| /** |
| * 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; |
| } |
| |
| |
| } |
| } |