/* * * 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." *
* 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; } } }