兄弟连区块链教程Fabric1.0源代码分析Chaincode（链码）体系总结，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。
# Fabric 1.0源代码笔记 之 Chaincode（链码）
## 1、Chaincode概述
Chaincode，即链码或智能合约，代码分布在protos/peer目录、core/chaincode和core/common/ccprovider目录，目录结构如下：
* protos/peer目录：
* chaincode.pb.go，ChaincodeDeploymentSpec、ChaincodeInvocationSpec结构体定义。
* core/chaincode目录：
* platforms目录，链码的编写语言平台实现，如golang或java。
* platforms.go，Platform接口定义，及部分工具函数。
* java目录，java语言平台实现。
* golang目录，golang语言平台实现。
* core/common/ccprovider目录：ccprovider相关实现。
## 2、protos相关结构体定义
### 2.1、ChaincodeDeploymentSpec结构体定义（用于Chaincode部署）
#### 2.1.1 ChaincodeDeploymentSpec结构体定义
```go
type ChaincodeDeploymentSpec struct {
ChaincodeSpec *ChaincodeSpec //ChaincodeSpec消息
EffectiveDate *google_protobuf1.Timestamp
CodePackage []byte //链码文件打包
ExecEnv ChaincodeDeploymentSpec_ExecutionEnvironment //链码执行环境，DOCKER或SYSTEM
}
type ChaincodeDeploymentSpec_ExecutionEnvironment int32
const (
ChaincodeDeploymentSpec_DOCKER ChaincodeDeploymentSpec_ExecutionEnvironment = 0
ChaincodeDeploymentSpec_SYSTEM ChaincodeDeploymentSpec_ExecutionEnvironment = 1
)
//代码在protos/peer/chaincode.pb.go
```
#### 2.1.2、ChaincodeSpec结构体定义
```go
type ChaincodeSpec struct {
Type ChaincodeSpec_Type //链码的编写语言，GOLANG、JAVA
ChaincodeId *ChaincodeID //ChaincodeId，链码路径、链码名称、链码版本
Input *ChaincodeInput //链码的具体执行参数信息
Timeout int32
}
type ChaincodeSpec_Type int32
const (
ChaincodeSpec_UNDEFINED ChaincodeSpec_Type = 0
ChaincodeSpec_GOLANG ChaincodeSpec_Type = 1
ChaincodeSpec_NODE ChaincodeSpec_Type = 2
ChaincodeSpec_CAR ChaincodeSpec_Type = 3
ChaincodeSpec_JAVA ChaincodeSpec_Type = 4
)
type ChaincodeID struct {
Path string
Name string
Version string
}
type ChaincodeInput struct { //链码的具体执行参数信息
Args [][]byte
}
//代码在protos/peer/chaincode.pb.go
```
### 2.2、ChaincodeInvocationSpec结构体定义
```go
type ChaincodeInvocationSpec struct {
ChaincodeSpec *ChaincodeSpec //参考本文2.2
IdGenerationAlg string
}
//代码在protos/peer/chaincode.pb.go
```
## 3、ccprovider目录相关实现
### 3.1、ChaincodeData结构体
```go
type ChaincodeData struct {
Name string
Version string
Escc string
Vscc string
Policy []byte //chaincode 实例的背书策略
Data []byte
Id []byte
InstantiationPolicy []byte //实例化策略
}
//获取ChaincodeData，优先从缓存中读取
func GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error)
//代码在core/common/ccprovider/ccprovider.go
```
func GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error)代码如下：
```go
var ccInfoFSProvider = &CCInfoFSImpl{}
var ccInfoCache = NewCCInfoCache(ccInfoFSProvider)
func GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error) {
//./peer/node/start.go: ccprovider.EnableCCInfoCache()
//如果启用ccInfoCache，优先从缓存中读取ChaincodeData
if ccInfoCacheEnabled {
return ccInfoCache.GetChaincodeData(ccname, ccversion)
}
ccpack, err := ccInfoFSProvider.GetChaincode(ccname, ccversion)
return ccpack.GetChaincodeData(), nil
}
//代码在core/common/ccprovider/ccprovider.go
```
### 3.2、ccInfoCacheImpl结构体
```go
type ccInfoCacheImpl struct {
sync.RWMutex
cache map[string]*ChaincodeData //ChaincodeData
cacheSupport CCCacheSupport
}
//构造ccInfoCacheImpl
func NewCCInfoCache(cs CCCacheSupport) *ccInfoCacheImpl
//获取ChaincodeData，优先从c.cache中获取，如果c.cache中没有，则从c.cacheSupport（即CCInfoFSImpl）中获取并写入c.cache
func (c *ccInfoCacheImpl) GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error)
