/*
* Copyright 2010-2017 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 (except for AmazonDynamoDBClient,
* whose constructor will replace the DEFAULT with DYNAMODB_DEFAULT.)
*/
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;
}
}
}