[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.143 by root, Thu Nov 20 09:01:40 2008 UTC vs.
Revision 1.183 by root, Sun Sep 12 03:40:05 2010 UTC

 =head1 SYNOPSIS
  use IO::AIO;
- aio_open "/etc/passwd", O_RDONLY, 0, sub {
+ aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
     my $fh = shift
        or die "/etc/passwd: $!";
     ...
  };
  $req->cancel; # cancel request if still in queue
  my $grp = aio_group sub { print "all stats done\n" };
  add $grp aio_stat "..." for ...;
- # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
- use AnyEvent::AIO;
- # EV integration
- my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
- # Event integration
- Event->io (fd => IO::AIO::poll_fileno,
-            poll => 'r',
-            cb => \&IO::AIO::poll_cb);
- # Glib/Gtk2 integration
- add_watch Glib::IO IO::AIO::poll_fileno,
-           in => sub { IO::AIO::poll_cb; 1 };
- # Tk integration
- Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
-                           readable => \&IO::AIO::poll_cb);
- # Danga::Socket integration
- Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
-                             \&IO::AIO::poll_cb);
 =head1 DESCRIPTION
 This module implements asynchronous I/O using whatever means your
-operating system supports.
+operating system supports. It is implemented as an interface to C<libeio>
+(L<http://software.schmorp.de/pkg/libeio.html>).
 Asynchronous means that operations that can normally block your program
 (e.g. reading from disk) will be done asynchronously: the operation
 will still block, but you can do something else in the meantime. This
 is extremely useful for programs that need to stay interactive even
 on a RAID volume or over NFS when you do a number of stat operations
 concurrently.
 While most of this works on all types of file descriptors (for
 example sockets), using these functions on file descriptors that
-support nonblocking operation (again, sockets, pipes etc.) is very
+support nonblocking operation (again, sockets, pipes etc.) is
-inefficient. Use an event loop for that (such as the L<Event|Event>
+very inefficient. Use an event loop for that (such as the L<EV>
 module): IO::AIO will naturally fit into such an event loop itself.
 In this version, a number of threads are started that execute your
 requests and signal their completion. You don't need thread support
 in perl, and the threads created by this module will not be visible
 yourself, always call C<poll_cb> from within the same thread, or never
 call C<poll_cb> (or other C<aio_> functions) recursively.
 =head2 EXAMPLE
-This is a simple example that uses the Event module and loads
+This is a simple example that uses the EV module and loads
 F</etc/passwd> asynchronously:
    use Fcntl;
-   use Event;
+   use EV;
    use IO::AIO;
-   # register the IO::AIO callback with Event
+   # register the IO::AIO callback with EV
-   Event->io (fd => IO::AIO::poll_fileno,
+   my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
-              poll => 'r',
-              cb => \&IO::AIO::poll_cb);
    # queue the request to open /etc/passwd
-   aio_open "/etc/passwd", O_RDONLY, 0, sub {
+   aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
       my $fh = shift
          or die "error while opening: $!";
       # stat'ing filehandles is generally non-blocking
       my $size = -s $fh;
          # file contents now in $contents
          print $contents;
          # exit event loop and program
-         Event::unloop;
+         EV::unloop;
       };
    };
    # possibly queue up other requests, or open GUI windows,
    # check for sockets etc. etc.
    # process events as long as there are some:
-   Event::loop;
+   EV::loop;
 =head1 REQUEST ANATOMY AND LIFETIME
 Every C<aio_*> function creates a request. which is a C data structure not
 directly visible to Perl.
 package IO::AIO;
 use Carp ();
-no warnings;
+use common::sense;
-use strict 'vars';
 use base 'Exporter';
 BEGIN {
-   our $VERSION = '3.17';
+   our $VERSION = '3.65';
    our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
-                     aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
+                     aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
                      aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
                      aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
                      aio_rename aio_link aio_move aio_copy aio_group
                      aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
-                     aio_chmod aio_utime aio_truncate);
+                     aio_chmod aio_utime aio_truncate
+                     aio_msync aio_mtouch aio_mlock aio_mlockall
+                     aio_statvfs);
    our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
    our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
                        min_parallel max_parallel max_idle
                        nreqs nready npending nthreads
-                       max_poll_time max_poll_reqs);
+                       max_poll_time max_poll_reqs
+                       sendfile fadvise madvise
+                       mmap munmap munlock munlockall);
    push @AIO_REQ, qw(aio_busy); # not exported
    @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
    require XSLoader;
    XSLoader::load ("IO::AIO", $VERSION);
 }
 =head1 FUNCTIONS
+=head2 QUICK OVERVIEW
+This section simply lists the prototypes of the most important functions
+for quick reference. See the following sections for function-by-function
+documentation.
