hyperledger fabric 结构分析（二）

接着上图分析，经过Consensus Commit流程生成批数据后，是如何送入到ChainCode呢？我们还是以Invoke命令分析。
1）在consensus的helper中调用chaincode的ExecuteTransactions 进入transaction处理流程
func (h *Helper) ExecTxs(id interface{}, txs []*pb.Transaction) ([]byte, error) {succeededTxs, res, ccevents, txerrs, err := chaincode.ExecuteTransactions(context.Background(), chaincode.DefaultChain, txs)}

2）该函数在core/chaincode 中处理，将命令封装成ChainCode识别的格式。其中的chain对象则是访问ChainCode对应的ChainCodeSupport，这样就说明访问ChainCode的接口类是ChainCodeSupportServer。

func Execute(ctxt context.Context, chain *ChaincodeSupport, t *pb.Transaction) ([]byte, *pb.ChaincodeEvent, error) {ccMsg, err = createTransactionMessage(t.Txid, cMsg)resp, err := chain.Execute(ctxt, chaincode, ccMsg, timeout, t)}
3）该函数在ChainCodeSupport文件中，首先检测ChainCode是否建立成功、能否正常运行。其中chrte.handler的得来是比较复杂的，见下描述
func (chaincodeSupport *ChaincodeSupport) Execute(ctxt context.Context, chaincode string, msg *pb.ChaincodeMessage, timeout time.Duration, tx *pb.Transaction) (*pb.ChaincodeMessage, error) {chrte, ok := chaincodeSupport.chaincodeHasBeenLaunched(chaincode)chrte.handler.sendExecuteMessage(msg, tx)}
3.1）在创建ChainCodeSupport的时候registerChaincodeSupport 调用 NewChaincodeSupport 实例化ChainCodeSupport（start.go），服务器的Name：
protos.ChaincodeSupport

ccStartupTimeout := time.Duration(tOut) * time.MillisecondccSrv := chaincode.NewChaincodeSupport(chainname, peer.GetPeerEndpoint, userRunsCC,ccStartupTimeout, secHelper)//Now that chaincode is initialized, register all system chaincodes.system_chaincode.RegisterSysCCs()pb.RegisterChaincodeSupportServer(grpcServer, ccSrv)

var _ChaincodeSupport_serviceDesc = grpc.ServiceDesc{       ServiceName: "protos.ChaincodeSupport",       HandlerType: (*ChaincodeSupportServer)(nil),       Methods:     []grpc.MethodDesc{},       Streams: []grpc.StreamDesc{              {                     StreamName:    "Register",                     Handler:       _ChaincodeSupport_Register_Handler,                     ServerStreams: true,                     ClientStreams: true,              },       },}
3.2）ChainCode 调用 err := shim.Start(new(SimpleChaincode)) 接入到ChainCodeSupportServer
err := shim.Start(new(SimpleChaincode))
3.3）连接ChainCodeSupprotServer同时调用Register函数
func Start(cc Chaincode) error {chaincodeSupportClient := pb.NewChaincodeSupportClient(clientConn)stream, err := chaincodeSupportClient.Register(context.Background())err = chatWithPeer(chaincodename, stream, cc)}
3.4）与此同时ChainCodeSupportServer会根据Client调用注册函数创建该Stream的Handler处理句柄，创建消息响应循环，等待Client发送命令.(注意该handler就是我们关心的
handler.sendExecuteMessage)
func HandleChaincodeStream(chaincodeSupport *ChaincodeSupport, ctxt context.Context, stream ccintf.ChaincodeStream) error {</span>

deadline, ok := ctxt.Deadline()chaincodeLogger.Debugf("Current context deadline = %s, ok = %v", deadline, ok)handler := newChaincodeSupportHandler(chaincodeSupport, stream)return handler.processStream()}

3.5) 客户端shim/Chaincode发送RegisterMessage

handler.serialSend(&pb.ChaincodeMessage{Type: pb.ChaincodeMessage_REGISTER, Payload: payload})
3.6）对于Server而言，我们刚刚创建了handler又有ProcessStream消息响应循环，这样RegisterMessage就交到了ProcessStream手里，ProcessStream根据消息类型执行命令分发
调用beforeRegisterEvent函数。

func (handler *Handler) beforeRegisterEvent(e *fsm.Event, state string) {err = handler.chaincodeSupport.registerHandler(handler)}
3.7）同理在client端（shim/chaincode）也建立响应的消息响应循环。

4）到目前为止还没有完，我们将invoke命令送给了Client的委托模块Shim进行处理。Shim模块根据来访事件类型送入指定处理函数

func (handler *Handler) enterTransactionState(e *fsm.Event) {msg, ok := e.Args[0].(*pb.ChaincodeMessage)if !ok {e.Cancel(fmt.Errorf("Received unexpected message type"))return}chaincodeLogger.Debugf("[%s]Received %s, invoking transaction on chaincode(Src:%s, Dst:%s)", shorttxid(msg.Txid), msg.Type.String(), e.Src, e.Dst)if msg.Type.String() == pb.ChaincodeMessage_TRANSACTION.String() {// Call the chaincode's Run function to invoke transactionhandler.handleTransaction(msg)}}
5）调用ChainCode的invoke函数

func (handler *Handler) handleTransaction(msg *pb.ChaincodeMessage) {res, err := handler.cc.Invoke(stub, function, params)}

以上分析涉及两个过程 1） consensus结束后如何将命令送入ChainCode 2）ChainCodeSupportServer与ChainCode如何建立通信关系。

画一个 ChainCodeSupportServer与ChainCode如何建立通信关系 图：