core, eth, internal, miner: optimize txpool for quick ops

6 files changed, 751 insertions, 401 deletions

diff --git a/core/tx_list.go b/core/tx_list.go
new file mode 100644
index 000000000..e30fee38f
--- /dev/null
+++ b/core/tx_list.go
@@ -0,0 +1,331 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"container/heap"
+	"math"
+	"math/big"
+	"sort"
+
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+// nonceHeap is a heap.Interface implementation over 64bit unsigned integers for
+// retrieving sorted transactions from the possibly gapped future queue.
+type nonceHeap []uint64
+
+func (h nonceHeap) Len() int           { return len(h) }
+func (h nonceHeap) Less(i, j int) bool { return h[i] < h[j] }
+func (h nonceHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+
+func (h *nonceHeap) Push(x interface{}) {
+	*h = append(*h, x.(uint64))
+}
+
+func (h *nonceHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+// txList is a "list" of transactions belonging to an account, sorted by account
+// nonce. The same type can be used both for storing contiguous transactions for
+// the executable/pending queue; and for storing gapped transactions for the non-
+// executable/future queue, with minor behavoiral changes.
+type txList struct {
+	strict bool                          // Whether nonces are strictly continuous or not
+	items  map[uint64]*types.Transaction // Hash map storing the transaction data
+	cache  types.Transactions            // cache of the transactions already sorted
+
+	first uint64     // Nonce of the lowest stored transaction (strict mode)
+	last  uint64     // Nonce of the highest stored transaction (strict mode)
+	index *nonceHeap // Heap of nonces of all teh stored transactions (non-strict mode)
+
+	costcap *big.Int // Price of the highest costing transaction (reset only if exceeds balance)
+}
+
+// newTxList create a new transaction list for maintaining nonce-indexable fast,
+// gapped, sortable transaction lists.
+func newTxList(strict bool) *txList {
+	return &txList{
+		strict:  strict,
+		items:   make(map[uint64]*types.Transaction),
+		first:   math.MaxUint64,
+		index:   &nonceHeap{},
+		costcap: new(big.Int),
+	}
+}
+
+// Add tries to inserts a new transaction into the list, returning whether the
+// transaction was acceped, and if yes, any previous transaction it replaced.
+//
+// In case of strict lists (contiguous nonces) the nonce boundaries are updated
+// appropriately with the new transaction. Otherwise (gapped nonces) the heap of
+// nonces is expanded with the new transaction.
+func (l *txList) Add(tx *types.Transaction) (bool, *types.Transaction) {
+	// If an existing transaction is better, discard new one
+	nonce := tx.Nonce()
+
+	old, ok := l.items[nonce]
+	if ok && old.GasPrice().Cmp(tx.GasPrice()) >= 0 {
+		return false, nil
+	}
+	// Otherwise insert the transaction and replace any previous one
+	l.items[nonce] = tx
+	if cost := tx.Cost(); l.costcap.Cmp(cost) < 0 {
+		l.costcap = cost
+	}
+	if l.strict {
+		// In strict mode, maintain the nonce sequence boundaries
+		if nonce < l.first {
+			l.first = nonce
+		}
+		if nonce > l.last {
+			l.last = nonce
+		}
+	} else {
+		// In gapped mode, maintain the nonce heap
+		heap.Push(l.index, nonce)
+	}
+	l.cache = nil
+
+	return true, old
+}
+
+// Forward removes all transactions from the list with a nonce lower than the
+// provided threshold. Every removed transaction is returned for any post-removal
+// maintenance.
+func (l *txList) Forward(threshold uint64) types.Transactions {
+	var removed types.Transactions
+
+	if l.strict {
+		// In strict mode, push the lowest nonce forward to the threshold
+		for l.first < threshold {
+			if tx, ok := l.items[l.first]; ok {
+				removed = append(removed, tx)
+			}
+			delete(l.items, l.first)
+			l.first++
+		}
+		if l.first > l.last {
+			l.last = l.first
+		}
+	} else {
+		// In gapped mode, pop off heap items until the threshold is reached
+		for l.index.Len() > 0 && (*l.index)[0] < threshold {
+			nonce := heap.Pop(l.index).(uint64)
+			removed = append(removed, l.items[nonce])
+			delete(l.items, nonce)
+		}
+	}
+	l.cache = nil
+
+	return removed
+}
+
+// Filter removes all transactions from the list with a cost higher than the
+// provided threshold. Every removed transaction is returned for any post-removal
+// maintenance. Strict-mode invalidated transactions are also returned.
+//
+// This method uses the cached costcap to quickly decide if there's even a point
+// in calculating all the costs or if the balance covers all. If the threshold is
+// loewr than the costcap, the costcap will be reset to a new high after removing
+// expensive the too transactions.
+func (l *txList) Filter(threshold *big.Int) (types.Transactions, types.Transactions) {
+	// If all transactions are blow the threshold, short circuit
+	if l.costcap.Cmp(threshold) <= 0 {
+		return nil, nil
+	}
+	l.costcap = new(big.Int).Set(threshold) // Lower the cap to the threshold
+
+	// Gather all the transactions needing deletion
+	var removed types.Transactions
+	for _, tx := range l.items {
+		if cost := tx.Cost(); cost.Cmp(threshold) > 0 {
+			removed = append(removed, tx)
+			delete(l.items, tx.Nonce())
+		}
+	}
+	// Readjust the nonce boundaries/indexes and gather invalidate tranactions
+	var invalids types.Transactions
+	if l.strict {
+		// In strict mode iterate find the first gap and invalidate everything after it
+		for i := l.first; i <= l.last; i++ {
+			if _, ok := l.items[i]; !ok {
+				// Gap found, invalidate all subsequent transactions
+				for j := i + 1; j <= l.last; j++ {
+					if tx, ok := l.items[j]; ok {
+						invalids = append(invalids, tx)
+						delete(l.items, j)
+					}
+				}
+				// Reduce the highest transaction nonce and return
+				l.last = i - 1
+				break
+			}
+		}
+	} else {
+		// In gapped mode no transactions are invalid, but the heap is ruined
+		l.index = &nonceHeap{}
+		for nonce, _ := range l.items {
+			*l.index = append(*l.index, nonce)
+		}
+		heap.Init(l.index)
+	}
+	l.cache = nil
+
+	return removed, invalids
+}
+
+// Cap places a hard limit on the number of items, returning all transactions
+// exceeding tht limit.
+func (l *txList) Cap(threshold int) types.Transactions {
+	// Short circuit if the number of items is under the limit
+	if len(l.items) < threshold {
+		return nil
+	}
+	// Otherwise gather and drop the highest nonce'd transactions
+	var drops types.Transactions
+
+	if l.strict {
+		// In strict mode, just gather top down from last to first
+		for len(l.items) > threshold {
+			if tx, ok := l.items[l.last]; ok {
+				drops = append(drops, tx)
+				delete(l.items, l.last)
+				l.last--
+			}
+		}
+	} else {
+		// In gapped mode it's expensive: we need to sort and drop like that
+		sort.Sort(*l.index)
+		for size := len(l.items); size > threshold; size-- {
+			drops = append(drops, l.items[(*l.index)[size-1]])
+			delete(l.items, (*l.index)[size-1])
+			*l.index = (*l.index)[:size-1]
+		}
+		heap.Init(l.index)
+	}
+	l.cache = nil
+
+	return drops
+}
+
+// Remove deletes a transaction from the maintained list, returning whether the
+// transaction was found, and also returning any transaction invalidated due to
+// the deletion (strict mode only).
+func (l *txList) Remove(tx *types.Transaction) (bool, types.Transactions) {
+	nonce := tx.Nonce()
+	if _, ok := l.items[nonce]; ok {
+		// Remove the item and invalidate the sorted cache
+		delete(l.items, nonce)
+		l.cache = nil
+
+		// Remove all invalidated transactions (strict mode only!)
+		invalids := make(types.Transactions, 0, l.last-nonce)
+		if l.strict {
+			for i := nonce + 1; i <= l.last; i++ {
+				invalids = append(invalids, l.items[i])
+				delete(l.items, i)
+			}
+			l.last = nonce - 1
+		} else {
+			// In gapped mode, remove the nonce from the index but honour the heap
+			for i := 0; i < l.index.Len(); i++ {
+				if (*l.index)[i] == nonce {
+					heap.Remove(l.index, i)
+					break
+				}
+			}
+		}
+		// Figure out the new highest nonce
+		return true, invalids
+	}
+	return false, nil
+}
+
+// Ready retrieves a sequentially increasing list of transactions starting at the
+// provided nonce that is ready for processing. The returned transactions will be
+// removed from the list.
+//
+// Note, all transactions with nonces lower that start will also be returned to
+// prevent getting into and invalid state. This is not something that should ever
+// happen but better to be self correcting than failing!
+func (l *txList) Ready(start uint64) types.Transactions {
+	var txs types.Transactions
+	if l.strict {
+		// In strict mode make sure we have valid transaction, return all contiguous
+		if l.first > start {
+			return nil
+		}
+		for {
+			if tx, ok := l.items[l.first]; ok {
+				txs = append(txs, tx)
+				delete(l.items, l.first)
+				l.first++
+				continue
+			}
+			break
+		}
+	} else {
+		// In gapped mode, check the heap start and return all contiguous
+		if l.index.Len() == 0 || (*l.index)[0] > start {
+			return nil
+		}
+		next := (*l.index)[0]
+		for l.index.Len() > 0 && (*l.index)[0] == next {
+			txs = append(txs, l.items[next])
+			delete(l.items, next)
+			heap.Pop(l.index)
+			next++
+		}
+	}
+	l.cache = nil
+
+	return txs
+}
+
+// Len returns the length of the transaction list.
+func (l *txList) Len() int {
+	return len(l.items)
+}
+
+// Empty returns whether the list of transactions is empty or not.
+func (l *txList) Empty() bool {
+	return len(l.items) == 0
+}
+
+// Flatten creates a nonce-sorted slice of transactions based on the loosely
+// sorted internal representation. The result of the sorting is cached in case
+// it's requested again before any modifications are made to the contents.
+func (l *txList) Flatten() types.Transactions {
+	// If the sorting was not cached yet, create and cache it
+	if l.cache == nil {
+		l.cache = make(types.Transactions, 0, len(l.items))
+		for _, tx := range l.items {
+			l.cache = append(l.cache, tx)
+		}
+		sort.Sort(types.TxByNonce(l.cache))
+	}
+	// Copy the cache to prevent accidental modifications
+	txs := make(types.Transactions, len(l.cache))
+	copy(txs, l.cache)
+	return txs
+}
diff --git a/core/tx_list_test.go b/core/tx_list_test.go
new file mode 100644
index 000000000..ea83ca479
--- /dev/null
+++ b/core/tx_list_test.go
@@ -0,0 +1,58 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"math/big"
+	"math/rand"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// Tests that transactions can be added to strict lists and list contents and
+// nonce boundaries are correctly maintained.
+func TestStrictTxListAdd(t *testing.T) {
+	// Generate a list of transactions to insert
+	key, _ := crypto.GenerateKey()
+
+	txs := make(types.Transactions, 1024)
+	for i := 0; i < len(txs); i++ {
+		txs[i] = transaction(uint64(i), new(big.Int), key)
+	}
+	// Insert the transactions in a random order
+	list := newTxList(true)
+	for _, v := range rand.Perm(len(txs)) {
+		list.Add(txs[v])
+	}
+	// Verify internal state
+	if list.first != 0 {
+		t.Errorf("lowest nonce mismatch: have %d, want %d", list.first, 0)
+	}
+	if int(list.last) != len(txs)-1 {
+		t.Errorf("highest nonce mismatch: have %d, want %d", list.last, len(txs)-1)
+	}
+	if len(list.items) != len(txs) {
+		t.Errorf("transaction count mismatch: have %d, want %d", len(list.items), len(txs))
+	}
+	for i, tx := range txs {
+		if list.items[tx.Nonce()] != tx {
+			t.Errorf("item %d: transaction mismatch: have %v, want %v", i, list.items[tx.Nonce()], tx)
+		}
+	}
+}
diff --git a/core/tx_pool.go b/core/tx_pool.go
index ec3d5c16b..c4dcceba0 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -20,7 +20,6 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
-	"sort"
 	"sync"
 	"time"
 
