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Revision 1.67 by root, Tue Jul 27 07:58:38 2021 UTC

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", IO::AIO::O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
… …
55 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
56 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
57 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
58 using threads anyway. 58 using threads anyway.
59 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
60 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,
61 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
62 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
63 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
64 68
65 EXAMPLE 69 EXAMPLE
66 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
67 asynchronously: 71 asynchronously:
68 72
69 use Fcntl;
70 use EV; 73 use EV;
71 use IO::AIO; 74 use IO::AIO;
72 75
73 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
74 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;
… …
91 94
92 # file contents now in $contents 95 # file contents now in $contents
93 print $contents; 96 print $contents;
94 97
95 # exit event loop and program 98 # exit event loop and program
96 EV::unloop; 99 EV::break;
97 }; 100 };
98 }; 101 };
99 102
100 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 104 # check for sockets etc. etc.
102 105
103 # process events as long as there are some: 106 # process events as long as there are some:
104 EV::loop; 107 EV::run;
105 108
106REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
107 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
108 not directly visible to Perl. 111 not directly visible to Perl.
109 112
… …
146 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
148 151
149FUNCTIONS 152FUNCTIONS
150 QUICK OVERVIEW 153 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 154 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 155 reference. See the following sections for function-by-function
153 documentation. 156 documentation.
154 157
158 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 159 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 160 aio_close $fh, $callback->($status)
161 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 162 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 163 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 164 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 165 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 166 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 167 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 168 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
171 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 172 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status) 173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168 aio_unlink $pathname, $callback->($status) 175 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 176 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 177 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 178 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 179 aio_readlink $pathname, $callback->($link)
180 aio_realpath $pathname, $callback->($path)
173 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 188 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180 aio_load $path, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status) 193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
185 aio_sync $callback->($status) 196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
186 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...) 206 aio_group $callback->(...)
195 aio_nop $callback->() 207 aio_nop $callback->()
… …
209 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
210 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
211 IO::AIO::nreqs 223 IO::AIO::nreqs
212 IO::AIO::nready 224 IO::AIO::nready
213 IO::AIO::npending 225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
214 230
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count 231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice 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]
217 IO::AIO::madvise $scalar, $offset, $length, $advice 237 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect 238 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef 239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall 240 IO::AIO::munlockall
221 241
222 AIO REQUEST FUNCTIONS 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
223 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
224 with the same name (sans "aio_"). The arguments are similar or 264 with the same name (sans "aio_"). The arguments are similar or
225 identical, and they all accept an additional (and optional) $callback 265 identical, and they all accept an additional (and optional) $callback
226 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
227 called with the syscall return code (e.g. most syscalls return -1 on
228 error, unlike perl, which usually delivers "false") as its sole argument
229 after the given syscall has been executed asynchronously. 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".
230 275
231 All functions expecting a filehandle keep a copy of the filehandle 276 All functions expecting a filehandle keep a copy of the filehandle
232 internally until the request has finished. 277 internally until the request has finished.
233 278
234 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
235 further manipulation of those requests while they are in-flight. 280 further manipulation of those requests while they are in-flight.
236 281
237 The pathnames you pass to these routines *must* be absolute and encoded 282 The pathnames you pass to these routines *should* be absolute. The
238 as octets. The reason for the former is that at the time the request is 283 reason for this is that at the time the request is being executed, the
239 being executed, the current working directory could have changed. 284 current working directory could have changed. Alternatively, you can
240 Alternatively, you can make sure that you never change the current 285 make sure that you never change the current working directory anywhere
241 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.
242 290
243 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
244 pass in filenames you got from outside (command line, readdir etc.) 292 pass in filenames you got from outside (command line, readdir etc.)
245 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 293 without tinkering, b) are in your native filesystem encoding, c) use the
246 and encode your pathnames to the locale (or other) encoding in effect in 294 Encode module and encode your pathnames to the locale (or other)
247 the user environment, d) use Glib::filename_from_unicode on unicode 295 encoding in effect in the user environment, d) use
248 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
249 contents. 297 else to ensure your scalar has the correct contents.
250 298
251 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
252 handles correctly whether it is set or not. 300 handles correctly whether it is set or not.
253 301
302 AIO REQUEST FUNCTIONS
254 $prev_pri = aioreq_pri [$pri] 303 $prev_pri = aioreq_pri [$pri]
255 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
256 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.
257 306
258 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
… …
280 Similar to "aioreq_pri", but subtracts the given value from the 329 Similar to "aioreq_pri", but subtracts the given value from the
281 current priority, so the effect is cumulative. 330 current priority, so the effect is cumulative.
282 331
283 aio_open $pathname, $flags, $mode, $callback->($fh) 332 aio_open $pathname, $flags, $mode, $callback->($fh)
284 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
285 newly created filehandle for the file. 334 newly created filehandle for the file (or "undef" in case of an
335 error).
286 336
287 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,
288 above, for an explanation. 338 above, for an explanation.
289 339
290 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.
… …
306 } else { 356 } else {
307 die "open failed: $!\n"; 357 die "open failed: $!\n";
308 } 358 }
309 }; 359 };
310 360
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
311 aio_close $fh, $callback->($status) 371 aio_close $fh, $callback->($status)
312 Asynchronously close a file and call the callback with the result 372 Asynchronously close a file and call the callback with the result
313 code. 373 code.
314 374
315 Unfortunately, you can't do this to perl. Perl *insists* very 375 Unfortunately, you can't do this to perl. Perl *insists* very
… …
320 will use dup2 to overwrite the file descriptor with the write-end of 380 will use dup2 to overwrite the file descriptor with the write-end of
321 a pipe (the pipe fd will be created on demand and will be cached). 381 a pipe (the pipe fd will be created on demand and will be cached).
322 382
323 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
324 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".
325 404
326 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
327 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 406 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
328 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
329 $offset into the scalar given by $data and offset $dataoffset and 408 $offset into the scalar given by $data and offset $dataoffset and
330 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
331 error, just like the syscall). 410 -1 on error, just like the syscall).
332 411
333 "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
334 offset plus the actual number of bytes read. 413 offset plus the actual number of bytes read.
335 414
336 If $offset is undefined, then the current file descriptor offset 415 If $offset is undefined, then the current file descriptor offset
… …
358 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 437 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
359 Tries to copy $length bytes from $in_fh to $out_fh. It starts 438 Tries to copy $length bytes from $in_fh to $out_fh. It starts
360 reading at byte offset $in_offset, and starts writing at the current 439 reading at byte offset $in_offset, and starts writing at the current
361 file offset of $out_fh. Because of that, it is not safe to issue 440 file offset of $out_fh. Because of that, it is not safe to issue
362 more than one "aio_sendfile" per $out_fh, as they will interfere 441 more than one "aio_sendfile" per $out_fh, as they will interfere
363 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.
