Add toBuilder() method in EngineConfig (opensearch-project#19054)

* Add a toBuilder() method

Signed-off-by: Rajat Gupta <gptrajat@amazon.com>

* Fix release version

Signed-off-by: Rajat Gupta <gptrajat@amazon.com>

---------

Signed-off-by: Rajat Gupta <gptrajat@amazon.com>
Signed-off-by: Craig Perkins <cwperx@amazon.com>
Co-authored-by: Rajat Gupta <gptrajat@amazon.com>
Co-authored-by: Craig Perkins <cwperx@amazon.com>

Author: 3 people

CHANGELOG.md

@@ -8,7 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Expand fetch phase profiling to support inner hits and top hits aggregation phases  ([##18936](https://github.com/opensearch-project/OpenSearch/pull/18936))
 - Add temporal routing processors for time-based document routing ([#18920](https://github.com/opensearch-project/OpenSearch/issues/18920))
 - The dynamic mapping parameter supports false_allow_templates ([#19065](https://github.com/opensearch-project/OpenSearch/pull/19065))
-
+- Add a toBuilder method in EngineConfig to support easy modification of configs([#19054](https://github.com/opensearch-project/OpenSearch/pull/19054))
 
 ### Changed
 - Add CompletionStage variants to methods in the Client Interface and default to ActionListener impl ([#18998](https://github.com/opensearch-project/OpenSearch/pull/18998))

server/src/main/java/org/opensearch/index/codec/CodecService.java

@@ -37,6 +37,7 @@
 import org.apache.lucene.codecs.lucene101.Lucene101Codec;
 import org.apache.lucene.codecs.lucene101.Lucene101Codec.Mode;
 import org.opensearch.common.Nullable;
+import org.opensearch.common.annotation.PublicApi;
 import org.opensearch.common.collect.MapBuilder;
 import org.opensearch.index.IndexSettings;
 import org.opensearch.index.codec.composite.CompositeCodecFactory;
@@ -50,8 +51,9 @@
  * data-structures per field. OpenSearch exposes the full
  * {@link Codec} capabilities through this {@link CodecService}.
  *
- * @opensearch.internal
+ * @opensearch.api
  */
+@PublicApi(since = "3.3.0")
 public class CodecService {
 
     private final Map<String, Codec> codecs;

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

@@ -317,6 +317,45 @@ public void setEnableGcDeletes(boolean enableGcDeletes) {
         this.enableGcDeletes = enableGcDeletes;
     }
 
+    /**
+     * Creates a new Builder pre-populated with all values from this EngineConfig.
+     * This allows for easy modification of specific fields while preserving all others.
+     *
+     * @return a new Builder instance with all current configuration values
+     */
+    public Builder toBuilder() {
+        return new Builder().shardId(this.shardId)
+            .threadPool(this.threadPool)
+            .indexSettings(this.indexSettings)
+            .warmer(this.warmer)
+            .store(this.store)
+            .mergePolicy(this.mergePolicy)
+            .analyzer(this.analyzer)
+            .similarity(this.similarity)
+            .codecService(this.codecService)
+            .eventListener(this.eventListener)
+            .queryCache(this.queryCache)
+            .queryCachingPolicy(this.queryCachingPolicy)
+            .translogConfig(this.translogConfig)
+            .translogDeletionPolicyFactory(this.translogDeletionPolicyFactory)
+            .flushMergesAfter(this.flushMergesAfter)
+            .externalRefreshListener(this.externalRefreshListener)
+            .internalRefreshListener(this.internalRefreshListener)
+            .indexSort(this.indexSort)
+            .circuitBreakerService(this.circuitBreakerService)
+            .globalCheckpointSupplier(this.globalCheckpointSupplier)
+            .retentionLeasesSupplier(this.retentionLeasesSupplier)
+            .primaryTermSupplier(this.primaryTermSupplier)
+            .tombstoneDocSupplier(this.tombstoneDocSupplier)
+            .readOnlyReplica(this.isReadOnlyReplica)
+            .startedPrimarySupplier(this.startedPrimarySupplier)
+            .translogFactory(this.translogFactory)
+            .leafSorter(this.leafSorter)
+            .documentMapperForTypeSupplier(this.documentMapperForTypeSupplier)
+            .indexReaderWarmer(this.indexReaderWarmer)
+            .clusterApplierService(this.clusterApplierService);
+    }
+
     /**
      * Returns the initial index buffer size. This setting is only read on startup and otherwise controlled
      * by {@link IndexingMemoryController}
@@ -589,8 +628,9 @@ public ClusterApplierService getClusterApplierService() {
     /**
      * Builder for EngineConfig class
      *
-     * @opensearch.internal
+     * @opensearch.api
      */
+    @PublicApi(since = "3.3.0")
     public static class Builder {
         private ShardId shardId;
         private ThreadPool threadPool;