(ratis) 03/12: RATIS-2008. Follower should recognize candidate if the candidate is the same peer as the current valid leader (#1024)

[wi...@apache.org]

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williamsong pushed a commit to branch snapshot-3
in repository https://gitbox.apache.org/repos/asf/ratis.git

commit f8f12d8908e1eabbee3f12f9e84c00c1132345b8
Author: Ivan Andika <36...@users.noreply.github.com>
AuthorDate: Thu Jan 25 01:14:49 2024 +0800

    RATIS-2008. Follower should recognize candidate if the candidate is the same peer as the current valid leader (#1024)
---
 .../src/main/java/org/apache/ratis/server/impl/VoteContext.java       | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/ratis-server/src/main/java/org/apache/ratis/server/impl/VoteContext.java b/ratis-server/src/main/java/org/apache/ratis/server/impl/VoteContext.java
index 6375d652c..3ba0c0e01 100644
--- a/ratis-server/src/main/java/org/apache/ratis/server/impl/VoteContext.java
+++ b/ratis-server/src/main/java/org/apache/ratis/server/impl/VoteContext.java
@@ -102,8 +102,10 @@ class VoteContext {
     if (info.isFollower()) {
       final RaftPeerId leader = impl.getState().getLeaderId();
       if (leader != null
+          && !leader.equals(candidateId)
           && impl.getRole().getFollowerState().map(FollowerState::isCurrentLeaderValid).orElse(false)) {
-        return reject("this server is a follower and still has a valid leader " + leader);
+        return reject("this server is a follower and still has a valid leader " + leader
+            + " different than the candidate " + candidateId);
       }
     }
     return true;