ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/README
(Generate patch)

Comparing IO-AIO/README (file contents):
Revision 1.39 by root, Wed Aug 5 11:53:16 2009 UTC vs.
Revision 1.49 by root, Mon Jul 18 03:09:06 2011 UTC

… …
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
… …
23 my $req = aio_unlink "/tmp/file", sub { }; 23 my $req = aio_unlink "/tmp/file", sub { };
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
29 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30 use AnyEvent::AIO;
31
32 # EV integration
33 my $aio_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 28
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. It is implemented as an interface to "libeio" 31 operating system supports. It is implemented as an interface to "libeio"
55 (<http://software.schmorp.de/pkg/libeio.html>). 32 (<http://software.schmorp.de/pkg/libeio.html>).
… …
95 72
96 # register the IO::AIO callback with EV 73 # register the IO::AIO callback with EV
97 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 74 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98 75
99 # queue the request to open /etc/passwd 76 # queue the request to open /etc/passwd
100 aio_open "/etc/passwd", O_RDONLY, 0, sub { 77 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101 my $fh = shift 78 my $fh = shift
102 or die "error while opening: $!"; 79 or die "error while opening: $!";
103 80
104 # stat'ing filehandles is generally non-blocking 81 # stat'ing filehandles is generally non-blocking
105 my $size = -s $fh; 82 my $size = -s $fh;
… …
168 anymore (except possibly for the Perl object, but its connection to 145 anymore (except possibly for the Perl object, but its connection to
169 the actual aio request is severed and calling its methods will 146 the actual aio request is severed and calling its methods will
170 either do nothing or result in a runtime error). 147 either do nothing or result in a runtime error).
171 148
172FUNCTIONS 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_realpath $path, $callback->($link)
174 aio_rename $srcpath, $dstpath, $callback->($status)
175 aio_mkdir $pathname, $mode, $callback->($status)
176 aio_rmdir $pathname, $callback->($status)
177 aio_readdir $pathname, $callback->($entries)
178 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
179 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
180 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
181 aio_load $path, $data, $callback->($status)
182 aio_copy $srcpath, $dstpath, $callback->($status)
183 aio_move $srcpath, $dstpath, $callback->($status)
184 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
185 aio_rmtree $path, $callback->($status)
186 aio_sync $callback->($status)
187 aio_fsync $fh, $callback->($status)
188 aio_fdatasync $fh, $callback->($status)
189 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
190 aio_pathsync $path, $callback->($status)
191 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
192 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
193 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
194 aio_mlockall $flags, $callback->($status)
195 aio_group $callback->(...)
196 aio_nop $callback->()
197
198 $prev_pri = aioreq_pri [$pri]
199 aioreq_nice $pri_adjust
200
201 IO::AIO::poll_wait
202 IO::AIO::poll_cb
203 IO::AIO::poll
204 IO::AIO::flush
205 IO::AIO::max_poll_reqs $nreqs
206 IO::AIO::max_poll_time $seconds
207 IO::AIO::min_parallel $nthreads
208 IO::AIO::max_parallel $nthreads
209 IO::AIO::max_idle $nthreads
210 IO::AIO::idle_timeout $seconds
211 IO::AIO::max_outstanding $maxreqs
212 IO::AIO::nreqs
213 IO::AIO::nready
214 IO::AIO::npending
215
216 IO::AIO::sendfile $ofh, $ifh, $offset, $count
217 IO::AIO::fadvise $fh, $offset, $len, $advice
218 IO::AIO::madvise $scalar, $offset, $length, $advice
219 IO::AIO::mprotect $scalar, $offset, $length, $protect
220 IO::AIO::munlock $scalar, $offset = 0, $length = undef
221 IO::AIO::munlockall
222
173 AIO REQUEST FUNCTIONS 223 AIO REQUEST FUNCTIONS
174 All the "aio_*" calls are more or less thin wrappers around the syscall 224 All the "aio_*" calls are more or less thin wrappers around the syscall
175 with the same name (sans "aio_"). The arguments are similar or 225 with the same name (sans "aio_"). The arguments are similar or
176 identical, and they all accept an additional (and optional) $callback 226 identical, and they all accept an additional (and optional) $callback
177 argument which must be a code reference. This code reference will get 227 argument which must be a code reference. This code reference will get
… …
248 will be modified by the umask in effect then the request is being 298 will be modified by the umask in effect then the request is being
249 executed, so better never change the umask. 299 executed, so better never change the umask.
250 300
251 Example: 301 Example:
252 302
253 aio_open "/etc/passwd", O_RDONLY, 0, sub { 303 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254 if ($_[0]) { 304 if ($_[0]) {
255 print "open successful, fh is $_[0]\n"; 305 print "open successful, fh is $_[0]\n";
256 ... 306 ...
