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Revision 1.152 by root, Fri Jun 12 16:48:08 2009 UTC vs.
Revision 1.208 by root, Mon Sep 26 20:19:08 2011 UTC

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4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
9 aio_open "/etc/passwd", O_RDONLY, 0, sub { 9 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10 my $fh = shift 10 my $fh = shift
11 or die "/etc/passwd: $!"; 11 or die "/etc/passwd: $!";
12 ... 12 ...
13 }; 13 };
14 14
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26 $req->cancel; # cancel request if still in queue 26 $req->cancel; # cancel request if still in queue
27 27
28 my $grp = aio_group sub { print "all stats done\n" }; 28 my $grp = aio_group sub { print "all stats done\n" };
29 add $grp aio_stat "..." for ...; 29 add $grp aio_stat "..." for ...;
30 30
31 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32 use AnyEvent::AIO;
33
34 # EV integration
35 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37 # Event integration
38 Event->io (fd => IO::AIO::poll_fileno,
39 poll => 'r',
40 cb => \&IO::AIO::poll_cb);
41
42 # Glib/Gtk2 integration
43 add_watch Glib::IO IO::AIO::poll_fileno,
44 in => sub { IO::AIO::poll_cb; 1 };
45
46 # Tk integration
47 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48 readable => \&IO::AIO::poll_cb);
49
50 # Danga::Socket integration
51 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52 \&IO::AIO::poll_cb);
53
54=head1 DESCRIPTION 31=head1 DESCRIPTION
55 32
56This module implements asynchronous I/O using whatever means your 33This module implements asynchronous I/O using whatever means your
57operating system supports. 34operating system supports. It is implemented as an interface to C<libeio>
35(L<http://software.schmorp.de/pkg/libeio.html>).
58 36
59Asynchronous means that operations that can normally block your program 37Asynchronous means that operations that can normally block your program
60(e.g. reading from disk) will be done asynchronously: the operation 38(e.g. reading from disk) will be done asynchronously: the operation
61will still block, but you can do something else in the meantime. This 39will still block, but you can do something else in the meantime. This
62is extremely useful for programs that need to stay interactive even 40is extremely useful for programs that need to stay interactive even
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66on a RAID volume or over NFS when you do a number of stat operations 44on a RAID volume or over NFS when you do a number of stat operations
67concurrently. 45concurrently.
68 46
69While most of this works on all types of file descriptors (for 47While most of this works on all types of file descriptors (for
70example sockets), using these functions on file descriptors that 48example sockets), using these functions on file descriptors that
71support nonblocking operation (again, sockets, pipes etc.) is very 49support nonblocking operation (again, sockets, pipes etc.) is
72inefficient. Use an event loop for that (such as the L<Event|Event> 50very inefficient. Use an event loop for that (such as the L<EV>
73module): IO::AIO will naturally fit into such an event loop itself. 51module): IO::AIO will naturally fit into such an event loop itself.
74 52
75In this version, a number of threads are started that execute your 53In this version, a number of threads are started that execute your
76requests and signal their completion. You don't need thread support 54requests and signal their completion. You don't need thread support
77in perl, and the threads created by this module will not be visible 55in perl, and the threads created by this module will not be visible
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87yourself, always call C<poll_cb> from within the same thread, or never 65yourself, always call C<poll_cb> from within the same thread, or never
88call C<poll_cb> (or other C<aio_> functions) recursively. 66call C<poll_cb> (or other C<aio_> functions) recursively.
89 67
90=head2 EXAMPLE 68=head2 EXAMPLE
91 69
92This is a simple example that uses the Event module and loads 70This is a simple example that uses the EV module and loads
93F</etc/passwd> asynchronously: 71F</etc/passwd> asynchronously:
94 72
95 use Fcntl; 73 use Fcntl;
96 use Event; 74 use EV;
97 use IO::AIO; 75 use IO::AIO;
98 76
99 # register the IO::AIO callback with Event 77 # register the IO::AIO callback with EV
100 Event->io (fd => IO::AIO::poll_fileno, 78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101 poll => 'r',
102 cb => \&IO::AIO::poll_cb);
103 79
104 # queue the request to open /etc/passwd 80 # queue the request to open /etc/passwd
105 aio_open "/etc/passwd", O_RDONLY, 0, sub { 81 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106 my $fh = shift 82 my $fh = shift
107 or die "error while opening: $!"; 83 or die "error while opening: $!";
108 84
109 # stat'ing filehandles is generally non-blocking 85 # stat'ing filehandles is generally non-blocking
110 my $size = -s $fh; 86 my $size = -s $fh;
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119 95
120 # file contents now in $contents 96 # file contents now in $contents
121 print $contents; 97 print $contents;
122 98
123 # exit event loop and program 99 # exit event loop and program
124 Event::unloop; 100 EV::unloop;
125 }; 101 };
126 }; 102 };
127 103
128 # possibly queue up other requests, or open GUI windows, 104 # possibly queue up other requests, or open GUI windows,
129 # check for sockets etc. etc. 105 # check for sockets etc. etc.
130 106
131 # process events as long as there are some: 107 # process events as long as there are some:
132 Event::loop; 108 EV::loop;
133 109
134=head1 REQUEST ANATOMY AND LIFETIME 110=head1 REQUEST ANATOMY AND LIFETIME
135 111
136Every C<aio_*> function creates a request. which is a C data structure not 112Every C<aio_*> function creates a request. which is a C data structure not
137directly visible to Perl. 113directly visible to Perl.
