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.Trace;
21
22/**
23 * Shared singleton foreground thread for the system.  This is a thread for regular
24 * foreground service operations, which shouldn't be blocked by anything running in
25 * the background.  In particular, the shared background thread could be doing
26 * relatively long-running operations like saving state to disk (in addition to
27 * simply being a background priority), which can cause operations scheduled on it
28 * to be delayed for a user-noticeable amount of time.
29 */
30public final class FgThread extends ServiceThread {
31    private static FgThread sInstance;
32    private static Handler sHandler;
33
34    private FgThread() {
35        super("android.fg", android.os.Process.THREAD_PRIORITY_DEFAULT, true /*allowIo*/);
36    }
37
38    private static void ensureThreadLocked() {
39        if (sInstance == null) {
40            sInstance = new FgThread();
41            sInstance.start();
42            sInstance.getLooper().setTraceTag(Trace.TRACE_TAG_ACTIVITY_MANAGER);
43            sHandler = new Handler(sInstance.getLooper());
44        }
45    }
46
47    public static FgThread get() {
48        synchronized (UiThread.class) {
49            ensureThreadLocked();
50            return sInstance;
51        }
52    }
53
54    public static Handler getHandler() {
55        synchronized (UiThread.class) {
56            ensureThreadLocked();
57            return sHandler;
58        }
59    }
60}
61