服务提供者初始化完成之后，对外暴露Exporter。服务消费者初始化完成之后，得到的是Proxy代理，方法调用的时候就是调用代理。
服务消费者经过初始化之后，得到的是一个动态代理类，InvokerInvocationHandler，包含MockClusterInvoker，MockClusterInvoker包含一个RegistryDirectory和FailoverClusterInvoker。
Java动态代理，每一个动态代理类都必须要实现InvocationHandler这个接口，并且每一个代理类的实例都关联到了一个handler，当我们通过代理对象调用一个方法的时候，这个方法就会被转发为由实现了InvocationHandler这个接口的类的invoke方法来进行调用。
服务消费者发起调用请求
InvokerInvocationHandler实现了InvocationHandler接口，当我们调用helloService.sayHello();的时候，实际上会调用invoke()方法：
123456789101112131415161718192021222324252627 |
//proxy是代理的真实对象//method调用真实对象的方法//args调用真实对象的方法的参数public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { //方法名sayHello String methodName = method.getName(); //参数类型 Class<?>[] parameterTypes = method.getParameterTypes(); if (method.getDeclaringClass() == Object.class) { return method.invoke(invoker, args); } if ("toString".equals(methodName) && parameterTypes.length == 0) { return invoker.toString(); } if ("hashCode".equals(methodName) && parameterTypes.length == 0) { return invoker.hashCode(); } if ("equals".equals(methodName) && parameterTypes.length == 1) { return invoker.equals(args[0]); } //invoker是MockClusterInvoker //首先new RpcInvocation //然后invoker.invoke //最后recreate //返回结果 return invoker.invoke(new RpcInvocation(method, args)).recreate();}
|
先看下new RpcInvocation，Invocation是会话域，它持有调用过程中的变量，比如方法名，参数类型等。
接着是invoker.invoke()，这里invoker是MockClusterInvoker，进入MockClusterInvoker.invoker()：
123456789101112131415161718192021222324 |
public Result invoke(Invocation invocation) throws RpcException { Result result = null; //获取mock属性的值，我们没有配置，默认false String value = directory.getUrl().getMethodParameter(invocation.getMethodName(), Constants.MOCK_KEY, Boolean.FALSE.toString()).trim(); if (value.length() == 0 || value.equalsIgnoreCase("false")){ //这里invoker是FailoverClusterInvoker result = this.invoker.invoke(invocation); } else if (value.startsWith("force")) { //force:direct mock result = doMockInvoke(invocation, null); } else { //fail-mock try { result = this.invoker.invoke(invocation); }catch (RpcException e) { if (e.isBiz()) { throw e; } else { result = doMockInvoke(invocation, e); } } } return result;}
|
result = this.invoker.invoke(invocation);这里invoker是FailoverClusterInvoker，会首先进入AbstractClusterInvoker的invoke方法：
12345678910111213141516171819 |
public Result invoke(final Invocation invocation) throws RpcException { //检查是否被销毁 checkWheatherDestoried(); LoadBalance loadbalance; //根据invocation中的参数来获取所有的invoker列表 List<Invoker<T>> invokers = list(invocation); if (invokers != null && invokers.size() > 0) { //我们没有配置负载均衡的参数，默认使用random //这里得到的是RandomLoadBalance loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl() .getMethodParameter(invocation.getMethodName(),Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE)); } else { loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE); } //如果是异步操作默认添加invocation id RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation); //这里是子类实现，FailoverClusterInvoker中，执行调用 return doInvoke(invocation, invokers, loadbalance);}
|
FailoverClusterInvoker.doInvoke()：
1234567891011121314151617181920212223242526272829303132333435363738 |
public Result doInvoke(Invocation invocation, final List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException { List<Invoker<T>> copyinvokers = invokers; //检查invokers是否为空 checkInvokers(copyinvokers, invocation); //重试次数 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. //已经调用过的invoker 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); } //使用负载均衡选择invoker.（负载均衡咱先不做解释） Invoker<T> invoker = select(loadbalance, invocation, copyinvokers, invoked); invoked.add(invoker); //添加到以调用过的列表中 RpcContext.getContext().setInvokers((List)invoked); try { //开始调用，返回结果 Result result = invoker.invoke(invocation); return result; } catch (RpcException e) {。。。 } finally { providers.add(invoker.getUrl().getAddress()); } } throw new RpcException(。。。);}
