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1NAME 1NAME
2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous/Advanced Input/Output
3 3
4SYNOPSIS 4SYNOPSIS
5 use IO::AIO; 5 use IO::AIO;
6 6
7 aio_open "/etc/passwd", O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8 my $fh = shift 8 my $fh = shift
9 or die "/etc/passwd: $!"; 9 or die "/etc/passwd: $!";
10 ... 10 ...
11 }; 11 };
12 12
… …
24 $req->cancel; # cancel request if still in queue 24 $req->cancel; # cancel request if still in queue
25 25
26 my $grp = aio_group sub { print "all stats done\n" }; 26 my $grp = aio_group sub { print "all stats done\n" };
27 add $grp aio_stat "..." for ...; 27 add $grp aio_stat "..." for ...;
28 28
29 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30 use AnyEvent::AIO;
31
32 # EV integration
33 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35 # Event integration
36 Event->io (fd => IO::AIO::poll_fileno,
37 poll => 'r',
38 cb => \&IO::AIO::poll_cb);
39
40 # Glib/Gtk2 integration
41 add_watch Glib::IO IO::AIO::poll_fileno,
42 in => sub { IO::AIO::poll_cb; 1 };
43
44 # Tk integration
45 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46 readable => \&IO::AIO::poll_cb);
47
48 # Danga::Socket integration
49 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50 \&IO::AIO::poll_cb);
51
52DESCRIPTION 29DESCRIPTION
53 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
54 operating system supports. 31 operating system supports. It is implemented as an interface to "libeio"
32 (<http://software.schmorp.de/pkg/libeio.html>).
55 33
56 Asynchronous means that operations that can normally block your program 34 Asynchronous means that operations that can normally block your program
57 (e.g. reading from disk) will be done asynchronously: the operation will 35 (e.g. reading from disk) will be done asynchronously: the operation will
58 still block, but you can do something else in the meantime. This is 36 still block, but you can do something else in the meantime. This is
59 extremely useful for programs that need to stay interactive even when 37 extremely useful for programs that need to stay interactive even when
… …
64 operations concurrently. 42 operations concurrently.
65 43
66 While most of this works on all types of file descriptors (for example 44 While most of this works on all types of file descriptors (for example
67 sockets), using these functions on file descriptors that support 45 sockets), using these functions on file descriptors that support
68 nonblocking operation (again, sockets, pipes etc.) is very inefficient. 46 nonblocking operation (again, sockets, pipes etc.) is very inefficient.
69 Use an event loop for that (such as the Event module): IO::AIO will 47 Use an event loop for that (such as the EV module): IO::AIO will
70 naturally fit into such an event loop itself. 48 naturally fit into such an event loop itself.
71 49
72 In this version, a number of threads are started that execute your 50 In this version, a number of threads are started that execute your
73 requests and signal their completion. You don't need thread support in 51 requests and signal their completion. You don't need thread support in
74 perl, and the threads created by this module will not be visible to 52 perl, and the threads created by this module will not be visible to
… …
77 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
78 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
79 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
80 using threads anyway. 58 using threads anyway.
81 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
82 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,
83 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
84 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
85 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
86 68
87 EXAMPLE 69 EXAMPLE
88 This is a simple example that uses the Event module and loads 70 This is a simple example that uses the EV module and loads /etc/passwd
89 /etc/passwd asynchronously: 71 asynchronously:
90 72
91 use Fcntl;
92 use Event; 73 use EV;
93 use IO::AIO; 74 use IO::AIO;
94 75
95 # register the IO::AIO callback with Event 76 # register the IO::AIO callback with EV
96 Event->io (fd => IO::AIO::poll_fileno, 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
97 poll => 'r',
98 cb => \&IO::AIO::poll_cb);
99 78
100 # queue the request to open /etc/passwd 79 # queue the request to open /etc/passwd
101 aio_open "/etc/passwd", O_RDONLY, 0, sub { 80 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
102 my $fh = shift 81 my $fh = shift
103 or die "error while opening: $!"; 82 or die "error while opening: $!";
104 83
105 # stat'ing filehandles is generally non-blocking 84 # stat'ing filehandles is generally non-blocking
106 my $size = -s $fh; 85 my $size = -s $fh;
… …
115 94
116 # file contents now in $contents 95 # file contents now in $contents
117 print $contents; 96 print $contents;
118 97
119 # exit event loop and program 98 # exit event loop and program
120 Event::unloop; 99 EV::break;
121 }; 100 };
122 }; 101 };
123 102
124 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
125 # check for sockets etc. etc. 104 # check for sockets etc. etc.
126 105
127 # process events as long as there are some: 106 # process events as long as there are some:
128 Event::loop; 107 EV::run;
129 108
130REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
131 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
132 not directly visible to Perl. 111 not directly visible to Perl.
133 112
… …
169 anymore (except possibly for the Perl object, but its connection to 148 anymore (except possibly for the Perl object, but its connection to
170 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
171 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
172 151
173FUNCTIONS 152FUNCTIONS
174 AIO REQUEST FUNCTIONS 153 QUICK OVERVIEW
154 This section simply lists the prototypes most of the functions for quick
155 reference. See the following sections for function-by-function
156 documentation.
157
158 aio_wd $pathname, $callback->($wd)
159 aio_open $pathname, $flags, $mode, $callback->($fh)
160 aio_close $fh, $callback->($status)
161 aio_seek $fh,$offset,$whence, $callback->($offs)
162 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
163 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
165 aio_readahead $fh,$offset,$length, $callback->($retval)
166 aio_stat $fh_or_path, $callback->($status)
167 aio_lstat $fh, $callback->($status)
168 aio_statvfs $fh_or_path, $callback->($statvfs)
169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
171 aio_chmod $fh_or_path, $mode, $callback->($status)
172 aio_truncate $fh_or_path, $offset, $callback->($status)
173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
175 aio_unlink $pathname, $callback->($status)
176 aio_mknod $pathname, $mode, $dev, $callback->($status)
177 aio_link $srcpath, $dstpath, $callback->($status)
178 aio_symlink $srcpath, $dstpath, $callback->($status)
179 aio_readlink $pathname, $callback->($link)
180 aio_realpath $pathname, $callback->($path)
181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
183 aio_mkdir $pathname, $mode, $callback->($status)
184 aio_rmdir $pathname, $callback->($status)
185 aio_readdir $pathname, $callback->($entries)
186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
188 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
190 aio_load $pathname, $data, $callback->($status)
191 aio_copy $srcpath, $dstpath, $callback->($status)
192 aio_move $srcpath, $dstpath, $callback->($status)
193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
198 aio_fsync $fh, $callback->($status)
199 aio_fdatasync $fh, $callback->($status)
200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
201 aio_pathsync $pathname, $callback->($status)
202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
205 aio_mlockall $flags, $callback->($status)
206 aio_group $callback->(...)
207 aio_nop $callback->()
208
209 $prev_pri = aioreq_pri [$pri]
210 aioreq_nice $pri_adjust
211
212 IO::AIO::poll_wait
213 IO::AIO::poll_cb
214 IO::AIO::poll
215 IO::AIO::flush
216 IO::AIO::max_poll_reqs $nreqs
217 IO::AIO::max_poll_time $seconds
218 IO::AIO::min_parallel $nthreads
219 IO::AIO::max_parallel $nthreads
220 IO::AIO::max_idle $nthreads
221 IO::AIO::idle_timeout $seconds
222 IO::AIO::max_outstanding $maxreqs
223 IO::AIO::nreqs
224 IO::AIO::nready
225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
230
231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
232 IO::AIO::fadvise $fh, $offset, $len, $advice
233
234 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
235 IO::AIO::munmap $scalar
236 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
237 IO::AIO::madvise $scalar, $offset, $length, $advice
238 IO::AIO::mprotect $scalar, $offset, $length, $protect
239 IO::AIO::munlock $scalar, $offset = 0, $length = undef
240 IO::AIO::munlockall
241
242 # stat extensions
243 $counter = IO::AIO::st_gen
244 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
245 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
246 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
247 $seconds = IO::AIO::st_btimesec
248 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
249
250 # very much unportable syscalls
251 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
252 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
253 IO::AIO::tee $r_fh, $w_fh, $length, $flags
254 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
255 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
256 $fh = IO::AIO::memfd_create $pathname[, $flags]
257 $fh = IO::AIO::eventfd [$initval, [$flags]]
258 $fh = IO::AIO::timerfd_create $clockid[, $flags]
259 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
260 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
261
262 API NOTES
175 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
176 with the same name (sans "aio_"). The arguments are similar or 264 with the same name (sans "aio_"). The arguments are similar or
177 identical, and they all accept an additional (and optional) $callback 265 identical, and they all accept an additional (and optional) $callback
178 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
179 called with the syscall return code (e.g. most syscalls return -1 on
180 error, unlike perl, which usually delivers "false") as its sole argument
181 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".
