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Revision 1.64 by root, Wed Apr 3 03:03:53 2019 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)
173 aio_realpath $path, $callback->($link) 180 aio_realpath $pathname, $callback->($path)
174 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
175 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
176 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
177 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
178 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
179 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
180 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)
181 aio_load $path, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
182 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
183 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
184 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
185 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)
186 aio_sync $callback->($status) 196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
187 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
188 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
189 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
190 aio_pathsync $path, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
191 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
192 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
193 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
194 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
195 aio_group $callback->(...) 206 aio_group $callback->(...)
196 aio_nop $callback->() 207 aio_nop $callback->()
… …
210 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
211 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
212 IO::AIO::nreqs 223 IO::AIO::nreqs
213 IO::AIO::nready 224 IO::AIO::nready
214 IO::AIO::npending 225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
229 IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
215 230
216 IO::AIO::sendfile $ofh, $ifh, $offset, $count 231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
217 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]
218 IO::AIO::madvise $scalar, $offset, $length, $advice 237 IO::AIO::madvise $scalar, $offset, $length, $advice
219 IO::AIO::mprotect $scalar, $offset, $length, $protect 238 IO::AIO::mprotect $scalar, $offset, $length, $protect
220 IO::AIO::munlock $scalar, $offset = 0, $length = undef 239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
221 IO::AIO::munlockall 240 IO::AIO::munlockall
222 241
223 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::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
252 IO::AIO::tee $r_fh, $w_fh, $length, $flags
253 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
254 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
255 $fh = IO::AIO::memfd_create $pathname[, $flags]
256 $fh = IO::AIO::eventfd [$initval, [$flags]]
257 $fh = IO::AIO::timerfd_create $clockid[, $flags]
258 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
259 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
260
261 API NOTES
224 All the "aio_*" calls are more or less thin wrappers around the syscall 262 All the "aio_*" calls are more or less thin wrappers around the syscall
225 with the same name (sans "aio_"). The arguments are similar or 263 with the same name (sans "aio_"). The arguments are similar or
226 identical, and they all accept an additional (and optional) $callback 264 identical, and they all accept an additional (and optional) $callback
227 argument which must be a code reference. This code reference will get 265 argument which must be a code reference. This code reference will be
228 called with the syscall return code (e.g. most syscalls return -1 on
229 error, unlike perl, which usually delivers "false") as its sole argument
230 after the given syscall has been executed asynchronously. 266 called after the syscall has been executed in an asynchronous fashion.
267 The results of the request will be passed as arguments to the callback
268 (and, if an error occured, in $!) - for most requests the syscall return
269 code (e.g. most syscalls return -1 on error, unlike perl, which usually
270 delivers "false").
271
272 Some requests (such as "aio_readdir") pass the actual results and
273 communicate failures by passing "undef".
231 274
232 All functions expecting a filehandle keep a copy of the filehandle 275 All functions expecting a filehandle keep a copy of the filehandle
233 internally until the request has finished. 276 internally until the request has finished.
234 277
235 All functions return request objects of type IO::AIO::REQ that allow 278 All functions return request objects of type IO::AIO::REQ that allow
236 further manipulation of those requests while they are in-flight. 279 further manipulation of those requests while they are in-flight.
237 280
238 The pathnames you pass to these routines *must* be absolute and encoded 281 The pathnames you pass to these routines *should* be absolute. The
239 as octets. The reason for the former is that at the time the request is 282 reason for this is that at the time the request is being executed, the
240 being executed, the current working directory could have changed. 283 current working directory could have changed. Alternatively, you can
241 Alternatively, you can make sure that you never change the current 284 make sure that you never change the current working directory anywhere
242 working directory anywhere in the program and then use relative paths. 285 in the program and then use relative paths. You can also take advantage
286 of IO::AIOs working directory abstraction, that lets you specify paths
287 relative to some previously-opened "working directory object" - see the
288 description of the "IO::AIO::WD" class later in this document.
243 289
244 To encode pathnames as octets, either make sure you either: a) always 290 To encode pathnames as octets, either make sure you either: a) always
245 pass in filenames you got from outside (command line, readdir etc.) 291 pass in filenames you got from outside (command line, readdir etc.)
246 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 292 without tinkering, b) are in your native filesystem encoding, c) use the
247 and encode your pathnames to the locale (or other) encoding in effect in 293 Encode module and encode your pathnames to the locale (or other)
248 the user environment, d) use Glib::filename_from_unicode on unicode 294 encoding in effect in the user environment, d) use
249 filenames or e) use something else to ensure your scalar has the correct 295 Glib::filename_from_unicode on unicode filenames or e) use something
250 contents. 296 else to ensure your scalar has the correct contents.
251 297
252 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 298 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
253 handles correctly whether it is set or not. 299 handles correctly whether it is set or not.
254 300
301 AIO REQUEST FUNCTIONS
255 $prev_pri = aioreq_pri [$pri] 302 $prev_pri = aioreq_pri [$pri]
256 Returns the priority value that would be used for the next request 303 Returns the priority value that would be used for the next request
257 and, if $pri is given, sets the priority for the next aio request. 304 and, if $pri is given, sets the priority for the next aio request.
258 305
259 The default priority is 0, the minimum and maximum priorities are -4 306 The default priority is 0, the minimum and maximum priorities are -4
… …
281 Similar to "aioreq_pri", but subtracts the given value from the 328 Similar to "aioreq_pri", but subtracts the given value from the
282 current priority, so the effect is cumulative. 329 current priority, so the effect is cumulative.
283 330
284 aio_open $pathname, $flags, $mode, $callback->($fh) 331 aio_open $pathname, $flags, $mode, $callback->($fh)
285 Asynchronously open or create a file and call the callback with a 332 Asynchronously open or create a file and call the callback with a
286 newly created filehandle for the file. 333 newly created filehandle for the file (or "undef" in case of an
334 error).
287 335
288 The pathname passed to "aio_open" must be absolute. See API NOTES, 336 The pathname passed to "aio_open" must be absolute. See API NOTES,
289 above, for an explanation. 337 above, for an explanation.
290 338
291 The $flags argument is a bitmask. See the "Fcntl" module for a list. 339 The $flags argument is a bitmask. See the "Fcntl" module for a list.
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314 "O_APPEND"), the following POSIX and non-POSIX constants are 362 "O_APPEND"), the following POSIX and non-POSIX constants are
315 available (missing ones on your system are, as usual, 0): 363 available (missing ones on your system are, as usual, 0):
316 364
317 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 365 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
318 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 366 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
319 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". 367 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
368 and "O_ACCMODE".
320 369
321 aio_close $fh, $callback->($status) 370 aio_close $fh, $callback->($status)
322 Asynchronously close a file and call the callback with the result 371 Asynchronously close a file and call the callback with the result
323 code. 372 code.
324 373
… …
330 will use dup2 to overwrite the file descriptor with the write-end of 379 will use dup2 to overwrite the file descriptor with the write-end of
331 a pipe (the pipe fd will be created on demand and will be cached). 380 a pipe (the pipe fd will be created on demand and will be cached).
332 381
333 Or in other words: the file descriptor will be closed, but it will 382 Or in other words: the file descriptor will be closed, but it will
334 not be free for reuse until the perl filehandle is closed. 383 not be free for reuse until the perl filehandle is closed.
384
385 aio_seek $fh, $offset, $whence, $callback->($offs)
386 Seeks the filehandle to the new $offset, similarly to perl's
387 "sysseek". The $whence can use the traditional values (0 for
388 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
389 "IO::AIO::SEEK_END").
390
391 The resulting absolute offset will be passed to the callback, or -1
392 in case of an error.
393
394 In theory, the $whence constants could be different than the
395 corresponding values from Fcntl, but perl guarantees they are the
396 same, so don't panic.
397
398 As a GNU/Linux (and maybe Solaris) extension, also the constants
399 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
400 could be found. No guarantees about suitability for use in
401 "aio_seek" or Perl's "sysseek" can be made though, although I would
402 naively assume they "just work".
335 403
336 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 404 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
337 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
338 Reads or writes $length bytes from or to the specified $fh and 406 Reads or writes $length bytes from or to the specified $fh and
339 $offset into the scalar given by $data and offset $dataoffset and 407 $offset into the scalar given by $data and offset $dataoffset and
340 calls the callback without the actual number of bytes read (or -1 on 408 calls the callback with the actual number of bytes transferred (or
341 error, just like the syscall). 409 -1 on error, just like the syscall).
