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Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC

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2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous Input/Output
3 3
4SYNOPSIS 4SYNOPSIS
5 use IO::AIO; 5 use IO::AIO;
6 6
7 aio_open "/etc/passwd", O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8 my $fh = shift 8 my $fh = shift
9 or die "/etc/passwd: $!"; 9 or die "/etc/passwd: $!";
10 ... 10 ...
11 }; 11 };
12 12
… …
23 my $req = aio_unlink "/tmp/file", sub { }; 23 my $req = aio_unlink "/tmp/file", sub { };
24 $req->cancel; # cancel request if still in queue 24 $req->cancel; # cancel request if still in queue
25 25
26 my $grp = aio_group sub { print "all stats done\n" }; 26 my $grp = aio_group sub { print "all stats done\n" };
27 add $grp aio_stat "..." for ...; 27 add $grp aio_stat "..." for ...;
28
29 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30 use AnyEvent::AIO;
31
32 # EV integration
33 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35 # Event integration
36 Event->io (fd => IO::AIO::poll_fileno,
37 poll => 'r',
38 cb => \&IO::AIO::poll_cb);
39
40 # Glib/Gtk2 integration
41 add_watch Glib::IO IO::AIO::poll_fileno,
42 in => sub { IO::AIO::poll_cb; 1 };
43
44 # Tk integration
45 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46 readable => \&IO::AIO::poll_cb);
47
48 # Danga::Socket integration
49 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50 \&IO::AIO::poll_cb);
51 28
52DESCRIPTION 29DESCRIPTION
53 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
54 operating system supports. It is implemented as an interface to "libeio" 31 operating system supports. It is implemented as an interface to "libeio"
55 (<http://software.schmorp.de/pkg/libeio.html>). 32 (<http://software.schmorp.de/pkg/libeio.html>).
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87 64
88 EXAMPLE 65 EXAMPLE
89 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
90 asynchronously: 67 asynchronously:
91 68
92 use Fcntl;
93 use EV; 69 use EV;
94 use IO::AIO; 70 use IO::AIO;
95 71
96 # register the IO::AIO callback with EV 72 # register the IO::AIO callback with EV
97 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;
98 74
99 # queue the request to open /etc/passwd 75 # queue the request to open /etc/passwd
100 aio_open "/etc/passwd", O_RDONLY, 0, sub { 76 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101 my $fh = shift 77 my $fh = shift
102 or die "error while opening: $!"; 78 or die "error while opening: $!";
103 79
104 # stat'ing filehandles is generally non-blocking 80 # stat'ing filehandles is generally non-blocking
105 my $size = -s $fh; 81 my $size = -s $fh;
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114 90
115 # file contents now in $contents 91 # file contents now in $contents
116 print $contents; 92 print $contents;
117 93
118 # exit event loop and program 94 # exit event loop and program
119 EV::unloop; 95 EV::break;
120 }; 96 };
121 }; 97 };
122 98
123 # possibly queue up other requests, or open GUI windows, 99 # possibly queue up other requests, or open GUI windows,
124 # check for sockets etc. etc. 100 # check for sockets etc. etc.
125 101
126 # process events as long as there are some: 102 # process events as long as there are some:
127 EV::loop; 103 EV::run;
128 104
129REQUEST ANATOMY AND LIFETIME 105REQUEST ANATOMY AND LIFETIME
130 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
131 not directly visible to Perl. 107 not directly visible to Perl.
132 108
… …
168 anymore (except possibly for the Perl object, but its connection to 144 anymore (except possibly for the Perl object, but its connection to
169 the actual aio request is severed and calling its methods will 145 the actual aio request is severed and calling its methods will
170 either do nothing or result in a runtime error). 146 either do nothing or result in a runtime error).
171 147
172FUNCTIONS 148FUNCTIONS
173 AIO REQUEST FUNCTIONS 149 QUICK OVERVIEW
150 This section simply lists the prototypes most of the functions for quick
151 reference. See the following sections for function-by-function
152 documentation.
153
154 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status)
157 aio_seek $fh,$offset,$whence, $callback->($offs)
158 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
160 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
161 aio_readahead $fh,$offset,$length, $callback->($retval)
162 aio_stat $fh_or_path, $callback->($status)
163 aio_lstat $fh, $callback->($status)
164 aio_statvfs $fh_or_path, $callback->($statvfs)
165 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
166 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
168 aio_truncate $fh_or_path, $offset, $callback->($status)
169 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
170 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
171 aio_unlink $pathname, $callback->($status)
172 aio_mknod $pathname, $mode, $dev, $callback->($status)
173 aio_link $srcpath, $dstpath, $callback->($status)
174 aio_symlink $srcpath, $dstpath, $callback->($status)
175 aio_readlink $pathname, $callback->($link)
176 aio_realpath $pathname, $callback->($path)
177 aio_rename $srcpath, $dstpath, $callback->($status)
178 aio_mkdir $pathname, $mode, $callback->($status)
179 aio_rmdir $pathname, $callback->($status)
180 aio_readdir $pathname, $callback->($entries)
181 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
182 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
183 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
184 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
185 aio_load $pathname, $data, $callback->($status)
186 aio_copy $srcpath, $dstpath, $callback->($status)
187 aio_move $srcpath, $dstpath, $callback->($status)
188 aio_rmtree $pathname, $callback->($status)
189 aio_fcntl $fh, $cmd, $arg, $callback->($status)
190 aio_ioctl $fh, $request, $buf, $callback->($status)
191 aio_sync $callback->($status)
192 aio_syncfs $fh, $callback->($status)
193 aio_fsync $fh, $callback->($status)
194 aio_fdatasync $fh, $callback->($status)
195 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
196 aio_pathsync $pathname, $callback->($status)
197 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
198 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
199 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
200 aio_mlockall $flags, $callback->($status)
201 aio_group $callback->(...)
