Dubbo发布过程中,服务端调用过程

接收请求

服务端接收请求以后,我们从一个Handler看起,因为Netty的处理核心为Handler,因为我们找到了InternalDecoder,消息经过处理后,调用了Channels.fireMessageReceived()方法

final class NettyCodecAdapter {
    private final Codec2 codec;
    private class InternalDecoder extends SimpleChannelUpstreamHandler {
        public void messageReceived(ChannelHandlerContext ctx, MessageEvent event) throws Exception {
            //从时间源中获取消息内容  o为BigEndianHeapChannelBuffer类型
            Object o = event.getMessage();
            if (!(o instanceof ChannelBuffer)) {
                ctx.sendUpstream(event);
                return;
            }

            ChannelBuffer input = (ChannelBuffer) o;
            int readable = input.readableBytes();
            if (readable <= 0) {
                return;
            }

            com.alibaba.dubbo.remoting.buffer.ChannelBuffer message;
            if (buffer.readable()) {
                if (buffer instanceof DynamicChannelBuffer) {
                    buffer.writeBytes(input.toByteBuffer());
                    message = buffer;
                } else {
                    int size = buffer.readableBytes() + input.readableBytes();
                    message = com.alibaba.dubbo.remoting.buffer.ChannelBuffers.dynamicBuffer(
                            size > bufferSize ? size : bufferSize);
                    message.writeBytes(buffer, buffer.readableBytes());
                    message.writeBytes(input.toByteBuffer());
                }
            } else {
                //进入此处,对message 进行装饰
                message = com.alibaba.dubbo.remoting.buffer.ChannelBuffers.wrappedBuffer(
                        input.toByteBuffer());
            }
            //获取channel
            NettyChannel channel = NettyChannel.getOrAddChannel(ctx.getChannel(), url, handler);
            Object msg;
            int saveReaderIndex;

            try {
                // decode object.
                do {
                    saveReaderIndex = message.readerIndex();
                    try {
                        //codec = DubboCountCodec
                        msg = codec.decode(channel, message);
                    } catch (IOException e) {
                        buffer = com.alibaba.dubbo.remoting.buffer.ChannelBuffers.EMPTY_BUFFER;
                        throw e;
                    }
                    //msg = Request [id=5, version=2.0.0, twoway=true, event=false, broken=false, data=RpcInvocation [methodName=queryList, 
//parameterTypes=[], arguments=[], attachments={path=com.bail.user.service.IUserService, input=191, dubbo=2.6.2,
// interface=com.bail.user.service.IUserService, version=1.0.0, timeout=8000}]]
                    if (msg == Codec2.DecodeResult.NEED_MORE_INPUT) {
                        message.readerIndex(saveReaderIndex);
                        break;
                    } else {
                        if (saveReaderIndex == message.readerIndex()) {
                            buffer = com.alibaba.dubbo.remoting.buffer.ChannelBuffers.EMPTY_BUFFER;
                            throw new IOException("Decode without read data.");
                        }
                        if (msg != null) {
                            //触发消息接收动作                            Channels.fireMessageReceived(ctx, msg, event.getRemoteAddress());
                        }
                    }
                } while (message.readable());
            } finally {
                if (message.readable()) {
                    message.discardReadBytes();
                    buffer = message;
                } else {
                    buffer = com.alibaba.dubbo.remoting.buffer.ChannelBuffers.EMPTY_BUFFER;
                }
                NettyChannel.removeChannelIfDisconnected(ctx.getChannel());
            }
        }
    }
}

消息接收

Channels.fireMessageReceived()方法内部调用了ctx.sendUpstream()方法,方法如下

public class Channels {
    public static void fireMessageReceived(
            ChannelHandlerContext ctx, Object message, SocketAddress remoteAddress) {
        //ctx = DefaultChannelHandlerContext
        ctx.sendUpstream(new UpstreamMessageEvent(
                ctx.getChannel(), message, remoteAddress));
    }
}

