关于spring-cloud:SpringCloud升级之路20200x版39-改造-resilience4j-粘合-WebClient

本系列代码地址：https://github.com/JoJoTec/sp…

要想实现咱们上一节中提到的：

须要在重试以及断路中加一些日志，便于日后的优化
须要定义重试的 Exception，并且与断路器相结合，将非 2xx 的响应码也封装成特定的异样
须要在断路器相干的 Operator 中减少相似于 FeignClient 中的负载平衡的数据更新，使得负载平衡更加智能

咱们须要将 resilience4j 自身提供的粘合库做一些革新，其实次要就是对 resilience4j 实现的 project reactor 的 Operator 进行革新。

首先，WebClient 的返回对象只可能是 ClientResponse 类型，所以咱们这里革新进去的 Operator 不用带上形参，只须要针对 ClientResponse 即可，即：

public class ClientResponseCircuitBreakerOperator implements UnaryOperator<Publisher<ClientResponse>> {...}

在原有的断路器逻辑中，咱们须要退出针对 GET 办法以及之前定义的能够重试的门路匹配配置能够重试的逻辑，这须要咱们拿到原有申请的 URL 信息。然而 ClientResponse 中并没有裸露这些信息的接口，其默认实现 DefaultClientResponse（咱们只有没有本人给 WebClient 退出非凡的革新逻辑，实现都是 DefaultClientResponse）中的 request() 办法能够获取申请 HttpRequest，其中蕴含 url 信息。然而这个类还有办法都是 package-private 的，咱们须要反射进去：

ClientResponseCircuitBreakerSubscriber

private static final Class<?> aClass;
private static final Method request;

static {
    try {aClass = Class.forName("org.springframework.web.reactive.function.client.DefaultClientResponse");
        request = ReflectionUtils.findMethod(aClass, "request");
        request.setAccessible(true);
    } catch (Exception e) {throw new RuntimeException(e);
    }
}

之后，在获取到 ClientResponse 之后记录断路器的逻辑中，须要退出下面提到的对于重试的革新，以及负载均衡器的记录：

ClientResponseCircuitBreakerSubscriber

protected void hookOnNext(ClientResponse clientResponse) {if (!isDisposed()) {if (singleProducer && successSignaled.compareAndSet(false, true)) {int rawStatusCode = clientResponse.rawStatusCode();
            HttpStatus httpStatus = HttpStatus.resolve(rawStatusCode);
            try {HttpRequest httpRequest = (HttpRequest) request.invoke(clientResponse);
                // 判断办法是否为 GET，以及是否在可重试门路配置中，从而得出是否能够重试
                if (httpRequest.getMethod() != HttpMethod.GET && !webClientProperties.retryablePathsMatch(httpRequest.getURI().getPath())) {
                    // 如果不能重试，则间接返回后果
                    circuitBreaker.onResult(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit(), clientResponse);
                } else {if (httpStatus != null && httpStatus.is2xxSuccessful()) {
                        // 如果胜利，则间接返回后果
                        circuitBreaker.onResult(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit(), clientResponse);
                    } else {
                        /**
                         * 如果异样，参考 DefaultClientResponse 的代码进行异样封装
                         * @see org.springframework.web.reactive.function.client.DefaultClientResponse#createException
                         */
                        Exception exception;
                        if (httpStatus != null) {exception = WebClientResponseException.create(rawStatusCode, httpStatus.getReasonPhrase(), clientResponse.headers().asHttpHeaders(), EMPTY, null, null);
                        } else {exception = new UnknownHttpStatusCodeException(rawStatusCode, clientResponse.headers().asHttpHeaders(), EMPTY, null, null);
                        }
                        circuitBreaker.onError(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit(), exception);
                        downstreamSubscriber.onError(exception);
                        return;
                    }
                }
            } catch (Exception e) {log.fatal("judge request method in circuit breaker error! the resilience4j feature would not be enabled: {}", e.getMessage(), e);
                circuitBreaker.onResult(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit(), clientResponse);
            }
        }
        eventWasEmitted.set(true);
        downstreamSubscriber.onNext(clientResponse);
    }
}

