path: root/core/chain_manager.go

package core

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

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
    "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")
    jsonlogger  = logger.NewJsonLogger()

    blockHashPre = []byte("block-hash-")
    blockNumPre  = []byte("block-num-")
)

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

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

    min := big.NewInt(2048)
    adjust := new(big.Int).Div(parent.Difficulty, min)
    if (block.Time - parent.Time) < 8 {
        diff.Add(parent.Difficulty, adjust)
    } else {
        diff.Sub(parent.Difficulty, adjust)
    }

    if diff.Cmp(GenesisDiff) < 0 {
        return GenesisDiff
    }

    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 common.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))

    return common.BigMax(GenesisGasLimit, result)
}

type ChainManager struct {
    //eth          EthManager
    blockDb      common.Database
    stateDb      common.Database
    processor    types.BlockProcessor
    eventMux     *event.TypeMux
    genesisBlock *types.Block
    // Last known total difficulty
    mu            sync.RWMutex
    tsmu          sync.RWMutex
    td            *big.Int
    currentBlock  *types.Block
    lastBlockHash common.Hash

    transState *state.StateDB
    txState    *state.ManagedState

    quit chan struct{}
}

func NewChainManager(blockDb, stateDb common.Database, mux *event.TypeMux) *ChainManager {
    bc := &ChainManager{blockDb: blockDb, stateDb: stateDb, genesisBlock: GenesisBlock(stateDb), eventMux: mux, quit: make(chan struct{})}
    bc.setLastBlock()
    bc.transState = bc.State().Copy()
    // Take ownership of this particular state
    bc.txState = state.ManageState(bc.State().Copy())
    go bc.update()

    return bc
}

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

    return self.td
}

func (self *ChainManager) LastBlockHash() common.Hash {
    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 (self *ChainManager) Status() (td *big.Int, currentBlock common.Hash, genesisBlock common.Hash) {
    self.mu.RLock()
    defer self.mu.RUnlock()

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

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

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

func (self *ChainManager) TransState() *state.StateDB {
    self.tsmu.RLock()
    defer self.tsmu.RUnlock()

    return self.transState
}

func (self *ChainManager) TxState() *state.ManagedState {
    self.tsmu.RLock()
    defer self.tsmu.RUnlock()

    return self.txState
}

func (self *ChainManager) setTxState(statedb *state.StateDB) {
    self.tsmu.Lock()
    defer self.tsmu.Unlock()
    self.txState = state.ManageState(statedb)
}

func (self *ChainManager) setTransState(statedb *state.StateDB) {
    self.transState = statedb
}

func (bc *ChainManager) setLastBlock() {
    data, _ := bc.blockDb.Get([]byte("LastBlock"))
    if len(data) != 0 {
        block := bc.GetBlock(common.BytesToHash(data))
        bc.currentBlock = block
        bc.lastBlockHash = block.Hash()

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

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

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

    var (
        root       common.Hash
        parentHash common.Hash
    )

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

    block := types.NewBlock(
        parentHash,
        coinbase,
        root,
        common.BigPow(2, 32),
        0,
        "")
    block.SetUncles(nil)
    block.SetTransactions(nil)
    block.SetReceipts(nil)

    parent := bc.currentBlock
    if parent != nil {
        header := block.Header()
        header.Difficulty = CalcDifficulty(block.Header(), parent.Header())
        header.Number = new(big.Int).Add(parent.Header().Number, common.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.removeBlock(block)
    }

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

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

func (bc *ChainManager) removeBlock(block *types.Block) {
    bc.blockDb.Delete(append(blockHashPre, block.Hash().Bytes()...))
}

func (bc *ChainManager) ResetWithGenesisBlock(gb *types.Block) {
    bc.mu.Lock()
    defer bc.mu.Unlock()

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

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

// Export writes the active chain to the given writer.
func (self *ChainManager) Export(w io.Writer) error {
    self.mu.RLock()
    defer self.mu.RUnlock()
    chainlogger.Infof("exporting %v blocks...\n", self.currentBlock.Header().Number)
    for block := self.currentBlock; block != nil; block = self.GetBlock(block.Header().ParentHash) {
        if err := block.EncodeRLP(w); err != nil {
            return err
        }
    }
    return nil
}

func (bc *ChainManager) insert(block *types.Block) {
    bc.blockDb.Put([]byte("LastBlock"), block.Hash().Bytes())
    bc.currentBlock = block
    bc.lastBlockHash = block.Hash()

    key := append(blockNumPre, block.Number().Bytes()...)
    bc.blockDb.Put(key, bc.lastBlockHash.Bytes())
}

func (bc *ChainManager) write(block *types.Block) {
    enc, _ := rlp.EncodeToBytes((*types.StorageBlock)(block))
    key := append(blockHashPre, block.Hash().Bytes()...)
    bc.blockDb.Put(key, enc)
}

