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Revision 1.46 by root, Sun Mar 27 10:26:08 2011 UTC vs.
Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC

64 64
65 EXAMPLE 65 EXAMPLE
66 This is a simple example that uses the EV module and loads /etc/passwd 66 This is a simple example that uses the EV module and loads /etc/passwd
67 asynchronously: 67 asynchronously:
68 68
69 use Fcntl;
70 use EV; 69 use EV;
71 use IO::AIO; 70 use IO::AIO;
72 71
73 # register the IO::AIO callback with EV 72 # register the IO::AIO callback with EV
74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 73 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
91 90
92 # file contents now in $contents 91 # file contents now in $contents
93 print $contents; 92 print $contents;
94 93
95 # exit event loop and program 94 # exit event loop and program
96 EV::unloop; 95 EV::break;
97 }; 96 };
98 }; 97 };
99 98
100 # possibly queue up other requests, or open GUI windows, 99 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 100 # check for sockets etc. etc.
102 101
103 # process events as long as there are some: 102 # process events as long as there are some:
104 EV::loop; 103 EV::run;
105 104
106REQUEST ANATOMY AND LIFETIME 105REQUEST ANATOMY AND LIFETIME
107 Every "aio_*" function creates a request. which is a C data structure 106 Every "aio_*" function creates a request. which is a C data structure
108 not directly visible to Perl. 107 not directly visible to Perl.
109 108
146 the actual aio request is severed and calling its methods will 145 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 146 either do nothing or result in a runtime error).
148 147
149FUNCTIONS 148FUNCTIONS
150 QUICK OVERVIEW 149 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 150 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 151 reference. See the following sections for function-by-function
153 documentation. 152 documentation.
154 153
154 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 155 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 156 aio_close $fh, $callback->($status)
157 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 158 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 159 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 160 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 161 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 162 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 163 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 164 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 165 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 166 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 168 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status) 169 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
170 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168 aio_unlink $pathname, $callback->($status) 171 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 172 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 173 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 174 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 175 aio_readlink $pathname, $callback->($link)
176 aio_realpath $pathname, $callback->($path)
173 aio_rename $srcpath, $dstpath, $callback->($status) 177 aio_rename $srcpath, $dstpath, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status) 178 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status) 179 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries) 180 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 181 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 182 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 183 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180 aio_load $path, $data, $callback->($status) 185 aio_load $pathname, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status) 186 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status) 187 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status) 188 aio_rmtree $pathname, $callback->($status)
189 aio_fcntl $fh, $cmd, $arg, $callback->($status)
190 aio_ioctl $fh, $request, $buf, $callback->($status)
185 aio_sync $callback->($status) 191 aio_sync $callback->($status)
192 aio_syncfs $fh, $callback->($status)
186 aio_fsync $fh, $callback->($status) 193 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status) 194 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 195 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status) 196 aio_pathsync $pathname, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 197 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 198 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 199 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status) 200 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...) 201 aio_group $callback->(...)
212 IO::AIO::nready 219 IO::AIO::nready
213 IO::AIO::npending 220 IO::AIO::npending
214 221
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count 222 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice 223 IO::AIO::fadvise $fh, $offset, $len, $advice
224 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
225 IO::AIO::munmap $scalar
217 IO::AIO::madvise $scalar, $offset, $length, $advice 226 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect 227 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef 228 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall 229 IO::AIO::munlockall
221 230
222 AIO REQUEST FUNCTIONS 231 API NOTES
223 All the "aio_*" calls are more or less thin wrappers around the syscall 232 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 233 with the same name (sans "aio_"). The arguments are similar or
225 identical, and they all accept an additional (and optional) $callback 234 identical, and they all accept an additional (and optional) $callback
226 argument which must be a code reference. This code reference will get 235 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. 236 called after the syscall has been executed in an asynchronous fashion.
237 The results of the request will be passed as arguments to the callback
238 (and, if an error occured, in $!) - for most requests the syscall return
239 code (e.g. most syscalls return -1 on error, unlike perl, which usually
240 delivers "false").
241
242 Some requests (such as "aio_readdir") pass the actual results and
243 communicate failures by passing "undef".
230 244
231 All functions expecting a filehandle keep a copy of the filehandle 245 All functions expecting a filehandle keep a copy of the filehandle
232 internally until the request has finished. 246 internally until the request has finished.
233 247
234 All functions return request objects of type IO::AIO::REQ that allow 248 All functions return request objects of type IO::AIO::REQ that allow
235 further manipulation of those requests while they are in-flight. 249 further manipulation of those requests while they are in-flight.
236 250
237 The pathnames you pass to these routines *must* be absolute and encoded 251 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 252 reason for this is that at the time the request is being executed, the
239 being executed, the current working directory could have changed. 253 current working directory could have changed. Alternatively, you can
240 Alternatively, you can make sure that you never change the current 254 make sure that you never change the current working directory anywhere
241 working directory anywhere in the program and then use relative paths. 255 in the program and then use relative paths. You can also take advantage
256 of IO::AIOs working directory abstraction, that lets you specify paths
257 relative to some previously-opened "working directory object" - see the
258 description of the "IO::AIO::WD" class later in this document.
242 259
243 To encode pathnames as octets, either make sure you either: a) always 260 To encode pathnames as octets, either make sure you either: a) always
244 pass in filenames you got from outside (command line, readdir etc.) 261 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 262 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 263 Encode module and encode your pathnames to the locale (or other)
247 the user environment, d) use Glib::filename_from_unicode on unicode 264 encoding in effect in the user environment, d) use
248 filenames or e) use something else to ensure your scalar has the correct 265 Glib::filename_from_unicode on unicode filenames or e) use something
249 contents. 266 else to ensure your scalar has the correct contents.
250 267
251 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 268 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
252 handles correctly whether it is set or not. 269 handles correctly whether it is set or not.
253 270
271 AIO REQUEST FUNCTIONS
254 $prev_pri = aioreq_pri [$pri] 272 $prev_pri = aioreq_pri [$pri]
255 Returns the priority value that would be used for the next request 273 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. 274 and, if $pri is given, sets the priority for the next aio request.
257 275
258 The default priority is 0, the minimum and maximum priorities are -4 276 The default priority is 0, the minimum and maximum priorities are -4
280 Similar to "aioreq_pri", but subtracts the given value from the 298 Similar to "aioreq_pri", but subtracts the given value from the
281 current priority, so the effect is cumulative. 299 current priority, so the effect is cumulative.
282 300
283 aio_open $pathname, $flags, $mode, $callback->($fh) 301 aio_open $pathname, $flags, $mode, $callback->($fh)
284 Asynchronously open or create a file and call the callback with a 302 Asynchronously open or create a file and call the callback with a
285 newly created filehandle for the file. 303 newly created filehandle for the file (or "undef" in case of an
304 error).
286 305
287 The pathname passed to "aio_open" must be absolute. See API NOTES, 306 The pathname passed to "aio_open" must be absolute. See API NOTES,
288 above, for an explanation. 307 above, for an explanation.
