Memory Mode: Adding 3rd and last part support for synchronous instruments - exponential histogram

[asafm]

Epic

This is the 4th PR out of several that implement #5105. See the complete plan here.
Specifically, this is the 3rd and last part that completes the implementation of MemoryMode for the synchronous instrument: exponential histogram.

What was done here?

• Expanded the existing JMH-based benchmark test to cover any instrument, hence renamed it to InstrumentGarbageCollectionBenchmark and InstrumentGarbageCollectionBenchmarkTest.
  • It's now "plugin" based, and currently, two instruments are tested: asynchronous counter and exponential histogram.
  • Reduced the number of iterations and batch size to a number tested to discover at least a 5% diff in the allocation rate. This makes the test much faster
• I fixed the last GC issue at Base2ExponentialHistogramIndexer, which allocated lots of implicit classes by not using the local variable.

I will convert it from draft to PR once the previous PR is merged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (dbaba2f) 91.03% compared to head (82337b5) 91.04%.
Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #6136   +/-   ##
=========================================
  Coverage     91.03%   91.04%           
  Complexity     5648     5648           
=========================================
  Files           619      619           
  Lines         16443    16443           
  Branches       1663     1663           
=========================================
+ Hits          14969    14970    +1     
  Misses         1010     1010           
+ Partials        464      463    -1     

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[asafm]

@jack-berg Ready for review

[asafm]

The markdown links check fails, but I don't know how to fix it.

[jack-berg]

Just one small recommendation.

[jack-berg]

#nit: If you change instrumentTesterClass from Class<? extends InstrumentTester> to Supplier<InstrumentTester>, and configure each element in the TestInstrumentType enum with a factory method for creating new instances of InstrumentTester:

public enum TestInstrumentType {
  ASYNC_COUNTER(AsyncCounterTester::new),
  EXPONENTIAL_HISTOGRAM(ExponentialHistogramTester::new);

  final Supplier<InstrumentTester> instrumentTesterSupplier;

  TestInstrumentType(Supplier<InstrumentTester> instrumentTesterSupplier) {
    this.instrumentTesterSupplier = instrumentTesterSupplier;
  }
 
  ..

[asafm]

Thanks. Much better.
I did it with an abstract method since error prone recommended it, and it does seem cleaner.

I also added the ProfileBenchmark and linked to it from the test

[asafm]

@jack-berg All set