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Revision 1.47 by root, Fri May 27 00:44:49 2011 UTC

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2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous 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
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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, urxvt, pureperl...)
30 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33 # EV integration
34 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
35
36 # Event integration
37 Event->io (fd => IO::AIO::poll_fileno,
38 poll => 'r',
39 cb => \&IO::AIO::poll_cb);
40
41 # Glib/Gtk2 integration
42 add_watch Glib::IO IO::AIO::poll_fileno,
43 in => sub { IO::AIO::poll_cb; 1 };
44
45 # Tk integration
46 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
47 readable => \&IO::AIO::poll_cb);
48
49 # Danga::Socket integration
50 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
51 \&IO::AIO::poll_cb);
52
53DESCRIPTION 29DESCRIPTION
54 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
55 operating system supports. 31 operating system supports. It is implemented as an interface to "libeio"
32 (<http://software.schmorp.de/pkg/libeio.html>).
56 33
57 Asynchronous means that operations that can normally block your program 34 Asynchronous means that operations that can normally block your program
58 (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
59 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
60 extremely useful for programs that need to stay interactive even when 37 extremely useful for programs that need to stay interactive even when
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65 operations concurrently. 42 operations concurrently.
66 43
67 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
68 sockets), using these functions on file descriptors that support 45 sockets), using these functions on file descriptors that support
69 nonblocking operation (again, sockets, pipes etc.) is very inefficient. 46 nonblocking operation (again, sockets, pipes etc.) is very inefficient.
70 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
71 naturally fit into such an event loop itself. 48 naturally fit into such an event loop itself.
72 49
73 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
74 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
75 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
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84 it is currently not reentrant in any way, so use appropriate locking 61 it is currently not reentrant in any way, so use appropriate locking
85 yourself, always call "poll_cb" from within the same thread, or never 62 yourself, always call "poll_cb" from within the same thread, or never
86 call "poll_cb" (or other "aio_" functions) recursively. 63 call "poll_cb" (or other "aio_" functions) recursively.
87 64
88 EXAMPLE 65 EXAMPLE
89 This is a simple example that uses the Event module and loads 66 This is a simple example that uses the EV module and loads /etc/passwd
90 /etc/passwd asynchronously: 67 asynchronously:
91 68
92 use Fcntl; 69 use Fcntl;
93 use Event; 70 use EV;
94 use IO::AIO; 71 use IO::AIO;
95 72
96 # register the IO::AIO callback with Event 73 # register the IO::AIO callback with EV
97 Event->io (fd => IO::AIO::poll_fileno, 74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98 poll => 'r',
99 cb => \&IO::AIO::poll_cb);
100 75
101 # queue the request to open /etc/passwd 76 # queue the request to open /etc/passwd
102 aio_open "/etc/passwd", O_RDONLY, 0, sub { 77 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
103 my $fh = shift 78 my $fh = shift
104 or die "error while opening: $!"; 79 or die "error while opening: $!";
105 80
106 # stat'ing filehandles is generally non-blocking 81 # stat'ing filehandles is generally non-blocking
107 my $size = -s $fh; 82 my $size = -s $fh;
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116 91
117 # file contents now in $contents 92 # file contents now in $contents
118 print $contents; 93 print $contents;
119 94
120 # exit event loop and program 95 # exit event loop and program
121 Event::unloop; 96 EV::unloop;
122 }; 97 };
123 }; 98 };
124 99
125 # possibly queue up other requests, or open GUI windows, 100 # possibly queue up other requests, or open GUI windows,
126 # check for sockets etc. etc. 101 # check for sockets etc. etc.
127 102
128 # process events as long as there are some: 103 # process events as long as there are some:
129 Event::loop; 104 EV::loop;
130 105
131REQUEST ANATOMY AND LIFETIME 106REQUEST ANATOMY AND LIFETIME
132 Every "aio_*" function creates a request. which is a C data structure 107 Every "aio_*" function creates a request. which is a C data structure
133 not directly visible to Perl. 108 not directly visible to Perl.
134 109
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170 anymore (except possibly for the Perl object, but its connection to 145 anymore (except possibly for the Perl object, but its connection to
171 the actual aio request is severed and calling its methods will 146 the actual aio request is severed and calling its methods will
172 either do nothing or result in a runtime error). 147 either do nothing or result in a runtime error).
173 148
174FUNCTIONS 149FUNCTIONS
150 QUICK OVERVIEW
151 This section simply lists the prototypes of the most important functions
152 for quick reference. See the following sections for function-by-function
153 documentation.
154
155 aio_open $pathname, $flags, $mode, $callback->($fh)
156 aio_close $fh, $callback->($status)
157 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160 aio_readahead $fh,$offset,$length, $callback->($retval)
161 aio_stat $fh_or_path, $callback->($status)
162 aio_lstat $fh, $callback->($status)
163 aio_statvfs $fh_or_path, $callback->($statvfs)
164 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
166 aio_truncate $fh_or_path, $offset, $callback->($status)
167 aio_chmod $fh_or_path, $mode, $callback->($status)
168 aio_unlink $pathname, $callback->($status)
169 aio_mknod $path, $mode, $dev, $callback->($status)
170 aio_link $srcpath, $dstpath, $callback->($status)
171 aio_symlink $srcpath, $dstpath, $callback->($status)
172 aio_readlink $path, $callback->($link)
173 aio_rename $srcpath, $dstpath, $callback->($status)
174 aio_mkdir $pathname, $mode, $callback->($status)
175 aio_rmdir $pathname, $callback->($status)
176 aio_readdir $pathname, $callback->($entries)
177 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
180 aio_load $path, $data, $callback->($status)
181 aio_copy $srcpath, $dstpath, $callback->($status)
182 aio_move $srcpath, $dstpath, $callback->($status)
183 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184 aio_rmtree $path, $callback->($status)
185 aio_sync $callback->($status)
186 aio_fsync $fh, $callback->($status)
187 aio_fdatasync $fh, $callback->($status)
188 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189 aio_pathsync $path, $callback->($status)
190 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
193 aio_mlockall $flags, $callback->($status)
194 aio_group $callback->(...)
