Software maintenance and the understanding of where in the source code features are implemented are two strongly coupled tasks that make up a large portion of the effort spent on developing applications. The concept of feature location investigated in this thesis can serve as a supporting factor in those tasks as it facilitates the automation of otherwise manual searches for source code artifacts. Challenges in this subject area include the aggregation and composition of a training corpus from historical codebase data for models as well as the integration and optimization of qualified topic modeling techniques. Building up on previous research, this thesis provides a comparison of two different techniques and introduces a toolkit that can be used to reproduce and extend on the results discussed. Specifically, in this thesis a changeset-based approach to feature location is pursued and applied to a large open-source Java project. The project is used to optimize and evaluate the performance of Latent Dirichlet Allocation models and Pachinko Allocation models, as well as to compare the accuracy of the two models with each other. As discussed at the end of the thesis, the results do not indicate a clear favorite between the models. Instead, the outcome of the comparison depends on the metric and viewpoint from which it is assessed.

No description available.

No description available.

La révision du code est un procédé essentiel quelque soit la maturité d'un projet; elle cherche à évaluer la contribution apportée par le code soumis par les développeurs. En principe, la révision du code améliore la qualité des changements de code (patches) avant qu'ils ne soient validés dans le repertoire maître du projet. En pratique, l'exécution de ce procédé n'exclu pas la possibilité que certains bugs passent inaperçus. Dans ce document, nous présentons une étude empirique enquétant la révision du code d'un grand projet open source. Nous investissons les relations entre les inspections des reviewers et les facteurs, sur les plans personnel et temporel, qui pourraient affecter la qualité de telles inspections.Premiérement, nous relatons une étude quantitative dans laquelle nous utilisons l'algorithme SSZ pour détecter les modifications et les changements de code favorisant la création de bogues (bug-inducing changes) que nous avons lié avec l'information contenue dans les révisions de code (code review information) extraites du systéme de traçage des erreurs (issue tracking system). Nous avons découvert que les raisons pour lesquelles les réviseurs manquent certains bogues était corrélées autant à leurs caractéristiques personnelles qu'aux propriétés techniques des corrections en cours de revue. Ensuite, nous relatons une étude qualitative invitant les développeurs de chez Mozilla à nous donner leur opinion concernant les attributs favorables à la bonne formulation d'une révision de code. Les résultats de notre sondage suggèrent que les développeurs considèrent les aspects techniques (taille de la correction, nombre de chunks et de modules) autant que les caractéristiques personnelles (l'expérience et review queue) comme des facteurs influant fortement la qualité des revues de code. / Code review is an essential element of any mature software development project; it aims at evaluating code contributions submitted by developers. In principle, code review should improve the quality of code changes (patches) before they are committed to the project's master repository. In practice, the execution of this process can allow bugs to get in unnoticed. In this thesis, we present an empirical study investigating code review of a large open source project. We explore the relationship between reviewers'code inspections and personal, temporal and participation factors that might affect the quality of such inspections. We first report a quantitative study in which we applied the SZZ algorithm to detect bug-inducing changes that were then linked to the code review information extracted from the issue tracking system. We found that the reasons why reviewers miss bugs are related to both their personal characteristics, as well as the technical properties of the patches under review. We then report a qualitative study that aims at soliciting opinions from Mozilla developers on their perception of the attributes associated with a well-done code review. The results of our survey suggest that developers find both technical (patch size, number of chunks, and module) and personal factors (reviewer's experience and review queue) to be strong contributors to the review quality.

Degradação do design é um problema central investigado na área de evolução de software. A densa rede de interdependências que emerge entre classes e módulos ao longo do tempo resulta em código difícil de mudar, não reutilizável e que não comunica por si só sua intenção. Dentre outros motivos, designs degradam porque requisitos mudam de maneiras não antecipadas pelo design inicial, ou seja, as modificações no código introduzem dependências novas e não planejadas entre classes e módulos do sistema. A gerência de dependências visa reduzir a degradação do design por meio de uma série de mecanismos que auxiliam na administração da complexidade estrutural inerente de sistemas orientados a objetos. Neste trabalho, investigamos as técnicas de identificação de dependências estruturais e lógicas. Em particular, por meio de um estudo de larga escala, comparamos os conjuntos desses dois tipos de dependências. Em seguida, conduzimos um estudo de caso a fim de identificar as origens de dependências lógicas. Por fim, fazemos um levantamento das técnicas de visualização de dependências e mostramos a ferramenta XFlow. / Design degradation is a central problem investigated in the area of software evolution. The dense web of interdependencies that emerges among classes and modules over time results in code that is hard to change, not reusable and that does not communicate its intention. Among other reasons, designs degrade because requirements changes in ways that were not anticipated by the initial design, i.e. the changes in code introduce new and unplanned dependencies among classes and modules of the system. Dependency management aims to reduce design degradation by means of a series of mechanisms that helps in the management of the inherent structural complexity of object oriented systems. In this work, we investigate structural and logical dependencies identification techniques. In particular, by means of a large scale study, we compare the sets of these two kinds of dependencies. Afterwards, we conduct a case study in order to uncover the origins of logical dependencies. Finally, we survey dependency visualization techniques and present the XFlow tool.

