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Revision 1.68 by root, Mon Sep 5 00:04:07 2022 UTC

1NAME 1NAME
2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous/Advanced Input/Output
3 3
4SYNOPSIS 4SYNOPSIS
5 use IO::AIO; 5 use IO::AIO;
6 6
7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
… …
55 not well-supported or restricted (GNU/Linux doesn't allow them on normal 55 not well-supported or restricted (GNU/Linux doesn't allow them on normal
56 files currently, for example), and they would only support aio_read and 56 files currently, for example), and they would only support aio_read and
57 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
58 using threads anyway. 58 using threads anyway.
59 59
60 In addition to asynchronous I/O, this module also exports some rather
61 arcane interfaces, such as "madvise" or linux's "splice" system call,
62 which is why the "A" in "AIO" can also mean *advanced*.
63
60 Although the module will work in the presence of other (Perl-) threads, 64 Although the module will work in the presence of other (Perl-) threads,
61 it is currently not reentrant in any way, so use appropriate locking 65 it is currently not reentrant in any way, so use appropriate locking
62 yourself, always call "poll_cb" from within the same thread, or never 66 yourself, always call "poll_cb" from within the same thread, or never
63 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
64 68
65 EXAMPLE 69 EXAMPLE
66 This is a simple example that uses the EV module and loads /etc/passwd 70 This is a simple example that uses the EV module and loads /etc/passwd
67 asynchronously: 71 asynchronously:
68 72
69 use Fcntl;
70 use EV; 73 use EV;
71 use IO::AIO; 74 use IO::AIO;
72 75
73 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
… …
91 94
92 # file contents now in $contents 95 # file contents now in $contents
93 print $contents; 96 print $contents;
94 97
95 # exit event loop and program 98 # exit event loop and program
96 EV::unloop; 99 EV::break;
97 }; 100 };
98 }; 101 };
99 102
100 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
101 # check for sockets etc. etc. 104 # check for sockets etc. etc.
102 105
103 # process events as long as there are some: 106 # process events as long as there are some:
104 EV::loop; 107 EV::run;
105 108
106REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
107 Every "aio_*" function creates a request. which is a C data structure 110 Every "aio_*" function creates a request. which is a C data structure
108 not directly visible to Perl. 111 not directly visible to Perl.
109 112
… …
146 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
147 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
148 151
149FUNCTIONS 152FUNCTIONS
150 QUICK OVERVIEW 153 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions 154 This section simply lists the prototypes most of the functions for quick
152 for quick reference. See the following sections for function-by-function 155 reference. See the following sections for function-by-function
153 documentation. 156 documentation.
154 157
158 aio_wd $pathname, $callback->($wd)
155 aio_open $pathname, $flags, $mode, $callback->($fh) 159 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status) 160 aio_close $fh, $callback->($status)
161 aio_seek $fh,$offset,$whence, $callback->($offs)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 162 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 163 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 164 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval) 165 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status) 166 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status) 167 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs) 168 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
171 aio_chmod $fh_or_path, $mode, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status) 172 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status) 173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168 aio_unlink $pathname, $callback->($status) 175 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status) 176 aio_mknod $pathname, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status) 177 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status) 178 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link) 179 aio_readlink $pathname, $callback->($link)
180 aio_realpath $pathname, $callback->($path)
173 aio_rename $srcpath, $dstpath, $callback->($status) 181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status) 183 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status) 184 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries) 185 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 188 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180 aio_load $path, $data, $callback->($status) 190 aio_load $pathname, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status) 191 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status) 192 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status) 193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
185 aio_sync $callback->($status) 196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
186 aio_fsync $fh, $callback->($status) 198 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status) 199 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status) 201 aio_pathsync $pathname, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status) 205 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...) 206 aio_group $callback->(...)
195 aio_nop $callback->() 207 aio_nop $callback->()
… …
209 IO::AIO::idle_timeout $seconds 221 IO::AIO::idle_timeout $seconds
210 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
211 IO::AIO::nreqs 223 IO::AIO::nreqs
212 IO::AIO::nready 224 IO::AIO::nready
213 IO::AIO::npending 225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
214 230
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count 231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice 232 IO::AIO::fadvise $fh, $offset, $len, $advice
233 IO::AIO::fexecve $fh, $argv, $envp
234
235 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
236 IO::AIO::munmap $scalar
237 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
217 IO::AIO::madvise $scalar, $offset, $length, $advice 238 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect 239 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef 240 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall 241 IO::AIO::munlockall
221 242
222 AIO REQUEST FUNCTIONS 243 # stat extensions
244 $counter = IO::AIO::st_gen
245 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
246 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
247 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
248 $seconds = IO::AIO::st_btimesec
249 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
250
251 # very much unportable syscalls
252 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
253 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
254 IO::AIO::tee $r_fh, $w_fh, $length, $flags
255
256 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
257 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
258
259 $fh = IO::AIO::eventfd [$initval, [$flags]]
260 $fh = IO::AIO::memfd_create $pathname[, $flags]
261
262 $fh = IO::AIO::timerfd_create $clockid[, $flags]
263 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
264 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
265
266 $fh = IO::AIO::pidfd_open $pid[, $flags]
267 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
268 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
269
270 API NOTES
223 All the "aio_*" calls are more or less thin wrappers around the syscall 271 All the "aio_*" calls are more or less thin wrappers around the syscall
224 with the same name (sans "aio_"). The arguments are similar or 272 with the same name (sans "aio_"). The arguments are similar or
225 identical, and they all accept an additional (and optional) $callback 273 identical, and they all accept an additional (and optional) $callback
226 argument which must be a code reference. This code reference will get 274 argument which must be a code reference. This code reference will be
227 called with the syscall return code (e.g. most syscalls return -1 on
228 error, unlike perl, which usually delivers "false") as its sole argument
229 after the given syscall has been executed asynchronously. 275 called after the syscall has been executed in an asynchronous fashion.
276 The results of the request will be passed as arguments to the callback
277 (and, if an error occured, in $!) - for most requests the syscall return
278 code (e.g. most syscalls return -1 on error, unlike perl, which usually
279 delivers "false").
280
281 Some requests (such as "aio_readdir") pass the actual results and
282 communicate failures by passing "undef".
230 283
231 All functions expecting a filehandle keep a copy of the filehandle 284 All functions expecting a filehandle keep a copy of the filehandle
232 internally until the request has finished. 285 internally until the request has finished.
233 286
234 All functions return request objects of type IO::AIO::REQ that allow 287 All functions return request objects of type IO::AIO::REQ that allow
235 further manipulation of those requests while they are in-flight. 288 further manipulation of those requests while they are in-flight.
236 289
237 The pathnames you pass to these routines *must* be absolute and encoded 290 The pathnames you pass to these routines *should* be absolute. The
238 as octets. The reason for the former is that at the time the request is 291 reason for this is that at the time the request is being executed, the
239 being executed, the current working directory could have changed. 292 current working directory could have changed. Alternatively, you can
240 Alternatively, you can make sure that you never change the current 293 make sure that you never change the current working directory anywhere
241 working directory anywhere in the program and then use relative paths. 294 in the program and then use relative paths. You can also take advantage
295 of IO::AIOs working directory abstraction, that lets you specify paths
296 relative to some previously-opened "working directory object" - see the
297 description of the "IO::AIO::WD" class later in this document.
242 298
243 To encode pathnames as octets, either make sure you either: a) always 299 To encode pathnames as octets, either make sure you either: a) always
244 pass in filenames you got from outside (command line, readdir etc.) 300 pass in filenames you got from outside (command line, readdir etc.)
245 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 301 without tinkering, b) are in your native filesystem encoding, c) use the
246 and encode your pathnames to the locale (or other) encoding in effect in 302 Encode module and encode your pathnames to the locale (or other)
247 the user environment, d) use Glib::filename_from_unicode on unicode 303 encoding in effect in the user environment, d) use
248 filenames or e) use something else to ensure your scalar has the correct 304 Glib::filename_from_unicode on unicode filenames or e) use something
249 contents. 305 else to ensure your scalar has the correct contents.
250 306
251 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 307 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
252 handles correctly whether it is set or not. 308 handles correctly whether it is set or not.
253 309
310 AIO REQUEST FUNCTIONS
254 $prev_pri = aioreq_pri [$pri] 311 $prev_pri = aioreq_pri [$pri]
255 Returns the priority value that would be used for the next request 312 Returns the priority value that would be used for the next request
256 and, if $pri is given, sets the priority for the next aio request. 313 and, if $pri is given, sets the priority for the next aio request.
257 314
258 The default priority is 0, the minimum and maximum priorities are -4 315 The default priority is 0, the minimum and maximum priorities are -4
… …
280 Similar to "aioreq_pri", but subtracts the given value from the 337 Similar to "aioreq_pri", but subtracts the given value from the
281 current priority, so the effect is cumulative. 338 current priority, so the effect is cumulative.
282 339
283 aio_open $pathname, $flags, $mode, $callback->($fh) 340 aio_open $pathname, $flags, $mode, $callback->($fh)
284 Asynchronously open or create a file and call the callback with a 341 Asynchronously open or create a file and call the callback with a
285 newly created filehandle for the file. 342 newly created filehandle for the file (or "undef" in case of an
343 error).
286 344
287 The pathname passed to "aio_open" must be absolute. See API NOTES, 345 The pathname passed to "aio_open" must be absolute. See API NOTES,
288 above, for an explanation. 346 above, for an explanation.
289 347
290 The $flags argument is a bitmask. See the "Fcntl" module for a list. 348 The $flags argument is a bitmask. See the "Fcntl" module for a list.
