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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.AmazonWebServiceRequest; import com.amazonaws.ClientConfiguration; import com.amazonaws.annotation.Immutable; /** * Retry policy that can be configured on a specific service client using * {@link ClientConfiguration}. This class is immutable, therefore safe to be * shared by multiple clients. * * @see ClientConfiguration * @see PredefinedRetryPolicies */ @Immutable public final class RetryPolicy { /** * Condition on whether a request should be retried. This field * should not be null. */ private final RetryCondition retryCondition; /** * Back-off strategy to control the sleep time between retry attempts. This * field should not be null. */ private final BackoffStrategy backoffStrategy; /** * Non-negative integer indicating the max retry count. */ private final int maxErrorRetry; /** * Whether this retry policy should honor the max error retry set in ClientConfiguration. * @see ClientConfiguration#setMaxErrorRetry(int) */ private final boolean honorMaxErrorRetryInClientConfig; /** * Constructs a new retry policy. See {@link PredefinedRetryPolicies} for * some pre-defined policy components, and also the default policies used by * SDK. * * @param retryCondition * Retry condition on whether a specific request and exception * should be retried. If null value is specified, the SDK' * default retry condition is used. * @param backoffStrategy * Back-off strategy for controlling how long the next retry * should wait. If null value is specified, the SDK' default * exponential back-off strategy is used. * @param maxErrorRetry * Maximum number of retry attempts for failed requests. * @param honorMaxErrorRetryInClientConfig * Whether this retry policy should honor the max error retry set * by {@link ClientConfiguration#setMaxErrorRetry(int)} * @see ClientConfiguration * @see PredefinedRetryPolicies */ public RetryPolicy(RetryCondition retryCondition, BackoffStrategy backoffStrategy, int maxErrorRetry, boolean honorMaxErrorRetryInClientConfig) { if (retryCondition == null) { retryCondition = PredefinedRetryPolicies.DEFAULT_RETRY_CONDITION; } if (backoffStrategy == null) { backoffStrategy = PredefinedRetryPolicies.DEFAULT_BACKOFF_STRATEGY; } if (maxErrorRetry < 0) { throw new IllegalArgumentException("Please provide a non-negative value for maxErrorRetry."); } this.retryCondition = retryCondition; this.backoffStrategy = backoffStrategy; this.maxErrorRetry = maxErrorRetry; this.honorMaxErrorRetryInClientConfig = honorMaxErrorRetryInClientConfig; }; /** * Returns the retry condition included in this retry policy. * * @return The retry condition included in this retry policy. */ public RetryCondition getRetryCondition() { return retryCondition; } /** * Returns the back-off strategy included in this retry policy. * * @return The back-off strategy included in this retry policy. */ public BackoffStrategy getBackoffStrategy() { return backoffStrategy; } /** * Returns the maximum number of retry attempts. * * @return The maximum number of retry attempts. */ public int getMaxErrorRetry() { return maxErrorRetry; } /** * Returns whether this retry policy should honor the max error retry set in * ClientConfiguration. * * @return Whether this retry policy should honor the max error retry set in * ClientConfiguration * @see ClientConfiguration#setMaxErrorRetry(int) */ public boolean isMaxErrorRetryInClientConfigHonored() { return honorMaxErrorRetryInClientConfig; } /** * The hook for providing custom condition on whether a failed request * should be retried. */ public interface RetryCondition { RetryCondition NO_RETRY_CONDITION = new RetryCondition() { @Override public boolean shouldRetry(AmazonWebServiceRequest originalRequest, AmazonClientException exception, int retriesAttempted) { return false; } }; /** * Returns whether a failed request should be retried according to the * given request context. In the following circumstances, the request * will fail directly without consulting this method: * <ul> * <li> if it has already reached the max retry limit, * <li> if the request contains non-repeatable content, * <li> if any RuntimeException or Error is thrown when executing the request. * </ul> * * @param originalRequest * The original request object being executed. For * performance reason, this object is not a defensive copy, * and caller should not attempt to modify its data. * @param exception * The exception from the failed request, represented as an * AmazonClientException object. There are two types of * exception that will be passed to this method: * <ul> * <li>AmazonServiceException (sub-class of * AmazonClientException) indicating a service error * <li>AmazonClientException caused by an IOException when * executing the HTTP request. * </ul> * Any other exceptions are regarded as unexpected failures * and are thrown immediately without any retry. For * performance reason, this object is not a defensive copy, * and caller should not attempt to modify its data. * @param retriesAttempted * The number of times the current request has been * attempted. * * @return True if the failed request should be retried. */ boolean shouldRetry(AmazonWebServiceRequest originalRequest, AmazonClientException exception, int retriesAttempted); } /** * The hook for providing custom back-off strategy to control the sleep time * between retries. */ public interface BackoffStrategy { RetryPolicy.BackoffStrategy NO_DELAY = new BackoffStrategy() { @Override public long delayBeforeNextRetry(AmazonWebServiceRequest originalRequest, AmazonClientException exception, int retriesAttempted) { return 0; } }; /** * Returns the delay (in milliseconds) before next retry attempt. * * @param originalRequest * The original request object being executed. For * performance reason, this object is not a defensive copy, * and caller should not attempt to modify its data. * @param exception * The exception from the failed request, represented as an * AmazonClientException object. There are two types of * exception that will be passed to this method: * <ul> * <li>AmazonServiceException (sub-class of * AmazonClientException) indicating a service error * <li>AmazonClientException caused by an IOException when * executing the HTTP request. * </ul> * Any other exceptions are regarded as unexpected failures * and are thrown immediately without any retry. For * performance reason, this object is not a defensive copy, * and caller should not attempt to modify its data. * @param retriesAttempted * The number of times the current request has been attempted * (not including the next attempt after the delay). * * @return The delay (in milliseconds) before next retry attempt. */ long delayBeforeNextRetry(AmazonWebServiceRequest originalRequest, AmazonClientException exception, int retriesAttempted); } }