257 } else { 307 } else {
258 die "open failed: $!\n"; 308 die "open failed: $!\n";
259 } 309 }
260 }; 310 };
261 311
312 In addition to all the common open modes/flags ("O_RDONLY",
313 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
314 "O_APPEND"), the following POSIX and non-POSIX constants are
315 available (missing ones on your system are, as usual, 0):
316
317 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
318 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
319 "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
320
262 aio_close $fh, $callback->($status) 321 aio_close $fh, $callback->($status)
263 Asynchronously close a file and call the callback with the result 322 Asynchronously close a file and call the callback with the result
264 code. 323 code.
265 324
266 Unfortunately, you can't do this to perl. Perl *insists* very 325 Unfortunately, you can't do this to perl. Perl *insists* very
… …
309 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 368 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
310 Tries to copy $length bytes from $in_fh to $out_fh. It starts 369 Tries to copy $length bytes from $in_fh to $out_fh. It starts
311 reading at byte offset $in_offset, and starts writing at the current 370 reading at byte offset $in_offset, and starts writing at the current
312 file offset of $out_fh. Because of that, it is not safe to issue 371 file offset of $out_fh. Because of that, it is not safe to issue
313 more than one "aio_sendfile" per $out_fh, as they will interfere 372 more than one "aio_sendfile" per $out_fh, as they will interfere
314 with each other. 373 with each other. The same $in_fh works fine though, as this function
374 does not move or use the file offset of $in_fh.
315 375
376 Please note that "aio_sendfile" can read more bytes from $in_fh than
377 are written, and there is no way to find out how many more bytes
378 have been read from "aio_sendfile" alone, as "aio_sendfile" only
379 provides the number of bytes written to $out_fh. Only if the result
380 value equals $length one can assume that $length bytes have been
381 read.
382
383 Unlike with other "aio_" functions, it makes a lot of sense to use
384 "aio_sendfile" on non-blocking sockets, as long as one end
385 (typically the $in_fh) is a file - the file I/O will then be
386 asynchronous, while the socket I/O will be non-blocking. Note,
387 however, that you can run into a trap where "aio_sendfile" reads
388 some data with readahead, then fails to write all data, and when the
389 socket is ready the next time, the data in the cache is already
390 lost, forcing "aio_sendfile" to again hit the disk. Explicit
391 "aio_read" + "aio_write" let's you better control resource usage.
392
316 This call tries to make use of a native "sendfile" syscall to 393 This call tries to make use of a native "sendfile"-like syscall to
317 provide zero-copy operation. For this to work, $out_fh should refer 394 provide zero-copy operation. For this to work, $out_fh should refer
318 to a socket, and $in_fh should refer to mmap'able file. 395 to a socket, and $in_fh should refer to an mmap'able file.
319 396
320 If the native sendfile call fails or is not implemented, it will be 397 If a native sendfile cannot be found or it fails with "ENOSYS",
321 emulated, so you can call "aio_sendfile" on any type of filehandle 398 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322 regardless of the limitations of the operating system. 399 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
400 any type of filehandle regardless of the limitations of the
401 operating system.
323 402
324 Please note, however, that "aio_sendfile" can read more bytes from 403 As native sendfile syscalls (as practically any non-POSIX interface
325 $in_fh than are written, and there is no way to find out how many 404 hacked together in a hurry to improve benchmark numbers) tend to be
326 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 405 rather buggy on many systems, this implementation tries to work
327 only provides the number of bytes written to $out_fh. Only if the 406 around some known bugs in Linux and FreeBSD kernels (probably
328 result value equals $length one can assume that $length bytes have 407 others, too), but that might fail, so you really really should check
329 been read. 408 the return value of "aio_sendfile" - fewre bytes than expected might
409 have been transferred.
330 410
331 aio_readahead $fh,$offset,$length, $callback->($retval) 411 aio_readahead $fh,$offset,$length, $callback->($retval)
332 "aio_readahead" populates the page cache with data from a file so 412 "aio_readahead" populates the page cache with data from a file so
333 that subsequent reads from that file will not block on disk I/O. The 413 that subsequent reads from that file will not block on disk I/O. The
334 $offset argument specifies the starting point from which data is to 414 $offset argument specifies the starting point from which data is to
… …
355 Currently, the stats are always 64-bit-stats, i.e. instead of 435 Currently, the stats are always 64-bit-stats, i.e. instead of
356 returning an error when stat'ing a large file, the results will be 436 returning an error when stat'ing a large file, the results will be
357 silently truncated unless perl itself is compiled with large file 437 silently truncated unless perl itself is compiled with large file
358 support. 438 support.