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187 163
188package IO::AIO; 164package IO::AIO;
189 165
190use Carp (); 166use Carp ();
191 167
192no warnings; 168use common::sense;
193use strict 'vars';
194 169
195use base 'Exporter'; 170use base 'Exporter';
196 171
197BEGIN { 172BEGIN {
198 our $VERSION = '3.21'; 173 our $VERSION = '4.0';
199 174
200 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
201 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202 aio_scandir aio_symlink aio_readlink aio_sync aio_fsync 177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
203 aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead 178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
179 aio_pathsync aio_readahead
204 aio_rename aio_link aio_move aio_copy aio_group 180 aio_rename aio_link aio_move aio_copy aio_group
205 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206 aio_chmod aio_utime aio_truncate); 182 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs
185 aio_wd);
207 186
208 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210 min_parallel max_parallel max_idle 189 min_parallel max_parallel max_idle idle_timeout
211 nreqs nready npending nthreads 190 nreqs nready npending nthreads
212 max_poll_time max_poll_reqs); 191 max_poll_time max_poll_reqs
192 sendfile fadvise madvise
193 mmap munmap munlock munlockall);
213 194
214 push @AIO_REQ, qw(aio_busy); # not exported 195 push @AIO_REQ, qw(aio_busy); # not exported
215 196
216 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217 198
218 require XSLoader; 199 require XSLoader;
219 XSLoader::load ("IO::AIO", $VERSION); 200 XSLoader::load ("IO::AIO", $VERSION);
220} 201}
221 202
222=head1 FUNCTIONS 203=head1 FUNCTIONS
204
205=head2 QUICK OVERVIEW
206
207This section simply lists the prototypes of the most important functions
208for quick reference. See the following sections for function-by-function
209documentation.
210
211 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status)
214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217 aio_readahead $fh,$offset,$length, $callback->($retval)
218 aio_stat $fh_or_path, $callback->($status)
219 aio_lstat $fh, $callback->($status)
220 aio_statvfs $fh_or_path, $callback->($statvfs)
221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
223 aio_truncate $fh_or_path, $offset, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status)
225 aio_unlink $pathname, $callback->($status)
226 aio_mknod $path, $mode, $dev, $callback->($status)
227 aio_link $srcpath, $dstpath, $callback->($status)
228 aio_symlink $srcpath, $dstpath, $callback->($status)
229 aio_readlink $path, $callback->($link)
230 aio_realpath $path, $callback->($link)
231 aio_rename $srcpath, $dstpath, $callback->($status)
232 aio_mkdir $pathname, $mode, $callback->($status)
233 aio_rmdir $pathname, $callback->($status)
234 aio_readdir $pathname, $callback->($entries)
235 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
238 aio_load $path, $data, $callback->($status)
239 aio_copy $srcpath, $dstpath, $callback->($status)
240 aio_move $srcpath, $dstpath, $callback->($status)
241 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
242 aio_rmtree $path, $callback->($status)
243 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status)
245 aio_fsync $fh, $callback->($status)
246 aio_fdatasync $fh, $callback->($status)
247 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248 aio_pathsync $path, $callback->($status)
249 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
250 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252 aio_mlockall $flags, $callback->($status)
253 aio_group $callback->(...)
254 aio_nop $callback->()
255
256 $prev_pri = aioreq_pri [$pri]
257 aioreq_nice $pri_adjust
258
259 IO::AIO::poll_wait
260 IO::AIO::poll_cb
261 IO::AIO::poll
262 IO::AIO::flush
263 IO::AIO::max_poll_reqs $nreqs
264 IO::AIO::max_poll_time $seconds
265 IO::AIO::min_parallel $nthreads
266 IO::AIO::max_parallel $nthreads
267 IO::AIO::max_idle $nthreads
268 IO::AIO::idle_timeout $seconds
269 IO::AIO::max_outstanding $maxreqs
270 IO::AIO::nreqs
271 IO::AIO::nready
272 IO::AIO::npending
273
274 IO::AIO::sendfile $ofh, $ifh, $offset, $count
275 IO::AIO::fadvise $fh, $offset, $len, $advice
276 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect
278 IO::AIO::munlock $scalar, $offset = 0, $length = undef
279 IO::AIO::munlockall
223 280
224=head2 AIO REQUEST FUNCTIONS 281=head2 AIO REQUEST FUNCTIONS
225 282
226All the C<aio_*> calls are more or less thin wrappers around the syscall 283All the C<aio_*> calls are more or less thin wrappers around the syscall
227with the same name (sans C<aio_>). The arguments are similar or identical, 284with the same name (sans C<aio_>). The arguments are similar or identical,
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307by the umask in effect then the request is being executed, so better never 364by the umask in effect then the request is being executed, so better never
308change the umask. 365change the umask.
309 366
310Example: 367Example:
311 368
312 aio_open "/etc/passwd", O_RDONLY, 0, sub { 369 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313 if ($_[0]) { 370 if ($_[0]) {
314 print "open successful, fh is $_[0]\n"; 371 print "open successful, fh is $_[0]\n";
315 ... 372 ...
316 } else { 373 } else {
317 die "open failed: $!\n"; 374 die "open failed: $!\n";
318 } 375 }
319 }; 376 };
320 377
378In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
379C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
380following POSIX and non-POSIX constants are available (missing ones on
381your system are, as usual, C<0>):
382
383C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
384C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
385C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
386
321 387
322=item aio_close $fh, $callback->($status) 388=item aio_close $fh, $callback->($status)
323 389
324Asynchronously close a file and call the callback with the result 390Asynchronously close a file and call the callback with the result
325code. 391code.
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375 441
376Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 442Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377reading at byte offset C<$in_offset>, and starts writing at the current 443reading at byte offset C<$in_offset>, and starts writing at the current
378file offset of C<$out_fh>. Because of that, it is not safe to issue more 444file offset of C<$out_fh>. Because of that, it is not safe to issue more
379than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each 445than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380other. 446other. The same C<$in_fh> works fine though, as this function does not
447move or use the file offset of C<$in_fh>.