//代码在core/common/ccprovider/ccinfocache.go
```
func (c *ccInfoCacheImpl) GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error) 代码如下：
```go
func (c *ccInfoCacheImpl) GetChaincodeData(ccname string, ccversion string) (*ChaincodeData, error) {
key := ccname + "/" + ccversion
c.RLock()
ccdata, in := c.cache[key] //优先从c.cache中获取
c.RUnlock()
if !in { //如果c.cache中没有
var err error
//从c.cacheSupport中获取
ccpack, err := c.cacheSupport.GetChaincode(ccname, ccversion)
c.Lock()
//并写入c.cache
ccdata = ccpack.GetChaincodeData()
c.cache[key] = ccdata
c.Unlock()
}
return ccdata, nil
}
//代码在core/common/ccprovider/ccinfocache.go
```
### 3.3、CCCacheSupport接口定义及实现
#### 3.3.1、CCCacheSupport接口定义
```go
type CCCacheSupport interface {
//获取Chaincode包
GetChaincode(ccname string, ccversion string) (CCPackage, error)
}
//代码在core/common/ccprovider/ccprovider.go
```
#### 3.3.2、CCCacheSupport接口实现（即CCInfoFSImpl结构体）
```go
type CCInfoFSImpl struct{}
//从文件系统中读取并构造CDSPackage或SignedCDSPackage
func (*CCInfoFSImpl) GetChaincode(ccname string, ccversion string) (CCPackage, error) {
cccdspack := &CDSPackage{}
_, _, err := cccdspack.InitFromFS(ccname, ccversion)
if err != nil {
//try signed CDS
ccscdspack := &SignedCDSPackage{}
_, _, err = ccscdspack.InitFromFS(ccname, ccversion)
if err != nil {
return nil, err
}
return ccscdspack, nil
}
return cccdspack, nil
}
//将ChaincodeDeploymentSpec序列化后写入文件系统
func (*CCInfoFSImpl) PutChaincode(depSpec *pb.ChaincodeDeploymentSpec) (CCPackage, error) {
buf, err := proto.Marshal(depSpec)
cccdspack := &CDSPackage{}
_, err := cccdspack.InitFromBuffer(buf)
err = cccdspack.PutChaincodeToFS()
}
//代码在core/common/ccprovider/ccprovider.go
```
### 3.4、CCPackage接口定义及实现
#### 3.4.1、CCPackage接口定义
```go
type CCPackage interface {
//从字节初始化包
InitFromBuffer(buf []byte) (*ChaincodeData, error)
//从文件系统初始化包
InitFromFS(ccname string, ccversion string) ([]byte, *pb.ChaincodeDeploymentSpec, error)
//将chaincode包写入文件系统
PutChaincodeToFS() error
//从包中获取ChaincodeDeploymentSpec
GetDepSpec() *pb.ChaincodeDeploymentSpec
//从包中获取序列化的ChaincodeDeploymentSpec
GetDepSpecBytes() []byte
//校验ChaincodeData
ValidateCC(ccdata *ChaincodeData) error
//包转换为proto.Message
GetPackageObject() proto.Message
//获取ChaincodeData
GetChaincodeData() *ChaincodeData
//基于包计算获取chaincode Id
GetId() []byte
}
//代码在core/common/ccprovider/ccprovider.go
```
#### 3.4.2、CCPackage接口实现（CDSPackage）
```go
type CDSData struct {
CodeHash []byte //ChaincodeDeploymentSpec.CodePackage哈希
MetaDataHash []byte //ChaincodeSpec.ChaincodeId.Name和ChaincodeSpec.ChaincodeId.Version哈希
}
type CDSPackage struct {
buf []byte //ChaincodeDeploymentSpec哈希
depSpec *pb.ChaincodeDeploymentSpec //ChaincodeDeploymentSpec
data *CDSData
datab []byte
id []byte //id为CDSData.CodeHash和CDSData.MetaDataHash求哈希
}
//获取ccpack.id
func (ccpack *CDSPackage) GetId() []byte
//获取ccpack.depSpec
func (ccpack *CDSPackage) GetDepSpec() *pb.ChaincodeDeploymentSpec
//获取ccpack.buf，即ChaincodeDeploymentSpec哈希
func (ccpack *CDSPackage) GetDepSpecBytes() []byte
//获取ccpack.depSpec
func (ccpack *CDSPackage) GetPackageObject() proto.Message
//构造ChaincodeData
func (ccpack *CDSPackage) GetChaincodeData() *ChaincodeData
//获取ChaincodeDeploymentSpec哈希、CDSData、id