195 aio_nop $callback->()
196
197 $prev_pri = aioreq_pri [$pri]
198 aioreq_nice $pri_adjust
199
200 IO::AIO::poll_wait
201 IO::AIO::poll_cb
202 IO::AIO::poll
203 IO::AIO::flush
204 IO::AIO::max_poll_reqs $nreqs
205 IO::AIO::max_poll_time $seconds
206 IO::AIO::min_parallel $nthreads
207 IO::AIO::max_parallel $nthreads
208 IO::AIO::max_idle $nthreads
209 IO::AIO::idle_timeout $seconds
210 IO::AIO::max_outstanding $maxreqs
211 IO::AIO::nreqs
212 IO::AIO::nready
213 IO::AIO::npending
214
215 IO::AIO::sendfile $ofh, $ifh, $offset, $count
216 IO::AIO::fadvise $fh, $offset, $len, $advice
217 IO::AIO::madvise $scalar, $offset, $length, $advice
218 IO::AIO::mprotect $scalar, $offset, $length, $protect
219 IO::AIO::munlock $scalar, $offset = 0, $length = undef
220 IO::AIO::munlockall
221
175 AIO REQUEST FUNCTIONS 222 AIO REQUEST FUNCTIONS
176 All the "aio_*" calls are more or less thin wrappers around the syscall 223 All the "aio_*" calls are more or less thin wrappers around the syscall
177 with the same name (sans "aio_"). The arguments are similar or 224 with the same name (sans "aio_"). The arguments are similar or
178 identical, and they all accept an additional (and optional) $callback 225 identical, and they all accept an additional (and optional) $callback
179 argument which must be a code reference. This code reference will get 226 argument which must be a code reference. This code reference will get
180 called with the syscall return code (e.g. most syscalls return -1 on 227 called with the syscall return code (e.g. most syscalls return -1 on
181 error, unlike perl, which usually delivers "false") as it's sole 228 error, unlike perl, which usually delivers "false") as its sole argument
182 argument when the given syscall has been executed asynchronously. 229 after the given syscall has been executed asynchronously.
183 230
184 All functions expecting a filehandle keep a copy of the filehandle 231 All functions expecting a filehandle keep a copy of the filehandle
185 internally until the request has finished. 232 internally until the request has finished.
186 233
187 All functions return request objects of type IO::AIO::REQ that allow 234 All functions return request objects of type IO::AIO::REQ that allow
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200 the user environment, d) use Glib::filename_from_unicode on unicode 247 the user environment, d) use Glib::filename_from_unicode on unicode
201 filenames or e) use something else to ensure your scalar has the correct 248 filenames or e) use something else to ensure your scalar has the correct
202 contents. 249 contents.
203 250
204 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 251 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
205 handles correctly wether it is set or not. 252 handles correctly whether it is set or not.
206 253
207 $prev_pri = aioreq_pri [$pri] 254 $prev_pri = aioreq_pri [$pri]
208 Returns the priority value that would be used for the next request 255 Returns the priority value that would be used for the next request
209 and, if $pri is given, sets the priority for the next aio request. 256 and, if $pri is given, sets the priority for the next aio request.
210 257
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250 will be modified by the umask in effect then the request is being 297 will be modified by the umask in effect then the request is being
251 executed, so better never change the umask. 298 executed, so better never change the umask.
252 299
253 Example: 300 Example:
254 301
255 aio_open "/etc/passwd", O_RDONLY, 0, sub { 302 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
256 if ($_[0]) { 303 if ($_[0]) {
257 print "open successful, fh is $_[0]\n"; 304 print "open successful, fh is $_[0]\n";
258 ... 305 ...
259 } else { 306 } else {
260 die "open failed: $!\n"; 307 die "open failed: $!\n";
261 } 308 }
262 }; 309 };
263 310
311 In addition to all the common open modes/flags ("O_RDONLY",
312 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
313 "O_APPEND"), the following POSIX and non-POSIX constants are
314 available (missing ones on your system are, as usual, 0):
315
316 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
317 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
318 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
319
264 aio_close $fh, $callback->($status) 320 aio_close $fh, $callback->($status)
265 Asynchronously close a file and call the callback with the result 321 Asynchronously close a file and call the callback with the result
266 code. 322 code.
267 323
268 Unfortunately, you can't do this to perl. Perl *insists* very 324 Unfortunately, you can't do this to perl. Perl *insists* very
269 strongly on closing the file descriptor associated with the 325 strongly on closing the file descriptor associated with the
270 filehandle itself. Here is what aio_close will try: 326 filehandle itself.
271 327
272 1. dup()licate the fd 328 Therefore, "aio_close" will not close the filehandle - instead it
273 2. asynchronously close() the duplicated fd 329 will use dup2 to overwrite the file descriptor with the write-end of
274 3. dup()licate the fd once more 330 a pipe (the pipe fd will be created on demand and will be cached).
275 4. let perl close() the filehandle
276 5. asynchronously close the duplicated fd
277 331
278 The idea is that the first close() flushes stuff to disk that 332 Or in other words: the file descriptor will be closed, but it will
279 closing an fd will flush, so when perl closes the fd, nothing much 333 not be free for reuse until the perl filehandle is closed.
280 will need to be flushed. The second async. close() will then flush
281 stuff to disk that closing the last fd to the file will flush.
282
283 Just FYI, SuSv3 has this to say on close:
284
285 All outstanding record locks owned by the process on the file
286 associated with the file descriptor shall be removed.
287
288 If fildes refers to a socket, close() shall cause the socket to be
289 destroyed. ... close() shall block for up to the current linger
290 interval until all data is transmitted.
291 [this actually sounds like a specification bug, but who knows]
292
293 And at least Linux additionally actually flushes stuff on every
294 close, even when the file itself is still open.
295
296 Sounds enourmously inefficient and complicated? Yes... please show
297 me how to nuke perl's fd out of existence...
298 334
299 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 335 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
300 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 336 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
301 Reads or writes $length bytes from the specified $fh and $offset 337 Reads or writes $length bytes from or to the specified $fh and
302 into the scalar given by $data and offset $dataoffset and calls the 338 $offset into the scalar given by $data and offset $dataoffset and
303 callback without the actual number of bytes read (or -1 on error, 339 calls the callback without the actual number of bytes read (or -1 on
304 just like the syscall). 340 error, just like the syscall).