289 308
290 The $flags argument is a bitmask. See the "Fcntl" module for a list. 309 The $flags argument is a bitmask. See the "Fcntl" module for a list.
306 } else { 325 } else {
307 die "open failed: $!\n"; 326 die "open failed: $!\n";
308 } 327 }
309 }; 328 };
310 329
330 In addition to all the common open modes/flags ("O_RDONLY",
331 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
332 "O_APPEND"), the following POSIX and non-POSIX constants are
333 available (missing ones on your system are, as usual, 0):
334
335 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
336 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
337 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and
338 "O_TTY_INIT".
339
311 aio_close $fh, $callback->($status) 340 aio_close $fh, $callback->($status)
312 Asynchronously close a file and call the callback with the result 341 Asynchronously close a file and call the callback with the result
313 code. 342 code.
314 343
315 Unfortunately, you can't do this to perl. Perl *insists* very 344 Unfortunately, you can't do this to perl. Perl *insists* very
320 will use dup2 to overwrite the file descriptor with the write-end of 349 will use dup2 to overwrite the file descriptor with the write-end of
321 a pipe (the pipe fd will be created on demand and will be cached). 350 a pipe (the pipe fd will be created on demand and will be cached).
322 351
323 Or in other words: the file descriptor will be closed, but it will 352 Or in other words: the file descriptor will be closed, but it will
324 not be free for reuse until the perl filehandle is closed. 353 not be free for reuse until the perl filehandle is closed.
354
355 aio_seek $fh, $offset, $whence, $callback->($offs)
356 Seeks the filehandle to the new $offset, similarly to perl's
357 "sysseek". The $whence can use the traditional values (0 for
358 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
359 "IO::AIO::SEEK_END").
360
361 The resulting absolute offset will be passed to the callback, or -1
362 in case of an error.
363
364 In theory, the $whence constants could be different than the
365 corresponding values from Fcntl, but perl guarantees they are the
366 same, so don't panic.
367
368 As a GNU/Linux (and maybe Solaris) extension, also the constants
369 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
370 could be found. No guarantees about suitability for use in
371 "aio_seek" or Perl's "sysseek" can be made though, although I would
372 naively assume they "just work".
325 373
326 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
327 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
328 Reads or writes $length bytes from or to the specified $fh and 376 Reads or writes $length bytes from or to the specified $fh and
329 $offset into the scalar given by $data and offset $dataoffset and 377 $offset into the scalar given by $data and offset $dataoffset and
358 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 406 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
359 Tries to copy $length bytes from $in_fh to $out_fh. It starts 407 Tries to copy $length bytes from $in_fh to $out_fh. It starts
360 reading at byte offset $in_offset, and starts writing at the current 408 reading at byte offset $in_offset, and starts writing at the current
361 file offset of $out_fh. Because of that, it is not safe to issue 409 file offset of $out_fh. Because of that, it is not safe to issue
362 more than one "aio_sendfile" per $out_fh, as they will interfere 410 more than one "aio_sendfile" per $out_fh, as they will interfere
363 with each other. 411 with each other. The same $in_fh works fine though, as this function
412 does not move or use the file offset of $in_fh.
364 413
365 Please note that "aio_sendfile" can read more bytes from $in_fh than 414 Please note that "aio_sendfile" can read more bytes from $in_fh than
366 are written, and there is no way to find out how many bytes have 415 are written, and there is no way to find out how many more bytes
367 been read from "aio_sendfile" alone, as "aio_sendfile" only provides 416 have been read from "aio_sendfile" alone, as "aio_sendfile" only
368 the number of bytes written to $out_fh. Only if the result value 417 provides the number of bytes written to $out_fh. Only if the result
369 equals $length one can assume that $length bytes have been read. 418 value equals $length one can assume that $length bytes have been
419 read.
370 420
371 Unlike with other "aio_" functions, it makes a lot of sense to use 421 Unlike with other "aio_" functions, it makes a lot of sense to use
372 "aio_sendfile" on non-blocking sockets, as long as one end 422 "aio_sendfile" on non-blocking sockets, as long as one end
373 (typically the $in_fh) is a file - the file I/O will then be 423 (typically the $in_fh) is a file - the file I/O will then be
374 asynchronous, while the socket I/O will be non-blocking. Note, 424 asynchronous, while the socket I/O will be non-blocking. Note,
375 however, that you can run into a trap where "aio_sendfile" reads 425 however, that you can run into a trap where "aio_sendfile" reads
376 some data with readahead, then fails to write all data, and when the 426 some data with readahead, then fails to write all data, and when the
377 socket is ready the next time, the data in the cache is already 427 socket is ready the next time, the data in the cache is already
378 lost, forcing "aio_sendfile" to again hit the disk. Explicit 428 lost, forcing "aio_sendfile" to again hit the disk. Explicit
379 "aio_read" + "aio_write" let's you control resource usage much 429 "aio_read" + "aio_write" let's you better control resource usage.
380 better.
381 430
382 This call tries to make use of a native "sendfile" syscall to 431 This call tries to make use of a native "sendfile"-like syscall to
383 provide zero-copy operation. For this to work, $out_fh should refer 432 provide zero-copy operation. For this to work, $out_fh should refer
384 to a socket, and $in_fh should refer to an mmap'able file. 433 to a socket, and $in_fh should refer to an mmap'able file.
385 434
386 If a native sendfile cannot be found or it fails with "ENOSYS", 435 If a native sendfile cannot be found or it fails with "ENOSYS",
387 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", 436 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
388 it will be emulated, so you can call "aio_sendfile" on any type of 437 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
389 filehandle regardless of the limitations of the operating system. 438 any type of filehandle regardless of the limitations of the
439 operating system.
440
441 As native sendfile syscalls (as practically any non-POSIX interface
442 hacked together in a hurry to improve benchmark numbers) tend to be
443 rather buggy on many systems, this implementation tries to work
444 around some known bugs in Linux and FreeBSD kernels (probably
445 others, too), but that might fail, so you really really should check
446 the return value of "aio_sendfile" - fewre bytes than expected might
447 have been transferred.
