change service from interface to abstract class

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

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

@@ -6,12 +6,31 @@
 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 interface FlintMetadataLogService {
+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);
+  }
 
   /**
    * Start a new optimistic transaction.
@@ -20,15 +39,15 @@ public interface FlintMetadataLogService {
    * @param forceInit force init transaction and create empty metadata log if not exist
    * @return transaction handle
    */
-  <T> OptimisticTransaction<T> startTransaction(String indexName, boolean forceInit);
+  public abstract <T> OptimisticTransaction<T> startTransaction(String indexName, boolean forceInit);
 
   /**
    * Start a new optimistic transaction.
    *
    * @param indexName index name
    * @return transaction handle
    */
-  default <T> OptimisticTransaction<T> startTransaction(String indexName) {
+  public <T> OptimisticTransaction<T> startTransaction(String indexName) {
     return startTransaction(indexName, false);
   }
 
@@ -38,12 +57,12 @@ default <T> OptimisticTransaction<T> startTransaction(String indexName) {
    * @param indexName index name
    * @return optional metadata log
    */
-  Optional<FlintMetadataLog<FlintMetadataLogEntry>> getIndexMetadataLog(String indexName);
+  public abstract Optional<FlintMetadataLog<FlintMetadataLogEntry>> getIndexMetadataLog(String indexName);
 
   /**
    * Record heartbeat timestamp for index streaming job.
    *
    * @param indexName index name
    */
-  void recordHeartbeat(String indexName);
+  public abstract void recordHeartbeat(String indexName);
 }

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

@@ -8,6 +8,7 @@
 import java.io.IOException;
 import java.util.Optional;
 import java.util.logging.Logger;
+import org.apache.spark.SparkConf;
 import org.opensearch.client.RequestOptions;
 import org.opensearch.client.indices.CreateIndexRequest;
 import org.opensearch.client.indices.GetIndexRequest;
@@ -24,7 +25,7 @@
 /**
  * Flint metadata log service implementation for OpenSearch storage.
  */
-public class FlintOpenSearchMetadataLogService implements FlintMetadataLogService {
+public class FlintOpenSearchMetadataLogService extends FlintMetadataLogService {
 
   private static final Logger LOG = Logger.getLogger(FlintOpenSearchMetadataLogService.class.getName());