aio_symlink $srcpath, $dstpath, $callback->($status) 692 aio_symlink $srcpath, $dstpath, $callback->($status)
553 Asynchronously create a new symbolic link to the existing object at 693 Asynchronously create a new symbolic link to the existing object at
554 $srcpath at the path $dstpath and call the callback with the result 694 $srcpath at the path $dstpath and call the callback with the result
555 code. 695 code.
556 696
557 aio_readlink $path, $callback->($link) 697 aio_readlink $pathname, $callback->($link)
558 Asynchronously read the symlink specified by $path and pass it to 698 Asynchronously read the symlink specified by $path and pass it to
559 the callback. If an error occurs, nothing or undef gets passed to 699 the callback. If an error occurs, nothing or undef gets passed to
560 the callback. 700 the callback.
561 701
702 aio_realpath $pathname, $callback->($path)
703 Asynchronously make the path absolute and resolve any symlinks in
704 $path. The resulting path only consists of directories (same as
705 Cwd::realpath).
706
707 This request can be used to get the absolute path of the current
708 working directory by passing it a path of . (a single dot).
709
562 aio_rename $srcpath, $dstpath, $callback->($status) 710 aio_rename $srcpath, $dstpath, $callback->($status)
563 Asynchronously rename the object at $srcpath to $dstpath, just as 711 Asynchronously rename the object at $srcpath to $dstpath, just as
564 rename(2) and call the callback with the result code. 712 rename(2) and call the callback with the result code.
713
714 On systems that support the AIO::WD working directory abstraction
715 natively, the case "[$wd, "."]" as $srcpath is specialcased -
716 instead of failing, "rename" is called on the absolute path of $wd.
565 717
566 aio_mkdir $pathname, $mode, $callback->($status) 718 aio_mkdir $pathname, $mode, $callback->($status)
567 Asynchronously mkdir (create) a directory and call the callback with 719 Asynchronously mkdir (create) a directory and call the callback with
568 the result code. $mode will be modified by the umask at the time the 720 the result code. $mode will be modified by the umask at the time the
569 request is executed, so do not change your umask. 721 request is executed, so do not change your umask.
570 722
571 aio_rmdir $pathname, $callback->($status) 723 aio_rmdir $pathname, $callback->($status)
572 Asynchronously rmdir (delete) a directory and call the callback with 724 Asynchronously rmdir (delete) a directory and call the callback with
573 the result code. 725 the result code.
574 726
727 On systems that support the AIO::WD working directory abstraction
728 natively, the case "[$wd, "."]" is specialcased - instead of
729 failing, "rmdir" is called on the absolute path of $wd.
730
575 aio_readdir $pathname, $callback->($entries) 731 aio_readdir $pathname, $callback->($entries)
576 Unlike the POSIX call of the same name, "aio_readdir" reads an 732 Unlike the POSIX call of the same name, "aio_readdir" reads an
577 entire directory (i.e. opendir + readdir + closedir). The entries 733 entire directory (i.e. opendir + readdir + closedir). The entries
578 will not be sorted, and will NOT include the "." and ".." entries. 734 will not be sorted, and will NOT include the "." and ".." entries.
579 735
580 The callback is passed a single argument which is either "undef" or 736 The callback is passed a single argument which is either "undef" or
581 an array-ref with the filenames. 737 an array-ref with the filenames.
582 738
583 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 739 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
584 Quite similar to "aio_readdir", but the $flags argument allows to 740 Quite similar to "aio_readdir", but the $flags argument allows one
585 tune behaviour and output format. In case of an error, $entries will 741 to tune behaviour and output format. In case of an error, $entries
586 be "undef". 742 will be "undef".
587 743
588 The flags are a combination of the following constants, ORed 744 The flags are a combination of the following constants, ORed
589 together (the flags will also be passed to the callback, possibly 745 together (the flags will also be passed to the callback, possibly
590 modified): 746 modified):
591 747
636 optimal stat order. 792 optimal stat order.
