Add ListRoles

clients/client-java/src/main/java/org/apache/gravitino/client/GravitinoClient.java

@@ -168,6 +168,28 @@ public User getUser(String user) throws NoSuchUserException, NoSuchMetalakeExcep
     return getMetalake().getUser(user);
   }
 
+  /**
+   * Lists the users.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The User list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  public User[] listUsers(String metalake) {
+    return getMetalake().listUsers(metalake);
+  }
+
+  /**
+   * Lists the usernames.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The username list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  public String[] listUserNames(String metalake) {
+    return getMetalake().listUserNames(metalake);
+  }
+
   /**
    * Adds a new Group.
    *

clients/client-java/src/main/java/org/apache/gravitino/client/GravitinoMetalake.java

@@ -68,6 +68,7 @@
 import org.apache.gravitino.dto.responses.SetResponse;
 import org.apache.gravitino.dto.responses.TagListResponse;
 import org.apache.gravitino.dto.responses.TagResponse;
+import org.apache.gravitino.dto.responses.UserListResponse;
 import org.apache.gravitino.dto.responses.UserResponse;
 import org.apache.gravitino.exceptions.CatalogAlreadyExistsException;
 import org.apache.gravitino.exceptions.GroupAlreadyExistsException;
@@ -515,6 +516,48 @@ public User getUser(String user) throws NoSuchUserException, NoSuchMetalakeExcep
     return resp.getUser();
   }
 
+  /**
+   * Lists the users.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The User list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  public User[] listUsers(String metalake) throws NoSuchMetalakeException {
+    Map<String, String> params = new HashMap<>();
+    params.put("details", "true");
+
+    UserListResponse resp =
+        restClient.get(
+            String.format(API_METALAKES_USERS_PATH, metalake, BLANK_PLACE_HOLDER),
+            params,
+            UserListResponse.class,
+            Collections.emptyMap(),
+            ErrorHandlers.userErrorHandler());
+    resp.validate();
+
+    return resp.getUsers();
+  }
+
+  /**
+   * Lists the usernames.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The username list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  public String[] listUserNames(String metalake) throws NoSuchMetalakeException {
+    NameListResponse resp =
+        restClient.get(
+            String.format(API_METALAKES_USERS_PATH, metalake, BLANK_PLACE_HOLDER),
+            NameListResponse.class,
+            Collections.emptyMap(),
+            ErrorHandlers.userErrorHandler());
+    resp.validate();
+
+    return resp.getNames();
+  }
+
   /**
    * Adds a new Group.
    *

clients/client-java/src/test/java/org/apache/gravitino/client/TestUserGroup.java

@@ -24,6 +24,8 @@
 import static org.apache.hc.core5.http.HttpStatus.SC_SERVER_ERROR;
 
 import java.time.Instant;
+import java.util.Collections;
+import java.util.Map;
 import org.apache.gravitino.authorization.Group;
 import org.apache.gravitino.authorization.User;
 import org.apache.gravitino.dto.AuditDTO;
@@ -35,7 +37,9 @@
 import org.apache.gravitino.dto.responses.ErrorResponse;
 import org.apache.gravitino.dto.responses.GroupResponse;
 import org.apache.gravitino.dto.responses.MetalakeResponse;
+import org.apache.gravitino.dto.responses.NameListResponse;
 import org.apache.gravitino.dto.responses.RemoveResponse;
+import org.apache.gravitino.dto.responses.UserListResponse;
 import org.apache.gravitino.dto.responses.UserResponse;
 import org.apache.gravitino.exceptions.GroupAlreadyExistsException;
 import org.apache.gravitino.exceptions.NoSuchGroupException;
@@ -175,6 +179,59 @@ public void testRemoveUsers() throws Exception {
     Assertions.assertThrows(RuntimeException.class, () -> gravitinoClient.removeUser(username));
   }
 
