add logging utility features

[quoeamaster]

logging is essential to all kinds of systems, a simple yet flexible logging architecture could solve things out in an efficient way.

Features involved:

• able to add logger(s) to the system; each logger would help to log down messages in a particular scenario (e.g. rolling-file logging, rdbms logging, console logging)
• provide lifecycle hooks / apis to add necessary resource claiming and resource release operations

[quoeamaster]

implementation =>

• ILogger interface = interface wrapping the functionalities of a logger

  • Write method to write out a message to a particular destionation
  • Name method returning the logger's name; use this name during the FlexLogger.WriteWithOptions() to indicate which logger implementation should be employed
  • Release method to release resources

• FlexLogger struct = the logger object for performing logging operations;

  • AddLogger method is provided to add new ILogger interface implementation
  • Write method is provided for message logging (also acting as a Writer interface)
  • WriteWithOptions indicating which logger should be employed for the logging operation

    logger = queutil.NewFlexLogger()
    // added 2 loggers
    logger.AddLogger(queutil.NewRollingFileLogger(logFilepath, 1, 2, 2, true))
    logger.AddLogger(queutil.NewConsoleLogger())

    ...
    // basic write
    iWrote, err := logger.Write([]byte(message + "\n"))
    if err != nil {
        return err
    }
    fmt.Printf("success in logging, wrote '%v' bytes of data\n", iWrote)

    ... writeWithOptions
    optionMap := make(map[string]bool)
    optionMap["consoleLogger"] = true
    optionMap["rollingFileLogger"] = true
    _, err = loggerWithOptions.WriteWithOptions([]byte(message + "\n"), optionMap)

[quoeamaster]

feature released at v0.1.1