Clarke, Dave Wrigstad, Tobias Östlund, Johan Johnsen, Einar Broch #
Lecture Notes in Computer Science vol:5356 pages:139-154
APLAS edition:6 location:Bangalore, India date:9-11 December 2008
Active objects offer a structured approach to concurrency, encapsulating both unshared state and a thread of control. For efficient data transfer, data should be passed by reference whenever possible, but this introduces aliasing and undermines the validity of the active objects. This paper proposes a minimal variant of ownership types that preserves the required race freedom invariant yet enables data transfer by reference between active objects (that is, without copying) in many cases, and a cheap clone operation where copying is necessary. Our approach is general and should be adaptable to several existing active object systems.