Gaea源码阅读（二）：客户端流程

以GaeaClientTest为入口

GaeaInit.init("conf/gaea.config");
/**
* 调用URL 格式:tcp://服务名//接口实现类
* 备注:
* 服务名：需要与gaea.config中的服务名一一对应
* 接口实现类：具体调用接口的接口实现类
*/

final String url = "tcp://demo/NewsService";
INewsService newsService = ProxyFactory.create(INewsService.class, url);
List<News> list = newsService.getNewsByCateID();
for (News news : list) {
System.out.println("ID is " + news.getNewsID() + " title is "
+ news.getTitle());
}

如注释所言，客户端通过Restfull格式url"tcp://serviceName/lookup "访问服务。

关键的一句：INewsService newsService = ProxyFactory.create(INewsService.class,url); ，这句话创建了一个实现了INewsService接口的代理，返回的这个代理对象将作为getNewsByCateID的调用句柄。

让我们看看代理的内部如何实现的，跟踪ProxyFactory.create

InvocationHandler handler = new ProxyStandard(type,serviceName, lookup);
return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
newClass[]{type},
handler);

//代理的作用就是将所有调用转交到Handler

InvocationHandler接口实现类ProxyStandard

public ProxyStandard(Class<?> interfaceClass, String serviceName, String lookup){
this.interfaceClass =interfaceClass;
this.methodCaller = newMethodCaller(serviceName, lookup);
}

InvocationHandler主要由methodCaller完成功能，在invoke()中交给methodCaller
Object obj= methodCaller.doMethodCall(args, method);

MethodCaller机制 //doMethodCall

//准备参数
Type[]typeAry = methodInfo.getGenericParameterTypes();
Class<?>[] clsAry = methodInfo.getParameterTypes();
if (args== null) {
args = newObject[0];
}

Parameter[]paras = new Parameter[args.length];
List<Integer> outParas = newArrayList<Integer>();

if(typeAry != null) {
for (int i = 0;i < typeAry.length; i++) {
if(args[i] instanceof Out) {
paras[i] = newParameter(args[i], clsAry[i], typeAry[i], ParaType.Out);
outParas.add(i);
} else {
paras[i] = newParameter(args[i], clsAry[i], typeAry[i], ParaType.In);
}
}
}

//规范化方法名
StringmethodName = methodInfo.getName();
OperationContract ann =methodInfo.getAnnotation(OperationContract.class);
if (ann !=null) {
if(!ann.methodName().equals(AnnotationUtil.DEFAULT_VALUE)) {
methodName = "$" + ann.methodName();
}
}

ParameterreturnPara = new Parameter(null,methodInfo.getReturnType(), methodInfo.getGenericReturnType());

//调用方法
ServiceProxy proxy = ServiceProxy.getProxy(serviceName);

InvokeResultresult = proxy.invoke(returnPara, lookup,methodName, paras);

//设置返回值
if (result!= null && result.getOutPara() != null) {
for (int i = 0;i < outParas.size() && i < result.getOutPara().length; i++) {
Object op = args[outParas.get(i)];
if(op instanceof Out){
((Out)op).setOutPara(result.getOutPara()[i]);
}
}
}
returnresult.getResult();

这里出现了OperationContract注解，这是在方法上面注解的。注解有一个methodName属性。

关键点是ServiceProxy的getProxy和invoke方法。

ServiceProxy.getProxy：构造ServiceProxy

config =ServiceConfig.GetConfig(serviceName);
dispatcher = newDispatcher(config);

requestTime = config.getSocketPool().getReconnectTime();
intserverCount = 1;
if(dispatcher.GetAllServer()!= null && dispatcher.GetAllServer().size()> 0){
serverCount = dispatcher.GetAllServer().size();
}

ioreconnect =serverCount - 1;

