International Journal of applied mathematics and computer science

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Paper details

Number 1 - March 1997
Volume 7 - 1997

On-the-fly detection of a class of word-based patterns in labelled DAGs

Michel Hurfin, Michel Raynal

The problem tackled in this paper originates from the debugging of distributed applications. Execution of such an application can be modelled as a partially ordered set of process states. The debugging of control flows (sequences of process states) of these executions is based on satisfying the predicates by process states. A process state that satisfies a predicate inherits its label. In this context, it follows that a distributed execution is a labelled directed acyclic graph (DAG for brevity). To debug or to determine if control flows of a distributed execution satisfy some property amounts to testing if the labelled DAG includes some pattern defined on predicate labels. This paper first introduces a general pattern (called the diamond necklace) which includes classical patterns encountered in distributed debugging. Then an efficient polynomial-time algorithm detecting such patterns in a labelled DAG is presented. To be easily adapted to an on-the-fly detection of the pattern in distributed executions, the algorithm visits the nodes of the graph according to a topological sort strategy.