Spring 7 RetryListener

by

Summary

The Spring 7 RetryListener is used to log every failure that will be retried, including the actual retry count. However, the actual retry count is only present in the RetryState, which is accessible in the onRetryableExecution(...) method. This method does not know if the failure will be retried. On the other hand, the beforeRetry(...) method knows that a retry will be called, but it does not have access to the RetryState.

Root Cause

The root cause of this issue is the design of the Spring 7 RetryListener interface, which does not provide a straightforward way to access the actual retry count in the beforeRetry(...) method. The causes of this issue include:

  • The RetryState is only accessible in the onRetryableExecution(...) method
  • The beforeRetry(...) method does not have access to the RetryState
  • The actual retry count is not directly available in the beforeRetry(...) method

Why This Happens in Real Systems

This issue occurs in real systems because the Spring 7 RetryListener is designed to provide a way to listen to retry events, but it does not provide a complete view of the retry state. The reasons for this include:

  • The RetryListener interface is designed to be flexible and extensible
  • The RetryState is an internal implementation detail of the RetryTemplate
  • The actual retry count is not always available or relevant in all retry scenarios

Real-World Impact

The impact of this issue in real-world systems includes:

  • Inability to track retry events with accurate retry counts
  • Difficulty in debugging retry-related issues
  • Inadequate logging of retry events, making it hard to diagnose problems

Example or Code

import org.springframework.core.retry.RetryListener;
import org.springframework.core.retry.RetryContext;

public class CustomRetryListener implements RetryListener {
    @Override
    public  boolean open(RetryContext context, RetryCallback callback) {
        return true;
    }

    @Override
    public  void onClose(RetryContext context, RetryCallback callback, Throwable throwable) {
        // Log retry event with actual retry count
    }

    @Override
    public  void onRetry(RetryContext context, RetryCallback callback, Throwable throwable) {
        // Log retry event with actual retry count
    }
}

How Senior Engineers Fix It

Senior engineers fix this issue by:

  • Implementing a custom RetryListener that tracks the retry count internally
  • Using a wrapper class to provide access to the RetryState in the beforeRetry(...) method
  • Modifying the RetryTemplate to provide a way to access the actual retry count in the beforeRetry(...) method

Why Juniors Miss It

Junior engineers may miss this issue because:

  • They may not fully understand the Spring 7 RetryListener interface and its limitations
  • They may not be aware of the internal implementation details of the RetryTemplate
  • They may not have experience with customizing the RetryListener to track retry events with accurate retry counts

Leave a Comment