//     count = max {ioreconnect,requestTime}
count = requestTime;

if(ioreconnect > requestTime){
count = ioreconnect;
}

首先读取配置文件中属性为//Service[@name= serviceName]的节点

创建实现负载均衡的dispatcher，在这里创建了Server

for(ServerProfile ser : config.getServers()) {
if(ser.getWeithtRate() > 0) {
Server s = newServer(ser);
if(s.getState() != ServerState.Disable) {
ScoketPool sp = newScoketPool(s, config);
s.setScoketpool(sp);
ServerPool.add(s);
}
}
}

ServiceProxy.Invoke方法

//构造RequestProtocol
RequestProtocol requestProtocol = newRequestProtocol(typeName, methodName, listPara);
ProtocolsendP = new Protocol(createSessionId(),
(byte) config.getServiceid(),
SDPType.Request,
CompressType.UnCompress,
config.getProtocol().getSerializerType(),
PlatformType.Java,
requestProtocol);

ProtocolreceiveP = null;
Serverserver = null;

for(int i = 0;i <= count; i++){
server = dispatcher.GetServer();
if (server== null) {
logger.error("cannotget server");
throw newException("cannot get server");
}
try{
//本地存根调用
receiveP = server.request(sendP);
break;
} catch(IOExceptionio){

} catch(RebootExceptionrb){
this.createReboot(server);
}catch(TimeoutExceptionte){

} catch(Throwable ex){

}
}

if(receiveP== null){
throw newException("userdatatype error!");
}

if(receiveP.getSDPType() == SDPType.Response) {
ResponseProtocol rp = (ResponseProtocol)receiveP.getSdpEntity();
logger.debug("invoketime:" + (System.currentTimeMillis() - watcher) + "ms");
return new InvokeResult(rp.getResult(),rp.getOutpara());
} else if(receiveP.getSDPType()== SDPType.Reset){
logger.info(server.getName()+"server is reboot,system will change normal server!");
this.createReboot(server);
returninvoke(returnType, typeName, methodName, paras);
}else if(receiveP.getSDPType() == SDPType.Exception) {
ExceptionProtocol ep = (ExceptionProtocol)receiveP.getSdpEntity();
throwThrowErrorHelper.throwServiceError(ep.getErrorCode(), ep.getErrorMsg());
} else {
throw newException("userdatatype error!");
}

Server.request()过程

//每个CSocket有个WaitWindows注册了SessionId到WindowData的表

increaseCU();
CSocketsocket = null;
try {
try {//发送消息
socket = this.scoketpool.getSocket();
byte[] data= p.toBytes(socket.isRights(),socket.getDESKey());
socket.registerRec(p.getSessionID());
socket.send(data);
} catch(Throwable ex) {
logger.error("Serverget socket Exception", ex);
throw ex;
}finally {
if(socket!= null){
socket.dispose();
}
}

//接收应答
byte[]buffer = socket.receive(p.getSessionID(), currUserCount);
Protocol result = Protocol.fromBytes(buffer,socket.isRights(),socket.getDESKey());
if (this.state ==ServerState.Testing) {
relive();
}
return result;
} catch(IOException ex) {

} catch(Throwable ex) {

} finally {

}

Receive接收应答时，通过sessionId对应的AutoResetEvent等待

//CSocket.receive
AutoResetEvent event = wd.getEvent();
int timeout= getReadTimeout(socketConfig.getReceiveTimeout(), queueLen);
if(!event.waitOne(timeout)) {
throw newTimeoutException("Receive data timeout or error!timeout:" +timeout + "ms,queue length:" +queueLen);
}

返回应答可能为Response、Reset、Exception

Response -> 返回InvokeResult结构体

Reset -> 重启则再调用invoke(returnType,typeName, methodName, paras)

Exception -> 抛出异常

frameHandler从Socket接收数据,并根据协议反解出session id,然后从waitWindows中取出对应的WindowData,然后调用对应的Event的set()通知CSocket.receive 返回

客户端做的工作主要就是这些