Writes log messages to a file. By default all logs are created in the dedicated logs folder in the framework root folder. This path can be changed when the writer is instantiated. Only a single file writer may write to a log file at any one time, but you can have multiple file writers pointing to different locations.
Log files are appended to and writes try to use an exclusive lock. This will work reasonably well on single server machines, however if you wish to log the output from multiple web-servers to the same master log, there may be concurrency issues and you should consider using the systemLogWriterDb writer instead.
protected formatMessage($inMessage, $inSource)
Applies some generic formatting to the message
Checks that the logFile Base Path exists in the file to be written