[iotdb] branch master updated: Add comment on getLeader (#6371)

[tanxinyu]

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tanxinyu pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/iotdb.git


The following commit(s) were added to refs/heads/master by this push:
     new fbb74cd83e Add comment on getLeader (#6371)
fbb74cd83e is described below

commit fbb74cd83e9dce402d876d34be9e01de6c9ad56d
Author: William Song <48054931+szywill...@users.noreply.github.com>
AuthorDate: Wed Jun 22 00:11:19 2022 +0800

    Add comment on getLeader (#6371)
    
    * add comment on getLeader
    
    * add comment on getLeader
---
 .../java/org/apache/iotdb/consensus/ratis/RatisConsensus.java    | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git 
a/consensus/src/main/java/org/apache/iotdb/consensus/ratis/RatisConsensus.java 
b/consensus/src/main/java/org/apache/iotdb/consensus/ratis/RatisConsensus.java
index 33a523eb06..82418e7740 100644
--- 
a/consensus/src/main/java/org/apache/iotdb/consensus/ratis/RatisConsensus.java
+++ 
b/consensus/src/main/java/org/apache/iotdb/consensus/ratis/RatisConsensus.java
@@ -515,6 +515,12 @@ class RatisConsensus implements IConsensus {
     return divisionInfo.isLeader();
   }
 
+  /**
+   * returns the known leader to the given group. NOTICE: if the local peer 
isn't a member of given
+   * group, getLeader will return null.
+   *
+   * @return null if local peer isn't in group, otherwise group leader.
+   */
   @Override
   public Peer getLeader(ConsensusGroupId groupId) {
     RaftGroupId raftGroupId = Utils.fromConsensusGroupIdToRaftGroupId(groupId);
@@ -526,6 +532,9 @@ class RatisConsensus implements IConsensus {
       logger.warn("fetch division info for group " + groupId + " failed due 
to: ", e);
       return null;
     }
+    if (leaderId == null) {
+      return null;
+    }
     TEndPoint leaderEndpoint = Utils.formRaftPeerIdToTEndPoint(leaderId);
     return new Peer(groupId, leaderEndpoint);
   }