开篇
- 这篇是Dubbo Provider 处理请求流程 (1)的下篇内容，建议有兴趣可以先阅读之前的Dubbo Provider 处理请求流程 (1)，能够更好的进行串联。
Dubbo Protocol调用链
DubboProtocol调用链
DubboProtocol调用栈
- 调用链核心在于DubboProtocol => xxxFilter => AbstractProxyInvoker。
DubboProtocol调用分析
DubboProtocol
public class DubboProtocol extends AbstractProtocol {
public static final String NAME = "dubbo";
public static final int DEFAULT_PORT = 20880;
private static final String IS_CALLBACK_SERVICE_INVOKE = "_isCallBackServiceInvoke";
private static DubboProtocol INSTANCE;
private final Map serverMap = new ConcurrentHashMap(); //
private final Map referenceClientMap = new ConcurrentHashMap(); //
private final ConcurrentMap ghostClientMap = new ConcurrentHashMap();
private final ConcurrentMap locks = new ConcurrentHashMap();
private final Set optimizers = new ConcurrentHashSet();
//consumer side export a stub service for dispatching event
//servicekey-stubmethods
private final ConcurrentMap stubServiceMethodsMap = new ConcurrentHashMap();
private ExchangeHandler requestHandler = new ExchangeHandlerAdapter() {
@Override
public Object reply(ExchangeChannel channel, Object message) throws RemotingException {
if (message instanceof Invocation) {
Invocation inv = (Invocation) message;
// 查找对应的invoker
Invoker invoker = getInvoker(channel, inv);
// 省略一些无关代码
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 {
// 省略非核心代码
String serviceKey = serviceKey(port, path, inv.getAttachments().get(Constants.VERSION_KEY), inv.getAttachments().get(Constants.GROUP_KEY));
DubboExporter exporter = (DubboExporter) exporterMap.get(serviceKey);
if (exporter == null)
throw new RemotingException(channel, "Not found exported service: " + serviceKey + " in " + exporterMap.keySet() + ", may be version or group mismatch " + ", channel: consumer: " + channel.getRemoteAddress() + " --> provider: " + channel.getLocalAddress() + ", message:" + inv);
return exporter.getInvoker();
}
}
public class ProtocolUtils {
public static String serviceKey(int port, String serviceName, String serviceVersion, String serviceGroup) {
StringBuilder buf = new StringBuilder();
if (serviceGroup != null && serviceGroup.length() > 0) {
buf.append(serviceGroup);
buf.append("/");
}
buf.append(serviceName);
if (serviceVersion != null && serviceVersion.length() > 0 && !"0.0.0".equals(serviceVersion)) {
buf.append(":");
buf.append(serviceVersion);
}
buf.append(":");
buf.append(port);
return buf.toString();
}
}
- DubboProtocol的getInvoker通过serviceKey()方法生成key从exproterMap获取对应的exporter，进而通过exporter.getInvoker获取对应的invoker对象。
- 通过invoker.invoke()调用，开始进入各类Filter的调用。
ProtocolFilterWrapper
public class ProtocolFilterWrapper implements Protocol {
private final Protocol protocol;
public ProtocolFilterWrapper(Protocol protocol) {
if (protocol == null) {
throw new IllegalArgumentException("protocol == null");
}
this.protocol = protocol;
}
private static Invoker buildInvokerChain(final Invoker invoker, String key, String group) {
Invoker last = invoker;
List 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 next = last;
// 匿名函数类的写法
last = new Invoker() {
// 省略一些非核心代码
@Override
public Result invoke(Invocation invocation) throws RpcException {
return filter.invoke(next, invocation);
}
// 省略一些非核心代码
};
}
}
return last;
}
}
public class EchoFilter implements Filter {
@Override
public Result invoke(Invoker invoker, Invocation inv) throws RpcException {
if (inv.getMethodName().equals(Constants.$ECHO) && inv.getArguments() != null && inv.getArguments().length == 1)
return new RpcResult(inv.getArguments()[0]);
return invoker.invoke(inv);
}
}
- ProtocolFilterWrapper通过buildInvokerChain()方法构建调用链，通过调用链层层调用。
- ProtocolFilterWrapper的Filter链的构造过程使用了匿名函数的一些特性。
- 以EchoFilter为例子说明Filter的调用方式。
JavassistProxyFactory
public abstract class AbstractProxyInvoker implements Invoker {
private final T proxy;
private final Class type;
private final URL url;
@Override
public Result invoke(Invocation invocation) throws RpcException {
try {
return new RpcResult(doInvoke(proxy, invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments()));
} catch (InvocationTargetException e) {
return new RpcResult(e.getTargetException());
} catch (Throwable e) {
throw new RpcException("Failed to invoke remote proxy method " + invocation.getMethodName() + " to " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
protected abstract Object doInvoke(T proxy, String methodName, Class[] parameterTypes, Object[] arguments) throws Throwable;
}
public class JavassistProxyFactory extends AbstractProxyFactory {
@Override
@SuppressWarnings("unchecked")
public T getProxy(Invoker invoker, Class[] interfaces) {
return (T) Proxy.getProxy(interfaces).newInstance(new InvokerInvocationHandler(invoker));
}
@Override
public Invoker getInvoker(T proxy, Class type, URL url) {
// TODO Wrapper cannot handle this scenario correctly: the classname contains '$'
final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);
return new AbstractProxyInvoker(proxy, type, url) {
@Override
protected Object doInvoke(T proxy, String methodName,
Class[] parameterTypes,
Object[] arguments) throws Throwable {
return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);
}
};
}
}
- JavassistProxyFactory的getInvoker()方法返回AbstractProxyInvoker对象。
- AbstractProxyInvoker内部调用wrapper对象的invokeMethod()方法进行处理。
Wrapper
package org.apache.dubbo.common.bytecode;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;
import org.apache.dubbo.common.bytecode.ClassGenerator;
import org.apache.dubbo.common.bytecode.NoSuchMethodException;
import org.apache.dubbo.common.bytecode.NoSuchPropertyException;
import org.apache.dubbo.common.bytecode.Wrapper;
import org.apache.dubbo.demo.provider.DemoServiceImpl;
public class Wrapper1 extends Wrapper implements ClassGenerator.DC {
public static String[] pns;
public static Map pts;
public static String[] mns;
public static String[] dmns;
public static Class[] mts0;
public Object invokeMethod(Object object, String string, Class[] arrclass, Object[] arrobject) throws InvocationTargetException {
DemoServiceImpl demoServiceImpl;
try {
demoServiceImpl = (DemoServiceImpl)object;
}
catch (Throwable throwable) {
throw new IllegalArgumentException(throwable);
}
try {
if ("sayHello".equals(string) && arrclass.length == 1) {
return demoServiceImpl.sayHello((String)arrobject[0]);
}
}
catch (Throwable throwable) {
throw new InvocationTargetException(throwable);
}
throw new NoSuchMethodException(new StringBuffer().append("Not found method \"").append(string).append("\" in class org.apache.dubbo.demo.provider.DemoServiceImpl.").toString());
}
}
- wrapper对象是动态生成的类对象，内部直接调用serviceImpl的对象进行处理。