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