… …
313 "O_APPEND"), the following POSIX and non-POSIX constants are 371 "O_APPEND"), the following POSIX and non-POSIX constants are
314 available (missing ones on your system are, as usual, 0): 372 available (missing ones on your system are, as usual, 0):
315 373
316 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", 374 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
317 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", 375 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
318 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". 376 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
377 and "O_ACCMODE".
319 378
320 aio_close $fh, $callback->($status) 379 aio_close $fh, $callback->($status)
321 Asynchronously close a file and call the callback with the result 380 Asynchronously close a file and call the callback with the result
322 code. 381 code.
323 382
… …
329 will use dup2 to overwrite the file descriptor with the write-end of 388 will use dup2 to overwrite the file descriptor with the write-end of
330 a pipe (the pipe fd will be created on demand and will be cached). 389 a pipe (the pipe fd will be created on demand and will be cached).
331 390
332 Or in other words: the file descriptor will be closed, but it will 391 Or in other words: the file descriptor will be closed, but it will
333 not be free for reuse until the perl filehandle is closed. 392 not be free for reuse until the perl filehandle is closed.
393
394 aio_seek $fh, $offset, $whence, $callback->($offs)
395 Seeks the filehandle to the new $offset, similarly to perl's
396 "sysseek". The $whence can use the traditional values (0 for
397 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
398 "IO::AIO::SEEK_END").
399
400 The resulting absolute offset will be passed to the callback, or -1
401 in case of an error.
402
403 In theory, the $whence constants could be different than the
404 corresponding values from Fcntl, but perl guarantees they are the
405 same, so don't panic.
406
407 As a GNU/Linux (and maybe Solaris) extension, also the constants
408 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
409 could be found. No guarantees about suitability for use in
410 "aio_seek" or Perl's "sysseek" can be made though, although I would
411 naively assume they "just work".
334 412
335 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 413 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
336 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 414 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
337 Reads or writes $length bytes from or to the specified $fh and 415 Reads or writes $length bytes from or to the specified $fh and
338 $offset into the scalar given by $data and offset $dataoffset and 416 $offset into the scalar given by $data and offset $dataoffset and
339 calls the callback without the actual number of bytes read (or -1 on 417 calls the callback with the actual number of bytes transferred (or
340 error, just like the syscall). 418 -1 on error, just like the syscall).
341 419
342 "aio_read" will, like "sysread", shrink or grow the $data scalar to 420 "aio_read" will, like "sysread", shrink or grow the $data scalar to
343 offset plus the actual number of bytes read. 421 offset plus the actual number of bytes read.
344 422
345 If $offset is undefined, then the current file descriptor offset 423 If $offset is undefined, then the current file descriptor offset
… …
402 As native sendfile syscalls (as practically any non-POSIX interface 480 As native sendfile syscalls (as practically any non-POSIX interface
403 hacked together in a hurry to improve benchmark numbers) tend to be 481 hacked together in a hurry to improve benchmark numbers) tend to be
404 rather buggy on many systems, this implementation tries to work 482 rather buggy on many systems, this implementation tries to work
405 around some known bugs in Linux and FreeBSD kernels (probably 483 around some known bugs in Linux and FreeBSD kernels (probably
406 others, too), but that might fail, so you really really should check 484 others, too), but that might fail, so you really really should check
407 the return value of "aio_sendfile" - fewre bytes than expected might 485 the return value of "aio_sendfile" - fewer bytes than expected might
408 have been transferred. 486 have been transferred.
409 487
410 aio_readahead $fh,$offset,$length, $callback->($retval) 488 aio_readahead $fh,$offset,$length, $callback->($retval)
411 "aio_readahead" populates the page cache with data from a file so 489 "aio_readahead" populates the page cache with data from a file so
412 that subsequent reads from that file will not block on disk I/O. The 490 that subsequent reads from that file will not block on disk I/O. The
… …
416 to a page boundary and bytes are read up to the next page boundary 494 to a page boundary and bytes are read up to the next page boundary
417 greater than or equal to (off-set+length). "aio_readahead" does not 495 greater than or equal to (off-set+length). "aio_readahead" does not
418 read beyond the end of the file. The current file offset of the file 496 read beyond the end of the file. The current file offset of the file
419 is left unchanged. 497 is left unchanged.
420 498
421 If that syscall doesn't exist (likely if your OS isn't Linux) it 499 If that syscall doesn't exist (likely if your kernel isn't Linux) it
422 will be emulated by simply reading the data, which would have a 500 will be emulated by simply reading the data, which would have a
423 similar effect. 501 similar effect.
424 502
425 aio_stat $fh_or_path, $callback->($status) 503 aio_stat $fh_or_path, $callback->($status)
426 aio_lstat $fh, $callback->($status) 504 aio_lstat $fh, $callback->($status)
427 Works like perl's "stat" or "lstat" in void context. The callback 505 Works almost exactly like perl's "stat" or "lstat" in void context.
428 will be called after the stat and the results will be available 506 The callback will be called after the stat and the results will be
429 using "stat _" or "-s _" etc... 507 available using "stat _" or "-s _" and other tests (with the
508 exception of "-B" and "-T").
430 509
431 The pathname passed to "aio_stat" must be absolute. See API NOTES, 510 The pathname passed to "aio_stat" must be absolute. See API NOTES,
432 above, for an explanation. 511 above, for an explanation.
433 512
434 Currently, the stats are always 64-bit-stats, i.e. instead of 513 Currently, the stats are always 64-bit-stats, i.e. instead of
… …
442 back on traditional behaviour). 521 back on traditional behaviour).
443 522
444 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", 523 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
445 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", 524 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
446 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". 525 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
526
527 To access higher resolution stat timestamps, see "SUBSECOND STAT
528 TIME ACCESS".
447 529
448 Example: Print the length of /etc/passwd: 530 Example: Print the length of /etc/passwd:
449 531
450 aio_stat "/etc/passwd", sub { 532 aio_stat "/etc/passwd", sub {
451 $_[0] and die "stat failed: $!"; 533 $_[0] and die "stat failed: $!";
… …
498 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 580 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
499 Works like perl's "utime" function (including the special case of 581 Works like perl's "utime" function (including the special case of
500 $atime and $mtime being undef). Fractional times are supported if 582 $atime and $mtime being undef). Fractional times are supported if
501 the underlying syscalls support them. 583 the underlying syscalls support them.
502 584
503 When called with a pathname, uses utimes(2) if available, otherwise 585 When called with a pathname, uses utimensat(2) or utimes(2) if
504 utime(2). If called on a file descriptor, uses futimes(2) if 586 available, otherwise utime(2). If called on a file descriptor, uses
505 available, otherwise returns ENOSYS, so this is not portable. 587 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
588 this is not portable.
506 589
507 Examples: 590 Examples:
508 591
509 # set atime and mtime to current time (basically touch(1)): 592 # set atime and mtime to current time (basically touch(1)):
510 aio_utime "path", undef, undef; 593 aio_utime "path", undef, undef;
… …
524 aio_chown "path", 0, undef; 607 aio_chown "path", 0, undef;
525 608
526 aio_truncate $fh_or_path, $offset, $callback->($status) 609 aio_truncate $fh_or_path, $offset, $callback->($status)
527 Works like truncate(2) or ftruncate(2). 610 Works like truncate(2) or ftruncate(2).
528 611
612 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
613 Allocates or frees disk space according to the $mode argument. See
614 the linux "fallocate" documentation for details.
615
616 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
617 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
618 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
619
620 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
621 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
622 "FALLOC_FL_INSERT_RANGE" to insert a range and
623 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
624 fallocate(2) manpage).
625
626 The file system block size used by "fallocate" is presumably the
627 "f_bsize" returned by "statvfs", but different filesystems and
628 filetypes can dictate other limitations.
629
630 If "fallocate" isn't available or cannot be emulated (currently no
631 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
632
529 aio_chmod $fh_or_path, $mode, $callback->($status) 633 aio_chmod $fh_or_path, $mode, $callback->($status)
530 Works like perl's "chmod" function. 634 Works like perl's "chmod" function.
531 635
532 aio_unlink $pathname, $callback->($status) 636 aio_unlink $pathname, $callback->($status)
533 Asynchronously unlink (delete) a file and call the callback with the 637 Asynchronously unlink (delete) a file and call the callback with the
534 result code. 638 result code.
535 639
536 aio_mknod $path, $mode, $dev, $callback->($status) 640 aio_mknod $pathname, $mode, $dev, $callback->($status)
537 [EXPERIMENTAL] 641 [EXPERIMENTAL]
538 642
539 Asynchronously create a device node (or fifo). See mknod(2). 643 Asynchronously create a device node (or fifo). See mknod(2).
540 644
541 The only (POSIX-) portable way of calling this function is: 645 The only (POSIX-) portable way of calling this function is:
542 646
543 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 647 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
544 648
545 See "aio_stat" for info about some potentially helpful extra 649 See "aio_stat" for info about some potentially helpful extra
546 constants and functions. 650 constants and functions.
547 651
548 aio_link $srcpath, $dstpath, $callback->($status) 652 aio_link $srcpath, $dstpath, $callback->($status)
… …
552 aio_symlink $srcpath, $dstpath, $callback->($status) 656 aio_symlink $srcpath, $dstpath, $callback->($status)
553 Asynchronously create a new symbolic link to the existing object at 657 Asynchronously create a new symbolic link to the existing object at
554 $srcpath at the path $dstpath and call the callback with the result 658 $srcpath at the path $dstpath and call the callback with the result
555 code. 659 code.
