@Param support for enum

[Joe Kearney]

Hi,

Would you be interested in having @Param support enum fields? By
comparison, Caliper interprets @Param with no args to mean all enum values,
and (I think) loads specific named enum values @Param("FOO", "BAR").
Example below.

I've found this an easy way of describing the benchmark state space for
comparative tests of different implementations.

A workaround in jmh 0.7.3 is for the @Param("FOO", "BAR") field to be a
String, and set another field using Enum#valueOf() in a @Setup method. You
can make it use the whole set of enum values with OptionBuilder.param() and
some munging of the Enum#values() array, but there's no trivial way to do
it.

Most importantly, is there a reason that doing something like this would
contaminate the benchmark results? Is there a worry about the cost of the
extra method indirection? Perhaps that could be inlined if there's only one
enum value used per benchmark? I guess a lot of this could be benchmarked
as well.

Thanks,
Joe

@State(Scope.Benchmark)
public class BenchmarkWithEnums {
  enum Implementation {
    FOO {
      @Override void doYourThang() {
        System.out.println("Foo");
      }
    },
    BAR {
      @Override void doYourThang() {
        System.out.println("Bar");
      }
    };

    abstract void doYourThang();
  }

  @Param
  private Implementation impl;

  @GenerateMicroBenchmark
  public void runTheBenchmark() {
    impl.doYourThang();
  }
}