Merge pull request #34 from ava-labs/devv0.3.0-rc.5

Dev

1 files changed, 168 insertions, 87 deletions

diff --git a/core/tx_pool.go b/core/tx_pool.go
index 5b2a3c0..848627a 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -18,7 +18,6 @@ package core
 
 import (
 	"errors"
-	"fmt"
 	"math"
 	"math/big"
 	"sort"
@@ -28,26 +27,38 @@ import (
 	"github.com/ava-labs/coreth/core/state"
 	"github.com/ava-labs/coreth/core/types"
 	"github.com/ava-labs/coreth/params"
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/common/prque"
-	"github.com/ava-labs/go-ethereum/event"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/prque"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
 )
 
 const (
 	// chainHeadChanSize is the size of channel listening to ChainHeadEvent.
 	chainHeadChanSize = 10
+
+	// txSlotSize is used to calculate how many data slots a single transaction
+	// takes up based on its size. The slots are used as DoS protection, ensuring
+	// that validating a new transaction remains a constant operation (in reality
+	// O(maxslots), where max slots are 4 currently).
+	txSlotSize = 32 * 1024
+
+	// txMaxSize is the maximum size a single transaction can have. This field has
+	// non-trivial consequences: larger transactions are significantly harder and
+	// more expensive to propagate; larger transactions also take more resources
+	// to validate whether they fit into the pool or not.
+	txMaxSize = 4 * txSlotSize // 128KB
 )
 
 var (
+	// ErrAlreadyKnown is returned if the transactions is already contained
+	// within the pool.
+	ErrAlreadyKnown = errors.New("already known")
+
 	// ErrInvalidSender is returned if the transaction contains an invalid signature.
 	ErrInvalidSender = errors.New("invalid sender")
 
-	// ErrNonceTooLow is returned if the nonce of a transaction is lower than the
-	// one present in the local chain.
-	ErrNonceTooLow = errors.New("nonce too low")
-
 	// ErrUnderpriced is returned if a transaction's gas price is below the minimum
 	// configured for the transaction pool.
 	ErrUnderpriced = errors.New("transaction underpriced")
@@ -56,19 +67,11 @@ var (
 	// with a different one without the required price bump.
 	ErrReplaceUnderpriced = errors.New("replacement transaction underpriced")
 
-	// ErrInsufficientFunds is returned if the total cost of executing a transaction
-	// is higher than the balance of the user's account.
-	ErrInsufficientFunds = errors.New("insufficient funds for gas * price + value")
-
-	// ErrIntrinsicGas is returned if the transaction is specified to use less gas
-	// than required to start the invocation.
-	ErrIntrinsicGas = errors.New("intrinsic gas too low")
-
 	// ErrGasLimit is returned if a transaction's requested gas limit exceeds the
 	// maximum allowance of the current block.
 	ErrGasLimit = errors.New("exceeds block gas limit")
 
-	// ErrNegativeValue is a sanity error to ensure noone is able to specify a
+	// ErrNegativeValue is a sanity error to ensure no one is able to specify a
 	// transaction with a negative value.
 	ErrNegativeValue = errors.New("negative value")
 
@@ -95,15 +98,18 @@ var (
 	queuedReplaceMeter   = metrics.NewRegisteredMeter("txpool/queued/replace", nil)
 	queuedRateLimitMeter = metrics.NewRegisteredMeter("txpool/queued/ratelimit", nil) // Dropped due to rate limiting
 	queuedNofundsMeter   = metrics.NewRegisteredMeter("txpool/queued/nofunds", nil)   // Dropped due to out-of-funds
+	queuedEvictionMeter  = metrics.NewRegisteredMeter("txpool/queued/eviction", nil)  // Dropped due to lifetime
 
 	// General tx metrics
-	validMeter         = metrics.NewRegisteredMeter("txpool/valid", nil)
+	knownTxMeter       = metrics.NewRegisteredMeter("txpool/known", nil)
+	validTxMeter       = metrics.NewRegisteredMeter("txpool/valid", nil)
 	invalidTxMeter     = metrics.NewRegisteredMeter("txpool/invalid", nil)
 	underpricedTxMeter = metrics.NewRegisteredMeter("txpool/underpriced", nil)
 