556 660
557 aio_readlink $path, $callback->($link) 661 aio_readlink $pathname, $callback->($link)
558 Asynchronously read the symlink specified by $path and pass it to 662 Asynchronously read the symlink specified by $path and pass it to
559 the callback. If an error occurs, nothing or undef gets passed to 663 the callback. If an error occurs, nothing or undef gets passed to
560 the callback. 664 the callback.
561 665
666 aio_realpath $pathname, $callback->($path)
667 Asynchronously make the path absolute and resolve any symlinks in
668 $path. The resulting path only consists of directories (same as
669 Cwd::realpath).
670
671 This request can be used to get the absolute path of the current
672 working directory by passing it a path of . (a single dot).
673
562 aio_rename $srcpath, $dstpath, $callback->($status) 674 aio_rename $srcpath, $dstpath, $callback->($status)
563 Asynchronously rename the object at $srcpath to $dstpath, just as 675 Asynchronously rename the object at $srcpath to $dstpath, just as
564 rename(2) and call the callback with the result code. 676 rename(2) and call the callback with the result code.
677
678 On systems that support the AIO::WD working directory abstraction
679 natively, the case "[$wd, "."]" as $srcpath is specialcased -
680 instead of failing, "rename" is called on the absolute path of $wd.
681
682 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
683 Basically a version of "aio_rename" with an additional $flags
684 argument. Calling this with "$flags=0" is the same as calling
685 "aio_rename".
686
687 Non-zero flags are currently only supported on GNU/Linux systems
688 that support renameat2. Other systems fail with "ENOSYS" in this
689 case.
690
691 The following constants are available (missing ones are, as usual
692 0), see renameat2(2) for details:
693
694 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
695 "IO::AIO::RENAME_WHITEOUT".
565 696
566 aio_mkdir $pathname, $mode, $callback->($status) 697 aio_mkdir $pathname, $mode, $callback->($status)
567 Asynchronously mkdir (create) a directory and call the callback with 698 Asynchronously mkdir (create) a directory and call the callback with
568 the result code. $mode will be modified by the umask at the time the 699 the result code. $mode will be modified by the umask at the time the
569 request is executed, so do not change your umask. 700 request is executed, so do not change your umask.
570 701
571 aio_rmdir $pathname, $callback->($status) 702 aio_rmdir $pathname, $callback->($status)
572 Asynchronously rmdir (delete) a directory and call the callback with 703 Asynchronously rmdir (delete) a directory and call the callback with
573 the result code. 704 the result code.
574 705
706 On systems that support the AIO::WD working directory abstraction
707 natively, the case "[$wd, "."]" is specialcased - instead of
708 failing, "rmdir" is called on the absolute path of $wd.
709
575 aio_readdir $pathname, $callback->($entries) 710 aio_readdir $pathname, $callback->($entries)
576 Unlike the POSIX call of the same name, "aio_readdir" reads an 711 Unlike the POSIX call of the same name, "aio_readdir" reads an
577 entire directory (i.e. opendir + readdir + closedir). The entries 712 entire directory (i.e. opendir + readdir + closedir). The entries
578 will not be sorted, and will NOT include the "." and ".." entries. 713 will not be sorted, and will NOT include the "." and ".." entries.
579 714
580 The callback is passed a single argument which is either "undef" or 715 The callback is passed a single argument which is either "undef" or
581 an array-ref with the filenames. 716 an array-ref with the filenames.
582 717
583 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 718 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
584 Quite similar to "aio_readdir", but the $flags argument allows to 719 Quite similar to "aio_readdir", but the $flags argument allows one
585 tune behaviour and output format. In case of an error, $entries will 720 to tune behaviour and output format. In case of an error, $entries
586 be "undef". 721 will be "undef".
587 722
588 The flags are a combination of the following constants, ORed 723 The flags are a combination of the following constants, ORed
589 together (the flags will also be passed to the callback, possibly 724 together (the flags will also be passed to the callback, possibly
590 modified): 725 modified):
591 726
592 IO::AIO::READDIR_DENTS 727 IO::AIO::READDIR_DENTS
593 When this flag is off, then the callback gets an arrayref 728 Normally the callback gets an arrayref consisting of names only
594 consisting of names only (as with "aio_readdir"), otherwise it 729 (as with "aio_readdir"). If this flag is set, then the callback
595 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each 730 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
596 describing a single directory entry in more detail. 731 describing a single directory entry in more detail:
597 732
598 $name is the name of the entry. 733 $name is the name of the entry.
599 734
600 $type is one of the "IO::AIO::DT_xxx" constants: 735 $type is one of the "IO::AIO::DT_xxx" constants:
601 736
602 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 737 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
603 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 738 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
604 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 739 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
605 740
606 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 741 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
607 you need to know, you have to run stat yourself. Also, for speed 742 you need to know, you have to run stat yourself. Also, for
608 reasons, the $type scalars are read-only: you can not modify 743 speed/memory reasons, the $type scalars are read-only: you must
609 them. 744 not modify them.
610 745
611 $inode is the inode number (which might not be exact on systems 746 $inode is the inode number (which might not be exact on systems
612 with 64 bit inode numbers and 32 bit perls). This field has 747 with 64 bit inode numbers and 32 bit perls). This field has
613 unspecified content on systems that do not deliver the inode 748 unspecified content on systems that do not deliver the inode
614 information. 749 information.
… …
626 of which names with short names are tried first. 761 of which names with short names are tried first.
627 762
628 IO::AIO::READDIR_STAT_ORDER 763 IO::AIO::READDIR_STAT_ORDER
629 When this flag is set, then the names will be returned in an 764 When this flag is set, then the names will be returned in an
630 order suitable for stat()'ing each one. That is, when you plan 765 order suitable for stat()'ing each one. That is, when you plan
631 to stat() all files in the given directory, then the returned 766 to stat() most or all files in the given directory, then the
632 order will likely be fastest. 767 returned order will likely be faster.
633 768
634 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 769 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
635 specified, then the likely dirs come first, resulting in a less 770 specified, then the likely dirs come first, resulting in a less
636 optimal stat order. 771 optimal stat order for stat'ing all entries, but likely a more
772 optimal order for finding subdirectories.
637 773
638 IO::AIO::READDIR_FOUND_UNKNOWN 774 IO::AIO::READDIR_FOUND_UNKNOWN
639 This flag should not be set when calling "aio_readdirx". 775 This flag should not be set when calling "aio_readdirx".
640 Instead, it is being set by "aio_readdirx", when any of the 776 Instead, it is being set by "aio_readdirx", when any of the
641 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 777 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
642 flag therefore indicates that all $type's are known, which can 778 flag therefore indicates that all $type's are known, which can
643 be used to speed up some algorithms. 779 be used to speed up some algorithms.
644 780
781 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
782 Opens, reads and closes the given file. The data is put into $data,
783 which is resized as required.
784
785 If $offset is negative, then it is counted from the end of the file.
786
787 If $length is zero, then the remaining length of the file is used.
788 Also, in this case, the same limitations to modifying $data apply as
789 when IO::AIO::mmap is used, i.e. it must only be modified in-place
790 with "substr". If the size of the file is known, specifying a
791 non-zero $length results in a performance advantage.
792
793 This request is similar to the older "aio_load" request, but since
794 it is a single request, it might be more efficient to use.
795
796 Example: load /etc/passwd into $passwd.
797
798 my $passwd;
799 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
800 $_[0] >= 0
801 or die "/etc/passwd: $!\n";
802
803 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
804 print $passwd;
805 };
806 IO::AIO::flush;
807
645 aio_load $path, $data, $callback->($status) 808 aio_load $pathname, $data, $callback->($status)
646 This is a composite request that tries to fully load the given file 809 This is a composite request that tries to fully load the given file
647 into memory. Status is the same as with aio_read. 810 into memory. Status is the same as with aio_read.
811
812 Using "aio_slurp" might be more efficient, as it is a single
813 request.
648 814
649 aio_copy $srcpath, $dstpath, $callback->($status) 815 aio_copy $srcpath, $dstpath, $callback->($status)
650 Try to copy the *file* (directories not supported as either source 816 Try to copy the *file* (directories not supported as either source
651 or destination) from $srcpath to $dstpath and call the callback with 817 or destination) from $srcpath to $dstpath and call the callback with
652 a status of 0 (ok) or -1 (error, see $!). 818 a status of 0 (ok) or -1 (error, see $!).
653 819
820 Existing destination files will be truncated.
821
654 This is a composite request that creates the destination file with 822 This is a composite request that creates the destination file with
655 mode 0200 and copies the contents of the source file into it using 823 mode 0200 and copies the contents of the source file into it using
656 "aio_sendfile", followed by restoring atime, mtime, access mode and 824 "aio_sendfile", followed by restoring atime, mtime, access mode and
657 uid/gid, in that order. 825 uid/gid, in that order.
658 826
… …
667 835
668 This is a composite request that tries to rename(2) the file first; 836 This is a composite request that tries to rename(2) the file first;
669 if rename fails with "EXDEV", it copies the file with "aio_copy" 837 if rename fails with "EXDEV", it copies the file with "aio_copy"
670 and, if that is successful, unlinks the $srcpath. 838 and, if that is successful, unlinks the $srcpath.
671 839
672 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 840 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
673 Scans a directory (similar to "aio_readdir") but additionally tries 841 Scans a directory (similar to "aio_readdir") but additionally tries
674 to efficiently separate the entries of directory $path into two sets 842 to efficiently separate the entries of directory $path into two sets
675 of names, directories you can recurse into (directories), and ones 843 of names, directories you can recurse into (directories), and ones
676 you cannot recurse into (everything else, including symlinks to 844 you cannot recurse into (everything else, including symlinks to
677 directories). 845 directories).