637 793
638 IO::AIO::READDIR_FOUND_UNKNOWN 794 IO::AIO::READDIR_FOUND_UNKNOWN
639 This flag should not be set when calling "aio_readdirx". 795 This flag should not be set when calling "aio_readdirx".
640 Instead, it is being set by "aio_readdirx", when any of the 796 Instead, it is being set by "aio_readdirx", when any of the
641 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 797 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
642 flag therefore indicates that all $type's are known, which can 798 flag therefore indicates that all $type's are known, which can
643 be used to speed up some algorithms. 799 be used to speed up some algorithms.
644 800
645 aio_load $path, $data, $callback->($status) 801 aio_load $pathname, $data, $callback->($status)
646 This is a composite request that tries to fully load the given file 802 This is a composite request that tries to fully load the given file
647 into memory. Status is the same as with aio_read. 803 into memory. Status is the same as with aio_read.
648 804
649 aio_copy $srcpath, $dstpath, $callback->($status) 805 aio_copy $srcpath, $dstpath, $callback->($status)
650 Try to copy the *file* (directories not supported as either source 806 Try to copy the *file* (directories not supported as either source
667 823
668 This is a composite request that tries to rename(2) the file first; 824 This is a composite request that tries to rename(2) the file first;
669 if rename fails with "EXDEV", it copies the file with "aio_copy" 825 if rename fails with "EXDEV", it copies the file with "aio_copy"
670 and, if that is successful, unlinks the $srcpath. 826 and, if that is successful, unlinks the $srcpath.
671 827
672 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 828 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
673 Scans a directory (similar to "aio_readdir") but additionally tries 829 Scans a directory (similar to "aio_readdir") but additionally tries
674 to efficiently separate the entries of directory $path into two sets 830 to efficiently separate the entries of directory $path into two sets
675 of names, directories you can recurse into (directories), and ones 831 of names, directories you can recurse into (directories), and ones
676 you cannot recurse into (everything else, including symlinks to 832 you cannot recurse into (everything else, including symlinks to
677 directories). 833 directories).
710 Then entries will be sorted into likely directories a non-initial 866 Then entries will be sorted into likely directories a non-initial
711 dot currently) and likely non-directories (see "aio_readdirx"). Then 867 dot currently) and likely non-directories (see "aio_readdirx"). Then
712 every entry plus an appended "/." will be "stat"'ed, likely 868 every entry plus an appended "/." will be "stat"'ed, likely
713 directories first, in order of their inode numbers. If that 869 directories first, in order of their inode numbers. If that
714 succeeds, it assumes that the entry is a directory or a symlink to 870 succeeds, it assumes that the entry is a directory or a symlink to
715 directory (which will be checked seperately). This is often faster 871 directory (which will be checked separately). This is often faster
716 than stat'ing the entry itself because filesystems might detect the 872 than stat'ing the entry itself because filesystems might detect the
717 type of the entry without reading the inode data (e.g. ext2fs 873 type of the entry without reading the inode data (e.g. ext2fs
718 filetype feature), even on systems that cannot return the filetype 874 filetype feature), even on systems that cannot return the filetype
719 information on readdir. 875 information on readdir.
720 876
726 882
727 It will also likely work on non-POSIX filesystems with reduced 883 It will also likely work on non-POSIX filesystems with reduced
728 efficiency as those tend to return 0 or 1 as link counts, which 884 efficiency as those tend to return 0 or 1 as link counts, which
729 disables the directory counting heuristic. 885 disables the directory counting heuristic.
730 886
731 aio_rmtree $path, $callback->($status) 887 aio_rmtree $pathname, $callback->($status)
732 Delete a directory tree starting (and including) $path, return the 888 Delete a directory tree starting (and including) $path, return the
733 status of the final "rmdir" only. This is a composite request that 889 status of the final "rmdir" only. This is a composite request that
734 uses "aio_scandir" to recurse into and rmdir directories, and unlink 890 uses "aio_scandir" to recurse into and rmdir directories, and unlink
735 everything else. 891 everything else.
