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 <functional>
20 #include <memory>
21 #include <mutex>
22 
23 #include "common/callback.h"
24 #include "os/handler.h"
25 #include "os/thread.h"
26 #include "os/utils.h"
27 
28 namespace bluetooth {
29 namespace os {
30 
31 // A single-shot alarm for reactor-based thread, implemented by Linux timerfd.
32 // When it's constructed, it will register a reactable on the specified thread; when it's destroyed,
33 // it will unregister itself from the thread.
34 class Alarm {
35 public:
36   // Create and register a single-shot alarm on a given handler. This creates a wake alarm.
37   explicit Alarm(Handler* handler);
38 
39   // Create and register a single-shot alarm on a given handler.
40   // This constructor can specify whether the alarm will be a wake alarm or a non-wake alarm.
41   explicit Alarm(Handler* handler, bool isWakeAlarm);
42 
43   Alarm(const Alarm&) = delete;
44   Alarm& operator=(const Alarm&) = delete;
45 
46   // Unregister this alarm from the thread and release resource
47   ~Alarm();
48 
49   // Schedule the alarm with given delay
50   void Schedule(common::OnceClosure task, std::chrono::milliseconds delay);
51 
52   // Cancel the alarm. No-op if it's not armed.
53   void Cancel();
54 
55 private:
56   common::OnceClosure task_;
57   Handler* handler_;
58   int fd_ = 0;
59   Reactor::Reactable* token_;
60   mutable std::mutex mutex_;
61   void on_fire();
62 };
63 
64 }  // namespace os
65 
66 }  // namespace bluetooth
67