359 439
440 To help interpret the mode and dev/rdev stat values, IO::AIO offers
441 the following constants and functions (if not implemented, the
442 constants will be 0 and the functions will either "croak" or fall
443 back on traditional behaviour).
444
445 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
446 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
447 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
448
360 Example: Print the length of /etc/passwd: 449 Example: Print the length of /etc/passwd:
361 450
362 aio_stat "/etc/passwd", sub { 451 aio_stat "/etc/passwd", sub {
363 $_[0] and die "stat failed: $!"; 452 $_[0] and die "stat failed: $!";
364 print "size is ", -s _, "\n"; 453 print "size is ", -s _, "\n";
365 }; 454 };
366 455
456 aio_statvfs $fh_or_path, $callback->($statvfs)
457 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
458 whether a file handle or path was passed.
459
460 On success, the callback is passed a hash reference with the
461 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
462 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
463 failure, "undef" is passed.
464
465 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
466 and "ST_NOSUID".
467
468 The following non-POSIX IO::AIO::ST_* flag masks are defined to
469 their correct value when available, or to 0 on systems that do not
470 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
471 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
472 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
473
474 Example: stat "/wd" and dump out the data if successful.
475
476 aio_statvfs "/wd", sub {
477 my $f = $_[0]
478 or die "statvfs: $!";
479
480 use Data::Dumper;
481 say Dumper $f;
482 };
483
484 # result:
485 {
486 bsize => 1024,
487 bfree => 4333064312,
488 blocks => 10253828096,
489 files => 2050765568,
490 flag => 4096,
491 favail => 2042092649,
492 bavail => 4333064312,
493 ffree => 2042092649,
494 namemax => 255,
495 frsize => 1024,
496 fsid => 1810
497 }
498
367 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 499 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368 Works like perl's "utime" function (including the special case of 500 Works like perl's "utime" function (including the special case of
369 $atime and $mtime being undef). Fractional times are supported if 501 $atime and $mtime being undef). Fractional times are supported if
370 the underlying syscalls support them. 502 the underlying syscalls support them.
371 503
… …
409 541
410 The only (POSIX-) portable way of calling this function is: 542 The only (POSIX-) portable way of calling this function is:
411 543
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 544 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
413 545
546 See "aio_stat" for info about some potentially helpful extra
547 constants and functions.
548
414 aio_link $srcpath, $dstpath, $callback->($status) 549 aio_link $srcpath, $dstpath, $callback->($status)
415 Asynchronously create a new link to the existing object at $srcpath 550 Asynchronously create a new link to the existing object at $srcpath
416 at the path $dstpath and call the callback with the result code. 551 at the path $dstpath and call the callback with the result code.
417 552
418 aio_symlink $srcpath, $dstpath, $callback->($status) 553 aio_symlink $srcpath, $dstpath, $callback->($status)
… …
423 aio_readlink $path, $callback->($link) 558 aio_readlink $path, $callback->($link)
424 Asynchronously read the symlink specified by $path and pass it to 559 Asynchronously read the symlink specified by $path and pass it to
425 the callback. If an error occurs, nothing or undef gets passed to 560 the callback. If an error occurs, nothing or undef gets passed to
426 the callback. 561 the callback.
427 562
563 aio_realpath $path, $callback->($path)
564 Asynchronously make the path absolute and resolve any symlinks in
565 $path. The resulting path only consists of directories (Same as
566 Cwd::realpath).
567
568 This request can be used to get the absolute path of the current
569 working directory by passing it a path of . (a single dot).
570
428 aio_rename $srcpath, $dstpath, $callback->($status) 571 aio_rename $srcpath, $dstpath, $callback->($status)
429 Asynchronously rename the object at $srcpath to $dstpath, just as 572 Asynchronously rename the object at $srcpath to $dstpath, just as
430 rename(2) and call the callback with the result code. 573 rename(2) and call the callback with the result code.
431 574
432 aio_mkdir $pathname, $mode, $callback->($status) 575 aio_mkdir $pathname, $mode, $callback->($status)
… …
454 The flags are a combination of the following constants, ORed 597 The flags are a combination of the following constants, ORed
455 together (the flags will also be passed to the callback, possibly 598 together (the flags will also be passed to the callback, possibly
456 modified): 599 modified):
457 600
458 IO::AIO::READDIR_DENTS 601 IO::AIO::READDIR_DENTS
459 When this flag is off, then the callback gets an arrayref with 602 When this flag is off, then the callback gets an arrayref
460 of names only (as with "aio_readdir"), otherwise it gets an 603 consisting of names only (as with "aio_readdir"), otherwise it
461 arrayref with "[$name, $type, $inode]" arrayrefs, each 604 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462 describing a single directory entry in more detail. 605 describing a single directory entry in more detail.
