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Revision 1.47 by root, Fri May 27 00:44:49 2011 UTC vs.
Revision 1.54 by root, Sun Jan 6 11:48:14 2013 UTC

146 the actual aio request is severed and calling its methods will 146 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 147 either do nothing or result in a runtime error).
148 148
149FUNCTIONS 149FUNCTIONS
150 QUICK OVERVIEW 150 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 151 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 152 reference. See the following sections for function-by-function
153 documentation. 153 documentation.
154 154
155 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 156 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 157 aio_close $fh, $callback->($status)
158 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 159 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 160 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 161 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 162 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 163 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 164 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 165 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 166 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 167 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
168 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 169 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status) 170 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
171 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168 aio_unlink $pathname, $callback->($status) 172 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 173 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 174 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 175 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 176 aio_readlink $pathname, $callback->($link)
177 aio_realpath $pathname, $callback->($link)
173 aio_rename $srcpath, $dstpath, $callback->($status) 178 aio_rename $srcpath, $dstpath, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status) 179 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status) 180 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries) 181 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 182 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 183 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 184 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
185 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180 aio_load $path, $data, $callback->($status) 186 aio_load $pathname, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status) 187 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status) 188 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status) 189 aio_rmtree $pathname, $callback->($status)
185 aio_sync $callback->($status) 190 aio_sync $callback->($status)
191 aio_syncfs $fh, $callback->($status)
186 aio_fsync $fh, $callback->($status) 192 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status) 193 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 194 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status) 195 aio_pathsync $pathname, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 196 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 197 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 198 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status) 199 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...) 200 aio_group $callback->(...)
212 IO::AIO::nready 218 IO::AIO::nready
213 IO::AIO::npending 219 IO::AIO::npending
214 220
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count 221 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice 222 IO::AIO::fadvise $fh, $offset, $len, $advice
223 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
224 IO::AIO::munmap $scalar
217 IO::AIO::madvise $scalar, $offset, $length, $advice 225 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect 226 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef 227 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall 228 IO::AIO::munlockall
221 229
222 AIO REQUEST FUNCTIONS 230 API NOTES
223 All the "aio_*" calls are more or less thin wrappers around the syscall 231 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 232 with the same name (sans "aio_"). The arguments are similar or
225 identical, and they all accept an additional (and optional) $callback 233 identical, and they all accept an additional (and optional) $callback
226 argument which must be a code reference. This code reference will get 234 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. 235 called after the syscall has been executed in an asynchronous fashion.
236 The results of the request will be passed as arguments to the callback
237 (and, if an error occured, in $!) - for most requests the syscall return
238 code (e.g. most syscalls return -1 on error, unlike perl, which usually
239 delivers "false").
240
241 Some requests (such as "aio_readdir") pass the actual results and
242 communicate failures by passing "undef".
230 243
231 All functions expecting a filehandle keep a copy of the filehandle 244 All functions expecting a filehandle keep a copy of the filehandle
232 internally until the request has finished. 245 internally until the request has finished.
233 246
234 All functions return request objects of type IO::AIO::REQ that allow 247 All functions return request objects of type IO::AIO::REQ that allow
235 further manipulation of those requests while they are in-flight. 248 further manipulation of those requests while they are in-flight.
236 249
237 The pathnames you pass to these routines *must* be absolute and encoded 250 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 251 reason for this is that at the time the request is being executed, the
239 being executed, the current working directory could have changed. 252 current working directory could have changed. Alternatively, you can
240 Alternatively, you can make sure that you never change the current 253 make sure that you never change the current working directory anywhere
241 working directory anywhere in the program and then use relative paths. 254 in the program and then use relative paths. You can also take advantage
255 of IO::AIOs working directory abstraction, that lets you specify paths
256 relative to some previously-opened "working directory object" - see the
257 description of the "IO::AIO::WD" class later in this document.
242 258
243 To encode pathnames as octets, either make sure you either: a) always 259 To encode pathnames as octets, either make sure you either: a) always
244 pass in filenames you got from outside (command line, readdir etc.) 260 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 261 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 262 Encode module and encode your pathnames to the locale (or other)
247 the user environment, d) use Glib::filename_from_unicode on unicode 263 encoding in effect in the user environment, d) use
248 filenames or e) use something else to ensure your scalar has the correct 264 Glib::filename_from_unicode on unicode filenames or e) use something
249 contents. 265 else to ensure your scalar has the correct contents.
250 266
251 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 267 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
252 handles correctly whether it is set or not. 268 handles correctly whether it is set or not.
253 269
270 AIO REQUEST FUNCTIONS
254 $prev_pri = aioreq_pri [$pri] 271 $prev_pri = aioreq_pri [$pri]
255 Returns the priority value that would be used for the next request 272 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. 273 and, if $pri is given, sets the priority for the next aio request.
257 274
258 The default priority is 0, the minimum and maximum priorities are -4 275 The default priority is 0, the minimum and maximum priorities are -4
280 Similar to "aioreq_pri", but subtracts the given value from the 297 Similar to "aioreq_pri", but subtracts the given value from the
281 current priority, so the effect is cumulative. 298 current priority, so the effect is cumulative.
282 299
283 aio_open $pathname, $flags, $mode, $callback->($fh) 300 aio_open $pathname, $flags, $mode, $callback->($fh)
284 Asynchronously open or create a file and call the callback with a 301 Asynchronously open or create a file and call the callback with a
285 newly created filehandle for the file. 302 newly created filehandle for the file (or "undef" in case of an
303 error).
286 304
287 The pathname passed to "aio_open" must be absolute. See API NOTES, 305 The pathname passed to "aio_open" must be absolute. See API NOTES,
288 above, for an explanation. 306 above, for an explanation.
289 307
290 The $flags argument is a bitmask. See the "Fcntl" module for a list. 308 The $flags argument is a bitmask. See the "Fcntl" module for a list.
