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; 20 21/** 22 * Shared singleton thread for showing UI. This is a foreground thread, and in 23 * additional should not have operations that can take more than a few ms scheduled 24 * on it to avoid UI jank. 25 */ 26public final class UiThread extends ServiceThread { 27 private static UiThread sInstance; 28 private static Handler sHandler; 29 30 private UiThread() { 31 super("android.ui", android.os.Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/); 32 } 33 34 private static void ensureThreadLocked() { 35 if (sInstance == null) { 36 sInstance = new UiThread(); 37 sInstance.start(); 38 sHandler = new Handler(sInstance.getLooper()); 39 } 40 } 41 42 public static UiThread get() { 43 synchronized (UiThread.class) { 44 ensureThreadLocked(); 45 return sInstance; 46 } 47 } 48 49 public static Handler getHandler() { 50 synchronized (UiThread.class) { 51 ensureThreadLocked(); 52 return sHandler; 53 } 54 } 55} 56