# Fabric 1.0源代码笔记 之 Tx（Transaction 交易）
## 1、Tx概述
Tx，即Transaction，交易或事务。
Tx代码分布目录结构如下：
* protos/common/common.pb.go，交易的封装即Envelope结构体。也包括Payload、Header、ChannelHeader和SignatureHeader。
* protos/utils目录，交易相关部分工具函数，包括txutils.go、proputils.go和commonutils.go。
* core/ledger/kvledger/txmgmt目录
* rwsetutil目录，读写集相关结构体及方法。
* version目录，version.Height结构体及方法。
* validator目录，Validator接口及实现。
* txmgr目录，TxMgr接口及实现。
## 2、交易的封装Envelope结构体
### 2.1、Envelope结构体
Envelope直译为信封，封装Payload和Signature。
```go
type Envelope struct { //用签名包装Payload，以便对信息做身份验证
Payload [] byte //Payload序列化
Signature [] byte //Payload header中指定的创建者签名
}
//代码在protos/common/common.pb.go
```
### 2.2、Payload相关结构体
Payload直译为有效载荷。Payload结构体：
```go
type Payload struct {
Header *Header //Header
Data [] byte //Transaction序列化
}
//代码在protos/common/common.pb.go
```
Header结构体：
```go
type Header struct {
ChannelHeader [] byte
SignatureHeader [] byte
}
//代码在protos/common/common.pb.go
```
ChannelHeader结构体：
```go
type ChannelHeader struct {
Type int32
Version int32 //消息协议版本
Timestamp *google_protobuf.Timestamp //创建消息时的本地时间
ChannelId string //消息绑定的ChannelId
TxId string //TxId
Epoch uint64 //纪元
Extension [] byte //可附加的扩展
}
//代码在protos/common/common.pb.go
```
补充HeaderType:
```go
type HeaderType int32
const (
HeaderType_MESSAGE HeaderType = 0
HeaderType_CONFIG HeaderType = 1
HeaderType_CONFIG_UPDATE HeaderType = 2
HeaderType_ENDORSER_TRANSACTION HeaderType = 3
HeaderType_ORDERER_TRANSACTION HeaderType = 4
HeaderType_DELIVER_SEEK_INFO HeaderType = 5
HeaderType_CHAINCODE_PACKAGE HeaderType = 6
)
//代码在protos/common/common.pb.go
```
SignatureHeader结构体：
```go
type SignatureHeader struct {
Creator [] byte //消息的创建者, 指定为证书链
Nonce [] byte //可能只使用一次的任意数字，可用于检测重播攻击
}
//代码在protos/common/common.pb.go
```
### 2.3、Transaction相关结构体
Transaction结构体：
```go
type Transaction struct {
Actions []*TransactionAction //Payload.Data是个TransactionAction数组，容纳每个交易
}
//代码在protos/peer/transaction.pb.go
```
TransactionAction结构体：
```go
type TransactionAction struct {
Header [] byte
Payload [] byte
}
//代码在protos/peer/transaction.pb.go
```
### 2.4、ChaincodeActionPayload相关结构体
ChaincodeActionPayload结构体：
```go
type ChaincodeActionPayload struct {
ChaincodeProposalPayload [] byte
Action *ChaincodeEndorsedAction
}
//代码在protos/peer/transaction.pb.go
```
ChaincodeEndorsedAction结构体：
```go
type ChaincodeEndorsedAction struct {
ProposalResponsePayload [] byte //ProposalResponsePayload序列化
Endorsements []*Endorsement
}
//代码在protos/peer/transaction.pb.go
```
ProposalResponsePayload结构体：
```go
type ProposalResponsePayload struct {
ProposalHash [] byte
Extension [] byte //ChaincodeAction序列化
}
//代码在protos/peer/proposal_response.pb.go
```
ChaincodeAction结构体：
```go
type ChaincodeAction struct {
Results [] byte //TxRwSet序列化
Events [] byte
Response *Response
ChaincodeId *ChaincodeID
}
//代码在protos/peer/proposal.pb.go
```
## 3、交易验证代码TxValidationFlags
TxValidationFlags是交易验证代码的数组，在commiter验证块时使用。
```go
type TxValidationFlags [] uint8
//创建TxValidationFlags数组
func NewTxValidationFlags(size int) TxValidationFlags
//为指定的交易设置交易验证代码
func (obj TxValidationFlags) SetFlag(txIndex int, flag peer.TxValidationCode)
//获取指定交易的交易验证代码
func (obj TxValidationFlags) Flag(txIndex int) peer.TxValidationCode
