| /* |
| * * Copyright (C) 2021 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.modules.utils; |
| |
| import android.annotation.NonNull; |
| import android.os.Handler; |
| import android.os.HandlerThread; |
| |
| import com.android.internal.annotations.GuardedBy; |
| |
| import java.util.concurrent.Executor; |
| |
| /** |
| * Thread for asynchronous event processing. This thread is configured as |
| * {@link android.os.Process#THREAD_PRIORITY_BACKGROUND}, which means fewer CPU |
| * resources will be dedicated to it, and it will "have less chance of impacting |
| * the responsiveness of the user interface." |
| * <p> |
| * This thread is best suited for tasks that the user is not actively waiting |
| * for, or for tasks that the user expects to be executed eventually. |
| * |
| * @see com.android.internal.os.BackgroundThread |
| */ |
| public final class BackgroundThread extends HandlerThread { |
| private static final Object sLock = new Object(); |
| |
| @GuardedBy("sLock") |
| private static BackgroundThread sInstance; |
| @GuardedBy("sLock") |
| private static Handler sHandler; |
| @GuardedBy("sLock") |
| private static HandlerExecutor sHandlerExecutor; |
| |
| private BackgroundThread() { |
| super(BackgroundThread.class.getName(), android.os.Process.THREAD_PRIORITY_BACKGROUND); |
| } |
| |
| @GuardedBy("sLock") |
| private static void ensureThreadLocked() { |
| if (sInstance == null) { |
| sInstance = new BackgroundThread(); |
| sInstance.start(); |
| sHandler = new Handler(sInstance.getLooper()); |
| sHandlerExecutor = new HandlerExecutor(sHandler); |
| } |
| } |
| |
| /** |
| * Get the singleton instance of this class. |
| * |
| * @return the singleton instance of this class |
| */ |
| @NonNull |
| public static BackgroundThread get() { |
| synchronized (sLock) { |
| ensureThreadLocked(); |
| return sInstance; |
| } |
| } |
| |
| /** |
| * Get the singleton {@link Handler} for this class. |
| * |
| * @return the singleton {@link Handler} for this class. |
| */ |
| @NonNull |
| public static Handler getHandler() { |
| synchronized (sLock) { |
| ensureThreadLocked(); |
| return sHandler; |
| } |
| } |
| |
| /** |
| * Get the singleton {@link Executor} for this class. |
| * |
| * @return the singleton {@link Executor} for this class. |
| */ |
| @NonNull |
| public static Executor getExecutor() { |
| synchronized (sLock) { |
| ensureThreadLocked(); |
| return sHandlerExecutor; |
| } |
| } |
| } |