hadoop RollingWindowAverage 源码
haddop RollingWindowAverage 代码
文件路径：/hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/metrics/RollingWindowAverage.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.fs.azure.metrics;
import java.util.ArrayDeque;
import java.util.Date;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* Helper class to calculate rolling-window averages.
* Used to calculate rolling-window metrics in AzureNativeFileSystem.
*/
@InterfaceAudience.Private
final class RollingWindowAverage {
private final ArrayDeque<DataPoint> currentPoints =
new ArrayDeque<DataPoint>();
private final long windowSizeMs;
/**
* Create a new rolling-window average for the given window size.
* @param windowSizeMs The size of the window in milliseconds.
*/
public RollingWindowAverage(long windowSizeMs) {
this.windowSizeMs = windowSizeMs;
}
/**
* Add a new data point that just happened.
* @param value The value of the data point.
*/
public synchronized void addPoint(long value) {
currentPoints.offer(new DataPoint(new Date(), value));
cleanupOldPoints();
}
/**
* Get the current average.
* @return The current average.
*/
public synchronized long getCurrentAverage() {
cleanupOldPoints();
if (currentPoints.isEmpty()) {
return 0;
}
long sum = 0;
for (DataPoint current : currentPoints) {
sum += current.getValue();
}
return sum / currentPoints.size();
}
/**
* Clean up points that don't count any more (are before our
* rolling window) from our current queue of points.
*/
private void cleanupOldPoints() {
Date cutoffTime = new Date(new Date().getTime() - windowSizeMs);
while (!currentPoints.isEmpty()
&& currentPoints.peekFirst().getEventTime().before(cutoffTime)) {
currentPoints.removeFirst();
}
}
/**
* A single data point.
*/
private static class DataPoint {
private final Date eventTime;
private final long value;
public DataPoint(Date eventTime, long value) {
this.eventTime = eventTime;
this.value = value;
}
public Date getEventTime() {
return eventTime;
}
public long getValue() {
return value;
}
}
}
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