//检查指定的交易是否有效
func (obj TxValidationFlags) IsValid(txIndex int) bool
//检查指定的交易是否无效
func (obj TxValidationFlags) IsInvalid(txIndex int) bool
//指定交易的交易验证代码与flag比较，相同为true
func (obj TxValidationFlags) IsSetTo(txIndex int, flag peer.TxValidationCode) bool
//代码在core/ledger/util/txvalidationflags.go
```
补充peer.TxValidationCode：
```go
type TxValidationCode int32
const (
TxValidationCode_VALID TxValidationCode = 0
TxValidationCode_NIL_ENVELOPE TxValidationCode = 1
TxValidationCode_BAD_PAYLOAD TxValidationCode = 2
TxValidationCode_BAD_COMMON_HEADER TxValidationCode = 3
TxValidationCode_BAD_CREATOR_SIGNATURE TxValidationCode = 4
TxValidationCode_INVALID_ENDORSER_TRANSACTION TxValidationCode = 5
TxValidationCode_INVALID_CONFIG_TRANSACTION TxValidationCode = 6
TxValidationCode_UNSUPPORTED_TX_PAYLOAD TxValidationCode = 7
TxValidationCode_BAD_PROPOSAL_TXID TxValidationCode = 8
TxValidationCode_DUPLICATE_TXID TxValidationCode = 9
TxValidationCode_ENDORSEMENT_POLICY_FAILURE TxValidationCode = 10
TxValidationCode_MVCC_READ_CONFLICT TxValidationCode = 11
TxValidationCode_PHANTOM_READ_CONFLICT TxValidationCode = 12
TxValidationCode_UNKNOWN_TX_TYPE TxValidationCode = 13
TxValidationCode_TARGET_CHAIN_NOT_FOUND TxValidationCode = 14
TxValidationCode_MARSHAL_TX_ERROR TxValidationCode = 15
TxValidationCode_NIL_TXACTION TxValidationCode = 16
TxValidationCode_EXPIRED_CHAINCODE TxValidationCode = 17
TxValidationCode_CHAINCODE_VERSION_CONFLICT TxValidationCode = 18
TxValidationCode_BAD_HEADER_EXTENSION TxValidationCode = 19
TxValidationCode_BAD_CHANNEL_HEADER TxValidationCode = 20
TxValidationCode_BAD_RESPONSE_PAYLOAD TxValidationCode = 21
TxValidationCode_BAD_RWSET TxValidationCode = 22
TxValidationCode_ILLEGAL_WRITESET TxValidationCode = 23
TxValidationCode_INVALID_OTHER_REASON TxValidationCode = 255
)
//代码在protos/peer/transaction.pb.go
```
## 4、交易相关部分工具函数（protos/utils包）
putils更详细内容，参考：[ Fabric 1.0源代码笔记 之 putils（protos/utils工具包）]
## 5、RWSet（读写集）
RWSet更详细内容，参考：[ Fabric 1.0源代码笔记 之 Tx #RWSet（读写集）]
## 6、version.Height结构体及方法
```go
type Height struct {
BlockNum uint64 //区块编号
TxNum uint64 //交易编号
}
func NewHeight(blockNum, txNum uint64) *Height //构造Height
func NewHeightFromBytes(b [] byte) (*Height, int) //[]byte反序列化构造Height
func (h *Height) ToBytes() [] byte //Height序列化
func (h *Height) Compare(h1 *Height) int //比较两个Height
func AreSame(h1 *Height, h2 *Height) bool //比较两个Height是否相等
//代码在core/ledger/kvledger/txmgmt/version/version.go
```
## 7、Validator接口及实现（验证读写集）
### 7.1、Validator接口定义
```go
type Validator interface {
//验证和准备批处理
ValidateAndPrepareBatch(block *common.Block, doMVCCValidation bool) (*statedb.UpdateBatch, error)
}
//代码在core/ledger/kvledger/txmgmt/validator/validator.go
```
### 7.2、Validator接口实现
Validator接口实现，即statebasedval.Validator结构体及方法。Validator结构体定义如下：
```go
type Validator struct {
db statedb.VersionedDB //statedb
}
//代码在core/ledger/kvledger/txmgmt/validator/statebasedval/state_based_validator.go
```
涉及方法如下：
```go
//构造Validator
func NewValidator(db statedb.VersionedDB) *Validator
//验证背书交易
func (v *Validator) validateEndorserTX(envBytes [] byte, doMVCCValidation bool, updates *statedb.UpdateBatch) (*rwsetutil.TxRwSet, peer.TxValidationCode, error)
