1/*
2 * Copyright (C) 2012 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.power;
18
19import android.util.proto.ProtoOutputStream;
20
21/**
22 * Low-level suspend blocker mechanism equivalent to holding a partial wake lock.
23 *
24 * This interface is used internally to avoid introducing internal dependencies
25 * on the high-level wake lock mechanism.
26 */
27interface SuspendBlocker {
28    /**
29     * Acquires the suspend blocker.
30     * Prevents the CPU from going to sleep.
31     *
32     * Calls to acquire() nest and must be matched by the same number
33     * of calls to release().
34     */
35    void acquire();
36
37    /**
38     * Releases the suspend blocker.
39     * Allows the CPU to go to sleep if no other suspend blockers are held.
40     *
41     * It is an error to call release() if the suspend blocker has not been acquired.
42     * The system may crash.
43     */
44    void release();
45
46    void writeToProto(ProtoOutputStream proto, long fieldId);
47}
48