364 444
365 Please note that "aio_sendfile" can read more bytes from $in_fh than 445 Please note that "aio_sendfile" can read more bytes from $in_fh than
366 are written, and there is no way to find out how many bytes have 446 are written, and there is no way to find out how many more bytes
367 been read from "aio_sendfile" alone, as "aio_sendfile" only provides 447 have been read from "aio_sendfile" alone, as "aio_sendfile" only
368 the number of bytes written to $out_fh. Only if the result value 448 provides the number of bytes written to $out_fh. Only if the result
369 equals $length one can assume that $length bytes have been read. 449 value equals $length one can assume that $length bytes have been
450 read.
370 451
371 Unlike with other "aio_" functions, it makes a lot of sense to use 452 Unlike with other "aio_" functions, it makes a lot of sense to use
372 "aio_sendfile" on non-blocking sockets, as long as one end 453 "aio_sendfile" on non-blocking sockets, as long as one end
373 (typically the $in_fh) is a file - the file I/O will then be 454 (typically the $in_fh) is a file - the file I/O will then be
374 asynchronous, while the socket I/O will be non-blocking. Note, 455 asynchronous, while the socket I/O will be non-blocking. Note,
375 however, that you can run into a trap where "aio_sendfile" reads 456 however, that you can run into a trap where "aio_sendfile" reads
376 some data with readahead, then fails to write all data, and when the 457 some data with readahead, then fails to write all data, and when the
377 socket is ready the next time, the data in the cache is already 458 socket is ready the next time, the data in the cache is already
378 lost, forcing "aio_sendfile" to again hit the disk. Explicit 459 lost, forcing "aio_sendfile" to again hit the disk. Explicit
379 "aio_read" + "aio_write" let's you control resource usage much 460 "aio_read" + "aio_write" let's you better control resource usage.
380 better.
381 461
382 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
383 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
384 to a socket, and $in_fh should refer to an mmap'able file. 464 to a socket, and $in_fh should refer to an mmap'able file.
385 465
386 If a native sendfile cannot be found or it fails with "ENOSYS", 466 If a native sendfile cannot be found or it fails with "ENOSYS",
387 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", 467 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
388 it will be emulated, so you can call "aio_sendfile" on any type of 468 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
389 filehandle regardless of the limitations of the operating system. 469 any type of filehandle regardless of the limitations of the
470 operating system.
471
472 As native sendfile syscalls (as practically any non-POSIX interface
473 hacked together in a hurry to improve benchmark numbers) tend to be
474 rather buggy on many systems, this implementation tries to work
475 around some known bugs in Linux and FreeBSD kernels (probably
476 others, too), but that might fail, so you really really should check
477 the return value of "aio_sendfile" - fewer bytes than expected might
478 have been transferred.
390 479
391 aio_readahead $fh,$offset,$length, $callback->($retval) 480 aio_readahead $fh,$offset,$length, $callback->($retval)
392 "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
393 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
394 $offset argument specifies the starting point from which data is to 483 $offset argument specifies the starting point from which data is to
… …
397 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
398 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
399 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
400 is left unchanged. 489 is left unchanged.
401 490
402 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
403 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
404 similar effect. 493 similar effect.
405 494
406 aio_stat $fh_or_path, $callback->($status) 495 aio_stat $fh_or_path, $callback->($status)
407 aio_lstat $fh, $callback->($status) 496 aio_lstat $fh, $callback->($status)
408 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.
409 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
410 using "stat _" or "-s _" etc... 499 available using "stat _" or "-s _" and other tests (with the
500 exception of "-B" and "-T").
411 501
412 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,
413 above, for an explanation. 503 above, for an explanation.
414 504
415 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
… …
423 back on traditional behaviour). 513 back on traditional behaviour).
424 514
425 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 515 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
426 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 516 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
427 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 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".
428 521
429 Example: Print the length of /etc/passwd: 522 Example: Print the length of /etc/passwd:
430 523
431 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
432 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
… …
479 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 572 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
480 Works like perl's "utime" function (including the special case of 573 Works like perl's "utime" function (including the special case of
481 $atime and $mtime being undef). Fractional times are supported if 574 $atime and $mtime being undef). Fractional times are supported if
482 the underlying syscalls support them. 575 the underlying syscalls support them.
483 576
484 When called with a pathname, uses utimes(2) if available, otherwise 577 When called with a pathname, uses utimensat(2) or utimes(2) if
485 utime(2). If called on a file descriptor, uses futimes(2) if 578 available, otherwise utime(2). If called on a file descriptor, uses
486 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.
487 581
488 Examples: 582 Examples:
489 583
490 # set atime and mtime to current time (basically touch(1)): 584 # set atime and mtime to current time (basically touch(1)):
491 aio_utime "path", undef, undef; 585 aio_utime "path", undef, undef;
… …
505 aio_chown "path", 0, undef; 599 aio_chown "path", 0, undef;
506 600
507 aio_truncate $fh_or_path, $offset, $callback->($status) 601 aio_truncate $fh_or_path, $offset, $callback->($status)
508 Works like truncate(2) or ftruncate(2). 602 Works like truncate(2) or ftruncate(2).
509 603
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
510 aio_chmod $fh_or_path, $mode, $callback->($status) 625 aio_chmod $fh_or_path, $mode, $callback->($status)
511 Works like perl's "chmod" function. 626 Works like perl's "chmod" function.
512 627
513 aio_unlink $pathname, $callback->($status) 628 aio_unlink $pathname, $callback->($status)
514 Asynchronously unlink (delete) a file and call the callback with the 629 Asynchronously unlink (delete) a file and call the callback with the
515 result code. 630 result code.
516 631
517 aio_mknod $path, $mode, $dev, $callback->($status) 632 aio_mknod $pathname, $mode, $dev, $callback->($status)
518 [EXPERIMENTAL] 633 [EXPERIMENTAL]
519 634
520 Asynchronously create a device node (or fifo). See mknod(2). 635 Asynchronously create a device node (or fifo). See mknod(2).
521 636
522 The only (POSIX-) portable way of calling this function is: 637 The only (POSIX-) portable way of calling this function is:
523 638
524 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 639 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
525 640
526 See "aio_stat" for info about some potentially helpful extra 641 See "aio_stat" for info about some potentially helpful extra
527 constants and functions. 642 constants and functions.