341
342 "aio_read" will, like "sysread", shrink or grow the $data scalar to
343 offset plus the actual number of bytes read.
305 344
306 If $offset is undefined, then the current file descriptor offset 345 If $offset is undefined, then the current file descriptor offset
307 will be used (and updated), otherwise the file descriptor offset 346 will be used (and updated), otherwise the file descriptor offset
308 will not be changed by these calls. 347 will not be changed by these calls.
309 348
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330 reading at byte offset $in_offset, and starts writing at the current 369 reading at byte offset $in_offset, and starts writing at the current
331 file offset of $out_fh. Because of that, it is not safe to issue 370 file offset of $out_fh. Because of that, it is not safe to issue
332 more than one "aio_sendfile" per $out_fh, as they will interfere 371 more than one "aio_sendfile" per $out_fh, as they will interfere
333 with each other. 372 with each other.
334 373
374 Please note that "aio_sendfile" can read more bytes from $in_fh than
375 are written, and there is no way to find out how many bytes have
376 been read from "aio_sendfile" alone, as "aio_sendfile" only provides
377 the number of bytes written to $out_fh. Only if the result value
378 equals $length one can assume that $length bytes have been read.
379
380 Unlike with other "aio_" functions, it makes a lot of sense to use
381 "aio_sendfile" on non-blocking sockets, as long as one end
382 (typically the $in_fh) is a file - the file I/O will then be
383 asynchronous, while the socket I/O will be non-blocking. Note,
384 however, that you can run into a trap where "aio_sendfile" reads
385 some data with readahead, then fails to write all data, and when the
386 socket is ready the next time, the data in the cache is already
387 lost, forcing "aio_sendfile" to again hit the disk. Explicit
388 "aio_read" + "aio_write" let's you control resource usage much
389 better.
390
335 This call tries to make use of a native "sendfile" syscall to 391 This call tries to make use of a native "sendfile" syscall to
336 provide zero-copy operation. For this to work, $out_fh should refer 392 provide zero-copy operation. For this to work, $out_fh should refer
337 to a socket, and $in_fh should refer to mmap'able file. 393 to a socket, and $in_fh should refer to an mmap'able file.
338 394
339 If the native sendfile call fails or is not implemented, it will be 395 If a native sendfile cannot be found or it fails with "ENOSYS",
396 "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
340 emulated, so you can call "aio_sendfile" on any type of filehandle 397 it will be emulated, so you can call "aio_sendfile" on any type of
341 regardless of the limitations of the operating system. 398 filehandle regardless of the limitations of the operating system.
342
343 Please note, however, that "aio_sendfile" can read more bytes from
344 $in_fh than are written, and there is no way to find out how many
345 bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
346 only provides the number of bytes written to $out_fh. Only if the
347 result value equals $length one can assume that $length bytes have
348 been read.
349 399
350 aio_readahead $fh,$offset,$length, $callback->($retval) 400 aio_readahead $fh,$offset,$length, $callback->($retval)
351 "aio_readahead" populates the page cache with data from a file so 401 "aio_readahead" populates the page cache with data from a file so
352 that subsequent reads from that file will not block on disk I/O. The 402 that subsequent reads from that file will not block on disk I/O. The
353 $offset argument specifies the starting point from which data is to 403 $offset argument specifies the starting point from which data is to
… …
374 Currently, the stats are always 64-bit-stats, i.e. instead of 424 Currently, the stats are always 64-bit-stats, i.e. instead of
375 returning an error when stat'ing a large file, the results will be 425 returning an error when stat'ing a large file, the results will be
376 silently truncated unless perl itself is compiled with large file 426 silently truncated unless perl itself is compiled with large file
377 support. 427 support.
378 428
429 To help interpret the mode and dev/rdev stat values, IO::AIO offers
430 the following constants and functions (if not implemented, the
431 constants will be 0 and the functions will either "croak" or fall
432 back on traditional behaviour).
433
434 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
435 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
436 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
437
379 Example: Print the length of /etc/passwd: 438 Example: Print the length of /etc/passwd:
380 439
381 aio_stat "/etc/passwd", sub { 440 aio_stat "/etc/passwd", sub {
382 $_[0] and die "stat failed: $!"; 441 $_[0] and die "stat failed: $!";
383 print "size is ", -s _, "\n"; 442 print "size is ", -s _, "\n";
384 }; 443 };
385 444
445 aio_statvfs $fh_or_path, $callback->($statvfs)
446 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
447 whether a file handle or path was passed.
448
449 On success, the callback is passed a hash reference with the
450 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
451 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
452 failure, "undef" is passed.
453
454 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
455 and "ST_NOSUID".
456
457 The following non-POSIX IO::AIO::ST_* flag masks are defined to
458 their correct value when available, or to 0 on systems that do not
459 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
460 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
461 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
462
463 Example: stat "/wd" and dump out the data if successful.
464
465 aio_statvfs "/wd", sub {
466 my $f = $_[0]
467 or die "statvfs: $!";
468
469 use Data::Dumper;
470 say Dumper $f;
471 };
472
473 # result:
474 {
475 bsize => 1024,
476 bfree => 4333064312,
477 blocks => 10253828096,
478 files => 2050765568,
479 flag => 4096,
480 favail => 2042092649,
481 bavail => 4333064312,
482 ffree => 2042092649,
483 namemax => 255,
484 frsize => 1024,
485 fsid => 1810
486 }
487
386 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 488 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
387 Works like perl's "utime" function (including the special case of 489 Works like perl's "utime" function (including the special case of
388 $atime and $mtime being undef). Fractional times are supported if 490 $atime and $mtime being undef). Fractional times are supported if
389 the underlying syscalls support them. 491 the underlying syscalls support them.
390 492
… …
428 530
429 The only (POSIX-) portable way of calling this function is: 531 The only (POSIX-) portable way of calling this function is:
430 532
431 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 533 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
432 534
535 See "aio_stat" for info about some potentially helpful extra
536 constants and functions.
