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1NAME 1NAME
2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous/Advanced 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>).
… …
78 not well-supported or restricted (GNU/Linux doesn't allow them on normal 55 not well-supported or restricted (GNU/Linux doesn't allow them on normal
79 files currently, for example), and they would only support aio_read and 56 files currently, for example), and they would only support aio_read and
80 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
81 using threads anyway. 58 using threads anyway.
82 59
60 In addition to asynchronous I/O, this module also exports some rather
61 arcane interfaces, such as "madvise" or linux's "splice" system call,
62 which is why the "A" in "AIO" can also mean *advanced*.
63
83 Although the module will work in the presence of other (Perl-) threads, 64 Although the module will work in the presence of other (Perl-) threads,
84 it is currently not reentrant in any way, so use appropriate locking 65 it is currently not reentrant in any way, so use appropriate locking
85 yourself, always call "poll_cb" from within the same thread, or never 66 yourself, always call "poll_cb" from within the same thread, or never
86 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
87 68
88 EXAMPLE 69 EXAMPLE
89 This is a simple example that uses the EV module and loads /etc/passwd 70 This is a simple example that uses the EV module and loads /etc/passwd
90 asynchronously: 71 asynchronously:
91 72
92 use Fcntl;
93 use EV; 73 use EV;
94 use IO::AIO; 74 use IO::AIO;
95 75
96 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
97 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98 78
99 # queue the request to open /etc/passwd 79 # queue the request to open /etc/passwd
100 aio_open "/etc/passwd", O_RDONLY, 0, sub { 80 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101 my $fh = shift 81 my $fh = shift
102 or die "error while opening: $!"; 82 or die "error while opening: $!";
103 83
104 # stat'ing filehandles is generally non-blocking 84 # stat'ing filehandles is generally non-blocking
105 my $size = -s $fh; 85 my $size = -s $fh;
… …
114 94
115 # file contents now in $contents 95 # file contents now in $contents
116 print $contents; 96 print $contents;
117 97
118 # exit event loop and program 98 # exit event loop and program
119 EV::unloop; 99 EV::break;
120 }; 100 };
121 }; 101 };
122 102
123 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
124 # check for sockets etc. etc. 104 # check for sockets etc. etc.
125 105
126 # process events as long as there are some: 106 # process events as long as there are some:
127 EV::loop; 107 EV::run;
128 108
129REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
130 Every "aio_*" function creates a request. which is a C data structure 110 Every "aio_*" function creates a request. which is a C data structure
131 not directly visible to Perl. 111 not directly visible to Perl.
132 112
… …
168 anymore (except possibly for the Perl object, but its connection to 148 anymore (except possibly for the Perl object, but its connection to
169 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
170 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
171 151
172FUNCTIONS 152FUNCTIONS
173 AIO REQUEST FUNCTIONS 153 QUICK OVERVIEW
154 This section simply lists the prototypes most of the functions for quick
155 reference. See the following sections for function-by-function
156 documentation.
157
158 aio_wd $pathname, $callback->($wd)
159 aio_open $pathname, $flags, $mode, $callback->($fh)
160 aio_close $fh, $callback->($status)
161 aio_seek $fh,$offset,$whence, $callback->($offs)
162 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
163 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
165 aio_readahead $fh,$offset,$length, $callback->($retval)
166 aio_stat $fh_or_path, $callback->($status)
167 aio_lstat $fh, $callback->($status)
168 aio_statvfs $fh_or_path, $callback->($statvfs)
169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
171 aio_chmod $fh_or_path, $mode, $callback->($status)
172 aio_truncate $fh_or_path, $offset, $callback->($status)
173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
175 aio_unlink $pathname, $callback->($status)
176 aio_mknod $pathname, $mode, $dev, $callback->($status)
177 aio_link $srcpath, $dstpath, $callback->($status)
178 aio_symlink $srcpath, $dstpath, $callback->($status)
179 aio_readlink $pathname, $callback->($link)
180 aio_realpath $pathname, $callback->($path)
181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
183 aio_mkdir $pathname, $mode, $callback->($status)
184 aio_rmdir $pathname, $callback->($status)
185 aio_readdir $pathname, $callback->($entries)
186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
188 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
190 aio_load $pathname, $data, $callback->($status)
191 aio_copy $srcpath, $dstpath, $callback->($status)
192 aio_move $srcpath, $dstpath, $callback->($status)
193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
198 aio_fsync $fh, $callback->($status)
199 aio_fdatasync $fh, $callback->($status)
200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
201 aio_pathsync $pathname, $callback->($status)
202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
205 aio_mlockall $flags, $callback->($status)
206 aio_group $callback->(...)
207 aio_nop $callback->()
208
209 $prev_pri = aioreq_pri [$pri]
210 aioreq_nice $pri_adjust
211
212 IO::AIO::poll_wait
213 IO::AIO::poll_cb
214 IO::AIO::poll
215 IO::AIO::flush
216 IO::AIO::max_poll_reqs $nreqs
217 IO::AIO::max_poll_time $seconds
218 IO::AIO::min_parallel $nthreads
219 IO::AIO::max_parallel $nthreads
220 IO::AIO::max_idle $nthreads
221 IO::AIO::idle_timeout $seconds
222 IO::AIO::max_outstanding $maxreqs
223 IO::AIO::nreqs
224 IO::AIO::nready
225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
230
231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
232 IO::AIO::fadvise $fh, $offset, $len, $advice
233
234 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
235 IO::AIO::munmap $scalar
236 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
237 IO::AIO::madvise $scalar, $offset, $length, $advice
238 IO::AIO::mprotect $scalar, $offset, $length, $protect
239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
240 IO::AIO::munlockall
241
242 # stat extensions
243 $counter = IO::AIO::st_gen
244 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
245 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
246 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
247 $seconds = IO::AIO::st_btimesec
248 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
249
250 # very much unportable syscalls
251 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
252 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
253 IO::AIO::tee $r_fh, $w_fh, $length, $flags
254 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
255 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
256 $fh = IO::AIO::memfd_create $pathname[, $flags]
257 $fh = IO::AIO::eventfd [$initval, [$flags]]
258 $fh = IO::AIO::timerfd_create $clockid[, $flags]
259 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
260 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
261
262 API NOTES
174 All the "aio_*" calls are more or less thin wrappers around the syscall 263 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 264 with the same name (sans "aio_"). The arguments are similar or
176 identical, and they all accept an additional (and optional) $callback 265 identical, and they all accept an additional (and optional) $callback
177 argument which must be a code reference. This code reference will get 266 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. 267 called after the syscall has been executed in an asynchronous fashion.
268 The results of the request will be passed as arguments to the callback
269 (and, if an error occured, in $!) - for most requests the syscall return
270 code (e.g. most syscalls return -1 on error, unlike perl, which usually
271 delivers "false").
272
273 Some requests (such as "aio_readdir") pass the actual results and
274 communicate failures by passing "undef".
181 275
182 All functions expecting a filehandle keep a copy of the filehandle 276 All functions expecting a filehandle keep a copy of the filehandle
183 internally until the request has finished. 277 internally until the request has finished.
184 278
185 All functions return request objects of type IO::AIO::REQ that allow 279 All functions return request objects of type IO::AIO::REQ that allow
186 further manipulation of those requests while they are in-flight. 280 further manipulation of those requests while they are in-flight.
187 281
188 The pathnames you pass to these routines *must* be absolute and encoded 282 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 283 reason for this is that at the time the request is being executed, the
190 being executed, the current working directory could have changed. 284 current working directory could have changed. Alternatively, you can
191 Alternatively, you can make sure that you never change the current 285 make sure that you never change the current working directory anywhere
192 working directory anywhere in the program and then use relative paths. 286 in the program and then use relative paths. You can also take advantage
287 of IO::AIOs working directory abstraction, that lets you specify paths
288 relative to some previously-opened "working directory object" - see the
289 description of the "IO::AIO::WD" class later in this document.
193 290
194 To encode pathnames as octets, either make sure you either: a) always 291 To encode pathnames as octets, either make sure you either: a) always
195 pass in filenames you got from outside (command line, readdir etc.) 292 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 293 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 294 Encode module and encode your pathnames to the locale (or other)
198 the user environment, d) use Glib::filename_from_unicode on unicode 295 encoding in effect in the user environment, d) use
199 filenames or e) use something else to ensure your scalar has the correct 296 Glib::filename_from_unicode on unicode filenames or e) use something
200 contents. 297 else to ensure your scalar has the correct contents.
201 298
202 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 299 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203 handles correctly whether it is set or not. 300 handles correctly whether it is set or not.
204 301
302 AIO REQUEST FUNCTIONS
205 $prev_pri = aioreq_pri [$pri] 303 $prev_pri = aioreq_pri [$pri]
206 Returns the priority value that would be used for the next request 304 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. 305 and, if $pri is given, sets the priority for the next aio request.
208 306
209 The default priority is 0, the minimum and maximum priorities are -4 307 The default priority is 0, the minimum and maximum priorities are -4
… …
231 Similar to "aioreq_pri", but subtracts the given value from the 329 Similar to "aioreq_pri", but subtracts the given value from the
232 current priority, so the effect is cumulative. 330 current priority, so the effect is cumulative.
233 331
234 aio_open $pathname, $flags, $mode, $callback->($fh) 332 aio_open $pathname, $flags, $mode, $callback->($fh)
235 Asynchronously open or create a file and call the callback with a 333 Asynchronously open or create a file and call the callback with a
236 newly created filehandle for the file. 334 newly created filehandle for the file (or "undef" in case of an
335 error).
237 336
238 The pathname passed to "aio_open" must be absolute. See API NOTES, 337 The pathname passed to "aio_open" must be absolute. See API NOTES,
239 above, for an explanation. 338 above, for an explanation.
