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Revision 1.65 by root, Fri Dec 4 01:19:58 2020 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", O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8 my $fh = shift 8 my $fh = shift
9 or die "/etc/passwd: $!"; 9 or die "/etc/passwd: $!";
10 ... 10 ...
11 }; 11 };
12 12
… …
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;
75 78
76 # queue the request to open /etc/passwd 79 # queue the request to open /etc/passwd
77 aio_open "/etc/passwd", O_RDONLY, 0, sub { 80 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
78 my $fh = shift 81 my $fh = shift
79 or die "error while opening: $!"; 82 or die "error while opening: $!";
80 83
81 # stat'ing filehandles is generally non-blocking 84 # stat'ing filehandles is generally non-blocking
82 my $size = -s $fh; 85 my $size = -s $fh;
… …
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)
204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
205 aio_mlockall $flags, $callback->($status)
192 aio_group $callback->(...) 206 aio_group $callback->(...)
193 aio_nop $callback->() 207 aio_nop $callback->()
194 208
195 $prev_pri = aioreq_pri [$pri] 209 $prev_pri = aioreq_pri [$pri]
196 aioreq_nice $pri_adjust 210 aioreq_nice $pri_adjust
… …
202 IO::AIO::max_poll_reqs $nreqs 216 IO::AIO::max_poll_reqs $nreqs
203 IO::AIO::max_poll_time $seconds 217 IO::AIO::max_poll_time $seconds
204 IO::AIO::min_parallel $nthreads 218 IO::AIO::min_parallel $nthreads
205 IO::AIO::max_parallel $nthreads 219 IO::AIO::max_parallel $nthreads
206 IO::AIO::max_idle $nthreads 220 IO::AIO::max_idle $nthreads
221 IO::AIO::idle_timeout $seconds
207 IO::AIO::max_outstanding $maxreqs 222 IO::AIO::max_outstanding $maxreqs
208 IO::AIO::nreqs 223 IO::AIO::nreqs
209 IO::AIO::nready 224 IO::AIO::nready
210 IO::AIO::npending 225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
211 230
212 IO::AIO::sendfile $ofh, $ifh, $offset, $count 231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
213 IO::AIO::fadvise $fh, $offset, $len, $advice 232 IO::AIO::fadvise $fh, $offset, $len, $advice
214 IO::AIO::mlockall $flags 233
234 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
235 IO::AIO::munmap $scalar
236 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
237 IO::AIO::madvise $scalar, $offset, $length, $advice
238 IO::AIO::mprotect $scalar, $offset, $length, $protect
239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
215 IO::AIO::munlockall 240 IO::AIO::munlockall
216 241
217 AIO REQUEST FUNCTIONS 242 # stat extensions
243 $counter = IO::AIO::st_gen
244 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
245 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
246 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
247 $seconds = IO::AIO::st_btimesec
248 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
249
250 # very much unportable syscalls
251 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
252 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
253 IO::AIO::tee $r_fh, $w_fh, $length, $flags
254 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
255 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
256 $fh = IO::AIO::memfd_create $pathname[, $flags]
257 $fh = IO::AIO::eventfd [$initval, [$flags]]
258 $fh = IO::AIO::timerfd_create $clockid[, $flags]
259 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
260 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
261
262 API NOTES
218 All the "aio_*" calls are more or less thin wrappers around the syscall 263 All the "aio_*" calls are more or less thin wrappers around the syscall
219 with the same name (sans "aio_"). The arguments are similar or 264 with the same name (sans "aio_"). The arguments are similar or
220 identical, and they all accept an additional (and optional) $callback 265 identical, and they all accept an additional (and optional) $callback
221 argument which must be a code reference. This code reference will get 266 argument which must be a code reference. This code reference will be
222 called with the syscall return code (e.g. most syscalls return -1 on
223 error, unlike perl, which usually delivers "false") as its sole argument
224 after the given syscall has been executed asynchronously. 267 called after the syscall has been executed in an asynchronous fashion.
268 The results of the request will be passed as arguments to the callback
269 (and, if an error occured, in $!) - for most requests the syscall return
270 code (e.g. most syscalls return -1 on error, unlike perl, which usually
271 delivers "false").
272
273 Some requests (such as "aio_readdir") pass the actual results and
274 communicate failures by passing "undef".
225 275
226 All functions expecting a filehandle keep a copy of the filehandle 276 All functions expecting a filehandle keep a copy of the filehandle
227 internally until the request has finished. 277 internally until the request has finished.
228 278
229 All functions return request objects of type IO::AIO::REQ that allow 279 All functions return request objects of type IO::AIO::REQ that allow
230 further manipulation of those requests while they are in-flight. 280 further manipulation of those requests while they are in-flight.
231 281
232 The pathnames you pass to these routines *must* be absolute and encoded 282 The pathnames you pass to these routines *should* be absolute. The
233 as octets. The reason for the former is that at the time the request is 283 reason for this is that at the time the request is being executed, the
234 being executed, the current working directory could have changed. 284 current working directory could have changed. Alternatively, you can
235 Alternatively, you can make sure that you never change the current 285 make sure that you never change the current working directory anywhere
236 working directory anywhere in the program and then use relative paths. 286 in the program and then use relative paths. You can also take advantage
287 of IO::AIOs working directory abstraction, that lets you specify paths
288 relative to some previously-opened "working directory object" - see the
289 description of the "IO::AIO::WD" class later in this document.
237 290
238 To encode pathnames as octets, either make sure you either: a) always 291 To encode pathnames as octets, either make sure you either: a) always
239 pass in filenames you got from outside (command line, readdir etc.) 292 pass in filenames you got from outside (command line, readdir etc.)
240 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 293 without tinkering, b) are in your native filesystem encoding, c) use the
241 and encode your pathnames to the locale (or other) encoding in effect in 294 Encode module and encode your pathnames to the locale (or other)
242 the user environment, d) use Glib::filename_from_unicode on unicode 295 encoding in effect in the user environment, d) use
243 filenames or e) use something else to ensure your scalar has the correct 296 Glib::filename_from_unicode on unicode filenames or e) use something
244 contents. 297 else to ensure your scalar has the correct contents.
245 298
246 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 299 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
247 handles correctly whether it is set or not. 300 handles correctly whether it is set or not.
248 301
302 AIO REQUEST FUNCTIONS
249 $prev_pri = aioreq_pri [$pri] 303 $prev_pri = aioreq_pri [$pri]
250 Returns the priority value that would be used for the next request 304 Returns the priority value that would be used for the next request
251 and, if $pri is given, sets the priority for the next aio request. 305 and, if $pri is given, sets the priority for the next aio request.
252 306
253 The default priority is 0, the minimum and maximum priorities are -4 307 The default priority is 0, the minimum and maximum priorities are -4
… …
275 Similar to "aioreq_pri", but subtracts the given value from the 329 Similar to "aioreq_pri", but subtracts the given value from the
276 current priority, so the effect is cumulative. 330 current priority, so the effect is cumulative.
277 331
278 aio_open $pathname, $flags, $mode, $callback->($fh) 332 aio_open $pathname, $flags, $mode, $callback->($fh)
279 Asynchronously open or create a file and call the callback with a 333 Asynchronously open or create a file and call the callback with a
280 newly created filehandle for the file. 334 newly created filehandle for the file (or "undef" in case of an
335 error).
281 336
282 The pathname passed to "aio_open" must be absolute. See API NOTES, 337 The pathname passed to "aio_open" must be absolute. See API NOTES,
283 above, for an explanation. 338 above, for an explanation.
284 339
285 The $flags argument is a bitmask. See the "Fcntl" module for a list. 340 The $flags argument is a bitmask. See the "Fcntl" module for a list.
… …
292 will be modified by the umask in effect then the request is being 347 will be modified by the umask in effect then the request is being
293 executed, so better never change the umask. 348 executed, so better never change the umask.
294 349
295 Example: 350 Example:
296 351
297 aio_open "/etc/passwd", O_RDONLY, 0, sub { 352 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
298 if ($_[0]) { 353 if ($_[0]) {
299 print "open successful, fh is $_[0]\n"; 354 print "open successful, fh is $_[0]\n";
300 ... 355 ...
301 } else { 356 } else {
302 die "open failed: $!\n"; 357 die "open failed: $!\n";
303 } 358 }
304 }; 359 };
305 360
361 In addition to all the common open modes/flags ("O_RDONLY",
362 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
363 "O_APPEND"), the following POSIX and non-POSIX constants are
364 available (missing ones on your system are, as usual, 0):
365
366 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
367 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
368 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
369 and "O_ACCMODE".
370
306 aio_close $fh, $callback->($status) 371 aio_close $fh, $callback->($status)
307 Asynchronously close a file and call the callback with the result 372 Asynchronously close a file and call the callback with the result
308 code. 373 code.
309 374
310 Unfortunately, you can't do this to perl. Perl *insists* very 375 Unfortunately, you can't do this to perl. Perl *insists* very
… …
315 will use dup2 to overwrite the file descriptor with the write-end of 380 will use dup2 to overwrite the file descriptor with the write-end of
316 a pipe (the pipe fd will be created on demand and will be cached). 381 a pipe (the pipe fd will be created on demand and will be cached).
317 382
318 Or in other words: the file descriptor will be closed, but it will 383 Or in other words: the file descriptor will be closed, but it will
319 not be free for reuse until the perl filehandle is closed. 384 not be free for reuse until the perl filehandle is closed.
385
386 aio_seek $fh, $offset, $whence, $callback->($offs)
387 Seeks the filehandle to the new $offset, similarly to perl's
388 "sysseek". The $whence can use the traditional values (0 for
389 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
390 "IO::AIO::SEEK_END").
391
392 The resulting absolute offset will be passed to the callback, or -1
393 in case of an error.
