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标签:reg   ipaddress   min   smart   col   bubuko   system   负载均衡。   support   

在Riibon中一个非常重要的组件为LoadBalancerClient,它作为负载均衡的一个客户端

ServiceInstance choose(String serviceId);    从负载均衡器中挑选一个对应服务的实例

技术分享图片

choose 调用到getserver

protected Server getServer(ILoadBalancer loadBalancer) {
        if (loadBalancer == null) {
            return null;
        }
        return loadBalancer.chooseServer("default"); // TODO: better handling of key
    }

ILoadBalancer在ribbon-loadbalancer的jar包下,它是定义了实现软件负载均衡的一个接口,它需要一组可供选择的服务注册列表信息,以及根据特定方法去选择服务,

public interface ILoadBalancer {

    public void addServers(List<Server> newServers);
    public Server chooseServer(Object key);
    public void markServerDown(Server server);
    public List<Server> getReachableServers();
    public List<Server> getAllServers();
}

实现类为DynamicServerListLoadBalancer

构造传入

    public DynamicServerListLoadBalancer(IClientConfig clientConfig, IRule rule, IPing ping,
                                         ServerList<T> serverList, ServerListFilter<T> filter,
                                         ServerListUpdater serverListUpdater) {
        super(clientConfig, rule, ping);
        this.serverListImpl = serverList;
        this.filter = filter;
        this.serverListUpdater = serverListUpdater;
        if (filter instanceof AbstractServerListFilter) {
            ((AbstractServerListFilter) filter).setLoadBalancerStats(getLoadBalancerStats());
        }
        restOfInit(clientConfig);
    }
  • IClientConfig ribbonClientConfig: DefaultClientConfigImpl配置
  • IRule ribbonRule: RoundRobinRule 路由策略
  • IPing ribbonPing: DummyPing  检查是否活着
  • ServerList ribbonServerList: ConfigurationBasedServerList  定义获取所有的server的注册列表信息的接口
  • ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter   可根据配置去过滤或者根据特性动态获取符合条件的server列表的方法
  • ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
 void restOfInit(IClientConfig clientConfig) {
        boolean primeConnection = this.isEnablePrimingConnections();
        // turn this off to avoid duplicated asynchronous priming done in BaseLoadBalancer.setServerList()
        this.setEnablePrimingConnections(false);
        enableAndInitLearnNewServersFeature();

        updateListOfServers();
        if (primeConnection && this.getPrimeConnections() != null) {
            this.getPrimeConnections()
                    .primeConnections(getReachableServers());
        }
        this.setEnablePrimingConnections(primeConnection);
        LOGGER.info("DynamicServerListLoadBalancer for client {} initialized: {}", clientConfig.getClientName(), this.toString());
    }
继续追踪是在这里通过EurekaClient找到服务列表,EurekaClient的实现类为DiscoveryClient,它具有服务注册、获取服务注册列表等的全部功能  由此可见,
负载均衡器是从EurekaClient获取服务信息,并根据IRule去路由,并且根据IPing去判断服务的可用性

private List<DiscoveryEnabledServer> obtainServersViaDiscovery() { List<DiscoveryEnabledServer> serverList = new ArrayList<DiscoveryEnabledServer>(); if (eurekaClientProvider == null || eurekaClientProvider.get() == null) { logger.warn("EurekaClient has not been initialized yet, returning an empty list"); return new ArrayList<DiscoveryEnabledServer>(); } EurekaClient eurekaClient = eurekaClientProvider.get(); if (vipAddresses!=null){ for (String vipAddress : vipAddresses.split(",")) { // if targetRegion is null, it will be interpreted as the same region of client List<InstanceInfo> listOfInstanceInfo = eurekaClient.getInstancesByVipAddress(vipAddress, isSecure, targetRegion); for (InstanceInfo ii : listOfInstanceInfo) { if (ii.getStatus().equals(InstanceStatus.UP)) { if(shouldUseOverridePort){ if(logger.isDebugEnabled()){ logger.debug("Overriding port on client name: " + clientName + " to " + overridePort); } // copy is necessary since the InstanceInfo builder just uses the original reference, // and we don‘t want to corrupt the global eureka copy of the object which may be // used by other clients in our system InstanceInfo copy = new InstanceInfo(ii); if(isSecure){ ii = new InstanceInfo.Builder(copy).setSecurePort(overridePort).build(); }else{ ii = new InstanceInfo.Builder(copy).setPort(overridePort).build(); } } DiscoveryEnabledServer des = new DiscoveryEnabledServer(ii, isSecure, shouldUseIpAddr); des.setZone(DiscoveryClient.getZone(ii)); serverList.add(des); } } if (serverList.size()>0 && prioritizeVipAddressBasedServers){ break; // if the current vipAddress has servers, we dont use subsequent vipAddress based servers } } } return serverList; }

由此可见,负载均衡器是从EurekaClient获取服务信息,并根据IRule去路由,并且根据IPing去判断服务的可用性。

负载均衡器多久ping一次呢BaseLoadBalancer

LoadBalancerClient会在初始化会向Eureka拉取服务注册列表,并且向通过10s一次向EurekaClient发送“ping”,来判断服务的可用性,如果服务的可用性发生了改变或者服务数量和之前的不一致,则更新或者重新拉取。LoadBalancerClient有了这些服务注册列表,就可以根据具体的IRule来进行负载均衡。

LoadBalancerAutoConfiguration 中会对RestTemplate进行定制

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

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

    @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);
                }
            }
        });
    }

    @Autowired(required = false)
    private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();

    @Bean
    @ConditionalOnMissingBean
    public LoadBalancerRequestFactory loadBalancerRequestFactory(
            LoadBalancerClient loadBalancerClient) {
        return new LoadBalancerRequestFactory(loadBalancerClient, transformers);
    }

    @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);
            };
        }
    }
RestTemplateCustomizer  定制器调用 customizer.customize(restTemplate)
在该类中,首先维护了一个被@LoadBalanced修饰的RestTemplate对象的List,在初始化的过程中,通过调用customizer.customize(restTemplate)方法来给RestTemplate增加
拦截器LoadBalancerInterceptor。

而LoadBalancerInterceptor,用于实时拦截,在LoadBalancerInterceptor这里实现来负载均衡。LoadBalancerInterceptor的拦截方法如下:
@Override
    public ClientHttpResponse intercept(final HttpRequest request, final byte[] body,
            final ClientHttpRequestExecution execution) throws IOException {
        final URI originalUri = request.getURI();
        String serviceName = originalUri.getHost();
        Assert.state(serviceName != null, "Request URI does not contain a valid hostname: " + originalUri);
        return this.loadBalancer.execute(serviceName, requestFactory.createRequest(request, body, execution));
    }

综上所述,Ribbon的负载均衡,主要通过LoadBalancerClient来实现的,而LoadBalancerClient具体交给了ILoadBalancer来处理,ILoadBalancer通过配置IRule、IPing等信息,并向EurekaClient获取注册列表的信息,并默认10秒一次向EurekaClient发送“ping”,进而检查是否更新服务列表,最后,得到注册列表后,ILoadBalancer根据IRule的策略进行负载均衡。

而RestTemplate 被@LoadBalance注解后,能过用负载均衡,主要是维护了一个被@LoadBalance注解的RestTemplate列表,并给列表中的RestTemplate添加拦截器,进而交给负载均衡器去处理。

Ribbon源

标签:reg   ipaddress   min   smart   col   bubuko   system   负载均衡。   support   

原文地址:https://www.cnblogs.com/mxz1994/p/9844582.html

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