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 17package com.android.server; 18 19import android.os.Handler; 20import android.os.Looper; 21import android.os.Process; 22import android.os.Trace; 23 24/** 25 * Shared singleton thread for showing UI. This is a foreground thread, and in 26 * additional should not have operations that can take more than a few ms scheduled 27 * on it to avoid UI jank. 28 */ 29public final class UiThread extends ServiceThread { 30 private static final long SLOW_DISPATCH_THRESHOLD_MS = 100; 31 private static UiThread sInstance; 32 private static Handler sHandler; 33 34 private UiThread() { 35 super("android.ui", Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/); 36 } 37 38 @Override 39 public void run() { 40 // Make sure UiThread is in the fg stune boost group 41 Process.setThreadGroup(Process.myTid(), Process.THREAD_GROUP_TOP_APP); 42 super.run(); 43 } 44 45 private static void ensureThreadLocked() { 46 if (sInstance == null) { 47 sInstance = new UiThread(); 48 sInstance.start(); 49 final Looper looper = sInstance.getLooper(); 50 looper.setTraceTag(Trace.TRACE_TAG_ACTIVITY_MANAGER); 51 looper.setSlowDispatchThresholdMs(SLOW_DISPATCH_THRESHOLD_MS); 52 sHandler = new Handler(sInstance.getLooper()); 53 } 54 } 55 56 public static UiThread get() { 57 synchronized (UiThread.class) { 58 ensureThreadLocked(); 59 return sInstance; 60 } 61 } 62 63 public static Handler getHandler() { 64 synchronized (UiThread.class) { 65 ensureThreadLocked(); 66 return sHandler; 67 } 68 } 69} 70