394
395 In theory, the $whence constants could be different than the
396 corresponding values from Fcntl, but perl guarantees they are the
397 same, so don't panic.
398
399 As a GNU/Linux (and maybe Solaris) extension, also the constants
400 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
401 could be found. No guarantees about suitability for use in
402 "aio_seek" or Perl's "sysseek" can be made though, although I would
403 naively assume they "just work".
320 404
321 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 406 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
323 Reads or writes $length bytes from or to the specified $fh and 407 Reads or writes $length bytes from or to the specified $fh and
324 $offset into the scalar given by $data and offset $dataoffset and 408 $offset into the scalar given by $data and offset $dataoffset and
325 calls the callback without the actual number of bytes read (or -1 on 409 calls the callback with the actual number of bytes transferred (or
326 error, just like the syscall). 410 -1 on error, just like the syscall).
327 411
328 "aio_read" will, like "sysread", shrink or grow the $data scalar to 412 "aio_read" will, like "sysread", shrink or grow the $data scalar to
329 offset plus the actual number of bytes read. 413 offset plus the actual number of bytes read.
330 414
331 If $offset is undefined, then the current file descriptor offset 415 If $offset is undefined, then the current file descriptor offset
… …
353 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 437 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
354 Tries to copy $length bytes from $in_fh to $out_fh. It starts 438 Tries to copy $length bytes from $in_fh to $out_fh. It starts
355 reading at byte offset $in_offset, and starts writing at the current 439 reading at byte offset $in_offset, and starts writing at the current
356 file offset of $out_fh. Because of that, it is not safe to issue 440 file offset of $out_fh. Because of that, it is not safe to issue
357 more than one "aio_sendfile" per $out_fh, as they will interfere 441 more than one "aio_sendfile" per $out_fh, as they will interfere
358 with each other. 442 with each other. The same $in_fh works fine though, as this function
443 does not move or use the file offset of $in_fh.
359 444
445 Please note that "aio_sendfile" can read more bytes from $in_fh than
446 are written, and there is no way to find out how many more bytes
447 have been read from "aio_sendfile" alone, as "aio_sendfile" only
448 provides the number of bytes written to $out_fh. Only if the result
449 value equals $length one can assume that $length bytes have been
450 read.
451
452 Unlike with other "aio_" functions, it makes a lot of sense to use
453 "aio_sendfile" on non-blocking sockets, as long as one end
454 (typically the $in_fh) is a file - the file I/O will then be
455 asynchronous, while the socket I/O will be non-blocking. Note,
456 however, that you can run into a trap where "aio_sendfile" reads
457 some data with readahead, then fails to write all data, and when the
458 socket is ready the next time, the data in the cache is already
459 lost, forcing "aio_sendfile" to again hit the disk. Explicit
460 "aio_read" + "aio_write" let's you better control resource usage.
461
360 This call tries to make use of a native "sendfile" syscall to 462 This call tries to make use of a native "sendfile"-like syscall to
361 provide zero-copy operation. For this to work, $out_fh should refer 463 provide zero-copy operation. For this to work, $out_fh should refer
362 to a socket, and $in_fh should refer to an mmap'able file. 464 to a socket, and $in_fh should refer to an mmap'able file.
363 465
364 If a native sendfile cannot be found or it fails with "ENOSYS", 466 If a native sendfile cannot be found or it fails with "ENOSYS",
365 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", 467 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
366 it will be emulated, so you can call "aio_sendfile" on any type of 468 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
367 filehandle regardless of the limitations of the operating system. 469 any type of filehandle regardless of the limitations of the
470 operating system.
368 471
369 Please note, however, that "aio_sendfile" can read more bytes from 472 As native sendfile syscalls (as practically any non-POSIX interface
370 $in_fh than are written, and there is no way to find out how many 473 hacked together in a hurry to improve benchmark numbers) tend to be
371 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 474 rather buggy on many systems, this implementation tries to work
372 only provides the number of bytes written to $out_fh. Only if the 475 around some known bugs in Linux and FreeBSD kernels (probably
373 result value equals $length one can assume that $length bytes have 476 others, too), but that might fail, so you really really should check
374 been read. 477 the return value of "aio_sendfile" - fewer bytes than expected might
478 have been transferred.
375 479
376 aio_readahead $fh,$offset,$length, $callback->($retval) 480 aio_readahead $fh,$offset,$length, $callback->($retval)
377 "aio_readahead" populates the page cache with data from a file so 481 "aio_readahead" populates the page cache with data from a file so
378 that subsequent reads from that file will not block on disk I/O. The 482 that subsequent reads from that file will not block on disk I/O. The
379 $offset argument specifies the starting point from which data is to 483 $offset argument specifies the starting point from which data is to
… …
382 to a page boundary and bytes are read up to the next page boundary 486 to a page boundary and bytes are read up to the next page boundary
383 greater than or equal to (off-set+length). "aio_readahead" does not 487 greater than or equal to (off-set+length). "aio_readahead" does not
384 read beyond the end of the file. The current file offset of the file 488 read beyond the end of the file. The current file offset of the file
385 is left unchanged. 489 is left unchanged.
386 490
387 If that syscall doesn't exist (likely if your OS isn't Linux) it 491 If that syscall doesn't exist (likely if your kernel isn't Linux) it
388 will be emulated by simply reading the data, which would have a 492 will be emulated by simply reading the data, which would have a
389 similar effect. 493 similar effect.
390 494
391 aio_stat $fh_or_path, $callback->($status) 495 aio_stat $fh_or_path, $callback->($status)
392 aio_lstat $fh, $callback->($status) 496 aio_lstat $fh, $callback->($status)
393 Works like perl's "stat" or "lstat" in void context. The callback 497 Works almost exactly like perl's "stat" or "lstat" in void context.
394 will be called after the stat and the results will be available 498 The callback will be called after the stat and the results will be
395 using "stat _" or "-s _" etc... 499 available using "stat _" or "-s _" and other tests (with the
500 exception of "-B" and "-T").
396 501
397 The pathname passed to "aio_stat" must be absolute. See API NOTES, 502 The pathname passed to "aio_stat" must be absolute. See API NOTES,
398 above, for an explanation. 503 above, for an explanation.
399 504
400 Currently, the stats are always 64-bit-stats, i.e. instead of 505 Currently, the stats are always 64-bit-stats, i.e. instead of
401 returning an error when stat'ing a large file, the results will be 506 returning an error when stat'ing a large file, the results will be
402 silently truncated unless perl itself is compiled with large file 507 silently truncated unless perl itself is compiled with large file
403 support. 508 support.
509
510 To help interpret the mode and dev/rdev stat values, IO::AIO offers
511 the following constants and functions (if not implemented, the
512 constants will be 0 and the functions will either "croak" or fall
513 back on traditional behaviour).
514
515 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
516 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
517 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
518
519 To access higher resolution stat timestamps, see "SUBSECOND STAT
520 TIME ACCESS".
404 521
405 Example: Print the length of /etc/passwd: 522 Example: Print the length of /etc/passwd:
406 523
407 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
408 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
… …
455 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 572 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
456 Works like perl's "utime" function (including the special case of 573 Works like perl's "utime" function (including the special case of
457 $atime and $mtime being undef). Fractional times are supported if 574 $atime and $mtime being undef). Fractional times are supported if
458 the underlying syscalls support them. 575 the underlying syscalls support them.
459 576
460 When called with a pathname, uses utimes(2) if available, otherwise 577 When called with a pathname, uses utimensat(2) or utimes(2) if
461 utime(2). If called on a file descriptor, uses futimes(2) if 578 available, otherwise utime(2). If called on a file descriptor, uses
462 available, otherwise returns ENOSYS, so this is not portable. 579 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
580 this is not portable.
463 581
464 Examples: 582 Examples:
465 583
466 # set atime and mtime to current time (basically touch(1)): 584 # set atime and mtime to current time (basically touch(1)):
467 aio_utime "path", undef, undef; 585 aio_utime "path", undef, undef;
… …
481 aio_chown "path", 0, undef; 599 aio_chown "path", 0, undef;
482 600
483 aio_truncate $fh_or_path, $offset, $callback->($status) 601 aio_truncate $fh_or_path, $offset, $callback->($status)
484 Works like truncate(2) or ftruncate(2). 602 Works like truncate(2) or ftruncate(2).
485 603
604 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
605 Allocates or frees disk space according to the $mode argument. See
606 the linux "fallocate" documentation for details.
607
608 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
609 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
610 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
611
612 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
613 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
614 "FALLOC_FL_INSERT_RANGE" to insert a range and
615 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
616 fallocate(2) manpage).
617
618 The file system block size used by "fallocate" is presumably the
619 "f_bsize" returned by "statvfs", but different filesystems and
620 filetypes can dictate other limitations.
621
622 If "fallocate" isn't available or cannot be emulated (currently no
623 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
624
486 aio_chmod $fh_or_path, $mode, $callback->($status) 625 aio_chmod $fh_or_path, $mode, $callback->($status)
487 Works like perl's "chmod" function. 626 Works like perl's "chmod" function.
488 627
489 aio_unlink $pathname, $callback->($status) 628 aio_unlink $pathname, $callback->($status)
490 Asynchronously unlink (delete) a file and call the callback with the 629 Asynchronously unlink (delete) a file and call the callback with the
491 result code. 630 result code.
492 631
493 aio_mknod $path, $mode, $dev, $callback->($status) 632 aio_mknod $pathname, $mode, $dev, $callback->($status)
494 [EXPERIMENTAL] 633 [EXPERIMENTAL]
495 634
496 Asynchronously create a device node (or fifo). See mknod(2). 635 Asynchronously create a device node (or fifo). See mknod(2).