381 448
449Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
450are written, and there is no way to find out how many more bytes have been
451read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
452number of bytes written to C<$out_fh>. Only if the result value equals
453C<$length> one can assume that C<$length> bytes have been read.
454
455Unlike with other C<aio_> functions, it makes a lot of sense to use
456C<aio_sendfile> on non-blocking sockets, as long as one end (typically
457the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
458the socket I/O will be non-blocking. Note, however, that you can run
459into a trap where C<aio_sendfile> reads some data with readahead, then
460fails to write all data, and when the socket is ready the next time, the
461data in the cache is already lost, forcing C<aio_sendfile> to again hit
462the disk. Explicit C<aio_read> + C<aio_write> let's you better control
463resource usage.
464
382This call tries to make use of a native C<sendfile> syscall to provide 465This call tries to make use of a native C<sendfile>-like syscall to
383zero-copy operation. For this to work, C<$out_fh> should refer to a 466provide zero-copy operation. For this to work, C<$out_fh> should refer to
384socket, and C<$in_fh> should refer to mmap'able file. 467a socket, and C<$in_fh> should refer to an mmap'able file.
385 468
386If the native sendfile call fails or is not implemented, it will be 469If a native sendfile cannot be found or it fails with C<ENOSYS>,
387emulated, so you can call C<aio_sendfile> on any type of filehandle 470C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
471C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388regardless of the limitations of the operating system. 472type of filehandle regardless of the limitations of the operating system.
389 473
390Please note, however, that C<aio_sendfile> can read more bytes from 474As native sendfile syscalls (as practically any non-POSIX interface hacked
391C<$in_fh> than are written, and there is no way to find out how many 475together in a hurry to improve benchmark numbers) tend to be rather buggy
392bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only 476on many systems, this implementation tries to work around some known bugs
393provides the number of bytes written to C<$out_fh>. Only if the result 477in Linux and FreeBSD kernels (probably others, too), but that might fail,
394value equals C<$length> one can assume that C<$length> bytes have been 478so you really really should check the return value of C<aio_sendfile> -
395read. 479fewre bytes than expected might have been transferred.
396 480
397 481
398=item aio_readahead $fh,$offset,$length, $callback->($retval) 482=item aio_readahead $fh,$offset,$length, $callback->($retval)
399 483
400C<aio_readahead> populates the page cache with data from a file so that 484C<aio_readahead> populates the page cache with data from a file so that
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423 507
424Currently, the stats are always 64-bit-stats, i.e. instead of returning an 508Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425error when stat'ing a large file, the results will be silently truncated 509error when stat'ing a large file, the results will be silently truncated
426unless perl itself is compiled with large file support. 510unless perl itself is compiled with large file support.
427 511
512To help interpret the mode and dev/rdev stat values, IO::AIO offers the
513following constants and functions (if not implemented, the constants will
514be C<0> and the functions will either C<croak> or fall back on traditional
515behaviour).
516
517C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
518C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
519C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
520
428Example: Print the length of F</etc/passwd>: 521Example: Print the length of F</etc/passwd>:
429 522
430 aio_stat "/etc/passwd", sub { 523 aio_stat "/etc/passwd", sub {
431 $_[0] and die "stat failed: $!"; 524 $_[0] and die "stat failed: $!";
432 print "size is ", -s _, "\n"; 525 print "size is ", -s _, "\n";
433 }; 526 };
434 527
435 528
529=item aio_statvfs $fh_or_path, $callback->($statvfs)
530
531Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
532whether a file handle or path was passed.
533
534On success, the callback is passed a hash reference with the following
535members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
536C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
537is passed.
538
539The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
540C<ST_NOSUID>.
541
542The following non-POSIX IO::AIO::ST_* flag masks are defined to
543their correct value when available, or to C<0> on systems that do
544not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
545C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
546C<ST_NODIRATIME> and C<ST_RELATIME>.
547
548Example: stat C</wd> and dump out the data if successful.
549
550 aio_statvfs "/wd", sub {
551 my $f = $_[0]
552 or die "statvfs: $!";
553
554 use Data::Dumper;
555 say Dumper $f;
556 };
557
558 # result:
559 {
560 bsize => 1024,
561 bfree => 4333064312,
562 blocks => 10253828096,
563 files => 2050765568,
564 flag => 4096,
565 favail => 2042092649,
566 bavail => 4333064312,
567 ffree => 2042092649,
568 namemax => 255,
569 frsize => 1024,
570 fsid => 1810
571 }
572
573
436=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 574=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437 575
438Works like perl's C<utime> function (including the special case of $atime 576Works like perl's C<utime> function (including the special case of $atime
439and $mtime being undef). Fractional times are supported if the underlying 577and $mtime being undef). Fractional times are supported if the underlying
440syscalls support them. 578syscalls support them.
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488 626
489The only (POSIX-) portable way of calling this function is: 627The only (POSIX-) portable way of calling this function is:
490 628
491 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 629 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492 630
631See C<aio_stat> for info about some potentially helpful extra constants
632and functions.
493 633
494=item aio_link $srcpath, $dstpath, $callback->($status) 634=item aio_link $srcpath, $dstpath, $callback->($status)
495 635
496Asynchronously create a new link to the existing object at C<$srcpath> at 636Asynchronously create a new link to the existing object at C<$srcpath> at
497the path C<$dstpath> and call the callback with the result code. 637the path C<$dstpath> and call the callback with the result code.
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508Asynchronously read the symlink specified by C<$path> and pass it to 648Asynchronously read the symlink specified by C<$path> and pass it to
509the callback. If an error occurs, nothing or undef gets passed to the 649the callback. If an error occurs, nothing or undef gets passed to the
510callback. 650callback.
511 651
512 652
653=item aio_realpath $path, $callback->($path)
654
655Asynchronously make the path absolute and resolve any symlinks in
656C<$path>. The resulting path only consists of directories (Same as
657L<Cwd::realpath>).
