Ribbon 原理初探

決心是成功的開始

Ribbon 使用方法

Ribbon 的使用方法是在 RestTemplate 的方法上面加上一個 **@LoadBalanced **注解,之後這個方法進行請求的時候就可以進行負載均衡請求了

@Configuration
public class RestConfig {
    @LoadBalanced
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

負載均衡原理圖解

RestTemplate 方法使用

如果不用 Ribbon 的話，在進行 http 請求的時候，直接 new 一個 RestTemplate 對象，通過相應的方法比如 getForEntity() 進行調用就可以了，這種情況直接請求就可以了，不會進行負載均衡的

@Override
public <T> ResponseEntity<T> getForEntity(String url, Class<T> responseType,
                                          Object... uriVariables)
        throws RestClientException {
    RequestCallback requestCallback = acceptHeaderRequestCallback(responseType);
    ResponseExtractor<ResponseEntity<T>> responseExtractor =
        responseEntityExtractor(responseType);
    // 執行請求
    return nonNull(execute(url, HttpMethod.GET, requestCallback,
                           responseExtractor, uriVariables));
}

@LoadBalanced 注解源碼

/**
 * Annotation to mark a RestTemplate bean to be configured to use a LoadBalancerClient.
 */
@Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Qualifier
public @interface LoadBalanced {
}

public interface LoadBalancerClient extends ServiceInstanceChooser {
    // 執行負載均衡器指定的服務請求
    <T> T execute(String serviceId, LoadBalancerRequest<T> request) throws IOException;
    // 執行負載均衡器指定的服務請求
    <T> T execute(String serviceId, ServiceInstance serviceInstance,
            LoadBalancerRequest<T> request) throws IOException;
    // 建立一個具有真實主機和端口的适當URI，供系統使用。
    // 一些系統使用帶有邏輯服務名稱的URI作為主機，
    // 例如 http://myservice/path/to/service
    // 這将用ServiceInstan中的主機：端口替換服務名稱
    URI reconstructURI(ServiceInstance instance, URI original);
}
/**
 * 通過負載均衡器選擇一個服務執行個體
 */
public interface ServiceInstanceChooser {
    ServiceInstance choose(String serviceId);
}

Ribbon用戶端配置類RibbonClientConfiguration

public class RibbonClientConfiguration {
// 用戶端連結逾時
public static final int DEFAULT_CONNECT_TIMEOUT = 1000;

// 用戶端讀取逾時
public static final int DEFAULT_READ_TIMEOUT = 1000;

@RibbonClientName
private String name = "client";

@Autowired
private PropertiesFactory propertiesFactory;
    ......
}

1. RibbonClientConfig 用戶端配置類

// Ribbon 用戶端配置類
@Bean
@ConditionalOnMissingBean
public IClientConfig ribbonClientConfig() {
    DefaultClientConfigImpl config = new DefaultClientConfigImpl();
    config.loadProperties(this.name);
    config.set(CommonClientConfigKey.ConnectTimeout, DEFAULT_CONNECT_TIMEOUT);
    config.set(CommonClientConfigKey.ReadTimeout, DEFAULT_READ_TIMEOUT);
    config.set(CommonClientConfigKey.GZipPayload, DEFAULT_GZIP_PAYLOAD);
    return config;
}

2. RibbonRule 規則

// Ribbon 規則類
@Bean
@ConditionalOnMissingBean
public IRule ribbonRule(IClientConfig config) {
    if (this.propertiesFactory.isSet(IRule.class, name)) {
        return this.propertiesFactory.get(IRule.class, config, name);
    }
    ZoneAvoidanceRule rule = new ZoneAvoidanceRule();
    rule.initWithNiwsConfig(config);
    return rule;
}

3. RibbonPing Ping方式

// Ribbon Ping類
@Bean
@ConditionalOnMissingBean
public IPing ribbonPing(IClientConfig config) {
    if (this.propertiesFactory.isSet(IPing.class, name)) {
        return this.propertiesFactory.get(IPing.class, config, name);
    }
    return new DummyPing();
}

4. Ribbon ribbonServerList 服務清單

// Ribbon 服務清單
@Bean
@ConditionalOnMissingBean
@SuppressWarnings("unchecked")
public ServerList<Server> ribbonServerList(IClientConfig config) {
    if (this.propertiesFactory.isSet(ServerList.class, name)) {
        return this.propertiesFactory.get(ServerList.class, config, name);
    }
    ConfigurationBasedServerList serverList = new ConfigurationBasedServerList();
    serverList.initWithNiwsConfig(config);
    return serverList;
}