497 636
498 The only (POSIX-) portable way of calling this function is: 637 The only (POSIX-) portable way of calling this function is:
499 638
500 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 639 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
640
641 See "aio_stat" for info about some potentially helpful extra
642 constants and functions.
501 643
502 aio_link $srcpath, $dstpath, $callback->($status) 644 aio_link $srcpath, $dstpath, $callback->($status)
503 Asynchronously create a new link to the existing object at $srcpath 645 Asynchronously create a new link to the existing object at $srcpath
504 at the path $dstpath and call the callback with the result code. 646 at the path $dstpath and call the callback with the result code.
505 647
506 aio_symlink $srcpath, $dstpath, $callback->($status) 648 aio_symlink $srcpath, $dstpath, $callback->($status)
507 Asynchronously create a new symbolic link to the existing object at 649 Asynchronously create a new symbolic link to the existing object at
508 $srcpath at the path $dstpath and call the callback with the result 650 $srcpath at the path $dstpath and call the callback with the result
509 code. 651 code.
510 652
511 aio_readlink $path, $callback->($link) 653 aio_readlink $pathname, $callback->($link)
512 Asynchronously read the symlink specified by $path and pass it to 654 Asynchronously read the symlink specified by $path and pass it to
513 the callback. If an error occurs, nothing or undef gets passed to 655 the callback. If an error occurs, nothing or undef gets passed to
514 the callback. 656 the callback.
515 657
658 aio_realpath $pathname, $callback->($path)
659 Asynchronously make the path absolute and resolve any symlinks in
660 $path. The resulting path only consists of directories (same as
661 Cwd::realpath).
662
663 This request can be used to get the absolute path of the current
664 working directory by passing it a path of . (a single dot).
665
516 aio_rename $srcpath, $dstpath, $callback->($status) 666 aio_rename $srcpath, $dstpath, $callback->($status)
517 Asynchronously rename the object at $srcpath to $dstpath, just as 667 Asynchronously rename the object at $srcpath to $dstpath, just as
518 rename(2) and call the callback with the result code. 668 rename(2) and call the callback with the result code.
669
670 On systems that support the AIO::WD working directory abstraction
671 natively, the case "[$wd, "."]" as $srcpath is specialcased -
672 instead of failing, "rename" is called on the absolute path of $wd.
673
674 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
675 Basically a version of "aio_rename" with an additional $flags
676 argument. Calling this with "$flags=0" is the same as calling
677 "aio_rename".
678
679 Non-zero flags are currently only supported on GNU/Linux systems
680 that support renameat2. Other systems fail with "ENOSYS" in this
681 case.
682
683 The following constants are available (missing ones are, as usual
684 0), see renameat2(2) for details:
685
686 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
687 "IO::AIO::RENAME_WHITEOUT".
519 688
520 aio_mkdir $pathname, $mode, $callback->($status) 689 aio_mkdir $pathname, $mode, $callback->($status)
521 Asynchronously mkdir (create) a directory and call the callback with 690 Asynchronously mkdir (create) a directory and call the callback with
522 the result code. $mode will be modified by the umask at the time the 691 the result code. $mode will be modified by the umask at the time the
523 request is executed, so do not change your umask. 692 request is executed, so do not change your umask.
524 693
525 aio_rmdir $pathname, $callback->($status) 694 aio_rmdir $pathname, $callback->($status)
526 Asynchronously rmdir (delete) a directory and call the callback with 695 Asynchronously rmdir (delete) a directory and call the callback with
527 the result code. 696 the result code.
528 697
698 On systems that support the AIO::WD working directory abstraction
699 natively, the case "[$wd, "."]" is specialcased - instead of
700 failing, "rmdir" is called on the absolute path of $wd.
701
529 aio_readdir $pathname, $callback->($entries) 702 aio_readdir $pathname, $callback->($entries)
530 Unlike the POSIX call of the same name, "aio_readdir" reads an 703 Unlike the POSIX call of the same name, "aio_readdir" reads an
531 entire directory (i.e. opendir + readdir + closedir). The entries 704 entire directory (i.e. opendir + readdir + closedir). The entries
532 will not be sorted, and will NOT include the "." and ".." entries. 705 will not be sorted, and will NOT include the "." and ".." entries.
533 706
534 The callback is passed a single argument which is either "undef" or 707 The callback is passed a single argument which is either "undef" or
535 an array-ref with the filenames. 708 an array-ref with the filenames.
536 709
537 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 710 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
538 Quite similar to "aio_readdir", but the $flags argument allows to 711 Quite similar to "aio_readdir", but the $flags argument allows one
539 tune behaviour and output format. In case of an error, $entries will 712 to tune behaviour and output format. In case of an error, $entries
540 be "undef". 713 will be "undef".
541 714
542 The flags are a combination of the following constants, ORed 715 The flags are a combination of the following constants, ORed
543 together (the flags will also be passed to the callback, possibly 716 together (the flags will also be passed to the callback, possibly
544 modified): 717 modified):
545 718
546 IO::AIO::READDIR_DENTS 719 IO::AIO::READDIR_DENTS
547 When this flag is off, then the callback gets an arrayref with 720 Normally the callback gets an arrayref consisting of names only
548 of names only (as with "aio_readdir"), otherwise it gets an 721 (as with "aio_readdir"). If this flag is set, then the callback
549 arrayref with "[$name, $type, $inode]" arrayrefs, each 722 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
550 describing a single directory entry in more detail. 723 describing a single directory entry in more detail:
551 724
552 $name is the name of the entry. 725 $name is the name of the entry.
553 726
554 $type is one of the "IO::AIO::DT_xxx" constants: 727 $type is one of the "IO::AIO::DT_xxx" constants:
555 728
556 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 729 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
557 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 730 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
558 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 731 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
559 732
560 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 733 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
561 you need to know, you have to run stat yourself. Also, for speed 734 you need to know, you have to run stat yourself. Also, for
562 reasons, the $type scalars are read-only: you can not modify 735 speed/memory reasons, the $type scalars are read-only: you must
563 them. 736 not modify them.
564 737
565 $inode is the inode number (which might not be exact on systems 738 $inode is the inode number (which might not be exact on systems
566 with 64 bit inode numbers and 32 bit perls). This field has 739 with 64 bit inode numbers and 32 bit perls). This field has
567 unspecified content on systems that do not deliver the inode 740 unspecified content on systems that do not deliver the inode
568 information. 741 information.
569 742
570 IO::AIO::READDIR_DIRS_FIRST 743 IO::AIO::READDIR_DIRS_FIRST
571 When this flag is set, then the names will be returned in an 744 When this flag is set, then the names will be returned in an
572 order where likely directories come first. This is useful when 745 order where likely directories come first, in optimal stat
573 you need to quickly find directories, or you want to find all 746 order. This is useful when you need to quickly find directories,
574 directories while avoiding to stat() each entry. 747 or you want to find all directories while avoiding to stat()
748 each entry.
575 749
576 If the system returns type information in readdir, then this is 750 If the system returns type information in readdir, then this is
577 used to find directories directly. Otherwise, likely directories 751 used to find directories directly. Otherwise, likely directories
578 are files beginning with ".", or otherwise files with no dots, 752 are names beginning with ".", or otherwise names with no dots,
579 of which files with short names are tried first. 753 of which names with short names are tried first.
580 754
581 IO::AIO::READDIR_STAT_ORDER 755 IO::AIO::READDIR_STAT_ORDER
582 When this flag is set, then the names will be returned in an 756 When this flag is set, then the names will be returned in an
583 order suitable for stat()'ing each one. That is, when you plan 757 order suitable for stat()'ing each one. That is, when you plan
584 to stat() all files in the given directory, then the returned 758 to stat() most or all files in the given directory, then the
585 order will likely be fastest. 759 returned order will likely be faster.
586 760
587 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 761 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
588 specified, then the likely dirs come first, resulting in a less 762 specified, then the likely dirs come first, resulting in a less
589 optimal stat order. 763 optimal stat order for stat'ing all entries, but likely a more
764 optimal order for finding subdirectories.
590 765
591 IO::AIO::READDIR_FOUND_UNKNOWN 766 IO::AIO::READDIR_FOUND_UNKNOWN
592 This flag should not be set when calling "aio_readdirx". 767 This flag should not be set when calling "aio_readdirx".
593 Instead, it is being set by "aio_readdirx", when any of the 768 Instead, it is being set by "aio_readdirx", when any of the
594 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 769 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
595 flag therefore indicates that all $type's are known, which can 770 flag therefore indicates that all $type's are known, which can
596 be used to speed up some algorithms. 771 be used to speed up some algorithms.
597 772
773 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
774 Opens, reads and closes the given file. The data is put into $data,
775 which is resized as required.
776
777 If $offset is negative, then it is counted from the end of the file.
778
779 If $length is zero, then the remaining length of the file is used.
780 Also, in this case, the same limitations to modifying $data apply as
781 when IO::AIO::mmap is used, i.e. it must only be modified in-place
782 with "substr". If the size of the file is known, specifying a
783 non-zero $length results in a performance advantage.
784
785 This request is similar to the older "aio_load" request, but since
786 it is a single request, it might be more efficient to use.
787
788 Example: load /etc/passwd into $passwd.
789
790 my $passwd;
791 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
792 $_[0] >= 0
793 or die "/etc/passwd: $!\n";
794
795 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
796 print $passwd;
797 };
798 IO::AIO::flush;
799
598 aio_load $path, $data, $callback->($status) 800 aio_load $pathname, $data, $callback->($status)
599 This is a composite request that tries to fully load the given file 801 This is a composite request that tries to fully load the given file
600 into memory. Status is the same as with aio_read. 802 into memory. Status is the same as with aio_read.
803
804 Using "aio_slurp" might be more efficient, as it is a single
805 request.