202 aio_nop $callback->()
203
204 $prev_pri = aioreq_pri [$pri]
205 aioreq_nice $pri_adjust
206
207 IO::AIO::poll_wait
208 IO::AIO::poll_cb
209 IO::AIO::poll
210 IO::AIO::flush
211 IO::AIO::max_poll_reqs $nreqs
212 IO::AIO::max_poll_time $seconds
213 IO::AIO::min_parallel $nthreads
214 IO::AIO::max_parallel $nthreads
215 IO::AIO::max_idle $nthreads
216 IO::AIO::idle_timeout $seconds
217 IO::AIO::max_outstanding $maxreqs
218 IO::AIO::nreqs
219 IO::AIO::nready
220 IO::AIO::npending
221
222 IO::AIO::sendfile $ofh, $ifh, $offset, $count
223 IO::AIO::fadvise $fh, $offset, $len, $advice
224 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
225 IO::AIO::munmap $scalar
226 IO::AIO::madvise $scalar, $offset, $length, $advice
227 IO::AIO::mprotect $scalar, $offset, $length, $protect
228 IO::AIO::munlock $scalar, $offset = 0, $length = undef
229 IO::AIO::munlockall
230
231 API NOTES
174 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
175 with the same name (sans "aio_"). The arguments are similar or 233 with the same name (sans "aio_"). The arguments are similar or
176 identical, and they all accept an additional (and optional) $callback 234 identical, and they all accept an additional (and optional) $callback
177 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
178 called with the syscall return code (e.g. most syscalls return -1 on
179 error, unlike perl, which usually delivers "false") as its sole argument
180 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".
181 244
182 All functions expecting a filehandle keep a copy of the filehandle 245 All functions expecting a filehandle keep a copy of the filehandle
183 internally until the request has finished. 246 internally until the request has finished.
184 247
185 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
186 further manipulation of those requests while they are in-flight. 249 further manipulation of those requests while they are in-flight.
187 250
188 The pathnames you pass to these routines *must* be absolute and encoded 251 The pathnames you pass to these routines *should* be absolute. The
189 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
190 being executed, the current working directory could have changed. 253 current working directory could have changed. Alternatively, you can
191 Alternatively, you can make sure that you never change the current 254 make sure that you never change the current working directory anywhere
192 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.
193 259
194 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
195 pass in filenames you got from outside (command line, readdir etc.) 261 pass in filenames you got from outside (command line, readdir etc.)
196 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
197 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)
198 the user environment, d) use Glib::filename_from_unicode on unicode 264 encoding in effect in the user environment, d) use
199 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
200 contents. 266 else to ensure your scalar has the correct contents.
201 267
202 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
203 handles correctly whether it is set or not. 269 handles correctly whether it is set or not.
204 270
271 AIO REQUEST FUNCTIONS
205 $prev_pri = aioreq_pri [$pri] 272 $prev_pri = aioreq_pri [$pri]
206 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
207 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.
208 275
209 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
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231 Similar to "aioreq_pri", but subtracts the given value from the 298 Similar to "aioreq_pri", but subtracts the given value from the
232 current priority, so the effect is cumulative. 299 current priority, so the effect is cumulative.
233 300
234 aio_open $pathname, $flags, $mode, $callback->($fh) 301 aio_open $pathname, $flags, $mode, $callback->($fh)
235 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
236 newly created filehandle for the file. 303 newly created filehandle for the file (or "undef" in case of an
304 error).
237 305
238 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,
239 above, for an explanation. 307 above, for an explanation.
240 308
241 The $flags argument is a bitmask. See the "Fcntl" module for a list. 309 The $flags argument is a bitmask. See the "Fcntl" module for a list.
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248 will be modified by the umask in effect then the request is being 316 will be modified by the umask in effect then the request is being
249 executed, so better never change the umask. 317 executed, so better never change the umask.
250 318
251 Example: 319 Example:
252 320
253 aio_open "/etc/passwd", O_RDONLY, 0, sub { 321 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254 if ($_[0]) { 322 if ($_[0]) {
255 print "open successful, fh is $_[0]\n"; 323 print "open successful, fh is $_[0]\n";
256 ... 324 ...
257 } else { 325 } else {
258 die "open failed: $!\n"; 326 die "open failed: $!\n";
259 } 327 }
260 }; 328 };
261 329
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
262 aio_close $fh, $callback->($status) 340 aio_close $fh, $callback->($status)
263 Asynchronously close a file and call the callback with the result 341 Asynchronously close a file and call the callback with the result
264 code. 342 code.
265 343
266 Unfortunately, you can't do this to perl. Perl *insists* very 344 Unfortunately, you can't do this to perl. Perl *insists* very
… …
271 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
272 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).
273 351
274 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
275 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".
276 373
277 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 374 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
278 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 375 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279 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
280 $offset into the scalar given by $data and offset $dataoffset and 377 $offset into the scalar given by $data and offset $dataoffset and
… …
309 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 406 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
310 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
311 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
312 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
313 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
314 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.
315 413
414 Please note that "aio_sendfile" can read more bytes from $in_fh than
415 are written, and there is no way to find out how many more bytes
416 have been read from "aio_sendfile" alone, as "aio_sendfile" only
417 provides the number of bytes written to $out_fh. Only if the result
418 value equals $length one can assume that $length bytes have been
419 read.