func (ccpack *CDSPackage) getCDSData(cds *pb.ChaincodeDeploymentSpec) ([]byte, []byte, *CDSData, error)
//校验CDSPackage和ChaincodeData
func (ccpack *CDSPackage) ValidateCC(ccdata *ChaincodeData) error
//[]byte反序列化为ChaincodeDeploymentSpec，构造CDSPackage，进而构造ChaincodeData
func (ccpack *CDSPackage) InitFromBuffer(buf []byte) (*ChaincodeData, error)
//从文件系统中获取ChaincodeData，即buf, err := GetChaincodePackage(ccname, ccversion)和_, err = ccpack.InitFromBuffer(buf)
func (ccpack *CDSPackage) InitFromFS(ccname string, ccversion string) ([]byte, *pb.ChaincodeDeploymentSpec, error)
//ccpack.buf写入文件，文件名为/var/hyperledger/production/chaincodes/Name.Version
func (ccpack *CDSPackage) PutChaincodeToFS() error
//代码在core/common/ccprovider/cdspackage.go
```
### 3.5、CCContext结构体
```go
type CCContext struct { //ChaincodeD上下文
ChainID string
Name string
Version string
TxID string
Syscc bool
SignedProposal *pb.SignedProposal
Proposal *pb.Proposal
canonicalName string
}
//构造CCContext
func NewCCContext(cid, name, version, txid string, syscc bool, signedProp *pb.SignedProposal, prop *pb.Proposal) *CCContext
//name + ":" + version
func (cccid *CCContext) GetCanonicalName() string
//代码在core/common/ccprovider/ccprovider.go
```
## 4、chaincode目录相关实现
### 4.1、ChaincodeProviderFactory接口定义及实现
#### 4.1.1、ChaincodeProviderFactory接口定义
```go
type ChaincodeProviderFactory interface {
//构造ChaincodeProvider实例
NewChaincodeProvider() ChaincodeProvider
}
func RegisterChaincodeProviderFactory(ccfact ChaincodeProviderFactory) {
ccFactory = ccfact
}
func GetChaincodeProvider() ChaincodeProvider {
return ccFactory.NewChaincodeProvider()
}
//代码在core/common/ccprovider/ccprovider.go
```
#### 4.1.2、ChaincodeProviderFactory接口实现
```go
type ccProviderFactory struct {
}
func (c *ccProviderFactory) NewChaincodeProvider() ccprovider.ChaincodeProvider {
return &ccProviderImpl{}
}
func init() {
ccprovider.RegisterChaincodeProviderFactory(&ccProviderFactory{})
}
//代码在core/chaincode/ccproviderimpl.go
```
### 4.2、ChaincodeProvider接口定义及实现
#### 4.2.1、ChaincodeProvider接口定义
```go
type ChaincodeProvider interface {
GetContext(ledger ledger.PeerLedger) (context.Context, error)
GetCCContext(cid, name, version, txid string, syscc bool, signedProp *pb.SignedProposal, prop *pb.Proposal) interface{}
GetCCValidationInfoFromLSCC(ctxt context.Context, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, chainID string, chaincodeID string) (string, []byte, error)
ExecuteChaincode(ctxt context.Context, cccid interface{}, args [][]byte) (*pb.Response, *pb.ChaincodeEvent, error)
Execute(ctxt context.Context, cccid interface{}, spec interface{}) (*pb.Response, *pb.ChaincodeEvent, error)
ExecuteWithErrorFilter(ctxt context.Context, cccid interface{}, spec interface{}) ([]byte, *pb.ChaincodeEvent, error)
Stop(ctxt context.Context, cccid interface{}, spec *pb.ChaincodeDeploymentSpec) error
ReleaseContext()
}
//代码在core/common/ccprovider/ccprovider.go
```
#### 4.2.2、ChaincodeProvider接口实现
```go
type ccProviderImpl struct {
txsim ledger.TxSimulator //交易模拟器
}
type ccProviderContextImpl struct {
ctx *ccprovider.CCContext
}
//获取context.Context，添加TXSimulatorKey绑定c.txsim
func (c *ccProviderImpl) GetContext(ledger ledger.PeerLedger) (context.Context, error)
//构造CCContext，并构造ccProviderContextImpl