678 846
679 "aio_scandir" is a composite request that creates of many sub 847 "aio_scandir" is a composite request that generates many sub
680 requests_ $maxreq specifies the maximum number of outstanding aio 848 requests. $maxreq specifies the maximum number of outstanding aio
681 requests that this function generates. If it is "<= 0", then a 849 requests that this function generates. If it is "<= 0", then a
682 suitable default will be chosen (currently 4). 850 suitable default will be chosen (currently 4).
683 851
684 On error, the callback is called without arguments, otherwise it 852 On error, the callback is called without arguments, otherwise it
685 receives two array-refs with path-relative entry names. 853 receives two array-refs with path-relative entry names.
… …
710 Then entries will be sorted into likely directories a non-initial 878 Then entries will be sorted into likely directories a non-initial
711 dot currently) and likely non-directories (see "aio_readdirx"). Then 879 dot currently) and likely non-directories (see "aio_readdirx"). Then
712 every entry plus an appended "/." will be "stat"'ed, likely 880 every entry plus an appended "/." will be "stat"'ed, likely
713 directories first, in order of their inode numbers. If that 881 directories first, in order of their inode numbers. If that
714 succeeds, it assumes that the entry is a directory or a symlink to 882 succeeds, it assumes that the entry is a directory or a symlink to
715 directory (which will be checked seperately). This is often faster 883 directory (which will be checked separately). This is often faster
716 than stat'ing the entry itself because filesystems might detect the 884 than stat'ing the entry itself because filesystems might detect the
717 type of the entry without reading the inode data (e.g. ext2fs 885 type of the entry without reading the inode data (e.g. ext2fs
718 filetype feature), even on systems that cannot return the filetype 886 filetype feature), even on systems that cannot return the filetype
719 information on readdir. 887 information on readdir.
720 888
… …
726 894
727 It will also likely work on non-POSIX filesystems with reduced 895 It will also likely work on non-POSIX filesystems with reduced
728 efficiency as those tend to return 0 or 1 as link counts, which 896 efficiency as those tend to return 0 or 1 as link counts, which
729 disables the directory counting heuristic. 897 disables the directory counting heuristic.
730 898
731 aio_rmtree $path, $callback->($status) 899 aio_rmtree $pathname, $callback->($status)
732 Delete a directory tree starting (and including) $path, return the 900 Delete a directory tree starting (and including) $path, return the
733 status of the final "rmdir" only. This is a composite request that 901 status of the final "rmdir" only. This is a composite request that
734 uses "aio_scandir" to recurse into and rmdir directories, and unlink 902 uses "aio_scandir" to recurse into and rmdir directories, and unlink
735 everything else. 903 everything else.
736 904
905 aio_fcntl $fh, $cmd, $arg, $callback->($status)
906 aio_ioctl $fh, $request, $buf, $callback->($status)
907 These work just like the "fcntl" and "ioctl" built-in functions,
908 except they execute asynchronously and pass the return value to the
909 callback.
910
911 Both calls can be used for a lot of things, some of which make more
912 sense to run asynchronously in their own thread, while some others
913 make less sense. For example, calls that block waiting for external
914 events, such as locking, will also lock down an I/O thread while it
915 is waiting, which can deadlock the whole I/O system. At the same
916 time, there might be no alternative to using a thread to wait.
917
918 So in general, you should only use these calls for things that do
919 (filesystem) I/O, not for things that wait for other events
920 (network, other processes), although if you are careful and know
921 what you are doing, you still can.
922
923 The following constants are available and can be used for normal
924 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
925
926 "F_DUPFD_CLOEXEC",
927
928 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
929
930 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
931 "FIDEDUPERANGE".
932
933 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
934 "F_SEAL_GROW" and "F_SEAL_WRITE".
935
936 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
937 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
938
939 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
940 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
941 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
942
943 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
944 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
945 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
946 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
947 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
948
949 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
950 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
951 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
952 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
953 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
954 "FS_XFLAG_HASATTR",
955
737 aio_sync $callback->($status) 956 aio_sync $callback->($status)
738 Asynchronously call sync and call the callback when finished. 957 Asynchronously call sync and call the callback when finished.
739 958
740 aio_fsync $fh, $callback->($status) 959 aio_fsync $fh, $callback->($status)
741 Asynchronously call fsync on the given filehandle and call the 960 Asynchronously call fsync on the given filehandle and call the
… …
745 Asynchronously call fdatasync on the given filehandle and call the 964 Asynchronously call fdatasync on the given filehandle and call the
746 callback with the fdatasync result code. 965 callback with the fdatasync result code.
747 966
748 If this call isn't available because your OS lacks it or it couldn't 967 If this call isn't available because your OS lacks it or it couldn't
749 be detected, it will be emulated by calling "fsync" instead. 968 be detected, it will be emulated by calling "fsync" instead.
969
970 aio_syncfs $fh, $callback->($status)
971 Asynchronously call the syncfs syscall to sync the filesystem
972 associated to the given filehandle and call the callback with the
973 syncfs result code. If syncfs is not available, calls sync(), but
974 returns -1 and sets errno to "ENOSYS" nevertheless.
750 975
751 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 976 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
752 Sync the data portion of the file specified by $offset and $length 977 Sync the data portion of the file specified by $offset and $length
753 to disk (but NOT the metadata), by calling the Linux-specific 978 to disk (but NOT the metadata), by calling the Linux-specific
754 sync_file_range call. If sync_file_range is not available or it 979 sync_file_range call. If sync_file_range is not available or it
… …
758 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 983 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
759 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 984 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
760 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 985 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
761 manpage for details. 986 manpage for details.
762 987
763 aio_pathsync $path, $callback->($status) 988 aio_pathsync $pathname, $callback->($status)
764 This request tries to open, fsync and close the given path. This is 989 This request tries to open, fsync and close the given path. This is
765 a composite request intended to sync directories after directory 990 a composite request intended to sync directories after directory
766 operations (E.g. rename). This might not work on all operating 991 operations (E.g. rename). This might not work on all operating
767 systems or have any specific effect, but usually it makes sure that 992 systems or have any specific effect, but usually it makes sure that
768 directory changes get written to disc. It works for anything that 993 directory changes get written to disc. It works for anything that
… …
771 Future versions of this function might fall back to other methods 996 Future versions of this function might fall back to other methods
772 when "fsync" on the directory fails (such as calling "sync"). 997 when "fsync" on the directory fails (such as calling "sync").
773 998
774 Passes 0 when everything went ok, and -1 on error. 999 Passes 0 when everything went ok, and -1 on error.
775 1000
776 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 1001 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
777 $callback->($status) 1002 $callback->($status)
778 This is a rather advanced IO::AIO call, which only works on 1003 This is a rather advanced IO::AIO call, which only works on
779 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 1004 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
780 also works on data scalars managed by the Sys::Mmap or Mmap modules, 1005 also works on data scalars managed by the Sys::Mmap or Mmap modules,
781 note that the scalar must only be modified in-place while an aio 1006 note that the scalar must only be modified in-place while an aio
… …
783 1008
784 It calls the "msync" function of your OS, if available, with the 1009 It calls the "msync" function of your OS, if available, with the
785 memory area starting at $offset in the string and ending $length 1010 memory area starting at $offset in the string and ending $length
786 bytes later. If $length is negative, counts from the end, and if 1011 bytes later. If $length is negative, counts from the end, and if
787 $length is "undef", then it goes till the end of the string. The 1012 $length is "undef", then it goes till the end of the string. The
788 flags can be a combination of "IO::AIO::MS_ASYNC", 1013 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
789 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 1014 an optional "IO::AIO::MS_INVALIDATE".
790 1015
791 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 1016 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
792 $callback->($status) 1017 $callback->($status)
793 This is a rather advanced IO::AIO call, which works best on 1018 This is a rather advanced IO::AIO call, which works best on
794 mmap(2)ed scalars. 1019 mmap(2)ed scalars.
795 1020
796 It touches (reads or writes) all memory pages in the specified range 1021 It touches (reads or writes) all memory pages in the specified range
797 inside the scalar. All caveats and parameters are the same as for 1022 inside the scalar. All caveats and parameters are the same as for
798 "aio_msync", above, except for flags, which must be either 0 (which 1023 "aio_msync", above, except for flags, which must be either 0 (which
799 reads all pages and ensures they are instantiated) or 1024 reads all pages and ensures they are instantiated) or
800 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 1025 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
801 and writing an octet from it, which dirties the page). 1026 and writing an octet from it, which dirties the page).
802 1027
803 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1028 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
804 This is a rather advanced IO::AIO call, which works best on 1029 This is a rather advanced IO::AIO call, which works best on
805 mmap(2)ed scalars. 1030 mmap(2)ed scalars.
… …
825 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1050 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
826 aio_mlock $data; # mlock in background 1051 aio_mlock $data; # mlock in background
827 1052
828 aio_mlockall $flags, $callback->($status) 1053 aio_mlockall $flags, $callback->($status)
829 Calls the "mlockall" function with the given $flags (a combination 1054 Calls the "mlockall" function with the given $flags (a combination
830 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). 1055 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1056 "IO::AIO::MCL_ONFAULT").
831 1057
832 On systems that do not implement "mlockall", this function returns 1058 On systems that do not implement "mlockall", this function returns
833 -1 and sets errno to "ENOSYS". 1059 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1060 supported by the system result in a return value of -1 with errno
1061 being set to "EINVAL".