658
659This request can be used to get the absolute path of the current working
660directory by passing it a path of F<.> (a single dot).
661
662
513=item aio_rename $srcpath, $dstpath, $callback->($status) 663=item aio_rename $srcpath, $dstpath, $callback->($status)
514 664
515Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 665Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516rename(2) and call the callback with the result code. 666rename(2) and call the callback with the result code.
517 667
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539array-ref with the filenames. 689array-ref with the filenames.
540 690
541 691
542=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) 692=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543 693
544Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune 694Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
545behaviour and output format. In case of an error, C<$entries> will be 695tune behaviour and output format. In case of an error, C<$entries> will be
546C<undef>. 696C<undef>.
547 697
548The flags are a combination of the following constants, ORed together (the 698The flags are a combination of the following constants, ORed together (the
549flags will also be passed to the callback, possibly modified): 699flags will also be passed to the callback, possibly modified):
550 700
551=over 4 701=over 4
552 702
553=item IO::AIO::READDIR_DENTS 703=item IO::AIO::READDIR_DENTS
554 704
555When this flag is off, then the callback gets an arrayref with of names 705When this flag is off, then the callback gets an arrayref consisting of
556only (as with C<aio_readdir>), otherwise it gets an arrayref with 706names only (as with C<aio_readdir>), otherwise it gets an arrayref with
557C<[$name, $type, $inode]> arrayrefs, each describing a single directory 707C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558entry in more detail. 708entry in more detail.
559 709
560C<$name> is the name of the entry. 710C<$name> is the name of the entry.
561 711
… …
568C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to 718C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
569know, you have to run stat yourself. Also, for speed reasons, the C<$type> 719know, you have to run stat yourself. Also, for speed reasons, the C<$type>
570scalars are read-only: you can not modify them. 720scalars are read-only: you can not modify them.
571 721
572C<$inode> is the inode number (which might not be exact on systems with 64 722C<$inode> is the inode number (which might not be exact on systems with 64
573bit inode numbers and 32 bit perls). On systems that do not deliver the 723bit inode numbers and 32 bit perls). This field has unspecified content on
574inode information, this will always be zero. 724systems that do not deliver the inode information.
575 725
576=item IO::AIO::READDIR_DIRS_FIRST 726=item IO::AIO::READDIR_DIRS_FIRST
577 727
578When this flag is set, then the names will be returned in an order where 728When this flag is set, then the names will be returned in an order where
579likely directories come first. This is useful when you need to quickly 729likely directories come first, in optimal stat order. This is useful when
580find directories, or you want to find all directories while avoiding to 730you need to quickly find directories, or you want to find all directories
581stat() each entry. 731while avoiding to stat() each entry.
582 732
583If the system returns type information in readdir, then this is used 733If the system returns type information in readdir, then this is used
584to find directories directly. Otherwise, likely directories are files 734to find directories directly. Otherwise, likely directories are names
585beginning with ".", or otherwise files with no dots, of which files with 735beginning with ".", or otherwise names with no dots, of which names with
586short names are tried first. 736short names are tried first.
587 737
588=item IO::AIO::READDIR_STAT_ORDER 738=item IO::AIO::READDIR_STAT_ORDER
589 739
590When this flag is set, then the names will be returned in an order 740When this flag is set, then the names will be returned in an order
… …
597 747
598=item IO::AIO::READDIR_FOUND_UNKNOWN 748=item IO::AIO::READDIR_FOUND_UNKNOWN
599 749
600This flag should not be set when calling C<aio_readdirx>. Instead, it 750This flag should not be set when calling C<aio_readdirx>. Instead, it
601is being set by C<aio_readdirx>, when any of the C<$type>'s found were 751is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all 752C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
603C<$type>'s are known, which can be used to speed up some algorithms. 753C<$type>'s are known, which can be used to speed up some algorithms.
604 754
605=back 755=back
606 756
607 757
… …
635 785
636=item aio_copy $srcpath, $dstpath, $callback->($status) 786=item aio_copy $srcpath, $dstpath, $callback->($status)
637 787
638Try to copy the I<file> (directories not supported as either source or 788Try to copy the I<file> (directories not supported as either source or
639destination) from C<$srcpath> to C<$dstpath> and call the callback with 789destination) from C<$srcpath> to C<$dstpath> and call the callback with
640the C<0> (error) or C<-1> ok. 790a status of C<0> (ok) or C<-1> (error, see C<$!>).
641 791
642This is a composite request that creates the destination file with 792This is a composite request that creates the destination file with
643mode 0200 and copies the contents of the source file into it using 793mode 0200 and copies the contents of the source file into it using
644C<aio_sendfile>, followed by restoring atime, mtime, access mode and 794C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645uid/gid, in that order. 795uid/gid, in that order.
… …
657 my $grp = aio_group $cb; 807 my $grp = aio_group $cb;
658 808
659 aioreq_pri $pri; 809 aioreq_pri $pri;
660 add $grp aio_open $src, O_RDONLY, 0, sub { 810 add $grp aio_open $src, O_RDONLY, 0, sub {
661 if (my $src_fh = $_[0]) { 811 if (my $src_fh = $_[0]) {
662 my @stat = stat $src_fh; # hmm, might bock over nfs? 812 my @stat = stat $src_fh; # hmm, might block over nfs?
663 813
664 aioreq_pri $pri; 814 aioreq_pri $pri;
665 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { 815 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666 if (my $dst_fh = $_[0]) { 816 if (my $dst_fh = $_[0]) {
667 aioreq_pri $pri; 817 aioreq_pri $pri;
… …
714 864
715=item aio_move $srcpath, $dstpath, $callback->($status) 865=item aio_move $srcpath, $dstpath, $callback->($status)
716 866
717Try to move the I<file> (directories not supported as either source or 867Try to move the I<file> (directories not supported as either source or
718destination) from C<$srcpath> to C<$dstpath> and call the callback with 868destination) from C<$srcpath> to C<$dstpath> and call the callback with
719the C<0> (error) or C<-1> ok. 869a status of C<0> (ok) or C<-1> (error, see C<$!>).
