1 files changed, 219 insertions, 0 deletions
diff --git a/ethchain/transaction_pool.go b/ethchain/transaction_pool.go
new file mode 100644
index 000000000..c2d65a2a7
--- /dev/null
+++ b/ethchain/transaction_pool.go
@@ -0,0 +1,219 @@
+package ethchain
+
+import (
+	"bytes"
+	"container/list"
+	"errors"
+	"fmt"
+	"github.com/ethereum/eth-go/ethutil"
+	"github.com/ethereum/eth-go/ethwire"
+	"log"
+	"math/big"
+	"sync"
+)
+
+const (
+	txPoolQueueSize = 50
+)
+
+type TxPoolHook chan *Transaction
+
+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 PublicSpeaker interface {
+	Broadcast(msgType ethwire.MsgType, data []interface{})
+}
+
+// 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 {
+	//server *Server
+	Speaker PublicSpeaker
+	// 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
+
+	BlockManager *BlockManager
+
+	Hook TxPoolHook
+}
+
+func NewTxPool() *TxPool {
+	return &TxPool{
+		//server:    s,
+		mutex:     sync.Mutex{},
+		pool:      list.New(),
+		queueChan: make(chan *Transaction, txPoolQueueSize),
+		quit:      make(chan bool),
+	}
+}
+
+// Blocking function. Don't use directly. Use QueueTransaction instead
+func (pool *TxPool) addTransaction(tx *Transaction) {
+	pool.mutex.Lock()
+	pool.pool.PushBack(tx)
+	pool.mutex.Unlock()
+
+	// Broadcast the transaction to the rest of the peers
+	pool.Speaker.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, block *Block) (err error) {
+	log.Printf("[TXPL] Processing Tx %x\n", tx.Hash())
+
+	defer func() {
+		if r := recover(); r != nil {
+			log.Println(r)
+			err = fmt.Errorf("%v", r)
+		}
+	}()
+	// Get the sender
+	sender := block.GetAddr(tx.Sender())
+
+	// 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, new(big.Int).Mul(TxFee, TxFeeRat))
+	if sender.Amount.Cmp(totAmount) < 0 {
+		return errors.New("Insufficient amount in sender's account")
+	}
+
+	if sender.Nonce != tx.Nonce {
+		if ethutil.Config.Debug {
+			return fmt.Errorf("Invalid nonce %d(%d) continueing anyway", tx.Nonce, sender.Nonce)
+		} else {
+			return fmt.Errorf("Invalid nonce %d(%d)", tx.Nonce, sender.Nonce)
+		}
+	}
+
+	// Subtract the amount from the senders account
+	sender.Amount.Sub(sender.Amount, totAmount)
+	sender.Nonce += 1
+
+	// Get the receiver
+	receiver := block.GetAddr(tx.Recipient)
+	// Add the amount to receivers account which should conclude this transaction
+	receiver.Amount.Add(receiver.Amount, tx.Value)
+
+	block.UpdateAddr(tx.Sender(), sender)
+	block.UpdateAddr(tx.Recipient, receiver)
+
+	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.BlockManager.BlockChain().CurrentBlock
+	// Something has gone horribly wrong if this happens
+	if block == nil {
+		return errors.New("No last block on the block chain")
+	}
+
+	// Get the sender
+	sender := block.GetAddr(tx.Sender())
+
+	totAmount := new(big.Int).Add(tx.Value, new(big.Int).Mul(TxFee, TxFeeRat))
+	// 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("Insufficient amount in sender's (%x) account", tx.Sender())
+	}
+
+	// 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 {
+				if ethutil.Config.Debug {
+					log.Println("Validating Tx failed", err)
+				}
+			} else {
+				// Call blocking version. At this point it
+				// doesn't matter since this is a goroutine
+				pool.addTransaction(tx)
+
+				if pool.Hook != nil {
+					pool.Hook <- tx
+				}
+			}
+		case <-pool.quit:
+			break out
+		}
+	}
+}
+
+func (pool *TxPool) QueueTransaction(tx *Transaction) {
+	pool.queueChan <- tx
+}
+
+func (pool *TxPool) Flush() []*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() {
+		if tx, ok := e.Value.(*Transaction); ok {
+			txList[i] = tx
+		}
+
+		i++
+	}
+
+	// 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() {
+	log.Println("[TXP] Stopping...")
+
+	close(pool.quit)
+
+	pool.Flush()
+}