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.Process; 21 import android.os.Trace; 22 23 /** 24 * Shared singleton foreground thread for the system. This is a thread for 25 * operations that affect what's on the display, which needs to have a minimum 26 * of latency. This thread should pretty much only be used by the WindowManager, 27 * DisplayManager, and InputManager to perform quick operations in real time. 28 */ 29 public final class DisplayThread extends ServiceThread { 30 private static DisplayThread sInstance; 31 private static Handler sHandler; 32 33 private DisplayThread() { 34 // DisplayThread runs important stuff, but these are not as important as things running in 35 // AnimationThread. Thus, set the priority to one lower. 36 super("android.display", Process.THREAD_PRIORITY_DISPLAY + 1, false /*allowIo*/); 37 } 38 39 private static void ensureThreadLocked() { 40 if (sInstance == null) { 41 sInstance = new DisplayThread(); 42 sInstance.start(); 43 sInstance.getLooper().setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER); 44 sHandler = new Handler(sInstance.getLooper()); 45 } 46 } 47 48 public static DisplayThread get() { 49 synchronized (DisplayThread.class) { 50 ensureThreadLocked(); 51 return sInstance; 52 } 53 } 54 55 public static Handler getHandler() { 56 synchronized (DisplayThread.class) { 57 ensureThreadLocked(); 58 return sHandler; 59 } 60 } 61 } 62