736 892
745 Asynchronously call fdatasync on the given filehandle and call the 901 Asynchronously call fdatasync on the given filehandle and call the
746 callback with the fdatasync result code. 902 callback with the fdatasync result code.
747 903
748 If this call isn't available because your OS lacks it or it couldn't 904 If this call isn't available because your OS lacks it or it couldn't
749 be detected, it will be emulated by calling "fsync" instead. 905 be detected, it will be emulated by calling "fsync" instead.
906
907 aio_syncfs $fh, $callback->($status)
908 Asynchronously call the syncfs syscall to sync the filesystem
909 associated to the given filehandle and call the callback with the
910 syncfs result code. If syncfs is not available, calls sync(), but
911 returns -1 and sets errno to "ENOSYS" nevertheless.
750 912
751 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 913 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
752 Sync the data portion of the file specified by $offset and $length 914 Sync the data portion of the file specified by $offset and $length
753 to disk (but NOT the metadata), by calling the Linux-specific 915 to disk (but NOT the metadata), by calling the Linux-specific
754 sync_file_range call. If sync_file_range is not available or it 916 sync_file_range call. If sync_file_range is not available or it
758 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 920 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
759 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 921 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
760 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 922 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
761 manpage for details. 923 manpage for details.
762 924
763 aio_pathsync $path, $callback->($status) 925 aio_pathsync $pathname, $callback->($status)
764 This request tries to open, fsync and close the given path. This is 926 This request tries to open, fsync and close the given path. This is
765 a composite request intended to sync directories after directory 927 a composite request intended to sync directories after directory
766 operations (E.g. rename). This might not work on all operating 928 operations (E.g. rename). This might not work on all operating
767 systems or have any specific effect, but usually it makes sure that 929 systems or have any specific effect, but usually it makes sure that
768 directory changes get written to disc. It works for anything that 930 directory changes get written to disc. It works for anything that
795 957
796 It touches (reads or writes) all memory pages in the specified range 958 It touches (reads or writes) all memory pages in the specified range
797 inside the scalar. All caveats and parameters are the same as for 959 inside the scalar. All caveats and parameters are the same as for
798 "aio_msync", above, except for flags, which must be either 0 (which 960 "aio_msync", above, except for flags, which must be either 0 (which
799 reads all pages and ensures they are instantiated) or 961 reads all pages and ensures they are instantiated) or
800 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 962 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
801 and writing an octet from it, which dirties the page). 963 and writing an octet from it, which dirties the page).
802 964
803 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 965 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
804 This is a rather advanced IO::AIO call, which works best on 966 This is a rather advanced IO::AIO call, which works best on
805 mmap(2)ed scalars. 967 mmap(2)ed scalars.
837 999
838 Example: asynchronously lock all current and future pages into 1000 Example: asynchronously lock all current and future pages into
839 memory. 1001 memory.
840 1002
841 aio_mlockall IO::AIO::MCL_FUTURE; 1003 aio_mlockall IO::AIO::MCL_FUTURE;
1004
1005 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1006 Queries the extents of the given file (by calling the Linux "FIEMAP"
1007 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1008 details). If the ioctl is not available on your OS, then this
1009 request will fail with "ENOSYS".
1010
1011 $start is the starting offset to query extents for, $length is the
1012 size of the range to query - if it is "undef", then the whole file
1013 will be queried.
1014
1015 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1016 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1017 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1018 query the data portion.
1019
1020 $count is the maximum number of extent records to return. If it is
1021 "undef", then IO::AIO queries all extents of the range. As a very
1022 special case, if it is 0, then the callback receives the number of
1023 extents instead of the extents themselves (which is unreliable, see
1024 below).
1025
1026 If an error occurs, the callback receives no arguments. The special
1027 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1028
1029 Otherwise, the callback receives an array reference with extent
1030 structures. Each extent structure is an array reference itself, with
1031 the following members:
1032
1033 [$logical, $physical, $length, $flags]
1034
1035 Flags is any combination of the following flag values (typically
1036 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1037
1038 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1039 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1040 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1041 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1042 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1043 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1044 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1045 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1046
1047 At the time of this writing (Linux 3.2), this requets is unreliable
1048 unless $count is "undef", as the kernel has all sorts of bugs
1049 preventing it to return all extents of a range for files with large
1050 number of extents. The code works around all these issues if $count
1051 is undef.