|
Result result = invoker.invoke(invocation);调用并返回结果，会首先进入InvokerWrapper，然后进入ListenerInvokerWrapper的invoke方法，接着进入AbstractInvoker的invoke：
123456789101112131415161718192021222324 |
public Result invoke(Invocation inv) throws RpcException { if(destroyed) { throw new RpcException(。。。); } //转成RpcInvocation RpcInvocation invocation = (RpcInvocation) inv; invocation.setInvoker(this); if (attachment != null && attachment.size() > 0) { invocation.addAttachmentsIfAbsent(attachment); } Map<String, String> context = RpcContext.getContext().getAttachments(); if (context != null) { invocation.addAttachmentsIfAbsent(context); } if (getUrl().getMethodParameter(invocation.getMethodName(), Constants.ASYNC_KEY, false)){ invocation.setAttachment(Constants.ASYNC_KEY, Boolean.TRUE.toString()); } //异步的话，需要添加id RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation); try { //这里是DubboInvoker return doInvoke(invocation); } catch (InvocationTargetException e) { } }
|
DubboInvoker.doInvoke()：
123456789101112131415161718192021222324252627282930313233343536 |
protected Result doInvoke(final Invocation invocation) throws Throwable { RpcInvocation inv = (RpcInvocation) invocation; final String methodName = RpcUtils.getMethodName(invocation); inv.setAttachment(Constants.PATH_KEY, getUrl().getPath()); inv.setAttachment(Constants.VERSION_KEY, version);
ExchangeClient currentClient; //在初始化的时候，引用服务的过程中会保存一个连接到服务端的Client if (clients.length == 1) { currentClient = clients[0]; } else { currentClient = clients[index.getAndIncrement() % clients.length]; } try { //异步标志 boolean isAsync = RpcUtils.isAsync(getUrl(), invocation); //单向标志 boolean isOneway = RpcUtils.isOneway(getUrl(), invocation); int timeout = getUrl().getMethodParameter(methodName, Constants.TIMEOUT_KEY,Constants.DEFAULT_TIMEOUT); //单向的，反送完不管结果 if (isOneway) { boolean isSent = getUrl().getMethodParameter(methodName, Constants.SENT_KEY, false); currentClient.send(inv, isSent); RpcContext.getContext().setFuture(null); return new RpcResult(); } else if (isAsync) {//异步的，发送完需要得到Future ResponseFuture future = currentClient.request(inv, timeout) ; RpcContext.getContext().setFuture(new FutureAdapter<Object>(future)); return new RpcResult(); } else {//同步调用，我们这里使用的这种方式 RpcContext.getContext().setFuture(null); //HeaderExchangeClient return (Result) currentClient.request(inv, timeout).get(); } } catch (TimeoutException e) {。。。}}
|
我们这里使用的是同步调用，看(Result) currentClient.request(inv, timeout).get();方法，这里的client是ReferenceCountExchangeClient，直接调用HeaderExchangeClient的request方法：
1234 |
public ResponseFuture request(Object request, int timeout) throws RemotingException { //这里的Channel是HeaderExchangeChannel return channel.request(request, timeout);}
|
进入HeaderExchangeChannel的request方法：
1234567891011121314151617181920212223242526 |
public ResponseFuture request(Object request, int timeout) throws RemotingException { if (closed) { throw new RemotingException(。。。); } //创建一个请求头 Request req = new Request(); req.setVersion("2.0.0"); req.setTwoWay(true); //这里request参数里面保存着 //methodName = "sayHello" //parameterTypes = {Class[0]@2814} //arguments = {Object[0]@2768} //attachments = {[email protected]} size = 4 //invoker = {[email protected]} req.setData(request); DefaultFuture future = new DefaultFuture(channel, req, timeout); try{ //这里的channel是NettyClient //发送请求 channel.send(req); }catch (RemotingException e) { future.cancel(); throw e; } return future;}
|
channel.send(req)，首先会调用AbstractPeer的send方法：
1234 |
//子类处理，接着是AbstractClient执行发送public void send(Object message) throws RemotingException { send(message, url.getParameter(Constants.SENT_KEY, false));}
