class MetricsSystemImpl extends MetricsSystem implements MetricsSource {

  @Override public synchronized
  void unregisterSource(String name) {
    if (sources.containsKey(name)) {
      sources.get(name).stop();
      sources.remove(name);
    }
    if (allSources.containsKey(name)) {
      allSources.remove(name);
    }
    if (namedCallbacks.containsKey(name)) {
      namedCallbacks.remove(name);
    }
  }

  public  MetricsSystemImpl(String prefix);
  public  MetricsSystemImpl();

}