远程调用
InvokerInvocationHandler.java
public InvokerInvocationHandler(Invoker<?> handler) {
this.invoker = handler;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// 获取到RPC远程调用的方法名
String methodName = method.getName();
Class<?>[] parameterTypes = method.getParameterTypes();
// 若当前方法为Object的方法，则为本地方法调用
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]);
}
// 远程调用。此处创建出来的是MockClusterInvoker。
// 而MockClusterInvoker是在上次源代码分析中ReferenceConfig.java中createProxy()创建代理对象中
// invoker = CLUSTER.join(new StaticDirectory(u, invokers));这行代码创建出来的
return invoker.invoke(new RpcInvocation(method, args)).recreate();
}
MockClusterInvoker.java
public Result invoke(Invocation invocation) throws RpcException {
Result result = null;
// 获取mock属性值
String value = directory.getUrl().getMethodParameter(invocation.getMethodName(), MOCK_KEY, Boolean.FALSE.toString()).trim();
// 若没有设置mock属性，或mock属性值为false，则不具有降级功能
if (value.length() == 0 || value.equalsIgnoreCase("false")) {
//no mock 远程调用(不会降级)
result = this.invoker.invoke(invocation);
} else if (value.startsWith("force")) {
if (logger.isWarnEnabled()) {
logger.warn("force-mock: " + invocation.getMethodName() + " force-mock enabled , url : " + directory.getUrl());
}
//force:direct mock 直接降级
result = doMockInvoke(invocation, null);
} else {
//fail-mock
try { // 远程调用
result = this.invoker.invoke(invocation);
} catch (RpcException e) {
if (e.isBiz()) {
throw e;
}
if (logger.isWarnEnabled()) {
logger.warn("fail-mock: " + invocation.getMethodName() + " fail-mock enabled , url : " + directory.getUrl(), e);
}
// 服务降级
result = doMockInvoke(invocation, e);
}
}
return result;
}
AbstractClusterInvoker.java
public Result invoke(final Invocation invocation) throws RpcException {
checkWhetherDestroyed();
// binding attachments into invocation.
Map<String, String> contextAttachments = RpcContext.getContext().getAttachments();
if (contextAttachments != null && contextAttachments.size() != 0) {
((RpcInvocation) invocation).addAttachments(contextAttachments);
}
// 路由：根据路由规则过滤掉不可用的invoker，返回剩下的可用的invoker
List<Invoker<T>> invokers = list(invocation);
// 获取负载均衡策略
LoadBalance loadbalance = initLoadBalance(invokers, invocation);
RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
// 调用具体容错策略的doInvoke()
return doInvoke(invocation, invokers, loadbalance);
}
FailoverClusterInvoker.java
public Result doInvoke(Invocation invocation, final List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {
List<Invoker<T>> copyInvokers = invokers;
checkInvokers(copyInvokers, invocation);
String methodName = RpcUtils.getMethodName(invocation);
int len = getUrl().getMethodParameter(methodName, RETRIES_KEY, DEFAULT_RETRIES) + 1;
if (len <= 0) {
len = 1;
}
// retry loop.
RpcException le = null; // last exception.
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++) {
//Reselect before retry to avoid a change of candidate `invokers`.
//NOTE: if `invokers` changed, then `invoked` also lose accuracy.
if (i > 0) {
checkWhetherDestroyed();
copyInvokers = list(invocation);
// check again
checkInvokers(copyInvokers, invocation);
} // 负载均衡
Invoker<T> invoker = select(loadbalance, invocation, copyInvokers, invoked);
invoked.add(invoker);
RpcContext.getContext().setInvokers((List) invoked);
try { // 远程调用
Result result = invoker.invoke(invocation);
if (le != null && logger.isWarnEnabled()) {
logger.warn("Although retry the method " + methodName
+ " in the service " + getInterface().getName()
+ " was successful by the provider " + invoker.getUrl().getAddress()
+ ", but there have been failed providers " + providers
+ " (" + providers.size() + "/" + copyInvokers.size()
+ ") from the registry " + directory.getUrl().getAddress()
+ " on the consumer " + NetUtils.getLocalHost()
+ " using the dubbo version " + Version.getVersion() + ". Last error is: "
+ le.getMessage(), le);
}
return result;
} catch (RpcException e) {
if (e.isBiz()) { // biz exception.
