core/txpool/legacypool: use maps.Keys and maps.Copy (#30091)

core/txpool/legacypool/legacypool.go

@@ -38,6 +38,7 @@ import (
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/holiman/uint256"
+	"golang.org/x/exp/maps"
 )
 
 const (
@@ -1717,7 +1718,7 @@ func (a addressesByHeartbeat) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 type accountSet struct {
 	accounts map[common.Address]struct{}
 	signer   types.Signer
-	cache    *[]common.Address
+	cache    []common.Address
 }
 
 // newAccountSet creates a new address set with an associated signer for sender
@@ -1765,20 +1766,14 @@ func (as *accountSet) addTx(tx *types.Transaction) {
 // reuse. The returned slice should not be changed!
 func (as *accountSet) flatten() []common.Address {
 	if as.cache == nil {
-		accounts := make([]common.Address, 0, len(as.accounts))
-		for account := range as.accounts {
-			accounts = append(accounts, account)
+		as.cache = maps.Keys(as.accounts)
 	}
-		as.cache = &accounts
-	}
-	return *as.cache
+	return as.cache
 }
 
 // merge adds all addresses from the 'other' set into 'as'.
 func (as *accountSet) merge(other *accountSet) {
-	for addr := range other.accounts {
-		as.accounts[addr] = struct{}{}
-	}
+	maps.Copy(as.accounts, other.accounts)
 	as.cache = nil
 }