springboot-cloud-7-eureka-source

pre start

    開始EnableEurekaClient註解

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
// 導入EnableDiscoveryClientImportSelector 配置
@Import({EnableDiscoveryClientImportSelector.class}) 
public @interface EnableDiscoveryClient {
    boolean autoRegister() default true;
}

    主要是加載配置文件到達開啓服務
    selectImports ： 如xml中import 其它xml文件
    selectImports： 加載META-INF/spring.factories 的類

//加載配置 如xml中配置 import（spring bean生命週期 ）
 public String[] selectImports(AnnotationMetadata metadata) {
        String[] imports = super.selectImports(metadata);
        AnnotationAttributes attributes = AnnotationAttributes.fromMap(metadata.getAnnotationAttributes(this.getAnnotationClass().getName(), true));
        boolean autoRegister = attributes.getBoolean("autoRegister");
        if(autoRegister) {
            List<String> importsList = new ArrayList(Arrays.asList(imports));
            importsList.add("org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationConfiguration");
            imports = (String[])importsList.toArray(new String[0]);
        }

        return imports;
    }
 //開啓條件 配置 spring.cloud.discovery.enabled = true
    protected boolean isEnabled() {
        return ((Boolean)(new RelaxedPropertyResolver(this.getEnvironment())).getProperty("spring.cloud.discovery.enabled", Boolean.class, Boolean.TRUE)).booleanValue();
    }

// String[] imports = super.selectImports(metadata);
//執行父類的加載 會執行META-INF/spring.factories 中的配置文件
            List<String> factories = new ArrayList(new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(this.annotationClass, this.beanClassLoader)));

    開啓默認配置
    spring.cloud.service-registry.auto-registration =true

@Configuration
//開啓配置  加載AutoServiceRegistrationProperties
@EnableConfigurationProperties({AutoServiceRegistrationProperties.class})
public class AutoServiceRegistrationConfiguration {
    public AutoServiceRegistrationConfiguration() {
    }
}

server start EurekaServerAutoConfiguration

    @Import(EurekaServerInitializerConfiguration.class) 導入配置
    其中繼承SmartLifecycle 加入spring生命週期

@Override
    public void start() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //TODO: is this class even needed now?
//初始化加載                 eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
                    log.info("Started Eureka Server");

                    publish(new EurekaRegistryAvailableEvent(getEurekaServerConfig()));
                    EurekaServerInitializerConfiguration.this.running = true;
                    publish(new EurekaServerStartedEvent(getEurekaServerConfig()));
                }
                catch (Exception ex) {
                    // Help!
                    log.error("Could not initialize Eureka servlet context", ex);
                }
            }
        }).start();
    }


protected void initEurekaServerContext() throws Exception {
        //省略xml解析
EurekaServerContextHolder.initialize(this.serverContext);

        log.info("Initialized server context");

        // Copy registry from neighboring eureka node
        //同步相鄰服務下的節點信息
        int registryCount = this.registry.syncUp();
        //註冊自己爲up狀態 開啓任務renew 與 ecic 任務
    this.registry.openForTraffic(this.applicationInfoManager, registryCount);

        // Register all monitoring statistics.
        EurekaMonitors.registerAllStats();
    }
// 定時renew 與 evic 任務
protected void postInit() {
        renewsLastMin.start();
        if (evictionTaskRef.get() != null) {
            evictionTaskRef.get().cancel();
        }
        evictionTaskRef.set(new EvictionTask());
        evictionTimer.schedule(evictionTaskRef.get(),
                serverConfig.getEvictionIntervalTimerInMs(),
                serverConfig.getEvictionIntervalTimerInMs());
    }

DefaultEurekaServerContext

@PostConstruct
    @Override
    public void initialize() throws Exception {
        logger.info("Initializing ...");
        peerEurekaNodes.start();
        registry.init(peerEurekaNodes);
        logger.info("Initialized");
    }

public void start() {
        taskExecutor = Executors.newSingleThreadScheduledExecutor(
                new ThreadFactory() {
                    @Override
                    public Thread newThread(Runnable r) {
                        Thread thread = new Thread(r, "Eureka-PeerNodesUpdater");
                        thread.setDaemon(true);
                        return thread;
                    }
                }
        );
        try {
        //resolvePeerUrls  serverUrl 地址
            updatePeerEurekaNodes(resolvePeerUrls());
            Runnable peersUpdateTask = new Runnable() {
                @Override
                public void run() {
                    try {
                        updatePeerEurekaNodes(resolvePeerUrls());
                    } catch (Throwable e) {
                        logger.error("Cannot update the replica Nodes", e);
                    }

                }
            };
            taskExecutor.scheduleWithFixedDelay(
                    peersUpdateTask,
                    serverConfig.getPeerEurekaNodesUpdateIntervalMs(),
                    serverConfig.getPeerEurekaNodesUpdateIntervalMs(),
                    TimeUnit.MILLISECONDS
            );
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
        for (PeerEurekaNode node : peerEurekaNodes) {
            logger.info("Replica node URL:  " + node.getServiceUrl());
        }
    }