private void instrument(Counter counter, Timer timer, Func0 func) {
    incCounter(counter);
    long startNs = clock.nanoTime();
    func.apply();
    updateTimer(timer, clock.nanoTime() - startNs);
  }
Refer to {@link KeyValueStore#all()}

@return an iterator for all entries in this key-value store.
samza-kv/src/main/java/org/apache/samza/storage/kv/LocalTable.java