834 1062
835 Note that the corresponding "munlockall" is synchronous and is 1063 Note that the corresponding "munlockall" is synchronous and is
836 documented under "MISCELLANEOUS FUNCTIONS". 1064 documented under "MISCELLANEOUS FUNCTIONS".
837 1065
838 Example: asynchronously lock all current and future pages into 1066 Example: asynchronously lock all current and future pages into
839 memory. 1067 memory.
840 1068
841 aio_mlockall IO::AIO::MCL_FUTURE; 1069 aio_mlockall IO::AIO::MCL_FUTURE;
1070
1071 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1072 Queries the extents of the given file (by calling the Linux "FIEMAP"
1073 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1074 details). If the ioctl is not available on your OS, then this
1075 request will fail with "ENOSYS".
1076
1077 $start is the starting offset to query extents for, $length is the
1078 size of the range to query - if it is "undef", then the whole file
1079 will be queried.
1080
1081 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1082 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1083 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1084 query the data portion.
1085
1086 $count is the maximum number of extent records to return. If it is
1087 "undef", then IO::AIO queries all extents of the range. As a very
1088 special case, if it is 0, then the callback receives the number of
1089 extents instead of the extents themselves (which is unreliable, see
1090 below).
1091
1092 If an error occurs, the callback receives no arguments. The special
1093 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1094
1095 Otherwise, the callback receives an array reference with extent
1096 structures. Each extent structure is an array reference itself, with
1097 the following members:
1098
1099 [$logical, $physical, $length, $flags]
1100
1101 Flags is any combination of the following flag values (typically
1102 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1103
1104 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1105 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1106 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1107 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1108 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1109 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1110 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1111 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1112
1113 At the time of this writing (Linux 3.2), this request is unreliable
1114 unless $count is "undef", as the kernel has all sorts of bugs
1115 preventing it to return all extents of a range for files with a
1116 large number of extents. The code (only) works around all these
1117 issues if $count is "undef".
842 1118
843 aio_group $callback->(...) 1119 aio_group $callback->(...)
844 This is a very special aio request: Instead of doing something, it 1120 This is a very special aio request: Instead of doing something, it
845 is a container for other aio requests, which is useful if you want 1121 is a container for other aio requests, which is useful if you want
846 to bundle many requests into a single, composite, request with a 1122 to bundle many requests into a single, composite, request with a
… …
880 While it is theoretically handy to have simple I/O scheduling 1156 While it is theoretically handy to have simple I/O scheduling
881 requests like sleep and file handle readable/writable, the overhead 1157 requests like sleep and file handle readable/writable, the overhead
882 this creates is immense (it blocks a thread for a long time) so do 1158 this creates is immense (it blocks a thread for a long time) so do
883 not use this function except to put your application under 1159 not use this function except to put your application under
884 artificial I/O pressure. 1160 artificial I/O pressure.
1161
1162 IO::AIO::WD - multiple working directories
1163 Your process only has one current working directory, which is used by
1164 all threads. This makes it hard to use relative paths (some other
1165 component could call "chdir" at any time, and it is hard to control when
1166 the path will be used by IO::AIO).
1167
1168 One solution for this is to always use absolute paths. This usually
1169 works, but can be quite slow (the kernel has to walk the whole path on
1170 every access), and can also be a hassle to implement.
1171
1172 Newer POSIX systems have a number of functions (openat, fdopendir,
1173 futimensat and so on) that make it possible to specify working
1174 directories per operation.
1175
1176 For portability, and because the clowns who "designed", or shall I
1177 write, perpetrated this new interface were obviously half-drunk, this
1178 abstraction cannot be perfect, though.
1179
1180 IO::AIO allows you to convert directory paths into a so-called
1181 IO::AIO::WD object. This object stores the canonicalised, absolute
1182 version of the path, and on systems that allow it, also a directory file
1183 descriptor.
1184
1185 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1186 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1187 object and a pathname instead (or the IO::AIO::WD object alone, which
1188 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1189 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1190 relative to that IO::AIO::WD object.
1191
1192 For example, to get a wd object for /etc and then stat passwd inside,
1193 you would write:
1194
1195 aio_wd "/etc", sub {
1196 my $etcdir = shift;
1197
1198 # although $etcdir can be undef on error, there is generally no reason
1199 # to check for errors here, as aio_stat will fail with ENOENT
1200 # when $etcdir is undef.
1201
1202 aio_stat [$etcdir, "passwd"], sub {
1203 # yay
1204 };
1205 };
1206
1207 The fact that "aio_wd" is a request and not a normal function shows that
1208 creating an IO::AIO::WD object is itself a potentially blocking
1209 operation, which is why it is done asynchronously.
1210
1211 To stat the directory obtained with "aio_wd" above, one could write
1212 either of the following three request calls:
1213
1214 aio_lstat "/etc" , sub { ... # pathname as normal string
1215 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1216 aio_lstat $wd , sub { ... # shorthand for the previous
1217
1218 As with normal pathnames, IO::AIO keeps a copy of the working directory
1219 object and the pathname string, so you could write the following without
1220 causing any issues due to $path getting reused:
1221
1222 my $path = [$wd, undef];
1223
1224 for my $name (qw(abc def ghi)) {
1225 $path->[1] = $name;
1226 aio_stat $path, sub {
1227 # ...
1228 };
1229 }
1230
1231 There are some caveats: when directories get renamed (or deleted), the
1232 pathname string doesn't change, so will point to the new directory (or
1233 nowhere at all), while the directory fd, if available on the system,
1234 will still point to the original directory. Most functions accepting a
1235 pathname will use the directory fd on newer systems, and the string on
1236 older systems. Some functions (such as "aio_realpath") will always rely
1237 on the string form of the pathname.
1238
1239 So this functionality is mainly useful to get some protection against
1240 "chdir", to easily get an absolute path out of a relative path for
1241 future reference, and to speed up doing many operations in the same
1242 directory (e.g. when stat'ing all files in a directory).
1243
1244 The following functions implement this working directory abstraction:
1245
1246 aio_wd $pathname, $callback->($wd)
1247 Asynchonously canonicalise the given pathname and convert it to an
1248 IO::AIO::WD object representing it. If possible and supported on the
1249 system, also open a directory fd to speed up pathname resolution
1250 relative to this working directory.
1251
1252 If something goes wrong, then "undef" is passwd to the callback
1253 instead of a working directory object and $! is set appropriately.
1254 Since passing "undef" as working directory component of a pathname
1255 fails the request with "ENOENT", there is often no need for error
1256 checking in the "aio_wd" callback, as future requests using the
1257 value will fail in the expected way.
1258
1259 IO::AIO::CWD
1260 This is a compile time constant (object) that represents the process
1261 current working directory.
1262
1263 Specifying this object as working directory object for a pathname is
1264 as if the pathname would be specified directly, without a directory
1265 object. For example, these calls are functionally identical:
1266
1267 aio_stat "somefile", sub { ... };
1268 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1269
1270 To recover the path associated with an IO::AIO::WD object, you can use
1271 "aio_realpath":
1272
1273 aio_realpath $wd, sub {
1274 warn "path is $_[0]\n";
1275 };
1276
1277 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1278 sometimes, fall back to using an absolue path.
885 1279
886 IO::AIO::REQ CLASS 1280 IO::AIO::REQ CLASS
887 All non-aggregate "aio_*" functions return an object of this class when 1281 All non-aggregate "aio_*" functions return an object of this class when
888 called in non-void context. 1282 called in non-void context.
889 1283
… …
989 Sets a feeder/generator on this group: every group can have an 1383 Sets a feeder/generator on this group: every group can have an
990 attached generator that generates requests if idle. The idea behind 1384 attached generator that generates requests if idle. The idea behind
991 this is that, although you could just queue as many requests as you 1385 this is that, although you could just queue as many requests as you
992 want in a group, this might starve other requests for a potentially 1386 want in a group, this might starve other requests for a potentially
993 long time. For example, "aio_scandir" might generate hundreds of 1387 long time. For example, "aio_scandir" might generate hundreds of
994 thousands "aio_stat" requests, delaying any later requests for a 1388 thousands of "aio_stat" requests, delaying any later requests for a
995 long time. 1389 long time.
996 1390
997 To avoid this, and allow incremental generation of requests, you can 1391 To avoid this, and allow incremental generation of requests, you can
998 instead a group and set a feeder on it that generates those 1392 instead a group and set a feeder on it that generates those
999 requests. The feed callback will be called whenever there are few 1393 requests. The feed callback will be called whenever there are few
… …
1041 results. 1435 results.
1042 1436
1043 See "poll_cb" for an example. 1437 See "poll_cb" for an example.
1044 1438
1045 IO::AIO::poll_cb 1439 IO::AIO::poll_cb
1046 Process some outstanding events on the result pipe. You have to call 1440 Process some requests that have reached the result phase (i.e. they
1441 have been executed but the results are not yet reported). You have
1442 to call this "regularly" to finish outstanding requests.
1443
1047 this regularly. Returns 0 if all events could be processed (or there 1444 Returns 0 if all events could be processed (or there were no events
1048 were no events to process), or -1 if it returned earlier for 1445 to process), or -1 if it returned earlier for whatever reason.
1049 whatever reason. Returns immediately when no events are outstanding. 1446 Returns immediately when no events are outstanding. The amount of
1050 The amount of events processed depends on the settings of 1447 events processed depends on the settings of "IO::AIO::max_poll_req",
1051 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". 1448 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1052 1449
1053 If not all requests were processed for whatever reason, the 1450 If not all requests were processed for whatever reason, the poll
1054 filehandle will still be ready when "poll_cb" returns, so normally 1451 file descriptor will still be ready when "poll_cb" returns, so
1055 you don't have to do anything special to have it called later. 1452 normally you don't have to do anything special to have it called
1453 later.
