private boolean remove(GetOperation op) {
    if (getOperations.remove(op)) {
      routerMetrics.operationDequeuingRate.mark();
      return true;
    } else {
      return false;
    }
  }
Remove the operation from the set of operations handled by the GetManager.
This can potentially be called concurrently for the same operation, which is fine.
@param op the {@link GetOperation} to remove.
@return true if the operation was removed in this call.
ambry-router/src/main/java/com/github/ambry/router/GetManager.java