path: root/dex/app.go

// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.

package dex

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

    coreCommon "github.com/dexon-foundation/dexon-consensus/common"
    coreTypes "github.com/dexon-foundation/dexon-consensus/core/types"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core"
    "github.com/dexon-foundation/dexon/core/rawdb"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/event"
    "github.com/dexon-foundation/dexon/log"
    "github.com/dexon-foundation/dexon/rlp"
)

// DexconApp implements the DEXON consensus core application interface.
type DexconApp struct {
    txPool     *core.TxPool
    blockchain *core.BlockChain
    gov        *DexconGovernance
    chainDB    ethdb.Database
    config     *Config

    finalizedBlockFeed event.Feed
    scope              event.SubscriptionScope

    chainLocks sync.Map
    chainRoot  sync.Map
}

func NewDexconApp(txPool *core.TxPool, blockchain *core.BlockChain, gov *DexconGovernance,
    chainDB ethdb.Database, config *Config) *DexconApp {
    return &DexconApp{
        txPool:     txPool,
        blockchain: blockchain,
        gov:        gov,
        chainDB:    chainDB,
        config:     config,
    }
}

func (d *DexconApp) addrBelongsToChain(address common.Address, chainSize, chainID *big.Int) bool {
    return true
}

func (d *DexconApp) chainLock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        v, _ = d.chainLocks.LoadOrStore(chainID, &sync.RWMutex{})
    }
    v.(*sync.RWMutex).Lock()
}

func (d *DexconApp) chainUnlock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        panic(fmt.Errorf("chain %v is not init yet", chainID))
    }
    v.(*sync.RWMutex).Unlock()
}

func (d *DexconApp) chainRLock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        v, _ = d.chainLocks.LoadOrStore(chainID, &sync.RWMutex{})
    }
    v.(*sync.RWMutex).RLock()
}

func (d *DexconApp) chainRUnlock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        panic(fmt.Errorf("chain %v is not init yet", chainID))
    }
    v.(*sync.RWMutex).RUnlock()
}

// validateNonce check if nonce is in order and return first nonce of every address.
func (d *DexconApp) validateNonce(txs types.Transactions) (map[common.Address]uint64, error) {
    addressFirstNonce := map[common.Address]uint64{}
    addressNonce := map[common.Address]uint64{}

    for _, tx := range txs {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            return nil, err
        }

        if _, exist := addressFirstNonce[msg.From()]; exist {
            if addressNonce[msg.From()]+1 != msg.Nonce() {
                return nil, fmt.Errorf("address nonce check error: expect %v actual %v",
                    addressNonce[msg.From()]+1, msg.Nonce())
            }
            addressNonce[msg.From()] = msg.Nonce()
        } else {
            addressNonce[msg.From()] = msg.Nonce()
            addressFirstNonce[msg.From()] = msg.Nonce()
        }
    }
    return addressFirstNonce, nil
}

// validateGasPrice checks if no gas price is lower than minGasPrice defined in
// governance contract.
func (d *DexconApp) validateGasPrice(txs types.Transactions, round uint64) bool {
    minGasPrice := d.gov.MinGasPrice(round)
    for _, tx := range txs {
        if minGasPrice.Cmp(tx.GasPrice()) > 0 {
            return false
        }
    }
    return true
}

// PreparePayload is called when consensus core is preparing payload for block.
func (d *DexconApp) PreparePayload(position coreTypes.Position) (payload []byte, err error) {
    // softLimit limits the runtime of inner call to preparePayload.
    // hardLimit limits the runtime of outer PreparePayload.
    // If hardLimit is hit, it is possible that no payload is prepared.
    softLimit := 100 * time.Millisecond
    hardLimit := 150 * time.Millisecond
    ctx, cancel := context.WithTimeout(context.Background(), hardLimit)
    defer cancel()
    payloadCh := make(chan []byte, 1)
    errCh := make(chan error, 1)
    doneCh := make(chan struct{}, 1)
    go func() {
        ctx, cancel := context.WithTimeout(context.Background(), softLimit)
        defer cancel()
        payload, err := d.preparePayload(ctx, position)
        if err != nil {
            errCh <- err
        }
        payloadCh <- payload
        doneCh <- struct{}{}
    }()
    select {
    case <-ctx.Done():
    case <-doneCh:
    }
    select {
    case err = <-errCh:
        if err != nil {
            return
        }
    default:
    }
    select {
    case payload = <-payloadCh:
    default:
    }
    return
}