+   aio_open $pathname, $flags, $mode, $callback->($fh)
+   aio_close $fh, $callback->($status)
+   aio_read  $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
+   aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
+   aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
+   aio_readahead $fh,$offset,$length, $callback->($retval)
+   aio_stat  $fh_or_path, $callback->($status)
+   aio_lstat $fh, $callback->($status)
+   aio_statvfs $fh_or_path, $callback->($statvfs)
+   aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
+   aio_chown $fh_or_path, $uid, $gid, $callback->($status)
+   aio_truncate $fh_or_path, $offset, $callback->($status)
+   aio_chmod $fh_or_path, $mode, $callback->($status)
+   aio_unlink $pathname, $callback->($status)
+   aio_mknod $path, $mode, $dev, $callback->($status)
+   aio_link $srcpath, $dstpath, $callback->($status)
+   aio_symlink $srcpath, $dstpath, $callback->($status)
+   aio_readlink $path, $callback->($link)
+   aio_rename $srcpath, $dstpath, $callback->($status)
+   aio_mkdir $pathname, $mode, $callback->($status)
+   aio_rmdir $pathname, $callback->($status)
+   aio_readdir $pathname, $callback->($entries)
+   aio_readdirx $pathname, $flags, $callback->($entries, $flags)
+      IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
+      IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
+   aio_load $path, $data, $callback->($status)
+   aio_copy $srcpath, $dstpath, $callback->($status)
+   aio_move $srcpath, $dstpath, $callback->($status)
+   aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
+   aio_rmtree $path, $callback->($status)
+   aio_sync $callback->($status)
+   aio_fsync $fh, $callback->($status)
+   aio_fdatasync $fh, $callback->($status)
+   aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
+   aio_pathsync $path, $callback->($status)
+   aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
+   aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
+   aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
+   aio_mlockall $flags, $callback->($status)
+   aio_group $callback->(...)
+   aio_nop $callback->()
+   $prev_pri = aioreq_pri [$pri]
+   aioreq_nice $pri_adjust
+   IO::AIO::poll_wait
+   IO::AIO::poll_cb
+   IO::AIO::poll
+   IO::AIO::flush
+   IO::AIO::max_poll_reqs $nreqs
+   IO::AIO::max_poll_time $seconds
+   IO::AIO::min_parallel $nthreads
+   IO::AIO::max_parallel $nthreads
+   IO::AIO::max_idle $nthreads
+   IO::AIO::max_outstanding $maxreqs
+   IO::AIO::nreqs
+   IO::AIO::nready
+   IO::AIO::npending
+   IO::AIO::sendfile $ofh, $ifh, $offset, $count
+   IO::AIO::fadvise $fh, $offset, $len, $advice
+   IO::AIO::munlock $scalar, $offset = 0, $length = undef
+   IO::AIO::munlockall
 =head2 AIO REQUEST FUNCTIONS
 All the C<aio_*> calls are more or less thin wrappers around the syscall
 with the same name (sans C<aio_>). The arguments are similar or identical,
 by the umask in effect then the request is being executed, so better never
 change the umask.
 Example:
-   aio_open "/etc/passwd", O_RDONLY, 0, sub {
+   aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
       if ($_[0]) {
          print "open successful, fh is $_[0]\n";
          ...
       } else {
          die "open failed: $!\n";
 =item aio_read  $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
 =item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
-Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
+Reads or writes C<$length> bytes from or to the specified C<$fh> and
-into the scalar given by C<$data> and offset C<$dataoffset> and calls the
+C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
-callback without the actual number of bytes read (or -1 on error, just
+and calls the callback without the actual number of bytes read (or -1 on
-like the syscall).