|
AbstractClient执行发送：
1234567891011121314 |
public void send(Object message, boolean sent) throws RemotingException { //重连 if (send_reconnect && !isConnected()){ connect(); } //先获取Channel，是在NettyClient中实现的 Channel channel = getChannel(); //TODO getChannel返回的状态是否包含null需要改进 if (channel == null || ! channel.isConnected()) { throw new RemotingException(this, "message can not send, because channel is closed . url:" + getUrl()); } channel是NettyChannel channel.send(message, sent);}
|
channel.send(message, sent);首先经过AbstractChannel的send方法处理，只是判断是否关闭了，然后是NettyChannel的send来继续处理，这里就把消息发送到服务端了：
12345678910111213141516171819202122232425 |
public void send(Object message, boolean sent) throws RemotingException { super.send(message, sent);
boolean success = true; int timeout = 0; try { //交给netty处理 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"); }}
|
服务提供者处理并响应请求
服务端已经打开端口并监听请求的到来，当服务消费者发送调用请求的时候，经过Netty的处理后会到dubbo中的codec相关方法中先进行解码，入口是NettyCodecAdapter.messageReceived()，关于这个方法的代码在dubbo编解码的那篇文章中已经分析过，不再重复。经过解码之后，会进入到NettyHandler.messageReceived()方法：
12345678910 |
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { //获取channel NettyChannel channel = NettyChannel.getOrAddChannel(ctx.getChannel(), url, handler); try { //这里handler是NettyServer handler.received(channel, e.getMessage()); } finally { NettyChannel.removeChannelIfDisconnected(ctx.getChannel()); }}
|
接着会进入AbstractPeer的received方法：
1234567 |
public void received(Channel ch, Object msg) throws RemotingException { if (closed) { return; } //这里是MultiMessageHandler handler.received(ch, msg);}
|
进入MultiMessageHandler的received方法：
123456789101112 |
public void received(Channel channel, Object message) throws RemotingException { //是多消息的话，使用多消息处理器处理 if (message instanceof MultiMessage) { MultiMessage list = (MultiMessage)message; for(Object obj : list) { handler.received(channel, obj); } } else { //这里是HeartbeatHandler handler.received(channel, message); }}
|
进入HeartbeatHandler的received方法：
12345678910111213141516171819 |
public void received(Channel channel, Object message) throws RemotingException { setReadTimestamp(channel); //心跳请求处理 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); } return; } //心跳回应消息处理 if (isHeartbeatResponse(message)) { return; } //这里是AllChannelHandler handler.received(channel, message);}
|
继续进入AllChannelHandler的received方法：
12345678 |
public void received(Channel channel, Object message) throws RemotingException { //获取线程池执行 ExecutorService cexecutor = getExecutorService(); try { //handler是DecodeHandler cexecutor.execute(new ChannelEventRunnable(channel, handler, ChannelState.RECEIVED, message)); } catch (Throwable t) { }}
|
这里会去启动新线程执行ChannelEventRunnable的run方法，接着去调用DecodeHandler的received方法：
12345678910111213141516 |
public void received(Channel channel, Object message) throws RemotingException { //不清楚啥意思 if (message instanceof Decodeable) { decode(message); } //解码请求类型 if (message instanceof Request) { decode(((Request)message).getData()); } //解码响应类型 if (message instanceof Response) { decode( ((Response)message).getResult()); } //解码之后到HeaderExchangeHandler中处理 handler.received(channel, message);}
|
解码之后到HeaderExchangeHandler的received方法：
123456789101112131415161718192021222324252627282930313233343536373839 |
public void received(Channel channel, Object message) throws RemotingException { channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis()); ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel); try { //request类型的消息 if (message instanceof Request) { Request request = (Request) message; if (request.isEvent()) {//判断心跳还是正常请求 // 处理心跳 handlerEvent(channel, request); } else {//正常的请求 //需要返回 if (request.isTwoWay()) { //处理请求，并构造响应信息 Response response = handleRequest(exchangeChannel, request); //NettyChannel，发送响应信息 channel.send(response); } else {//不需要返回的处理 handler.received(exchangeChannel, request.getData()); } } } else if (message instanceof Response) {//response类型的消息 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()); } else {//telnet类型 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); }}
