Dubbo源码分析之提供端（2）

获取注册URL，还原原来的协议，因为设置的临时协议只是为了导向到该类。


private URL getRegistryUrl(Invoker<?> originInvoker) {
    URL registryUrl = originInvoker.getUrl();
    if (REGISTRY_PROTOCOL.equals(registryUrl.getProtocol())) {
        String protocol = registryUrl.getParameter(REGISTRY_KEY, DEFAULT_DIRECTORY);
        registryUrl = registryUrl.setProtocol(protocol).removeParameter(REGISTRY_KEY);
    }
    return registryUrl;
}

获取提供者URL，之前该URL被当做参数设置到注册URL上。

private URL getProviderUrl(final Invoker<?> originInvoker) {
    String export = originInvoker.getUrl().getParameterAndDecoded(EXPORT_KEY);
    if (export == null || export.length() == 0) {
        throw new IllegalArgumentException("The registry export url is null! registry: " + originInvoker.getUrl());
    }
    return URL.valueOf(export);
}

暴露本地代理invoker

private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker, URL providerUrl) {
    String key = getCacheKey(originInvoker);

    return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {
        Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);
        return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);
    });
}

private String getCacheKey(final Invoker<?> originInvoker) {
    URL providerUrl = getProviderUrl(originInvoker);
    String key = providerUrl.removeParameters("dynamic", "enabled").toFullString();
    return key;
}

提供者URL默认为dubbo协议，这次也会走那三个包装类，QosProtocolWrapper

不做处理，ProtocolFilterWrapper对代理进行过滤器包装，他会获取提供端组设置的所有需要激活的过滤器类，ProtocolListenerWrapper获取URL中设置的和自动激活的监听器类。

private static <T> Invoker<T> buildInvokerChain(final Invoker<T> invoker, String key, String group) {
    Invoker<T> last = invoker;
    List<Filter> filters = ExtensionLoader.getExtensionLoader(Filter.class).getActivateExtension(invoker.getUrl(), key, group);
    if (!filters.isEmpty()) {
        for (int i = filters.size() - 1; i >= 0; i--) {
            final Filter filter = filters.get(i);
            final Invoker<T> next = last;
            last = new Invoker<T>() {

                @Override
                public Class<T> getInterface() {
                    return invoker.getInterface();
                }

                @Override
                public URL getUrl() {
                    return invoker.getUrl();
                }

                @Override
                public boolean isAvailable() {
                    return invoker.isAvailable();
                }

                @Override
                public Result invoke(Invocation invocation) throws RpcException {
                    Result result = filter.invoke(next, invocation);
                    if (result instanceof AsyncRpcResult) {
                        AsyncRpcResult asyncResult = (AsyncRpcResult) result;
                        asyncResult.thenApplyWithContext(r -> filter.onResponse(r, invoker, invocation));
                        return asyncResult;
                    } else {
                        return filter.onResponse(result, invoker, invocation);
                    }
                }

                @Override
                public void destroy() {
                    invoker.destroy();
                }

                @Override
                public String toString() {
                    return invoker.toString();
                }
            };
        }
    }
    return last;
}

通过dubbo协议暴露服务，获取具体的提供端URL，组装dubbo暴露者类

public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
    URL url = invoker.getUrl();

    // export service.
    String key = serviceKey(url);
    DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
    exporterMap.put(key, exporter);

    //export an stub service for dispatching event
    Boolean isStubSupportEvent = url.getParameter(Constants.STUB_EVENT_KEY, Constants.DEFAULT_STUB_EVENT);
    Boolean isCallbackservice = url.getParameter(Constants.IS_CALLBACK_SERVICE, false);
    if (isStubSupportEvent && !isCallbackservice) {
        String stubServiceMethods = url.getParameter(Constants.STUB_EVENT_METHODS_KEY);
        if (stubServiceMethods == null || stubServiceMethods.length() == 0) {
            if (logger.isWarnEnabled()) {
                logger.warn(new IllegalStateException("consumer [" + url.getParameter(Constants.INTERFACE_KEY) +
                        "], has set stubproxy support event ,but no stub methods founded."));
            }