182 275
183 All functions expecting a filehandle keep a copy of the filehandle 276 All functions expecting a filehandle keep a copy of the filehandle
184 internally until the request has finished. 277 internally until the request has finished.
185 278
186 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
187 further manipulation of those requests while they are in-flight. 280 further manipulation of those requests while they are in-flight.
188 281
189 The pathnames you pass to these routines *must* be absolute and encoded 282 The pathnames you pass to these routines *should* be absolute. The
190 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
191 being executed, the current working directory could have changed. 284 current working directory could have changed. Alternatively, you can
192 Alternatively, you can make sure that you never change the current 285 make sure that you never change the current working directory anywhere
193 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.
194 290
195 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
196 pass in filenames you got from outside (command line, readdir etc.) 292 pass in filenames you got from outside (command line, readdir etc.)
197 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
198 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)
199 the user environment, d) use Glib::filename_from_unicode on unicode 295 encoding in effect in the user environment, d) use
200 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
201 contents. 297 else to ensure your scalar has the correct contents.
202 298
203 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
204 handles correctly whether it is set or not. 300 handles correctly whether it is set or not.
205 301
302 AIO REQUEST FUNCTIONS
206 $prev_pri = aioreq_pri [$pri] 303 $prev_pri = aioreq_pri [$pri]
207 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
208 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.
209 306
210 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
… …
232 Similar to "aioreq_pri", but subtracts the given value from the 329 Similar to "aioreq_pri", but subtracts the given value from the
233 current priority, so the effect is cumulative. 330 current priority, so the effect is cumulative.
234 331
235 aio_open $pathname, $flags, $mode, $callback->($fh) 332 aio_open $pathname, $flags, $mode, $callback->($fh)
236 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
237 newly created filehandle for the file. 334 newly created filehandle for the file (or "undef" in case of an
335 error).
238 336
239 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,
240 above, for an explanation. 338 above, for an explanation.
241 339
242 The $flags argument is a bitmask. See the "Fcntl" module for a list. 340 The $flags argument is a bitmask. See the "Fcntl" module for a list.
… …
249 will be modified by the umask in effect then the request is being 347 will be modified by the umask in effect then the request is being
250 executed, so better never change the umask. 348 executed, so better never change the umask.
251 349
252 Example: 350 Example:
253 351
254 aio_open "/etc/passwd", O_RDONLY, 0, sub { 352 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
255 if ($_[0]) { 353 if ($_[0]) {
256 print "open successful, fh is $_[0]\n"; 354 print "open successful, fh is $_[0]\n";
257 ... 355 ...
258 } else { 356 } else {
259 die "open failed: $!\n"; 357 die "open failed: $!\n";
260 } 358 }
261 }; 359 };
262 360
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
263 aio_close $fh, $callback->($status) 371 aio_close $fh, $callback->($status)
264 Asynchronously close a file and call the callback with the result 372 Asynchronously close a file and call the callback with the result
265 code. 373 code.
266 374
267 Unfortunately, you can't do this to perl. Perl *insists* very 375 Unfortunately, you can't do this to perl. Perl *insists* very
… …
273 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).
274 382
275 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
276 not be free for reuse until the perl filehandle is closed. 384 not be free for reuse until the perl filehandle is closed.
277 385
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".
404
278 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 405 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 406 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280 Reads or writes $length bytes from the specified $fh and $offset 407 Reads or writes $length bytes from or to the specified $fh and
281 into the scalar given by $data and offset $dataoffset and calls the 408 $offset into the scalar given by $data and offset $dataoffset and
282 callback without the actual number of bytes read (or -1 on error, 409 calls the callback with the actual number of bytes transferred (or
283 just like the syscall). 410 -1 on error, just like the syscall).
411
412 "aio_read" will, like "sysread", shrink or grow the $data scalar to
413 offset plus the actual number of bytes read.
284 414
285 If $offset is undefined, then the current file descriptor offset 415 If $offset is undefined, then the current file descriptor offset
286 will be used (and updated), otherwise the file descriptor offset 416 will be used (and updated), otherwise the file descriptor offset
287 will not be changed by these calls. 417 will not be changed by these calls.
288 418
… …
307 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 437 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
308 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
309 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
310 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
311 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
312 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.
313 444
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
314 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
315 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
316 to a socket, and $in_fh should refer to mmap'able file. 464 to a socket, and $in_fh should refer to an mmap'able file.
317 465
318 If the native sendfile call fails or is not implemented, it will be 466 If a native sendfile cannot be found or it fails with "ENOSYS",
319 emulated, so you can call "aio_sendfile" on any type of filehandle 467 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
320 regardless of the limitations of the operating system. 468 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
469 any type of filehandle regardless of the limitations of the
470 operating system.
321 471
322 Please note, however, that "aio_sendfile" can read more bytes from 472 As native sendfile syscalls (as practically any non-POSIX interface
323 $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
324 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 474 rather buggy on many systems, this implementation tries to work
325 only provides the number of bytes written to $out_fh. Only if the 475 around some known bugs in Linux and FreeBSD kernels (probably
326 result value equals $length one can assume that $length bytes have 476 others, too), but that might fail, so you really really should check
327 been read. 477 the return value of "aio_sendfile" - fewer bytes than expected might
478 have been transferred.
328 479
329 aio_readahead $fh,$offset,$length, $callback->($retval) 480 aio_readahead $fh,$offset,$length, $callback->($retval)
330 "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
331 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
332 $offset argument specifies the starting point from which data is to 483 $offset argument specifies the starting point from which data is to
… …
335 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
336 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
337 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
338 is left unchanged. 489 is left unchanged.
339 490
340 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
341 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
342 similar effect. 493 similar effect.
343 494
344 aio_stat $fh_or_path, $callback->($status) 495 aio_stat $fh_or_path, $callback->($status)
345 aio_lstat $fh, $callback->($status) 496 aio_lstat $fh, $callback->($status)
346 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.
347 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
348 using "stat _" or "-s _" etc... 499 available using "stat _" or "-s _" and other tests (with the
500 exception of "-B" and "-T").
349 501
350 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,
351 above, for an explanation. 503 above, for an explanation.
352 504
353 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
354 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
355 silently truncated unless perl itself is compiled with large file 507 silently truncated unless perl itself is compiled with large file
356 support. 508 support.
357 509
510 To help interpret the mode and dev/rdev stat values, IO::AIO offers
511 the following constants and functions (if not implemented, the
512 constants will be 0 and the functions will either "croak" or fall
513 back on traditional behaviour).
514
515 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
516 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
517 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
518
519 To access higher resolution stat timestamps, see "SUBSECOND STAT
520 TIME ACCESS".
521
358 Example: Print the length of /etc/passwd: 522 Example: Print the length of /etc/passwd:
359 523
360 aio_stat "/etc/passwd", sub { 524 aio_stat "/etc/passwd", sub {
361 $_[0] and die "stat failed: $!"; 525 $_[0] and die "stat failed: $!";
362 print "size is ", -s _, "\n"; 526 print "size is ", -s _, "\n";
363 }; 527 };
364 528
529 aio_statvfs $fh_or_path, $callback->($statvfs)
530 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
531 whether a file handle or path was passed.
