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/* * Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. * A copy of the License is located at * * http://aws.amazon.com/apache2.0 * * or in the "license" file accompanying this file. This file 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 com.amazonaws.retry; import com.amazonaws.AmazonClientException; import com.amazonaws.AmazonServiceException; import com.amazonaws.AmazonWebServiceRequest; import com.amazonaws.ClientConfiguration; import java.io.IOException; /** * This class includes a set of pre-defined retry policies, including default * policies used by SDK. */ public class PredefinedRetryPolicies { /** No retry policy **/ public static final RetryPolicy NO_RETRY_POLICY = new RetryPolicy(RetryPolicy.RetryCondition.NO_RETRY_CONDITION, RetryPolicy.BackoffStrategy.NO_DELAY, 0, // maxErrorRetry false); // honorMaxErrorRetryInClientConfig /* SDK default */ /** SDK default max retry count **/ public static final int DEFAULT_MAX_ERROR_RETRY = 3; /** * SDK default retry policy. Amazon DynamoDB has a custom retry policy that is used when no * {@link ClientConfiguration} is provided. */ public static final RetryPolicy DEFAULT; /* Default for DynamoDB client */ /** Default max retry count for DynamoDB client **/ public static final int DYNAMODB_DEFAULT_MAX_ERROR_RETRY = 10; /** Default policy for DynamoDB client **/ public static final RetryPolicy DYNAMODB_DEFAULT; /* Reusable retry policy components */ /** * The SDK default retry condition, which checks for various conditions in * the following order: * <ul> * <li>Never retry on requests with non-repeatable content; * <li>Retry on client exceptions caused by IOException; * <li>Retry on service exceptions that are either 500 internal server * errors, 503 service unavailable errors, service throttling errors or * clock skew errors. * </ul> */ public static final RetryPolicy.RetryCondition DEFAULT_RETRY_CONDITION = new SDKDefaultRetryCondition(); /** * The SDK default back-off strategy, which increases exponentially up to a max amount of delay. It also applies a larger * scale factor upon service throttling exception. */ public static final RetryPolicy.BackoffStrategy DEFAULT_BACKOFF_STRATEGY = new PredefinedBackoffStrategies.SDKDefaultBackoffStrategy(); /** * The SDK default back-off strategy, which increases exponentially up to a max amount of delay. It also applies a larger * scale factor upon service throttling exception. */ public static final V2CompatibleBackoffStrategy DEFAULT_BACKOFF_STRATEGY_V2 = new PredefinedBackoffStrategies.SDKDefaultBackoffStrategy(); /** * The default back-off strategy for DynamoDB client, which increases * exponentially up to a max amount of delay. Compared to the SDK default * back-off strategy, it applies a smaller scale factor. */ public static final RetryPolicy.BackoffStrategy DYNAMODB_DEFAULT_BACKOFF_STRATEGY = new PredefinedBackoffStrategies.SDKDefaultBackoffStrategy( PredefinedBackoffStrategies.DYNAMODB_DEFAULT_BASE_DELAY, PredefinedBackoffStrategies.SDK_DEFAULT_THROTTLED_BASE_DELAY, PredefinedBackoffStrategies.SDK_DEFAULT_MAX_BACKOFF_IN_MILLISECONDS); static { DEFAULT = getDefaultRetryPolicy(); DYNAMODB_DEFAULT = getDynamoDBDefaultRetryPolicy(); } /** * Returns the SDK default retry policy. This policy will honor the * maxErrorRetry set in ClientConfiguration. * * @see ClientConfiguration#setMaxErrorRetry(int) */ public static RetryPolicy getDefaultRetryPolicy() { return new RetryPolicy(DEFAULT_RETRY_CONDITION, DEFAULT_BACKOFF_STRATEGY, DEFAULT_MAX_ERROR_RETRY, true); } /** * Returns the default retry policy for DynamoDB client. This policy will * honor the maxErrorRetry set in ClientConfiguration. * * @see ClientConfiguration#setMaxErrorRetry(int) */ public static RetryPolicy getDynamoDBDefaultRetryPolicy() { return new RetryPolicy(DEFAULT_RETRY_CONDITION, DYNAMODB_DEFAULT_BACKOFF_STRATEGY, DYNAMODB_DEFAULT_MAX_ERROR_RETRY, true); } /** * Returns the SDK default retry policy with the specified max retry count. */ public static RetryPolicy getDefaultRetryPolicyWithCustomMaxRetries(int maxErrorRetry) { return new RetryPolicy(DEFAULT_RETRY_CONDITION, DEFAULT_BACKOFF_STRATEGY, maxErrorRetry, false); } /** * Returns the default retry policy for DynamoDB client with the specified * max retry count. */ public static RetryPolicy getDynamoDBDefaultRetryPolicyWithCustomMaxRetries(int maxErrorRetry) { return new RetryPolicy(DEFAULT_RETRY_CONDITION, DYNAMODB_DEFAULT_BACKOFF_STRATEGY, maxErrorRetry, false); } /** * The default implementation of RetryCondition used by the SDK. User could * extend this class to provide additional custom conditions. * The default implementation checks for various conditions in * the following order: * <ul> * <li>Retry on client exceptions caused by IOException; * <li>Retry on service exceptions that are either 500 internal server * errors, 503 service unavailable errors, service throttling errors or * clock skew errors. * </ul> */ public static class SDKDefaultRetryCondition implements RetryPolicy.RetryCondition { @Override public boolean shouldRetry(AmazonWebServiceRequest originalRequest, AmazonClientException exception, int retriesAttempted) { // Always retry on client exceptions caused by IOException if (exception.getCause() instanceof IOException) return true; // Only retry on a subset of service exceptions if (exception instanceof AmazonServiceException) { AmazonServiceException ase = (AmazonServiceException) exception; /* * For 500 internal server errors and 503 service * unavailable errors, we want to retry, but we need to use * an exponential back-off strategy so that we don't overload * a server with a flood of retries. */ if (RetryUtils.isRetryableServiceException(ase)) return true; /* * Throttling is reported as a 400 error from newer services. To try * and smooth out an occasional throttling error, we'll pause and * retry, hoping that the pause is long enough for the request to * get through the next time. */ if (RetryUtils.isThrottlingException(ase)) return true; /* * Clock skew exception. If it is then we will get the time offset * between the device time and the server time to set the clock skew * and then retry the request. */ if (RetryUtils.isClockSkewError(ase)) return true; } return false; } } }