MOVED

This project is now hosted by resilience4j. https://github.com/resilience4j/resilience4j

ratpack-resilience4j

Ratpack support for resilience4j. https://github.com/resilience4j/resilience4j

Gradle

compile 'me.drmaas:ratpack-resilience4j:x.x.x'

Maven

<dependency>
    <groupId>me.drmaas</groupId>
    <artifactId>ratpack-resilience4j</artifactId>
    <version>x.x.x/version>
</dependency>

Examples

Circuit break promises

    CircuitBreakerConfig config = CircuitBreakerConfig.custom()
      .failureRateThreshold(50)
      .waitDurationInOpenState(Duration.ofMillis(1000))
      .ringBufferSizeInHalfOpenState(2)
      .ringBufferSizeInClosedState(2)
      .build()
    CircuitBreaker breaker = CircuitBreaker.of("test", config)
    
    CircuitBreakerTransformer<String> transformer = CircuitBreakerTransformer.of(breaker).recover { t -> "bar" }
    
    def r = ExecHarness.yieldSingle {
      Blocking.<String>get { 
        throw new Exception("test")
      }.transform(transformer)
    }
    r.value == "bar"
    breaker.state == CircuitBreaker.State.CLOSED
    
    r = ExecHarness.yieldSingle {
      Blocking.<String>get { 
        throw e 
      }.transform(transformer)
    }
    r.value == "bar"
    breaker.state == CircuitBreaker.State.OPEN

Retry promises

    RetryConfig config = RetryConfig.custom()
      .maxAttempts(3)
      .waitDuration(Duration.ofMillis(500))
      .build()
    Retry rate = Retry.of("test", config)
    RetryTransformer<String> transformer = RetryTransformer.of(rate).recover { t -> "bar" }
    AtomicInteger times = new AtomicInteger(0)

    when:
    def r = ExecHarness.yieldSingle {
      Blocking.<String>get { 
        times.getAndIncrement()
        throw new Exception("test")
      }.transform(transformer)
    }

    then:
    r.value == "bar"
    times.get() == 3

Circuit breaker annotations

Simply set up the circuit breaker registry and register your circuit breakers before binding the registry. The annotation will look up your circuit breaker by name.

The annotation is tested for Promise, Observable, Flowable, CompletionStage, and generic Object types.

ratpack {
  bindings {
    bindInstance(CircuitBreakerRegistry, someRegistry)
    bind(Something)
    module(ResilienceModule)
  } 
  handlers {
    get('promise') { Something something ->
      something.breakerPromise().then {
        render it
      }
    }
  }
}

class Something {

  @Breaker(name = "test", recovery = MyRecoveryFunction)
  Promise<String> breakerPromise() {
    Promise.async {
      it.error(new Exception("grrr"))
    }
  }
  
}

class MyRecoveryFunction implements RecoveryFunction<String> {
  @Override
  String apply(Throwable t) throws Exception {
    "recovered"
  }
}