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ACM SIGPLAN International conference on object-oriented programming, systems, languages, and applications (oopsla)

作者： Hague, Matthew Lin, Anthony W. Ong, C. -H. Luke Univ London London WC1E 7HU England Yale NUS Coll Singapore Singapore Univ Oxford Oxford OX1 2JD England

ISBN: (纸本)9781450336895

HTML5 applications normally have a large set of CSS (Cascading Style Sheets) rules for data display. Each CSS rule consists of a node selector and a declaration block (which assigns values to selected nodes' display attributes). As web applications evolve, maintaining CSS files can easily become problematic. Some CSS rules will be replaced by new ones, but these obsolete (hence redundant) CSS rules often remain in the applications. Not only does this "bloat" the applications increasing the bandwidth requirement but it also significantly increases web browsers' processing time. Most works on detecting redundant CSS rules in HTML5 applications do not consider the dynamic behaviors of HTML5 (specified in Java Script);in fact, the only proposed method that takes these into account is dynamic analysis, which cannot soundly prove redundancy of CSS rules. In this paper, we introduce an abstraction of HTML5 applications based on monotonic tree rewriting and study its "redundancy problem". We establish the precise complexity of the problem and various subproblems of practical importance (ranging from P to EXP). In particular, our algorithm relies on an efficient reduction to an analysis of symbolic pushdown systems (for which highly optimised solvers are available), which yields a fast method for checking redundancy in practice. We implemented our algorithm and demonstrated its efficacy in detecting redundant CSS rules in HTML5 applications.

关键词： HTML5 jQuery CSS redundancy analysis static analysis tree rewriting symbolic pushdown systems

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Hybrid STM/HTM for Nested Transactions on OpenJDK

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ACM SIGPLAN NOTICES 2016年第10期51卷 660-676页

作者： Chapman, Keith Hosking, Antony L. Moss, J. Eliot B. Purdue Univ W Lafayette IN 47907 USA Australian Natl Univ Data61 Canberra ACT Australia Univ Massachusetts Amherst MA USA

Transactional memory (TM) has long been advocated as a promising pathway to more automated concurrency control for scaling concurrent programs running on parallel hardware. Software TM (STM) has the benefit of being able to run general transactional programs, but at the significant cost of overheads imposed to log memory accesses, mediate access conflicts, and maintain other transaction metadata. Recently, hardware manufacturers have begun to offer commodity hardware TM (HTM) support in their processors wherein the transaction metadata is maintained "for free" in hardware. However, HTM approaches are only best-effort: they cannot successfully run all transactional programs, whether because of hardware capacity issues (causing large transactions to fail), or compatibility restrictions on the processor instructions permitted within hardware transactions (causing transactions that execute those instructions to fail). In such cases, programs must include failure-handling code to attempt the computation by some other software means, since retrying the transaction would be futile. Thus, a canonical use of HTM is lock elision: replacing lock regions with transactions, retrying some number of times in the case of conflicts, but falling back to locking when HTM fails for other reasons. Here, we describe how software and hardware schemes can combine seamlessly into a hybrid system in support of transactional programs, allowing use of low-cost HTM when it works, but reverting to STM when it doesn't. We describe heuristics used to make this choice dynamically and automatically, but allowing the transition back to HTM opportunistically. Our implementation is for an extension of Java having syntax for both open and closed nested transactions, and boosting, running on the OpenJDK, with dynamic injection of STM mechanisms (into code variants used under STM) and HTM instructions (into code variants used under HTM). Both schemes are compatible to allow different threads to run concur

关键词： transactional memory nested transactions hardware transactional memory software transactional memory Java Design Experimentation languages Measurement Performance

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Remote-Scope Promotion: Clarified, Rectified, and Verified 2015

Remote-Scope Promotion: Clarified, Rectified, and Verified

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ACM SIGPLAN International conference on object-oriented programming, systems, languages, and applications (oopsla)

作者： Wickerson, John Batty, Mark Beckmann, Bradford M. Donaldson, Alastair F. Univ London Imperial Coll Sci Technol & Med London SW7 2AZ England Univ Kent Canterbury CT2 7NZ Kent England Adv Micro Devices Inc Sunnyvale CA 94088 USA

ISBN: (纸本)9781450336895

Modern accelerator programming frameworks, such as OpenCL (TM), organise threads into work-groups. Remote-scope promotion (RSP) is a language extension recently proposed by AMD researchers that is designed to enable applications, for the first time, both to optimise for the common case of intra-work-group communication (using memory scopes to provide consistency only within a work-group) and to allow occasional inter-work-group communication (as required, for instance, to support the popular load-balancing idiom of work stealing). We present the first formal, axiomatic memory model of OpenCL extended with RSP. We have extended the HERD memory model simulator with support for OpenCL kernels that exploit RSP, and used it to discover bugs in several litmus tests and a work-stealing queue, that have been used previously in the study of RSP. We have also formalised the proposed GPU implementation of RSP. The formalisation process allowed us to identify bugs in the description of RSP that could result in well-synchronised programs experiencing memory inconsistencies. We present and prove sound a new implementation of RSP that incorporates bug fixes and requires less non-standard hardware than the original implementation. This work, a collaboration between academia and industry, clearly demonstrates how, when designing hardware support for a new concurrent language feature, the early application of formal tools and techniques can help to prevent errors, such as those we have found, from making it into silicon.

