Automatic Addition of Fault-Tolerance in the Presense of Unchangeable Environment Actions TLE

Mohammad Roohitavaf and Sandeep S. Kulkarni


We focus on the problem of adding fault-tolerance to an existing concurrent protocol in  the presence of unchangeable environment actions. Such unchangeable actions occur in cases  where a subset of components/processes cannot be modified since they represent third-party  components or are constrained by physical laws. These actions differ from faults in that they are  (1) simultaneously collaborative and disruptive, (2) essential for satisfying the specification, and (3)  possibly non-terminating. Hence, if these actions are modeled as faults while adding fault-tolerance,  it causes existing model repair algorithms to declare failure to add fault-tolerance. We present a set of algorithms for adding stabilization and fault-tolerance for programs that run in presence of environment actions. We prove the soundness, completeness, and the complexity of our algorithms.  We have implemented all of our algorithms using symbolic techniques in Java. The experimental results of our algorithms for various examples are also provided.


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