532
533 On success, the callback is passed a hash reference with the
534 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
535 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
536 failure, "undef" is passed.
537
538 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
539 and "ST_NOSUID".
540
541 The following non-POSIX IO::AIO::ST_* flag masks are defined to
542 their correct value when available, or to 0 on systems that do not
543 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
544 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
545 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
546
547 Example: stat "/wd" and dump out the data if successful.
548
549 aio_statvfs "/wd", sub {
550 my $f = $_[0]
551 or die "statvfs: $!";
552
553 use Data::Dumper;
554 say Dumper $f;
555 };
556
557 # result:
558 {
559 bsize => 1024,
560 bfree => 4333064312,
561 blocks => 10253828096,
562 files => 2050765568,
563 flag => 4096,
564 favail => 2042092649,
565 bavail => 4333064312,
566 ffree => 2042092649,
567 namemax => 255,
568 frsize => 1024,
569 fsid => 1810
570 }
571
365 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 572 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
366 Works like perl's "utime" function (including the special case of 573 Works like perl's "utime" function (including the special case of
367 $atime and $mtime being undef). Fractional times are supported if 574 $atime and $mtime being undef). Fractional times are supported if
368 the underlying syscalls support them. 575 the underlying syscalls support them.
369 576
370 When called with a pathname, uses utimes(2) if available, otherwise 577 When called with a pathname, uses utimensat(2) or utimes(2) if
371 utime(2). If called on a file descriptor, uses futimes(2) if 578 available, otherwise utime(2). If called on a file descriptor, uses
372 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.
373 581
374 Examples: 582 Examples:
375 583
376 # set atime and mtime to current time (basically touch(1)): 584 # set atime and mtime to current time (basically touch(1)):
377 aio_utime "path", undef, undef; 585 aio_utime "path", undef, undef;
… …
391 aio_chown "path", 0, undef; 599 aio_chown "path", 0, undef;
392 600
393 aio_truncate $fh_or_path, $offset, $callback->($status) 601 aio_truncate $fh_or_path, $offset, $callback->($status)
394 Works like truncate(2) or ftruncate(2). 602 Works like truncate(2) or ftruncate(2).
395 603
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
396 aio_chmod $fh_or_path, $mode, $callback->($status) 625 aio_chmod $fh_or_path, $mode, $callback->($status)
397 Works like perl's "chmod" function. 626 Works like perl's "chmod" function.
398 627
399 aio_unlink $pathname, $callback->($status) 628 aio_unlink $pathname, $callback->($status)
400 Asynchronously unlink (delete) a file and call the callback with the 629 Asynchronously unlink (delete) a file and call the callback with the
401 result code. 630 result code.
402 631
403 aio_mknod $path, $mode, $dev, $callback->($status) 632 aio_mknod $pathname, $mode, $dev, $callback->($status)
404 [EXPERIMENTAL] 633 [EXPERIMENTAL]
405 634
406 Asynchronously create a device node (or fifo). See mknod(2). 635 Asynchronously create a device node (or fifo). See mknod(2).
407 636
408 The only (POSIX-) portable way of calling this function is: 637 The only (POSIX-) portable way of calling this function is:
409 638
410 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.
411 643
412 aio_link $srcpath, $dstpath, $callback->($status) 644 aio_link $srcpath, $dstpath, $callback->($status)
413 Asynchronously create a new link to the existing object at $srcpath 645 Asynchronously create a new link to the existing object at $srcpath
414 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.
415 647
416 aio_symlink $srcpath, $dstpath, $callback->($status) 648 aio_symlink $srcpath, $dstpath, $callback->($status)
417 Asynchronously create a new symbolic link to the existing object at 649 Asynchronously create a new symbolic link to the existing object at
418 $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
419 code. 651 code.
420 652
421 aio_readlink $path, $callback->($link) 653 aio_readlink $pathname, $callback->($link)
422 Asynchronously read the symlink specified by $path and pass it to 654 Asynchronously read the symlink specified by $path and pass it to
423 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
424 the callback. 656 the callback.
425 657
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
426 aio_rename $srcpath, $dstpath, $callback->($status) 666 aio_rename $srcpath, $dstpath, $callback->($status)
427 Asynchronously rename the object at $srcpath to $dstpath, just as 667 Asynchronously rename the object at $srcpath to $dstpath, just as
428 rename(2) and call the callback with the result code. 668 rename(2) and call the callback with the result code.
669
670 On systems that support the AIO::WD working directory abstraction
671 natively, the case "[$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".
429 688
430 aio_mkdir $pathname, $mode, $callback->($status) 689 aio_mkdir $pathname, $mode, $callback->($status)
431 Asynchronously mkdir (create) a directory and call the callback with 690 Asynchronously mkdir (create) a directory and call the callback with
432 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
433 request is executed, so do not change your umask. 692 request is executed, so do not change your umask.
434 693
435 aio_rmdir $pathname, $callback->($status) 694 aio_rmdir $pathname, $callback->($status)
436 Asynchronously rmdir (delete) a directory and call the callback with 695 Asynchronously rmdir (delete) a directory and call the callback with
437 the result code. 696 the result code.
438 697
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
439 aio_readdir $pathname, $callback->($entries) 702 aio_readdir $pathname, $callback->($entries)
440 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
441 entire directory (i.e. opendir + readdir + closedir). The entries 704 entire directory (i.e. opendir + readdir + closedir). The entries
442 will not be sorted, and will NOT include the "." and ".." entries. 705 will not be sorted, and will NOT include the "." and ".." entries.
443 706
444 The callback a single argument which is either "undef" or an 707 The callback is passed a single argument which is either "undef" or
445 array-ref with the filenames. 708 an array-ref with the filenames.
446 709
710 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
711 Quite similar to "aio_readdir", but the $flags argument allows one
712 to tune behaviour and output format. In case of an error, $entries
713 will be "undef".
714
715 The flags are a combination of the following constants, ORed
716 together (the flags will also be passed to the callback, possibly
717 modified):
718
719 IO::AIO::READDIR_DENTS
720 Normally the callback gets an arrayref consisting of names only
721 (as with "aio_readdir"). If this flag is set, then the callback
722 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
723 describing a single directory entry in more detail:
724
725 $name is the name of the entry.
726
727 $type is one of the "IO::AIO::DT_xxx" constants:
728
729 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
730 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
731 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
732
733 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
734 you need to know, you have to run stat yourself. Also, for
735 speed/memory reasons, the $type scalars are read-only: you must
736 not modify them.
737
738 $inode is the inode number (which might not be exact on systems
739 with 64 bit inode numbers and 32 bit perls). This field has
740 unspecified content on systems that do not deliver the inode
741 information.
742
743 IO::AIO::READDIR_DIRS_FIRST
744 When this flag is set, then the names will be returned in an
745 order where likely directories come first, in optimal stat
746 order. This is useful when you need to quickly find directories,
747 or you want to find all directories while avoiding to stat()
748 each entry.
749
750 If the system returns type information in readdir, then this is
751 used to find directories directly. Otherwise, likely directories
752 are names beginning with ".", or otherwise names with no dots,
753 of which names with short names are tried first.
754
755 IO::AIO::READDIR_STAT_ORDER
756 When this flag is set, then the names will be returned in an
757 order suitable for stat()'ing each one. That is, when you plan
758 to stat() most or all files in the given directory, then the
759 returned order will likely be faster.
760
761 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
762 specified, then the likely dirs come first, resulting in a less
763 optimal stat order for stat'ing all entries, but likely a more
764 optimal order for finding subdirectories.
765
766 IO::AIO::READDIR_FOUND_UNKNOWN
767 This flag should not be set when calling "aio_readdirx".
768 Instead, it is being set by "aio_readdirx", when any of the
769 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
770 flag therefore indicates that all $type's are known, which can
771 be used to speed up some algorithms.
