Fabric 1.0源代码笔记 之 Orderer #ledger(Orderer Ledger)
1、Orderer Ledger概述
Orderer Ledger代码分布在orderer/ledger目录下,目录结构如下:
- orderer/ledger目录:
ledger.go,Factory、Iterator、Reader、Writer、ReadWriter等接口定义。
util.go,Orderer Ledger工具函数,及NotFoundErrorIterator结构体定义。
file目录,file类型ledger实现。
json目录,json类型ledger实现。
* ram目录,内存类型ledger实现。
2、接口定义
Factory接口定义:
type Factory interface {
//按chainID获取已存在的ledger,如不存在则创建
GetOrCreate(chainID string) (ReadWriter, error)
//获取ChainID列表
ChainIDs() []string
//关闭并释放所有资源
Close()
}
//代码在orderer/ledger/ledger.go
ReadWriter接口定义:
type Reader interface {
//按起始块号获取迭代器
Iterator(startType *ab.SeekPosition) (Iterator, uint64)
//获取ledger高度(即块数)
Height() uint64
}
type Writer interface {
//ledger向追加新块
Append(block *cb.Block) error
}
type ReadWriter interface {
Reader //嵌入Reader
Writer //嵌入Writer
}
type Iterator interface {
//获取下一个可用的块
Next() (*cb.Block, cb.Status)
//获取可用的通道
ReadyChan() <-chan struct{}
}
//代码在orderer/ledger/ledger.go
3、file类型ledger实现
3.1、fileLedgerFactory结构体及方法(实现Factory接口)
type fileLedgerFactory struct {
blkstorageProvider blkstorage.BlockStoreProvider //blkstorage
ledgers map[string]ledger.ReadWriter //多链
mutex sync.Mutex
}
//从ledgers中查找,如找到则返回,否则创建Ledger(即blkstorage)并构造fileLedger
func (flf *fileLedgerFactory) GetOrCreate(chainID string) (ledger.ReadWriter, error)
//获取已存在的Ledger列表,调取flf.blkstorageProvider.List()
func (flf *fileLedgerFactory) ChainIDs() []string
//关闭并释放资源flf.blkstorageProvider.Close()
func (flf *fileLedgerFactory) Close()
//构造fileLedgerFactory
func New(directory string) ledger.Factory
//代码在orderer/ledger/file/factory.go
blkstorage更详细内容,可参考:Fabric 1.0源代码笔记 之 Ledger #blkstorage(block文件存储)
3.2、fileLedger结构体及方法(实现ReadWriter接口)
type fileLedger struct {
blockStore blkstorage.BlockStore //blkstorage
signal chan struct{}
}
//按起始块号获取迭代器
func (fl *fileLedger) Iterator(startPosition *ab.SeekPosition) (ledger.Iterator, uint64)
//获取ledger高度(即块数)
func (fl *fileLedger) Height() uint64
//ledger向追加新块
func (fl *fileLedger) Append(block *cb.Block) error
//代码在orderer/ledger/file/impl.go
3.3、fileLedgerIterator结构体及方法(实现Iterator接口)
type fileLedgerIterator struct {
ledger *fileLedger
blockNumber uint64 //当前已迭代的块号
}
//获取下一个可用的块,如果没有可用的块则阻止
func (i *fileLedgerIterator) Next() (*cb.Block, cb.Status)
//获取可用的通道,如果块不可用返回signal,否则返回closedChan
func (i *fileLedgerIterator) ReadyChan() <-chan struct{}
//代码在orderer/ledger/file/impl.go
4、Orderer Ledger工具函数
//创建块
func CreateNextBlock(rl Reader, messages []*cb.Envelope) *cb.Block
func GetBlock(rl Reader, index uint64) *cb.Block
//地址在orderer/ledger/util.go
func CreateNextBlock(rl Reader, messages []cb.Envelope) cb.Block代码如下:
func CreateNextBlock(rl Reader, messages []*cb.Envelope) *cb.Block {
var nextBlockNumber uint64
var previousBlockHash []byte
if rl.Height() > 0 {
it, _ := rl.Iterator(&ab.SeekPosition{
Type: &ab.SeekPosition_Newest{
&ab.SeekNewest{},
},
})
<-it.ReadyChan()
block, status := it.Next() //获取前一个最新的块
nextBlockNumber = block.Header.Number + 1
previousBlockHash = block.Header.Hash() //前一个最新的块的哈希
}
data := &cb.BlockData{
Data: make([][]byte, len(messages)),
}
var err error
for i, msg := range messages {
data.Data[i], err = proto.Marshal(msg) //逐一填充数据
}
block := cb.NewBlock(nextBlockNumber, previousBlockHash)
block.Header.DataHash = data.Hash()
block.Data = data
return block
}
//地址在orderer/ledger/util.go