-	pendingCounter = metrics.NewRegisteredCounter("txpool/pending", nil)
-	queuedCounter  = metrics.NewRegisteredCounter("txpool/queued", nil)
-	localCounter   = metrics.NewRegisteredCounter("txpool/local", nil)
+	pendingGauge = metrics.NewRegisteredGauge("txpool/pending", nil)
+	queuedGauge  = metrics.NewRegisteredGauge("txpool/queued", nil)
+	localGauge   = metrics.NewRegisteredGauge("txpool/local", nil)
+	slotsGauge   = metrics.NewRegisteredGauge("txpool/slots", nil)
 )
 
 // TxStatus is the current status of a transaction as seen by the pool.
@@ -359,9 +365,11 @@ func (pool *TxPool) loop() {
 				}
 				// Any non-locals old enough should be removed
 				if time.Since(pool.beats[addr]) > pool.config.Lifetime {
-					for _, tx := range pool.queue[addr].Flatten() {
+					list := pool.queue[addr].Flatten()
+					for _, tx := range list {
 						pool.removeTx(tx.Hash(), true)
 					}
+					queuedEvictionMeter.Mark(int64(len(list)))
 				}
 			}
 			pool.mu.Unlock()
@@ -517,8 +525,8 @@ func (pool *TxPool) local() map[common.Address]types.Transactions {
 // validateTx checks whether a transaction is valid according to the consensus
 // rules and adheres to some heuristic limits of the local node (price and size).
 func (pool *TxPool) validateTx(tx *types.Transaction, local bool) error {
-	// Heuristic limit, reject transactions over 32KB to prevent DOS attacks
-	if tx.Size() > 32*1024 {
+	// Reject transactions over defined size to prevent DOS attacks
+	if uint64(tx.Size()) > txMaxSize {
 		return ErrOversizedData
 	}
 	// Transactions can't be negative. This may never happen using RLP decoded
@@ -537,7 +545,7 @@ func (pool *TxPool) validateTx(tx *types.Transaction, local bool) error {
 	}
 	// Drop non-local transactions under our own minimal accepted gas price
 	local = local || pool.locals.contains(from) // account may be local even if the transaction arrived from the network
-	if !local && pool.gasPrice.Cmp(tx.GasPrice()) > 0 {
+	if !local && tx.GasPriceIntCmp(pool.gasPrice) < 0 {
 		return ErrUnderpriced
 	}
 	// Ensure the transaction adheres to nonce ordering
@@ -572,16 +580,15 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 	hash := tx.Hash()
 	if pool.all.Get(hash) != nil {
 		log.Trace("Discarding already known transaction", "hash", hash)
-		return false, fmt.Errorf("known transaction: %x", hash)
+		knownTxMeter.Mark(1)
+		return false, ErrAlreadyKnown
 	}
-
 	// If the transaction fails basic validation, discard it
 	if err := pool.validateTx(tx, local); err != nil {
 		log.Trace("Discarding invalid transaction", "hash", hash, "err", err)
 		invalidTxMeter.Mark(1)
 		return false, err
 	}
-
 	// If the transaction pool is full, discard underpriced transactions
 	if uint64(pool.all.Count()) >= pool.config.GlobalSlots+pool.config.GlobalQueue {
 		// If the new transaction is underpriced, don't accept it
@@ -591,14 +598,13 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 			return false, ErrUnderpriced
 		}
 		// New transaction is better than our worse ones, make room for it
-		drop := pool.priced.Discard(pool.all.Count()-int(pool.config.GlobalSlots+pool.config.GlobalQueue-1), pool.locals)
+		drop := pool.priced.Discard(pool.all.Slots()-int(pool.config.GlobalSlots+pool.config.GlobalQueue)+numSlots(tx), pool.locals)
 		for _, tx := range drop {
 			log.Trace("Discarding freshly underpriced transaction", "hash", tx.Hash(), "price", tx.GasPrice())
 			underpricedTxMeter.Mark(1)
 			pool.removeTx(tx.Hash(), false)
 		}
 	}
-
 	// Try to replace an existing transaction in the pending pool
 	from, _ := types.Sender(pool.signer, tx) // already validated
 	if list := pool.pending[from]; list != nil && list.Overlaps(tx) {
@@ -619,15 +625,16 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 		pool.journalTx(from, tx)
 		pool.queueTxEvent(tx)
 		log.Trace("Pooled new executable transaction", "hash", hash, "from", from, "to", tx.To())
+
+		// Successful promotion, bump the heartbeat
+		pool.beats[from] = time.Now()
 		return old != nil, nil
 	}
-
 	// New transaction isn't replacing a pending one, push into queue
 	replaced, err = pool.enqueueTx(hash, tx)
 	if err != nil {
 		return false, err
 	}
-
 	// Mark local addresses and journal local transactions
 	if local {
 		if !pool.locals.contains(from) {
@@ -636,7 +643,7 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 		}
 	}
 	if local || pool.locals.contains(from) {
-		localCounter.Inc(1)
+		localGauge.Inc(1)
 	}
 	pool.journalTx(from, tx)
 