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.
334 352
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".
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
339 calls the callback without the actual number of bytes read (or -1 on 376 calls the callback without the actual number of bytes read (or -1 on
367 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 404 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
368 Tries to copy $length bytes from $in_fh to $out_fh. It starts 405 Tries to copy $length bytes from $in_fh to $out_fh. It starts
369 reading at byte offset $in_offset, and starts writing at the current 406 reading at byte offset $in_offset, and starts writing at the current
370 file offset of $out_fh. Because of that, it is not safe to issue 407 file offset of $out_fh. Because of that, it is not safe to issue
371 more than one "aio_sendfile" per $out_fh, as they will interfere 408 more than one "aio_sendfile" per $out_fh, as they will interfere
372 with each other. 409 with each other. The same $in_fh works fine though, as this function
410 does not move or use the file offset of $in_fh.
373 411
374 Please note that "aio_sendfile" can read more bytes from $in_fh than 412 Please note that "aio_sendfile" can read more bytes from $in_fh than
375 are written, and there is no way to find out how many bytes have 413 are written, and there is no way to find out how many more bytes
376 been read from "aio_sendfile" alone, as "aio_sendfile" only provides 414 have been read from "aio_sendfile" alone, as "aio_sendfile" only
377 the number of bytes written to $out_fh. Only if the result value 415 provides the number of bytes written to $out_fh. Only if the result
378 equals $length one can assume that $length bytes have been read. 416 value equals $length one can assume that $length bytes have been
417 read.
379 418
380 Unlike with other "aio_" functions, it makes a lot of sense to use 419 Unlike with other "aio_" functions, it makes a lot of sense to use
381 "aio_sendfile" on non-blocking sockets, as long as one end 420 "aio_sendfile" on non-blocking sockets, as long as one end
382 (typically the $in_fh) is a file - the file I/O will then be 421 (typically the $in_fh) is a file - the file I/O will then be
383 asynchronous, while the socket I/O will be non-blocking. Note, 422 asynchronous, while the socket I/O will be non-blocking. Note,
384 however, that you can run into a trap where "aio_sendfile" reads 423 however, that you can run into a trap where "aio_sendfile" reads
385 some data with readahead, then fails to write all data, and when the 424 some data with readahead, then fails to write all data, and when the
386 socket is ready the next time, the data in the cache is already 425 socket is ready the next time, the data in the cache is already
387 lost, forcing "aio_sendfile" to again hit the disk. Explicit 426 lost, forcing "aio_sendfile" to again hit the disk. Explicit
388 "aio_read" + "aio_write" let's you control resource usage much 427 "aio_read" + "aio_write" let's you better control resource usage.
389 better.
390 428
391 This call tries to make use of a native "sendfile" syscall to 429 This call tries to make use of a native "sendfile"-like syscall to
392 provide zero-copy operation. For this to work, $out_fh should refer 430 provide zero-copy operation. For this to work, $out_fh should refer
393 to a socket, and $in_fh should refer to an mmap'able file. 431 to a socket, and $in_fh should refer to an mmap'able file.
394 432
395 If a native sendfile cannot be found or it fails with "ENOSYS", 433 If a native sendfile cannot be found or it fails with "ENOSYS",
396 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", 434 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
397 it will be emulated, so you can call "aio_sendfile" on any type of 435 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
398 filehandle regardless of the limitations of the operating system. 436 any type of filehandle regardless of the limitations of the
437 operating system.
438
439 As native sendfile syscalls (as practically any non-POSIX interface
440 hacked together in a hurry to improve benchmark numbers) tend to be
441 rather buggy on many systems, this implementation tries to work
442 around some known bugs in Linux and FreeBSD kernels (probably
443 others, too), but that might fail, so you really really should check
444 the return value of "aio_sendfile" - fewre bytes than expected might
445 have been transferred.
399 446
400 aio_readahead $fh,$offset,$length, $callback->($retval) 447 aio_readahead $fh,$offset,$length, $callback->($retval)
401 "aio_readahead" populates the page cache with data from a file so 448 "aio_readahead" populates the page cache with data from a file so
402 that subsequent reads from that file will not block on disk I/O. The 449 that subsequent reads from that file will not block on disk I/O. The
403 $offset argument specifies the starting point from which data is to 450 $offset argument specifies the starting point from which data is to
483 namemax => 255, 530 namemax => 255,
484 frsize => 1024, 531 frsize => 1024,
485 fsid => 1810 532 fsid => 1810
486 } 533 }
487 534
535 Here is a (likely partial) list of fsid values used by Linux - it is
536 safe to hardcode these when the $^O is "linux":
537
538 0x0000adf5 adfs
539 0x0000adff affs
540 0x5346414f afs
541 0x09041934 anon-inode filesystem
542 0x00000187 autofs
543 0x42465331 befs
544 0x1badface bfs
545 0x42494e4d binfmt_misc
546 0x9123683e btrfs
547 0x0027e0eb cgroupfs
548 0xff534d42 cifs
549 0x73757245 coda
550 0x012ff7b7 coh
551 0x28cd3d45 cramfs
552 0x453dcd28 cramfs-wend (wrong endianness)
553 0x64626720 debugfs
554 0x00001373 devfs
555 0x00001cd1 devpts
556 0x0000f15f ecryptfs
557 0x00414a53 efs
558 0x0000137d ext
559 0x0000ef53 ext2/ext3
560 0x0000ef51 ext2
561 0x00004006 fat
562 0x65735546 fuseblk
563 0x65735543 fusectl
564 0x0bad1dea futexfs
565 0x01161970 gfs2
566 0x47504653 gpfs
567 0x00004244 hfs
568 0xf995e849 hpfs
569 0x958458f6 hugetlbfs
