@Override
  public void execute(Tuple tuple, BasicOutputCollector collector) {
    TransactionAttempt attempt = (TransactionAttempt) tuple.getValue(0);

    if (tuple.getSourceStreamId().equals(MasterBatchCoordinator.SUCCESS_STREAM_ID)) {
      _state.cleanupBefore(attempt.getTransactionId());
      _coord.success(attempt.getTransactionId());
    } else {
      long txid = attempt.getTransactionId();
      Object prevMeta = _state.getPreviousState(txid);
      Object meta = _coord.initializeTransaction(txid, prevMeta, _state.getState(txid));
      _state.overrideState(txid, meta);
      collector.emit(MasterBatchCoordinator.BATCH_STREAM_ID, new Values(attempt, meta));
    }
  }