class ActiveRecord::ConnectionAdapters::ConnectionPool

  # drain all idle connections
  # if idle_time is specified only connections idle for N seconds will be drained
  def drain(idle_time=nil)
    synchronize do
      @available.clear
      @connections.delete_if do |conn|
        try_drain?(conn, idle_time)
      end

      @connections.each do |conn|
        @available.add conn if !conn.in_use?
      end
    end

  end

  private

  def try_drain?(conn, idle_time)
    if !conn.in_use?
      if !idle_time || conn.last_use < idle_time.seconds.ago
        conn.disconnect!
        return true
      end
    end

    false
  end

end