接着调用DefaultChannelPipeline的sendUpstream方法,往下继续执行,调用的是SimpleChannelHandler的sendUpstream方法

public class DefaultChannelPipeline implements ChannelPipeline {
        public void sendUpstream(ChannelEvent e) {
            DefaultChannelHandlerContext next = getActualUpstreamContext(this.next);
            if (next != null) {
                DefaultChannelPipeline.this.sendUpstream(next, e);
            }
        }
}

SimpleChannelHandler的sendUpstream方法根据不同的事件类型调用不同的处理方法,当接收请求的时候,事件类型为MessageEvent,此处调用messageReceived方法,messageReceived调用具体实现方法

public class SimpleChannelHandler implements ChannelUpstreamHandler, ChannelDownstreamHandler {
    public void handleUpstream(
            ChannelHandlerContext ctx, ChannelEvent e) throws Exception {

        if (e instanceof MessageEvent) {
            messageReceived(ctx, (MessageEvent) e);
        } else if (e instanceof WriteCompletionEvent) {
            WriteCompletionEvent evt = (WriteCompletionEvent) e;
            writeComplete(ctx, evt);
        } else if (e instanceof ChildChannelStateEvent) {
            ChildChannelStateEvent evt = (ChildChannelStateEvent) e;
            if (evt.getChildChannel().isOpen()) {
                childChannelOpen(ctx, evt);
            } else {
                childChannelClosed(ctx, evt);
            }
        } else if (e instanceof ChannelStateEvent) {
            ChannelStateEvent evt = (ChannelStateEvent) e;
            switch (evt.getState()) {
            case OPEN:
                if (Boolean.TRUE.equals(evt.getValue())) {
                    channelOpen(ctx, evt);
                } else {
                    channelClosed(ctx, evt);
                }
                break;
            case BOUND:
                if (evt.getValue() != null) {
                    channelBound(ctx, evt);
                } else {
                    channelUnbound(ctx, evt);
                }
                break;
            case CONNECTED:
                if (evt.getValue() != null) {
                    channelConnected(ctx, evt);
                } else {
                    channelDisconnected(ctx, evt);
                }
                break;
            case INTEREST_OPS:
                channelInterestChanged(ctx, evt);
                break;
            default:
                ctx.sendUpstream(e);
            }
        } else if (e instanceof ExceptionEvent) {
            exceptionCaught(ctx, (ExceptionEvent) e);
        } else {
            ctx.sendUpstream(e);
        }
    }
}

messageReceived

根据消息获取channel信道,调用AbstractPeer的received,实际上调用的是MultiMessageHandler的received方法

public class NettyHandler extends SimpleChannelHandler {

    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        //获取通道
        NettyChannel channel = NettyChannel.getOrAddChannel(ctx.getChannel(), url, handler);
        try {
            handler.received(channel, e.getMessage());
        } finally {
            NettyChannel.removeChannelIfDisconnected(ctx.getChannel());
        }
    }
}

获取channel

获取到NettyChannel ,返回到messageReceived

final class NettyChannel extends AbstractChannel {
    static NettyChannel getOrAddChannel(org.jboss.netty.channel.Channel ch, URL url, ChannelHandler handler) {
        if (ch == null) {
            return null;
        }
        NettyChannel ret = channelMap.get(ch);
        if (ret == null) {
            //handler = nettyServer
            NettyChannel nc = new NettyChannel(ch, url, handler);
            if (ch.isConnected()) {
                ret = channelMap.putIfAbsent(ch, nc);
            }
            if (ret == null) {
                ret = nc;
            }
        }
        //返回一个NettyChannel
        return ret;
    }
}

received

public class MultiMessageHandler extends AbstractChannelHandlerDelegate {

    public MultiMessageHandler(ChannelHandler handler) {
        super(handler);
    }

