path: root/core/block_processor.go

package core

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

    "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/pow"
    "github.com/ethereum/go-ethereum/pow/ezp"
    "github.com/ethereum/go-ethereum/state"
    "gopkg.in/fatih/set.v0"
)

type PendingBlockEvent struct {
    Block *types.Block
}

var statelogger = logger.NewLogger("BLOCK")

type BlockProcessor struct {
    db ethutil.Database
    // Mutex for locking the block processor. Blocks can only be handled one at a time
    mutex sync.Mutex
    // Canonical block chain
    bc *ChainManager
    // non-persistent key/value memory storage
    mem map[string]*big.Int
    // Proof of work used for validating
    Pow pow.PoW

    txpool *TxPool

    // The last attempted block is mainly used for debugging purposes
    // This does not have to be a valid block and will be set during
    // 'Process' & canonical validation.
    lastAttemptedBlock *types.Block

    events event.Subscription

    eventMux *event.TypeMux
}

func NewBlockProcessor(db ethutil.Database, txpool *TxPool, chainManager *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
    sm := &BlockProcessor{
        db:       db,
        mem:      make(map[string]*big.Int),
        Pow:      ezp.New(),
        bc:       chainManager,
        eventMux: eventMux,
        txpool:   txpool,
    }

    return sm
}

func (sm *BlockProcessor) TransitionState(statedb *state.StateDB, parent, block *types.Block, transientProcess bool) (receipts types.Receipts, err error) {
    coinbase := statedb.GetOrNewStateObject(block.Header().Coinbase)
    coinbase.SetGasPool(block.Header().GasLimit)

    // Process the transactions on to parent state
    receipts, _, _, _, err = sm.ApplyTransactions(coinbase, statedb, block, block.Transactions(), transientProcess)
    if err != nil {
        return nil, err
    }

    return receipts, nil
}

func (self *BlockProcessor) ApplyTransaction(coinbase *state.StateObject, statedb *state.StateDB, block *types.Block, tx *types.Transaction, usedGas *big.Int, transientProcess bool) (*types.Receipt, *big.Int, error) {
    // If we are mining this block and validating we want to set the logs back to 0
    statedb.EmptyLogs()

    txGas := new(big.Int).Set(tx.Gas())

    cb := statedb.GetStateObject(coinbase.Address())
    st := NewStateTransition(NewEnv(statedb, self.bc, tx, block), tx, cb)
    _, err := st.TransitionState()
    if err != nil && (IsNonceErr(err) || state.IsGasLimitErr(err)) {
        return nil, nil, err
    }

    txGas.Sub(txGas, st.gas)

    // Update the state with pending changes
    statedb.Update(txGas)

    cumulative := new(big.Int).Set(usedGas.Add(usedGas, txGas))
    receipt := types.NewReceipt(statedb.Root(), cumulative)
    receipt.SetLogs(statedb.Logs())
    receipt.Bloom = types.CreateBloom(types.Receipts{receipt})
    chainlogger.Debugln(receipt)

    // Notify all subscribers
    if !transientProcess {
        go self.eventMux.Post(TxPostEvent{tx})
        logs := statedb.Logs()
        go self.eventMux.Post(logs)
    }

    return receipt, txGas, err
}

func (self *BlockProcessor) ApplyTransactions(coinbase *state.StateObject, statedb *state.StateDB, block *types.Block, txs types.Transactions, transientProcess bool) (types.Receipts, types.Transactions, types.Transactions, types.Transactions, error) {
    var (
        receipts           types.Receipts
        handled, unhandled types.Transactions
        erroneous          types.Transactions
        totalUsedGas       = big.NewInt(0)
        err                error
        cumulativeSum      = new(big.Int)
    )

    for _, tx := range txs {
        receipt, txGas, err := self.ApplyTransaction(coinbase, statedb, block, tx, totalUsedGas, transientProcess)
        if err != nil {
            switch {
            case IsNonceErr(err):
                return nil, nil, nil, nil, err
            case state.IsGasLimitErr(err):
                return nil, nil, nil, nil, err
            default:
                statelogger.Infoln(err)
                erroneous = append(erroneous, tx)
                err = nil
            }
        }
        receipts = append(receipts, receipt)
        handled = append(handled, tx)

        cumulativeSum.Add(cumulativeSum, new(big.Int).Mul(txGas, tx.GasPrice()))
    }

    block.Reward = cumulativeSum
    block.Header().GasUsed = totalUsedGas

    if transientProcess {
        go self.eventMux.Post(PendingBlockEvent{block})
    }

    return receipts, handled, unhandled, erroneous, err
}

// Process block will attempt to process the given block's transactions and applies them
// on top of the block's parent state (given it exists) and will return wether it was
// successful or not.
func (sm *BlockProcessor) Process(block *types.Block) (td *big.Int, err error) {
    // Processing a blocks may never happen simultaneously
    sm.mutex.Lock()
    defer sm.mutex.Unlock()

    header := block.Header()
    if sm.bc.HasBlock(header.Hash()) {
        return nil, &KnownBlockError{header.Number, header.Hash()}
    }

    if !sm.bc.HasBlock(header.ParentHash) {
        return nil, ParentError(header.ParentHash)
    }
    parent := sm.bc.GetBlock(header.ParentHash)

    return sm.processWithParent(block, parent)
}

func (sm *BlockProcessor) processWithParent(block, parent *types.Block) (td *big.Int, err error) {
    sm.lastAttemptedBlock = block

    // Create a new state based on the parent's root (e.g., create copy)
    state := state.New(parent.Root(), sm.db)