关键词： Formal methods graphics processing unit (GPU) Isabelle OpenCL programming language implementation weak memory models work stealing

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ShamDroid: Gracefully Degrading Functionality in the Presence of Limited Resource Access 2015

ShamDroid: Gracefully Degrading Functionality in the Presenc...

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ACM SIGPLAN International conference on object-oriented programming, systems, languages, and applications (oopsla)

作者： Brutschy, Lucas Ferrara, Pietro Tripp, Omer Pistoia, Marco Swiss Fed Inst Technol Dept Comp Sci Zurich Switzerland IBM Thomas J Watson Res Ctr Yorktown Hts NY USA

ISBN: (纸本)9781450336895

Given a program whose functionality depends on access to certain external resources, we investigate the question of how to gracefully degrade functionality when a subset of those resources is unavailable. The concrete setting motivating this problem statement is mobile applications, which rely on contextual data (e.g., device identifiers, user location and contacts, etc.) to fulfill their functionality. In particular, we focus on the Android platform, which mediates access to resources via an installation-time permission model. On the one hand, granting an app the permission to access a resource (e.g., the device ID) entails privacy threats (e.g., releasing the device ID to advertising servers). On the other hand, denying access to a resource could render the app useless (e.g., if inability to read the device ID is treated as an error state). Our goal is to specialize an existing Android app in such a way that it is disabled from accessing certain sensitive resources (or contextual data) as specified by the user, while still being able to execute functionality that does not depend on those resources. We present SHAMDROID, a program transformation algorithm, based on specialized forms of program slicing, backwards static analysis and constraint solving, that enables the use of Android apps with partial permissions. We rigorously state the guarantees provided by SHAMDROID w.r.t. functionality maximization. We provide an evaluation over the top 500 Google Play apps and report on an extensive comparative evaluation of SHAMDROID against three other state-of-theart solutions (APM, XPrivacy, and Google App Ops) that mediate resource access at the system (rather than app) level. SHAMDROID performs better than all of these tools by a significant margin, leading to abnormal behavior in only 1 out of 27 apps we manually investigated, compared to the other solutions, which cause crashes and abnormalities in 9 or more of the apps. This demonstrates the importance of performing a

关键词： Security Verification Static Program Analysis Android applications Privacy

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Special issue on programming based on actors, agents and decentralized control

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SCIENCE OF COMPUTER programming 2015年 98卷 117-119页

作者： Ricci, Alessandro Agha, Gul Bordini, Rafael H. Marron, Assaf Univ Bologna I-40126 Bologna Italy Univ Illinois Champaign IL USA FACIN PUCRS Porto Alegre RS Brazil Weizmann Inst Sci Dept Comp Sci & Appl Math IL-76100 Rehovot Israel

The AGEREI workshop(1) has been organized with the ACM SPLASH conference since 2011. The workshop has brought together researchers in programming systems, languages, and applications based on actors, active/concurrent objects, agents, and more broadly, high-level programming paradigms which facilitate decentralized control. The goal of the workshop is to promote use of such paradigms to address the problem of developing software for complex, real-world applications. The AGERE workshop is a follow on to workshops on object-based Concurrent programming which were organized twenty years earlier in conjunction with oopsla [1-3]. In the last two decades, concurrency and distribution have become part of everyday programming. In this context, the objective of AGEREI is to foster the development and adoption of high-level programming paradigms embracing concurrency at the core of the developed abstractions and constructs. This special issue collects extended and enhanced versions of selected papers from AGERE! 2011 and 2012 which underwent additional review cycles. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Actors Agent-oriented programming Concurrent and distributed programming Behavioral programming

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Checks and Balances Constraint Solving without Surprises in object-Constraint programming languages

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ACM SIGPLAN NOTICES 2015年第10期50卷 767-782页

作者： Felgentreff, Tim Millstein, Todd Borning, Alan Hirschfeld, Robert Viewpoints Res Inst CDG SAP Labs Potsdam Germany Hasso Plattner Inst Potsdam Germany Univ Calif Los Angeles Los Angeles CA USA Univ Washington Seattle WA 98195 USA

object-constraint programming systems integrate declarative constraint solving with imperative, object-oriented languages, seamlessly providing the power of both paradigms. However, experience with object-constraint systems has shown that giving too much power to the constraint solver opens up the potential for solutions that are surprising and unintended as well as for complex interactions between constraints and imperative code. On the other hand, systems that overly limit the power of the solver, for example by disallowing constraints involving mutable objects, object identity, or polymorphic message sends, run the risk of excluding the core object-oriented features of the language from the constraint part, and consequently not being able to express declaratively a large set of interesting problem solutions. In this paper we present design principles that tame the power of the constraint solver in object-constraint languages to avoid difficult corner cases and surprising solutions while retaining the key features of the approach, including constraints over mutable objects, constraints involving object identity, and constraints on the results of message sends. We present our solution concretely in the context of the Babelsberg object-constraint language framework, providing both an informal description of the resulting language and a formal semantics for a core subset of it. We validate the utility of this semantics with an executable version that allows us to run test programs and to verify that they provide the same results as existing implementations of Babelsberg in JavaScript, Ruby, and Smalltalk.