240 339
241 The $flags argument is a bitmask. See the "Fcntl" module for a list. 340 The $flags argument is a bitmask. See the "Fcntl" module for a list.
… …
248 will be modified by the umask in effect then the request is being 347 will be modified by the umask in effect then the request is being
249 executed, so better never change the umask. 348 executed, so better never change the umask.
250 349
251 Example: 350 Example:
252 351
253 aio_open "/etc/passwd", O_RDONLY, 0, sub { 352 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254 if ($_[0]) { 353 if ($_[0]) {
255 print "open successful, fh is $_[0]\n"; 354 print "open successful, fh is $_[0]\n";
256 ... 355 ...
257 } else { 356 } else {
258 die "open failed: $!\n"; 357 die "open failed: $!\n";
259 } 358 }
260 }; 359 };
261 360
361 In addition to all the common open modes/flags ("O_RDONLY",
362 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
363 "O_APPEND"), the following POSIX and non-POSIX constants are
364 available (missing ones on your system are, as usual, 0):
365
366 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
367 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
368 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
369 and "O_ACCMODE".
370
262 aio_close $fh, $callback->($status) 371 aio_close $fh, $callback->($status)
263 Asynchronously close a file and call the callback with the result 372 Asynchronously close a file and call the callback with the result
264 code. 373 code.
265 374
266 Unfortunately, you can't do this to perl. Perl *insists* very 375 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 380 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). 381 a pipe (the pipe fd will be created on demand and will be cached).
273 382
274 Or in other words: the file descriptor will be closed, but it will 383 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. 384 not be free for reuse until the perl filehandle is closed.
385
386 aio_seek $fh, $offset, $whence, $callback->($offs)
387 Seeks the filehandle to the new $offset, similarly to perl's
388 "sysseek". The $whence can use the traditional values (0 for
389 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
390 "IO::AIO::SEEK_END").
391
392 The resulting absolute offset will be passed to the callback, or -1
393 in case of an error.
394
395 In theory, the $whence constants could be different than the
396 corresponding values from Fcntl, but perl guarantees they are the
397 same, so don't panic.
398
399 As a GNU/Linux (and maybe Solaris) extension, also the constants
400 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
401 could be found. No guarantees about suitability for use in
402 "aio_seek" or Perl's "sysseek" can be made though, although I would
403 naively assume they "just work".
276 404
277 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
278 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 406 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279 Reads or writes $length bytes from or to the specified $fh and 407 Reads or writes $length bytes from or to the specified $fh and
280 $offset into the scalar given by $data and offset $dataoffset and 408 $offset into the scalar given by $data and offset $dataoffset and
281 calls the callback without the actual number of bytes read (or -1 on 409 calls the callback with the actual number of bytes transferred (or
282 error, just like the syscall). 410 -1 on error, just like the syscall).
283 411
284 "aio_read" will, like "sysread", shrink or grow the $data scalar to 412 "aio_read" will, like "sysread", shrink or grow the $data scalar to
285 offset plus the actual number of bytes read. 413 offset plus the actual number of bytes read.
286 414
287 If $offset is undefined, then the current file descriptor offset 415 If $offset is undefined, then the current file descriptor offset
… …
309 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 437 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 438 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 439 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 440 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 441 more than one "aio_sendfile" per $out_fh, as they will interfere
314 with each other. 442 with each other. The same $in_fh works fine though, as this function
443 does not move or use the file offset of $in_fh.
315 444
445 Please note that "aio_sendfile" can read more bytes from $in_fh than
446 are written, and there is no way to find out how many more bytes
447 have been read from "aio_sendfile" alone, as "aio_sendfile" only
448 provides the number of bytes written to $out_fh. Only if the result
449 value equals $length one can assume that $length bytes have been
450 read.
451
452 Unlike with other "aio_" functions, it makes a lot of sense to use
453 "aio_sendfile" on non-blocking sockets, as long as one end
454 (typically the $in_fh) is a file - the file I/O will then be
455 asynchronous, while the socket I/O will be non-blocking. Note,
456 however, that you can run into a trap where "aio_sendfile" reads
457 some data with readahead, then fails to write all data, and when the
458 socket is ready the next time, the data in the cache is already
459 lost, forcing "aio_sendfile" to again hit the disk. Explicit
460 "aio_read" + "aio_write" let's you better control resource usage.
461
316 This call tries to make use of a native "sendfile" syscall to 462 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 463 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. 464 to a socket, and $in_fh should refer to an mmap'able file.
319 465
320 If the native sendfile call fails or is not implemented, it will be 466 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 467 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322 regardless of the limitations of the operating system. 468 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
469 any type of filehandle regardless of the limitations of the
470 operating system.
323 471
324 Please note, however, that "aio_sendfile" can read more bytes from 472 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 473 hacked together in a hurry to improve benchmark numbers) tend to be
326 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 474 rather buggy on many systems, this implementation tries to work
327 only provides the number of bytes written to $out_fh. Only if the 475 around some known bugs in Linux and FreeBSD kernels (probably
328 result value equals $length one can assume that $length bytes have 476 others, too), but that might fail, so you really really should check
329 been read. 477 the return value of "aio_sendfile" - fewer bytes than expected might
478 have been transferred.
330 479
331 aio_readahead $fh,$offset,$length, $callback->($retval) 480 aio_readahead $fh,$offset,$length, $callback->($retval)
332 "aio_readahead" populates the page cache with data from a file so 481 "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 482 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 483 $offset argument specifies the starting point from which data is to
… …
337 to a page boundary and bytes are read up to the next page boundary 486 to a page boundary and bytes are read up to the next page boundary
338 greater than or equal to (off-set+length). "aio_readahead" does not 487 greater than or equal to (off-set+length). "aio_readahead" does not
339 read beyond the end of the file. The current file offset of the file 488 read beyond the end of the file. The current file offset of the file
340 is left unchanged. 489 is left unchanged.
341 490
342 If that syscall doesn't exist (likely if your OS isn't Linux) it 491 If that syscall doesn't exist (likely if your kernel isn't Linux) it
343 will be emulated by simply reading the data, which would have a 492 will be emulated by simply reading the data, which would have a
344 similar effect. 493 similar effect.
345 494
346 aio_stat $fh_or_path, $callback->($status) 495 aio_stat $fh_or_path, $callback->($status)
347 aio_lstat $fh, $callback->($status) 496 aio_lstat $fh, $callback->($status)
348 Works like perl's "stat" or "lstat" in void context. The callback 497 Works almost exactly like perl's "stat" or "lstat" in void context.
349 will be called after the stat and the results will be available 498 The callback will be called after the stat and the results will be
350 using "stat _" or "-s _" etc... 499 available using "stat _" or "-s _" and other tests (with the
500 exception of "-B" and "-T").
351 501
352 The pathname passed to "aio_stat" must be absolute. See API NOTES, 502 The pathname passed to "aio_stat" must be absolute. See API NOTES,
353 above, for an explanation. 503 above, for an explanation.
354 504
355 Currently, the stats are always 64-bit-stats, i.e. instead of 505 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 506 returning an error when stat'ing a large file, the results will be
357 silently truncated unless perl itself is compiled with large file 507 silently truncated unless perl itself is compiled with large file
358 support. 508 support.
359 509
510 To help interpret the mode and dev/rdev stat values, IO::AIO offers
511 the following constants and functions (if not implemented, the
512 constants will be 0 and the functions will either "croak" or fall
513 back on traditional behaviour).
514
515 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
516 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
517 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
518
519 To access higher resolution stat timestamps, see "SUBSECOND STAT
520 TIME ACCESS".
521
360 Example: Print the length of /etc/passwd: 522 Example: Print the length of /etc/passwd:
361 523
362 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
363 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
364 print "size is ", -s _, "\n"; 526 print "size is ", -s _, "\n";
365 }; 527 };
366 528
529 aio_statvfs $fh_or_path, $callback->($statvfs)
530 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
531 whether a file handle or path was passed.
532
533 On success, the callback is passed a hash reference with the
534 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
535 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
536 failure, "undef" is passed.
537
538 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
539 and "ST_NOSUID".
540
541 The following non-POSIX IO::AIO::ST_* flag masks are defined to
542 their correct value when available, or to 0 on systems that do not
543 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
544 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
545 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
546
547 Example: stat "/wd" and dump out the data if successful.
548
549 aio_statvfs "/wd", sub {
550 my $f = $_[0]
551 or die "statvfs: $!";
552
553 use Data::Dumper;
554 say Dumper $f;
555 };
556
557 # result:
558 {
559 bsize => 1024,
560 bfree => 4333064312,
561 blocks => 10253828096,
562 files => 2050765568,
563 flag => 4096,
564 favail => 2042092649,
565 bavail => 4333064312,
566 ffree => 2042092649,
567 namemax => 255,
568 frsize => 1024,
569 fsid => 1810
570 }
571
367 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 572 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368 Works like perl's "utime" function (including the special case of 573 Works like perl's "utime" function (including the special case of
369 $atime and $mtime being undef). Fractional times are supported if 574 $atime and $mtime being undef). Fractional times are supported if
370 the underlying syscalls support them. 575 the underlying syscalls support them.
371 576
372 When called with a pathname, uses utimes(2) if available, otherwise 577 When called with a pathname, uses utimensat(2) or utimes(2) if
373 utime(2). If called on a file descriptor, uses futimes(2) if 578 available, otherwise utime(2). If called on a file descriptor, uses
374 available, otherwise returns ENOSYS, so this is not portable. 579 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
580 this is not portable.
