From 573f78c308332c083fa216a7fde4ef1913b60ffe Mon Sep 17 00:00:00 2001
From: RS146BIJAY <rishavsagar4b1@gmail.com>
Date: Thu, 22 Aug 2024 11:38:32 +0530
Subject: [PATCH] Skipping serialization of node attributes in Leader and
 follower checks

Signed-off-by: RS146BIJAY <rishavsagar4b1@gmail.com>
---
 .../coordination/FollowersChecker.java        |  2 +-
 .../cluster/coordination/LeaderChecker.java   |  2 +-
 .../cluster/node/DiscoveryNode.java           | 27 ++++++++++++++++---
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java b/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java
index 2ec0dabd91786..be8d4ba209e7d 100644
--- a/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java
+++ b/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java
@@ -503,7 +503,7 @@ public FollowerCheckRequest(final StreamInput in) throws IOException {
         public void writeTo(final StreamOutput out) throws IOException {
             super.writeTo(out);
             out.writeLong(term);
-            sender.writeTo(out);
+            sender.writeToWithoutAttribute(out);
         }
 
         @Override
diff --git a/server/src/main/java/org/opensearch/cluster/coordination/LeaderChecker.java b/server/src/main/java/org/opensearch/cluster/coordination/LeaderChecker.java
index 4fd2c0eb13073..41b6e32bb500d 100644
--- a/server/src/main/java/org/opensearch/cluster/coordination/LeaderChecker.java
+++ b/server/src/main/java/org/opensearch/cluster/coordination/LeaderChecker.java
@@ -416,7 +416,7 @@ static class LeaderCheckRequest extends TransportRequest {
         @Override
         public void writeTo(final StreamOutput out) throws IOException {
             super.writeTo(out);
-            sender.writeTo(out);
+            sender.writeToWithoutAttribute(out);
         }
 
         public DiscoveryNode getSender() {
diff --git a/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java b/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java
index 653f81830ed17..76b4c483ab50e 100644
--- a/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java
+++ b/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java
@@ -358,17 +358,36 @@ public DiscoveryNode(StreamInput in) throws IOException {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
+        writeToUtil(out, true);
+    }
+
+    public void writeToWithoutAttribute(StreamOutput out) throws IOException {
+        if (out.getVersion().onOrAfter(Version.V_2_16_0)) {
+            writeToUtil(out, false);
+        } else {
+            writeToUtil(out, true);
+        }
+
+    }
+
+    private void writeToUtil(StreamOutput out, boolean includeAttributes) throws IOException {
         out.writeString(nodeName);
         out.writeString(nodeId);
         out.writeString(ephemeralId);
         out.writeString(hostName);
         out.writeString(hostAddress);
         address.writeTo(out);
-        out.writeVInt(attributes.size());
-        for (Map.Entry<String, String> entry : attributes.entrySet()) {
-            out.writeString(entry.getKey());
-            out.writeString(entry.getValue());
+        if (includeAttributes) {
+            out.writeVInt(attributes.size());
+            for (Map.Entry<String, String> entry : attributes.entrySet()) {
+                out.writeString(entry.getKey());
+                out.writeString(entry.getValue());
+            }
+        } else {
+            // Set the size of attribute as 0 so that no attribute is read from stream on receiver node.
+            out.writeVInt(0);
         }
+
         out.writeVInt(roles.size());
         for (final DiscoveryNodeRole role : roles) {
             final DiscoveryNodeRole compatibleRole = role.getCompatibilityRole(out.getVersion());