    @SuppressWarnings("unchecked")
    @Override
    public void received(Channel channel, Object message) throws RemotingException {
        if (message instanceof MultiMessage) {
            MultiMessage list = (MultiMessage) message;
            for (Object obj : list) {
                handler.received(channel, obj);
            }
        } else {
            //此处的handler是一个HeartbeatHandler
            handler.received(channel, message);
        }
    }
}

  • HeartbeatHandler
public class HeartbeatHandler extends AbstractChannelHandlerDelegate {
    public void received(Channel channel, Object message) throws RemotingException {
        setReadTimestamp(channel);
        if (isHeartbeatRequest(message)) {
            Request req = (Request) message;
            if (req.isTwoWay()) {
                Response res = new Response(req.getId(), req.getVersion());
                res.setEvent(Response.HEARTBEAT_EVENT);
                channel.send(res);
                if (logger.isInfoEnabled()) {
                    int heartbeat = channel.getUrl().getParameter(Constants.HEARTBEAT_KEY, 0);
                    if (logger.isDebugEnabled()) {
                        logger.debug("Received heartbeat from remote channel " + channel.getRemoteAddress()
                                + ", cause: The channel has no data-transmission exceeds a heartbeat period"
                                + (heartbeat > 0 ? ": " + heartbeat + "ms" : ""));
                    }
                }
            }
            return;
        }
        if (isHeartbeatResponse(message)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Receive heartbeat response in thread " + Thread.currentThread().getName());
            }
            return;
        }
        //进入最后的方法
        handler.received(channel, message);
    }

}

AllChannelHandler
此处利用多线程,包装了一个多线程任务执行,根据信道、处理器、信道状态、消息包装了一个线程任务,接下里我们分析消息任务

public class AllChannelHandler extends WrappedChannelHandler {
    public void received(Channel channel, Object message) throws RemotingException {
        ExecutorService cexecutor = getExecutorService();
        try {
            //此处利用多线程,包装了一个多线程任务执行
            cexecutor.execute(new ChannelEventRunnable(channel, handler, ChannelState.RECEIVED, message));
        } catch (Throwable t) {
            //TODO A temporary solution to the problem that the exception information can not be sent to the opposite end after the thread pool is full. Need a refactoring
            //fix The thread pool is full, refuses to call, does not return, and causes the consumer to wait for time out
        	if(message instanceof Request && t instanceof RejectedExecutionException){
        		Request request = (Request)message;
        		if(request.isTwoWay()){
        			String msg = "Server side(" + url.getIp() + "," + url.getPort() + ") threadpool is exhausted ,detail msg:" + t.getMessage();
        			Response response = new Response(request.getId(), request.getVersion());
        			response.setStatus(Response.SERVER_THREADPOOL_EXHAUSTED_ERROR);
        			response.setErrorMessage(msg);
        			channel.send(response);
        			return;
        		}
        	}
            throw new ExecutionException(message, channel, getClass() + " error when process received event .", t);
        }
    }
    private ExecutorService getExecutorService() {
        ExecutorService cexecutor = executor;
        if (cexecutor == null || cexecutor.isShutdown()) {
            cexecutor = SHARED_EXECUTOR;
        }
        return cexecutor;
    }
}

消息任务处理

首先我们看一下ChannelEventRunnable,构造函数创建任务以后,执行任务内容run()方法

public class ChannelEventRunnable implements Runnable {
    private final ChannelHandler handler;
    private final Channel channel;
    private final ChannelState state;
    private final Throwable exception;
    private final Object message;
    public ChannelEventRunnable(Channel channel, ChannelHandler handler, ChannelState state, Object message) {
        this(channel, handler, state, message, null);
    }
    public ChannelEventRunnable(Channel channel, ChannelHandler handler, ChannelState state, Object message, Throwable exception) {
        this.channel = channel;
        this.handler = handler;
        this.state = state;
        this.message = message;
        this.exception = exception;
    }