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
447 aio_load $path, $data, $callback->($status) 800 aio_load $pathname, $data, $callback->($status)
448 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
449 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.
450 806
451 aio_copy $srcpath, $dstpath, $callback->($status) 807 aio_copy $srcpath, $dstpath, $callback->($status)
452 Try to copy the *file* (directories not supported as either source 808 Try to copy the *file* (directories not supported as either source
453 or destination) from $srcpath to $dstpath and call the callback with 809 or destination) from $srcpath to $dstpath and call the callback with
454 the 0 (error) or -1 ok. 810 a status of 0 (ok) or -1 (error, see $!).
811
812 Existing destination files will be truncated.
455 813
456 This is a composite request that creates the destination file with 814 This is a composite request that creates the destination file with
457 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
458 "aio_sendfile", followed by restoring atime, mtime, access mode and 816 "aio_sendfile", followed by restoring atime, mtime, access mode and
459 uid/gid, in that order. 817 uid/gid, in that order.
… …
463 uid/gid, where errors are being ignored. 821 uid/gid, where errors are being ignored.
464 822
465 aio_move $srcpath, $dstpath, $callback->($status) 823 aio_move $srcpath, $dstpath, $callback->($status)
466 Try to move the *file* (directories not supported as either source 824 Try to move the *file* (directories not supported as either source
467 or destination) from $srcpath to $dstpath and call the callback with 825 or destination) from $srcpath to $dstpath and call the callback with
468 the 0 (error) or -1 ok. 826 a status of 0 (ok) or -1 (error, see $!).
469 827
470 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;
471 If rename files with "EXDEV", it copies the file with "aio_copy" 829 if rename fails with "EXDEV", it copies the file with "aio_copy"
472 and, if that is successful, unlinking the $srcpath. 830 and, if that is successful, unlinks the $srcpath.
473 831
474 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 832 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
475 Scans a directory (similar to "aio_readdir") but additionally tries 833 Scans a directory (similar to "aio_readdir") but additionally tries
476 to efficiently separate the entries of directory $path into two sets 834 to efficiently separate the entries of directory $path into two sets
477 of names, directories you can recurse into (directories), and ones 835 of names, directories you can recurse into (directories), and ones
478 you cannot recurse into (everything else, including symlinks to 836 you cannot recurse into (everything else, including symlinks to
479 directories). 837 directories).
480 838
481 "aio_scandir" is a composite request that creates of many sub 839 "aio_scandir" is a composite request that generates many sub
482 requests_ $maxreq specifies the maximum number of outstanding aio 840 requests. $maxreq specifies the maximum number of outstanding aio
483 requests that this function generates. If it is "<= 0", then a 841 requests that this function generates. If it is "<= 0", then a
484 suitable default will be chosen (currently 4). 842 suitable default will be chosen (currently 4).
485 843
486 On error, the callback is called without arguments, otherwise it 844 On error, the callback is called without arguments, otherwise it
487 receives two array-refs with path-relative entry names. 845 receives two array-refs with path-relative entry names.
… …
497 Implementation notes. 855 Implementation notes.
498 856
499 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry 857 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
500 can. 858 can.
501 859
860 If readdir returns file type information, then this is used directly
861 to find directories.
862
502 After reading the directory, the modification time, size etc. of the 863 Otherwise, after reading the directory, the modification time, size
503 directory before and after the readdir is checked, and if they match 864 etc. of the directory before and after the readdir is checked, and
504 (and isn't the current time), the link count will be used to decide 865 if they match (and isn't the current time), the link count will be
505 how many entries are directories (if >= 2). Otherwise, no knowledge 866 used to decide how many entries are directories (if >= 2).
506 of the number of subdirectories will be assumed. 867 Otherwise, no knowledge of the number of subdirectories will be
868 assumed.
507 869
508 Then entries will be sorted into likely directories (everything 870 Then entries will be sorted into likely directories a non-initial
509 without a non-initial dot currently) and likely non-directories 871 dot currently) and likely non-directories (see "aio_readdirx"). Then
510 (everything else). Then every entry plus an appended "/." will be 872 every entry plus an appended "/." will be "stat"'ed, likely
511 "stat"'ed, likely directories first. If that succeeds, it assumes 873 directories first, in order of their inode numbers. If that
512 that the entry is a directory or a symlink to directory (which will 874 succeeds, it assumes that the entry is a directory or a symlink to
513 be checked seperately). This is often faster than stat'ing the entry 875 directory (which will be checked separately). This is often faster
514 itself because filesystems might detect the type of the entry 876 than stat'ing the entry itself because filesystems might detect the
515 without reading the inode data (e.g. ext2fs filetype feature). 877 type of the entry without reading the inode data (e.g. ext2fs
878 filetype feature), even on systems that cannot return the filetype
879 information on readdir.
516 880
517 If the known number of directories (link count - 2) has been 881 If the known number of directories (link count - 2) has been
518 reached, the rest of the entries is assumed to be non-directories. 882 reached, the rest of the entries is assumed to be non-directories.
519 883
520 This only works with certainty on POSIX (= UNIX) filesystems, which 884 This only works with certainty on POSIX (= UNIX) filesystems, which
… …
522 886
523 It will also likely work on non-POSIX filesystems with reduced 887 It will also likely work on non-POSIX filesystems with reduced
524 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
525 disables the directory counting heuristic. 889 disables the directory counting heuristic.
526 890
527 aio_rmtree $path, $callback->($status) 891 aio_rmtree $pathname, $callback->($status)
528 Delete a directory tree starting (and including) $path, return the 892 Delete a directory tree starting (and including) $path, return the
529 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
530 uses "aio_scandir" to recurse into and rmdir directories, and unlink 894 uses "aio_scandir" to recurse into and rmdir directories, and unlink
531 everything else. 895 everything else.
532 896
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
533 aio_sync $callback->($status) 948 aio_sync $callback->($status)
534 Asynchronously call sync and call the callback when finished. 949 Asynchronously call sync and call the callback when finished.
535 950
536 aio_fsync $fh, $callback->($status) 951 aio_fsync $fh, $callback->($status)
537 Asynchronously call fsync on the given filehandle and call the 952 Asynchronously call fsync on the given filehandle and call the
… …
542 callback with the fdatasync result code. 957 callback with the fdatasync result code.
543 958
544 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
545 be detected, it will be emulated by calling "fsync" instead. 960 be detected, it will be emulated by calling "fsync" instead.
546 961
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.
967
968 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
969 Sync the data portion of the file specified by $offset and $length
970 to disk (but NOT the metadata), by calling the Linux-specific
971 sync_file_range call. If sync_file_range is not available or it
972 returns ENOSYS, then fdatasync or fsync is being substituted.
973
974 $flags can be a combination of
975 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
976 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
977 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
978 manpage for details.
979
547 aio_pathsync $path, $callback->($status) 980 aio_pathsync $pathname, $callback->($status)
548 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
549 a composite request intended to sync directories after directory 982 a composite request intended to sync directories after directory
550 operations (E.g. rename). This might not work on all operating 983 operations (E.g. rename). This might not work on all operating
551 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
552 directory changes get written to disc. It works for anything that 985 directory changes get written to disc. It works for anything that
553 can be opened for read-only, not just directories. 986 can be opened for read-only, not just directories.
554 987
988 Future versions of this function might fall back to other methods
989 when "fsync" on the directory fails (such as calling "sync").
990
555 Passes 0 when everything went ok, and -1 on error. 991 Passes 0 when everything went ok, and -1 on error.
992
993 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
994 $callback->($status)
995 This is a rather advanced IO::AIO call, which only works on
996 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
997 also works on data scalars managed by the Sys::Mmap or Mmap modules,
998 note that the scalar must only be modified in-place while an aio
999 operation is pending on it).