537
433 aio_link $srcpath, $dstpath, $callback->($status) 538 aio_link $srcpath, $dstpath, $callback->($status)
434 Asynchronously create a new link to the existing object at $srcpath 539 Asynchronously create a new link to the existing object at $srcpath
435 at the path $dstpath and call the callback with the result code. 540 at the path $dstpath and call the callback with the result code.
436 541
437 aio_symlink $srcpath, $dstpath, $callback->($status) 542 aio_symlink $srcpath, $dstpath, $callback->($status)
… …
460 aio_readdir $pathname, $callback->($entries) 565 aio_readdir $pathname, $callback->($entries)
461 Unlike the POSIX call of the same name, "aio_readdir" reads an 566 Unlike the POSIX call of the same name, "aio_readdir" reads an
462 entire directory (i.e. opendir + readdir + closedir). The entries 567 entire directory (i.e. opendir + readdir + closedir). The entries
463 will not be sorted, and will NOT include the "." and ".." entries. 568 will not be sorted, and will NOT include the "." and ".." entries.
464 569
465 The callback a single argument which is either "undef" or an 570 The callback is passed a single argument which is either "undef" or
466 array-ref with the filenames. 571 an array-ref with the filenames.
572
573 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
574 Quite similar to "aio_readdir", but the $flags argument allows to
575 tune behaviour and output format. In case of an error, $entries will
576 be "undef".
577
578 The flags are a combination of the following constants, ORed
579 together (the flags will also be passed to the callback, possibly
580 modified):
581
582 IO::AIO::READDIR_DENTS
583 When this flag is off, then the callback gets an arrayref
584 consisting of names only (as with "aio_readdir"), otherwise it
585 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
586 describing a single directory entry in more detail.
587
588 $name is the name of the entry.
589
590 $type is one of the "IO::AIO::DT_xxx" constants:
591
592 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
593 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
594 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
595
596 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
597 you need to know, you have to run stat yourself. Also, for speed
598 reasons, the $type scalars are read-only: you can not modify
599 them.
600
601 $inode is the inode number (which might not be exact on systems
602 with 64 bit inode numbers and 32 bit perls). This field has
603 unspecified content on systems that do not deliver the inode
604 information.
605
606 IO::AIO::READDIR_DIRS_FIRST
607 When this flag is set, then the names will be returned in an
608 order where likely directories come first, in optimal stat
609 order. This is useful when you need to quickly find directories,
610 or you want to find all directories while avoiding to stat()
611 each entry.
612
613 If the system returns type information in readdir, then this is
614 used to find directories directly. Otherwise, likely directories
615 are names beginning with ".", or otherwise names with no dots,
616 of which names with short names are tried first.
617
618 IO::AIO::READDIR_STAT_ORDER
619 When this flag is set, then the names will be returned in an
620 order suitable for stat()'ing each one. That is, when you plan
621 to stat() all files in the given directory, then the returned
622 order will likely be fastest.
623
624 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
625 specified, then the likely dirs come first, resulting in a less
626 optimal stat order.
627
628 IO::AIO::READDIR_FOUND_UNKNOWN
629 This flag should not be set when calling "aio_readdirx".
630 Instead, it is being set by "aio_readdirx", when any of the
631 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this
632 flag therefore indicates that all $type's are known, which can
633 be used to speed up some algorithms.
467 634
468 aio_load $path, $data, $callback->($status) 635 aio_load $path, $data, $callback->($status)
469 This is a composite request that tries to fully load the given file 636 This is a composite request that tries to fully load the given file
470 into memory. Status is the same as with aio_read. 637 into memory. Status is the same as with aio_read.
471 638
472 aio_copy $srcpath, $dstpath, $callback->($status) 639 aio_copy $srcpath, $dstpath, $callback->($status)
473 Try to copy the *file* (directories not supported as either source 640 Try to copy the *file* (directories not supported as either source
474 or destination) from $srcpath to $dstpath and call the callback with 641 or destination) from $srcpath to $dstpath and call the callback with
475 the 0 (error) or -1 ok. 642 a status of 0 (ok) or -1 (error, see $!).
476 643
477 This is a composite request that it creates the destination file 644 This is a composite request that creates the destination file with
478 with mode 0200 and copies the contents of the source file into it 645 mode 0200 and copies the contents of the source file into it using
479 using "aio_sendfile", followed by restoring atime, mtime, access 646 "aio_sendfile", followed by restoring atime, mtime, access mode and
480 mode and uid/gid, in that order. 647 uid/gid, in that order.
481 648
482 If an error occurs, the partial destination file will be unlinked, 649 If an error occurs, the partial destination file will be unlinked,
483 if possible, except when setting atime, mtime, access mode and 650 if possible, except when setting atime, mtime, access mode and
484 uid/gid, where errors are being ignored. 651 uid/gid, where errors are being ignored.
485 652
486 aio_move $srcpath, $dstpath, $callback->($status) 653 aio_move $srcpath, $dstpath, $callback->($status)
487 Try to move the *file* (directories not supported as either source 654 Try to move the *file* (directories not supported as either source
488 or destination) from $srcpath to $dstpath and call the callback with 655 or destination) from $srcpath to $dstpath and call the callback with
489 the 0 (error) or -1 ok. 656 a status of 0 (ok) or -1 (error, see $!).
490 657
491 This is a composite request that tries to rename(2) the file first. 658 This is a composite request that tries to rename(2) the file first;
492 If rename files with "EXDEV", it copies the file with "aio_copy" 659 if rename fails with "EXDEV", it copies the file with "aio_copy"
493 and, if that is successful, unlinking the $srcpath. 660 and, if that is successful, unlinks the $srcpath.
494 661
495 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 662 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
496 Scans a directory (similar to "aio_readdir") but additionally tries 663 Scans a directory (similar to "aio_readdir") but additionally tries
497 to efficiently separate the entries of directory $path into two sets 664 to efficiently separate the entries of directory $path into two sets
498 of names, directories you can recurse into (directories), and ones 665 of names, directories you can recurse into (directories), and ones
… …
518 Implementation notes. 685 Implementation notes.
519 686
520 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry 687 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
521 can. 688 can.