throw e;
}
le = e;
} catch (Throwable e) {
le = new RpcException(e.getMessage(), e);
} finally {
providers.add(invoker.getUrl().getAddress());
}
}
throw new RpcException(le.getCode(), "Failed to invoke the method "
+ methodName + " in the service " + getInterface().getName()
+ ". Tried " + len + " times of the providers " + providers
+ " (" + providers.size() + "/" + copyInvokers.size()
+ ") from the registry " + directory.getUrl().getAddress()
+ " on the consumer " + NetUtils.getLocalHost() + " using the dubbo version "
+ Version.getVersion() + ". Last error is: "
+ le.getMessage(), le.getCause() != null ? le.getCause() : le);
}
ProtocolFilterWrapper.java
public Result invoke(Invocation invocation) throws RpcException {
Result asyncResult = filterInvoker.invoke(invocation); // 返回一个异步结果
asyncResult = asyncResult.whenCompleteWithContext((r, t) -> {
for (int i = filters.size() - 1; i >= 0; i--) {
Filter filter = filters.get(i);
// onResponse callback
if (filter instanceof ListenableFilter) {
Filter.Listener listener = ((ListenableFilter) filter).listener();
if (listener != null) {
if (t == null) {
listener.onResponse(r, filterInvoker, invocation);
} else {
listener.onError(t, filterInvoker, invocation);
}
}
} else {
filter.onResponse(r, filterInvoker, invocation);
}
}
});
return asyncResult;
}
public Result invoke(Invocation invocation) throws RpcException {
Result asyncResult;
try {
// 继续追这里
asyncResult = filter.invoke(next, invocation);
} catch (Exception e) {
// onError callback
if (filter instanceof ListenableFilter) {
Filter.Listener listener = ((ListenableFilter) filter).listener();
if (listener != null) {
listener.onError(e, invoker, invocation);
}
}
throw e;
}
return asyncResult;
}
MonitorFilter.java
public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
if (invoker.getUrl().hasParameter(MONITOR_KEY)) {
invocation.setAttachment(MONITOR_FILTER_START_TIME, String.valueOf(System.currentTimeMillis()));
getConcurrent(invoker, invocation).incrementAndGet(); // count up
}
return invoker.invoke(invocation); // proceed invocation chain
}
ListenerInvokerWrapper.java
public Result invoke(Invocation invocation) throws RpcException {
return invoker.invoke(invocation);
}
AsyncToSyncInvoker.java
public Result invoke(Invocation invocation) throws RpcException {
Result asyncResult = invoker.invoke(invocation);
try {
if (InvokeMode.SYNC == ((RpcInvocation) invocation).getInvokeMode()) {
asyncResult.get(Integer.MAX_VALUE, TimeUnit.MILLISECONDS);
}
} catch (InterruptedException e) {
throw new RpcException("Interrupted unexpectedly while waiting for remoting result to return! method: " + invocation.getMethodName() + ", provider: " + getUrl() + ", cause: " + e.getMessage(), e);
} catch (ExecutionException e) {
Throwable t = e.getCause();
if (t instanceof TimeoutException) {
throw new RpcException(RpcException.TIMEOUT_EXCEPTION, "Invoke remote method timeout. method: " + invocation.getMethodName() + ", provider: " + getUrl() + ", cause: " + e.getMessage(), e);
} else if (t instanceof RemotingException) {
throw new RpcException(RpcException.NETWORK_EXCEPTION, "Failed to invoke remote method: " + invocation.getMethodName() + ", provider: " + getUrl() + ", cause: " + e.getMessage(), e);
}
} catch (Throwable e) {
throw new RpcException(e.getMessage(), e);
}
return asyncResult;
}
AbstractInvoker.java
public Result invoke(Invocation inv) throws RpcException {
// if invoker is destroyed due to address refresh from registry, let's allow the current invoke to proceed
if (destroyed.get()) {
logger.warn("Invoker for service " + this + " on consumer " + NetUtils.getLocalHost() + " is destroyed, "
+ ", dubbo version is " + Version.getVersion() + ", this invoker should not be used any longer");
}
RpcInvocation invocation = (RpcInvocation) inv;
invocation.setInvoker(this);
if (CollectionUtils.isNotEmptyMap(attachment)) {
invocation.addAttachmentsIfAbsent(attachment);
}
Map<String, String> contextAttachments = RpcContext.getContext().getAttachments();
if (CollectionUtils.isNotEmptyMap(contextAttachments)) {
/**
* invocation.addAttachmentsIfAbsent(context){@link RpcInvocation#addAttachmentsIfAbsent(Map)}should not be used here,
* because the {@link RpcContext#setAttachment(String, String)} is passed in the Filter when the call is triggered
* by the built-in retry mechanism of the Dubbo. The attachment to update RpcContext will no longer work, which is
* a mistake in most cases (for example, through Filter to RpcContext output traceId and spanId and other information).
