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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 IO::AIO::fexecve $fh, $argv, $envp
234
235 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
236 IO::AIO::munmap $scalar
237 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
238 IO::AIO::madvise $scalar, $offset, $length, $advice
239 IO::AIO::mprotect $scalar, $offset, $length, $protect
240 IO::AIO::munlock $scalar, $offset = 0, $length = undef
241 IO::AIO::munlockall
242
243 # stat extensions
244 $counter = IO::AIO::st_gen
245 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
246 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
247 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
248 $seconds = IO::AIO::st_btimesec
249 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
250
251 # very much unportable syscalls
252 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
253 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
254 IO::AIO::tee $r_fh, $w_fh, $length, $flags
255
256 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
257 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
258
259 $fh = IO::AIO::eventfd [$initval, [$flags]]
260 $fh = IO::AIO::memfd_create $pathname[, $flags]
261
262 $fh = IO::AIO::timerfd_create $clockid[, $flags]
263 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
264 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
265
266 $fh = IO::AIO::pidfd_open $pid[, $flags]
267 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
268 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
269
270 $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
271 $retval = IO::AIO::umount $path, $flags = 0
272
273 API NOTES
175 All the "aio_*" calls are more or less thin wrappers around the syscall 274 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 275 with the same name (sans "aio_"). The arguments are similar or
177 identical, and they all accept an additional (and optional) $callback 276 identical, and they all accept an additional (and optional) $callback
178 argument which must be a code reference. This code reference will get 277 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. 278 called after the syscall has been executed in an asynchronous fashion.
279 The results of the request will be passed as arguments to the callback
280 (and, if an error occured, in $!) - for most requests the syscall return
281 code (e.g. most syscalls return -1 on error, unlike perl, which usually
282 delivers "false").
283
284 Some requests (such as "aio_readdir") pass the actual results and
285 communicate failures by passing "undef".
182 286
183 All functions expecting a filehandle keep a copy of the filehandle 287 All functions expecting a filehandle keep a copy of the filehandle
184 internally until the request has finished. 288 internally until the request has finished.
185 289
186 All functions return request objects of type IO::AIO::REQ that allow 290 All functions return request objects of type IO::AIO::REQ that allow
187 further manipulation of those requests while they are in-flight. 291 further manipulation of those requests while they are in-flight.
188 292
189 The pathnames you pass to these routines *must* be absolute and encoded 293 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 294 reason for this is that at the time the request is being executed, the
191 being executed, the current working directory could have changed. 295 current working directory could have changed. Alternatively, you can
192 Alternatively, you can make sure that you never change the current 296 make sure that you never change the current working directory anywhere
193 working directory anywhere in the program and then use relative paths. 297 in the program and then use relative paths. You can also take advantage
298 of IO::AIOs working directory abstraction, that lets you specify paths
299 relative to some previously-opened "working directory object" - see the
300 description of the "IO::AIO::WD" class later in this document.
194 301
195 To encode pathnames as octets, either make sure you either: a) always 302 To encode pathnames as octets, either make sure you either: a) always
196 pass in filenames you got from outside (command line, readdir etc.) 303 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 304 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 305 Encode module and encode your pathnames to the locale (or other)
199 the user environment, d) use Glib::filename_from_unicode on unicode 306 encoding in effect in the user environment, d) use
200 filenames or e) use something else to ensure your scalar has the correct 307 Glib::filename_from_unicode on unicode filenames or e) use something
201 contents. 308 else to ensure your scalar has the correct contents.
202 309
203 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 310 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
204 handles correctly whether it is set or not. 311 handles correctly whether it is set or not.
205 312
313 AIO REQUEST FUNCTIONS
206 $prev_pri = aioreq_pri [$pri] 314 $prev_pri = aioreq_pri [$pri]
207 Returns the priority value that would be used for the next request 315 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. 316 and, if $pri is given, sets the priority for the next aio request.
209 317
210 The default priority is 0, the minimum and maximum priorities are -4 318 The default priority is 0, the minimum and maximum priorities are -4
… …
232 Similar to "aioreq_pri", but subtracts the given value from the 340 Similar to "aioreq_pri", but subtracts the given value from the
233 current priority, so the effect is cumulative. 341 current priority, so the effect is cumulative.
234 342
235 aio_open $pathname, $flags, $mode, $callback->($fh) 343 aio_open $pathname, $flags, $mode, $callback->($fh)
236 Asynchronously open or create a file and call the callback with a 344 Asynchronously open or create a file and call the callback with a
237 newly created filehandle for the file. 345 newly created filehandle for the file (or "undef" in case of an
238 346 error).
239 The pathname passed to "aio_open" must be absolute. See API NOTES,
240 above, for an explanation.
241 347
242 The $flags argument is a bitmask. See the "Fcntl" module for a list. 348 The $flags argument is a bitmask. See the "Fcntl" module for a list.
243 They are the same as used by "sysopen". 349 They are the same as used by "sysopen".
244 350
245 Likewise, $mode specifies the mode of the newly created file, if it 351 Likewise, $mode specifies the mode of the newly created file, if it
… …
249 will be modified by the umask in effect then the request is being 355 will be modified by the umask in effect then the request is being
250 executed, so better never change the umask. 356 executed, so better never change the umask.
251 357
252 Example: 358 Example:
253 359
254 aio_open "/etc/passwd", O_RDONLY, 0, sub { 360 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
255 if ($_[0]) { 361 if ($_[0]) {
256 print "open successful, fh is $_[0]\n"; 362 print "open successful, fh is $_[0]\n";
257 ... 363 ...
258 } else { 364 } else {
259 die "open failed: $!\n"; 365 die "open failed: $!\n";
260 } 366 }
261 }; 367 };
262 368
369 In addition to all the common open modes/flags ("O_RDONLY",
370 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
371 "O_APPEND"), the following POSIX and non-POSIX constants are
372 available (missing ones on your system are, as usual, 0):
373
374 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
375 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
376 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
377 and "O_ACCMODE".
378
263 aio_close $fh, $callback->($status) 379 aio_close $fh, $callback->($status)
264 Asynchronously close a file and call the callback with the result 380 Asynchronously close a file and call the callback with the result
265 code. 381 code.
266 382
267 Unfortunately, you can't do this to perl. Perl *insists* very 383 Unfortunately, you can't do this to perl. Perl *insists* very
… …
272 will use dup2 to overwrite the file descriptor with the write-end of 388 will use dup2 to overwrite the file descriptor with the write-end of
273 a pipe (the pipe fd will be created on demand and will be cached). 389 a pipe (the pipe fd will be created on demand and will be cached).
274 390
275 Or in other words: the file descriptor will be closed, but it will 391 Or in other words: the file descriptor will be closed, but it will
276 not be free for reuse until the perl filehandle is closed. 392 not be free for reuse until the perl filehandle is closed.
393
394 aio_seek $fh, $offset, $whence, $callback->($offs)
395 Seeks the filehandle to the new $offset, similarly to perl's
396 "sysseek". The $whence can use the traditional values (0 for
397 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
398 "IO::AIO::SEEK_END").
399
400 The resulting absolute offset will be passed to the callback, or -1
401 in case of an error.
402
403 In theory, the $whence constants could be different than the
404 corresponding values from Fcntl, but perl guarantees they are the
405 same, so don't panic.
406
407 As a GNU/Linux (and maybe Solaris) extension, also the constants
408 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
409 could be found. No guarantees about suitability for use in
410 "aio_seek" or Perl's "sysseek" can be made though, although I would
411 naively assume they "just work".
277 412
278 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 413 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 414 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280 Reads or writes $length bytes from or to the specified $fh and 415 Reads or writes $length bytes from or to the specified $fh and
281 $offset into the scalar given by $data and offset $dataoffset and 416 $offset into the scalar given by $data and offset $dataoffset and
282 calls the callback without the actual number of bytes read (or -1 on 417 calls the callback with the actual number of bytes transferred (or
283 error, just like the syscall). 418 -1 on error, just like the syscall).
284 419
285 "aio_read" will, like "sysread", shrink or grow the $data scalar to 420 "aio_read" will, like "sysread", shrink or grow the $data scalar to
286 offset plus the actual number of bytes read. 421 offset plus the actual number of bytes read.
287 422
288 If $offset is undefined, then the current file descriptor offset 423 If $offset is undefined, then the current file descriptor offset
… …
310 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 445 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
311 Tries to copy $length bytes from $in_fh to $out_fh. It starts 446 Tries to copy $length bytes from $in_fh to $out_fh. It starts
312 reading at byte offset $in_offset, and starts writing at the current 447 reading at byte offset $in_offset, and starts writing at the current
313 file offset of $out_fh. Because of that, it is not safe to issue 448 file offset of $out_fh. Because of that, it is not safe to issue
314 more than one "aio_sendfile" per $out_fh, as they will interfere 449 more than one "aio_sendfile" per $out_fh, as they will interfere
315 with each other. 450 with each other. The same $in_fh works fine though, as this function
451 does not move or use the file offset of $in_fh.
316 452
453 Please note that "aio_sendfile" can read more bytes from $in_fh than
454 are written, and there is no way to find out how many more bytes
455 have been read from "aio_sendfile" alone, as "aio_sendfile" only
456 provides the number of bytes written to $out_fh. Only if the result
457 value equals $length one can assume that $length bytes have been
458 read.
459
460 Unlike with other "aio_" functions, it makes a lot of sense to use
461 "aio_sendfile" on non-blocking sockets, as long as one end
462 (typically the $in_fh) is a file - the file I/O will then be
463 asynchronous, while the socket I/O will be non-blocking. Note,
464 however, that you can run into a trap where "aio_sendfile" reads
465 some data with readahead, then fails to write all data, and when the
466 socket is ready the next time, the data in the cache is already
467 lost, forcing "aio_sendfile" to again hit the disk. Explicit
468 "aio_read" + "aio_write" let's you better control resource usage.
469
317 This call tries to make use of a native "sendfile" syscall to 470 This call tries to make use of a native "sendfile"-like syscall to
318 provide zero-copy operation. For this to work, $out_fh should refer 471 provide zero-copy operation. For this to work, $out_fh should refer
319 to a socket, and $in_fh should refer to mmap'able file. 472 to a socket, and $in_fh should refer to an mmap'able file.