570 0x2bad1dea inotifyfs
571 0x00009660 isofs
572 0x000072b6 jffs2
573 0x3153464a jfs
574 0x6b414653 k-afs
575 0x0bd00bd0 lustre
576 0x0000137f minix
577 0x0000138f minix 30 char names
578 0x00002468 minix v2
579 0x00002478 minix v2 30 char names
580 0x00004d5a minix v3
581 0x19800202 mqueue
582 0x00004d44 msdos
583 0x0000564c novell
584 0x00006969 nfs
585 0x6e667364 nfsd
586 0x00003434 nilfs
587 0x5346544e ntfs
588 0x00009fa1 openprom
589 0x7461636F ocfs2
590 0x00009fa0 proc
591 0x6165676c pstorefs
592 0x0000002f qnx4
593 0x858458f6 ramfs
594 0x52654973 reiserfs
595 0x00007275 romfs
596 0x67596969 rpc_pipefs
597 0x73636673 securityfs
598 0xf97cff8c selinux
599 0x0000517b smb
600 0x534f434b sockfs
601 0x73717368 squashfs
602 0x62656572 sysfs
603 0x012ff7b6 sysv2
604 0x012ff7b5 sysv4
605 0x01021994 tmpfs
606 0x15013346 udf
607 0x00011954 ufs
608 0x54190100 ufs byteswapped
609 0x00009fa2 usbdevfs
610 0x01021997 v9fs
611 0xa501fcf5 vxfs
612 0xabba1974 xenfs
613 0x012ff7b4 xenix
614 0x58465342 xfs
615 0x012fd16d xia
616
488 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 617 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
489 Works like perl's "utime" function (including the special case of 618 Works like perl's "utime" function (including the special case of
490 $atime and $mtime being undef). Fractional times are supported if 619 $atime and $mtime being undef). Fractional times are supported if
491 the underlying syscalls support them. 620 the underlying syscalls support them.
492 621
514 aio_chown "path", 0, undef; 643 aio_chown "path", 0, undef;
515 644
516 aio_truncate $fh_or_path, $offset, $callback->($status) 645 aio_truncate $fh_or_path, $offset, $callback->($status)
517 Works like truncate(2) or ftruncate(2). 646 Works like truncate(2) or ftruncate(2).
518 647
648 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
649 Allocates or freed disk space according to the $mode argument. See
650 the linux "fallocate" docuemntation for details.
651
652 $mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to
653 allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
654 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
655
656 The file system block size used by "fallocate" is presumably the
657 "f_bsize" returned by "statvfs".
658
659 If "fallocate" isn't available or cannot be emulated (currently no
660 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
661
519 aio_chmod $fh_or_path, $mode, $callback->($status) 662 aio_chmod $fh_or_path, $mode, $callback->($status)
520 Works like perl's "chmod" function. 663 Works like perl's "chmod" function.
521 664
522 aio_unlink $pathname, $callback->($status) 665 aio_unlink $pathname, $callback->($status)
523 Asynchronously unlink (delete) a file and call the callback with the 666 Asynchronously unlink (delete) a file and call the callback with the
524 result code. 667 result code.
525 668
526 aio_mknod $path, $mode, $dev, $callback->($status) 669 aio_mknod $pathname, $mode, $dev, $callback->($status)
527 [EXPERIMENTAL] 670 [EXPERIMENTAL]
528 671
529 Asynchronously create a device node (or fifo). See mknod(2). 672 Asynchronously create a device node (or fifo). See mknod(2).
530 673
531 The only (POSIX-) portable way of calling this function is: 674 The only (POSIX-) portable way of calling this function is:
532 675
533 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 676 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
534 677
535 See "aio_stat" for info about some potentially helpful extra 678 See "aio_stat" for info about some potentially helpful extra
536 constants and functions. 679 constants and functions.
537 680
538 aio_link $srcpath, $dstpath, $callback->($status) 681 aio_link $srcpath, $dstpath, $callback->($status)
542 aio_symlink $srcpath, $dstpath, $callback->($status) 685 aio_symlink $srcpath, $dstpath, $callback->($status)
543 Asynchronously create a new symbolic link to the existing object at 686 Asynchronously create a new symbolic link to the existing object at
544 $srcpath at the path $dstpath and call the callback with the result 687 $srcpath at the path $dstpath and call the callback with the result
545 code. 688 code.
546 689
547 aio_readlink $path, $callback->($link) 690 aio_readlink $pathname, $callback->($link)
548 Asynchronously read the symlink specified by $path and pass it to 691 Asynchronously read the symlink specified by $path and pass it to
549 the callback. If an error occurs, nothing or undef gets passed to 692 the callback. If an error occurs, nothing or undef gets passed to
550 the callback. 693 the callback.
551 694
695 aio_realpath $pathname, $callback->($path)
696 Asynchronously make the path absolute and resolve any symlinks in
697 $path. The resulting path only consists of directories (same as
698 Cwd::realpath).
699
700 This request can be used to get the absolute path of the current
701 working directory by passing it a path of . (a single dot).
702
552 aio_rename $srcpath, $dstpath, $callback->($status) 703 aio_rename $srcpath, $dstpath, $callback->($status)
553 Asynchronously rename the object at $srcpath to $dstpath, just as 704 Asynchronously rename the object at $srcpath to $dstpath, just as
554 rename(2) and call the callback with the result code. 705 rename(2) and call the callback with the result code.
706
707 On systems that support the AIO::WD working directory abstraction
708 natively, the case "[$wd, "."]" as $srcpath is specialcased -
709 instead of failing, "rename" is called on the absolute path of $wd.
555 710
556 aio_mkdir $pathname, $mode, $callback->($status) 711 aio_mkdir $pathname, $mode, $callback->($status)
557 Asynchronously mkdir (create) a directory and call the callback with 712 Asynchronously mkdir (create) a directory and call the callback with
558 the result code. $mode will be modified by the umask at the time the 713 the result code. $mode will be modified by the umask at the time the
559 request is executed, so do not change your umask. 714 request is executed, so do not change your umask.