390 448
391 aio_readahead $fh,$offset,$length, $callback->($retval) 449 aio_readahead $fh,$offset,$length, $callback->($retval)
392 "aio_readahead" populates the page cache with data from a file so 450 "aio_readahead" populates the page cache with data from a file so
393 that subsequent reads from that file will not block on disk I/O. The 451 that subsequent reads from that file will not block on disk I/O. The
394 $offset argument specifies the starting point from which data is to 452 $offset argument specifies the starting point from which data is to
474 namemax => 255, 532 namemax => 255,
475 frsize => 1024, 533 frsize => 1024,
476 fsid => 1810 534 fsid => 1810
477 } 535 }
478 536
537 Here is a (likely partial - send me updates!) list of fsid values
538 used by Linux - it is safe to hardcode these when $^O is "linux":
539
540 0x0000adf5 adfs
541 0x0000adff affs
542 0x5346414f afs
543 0x09041934 anon-inode filesystem
544 0x00000187 autofs
545 0x42465331 befs
546 0x1badface bfs
547 0x42494e4d binfmt_misc
548 0x9123683e btrfs
549 0x0027e0eb cgroupfs
550 0xff534d42 cifs
551 0x73757245 coda
552 0x012ff7b7 coh
553 0x28cd3d45 cramfs
554 0x453dcd28 cramfs-wend (wrong endianness)
555 0x64626720 debugfs
556 0x00001373 devfs
557 0x00001cd1 devpts
558 0x0000f15f ecryptfs
559 0x00414a53 efs
560 0x0000137d ext
561 0x0000ef53 ext2/ext3/ext4
562 0x0000ef51 ext2
563 0xf2f52010 f2fs
564 0x00004006 fat
565 0x65735546 fuseblk
566 0x65735543 fusectl
567 0x0bad1dea futexfs
568 0x01161970 gfs2
569 0x47504653 gpfs
570 0x00004244 hfs
571 0xf995e849 hpfs
572 0x00c0ffee hostfs
573 0x958458f6 hugetlbfs
574 0x2bad1dea inotifyfs
575 0x00009660 isofs
576 0x000072b6 jffs2
577 0x3153464a jfs
578 0x6b414653 k-afs
579 0x0bd00bd0 lustre
580 0x0000137f minix
581 0x0000138f minix 30 char names
582 0x00002468 minix v2
583 0x00002478 minix v2 30 char names
584 0x00004d5a minix v3
585 0x19800202 mqueue
586 0x00004d44 msdos
587 0x0000564c novell
588 0x00006969 nfs
589 0x6e667364 nfsd
590 0x00003434 nilfs
591 0x5346544e ntfs
592 0x00009fa1 openprom
593 0x7461636F ocfs2
594 0x00009fa0 proc
595 0x6165676c pstorefs
596 0x0000002f qnx4
597 0x68191122 qnx6
598 0x858458f6 ramfs
599 0x52654973 reiserfs
600 0x00007275 romfs
601 0x67596969 rpc_pipefs
602 0x73636673 securityfs
603 0xf97cff8c selinux
604 0x0000517b smb
605 0x534f434b sockfs
606 0x73717368 squashfs
607 0x62656572 sysfs
608 0x012ff7b6 sysv2
609 0x012ff7b5 sysv4
610 0x01021994 tmpfs
611 0x15013346 udf
612 0x00011954 ufs
613 0x54190100 ufs byteswapped
614 0x00009fa2 usbdevfs
615 0x01021997 v9fs
616 0xa501fcf5 vxfs
617 0xabba1974 xenfs
618 0x012ff7b4 xenix
619 0x58465342 xfs
620 0x012fd16d xia
621
479 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 622 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
480 Works like perl's "utime" function (including the special case of 623 Works like perl's "utime" function (including the special case of
481 $atime and $mtime being undef). Fractional times are supported if 624 $atime and $mtime being undef). Fractional times are supported if
482 the underlying syscalls support them. 625 the underlying syscalls support them.
483 626
505 aio_chown "path", 0, undef; 648 aio_chown "path", 0, undef;
506 649
507 aio_truncate $fh_or_path, $offset, $callback->($status) 650 aio_truncate $fh_or_path, $offset, $callback->($status)
508 Works like truncate(2) or ftruncate(2). 651 Works like truncate(2) or ftruncate(2).
509 652
653 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
654 Allocates or frees disk space according to the $mode argument. See
655 the linux "fallocate" documentation for details.
656
657 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
658 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
659 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
660
661 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
662 (without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range
663 (see your fallocate(2) manpage).
664
665 The file system block size used by "fallocate" is presumably the
666 "f_bsize" returned by "statvfs".
667
668 If "fallocate" isn't available or cannot be emulated (currently no
669 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
670
510 aio_chmod $fh_or_path, $mode, $callback->($status) 671 aio_chmod $fh_or_path, $mode, $callback->($status)
511 Works like perl's "chmod" function. 672 Works like perl's "chmod" function.
512 673
513 aio_unlink $pathname, $callback->($status) 674 aio_unlink $pathname, $callback->($status)
514 Asynchronously unlink (delete) a file and call the callback with the 675 Asynchronously unlink (delete) a file and call the callback with the
515 result code. 676 result code.
516 677
517 aio_mknod $path, $mode, $dev, $callback->($status) 678 aio_mknod $pathname, $mode, $dev, $callback->($status)
518 [EXPERIMENTAL] 679 [EXPERIMENTAL]
519 680
520 Asynchronously create a device node (or fifo). See mknod(2). 681 Asynchronously create a device node (or fifo). See mknod(2).
521 682
522 The only (POSIX-) portable way of calling this function is: 683 The only (POSIX-) portable way of calling this function is:
523 684
524 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 685 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
525 686
526 See "aio_stat" for info about some potentially helpful extra 687 See "aio_stat" for info about some potentially helpful extra
527 constants and functions. 688 constants and functions.
528 689
529 aio_link $srcpath, $dstpath, $callback->($status) 690 aio_link $srcpath, $dstpath, $callback->($status)
533 aio_symlink $srcpath, $dstpath, $callback->($status) 694 aio_symlink $srcpath, $dstpath, $callback->($status)
534 Asynchronously create a new symbolic link to the existing object at 695 Asynchronously create a new symbolic link to the existing object at
535 $srcpath at the path $dstpath and call the callback with the result 696 $srcpath at the path $dstpath and call the callback with the result
536 code. 697 code.
537 698
538 aio_readlink $path, $callback->($link) 699 aio_readlink $pathname, $callback->($link)
539 Asynchronously read the symlink specified by $path and pass it to 700 Asynchronously read the symlink specified by $path and pass it to
540 the callback. If an error occurs, nothing or undef gets passed to 701 the callback. If an error occurs, nothing or undef gets passed to
541 the callback. 702 the callback.
542 703
704 aio_realpath $pathname, $callback->($path)
705 Asynchronously make the path absolute and resolve any symlinks in
706 $path. The resulting path only consists of directories (same as
707 Cwd::realpath).
708
709 This request can be used to get the absolute path of the current
710 working directory by passing it a path of . (a single dot).
711
543 aio_rename $srcpath, $dstpath, $callback->($status) 712 aio_rename $srcpath, $dstpath, $callback->($status)
544 Asynchronously rename the object at $srcpath to $dstpath, just as 713 Asynchronously rename the object at $srcpath to $dstpath, just as
545 rename(2) and call the callback with the result code. 714 rename(2) and call the callback with the result code.
715
716 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd.
546 719
547 aio_mkdir $pathname, $mode, $callback->($status) 720 aio_mkdir $pathname, $mode, $callback->($status)
548 Asynchronously mkdir (create) a directory and call the callback with 721 Asynchronously mkdir (create) a directory and call the callback with
549 the result code. $mode will be modified by the umask at the time the 722 the result code. $mode will be modified by the umask at the time the
550 request is executed, so do not change your umask. 723 request is executed, so do not change your umask.