*/
invocation.addAttachments(contextAttachments);
}
invocation.setInvokeMode(RpcUtils.getInvokeMode(url, invocation));
RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
try {
//跟这里
return doInvoke(invocation); //
} catch (InvocationTargetException e) { // biz exception
Throwable te = e.getTargetException();
if (te == null) {
return AsyncRpcResult.newDefaultAsyncResult(null, e, invocation);
} else {
if (te instanceof RpcException) {
((RpcException) te).setCode(RpcException.BIZ_EXCEPTION);
}
return AsyncRpcResult.newDefaultAsyncResult(null, te, invocation);
}
} catch (RpcException e) {
if (e.isBiz()) {
return AsyncRpcResult.newDefaultAsyncResult(null, e, invocation);
} else {
throw e;
}
} catch (Throwable e) {
return AsyncRpcResult.newDefaultAsyncResult(null, e, invocation);
}
}
DubboInvoker.java
protected Result doInvoke(final Invocation invocation) throws Throwable {
RpcInvocation inv = (RpcInvocation) invocation;
final String methodName = RpcUtils.getMethodName(invocation);
inv.setAttachment(PATH_KEY, getUrl().getPath());
inv.setAttachment(VERSION_KEY, version);
ExchangeClient currentClient;
// clients是一个ExchangeClient数组，若只有一个ExchangeClient，则直接返回，否则通过轮询方式返回一个
if (clients.length == 1) {
currentClient = clients[0];
} else { // 轮询返回一个exchangeClient
currentClient = clients[index.getAndIncrement() % clients.length];
}
try { // 若一个请求无需响应，则isOneway为true，表示单向的
boolean isOneway = RpcUtils.isOneway(getUrl(), invocation);
int timeout = getUrl().getMethodPositiveParameter(methodName, TIMEOUT_KEY, DEFAULT_TIMEOUT);
if (isOneway) {
boolean isSent = getUrl().getMethodParameter(methodName, Constants.SENT_KEY, false);
currentClient.send(inv, isSent);
return AsyncRpcResult.newDefaultAsyncResult(invocation);
} else {
AsyncRpcResult asyncRpcResult = new AsyncRpcResult(inv);
// 通过同异步转换对象currentClient发送请求
CompletableFuture<Object> responseFuture = currentClient.request(inv, timeout);
asyncRpcResult.subscribeTo(responseFuture);
// save for 2.6.x compatibility, for example, TraceFilter in Zipkin uses com.alibaba.xxx.FutureAdapter
FutureContext.getContext().setCompatibleFuture(responseFuture);
return asyncRpcResult;
}
} catch (TimeoutException e) {
throw new RpcException(RpcException.TIMEOUT_EXCEPTION, "Invoke remote method timeout. method: " + invocation.getMethodName() + ", provider: " + getUrl() + ", cause: " + e.getMessage(), e);
} catch (RemotingException e) {
throw new RpcException(RpcException.NETWORK_EXCEPTION, "Failed to invoke remote method: " + invocation.getMethodName() + ", provider: " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
ReferenceCountExchangeClient.java
public CompletableFuture<Object> request(Object request, int timeout) throws RemotingException {
return client.request(request, timeout);
}
HeaderExchangeClient.java
public CompletableFuture<Object> request(Object request, int timeout) throws RemotingException {
return channel.request(request, timeout);
}
HeaderExchangeChannel.java
public CompletableFuture<Object> 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(Version.getProtocolVersion());
req.setTwoWay(true);
req.setData(request);
DefaultFuture future = DefaultFuture.newFuture(channel, req, timeout);
try {
channel.send(req); // 发送请求
} catch (RemotingException e) {
future.cancel();
throw e;
}
return future;
}
AbstractPeer.java
public void send(Object message) throws RemotingException {
send(message, url.getParameter(Constants.SENT_KEY, false));
}
AbstractClient.java
public void send(Object message, boolean sent) throws RemotingException {
if (needReconnect && !isConnected()) {
connect(); // 连接Server
}
Channel channel = getChannel();
//TODO Can the value returned by getChannel() be null? need improvement.