func (d *DexconApp) preparePayload(ctx context.Context, position coreTypes.Position) (
    payload []byte, err error) {
    d.chainRLock(position.ChainID)
    defer d.chainRUnlock(position.ChainID)
    select {
    // This case will hit if previous RLock took too much time.
    case <-ctx.Done():
        return
    default:
    }

    if position.Round > 0 {
        // If round chain number changed but new round is not delivered yet, payload must be nil.
        previousNumChains := d.gov.Configuration(position.Round - 1).NumChains
        currentNumChains := d.gov.Configuration(position.Round).NumChains
        if previousNumChains != currentNumChains {
            deliveredRound, err := rawdb.ReadLastRoundNumber(d.chainDB)
            if err != nil {
                panic(fmt.Errorf("read current round error: %v", err))
            }

            if deliveredRound < position.Round {
                return nil, nil
            }
        }
    }

    if position.Height != 0 {
        // Check if chain block height is strictly increamental.
        chainLastHeight, ok := d.blockchain.GetChainLastConfirmedHeight(position.ChainID)
        if !ok || chainLastHeight != position.Height-1 {
            log.Debug("Previous confirmed block not exists", "current pos", position.String(),
                "prev height", chainLastHeight, "ok", ok)
            return nil, fmt.Errorf("previous block not exists")
        }
    }

    root, exist := d.chainRoot.Load(position.ChainID)
    if !exist {
        return nil, nil
    }

    currentState, err := d.blockchain.StateAt(*root.(*common.Hash))
    if err != nil {
        return nil, err
    }
    log.Debug("Prepare payload", "chain", position.ChainID, "height", position.Height)

    txsMap, err := d.txPool.Pending()
    if err != nil {
        return
    }

    chainID := new(big.Int).SetUint64(uint64(position.ChainID))
    chainNums := new(big.Int).SetUint64(uint64(d.gov.GetNumChains(position.Round)))
    blockGasLimit := new(big.Int).SetUint64(d.gov.DexconConfiguration(position.Round).BlockGasLimit)
    blockGasUsed := new(big.Int)
    allTxs := make([]*types.Transaction, 0, 3000)

addressMap:
    for address, txs := range txsMap {
        select {
        case <-ctx.Done():
            break addressMap
        default:
        }
        // TX hash need to be slot to the given chain in order to be included in the block.
        if !d.addrBelongsToChain(address, chainNums, chainID) {
            continue
        }

        balance := currentState.GetBalance(address)
        cost, exist := d.blockchain.GetCostInConfirmedBlocks(position.ChainID, address)
        if exist {
            balance = new(big.Int).Sub(balance, cost)
        }

        var expectNonce uint64
        lastConfirmedNonce, exist := d.blockchain.GetLastNonceInConfirmedBlocks(position.ChainID, address)
        if !exist {
            expectNonce = currentState.GetNonce(address)
        } else {
            expectNonce = lastConfirmedNonce + 1
        }

        if len(txs) == 0 {
            continue
        }

        firstNonce := txs[0].Nonce()
        startIndex := int(expectNonce - firstNonce)