420
421 Unlike with other "aio_" functions, it makes a lot of sense to use
422 "aio_sendfile" on non-blocking sockets, as long as one end
423 (typically the $in_fh) is a file - the file I/O will then be
424 asynchronous, while the socket I/O will be non-blocking. Note,
425 however, that you can run into a trap where "aio_sendfile" reads
426 some data with readahead, then fails to write all data, and when the
427 socket is ready the next time, the data in the cache is already
428 lost, forcing "aio_sendfile" to again hit the disk. Explicit
429 "aio_read" + "aio_write" let's you better control resource usage.
430
316 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
317 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
318 to a socket, and $in_fh should refer to mmap'able file. 433 to a socket, and $in_fh should refer to an mmap'able file.
319 434
320 If the native sendfile call fails or is not implemented, it will be 435 If a native sendfile cannot be found or it fails with "ENOSYS",
321 emulated, so you can call "aio_sendfile" on any type of filehandle 436 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322 regardless of the limitations of the operating system. 437 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
438 any type of filehandle regardless of the limitations of the
439 operating system.
323 440
324 Please note, however, that "aio_sendfile" can read more bytes from 441 As native sendfile syscalls (as practically any non-POSIX interface
325 $in_fh than are written, and there is no way to find out how many 442 hacked together in a hurry to improve benchmark numbers) tend to be
326 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 443 rather buggy on many systems, this implementation tries to work
327 only provides the number of bytes written to $out_fh. Only if the 444 around some known bugs in Linux and FreeBSD kernels (probably
328 result value equals $length one can assume that $length bytes have 445 others, too), but that might fail, so you really really should check
329 been read. 446 the return value of "aio_sendfile" - fewre bytes than expected might
447 have been transferred.
330 448
331 aio_readahead $fh,$offset,$length, $callback->($retval) 449 aio_readahead $fh,$offset,$length, $callback->($retval)
332 "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
333 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
334 $offset argument specifies the starting point from which data is to 452 $offset argument specifies the starting point from which data is to
… …
355 Currently, the stats are always 64-bit-stats, i.e. instead of 473 Currently, the stats are always 64-bit-stats, i.e. instead of
356 returning an error when stat'ing a large file, the results will be 474 returning an error when stat'ing a large file, the results will be
357 silently truncated unless perl itself is compiled with large file 475 silently truncated unless perl itself is compiled with large file
358 support. 476 support.
359 477
478 To help interpret the mode and dev/rdev stat values, IO::AIO offers
479 the following constants and functions (if not implemented, the
480 constants will be 0 and the functions will either "croak" or fall
481 back on traditional behaviour).
482
483 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
484 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
485 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
486
360 Example: Print the length of /etc/passwd: 487 Example: Print the length of /etc/passwd:
361 488
362 aio_stat "/etc/passwd", sub { 489 aio_stat "/etc/passwd", sub {
363 $_[0] and die "stat failed: $!"; 490 $_[0] and die "stat failed: $!";
364 print "size is ", -s _, "\n"; 491 print "size is ", -s _, "\n";
365 }; 492 };
366 493
494 aio_statvfs $fh_or_path, $callback->($statvfs)
495 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
496 whether a file handle or path was passed.
497
498 On success, the callback is passed a hash reference with the
499 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
500 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
501 failure, "undef" is passed.
502
503 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
504 and "ST_NOSUID".
505
506 The following non-POSIX IO::AIO::ST_* flag masks are defined to
507 their correct value when available, or to 0 on systems that do not
508 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
509 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
510 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
511
512 Example: stat "/wd" and dump out the data if successful.
513
514 aio_statvfs "/wd", sub {
515 my $f = $_[0]
516 or die "statvfs: $!";
517
518 use Data::Dumper;
519 say Dumper $f;
520 };
521
522 # result:
523 {
524 bsize => 1024,
525 bfree => 4333064312,
526 blocks => 10253828096,
527 files => 2050765568,
528 flag => 4096,
529 favail => 2042092649,
530 bavail => 4333064312,
531 ffree => 2042092649,
532 namemax => 255,
533 frsize => 1024,
534 fsid => 1810
535 }
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
367 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 622 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368 Works like perl's "utime" function (including the special case of 623 Works like perl's "utime" function (including the special case of
369 $atime and $mtime being undef). Fractional times are supported if 624 $atime and $mtime being undef). Fractional times are supported if
370 the underlying syscalls support them. 625 the underlying syscalls support them.
371 626
… …
393 aio_chown "path", 0, undef; 648 aio_chown "path", 0, undef;
394 649
395 aio_truncate $fh_or_path, $offset, $callback->($status) 650 aio_truncate $fh_or_path, $offset, $callback->($status)
396 Works like truncate(2) or ftruncate(2). 651 Works like truncate(2) or ftruncate(2).
397 652
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
398 aio_chmod $fh_or_path, $mode, $callback->($status) 671 aio_chmod $fh_or_path, $mode, $callback->($status)
399 Works like perl's "chmod" function. 672 Works like perl's "chmod" function.
400 673
401 aio_unlink $pathname, $callback->($status) 674 aio_unlink $pathname, $callback->($status)
402 Asynchronously unlink (delete) a file and call the callback with the 675 Asynchronously unlink (delete) a file and call the callback with the
403 result code. 676 result code.
404 677
405 aio_mknod $path, $mode, $dev, $callback->($status) 678 aio_mknod $pathname, $mode, $dev, $callback->($status)
406 [EXPERIMENTAL] 679 [EXPERIMENTAL]
407 680
408 Asynchronously create a device node (or fifo). See mknod(2). 681 Asynchronously create a device node (or fifo). See mknod(2).
409 682
410 The only (POSIX-) portable way of calling this function is: 683 The only (POSIX-) portable way of calling this function is:
411 684
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 685 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
686
687 See "aio_stat" for info about some potentially helpful extra
688 constants and functions.
