path: root/core/block_processor.go

package core

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

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/pow"
    "github.com/ethereum/go-ethereum/rlp"
    "gopkg.in/fatih/set.v0"
)

var statelogger = logger.NewLogger("BLOCK")

type BlockProcessor struct {
    db      common.Database
    extraDb common.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, extra common.Database, pow pow.PoW, txpool *TxPool, chainManager *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
    sm := &BlockProcessor{
        db:       db,
        extraDb:  extra,
        mem:      make(map[string]*big.Int),
        Pow:      pow,
        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()

    cb := statedb.GetStateObject(coinbase.Address())
    _, gas, err := ApplyMessage(NewEnv(statedb, self.bc, tx, block), tx, cb)
    if err != nil && (IsNonceErr(err) || state.IsGasLimitErr(err) || IsInvalidTxErr(err)) {
        // If the account is managed, remove the invalid nonce.
        from, _ := tx.From()
        self.bc.TxState().RemoveNonce(from, tx.Nonce())
        return nil, nil, err
    }

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

    cumulative := new(big.Int).Set(usedGas.Add(usedGas, gas))
    receipt := types.NewReceipt(statedb.Root().Bytes(), 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, gas, err
}
func (self *BlockProcessor) ChainManager() *ChainManager {
    return self.bc
}

func (self *BlockProcessor) ApplyTransactions(coinbase *state.StateObject, statedb *state.StateDB, block *types.Block, txs types.Transactions, transientProcess bool) (types.Receipts, error) {
    var (
        receipts      types.Receipts
        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 && (IsNonceErr(err) || state.IsGasLimitErr(err) || IsInvalidTxErr(err)) {
            return nil, err
        }

        if err != nil {
            statelogger.Infoln("TX err:", err)
        }
        receipts = append(receipts, receipt)

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

    block.Reward = cumulativeSum
    if block.GasUsed().Cmp(totalUsedGas) != 0 {
        return nil, ValidationError(fmt.Sprintf("gas used error (%v / %v)", block.GasUsed(), totalUsedGas))
    }

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

    return receipts, 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, logs state.Logs, 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, nil, &KnownBlockError{header.Number, header.Hash()}
    }

    if !sm.bc.HasBlock(header.ParentHash) {
        return nil, 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, logs state.Logs, 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)

    // track (possible) uncle block
    var uncle bool
    // Block validation
    if err = sm.ValidateHeader(block.Header(), parent.Header()); err != nil {
        if err != BlockEqualTSErr {
            return
        }
        err = nil
        uncle = true
    }

    // There can be at most two uncles
    if len(block.Uncles()) > 2 {
        return nil, nil, ValidationError("Block can only contain one uncle (contained %v)", len(block.Uncles()))
    }

    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 rbloom != header.Bloom {
        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 txSha != header.TxHash {
        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 receiptSha != header.ReceiptHash {
        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(common.Big0)
    if 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()

    if !uncle {
        // Remove transactions from the pool
        sm.txpool.RemoveSet(block.Transactions())
    }

    for _, tx := range block.Transactions() {
        putTx(sm.extraDb, tx)
    }

    if uncle {
        chainlogger.Infof("found possible uncle block #%d (%x...)\n", header.Number, block.Hash().Bytes()[0:4])
        return td, nil, BlockEqualTSErr
    } else {
        chainlogger.Infof("processed block #%d (%d TXs %d UNCs) (%x...)\n", header.Number, len(block.Transactions()), len(block.Uncles()), block.Hash().Bytes()[0:4])
    }

    return td, state.Logs(), 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) ValidateHeader(block, parent *types.Header) error {
    if len(block.Extra) > 1024 {
        return fmt.Errorf("Block extra data too long (%d)", len(block.Extra))
    }

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

    // block.gasLimit - parent.gasLimit <= parent.gasLimit / 1024
    a := new(big.Int).Sub(block.GasLimit, parent.GasLimit)
    b := new(big.Int).Div(parent.GasLimit, big.NewInt(1024))
    if a.Cmp(b) > 0 {
        return fmt.Errorf("GasLimit check failed for block %v (%v > %v)", block.GasLimit, a, b)
    }

    if int64(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(types.NewBlockWithHeader(block)) {
        return ValidationError("Block's nonce is invalid (= %x)", block.Nonce)
    }

    if block.Time <= parent.Time {
        return BlockEqualTSErr //ValidationError("Block timestamp equal or less than previous block (%v - %v)", block.Time, parent.Time)
    }

    return nil
}

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

    ancestors := set.New()
    uncles := set.New()
    ancestorHeaders := make(map[common.Hash]*types.Header)
    for _, ancestor := range sm.bc.GetAncestors(block, 7) {
        ancestorHeaders[ancestor.Hash()] = ancestor.Header()
        ancestors.Add(ancestor.Hash())
        // Include ancestors uncles in the uncle set. Uncles must be unique.
        for _, uncle := range ancestor.Uncles() {
            uncles.Add(uncle.Hash())
        }
    }

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

        uncles.Add(uncle.Hash())

        if ancestors.Has(uncle.Hash()) {
            return UncleError("Uncle is ancestor")
        }

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

        if err := sm.ValidateHeader(uncle, ancestorHeaders[uncle.ParentHash]); err != nil && err != BlockEqualTSErr {
            return ValidationError(fmt.Sprintf("%v", err))
        }

        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
}

func putTx(db common.Database, tx *types.Transaction) {
    rlpEnc, err := rlp.EncodeToBytes(tx)
    if err != nil {
        statelogger.Infoln("Failed encoding tx", err)
        return
    }
    db.Put(tx.Hash().Bytes(), rlpEnc)
}