1 /* 2 * Copyright (C) 2018 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.android.launcher3.util; 17 18 import static com.android.launcher3.util.Executors.MAIN_EXECUTOR; 19 20 import android.content.Context; 21 import android.os.Looper; 22 23 import androidx.annotation.VisibleForTesting; 24 25 import com.android.launcher3.graphics.LauncherPreviewRenderer.PreviewContext; 26 import com.android.launcher3.util.ResourceBasedOverride.Overrides; 27 28 import java.util.concurrent.ExecutionException; 29 30 /** 31 * Utility class for defining singletons which are initiated on main thread. 32 */ 33 public class MainThreadInitializedObject<T> { 34 35 private final ObjectProvider<T> mProvider; 36 private T mValue; 37 MainThreadInitializedObject(ObjectProvider<T> provider)38 public MainThreadInitializedObject(ObjectProvider<T> provider) { 39 mProvider = provider; 40 } 41 get(Context context)42 public T get(Context context) { 43 if (context instanceof PreviewContext) { 44 return ((PreviewContext) context).getObject(this, mProvider); 45 } 46 47 if (mValue == null) { 48 if (Looper.myLooper() == Looper.getMainLooper()) { 49 mValue = TraceHelper.allowIpcs("main.thread.object", 50 () -> mProvider.get(context.getApplicationContext())); 51 } else { 52 try { 53 return MAIN_EXECUTOR.submit(() -> get(context)).get(); 54 } catch (InterruptedException|ExecutionException e) { 55 throw new RuntimeException(e); 56 } 57 } 58 } 59 return mValue; 60 } 61 getNoCreate()62 public T getNoCreate() { 63 return mValue; 64 } 65 66 @VisibleForTesting initializeForTesting(T value)67 public void initializeForTesting(T value) { 68 mValue = value; 69 } 70 71 /** 72 * Initializes a provider based on resource overrides 73 */ forOverride( Class<T> clazz, int resourceId)74 public static <T extends ResourceBasedOverride> MainThreadInitializedObject<T> forOverride( 75 Class<T> clazz, int resourceId) { 76 return new MainThreadInitializedObject<>(c -> Overrides.getObject(clazz, c, resourceId)); 77 } 78 79 public interface ObjectProvider<T> { 80 get(Context context)81 T get(Context context); 82 } 83 } 84