path: root/core/chain_manager.go

package core

import (
    "bytes"
    "fmt"
    "math/big"
    "sync"

    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/ethutil"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/state"
)

var chainlogger = logger.NewLogger("CHAIN")

type ChainEvent struct {
    Block *types.Block
    Td    *big.Int
}

type StateQuery interface {
    GetAccount(addr []byte) *state.StateObject
}

func CalcDifficulty(block, parent *types.Block) *big.Int {
    diff := new(big.Int)

    adjust := new(big.Int).Rsh(parent.Difficulty(), 10)
    if block.Time() >= parent.Time()+8 {
        diff.Sub(parent.Difficulty(), adjust)
    } else {
        diff.Add(parent.Difficulty(), adjust)
    }

    return diff
}

func CalculateTD(block, parent *types.Block) *big.Int {
    uncleDiff := new(big.Int)
    for _, uncle := range block.Uncles() {
        uncleDiff = uncleDiff.Add(uncleDiff, uncle.Difficulty)
    }

    // TD(genesis_block) = 0 and TD(B) = TD(B.parent) + sum(u.difficulty for u in B.uncles) + B.difficulty
    td := new(big.Int)
    td = td.Add(parent.Td, uncleDiff)
    td = td.Add(td, block.Header().Difficulty)

    return td
}

func CalcGasLimit(parent, block *types.Block) *big.Int {
    if block.Number().Cmp(big.NewInt(0)) == 0 {
        return ethutil.BigPow(10, 6)
    }

    // ((1024-1) * parent.gasLimit + (gasUsed * 6 / 5)) / 1024

    previous := new(big.Int).Mul(big.NewInt(1024-1), parent.GasLimit())
    current := new(big.Rat).Mul(new(big.Rat).SetInt(parent.GasUsed()), big.NewRat(6, 5))
    curInt := new(big.Int).Div(current.Num(), current.Denom())

    result := new(big.Int).Add(previous, curInt)
    result.Div(result, big.NewInt(1024))

    min := big.NewInt(125000)

    return ethutil.BigMax(min, result)
}

type ChainManager struct {
    //eth          EthManager
    db           ethutil.Database
    processor    types.BlockProcessor
    eventMux     *event.TypeMux
    genesisBlock *types.Block
    // Last known total difficulty
    mu              sync.RWMutex
    td              *big.Int
    lastBlockNumber uint64
    currentBlock    *types.Block
    lastBlockHash   []byte

    transState *state.StateDB
}

func (self *ChainManager) Td() *big.Int {
    self.mu.RLock()
    defer self.mu.RUnlock()

    return self.td
}

func (self *ChainManager) LastBlockNumber() uint64 {
    self.mu.RLock()
    defer self.mu.RUnlock()

    return self.lastBlockNumber
}

func (self *ChainManager) LastBlockHash() []byte {
    self.mu.RLock()
    defer self.mu.RUnlock()

    return self.lastBlockHash
}

func (self *ChainManager) CurrentBlock() *types.Block {
    self.mu.RLock()
    defer self.mu.RUnlock()

    return self.currentBlock
}

func NewChainManager(db ethutil.Database, mux *event.TypeMux) *ChainManager {
    bc := &ChainManager{db: db, genesisBlock: GenesisBlock(db), eventMux: mux}
    bc.setLastBlock()
    bc.transState = bc.State().Copy()

    return bc
}

func (self *ChainManager) Status() (td *big.Int, currentBlock []byte, genesisBlock []byte) {
    self.mu.RLock()
    defer self.mu.RUnlock()

    return self.td, self.currentBlock.Hash(), self.Genesis().Hash()
}

func (self *ChainManager) SetProcessor(proc types.BlockProcessor) {
    self.processor = proc
}

func (self *ChainManager) State() *state.StateDB {
    return state.New(self.CurrentBlock().Root(), self.db)
}

func (self *ChainManager) TransState() *state.StateDB {
    return self.transState
}

func (bc *ChainManager) setLastBlock() {
    data, _ := bc.db.Get([]byte("LastBlock"))
    if len(data) != 0 {
        var block types.Block
        rlp.Decode(bytes.NewReader(data), &block)
        bc.currentBlock = &block
        bc.lastBlockHash = block.Hash()
        bc.lastBlockNumber = block.Header().Number.Uint64()