522 689
690 If readdir returns file type information, then this is used directly
691 to find directories.
692
523 After reading the directory, the modification time, size etc. of the 693 Otherwise, after reading the directory, the modification time, size
524 directory before and after the readdir is checked, and if they match 694 etc. of the directory before and after the readdir is checked, and
525 (and isn't the current time), the link count will be used to decide 695 if they match (and isn't the current time), the link count will be
526 how many entries are directories (if >= 2). Otherwise, no knowledge 696 used to decide how many entries are directories (if >= 2).
527 of the number of subdirectories will be assumed. 697 Otherwise, no knowledge of the number of subdirectories will be
698 assumed.
528 699
529 Then entries will be sorted into likely directories (everything 700 Then entries will be sorted into likely directories a non-initial
530 without a non-initial dot currently) and likely non-directories 701 dot currently) and likely non-directories (see "aio_readdirx"). Then
531 (everything else). Then every entry plus an appended "/." will be 702 every entry plus an appended "/." will be "stat"'ed, likely
532 "stat"'ed, likely directories first. If that succeeds, it assumes 703 directories first, in order of their inode numbers. If that
533 that the entry is a directory or a symlink to directory (which will 704 succeeds, it assumes that the entry is a directory or a symlink to
534 be checked seperately). This is often faster than stat'ing the entry 705 directory (which will be checked seperately). This is often faster
535 itself because filesystems might detect the type of the entry 706 than stat'ing the entry itself because filesystems might detect the
536 without reading the inode data (e.g. ext2fs filetype feature). 707 type of the entry without reading the inode data (e.g. ext2fs
708 filetype feature), even on systems that cannot return the filetype
709 information on readdir.
537 710
538 If the known number of directories (link count - 2) has been 711 If the known number of directories (link count - 2) has been
539 reached, the rest of the entries is assumed to be non-directories. 712 reached, the rest of the entries is assumed to be non-directories.
540 713
541 This only works with certainty on POSIX (= UNIX) filesystems, which 714 This only works with certainty on POSIX (= UNIX) filesystems, which
… …
563 callback with the fdatasync result code. 736 callback with the fdatasync result code.
564 737
565 If this call isn't available because your OS lacks it or it couldn't 738 If this call isn't available because your OS lacks it or it couldn't
566 be detected, it will be emulated by calling "fsync" instead. 739 be detected, it will be emulated by calling "fsync" instead.
567 740
741 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
742 Sync the data portion of the file specified by $offset and $length
743 to disk (but NOT the metadata), by calling the Linux-specific
744 sync_file_range call. If sync_file_range is not available or it
745 returns ENOSYS, then fdatasync or fsync is being substituted.
746
747 $flags can be a combination of
748 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
749 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
750 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
751 manpage for details.
752
568 aio_pathsync $path, $callback->($status) 753 aio_pathsync $path, $callback->($status)
569 This request tries to open, fsync and close the given path. This is 754 This request tries to open, fsync and close the given path. This is
570 a composite request intended tosync directories after directory 755 a composite request intended to sync directories after directory
571 operations (E.g. rename). This might not work on all operating 756 operations (E.g. rename). This might not work on all operating
572 systems or have any specific effect, but usually it makes sure that 757 systems or have any specific effect, but usually it makes sure that
573 directory changes get written to disc. It works for anything that 758 directory changes get written to disc. It works for anything that
574 can be opened for read-only, not just directories. 759 can be opened for read-only, not just directories.
575 760
761 Future versions of this function might fall back to other methods
762 when "fsync" on the directory fails (such as calling "sync").
763
576 Passes 0 when everything went ok, and -1 on error. 764 Passes 0 when everything went ok, and -1 on error.
765
766 aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
767 $callback->($status)
768 This is a rather advanced IO::AIO call, which only works on
769 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
770 also works on data scalars managed by the Sys::Mmap or Mmap modules,
771 note that the scalar must only be modified in-place while an aio
772 operation is pending on it).
773
774 It calls the "msync" function of your OS, if available, with the
775 memory area starting at $offset in the string and ending $length
776 bytes later. If $length is negative, counts from the end, and if
777 $length is "undef", then it goes till the end of the string. The
778 flags can be a combination of "IO::AIO::MS_ASYNC",
779 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
780
781 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
782 $callback->($status)
783 This is a rather advanced IO::AIO call, which works best on
784 mmap(2)ed scalars.
785
786 It touches (reads or writes) all memory pages in the specified range
787 inside the scalar. All caveats and parameters are the same as for
788 "aio_msync", above, except for flags, which must be either 0 (which
789 reads all pages and ensures they are instantiated) or
790 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
791 and writing an octet from it, which dirties the page).
792
793 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
794 This is a rather advanced IO::AIO call, which works best on
795 mmap(2)ed scalars.
796
797 It reads in all the pages of the underlying storage into memory (if
798 any) and locks them, so they are not getting swapped/paged out or
799 removed.
800
801 If $length is undefined, then the scalar will be locked till the
802 end.
803
804 On systems that do not implement "mlock", this function returns -1
805 and sets errno to "ENOSYS".
806
807 Note that the corresponding "munlock" is synchronous and is
808 documented under "MISCELLANEOUS FUNCTIONS".
809
810 Example: open a file, mmap and mlock it - both will be undone when
811 $data gets destroyed.
812
813 open my $fh, "<", $path or die "$path: $!";
814 my $data;
815 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
816 aio_mlock $data; # mlock in background
817
818 aio_mlockall $flags, $callback->($status)
819 Calls the "mlockall" function with the given $flags (a combination
820 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
821
822 On systems that do not implement "mlockall", this function returns
823 -1 and sets errno to "ENOSYS".
824
825 Note that the corresponding "munlockall" is synchronous and is
826 documented under "MISCELLANEOUS FUNCTIONS".
827
828 Example: asynchronously lock all current and future pages into
829 memory.
830
831 aio_mlockall IO::AIO::MCL_FUTURE;
577 832
578 aio_group $callback->(...) 833 aio_group $callback->(...)
