1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.server.connectivity; 18 19 import android.annotation.NonNull; 20 21 import java.util.concurrent.atomic.AtomicReference; 22 23 /** 24 * A ref that autodestructs at the first usage of it. 25 * @param <T> The type of the held object 26 * @hide 27 */ 28 public class AutodestructReference<T> { 29 private final AtomicReference<T> mHeld; AutodestructReference(@onNull T obj)30 public AutodestructReference(@NonNull T obj) { 31 if (null == obj) throw new NullPointerException("Autodestruct reference to null"); 32 mHeld = new AtomicReference<>(obj); 33 } 34 35 /** Get the ref and destruct it. NPE if already destructed. */ 36 @NonNull getAndDestroy()37 public T getAndDestroy() { 38 final T obj = mHeld.getAndSet(null); 39 if (null == obj) throw new NullPointerException("Already autodestructed"); 40 return obj; 41 } 42 } 43