Property-Based Testing - The ProTest Project

The ProTest project is an FP7 STREP on property based testing. The purpose of the project is to develop software engineering approaches to improve reliability of service-oriented networks; support fault-finding and diagnosis based on specified properties of the system. And to do so we will build automated tools that will generate and run tests, monitor execution at run-time, and log events for analysis. The Erlang / Open Telecom Platform has been chosen as our initial implementation vehicle due to its robustness and reliability within the telecoms sector. It is noted for its success in the ATM telecoms switches by Ericsson, one of the project partners, as well as for multiple other uses such as in facebook, yahoo etc. In this paper we provide an overview of the project goals, as well as detailing initial progress in developing property based testing techniques and tools for the concurrent functional programming language Erlang

Clone Detection and Elimination for Haskell

Duplicated code is a well known problem in software maintenance and refactoring. Code clones tend to increase program size and several studies have shown that duplicated code makes maintenance and code understanding more complex and time consuming. This paper presents a new technique for the detection and removal of duplicated Haskell code. The system is implemented within the refactoring framework of the Haskell Refactorer (HaRe), and uses an Abstract Syntax Tree (AST) based approach. Detection of duplicate code is automatic, while elimination is semi-automatic, with the user managing the clone removal. After presenting the system, an example is given to show how it works in practice

Program analysis for code duplication in logic programs

In this PhD project, we deal with the issue of code duplication in logic programs. In particular semantical duplication or redundancy is generally viewed as a possible seed of inconvenience in all phases of the program lifecycle, from development to maintenance. The core of this research is the elaboration of a theory of semantical duplication, and of an automated program analysis capable of detecting such duplication and which could steer, to some extent, automatic refactoring of program code

The pragmatics of clone detection and elimination

The occurrence of similar code, or ‘code clones’, can make program code difficult to read, modify and maintain. This paper describes industrial case studies of clone detection and elimination, and were were performed in collaboration with engineers from Ericsson AB using the refactoring and clone detection tool Wrangler for Erlang. We use the studies to illustrate the complex set of decisions that have to be taken when performing clone elimination in practice; we also discuss how the studies have informed the design of the tool. However, the conclusions we draw are largely language-independent, and set out the pragmatics of clone detection and elimination in real-world projects as well as design principles for clone detection decision-support tools. Context. The context of this work is the fact that a software tool is designed to be used; the success of such a tool therefore depends on its suitability and usability in practice. The work proceeds by observing the use of a tool in particular case studies in detail, through a “partici- pant observer” approach, and drawing qualitative conclusions from these studies, rather than collecting and analysing quantitative data from a larger set of applications. Our conclusions help not only programmers but also the designers of software tools. Inquiry. Data collected in this way make two kinds of contribution. First, they provide the basis for deriving a set of questions that typically need to be answered by engineers in the process of removing clones from an application, and a set of heuristics that can be used to help answer these questions. Secondly, they provide feedback on existing features of software tools, as well as suggesting new features to be added to the tools. Approach. The work was undertaken by the tool designers and engineers from Ericsson AB, working to- gether on clone elimination for code from the company. Knowledge. The work led to a number of conclusions, at different levels of generality. At the top level, there is overwhelming evidence that the process of clone elimination cannot be entirely automated, and needs to include the input of engineers familiar with the domain in question. Furthermore, there is strong evidence that the automated tools are sensitive to a set of parameters, which will differ for different applications and programming styles, and that individual clones can be over- and under-identified: again, involving those with knowledge of the code and the domain is key to successful application. Grounding. The work is grounded in “participant observation” by the tool builders, who made detailed logs of the processes undertaken by the group. Importance. The work gives guidelines that assist an engineer in using clone detection and elimination in practice, as well as helping a tool developer to shape their tool building. Although the work was in the context of a particular tool and programming language, the authors would argue that the high-level knowledge gained applies equally well to other notions of clone, as well as other tools and programming languages