5. RibbonServerListUpdater Ribbon 服務清單更新器

// Ribbon 服務清單更新器，預設選擇的是 PollingServerListUpdater 定時拉取
@Bean
@ConditionalOnMissingBean
public ServerListUpdater ribbonServerListUpdater(IClientConfig config) {
    return new PollingServerListUpdater(config);
}

6. RibbonLoadBalancer 服務的負載均衡器

// Ribbon 服務的負載均衡器
@Bean
@ConditionalOnMissingBean
public ILoadBalancer ribbonLoadBalancer(IClientConfig config,
        ServerList<Server> serverList, ServerListFilter<Server> serverListFilter,
        IRule rule, IPing ping, ServerListUpdater serverListUpdater) {
    if (this.propertiesFactory.isSet(ILoadBalancer.class, name)) {
        return this.propertiesFactory.get(ILoadBalancer.class, config, name);
    }
    return new ZoneAwareLoadBalancer<>(config, rule, ping, serverList,
            serverListFilter, serverListUpdater);
}

7. RibbonServerListFilter 服務清單篩選器

// 服務清單篩選器
@Bean
@ConditionalOnMissingBean
@SuppressWarnings("unchecked")
public ServerListFilter<Server> ribbonServerListFilter(IClientConfig config) {
    if (this.propertiesFactory.isSet(ServerListFilter.class, name)) {
        return this.propertiesFactory.get(ServerListFilter.class, config, name);
    }
    ZonePreferenceServerListFilter filter = new ZonePreferenceServerListFilter();
    filter.initWithNiwsConfig(config);
    return filter;
}

負載均衡器初始化核心配置類

Configuration
@ConditionalOnClass(RestTemplate.class)
@ConditionalOnBean(LoadBalancerClient.class)
@EnableConfigurationProperties(LoadBalancerRetryProperties.class)
public class LoadBalancerAutoConfiguration {

@LoadBalanced
@Autowired(required = false)
private List<RestTemplate> restTemplates = Collections.emptyList();

@Autowired(required = false)
private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();
// 負載均衡 RestTemplate 初始化配置
@Bean
public SmartInitializingSingleton loadBalancedRestTemplateInitializerDeprecated(
        final ObjectProvider<List<RestTemplateCustomizer>> restTemplateCustomizers) {
    return () -> restTemplateCustomizers.ifAvailable(customizers -> {
        for (RestTemplate restTemplate :
             LoadBalancerAutoConfiguration.this.restTemplates) {
            for (RestTemplateCustomizer customizer : customizers) {
                customizer.customize(restTemplate);
            }
        }
    });
}

@Bean
@ConditionalOnMissingBean
public LoadBalancerRequestFactory loadBalancerRequestFactory(
        LoadBalancerClient loadBalancerClient) {
    return new LoadBalancerRequestFactory(loadBalancerClient, this.transformers);
}
// 負載均衡攔截器配置
@Configuration
@ConditionalOnMissingClass("org.springframework.retry.support.RetryTemplate")
static class LoadBalancerInterceptorConfig {
    @Bean
    public LoadBalancerInterceptor ribbonInterceptor(
            LoadBalancerClient loadBalancerClient,
            LoadBalancerRequestFactory requestFactory) {
        return new LoadBalancerInterceptor(loadBalancerClient, requestFactory);
    }

    @Bean
    @ConditionalOnMissingBean
    public RestTemplateCustomizer restTemplateCustomizer(
            final LoadBalancerInterceptor loadBalancerInterceptor) {
        return restTemplate -> {
            List<ClientHttpRequestInterceptor> list = new ArrayList<>(
                    restTemplate.getInterceptors());
            list.add(loadBalancerInterceptor);
            restTemplate.setInterceptors(list);
        };
    }
                        ......
}

負載均衡攔截器 LoadBalancerInterceptor

@Override
public ClientHttpResponse intercept(final HttpRequest request, final byte[] body,
        final ClientHttpRequestExecution execution) throws IOException {
    // 解析服務位址
    final URI originalUri = request.getURI();
    // 請求服務名稱
    String serviceName = originalUri.getHost();
    // 執行的請求流程
    return this.loadBalancer.execute(serviceName,
            this.requestFactory.createRequest(request, body, execution));
}