551 724
552 aio_rmdir $pathname, $callback->($status) 725 aio_rmdir $pathname, $callback->($status)
553 Asynchronously rmdir (delete) a directory and call the callback with 726 Asynchronously rmdir (delete) a directory and call the callback with
554 the result code. 727 the result code.
555 728
729 On systems that support the AIO::WD working directory abstraction
730 natively, the case "[$wd, "."]" is specialcased - instead of
731 failing, "rmdir" is called on the absolute path of $wd.
732
556 aio_readdir $pathname, $callback->($entries) 733 aio_readdir $pathname, $callback->($entries)
557 Unlike the POSIX call of the same name, "aio_readdir" reads an 734 Unlike the POSIX call of the same name, "aio_readdir" reads an
558 entire directory (i.e. opendir + readdir + closedir). The entries 735 entire directory (i.e. opendir + readdir + closedir). The entries
559 will not be sorted, and will NOT include the "." and ".." entries. 736 will not be sorted, and will NOT include the "." and ".." entries.
560 737
561 The callback is passed a single argument which is either "undef" or 738 The callback is passed a single argument which is either "undef" or
562 an array-ref with the filenames. 739 an array-ref with the filenames.
563 740
564 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 741 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
565 Quite similar to "aio_readdir", but the $flags argument allows to 742 Quite similar to "aio_readdir", but the $flags argument allows one
566 tune behaviour and output format. In case of an error, $entries will 743 to tune behaviour and output format. In case of an error, $entries
567 be "undef". 744 will be "undef".
568 745
569 The flags are a combination of the following constants, ORed 746 The flags are a combination of the following constants, ORed
570 together (the flags will also be passed to the callback, possibly 747 together (the flags will also be passed to the callback, possibly
571 modified): 748 modified):
572 749
573 IO::AIO::READDIR_DENTS 750 IO::AIO::READDIR_DENTS
574 When this flag is off, then the callback gets an arrayref with 751 When this flag is off, then the callback gets an arrayref
575 of names only (as with "aio_readdir"), otherwise it gets an 752 consisting of names only (as with "aio_readdir"), otherwise it
576 arrayref with "[$name, $type, $inode]" arrayrefs, each 753 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
577 describing a single directory entry in more detail. 754 describing a single directory entry in more detail.
578 755
579 $name is the name of the entry. 756 $name is the name of the entry.
580 757
581 $type is one of the "IO::AIO::DT_xxx" constants: 758 $type is one of the "IO::AIO::DT_xxx" constants:
594 unspecified content on systems that do not deliver the inode 771 unspecified content on systems that do not deliver the inode
595 information. 772 information.
596 773
597 IO::AIO::READDIR_DIRS_FIRST 774 IO::AIO::READDIR_DIRS_FIRST
598 When this flag is set, then the names will be returned in an 775 When this flag is set, then the names will be returned in an
599 order where likely directories come first. This is useful when 776 order where likely directories come first, in optimal stat
600 you need to quickly find directories, or you want to find all 777 order. This is useful when you need to quickly find directories,
601 directories while avoiding to stat() each entry. 778 or you want to find all directories while avoiding to stat()
779 each entry.
602 780
603 If the system returns type information in readdir, then this is 781 If the system returns type information in readdir, then this is
604 used to find directories directly. Otherwise, likely directories 782 used to find directories directly. Otherwise, likely directories
605 are files beginning with ".", or otherwise files with no dots, 783 are names beginning with ".", or otherwise names with no dots,
606 of which files with short names are tried first. 784 of which names with short names are tried first.
607 785
608 IO::AIO::READDIR_STAT_ORDER 786 IO::AIO::READDIR_STAT_ORDER
609 When this flag is set, then the names will be returned in an 787 When this flag is set, then the names will be returned in an
610 order suitable for stat()'ing each one. That is, when you plan 788 order suitable for stat()'ing each one. That is, when you plan
611 to stat() all files in the given directory, then the returned 789 to stat() all files in the given directory, then the returned
616 optimal stat order. 794 optimal stat order.
617 795
618 IO::AIO::READDIR_FOUND_UNKNOWN 796 IO::AIO::READDIR_FOUND_UNKNOWN
619 This flag should not be set when calling "aio_readdirx". 797 This flag should not be set when calling "aio_readdirx".
620 Instead, it is being set by "aio_readdirx", when any of the 798 Instead, it is being set by "aio_readdirx", when any of the
621 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 799 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
622 flag therefore indicates that all $type's are known, which can 800 flag therefore indicates that all $type's are known, which can
623 be used to speed up some algorithms. 801 be used to speed up some algorithms.
624 802
625 aio_load $path, $data, $callback->($status) 803 aio_load $pathname, $data, $callback->($status)
626 This is a composite request that tries to fully load the given file 804 This is a composite request that tries to fully load the given file
627 into memory. Status is the same as with aio_read. 805 into memory. Status is the same as with aio_read.
628 806
629 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
630 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
647 825
648 This is a composite request that tries to rename(2) the file first; 826 This is a composite request that tries to rename(2) the file first;
649 if rename fails with "EXDEV", it copies the file with "aio_copy" 827 if rename fails with "EXDEV", it copies the file with "aio_copy"
650 and, if that is successful, unlinks the $srcpath. 828 and, if that is successful, unlinks the $srcpath.
651 829
652 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 830 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
653 Scans a directory (similar to "aio_readdir") but additionally tries 831 Scans a directory (similar to "aio_readdir") but additionally tries
654 to efficiently separate the entries of directory $path into two sets 832 to efficiently separate the entries of directory $path into two sets
655 of names, directories you can recurse into (directories), and ones 833 of names, directories you can recurse into (directories), and ones
656 you cannot recurse into (everything else, including symlinks to 834 you cannot recurse into (everything else, including symlinks to
657 directories). 835 directories).
690 Then entries will be sorted into likely directories a non-initial 868 Then entries will be sorted into likely directories a non-initial
691 dot currently) and likely non-directories (see "aio_readdirx"). Then 869 dot currently) and likely non-directories (see "aio_readdirx"). Then
692 every entry plus an appended "/." will be "stat"'ed, likely 870 every entry plus an appended "/." will be "stat"'ed, likely
693 directories first, in order of their inode numbers. If that 871 directories first, in order of their inode numbers. If that
694 succeeds, it assumes that the entry is a directory or a symlink to 872 succeeds, it assumes that the entry is a directory or a symlink to
695 directory (which will be checked seperately). This is often faster 873 directory (which will be checked separately). This is often faster
696 than stat'ing the entry itself because filesystems might detect the 874 than stat'ing the entry itself because filesystems might detect the
697 type of the entry without reading the inode data (e.g. ext2fs 875 type of the entry without reading the inode data (e.g. ext2fs
698 filetype feature), even on systems that cannot return the filetype 876 filetype feature), even on systems that cannot return the filetype
699 information on readdir. 877 information on readdir.