if (channel == null || !channel.isConnected()) {
throw new RemotingException(this, "message can not send, because channel is closed . url:" + getUrl());
}
channel.send(message, sent); // 发送请求
}
NettyChannel.java
public void send(Object message, boolean sent) throws RemotingException {
// whether the channel is closed
super.send(message, sent);
boolean success = true;
int timeout = 0;
try {
ChannelFuture future = channel.writeAndFlush(message); // 向Server发送数据
if (sent) {
// wait timeout ms
timeout = getUrl().getPositiveParameter(TIMEOUT_KEY, DEFAULT_TIMEOUT);
success = future.await(timeout);
}
Throwable cause = future.cause();
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");
}
}
提供者处理消费者请求
NettyServer.java
protected void doOpen() throws Throwable {
bootstrap = new ServerBootstrap();
// 处理连接的Group
bossGroup = new NioEventLoopGroup(1, new DefaultThreadFactory("NettyServerBoss", true));
// 处理IO业务的Group
workerGroup = new NioEventLoopGroup(getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS),
new DefaultThreadFactory("NettyServerWorker", true));
//提供者的URL
final NettyServerHandler nettyServerHandler = new NettyServerHandler(getUrl(), this);
channels = nettyServerHandler.getChannels();
bootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE)
.childOption(ChannelOption.SO_REUSEADDR, Boolean.TRUE)
.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
.childHandler(new ChannelInitializer<NioSocketChannel>() {
@Override
protected void initChannel(NioSocketChannel ch) throws Exception {
// FIXME: should we use getTimeout()?
int idleTimeout = UrlUtils.getIdleTimeout(getUrl());
NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);
ch.pipeline()//.addLast("logging",new LoggingHandler(LogLevel.INFO))//for debug
// 解码器
.addLast("decoder", adapter.getDecoder())
// 编码器
.addLast("encoder", adapter.getEncoder())
// 读写空闲监测
.addLast("server-idle-handler", new IdleStateHandler(0, 0, idleTimeout, MILLISECONDS))
// Dubbo的自定义处理器
.addLast("handler", nettyServerHandler);
}
});
// bind
ChannelFuture channelFuture = bootstrap.bind(getBindAddress());
channelFuture.syncUninterruptibly();
channel = channelFuture.channel();
}
NettyServerHandler.java
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
NettyChannel channel = NettyChannel.getOrAddChannel(ctx.channel(), url, handler);
try {
// 这块再跟下去就是Netty底层了。
handler.received(channel, msg);
} finally {
NettyChannel.removeChannelIfDisconnected(ctx.channel());
}
}
AllChannelHandler.java
public void received(Channel channel, Object message) throws RemotingException {
ExecutorService executor = getExecutorService(); // 线程池
try { // 将Client发送来处数据包装为一个任务，使用线程池中的线程来完成
executor.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);
}
}
ChannelEventRunnable.java
public void run() {
// 接收到处理任务
if (state == ChannelState.RECEIVED) {
try {
handler.received(channel, message);
} catch (Exception e) {
logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel
+ ", message is " + message, e);
}
}
......