560 715
561 aio_rmdir $pathname, $callback->($status) 716 aio_rmdir $pathname, $callback->($status)
562 Asynchronously rmdir (delete) a directory and call the callback with 717 Asynchronously rmdir (delete) a directory and call the callback with
563 the result code. 718 the result code.
564 719
720 On systems that support the AIO::WD working directory abstraction
721 natively, the case "[$wd, "."]" is specialcased - instead of
722 failing, "rmdir" is called on the absolute path of $wd.
723
565 aio_readdir $pathname, $callback->($entries) 724 aio_readdir $pathname, $callback->($entries)
566 Unlike the POSIX call of the same name, "aio_readdir" reads an 725 Unlike the POSIX call of the same name, "aio_readdir" reads an
567 entire directory (i.e. opendir + readdir + closedir). The entries 726 entire directory (i.e. opendir + readdir + closedir). The entries
568 will not be sorted, and will NOT include the "." and ".." entries. 727 will not be sorted, and will NOT include the "." and ".." entries.
569 728
570 The callback is passed a single argument which is either "undef" or 729 The callback is passed a single argument which is either "undef" or
571 an array-ref with the filenames. 730 an array-ref with the filenames.
572 731
573 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 732 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
574 Quite similar to "aio_readdir", but the $flags argument allows to 733 Quite similar to "aio_readdir", but the $flags argument allows one
575 tune behaviour and output format. In case of an error, $entries will 734 to tune behaviour and output format. In case of an error, $entries
576 be "undef". 735 will be "undef".
577 736
578 The flags are a combination of the following constants, ORed 737 The flags are a combination of the following constants, ORed
579 together (the flags will also be passed to the callback, possibly 738 together (the flags will also be passed to the callback, possibly
580 modified): 739 modified):
581 740
626 optimal stat order. 785 optimal stat order.
627 786
628 IO::AIO::READDIR_FOUND_UNKNOWN 787 IO::AIO::READDIR_FOUND_UNKNOWN
629 This flag should not be set when calling "aio_readdirx". 788 This flag should not be set when calling "aio_readdirx".
630 Instead, it is being set by "aio_readdirx", when any of the 789 Instead, it is being set by "aio_readdirx", when any of the
631 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 790 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
632 flag therefore indicates that all $type's are known, which can 791 flag therefore indicates that all $type's are known, which can
633 be used to speed up some algorithms. 792 be used to speed up some algorithms.
634 793
635 aio_load $path, $data, $callback->($status) 794 aio_load $pathname, $data, $callback->($status)
636 This is a composite request that tries to fully load the given file 795 This is a composite request that tries to fully load the given file
637 into memory. Status is the same as with aio_read. 796 into memory. Status is the same as with aio_read.
638 797
639 aio_copy $srcpath, $dstpath, $callback->($status) 798 aio_copy $srcpath, $dstpath, $callback->($status)
640 Try to copy the *file* (directories not supported as either source 799 Try to copy the *file* (directories not supported as either source
657 816
658 This is a composite request that tries to rename(2) the file first; 817 This is a composite request that tries to rename(2) the file first;
659 if rename fails with "EXDEV", it copies the file with "aio_copy" 818 if rename fails with "EXDEV", it copies the file with "aio_copy"
660 and, if that is successful, unlinks the $srcpath. 819 and, if that is successful, unlinks the $srcpath.
661 820
662 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 821 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
663 Scans a directory (similar to "aio_readdir") but additionally tries 822 Scans a directory (similar to "aio_readdir") but additionally tries
664 to efficiently separate the entries of directory $path into two sets 823 to efficiently separate the entries of directory $path into two sets
665 of names, directories you can recurse into (directories), and ones 824 of names, directories you can recurse into (directories), and ones
666 you cannot recurse into (everything else, including symlinks to 825 you cannot recurse into (everything else, including symlinks to
667 directories). 826 directories).
700 Then entries will be sorted into likely directories a non-initial 859 Then entries will be sorted into likely directories a non-initial
701 dot currently) and likely non-directories (see "aio_readdirx"). Then 860 dot currently) and likely non-directories (see "aio_readdirx"). Then
702 every entry plus an appended "/." will be "stat"'ed, likely 861 every entry plus an appended "/." will be "stat"'ed, likely
703 directories first, in order of their inode numbers. If that 862 directories first, in order of their inode numbers. If that
704 succeeds, it assumes that the entry is a directory or a symlink to 863 succeeds, it assumes that the entry is a directory or a symlink to
705 directory (which will be checked seperately). This is often faster 864 directory (which will be checked separately). This is often faster
706 than stat'ing the entry itself because filesystems might detect the 865 than stat'ing the entry itself because filesystems might detect the
707 type of the entry without reading the inode data (e.g. ext2fs 866 type of the entry without reading the inode data (e.g. ext2fs
708 filetype feature), even on systems that cannot return the filetype 867 filetype feature), even on systems that cannot return the filetype
709 information on readdir. 868 information on readdir.
710 869
716 875
717 It will also likely work on non-POSIX filesystems with reduced 876 It will also likely work on non-POSIX filesystems with reduced
718 efficiency as those tend to return 0 or 1 as link counts, which 877 efficiency as those tend to return 0 or 1 as link counts, which
719 disables the directory counting heuristic. 878 disables the directory counting heuristic.
720 879
721 aio_rmtree $path, $callback->($status) 880 aio_rmtree $pathname, $callback->($status)
722 Delete a directory tree starting (and including) $path, return the 881 Delete a directory tree starting (and including) $path, return the
723 status of the final "rmdir" only. This is a composite request that 882 status of the final "rmdir" only. This is a composite request that
724 uses "aio_scandir" to recurse into and rmdir directories, and unlink 883 uses "aio_scandir" to recurse into and rmdir directories, and unlink
725 everything else. 884 everything else.
