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.server; 18 19 import android.os.Handler; 20 import android.os.Trace; 21 22 /** 23 * Shared singleton thread for showing UI. This is a foreground thread, and in 24 * additional should not have operations that can take more than a few ms scheduled 25 * on it to avoid UI jank. 26 */ 27 public final class UiThread extends ServiceThread { 28 private static UiThread sInstance; 29 private static Handler sHandler; 30 31 private UiThread() { 32 super("android.ui", android.os.Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/); 33 } 34 35 private static void ensureThreadLocked() { 36 if (sInstance == null) { 37 sInstance = new UiThread(); 38 sInstance.start(); 39 sInstance.getLooper().setTraceTag(Trace.TRACE_TAG_ACTIVITY_MANAGER); 40 sHandler = new Handler(sInstance.getLooper()); 41 } 42 } 43 44 public static UiThread get() { 45 synchronized (UiThread.class) { 46 ensureThreadLocked(); 47 return sInstance; 48 } 49 } 50 51 public static Handler getHandler() { 52 synchronized (UiThread.class) { 53 ensureThreadLocked(); 54 return sHandler; 55 } 56 } 57 } 58
