Re-introduce atomics from #6176

Signed-off-by: Maurice van Veen <github@mauricevanveen.com>

server/jetstream.go

@@ -461,6 +461,8 @@ func (s *Server) enableJetStream(cfg JetStreamConfig) error {
 		if err := s.enableJetStreamClustering(); err != nil {
 			return err
 		}
+		// Set our atomic bool to clustered.
+		s.jsClustered.Store(true)
 	}
 
 	// Mark when we are up and running.
@@ -965,6 +967,8 @@ func (s *Server) shutdownJetStream() {
 			cc.c = nil
 		}
 		cc.meta = nil
+		// Set our atomic bool to false.
+		s.jsClustered.Store(false)
 	}
 	js.mu.Unlock()
 

server/jetstream_cluster.go

@@ -224,11 +224,7 @@ func (s *Server) getJetStreamCluster() (*jetStream, *jetStreamCluster) {
 }
 
 func (s *Server) JetStreamIsClustered() bool {
-	js := s.getJetStream()
-	if js == nil {
-		return false
-	}
-	return js.isClustered()
+	return s.jsClustered.Load()
 }
 
 func (s *Server) JetStreamIsLeader() bool {

server/server.go

@@ -141,8 +141,10 @@ type Server struct {
 	listenerErr         error
 	gacc                *Account
 	sys                 *internal
+	sysAcc              atomic.Pointer[Account]
 	js                  atomic.Pointer[jetStream]
 	isMetaLeader        atomic.Bool
+	jsClustered         atomic.Bool
 	accounts            sync.Map
 	tmpAccounts         sync.Map // Temporarily stores accounts that are being built
 	activeAccounts      int32
@@ -1281,6 +1283,7 @@ func (s *Server) configureAccounts(reloading bool) (map[string]struct{}, error)
 		if err == nil && s.sys != nil && acc != s.sys.account {
 			// sys.account.clients (including internal client)/respmap/etc... are transferred separately
 			s.sys.account = acc
+			s.sysAcc.Store(acc)
 		}
 		if err != nil {
 			return awcsti, fmt.Errorf("error resolving system account: %v", err)
@@ -1636,13 +1639,7 @@ func (s *Server) SetSystemAccount(accName string) error {
 
 // SystemAccount returns the system account if set.
 func (s *Server) SystemAccount() *Account {
-	var sacc *Account
-	s.mu.RLock()
-	if s.sys != nil {
-		sacc = s.sys.account
-	}
-	s.mu.RUnlock()
-	return sacc
+	return s.sysAcc.Load()
 }
 
 // GlobalAccount returns the global account.
@@ -1714,6 +1711,9 @@ func (s *Server) setSystemAccount(acc *Account) error {
 	s.sys.wg.Add(1)
 	s.mu.Unlock()
 
+	// Store in atomic for fast lookup.
+	s.sysAcc.Store(acc)
+
 	// Register with the account.
 	s.sys.client.registerWithAccount(acc)