413 689
414 aio_link $srcpath, $dstpath, $callback->($status) 690 aio_link $srcpath, $dstpath, $callback->($status)
415 Asynchronously create a new link to the existing object at $srcpath 691 Asynchronously create a new link to the existing object at $srcpath
416 at the path $dstpath and call the callback with the result code. 692 at the path $dstpath and call the callback with the result code.
417 693
418 aio_symlink $srcpath, $dstpath, $callback->($status) 694 aio_symlink $srcpath, $dstpath, $callback->($status)
419 Asynchronously create a new symbolic link to the existing object at 695 Asynchronously create a new symbolic link to the existing object at
420 $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
421 code. 697 code.
422 698
423 aio_readlink $path, $callback->($link) 699 aio_readlink $pathname, $callback->($link)
424 Asynchronously read the symlink specified by $path and pass it to 700 Asynchronously read the symlink specified by $path and pass it to
425 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
426 the callback. 702 the callback.
427 703
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
428 aio_rename $srcpath, $dstpath, $callback->($status) 712 aio_rename $srcpath, $dstpath, $callback->($status)
429 Asynchronously rename the object at $srcpath to $dstpath, just as 713 Asynchronously rename the object at $srcpath to $dstpath, just as
430 rename(2) and call the callback with the result code. 714 rename(2) and call the callback with the result code.
715
716 On systems that support the AIO::WD working directory abstraction
717 natively, the case "[$wd, "."]" as $srcpath is specialcased -
718 instead of failing, "rename" is called on the absolute path of $wd.
431 719
432 aio_mkdir $pathname, $mode, $callback->($status) 720 aio_mkdir $pathname, $mode, $callback->($status)
433 Asynchronously mkdir (create) a directory and call the callback with 721 Asynchronously mkdir (create) a directory and call the callback with
434 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
435 request is executed, so do not change your umask. 723 request is executed, so do not change your umask.
436 724
437 aio_rmdir $pathname, $callback->($status) 725 aio_rmdir $pathname, $callback->($status)
438 Asynchronously rmdir (delete) a directory and call the callback with 726 Asynchronously rmdir (delete) a directory and call the callback with
439 the result code. 727 the result code.
440 728
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
441 aio_readdir $pathname, $callback->($entries) 733 aio_readdir $pathname, $callback->($entries)
442 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
443 entire directory (i.e. opendir + readdir + closedir). The entries 735 entire directory (i.e. opendir + readdir + closedir). The entries
444 will not be sorted, and will NOT include the "." and ".." entries. 736 will not be sorted, and will NOT include the "." and ".." entries.
445 737
446 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
447 an array-ref with the filenames. 739 an array-ref with the filenames.
448 740
449 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 741 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
450 Quite similar to "aio_readdir", but the $flags argument allows to 742 Quite similar to "aio_readdir", but the $flags argument allows one
451 tune behaviour and output format. In case of an error, $entries will 743 to tune behaviour and output format. In case of an error, $entries
452 be "undef". 744 will be "undef".
453 745
454 The flags are a combination of the following constants, ORed 746 The flags are a combination of the following constants, ORed
455 together (the flags will also be passed to the callback, possibly 747 together (the flags will also be passed to the callback, possibly
456 modified): 748 modified):
457 749
458 IO::AIO::READDIR_DENTS 750 IO::AIO::READDIR_DENTS
459 When this flag is off, then the callback gets an arrayref with 751 When this flag is off, then the callback gets an arrayref
460 of names only (as with "aio_readdir"), otherwise it gets an 752 consisting of names only (as with "aio_readdir"), otherwise it
461 arrayref with "[$name, $type, $inode]" arrayrefs, each 753 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462 describing a single directory entry in more detail. 754 describing a single directory entry in more detail.
463 755
464 $name is the name of the entry. 756 $name is the name of the entry.
465 757
466 $type is one of the "IO::AIO::DT_xxx" constants: 758 $type is one of the "IO::AIO::DT_xxx" constants:
… …
479 unspecified content on systems that do not deliver the inode 771 unspecified content on systems that do not deliver the inode
480 information. 772 information.
481 773
482 IO::AIO::READDIR_DIRS_FIRST 774 IO::AIO::READDIR_DIRS_FIRST
483 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
484 order where likely directories come first. This is useful when 776 order where likely directories come first, in optimal stat
485 you need to quickly find directories, or you want to find all 777 order. This is useful when you need to quickly find directories,
486 directories while avoiding to stat() each entry. 778 or you want to find all directories while avoiding to stat()
779 each entry.
487 780
488 If the system returns type information in readdir, then this is 781 If the system returns type information in readdir, then this is
489 used to find directories directly. Otherwise, likely directories 782 used to find directories directly. Otherwise, likely directories
490 are files beginning with ".", or otherwise files with no dots, 783 are names beginning with ".", or otherwise names with no dots,
491 of which files with short names are tried first. 784 of which names with short names are tried first.
492 785
493 IO::AIO::READDIR_STAT_ORDER 786 IO::AIO::READDIR_STAT_ORDER
494 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
495 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
496 to stat() all files in the given directory, then the returned 789 to stat() all files in the given directory, then the returned
… …
501 optimal stat order. 794 optimal stat order.
502 795
503 IO::AIO::READDIR_FOUND_UNKNOWN 796 IO::AIO::READDIR_FOUND_UNKNOWN
504 This flag should not be set when calling "aio_readdirx". 797 This flag should not be set when calling "aio_readdirx".
505 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
506 $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
507 flag therefore indicates that all $type's are known, which can 800 flag therefore indicates that all $type's are known, which can
508 be used to speed up some algorithms. 801 be used to speed up some algorithms.