The demand for speeding up software development inside corporations triggers a series of issues related to coding organization. Software development teams have to achieve business deadlines, so they adopt the bad practice to copy-and-paste code. In this way, clones populate software repositories and hinder the improvement or maintenance of systems. Programming languages with object-oriented paradigm characteristics tend to make easy coding abstraction and reuse processes. However, a question arises: the same team working with several kinds of programming languages are influenced by their paradigms regarding the decrease of cloning incidence? This work proposed an approach to identify, analyze and compare clones inside heterogeneous software repositories without consider the development team profile. The experimental evaluation of the approach was possible thru two controlled experiments which aimed to detect and evaluate clones, using and adapting tools available on market. This evaluation was executed inside an organizational environment, which owned several applications with closed-source code but available to analysis. The final results showed no relationship to the amount of application code lines. Procedural language systems had a lower clone incidence and, when conflicting open and closed source systems, both had similar results regarding to the manifestation of source-code clones. / A exigência por acelerar o desenvolvimento de software nas empresas desencadeia uma série de problemas relacionados à organização do código. As equipes de desenvolvimento, pressionadas a cumprir prazos ditados pela área de negócio, adotam a prática ruim de copiar e colar código. Assim, os clones são criados e povoam os repositórios de software dessas companhias, tornando o aprimoramento e manutenção dos sistemas cada vez mais dificultado. Linguagens de programação que possuem características do paradigma de orientação a objetos tendem a facilitar ainda mais o processo de abstração de código e de reaproveitamento. No entanto, uma questão pode ser feita: uma mesma equipe, trabalhando com diversos tipos de linguagens, sofre influência destes tipos, no que diz respeito à diminuição da incidência de clones? Este trabalho propôs uma abordagem para identificar, analisar e comparar clones em repositórios heterogêneos de software, com uma análise tênue do perfil da equipe envolvida. A avaliação experimental da abordagem foi realizada por meio de dois experimentos controlados, os quais visaram a detecção e a avaliação de clones, utilizando e adaptando o ferramental disponível no mercado. Esta avaliação foi executada in-vivo, em um ambiente organizacional real, o qual possuía uma grande quantidade de aplicações e linhas de código fechado disponíveis para análise. Os resultados finais não apresentaram relação direta com a quantidade de linhas de código das aplicações. Sistemas de linguagem procedural apresentaram menor incidência de clones e, no conflito entre sistemas de código aberto e fechado, ambos tiveram resultados similares no que diz respeito à manifestação de clones de código-fonte.

Degradação do design é um problema central investigado na área de evolução de software. A densa rede de interdependências que emerge entre classes e módulos ao longo do tempo resulta em código difícil de mudar, não reutilizável e que não comunica por si só sua intenção. Dentre outros motivos, designs degradam porque requisitos mudam de maneiras não antecipadas pelo design inicial, ou seja, as modificações no código introduzem dependências novas e não planejadas entre classes e módulos do sistema. A gerência de dependências visa reduzir a degradação do design por meio de uma série de mecanismos que auxiliam na administração da complexidade estrutural inerente de sistemas orientados a objetos. Neste trabalho, investigamos as técnicas de identificação de dependências estruturais e lógicas. Em particular, por meio de um estudo de larga escala, comparamos os conjuntos desses dois tipos de dependências. Em seguida, conduzimos um estudo de caso a fim de identificar as origens de dependências lógicas. Por fim, fazemos um levantamento das técnicas de visualização de dependências e mostramos a ferramenta XFlow. / Design degradation is a central problem investigated in the area of software evolution. The dense web of interdependencies that emerges among classes and modules over time results in code that is hard to change, not reusable and that does not communicate its intention. Among other reasons, designs degrade because requirements changes in ways that were not anticipated by the initial design, i.e. the changes in code introduce new and unplanned dependencies among classes and modules of the system. Dependency management aims to reduce design degradation by means of a series of mechanisms that helps in the management of the inherent structural complexity of object oriented systems. In this work, we investigate structural and logical dependencies identification techniques. In particular, by means of a large scale study, we compare the sets of these two kinds of dependencies. Afterwards, we conduct a case study in order to uncover the origins of logical dependencies. Finally, we survey dependency visualization techniques and present the XFlow tool.