org.apache.hudi.org.apache.hadoop.hbase.util.WeightedMovingAverage Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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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,
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* See the License for the specific language governing permissions and
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*/
package org.apache.hadoop.hbase.util;
import org.apache.yetus.audience.InterfaceAudience;
/**
* Different from SMA {@link SimpleMovingAverage}, WeightedMovingAverage gives each data different
* weight. And it is based on {@link WindowMovingAverage}, such that it only focus on the last N.
*/
@InterfaceAudience.Private
public class WeightedMovingAverage extends WindowMovingAverage {
private int[] coefficient;
private int denominator;
public WeightedMovingAverage(String label) {
this(label, DEFAULT_SIZE);
}
public WeightedMovingAverage(String label, int size) {
super(label, size);
int length = getNumberOfStatistics();
denominator = length * (length + 1) / 2;
coefficient = new int[length];
// E.g. default size is 5, coefficient should be [1, 2, 3, 4, 5]
for (int i = 0; i < length; i++) {
coefficient[i] = i + 1;
}
}
@Override
public double getAverageTime() {
if (!enoughStatistics()) {
return super.getAverageTime();
}
// only we get enough statistics, then start WMA.
double average = 0.0;
int coIndex = 0;
int length = getNumberOfStatistics();
// tmIndex, it points to the oldest data.
for (int tmIndex = (getMostRecentPosistion() + 1) % length;
coIndex < length;
coIndex++, tmIndex = (++tmIndex) % length) {
// start the multiplication from oldest to newest
average += coefficient[coIndex] * getStatisticsAtIndex(tmIndex);
}
return average / denominator;
}
}