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Revision 1.44 by root, Mon Nov 1 22:03:43 2010 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->(...)
204 IO::AIO::max_poll_reqs $nreqs 210 IO::AIO::max_poll_reqs $nreqs
205 IO::AIO::max_poll_time $seconds 211 IO::AIO::max_poll_time $seconds
206 IO::AIO::min_parallel $nthreads 212 IO::AIO::min_parallel $nthreads
207 IO::AIO::max_parallel $nthreads 213 IO::AIO::max_parallel $nthreads
208 IO::AIO::max_idle $nthreads 214 IO::AIO::max_idle $nthreads
215 IO::AIO::idle_timeout $seconds
209 IO::AIO::max_outstanding $maxreqs 216 IO::AIO::max_outstanding $maxreqs
210 IO::AIO::nreqs 217 IO::AIO::nreqs
211 IO::AIO::nready 218 IO::AIO::nready
212 IO::AIO::npending 219 IO::AIO::npending
213 220
214 IO::AIO::sendfile $ofh, $ifh, $offset, $count 221 IO::AIO::sendfile $ofh, $ifh, $offset, $count
215 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
216 IO::AIO::madvise $scalar, $offset, $length, $advice 225 IO::AIO::madvise $scalar, $offset, $length, $advice
217 IO::AIO::mprotect $scalar, $offset, $length, $protect 226 IO::AIO::mprotect $scalar, $offset, $length, $protect
218 IO::AIO::munlock $scalar, $offset = 0, $length = undef 227 IO::AIO::munlock $scalar, $offset = 0, $length = undef
219 IO::AIO::munlockall 228 IO::AIO::munlockall
220 229
221 AIO REQUEST FUNCTIONS 230 API NOTES
222 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
223 with the same name (sans "aio_"). The arguments are similar or 232 with the same name (sans "aio_"). The arguments are similar or
224 identical, and they all accept an additional (and optional) $callback 233 identical, and they all accept an additional (and optional) $callback
225 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
226 called with the syscall return code (e.g. most syscalls return -1 on
227 error, unlike perl, which usually delivers "false") as its sole argument
228 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".
229 243
230 All functions expecting a filehandle keep a copy of the filehandle 244 All functions expecting a filehandle keep a copy of the filehandle
231 internally until the request has finished. 245 internally until the request has finished.
232 246
233 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
234 further manipulation of those requests while they are in-flight. 248 further manipulation of those requests while they are in-flight.
235 249
236 The pathnames you pass to these routines *must* be absolute and encoded 250 The pathnames you pass to these routines *should* be absolute. The
237 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
238 being executed, the current working directory could have changed. 252 current working directory could have changed. Alternatively, you can
239 Alternatively, you can make sure that you never change the current 253 make sure that you never change the current working directory anywhere
240 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.
241 258
242 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
243 pass in filenames you got from outside (command line, readdir etc.) 260 pass in filenames you got from outside (command line, readdir etc.)
244 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
245 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)
246 the user environment, d) use Glib::filename_from_unicode on unicode 263 encoding in effect in the user environment, d) use
247 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
248 contents. 265 else to ensure your scalar has the correct contents.
249 266
250 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
251 handles correctly whether it is set or not. 268 handles correctly whether it is set or not.
252 269
270 AIO REQUEST FUNCTIONS
253 $prev_pri = aioreq_pri [$pri] 271 $prev_pri = aioreq_pri [$pri]
254 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
255 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.
256 274
257 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
279 Similar to "aioreq_pri", but subtracts the given value from the 297 Similar to "aioreq_pri", but subtracts the given value from the
280 current priority, so the effect is cumulative. 298 current priority, so the effect is cumulative.
281 299
282 aio_open $pathname, $flags, $mode, $callback->($fh) 300 aio_open $pathname, $flags, $mode, $callback->($fh)
283 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
284 newly created filehandle for the file. 302 newly created filehandle for the file (or "undef" in case of an
303 error).
285 304
286 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,
287 above, for an explanation. 306 above, for an explanation.
288 307
289 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.
305 } else { 324 } else {
306 die "open failed: $!\n"; 325 die "open failed: $!\n";
307 } 326 }
308 }; 327 };
309 328
329 In addition to all the common open modes/flags ("O_RDONLY",
330 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
331 "O_APPEND"), the following POSIX and non-POSIX constants are
332 available (missing ones on your system are, as usual, 0):
333
334 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
335 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
336 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
337
310 aio_close $fh, $callback->($status) 338 aio_close $fh, $callback->($status)
311 Asynchronously close a file and call the callback with the result 339 Asynchronously close a file and call the callback with the result
312 code. 340 code.