Set-theoretic Types for Erlang

Erlang is a functional programming language with dynamic typing. The language offers great flexibility for destructing values through pattern matching and dynamic type tests. Erlang also comes with a type language supporting parametric polymorphism, equi-recursive types, as well as union and a limited form of intersection types. However, type signatures only serve as documentation, there is no check that a function body conforms to its signature. Set-theoretic types and semantic subtyping fit Erlang's feature set very well. They allow expressing nearly all constructs of its type language and provide means for statically checking type signatures. This article brings set-theoretic types to Erlang and demonstrates how existing Erlang code can be statically typechecked without or with only minor modifications to the code. Further, the article formalizes the main ingredients of the type system in a small core calculus, reports on an implementation of the system, and compares it with other static typecheckers for Erlang.Comment: 14 pages, 9 figures, IFL 2022; latexmk -pdf to buil

Refactoring for introducing and tuning parallelism for heterogeneous multicore machines in Erlang

This research has been generously supported by the European Union Framework 7 Para-Phrase project (IST-288570), EU Horizon 2020 projects RePhrase (H2020-ICT-2014-1), agreement number 644235; Teamplay (H2020-ICT 2017-1) agreement number 779882, and EPSRC Discovery, EP/P020631/1. EU COST Action IC1202: Timing Analysis On Code-Level (TACLe), and by a travel grant from EU HiPEAC.This paper presents semi‐automatic software refactorings to introduce and tune structured parallelism in sequential Erlang code, as well as to generate code for running computations on GPUs and possibly other accelerators. Our refactorings are based on the lapedo framework for programming heterogeneous multi‐core systems in Erlang. lapedo is based on the PaRTE refactoring tool and also contains (1) a set of hybrid skeletons that target both CPU and GPU processors, (2) novel refactorings for introducing and tuning parallelism, and (3) a tool to generate the GPU offloading and scheduling code in Erlang, which is used as a component of hybrid skeletons. We demonstrate, on four realistic use‐case applications, that we are able to refactor sequential code and produce heterogeneous parallel versions that can achieve significant and scalable speedups of up to 220 over the original sequential Erlang program on a 24‐core machine with a GPU.PostprintPeer reviewe

Restoration of legacy parallelism in C and C++ applications

Parallel patterns are a high-level programming paradigm that enables non-experts in parallelism to develop structured parallel programs that are maintainable, adaptive, and portable whilst achieving good performance on a variety of parallel systems. However, there still exists a large base of legacy-parallel code developed using ad-hoc methods and incorporating low-level parallel/concurrency libraries such as pthreads without any parallel patterns in the fundamental design. This code would benefit from being restructured and rewritten into pattern-based code. However, the process of rewriting the code is laborious and error-prone, due to typical concurrency and pthreading code being closely intertwined throughout the business logic of the program. In this paper, we present a new software restoration methodology, to transform legacy-parallel programs implemented using e.g. pthreads into structured patterned equivalents. We demonstrate our restoration technique on a number of benchmarks, allowing the introduction of patterned parallelism in the resulting code; we record improvements in cyclomatic complexity and speedups.PostprintPeer reviewe

Restoration of legacy parallelism : transforming pthreads into farm and pipeline patterns

Funding: This work was generously supported by the EU Horizon 2020 project, TeamPlay (https://www.teamplay-h2020.eu), grant number 779882, and UK EPSRC Discovery, grant number EP/P020631/1.Parallel patterns are a high-level programming paradigm that enables non-experts in parallelism to develop structured parallel programs that are maintainable, adaptive, and portable whilst achieving good performance on a variety of parallel systems. However, there still exists a large base of legacy-parallel code developed using ad-hoc methods and incorporating low-level parallel/concurrency libraries such as pthreads without any parallel patterns in the fundamental design. This code would benefit from being restructured and rewritten into pattern-based code. However, the process of rewriting the code is laborious and error-prone, due to typical concurrency and pthreading code being closely intertwined throughout the business logic of the program. In this paper, we present a new software restoration methodology, to transform legacy-parallel programs implemented using pthreads into structured farm and pipeline patterned equivalents. We demonstrate our restoration technique on a number of benchmarks, allowing the introduction of patterned farm and pipeline parallelism in the resulting code; we record improvements in cyclomatic complexity and speedups on a number of representative benchmarks.Publisher PDFPeer reviewe