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