tle="Class template unlocked_sink">unlocked_sink</a></code>
          frontend performs no thread synchronization when accessing the backend,
          assuming that synchronization either is not needed or is implemented by
          the backend. Nevertheless, setting up a filter is still thread-safe (that
          is, one can safely change the filter in the <code class="computeroutput"><a class="link" href="../../boost/log/sinks/unlocked_sink.html" title="Class template unlocked_sink">unlocked_sink</a></c