320 473
321 If the native sendfile call fails or is not implemented, it will be 474 If a native sendfile cannot be found or it fails with "ENOSYS",
322 emulated, so you can call "aio_sendfile" on any type of filehandle 475 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
323 regardless of the limitations of the operating system. 476 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
477 any type of filehandle regardless of the limitations of the
478 operating system.
324 479
325 Please note, however, that "aio_sendfile" can read more bytes from 480 As native sendfile syscalls (as practically any non-POSIX interface
326 $in_fh than are written, and there is no way to find out how many 481 hacked together in a hurry to improve benchmark numbers) tend to be
327 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 482 rather buggy on many systems, this implementation tries to work
328 only provides the number of bytes written to $out_fh. Only if the 483 around some known bugs in Linux and FreeBSD kernels (probably
329 result value equals $length one can assume that $length bytes have 484 others, too), but that might fail, so you really really should check
330 been read. 485 the return value of "aio_sendfile" - fewer bytes than expected might
486 have been transferred.
331 487
332 aio_readahead $fh,$offset,$length, $callback->($retval) 488 aio_readahead $fh,$offset,$length, $callback->($retval)
333 "aio_readahead" populates the page cache with data from a file so 489 "aio_readahead" populates the page cache with data from a file so
334 that subsequent reads from that file will not block on disk I/O. The 490 that subsequent reads from that file will not block on disk I/O. The
335 $offset argument specifies the starting point from which data is to 491 $offset argument specifies the starting point from which data is to
… …
338 to a page boundary and bytes are read up to the next page boundary 494 to a page boundary and bytes are read up to the next page boundary
339 greater than or equal to (off-set+length). "aio_readahead" does not 495 greater than or equal to (off-set+length). "aio_readahead" does not
340 read beyond the end of the file. The current file offset of the file 496 read beyond the end of the file. The current file offset of the file
341 is left unchanged. 497 is left unchanged.
342 498
343 If that syscall doesn't exist (likely if your OS isn't Linux) it 499 If that syscall doesn't exist (likely if your kernel isn't Linux) it
344 will be emulated by simply reading the data, which would have a 500 will be emulated by simply reading the data, which would have a
345 similar effect. 501 similar effect.
346 502
347 aio_stat $fh_or_path, $callback->($status) 503 aio_stat $fh_or_path, $callback->($status)
348 aio_lstat $fh, $callback->($status) 504 aio_lstat $fh, $callback->($status)
349 Works like perl's "stat" or "lstat" in void context. The callback 505 Works almost exactly like perl's "stat" or "lstat" in void context.
350 will be called after the stat and the results will be available 506 The callback will be called after the stat and the results will be
351 using "stat _" or "-s _" etc... 507 available using "stat _" or "-s _" and other tests (with the
352 508 exception of "-B" and "-T").
353 The pathname passed to "aio_stat" must be absolute. See API NOTES,
354 above, for an explanation.
355 509
356 Currently, the stats are always 64-bit-stats, i.e. instead of 510 Currently, the stats are always 64-bit-stats, i.e. instead of
357 returning an error when stat'ing a large file, the results will be 511 returning an error when stat'ing a large file, the results will be
358 silently truncated unless perl itself is compiled with large file 512 silently truncated unless perl itself is compiled with large file
359 support. 513 support.
360 514
515 To help interpret the mode and dev/rdev stat values, IO::AIO offers
516 the following constants and functions (if not implemented, the
517 constants will be 0 and the functions will either "croak" or fall
518 back on traditional behaviour).
519
520 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
521 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
522 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
523
524 To access higher resolution stat timestamps, see "SUBSECOND STAT
525 TIME ACCESS".
526
361 Example: Print the length of /etc/passwd: 527 Example: Print the length of /etc/passwd:
362 528
363 aio_stat "/etc/passwd", sub { 529 aio_stat "/etc/passwd", sub {
364 $_[0] and die "stat failed: $!"; 530 $_[0] and die "stat failed: $!";
365 print "size is ", -s _, "\n"; 531 print "size is ", -s _, "\n";
366 }; 532 };
367 533
534 aio_statvfs $fh_or_path, $callback->($statvfs)
535 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
536 whether a file handle or path was passed.
537
538 On success, the callback is passed a hash reference with the
539 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
540 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
541 failure, "undef" is passed.
542
543 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
544 and "ST_NOSUID".
545
546 The following non-POSIX IO::AIO::ST_* flag masks are defined to
547 their correct value when available, or to 0 on systems that do not
548 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
549 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
550 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
551
552 Example: stat "/wd" and dump out the data if successful.
553
554 aio_statvfs "/wd", sub {
555 my $f = $_[0]
556 or die "statvfs: $!";
557
558 use Data::Dumper;
559 say Dumper $f;
560 };
561
562 # result:
563 {
564 bsize => 1024,
565 bfree => 4333064312,
566 blocks => 10253828096,
567 files => 2050765568,
568 flag => 4096,
569 favail => 2042092649,
570 bavail => 4333064312,
571 ffree => 2042092649,
572 namemax => 255,
573 frsize => 1024,
574 fsid => 1810
575 }
576
368 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 577 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
369 Works like perl's "utime" function (including the special case of 578 Works like perl's "utime" function (including the special case of
370 $atime and $mtime being undef). Fractional times are supported if 579 $atime and $mtime being undef). Fractional times are supported if
371 the underlying syscalls support them. 580 the underlying syscalls support them.
372 581
373 When called with a pathname, uses utimes(2) if available, otherwise 582 When called with a pathname, uses utimensat(2) or utimes(2) if
374 utime(2). If called on a file descriptor, uses futimes(2) if 583 available, otherwise utime(2). If called on a file descriptor, uses
375 available, otherwise returns ENOSYS, so this is not portable. 584 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
585 this is not portable.
376 586
377 Examples: 587 Examples:
378 588
379 # set atime and mtime to current time (basically touch(1)): 589 # set atime and mtime to current time (basically touch(1)):
380 aio_utime "path", undef, undef; 590 aio_utime "path", undef, undef;
… …
394 aio_chown "path", 0, undef; 604 aio_chown "path", 0, undef;
395 605
396 aio_truncate $fh_or_path, $offset, $callback->($status) 606 aio_truncate $fh_or_path, $offset, $callback->($status)
397 Works like truncate(2) or ftruncate(2). 607 Works like truncate(2) or ftruncate(2).
398 608
609 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
610 Allocates or frees disk space according to the $mode argument. See
611 the linux "fallocate" documentation for details.
612
613 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
614 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
615 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
616
617 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
618 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
619 "FALLOC_FL_INSERT_RANGE" to insert a range and
620 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
621 fallocate(2) manpage).
622
623 The file system block size used by "fallocate" is presumably the
624 "f_bsize" returned by "statvfs", but different filesystems and
625 filetypes can dictate other limitations.
626
627 If "fallocate" isn't available or cannot be emulated (currently no
628 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
629
399 aio_chmod $fh_or_path, $mode, $callback->($status) 630 aio_chmod $fh_or_path, $mode, $callback->($status)
400 Works like perl's "chmod" function. 631 Works like perl's "chmod" function.
401 632
402 aio_unlink $pathname, $callback->($status) 633 aio_unlink $pathname, $callback->($status)
403 Asynchronously unlink (delete) a file and call the callback with the 634 Asynchronously unlink (delete) a file and call the callback with the
404 result code. 635 result code.
405 636
406 aio_mknod $path, $mode, $dev, $callback->($status) 637 aio_mknod $pathname, $mode, $dev, $callback->($status)
407 [EXPERIMENTAL] 638 [EXPERIMENTAL]
408 639
409 Asynchronously create a device node (or fifo). See mknod(2). 640 Asynchronously create a device node (or fifo). See mknod(2).
410 641
411 The only (POSIX-) portable way of calling this function is: 642 The only (POSIX-) portable way of calling this function is:
412 643
413 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 644 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
645
646 See "aio_stat" for info about some potentially helpful extra
647 constants and functions.
414 648
415 aio_link $srcpath, $dstpath, $callback->($status) 649 aio_link $srcpath, $dstpath, $callback->($status)
416 Asynchronously create a new link to the existing object at $srcpath 650 Asynchronously create a new link to the existing object at $srcpath
417 at the path $dstpath and call the callback with the result code. 651 at the path $dstpath and call the callback with the result code.
418 652
419 aio_symlink $srcpath, $dstpath, $callback->($status) 653 aio_symlink $srcpath, $dstpath, $callback->($status)
420 Asynchronously create a new symbolic link to the existing object at 654 Asynchronously create a new symbolic link to the existing object at
421 $srcpath at the path $dstpath and call the callback with the result 655 $srcpath at the path $dstpath and call the callback with the result
422 code. 656 code.
423 657
424 aio_readlink $path, $callback->($link) 658 aio_readlink $pathname, $callback->($link)
425 Asynchronously read the symlink specified by $path and pass it to 659 Asynchronously read the symlink specified by $path and pass it to
426 the callback. If an error occurs, nothing or undef gets passed to 660 the callback. If an error occurs, nothing or undef gets passed to
427 the callback. 661 the callback.
428 662
663 aio_realpath $pathname, $callback->($path)
664 Asynchronously make the path absolute and resolve any symlinks in
665 $path. The resulting path only consists of directories (same as
666 Cwd::realpath).
667
668 This request can be used to get the absolute path of the current
669 working directory by passing it a path of . (a single dot).
670
429 aio_rename $srcpath, $dstpath, $callback->($status) 671 aio_rename $srcpath, $dstpath, $callback->($status)
430 Asynchronously rename the object at $srcpath to $dstpath, just as 672 Asynchronously rename the object at $srcpath to $dstpath, just as
431 rename(2) and call the callback with the result code. 673 rename(2) and call the callback with the result code.
674
675 On systems that support the AIO::WD working directory abstraction
676 natively, the case "[$wd, "."]" as $srcpath is specialcased -
677 instead of failing, "rename" is called on the absolute path of $wd.
678
679 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
680 Basically a version of "aio_rename" with an additional $flags
681 argument. Calling this with "$flags=0" is the same as calling
682 "aio_rename".
683
684 Non-zero flags are currently only supported on GNU/Linux systems
685 that support renameat2. Other systems fail with "ENOSYS" in this
686 case.
687
688 The following constants are available (missing ones are, as usual
689 0), see renameat2(2) for details:
690
691 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
692 "IO::AIO::RENAME_WHITEOUT".