509 802
510 aio_load $path, $data, $callback->($status) 803 aio_load $pathname, $data, $callback->($status)
511 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
512 into memory. Status is the same as with aio_read. 805 into memory. Status is the same as with aio_read.
513 806
514 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
515 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
516 or destination) from $srcpath to $dstpath and call the callback with 809 or destination) from $srcpath to $dstpath and call the callback with
517 the 0 (error) or -1 ok. 810 a status of 0 (ok) or -1 (error, see $!).
518 811
519 This is a composite request that creates the destination file with 812 This is a composite request that creates the destination file with
520 mode 0200 and copies the contents of the source file into it using 813 mode 0200 and copies the contents of the source file into it using
521 "aio_sendfile", followed by restoring atime, mtime, access mode and 814 "aio_sendfile", followed by restoring atime, mtime, access mode and
522 uid/gid, in that order. 815 uid/gid, in that order.
… …
526 uid/gid, where errors are being ignored. 819 uid/gid, where errors are being ignored.
527 820
528 aio_move $srcpath, $dstpath, $callback->($status) 821 aio_move $srcpath, $dstpath, $callback->($status)
529 Try to move the *file* (directories not supported as either source 822 Try to move the *file* (directories not supported as either source
530 or destination) from $srcpath to $dstpath and call the callback with 823 or destination) from $srcpath to $dstpath and call the callback with
531 the 0 (error) or -1 ok. 824 a status of 0 (ok) or -1 (error, see $!).
532 825
533 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;
534 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"
535 and, if that is successful, unlinks the $srcpath. 828 and, if that is successful, unlinks the $srcpath.
536 829
537 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 830 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
538 Scans a directory (similar to "aio_readdir") but additionally tries 831 Scans a directory (similar to "aio_readdir") but additionally tries
539 to efficiently separate the entries of directory $path into two sets 832 to efficiently separate the entries of directory $path into two sets
540 of names, directories you can recurse into (directories), and ones 833 of names, directories you can recurse into (directories), and ones
541 you cannot recurse into (everything else, including symlinks to 834 you cannot recurse into (everything else, including symlinks to
542 directories). 835 directories).
… …
575 Then entries will be sorted into likely directories a non-initial 868 Then entries will be sorted into likely directories a non-initial
576 dot currently) and likely non-directories (see "aio_readdirx"). Then 869 dot currently) and likely non-directories (see "aio_readdirx"). Then
577 every entry plus an appended "/." will be "stat"'ed, likely 870 every entry plus an appended "/." will be "stat"'ed, likely
578 directories first, in order of their inode numbers. If that 871 directories first, in order of their inode numbers. If that
579 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
580 directory (which will be checked seperately). This is often faster 873 directory (which will be checked separately). This is often faster
581 than stat'ing the entry itself because filesystems might detect the 874 than stat'ing the entry itself because filesystems might detect the
582 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
583 filetype feature), even on systems that cannot return the filetype 876 filetype feature), even on systems that cannot return the filetype
584 information on readdir. 877 information on readdir.
585 878
… …
591 884
592 It will also likely work on non-POSIX filesystems with reduced 885 It will also likely work on non-POSIX filesystems with reduced
593 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
594 disables the directory counting heuristic. 887 disables the directory counting heuristic.
595 888
596 aio_rmtree $path, $callback->($status) 889 aio_rmtree $pathname, $callback->($status)
597 Delete a directory tree starting (and including) $path, return the 890 Delete a directory tree starting (and including) $path, return the
598 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
599 uses "aio_scandir" to recurse into and rmdir directories, and unlink 892 uses "aio_scandir" to recurse into and rmdir directories, and unlink
600 everything else. 893 everything else.
601 894
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
602 aio_sync $callback->($status) 913 aio_sync $callback->($status)
603 Asynchronously call sync and call the callback when finished. 914 Asynchronously call sync and call the callback when finished.
604 915
605 aio_fsync $fh, $callback->($status) 916 aio_fsync $fh, $callback->($status)
606 Asynchronously call fsync on the given filehandle and call the 917 Asynchronously call fsync on the given filehandle and call the
… …
610 Asynchronously call fdatasync on the given filehandle and call the 921 Asynchronously call fdatasync on the given filehandle and call the
611 callback with the fdatasync result code. 922 callback with the fdatasync result code.
612 923
613 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
614 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.
615 932
616 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 933 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
617 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
618 to disk (but NOT the metadata), by calling the Linux-specific 935 to disk (but NOT the metadata), by calling the Linux-specific
619 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
… …
623 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 940 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
624 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 941 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
625 "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
626 manpage for details. 943 manpage for details.
627 944
628 aio_pathsync $path, $callback->($status) 945 aio_pathsync $pathname, $callback->($status)
629 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
630 a composite request intended to sync directories after directory 947 a composite request intended to sync directories after directory
631 operations (E.g. rename). This might not work on all operating 948 operations (E.g. rename). This might not work on all operating
632 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
633 directory changes get written to disc. It works for anything that 950 directory changes get written to disc. It works for anything that
… …
636 Future versions of this function might fall back to other methods 953 Future versions of this function might fall back to other methods
637 when "fsync" on the directory fails (such as calling "sync"). 954 when "fsync" on the directory fails (such as calling "sync").
638 955
639 Passes 0 when everything went ok, and -1 on error. 956 Passes 0 when everything went ok, and -1 on error.
640 957
958 aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
959 $callback->($status)
960 This is a rather advanced IO::AIO call, which only works on
961 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
962 also works on data scalars managed by the Sys::Mmap or Mmap modules,
963 note that the scalar must only be modified in-place while an aio
964 operation is pending on it).
