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