path: root/ethchain/state_manager.go

package ethchain

import (
    "bytes"
    "container/list"
    "github.com/ethereum/eth-go/ethlog"
    "github.com/ethereum/eth-go/ethutil"
    "github.com/ethereum/eth-go/ethwire"
    "math/big"
    "sync"
    "time"
)

var statelogger = ethlog.NewLogger("STATE")

type BlockProcessor interface {
    ProcessBlock(block *Block)
}

type Peer interface {
    Inbound() bool
    LastSend() time.Time
    LastPong() int64
    Host() []byte
    Port() uint16
    Version() string
    PingTime() string
    Connected() *int32
}

type EthManager interface {
    StateManager() *StateManager
    BlockChain() *BlockChain
    TxPool() *TxPool
    Broadcast(msgType ethwire.MsgType, data []interface{})
    Reactor() *ethutil.ReactorEngine
    PeerCount() int
    IsMining() bool
    IsListening() bool
    Peers() *list.List
}

type StateManager struct {
    // Mutex for locking the block processor. Blocks can only be handled one at a time
    mutex sync.Mutex
    // Canonical block chain
    bc *BlockChain
    // Stack for processing contracts
    stack *Stack
    // non-persistent key/value memory storage
    mem map[string]*big.Int
    // Proof of work used for validating
    Pow PoW
    // The ethereum manager interface
    Ethereum EthManager
    // The managed states
    // Transiently state. The trans state isn't ever saved, validated and
    // it could be used for setting account nonces without effecting
    // the main states.
    transState *State
    // Mining state. The mining state is used purely and solely by the mining
    // operation.
    miningState *State
}

func NewStateManager(ethereum EthManager) *StateManager {
    sm := &StateManager{
        stack:    NewStack(),
        mem:      make(map[string]*big.Int),
        Pow:      &EasyPow{},
        Ethereum: ethereum,
        bc:       ethereum.BlockChain(),
    }
    sm.transState = ethereum.BlockChain().CurrentBlock.State().Copy()
    sm.miningState = ethereum.BlockChain().CurrentBlock.State().Copy()

    return sm
}

func (sm *StateManager) CurrentState() *State {
    return sm.Ethereum.BlockChain().CurrentBlock.State()
}

func (sm *StateManager) TransState() *State {
    return sm.transState
}

func (sm *StateManager) MiningState() *State {
    return sm.miningState
}

func (sm *StateManager) NewMiningState() *State {
    sm.miningState = sm.Ethereum.BlockChain().CurrentBlock.State().Copy()

    return sm.miningState
}

func (sm *StateManager) BlockChain() *BlockChain {
    return sm.bc
}

func (self *StateManager) ProcessTransactions(coinbase *StateObject, state *State, block, parent *Block, txs Transactions) (Receipts, Transactions, Transactions, error) {
    var (
        receipts           Receipts
        handled, unhandled Transactions
        totalUsedGas       = big.NewInt(0)
        err                error
    )

done:
    for i, tx := range txs {
        txGas := new(big.Int).Set(tx.Gas)
        st := NewStateTransition(coinbase, tx, state, block)
        err = st.TransitionState()
        if err != nil {
            switch {
            case IsNonceErr(err):
                err = nil // ignore error
                continue
            case IsGasLimitErr(err):
                unhandled = txs[i:]

                break done
            default:
                statelogger.Infoln(err)
            }
        }

        // Notify all subscribers
        self.Ethereum.Reactor().Post("newTx:post", tx)

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

        txGas.Sub(txGas, st.gas)
        accumelative := new(big.Int).Set(totalUsedGas.Add(totalUsedGas, txGas))
        receipt := &Receipt{tx, ethutil.CopyBytes(state.Root().([]byte)), accumelative}

        receipts = append(receipts, receipt)
        handled = append(handled, tx)
    }

    parent.GasUsed = totalUsedGas

    return receipts, handled, unhandled, err
}

func (sm *StateManager) Process(block *Block, dontReact bool) (err error) {
    // Processing a blocks may never happen simultaneously
    sm.mutex.Lock()
    defer sm.mutex.Unlock()

    if sm.bc.HasBlock(block.Hash()) {
        return nil
    }

    if !sm.bc.HasBlock(block.PrevHash) {
        return ParentError(block.PrevHash)
    }

    var (
        parent = sm.bc.GetBlock(block.PrevHash)
        state  = parent.State()
    )

    // Defer the Undo on the Trie. If the block processing happened
    // we don't want to undo but since undo only happens on dirty
    // nodes this won't happen because Commit would have been called
    // before that.
    defer state.Reset()

    receipts, err := sm.ApplyDiff(state, parent, block)
    defer func() {
        if err != nil {
            if len(receipts) == len(block.Receipts()) {
                for i, receipt := range block.Receipts() {
                    statelogger.Debugf("diff (r) %v ~ %x  <=>  (c) %v ~ %x (%x)\n", receipt.CumulativeGasUsed, receipt.PostState[0:4], receipts[i].CumulativeGasUsed, receipts[i].PostState[0:4], receipt.Tx.Hash())
                }
            } else {
                statelogger.Warnln("Unable to print receipt diff. Length didn't match", len(receipts), "for", len(block.Receipts()))
            }
        }
    }()

    if err != nil {
        return err
    }

    // Block validation
    if err = sm.ValidateBlock(block); err != nil {
        statelogger.Errorln("Error validating block:", err)
        return err
    }