601 806
602 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
603 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
604 or destination) from $srcpath to $dstpath and call the callback with 809 or destination) from $srcpath to $dstpath and call the callback with
605 a status of 0 (ok) or -1 (error, see $!). 810 a status of 0 (ok) or -1 (error, see $!).
606 811
812 Existing destination files will be truncated.
813
607 This is a composite request that creates the destination file with 814 This is a composite request that creates the destination file with
608 mode 0200 and copies the contents of the source file into it using 815 mode 0200 and copies the contents of the source file into it using
609 "aio_sendfile", followed by restoring atime, mtime, access mode and 816 "aio_sendfile", followed by restoring atime, mtime, access mode and
610 uid/gid, in that order. 817 uid/gid, in that order.
611 818
… …
620 827
621 This is a composite request that tries to rename(2) the file first; 828 This is a composite request that tries to rename(2) the file first;
622 if rename fails with "EXDEV", it copies the file with "aio_copy" 829 if rename fails with "EXDEV", it copies the file with "aio_copy"
623 and, if that is successful, unlinks the $srcpath. 830 and, if that is successful, unlinks the $srcpath.
624 831
625 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 832 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
626 Scans a directory (similar to "aio_readdir") but additionally tries 833 Scans a directory (similar to "aio_readdir") but additionally tries
627 to efficiently separate the entries of directory $path into two sets 834 to efficiently separate the entries of directory $path into two sets
628 of names, directories you can recurse into (directories), and ones 835 of names, directories you can recurse into (directories), and ones
629 you cannot recurse into (everything else, including symlinks to 836 you cannot recurse into (everything else, including symlinks to
630 directories). 837 directories).
631 838
632 "aio_scandir" is a composite request that creates of many sub 839 "aio_scandir" is a composite request that generates many sub
633 requests_ $maxreq specifies the maximum number of outstanding aio 840 requests. $maxreq specifies the maximum number of outstanding aio
634 requests that this function generates. If it is "<= 0", then a 841 requests that this function generates. If it is "<= 0", then a
635 suitable default will be chosen (currently 4). 842 suitable default will be chosen (currently 4).
636 843
637 On error, the callback is called without arguments, otherwise it 844 On error, the callback is called without arguments, otherwise it
638 receives two array-refs with path-relative entry names. 845 receives two array-refs with path-relative entry names.
… …
663 Then entries will be sorted into likely directories a non-initial 870 Then entries will be sorted into likely directories a non-initial
664 dot currently) and likely non-directories (see "aio_readdirx"). Then 871 dot currently) and likely non-directories (see "aio_readdirx"). Then
665 every entry plus an appended "/." will be "stat"'ed, likely 872 every entry plus an appended "/." will be "stat"'ed, likely
666 directories first, in order of their inode numbers. If that 873 directories first, in order of their inode numbers. If that
667 succeeds, it assumes that the entry is a directory or a symlink to 874 succeeds, it assumes that the entry is a directory or a symlink to
668 directory (which will be checked seperately). This is often faster 875 directory (which will be checked separately). This is often faster
669 than stat'ing the entry itself because filesystems might detect the 876 than stat'ing the entry itself because filesystems might detect the
670 type of the entry without reading the inode data (e.g. ext2fs 877 type of the entry without reading the inode data (e.g. ext2fs
671 filetype feature), even on systems that cannot return the filetype 878 filetype feature), even on systems that cannot return the filetype
672 information on readdir. 879 information on readdir.
673 880
… …
679 886
680 It will also likely work on non-POSIX filesystems with reduced 887 It will also likely work on non-POSIX filesystems with reduced
681 efficiency as those tend to return 0 or 1 as link counts, which 888 efficiency as those tend to return 0 or 1 as link counts, which
682 disables the directory counting heuristic. 889 disables the directory counting heuristic.
683 890
684 aio_rmtree $path, $callback->($status) 891 aio_rmtree $pathname, $callback->($status)
685 Delete a directory tree starting (and including) $path, return the 892 Delete a directory tree starting (and including) $path, return the
686 status of the final "rmdir" only. This is a composite request that 893 status of the final "rmdir" only. This is a composite request that
687 uses "aio_scandir" to recurse into and rmdir directories, and unlink 894 uses "aio_scandir" to recurse into and rmdir directories, and unlink
688 everything else. 895 everything else.
689 896
897 aio_fcntl $fh, $cmd, $arg, $callback->($status)
898 aio_ioctl $fh, $request, $buf, $callback->($status)
899 These work just like the "fcntl" and "ioctl" built-in functions,
900 except they execute asynchronously and pass the return value to the
901 callback.
902
903 Both calls can be used for a lot of things, some of which make more
904 sense to run asynchronously in their own thread, while some others
905 make less sense. For example, calls that block waiting for external
906 events, such as locking, will also lock down an I/O thread while it
907 is waiting, which can deadlock the whole I/O system. At the same
908 time, there might be no alternative to using a thread to wait.
909
910 So in general, you should only use these calls for things that do
911 (filesystem) I/O, not for things that wait for other events
912 (network, other processes), although if you are careful and know
913 what you are doing, you still can.
914
915 The following constants are available and can be used for normal
916 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
917
918 "F_DUPFD_CLOEXEC",
919
920 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
921
922 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
923 "FIDEDUPERANGE".
924
925 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
926 "F_SEAL_GROW" and "F_SEAL_WRITE".
927
928 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
929 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
930
931 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
932 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
933 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
934
935 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
936 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
937 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
938 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
939 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
940
941 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
942 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
943 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
944 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
945 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
946 "FS_XFLAG_HASATTR",
947
690 aio_sync $callback->($status) 948 aio_sync $callback->($status)
691 Asynchronously call sync and call the callback when finished. 949 Asynchronously call sync and call the callback when finished.
692 950
693 aio_fsync $fh, $callback->($status) 951 aio_fsync $fh, $callback->($status)
694 Asynchronously call fsync on the given filehandle and call the 952 Asynchronously call fsync on the given filehandle and call the
… …
698 Asynchronously call fdatasync on the given filehandle and call the 956 Asynchronously call fdatasync on the given filehandle and call the
699 callback with the fdatasync result code. 957 callback with the fdatasync result code.
700 958
701 If this call isn't available because your OS lacks it or it couldn't 959 If this call isn't available because your OS lacks it or it couldn't
702 be detected, it will be emulated by calling "fsync" instead. 960 be detected, it will be emulated by calling "fsync" instead.
961
962 aio_syncfs $fh, $callback->($status)
963 Asynchronously call the syncfs syscall to sync the filesystem
964 associated to the given filehandle and call the callback with the
965 syncfs result code. If syncfs is not available, calls sync(), but
966 returns -1 and sets errno to "ENOSYS" nevertheless.
703 967
704 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 968 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
705 Sync the data portion of the file specified by $offset and $length 969 Sync the data portion of the file specified by $offset and $length
706 to disk (but NOT the metadata), by calling the Linux-specific 970 to disk (but NOT the metadata), by calling the Linux-specific
707 sync_file_range call. If sync_file_range is not available or it 971 sync_file_range call. If sync_file_range is not available or it
… …
711 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 975 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
712 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 976 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
713 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 977 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
714 manpage for details. 978 manpage for details.
715 979
716 aio_pathsync $path, $callback->($status) 980 aio_pathsync $pathname, $callback->($status)
717 This request tries to open, fsync and close the given path. This is 981 This request tries to open, fsync and close the given path. This is
718 a composite request intended to sync directories after directory 982 a composite request intended to sync directories after directory
719 operations (E.g. rename). This might not work on all operating 983 operations (E.g. rename). This might not work on all operating
720 systems or have any specific effect, but usually it makes sure that 984 systems or have any specific effect, but usually it makes sure that
721 directory changes get written to disc. It works for anything that 985 directory changes get written to disc. It works for anything that
… …
724 Future versions of this function might fall back to other methods 988 Future versions of this function might fall back to other methods
725 when "fsync" on the directory fails (such as calling "sync"). 989 when "fsync" on the directory fails (such as calling "sync").
726 990
727 Passes 0 when everything went ok, and -1 on error. 991 Passes 0 when everything went ok, and -1 on error.
728 992
729 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, 993 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
730 $callback->($status) 994 $callback->($status)
731 This is a rather advanced IO::AIO call, which only works on 995 This is a rather advanced IO::AIO call, which only works on
732 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it 996 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
733 also works on data scalars managed by the Sys::Mmap or Mmap modules, 997 also works on data scalars managed by the Sys::Mmap or Mmap modules,
734 note that the scalar must only be modified in-place while an aio 998 note that the scalar must only be modified in-place while an aio
… …
736 1000
737 It calls the "msync" function of your OS, if available, with the 1001 It calls the "msync" function of your OS, if available, with the
738 memory area starting at $offset in the string and ending $length 1002 memory area starting at $offset in the string and ending $length
739 bytes later. If $length is negative, counts from the end, and if 1003 bytes later. If $length is negative, counts from the end, and if
740 $length is "undef", then it goes till the end of the string. The 1004 $length is "undef", then it goes till the end of the string. The
741 flags can be a combination of "IO::AIO::MS_ASYNC", 1005 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
742 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". 1006 an optional "IO::AIO::MS_INVALIDATE".
743 1007
744 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, 1008 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
745 $callback->($status) 1009 $callback->($status)
746 This is a rather advanced IO::AIO call, which works best on 1010 This is a rather advanced IO::AIO call, which works best on
747 mmap(2)ed scalars. 1011 mmap(2)ed scalars.
748 1012
749 It touches (reads or writes) all memory pages in the specified range 1013 It touches (reads or writes) all memory pages in the specified range
750 inside the scalar. All caveats and parameters are the same as for 1014 inside the scalar. All caveats and parameters are the same as for
751 "aio_msync", above, except for flags, which must be either 0 (which 1015 "aio_msync", above, except for flags, which must be either 0 (which
752 reads all pages and ensures they are instantiated) or 1016 reads all pages and ensures they are instantiated) or
753 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading 1017 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
754 and writing an octet from it, which dirties the page). 1018 and writing an octet from it, which dirties the page).