375 581
376 Examples: 582 Examples:
377 583
378 # set atime and mtime to current time (basically touch(1)): 584 # set atime and mtime to current time (basically touch(1)):
379 aio_utime "path", undef, undef; 585 aio_utime "path", undef, undef;
… …
393 aio_chown "path", 0, undef; 599 aio_chown "path", 0, undef;
394 600
395 aio_truncate $fh_or_path, $offset, $callback->($status) 601 aio_truncate $fh_or_path, $offset, $callback->($status)
396 Works like truncate(2) or ftruncate(2). 602 Works like truncate(2) or ftruncate(2).
397 603
604 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
605 Allocates or frees disk space according to the $mode argument. See
606 the linux "fallocate" documentation for details.
607
608 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
609 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
610 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
611
612 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
613 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
614 "FALLOC_FL_INSERT_RANGE" to insert a range and
615 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
616 fallocate(2) manpage).
617
618 The file system block size used by "fallocate" is presumably the
619 "f_bsize" returned by "statvfs", but different filesystems and
620 filetypes can dictate other limitations.
621
622 If "fallocate" isn't available or cannot be emulated (currently no
623 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
624
398 aio_chmod $fh_or_path, $mode, $callback->($status) 625 aio_chmod $fh_or_path, $mode, $callback->($status)
399 Works like perl's "chmod" function. 626 Works like perl's "chmod" function.
400 627
401 aio_unlink $pathname, $callback->($status) 628 aio_unlink $pathname, $callback->($status)
402 Asynchronously unlink (delete) a file and call the callback with the 629 Asynchronously unlink (delete) a file and call the callback with the
403 result code. 630 result code.
404 631
405 aio_mknod $path, $mode, $dev, $callback->($status) 632 aio_mknod $pathname, $mode, $dev, $callback->($status)
406 [EXPERIMENTAL] 633 [EXPERIMENTAL]
407 634
408 Asynchronously create a device node (or fifo). See mknod(2). 635 Asynchronously create a device node (or fifo). See mknod(2).
409 636
410 The only (POSIX-) portable way of calling this function is: 637 The only (POSIX-) portable way of calling this function is:
411 638
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 639 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
640
641 See "aio_stat" for info about some potentially helpful extra
642 constants and functions.
413 643
414 aio_link $srcpath, $dstpath, $callback->($status) 644 aio_link $srcpath, $dstpath, $callback->($status)
415 Asynchronously create a new link to the existing object at $srcpath 645 Asynchronously create a new link to the existing object at $srcpath
416 at the path $dstpath and call the callback with the result code. 646 at the path $dstpath and call the callback with the result code.
417 647
418 aio_symlink $srcpath, $dstpath, $callback->($status) 648 aio_symlink $srcpath, $dstpath, $callback->($status)
419 Asynchronously create a new symbolic link to the existing object at 649 Asynchronously create a new symbolic link to the existing object at
420 $srcpath at the path $dstpath and call the callback with the result 650 $srcpath at the path $dstpath and call the callback with the result
421 code. 651 code.
422 652
423 aio_readlink $path, $callback->($link) 653 aio_readlink $pathname, $callback->($link)
424 Asynchronously read the symlink specified by $path and pass it to 654 Asynchronously read the symlink specified by $path and pass it to
425 the callback. If an error occurs, nothing or undef gets passed to 655 the callback. If an error occurs, nothing or undef gets passed to
426 the callback. 656 the callback.
427 657
658 aio_realpath $pathname, $callback->($path)
659 Asynchronously make the path absolute and resolve any symlinks in
660 $path. The resulting path only consists of directories (same as
661 Cwd::realpath).
662
663 This request can be used to get the absolute path of the current
664 working directory by passing it a path of . (a single dot).
665
428 aio_rename $srcpath, $dstpath, $callback->($status) 666 aio_rename $srcpath, $dstpath, $callback->($status)
429 Asynchronously rename the object at $srcpath to $dstpath, just as 667 Asynchronously rename the object at $srcpath to $dstpath, just as
430 rename(2) and call the callback with the result code. 668 rename(2) and call the callback with the result code.
669
670 On systems that support the AIO::WD working directory abstraction
671 natively, the case "[$wd, "."]" as $srcpath is specialcased -
672 instead of failing, "rename" is called on the absolute path of $wd.
673
674 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
675 Basically a version of "aio_rename" with an additional $flags
676 argument. Calling this with "$flags=0" is the same as calling
677 "aio_rename".
678
679 Non-zero flags are currently only supported on GNU/Linux systems
680 that support renameat2. Other systems fail with "ENOSYS" in this
681 case.
682
683 The following constants are available (missing ones are, as usual
684 0), see renameat2(2) for details:
685
686 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
687 "IO::AIO::RENAME_WHITEOUT".
431 688
432 aio_mkdir $pathname, $mode, $callback->($status) 689 aio_mkdir $pathname, $mode, $callback->($status)
433 Asynchronously mkdir (create) a directory and call the callback with 690 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 691 the result code. $mode will be modified by the umask at the time the
435 request is executed, so do not change your umask. 692 request is executed, so do not change your umask.
436 693
437 aio_rmdir $pathname, $callback->($status) 694 aio_rmdir $pathname, $callback->($status)
438 Asynchronously rmdir (delete) a directory and call the callback with 695 Asynchronously rmdir (delete) a directory and call the callback with
439 the result code. 696 the result code.
440 697
698 On systems that support the AIO::WD working directory abstraction
699 natively, the case "[$wd, "."]" is specialcased - instead of
700 failing, "rmdir" is called on the absolute path of $wd.
701
441 aio_readdir $pathname, $callback->($entries) 702 aio_readdir $pathname, $callback->($entries)
442 Unlike the POSIX call of the same name, "aio_readdir" reads an 703 Unlike the POSIX call of the same name, "aio_readdir" reads an
443 entire directory (i.e. opendir + readdir + closedir). The entries 704 entire directory (i.e. opendir + readdir + closedir). The entries
444 will not be sorted, and will NOT include the "." and ".." entries. 705 will not be sorted, and will NOT include the "." and ".." entries.
445 706
446 The callback is passed a single argument which is either "undef" or 707 The callback is passed a single argument which is either "undef" or
447 an array-ref with the filenames. 708 an array-ref with the filenames.
448 709
449 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 710 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
450 Quite similar to "aio_readdir", but the $flags argument allows to 711 Quite similar to "aio_readdir", but the $flags argument allows one
451 tune behaviour and output format. In case of an error, $entries will 712 to tune behaviour and output format. In case of an error, $entries
452 be "undef". 713 will be "undef".
453 714
454 The flags are a combination of the following constants, ORed 715 The flags are a combination of the following constants, ORed
455 together (the flags will also be passed to the callback, possibly 716 together (the flags will also be passed to the callback, possibly
456 modified): 717 modified):
457 718
458 IO::AIO::READDIR_DENTS 719 IO::AIO::READDIR_DENTS
459 When this flag is off, then the callback gets an arrayref with 720 Normally the callback gets an arrayref consisting of names only
460 of names only (as with "aio_readdir"), otherwise it gets an 721 (as with "aio_readdir"). If this flag is set, then the callback
461 arrayref with "[$name, $type, $inode]" arrayrefs, each 722 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462 describing a single directory entry in more detail. 723 describing a single directory entry in more detail:
463 724
464 $name is the name of the entry. 725 $name is the name of the entry.
465 726
466 $type is one of the "IO::AIO::DT_xxx" constants: 727 $type is one of the "IO::AIO::DT_xxx" constants:
467 728
468 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 729 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
469 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 730 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
470 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 731 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
471 732
472 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 733 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
473 you need to know, you have to run stat yourself. Also, for speed 734 you need to know, you have to run stat yourself. Also, for
474 reasons, the $type scalars are read-only: you can not modify 735 speed/memory reasons, the $type scalars are read-only: you must
475 them. 736 not modify them.
476 737
477 $inode is the inode number (which might not be exact on systems 738 $inode is the inode number (which might not be exact on systems
478 with 64 bit inode numbers and 32 bit perls). This field has 739 with 64 bit inode numbers and 32 bit perls). This field has
479 unspecified content on systems that do not deliver the inode 740 unspecified content on systems that do not deliver the inode
480 information. 741 information.
481 742
482 IO::AIO::READDIR_DIRS_FIRST 743 IO::AIO::READDIR_DIRS_FIRST
483 When this flag is set, then the names will be returned in an 744 When this flag is set, then the names will be returned in an
484 order where likely directories come first. This is useful when 745 order where likely directories come first, in optimal stat
485 you need to quickly find directories, or you want to find all 746 order. This is useful when you need to quickly find directories,
486 directories while avoiding to stat() each entry. 747 or you want to find all directories while avoiding to stat()
748 each entry.
487 749
488 If the system returns type information in readdir, then this is 750 If the system returns type information in readdir, then this is
489 used to find directories directly. Otherwise, likely directories 751 used to find directories directly. Otherwise, likely directories
490 are files beginning with ".", or otherwise files with no dots, 752 are names beginning with ".", or otherwise names with no dots,
491 of which files with short names are tried first. 753 of which names with short names are tried first.
492 754
493 IO::AIO::READDIR_STAT_ORDER 755 IO::AIO::READDIR_STAT_ORDER
494 When this flag is set, then the names will be returned in an 756 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 757 order suitable for stat()'ing each one. That is, when you plan
496 to stat() all files in the given directory, then the returned 758 to stat() most or all files in the given directory, then the
497 order will likely be fastest. 759 returned order will likely be faster.
498 760
499 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 761 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
500 specified, then the likely dirs come first, resulting in a less 762 specified, then the likely dirs come first, resulting in a less
501 optimal stat order. 763 optimal stat order for stat'ing all entries, but likely a more
764 optimal order for finding subdirectories.
