[QC-1346] Scaffolding to share common code among QC data processors#2660
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knopers8 wants to merge 4 commits intoAliceO2Group:masterfrom
Open
[QC-1346] Scaffolding to share common code among QC data processors#2660knopers8 wants to merge 4 commits intoAliceO2Group:masterfrom
knopers8 wants to merge 4 commits intoAliceO2Group:masterfrom
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Actor is a template base class for all QC Data Processors. It is supposed to bring their commonalities together, such as: service initialization, Data Processing Layer adoption, retrieving configuration and runtime parameters, interactions with controlling entities (DPL driver, AliECS, ODC). The design is based on CRTP (see the web for explanation), which allows us to: - avoid code repetition in implementing aforementioned commonalities - optionally perform certain actions depending on traits of an Actor specialization. CRTP, in contrast to dynamic inheritance, is also advertised to avoid performance impact due to vtable lookups. It is certainly a nice bonus in our case, but it was not the main motivation for CRTP-based approach. To allow for compile-time customization of centralized Actor features, we require each concrete Actor to implement an ActorTraits structure with certain parameters which is enforced with ValidActorTraits concept. The traits are separated from the main Actor class to improve readability and allow for shorter compilation times by allowing many helper functions avoid including Actor.h and a corresponding actor specialization. For additional savings on compilation time and clutter in code, we validate ActorTraits specializations with a concept only in Actor, but this could be revisited if proven wrong. This commit paves the path for refactoring existing QC data processors as Actor specializations/children.
Clang complains that:
```
SOURCES/QualityControl/2660/0/Framework/test/testActor.cxx
/Volumes/build/alice-ci-workdir/qualitycontrol-o2/sw/SOURCES/QualityControl/2660/0/Framework/test/testActor.cxx:97:5: error: call to consteval function 'o2::quality_control::core::UnrequestedAccessActor::assertNoAccessToServices<o2::quality_control::core::UnrequestedAccessActor>' is not a constant expression
97 | assertNoAccessToServices<UnrequestedAccessActor>();
| ^
/Volumes/build/alice-ci-workdir/qualitycontrol-o2/sw/SOURCES/QualityControl/2660/0/Framework/test/testActor.cxx:97:5: note: implicit use of 'this' pointer is only allowed within the evaluation of a call to a 'constexpr' member function
1 error generated.
```
GCC is fine and is able to process it as a consteval expression. Let's keep both happy by using constexpr, given it's just a test.
to make clang happy again
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Actor is a template base class for all QC Data Processors. It is supposed to bring their commonalities together, such as: service initialization, Data Processing Layer adoption, retrieving configuration and runtime parameters, interactions with controlling entities (DPL driver, AliECS, ODC).
The design is based on CRTP (see the web for explanation), which allows us to:
To allow for compile-time customization of centralized Actor features, we require each concrete Actor to implement an ActorTraits structure with certain parameters which is enforced with ValidActorTraits concept. The traits are separated from the main Actor class to improve readability and allow for shorter compilation times by allowing many helper functions avoid including Actor.h and a corresponding actor specialization. For additional savings on compilation time and clutter in code, we validate ActorTraits specializations with a concept only in Actor, but this could be revisited if proven wrong.
This commit paves the path for refactoring existing QC data processors as Actor specializations/children.