    // I'm not sure, but I don't know if there should be thrown
    // any errors at this time.
    if err = sm.AccumelateRewards(state, block); err != nil {
        statelogger.Errorln("Error accumulating reward", err)
        return err
    }

    if !block.State().Cmp(state) {
        statelogger.Errorf("Invalid merkle root.\nrec: %x\nis:  %x", block.State().trie.Root, state.trie.Root)
        return
    }

    // Calculate the new total difficulty and sync back to the db
    if sm.CalculateTD(block) {
        // Sync the current block's state to the database and cancelling out the deferred Undo
        state.Sync()

        // Add the block to the chain
        sm.bc.Add(block)
        sm.notifyChanges(state)

        statelogger.Infof("Added block #%d (%x)\n", block.Number, block.Hash())
        if dontReact == false {
            sm.Ethereum.Reactor().Post("newBlock", block)

            state.manifest.Reset()
        }

        sm.Ethereum.Broadcast(ethwire.MsgBlockTy, []interface{}{block.Value().Val})

        sm.Ethereum.TxPool().RemoveInvalid(state)
    } else {
        statelogger.Errorln("total diff failed")
    }

    return nil
}

func (sm *StateManager) ApplyDiff(state *State, parent, block *Block) (receipts Receipts, err error) {
    coinbase := state.GetOrNewStateObject(block.Coinbase)
    coinbase.SetGasPool(block.CalcGasLimit(parent))

    // Process the transactions on to current block
    receipts, _, _, _ = sm.ProcessTransactions(coinbase, state, block, parent, block.Transactions())

    return receipts, nil
}

func (sm *StateManager) CalculateTD(block *Block) bool {
    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(sm.bc.TD, uncleDiff)
    td = td.Add(td, block.Difficulty)

    // The new TD will only be accepted if the new difficulty is
    // is greater than the previous.
    if td.Cmp(sm.bc.TD) > 0 {
        // Set the new total difficulty back to the block chain
        sm.bc.SetTotalDifficulty(td)

        return true
    }

    return false
}

// 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 *StateManager) ValidateBlock(block *Block) error {
    // TODO
    // 2. Check if the difficulty is correct

    // Check each uncle's previous hash. In order for it to be valid
    // is if it has the same block hash as the current
    previousBlock := sm.bc.GetBlock(block.PrevHash)
    for _, uncle := range block.Uncles {
        if bytes.Compare(uncle.PrevHash, previousBlock.PrevHash) != 0 {
            return ValidationError("Mismatch uncle's previous hash. Expected %x, got %x", previousBlock.PrevHash, uncle.PrevHash)
        }
    }

    diff := block.Time - sm.bc.CurrentBlock.Time
    if diff < 0 {
        return ValidationError("Block timestamp less then prev block %v", diff)
    }

    /* XXX
    // New blocks must be within the 15 minute range of the last block.
    if diff > int64(15*time.Minute) {
        return ValidationError("Block is too far in the future of last block (> 15 minutes)")
    }
    */

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

    return nil
}

func CalculateBlockReward(block *Block, uncleLength int) *big.Int {
    base := new(big.Int)
    for i := 0; i < uncleLength; i++ {
        base.Add(base, UncleInclusionReward)
    }

    return base.Add(base, BlockReward)
}

func CalculateUncleReward(block *Block) *big.Int {
    return UncleReward
}

func (sm *StateManager) AccumelateRewards(state *State, block *Block) error {
    // Get the account associated with the coinbase
    account := state.GetAccount(block.Coinbase)
    // Reward amount of ether to the coinbase address
    account.AddAmount(CalculateBlockReward(block, len(block.Uncles)))

    addr := make([]byte, len(block.Coinbase))
    copy(addr, block.Coinbase)
    state.UpdateStateObject(account)

    for _, uncle := range block.Uncles {
        uncleAccount := state.GetAccount(uncle.Coinbase)
        uncleAccount.AddAmount(CalculateUncleReward(uncle))

        state.UpdateStateObject(uncleAccount)
    }

    return nil
}

func (sm *StateManager) Stop() {
    sm.bc.Stop()
}

func (sm *StateManager) notifyChanges(state *State) {
    for addr, stateObject := range state.manifest.objectChanges {
        sm.Ethereum.Reactor().Post("object:"+addr, stateObject)
    }

    for stateObjectAddr, mappedObjects := range state.manifest.storageChanges {
        for addr, value := range mappedObjects {
            sm.Ethereum.Reactor().Post("storage:"+stateObjectAddr+":"+addr, &StorageState{[]byte(stateObjectAddr), []byte(addr), value})
        }
    }
}