common/src/main/java/org/apache/nemo/common/ir/vertex/transform/NoWatermarkEmitTransform.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.nemo.common.ir.vertex.transform;

import org.apache.nemo.common.punctuation.Watermark;

/**
 * This transform does not emit watermarks.
 * It may be a transform for batch operation that emits collected data when calling {@link Transform#close()}.
 *
 * @param <I> input type
 * @param <O> output type
 */
public abstract class NoWatermarkEmitTransform<I, O> implements Transform<I, O> {

  /**
   * @param watermark watermark
   */
  @Override
  public final void onWatermark(final Watermark watermark) {
    // do nothing
  }

}