public void run() {
        //此时,state = reveived,调用handler的reveived方法,handler = DecodeHandler
        switch (state) {
            case CONNECTED:
                try {
                    handler.connected(channel);
                } catch (Exception e) {
                    logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel, e);
                }
                break;
            case DISCONNECTED:
                try {
                    handler.disconnected(channel);
                } catch (Exception e) {
                    logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel, e);
                }
                break;
            case SENT:
                try {
                    handler.sent(channel, message);
                } catch (Exception e) {
                    logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel
                            + ", message is " + message, e);
                }
                break;
            case RECEIVED:
                try {
                    handler.received(channel, message);
                } catch (Exception e) {
                    logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel
                            + ", message is " + message, e);
                }
                break;
            case CAUGHT:
                try {
                    handler.caught(channel, exception);
                } catch (Exception e) {
                    logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel
                            + ", message is: " + message + ", exception is " + exception, e);
                }
                break;
            default:
                logger.warn("unknown state: " + state + ", message is " + message);
        }
    }
}

DecodeHandler

调用DecodeHandler的received方法,此时message = Request,从message中获取RpcInvocation,处理之后继续执行handler.received(channel, message)方法,此时handler = HeaderExchangeHandler

  • DecodeHandler
public class DecodeHandler extends AbstractChannelHandlerDelegate {
    public void received(Channel channel, Object message) throws RemotingException {
        if (message instanceof Decodeable) {
            decode(message);
        }

        if (message instanceof Request) {
            decode(((Request) message).getData());
        }

        if (message instanceof Response) {
            decode(((Response) message).getResult());
        }

        handler.received(channel, message);
    }

    private void decode(Object message) {
        if (message != null && message instanceof Decodeable) {
            try {
                //进入解码过程,调用message的decode方法,即RpcInvocation的decode方法,此时调用的是DecodeableRpcInvocation的decode方法。此处更像一个补偿机制,方法内部直接返回。
                ((Decodeable) message).decode();
                if (log.isDebugEnabled()) {
                    log.debug("Decode decodeable message " + message.getClass().getName());
                }
            } catch (Throwable e) {
                if (log.isWarnEnabled()) {
                    log.warn("Call Decodeable.decode failed: " + e.getMessage(), e);
                }
            } // ~ end of catch
        } // ~ end of if
    } 
}
  • DecodeableRpcInvocation
public class DecodeableRpcInvocation extends RpcInvocation implements Codec, Decodeable {
    public void decode() throws Exception {
        if (!hasDecoded && channel != null && inputStream != null) {
            try {
                decode(channel, inputStream);
            } catch (Throwable e) {
                if (log.isWarnEnabled()) {
                    log.warn("Decode rpc invocation failed: " + e.getMessage(), e);
                }
                request.setBroken(true);
                request.setData(e);
            } finally {
                hasDecoded = true;
            }
        }
    }
}

HeaderExchangeHandler

接着调用HeaderExchangeHandler的received方法,强转成request,然后调用handleRequest方法,构造一个Response对象,调用reply方法返回结果,并赋值Response对象。然后通过channel将结果返回。

public class HeaderExchangeHandler implements ChannelHandlerDelegate {
    public void received(Channel channel, Object message) throws RemotingException {
        channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis());
        ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel);
        try {
            if (message instanceof Request) {
                // handle request.
                //强转成request
                Request request = (Request) message;
                if (request.isEvent()) {
                    handlerEvent(channel, request);
                } else {
                    if (request.isTwoWay()) {
                        //调用handleRequest方法
                        Response response = handleRequest(exchangeChannel, request);
                        channel.send(response);
                    } else {
                        handler.received(exchangeChannel, request.getData());
                    }
                }
            } else if (message instanceof Response) {
                handleResponse(channel, (Response) message);
            } else if (message instanceof String) {
                if (isClientSide(channel)) {
                    Exception e = new Exception("Dubbo client can not supported string message: " + message + " in channel: " + channel + ", url: " + channel.getUrl());
                    logger.error(e.getMessage(), e);
                } else {
                    String echo = handler.telnet(channel, (String) message);
                    if (echo != null && echo.length() > 0) {
                        channel.send(echo);
                    }
                }
            } else {
                handler.received(exchangeChannel, message);
            }
        } finally {
            HeaderExchangeChannel.removeChannelIfDisconnected(channel);
        }
    }

