Mastering Spring Retry for Effective Application Resilience
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Chapter 1: Introduction to Spring Retry
Spring Retry is a valuable feature within the Spring framework designed for method invocation retries. Built on Spring AOP, it effectively addresses method call failures that may arise from network issues or other unforeseen circumstances encountered in real-world applications.
The fundamental principle of Spring Retry is to attempt method calls again based on a specified retry strategy when they encounter failures. This strategy is defined through the RetryPolicy interface, which encompasses conditions for triggering retries, the exceptions that can initiate a retry, and the delay duration before subsequent attempts. Spring Retry supports various retry strategies, including BackOffPolicy.
Additionally, Spring Retry facilitates the use of direct method annotations via @Retryable, where users can configure relevant parameters. The RetryTemplate offers enhanced flexibility for managing retries, allowing for the implementation of custom retry logic. By utilizing the RetryCallback interface, developers can create callback methods for more control.
Chapter 2: Practical Applications
Section 2.1: Using Annotations
To use Spring Retry, first, add the necessary dependency:
org.springframework.retry
spring-retry
Entity Class and Repository Example:
@Entity
@Table(name = "t_account")
public class Account {
@Id
private Long id;
private String userId;
private BigDecimal money;
}
public interface AccountRepository extends JpaRepository<Account, Long> {
Account findByUserId(String userId);
}
Service Class Implementation:
@Service
public class AccountService {
@Resource
private AccountRepository accountRepository;
@Transactional
@Retryable(value = {InvalidParameterException.class})
public Account save(Account account) {
System.out.println(Thread.currentThread().getName());
if (account.getId() == 0) {
System.out.println("Attempting to save...");
throw new InvalidParameterException("Invalid parameter");
}
return accountRepository.saveAndFlush(account);
}
@Recover
public Account recoverSave(Exception e) {
System.out.println("Recovery initiated: " + e.getMessage());
return null;
}
}
Explanation of @Retryable Annotation:
- recover: Indicates the fallback method name; defaults to the method marked with @Recover.
- interceptor: Designates the method aspect bean.
- value / include: Types of exceptions that will trigger retries.
- exclude: Specifies exceptions that should not initiate a retry.
- label: A unique identifier for tracking.
- stateful: Defaults to false; indicates if the retry is stateful.
- maxAttempts: Defines the maximum number of retries, defaulting to 3.
- backoff: Specifies the backoff strategy through @Backoff attributes.
To enable the retry feature, configure it as follows:
@Configuration
@EnableRetry
public class RetryConfig {
}
Test Example:
@Resource
private AccountService accountService;
@Test
public void testSave() {
Account account = new Account();
account.setId(0L);
account.setMoney(BigDecimal.valueOf(1000));
account.setUserId("1");
accountService.save(account);
}
Console Output:
main
Attempting to save...
Attempting to save...
Attempting to save...
Retries exhausted...
Defaulted to 3 retries.
Using Listeners in @Retryable:
@Retryable(value = {InvalidParameterException.class}, stateful = false, listeners = {"accountRetryListener"})
public class AccountRetryListener implements RetryListener {
@Override
public boolean open(RetryContext context, RetryCallback callback) {
System.out.println("Opening retry context...");
return false;
}
@Override
public void close(RetryContext context, RetryCallback callback, Throwable throwable) {
System.out.println("Closing retry context...");}
@Override
public void onError(RetryContext context, RetryCallback callback, Throwable throwable) {
System.out.println("Error occurred: " + throwable.getMessage());}
}
If the open method returns false, no retries will be executed.
Execution Result:
Opening retry context...
main
Attempting to save...
Error occurred: Invalid parameter
main
Attempting to save...
Error occurred: Invalid parameter
main
Attempting to save...
Error occurred: Invalid parameter
Section 2.2: Programmatic Retry
To create a custom RetryTemplate, set it up like this:
@Configuration
@EnableRetry
public class RetryConfig {
@Bean
public RetryTemplate retryTemplate() {
return RetryTemplate.builder()
.maxAttempts(3)
.fixedBackoff(1000)
.retryOn(InvalidParameterException.class)
.build();
}
}
Update the service to use the RetryTemplate:
public class AccountService {
@Resource
private AccountRepository accountRepository;
@Resource
private RetryTemplate retryTemplate;
@Transactional
public Account update(Account account) {
return retryTemplate.execute(context -> {
if (account.getId() == 0) {
System.out.println("Attempting to update...");
throw new InvalidParameterException("Invalid parameter");
}
return accountRepository.saveAndFlush(account);
}, context -> {
System.out.println("Update attempts finished...");
return null;
});
}
}
Test Example:
@Test
public void testUpdate() {
Account account = new Account();
account.setId(0L);
account.setMoney(BigDecimal.valueOf(1000));
account.setUserId("1");
accountService.update(account);
}
Execution Result:
Attempting to update...
Attempting to update...
Attempting to update...
Update attempts finished...
To conclude, these advanced techniques and configurations for Spring Retry can significantly enhance application resilience, ensuring robust performance in the face of errors.
This video, titled "Spring Retry for resilient database or REST API access with simple annotation in Spring Boot," provides insightful guidance on implementing Spring Retry effectively.
Unlock the potential of Spring Boot Retry with this video, "Unlock the Hidden Power of Spring Boot Retry," which delves deeper into advanced retry strategies.