use DiskCache;
  my $xdc = new DiskCache "image", 300;

  if ( $xdc->exists( "filename.ext" ) ) {
    print $xdc->get( "filename.ext" );
  } else {
    $xdc->del( "filename.ext" );
    my $newdata = GetDataFromSomeWhere();
    print $newdata;
    $xdc->put( "filename.ext", $newdata );
  }