From 786298469cf001b3a59f66e8309ca9d4740aba05 Mon Sep 17 00:00:00 2001
From: Derek Collison <derek@nats.io>
Date: Wed, 14 Dec 2022 18:52:15 -0800
Subject: [PATCH] Simplify locking for consumer info requests.

Signed-off-by: Derek Collison <derek@nats.io>
---
 server/consumer.go | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/server/consumer.go b/server/consumer.go
index 2240bf2f2f..aceaf5904b 100644
--- a/server/consumer.go
+++ b/server/consumer.go
@@ -1122,10 +1122,7 @@ func (o *consumer) setLeader(isLeader bool) {
 }
 
 func (o *consumer) handleClusterConsumerInfoRequest(sub *subscription, c *client, _ *Account, subject, reply string, msg []byte) {
-	o.mu.RLock()
-	sysc := o.sysc
-	o.mu.RUnlock()
-	sysc.sendInternalMsg(reply, _EMPTY_, nil, o.info())
+	o.infoWithSnapAndReply(false, reply)
 }
 
 // Lock should be held.
@@ -2202,23 +2199,27 @@ func (o *consumer) info() *ConsumerInfo {
 }
 
 func (o *consumer) infoWithSnap(snap bool) *ConsumerInfo {
-	o.mu.RLock()
+	return o.infoWithSnapAndReply(snap, _EMPTY_)
+}
+
+func (o *consumer) infoWithSnapAndReply(snap bool, reply string) *ConsumerInfo {
+	o.mu.Lock()
 	mset := o.mset
 	if mset == nil || mset.srv == nil {
-		o.mu.RUnlock()
+		o.mu.Unlock()
 		return nil
 	}
 	js := o.js
-	o.mu.RUnlock()
-
 	if js == nil {
+		o.mu.Unlock()
 		return nil
 	}
 
-	ci := js.clusterInfo(o.raftGroup())
-
-	o.mu.Lock()
-	defer o.mu.Unlock()
+	// Capture raftGroup.
+	var rg *raftGroup
+	if o.ca != nil {
+		rg = o.ca.Group
+	}
 
 	cfg := o.cfg
 	info := &ConsumerInfo{
@@ -2238,7 +2239,6 @@ func (o *consumer) infoWithSnap(snap bool) *ConsumerInfo {
 		NumRedelivered: len(o.rdc),
 		NumPending:     o.streamNumPending(),
 		PushBound:      o.isPushMode() && o.active,
-		Cluster:        ci,
 	}
 	// Adjust active based on non-zero etc. Also make UTC here.
 	if !o.ldt.IsZero() {
@@ -2259,6 +2259,18 @@ func (o *consumer) infoWithSnap(snap bool) *ConsumerInfo {
 	if snap {
 		o.ici = info
 	}
+	sysc := o.sysc
+	o.mu.Unlock()
+
+	// Do cluster.
+	if rg != nil {
+		info.Cluster = js.clusterInfo(rg)
+	}
+
+	// If we have a reply subject send the response here.
+	if reply != _EMPTY_ && sysc != nil {
+		sysc.sendInternalMsg(reply, _EMPTY_, nil, info)
+	}
 
 	return info
 }