1 /*
2  * Copyright (C) 2017 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.systemui.util.leak;
18 
19 import android.os.SystemClock;
20 
21 import java.lang.ref.Reference;
22 import java.lang.ref.ReferenceQueue;
23 import java.lang.ref.WeakReference;
24 
25 /**
26  * Utilities for writing tests that manipulate weak or other references.
27  */
28 public class ReferenceTestUtils {
29 
30     /** Returns a runnable that blocks until {@code o} has been collected. */
createCollectionWaiter(Object o)31     public static CollectionWaiter createCollectionWaiter(Object o) {
32         ReferenceQueue<Object> q = new ReferenceQueue<>();
33         Reference<?> ref = new WeakReference<>(o, q);
34         o = null; // Ensure this variable can't be referenced from the lambda.
35 
36         return () -> {
37             Runtime.getRuntime().gc();
38             while (true) {
39                 try {
40                     if (q.remove(5_000) == ref) {
41                         return;
42                     } else {
43                         throw new RuntimeException("timeout while waiting for object collection");
44                     }
45                 } catch (InterruptedException e) {
46                     Thread.currentThread().interrupt();
47                 }
48             }
49         };
50     }
51 
waitForCondition(Condition p)52     public static void waitForCondition(Condition p) {
53         long deadline = SystemClock.uptimeMillis() + 5_000;
54         while (!p.apply()) {
55             if (SystemClock.uptimeMillis() > deadline) {
56                 throw new RuntimeException("timeout while waiting for condition");
57             }
58             SystemClock.sleep(100);
59         }
60     }
61 
62     public interface Condition {
apply()63         boolean apply();
64     }
65 
66     public interface CollectionWaiter {
waitForCollection()67         void waitForCollection();
68     }
69 }
70