1000
1001 It calls the "msync" function of your OS, if available, with the
1002 memory area starting at $offset in the string and ending $length
1003 bytes later. If $length is negative, counts from the end, and if
1004 $length is "undef", then it goes till the end of the string. The
1005 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
1006 an optional "IO::AIO::MS_INVALIDATE".
1007
1008 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
1009 $callback->($status)
1010 This is a rather advanced IO::AIO call, which works best on
1011 mmap(2)ed scalars.
1012
1013 It touches (reads or writes) all memory pages in the specified range
1014 inside the scalar. All caveats and parameters are the same as for
1015 "aio_msync", above, except for flags, which must be either 0 (which
1016 reads all pages and ensures they are instantiated) or
1017 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
1018 and writing an octet from it, which dirties the page).
1019
1020 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1021 This is a rather advanced IO::AIO call, which works best on
1022 mmap(2)ed scalars.
1023
1024 It reads in all the pages of the underlying storage into memory (if
1025 any) and locks them, so they are not getting swapped/paged out or
1026 removed.
1027
1028 If $length is undefined, then the scalar will be locked till the
1029 end.
1030
1031 On systems that do not implement "mlock", this function returns -1
1032 and sets errno to "ENOSYS".
1033
1034 Note that the corresponding "munlock" is synchronous and is
1035 documented under "MISCELLANEOUS FUNCTIONS".
1036
1037 Example: open a file, mmap and mlock it - both will be undone when
1038 $data gets destroyed.
1039
1040 open my $fh, "<", $path or die "$path: $!";
1041 my $data;
1042 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1043 aio_mlock $data; # mlock in background
1044
1045 aio_mlockall $flags, $callback->($status)
1046 Calls the "mlockall" function with the given $flags (a combination
1047 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1048 "IO::AIO::MCL_ONFAULT").
1049
1050 On systems that do not implement "mlockall", this function returns
1051 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1052 supported by the system result in a return value of -1 with errno
1053 being set to "EINVAL".
1054
1055 Note that the corresponding "munlockall" is synchronous and is
1056 documented under "MISCELLANEOUS FUNCTIONS".
1057
1058 Example: asynchronously lock all current and future pages into
1059 memory.
1060
1061 aio_mlockall IO::AIO::MCL_FUTURE;
1062
1063 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1064 Queries the extents of the given file (by calling the Linux "FIEMAP"
1065 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1066 details). If the ioctl is not available on your OS, then this
1067 request will fail with "ENOSYS".
1068
1069 $start is the starting offset to query extents for, $length is the
1070 size of the range to query - if it is "undef", then the whole file
1071 will be queried.
1072
1073 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1074 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1075 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1076 query the data portion.
1077
1078 $count is the maximum number of extent records to return. If it is
1079 "undef", then IO::AIO queries all extents of the range. As a very
1080 special case, if it is 0, then the callback receives the number of
1081 extents instead of the extents themselves (which is unreliable, see
1082 below).
1083
1084 If an error occurs, the callback receives no arguments. The special
1085 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1086
1087 Otherwise, the callback receives an array reference with extent
1088 structures. Each extent structure is an array reference itself, with
1089 the following members:
1090
1091 [$logical, $physical, $length, $flags]
1092
1093 Flags is any combination of the following flag values (typically
1094 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1095
1096 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1097 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1098 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1099 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1100 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1101 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1102 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1103 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1104
1105 At the time of this writing (Linux 3.2), this request is unreliable
1106 unless $count is "undef", as the kernel has all sorts of bugs
1107 preventing it to return all extents of a range for files with a
1108 large number of extents. The code (only) works around all these
1109 issues if $count is "undef".
556 1110
557 aio_group $callback->(...) 1111 aio_group $callback->(...)
558 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
559 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
560 to bundle many requests into a single, composite, request with a 1114 to bundle many requests into a single, composite, request with a
… …
595 requests like sleep and file handle readable/writable, the overhead 1149 requests like sleep and file handle readable/writable, the overhead
596 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
597 not use this function except to put your application under 1151 not use this function except to put your application under
598 artificial I/O pressure. 1152 artificial I/O pressure.
599 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.
1271
600 IO::AIO::REQ CLASS 1272 IO::AIO::REQ CLASS
601 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
602 called in non-void context. 1274 called in non-void context.
603 1275
604 cancel $req 1276 cancel $req
605 Cancels the request, if possible. Has the effect of skipping 1277 Cancels the request, if possible. Has the effect of skipping
606 execution when entering the execute state and skipping calling the 1278 execution when entering the execute state and skipping calling the
607 callback when entering the the result state, but will leave the 1279 callback when entering the the result state, but will leave the
608 request otherwise untouched. That means that requests that currently 1280 request otherwise untouched (with the exception of readdir). That
609 execute will not be stopped and resources held by the request will 1281 means that requests that currently execute will not be stopped and
610 not be freed prematurely. 1282 resources held by the request will not be freed prematurely.
611 1283
612 cb $req $callback->(...) 1284 cb $req $callback->(...)
613 Replace (or simply set) the callback registered to the request. 1285 Replace (or simply set) the callback registered to the request.
614 1286
615 IO::AIO::GRP CLASS 1287 IO::AIO::GRP CLASS
… …
676 1348
677 $grp->cancel_subs 1349 $grp->cancel_subs
678 Cancel all subrequests and clears any feeder, but not the group 1350 Cancel all subrequests and clears any feeder, but not the group
679 request itself. Useful when you queued a lot of events but got a 1351 request itself. Useful when you queued a lot of events but got a
680 result early. 1352 result early.
1353
1354 The group request will finish normally (you cannot add requests to
1355 the group).
681 1356
682 $grp->result (...) 1357 $grp->result (...)
683 Set the result value(s) that will be passed to the group callback 1358 Set the result value(s) that will be passed to the group callback
684 when all subrequests have finished and set the groups errno to the 1359 when all subrequests have finished and set the groups errno to the
685 current value of errno (just like calling "errno" without an error 1360 current value of errno (just like calling "errno" without an error
… …
700 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
701 attached generator that generates requests if idle. The idea behind 1376 attached generator that generates requests if idle. The idea behind
702 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
703 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
704 long time. For example, "aio_scandir" might generate hundreds of 1379 long time. For example, "aio_scandir" might generate hundreds of
705 thousands "aio_stat" requests, delaying any later requests for a 1380 thousands of "aio_stat" requests, delaying any later requests for a
706 long time. 1381 long time.
707 1382
708 To avoid this, and allow incremental generation of requests, you can 1383 To avoid this, and allow incremental generation of requests, you can
709 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
710 requests. The feed callback will be called whenever there are few 1385 requests. The feed callback will be called whenever there are few
… …
715 does not impose any limits). 1390 does not impose any limits).
716 1391
717 If the feed does not queue more requests when called, it will be 1392 If the feed does not queue more requests when called, it will be
718 automatically removed from the group. 1393 automatically removed from the group.
719 1394
720 If the feed limit is 0, it will be set to 2 automatically. 1395 If the feed limit is 0 when this method is called, it will be set to
1396 2 automatically.
721 1397
722 Example: 1398 Example:
723 1399
724 # stat all files in @files, but only ever use four aio requests concurrently: 1400 # stat all files in @files, but only ever use four aio requests concurrently:
725 1401
… …
736 Sets the feeder limit for the group: The feeder will be called 1412 Sets the feeder limit for the group: The feeder will be called
737 whenever the group contains less than this many requests. 1413 whenever the group contains less than this many requests.
738 1414
739 Setting the limit to 0 will pause the feeding process. 1415 Setting the limit to 0 will pause the feeding process.
740 1416
1417 The default value for the limit is 0, but note that setting a feeder
1418 automatically bumps it up to 2.
