Nearly ten years after its first presentation and five years after its first application to operating systems, the suitability of AspectOriented Programming (AOP) for the development of operating system kernels is still highly in dispute. While the AOP advocacy emphasizes the benefits of AOP towards better configurability and maintainability of system software, most kernel developers express a sound skepticism regarding the thereby induced runtime and memory costs: Operating system kernels have to be lean and efficient. We have analyzed the runtime and memory costs of aspects in general, on the level of µ-benchmarks, and by refactoring and extending the eCos operating system kernel using AspectC++, an AOP extension to the C++ language. Our results show that most AOP features do not induce a intrinsic overhead and that the actual overhead induced by AspectC++ is very low. We have also analyzed a test case with significant aspect-related costs. This example shows how the structure of the underlying kernel can have a negative impact on aspect implementations and how these costs can be avoided by an aspect-aware design. Based on this analysis, our conclusion is that AOP is suitable for the development of operating system kernels and other kinds of highly efficient infrastructure software.

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Abstract. Besides object-orientation, generic types or templates and aspectoriented programming (AOP) gain increasing popularity as they provide additional dimensions of decomposition. Most modern programming languages like Ada, Eiffel, and C++ already have built-in support for templates. For Java and C# similar extensions will be available in the near future. Even though promising, the combination of aspects with generic and generative programming is still a widely unexplored field. This paper presents our extensions to the AspectC++ language, an aspect-oriented C++ derivate. By these extensions aspects can now affect generic code and exploit the potentials of generic code and template metaprogramming in their implementations. This allows aspects to inject template metaprograms transparently into the component code. A case study demonstrates that this feature enables the development of highly expressive and efficient generic aspect implementations in AspectC++. A discussion whether these concepts are applicable in the context of other aspect-oriented language extensions like AspectJ rounds up our contribution.

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