432 693
433 aio_mkdir $pathname, $mode, $callback->($status) 694 aio_mkdir $pathname, $mode, $callback->($status)
434 Asynchronously mkdir (create) a directory and call the callback with 695 Asynchronously mkdir (create) a directory and call the callback with
435 the result code. $mode will be modified by the umask at the time the 696 the result code. $mode will be modified by the umask at the time the
436 request is executed, so do not change your umask. 697 request is executed, so do not change your umask.
437 698
438 aio_rmdir $pathname, $callback->($status) 699 aio_rmdir $pathname, $callback->($status)
439 Asynchronously rmdir (delete) a directory and call the callback with 700 Asynchronously rmdir (delete) a directory and call the callback with
440 the result code. 701 the result code.
441 702
703 On systems that support the AIO::WD working directory abstraction
704 natively, the case "[$wd, "."]" is specialcased - instead of
705 failing, "rmdir" is called on the absolute path of $wd.
706
442 aio_readdir $pathname, $callback->($entries) 707 aio_readdir $pathname, $callback->($entries)
443 Unlike the POSIX call of the same name, "aio_readdir" reads an 708 Unlike the POSIX call of the same name, "aio_readdir" reads an
444 entire directory (i.e. opendir + readdir + closedir). The entries 709 entire directory (i.e. opendir + readdir + closedir). The entries
445 will not be sorted, and will NOT include the "." and ".." entries. 710 will not be sorted, and will NOT include the "." and ".." entries.
446 711
447 The callback is passed a single argument which is either "undef" or 712 The callback is passed a single argument which is either "undef" or
448 an array-ref with the filenames. 713 an array-ref with the filenames.
449 714
450 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 715 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
451 Quite similar to "aio_readdir", but the $flags argument allows to 716 Quite similar to "aio_readdir", but the $flags argument allows one
452 tune behaviour and output format. In case of an error, $entries will 717 to tune behaviour and output format. In case of an error, $entries
453 be "undef". 718 will be "undef".
454 719
455 The flags are a combination of the following constants, ORed 720 The flags are a combination of the following constants, ORed
456 together (the flags will also be passed to the callback, possibly 721 together (the flags will also be passed to the callback, possibly
457 modified): 722 modified):
458 723
459 IO::AIO::READDIR_DENTS 724 IO::AIO::READDIR_DENTS
460 When this flag is off, then the callback gets an arrayref with 725 Normally the callback gets an arrayref consisting of names only
461 of names only (as with "aio_readdir"), otherwise it gets an 726 (as with "aio_readdir"). If this flag is set, then the callback
462 arrayref with "[$name, $type, $inode]" arrayrefs, each 727 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
463 describing a single directory entry in more detail. 728 describing a single directory entry in more detail:
464 729
465 $name is the name of the entry. 730 $name is the name of the entry.
466 731
467 $type is one of the "IO::AIO::DT_xxx" constants: 732 $type is one of the "IO::AIO::DT_xxx" constants:
468 733
469 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 734 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
470 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 735 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
471 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 736 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
472 737
473 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 738 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
474 you need to know, you have to run stat yourself. Also, for speed 739 you need to know, you have to run stat yourself. Also, for
475 reasons, the $type scalars are read-only: you can not modify 740 speed/memory reasons, the $type scalars are read-only: you must
476 them. 741 not modify them.
477 742
478 $inode is the inode number (which might not be exact on systems 743 $inode is the inode number (which might not be exact on systems
479 with 64 bit inode numbers and 32 bit perls). On systems that do 744 with 64 bit inode numbers and 32 bit perls). This field has
480 not deliver the inode information, this will always be zero. 745 unspecified content on systems that do not deliver the inode
746 information.
481 747
482 IO::AIO::READDIR_DIRS_FIRST 748 IO::AIO::READDIR_DIRS_FIRST
483 When this flag is set, then the names will be returned in an 749 When this flag is set, then the names will be returned in an
484 order where likely directories come first. This is useful when 750 order where likely directories come first, in optimal stat
485 you need to quickly find directories, or you want to find all 751 order. This is useful when you need to quickly find directories,
486 directories while avoiding to stat() each entry. 752 or you want to find all directories while avoiding to stat()
753 each entry.
487 754
488 If the system returns type information in readdir, then this is 755 If the system returns type information in readdir, then this is
489 used to find directories directly. Otherwise, likely directories 756 used to find directories directly. Otherwise, likely directories
490 are files beginning with ".", or otherwise files with no dots, 757 are names beginning with ".", or otherwise names with no dots,
491 of which files with short names are tried first. 758 of which names with short names are tried first.
492 759
493 IO::AIO::READDIR_STAT_ORDER 760 IO::AIO::READDIR_STAT_ORDER
494 When this flag is set, then the names will be returned in an 761 When this flag is set, then the names will be returned in an
495 order suitable for stat()'ing each one. That is, when you plan 762 order suitable for stat()'ing each one. That is, when you plan
496 to stat() all files in the given directory, then the returned 763 to stat() most or all files in the given directory, then the
497 order will likely be fastest. 764 returned order will likely be faster.
498 765
499 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 766 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
500 specified, then the likely dirs come first, resulting in a less 767 specified, then the likely dirs come first, resulting in a less
501 optimal stat order. 768 optimal stat order for stat'ing all entries, but likely a more
769 optimal order for finding subdirectories.
502 770
503 IO::AIO::READDIR_FOUND_UNKNOWN 771 IO::AIO::READDIR_FOUND_UNKNOWN
504 This flag should not be set when calling "aio_readdirx". 772 This flag should not be set when calling "aio_readdirx".
505 Instead, it is being set by "aio_readdirx", when any of the 773 Instead, it is being set by "aio_readdirx", when any of the
506 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 774 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
507 flag therefore indicates that all $type's are known, which can 775 flag therefore indicates that all $type's are known, which can
508 be used to speed up some algorithms. 776 be used to speed up some algorithms.
509 777
778 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
779 Opens, reads and closes the given file. The data is put into $data,
780 which is resized as required.
781
782 If $offset is negative, then it is counted from the end of the file.
783
784 If $length is zero, then the remaining length of the file is used.
785 Also, in this case, the same limitations to modifying $data apply as
786 when IO::AIO::mmap is used, i.e. it must only be modified in-place
787 with "substr". If the size of the file is known, specifying a
788 non-zero $length results in a performance advantage.
789
790 This request is similar to the older "aio_load" request, but since
791 it is a single request, it might be more efficient to use.
792
793 Example: load /etc/passwd into $passwd.
794
795 my $passwd;
796 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
797 $_[0] >= 0
798 or die "/etc/passwd: $!\n";
799
800 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
801 print $passwd;
802 };
803 IO::AIO::flush;
804
510 aio_load $path, $data, $callback->($status) 805 aio_load $pathname, $data, $callback->($status)
511 This is a composite request that tries to fully load the given file 806 This is a composite request that tries to fully load the given file
512 into memory. Status is the same as with aio_read. 807 into memory. Status is the same as with aio_read.
808
809 Using "aio_slurp" might be more efficient, as it is a single
810 request.
513 811
514 aio_copy $srcpath, $dstpath, $callback->($status) 812 aio_copy $srcpath, $dstpath, $callback->($status)
515 Try to copy the *file* (directories not supported as either source 813 Try to copy the *file* (directories not supported as either source
516 or destination) from $srcpath to $dstpath and call the callback with 814 or destination) from $srcpath to $dstpath and call the callback with
517 the 0 (error) or -1 ok. 815 a status of 0 (ok) or -1 (error, see $!).
816
817 Existing destination files will be truncated.
518 818
519 This is a composite request that creates the destination file with 819 This is a composite request that creates the destination file with
520 mode 0200 and copies the contents of the source file into it using 820 mode 0200 and copies the contents of the source file into it using
521 "aio_sendfile", followed by restoring atime, mtime, access mode and 821 "aio_sendfile", followed by restoring atime, mtime, access mode and
522 uid/gid, in that order. 822 uid/gid, in that order.
… …
526 uid/gid, where errors are being ignored. 826 uid/gid, where errors are being ignored.
527 827
528 aio_move $srcpath, $dstpath, $callback->($status) 828 aio_move $srcpath, $dstpath, $callback->($status)
529 Try to move the *file* (directories not supported as either source 829 Try to move the *file* (directories not supported as either source
530 or destination) from $srcpath to $dstpath and call the callback with 830 or destination) from $srcpath to $dstpath and call the callback with
531 the 0 (error) or -1 ok. 831 a status of 0 (ok) or -1 (error, see $!).
532 832
533 This is a composite request that tries to rename(2) the file first; 833 This is a composite request that tries to rename(2) the file first;
534 if rename fails with "EXDEV", it copies the file with "aio_copy" 834 if rename fails with "EXDEV", it copies the file with "aio_copy"
535 and, if that is successful, unlinks the $srcpath. 835 and, if that is successful, unlinks the $srcpath.
536 836
537 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 837 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
538 Scans a directory (similar to "aio_readdir") but additionally tries 838 Scans a directory (similar to "aio_readdir") but additionally tries
539 to efficiently separate the entries of directory $path into two sets 839 to efficiently separate the entries of directory $path into two sets
540 of names, directories you can recurse into (directories), and ones 840 of names, directories you can recurse into (directories), and ones
541 you cannot recurse into (everything else, including symlinks to 841 you cannot recurse into (everything else, including symlinks to
542 directories). 842 directories).
543 843
544 "aio_scandir" is a composite request that creates of many sub 844 "aio_scandir" is a composite request that generates many sub
545 requests_ $maxreq specifies the maximum number of outstanding aio 845 requests. $maxreq specifies the maximum number of outstanding aio
546 requests that this function generates. If it is "<= 0", then a 846 requests that this function generates. If it is "<= 0", then a
547 suitable default will be chosen (currently 4). 847 suitable default will be chosen (currently 4).
548 848
549 On error, the callback is called without arguments, otherwise it 849 On error, the callback is called without arguments, otherwise it
550 receives two array-refs with path-relative entry names. 850 receives two array-refs with path-relative entry names.
