Escaping with Future Variables in HALO

Abstract

HALO is a novel aspect language introducing a logic-based pointcut language which combines history-based pointcuts and “escape” conditions for interacting with the base language. This combination is difficult to support when escape conditions access context exposed by “future” join points. This paper introduces a weaving mechanism based on copying objects for resolving such pointcuts. Though this seems a memory consuming solution, it can be easily combined with HALO’s analysis for reducing the join point history. Furthermore, pointcuts with escape conditions accessing future join point context, sometimes require less memory than pointcuts that don’t, but otherwise implement the same functionality. In this paper, we illustrate this by measuring memory usage for simulations of an e-commerce application, switching between an implementation where the pointcut definitions contain escape conditions referring to future join point context, and an equivalent implementation that doesn’t.