This follows rather closely how rotation currently works in
rotate-logs.bro. logging.bro now defines:
# Default rotation interval; zero disables rotation.
const default_rotation_interval = 0secs &redef;
# Default naming suffix format.
const default_rotation_date_format = "%y-%m-%d_%H.%M.%S" &redef;
# Default postprocessor for writers outputting into files.
const default_rotation_postprocessor = "" &redef;
# Default function to construct the name of the rotated file.
# The default implementation includes
# default_rotation_date_format into the file name.
global default_rotation_path_func: function(info: RotationInfo) : string &redef;
Writer support for rotation is optional, usually it will only make
sense for file-based writers.
TODO: Currently, there's no way to customize rotation on a per file
basis, there are only the global defaults as described above.
Individual customization is coming next.