|
先看下处理请求，并构造响应信息：
123456789101112131415161718192021222324 |
Response handleRequest(ExchangeChannel channel, Request req) throws RemotingException { 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(); try { //处理请求数据，handler是DubboProtocol中的new的一个ExchangeHandlerAdapter Object result = handler.reply(channel, msg); res.setStatus(Response.OK); res.setResult(result); } catch (Throwable e) { } return res;}
|
进入DubboProtocol中的ExchangeHandlerAdapter的replay方法：
12345678910111213141516171819202122232425262728293031 |
public Object reply(ExchangeChannel channel, Object message) throws RemotingException { if (message instanceof Invocation) { //Invocation中保存着方法名等 Invocation inv = (Invocation) message; //获取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){ return null; } } RpcContext.getContext().setRemoteAddress(channel.getRemoteAddress()); //执行调用，然后返回结果 return invoker.invoke(inv); } throw new RemotingException(。。。); }
|
先看下getInvoker获取Invoker：
1234567891011121314151617181920212223242526 |
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)); //从之前缓存的exporterMap中查找Exporter //key：dubbo.common.hello.service.HelloService:20880 DubboExporter<?> exporter = (DubboExporter<?>) exporterMap.get(serviceKey);
if (exporter == null) throw new RemotingException(。。。）; //得到Invoker，返回 return exporter.getInvoker();}
|
再看执行调用invoker.invoke(inv);，会先进入InvokerWrapper：
123 |
public Result invoke(Invocation invocation) throws RpcException { return invoker.invoke(invocation);}
|
接着进入AbstractProxyInvoker：
1234567 |
public Result invoke(Invocation invocation) throws RpcException { try { //先doInvoke //然后封装成结果返回 return new RpcResult(doInvoke(proxy, invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments())); } catch (InvocationTargetException e) {。。。}}
|
这里的doInvoke是在JavassistProxyFactory中的AbstractProxyInvoker实例：
12345678910111213 |
public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) { // TODO Wrapper类不能正确处理带$的类名 final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf(‘$‘) < 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 { //这里就调用了具体的方法 return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments); } };}
|
消息处理完后返回到HeaderExchangeHandler的received方法：
123456789101112131415161718192021222324252627282930313233343536373839 |
public void received(Channel channel, Object message) throws RemotingException { channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis()); ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel); try { //request类型的消息 if (message instanceof Request) { Request request = (Request) message; if (request.isEvent()) {//判断心跳还是正常请求 // 处理心跳 handlerEvent(channel, request); } else {//正常的请求 //需要返回 if (request.isTwoWay()) { //处理请求，并构造响应信息，这在上面已经解析过了 Response response = handleRequest(exchangeChannel, request); //NettyChannel，发送响应信息 channel.send(response); } else {//不需要返回的处理 handler.received(exchangeChannel, request.getData()); } } } else if (message instanceof Response) {//response类型的消息 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()); } else {//telnet类型 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); }}
|
解析完请求，构造完响应消息，就开始发送响应了,channel.send(response);，先经过AbstractPeer:
1234 |
public void send(Object message) throws RemotingException { //NettyChannel send(message, url.getParameter(Constants.SENT_KEY, false));}
|
进入NettyChannel中，进行响应消息的发送：
12345678910111213141516171819202122232425 |