579 This is a very special aio request: Instead of doing something, it 834 This is a very special aio request: Instead of doing something, it
580 is a container for other aio requests, which is useful if you want 835 is a container for other aio requests, which is useful if you want
581 to bundle many requests into a single, composite, request with a 836 to bundle many requests into a single, composite, request with a
… …
624 879
625 cancel $req 880 cancel $req
626 Cancels the request, if possible. Has the effect of skipping 881 Cancels the request, if possible. Has the effect of skipping
627 execution when entering the execute state and skipping calling the 882 execution when entering the execute state and skipping calling the
628 callback when entering the the result state, but will leave the 883 callback when entering the the result state, but will leave the
629 request otherwise untouched. That means that requests that currently 884 request otherwise untouched (with the exception of readdir). That
630 execute will not be stopped and resources held by the request will 885 means that requests that currently execute will not be stopped and
631 not be freed prematurely. 886 resources held by the request will not be freed prematurely.
632 887
633 cb $req $callback->(...) 888 cb $req $callback->(...)
634 Replace (or simply set) the callback registered to the request. 889 Replace (or simply set) the callback registered to the request.
635 890
636 IO::AIO::GRP CLASS 891 IO::AIO::GRP CLASS
… …
679 Their lifetime, simplified, looks like this: when they are empty, they 934 Their lifetime, simplified, looks like this: when they are empty, they
680 will finish very quickly. If they contain only requests that are in the 935 will finish very quickly. If they contain only requests that are in the
681 "done" state, they will also finish. Otherwise they will continue to 936 "done" state, they will also finish. Otherwise they will continue to
682 exist. 937 exist.
683 938
684 That means after creating a group you have some time to add requests. 939 That means after creating a group you have some time to add requests
685 And in the callbacks of those requests, you can add further requests to 940 (precisely before the callback has been invoked, which is only done
686 the group. And only when all those requests have finished will the the 941 within the "poll_cb"). And in the callbacks of those requests, you can
687 group itself finish. 942 add further requests to the group. And only when all those requests have
943 finished will the the group itself finish.
688 944
689 add $grp ... 945 add $grp ...
690 $grp->add (...) 946 $grp->add (...)
691 Add one or more requests to the group. Any type of IO::AIO::REQ can 947 Add one or more requests to the group. Any type of IO::AIO::REQ can
692 be added, including other groups, as long as you do not create 948 be added, including other groups, as long as you do not create
… …
696 952
697 $grp->cancel_subs 953 $grp->cancel_subs
698 Cancel all subrequests and clears any feeder, but not the group 954 Cancel all subrequests and clears any feeder, but not the group
699 request itself. Useful when you queued a lot of events but got a 955 request itself. Useful when you queued a lot of events but got a
700 result early. 956 result early.
957
958 The group request will finish normally (you cannot add requests to
959 the group).
701 960
702 $grp->result (...) 961 $grp->result (...)
703 Set the result value(s) that will be passed to the group callback 962 Set the result value(s) that will be passed to the group callback
704 when all subrequests have finished and set the groups errno to the 963 when all subrequests have finished and set the groups errno to the
705 current value of errno (just like calling "errno" without an error 964 current value of errno (just like calling "errno" without an error
… …
735 does not impose any limits). 994 does not impose any limits).
736 995
737 If the feed does not queue more requests when called, it will be 996 If the feed does not queue more requests when called, it will be
738 automatically removed from the group. 997 automatically removed from the group.
739 998
740 If the feed limit is 0, it will be set to 2 automatically. 999 If the feed limit is 0 when this method is called, it will be set to
1000 2 automatically.
741 1001
742 Example: 1002 Example:
743 1003
744 # stat all files in @files, but only ever use four aio requests concurrently: 1004 # stat all files in @files, but only ever use four aio requests concurrently:
745 1005
… …
756 Sets the feeder limit for the group: The feeder will be called 1016 Sets the feeder limit for the group: The feeder will be called
757 whenever the group contains less than this many requests. 1017 whenever the group contains less than this many requests.
758 1018
759 Setting the limit to 0 will pause the feeding process. 1019 Setting the limit to 0 will pause the feeding process.
760 1020
1021 The default value for the limit is 0, but note that setting a feeder
1022 automatically bumps it up to 2.
1023
761 SUPPORT FUNCTIONS 1024 SUPPORT FUNCTIONS
762 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1025 EVENT PROCESSING AND EVENT LOOP INTEGRATION
763 $fileno = IO::AIO::poll_fileno 1026 $fileno = IO::AIO::poll_fileno
764 Return the *request result pipe file descriptor*. This filehandle 1027 Return the *request result pipe file descriptor*. This filehandle
765 must be polled for reading by some mechanism outside this module 1028 must be polled for reading by some mechanism outside this module
766 (e.g. Event or select, see below or the SYNOPSIS). If the pipe 1029 (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
767 becomes readable you have to call "poll_cb" to check the results. 1030 pipe becomes readable you have to call "poll_cb" to check the
1031 results.
768 1032
769 See "poll_cb" for an example. 1033 See "poll_cb" for an example.
770 1034
771 IO::AIO::poll_cb 1035 IO::AIO::poll_cb
772 Process some outstanding events on the result pipe. You have to call 1036 Process some outstanding events on the result pipe. You have to call
773 this regularly. Returns the number of events processed. Returns 1037 this regularly. Returns 0 if all events could be processed (or there
774 immediately when no events are outstanding. The amount of events 1038 were no events to process), or -1 if it returned earlier for
775 processed depends on the settings of "IO::AIO::max_poll_req" and 1039 whatever reason. Returns immediately when no events are outstanding.
776 "IO::AIO::max_poll_time". 1040 The amount of events processed depends on the settings of
1041 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
777 1042
778 If not all requests were processed for whatever reason, the 1043 If not all requests were processed for whatever reason, the
779 filehandle will still be ready when "poll_cb" returns. 1044 filehandle will still be ready when "poll_cb" returns, so normally
1045 you don't have to do anything special to have it called later.
1046
1047 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1048 becomes ready, it can be beneficial to call this function from loops
1049 which submit a lot of requests, to make sure the results get
1050 processed when they become available and not just when the loop is
1051 finished and the event loop takes over again. This function returns
1052 very fast when there are no outstanding requests.
