+ my $file = $cache_file_name;
+ open ($cache_fd, '+>>', $file) || error ("unable to write $file: $!");
+ flock ($cache_fd, LOCK_EX) || error ("unable to lock $file: $!");
+ seek ($cache_fd, 0, 0) || error ("unable to rewind $file: $!");
+
+ my $mtime = (stat($cache_fd))[9];