313 341
314 Unfortunately, you can't do this to perl. Perl *insists* very 342 Unfortunately, you can't do this to perl. Perl *insists* very
319 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
320 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).
321 349
322 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
323 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".
324 371
325 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 372 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
326 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 373 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
327 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
328 $offset into the scalar given by $data and offset $dataoffset and 375 $offset into the scalar given by $data and offset $dataoffset and
357 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 404 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
358 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
359 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
360 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
361 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
362 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.
363 411
412 Please note that "aio_sendfile" can read more bytes from $in_fh than
413 are written, and there is no way to find out how many more bytes
414 have been read from "aio_sendfile" alone, as "aio_sendfile" only
415 provides the number of bytes written to $out_fh. Only if the result
416 value equals $length one can assume that $length bytes have been
417 read.
418
419 Unlike with other "aio_" functions, it makes a lot of sense to use
420 "aio_sendfile" on non-blocking sockets, as long as one end
421 (typically the $in_fh) is a file - the file I/O will then be
422 asynchronous, while the socket I/O will be non-blocking. Note,
423 however, that you can run into a trap where "aio_sendfile" reads
424 some data with readahead, then fails to write all data, and when the
425 socket is ready the next time, the data in the cache is already
426 lost, forcing "aio_sendfile" to again hit the disk. Explicit
427 "aio_read" + "aio_write" let's you better control resource usage.
428
364 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
365 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
366 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.
367 432
368 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",
369 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", 434 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
370 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
371 filehandle regardless of the limitations of the operating system. 436 any type of filehandle regardless of the limitations of the
437 operating system.
372 438
373 Please note, however, that "aio_sendfile" can read more bytes from 439 As native sendfile syscalls (as practically any non-POSIX interface
374 $in_fh than are written, and there is no way to find out how many 440 hacked together in a hurry to improve benchmark numbers) tend to be
375 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 441 rather buggy on many systems, this implementation tries to work
376 only provides the number of bytes written to $out_fh. Only if the 442 around some known bugs in Linux and FreeBSD kernels (probably
377 result value equals $length one can assume that $length bytes have 443 others, too), but that might fail, so you really really should check
378 been read. 444 the return value of "aio_sendfile" - fewre bytes than expected might
445 have been transferred.
379 446
380 aio_readahead $fh,$offset,$length, $callback->($retval) 447 aio_readahead $fh,$offset,$length, $callback->($retval)
381 "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
382 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
383 $offset argument specifies the starting point from which data is to 450 $offset argument specifies the starting point from which data is to
403 470
404 Currently, the stats are always 64-bit-stats, i.e. instead of 471 Currently, the stats are always 64-bit-stats, i.e. instead of
405 returning an error when stat'ing a large file, the results will be 472 returning an error when stat'ing a large file, the results will be
406 silently truncated unless perl itself is compiled with large file 473 silently truncated unless perl itself is compiled with large file
407 support. 474 support.
475
476 To help interpret the mode and dev/rdev stat values, IO::AIO offers
477 the following constants and functions (if not implemented, the
478 constants will be 0 and the functions will either "croak" or fall
479 back on traditional behaviour).
480
481 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
482 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
483 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
408 484
409 Example: Print the length of /etc/passwd: 485 Example: Print the length of /etc/passwd:
410 486
411 aio_stat "/etc/passwd", sub { 487 aio_stat "/etc/passwd", sub {
412 $_[0] and die "stat failed: $!"; 488 $_[0] and die "stat failed: $!";
454 namemax => 255, 530 namemax => 255,
455 frsize => 1024, 531 frsize => 1024,
456 fsid => 1810 532 fsid => 1810
457 } 533 }
458 534
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
459 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 617 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
460 Works like perl's "utime" function (including the special case of 618 Works like perl's "utime" function (including the special case of
461 $atime and $mtime being undef). Fractional times are supported if 619 $atime and $mtime being undef). Fractional times are supported if
462 the underlying syscalls support them. 620 the underlying syscalls support them.