965
966 It calls the "msync" function of your OS, if available, with the
967 memory area starting at $offset in the string and ending $length
968 bytes later. If $length is negative, counts from the end, and if
969 $length is "undef", then it goes till the end of the string. The
970 flags can be a combination of "IO::AIO::MS_ASYNC",
971 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
972
973 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
974 $callback->($status)
975 This is a rather advanced IO::AIO call, which works best on
976 mmap(2)ed scalars.
977
978 It touches (reads or writes) all memory pages in the specified range
979 inside the scalar. All caveats and parameters are the same as for
980 "aio_msync", above, except for flags, which must be either 0 (which
981 reads all pages and ensures they are instantiated) or
982 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
983 and writing an octet from it, which dirties the page).
984
985 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
986 This is a rather advanced IO::AIO call, which works best on
987 mmap(2)ed scalars.
988
989 It reads in all the pages of the underlying storage into memory (if
990 any) and locks them, so they are not getting swapped/paged out or
991 removed.
992
993 If $length is undefined, then the scalar will be locked till the
994 end.
995
996 On systems that do not implement "mlock", this function returns -1
997 and sets errno to "ENOSYS".
998
999 Note that the corresponding "munlock" is synchronous and is
1000 documented under "MISCELLANEOUS FUNCTIONS".
1001
1002 Example: open a file, mmap and mlock it - both will be undone when
1003 $data gets destroyed.
1004
1005 open my $fh, "<", $path or die "$path: $!";
1006 my $data;
1007 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1008 aio_mlock $data; # mlock in background
1009
1010 aio_mlockall $flags, $callback->($status)
1011 Calls the "mlockall" function with the given $flags (a combination
1012 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
1013
1014 On systems that do not implement "mlockall", this function returns
1015 -1 and sets errno to "ENOSYS".
1016
1017 Note that the corresponding "munlockall" is synchronous and is
1018 documented under "MISCELLANEOUS FUNCTIONS".
1019
1020 Example: asynchronously lock all current and future pages into
1021 memory.
1022
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.
1072
641 aio_group $callback->(...) 1073 aio_group $callback->(...)
642 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
643 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
644 to bundle many requests into a single, composite, request with a 1076 to bundle many requests into a single, composite, request with a
645 definite callback and the ability to cancel the whole request with 1077 definite callback and the ability to cancel the whole request with
… …
678 While it is theoretically handy to have simple I/O scheduling 1110 While it is theoretically handy to have simple I/O scheduling
679 requests like sleep and file handle readable/writable, the overhead 1111 requests like sleep and file handle readable/writable, the overhead
680 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
681 not use this function except to put your application under 1113 not use this function except to put your application under
682 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.
683 1233
684 IO::AIO::REQ CLASS 1234 IO::AIO::REQ CLASS
685 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
686 called in non-void context. 1236 called in non-void context.
687 1237
… …
761 $grp->cancel_subs 1311 $grp->cancel_subs
762 Cancel all subrequests and clears any feeder, but not the group 1312 Cancel all subrequests and clears any feeder, but not the group
763 request itself. Useful when you queued a lot of events but got a 1313 request itself. Useful when you queued a lot of events but got a
764 result early. 1314 result early.
765 1315
1316 The group request will finish normally (you cannot add requests to
1317 the group).
1318
766 $grp->result (...) 1319 $grp->result (...)
767 Set the result value(s) that will be passed to the group callback 1320 Set the result value(s) that will be passed to the group callback
768 when all subrequests have finished and set the groups errno to the 1321 when all subrequests have finished and set the groups errno to the
769 current value of errno (just like calling "errno" without an error 1322 current value of errno (just like calling "errno" without an error
770 number). By default, no argument will be passed and errno is zero. 1323 number). By default, no argument will be passed and errno is zero.
… …
784 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
785 attached generator that generates requests if idle. The idea behind 1338 attached generator that generates requests if idle. The idea behind
786 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
787 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
788 long time. For example, "aio_scandir" might generate hundreds of 1341 long time. For example, "aio_scandir" might generate hundreds of
789 thousands "aio_stat" requests, delaying any later requests for a 1342 thousands of "aio_stat" requests, delaying any later requests for a
790 long time. 1343 long time.
791 1344
792 To avoid this, and allow incremental generation of requests, you can 1345 To avoid this, and allow incremental generation of requests, you can
793 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
794 requests. The feed callback will be called whenever there are few 1347 requests. The feed callback will be called whenever there are few
… …
836 results. 1389 results.
837 1390
838 See "poll_cb" for an example. 1391 See "poll_cb" for an example.
839 1392
840 IO::AIO::poll_cb 1393 IO::AIO::poll_cb
841 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
842 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
843 it returned earlier for whatever reason. Returns immediately when no 1396 to call this "regularly" to finish outstanding requests.
844 events are outstanding. The amount of events processed depends on
845 the settings of "IO::AIO::max_poll_req" and
846 "IO::AIO::max_poll_time".
847 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
848 If not all requests were processed for whatever reason, the 1404 If not all requests were processed for whatever reason, the poll
849 filehandle will still be ready when "poll_cb" returns, so normally 1405 file descriptor will still be ready when "poll_cb" returns, so
850 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.
851 1415
852 Example: Install an Event watcher that automatically calls 1416 Example: Install an Event watcher that automatically calls
853 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
854 the SYNOPSIS section, at the top of this document): 1418 the SYNOPSIS section, at the top of this document):
855 1419
856 Event->io (fd => IO::AIO::poll_fileno, 1420 Event->io (fd => IO::AIO::poll_fileno,
857 poll => 'r', async => 1, 1421 poll => 'r', async => 1,
858 cb => \&IO::AIO::poll_cb); 1422 cb => \&IO::AIO::poll_cb);
1423
1424 IO::AIO::poll_wait
1425 Wait until either at least one request is in the result phase or no
1426 requests are outstanding anymore.
