Implementing Safe Sharing Features for Encore

Abstract: Actor isolation is an important property in parallel and concurrent programs that utilize the actor model. However, when expressing certain patterns isolation can sometimes be too strong and forces complexity on actors. To address this problem, two new language constructs have been introduced: Bestow allows an actor to delegate a part of its interface to its internal objects; Atomic enables grouping of messages which requires them to be handled in sequence. This thesis discusses several valid designs which are compared in the context of an object-oriented and actor based language called Encore. Bestow and atomic have proven to simplify several patterns and to minimize the complexity of actors by decoupling classes and allowing for granular interfaces. This additional abstraction comes with some overhead at run-time which there is plenty of room for reducing in future work. Equipped with these new tools a programmer can simplify complex concurrency patterns, allowing them to focus on the main task at hand.