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
17package com.android.systemui.util.leak;
18
19import android.os.SystemClock;
20
21import java.lang.ref.Reference;
22import java.lang.ref.ReferenceQueue;
23import java.lang.ref.WeakReference;
24
25/**
26 * Utilities for writing tests that manipulate weak or other references.
27 */
28public class ReferenceTestUtils {
29
30    /** Returns a runnable that blocks until {@code o} has been collected. */
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
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 {
63        boolean apply();
64    }
65
66    public interface CollectionWaiter {
67        void waitForCollection();
68    }
69}
70