842 1052
843 aio_group $callback->(...) 1053 aio_group $callback->(...)
844 This is a very special aio request: Instead of doing something, it 1054 This is a very special aio request: Instead of doing something, it
845 is a container for other aio requests, which is useful if you want 1055 is a container for other aio requests, which is useful if you want
846 to bundle many requests into a single, composite, request with a 1056 to bundle many requests into a single, composite, request with a
880 While it is theoretically handy to have simple I/O scheduling 1090 While it is theoretically handy to have simple I/O scheduling
881 requests like sleep and file handle readable/writable, the overhead 1091 requests like sleep and file handle readable/writable, the overhead
882 this creates is immense (it blocks a thread for a long time) so do 1092 this creates is immense (it blocks a thread for a long time) so do
883 not use this function except to put your application under 1093 not use this function except to put your application under
884 artificial I/O pressure. 1094 artificial I/O pressure.
1095
1096 IO::AIO::WD - multiple working directories
1097 Your process only has one current working directory, which is used by
1098 all threads. This makes it hard to use relative paths (some other
1099 component could call "chdir" at any time, and it is hard to control when
1100 the path will be used by IO::AIO).
1101
1102 One solution for this is to always use absolute paths. This usually
1103 works, but can be quite slow (the kernel has to walk the whole path on
1104 every access), and can also be a hassle to implement.
1105
1106 Newer POSIX systems have a number of functions (openat, fdopendir,
1107 futimensat and so on) that make it possible to specify working
1108 directories per operation.
1109
1110 For portability, and because the clowns who "designed", or shall I
1111 write, perpetrated this new interface were obviously half-drunk, this
1112 abstraction cannot be perfect, though.
1113
1114 IO::AIO allows you to convert directory paths into a so-called
1115 IO::AIO::WD object. This object stores the canonicalised, absolute
1116 version of the path, and on systems that allow it, also a directory file
1117 descriptor.
1118
1119 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1120 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1121 object and a pathname instead (or the IO::AIO::WD object alone, which
1122 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1123 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1124 relative to that IO::AIO::WD object.
1125
1126 For example, to get a wd object for /etc and then stat passwd inside,
1127 you would write:
1128
1129 aio_wd "/etc", sub {
1130 my $etcdir = shift;
1131
1132 # although $etcdir can be undef on error, there is generally no reason
1133 # to check for errors here, as aio_stat will fail with ENOENT
1134 # when $etcdir is undef.
1135
1136 aio_stat [$etcdir, "passwd"], sub {
1137 # yay
1138 };
1139 };
1140
1141 The fact that "aio_wd" is a request and not a normal function shows that
1142 creating an IO::AIO::WD object is itself a potentially blocking
1143 operation, which is why it is done asynchronously.
1144
1145 To stat the directory obtained with "aio_wd" above, one could write
1146 either of the following three request calls:
1147
1148 aio_lstat "/etc" , sub { ... # pathname as normal string
1149 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1150 aio_lstat $wd , sub { ... # shorthand for the previous
1151
1152 As with normal pathnames, IO::AIO keeps a copy of the working directory
1153 object and the pathname string, so you could write the following without
1154 causing any issues due to $path getting reused:
1155
1156 my $path = [$wd, undef];
1157
1158 for my $name (qw(abc def ghi)) {
1159 $path->[1] = $name;
1160 aio_stat $path, sub {
1161 # ...
1162 };
1163 }
1164
1165 There are some caveats: when directories get renamed (or deleted), the
1166 pathname string doesn't change, so will point to the new directory (or
1167 nowhere at all), while the directory fd, if available on the system,
1168 will still point to the original directory. Most functions accepting a
1169 pathname will use the directory fd on newer systems, and the string on
1170 older systems. Some functions (such as realpath) will always rely on the
1171 string form of the pathname.
