def get_candidates(rules)
      candidates = []
      rules.each { |rule| candidates << rule if rule.ever_matched? && rule.time_to_report? }
      candidates
    end
def get_candidates(rules)
      candidates = []
      rules.each { |rule| candidates << rule if rule.ever_matched? && rule.time_to_report? }
      candidates
    end
Don't report a rule statistics if any of the conditions is met:
 1. The report time hasn't come(some rules might have larger report intervals).
 2. The rule is never matched.