}
DecodeHandler.java
// 接下来对数据进行解码,然后对数据进行解析然后处理消费者的请求
public void received(Channel channel, Object message) throws RemotingException {
if (message instanceof Decodeable) {
decode(message); // 解码消息
}
if (message instanceof Request) {
decode(((Request) message).getData()); // 解码RpcInvocation
}
if (message instanceof Response) {
decode(((Response) message).getResult()); // 解码响应结果
}
// 此时的message是经过解码的
handler.received(channel, message);
}
HeaderExchangeHandler.java
public void received(Channel channel, Object message) throws RemotingException {
channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis());
final ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel);
try {
if (message instanceof Request) { // 处理message为请求的情况
// handle request.
Request request = (Request) message;
if (request.isEvent()) {
handlerEvent(channel, request);
} else {
if (request.isTwoWay()) {
handleRequest(exchangeChannel, request); // 处理请求
} else {
handler.received(exchangeChannel, request.getData());
}
}
} else if (message instanceof Response) { // 处理message为响应的情况
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);
}
}
void handleRequest(final ExchangeChannel channel, Request req) throws RemotingException {
Response res = new Response(req.getId(), req.getVersion());
if (req.isBroken()) { // 若请求过程中发生了异常，则在这里处理
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);
channel.send(res); // 将包含有异常信息的响应返回
return;
}
// find handler by message class.
Object msg = req.getData(); // 获取RpcInvocation
try {
CompletionStage<Object> future = handler.reply(channel, msg);
future.whenComplete((appResult, t) -> {
try {
if (t == null) {
res.setStatus(Response.OK);
res.setResult(appResult);
} else {
res.setStatus(Response.SERVICE_ERROR);
res.setErrorMessage(StringUtils.toString(t));
}
channel.send(res); // 将真正的响应结果返回
} catch (RemotingException e) {
logger.warn("Send result to consumer failed, channel is " + channel + ", msg is " + e);
} finally {
// HeaderExchangeChannel.removeChannelIfDisconnected(channel);
}
});
} catch (Throwable e) {
res.setStatus(Response.SERVICE_ERROR);
res.setErrorMessage(StringUtils.toString(e));
channel.send(res);
}
}
DubboProtocol.java
@Override
public CompletableFuture<Object> reply(ExchangeChannel channel, Object message) throws RemotingException {
if (!(message instanceof Invocation)) {
throw new RemotingException(channel, "Unsupported request: "
+ (message == null ? null : (message.getClass().getName() + ": " + message))
+ ", channel: consumer: " + channel.getRemoteAddress() + " --> provider: " + channel.getLocalAddress());
}
Invocation inv = (Invocation) message;
Invoker<?> invoker = getInvoker(channel, inv); // 获取到invoker
// 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.contains(",")) {
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());
Result result = invoker.invoke(inv); // 进行本地调用并获得一个Result结果
return result.completionFuture().thenApply(Function.identity());
}
消费者处理提供者响应
NettyClientHandler.java
// 消费者收到提供者的响应,首先会创建一个NettyClinet。创建成功后会执行到channelRead方法,我们从这里下手
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
NettyChannel channel = NettyChannel.getOrAddChannel(ctx.channel(), url, handler);
try {
handler.received(channel, msg);
} finally {
NettyChannel.removeChannelIfDisconnected(ctx.channel());
}
}
AbstractPeer.java
public void received(Channel ch, Object msg) throws RemotingException {
if (closed) {
return;
}
handler.received(ch, msg);
}
MultiMessageHandler.java
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 {
handler.received(channel, message); //
}
}
HeartbeatHandler.java
public void received(Channel channel, Object message) throws RemotingException {
setReadTimestamp(channel);
if (isHeartbeatRequest(message)) { // 判断当前message是否是客户端的心跳
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)) { // 判断当前message是否是来自于Server端的心跳响应
if (logger.isDebugEnabled()) {
logger.debug("Receive heartbeat response in thread " + Thread.currentThread().getName());
}
return;
}
handler.received(channel, message); // message是普通数据
}
AllChannelHandler.java
public void received(Channel channel, Object message) throws RemotingException {
ExecutorService executor = getExecutorService(); // 线程池
try { // 将Client发送来处数据包装为一个任务，使用线程池中的线程来完成
executor.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);
}
}
ChannelEventRunnable.java
public void run() {
// 接收到处理任务
if (state == ChannelState.RECEIVED) {
try {
handler.received(channel, message);
} catch (Exception e) {
logger.warn("ChannelEventRunnable handle " + state + " operation error, channel is " + channel
+ ", message is " + message, e);
}
}
......
