text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2018 The Talkcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef TALKCOIN_LOGGING_H
  #define TALKCOIN_LOGGING_H
  
  #include <fs.h>
  #include <tinyformat.h>
  
  #include <atomic>
  #include <cstdint>
  #include <list>
  #include <mutex>
  #include <string>
  #include <vector>
  
  static const bool DEFAULT_LOGTIMEMICROS = false;
  static const bool DEFAULT_LOGIPS        = false;
  static const bool DEFAULT_LOGTIMESTAMPS = true;
  static const bool DEFAULT_LOGTHREADNAMES = false;
  extern const char * const DEFAULT_DEBUGLOGFILE;
  
  extern bool fLogIPs;
  
  struct CLogCategoryActive
  {
      std::string category;
      bool active;
  };
  
  namespace BCLog {
      enum LogFlags : uint32_t {
          NONE        = 0,
          NET         = (1 <<  0),
          TOR         = (1 <<  1),
          MEMPOOL     = (1 <<  2),
          HTTP        = (1 <<  3),
          BENCH       = (1 <<  4),
          ZMQ         = (1 <<  5),
          DB          = (1 <<  6),
          RPC         = (1 <<  7),
          ESTIMATEFEE = (1 <<  8),
          ADDRMAN     = (1 <<  9),
          SELECTCOINS = (1 << 10),
          REINDEX     = (1 << 11),
          CMPCTBLOCK  = (1 << 12),
          RAND        = (1 << 13),
          PRUNE       = (1 << 14),
          PROXY       = (1 << 15),
          MEMPOOLREJ  = (1 << 16),
          LIBEVENT    = (1 << 17),
          COINDB      = (1 << 18),
          QT          = (1 << 19),
          LEVELDB     = (1 << 20),
  #ifdef ENABLE_PROOF_OF_STAKE
          COINSTAKE   = (1 << 21),
  #endif
  #ifdef ENABLE_SECURE_MESSAGING
          SMSG   = (1 << 22),
  #endif
          ALL         = ~(uint32_t)0,
      };
  
      class Logger
      {
      private:
          mutable std::mutex m_cs;                   // Can not use Mutex from sync.h because in debug mode it would cause a deadlock when a potential deadlock was detected
          FILE* m_fileout = nullptr;                 // GUARDED_BY(m_cs)
          std::list<std::string> m_msgs_before_open; // GUARDED_BY(m_cs)
          bool m_buffering{true};                    //!< Buffer messages before logging can be started. GUARDED_BY(m_cs)
  
          /**
           * m_started_new_line is a state variable that will suppress printing of
           * the timestamp when multiple calls are made that don't end in a
           * newline.
           */
          std::atomic_bool m_started_new_line{true};
  
          /** Log categories bitfield. */
          std::atomic<uint32_t> m_categories{0};
  
          std::string LogTimestampStr(const std::string& str);
  
      public:
          bool m_print_to_console = false;
          bool m_print_to_file = false;
  
          bool m_log_timestamps = DEFAULT_LOGTIMESTAMPS;
          bool m_log_time_micros = DEFAULT_LOGTIMEMICROS;
          bool m_log_threadnames = DEFAULT_LOGTHREADNAMES;
  
          fs::path m_file_path;
          std::atomic<bool> m_reopen_file{false};
  
          /** Send a string to the log output */
          void LogPrintStr(const std::string& str);
  
          /** Returns whether logs will be written to any output */
          bool Enabled() const
          {
              std::lock_guard<std::mutex> scoped_lock(m_cs);
              return m_buffering || m_print_to_console || m_print_to_file;
          }
  
          /** Start logging (and flush all buffered messages) */
          bool StartLogging();
          /** Only for testing */
          void DisconnectTestLogger();
  
          void ShrinkDebugFile();
  
          uint32_t GetCategoryMask() const { return m_categories.load(); }
  
          void EnableCategory(LogFlags flag);
          bool EnableCategory(const std::string& str);
          void DisableCategory(LogFlags flag);
          bool DisableCategory(const std::string& str);
  
          bool WillLogCategory(LogFlags category) const;
  
          bool DefaultShrinkDebugFile() const;
      };
  
  } // namespace BCLog
  
  BCLog::Logger& LogInstance();
  
  /** Return true if log accepts specified category */
  static inline bool LogAcceptCategory(BCLog::LogFlags category)
  {
      return LogInstance().WillLogCategory(category);
  }
  
  /** Returns a string with the log categories. */
  std::string ListLogCategories();
  
  /** Returns a vector of the active log categories. */
  std::vector<CLogCategoryActive> ListActiveLogCategories();
  
  /** Return true if str parses as a log category and set the flag */
  bool GetLogCategory(BCLog::LogFlags& flag, const std::string& str);
  
  // Be conservative when using LogPrintf/error or other things which
  // unconditionally log to debug.log! It should not be the case that an inbound
  // peer can fill up a user's disk with debug.log entries.
  
  template <typename... Args>
  static inline void LogPrintf(const char* fmt, const Args&... args)
  {
      if (LogInstance().Enabled()) {
          std::string log_msg;
          try {
              log_msg = tfm::format(fmt, args...);
          } catch (tinyformat::format_error& fmterr) {
              /* Original format string will have newline so don't add one here */
              log_msg = "Error \"" + std::string(fmterr.what()) + "\" while formatting log message: " + fmt;
          }
          LogInstance().LogPrintStr(log_msg);
      }
  }
  
  template <typename... Args>
  static inline void LogPrint(const BCLog::LogFlags& category, const Args&... args)
  {
      if (LogAcceptCategory((category))) {
          LogPrintf(args...);
      }
  }
  
  #endif // TALKCOIN_LOGGING_H
  