+  @Test
+  public void testListUserNames() throws Exception {
+    String userPath = withSlash(String.format(API_METALAKES_USERS_PATH, metalakeName, ""));
+
+    NameListResponse listResponse = new NameListResponse(new String[] {"user1", "user2"});
+    buildMockResource(Method.GET, userPath, null, listResponse, SC_OK);
+
+    Assertions.assertArrayEquals(
+        new String[] {"user1", "user2"}, gravitinoClient.listUserNames(metalakeName));
+
+    ErrorResponse errRespNoMetalake =
+        ErrorResponse.notFound(NoSuchMetalakeException.class.getSimpleName(), "metalake not found");
+    buildMockResource(Method.GET, userPath, null, errRespNoMetalake, SC_NOT_FOUND);
+    Exception ex =
+        Assertions.assertThrows(
+            NoSuchMetalakeException.class, () -> gravitinoClient.listUserNames(metalakeName));
+    Assertions.assertEquals("metalake not found", ex.getMessage());
+
+    // Test RuntimeException
+    ErrorResponse errResp = ErrorResponse.internalError("internal error");
+    buildMockResource(Method.GET, userPath, null, errResp, SC_SERVER_ERROR);
+    Assertions.assertThrows(
+        RuntimeException.class, () -> gravitinoClient.listUserNames(metalakeName));
+  }
+
+  @Test
+  public void testListUsers() throws Exception {
+    String userPath = withSlash(String.format(API_METALAKES_USERS_PATH, metalakeName, ""));
+    UserDTO user1 = mockUserDTO("user1");
+    UserDTO user2 = mockUserDTO("user2");
+    Map<String, String> params = Collections.singletonMap("details", "true");
+    UserListResponse listResponse = new UserListResponse(new UserDTO[] {user1, user2});
+    buildMockResource(Method.GET, userPath, params, null, listResponse, SC_OK);
+
+    User[] users = gravitinoClient.listUsers(metalakeName);
+    Assertions.assertEquals(2, users.length);
+    assertUser(user1, users[0]);
+    assertUser(user2, users[1]);
+
+    ErrorResponse errRespNoMetalake =
+        ErrorResponse.notFound(NoSuchMetalakeException.class.getSimpleName(), "metalake not found");
+    buildMockResource(Method.GET, userPath, params, null, errRespNoMetalake, SC_NOT_FOUND);
+    Exception ex =
+        Assertions.assertThrows(
+            NoSuchMetalakeException.class, () -> gravitinoClient.listUsers(metalakeName));
+    Assertions.assertEquals("metalake not found", ex.getMessage());
+
+    // Test RuntimeException
+    ErrorResponse errResp = ErrorResponse.internalError("internal error");
+    buildMockResource(Method.GET, userPath, params, null, errResp, SC_SERVER_ERROR);
+    Assertions.assertThrows(RuntimeException.class, () -> gravitinoClient.listUsers(metalakeName));
+  }
+
   @Test
   public void testAddGroups() throws Exception {
     String groupName = "group";

common/src/main/java/org/apache/gravitino/dto/responses/UserListResponse.java

@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.gravitino.dto.responses;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.base.Preconditions;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.ToString;
+import org.apache.gravitino.dto.authorization.UserDTO;
+
+/** Represents a response containing a list of users. */
+@Getter
+@ToString
+@EqualsAndHashCode(callSuper = true)
+public class UserListResponse extends BaseResponse {
+
+  @JsonProperty("users")
+  private final UserDTO[] users;
+
+  /**
+   * Constructor for UserListResponse.
+   *
+   * @param users The array of users.
+   */
+  public UserListResponse(UserDTO[] users) {
+    super(0);
+    this.users = users;
+  }
+
+  /**
+   * This is the constructor that is used by Jackson deserializer to create an instance of
+   * UserListResponse.
+   */
+  public UserListResponse() {
+    super(0);
+    this.users = null;
+  }
+
+  /**
+   * Validates the response data.
+   *
+   * @throws IllegalArgumentException if users are not set.
+   */
+  @Override
+  public void validate() throws IllegalArgumentException {
+    super.validate();
+    Preconditions.checkArgument(users != null, "users must not be null");
+  }
+}

common/src/main/java/org/apache/gravitino/dto/util/DTOConverters.java

@@ -678,6 +678,19 @@ public static CatalogDTO[] toDTOs(Catalog[] catalogs) {
     return Arrays.stream(catalogs).map(DTOConverters::toDTO).toArray(CatalogDTO[]::new);
   }
 
+  /**
+   * Converts an array of Users to an array of UserDTOs.
+   *
+   * @param users The users to be converted.
+   * @return The array of UserDTOs.
+   */
+  public static UserDTO[] toDTOs(User[] users) {
+    if (ArrayUtils.isEmpty(users)) {
+      return new UserDTO[0];
+    }
+    return Arrays.stream(users).map(DTOConverters::toDTO).toArray(UserDTO[]::new);
+  }
+
   /**
    * Converts a DistributionDTO to a Distribution.
    *

core/src/main/java/org/apache/gravitino/authorization/AccessControlDispatcher.java

@@ -71,6 +71,24 @@ User addUser(String metalake, String user)
    */
   User getUser(String metalake, String user) throws NoSuchUserException, NoSuchMetalakeException;
 
