Dubbo学习总结(十一)dubbo服务调用流程

╰半夏微凉° 2024-02-19 15:42 70阅读 0赞

**服务调用流程：**

![/dev-guide/images/dubbo-extension.jpg][dev-guide_images_dubbo-extension.jpg]

服务的调用采用了代理模式，其代理对象是通过ProxyFactory生成的。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1][]

执行

invoker.invoke(new RpcInvocation(method, args)).recreate()。

进入到MockClusterInvoker（失败重试机制）：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 2][]

执行invoke方法，先进入AbstractClusterInvoker类查找注册中心注册代理类和负载均衡策略：

@Override
        public Result invoke(final Invocation invocation) throws RpcException {
            checkWhetherDestroyed();
            LoadBalance loadbalance = null;
    		//从注册中心获取该方法对应的代理对象
            List<Invoker<T>> invokers = list(invocation);
            if (invokers != null && !invokers.isEmpty()) {
    		    // 获取负载均衡机制
                loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
                        .getMethodParameter(invocation.getMethodName(), Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
            }
            RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
            return doInvoke(invocation, invokers, loadbalance);
        }

执行doInvoke()方法，根据失败策略确定执行哪一个Invoker类根据上述此处执行FailoverClusterInvoker.doInvoke（）方法。

*  Failover Cluster - 失败自动切换
 *  Failfast Cluster - 快速失败
 *  Failsafe Cluster - 失败安全
 *  Failback Cluster - 失败自动恢复
 *  Forking Cluster - 并行调用多个服务提供者

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 3][]

FailoverClusterInvoker.doInvoke（）：

@Override
        @SuppressWarnings({"unchecked", "rawtypes"})
        public Result doInvoke(Invocation invocation, final List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {
                 。。。。。。。。。。。。。。
    			 //根据负载均衡策略获取代理对象
                Invoker<T> invoker = select(loadbalance, invocation, copyinvokers, invoked);
                invoked.add(invoker);
                RpcContext.getContext().setInvokers((List) invoked);
                try {
    			    //执行 根据代理执行方法获取最终的结果
                    Result result = invoker.invoke(invocation);
                    。。。。。。。。。。。。。。。
                    return result;
               。。。。。。。。。。。。。。
        }

在执行最终方法的时候，dubbo有提供了很多的filter进行数据处理如缓存，监听等拦截器。

根据图可以看出存在多个拦截器：ProtocolFilterWrapper

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 4][]

进入：MonitorFilter

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 5][]

最终会进入DubboInvoker连接客户端发送请求：

执行：

@Override
        public ResponseFuture request(Object request, int timeout) throws RemotingException {
            if (closed) {
                throw new RemotingException(this.getLocalAddress(), null, "Failed to send request " + request + ", cause: The channel " + this + " is closed!");
            }
            // create request.
            Request req = new Request();
            req.setVersion("2.0.0");
            req.setTwoWay(true);
            req.setData(request);
            DefaultFuture future = new DefaultFuture(channel, req, timeout);
            try {
                //通道发送数据
                channel.send(req);
            } catch (RemotingException e) {
                future.cancel();
                throw e;
            }
            return future;
        }

得到执行结果返回数据:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 6][]

例如：CacheFilter 缓存

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 7][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 8][]

调试代码：[点击][Link 1]

参考来源：[http://dubbo.apache.org/zh-cn/docs/user/configuration/xml.html][http_dubbo.apache.org_zh-cn_docs_user_configuration_xml.html]

[dev-guide_images_dubbo-extension.jpg]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/81f2e7a4782c414c967ed89f0ef5649d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/92d840e159de45a58c371d7db3f34905.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/73e92f8d502b40288b04c0b61749b4f3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/fc4a962a581b4d6d9a7f00edec55a6d9.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 3]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/9b08628abe60481093778865971abafa.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 4]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/fd526353caea4d30a214ee067f8bb983.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 5]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/08c5e178db5244b8a7b6eead78ad9290.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 6]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/16b11011167d4b1c80e713e4a02f98c6.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 7]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/7d30a1a8a7fb4ad2a22f533ef28e1173.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 8]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/f3a9b44488ce4ea3bb05bc87c606e705.png
[Link 1]: https://github.com/timeday/springboot-dubbo
[http_dubbo.apache.org_zh-cn_docs_user_configuration_xml.html]: http://dubbo.apache.org/zh-cn/docs/user/configuration/xml.html