463 621
485 aio_chown "path", 0, undef; 643 aio_chown "path", 0, undef;
486 644
487 aio_truncate $fh_or_path, $offset, $callback->($status) 645 aio_truncate $fh_or_path, $offset, $callback->($status)
488 Works like truncate(2) or ftruncate(2). 646 Works like truncate(2) or ftruncate(2).
489 647
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
490 aio_chmod $fh_or_path, $mode, $callback->($status) 662 aio_chmod $fh_or_path, $mode, $callback->($status)
491 Works like perl's "chmod" function. 663 Works like perl's "chmod" function.
492 664
493 aio_unlink $pathname, $callback->($status) 665 aio_unlink $pathname, $callback->($status)
494 Asynchronously unlink (delete) a file and call the callback with the 666 Asynchronously unlink (delete) a file and call the callback with the
495 result code. 667 result code.
496 668
497 aio_mknod $path, $mode, $dev, $callback->($status) 669 aio_mknod $pathname, $mode, $dev, $callback->($status)
498 [EXPERIMENTAL] 670 [EXPERIMENTAL]
499 671
500 Asynchronously create a device node (or fifo). See mknod(2). 672 Asynchronously create a device node (or fifo). See mknod(2).
501 673
502 The only (POSIX-) portable way of calling this function is: 674 The only (POSIX-) portable way of calling this function is:
503 675
504 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 676 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
677
678 See "aio_stat" for info about some potentially helpful extra
679 constants and functions.
505 680
506 aio_link $srcpath, $dstpath, $callback->($status) 681 aio_link $srcpath, $dstpath, $callback->($status)
507 Asynchronously create a new link to the existing object at $srcpath 682 Asynchronously create a new link to the existing object at $srcpath
508 at the path $dstpath and call the callback with the result code. 683 at the path $dstpath and call the callback with the result code.
509 684
510 aio_symlink $srcpath, $dstpath, $callback->($status) 685 aio_symlink $srcpath, $dstpath, $callback->($status)
511 Asynchronously create a new symbolic link to the existing object at 686 Asynchronously create a new symbolic link to the existing object at
512 $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
513 code. 688 code.
514 689
515 aio_readlink $path, $callback->($link) 690 aio_readlink $pathname, $callback->($link)
516 Asynchronously read the symlink specified by $path and pass it to 691 Asynchronously read the symlink specified by $path and pass it to
517 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
518 the callback. 693 the callback.
519 694
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
520 aio_rename $srcpath, $dstpath, $callback->($status) 703 aio_rename $srcpath, $dstpath, $callback->($status)
521 Asynchronously rename the object at $srcpath to $dstpath, just as 704 Asynchronously rename the object at $srcpath to $dstpath, just as
522 rename(2) and call the callback with the result code. 705 rename(2) and call the callback with the result code.
706
707 On systems that support the AIO::WD working directory abstraction
708 natively, the case "[$wd, "."]" as $srcpath is specialcased -
709 instead of failing, "rename" is called on the absolute path of $wd.
523 710
524 aio_mkdir $pathname, $mode, $callback->($status) 711 aio_mkdir $pathname, $mode, $callback->($status)
525 Asynchronously mkdir (create) a directory and call the callback with 712 Asynchronously mkdir (create) a directory and call the callback with
526 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
527 request is executed, so do not change your umask. 714 request is executed, so do not change your umask.
528 715
529 aio_rmdir $pathname, $callback->($status) 716 aio_rmdir $pathname, $callback->($status)
530 Asynchronously rmdir (delete) a directory and call the callback with 717 Asynchronously rmdir (delete) a directory and call the callback with
531 the result code. 718 the result code.
532 719
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
533 aio_readdir $pathname, $callback->($entries) 724 aio_readdir $pathname, $callback->($entries)
534 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
535 entire directory (i.e. opendir + readdir + closedir). The entries 726 entire directory (i.e. opendir + readdir + closedir). The entries
536 will not be sorted, and will NOT include the "." and ".." entries. 727 will not be sorted, and will NOT include the "." and ".." entries.
537 728
538 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
539 an array-ref with the filenames. 730 an array-ref with the filenames.
540 731
541 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 732 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
542 Quite similar to "aio_readdir", but the $flags argument allows to 733 Quite similar to "aio_readdir", but the $flags argument allows one
543 tune behaviour and output format. In case of an error, $entries will 734 to tune behaviour and output format. In case of an error, $entries
544 be "undef". 735 will be "undef".