463 606
464 $name is the name of the entry. 607 $name is the name of the entry.
465 608
466 $type is one of the "IO::AIO::DT_xxx" constants: 609 $type is one of the "IO::AIO::DT_xxx" constants:
… …
479 unspecified content on systems that do not deliver the inode 622 unspecified content on systems that do not deliver the inode
480 information. 623 information.
481 624
482 IO::AIO::READDIR_DIRS_FIRST 625 IO::AIO::READDIR_DIRS_FIRST
483 When this flag is set, then the names will be returned in an 626 When this flag is set, then the names will be returned in an
484 order where likely directories come first. This is useful when 627 order where likely directories come first, in optimal stat
485 you need to quickly find directories, or you want to find all 628 order. This is useful when you need to quickly find directories,
486 directories while avoiding to stat() each entry. 629 or you want to find all directories while avoiding to stat()
630 each entry.
487 631
488 If the system returns type information in readdir, then this is 632 If the system returns type information in readdir, then this is
489 used to find directories directly. Otherwise, likely directories 633 used to find directories directly. Otherwise, likely directories
490 are files beginning with ".", or otherwise files with no dots, 634 are names beginning with ".", or otherwise names with no dots,
491 of which files with short names are tried first. 635 of which names with short names are tried first.
492 636
493 IO::AIO::READDIR_STAT_ORDER 637 IO::AIO::READDIR_STAT_ORDER
494 When this flag is set, then the names will be returned in an 638 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 639 order suitable for stat()'ing each one. That is, when you plan
496 to stat() all files in the given directory, then the returned 640 to stat() all files in the given directory, then the returned
… …
512 into memory. Status is the same as with aio_read. 656 into memory. Status is the same as with aio_read.
513 657
514 aio_copy $srcpath, $dstpath, $callback->($status) 658 aio_copy $srcpath, $dstpath, $callback->($status)
515 Try to copy the *file* (directories not supported as either source 659 Try to copy the *file* (directories not supported as either source
516 or destination) from $srcpath to $dstpath and call the callback with 660 or destination) from $srcpath to $dstpath and call the callback with
517 the 0 (error) or -1 ok. 661 a status of 0 (ok) or -1 (error, see $!).
518 662
519 This is a composite request that creates the destination file with 663 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 664 mode 0200 and copies the contents of the source file into it using
521 "aio_sendfile", followed by restoring atime, mtime, access mode and 665 "aio_sendfile", followed by restoring atime, mtime, access mode and
522 uid/gid, in that order. 666 uid/gid, in that order.
… …
526 uid/gid, where errors are being ignored. 670 uid/gid, where errors are being ignored.
527 671
528 aio_move $srcpath, $dstpath, $callback->($status) 672 aio_move $srcpath, $dstpath, $callback->($status)
529 Try to move the *file* (directories not supported as either source 673 Try to move the *file* (directories not supported as either source
530 or destination) from $srcpath to $dstpath and call the callback with 674 or destination) from $srcpath to $dstpath and call the callback with
531 the 0 (error) or -1 ok. 675 a status of 0 (ok) or -1 (error, see $!).
532 676
533 This is a composite request that tries to rename(2) the file first; 677 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" 678 if rename fails with "EXDEV", it copies the file with "aio_copy"
535 and, if that is successful, unlinks the $srcpath. 679 and, if that is successful, unlinks the $srcpath.
536 680
… …
636 Future versions of this function might fall back to other methods 780 Future versions of this function might fall back to other methods
637 when "fsync" on the directory fails (such as calling "sync"). 781 when "fsync" on the directory fails (such as calling "sync").
638 782
639 Passes 0 when everything went ok, and -1 on error. 783 Passes 0 when everything went ok, and -1 on error.
640 784
785 aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
786 $callback->($status)
787 This is a rather advanced IO::AIO call, which only works on
788 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
789 also works on data scalars managed by the Sys::Mmap or Mmap modules,
790 note that the scalar must only be modified in-place while an aio
791 operation is pending on it).
792
793 It calls the "msync" function of your OS, if available, with the
794 memory area starting at $offset in the string and ending $length
795 bytes later. If $length is negative, counts from the end, and if
796 $length is "undef", then it goes till the end of the string. The
797 flags can be a combination of "IO::AIO::MS_ASYNC",
798 "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
799
800 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
801 $callback->($status)
802 This is a rather advanced IO::AIO call, which works best on
803 mmap(2)ed scalars.
804
805 It touches (reads or writes) all memory pages in the specified range
806 inside the scalar. All caveats and parameters are the same as for
807 "aio_msync", above, except for flags, which must be either 0 (which
808 reads all pages and ensures they are instantiated) or
809 "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
810 and writing an octet from it, which dirties the page).