+error, just like the syscall).
+C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
+offset plus the actual number of bytes read.
 If C<$offset> is undefined, then the current file descriptor offset will
 be used (and updated), otherwise the file descriptor offset will not be
 changed by these calls.
-If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
+If C<$length> is undefined in C<aio_write>, use the remaining length of
+C<$data>.
 If C<$dataoffset> is less than zero, it will be counted from the end of
 C<$data>.
 The C<$data> scalar I<MUST NOT> be modified in any way while the request
 than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
 other.
 This call tries to make use of a native C<sendfile> syscall to provide
 zero-copy operation. For this to work, C<$out_fh> should refer to a
-socket, and C<$in_fh> should refer to mmap'able file.
+socket, and C<$in_fh> should refer to an mmap'able file.
-If the native sendfile call fails or is not implemented, it will be
+If a native sendfile cannot be found or it fails with C<ENOSYS>,
+C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
-emulated, so you can call C<aio_sendfile> on any type of filehandle
+it will be emulated, so you can call C<aio_sendfile> on any type of
-regardless of the limitations of the operating system.
+filehandle regardless of the limitations of the operating system.
 Please note, however, that C<aio_sendfile> can read more bytes from
 C<$in_fh> than are written, and there is no way to find out how many
 bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
 provides the number of bytes written to C<$out_fh>. Only if the result
       $_[0] and die "stat failed: $!";
       print "size is ", -s _, "\n";
    };
+=item aio_statvfs $fh_or_path, $callback->($statvfs)
+Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
+whether a file handle or path was passed.
+On success, the callback is passed a hash reference with the following
+members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
+C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
+is passed.
+The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
+C<ST_NOSUID>.
+The following non-POSIX IO::AIO::ST_* flag masks are defined to
+their correct value when available, or to C<0> on systems that do
+not support them:  C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
+C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
+C<ST_NODIRATIME> and C<ST_RELATIME>.
+Example: stat C</wd> and dump out the data if successful.
+   aio_statvfs "/wd", sub {
+      my $f = $_[0]
+         or die "statvfs: $!";
+      use Data::Dumper;
+      say Dumper $f;
+   };
+   # result:
+   {
+      bsize   => 1024,
+      bfree   => 4333064312,
+      blocks  => 10253828096,
+      files   => 2050765568,
+      flag    => 4096,
+      favail  => 2042092649,
+      bavail  => 4333064312,
+      ffree   => 2042092649,
+      namemax => 255,
+      frsize  => 1024,
+      fsid    => 1810
+   }
 =item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
 Works like perl's C<utime> function (including the special case of $atime
 and $mtime being undef). Fractional times are supported if the underlying
 syscalls support them.
 Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
 directory (i.e. opendir + readdir + closedir). The entries will not be
 sorted, and will B<NOT> include the C<.> and C<..> entries.
-The callback a single argument which is either C<undef> or an array-ref
+The callback is passed a single argument which is either C<undef> or an
-with the filenames.
+array-ref with the filenames.
+=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
+Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
+behaviour and output format. In case of an error, C<$entries> will be
+C<undef>.
+The flags are a combination of the following constants, ORed together (the
+flags will also be passed to the callback, possibly modified):
+=over 4
+=item IO::AIO::READDIR_DENTS
+When this flag is off, then the callback gets an arrayref with of names
+only (as with C<aio_readdir>), otherwise it gets an arrayref with
+C<[$name, $type, $inode]> arrayrefs, each describing a single directory
+entry in more detail.
+C<$name> is the name of the entry.
+C<$type> is one of the C<IO::AIO::DT_xxx> constants:
+C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
+C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
+C<IO::AIO::DT_WHT>.
+C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
+know, you have to run stat yourself. Also, for speed reasons, the C<$type>
+scalars are read-only: you can not modify them.
+C<$inode> is the inode number (which might not be exact on systems with 64
+bit inode numbers and 32 bit perls). This field has unspecified content on
+systems that do not deliver the inode information.
