Spring Cloud Resilience4j Circuitbreaker不调用回退

问题描述

我正在尝试使用spring cloud resilience4j库实现断路器，以便在供应商api返回500错误或超时时使用AsyncHttpClient调用该api。问题似乎是当API返回500个错误时，断路器永远不会断开，并且fallback方法也永远不会执行。

可能是由于我覆盖了onFailure（这样做是为了捕获指标）

工厂声明如下：

@Autowired
private CircuitBreakerFactory circuitBreakerFactory;

出厂配置定义如下：

@Bean
public Customizer<Resilience4JCircuitBreakerFactory> specificCustomConfiguration1() {

    TimeLimiterConfig timeLimiterConfig = TimeLimiterConfig.custom()
            .timeoutDuration(Duration.ofSeconds(2))
            .build();
    CircuitBreakerConfig circuitBreakerConfig = CircuitBreakerConfig.custom()
            .failureRateThreshold(50)
            .waitDurationInOpenState(Duration.ofMillis(1000))
            .slidingWindowSize(2)
            .build();

    return factory -> factory.configure(builder -> builder.circuitBreakerConfig(circuitBreakerConfig)
            .timeLimiterConfig(timeLimiterConfig).build(),"circuitBreaker");
}

使用以下方法调用该API，该方法还具有断路器和.run方法：

private void getRecommendationsAsync(final GatewayRecommendationsRequest request,final String variantName,final ThinkCallbackHandler callbackHandler)
        throws URISyntaxException,JsonProcessingException {

    CircuitBreaker circuitBreaker = circuitBreakerFactory.create("circuitBreaker");



    final AsyncHttpClient.BoundRequestBuilder builder = requestBuilder
            .prepareRequest(asyncHttpClient,request,variantName);


    circuitBreaker.run(() -> builder.execute(new AsyncCompletionHandler<Response>() {
        @Override
        public Response onCompleted(final Response response)
                throws Exception {
            processResponseStatus(response,variantName);

            GatewayRecommendations gatewayRecommendations = ((ThinkResponseMapper) responseMapper).map(request,response,useCaseId,variantName);
            validator.validateResponse("/v1/recommendations",Request.Method.GET,gatewayRecommendations);
            callbackHandler.onSuccess(gatewayRecommendations);
            return response;
        }

        @Override
        public void onThrowable(final Throwable t) {
            callbackHandler.onFailure(t,recommendationsUri + " " + parameters.toString(),variantName);
        }


    }),throwable -> fallback());

}

最后是我要调用的后备方法：

public String fallback() {
    LOGGER.warn("The fallback method is being used");
    System.out.println("Fallback Method is being executed");
    return "The circuit breaker is open";
}

解决方法

您是否使用AsyncHttpClient？

您可以尝试我们的Resilience4j Spring Boot 2 Starter。它提供注释支持，外部配置，指标，重试和更多功能。

如果您可以返回CompletableFuture，则它可能如下所示：

@CircuitBreaker(name = "circuitBreaker",fallbackMethod="fallback")
public CompletableFuture<GatewayRecommendations> getRecommendationsAsync(final GatewayRecommendationsRequest request,final String variantName,final ThinkCallbackHandler callbackHandler)
        throws URISyntaxException,JsonProcessingException {

    final AsyncHttpClient.BoundRequestBuilder builder = requestBuilder
            .prepareRequest(asyncHttpClient,request,variantName);

    return builder.execute().toCompletableFuture()            
            .exceptionally(t -> { /* Something wrong happened... */  } )
            .thenApply(response -> { /*  Validate response and extract GatewayRecommendations  */  
   });


}

public CompletableFuture<GatewayRecommendations> fallback(RequestNotPermitted ex) {
    // The circuit breaker is open
    // Return a static list of recommendations
    return CompletableFuture.completedFuture(..)
}