同样的，在原有的实现，勾销还有失败的记录逻辑中，也加上记录负载平衡数据：

ClientResponseCircuitBreakerSubscriber

@Override
protected void hookOnComplete() {if (successSignaled.compareAndSet(false, true)) {serviceInstanceMetrics.recordServiceInstanceCalled(serviceInstance, true);
        circuitBreaker.onSuccess(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit());
    }

    downstreamSubscriber.onComplete();}

@Override
public void hookOnCancel() {if (!successSignaled.get()) {serviceInstanceMetrics.recordServiceInstanceCalled(serviceInstance, true);
        if (eventWasEmitted.get()) {circuitBreaker.onSuccess(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit());
        } else {circuitBreaker.releasePermission();
        }
    }
}

@Override
protected void hookOnError(Throwable e) {serviceInstanceMetrics.recordServiceInstanceCalled(serviceInstance, false);
    circuitBreaker.onError(circuitBreaker.getCurrentTimestamp() - start, circuitBreaker.getTimestampUnit(), e);
    downstreamSubscriber.onError(e);
}

因为后面的断路器中，咱们针对能够重试的非 2XX 响应封装成为 WebClientResponseException。所以在重试器中，咱们须要加上针对这个异样的重试。

同时，须要将 重试器 放在 负载均衡器 之前，因为每次重试，都要从负载均衡器中获取一个新的实例。同时，断路器 须要放在 负载均衡器 之后，因为只有在这个之后，能力获取到本次调用的实例，咱们的的断路器是针对实例办法级别的：

WebClientDefaultConfiguration.java

@Bean
public WebClient getWebClient(
        ReactorLoadBalancerExchangeFilterFunction lbFunction,
        WebClientConfigurationProperties webClientConfigurationProperties,
        Environment environment,
        RetryRegistry retryRegistry,
        CircuitBreakerRegistry circuitBreakerRegistry,
        ServiceInstanceMetrics serviceInstanceMetrics
) {String name = environment.getProperty(WebClientNamedContextFactory.PROPERTY_NAME);
    Map<String, WebClientConfigurationProperties.WebClientProperties> configs = webClientConfigurationProperties.getConfigs();
    if (configs == null || configs.size() == 0) {throw new BeanCreationException("Failed to create webClient, please provide configurations under namespace: webclient.configs");
    }
    WebClientConfigurationProperties.WebClientProperties webClientProperties = configs.get(name);
    if (webClientProperties == null) {throw new BeanCreationException("Failed to create webClient, please provide configurations under namespace: webclient.configs." + name);
    }
    String serviceName = webClientProperties.getServiceName();
    // 如果没填写微服务名称，就应用配置 key 作为微服务名称
    if (StringUtils.isBlank(serviceName)) {serviceName = name;}
    String baseUrl = webClientProperties.getBaseUrl();
    // 如果没填写 baseUrl，就应用微服务名称填充
    if (StringUtils.isBlank(baseUrl)) {baseUrl = "http://" + serviceName;}

    Retry retry = null;
    try {retry = retryRegistry.retry(serviceName, serviceName);
    } catch (ConfigurationNotFoundException e) {retry = retryRegistry.retry(serviceName);
    }
    // 笼罩其中的异样判断
    retry = Retry.of(serviceName, RetryConfig.from(retry.getRetryConfig()).retryOnException(throwable -> {
        //WebClientResponseException 会重试，因为在这里能 catch 的 WebClientResponseException 只对能够重试的申请封装了 WebClientResponseException
        // 参考 ClientResponseCircuitBreakerSubscriber 的代码
        if (throwable instanceof WebClientResponseException) {log.info("should retry on {}", throwable.toString());
            return true;
        }
        // 断路器异样重试，因为申请没有收回去
        if (throwable instanceof CallNotPermittedException) {log.info("should retry on {}", throwable.toString());
            return true;
        }
        if (throwable instanceof WebClientRequestException) {WebClientRequestException webClientRequestException = (WebClientRequestException) throwable;
            HttpMethod method = webClientRequestException.getMethod();
            URI uri = webClientRequestException.getUri();
            // 判断是否为响应超时，响应超时代表申请曾经收回去了，对于非 GET 并且没有标注能够重试的申请则不能重试
            boolean isResponseTimeout = false;
            Throwable cause = throwable.getCause();
            //netty 的读取超时个别是 ReadTimeoutException
            if (cause instanceof ReadTimeoutException) {log.info("Cause is a ReadTimeoutException which indicates it is a response time out");
                isResponseTimeout = true;
            } else {
                // 对于其余一些框架，应用了 java 底层 nio 的个别是 SocketTimeoutException，message 为 read time out
                // 还有一些其余异样，然而 message 都会有 read time out 字段，所以通过 message 判断
                String message = throwable.getMessage();
                if (StringUtils.isNotBlank(message) && StringUtils.containsIgnoreCase(message.replace("",""), "readtimeout")) {log.info("Throwable message contains readtimeout which indicates it is a response time out");
                    isResponseTimeout = true;
                }
            }
            // 如果申请是 GET 或者标注了重试，则直接判断能够重试
            if (method == HttpMethod.GET || webClientProperties.retryablePathsMatch(uri.getPath())) {log.info("should retry on {}-{}, {}", method, uri, throwable.toString());
                return true;
            } else {
                // 否则，只针对申请还没有收回去的异样进行重试
                if (isResponseTimeout) {log.info("should not retry on {}-{}, {}", method, uri, throwable.toString());
                } else {log.info("should retry on {}-{}, {}", method, uri, throwable.toString());
                    return true;
                }
            }
        }
        return false;
    }).build());