1419
741 SUPPORT FUNCTIONS 1420 SUPPORT FUNCTIONS
742 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1421 EVENT PROCESSING AND EVENT LOOP INTEGRATION
743 $fileno = IO::AIO::poll_fileno 1422 $fileno = IO::AIO::poll_fileno
744 Return the *request result pipe file descriptor*. This filehandle 1423 Return the *request result pipe file descriptor*. This filehandle
745 must be polled for reading by some mechanism outside this module 1424 must be polled for reading by some mechanism outside this module
746 (e.g. Event or select, see below or the SYNOPSIS). If the pipe 1425 (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
747 becomes readable you have to call "poll_cb" to check the results. 1426 pipe becomes readable you have to call "poll_cb" to check the
1427 results.
748 1428
749 See "poll_cb" for an example. 1429 See "poll_cb" for an example.
750 1430
751 IO::AIO::poll_cb 1431 IO::AIO::poll_cb
752 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
753 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
754 it returned earlier for whatever reason. Returns immediately when no 1434 to call this "regularly" to finish outstanding requests.
755 events are outstanding. The amount of events processed depends on
756 the settings of "IO::AIO::max_poll_req" and
757 "IO::AIO::max_poll_time".
758 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
759 If not all requests were processed for whatever reason, the 1442 If not all requests were processed for whatever reason, the poll
760 filehandle will still be ready when "poll_cb" returns, so normally 1443 file descriptor will still be ready when "poll_cb" returns, so
761 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.
762 1453
763 Example: Install an Event watcher that automatically calls 1454 Example: Install an Event watcher that automatically calls
764 IO::AIO::poll_cb with high priority: 1455 IO::AIO::poll_cb with high priority (more examples can be found in
1456 the SYNOPSIS section, at the top of this document):
765 1457
766 Event->io (fd => IO::AIO::poll_fileno, 1458 Event->io (fd => IO::AIO::poll_fileno,
767 poll => 'r', async => 1, 1459 poll => 'r', async => 1,
768 cb => \&IO::AIO::poll_cb); 1460 cb => \&IO::AIO::poll_cb);
1461
1462 IO::AIO::poll_wait
1463 Wait until either at least one request is in the result phase or no
1464 requests are outstanding anymore.
1465
1466 This is useful if you want to synchronously wait for some requests
1467 to become ready, without actually handling them.
1468
1469 See "nreqs" for an example.
1470
1471 IO::AIO::poll
1472 Waits until some requests have been handled.
1473
1474 Returns the number of requests processed, but is otherwise strictly
1475 equivalent to:
1476
1477 IO::AIO::poll_wait, IO::AIO::poll_cb
1478
1479 IO::AIO::flush
1480 Wait till all outstanding AIO requests have been handled.
1481
1482 Strictly equivalent to:
1483
1484 IO::AIO::poll_wait, IO::AIO::poll_cb
1485 while IO::AIO::nreqs;
1486
1487 This function can be useful at program aborts, to make sure
1488 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1489 already calls this function on normal exits), or when you are merely
1490 using "IO::AIO" for its more advanced functions, rather than for
1491 async I/O, e.g.:
1492
1493 my ($dirs, $nondirs);
1494 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1495 IO::AIO::flush;
1496 # $dirs, $nondirs are now set
769 1497
770 IO::AIO::max_poll_reqs $nreqs 1498 IO::AIO::max_poll_reqs $nreqs
771 IO::AIO::max_poll_time $seconds 1499 IO::AIO::max_poll_time $seconds
772 These set the maximum number of requests (default 0, meaning 1500 These set the maximum number of requests (default 0, meaning
773 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
… …
797 # use a low priority so other tasks have priority 1525 # use a low priority so other tasks have priority
798 Event->io (fd => IO::AIO::poll_fileno, 1526 Event->io (fd => IO::AIO::poll_fileno,
799 poll => 'r', nice => 1, 1527 poll => 'r', nice => 1,
800 cb => &IO::AIO::poll_cb); 1528 cb => &IO::AIO::poll_cb);
801 1529
802 IO::AIO::poll_wait
803 If there are any outstanding requests and none of them in the result
804 phase, wait till the result filehandle becomes ready for reading
805 (simply does a "select" on the filehandle. This is useful if you
806 want to synchronously wait for some requests to finish).
807
808 See "nreqs" for an example.
809
810 IO::AIO::poll
811 Waits until some requests have been handled.
812
813 Returns the number of requests processed, but is otherwise strictly
814 equivalent to:
815
816 IO::AIO::poll_wait, IO::AIO::poll_cb
817
818 IO::AIO::flush
819 Wait till all outstanding AIO requests have been handled.
820
821 Strictly equivalent to:
822
823 IO::AIO::poll_wait, IO::AIO::poll_cb
824 while IO::AIO::nreqs;
825
826 CONTROLLING THE NUMBER OF THREADS 1530 CONTROLLING THE NUMBER OF THREADS
827 IO::AIO::min_parallel $nthreads 1531 IO::AIO::min_parallel $nthreads
828 Set the minimum number of AIO threads to $nthreads. The current 1532 Set the minimum number of AIO threads to $nthreads. The current
829 default is 8, which means eight asynchronous operations can execute 1533 default is 8, which means eight asynchronous operations can execute
830 concurrently at any one time (the number of outstanding requests, 1534 concurrently at any one time (the number of outstanding requests,
… …
859 1563
860 Under normal circumstances you don't need to call this function. 1564 Under normal circumstances you don't need to call this function.
861 1565
862 IO::AIO::max_idle $nthreads 1566 IO::AIO::max_idle $nthreads
863 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
864 (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
865 seconds). That means if a thread becomes idle while $nthreads other 1569 timeout (default: 10 seconds). That means if a thread becomes idle
866 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.
867 1572
868 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
869 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
870 resources under normal circumstances (1000 threads can easily 1575 resources under normal circumstances (1000 threads can easily
871 consume 30MB of RAM). 1576 consume 30MB of RAM).
872 1577
873 The default is probably ok in most situations, especially if thread 1578 The default is probably ok in most situations, especially if thread
874 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
875 might want to use larger values. 1580 might want to use larger values.
876 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
877 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
878 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
879 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
880 inexact: Better use an "aio_group" together with a feed callback. 1598 inexact: Better use an "aio_group" together with a feed callback.
881 1599
882 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
883 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:
884 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
885 function will block until the limit is no longer exceeded.
886 1602
887 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
888 the number of outstanding requests. 1619 no practical limit on the number of outstanding requests.
889
890 You can still queue as many requests as you want. Therefore,
891 "max_outstanding" is mainly useful in simple scripts (with low
892 values) or as a stop gap to shield against fatal memory overflow
893 (with large values).
894 1620
895 STATISTICAL INFORMATION 1621 STATISTICAL INFORMATION
896 IO::AIO::nreqs 1622 IO::AIO::nreqs
897 Returns the number of requests currently in the ready, execute or 1623 Returns the number of requests currently in the ready, execute or
898 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
… …
909 1635
910 IO::AIO::npending 1636 IO::AIO::npending
911 Returns the number of requests currently in the pending state 1637 Returns the number of requests currently in the pending state
912 (executed, but not yet processed by poll_cb). 1638 (executed, but not yet processed by poll_cb).
913 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
1725 MISCELLANEOUS FUNCTIONS
1726 IO::AIO implements some functions that are useful when you want to use
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.
1750
1751 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1752 Calls the "eio_sendfile_sync" function, which is like
1753 "aio_sendfile", but is blocking (this makes most sense if you know
1754 the input data is likely cached already and the output filehandle is
1755 set to non-blocking operations).
1756
1757 Returns the number of bytes copied, or -1 on error.
1758
1759 IO::AIO::fadvise $fh, $offset, $len, $advice
1760 Simply calls the "posix_fadvise" function (see its manpage for
1761 details). The following advice constants are available:
1762 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1763 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1764 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1765
1766 On systems that do not implement "posix_fadvise", this function
1767 returns ENOSYS, otherwise the return value of "posix_fadvise".
1768
1769 IO::AIO::madvise $scalar, $offset, $len, $advice
1770 Simply calls the "posix_madvise" function (see its manpage for
1771 details). The following advice constants are available:
1772 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1773 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1774 "IO::AIO::MADV_DONTNEED".