+=item IO::AIO::READDIR_DIRS_FIRST
+When this flag is set, then the names will be returned in an order where
+likely directories come first. This is useful when you need to quickly
+find directories, or you want to find all directories while avoiding to
+stat() each entry.
+If the system returns type information in readdir, then this is used
+to find directories directly.  Otherwise, likely directories are files
+beginning with ".", or otherwise files with no dots, of which files with
+short names are tried first.
+=item IO::AIO::READDIR_STAT_ORDER
+When this flag is set, then the names will be returned in an order
+suitable for stat()'ing each one. That is, when you plan to stat()
+all files in the given directory, then the returned order will likely
+be fastest.
+If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
+the likely dirs come first, resulting in a less optimal stat order.
+=item IO::AIO::READDIR_FOUND_UNKNOWN
+This flag should not be set when calling C<aio_readdirx>. Instead, it
+is being set by C<aio_readdirx>, when any of the C<$type>'s found were
+C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
+C<$type>'s are known, which can be used to speed up some algorithms.
+=back
 =item aio_load $path, $data, $callback->($status)
 This is a composite request that tries to fully load the given file into
 =item aio_copy $srcpath, $dstpath, $callback->($status)
 Try to copy the I<file> (directories not supported as either source or
 destination) from C<$srcpath> to C<$dstpath> and call the callback with
-the C<0> (error) or C<-1> ok.
+a status of C<0> (ok) or C<-1> (error, see C<$!>).
 This is a composite request that creates the destination file with
 mode 0200 and copies the contents of the source file into it using
 C<aio_sendfile>, followed by restoring atime, mtime, access mode and
 uid/gid, in that order.
    my $grp = aio_group $cb;
    aioreq_pri $pri;
    add $grp aio_open $src, O_RDONLY, 0, sub {
       if (my $src_fh = $_[0]) {
-         my @stat = stat $src_fh;
+         my @stat = stat $src_fh; # hmm, might block over nfs?
          aioreq_pri $pri;
          add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
             if (my $dst_fh = $_[0]) {
                aioreq_pri $pri;
                add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
                   if ($_[0] == $stat[7]) {
                      $grp->result (0);
                      close $src_fh;
-                     # those should not normally block. should. should.
+                     my $ch = sub {
-                     utime $stat[8], $stat[9], $dst;
+                        aioreq_pri $pri;
-                     chmod $stat[2] & 07777, $dst_fh;
+                        add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
-                     chown $stat[4], $stat[5], $dst_fh;
+                           aioreq_pri $pri;
+                           add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
+                              aioreq_pri $pri;
+                              add $grp aio_close $dst_fh;
+                           }
+                        };
+                     };
                      aioreq_pri $pri;
-                     add $grp aio_close $dst_fh;
+                     add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
+                        if ($_[0] < 0 && $! == ENOSYS) {
+                           aioreq_pri $pri;
+                           add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
+                        } else {
+                           $ch->();
+                        }
+                     };
                   } else {
                      $grp->result (-1);
                      close $src_fh;
                      close $dst_fh;
 =item aio_move $srcpath, $dstpath, $callback->($status)
 Try to move the I<file> (directories not supported as either source or
 destination) from C<$srcpath> to C<$dstpath> and call the callback with
-the C<0> (error) or C<-1> ok.
+a status of C<0> (ok) or C<-1> (error, see C<$!>).
 This is a composite request that tries to rename(2) the file first; if
 rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
 that is successful, unlinks the C<$srcpath>.
 Implementation notes.
 The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
+If readdir returns file type information, then this is used directly to
+find directories.
-After reading the directory, the modification time, size etc. of the
+Otherwise, after reading the directory, the modification time, size etc.
-directory before and after the readdir is checked, and if they match (and
+of the directory before and after the readdir is checked, and if they
-isn't the current time), the link count will be used to decide how many
+match (and isn't the current time), the link count will be used to decide
-entries are directories (if >= 2). Otherwise, no knowledge of the number
+how many entries are directories (if >= 2). Otherwise, no knowledge of the
-of subdirectories will be assumed.
+number of subdirectories will be assumed.