502 765
503 IO::AIO::READDIR_FOUND_UNKNOWN 766 IO::AIO::READDIR_FOUND_UNKNOWN
504 This flag should not be set when calling "aio_readdirx". 767 This flag should not be set when calling "aio_readdirx".
505 Instead, it is being set by "aio_readdirx", when any of the 768 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 769 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
507 flag therefore indicates that all $type's are known, which can 770 flag therefore indicates that all $type's are known, which can
508 be used to speed up some algorithms. 771 be used to speed up some algorithms.
509 772
773 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
774 Opens, reads and closes the given file. The data is put into $data,
775 which is resized as required.
776
777 If $offset is negative, then it is counted from the end of the file.
778
779 If $length is zero, then the remaining length of the file is used.
780 Also, in this case, the same limitations to modifying $data apply as
781 when IO::AIO::mmap is used, i.e. it must only be modified in-place
782 with "substr". If the size of the file is known, specifying a
783 non-zero $length results in a performance advantage.
784
785 This request is similar to the older "aio_load" request, but since
786 it is a single request, it might be more efficient to use.
787
788 Example: load /etc/passwd into $passwd.
789
790 my $passwd;
791 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
792 $_[0] >= 0
793 or die "/etc/passwd: $!\n";
794
795 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
796 print $passwd;
797 };
798 IO::AIO::flush;
799
510 aio_load $path, $data, $callback->($status) 800 aio_load $pathname, $data, $callback->($status)
511 This is a composite request that tries to fully load the given file 801 This is a composite request that tries to fully load the given file
512 into memory. Status is the same as with aio_read. 802 into memory. Status is the same as with aio_read.
803
804 Using "aio_slurp" might be more efficient, as it is a single
805 request.
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 a status of 0 (ok) or -1 (error, see $!). 810 a status of 0 (ok) or -1 (error, see $!).
518 811
812 Existing destination files will be truncated.
813
519 This is a composite request that creates the destination file with 814 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 815 mode 0200 and copies the contents of the source file into it using
521 "aio_sendfile", followed by restoring atime, mtime, access mode and 816 "aio_sendfile", followed by restoring atime, mtime, access mode and
522 uid/gid, in that order. 817 uid/gid, in that order.
523 818
… …
532 827
533 This is a composite request that tries to rename(2) the file first; 828 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" 829 if rename fails with "EXDEV", it copies the file with "aio_copy"
535 and, if that is successful, unlinks the $srcpath. 830 and, if that is successful, unlinks the $srcpath.
536 831
537 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 832 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
538 Scans a directory (similar to "aio_readdir") but additionally tries 833 Scans a directory (similar to "aio_readdir") but additionally tries
539 to efficiently separate the entries of directory $path into two sets 834 to efficiently separate the entries of directory $path into two sets
540 of names, directories you can recurse into (directories), and ones 835 of names, directories you can recurse into (directories), and ones
541 you cannot recurse into (everything else, including symlinks to 836 you cannot recurse into (everything else, including symlinks to
542 directories). 837 directories).
543 838
544 "aio_scandir" is a composite request that creates of many sub 839 "aio_scandir" is a composite request that generates many sub
545 requests_ $maxreq specifies the maximum number of outstanding aio 840 requests. $maxreq specifies the maximum number of outstanding aio
546 requests that this function generates. If it is "<= 0", then a 841 requests that this function generates. If it is "<= 0", then a
547 suitable default will be chosen (currently 4). 842 suitable default will be chosen (currently 4).
548 843
549 On error, the callback is called without arguments, otherwise it 844 On error, the callback is called without arguments, otherwise it
550 receives two array-refs with path-relative entry names. 845 receives two array-refs with path-relative entry names.
… …
575 Then entries will be sorted into likely directories a non-initial 870 Then entries will be sorted into likely directories a non-initial
576 dot currently) and likely non-directories (see "aio_readdirx"). Then 871 dot currently) and likely non-directories (see "aio_readdirx"). Then
577 every entry plus an appended "/." will be "stat"'ed, likely 872 every entry plus an appended "/." will be "stat"'ed, likely
578 directories first, in order of their inode numbers. If that 873 directories first, in order of their inode numbers. If that
579 succeeds, it assumes that the entry is a directory or a symlink to 874 succeeds, it assumes that the entry is a directory or a symlink to
580 directory (which will be checked seperately). This is often faster 875 directory (which will be checked separately). This is often faster
581 than stat'ing the entry itself because filesystems might detect the 876 than stat'ing the entry itself because filesystems might detect the
582 type of the entry without reading the inode data (e.g. ext2fs 877 type of the entry without reading the inode data (e.g. ext2fs
583 filetype feature), even on systems that cannot return the filetype 878 filetype feature), even on systems that cannot return the filetype
584 information on readdir. 879 information on readdir.
585 880
… …
591 886
592 It will also likely work on non-POSIX filesystems with reduced 887 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 888 efficiency as those tend to return 0 or 1 as link counts, which
594 disables the directory counting heuristic. 889 disables the directory counting heuristic.
595 890
596 aio_rmtree $path, $callback->($status) 891 aio_rmtree $pathname, $callback->($status)
597 Delete a directory tree starting (and including) $path, return the 892 Delete a directory tree starting (and including) $path, return the
598 status of the final "rmdir" only. This is a composite request that 893 status of the final "rmdir" only. This is a composite request that
599 uses "aio_scandir" to recurse into and rmdir directories, and unlink 894 uses "aio_scandir" to recurse into and rmdir directories, and unlink
600 everything else. 895 everything else.
601 896
897 aio_fcntl $fh, $cmd, $arg, $callback->($status)
898 aio_ioctl $fh, $request, $buf, $callback->($status)
899 These work just like the "fcntl" and "ioctl" built-in functions,
900 except they execute asynchronously and pass the return value to the
901 callback.
902
903 Both calls can be used for a lot of things, some of which make more
904 sense to run asynchronously in their own thread, while some others
905 make less sense. For example, calls that block waiting for external
906 events, such as locking, will also lock down an I/O thread while it
907 is waiting, which can deadlock the whole I/O system. At the same
908 time, there might be no alternative to using a thread to wait.
909
910 So in general, you should only use these calls for things that do
911 (filesystem) I/O, not for things that wait for other events
912 (network, other processes), although if you are careful and know
913 what you are doing, you still can.
914
915 The following constants are available and can be used for normal
916 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
917
918 "F_DUPFD_CLOEXEC",
919
920 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
921
922 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
923 "FIDEDUPERANGE".
924
925 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
926 "F_SEAL_GROW" and "F_SEAL_WRITE".
927
928 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
929 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
930
931 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
932 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
933 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
934
935 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
936 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
937 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
938 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
939 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
940
941 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
942 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
943 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
944 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
945 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
946 "FS_XFLAG_HASATTR",
947
602 aio_sync $callback->($status) 948 aio_sync $callback->($status)
603 Asynchronously call sync and call the callback when finished. 949 Asynchronously call sync and call the callback when finished.
604 950
605 aio_fsync $fh, $callback->($status) 951 aio_fsync $fh, $callback->($status)
606 Asynchronously call fsync on the given filehandle and call the 952 Asynchronously call fsync on the given filehandle and call the
… …
610 Asynchronously call fdatasync on the given filehandle and call the 956 Asynchronously call fdatasync on the given filehandle and call the
611 callback with the fdatasync result code. 957 callback with the fdatasync result code.
612 958
613 If this call isn't available because your OS lacks it or it couldn't 959 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. 960 be detected, it will be emulated by calling "fsync" instead.
961
962 aio_syncfs $fh, $callback->($status)
963 Asynchronously call the syncfs syscall to sync the filesystem
964 associated to the given filehandle and call the callback with the
965 syncfs result code. If syncfs is not available, calls sync(), but
966 returns -1 and sets errno to "ENOSYS" nevertheless.
615 967
616 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 968 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
617 Sync the data portion of the file specified by $offset and $length 969 Sync the data portion of the file specified by $offset and $length
618 to disk (but NOT the metadata), by calling the Linux-specific 970 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 971 sync_file_range call. If sync_file_range is not available or it
… …
623 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 975 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
624 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 976 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
625 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 977 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
626 manpage for details. 978 manpage for details.
627 979
628 aio_pathsync $path, $callback->($status) 980 aio_pathsync $pathname, $callback->($status)
629 This request tries to open, fsync and close the given path. This is 981 This request tries to open, fsync and close the given path. This is
630 a composite request intended to sync directories after directory 982 a composite request intended to sync directories after directory
631 operations (E.g. rename). This might not work on all operating 983 operations (E.g. rename). This might not work on all operating
632 systems or have any specific effect, but usually it makes sure that 984 systems or have any specific effect, but usually it makes sure that
633 directory changes get written to disc. It works for anything that 985 directory changes get written to disc. It works for anything that
… …
636 Future versions of this function might fall back to other methods 988 Future versions of this function might fall back to other methods
637 when "fsync" on the directory fails (such as calling "sync"). 989 when "fsync" on the directory fails (such as calling "sync").
638 990
639 Passes 0 when everything went ok, and -1 on error. 991 Passes 0 when everything went ok, and -1 on error.
640 992
993 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
994 $callback->($status)
995 This is a rather advanced IO::AIO call, which only works on
996 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
997 also works on data scalars managed by the Sys::Mmap or Mmap modules,
998 note that the scalar must only be modified in-place while an aio
999 operation is pending on it).
1000
1001 It calls the "msync" function of your OS, if available, with the
1002 memory area starting at $offset in the string and ending $length
1003 bytes later. If $length is negative, counts from the end, and if
1004 $length is "undef", then it goes till the end of the string. The
1005 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
1006 an optional "IO::AIO::MS_INVALIDATE".
