Failfast Cluster

快速失敗，只發起一次呼叫，失敗立即報錯。通常用於非冪等性的寫操作，比如新增記錄。

在FailfastCluster中是通過建立一個FailfastClusterInvoker來完成一次呼叫失敗報錯機制的。

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中簡單來說就是通過負載均衡查詢服務提供者，呼叫服務提供提供者，如果失敗則返回失敗結果

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);
		//負載均衡查詢服務提供者
        Invoker<T> invoker = select(loadbalance, invocation, invokers, null);
        try {
			//呼叫服務
            return invoker.invoke(invocation);
        } catch (Throwable e) {
			//失敗返回異常資訊
            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);
        }
    }
}