content: /*
   * Copyright (C) 2019 The Android Open Source Project
   *
   * 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 com.android.server.connectivity;
  
  import android.annotation.NonNull;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  /**
   * A ref that autodestructs at the first usage of it.
   * @param <T> The type of the held object
   * @hide
   */
  public class AutodestructReference<T> {
      private final AtomicReference<T> mHeld;
      public AutodestructReference(@NonNull T obj) {
          if (null == obj) throw new NullPointerException("Autodestruct reference to null");
          mHeld = new AtomicReference<>(obj);
      }
  
      /** Get the ref and destruct it. NPE if already destructed. */
      @NonNull
      public T getAndDestroy() {
          final T obj = mHeld.getAndSet(null);
          if (null == obj) throw new NullPointerException("Already autodestructed");
          return obj;
      }
  }
  