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/*
* * Copyright (C) 2024 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 android.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
*
* TODO: b/326916057 depend on modules-utils-backgroundthread instead
* @hide
*/
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;
}
}
}
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