storm-compatibility/src/java/backtype/storm/metric/api/ReducedMetric.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 ReducedMetric implements IMetric {
  private final IReducer reducer;
  private Object accumulator;

  public ReducedMetric(IReducer reducer) {
    this.reducer = reducer;
    this.accumulator = this.reducer.init();
  }

  public void update(Object value) {
    accumulator = reducer.reduce(accumulator, value);
  }

  public Object getValueAndReset() {
    Object ret = reducer.extractResult(accumulator);
    accumulator = reducer.init();
    return ret;
  }
}