path: root/chain/transaction_pool.go

package chain

import (
    "bytes"
    "container/list"
    "fmt"
    "math/big"
    "sync"

    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/state"
    "github.com/ethereum/go-ethereum/wire"
)

var txplogger = logger.NewLogger("TXP")

const txPoolQueueSize = 50

type TxPoolHook chan *Transaction
type TxMsgTy byte

const (
    minGasPrice = 1000000
)

var MinGasPrice = big.NewInt(10000000000000)

type TxMsg struct {
    Tx   *Transaction
    Type TxMsgTy
}

func EachTx(pool *list.List, it func(*Transaction, *list.Element) bool) {
    for e := pool.Front(); e != nil; e = e.Next() {
        if it(e.Value.(*Transaction), e) {
            break
        }
    }
}

func FindTx(pool *list.List, finder func(*Transaction, *list.Element) bool) *Transaction {
    for e := pool.Front(); e != nil; e = e.Next() {
        if tx, ok := e.Value.(*Transaction); ok {
            if finder(tx, e) {
                return tx
            }
        }
    }

    return nil
}

type TxProcessor interface {
    ProcessTransaction(tx *Transaction)
}

// The tx pool a thread safe transaction pool handler. In order to
// guarantee a non blocking pool we use a queue channel which can be
// independently read without needing access to the actual pool. If the
// pool is being drained or synced for whatever reason the transactions
// will simple queue up and handled when the mutex is freed.
type TxPool struct {
    Ethereum EthManager
    // The mutex for accessing the Tx pool.
    mutex sync.Mutex
    // Queueing channel for reading and writing incoming
    // transactions to
    queueChan chan *Transaction
    // Quiting channel
    quit chan bool
    // The actual pool
    pool *list.List

    SecondaryProcessor TxProcessor

    subscribers []chan TxMsg
}

func NewTxPool(ethereum EthManager) *TxPool {
    return &TxPool{
        pool:      list.New(),
        queueChan: make(chan *Transaction, txPoolQueueSize),
        quit:      make(chan bool),
        Ethereum:  ethereum,
    }
}

// Blocking function. Don't use directly. Use QueueTransaction instead
func (pool *TxPool) addTransaction(tx *Transaction) {
    pool.mutex.Lock()
    defer pool.mutex.Unlock()

    pool.pool.PushBack(tx)

    // Broadcast the transaction to the rest of the peers
    pool.Ethereum.Broadcast(wire.MsgTxTy, []interface{}{tx.RlpData()})
}

func (pool *TxPool) ValidateTransaction(tx *Transaction) error {
    // Get the last block so we can retrieve the sender and receiver from
    // the merkle trie
    block := pool.Ethereum.ChainManager().CurrentBlock
    // Something has gone horribly wrong if this happens
    if block == nil {
        return fmt.Errorf("[TXPL] No last block on the block chain")
    }

    if len(tx.Recipient) != 0 && len(tx.Recipient) != 20 {
        return fmt.Errorf("[TXPL] Invalid recipient. len = %d", len(tx.Recipient))
    }

    if tx.GasPrice.Cmp(MinGasPrice) < 0 {
        return fmt.Errorf("Gas price to low. Require %v > Got %v", MinGasPrice, tx.GasPrice)
    }

    // Get the sender
    sender := pool.Ethereum.BlockManager().CurrentState().GetAccount(tx.Sender())

    totAmount := new(big.Int).Set(tx.Value)
    // Make sure there's enough in the sender's account. Having insufficient
    // funds won't invalidate this transaction but simple ignores it.
    if sender.Balance().Cmp(totAmount) < 0 {
        return fmt.Errorf("[TXPL] Insufficient amount in sender's (%x) account", tx.Sender())
    }

    if tx.IsContract() {
        if tx.GasPrice.Cmp(big.NewInt(minGasPrice)) < 0 {
            return fmt.Errorf("[TXPL] Gasprice too low, %s given should be at least %d.", tx.GasPrice, minGasPrice)
        }
    }

    // Increment the nonce making each tx valid only once to prevent replay
    // attacks

    return nil
}

func (self *TxPool) Add(tx *Transaction) error {
    hash := tx.Hash()
    foundTx := FindTx(self.pool, func(tx *Transaction, e *list.Element) bool {
        return bytes.Compare(tx.Hash(), hash) == 0
    })

    if foundTx != nil {
        return fmt.Errorf("Known transaction (%x)", hash[0:4])
    }

    err := self.ValidateTransaction(tx)
    if err != nil {
        return err
    }

    self.addTransaction(tx)

    tmp := make([]byte, 4)
    copy(tmp, tx.Recipient)

    txplogger.Debugf("(t) %x => %x (%v) %x\n", tx.Sender()[:4], tmp, tx.Value, tx.Hash())

    // Notify the subscribers
    self.Ethereum.EventMux().Post(TxPreEvent{tx})

    return nil
}

func (pool *TxPool) queueHandler() {
out:
    for {
        select {
        case tx := <-pool.queueChan:
            hash := tx.Hash()
            foundTx := FindTx(pool.pool, func(tx *Transaction, e *list.Element) bool {
                return bytes.Compare(tx.Hash(), hash) == 0
            })

            if foundTx != nil {
                break
            }

            // Validate the transaction
            err := pool.ValidateTransaction(tx)
            if err != nil {
                txplogger.Debugln("Validating Tx failed", err)
            } else {
                // Call blocking version.
                pool.addTransaction(tx)

                tmp := make([]byte, 4)
                copy(tmp, tx.Recipient)

                txplogger.Debugf("(t) %x => %x (%v) %x\n", tx.Sender()[:4], tmp, tx.Value, tx.Hash())

                // Notify the subscribers
                pool.Ethereum.EventMux().Post(TxPreEvent{tx})
            }
        case <-pool.quit:
            break out
        }
    }
}

/*
func (pool *TxPool) QueueTransaction(tx *Transaction) {
    pool.queueChan <- tx
}
*/

func (pool *TxPool) CurrentTransactions() []*Transaction {
    pool.mutex.Lock()
    defer pool.mutex.Unlock()

    txList := make([]*Transaction, pool.pool.Len())
    i := 0
    for e := pool.pool.Front(); e != nil; e = e.Next() {
        tx := e.Value.(*Transaction)

        txList[i] = tx

        i++
    }

    return txList
}

func (pool *TxPool) RemoveInvalid(state *state.State) {
    pool.mutex.Lock()
    defer pool.mutex.Unlock()

    for e := pool.pool.Front(); e != nil; e = e.Next() {
        tx := e.Value.(*Transaction)
        sender := state.GetAccount(tx.Sender())
        err := pool.ValidateTransaction(tx)
        if err != nil || sender.Nonce >= tx.Nonce {
            pool.pool.Remove(e)
        }
    }
}

func (self *TxPool) RemoveSet(txs Transactions) {
    self.mutex.Lock()
    defer self.mutex.Unlock()

    for _, tx := range txs {
        EachTx(self.pool, func(t *Transaction, element *list.Element) bool {
            if t == tx {
                self.pool.Remove(element)
                return true // To stop the loop
            }
            return false
        })
    }
}

func (pool *TxPool) Flush() []*Transaction {
    txList := pool.CurrentTransactions()

    // Recreate a new list all together
    // XXX Is this the fastest way?
    pool.pool = list.New()

    return txList
}

func (pool *TxPool) Start() {
    go pool.queueHandler()
}

func (pool *TxPool) Stop() {
    close(pool.quit)

    pool.Flush()

    txplogger.Infoln("Stopped")
}