Add support for custom gauge adapters

[smarr]

At the moment, we have only a limited, predefined set of gauge adapters in ReBench.

With this PR, we add support to provide custom gauge adapters by specifying a path to a Python file, from which to load the adapter.

This way, we do not need to support all possible benchmark harnesses in ReBench, and can instead provide support when it's needed as a kind of plugin.

Previously, we could only use built-in parsers like this:

benchmark_suites:
  ExampleSuite:
    gauge_adapter: ReBenchLog

With this PR, a custom parser can be used like this:

benchmark_suites:
  ExampleSuite:
    gauge_adapter:
      MyClass: ./my_parser.py

Remaining Todos

• expand the documentation to sketch how to provide a minimal custom implementation

[coveralls]

Coverage: 81.257% (+0.5%) from 80.721% when pulling 7ca4e62 on custom-gauge-adapters into 3914b3e on master.

[smarr]

@OctaveLarose could you give this a spin locally to see whether you can use this to get your gauge adapter to work as desired?

You probably want absolute imports in the python file for the gauge adapter, which is something I ran into when creating the ones for testing.

[OctaveLarose]

@OctaveLarose could you give this a spin locally to see whether you can use this to get your gauge adapter to work as desired?

You probably want absolute imports in the python file for the gauge adapter, which is something I ran into when creating the ones for testing.

Indeed, I had to switch to absolute imports. I can confirm it's functional! I would just suggest adding an explicit error message when the class can't be found (when _get_adapter_case_insensitively_from_module returns None) since I had originally forgotten to replace some MyClass entries with the name of my custom gauge adapter, and was confused why it was failing.

Also, if this gets merged, please make sure to update the rebench version on yuria so I can use it for my experiments

[smarr]

The latest commit will make sure it fails in the same way as for a misnamed standard gauge adapter.

[smarr]

And the last push adds a revised bit of documentation, with a minimal example on how to implement a custom adapter.

[smarr]

Some minor cleanups. If CI passes, I'll merge this and update branches.