1019
1020 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1021 This is a rather advanced IO::AIO call, which works best on
1022 mmap(2)ed scalars.
1023
1024 It reads in all the pages of the underlying storage into memory (if
1025 any) and locks them, so they are not getting swapped/paged out or
1026 removed.
1027
1028 If $length is undefined, then the scalar will be locked till the
1029 end.
1030
1031 On systems that do not implement "mlock", this function returns -1
1032 and sets errno to "ENOSYS".
1033
1034 Note that the corresponding "munlock" is synchronous and is
1035 documented under "MISCELLANEOUS FUNCTIONS".
1036
1037 Example: open a file, mmap and mlock it - both will be undone when
1038 $data gets destroyed.
1039
1040 open my $fh, "<", $path or die "$path: $!";
1041 my $data;
1042 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1043 aio_mlock $data; # mlock in background
1044
1045 aio_mlockall $flags, $callback->($status)
1046 Calls the "mlockall" function with the given $flags (a combination
1047 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1048 "IO::AIO::MCL_ONFAULT").
1049
1050 On systems that do not implement "mlockall", this function returns
1051 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1052 supported by the system result in a return value of -1 with errno
1053 being set to "EINVAL".
1054
1055 Note that the corresponding "munlockall" is synchronous and is
1056 documented under "MISCELLANEOUS FUNCTIONS".
1057
1058 Example: asynchronously lock all current and future pages into
1059 memory.
1060
1061 aio_mlockall IO::AIO::MCL_FUTURE;
1062
1063 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1064 Queries the extents of the given file (by calling the Linux "FIEMAP"
1065 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1066 details). If the ioctl is not available on your OS, then this
1067 request will fail with "ENOSYS".
1068
1069 $start is the starting offset to query extents for, $length is the
1070 size of the range to query - if it is "undef", then the whole file
1071 will be queried.
1072
1073 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1074 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1075 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1076 query the data portion.
1077
1078 $count is the maximum number of extent records to return. If it is
1079 "undef", then IO::AIO queries all extents of the range. As a very
1080 special case, if it is 0, then the callback receives the number of
1081 extents instead of the extents themselves (which is unreliable, see
1082 below).
1083
1084 If an error occurs, the callback receives no arguments. The special
1085 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1086
1087 Otherwise, the callback receives an array reference with extent
1088 structures. Each extent structure is an array reference itself, with
1089 the following members:
1090
1091 [$logical, $physical, $length, $flags]
1092
1093 Flags is any combination of the following flag values (typically
1094 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1095
1096 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1097 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1098 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1099 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1100 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1101 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1102 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1103 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1104
1105 At the time of this writing (Linux 3.2), this request is unreliable
1106 unless $count is "undef", as the kernel has all sorts of bugs
1107 preventing it to return all extents of a range for files with a
1108 large number of extents. The code (only) works around all these
1109 issues if $count is "undef".
755 1110
756 aio_group $callback->(...) 1111 aio_group $callback->(...)
757 This is a very special aio request: Instead of doing something, it 1112 This is a very special aio request: Instead of doing something, it
758 is a container for other aio requests, which is useful if you want 1113 is a container for other aio requests, which is useful if you want
759 to bundle many requests into a single, composite, request with a 1114 to bundle many requests into a single, composite, request with a
… …
793 While it is theoretically handy to have simple I/O scheduling 1148 While it is theoretically handy to have simple I/O scheduling
794 requests like sleep and file handle readable/writable, the overhead 1149 requests like sleep and file handle readable/writable, the overhead
795 this creates is immense (it blocks a thread for a long time) so do 1150 this creates is immense (it blocks a thread for a long time) so do
796 not use this function except to put your application under 1151 not use this function except to put your application under
797 artificial I/O pressure. 1152 artificial I/O pressure.
1153
1154 IO::AIO::WD - multiple working directories
1155 Your process only has one current working directory, which is used by
1156 all threads. This makes it hard to use relative paths (some other
1157 component could call "chdir" at any time, and it is hard to control when
1158 the path will be used by IO::AIO).
1159
1160 One solution for this is to always use absolute paths. This usually
1161 works, but can be quite slow (the kernel has to walk the whole path on
1162 every access), and can also be a hassle to implement.
1163
1164 Newer POSIX systems have a number of functions (openat, fdopendir,
1165 futimensat and so on) that make it possible to specify working
1166 directories per operation.
1167
1168 For portability, and because the clowns who "designed", or shall I
1169 write, perpetrated this new interface were obviously half-drunk, this
1170 abstraction cannot be perfect, though.
1171
1172 IO::AIO allows you to convert directory paths into a so-called
1173 IO::AIO::WD object. This object stores the canonicalised, absolute
1174 version of the path, and on systems that allow it, also a directory file
1175 descriptor.
1176
1177 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1178 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1179 object and a pathname instead (or the IO::AIO::WD object alone, which
1180 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1181 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1182 relative to that IO::AIO::WD object.
1183
1184 For example, to get a wd object for /etc and then stat passwd inside,
1185 you would write:
1186
1187 aio_wd "/etc", sub {
1188 my $etcdir = shift;
1189
1190 # although $etcdir can be undef on error, there is generally no reason
1191 # to check for errors here, as aio_stat will fail with ENOENT
1192 # when $etcdir is undef.
1193
1194 aio_stat [$etcdir, "passwd"], sub {
1195 # yay
1196 };
1197 };
1198
1199 The fact that "aio_wd" is a request and not a normal function shows that
1200 creating an IO::AIO::WD object is itself a potentially blocking
1201 operation, which is why it is done asynchronously.
1202
1203 To stat the directory obtained with "aio_wd" above, one could write
1204 either of the following three request calls:
1205
1206 aio_lstat "/etc" , sub { ... # pathname as normal string
1207 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1208 aio_lstat $wd , sub { ... # shorthand for the previous
1209
1210 As with normal pathnames, IO::AIO keeps a copy of the working directory
1211 object and the pathname string, so you could write the following without
1212 causing any issues due to $path getting reused:
1213
1214 my $path = [$wd, undef];
1215
1216 for my $name (qw(abc def ghi)) {
1217 $path->[1] = $name;
1218 aio_stat $path, sub {
1219 # ...
1220 };
1221 }
1222
1223 There are some caveats: when directories get renamed (or deleted), the
1224 pathname string doesn't change, so will point to the new directory (or
1225 nowhere at all), while the directory fd, if available on the system,
1226 will still point to the original directory. Most functions accepting a
1227 pathname will use the directory fd on newer systems, and the string on
1228 older systems. Some functions (such as "aio_realpath") will always rely
1229 on the string form of the pathname.
1230
1231 So this functionality is mainly useful to get some protection against
1232 "chdir", to easily get an absolute path out of a relative path for
1233 future reference, and to speed up doing many operations in the same
1234 directory (e.g. when stat'ing all files in a directory).
1235
1236 The following functions implement this working directory abstraction:
1237
1238 aio_wd $pathname, $callback->($wd)
1239 Asynchonously canonicalise the given pathname and convert it to an
1240 IO::AIO::WD object representing it. If possible and supported on the
1241 system, also open a directory fd to speed up pathname resolution
1242 relative to this working directory.
1243
1244 If something goes wrong, then "undef" is passwd to the callback
1245 instead of a working directory object and $! is set appropriately.
1246 Since passing "undef" as working directory component of a pathname
1247 fails the request with "ENOENT", there is often no need for error
1248 checking in the "aio_wd" callback, as future requests using the
1249 value will fail in the expected way.
1250
1251 IO::AIO::CWD
1252 This is a compile time constant (object) that represents the process
1253 current working directory.
1254
1255 Specifying this object as working directory object for a pathname is
1256 as if the pathname would be specified directly, without a directory
1257 object. For example, these calls are functionally identical:
1258
1259 aio_stat "somefile", sub { ... };
1260 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1261
1262 To recover the path associated with an IO::AIO::WD object, you can use
1263 "aio_realpath":
1264
1265 aio_realpath $wd, sub {
1266 warn "path is $_[0]\n";
1267 };
1268
1269 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1270 sometimes, fall back to using an absolue path.
798 1271
799 IO::AIO::REQ CLASS 1272 IO::AIO::REQ CLASS
800 All non-aggregate "aio_*" functions return an object of this class when 1273 All non-aggregate "aio_*" functions return an object of this class when
801 called in non-void context. 1274 called in non-void context.
802 1275
… …
902 Sets a feeder/generator on this group: every group can have an 1375 Sets a feeder/generator on this group: every group can have an
903 attached generator that generates requests if idle. The idea behind 1376 attached generator that generates requests if idle. The idea behind
904 this is that, although you could just queue as many requests as you 1377 this is that, although you could just queue as many requests as you
905 want in a group, this might starve other requests for a potentially 1378 want in a group, this might starve other requests for a potentially
906 long time. For example, "aio_scandir" might generate hundreds of 1379 long time. For example, "aio_scandir" might generate hundreds of
907 thousands "aio_stat" requests, delaying any later requests for a 1380 thousands of "aio_stat" requests, delaying any later requests for a
908 long time. 1381 long time.
909 1382
910 To avoid this, and allow incremental generation of requests, you can 1383 To avoid this, and allow incremental generation of requests, you can
911 instead a group and set a feeder on it that generates those 1384 instead a group and set a feeder on it that generates those
912 requests. The feed callback will be called whenever there are few 1385 requests. The feed callback will be called whenever there are few
… …
954 results. 1427 results.
