content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.security.group;
  
  import alluxio.annotation.PublicApi;
  import alluxio.conf.AlluxioConfiguration;
  import alluxio.conf.PropertyKey;
  import alluxio.util.CommonUtils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.util.List;
  
  /**
   * Interface for Alluxio user-to-groups mapping. {@link GroupMappingService} allows for server to
   * get the various group memberships of a given user via the {@link #getGroups(String)} call, thus
   * ensuring a consistent user-to-groups mapping and protects against mapping inconsistencies between
   * servers and clients in an Alluxio cluster.
   */
  @PublicApi
  public interface GroupMappingService {
  
    /**
     * Factory for creating a new instance.
     */
    class Factory {
      private static final Logger LOG = LoggerFactory.getLogger(GroupMappingService.Factory.class);
  
      // TODO(chaomin): maintain a map from SECURITY_GROUP_MAPPING_CLASS name to cachedGroupMapping.
      // Currently the single global cached GroupMappingService assumes that there is no dynamic
      // configuration change for {@link Constants#SECURITY_GROUP_MAPPING_CLASS}.
      private static volatile CachedGroupMapping sCachedGroupMapping = null;
  
      // prevent instantiation
      private Factory() {
      }
  
      /**
       * Gets the cached groups mapping service being used to map user-to-groups.
       *
       * @return the groups mapping service being used to map user-to-groups
       */
      public static GroupMappingService get(AlluxioConfiguration conf) {
        if (sCachedGroupMapping == null) {
          synchronized (Factory.class) {
            if (sCachedGroupMapping == null) {
              LOG.debug("Creating new Groups object");
              GroupMappingService groupMappingService =
                  CommonUtils.createNewClassInstance(conf.<GroupMappingService>getClass(
                      PropertyKey.SECURITY_GROUP_MAPPING_CLASS), null, null);
              sCachedGroupMapping = new CachedGroupMapping(groupMappingService,
                  conf.getMs(PropertyKey.SECURITY_GROUP_MAPPING_CACHE_TIMEOUT_MS));
            }
          }
        }
        return sCachedGroupMapping;
      }
    }
  
    /**
     * Gets all various group memberships of a given user. Returns EMPTY list in case of non-existing
     * user.
     *
     * @param user user's name
     * @return group memberships of user
     */
    List<String> getGroups(String user) throws IOException;
  }
  