        // Warning: the pending tx will also affect by syncing, so startIndex maybe negative
        for i := startIndex; i >= 0 && i < len(txs); i++ {
            tx := txs[i]
            intrGas, err := core.IntrinsicGas(tx.Data(), tx.To() == nil, true)
            if err != nil {
                log.Error("Failed to calculate intrinsic gas", "error", err)
                return nil, fmt.Errorf("calculate intrinsic gas error: %v", err)
            }
            if tx.Gas() < intrGas {
                log.Error("Intrinsic gas too low", "txHash", tx.Hash().String())
                break
            }

            balance = new(big.Int).Sub(balance, tx.Cost())
            if balance.Cmp(big.NewInt(0)) < 0 {
                log.Warn("Insufficient funds for gas * price + value", "txHash", tx.Hash().String())
                break
            }

            blockGasUsed = new(big.Int).Add(blockGasUsed, big.NewInt(int64(tx.Gas())))
            if blockGasUsed.Cmp(blockGasLimit) > 0 {
                break addressMap
            }

            allTxs = append(allTxs, tx)
        }
    }

    return rlp.EncodeToBytes(&allTxs)
}

// PrepareWitness will return the witness data no lower than consensusHeight.
func (d *DexconApp) PrepareWitness(consensusHeight uint64) (witness coreTypes.Witness, err error) {
    var witnessBlock *types.Block
    if d.blockchain.CurrentBlock().NumberU64() >= consensusHeight {
        witnessBlock = d.blockchain.CurrentBlock()
    } else {
        log.Error("Current height too low", "lastPendingHeight", d.blockchain.CurrentBlock().NumberU64(),
            "consensusHeight", consensusHeight)
        return witness, fmt.Errorf("current height < consensus height")
    }

    witnessData, err := rlp.EncodeToBytes(witnessBlock.Hash())
    if err != nil {
        return
    }

    return coreTypes.Witness{
        Height: witnessBlock.NumberU64(),
        Data:   witnessData,
    }, nil
}

// VerifyBlock verifies if the payloads are valid.
func (d *DexconApp) VerifyBlock(block *coreTypes.Block) coreTypes.BlockVerifyStatus {
    var witnessBlockHash common.Hash
    err := rlp.DecodeBytes(block.Witness.Data, &witnessBlockHash)
    if err != nil {
        log.Error("Failed to RLP decode witness data", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    // Validate witness height.
    if d.blockchain.CurrentBlock().NumberU64() < block.Witness.Height {
        log.Debug("Current height < witness height")
        return coreTypes.VerifyRetryLater
    }

    b := d.blockchain.GetBlockByNumber(block.Witness.Height)
    if b == nil {
        log.Error("Can not get block by height", "height", block.Witness.Height)
        return coreTypes.VerifyInvalidBlock
    }

    if b.Hash() != witnessBlockHash {
        log.Error("Witness block hash not match",
            "expect", b.Hash().String(), "got", witnessBlockHash.String())
        return coreTypes.VerifyInvalidBlock
    }

    _, err = d.blockchain.StateAt(b.Root())
    if err != nil {
        log.Error("Get state by root %v error: %v", b.Root(), err)
        return coreTypes.VerifyInvalidBlock
    }

    d.chainRLock(block.Position.ChainID)
    defer d.chainRUnlock(block.Position.ChainID)

    if block.Position.Height != 0 {
        // Check if target block is the next height to be verified, we can only
        // verify the next block in a given chain.
        chainLastHeight, ok := d.blockchain.GetChainLastConfirmedHeight(block.Position.ChainID)
        if !ok || chainLastHeight != block.Position.Height-1 {
            log.Debug("Previous confirmed block not exists", "current pos", block.Position.String(),
                "prev height", chainLastHeight, "ok", ok)
            return coreTypes.VerifyRetryLater
        }
    }

    if block.Position.Round > 0 {
        // If round chain number changed but new round is not delivered yet, payload must be nil.
        previousNumChains := d.gov.Configuration(block.Position.Round - 1).NumChains
        currentNumChains := d.gov.Configuration(block.Position.Round).NumChains
        if previousNumChains != currentNumChains {
            deliveredRound, err := rawdb.ReadLastRoundNumber(d.chainDB)
            if err != nil {
                panic(fmt.Errorf("read current round error: %v", err))
            }