726 885
735 Asynchronously call fdatasync on the given filehandle and call the 894 Asynchronously call fdatasync on the given filehandle and call the
736 callback with the fdatasync result code. 895 callback with the fdatasync result code.
737 896
738 If this call isn't available because your OS lacks it or it couldn't 897 If this call isn't available because your OS lacks it or it couldn't
739 be detected, it will be emulated by calling "fsync" instead. 898 be detected, it will be emulated by calling "fsync" instead.
899
900 aio_syncfs $fh, $callback->($status)
901 Asynchronously call the syncfs syscall to sync the filesystem
902 associated to the given filehandle and call the callback with the
903 syncfs result code. If syncfs is not available, calls sync(), but
904 returns -1 and sets errno to "ENOSYS" nevertheless.
740 905
741 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 906 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
742 Sync the data portion of the file specified by $offset and $length 907 Sync the data portion of the file specified by $offset and $length
743 to disk (but NOT the metadata), by calling the Linux-specific 908 to disk (but NOT the metadata), by calling the Linux-specific
744 sync_file_range call. If sync_file_range is not available or it 909 sync_file_range call. If sync_file_range is not available or it
748 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 913 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
749 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 914 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
750 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 915 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
751 manpage for details. 916 manpage for details.
752 917
753 aio_pathsync $path, $callback->($status) 918 aio_pathsync $pathname, $callback->($status)
754 This request tries to open, fsync and close the given path. This is 919 This request tries to open, fsync and close the given path. This is
755 a composite request intended to sync directories after directory 920 a composite request intended to sync directories after directory
756 operations (E.g. rename). This might not work on all operating 921 operations (E.g. rename). This might not work on all operating
757 systems or have any specific effect, but usually it makes sure that 922 systems or have any specific effect, but usually it makes sure that
758 directory changes get written to disc. It works for anything that 923 directory changes get written to disc. It works for anything that
785 950
786 It touches (reads or writes) all memory pages in the specified range 951 It touches (reads or writes) all memory pages in the specified range
787 inside the scalar. All caveats and parameters are the same as for 952 inside the scalar. All caveats and parameters are the same as for
788 "aio_msync", above, except for flags, which must be either 0 (which 953 "aio_msync", above, except for flags, which must be either 0 (which
789 reads all pages and ensures they are instantiated) or 954 reads all pages and ensures they are instantiated) or
790 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 955 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
791 and writing an octet from it, which dirties the page). 956 and writing an octet from it, which dirties the page).
792 957
793 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 958 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
794 This is a rather advanced IO::AIO call, which works best on 959 This is a rather advanced IO::AIO call, which works best on
795 mmap(2)ed scalars. 960 mmap(2)ed scalars.
827 992
828 Example: asynchronously lock all current and future pages into 993 Example: asynchronously lock all current and future pages into
829 memory. 994 memory.
830 995
831 aio_mlockall IO::AIO::MCL_FUTURE; 996 aio_mlockall IO::AIO::MCL_FUTURE;
997
998 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
999 Queries the extents of the given file (by calling the Linux "FIEMAP"
1000 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1001 details). If the ioctl is not available on your OS, then this
1002 request will fail with "ENOSYS".
1003
1004 $start is the starting offset to query extents for, $length is the
1005 size of the range to query - if it is "undef", then the whole file
1006 will be queried.
1007
1008 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1009 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1010 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1011 query the data portion.
1012
1013 $count is the maximum number of extent records to return. If it is
1014 "undef", then IO::AIO queries all extents of the range. As a very
1015 special case, if it is 0, then the callback receives the number of
1016 extents instead of the extents themselves (which is unreliable, see
1017 below).
1018
1019 If an error occurs, the callback receives no arguments. The special
1020 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1021
1022 Otherwise, the callback receives an array reference with extent
1023 structures. Each extent structure is an array reference itself, with
1024 the following members:
1025
1026 [$logical, $physical, $length, $flags]
1027
1028 Flags is any combination of the following flag values (typically
1029 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1030
1031 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1032 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1033 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1034 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1035 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1036 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1037 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1038 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1039
1040 At the time of this writing (Linux 3.2), this requets is unreliable
1041 unless $count is "undef", as the kernel has all sorts of bugs
1042 preventing it to return all extents of a range for files with large
1043 number of extents. The code works around all these issues if $count
1044 is undef.
832 1045
833 aio_group $callback->(...) 1046 aio_group $callback->(...)
834 This is a very special aio request: Instead of doing something, it 1047 This is a very special aio request: Instead of doing something, it
835 is a container for other aio requests, which is useful if you want 1048 is a container for other aio requests, which is useful if you want
836 to bundle many requests into a single, composite, request with a 1049 to bundle many requests into a single, composite, request with a
870 While it is theoretically handy to have simple I/O scheduling 1083 While it is theoretically handy to have simple I/O scheduling
871 requests like sleep and file handle readable/writable, the overhead 1084 requests like sleep and file handle readable/writable, the overhead
872 this creates is immense (it blocks a thread for a long time) so do 1085 this creates is immense (it blocks a thread for a long time) so do
873 not use this function except to put your application under 1086 not use this function except to put your application under
874 artificial I/O pressure. 1087 artificial I/O pressure.
1088
1089 IO::AIO::WD - multiple working directories
1090 Your process only has one current working directory, which is used by
1091 all threads. This makes it hard to use relative paths (some other
1092 component could call "chdir" at any time, and it is hard to control when
1093 the path will be used by IO::AIO).
1094
1095 One solution for this is to always use absolute paths. This usually
1096 works, but can be quite slow (the kernel has to walk the whole path on
1097 every access), and can also be a hassle to implement.
