path: root/ethchain/block_chain.go

package ethchain

import (
    "bytes"
    "github.com/ethereum/eth-go/ethutil"
    "log"
    "math"
    "math/big"
)

type BlockChain struct {
    // The famous, the fabulous Mister GENESIIIIIIS (block)
    genesisBlock *Block
    // Last known total difficulty
    TD *big.Int

    LastBlockNumber uint64

    CurrentBlock  *Block
    LastBlockHash []byte
}

func NewBlockChain() *BlockChain {
    bc := &BlockChain{}
    bc.genesisBlock = NewBlockFromData(ethutil.Encode(Genesis))

    bc.setLastBlock()

    return bc
}

func (bc *BlockChain) Genesis() *Block {
    return bc.genesisBlock
}

func (bc *BlockChain) NewBlock(coinbase []byte, txs []*Transaction) *Block {
    var root interface{}
    var lastBlockTime int64
    hash := ZeroHash256

    if bc.CurrentBlock != nil {
        root = bc.CurrentBlock.State().Root
        hash = bc.LastBlockHash
        lastBlockTime = bc.CurrentBlock.Time
    }

    block := CreateBlock(
        root,
        hash,
        coinbase,
        ethutil.BigPow(2, 32),
        nil,
        "",
        txs)

    if bc.CurrentBlock != nil {
        var mul *big.Int
        if block.Time < lastBlockTime+42 {
            mul = big.NewInt(1)
        } else {
            mul = big.NewInt(-1)
        }

        diff := new(big.Int)
        diff.Add(diff, bc.CurrentBlock.Difficulty)
        diff.Div(diff, big.NewInt(1024))
        diff.Mul(diff, mul)
        diff.Add(diff, bc.CurrentBlock.Difficulty)
        block.Difficulty = diff
    }

    return block
}

func (bc *BlockChain) HasBlock(hash []byte) bool {
    data, _ := ethutil.Config.Db.Get(hash)
    return len(data) != 0
}

func (bc *BlockChain) GenesisBlock() *Block {
    return bc.genesisBlock
}

// Get chain return blocks from hash up to max in RLP format
func (bc *BlockChain) GetChainFromHash(hash []byte, max uint64) []interface{} {
    var chain []interface{}
    // Get the current hash to start with
    currentHash := bc.CurrentBlock.Hash()
    // Get the last number on the block chain
    lastNumber := bc.BlockInfo(bc.CurrentBlock).Number
    // Get the parents number
    parentNumber := bc.BlockInfoByHash(hash).Number
    // Get the min amount. We might not have max amount of blocks
    count := uint64(math.Min(float64(lastNumber-parentNumber), float64(max)))
    startNumber := parentNumber + count

    num := lastNumber
    for ; num > startNumber; currentHash = bc.GetBlock(currentHash).PrevHash {
        num--
    }
    for i := uint64(0); bytes.Compare(currentHash, hash) != 0 && num >= parentNumber && i < count; i++ {
        // Get the block of the chain
        block := bc.GetBlock(currentHash)
        currentHash = block.PrevHash

        chain = append(chain, block.RlpValue().Value)
        //chain = append([]interface{}{block.RlpValue().Value}, chain...)

        num--
    }

    return chain
}

func (bc *BlockChain) setLastBlock() {
    data, _ := ethutil.Config.Db.Get([]byte("LastBlock"))
    if len(data) != 0 {
        block := NewBlockFromBytes(data)
        info := bc.BlockInfo(block)
        bc.CurrentBlock = block
        bc.LastBlockHash = block.Hash()
        bc.LastBlockNumber = info.Number

        log.Printf("[CHAIN] Last known block height #%d\n", bc.LastBlockNumber)
    }

    // Set the last know difficulty (might be 0x0 as initial value, Genesis)
    bc.TD = ethutil.BigD(ethutil.Config.Db.LastKnownTD())
}

func (bc *BlockChain) SetTotalDifficulty(td *big.Int) {
    ethutil.Config.Db.Put([]byte("LastKnownTotalDifficulty"), td.Bytes())
    bc.TD = td
}

// Add a block to the chain and record addition information
func (bc *BlockChain) Add(block *Block) {
    bc.writeBlockInfo(block)

    // Prepare the genesis block
    bc.CurrentBlock = block
    bc.LastBlockHash = block.Hash()

    ethutil.Config.Db.Put(block.Hash(), block.RlpEncode())
}

func (bc *BlockChain) GetBlock(hash []byte) *Block {
    data, _ := ethutil.Config.Db.Get(hash)

    return NewBlockFromData(data)
}

func (bc *BlockChain) BlockInfoByHash(hash []byte) BlockInfo {
    bi := BlockInfo{}
    data, _ := ethutil.Config.Db.Get(append(hash, []byte("Info")...))
    bi.RlpDecode(data)

    return bi
}

func (bc *BlockChain) BlockInfo(block *Block) BlockInfo {
    bi := BlockInfo{}
    data, _ := ethutil.Config.Db.Get(append(block.Hash(), []byte("Info")...))
    bi.RlpDecode(data)

    return bi
}

// Unexported method for writing extra non-essential block info to the db
func (bc *BlockChain) writeBlockInfo(block *Block) {
    bc.LastBlockNumber++
    bi := BlockInfo{Number: bc.LastBlockNumber, Hash: block.Hash(), Parent: block.PrevHash}

    // For now we use the block hash with the words "info" appended as key
    ethutil.Config.Db.Put(append(block.Hash(), []byte("Info")...), bi.RlpEncode())
}

func (bc *BlockChain) Stop() {
    if bc.CurrentBlock != nil {
        ethutil.Config.Db.Put([]byte("LastBlock"), bc.CurrentBlock.RlpEncode())

        log.Println("[CHAIN] Stopped")
    }
}