342 410
343 "aio_read" will, like "sysread", shrink or grow the $data scalar to 411 "aio_read" will, like "sysread", shrink or grow the $data scalar to
344 offset plus the actual number of bytes read. 412 offset plus the actual number of bytes read.
345 413
346 If $offset is undefined, then the current file descriptor offset 414 If $offset is undefined, then the current file descriptor offset
… …
403 As native sendfile syscalls (as practically any non-POSIX interface 471 As native sendfile syscalls (as practically any non-POSIX interface
404 hacked together in a hurry to improve benchmark numbers) tend to be 472 hacked together in a hurry to improve benchmark numbers) tend to be
405 rather buggy on many systems, this implementation tries to work 473 rather buggy on many systems, this implementation tries to work
406 around some known bugs in Linux and FreeBSD kernels (probably 474 around some known bugs in Linux and FreeBSD kernels (probably
407 others, too), but that might fail, so you really really should check 475 others, too), but that might fail, so you really really should check
408 the return value of "aio_sendfile" - fewre bytes than expected might 476 the return value of "aio_sendfile" - fewer bytes than expected might
409 have been transferred. 477 have been transferred.
410 478
411 aio_readahead $fh,$offset,$length, $callback->($retval) 479 aio_readahead $fh,$offset,$length, $callback->($retval)
412 "aio_readahead" populates the page cache with data from a file so 480 "aio_readahead" populates the page cache with data from a file so
413 that subsequent reads from that file will not block on disk I/O. The 481 that subsequent reads from that file will not block on disk I/O. The
… …
417 to a page boundary and bytes are read up to the next page boundary 485 to a page boundary and bytes are read up to the next page boundary
418 greater than or equal to (off-set+length). "aio_readahead" does not 486 greater than or equal to (off-set+length). "aio_readahead" does not
419 read beyond the end of the file. The current file offset of the file 487 read beyond the end of the file. The current file offset of the file
420 is left unchanged. 488 is left unchanged.
421 489
422 If that syscall doesn't exist (likely if your OS isn't Linux) it 490 If that syscall doesn't exist (likely if your kernel isn't Linux) it
423 will be emulated by simply reading the data, which would have a 491 will be emulated by simply reading the data, which would have a
424 similar effect. 492 similar effect.
425 493
426 aio_stat $fh_or_path, $callback->($status) 494 aio_stat $fh_or_path, $callback->($status)
427 aio_lstat $fh, $callback->($status) 495 aio_lstat $fh, $callback->($status)
428 Works like perl's "stat" or "lstat" in void context. The callback 496 Works almost exactly like perl's "stat" or "lstat" in void context.
429 will be called after the stat and the results will be available 497 The callback will be called after the stat and the results will be
430 using "stat _" or "-s _" etc... 498 available using "stat _" or "-s _" and other tests (with the
499 exception of "-B" and "-T").
431 500
432 The pathname passed to "aio_stat" must be absolute. See API NOTES, 501 The pathname passed to "aio_stat" must be absolute. See API NOTES,
433 above, for an explanation. 502 above, for an explanation.
434 503
435 Currently, the stats are always 64-bit-stats, i.e. instead of 504 Currently, the stats are always 64-bit-stats, i.e. instead of
… …
443 back on traditional behaviour). 512 back on traditional behaviour).
444 513
445 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 514 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
446 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 515 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
447 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 516 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
517
518 To access higher resolution stat timestamps, see "SUBSECOND STAT
519 TIME ACCESS".
448 520
449 Example: Print the length of /etc/passwd: 521 Example: Print the length of /etc/passwd:
450 522
451 aio_stat "/etc/passwd", sub { 523 aio_stat "/etc/passwd", sub {
452 $_[0] and die "stat failed: $!"; 524 $_[0] and die "stat failed: $!";
… …
499 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 571 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
500 Works like perl's "utime" function (including the special case of 572 Works like perl's "utime" function (including the special case of
501 $atime and $mtime being undef). Fractional times are supported if 573 $atime and $mtime being undef). Fractional times are supported if
502 the underlying syscalls support them. 574 the underlying syscalls support them.
503 575
504 When called with a pathname, uses utimes(2) if available, otherwise 576 When called with a pathname, uses utimensat(2) or utimes(2) if
505 utime(2). If called on a file descriptor, uses futimes(2) if 577 available, otherwise utime(2). If called on a file descriptor, uses
506 available, otherwise returns ENOSYS, so this is not portable. 578 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
579 this is not portable.
507 580
508 Examples: 581 Examples:
509 582
510 # set atime and mtime to current time (basically touch(1)): 583 # set atime and mtime to current time (basically touch(1)):
511 aio_utime "path", undef, undef; 584 aio_utime "path", undef, undef;
… …
525 aio_chown "path", 0, undef; 598 aio_chown "path", 0, undef;
526 599
527 aio_truncate $fh_or_path, $offset, $callback->($status) 600 aio_truncate $fh_or_path, $offset, $callback->($status)
528 Works like truncate(2) or ftruncate(2). 601 Works like truncate(2) or ftruncate(2).
529 602
603 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
604 Allocates or frees disk space according to the $mode argument. See
605 the linux "fallocate" documentation for details.
606
607 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
608 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
609 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
610
611 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
612 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
613 "FALLOC_FL_INSERT_RANGE" to insert a range and
614 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
615 fallocate(2) manpage).
616
617 The file system block size used by "fallocate" is presumably the
618 "f_bsize" returned by "statvfs", but different filesystems and
619 filetypes can dictate other limitations.
620
621 If "fallocate" isn't available or cannot be emulated (currently no
622 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
623
530 aio_chmod $fh_or_path, $mode, $callback->($status) 624 aio_chmod $fh_or_path, $mode, $callback->($status)
531 Works like perl's "chmod" function. 625 Works like perl's "chmod" function.
532 626
533 aio_unlink $pathname, $callback->($status) 627 aio_unlink $pathname, $callback->($status)
534 Asynchronously unlink (delete) a file and call the callback with the 628 Asynchronously unlink (delete) a file and call the callback with the
535 result code. 629 result code.
536 630
537 aio_mknod $path, $mode, $dev, $callback->($status) 631 aio_mknod $pathname, $mode, $dev, $callback->($status)
538 [EXPERIMENTAL] 632 [EXPERIMENTAL]
539 633
540 Asynchronously create a device node (or fifo). See mknod(2). 634 Asynchronously create a device node (or fifo). See mknod(2).
541 635
542 The only (POSIX-) portable way of calling this function is: 636 The only (POSIX-) portable way of calling this function is:
543 637
544 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 638 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
545 639
546 See "aio_stat" for info about some potentially helpful extra 640 See "aio_stat" for info about some potentially helpful extra
547 constants and functions. 641 constants and functions.
548 642
549 aio_link $srcpath, $dstpath, $callback->($status) 643 aio_link $srcpath, $dstpath, $callback->($status)
… …
553 aio_symlink $srcpath, $dstpath, $callback->($status) 647 aio_symlink $srcpath, $dstpath, $callback->($status)
554 Asynchronously create a new symbolic link to the existing object at 648 Asynchronously create a new symbolic link to the existing object at
555 $srcpath at the path $dstpath and call the callback with the result 649 $srcpath at the path $dstpath and call the callback with the result
556 code. 650 code.
557 651
558 aio_readlink $path, $callback->($link) 652 aio_readlink $pathname, $callback->($link)
559 Asynchronously read the symlink specified by $path and pass it to 653 Asynchronously read the symlink specified by $path and pass it to
560 the callback. If an error occurs, nothing or undef gets passed to 654 the callback. If an error occurs, nothing or undef gets passed to
561 the callback. 655 the callback.
562 656
563 aio_realpath $path, $callback->($path) 657 aio_realpath $pathname, $callback->($path)
564 Asynchronously make the path absolute and resolve any symlinks in 658 Asynchronously make the path absolute and resolve any symlinks in
565 $path. The resulting path only consists of directories (Same as 659 $path. The resulting path only consists of directories (same as
566 Cwd::realpath). 660 Cwd::realpath).
567 661
568 This request can be used to get the absolute path of the current 662 This request can be used to get the absolute path of the current
569 working directory by passing it a path of . (a single dot). 663 working directory by passing it a path of . (a single dot).
