1 /*
2  * 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 package androidx.testutils
17 
18 import java.util.concurrent.Executor
19 import java.util.concurrent.ExecutorService
20 import java.util.concurrent.Executors
21 import java.util.concurrent.TimeUnit
22 import java.util.concurrent.locks.ReentrantLock
23 import kotlin.concurrent.withLock
24 import kotlinx.coroutines.flow.MutableStateFlow
25 import kotlinx.coroutines.flow.filter
26 import kotlinx.coroutines.flow.first
27 import kotlinx.coroutines.withTimeout
28 
29 /**
30  * An executor that can block some known runnables. We use it to slow down database invalidation
31  * events.
32  */
33 class FilteringExecutor(
34     private val delegate: ExecutorService = Executors.newSingleThreadExecutor()
35 ) : Executor {
36     private val deferred = mutableListOf<Runnable>()
37     private val deferredSize = MutableStateFlow(0)
38     private val lock = ReentrantLock()
39 
<lambda>null40     var filterFunction: (Runnable) -> Boolean = { true }
41         set(value) {
42             field = value
43             reEnqueueDeferred()
44         }
45 
<lambda>null46     suspend fun awaitDeferredSizeAtLeast(min: Int) = withTestTimeout {
47         deferredSize.filter { it >= min }.first()
48     }
49 
reEnqueueDeferrednull50     private fun reEnqueueDeferred() {
51         val copy =
52             lock.withLock {
53                 val copy = deferred.toMutableList()
54                 deferred.clear()
55                 deferredSize.value = 0
56                 copy
57             }
58         copy.forEach(this::execute)
59     }
60 
deferredSizenull61     fun deferredSize(): Int {
62         return deferred.size
63     }
64 
executeAllnull65     fun executeAll() {
66         while (deferred.isNotEmpty()) {
67             deferred.removeFirst().run()
68         }
69     }
70 
executeLatestDeferrednull71     fun executeLatestDeferred() {
72         deferred.removeLast().run()
73     }
74 
executenull75     override fun execute(command: Runnable) {
76         lock.withLock {
77             if (filterFunction(command)) {
78                 delegate.execute(command)
79             } else {
80                 deferred.add(command)
81                 deferredSize.value += 1
82             }
83         }
84     }
85 }
86 
withTestTimeoutnull87 suspend fun <T> withTestTimeout(duration: Long = 3, block: suspend () -> T): T {
88     try {
89         return withTimeout(timeMillis = TimeUnit.SECONDS.toMillis(duration)) { block() }
90     } catch (err: Throwable) {
91         throw AssertionError("didn't complete in expected time", err)
92     }
93 }
94