1775
1776 If $offset is negative, counts from the end. If $length is negative,
1777 the remaining length of the $scalar is used. If possible, $length
1778 will be reduced to fit into the $scalar.
1779
1780 On systems that do not implement "posix_madvise", this function
1781 returns ENOSYS, otherwise the return value of "posix_madvise".
1782
1783 IO::AIO::mprotect $scalar, $offset, $len, $protect
1784 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1785 $scalar (see its manpage for details). The following protect
1786 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1787 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1788
1789 If $offset is negative, counts from the end. If $length is negative,
1790 the remaining length of the $scalar is used. If possible, $length
1791 will be reduced to fit into the $scalar.
1792
1793 On systems that do not implement "mprotect", this function returns
1794 ENOSYS, otherwise the return value of "mprotect".
1795
1796 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1797 Memory-maps a file (or anonymous memory range) and attaches it to
1798 the given $scalar, which will act like a string scalar. Returns true
1799 on success, and false otherwise.
1800
1801 The scalar must exist, but its contents do not matter - this means
1802 you cannot use a nonexistant array or hash element. When in doubt,
1803 "undef" the scalar first.
1804
1805 The only operations allowed on the mmapped scalar are
1806 "substr"/"vec", which don't change the string length, and most
1807 read-only operations such as copying it or searching it with regexes
1808 and so on.
1809
1810 Anything else is unsafe and will, at best, result in memory leaks.
1811
1812 The memory map associated with the $scalar is automatically removed
1813 when the $scalar is undef'd or destroyed, or when the
1814 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1815
1816 This calls the "mmap"(2) function internally. See your system's
1817 manual page for details on the $length, $prot and $flags parameters.
1818
1819 The $length must be larger than zero and smaller than the actual
1820 filesize.
1821
1822 $prot is a combination of "IO::AIO::PROT_NONE",
1823 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1824 "IO::AIO::PROT_WRITE",
1825
1826 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1827 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1828 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1829 "MAP_ANON" if your system only provides this constant),
1830 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1831 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1832 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1833 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1834 "IO::AIO::MAP_STACK".
1835
1836 If $fh is "undef", then a file descriptor of -1 is passed.
1837
1838 $offset is the offset from the start of the file - it generally must
1839 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1840
1841 Example:
1842
1843 use Digest::MD5;
1844 use IO::AIO;
1845
1846 open my $fh, "<verybigfile"
1847 or die "$!";
1848
1849 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1850 or die "verybigfile: $!";
1851
1852 my $fast_md5 = md5 $data;
1853
1854 IO::AIO::munmap $scalar
1855 Removes a previous mmap and undefines the $scalar.
1856
1857 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1858 $new_address = 0]
1859 Calls the Linux-specific mremap(2) system call. The $scalar must
1860 have been mapped by "IO::AIO::mmap", and $flags must currently
1861 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1862
1863 Returns true if successful, and false otherwise. If the underlying
1864 mmapped region has changed address, then the true value has the
1865 numerical value 1, otherwise it has the numerical value 0:
1866
1867 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1868 or die "mremap: $!";
1869
1870 if ($success*1) {
1871 warn "scalar has chanegd address in memory\n";
1872 }
1873
1874 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1875 implemented, but not supported and might go away in a future
1876 version.
1877
1878 On systems where this call is not supported or is not emulated, this
1879 call returns falls and sets $! to "ENOSYS".
1880
1881 IO::AIO::mlockall $flags
1882 Calls the "eio_mlockall_sync" function, which is like
1883 "aio_mlockall", but is blocking.
1884
1885 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1886 Calls the "munlock" function, undoing the effects of a previous
1887 "aio_mlock" call (see its description for details).
1888
1889 IO::AIO::munlockall
1890 Calls the "munlockall" function.
1891
1892 On systems that do not implement "munlockall", this function returns
1893 ENOSYS, otherwise the return value of "munlockall".
1894
1895 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1896 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1897 socket and return the new file handle on success, or sets $! and
1898 returns "undef" on error.
1899
1900 The remote name of the new socket will be stored in $sockaddr, which
1901 will be extended to allow for at least $sockaddr_maxlen octets. If
1902 the socket name does not fit into $sockaddr_maxlen octets, this is
1903 signaled by returning a longer string in $sockaddr, which might or
1904 might not be truncated.
1905
1906 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1907 $sockaddr_maxlen.
1908
1909 The main reasons to use this syscall rather than portable accept(2)
1910 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1911 and you can accept name-less sockets by specifying 0 for
1912 $sockaddr_maxlen, which is sadly not possible with perl's interface
1913 to "accept".
1914
1915 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1916 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1917 $w_off are "undef", then "NULL" is passed for these, otherwise they
1918 should be the file offset.
1919
1920 $r_fh and $w_fh should not refer to the same file, as splice might
1921 silently corrupt the data in this case.
1922
1923 The following symbol flag values are available:
1924 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1925 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1926
1927 See the splice(2) manpage for details.
1928
1929 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1930 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1931 description for "IO::AIO::splice" above for details.
1932
1933 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1934 Attempts to query or change the pipe buffer size. Obviously works
1935 only on pipes, and currently works only on GNU/Linux systems, and
1936 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1937 influence pipe buffer size on other systems, drop me a note.
1938
1939 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1940 This is a direct interface to the Linux pipe2(2) system call. If
1941 $flags is missing or 0, then this should be the same as a call to
1942 perl's built-in "pipe" function and create a new pipe, and works on
1943 systems that lack the pipe2 syscall. On win32, this case invokes
1944 "_pipe (..., 4096, O_BINARY)".
1945
1946 If $flags is non-zero, it tries to invoke the pipe2 system call with
1947 the given flags (Linux 2.6.27, glibc 2.9).
1948
1949 On success, the read and write file handles are returned.
1950
1951 On error, nothing will be returned. If the pipe2 syscall is missing
1952 and $flags is non-zero, fails with "ENOSYS".
1953
1954 Please refer to pipe2(2) for more info on the $flags, but at the
1955 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
1956 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
1957 supported.
1958
1959 Example: create a pipe race-free w.r.t. threads and fork:
1960
1961 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
1962 or die "pipe2: $!\n";
1963
1964 $fh = IO::AIO::memfd_create $pathname[, $flags]
1965 This is a direct interface to the Linux memfd_create(2) system call.
1966 The (unhelpful) default for $flags is 0, but your default should be
1967 "IO::AIO::MFD_CLOEXEC".
1968
1969 On success, the new memfd filehandle is returned, otherwise returns
1970 "undef". If the memfd_create syscall is missing, fails with
1971 "ENOSYS".
1972
1973 Please refer to memfd_create(2) for more info on this call.
1974
1975 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
1976 "IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
1977
1978 Example: create a new memfd.
1979
1980 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
1981 or die "memfd_create: $!\n";
1982
1983 $fh = IO::AIO::pidfd_open $pid[, $flags]
1984 This is an interface to the Linux pidfd_open(2) system call. The
1985 default for $flags is 0.
1986
1987 On success, a new pidfd filehandle is returned (that is already set
1988 to close-on-exec), otherwise returns "undef". If the syscall is
1989 missing, fails with "ENOSYS".
1990
1991 Example: open pid 6341 as pidfd.
1992
1993 my $fh = IO::AIO::pidfd_open 6341
1994 or die "pidfd_open: $!\n";
1995
1996 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
1997 $flags]]
1998 This is an interface to the Linux pidfd_send_signal system call. The
1999 default for $siginfo is "undef" and the default for $flags is 0.
2000
2001 Returns the system call status. If the syscall is missing, fails
2002 with "ENOSYS".