@@ -51,11 +50,6 @@ const (
 
 type stateFn func() (*state.StateDB, error)
 
-// TxList is a "list" of transactions belonging to an account, sorted by account
-// nonce. To allow gaps and avoid constant copying, the list is represented as a
-// hash map.
-type TxList map[uint64]*types.Transaction
-
 // TxPool contains all currently known transactions. Transactions
 // enter the pool when they are received from the network or submitted
 // locally. They exit the pool when they are included in the blockchain.
@@ -74,8 +68,8 @@ type TxPool struct {
 	localTx      *txSet
 	mu           sync.RWMutex
 
-	pending map[common.Address]TxList          // All currently processable transactions
-	queue   map[common.Address]TxList          // Queued but non-processable transactions
+	pending map[common.Address]*txList         // All currently processable transactions
+	queue   map[common.Address]*txList         // Queued but non-processable transactions
 	all     map[common.Hash]*types.Transaction // All transactions to allow lookups
 
 	wg sync.WaitGroup // for shutdown sync
@@ -86,8 +80,8 @@ type TxPool struct {
 func NewTxPool(config *ChainConfig, eventMux *event.TypeMux, currentStateFn stateFn, gasLimitFn func() *big.Int) *TxPool {
 	pool := &TxPool{
 		config:       config,
-		pending:      make(map[common.Address]TxList),
-		queue:        make(map[common.Address]TxList),
+		pending:      make(map[common.Address]*txList),
+		queue:        make(map[common.Address]*txList),
 		all:          make(map[common.Hash]*types.Transaction),
 		eventMux:     eventMux,
 		currentState: currentStateFn,
@@ -125,7 +119,7 @@ func (pool *TxPool) eventLoop() {
 			pool.minGasPrice = ev.Price
 			pool.mu.Unlock()
 		case RemovedTransactionEvent:
-			pool.AddTransactions(ev.Txs)
+			pool.AddBatch(ev.Txs)
 		}
 	}
 }
@@ -133,12 +127,12 @@ func (pool *TxPool) eventLoop() {
 func (pool *TxPool) resetState() {
 	currentState, err := pool.currentState()
 	if err != nil {
-		glog.V(logger.Info).Infoln("failed to get current state: %v", err)
+		glog.V(logger.Error).Infof("Failed to get current state: %v", err)
 		return
 	}
 	managedState := state.ManageState(currentState)
 	if err != nil {
-		glog.V(logger.Info).Infoln("failed to get managed state: %v", err)
+		glog.V(logger.Error).Infof("Failed to get managed state: %v", err)
 		return
 	}
 	pool.pendingState = managedState
@@ -147,22 +141,15 @@ func (pool *TxPool) resetState() {
 	// any transactions that have been included in the block or
 	// have been invalidated because of another transaction (e.g.
 	// higher gas price)
-	pool.validatePool()
-
-	// Loop over the pending transactions and base the nonce of the new
-	// pending transaction set.
-	for addr, txs := range pool.pending {
-		// Set the nonce. Transaction nonce can never be lower
-		// than the state nonce; validatePool took care of that.
-		for nonce, _ := range txs {
-			if pool.pendingState.GetNonce(addr) <= nonce {
-				pool.pendingState.SetNonce(addr, nonce+1)
-			}
-		}
+	pool.demoteUnexecutables()
+
+	// Update all accounts to the latest known pending nonce
+	for addr, list := range pool.pending {
+		pool.pendingState.SetNonce(addr, list.last+1)
 	}
 	// Check the queue and move transactions over to the pending if possible
 	// or remove those that have become invalid
-	pool.checkQueue()
+	pool.promoteExecutables()
 }
 
