core: fix transaction reorg issues within the tx pool

core/transaction_pool.go

@@ -138,7 +138,6 @@ func (pool *TxPool) resetState() {
 			}
 		}
 	}
-
 	// Check the queue and move transactions over to the pending if possible
 	// or remove those that have become invalid
 	pool.checkQueue()
@@ -290,17 +289,15 @@ func (pool *TxPool) addTx(hash common.Hash, addr common.Address, tx *types.Trans
 }
 
 // Add queues a single transaction in the pool if it is valid.
-func (self *TxPool) Add(tx *types.Transaction) (err error) {
+func (self *TxPool) Add(tx *types.Transaction) error {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	err = self.add(tx)
-	if err == nil {
-		// check and validate the queueue
-		self.checkQueue()
+	if err := self.add(tx); err != nil {
+		return err
 	}
-
-	return
+	self.checkQueue()
+	return nil
 }
 
 // AddTransactions attempts to queue all valid transactions in txs.
@@ -406,51 +403,55 @@ func (pool *TxPool) checkQueue() {
 		pool.resetState()
 	}
 
-	var addq txQueue
+	var promote txQueue
 	for address, txs := range pool.queue {
-		// guessed nonce is the nonce currently kept by the tx pool (pending state)
-		guessedNonce := pool.pendingState.GetNonce(address)
-		// true nonce is the nonce known by the last state
 		currentState, err := pool.currentState()
 		if err != nil {
 			glog.Errorf("could not get current state: %v", err)
 			return
 		}
-		trueNonce := currentState.GetNonce(address)
-		addq := addq[:0]
+		balance := currentState.GetBalance(address)
+
+		var (
+			guessedNonce = pool.pendingState.GetNonce(address) // nonce currently kept by the tx pool (pending state)
+			trueNonce    = currentState.GetNonce(address)      // nonce known by the last state
+		)
+		promote = promote[:0]
 		for hash, tx := range txs {
-			if tx.Nonce() < trueNonce {
-				// Drop queued transactions whose nonce is lower than
-				// the account nonce because they have been processed.
+			// Drop processed or out of fund transactions
+			if tx.Nonce() < trueNonce || balance.Cmp(tx.Cost()) < 0 {
+				if glog.V(logger.Core) {
+					glog.Infof("removed tx (%v) from pool queue: low tx nonce or out of funds\n", tx)
+				}
 				delete(txs, hash)
-			} else {
-				// Collect the remaining transactions for the next pass.
-				addq = append(addq, txQueueEntry{hash, address, tx})
-			}
-		}
-		// Find the next consecutive nonce range starting at the
-		// current account nonce.
-		sort.Sort(addq)
-		for i, e := range addq {
-			// start deleting the transactions from the queue if they exceed the limit
-			if i > maxQueued {
-				delete(pool.queue[address], e.hash)
 				continue
 			}
-
-			if e.Nonce() > guessedNonce {
-				if len(addq)-i > maxQueued {
+			// Collect the remaining transactions for the next pass.
+			promote = append(promote, txQueueEntry{hash, address, tx})
+		}
+		// Find the next consecutive nonce range starting at the current account nonce,
+		// pushing the guessed nonce forward if we add consecutive transactions.
+		sort.Sort(promote)
+		for i, entry := range promote {
+			// If we reached a gap in the nonces, enforce transaction limit and stop
+			if entry.Nonce() > guessedNonce {
+				if len(promote)-i > maxQueued {
 					if glog.V(logger.Debug) {
-						glog.Infof("Queued tx limit exceeded for %s. Tx %s removed\n", common.PP(address[:]), common.PP(e.hash[:]))
+						glog.Infof("Queued tx limit exceeded for %s. Tx %s removed\n", common.PP(address[:]), common.PP(entry.hash[:]))
 					}
-					for j := i + maxQueued; j < len(addq); j++ {
-						delete(txs, addq[j].hash)
+					for _, drop := range promote[i+maxQueued:] {
+						delete(txs, drop.hash)
 					}
 				}
 				break
 			}
-			delete(txs, e.hash)
-			pool.addTx(e.hash, address, e.Transaction)
+			// Otherwise promote the transaction and move the guess nonce if needed
+			pool.addTx(entry.hash, address, entry.Transaction)
+			delete(txs, entry.hash)
+
+			if entry.Nonce() == guessedNonce {
+				guessedNonce++
+			}
 		}
 		// Delete the entire queue entry if it became empty.
 		if len(txs) == 0 {
@@ -460,20 +461,56 @@ func (pool *TxPool) checkQueue() {
 }
 
 // validatePool removes invalid and processed transactions from the main pool.
+// If a transaction is removed for being invalid (e.g. out of funds), all sub-
+// sequent (Still valid) transactions are moved back into the future queue. This
+// is important to prevent a drained account from DOSing the network with non
+// executable transactions.
 func (pool *TxPool) validatePool() {
 	state, err := pool.currentState()
 	if err != nil {
 		glog.V(logger.Info).Infoln("failed to get current state: %v", err)
 		return
 	}
+	balanceCache := make(map[common.Address]*big.Int)
+
+	// Clean up the pending pool, accumulating invalid nonces
+	gaps := make(map[common.Address]uint64)
+
 	for hash, tx := range pool.pending {
-		from, _ := tx.From() // err already checked
-		// perform light nonce validation
-		if state.GetNonce(from) > tx.Nonce() {
+		sender, _ := tx.From() // err already checked
+
+		// Perform light nonce and balance validation
+		balance := balanceCache[sender]
+		if balance == nil {
+			balance = state.GetBalance(sender)
+			balanceCache[sender] = balance
+		}
+		if past := state.GetNonce(sender) > tx.Nonce(); past || balance.Cmp(tx.Cost()) < 0 {
+			// Remove an already past it invalidated transaction
 			if glog.V(logger.Core) {
-				glog.Infof("removed tx (%x) from pool: low tx nonce\n", hash[:4])
+				glog.Infof("removed tx (%v) from pool: low tx nonce or out of funds\n", tx)
 			}
 			delete(pool.pending, hash)
+
+			// Track the smallest invalid nonce to postpone subsequent transactions
+			if !past {
+				if prev, ok := gaps[sender]; !ok || tx.Nonce() < prev {
+					gaps[sender] = tx.Nonce()
+				}
+			}
+		}
+	}
+	// Move all transactions after a gap back to the future queue
+	if len(gaps) > 0 {
+		for hash, tx := range pool.pending {
+			sender, _ := tx.From()
+			if gap, ok := gaps[sender]; ok && tx.Nonce() >= gap {
+				if glog.V(logger.Core) {
+					glog.Infof("postponed tx (%v) due to introduced gap\n", tx)
+				}
+				pool.queueTx(hash, tx)
+				delete(pool.pending, hash)
+			}
 		}
 	}
 }