… …
575 Then entries will be sorted into likely directories a non-initial 875 Then entries will be sorted into likely directories a non-initial
576 dot currently) and likely non-directories (see "aio_readdirx"). Then 876 dot currently) and likely non-directories (see "aio_readdirx"). Then
577 every entry plus an appended "/." will be "stat"'ed, likely 877 every entry plus an appended "/." will be "stat"'ed, likely
578 directories first, in order of their inode numbers. If that 878 directories first, in order of their inode numbers. If that
579 succeeds, it assumes that the entry is a directory or a symlink to 879 succeeds, it assumes that the entry is a directory or a symlink to
580 directory (which will be checked seperately). This is often faster 880 directory (which will be checked separately). This is often faster
581 than stat'ing the entry itself because filesystems might detect the 881 than stat'ing the entry itself because filesystems might detect the
582 type of the entry without reading the inode data (e.g. ext2fs 882 type of the entry without reading the inode data (e.g. ext2fs
583 filetype feature), even on systems that cannot return the filetype 883 filetype feature), even on systems that cannot return the filetype
584 information on readdir. 884 information on readdir.
585 885
… …
591 891
592 It will also likely work on non-POSIX filesystems with reduced 892 It will also likely work on non-POSIX filesystems with reduced
593 efficiency as those tend to return 0 or 1 as link counts, which 893 efficiency as those tend to return 0 or 1 as link counts, which
594 disables the directory counting heuristic. 894 disables the directory counting heuristic.
595 895
596 aio_rmtree $path, $callback->($status) 896 aio_rmtree $pathname, $callback->($status)
597 Delete a directory tree starting (and including) $path, return the 897 Delete a directory tree starting (and including) $path, return the
598 status of the final "rmdir" only. This is a composite request that 898 status of the final "rmdir" only. This is a composite request that
599 uses "aio_scandir" to recurse into and rmdir directories, and unlink 899 uses "aio_scandir" to recurse into and rmdir directories, and unlink
600 everything else. 900 everything else.
601 901
902 aio_fcntl $fh, $cmd, $arg, $callback->($status)
903 aio_ioctl $fh, $request, $buf, $callback->($status)
904 These work just like the "fcntl" and "ioctl" built-in functions,
905 except they execute asynchronously and pass the return value to the
906 callback.
907
908 Both calls can be used for a lot of things, some of which make more
909 sense to run asynchronously in their own thread, while some others
910 make less sense. For example, calls that block waiting for external
911 events, such as locking, will also lock down an I/O thread while it
912 is waiting, which can deadlock the whole I/O system. At the same
913 time, there might be no alternative to using a thread to wait.
914
915 So in general, you should only use these calls for things that do
916 (filesystem) I/O, not for things that wait for other events
917 (network, other processes), although if you are careful and know
918 what you are doing, you still can.
919
920 The following constants are available and can be used for normal
921 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
922
923 "F_DUPFD_CLOEXEC",
924
925 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
926
927 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
928 "FIDEDUPERANGE".
929
930 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
931 "F_SEAL_GROW" and "F_SEAL_WRITE".
932
933 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
934 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
935
936 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
937 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
938 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
939
940 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
941 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
942 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
943 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
944 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
945
946 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
947 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
948 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
949 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
950 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
951 "FS_XFLAG_HASATTR",
952
953 "BLKROSET", "BLKROGET", "BLKRRPART", "BLKGETSIZE", "BLKFLSBUF",
954 "BLKRASET", "BLKRAGET", "BLKFRASET", "BLKFRAGET", "BLKSECTSET",
955 "BLKSECTGET", "BLKSSZGET", "BLKBSZGET", "BLKBSZSET", "BLKGETSIZE64",
956
602 aio_sync $callback->($status) 957 aio_sync $callback->($status)
603 Asynchronously call sync and call the callback when finished. 958 Asynchronously call sync and call the callback when finished.
604 959
605 aio_fsync $fh, $callback->($status) 960 aio_fsync $fh, $callback->($status)
606 Asynchronously call fsync on the given filehandle and call the 961 Asynchronously call fsync on the given filehandle and call the
… …
610 Asynchronously call fdatasync on the given filehandle and call the 965 Asynchronously call fdatasync on the given filehandle and call the
611 callback with the fdatasync result code. 966 callback with the fdatasync result code.
612 967
613 If this call isn't available because your OS lacks it or it couldn't 968 If this call isn't available because your OS lacks it or it couldn't
614 be detected, it will be emulated by calling "fsync" instead. 969 be detected, it will be emulated by calling "fsync" instead.
970
971 aio_syncfs $fh, $callback->($status)
972 Asynchronously call the syncfs syscall to sync the filesystem
973 associated to the given filehandle and call the callback with the
974 syncfs result code. If syncfs is not available, calls sync(), but
975 returns -1 and sets errno to "ENOSYS" nevertheless.
615 976
616 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 977 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
617 Sync the data portion of the file specified by $offset and $length 978 Sync the data portion of the file specified by $offset and $length
618 to disk (but NOT the metadata), by calling the Linux-specific 979 to disk (but NOT the metadata), by calling the Linux-specific
619 sync_file_range call. If sync_file_range is not available or it 980 sync_file_range call. If sync_file_range is not available or it
… …
623 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 984 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
624 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 985 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
625 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 986 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
626 manpage for details. 987 manpage for details.
627 988
628 aio_pathsync $path, $callback->($status) 989 aio_pathsync $pathname, $callback->($status)
629 This request tries to open, fsync and close the given path. This is 990 This request tries to open, fsync and close the given path. This is
630 a composite request intended to sync directories after directory 991 a composite request intended to sync directories after directory
631 operations (E.g. rename). This might not work on all operating 992 operations (E.g. rename). This might not work on all operating
632 systems or have any specific effect, but usually it makes sure that 993 systems or have any specific effect, but usually it makes sure that
633 directory changes get written to disc. It works for anything that 994 directory changes get written to disc. It works for anything that
634 can be opened for read-only, not just directories. 995 can be opened for read-only, not just directories.
635 996
997 Future versions of this function might fall back to other methods
998 when "fsync" on the directory fails (such as calling "sync").
999
636 Passes 0 when everything went ok, and -1 on error. 1000 Passes 0 when everything went ok, and -1 on error.
1001
1002 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
1003 $callback->($status)
1004 This is a rather advanced IO::AIO call, which only works on
1005 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
1006 also works on data scalars managed by the Sys::Mmap or Mmap modules,
1007 note that the scalar must only be modified in-place while an aio
1008 operation is pending on it).
1009
1010 It calls the "msync" function of your OS, if available, with the
1011 memory area starting at $offset in the string and ending $length
1012 bytes later. If $length is negative, counts from the end, and if
1013 $length is "undef", then it goes till the end of the string. The
1014 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
1015 an optional "IO::AIO::MS_INVALIDATE".
1016
1017 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
1018 $callback->($status)
1019 This is a rather advanced IO::AIO call, which works best on
1020 mmap(2)ed scalars.
1021
1022 It touches (reads or writes) all memory pages in the specified range
1023 inside the scalar. All caveats and parameters are the same as for
1024 "aio_msync", above, except for flags, which must be either 0 (which
1025 reads all pages and ensures they are instantiated) or
1026 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
1027 and writing an octet from it, which dirties the page).
1028
1029 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1030 This is a rather advanced IO::AIO call, which works best on
1031 mmap(2)ed scalars.
1032
1033 It reads in all the pages of the underlying storage into memory (if
1034 any) and locks them, so they are not getting swapped/paged out or
1035 removed.
1036
1037 If $length is undefined, then the scalar will be locked till the
1038 end.
1039
1040 On systems that do not implement "mlock", this function returns -1
1041 and sets errno to "ENOSYS".
1042
1043 Note that the corresponding "munlock" is synchronous and is
1044 documented under "MISCELLANEOUS FUNCTIONS".
1045
1046 Example: open a file, mmap and mlock it - both will be undone when
1047 $data gets destroyed.
1048
1049 open my $fh, "<", $path or die "$path: $!";
1050 my $data;
1051 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1052 aio_mlock $data; # mlock in background
1053
1054 aio_mlockall $flags, $callback->($status)
1055 Calls the "mlockall" function with the given $flags (a combination
1056 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1057 "IO::AIO::MCL_ONFAULT").
1058
1059 On systems that do not implement "mlockall", this function returns
1060 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1061 supported by the system result in a return value of -1 with errno
1062 being set to "EINVAL".
1063
1064 Note that the corresponding "munlockall" is synchronous and is
1065 documented under "MISCELLANEOUS FUNCTIONS".
1066
1067 Example: asynchronously lock all current and future pages into
1068 memory.
1069
1070 aio_mlockall IO::AIO::MCL_FUTURE;
1071
1072 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1073 Queries the extents of the given file (by calling the Linux "FIEMAP"
1074 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1075 details). If the ioctl is not available on your OS, then this
1076 request will fail with "ENOSYS".
1077
1078 $start is the starting offset to query extents for, $length is the
1079 size of the range to query - if it is "undef", then the whole file
1080 will be queried.
1081
1082 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1083 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1084 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1085 query the data portion.
1086
1087 $count is the maximum number of extent records to return. If it is
1088 "undef", then IO::AIO queries all extents of the range. As a very
1089 special case, if it is 0, then the callback receives the number of
1090 extents instead of the extents themselves (which is unreliable, see
1091 below).
1092
1093 If an error occurs, the callback receives no arguments. The special
1094 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1095
1096 Otherwise, the callback receives an array reference with extent
1097 structures. Each extent structure is an array reference itself, with
1098 the following members:
1099
1100 [$logical, $physical, $length, $flags]
1101
1102 Flags is any combination of the following flag values (typically
1103 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1104
1105 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1106 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1107 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1108 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1109 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1110 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1111 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1112 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1113
1114 At the time of this writing (Linux 3.2), this request is unreliable
1115 unless $count is "undef", as the kernel has all sorts of bugs
1116 preventing it to return all extents of a range for files with a
1117 large number of extents. The code (only) works around all these
1118 issues if $count is "undef".
637 1119
638 aio_group $callback->(...) 1120 aio_group $callback->(...)
639 This is a very special aio request: Instead of doing something, it 1121 This is a very special aio request: Instead of doing something, it
640 is a container for other aio requests, which is useful if you want 1122 is a container for other aio requests, which is useful if you want
641 to bundle many requests into a single, composite, request with a 1123 to bundle many requests into a single, composite, request with a
… …
676 requests like sleep and file handle readable/writable, the overhead 1158 requests like sleep and file handle readable/writable, the overhead
677 this creates is immense (it blocks a thread for a long time) so do 1159 this creates is immense (it blocks a thread for a long time) so do
678 not use this function except to put your application under 1160 not use this function except to put your application under
679 artificial I/O pressure. 1161 artificial I/O pressure.
