Dubbo源代码分析_接收调用并服务代码

DubboProtocol 中的成员变量requestHandler就是用来处理rpc请求的.
rpc请求是在netty的worker thread中执行的

public class DubboProtocol extends AbstractProtocol {
    private final Map<String, ExchangeServer> serverMap = new ConcurrentHashMap<String, ExchangeServer>(); // <host:port,Exchanger>
    private final Map<String, ReferenceCountExchangeClient> referenceClientMap = new ConcurrentHashMap<String, ReferenceCountExchangeClient>(); // <host:port,Exchanger>
    private final ConcurrentMap<String, LazyConnectExchangeClient> ghostClientMap = new ConcurrentHashMap<String, LazyConnectExchangeClient>();
    //consumer side export a stub service for dispatching event
    //servicekey-stubmethods
    private final ConcurrentMap<String, String> stubServiceMethodsMap = new ConcurrentHashMap<String, String>();
    private ExchangeHandler requestHandler = new ExchangeHandlerAdapter() {

        public Object reply(ExchangeChannel channel, Object message) throws RemotingException {
            if (message instanceof Invocation) {
                Invocation inv = (Invocation) message;
                //得到invoker
                Invoker<?> invoker = getInvoker(channel, inv);
                //如果是callback 需要处理高版本调用低版本的问题
                if (Boolean.TRUE.toString().equals(inv.getAttachments().get(IS_CALLBACK_SERVICE_INVOKE))) {
                    String methodsStr = invoker.getUrl().getParameters().get("methods");
                    boolean hasMethod = false;
                    if (methodsStr == null || methodsStr.indexOf(",") == -1) {
                        hasMethod = inv.getMethodName().equals(methodsStr);
                    } else {
                        String[] methods = methodsStr.split(",");
                        for (String method : methods) {
                            if (inv.getMethodName().equals(method)) {
                                hasMethod = true;
                                break;
                            }
                        }
                    }
                    if (!hasMethod) {
                        logger.warn(new IllegalStateException("The methodName " + inv.getMethodName() + " not found in callback service interface ,invoke will be ignored. please update the api interface. url is:" + invoker.getUrl()) + " ,invocation is :" + inv);
                        return null;
                    }
                }
                //设置远程地址
          RpcContext.getContext().setRemoteAddress(channel.getRemoteAddress());
                return invoker.invoke(inv);
            }
            //不支持所有格式的请求
            throw new RemotingException(channel, "Unsupported request: " + message == null ? null : (message.getClass().getName() + ": " + message) + ", channel: consumer: " + channel.getRemoteAddress() + " --> provider: " + channel.getLocalAddress());
        }

        @Override
        public void received(Channel channel, Object message) throws RemotingException {
            if (message instanceof Invocation) {
                reply((ExchangeChannel) channel, message);
            } else {
                super.received(channel, message);
            }
        }

        @Override
        public void connected(Channel channel) throws RemotingException {
            invoke(channel, Constants.ON_CONNECT_KEY);
        }

        @Override
        public void disconnected(Channel channel) throws RemotingException {
            if (logger.isInfoEnabled()) {
                logger.info("disconected from " + channel.getRemoteAddress() + ",url:" + channel.getUrl());
            }
            invoke(channel, Constants.ON_DISCONNECT_KEY);
        }

        private void invoke(Channel channel, String methodKey) {
            Invocation invocation = createInvocation(channel, channel.getUrl(), methodKey);
            if (invocation != null) {
                try {
                    received(channel, invocation);
                } catch (Throwable t) {
                    logger.warn("Failed to invoke event method " + invocation.getMethodName() + "(), cause: " + t.getMessage(), t);
                }
            }
        }

        private Invocation createInvocation(Channel channel, URL url, String methodKey) {
            String method = url.getParameter(methodKey);
            if (method == null || method.length() == 0) {
                return null;
            }
            RpcInvocation invocation = new RpcInvocation(method, new Class<?>[0], new Object[0]);
            invocation.setAttachment(Constants.PATH_KEY, url.getPath());
            invocation.setAttachment(Constants.GROUP_KEY, url.getParameter(Constants.GROUP_KEY));
            invocation.setAttachment(Constants.INTERFACE_KEY, url.getParameter(Constants.INTERFACE_KEY));
            invocation.setAttachment(Constants.VERSION_KEY, url.getParameter(Constants.VERSION_KEY));
            if (url.getParameter(Constants.STUB_EVENT_KEY, false)) {
                invocation.setAttachment(Constants.STUB_EVENT_KEY, Boolean.TRUE.toString());
            }
            return invocation;
        }
    };


