Over the past few months, I have been dealing with caching in Spring Boot, actively using it in many projects. This has given me the opportunity to delve into the Spring Cache Abstraction, understanding its strengths and weaknesses.

Generally, your application is unlikely to heavily depend on caching. In fact, you might only be using caching as a method to improve performance. In such a scenario, your application might run smoothly even when cache-related errors occur. So, you might not even be aware of failures in your caching system, making them difficult to spot. This is why implementing a system to properly handle cache-related errors is essential.

Let's see how to do so in both Java and Kotlin.

Handling Cache-Related Errors

To handle cache failures, Spring Boot provides the CacheErrorHandler interface. By implementing it, you can define your desired error-handling logic. Then, you only have to register your custom implementation as the default error handler. Let's take a look at how to accomplish both of these things.

Defining custom error-handling logic

The CacheErrorHandler interface provides the following four methods: handleCacheGetError, handleCachePutError, handleCacheEvictError, and handleCacheClearError. Each is intended to help you deal with errors occurring in methods annotated with @Cachable, @CachePut, or @CacheEvict, which are the most important Spring Boot caching-related annotations.

What you need to do is just implement the CacheErrorHandler interface, providing error-handling logic within the four aforementioned methods.

Java

public class CustomCacheErrorHandlerpublic implements CacheErrorHandler {
    @Override
    public void handleCacheGetError(
            RuntimeException e, 
            Cache cache, 
            Object key
    ) {
        // your custom error handling logic
    }

    @Override
    public void handleCachePutError(
            RuntimeException e, 
            Cache cache, 
            Object key, 
            Object value
    ) {
        // your custom error handling logic
    }

    @Override
    public void handleCacheEvictError(
            RuntimeException e, 
            Cache cache, 
            Object key
    ) {
        // your custom error handling logic
    }

    @Override
    public void handleCacheClearError(
            RuntimeException e, 
            Cache cache
    ) {
        // your custom error handling logic
    }
}

Kotlin

class CustomCacheErrorHandler : CacheErrorHandler {
    override fun handleCacheGetError(
        exception: RuntimeException,
        cache: Cache,
        key: Any
    ) {
        // your custom error handling logic
    }

    override fun handleCachePutError(
        exception: RuntimeException,
        cache: Cache,
        key: Any,
        value: Any?
    ) {
        // your custom error handling logic
    }

    override fun handleCacheEvictError(
        exception: RuntimeException,
        cache: Cache,
        key: Any
    ) {
        // your custom error handling logic
    }

    override fun handleCacheClearError(
        exception: RuntimeException,
        cache: Cache
    ) {
        // your custom error handling logic
    }
}

This way, you can log cache-related errors, no longer ignore them, or send them back to the clients in case of fatal exceptions.

Registering your custom CacheErrorHandler implementation

Now, you have to define a CustomachingConfiguration class inheriting from CachingConfigurerSupport. Override its errorHandler method and make sure to return an instance of your CustomCacheErrorHandler class defined above.

Java

@Configuration
public class CustomCachingConfiguration extends CachingConfigurerSupport {  
    @Override
    public CacheErrorHandler errorHandler() {
        return new CustomCacheErrorHandler();
    }

    // ...
}

Kotlin

@Configuration
class CustomCachingConfiguration : CachingConfigurerSupport() {
    override fun errorHandler(): CacheErrorHandler {
        return CustomCacheErrorHandler()
    }

    // ...
}

Et voilà! Your application is now protected from cache-related failures.

Conclusion

Dealing with caching is tricky, and you might not even be aware of errors occurring or be able to replicate them. This is exactly why you should adopt an approach aimed at gracefully handling cache-related errors. As we have just seen, adding error-handling logic to a caching system in your Spring Boot application is not complex, and it can allow you to avoid headaches in the future.

Thanks for reading! I hope that you found this article helpful.

The post "How To Handle Cache-Related Errors in Spring Boot" appeared first on Writech.