700 878
706 884
707 It will also likely work on non-POSIX filesystems with reduced 885 It will also likely work on non-POSIX filesystems with reduced
708 efficiency as those tend to return 0 or 1 as link counts, which 886 efficiency as those tend to return 0 or 1 as link counts, which
709 disables the directory counting heuristic. 887 disables the directory counting heuristic.
710 888
711 aio_rmtree $path, $callback->($status) 889 aio_rmtree $pathname, $callback->($status)
712 Delete a directory tree starting (and including) $path, return the 890 Delete a directory tree starting (and including) $path, return the
713 status of the final "rmdir" only. This is a composite request that 891 status of the final "rmdir" only. This is a composite request that
714 uses "aio_scandir" to recurse into and rmdir directories, and unlink 892 uses "aio_scandir" to recurse into and rmdir directories, and unlink
715 everything else. 893 everything else.
716 894
895 aio_fcntl $fh, $cmd, $arg, $callback->($status)
896 aio_ioctl $fh, $request, $buf, $callback->($status)
897 These work just like the "fcntl" and "ioctl" built-in functions,
898 except they execute asynchronously and pass the return value to the
899 callback.
900
901 Both calls can be used for a lot of things, some of which make more
902 sense to run asynchronously in their own thread, while some others
903 make less sense. For example, calls that block waiting for external
904 events, such as locking, will also lock down an I/O thread while it
905 is waiting, which can deadlock the whole I/O system. At the same
906 time, there might be no alternative to using a thread to wait.
907
908 So in general, you should only use these calls for things that do
909 (filesystem) I/O, not for things that wait for other events
910 (network, other processes), although if you are careful and know
911 what you are doing, you still can.
912
717 aio_sync $callback->($status) 913 aio_sync $callback->($status)
718 Asynchronously call sync and call the callback when finished. 914 Asynchronously call sync and call the callback when finished.
719 915
720 aio_fsync $fh, $callback->($status) 916 aio_fsync $fh, $callback->($status)
721 Asynchronously call fsync on the given filehandle and call the 917 Asynchronously call fsync on the given filehandle and call the
725 Asynchronously call fdatasync on the given filehandle and call the 921 Asynchronously call fdatasync on the given filehandle and call the
726 callback with the fdatasync result code. 922 callback with the fdatasync result code.
727 923
728 If this call isn't available because your OS lacks it or it couldn't 924 If this call isn't available because your OS lacks it or it couldn't
729 be detected, it will be emulated by calling "fsync" instead. 925 be detected, it will be emulated by calling "fsync" instead.
926
927 aio_syncfs $fh, $callback->($status)
928 Asynchronously call the syncfs syscall to sync the filesystem
929 associated to the given filehandle and call the callback with the
930 syncfs result code. If syncfs is not available, calls sync(), but
931 returns -1 and sets errno to "ENOSYS" nevertheless.
730 932
731 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 933 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
732 Sync the data portion of the file specified by $offset and $length 934 Sync the data portion of the file specified by $offset and $length
733 to disk (but NOT the metadata), by calling the Linux-specific 935 to disk (but NOT the metadata), by calling the Linux-specific
734 sync_file_range call. If sync_file_range is not available or it 936 sync_file_range call. If sync_file_range is not available or it
738 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 940 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
739 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 941 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
740 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 942 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
741 manpage for details. 943 manpage for details.
742 944
743 aio_pathsync $path, $callback->($status) 945 aio_pathsync $pathname, $callback->($status)
744 This request tries to open, fsync and close the given path. This is 946 This request tries to open, fsync and close the given path. This is
745 a composite request intended to sync directories after directory 947 a composite request intended to sync directories after directory
746 operations (E.g. rename). This might not work on all operating 948 operations (E.g. rename). This might not work on all operating
747 systems or have any specific effect, but usually it makes sure that 949 systems or have any specific effect, but usually it makes sure that
748 directory changes get written to disc. It works for anything that 950 directory changes get written to disc. It works for anything that
775 977
776 It touches (reads or writes) all memory pages in the specified range 978 It touches (reads or writes) all memory pages in the specified range
777 inside the scalar. All caveats and parameters are the same as for 979 inside the scalar. All caveats and parameters are the same as for
778 "aio_msync", above, except for flags, which must be either 0 (which 980 "aio_msync", above, except for flags, which must be either 0 (which
779 reads all pages and ensures they are instantiated) or 981 reads all pages and ensures they are instantiated) or
780 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 982 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
781 and writing an octet from it, which dirties the page). 983 and writing an octet from it, which dirties the page).
782 984
783 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 985 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
784 This is a rather advanced IO::AIO call, which works best on 986 This is a rather advanced IO::AIO call, which works best on
785 mmap(2)ed scalars. 987 mmap(2)ed scalars.
817 1019
818 Example: asynchronously lock all current and future pages into 1020 Example: asynchronously lock all current and future pages into
819 memory. 1021 memory.
820 1022
821 aio_mlockall IO::AIO::MCL_FUTURE; 1023 aio_mlockall IO::AIO::MCL_FUTURE;
1024
1025 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1026 Queries the extents of the given file (by calling the Linux "FIEMAP"
1027 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1028 details). If the ioctl is not available on your OS, then this
1029 request will fail with "ENOSYS".
1030
1031 $start is the starting offset to query extents for, $length is the
1032 size of the range to query - if it is "undef", then the whole file
1033 will be queried.
1034
1035 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1036 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1037 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1038 query the data portion.
1039
1040 $count is the maximum number of extent records to return. If it is
1041 "undef", then IO::AIO queries all extents of the range. As a very
1042 special case, if it is 0, then the callback receives the number of
1043 extents instead of the extents themselves (which is unreliable, see
1044 below).
1045
1046 If an error occurs, the callback receives no arguments. The special
1047 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1048
1049 Otherwise, the callback receives an array reference with extent
1050 structures. Each extent structure is an array reference itself, with
1051 the following members:
1052
1053 [$logical, $physical, $length, $flags]
1054
1055 Flags is any combination of the following flag values (typically
1056 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1057
1058 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1059 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1060 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1061 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1062 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1063 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1064 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1065 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1066
1067 At the time of this writing (Linux 3.2), this requets is unreliable
1068 unless $count is "undef", as the kernel has all sorts of bugs
1069 preventing it to return all extents of a range for files with large
1070 number of extents. The code works around all these issues if $count
1071 is undef.
822 1072
823 aio_group $callback->(...) 1073 aio_group $callback->(...)
824 This is a very special aio request: Instead of doing something, it 1074 This is a very special aio request: Instead of doing something, it
825 is a container for other aio requests, which is useful if you want 1075 is a container for other aio requests, which is useful if you want
826 to bundle many requests into a single, composite, request with a 1076 to bundle many requests into a single, composite, request with a
860 While it is theoretically handy to have simple I/O scheduling 1110 While it is theoretically handy to have simple I/O scheduling
861 requests like sleep and file handle readable/writable, the overhead 1111 requests like sleep and file handle readable/writable, the overhead
862 this creates is immense (it blocks a thread for a long time) so do 1112 this creates is immense (it blocks a thread for a long time) so do
863 not use this function except to put your application under 1113 not use this function except to put your application under
864 artificial I/O pressure. 1114 artificial I/O pressure.
