ChangeBeadsThreader: An Interactive Environment for Tailoring Automatically Untangled Changes

To improve the usability of a revision history, change untangling, which reconstructs the history to ensure that changes in each commit belong to one intentional task, is important. Although there are several untangling approaches based on the clustering of fine-grained editing operations of source code, they often produce unsuitable result for a developer, and manual tailoring of the result is necessary. In this paper, we propose ChangeBeadsThreader (CBT), an interactive environment for splitting and merging change clusters to support the manual tailoring of untangled changes. CBT provides two features: 1) a two-dimensional space where fine-grained change history is visualized to help users find the clusters to be merged and 2) an augmented diff view that enables users to confirm the consistency of the changes in a specific cluster for finding those to be split. These features allow users to easily tailor automatically untangled changes.Comment: 5 pages, SANER 202

Human-Centric Tools for Navigating Code

All software failures are fundamentally the fault of humansthe software\u27s design was flawed. The high cost of such failures ultimately results in developers having to design, implement, and test fixes, which all take considerable time and effort, and may result in more failures. As developers work on software maintenance tasks, they must navigate enormous codebases that may comprise millions of lines of code organized across thousands of modules. However, navigating code carries with it a plethora of problems for developers. In the hopes of addressing these navigation barriers, modern code editor and development environments provide a variety of features to aid in navigation; however, they are not without their limitations. Code navigations take many forms, and in this work I focus on three key types of code navigation in modern software development: navigating the working set, navigating among versions of code, and navigating the code structure. To address the challenges of navigating code, I designed three novel software development tools, one to enhance each type of navigation. First, I designed and implemented Patchworks, a code editor interface to support developers in navigating the working set. Patchworks aims to make these more efficient by providing a fixed grid of open code fragments that developers can quickly navigate. Second, I designed and implemented Yestercode, a code editor extension to support navigating among versions of code. Yestercode does so by providing a comparison view of the current code and a previous version of the same code. Third, I designed and implemented Wandercode, a code editor extension to enable developers to efficiently navigate the structure of their code. Wandercode aims to do so by providing a visualization of the code\u27s call graph overlayed on the code editor. My approach to designing these tools for more efficient code navigation was a human-centric onethat is, based on the needs of actual developers performing real software development tasks. Through user study evaluations, I found that these tools significantly improved developer productivity by reducing developers\u27 time spent navigating and mental effort during software maintenance tasks

Representing Program Edits with the Choice Calculus

The problem of supporting more advanced selective undo operations has received a lot of attention. However, selective undo is generally missing in commonly used editors. Moreover, partial selective undo, the ability of undoing just part of some edit so that other edits may be undone, is not supported at all. We observe that a fundamental obstacle is the lack of a more flexible and compositional edit model. This project addresses this issue and proposes the choice edit model, which is based on the representation provided by the choice calculus. The central idea is to represent an edit through a choice that contains the old and the new code as alternatives. Edits inherit properties from choices and can thus be composed, nested, and transformed so that dependent edits may be untangled and undone partially. The choice representation is an internal representation, not meant to be exposed to programmers directly. To communicate the structure and dependencies of edits we introduce program edit graphs as an alternative, more abstract representation. Program edit graphs explicitly represent program variants and their relations. We also discuss the scalability of PEGs

Design and Implementation of a Conceptual Modeling Assistant (CMA)

This Master's Thesis de nes an architecture for a Conceptual Modeling Assistant (CMA) along with an implementation of a running prototype. Our CMA is a piece of software that runs on top of current modeling tools whose purpose is to collaborate with the conceptual modelers while developing a conceptual schema. The main functions of our CMA are to actively criticize the state of a conceptual schema, to suggest actions to do in order to improve the conceptual schema, and to o er new operations to automatize building a schema. On the one hand, the presented architecture assumes that the CMA has to be adapted to a modeling tool. Thus, the CMA permits the inclusion of new features, such as the detection of new defects to be criticized and new operations a modeler can execute, in a modeling tool. As a result, all modeling tools to which the CMA is adapted bene t of all these features without further work. On the other hand, the construction of our prototype involves three steps: the de nition of a simple, custom modeling tool; the implementation of the CMA; and the adaptation of the CMA to the custom modeling tool. Furthermore, we also present and implement some examples of new features that can be added to the CMA

AspectMaps: Extending Moose to visualize AOP software

International audienceWhen using aspect-oriented programming the application implicitly invokes the functionality contained in the aspects. Consequently program comprehension of such a software is more intricate. To alleviate this difficulty we developed the AspectMaps visualization and tool. AspectMaps extends the Moose program comprehension and reverse engineering platform with support for aspects, and is implemented using facilities provided by Moose. In this paper we present the AspectMaps tool, and show how it can be used by performing an exploration of a fairly large aspect-oriented application. We then show how we extended the FAMIX meta-model family that underpins Moose to also provide support for aspects. This extension is called ASPIX, and thanks to this enhancement Moose can now also treat aspect-oriented software. Finally, we report on our experiences using some of the tools in Moose; Mondrian to implement the visualization, and Glamour to build the user interface. We discuss how we were able to implement a sizable visualization tool using them and how we were able to deal with some of their limitations. Note: This paper uses colors extensively. Please use a color version to better understand the ideas presented here

Improving Software Quality by Synergizing Effective Code Inspection and Regression Testing

