[#7916] improvement(core): Using entity store's relation operation to refactor tag operation (#8700)

### What changes were proposed in this pull request?

Replace `SupportsTagOperations` with the entity store's relation
operations

### Why are the changes needed?

The entity store's relation operations are general enough, and there is
no need to create a new interface specifically for tags.

Fix: #7916

### Does this PR introduce _any_ user-facing change?

N/A

### How was this patch tested?

Existing UTs and ITs.

---------

Co-authored-by: Mini Yu <[email protected]>
Co-authored-by: Jerry Shao <[email protected]>

Author: 3 people

core/src/main/java/org/apache/gravitino/EntityStore.java

@@ -25,7 +25,6 @@
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.gravitino.Entity.EntityType;
 import org.apache.gravitino.exceptions.NoSuchEntityException;
-import org.apache.gravitino.tag.SupportsTagOperations;
 import org.apache.gravitino.utils.Executable;
 
 public interface EntityStore extends Closeable {
@@ -229,16 +228,6 @@ <E extends Entity & HasIdentifier> void batchPut(List<E> entities, boolean overw
   <R, E extends Exception> R executeInTransaction(Executable<R, E> executable)
       throws E, IOException;
 
-  /**
-   * Get the extra tag operations that are supported by the entity store.
-   *
-   * @return the tag operations object that are supported by the entity store
-   * @throws UnsupportedOperationException if the extra operations are not supported
-   */
-  default SupportsTagOperations tagOperations() {
-    throw new UnsupportedOperationException("tag operations are not supported");
-  }
-
   /**
    * Get the extra relation operations that are supported by the entity store.
    *

core/src/main/java/org/apache/gravitino/SupportsRelationOperations.java

@@ -39,7 +39,9 @@ enum Type {
     /** Role and group relationship */
     ROLE_GROUP_REL,
     /** Policy and metadata object relationship */
-    POLICY_METADATA_OBJECT_REL
+    POLICY_METADATA_OBJECT_REL,
+    /** Metadata object to tag relationship */
+    TAG_METADATA_OBJECT_REL,
   }
 
   /**
@@ -48,7 +50,7 @@ enum Type {
    * @param <E> The type of entities returned.
    * @param relType The type of relation.
    * @param nameIdentifier The given entity identifier.
-   * @param identType The given entity type.
+   * @param identType The entity type of parameter nameIdentifier represents.
    * @return The list of entities
    * @throws IOException When occurs storage issues, it will throw IOException.
    */
@@ -63,13 +65,28 @@ default <E extends Entity & HasIdentifier> List<E> listEntitiesByRelation(
    * @param <E> the type of entities returned.
    * @param relType The type of relation.
    * @param nameIdentifier The given entity identifier
-   * @param identType The given entity type.
+   * @param identType The entity type of parameter nameIdentifier represents.
    * @param allFields Some fields may have a relatively high acquisition cost, EntityStore provide
    *     an optional setting to avoid fetching these high-cost fields to improve the performance. If
    *     true, the method will fetch all the fields, Otherwise, the method will fetch all the fields
    *     except for high-cost fields.
    * @return The list of entities
    * @throws IOException When occurs storage issues, it will throw IOException.
+   *     <pre>
+   *  Let's see an example to illustrate how this method works.
+   *  If we want to list all the users who have a specific role, we can use this method as follows:
+   *
+   *    listEntitiesByRelation(ROLE_USER_REL, name_identifier_of_role, EntityType.ROLE);
+   *
+   *  This will return a list of User entities that are associated with the specified role.
+   *  Similarly, if we want to list all roles a user has, we can call:
+   *
+   *  listEntitiesByRelation(ROLE_USER_REL, name_identifier_of_user, EntityType.USER);
+   *
+   *  That is to say, this method is versatile and can be used to navigate relationships in both
+   *  directions, the start entity is determined by the identType and nameIdentifier parameters.
+   *  The end entity type is determined by the relType parameter and start entity.
+   * </pre>
    */
   <E extends Entity & HasIdentifier> List<E> listEntitiesByRelation(
       Type relType, NameIdentifier nameIdentifier, Entity.EntityType identType, boolean allFields)

core/src/main/java/org/apache/gravitino/storage/relational/JDBCBackend.java

@@ -36,7 +36,6 @@
 import org.apache.gravitino.Entity;
 import org.apache.gravitino.EntityAlreadyExistsException;
 import org.apache.gravitino.HasIdentifier;
-import org.apache.gravitino.MetadataObject;
 import org.apache.gravitino.NameIdentifier;
 import org.apache.gravitino.Namespace;
 import org.apache.gravitino.SupportsRelationOperations;
@@ -455,37 +454,6 @@ public void close() throws IOException {
     }
   }
 