1115
1116 IO::AIO::WD - multiple working directories
1117 Your process only has one current working directory, which is used by
1118 all threads. This makes it hard to use relative paths (some other
1119 component could call "chdir" at any time, and it is hard to control when
1120 the path will be used by IO::AIO).
1121
1122 One solution for this is to always use absolute paths. This usually
1123 works, but can be quite slow (the kernel has to walk the whole path on
1124 every access), and can also be a hassle to implement.
1125
1126 Newer POSIX systems have a number of functions (openat, fdopendir,
1127 futimensat and so on) that make it possible to specify working
1128 directories per operation.
1129
1130 For portability, and because the clowns who "designed", or shall I
1131 write, perpetrated this new interface were obviously half-drunk, this
1132 abstraction cannot be perfect, though.
1133
1134 IO::AIO allows you to convert directory paths into a so-called
1135 IO::AIO::WD object. This object stores the canonicalised, absolute
1136 version of the path, and on systems that allow it, also a directory file
1137 descriptor.
1138
1139 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1140 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1141 object and a pathname instead (or the IO::AIO::WD object alone, which
1142 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1143 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1144 relative to that IO::AIO::WD object.
1145
1146 For example, to get a wd object for /etc and then stat passwd inside,
1147 you would write:
1148
1149 aio_wd "/etc", sub {
1150 my $etcdir = shift;
1151
1152 # although $etcdir can be undef on error, there is generally no reason
1153 # to check for errors here, as aio_stat will fail with ENOENT
1154 # when $etcdir is undef.
1155
1156 aio_stat [$etcdir, "passwd"], sub {
1157 # yay
1158 };
1159 };
1160
1161 The fact that "aio_wd" is a request and not a normal function shows that
1162 creating an IO::AIO::WD object is itself a potentially blocking
1163 operation, which is why it is done asynchronously.
1164
1165 To stat the directory obtained with "aio_wd" above, one could write
1166 either of the following three request calls:
1167
1168 aio_lstat "/etc" , sub { ... # pathname as normal string
1169 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1170 aio_lstat $wd , sub { ... # shorthand for the previous
1171
1172 As with normal pathnames, IO::AIO keeps a copy of the working directory
1173 object and the pathname string, so you could write the following without
1174 causing any issues due to $path getting reused:
1175
1176 my $path = [$wd, undef];
1177
1178 for my $name (qw(abc def ghi)) {
1179 $path->[1] = $name;
1180 aio_stat $path, sub {
1181 # ...
1182 };
1183 }
1184
1185 There are some caveats: when directories get renamed (or deleted), the
1186 pathname string doesn't change, so will point to the new directory (or
1187 nowhere at all), while the directory fd, if available on the system,
1188 will still point to the original directory. Most functions accepting a
1189 pathname will use the directory fd on newer systems, and the string on
1190 older systems. Some functions (such as realpath) will always rely on the
1191 string form of the pathname.
1192
1193 So this functionality is mainly useful to get some protection against
1194 "chdir", to easily get an absolute path out of a relative path for
1195 future reference, and to speed up doing many operations in the same
1196 directory (e.g. when stat'ing all files in a directory).
1197
1198 The following functions implement this working directory abstraction:
1199
1200 aio_wd $pathname, $callback->($wd)
1201 Asynchonously canonicalise the given pathname and convert it to an
1202 IO::AIO::WD object representing it. If possible and supported on the
1203 system, also open a directory fd to speed up pathname resolution
1204 relative to this working directory.
1205
1206 If something goes wrong, then "undef" is passwd to the callback
1207 instead of a working directory object and $! is set appropriately.
1208 Since passing "undef" as working directory component of a pathname
1209 fails the request with "ENOENT", there is often no need for error
1210 checking in the "aio_wd" callback, as future requests using the
1211 value will fail in the expected way.
1212
1213 IO::AIO::CWD
1214 This is a compiletime constant (object) that represents the process
1215 current working directory.
1216
1217 Specifying this object as working directory object for a pathname is
1218 as if the pathname would be specified directly, without a directory
1219 object. For example, these calls are functionally identical:
1220
1221 aio_stat "somefile", sub { ... };
1222 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1223
1224 To recover the path associated with an IO::AIO::WD object, you can use
1225 "aio_realpath":
1226
1227 aio_realpath $wd, sub {
1228 warn "path is $_[0]\n";
1229 };
1230
1231 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1232 sometimes, fall back to using an absolue path.
865 1233
866 IO::AIO::REQ CLASS 1234 IO::AIO::REQ CLASS
867 All non-aggregate "aio_*" functions return an object of this class when 1235 All non-aggregate "aio_*" functions return an object of this class when
868 called in non-void context. 1236 called in non-void context.
869 1237
969 Sets a feeder/generator on this group: every group can have an 1337 Sets a feeder/generator on this group: every group can have an
970 attached generator that generates requests if idle. The idea behind 1338 attached generator that generates requests if idle. The idea behind
971 this is that, although you could just queue as many requests as you 1339 this is that, although you could just queue as many requests as you
972 want in a group, this might starve other requests for a potentially 1340 want in a group, this might starve other requests for a potentially
973 long time. For example, "aio_scandir" might generate hundreds of 1341 long time. For example, "aio_scandir" might generate hundreds of
974 thousands "aio_stat" requests, delaying any later requests for a 1342 thousands of "aio_stat" requests, delaying any later requests for a
975 long time. 1343 long time.
976 1344
977 To avoid this, and allow incremental generation of requests, you can 1345 To avoid this, and allow incremental generation of requests, you can
978 instead a group and set a feeder on it that generates those 1346 instead a group and set a feeder on it that generates those
979 requests. The feed callback will be called whenever there are few 1347 requests. The feed callback will be called whenever there are few
1021 results. 1389 results.
1022 1390
1023 See "poll_cb" for an example. 1391 See "poll_cb" for an example.
1024 1392
1025 IO::AIO::poll_cb 1393 IO::AIO::poll_cb
1026 Process some outstanding events on the result pipe. You have to call 1394 Process some requests that have reached the result phase (i.e. they
1027 this regularly. Returns 0 if all events could be processed, or -1 if 1395 have been executed but the results are not yet reported). You have
1028 it returned earlier for whatever reason. Returns immediately when no 1396 to call this "regularly" to finish outstanding requests.
1029 events are outstanding. The amount of events processed depends on
1030 the settings of "IO::AIO::max_poll_req" and
1031 "IO::AIO::max_poll_time".
1032 1397
1398 Returns 0 if all events could be processed (or there were no events
1399 to process), or -1 if it returned earlier for whatever reason.
