币安Binance交易所-币安官网注册-币安HT行情价格

Go语言区块链教程Fabric1.0源代码分析Ledger历史数据库

作者:小雷 2021-08-30

  Go语言+区块链教程Fabric1.0源代码分析Ledger historydb历史数据库,2018年下半年,区块链行业正逐渐褪去发展之初的浮躁、回归理性,表面上看相关人才需求与身价似乎正在回落。但事实上,正是初期泡沫的渐退,让人们更多的关注点放在了区块链真正的技术之上。

  ## 1、historydb概述

  historydb,用于存储所有块读写集中写集的内容。

  代码分布在core/ledger/kvledger/history/historydb目录下,目录结构如下:

  * historydb.go,定义核心接口HistoryDBProvider和HistoryDB。

  * histmgr_helper.go,historydb工具函数。

  * historyleveldb目录,historydb基于leveldb的实现。

      * historyleveldb.go,HistoryDBProvider和HistoryDB接口实现,即historyleveldb.HistoryDBProvider和historyleveldb.historyDB结构体及方法。

      * historyleveldb_query_executer.go,定义LevelHistoryDBQueryExecutor和historyScanner结构体及方法。

  ## 2、核心接口定义

  HistoryDBProvider接口定义:

  ```go

  type HistoryDBProvider interface {

      GetDBHandle(id string) (HistoryDB, error) //获取HistoryDB

      Close() //关闭所有HistoryDB

  //代码在core/ledger/kvledger/history/historydb/historydb.go

  HistoryDB接口定义:

  ```go

  type HistoryDB interface {

      //构造 LevelHistoryDBQueryExecutor

      NewHistoryQueryExecutor(blockStore blkstorage.BlockStore) (ledger.HistoryQueryExecutor, error)

      //提交Block入historyDB

      Commit(block *common.Block) error

      //获取savePointKey,即version.Height

      GetLastSavepoint() (*version.Height, error)

      //是否应该恢复,比较lastAvailableBlock和Savepoint

      ShouldRecover(lastAvailableBlock uint64) (bool, uint64, error)

      //提交丢失的块

      CommitLostBlock(block *common.Block) error

  //代码在core/ledger/kvledger/history/historydb/historydb.go

  补充ledger.HistoryQueryExecutor接口定义:执行历史记录查询。

  ```go

  type HistoryQueryExecutor interface {

      GetHistoryForKey(namespace string, key string) (commonledger.ResultsIterator, error) //按key查历史记录

  //代码在core/ledger/ledger_interface.go

  ## 3、historydb工具函数

  ```go

  //构造复合HistoryKey,ns 0x00 key 0x00 blocknum trannum

  func ConstructCompositeHistoryKey(ns string, key string, blocknum uint64, trannum uint64) []byte

  //构造部分复合HistoryKey,ns 0x00 key 0x00 0xff

  func ConstructPartialCompositeHistoryKey(ns string, key string, endkey bool) []byte

  //按分隔符separator,分割bytesToSplit

  func SplitCompositeHistoryKey(bytesToSplit []byte, separator []byte) ([]byte, []byte)

  //代码在core/ledger/kvledger/history/historydb/histmgr_helper.go

  ## 4、HistoryDB接口实现

  HistoryDB接口实现,即historyleveldb.historyDB结构体及方法。historyDB结构体定义如下:

  ```go

  type historyDB struct {

      db *leveldbhelper.DBHandle //leveldb

      dbName string //dbName

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb.go

  涉及方法如下:

  ```go

  //构造historyDB

  func newHistoryDB(db *leveldbhelper.DBHandle, dbName string) *historyDB

  //do nothing

  func (historyDB *historyDB) Open() error

  //do nothing

  func (historyDB *historyDB) Close()

  //提交Block入historyDB,将读写集中写集入库,并更新savePointKey

  func (historyDB *historyDB) Commit(block *common.Block) error

  //构造 LevelHistoryDBQueryExecutor

  func (historyDB *historyDB) NewHistoryQueryExecutor(blockStore blkstorage.BlockStore) (ledger.HistoryQueryExecutor, error)

  获取savePointKey,即version.Height

  func (historyDB *historyDB) GetLastSavepoint() (*version.Height, error)

  //是否应该恢复,比较lastAvailableBlock和Savepoint

  func (historyDB *historyDB) ShouldRecover(lastAvailableBlock uint64) (bool, uint64, error)