Software quality assurance is an essential practice in software development and maintenance. Evolving software systems consistently and safely is challenging. All changes to a system must be comprehensively tested and inspected to gain confidence that the modified system behaves as intended. To detect software defects, developers often conduct quality assurance activities, such as regression testing and code review, after implementing or changing required functionalities. They commonly evaluate a program based on two complementary techniques: dynamic program analysis and static program analysis. Using an automated testing framework, developers typically discover program faults by observing program execution with test cases that encode required program behavior as well as represent defects. Unlike dynamic analysis, developers make sure of the program correctness without executing a program by static analysis. They understand source code through manual inspection or identify potential program faults with an automated tool for statically analyzing a program. By removing the boundaries between static and dynamic analysis, complementary strengths and weaknesses of both techniques can create unified analyses. For example, dynamic analysis is efficient and precise but it requires selection of test cases without guarantee that the test cases cover all possible program executions, and static analysis is conservative and sound but it produces less precise results due to its approximation of all possible behaviors that may perform at run time. Many dynamic and static techniques have been proposed, but testing a program involves substantial cost and risks and inspecting code change is tedious and error-prone. Our research addresses two fundamental problems in dynamic and static techniques. (1) To evaluate a program, developers are typically required to implement test cases and reuse them. As they develop more test cases for verifying new implementations, the execution cost of test cases increases accordingly. After every modification, they periodically conduct regression test to see whether the program executes without introducing new faults in the presence of program evolution. To reduce the time required to perform regression testing, developers should select an appropriate subset of the test suite with a guarantee of revealing faults as running entire test cases. Such regression testing selection techniques are still challenging as these methods also have substantial costs and risks and discard test cases that could detect faults. (2) As a less formal and more lightweight method than running a test suite, developers often conduct code reviews based on tool support; however, understanding context and changes is the key challenge of code reviews. While reviewing code changes—addressing one single issue—might not be difficult, it is extremely difficult to understand complex changes—including multiple issues such as bug fixes, refactorings, and new feature additions. Developers need to understand intermingled changes addressing multiple development issues, finding which region of the code changes deals with a particular issue. Although such changes do not cause trouble in implementation, investigating these changes becomes time-consuming and error-prone since the intertwined changes are loosely related, leading to difficulty in code reviews. To address the limitations outlined above, our research makes the following contributions. First, we present a model-based approach to efficiently build a regression test suite that facilitates Extended Finite State Machines (EFSMs). Changes to the system are performed at transition level by adding, deleting or replacing transition. Tests are a sequence of input and expected output messages with concrete parameter values over the supported data types. Fully-observable tests are introduced whose descriptions contain all the information about the transitions executed by the tests. An invariant characterizing fully observable tests is formulated such that a test is fully-observable whenever the invariant is a satisfiable formula. Incremental procedures are developed to efficiently evaluate the invariant and to select tests from a test suite that are guaranteed to exercise a given change when the tests run on a modified EFSM. Tests rendered unusable due to a change are also identified. Overlaps among the test descriptions are exploited to extend the approach to simultaneously select and discard multiple tests to alleviate the test selection costs. Although test regression selection problem is NP-hard [78], the experimental results show the cost of our test selection procedure is still acceptable and economical. Second, to support code review and regression testing, we present a technique, called ChgCutter. It helps developers understand and validate composite changes as follows. It interactively decomposes these complex, composite changes into atomic changes, builds related change subsets using program dependence relationships without syntactic violation, and safely selects only related test cases from the test suite to reduce the time to conduct regression testing. When a code reviewer selects a change region from both original and changed versions of a program, ChgCutter automatically identifies similar change regions based on the dependence analysis and the tree-based code search technique. By automatically applying a change to the identified regions in an original program version, ChgCutter generates a program version which is a syntactically correct version of program. Given a generated program version, it leverages a testing selection technique to select and run a subset of the test suite affected by a change automatically separated from mixed changes. Based on the iterative change selection process, there can be each different program version that include its separated change. Therefore, ChgCutter helps code reviewers inspect large, complex changes by effectively focusing on decomposed change subsets. In addition to assisting understanding a substantial change, the regression testing selection technique effectively discovers defects by validating each program version that contains a separated change subset. In the evaluation, ChgCutter analyzes 28 composite changes in four open source projects. It identifies related change subsets with 95.7% accuracy, and it selects test cases affected by these changes with 89.0% accuracy. Our results show that ChgCutter should help developers effectively inspect changes and validate modified applications during development

Memory Subsystems for Security, Consistency, and Scalability

In response to the continuous demand for the ability to process ever larger datasets, as well as discoveries in next-generation memory technologies, researchers have been vigorously studying memory-driven computing architectures that shall allow data-intensive applications to access enormous amounts of pooled non-volatile memory. As applications continue to interact with increasing amounts of components and datasets, existing systems struggle to eÿciently enforce the principle of least privilege for security. While non-volatile memory can retain data even after a power loss and allow for large main memory capacity, programmers have to bear the burdens of maintaining the consistency of program memory for fault tolerance as well as handling huge datasets with traditional yet expensive memory management interfaces for scalability. Today’s computer systems have become too sophisticated for existing memory subsystems to handle many design requirements. In this dissertation, we introduce three memory subsystems to address challenges in terms of security, consistency, and scalability. Specifcally, we propose SMVs to provide threads with fne-grained control over access privileges for a partially shared address space for security, NVthreads to allow programmers to easily leverage nonvolatile memory with automatic persistence for consistency, and PetaMem to enable memory-centric applications to freely access memory beyond the traditional process boundary with support for memory isolation and crash recovery for security, consistency, and scalability

Experimental Object-Oriented Modelling

This thesis examines object-oriented modelling in experimental system development. Object-oriented modelling aims at representing concepts and phenomena of a problem domain in terms of classes and objects. Experimental system development seeks active experimentation in a system development project through, e.g., technical prototyping and active user involvement. We introduce and examine "experimental object-oriented modelling" as the intersection of these practices