public void setReadLatch(CountDownLatch latch) {
    readLatch = latch;
  }
Sets the {@link CountDownLatch} for read, which will be counted down for each time {@link #get(String, Stat, int)}
is called. This is not thread safe.
@return The count of reads.
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixPropertyStore.java