-  @Override
-  public List<MetadataObject> listAssociatedMetadataObjectsForTag(NameIdentifier tagIdent)
-      throws IOException {
-    return TagMetaService.getInstance().listAssociatedMetadataObjectsForTag(tagIdent);
-  }
-
-  @Override
-  public List<TagEntity> listAssociatedTagsForMetadataObject(
-      NameIdentifier objectIdent, Entity.EntityType objectType)
-      throws NoSuchEntityException, IOException {
-    return TagMetaService.getInstance().listTagsForMetadataObject(objectIdent, objectType);
-  }
-
-  @Override
-  public TagEntity getTagForMetadataObject(
-      NameIdentifier objectIdent, Entity.EntityType objectType, NameIdentifier tagIdent)
-      throws NoSuchEntityException, IOException {
-    return TagMetaService.getInstance().getTagForMetadataObject(objectIdent, objectType, tagIdent);
-  }
-
-  @Override
-  public List<TagEntity> associateTagsWithMetadataObject(
-      NameIdentifier objectIdent,
-      Entity.EntityType objectType,
-      NameIdentifier[] tagsToAdd,
-      NameIdentifier[] tagsToRemove)
-      throws NoSuchEntityException, EntityAlreadyExistsException, IOException {
-    return TagMetaService.getInstance()
-        .associateTagsWithMetadataObject(objectIdent, objectType, tagsToAdd, tagsToRemove);
-  }
-
   @Override
   public int batchDelete(
       List<Pair<NameIdentifier, Entity.EntityType>> entitiesToDelete, boolean cascade)
@@ -597,6 +565,15 @@ public <E extends Entity & HasIdentifier> List<E> listEntitiesByRelation(
               PolicyMetaService.getInstance()
                   .listPoliciesForMetadataObject(nameIdentifier, identType);
         }
+
+      case TAG_METADATA_OBJECT_REL:
+        if (identType == Entity.EntityType.TAG) {
+          return (List<E>)
+              TagMetaService.getInstance().listAssociatedMetadataObjectsForTag(nameIdentifier);
+        } else {
+          return (List<E>)
+              TagMetaService.getInstance().listTagsForMetadataObject(nameIdentifier, identType);
+        }
       default:
         throw new IllegalArgumentException(
             String.format("Doesn't support the relation type %s", relType));
@@ -635,6 +612,11 @@ public <E extends Entity & HasIdentifier> List<E> updateEntityRelations(
             PolicyMetaService.getInstance()
                 .associatePoliciesWithMetadataObject(
                     srcEntityIdent, srcEntityType, destEntitiesToAdd, destEntitiesToRemove);
+      case TAG_METADATA_OBJECT_REL:
+        return (List<E>)
+            TagMetaService.getInstance()
+                .associateTagsWithMetadataObject(
+                    srcEntityIdent, srcEntityType, destEntitiesToAdd, destEntitiesToRemove);
       default:
         throw new IllegalArgumentException(
             String.format("Doesn't support the relation type %s", relType));
@@ -653,6 +635,10 @@ public <E extends Entity & HasIdentifier> E getEntityByRelation(
         return (E)
             PolicyMetaService.getInstance()
                 .getPolicyForMetadataObject(srcIdentifier, srcType, destEntityIdent);
+      case TAG_METADATA_OBJECT_REL:
+        return (E)
+            TagMetaService.getInstance()
+                .getTagForMetadataObject(srcIdentifier, srcType, destEntityIdent);
       default:
         throw new IllegalArgumentException(
             String.format("Doesn't support the relation type %s", relType));

core/src/main/java/org/apache/gravitino/storage/relational/RelationalBackend.java

@@ -31,11 +31,9 @@
 import org.apache.gravitino.Namespace;
 import org.apache.gravitino.SupportsRelationOperations;
 import org.apache.gravitino.exceptions.NoSuchEntityException;
-import org.apache.gravitino.tag.SupportsTagOperations;
 
 /** Interface defining the operations for a Relation Backend. */
-public interface RelationalBackend
-    extends Closeable, SupportsTagOperations, SupportsRelationOperations {
+public interface RelationalBackend extends Closeable, SupportsRelationOperations {
 
   /**
    * Initializes the Relational Backend environment with the provided configuration.

core/src/main/java/org/apache/gravitino/storage/relational/RelationalEntityStore.java

@@ -32,7 +32,6 @@
 import org.apache.gravitino.EntityAlreadyExistsException;
 import org.apache.gravitino.EntityStore;
 import org.apache.gravitino.HasIdentifier;
-import org.apache.gravitino.MetadataObject;
 import org.apache.gravitino.NameIdentifier;
 import org.apache.gravitino.Namespace;
 import org.apache.gravitino.SupportsRelationOperations;
@@ -41,8 +40,6 @@
 import org.apache.gravitino.cache.EntityCacheRelationKey;
 import org.apache.gravitino.cache.NoOpsCache;
 import org.apache.gravitino.exceptions.NoSuchEntityException;
-import org.apache.gravitino.meta.TagEntity;
-import org.apache.gravitino.tag.SupportsTagOperations;
 import org.apache.gravitino.utils.Executable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -52,8 +49,7 @@
  * MySQL, PostgreSQL, etc. If you want to use a different backend, you can implement the {@link
  * RelationalBackend} interface
  */
-public class RelationalEntityStore
-    implements EntityStore, SupportsTagOperations, SupportsRelationOperations {
+public class RelationalEntityStore implements EntityStore, SupportsRelationOperations {
   private static final Logger LOGGER = LoggerFactory.getLogger(RelationalEntityStore.class);
   public static final ImmutableMap<String, String> RELATIONAL_BACKENDS =
       ImmutableMap.of(
@@ -166,47 +162,11 @@ public void close() throws IOException {
     backend.close();
   }
 