 func (pool *TxPool) Stop() {
@@ -178,46 +165,58 @@ func (pool *TxPool) State() *state.ManagedState {
 	return pool.pendingState
 }
 
+// Stats retrieves the current pool stats, namely the number of pending and the
+// number of queued (non-executable) transactions.
 func (pool *TxPool) Stats() (pending int, queued int) {
 	pool.mu.RLock()
 	defer pool.mu.RUnlock()
 
-	for _, txs := range pool.pending {
-		pending += len(txs)
+	for _, list := range pool.pending {
+		pending += list.Len()
 	}
-	for _, txs := range pool.queue {
-		queued += len(txs)
+	for _, list := range pool.queue {
+		queued += list.Len()
 	}
 	return
 }
 
 // Content retrieves the data content of the transaction pool, returning all the
-// pending as well as queued transactions, grouped by account and nonce.
-func (pool *TxPool) Content() (map[common.Address]TxList, map[common.Address]TxList) {
+// pending as well as queued transactions, grouped by account and sorted by nonce.
+func (pool *TxPool) Content() (map[common.Address]types.Transactions, map[common.Address]types.Transactions) {
 	pool.mu.RLock()
 	defer pool.mu.RUnlock()
 
-	// Retrieve all the pending transactions and sort by account and by nonce
-	pending := make(map[common.Address]TxList)
-	for addr, txs := range pool.pending {
-		copy := make(TxList)
-		for nonce, tx := range txs {
-			copy[nonce] = tx
-		}
-		pending[addr] = copy
-	}
-	// Retrieve all the queued transactions and sort by account and by nonce
-	queued := make(map[common.Address]TxList)
-	for addr, txs := range pool.queue {
-		copy := make(TxList)
-		for nonce, tx := range txs {
-			copy[nonce] = tx
-		}
-		queued[addr] = copy
+	pending := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.pending {
+		pending[addr] = list.Flatten()
+	}
+	queued := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.queue {
+		queued[addr] = list.Flatten()
 	}
 	return pending, queued
 }
 
+// Pending retrieves all currently processable transactions, groupped by origin
+// account and sorted by nonce. The returned transaction set is a copy and can be
+// freely modified by calling code.
+func (pool *TxPool) Pending() map[common.Address]types.Transactions {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
+
+	// check queue first
+	pool.promoteExecutables()
+
+	// invalidate any txs
+	pool.demoteUnexecutables()
+
+	pending := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.pending {
+		pending[addr] = list.Flatten()
+	}
+	return pending
+}
+
 // SetLocal marks a transaction as local, skipping gas price
 //  check against local miner minimum in the future
 func (pool *TxPool) SetLocal(tx *types.Transaction) {
@@ -283,340 +282,268 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 	return nil
 }
 
-// validate and queue transactions.
-func (self *TxPool) add(tx *types.Transaction) error {
+// add validates a transaction and inserts it into the non-executable queue for
+// later pending promotion and execution.
+func (pool *TxPool) add(tx *types.Transaction) error {
+	// If the transaction is alreayd known, discard it
 	hash := tx.Hash()
-
-	if self.all[hash] != nil {
-		return fmt.Errorf("Known transaction (%x)", hash[:4])
+	if pool.all[hash] != nil {
+		return fmt.Errorf("Known transaction: %x", hash[:4])
 	}
-	err := self.validateTx(tx)
-	if err != nil {
+	// Otherwise ensure basic validation passes nd queue it up
+	if err := pool.validateTx(tx); err != nil {
 		return err
 	}
-	self.queueTx(hash, tx)
+	pool.enqueueTx(hash, tx)
 
+	// Print a log message if low enough level is set
 	if glog.V(logger.Debug) {
-		var toname string
+		rcpt := "[NEW_CONTRACT]"
 		if to := tx.To(); to != nil {
-			toname = common.Bytes2Hex(to[:4])
-		} else {
-			toname = "[NEW_CONTRACT]"
+			rcpt = common.Bytes2Hex(to[:4])
 		}
-		// we can ignore the error here because From is
-		// verified in ValidateTransaction.
-		f, _ := tx.From()
-		from := common.Bytes2Hex(f[:4])
-		glog.Infof("(t) %x => %s (%v) %x\n", from, toname, tx.Value, hash)
+		from, _ := tx.From() // from already verified during tx validation
+		glog.Infof("(t) 0x%x => %s (%v) %x\n", from[:4], rcpt, tx.Value, hash)
 	}
-
 	return nil
 }
 
-// queueTx will queue an unknown transaction.
-func (self *TxPool) queueTx(hash common.Hash, tx *types.Transaction) {
-	addr, _ := tx.From() // already validated
-	if self.queue[addr] == nil {
-		self.queue[addr] = make(TxList)
+// enqueueTx inserts a new transction into the non-executable transaction queue.
+//
+// Note, this method assumes the pool lock is held!
+func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) {
+	// Try to insert the transaction into the future queue
+	from, _ := tx.From() // already validated
+	if pool.queue[from] == nil {
+		pool.queue[from] = newTxList(false)
 	}
-	// If the nonce is already used, discard the lower priced transaction
-	nonce := tx.Nonce()
-
-	if old, ok := self.queue[addr][nonce]; ok {
-		if old.GasPrice().Cmp(tx.GasPrice()) >= 0 {
-			return // Old was better, discard this
-		}
-		delete(self.all, old.Hash()) // New is better, drop and overwrite old one
+	inserted, old := pool.queue[from].Add(tx)
+	if !inserted {
+		return // An older transaction was better, discard this
+	}
+	// Discard any previous transaction and mark this
+	if old != nil {
+		delete(pool.all, old.Hash())
 	}
-	self.queue[addr][nonce] = tx
-	self.all[hash] = tx
+	pool.all[hash] = tx
 }
 
-// addTx will moves a transaction from the non-executable queue to the pending
-// (processable) list of transactions.
-func (pool *TxPool) addTx(addr common.Address, tx *types.Transaction) {
+// promoteTx adds a transaction to the pending (processable) list of transactions.
+//
+// Note, this method assumes the pool lock is held!
+func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.Transaction) {
 	// Init delayed since tx pool could have been started before any state sync
 	if pool.pendingState == nil {
 		pool.resetState()
 	}
-	// If the nonce is already used, discard the lower priced transaction
-	hash, nonce := tx.Hash(), tx.Nonce()
-
-	if old, ok := pool.pending[addr][nonce]; ok {
-		oldHash := old.Hash()
+	// Try to insert the transaction into the pending queue
+	if pool.pending[addr] == nil {
+		pool.pending[addr] = newTxList(true)
+	}
+	list := pool.pending[addr]
 
