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