Safe runtime verification of real-time properties

Abstract

Introducing a monitor on a system typically changes the system’s behaviour by slowing the system down and increasing memory consumption. This may possibly result in creating new bugs, or possibly even ‘fixing’ bugs, only to reappear as the monitor is removed. Properties written in a real-time logic, such as duration calculus, can be particularly sensitive to such changes induced through monitoring. The same problem occurs in other scenarios such as when a system is ported to a faster machine. In this paper, we identify a class of real-time properties, in duration calculus, which are monotonic under the slowing down (speeding up) of the underlying system. We apply this approach to the real-time runtime monitoring tool Larva, where we use duration calculus as a monitoring property specification language, so we automatically identify properties which can be shown to be monotonic with respect to system re-timing.