Actors may synchronize, safely! *

International audienceWe study deadlock detection in an actor model with wait-by-necessity synchronizations, a lightweight technique that synchronizes invocations when the corresponding values are strictly needed. This approach relies on the use of futures that are not given an explicit " Future " type. The approach we adopt allow the implicit synchronization on the availability of some value (where the producer of the value might be decided at runtime), whereas previous work allowed only explicit synchronization on the termination of a well-identified request. This way we are able to analyse the data-flow synchronization inherent to languages that feature wait-by-necessity. We provide a type-system and a solver inferring the type of a program so that deadlocks can be identified statically. As a consequence we can automatically verify the absence of deadlocks in actor programs with wait-by-necessity synchronizations

Analysis of Synchronisations in Stateful Active Objects

International audienceThis paper presents a static analysis technique based on effects and behavioural types for deriving synchronisation patterns of stateful active objects and verifying the absence of deadlocks in this context. This is challenging because active objects use futures to refer to results of pending asynchronous invocations and because these futures can be stored in object fields, passed as method parameters, or returned by invocations. Our effect system traces the access to object fields, thus allowing us to compute behavioural types that express synchronisation patterns in a precise way. The behavioural types are thereafter analysed by a solver that discovers potential deadlocks

Analysis of synchronisation patterns in stateful active objects

This paper presents a static analysis technique based on effect and behavioural types for deriving synchronisation patterns of stateful active objects and verifying their safety -- e.g.~absence of deadlocks. This is challenging because active objects use futures to refer to results of pending asynchronous invocations and because these futures can be stored in object fields, passed as method parameters, or returned by invocations.Our effect system traces the access to object fields, thus allowing us to compute behavioural types that express synchronisation patterns in a precise way.The behavioural types are thereafter analysed by a solver that discovers potential deadlocks

Actors may synchronize, safely! *

International audienceWe study deadlock detection in an actor model with wait-by-necessity synchronizations, a lightweight technique that synchronizes invocations when the corresponding values are strictly needed. This approach relies on the use of futures that are not given an explicit " Future " type. The approach we adopt allow the implicit synchronization on the availability of some value (where the producer of the value might be decided at runtime), whereas previous work allowed only explicit synchronization on the termination of a well-identified request. This way we are able to analyse the data-flow synchronization inherent to languages that feature wait-by-necessity. We provide a type-system and a solver inferring the type of a program so that deadlocks can be identified statically. As a consequence we can automatically verify the absence of deadlocks in actor programs with wait-by-necessity synchronizations

Deadlock analysis of asynchronous sequential processes

In this thesis we present ad study an object-oriented language, characterized by two different types of objects, passive and active objects, of which we define the operational syntax and semantics. For this language we also define the type system, that will be used for the type checking and for the extraction of behavioral types, which are an abstract description of the behavior of the methods, used in deadlock analysis. Programs can manifest deadlock due to the errors of the programmer. To statically identify possible unintended behaviors we studied and implemented a technique for the analysis of deadlock based on behavioral types

Analysis of synchronisation patterns in stateful active objects

This paper presents a static analysis technique based on effect and behavioural types for deriving synchronisation patterns of stateful active objects and verifying their safety -- e.g.~absence of deadlocks. This is challenging because active objects use futures to refer to results of pending asynchronous invocations and because these futures can be stored in object fields, passed as method parameters, or returned by invocations.Our effect system traces the access to object fields, thus allowing us to compute behavioural types that express synchronisation patterns in a precise way.The behavioural types are thereafter analysed by a solver that discovers potential deadlocks

Effectiveness of Calcium Phosphate Desensitising Agents in Dental Hypersensitivity Over 24 Weeks of Clinical Evaluation

Background: Calcium phosphate-based compounds are used to treat dental hypersensitivity (DH). Their long-term clinical behaviour needs further research. This study compared the 24-week effectiveness of Teethmate Desensitizer (TD), a pure tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) powder/water, to that of Dentin Desensitizer (DD), and Bite & White ExSense (BWE), both of calcium phosphate crystallites. Methods: A total of 105 subjects were selected. A random table was utilised to form three groups of 35 subjects. DH was evaluated using the evaporative sensitivity, tactile sensitivity tests, and the visual analogue scale (VAS) of pain. Response was recorded before the application of the materials (Pre-1), immediately after (Post-0), at 1 week (Post-1), 4 weeks (Post-2), 12 weeks (Post-3) and 24 weeks (Post-4). The non-parametric distribution was assessed with the Shapiro–Wilk statistical test. Intra-group differences for the six time points were evaluated with the Friedman statistical test and the Kruskal–Wallis test. Results: All the materials decreased DH after 24 weeks in comparison to Pre-1. However, the TTCP/DCPD cement showed the greatest statistical efficiency. Conclusions: The significant decrease of VAS scores produced by TD in the long term suggest the material as the most reliable in the clinical relief of DH