+  /**
+   * Lists the users.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The User list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  User[] listUsers(String metalake) throws NoSuchMetalakeException;
+
+  /**
+   * Lists the usernames.
+   *
+   * @param metalake The Metalake of the User.
+   * @return The username list.
+   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
+   */
+  String[] listUserNames(String metalake) throws NoSuchMetalakeException;
+
   /**
    * Adds a new Group.
    *

core/src/main/java/org/apache/gravitino/authorization/AccessControlManager.java

@@ -69,6 +69,15 @@ public User getUser(String metalake, String user)
   }
 
   @Override
+  public String[] listUserNames(String metalake) throws NoSuchMetalakeException {
+    return userGroupManager.listUserNames(metalake);
+  }
+
+  @Override
+  public User[] listUsers(String metalake) throws NoSuchMetalakeException {
+    return userGroupManager.listUsers(metalake);
+  }
+
   public Group addGroup(String metalake, String group)
       throws GroupAlreadyExistsException, NoSuchMetalakeException {
     return userGroupManager.addGroup(metalake, group);
@@ -130,16 +139,6 @@ public Role getRole(String metalake, String role)
     return roleManager.getRole(metalake, role);
   }
 
-  /**
-   * Deletes a Role.
-   *
-   * @param metalake The Metalake of the Role.
-   * @param role The name of the Role.
-   * @return True if the Role was successfully deleted, false only when there's no such role,
-   *     otherwise it will throw an exception.
-   * @throws NoSuchMetalakeException If the Metalake with the given name does not exist.
-   * @throws RuntimeException If deleting the Role encounters storage issues.
-   */
   public boolean deleteRole(String metalake, String role) throws NoSuchMetalakeException {
     return roleManager.deleteRole(metalake, role);
   }

core/src/main/java/org/apache/gravitino/authorization/UserGroupManager.java

@@ -21,13 +21,16 @@
 import com.google.common.collect.Lists;
 import java.io.IOException;
 import java.time.Instant;
+import java.util.Arrays;
 import java.util.Collections;
 import org.apache.gravitino.Entity;
 import org.apache.gravitino.EntityAlreadyExistsException;
 import org.apache.gravitino.EntityStore;
+import org.apache.gravitino.Namespace;
 import org.apache.gravitino.exceptions.GroupAlreadyExistsException;
 import org.apache.gravitino.exceptions.NoSuchEntityException;
 import org.apache.gravitino.exceptions.NoSuchGroupException;
+import org.apache.gravitino.exceptions.NoSuchMetalakeException;
 import org.apache.gravitino.exceptions.NoSuchUserException;
 import org.apache.gravitino.exceptions.UserAlreadyExistsException;
 import org.apache.gravitino.meta.AuditInfo;
@@ -46,6 +49,7 @@
 class UserGroupManager {
 
   private static final Logger LOG = LoggerFactory.getLogger(UserGroupManager.class);
+  private static final String METALAKE_DOES_NOT_EXIST_MSG = "Metalake %s does not exist";
 
   private final EntityStore store;
   private final IdGenerator idGenerator;
@@ -109,6 +113,25 @@ User getUser(String metalake, String user) throws NoSuchUserException {
     }
   }
 
+  String[] listUserNames(String metalake) {
+    return Arrays.stream(listUsers(metalake)).map(User::name).toArray(String[]::new);
+  }
+
+  User[] listUsers(String metalake) {
+    try {
+      Namespace namespace = AuthorizationUtils.ofUserNamespace(metalake);
+      return store.list(namespace, UserEntity.class, Entity.EntityType.USER).stream()
+          .map(entity -> (User) entity)
+          .toArray(User[]::new);
+    } catch (NoSuchEntityException e) {
+      LOG.warn("Metalake {} does not exist", metalake, e);
+      throw new NoSuchMetalakeException(METALAKE_DOES_NOT_EXIST_MSG, metalake);
+    } catch (IOException ioe) {
+      LOG.error("Listing user under metalake {} failed due to storage issues", metalake, ioe);
+      throw new RuntimeException(ioe);
+    }
+  }
+
   Group addGroup(String metalake, String group) throws GroupAlreadyExistsException {
     try {
       AuthorizationUtils.checkMetalakeExists(metalake);

core/src/main/java/org/apache/gravitino/hook/AccessControlHookDispatcher.java

@@ -69,6 +69,16 @@ public User getUser(String metalake, String user)
     return dispatcher.getUser(metalake, user);
   }
 
+  @Override
+  public User[] listUsers(String metalake) throws NoSuchMetalakeException {
+    return dispatcher.listUsers(metalake);
+  }
+
+  @Override
+  public String[] listUserNames(String metalake) throws NoSuchMetalakeException {
+    return dispatcher.listUserNames(metalake);
+  }
+
   @Override
   public Group addGroup(String metalake, String group)
       throws GroupAlreadyExistsException, NoSuchMetalakeException {

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

@@ -104,6 +104,8 @@ public <E extends Entity & HasIdentifier> List<E> list(
         return (List<E>) TopicMetaService.getInstance().listTopicsByNamespace(namespace);
       case TAG:
         return (List<E>) TagMetaService.getInstance().listTagsByNamespace(namespace);
+      case USER:
+        return (List<E>) UserMetaService.getInstance().listUsersByNamespace(namespace);
       default:
         throw new UnsupportedEntityTypeException(
             "Unsupported entity type: %s for list operation", entityType);