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