720 870
721This is a composite request that tries to rename(2) the file first; if 871This is a composite request that tries to rename(2) the file first; if
722rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if 872rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723that is successful, unlinks the C<$srcpath>. 873that is successful, unlinks the C<$srcpath>.
724 874
… …
735 if ($_[0] && $! == EXDEV) { 885 if ($_[0] && $! == EXDEV) {
736 aioreq_pri $pri; 886 aioreq_pri $pri;
737 add $grp aio_copy $src, $dst, sub { 887 add $grp aio_copy $src, $dst, sub {
738 $grp->result ($_[0]); 888 $grp->result ($_[0]);
739 889
740 if (!$_[0]) { 890 unless ($_[0]) {
741 aioreq_pri $pri; 891 aioreq_pri $pri;
742 add $grp aio_unlink $src; 892 add $grp aio_unlink $src;
743 } 893 }
744 }; 894 };
745 } else { 895 } else {
… …
789Then entries will be sorted into likely directories a non-initial dot 939Then entries will be sorted into likely directories a non-initial dot
790currently) and likely non-directories (see C<aio_readdirx>). Then every 940currently) and likely non-directories (see C<aio_readdirx>). Then every
791entry plus an appended C</.> will be C<stat>'ed, likely directories first, 941entry plus an appended C</.> will be C<stat>'ed, likely directories first,
792in order of their inode numbers. If that succeeds, it assumes that the 942in order of their inode numbers. If that succeeds, it assumes that the
793entry is a directory or a symlink to directory (which will be checked 943entry is a directory or a symlink to directory (which will be checked
794seperately). This is often faster than stat'ing the entry itself because 944separately). This is often faster than stat'ing the entry itself because
795filesystems might detect the type of the entry without reading the inode 945filesystems might detect the type of the entry without reading the inode
796data (e.g. ext2fs filetype feature), even on systems that cannot return 946data (e.g. ext2fs filetype feature), even on systems that cannot return
797the filetype information on readdir. 947the filetype information on readdir.
798 948
799If the known number of directories (link count - 2) has been reached, the 949If the known number of directories (link count - 2) has been reached, the
… …
937callback with the fdatasync result code. 1087callback with the fdatasync result code.
938 1088
939If this call isn't available because your OS lacks it or it couldn't be 1089If this call isn't available because your OS lacks it or it couldn't be
940detected, it will be emulated by calling C<fsync> instead. 1090detected, it will be emulated by calling C<fsync> instead.
941 1091
1092=item aio_syncfs $fh, $callback->($status)
1093
1094Asynchronously call the syncfs syscall to sync the filesystem associated
1095to the given filehandle and call the callback with the syncfs result
1096code. If syncfs is not available, calls sync(), but returns C<-1> and sets
1097errno to C<ENOSYS> nevertheless.
1098
942=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 1099=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943 1100
944Sync the data portion of the file specified by C<$offset> and C<$length> 1101Sync the data portion of the file specified by C<$offset> and C<$length>
945to disk (but NOT the metadata), by calling the Linux-specific 1102to disk (but NOT the metadata), by calling the Linux-specific
946sync_file_range call. If sync_file_range is not available or it returns 1103sync_file_range call. If sync_file_range is not available or it returns
… …
957composite request intended to sync directories after directory operations 1114composite request intended to sync directories after directory operations
958(E.g. rename). This might not work on all operating systems or have any 1115(E.g. rename). This might not work on all operating systems or have any
959specific effect, but usually it makes sure that directory changes get 1116specific effect, but usually it makes sure that directory changes get
960written to disc. It works for anything that can be opened for read-only, 1117written to disc. It works for anything that can be opened for read-only,
961not just directories. 1118not just directories.
1119
1120Future versions of this function might fall back to other methods when
1121C<fsync> on the directory fails (such as calling C<sync>).
962 1122
963Passes C<0> when everything went ok, and C<-1> on error. 1123Passes C<0> when everything went ok, and C<-1> on error.
964 1124
965=cut 1125=cut
966 1126
… …
987 }; 1147 };
988 1148
989 $grp 1149 $grp
990} 1150}
991 1151
1152=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1153
1154This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1155scalars (see the C<IO::AIO::mmap> function, although it also works on data
1156scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1157scalar must only be modified in-place while an aio operation is pending on
1158it).
1159
1160It calls the C<msync> function of your OS, if available, with the memory
1161area starting at C<$offset> in the string and ending C<$length> bytes
1162later. If C<$length> is negative, counts from the end, and if C<$length>
1163is C<undef>, then it goes till the end of the string. The flags can be
1164a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
1165C<IO::AIO::MS_SYNC>.
1166
1167=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1168
1169This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1170scalars.
1171
1172It touches (reads or writes) all memory pages in the specified
1173range inside the scalar. All caveats and parameters are the same
1174as for C<aio_msync>, above, except for flags, which must be either
1175C<0> (which reads all pages and ensures they are instantiated) or
1176C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
1177writing an octet from it, which dirties the page).
1178
1179=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1180
1181This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1182scalars.
1183
1184It reads in all the pages of the underlying storage into memory (if any)
1185and locks them, so they are not getting swapped/paged out or removed.
1186
1187If C<$length> is undefined, then the scalar will be locked till the end.
1188
1189On systems that do not implement C<mlock>, this function returns C<-1>
1190and sets errno to C<ENOSYS>.
1191
1192Note that the corresponding C<munlock> is synchronous and is
1193documented under L<MISCELLANEOUS FUNCTIONS>.
1194
1195Example: open a file, mmap and mlock it - both will be undone when
1196C<$data> gets destroyed.