545 736
546 The flags are a combination of the following constants, ORed 737 The flags are a combination of the following constants, ORed
547 together (the flags will also be passed to the callback, possibly 738 together (the flags will also be passed to the callback, possibly
548 modified): 739 modified):
549 740
550 IO::AIO::READDIR_DENTS 741 IO::AIO::READDIR_DENTS
551 When this flag is off, then the callback gets an arrayref with 742 When this flag is off, then the callback gets an arrayref
552 of names only (as with "aio_readdir"), otherwise it gets an 743 consisting of names only (as with "aio_readdir"), otherwise it
553 arrayref with "[$name, $type, $inode]" arrayrefs, each 744 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
554 describing a single directory entry in more detail. 745 describing a single directory entry in more detail.
555 746
556 $name is the name of the entry. 747 $name is the name of the entry.
557 748
558 $type is one of the "IO::AIO::DT_xxx" constants: 749 $type is one of the "IO::AIO::DT_xxx" constants:
571 unspecified content on systems that do not deliver the inode 762 unspecified content on systems that do not deliver the inode
572 information. 763 information.
573 764
574 IO::AIO::READDIR_DIRS_FIRST 765 IO::AIO::READDIR_DIRS_FIRST
575 When this flag is set, then the names will be returned in an 766 When this flag is set, then the names will be returned in an
576 order where likely directories come first. This is useful when 767 order where likely directories come first, in optimal stat
577 you need to quickly find directories, or you want to find all 768 order. This is useful when you need to quickly find directories,
578 directories while avoiding to stat() each entry. 769 or you want to find all directories while avoiding to stat()
770 each entry.
579 771
580 If the system returns type information in readdir, then this is 772 If the system returns type information in readdir, then this is
581 used to find directories directly. Otherwise, likely directories 773 used to find directories directly. Otherwise, likely directories
582 are files beginning with ".", or otherwise files with no dots, 774 are names beginning with ".", or otherwise names with no dots,
583 of which files with short names are tried first. 775 of which names with short names are tried first.
584 776
585 IO::AIO::READDIR_STAT_ORDER 777 IO::AIO::READDIR_STAT_ORDER
586 When this flag is set, then the names will be returned in an 778 When this flag is set, then the names will be returned in an
587 order suitable for stat()'ing each one. That is, when you plan 779 order suitable for stat()'ing each one. That is, when you plan
588 to stat() all files in the given directory, then the returned 780 to stat() all files in the given directory, then the returned
593 optimal stat order. 785 optimal stat order.
594 786
595 IO::AIO::READDIR_FOUND_UNKNOWN 787 IO::AIO::READDIR_FOUND_UNKNOWN
596 This flag should not be set when calling "aio_readdirx". 788 This flag should not be set when calling "aio_readdirx".
597 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
598 $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
599 flag therefore indicates that all $type's are known, which can 791 flag therefore indicates that all $type's are known, which can
600 be used to speed up some algorithms. 792 be used to speed up some algorithms.
601 793
602 aio_load $path, $data, $callback->($status) 794 aio_load $pathname, $data, $callback->($status)
603 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
604 into memory. Status is the same as with aio_read. 796 into memory. Status is the same as with aio_read.
605 797
606 aio_copy $srcpath, $dstpath, $callback->($status) 798 aio_copy $srcpath, $dstpath, $callback->($status)
607 Try to copy the *file* (directories not supported as either source 799 Try to copy the *file* (directories not supported as either source
624 816
625 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;
626 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"
627 and, if that is successful, unlinks the $srcpath. 819 and, if that is successful, unlinks the $srcpath.
628 820
629 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 821 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
630 Scans a directory (similar to "aio_readdir") but additionally tries 822 Scans a directory (similar to "aio_readdir") but additionally tries
631 to efficiently separate the entries of directory $path into two sets 823 to efficiently separate the entries of directory $path into two sets
632 of names, directories you can recurse into (directories), and ones 824 of names, directories you can recurse into (directories), and ones
633 you cannot recurse into (everything else, including symlinks to 825 you cannot recurse into (everything else, including symlinks to
634 directories). 826 directories).
667 Then entries will be sorted into likely directories a non-initial 859 Then entries will be sorted into likely directories a non-initial
668 dot currently) and likely non-directories (see "aio_readdirx"). Then 860 dot currently) and likely non-directories (see "aio_readdirx"). Then
669 every entry plus an appended "/." will be "stat"'ed, likely 861 every entry plus an appended "/." will be "stat"'ed, likely
670 directories first, in order of their inode numbers. If that 862 directories first, in order of their inode numbers. If that
671 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
672 directory (which will be checked seperately). This is often faster 864 directory (which will be checked separately). This is often faster
673 than stat'ing the entry itself because filesystems might detect the 865 than stat'ing the entry itself because filesystems might detect the
674 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
675 filetype feature), even on systems that cannot return the filetype 867 filetype feature), even on systems that cannot return the filetype
676 information on readdir. 868 information on readdir.
