Comprehending annotations on object-oriented programs using fractional permissions

Fractional permissions are a general system for managing access to mutable state. We show how fractional permis-sions can give semantics to a regimen of annotations includ-ing“unique,”“non-null,”“read-only,”ownership, and method effects. The unification supports new annotations: “unique-write ” and “from”. We also develop a model of object in-variants in the presence of inheritance using “nesting, ” an extension of “adoption.” 1

On the Effectiveness of Contracts as Test Oracles in the Detection and Diagnosis of Faults in Concurrent Object-Oriented Software

Design by Contract (DbC) is a software development methodology that focuses on clearly defining the interfaces between components to produce better quality object-oriented software. The idea behind DbC is that a method defines a contract stating the requirements a client needs to fulfill to use it, the precondition, and the properties it ensures after its execution, the postcondition. Though there exists ample support for DbC for sequential programs, applying DbC to concurrent programs presents several challenges. Using Java as the target programming language, this paper tackles such challenges by augmenting the Java Modelling Language (JML) and modifying the JML compiler to generate Runtime Assertion Checking (RAC) code to support DbC in concurrent programs. We applied our solution in a carefully designed case study on a highly concurrent industrial software system from the telecommunications domain to assess the effectiveness of contracts as test oracles in detecting and diagnosing functional faults in concurrent software. Based on these results, clear and objective requirements are defined for contracts to be effective test oracles for concurrent programs whilst balancing the effort to design them. Main results include that contracts of a realistic level of completeness and complexity can detect around 76% of faults and reduce the diagnosis effort for such faults by at least ten times. We, therefore, show that DbC can not only be applied to concurrent software but can also be a valua

Observations on the Assured Evolution of Concurrent Java Programs

Evolving and refactoring concurrent Java software can be error-prone, resulting in race conditions and other concurrency difficulties. We suggest that there are two principal causes: concurrency design intent is often not explicit in code and, additionally, consistency of intent and code cannot easily be established through either testing or inspection. We explore several aspects of this issue in this paper. First, we describe a tool-assisted approach to modeling and assurance for concurrent programs. Second, we give an account of recent case study experience on larger-scale production Java systems. Third, we suggest an approach to scalable co-evolution of code and models that is designed to support working programmers without special training or incentives. Fourth, we propose some concurrency-related refactorings that, with suitable analysis and tool support, can potentially offer assurances of soundness. Abstract © Elsevie