811
812 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
813 This is a rather advanced IO::AIO call, which works best on
814 mmap(2)ed scalars.
815
816 It reads in all the pages of the underlying storage into memory (if
817 any) and locks them, so they are not getting swapped/paged out or
818 removed.
819
820 If $length is undefined, then the scalar will be locked till the
821 end.
822
823 On systems that do not implement "mlock", this function returns -1
824 and sets errno to "ENOSYS".
825
826 Note that the corresponding "munlock" is synchronous and is
827 documented under "MISCELLANEOUS FUNCTIONS".
828
829 Example: open a file, mmap and mlock it - both will be undone when
830 $data gets destroyed.
831
832 open my $fh, "<", $path or die "$path: $!";
833 my $data;
834 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
835 aio_mlock $data; # mlock in background
836
837 aio_mlockall $flags, $callback->($status)
838 Calls the "mlockall" function with the given $flags (a combination
839 of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
840
841 On systems that do not implement "mlockall", this function returns
842 -1 and sets errno to "ENOSYS".
843
844 Note that the corresponding "munlockall" is synchronous and is
845 documented under "MISCELLANEOUS FUNCTIONS".
846
847 Example: asynchronously lock all current and future pages into
848 memory.
849
850 aio_mlockall IO::AIO::MCL_FUTURE;
851
641 aio_group $callback->(...) 852 aio_group $callback->(...)
642 This is a very special aio request: Instead of doing something, it 853 This is a very special aio request: Instead of doing something, it
643 is a container for other aio requests, which is useful if you want 854 is a container for other aio requests, which is useful if you want
644 to bundle many requests into a single, composite, request with a 855 to bundle many requests into a single, composite, request with a
645 definite callback and the ability to cancel the whole request with 856 definite callback and the ability to cancel the whole request with
… …
760 971
761 $grp->cancel_subs 972 $grp->cancel_subs
762 Cancel all subrequests and clears any feeder, but not the group 973 Cancel all subrequests and clears any feeder, but not the group
763 request itself. Useful when you queued a lot of events but got a 974 request itself. Useful when you queued a lot of events but got a
764 result early. 975 result early.
976
977 The group request will finish normally (you cannot add requests to
978 the group).
765 979
766 $grp->result (...) 980 $grp->result (...)
767 Set the result value(s) that will be passed to the group callback 981 Set the result value(s) that will be passed to the group callback
768 when all subrequests have finished and set the groups errno to the 982 when all subrequests have finished and set the groups errno to the
769 current value of errno (just like calling "errno" without an error 983 current value of errno (just like calling "errno" without an error
… …
837 1051
838 See "poll_cb" for an example. 1052 See "poll_cb" for an example.
839 1053
840 IO::AIO::poll_cb 1054 IO::AIO::poll_cb
841 Process some outstanding events on the result pipe. You have to call 1055 Process some outstanding events on the result pipe. You have to call
842 this regularly. Returns 0 if all events could be processed, or -1 if 1056 this regularly. Returns 0 if all events could be processed (or there
843 it returned earlier for whatever reason. Returns immediately when no 1057 were no events to process), or -1 if it returned earlier for
844 events are outstanding. The amount of events processed depends on 1058 whatever reason. Returns immediately when no events are outstanding.
845 the settings of "IO::AIO::max_poll_req" and 1059 The amount of events processed depends on the settings of
846 "IO::AIO::max_poll_time". 1060 "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
847 1061
848 If not all requests were processed for whatever reason, the 1062 If not all requests were processed for whatever reason, the
849 filehandle will still be ready when "poll_cb" returns, so normally 1063 filehandle will still be ready when "poll_cb" returns, so normally
850 you don't have to do anything special to have it called later. 1064 you don't have to do anything special to have it called later.
851 1065
1066 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1067 becomes ready, it can be beneficial to call this function from loops
1068 which submit a lot of requests, to make sure the results get
1069 processed when they become available and not just when the loop is
1070 finished and the event loop takes over again. This function returns
1071 very fast when there are no outstanding requests.
1072
852 Example: Install an Event watcher that automatically calls 1073 Example: Install an Event watcher that automatically calls
853 IO::AIO::poll_cb with high priority (more examples can be found in 1074 IO::AIO::poll_cb with high priority (more examples can be found in
854 the SYNOPSIS section, at the top of this document): 1075 the SYNOPSIS section, at the top of this document):
855 1076
856 Event->io (fd => IO::AIO::poll_fileno, 1077 Event->io (fd => IO::AIO::poll_fileno,
857 poll => 'r', async => 1, 1078 poll => 'r', async => 1,
858 cb => \&IO::AIO::poll_cb); 1079 cb => \&IO::AIO::poll_cb);
1080
1081 IO::AIO::poll_wait
1082 If there are any outstanding requests and none of them in the result
1083 phase, wait till the result filehandle becomes ready for reading
1084 (simply does a "select" on the filehandle. This is useful if you
1085 want to synchronously wait for some requests to finish).