1427
1428 This is useful if you want to synchronously wait for some requests
1429 to become ready, without actually handling them.
1430
1431 See "nreqs" for an example.
1432
1433 IO::AIO::poll
1434 Waits until some requests have been handled.
1435
1436 Returns the number of requests processed, but is otherwise strictly
1437 equivalent to:
1438
1439 IO::AIO::poll_wait, IO::AIO::poll_cb
1440
1441 IO::AIO::flush
1442 Wait till all outstanding AIO requests have been handled.
1443
1444 Strictly equivalent to:
1445
1446 IO::AIO::poll_wait, IO::AIO::poll_cb
1447 while IO::AIO::nreqs;
859 1448
860 IO::AIO::max_poll_reqs $nreqs 1449 IO::AIO::max_poll_reqs $nreqs
861 IO::AIO::max_poll_time $seconds 1450 IO::AIO::max_poll_time $seconds
862 These set the maximum number of requests (default 0, meaning 1451 These set the maximum number of requests (default 0, meaning
863 infinity) that are being processed by "IO::AIO::poll_cb" in one 1452 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
887 # use a low priority so other tasks have priority 1476 # use a low priority so other tasks have priority
888 Event->io (fd => IO::AIO::poll_fileno, 1477 Event->io (fd => IO::AIO::poll_fileno,
889 poll => 'r', nice => 1, 1478 poll => 'r', nice => 1,
890 cb => &IO::AIO::poll_cb); 1479 cb => &IO::AIO::poll_cb);
891 1480
892 IO::AIO::poll_wait
893 If there are any outstanding requests and none of them in the result
894 phase, wait till the result filehandle becomes ready for reading
895 (simply does a "select" on the filehandle. This is useful if you
896 want to synchronously wait for some requests to finish).
897
898 See "nreqs" for an example.
899
900 IO::AIO::poll
901 Waits until some requests have been handled.
902
903 Returns the number of requests processed, but is otherwise strictly
904 equivalent to:
905
906 IO::AIO::poll_wait, IO::AIO::poll_cb
907
908 IO::AIO::flush
909 Wait till all outstanding AIO requests have been handled.
910
911 Strictly equivalent to:
912
913 IO::AIO::poll_wait, IO::AIO::poll_cb
914 while IO::AIO::nreqs;
915
916 CONTROLLING THE NUMBER OF THREADS 1481 CONTROLLING THE NUMBER OF THREADS
917 IO::AIO::min_parallel $nthreads 1482 IO::AIO::min_parallel $nthreads
918 Set the minimum number of AIO threads to $nthreads. The current 1483 Set the minimum number of AIO threads to $nthreads. The current
919 default is 8, which means eight asynchronous operations can execute 1484 default is 8, which means eight asynchronous operations can execute
920 concurrently at any one time (the number of outstanding requests, 1485 concurrently at any one time (the number of outstanding requests,
… …
949 1514
950 Under normal circumstances you don't need to call this function. 1515 Under normal circumstances you don't need to call this function.
951 1516
952 IO::AIO::max_idle $nthreads 1517 IO::AIO::max_idle $nthreads
953 Limit the number of threads (default: 4) that are allowed to idle 1518 Limit the number of threads (default: 4) that are allowed to idle
954 (i.e., threads that did not get a request to process within 10 1519 (i.e., threads that did not get a request to process within the idle
955 seconds). That means if a thread becomes idle while $nthreads other 1520 timeout (default: 10 seconds). That means if a thread becomes idle
956 threads are also idle, it will free its resources and exit. 1521 while $nthreads other threads are also idle, it will free its
1522 resources and exit.
957 1523
958 This is useful when you allow a large number of threads (e.g. 100 or 1524 This is useful when you allow a large number of threads (e.g. 100 or
959 1000) to allow for extremely high load situations, but want to free 1525 1000) to allow for extremely high load situations, but want to free
960 resources under normal circumstances (1000 threads can easily 1526 resources under normal circumstances (1000 threads can easily
961 consume 30MB of RAM). 1527 consume 30MB of RAM).
962 1528
963 The default is probably ok in most situations, especially if thread 1529 The default is probably ok in most situations, especially if thread
964 creation is fast. If thread creation is very slow on your system you 1530 creation is fast. If thread creation is very slow on your system you
965 might want to use larger values. 1531 might want to use larger values.
966 1532
1533 IO::AIO::idle_timeout $seconds
1534 Sets the minimum idle timeout (default 10) after which worker
1535 threads are allowed to exit. SEe "IO::AIO::max_idle".
1536
967 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
968 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
969 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
970 inexact: Better use an "aio_group" together with a feed callback. 1549 inexact: Better use an "aio_group" together with a feed callback.
971 1550
972 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
973 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:
974 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
975 function will block until the limit is no longer exceeded.
976 1553
977 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
978 the number of outstanding requests. 1570 no practical limit on the number of outstanding requests.
979
980 You can still queue as many requests as you want. Therefore,
981 "max_outstanding" is mainly useful in simple scripts (with low
982 values) or as a stop gap to shield against fatal memory overflow
983 (with large values).
984 1571
985 STATISTICAL INFORMATION 1572 STATISTICAL INFORMATION
986 IO::AIO::nreqs 1573 IO::AIO::nreqs
987 Returns the number of requests currently in the ready, execute or 1574 Returns the number of requests currently in the ready, execute or
988 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
… …
1000 IO::AIO::npending 1587 IO::AIO::npending
1001 Returns the number of requests currently in the pending state 1588 Returns the number of requests currently in the pending state
1002 (executed, but not yet processed by poll_cb). 1589 (executed, but not yet processed by poll_cb).
