path: root/ethchain/transaction_pool.go

package ethchain

import (
    "bytes"
    "container/list"
    "fmt"
    "github.com/ethereum/eth-go/ethlog"
    "github.com/ethereum/eth-go/ethwire"
    "math/big"
    "sync"
)

var txplogger = ethlog.NewLogger("TXP")

const (
    txPoolQueueSize = 50
)

type TxPoolHook chan *Transaction
type TxMsgTy byte

const (
    TxPre = iota
    TxPost
    minGasPrice = 1000000
)

type TxMsg struct {
    Tx   *Transaction
    Type TxMsgTy
}

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{
        //server:    s,
        mutex:     sync.Mutex{},
        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(ethwire.MsgTxTy, []interface{}{tx.RlpData()})
}

/*
// Process transaction validates the Tx and processes funds from the
// sender to the recipient.
func (pool *TxPool) ProcessTransaction(tx *Transaction, state *State, toContract bool) (gas *big.Int, err error) {
    fmt.Printf("state root before update %x\n", state.Root())
    defer func() {
        if r := recover(); r != nil {
            txplogger.Infoln(r)
            err = fmt.Errorf("%v", r)
        }
    }()

    gas = new(big.Int)
    addGas := func(g *big.Int) { gas.Add(gas, g) }
    addGas(GasTx)

    // Get the sender
    sender := state.GetAccount(tx.Sender())

    if sender.Nonce != tx.Nonce {
        err = NonceError(tx.Nonce, sender.Nonce)
        return
    }

    sender.Nonce += 1
    defer func() {
        //state.UpdateStateObject(sender)
        // Notify all subscribers
        pool.Ethereum.Reactor().Post("newTx:post", tx)
    }()

    txTotalBytes := big.NewInt(int64(len(tx.Data)))
    txTotalBytes.Div(txTotalBytes, ethutil.Big32)
    addGas(new(big.Int).Mul(txTotalBytes, GasSStore))

    rGas := new(big.Int).Set(gas)
    rGas.Mul(gas, tx.GasPrice)

    // Make sure there's enough in the sender's account. Having insufficient
    // funds won't invalidate this transaction but simple ignores it.
    totAmount := new(big.Int).Add(tx.Value, rGas)
    if sender.Amount.Cmp(totAmount) < 0 {
        err = fmt.Errorf("[TXPL] Insufficient amount in sender's (%x) account", tx.Sender())
        return
    }
    state.UpdateStateObject(sender)
    fmt.Printf("state root after sender update %x\n", state.Root())

    // Get the receiver
    receiver := state.GetAccount(tx.Recipient)

    // Send Tx to self
    if bytes.Compare(tx.Recipient, tx.Sender()) == 0 {
        // Subtract the fee
        sender.SubAmount(rGas)
    } else {
        // Subtract the amount from the senders account
        sender.SubAmount(totAmount)

        // Add the amount to receivers account which should conclude this transaction
        receiver.AddAmount(tx.Value)

        state.UpdateStateObject(receiver)
        fmt.Printf("state root after receiver update %x\n", state.Root())
    }

    txplogger.Infof("[TXPL] Processed Tx %x\n", tx.Hash())

    return
}
*/

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

    // Get the sender
    //sender := pool.Ethereum.StateManager().procState.GetAccount(tx.Sender())
    sender := pool.Ethereum.StateManager().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.Amount.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 (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)

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

                // Notify the subscribers
                pool.Ethereum.Reactor().Post("newTx:pre", 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) {
    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 (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")
}