677 869
683 875
684 It will also likely work on non-POSIX filesystems with reduced 876 It will also likely work on non-POSIX filesystems with reduced
685 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
686 disables the directory counting heuristic. 878 disables the directory counting heuristic.
687 879
688 aio_rmtree $path, $callback->($status) 880 aio_rmtree $pathname, $callback->($status)
689 Delete a directory tree starting (and including) $path, return the 881 Delete a directory tree starting (and including) $path, return the
690 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
691 uses "aio_scandir" to recurse into and rmdir directories, and unlink 883 uses "aio_scandir" to recurse into and rmdir directories, and unlink
692 everything else. 884 everything else.
693 885
702 Asynchronously call fdatasync on the given filehandle and call the 894 Asynchronously call fdatasync on the given filehandle and call the
703 callback with the fdatasync result code. 895 callback with the fdatasync result code.
704 896
705 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
706 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.
707 905
708 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 906 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
709 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
710 to disk (but NOT the metadata), by calling the Linux-specific 908 to disk (but NOT the metadata), by calling the Linux-specific
711 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
715 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 913 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
716 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 914 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
717 "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
718 manpage for details. 916 manpage for details.
719 917
720 aio_pathsync $path, $callback->($status) 918 aio_pathsync $pathname, $callback->($status)
721 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
722 a composite request intended to sync directories after directory 920 a composite request intended to sync directories after directory
723 operations (E.g. rename). This might not work on all operating 921 operations (E.g. rename). This might not work on all operating
724 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
725 directory changes get written to disc. It works for anything that 923 directory changes get written to disc. It works for anything that
752 950
753 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
754 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
755 "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
756 reads all pages and ensures they are instantiated) or 954 reads all pages and ensures they are instantiated) or
757 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 955 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
758 and writing an octet from it, which dirties the page). 956 and writing an octet from it, which dirties the page).
759 957
760 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 958 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
761 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
762 mmap(2)ed scalars. 960 mmap(2)ed scalars.
794 992
795 Example: asynchronously lock all current and future pages into 993 Example: asynchronously lock all current and future pages into
796 memory. 994 memory.
797 995
798 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.
799 1045
800 aio_group $callback->(...) 1046 aio_group $callback->(...)
801 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
802 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
803 to bundle many requests into a single, composite, request with a 1049 to bundle many requests into a single, composite, request with a
837 While it is theoretically handy to have simple I/O scheduling 1083 While it is theoretically handy to have simple I/O scheduling
838 requests like sleep and file handle readable/writable, the overhead 1084 requests like sleep and file handle readable/writable, the overhead
839 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
840 not use this function except to put your application under 1086 not use this function except to put your application under
841 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.
842 1209
843 IO::AIO::REQ CLASS 1210 IO::AIO::REQ CLASS
844 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
845 called in non-void context. 1212 called in non-void context.
846 1213
946 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
947 attached generator that generates requests if idle. The idea behind 1314 attached generator that generates requests if idle. The idea behind
948 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
949 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
950 long time. For example, "aio_scandir" might generate hundreds of 1317 long time. For example, "aio_scandir" might generate hundreds of
951 thousands "aio_stat" requests, delaying any later requests for a 1318 thousands of "aio_stat" requests, delaying any later requests for a
952 long time. 1319 long time.
953 1320
954 To avoid this, and allow incremental generation of requests, you can 1321 To avoid this, and allow incremental generation of requests, you can
955 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
956 requests. The feed callback will be called whenever there are few 1323 requests. The feed callback will be called whenever there are few
998 results. 1365 results.
999 1366
1000 See "poll_cb" for an example. 1367 See "poll_cb" for an example.
1001 1368
1002 IO::AIO::poll_cb 1369 IO::AIO::poll_cb
1003 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
1004 this regularly. Returns 0 if all events could be processed, or -1 if 1371 have been executed but the results are not yet reported). You have
1005 it returned earlier for whatever reason. Returns immediately when no 1372 to call this "regularly" to finish outstanding requests.
