components/proximity_auth/logging/log_buffer.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H
   6 #define COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H
   7
   8 #include <list>
   9
  10 #include "base/logging.h"
  11 #include "base/macros.h"
  12 #include "base/observer_list.h"
  13 #include "base/time/time.h"
  14
  15 namespace proximity_auth {
  16
  17 // Contains logs specific to the Proximity Auth. This buffer has a maximum size
  18 // and will discard entries in FIFO order.
  19 // Call LogBuffer::GetInstance() to get the global LogBuffer instance.
  20 class LogBuffer {
  21  public:
  22   // Represents a single log entry in the log buffer.
  23   struct LogMessage {
  24     const std::string text;
  25     const base::Time time;
  26     const std::string file;
  27     const int line;
  28     const logging::LogSeverity severity;
  29
  30     LogMessage(const std::string& text,
  31                const base::Time& time,
  32                const std::string& file,
  33                int line,
  34                logging::LogSeverity severity);
  35   };
  36
  37   class Observer {
  38    public:
  39     // Called when a new message is added to the log buffer.
  40     virtual void OnLogMessageAdded(const LogMessage& log_message) = 0;
  41
  42     // Called when all messages in the log buffer are cleared.
  43     virtual void OnLogBufferCleared() = 0;
  44   };
  45
  46   LogBuffer();
  47   ~LogBuffer();
  48
  49   // Returns the global instance.
  50   static LogBuffer* GetInstance();
  51
  52   // Adds and removes log buffer observers.
  53   void AddObserver(Observer* observer);
  54   void RemoveObserver(Observer* observer);
  55
  56   // Adds a new log message to the buffer. If the number of log messages exceeds
  57   // the maximum, then the earliest added log will be removed.
  58   void AddLogMessage(const LogMessage& log_message);
  59
  60   // Clears all logs in the buffer.
  61   void Clear();
  62
  63   // Returns the maximum number of logs that can be stored.
  64   size_t MaxBufferSize() const;
  65
  66   // Returns the list logs in the buffer, sorted chronologically.
  67   const std::list<LogMessage>* logs() { return &log_messages_; }
  68
  69  private:
  70   // The messages currently in the buffer.
  71   std::list<LogMessage> log_messages_;
  72
  73   // List of observers.
  74   base::ObserverList<Observer> observers_;
  75
  76   DISALLOW_COPY_AND_ASSIGN(LogBuffer);
  77 };
  78
  79 }  // namespace proximity_auth
  80
  81 #endif  // COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H