-  @Override
-  public SupportsTagOperations tagOperations() {
-    return this;
-  }
-
   @Override
   public SupportsRelationOperations relationOperations() {
     return this;
   }
 
-  @Override
-  public List<MetadataObject> listAssociatedMetadataObjectsForTag(NameIdentifier tagIdent)
-      throws IOException {
-    return backend.listAssociatedMetadataObjectsForTag(tagIdent);
-  }
-
-  @Override
-  public List<TagEntity> listAssociatedTagsForMetadataObject(
-      NameIdentifier objectIdent, Entity.EntityType objectType)
-      throws NoSuchEntityException, IOException {
-    return backend.listAssociatedTagsForMetadataObject(objectIdent, objectType);
-  }
-
-  @Override
-  public TagEntity getTagForMetadataObject(
-      NameIdentifier objectIdent, Entity.EntityType objectType, NameIdentifier tagIdent)
-      throws NoSuchEntityException, IOException {
-    return backend.getTagForMetadataObject(objectIdent, objectType, tagIdent);
-  }
-
-  @Override
-  public List<TagEntity> associateTagsWithMetadataObject(
-      NameIdentifier objectIdent,
-      Entity.EntityType objectType,
-      NameIdentifier[] tagsToAdd,
-      NameIdentifier[] tagsToRemove)
-      throws NoSuchEntityException, EntityAlreadyExistsException, IOException {
-    return backend.associateTagsWithMetadataObject(
-        objectIdent, objectType, tagsToAdd, tagsToRemove);
-  }
-
   @Override
   public <E extends Entity & HasIdentifier> List<E> listEntitiesByRelation(
       Type relType, NameIdentifier nameIdentifier, Entity.EntityType identType, boolean allFields)

core/src/main/java/org/apache/gravitino/storage/relational/service/TagMetaService.java

@@ -32,11 +32,11 @@
 import org.apache.gravitino.EntityAlreadyExistsException;
 import org.apache.gravitino.HasIdentifier;
 import org.apache.gravitino.MetadataObject;
-import org.apache.gravitino.MetadataObjects;
 import org.apache.gravitino.NameIdentifier;
 import org.apache.gravitino.Namespace;
 import org.apache.gravitino.exceptions.NoSuchEntityException;
 import org.apache.gravitino.exceptions.NoSuchTagException;
+import org.apache.gravitino.meta.GenericEntity;
 import org.apache.gravitino.meta.TagEntity;
 import org.apache.gravitino.storage.relational.mapper.TagMetaMapper;
 import org.apache.gravitino.storage.relational.mapper.TagMetadataObjectRelMapper;
@@ -218,7 +218,7 @@ public TagEntity getTagForMetadataObject(
     return POConverters.fromTagPO(tagPO, NamespaceUtil.ofTag(metalake));
   }
 
-  public List<MetadataObject> listAssociatedMetadataObjectsForTag(NameIdentifier tagIdent)
+  public List<GenericEntity> listAssociatedMetadataObjectsForTag(NameIdentifier tagIdent)
       throws IOException {
     String metalakeName = tagIdent.namespace().level(0);
     String tagName = tagIdent.name();
@@ -230,7 +230,7 @@ public List<MetadataObject> listAssociatedMetadataObjectsForTag(NameIdentifier t
               mapper ->
                   mapper.listTagMetadataObjectRelsByMetalakeAndTagName(metalakeName, tagName));
 
-      List<MetadataObject> metadataObjects = Lists.newArrayList();
+      List<GenericEntity> metadataObjects = Lists.newArrayList();
       Map<String, List<TagMetadataObjectRelPO>> tagMetadataObjectRelPOsByType =
           tagMetadataObjectRelPOs.stream()
               .collect(Collectors.groupingBy(TagMetadataObjectRelPO::getMetadataObjectType));
@@ -256,7 +256,11 @@ public List<MetadataObject> listAssociatedMetadataObjectsForTag(NameIdentifier t
           // return null, we should skip this metadata object.
           if (fullName != null) {
             metadataObjects.add(
-                MetadataObjects.parse(fullName, MetadataObject.Type.valueOf(metadataObjectType)));
+                GenericEntity.builder()
+                    .withName(fullName)
+                    .withEntityType(Entity.EntityType.valueOf(metadataObjectType))
+                    .withId(metadataObjectName.getKey())
+                    .build());
           }
         }
       }