code: @Override
      public void waitForRunningCommit() throws TTIOException {
          if (mCommitRunning != null) {
              try {
                  // long time = System.currentTimeMillis();
                  mCommitRunning.get();
                  // System.out.println(System.currentTimeMillis() - time);
                  mCommitRunning = null;
              } catch (InterruptedException | ExecutionException exc) {
                  throw new TTIOException(exc);
              }
          }
      }
docs: {@inheritDoc}