-		switch {
-		case oldHash == hash: // Nothing changed, noop
-			return
-		case old.GasPrice().Cmp(tx.GasPrice()) >= 0: // Old was better, discard this
-			delete(pool.all, hash)
-			return
-		default: // New is better, discard old
-			delete(pool.all, oldHash)
-		}
+	inserted, old := list.Add(tx)
+	if !inserted {
+		// An older transaction was better, discard this
+		delete(pool.all, hash)
+		return
 	}
-	// The transaction is being kept, insert it into the tx pool
-	if _, ok := pool.pending[addr]; !ok {
-		pool.pending[addr] = make(TxList)
+	// Otherwise discard any previous transaction and mark this
+	if old != nil {
+		delete(pool.all, old.Hash())
 	}
-	pool.pending[addr][nonce] = tx
-	pool.all[hash] = tx
-
-	// Increment the nonce on the pending state. This can only happen if
-	// the nonce is +1 to the previous one.
-	pool.pendingState.SetNonce(addr, nonce+1)
+	pool.all[hash] = tx // Failsafe to work around direct pending inserts (tests)
 
-	// Notify the subscribers. This event is posted in a goroutine
-	// because it's possible that somewhere during the post "Remove transaction"
-	// gets called which will then wait for the global tx pool lock and deadlock.
+	// Set the potentially new pending nonce and notify any subsystems of the new tx
+	pool.pendingState.SetNonce(addr, list.last+1)
 	go pool.eventMux.Post(TxPreEvent{tx})
 }
 
 // Add queues a single transaction in the pool if it is valid.
-func (self *TxPool) Add(tx *types.Transaction) error {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+func (pool *TxPool) Add(tx *types.Transaction) error {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
-	if err := self.add(tx); err != nil {
+	if err := pool.add(tx); err != nil {
 		return err
 	}
-	self.checkQueue()
+	pool.promoteExecutables()
+
 	return nil
 }
 
-// AddTransactions attempts to queue all valid transactions in txs.
-func (self *TxPool) AddTransactions(txs []*types.Transaction) {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+// AddBatch attempts to queue a batch of transactions.
+func (pool *TxPool) AddBatch(txs []*types.Transaction) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
 	for _, tx := range txs {
-		if err := self.add(tx); err != nil {
+		if err := pool.add(tx); err != nil {
 			glog.V(logger.Debug).Infoln("tx error:", err)
-		} else {
-			h := tx.Hash()
-			glog.V(logger.Debug).Infof("tx %x\n", h[:4])
 		}
 	}
-
-	// check and validate the queue
-	self.checkQueue()
+	pool.promoteExecutables()
 }
 
-// GetTransaction returns a transaction if it is contained in the pool
+// Get returns a transaction if it is contained in the pool
 // and nil otherwise.
-func (tp *TxPool) GetTransaction(hash common.Hash) *types.Transaction {
-	tp.mu.RLock()
-	defer tp.mu.RUnlock()
-
-	return tp.all[hash]
-}
-
-// GetTransactions returns all currently processable transactions.
-// The returned slice may be modified by the caller.
-func (self *TxPool) GetTransactions() types.Transactions {
-	self.mu.Lock()
-	defer self.mu.Unlock()
-
-	// check queue first
-	self.checkQueue()
-
-	// invalidate any txs
-	self.validatePool()
+func (pool *TxPool) Get(hash common.Hash) *types.Transaction {
+	pool.mu.RLock()
+	defer pool.mu.RUnlock()
 
-	count := 0
-	for _, txs := range self.pending {
-		count += len(txs)
-	}
-	pending := make(types.Transactions, 0, count)
-	for _, txs := range self.pending {
-		for _, tx := range txs {
-			pending = append(pending, tx)
-		}
-	}
-	return pending
+	return pool.all[hash]
 }
 
-// RemoveTransactions removes all given transactions from the pool.
-func (self *TxPool) RemoveTransactions(txs types.Transactions) {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+// Remove removes the transaction with the given hash from the pool.
+func (pool *TxPool) Remove(hash common.Hash) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
-	for _, tx := range txs {
-		self.removeTx(tx.Hash())
-	}
+	pool.removeTx(hash)
 }
 
-// RemoveTx removes the transaction with the given hash from the pool.
-func (pool *TxPool) RemoveTx(hash common.Hash) {
+// RemoveBatch removes all given transactions from the pool.
+func (pool *TxPool) RemoveBatch(txs types.Transactions) {
 	pool.mu.Lock()
 	defer pool.mu.Unlock()
 
-	pool.removeTx(hash)
+	for _, tx := range txs {
+		pool.removeTx(tx.Hash())
+	}
 }
 
+// removeTx iterates removes a single transaction from the queue, moving all
+// subsequent transactions back to the future queue.
 func (pool *TxPool) removeTx(hash common.Hash) {
 	// Fetch the transaction we wish to delete
 	tx, ok := pool.all[hash]
 	if !ok {
 		return
 	}
-	addr, _ := tx.From()
+	addr, _ := tx.From() // already validated during insertion
 
-	// Remove it from all internal lists
+	// Remove it from the list of known transactions
 	delete(pool.all, hash)
 
-	delete(pool.pending[addr], tx.Nonce())
-	if len(pool.pending[addr]) == 0 {
-		delete(pool.pending, addr)
+	// Remove the transaction from the pending lists and reset the account nonce
+	if pending := pool.pending[addr]; pending != nil {
+		if removed, invalids := pending.Remove(tx); removed {
+			// If no more transactions are left, remove the list and reset the nonce
+			if pending.Empty() {
+				delete(pool.pending, addr)
+				pool.pendingState.SetNonce(addr, tx.Nonce())
+			} else {
+				// Otherwise update the nonce and postpone any invalidated transactions
+				pool.pendingState.SetNonce(addr, pending.last)
+				for _, tx := range invalids {
+					pool.enqueueTx(tx.Hash(), tx)
+				}
+			}
+		}
 	}
-	delete(pool.queue[addr], tx.Nonce())
-	if len(pool.queue[addr]) == 0 {
-		delete(pool.queue, addr)
+	// Transaction is in the future queue
+	if future := pool.queue[addr]; future != nil {
+		future.Remove(tx)
+		if future.Empty() {
+			delete(pool.queue, addr)
+		}
 	}
 }
 