    // Block validation
    if err = sm.ValidateBlock(block, parent); err != nil {
        return
    }

    receipts, err := sm.TransitionState(state, parent, block, false)
    if err != nil {
        return
    }

    header := block.Header()

    // Validate the received block's bloom with the one derived from the generated receipts.
    // For valid blocks this should always validate to true.
    rbloom := types.CreateBloom(receipts)
    if bytes.Compare(rbloom, header.Bloom) != 0 {
        err = fmt.Errorf("unable to replicate block's bloom=%x", rbloom)
        return
    }

    // The transactions Trie's root (R = (Tr [[H1, T1], [H2, T2], ... [Hn, Tn]]))
    // can be used by light clients to make sure they've received the correct Txs
    txSha := types.DeriveSha(block.Transactions())
    if bytes.Compare(txSha, header.TxHash) != 0 {
        err = fmt.Errorf("validating transaction root. received=%x got=%x", header.TxHash, txSha)
        return
    }

    // Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
    receiptSha := types.DeriveSha(receipts)
    if bytes.Compare(receiptSha, header.ReceiptHash) != 0 {
        fmt.Println("receipts", receipts)
        err = fmt.Errorf("validating receipt root. received=%x got=%x", header.ReceiptHash, receiptSha)
        return
    }

    // Accumulate static rewards; block reward, uncle's and uncle inclusion.
    if err = sm.AccumulateRewards(state, block, parent); err != nil {
        return
    }

    // Commit state objects/accounts to a temporary trie (does not save)
    // used to calculate the state root.
    state.Update(ethutil.Big0)
    if !bytes.Equal(header.Root, state.Root()) {
        err = fmt.Errorf("invalid merkle root. received=%x got=%x", header.Root, state.Root())
        return
    }

    // Calculate the td for this block
    td = CalculateTD(block, parent)
    // Sync the current block's state to the database
    state.Sync()
    // Remove transactions from the pool
    sm.txpool.RemoveSet(block.Transactions())

    chainlogger.Infof("processed block #%d (%x...)\n", header.Number, block.Hash()[0:4])

    return td, nil
}

// Validates the current block. Returns an error if the block was invalid,
// an uncle or anything that isn't on the current block chain.
// Validation validates easy over difficult (dagger takes longer time = difficult)
func (sm *BlockProcessor) ValidateBlock(block, parent *types.Block) error {
    if len(block.Header().Extra) > 1024 {
        return fmt.Errorf("Block extra data too long (%d)", len(block.Header().Extra))
    }

    expd := CalcDifficulty(block, parent)
    if expd.Cmp(block.Header().Difficulty) != 0 {
        return fmt.Errorf("Difficulty check failed for block %v, %v", block.Header().Difficulty, expd)
    }

    expl := CalcGasLimit(parent, block)
    if expl.Cmp(block.Header().GasLimit) != 0 {
        return fmt.Errorf("GasLimit check failed for block %v, %v", block.Header().GasLimit, expl)
    }

    if block.Time() < parent.Time() {
        return ValidationError("Block timestamp not after prev block (%v - %v)", block.Header().Time, parent.Header().Time)
    }

    if block.Time() > time.Now().Unix() {
        return BlockFutureErr
    }

    if new(big.Int).Sub(block.Number(), parent.Number()).Cmp(big.NewInt(1)) != 0 {
        return BlockNumberErr
    }

    // Verify the nonce of the block. Return an error if it's not valid
    if !sm.Pow.Verify(block) {
        return ValidationError("Block's nonce is invalid (= %v)", ethutil.Bytes2Hex(block.Header().Nonce))
    }

    return nil
}

func (sm *BlockProcessor) AccumulateRewards(statedb *state.StateDB, block, parent *types.Block) error {
    reward := new(big.Int).Set(BlockReward)

    ancestors := set.New()
    for _, ancestor := range sm.bc.GetAncestors(block, 7) {
        ancestors.Add(string(ancestor.Hash()))
    }

    uncles := set.New()
    uncles.Add(string(block.Hash()))
    for _, uncle := range block.Uncles() {
        if uncles.Has(string(uncle.Hash())) {
            // Error not unique
            return UncleError("Uncle not unique")
        }
        uncles.Add(string(uncle.Hash()))

        if !ancestors.Has(string(uncle.ParentHash)) {
            return UncleError(fmt.Sprintf("Uncle's parent unknown (%x)", uncle.ParentHash[0:4]))
        }

        if !sm.Pow.Verify(types.NewBlockWithHeader(uncle)) {
            return ValidationError("Uncle's nonce is invalid (= %v)", ethutil.Bytes2Hex(uncle.Nonce))
        }

        r := new(big.Int)
        r.Mul(BlockReward, big.NewInt(15)).Div(r, big.NewInt(16))

        statedb.AddBalance(uncle.Coinbase, r)

        reward.Add(reward, new(big.Int).Div(BlockReward, big.NewInt(32)))
    }

    // Get the account associated with the coinbase
    statedb.AddBalance(block.Header().Coinbase, reward)

    return nil
}

func (sm *BlockProcessor) GetLogs(block *types.Block) (logs state.Logs, err error) {
    if !sm.bc.HasBlock(block.Header().ParentHash) {
        return nil, ParentError(block.Header().ParentHash)
    }

    sm.lastAttemptedBlock = block

    var (
        parent = sm.bc.GetBlock(block.Header().ParentHash)
        state  = state.New(parent.Root(), sm.db)
    )

    sm.TransitionState(state, parent, block, true)
    sm.AccumulateRewards(state, block, parent)

    return state.Logs(), nil
}