680 1162
1163 IO::AIO::WD - multiple working directories
1164 Your process only has one current working directory, which is used by
1165 all threads. This makes it hard to use relative paths (some other
1166 component could call "chdir" at any time, and it is hard to control when
1167 the path will be used by IO::AIO).
1168
1169 One solution for this is to always use absolute paths. This usually
1170 works, but can be quite slow (the kernel has to walk the whole path on
1171 every access), and can also be a hassle to implement.
1172
1173 Newer POSIX systems have a number of functions (openat, fdopendir,
1174 futimensat and so on) that make it possible to specify working
1175 directories per operation.
1176
1177 For portability, and because the clowns who "designed", or shall I
1178 write, perpetrated this new interface were obviously half-drunk, this
1179 abstraction cannot be perfect, though.
1180
1181 IO::AIO allows you to convert directory paths into a so-called
1182 IO::AIO::WD object. This object stores the canonicalised, absolute
1183 version of the path, and on systems that allow it, also a directory file
1184 descriptor.
1185
1186 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1187 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1188 object and a pathname instead (or the IO::AIO::WD object alone, which
1189 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1190 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1191 relative to that IO::AIO::WD object.
1192
1193 For example, to get a wd object for /etc and then stat passwd inside,
1194 you would write:
1195
1196 aio_wd "/etc", sub {
1197 my $etcdir = shift;
1198
1199 # although $etcdir can be undef on error, there is generally no reason
1200 # to check for errors here, as aio_stat will fail with ENOENT
1201 # when $etcdir is undef.
1202
1203 aio_stat [$etcdir, "passwd"], sub {
1204 # yay
1205 };
1206 };
1207
1208 The fact that "aio_wd" is a request and not a normal function shows that
1209 creating an IO::AIO::WD object is itself a potentially blocking
1210 operation, which is why it is done asynchronously.
1211
1212 To stat the directory obtained with "aio_wd" above, one could write
1213 either of the following three request calls:
1214
1215 aio_lstat "/etc" , sub { ... # pathname as normal string
1216 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1217 aio_lstat $wd , sub { ... # shorthand for the previous
1218
1219 As with normal pathnames, IO::AIO keeps a copy of the working directory
1220 object and the pathname string, so you could write the following without
1221 causing any issues due to $path getting reused:
1222
1223 my $path = [$wd, undef];
1224
1225 for my $name (qw(abc def ghi)) {
1226 $path->[1] = $name;
1227 aio_stat $path, sub {
1228 # ...
1229 };
1230 }
1231
1232 There are some caveats: when directories get renamed (or deleted), the
1233 pathname string doesn't change, so will point to the new directory (or
1234 nowhere at all), while the directory fd, if available on the system,
1235 will still point to the original directory. Most functions accepting a
1236 pathname will use the directory fd on newer systems, and the string on
1237 older systems. Some functions (such as "aio_realpath") will always rely
1238 on the string form of the pathname.
1239
1240 So this functionality is mainly useful to get some protection against
1241 "chdir", to easily get an absolute path out of a relative path for
1242 future reference, and to speed up doing many operations in the same
1243 directory (e.g. when stat'ing all files in a directory).
1244
1245 The following functions implement this working directory abstraction:
1246
1247 aio_wd $pathname, $callback->($wd)
1248 Asynchonously canonicalise the given pathname and convert it to an
1249 IO::AIO::WD object representing it. If possible and supported on the
1250 system, also open a directory fd to speed up pathname resolution
1251 relative to this working directory.
1252
1253 If something goes wrong, then "undef" is passwd to the callback
1254 instead of a working directory object and $! is set appropriately.
1255 Since passing "undef" as working directory component of a pathname
1256 fails the request with "ENOENT", there is often no need for error
1257 checking in the "aio_wd" callback, as future requests using the
1258 value will fail in the expected way.
1259
1260 IO::AIO::CWD
1261 This is a compile time constant (object) that represents the process
1262 current working directory.
1263
1264 Specifying this object as working directory object for a pathname is
1265 as if the pathname would be specified directly, without a directory
1266 object. For example, these calls are functionally identical:
1267
1268 aio_stat "somefile", sub { ... };
1269 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1270
1271 To recover the path associated with an IO::AIO::WD object, you can use
1272 "aio_realpath":
1273
1274 aio_realpath $wd, sub {
1275 warn "path is $_[0]\n";
1276 };
1277
1278 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1279 sometimes, fall back to using an absolue path.
1280
681 IO::AIO::REQ CLASS 1281 IO::AIO::REQ CLASS
682 All non-aggregate "aio_*" functions return an object of this class when 1282 All non-aggregate "aio_*" functions return an object of this class when
683 called in non-void context. 1283 called in non-void context.
684 1284
685 cancel $req 1285 cancel $req
686 Cancels the request, if possible. Has the effect of skipping 1286 Cancels the request, if possible. Has the effect of skipping
687 execution when entering the execute state and skipping calling the 1287 execution when entering the execute state and skipping calling the
688 callback when entering the the result state, but will leave the 1288 callback when entering the the result state, but will leave the
689 request otherwise untouched. That means that requests that currently 1289 request otherwise untouched (with the exception of readdir). That
690 execute will not be stopped and resources held by the request will 1290 means that requests that currently execute will not be stopped and
691 not be freed prematurely. 1291 resources held by the request will not be freed prematurely.
692 1292
693 cb $req $callback->(...) 1293 cb $req $callback->(...)
694 Replace (or simply set) the callback registered to the request. 1294 Replace (or simply set) the callback registered to the request.
695 1295
696 IO::AIO::GRP CLASS 1296 IO::AIO::GRP CLASS
… …
757 1357
758 $grp->cancel_subs 1358 $grp->cancel_subs
759 Cancel all subrequests and clears any feeder, but not the group 1359 Cancel all subrequests and clears any feeder, but not the group
760 request itself. Useful when you queued a lot of events but got a 1360 request itself. Useful when you queued a lot of events but got a
761 result early. 1361 result early.
1362
1363 The group request will finish normally (you cannot add requests to
1364 the group).
762 1365
763 $grp->result (...) 1366 $grp->result (...)
764 Set the result value(s) that will be passed to the group callback 1367 Set the result value(s) that will be passed to the group callback
765 when all subrequests have finished and set the groups errno to the 1368 when all subrequests have finished and set the groups errno to the
766 current value of errno (just like calling "errno" without an error 1369 current value of errno (just like calling "errno" without an error
… …
781 Sets a feeder/generator on this group: every group can have an 1384 Sets a feeder/generator on this group: every group can have an
782 attached generator that generates requests if idle. The idea behind 1385 attached generator that generates requests if idle. The idea behind
783 this is that, although you could just queue as many requests as you 1386 this is that, although you could just queue as many requests as you
784 want in a group, this might starve other requests for a potentially 1387 want in a group, this might starve other requests for a potentially
785 long time. For example, "aio_scandir" might generate hundreds of 1388 long time. For example, "aio_scandir" might generate hundreds of
786 thousands "aio_stat" requests, delaying any later requests for a 1389 thousands of "aio_stat" requests, delaying any later requests for a
787 long time. 1390 long time.
788 1391
789 To avoid this, and allow incremental generation of requests, you can 1392 To avoid this, and allow incremental generation of requests, you can
790 instead a group and set a feeder on it that generates those 1393 instead a group and set a feeder on it that generates those
791 requests. The feed callback will be called whenever there are few 1394 requests. The feed callback will be called whenever there are few
… …
826 SUPPORT FUNCTIONS 1429 SUPPORT FUNCTIONS
827 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1430 EVENT PROCESSING AND EVENT LOOP INTEGRATION
828 $fileno = IO::AIO::poll_fileno 1431 $fileno = IO::AIO::poll_fileno
829 Return the *request result pipe file descriptor*. This filehandle 1432 Return the *request result pipe file descriptor*. This filehandle
830 must be polled for reading by some mechanism outside this module 1433 must be polled for reading by some mechanism outside this module
831 (e.g. Event or select, see below or the SYNOPSIS). If the pipe 1434 (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
832 becomes readable you have to call "poll_cb" to check the results. 1435 pipe becomes readable you have to call "poll_cb" to check the
1436 results.
833 1437
834 See "poll_cb" for an example. 1438 See "poll_cb" for an example.
835 1439
836 IO::AIO::poll_cb 1440 IO::AIO::poll_cb
837 Process some outstanding events on the result pipe. You have to call 1441 Process some requests that have reached the result phase (i.e. they
838 this regularly. Returns 0 if all events could be processed, or -1 if 1442 have been executed but the results are not yet reported). You have
839 it returned earlier for whatever reason. Returns immediately when no 1443 to call this "regularly" to finish outstanding requests.
840 events are outstanding. The amount of events processed depends on
841 the settings of "IO::AIO::max_poll_req" and
842 "IO::AIO::max_poll_time".
843 1444
1445 Returns 0 if all events could be processed (or there were no events
1446 to process), or -1 if it returned earlier for whatever reason.
1447 Returns immediately when no events are outstanding. The amount of
1448 events processed depends on the settings of "IO::AIO::max_poll_req",
1449 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1450
844 If not all requests were processed for whatever reason, the 1451 If not all requests were processed for whatever reason, the poll
845 filehandle will still be ready when "poll_cb" returns, so normally 1452 file descriptor will still be ready when "poll_cb" returns, so
846 you don't have to do anything special to have it called later. 1453 normally you don't have to do anything special to have it called
1454 later.
1455
1456 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1457 becomes ready, it can be beneficial to call this function from loops
1458 which submit a lot of requests, to make sure the results get
1459 processed when they become available and not just when the loop is
1460 finished and the event loop takes over again. This function returns
1461 very fast when there are no outstanding requests.
847 1462
848 Example: Install an Event watcher that automatically calls 1463 Example: Install an Event watcher that automatically calls
849 IO::AIO::poll_cb with high priority: 1464 IO::AIO::poll_cb with high priority (more examples can be found in
1465 the SYNOPSIS section, at the top of this document):
850 1466
851 Event->io (fd => IO::AIO::poll_fileno, 1467 Event->io (fd => IO::AIO::poll_fileno,
852 poll => 'r', async => 1, 1468 poll => 'r', async => 1,
853 cb => \&IO::AIO::poll_cb); 1469 cb => \&IO::AIO::poll_cb);
1470
1471 IO::AIO::poll_wait
1472 Wait until either at least one request is in the result phase or no
1473 requests are outstanding anymore.
