MetricCollector revamp.

[geeknoid]

MetricCollector revamp.

• This now has a considerably simpler API surface allowing you to collect
  data for a single instrument at a time.

• You can now snapshot all recorded measurements and apply various
  filters over lists of measurements.

• General shape of the API looks similar in style to the FakeLogger.
  You can now take snapshots of existing state, as a client you never get
  your hands on "live" state, which helps with racy code.

• There is now a WaitForMeasurementsAsync function which is helpful to
  simplify testing async logic.

Microsoft Reviewers: Open in CodeFlow

[noahfalk]

I like it a lot better than the previous API. Added some suggestions inline.

[noahfalk]

cc @samsp-msft

[geeknoid]

@noahfalk @tarekgh Addressed Noah's feedback. It's looking even more like InstrumentRecorder, but with time support, wait support, and a few additional conveniences.

[tarekgh]

@geeknoid I looked at MetricCollector and it looks good to me. I don't have any more feedback.

@JamesNK do you have any feedback from aspnet side replacing InstrumentRecorder with MetricCollector?

[tarekgh]

do you need this empty file? Microsoft.Extensions.Telemetry.Console.json

[geeknoid]

@tarekgh Where do you see this .json file? That's an old file that should have been deleted last week when I retired the console package. I don't see that file in my PR.

[tarekgh]

Where do you see this .json file? That's an old file that should have been deleted last week when I retired the console package. I don't see that file in my PR.

[geeknoid]

@noahfalk Now at 100% code coverage, so ready to check in. Any more feedback?

[noahfalk]

@noahfalk Now at 100% code coverage, so ready to check in. Any more feedback?

You are speedy :) I will take a look later this evening at your updated version.

[JamesNK]

I had a lot of feedback for the wait for measurement methods. I created a PR with the changes that merges into this branch: #4091

[noahfalk]

A few last suggestions, but this is looking pretty good to me. I think it is capturing all the things I liked about the original InstrumentRecorder and has removed portions of the MetricCollector API that felt confusing. Hopefully it still felt pretty ergonomic to use?