1006 events are outstanding. The amount of events processed depends on
1007 the settings of "IO::AIO::max_poll_req" and
1008 "IO::AIO::max_poll_time".
1009 1373
1374 Returns 0 if all events could be processed (or there were no events
1375 to process), or -1 if it returned earlier for whatever reason.
1376 Returns immediately when no events are outstanding. The amount of
1377 events processed depends on the settings of "IO::AIO::max_poll_req",
1378 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1379
1010 If not all requests were processed for whatever reason, the 1380 If not all requests were processed for whatever reason, the poll
1011 filehandle will still be ready when "poll_cb" returns, so normally 1381 file descriptor will still be ready when "poll_cb" returns, so
1012 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.
1384
1385 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1386 becomes ready, it can be beneficial to call this function from loops
1387 which submit a lot of requests, to make sure the results get
1388 processed when they become available and not just when the loop is
1389 finished and the event loop takes over again. This function returns
1390 very fast when there are no outstanding requests.
1013 1391
1014 Example: Install an Event watcher that automatically calls 1392 Example: Install an Event watcher that automatically calls
1015 IO::AIO::poll_cb with high priority (more examples can be found in 1393 IO::AIO::poll_cb with high priority (more examples can be found in
1016 the SYNOPSIS section, at the top of this document): 1394 the SYNOPSIS section, at the top of this document):
1017 1395
1018 Event->io (fd => IO::AIO::poll_fileno, 1396 Event->io (fd => IO::AIO::poll_fileno,
1019 poll => 'r', async => 1, 1397 poll => 'r', async => 1,
1020 cb => \&IO::AIO::poll_cb); 1398 cb => \&IO::AIO::poll_cb);
1021 1399
1022 IO::AIO::poll_wait 1400 IO::AIO::poll_wait
1023 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
1024 phase, wait till the result filehandle becomes ready for reading 1402 requests are outstanding anymore.
1025 (simply does a "select" on the filehandle. This is useful if you 1403
1026 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.
1027 1406
1028 See "nreqs" for an example. 1407 See "nreqs" for an example.
1029 1408
1030 IO::AIO::poll 1409 IO::AIO::poll
1031 Waits until some requests have been handled. 1410 Waits until some requests have been handled.
1111 1490
1112 Under normal circumstances you don't need to call this function. 1491 Under normal circumstances you don't need to call this function.
1113 1492
1114 IO::AIO::max_idle $nthreads 1493 IO::AIO::max_idle $nthreads
1115 Limit the number of threads (default: 4) that are allowed to idle 1494 Limit the number of threads (default: 4) that are allowed to idle
1116 (i.e., threads that did not get a request to process within 10 1495 (i.e., threads that did not get a request to process within the idle
1117 seconds). That means if a thread becomes idle while $nthreads other 1496 timeout (default: 10 seconds). That means if a thread becomes idle
1118 threads are also idle, it will free its resources and exit. 1497 while $nthreads other threads are also idle, it will free its
1498 resources and exit.
1119 1499
1120 This is useful when you allow a large number of threads (e.g. 100 or 1500 This is useful when you allow a large number of threads (e.g. 100 or
1121 1000) to allow for extremely high load situations, but want to free 1501 1000) to allow for extremely high load situations, but want to free
1122 resources under normal circumstances (1000 threads can easily 1502 resources under normal circumstances (1000 threads can easily
1123 consume 30MB of RAM). 1503 consume 30MB of RAM).
1124 1504
1125 The default is probably ok in most situations, especially if thread 1505 The default is probably ok in most situations, especially if thread
1126 creation is fast. If thread creation is very slow on your system you 1506 creation is fast. If thread creation is very slow on your system you
1127 might want to use larger values. 1507 might want to use larger values.
1128 1508
1509 IO::AIO::idle_timeout $seconds
1510 Sets the minimum idle timeout (default 10) after which worker
1511 threads are allowed to exit. SEe "IO::AIO::max_idle".
1512
1129 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
1130 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
1131 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
1132 inexact: Better use an "aio_group" together with a feed callback. 1525 inexact: Better use an "aio_group" together with a feed callback.
1133 1526
1134 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
1135 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:
1136 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
1137 function will block until the limit is no longer exceeded.
1138 1529
1139 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
1140 the number of outstanding requests. 1546 no practical limit on the number of outstanding requests.
1141
1142 You can still queue as many requests as you want. Therefore,
1143 "max_outstanding" is mainly useful in simple scripts (with low
1144 values) or as a stop gap to shield against fatal memory overflow
1145 (with large values).
