InMemoryMetricsFactory.createGauge considers amount as delta

[mdouaihy]

Hello,

I am using the Java Jaeger client in my project. I stumbled upon InMemoryMetricsFactory and noticed a bug in the createGauge method.

In fact createGauge considers the amount as a delta whereas it's an absolute amount.

Current Behavior

return new Gauge() {
      @Override
      public void update(long amount) {
        value.addAndGet(amount);
      }
    };

Suggested Behavior

return new Gauge() {
      @Override
      public void update(long amount) {
        value.getAndSet(amount);
      }
    };

[jpkrohling]

Would you like to contribute a fix? If you need help in submitting your first contribution, let me know.

[mdouaihy]

I will be with pleasure to provide a first fix PR soon.

[mdouaihy]

Pull request #463 was added for that purpose.