-// checkQueue moves transactions that have become processable from the pool's
-// queue to the set of pending transactions.
-func (pool *TxPool) checkQueue() {
+// promoteExecutables moves transactions that have become processable from the
+// future queue to the set of pending transactions. During this process, all
+// invalidated transactions (low nonce, low balance) are deleted.
+func (pool *TxPool) promoteExecutables() {
 	// Init delayed since tx pool could have been started before any state sync
 	if pool.pendingState == nil {
 		pool.resetState()
 	}
-
-	var promote txQueue
-	for address, txs := range pool.queue {
-		currentState, err := pool.currentState()
-		if err != nil {
-			glog.Errorf("could not get current state: %v", err)
-			return
+	// Retrieve the current state to allow nonce and balance checking
+	state, err := pool.currentState()
+	if err != nil {
+		glog.Errorf("Could not get current state: %v", err)
+		return
+	}
+	// Iterate over all accounts and promote any executable transactions
+	for addr, list := range pool.queue {
+		// Drop all transactions that are deemed too old (low nonce)
+		for _, tx := range list.Forward(state.GetNonce(addr)) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed old queued transaction: %v", tx)
+			}
+			delete(pool.all, tx.Hash())
 		}
-		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 nonce, tx := range txs {
-			// Drop processed or out of fund transactions
-			if 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, nonce)
-				delete(pool.all, tx.Hash())
-
-				continue
+		// Drop all transactions that are too costly (low balance)
+		drops, _ := list.Filter(state.GetBalance(addr))
+		for _, tx := range drops {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed unpayable queued transaction: %v", tx)
 			}
-			// Collect the remaining transactions for the next pass.
-			promote = append(promote, txQueueEntry{address, tx})
+			delete(pool.all, tx.Hash())
 		}
-		// 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(entry.Hash().Bytes()))
-					}
-					for _, drop := range promote[i+maxQueued:] {
-						delete(txs, drop.Nonce())
-						delete(pool.all, drop.Hash())
-					}
-				}
-				break
+		// Gather all executable transactions and promote them
+		for _, tx := range list.Ready(pool.pendingState.GetNonce(addr)) {
+			if glog.V(logger.Core) {
+				glog.Infof("Promoting queued transaction: %v", tx)
 			}
-			// Otherwise promote the transaction and move the guess nonce if needed
-			pool.addTx(address, entry.Transaction)
-			delete(txs, entry.Nonce())
-
-			if entry.Nonce() == guessedNonce {
-				guessedNonce++
+			pool.promoteTx(addr, tx.Hash(), tx)
+		}
+		// Drop all transactions over the allowed limit
+		for _, tx := range list.Cap(maxQueued) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed cap-exceeding queued transaction: %v", tx)
 			}
+			delete(pool.all, tx.Hash())
 		}
 		// Delete the entire queue entry if it became empty.
-		if len(txs) == 0 {
-			delete(pool.queue, address)
+		if list.Empty() {
+			delete(pool.queue, addr)
 		}
 	}
 }
 
-// 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() {
+// demoteUnexecutables removes invalid and processed transactions from the pools
+// executable/pending queue and any subsequent transactions that become unexecutable
+// are moved back into the future queue.
+func (pool *TxPool) demoteUnexecutables() {
+	// Retrieve the current state to allow nonce and balance checking
 	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)
+	// Iterate over all accounts and demote any non-executable transactions
+	for addr, list := range pool.pending {
+		nonce := state.GetNonce(addr)
 
-	for addr, txs := range pool.pending {
-		for nonce, tx := range txs {
-			// Perform light nonce and balance validation
-			balance := balanceCache[addr]
-			if balance == nil {
-				balance = state.GetBalance(addr)
-				balanceCache[addr] = balance
+		// Drop all transactions that are deemed too old (low nonce)
+		for _, tx := range list.Forward(nonce) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed old pending transaction: %v", tx)
 			}
-			if past := state.GetNonce(addr) > nonce; past || balance.Cmp(tx.Cost()) < 0 {
-				// Remove an already past it invalidated transaction
-				if glog.V(logger.Core) {
-					glog.Infof("removed tx (%v) from pool: low tx nonce or out of funds\n", tx)
-				}
-				delete(pool.pending[addr], nonce)
-				if len(pool.pending[addr]) == 0 {
-					delete(pool.pending, addr)
-				}
-				delete(pool.all, tx.Hash())
-
-				// Track the smallest invalid nonce to postpone subsequent transactions
-				if !past {
-					if prev, ok := gaps[addr]; !ok || nonce < prev {
-						gaps[addr] = nonce
-					}
-				}
+			delete(pool.all, tx.Hash())
+		}
+		// Drop all transactions that are too costly (low balance), and queue any invalids back for later
+		drops, invalids := list.Filter(state.GetBalance(addr))
+		for _, tx := range drops {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed unpayable pending transaction: %v", tx)
 			}
+			delete(pool.all, tx.Hash())
 		}
-	}
-	// Move all transactions after a gap back to the future queue
-	if len(gaps) > 0 {
-		for addr, txs := range pool.pending {
-			for nonce, tx := range txs {
-				if gap, ok := gaps[addr]; ok && nonce >= gap {
-					if glog.V(logger.Core) {
-						glog.Infof("postponed tx (%v) due to introduced gap\n", tx)
-					}
-					delete(pool.pending[addr], nonce)
-					if len(pool.pending[addr]) == 0 {
-						delete(pool.pending, addr)
-					}
-					pool.queueTx(tx.Hash(), tx)
-				}
+		for _, tx := range invalids {
+			if glog.V(logger.Core) {
+				glog.Infof("Demoting pending transaction: %v", tx)
 			}
+			pool.enqueueTx(tx.Hash(), tx)
+		}
+		// Delete the entire queue entry if it became empty.
+		if list.Empty() {
+			delete(pool.pending, addr)
 		}
 	}
 }
 
-type txQueue []txQueueEntry
-
-type txQueueEntry struct {
-	addr common.Address
-	*types.Transaction
-}
-
-func (q txQueue) Len() int           { return len(q) }
-func (q txQueue) Swap(i, j int)      { q[i], q[j] = q[j], q[i] }
-func (q txQueue) Less(i, j int) bool { return q[i].Nonce() < q[j].Nonce() }
-
 // txSet represents a set of transaction hashes in which entries
 //  are automatically dropped after txSetDuration time
 type txSet struct {
diff --git a/core/tx_pool_test.go b/core/tx_pool_test.go
index 8aa69233d..ec54d8c0e 100644
--- a/core/tx_pool_test.go
+++ b/core/tx_pool_test.go
@@ -91,9 +91,9 @@ func TestTransactionQueue(t *testing.T) {
 	from, _ := tx.From()
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1000))
-	pool.queueTx(tx.Hash(), tx)
+	pool.enqueueTx(tx.Hash(), tx)
 
-	pool.checkQueue()
+	pool.promoteExecutables()
 	if len(pool.pending) != 1 {
 		t.Error("expected valid txs to be 1 is", len(pool.pending))
 	}
@@ -101,14 +101,14 @@ func TestTransactionQueue(t *testing.T) {
 	tx = transaction(1, big.NewInt(100), key)
 	from, _ = tx.From()
 	currentState.SetNonce(from, 2)
-	pool.queueTx(tx.Hash(), tx)
-	pool.checkQueue()
-	if _, ok := pool.pending[from][tx.Nonce()]; ok {
+	pool.enqueueTx(tx.Hash(), tx)
+	pool.promoteExecutables()
+	if _, ok := pool.pending[from].items[tx.Nonce()]; ok {
 		t.Error("expected transaction to be in tx pool")
 	}
 
-	if len(pool.queue[from]) > 0 {
-		t.Error("expected transaction queue to be empty. is", len(pool.queue[from]))
+	if len(pool.queue) > 0 {
+		t.Error("expected transaction queue to be empty. is", len(pool.queue))
 	}
 
 	pool, key = setupTxPool()
@@ -118,17 +118,17 @@ func TestTransactionQueue(t *testing.T) {
 	from, _ = tx1.From()
 	currentState, _ = pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1000))
-	pool.queueTx(tx1.Hash(), tx1)
-	pool.queueTx(tx2.Hash(), tx2)
-	pool.queueTx(tx3.Hash(), tx3)
+	pool.enqueueTx(tx1.Hash(), tx1)
+	pool.enqueueTx(tx2.Hash(), tx2)
+	pool.enqueueTx(tx3.Hash(), tx3)
 