        } else {
            stubServiceMethodsMap.put(url.getServiceKey(), stubServiceMethods);
        }
    }

    openServer(url);
    optimizeSerialization(url);

    return exporter;
}

组装服务key，由服务组名，服务类名，版本号以及端口组成


protected static String serviceKey(URL url) {
    int port = url.getParameter(Constants.BIND_PORT_KEY, url.getPort());
    return serviceKey(port, url.getPath(), url.getParameter(Constants.VERSION_KEY),
            url.getParameter(Constants.GROUP_KEY));
}

protected static String serviceKey(int port, String serviceName, String serviceVersion, String serviceGroup) {
    return ProtocolUtils.serviceKey(port, serviceName, serviceVersion, serviceGroup);
}

public static String serviceKey(int port, String serviceName, String serviceVersion, String serviceGroup) {
    StringBuilder buf = new StringBuilder();
    if (StringUtils.isNotEmpty(serviceGroup)) {
        buf.append(serviceGroup);
        buf.append("/");
    }
    buf.append(serviceName);
    if (serviceVersion != null && serviceVersion.length() > 0 && !"0.0.0".equals(serviceVersion)) {
        buf.append(":");
        buf.append(serviceVersion);
    }
    buf.append(":");
    buf.append(port);
    return buf.toString();
}

接收消费端的请求，所以需要启动服务端

private void openServer(URL url) {
    // find server.
    String key = url.getAddress();
    //client can export a service which's only for server to invoke
    boolean isServer = url.getParameter(Constants.IS_SERVER_KEY, true);
    if (isServer) {
        ExchangeServer server = serverMap.get(key);
        if (server == null) {
            synchronized (this) {
                server = serverMap.get(key);
                if (server == null) {
                    serverMap.put(key, createServer(url));
                }
            }
        } else {
            // server supports reset, use together with override
            server.reset(url);
        }
    }
}

二重检查后创建交换服务端，设置心跳时间以及编码协议

private ExchangeServer createServer(URL url) {
    url = URLBuilder.from(url)
            // send readonly event when server closes, it's enabled by default
            .addParameterIfAbsent(Constants.CHANNEL_READONLYEVENT_SENT_KEY, Boolean.TRUE.toString())
            // enable heartbeat by default
            .addParameterIfAbsent(Constants.HEARTBEAT_KEY, String.valueOf(Constants.DEFAULT_HEARTBEAT))
            .addParameter(Constants.CODEC_KEY, DubboCodec.NAME)
            .build();
    String str = url.getParameter(Constants.SERVER_KEY, Constants.DEFAULT_REMOTING_SERVER);

    if (str != null && str.length() > 0 && !ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str)) {
        throw new RpcException("Unsupported server type: " + str + ", url: " + url);
    }

    ExchangeServer server;
    try {
        server = Exchangers.bind(url, requestHandler);
    } catch (RemotingException e) {
        throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
    }

    str = url.getParameter(Constants.CLIENT_KEY);
    if (str != null && str.length() > 0) {
        Set<String> supportedTypes = ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions();
        if (!supportedTypes.contains(str)) {
            throw new RpcException("Unsupported client type: " + str);
        }
    }

    return server;
}

获取对应的交换器，默认为header，即HeaderExchanger

public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
    if (url == null) {
        throw new IllegalArgumentException("url == null");
    }
    if (handler == null) {
        throw new IllegalArgumentException("handler == null");
    }
    url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
    return getExchanger(url).bind(url, handler);
}

public static Exchanger getExchanger(URL url) {
    String type = url.getParameter(Constants.EXCHANGER_KEY, Constants.DEFAULT_EXCHANGER);
    return getExchanger(type);
}

public static Exchanger getExchanger(String type) {
    return ExtensionLoader.getExtensionLoader(Exchanger.class).getExtension(type);
}

Dubbo源码分析之提供端（2）

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