From 56d65c413312577e704eeedb4cea1cc2e229847e 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        |  7 +++-
 .../cluster/node/DiscoveryNode.java           | 38 ++++++++++++++++---
 2 files changed, 38 insertions(+), 7 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..2cee9b1c2ee33 100644
--- a/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java
+++ b/server/src/main/java/org/opensearch/cluster/coordination/FollowersChecker.java
@@ -35,6 +35,7 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.ParameterizedMessage;
+import org.opensearch.Version;
 import org.opensearch.cluster.ClusterManagerMetrics;
 import org.opensearch.cluster.coordination.Coordinator.Mode;
 import org.opensearch.cluster.node.DiscoveryNode;
@@ -503,7 +504,11 @@ public FollowerCheckRequest(final StreamInput in) throws IOException {
         public void writeTo(final StreamOutput out) throws IOException {
             super.writeTo(out);
             out.writeLong(term);
-            sender.writeTo(out);
+            if (out.getVersion().onOrAfter(Version.V_3_0_0)) {
+                sender.writeToWithoutAttribute(out);
+            } else {
+                sender.writeTo(out);
+            }
         }
 
         @Override
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..2926e67d7d67b 100644
--- a/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java
+++ b/server/src/main/java/org/opensearch/cluster/node/DiscoveryNode.java
@@ -326,9 +326,14 @@ public DiscoveryNode(StreamInput in) throws IOException {
         this.address = new TransportAddress(in);
         int size = in.readVInt();
         this.attributes = new HashMap<>(size);
-        for (int i = 0; i < size; i++) {
-            this.attributes.put(in.readString(), in.readString());
+        if (in.getVersion().onOrAfter(Version.V_3_0_0) && !in.readBoolean()) {
+
+        } else {
+            for (int i = 0; i < size; i++) {
+                this.attributes.put(in.readString(), in.readString());
+            }
         }
+
         int rolesSize = in.readVInt();
         final Set<DiscoveryNodeRole> roles = new HashSet<>(rolesSize);
         for (int i = 0; i < rolesSize; i++) {
@@ -358,17 +363,38 @@ public DiscoveryNode(StreamInput in) throws IOException {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
+        writeToUtil(out, true);
+    }
+
+    public void writeToWithoutAttribute(StreamOutput out) throws IOException {
+        writeToUtil(out, false);
+    }
+
+    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());
+            if (out.getVersion().onOrAfter(Version.V_3_0_0)) {
+                out.writeBoolean(true);
+            }
+
+            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);
+            if (out.getVersion().onOrAfter(Version.V_3_0_0)) {
+                out.writeBoolean(false);
+            }
         }
+
         out.writeVInt(roles.size());
         for (final DiscoveryNodeRole role : roles) {
             final DiscoveryNodeRole compatibleRole = role.getCompatibilityRole(out.getVersion());