1007
1008 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
1009 $callback->($status)
1010 This is a rather advanced IO::AIO call, which works best on
1011 mmap(2)ed scalars.
1012
1013 It touches (reads or writes) all memory pages in the specified range
1014 inside the scalar. All caveats and parameters are the same as for
1015 "aio_msync", above, except for flags, which must be either 0 (which
1016 reads all pages and ensures they are instantiated) or
1017 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
1018 and writing an octet from it, which dirties the page).
1019
1020 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1021 This is a rather advanced IO::AIO call, which works best on
1022 mmap(2)ed scalars.
1023
1024 It reads in all the pages of the underlying storage into memory (if
1025 any) and locks them, so they are not getting swapped/paged out or
1026 removed.
1027
1028 If $length is undefined, then the scalar will be locked till the
1029 end.
1030
1031 On systems that do not implement "mlock", this function returns -1
1032 and sets errno to "ENOSYS".
1033
1034 Note that the corresponding "munlock" is synchronous and is
1035 documented under "MISCELLANEOUS FUNCTIONS".
1036
1037 Example: open a file, mmap and mlock it - both will be undone when
1038 $data gets destroyed.
1039
1040 open my $fh, "<", $path or die "$path: $!";
1041 my $data;
1042 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1043 aio_mlock $data; # mlock in background
1044
1045 aio_mlockall $flags, $callback->($status)
1046 Calls the "mlockall" function with the given $flags (a combination
1047 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1048 "IO::AIO::MCL_ONFAULT").
1049
1050 On systems that do not implement "mlockall", this function returns
1051 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1052 supported by the system result in a return value of -1 with errno
1053 being set to "EINVAL".
1054
1055 Note that the corresponding "munlockall" is synchronous and is
1056 documented under "MISCELLANEOUS FUNCTIONS".
1057
1058 Example: asynchronously lock all current and future pages into
1059 memory.
1060
1061 aio_mlockall IO::AIO::MCL_FUTURE;
1062
1063 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1064 Queries the extents of the given file (by calling the Linux "FIEMAP"
1065 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1066 details). If the ioctl is not available on your OS, then this
1067 request will fail with "ENOSYS".
1068
1069 $start is the starting offset to query extents for, $length is the
1070 size of the range to query - if it is "undef", then the whole file
1071 will be queried.
1072
1073 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1074 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1075 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1076 query the data portion.
1077
1078 $count is the maximum number of extent records to return. If it is
1079 "undef", then IO::AIO queries all extents of the range. As a very
1080 special case, if it is 0, then the callback receives the number of
1081 extents instead of the extents themselves (which is unreliable, see
1082 below).
1083
1084 If an error occurs, the callback receives no arguments. The special
1085 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1086
1087 Otherwise, the callback receives an array reference with extent
1088 structures. Each extent structure is an array reference itself, with
1089 the following members:
1090
1091 [$logical, $physical, $length, $flags]
1092
1093 Flags is any combination of the following flag values (typically
1094 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1095
1096 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1097 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1098 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1099 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1100 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1101 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1102 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1103 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1104
1105 At the time of this writing (Linux 3.2), this request is unreliable
1106 unless $count is "undef", as the kernel has all sorts of bugs
1107 preventing it to return all extents of a range for files with a
1108 large number of extents. The code (only) works around all these
1109 issues if $count is "undef".
1110
641 aio_group $callback->(...) 1111 aio_group $callback->(...)
642 This is a very special aio request: Instead of doing something, it 1112 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 1113 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 1114 to bundle many requests into a single, composite, request with a
645 definite callback and the ability to cancel the whole request with 1115 definite callback and the ability to cancel the whole request with
… …
678 While it is theoretically handy to have simple I/O scheduling 1148 While it is theoretically handy to have simple I/O scheduling
679 requests like sleep and file handle readable/writable, the overhead 1149 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 1150 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 1151 not use this function except to put your application under
682 artificial I/O pressure. 1152 artificial I/O pressure.
1153
1154 IO::AIO::WD - multiple working directories
1155 Your process only has one current working directory, which is used by
1156 all threads. This makes it hard to use relative paths (some other
1157 component could call "chdir" at any time, and it is hard to control when
1158 the path will be used by IO::AIO).
1159
1160 One solution for this is to always use absolute paths. This usually
1161 works, but can be quite slow (the kernel has to walk the whole path on
1162 every access), and can also be a hassle to implement.
1163
1164 Newer POSIX systems have a number of functions (openat, fdopendir,
1165 futimensat and so on) that make it possible to specify working
1166 directories per operation.
1167
1168 For portability, and because the clowns who "designed", or shall I
1169 write, perpetrated this new interface were obviously half-drunk, this
1170 abstraction cannot be perfect, though.
1171
1172 IO::AIO allows you to convert directory paths into a so-called
1173 IO::AIO::WD object. This object stores the canonicalised, absolute
1174 version of the path, and on systems that allow it, also a directory file
1175 descriptor.
1176
1177 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1178 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1179 object and a pathname instead (or the IO::AIO::WD object alone, which
1180 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1181 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1182 relative to that IO::AIO::WD object.
1183
1184 For example, to get a wd object for /etc and then stat passwd inside,
1185 you would write:
1186
1187 aio_wd "/etc", sub {
1188 my $etcdir = shift;
1189
1190 # although $etcdir can be undef on error, there is generally no reason
1191 # to check for errors here, as aio_stat will fail with ENOENT
1192 # when $etcdir is undef.
1193
1194 aio_stat [$etcdir, "passwd"], sub {
1195 # yay
1196 };
1197 };
1198
1199 The fact that "aio_wd" is a request and not a normal function shows that
1200 creating an IO::AIO::WD object is itself a potentially blocking
1201 operation, which is why it is done asynchronously.
1202
1203 To stat the directory obtained with "aio_wd" above, one could write
1204 either of the following three request calls:
1205
1206 aio_lstat "/etc" , sub { ... # pathname as normal string
1207 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1208 aio_lstat $wd , sub { ... # shorthand for the previous
1209
1210 As with normal pathnames, IO::AIO keeps a copy of the working directory
1211 object and the pathname string, so you could write the following without
1212 causing any issues due to $path getting reused:
1213
1214 my $path = [$wd, undef];
1215
1216 for my $name (qw(abc def ghi)) {
1217 $path->[1] = $name;
1218 aio_stat $path, sub {
1219 # ...
1220 };
1221 }
1222
1223 There are some caveats: when directories get renamed (or deleted), the
1224 pathname string doesn't change, so will point to the new directory (or
1225 nowhere at all), while the directory fd, if available on the system,
1226 will still point to the original directory. Most functions accepting a
1227 pathname will use the directory fd on newer systems, and the string on
1228 older systems. Some functions (such as "aio_realpath") will always rely
1229 on the string form of the pathname.
1230
1231 So this functionality is mainly useful to get some protection against
1232 "chdir", to easily get an absolute path out of a relative path for
1233 future reference, and to speed up doing many operations in the same
1234 directory (e.g. when stat'ing all files in a directory).
1235
1236 The following functions implement this working directory abstraction:
1237
1238 aio_wd $pathname, $callback->($wd)
1239 Asynchonously canonicalise the given pathname and convert it to an
1240 IO::AIO::WD object representing it. If possible and supported on the
1241 system, also open a directory fd to speed up pathname resolution
1242 relative to this working directory.
1243
1244 If something goes wrong, then "undef" is passwd to the callback
1245 instead of a working directory object and $! is set appropriately.
1246 Since passing "undef" as working directory component of a pathname
1247 fails the request with "ENOENT", there is often no need for error
1248 checking in the "aio_wd" callback, as future requests using the
1249 value will fail in the expected way.
1250
1251 IO::AIO::CWD
1252 This is a compile time constant (object) that represents the process
1253 current working directory.
1254
1255 Specifying this object as working directory object for a pathname is
1256 as if the pathname would be specified directly, without a directory
1257 object. For example, these calls are functionally identical:
1258
1259 aio_stat "somefile", sub { ... };
1260 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1261
1262 To recover the path associated with an IO::AIO::WD object, you can use
1263 "aio_realpath":
1264
1265 aio_realpath $wd, sub {
1266 warn "path is $_[0]\n";
1267 };
1268
1269 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1270 sometimes, fall back to using an absolue path.
683 1271
684 IO::AIO::REQ CLASS 1272 IO::AIO::REQ CLASS
685 All non-aggregate "aio_*" functions return an object of this class when 1273 All non-aggregate "aio_*" functions return an object of this class when
686 called in non-void context. 1274 called in non-void context.
687 1275
… …
761 $grp->cancel_subs 1349 $grp->cancel_subs
762 Cancel all subrequests and clears any feeder, but not the group 1350 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 1351 request itself. Useful when you queued a lot of events but got a
764 result early. 1352 result early.
765 1353
1354 The group request will finish normally (you cannot add requests to
1355 the group).
1356
766 $grp->result (...) 1357 $grp->result (...)
767 Set the result value(s) that will be passed to the group callback 1358 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 1359 when all subrequests have finished and set the groups errno to the
769 current value of errno (just like calling "errno" without an error 1360 current value of errno (just like calling "errno" without an error
770 number). By default, no argument will be passed and errno is zero. 1361 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 1375 Sets a feeder/generator on this group: every group can have an
785 attached generator that generates requests if idle. The idea behind 1376 attached generator that generates requests if idle. The idea behind
786 this is that, although you could just queue as many requests as you 1377 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 1378 want in a group, this might starve other requests for a potentially
788 long time. For example, "aio_scandir" might generate hundreds of 1379 long time. For example, "aio_scandir" might generate hundreds of
789 thousands "aio_stat" requests, delaying any later requests for a 1380 thousands of "aio_stat" requests, delaying any later requests for a
790 long time. 1381 long time.
