interactive_timeout.rb

class Current < ActiveSupport::CurrentAttributes
  attribute :interactive_timeout_remaining
end

class ApplicationController < ActionController::Base
  before_action :set_interactive_timeout_remaining

  def set_interactive_timeout_remaining
    Current.interactive_timeout_remaining = 5.seconds
  end
end

module InteractiveTimeout
  # Wrap API operations, yields remaining time if set.
  # WARNING: can be negative.
  def self.tracking
    if remaining = Current.interactive_timeout_remaining
      start = Time.current
    end
    yield(remaining)
  ensure
    if remaining
      duration = Time.current - start
      Current.interactive_timeout_remaining -= duration
    end
  end
end

class SomeApi
  def execute
    InteractiveTimeout.tracking do |timeout|
      faraday_connection.timeout(timeout || 30.seconds).get
    end
  end
end