func (c *ccProviderImpl) GetCCContext(cid, name, version, txid string, syscc bool, signedProp *pb.SignedProposal, prop *pb.Proposal) interface{}
//调用GetChaincodeDataFromLSCC(ctxt, txid, signedProp, prop, chainID, chaincodeID)获取ChaincodeData中Vscc和Policy
func (c *ccProviderImpl) GetCCValidationInfoFromLSCC(ctxt context.Context, txid string, signedProp *pb.SignedProposal, prop *pb.Proposal, chainID string, chaincodeID string) (string, []byte, error)
//调用ExecuteChaincode(ctxt, cccid.(*ccProviderContextImpl).ctx, args)执行上下文中指定的链码
func (c *ccProviderImpl) ExecuteChaincode(ctxt context.Context, cccid interface{}, args [][]byte) (*pb.Response, *pb.ChaincodeEvent, error)
//调用Execute(ctxt, cccid.(*ccProviderContextImpl).ctx, spec)
func (c *ccProviderImpl) Execute(ctxt context.Context, cccid interface{}, spec interface{}) (*pb.Response, *pb.ChaincodeEvent, error)
//调用ExecuteWithErrorFilter(ctxt, cccid.(*ccProviderContextImpl).ctx, spec)
func (c *ccProviderImpl) ExecuteWithErrorFilter(ctxt context.Context, cccid interface{}, spec interface{}) ([]byte, *pb.ChaincodeEvent, error)
//调用theChaincodeSupport.Stop(ctxt, cccid.(*ccProviderContextImpl).ctx, spec)
func (c *ccProviderImpl) Stop(ctxt context.Context, cccid interface{}, spec *pb.ChaincodeDeploymentSpec) error
//调用c.txsim.Done()
func (c *ccProviderImpl) ReleaseContext() {
//代码在core/chaincode/ccproviderimpl.go
```
### 4.3、ChaincodeSupport结构体
ChaincodeSupport更详细内容，参考：Fabric 1.0源代码笔记 之 Chaincode（链码） #ChaincodeSupport（链码支持服务端）
### 4.4、ExecuteChaincode函数（执行链码）
执行链码上下文中指定的链码。
```go
func ExecuteChaincode(ctxt context.Context, cccid *ccprovider.CCContext, args [][]byte) (*pb.Response, *pb.ChaincodeEvent, error) {
var spec *pb.ChaincodeInvocationSpec
var err error
var res *pb.Response
var ccevent *pb.ChaincodeEvent
spec, err = createCIS(cccid.Name, args) //构造ChaincodeInvocationSpec
res, ccevent, err = Execute(ctxt, cccid, spec)
return res, ccevent, err
}
//代码在core/chaincode/chaincodeexec.go
```
res, ccevent, err = Execute(ctxt, cccid, spec)代码如下：
```go
func Execute(ctxt context.Context, cccid *ccprovider.CCContext, spec interface{}) (*pb.Response, *pb.ChaincodeEvent, error) {
var err error
var cds *pb.ChaincodeDeploymentSpec
var ci *pb.ChaincodeInvocationSpec
cctyp := pb.ChaincodeMessage_INIT //初始化
if cds, _ = spec.(*pb.ChaincodeDeploymentSpec); cds == nil { //优先判断ChaincodeDeploymentSpec
if ci, _ = spec.(*pb.ChaincodeInvocationSpec); ci == nil { //其次判断ChaincodeInvocationSpec
panic("Execute should be called with deployment or invocation spec")
}
cctyp = pb.ChaincodeMessage_TRANSACTION //交易
}
_, cMsg, err := theChaincodeSupport.Launch(ctxt, cccid, spec)
var ccMsg *pb.ChaincodeMessage
ccMsg, err = createCCMessage(cctyp, cccid.TxID, cMsg)
resp, err := theChaincodeSupport.Execute(ctxt, cccid, ccMsg, theChaincodeSupport.executetimeout)
if resp.ChaincodeEvent != nil {
resp.ChaincodeEvent.ChaincodeId = cccid.Name
resp.ChaincodeEvent.TxId = cccid.TxID
}
if resp.Type == pb.ChaincodeMessage_COMPLETED {
res := &pb.Response{}
unmarshalErr := proto.Unmarshal(resp.Payload, res)
return res, resp.ChaincodeEvent, nil
}
}
//代码在core/chaincode
```
## 5、platforms（链码的编写语言平台）
platforms更详细内容，参考：Fabric 1.0源代码笔记 之 Chaincode（链码） #platforms（链码语言平台）欢迎继续关注兄弟连区块链教程分享!
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