-Then entries will be sorted into likely directories (everything without
+Then entries will be sorted into likely directories a non-initial dot
-a non-initial dot currently) and likely non-directories (everything
+currently) and likely non-directories (see C<aio_readdirx>). Then every
-else). Then every entry plus an appended C</.> will be C<stat>'ed,
+entry plus an appended C</.> will be C<stat>'ed, likely directories first,
-likely directories first. If that succeeds, it assumes that the entry
+in order of their inode numbers. If that succeeds, it assumes that the
-is a directory or a symlink to directory (which will be checked
+entry is a directory or a symlink to directory (which will be checked
 seperately). This is often faster than stat'ing the entry itself because
 filesystems might detect the type of the entry without reading the inode
-data (e.g. ext2fs filetype feature).
+data (e.g. ext2fs filetype feature), even on systems that cannot return
+the filetype information on readdir.
 If the known number of directories (link count - 2) has been reached, the
 rest of the entries is assumed to be non-directories.
 This only works with certainty on POSIX (= UNIX) filesystems, which
       my $now = time;
       my $hash1 = join ":", (stat _)[0,1,3,7,9];
       # read the directory entries
       aioreq_pri $pri;
-      add $grp aio_readdir $path, sub {
+      add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
          my $entries = shift
             or return $grp->result ();
          # stat the dir another time
          aioreq_pri $pri;
             # take the slow route if anything looks fishy
             if ($hash1 ne $hash2 or (stat _)[9] == $now) {
                $ndirs = -1;
             } else {
                # if nlink == 2, we are finished
-               # on non-posix-fs's, we rely on nlink < 2
+               # for non-posix-fs's, we rely on nlink < 2
                $ndirs = (stat _)[3] - 2
                   or return $grp->result ([], $entries);
             }
-            # sort into likely dirs and likely nondirs
-            # dirs == files without ".", short entries first
-            $entries = [map $_->[0],
-                           sort { $b->[1] cmp $a->[1] }
-                              map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
-                                 @$entries];
             my (@dirs, @nondirs);
             my $statgrp = add $grp aio_group sub {
                $grp->result (\@dirs, \@nondirs);
             };
             limit $statgrp $maxreq;
             feed $statgrp sub {
                return unless @$entries;
-               my $entry = pop @$entries;
+               my $entry = shift @$entries;
                aioreq_pri $pri;
                add $statgrp aio_stat "$path/$entry/.", sub {
                   if ($_[0] < 0) {
                      push @nondirs, $entry;
 (E.g. rename). This might not work on all operating systems or have any
 specific effect, but usually it makes sure that directory changes get
 written to disc. It works for anything that can be opened for read-only,
 not just directories.
+Future versions of this function might fall back to other methods when
+C<fsync> on the directory fails (such as calling C<sync>).
 Passes C<0> when everything went ok, and C<-1> on error.
 =cut
 sub aio_pathsync($;$) {
    };
    $grp
 }
+=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
+This is a rather advanced IO::AIO call, which only works on mmap(2)ed
+scalars (see the C<IO::AIO::mmap> function, although it also works on data
+scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
+scalar must only be modified in-place while an aio operation is pending on
+it).
+It calls the C<msync> function of your OS, if available, with the memory
+area starting at C<$offset> in the string and ending C<$length> bytes
+later. If C<$length> is negative, counts from the end, and if C<$length>
+is C<undef>, then it goes till the end of the string. The flags can be
+a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
+C<IO::AIO::MS_SYNC>.
+=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
+This is a rather advanced IO::AIO call, which works best on mmap(2)ed
+scalars.
+It touches (reads or writes) all memory pages in the specified
+range inside the scalar.  All caveats and parameters are the same
+as for C<aio_msync>, above, except for flags, which must be either
+C<0> (which reads all pages and ensures they are instantiated) or
+C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
+writing an octet from it, which dirties the page).
+=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
+This is a rather advanced IO::AIO call, which works best on mmap(2)ed
+scalars.
+It reads in all the pages of the underlying storage into memory (if any)
+and locks them, so they are not getting swapped/paged out or removed.
+If C<$length> is undefined, then the scalar will be locked till the end.
+On systems that do not implement C<mlock>, this function returns C<-1>
+and sets errno to C<ENOSYS>.
