storm-compatibility/src/java/backtype/storm/metric/api/CombinedMetric.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 backtype.storm.metric.api;

@SuppressWarnings({"rawtypes", "unchecked"})
public class CombinedMetric implements IMetric {
  private final ICombiner combiner;
  private Object value;

  public CombinedMetric(ICombiner combiner) {
    this.combiner = combiner;
    this.value = this.combiner.identity();
  }

  public void update(Object newValue) {
    value = combiner.combine(value, newValue);
  }

  public Object getValueAndReset() {
    Object ret = value;
    value = combiner.identity();
    return ret;
  }
}