在异常时假装客户端重试

Question

java prettyprint-override">Retryer<ClientResponse> retryer = RetryerBuilder.<ClientResponse>newBuilder()
  .retryIfExceptionOfType(FeignException.class)
  .withStopStrategy(StopStrategies.stopAfterAttempt(retryCount))
  .withWaitStrategy(WaitStrategies.exponentialWait(maxWaitSeconds, TimeUnit.SECONDS))
  .build();
    
retryer.call(() -> { 
  return client.doStuffs(someInput); }
);

Feign client = Feign.builder()
    .decoder(jacksonDecoder)
    .encoder(jacksonEncoder)
    .logger(slf4jLogger)
    .client(okHttpClient)
    .retryer(new Retryer.Default(
                            SECONDS.toMillis(minWaitSeconds), 
                            SECONDS.toMillis(maxWaitSeconds), 
                            retryCount
            ))
    .requestInterceptor(new BasicAuthRequestInterceptor(clientConfig.getUser(), clientConfig.getPassword()))
    .target(target);
    
client.doStuffs(someInput);

<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-core</artifactId>
    <version>${feign.version}</version>
</dependency>

Answer 1

如果没有其他配置，则Feign将只在IOException上重试。如果希望基于状态代码重试，则需要创建一个ErrorDecoder，该RetryableException或其导数，以触发重试。

下面是一个简单的例子：

class MyErrorDecoder implements ErrorDecoder {
    public Exception decode(String methodKey, Response response) {
        if (response.status() == 503) {
            throw new RetryableException(
                response.status(), 
                "Service Unavailable", 
                response.request().httpMethod(), 
                null);
        } else {
            return new RuntimeException("error");
        }
    }
}

有关更多示例，请查看错误处理文档。