    Response handleRequest(ExchangeChannel channel, Request req) throws RemotingException {
        //构造一个Response对象
        Response res = new Response(req.getId(), req.getVersion());
        if (req.isBroken()) {
            Object data = req.getData();

            String msg;
            if (data == null) msg = null;
            else if (data instanceof Throwable) msg = StringUtils.toString((Throwable) data);
            else msg = data.toString();
            res.setErrorMessage("Fail to decode request due to: " + msg);
            res.setStatus(Response.BAD_REQUEST);

            return res;
        }
        // find handler by message class.
        Object msg = req.getData();
        //msg=RpcInvocation
        try {
            // handle data.
            //此时的handler = DubboProtocol的一个内部成员变量 requestHandler
            //调用处理器的reply响应方法
            Object result = handler.reply(channel, msg);
            res.setStatus(Response.OK);
            res.setResult(result);
        } catch (Throwable e) {
            res.setStatus(Response.SERVICE_ERROR);
            res.setErrorMessage(StringUtils.toString(e));
        }
        return res;
    }
}
  • DubboProtocol
    调用reply方法,消息类型为Invocation类型,根据调用信息获取一个调用者,调用的是DubboProtocol类的getInvoker()方法。
    根据serviceKey从暴露缓存容器中获取暴露服务,然后调用暴露服务获取调用者。然后调用调用者的invoke方法。
public class DubboProtocol extends AbstractProtocol {
    private ExchangeHandler requestHandler = new ExchangeHandlerAdapter() {
        public Object reply(ExchangeChannel channel, Object message) throws RemotingException {
            //消息类型为Invocation类型
            if (message instanceof Invocation) {
                Invocation inv = (Invocation) message;
                //根据调用信息获取一个调用者
                Invoker<?> invoker = getInvoker(channel, inv);
                // need to consider backward-compatibility if it's a callback
                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;
                    }
                }
                RpcContext.getContext().setRemoteAddress(channel.getRemoteAddress());
                return invoker.invoke(inv);
            }
            throw new RemotingException(channel, "Unsupported request: "
                    + (message == null ? null : (message.getClass().getName() + ": " + message))
                    + ", channel: consumer: " + channel.getRemoteAddress() + " --> provider: " + channel.getLocalAddress());
        }
  }
    Invoker<?> getInvoker(Channel channel, Invocation inv) throws RemotingException {
        boolean isCallBackServiceInvoke = false;
        boolean isStubServiceInvoke = false;
        //获取本地服务端口为20880,path=com.bail.user.service.IUserService
        int port = channel.getLocalAddress().getPort();
        String path = inv.getAttachments().get(Constants.PATH_KEY);
        // if it's callback service on client side
        //存根服务调用为false
        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());
        }
        //serviceKey = com.bail.user.service.IUserService:1.0.0:20880
        String serviceKey = serviceKey(port, path, inv.getAttachments().get(Constants.VERSION_KEY), inv.getAttachments().get(Constants.GROUP_KEY));
        //然后根据serviceKey从暴露缓存容器中获取暴露服务
        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);
        //exporter = DubboExporter
        return exporter.getInvoker();
    }

}

调用暴露服务Exporter

根据Exporter获取invoker,此时的invoker是一个被ProtocolFilterWrapper包装了的Protocol对象,该对象对invoker进行了Filter包装。返回一个invoker

public abstract class AbstractExporter<T> implements Exporter<T> {
    private final Invoker<T> invoker;
    public Invoker<T> getInvoker() {
        return invoker;
    }
}

