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 "TimeKeeper.h"
20 
21 #include <android-base/thread_annotations.h>
22 #include <array>
23 #include <thread>
24 
25 namespace android::scheduler {
26 
27 class Timer : public TimeKeeper {
28 public:
29     Timer();
30     ~Timer();
31     nsecs_t now() const final;
32 
33     // NB: alarmIn and alarmCancel are threadsafe; with the last-returning function being effectual
34     //     Most users will want to serialize thes calls so as to be aware of the timer state.
35     void alarmIn(std::function<void()> const& cb, nsecs_t fireIn) final;
36     void alarmCancel() final;
37     void dump(std::string& result) const final;
38 
39 private:
40     enum class DebugState { Reset, Running, Waiting, Reading, InCallback, Terminated };
41     void reset();
42     void cleanup();
43     void setDebugState(DebugState state) EXCLUDES(mMutex);
44     const char* strDebugState(DebugState state) const;
45 
46     int mTimerFd = -1;
47     int mEpollFd = -1;
48     std::array<int, 2> mPipes = {-1, -1};
49 
50     std::thread mDispatchThread;
51     void threadMain();
52     bool dispatch();
53     void endDispatch();
54 
55     mutable std::mutex mMutex;
56     std::function<void()> mCallback GUARDED_BY(mMutex);
57     DebugState mDebugState GUARDED_BY(mMutex);
58 };
59 
60 } // namespace android::scheduler
61