--- IO-AIO/AIO.pm	2007/10/03 21:27:51	1.116
+++ IO-AIO/AIO.pm	2007/10/06 14:05:19	1.117
@@ -185,13 +185,15 @@
 
 package IO::AIO;
 
+use Carp ();
+
 no warnings;
 use strict 'vars';
 
 use base 'Exporter';
 
 BEGIN {
-   our $VERSION = '2.5';
+   our $VERSION = '2.51';
 
    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_scandir aio_symlink
@@ -315,17 +317,65 @@
 Asynchronously close a file and call the callback with the result
 code.
 
-Unlike the other functions operating on files, this function uses the
-PerlIO layer to close the filehandle. The reason is that the PerlIO API
-insists on closing the underlying fd itself, no matter what, and doesn't
-allow modifications to the fd. Unfortunately, it is not clear that you can
-call PerlIO from different threads (actually, its quite clear that this
-won't work in some cases), so while it likely works perfectly with simple
-file handles (such as the ones created by C<aio_open>) it might fail in
-interesting ways for others.
+Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
+closing the file descriptor associated with the filehandle itself. Here is
+what aio_close will try:
+
+   1. dup()licate the fd
+   2. asynchronously close() the duplicated fd
+   3. dup()licate the fd once more
+   4. let perl close() the filehandle
+   5. asynchronously close the duplicated fd
+
+The idea is that the first close() flushes stuff to disk that closing an
+fd will flush, so when perl closes the fd, nothing much will need to be
+flushed.  The second async. close() will then flush stuff to disk that
+closing the last fd to the file will flush.
+
+Just FYI, SuSv3 has this to say on close:
+
+   All outstanding record locks owned by the process on the file
+   associated with the file descriptor shall be removed.
+
+   If fildes refers to a socket, close() shall cause the socket to be
+   destroyed. ... close() shall block for up to the current linger
+   interval until all data is transmitted.
+   [this actually sounds like a specification bug, but who knows]
+
+And at least Linux additionally actually flushes stuff on every close,
+even when the file itself is still open.
+
+Sounds enourmously inefficient and complicated? Yes... please show me how
+to nuke perl's fd out of existence...
+
+=cut
+
+sub aio_close($;$) {
+   aio_block {
+      my ($fh, $cb) = @_;
+
+      my $pri = aioreq_pri;
+      my $grp = aio_group $cb;
+
+      my $fd = fileno $fh;
+
+      defined $fd or Carp::croak "aio_close called with fd-less filehandle";
+
+      # if the dups fail we will simply get EBADF
+      my $fd2 = _dup $fd;
+      aioreq_pri $pri;
+      add $grp _aio_close $fd2, sub {
+         my $fd2 = _dup $fd;
+         close $fh;
+         aioreq_pri $pri;
+         add $grp _aio_close $fd2, sub {
+            $grp->result ($_[0]);
+         };
+      };
 
-Having said that, aio_close tries to clean up the filehandle as much as
-possible before handing it to an io thread, and generally does work.
+      $grp
+   }
+}
 
 
 =item aio_read  $fh,$offset,$length, $data,$dataoffset, $callback->($retval)