heron/api/src/java/com/twitter/heron/api/windowing/TupleFieldTimestampExtractor.java

//  Copyright 2017 Twitter. All rights reserved.
//
//  Licensed 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 com.twitter.heron.api.windowing;

import com.twitter.heron.api.tuple.Tuple;

/**
 * A {@link TimestampExtractor} that extracts timestamp from a specific field in the tuple.
 */
public final class TupleFieldTimestampExtractor implements TimestampExtractor {
  private static final long serialVersionUID = 6302970084936569305L;
  private final String fieldName;

  private TupleFieldTimestampExtractor(String fieldName) {
    this.fieldName = fieldName;
  }

  @Override
  public long extractTimestamp(Tuple tuple) {
    return tuple.getLongByField(fieldName);
  }

  public static TupleFieldTimestampExtractor of(String fieldName) {
    return new TupleFieldTimestampExtractor(fieldName);
  }

  @Override
  public String toString() {
    return "TupleFieldTimestampExtractor{" + "fieldName='" + fieldName + '\'' + '}';
  }
}