1056 1454
1057 Apart from calling "IO::AIO::poll_cb" when the event filehandle 1455 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1058 becomes ready, it can be beneficial to call this function from loops 1456 becomes ready, it can be beneficial to call this function from loops
1059 which submit a lot of requests, to make sure the results get 1457 which submit a lot of requests, to make sure the results get
1060 processed when they become available and not just when the loop is 1458 processed when they become available and not just when the loop is
… …
1068 Event->io (fd => IO::AIO::poll_fileno, 1466 Event->io (fd => IO::AIO::poll_fileno,
1069 poll => 'r', async => 1, 1467 poll => 'r', async => 1,
1070 cb => \&IO::AIO::poll_cb); 1468 cb => \&IO::AIO::poll_cb);
1071 1469
1072 IO::AIO::poll_wait 1470 IO::AIO::poll_wait
1073 If there are any outstanding requests and none of them in the result 1471 Wait until either at least one request is in the result phase or no
1074 phase, wait till the result filehandle becomes ready for reading 1472 requests are outstanding anymore.
1075 (simply does a "select" on the filehandle. This is useful if you 1473
1076 want to synchronously wait for some requests to finish). 1474 This is useful if you want to synchronously wait for some requests
1475 to become ready, without actually handling them.
1077 1476
1078 See "nreqs" for an example. 1477 See "nreqs" for an example.
1079 1478
1080 IO::AIO::poll 1479 IO::AIO::poll
1081 Waits until some requests have been handled. 1480 Waits until some requests have been handled.
… …
1090 1489
1091 Strictly equivalent to: 1490 Strictly equivalent to:
1092 1491
1093 IO::AIO::poll_wait, IO::AIO::poll_cb 1492 IO::AIO::poll_wait, IO::AIO::poll_cb
1094 while IO::AIO::nreqs; 1493 while IO::AIO::nreqs;
1494
1495 This function can be useful at program aborts, to make sure
1496 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1497 already calls this function on normal exits), or when you are merely
1498 using "IO::AIO" for its more advanced functions, rather than for
1499 async I/O, e.g.:
1500
1501 my ($dirs, $nondirs);
1502 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1503 IO::AIO::flush;
1504 # $dirs, $nondirs are now set
1095 1505
1096 IO::AIO::max_poll_reqs $nreqs 1506 IO::AIO::max_poll_reqs $nreqs
1097 IO::AIO::max_poll_time $seconds 1507 IO::AIO::max_poll_time $seconds
1098 These set the maximum number of requests (default 0, meaning 1508 These set the maximum number of requests (default 0, meaning
1099 infinity) that are being processed by "IO::AIO::poll_cb" in one 1509 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
1189 no longer exceeded. 1599 no longer exceeded.
1190 1600
1191 In other words, this setting does not enforce a queue limit, but can 1601 In other words, this setting does not enforce a queue limit, but can
1192 be used to make poll functions block if the limit is exceeded. 1602 be used to make poll functions block if the limit is exceeded.
1193 1603
1194 This is a very bad function to use in interactive programs because 1604 This is a bad function to use in interactive programs because it
1195 it blocks, and a bad way to reduce concurrency because it is 1605 blocks, and a bad way to reduce concurrency because it is inexact.
1196 inexact: Better use an "aio_group" together with a feed callback. 1606 If you need to issue many requests without being able to call a poll
1607 function on demand, it is better to use an "aio_group" together with
1608 a feed callback.
1197 1609
1198 It's main use is in scripts without an event loop - when you want to 1610 Its main use is in scripts without an event loop - when you want to
1199 stat a lot of files, you can write somehting like this: 1611 stat a lot of files, you can write something like this:
1200 1612
1201 IO::AIO::max_outstanding 32; 1613 IO::AIO::max_outstanding 32;
1202 1614
1203 for my $path (...) { 1615 for my $path (...) {
1204 aio_stat $path , ...; 1616 aio_stat $path , ...;
… …
1206 } 1618 }
1207 1619
1208 IO::AIO::flush; 1620 IO::AIO::flush;
1209 1621
1210 The call to "poll_cb" inside the loop will normally return 1622 The call to "poll_cb" inside the loop will normally return
1211 instantly, but as soon as more thna 32 reqeusts are in-flight, it 1623 instantly, allowing the loop to progress, but as soon as more than
1212 will block until some requests have been handled. This keeps the 1624 32 requests are in-flight, it will block until some requests have
1213 loop from pushing a large number of "aio_stat" requests onto the 1625 been handled. This keeps the loop from pushing a large number of
1214 queue. 1626 "aio_stat" requests onto the queue (which, with many paths to stat,
1627 can use up a lot of memory).
1215 1628
1216 The default value for "max_outstanding" is very large, so there is 1629 The default value for "max_outstanding" is very large, so there is
1217 no practical limit on the number of outstanding requests. 1630 no practical limit on the number of outstanding requests.
1218 1631
1219 STATISTICAL INFORMATION 1632 STATISTICAL INFORMATION
… …
1233 1646
1234 IO::AIO::npending 1647 IO::AIO::npending
1235 Returns the number of requests currently in the pending state 1648 Returns the number of requests currently in the pending state
1236 (executed, but not yet processed by poll_cb). 1649 (executed, but not yet processed by poll_cb).
1237 1650
1651 SUBSECOND STAT TIME ACCESS
1652 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1653 generally find access/modification and change times with subsecond time
1654 accuracy of the system supports it, but perl's built-in functions only
1655 return the integer part.
1656
1657 The following functions return the timestamps of the most recent stat
1658 with subsecond precision on most systems and work both after
1659 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1660 value is only meaningful after a successful "stat"/"lstat" call, or
1661 during/after a successful "aio_stat"/"aio_lstat" callback.
1662
1663 This is similar to the Time::HiRes "stat" functions, but can return full
1664 resolution without rounding and work with standard perl "stat",
1665 alleviating the need to call the special "Time::HiRes" functions, which
1666 do not act like their perl counterparts.
1667
1668 On operating systems or file systems where subsecond time resolution is
1669 not supported or could not be detected, a fractional part of 0 is
1670 returned, so it is always safe to call these functions.
1671
1672 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1673 IO::AIO::st_btime
1674 Return the access, modication, change or birth time, respectively,
1675 including fractional part. Due to the limited precision of floating
1676 point, the accuracy on most platforms is only a bit better than
1677 milliseconds for times around now - see the *nsec* function family,
1678 below, for full accuracy.
1679
1680 File birth time is only available when the OS and perl support it
1681 (on FreeBSD and NetBSD at the time of this writing, although support
1682 is adaptive, so if your OS/perl gains support, IO::AIO can take
1683 advantage of it). On systems where it isn't available, 0 is
1684 currently returned, but this might change to "undef" in a future
1685 version.
1686
1687 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1688 Returns access, modification, change and birth time all in one go,
1689 and maybe more times in the future version.
1690
1691 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1692 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1693 Return the fractional access, modifcation, change or birth time, in
1694 nanoseconds, as an integer in the range 0 to 999999999.
1695
1696 Note that no accessors are provided for access, modification and
1697 change times - you need to get those from "stat _" if required ("int
1698 IO::AIO::st_atime" and so on will *not* generally give you the
1699 correct value).
1700
1701 $seconds = IO::AIO::st_btimesec
1702 The (integral) seconds part of the file birth time, if available.
1703
1704 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1705 Like the functions above, but returns all four times in one go (and
1706 maybe more in future versions).
1707
1708 $counter = IO::AIO::st_gen
1709 Returns the generation counter (in practice this is just a random
1710 number) of the file. This is only available on platforms which have
1711 this member in their "struct stat" (most BSDs at the time of this
1712 writing) and generally only to the root usert. If unsupported, 0 is
1713 returned, but this might change to "undef" in a future version.
1714
1715 Example: print the high resolution modification time of /etc, using
1716 "stat", and "IO::AIO::aio_stat".
1717
1718 if (stat "/etc") {
1719 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1720 }
1721
1722 IO::AIO::aio_stat "/etc", sub {
1723 $_[0]
1724 and return;
1725
1726 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1727 };
1728
1729 IO::AIO::flush;
1730
1731 Output of the awbove on my system, showing reduced and full accuracy:
1732
1733 stat(/etc) mtime: 1534043702.020808
1734 aio_stat(/etc) mtime: 1534043702.020807792
1735
1238 MISCELLANEOUS FUNCTIONS 1736 MISCELLANEOUS FUNCTIONS
1239 IO::AIO implements some functions that might be useful, but are not 1737 IO::AIO implements some functions that are useful when you want to use
1240 asynchronous. 1738 some "Advanced I/O" function not available to in Perl, without going the
1739 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1740 counterpart.
1741
1742 $retval = IO::AIO::fexecve $fh, $argv, $envp
1743 A more-or-less direct equivalent to the POSIX "fexecve" functions,
1744 which allows you to specify the program to be executed via a file
1745 descriptor (or handle). Returns -1 and sets errno to "ENOSYS" if not
1746 available.
1747
1748 $numfd = IO::AIO::get_fdlimit
1749 Tries to find the current file descriptor limit and returns it, or
1750 "undef" and sets $! in case of an error. The limit is one larger
1751 than the highest valid file descriptor number.
1752
1753 IO::AIO::min_fdlimit [$numfd]
1754 Try to increase the current file descriptor limit(s) to at least
1755 $numfd by changing the soft or hard file descriptor resource limit.
1756 If $numfd is missing, it will try to set a very high limit, although
1757 this is not recommended when you know the actual minimum that you
1758 require.