570 664
571 aio_rename $srcpath, $dstpath, $callback->($status) 665 aio_rename $srcpath, $dstpath, $callback->($status)
572 Asynchronously rename the object at $srcpath to $dstpath, just as 666 Asynchronously rename the object at $srcpath to $dstpath, just as
573 rename(2) and call the callback with the result code. 667 rename(2) and call the callback with the result code.
668
669 On systems that support the AIO::WD working directory abstraction
670 natively, the case "[$wd, "."]" as $srcpath is specialcased -
671 instead of failing, "rename" is called on the absolute path of $wd.
672
673 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
674 Basically a version of "aio_rename" with an additional $flags
675 argument. Calling this with "$flags=0" is the same as calling
676 "aio_rename".
677
678 Non-zero flags are currently only supported on GNU/Linux systems
679 that support renameat2. Other systems fail with "ENOSYS" in this
680 case.
681
682 The following constants are available (missing ones are, as usual
683 0), see renameat2(2) for details:
684
685 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
686 "IO::AIO::RENAME_WHITEOUT".
574 687
575 aio_mkdir $pathname, $mode, $callback->($status) 688 aio_mkdir $pathname, $mode, $callback->($status)
576 Asynchronously mkdir (create) a directory and call the callback with 689 Asynchronously mkdir (create) a directory and call the callback with
577 the result code. $mode will be modified by the umask at the time the 690 the result code. $mode will be modified by the umask at the time the
578 request is executed, so do not change your umask. 691 request is executed, so do not change your umask.
579 692
580 aio_rmdir $pathname, $callback->($status) 693 aio_rmdir $pathname, $callback->($status)
581 Asynchronously rmdir (delete) a directory and call the callback with 694 Asynchronously rmdir (delete) a directory and call the callback with
582 the result code. 695 the result code.
583 696
697 On systems that support the AIO::WD working directory abstraction
698 natively, the case "[$wd, "."]" is specialcased - instead of
699 failing, "rmdir" is called on the absolute path of $wd.
700
584 aio_readdir $pathname, $callback->($entries) 701 aio_readdir $pathname, $callback->($entries)
585 Unlike the POSIX call of the same name, "aio_readdir" reads an 702 Unlike the POSIX call of the same name, "aio_readdir" reads an
586 entire directory (i.e. opendir + readdir + closedir). The entries 703 entire directory (i.e. opendir + readdir + closedir). The entries
587 will not be sorted, and will NOT include the "." and ".." entries. 704 will not be sorted, and will NOT include the "." and ".." entries.
588 705
589 The callback is passed a single argument which is either "undef" or 706 The callback is passed a single argument which is either "undef" or
590 an array-ref with the filenames. 707 an array-ref with the filenames.
591 708
592 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 709 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
593 Quite similar to "aio_readdir", but the $flags argument allows to 710 Quite similar to "aio_readdir", but the $flags argument allows one
594 tune behaviour and output format. In case of an error, $entries will 711 to tune behaviour and output format. In case of an error, $entries
595 be "undef". 712 will be "undef".
596 713
597 The flags are a combination of the following constants, ORed 714 The flags are a combination of the following constants, ORed
598 together (the flags will also be passed to the callback, possibly 715 together (the flags will also be passed to the callback, possibly
599 modified): 716 modified):
600 717
601 IO::AIO::READDIR_DENTS 718 IO::AIO::READDIR_DENTS
602 When this flag is off, then the callback gets an arrayref 719 Normally the callback gets an arrayref consisting of names only
603 consisting of names only (as with "aio_readdir"), otherwise it 720 (as with "aio_readdir"). If this flag is set, then the callback
604 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 721 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
605 describing a single directory entry in more detail. 722 describing a single directory entry in more detail:
606 723
607 $name is the name of the entry. 724 $name is the name of the entry.
608 725
609 $type is one of the "IO::AIO::DT_xxx" constants: 726 $type is one of the "IO::AIO::DT_xxx" constants:
610 727
611 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 728 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
612 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 729 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
613 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 730 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
614 731
615 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 732 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
616 you need to know, you have to run stat yourself. Also, for speed 733 you need to know, you have to run stat yourself. Also, for
617 reasons, the $type scalars are read-only: you can not modify 734 speed/memory reasons, the $type scalars are read-only: you must
618 them. 735 not modify them.
619 736
620 $inode is the inode number (which might not be exact on systems 737 $inode is the inode number (which might not be exact on systems
621 with 64 bit inode numbers and 32 bit perls). This field has 738 with 64 bit inode numbers and 32 bit perls). This field has
622 unspecified content on systems that do not deliver the inode 739 unspecified content on systems that do not deliver the inode
623 information. 740 information.
… …
635 of which names with short names are tried first. 752 of which names with short names are tried first.
636 753
637 IO::AIO::READDIR_STAT_ORDER 754 IO::AIO::READDIR_STAT_ORDER
638 When this flag is set, then the names will be returned in an 755 When this flag is set, then the names will be returned in an
639 order suitable for stat()'ing each one. That is, when you plan 756 order suitable for stat()'ing each one. That is, when you plan
640 to stat() all files in the given directory, then the returned 757 to stat() most or all files in the given directory, then the
641 order will likely be fastest. 758 returned order will likely be faster.
642 759
643 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 760 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
644 specified, then the likely dirs come first, resulting in a less 761 specified, then the likely dirs come first, resulting in a less
645 optimal stat order. 762 optimal stat order for stat'ing all entries, but likely a more
763 optimal order for finding subdirectories.
646 764
647 IO::AIO::READDIR_FOUND_UNKNOWN 765 IO::AIO::READDIR_FOUND_UNKNOWN
648 This flag should not be set when calling "aio_readdirx". 766 This flag should not be set when calling "aio_readdirx".
649 Instead, it is being set by "aio_readdirx", when any of the 767 Instead, it is being set by "aio_readdirx", when any of the
650 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 768 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
651 flag therefore indicates that all $type's are known, which can 769 flag therefore indicates that all $type's are known, which can
652 be used to speed up some algorithms. 770 be used to speed up some algorithms.
653 771
772 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
773 Opens, reads and closes the given file. The data is put into $data,
774 which is resized as required.
775
776 If $offset is negative, then it is counted from the end of the file.
777
778 If $length is zero, then the remaining length of the file is used.
779 Also, in this case, the same limitations to modifying $data apply as
780 when IO::AIO::mmap is used, i.e. it must only be modified in-place
781 with "substr". If the size of the file is known, specifying a
782 non-zero $length results in a performance advantage.
783
784 This request is similar to the older "aio_load" request, but since
785 it is a single request, it might be more efficient to use.
786
787 Example: load /etc/passwd into $passwd.
788
789 my $passwd;
790 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
791 $_[0] >= 0
792 or die "/etc/passwd: $!\n";
793
794 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
795 print $passwd;
796 };
797 IO::AIO::flush;
798
654 aio_load $path, $data, $callback->($status) 799 aio_load $pathname, $data, $callback->($status)
655 This is a composite request that tries to fully load the given file 800 This is a composite request that tries to fully load the given file
656 into memory. Status is the same as with aio_read. 801 into memory. Status is the same as with aio_read.
802
803 Using "aio_slurp" might be more efficient, as it is a single
804 request.
657 805
658 aio_copy $srcpath, $dstpath, $callback->($status) 806 aio_copy $srcpath, $dstpath, $callback->($status)
659 Try to copy the *file* (directories not supported as either source 807 Try to copy the *file* (directories not supported as either source
660 or destination) from $srcpath to $dstpath and call the callback with 808 or destination) from $srcpath to $dstpath and call the callback with
661 a status of 0 (ok) or -1 (error, see $!). 809 a status of 0 (ok) or -1 (error, see $!).
662 810
811 Existing destination files will be truncated.
812
663 This is a composite request that creates the destination file with 813 This is a composite request that creates the destination file with
664 mode 0200 and copies the contents of the source file into it using 814 mode 0200 and copies the contents of the source file into it using
665 "aio_sendfile", followed by restoring atime, mtime, access mode and 815 "aio_sendfile", followed by restoring atime, mtime, access mode and
666 uid/gid, in that order. 816 uid/gid, in that order.
