区块链教程Fabric1.0源代码分析Orderer multichain多链支持包

1、multichain概述

multichain代码集中在orderer/multichain目录下，目录结构如下：

• manager.go，Manager接口定义及实现。
• chainsupport.go，ChainSupport接口定义及实现。
• systemchain.go，system chain。

2、Manager接口定义及实现

2.1、Manager接口定义

用于链的创建和访问。

type Manager interface {
????//获取ChainSupport，以及判断链是否存在
????GetChain(chainID string) (ChainSupport, bool)
????//获取系统通道的通道ID
????SystemChannelID() string
????//支持通道创建请求
????NewChannelConfig(envConfigUpdate *cb.Envelope) (configtxapi.Manager, error)
}
//代码在orderer/multichain/manager.go

2.2、Manager接口实现

Manager接口实现，即multiLedger结构体及方法。

type multiLedger struct {
????chains          map[string]*chainSupport
????consenters      map[string]Consenter
????ledgerFactory   ledger.Factory
????signer          crypto.LocalSigner
????systemChannelID string
????systemChannel   *chainSupport
}

type configResources struct {
????configtxapi.Manager
}

type ledgerResources struct {
????*configResources
????ledger ledger.ReadWriter
}
//代码在orderer/multichain/manager.go

涉及方法如下：

func (cr *configResources) SharedConfig() config.Orderer
//获取配置交易Envelope
func getConfigTx(reader ledger.Reader) *cb.Envelope
//构造multiLedger
func NewManagerImpl(ledgerFactory ledger.Factory, consenters map[string]Consenter, signer crypto.LocalSigner) Manager
//获取系统链ID
func (ml *multiLedger) SystemChannelID() string
//按chainID获取ChainSupport
func (ml *multiLedger) GetChain(chainID string) (ChainSupport, bool)
//构造ledgerResources
func (ml *multiLedger) newLedgerResources(configTx *cb.Envelope) *ledgerResources
//创建新链
func (ml *multiLedger) newChain(configtx *cb.Envelope)
//通道或链的个数
func (ml *multiLedger) channelsCount() int
//支持创建新的通道
func (ml *multiLedger) NewChannelConfig(envConfigUpdate *cb.Envelope) (configtxapi.Manager, error)
//代码在orderer/multichain/manager.go

func NewManagerImpl(ledgerFactory ledger.Factory, consenters map[string]Consenter, signer crypto.LocalSigner) Manager代码如下：

func NewManagerImpl(ledgerFactory ledger.Factory, consenters map[string]Consenter, signer crypto.LocalSigner) Manager {
????ml := &multiLedger{
????????chains:        make(map[string]*chainSupport),
????????ledgerFactory: ledgerFactory,
????????consenters:    consenters,
????????signer:        signer,
????}

????existingChains := ledgerFactory.ChainIDs()
????for _, chainID := range existingChains {
????????rl, err := ledgerFactory.GetOrCreate(chainID)
????????configTx := getConfigTx(rl)
????????ledgerResources := ml.newLedgerResources(configTx)
????????chainID := ledgerResources.ChainID()

????????if _, ok := ledgerResources.ConsortiumsConfig(); ok { //系统链
????????????chain := newChainSupport(createSystemChainFilters(ml, ledgerResources), ledgerResources, consenters, signer)
????????????ml.chains[chainID] = chain
????????????ml.systemChannelID = chainID
????????????ml.systemChannel = chain
????????????defer chain.start()
????????} else { //普通链
????????????chain := newChainSupport(createStandardFilters(ledgerResources), ledgerResources, consenters, signer)
????????????ml.chains[chainID] = chain
????????????chain.start()
????????}
????}
????return ml
}
//代码在orderer/multichain/manager.go

3、ChainSupport接口定义及实现

3.1、ChainSupport接口定义

type ChainSupport interface {
????PolicyManager() policies.Manager //策略管理
????Reader() ledger.Reader
????Errored() <-chan struct{}
????broadcast.Support
????ConsenterSupport //嵌入ConsenterSupport接口
????Sequence() uint64
????//支持通道更新
????ProposeConfigUpdate(env *cb.Envelope) (*cb.ConfigEnvelope, error)
}

type ConsenterSupport interface {
????crypto.LocalSigner
????BlockCutter() blockcutter.Receiver
????SharedConfig() config.Orderer
????CreateNextBlock(messages []*cb.Envelope) *cb.Block
????WriteBlock(block *cb.Block, committers []filter.Committer, encodedMetadataValue []byte) *cb.Block
????ChainID() string
????Height() uint64
}

type Consenter interface { //定义支持排序机制
????HandleChain(support ConsenterSupport, metadata *cb.Metadata) (Chain, error)
}

type Chain interface {
????//接受消息
????Enqueue(env *cb.Envelope) bool
????Errored() <-chan struct{}
????Start() //开始
????Halt() //挂起
}
//代码在orderer/multichain/chainsupport.go

3.2、ChainSupport和ConsenterSupport接口实现

ChainSupport接口实现，即chainSupport结构体及方法。

type chainSupport struct {
????*ledgerResources
????chain         Chain
????cutter        blockcutter.Receiver
????filters       *filter.RuleSet
????signer        crypto.LocalSigner
????lastConfig    uint64
????lastConfigSeq uint64
}
//代码在orderer/multichain/chainsupport.go

涉及方法如下：

//构造chainSupport
func newChainSupport(filters *filter.RuleSet,ledgerResources *ledgerResources,consenters map[string]Consenter,signer crypto.LocalSigner,) *chainSupport
func createStandardFilters(ledgerResources *ledgerResources) *filter.RuleSet
func createSystemChainFilters(ml *multiLedger, ledgerResources *ledgerResources) *filter.RuleSet
func (cs *chainSupport) start()
func (cs *chainSupport) NewSignatureHeader() (*cb.SignatureHeader, error)
func (cs *chainSupport) Sign(message []byte) ([]byte, error)
func (cs *chainSupport) Filters() *filter.RuleSet
func (cs *chainSupport) BlockCutter() blockcutter.Receiver
func (cs *chainSupport) Reader() ledger.Reader
func (cs *chainSupport) Enqueue(env *cb.Envelope) bool
func (cs *chainSupport) Errored() <-chan struct{}
//创建块，调取ledger.CreateNextBlock(cs.ledger, messages)
func (cs *chainSupport) CreateNextBlock(messages []*cb.Envelope) *cb.Block
func (cs *chainSupport) addBlockSignature(block *cb.Block)
func (cs *chainSupport) addLastConfigSignature(block *cb.Block)
//写入块
func (cs *chainSupport) WriteBlock(block *cb.Block, committers []filter.Committer, encodedMetadataValue []byte) *cb.Block 
func (cs *chainSupport) Height() uint64
//代码在orderer/multichain/chainsupport.go

func (cs chainSupport) WriteBlock(block cb.Block, committers []filter.Committer, encodedMetadataValue []byte) *cb.Block 代码如下：

func (cs *chainSupport) WriteBlock(block *cb.Block, committers []filter.Committer, encodedMetadataValue []byte) *cb.Block {
????for _, committer := range committers {
????????committer.Commit()
????}
????cs.addBlockSignature(block)
????cs.addLastConfigSignature(block)
????err := cs.ledger.Append(block)//账本追加块
????return block
}
//代码在orderer/multichain/chainsupport.go

区块链教程Fabric1.0源代码分析Orderer multichain多链支持包

原文：http://blog.51cto.com/14041296/2312259