-	pool.checkQueue()
+	pool.promoteExecutables()
 
 	if len(pool.pending) != 1 {
 		t.Error("expected tx pool to be 1, got", len(pool.pending))
 	}
-	if len(pool.queue[from]) != 2 {
-		t.Error("expected len(queue) == 2, got", len(pool.queue[from]))
+	if pool.queue[from].Len() != 2 {
+		t.Error("expected len(queue) == 2, got", pool.queue[from].Len())
 	}
 }
 
@@ -138,24 +138,21 @@ func TestRemoveTx(t *testing.T) {
 	from, _ := tx.From()
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1))
-	pool.queueTx(tx.Hash(), tx)
-	pool.addTx(from, tx)
+
+	pool.enqueueTx(tx.Hash(), tx)
+	pool.promoteTx(from, tx.Hash(), tx)
 	if len(pool.queue) != 1 {
 		t.Error("expected queue to be 1, got", len(pool.queue))
 	}
-
 	if len(pool.pending) != 1 {
-		t.Error("expected txs to be 1, got", len(pool.pending))
+		t.Error("expected pending to be 1, got", len(pool.pending))
 	}
-
-	pool.RemoveTx(tx.Hash())
-
+	pool.Remove(tx.Hash())
 	if len(pool.queue) > 0 {
 		t.Error("expected queue to be 0, got", len(pool.queue))
 	}
-
 	if len(pool.pending) > 0 {
-		t.Error("expected txs to be 0, got", len(pool.pending))
+		t.Error("expected pending to be 0, got", len(pool.pending))
 	}
 }
 
@@ -188,7 +185,7 @@ func TestTransactionChainFork(t *testing.T) {
 	if err := pool.add(tx); err != nil {
 		t.Error("didn't expect error", err)
 	}
-	pool.RemoveTransactions([]*types.Transaction{tx})
+	pool.RemoveBatch([]*types.Transaction{tx})
 
 	// reset the pool's internal state
 	resetState()
@@ -221,22 +218,22 @@ func TestTransactionDoubleNonce(t *testing.T) {
 	if err := pool.add(tx2); err != nil {
 		t.Error("didn't expect error", err)
 	}
-	pool.checkQueue()
-	if len(pool.pending[addr]) != 1 {
-		t.Error("expected 1 pending transactions, got", len(pool.pending))
+	pool.promoteExecutables()
+	if pool.pending[addr].Len() != 1 {
+		t.Error("expected 1 pending transactions, got", pool.pending[addr].Len())
 	}
-	if tx := pool.pending[addr][0]; tx.Hash() != tx2.Hash() {
+	if tx := pool.pending[addr].items[0]; tx.Hash() != tx2.Hash() {
 		t.Errorf("transaction mismatch: have %x, want %x", tx.Hash(), tx2.Hash())
 	}
 	// Add the thid transaction and ensure it's not saved (smaller price)
 	if err := pool.add(tx3); err != nil {
 		t.Error("didn't expect error", err)
 	}
-	pool.checkQueue()
-	if len(pool.pending[addr]) != 1 {
-		t.Error("expected 1 pending transactions, got", len(pool.pending))
+	pool.promoteExecutables()
+	if pool.pending[addr].Len() != 1 {
+		t.Error("expected 1 pending transactions, got", pool.pending[addr].Len())
 	}
-	if tx := pool.pending[addr][0]; tx.Hash() != tx2.Hash() {
+	if tx := pool.pending[addr].items[0]; tx.Hash() != tx2.Hash() {
 		t.Errorf("transaction mismatch: have %x, want %x", tx.Hash(), tx2.Hash())
 	}
 	// Ensure the total transaction count is correct
@@ -254,11 +251,11 @@ func TestMissingNonce(t *testing.T) {
 	if err := pool.add(tx); err != nil {
 		t.Error("didn't expect error", err)
 	}
-	if len(pool.pending[addr]) != 0 {
-		t.Error("expected 0 pending transactions, got", len(pool.pending[addr]))
+	if len(pool.pending) != 0 {
+		t.Error("expected 0 pending transactions, got", len(pool.pending))
 	}
-	if len(pool.queue[addr]) != 1 {
-		t.Error("expected 1 queued transaction, got", len(pool.queue[addr]))
+	if pool.queue[addr].Len() != 1 {
+		t.Error("expected 1 queued transaction, got", pool.queue[addr].Len())
 	}
 	if len(pool.all) != 1 {
 		t.Error("expected 1 total transactions, got", len(pool.all))
@@ -293,8 +290,8 @@ func TestRemovedTxEvent(t *testing.T) {
 	currentState.AddBalance(from, big.NewInt(1000000000000))
 	pool.eventMux.Post(RemovedTransactionEvent{types.Transactions{tx}})
 	pool.eventMux.Post(ChainHeadEvent{nil})
-	if len(pool.pending[from]) != 1 {
-		t.Error("expected 1 pending tx, got", len(pool.pending[from]))
+	if pool.pending[from].Len() != 1 {
+		t.Error("expected 1 pending tx, got", pool.pending[from].Len())
 	}
 	if len(pool.all) != 1 {
 		t.Error("expected 1 total transactions, got", len(pool.all))
@@ -318,27 +315,27 @@ func TestTransactionDropping(t *testing.T) {
 		tx10 = transaction(10, big.NewInt(100), key)
 		tx11 = transaction(11, big.NewInt(200), key)
 	)
-	pool.addTx(account, tx0)
-	pool.addTx(account, tx1)
-	pool.queueTx(tx10.Hash(), tx10)
-	pool.queueTx(tx11.Hash(), tx11)
+	pool.promoteTx(account, tx0.Hash(), tx0)
+	pool.promoteTx(account, tx1.Hash(), tx1)
+	pool.enqueueTx(tx10.Hash(), tx10)
+	pool.enqueueTx(tx11.Hash(), tx11)
 
 	// Check that pre and post validations leave the pool as is
-	if len(pool.pending[account]) != 2 {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending[account]), 2)
+	if pool.pending[account].Len() != 2 {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), 2)
 	}
-	if len(pool.queue[account]) != 2 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue[account]), 2)
+	if pool.queue[account].Len() != 2 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 2)
 	}
 	if len(pool.all) != 4 {
 		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), 4)
 	}
 	pool.resetState()
-	if len(pool.pending[account]) != 2 {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending[account]), 2)
+	if pool.pending[account].Len() != 2 {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), 2)
 	}
-	if len(pool.queue[account]) != 2 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue[account]), 2)
+	if pool.queue[account].Len() != 2 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 2)
 	}
 	if len(pool.all) != 4 {
 		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), 4)
@@ -347,16 +344,16 @@ func TestTransactionDropping(t *testing.T) {
 	state.AddBalance(account, big.NewInt(-750))
 	pool.resetState()
 
