Revert "change service to abstract class"

This reverts commit 95b7a9d.

Signed-off-by: Sean Kao <[email protected]>

flint-commons/src/main/scala/org/opensearch/flint/common/metadata/log/FlintMetadataLogService.java

@@ -6,31 +6,12 @@
 package org.opensearch.flint.common.metadata.log;
 
 import java.util.Optional;
-import org.apache.spark.SparkConf;
 
 /**
  * Flint metadata log service provides API for metadata log related operations on a Flint index
  * regardless of underlying storage.
  */
-public abstract class FlintMetadataLogService {
-
-  protected final SparkConf sparkConf;
-
-  /**
-   * Constructor.
-   *
-   * @param sparkConf spark configuration
-   */
-  public FlintMetadataLogService(SparkConf sparkConf) {
-    this.sparkConf = sparkConf;
-  }
-
-  /**
-   * Default constructor.
-   */
-  public FlintMetadataLogService() {
-    this(null);
-  }
+public interface FlintMetadataLogService {
 
   /**
    * Start a new optimistic transaction.
@@ -39,15 +20,15 @@ public FlintMetadataLogService() {
    * @param forceInit force init transaction and create empty metadata log if not exist
    * @return transaction handle
    */
-  public abstract <T> OptimisticTransaction<T> startTransaction(String indexName, boolean forceInit);
+  <T> OptimisticTransaction<T> startTransaction(String indexName, boolean forceInit);
 
   /**
    * Start a new optimistic transaction.
    *
    * @param indexName index name
    * @return transaction handle
    */
-  public <T> OptimisticTransaction<T> startTransaction(String indexName) {
+  default <T> OptimisticTransaction<T> startTransaction(String indexName) {
     return startTransaction(indexName, false);
   }
 
@@ -57,12 +38,12 @@ public <T> OptimisticTransaction<T> startTransaction(String indexName) {
    * @param indexName index name
    * @return optional metadata log
    */
-  public abstract Optional<FlintMetadataLog<FlintMetadataLogEntry>> getIndexMetadataLog(String indexName);
+  Optional<FlintMetadataLog<FlintMetadataLogEntry>> getIndexMetadataLog(String indexName);
 
   /**
    * Record heartbeat timestamp for index streaming job.
    *
    * @param indexName index name
    */
-  public abstract void recordHeartbeat(String indexName);
+  void recordHeartbeat(String indexName);
 }

flint-core/src/main/scala/org/opensearch/flint/core/storage/FlintOpenSearchMetadataLogService.java

@@ -24,7 +24,7 @@
 /**
  * Flint metadata log service implementation for OpenSearch storage.
  */
-public class FlintOpenSearchMetadataLogService extends FlintMetadataLogService {
+public class FlintOpenSearchMetadataLogService implements FlintMetadataLogService {
 
   private static final Logger LOG = Logger.getLogger(FlintOpenSearchMetadataLogService.class.getName());
 

integ-test/src/test/scala/org/opensearch/flint/core/FlintMetadataLogITSuite.scala

@@ -119,8 +119,7 @@ class FlintMetadataLogITSuite extends OpenSearchTransactionSuite with Matchers {
   }
 }
 
-case class TestMetadataLogService(sparkConfParam: SparkConf)
-    extends FlintMetadataLogService(sparkConfParam) {
+case class TestMetadataLogService(sparkConf: SparkConf) extends FlintMetadataLogService {
   override def startTransaction[T](
       indexName: String,
       forceInit: Boolean): OptimisticTransaction[T] = {