    Invoker<?> getInvoker(Channel channel, Invocation inv) throws RemotingException {
        boolean isCallBackServiceInvoke = false;
        boolean isStubServiceInvoke = false;
        int port = channel.getLocalAddress().getPort();
        String path = inv.getAttachments().get(Constants.PATH_KEY);
        //如果是客户端的回调服务.
        isStubServiceInvoke = Boolean.TRUE.toString().equals(inv.getAttachments().get(Constants.STUB_EVENT_KEY));
        if (isStubServiceInvoke) {
            port = channel.getRemoteAddress().getPort();
        }
        //callback
        isCallBackServiceInvoke = isClientSide(channel) && !isStubServiceInvoke;
        if (isCallBackServiceInvoke) {
            path = inv.getAttachments().get(Constants.PATH_KEY) + "." + inv.getAttachments().get(Constants.CALLBACK_SERVICE_KEY);
            inv.getAttachments().put(IS_CALLBACK_SERVICE_INVOKE, Boolean.TRUE.toString());
        }
        String serviceKey = serviceKey(port, path, inv.getAttachments().get(Constants.VERSION_KEY), inv.getAttachments().get(Constants.GROUP_KEY));

        DubboExporter<?> exporter = (DubboExporter<?>) exporterMap.get(serviceKey);

        if (exporter == null)
            throw new RemotingException(channel, "Not found exported service: " + serviceKey + " in " + exporterMap.keySet() + ", may be version or group mismatch " + ", channel: consumer: " + channel.getRemoteAddress() + " --> provider: " + channel.getLocalAddress() + ", message:" + inv);

        return exporter.getInvoker();
    }
 
}

在暴露服务的时候,会将invoker放入到exporterMap中. 后续就可以根据invocation的serviceKey得到invoker.

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 dispaching 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);

        return exporter;
    }

通过invocation调用invoker的invoker方法.其中参数,都是可以从invocation中获取到.

public abstract class AbstractProxyInvoker<T> implements Invoker<T> {

    private final T proxy;

    private final Class<T> type;

    private final URL url;

    public AbstractProxyInvoker(T proxy, Class<T> type, URL url) {
        if (proxy == null) {
            throw new IllegalArgumentException("proxy == null");
        }
        if (type == null) {
            throw new IllegalArgumentException("interface == null");
        }
        if (!type.isInstance(proxy)) {
            throw new IllegalArgumentException(proxy.getClass().getName() + " not implement interface " + type);
        }
        this.proxy = proxy;
        this.type = type;
        this.url = url;
    }

    public Class<T> getInterface() {
        return type;
    }

    public URL getUrl() {
        return url;
    }

    public boolean isAvailable() {
        return true;
    }

    public void destroy() {
    }

    public Result invoke(Invocation invocation) throws RpcException {
        try {
            return new RpcResult(doInvoke(proxy, invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments()));
        } catch (InvocationTargetException e) {
            return new RpcResult(e.getTargetException());
        } catch (Throwable e) {
            throw new RpcException("Failed to invoke remote proxy method " + invocation.getMethodName() + " to " + getUrl() + ", cause: " + e.getMessage(), e);
        }
    }

    protected abstract Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable;
	
}

暴露服务时创建出来的invoker的核心代码:

public class JdkProxyFactory extends AbstractProxyFactory {

    @SuppressWarnings("unchecked")
    public <T> T getProxy(Invoker<T> invoker, Class<?>[] interfaces) {
        return (T) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), interfaces, new InvokerInvocationHandler(invoker));
    }

    public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) {
        return new AbstractProxyInvoker<T>(proxy, type, url) {
            @Override
            protected Object doInvoke(T proxy, String methodName,
                                      Class<?>[] parameterTypes,
                                      Object[] arguments) throws Throwable {
                Method method = proxy.getClass().getMethod(methodName, parameterTypes);
                return method.invoke(proxy, arguments);
            }
        };
    }

}

粘贴一下invocation的定义:

public interface Invocation {

    /**
     * get method name.
     *
     * @return method name.
     * @serial
     */
    String getMethodName();

    /**
     * get parameter types.
     *
     * @return parameter types.
     * @serial
     */
    Class<?>[] getParameterTypes();

    /**
     * get arguments.
     *
     * @return arguments.
     * @serial
     */
    Object[] getArguments();

    /**
     * get attachments.
     *
     * @return attachments.
     * @serial
     */
    Map<String, String> getAttachments();

    /**
     * get attachment by key.
     *
     * @return attachment value.
     * @serial
     */
    String getAttachment(String key);

    /**
     * get attachment by key with default value.
     *
     * @return attachment value.
     * @serial
     */
    String getAttachment(String key, String defaultValue);

    /**
     * get the invoker in current context.
     *
     * @return invoker.
     * @transient
     */
    Invoker<?> getInvoker();

}