Added version check to MergedSegmentWarmer

Added changelog
Fixed tests

Signed-off-by: Aditya Khera <kheraadi@amazon.com>

Author: Aditya Khera

CHANGELOG.md

@@ -26,7 +26,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Wrap checked exceptions in painless.DefBootstrap to support JDK-25 ([#19706](https://github.com/opensearch-project/OpenSearch/pull/19706))
 - Refactor the ThreadPoolStats.Stats class to use the Builder pattern instead of constructors ([#19317](https://github.com/opensearch-project/OpenSearch/pull/19317))
 - Refactor the IndexingStats.Stats class to use the Builder pattern instead of constructors ([#19306](https://github.com/opensearch-project/OpenSearch/pull/19306))
-
+- Remove FeatureFlag.MERGED_SEGMENT_WARMER_EXPERIMENTAL_FLAG. ([#19715](https://github.com/opensearch-project/OpenSearch/pull/19715))
+-
 ### Fixed
 - Fix Allocation and Rebalance Constraints of WeightFunction are incorrectly reset ([#19012](https://github.com/opensearch-project/OpenSearch/pull/19012))
 - Fix flaky test FieldDataLoadingIT.testIndicesFieldDataCacheSizeSetting ([#19571](https://github.com/opensearch-project/OpenSearch/pull/19571))

server/src/main/java/org/opensearch/index/engine/MergedSegmentWarmer.java

@@ -14,6 +14,7 @@
 import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.SegmentCommitInfo;
 import org.apache.lucene.index.SegmentReader;
+import org.opensearch.Version;
 import org.opensearch.cluster.service.ClusterService;
 import org.opensearch.common.logging.Loggers;
 import org.opensearch.index.merge.MergedSegmentTransferTracker;
@@ -93,6 +94,12 @@ public void warm(LeafReader leafReader) throws IOException {
 
     // package-private for tests
     boolean shouldWarm() {
+        // Min node version check ensures that we only warm, when all nodes expect it
+        Version minNodeVersion = clusterService.state().nodes().getMinNodeVersion();
+        if (Version.V_3_4_0.compareTo(minNodeVersion) > 0) {
+            return false;
+        }
+
         return indexShard.getRecoverySettings().isMergedSegmentReplicationWarmerEnabled() == true;
     }
 }

server/src/test/java/org/opensearch/index/engine/MergedSegmentWarmerFactoryTests.java

@@ -54,7 +54,7 @@ public void tearDown() throws Exception {
         super.tearDown();
     }
 
-    public void testGetWithSegmentReplicationAndExperimentalFeatureFlagEnabled() {
+    public void testGetWithSegmentReplication() {
         IndexSettings indexSettings = createIndexSettings(
             false,
             Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.SEGMENT).build()
@@ -66,18 +66,7 @@ public void testGetWithSegmentReplicationAndExperimentalFeatureFlagEnabled() {
         assertTrue(warmer instanceof MergedSegmentWarmer);
     }
 
-    public void testGetWithSegmentReplicationAndExperimentalFeatureFlagDisabled() {
-        IndexSettings indexSettings = createIndexSettings(
-            false,
-            Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.SEGMENT).build()
-        );
-        when(indexShard.indexSettings()).thenReturn(indexSettings);
-        IndexWriter.IndexReaderWarmer warmer = factory.get(indexShard);
-
-        assertNull(warmer);
-    }
-
-    public void testGetWithRemoteStoreEnabledAndExperimentalFeatureFlagEnabled() {
+    public void testGetWithRemoteStoreEnabled() {
         IndexSettings indexSettings = createIndexSettings(
             true,
             Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.SEGMENT).build()
@@ -90,39 +79,14 @@ public void testGetWithRemoteStoreEnabledAndExperimentalFeatureFlagEnabled() {
         assertTrue(warmer instanceof MergedSegmentWarmer);
     }
 
-    public void testGetWithRemoteStoreEnabledAndExperimentalFeatureFlagDisabled() {
-        IndexSettings indexSettings = createIndexSettings(
-            true,
-            Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.SEGMENT).build()
-        );
-        when(indexShard.indexSettings()).thenReturn(indexSettings);
-
-        IndexWriter.IndexReaderWarmer warmer = factory.get(indexShard);
-
-        assertNull(warmer);
-    }
-
-    public void testGetWithDocumentReplicationAndExperimentalFeatureFlagEnabled() {
-        IndexSettings indexSettings = createIndexSettings(
-            false,
-            Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.DOCUMENT).build()
-        );
-
-        when(indexShard.indexSettings()).thenReturn(indexSettings);
-        IndexWriter.IndexReaderWarmer warmer = factory.get(indexShard);
-
-        assertNull(warmer);
-    }
-
-    public void testGetWithDocumentReplicationAndExperimentalFeatureFlagDisabled() {
+    public void testGetWithDocumentReplication() {
         IndexSettings indexSettings = createIndexSettings(
             false,
             Settings.builder().put(IndexMetadata.INDEX_REPLICATION_TYPE_SETTING.getKey(), ReplicationType.DOCUMENT).build()
         );
 
         when(indexShard.indexSettings()).thenReturn(indexSettings);
         IndexWriter.IndexReaderWarmer warmer = factory.get(indexShard);
-
         assertNull(warmer);
     }