        // Set the last know difficulty (might be 0x0 as initial value, Genesis)
        bc.td = ethutil.BigD(bc.db.LastKnownTD())
    } else {
        bc.Reset()
    }

    chainlogger.Infof("Last block (#%d) %x TD=%v\n", bc.lastBlockNumber, bc.currentBlock.Hash(), bc.td)
}

// Block creation & chain handling
func (bc *ChainManager) NewBlock(coinbase []byte) *types.Block {
    bc.mu.RLock()
    defer bc.mu.RUnlock()

    var root []byte
    parentHash := ZeroHash256

    if bc.currentBlock != nil {
        root = bc.currentBlock.Header().Root
        parentHash = bc.lastBlockHash
    }

    block := types.NewBlock(
        parentHash,
        coinbase,
        root,
        ethutil.BigPow(2, 32),
        nil,
        "")
    block.SetUncles(nil)
    block.SetTransactions(nil)
    block.SetReceipts(nil)

    parent := bc.currentBlock
    if parent != nil {
        header := block.Header()
        header.Difficulty = CalcDifficulty(block, parent)
        header.Number = new(big.Int).Add(parent.Header().Number, ethutil.Big1)
        header.GasLimit = CalcGasLimit(parent, block)

    }

    return block
}

func (bc *ChainManager) Reset() {
    bc.mu.Lock()
    defer bc.mu.Unlock()

    for block := bc.currentBlock; block != nil; block = bc.GetBlock(block.Header().ParentHash) {
        bc.db.Delete(block.Hash())
    }

    // Prepare the genesis block
    bc.write(bc.genesisBlock)
    bc.insert(bc.genesisBlock)
    bc.currentBlock = bc.genesisBlock

    bc.setTotalDifficulty(ethutil.Big("0"))
}

func (self *ChainManager) Export() []byte {
    self.mu.RLock()
    defer self.mu.RUnlock()

    chainlogger.Infof("exporting %v blocks...\n", self.currentBlock.Header().Number)

    blocks := make([]*types.Block, int(self.currentBlock.NumberU64())+1)
    for block := self.currentBlock; block != nil; block = self.GetBlock(block.Header().ParentHash) {
        blocks[block.NumberU64()] = block
    }

    return ethutil.Encode(blocks)
}

func (bc *ChainManager) insert(block *types.Block) {
    encodedBlock := ethutil.Encode(block)
    bc.db.Put([]byte("LastBlock"), encodedBlock)
    bc.currentBlock = block
    bc.lastBlockHash = block.Hash()
}

func (bc *ChainManager) write(block *types.Block) {
    bc.writeBlockInfo(block)

    encodedBlock := ethutil.Encode(block.RlpDataForStorage())
    bc.db.Put(block.Hash(), encodedBlock)
}

// Accessors
func (bc *ChainManager) Genesis() *types.Block {
    return bc.genesisBlock
}

// Block fetching methods
func (bc *ChainManager) HasBlock(hash []byte) bool {
    data, _ := bc.db.Get(hash)
    return len(data) != 0
}

func (self *ChainManager) GetBlockHashesFromHash(hash []byte, max uint64) (chain [][]byte) {
    block := self.GetBlock(hash)
    if block == nil {
        return
    }

