hyperledger fabric0.6 结构分析（三）

本文解决的问题是：本Peer节点如何接收其他节点的数据，接到数据如何处理？

之前两节的分析是命令来源是CLI client，如何连接到Devops服务器、如何发送给Consensus模块、如何发送给ChainCodeSupportClient等。

接下来分析本文要讨论的问题

1）在进行网络初始化的过程中执行以下内容，在创建节点Engine过程中该节点作为客户端的身份连接到其他Peer

 peerServer, err = peer.NewPeerWithEngine(secHelperFunc, helper.GetEngine)

 "code" class="cpp" style="font-size: 15px;">func (p *Impl) chatWithPeer(address string) error {
     peerLogger.Debugf("Initiating Chat with peer address: %s", address)
     conn, err := NewPeerClientConnectionWithAddress(address)
     if err != nil {
         peerLogger.Errorf("Error creating connection to peer address %s: %s", address, err)
         return err
     }
     serverClient := pb.NewPeerClient(conn)
     ctx := context.Background()
     stream, err := serverClient.Chat(ctx)
     if err != nil {
         peerLogger.Errorf("Error establishing chat with peer address %s: %s", address, err)
         return err
     }
     peerLogger.Debugf("Established Chat with peer address: %s", address)
     err = p.handleChat(ctx, stream, true)
     stream.CloseSend()
     if err != nil {
         peerLogger.Errorf("Ending Chat with peer address %s due to error: %s", address, err)
         return err
     }
     return nil
 }

2.在handleChat执行过程中，建立消息循环，而这里的handler.HandleMessage。这个handler之前介绍过，是Engine的消息响应句柄，该消息响应处理来自于Consensus模块

 func (p *Impl) handleChat(ctx context.Context, stream ChatStream, initiatedStream bool) error {
     deadline, ok := ctx.Deadline()
     peerLogger.Debugf("Current context deadline = %s, ok = %v", deadline, ok)
     handler, err := p.handlerFactory(p, stream, initiatedStream, nil)
     if err != nil {
         return fmt.Errorf("Error creating handler during handleChat initiation: %s", err)
     }
     defer handler.Stop()
     for {
         in, err := stream.Recv()
         if err == io.EOF {
             peerLogger.Debug("Received EOF, ending Chat")
             return nil
         }
         if err != nil {
             e := fmt.Errorf("Error during Chat, stopping handler: %s", err)
             peerLogger.Error(e.Error())
             return e
         }
         err = handler.HandleMessage(in)
         if err != nil {
             peerLogger.Errorf("Error handling message: %s", err)
             //return err
         }
     }
 }

3.HandleMessage函数consenterChan 这个channel比较重要，该写入操作会触发engine.consensusFan的消息循环

func (handler *ConsensusHandler) HandleMessage(msg *pb.Message) error {
    if msg.Type == pb.Message_CONSENSUS {
        senderPE, _ := handler.To()
        select {
        case handler.consenterChan <- &util.Message{
            Msg:    msg,
            Sender: senderPE.ID,
        }:
            return nil
        default:
            err := fmt.Errorf("Message channel for %v full, rejecting", senderPE.ID)
            logger.Errorf("Failed to queue consensus message because: %v", err)
            return err
        }
    }

    if logger.IsEnabledFor(logging.DEBUG) {
        logger.Debugf("Did not handle message of type %s, passing on to next MessageHandler", msg.Type)
    }
    return handler.MessageHandler.HandleMessage(msg)
}

4.看到RecvMsg这个函数是不是有点眼熟，这个操作和  hyperledger fabric 结构分析 最后一个流程是一样的。

func GetEngine(coord peer.MessageHandlerCoordinator) (peer.Engine, error) {
    var err error
    engineOnce.Do(func() {
        engine = new(EngineImpl)
        engine.helper = NewHelper(coord)
        engine.consenter = controller.NewConsenter(engine.helper)
        engine.helper.setConsenter(engine.consenter)
        engine.peerEndpoint, err = coord.GetPeerEndpoint()
        engine.consensusFan = util.NewMessageFan()

        go func() {
            logger.Debug("Starting up message thread for consenter")

            // The channel never closes, so this should never break
            for msg := range engine.consensusFan.GetOutChannel() {
                engine.consenter.RecvMsg(msg.Msg, msg.Sender)
            }
        }()
    })
    return engine, err
}

5.再往下的流程与 hyperledger fabric 结构分析（三）中的一致。