A Polymorphic Future and First-class Function Type for Concurrent Object-Oriented Programming

A "future" is a typed synchronization mechanism used to represent a value that will come into existence at some point in time after the creation of the future. In this paper, a polymorphic future type is introduced that differs from previous mechanisms in that it provides a first-class, extensible facility for expressing synchronized access to the typed result value of a concurrent computation. The proposed mechanism requires write-once/read-many synchronization, which is implemented in terms of common thread synchronization primitives, thereby ensuring a high-degree of efficiency. The type definition and type specialization features of C++ are used to illustrate how one would implement a polymorphic future type in a strongly typed object-oriented language supporting polymorphic type definitions. 1 Introduction Applications increasily employ multiple threads of control due to the utility of the thread mechanism and its widening availability. The utility of threads is apparent in any a..