1474
1475 This is useful if you want to synchronously wait for some requests
1476 to become ready, without actually handling them.
1477
1478 See "nreqs" for an example.
1479
1480 IO::AIO::poll
1481 Waits until some requests have been handled.
1482
1483 Returns the number of requests processed, but is otherwise strictly
1484 equivalent to:
1485
1486 IO::AIO::poll_wait, IO::AIO::poll_cb
1487
1488 IO::AIO::flush
1489 Wait till all outstanding AIO requests have been handled.
1490
1491 Strictly equivalent to:
1492
1493 IO::AIO::poll_wait, IO::AIO::poll_cb
1494 while IO::AIO::nreqs;
1495
1496 This function can be useful at program aborts, to make sure
1497 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1498 already calls this function on normal exits), or when you are merely
1499 using "IO::AIO" for its more advanced functions, rather than for
1500 async I/O, e.g.:
1501
1502 my ($dirs, $nondirs);
1503 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1504 IO::AIO::flush;
1505 # $dirs, $nondirs are now set
854 1506
855 IO::AIO::max_poll_reqs $nreqs 1507 IO::AIO::max_poll_reqs $nreqs
856 IO::AIO::max_poll_time $seconds 1508 IO::AIO::max_poll_time $seconds
857 These set the maximum number of requests (default 0, meaning 1509 These set the maximum number of requests (default 0, meaning
858 infinity) that are being processed by "IO::AIO::poll_cb" in one 1510 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
882 # use a low priority so other tasks have priority 1534 # use a low priority so other tasks have priority
883 Event->io (fd => IO::AIO::poll_fileno, 1535 Event->io (fd => IO::AIO::poll_fileno,
884 poll => 'r', nice => 1, 1536 poll => 'r', nice => 1,
885 cb => &IO::AIO::poll_cb); 1537 cb => &IO::AIO::poll_cb);
886 1538
887 IO::AIO::poll_wait
888 If there are any outstanding requests and none of them in the result
889 phase, wait till the result filehandle becomes ready for reading
890 (simply does a "select" on the filehandle. This is useful if you
891 want to synchronously wait for some requests to finish).
892
893 See "nreqs" for an example.
894
895 IO::AIO::poll
896 Waits until some requests have been handled.
897
898 Returns the number of requests processed, but is otherwise strictly
899 equivalent to:
900
901 IO::AIO::poll_wait, IO::AIO::poll_cb
902
903 IO::AIO::flush
904 Wait till all outstanding AIO requests have been handled.
905
906 Strictly equivalent to:
907
908 IO::AIO::poll_wait, IO::AIO::poll_cb
909 while IO::AIO::nreqs;
910
911 CONTROLLING THE NUMBER OF THREADS 1539 CONTROLLING THE NUMBER OF THREADS
912 IO::AIO::min_parallel $nthreads 1540 IO::AIO::min_parallel $nthreads
913 Set the minimum number of AIO threads to $nthreads. The current 1541 Set the minimum number of AIO threads to $nthreads. The current
914 default is 8, which means eight asynchronous operations can execute 1542 default is 8, which means eight asynchronous operations can execute
915 concurrently at any one time (the number of outstanding requests, 1543 concurrently at any one time (the number of outstanding requests,
… …
944 1572
945 Under normal circumstances you don't need to call this function. 1573 Under normal circumstances you don't need to call this function.
946 1574
947 IO::AIO::max_idle $nthreads 1575 IO::AIO::max_idle $nthreads
948 Limit the number of threads (default: 4) that are allowed to idle 1576 Limit the number of threads (default: 4) that are allowed to idle
949 (i.e., threads that did not get a request to process within 10 1577 (i.e., threads that did not get a request to process within the idle
950 seconds). That means if a thread becomes idle while $nthreads other 1578 timeout (default: 10 seconds). That means if a thread becomes idle
951 threads are also idle, it will free its resources and exit. 1579 while $nthreads other threads are also idle, it will free its
1580 resources and exit.
952 1581
953 This is useful when you allow a large number of threads (e.g. 100 or 1582 This is useful when you allow a large number of threads (e.g. 100 or
954 1000) to allow for extremely high load situations, but want to free 1583 1000) to allow for extremely high load situations, but want to free
955 resources under normal circumstances (1000 threads can easily 1584 resources under normal circumstances (1000 threads can easily
956 consume 30MB of RAM). 1585 consume 30MB of RAM).
957 1586
958 The default is probably ok in most situations, especially if thread 1587 The default is probably ok in most situations, especially if thread
959 creation is fast. If thread creation is very slow on your system you 1588 creation is fast. If thread creation is very slow on your system you
960 might want to use larger values. 1589 might want to use larger values.
961 1590
1591 IO::AIO::idle_timeout $seconds
1592 Sets the minimum idle timeout (default 10) after which worker
1593 threads are allowed to exit. SEe "IO::AIO::max_idle".
1594
962 IO::AIO::max_outstanding $maxreqs 1595 IO::AIO::max_outstanding $maxreqs
963 This is a very bad function to use in interactive programs because
964 it blocks, and a bad way to reduce concurrency because it is
965 inexact: Better use an "aio_group" together with a feed callback.
966
967 Sets the maximum number of outstanding requests to $nreqs. If you do 1596 Sets the maximum number of outstanding requests to $nreqs. If you do
968 queue up more than this number of requests, the next call to the 1597 queue up more than this number of requests, the next call to
969 "poll_cb" (and "poll_some" and other functions calling "poll_cb") 1598 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
970 function will block until the limit is no longer exceeded. 1599 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1600 no longer exceeded.
971 1601
972 The default value is very large, so there is no practical limit on 1602 In other words, this setting does not enforce a queue limit, but can
1603 be used to make poll functions block if the limit is exceeded.
1604
1605 This is a bad function to use in interactive programs because it
1606 blocks, and a bad way to reduce concurrency because it is inexact.
1607 If you need to issue many requests without being able to call a poll
1608 function on demand, it is better to use an "aio_group" together with
1609 a feed callback.
1610
1611 Its main use is in scripts without an event loop - when you want to
1612 stat a lot of files, you can write something like this:
1613
1614 IO::AIO::max_outstanding 32;
1615
1616 for my $path (...) {
1617 aio_stat $path , ...;
1618 IO::AIO::poll_cb;
1619 }
1620
1621 IO::AIO::flush;
1622
1623 The call to "poll_cb" inside the loop will normally return
1624 instantly, allowing the loop to progress, but as soon as more than
1625 32 requests are in-flight, it will block until some requests have
1626 been handled. This keeps the loop from pushing a large number of
1627 "aio_stat" requests onto the queue (which, with many paths to stat,
1628 can use up a lot of memory).
1629
1630 The default value for "max_outstanding" is very large, so there is
973 the number of outstanding requests. 1631 no practical limit on the number of outstanding requests.
974
975 You can still queue as many requests as you want. Therefore,
976 "max_outstanding" is mainly useful in simple scripts (with low
977 values) or as a stop gap to shield against fatal memory overflow
978 (with large values).
979 1632
980 STATISTICAL INFORMATION 1633 STATISTICAL INFORMATION
981 IO::AIO::nreqs 1634 IO::AIO::nreqs
982 Returns the number of requests currently in the ready, execute or 1635 Returns the number of requests currently in the ready, execute or
983 pending states (i.e. for which their callback has not been invoked 1636 pending states (i.e. for which their callback has not been invoked
… …
994 1647
995 IO::AIO::npending 1648 IO::AIO::npending
996 Returns the number of requests currently in the pending state 1649 Returns the number of requests currently in the pending state
997 (executed, but not yet processed by poll_cb). 1650 (executed, but not yet processed by poll_cb).
998 1651
1652 SUBSECOND STAT TIME ACCESS
1653 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1654 generally find access/modification and change times with subsecond time
1655 accuracy of the system supports it, but perl's built-in functions only
1656 return the integer part.
1657
1658 The following functions return the timestamps of the most recent stat
1659 with subsecond precision on most systems and work both after
1660 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1661 value is only meaningful after a successful "stat"/"lstat" call, or
1662 during/after a successful "aio_stat"/"aio_lstat" callback.
1663
1664 This is similar to the Time::HiRes "stat" functions, but can return full
1665 resolution without rounding and work with standard perl "stat",
1666 alleviating the need to call the special "Time::HiRes" functions, which
1667 do not act like their perl counterparts.
1668
1669 On operating systems or file systems where subsecond time resolution is
1670 not supported or could not be detected, a fractional part of 0 is
1671 returned, so it is always safe to call these functions.
1672
1673 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1674 IO::AIO::st_btime
1675 Return the access, modication, change or birth time, respectively,
1676 including fractional part. Due to the limited precision of floating
1677 point, the accuracy on most platforms is only a bit better than
1678 milliseconds for times around now - see the *nsec* function family,
1679 below, for full accuracy.
1680
1681 File birth time is only available when the OS and perl support it
1682 (on FreeBSD and NetBSD at the time of this writing, although support
1683 is adaptive, so if your OS/perl gains support, IO::AIO can take
1684 advantage of it). On systems where it isn't available, 0 is
1685 currently returned, but this might change to "undef" in a future
1686 version.
1687
1688 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1689 Returns access, modification, change and birth time all in one go,
1690 and maybe more times in the future version.
1691
1692 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1693 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1694 Return the fractional access, modifcation, change or birth time, in
1695 nanoseconds, as an integer in the range 0 to 999999999.
1696
1697 Note that no accessors are provided for access, modification and
1698 change times - you need to get those from "stat _" if required ("int
1699 IO::AIO::st_atime" and so on will *not* generally give you the
1700 correct value).
1701
1702 $seconds = IO::AIO::st_btimesec
1703 The (integral) seconds part of the file birth time, if available.
1704
1705 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1706 Like the functions above, but returns all four times in one go (and
1707 maybe more in future versions).
1708
1709 $counter = IO::AIO::st_gen
1710 Returns the generation counter (in practice this is just a random
1711 number) of the file. This is only available on platforms which have
1712 this member in their "struct stat" (most BSDs at the time of this
1713 writing) and generally only to the root usert. If unsupported, 0 is
1714 returned, but this might change to "undef" in a future version.
1715
1716 Example: print the high resolution modification time of /etc, using
1717 "stat", and "IO::AIO::aio_stat".
