path: root/ethchain/state_manager.go

package ethchain

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

type BlockProcessor interface {
    ProcessBlock(block *Block)
}

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

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
    // Processor state. Anything processed will be applied to this
    // state
    procState *State
    // Comparative state it used for comparing and validating end
    // results
    compState *State
    // 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
    // Manifest for keeping changes regarding state objects. See `notify`
    // XXX Should we move the manifest to the State object. Benefit:
    // * All states can keep their own local changes
    //manifest *Manifest
}

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

    return sm
}

func (sm *StateManager) ProcState() *State {
    return sm.procState
}

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

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

func (sm *StateManager) MakeContract(tx *Transaction) *StateObject {
    contract := MakeContract(tx, sm.procState)
    if contract != nil {
        sm.procState.states[string(tx.Hash()[12:])] = contract.state

        return contract
    }

    return nil
}

// Apply transactions uses the transaction passed to it and applies them onto
// the current processing state.
func (sm *StateManager) ApplyTransactions(block *Block, txs []*Transaction) {
    // Process each transaction/contract
    for _, tx := range txs {
        // If there's no recipient, it's a contract
        // Check if this is a contract creation traction and if so
        // create a contract of this tx.
        if tx.IsContract() {
            err := sm.Ethereum.TxPool().ProcessTransaction(tx, block, false)
            if err == nil {
                contract := sm.MakeContract(tx)
                if contract != nil {
                    sm.EvalScript(contract.Init(), contract, tx, block)
                } else {
                    ethutil.Config.Log.Infoln("[STATE] Unable to create contract")
                }
            } else {
                ethutil.Config.Log.Infoln("[STATE] contract create:", err)
            }
        } else {
            err := sm.Ethereum.TxPool().ProcessTransaction(tx, block, false)
            contract := sm.procState.GetContract(tx.Recipient)
            if err == nil && len(contract.Script()) > 0 {
                sm.EvalScript(contract.Script(), contract, tx, block)
            } else if err != nil {
                ethutil.Config.Log.Infoln("[STATE] process:", err)
            }
        }
    }
}

// The prepare function, prepares the state manager for the next
// "ProcessBlock" action.
func (sm *StateManager) Prepare(processor *State, comparative *State) {
    sm.compState = comparative
    sm.procState = processor
}

// Default prepare function
func (sm *StateManager) PrepareDefault(block *Block) {
    sm.Prepare(sm.BlockChain().CurrentBlock.State(), block.State())
}

// Block processing and validating with a given (temporarily) state
func (sm *StateManager) ProcessBlock(block *Block, dontReact bool) error {
    // Processing a blocks may never happen simultaneously
    sm.mutex.Lock()
    defer sm.mutex.Unlock()
    hash := block.Hash()

    if sm.bc.HasBlock(hash) {
        //fmt.Println("[STATE] We already have this block, ignoring")
        return nil
    }

    // 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 sm.bc.CurrentBlock.Undo()

    // Check if we have the parent hash, if it isn't known we discard it
    // Reasons might be catching up or simply an invalid block
    if !sm.bc.HasBlock(block.PrevHash) && sm.bc.CurrentBlock != nil {
        return ParentError(block.PrevHash)
    }

    // Process the transactions on to current block
    sm.ApplyTransactions(sm.bc.CurrentBlock, block.Transactions())

    // Block validation
    if err := sm.ValidateBlock(block); err != nil {
        fmt.Println("[SM] 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(block); err != nil {
        fmt.Println("[SM] Error accumulating reward", err)
        return err
    }

    if !sm.compState.Cmp(sm.procState) {
        return fmt.Errorf("Invalid merkle root. Expected %x, got %x", sm.compState.trie.Root, sm.procState.trie.Root)
    }

    // 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
        sm.procState.Sync()

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

        ethutil.Config.Log.Infof("[STATE] Added block #%d (%x)\n", block.BlockInfo().Number, block.Hash())
        if dontReact == false {
            sm.Ethereum.Reactor().Post("newBlock", block)

            sm.notifyChanges()

            sm.procState.manifest.Reset()
        }

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

    } else {
        fmt.Println("total diff failed")
    }

    return 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)
    }

    // 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(block *Block) error {
    // Get the account associated with the coinbase
    account := sm.procState.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)
    sm.procState.UpdateStateObject(account)

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

        sm.procState.UpdateStateObject(uncleAccount)
    }

    return nil
}

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

func (sm *StateManager) EvalScript(script []byte, object *StateObject, tx *Transaction, block *Block) {
    account := sm.procState.GetAccount(tx.Sender())

    err := account.ConvertGas(tx.Gas, tx.GasPrice)
    if err != nil {
        ethutil.Config.Log.Debugln(err)
        return
    }

    closure := NewClosure(account, object, script, sm.procState, tx.Gas, tx.GasPrice)
    vm := NewVm(sm.procState, sm, RuntimeVars{
        Origin:      account.Address(),
        BlockNumber: block.BlockInfo().Number,
        PrevHash:    block.PrevHash,
        Coinbase:    block.Coinbase,
        Time:        block.Time,
        Diff:        block.Difficulty,
        Value:       tx.Value,
        //Price:       tx.GasPrice,
    })
    closure.Call(vm, tx.Data, nil)

    // Update the account (refunds)
    sm.procState.UpdateStateObject(account)
    sm.procState.UpdateStateObject(object)
}

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

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