955 1428
956 See "poll_cb" for an example. 1429 See "poll_cb" for an example.
957 1430
958 IO::AIO::poll_cb 1431 IO::AIO::poll_cb
959 Process some outstanding events on the result pipe. You have to call 1432 Process some requests that have reached the result phase (i.e. they
960 this regularly. Returns 0 if all events could be processed, or -1 if 1433 have been executed but the results are not yet reported). You have
961 it returned earlier for whatever reason. Returns immediately when no 1434 to call this "regularly" to finish outstanding requests.
962 events are outstanding. The amount of events processed depends on
963 the settings of "IO::AIO::max_poll_req" and
964 "IO::AIO::max_poll_time".
965 1435
1436 Returns 0 if all events could be processed (or there were no events
1437 to process), or -1 if it returned earlier for whatever reason.
1438 Returns immediately when no events are outstanding. The amount of
1439 events processed depends on the settings of "IO::AIO::max_poll_req",
1440 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1441
966 If not all requests were processed for whatever reason, the 1442 If not all requests were processed for whatever reason, the poll
967 filehandle will still be ready when "poll_cb" returns, so normally 1443 file descriptor will still be ready when "poll_cb" returns, so
968 you don't have to do anything special to have it called later. 1444 normally you don't have to do anything special to have it called
1445 later.
1446
1447 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1448 becomes ready, it can be beneficial to call this function from loops
1449 which submit a lot of requests, to make sure the results get
1450 processed when they become available and not just when the loop is
1451 finished and the event loop takes over again. This function returns
1452 very fast when there are no outstanding requests.
969 1453
970 Example: Install an Event watcher that automatically calls 1454 Example: Install an Event watcher that automatically calls
971 IO::AIO::poll_cb with high priority (more examples can be found in 1455 IO::AIO::poll_cb with high priority (more examples can be found in
972 the SYNOPSIS section, at the top of this document): 1456 the SYNOPSIS section, at the top of this document):
973 1457
974 Event->io (fd => IO::AIO::poll_fileno, 1458 Event->io (fd => IO::AIO::poll_fileno,
975 poll => 'r', async => 1, 1459 poll => 'r', async => 1,
976 cb => \&IO::AIO::poll_cb); 1460 cb => \&IO::AIO::poll_cb);
977 1461
978 IO::AIO::poll_wait 1462 IO::AIO::poll_wait
979 If there are any outstanding requests and none of them in the result 1463 Wait until either at least one request is in the result phase or no
980 phase, wait till the result filehandle becomes ready for reading 1464 requests are outstanding anymore.
981 (simply does a "select" on the filehandle. This is useful if you 1465
982 want to synchronously wait for some requests to finish). 1466 This is useful if you want to synchronously wait for some requests
1467 to become ready, without actually handling them.
983 1468
984 See "nreqs" for an example. 1469 See "nreqs" for an example.
985 1470
986 IO::AIO::poll 1471 IO::AIO::poll
987 Waits until some requests have been handled. 1472 Waits until some requests have been handled.
… …
996 1481
997 Strictly equivalent to: 1482 Strictly equivalent to:
998 1483
999 IO::AIO::poll_wait, IO::AIO::poll_cb 1484 IO::AIO::poll_wait, IO::AIO::poll_cb
1000 while IO::AIO::nreqs; 1485 while IO::AIO::nreqs;
1486
1487 This function can be useful at program aborts, to make sure
1488 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1489 already calls this function on normal exits), or when you are merely
1490 using "IO::AIO" for its more advanced functions, rather than for
1491 async I/O, e.g.:
1492
1493 my ($dirs, $nondirs);
1494 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1495 IO::AIO::flush;
1496 # $dirs, $nondirs are now set
1001 1497
1002 IO::AIO::max_poll_reqs $nreqs 1498 IO::AIO::max_poll_reqs $nreqs
1003 IO::AIO::max_poll_time $seconds 1499 IO::AIO::max_poll_time $seconds
1004 These set the maximum number of requests (default 0, meaning 1500 These set the maximum number of requests (default 0, meaning
1005 infinity) that are being processed by "IO::AIO::poll_cb" in one 1501 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
1067 1563
1068 Under normal circumstances you don't need to call this function. 1564 Under normal circumstances you don't need to call this function.
1069 1565
1070 IO::AIO::max_idle $nthreads 1566 IO::AIO::max_idle $nthreads
1071 Limit the number of threads (default: 4) that are allowed to idle 1567 Limit the number of threads (default: 4) that are allowed to idle
1072 (i.e., threads that did not get a request to process within 10 1568 (i.e., threads that did not get a request to process within the idle
1073 seconds). That means if a thread becomes idle while $nthreads other 1569 timeout (default: 10 seconds). That means if a thread becomes idle
1074 threads are also idle, it will free its resources and exit. 1570 while $nthreads other threads are also idle, it will free its
1571 resources and exit.
1075 1572
1076 This is useful when you allow a large number of threads (e.g. 100 or 1573 This is useful when you allow a large number of threads (e.g. 100 or
1077 1000) to allow for extremely high load situations, but want to free 1574 1000) to allow for extremely high load situations, but want to free
1078 resources under normal circumstances (1000 threads can easily 1575 resources under normal circumstances (1000 threads can easily
1079 consume 30MB of RAM). 1576 consume 30MB of RAM).
1080 1577
1081 The default is probably ok in most situations, especially if thread 1578 The default is probably ok in most situations, especially if thread
1082 creation is fast. If thread creation is very slow on your system you 1579 creation is fast. If thread creation is very slow on your system you
1083 might want to use larger values. 1580 might want to use larger values.
1084 1581
1582 IO::AIO::idle_timeout $seconds
1583 Sets the minimum idle timeout (default 10) after which worker
1584 threads are allowed to exit. SEe "IO::AIO::max_idle".
1585
1085 IO::AIO::max_outstanding $maxreqs 1586 IO::AIO::max_outstanding $maxreqs
1587 Sets the maximum number of outstanding requests to $nreqs. If you do
1588 queue up more than this number of requests, the next call to
1589 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
1590 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1591 no longer exceeded.
1592
1593 In other words, this setting does not enforce a queue limit, but can
1594 be used to make poll functions block if the limit is exceeded.
1595
1086 This is a very bad function to use in interactive programs because 1596 This is a very bad function to use in interactive programs because
1087 it blocks, and a bad way to reduce concurrency because it is 1597 it blocks, and a bad way to reduce concurrency because it is
1088 inexact: Better use an "aio_group" together with a feed callback. 1598 inexact: Better use an "aio_group" together with a feed callback.
1089 1599
1090 Sets the maximum number of outstanding requests to $nreqs. If you do 1600 Its main use is in scripts without an event loop - when you want to
1091 queue up more than this number of requests, the next call to the 1601 stat a lot of files, you can write something like this:
1092 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
1093 function will block until the limit is no longer exceeded.
1094 1602
1095 The default value is very large, so there is no practical limit on 1603 IO::AIO::max_outstanding 32;
1604
1605 for my $path (...) {
1606 aio_stat $path , ...;
1607 IO::AIO::poll_cb;
1608 }
1609
1610 IO::AIO::flush;
1611
1612 The call to "poll_cb" inside the loop will normally return
1613 instantly, but as soon as more thna 32 reqeusts are in-flight, it
1614 will block until some requests have been handled. This keeps the
1615 loop from pushing a large number of "aio_stat" requests onto the
1616 queue.
1617
1618 The default value for "max_outstanding" is very large, so there is
1096 the number of outstanding requests. 1619 no practical limit on the number of outstanding requests.
1097
1098 You can still queue as many requests as you want. Therefore,
1099 "max_outstanding" is mainly useful in simple scripts (with low
1100 values) or as a stop gap to shield against fatal memory overflow
1101 (with large values).
1102 1620
1103 STATISTICAL INFORMATION 1621 STATISTICAL INFORMATION
1104 IO::AIO::nreqs 1622 IO::AIO::nreqs
1105 Returns the number of requests currently in the ready, execute or 1623 Returns the number of requests currently in the ready, execute or
1106 pending states (i.e. for which their callback has not been invoked 1624 pending states (i.e. for which their callback has not been invoked
… …
1117 1635
1118 IO::AIO::npending 1636 IO::AIO::npending
1119 Returns the number of requests currently in the pending state 1637 Returns the number of requests currently in the pending state
1120 (executed, but not yet processed by poll_cb). 1638 (executed, but not yet processed by poll_cb).
1121 1639
1640 SUBSECOND STAT TIME ACCESS
1641 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1642 generally find access/modification and change times with subsecond time
1643 accuracy of the system supports it, but perl's built-in functions only
1644 return the integer part.
1645
1646 The following functions return the timestamps of the most recent stat
1647 with subsecond precision on most systems and work both after
1648 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1649 value is only meaningful after a successful "stat"/"lstat" call, or
1650 during/after a successful "aio_stat"/"aio_lstat" callback.
1651
1652 This is similar to the Time::HiRes "stat" functions, but can return full
1653 resolution without rounding and work with standard perl "stat",
1654 alleviating the need to call the special "Time::HiRes" functions, which
1655 do not act like their perl counterparts.
1656
1657 On operating systems or file systems where subsecond time resolution is
1658 not supported or could not be detected, a fractional part of 0 is
1659 returned, so it is always safe to call these functions.
1660
1661 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1662 IO::AIO::st_btime
1663 Return the access, modication, change or birth time, respectively,
1664 including fractional part. Due to the limited precision of floating
1665 point, the accuracy on most platforms is only a bit better than
1666 milliseconds for times around now - see the *nsec* function family,
1667 below, for full accuracy.
1668
1669 File birth time is only available when the OS and perl support it
1670 (on FreeBSD and NetBSD at the time of this writing, although support
1671 is adaptive, so if your OS/perl gains support, IO::AIO can take
1672 advantage of it). On systems where it isn't available, 0 is
1673 currently returned, but this might change to "undef" in a future
1674 version.