1718
1719 if (stat "/etc") {
1720 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1721 }
1722
1723 IO::AIO::aio_stat "/etc", sub {
1724 $_[0]
1725 and return;
1726
1727 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1728 };
1729
1730 IO::AIO::flush;
1731
1732 Output of the awbove on my system, showing reduced and full accuracy:
1733
1734 stat(/etc) mtime: 1534043702.020808
1735 aio_stat(/etc) mtime: 1534043702.020807792
1736
1737 MISCELLANEOUS FUNCTIONS
1738 IO::AIO implements some functions that are useful when you want to use
1739 some "Advanced I/O" function not available to in Perl, without going the
1740 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1741 counterpart.
1742
1743 $retval = IO::AIO::fexecve $fh, $argv, $envp
1744 A more-or-less direct equivalent to the POSIX "fexecve" functions,
1745 which allows you to specify the program to be executed via a file
1746 descriptor (or handle). Returns -1 and sets errno to "ENOSYS" if not
1747 available.
1748
1749 $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data =
1750 undef
1751 Calls the GNU/Linux mount syscall with the given arguments. All
1752 except $flags are strings, and if $data is "undef", a "NULL" will be
1753 passed.
1754
1755 The following values for $flags are available:
1756
1757 "IO::AIO::MS_RDONLY", "IO::AIO::MS_NOSUID", "IO::AIO::MS_NODEV",
1758 "IO::AIO::MS_NOEXEC", "IO::AIO::MS_SYNCHRONOUS",
1759 "IO::AIO::MS_REMOUNT", "IO::AIO::MS_MANDLOCK",
1760 "IO::AIO::MS_DIRSYNC", "IO::AIO::MS_NOATIME",
1761 "IO::AIO::MS_NODIRATIME", "IO::AIO::MS_BIND", "IO::AIO::MS_MOVE",
1762 "IO::AIO::MS_REC", "IO::AIO::MS_SILENT", "IO::AIO::MS_POSIXACL",
1763 "IO::AIO::MS_UNBINDABLE", "IO::AIO::MS_PRIVATE",
1764 "IO::AIO::MS_SLAVE", "IO::AIO::MS_SHARED", "IO::AIO::MS_RELATIME",
1765 "IO::AIO::MS_KERNMOUNT", "IO::AIO::MS_I_VERSION",
1766 "IO::AIO::MS_STRICTATIME", "IO::AIO::MS_LAZYTIME",
1767 "IO::AIO::MS_ACTIVE", "IO::AIO::MS_NOUSER", "IO::AIO::MS_RMT_MASK",
1768 "IO::AIO::MS_MGC_VAL" and "IO::AIO::MS_MGC_MSK".
1769
1770 $retval = IO::AIO::umount $path, $flags = 0
1771 Invokes the GNU/Linux "umount" or "umount2" syscalls. Always calls
1772 "umount" if $flags is 0, otherwqise always tries to call "umount2".
1773
1774 The following $flags are available:
1775
1776 "IO::AIO::MNT_FORCE", "IO::AIO::MNT_DETACH", "IO::AIO::MNT_EXPIRE"
1777 and "IO::AIO::UMOUNT_NOFOLLOW".
1778
1779 $numfd = IO::AIO::get_fdlimit
1780 Tries to find the current file descriptor limit and returns it, or
1781 "undef" and sets $! in case of an error. The limit is one larger
1782 than the highest valid file descriptor number.
1783
1784 IO::AIO::min_fdlimit [$numfd]
1785 Try to increase the current file descriptor limit(s) to at least
1786 $numfd by changing the soft or hard file descriptor resource limit.
1787 If $numfd is missing, it will try to set a very high limit, although
1788 this is not recommended when you know the actual minimum that you
1789 require.
1790
1791 If the limit cannot be raised enough, the function makes a
1792 best-effort attempt to increase the limit as much as possible, using
1793 various tricks, while still failing. You can query the resulting
1794 limit using "IO::AIO::get_fdlimit".
1795
1796 If an error occurs, returns "undef" and sets $!, otherwise returns
1797 true.
1798
1799 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1800 Calls the "eio_sendfile_sync" function, which is like
1801 "aio_sendfile", but is blocking (this makes most sense if you know
1802 the input data is likely cached already and the output filehandle is
1803 set to non-blocking operations).
1804
1805 Returns the number of bytes copied, or -1 on error.
1806
1807 IO::AIO::fadvise $fh, $offset, $len, $advice
1808 Simply calls the "posix_fadvise" function (see its manpage for
1809 details). The following advice constants are available:
1810 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1811 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1812 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1813
1814 On systems that do not implement "posix_fadvise", this function
1815 returns ENOSYS, otherwise the return value of "posix_fadvise".
1816
1817 IO::AIO::madvise $scalar, $offset, $len, $advice
1818 Simply calls the "posix_madvise" function (see its manpage for
1819 details). The following advice constants are available:
1820 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1821 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1822 "IO::AIO::MADV_DONTNEED".
1823
1824 If $offset is negative, counts from the end. If $length is negative,
1825 the remaining length of the $scalar is used. If possible, $length
1826 will be reduced to fit into the $scalar.
1827
1828 On systems that do not implement "posix_madvise", this function
1829 returns ENOSYS, otherwise the return value of "posix_madvise".
1830
1831 IO::AIO::mprotect $scalar, $offset, $len, $protect
1832 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1833 $scalar (see its manpage for details). The following protect
1834 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1835 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1836
1837 If $offset is negative, counts from the end. If $length is negative,
1838 the remaining length of the $scalar is used. If possible, $length
1839 will be reduced to fit into the $scalar.
1840
1841 On systems that do not implement "mprotect", this function returns
1842 ENOSYS, otherwise the return value of "mprotect".
1843
1844 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1845 Memory-maps a file (or anonymous memory range) and attaches it to
1846 the given $scalar, which will act like a string scalar. Returns true
1847 on success, and false otherwise.
1848
1849 The scalar must exist, but its contents do not matter - this means
1850 you cannot use a nonexistant array or hash element. When in doubt,
1851 "undef" the scalar first.
1852
1853 The only operations allowed on the mmapped scalar are
1854 "substr"/"vec", which don't change the string length, and most
1855 read-only operations such as copying it or searching it with regexes
1856 and so on.
1857
1858 Anything else is unsafe and will, at best, result in memory leaks.
1859
1860 The memory map associated with the $scalar is automatically removed
1861 when the $scalar is undef'd or destroyed, or when the
1862 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1863
1864 This calls the "mmap"(2) function internally. See your system's
1865 manual page for details on the $length, $prot and $flags parameters.
1866
1867 The $length must be larger than zero and smaller than the actual
1868 filesize.
1869
1870 $prot is a combination of "IO::AIO::PROT_NONE",
1871 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1872 "IO::AIO::PROT_WRITE",
1873
1874 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1875 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1876 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1877 "MAP_ANON" if your system only provides this constant),
1878 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1879 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1880 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1881 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
1882 "IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
1883 "IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1884
1885 If $fh is "undef", then a file descriptor of -1 is passed.
1886
1887 $offset is the offset from the start of the file - it generally must
1888 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1889
1890 Example:
1891
1892 use Digest::MD5;
1893 use IO::AIO;
1894
1895 open my $fh, "<verybigfile"
1896 or die "$!";
1897
1898 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1899 or die "verybigfile: $!";
1900
1901 my $fast_md5 = md5 $data;
1902
1903 IO::AIO::munmap $scalar
1904 Removes a previous mmap and undefines the $scalar.
1905
1906 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1907 $new_address = 0]
1908 Calls the Linux-specific mremap(2) system call. The $scalar must
1909 have been mapped by "IO::AIO::mmap", and $flags must currently
1910 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1911
1912 Returns true if successful, and false otherwise. If the underlying
1913 mmapped region has changed address, then the true value has the
1914 numerical value 1, otherwise it has the numerical value 0:
1915
1916 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1917 or die "mremap: $!";
1918
1919 if ($success*1) {
1920 warn "scalar has chanegd address in memory\n";
1921 }
1922
1923 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1924 implemented, but not supported and might go away in a future
1925 version.
1926
1927 On systems where this call is not supported or is not emulated, this
1928 call returns falls and sets $! to "ENOSYS".
1929
1930 IO::AIO::mlockall $flags
1931 Calls the "eio_mlockall_sync" function, which is like
1932 "aio_mlockall", but is blocking.
1933
1934 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1935 Calls the "munlock" function, undoing the effects of a previous
1936 "aio_mlock" call (see its description for details).
1937
1938 IO::AIO::munlockall
1939 Calls the "munlockall" function.
1940
1941 On systems that do not implement "munlockall", this function returns
1942 ENOSYS, otherwise the return value of "munlockall".
1943
1944 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1945 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1946 socket and return the new file handle on success, or sets $! and
1947 returns "undef" on error.
1948
1949 The remote name of the new socket will be stored in $sockaddr, which
1950 will be extended to allow for at least $sockaddr_maxlen octets. If
1951 the socket name does not fit into $sockaddr_maxlen octets, this is
1952 signaled by returning a longer string in $sockaddr, which might or
1953 might not be truncated.
1954
1955 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1956 $sockaddr_maxlen.
1957
1958 The main reasons to use this syscall rather than portable accept(2)
1959 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1960 and you can accept name-less sockets by specifying 0 for
1961 $sockaddr_maxlen, which is sadly not possible with perl's interface
1962 to "accept".
1963
1964 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1965 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1966 $w_off are "undef", then "NULL" is passed for these, otherwise they
1967 should be the file offset.
1968
1969 $r_fh and $w_fh should not refer to the same file, as splice might
1970 silently corrupt the data in this case.
1971
1972 The following symbol flag values are available:
1973 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1974 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1975
1976 See the splice(2) manpage for details.
1977
1978 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1979 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1980 description for "IO::AIO::splice" above for details.
1981
1982 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1983 Attempts to query or change the pipe buffer size. Obviously works
1984 only on pipes, and currently works only on GNU/Linux systems, and
1985 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1986 influence pipe buffer size on other systems, drop me a note.
1987
1988 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1989 This is a direct interface to the Linux pipe2(2) system call. If
1990 $flags is missing or 0, then this should be the same as a call to
1991 perl's built-in "pipe" function and create a new pipe, and works on
1992 systems that lack the pipe2 syscall. On win32, this case invokes
1993 "_pipe (..., 4096, O_BINARY)".