1098
1099 Newer POSIX systems have a number of functions (openat, fdopendir,
1100 futimensat and so on) that make it possible to specify working
1101 directories per operation.
1102
1103 For portability, and because the clowns who "designed", or shall I
1104 write, perpetrated this new interface were obviously half-drunk, this
1105 abstraction cannot be perfect, though.
1106
1107 IO::AIO allows you to convert directory paths into a so-called
1108 IO::AIO::WD object. This object stores the canonicalised, absolute
1109 version of the path, and on systems that allow it, also a directory file
1110 descriptor.
1111
1112 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1113 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1114 object and a pathname instead (or the IO::AIO::WD object alone, which
1115 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1116 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1117 relative to that IO::AIO::WD object.
1118
1119 For example, to get a wd object for /etc and then stat passwd inside,
1120 you would write:
1121
1122 aio_wd "/etc", sub {
1123 my $etcdir = shift;
1124
1125 # although $etcdir can be undef on error, there is generally no reason
1126 # to check for errors here, as aio_stat will fail with ENOENT
1127 # when $etcdir is undef.
1128
1129 aio_stat [$etcdir, "passwd"], sub {
1130 # yay
1131 };
1132 };
1133
1134 That "aio_wd" is a request and not a normal function shows that creating
1135 an IO::AIO::WD object is itself a potentially blocking operation, which
1136 is why it is done asynchronously.
1137
1138 To stat the directory obtained with "aio_wd" above, one could write
1139 either of the following three request calls:
1140
1141 aio_lstat "/etc" , sub { ... # pathname as normal string
1142 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1143 aio_lstat $wd , sub { ... # shorthand for the previous
1144
1145 As with normal pathnames, IO::AIO keeps a copy of the working directory
1146 object and the pathname string, so you could write the following without
1147 causing any issues due to $path getting reused:
1148
1149 my $path = [$wd, undef];
1150
1151 for my $name (qw(abc def ghi)) {
1152 $path->[1] = $name;
1153 aio_stat $path, sub {
1154 # ...
1155 };
1156 }
1157
1158 There are some caveats: when directories get renamed (or deleted), the
1159 pathname string doesn't change, so will point to the new directory (or
1160 nowhere at all), while the directory fd, if available on the system,
1161 will still point to the original directory. Most functions accepting a
1162 pathname will use the directory fd on newer systems, and the string on
1163 older systems. Some functions (such as realpath) will always rely on the
1164 string form of the pathname.
1165
1166 So this functionality is mainly useful to get some protection against
1167 "chdir", to easily get an absolute path out of a relative path for
1168 future reference, and to speed up doing many operations in the same
1169 directory (e.g. when stat'ing all files in a directory).
1170
1171 The following functions implement this working directory abstraction:
1172
1173 aio_wd $pathname, $callback->($wd)
1174 Asynchonously canonicalise the given pathname and convert it to an
1175 IO::AIO::WD object representing it. If possible and supported on the
1176 system, also open a directory fd to speed up pathname resolution
1177 relative to this working directory.
1178
1179 If something goes wrong, then "undef" is passwd to the callback
1180 instead of a working directory object and $! is set appropriately.
1181 Since passing "undef" as working directory component of a pathname
1182 fails the request with "ENOENT", there is often no need for error
1183 checking in the "aio_wd" callback, as future requests using the
1184 value will fail in the expected way.
1185
1186 If this call isn't available because your OS lacks it or it couldn't
1187 be detected, it will be emulated by calling "fsync" instead.
1188
1189 IO::AIO::CWD
1190 This is a compiletime constant (object) that represents the process
1191 current working directory.
1192
1193 Specifying this object as working directory object for a pathname is
1194 as if the pathname would be specified directly, without a directory
1195 object. For example, these calls are functionally identical:
1196
1197 aio_stat "somefile", sub { ... };
1198 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1199
1200 To recover the path associated with an IO::AIO::WD object, you can use
1201 "aio_realpath":
1202
1203 aio_realpath $wd, sub {
1204 warn "path is $_[0]\n";
1205 };
1206
1207 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1208 sometimes, fall back to using an absolue path.
875 1209
876 IO::AIO::REQ CLASS 1210 IO::AIO::REQ CLASS
877 All non-aggregate "aio_*" functions return an object of this class when 1211 All non-aggregate "aio_*" functions return an object of this class when
878 called in non-void context. 1212 called in non-void context.
879 1213
979 Sets a feeder/generator on this group: every group can have an 1313 Sets a feeder/generator on this group: every group can have an
980 attached generator that generates requests if idle. The idea behind 1314 attached generator that generates requests if idle. The idea behind
981 this is that, although you could just queue as many requests as you 1315 this is that, although you could just queue as many requests as you
982 want in a group, this might starve other requests for a potentially 1316 want in a group, this might starve other requests for a potentially
983 long time. For example, "aio_scandir" might generate hundreds of 1317 long time. For example, "aio_scandir" might generate hundreds of
984 thousands "aio_stat" requests, delaying any later requests for a 1318 thousands of "aio_stat" requests, delaying any later requests for a
985 long time. 1319 long time.
986 1320
987 To avoid this, and allow incremental generation of requests, you can 1321 To avoid this, and allow incremental generation of requests, you can
988 instead a group and set a feeder on it that generates those 1322 instead a group and set a feeder on it that generates those
989 requests. The feed callback will be called whenever there are few 1323 requests. The feed callback will be called whenever there are few
1031 results. 1365 results.
1032 1366
1033 See "poll_cb" for an example. 1367 See "poll_cb" for an example.
1034 1368
1035 IO::AIO::poll_cb 1369 IO::AIO::poll_cb
1036 Process some outstanding events on the result pipe. You have to call 1370 Process some requests that have reached the result phase (i.e. they
1371 have been executed but the results are not yet reported). You have
1372 to call this "regularly" to finish outstanding requests.