1759
1760 If the limit cannot be raised enough, the function makes a
1761 best-effort attempt to increase the limit as much as possible, using
1762 various tricks, while still failing. You can query the resulting
1763 limit using "IO::AIO::get_fdlimit".
1764
1765 If an error occurs, returns "undef" and sets $!, otherwise returns
1766 true.
1241 1767
1242 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1768 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1243 Calls the "eio_sendfile_sync" function, which is like 1769 Calls the "eio_sendfile_sync" function, which is like
1244 "aio_sendfile", but is blocking (this makes most sense if you know 1770 "aio_sendfile", but is blocking (this makes most sense if you know
1245 the input data is likely cached already and the output filehandle is 1771 the input data is likely cached already and the output filehandle is
… …
1247 1773
1248 Returns the number of bytes copied, or -1 on error. 1774 Returns the number of bytes copied, or -1 on error.
1249 1775
1250 IO::AIO::fadvise $fh, $offset, $len, $advice 1776 IO::AIO::fadvise $fh, $offset, $len, $advice
1251 Simply calls the "posix_fadvise" function (see its manpage for 1777 Simply calls the "posix_fadvise" function (see its manpage for
1252 details). The following advice constants are avaiable: 1778 details). The following advice constants are available:
1253 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1779 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1254 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1780 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1255 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1781 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1256 1782
1257 On systems that do not implement "posix_fadvise", this function 1783 On systems that do not implement "posix_fadvise", this function
1258 returns ENOSYS, otherwise the return value of "posix_fadvise". 1784 returns ENOSYS, otherwise the return value of "posix_fadvise".
1259 1785
1260 IO::AIO::madvise $scalar, $offset, $len, $advice 1786 IO::AIO::madvise $scalar, $offset, $len, $advice
1261 Simply calls the "posix_madvise" function (see its manpage for 1787 Simply calls the "posix_madvise" function (see its manpage for
1262 details). The following advice constants are avaiable: 1788 details). The following advice constants are available:
1263 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", 1789 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1264 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", 1790 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1265 "IO::AIO::MADV_DONTNEED". 1791 "IO::AIO::MADV_DONTNEED".
1266 1792
1793 If $offset is negative, counts from the end. If $length is negative,
1794 the remaining length of the $scalar is used. If possible, $length
1795 will be reduced to fit into the $scalar.
1796
1267 On systems that do not implement "posix_madvise", this function 1797 On systems that do not implement "posix_madvise", this function
1268 returns ENOSYS, otherwise the return value of "posix_madvise". 1798 returns ENOSYS, otherwise the return value of "posix_madvise".
1269 1799
1270 IO::AIO::mprotect $scalar, $offset, $len, $protect 1800 IO::AIO::mprotect $scalar, $offset, $len, $protect
1271 Simply calls the "mprotect" function on the preferably AIO::mmap'ed 1801 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1272 $scalar (see its manpage for details). The following protect 1802 $scalar (see its manpage for details). The following protect
1273 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", 1803 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1274 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". 1804 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1805
1806 If $offset is negative, counts from the end. If $length is negative,
1807 the remaining length of the $scalar is used. If possible, $length
1808 will be reduced to fit into the $scalar.
1275 1809
1276 On systems that do not implement "mprotect", this function returns 1810 On systems that do not implement "mprotect", this function returns
1277 ENOSYS, otherwise the return value of "mprotect". 1811 ENOSYS, otherwise the return value of "mprotect".
1278 1812
1279 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1813 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1280 Memory-maps a file (or anonymous memory range) and attaches it to 1814 Memory-maps a file (or anonymous memory range) and attaches it to
1281 the given $scalar, which will act like a string scalar. 1815 the given $scalar, which will act like a string scalar. Returns true
1816 on success, and false otherwise.
1282 1817
1818 The scalar must exist, but its contents do not matter - this means
1819 you cannot use a nonexistant array or hash element. When in doubt,
1820 "undef" the scalar first.
1821
1283 The only operations allowed on the scalar are "substr"/"vec" that 1822 The only operations allowed on the mmapped scalar are
1284 don't change the string length, and most read-only operations such 1823 "substr"/"vec", which don't change the string length, and most
1285 as copying it or searching it with regexes and so on. 1824 read-only operations such as copying it or searching it with regexes
1825 and so on.
1286 1826
1287 Anything else is unsafe and will, at best, result in memory leaks. 1827 Anything else is unsafe and will, at best, result in memory leaks.
1288 1828
1289 The memory map associated with the $scalar is automatically removed 1829 The memory map associated with the $scalar is automatically removed
1290 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1830 when the $scalar is undef'd or destroyed, or when the
1291 "IO::AIO::munmap" functions are called. 1831 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1292 1832
1293 This calls the "mmap"(2) function internally. See your system's 1833 This calls the "mmap"(2) function internally. See your system's
1294 manual page for details on the $length, $prot and $flags parameters. 1834 manual page for details on the $length, $prot and $flags parameters.
1295 1835
1296 The $length must be larger than zero and smaller than the actual 1836 The $length must be larger than zero and smaller than the actual
… …
1300 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1840 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1301 "IO::AIO::PROT_WRITE", 1841 "IO::AIO::PROT_WRITE",
1302 1842
1303 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1843 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1304 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1844 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1305 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1845 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1306 (which is set to "MAP_ANON" if your system only provides this 1846 "MAP_ANON" if your system only provides this constant),
1847 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1307 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1848 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1308 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1849 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1309 "IO::AIO::MAP_NONBLOCK" 1850 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
1851 "IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
1852 "IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1310 1853
1311 If $fh is "undef", then a file descriptor of -1 is passed. 1854 If $fh is "undef", then a file descriptor of -1 is passed.
1312 1855
1313 $offset is the offset from the start of the file - it generally must 1856 $offset is the offset from the start of the file - it generally must
1314 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1857 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1326 1869
1327 my $fast_md5 = md5 $data; 1870 my $fast_md5 = md5 $data;
1328 1871
1329 IO::AIO::munmap $scalar 1872 IO::AIO::munmap $scalar
1330 Removes a previous mmap and undefines the $scalar. 1873 Removes a previous mmap and undefines the $scalar.
1874
1875 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1876 $new_address = 0]
1877 Calls the Linux-specific mremap(2) system call. The $scalar must
1878 have been mapped by "IO::AIO::mmap", and $flags must currently
1879 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1880
1881 Returns true if successful, and false otherwise. If the underlying
1882 mmapped region has changed address, then the true value has the
1883 numerical value 1, otherwise it has the numerical value 0:
1884
1885 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1886 or die "mremap: $!";
1887
1888 if ($success*1) {
1889 warn "scalar has chanegd address in memory\n";
1890 }
1891
1892 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1893 implemented, but not supported and might go away in a future
1894 version.
1895
1896 On systems where this call is not supported or is not emulated, this
1897 call returns falls and sets $! to "ENOSYS".
1898
1899 IO::AIO::mlockall $flags
1900 Calls the "eio_mlockall_sync" function, which is like
1901 "aio_mlockall", but is blocking.
1331 1902
1332 IO::AIO::munlock $scalar, $offset = 0, $length = undef 1903 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1333 Calls the "munlock" function, undoing the effects of a previous 1904 Calls the "munlock" function, undoing the effects of a previous
1334 "aio_mlock" call (see its description for details). 1905 "aio_mlock" call (see its description for details).
1335 1906
1336 IO::AIO::munlockall 1907 IO::AIO::munlockall
1337 Calls the "munlockall" function. 1908 Calls the "munlockall" function.
1338 1909
1339 On systems that do not implement "munlockall", this function returns 1910 On systems that do not implement "munlockall", this function returns
1340 ENOSYS, otherwise the return value of "munlockall". 1911 ENOSYS, otherwise the return value of "munlockall".
1912
1913 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1914 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1915 socket and return the new file handle on success, or sets $! and
1916 returns "undef" on error.
1917
1918 The remote name of the new socket will be stored in $sockaddr, which
1919 will be extended to allow for at least $sockaddr_maxlen octets. If
1920 the socket name does not fit into $sockaddr_maxlen octets, this is
1921 signaled by returning a longer string in $sockaddr, which might or
1922 might not be truncated.
1923
1924 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1925 $sockaddr_maxlen.
1926
1927 The main reasons to use this syscall rather than portable accept(2)
1928 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1929 and you can accept name-less sockets by specifying 0 for
1930 $sockaddr_maxlen, which is sadly not possible with perl's interface
1931 to "accept".
1932
1933 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1934 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1935 $w_off are "undef", then "NULL" is passed for these, otherwise they
1936 should be the file offset.
1937
1938 $r_fh and $w_fh should not refer to the same file, as splice might
1939 silently corrupt the data in this case.
1940
1941 The following symbol flag values are available:
1942 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1943 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1944
1945 See the splice(2) manpage for details.
1946
1947 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1948 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1949 description for "IO::AIO::splice" above for details.
1950
1951 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1952 Attempts to query or change the pipe buffer size. Obviously works
1953 only on pipes, and currently works only on GNU/Linux systems, and
1954 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1955 influence pipe buffer size on other systems, drop me a note.
1956
1957 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1958 This is a direct interface to the Linux pipe2(2) system call. If
1959 $flags is missing or 0, then this should be the same as a call to
1960 perl's built-in "pipe" function and create a new pipe, and works on
1961 systems that lack the pipe2 syscall. On win32, this case invokes
1962 "_pipe (..., 4096, O_BINARY)".
1963
1964 If $flags is non-zero, it tries to invoke the pipe2 system call with
1965 the given flags (Linux 2.6.27, glibc 2.9).