1197
1198 open my $fh, "<", $path or die "$path: $!";
1199 my $data;
1200 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1201 aio_mlock $data; # mlock in background
1202
1203=item aio_mlockall $flags, $callback->($status)
1204
1205Calls the C<mlockall> function with the given C<$flags> (a combination of
1206C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
1207
1208On systems that do not implement C<mlockall>, this function returns C<-1>
1209and sets errno to C<ENOSYS>.
1210
1211Note that the corresponding C<munlockall> is synchronous and is
1212documented under L<MISCELLANEOUS FUNCTIONS>.
1213
1214Example: asynchronously lock all current and future pages into memory.
1215
1216 aio_mlockall IO::AIO::MCL_FUTURE;
1217
992=item aio_group $callback->(...) 1218=item aio_group $callback->(...)
993 1219
994This is a very special aio request: Instead of doing something, it is a 1220This is a very special aio request: Instead of doing something, it is a
995container for other aio requests, which is useful if you want to bundle 1221container for other aio requests, which is useful if you want to bundle
996many requests into a single, composite, request with a definite callback 1222many requests into a single, composite, request with a definite callback
… …
1131=item $grp->cancel_subs 1357=item $grp->cancel_subs
1132 1358
1133Cancel all subrequests and clears any feeder, but not the group request 1359Cancel all subrequests and clears any feeder, but not the group request
1134itself. Useful when you queued a lot of events but got a result early. 1360itself. Useful when you queued a lot of events but got a result early.
1135 1361
1362The group request will finish normally (you cannot add requests to the
1363group).
1364
1136=item $grp->result (...) 1365=item $grp->result (...)
1137 1366
1138Set the result value(s) that will be passed to the group callback when all 1367Set the result value(s) that will be passed to the group callback when all
1139subrequests have finished and set the groups errno to the current value 1368subrequests have finished and set the groups errno to the current value
1140of errno (just like calling C<errno> without an error number). By default, 1369of errno (just like calling C<errno> without an error number). By default,
… …
1208=over 4 1437=over 4
1209 1438
1210=item $fileno = IO::AIO::poll_fileno 1439=item $fileno = IO::AIO::poll_fileno
1211 1440
1212Return the I<request result pipe file descriptor>. This filehandle must be 1441Return the I<request result pipe file descriptor>. This filehandle must be
1213polled for reading by some mechanism outside this module (e.g. Event or 1442polled for reading by some mechanism outside this module (e.g. EV, Glib,
1214select, see below or the SYNOPSIS). If the pipe becomes readable you have 1443select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1215to call C<poll_cb> to check the results. 1444you have to call C<poll_cb> to check the results.
1216 1445
1217See C<poll_cb> for an example. 1446See C<poll_cb> for an example.
1218 1447
1219=item IO::AIO::poll_cb 1448=item IO::AIO::poll_cb
1220 1449
1221Process some outstanding events on the result pipe. You have to call this 1450Process some outstanding events on the result pipe. You have to call
1222regularly. Returns C<0> if all events could be processed, or C<-1> if it 1451this regularly. Returns C<0> if all events could be processed (or there
1223returned earlier for whatever reason. Returns immediately when no events 1452were no events to process), or C<-1> if it returned earlier for whatever
1224are outstanding. The amount of events processed depends on the settings of 1453reason. Returns immediately when no events are outstanding. The amount of
1225C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. 1454events processed depends on the settings of C<IO::AIO::max_poll_req> and
1455C<IO::AIO::max_poll_time>.
1226 1456
1227If not all requests were processed for whatever reason, the filehandle 1457If not all requests were processed for whatever reason, the filehandle
1228will still be ready when C<poll_cb> returns, so normally you don't have to 1458will still be ready when C<poll_cb> returns, so normally you don't have to
1229do anything special to have it called later. 1459do anything special to have it called later.
1230 1460
1461Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1462ready, it can be beneficial to call this function from loops which submit
1463a lot of requests, to make sure the results get processed when they become
1464available and not just when the loop is finished and the event loop takes
1465over again. This function returns very fast when there are no outstanding
1466requests.
1467
1231Example: Install an Event watcher that automatically calls 1468Example: Install an Event watcher that automatically calls
1232IO::AIO::poll_cb with high priority: 1469IO::AIO::poll_cb with high priority (more examples can be found in the
1470SYNOPSIS section, at the top of this document):
1233 1471
1234 Event->io (fd => IO::AIO::poll_fileno, 1472 Event->io (fd => IO::AIO::poll_fileno,
1235 poll => 'r', async => 1, 1473 poll => 'r', async => 1,
1236 cb => \&IO::AIO::poll_cb); 1474 cb => \&IO::AIO::poll_cb);
1475
1476=item IO::AIO::poll_wait
1477
1478If there are any outstanding requests and none of them in the result
1479phase, wait till the result filehandle becomes ready for reading (simply
1480does a C<select> on the filehandle. This is useful if you want to
1481synchronously wait for some requests to finish).
1482
1483See C<nreqs> for an example.
1484
1485=item IO::AIO::poll
1486
1487Waits until some requests have been handled.
1488
1489Returns the number of requests processed, but is otherwise strictly
1490equivalent to:
1491
1492 IO::AIO::poll_wait, IO::AIO::poll_cb
1493
1494=item IO::AIO::flush
1495
1496Wait till all outstanding AIO requests have been handled.
