heron/api/src/java/com/twitter/heron/api/metric/CombinedMetric.java

// Copyright 2016 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.metric;

public class CombinedMetric<T> implements IMetric<T> {
  private final ICombiner<T> combiner;
  private T value;

  public CombinedMetric(ICombiner<T> aCombiner) {
    combiner = aCombiner;
    value = combiner.identity();
  }

  public void update(T aValue) {
    value = combiner.combine(value, aValue);
  }

  @Override
  public T getValueAndReset() {
    T ret = value;
    value = combiner.identity();
    return ret;
  }
}