791 1382
792 To avoid this, and allow incremental generation of requests, you can 1383 To avoid this, and allow incremental generation of requests, you can
793 instead a group and set a feeder on it that generates those 1384 instead a group and set a feeder on it that generates those
794 requests. The feed callback will be called whenever there are few 1385 requests. The feed callback will be called whenever there are few
… …
836 results. 1427 results.
837 1428
838 See "poll_cb" for an example. 1429 See "poll_cb" for an example.
839 1430
840 IO::AIO::poll_cb 1431 IO::AIO::poll_cb
841 Process some outstanding events on the result pipe. You have to call 1432 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 1433 have been executed but the results are not yet reported). You have
843 it returned earlier for whatever reason. Returns immediately when no 1434 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 1435
1436 Returns 0 if all events could be processed (or there were no events
1437 to process), or -1 if it returned earlier for whatever reason.
1438 Returns immediately when no events are outstanding. The amount of
1439 events processed depends on the settings of "IO::AIO::max_poll_req",
1440 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1441
848 If not all requests were processed for whatever reason, the 1442 If not all requests were processed for whatever reason, the poll
849 filehandle will still be ready when "poll_cb" returns, so normally 1443 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. 1444 normally you don't have to do anything special to have it called
1445 later.
1446
1447 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1448 becomes ready, it can be beneficial to call this function from loops
1449 which submit a lot of requests, to make sure the results get
1450 processed when they become available and not just when the loop is
1451 finished and the event loop takes over again. This function returns
1452 very fast when there are no outstanding requests.
851 1453
852 Example: Install an Event watcher that automatically calls 1454 Example: Install an Event watcher that automatically calls
853 IO::AIO::poll_cb with high priority (more examples can be found in 1455 IO::AIO::poll_cb with high priority (more examples can be found in
854 the SYNOPSIS section, at the top of this document): 1456 the SYNOPSIS section, at the top of this document):
855 1457
856 Event->io (fd => IO::AIO::poll_fileno, 1458 Event->io (fd => IO::AIO::poll_fileno,
857 poll => 'r', async => 1, 1459 poll => 'r', async => 1,
858 cb => \&IO::AIO::poll_cb); 1460 cb => \&IO::AIO::poll_cb);
1461
1462 IO::AIO::poll_wait
1463 Wait until either at least one request is in the result phase or no
1464 requests are outstanding anymore.
1465
1466 This is useful if you want to synchronously wait for some requests
1467 to become ready, without actually handling them.
1468
1469 See "nreqs" for an example.
1470
1471 IO::AIO::poll
1472 Waits until some requests have been handled.
1473
1474 Returns the number of requests processed, but is otherwise strictly
1475 equivalent to:
1476
1477 IO::AIO::poll_wait, IO::AIO::poll_cb
1478
1479 IO::AIO::flush
1480 Wait till all outstanding AIO requests have been handled.
1481
1482 Strictly equivalent to:
1483
1484 IO::AIO::poll_wait, IO::AIO::poll_cb
1485 while IO::AIO::nreqs;
1486
1487 This function can be useful at program aborts, to make sure
1488 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1489 already calls this function on normal exits), or when you are merely
1490 using "IO::AIO" for its more advanced functions, rather than for
1491 async I/O, e.g.:
1492
1493 my ($dirs, $nondirs);
1494 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1495 IO::AIO::flush;
1496 # $dirs, $nondirs are now set
859 1497
860 IO::AIO::max_poll_reqs $nreqs 1498 IO::AIO::max_poll_reqs $nreqs
861 IO::AIO::max_poll_time $seconds 1499 IO::AIO::max_poll_time $seconds
862 These set the maximum number of requests (default 0, meaning 1500 These set the maximum number of requests (default 0, meaning
863 infinity) that are being processed by "IO::AIO::poll_cb" in one 1501 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
887 # use a low priority so other tasks have priority 1525 # use a low priority so other tasks have priority
888 Event->io (fd => IO::AIO::poll_fileno, 1526 Event->io (fd => IO::AIO::poll_fileno,
889 poll => 'r', nice => 1, 1527 poll => 'r', nice => 1,
890 cb => &IO::AIO::poll_cb); 1528 cb => &IO::AIO::poll_cb);
891 1529
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 1530 CONTROLLING THE NUMBER OF THREADS
917 IO::AIO::min_parallel $nthreads 1531 IO::AIO::min_parallel $nthreads
918 Set the minimum number of AIO threads to $nthreads. The current 1532 Set the minimum number of AIO threads to $nthreads. The current
919 default is 8, which means eight asynchronous operations can execute 1533 default is 8, which means eight asynchronous operations can execute
920 concurrently at any one time (the number of outstanding requests, 1534 concurrently at any one time (the number of outstanding requests,
… …
949 1563
950 Under normal circumstances you don't need to call this function. 1564 Under normal circumstances you don't need to call this function.
951 1565
952 IO::AIO::max_idle $nthreads 1566 IO::AIO::max_idle $nthreads
953 Limit the number of threads (default: 4) that are allowed to idle 1567 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 1568 (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 1569 timeout (default: 10 seconds). That means if a thread becomes idle
956 threads are also idle, it will free its resources and exit. 1570 while $nthreads other threads are also idle, it will free its
1571 resources and exit.
957 1572
958 This is useful when you allow a large number of threads (e.g. 100 or 1573 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 1574 1000) to allow for extremely high load situations, but want to free
960 resources under normal circumstances (1000 threads can easily 1575 resources under normal circumstances (1000 threads can easily
961 consume 30MB of RAM). 1576 consume 30MB of RAM).
962 1577
963 The default is probably ok in most situations, especially if thread 1578 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 1579 creation is fast. If thread creation is very slow on your system you
965 might want to use larger values. 1580 might want to use larger values.
966 1581
1582 IO::AIO::idle_timeout $seconds
1583 Sets the minimum idle timeout (default 10) after which worker
1584 threads are allowed to exit. SEe "IO::AIO::max_idle".
1585
967 IO::AIO::max_outstanding $maxreqs 1586 IO::AIO::max_outstanding $maxreqs
1587 Sets the maximum number of outstanding requests to $nreqs. If you do
1588 queue up more than this number of requests, the next call to
1589 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
1590 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1591 no longer exceeded.
1592
1593 In other words, this setting does not enforce a queue limit, but can
1594 be used to make poll functions block if the limit is exceeded.
1595
968 This is a very bad function to use in interactive programs because 1596 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 1597 it blocks, and a bad way to reduce concurrency because it is
970 inexact: Better use an "aio_group" together with a feed callback. 1598 inexact: Better use an "aio_group" together with a feed callback.
971 1599
972 Sets the maximum number of outstanding requests to $nreqs. If you do 1600 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 1601 stat a lot of files, you can write something 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 1602
977 The default value is very large, so there is no practical limit on 1603 IO::AIO::max_outstanding 32;
1604
1605 for my $path (...) {
1606 aio_stat $path , ...;
1607 IO::AIO::poll_cb;
1608 }
1609
1610 IO::AIO::flush;
1611
1612 The call to "poll_cb" inside the loop will normally return
1613 instantly, but as soon as more thna 32 reqeusts are in-flight, it
1614 will block until some requests have been handled. This keeps the
1615 loop from pushing a large number of "aio_stat" requests onto the
1616 queue.
1617
1618 The default value for "max_outstanding" is very large, so there is
978 the number of outstanding requests. 1619 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 1620
985 STATISTICAL INFORMATION 1621 STATISTICAL INFORMATION
986 IO::AIO::nreqs 1622 IO::AIO::nreqs
987 Returns the number of requests currently in the ready, execute or 1623 Returns the number of requests currently in the ready, execute or
988 pending states (i.e. for which their callback has not been invoked 1624 pending states (i.e. for which their callback has not been invoked
… …
999 1635
1000 IO::AIO::npending 1636 IO::AIO::npending
1001 Returns the number of requests currently in the pending state 1637 Returns the number of requests currently in the pending state
1002 (executed, but not yet processed by poll_cb). 1638 (executed, but not yet processed by poll_cb).
1003 1639
1640 SUBSECOND STAT TIME ACCESS
1641 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1642 generally find access/modification and change times with subsecond time
1643 accuracy of the system supports it, but perl's built-in functions only
1644 return the integer part.
1645
1646 The following functions return the timestamps of the most recent stat
1647 with subsecond precision on most systems and work both after
1648 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1649 value is only meaningful after a successful "stat"/"lstat" call, or
1650 during/after a successful "aio_stat"/"aio_lstat" callback.
1651
1652 This is similar to the Time::HiRes "stat" functions, but can return full
1653 resolution without rounding and work with standard perl "stat",
1654 alleviating the need to call the special "Time::HiRes" functions, which
1655 do not act like their perl counterparts.
1656
1657 On operating systems or file systems where subsecond time resolution is
1658 not supported or could not be detected, a fractional part of 0 is
1659 returned, so it is always safe to call these functions.
1660
1661 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1662 IO::AIO::st_btime
1663 Return the access, modication, change or birth time, respectively,
1664 including fractional part. Due to the limited precision of floating
1665 point, the accuracy on most platforms is only a bit better than
1666 milliseconds for times around now - see the *nsec* function family,
1667 below, for full accuracy.
1668
1669 File birth time is only available when the OS and perl support it
1670 (on FreeBSD and NetBSD at the time of this writing, although support
1671 is adaptive, so if your OS/perl gains support, IO::AIO can take
1672 advantage of it). On systems where it isn't available, 0 is
1673 currently returned, but this might change to "undef" in a future
1674 version.
1675
1676 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1677 Returns access, modification, change and birth time all in one go,
1678 and maybe more times in the future version.
