Dubb源码学习--FailfastCluster集群容错（五）

布满荆棘的人生 2022-05-28 01:24 47阅读 0赞

### Failfast Cluster ###

快速失败，只发起一次调用，失败立即报错。通常用于非幂等性的写操作，比如新增记录。

在FailfastCluster中是通过创建一个FailfastClusterInvoker来完成一次调用失败报错机制的。

public class FailfastCluster implements Cluster {
    
        public final static String NAME = "failfast";
    
        public <T> Invoker<T> join(Directory<T> directory) throws RpcException {
            return new FailfastClusterInvoker<T>(directory);
        }
    
    }

FailfastClusterInvoker中简单来说就是通过负载均衡查找服务提供者，调用服务提供提供者，如果失败则返回失败结果

public class FailfastClusterInvoker<T> extends AbstractClusterInvoker<T> {
    
        public FailfastClusterInvoker(Directory<T> directory) {
            super(directory);
        }
    
        public Result doInvoke(Invocation invocation, List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {
            checkInvokers(invokers, invocation);
    		//负载均衡查找服务提供者
            Invoker<T> invoker = select(loadbalance, invocation, invokers, null);
            try {
    			//调用服务
                return invoker.invoke(invocation);
            } catch (Throwable e) {
    			//失败返回异常信息
                if (e instanceof RpcException && ((RpcException) e).isBiz()) { // biz exception.
                    throw (RpcException) e;
                }
                throw new RpcException(e instanceof RpcException ? ((RpcException) e).getCode() : 0, "Failfast invoke providers " + invoker.getUrl() + " " + loadbalance.getClass().getSimpleName() + " select from all providers " + invokers + " for service " + getInterface().getName() + " method " + invocation.getMethodName() + " on consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion() + ", but no luck to perform the invocation. Last error is: " + e.getMessage(), e.getCause() != null ? e.getCause() : e);
            }
        }
    }