1003 1590
1004 MISCELLANEOUS FUNCTIONS 1591 MISCELLANEOUS FUNCTIONS
1005 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
1006 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.
1007 1596
1008 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1597 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1009 Calls the "eio_sendfile_sync" function, which is like 1598 Calls the "eio_sendfile_sync" function, which is like
1010 "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
1011 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
1012 set to non-blocking operations). 1601 set to non-blocking operations).
1013 1602
1014 Returns the number of bytes copied, or -1 on error. 1603 Returns the number of bytes copied, or -1 on error.
1015 1604
1016 IO::AIO::fadvise $fh, $offset, $len, $advice 1605 IO::AIO::fadvise $fh, $offset, $len, $advice
1017 Simply calls the "posix_fadvise" function (see it's manpage for 1606 Simply calls the "posix_fadvise" function (see its manpage for
1018 details). The following advice constants are avaiable: 1607 details). The following advice constants are available:
1019 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1608 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1609 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1610 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022 1611
1023 On systems that do not implement "posix_fadvise", this function 1612 On systems that do not implement "posix_fadvise", this function
1024 returns ENOSYS, otherwise the return value of "posix_fadvise". 1613 returns ENOSYS, otherwise the return value of "posix_fadvise".
1025 1614
1615 IO::AIO::madvise $scalar, $offset, $len, $advice
1616 Simply calls the "posix_madvise" function (see its manpage for
1617 details). The following advice constants are available:
1618 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1619 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1620 "IO::AIO::MADV_DONTNEED".
1621
1622 On systems that do not implement "posix_madvise", this function
1623 returns ENOSYS, otherwise the return value of "posix_madvise".
1624
1625 IO::AIO::mprotect $scalar, $offset, $len, $protect
1626 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1627 $scalar (see its manpage for details). The following protect
1628 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1629 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1630
1631 On systems that do not implement "mprotect", this function returns
1632 ENOSYS, otherwise the return value of "mprotect".
1633
1634 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1635 Memory-maps a file (or anonymous memory range) and attaches it to
1636 the given $scalar, which will act like a string scalar. Returns true
1637 on success, and false otherwise.
1638
1639 The only operations allowed on the scalar are "substr"/"vec" that
1640 don't change the string length, and most read-only operations such
1641 as copying it or searching it with regexes and so on.
1642
1643 Anything else is unsafe and will, at best, result in memory leaks.
1644
1645 The memory map associated with the $scalar is automatically removed
1646 when the $scalar is destroyed, or when the "IO::AIO::mmap" or
1647 "IO::AIO::munmap" functions are called.
1648
1649 This calls the "mmap"(2) function internally. See your system's
1650 manual page for details on the $length, $prot and $flags parameters.
1651
1652 The $length must be larger than zero and smaller than the actual
1653 filesize.
1654
1655 $prot is a combination of "IO::AIO::PROT_NONE",
1656 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1657 "IO::AIO::PROT_WRITE",
1658
1659 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1660 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1661 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1662 "MAP_ANON" if your system only provides this constant),
1663 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1664 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1665 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1666 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1667 "IO::AIO::MAP_STACK".
1668
1669 If $fh is "undef", then a file descriptor of -1 is passed.
1670
1671 $offset is the offset from the start of the file - it generally must
1672 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1673
1674 Example:
1675
1676 use Digest::MD5;
1677 use IO::AIO;
1678
1679 open my $fh, "<verybigfile"
1680 or die "$!";
1681
1682 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1683 or die "verybigfile: $!";
1684
1685 my $fast_md5 = md5 $data;
1686
1687 IO::AIO::munmap $scalar
1688 Removes a previous mmap and undefines the $scalar.
1689
1690 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1691 Calls the "munlock" function, undoing the effects of a previous
1692 "aio_mlock" call (see its description for details).
1693
1694 IO::AIO::munlockall
1695 Calls the "munlockall" function.
1696
1697 On systems that do not implement "munlockall", this function returns
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.
1743
1744EVENT LOOP INTEGRATION
1745 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1746 automatically into many event loops:
1747
1748 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1749 use AnyEvent::AIO;
1750
1751 You can also integrate IO::AIO manually into many event loops, here are
1752 some examples of how to do this:
1753
1754 # EV integration
1755 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1756
1757 # Event integration
1758 Event->io (fd => IO::AIO::poll_fileno,
1759 poll => 'r',
1760 cb => \&IO::AIO::poll_cb);
1761
1762 # Glib/Gtk2 integration
1763 add_watch Glib::IO IO::AIO::poll_fileno,
1764 in => sub { IO::AIO::poll_cb; 1 };
1765
1766 # Tk integration
1767 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1768 readable => \&IO::AIO::poll_cb);
1769
1770 # Danga::Socket integration
1771 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1772 \&IO::AIO::poll_cb);
1773
1026 FORK BEHAVIOUR 1774 FORK BEHAVIOUR
1027 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.
1028 1782
1029 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
1030 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
1031 fork the parent simply leaves the quiescent state and continues 1785 supported, but using IO::AIO in the child is not.
1032 request/result processing, while the child frees the request/result
1033 queue (so that the requests started before the fork will only be handled
1034 in the parent). Threads will be started on demand until the limit set in
1035 the parent process has been reached again.
1036 1786
1037 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.
1038 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:
1039 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.
1040 1801
1041 MEMORY USAGE 1802 MEMORY USAGE
1042 Per-request usage: 1803 Per-request usage:
1043 1804
1044 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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