1679
1680 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1681 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1682 Return the fractional access, modifcation, change or birth time, in
1683 nanoseconds, as an integer in the range 0 to 999999999.
1684
1685 Note that no accessors are provided for access, modification and
1686 change times - you need to get those from "stat _" if required ("int
1687 IO::AIO::st_atime" and so on will *not* generally give you the
1688 correct value).
1689
1690 $seconds = IO::AIO::st_btimesec
1691 The (integral) seconds part of the file birth time, if available.
1692
1693 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1694 Like the functions above, but returns all four times in one go (and
1695 maybe more in future versions).
1696
1697 $counter = IO::AIO::st_gen
1698 Returns the generation counter (in practice this is just a random
1699 number) of the file. This is only available on platforms which have
1700 this member in their "struct stat" (most BSDs at the time of this
1701 writing) and generally only to the root usert. If unsupported, 0 is
1702 returned, but this might change to "undef" in a future version.
1703
1704 Example: print the high resolution modification time of /etc, using
1705 "stat", and "IO::AIO::aio_stat".
1706
1707 if (stat "/etc") {
1708 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1709 }
1710
1711 IO::AIO::aio_stat "/etc", sub {
1712 $_[0]
1713 and return;
1714
1715 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1716 };
1717
1718 IO::AIO::flush;
1719
1720 Output of the awbove on my system, showing reduced and full accuracy:
1721
1722 stat(/etc) mtime: 1534043702.020808
1723 aio_stat(/etc) mtime: 1534043702.020807792
1724
1004 MISCELLANEOUS FUNCTIONS 1725 MISCELLANEOUS FUNCTIONS
1005 IO::AIO implements some functions that might be useful, but are not 1726 IO::AIO implements some functions that are useful when you want to use
1006 asynchronous. 1727 some "Advanced I/O" function not available to in Perl, without going the
1728 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1729 counterpart.
1730
1731 $numfd = IO::AIO::get_fdlimit
1732 Tries to find the current file descriptor limit and returns it, or
1733 "undef" and sets $! in case of an error. The limit is one larger
1734 than the highest valid file descriptor number.
1735
1736 IO::AIO::min_fdlimit [$numfd]
1737 Try to increase the current file descriptor limit(s) to at least
1738 $numfd by changing the soft or hard file descriptor resource limit.
1739 If $numfd is missing, it will try to set a very high limit, although
1740 this is not recommended when you know the actual minimum that you
1741 require.
1742
1743 If the limit cannot be raised enough, the function makes a
1744 best-effort attempt to increase the limit as much as possible, using
1745 various tricks, while still failing. You can query the resulting
1746 limit using "IO::AIO::get_fdlimit".
1747
1748 If an error occurs, returns "undef" and sets $!, otherwise returns
1749 true.
1007 1750
1008 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1009 Calls the "eio_sendfile_sync" function, which is like 1752 Calls the "eio_sendfile_sync" function, which is like
1010 "aio_sendfile", but is blocking (this makes most sense if you know 1753 "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 1754 the input data is likely cached already and the output filehandle is
1012 set to non-blocking operations). 1755 set to non-blocking operations).
1013 1756
1014 Returns the number of bytes copied, or -1 on error. 1757 Returns the number of bytes copied, or -1 on error.
1015 1758
1016 IO::AIO::fadvise $fh, $offset, $len, $advice 1759 IO::AIO::fadvise $fh, $offset, $len, $advice
1017 Simply calls the "posix_fadvise" function (see it's manpage for 1760 Simply calls the "posix_fadvise" function (see its manpage for
1018 details). The following advice constants are avaiable: 1761 details). The following advice constants are available:
1019 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1762 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1763 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1764 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022 1765
1023 On systems that do not implement "posix_fadvise", this function 1766 On systems that do not implement "posix_fadvise", this function
1024 returns ENOSYS, otherwise the return value of "posix_fadvise". 1767 returns ENOSYS, otherwise the return value of "posix_fadvise".
1025 1768
1769 IO::AIO::madvise $scalar, $offset, $len, $advice
1770 Simply calls the "posix_madvise" function (see its manpage for
1771 details). The following advice constants are available:
1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1774 "IO::AIO::MADV_DONTNEED".
1775
1776 If $offset is negative, counts from the end. If $length is negative,
1777 the remaining length of the $scalar is used. If possible, $length
1778 will be reduced to fit into the $scalar.
1779
1780 On systems that do not implement "posix_madvise", this function
1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1782
1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1785 $scalar (see its manpage for details). The following protect
1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1787 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1788
1789 If $offset is negative, counts from the end. If $length is negative,
1790 the remaining length of the $scalar is used. If possible, $length
1791 will be reduced to fit into the $scalar.
1792
1793 On systems that do not implement "mprotect", this function returns
1794 ENOSYS, otherwise the return value of "mprotect".
1795
1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1797 Memory-maps a file (or anonymous memory range) and attaches it to
1798 the given $scalar, which will act like a string scalar. Returns true
1799 on success, and false otherwise.
1800
1801 The scalar must exist, but its contents do not matter - this means
1802 you cannot use a nonexistant array or hash element. When in doubt,
1803 "undef" the scalar first.
1804
1805 The only operations allowed on the mmapped scalar are
1806 "substr"/"vec", which don't change the string length, and most
1807 read-only operations such as copying it or searching it with regexes
1808 and so on.
1809
1810 Anything else is unsafe and will, at best, result in memory leaks.
1811
1812 The memory map associated with the $scalar is automatically removed
1813 when the $scalar is undef'd or destroyed, or when the
1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1815
1816 This calls the "mmap"(2) function internally. See your system's
1817 manual page for details on the $length, $prot and $flags parameters.
1818
1819 The $length must be larger than zero and smaller than the actual
1820 filesize.
1821
1822 $prot is a combination of "IO::AIO::PROT_NONE",
1823 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1824 "IO::AIO::PROT_WRITE",
1825
1826 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1827 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1828 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1829 "MAP_ANON" if your system only provides this constant),
1830 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1831 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1832 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1833 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1834 "IO::AIO::MAP_STACK".
1835
1836 If $fh is "undef", then a file descriptor of -1 is passed.
1837
1838 $offset is the offset from the start of the file - it generally must
1839 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1840
1841 Example:
1842
1843 use Digest::MD5;
1844 use IO::AIO;
1845
1846 open my $fh, "<verybigfile"
1847 or die "$!";
1848
1849 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1850 or die "verybigfile: $!";
1851
1852 my $fast_md5 = md5 $data;
1853
1854 IO::AIO::munmap $scalar
1855 Removes a previous mmap and undefines the $scalar.
1856
1857 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1858 $new_address = 0]
1859 Calls the Linux-specific mremap(2) system call. The $scalar must
1860 have been mapped by "IO::AIO::mmap", and $flags must currently
1861 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1862
1863 Returns true if successful, and false otherwise. If the underlying
1864 mmapped region has changed address, then the true value has the
1865 numerical value 1, otherwise it has the numerical value 0:
1866
1867 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1868 or die "mremap: $!";
1869
1870 if ($success*1) {
1871 warn "scalar has chanegd address in memory\n";
1872 }
1873
1874 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1875 implemented, but not supported and might go away in a future
1876 version.
1877
1878 On systems where this call is not supported or is not emulated, this
1879 call returns falls and sets $! to "ENOSYS".
1880
1881 IO::AIO::mlockall $flags
1882 Calls the "eio_mlockall_sync" function, which is like
1883 "aio_mlockall", but is blocking.
1884
1885 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1886 Calls the "munlock" function, undoing the effects of a previous
1887 "aio_mlock" call (see its description for details).
1888
1889 IO::AIO::munlockall
1890 Calls the "munlockall" function.
1891
1892 On systems that do not implement "munlockall", this function returns
1893 ENOSYS, otherwise the return value of "munlockall".
1894
1895 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1896 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1897 socket and return the new file handle on success, or sets $! and
1898 returns "undef" on error.
1899
1900 The remote name of the new socket will be stored in $sockaddr, which
1901 will be extended to allow for at least $sockaddr_maxlen octets. If
1902 the socket name does not fit into $sockaddr_maxlen octets, this is
1903 signaled by returning a longer string in $sockaddr, which might or
1904 might not be truncated.
1905
1906 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1907 $sockaddr_maxlen.
1908
1909 The main reasons to use this syscall rather than portable accept(2)
1910 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1911 and you can accept name-less sockets by specifying 0 for
1912 $sockaddr_maxlen, which is sadly not possible with perl's interface
1913 to "accept".
1914
1915 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1916 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1917 $w_off are "undef", then "NULL" is passed for these, otherwise they
1918 should be the file offset.
1919
1920 $r_fh and $w_fh should not refer to the same file, as splice might
1921 silently corrupt the data in this case.
1922
1923 The following symbol flag values are available:
1924 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1925 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1926
1927 See the splice(2) manpage for details.
1928
1929 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1930 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1931 description for "IO::AIO::splice" above for details.
1932
1933 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1934 Attempts to query or change the pipe buffer size. Obviously works
1935 only on pipes, and currently works only on GNU/Linux systems, and
1936 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1937 influence pipe buffer size on other systems, drop me a note.
1938
1939 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1940 This is a direct interface to the Linux pipe2(2) system call. If
1941 $flags is missing or 0, then this should be the same as a call to
1942 perl's built-in "pipe" function and create a new pipe, and works on
1943 systems that lack the pipe2 syscall. On win32, this case invokes
1944 "_pipe (..., 4096, O_BINARY)".
1945
1946 If $flags is non-zero, it tries to invoke the pipe2 system call with
1947 the given flags (Linux 2.6.27, glibc 2.9).