-	if _, ok := pool.pending[account][tx0.Nonce()]; !ok {
+	if _, ok := pool.pending[account].items[tx0.Nonce()]; !ok {
 		t.Errorf("funded pending transaction missing: %v", tx0)
 	}
-	if _, ok := pool.pending[account][tx1.Nonce()]; ok {
+	if _, ok := pool.pending[account].items[tx1.Nonce()]; ok {
 		t.Errorf("out-of-fund pending transaction present: %v", tx1)
 	}
-	if _, ok := pool.queue[account][tx10.Nonce()]; !ok {
+	if _, ok := pool.queue[account].items[tx10.Nonce()]; !ok {
 		t.Errorf("funded queued transaction missing: %v", tx10)
 	}
-	if _, ok := pool.queue[account][tx11.Nonce()]; ok {
+	if _, ok := pool.queue[account].items[tx11.Nonce()]; ok {
 		t.Errorf("out-of-fund queued transaction present: %v", tx11)
 	}
 	if len(pool.all) != 2 {
@@ -384,25 +381,25 @@ func TestTransactionPostponing(t *testing.T) {
 		} else {
 			tx = transaction(uint64(i), big.NewInt(500), key)
 		}
-		pool.addTx(account, tx)
+		pool.promoteTx(account, tx.Hash(), tx)
 		txns = append(txns, tx)
 	}
 	// Check that pre and post validations leave the pool as is
-	if len(pool.pending[account]) != len(txns) {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending[account]), len(txns))
+	if pool.pending[account].Len() != len(txns) {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), len(txns))
 	}
-	if len(pool.queue[account]) != 0 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue[account]), 0)
+	if len(pool.queue) != 0 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 0)
 	}
 	if len(pool.all) != len(txns) {
 		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), len(txns))
 	}
 	pool.resetState()
-	if len(pool.pending[account]) != len(txns) {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending[account]), len(txns))
+	if pool.pending[account].Len() != len(txns) {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), len(txns))
 	}
-	if len(pool.queue[account]) != 0 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue[account]), 0)
+	if len(pool.queue) != 0 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 0)
 	}
 	if len(pool.all) != len(txns) {
 		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), len(txns))
@@ -411,25 +408,25 @@ func TestTransactionPostponing(t *testing.T) {
 	state.AddBalance(account, big.NewInt(-750))
 	pool.resetState()
 
-	if _, ok := pool.pending[account][txns[0].Nonce()]; !ok {
+	if _, ok := pool.pending[account].items[txns[0].Nonce()]; !ok {
 		t.Errorf("tx %d: valid and funded transaction missing from pending pool: %v", 0, txns[0])
 	}
-	if _, ok := pool.queue[account][txns[0].Nonce()]; ok {
+	if _, ok := pool.queue[account].items[txns[0].Nonce()]; ok {
 		t.Errorf("tx %d: valid and funded transaction present in future queue: %v", 0, txns[0])
 	}
 	for i, tx := range txns[1:] {
 		if i%2 == 1 {
-			if _, ok := pool.pending[account][tx.Nonce()]; ok {
+			if _, ok := pool.pending[account].items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: valid but future transaction present in pending pool: %v", i+1, tx)
 			}
-			if _, ok := pool.queue[account][tx.Nonce()]; !ok {
+			if _, ok := pool.queue[account].items[tx.Nonce()]; !ok {
 				t.Errorf("tx %d: valid but future transaction missing from future queue: %v", i+1, tx)
 			}
 		} else {
-			if _, ok := pool.pending[account][tx.Nonce()]; ok {
+			if _, ok := pool.pending[account].items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: out-of-fund transaction present in pending pool: %v", i+1, tx)
 			}
-			if _, ok := pool.queue[account][tx.Nonce()]; ok {
+			if _, ok := pool.queue[account].items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: out-of-fund transaction present in future queue: %v", i+1, tx)
 			}
 		}
@@ -458,12 +455,12 @@ func TestTransactionQueueLimiting(t *testing.T) {
 			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, len(pool.pending), 0)
 		}
 		if i <= maxQueued {
-			if len(pool.queue[account]) != int(i) {
-				t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, len(pool.queue[account]), i)
+			if pool.queue[account].Len() != int(i) {
+				t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, pool.queue[account].Len(), i)
 			}
 		} else {
-			if len(pool.queue[account]) != maxQueued {
-				t.Errorf("tx %d: queue limit mismatch: have %d, want %d", i, len(pool.queue[account]), maxQueued)
+			if pool.queue[account].Len() != maxQueued {
+				t.Errorf("tx %d: queue limit mismatch: have %d, want %d", i, pool.queue[account].Len(), maxQueued)
 			}
 		}
 	}
@@ -488,11 +485,11 @@ func TestTransactionPendingLimiting(t *testing.T) {
 		if err := pool.Add(transaction(i, big.NewInt(100000), key)); err != nil {
 			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
 		}
-		if len(pool.pending[account]) != int(i)+1 {
-			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, len(pool.pending[account]), i+1)
+		if pool.pending[account].Len() != int(i)+1 {
+			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, pool.pending[account].Len(), i+1)
 		}
-		if len(pool.queue[account]) != 0 {
-			t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, len(pool.queue[account]), 0)
+		if len(pool.queue) != 0 {
+			t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, pool.queue[account].Len(), 0)
 		}
 	}
 	if len(pool.all) != maxQueued+5 {
@@ -517,7 +514,7 @@ func testTransactionLimitingEquivalency(t *testing.T, origin uint64) {
 			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
 		}
 	}
-	// Add a batch of transactions to a pool in one bit batch
+	// Add a batch of transactions to a pool in one big batch
 	pool2, key2 := setupTxPool()
 	account2, _ := transaction(0, big.NewInt(0), key2).From()
 	state2, _ := pool2.currentState()
@@ -527,14 +524,14 @@ func testTransactionLimitingEquivalency(t *testing.T, origin uint64) {
 	for i := uint64(0); i < maxQueued+5; i++ {
 		txns = append(txns, transaction(origin+i, big.NewInt(100000), key2))
 	}
-	pool2.AddTransactions(txns)
+	pool2.AddBatch(txns)
 
 	// Ensure the batch optimization honors the same pool mechanics
 	if len(pool1.pending) != len(pool2.pending) {
 		t.Errorf("pending transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.pending), len(pool2.pending))
 	}
-	if len(pool1.queue[account1]) != len(pool2.queue[account2]) {
-		t.Errorf("queued transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.queue[account1]), len(pool2.queue[account2]))
+	if len(pool1.queue) != len(pool2.queue) {
+		t.Errorf("queued transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.queue), len(pool2.queue))
 	}
 	if len(pool1.all) != len(pool2.all) {
 		t.Errorf("total transaction count mismatch: one-by-one algo %d, batch algo %d", len(pool1.all), len(pool2.all))
@@ -543,11 +540,11 @@ func testTransactionLimitingEquivalency(t *testing.T, origin uint64) {
 
 // Benchmarks the speed of validating the contents of the pending queue of the
 // transaction pool.
-func BenchmarkValidatePool100(b *testing.B)   { benchmarkValidatePool(b, 100) }
-func BenchmarkValidatePool1000(b *testing.B)  { benchmarkValidatePool(b, 1000) }
-func BenchmarkValidatePool10000(b *testing.B) { benchmarkValidatePool(b, 10000) }
+func BenchmarkPendingDemotion100(b *testing.B)   { benchmarkPendingDemotion(b, 100) }
+func BenchmarkPendingDemotion1000(b *testing.B)  { benchmarkPendingDemotion(b, 1000) }
+func BenchmarkPendingDemotion10000(b *testing.B) { benchmarkPendingDemotion(b, 10000) }
 
