Concurrency Combinators for Declarative Synchronization

Abstract

Abstract. Developing computer systems that are both concurrent and evolving is challenging. To guarantee consistent access to resources by concurrent software components, some synchronization is required. A synchronization logic, or policy, is at present entangled in the component code. Adding a new component or modifying existing components, which may require a change of the (global) synchronization policy, is therefore subjected to an extensive inspection of the complete code. We propose a calculus of concurrency combinators that allows a program code and its synchronization policy to be expressed separately; the policies include true parallelism, sequentiality, and isolation-only transactions. The calculus is equipped with an operational semantics and a type system. The type system is used to verify if a synchronization policy declared using combinators can be satisfied by program execution.

Advances in the Design and Implementation of Group Communication Middleware

“…Two approaches to such separation of concerns have been developed within our project: (1) static [24], in which synchronization policy (that may include isolation) is declared between components using concurrency combina-tors, and (2) dynamic [23], in which synchronization policy is declared between semantic rôles using abstract types. In [24], we defined a property, called composition safety, that informally means that any runtime execution of a protocol can satisfy the synchronization policy declared using the language of concurreny combinators. The main result of this work was to show that the property can be verified statically, thus eliminating runtime errors due to wrong composition.…”