    // XXX Could be optimised by using a different database which only holds hashes (i.e., linked list)
    for i := uint64(0); i < max; i++ {
        parentHash := block.Header().ParentHash
        block = self.GetBlock(parentHash)
        if block == nil {
            chainlogger.Infof("GetBlockHashesFromHash Parent UNKNOWN %x\n", parentHash)
            break
        }

        chain = append(chain, block.Hash())
        if block.Header().Number.Cmp(ethutil.Big0) <= 0 {
            break
        }
    }

    return
}

func (self *ChainManager) GetBlock(hash []byte) *types.Block {
    data, _ := self.db.Get(hash)
    if len(data) == 0 {
        return nil
    }
    var block types.Block
    if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
        fmt.Println(err)
        return nil
    }

    return &block
}

func (self *ChainManager) GetUnclesInChain(block *types.Block, length int) (uncles []*types.Header) {
    for i := 0; block != nil && i < length; i++ {
        uncles = append(uncles, block.Uncles()...)
        block = self.GetBlock(block.ParentHash())
    }

    return
}

func (self *ChainManager) GetAncestors(block *types.Block, length int) (blocks []*types.Block) {
    for i := 0; i < length; i++ {
        block = self.GetBlock(block.ParentHash())
        if block == nil {
            break
        }

        blocks = append(blocks, block)
    }

    return
}

func (self *ChainManager) GetBlockByNumber(num uint64) *types.Block {
    self.mu.RLock()
    defer self.mu.RUnlock()

    var block *types.Block

    if num <= self.currentBlock.Number().Uint64() {
        block = self.currentBlock
        for ; block != nil; block = self.GetBlock(block.Header().ParentHash) {
            if block.Header().Number.Uint64() == num {
                break
            }
        }
    }

    return block
}

func (bc *ChainManager) setTotalDifficulty(td *big.Int) {
    bc.db.Put([]byte("LTD"), td.Bytes())
    bc.td = td
}

func (self *ChainManager) CalcTotalDiff(block *types.Block) (*big.Int, error) {
    parent := self.GetBlock(block.Header().ParentHash)
    if parent == nil {
        return nil, fmt.Errorf("Unable to calculate total diff without known parent %x", block.Header().ParentHash)
    }

    parentTd := parent.Td

    uncleDiff := new(big.Int)
    for _, uncle := range block.Uncles() {
        uncleDiff = uncleDiff.Add(uncleDiff, uncle.Difficulty)
    }

    td := new(big.Int)
    td = td.Add(parentTd, uncleDiff)
    td = td.Add(td, block.Header().Difficulty)

    return td, nil
}

// Unexported method for writing extra non-essential block info to the db
func (bc *ChainManager) writeBlockInfo(block *types.Block) {
    bc.lastBlockNumber++
}

func (bc *ChainManager) Stop() {
    if bc.CurrentBlock != nil {
        chainlogger.Infoln("Stopped")
    }
}

func (self *ChainManager) InsertChain(chain types.Blocks) error {
    for _, block := range chain {
        td, err := self.processor.Process(block)
        if err != nil {
            if IsKnownBlockErr(err) {
                continue
            }

            h := block.Header()
            chainlogger.Infof("block #%v process failed (%x)\n", h.Number, h.Hash()[:4])
            chainlogger.Infoln(block)
            chainlogger.Infoln(err)
            return err
        }
        block.Td = td

        self.mu.Lock()
        {
            self.write(block)
            cblock := self.currentBlock
            if td.Cmp(self.td) > 0 {
                if block.Header().Number.Cmp(new(big.Int).Add(cblock.Header().Number, ethutil.Big1)) < 0 {
                    chainlogger.Infof("Split detected. New head #%v (%x) TD=%v, was #%v (%x) TD=%v\n", block.Header().Number, block.Hash()[:4], td, cblock.Header().Number, cblock.Hash()[:4], self.td)
                }

                self.setTotalDifficulty(td)
                self.insert(block)
                self.transState = state.New(cblock.Root(), self.db)

                self.eventMux.Post(ChainEvent{block, td})
            }
        }
        self.mu.Unlock()

        self.eventMux.Post(NewBlockEvent{block})
    }

    return nil
}

// Satisfy state query interface
func (self *ChainManager) GetAccount(addr []byte) *state.StateObject {
    return self.State().GetAccount(addr)
}