关键词： Constraints object-Constraint programming Constraint Imperative programming Executable Semantics Test Suites

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The Chemical Approach to Typestate-oriented programming

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ACM SIGPLAN NOTICES 2015年第10期50卷 917-934页

作者： Crafa, Silvia Padovani, Luca Univ Padua I-35100 Padua Italy Univ Turin I-10124 Turin Italy

We study a novel approach to typestate-oriented programming based on the chemical metaphor: state and operations on objects are molecules of messages and state transformations are chemical reactions. This approach allows us to investigate typestate in an inherently concurrent setting, whereby objects can be accessed and modified concurrently by several processes, each potentially changing only part of their state. We introduce a simple behavioral type theory to express in a uniform way both the private and the public interfaces of objects, to describe and enforce structured object protocols consisting of possibilities, prohibitions, and obligations, and to control object sharing.

关键词： Typestate concurrency behavioral types join calculus

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Scrap Your Boilerplate with object Algebras

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ACM SIGPLAN NOTICES 2015年第10期50卷 127-146页

作者： Zhang, Haoyuan Chu, Zewei Oliveira, Bruno C. D. S. van der Storm, Tijs Univ Hong Kong Hong Kong Hong Kong Peoples R China CWI Amsterdam Netherlands

Traversing complex Abstract Syntax Trees (ASTs) typically requires large amounts of tedious boilerplate code. For many operations most of the code simply walks the structure, and only a small portion of the code implements the functionality that motivated the traversal in the first place. This paper presents a type-safe Java framework called Shy that removes much of this boilerplate code. In Shy object Algebras are used to describe complex and extensible AST structures. Using Java annotations Shy generates generic boilerplate code for various types of traversals. For a concrete traversal, users of Shy can then inherit from the generated code and override only the interesting cases. Consequently, the amount of code that users need to write is significantly smaller. Moreover, traversals using the Shy framework are also much more structure shy, becoming more adaptive to future changes or extensions to the AST structure. To prove the effectiveness of the approach, we applied Shy in the implementation of a domain-specific questionnaire language. Our results show that for a large number of traversals there was a significant reduction in the amount of user-defined code.

关键词： languages object algebras boilerplate code Java adaptive object-oriented programming

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Static Analysis of Event-Driven *** JavaScript applications

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ACM SIGPLAN NOTICES 2015年第10期50卷 505-519页

作者： Madsen, Magnus Tip, Frank Lhotak, Ondrej Univ Waterloo Waterloo ON N2L 3G1 Canada Samsung Res Amer Mountain View CA USA

Many JavaScript programs are written in an event-driven style. In particular, in server-side Node. js applications, operations involving sockets, streams, and files are typically performed in an asynchronous manner, where the execution of listeners is triggered by events. Several types of programming errors are specific to such event-based programs (e.g., unhandled events, and listeners that are registered too late). We present the event-based call graph, a program representation that can be used to detect bugs related to event handling. We have designed and implemented three analyses for constructing event-based call graphs. Our results show that these analyses are capable of detecting problems reported on StackOverflow. Moreover, we show that the number of false positives reported by the analysis on a suite of small Node. js applications is manageable.

关键词： event based-systems static analysis JavaScript

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How Scale Affects Structure in Java Programs

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ACM SIGPLAN NOTICES 2015年第10期50卷 675-694页

作者： Lopes, Cristina V. Ossher, Joel Univ Calif Irvine Bren Sch Informat & Comp Sci Irvine CA 92697 USA

Many internal software metrics and external quality attributes of Java programs correlate strongly with program size. This knowledge has been used pervasively in quantitative studies of software through practices such as normalization on size metrics. This paper reports size-related super- and sublinear effects that have not been known before. Findings obtained on a very large collection of Java programs - 30,911 projects hosted at Google Code as of Summer 2011 - unveils how certain characteristics of programs vary disproportionately with program size, sometimes even non-monotonically. Many of the specific parameters of nonlinear relations are reported. This result gives further in-sights for the differences of "programming in the small" vs. "programming in the large." The reported findings carry important consequences for OO software metrics, and software research in general: metrics that have been known to correlate with size can now be properly normalized so that all the information that is left in them is size-independent.

关键词： object oriented Programs Metrics Linear Regression Models

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