Follow up https://github.com/etcd-io/etcd/pull/16068#discussion_r1263664700

Replace unnecessary Lock()/Unlock()s with RLock()/RUnlock()s

Signed-off-by: caojiamingalan <alan.c.19971111@gmail.com>

server/storage/schema/alarm.go

@@ -74,8 +74,8 @@ func (s *alarmBackend) mustUnsafeDeleteAlarm(tx backend.BatchTx, alarm *etcdserv
 
 func (s *alarmBackend) GetAllAlarms() ([]*etcdserverpb.AlarmMember, error) {
 	tx := s.be.ReadTx()
-	tx.Lock()
-	defer tx.Unlock()
+	tx.RLock()
+	defer tx.RUnlock()
 	return s.unsafeGetAllAlarms(tx)
 }
 

server/storage/schema/membership.go

@@ -207,8 +207,8 @@ func (s *membershipBackend) ClusterVersionFromBackend() *semver.Version {
 func (s *membershipBackend) DowngradeInfoFromBackend() *version.DowngradeInfo {
 	dkey := ClusterDowngradeKeyName
 	tx := s.be.ReadTx()
-	tx.Lock()
-	defer tx.Unlock()
+	tx.RLock()
+	defer tx.RUnlock()
 	keys, vals := tx.UnsafeRange(Cluster, dkey, nil, 0)
 	if len(keys) == 0 {
 		return nil

server/storage/schema/schema.go

@@ -27,8 +27,8 @@ import (
 
 // Validate checks provided backend to confirm that schema used is supported.
 func Validate(lg *zap.Logger, tx backend.ReadTx) error {
-	tx.Lock()
-	defer tx.Unlock()
+	tx.RLock()
+	defer tx.RUnlock()
 	return unsafeValidate(lg, tx)
 }
 

server/storage/schema/version.go

@@ -24,8 +24,8 @@ import (
 // ReadStorageVersion loads storage version from given backend transaction.
 // Populated since v3.6
 func ReadStorageVersion(tx backend.ReadTx) *semver.Version {
-	tx.Lock()
-	defer tx.Unlock()
+	tx.RLock()
+	defer tx.RUnlock()
 	return UnsafeReadStorageVersion(tx)
 }