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

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

func (self *ChainManager) GetBlockHashesFromHash(hash common.Hash, max uint64) (chain []common.Hash) {
    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(common.Big0) <= 0 {
            break
        }
    }

    return
}

func (self *ChainManager) GetBlock(hash common.Hash) *types.Block {
    data, _ := self.blockDb.Get(append(blockHashPre, hash[:]...))
    if len(data) == 0 {
        return nil
    }
    var block types.StorageBlock
    if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
        chainlogger.Errorf("invalid block RLP for hash %x: %v", hash, err)
        return nil
    }
    return (*types.Block)(&block)
}

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

    key, _ := self.blockDb.Get(append(blockNumPre, big.NewInt(int64(num)).Bytes()...))
    if len(key) == 0 {
        return nil
    }

    return self.GetBlock(common.BytesToHash(key))
}

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 (bc *ChainManager) setTotalDifficulty(td *big.Int) {
    bc.blockDb.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
}

func (bc *ChainManager) Stop() {
    close(bc.quit)
}

type queueEvent struct {
    queue          []interface{}
    canonicalCount int
    sideCount      int
    splitCount     int
}

func (self *ChainManager) InsertChain(chain types.Blocks) error {
    //self.tsmu.Lock()
    //defer self.tsmu.Unlock()

    // A queued approach to delivering events. This is generally faster than direct delivery and requires much less mutex acquiring.
    var queue = make([]interface{}, len(chain))
    var queueEvent = queueEvent{queue: queue}
    for i, block := range chain {
        // Call in to the block processor and check for errors. It's likely that if one block fails
        // all others will fail too (unless a known block is returned).
        td, err := self.processor.Process(block)
        if err != nil {
            if IsKnownBlockErr(err) {
                continue
            }

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

        self.mu.Lock()
        cblock := self.currentBlock
        {
            // Write block to database. Eventually we'll have to improve on this and throw away blocks that are
            // not in the canonical chain.
            self.write(block)
            // Compare the TD of the last known block in the canonical chain to make sure it's greater.
            // At this point it's possible that a different chain (fork) becomes the new canonical chain.
            if td.Cmp(self.td) > 0 {
                if block.Header().Number.Cmp(new(big.Int).Add(cblock.Header().Number, common.Big1)) < 0 {
                    chash := cblock.Hash()
                    hash := block.Hash()
                    chainlogger.Infof("Split detected. New head #%v (%x) TD=%v, was #%v (%x) TD=%v\n", block.Header().Number, hash[:4], td, cblock.Header().Number, chash[:4], self.td)

                    queue[i] = ChainSplitEvent{block}
                    queueEvent.splitCount++
                }

                self.setTotalDifficulty(td)
                self.insert(block)

                /* XXX crashes
                jsonlogger.LogJson(&logger.EthChainNewHead{
                    BlockHash:     common.Bytes2Hex(block.Hash()),
                    BlockNumber:   block.Number(),
                    ChainHeadHash: common.Bytes2Hex(cblock.Hash()),
                    BlockPrevHash: common.Bytes2Hex(block.ParentHash()),
                })
                */

                self.setTransState(state.New(block.Root(), self.stateDb))
                self.setTxState(state.New(block.Root(), self.stateDb))

                queue[i] = ChainEvent{block}
                queueEvent.canonicalCount++
            } else {
                queue[i] = ChainSideEvent{block}
                queueEvent.sideCount++
            }
        }
        self.mu.Unlock()

    }

    // XXX put this in a goroutine?
    go self.eventMux.Post(queueEvent)

    return nil
}

func (self *ChainManager) update() {
    events := self.eventMux.Subscribe(queueEvent{})

out:
    for {
        select {
        case ev := <-events.Chan():
            switch ev := ev.(type) {
            case queueEvent:
                for i, event := range ev.queue {
                    switch event := event.(type) {
                    case ChainEvent:
                        // We need some control over the mining operation. Acquiring locks and waiting for the miner to create new block takes too long
                        // and in most cases isn't even necessary.
                        if i == ev.canonicalCount {
                            self.eventMux.Post(ChainHeadEvent{event.Block})
                        }
                    case ChainSplitEvent:
                        // On chain splits we need to reset the transaction state. We can't be sure whether the actual
                        // state of the accounts are still valid.
                        if i == ev.splitCount {
                            self.setTxState(state.New(event.Block.Root(), self.stateDb))
                        }
                    }

                    self.eventMux.Post(event)
                }
            }
        case <-self.quit:
            break out
        }
    }
}

/*
// Satisfy state query interface
func (self *ChainManager) GetAccount(addr common.Hash) *state.StateObject {
    return self.State().GetAccount(addr)
}
*/