public void send(Object message, boolean sent) throws RemotingException { //AbstractChannel的处理 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"); }}
|
消费者接受到服务端返回的响应后的处理
服务提供者端接收到消费者端的请求并处理之后，返回给消费者端，消费者这边接受响应的入口跟提供者差不多，也是NettyCodecAdapter.messageReceived()，经过解码，到NettyHandler.messageReceived()处理：
123456789 |
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { NettyChannel channel = NettyChannel.getOrAddChannel(ctx.getChannel(), url, handler); try { //NettyClient handler.received(channel, e.getMessage()); } finally { NettyChannel.removeChannelIfDisconnected(ctx.getChannel()); }}
|
先经过AbstractPeer的received方法：
1234567 |
public void received(Channel ch, Object msg) throws RemotingException { if (closed) { return; } //MultiMessageHandler handler.received(ch, msg);}
|
进入MultiMessageHandler：
1234567891011 |
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 { //HeartbeatHandler handler.received(channel, message); }}
|
进入HeartbeatHandler，根据不同类型进行处理：
1234567891011121314151617181920212223242526272829303132 |
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( new StringBuilder(32) .append("Receive heartbeat response in thread ") .append(Thread.currentThread().getName()) .toString()); } return; } //AllChannelHandler handler.received(channel, message);}
|
进入AllChannelHandler：
12345678 |
public void received(Channel channel, Object message) throws RemotingException { ExecutorService cexecutor = getExecutorService(); try { cexecutor.execute(new ChannelEventRunnable(channel, handler, ChannelState.RECEIVED, message)); } catch (Throwable t) { throw new ExecutionException(message, channel, getClass() + " error when process received event .", t); }}
|
然后在新线程，ChannelEventRunnable的run方法中进入DecodeHandler：
123456789101112131415 |
public void received(Channel channel, Object message) throws RemotingException { if (message instanceof Decodeable) { decode(message); }
if (message instanceof Request) { decode(((Request)message).getData()); } //这里进行response类型的处理 if (message instanceof Response) { decode( ((Response)message).getResult()); }
handler.received(channel, message);}
|
进入处理response的decode方法，进行解码response：
1234567 |
private void decode(Object message) { if (message != null && message instanceof Decodeable) { try { ((Decodeable)message).decode(); } catch (Throwable e) {。。。} // ~ end of catch } // ~ end of if}
|
接着会进入HeaderExchangerHandler.received () 方法：
123456789101112131415161718192021222324252627282930313233 |
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) { Request request = (Request) message; if (request.isEvent()) { handlerEvent(channel, request); } else { if (request.isTwoWay()) { Response response = handleRequest(exchangeChannel, request); channel.send(response); } else { handler.received(exchangeChannel, request.getData()); } } } else if (message instanceof Response) { //这里处理response消息 handleResponse(channel, (Response) message); } else if (message instanceof String) { if (isClientSide(channel)) { Exception } 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); }}
|
handleResponse方法：
12345 |
static void handleResponse(Channel channel, Response response) throws RemotingException { if (response != null && !response.isHeartbeat()) { DefaultFuture.received(channel, response); }}
|
这一步设置response到消费者请求的Future中，以供消费者通过DefaultFuture.get()取得提供者的响应，此为同步转异步重要一步，且请求超时也由DefaultFuture控制。
然后就是return (Result) currentClient.request(inv, timeout).get();在DubboInvoker中，这里继续执行，然后执行Filter，最后返回到InvokerInvocationHandler.invoker()方法中，方法得到调用结果，结束！
注意：
消费者端的DubboInvoker发起请求后，后续的逻辑是异步的或是指定超时时间内阻塞的，直到得到响应结果后，继续执行DubboInvoker中逻辑。
对于异步请求时，消费者得到Future，其余逻辑均是异步的。
消费者还可以通过设置async、sent、return来调整处理逻辑，async指异步还是同步请求，sent指是否等待请求消息发出即阻塞等待是否成功发出请求、return指是否忽略返回值即但方向通信，一般异步时使用以减少Future对象的创建和管理成本。
时间： 2024-10-28 10:09:16