1086
1087 See "nreqs" for an example.
1088
1089 IO::AIO::poll
1090 Waits until some requests have been handled.
1091
1092 Returns the number of requests processed, but is otherwise strictly
1093 equivalent to:
1094
1095 IO::AIO::poll_wait, IO::AIO::poll_cb
1096
1097 IO::AIO::flush
1098 Wait till all outstanding AIO requests have been handled.
1099
1100 Strictly equivalent to:
1101
1102 IO::AIO::poll_wait, IO::AIO::poll_cb
1103 while IO::AIO::nreqs;
859 1104
860 IO::AIO::max_poll_reqs $nreqs 1105 IO::AIO::max_poll_reqs $nreqs
861 IO::AIO::max_poll_time $seconds 1106 IO::AIO::max_poll_time $seconds
862 These set the maximum number of requests (default 0, meaning 1107 These set the maximum number of requests (default 0, meaning
863 infinity) that are being processed by "IO::AIO::poll_cb" in one 1108 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
887 # use a low priority so other tasks have priority 1132 # use a low priority so other tasks have priority
888 Event->io (fd => IO::AIO::poll_fileno, 1133 Event->io (fd => IO::AIO::poll_fileno,
889 poll => 'r', nice => 1, 1134 poll => 'r', nice => 1,
890 cb => &IO::AIO::poll_cb); 1135 cb => &IO::AIO::poll_cb);
891 1136
892 IO::AIO::poll_wait
893 If there are any outstanding requests and none of them in the result
894 phase, wait till the result filehandle becomes ready for reading
895 (simply does a "select" on the filehandle. This is useful if you
896 want to synchronously wait for some requests to finish).
897
898 See "nreqs" for an example.
899
900 IO::AIO::poll
901 Waits until some requests have been handled.
902
903 Returns the number of requests processed, but is otherwise strictly
904 equivalent to:
905
906 IO::AIO::poll_wait, IO::AIO::poll_cb
907
908 IO::AIO::flush
909 Wait till all outstanding AIO requests have been handled.
910
911 Strictly equivalent to:
912
913 IO::AIO::poll_wait, IO::AIO::poll_cb
914 while IO::AIO::nreqs;
915
916 CONTROLLING THE NUMBER OF THREADS 1137 CONTROLLING THE NUMBER OF THREADS
917 IO::AIO::min_parallel $nthreads 1138 IO::AIO::min_parallel $nthreads
918 Set the minimum number of AIO threads to $nthreads. The current 1139 Set the minimum number of AIO threads to $nthreads. The current
919 default is 8, which means eight asynchronous operations can execute 1140 default is 8, which means eight asynchronous operations can execute
920 concurrently at any one time (the number of outstanding requests, 1141 concurrently at any one time (the number of outstanding requests,
… …
949 1170
950 Under normal circumstances you don't need to call this function. 1171 Under normal circumstances you don't need to call this function.
951 1172
952 IO::AIO::max_idle $nthreads 1173 IO::AIO::max_idle $nthreads
953 Limit the number of threads (default: 4) that are allowed to idle 1174 Limit the number of threads (default: 4) that are allowed to idle
954 (i.e., threads that did not get a request to process within 10 1175 (i.e., threads that did not get a request to process within the idle
955 seconds). That means if a thread becomes idle while $nthreads other 1176 timeout (default: 10 seconds). That means if a thread becomes idle
956 threads are also idle, it will free its resources and exit. 1177 while $nthreads other threads are also idle, it will free its
1178 resources and exit.
957 1179
958 This is useful when you allow a large number of threads (e.g. 100 or 1180 This is useful when you allow a large number of threads (e.g. 100 or
959 1000) to allow for extremely high load situations, but want to free 1181 1000) to allow for extremely high load situations, but want to free
960 resources under normal circumstances (1000 threads can easily 1182 resources under normal circumstances (1000 threads can easily
961 consume 30MB of RAM). 1183 consume 30MB of RAM).
962 1184
963 The default is probably ok in most situations, especially if thread 1185 The default is probably ok in most situations, especially if thread
964 creation is fast. If thread creation is very slow on your system you 1186 creation is fast. If thread creation is very slow on your system you
965 might want to use larger values. 1187 might want to use larger values.
