rational_choice

Makes a fuzzy logic choice based on a continuum of values. For when a "yes or no" is not-quite-good-enough.

Primary use is for things like load balancing. Imagine you have a server handling 14 connections, and you know that it can take about 20 maximum. When you decide whether to send the connection number 17 to it, you want to take a little margin and only send that connection sometimes, to balance the choices - so you want to use a softer bound (a bit of a fuzzy logic).

# ten connections is always safe
will_accept_connection = RationalChoice::Dimension.new(false_at_or_below: 20, true_at_or_above:10)
if will_accept_connection.choose(server.current_connection_count + 1) # will give you a fuzzy choice
  server.accept(new_client)
else
  ... # over capacity at the moment, try later
end

This way the return value of choose() will be determined by the probability of the value being true - i.e. how close it is to the upper bound. Values at or below the lower bound will always choose false. Values at or above the upper bound will always choose true.

Useful to give rational choices on multiple values, averaged together.

num_clients = Dimension.new(false_at_or_below: 200, true_at_or_above: 100)
bandwidth = Dimension.new(false_at_or_below:2048, true_at_or_above: 1024)
has_capacity = ManyDimensions.new(num_clients, bandwidth)

will_accept_connection = has_capacity.choose(current_client_count, current_bandwidth)

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