1675
1676 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1677 Returns access, modification, change and birth time all in one go,
1678 and maybe more times in the future version.
1679
1680 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1681 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1682 Return the fractional access, modifcation, change or birth time, in
1683 nanoseconds, as an integer in the range 0 to 999999999.
1684
1685 Note that no accessors are provided for access, modification and
1686 change times - you need to get those from "stat _" if required ("int
1687 IO::AIO::st_atime" and so on will *not* generally give you the
1688 correct value).
1689
1690 $seconds = IO::AIO::st_btimesec
1691 The (integral) seconds part of the file birth time, if available.
1692
1693 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1694 Like the functions above, but returns all four times in one go (and
1695 maybe more in future versions).
1696
1697 $counter = IO::AIO::st_gen
1698 Returns the generation counter (in practice this is just a random
1699 number) of the file. This is only available on platforms which have
1700 this member in their "struct stat" (most BSDs at the time of this
1701 writing) and generally only to the root usert. If unsupported, 0 is
1702 returned, but this might change to "undef" in a future version.
1703
1704 Example: print the high resolution modification time of /etc, using
1705 "stat", and "IO::AIO::aio_stat".
1706
1707 if (stat "/etc") {
1708 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1709 }
1710
1711 IO::AIO::aio_stat "/etc", sub {
1712 $_[0]
1713 and return;
1714
1715 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1716 };
1717
1718 IO::AIO::flush;
1719
1720 Output of the awbove on my system, showing reduced and full accuracy:
1721
1722 stat(/etc) mtime: 1534043702.020808
1723 aio_stat(/etc) mtime: 1534043702.020807792
1724
1122 MISCELLANEOUS FUNCTIONS 1725 MISCELLANEOUS FUNCTIONS
1123 IO::AIO implements some functions that might be useful, but are not 1726 IO::AIO implements some functions that are useful when you want to use
1124 asynchronous. 1727 some "Advanced I/O" function not available to in Perl, without going the
1728 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1729 counterpart.
1730
1731 $numfd = IO::AIO::get_fdlimit
1732 Tries to find the current file descriptor limit and returns it, or
1733 "undef" and sets $! in case of an error. The limit is one larger
1734 than the highest valid file descriptor number.
1735
1736 IO::AIO::min_fdlimit [$numfd]
1737 Try to increase the current file descriptor limit(s) to at least
1738 $numfd by changing the soft or hard file descriptor resource limit.
1739 If $numfd is missing, it will try to set a very high limit, although
1740 this is not recommended when you know the actual minimum that you
1741 require.
1742
1743 If the limit cannot be raised enough, the function makes a
1744 best-effort attempt to increase the limit as much as possible, using
1745 various tricks, while still failing. You can query the resulting
1746 limit using "IO::AIO::get_fdlimit".
1747
1748 If an error occurs, returns "undef" and sets $!, otherwise returns
1749 true.
1125 1750
1126 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1127 Calls the "eio_sendfile_sync" function, which is like 1752 Calls the "eio_sendfile_sync" function, which is like
1128 "aio_sendfile", but is blocking (this makes most sense if you know 1753 "aio_sendfile", but is blocking (this makes most sense if you know
1129 the input data is likely cached already and the output filehandle is 1754 the input data is likely cached already and the output filehandle is
1130 set to non-blocking operations). 1755 set to non-blocking operations).
1131 1756
1132 Returns the number of bytes copied, or -1 on error. 1757 Returns the number of bytes copied, or -1 on error.
1133 1758
1134 IO::AIO::fadvise $fh, $offset, $len, $advice 1759 IO::AIO::fadvise $fh, $offset, $len, $advice
1135 Simply calls the "posix_fadvise" function (see it's manpage for 1760 Simply calls the "posix_fadvise" function (see its manpage for
1136 details). The following advice constants are avaiable: 1761 details). The following advice constants are available:
1137 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1762 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1138 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1763 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1139 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1764 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1140 1765
1141 On systems that do not implement "posix_fadvise", this function 1766 On systems that do not implement "posix_fadvise", this function
1142 returns ENOSYS, otherwise the return value of "posix_fadvise". 1767 returns ENOSYS, otherwise the return value of "posix_fadvise".
1143 1768
1769 IO::AIO::madvise $scalar, $offset, $len, $advice
1770 Simply calls the "posix_madvise" function (see its manpage for
1771 details). The following advice constants are available:
1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1774 "IO::AIO::MADV_DONTNEED".
1775
1776 If $offset is negative, counts from the end. If $length is negative,
1777 the remaining length of the $scalar is used. If possible, $length
1778 will be reduced to fit into the $scalar.
1779
1780 On systems that do not implement "posix_madvise", this function
1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1782
1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1785 $scalar (see its manpage for details). The following protect
1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1787 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1788
1789 If $offset is negative, counts from the end. If $length is negative,
1790 the remaining length of the $scalar is used. If possible, $length
1791 will be reduced to fit into the $scalar.
1792
1793 On systems that do not implement "mprotect", this function returns
1794 ENOSYS, otherwise the return value of "mprotect".
1795
1144 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1145 Memory-maps a file (or anonymous memory range) and attaches it to 1797 Memory-maps a file (or anonymous memory range) and attaches it to
1146 the given $scalar, which will act like a string scalar. 1798 the given $scalar, which will act like a string scalar. Returns true
1799 on success, and false otherwise.
1147 1800
1801 The scalar must exist, but its contents do not matter - this means
1802 you cannot use a nonexistant array or hash element. When in doubt,
1803 "undef" the scalar first.
1804
1148 The only operations allowed on the scalar are "substr"/"vec" that 1805 The only operations allowed on the mmapped scalar are
1149 don't change the string length, and most read-only operations such 1806 "substr"/"vec", which don't change the string length, and most
1150 as copying it or searching it with regexes and so on. 1807 read-only operations such as copying it or searching it with regexes
1808 and so on.
1151 1809
1152 Anything else is unsafe and will, at best, result in memory leaks. 1810 Anything else is unsafe and will, at best, result in memory leaks.
1153 1811
1154 The memory map associated with the $scalar is automatically removed 1812 The memory map associated with the $scalar is automatically removed
1155 when the $scalar is destroyed, or when the "IO::AIO::mmap" or 1813 when the $scalar is undef'd or destroyed, or when the
1156 "IO::AIO::munmap" functions are called. 1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1157 1815
1158 This calls the "mmap"(2) function internally. See your system's 1816 This calls the "mmap"(2) function internally. See your system's
1159 manual page for details on the $length, $prot and $flags parameters. 1817 manual page for details on the $length, $prot and $flags parameters.
1160 1818
1161 The $length must be larger than zero and smaller than the actual 1819 The $length must be larger than zero and smaller than the actual
… …
1165 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or 1823 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1166 "IO::AIO::PROT_WRITE", 1824 "IO::AIO::PROT_WRITE",
1167 1825
1168 $flags can be a combination of "IO::AIO::MAP_SHARED" or 1826 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1169 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when 1827 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1170 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" 1828 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1171 (which is set to "MAP_ANON" if your system only provides this 1829 "MAP_ANON" if your system only provides this constant),
1830 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1172 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", 1831 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1832 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1173 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or 1833 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1174 "IO::AIO::MAP_NONBLOCK" 1834 "IO::AIO::MAP_STACK".
1175 1835
1176 If $fh is "undef", then a file descriptor of -1 is passed. 1836 If $fh is "undef", then a file descriptor of -1 is passed.
1177 1837
1178 $offset is the offset from the start of the file - it generally must 1838 $offset is the offset from the start of the file - it generally must
1179 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. 1839 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
… …
1192 my $fast_md5 = md5 $data; 1852 my $fast_md5 = md5 $data;
1193 1853
1194 IO::AIO::munmap $scalar 1854 IO::AIO::munmap $scalar
1195 Removes a previous mmap and undefines the $scalar. 1855 Removes a previous mmap and undefines the $scalar.
1196 1856
1857 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1858 $new_address = 0]
1859 Calls the Linux-specific mremap(2) system call. The $scalar must
1860 have been mapped by "IO::AIO::mmap", and $flags must currently
1861 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1862
1863 Returns true if successful, and false otherwise. If the underlying
1864 mmapped region has changed address, then the true value has the
1865 numerical value 1, otherwise it has the numerical value 0:
1866
1867 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1868 or die "mremap: $!";
1869
1870 if ($success*1) {
1871 warn "scalar has chanegd address in memory\n";
1872 }
1873
1874 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1875 implemented, but not supported and might go away in a future
1876 version.
1877
1878 On systems where this call is not supported or is not emulated, this
1879 call returns falls and sets $! to "ENOSYS".
1880
1197 IO::AIO::mlockall $flags 1881 IO::AIO::mlockall $flags
1198 Calls the "mlockall" function with the given $flags (a combination 1882 Calls the "eio_mlockall_sync" function, which is like
1199 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL__FUTURE"). 1883 "aio_mlockall", but is blocking.
1200 1884
1201 On systems that do not implement "mlockall", this function returns 1885 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1202 ENOSYS, otherwise the return value of "mlockall". 1886 Calls the "munlock" function, undoing the effects of a previous
1887 "aio_mlock" call (see its description for details).
1203 1888
1204 IO::AIO::munlockall 1889 IO::AIO::munlockall
1205 Calls the "munlockall" function. 1890 Calls the "munlockall" function.
1206 1891
1207 On systems that do not implement "munlockall", this function returns 1892 On systems that do not implement "munlockall", this function returns
1208 ENOSYS, otherwise the return value of "munlockall". 1893 ENOSYS, otherwise the return value of "munlockall".
1894
1895 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1896 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1897 socket and return the new file handle on success, or sets $! and
1898 returns "undef" on error.