//验证和准备批处理，Block中写集加入批处理
func (v *Validator) ValidateAndPrepareBatch(block *common.Block, doMVCCValidation bool) (*statedb.UpdateBatch, error)
func addWriteSetToBatch(txRWSet *rwsetutil.TxRwSet, txHeight *version.Height, batch *statedb.UpdateBatch)
func (v *Validator) validateTx(txRWSet *rwsetutil.TxRwSet, updates *statedb.UpdateBatch) (peer.TxValidationCode, error)
func (v *Validator) validateReadSet(ns string, kvReads []*kvrwset.KVRead, updates *statedb.UpdateBatch) ( bool, error)
func (v *Validator) validateKVRead(ns string, kvRead *kvrwset.KVRead, updates *statedb.UpdateBatch) ( bool, error)
func (v *Validator) validateRangeQueries(ns string, rangeQueriesInfo []*kvrwset.RangeQueryInfo, updates *statedb.UpdateBatch) ( bool, error)
func (v *Validator) validateRangeQuery(ns string, rangeQueryInfo *kvrwset.RangeQueryInfo, updates *statedb.UpdateBatch) ( bool, error)
//代码在core/ledger/kvledger/txmgmt/validator/statebasedval/state_based_validator.go
```
func (v *Validator) ValidateAndPrepareBatch(block *common.Block, doMVCCValidation bool) (*statedb.UpdateBatch, error)代码如下：
```go
updates := statedb.NewUpdateBatch() //构造批处理
//type TxValidationFlags []uint8
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 txIndex, envBytes := range block.Data.Data {
if txsFilter.IsInvalid(txIndex) { //验证交易是否有效
continue
}
env, err := putils.GetEnvelopeFromBlock(envBytes) //Envelope
payload, err := putils.GetPayload(env) //Payload
chdr, err := putils.UnmarshalChannelHeader(payload.Header.ChannelHeader) //ChannelHeader
txType := common.HeaderType(chdr.Type) //HeaderType
if txType != common.HeaderType_ENDORSER_TRANSACTION {
continue
}
//验证背书交易，获取读写集
txRWSet, txResult, err := v.validateEndorserTX(envBytes, doMVCCValidation, updates)
txsFilter.SetFlag(txIndex, txResult)
if txRWSet != nil {
committingTxHeight := version.NewHeight(block.Header.Number, uint64(txIndex))
//读写集中写集加入批处理
addWriteSetToBatch(txRWSet, committingTxHeight, updates)
txsFilter.SetFlag(txIndex, peer.TxValidationCode_VALID)
}
}
block.Metadata.Metadata[common.BlockMetadataIndex_TRANSACTIONS_FILTER] = txsFilter
return updates, nil
//代码在core/ledger/kvledger/txmgmt/validator/statebasedval/state_based_validator.go
```
## 8、TxMgr接口及实现（交易管理）
### 8.1、TxMgr接口定义
```go
type TxMgr interface {
NewQueryExecutor() (ledger.QueryExecutor, error)
NewTxSimulator() (ledger.TxSimulator, error)
ValidateAndPrepare(block *common.Block, doMVCCValidation bool) error
//返回statedb一致的最高事务的高度
GetLastSavepoint() (*version.Height, error)
ShouldRecover(lastAvailableBlock uint64) ( bool, uint64, error)
CommitLostBlock(block *common.Block) error
Commit() error
Rollback()
Shutdown()
}
//代码在core/ledger/kvledger/txmgmt/txmgr/txmgr.go
```
### 8.2、TxMgr接口实现
TxMgr接口实现，即LockBasedTxMgr结构体及方法。LockBasedTxMgr结构体如下：
```go
type LockBasedTxMgr struct {
db statedb.VersionedDB //statedb
validator validator.Validator //Validator
batch *statedb.UpdateBatch //批处理
currentBlock *common.Block //Block
commitRWLock sync.RWMutex //锁
}
//代码在core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/lockbased_txmgr.go
```
涉及方法如下：
```go
//构造LockBasedTxMgr
func NewLockBasedTxMgr(db statedb.VersionedDB) *LockBasedTxMgr
//调取txmgr.db.GetLatestSavePoint()，返回statedb一致的最高事务的高度