負載均衡器執行請求 loadBalancer.execute

public <T> T execute(String serviceId, LoadBalancerRequest<T> request, Object hint)
        throws IOException {
    // 擷取負載均衡器
    ILoadBalancer loadBalancer = getLoadBalancer(serviceId);
    // 通過負載均衡器選擇可利用的服務
    Server server = getServer(loadBalancer, hint);
    if (server == null) {
        throw new IllegalStateException("No instances available for " + serviceId);
    }
    // 建立 Ribbon 服務
    RibbonServer ribbonServer = new RibbonServer(serviceId, server,
            isSecure(server, serviceId),
            serverIntrospector(serviceId).getMetadata(server));
    // 真正的執行請求
    return execute(serviceId, ribbonServer, request);
}

真正的執行請求

@Override
public <T> T execute(String serviceId, ServiceInstance serviceInstance,
        LoadBalancerRequest<T> request) throws IOException {
    Server server = null;
    if (serviceInstance instanceof RibbonServer) {
        server = ((RibbonServer) serviceInstance).getServer();
    }
    // 如果服務為空的情況下那麼就抛出異常沒有執行個體可以使用
    if (server == null) {
        throw new IllegalStateException("No instances available for " + serviceId);
    }

    RibbonLoadBalancerContext context = this.clientFactory
            .getLoadBalancerContext(serviceId);
    RibbonStatsRecorder statsRecorder = new RibbonStatsRecorder(context, server);

    try {
        // 真正的請求方法
        T returnVal = request.apply(serviceInstance);
        statsRecorder.recordStats(returnVal);
        return returnVal;
    }
    return null;
}

ServiceRequestWrapper 封裝請求進行服務請求

@Override
public ListenableFuture<ClientHttpResponse> intercept(final HttpRequest request,
        final byte[] body, final AsyncClientHttpRequestExecution execution)
        throws IOException {
    // 擷取請求的路徑URI
    final URI originalUri = request.getURI();
    // 擷取服務的位址
    String serviceName = originalUri.getHost();
    return this.loadBalancer.execute(serviceName,
            new LoadBalancerRequest<ListenableFuture<ClientHttpResponse>>() {
                // 執行的方法
                @Override
                public ListenableFuture<ClientHttpResponse> apply(
                        final ServiceInstance instance) throws Exception {
                    // 封裝請求
                    HttpRequest serviceRequest = new ServiceRequestWrapper(request,
                            instance, AsyncLoadBalancerInterceptor.this.loadBalancer);
                    // 進行服務調用執行通路
                    return execution.executeAsync(serviceRequest, body);
                }

            });
}

Ribbon 原理初探

Ribbon 原理初探

Ribbon 使用方法

負載均衡原理圖解

RestTemplate 方法使用

@LoadBalanced 注解源碼

Ribbon用戶端配置類RibbonClientConfiguration

1. RibbonClientConfig 用戶端配置類

2. RibbonRule 規則

3. RibbonPing Ping方式

4. Ribbon ribbonServerList 服務清單

5. RibbonServerListUpdater Ribbon 服務清單更新器

6. RibbonLoadBalancer 服務的負載均衡器

7. RibbonServerListFilter 服務清單篩選器

負載均衡器初始化核心配置類

負載均衡攔截器 LoadBalancerInterceptor

負載均衡器執行請求 loadBalancer.execute

真正的執行請求

ServiceRequestWrapper 封裝請求進行服務請求

小結

繼續閱讀

ZOJ 1041 Transmitters

CSU 1562 Fun House

CodeChef PALPROB Palindromeness

UVA 10344- 23 out of 5

ZOJ 1104 Leaps Tall Buildings

HDU 2821 Pusher

UVA 1401 Remember the Word

ZOJ 2748 Free Kick

CSU 1567 Reverse Rot

JAVA 系列——>開發工具IntelliJ IDEA的安裝以及配置、快捷鍵IDEA 簡介

UVA 519 Puzzle (II)

磁盤結構及在Linux中的命名

第三章 Joomla!擴充開發--後端開發（續2）

nginx location中斜線的位置的重要性

AOP程式設計_Android優雅權限架構(1)概念基礎，2021金三銀四前言正文大綱正文

express 搭建背景建構工程目錄結構