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Logger

Purpose

The purpose of the logger is to log messages with different log levels such as info, debug in a file on the SPIFFS and print the information either at the beginning of the program via the serial monitor or directly during the program, depending on the configuration

The aim of these is to inform the user about the device status and to simplify and speed up debugging.

Implementation

The configuration described below is passed to the program via the config file.

Log levels

For the logging one of the following log levels can be selected:

  1. LOG_LEVEL_OFF

    No logging.

  2. LOG_LEVEL_FATAL

    Designates very severe error events that will presumably lead the application to abort.

  3. LOG_LEVEL_ERROR

    Designates error events that might still allow the application to continue running.

  4. LOG_LEVEL_WARNING

    Designates potentially harmful situations.

  5. LOG_LEVEL_INFO

    Designates informational messages that highlight the progress of the application at coarse-grained level.

  6. LOG_LEVEL_DEBUG

    Designates fine-grained informational events that are most useful to debug an application.

Note

For example, if INFO is selected, WARNING, ERROR and FATAL messages will still be logged, but DEBUG messages will not. This is how the levels work.

Logging

For the output one of the following options can be selected:

  1. LOG_OUTPUT_SERIAL_DIRECT

    Logging events are directly printed over serial interface when they occure.

  2. LOG_OUTPUT_SERIAL_BEGIN

    Logging events are stored in the SPIFFS and printed over the serial interface at the start of the program.

  3. LOG_OUTPUT_SERIAL_DIRECT_BEGIN

    Comibination of LOG_OUTPUT_SERIAL_DIRECT and LOG_OUTPUT_SERIAL_BEGIN.

  4. LOG_OUTPUT_OFF

    Not output at all.

Log file storage

The logged information is stored in three files on the SPIFFS. Each has a length of 100 lines. This is determined by the LOG_FILE_MAX_ROWS definition. This limits the logging to a total of 300 messages with the purpose of preventing Flash from becoming completely full if the program runs for a very long time. When all three files are full, the logger starts again with the first file and overwrites it.

EspLogger

These class implements the functionality described above.

The class is implemented as singelton. Therefore the normal way to get an object of the class is to call getInstance() and then a pointer to the object will be returned.

By calling logBegin(log_level, log_output_level) the logger is initialized and the logged messages from the last programm call is depending on the log_output_level printed to the serial monitor. The parameters log_level and log_output_level are stored in the configuration file and can be accessed using the Esp_Config class.

In your code you can call on of the following functions to log a message with a specific log level.

  • logFatal(message);
  • logError(message);
  • logWarning(message);
  • logInfo(message);
  • logDebug(message);

Note

The logger automatically adds an appropriate label and timestamp to your message. This means that you only have to worry about the content of the message and the logger takes care of the rest.

The class uses the EspSpiffs to access SPIFFS and the Ntp class to get the current time.

Last update: 2022-02-13
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