            if deliveredRound < block.Position.Round {
                if len(block.Payload) > 0 {
                    return coreTypes.VerifyInvalidBlock
                }

                return coreTypes.VerifyOK
            }
        }
    }

    // Get latest state with current chain.
    root, exist := d.chainRoot.Load(block.Position.ChainID)
    if !exist {
        return coreTypes.VerifyRetryLater
    }

    currentState, err := d.blockchain.StateAt(*root.(*common.Hash))
    log.Debug("Verify block", "chain", block.Position.ChainID, "height", block.Position.Height)
    if err != nil {
        log.Debug("Invalid state root", "root", *root.(*common.Hash), "err", err)
        return coreTypes.VerifyInvalidBlock
    }

    var transactions types.Transactions
    if len(block.Payload) == 0 {
        return coreTypes.VerifyOK
    }
    err = rlp.DecodeBytes(block.Payload, &transactions)
    if err != nil {
        log.Error("Payload rlp decode", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    _, err = types.GlobalSigCache.Add(types.NewEIP155Signer(d.blockchain.Config().ChainID), transactions)
    if err != nil {
        log.Error("Failed to calculate sender", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    addressNonce, err := d.validateNonce(transactions)
    if err != nil {
        log.Error("Validate nonce failed", "error", err)
        return coreTypes.VerifyInvalidBlock
    }
    if !d.validateGasPrice(transactions, block.Position.Round) {
        log.Error("Validate gas price failed")
        return coreTypes.VerifyInvalidBlock
    }

    // Check if nonce is strictly increasing for every address.
    chainID := big.NewInt(int64(block.Position.ChainID))
    chainNums := big.NewInt(int64(d.gov.GetNumChains(block.Position.Round)))

    for address, firstNonce := range addressNonce {
        if !d.addrBelongsToChain(address, chainNums, chainID) {
            log.Error("Address does not belong to given chain ID", "address", address, "chainD", chainID)
            return coreTypes.VerifyInvalidBlock
        }

        var expectNonce uint64
        lastConfirmedNonce, exist := d.blockchain.GetLastNonceInConfirmedBlocks(block.Position.ChainID, address)
        if exist {
            expectNonce = lastConfirmedNonce + 1
        } else {
            expectNonce = currentState.GetNonce(address)
        }

        if expectNonce != firstNonce {
            log.Error("Nonce check error", "expect", expectNonce, "firstNonce", firstNonce)
            return coreTypes.VerifyInvalidBlock
        }
    }

    // Calculate balance in last state (including pending state).
    addressesBalance := map[common.Address]*big.Int{}
    for address := range addressNonce {
        cost, exist := d.blockchain.GetCostInConfirmedBlocks(block.Position.ChainID, address)
        if exist {
            addressesBalance[address] = new(big.Int).Sub(currentState.GetBalance(address), cost)
        } else {
            addressesBalance[address] = currentState.GetBalance(address)
        }
    }

    // Validate if balance is enough for TXs in this block.
    blockGasLimit := new(big.Int).SetUint64(d.gov.DexconConfiguration(block.Position.Round).BlockGasLimit)
    blockGasUsed := new(big.Int)

    for _, tx := range transactions {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            log.Error("Failed to convert tx to message", "error", err)
            return coreTypes.VerifyInvalidBlock
        }
        balance := addressesBalance[msg.From()]
        intrGas, err := core.IntrinsicGas(msg.Data(), msg.To() == nil, true)
        if err != nil {
            log.Error("Failed to calculate intrinsic gas", "err", err)
            return coreTypes.VerifyInvalidBlock
        }
        if tx.Gas() < intrGas {
            log.Error("Intrinsic gas too low", "txHash", tx.Hash().String(), "intrinsic", intrGas, "gas", tx.Gas())
            return coreTypes.VerifyInvalidBlock
        }

