Ribbon源码分析ILoadBalancer

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7Ribbon源码分析ILoadBalancer

ILoadBalancer

public interface ILoadBalancer {

   /**
    * Initial list of servers.
    * This API also serves to add additional ones at a later time
    * The same logical server (host:port) could essentially be added multiple times
    * (helpful in cases where you want to give more "weightage" perhaps ..)
    * 
    * @param newServers new servers to add
    */
   public void addServers(List<Server> newServers);
   
   /**
    * Choose a server from load balancer.
    * 
    * @param key An object that the load balancer may use to determine which server to return. null if 
    *         the load balancer does not use this parameter.
    * @return server chosen
    */
   public Server chooseServer(Object key);
   
   /**
    * To be called by the clients of the load balancer to notify that a Server is down
    * else, the LB will think its still Alive until the next Ping cycle - potentially
    * (assuming that the LB Impl does a ping)
    * 
    * @param server Server to mark as down
    */
   public void markServerDown(Server server);
   
   /**
    * @deprecated 2016-01-20 This method is deprecated in favor of the
    * cleaner {@link #getReachableServers} (equivalent to availableOnly=true)
    * and {@link #getAllServers} API (equivalent to availableOnly=false).
    *
    * Get the current list of servers.
    *
    * @param availableOnly if true, only live and available servers should be returned
    */
   @Deprecated
   public List<Server> getServerList(boolean availableOnly);

   /**
    * @return Only the servers that are up and reachable.
     */
    public List<Server> getReachableServers();

    /**
     * @return All known servers, both reachable and unreachable.
     */
   public List<Server> getAllServers();
}

• addServers：向负载均衡器中维护的实例列表增加服务实例
• chooseServer：通过某种策略，从负载均衡器中挑选出一个具体的服务实例。
• markServerDown：用来通知和标识负载均衡器中某个具体实例已经停止服务，不然负载均衡器在下一次获取服务实例清单前都会认为服务实例均是正常服务
• getReachableServers：获取当前正常服务的实例列表
• getAllServers：获取所有已知服务实例列表，包括正常服务和停止服务的实例

通过RibbonClientConfiguration：

@Bean
@ConditionalOnMissingBean
public ILoadBalancer ribbonLoadBalancer(IClientConfig config,
      ServerList<Server> serverList, ServerListFilter<Server> serverListFilter,
      IRule rule, IPing ping) {
   ZoneAwareLoadBalancer<Server> balancer = LoadBalancerBuilder.newBuilder()
         .withClientConfig(config).withRule(rule).withPing(ping)
         .withServerListFilter(serverListFilter).withDynamicServerList(serverList)
         .buildDynamicServerListLoadBalancer();
   return balancer;
}

可以知道使用实现类为ZoneAwareLoadBalancer