package com.alibaba.dubbo.rpc.cluster.support;

/**

 * 失败转移，当出现失败，重试其它服务器，通常用于读操作，但重试会带来更长延迟。

 *

 * <a href="http://en.wikipedia.org/wiki/Failover">Failover</a>

 *

 * @author william.liangf

 * @author chao.liuc

 */

public class FailoverClusterInvoker<T> extends AbstractClusterInvoker<T> {

    private static final Logger logger = LoggerFactory.getLogger(FailoverClusterInvoker.class);

    public FailoverClusterInvoker(Directory<T> directory) {

        super(directory);

    }

    @SuppressWarnings({ "unchecked", "rawtypes" })

    public Result doInvoke(Invocation invocation, final List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {

        List<Invoker<T>> copyinvokers = invokers;

        checkInvokers(copyinvokers, invocation);

        int len = getUrl().getMethodParameter(invocation.getMethodName(), Constants.RETRIES_KEY, Constants.DEFAULT_RETRIES) + 1;

        if (len <= 0) {

            len = 1;

        }

        // retry loop.

        RpcException le = null; // last exception.

        List<Invoker<T>> invoked = new ArrayList<Invoker<T>>(copyinvokers.size()); // invoked invokers.

        Set<String> providers = new HashSet<String>(len);

        for (int i = 0; i < len; i++) {

            //重试时，进行重新选择，避免重试时invoker列表已发生变化.

            //注意：如果列表发生了变化，那么invoked判断会失效，因为invoker示例已经改变

            if (i > 0) {

                checkWheatherDestoried();

                copyinvokers = list(invocation);

                //重新检查一下

                checkInvokers(copyinvokers, invocation);

            }

            Invoker<T> invoker = select(loadbalance, invocation, copyinvokers, invoked);

            invoked.add(invoker);

            RpcContext.getContext().setInvokers((List)invoked);

            try {

                Result result = invoker.invoke(invocation);

                if (le != null && logger.isWarnEnabled()) {

                    logger.warn("Although retry the method " + invocation.getMethodName()

                            + " in the service " + getInterface().getName()

                            + " was successful by the provider " + invoker.getUrl().getAddress()

                            + ", but there have been failed providers " + providers

                            + " (" + providers.size() + "/" + copyinvokers.size()

                            + ") from the registry " + directory.getUrl().getAddress()

                            + " on the consumer " + NetUtils.getLocalHost()

                            + " using the dubbo version " + Version.getVersion() + ". Last error is: "

                            + le.getMessage(), le);

                }

                return result;

            } catch (RpcException e) {

                if (e.isBiz()) { // biz exception.

                    throw e;

                }

                le = e;

            } catch (Throwable e) {

                le = new RpcException(e.getMessage(), e);

            } finally {

                providers.add(invoker.getUrl().getAddress());

            }

        }

        throw new RpcException(le != null ? le.getCode() : 0, "Failed to invoke the method "

                + invocation.getMethodName() + " in the service " + getInterface().getName()

                + ". Tried " + len + " times of the providers " + providers

                + " (" + providers.size() + "/" + copyinvokers.size()

                + ") from the registry " + directory.getUrl().getAddress()

                + " on the consumer " + NetUtils.getLocalHost() + " using the dubbo version "

                + Version.getVersion() + ". Last error is: "

                + (le != null ? le.getMessage() : ""), le != null && le.getCause() != null ? le.getCause() : le);

    }

}

java.util.concurrent.ExecutionException: com.alibaba.dubbo.rpc.RpcException: 
Failed to invoke the method query in the service cn.fraudmetrix.skuld.api.client.intf.IListValueService. 
Tried 1 times of the providers [192.168.121.230:20880] (1/10) from the registry 192.168.47.83:2181 on the consumer 192.168.55.67 
using the dubbo version 2.5.3. Last error is: null

Failed to invoke the method query in the service cn.fraudmetrix.skuld.api.client.intf.IListValueService. 
Tried 3 times of the providers [10.57.240.10:20880] (1/1) from the registry 192.168.6.55:2181 on the consumer 10.57.240.10 
using the dubbo version 2.5.3. Last error is: 
Invoke remote method timeout. method: query, provider: dubbo://10.57.240.10:20880/....

om.alibaba.dubbo.rpc.RpcException: Forbid consumer 10.57.240.10 access service cn.fraudmetrix.skuld.api.client.intf.IListValueService from registry 192.168.6.55:2181 use dubbo version 2.5.3, Please check registry access list (whitelist/blacklist).

    at com.alibaba.dubbo.registry.integration.RegistryDirectory.doList(RegistryDirectory.java:579)

    at com.alibaba.dubbo.rpc.cluster.directory.AbstractDirectory.list(AbstractDirectory.java:73)

    at com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker.list(AbstractClusterInvoker.java:260)

    at com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:219)

    at com.alibaba.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:72)

    at com.alibaba.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:52)

    at com.alibaba.dubbo.common.bytecode.proxy0.query(proxy0.java)

    at cn.fraudmetrix.skuld.dubbotest.ValueQueryTest.runTest(ValueQueryTest.java:70)

    at cn.fraudmetrix.skuld.dubbotest.App.main(App.java:15)

Failed to invoke the method query in the service cn.fraudmetrix.skuld.api.client.intf.IListValueService. 
Tried 3 times of the providers [10.57.240.10:20880] (1/1) from the registry 192.168.6.55:2181 on the consumer 10.57.240.10 
using the dubbo version 2.5.3. Last error is: 
Failed to invoke remote method: query, provider: dubbo://10.57.240.10:20880/.....