Ada concurrent complexity metrics based on rendezvous relations

The most important factors influencing complexity of a concurrent program are communicating and synchronizing behaviours between tasks. In Ada program, these behaviours are expressed as rendezvous and relations between rendezvous. This paper investigates rendezvous successive and nesting relations, introduces the successive graph for successive relation and nesting tree for nesting relation, and gives the methods for constructing the graphs and trees. Some properties of the graph and the tree are given. Finally, the paper proposes that the concurrent complexity of a program is a weighted sum of the rendezvous successive complexity and nesting complexity and in turn, they are the sum of edge numbers of rendezvous successive graphs and sum of weighted node numbers on rendezvous nesting trees respectively