func (txmgr *LockBasedTxMgr) GetLastSavepoint() (*version.Height, error)
//调取newQueryExecutor(txmgr)
func (txmgr *LockBasedTxMgr) NewQueryExecutor() (ledger.QueryExecutor, error)
func (txmgr *LockBasedTxMgr) NewTxSimulator() (ledger.TxSimulator, error)
//验证Block，并从Block中获取写集加入批处理txmgr.batch
func (txmgr *LockBasedTxMgr) ValidateAndPrepare(block *common.Block, doMVCCValidation bool) error
func (txmgr *LockBasedTxMgr) Shutdown()
//执行txmgr.batch，
func (txmgr *LockBasedTxMgr) Commit() error
func (txmgr *LockBasedTxMgr) Rollback()
func (txmgr *LockBasedTxMgr) ShouldRecover(lastAvailableBlock uint64) ( bool, uint64, error)
func (txmgr *LockBasedTxMgr) CommitLostBlock(block *common.Block) error
//代码在core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/lockbased_txmgr.go
```
### 8.3、lockBasedQueryExecutor结构体及方法（实现ledger.QueryExecutor接口）
```go
type lockBasedQueryExecutor struct {
helper *queryHelper
id string
}
func newQueryExecutor(txmgr *LockBasedTxMgr) *lockBasedQueryExecutor
func (q *lockBasedQueryExecutor) GetState(ns string, key string) ([] byte, error)
func (q *lockBasedQueryExecutor) GetStateMultipleKeys(namespace string, keys [] string) ([][] byte, error)
func (q *lockBasedQueryExecutor) GetStateRangeScanIterator(namespace string, startKey string, endKey string) (ledger.ResultsIterator, error)
func (q *lockBasedQueryExecutor) ExecuteQuery(namespace, query string) (ledger.ResultsIterator, error)
func (q *lockBasedQueryExecutor) Done()
//代码在core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/lockbased_query_executer.go
```
### 8.4、queryHelper结构体及方法
queryHelper结构体及方法：
```go
type queryHelper struct {
txmgr *LockBasedTxMgr //LockBasedTxMgr
rwsetBuilder *rwsetutil.RWSetBuilder //读写集工具
itrs []*resultsItr
err error
doneInvoked bool //是否调用完成
}
//statedb中获取versionedValue，并加入rwsetBuilder的nsRWs.readMap中
func (h *queryHelper) getState(ns string, key string) ([] byte, error)
//statedb中获取多个versionedValue，并加入rwsetBuilder的nsRWs.readMap中
func (h *queryHelper) getStateMultipleKeys(namespace string, keys [] string) ([][] byte, error)
//构造resultsItr，并加入queryHelper.itrs
func (h *queryHelper) getStateRangeScanIterator(namespace string, startKey string, endKey string) (commonledger.ResultsIterator, error)
执行查询并构造queryResultsItr
func (h *queryHelper) executeQuery(namespace, query string) (commonledger.ResultsIterator, error)
//done
func (h *queryHelper) done()
func (h *queryHelper) checkDone()
//代码在core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/helper.go
```
resultsItr结构体及方法：
```go
type resultsItr struct {
ns string
endKey string
dbItr statedb.ResultsIterator
rwSetBuilder *rwsetutil.RWSetBuilder
rangeQueryInfo *kvrwset.RangeQueryInfo
rangeQueryResultsHelper *rwsetutil.RangeQueryResultsHelper
}
func newResultsItr(ns string, startKey string, endKey string, db statedb.VersionedDB, rwsetBuilder *rwsetutil.RWSetBuilder, enableHashing bool, maxDegree uint32) (*resultsItr, error)
func (itr *resultsItr) Next() (commonledger.QueryResult, error)
func (itr *resultsItr) updateRangeQueryInfo(queryResult statedb.QueryResult)
func (itr *resultsItr) Close()
//代码在core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/helper.go
```
