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