    HttpClient httpClient = HttpClient
            .create()
            .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, (int) webClientProperties.getConnectTimeout().toMillis())
            .doOnConnected(connection ->
                    connection
                            .addHandlerLast(new ReadTimeoutHandler((int) webClientProperties.getResponseTimeout().toSeconds()))
                            .addHandlerLast(new WriteTimeoutHandler((int) webClientProperties.getResponseTimeout().toSeconds()))
            );

    Retry finalRetry = retry;
    String finalServiceName = serviceName;
    return WebClient.builder()
            .exchangeStrategies(ExchangeStrategies.builder()
            .codecs(configurer -> configurer
                    .defaultCodecs()
                    // 最大 body 占用 16m 内存
                    .maxInMemorySize(16 * 1024 * 1024))
            .build())
            .clientConnector(new ReactorClientHttpConnector(httpClient))
            //Retry 在负载平衡前
            .filter((clientRequest, exchangeFunction) -> {
                return exchangeFunction
                        .exchange(clientRequest)
                        .transform(ClientResponseRetryOperator.of(finalRetry));
            })
            // 负载均衡器，改写 url
            .filter(lbFunction)
            // 实例级别的断路器须要在负载平衡获取真正地址之后
            .filter((clientRequest, exchangeFunction) -> {ServiceInstance serviceInstance = getServiceInstance(clientRequest);
                serviceInstanceMetrics.recordServiceInstanceCall(serviceInstance);
                CircuitBreaker circuitBreaker;
                // 这时候的 url 是通过负载均衡器的，是实例的 url
                // 须要留神的一点是，应用异步 client 的时候，最好不要带门路参数，否则这里的断路器成果不好
                // 断路器是每个实例每个门路一个断路器
                String instancId = clientRequest.url().getHost() + ":" + clientRequest.url().getPort() + clientRequest.url().getPath();
                try {
                    // 应用实例 id 新建或者获取现有的 CircuitBreaker, 应用 serviceName 获取配置
                    circuitBreaker = circuitBreakerRegistry.circuitBreaker(instancId, finalServiceName);
                } catch (ConfigurationNotFoundException e) {circuitBreaker = circuitBreakerRegistry.circuitBreaker(instancId);
                }
                log.info("webclient circuit breaker [{}-{}] status: {}, data: {}", finalServiceName, instancId, circuitBreaker.getState(), JSON.toJSONString(circuitBreaker.getMetrics()));
                return exchangeFunction.exchange(clientRequest).transform(ClientResponseCircuitBreakerOperator.of(circuitBreaker, serviceInstance, serviceInstanceMetrics, webClientProperties));
            }).baseUrl(baseUrl)
            .build();}

private ServiceInstance getServiceInstance(ClientRequest clientRequest) {URI url = clientRequest.url();
    DefaultServiceInstance defaultServiceInstance = new DefaultServiceInstance();
    defaultServiceInstance.setHost(url.getHost());
    defaultServiceInstance.setPort(url.getPort());
    return defaultServiceInstance;
}

这样，咱们就实现了咱们封装的基于配置的 WebClient

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关于spring-cloud:SpringCloud升级之路20200x版39-改造-resilience4j-粘合-WebClient

对于断路器的革新

粘合 WebClient 与 resilience4j 的同时笼罩重试逻辑

Just My Socks（注册教程内含优惠码）

关于spring-cloud:SpringCloud升级之路20200x版39-改造-resilience4j-粘合-WebClient

对于断路器的革新

粘合 WebClient 与 resilience4j 的同时笼罩重试逻辑

Just My Socks（注册教程 内含优惠码）

Just My Socks（注册教程内含优惠码）