667 817
… …
676 826
677 This is a composite request that tries to rename(2) the file first; 827 This is a composite request that tries to rename(2) the file first;
678 if rename fails with "EXDEV", it copies the file with "aio_copy" 828 if rename fails with "EXDEV", it copies the file with "aio_copy"
679 and, if that is successful, unlinks the $srcpath. 829 and, if that is successful, unlinks the $srcpath.
680 830
681 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 831 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
682 Scans a directory (similar to "aio_readdir") but additionally tries 832 Scans a directory (similar to "aio_readdir") but additionally tries
683 to efficiently separate the entries of directory $path into two sets 833 to efficiently separate the entries of directory $path into two sets
684 of names, directories you can recurse into (directories), and ones 834 of names, directories you can recurse into (directories), and ones
685 you cannot recurse into (everything else, including symlinks to 835 you cannot recurse into (everything else, including symlinks to
686 directories). 836 directories).
687 837
688 "aio_scandir" is a composite request that creates of many sub 838 "aio_scandir" is a composite request that generates many sub
689 requests_ $maxreq specifies the maximum number of outstanding aio 839 requests. $maxreq specifies the maximum number of outstanding aio
690 requests that this function generates. If it is "<= 0", then a 840 requests that this function generates. If it is "<= 0", then a
691 suitable default will be chosen (currently 4). 841 suitable default will be chosen (currently 4).
692 842
693 On error, the callback is called without arguments, otherwise it 843 On error, the callback is called without arguments, otherwise it
694 receives two array-refs with path-relative entry names. 844 receives two array-refs with path-relative entry names.
… …
719 Then entries will be sorted into likely directories a non-initial 869 Then entries will be sorted into likely directories a non-initial
720 dot currently) and likely non-directories (see "aio_readdirx"). Then 870 dot currently) and likely non-directories (see "aio_readdirx"). Then
721 every entry plus an appended "/." will be "stat"'ed, likely 871 every entry plus an appended "/." will be "stat"'ed, likely
722 directories first, in order of their inode numbers. If that 872 directories first, in order of their inode numbers. If that
723 succeeds, it assumes that the entry is a directory or a symlink to 873 succeeds, it assumes that the entry is a directory or a symlink to
724 directory (which will be checked seperately). This is often faster 874 directory (which will be checked separately). This is often faster
725 than stat'ing the entry itself because filesystems might detect the 875 than stat'ing the entry itself because filesystems might detect the
726 type of the entry without reading the inode data (e.g. ext2fs 876 type of the entry without reading the inode data (e.g. ext2fs
727 filetype feature), even on systems that cannot return the filetype 877 filetype feature), even on systems that cannot return the filetype
728 information on readdir. 878 information on readdir.
729 879
… …
735 885
736 It will also likely work on non-POSIX filesystems with reduced 886 It will also likely work on non-POSIX filesystems with reduced
737 efficiency as those tend to return 0 or 1 as link counts, which 887 efficiency as those tend to return 0 or 1 as link counts, which
738 disables the directory counting heuristic. 888 disables the directory counting heuristic.
739 889
740 aio_rmtree $path, $callback->($status) 890 aio_rmtree $pathname, $callback->($status)
741 Delete a directory tree starting (and including) $path, return the 891 Delete a directory tree starting (and including) $path, return the
742 status of the final "rmdir" only. This is a composite request that 892 status of the final "rmdir" only. This is a composite request that
743 uses "aio_scandir" to recurse into and rmdir directories, and unlink 893 uses "aio_scandir" to recurse into and rmdir directories, and unlink
744 everything else. 894 everything else.
745 895
896 aio_fcntl $fh, $cmd, $arg, $callback->($status)
897 aio_ioctl $fh, $request, $buf, $callback->($status)
898 These work just like the "fcntl" and "ioctl" built-in functions,
899 except they execute asynchronously and pass the return value to the
900 callback.
901
902 Both calls can be used for a lot of things, some of which make more
903 sense to run asynchronously in their own thread, while some others
904 make less sense. For example, calls that block waiting for external
905 events, such as locking, will also lock down an I/O thread while it
906 is waiting, which can deadlock the whole I/O system. At the same
907 time, there might be no alternative to using a thread to wait.
908
909 So in general, you should only use these calls for things that do
910 (filesystem) I/O, not for things that wait for other events
911 (network, other processes), although if you are careful and know
912 what you are doing, you still can.
913
914 The following constants are available (missing ones are, as usual
915 0):
916
917 "F_DUPFD_CLOEXEC",
918
919 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
920
921 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
922 "FIDEDUPERANGE".
923
924 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
925 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
926
927 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
928 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
929 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
930
931 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
932 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
933 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
934 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
935 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
936
937 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
938 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
939 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
940 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
941 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
942 "FS_XFLAG_HASATTR",
943
746 aio_sync $callback->($status) 944 aio_sync $callback->($status)
747 Asynchronously call sync and call the callback when finished. 945 Asynchronously call sync and call the callback when finished.
748 946
749 aio_fsync $fh, $callback->($status) 947 aio_fsync $fh, $callback->($status)
750 Asynchronously call fsync on the given filehandle and call the 948 Asynchronously call fsync on the given filehandle and call the
… …
754 Asynchronously call fdatasync on the given filehandle and call the 952 Asynchronously call fdatasync on the given filehandle and call the
755 callback with the fdatasync result code. 953 callback with the fdatasync result code.
756 954
757 If this call isn't available because your OS lacks it or it couldn't 955 If this call isn't available because your OS lacks it or it couldn't
758 be detected, it will be emulated by calling "fsync" instead. 956 be detected, it will be emulated by calling "fsync" instead.
957
958 aio_syncfs $fh, $callback->($status)
959 Asynchronously call the syncfs syscall to sync the filesystem
960 associated to the given filehandle and call the callback with the
961 syncfs result code. If syncfs is not available, calls sync(), but
962 returns -1 and sets errno to "ENOSYS" nevertheless.
759 963
760 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 964 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
761 Sync the data portion of the file specified by $offset and $length 965 Sync the data portion of the file specified by $offset and $length
762 to disk (but NOT the metadata), by calling the Linux-specific 966 to disk (but NOT the metadata), by calling the Linux-specific
763 sync_file_range call. If sync_file_range is not available or it 967 sync_file_range call. If sync_file_range is not available or it
… …
767 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 971 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
768 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 972 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
769 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 973 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
770 manpage for details. 974 manpage for details.
771 975
772 aio_pathsync $path, $callback->($status) 976 aio_pathsync $pathname, $callback->($status)
773 This request tries to open, fsync and close the given path. This is 977 This request tries to open, fsync and close the given path. This is
774 a composite request intended to sync directories after directory 978 a composite request intended to sync directories after directory
775 operations (E.g. rename). This might not work on all operating 979 operations (E.g. rename). This might not work on all operating
776 systems or have any specific effect, but usually it makes sure that 980 systems or have any specific effect, but usually it makes sure that
777 directory changes get written to disc. It works for anything that 981 directory changes get written to disc. It works for anything that
… …
780 Future versions of this function might fall back to other methods 984 Future versions of this function might fall back to other methods
781 when "fsync" on the directory fails (such as calling "sync"). 985 when "fsync" on the directory fails (such as calling "sync").
782 986
783 Passes 0 when everything went ok, and -1 on error. 987 Passes 0 when everything went ok, and -1 on error.
784 988
785 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 989 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
786 $callback->($status) 990 $callback->($status)
787 This is a rather advanced IO::AIO call, which only works on 991 This is a rather advanced IO::AIO call, which only works on
788 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 992 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
789 also works on data scalars managed by the Sys::Mmap or Mmap modules, 993 also works on data scalars managed by the Sys::Mmap or Mmap modules,
790 note that the scalar must only be modified in-place while an aio 994 note that the scalar must only be modified in-place while an aio
… …
792 996
793 It calls the "msync" function of your OS, if available, with the 997 It calls the "msync" function of your OS, if available, with the
794 memory area starting at $offset in the string and ending $length 998 memory area starting at $offset in the string and ending $length
795 bytes later. If $length is negative, counts from the end, and if 999 bytes later. If $length is negative, counts from the end, and if
796 $length is "undef", then it goes till the end of the string. The 1000 $length is "undef", then it goes till the end of the string. The
797 flags can be a combination of "IO::AIO::MS_ASYNC", 1001 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
798 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 1002 an optional "IO::AIO::MS_INVALIDATE".