1497
1498Strictly equivalent to:
1499
1500 IO::AIO::poll_wait, IO::AIO::poll_cb
1501 while IO::AIO::nreqs;
1237 1502
1238=item IO::AIO::max_poll_reqs $nreqs 1503=item IO::AIO::max_poll_reqs $nreqs
1239 1504
1240=item IO::AIO::max_poll_time $seconds 1505=item IO::AIO::max_poll_time $seconds
1241 1506
… …
1266 # use a low priority so other tasks have priority 1531 # use a low priority so other tasks have priority
1267 Event->io (fd => IO::AIO::poll_fileno, 1532 Event->io (fd => IO::AIO::poll_fileno,
1268 poll => 'r', nice => 1, 1533 poll => 'r', nice => 1,
1269 cb => &IO::AIO::poll_cb); 1534 cb => &IO::AIO::poll_cb);
1270 1535
1271=item IO::AIO::poll_wait
1272
1273If there are any outstanding requests and none of them in the result
1274phase, wait till the result filehandle becomes ready for reading (simply
1275does a C<select> on the filehandle. This is useful if you want to
1276synchronously wait for some requests to finish).
1277
1278See C<nreqs> for an example.
1279
1280=item IO::AIO::poll
1281
1282Waits until some requests have been handled.
1283
1284Returns the number of requests processed, but is otherwise strictly
1285equivalent to:
1286
1287 IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289=item IO::AIO::flush
1290
1291Wait till all outstanding AIO requests have been handled.
1292
1293Strictly equivalent to:
1294
1295 IO::AIO::poll_wait, IO::AIO::poll_cb
1296 while IO::AIO::nreqs;
1297
1298=back 1536=back
1299 1537
1300=head3 CONTROLLING THE NUMBER OF THREADS 1538=head3 CONTROLLING THE NUMBER OF THREADS
1301 1539
1302=over 1540=over
… …
1335 1573
1336Under normal circumstances you don't need to call this function. 1574Under normal circumstances you don't need to call this function.
1337 1575
1338=item IO::AIO::max_idle $nthreads 1576=item IO::AIO::max_idle $nthreads
1339 1577
1340Limit the number of threads (default: 4) that are allowed to idle (i.e., 1578Limit the number of threads (default: 4) that are allowed to idle
1341threads that did not get a request to process within 10 seconds). That 1579(i.e., threads that did not get a request to process within the idle
1342means if a thread becomes idle while C<$nthreads> other threads are also 1580timeout (default: 10 seconds). That means if a thread becomes idle while
1343idle, it will free its resources and exit. 1581C<$nthreads> other threads are also idle, it will free its resources and
1582exit.
1344 1583
1345This is useful when you allow a large number of threads (e.g. 100 or 1000) 1584This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346to allow for extremely high load situations, but want to free resources 1585to allow for extremely high load situations, but want to free resources
1347under normal circumstances (1000 threads can easily consume 30MB of RAM). 1586under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348 1587
1349The default is probably ok in most situations, especially if thread 1588The default is probably ok in most situations, especially if thread
1350creation is fast. If thread creation is very slow on your system you might 1589creation is fast. If thread creation is very slow on your system you might
1351want to use larger values. 1590want to use larger values.
1352 1591
1592=item IO::AIO::idle_timeout $seconds
1593
1594Sets the minimum idle timeout (default 10) after which worker threads are
1595allowed to exit. SEe C<IO::AIO::max_idle>.
1596
1353=item IO::AIO::max_outstanding $maxreqs 1597=item IO::AIO::max_outstanding $maxreqs
1598
1599Sets the maximum number of outstanding requests to C<$nreqs>. If
1600you do queue up more than this number of requests, the next call to
1601C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1602C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
1603longer exceeded.
1604
1605In other words, this setting does not enforce a queue limit, but can be
1606used to make poll functions block if the limit is exceeded.
1354 1607
1355This is a very bad function to use in interactive programs because it 1608This is a very bad function to use in interactive programs because it
1356blocks, and a bad way to reduce concurrency because it is inexact: Better 1609blocks, and a bad way to reduce concurrency because it is inexact: Better
1357use an C<aio_group> together with a feed callback. 1610use an C<aio_group> together with a feed callback.
1358 1611
1359Sets the maximum number of outstanding requests to C<$nreqs>. If you 1612It's main use is in scripts without an event loop - when you want to stat
1360do queue up more than this number of requests, the next call to the 1613a lot of files, you can write somehting like this:
1361C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362function will block until the limit is no longer exceeded.
1363 1614
1364The default value is very large, so there is no practical limit on the 1615 IO::AIO::max_outstanding 32;
1365number of outstanding requests.
1366 1616
1367You can still queue as many requests as you want. Therefore, 1617 for my $path (...) {
1368C<max_outstanding> is mainly useful in simple scripts (with low values) or 1618 aio_stat $path , ...;
1369as a stop gap to shield against fatal memory overflow (with large values). 1619 IO::AIO::poll_cb;
1620 }
1621
1622 IO::AIO::flush;
1623
1624The call to C<poll_cb> inside the loop will normally return instantly, but
1625as soon as more thna C<32> reqeusts are in-flight, it will block until
1626some requests have been handled. This keeps the loop from pushing a large
1627number of C<aio_stat> requests onto the queue.
1628
1629The default value for C<max_outstanding> is very large, so there is no
1630practical limit on the number of outstanding requests.
1370 1631
1371=back 1632=back
1372 1633
1373=head3 STATISTICAL INFORMATION 1634=head3 STATISTICAL INFORMATION
1374 1635
… …
1394Returns the number of requests currently in the pending state (executed, 1655Returns the number of requests currently in the pending state (executed,
1395but not yet processed by poll_cb). 1656but not yet processed by poll_cb).
1396 1657
1397=back 1658=back
1398 1659
1660=head3 MISCELLANEOUS FUNCTIONS
1661
1662IO::AIO implements some functions that might be useful, but are not
1663asynchronous.
1664
1665=over 4
1666
1667=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1668
1669Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1670but is blocking (this makes most sense if you know the input data is
1671likely cached already and the output filehandle is set to non-blocking
1672operations).
1673
1674Returns the number of bytes copied, or C<-1> on error.
