| /** |
| * 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.azurebfs.services; |
| |
| import java.util.Random; |
| import java.net.HttpURLConnection; |
| |
| /** |
| * Retry policy used by AbfsClient. |
| * */ |
| public class ExponentialRetryPolicy { |
| /** |
| * Represents the default amount of time used when calculating a random delta in the exponential |
| * delay between retries. |
| */ |
| private static final int DEFAULT_CLIENT_BACKOFF = 1000 * 3; |
| |
| /** |
| * Represents the default maximum amount of time used when calculating the exponential |
| * delay between retries. |
| */ |
| private static final int DEFAULT_MAX_BACKOFF = 1000 * 30; |
| |
| /** |
| * Represents the default minimum amount of time used when calculating the exponential |
| * delay between retries. |
| */ |
| private static final int DEFAULT_MIN_BACKOFF = 1000 * 3; |
| |
| /** |
| * The minimum random ratio used for delay interval calculation. |
| */ |
| private static final double MIN_RANDOM_RATIO = 0.8; |
| |
| /** |
| * The maximum random ratio used for delay interval calculation. |
| */ |
| private static final double MAX_RANDOM_RATIO = 1.2; |
| |
| /** |
| * Holds the random number generator used to calculate randomized backoff intervals |
| */ |
| private final Random randRef = new Random(); |
| |
| /** |
| * The value that will be used to calculate a random delta in the exponential delay interval |
| */ |
| private final int deltaBackoff; |
| |
| /** |
| * The maximum backoff time. |
| */ |
| private final int maxBackoff; |
| |
| /** |
| * The minimum backoff time. |
| */ |
| private final int minBackoff; |
| |
| /** |
| * The maximum number of retry attempts. |
| */ |
| private final int retryCount; |
| |
| /** |
| * Initializes a new instance of the {@link ExponentialRetryPolicy} class. |
| */ |
| public ExponentialRetryPolicy(final int maxIoRetries) { |
| |
| this(maxIoRetries, DEFAULT_MIN_BACKOFF, DEFAULT_MAX_BACKOFF, |
| DEFAULT_CLIENT_BACKOFF); |
| } |
| |
| /** |
| * Initializes a new instance of the {@link ExponentialRetryPolicy} class. |
| * |
| * @param retryCount The maximum number of retry attempts. |
| * @param minBackoff The minimum backoff time. |
| * @param maxBackoff The maximum backoff time. |
| * @param deltaBackoff The value that will be used to calculate a random delta in the exponential delay |
| * between retries. |
| */ |
| public ExponentialRetryPolicy(final int retryCount, final int minBackoff, final int maxBackoff, final int deltaBackoff) { |
| this.retryCount = retryCount; |
| this.minBackoff = minBackoff; |
| this.maxBackoff = maxBackoff; |
| this.deltaBackoff = deltaBackoff; |
| } |
| |
| /** |
| * Returns if a request should be retried based on the retry count, current response, |
| * and the current strategy. |
| * |
| * @param retryCount The current retry attempt count. |
| * @param statusCode The status code of the response, or -1 for socket error. |
| * @return true if the request should be retried; false otherwise. |
| */ |
| public boolean shouldRetry(final int retryCount, final int statusCode) { |
| return retryCount < this.retryCount |
| && (statusCode == -1 |
| || statusCode == HttpURLConnection.HTTP_CLIENT_TIMEOUT |
| || (statusCode >= HttpURLConnection.HTTP_INTERNAL_ERROR |
| && statusCode != HttpURLConnection.HTTP_NOT_IMPLEMENTED |
| && statusCode != HttpURLConnection.HTTP_VERSION)); |
| } |
| |
| /** |
| * Returns backoff interval between 80% and 120% of the desired backoff, |
| * multiply by 2^n-1 for exponential. |
| * |
| * @param retryCount The current retry attempt count. |
| * @return backoff Interval time |
| */ |
| public long getRetryInterval(final int retryCount) { |
| final long boundedRandDelta = (int) (this.deltaBackoff * MIN_RANDOM_RATIO) |
| + this.randRef.nextInt((int) (this.deltaBackoff * MAX_RANDOM_RATIO) |
| - (int) (this.deltaBackoff * MIN_RANDOM_RATIO)); |
| |
| final double incrementDelta = (Math.pow(2, retryCount - 1)) * boundedRandDelta; |
| |
| final long retryInterval = (int) Math.round(Math.min(this.minBackoff + incrementDelta, maxBackoff)); |
| |
| return retryInterval; |
| } |
| } |