        balance = new(big.Int).Sub(balance, tx.Cost())
        if balance.Cmp(big.NewInt(0)) < 0 {
            log.Error("Insufficient funds for gas * price + value", "txHash", tx.Hash().String())
            return coreTypes.VerifyInvalidBlock
        }

        blockGasUsed = new(big.Int).Add(blockGasUsed, new(big.Int).SetUint64(tx.Gas()))
        if blockGasUsed.Cmp(blockGasLimit) > 0 {
            log.Error("Reach block gas limit", "gasUsed", blockGasUsed)
            return coreTypes.VerifyInvalidBlock
        }
        addressesBalance[msg.From()] = balance
    }

    return coreTypes.VerifyOK
}

// BlockDelivered is called when a block is add to the compaction chain.
func (d *DexconApp) BlockDelivered(
    blockHash coreCommon.Hash,
    blockPosition coreTypes.Position,
    result coreTypes.FinalizationResult) {

    log.Debug("DexconApp block deliver", "height", result.Height, "hash", blockHash, "position", blockPosition.String())
    defer log.Debug("DexconApp block delivered", "height", result.Height, "hash", blockHash, "position", blockPosition.String())

    chainID := blockPosition.ChainID
    d.chainLock(chainID)
    defer d.chainUnlock(chainID)

    block, txs := d.blockchain.GetConfirmedBlockByHash(chainID, blockHash)
    if block == nil {
        panic("Can not get confirmed block")
    }

    block.Payload = nil
    block.Finalization = result
    dexconMeta, err := rlp.EncodeToBytes(block)
    if err != nil {
        panic(err)
    }

    newBlock := types.NewBlock(&types.Header{
        Number:     new(big.Int).SetUint64(result.Height),
        Time:       big.NewInt(result.Timestamp.UnixNano() / 1000000),
        Coinbase:   common.BytesToAddress(block.ProposerID.Bytes()),
        GasLimit:   d.gov.DexconConfiguration(block.Position.Round).BlockGasLimit,
        Difficulty: big.NewInt(1),
        Round:      block.Position.Round,
        DexconMeta: dexconMeta,
        Randomness: result.Randomness,
    }, txs, nil, nil)

    h := d.blockchain.CurrentBlock().NumberU64() + 1
    var root *common.Hash
    if block.IsEmpty() {
        root, err = d.blockchain.ProcessEmptyBlock(newBlock)
        if err != nil {
            log.Error("Failed to process empty block", "error", err)
            panic(err)
        }
    } else {
        root, err = d.blockchain.ProcessBlock(newBlock, &block.Witness)
        if err != nil {
            log.Error("Failed to process pending block", "error", err)
            panic(err)
        }
    }
    d.chainRoot.Store(chainID, root)

    d.blockchain.RemoveConfirmedBlock(chainID, blockHash)

    // New blocks are finalized, notify other components.
    newHeight := d.blockchain.CurrentBlock().NumberU64()
    for h <= newHeight {
        b := d.blockchain.GetBlockByNumber(h)
        go d.finalizedBlockFeed.Send(core.NewFinalizedBlockEvent{b})
        log.Debug("Send new finalized block event", "number", h)
        h++
    }
}

// BlockConfirmed is called when a block is confirmed and added to lattice.
func (d *DexconApp) BlockConfirmed(block coreTypes.Block) {
    d.chainLock(block.Position.ChainID)
    defer d.chainUnlock(block.Position.ChainID)

    log.Debug("DexconApp block confirmed", "block", block.String())
    if err := d.blockchain.AddConfirmedBlock(&block); err != nil {
        panic(err)
    }
}

func (d *DexconApp) SubscribeNewFinalizedBlockEvent(
    ch chan<- core.NewFinalizedBlockEvent) event.Subscription {
    return d.scope.Track(d.finalizedBlockFeed.Subscribe(ch))
}

func (d *DexconApp) Stop() {
    d.scope.Close()
}