Soonil Nagarkar | b6375a4 | 2020-01-29 15:23:06 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2020 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.server.location; |
| 18 | |
| 19 | import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND_SERVICE; |
| 20 | import static android.app.ActivityManager.RunningAppProcessInfo.Importance; |
| 21 | |
| 22 | import android.annotation.Nullable; |
| 23 | import android.app.ActivityManager; |
| 24 | import android.content.Context; |
| 25 | import android.os.Binder; |
| 26 | |
| 27 | import com.android.internal.annotations.GuardedBy; |
| 28 | import com.android.internal.util.Preconditions; |
| 29 | import com.android.server.FgThread; |
| 30 | |
| 31 | import java.util.Objects; |
| 32 | import java.util.concurrent.CopyOnWriteArrayList; |
| 33 | |
| 34 | /** |
| 35 | * Provides accessors and listeners for all application foreground status. An application is |
| 36 | * considered foreground if it's uid's importance level is at or more important than |
| 37 | * {@link android.app.ActivityManager.RunningAppProcessInfo#IMPORTANCE_FOREGROUND_SERVICE}. |
| 38 | */ |
| 39 | public class AppForegroundHelper { |
| 40 | |
| 41 | /** |
| 42 | * Listener for application foreground state changes. |
| 43 | */ |
| 44 | public interface AppForegroundListener { |
| 45 | /** |
| 46 | * Called when an application's foreground state changes. |
| 47 | */ |
| 48 | void onAppForegroundChanged(int uid, boolean foreground); |
| 49 | } |
| 50 | |
| 51 | // importance constants decrement with increasing importance - this is our limit for an |
| 52 | // importance level we consider foreground. |
| 53 | private static final int FOREGROUND_IMPORTANCE_CUTOFF = IMPORTANCE_FOREGROUND_SERVICE; |
| 54 | |
| 55 | private static boolean isForeground(@Importance int importance) { |
| 56 | return importance <= FOREGROUND_IMPORTANCE_CUTOFF; |
| 57 | } |
| 58 | |
| 59 | private final Context mContext; |
| 60 | private final CopyOnWriteArrayList<AppForegroundListener> mListeners; |
| 61 | |
| 62 | @GuardedBy("this") |
| 63 | @Nullable private ActivityManager mActivityManager; |
| 64 | |
| 65 | public AppForegroundHelper(Context context) { |
| 66 | mContext = context; |
| 67 | mListeners = new CopyOnWriteArrayList<>(); |
| 68 | } |
| 69 | |
| 70 | /** Called when system is ready. */ |
| 71 | public synchronized void onSystemReady() { |
| 72 | if (mActivityManager != null) { |
| 73 | return; |
| 74 | } |
| 75 | |
| 76 | mActivityManager = Objects.requireNonNull(mContext.getSystemService(ActivityManager.class)); |
| 77 | mActivityManager.addOnUidImportanceListener(this::onAppForegroundChanged, |
| 78 | FOREGROUND_IMPORTANCE_CUTOFF); |
| 79 | } |
| 80 | |
| 81 | /** |
| 82 | * Adds a listener for app foreground changed events. Callbacks occur on an unspecified thread. |
| 83 | */ |
| 84 | public void addListener(AppForegroundListener listener) { |
| 85 | mListeners.add(listener); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Removes a listener for app foreground changed events. |
| 90 | */ |
| 91 | public void removeListener(AppForegroundListener listener) { |
| 92 | mListeners.remove(listener); |
| 93 | } |
| 94 | |
| 95 | private void onAppForegroundChanged(int uid, @Importance int importance) { |
| 96 | // invoked on ui thread, move to fg thread so we don't block the ui thread |
| 97 | boolean foreground = isForeground(importance); |
| 98 | FgThread.getHandler().post(() -> { |
| 99 | for (AppForegroundListener listener : mListeners) { |
| 100 | listener.onAppForegroundChanged(uid, foreground); |
| 101 | } |
| 102 | }); |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Whether the given uid is currently foreground. |
| 107 | */ |
| 108 | public boolean isAppForeground(int uid) { |
| 109 | return isForeground(getImportance(uid)); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Retrieves the current importance of the given uid. |
| 114 | * |
| 115 | * @deprecated Prefer {@link #isAppForeground(int)}. |
| 116 | */ |
| 117 | @Deprecated |
| 118 | @Importance |
| 119 | public int getImportance(int uid) { |
| 120 | synchronized (this) { |
| 121 | Preconditions.checkState(mActivityManager != null); |
| 122 | } |
| 123 | |
| 124 | long identity = Binder.clearCallingIdentity(); |
| 125 | try { |
| 126 | return mActivityManager.getUidImportance(uid); |
| 127 | } finally { |
| 128 | Binder.restoreCallingIdentity(identity); |
| 129 | } |
| 130 | } |
| 131 | } |