1948
1949 On success, the read and write file handles are returned.
1950
1951 On error, nothing will be returned. If the pipe2 syscall is missing
1952 and $flags is non-zero, fails with "ENOSYS".
1953
1954 Please refer to pipe2(2) for more info on the $flags, but at the
1955 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1956 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1957 supported.
1958
1959 Example: create a pipe race-free w.r.t. threads and fork:
1960
1961 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1962 or die "pipe2: $!\n";
1963
1964 $fh = IO::AIO::memfd_create $pathname[, $flags]
1965 This is a direct interface to the Linux memfd_create(2) system call.
1966 The (unhelpful) default for $flags is 0, but your default should be
1967 "IO::AIO::MFD_CLOEXEC".
1968
1969 On success, the new memfd filehandle is returned, otherwise returns
1970 "undef". If the memfd_create syscall is missing, fails with
1971 "ENOSYS".
1972
1973 Please refer to memfd_create(2) for more info on this call.
1974
1975 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1976 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1977
1978 Example: create a new memfd.
1979
1980 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1981 or die "memfd_create: $!\n";
1982
1983 $fh = IO::AIO::pidfd_open $pid[, $flags]
1984 This is an interface to the Linux pidfd_open(2) system call. The
1985 default for $flags is 0.
1986
1987 On success, a new pidfd filehandle is returned (that is already set
1988 to close-on-exec), otherwise returns "undef". If the syscall is
1989 missing, fails with "ENOSYS".
1990
1991 Example: open pid 6341 as pidfd.
1992
1993 my $fh = IO::AIO::pidfd_open 6341
1994 or die "pidfd_open: $!\n";
1995
1996 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
1997 $flags]]
1998 This is an interface to the Linux pidfd_send_signal system call. The
1999 default for $siginfo is "undef" and the default for $flags is 0.
2000
2001 Returns the system call status. If the syscall is missing, fails
2002 with "ENOSYS".
2003
2004 When specified, $siginfo must be a reference to a hash with one or
2005 more of the following members:
2006
2007 code - the "si_code" member
2008 pid - the "si_pid" member
2009 uid - the "si_uid" member
2010 value_int - the "si_value.sival_int" member
2011 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2012
2013 Example: send a SIGKILL to the specified process.
2014
2015 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2016 and die "pidfd_send_signal: $!\n";
2017
2018 Example: send a SIGKILL to the specified process with extra data.
2019
2020 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2021 and die "pidfd_send_signal: $!\n";
2022
2023 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2024 This is an interface to the Linux pidfd_getfd system call. The
2025 default for $flags is 0.
2026
2027 On success, returns a dup'ed copy of the target file descriptor
2028 (specified as an integer) returned (that is already set to
2029 close-on-exec), otherwise returns "undef". If the syscall is
2030 missing, fails with "ENOSYS".
2031
2032 Example: get a copy of standard error of another process and print
2033 soemthing to it.
2034
2035 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2036 or die "pidfd_getfd: $!\n";
2037 print $errfh "stderr\n";
2038
2039 $fh = IO::AIO::eventfd [$initval, [$flags]]
2040 This is a direct interface to the Linux eventfd(2) system call. The
2041 (unhelpful) defaults for $initval and $flags are 0 for both.
2042
2043 On success, the new eventfd filehandle is returned, otherwise
2044 returns "undef". If the eventfd syscall is missing, fails with
2045 "ENOSYS".
2046
2047 Please refer to eventfd(2) for more info on this call.
2048
2049 The following symbol flag values are available:
2050 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2051 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2052
2053 Example: create a new eventfd filehandle:
2054
2055 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2056 or die "eventfd: $!\n";
2057
2058 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2059 This is a direct interface to the Linux timerfd_create(2) system
2060 call. The (unhelpful) default for $flags is 0, but your default
2061 should be "IO::AIO::TFD_CLOEXEC".
2062
2063 On success, the new timerfd filehandle is returned, otherwise
2064 returns "undef". If the timerfd_create syscall is missing, fails
2065 with "ENOSYS".
2066
2067 Please refer to timerfd_create(2) for more info on this call.
2068
2069 The following $clockid values are available:
2070 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2071 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2072 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2073 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2074
2075 The following $flags values are available (Linux 2.6.27):
2076 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2077
2078 Example: create a new timerfd and set it to one-second repeated
2079 alarms, then wait for two alarms:
2080
2081 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2082 or die "timerfd_create: $!\n";
2083
2084 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2085 or die "timerfd_settime: $!\n";
2086
2087 for (1..2) {
2088 8 == sysread $fh, my $buf, 8
2089 or die "timerfd read failure\n";
2090
2091 printf "number of expirations (likely 1): %d\n",
2092 unpack "Q", $buf;
2093 }
2094
2095 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2096 $new_interval, $nbw_value
2097 This is a direct interface to the Linux timerfd_settime(2) system
2098 call. Please refer to its manpage for more info on this call.
2099
2100 The new itimerspec is specified using two (possibly fractional)
2101 second values, $new_interval and $new_value).
2102
2103 On success, the current interval and value are returned (as per
2104 "timerfd_gettime"). On failure, the empty list is returned.
2105
2106 The following $flags values are available:
2107 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2108
2109 See "IO::AIO::timerfd_create" for a full example.
2110
2111 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2112 This is a direct interface to the Linux timerfd_gettime(2) system
2113 call. Please refer to its manpage for more info on this call.
2114
2115 On success, returns the current values of interval and value for the
2116 given timerfd (as potentially fractional second values). On failure,
2117 the empty list is returned.
2118
2119EVENT LOOP INTEGRATION
2120 It is recommended to use AnyEvent::AIO to integrate IO::AIO
2121 automatically into many event loops:
2122
2123 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
2124 use AnyEvent::AIO;
2125
2126 You can also integrate IO::AIO manually into many event loops, here are
2127 some examples of how to do this:
2128
2129 # EV integration
2130 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
2131
2132 # Event integration
2133 Event->io (fd => IO::AIO::poll_fileno,
2134 poll => 'r',
2135 cb => \&IO::AIO::poll_cb);
2136
2137 # Glib/Gtk2 integration
2138 add_watch Glib::IO IO::AIO::poll_fileno,
2139 in => sub { IO::AIO::poll_cb; 1 };
2140
2141 # Tk integration
2142 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
2143 readable => \&IO::AIO::poll_cb);
2144
2145 # Danga::Socket integration
2146 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
2147 \&IO::AIO::poll_cb);
2148
1026 FORK BEHAVIOUR 2149 FORK BEHAVIOUR
1027 This module should do "the right thing" when the process using it forks: 2150 Usage of pthreads in a program changes the semantics of fork
2151 considerably. Specifically, only async-safe functions can be called
2152 after fork. Perl doesn't know about this, so in general, you cannot call
2153 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2154 uses pthreads, so this applies, but many other extensions and (for
2155 inexplicable reasons) perl itself often is linked against pthreads, so
2156 this limitation applies to quite a lot of perls.
1028 2157
1029 Before the fork, IO::AIO enters a quiescent state where no requests can 2158 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 2159 IO::AIO only works in the process that loaded it. Forking is fully
1031 fork the parent simply leaves the quiescent state and continues 2160 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 2161
1037 In short: the parent will, after a short pause, continue as if fork had 2162 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 2163 You could also try to call the IO::AIO::reinit function in the child:
1039 used yet. 2164
2165 IO::AIO::reinit
2166 Abandons all current requests and I/O threads and simply
2167 reinitialises all data structures. This is not an operation
2168 supported by any standards, but happens to work on GNU/Linux and
2169 some newer BSD systems.
2170
2171 The only reasonable use for this function is to call it after
2172 forking, if "IO::AIO" was used in the parent. Calling it while
2173 IO::AIO is active in the process will result in undefined behaviour.
2174 Calling it at any time will also result in any undefined (by POSIX)
2175 behaviour.
2176
2177 LINUX-SPECIFIC CALLS
2178 When a call is documented as "linux-specific" then this means it
2179 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2180 availability and compatibility of such calls regardless of the platform
2181 it is compiled on, so platforms such as FreeBSD which often implement
2182 these calls will work. When in doubt, call them and see if they fail wth
2183 "ENOSYS".
1040 2184
1041 MEMORY USAGE 2185 MEMORY USAGE
1042 Per-request usage: 2186 Per-request usage:
1043 2187
1044 Each aio request uses - depending on your architecture - around 100-200 2188 Each aio request uses - depending on your architecture - around 100-200
… …
1055 In the execution phase, some aio requests require more memory for 2199 In the execution phase, some aio requests require more memory for
1056 temporary buffers, and each thread requires a stack and other data 2200 temporary buffers, and each thread requires a stack and other data
1057 structures (usually around 16k-128k, depending on the OS). 2201 structures (usually around 16k-128k, depending on the OS).
1058 2202
1059KNOWN BUGS 2203KNOWN BUGS
1060 Known bugs will be fixed in the next release. 2204 Known bugs will be fixed in the next release :)
2205
2206KNOWN ISSUES
2207 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2208 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2209 non-created hash slots or other scalars I didn't think of. It's best to
2210 avoid such and either use scalar variables or making sure that the
2211 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2212
2213 I am not sure anything can be done about this, so this is considered a
2214 known issue, rather than a bug.
1061 2215
1062SEE ALSO 2216SEE ALSO
1063 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2217 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1064 more natural syntax. 2218 more natural syntax and IO::FDPass for file descriptor passing.
1065 2219
1066AUTHOR 2220AUTHOR
1067 Marc Lehmann <schmorp@schmorp.de> 2221 Marc Lehmann <schmorp@schmorp.de>
1068 http://home.schmorp.de/ 2222 http://home.schmorp.de/
1069 2223

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