1146 1547
1147 STATISTICAL INFORMATION 1548 STATISTICAL INFORMATION
1148 IO::AIO::nreqs 1549 IO::AIO::nreqs
1149 Returns the number of requests currently in the ready, execute or 1550 Returns the number of requests currently in the ready, execute or
1150 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
1175 1576
1176 Returns the number of bytes copied, or -1 on error. 1577 Returns the number of bytes copied, or -1 on error.
1177 1578
1178 IO::AIO::fadvise $fh, $offset, $len, $advice 1579 IO::AIO::fadvise $fh, $offset, $len, $advice
1179 Simply calls the "posix_fadvise" function (see its manpage for 1580 Simply calls the "posix_fadvise" function (see its manpage for
1180 details). The following advice constants are avaiable: 1581 details). The following advice constants are available:
1181 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1582 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1182 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1583 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1183 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1584 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1184 1585
1185 On systems that do not implement "posix_fadvise", this function 1586 On systems that do not implement "posix_fadvise", this function
1186 returns ENOSYS, otherwise the return value of "posix_fadvise". 1587 returns ENOSYS, otherwise the return value of "posix_fadvise".
1187 1588
1188 IO::AIO::madvise $scalar, $offset, $len, $advice 1589 IO::AIO::madvise $scalar, $offset, $len, $advice
1189 Simply calls the "posix_madvise" function (see its manpage for 1590 Simply calls the "posix_madvise" function (see its manpage for
1190 details). The following advice constants are avaiable: 1591 details). The following advice constants are available:
1191 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1592 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1192 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1593 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1193 "IO::AIO::MADV_DONTNEED". 1594 "IO::AIO::MADV_DONTNEED".
1194 1595
1195 On systems that do not implement "posix_madvise", this function 1596 On systems that do not implement "posix_madvise", this function
1196 returns ENOSYS, otherwise the return value of "posix_madvise". 1597 returns ENOSYS, otherwise the return value of "posix_madvise".
1197 1598
1198 IO::AIO::mprotect $scalar, $offset, $len, $protect 1599 IO::AIO::mprotect $scalar, $offset, $len, $protect
1199 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1600 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1200 $scalar (see its manpage for details). The following protect 1601 $scalar (see its manpage for details). The following protect
1201 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1602 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1202 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1603 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1203 1604
1204 On systems that do not implement "mprotect", this function returns 1605 On systems that do not implement "mprotect", this function returns
1205 ENOSYS, otherwise the return value of "mprotect". 1606 ENOSYS, otherwise the return value of "mprotect".
1206 1607
1207 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1608 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1208 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
1209 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.
1210 1612
1211 The only operations allowed on the scalar are "substr"/"vec" that 1613 The only operations allowed on the scalar are "substr"/"vec" that
1212 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
1213 as copying it or searching it with regexes and so on. 1615 as copying it or searching it with regexes and so on.
1214 1616
1265 Calls the "munlockall" function. 1667 Calls the "munlockall" function.
1266 1668
1267 On systems that do not implement "munlockall", this function returns 1669 On systems that do not implement "munlockall", this function returns
1268 ENOSYS, otherwise the return value of "munlockall". 1670 ENOSYS, otherwise the return value of "munlockall".
1269 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
1270EVENT LOOP INTEGRATION 1690EVENT LOOP INTEGRATION
1271 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1691 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1272 automatically into many event loops: 1692 automatically into many event loops:
1273 1693
1274 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) 1694 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1296 # Danga::Socket integration 1716 # Danga::Socket integration
1297 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 1717 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1298 \&IO::AIO::poll_cb); 1718 \&IO::AIO::poll_cb);
1299 1719
1300 FORK BEHAVIOUR 1720 FORK BEHAVIOUR
1301 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.
1302 1728
1303 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
1304 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
1305 fork the parent simply leaves the quiescent state and continues 1731 supported, but using IO::AIO in the child is not.
1306 request/result processing, while the child frees the request/result
1307 queue (so that the requests started before the fork will only be handled
1308 in the parent). Threads will be started on demand until the limit set in
1309 the parent process has been reached again.
1310 1732
1311 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.
1312 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:
1313 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.
1314 1747
1315 MEMORY USAGE 1748 MEMORY USAGE
1316 Per-request usage: 1749 Per-request usage:
1317 1750
1318 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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