@@ -666,12 +673,16 @@ func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) (bool, er
 		queuedReplaceMeter.Mark(1)
 	} else {
 		// Nothing was replaced, bump the queued counter
-		queuedCounter.Inc(1)
+		queuedGauge.Inc(1)
 	}
 	if pool.all.Get(hash) == nil {
 		pool.all.Add(tx)
 		pool.priced.Put(tx)
 	}
+	// If we never record the heartbeat, do it right now.
+	if _, exist := pool.beats[from]; !exist {
+		pool.beats[from] = time.Now()
+	}
 	return old != nil, nil
 }
 
@@ -703,7 +714,6 @@ func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.T
 		// An older transaction was better, discard this
 		pool.all.Remove(hash)
 		pool.priced.Removed(1)
-
 		pendingDiscardMeter.Mark(1)
 		return false
 	}
@@ -711,11 +721,10 @@ func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.T
 	if old != nil {
 		pool.all.Remove(old.Hash())
 		pool.priced.Removed(1)
-
 		pendingReplaceMeter.Mark(1)
 	} else {
 		// Nothing was replaced, bump the pending counter
-		pendingCounter.Inc(1)
+		pendingGauge.Inc(1)
 	}
 	// Failsafe to work around direct pending inserts (tests)
 	if pool.all.Get(hash) == nil {
@@ -723,9 +732,10 @@ func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.T
 		pool.priced.Put(tx)
 	}
 	// Set the potentially new pending nonce and notify any subsystems of the new tx
-	pool.beats[addr] = time.Now()
 	pool.pendingNonces.set(addr, tx.Nonce()+1)
 
+	// Successful promotion, bump the heartbeat
+	pool.beats[addr] = time.Now()
 	return true
 }
 
@@ -776,15 +786,47 @@ func (pool *TxPool) AddRemote(tx *types.Transaction) error {
 
 // addTxs attempts to queue a batch of transactions if they are valid.
 func (pool *TxPool) addTxs(txs []*types.Transaction, local, sync bool) []error {
-	// Cache senders in transactions before obtaining lock (pool.signer is immutable)
-	for _, tx := range txs {
-		types.Sender(pool.signer, tx)
+	// Filter out known ones without obtaining the pool lock or recovering signatures
+	var (
+		errs = make([]error, len(txs))
+		news = make([]*types.Transaction, 0, len(txs))
+	)
+	for i, tx := range txs {
+		// If the transaction is known, pre-set the error slot
+		if pool.all.Get(tx.Hash()) != nil {
+			errs[i] = ErrAlreadyKnown
+			knownTxMeter.Mark(1)
+			continue
+		}
+		// Exclude transactions with invalid signatures as soon as
+		// possible and cache senders in transactions before
+		// obtaining lock
+		_, err := types.Sender(pool.signer, tx)
+		if err != nil {
+			errs[i] = ErrInvalidSender
+			invalidTxMeter.Mark(1)
+			continue
+		}
+		// Accumulate all unknown transactions for deeper processing
+		news = append(news, tx)
+	}
+	if len(news) == 0 {
+		return errs
 	}
 
+	// Process all the new transaction and merge any errors into the original slice
 	pool.mu.Lock()
-	errs, dirtyAddrs := pool.addTxsLocked(txs, local)
+	newErrs, dirtyAddrs := pool.addTxsLocked(news, local)
 	pool.mu.Unlock()
 
+	var nilSlot = 0
+	for _, err := range newErrs {
+		for errs[nilSlot] != nil {
+			nilSlot++
+		}
+		errs[nilSlot] = err
+	}
+	// Reorg the pool internals if needed and return
 	done := pool.requestPromoteExecutables(dirtyAddrs)
 	if sync {
 		<-done
@@ -804,26 +846,29 @@ func (pool *TxPool) addTxsLocked(txs []*types.Transaction, local bool) ([]error,
 			dirty.addTx(tx)
 		}
 	}
-	validMeter.Mark(int64(len(dirty.accounts)))
+	validTxMeter.Mark(int64(len(dirty.accounts)))
 	return errs, dirty
 }
 
 // Status returns the status (unknown/pending/queued) of a batch of transactions
 // identified by their hashes.
 func (pool *TxPool) Status(hashes []common.Hash) []TxStatus {
-	pool.mu.RLock()
-	defer pool.mu.RUnlock()
-
 	status := make([]TxStatus, len(hashes))
 	for i, hash := range hashes {
-		if tx := pool.all.Get(hash); tx != nil {
-			from, _ := types.Sender(pool.signer, tx) // already validated
-			if pool.pending[from] != nil && pool.pending[from].txs.items[tx.Nonce()] != nil {
-				status[i] = TxStatusPending
-			} else {
-				status[i] = TxStatusQueued
-			}
+		tx := pool.Get(hash)
+		if tx == nil {
+			continue
+		}
+		from, _ := types.Sender(pool.signer, tx) // already validated
+		pool.mu.RLock()
+		if txList := pool.pending[from]; txList != nil && txList.txs.items[tx.Nonce()] != nil {
+			status[i] = TxStatusPending
+		} else if txList := pool.queue[from]; txList != nil && txList.txs.items[tx.Nonce()] != nil {
+			status[i] = TxStatusQueued
 		}
+		// implicit else: the tx may have been included into a block between
+		// checking pool.Get and obtaining the lock. In that case, TxStatusUnknown is correct
+		pool.mu.RUnlock()
 	}
 	return status
 }
@@ -833,6 +878,12 @@ func (pool *TxPool) Get(hash common.Hash) *types.Transaction {
 	return pool.all.Get(hash)
 }
 
+// Has returns an indicator whether txpool has a transaction cached with the
+// given hash.
+func (pool *TxPool) Has(hash common.Hash) bool {
+	return pool.all.Get(hash) != nil
+}
+
 // removeTx removes a single transaction from the queue, moving all subsequent
 // transactions back to the future queue.
 func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
@@ -849,7 +900,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 		pool.priced.Removed(1)
 	}
 	if pool.locals.contains(addr) {
-		localCounter.Dec(1)
+		localGauge.Dec(1)
 	}
 	// Remove the transaction from the pending lists and reset the account nonce
 	if pending := pool.pending[addr]; pending != nil {
@@ -857,7 +908,6 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 			// If no more pending transactions are left, remove the list
 			if pending.Empty() {
 				delete(pool.pending, addr)
-				delete(pool.beats, addr)
 			}
 			// Postpone any invalidated transactions
 			for _, tx := range invalids {
@@ -866,7 +916,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 			// Update the account nonce if needed
 			pool.pendingNonces.setIfLower(addr, tx.Nonce())
 			// Reduce the pending counter
-			pendingCounter.Dec(int64(1 + len(invalids)))
+			pendingGauge.Dec(int64(1 + len(invalids)))
 			return
 		}
 	}
@@ -874,10 +924,11 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 	if future := pool.queue[addr]; future != nil {
 		if removed, _ := future.Remove(tx); removed {
 			// Reduce the queued counter
-			queuedCounter.Dec(1)
+			queuedGauge.Dec(1)
 		}
 		if future.Empty() {
 			delete(pool.queue, addr)
+			delete(pool.beats, addr)
 		}
 	}
 }
@@ -989,7 +1040,10 @@ func (pool *TxPool) runReorg(done chan struct{}, reset *txpoolResetRequest, dirt
 	defer close(done)
 
 	var promoteAddrs []common.Address
-	if dirtyAccounts != nil {
+	if dirtyAccounts != nil && reset == nil {
+		// Only dirty accounts need to be promoted, unless we're resetting.
+		// For resets, all addresses in the tx queue will be promoted and
+		// the flatten operation can be avoided.
 		promoteAddrs = dirtyAccounts.flatten()
 	}
 	pool.mu.Lock()
@@ -1005,20 +1059,14 @@ func (pool *TxPool) runReorg(done chan struct{}, reset *txpoolResetRequest, dirt
 			}
 		}
 		// Reset needs promote for all addresses
-		promoteAddrs = promoteAddrs[:0]
+		promoteAddrs = make([]common.Address, 0, len(pool.queue))
 		for addr := range pool.queue {
 			promoteAddrs = append(promoteAddrs, addr)
 		}
 	}
 	// Check for pending transactions for every account that sent new ones
 	promoted := pool.promoteExecutables(promoteAddrs)
-	for _, tx := range promoted {
-		addr, _ := types.Sender(pool.signer, tx)
-		if _, ok := events[addr]; !ok {
-			events[addr] = newTxSortedMap()
-		}
-		events[addr].Put(tx)
-	}
+
 	// If a new block appeared, validate the pool of pending transactions. This will
 	// remove any transaction that has been included in the block or was invalidated
 	// because of another transaction (e.g. higher gas price).
@@ -1031,12 +1079,19 @@ func (pool *TxPool) runReorg(done chan struct{}, reset *txpoolResetRequest, dirt
 
 	// Update all accounts to the latest known pending nonce
 	for addr, list := range pool.pending {
-		txs := list.Flatten() // Heavy but will be cached and is needed by the miner anyway
-		pool.pendingNonces.set(addr, txs[len(txs)-1].Nonce()+1)
+		highestPending := list.LastElement()
+		pool.pendingNonces.set(addr, highestPending.Nonce()+1)
 	}
 	pool.mu.Unlock()
 
 	// Notify subsystems for newly added transactions
+	for _, tx := range promoted {
+		addr, _ := types.Sender(pool.signer, tx)
+		if _, ok := events[addr]; !ok {
+			events[addr] = newTxSortedMap()
+		}
+		events[addr].Put(tx)
+	}
 	if len(events) > 0 {
 		var txs []*types.Transaction
 		for _, set := range events {
@@ -1152,15 +1207,15 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) []*types.Trans
 		for _, tx := range forwards {
 			hash := tx.Hash()
 			pool.all.Remove(hash)
-			log.Trace("Removed old queued transaction", "hash", hash)
 		}
+		log.Trace("Removed old queued transactions", "count", len(forwards))
 		// Drop all transactions that are too costly (low balance or out of gas)
 		drops, _ := list.Filter(pool.currentState.GetBalance(addr), pool.currentMaxGas)
 		for _, tx := range drops {
 			hash := tx.Hash()
 			pool.all.Remove(hash)
-			log.Trace("Removed unpayable queued transaction", "hash", hash)
 		}
+		log.Trace("Removed unpayable queued transactions", "count", len(drops))
 		queuedNofundsMeter.Mark(int64(len(drops)))
 
 		// Gather all executable transactions and promote them
@@ -1168,11 +1223,11 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) []*types.Trans
 		for _, tx := range readies {
 			hash := tx.Hash()
 			if pool.promoteTx(addr, hash, tx) {
-				log.Trace("Promoting queued transaction", "hash", hash)
 				promoted = append(promoted, tx)
 			}
 		}
-		queuedCounter.Dec(int64(len(readies)))
+		log.Trace("Promoted queued transactions", "count", len(promoted))
+		queuedGauge.Dec(int64(len(readies)))
 
 		// Drop all transactions over the allowed limit
 		var caps types.Transactions
@@ -1187,13 +1242,14 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) []*types.Trans
 		}
 		// Mark all the items dropped as removed
 		pool.priced.Removed(len(forwards) + len(drops) + len(caps))
-		queuedCounter.Dec(int64(len(forwards) + len(drops) + len(caps)))
+		queuedGauge.Dec(int64(len(forwards) + len(drops) + len(caps)))
 		if pool.locals.contains(addr) {
-			localCounter.Dec(int64(len(forwards) + len(drops) + len(caps)))
+			localGauge.Dec(int64(len(forwards) + len(drops) + len(caps)))
 		}
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {
 			delete(pool.queue, addr)
+			delete(pool.beats, addr)
 		}
 	}
 	return promoted
@@ -1248,9 +1304,9 @@ func (pool *TxPool) truncatePending() {
 						log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 					}
 					pool.priced.Removed(len(caps))
-					pendingCounter.Dec(int64(len(caps)))
+					pendingGauge.Dec(int64(len(caps)))
 					if pool.locals.contains(offenders[i]) {
-						localCounter.Dec(int64(len(caps)))
+						localGauge.Dec(int64(len(caps)))
 					}
 					pending--
 				}
@@ -1275,9 +1331,9 @@ func (pool *TxPool) truncatePending() {
 					log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 				}
 				pool.priced.Removed(len(caps))
-				pendingCounter.Dec(int64(len(caps)))
+				pendingGauge.Dec(int64(len(caps)))
 				if pool.locals.contains(addr) {
-					localCounter.Dec(int64(len(caps)))
+					localGauge.Dec(int64(len(caps)))
 				}
 				pending--
 			}
@@ -1361,9 +1417,9 @@ func (pool *TxPool) demoteUnexecutables() {
 			log.Trace("Demoting pending transaction", "hash", hash)
 			pool.enqueueTx(hash, tx)
 		}
-		pendingCounter.Dec(int64(len(olds) + len(drops) + len(invalids)))
+		pendingGauge.Dec(int64(len(olds) + len(drops) + len(invalids)))
 		if pool.locals.contains(addr) {
-			localCounter.Dec(int64(len(olds) + len(drops) + len(invalids)))
+			localGauge.Dec(int64(len(olds) + len(drops) + len(invalids)))
 		}
 		// If there's a gap in front, alert (should never happen) and postpone all transactions
 		if list.Len() > 0 && list.txs.Get(nonce) == nil {
@@ -1373,12 +1429,13 @@ func (pool *TxPool) demoteUnexecutables() {
 				log.Error("Demoting invalidated transaction", "hash", hash)
 				pool.enqueueTx(hash, tx)
 			}
-			pendingCounter.Dec(int64(len(gapped)))
+			pendingGauge.Dec(int64(len(gapped)))
+			// This might happen in a reorg, so log it to the metering
+			blockReorgInvalidatedTx.Mark(int64(len(gapped)))
 		}
-		// Delete the entire queue entry if it became empty.
+		// Delete the entire pending entry if it became empty.
 		if list.Empty() {
 			delete(pool.pending, addr)
-			delete(pool.beats, addr)
 		}
 	}
 }
@@ -1422,6 +1479,10 @@ func (as *accountSet) contains(addr common.Address) bool {
 	return exist
 }
 
+func (as *accountSet) empty() bool {
+	return len(as.accounts) == 0
+}
+
 // containsTx checks if the sender of a given tx is within the set. If the sender
 // cannot be derived, this method returns false.
 func (as *accountSet) containsTx(tx *types.Transaction) bool {
@@ -1475,8 +1536,9 @@ func (as *accountSet) merge(other *accountSet) {
 // peeking into the pool in TxPool.Get without having to acquire the widely scoped
 // TxPool.mu mutex.
 type txLookup struct {
-	all  map[common.Hash]*types.Transaction
-	lock sync.RWMutex
+	all   map[common.Hash]*types.Transaction
+	slots int
+	lock  sync.RWMutex
 }
 
 // newTxLookup returns a new txLookup structure.
@@ -1514,11 +1576,22 @@ func (t *txLookup) Count() int {
 	return len(t.all)
 }
 
+// Slots returns the current number of slots used in the lookup.
+func (t *txLookup) Slots() int {
+	t.lock.RLock()
+	defer t.lock.RUnlock()
+
+	return t.slots
+}
+
 // Add adds a transaction to the lookup.
 func (t *txLookup) Add(tx *types.Transaction) {
 	t.lock.Lock()
 	defer t.lock.Unlock()
 
+	t.slots += numSlots(tx)
+	slotsGauge.Update(int64(t.slots))
+
 	t.all[tx.Hash()] = tx
 }
 
@@ -1527,5 +1600,13 @@ func (t *txLookup) Remove(hash common.Hash) {
 	t.lock.Lock()
 	defer t.lock.Unlock()
 
+	t.slots -= numSlots(t.all[hash])
+	slotsGauge.Update(int64(t.slots))
+
 	delete(t.all, hash)
 }
+
+// numSlots calculates the number of slots needed for a single transaction.
+func numSlots(tx *types.Transaction) int {
+	return int((tx.Size() + txSlotSize - 1) / txSlotSize)
+}