1400 Returns immediately when no events are outstanding. The amount of
1401 events processed depends on the settings of "IO::AIO::max_poll_req",
1402 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1403
1033 If not all requests were processed for whatever reason, the 1404 If not all requests were processed for whatever reason, the poll
1034 filehandle will still be ready when "poll_cb" returns, so normally 1405 file descriptor will still be ready when "poll_cb" returns, so
1035 you don't have to do anything special to have it called later. 1406 normally you don't have to do anything special to have it called
1407 later.
1408
1409 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1410 becomes ready, it can be beneficial to call this function from loops
1411 which submit a lot of requests, to make sure the results get
1412 processed when they become available and not just when the loop is
1413 finished and the event loop takes over again. This function returns
1414 very fast when there are no outstanding requests.
1036 1415
1037 Example: Install an Event watcher that automatically calls 1416 Example: Install an Event watcher that automatically calls
1038 IO::AIO::poll_cb with high priority (more examples can be found in 1417 IO::AIO::poll_cb with high priority (more examples can be found in
1039 the SYNOPSIS section, at the top of this document): 1418 the SYNOPSIS section, at the top of this document):
1040 1419
1041 Event->io (fd => IO::AIO::poll_fileno, 1420 Event->io (fd => IO::AIO::poll_fileno,
1042 poll => 'r', async => 1, 1421 poll => 'r', async => 1,
1043 cb => \&IO::AIO::poll_cb); 1422 cb => \&IO::AIO::poll_cb);
1044 1423
1045 IO::AIO::poll_wait 1424 IO::AIO::poll_wait
1046 If there are any outstanding requests and none of them in the result 1425 Wait until either at least one request is in the result phase or no
1047 phase, wait till the result filehandle becomes ready for reading 1426 requests are outstanding anymore.
1048 (simply does a "select" on the filehandle. This is useful if you 1427
1049 want to synchronously wait for some requests to finish). 1428 This is useful if you want to synchronously wait for some requests
1429 to become ready, without actually handling them.
1050 1430
1051 See "nreqs" for an example. 1431 See "nreqs" for an example.
1052 1432
1053 IO::AIO::poll 1433 IO::AIO::poll
1054 Waits until some requests have been handled. 1434 Waits until some requests have been handled.
1153 IO::AIO::idle_timeout $seconds 1533 IO::AIO::idle_timeout $seconds
1154 Sets the minimum idle timeout (default 10) after which worker 1534 Sets the minimum idle timeout (default 10) after which worker
1155 threads are allowed to exit. SEe "IO::AIO::max_idle". 1535 threads are allowed to exit. SEe "IO::AIO::max_idle".
1156 1536
1157 IO::AIO::max_outstanding $maxreqs 1537 IO::AIO::max_outstanding $maxreqs
1538 Sets the maximum number of outstanding requests to $nreqs. If you do
1539 queue up more than this number of requests, the next call to
1540 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
1541 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1542 no longer exceeded.
1543
1544 In other words, this setting does not enforce a queue limit, but can
1545 be used to make poll functions block if the limit is exceeded.
1546
1158 This is a very bad function to use in interactive programs because 1547 This is a very bad function to use in interactive programs because
1159 it blocks, and a bad way to reduce concurrency because it is 1548 it blocks, and a bad way to reduce concurrency because it is
1160 inexact: Better use an "aio_group" together with a feed callback. 1549 inexact: Better use an "aio_group" together with a feed callback.
1161 1550
1162 Sets the maximum number of outstanding requests to $nreqs. If you do 1551 Its main use is in scripts without an event loop - when you want to
1163 queue up more than this number of requests, the next call to the 1552 stat a lot of files, you can write somehting like this:
1164 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
1165 function will block until the limit is no longer exceeded.
1166 1553
1167 The default value is very large, so there is no practical limit on 1554 IO::AIO::max_outstanding 32;
1555
1556 for my $path (...) {
1557 aio_stat $path , ...;
1558 IO::AIO::poll_cb;
1559 }
1560
1561 IO::AIO::flush;
1562
1563 The call to "poll_cb" inside the loop will normally return
1564 instantly, but as soon as more thna 32 reqeusts are in-flight, it
1565 will block until some requests have been handled. This keeps the
1566 loop from pushing a large number of "aio_stat" requests onto the
1567 queue.
1568
1569 The default value for "max_outstanding" is very large, so there is
1168 the number of outstanding requests. 1570 no practical limit on the number of outstanding requests.
1169
1170 You can still queue as many requests as you want. Therefore,
1171 "max_outstanding" is mainly useful in simple scripts (with low
1172 values) or as a stop gap to shield against fatal memory overflow
1173 (with large values).
1174 1571
1175 STATISTICAL INFORMATION 1572 STATISTICAL INFORMATION
1176 IO::AIO::nreqs 1573 IO::AIO::nreqs
1177 Returns the number of requests currently in the ready, execute or 1574 Returns the number of requests currently in the ready, execute or
1178 pending states (i.e. for which their callback has not been invoked 1575 pending states (i.e. for which their callback has not been invoked
1190 IO::AIO::npending 1587 IO::AIO::npending
1191 Returns the number of requests currently in the pending state 1588 Returns the number of requests currently in the pending state
1192 (executed, but not yet processed by poll_cb). 1589 (executed, but not yet processed by poll_cb).
1193 1590
1194 MISCELLANEOUS FUNCTIONS 1591 MISCELLANEOUS FUNCTIONS
1195 IO::AIO implements some functions that might be useful, but are not 1592 IO::AIO implements some functions that are useful when you want to use
1196 asynchronous. 1593 some "Advanced I/O" function not available to in Perl, without going the
1594 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1595 counterpart.
1197 1596
1198 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1199 Calls the "eio_sendfile_sync" function, which is like 1598 Calls the "eio_sendfile_sync" function, which is like
1200 "aio_sendfile", but is blocking (this makes most sense if you know 1599 "aio_sendfile", but is blocking (this makes most sense if you know
1201 the input data is likely cached already and the output filehandle is 1600 the input data is likely cached already and the output filehandle is
1203 1602
1204 Returns the number of bytes copied, or -1 on error. 1603 Returns the number of bytes copied, or -1 on error.
1205 1604
1206 IO::AIO::fadvise $fh, $offset, $len, $advice 1605 IO::AIO::fadvise $fh, $offset, $len, $advice
1207 Simply calls the "posix_fadvise" function (see its manpage for 1606 Simply calls the "posix_fadvise" function (see its manpage for
1208 details). The following advice constants are avaiable: 1607 details). The following advice constants are available:
1209 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1608 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1210 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1609 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1211 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1610 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1212 1611
1213 On systems that do not implement "posix_fadvise", this function 1612 On systems that do not implement "posix_fadvise", this function
1214 returns ENOSYS, otherwise the return value of "posix_fadvise". 1613 returns ENOSYS, otherwise the return value of "posix_fadvise".
1215 1614
1216 IO::AIO::madvise $scalar, $offset, $len, $advice 1615 IO::AIO::madvise $scalar, $offset, $len, $advice
1217 Simply calls the "posix_madvise" function (see its manpage for 1616 Simply calls the "posix_madvise" function (see its manpage for
1218 details). The following advice constants are avaiable: 1617 details). The following advice constants are available:
1219 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1618 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1220 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1619 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1221 "IO::AIO::MADV_DONTNEED". 1620 "IO::AIO::MADV_DONTNEED".
