go实现区块链[3]-遍历区块链与数据库持久化

新建blockchain.go

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package main

import (
"github.com/boltdb/bolt"
"log"
"fmt"
)

const dbFile = "blockchain.db"
const blockBucket = "blocks"
type Blockchain struct{
tip []byte //最近的一个区块的hash值
db * bolt.DB
}


func (bc * Blockchain) AddBlock(){
var lasthash []byte

err := bc.db.View(func(tx * bolt.Tx) error{
b:= tx.Bucket([]byte(blockBucket))
lasthash = b.Get([]byte("l"))
return nil
})
if err!=nil{
log.Panic(err)
}
newBlock := NewBlock(lasthash)


bc.db.Update(func(tx *bolt.Tx) error {
b:=tx.Bucket([]byte(blockBucket))
err:= b.Put(newBlock.Hash,newBlock.Serialize())
if err!=nil{
log.Panic(err)
}
err = b.Put([]byte("l"),newBlock.Hash)

if err!=nil{
log.Panic(err)
}
bc.tip = newBlock.Hash
return nil
})
}


func NewBlockchain() * Blockchain{
var tip []byte
db,err := bolt.Open(dbFile,0600,nil)
if err!=nil{
log.Panic(err)
}

err = db.Update(func(tx * bolt.Tx) error{

b:= tx.Bucket([]byte(blockBucket))

if b==nil{

fmt.Println("区块链不存在,创建一个新的区块链")

genesis := NewGensisBlock()
b,err:=tx.CreateBucket([]byte(blockBucket))
if err!=nil{
log.Panic(err)
}

err = b.Put(genesis.Hash,genesis.Serialize())
if err!=nil{
log.Panic(err)
}
err = b.Put([]byte("l"),genesis.Hash)
tip = genesis.Hash

}else{
tip = b.Get([]byte("l"))
}

return nil
})

if err!=nil{
log.Panic(err)
}

bc:=Blockchain{tip,db}
return &bc
}

增加newBlock的方法,根据前一个区块的hash创建区块:

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func NewBlock(prevBlockHash []byte) * Block{

block := &Block{
2,
prevBlockHash,
[]byte{},
[]byte{},
int32(time.Now().Unix()),
404454260,
0,
[]*Transation{},
}

pow := NewProofofWork(block)

nonce,hash := pow.Run()

block.Hash = hash
block.Nonce = nonce

return block
}