+Note that the corresponding C<munlock> is synchronous and is
+documented under L<MISCELLANEOUS FUNCTIONS>.
+Example: open a file, mmap and mlock it - both will be undone when
+C<$data> gets destroyed.
+   open my $fh, "<", $path or die "$path: $!";
+   my $data;
+   IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
+   aio_mlock $data; # mlock in background
+=item aio_mlockall $flags, $callback->($status)
+Calls the C<mlockall> function with the given C<$flags> (a combination of
+C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
+On systems that do not implement C<mlockall>, this function returns C<-1>
+and sets errno to C<ENOSYS>.
+Note that the corresponding C<munlockall> is synchronous and is
+documented under L<MISCELLANEOUS FUNCTIONS>.
+Example: asynchronously lock all current and future pages into memory.
+   aio_mlockall IO::AIO::MCL_FUTURE;
 =item aio_group $callback->(...)
 This is a very special aio request: Instead of doing something, it is a
 container for other aio requests, which is useful if you want to bundle
 many requests into a single, composite, request with a definite callback
 =item cancel $req
 Cancels the request, if possible. Has the effect of skipping execution
 when entering the B<execute> state and skipping calling the callback when
 entering the the B<result> state, but will leave the request otherwise
-untouched. That means that requests that currently execute will not be
+untouched (with the exception of readdir). That means that requests that
-stopped and resources held by the request will not be freed prematurely.
+currently execute will not be stopped and resources held by the request
+will not be freed prematurely.
 =item cb $req $callback->(...)
 Replace (or simply set) the callback registered to the request.
 =item $grp->cancel_subs
 Cancel all subrequests and clears any feeder, but not the group request
 itself. Useful when you queued a lot of events but got a result early.
+The group request will finish normally (you cannot add requests to the
+group).
 =item $grp->result (...)
 Set the result value(s) that will be passed to the group callback when all
 subrequests have finished and set the groups errno to the current value
 =over 4
 =item $fileno = IO::AIO::poll_fileno
 Return the I<request result pipe file descriptor>. This filehandle must be
-polled for reading by some mechanism outside this module (e.g. Event or
+polled for reading by some mechanism outside this module (e.g. EV, Glib,
-select, see below or the SYNOPSIS). If the pipe becomes readable you have
+select and so on, see below or the SYNOPSIS). If the pipe becomes readable
-to call C<poll_cb> to check the results.
+you have to call C<poll_cb> to check the results.
 See C<poll_cb> for an example.
 =item IO::AIO::poll_cb
 If not all requests were processed for whatever reason, the filehandle
 will still be ready when C<poll_cb> returns, so normally you don't have to
 do anything special to have it called later.
 Example: Install an Event watcher that automatically calls
-IO::AIO::poll_cb with high priority:
+IO::AIO::poll_cb with high priority (more examples can be found in the
+SYNOPSIS section, at the top of this document):
    Event->io (fd => IO::AIO::poll_fileno,
               poll => 'r', async => 1,
               cb => \&IO::AIO::poll_cb);
+=item IO::AIO::poll_wait
+If there are any outstanding requests and none of them in the result
+phase, wait till the result filehandle becomes ready for reading (simply
+does a C<select> on the filehandle. This is useful if you want to
+synchronously wait for some requests to finish).
+See C<nreqs> for an example.
+=item IO::AIO::poll
+Waits until some requests have been handled.
+Returns the number of requests processed, but is otherwise strictly
+equivalent to:
+   IO::AIO::poll_wait, IO::AIO::poll_cb
+=item IO::AIO::flush
+Wait till all outstanding AIO requests have been handled.
+Strictly equivalent to:
+   IO::AIO::poll_wait, IO::AIO::poll_cb
+      while IO::AIO::nreqs;
 =item IO::AIO::max_poll_reqs $nreqs
 =item IO::AIO::max_poll_time $seconds
    # use a low priority so other tasks have priority
    Event->io (fd => IO::AIO::poll_fileno,
               poll => 'r', nice => 1,
               cb => &IO::AIO::poll_cb);
-=item IO::AIO::poll_wait
-If there are any outstanding requests and none of them in the result
-phase, wait till the result filehandle becomes ready for reading (simply
-does a C<select> on the filehandle. This is useful if you want to
-synchronously wait for some requests to finish).
