Spring Cloud Eureka源码分析(二) : Eureka Server端源码分析

女爷i 2023-06-28 08:50 14阅读 0赞

### 文章目录 ###

*  前言
 *  1.自动配置类-EurekaServerAutoConfiguration
 *   *  EurekaControoler 解析
     *  EurekaServerInitializerConfiguration 解析
     *  EurekaServerBootstrap 解析
     *   *  contextInitialize() 解析
         *  initEurekaEnvironmen() 解析
         *  initEurekaServerContext() 解析
         *  syncUp() 解析

# 前言 #

我们按照如下流程去看eureka server源码  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70]  
自动配置 -> server启动 -> 初始化上下文 -> 创建服务注册表 -> 心跳监控

# 1.自动配置类-EurekaServerAutoConfiguration #

这个类里面，主要了三件事

*  1 加载对外提供eruka信息的的接口
 *  2 初始化集群注册表
 *  3 配置节点信息-双节点成集群
 *  4 上下文
 *  5 启动server
 *  6 配置拦截器

@Configuration
     @Import(EurekaServerInitializerConfiguration.class)
     @ConditionalOnBean(EurekaServerMarkerConfiguration.Marker.class)
     @EnableConfigurationProperties({  EurekaDashboardProperties.class,
     InstanceRegistryProperties.class })
     @PropertySource("classpath:/eureka/server.properties")
     public class EurekaServerAutoConfiguration extends WebMvcConfigurerAdapter { 
    
     
     // 加载EurekaController(下面会讲), 用来获取eurekaServer的信息
     @Bean
     @ConditionalOnProperty(prefix = "eureka.dashboard", name = "enabled", matchIfMissing = true)
     public EurekaController eurekaController() { 
     	return new EurekaController(this.applicationInfoManager);
     }
    
     //初始化集群注册表
     @Bean
     public PeerAwareInstanceRegistry peerAwareInstanceRegistry(
    	 ServerCodecs serverCodecs) { 
    	 this.eurekaClient.getApplications(); // force initialization
    	 return new InstanceRegistry(this.eurekaServerConfig, this.eurekaClientConfig,serverCodecs, this.eurekaClient,
    	 this.instanceRegistryProperties.getExpectedNumberOfRenewsPerMin(),
    	 this.instanceRegistryProperties.getDefaultOpenForTrafficCount());
     }
    
     // 配置服务节点信息，这里的作用主要是为了配置Eureka的peer节点，也就是说当有收到有节点注册上来
     //的时候，需要通知给那些服务节点， （互为一个集群）
     @Bean
     @ConditionalOnMissingBean
     public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry,
     ServerCodecs serverCodecs) { 
    	 return new PeerEurekaNodes(registry, this.eurekaServerConfig,
    	 this.eurekaClientConfig, serverCodecs, this.applicationInfoManager);
     }
     
     // EurekaServer的上下文
     @Bean
     public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) { 
    	 return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs,
    	 registry, peerEurekaNodes, this.applicationInfoManager);
     }
     // 这个类的作用是spring‐cloud和原生eureka的胶水代码，通过这个类来启动EurekaSever
     // 后面这个类会在EurekaServerInitializerConfiguration被调用，进行eureka启动
     @Bean
     public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry,EurekaServerContext serverContext) { 
    	 return new EurekaServerBootstrap(this.applicationInfoManager,
    	 this.eurekaClientConfig, this.eurekaServerConfig, registry,
    	 serverContext);
     }
     // 配置拦截器，通过他来实现eurekaServer对外的restFull接口
       @Bean
        public FilterRegistrationBean jerseyFilterRegistration(Application eurekaJerseyApp) { 
            FilterRegistrationBean bean = new FilterRegistrationBean();
            bean.setFilter(new ServletContainer(eurekaJerseyApp));
            bean.setOrder(2147483647);
            bean.setUrlPatterns(Collections.singletonList("/eureka/*"));
            return bean;
        }

## EurekaControoler 解析 ##

EurekaControoler.class 这个类很好理解，字面意思即功能，开放出一个rest接口

> 定义

@Controller
    @RequestMapping({ "${eureka.dashboard.path:/}"})
    public class EurekaController { 
        @Value("${eureka.dashboard.path:/}")
        private String dashboardPath = "";
        private ApplicationInfoManager applicationInfoManager;
    
        public EurekaController(ApplicationInfoManager applicationInfoManager) { 
            this.applicationInfoManager = applicationInfoManager;
        }
    }

> 方法  
> ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 1]

观察看 这个方法

public String status(HttpServletRequest request, Map<String, Object> model) { 
            this.populateBase(request, model);
            this.populateApps(model);
    
            StatusInfo statusInfo;
            try { 
                statusInfo = (new StatusResource()).getStatusInfo();
            } catch (Exception var5) { 
                statusInfo = Builder.newBuilder().isHealthy(false).build();
            }
    
            model.put("statusInfo", statusInfo);
            this.populateInstanceInfo(model, statusInfo);
            this.filterReplicas(model, statusInfo);
            return "eureka/status";
        }