528 643
529 aio_link $srcpath, $dstpath, $callback->($status) 644 aio_link $srcpath, $dstpath, $callback->($status)
… …
533 aio_symlink $srcpath, $dstpath, $callback->($status) 648 aio_symlink $srcpath, $dstpath, $callback->($status)
534 Asynchronously create a new symbolic link to the existing object at 649 Asynchronously create a new symbolic link to the existing object at
535 $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
536 code. 651 code.
537 652
538 aio_readlink $path, $callback->($link) 653 aio_readlink $pathname, $callback->($link)
539 Asynchronously read the symlink specified by $path and pass it to 654 Asynchronously read the symlink specified by $path and pass it to
540 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
541 the callback. 656 the callback.
542 657
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
543 aio_rename $srcpath, $dstpath, $callback->($status) 666 aio_rename $srcpath, $dstpath, $callback->($status)
544 Asynchronously rename the object at $srcpath to $dstpath, just as 667 Asynchronously rename the object at $srcpath to $dstpath, just as
545 rename(2) and call the callback with the result code. 668 rename(2) and call the callback with the result code.
669
670 On systems that support the AIO::WD working directory abstraction
671 natively, the case "[$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".
546 688
547 aio_mkdir $pathname, $mode, $callback->($status) 689 aio_mkdir $pathname, $mode, $callback->($status)
548 Asynchronously mkdir (create) a directory and call the callback with 690 Asynchronously mkdir (create) a directory and call the callback with
549 the result code. $mode will be modified by the umask at the time the 691 the result code. $mode will be modified by the umask at the time the
550 request is executed, so do not change your umask. 692 request is executed, so do not change your umask.
551 693
552 aio_rmdir $pathname, $callback->($status) 694 aio_rmdir $pathname, $callback->($status)
553 Asynchronously rmdir (delete) a directory and call the callback with 695 Asynchronously rmdir (delete) a directory and call the callback with
554 the result code. 696 the result code.
555 697
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
556 aio_readdir $pathname, $callback->($entries) 702 aio_readdir $pathname, $callback->($entries)
557 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
558 entire directory (i.e. opendir + readdir + closedir). The entries 704 entire directory (i.e. opendir + readdir + closedir). The entries
559 will not be sorted, and will NOT include the "." and ".." entries. 705 will not be sorted, and will NOT include the "." and ".." entries.
560 706
561 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
562 an array-ref with the filenames. 708 an array-ref with the filenames.
563 709
564 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 710 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
565 Quite similar to "aio_readdir", but the $flags argument allows to 711 Quite similar to "aio_readdir", but the $flags argument allows one
566 tune behaviour and output format. In case of an error, $entries will 712 to tune behaviour and output format. In case of an error, $entries
567 be "undef". 713 will be "undef".
568 714
569 The flags are a combination of the following constants, ORed 715 The flags are a combination of the following constants, ORed
570 together (the flags will also be passed to the callback, possibly 716 together (the flags will also be passed to the callback, possibly
571 modified): 717 modified):
572 718
573 IO::AIO::READDIR_DENTS 719 IO::AIO::READDIR_DENTS
574 When this flag is off, then the callback gets an arrayref with 720 Normally the callback gets an arrayref consisting of names only
575 of names only (as with "aio_readdir"), otherwise it gets an 721 (as with "aio_readdir"). If this flag is set, then the callback
576 arrayref with "[$name, $type, $inode]" arrayrefs, each 722 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
577 describing a single directory entry in more detail. 723 describing a single directory entry in more detail:
578 724
579 $name is the name of the entry. 725 $name is the name of the entry.
580 726
581 $type is one of the "IO::AIO::DT_xxx" constants: 727 $type is one of the "IO::AIO::DT_xxx" constants:
582 728
583 "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",
584 "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",
585 "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".
586 732
587 "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
588 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
589 reasons, the $type scalars are read-only: you can not modify 735 speed/memory reasons, the $type scalars are read-only: you must
590 them. 736 not modify them.
591 737
592 $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
593 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
594 unspecified content on systems that do not deliver the inode 740 unspecified content on systems that do not deliver the inode
595 information. 741 information.
596 742
597 IO::AIO::READDIR_DIRS_FIRST 743 IO::AIO::READDIR_DIRS_FIRST
598 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
599 order where likely directories come first. This is useful when 745 order where likely directories come first, in optimal stat
600 you need to quickly find directories, or you want to find all 746 order. This is useful when you need to quickly find directories,
601 directories while avoiding to stat() each entry. 747 or you want to find all directories while avoiding to stat()
748 each entry.
602 749
603 If the system returns type information in readdir, then this is 750 If the system returns type information in readdir, then this is
604 used to find directories directly. Otherwise, likely directories 751 used to find directories directly. Otherwise, likely directories
605 are files beginning with ".", or otherwise files with no dots, 752 are names beginning with ".", or otherwise names with no dots,
606 of which files with short names are tried first. 753 of which names with short names are tried first.
607 754
608 IO::AIO::READDIR_STAT_ORDER 755 IO::AIO::READDIR_STAT_ORDER
609 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
610 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
611 to stat() all files in the given directory, then the returned 758 to stat() most or all files in the given directory, then the
612 order will likely be fastest. 759 returned order will likely be faster.
613 760
614 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 761 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
615 specified, then the likely dirs come first, resulting in a less 762 specified, then the likely dirs come first, resulting in a less
616 optimal stat order. 763 optimal stat order for stat'ing all entries, but likely a more
764 optimal order for finding subdirectories.
617 765
618 IO::AIO::READDIR_FOUND_UNKNOWN 766 IO::AIO::READDIR_FOUND_UNKNOWN
619 This flag should not be set when calling "aio_readdirx". 767 This flag should not be set when calling "aio_readdirx".
620 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
621 $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
622 flag therefore indicates that all $type's are known, which can 770 flag therefore indicates that all $type's are known, which can
623 be used to speed up some algorithms. 771 be used to speed up some algorithms.
624 772
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
625 aio_load $path, $data, $callback->($status) 800 aio_load $pathname, $data, $callback->($status)
626 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
627 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.
628 806
629 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
630 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
631 or destination) from $srcpath to $dstpath and call the callback with 809 or destination) from $srcpath to $dstpath and call the callback with
632 a status of 0 (ok) or -1 (error, see $!). 810 a status of 0 (ok) or -1 (error, see $!).
633 811
812 Existing destination files will be truncated.
813
634 This is a composite request that creates the destination file with 814 This is a composite request that creates the destination file with
635 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
636 "aio_sendfile", followed by restoring atime, mtime, access mode and 816 "aio_sendfile", followed by restoring atime, mtime, access mode and
637 uid/gid, in that order. 817 uid/gid, in that order.
638 818
… …
647 827
648 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;
649 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"
650 and, if that is successful, unlinks the $srcpath. 830 and, if that is successful, unlinks the $srcpath.
651 831
652 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 832 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
653 Scans a directory (similar to "aio_readdir") but additionally tries 833 Scans a directory (similar to "aio_readdir") but additionally tries
654 to efficiently separate the entries of directory $path into two sets 834 to efficiently separate the entries of directory $path into two sets
655 of names, directories you can recurse into (directories), and ones 835 of names, directories you can recurse into (directories), and ones
656 you cannot recurse into (everything else, including symlinks to 836 you cannot recurse into (everything else, including symlinks to
657 directories). 837 directories).
658 838
659 "aio_scandir" is a composite request that creates of many sub 839 "aio_scandir" is a composite request that generates many sub
660 requests_ $maxreq specifies the maximum number of outstanding aio 840 requests. $maxreq specifies the maximum number of outstanding aio
661 requests that this function generates. If it is "<= 0", then a 841 requests that this function generates. If it is "<= 0", then a
662 suitable default will be chosen (currently 4). 842 suitable default will be chosen (currently 4).
663 843
664 On error, the callback is called without arguments, otherwise it 844 On error, the callback is called without arguments, otherwise it
665 receives two array-refs with path-relative entry names. 845 receives two array-refs with path-relative entry names.
… …
690 Then entries will be sorted into likely directories a non-initial 870 Then entries will be sorted into likely directories a non-initial
691 dot currently) and likely non-directories (see "aio_readdirx"). Then 871 dot currently) and likely non-directories (see "aio_readdirx"). Then
692 every entry plus an appended "/." will be "stat"'ed, likely 872 every entry plus an appended "/." will be "stat"'ed, likely
693 directories first, in order of their inode numbers. If that 873 directories first, in order of their inode numbers. If that
694 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
695 directory (which will be checked seperately). This is often faster 875 directory (which will be checked separately). This is often faster
696 than stat'ing the entry itself because filesystems might detect the 876 than stat'ing the entry itself because filesystems might detect the
697 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
698 filetype feature), even on systems that cannot return the filetype 878 filetype feature), even on systems that cannot return the filetype
699 information on readdir. 879 information on readdir.
700 880
… …
706 886
707 It will also likely work on non-POSIX filesystems with reduced 887 It will also likely work on non-POSIX filesystems with reduced
708 efficiency as those tend to return 0 or 1 as link counts, which 888 efficiency as those tend to return 0 or 1 as link counts, which
709 disables the directory counting heuristic. 889 disables the directory counting heuristic.
710 890
711 aio_rmtree $path, $callback->($status) 891 aio_rmtree $pathname, $callback->($status)
712 Delete a directory tree starting (and including) $path, return the 892 Delete a directory tree starting (and including) $path, return the
713 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
714 uses "aio_scandir" to recurse into and rmdir directories, and unlink 894 uses "aio_scandir" to recurse into and rmdir directories, and unlink
715 everything else. 895 everything else.
716 896
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
717 aio_sync $callback->($status) 948 aio_sync $callback->($status)
718 Asynchronously call sync and call the callback when finished. 949 Asynchronously call sync and call the callback when finished.
719 950
720 aio_fsync $fh, $callback->($status) 951 aio_fsync $fh, $callback->($status)
721 Asynchronously call fsync on the given filehandle and call the 952 Asynchronously call fsync on the given filehandle and call the
… …
725 Asynchronously call fdatasync on the given filehandle and call the 956 Asynchronously call fdatasync on the given filehandle and call the
726 callback with the fdatasync result code. 957 callback with the fdatasync result code.
727 958
728 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
729 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.
730 967
731 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 968 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
732 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
733 to disk (but NOT the metadata), by calling the Linux-specific 970 to disk (but NOT the metadata), by calling the Linux-specific
734 sync_file_range call. If sync_file_range is not available or it 971 sync_file_range call. If sync_file_range is not available or it
… …
738 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 975 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
739 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 976 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
740 "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
741 manpage for details. 978 manpage for details.
742 979
743 aio_pathsync $path, $callback->($status) 980 aio_pathsync $pathname, $callback->($status)
744 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
745 a composite request intended to sync directories after directory 982 a composite request intended to sync directories after directory
746 operations (E.g. rename). This might not work on all operating 983 operations (E.g. rename). This might not work on all operating
747 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
748 directory changes get written to disc. It works for anything that 985 directory changes get written to disc. It works for anything that
… …
751 Future versions of this function might fall back to other methods 988 Future versions of this function might fall back to other methods
752 when "fsync" on the directory fails (such as calling "sync"). 989 when "fsync" on the directory fails (such as calling "sync").
753 990
754 Passes 0 when everything went ok, and -1 on error. 991 Passes 0 when everything went ok, and -1 on error.
755 992
756 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 993 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
757 $callback->($status) 994 $callback->($status)
758 This is a rather advanced IO::AIO call, which only works on 995 This is a rather advanced IO::AIO call, which only works on
759 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 996 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
760 also works on data scalars managed by the Sys::Mmap or Mmap modules, 997 also works on data scalars managed by the Sys::Mmap or Mmap modules,
761 note that the scalar must only be modified in-place while an aio 998 note that the scalar must only be modified in-place while an aio
… …
763 1000
764 It calls the "msync" function of your OS, if available, with the 1001 It calls the "msync" function of your OS, if available, with the
765 memory area starting at $offset in the string and ending $length 1002 memory area starting at $offset in the string and ending $length
766 bytes later. If $length is negative, counts from the end, and if 1003 bytes later. If $length is negative, counts from the end, and if
767 $length is "undef", then it goes till the end of the string. The 1004 $length is "undef", then it goes till the end of the string. The
768 flags can be a combination of "IO::AIO::MS_ASYNC", 1005 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
769 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 1006 an optional "IO::AIO::MS_INVALIDATE".
770 1007
771 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 1008 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
772 $callback->($status) 1009 $callback->($status)
773 This is a rather advanced IO::AIO call, which works best on 1010 This is a rather advanced IO::AIO call, which works best on
774 mmap(2)ed scalars. 1011 mmap(2)ed scalars.
775 1012
776 It touches (reads or writes) all memory pages in the specified range 1013 It touches (reads or writes) all memory pages in the specified range
777 inside the scalar. All caveats and parameters are the same as for 1014 inside the scalar. All caveats and parameters are the same as for
778 "aio_msync", above, except for flags, which must be either 0 (which 1015 "aio_msync", above, except for flags, which must be either 0 (which
779 reads all pages and ensures they are instantiated) or 1016 reads all pages and ensures they are instantiated) or
780 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 1017 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
781 and writing an octet from it, which dirties the page). 1018 and writing an octet from it, which dirties the page).
782 1019
783 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1020 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
784 This is a rather advanced IO::AIO call, which works best on 1021 This is a rather advanced IO::AIO call, which works best on
785 mmap(2)ed scalars. 1022 mmap(2)ed scalars.
… …
805 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1042 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
806 aio_mlock $data; # mlock in background 1043 aio_mlock $data; # mlock in background
807 1044
808 aio_mlockall $flags, $callback->($status) 1045 aio_mlockall $flags, $callback->($status)
809 Calls the "mlockall" function with the given $flags (a combination 1046 Calls the "mlockall" function with the given $flags (a combination
810 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). 1047 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1048 "IO::AIO::MCL_ONFAULT").
811 1049
812 On systems that do not implement "mlockall", this function returns 1050 On systems that do not implement "mlockall", this function returns
813 -1 and sets errno to "ENOSYS". 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".
814 1054
815 Note that the corresponding "munlockall" is synchronous and is 1055 Note that the corresponding "munlockall" is synchronous and is
816 documented under "MISCELLANEOUS FUNCTIONS". 1056 documented under "MISCELLANEOUS FUNCTIONS".
817 1057
818 Example: asynchronously lock all current and future pages into 1058 Example: asynchronously lock all current and future pages into
819 memory. 1059 memory.
820 1060
821 aio_mlockall IO::AIO::MCL_FUTURE; 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".
822 1110
823 aio_group $callback->(...) 1111 aio_group $callback->(...)
824 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
825 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
826 to bundle many requests into a single, composite, request with a 1114 to bundle many requests into a single, composite, request with a
… …
860 While it is theoretically handy to have simple I/O scheduling 1148 While it is theoretically handy to have simple I/O scheduling
861 requests like sleep and file handle readable/writable, the overhead 1149 requests like sleep and file handle readable/writable, the overhead
862 this creates is immense (it blocks a thread for a long time) so do 1150 this creates is immense (it blocks a thread for a long time) so do
863 not use this function except to put your application under 1151 not use this function except to put your application under
864 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.
865 1271
866 IO::AIO::REQ CLASS 1272 IO::AIO::REQ CLASS
867 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
868 called in non-void context. 1274 called in non-void context.
869 1275
… …
969 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
970 attached generator that generates requests if idle. The idea behind 1376 attached generator that generates requests if idle. The idea behind
971 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
972 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
973 long time. For example, "aio_scandir" might generate hundreds of 1379 long time. For example, "aio_scandir" might generate hundreds of
974 thousands "aio_stat" requests, delaying any later requests for a 1380 thousands of "aio_stat" requests, delaying any later requests for a
975 long time. 1381 long time.
976 1382
977 To avoid this, and allow incremental generation of requests, you can 1383 To avoid this, and allow incremental generation of requests, you can
978 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
979 requests. The feed callback will be called whenever there are few 1385 requests. The feed callback will be called whenever there are few
… …
1021 results. 1427 results.
1022 1428
1023 See "poll_cb" for an example. 1429 See "poll_cb" for an example.
1024 1430
1025 IO::AIO::poll_cb 1431 IO::AIO::poll_cb
1026 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
1027 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
1028 it returned earlier for whatever reason. Returns immediately when no 1434 to call this "regularly" to finish outstanding requests.
1029 events are outstanding. The amount of events processed depends on
1030 the settings of "IO::AIO::max_poll_req" and
1031 "IO::AIO::max_poll_time".
1032 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
1033 If not all requests were processed for whatever reason, the 1442 If not all requests were processed for whatever reason, the poll
1034 filehandle will still be ready when "poll_cb" returns, so normally 1443 file descriptor will still be ready when "poll_cb" returns, so
1035 you don't have to do anything special to have it called later. 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.
1036 1453
1037 Example: Install an Event watcher that automatically calls 1454 Example: Install an Event watcher that automatically calls
1038 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
1039 the SYNOPSIS section, at the top of this document): 1456 the SYNOPSIS section, at the top of this document):
1040 1457
1041 Event->io (fd => IO::AIO::poll_fileno, 1458 Event->io (fd => IO::AIO::poll_fileno,
1042 poll => 'r', async => 1, 1459 poll => 'r', async => 1,
1043 cb => \&IO::AIO::poll_cb); 1460 cb => \&IO::AIO::poll_cb);
1044 1461
1045 IO::AIO::poll_wait 1462 IO::AIO::poll_wait
1046 If there are any outstanding requests and none of them in the result 1463 Wait until either at least one request is in the result phase or no
1047 phase, wait till the result filehandle becomes ready for reading 1464 requests are outstanding anymore.
1048 (simply does a "select" on the filehandle. This is useful if you 1465
1049 want to synchronously wait for some requests to finish). 1466 This is useful if you want to synchronously wait for some requests
1467 to become ready, without actually handling them.
1050 1468
1051 See "nreqs" for an example. 1469 See "nreqs" for an example.
1052 1470
1053 IO::AIO::poll 1471 IO::AIO::poll
1054 Waits until some requests have been handled. 1472 Waits until some requests have been handled.
… …
1063 1481
1064 Strictly equivalent to: 1482 Strictly equivalent to:
1065 1483
1066 IO::AIO::poll_wait, IO::AIO::poll_cb 1484 IO::AIO::poll_wait, IO::AIO::poll_cb
1067 while IO::AIO::nreqs; 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
1068 1497
1069 IO::AIO::max_poll_reqs $nreqs 1498 IO::AIO::max_poll_reqs $nreqs
1070 IO::AIO::max_poll_time $seconds 1499 IO::AIO::max_poll_time $seconds
1071 These set the maximum number of requests (default 0, meaning 1500 These set the maximum number of requests (default 0, meaning
1072 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
… …
1153 IO::AIO::idle_timeout $seconds 1582 IO::AIO::idle_timeout $seconds
1154 Sets the minimum idle timeout (default 10) after which worker 1583 Sets the minimum idle timeout (default 10) after which worker
1155 threads are allowed to exit. SEe "IO::AIO::max_idle". 1584 threads are allowed to exit. SEe "IO::AIO::max_idle".
1156 1585
1157 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
1158 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
1159 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
1160 inexact: Better use an "aio_group" together with a feed callback. 1598 inexact: Better use an "aio_group" together with a feed callback.
1161 1599
1162 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
1163 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:
1164 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
1165 function will block until the limit is no longer exceeded.
1166 1602
1167 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
1168 the number of outstanding requests. 1619 no practical limit on the number of outstanding requests.
1169
1170 You can still queue as many requests as you want. Therefore,
1171 "max_outstanding" is mainly useful in simple scripts (with low
1172 values) or as a stop gap to shield against fatal memory overflow
1173 (with large values).
1174 1620
1175 STATISTICAL INFORMATION 1621 STATISTICAL INFORMATION
1176 IO::AIO::nreqs 1622 IO::AIO::nreqs
1177 Returns the number of requests currently in the ready, execute or 1623 Returns the number of requests currently in the ready, execute or
1178 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
… …
1189 1635
1190 IO::AIO::npending 1636 IO::AIO::npending
1191 Returns the number of requests currently in the pending state 1637 Returns the number of requests currently in the pending state
1192 (executed, but not yet processed by poll_cb). 1638 (executed, but not yet processed by poll_cb).
1193 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
1194 MISCELLANEOUS FUNCTIONS 1725 MISCELLANEOUS FUNCTIONS
1195 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
1196 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.
1197 1750
1198 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1199 Calls the "eio_sendfile_sync" function, which is like 1752 Calls the "eio_sendfile_sync" function, which is like
1200 "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
1201 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
… …
1203 1756
1204 Returns the number of bytes copied, or -1 on error. 1757 Returns the number of bytes copied, or -1 on error.
1205 1758
1206 IO::AIO::fadvise $fh, $offset, $len, $advice 1759 IO::AIO::fadvise $fh, $offset, $len, $advice
1207 Simply calls the "posix_fadvise" function (see its manpage for 1760 Simply calls the "posix_fadvise" function (see its manpage for
1208 details). The following advice constants are avaiable: 1761 details). The following advice constants are available:
1209 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1762 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1210 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1763 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1211 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1764 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1212 1765
1213 On systems that do not implement "posix_fadvise", this function 1766 On systems that do not implement "posix_fadvise", this function
1214 returns ENOSYS, otherwise the return value of "posix_fadvise". 1767 returns ENOSYS, otherwise the return value of "posix_fadvise".
1215 1768
1216 IO::AIO::madvise $scalar, $offset, $len, $advice 1769 IO::AIO::madvise $scalar, $offset, $len, $advice
1217 Simply calls the "posix_madvise" function (see its manpage for 1770 Simply calls the "posix_madvise" function (see its manpage for
1218 details). The following advice constants are avaiable: 1771 details). The following advice constants are available:
1219 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1220 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1221 "IO::AIO::MADV_DONTNEED". 1774 "IO::AIO::MADV_DONTNEED".
1222 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
1223 On systems that do not implement "posix_madvise", this function 1780 On systems that do not implement "posix_madvise", this function
1224 returns ENOSYS, otherwise the return value of "posix_madvise". 1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1225 1782
1226 IO::AIO::mprotect $scalar, $offset, $len, $protect 1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1227 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1228 $scalar (see its manpage for details). The following protect 1785 $scalar (see its manpage for details). The following protect
1229 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1230 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 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.
1231 1792
1232 On systems that do not implement "mprotect", this function returns 1793 On systems that do not implement "mprotect", this function returns
1233 ENOSYS, otherwise the return value of "mprotect". 1794 ENOSYS, otherwise the return value of "mprotect".
1234 1795
1235 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1236 Memory-maps a file (or anonymous memory range) and attaches it to 1797 Memory-maps a file (or anonymous memory range) and attaches it to
1237 the given $scalar, which will act like a string scalar. 1798 the given $scalar, which will act like a string scalar. Returns true
1799 on success, and false otherwise.
1238 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
1239 The only operations allowed on the scalar are "substr"/"vec" that 1805 The only operations allowed on the mmapped scalar are
1240 don't change the string length, and most read-only operations such 1806 "substr"/"vec", which don't change the string length, and most
1241 as copying it or searching it with regexes and so on. 1807 read-only operations such as copying it or searching it with regexes
1808 and so on.
1242 1809
1243 Anything else is unsafe and will, at best, result in memory leaks. 1810 Anything else is unsafe and will, at best, result in memory leaks.
1244 1811
1245 The memory map associated with the $scalar is automatically removed 1812 The memory map associated with the $scalar is automatically removed
1246 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1813 when the $scalar is undef'd or destroyed, or when the
1247 "IO::AIO::munmap" functions are called. 1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1248 1815
1249 This calls the "mmap"(2) function internally. See your system's 1816 This calls the "mmap"(2) function internally. See your system's
1250 manual page for details on the $length, $prot and $flags parameters. 1817 manual page for details on the $length, $prot and $flags parameters.
1251 1818
1252 The $length must be larger than zero and smaller than the actual 1819 The $length must be larger than zero and smaller than the actual
… …
1256 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1823 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1257 "IO::AIO::PROT_WRITE", 1824 "IO::AIO::PROT_WRITE",
1258 1825
1259 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1826 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1260 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1827 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1261 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1828 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1262 (which is set to "MAP_ANON" if your system only provides this 1829 "MAP_ANON" if your system only provides this constant),
1830 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1263 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1831 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1264 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1832 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1265 "IO::AIO::MAP_NONBLOCK" 1833 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
1834 "IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
1835 "IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1266 1836
1267 If $fh is "undef", then a file descriptor of -1 is passed. 1837 If $fh is "undef", then a file descriptor of -1 is passed.
1268 1838
1269 $offset is the offset from the start of the file - it generally must 1839 $offset is the offset from the start of the file - it generally must
1270 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1840 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1282 1852
1283 my $fast_md5 = md5 $data; 1853 my $fast_md5 = md5 $data;
1284 1854
1285 IO::AIO::munmap $scalar 1855 IO::AIO::munmap $scalar
1286 Removes a previous mmap and undefines the $scalar. 1856 Removes a previous mmap and undefines the $scalar.
1857
1858 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1859 $new_address = 0]
1860 Calls the Linux-specific mremap(2) system call. The $scalar must
1861 have been mapped by "IO::AIO::mmap", and $flags must currently
1862 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1863
1864 Returns true if successful, and false otherwise. If the underlying
1865 mmapped region has changed address, then the true value has the
1866 numerical value 1, otherwise it has the numerical value 0:
1867
1868 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1869 or die "mremap: $!";
1870
1871 if ($success*1) {
1872 warn "scalar has chanegd address in memory\n";
1873 }
1874
1875 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1876 implemented, but not supported and might go away in a future
1877 version.
1878
1879 On systems where this call is not supported or is not emulated, this
1880 call returns falls and sets $! to "ENOSYS".
1881
1882 IO::AIO::mlockall $flags
1883 Calls the "eio_mlockall_sync" function, which is like
1884 "aio_mlockall", but is blocking.
1287 1885
1288 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1886 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1289 Calls the "munlock" function, undoing the effects of a previous 1887 Calls the "munlock" function, undoing the effects of a previous
1290 "aio_mlock" call (see its description for details). 1888 "aio_mlock" call (see its description for details).
1291 1889
1292 IO::AIO::munlockall 1890 IO::AIO::munlockall
1293 Calls the "munlockall" function. 1891 Calls the "munlockall" function.
1294 1892
1295 On systems that do not implement "munlockall", this function returns 1893 On systems that do not implement "munlockall", this function returns
1296 ENOSYS, otherwise the return value of "munlockall". 1894 ENOSYS, otherwise the return value of "munlockall".
1895
1896 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1897 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1898 socket and return the new file handle on success, or sets $! and
1899 returns "undef" on error.
1900
1901 The remote name of the new socket will be stored in $sockaddr, which
1902 will be extended to allow for at least $sockaddr_maxlen octets. If
1903 the socket name does not fit into $sockaddr_maxlen octets, this is
1904 signaled by returning a longer string in $sockaddr, which might or
1905 might not be truncated.
1906
1907 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1908 $sockaddr_maxlen.
1909
1910 The main reasons to use this syscall rather than portable accept(2)
1911 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1912 and you can accept name-less sockets by specifying 0 for
1913 $sockaddr_maxlen, which is sadly not possible with perl's interface
1914 to "accept".
1915
1916 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1917 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1918 $w_off are "undef", then "NULL" is passed for these, otherwise they
1919 should be the file offset.
1920
1921 $r_fh and $w_fh should not refer to the same file, as splice might
1922 silently corrupt the data in this case.
1923
1924 The following symbol flag values are available:
1925 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1926 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1927
1928 See the splice(2) manpage for details.
1929
1930 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1931 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1932 description for "IO::AIO::splice" above for details.
1933
1934 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1935 Attempts to query or change the pipe buffer size. Obviously works
1936 only on pipes, and currently works only on GNU/Linux systems, and
1937 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1938 influence pipe buffer size on other systems, drop me a note.
1939
1940 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1941 This is a direct interface to the Linux pipe2(2) system call. If
1942 $flags is missing or 0, then this should be the same as a call to
1943 perl's built-in "pipe" function and create a new pipe, and works on
1944 systems that lack the pipe2 syscall. On win32, this case invokes
1945 "_pipe (..., 4096, O_BINARY)".
1946
1947 If $flags is non-zero, it tries to invoke the pipe2 system call with
1948 the given flags (Linux 2.6.27, glibc 2.9).
1949
1950 On success, the read and write file handles are returned.
1951
1952 On error, nothing will be returned. If the pipe2 syscall is missing
1953 and $flags is non-zero, fails with "ENOSYS".
1954
1955 Please refer to pipe2(2) for more info on the $flags, but at the
1956 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1957 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1958 supported.
1959
1960 Example: create a pipe race-free w.r.t. threads and fork:
1961
1962 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1963 or die "pipe2: $!\n";
1964
1965 $fh = IO::AIO::memfd_create $pathname[, $flags]
1966 This is a direct interface to the Linux memfd_create(2) system call.
1967 The (unhelpful) default for $flags is 0, but your default should be
1968 "IO::AIO::MFD_CLOEXEC".
1969
1970 On success, the new memfd filehandle is returned, otherwise returns
1971 "undef". If the memfd_create syscall is missing, fails with
1972 "ENOSYS".
1973
1974 Please refer to memfd_create(2) for more info on this call.
1975
1976 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1977 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1978
1979 Example: create a new memfd.
1980
1981 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1982 or die "memfd_create: $!\n";
1983
1984 $fh = IO::AIO::pidfd_open $pid[, $flags]
1985 This is an interface to the Linux pidfd_open(2) system call. The
1986 default for $flags is 0.
1987
1988 On success, a new pidfd filehandle is returned (that is already set
1989 to close-on-exec), otherwise returns "undef". If the syscall is
1990 missing, fails with "ENOSYS".
1991
1992 Example: open pid 6341 as pidfd.
1993
1994 my $fh = IO::AIO::pidfd_open 6341
1995 or die "pidfd_open: $!\n";
1996
1997 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
1998 $flags]]
1999 This is an interface to the Linux pidfd_send_signal system call. The
2000 default for $siginfo is "undef" and the default for $flags is 0.
2001
2002 Returns the system call status. If the syscall is missing, fails
2003 with "ENOSYS".
2004
2005 When specified, $siginfo must be a reference to a hash with one or
2006 more of the following members:
2007
2008 code - the "si_code" member
2009 pid - the "si_pid" member
2010 uid - the "si_uid" member
2011 value_int - the "si_value.sival_int" member
2012 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2013
2014 Example: send a SIGKILL to the specified process.
2015
2016 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2017 and die "pidfd_send_signal: $!\n";
2018
2019 Example: send a SIGKILL to the specified process with extra data.
2020
2021 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2022 and die "pidfd_send_signal: $!\n";
2023
2024 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2025 This is an interface to the Linux pidfd_getfd system call. The
2026 default for $flags is 0.
2027
2028 On success, returns a dup'ed copy of the target file descriptor
2029 (specified as an integer) returned (that is already set to
2030 close-on-exec), otherwise returns "undef". If the syscall is
2031 missing, fails with "ENOSYS".
2032
2033 Example: get a copy of standard error of another process and print
2034 soemthing to it.
2035
2036 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2037 or die "pidfd_getfd: $!\n";
2038 print $errfh "stderr\n";
2039
2040 $fh = IO::AIO::eventfd [$initval, [$flags]]
2041 This is a direct interface to the Linux eventfd(2) system call. The
2042 (unhelpful) defaults for $initval and $flags are 0 for both.
2043
2044 On success, the new eventfd filehandle is returned, otherwise
2045 returns "undef". If the eventfd syscall is missing, fails with
2046 "ENOSYS".
2047
2048 Please refer to eventfd(2) for more info on this call.
2049
2050 The following symbol flag values are available:
2051 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2052 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2053
2054 Example: create a new eventfd filehandle:
2055
2056 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2057 or die "eventfd: $!\n";
2058
2059 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2060 This is a direct interface to the Linux timerfd_create(2) system
2061 call. The (unhelpful) default for $flags is 0, but your default
2062 should be "IO::AIO::TFD_CLOEXEC".
2063
2064 On success, the new timerfd filehandle is returned, otherwise
2065 returns "undef". If the timerfd_create syscall is missing, fails
2066 with "ENOSYS".
2067
2068 Please refer to timerfd_create(2) for more info on this call.
2069
2070 The following $clockid values are available:
2071 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2072 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2073 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2074 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2075
2076 The following $flags values are available (Linux 2.6.27):
2077 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2078
2079 Example: create a new timerfd and set it to one-second repeated
2080 alarms, then wait for two alarms:
2081
2082 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2083 or die "timerfd_create: $!\n";
2084
2085 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2086 or die "timerfd_settime: $!\n";
2087
2088 for (1..2) {
2089 8 == sysread $fh, my $buf, 8
2090 or die "timerfd read failure\n";
2091
2092 printf "number of expirations (likely 1): %d\n",
2093 unpack "Q", $buf;
2094 }
2095
2096 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2097 $new_interval, $nbw_value
2098 This is a direct interface to the Linux timerfd_settime(2) system
2099 call. Please refer to its manpage for more info on this call.
2100
2101 The new itimerspec is specified using two (possibly fractional)
2102 second values, $new_interval and $new_value).
2103
2104 On success, the current interval and value are returned (as per
2105 "timerfd_gettime"). On failure, the empty list is returned.
2106
2107 The following $flags values are available:
2108 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2109
2110 See "IO::AIO::timerfd_create" for a full example.
2111
2112 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2113 This is a direct interface to the Linux timerfd_gettime(2) system
2114 call. Please refer to its manpage for more info on this call.
2115
2116 On success, returns the current values of interval and value for the
2117 given timerfd (as potentially fractional second values). On failure,
2118 the empty list is returned.
1297 2119
1298EVENT LOOP INTEGRATION 2120EVENT LOOP INTEGRATION
1299 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2121 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1300 automatically into many event loops: 2122 automatically into many event loops:
1301 2123
… …
1324 # Danga::Socket integration 2146 # Danga::Socket integration
1325 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 2147 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1326 \&IO::AIO::poll_cb); 2148 \&IO::AIO::poll_cb);
1327 2149
1328 FORK BEHAVIOUR 2150 FORK BEHAVIOUR
1329 This module should do "the right thing" when the process using it forks: 2151 Usage of pthreads in a program changes the semantics of fork
2152 considerably. Specifically, only async-safe functions can be called
2153 after fork. Perl doesn't know about this, so in general, you cannot call
2154 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2155 uses pthreads, so this applies, but many other extensions and (for
2156 inexplicable reasons) perl itself often is linked against pthreads, so
2157 this limitation applies to quite a lot of perls.
1330 2158
1331 Before the fork, IO::AIO enters a quiescent state where no requests can 2159 This module no longer tries to fight your OS, or POSIX. That means
1332 be added in other threads and no results will be processed. After the 2160 IO::AIO only works in the process that loaded it. Forking is fully
1333 fork the parent simply leaves the quiescent state and continues 2161 supported, but using IO::AIO in the child is not.
1334 request/result processing, while the child frees the request/result
1335 queue (so that the requests started before the fork will only be handled
1336 in the parent). Threads will be started on demand until the limit set in
1337 the parent process has been reached again.
1338 2162
1339 In short: the parent will, after a short pause, continue as if fork had 2163 You might get around by not *using* IO::AIO before (or after) forking.
1340 not been called, while the child will act as if IO::AIO has not been 2164 You could also try to call the IO::AIO::reinit function in the child:
1341 used yet. 2165
2166 IO::AIO::reinit
2167 Abandons all current requests and I/O threads and simply
2168 reinitialises all data structures. This is not an operation
2169 supported by any standards, but happens to work on GNU/Linux and
2170 some newer BSD systems.
2171
2172 The only reasonable use for this function is to call it after
2173 forking, if "IO::AIO" was used in the parent. Calling it while
2174 IO::AIO is active in the process will result in undefined behaviour.
2175 Calling it at any time will also result in any undefined (by POSIX)
2176 behaviour.
2177
2178 LINUX-SPECIFIC CALLS
2179 When a call is documented as "linux-specific" then this means it
2180 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2181 availability and compatibility of such calls regardless of the platform
2182 it is compiled on, so platforms such as FreeBSD which often implement
2183 these calls will work. When in doubt, call them and see if they fail wth
2184 "ENOSYS".
1342 2185
1343 MEMORY USAGE 2186 MEMORY USAGE
1344 Per-request usage: 2187 Per-request usage:
1345 2188
1346 Each aio request uses - depending on your architecture - around 100-200 2189 Each aio request uses - depending on your architecture - around 100-200
… …
1357 In the execution phase, some aio requests require more memory for 2200 In the execution phase, some aio requests require more memory for
1358 temporary buffers, and each thread requires a stack and other data 2201 temporary buffers, and each thread requires a stack and other data
1359 structures (usually around 16k-128k, depending on the OS). 2202 structures (usually around 16k-128k, depending on the OS).
1360 2203
1361KNOWN BUGS 2204KNOWN BUGS
1362 Known bugs will be fixed in the next release. 2205 Known bugs will be fixed in the next release :)
2206
2207KNOWN ISSUES
2208 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2209 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2210 non-created hash slots or other scalars I didn't think of. It's best to
2211 avoid such and either use scalar variables or making sure that the
2212 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2213
2214 I am not sure anything can be done about this, so this is considered a
2215 known issue, rather than a bug.
1363 2216
1364SEE ALSO 2217SEE ALSO
1365 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2218 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1366 more natural syntax. 2219 more natural syntax and IO::FDPass for file descriptor passing.
1367 2220
1368AUTHOR 2221AUTHOR
1369 Marc Lehmann <schmorp@schmorp.de> 2222 Marc Lehmann <schmorp@schmorp.de>
1370 http://home.schmorp.de/ 2223 http://home.schmorp.de/
1371 2224

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