From 642a6e0820810cc3baf5f89c6863a27e32ad040e Mon Sep 17 00:00:00 2001
From: Benjamin Wang <wachao@vmware.com>
Date: Wed, 27 Sep 2023 17:53:22 +0100
Subject: [PATCH] Do not update RaftCluster.members and RaftCluster.removed if
 the v3store is ahead of the current replayed WAL entry index

Signed-off-by: Benjamin Wang <wachao@vmware.com>
---
 server/etcdserver/api/membership/cluster.go | 81 +++++++++++++--------
 1 file changed, 50 insertions(+), 31 deletions(-)

diff --git a/server/etcdserver/api/membership/cluster.go b/server/etcdserver/api/membership/cluster.go
index fe657fb86900..57e3d2358385 100644
--- a/server/etcdserver/api/membership/cluster.go
+++ b/server/etcdserver/api/membership/cluster.go
@@ -395,19 +395,27 @@ func (c *RaftCluster) AddMember(m *Member, shouldApplyV3 ShouldApplyV3) {
 	}
 	if c.be != nil && shouldApplyV3 {
 		c.be.MustSaveMemberToBackend(m)
-	}
 
-	c.members[m.ID] = m
-	c.updateMembershipMetric(m.ID, true)
+		c.members[m.ID] = m
+		c.updateMembershipMetric(m.ID, true)
 
-	c.lg.Info(
-		"added member",
-		zap.String("cluster-id", c.cid.String()),
-		zap.String("local-member-id", c.localID.String()),
-		zap.String("added-peer-id", m.ID.String()),
-		zap.Strings("added-peer-peer-urls", m.PeerURLs),
-		zap.Bool("added-peer-is-learner", m.IsLearner),
-	)
+		c.lg.Info(
+			"added member",
+			zap.String("cluster-id", c.cid.String()),
+			zap.String("local-member-id", c.localID.String()),
+			zap.String("added-peer-id", m.ID.String()),
+			zap.Strings("added-peer-peer-urls", m.PeerURLs),
+			zap.Bool("added-peer-is-learner", m.IsLearner),
+		)
+	} else {
+		c.lg.Info(
+			"ignore already added member",
+			zap.String("cluster-id", c.cid.String()),
+			zap.String("local-member-id", c.localID.String()),
+			zap.String("added-peer-id", m.ID.String()),
+			zap.Strings("added-peer-peer-urls", m.PeerURLs),
+			zap.Bool("added-peer-is-learner", m.IsLearner))
+	}
 }
 
 // RemoveMember removes a member from the store.
@@ -420,25 +428,32 @@ func (c *RaftCluster) RemoveMember(id types.ID, shouldApplyV3 ShouldApplyV3) {
 	}
 	if c.be != nil && shouldApplyV3 {
 		c.be.MustDeleteMemberFromBackend(id)
-	}
 
-	m, ok := c.members[id]
-	delete(c.members, id)
-	c.removed[id] = true
-	c.updateMembershipMetric(id, false)
-
-	if ok {
-		c.lg.Info(
-			"removed member",
-			zap.String("cluster-id", c.cid.String()),
-			zap.String("local-member-id", c.localID.String()),
-			zap.String("removed-remote-peer-id", id.String()),
-			zap.Strings("removed-remote-peer-urls", m.PeerURLs),
-			zap.Bool("removed-remote-peer-is-learner", m.IsLearner),
-		)
+		m, ok := c.members[id]
+		delete(c.members, id)
+		c.removed[id] = true
+		c.updateMembershipMetric(id, false)
+
+		if ok {
+			c.lg.Info(
+				"removed member",
+				zap.String("cluster-id", c.cid.String()),
+				zap.String("local-member-id", c.localID.String()),
+				zap.String("removed-remote-peer-id", id.String()),
+				zap.Strings("removed-remote-peer-urls", m.PeerURLs),
+				zap.Bool("removed-remote-peer-is-learner", m.IsLearner),
+			)
+		} else {
+			c.lg.Warn(
+				"skipped removing already removed member",
+				zap.String("cluster-id", c.cid.String()),
+				zap.String("local-member-id", c.localID.String()),
+				zap.String("removed-remote-peer-id", id.String()),
+			)
+		}
 	} else {
-		c.lg.Warn(
-			"skipped removing already removed member",
+		c.lg.Info(
+			"ignore already removed member",
 			zap.String("cluster-id", c.cid.String()),
 			zap.String("local-member-id", c.localID.String()),
 			zap.String("removed-remote-peer-id", id.String()),
@@ -484,8 +499,10 @@ func (c *RaftCluster) PromoteMember(id types.ID, shouldApplyV3 ShouldApplyV3) {
 	c.Lock()
 	defer c.Unlock()
 
-	c.members[id].RaftAttributes.IsLearner = false
-	c.updateMembershipMetric(id, true)
+	if _, ok := c.members[id]; ok {
+		c.members[id].RaftAttributes.IsLearner = false
+		c.updateMembershipMetric(id, true)
+	}
 	if c.v2store != nil {
 		mustUpdateMemberInStore(c.lg, c.v2store, c.members[id])
 	}
@@ -504,7 +521,9 @@ func (c *RaftCluster) UpdateRaftAttributes(id types.ID, raftAttr RaftAttributes,
 	c.Lock()
 	defer c.Unlock()
 
-	c.members[id].RaftAttributes = raftAttr
+	if _, ok := c.members[id]; ok {
+		c.members[id].RaftAttributes = raftAttr
+	}
 	if c.v2store != nil {
 		mustUpdateMemberInStore(c.lg, c.v2store, c.members[id])
 	}