1 /*
2  * Copyright 2019 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 #pragma once
18 
19 #include "os/utils.h"
20 
21 namespace bluetooth {
22 namespace os {
23 
24 // A event_fd work in non-blocking and Semaphore mode
25 class ReactiveSemaphore {
26  public:
27   // Creates a new ReactiveSemaphore with an initial value of |value|.
28   explicit ReactiveSemaphore(unsigned int value);
29 
30   ReactiveSemaphore(const ReactiveSemaphore&) = delete;
31   ReactiveSemaphore& operator=(const ReactiveSemaphore&) = delete;
32 
33   ~ReactiveSemaphore();
34   // Decrements the value of |fd_|, this will cause a crash if |fd_| unreadable.
35   void Decrease();
36   // Increase the value of |fd_|, this will cause a crash if |fd_| unwritable.
37   void Increase();
38   int GetFd();
39 
40  private:
41   int fd_;
42 };
43 
44 }  // namespace os
45 }  // namespace bluetooth
46