799 1003
800 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 1004 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
801 $callback->($status) 1005 $callback->($status)
802 This is a rather advanced IO::AIO call, which works best on 1006 This is a rather advanced IO::AIO call, which works best on
803 mmap(2)ed scalars. 1007 mmap(2)ed scalars.
804 1008
805 It touches (reads or writes) all memory pages in the specified range 1009 It touches (reads or writes) all memory pages in the specified range
806 inside the scalar. All caveats and parameters are the same as for 1010 inside the scalar. All caveats and parameters are the same as for
807 "aio_msync", above, except for flags, which must be either 0 (which 1011 "aio_msync", above, except for flags, which must be either 0 (which
808 reads all pages and ensures they are instantiated) or 1012 reads all pages and ensures they are instantiated) or
809 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 1013 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
810 and writing an octet from it, which dirties the page). 1014 and writing an octet from it, which dirties the page).
811 1015
812 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1016 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
813 This is a rather advanced IO::AIO call, which works best on 1017 This is a rather advanced IO::AIO call, which works best on
814 mmap(2)ed scalars. 1018 mmap(2)ed scalars.
… …
834 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1038 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
835 aio_mlock $data; # mlock in background 1039 aio_mlock $data; # mlock in background
836 1040
837 aio_mlockall $flags, $callback->($status) 1041 aio_mlockall $flags, $callback->($status)
838 Calls the "mlockall" function with the given $flags (a combination 1042 Calls the "mlockall" function with the given $flags (a combination
839 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). 1043 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1044 "IO::AIO::MCL_ONFAULT").
840 1045
841 On systems that do not implement "mlockall", this function returns 1046 On systems that do not implement "mlockall", this function returns
842 -1 and sets errno to "ENOSYS". 1047 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1048 supported by the system result in a return value of -1 with errno
1049 being set to "EINVAL".
843 1050
844 Note that the corresponding "munlockall" is synchronous and is 1051 Note that the corresponding "munlockall" is synchronous and is
845 documented under "MISCELLANEOUS FUNCTIONS". 1052 documented under "MISCELLANEOUS FUNCTIONS".
846 1053
847 Example: asynchronously lock all current and future pages into 1054 Example: asynchronously lock all current and future pages into
848 memory. 1055 memory.
849 1056
850 aio_mlockall IO::AIO::MCL_FUTURE; 1057 aio_mlockall IO::AIO::MCL_FUTURE;
1058
1059 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1060 Queries the extents of the given file (by calling the Linux "FIEMAP"
1061 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1062 details). If the ioctl is not available on your OS, then this
1063 request will fail with "ENOSYS".
1064
1065 $start is the starting offset to query extents for, $length is the
1066 size of the range to query - if it is "undef", then the whole file
1067 will be queried.
1068
1069 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1070 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1071 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1072 query the data portion.
1073
1074 $count is the maximum number of extent records to return. If it is
1075 "undef", then IO::AIO queries all extents of the range. As a very
1076 special case, if it is 0, then the callback receives the number of
1077 extents instead of the extents themselves (which is unreliable, see
1078 below).
1079
1080 If an error occurs, the callback receives no arguments. The special
1081 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1082
1083 Otherwise, the callback receives an array reference with extent
1084 structures. Each extent structure is an array reference itself, with
1085 the following members:
1086
1087 [$logical, $physical, $length, $flags]
1088
1089 Flags is any combination of the following flag values (typically
1090 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1091
1092 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1093 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1094 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1095 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1096 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1097 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1098 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1099 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1100
1101 At the time of this writing (Linux 3.2), this request is unreliable
1102 unless $count is "undef", as the kernel has all sorts of bugs
1103 preventing it to return all extents of a range for files with a
1104 large number of extents. The code (only) works around all these
1105 issues if $count is "undef".
851 1106
852 aio_group $callback->(...) 1107 aio_group $callback->(...)
853 This is a very special aio request: Instead of doing something, it 1108 This is a very special aio request: Instead of doing something, it
854 is a container for other aio requests, which is useful if you want 1109 is a container for other aio requests, which is useful if you want
855 to bundle many requests into a single, composite, request with a 1110 to bundle many requests into a single, composite, request with a
… …
889 While it is theoretically handy to have simple I/O scheduling 1144 While it is theoretically handy to have simple I/O scheduling
890 requests like sleep and file handle readable/writable, the overhead 1145 requests like sleep and file handle readable/writable, the overhead
891 this creates is immense (it blocks a thread for a long time) so do 1146 this creates is immense (it blocks a thread for a long time) so do
892 not use this function except to put your application under 1147 not use this function except to put your application under
893 artificial I/O pressure. 1148 artificial I/O pressure.
1149
1150 IO::AIO::WD - multiple working directories
1151 Your process only has one current working directory, which is used by
1152 all threads. This makes it hard to use relative paths (some other
1153 component could call "chdir" at any time, and it is hard to control when
1154 the path will be used by IO::AIO).
1155
1156 One solution for this is to always use absolute paths. This usually
1157 works, but can be quite slow (the kernel has to walk the whole path on
1158 every access), and can also be a hassle to implement.
1159
1160 Newer POSIX systems have a number of functions (openat, fdopendir,
1161 futimensat and so on) that make it possible to specify working
1162 directories per operation.
1163
1164 For portability, and because the clowns who "designed", or shall I
1165 write, perpetrated this new interface were obviously half-drunk, this
1166 abstraction cannot be perfect, though.
1167
1168 IO::AIO allows you to convert directory paths into a so-called
1169 IO::AIO::WD object. This object stores the canonicalised, absolute
1170 version of the path, and on systems that allow it, also a directory file
1171 descriptor.
1172
1173 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1174 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1175 object and a pathname instead (or the IO::AIO::WD object alone, which
1176 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1177 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1178 relative to that IO::AIO::WD object.
1179
1180 For example, to get a wd object for /etc and then stat passwd inside,
1181 you would write:
1182
1183 aio_wd "/etc", sub {
1184 my $etcdir = shift;
1185
1186 # although $etcdir can be undef on error, there is generally no reason
1187 # to check for errors here, as aio_stat will fail with ENOENT
1188 # when $etcdir is undef.
1189
1190 aio_stat [$etcdir, "passwd"], sub {
1191 # yay
1192 };
1193 };
1194
1195 The fact that "aio_wd" is a request and not a normal function shows that
1196 creating an IO::AIO::WD object is itself a potentially blocking
1197 operation, which is why it is done asynchronously.
1198
1199 To stat the directory obtained with "aio_wd" above, one could write
1200 either of the following three request calls:
1201
1202 aio_lstat "/etc" , sub { ... # pathname as normal string
1203 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1204 aio_lstat $wd , sub { ... # shorthand for the previous
1205
1206 As with normal pathnames, IO::AIO keeps a copy of the working directory
1207 object and the pathname string, so you could write the following without
1208 causing any issues due to $path getting reused:
1209
1210 my $path = [$wd, undef];
1211
1212 for my $name (qw(abc def ghi)) {
1213 $path->[1] = $name;
1214 aio_stat $path, sub {
1215 # ...
1216 };
1217 }
1218
1219 There are some caveats: when directories get renamed (or deleted), the
1220 pathname string doesn't change, so will point to the new directory (or
1221 nowhere at all), while the directory fd, if available on the system,
1222 will still point to the original directory. Most functions accepting a
1223 pathname will use the directory fd on newer systems, and the string on
1224 older systems. Some functions (such as "aio_realpath") will always rely
1225 on the string form of the pathname.
1226
1227 So this functionality is mainly useful to get some protection against
1228 "chdir", to easily get an absolute path out of a relative path for
1229 future reference, and to speed up doing many operations in the same
1230 directory (e.g. when stat'ing all files in a directory).
1231
1232 The following functions implement this working directory abstraction:
1233
1234 aio_wd $pathname, $callback->($wd)
1235 Asynchonously canonicalise the given pathname and convert it to an
1236 IO::AIO::WD object representing it. If possible and supported on the
1237 system, also open a directory fd to speed up pathname resolution
1238 relative to this working directory.