1172
1173 So this functionality is mainly useful to get some protection against
1174 "chdir", to easily get an absolute path out of a relative path for
1175 future reference, and to speed up doing many operations in the same
1176 directory (e.g. when stat'ing all files in a directory).
1177
1178 The following functions implement this working directory abstraction:
1179
1180 aio_wd $pathname, $callback->($wd)
1181 Asynchonously canonicalise the given pathname and convert it to an
1182 IO::AIO::WD object representing it. If possible and supported on the
1183 system, also open a directory fd to speed up pathname resolution
1184 relative to this working directory.
1185
1186 If something goes wrong, then "undef" is passwd to the callback
1187 instead of a working directory object and $! is set appropriately.
1188 Since passing "undef" as working directory component of a pathname
1189 fails the request with "ENOENT", there is often no need for error
1190 checking in the "aio_wd" callback, as future requests using the
1191 value will fail in the expected way.
1192
1193 IO::AIO::CWD
1194 This is a compiletime constant (object) that represents the process
1195 current working directory.
1196
1197 Specifying this object as working directory object for a pathname is
1198 as if the pathname would be specified directly, without a directory
1199 object. For example, these calls are functionally identical:
1200
1201 aio_stat "somefile", sub { ... };
1202 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1203
1204 To recover the path associated with an IO::AIO::WD object, you can use
1205 "aio_realpath":
1206
1207 aio_realpath $wd, sub {
1208 warn "path is $_[0]\n";
1209 };
1210
1211 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1212 sometimes, fall back to using an absolue path.
885 1213
886 IO::AIO::REQ CLASS 1214 IO::AIO::REQ CLASS
887 All non-aggregate "aio_*" functions return an object of this class when 1215 All non-aggregate "aio_*" functions return an object of this class when
888 called in non-void context. 1216 called in non-void context.
889 1217
989 Sets a feeder/generator on this group: every group can have an 1317 Sets a feeder/generator on this group: every group can have an
990 attached generator that generates requests if idle. The idea behind 1318 attached generator that generates requests if idle. The idea behind
991 this is that, although you could just queue as many requests as you 1319 this is that, although you could just queue as many requests as you
992 want in a group, this might starve other requests for a potentially 1320 want in a group, this might starve other requests for a potentially
993 long time. For example, "aio_scandir" might generate hundreds of 1321 long time. For example, "aio_scandir" might generate hundreds of
994 thousands "aio_stat" requests, delaying any later requests for a 1322 thousands of "aio_stat" requests, delaying any later requests for a
995 long time. 1323 long time.
996 1324
997 To avoid this, and allow incremental generation of requests, you can 1325 To avoid this, and allow incremental generation of requests, you can
998 instead a group and set a feeder on it that generates those 1326 instead a group and set a feeder on it that generates those
999 requests. The feed callback will be called whenever there are few 1327 requests. The feed callback will be called whenever there are few
1041 results. 1369 results.
1042 1370
1043 See "poll_cb" for an example. 1371 See "poll_cb" for an example.
1044 1372
1045 IO::AIO::poll_cb 1373 IO::AIO::poll_cb
1046 Process some outstanding events on the result pipe. You have to call 1374 Process some requests that have reached the result phase (i.e. they
1375 have been executed but the results are not yet reported). You have
1376 to call this "regularly" to finish outstanding requests.
1377
1047 this regularly. Returns 0 if all events could be processed (or there 1378 Returns 0 if all events could be processed (or there were no events
1048 were no events to process), or -1 if it returned earlier for 1379 to process), or -1 if it returned earlier for whatever reason.