1966
1967 On success, the read and write file handles are returned.
1968
1969 On error, nothing will be returned. If the pipe2 syscall is missing
1970 and $flags is non-zero, fails with "ENOSYS".
1971
1972 Please refer to pipe2(2) for more info on the $flags, but at the
1973 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1974 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1975 supported.
1976
1977 Example: create a pipe race-free w.r.t. threads and fork:
1978
1979 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1980 or die "pipe2: $!\n";
1981
1982 $fh = IO::AIO::memfd_create $pathname[, $flags]
1983 This is a direct interface to the Linux memfd_create(2) system call.
1984 The (unhelpful) default for $flags is 0, but your default should be
1985 "IO::AIO::MFD_CLOEXEC".
1986
1987 On success, the new memfd filehandle is returned, otherwise returns
1988 "undef". If the memfd_create syscall is missing, fails with
1989 "ENOSYS".
1990
1991 Please refer to memfd_create(2) for more info on this call.
1992
1993 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1994 "IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
1995 "IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
1996
1997 Example: create a new memfd.
1998
1999 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
2000 or die "memfd_create: $!\n";
2001
2002 $fh = IO::AIO::pidfd_open $pid[, $flags]
2003 This is an interface to the Linux pidfd_open(2) system call. The
2004 default for $flags is 0.
2005
2006 On success, a new pidfd filehandle is returned (that is already set
2007 to close-on-exec), otherwise returns "undef". If the syscall is
2008 missing, fails with "ENOSYS".
2009
2010 Example: open pid 6341 as pidfd.
2011
2012 my $fh = IO::AIO::pidfd_open 6341
2013 or die "pidfd_open: $!\n";
2014
2015 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
2016 $flags]]
2017 This is an interface to the Linux pidfd_send_signal system call. The
2018 default for $siginfo is "undef" and the default for $flags is 0.
2019
2020 Returns the system call status. If the syscall is missing, fails
2021 with "ENOSYS".
2022
2023 When specified, $siginfo must be a reference to a hash with one or
2024 more of the following members:
2025
2026 code - the "si_code" member
2027 pid - the "si_pid" member
2028 uid - the "si_uid" member
2029 value_int - the "si_value.sival_int" member
2030 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2031
2032 Example: send a SIGKILL to the specified process.
2033
2034 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2035 and die "pidfd_send_signal: $!\n";
2036
2037 Example: send a SIGKILL to the specified process with extra data.
2038
2039 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2040 and die "pidfd_send_signal: $!\n";
2041
2042 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2043 This is an interface to the Linux pidfd_getfd system call. The
2044 default for $flags is 0.
2045
2046 On success, returns a dup'ed copy of the target file descriptor
2047 (specified as an integer) returned (that is already set to
2048 close-on-exec), otherwise returns "undef". If the syscall is
2049 missing, fails with "ENOSYS".
2050
2051 Example: get a copy of standard error of another process and print
2052 soemthing to it.
2053
2054 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2055 or die "pidfd_getfd: $!\n";
2056 print $errfh "stderr\n";
2057
2058 $fh = IO::AIO::eventfd [$initval, [$flags]]
2059 This is a direct interface to the Linux eventfd(2) system call. The
2060 (unhelpful) defaults for $initval and $flags are 0 for both.
2061
2062 On success, the new eventfd filehandle is returned, otherwise
2063 returns "undef". If the eventfd syscall is missing, fails with
2064 "ENOSYS".
2065
2066 Please refer to eventfd(2) for more info on this call.
2067
2068 The following symbol flag values are available:
2069 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2070 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2071
2072 Example: create a new eventfd filehandle:
2073
2074 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2075 or die "eventfd: $!\n";
2076
2077 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2078 This is a direct interface to the Linux timerfd_create(2) system
2079 call. The (unhelpful) default for $flags is 0, but your default
2080 should be "IO::AIO::TFD_CLOEXEC".
2081
2082 On success, the new timerfd filehandle is returned, otherwise
2083 returns "undef". If the timerfd_create syscall is missing, fails
2084 with "ENOSYS".
2085
2086 Please refer to timerfd_create(2) for more info on this call.
2087
2088 The following $clockid values are available:
2089 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2090 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2091 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2092 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2093
2094 The following $flags values are available (Linux 2.6.27):
2095 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2096
2097 Example: create a new timerfd and set it to one-second repeated
2098 alarms, then wait for two alarms:
2099
2100 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2101 or die "timerfd_create: $!\n";
2102
2103 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2104 or die "timerfd_settime: $!\n";
2105
2106 for (1..2) {
2107 8 == sysread $fh, my $buf, 8
2108 or die "timerfd read failure\n";
2109
2110 printf "number of expirations (likely 1): %d\n",
2111 unpack "Q", $buf;
2112 }
2113
2114 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2115 $new_interval, $nbw_value
2116 This is a direct interface to the Linux timerfd_settime(2) system
2117 call. Please refer to its manpage for more info on this call.
2118
2119 The new itimerspec is specified using two (possibly fractional)
2120 second values, $new_interval and $new_value).
2121
2122 On success, the current interval and value are returned (as per
2123 "timerfd_gettime"). On failure, the empty list is returned.
2124
2125 The following $flags values are available:
2126 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2127
2128 See "IO::AIO::timerfd_create" for a full example.
2129
2130 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2131 This is a direct interface to the Linux timerfd_gettime(2) system
2132 call. Please refer to its manpage for more info on this call.
2133
2134 On success, returns the current values of interval and value for the
2135 given timerfd (as potentially fractional second values). On failure,
2136 the empty list is returned.
1341 2137
1342EVENT LOOP INTEGRATION 2138EVENT LOOP INTEGRATION
1343 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2139 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1344 automatically into many event loops: 2140 automatically into many event loops:
1345 2141
… …
1371 2167
1372 FORK BEHAVIOUR 2168 FORK BEHAVIOUR
1373 Usage of pthreads in a program changes the semantics of fork 2169 Usage of pthreads in a program changes the semantics of fork
1374 considerably. Specifically, only async-safe functions can be called 2170 considerably. Specifically, only async-safe functions can be called
1375 after fork. Perl doesn't know about this, so in general, you cannot call 2171 after fork. Perl doesn't know about this, so in general, you cannot call
1376 fork with defined behaviour in perl. IO::AIO uses pthreads, so this 2172 fork with defined behaviour in perl if pthreads are involved. IO::AIO
1377 applies, but many other extensions and (for inexplicable reasons) perl 2173 uses pthreads, so this applies, but many other extensions and (for
1378 itself often is linked against pthreads, so this limitation applies. 2174 inexplicable reasons) perl itself often is linked against pthreads, so
2175 this limitation applies to quite a lot of perls.
1379 2176
1380 Some operating systems have extensions that allow safe use of fork, and 2177 This module no longer tries to fight your OS, or POSIX. That means
1381 this module should do "the right thing" on those, and tries on others. 2178 IO::AIO only works in the process that loaded it. Forking is fully
1382 At the time of this writing (2011) only GNU/Linux supports these 2179 supported, but using IO::AIO in the child is not.
1383 extensions to POSIX. 2180
2181 You might get around by not *using* IO::AIO before (or after) forking.
2182 You could also try to call the IO::AIO::reinit function in the child:
2183
2184 IO::AIO::reinit
2185 Abandons all current requests and I/O threads and simply
2186 reinitialises all data structures. This is not an operation
2187 supported by any standards, but happens to work on GNU/Linux and
2188 some newer BSD systems.
2189
2190 The only reasonable use for this function is to call it after
2191 forking, if "IO::AIO" was used in the parent. Calling it while
2192 IO::AIO is active in the process will result in undefined behaviour.
2193 Calling it at any time will also result in any undefined (by POSIX)
2194 behaviour.
2195
2196 LINUX-SPECIFIC CALLS
2197 When a call is documented as "linux-specific" then this means it
2198 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2199 availability and compatibility of such calls regardless of the platform
2200 it is compiled on, so platforms such as FreeBSD which often implement
2201 these calls will work. When in doubt, call them and see if they fail wth
2202 "ENOSYS".
1384 2203
1385 MEMORY USAGE 2204 MEMORY USAGE
1386 Per-request usage: 2205 Per-request usage:
1387 2206
1388 Each aio request uses - depending on your architecture - around 100-200 2207 Each aio request uses - depending on your architecture - around 100-200
… …
1399 In the execution phase, some aio requests require more memory for 2218 In the execution phase, some aio requests require more memory for
1400 temporary buffers, and each thread requires a stack and other data 2219 temporary buffers, and each thread requires a stack and other data
1401 structures (usually around 16k-128k, depending on the OS). 2220 structures (usually around 16k-128k, depending on the OS).
1402 2221
1403KNOWN BUGS 2222KNOWN BUGS
1404 Known bugs will be fixed in the next release. 2223 Known bugs will be fixed in the next release :)
2224
2225KNOWN ISSUES
2226 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2227 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2228 non-created hash slots or other scalars I didn't think of. It's best to
2229 avoid such and either use scalar variables or making sure that the
2230 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2231
2232 I am not sure anything can be done about this, so this is considered a
2233 known issue, rather than a bug.
1405 2234
1406SEE ALSO 2235SEE ALSO
1407 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2236 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1408 more natural syntax. 2237 more natural syntax and IO::FDPass for file descriptor passing.
1409 2238
1410AUTHOR 2239AUTHOR
1411 Marc Lehmann <schmorp@schmorp.de> 2240 Marc Lehmann <schmorp@schmorp.de>
1412 http://home.schmorp.de/ 2241 http://home.schmorp.de/
1413 2242

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