區塊鏈教程Fabric1.0原始碼分析PeerBroadcastClient（Broadcast客戶端），2018年下半年，區塊鏈行業正逐漸褪去發展之初的浮躁、迴歸理性，表面上看相關人才需求與身價似乎正在回落。但事實上，正是初期泡沫的漸退，讓人們更多的關注點放在了區塊鏈真正的技術之上。

Fabric1.0原始碼筆記之Peer DeliverClient（Deliver客戶端）

1、DeliverClient概述

DeliverClient程式碼分佈如下：

• peer/channel/deliverclient.go，deliverClientIntf介面定義及實現，以及DeliverClient工具函式。
• protos/orderer/ab.pb.go，AtomicBroadcast_DeliverClient介面定義和實現。

2、deliverClientIntf介面定義及實現

2.1、DeliverClient工具函式

//構造deliverClient
func newDeliverClient(conn *grpc.ClientConn, client ab.AtomicBroadcast_DeliverClient, chainID string) *deliverClient
//程式碼在peer/channel/deliverclient.go

2.2、deliverClientIntf介面定義及實現

type deliverClientIntf interface {
    getSpecifiedBlock(num uint64) (*common.Block, error)
    getOldestBlock() (*common.Block, error)
    getNewestBlock() (*common.Block, error)
    Close() error
}

type deliverClient struct {
    conn    *grpc.ClientConn
    client  ab.AtomicBroadcast_DeliverClient
    chainID string
}

//構造查詢Envelope
func seekHelper(chainID string, position *ab.SeekPosition) *common.Envelope
//r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Specified{Specified: &ab.SeekSpecified{Number: blockNumber}}}))
func (r *deliverClient) seekSpecified(blockNumber uint64) error
//r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Oldest{Oldest: &ab.SeekOldest{}}}))
func (r *deliverClient) seekOldest() error
//return r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Newest{Newest: &ab.SeekNewest{}}}))
func (r *deliverClient) seekNewest() error
//r.client.Recv()讀取塊
func (r *deliverClient) readBlock() (*common.Block, error)
//r.seekSpecified(num)和r.readBlock()
func (r *deliverClient) getSpecifiedBlock(num uint64) (*common.Block, error)
//r.seekOldest()和r.readBlock()
func (r *deliverClient) getOldestBlock() (*common.Block, error)
//r.seekNewest()和r.readBlock()
func (r *deliverClient) getNewestBlock() (*common.Block, error)
//r.conn.Close()
func (r *deliverClient) Close() error
//cf.DeliverClient.getSpecifiedBlock(0)獲取創世區塊
func getGenesisBlock(cf *ChannelCmdFactory) (*common.Block, error)
//程式碼在peer/channel/deliverclient.go
 

func seekHelper(chainID string, position ab.SeekPosition) common.Envelope程式碼如下：

func seekHelper(chainID string, position *ab.SeekPosition) *common.Envelope {
    seekInfo := &ab.SeekInfo{
        Start:    position,
        Stop:     position,
        Behavior: ab.SeekInfo_BLOCK_UNTIL_READY,
    }

    msgVersion := int32(0)
    epoch := uint64(0)
    env, err := utils.CreateSignedEnvelope(common.HeaderType_CONFIG_UPDATE, chainID, localmsp.NewSigner(), seekInfo, msgVersion, epoch)
    return env
}
//程式碼在peer/channel/deliverclient.go

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