1373
1037 this regularly. Returns 0 if all events could be processed (or there 1374 Returns 0 if all events could be processed (or there were no events
1038 were no events to process), or -1 if it returned earlier for 1375 to process), or -1 if it returned earlier for whatever reason.
1039 whatever reason. Returns immediately when no events are outstanding. 1376 Returns immediately when no events are outstanding. The amount of
1040 The amount of events processed depends on the settings of 1377 events processed depends on the settings of "IO::AIO::max_poll_req",
1041 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1378 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1042 1379
1043 If not all requests were processed for whatever reason, the 1380 If not all requests were processed for whatever reason, the poll
1044 filehandle will still be ready when "poll_cb" returns, so normally 1381 file descriptor will still be ready when "poll_cb" returns, so
1045 you don't have to do anything special to have it called later. 1382 normally you don't have to do anything special to have it called
1383 later.
1046 1384
1047 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1385 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1048 becomes ready, it can be beneficial to call this function from loops 1386 becomes ready, it can be beneficial to call this function from loops
1049 which submit a lot of requests, to make sure the results get 1387 which submit a lot of requests, to make sure the results get
1050 processed when they become available and not just when the loop is 1388 processed when they become available and not just when the loop is
1058 Event->io (fd => IO::AIO::poll_fileno, 1396 Event->io (fd => IO::AIO::poll_fileno,
1059 poll => 'r', async => 1, 1397 poll => 'r', async => 1,
1060 cb => \&IO::AIO::poll_cb); 1398 cb => \&IO::AIO::poll_cb);
1061 1399
1062 IO::AIO::poll_wait 1400 IO::AIO::poll_wait
1063 If there are any outstanding requests and none of them in the result 1401 Wait until either at least one request is in the result phase or no
1064 phase, wait till the result filehandle becomes ready for reading 1402 requests are outstanding anymore.
1065 (simply does a "select" on the filehandle. This is useful if you 1403
1066 want to synchronously wait for some requests to finish). 1404 This is useful if you want to synchronously wait for some requests
1405 to become ready, without actually handling them.
1067 1406
1068 See "nreqs" for an example. 1407 See "nreqs" for an example.
1069 1408
1070 IO::AIO::poll 1409 IO::AIO::poll
1071 Waits until some requests have been handled. 1410 Waits until some requests have been handled.
1170 IO::AIO::idle_timeout $seconds 1509 IO::AIO::idle_timeout $seconds
1171 Sets the minimum idle timeout (default 10) after which worker 1510 Sets the minimum idle timeout (default 10) after which worker
1172 threads are allowed to exit. SEe "IO::AIO::max_idle". 1511 threads are allowed to exit. SEe "IO::AIO::max_idle".
1173 1512
1174 IO::AIO::max_outstanding $maxreqs 1513 IO::AIO::max_outstanding $maxreqs
1514 Sets the maximum number of outstanding requests to $nreqs. If you do
1515 queue up more than this number of requests, the next call to
1516 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
1517 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1518 no longer exceeded.
1519
1520 In other words, this setting does not enforce a queue limit, but can
1521 be used to make poll functions block if the limit is exceeded.
1522
1175 This is a very bad function to use in interactive programs because 1523 This is a very bad function to use in interactive programs because
1176 it blocks, and a bad way to reduce concurrency because it is 1524 it blocks, and a bad way to reduce concurrency because it is
1177 inexact: Better use an "aio_group" together with a feed callback. 1525 inexact: Better use an "aio_group" together with a feed callback.
1178 1526
1179 Sets the maximum number of outstanding requests to $nreqs. If you do 1527 It's main use is in scripts without an event loop - when you want to
1180 queue up more than this number of requests, the next call to the 1528 stat a lot of files, you can write somehting like this:
1181 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
1182 function will block until the limit is no longer exceeded.
1183 1529
1184 The default value is very large, so there is no practical limit on 1530 IO::AIO::max_outstanding 32;
1531
1532 for my $path (...) {
1533 aio_stat $path , ...;
1534 IO::AIO::poll_cb;
1535 }
1536
1537 IO::AIO::flush;
1538
1539 The call to "poll_cb" inside the loop will normally return
1540 instantly, but as soon as more thna 32 reqeusts are in-flight, it
1541 will block until some requests have been handled. This keeps the
1542 loop from pushing a large number of "aio_stat" requests onto the
1543 queue.
1544
1545 The default value for "max_outstanding" is very large, so there is
1185 the number of outstanding requests. 1546 no practical limit on the number of outstanding requests.
1186
1187 You can still queue as many requests as you want. Therefore,
1188 "max_outstanding" is mainly useful in simple scripts (with low
1189 values) or as a stop gap to shield against fatal memory overflow
1190 (with large values).
1191 1547
1192 STATISTICAL INFORMATION 1548 STATISTICAL INFORMATION
1193 IO::AIO::nreqs 1549 IO::AIO::nreqs
1194 Returns the number of requests currently in the ready, execute or 1550 Returns the number of requests currently in the ready, execute or
1195 pending states (i.e. for which their callback has not been invoked 1551 pending states (i.e. for which their callback has not been invoked
1220 1576
1221 Returns the number of bytes copied, or -1 on error. 1577 Returns the number of bytes copied, or -1 on error.
1222 1578
1223 IO::AIO::fadvise $fh, $offset, $len, $advice 1579 IO::AIO::fadvise $fh, $offset, $len, $advice
1224 Simply calls the "posix_fadvise" function (see its manpage for 1580 Simply calls the "posix_fadvise" function (see its manpage for
1225 details). The following advice constants are avaiable: 1581 details). The following advice constants are available:
1226 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1582 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1227 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1583 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1228 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1584 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1229 1585
1230 On systems that do not implement "posix_fadvise", this function 1586 On systems that do not implement "posix_fadvise", this function
1231 returns ENOSYS, otherwise the return value of "posix_fadvise". 1587 returns ENOSYS, otherwise the return value of "posix_fadvise".
