com.twitter.heron.api.metric.MultiReducedMetric Maven / Gradle / Ivy

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// 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.

/**
 * 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 com.twitter.heron.api.metric;

import java.util.HashMap;
import java.util.Map;

/*
 * A reduce metric that can hold multiple scoped values.
 * @param  accumulator to hold and update state
 * @param  type of input that can be handled
 * @param  type of reduced value
 */
public class MultiReducedMetric implements IMetric> {
  private Map> value = new HashMap<>();
  private IReducer reducer;

  public MultiReducedMetric(IReducer reducer) {
    this.reducer = reducer;
  }

  public ReducedMetric scope(String key) {
    if (value.get(key) == null) {
      value.put(key, new ReducedMetric<>(reducer));
    }
    return value.get(key);
  }

  @Override
  public Map getValueAndReset() {
    Map ret = new HashMap<>();
    for (String key : value.keySet()) {
      V val = value.get(key).getValueAndReset();
      if (val != null) {
        ret.put(key, val);
      }
    }
    return ret;
  }
}