-See C<nreqs> for an example.
-=item IO::AIO::poll
-Waits until some requests have been handled.
-Returns the number of requests processed, but is otherwise strictly
-equivalent to:
-   IO::AIO::poll_wait, IO::AIO::poll_cb
-=item IO::AIO::flush
-Wait till all outstanding AIO requests have been handled.
-Strictly equivalent to:
-   IO::AIO::poll_wait, IO::AIO::poll_cb
-      while IO::AIO::nreqs;
 =back
 =head3 CONTROLLING THE NUMBER OF THREADS
 =over
 Returns the number of requests currently in the pending state (executed,
 but not yet processed by poll_cb).
 =back
+=head3 MISCELLANEOUS FUNCTIONS
+IO::AIO implements some functions that might be useful, but are not
+asynchronous.
+=over 4
+=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
+Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
+but is blocking (this makes most sense if you know the input data is
+likely cached already and the output filehandle is set to non-blocking
+operations).
+Returns the number of bytes copied, or C<-1> on error.
+=item IO::AIO::fadvise $fh, $offset, $len, $advice
+Simply calls the C<posix_fadvise> function (see it's
+manpage for details). The following advice constants are
+avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
+C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
+C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
+On systems that do not implement C<posix_fadvise>, this function returns
+ENOSYS, otherwise the return value of C<posix_fadvise>.
+=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
+Memory-maps a file (or anonymous memory range) and attaches it to the
+given C<$scalar>, which will act like a string scalar.
+The only operations allowed on the scalar are C<substr>/C<vec> that don't
+change the string length, and most read-only operations such as copying it
+or searching it with regexes and so on.
+Anything else is unsafe and will, at best, result in memory leaks.
+The memory map associated with the C<$scalar> is automatically removed
+when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
+C<IO::AIO::munmap> functions are called.
+This calls the C<mmap>(2) function internally. See your system's manual
+page for details on the C<$length>, C<$prot> and C<$flags> parameters.
+The C<$length> must be larger than zero and smaller than the actual
+filesize.
+C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
+C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
+C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
+C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
+not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
+(which is set to C<MAP_ANON> if your system only provides this
+constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
+C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
+C<IO::AIO::MAP_NONBLOCK>
+If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
+C<$offset> is the offset from the start of the file - it generally must be
+a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
+Example:
+   use Digest::MD5;
+   use IO::AIO;
+   open my $fh, "<verybigfile"
+      or die "$!";
+   IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
+      or die "verybigfile: $!";
+   my $fast_md5 = md5 $data;
+=item IO::AIO::munmap $scalar
+Removes a previous mmap and undefines the C<$scalar>.
+=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
+Calls the C<munlock> function, undoing the effects of a previous
+C<aio_mlock> call (see its description for details).
+=item IO::AIO::munlockall
+Calls the C<munlockall> function.
+On systems that do not implement C<munlockall>, this function returns
+ENOSYS, otherwise the return value of C<munlockall>.
+=back
 =cut
 min_parallel 8;
 END { flush }
 1;
+=head1 EVENT LOOP INTEGRATION
+It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
+automatically into many event loops:
+ # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
+ use AnyEvent::AIO;
+You can also integrate IO::AIO manually into many event loops, here are
+some examples of how to do this:
+ # EV integration
+ my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
+ # Event integration
+ Event->io (fd => IO::AIO::poll_fileno,
+            poll => 'r',
+            cb => \&IO::AIO::poll_cb);
+ # Glib/Gtk2 integration
+ add_watch Glib::IO IO::AIO::poll_fileno,
+           in => sub { IO::AIO::poll_cb; 1 };
+ # Tk integration
+ Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
+                           readable => \&IO::AIO::poll_cb);
+ # Danga::Socket integration
+ Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
+                             \&IO::AIO::poll_cb);
 =head2 FORK BEHAVIOUR
 This module should do "the right thing" when the process using it forks:

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Revision 1.183 by root, Sun Sep 12 03:40:05 2010 UTC