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