protected void notifyLocator(L locator){
synchronized (this) {
    if (!knownLocators.add(locator.getPartitionId())) {
      throw new IllegalStateException("Already located on this DS: " + locator);
    }
  }
}

protected void notifyLocator ( L locator ) { synchronized ( this ) { if ( ! knownLocators . add ( locator . getPartitionId ( ) ) ) { throw new IllegalStateException ( "Already located on this DS: " + locator ) ; } } }
notify the data service that an index partition is now located on that data service .