966 1188
1189 IO::AIO::idle_timeout $seconds
1190 Sets the minimum idle timeout (default 10) after which worker
1191 threads are allowed to exit. SEe "IO::AIO::max_idle".
1192
967 IO::AIO::max_outstanding $maxreqs 1193 IO::AIO::max_outstanding $maxreqs
1194 Sets the maximum number of outstanding requests to $nreqs. If you do
1195 queue up more than this number of requests, the next call to
1196 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
1197 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1198 no longer exceeded.
1199
1200 In other words, this setting does not enforce a queue limit, but can
1201 be used to make poll functions block if the limit is exceeded.
1202
968 This is a very bad function to use in interactive programs because 1203 This is a very bad function to use in interactive programs because
969 it blocks, and a bad way to reduce concurrency because it is 1204 it blocks, and a bad way to reduce concurrency because it is
970 inexact: Better use an "aio_group" together with a feed callback. 1205 inexact: Better use an "aio_group" together with a feed callback.
971 1206
972 Sets the maximum number of outstanding requests to $nreqs. If you do 1207 It's main use is in scripts without an event loop - when you want to
973 queue up more than this number of requests, the next call to the 1208 stat a lot of files, you can write somehting like this:
974 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
975 function will block until the limit is no longer exceeded.
976 1209
977 The default value is very large, so there is no practical limit on 1210 IO::AIO::max_outstanding 32;
1211
1212 for my $path (...) {
1213 aio_stat $path , ...;
1214 IO::AIO::poll_cb;
1215 }
1216
1217 IO::AIO::flush;
1218
1219 The call to "poll_cb" inside the loop will normally return
1220 instantly, but as soon as more thna 32 reqeusts are in-flight, it
1221 will block until some requests have been handled. This keeps the
1222 loop from pushing a large number of "aio_stat" requests onto the
1223 queue.
1224
1225 The default value for "max_outstanding" is very large, so there is
978 the number of outstanding requests. 1226 no practical limit on the number of outstanding requests.
979
980 You can still queue as many requests as you want. Therefore,
981 "max_outstanding" is mainly useful in simple scripts (with low
982 values) or as a stop gap to shield against fatal memory overflow
983 (with large values).
984 1227
985 STATISTICAL INFORMATION 1228 STATISTICAL INFORMATION
986 IO::AIO::nreqs 1229 IO::AIO::nreqs
987 Returns the number of requests currently in the ready, execute or 1230 Returns the number of requests currently in the ready, execute or
988 pending states (i.e. for which their callback has not been invoked 1231 pending states (i.e. for which their callback has not been invoked
… …
1012 set to non-blocking operations). 1255 set to non-blocking operations).
1013 1256
1014 Returns the number of bytes copied, or -1 on error. 1257 Returns the number of bytes copied, or -1 on error.
1015 1258
1016 IO::AIO::fadvise $fh, $offset, $len, $advice 1259 IO::AIO::fadvise $fh, $offset, $len, $advice
1017 Simply calls the "posix_fadvise" function (see it's manpage for 1260 Simply calls the "posix_fadvise" function (see its manpage for
1018 details). The following advice constants are avaiable: 1261 details). The following advice constants are avaiable:
1019 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1262 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1263 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1264 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022 1265
1023 On systems that do not implement "posix_fadvise", this function 1266 On systems that do not implement "posix_fadvise", this function
1024 returns ENOSYS, otherwise the return value of "posix_fadvise". 1267 returns ENOSYS, otherwise the return value of "posix_fadvise".
1025 1268
1269 IO::AIO::madvise $scalar, $offset, $len, $advice
1270 Simply calls the "posix_madvise" function (see its manpage for
1271 details). The following advice constants are avaiable:
1272 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1273 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1274 "IO::AIO::MADV_DONTNEED".
1275
1276 On systems that do not implement "posix_madvise", this function
1277 returns ENOSYS, otherwise the return value of "posix_madvise".
1278
1279 IO::AIO::mprotect $scalar, $offset, $len, $protect
1280 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1281 $scalar (see its manpage for details). The following protect
1282 constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1283 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1284
1285 On systems that do not implement "mprotect", this function returns
1286 ENOSYS, otherwise the return value of "mprotect".
1287
1288 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1289 Memory-maps a file (or anonymous memory range) and attaches it to
1290 the given $scalar, which will act like a string scalar.
1291
1292 The only operations allowed on the scalar are "substr"/"vec" that
1293 don't change the string length, and most read-only operations such
1294 as copying it or searching it with regexes and so on.
1295
1296 Anything else is unsafe and will, at best, result in memory leaks.
1297
1298 The memory map associated with the $scalar is automatically removed
1299 when the $scalar is destroyed, or when the "IO::AIO::mmap" or
1300 "IO::AIO::munmap" functions are called.