1049 whatever reason. Returns immediately when no events are outstanding. 1380 Returns immediately when no events are outstanding. The amount of
1050 The amount of events processed depends on the settings of 1381 events processed depends on the settings of "IO::AIO::max_poll_req",
1051 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1382 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1052 1383
1053 If not all requests were processed for whatever reason, the 1384 If not all requests were processed for whatever reason, the poll
1054 filehandle will still be ready when "poll_cb" returns, so normally 1385 file descriptor will still be ready when "poll_cb" returns, so
1055 you don't have to do anything special to have it called later. 1386 normally you don't have to do anything special to have it called
1387 later.
1056 1388
1057 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1389 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1058 becomes ready, it can be beneficial to call this function from loops 1390 becomes ready, it can be beneficial to call this function from loops
1059 which submit a lot of requests, to make sure the results get 1391 which submit a lot of requests, to make sure the results get
1060 processed when they become available and not just when the loop is 1392 processed when they become available and not just when the loop is
1068 Event->io (fd => IO::AIO::poll_fileno, 1400 Event->io (fd => IO::AIO::poll_fileno,
1069 poll => 'r', async => 1, 1401 poll => 'r', async => 1,
1070 cb => \&IO::AIO::poll_cb); 1402 cb => \&IO::AIO::poll_cb);
1071 1403
1072 IO::AIO::poll_wait 1404 IO::AIO::poll_wait
1073 If there are any outstanding requests and none of them in the result 1405 Wait until either at least one request is in the result phase or no
1074 phase, wait till the result filehandle becomes ready for reading 1406 requests are outstanding anymore.
1075 (simply does a "select" on the filehandle. This is useful if you 1407
1076 want to synchronously wait for some requests to finish). 1408 This is useful if you want to synchronously wait for some requests
1409 to become ready, without actually handling them.
1077 1410
1078 See "nreqs" for an example. 1411 See "nreqs" for an example.
1079 1412
1080 IO::AIO::poll 1413 IO::AIO::poll
1081 Waits until some requests have been handled. 1414 Waits until some requests have been handled.
1193 1526
1194 This is a very bad function to use in interactive programs because 1527 This is a very bad function to use in interactive programs because
1195 it blocks, and a bad way to reduce concurrency because it is 1528 it blocks, and a bad way to reduce concurrency because it is
1196 inexact: Better use an "aio_group" together with a feed callback. 1529 inexact: Better use an "aio_group" together with a feed callback.
1197 1530
1198 It's main use is in scripts without an event loop - when you want to 1531 Its main use is in scripts without an event loop - when you want to
1199 stat a lot of files, you can write somehting like this: 1532 stat a lot of files, you can write somehting like this:
1200 1533
1201 IO::AIO::max_outstanding 32; 1534 IO::AIO::max_outstanding 32;
1202 1535
1203 for my $path (...) { 1536 for my $path (...) {
1234 IO::AIO::npending 1567 IO::AIO::npending
1235 Returns the number of requests currently in the pending state 1568 Returns the number of requests currently in the pending state
1236 (executed, but not yet processed by poll_cb). 1569 (executed, but not yet processed by poll_cb).
1237 1570
1238 MISCELLANEOUS FUNCTIONS 1571 MISCELLANEOUS FUNCTIONS
1239 IO::AIO implements some functions that might be useful, but are not 1572 IO::AIO implements some functions that are useful when you want to use
1240 asynchronous. 1573 some "Advanced I/O" function not available to in Perl, without going the
1574 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1575 counterpart.
1241 1576
1242 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1577 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1243 Calls the "eio_sendfile_sync" function, which is like 1578 Calls the "eio_sendfile_sync" function, which is like
1244 "aio_sendfile", but is blocking (this makes most sense if you know 1579 "aio_sendfile", but is blocking (this makes most sense if you know
1245 the input data is likely cached already and the output filehandle is 1580 the input data is likely cached already and the output filehandle is
1247 1582
1248 Returns the number of bytes copied, or -1 on error. 1583 Returns the number of bytes copied, or -1 on error.
1249 1584
1250 IO::AIO::fadvise $fh, $offset, $len, $advice 1585 IO::AIO::fadvise $fh, $offset, $len, $advice
1251 Simply calls the "posix_fadvise" function (see its manpage for 1586 Simply calls the "posix_fadvise" function (see its manpage for
1252 details). The following advice constants are avaiable: 1587 details). The following advice constants are available:
1253 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1588 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1254 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1589 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1255 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1590 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1256 1591
1257 On systems that do not implement "posix_fadvise", this function 1592 On systems that do not implement "posix_fadvise", this function
1258 returns ENOSYS, otherwise the return value of "posix_fadvise". 1593 returns ENOSYS, otherwise the return value of "posix_fadvise".
1259 1594
1260 IO::AIO::madvise $scalar, $offset, $len, $advice 1595 IO::AIO::madvise $scalar, $offset, $len, $advice
1261 Simply calls the "posix_madvise" function (see its manpage for 1596 Simply calls the "posix_madvise" function (see its manpage for
1262 details). The following advice constants are avaiable: 1597 details). The following advice constants are available:
1263 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1598 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1264 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1599 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1265 "IO::AIO::MADV_DONTNEED". 1600 "IO::AIO::MADV_DONTNEED".
1266 1601
1267 On systems that do not implement "posix_madvise", this function 1602 On systems that do not implement "posix_madvise", this function
1268 returns ENOSYS, otherwise the return value of "posix_madvise". 1603 returns ENOSYS, otherwise the return value of "posix_madvise".
1269 1604
1270 IO::AIO::mprotect $scalar, $offset, $len, $protect 1605 IO::AIO::mprotect $scalar, $offset, $len, $protect
1271 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1606 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1272 $scalar (see its manpage for details). The following protect 1607 $scalar (see its manpage for details). The following protect
1273 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1608 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1274 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1609 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1275 1610
1276 On systems that do not implement "mprotect", this function returns 1611 On systems that do not implement "mprotect", this function returns
1277 ENOSYS, otherwise the return value of "mprotect". 1612 ENOSYS, otherwise the return value of "mprotect".
1278 1613
1279 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1614 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1280 Memory-maps a file (or anonymous memory range) and attaches it to 1615 Memory-maps a file (or anonymous memory range) and attaches it to
1281 the given $scalar, which will act like a string scalar. 1616 the given $scalar, which will act like a string scalar. Returns true
1617 on success, and false otherwise.
1282 1618
1283 The only operations allowed on the scalar are "substr"/"vec" that 1619 The only operations allowed on the scalar are "substr"/"vec" that
1284 don't change the string length, and most read-only operations such 1620 don't change the string length, and most read-only operations such
1285 as copying it or searching it with regexes and so on. 1621 as copying it or searching it with regexes and so on.
1286 1622
1300 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1636 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1301 "IO::AIO::PROT_WRITE", 1637 "IO::AIO::PROT_WRITE",
1302 1638
1303 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1639 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1304 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1640 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1305 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1641 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1306 (which is set to "MAP_ANON" if your system only provides this 1642 "MAP_ANON" if your system only provides this constant),
1307 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1643 "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
1308 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1644 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE",
1309 "IO::AIO::MAP_NONBLOCK" 1645 "IO::AIO::MAP_NONBLOCK", "IO::AIO::MAP_FIXED",
1646 "IO::AIO::MAP_GROWSDOWN", "IO::AIO::MAP_32BIT",
1647 "IO::AIO::MAP_HUGETLB" or "IO::AIO::MAP_STACK".
1310 1648
1311 If $fh is "undef", then a file descriptor of -1 is passed. 1649 If $fh is "undef", then a file descriptor of -1 is passed.
1312 1650
1313 $offset is the offset from the start of the file - it generally must 1651 $offset is the offset from the start of the file - it generally must
1314 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1652 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1336 IO::AIO::munlockall 1674 IO::AIO::munlockall
1337 Calls the "munlockall" function. 1675 Calls the "munlockall" function.
1338 1676
1339 On systems that do not implement "munlockall", this function returns 1677 On systems that do not implement "munlockall", this function returns
1340 ENOSYS, otherwise the return value of "munlockall". 1678 ENOSYS, otherwise the return value of "munlockall".
1679
1680 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1681 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1682 $w_off are "undef", then "NULL" is passed for these, otherwise they
1683 should be the file offset.
1684
1685 $r_fh and $w_fh should not refer to the same file, as splice might
1686 silently corrupt the data in this case.
1687
1688 The following symbol flag values are available:
1689 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1690 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1691
1692 See the splice(2) manpage for details.
1693
1694 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1695 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1696 description for "IO::AIO::splice" above for details.
1697
1698 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1699 Attempts to query or change the pipe buffer size. Obviously works
1700 only on pipes, and currently works only on GNU/Linux systems, and
1701 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1702 influence pipe buffer size on other systems, drop me a note.
1703
1704 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1705 This is a direct interface to the Linux pipe2(2) system call. If
1706 $flags is missing or 0, then this should be the same as a call to
1707 perl's built-in "pipe" function and create a new pipe, and works on
1708 systems that lack the pipe2 syscall. On win32, this case invokes
1709 "_pipe (..., 4096, O_BINARY)".
1710
1711 If $flags is non-zero, it tries to invoke the pipe2 system call with
1712 the given flags (Linux 2.6.27, glibc 2.9).
1713
1714 On success, the read and write file handles are returned.
1715
1716 On error, nothing will be returned. If the pipe2 syscall is missing
1717 and $flags is non-zero, fails with "ENOSYS".
1718
1719 Please refer to pipe2(2) for more info on the $flags, but at the
1720 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1721 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1722 supported.
1341 1723
1342EVENT LOOP INTEGRATION 1724EVENT LOOP INTEGRATION
1343 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1725 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1344 automatically into many event loops: 1726 automatically into many event loops:
1345 1727
1371 1753
1372 FORK BEHAVIOUR 1754 FORK BEHAVIOUR
1373 Usage of pthreads in a program changes the semantics of fork 1755 Usage of pthreads in a program changes the semantics of fork
1374 considerably. Specifically, only async-safe functions can be called 1756 considerably. Specifically, only async-safe functions can be called
1375 after fork. Perl doesn't know about this, so in general, you cannot call 1757 after fork. Perl doesn't know about this, so in general, you cannot call
1376 fork with defined behaviour in perl. IO::AIO uses pthreads, so this 1758 fork with defined behaviour in perl if pthreads are involved. IO::AIO
1377 applies, but many other extensions and (for inexplicable reasons) perl 1759 uses pthreads, so this applies, but many other extensions and (for
1378 itself often is linked against pthreads, so this limitation applies. 1760 inexplicable reasons) perl itself often is linked against pthreads, so
1761 this limitation applies to quite a lot of perls.
1379 1762
1380 Some operating systems have extensions that allow safe use of fork, and 1763 This module no longer tries to fight your OS, or POSIX. That means
1381 this module should do "the right thing" on those, and tries on others. 1764 IO::AIO only works in the process that loaded it. Forking is fully
1382 At the time of this writing (2011) only GNU/Linux supports these 1765 supported, but using IO::AIO in the child is not.
1383 extensions to POSIX. 1766
1767 You might get around by not *using* IO::AIO before (or after) forking.
1768 You could also try to call the IO::AIO::reinit function in the child:
1769
1770 IO::AIO::reinit
1771 Abandons all current requests and I/O threads and simply
1772 reinitialises all data structures. This is not an operation
1773 supported by any standards, but happens to work on GNU/Linux and
1774 some newer BSD systems.
1775
1776 The only reasonable use for this function is to call it after
1777 forking, if "IO::AIO" was used in the parent. Calling it while
1778 IO::AIO is active in the process will result in undefined behaviour.
1779 Calling it at any time will also result in any undefined (by POSIX)
1780 behaviour.
1384 1781
1385 MEMORY USAGE 1782 MEMORY USAGE
1386 Per-request usage: 1783 Per-request usage:
1387 1784
1388 Each aio request uses - depending on your architecture - around 100-200 1785 Each aio request uses - depending on your architecture - around 100-200

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