hadoop CumulativePeriodicStats 源码
haddop CumulativePeriodicStats 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/CumulativePeriodicStats.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 org.apache.hadoop.mapred;
/**
*
* This class is a concrete PeriodicStatsAccumulator that deals with
* measurements where the raw data are a measurement of an
* accumulation. The result in each bucket is the estimate
* of the progress-weighted change in that quantity over the
* progress range covered by the bucket.
*
* <p>An easy-to-understand example of this kind of quantity would be
* a distance traveled. It makes sense to consider that portion of
* the total travel that can be apportioned to each bucket.
*
*/
class CumulativePeriodicStats extends PeriodicStatsAccumulator {
// int's are acceptable here, even though times are normally
// long's, because these are a difference and an int won't
// overflow for 24 days. Tasks can't run for more than about a
// week for other reasons, and most jobs would be written
int previousValue = 0;
CumulativePeriodicStats(int count) {
super(count);
}
/**
*
* accumulates a new reading by keeping a running account of the
* value distance from the beginning of the bucket to the end of
* this reading
*/
@Override
protected void extendInternal(double newProgress, int newValue) {
if (state == null) {
return;
}
state.currentAccumulation += (double)(newValue - previousValue);
previousValue = newValue;
}
}
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