1239
1240 If something goes wrong, then "undef" is passwd to the callback
1241 instead of a working directory object and $! is set appropriately.
1242 Since passing "undef" as working directory component of a pathname
1243 fails the request with "ENOENT", there is often no need for error
1244 checking in the "aio_wd" callback, as future requests using the
1245 value will fail in the expected way.
1246
1247 IO::AIO::CWD
1248 This is a compiletime constant (object) that represents the process
1249 current working directory.
1250
1251 Specifying this object as working directory object for a pathname is
1252 as if the pathname would be specified directly, without a directory
1253 object. For example, these calls are functionally identical:
1254
1255 aio_stat "somefile", sub { ... };
1256 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1257
1258 To recover the path associated with an IO::AIO::WD object, you can use
1259 "aio_realpath":
1260
1261 aio_realpath $wd, sub {
1262 warn "path is $_[0]\n";
1263 };
1264
1265 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1266 sometimes, fall back to using an absolue path.
894 1267
895 IO::AIO::REQ CLASS 1268 IO::AIO::REQ CLASS
896 All non-aggregate "aio_*" functions return an object of this class when 1269 All non-aggregate "aio_*" functions return an object of this class when
897 called in non-void context. 1270 called in non-void context.
898 1271
… …
998 Sets a feeder/generator on this group: every group can have an 1371 Sets a feeder/generator on this group: every group can have an
999 attached generator that generates requests if idle. The idea behind 1372 attached generator that generates requests if idle. The idea behind
1000 this is that, although you could just queue as many requests as you 1373 this is that, although you could just queue as many requests as you
1001 want in a group, this might starve other requests for a potentially 1374 want in a group, this might starve other requests for a potentially
1002 long time. For example, "aio_scandir" might generate hundreds of 1375 long time. For example, "aio_scandir" might generate hundreds of
1003 thousands "aio_stat" requests, delaying any later requests for a 1376 thousands of "aio_stat" requests, delaying any later requests for a
1004 long time. 1377 long time.
1005 1378
1006 To avoid this, and allow incremental generation of requests, you can 1379 To avoid this, and allow incremental generation of requests, you can
1007 instead a group and set a feeder on it that generates those 1380 instead a group and set a feeder on it that generates those
1008 requests. The feed callback will be called whenever there are few 1381 requests. The feed callback will be called whenever there are few
… …
1050 results. 1423 results.
1051 1424
1052 See "poll_cb" for an example. 1425 See "poll_cb" for an example.
1053 1426
1054 IO::AIO::poll_cb 1427 IO::AIO::poll_cb
1055 Process some outstanding events on the result pipe. You have to call 1428 Process some requests that have reached the result phase (i.e. they
1429 have been executed but the results are not yet reported). You have
1430 to call this "regularly" to finish outstanding requests.
1431
1056 this regularly. Returns 0 if all events could be processed (or there 1432 Returns 0 if all events could be processed (or there were no events
1057 were no events to process), or -1 if it returned earlier for 1433 to process), or -1 if it returned earlier for whatever reason.
1058 whatever reason. Returns immediately when no events are outstanding. 1434 Returns immediately when no events are outstanding. The amount of
1059 The amount of events processed depends on the settings of 1435 events processed depends on the settings of "IO::AIO::max_poll_req",
1060 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1436 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1061 1437
1062 If not all requests were processed for whatever reason, the 1438 If not all requests were processed for whatever reason, the poll
1063 filehandle will still be ready when "poll_cb" returns, so normally 1439 file descriptor will still be ready when "poll_cb" returns, so
1064 you don't have to do anything special to have it called later. 1440 normally you don't have to do anything special to have it called
1441 later.
1065 1442
1066 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1443 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1067 becomes ready, it can be beneficial to call this function from loops 1444 becomes ready, it can be beneficial to call this function from loops
1068 which submit a lot of requests, to make sure the results get 1445 which submit a lot of requests, to make sure the results get
1069 processed when they become available and not just when the loop is 1446 processed when they become available and not just when the loop is
… …
1077 Event->io (fd => IO::AIO::poll_fileno, 1454 Event->io (fd => IO::AIO::poll_fileno,
1078 poll => 'r', async => 1, 1455 poll => 'r', async => 1,
1079 cb => \&IO::AIO::poll_cb); 1456 cb => \&IO::AIO::poll_cb);
1080 1457
1081 IO::AIO::poll_wait 1458 IO::AIO::poll_wait
1082 If there are any outstanding requests and none of them in the result 1459 Wait until either at least one request is in the result phase or no
1083 phase, wait till the result filehandle becomes ready for reading 1460 requests are outstanding anymore.
1084 (simply does a "select" on the filehandle. This is useful if you 1461
1085 want to synchronously wait for some requests to finish). 1462 This is useful if you want to synchronously wait for some requests
1463 to become ready, without actually handling them.
1086 1464
1087 See "nreqs" for an example. 1465 See "nreqs" for an example.
1088 1466
1089 IO::AIO::poll 1467 IO::AIO::poll
1090 Waits until some requests have been handled. 1468 Waits until some requests have been handled.
… …
1099 1477
1100 Strictly equivalent to: 1478 Strictly equivalent to:
1101 1479
1102 IO::AIO::poll_wait, IO::AIO::poll_cb 1480 IO::AIO::poll_wait, IO::AIO::poll_cb
1103 while IO::AIO::nreqs; 1481 while IO::AIO::nreqs;
1482
1483 This function can be useful at program aborts, to make sure
1484 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1485 already calls this function on normal exits), or when you are merely
1486 using "IO::AIO" for its more advanced functions, rather than for
1487 async I/O, e.g.:
1488
1489 my ($dirs, $nondirs);
1490 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1491 IO::AIO::flush;
1492 # $dirs, $nondirs are now set
1104 1493
1105 IO::AIO::max_poll_reqs $nreqs 1494 IO::AIO::max_poll_reqs $nreqs
1106 IO::AIO::max_poll_time $seconds 1495 IO::AIO::max_poll_time $seconds
1107 These set the maximum number of requests (default 0, meaning 1496 These set the maximum number of requests (default 0, meaning
1108 infinity) that are being processed by "IO::AIO::poll_cb" in one 1497 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
1202 1591
1203 This is a very bad function to use in interactive programs because 1592 This is a very bad function to use in interactive programs because
1204 it blocks, and a bad way to reduce concurrency because it is 1593 it blocks, and a bad way to reduce concurrency because it is
1205 inexact: Better use an "aio_group" together with a feed callback. 1594 inexact: Better use an "aio_group" together with a feed callback.
1206 1595
1207 It's main use is in scripts without an event loop - when you want to 1596 Its main use is in scripts without an event loop - when you want to
1208 stat a lot of files, you can write somehting like this: 1597 stat a lot of files, you can write something like this:
1209 1598
1210 IO::AIO::max_outstanding 32; 1599 IO::AIO::max_outstanding 32;
1211 1600
1212 for my $path (...) { 1601 for my $path (...) {
1213 aio_stat $path , ...; 1602 aio_stat $path , ...;
… …
1242 1631
1243 IO::AIO::npending 1632 IO::AIO::npending
1244 Returns the number of requests currently in the pending state 1633 Returns the number of requests currently in the pending state
1245 (executed, but not yet processed by poll_cb). 1634 (executed, but not yet processed by poll_cb).
1246 1635
1636 SUBSECOND STAT TIME ACCESS
1637 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1638 generally find access/modification and change times with subsecond time
1639 accuracy of the system supports it, but perl's built-in functions only
1640 return the integer part.
1641
1642 The following functions return the timestamps of the most recent stat
1643 with subsecond precision on most systems and work both after
1644 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1645 value is only meaningful after a successful "stat"/"lstat" call, or
1646 during/after a successful "aio_stat"/"aio_lstat" callback.
1647
1648 This is similar to the Time::HiRes "stat" functions, but can return full
1649 resolution without rounding and work with standard perl "stat",
1650 alleviating the need to call the special "Time::HiRes" functions, which
1651 do not act like their perl counterparts.
1652
1653 On operating systems or file systems where subsecond time resolution is
1654 not supported or could not be detected, a fractional part of 0 is
1655 returned, so it is always safe to call these functions.