我们点进去 `populateInstanceInfo()`

private void populateInstanceInfo(Map<String, Object> model, StatusInfo statusInfo) { 
            InstanceInfo instanceInfo = statusInfo.getInstanceInfo();
            Map<String, String> instanceMap = new HashMap();
            instanceMap.put("ipAddr", instanceInfo.getIPAddr());
            instanceMap.put("status", instanceInfo.getStatus().toString());
            if (instanceInfo.getDataCenterInfo().getName() == Name.Amazon) { 
                AmazonInfo info = (AmazonInfo)instanceInfo.getDataCenterInfo();
                instanceMap.put("availability-zone", info.get(MetaDataKey.availabilityZone));
                instanceMap.put("public-ipv4", info.get(MetaDataKey.publicIpv4));
                instanceMap.put("instance-id", info.get(MetaDataKey.instanceId));
                instanceMap.put("public-hostname", info.get(MetaDataKey.publicHostname));
                instanceMap.put("ami-id", info.get(MetaDataKey.amiId));
                instanceMap.put("instance-type", info.get(MetaDataKey.instanceType));
            }
    
            model.put("instanceInfo", instanceMap);
        }

在这个里面，可以看到`instanceMap`这个字段，里面看到了`instance-id`,`instance-type`就是存储的实例信息，也就是说，每次启动的时候，都会走这个方法，去把当前节点给注册进去(除了设置不注册自己)

## EurekaServerInitializerConfiguration 解析 ##

`EurekaServerAutoConfiguration` 这个类，他引入`(import)` 了这个`EurekaServerInitializerConfiguration`类  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 2]

我们点进去看看里面都有啥  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 3]  
怎么看就是这个`start()`有点特殊，我们点开方法看看

public void start() { 
    		// 这里启动了一个线程
            (new Thread(new Runnable() { 
                public void run() { 
                    try { 
                 
    				//初始化EurekaServer，同时启动Eureka Server
                    EurekaServerInitializerConfiguration.this.eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
    
    				// 日志 不管
                    EurekaServerInitializerConfiguration.log.info("Started Eureka Server");
                       
                    // 发布EurekaServer的注册事件
                    EurekaServerInitializerConfiguration.this.publish(new EurekaRegistryAvailableEvent(EurekaServerInitializerConfiguration.this.getEurekaServerConfig()));
                        
                    // 设置启动的状态为true
                    EurekaServerInitializerConfiguration.this.running = true;
    
    				// 发送Eureka Start 事件 ， 其他还有各种事件，我们可以监听这种时间，然后做一些特定的业务需求
                    EurekaServerInitializerConfiguration.this.publish(new EurekaServerStartedEvent(EurekaServerInitializerConfiguration.this.getEurekaServerConfig()));
                    } catch (Exception var2) { 
                        EurekaServerInitializerConfiguration.log.error("Could not initialize Eureka servlet context", var2);
                    }
    
                }
            })).start();
        }

到了这一步，各项配置和参数准备好了，就差启动了！下面看这个类

## EurekaServerBootstrap 解析 ##

依旧在 `EurekaServerAutoConfiguration` 中，存在这么一个方法

@Bean
    public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry, EurekaServerContext serverContext) { 
       return new EurekaServerBootstrap(this.applicationInfoManager, this.eurekaClientConfig, this.eurekaServerConfig, registry, serverContext);
    }

废话少说，跟进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 4]

我们先看下这个方法 `contextInitialize`

### contextInitialize() 解析 ###

里面并没有什么东西，就是调自身的两个方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 5]  
先看第一个 `initEurekaEnvironmen()`

### initEurekaEnvironmen() 解析 ###

这个方法里面，设置了服务实例的的相关属性，字面意思是数据中心和环境，默认是`test`环境  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQxMzE2MTc_size_16_color_FFFFFF_t_70 6]

### initEurekaServerContext() 解析 ###

这个方法很关键，是在这个方法里面，去初始化eureka server的上下文的

protected void initEurekaServerContext() throws Exception { 
            JsonXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), 10000);
            XmlXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(), 10000);
            if (this.isAws(this.applicationInfoManager.getInfo())) { 
                this.awsBinder = new AwsBinderDelegate(this.eurekaServerConfig, this.eurekaClientConfig, this.registry, this.applicationInfoManager);
                this.awsBinder.start();
            }
    
    
    		// 初始化eureka server上下文
            EurekaServerContextHolder.initialize(this.serverContext);
            log.info("Initialized server context");
            // 从相邻的eureka节点复制注册表
            int registryCount = this.registry.syncUp();
            // 默认每30秒发送心跳，1分钟就是2次
    		// 修改eureka状态为up
    		// 同时，这里面会开启一个定时任务，用于清理60秒没有心跳的客户端。自动下线
            this.registry.openForTraffic(this.applicationInfoManager, registryCount);
            EurekaMonitors.registerAllStats();
        }

这个方法里面，有一个`syncUp()`方法，这个方法有什么用呢？

### syncUp() 解析 ###

这个方法，就是开始把其他服务往自己身上`循环`注册  
字面意思是 `同步启动` ，看下到底是有什么作用

public int syncUp() { 
            int count = 0;
    		
            for(int i = 0; i < this.serverConfig.getRegistrySyncRetries() && count == 0; ++i) { 
                if (i > 0) { 
                    try { 
                        Thread.sleep(this.serverConfig.getRegistrySyncRetryWaitMs());
                    } catch (InterruptedException var10) { 
                        logger.warn("Interrupted during registry transfer..");
                        break;
                    }
                }
    
                Applications apps = this.eurekaClient.getApplications();
                Iterator var4 = apps.getRegisteredApplications().iterator();
    
                while(var4.hasNext()) { 
                    Application app = (Application)var4.next();
                    // 获取服务实例列表 -> 这一步就是client往server上注册啦
                    Iterator var6 = app.getInstances().iterator();
    
                    while(var6.hasNext()) { 
                        InstanceInfo instance = (InstanceInfo)var6.next();
    
                        try { 
                            if (this.isRegisterable(instance)) { 
                            // 将其他节点的实例注册到本节点
                                this.register(instance, instance.getLeaseInfo().getDurationInSecs(), true);
                                ++count;
                            }
                        } catch (Throwable var9) { 
                            logger.error("During DS init copy", var9);
                        }
                    }
                }
            }
    
            return count;
        }

server端快解析完了，可是我不想写了，明天再写！~ 累…

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