001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.runtime.common.client.defaults;
020
021import org.apache.reef.annotations.audience.ClientSide;
022import org.apache.reef.annotations.audience.DriverSide;
023import org.apache.reef.annotations.audience.Private;
024import org.apache.reef.runtime.common.UserCredentials;
025
026import javax.inject.Inject;
027import java.io.IOException;
028import java.security.PrivilegedExceptionAction;
029
030/**
031 * A holder object for REEF user credentials.
032 */
033@Private
034@ClientSide
035@DriverSide
036public final class DefaultUserCredentials implements UserCredentials {
037
038  @Inject
039  private DefaultUserCredentials() { }
040
041  /**
042   * Copy credentials from another existing user.
043   * This method can be called only once per instance.
044   * This default implementation should never be called.
045   * @param name Name of the new user.
046   * @param other Credentials of another user.
047   * @throws RuntimeException always throws.
048   */
049  @Override
050  public void set(final String name, final UserCredentials other) throws IOException {
051    throw new RuntimeException("Not implemented! Attempt to set user " + name + " from: " + other);
052  }
053
054  /**
055   * Check if the user credentials had been set. Always returns false.
056   * @return always false.
057   */
058  @Override
059  public boolean isSet() {
060    return false;
061  }
062
063  /**
064   * Execute the privileged action as a given user.
065   * This implementation always executes the action outside the user context, simply by calling action.run().
066   * @param action an action to run.
067   * @param <T> action return type.
068   * @return result of an action.
069   * @throws Exception whatever the action can throw.
070   */
071  @Override
072  public <T> T doAs(final PrivilegedExceptionAction<T> action) throws Exception {
073    return action.run();
074  }
075}