780 1053
781 Example: Install an Event watcher that automatically calls 1054 Example: Install an Event watcher that automatically calls
782 IO::AIO::poll_cb with high priority: 1055 IO::AIO::poll_cb with high priority (more examples can be found in
1056 the SYNOPSIS section, at the top of this document):
783 1057
784 Event->io (fd => IO::AIO::poll_fileno, 1058 Event->io (fd => IO::AIO::poll_fileno,
785 poll => 'r', async => 1, 1059 poll => 'r', async => 1,
786 cb => \&IO::AIO::poll_cb); 1060 cb => \&IO::AIO::poll_cb);
1061
1062 IO::AIO::poll_wait
1063 If there are any outstanding requests and none of them in the result
1064 phase, wait till the result filehandle becomes ready for reading
1065 (simply does a "select" on the filehandle. This is useful if you
1066 want to synchronously wait for some requests to finish).
1067
1068 See "nreqs" for an example.
1069
1070 IO::AIO::poll
1071 Waits until some requests have been handled.
1072
1073 Returns the number of requests processed, but is otherwise strictly
1074 equivalent to:
1075
1076 IO::AIO::poll_wait, IO::AIO::poll_cb
1077
1078 IO::AIO::flush
1079 Wait till all outstanding AIO requests have been handled.
1080
1081 Strictly equivalent to:
1082
1083 IO::AIO::poll_wait, IO::AIO::poll_cb
1084 while IO::AIO::nreqs;
787 1085
788 IO::AIO::max_poll_reqs $nreqs 1086 IO::AIO::max_poll_reqs $nreqs
789 IO::AIO::max_poll_time $seconds 1087 IO::AIO::max_poll_time $seconds
790 These set the maximum number of requests (default 0, meaning 1088 These set the maximum number of requests (default 0, meaning
791 infinity) that are being processed by "IO::AIO::poll_cb" in one 1089 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
815 # use a low priority so other tasks have priority 1113 # use a low priority so other tasks have priority
816 Event->io (fd => IO::AIO::poll_fileno, 1114 Event->io (fd => IO::AIO::poll_fileno,
817 poll => 'r', nice => 1, 1115 poll => 'r', nice => 1,
818 cb => &IO::AIO::poll_cb); 1116 cb => &IO::AIO::poll_cb);
819 1117
820 IO::AIO::poll_wait
821 If there are any outstanding requests and none of them in the result
822 phase, wait till the result filehandle becomes ready for reading
823 (simply does a "select" on the filehandle. This is useful if you
824 want to synchronously wait for some requests to finish).
825
826 See "nreqs" for an example.
827
828 IO::AIO::poll
829 Waits until some requests have been handled.
830
831 Returns the number of requests processed, but is otherwise strictly
832 equivalent to:
833
834 IO::AIO::poll_wait, IO::AIO::poll_cb
835
836 IO::AIO::flush
837 Wait till all outstanding AIO requests have been handled.
838
839 Strictly equivalent to:
840
841 IO::AIO::poll_wait, IO::AIO::poll_cb
842 while IO::AIO::nreqs;
843
844 CONTROLLING THE NUMBER OF THREADS 1118 CONTROLLING THE NUMBER OF THREADS
845 IO::AIO::min_parallel $nthreads 1119 IO::AIO::min_parallel $nthreads
846 Set the minimum number of AIO threads to $nthreads. The current 1120 Set the minimum number of AIO threads to $nthreads. The current
847 default is 8, which means eight asynchronous operations can execute 1121 default is 8, which means eight asynchronous operations can execute
848 concurrently at any one time (the number of outstanding requests, 1122 concurrently at any one time (the number of outstanding requests,
… …
877 1151
878 Under normal circumstances you don't need to call this function. 1152 Under normal circumstances you don't need to call this function.
879 1153
880 IO::AIO::max_idle $nthreads 1154 IO::AIO::max_idle $nthreads
881 Limit the number of threads (default: 4) that are allowed to idle 1155 Limit the number of threads (default: 4) that are allowed to idle
882 (i.e., threads that did not get a request to process within 10 1156 (i.e., threads that did not get a request to process within the idle
883 seconds). That means if a thread becomes idle while $nthreads other 1157 timeout (default: 10 seconds). That means if a thread becomes idle
884 threads are also idle, it will free its resources and exit. 1158 while $nthreads other threads are also idle, it will free its
1159 resources and exit.
885 1160
886 This is useful when you allow a large number of threads (e.g. 100 or 1161 This is useful when you allow a large number of threads (e.g. 100 or
887 1000) to allow for extremely high load situations, but want to free 1162 1000) to allow for extremely high load situations, but want to free
888 resources under normal circumstances (1000 threads can easily 1163 resources under normal circumstances (1000 threads can easily
889 consume 30MB of RAM). 1164 consume 30MB of RAM).
890 1165
891 The default is probably ok in most situations, especially if thread 1166 The default is probably ok in most situations, especially if thread
892 creation is fast. If thread creation is very slow on your system you 1167 creation is fast. If thread creation is very slow on your system you
893 might want to use larger values. 1168 might want to use larger values.
894 1169
1170 IO::AIO::idle_timeout $seconds
1171 Sets the minimum idle timeout (default 10) after which worker
1172 threads are allowed to exit. SEe "IO::AIO::max_idle".
1173
895 $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1174 IO::AIO::max_outstanding $maxreqs
896 This is a very bad function to use in interactive programs because 1175 This is a very bad function to use in interactive programs because
897 it blocks, and a bad way to reduce concurrency because it is 1176 it blocks, and a bad way to reduce concurrency because it is
898 inexact: Better use an "aio_group" together with a feed callback. 1177 inexact: Better use an "aio_group" together with a feed callback.
899 1178
900 Sets the maximum number of outstanding requests to $nreqs. If you do 1179 Sets the maximum number of outstanding requests to $nreqs. If you do
… …
904 1183
905 The default value is very large, so there is no practical limit on 1184 The default value is very large, so there is no practical limit on
906 the number of outstanding requests. 1185 the number of outstanding requests.
