1 /*
<lambda>null2  * Copyright 2021 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 androidx.paging
18 
19 import androidx.kruth.assertWithMessage
20 import androidx.paging.internal.AtomicBoolean
21 import java.lang.ref.ReferenceQueue
22 import java.lang.ref.WeakReference
23 import kotlin.concurrent.thread
24 import kotlin.random.Random
25 import kotlin.reflect.KClass
26 import kotlin.time.Duration.Companion.seconds
27 
28 internal class GarbageCollectionTestHelper {
29     private val queue = ReferenceQueue<Any>()
30     private val references = mutableListOf<WeakReference<Any>>()
31     private var size = 0
32 
33     fun track(item: Any) {
34         references.add(WeakReference(item, queue))
35         size++
36     }
37 
38     fun assertLiveObjects(vararg expected: Pair<KClass<*>, Int>) {
39         val continueTriggeringGc = AtomicBoolean(true)
40         thread {
41             val leak: ArrayList<ByteArray> = ArrayList()
42             do {
43                 val arraySize = Random.nextInt(1000)
44                 leak.add(ByteArray(arraySize))
45                 System.gc()
46             } while (continueTriggeringGc.get())
47         }
48         var collectedItemCount = 0
49         val expectedItemCount = size - expected.sumOf { it.second }
50         while (
51             collectedItemCount < expectedItemCount &&
52                 queue.remove(5.seconds.inWholeMilliseconds) != null
53         ) {
54             collectedItemCount++
55         }
56         continueTriggeringGc.set(false)
57         val leakedObjects = countLiveObjects()
58         val leakedObjectToStrings = references.mapNotNull { it.get() }.joinToString("\n")
59         assertWithMessage("expected to collect $expectedItemCount, collected $collectedItemCount")
60             .that(collectedItemCount)
61             .isEqualTo(expectedItemCount)
62         assertWithMessage(
63                 """
64             expected to collect $expectedItemCount, collected $collectedItemCount.
65             live objects: $leakedObjectToStrings
66             """
67                     .trimIndent()
68             )
69             .that(leakedObjects)
70             .containsExactlyElementsIn(expected)
71     }
72 
73     /** Tries to trigger garbage collection until an element is available in the given queue. */
74     fun assertEverythingIsCollected() {
75         assertLiveObjects()
76     }
77 
78     private fun countLiveObjects(): List<Pair<KClass<*>, Int>> {
79         return references
80             .mapNotNull { it.get() }
81             .groupBy { it::class }
82             .map { entry -> entry.key to entry.value.size }
83     }
84 }
85