调用者执行

从暴露者中获取到调用者之后,开始调用者的执行。首先调用者是ProtocolFilterWrapper类型对象,其中是各个Filter的执行,执行完Filter以后,执行InvokerWrapper的invoke()方法、DelegateProviderMetaDataInvoker的invoke方法,最后是实际Invoker的调用

public class ProtocolFilterWrapper implements Protocol {
    private final Protocol protocol;
    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();
                    }
                    //进行invoke的调用
                    @Override
                    public Result invoke(Invocation invocation) throws RpcException {
                        return filter.invoke(next, invocation);
                    }

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

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

Invoker的invoke

AbstractProxyInvoker调用invoke,接着调用doInvoke,doInvoke最后调用的是动态代理类的doInvoke方法,然后返回结果对象。

public abstract class AbstractProxyInvoker<T> implements Invoker<T> {
    private final T proxy;//proxy = UserServiveImpl@NNNN

    private final Class<T> type; //type = com.bail.user.service.IUserService

    private final URL url;//url = registry://127.0.0.1:2181/com.alibaba.dubbo.registry.RegistryService?application=user-provider&dubbo=2.6.2&export=dubbo://192.168.137.210:20881/com.bail.user.service.IUserService?
//anyhost=true&application=user-provider&bind.ip=192.168.137.210&bind.port=20881&dubbo=2.6.2&generic=false&getUserById.retries=3&getUserBy
Id.timeout=3000
//&interface=com.bail.user.service.IUserService&methods=getUserById,queryList&pid=3120&retries=2&revision=1.0.0
//&side=provider&timeout=8000&timestamp=1638518404364&version=1.0.0&pid=3120&registry=zookeeper&timeout=7200&timestamp=1638518404360
    @Override
    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);
        }
    }
}
  • JavassistProxyFactory
    调用的是在生成代理类调用者的doInvoke方法
public class JavassistProxyFactory extends AbstractProxyFactory {
    @Override
    public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) {
        // TODO Wrapper cannot handle this scenario correctly: the classname contains '$'
        final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);
        return new AbstractProxyInvoker<T>(proxy, type, url) {
            @Override
            protected Object doInvoke(T proxy, String methodName,
                                      Class<?>[] parameterTypes,
                                      Object[] arguments) throws Throwable {
                return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);
            }
        };
    }
}

结果返回

通过channel返回

  • AbstractPeer
public abstract class AbstractPeer implements Endpoint, ChannelHandler {
    @Override
    public void send(Object message) throws RemotingException {
        send(message, url.getParameter(Constants.SENT_KEY, false));
    }
}
  • NettyChannel
    调用父类的send,继续执行channel.write()方法,然后调用的是底层netty的方法,将结果返回
final class NettyChannel extends AbstractChannel {
    public void send(Object message, boolean sent) throws RemotingException {
        super.send(message, sent);

        boolean success = true;
        int timeout = 0;
        try {
            ChannelFuture future = channel.write(message);
            if (sent) {
                timeout = getUrl().getPositiveParameter(Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT);
                success = future.await(timeout);
            }
            Throwable cause = future.getCause();
            if (cause != null) {
                throw cause;
            }
        } catch (Throwable e) {
            throw new RemotingException(this, "Failed to send message " + message + " to " + getRemoteAddress() + ", cause: " + e.getMessage(), e);
        }

        if (!success) {
            throw new RemotingException(this, "Failed to send message " + message + " to " + getRemoteAddress()
                    + "in timeout(" + timeout + "ms) limit");
        }
    }
}
  • AbstractChannel
    对channel状态进行验证,然后返回NettyChannel
public abstract class AbstractChannel extends AbstractPeer implements Channel {
    @Override
    public void send(Object message, boolean sent) throws RemotingException {
        if (isClosed()) {
            throw new RemotingException(this, "Failed to send message "
                    + (message == null ? "" : message.getClass().getName()) + ":" + message
                    + ", cause: Channel closed. channel: " + getLocalAddress() + " -> " + getRemoteAddress());
        }
    }
}
原文地址:https://www.cnblogs.com/nangonghui/p/15637490.html