* Merge instrument cache to inserter
The current pipeline resolution path will only add the resolved
aggregators to the pipeline when it creates one (cache miss). It will
not add it if there is a cache hit. This means (since we cache
instruments at the meter level, not the pipeline level) the first reader
in a multiple-reader setup is the only one that will collect data for
that aggregator. All other readers will have a cache hit and nothing is
added to the pipeline. This is causing #3720.
This resolves#3720 by moving the instrument caching into the inserter.
This means aggregators are cached at the reader level, not the meter.
* Rename aggCV to aggVal
---------
Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>
An instrument is defined by a name, description, unit, and kind. The
instrumentID contains more identifying information than these fields.
The additional information it contains relate to what the OTel metric
data-model calls a stream. Match the terminology and remove using the
instrumentID name in case we want to use it for something else (say,
when caching instruments).
* Add the cache type
* Add cache unit tests
* Test cache concurrency
* Add the instrumentCache
* Use the instrumentCache to deduplicate creation
* Drop unique check from addAggregator
* Fix aggregatorCache* docs
* Update cachedAggregator and aggregator method docs
* Remove unnecessary type constraint
* Remove unused errAlreadyRegistered
* Rename to not shadow imports
* Add changes to changelog
* Fix changelog English
* Store resolvers in the meter instead of caches
* Test all Aggregator[N] impls are comparable
* Fix lint
* Add documentation that Aggregators need to be comparable
* Update sdk/metric/internal/aggregator.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/instrument.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/instrument.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update sdk/metric/internal/aggregator_test.go
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Fix pipeline_test.go use of newInstrumentCache
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