1675
1676=item IO::AIO::fadvise $fh, $offset, $len, $advice
1677
1678Simply calls the C<posix_fadvise> function (see its
1679manpage for details). The following advice constants are
1680available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1681C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1682C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1683
1684On systems that do not implement C<posix_fadvise>, this function returns
1685ENOSYS, otherwise the return value of C<posix_fadvise>.
1686
1687=item IO::AIO::madvise $scalar, $offset, $len, $advice
1688
1689Simply calls the C<posix_madvise> function (see its
1690manpage for details). The following advice constants are
1691available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1692C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
1693
1694On systems that do not implement C<posix_madvise>, this function returns
1695ENOSYS, otherwise the return value of C<posix_madvise>.
1696
1697=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1698
1699Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1700$scalar (see its manpage for details). The following protect
1701constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1702C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1703
1704On systems that do not implement C<mprotect>, this function returns
1705ENOSYS, otherwise the return value of C<mprotect>.
1706
1707=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1708
1709Memory-maps a file (or anonymous memory range) and attaches it to the
1710given C<$scalar>, which will act like a string scalar.
1711
1712The only operations allowed on the scalar are C<substr>/C<vec> that don't
1713change the string length, and most read-only operations such as copying it
1714or searching it with regexes and so on.
1715
1716Anything else is unsafe and will, at best, result in memory leaks.
1717
1718The memory map associated with the C<$scalar> is automatically removed
1719when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
1720C<IO::AIO::munmap> functions are called.
1721
1722This calls the C<mmap>(2) function internally. See your system's manual
1723page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1724
1725The C<$length> must be larger than zero and smaller than the actual
1726filesize.
1727
1728C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1729C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1730
1731C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
1732C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
1733not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
1734(which is set to C<MAP_ANON> if your system only provides this
1735constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
1736C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
1737C<IO::AIO::MAP_NONBLOCK>
1738
1739If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1740
1741C<$offset> is the offset from the start of the file - it generally must be
1742a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1743
1744Example:
1745
1746 use Digest::MD5;
1747 use IO::AIO;
1748
1749 open my $fh, "<verybigfile"
1750 or die "$!";
1751
1752 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1753 or die "verybigfile: $!";
1754
1755 my $fast_md5 = md5 $data;
1756
1757=item IO::AIO::munmap $scalar
1758
1759Removes a previous mmap and undefines the C<$scalar>.
1760
1761=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1762
1763Calls the C<munlock> function, undoing the effects of a previous
1764C<aio_mlock> call (see its description for details).
1765
1766=item IO::AIO::munlockall
1767
1768Calls the C<munlockall> function.
1769
1770On systems that do not implement C<munlockall>, this function returns
1771ENOSYS, otherwise the return value of C<munlockall>.
1772
1773=back
1774
1399=cut 1775=cut
1400 1776
1401min_parallel 8; 1777min_parallel 8;
1402 1778
1403END { flush } 1779END { flush }
1404 1780
14051; 17811;
1406 1782
1783=head1 EVENT LOOP INTEGRATION
1784
1785It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
1786automatically into many event loops:
1787
1788 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
1789 use AnyEvent::AIO;
1790
1791You can also integrate IO::AIO manually into many event loops, here are
1792some examples of how to do this:
1793
1794 # EV integration
1795 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
1796
1797 # Event integration
1798 Event->io (fd => IO::AIO::poll_fileno,
1799 poll => 'r',
1800 cb => \&IO::AIO::poll_cb);
1801
1802 # Glib/Gtk2 integration
1803 add_watch Glib::IO IO::AIO::poll_fileno,
1804 in => sub { IO::AIO::poll_cb; 1 };
1805
1806 # Tk integration
1807 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
1808 readable => \&IO::AIO::poll_cb);
1809
1810 # Danga::Socket integration
1811 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1812 \&IO::AIO::poll_cb);
1813
1407=head2 FORK BEHAVIOUR 1814=head2 FORK BEHAVIOUR
1408 1815
1409This module should do "the right thing" when the process using it forks: 1816Usage of pthreads in a program changes the semantics of fork
1817considerably. Specifically, only async-safe functions can be called after
1818fork. Perl doesn't know about this, so in general, you cannot call fork
1819with defined behaviour in perl if pthreads are involved. IO::AIO uses
1820pthreads, so this applies, but many other extensions and (for inexplicable
1821reasons) perl itself often is linked against pthreads, so this limitation
1822applies to quite a lot of perls.
1410 1823
1411Before the fork, IO::AIO enters a quiescent state where no requests 1824This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412can be added in other threads and no results will be processed. After 1825only works in the process that loaded it. Forking is fully supported, but
1413the fork the parent simply leaves the quiescent state and continues 1826using IO::AIO in the child is not.
1414request/result processing, while the child frees the request/result queue
1415(so that the requests started before the fork will only be handled in the
1416parent). Threads will be started on demand until the limit set in the
1417parent process has been reached again.
1418 1827
1419In short: the parent will, after a short pause, continue as if fork had 1828You might get around by not I<using> IO::AIO before (or after)
1420not been called, while the child will act as if IO::AIO has not been used 1829forking. You could also try to call the L<IO::AIO::reinit> function in the
1421yet. 1830child:
1831
1832=over 4
1833
1834=item IO::AIO::reinit
1835
1836Abandons all current requests and I/O threads and simply reinitialises all
1837data structures. This is not an operation supported by any standards, but
1838happens to work on GNU/Linux and some newer BSD systems.
1839
1840The only reasonable use for this function is to call it after forking, if
1841C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
1842the process will result in undefined behaviour. Calling it at any time
1843will also result in any undefined (by POSIX) behaviour.
1844
1845=back
1422 1846
1423=head2 MEMORY USAGE 1847=head2 MEMORY USAGE
1424 1848
1425Per-request usage: 1849Per-request usage:
1426 1850

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