1656
1657 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1658 IO::AIO::st_btime
1659 Return the access, modication, change or birth time, respectively,
1660 including fractional part. Due to the limited precision of floating
1661 point, the accuracy on most platforms is only a bit better than
1662 milliseconds for times around now - see the *nsec* function family,
1663 below, for full accuracy.
1664
1665 File birth time is only available when the OS and perl support it
1666 (on FreeBSD and NetBSD at the time of this writing, although support
1667 is adaptive, so if your OS/perl gains support, IO::AIO can take
1668 advantage of it). On systems where it isn't available, 0 is
1669 currently returned, but this might change to "undef" in a future
1670 version.
1671
1672 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1673 Returns access, modification, change and birth time all in one go,
1674 and maybe more times in the future version.
1675
1676 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1677 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1678 Return the fractional access, modifcation, change or birth time, in
1679 nanoseconds, as an integer in the range 0 to 999999999.
1680
1681 Note that no accessors are provided for access, modification and
1682 change times - you need to get those from "stat _" if required ("int
1683 IO::AIO::st_atime" and so on will *not* generally give you the
1684 correct value).
1685
1686 $seconds = IO::AIO::st_btimesec
1687 The (integral) seconds part of the file birth time, if available.
1688
1689 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1690 Like the functions above, but returns all four times in one go (and
1691 maybe more in future versions).
1692
1693 $counter = IO::AIO::st_gen
1694 Returns the generation counter (in practice this is just a random
1695 number) of the file. This is only available on platforms which have
1696 this member in their "struct stat" (most BSDs at the time of this
1697 writing) and generally only to the root usert. If unsupported, 0 is
1698 returned, but this might change to "undef" in a future version.
1699
1700 Example: print the high resolution modification time of /etc, using
1701 "stat", and "IO::AIO::aio_stat".
1702
1703 if (stat "/etc") {
1704 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1705 }
1706
1707 IO::AIO::aio_stat "/etc", sub {
1708 $_[0]
1709 and return;
1710
1711 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1712 };
1713
1714 IO::AIO::flush;
1715
1716 Output of the awbove on my system, showing reduced and full accuracy:
1717
1718 stat(/etc) mtime: 1534043702.020808
1719 aio_stat(/etc) mtime: 1534043702.020807792
1720
1247 MISCELLANEOUS FUNCTIONS 1721 MISCELLANEOUS FUNCTIONS
1248 IO::AIO implements some functions that might be useful, but are not 1722 IO::AIO implements some functions that are useful when you want to use
1249 asynchronous. 1723 some "Advanced I/O" function not available to in Perl, without going the
1724 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1725 counterpart.
1726
1727 $numfd = IO::AIO::get_fdlimit
1728 This function is *EXPERIMENTAL* and subject to change.
1729
1730 Tries to find the current file descriptor limit and returns it, or
1731 "undef" and sets $! in case of an error. The limit is one larger
1732 than the highest valid file descriptor number.
1733
1734 IO::AIO::min_fdlimit [$numfd]
1735 This function is *EXPERIMENTAL* and subject to change.
1736
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.
1250 1750
1251 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1252 Calls the "eio_sendfile_sync" function, which is like 1752 Calls the "eio_sendfile_sync" function, which is like
1253 "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
1254 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
… …
1256 1756
1257 Returns the number of bytes copied, or -1 on error. 1757 Returns the number of bytes copied, or -1 on error.
1258 1758
1259 IO::AIO::fadvise $fh, $offset, $len, $advice 1759 IO::AIO::fadvise $fh, $offset, $len, $advice
1260 Simply calls the "posix_fadvise" function (see its manpage for 1760 Simply calls the "posix_fadvise" function (see its manpage for
1261 details). The following advice constants are avaiable: 1761 details). The following advice constants are available:
1262 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1762 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1263 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1763 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1264 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1764 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1265 1765
1266 On systems that do not implement "posix_fadvise", this function 1766 On systems that do not implement "posix_fadvise", this function
1267 returns ENOSYS, otherwise the return value of "posix_fadvise". 1767 returns ENOSYS, otherwise the return value of "posix_fadvise".
1268 1768
1269 IO::AIO::madvise $scalar, $offset, $len, $advice 1769 IO::AIO::madvise $scalar, $offset, $len, $advice
1270 Simply calls the "posix_madvise" function (see its manpage for 1770 Simply calls the "posix_madvise" function (see its manpage for
1271 details). The following advice constants are avaiable: 1771 details). The following advice constants are available:
1272 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1273 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1274 "IO::AIO::MADV_DONTNEED". 1774 "IO::AIO::MADV_DONTNEED".
1275 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
1276 On systems that do not implement "posix_madvise", this function 1780 On systems that do not implement "posix_madvise", this function
1277 returns ENOSYS, otherwise the return value of "posix_madvise". 1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1278 1782
1279 IO::AIO::mprotect $scalar, $offset, $len, $protect 1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1280 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1281 $scalar (see its manpage for details). The following protect 1785 $scalar (see its manpage for details). The following protect
1282 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1283 "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.
1284 1792
1285 On systems that do not implement "mprotect", this function returns 1793 On systems that do not implement "mprotect", this function returns
1286 ENOSYS, otherwise the return value of "mprotect". 1794 ENOSYS, otherwise the return value of "mprotect".
1287 1795
1288 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1289 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
1290 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.
1291 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
1292 The only operations allowed on the scalar are "substr"/"vec" that 1805 The only operations allowed on the mmapped scalar are
1293 don't change the string length, and most read-only operations such 1806 "substr"/"vec", which don't change the string length, and most
1294 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.
1295 1809
1296 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.
1297 1811
1298 The memory map associated with the $scalar is automatically removed 1812 The memory map associated with the $scalar is automatically removed
1299 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1813 when the $scalar is undef'd or destroyed, or when the
1300 "IO::AIO::munmap" functions are called. 1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1301 1815
1302 This calls the "mmap"(2) function internally. See your system's 1816 This calls the "mmap"(2) function internally. See your system's
1303 manual page for details on the $length, $prot and $flags parameters. 1817 manual page for details on the $length, $prot and $flags parameters.
1304 1818
1305 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
… …
1309 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1823 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1310 "IO::AIO::PROT_WRITE", 1824 "IO::AIO::PROT_WRITE",
1311 1825
1312 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1826 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1313 "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
1314 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
1315 (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",
1316 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1831 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1832 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1317 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1833 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1318 "IO::AIO::MAP_NONBLOCK" 1834 "IO::AIO::MAP_STACK".
1319 1835
1320 If $fh is "undef", then a file descriptor of -1 is passed. 1836 If $fh is "undef", then a file descriptor of -1 is passed.
1321 1837
1322 $offset is the offset from the start of the file - it generally must 1838 $offset is the offset from the start of the file - it generally must
1323 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1839 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1335 1851
1336 my $fast_md5 = md5 $data; 1852 my $fast_md5 = md5 $data;
1337 1853
1338 IO::AIO::munmap $scalar 1854 IO::AIO::munmap $scalar
1339 Removes a previous mmap and undefines the $scalar. 1855 Removes a previous mmap and undefines the $scalar.
1856
1857 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1858 $new_address = 0]
1859 Calls the Linux-specific mremap(2) system call. The $scalar must
1860 have been mapped by "IO::AIO::mmap", and $flags must currently
1861 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1862
1863 Returns true if successful, and false otherwise. If the underlying
1864 mmapped region has changed address, then the true value has the
1865 numerical value 1, otherwise it has the numerical value 0:
1866
1867 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1868 or die "mremap: $!";
1869
1870 if ($success*1) {
1871 warn "scalar has chanegd address in memory\n";
1872 }
1873
1874 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1875 implemented, but not supported and might go away in a future
1876 version.
1877
1878 On systems where this call is not supported or is not emulated, this
1879 call returns falls and sets $! to "ENOSYS".
1880
1881 IO::AIO::mlockall $flags
1882 Calls the "eio_mlockall_sync" function, which is like
1883 "aio_mlockall", but is blocking.
1340 1884
1341 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1885 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1342 Calls the "munlock" function, undoing the effects of a previous 1886 Calls the "munlock" function, undoing the effects of a previous
1343 "aio_mlock" call (see its description for details). 1887 "aio_mlock" call (see its description for details).
