path: root/dex/app.go

// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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-core 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-core library. If not, see
// <http://www.gnu.org/licenses/>.

package dex

import (
    "bytes"
    "github.com/dexon-foundation/dexon/core/rawdb"
    "math/big"
    "sync"
    "time"

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

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core"
    "github.com/dexon-foundation/dexon/core/state"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/core/vm"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/rlp"
)

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

    notifyChan map[uint64]*notify
    mutex      *sync.Mutex
}

type notify struct {
    results []chan bool
}

func NewDexconApp(txPool *core.TxPool, blockchain *core.BlockChain, gov *DexconGovernance, chainDB ethdb.Database, config *Config, vmConfig vm.Config) *DexconApp {
    return &DexconApp{
        txPool:     txPool,
        blockchain: blockchain,
        gov:        gov,
        chainDB:    chainDB,
        config:     config,
        vmConfig:   vmConfig,
        notifyChan: make(map[uint64]*notify),
        mutex:      &sync.Mutex{},
    }
}

func (d *DexconApp) addNotify(height uint64) <-chan bool {
    d.mutex.Lock()
    defer d.mutex.Unlock()
    result := make(chan bool)
    if n, exist := d.notifyChan[height]; exist {
        n.results = append(n.results, result)
    } else {
        d.notifyChan[height] = &notify{}
        d.notifyChan[height].results = append(d.notifyChan[height].results, result)
    }
    return result
}

func (d *DexconApp) notify(height uint64) {
    d.mutex.Lock()
    defer d.mutex.Unlock()
    for h, n := range d.notifyChan {
        if height >= h {
            for _, ch := range n.results {
                ch <- true
            }
            delete(d.notifyChan, h)
        }
    }
}

// PreparePayload is called when consensus core is preparing payload for block.
func (d *DexconApp) PreparePayload(position coreTypes.Position) (payload []byte) {
    txsMap, err := d.txPool.Pending()
    if err != nil {
        return
    }

    currentBlock := d.blockchain.CurrentBlock()
    gasLimit := core.CalcGasLimit(currentBlock, d.config.GasFloor, d.config.GasCeil)
    gp := new(core.GasPool).AddGas(gasLimit)

    stateDB, err := state.New(currentBlock.Root(), state.NewDatabase(d.chainDB))
    if err != nil {
        return
    }

    chainID := new(big.Int).SetUint64(uint64(position.ChainID))
    chainSize := new(big.Int).SetUint64(uint64(d.gov.Configuration(position.Round).NumChains))
    var allTxs types.Transactions
    var gasUsed uint64
    for addr, txs := range txsMap {
        addrModChainSize := new(big.Int)
        if addrModChainSize.Mod(addr.Big(), chainSize).Cmp(chainID) != 0 {
            continue
        }

        for _, tx := range txs {
            core.ApplyTransaction(d.blockchain.Config(), d.blockchain, nil, gp, stateDB, currentBlock.Header(), tx, &gasUsed, d.vmConfig)
            if gasUsed > gasLimit {
                break
            }
            allTxs = append(allTxs, tx)
        }
    }
    payload, err = rlp.EncodeToBytes(&allTxs)
    if err != nil {
        // do something
        return
    }

    return
}

type WitnessData struct {
    Root        common.Hash
    TxHash      common.Hash
    ReceiptHash common.Hash
}

func (d *DexconApp) PrepareWitness(consensusHeight uint64) (witness coreTypes.Witness) {
    var currentBlock *types.Block
    currentBlock = d.blockchain.CurrentBlock()
    if currentBlock.NumberU64() < consensusHeight {
        // wait notification
        if <-d.addNotify(consensusHeight) {
            currentBlock = d.blockchain.CurrentBlock()
        } else {
            // do something if notify fail
        }
    }

    witnessData, err := rlp.EncodeToBytes(&WitnessData{
        Root:        currentBlock.Root(),
        TxHash:      currentBlock.TxHash(),
        ReceiptHash: currentBlock.ReceiptHash(),
    })
    if err != nil {
        return
    }

    return coreTypes.Witness{
        Timestamp: time.Unix(currentBlock.Time().Int64(), 0),
        Height:    currentBlock.NumberU64(),
        Data:      witnessData,
    }
}

// VerifyBlock verifies if the payloads are valid.
func (d *DexconApp) VerifyBlock(block *coreTypes.Block) bool {
    // decode payload to transactions
    var transactions types.Transactions
    err := rlp.Decode(bytes.NewReader(block.Payload), &transactions)
    if err != nil {
        return false
    }

    // verify transactions
    for _, transaction := range transactions {
        if d.txPool.ValidateTx(transaction, false) != nil {
            return false
        }
    }

    currentBlock := d.blockchain.CurrentBlock()
    gasLimit := core.CalcGasLimit(currentBlock, d.config.GasFloor, d.config.GasCeil)
    gp := new(core.GasPool).AddGas(gasLimit)

    stateDB, err := state.New(currentBlock.Root(), state.NewDatabase(d.chainDB))
    if err != nil {
        return false
    }

    var gasUsed uint64
    for _, tx := range transactions {
        core.ApplyTransaction(d.blockchain.Config(), d.blockchain, nil, gp, stateDB, currentBlock.Header(), tx, &gasUsed, d.vmConfig)
    }

    if gasUsed > gasLimit+d.config.GasLimitTolerance {
        return false
    }

    witnessData := WitnessData{}
    err = rlp.Decode(bytes.NewReader(block.Witness.Data), &witnessData)
    if err != nil {
        return false
    }

    witnessBlock := d.blockchain.GetBlockByNumber(block.Witness.Height)
    if witnessBlock == nil {
        return false
    } else if witnessBlock.Root() != witnessData.Root {
        // invalid state root of witness data
        return false
    } else if witnessBlock.ReceiptHash() != witnessData.ReceiptHash {
        // invalid receipt root of witness data
        return false
    } else if witnessBlock.TxHash() != witnessData.TxHash {
        // invalid tx root of witness data
        return false
    }

    for _, transaction := range witnessBlock.Transactions() {
        tx, _, _, _ := rawdb.ReadTransaction(d.chainDB, transaction.Hash())
        if tx == nil {
            return false
        }
    }

    return true
}

// BlockDelivered is called when a block is add to the compaction chain.
func (d *DexconApp) BlockDelivered(block coreTypes.Block) {
    var transactions types.Transactions
    err := rlp.Decode(bytes.NewReader(block.Payload), &transactions)
    if err != nil {
        return
    }

    _, err = d.blockchain.InsertChain(
        []*types.Block{types.NewBlock(&types.Header{
            ParentHash: common.Hash(block.ParentHash),
            Number:     new(big.Int).SetUint64(block.ConsensusHeight),
            Time:       new(big.Int).SetInt64(block.ConsensusTimestamp.Unix()),
            TxHash:     types.DeriveSha(transactions),
            Coinbase:   common.BytesToAddress(block.ProposerID.Hash[:]),
        }, transactions, nil, nil)})
    if err != nil {
        // do something
        return
    }

    d.notify(block.ConsensusHeight)
}