org.springframework.cloud.aws.jdbc.retry

Class SqlRetryPolicy

java.lang.Object

org.springframework.cloud.aws.jdbc.retry.SqlRetryPolicy

All Implemented Interfaces:

org.springframework.retry.RetryPolicy

public class SqlRetryPolicy
extends Object
implements org.springframework.retry.RetryPolicy

RetryPolicy implementation that checks for database error which are retryable. Normally this are well known exceptions inside the JDBC (1.6) exception hierarchy and also the Spring DataAccessException hierarchy. In addition to that, this class also tries for permanent exception which are related to a connection of the database. This is useful because Amazon RDS database instances might be retryable even if there is a permanent error. This is typically the case in a master a/z failover where the source instance might not be available but a second attempt might succeed because the DNS record has been updated to the failover instance.

In contrast to a SimpleRetryPolicy this class also checks recursively the cause of the exception if there is a retryable implementation.

Since:

1.0

Author:

Agim Emruli

Constructor Summary

Constructors

Constructor and Description
SqlRetryPolicy()

Method Summary

Modifier and Type	Method and Description
boolean	canRetry(org.springframework.retry.RetryContext context) Returns if this method is retryable based on the RetryContext.
void	close(org.springframework.retry.RetryContext context)
org.springframework.retry.RetryContext	open(org.springframework.retry.RetryContext parent)
void	registerThrowable(org.springframework.retry.RetryContext context, Throwable throwable)
void	setMaxNumberOfRetries(int maxNumberOfRetries) Configures the maximum number of retries.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SqlRetryPolicy

public SqlRetryPolicy()

Method Detail

canRetry

public boolean canRetry(org.springframework.retry.RetryContext context)

Returns if this method is retryable based on the RetryContext. If there is no Throwable registered, then this method returns true without checking any further conditions. If there is a Throwable registered, this class checks if the registered Throwable is a retryable Exception in the context of SQL exception. If not successful, this class also checks the cause if there is a nested retryable exception available.

Before checking exception this class checks that the current retry count (fetched through RetryContext.getRetryCount() is smaller or equals to the maxNumberOfRetries

Specified by:

canRetry in interface org.springframework.retry.RetryPolicy

Parameters:

context - - the retry context holding information about the retryable operation (number of retries, throwable if any)

Returns:

true if there is no throwable registered, if there is a retryable exception and the number of maximum numbers of retries have not been reached.

open

public org.springframework.retry.RetryContext open(org.springframework.retry.RetryContext parent)

Specified by:

open in interface org.springframework.retry.RetryPolicy

close

public void close(org.springframework.retry.RetryContext context)

Specified by:

close in interface org.springframework.retry.RetryPolicy

registerThrowable

public void registerThrowable(org.springframework.retry.RetryContext context,
                              Throwable throwable)

Specified by:

registerThrowable in interface org.springframework.retry.RetryPolicy

setMaxNumberOfRetries

public void setMaxNumberOfRetries(int maxNumberOfRetries)

Configures the maximum number of retries. This number should be a trade-off between having enough retries to survive a database outage due to failure and a responsive and not stalling application. The default value for the maximum number is 3.

Note:Consider using a BackOffPolicy which ensures that there is enough time left between the retry attempts instead of increasing this value to a high number. The back-off policy ensures that there is a delay in between the retry operations.

Parameters:

maxNumberOfRetries - - the maximum number of retries should be a positive number, otherwise all retries will fail.