1 /*
2  * Copyright (C) 2020 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 #ifndef CHRE_PLATFORM_LINUX_PLATFORM_LOG_H_
18 #define CHRE_PLATFORM_LINUX_PLATFORM_LOG_H_
19 
20 #include <condition_variable>
21 #include <mutex>
22 #include <queue>
23 #include <thread>
24 
25 #include "chre/util/singleton.h"
26 #include "chre_api/chre/re.h"
27 
28 namespace chre {
29 
30 /**
31  * Storage for the Linux implementation of the PlatformLog class.
32  */
33 class PlatformLog {
34  public:
35   PlatformLog();
36 
37   ~PlatformLog();
38 
39   /**
40    * Logs message with printf-style arguments. No trailing newline is required
41    * for this method.
42    */
log(chreLogLevel logLevel,const char * formatStr,...)43   void log(chreLogLevel logLevel, const char *formatStr, ...) {
44     va_list args;
45     va_start(args, formatStr);
46     logVa(logLevel, formatStr, args);
47     va_end(args);
48   }
49 
50   /**
51    * Logs message with printf-style arguments. No trailing newline is required
52    * for this method. Uses va_list parameter instead of ...
53    */
54   void logVa(chreLogLevel logLevel, const char *formatStr, va_list args);
55 
56  private:
57   /**
58    * A looper method that idles on a condition variable on logs becoming
59    * available. When logs are available, they are output via std::cout.
60    */
61   void logLooper();
62 
63   //! The thread that waits on incoming log messages and sends them out to
64   //! std::cout.
65   std::thread mLoggerThread;
66 
67   //! A mutex to guard the shared queue and exit condition of this class.
68   std::mutex mMutex;
69 
70   //! The condition variable to signal that the log looper has messages
71   //! available to output.
72   std::condition_variable mConditionVariable;
73 
74   //! A queue of incoming log messages.
75   std::queue<char *> mLogQueue;
76 
77   //! A flag to indicate that the logger should shut down.
78   bool mStopLogger = false;
79 };
80 
81 typedef Singleton<PlatformLog> PlatformLogSingleton;
82 
83 }  // namespace chre
84 
85 #endif  // CHRE_PLATFORM_LINUX_PLATFORM_LOG_H_
86