}
DecodeHandler.java
// 做数据解码
public void received(Channel channel, Object message) throws RemotingException {
if (message instanceof Decodeable) {
decode(message); // 解码消息
}
if (message instanceof Request) {
decode(((Request) message).getData()); // 解码RpcInvocation
}
if (message instanceof Response) {
decode(((Response) message).getResult()); // 解码响应结果
}
// 此时的message是经过解码的
handler.received(channel, message);
}
HeaderExchangeHandler.java
@Override
public void received(Channel channel, Object message) throws RemotingException {
channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis());
final ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel);
try {
if (message instanceof Request) { // 处理message为请求的情况
// handle request.
Request request = (Request) message;
if (request.isEvent()) {
handlerEvent(channel, request);
} else {
if (request.isTwoWay()) {
handleRequest(exchangeChannel, request); // 处理请求
} else {
handler.received(exchangeChannel, request.getData());
}
}
} else if (message instanceof Response) { // 处理message为响应的情况
// 跟踪这里
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);
}
}
static void handleResponse(Channel channel, Response response) throws RemotingException {
if (response != null && !response.isHeartbeat()) {
DefaultFuture.received(channel, response);
}
}
DefaultFuture.java
public static void received(Channel channel, Response response) {
received(channel, response, false);
}
public static void received(Channel channel, Response response, boolean timeout) {
try {
DefaultFuture future = FUTURES.remove(response.getId());
if (future != null) {
Timeout t = future.timeoutCheckTask;
if (!timeout) {
// decrease Time
t.cancel();
}
// 跟这里
future.doReceived(response);
} else {
logger.warn("The timeout response finally returned at "
+ (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(new Date()))
+ ", response " + response
+ (channel == null ? "" : ", channel: " + channel.getLocalAddress()
+ " -> " + channel.getRemoteAddress()));
}
} finally {
CHANNELS.remove(response.getId());
}
}
private void doReceived(Response res) {
if (res == null) {
throw new IllegalStateException("response cannot be null");
}
if (res.getStatus() == Response.OK) {
// 拿到响应结果并逐层返回
this.complete(res.getResult());
} else if (res.getStatus() == Response.CLIENT_TIMEOUT || res.getStatus() == Response.SERVER_TIMEOUT) {
this.completeExceptionally(new TimeoutException(res.getStatus() == Response.SERVER_TIMEOUT, channel, res.getErrorMessage()));
} else {
this.completeExceptionally(new RemotingException(channel, res.getErrorMessage()));
}
}
CompletableFuture.java
public boolean complete(T value) {
boolean triggered = completeValue(value);
postComplete();
return triggered;
}
ProtocolFilterWrapper.java
// 最终返回到了这里
public Result invoke(Invocation invocation) throws RpcException {
Result asyncResult = filterInvoker.invoke(invocation); // 返回一个异步结果
asyncResult = asyncResult.whenCompleteWithContext((r, t) -> {
for (int i = filters.size() - 1; i >= 0; i--) {
Filter filter = filters.get(i);
// onResponse callback
if (filter instanceof ListenableFilter) {
Filter.Listener listener = ((ListenableFilter) filter).listener();
if (listener != null) {
if (t == null) {
listener.onResponse(r, filterInvoker, invocation);
} else {
listener.onError(t, filterInvoker, invocation);
}
}
} else {
filter.onResponse(r, filterInvoker, invocation);
}
}
});
return asyncResult;
}