2003
2004 When specified, $siginfo must be a reference to a hash with one or
2005 more of the following members:
2006
2007 code - the "si_code" member
2008 pid - the "si_pid" member
2009 uid - the "si_uid" member
2010 value_int - the "si_value.sival_int" member
2011 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2012
2013 Example: send a SIGKILL to the specified process.
2014
2015 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2016 and die "pidfd_send_signal: $!\n";
2017
2018 Example: send a SIGKILL to the specified process with extra data.
2019
2020 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2021 and die "pidfd_send_signal: $!\n";
2022
2023 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2024 This is an interface to the Linux pidfd_getfd system call. The
2025 default for $flags is 0.
2026
2027 On success, returns a dup'ed copy of the target file descriptor
2028 (specified as an integer) returned (that is already set to
2029 close-on-exec), otherwise returns "undef". If the syscall is
2030 missing, fails with "ENOSYS".
2031
2032 Example: get a copy of standard error of another process and print
2033 soemthing to it.
2034
2035 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2036 or die "pidfd_getfd: $!\n";
2037 print $errfh "stderr\n";
2038
2039 $fh = IO::AIO::eventfd [$initval, [$flags]]
2040 This is a direct interface to the Linux eventfd(2) system call. The
2041 (unhelpful) defaults for $initval and $flags are 0 for both.
2042
2043 On success, the new eventfd filehandle is returned, otherwise
2044 returns "undef". If the eventfd syscall is missing, fails with
2045 "ENOSYS".
2046
2047 Please refer to eventfd(2) for more info on this call.
2048
2049 The following symbol flag values are available:
2050 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2051 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2052
2053 Example: create a new eventfd filehandle:
2054
2055 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2056 or die "eventfd: $!\n";
2057
2058 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2059 This is a direct interface to the Linux timerfd_create(2) system
2060 call. The (unhelpful) default for $flags is 0, but your default
2061 should be "IO::AIO::TFD_CLOEXEC".
2062
2063 On success, the new timerfd filehandle is returned, otherwise
2064 returns "undef". If the timerfd_create syscall is missing, fails
2065 with "ENOSYS".
2066
2067 Please refer to timerfd_create(2) for more info on this call.
2068
2069 The following $clockid values are available:
2070 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2071 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2072 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2073 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2074
2075 The following $flags values are available (Linux 2.6.27):
2076 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2077
2078 Example: create a new timerfd and set it to one-second repeated
2079 alarms, then wait for two alarms:
2080
2081 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2082 or die "timerfd_create: $!\n";
2083
2084 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2085 or die "timerfd_settime: $!\n";
2086
2087 for (1..2) {
2088 8 == sysread $fh, my $buf, 8
2089 or die "timerfd read failure\n";
2090
2091 printf "number of expirations (likely 1): %d\n",
2092 unpack "Q", $buf;
2093 }
2094
2095 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2096 $new_interval, $nbw_value
2097 This is a direct interface to the Linux timerfd_settime(2) system
2098 call. Please refer to its manpage for more info on this call.
2099
2100 The new itimerspec is specified using two (possibly fractional)
2101 second values, $new_interval and $new_value).
2102
2103 On success, the current interval and value are returned (as per
2104 "timerfd_gettime"). On failure, the empty list is returned.
2105
2106 The following $flags values are available:
2107 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2108
2109 See "IO::AIO::timerfd_create" for a full example.
2110
2111 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2112 This is a direct interface to the Linux timerfd_gettime(2) system
2113 call. Please refer to its manpage for more info on this call.
2114
2115 On success, returns the current values of interval and value for the
2116 given timerfd (as potentially fractional second values). On failure,
2117 the empty list is returned.
2118
2119EVENT LOOP INTEGRATION
2120 It is recommended to use AnyEvent::AIO to integrate IO::AIO
2121 automatically into many event loops:
2122
2123 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
2124 use AnyEvent::AIO;
2125
2126 You can also integrate IO::AIO manually into many event loops, here are
2127 some examples of how to do this:
2128
2129 # EV integration
2130 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
2131
2132 # Event integration
2133 Event->io (fd => IO::AIO::poll_fileno,
2134 poll => 'r',
2135 cb => \&IO::AIO::poll_cb);
2136
2137 # Glib/Gtk2 integration
2138 add_watch Glib::IO IO::AIO::poll_fileno,
2139 in => sub { IO::AIO::poll_cb; 1 };
2140
2141 # Tk integration
2142 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
2143 readable => \&IO::AIO::poll_cb);
2144
2145 # Danga::Socket integration
2146 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
2147 \&IO::AIO::poll_cb);
2148
914 FORK BEHAVIOUR 2149 FORK BEHAVIOUR
915 This module should do "the right thing" when the process using it forks: 2150 Usage of pthreads in a program changes the semantics of fork
2151 considerably. Specifically, only async-safe functions can be called
2152 after fork. Perl doesn't know about this, so in general, you cannot call
2153 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2154 uses pthreads, so this applies, but many other extensions and (for
2155 inexplicable reasons) perl itself often is linked against pthreads, so
2156 this limitation applies to quite a lot of perls.
916 2157
917 Before the fork, IO::AIO enters a quiescent state where no requests can 2158 This module no longer tries to fight your OS, or POSIX. That means
918 be added in other threads and no results will be processed. After the 2159 IO::AIO only works in the process that loaded it. Forking is fully
919 fork the parent simply leaves the quiescent state and continues 2160 supported, but using IO::AIO in the child is not.
920 request/result processing, while the child frees the request/result
921 queue (so that the requests started before the fork will only be handled
922 in the parent). Threads will be started on demand until the limit set in
923 the parent process has been reached again.
924 2161
925 In short: the parent will, after a short pause, continue as if fork had 2162 You might get around by not *using* IO::AIO before (or after) forking.
926 not been called, while the child will act as if IO::AIO has not been 2163 You could also try to call the IO::AIO::reinit function in the child:
927 used yet. 2164
2165 IO::AIO::reinit
2166 Abandons all current requests and I/O threads and simply
2167 reinitialises all data structures. This is not an operation
2168 supported by any standards, but happens to work on GNU/Linux and
2169 some newer BSD systems.
2170
2171 The only reasonable use for this function is to call it after
2172 forking, if "IO::AIO" was used in the parent. Calling it while
2173 IO::AIO is active in the process will result in undefined behaviour.
2174 Calling it at any time will also result in any undefined (by POSIX)
2175 behaviour.
2176
2177 LINUX-SPECIFIC CALLS
2178 When a call is documented as "linux-specific" then this means it
2179 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2180 availability and compatibility of such calls regardless of the platform
2181 it is compiled on, so platforms such as FreeBSD which often implement
2182 these calls will work. When in doubt, call them and see if they fail wth
2183 "ENOSYS".
928 2184
929 MEMORY USAGE 2185 MEMORY USAGE
930 Per-request usage: 2186 Per-request usage:
931 2187
932 Each aio request uses - depending on your architecture - around 100-200 2188 Each aio request uses - depending on your architecture - around 100-200
… …
943 In the execution phase, some aio requests require more memory for 2199 In the execution phase, some aio requests require more memory for
944 temporary buffers, and each thread requires a stack and other data 2200 temporary buffers, and each thread requires a stack and other data
945 structures (usually around 16k-128k, depending on the OS). 2201 structures (usually around 16k-128k, depending on the OS).
946 2202
947KNOWN BUGS 2203KNOWN BUGS
948 Known bugs will be fixed in the next release. 2204 Known bugs will be fixed in the next release :)
2205
2206KNOWN ISSUES
2207 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2208 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2209 non-created hash slots or other scalars I didn't think of. It's best to
2210 avoid such and either use scalar variables or making sure that the
2211 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2212
2213 I am not sure anything can be done about this, so this is considered a
2214 known issue, rather than a bug.
949 2215
950SEE ALSO 2216SEE ALSO
951 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2217 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
952 more natural syntax. 2218 more natural syntax and IO::FDPass for file descriptor passing.
953 2219
954AUTHOR 2220AUTHOR
955 Marc Lehmann <schmorp@schmorp.de> 2221 Marc Lehmann <schmorp@schmorp.de>
956 http://home.schmorp.de/ 2222 http://home.schmorp.de/
957 2223

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