snapshot manager factory

Author: TimothyW553

kernel-spark/src/main/java/io/delta/kernel/spark/catalog/SparkTable.java

@@ -21,7 +21,7 @@
 import io.delta.kernel.Snapshot;
 import io.delta.kernel.spark.read.SparkScanBuilder;
 import io.delta.kernel.spark.snapshot.DeltaSnapshotManager;
-import io.delta.kernel.spark.snapshot.PathBasedSnapshotManager;
+import io.delta.kernel.spark.snapshot.SnapshotManagerFactory;
 import io.delta.kernel.spark.unity.UnityCatalogClientFactory;
 import io.delta.kernel.spark.utils.SchemaUtils;
 import java.util.*;
@@ -143,7 +143,9 @@ private SparkTable(
 
     this.hadoopConf =
         SparkSession.active().sessionState().newHadoopConfWithOptions(toScalaMap(options));
-    this.snapshotManager = new PathBasedSnapshotManager(tablePath, hadoopConf);
+    this.snapshotManager =
+        SnapshotManagerFactory.create(
+            identifier, tablePath, hadoopConf, this.catalogTable, this.unityCatalogClient);
     // Load the initial snapshot through the manager
     this.initialSnapshot = snapshotManager.loadLatestSnapshot();
     this.schema = SchemaUtils.convertKernelSchemaToSparkSchema(initialSnapshot.getSchema());

kernel-spark/src/main/java/io/delta/kernel/spark/snapshot/SnapshotManagerFactory.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright (2025) The Delta Lake Project Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.delta.kernel.spark.snapshot;
+
+import static java.util.Objects.requireNonNull;
+
+import io.delta.kernel.spark.unity.UnityCatalogClientFactory;
+import io.delta.kernel.spark.utils.CatalogTableUtils;
+import java.util.Optional;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.spark.sql.catalyst.catalog.CatalogTable;
+import org.apache.spark.sql.connector.catalog.Identifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Factory responsible for instantiating {@link DeltaSnapshotManager} implementations.
+ *
+ * <p>The factory centralises the decision of whether a table should use the traditional
+ * filesystem-based snapshot manager or a catalog-backed implementation. Today all tables rely on
+ * {@link PathBasedSnapshotManager}. Catalog-managed support will be integrated in a subsequent
+ * change once the corresponding snapshot manager is implemented.
+ */
+public final class SnapshotManagerFactory {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SnapshotManagerFactory.class);
+
+  private SnapshotManagerFactory() {}
+
+  /**
+   * Creates an appropriate {@link DeltaSnapshotManager} based on the provided metadata.
+   *
+   * @param identifier Spark identifier for the table being resolved
+   * @param tablePath canonical filesystem path to the table root
+   * @param hadoopConf Hadoop configuration pre-populated with user options
+   * @param catalogTable optional Spark {@link CatalogTable} descriptor when available
+   * @param unityCatalogClient optional Unity Catalog client handle for catalog-managed tables
+   * @return a snapshot manager implementation ready to serve table snapshots
+   */
+  public static DeltaSnapshotManager create(
+      Identifier identifier,
+      String tablePath,
+      Configuration hadoopConf,
+      Optional<CatalogTable> catalogTable,
+      Optional<UnityCatalogClientFactory.UnityCatalogClient> unityCatalogClient) {
+
+    requireNonNull(identifier, "identifier is null");
+    requireNonNull(tablePath, "tablePath is null");
+    requireNonNull(hadoopConf, "hadoopConf is null");
+    requireNonNull(catalogTable, "catalogTable optional is null");
+    requireNonNull(unityCatalogClient, "unityCatalogClient optional is null");
+
+    if (catalogTable.isPresent()
+        && CatalogTableUtils.isUnityCatalogManagedTable(catalogTable.get())
+        && unityCatalogClient.isPresent()) {
+      LOG.debug(
+          "Unity Catalog-managed table '{}' detected. Falling back to PathBasedSnapshotManager "
+              + "until catalog-managed support is wired.",
+          identifier);
+    }
+
+    return new PathBasedSnapshotManager(tablePath, hadoopConf);
+  }
+
+  /**
+   * Convenience overload for path-based tables without Spark catalog metadata.
+   *
+   * @param identifier Spark identifier for the table being resolved
+   * @param tablePath canonical filesystem path to the table root
+   * @param hadoopConf Hadoop configuration pre-populated with user options
+   * @return a {@link PathBasedSnapshotManager} instance
+   */
+  public static DeltaSnapshotManager createForPath(
+      Identifier identifier, String tablePath, Configuration hadoopConf) {
+    return create(identifier, tablePath, hadoopConf, Optional.empty(), Optional.empty());
+  }
+}