1 /* 2 * Copyright (C) 2013 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 17 package com.android.internal.os; 18 19 import android.annotation.NonNull; 20 import android.os.Handler; 21 import android.os.HandlerExecutor; 22 import android.os.HandlerThread; 23 import android.os.Looper; 24 import android.os.Trace; 25 26 import java.util.concurrent.Executor; 27 28 /** 29 * Shared singleton background thread for each process. 30 */ 31 @android.ravenwood.annotation.RavenwoodKeepWholeClass 32 public final class BackgroundThread extends HandlerThread { 33 private static final long SLOW_DISPATCH_THRESHOLD_MS = 10_000; 34 private static final long SLOW_DELIVERY_THRESHOLD_MS = 30_000; 35 private static BackgroundThread sInstance; 36 private static Handler sHandler; 37 private static HandlerExecutor sHandlerExecutor; 38 BackgroundThread()39 private BackgroundThread() { 40 super("android.bg", android.os.Process.THREAD_PRIORITY_BACKGROUND); 41 } 42 ensureThreadLocked()43 private static void ensureThreadLocked() { 44 if (sInstance == null) { 45 sInstance = new BackgroundThread(); 46 sInstance.start(); 47 final Looper looper = sInstance.getLooper(); 48 looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER); 49 looper.setSlowLogThresholdMs( 50 SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS); 51 sHandler = new Handler(sInstance.getLooper(), /*callback=*/ null, /* async=*/ false, 52 /* shared=*/ true); 53 sHandlerExecutor = new HandlerExecutor(sHandler); 54 } 55 } 56 57 @NonNull get()58 public static BackgroundThread get() { 59 synchronized (BackgroundThread.class) { 60 ensureThreadLocked(); 61 return sInstance; 62 } 63 } 64 65 @NonNull getHandler()66 public static Handler getHandler() { 67 synchronized (BackgroundThread.class) { 68 ensureThreadLocked(); 69 return sHandler; 70 } 71 } 72 73 @NonNull getExecutor()74 public static Executor getExecutor() { 75 synchronized (BackgroundThread.class) { 76 ensureThreadLocked(); 77 return sHandlerExecutor; 78 } 79 } 80 } 81