1222 1621
1223 On systems that do not implement "posix_madvise", this function 1622 On systems that do not implement "posix_madvise", this function
1224 returns ENOSYS, otherwise the return value of "posix_madvise". 1623 returns ENOSYS, otherwise the return value of "posix_madvise".
1225 1624
1226 IO::AIO::mprotect $scalar, $offset, $len, $protect 1625 IO::AIO::mprotect $scalar, $offset, $len, $protect
1227 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1626 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1228 $scalar (see its manpage for details). The following protect 1627 $scalar (see its manpage for details). The following protect
1229 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1628 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1230 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1629 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1231 1630
1232 On systems that do not implement "mprotect", this function returns 1631 On systems that do not implement "mprotect", this function returns
1233 ENOSYS, otherwise the return value of "mprotect". 1632 ENOSYS, otherwise the return value of "mprotect".
1234 1633
1235 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1236 Memory-maps a file (or anonymous memory range) and attaches it to 1635 Memory-maps a file (or anonymous memory range) and attaches it to
1237 the given $scalar, which will act like a string scalar. 1636 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise.
1238 1638
1239 The only operations allowed on the scalar are "substr"/"vec" that 1639 The only operations allowed on the scalar are "substr"/"vec" that
1240 don't change the string length, and most read-only operations such 1640 don't change the string length, and most read-only operations such
1241 as copying it or searching it with regexes and so on. 1641 as copying it or searching it with regexes and so on.
1242 1642
1256 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1656 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1257 "IO::AIO::PROT_WRITE", 1657 "IO::AIO::PROT_WRITE",
1258 1658
1259 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1659 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1260 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1660 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1261 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1661 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1262 (which is set to "MAP_ANON" if your system only provides this 1662 "MAP_ANON" if your system only provides this constant),
1663 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1263 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1664 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1665 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1264 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1666 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1265 "IO::AIO::MAP_NONBLOCK" 1667 "IO::AIO::MAP_STACK".
1266 1668
1267 If $fh is "undef", then a file descriptor of -1 is passed. 1669 If $fh is "undef", then a file descriptor of -1 is passed.
1268 1670
1269 $offset is the offset from the start of the file - it generally must 1671 $offset is the offset from the start of the file - it generally must
1270 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1672 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1292 IO::AIO::munlockall 1694 IO::AIO::munlockall
1293 Calls the "munlockall" function. 1695 Calls the "munlockall" function.
1294 1696
1295 On systems that do not implement "munlockall", this function returns 1697 On systems that do not implement "munlockall", this function returns
1296 ENOSYS, otherwise the return value of "munlockall". 1698 ENOSYS, otherwise the return value of "munlockall".
1699
1700 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1701 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1702 $w_off are "undef", then "NULL" is passed for these, otherwise they
1703 should be the file offset.
1704
1705 $r_fh and $w_fh should not refer to the same file, as splice might
1706 silently corrupt the data in this case.
1707
1708 The following symbol flag values are available:
1709 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1710 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1711
1712 See the splice(2) manpage for details.
1713
1714 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1715 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1716 description for "IO::AIO::splice" above for details.
1717
1718 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1719 Attempts to query or change the pipe buffer size. Obviously works
1720 only on pipes, and currently works only on GNU/Linux systems, and
1721 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1722 influence pipe buffer size on other systems, drop me a note.
1723
1724 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1725 This is a direct interface to the Linux pipe2(2) system call. If
1726 $flags is missing or 0, then this should be the same as a call to
1727 perl's built-in "pipe" function and create a new pipe, and works on
1728 systems that lack the pipe2 syscall. On win32, this case invokes
1729 "_pipe (..., 4096, O_BINARY)".
1730
1731 If $flags is non-zero, it tries to invoke the pipe2 system call with
1732 the given flags (Linux 2.6.27, glibc 2.9).
1733
1734 On success, the read and write file handles are returned.
1735
1736 On error, nothing will be returned. If the pipe2 syscall is missing
1737 and $flags is non-zero, fails with "ENOSYS".
1738
1739 Please refer to pipe2(2) for more info on the $flags, but at the
1740 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1741 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1742 supported.
1297 1743
1298EVENT LOOP INTEGRATION 1744EVENT LOOP INTEGRATION
1299 It is recommended to use AnyEvent::AIO to integrate IO::AIO 1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1300 automatically into many event loops: 1746 automatically into many event loops:
1301 1747
1324 # Danga::Socket integration 1770 # Danga::Socket integration
1325 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 1771 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1326 \&IO::AIO::poll_cb); 1772 \&IO::AIO::poll_cb);
1327 1773
1328 FORK BEHAVIOUR 1774 FORK BEHAVIOUR
1329 This module should do "the right thing" when the process using it forks: 1775 Usage of pthreads in a program changes the semantics of fork
1776 considerably. Specifically, only async-safe functions can be called
1777 after fork. Perl doesn't know about this, so in general, you cannot call
1778 fork with defined behaviour in perl if pthreads are involved. IO::AIO
1779 uses pthreads, so this applies, but many other extensions and (for
1780 inexplicable reasons) perl itself often is linked against pthreads, so
1781 this limitation applies to quite a lot of perls.
1330 1782
1331 Before the fork, IO::AIO enters a quiescent state where no requests can 1783 This module no longer tries to fight your OS, or POSIX. That means
1332 be added in other threads and no results will be processed. After the 1784 IO::AIO only works in the process that loaded it. Forking is fully
1333 fork the parent simply leaves the quiescent state and continues 1785 supported, but using IO::AIO in the child is not.
1334 request/result processing, while the child frees the request/result
1335 queue (so that the requests started before the fork will only be handled
1336 in the parent). Threads will be started on demand until the limit set in
1337 the parent process has been reached again.
1338 1786
1339 In short: the parent will, after a short pause, continue as if fork had 1787 You might get around by not *using* IO::AIO before (or after) forking.
1340 not been called, while the child will act as if IO::AIO has not been 1788 You could also try to call the IO::AIO::reinit function in the child:
1341 used yet. 1789
1790 IO::AIO::reinit
1791 Abandons all current requests and I/O threads and simply
1792 reinitialises all data structures. This is not an operation
1793 supported by any standards, but happens to work on GNU/Linux and
1794 some newer BSD systems.
1795
1796 The only reasonable use for this function is to call it after
1797 forking, if "IO::AIO" was used in the parent. Calling it while
1798 IO::AIO is active in the process will result in undefined behaviour.
1799 Calling it at any time will also result in any undefined (by POSIX)
1800 behaviour.
1342 1801
1343 MEMORY USAGE 1802 MEMORY USAGE
1344 Per-request usage: 1803 Per-request usage:
1345 1804
1346 Each aio request uses - depending on your architecture - around 100-200 1805 Each aio request uses - depending on your architecture - around 100-200

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