1 /* <lambda>null2 * Copyright (C) 2019 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.permissioncontroller.permission.data 18 19 import android.os.Binder 20 import com.android.permissioncontroller.permission.utils.IPC 21 import kotlinx.coroutines.Dispatchers.Main 22 import kotlinx.coroutines.GlobalScope 23 import kotlinx.coroutines.Job 24 import kotlinx.coroutines.launch 25 26 /** 27 * A LiveData which loads its data in a background AsyncTask. It will cancel current tasks, if new 28 * requests come during execution 29 * 30 * @param isStaticVal Whether or not this LiveData value is expected to change 31 * @param alwaysUpdateOnActive Whether or not this LiveData should update upon going active 32 */ 33 abstract class SmartAsyncMediatorLiveData<T>( 34 isStaticVal: Boolean = false, 35 private val alwaysUpdateOnActive: Boolean = true 36 ) : SmartUpdateMediatorLiveData<T>(isStaticVal) { 37 38 private var currentJob: Job? = null 39 @Volatile 40 private var jobQueued = false 41 @Volatile 42 private var jobRunning = false 43 44 /** 45 * The main function which will load data. It should periodically check isCancelled to see if 46 * it should stop working. If data is loaded, it should call "postValue". 47 */ 48 abstract suspend fun loadDataAndPostValue(job: Job) 49 50 override fun onUpdate() { 51 updateAsync() 52 } 53 54 open fun updateAsync() { 55 if (jobRunning) { 56 jobQueued = true 57 return 58 } else { 59 jobRunning = true 60 } 61 62 GlobalScope.launch(IPC) { 63 currentJob = coroutineContext[Job] 64 loadDataAndPostValue(currentJob!!) 65 // TODO ntmyren: generalize this command to the IPC dispatcher 66 Binder.flushPendingCommands() 67 jobRunning = false 68 if (jobQueued) { 69 jobQueued = false 70 GlobalScope.launch(Main.immediate) { 71 updateAsync() 72 } 73 } 74 } 75 } 76 77 override fun onActive() { 78 super.onActive() 79 80 if (alwaysUpdateOnActive) { 81 updateAsync() 82 } 83 } 84 85 override fun onInactive() { 86 cancelJobIfRunning() 87 jobQueued = false 88 super.onInactive() 89 } 90 91 private fun cancelJobIfRunning() { 92 currentJob?.let { job -> 93 if (job.isActive) { 94 job.cancel() 95 } 96 } 97 } 98 }