1994
1995 If $flags is non-zero, it tries to invoke the pipe2 system call with
1996 the given flags (Linux 2.6.27, glibc 2.9).
1997
1998 On success, the read and write file handles are returned.
1999
2000 On error, nothing will be returned. If the pipe2 syscall is missing
2001 and $flags is non-zero, fails with "ENOSYS".
2002
2003 Please refer to pipe2(2) for more info on the $flags, but at the
2004 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
2005 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
2006 supported.
2007
2008 Example: create a pipe race-free w.r.t. threads and fork:
2009
2010 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
2011 or die "pipe2: $!\n";
2012
2013 $fh = IO::AIO::memfd_create $pathname[, $flags]
2014 This is a direct interface to the Linux memfd_create(2) system call.
2015 The (unhelpful) default for $flags is 0, but your default should be
2016 "IO::AIO::MFD_CLOEXEC".
2017
2018 On success, the new memfd filehandle is returned, otherwise returns
2019 "undef". If the memfd_create syscall is missing, fails with
2020 "ENOSYS".
2021
2022 Please refer to memfd_create(2) for more info on this call.
2023
2024 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
2025 "IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
2026 "IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
2027
2028 Example: create a new memfd.
2029
2030 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
2031 or die "memfd_create: $!\n";
2032
2033 $fh = IO::AIO::pidfd_open $pid[, $flags]
2034 This is an interface to the Linux pidfd_open(2) system call. The
2035 default for $flags is 0.
2036
2037 On success, a new pidfd filehandle is returned (that is already set
2038 to close-on-exec), otherwise returns "undef". If the syscall is
2039 missing, fails with "ENOSYS".
2040
2041 Example: open pid 6341 as pidfd.
2042
2043 my $fh = IO::AIO::pidfd_open 6341
2044 or die "pidfd_open: $!\n";
2045
2046 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
2047 $flags]]
2048 This is an interface to the Linux pidfd_send_signal system call. The
2049 default for $siginfo is "undef" and the default for $flags is 0.
2050
2051 Returns the system call status. If the syscall is missing, fails
2052 with "ENOSYS".
2053
2054 When specified, $siginfo must be a reference to a hash with one or
2055 more of the following members:
2056
2057 code - the "si_code" member
2058 pid - the "si_pid" member
2059 uid - the "si_uid" member
2060 value_int - the "si_value.sival_int" member
2061 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2062
2063 Example: send a SIGKILL to the specified process.
2064
2065 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2066 and die "pidfd_send_signal: $!\n";
2067
2068 Example: send a SIGKILL to the specified process with extra data.
2069
2070 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2071 and die "pidfd_send_signal: $!\n";
2072
2073 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2074 This is an interface to the Linux pidfd_getfd system call. The
2075 default for $flags is 0.
2076
2077 On success, returns a dup'ed copy of the target file descriptor
2078 (specified as an integer) returned (that is already set to
2079 close-on-exec), otherwise returns "undef". If the syscall is
2080 missing, fails with "ENOSYS".
2081
2082 Example: get a copy of standard error of another process and print
2083 soemthing to it.
2084
2085 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2086 or die "pidfd_getfd: $!\n";
2087 print $errfh "stderr\n";
2088
2089 $fh = IO::AIO::eventfd [$initval, [$flags]]
2090 This is a direct interface to the Linux eventfd(2) system call. The
2091 (unhelpful) defaults for $initval and $flags are 0 for both.
2092
2093 On success, the new eventfd filehandle is returned, otherwise
2094 returns "undef". If the eventfd syscall is missing, fails with
2095 "ENOSYS".
2096
2097 Please refer to eventfd(2) for more info on this call.
2098
2099 The following symbol flag values are available:
2100 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2101 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2102
2103 Example: create a new eventfd filehandle:
2104
2105 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2106 or die "eventfd: $!\n";
2107
2108 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2109 This is a direct interface to the Linux timerfd_create(2) system
2110 call. The (unhelpful) default for $flags is 0, but your default
2111 should be "IO::AIO::TFD_CLOEXEC".
2112
2113 On success, the new timerfd filehandle is returned, otherwise
2114 returns "undef". If the timerfd_create syscall is missing, fails
2115 with "ENOSYS".
2116
2117 Please refer to timerfd_create(2) for more info on this call.
2118
2119 The following $clockid values are available:
2120 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2121 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2122 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2123 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2124
2125 The following $flags values are available (Linux 2.6.27):
2126 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2127
2128 Example: create a new timerfd and set it to one-second repeated
2129 alarms, then wait for two alarms:
2130
2131 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2132 or die "timerfd_create: $!\n";
2133
2134 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2135 or die "timerfd_settime: $!\n";
2136
2137 for (1..2) {
2138 8 == sysread $fh, my $buf, 8
2139 or die "timerfd read failure\n";
2140
2141 printf "number of expirations (likely 1): %d\n",
2142 unpack "Q", $buf;
2143 }
2144
2145 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2146 $new_interval, $nbw_value
2147 This is a direct interface to the Linux timerfd_settime(2) system
2148 call. Please refer to its manpage for more info on this call.
2149
2150 The new itimerspec is specified using two (possibly fractional)
2151 second values, $new_interval and $new_value).
2152
2153 On success, the current interval and value are returned (as per
2154 "timerfd_gettime"). On failure, the empty list is returned.
2155
2156 The following $flags values are available:
2157 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2158
2159 See "IO::AIO::timerfd_create" for a full example.
2160
2161 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2162 This is a direct interface to the Linux timerfd_gettime(2) system
2163 call. Please refer to its manpage for more info on this call.
2164
2165 On success, returns the current values of interval and value for the
2166 given timerfd (as potentially fractional second values). On failure,
2167 the empty list is returned.
2168
2169EVENT LOOP INTEGRATION
2170 It is recommended to use AnyEvent::AIO to integrate IO::AIO
2171 automatically into many event loops:
2172
2173 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
2174 use AnyEvent::AIO;
2175
2176 You can also integrate IO::AIO manually into many event loops, here are
2177 some examples of how to do this:
2178
2179 # EV integration
2180 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
2181
2182 # Event integration
2183 Event->io (fd => IO::AIO::poll_fileno,
2184 poll => 'r',
2185 cb => \&IO::AIO::poll_cb);
2186
2187 # Glib/Gtk2 integration
2188 add_watch Glib::IO IO::AIO::poll_fileno,
2189 in => sub { IO::AIO::poll_cb; 1 };
2190
2191 # Tk integration
2192 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
2193 readable => \&IO::AIO::poll_cb);
2194
2195 # Danga::Socket integration
2196 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
2197 \&IO::AIO::poll_cb);
2198
999 FORK BEHAVIOUR 2199 FORK BEHAVIOUR
1000 This module should do "the right thing" when the process using it forks: 2200 Usage of pthreads in a program changes the semantics of fork
2201 considerably. Specifically, only async-safe functions can be called
2202 after fork. Perl doesn't know about this, so in general, you cannot call
2203 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2204 uses pthreads, so this applies, but many other extensions and (for
2205 inexplicable reasons) perl itself often is linked against pthreads, so
2206 this limitation applies to quite a lot of perls.
1001 2207
1002 Before the fork, IO::AIO enters a quiescent state where no requests can 2208 This module no longer tries to fight your OS, or POSIX. That means
1003 be added in other threads and no results will be processed. After the 2209 IO::AIO only works in the process that loaded it. Forking is fully
1004 fork the parent simply leaves the quiescent state and continues 2210 supported, but using IO::AIO in the child is not.
1005 request/result processing, while the child frees the request/result
1006 queue (so that the requests started before the fork will only be handled
1007 in the parent). Threads will be started on demand until the limit set in
1008 the parent process has been reached again.
1009 2211
1010 In short: the parent will, after a short pause, continue as if fork had 2212 You might get around by not *using* IO::AIO before (or after) forking.
1011 not been called, while the child will act as if IO::AIO has not been 2213 You could also try to call the IO::AIO::reinit function in the child:
1012 used yet. 2214
2215 IO::AIO::reinit
2216 Abandons all current requests and I/O threads and simply
2217 reinitialises all data structures. This is not an operation
2218 supported by any standards, but happens to work on GNU/Linux and
2219 some newer BSD systems.
2220
2221 The only reasonable use for this function is to call it after
2222 forking, if "IO::AIO" was used in the parent. Calling it while
2223 IO::AIO is active in the process will result in undefined behaviour.
2224 Calling it at any time will also result in any undefined (by POSIX)
2225 behaviour.
2226
2227 LINUX-SPECIFIC CALLS
2228 When a call is documented as "linux-specific" then this means it
2229 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2230 availability and compatibility of such calls regardless of the platform
2231 it is compiled on, so platforms such as FreeBSD which often implement
2232 these calls will work. When in doubt, call them and see if they fail wth
2233 "ENOSYS".
1013 2234
1014 MEMORY USAGE 2235 MEMORY USAGE
1015 Per-request usage: 2236 Per-request usage:
1016 2237
1017 Each aio request uses - depending on your architecture - around 100-200 2238 Each aio request uses - depending on your architecture - around 100-200
… …
1028 In the execution phase, some aio requests require more memory for 2249 In the execution phase, some aio requests require more memory for
1029 temporary buffers, and each thread requires a stack and other data 2250 temporary buffers, and each thread requires a stack and other data
1030 structures (usually around 16k-128k, depending on the OS). 2251 structures (usually around 16k-128k, depending on the OS).
1031 2252
1032KNOWN BUGS 2253KNOWN BUGS
1033 Known bugs will be fixed in the next release. 2254 Known bugs will be fixed in the next release :)
2255
2256KNOWN ISSUES
2257 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2258 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2259 non-created hash slots or other scalars I didn't think of. It's best to
2260 avoid such and either use scalar variables or making sure that the
2261 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2262
2263 I am not sure anything can be done about this, so this is considered a
2264 known issue, rather than a bug.
1034 2265
1035SEE ALSO 2266SEE ALSO
1036 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2267 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1037 more natural syntax. 2268 more natural syntax and IO::FDPass for file descriptor passing.
1038 2269
1039AUTHOR 2270AUTHOR
1040 Marc Lehmann <schmorp@schmorp.de> 2271 Marc Lehmann <schmorp@schmorp.de>
1041 http://home.schmorp.de/ 2272 http://home.schmorp.de/
1042 2273

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