What is the circuit breaker pattern and how do I implement it?

What is the circuit breaker pattern and how do I implement it?

The circuit breaker pattern is a design pattern used to detect failures and prevent the system from making repeated requests that are likely to fail. It helps to improve the stability of an application.

Can you give me an example of how to implement it in code?

Sure! In Java, you can use a library like Resilience4j. Here's a simple example:

CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("myCircuitBreaker");

Supplier<String> decoratedSupplier = CircuitBreaker.decorateSupplier(circuitBreaker, () -> riskyOperation());

String result = Try.ofSupplier(decoratedSupplier)
                   .recover(throwable -> "Fallback response");

What are the key components of the circuit breaker pattern?

The key components are:

1. Closed State: Normal operation, requests are allowed.
2. Open State: Requests are blocked after a failure threshold is reached.
3. Half-Open State: Allows a limited number of requests to check if the service has recovered.

How do I know when to switch states?

You typically switch states based on failure rates and timeouts. For example, if the failure rate exceeds a certain threshold within a defined time window, you switch to the open state.