UiThread.java revision 9158825f9c41869689d6b1786d7c7aa8bdd524ce 
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.HandlerThread;
21import android.os.StrictMode;
22import android.util.Slog;
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 HandlerThread {
30    private static UiThread sInstance;
31    private static Handler sHandler;
32
33    private UiThread() {
34        super("android.ui", android.os.Process.THREAD_PRIORITY_FOREGROUND);
35    }
36
37    private static void ensureThreadLocked() {
38        if (sInstance == null) {
39            sInstance = new UiThread();
40            sInstance.start();
41            sHandler = new Handler(sInstance.getLooper());
42            sHandler.post(new Runnable() {
43                @Override
44                public void run() {
45                    //Looper.myLooper().setMessageLogging(new LogPrinter(
46                    //        Log.VERBOSE, "WindowManagerPolicy", Log.LOG_ID_SYSTEM));
47                    android.os.Process.setCanSelfBackground(false);
48
49                    // For debug builds, log event loop stalls to dropbox for analysis.
50                    if (StrictMode.conditionallyEnableDebugLogging()) {
51                        Slog.i("UiThread", "Enabled StrictMode logging for UI thread");
52                    }
53                }
54            });
55        }
56    }
57
58    public static UiThread get() {
59        synchronized (UiThread.class) {
60            ensureThreadLocked();
61            return sInstance;
62        }
63    }
64
65    public static Handler getHandler() {
66        synchronized (UiThread.class) {
67            ensureThreadLocked();
68            return sHandler;
69        }
70    }
71}
72