com.twitter.heron.api.metric.ReducedMetric Maven / Gradle / Ivy
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// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
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//
// 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
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/**
* 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;
/**
* Apply an update to an metric using an IReducer for which a result can be extracted.
* @param accumulator to hold and update state
* @param type of input that can be handled
* @param type of reduced value
*/
public class ReducedMetric implements IMetric {
private final IReducer reducer;
private T accumulator;
public ReducedMetric(IReducer aReducer) {
reducer = aReducer;
accumulator = reducer.init();
}
public void update(U value) {
accumulator = reducer.reduce(accumulator, value);
}
@Override
public V getValueAndReset() {
V ret = reducer.extractResult(accumulator);
accumulator = reducer.init();
return ret;
}
}