Dubbo源码分析之发送请求
作者：互联网
消费端操作InvokerInvocationHandler代理发送请求，组装调用类
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
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]);
}
return invoker.invoke(createInvocation(method, args)).recreate();
}
private RpcInvocation createInvocation(Method method, Object[] args) {
RpcInvocation invocation = new RpcInvocation(method, args);
if (RpcUtils.hasFutureReturnType(method)) {
invocation.setAttachment(Constants.FUTURE_RETURNTYPE_KEY, "true");
invocation.setAttachment(Constants.ASYNC_KEY, "true");
}
return invocation;
}
判断是否是mock调用
public Result invoke(Invocation invocation) throws RpcException {
Result result = null;
String value = directory.getUrl().getMethodParameter(invocation.getMethodName(), Constants.MOCK_KEY, Boolean.FALSE.toString()).trim();
if (value.length() == 0 || value.equalsIgnoreCase("false")) {
//no mock
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
result = doMockInvoke(invocation, null);
} else {
//fail-mock
try {
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);
}
result = doMockInvoke(invocation, e);
}
}
return result;
}
检查集群invoker状态
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);
}
List<Invoker<T>> invokers = list(invocation);
LoadBalance loadbalance = initLoadBalance(invokers, invocation);
RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
return doInvoke(invocation, invokers, loadbalance);
}
从注册明细类中获取所有的invoker远程调用，经过路由链路挑选符合的invoker
protected List<Invoker<T>> list(Invocation invocation) throws RpcException {
return directory.list(invocation);
}
// Get invokers from cache, only runtime routers will be executed.
invokers = routerChain.route(getConsumerUrl(), invocation);
默认获取随机负载均衡
protected LoadBalance initLoadBalance(List<Invoker<T>> invokers, Invocation invocation) {
if (CollectionUtils.isNotEmpty(invokers)) {
return ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
.getMethodParameter(RpcUtils.getMethodName(invocation), Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
} else {
return ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE);
}
}
默认使用失败转移集群调用FailoverClusterInvoker，最多调用三次，从invoker集合中选择本次需要使用的invoker，尽量不使用上次调用失败的invoker。
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, Constants.RETRIES_KEY, Constants.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);
}
Invoker<T> invoker = select(loadbalance, invocation, copyInvokers, invoked);
invoked.add(invoker);
RpcContext.getContext().setInvokers((List) invoked);
try {
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);
}
开始invoker代理包装类调用
class InvokerDelegate<T> extends InvokerWrapper<T>
public Result invoke(Invocation invocation) throws RpcException {
return invoker.invoke(invocation);
}
监听器包装类
class ListenerInvokerWrapper<T>
public Result invoke(Invocation invocation) throws RpcException {
return invoker.invoke(invocation);
}
过滤器ConsumerContextFilter，FutureFilter，MonitorFilter
class ProtocolFilterWrapper$1
public Result invoke(Invocation invocation) throws RpcException {
Result result = filter.invoke(next, invocation);
if (result instanceof AsyncRpcResult) {
AsyncRpcResult asyncResult = (AsyncRpcResult) result;
asyncResult.thenApplyWithContext(r -> filter.onResponse(r, invoker, invocation));
return asyncResult;
} else {
return filter.onResponse(result, invoker, invocation);
}
}
开始准备远程调用，选择一个客户端，判断同异步以及单双向方式，超时时间
class DubboInvoker<T> extends AbstractInvoker<T>
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;
if (clients.length == 1) {
currentClient = clients[0];
} else {
currentClient = clients[index.getAndIncrement() % clients.length];
}
try {
boolean isAsync = RpcUtils.isAsync(getUrl(), invocation);
boolean isAsyncFuture = RpcUtils.isReturnTypeFuture(inv);
boolean isOneway = RpcUtils.isOneway(getUrl(), invocation);
int timeout = getUrl().getMethodParameter(methodName, Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT);
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) {
ResponseFuture future = currentClient.request(inv, timeout);
// For compatibility
FutureAdapter<Object> futureAdapter = new FutureAdapter<>(future);
RpcContext.getContext().setFuture(futureAdapter);
Result result;
if (isAsyncFuture) {
// register resultCallback, sometimes we need the async result being processed by the filter chain.
result = new AsyncRpcResult(futureAdapter, futureAdapter.getResultFuture(), false);
} else {
result = new SimpleAsyncRpcResult(futureAdapter, futureAdapter.getResultFuture(), false);
}
return result;
} else {
RpcContext.getContext().setFuture(null);
return (Result) currentClient.request(inv, timeout).get();
}
} 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);
}
}
同步进行请求
class ReferenceCountExchangeClient implements ExchangeClient
public ResponseFuture request(Object request, int timeout) throws RemotingException {
return client.request(request, timeout);
}
class HeaderExchangeClient implements ExchangeClient
public ResponseFuture request(Object request, int timeout) throws RemotingException {
return channel.request(request, timeout);
}
把请求数据包装为请求Request
class HeaderExchangeChannel implements ExchangeChannel
public ResponseFuture 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);
} catch (RemotingException e) {
future.cancel();
throw e;
}
return future;
}
通过netty开始进行发送请求
class AbstractPeer implements Endpoint, ChannelHandler
public void send(Object message) throws RemotingException {
send(message, url.getParameter(Constants.SENT_KEY, false));
}
class AbstractChannel extends AbstractPeer implements Channel
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());
}
}
把请求写入通道，后续会进行编码发送
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.writeAndFlush(message);
if (sent) {
timeout = getUrl().getPositiveParameter(Constants.TIMEOUT_KEY, Constants.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");
}
}
对写事件进行处理，我们添加监听器以确保我们的写事件是正确的。如果我们的写事件有错误（在大多数情况下编码器失败），我们需要直接返回请求，而不是阻塞调用进程，依次经过各个处理器对发送事件做处理。
class NettyClientHandler extends ChannelDuplexHandler
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
super.write(ctx, msg, promise);
final NettyChannel channel = NettyChannel.getOrAddChannel(ctx.channel(), url, handler);
final boolean isRequest = msg instanceof Request;
// We add listeners to make sure our out bound event is correct.
// If our out bound event has an error (in most cases the encoder fails),
// we need to have the request return directly instead of blocking the invoke process.
promise.addListener(future -> {
try {
if (future.isSuccess()) {
// if our future is success, mark the future to sent.
handler.sent(channel, msg);
return;
}
Throwable t = future.cause();
if (t != null && isRequest) {
Request request = (Request) msg;
Response response = buildErrorResponse(request, t);
handler.received(channel, response);
}
} finally {
NettyChannel.removeChannelIfDisconnected(ctx.channel());
}
});
}
标签：Dubbo,return,invoke,getUrl,request,发送,源码,invoker,invocation 来源： https://blog.csdn.net/ph3636/article/details/91872634