907 1186
908 You can still queue as many requests as you want. Therefore, 1187 You can still queue as many requests as you want. Therefore,
909 "max_oustsanding" is mainly useful in simple scripts (with low 1188 "max_outstanding" is mainly useful in simple scripts (with low
910 values) or as a stop gap to shield against fatal memory overflow 1189 values) or as a stop gap to shield against fatal memory overflow
911 (with large values). 1190 (with large values).
912 1191
913 STATISTICAL INFORMATION 1192 STATISTICAL INFORMATION
914 IO::AIO::nreqs 1193 IO::AIO::nreqs
… …
926 executed). 1205 executed).
927 1206
928 IO::AIO::npending 1207 IO::AIO::npending
929 Returns the number of requests currently in the pending state 1208 Returns the number of requests currently in the pending state
930 (executed, but not yet processed by poll_cb). 1209 (executed, but not yet processed by poll_cb).
1210
1211 MISCELLANEOUS FUNCTIONS
1212 IO::AIO implements some functions that might be useful, but are not
1213 asynchronous.
1214
1215 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1216 Calls the "eio_sendfile_sync" function, which is like
1217 "aio_sendfile", but is blocking (this makes most sense if you know
1218 the input data is likely cached already and the output filehandle is
1219 set to non-blocking operations).
1220
1221 Returns the number of bytes copied, or -1 on error.
1222
1223 IO::AIO::fadvise $fh, $offset, $len, $advice
1224 Simply calls the "posix_fadvise" function (see its manpage for
1225 details). The following advice constants are avaiable:
1226 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1227 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1228 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1229
1230 On systems that do not implement "posix_fadvise", this function
1231 returns ENOSYS, otherwise the return value of "posix_fadvise".
1232
1233 IO::AIO::madvise $scalar, $offset, $len, $advice
1234 Simply calls the "posix_madvise" function (see its manpage for
1235 details). The following advice constants are avaiable:
1236 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1237 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1238 "IO::AIO::MADV_DONTNEED".
1239
1240 On systems that do not implement "posix_madvise", this function
1241 returns ENOSYS, otherwise the return value of "posix_madvise".
1242
1243 IO::AIO::mprotect $scalar, $offset, $len, $protect
1244 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1245 $scalar (see its manpage for details). The following protect
1246 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1247 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1248
1249 On systems that do not implement "mprotect", this function returns
1250 ENOSYS, otherwise the return value of "mprotect".
1251
1252 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1253 Memory-maps a file (or anonymous memory range) and attaches it to
1254 the given $scalar, which will act like a string scalar.
1255
1256 The only operations allowed on the scalar are "substr"/"vec" that
1257 don't change the string length, and most read-only operations such
1258 as copying it or searching it with regexes and so on.
1259
1260 Anything else is unsafe and will, at best, result in memory leaks.
1261
1262 The memory map associated with the $scalar is automatically removed
1263 when the $scalar is destroyed, or when the "IO::AIO::mmap" or
1264 "IO::AIO::munmap" functions are called.
1265
1266 This calls the "mmap"(2) function internally. See your system's
1267 manual page for details on the $length, $prot and $flags parameters.
1268
1269 The $length must be larger than zero and smaller than the actual
1270 filesize.
1271
1272 $prot is a combination of "IO::AIO::PROT_NONE",
1273 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1274 "IO::AIO::PROT_WRITE",
1275
1276 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1277 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1278 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
1279 (which is set to "MAP_ANON" if your system only provides this
1280 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
1281 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
1282 "IO::AIO::MAP_NONBLOCK"
1283
1284 If $fh is "undef", then a file descriptor of -1 is passed.
1285
1286 $offset is the offset from the start of the file - it generally must
1287 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1288
1289 Example:
1290
1291 use Digest::MD5;
1292 use IO::AIO;
1293
1294 open my $fh, "<verybigfile"
1295 or die "$!";
1296
1297 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1298 or die "verybigfile: $!";
1299
1300 my $fast_md5 = md5 $data;
1301
1302 IO::AIO::munmap $scalar
1303 Removes a previous mmap and undefines the $scalar.
1304
1305 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1306 Calls the "munlock" function, undoing the effects of a previous
1307 "aio_mlock" call (see its description for details).
1308
1309 IO::AIO::munlockall
1310 Calls the "munlockall" function.
1311
1312 On systems that do not implement "munlockall", this function returns
1313 ENOSYS, otherwise the return value of "munlockall".
1314
1315EVENT LOOP INTEGRATION
1316 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1317 automatically into many event loops:
1318
1319 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1320 use AnyEvent::AIO;
1321
1322 You can also integrate IO::AIO manually into many event loops, here are
1323 some examples of how to do this:
1324
1325 # EV integration
1326 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1327
1328 # Event integration
1329 Event->io (fd => IO::AIO::poll_fileno,
1330 poll => 'r',
1331 cb => \&IO::AIO::poll_cb);
1332
1333 # Glib/Gtk2 integration
1334 add_watch Glib::IO IO::AIO::poll_fileno,
1335 in => sub { IO::AIO::poll_cb; 1 };
1336
1337 # Tk integration
1338 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1339 readable => \&IO::AIO::poll_cb);
1340
1341 # Danga::Socket integration
1342 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1343 \&IO::AIO::poll_cb);
931 1344
932 FORK BEHAVIOUR 1345 FORK BEHAVIOUR
933 This module should do "the right thing" when the process using it forks: 1346 This module should do "the right thing" when the process using it forks:
934 1347
935 Before the fork, IO::AIO enters a quiescent state where no requests can 1348 Before the fork, IO::AIO enters a quiescent state where no requests can
… …
964 1377
965KNOWN BUGS 1378KNOWN BUGS
966 Known bugs will be fixed in the next release. 1379 Known bugs will be fixed in the next release.
967 1380
968SEE ALSO 1381SEE ALSO
969 Coro::AIO. 1382 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1383 more natural syntax.
970 1384
971AUTHOR 1385AUTHOR
972 Marc Lehmann <schmorp@schmorp.de> 1386 Marc Lehmann <schmorp@schmorp.de>
973 http://home.schmorp.de/ 1387 http://home.schmorp.de/
974 1388

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