1899
1900 The remote name of the new socket will be stored in $sockaddr, which
1901 will be extended to allow for at least $sockaddr_maxlen octets. If
1902 the socket name does not fit into $sockaddr_maxlen octets, this is
1903 signaled by returning a longer string in $sockaddr, which might or
1904 might not be truncated.
1905
1906 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1907 $sockaddr_maxlen.
1908
1909 The main reasons to use this syscall rather than portable
1910 C«accept(2)> are that you can specify "SOCK_NONBLOCK" and/or
1911 "SOCK_CLOEXEC" flags and you can accept name-less sockets by
1912 specifying 0 for $sockaddr_maxlen, which is sadly not possible with
1913 perl's interface to "accept".
1914
1915 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1916 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1917 $w_off are "undef", then "NULL" is passed for these, otherwise they
1918 should be the file offset.
1919
1920 $r_fh and $w_fh should not refer to the same file, as splice might
1921 silently corrupt the data in this case.
1922
1923 The following symbol flag values are available:
1924 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1925 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1926
1927 See the splice(2) manpage for details.
1928
1929 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1930 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1931 description for "IO::AIO::splice" above for details.
1932
1933 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1934 Attempts to query or change the pipe buffer size. Obviously works
1935 only on pipes, and currently works only on GNU/Linux systems, and
1936 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1937 influence pipe buffer size on other systems, drop me a note.
1938
1939 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1940 This is a direct interface to the Linux pipe2(2) system call. If
1941 $flags is missing or 0, then this should be the same as a call to
1942 perl's built-in "pipe" function and create a new pipe, and works on
1943 systems that lack the pipe2 syscall. On win32, this case invokes
1944 "_pipe (..., 4096, O_BINARY)".
1945
1946 If $flags is non-zero, it tries to invoke the pipe2 system call with
1947 the given flags (Linux 2.6.27, glibc 2.9).
1948
1949 On success, the read and write file handles are returned.
1950
1951 On error, nothing will be returned. If the pipe2 syscall is missing
1952 and $flags is non-zero, fails with "ENOSYS".
1953
1954 Please refer to pipe2(2) for more info on the $flags, but at the
1955 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1956 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1957 supported.
1958
1959 Example: create a pipe race-free w.r.t. threads and fork:
1960
1961 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1962 or die "pipe2: $!\n";
1963
1964 $fh = IO::AIO::memfd_create $pathname[, $flags]
1965 This is a direct interface to the Linux memfd_create(2) system call.
1966 The (unhelpful) default for $flags is 0, but your default should be
1967 "IO::AIO::MFD_CLOEXEC".
1968
1969 On success, the new memfd filehandle is returned, otherwise returns
1970 "undef". If the memfd_create syscall is missing, fails with
1971 "ENOSYS".
1972
1973 Please refer to memfd_create(2) for more info on this call.
1974
1975 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1976 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1977
1978 Example: create a new memfd.
1979
1980 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1981 or die "m,emfd_create: $!\n";
1982 =item $fh = IO::AIO::eventfd [$initval, [$flags]]
1983
1984 This is a direct interface to the Linux eventfd(2) system call. The
1985 (unhelpful) defaults for $initval and $flags are 0 for both.
1986
1987 On success, the new eventfd filehandle is returned, otherwise
1988 returns "undef". If the eventfd syscall is missing, fails with
1989 "ENOSYS".
1990
1991 Please refer to eventfd(2) for more info on this call.
1992
1993 The following symbol flag values are available:
1994 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
1995 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
1996
1997 Example: create a new eventfd filehandle:
1998
1999 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2000 or die "eventfd: $!\n";
2001
2002 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2003 This is a direct interface to the Linux timerfd_create(2) system
2004 call. The (unhelpful) default for $flags is 0, but your default
2005 should be "IO::AIO::TFD_CLOEXEC".
2006
2007 On success, the new timerfd filehandle is returned, otherwise
2008 returns "undef". If the timerfd_create syscall is missing, fails
2009 with "ENOSYS".
2010
2011 Please refer to timerfd_create(2) for more info on this call.
2012
2013 The following $clockid values are available:
2014 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2015 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2016 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2017 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2018
2019 The following $flags values are available (Linux 2.6.27):
2020 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2021
2022 Example: create a new timerfd and set it to one-second repeated
2023 alarms, then wait for two alarms:
2024
2025 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2026 or die "timerfd_create: $!\n";
2027
2028 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2029 or die "timerfd_settime: $!\n";
2030
2031 for (1..2) {
2032 8 == sysread $fh, my $buf, 8
2033 or die "timerfd read failure\n";
2034
2035 printf "number of expirations (likely 1): %d\n",
2036 unpack "Q", $buf;
2037 }
2038
2039 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2040 $new_interval, $nbw_value
2041 This is a direct interface to the Linux timerfd_settime(2) system
2042 call. Please refer to its manpage for more info on this call.
2043
2044 The new itimerspec is specified using two (possibly fractional)
2045 second values, $new_interval and $new_value).
2046
2047 On success, the current interval and value are returned (as per
2048 "timerfd_gettime"). On failure, the empty list is returned.
2049
2050 The following $flags values are available:
2051 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2052
2053 See "IO::AIO::timerfd_create" for a full example.
2054
2055 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2056 This is a direct interface to the Linux timerfd_gettime(2) system
2057 call. Please refer to its manpage for more info on this call.
2058
2059 On success, returns the current values of interval and value for the
2060 given timerfd (as potentially fractional second values). On failure,
2061 the empty list is returned.
1209 2062
1210EVENT LOOP INTEGRATION 2063EVENT LOOP INTEGRATION
1211 It is recommended to use AnyEvent::AIO to integrate IO::AIO 2064 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1212 automatically into many event loops: 2065 automatically into many event loops:
1213 2066
… …
1236 # Danga::Socket integration 2089 # Danga::Socket integration
1237 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => 2090 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1238 \&IO::AIO::poll_cb); 2091 \&IO::AIO::poll_cb);
1239 2092
1240 FORK BEHAVIOUR 2093 FORK BEHAVIOUR
1241 This module should do "the right thing" when the process using it forks: 2094 Usage of pthreads in a program changes the semantics of fork
2095 considerably. Specifically, only async-safe functions can be called
2096 after fork. Perl doesn't know about this, so in general, you cannot call
2097 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2098 uses pthreads, so this applies, but many other extensions and (for
2099 inexplicable reasons) perl itself often is linked against pthreads, so
2100 this limitation applies to quite a lot of perls.
1242 2101
1243 Before the fork, IO::AIO enters a quiescent state where no requests can 2102 This module no longer tries to fight your OS, or POSIX. That means
1244 be added in other threads and no results will be processed. After the 2103 IO::AIO only works in the process that loaded it. Forking is fully
1245 fork the parent simply leaves the quiescent state and continues 2104 supported, but using IO::AIO in the child is not.
1246 request/result processing, while the child frees the request/result
1247 queue (so that the requests started before the fork will only be handled
1248 in the parent). Threads will be started on demand until the limit set in
1249 the parent process has been reached again.
1250 2105
1251 In short: the parent will, after a short pause, continue as if fork had 2106 You might get around by not *using* IO::AIO before (or after) forking.
1252 not been called, while the child will act as if IO::AIO has not been 2107 You could also try to call the IO::AIO::reinit function in the child:
1253 used yet. 2108
2109 IO::AIO::reinit
2110 Abandons all current requests and I/O threads and simply
2111 reinitialises all data structures. This is not an operation
2112 supported by any standards, but happens to work on GNU/Linux and
2113 some newer BSD systems.
2114
2115 The only reasonable use for this function is to call it after
2116 forking, if "IO::AIO" was used in the parent. Calling it while
2117 IO::AIO is active in the process will result in undefined behaviour.
2118 Calling it at any time will also result in any undefined (by POSIX)
2119 behaviour.
2120
2121 LINUX-SPECIFIC CALLS
2122 When a call is documented as "linux-specific" then this means it
2123 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2124 availability and compatibility of such calls regardless of the platform
2125 it is compiled on, so platforms such as FreeBSD which often implement
2126 these calls will work. When in doubt, call them and see if they fail wth
2127 "ENOSYS".
1254 2128
1255 MEMORY USAGE 2129 MEMORY USAGE
1256 Per-request usage: 2130 Per-request usage:
1257 2131
1258 Each aio request uses - depending on your architecture - around 100-200 2132 Each aio request uses - depending on your architecture - around 100-200
… …
1269 In the execution phase, some aio requests require more memory for 2143 In the execution phase, some aio requests require more memory for
1270 temporary buffers, and each thread requires a stack and other data 2144 temporary buffers, and each thread requires a stack and other data
1271 structures (usually around 16k-128k, depending on the OS). 2145 structures (usually around 16k-128k, depending on the OS).
1272 2146
1273KNOWN BUGS 2147KNOWN BUGS
1274 Known bugs will be fixed in the next release. 2148 Known bugs will be fixed in the next release :)
2149
2150KNOWN ISSUES
2151 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2152 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2153 non-created hash slots or other scalars I didn't think of. It's best to
2154 avoid such and either use scalar variables or making sure that the
2155 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2156
2157 I am not sure anything can be done about this, so this is considered a
2158 known issue, rather than a bug.
1275 2159
1276SEE ALSO 2160SEE ALSO
1277 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2161 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1278 more natural syntax. 2162 more natural syntax and IO::FDPass for file descriptor passing.
1279 2163
1280AUTHOR 2164AUTHOR
1281 Marc Lehmann <schmorp@schmorp.de> 2165 Marc Lehmann <schmorp@schmorp.de>
1282 http://home.schmorp.de/ 2166 http://home.schmorp.de/
1283 2167

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