Distributed snapshots for ad hoc network systems

Abstract

Snapshot algorithms are fundamental algorithms in recording consistent global states of a distributed system. They find a large class of important applications such as monitoring and debugging of distributed systems and detection of stable properties (e.g. deadlock, termination and loss of tokens). Unfortunately, most existing snapshot algorithms were designed for static network systems and cellular systems only. They cannot be applied directly in recent emerging ad hoc network systems, which usually have no fixed infrastructure and may experience dynamic topology changes in the mid of execution. This paper presents a snapshot algorithm that can work in an ad hoc network system. Compared to the traditional snapshot algorithms, the proposed algorithm can guarantee both the causal consistency and the topological consistency. Simple methods are also discussed to reduce logged system states and exchanged message timestamps when applying the algorithm.