1 /*
2  * Copyright (C) 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 <atomic>
20 #include <list>
21 #include <map>
22 #include <memory>
23 #include <mutex>
24 #include <thread>
25 
26 #include <json/json.h>
27 
28 #include "common/libs/fs/shared_fd.h"
29 
30 namespace cuttlefish {
31 
32 // Listen to kernel log events and report them to clients.
33 struct KernelLogEventsHandler {
34   explicit KernelLogEventsHandler(SharedFD kernel_log_fd);
35 
36   ~KernelLogEventsHandler();
37 
38   int AddSubscriber(std::function<void(const Json::Value&)> subscriber);
39   void Unsubscribe(int subscriber_id);
40  private:
41   void ReadLoop();
42   void DeliverEvent(const Json::Value& event);
43 
44   SharedFD kernel_log_fd_;
45   SharedFD eventfd_;
46   std::atomic<bool> running_;
47   std::thread read_thread_;
48   std::map<int, std::function<void(const Json::Value&)>> subscribers_;
49   int last_subscriber_id_ = 0;
50   std::mutex subscribers_mtx_;
51   std::list<Json::Value> last_events_;
52 };
53 
54 }  // namespace cuttlefish
55