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      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. */
     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