1 /*
2  * Copyright (C) 2024 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 com.example.tracing.demo.experiments
17 
18 import android.os.Trace
19 import com.android.app.tracing.coroutines.flow.collectTraced
20 import com.android.app.tracing.coroutines.flow.filterTraced as filter
21 import com.android.app.tracing.coroutines.flow.flowName
22 import com.android.app.tracing.coroutines.flow.mapTraced as map
23 import com.android.app.tracing.coroutines.launchTraced as launch
24 import com.example.tracing.demo.FixedThreadA
25 import com.example.tracing.demo.FixedThreadB
26 import com.example.tracing.demo.FixedThreadC
27 import javax.inject.Inject
28 import javax.inject.Singleton
29 import kotlinx.coroutines.CoroutineDispatcher
30 import kotlinx.coroutines.coroutineScope
31 import kotlinx.coroutines.flow.flowOn
32 
33 @Singleton
34 class CollectFlow
35 @Inject
36 constructor(
37     @FixedThreadA private var dispatcherA: CoroutineDispatcher,
38     @FixedThreadB private var dispatcherB: CoroutineDispatcher,
39     @FixedThreadC private val dispatcherC: CoroutineDispatcher,
40 ) : Experiment {
41     override val description: String = "Collect a cold flow with intermediate operators"
42 
43     private val coldFlow =
44         coldCounterFlow("count", 4)
45             .flowName("original-cold-flow-scope")
46             .flowOn(dispatcherA)
<lambda>null47             .filter("evens") {
48                 forceSuspend("B", 20)
49                 it % 2 == 0
50             }
51             .flowOn(dispatcherB)
52             .flowName("even-filter-scope")
<lambda>null53             .map("3x") {
54                 forceSuspend("C", 15)
55                 it * 3
56             }
57             .flowOn(dispatcherC)
58 
<lambda>null59     override suspend fun start(): Unit = coroutineScope {
60         launch(context = dispatcherA) {
61             coldFlow.collectTraced {
62                 Trace.instant(Trace.TRACE_TAG_APP, "got: $it")
63                 forceSuspend("A2", 60)
64             }
65         }
66     }
67 }
68