1344 1888
1345 IO::AIO::munlockall 1889 IO::AIO::munlockall
1346 Calls the "munlockall" function. 1890 Calls the "munlockall" function.
1347 1891
1348 On systems that do not implement "munlockall", this function returns 1892 On systems that do not implement "munlockall", this function returns
1349 ENOSYS, otherwise the return value of "munlockall". 1893 ENOSYS, otherwise the return value of "munlockall".
1894
1895 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1896 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1897 $w_off are "undef", then "NULL" is passed for these, otherwise they
1898 should be the file offset.
1899
1900 $r_fh and $w_fh should not refer to the same file, as splice might
1901 silently corrupt the data in this case.
1902
1903 The following symbol flag values are available:
1904 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1905 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1906
1907 See the splice(2) manpage for details.
1908
1909 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1910 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1911 description for "IO::AIO::splice" above for details.
1912
1913 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1914 Attempts to query or change the pipe buffer size. Obviously works
1915 only on pipes, and currently works only on GNU/Linux systems, and
1916 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1917 influence pipe buffer size on other systems, drop me a note.
1918
1919 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1920 This is a direct interface to the Linux pipe2(2) system call. If
1921 $flags is missing or 0, then this should be the same as a call to
1922 perl's built-in "pipe" function and create a new pipe, and works on
1923 systems that lack the pipe2 syscall. On win32, this case invokes
1924 "_pipe (..., 4096, O_BINARY)".
1925
1926 If $flags is non-zero, it tries to invoke the pipe2 system call with
1927 the given flags (Linux 2.6.27, glibc 2.9).
1928
1929 On success, the read and write file handles are returned.
1930
1931 On error, nothing will be returned. If the pipe2 syscall is missing
1932 and $flags is non-zero, fails with "ENOSYS".
1933
1934 Please refer to pipe2(2) for more info on the $flags, but at the
1935 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1936 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1937 supported.
1938
1939 Example: create a pipe race-free w.r.t. threads and fork:
1940
1941 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1942 or die "pipe2: $!\n";
1943
1944 $fh = IO::AIO::memfd_create $pathname[, $flags]
1945 This is a direct interface to the Linux memfd_create(2) system call.
1946 The (unhelpful) default for $flags is 0, but your default should be
1947 "IO::AIO::MFD_CLOEXEC".
1948
1949 On success, the new memfd filehandle is returned, otherwise returns
1950 "undef". If the memfd_create syscall is missing, fails with
1951 "ENOSYS".
1952
1953 Please refer to memfd_create(2) for more info on this call.
1954
1955 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1956 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1957
1958 Example: create a new memfd.
1959
1960 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1961 or die "m,emfd_create: $!\n";
1962 =item $fh = IO::AIO::eventfd [$initval, [$flags]]
1963
1964 This is a direct interface to the Linux eventfd(2) system call. The
1965 (unhelpful) defaults for $initval and $flags are 0 for both.
1966
1967 On success, the new eventfd filehandle is returned, otherwise
1968 returns "undef". If the eventfd syscall is missing, fails with
1969 "ENOSYS".
1970
1971 Please refer to eventfd(2) for more info on this call.
1972
1973 The following symbol flag values are available:
1974 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1975 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1976
1977 Example: create a new eventfd filehandle:
1978
1979 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
1980 or die "eventfd: $!\n";
1981
1982 $fh = IO::AIO::timerfd_create $clockid[, $flags]
1983 This is a direct interface to the Linux timerfd_create(2) system
1984 call. The (unhelpful) default for $flags is 0, but your default
1985 should be "IO::AIO::TFD_CLOEXEC".
1986
1987 On success, the new timerfd filehandle is returned, otherwise
1988 returns "undef". If the timerfd_create syscall is missing, fails
1989 with "ENOSYS".
1990
1991 Please refer to timerfd_create(2) for more info on this call.
1992
1993 The following $clockid values are available:
1994 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
1995 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
1996 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
1997 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
1998
1999 The following $flags values are available (Linux 2.6.27):
2000 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2001
2002 Example: create a new timerfd and set it to one-second repeated
2003 alarms, then wait for two alarms:
2004
2005 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2006 or die "timerfd_create: $!\n";
2007
2008 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2009 or die "timerfd_settime: $!\n";
2010
2011 for (1..2) {
2012 8 == sysread $fh, my $buf, 8
2013 or die "timerfd read failure\n";
2014
2015 printf "number of expirations (likely 1): %d\n",
2016 unpack "Q", $buf;
2017 }
2018
2019 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2020 $new_interval, $nbw_value
2021 This is a direct interface to the Linux timerfd_settime(2) system
2022 call. Please refer to its manpage for more info on this call.
2023
2024 The new itimerspec is specified using two (possibly fractional)
2025 second values, $new_interval and $new_value).
2026
2027 On success, the current interval and value are returned (as per
2028 "timerfd_gettime"). On failure, the empty list is returned.
2029
2030 The following $flags values are available:
2031 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2032
2033 See "IO::AIO::timerfd_create" for a full example.
2034
2035 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2036 This is a direct interface to the Linux timerfd_gettime(2) system
2037 call. Please refer to its manpage for more info on this call.
2038
2039 On success, returns the current values of interval and value for the
2040 given timerfd (as potentially fractional second values). On failure,
2041 the empty list is returned.
1350 2042
1351EVENT LOOP INTEGRATION 2043EVENT LOOP INTEGRATION
1352 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2044 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1353 automatically into many event loops: 2045 automatically into many event loops:
1354 2046
… …
1393 2085
1394 You might get around by not *using* IO::AIO before (or after) forking. 2086 You might get around by not *using* IO::AIO before (or after) forking.
1395 You could also try to call the IO::AIO::reinit function in the child: 2087 You could also try to call the IO::AIO::reinit function in the child:
1396 2088
1397 IO::AIO::reinit 2089 IO::AIO::reinit
1398 Abondons all current requests and I/O threads and simply 2090 Abandons all current requests and I/O threads and simply
1399 reinitialises all data structures. This is not an operation 2091 reinitialises all data structures. This is not an operation
1400 suppported by any standards, but happens to work on GNU/Linux and 2092 supported by any standards, but happens to work on GNU/Linux and
1401 some newer BSD systems. 2093 some newer BSD systems.
1402 2094
1403 The only reasonable use for this function is to call it after 2095 The only reasonable use for this function is to call it after
1404 forking, if "IO::AIO" was used in the parent. Calling it while 2096 forking, if "IO::AIO" was used in the parent. Calling it while
1405 IO::AIO is active in the process will result in undefined behaviour. 2097 IO::AIO is active in the process will result in undefined behaviour.
1406 Calling it at any time will also result in any undefined (by POSIX) 2098 Calling it at any time will also result in any undefined (by POSIX)
1407 behaviour. 2099 behaviour.
1408 2100
2101 LINUX-SPECIFIC CALLS
2102 When a call is documented as "linux-specific" then this means it
2103 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2104 availability and compatibility of such calls regardless of the platform
2105 it is compiled on, so platforms such as FreeBSD which often implement
2106 these calls will work. When in doubt, call them and see if they fail wth
2107 "ENOSYS".
2108
1409 MEMORY USAGE 2109 MEMORY USAGE
1410 Per-request usage: 2110 Per-request usage:
1411 2111
1412 Each aio request uses - depending on your architecture - around 100-200 2112 Each aio request uses - depending on your architecture - around 100-200
1413 bytes of memory. In addition, stat requests need a stat buffer (possibly 2113 bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
1423 In the execution phase, some aio requests require more memory for 2123 In the execution phase, some aio requests require more memory for
1424 temporary buffers, and each thread requires a stack and other data 2124 temporary buffers, and each thread requires a stack and other data
1425 structures (usually around 16k-128k, depending on the OS). 2125 structures (usually around 16k-128k, depending on the OS).
1426 2126
1427KNOWN BUGS 2127KNOWN BUGS
1428 Known bugs will be fixed in the next release. 2128 Known bugs will be fixed in the next release :)
2129
2130KNOWN ISSUES
2131 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2132 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2133 non-created hash slots or other scalars I didn't think of. It's best to
2134 avoid such and either use scalar variables or making sure that the
2135 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2136
2137 I am not sure anything can be done about this, so this is considered a
2138 known issue, rather than a bug.
1429 2139
1430SEE ALSO 2140SEE ALSO
1431 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2141 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1432 more natural syntax. 2142 more natural syntax.
1433 2143

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