spring-cloud源码解析-zuul路由的部分源码解析

原创
2018/02/12 15:44
阅读数 988

版本:
spring-boot:1.5.3.RELEASE
spring cloud:Dalston.RELEASE(1.3.0.RELEASE)

路由定位器(RouteLocator)


主要作用:获取路由配置和匹配请求地址的路由地址

  • 配置所在jar包:spring-cloud-netflix-core-1.3.0.RELEASE.jar
  • 顶层接口:RouteLocator
  • 可刷新的路由:RefreshableRouteLocator extends RouteLocator
  • 路由处理器:CompositeRouteLocator implements RefreshableRouteLocator,所有的路由定位器都交由给它处理
  • 默认加载的路由定位器:SimpleRouteLocator implements RouteLocator, Ordered,实现Ordered接口达到排序的效果

配置


  • 配置类:ZuulProxyConfiguration extends ZuulConfiguration,ZuulConfiguration中包含默认的一些公共的filter,ZuulProxyConfiguration包含spring cloud的需要的一些filter,如:host解析、ribbon负载均衡等
  • zuul初始化配置不是通过spring.factories配置文件,而是通过@EnableZuulProxy注解引入配置的,源码如下:
@EnableCircuitBreaker
@EnableDiscoveryClient
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(ZuulProxyConfiguration.class)
public @interface EnableZuulProxy {
}
  • zuul路由的请求是通过filter发出去的

路由的刷新机制


  • 可刷新的路由定位器(RefreshableRouteLocator)是基于监听spring容器事件实现的,并且都是在配置类中(内部静态类),有两个地方:

ZuulConfiguration中的监听:

//加载bean
@Bean
public ApplicationListener<ApplicationEvent> zuulRefreshRoutesListener() {
    return new ZuulRefreshListener();
}

//内部静态类
private static class ZuulRefreshListener implements ApplicationListener<ApplicationEvent> {

    @Autowired
    private ZuulHandlerMapping zuulHandlerMapping;
    
    private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();
    
    @Override
    public void onApplicationEvent(ApplicationEvent event) {
    	if (event instanceof ContextRefreshedEvent
    			|| event instanceof RefreshScopeRefreshedEvent
    			|| event instanceof RoutesRefreshedEvent) {
            this.zuulHandlerMapping.setDirty(true);
    	}
    	else if (event instanceof HeartbeatEvent) {
            if (this.heartbeatMonitor.update(((HeartbeatEvent) event).getValue())) {
                this.zuulHandlerMapping.setDirty(true);
            }
    	}
    }
    
}

ZuulProxyConfiguration中的监听:

//加载bean
@Bean
public ApplicationListener<ApplicationEvent> zuulDiscoveryRefreshRoutesListener() {
    return new ZuulDiscoveryRefreshListener();
}

//内部静态类
private static class ZuulDiscoveryRefreshListener implements ApplicationListener<ApplicationEvent> {

    private HeartbeatMonitor monitor = new HeartbeatMonitor();
    
    @Autowired
    private ZuulHandlerMapping zuulHandlerMapping;
    
    @Override
    public void onApplicationEvent(ApplicationEvent event) {
        if (event instanceof InstanceRegisteredEvent) {
            reset();
        }
        else if (event instanceof ParentHeartbeatEvent) {
            ParentHeartbeatEvent e = (ParentHeartbeatEvent) event;
            resetIfNeeded(e.getValue());
        }
        else if (event instanceof HeartbeatEvent) {
            HeartbeatEvent e = (HeartbeatEvent) event;
            resetIfNeeded(e.getValue());
        }
    
    }
    
    private void resetIfNeeded(Object value) {
    	if (this.monitor.update(value)) {
            reset();
    	}
    }
    
    private void reset() {
        this.zuulHandlerMapping.setDirty(true);
    }
}

以上可以看出有个问题,两个地方都监听了HeartbeatEvent,并且做了相同的处理,会导致重复刷新

  • 触发心跳事件:SimpleApplicationEventMulticaster-->167行
  • 心跳是个线程池专门处理,初始化是在:com.netflix.discovery.DiscoveryClient-->1247行
  • 心跳的间隔时间配置有bug(配置没生效,配置的名称是间隔,但是线程池调度的时候传给超时时间的),默认是30分钟,配置是:
#org.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean.leaseRenewalIntervalInSeconds
eureka.instance.leaseRenewalIntervalInSeconds=30
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