  //提交丢失的块,即调用historyDB.Commit(block)

  func (historyDB *historyDB) CommitLostBlock(block *common.Block) error

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb.go

  func (historyDB *historyDB) Commit(block *common.Block) error代码如下:

  ```go

  blockNo := block.Header.Number //区块编号

  var tranNo uint64 //交易编号,初始化值为0

  dbBatch := leveldbhelper.NewUpdateBatch() //leveldb批量更新

  //交易验证代码,type TxValidationFlags []uint8

  //交易筛选器

  txsFilter := util.TxValidationFlags(block.Metadata.Metadata[common.BlockMetadataIndex_TRANSACTIONS_FILTER])

  if len(txsFilter) == 0 {

      txsFilter = util.NewTxValidationFlags(len(block.Data.Data))

      block.Metadata.Metadata[common.BlockMetadataIndex_TRANSACTIONS_FILTER] = txsFilter

  for _, envBytes := range block.Data.Data {

      if txsFilter.IsInvalid(int(tranNo)) { //检查指定的交易是否有效

          tranNo++

          continue

      //[]byte反序列化为Envelope

      env, err := putils.GetEnvelopeFromBlock(envBytes)

      payload, err := putils.GetPayload(env) //e.Payload反序列化为Payload

      //[]byte反序列化为ChannelHeader

      chdr, err := putils.UnmarshalChannelHeader(payload.Header.ChannelHeader)

      if common.HeaderType(chdr.Type) == common.HeaderType_ENDORSER_TRANSACTION { //背书交易,type HeaderType int32

          respPayload, err := putils.GetActionFromEnvelope(envBytes) //获取ChaincodeAction

          txRWSet := rwsetutil.TxRwSet{}

          err = txRWSet.FromProtoBytes(respPayload.Results) //[]byte反序列化后构造NsRwSet,加入txRWSet.NsRwSets

          for _, nsRWSet := range txRWSet.NsRwSets {

              ns := nsRWSet.NameSpace

              for _, kvWrite := range nsRWSet.KvRwSet.Writes {

                  writeKey := kvWrite.Key

                  //txRWSet中写集入库

                  compositeHistoryKey := historydb.ConstructCompositeHistoryKey(ns, writeKey, blockNo, tranNo)

                  dbBatch.Put(compositeHistoryKey, emptyValue)

      } else {

          logger.Debugf("Skipping transaction [%d] since it is not an endorsement transaction\n", tranNo)

      tranNo++

  height := version.NewHeight(blockNo, tranNo)

  dbBatch.Put(savePointKey, height.ToBytes())

  err := historyDB.db.WriteBatch(dbBatch, true)

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb.go

  Tx(Transaction 交易)相关更详细内容,参考:[Fabric 1.0源代码笔记 之 Tx(Transaction 交易)](../tx/README.md)

  ## 5、HistoryDBProvider接口实现

  HistoryDBProvider接口实现,即historyleveldb.HistoryDBProvider结构体和方法。

  ```go

  type HistoryDBProvider struct {

      dbProvider *leveldbhelper.Provider

  //构造HistoryDBProvider

  func NewHistoryDBProvider() *HistoryDBProvider

  //获取HistoryDB

  func (provider *HistoryDBProvider) GetDBHandle(dbName string) (historydb.HistoryDB, error)

  //关闭所有HistoryDB句柄,调取provider.dbProvider.Close()

  func (provider *HistoryDBProvider) Close()

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb.go

  ## 6、LevelHistoryDBQueryExecutor和historyScanner结构体及方法

  LevelHistoryDBQueryExecutor结构体及方法:实现ledger.HistoryQueryExecutor接口。

  ```go

  type LevelHistoryDBQueryExecutor struct {

      historyDB *historyDB

      blockStore blkstorage.BlockStore //用于传递给historyScanner

  //按key查historyDB,调用q.historyDB.db.GetIterator(compositeStartKey, compositeEndKey)

  func (q *LevelHistoryDBQueryExecutor) GetHistoryForKey(namespace string, key string) (commonledger.ResultsIterator, error)

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb_query_executer.go

  historyScanner结构体及方法:实现ledger.ResultsIterator接口。

  ```go

  type historyScanner struct {

      compositePartialKey []byte //ns 0x00 key 0x00

      namespace string

      key string

      dbItr iterator.Iterator //leveldb迭代器

      blockStore blkstorage.BlockStore

  //构造historyScanner

  func newHistoryScanner(compositePartialKey []byte, namespace string, key string, dbItr iterator.Iterator, blockStore blkstorage.BlockStore) *historyScanner

  //按迭代器中key取blockNum和tranNum,再按blockNum和tranNum从blockStore中取Envelope,然后从Envelope的txRWSet.NsRwSets中按key查找并构造queryresult.KeyModification

  func (scanner *historyScanner) Next() (commonledger.QueryResult, error)

  func (scanner *historyScanner) Close() //scanner.dbItr.Release()

  从Envelope的txRWSet.NsRwSets中按key查找并构造queryresult.KeyModification

  func getKeyModificationFromTran(tranEnvelope *common.Envelope, namespace string, key string) (commonledger.QueryResult, error)

  //代码在core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb_query_executer.go

  补充queryresult.KeyModification:

  ```go

  type KeyModification struct {

      TxId string //交易ID,ChannelHeader.TxId

      Value []byte //读写集中Value,KVWrite.Value

      Timestamp *google_protobuf.Timestamp //ChannelHeader.Timestamp

      IsDelete bool //KVWrite.IsDelete

  //代码在protos/ledger/queryresult/kv_query_result.pb.go

目前有 0 条留言

发表留言

◎欢迎参与讨论,请在这里发表您的看法、交流您的观点。