Concurrent Abstract Predicates – long version – ( Draft , submitted for publication )

Abstraction is key to understanding and reasoning about large computer systems. Abstraction is easy to achieve if the relevant data structures are disjoint, but rather difficult when they are partially shared, as is the case for concurrent modules. We present a program logic for reasoning abstractly about data structures that gives us a fiction of disjointness and permits compositional reasoning. The internal details of a module are completely hidden from the client by concurrent abstract predicates. We reason about a module’s implementation using separation logic with permissions, and provide abstract specifications for use by client programs using concurrent abstract predicates. We illustrate our abstract reasoning by building two implementations of a lock module on top of hardware instructions, and two implementations of a concurrent set module on top of the lock module.