1301
1302 This calls the "mmap"(2) function internally. See your system's
1303 manual page for details on the $length, $prot and $flags parameters.
1304
1305 The $length must be larger than zero and smaller than the actual
1306 filesize.
1307
1308 $prot is a combination of "IO::AIO::PROT_NONE",
1309 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1310 "IO::AIO::PROT_WRITE",
1311
1312 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1313 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1314 not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
1315 (which is set to "MAP_ANON" if your system only provides this
1316 constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
1317 "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
1318 "IO::AIO::MAP_NONBLOCK"
1319
1320 If $fh is "undef", then a file descriptor of -1 is passed.
1321
1322 $offset is the offset from the start of the file - it generally must
1323 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1324
1325 Example:
1326
1327 use Digest::MD5;
1328 use IO::AIO;
1329
1330 open my $fh, "<verybigfile"
1331 or die "$!";
1332
1333 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1334 or die "verybigfile: $!";
1335
1336 my $fast_md5 = md5 $data;
1337
1338 IO::AIO::munmap $scalar
1339 Removes a previous mmap and undefines the $scalar.
1340
1341 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1342 Calls the "munlock" function, undoing the effects of a previous
1343 "aio_mlock" call (see its description for details).
1344
1345 IO::AIO::munlockall
1346 Calls the "munlockall" function.
1347
1348 On systems that do not implement "munlockall", this function returns
1349 ENOSYS, otherwise the return value of "munlockall".
1350
1351EVENT LOOP INTEGRATION
1352 It is recommended to use AnyEvent::AIO to integrate IO::AIO
1353 automatically into many event loops:
1354
1355 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1356 use AnyEvent::AIO;
1357
1358 You can also integrate IO::AIO manually into many event loops, here are
1359 some examples of how to do this:
1360
1361 # EV integration
1362 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1363
1364 # Event integration
1365 Event->io (fd => IO::AIO::poll_fileno,
1366 poll => 'r',
1367 cb => \&IO::AIO::poll_cb);
1368
1369 # Glib/Gtk2 integration
1370 add_watch Glib::IO IO::AIO::poll_fileno,
1371 in => sub { IO::AIO::poll_cb; 1 };
1372
1373 # Tk integration
1374 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1375 readable => \&IO::AIO::poll_cb);
1376
1377 # Danga::Socket integration
1378 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1379 \&IO::AIO::poll_cb);
1380
1026 FORK BEHAVIOUR 1381 FORK BEHAVIOUR
1027 This module should do "the right thing" when the process using it forks: 1382 Usage of pthreads in a program changes the semantics of fork
1383 considerably. Specifically, only async-safe functions can be called
1384 after fork. Perl doesn't know about this, so in general, you cannot call
1385 fork with defined behaviour in perl if pthreads are involved. IO::AIO
1386 uses pthreads, so this applies, but many other extensions and (for
1387 inexplicable reasons) perl itself often is linked against pthreads, so
1388 this limitation applies to quite a lot of perls.
1028 1389
1029 Before the fork, IO::AIO enters a quiescent state where no requests can 1390 This module no longer tries to fight your OS, or POSIX. That means
1030 be added in other threads and no results will be processed. After the 1391 IO::AIO only works in the process that loaded it. Forking is fully
1031 fork the parent simply leaves the quiescent state and continues 1392 supported, but using IO::AIO in the child is not.
1032 request/result processing, while the child frees the request/result
1033 queue (so that the requests started before the fork will only be handled
1034 in the parent). Threads will be started on demand until the limit set in
1035 the parent process has been reached again.
1036 1393
1037 In short: the parent will, after a short pause, continue as if fork had 1394 You might get around by not *using* IO::AIO before (or after) forking.
1038 not been called, while the child will act as if IO::AIO has not been 1395 You could also try to call the IO::AIO::reinit function in the child:
1039 used yet. 1396
1397 IO::AIO::reinit
1398 Abondons all current requests and I/O threads and simply
1399 reinitialises all data structures. This is not an operation
1400 suppported by any standards, but happens to work on GNU/Linux and
1401 some newer BSD systems.
1402
1403 The only reasonable use for this function is to call it after
1404 forking, if "IO::AIO" was used in the parent. Calling it while
1405 IO::AIO is active in the process will result in undefined behaviour.
1406 Calling it at any time will also result in any undefined (by POSIX)
1407 behaviour.
1040 1408
1041 MEMORY USAGE 1409 MEMORY USAGE
1042 Per-request usage: 1410 Per-request usage:
1043 1411
1044 Each aio request uses - depending on your architecture - around 100-200 1412 Each aio request uses - depending on your architecture - around 100-200

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines