core/txpool: simplify loop, implement AppendHashes

core/txpool/blobpool/blobpool.go

@@ -1481,7 +1481,6 @@ func (p *BlobPool) Pending(filter txpool.PendingFilter) txpool.Pending {
 	for addr, txs := range p.index {
 		var (
 			tail []*txpool.LazyTransaction
-			first = true
 		)
 		for i, tx := range txs {
 			var tip *uint256.Int
@@ -1513,8 +1512,7 @@ func (p *BlobPool) Pending(filter txpool.PendingFilter) txpool.Pending {
 				Gas:     tx.execGas,
 				BlobGas: tx.blobGas,
 			}
-			if first {
-				first = false
+			if len(tail) == 0 {
 				tail = make([]*txpool.LazyTransaction, 0, len(txs)-i)
 				heads = append(heads, &txpool.TxTips{
 					From: addr,

core/txpool/legacypool/legacypool.go

@@ -550,7 +550,6 @@ func (pool *LegacyPool) Pending(filter txpool.PendingFilter) txpool.Pending {
 		}
 		var (
 			tail []*txpool.LazyTransaction
-			first = true
 			txs  = list.Flatten()
 		)
 		for i, tx := range txs {
@@ -575,8 +574,7 @@ func (pool *LegacyPool) Pending(filter txpool.PendingFilter) txpool.Pending {
 				Gas:     txs[i].Gas(),
 				BlobGas: txs[i].BlobGas(),
 			}
-			if first {
-				first = false
+			if len(tail) == 0 {
 				tail = make([]*txpool.LazyTransaction, 0, len(txs)-i)
 				heads = append(heads, &txpool.TxTips{
 					From: addr,
@@ -610,9 +608,7 @@ func (pool *LegacyPool) PendingHashes(filter txpool.PendingFilter) []common.Hash
 		if filter.OnlyLocals && !pool.locals.contains(addr) {
 			continue
 		}
-		for _, tx := range list.Flatten() {
-			hashes = append(hashes, tx.Hash())
-		}
+		hashes = list.AppendHashes(hashes)
 	}
 	return hashes
 }

core/txpool/legacypool/list.go

@@ -258,6 +258,25 @@ func (m *sortedMap) Flatten() types.Transactions {
 	return txs
 }
 
+// AppendHashes uses the flattened slice of transactions and appends the hashes
+// to the destination slice.
+func (m *sortedMap) AppendHashes(dst []common.Hash) []common.Hash {
+	m.cacheMu.Lock()
+	defer m.cacheMu.Unlock()
+	// If the sorting was not cached yet, create and cache it
+	if m.cache == nil {
+		m.cache = make(types.Transactions, 0, len(m.items))
+		for _, tx := range m.items {
+			m.cache = append(m.cache, tx)
+		}
+		sort.Sort(types.TxByNonce(m.cache))
+	}
+	for _, tx := range m.items {
+		dst = append(dst, tx.Hash())
+	}
+	return dst
+}
+
 // LastElement returns the last element of a flattened list, thus, the
 // transaction with the highest nonce
 func (m *sortedMap) LastElement() *types.Transaction {
@@ -453,6 +472,12 @@ func (l *list) Flatten() types.Transactions {
 	return l.txs.Flatten()
 }
 
+// AppendHashes flattens a nonce-sorted slice of transcations, and appends
+// the hashes to dst. The destination slice might be reallocated, and is returned.
+func (l *list) AppendHashes(dst []common.Hash) []common.Hash {
+	return l.txs.AppendHashes(dst)
+}
+
 // LastElement returns the last element of a flattened list, thus, the
 // transaction with the highest nonce
 func (l *list) LastElement() *types.Transaction {