-func benchmarkValidatePool(b *testing.B, size int) {
+func benchmarkPendingDemotion(b *testing.B, size int) {
 	// Add a batch of transactions to a pool one by one
 	pool, key := setupTxPool()
 	account, _ := transaction(0, big.NewInt(0), key).From()
@@ -556,22 +553,22 @@ func benchmarkValidatePool(b *testing.B, size int) {
 
 	for i := 0; i < size; i++ {
 		tx := transaction(uint64(i), big.NewInt(100000), key)
-		pool.addTx(account, tx)
+		pool.promoteTx(account, tx.Hash(), tx)
 	}
 	// Benchmark the speed of pool validation
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		pool.validatePool()
+		pool.demoteUnexecutables()
 	}
 }
 
 // Benchmarks the speed of scheduling the contents of the future queue of the
 // transaction pool.
-func BenchmarkCheckQueue100(b *testing.B)   { benchmarkCheckQueue(b, 100) }
-func BenchmarkCheckQueue1000(b *testing.B)  { benchmarkCheckQueue(b, 1000) }
-func BenchmarkCheckQueue10000(b *testing.B) { benchmarkCheckQueue(b, 10000) }
+func BenchmarkFuturePromotion100(b *testing.B)   { benchmarkFuturePromotion(b, 100) }
+func BenchmarkFuturePromotion1000(b *testing.B)  { benchmarkFuturePromotion(b, 1000) }
+func BenchmarkFuturePromotion10000(b *testing.B) { benchmarkFuturePromotion(b, 10000) }
 
-func benchmarkCheckQueue(b *testing.B, size int) {
+func benchmarkFuturePromotion(b *testing.B, size int) {
 	// Add a batch of transactions to a pool one by one
 	pool, key := setupTxPool()
 	account, _ := transaction(0, big.NewInt(0), key).From()
@@ -580,11 +577,56 @@ func benchmarkCheckQueue(b *testing.B, size int) {
 
 	for i := 0; i < size; i++ {
 		tx := transaction(uint64(1+i), big.NewInt(100000), key)
-		pool.queueTx(tx.Hash(), tx)
+		pool.enqueueTx(tx.Hash(), tx)
 	}
 	// Benchmark the speed of pool validation
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		pool.checkQueue()
+		pool.promoteExecutables()
+	}
+}
+
+// Benchmarks the speed of iterative transaction insertion.
+func BenchmarkPoolInsert(b *testing.B) {
+	// Generate a batch of transactions to enqueue into the pool
+	pool, key := setupTxPool()
+	account, _ := transaction(0, big.NewInt(0), key).From()
+	state, _ := pool.currentState()
+	state.AddBalance(account, big.NewInt(1000000))
+
+	txs := make(types.Transactions, b.N)
+	for i := 0; i < b.N; i++ {
+		txs[i] = transaction(uint64(i), big.NewInt(100000), key)
+	}
+	// Benchmark importing the transactions into the queue
+	b.ResetTimer()
+	for _, tx := range txs {
+		pool.Add(tx)
+	}
+}
+
+// Benchmarks the speed of batched transaction insertion.
+func BenchmarkPoolBatchInsert100(b *testing.B)   { benchmarkPoolBatchInsert(b, 100) }
+func BenchmarkPoolBatchInsert1000(b *testing.B)  { benchmarkPoolBatchInsert(b, 1000) }
+func BenchmarkPoolBatchInsert10000(b *testing.B) { benchmarkPoolBatchInsert(b, 10000) }
+
+func benchmarkPoolBatchInsert(b *testing.B, size int) {
+	// Generate a batch of transactions to enqueue into the pool
+	pool, key := setupTxPool()
+	account, _ := transaction(0, big.NewInt(0), key).From()
+	state, _ := pool.currentState()
+	state.AddBalance(account, big.NewInt(1000000))
+
+	batches := make([]types.Transactions, b.N)
+	for i := 0; i < b.N; i++ {
+		batches[i] = make(types.Transactions, size)
+		for j := 0; j < size; j++ {
+			batches[i][j] = transaction(uint64(size*i+j), big.NewInt(100000), key)
+		}
+	}
+	// Benchmark importing the transactions into the queue
+	b.ResetTimer()
+	for _, batch := range batches {
+		pool.AddBatch(batch)
 	}
 }
diff --git a/core/types/transaction.go b/core/types/transaction.go
index d369d7772..af48e4d07 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"io"
 	"math/big"
-	"sort"
 	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -439,37 +438,29 @@ func (s *TxByPrice) Pop() interface{} {
 // sender accounts and sorts them by nonce. After the account nonce ordering is
 // satisfied, the results are merged back together by price, always comparing only
 // the head transaction from each account. This is done via a heap to keep it fast.
-func SortByPriceAndNonce(txs []*Transaction) {
-	// Separate the transactions by account and sort by nonce
-	byNonce := make(map[common.Address][]*Transaction)
-	for _, tx := range txs {
-		acc, _ := tx.From() // we only sort valid txs so this cannot fail
-		byNonce[acc] = append(byNonce[acc], tx)
-	}
-	for _, accTxs := range byNonce {
-		sort.Sort(TxByNonce(accTxs))
-	}
+func SortByPriceAndNonce(txs map[common.Address]Transactions) Transactions {
 	// Initialize a price based heap with the head transactions
-	byPrice := make(TxByPrice, 0, len(byNonce))
-	for acc, accTxs := range byNonce {
+	byPrice := make(TxByPrice, 0, len(txs))
+	for acc, accTxs := range txs {
 		byPrice = append(byPrice, accTxs[0])
-		byNonce[acc] = accTxs[1:]
+		txs[acc] = accTxs[1:]
 	}
 	heap.Init(&byPrice)
 
 	// Merge by replacing the best with the next from the same account
-	txs = txs[:0]
+	var sorted Transactions
 	for len(byPrice) > 0 {
 		// Retrieve the next best transaction by price
 		best := heap.Pop(&byPrice).(*Transaction)
 
 		// Push in its place the next transaction from the same account
 		acc, _ := best.From() // we only sort valid txs so this cannot fail
-		if accTxs, ok := byNonce[acc]; ok && len(accTxs) > 0 {
+		if accTxs, ok := txs[acc]; ok && len(accTxs) > 0 {
 			heap.Push(&byPrice, accTxs[0])
-			byNonce[acc] = accTxs[1:]
+			txs[acc] = accTxs[1:]
 		}
 		// Accumulate the best priced transaction
-		txs = append(txs, best)
+		sorted = append(sorted, best)
 	}
+	return sorted
 }
diff --git a/core/types/transaction_test.go b/core/types/transaction_test.go
index 62420e71f..c6e6e3790 100644
--- a/core/types/transaction_test.go
+++ b/core/types/transaction_test.go
@@ -128,15 +128,16 @@ func TestTransactionPriceNonceSort(t *testing.T) {
 		keys[i], _ = crypto.GenerateKey()
 	}
 	// Generate a batch of transactions with overlapping values, but shifted nonces
-	txs := []*Transaction{}
+	groups := map[common.Address]Transactions{}
 	for start, key := range keys {
+		addr := crypto.PubkeyToAddress(key.PublicKey)
 		for i := 0; i < 25; i++ {
 			tx, _ := NewTransaction(uint64(start+i), common.Address{}, big.NewInt(100), big.NewInt(100), big.NewInt(int64(start+i)), nil).SignECDSA(key)
-			txs = append(txs, tx)
+			groups[addr] = append(groups[addr], tx)
 		}
 	}
 	// Sort the transactions and cross check the nonce ordering
-	SortByPriceAndNonce(txs)
+	txs := SortByPriceAndNonce(groups)
 	for i, txi := range txs {
 		fromi, _ := txi.From()