1232 1588
1233 IO::AIO::madvise $scalar, $offset, $len, $advice 1589 IO::AIO::madvise $scalar, $offset, $len, $advice
1234 Simply calls the "posix_madvise" function (see its manpage for 1590 Simply calls the "posix_madvise" function (see its manpage for
1235 details). The following advice constants are avaiable: 1591 details). The following advice constants are available:
1236 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1592 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1237 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1593 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1238 "IO::AIO::MADV_DONTNEED". 1594 "IO::AIO::MADV_DONTNEED".
1239 1595
1240 On systems that do not implement "posix_madvise", this function 1596 On systems that do not implement "posix_madvise", this function
1241 returns ENOSYS, otherwise the return value of "posix_madvise". 1597 returns ENOSYS, otherwise the return value of "posix_madvise".
1242 1598
1243 IO::AIO::mprotect $scalar, $offset, $len, $protect 1599 IO::AIO::mprotect $scalar, $offset, $len, $protect
1244 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1600 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1245 $scalar (see its manpage for details). The following protect 1601 $scalar (see its manpage for details). The following protect
1246 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1602 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1247 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1603 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1248 1604
1249 On systems that do not implement "mprotect", this function returns 1605 On systems that do not implement "mprotect", this function returns
1250 ENOSYS, otherwise the return value of "mprotect". 1606 ENOSYS, otherwise the return value of "mprotect".
1251 1607
1252 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1608 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1253 Memory-maps a file (or anonymous memory range) and attaches it to 1609 Memory-maps a file (or anonymous memory range) and attaches it to
1254 the given $scalar, which will act like a string scalar. 1610 the given $scalar, which will act like a string scalar. Returns true
1611 on success, and false otherwise.
1255 1612
1256 The only operations allowed on the scalar are "substr"/"vec" that 1613 The only operations allowed on the scalar are "substr"/"vec" that
1257 don't change the string length, and most read-only operations such 1614 don't change the string length, and most read-only operations such
1258 as copying it or searching it with regexes and so on. 1615 as copying it or searching it with regexes and so on.
1259 1616
1310 Calls the "munlockall" function. 1667 Calls the "munlockall" function.
1311 1668
1312 On systems that do not implement "munlockall", this function returns 1669 On systems that do not implement "munlockall", this function returns
1313 ENOSYS, otherwise the return value of "munlockall". 1670 ENOSYS, otherwise the return value of "munlockall".
1314 1671
1672 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1673 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1674 $w_off are "undef", then "NULL" is passed for these, otherwise they
1675 should be the file offset.
1676
1677 $r_fh and $w_fh should not refer to the same file, as splice might
1678 silently corrupt the data in this case.
1679
1680 The following symbol flag values are available:
1681 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1682 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1683
1684 See the splice(2) manpage for details.
1685
1686 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1687 Calls the GNU/Linux tee(2) syscall, see it's manpage and the
1688 description for "IO::AIO::splice" above for details.
1689
1315EVENT LOOP INTEGRATION 1690EVENT LOOP INTEGRATION
1316 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1691 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1317 automatically into many event loops: 1692 automatically into many event loops:
1318 1693
1319 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) 1694 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1341 # Danga::Socket integration 1716 # Danga::Socket integration
1342 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 1717 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1343 \&IO::AIO::poll_cb); 1718 \&IO::AIO::poll_cb);
1344 1719
1345 FORK BEHAVIOUR 1720 FORK BEHAVIOUR
1346 This module should do "the right thing" when the process using it forks: 1721 Usage of pthreads in a program changes the semantics of fork
1722 considerably. Specifically, only async-safe functions can be called
1723 after fork. Perl doesn't know about this, so in general, you cannot call
1724 fork with defined behaviour in perl if pthreads are involved. IO::AIO
1725 uses pthreads, so this applies, but many other extensions and (for
1726 inexplicable reasons) perl itself often is linked against pthreads, so
1727 this limitation applies to quite a lot of perls.
1347 1728
1348 Before the fork, IO::AIO enters a quiescent state where no requests can 1729 This module no longer tries to fight your OS, or POSIX. That means
1349 be added in other threads and no results will be processed. After the 1730 IO::AIO only works in the process that loaded it. Forking is fully
1350 fork the parent simply leaves the quiescent state and continues 1731 supported, but using IO::AIO in the child is not.
1351 request/result processing, while the child frees the request/result
1352 queue (so that the requests started before the fork will only be handled
1353 in the parent). Threads will be started on demand until the limit set in
1354 the parent process has been reached again.
1355 1732
1356 In short: the parent will, after a short pause, continue as if fork had 1733 You might get around by not *using* IO::AIO before (or after) forking.
1357 not been called, while the child will act as if IO::AIO has not been 1734 You could also try to call the IO::AIO::reinit function in the child:
1358 used yet. 1735
1736 IO::AIO::reinit
1737 Abandons all current requests and I/O threads and simply
1738 reinitialises all data structures. This is not an operation
1739 supported by any standards, but happens to work on GNU/Linux and
1740 some newer BSD systems.
1741
1742 The only reasonable use for this function is to call it after
1743 forking, if "IO::AIO" was used in the parent. Calling it while
1744 IO::AIO is active in the process will result in undefined behaviour.
1745 Calling it at any time will also result in any undefined (by POSIX)
1746 behaviour.
1359 1747
1360 MEMORY USAGE 1748 MEMORY USAGE
1361 Per-request usage: 1749 Per-request usage:
1362 1750
1363 Each aio request uses - depending on your architecture - around 100-200 1751 Each aio request uses - depending on your architecture - around 100-200

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