@MetricOptions process based on condition

[hrothwell]

Opened in relation to #896

Opening as draft initially for asking a few questions. No longer draft as of Dec 3rd 2024

Plan + thoughts:

• Add new value onto MetricOptions annotation that takes in classes used to filter
  • Question 1: I looked into using Condition as I was thinking this might work similarly to the Requires annotation, but I was unsure if it was possible to retrieve this in these metric interceptors as things currently are. Is there a way to retrieve a ConditionContext while in these interceptors?
  • Question 2: Right now these are classes that are intended to be initialized (which I also could not find how Condition impls were being initialized / used), but if needing access to the environment (Beans, active environments, etc) these may need to follow the pattern that AbstractMethodTagger does right now where it is a bean, injected into the metric interceptors, filtered, etc. Is there a way to fetch any context related information without defining a Bean or anything of the sort?
• Use new classes to determine if metric will be calculated/processed/etc in TimedInterceptor and CountedInterceptor
  • Only did TimedInterceptor prior to opening due to potential for things to change based on feedback.

Edit December 3rd 2024:

• using expressions to evaluate condition, thank you for the reminder/recommendation @graemerocher
• Create MetricOptionsUtil to share means of fetching the condition between CountedInterceptor and TimedInterceptor
  • Thought that maybe the methods of fetching the other properties from the annotation could also be shared here, but wanted to limit changes in this PR. If approved / merged I am planning to do a follow-up PR to do that additional change
• Tests showing that evaluated condition prevents metric from being published / calculated when false

[graemerocher]

have you considered using expressions for this? See https://micronaut-projects.github.io/micronaut-cache/latest/guide/#conditional and https://github.com/micronaut-projects/micronaut-cache/blob/6a3e54f85b6a468c4f50265ff6a35fde218e0c71/cache-core/src/main/java/io/micronaut/cache/interceptor/CacheInterceptor.java#L537

[hrothwell]

have you considered using expressions for this? See https://micronaut-projects.github.io/micronaut-cache/latest/guide/#conditional and https://github.com/micronaut-projects/micronaut-cache/blob/6a3e54f85b6a468c4f50265ff6a35fde218e0c71/cache-core/src/main/java/io/micronaut/cache/interceptor/CacheInterceptor.java#L537

I had not, in fact I actually forgot that those existed / not thought about it. I will take a look at using that to build this out 👍

[hrothwell]

@graemerocher thank you for that suggestion!

[graemerocher]

Thanks could you add some documentation somewhere?

[graemerocher]

can be final and probably doesn't need to be public

[hrothwell]

when not public it is not callable from the interceptors due to differing packages

[graemerocher]

add javadoc and make not public

[hrothwell]

Similar situation as the whole class being not public: if public is removed it is unable to be called where it currently is

[graemerocher]

could you document @MetricOptions and the conditional support here https://github.com/micronaut-projects/micronaut-micrometer/edit/5.9.x/src/main/docs/guide/metricsAnnotations.adoc ?

[graemerocher]

Thanks for the contribution!