From bee149b45805cffda219ca1c85fa37031bea2d2c Mon Sep 17 00:00:00 2001
From: Derek Collison <derek@nats.io>
Date: Mon, 27 Feb 2023 17:49:00 -0800
Subject: [PATCH] Only need server's rlock here.

Signed-off-by: Derek Collison <derek@nats.io>
---
 server/jetstream.go         |  4 ++--
 server/jetstream_api.go     | 20 +++++++++++---------
 server/jetstream_cluster.go | 27 ++++++++++++++++++++++-----
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/server/jetstream.go b/server/jetstream.go
index 78f4e00c..fd7926f0 100644
--- a/server/jetstream.go
+++ b/server/jetstream.go
@@ -784,9 +784,9 @@ func (js *jetStream) setJetStreamStandAlone(isStandAlone bool) {
 // JetStreamEnabled reports if jetstream is enabled for this server.
 func (s *Server) JetStreamEnabled() bool {
 	var js *jetStream
-	s.mu.Lock()
+	s.mu.RLock()
 	js = s.js
-	s.mu.Unlock()
+	s.mu.RUnlock()
 	return js.isEnabled()
 }
 
diff --git a/server/jetstream_api.go b/server/jetstream_api.go
index cfe06442..890b41a3 100644
--- a/server/jetstream_api.go
+++ b/server/jetstream_api.go
@@ -1591,9 +1591,14 @@ func (s *Server) jsStreamNamesRequest(sub *subscription, c *client, _ *Account,
 // Request for the list of all detailed stream info.
 // TODO(dlc) - combine with above long term
 func (s *Server) jsStreamListRequest(sub *subscription, c *client, _ *Account, subject, reply string, rmsg []byte) {
-	if c == nil || !s.JetStreamEnabled() {
+	if c == nil {
 		return
 	}
+	js, cc := s.getJetStreamCluster()
+	if js == nil {
+		return
+	}
+
 	ci, acc, _, msg, err := s.getRequestInfo(c, rmsg)
 	if err != nil {
 		s.Warnf(badAPIRequestT, msg)
@@ -1606,18 +1611,15 @@ func (s *Server) jsStreamListRequest(sub *subscription, c *client, _ *Account, s
 	}
 
 	// Determine if we should proceed here when we are in clustered mode.
-	if s.JetStreamIsClustered() {
-		js, cc := s.getJetStreamCluster()
-		if js == nil || cc == nil {
-			return
-		}
-		if js.isLeaderless() {
+	if cc != nil {
+		leader, leaderless := js.leaderStatus()
+		if leaderless {
 			resp.Error = NewJSClusterNotAvailError()
 			s.sendAPIErrResponse(ci, acc, subject, reply, string(msg), s.jsonResponse(&resp))
 			return
 		}
 		// Make sure we are meta leader.
-		if !s.JetStreamIsLeader() {
+		if !leader {
 			return
 		}
 	}
@@ -1647,7 +1649,7 @@ func (s *Server) jsStreamListRequest(sub *subscription, c *client, _ *Account, s
 	}
 
 	// Clustered mode will invoke a scatter and gather.
-	if s.JetStreamIsClustered() {
+	if cc != nil {
 		// Need to copy these off before sending.. don't move this inside startGoRoutine!!!
 		msg = copyBytes(msg)
 		s.startGoRoutine(func() { s.jsClusteredStreamListRequest(acc, ci, filter, offset, subject, reply, msg) })
diff --git a/server/jetstream_cluster.go b/server/jetstream_cluster.go
index 268030a3..57dd718e 100644
--- a/server/jetstream_cluster.go
+++ b/server/jetstream_cluster.go
@@ -206,11 +206,7 @@ func (s *Server) getJetStreamCluster() (*jetStream, *jetStreamCluster) {
 	}
 
 	// Only set once, do not need a lock.
-	cc := js.cluster
-	if cc == nil {
-		return nil, nil
-	}
-	return js, cc
+	return js, js.cluster
 }
 
 func (s *Server) JetStreamIsClustered() bool {
@@ -717,6 +713,27 @@ func (js *jetStream) server() *Server {
 	return s
 }
 
+// Returns leader status, both whether or not we are the leader and if the group is leaderless.
+func (js *jetStream) leaderStatus() (bool, bool) {
+	js.mu.RLock()
+	defer js.mu.RUnlock()
+
+	cc := js.cluster
+	if cc == nil || cc.meta == nil {
+		return false, true
+	}
+	isLeader := cc.meta.Leader()
+	if isLeader {
+		return true, false
+	}
+	// If we don't have a leader.
+	// Make sure we have been running for enough time.
+	if cc.meta.GroupLeader() == _EMPTY_ && time.Since(cc.meta.Created()) > lostQuorumIntervalDefault {
+		return false, true
+	}
+	return false, false
+}
+
 // Will respond if we do not think we have a metacontroller leader.
 func (js *jetStream) isLeaderless() bool {
 	js.mu.RLock()