Resolve https://github.com/open-telemetry/opentelemetry-go/issues/5249
### Spec
> exemplar_reservoir: A functional type that generates an exemplar
reservoir a MeterProvider will use when storing exemplars. This
functional type needs to be a factory or callback similar to aggregation
selection functionality which allows different reservoirs to be chosen
by the aggregation.
> Users can provide an exemplar_reservoir, but it is up to their
discretion. Therefore, the stream configuration parameter needs to be
structured to accept an exemplar_reservoir, but MUST NOT obligate a user
to provide one. If the user does not provide an exemplar_reservoir
value, the MeterProvider MUST apply a [default exemplar
reservoir](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#exemplar-defaults).
Also,
> the reservoir MUST be given the Attributes associated with its
timeseries point either at construction so that additional sampling
performed by the reservoir has access to all attributes from a
measurement in the "offer" method.
### Changes
In sdk/metric/exemplar, add:
* `exemplar.ReservoirProvider`
* `exemplar.HistogramReservoirProvider`
* `exemplar.FixedSizeReservoirProvider`
In sdk/metric, add:
* `metric.ExemplarReservoirProviderSelector` (func Aggregation ->
ReservoirProvider)
* `metric.DefaultExemplarReservoirProviderSelector` (our default
implementation)
* `ExemplarReservoirProviderSelector` added to `metric.Stream`
Note: the only required public types are
`metric.ExemplarReservoirProviderSelector` and
`ExemplarReservoirProviderSelector` in `metric.Stream`. Others are for
convenience and readability.
### Alternatives considered
#### Add ExemplarReservoirProvider directly to metric.Stream, instead of
ExemplarReservoirProviderSelector
This would mean users can configure a `func() exemplar.Reservoir`
instead of a `func(Aggregation) func() exemplar.Reservoir`.
I don't think this complies with the statement: `This functional type
needs to be a factory or callback similar to aggregation selection
functionality which allows different reservoirs to be chosen by the
aggregation.`. I'm interpreting "allows different reservoirs to be
chosen by the aggregation" as meaning "allows different reservoirs to be
chosen **based on the** aggregation", rather than meaning that the
aggregation is somehow choosing the reservoir.
### Future work
There is some refactoring I plan to do after this to simplify the
interaction between the internal/aggregate and exemplar package. I've
omitted that from this PR to keep the diff smaller.
---------
Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
Co-authored-by: Robert Pająk <pellared@hotmail.com>
From
https://github.com/open-telemetry/opentelemetry-go-contrib/pull/5654#discussion_r1617971674
Constructing a view requires an `Instrument` to be constructed. Given
`NewView` will not return an error directly when an empty instrument is
passed, it may be ideal for users to check this prior to making the
call. Instead of having all use-cases copy this code, export it so they
can just call the method.
* Add allow/deny attr filters
* Revert "Replace `Stream.AttributeFilter` with `AllowAttributeKeys` (#4288)"
This reverts commit 1633c74aea.
* Rename new attr filter funcs
Do not include the term "Attribute" in a creation function of the
"attribute" pkg.
* Update the AttributeFilter field documentation
* Add tests for filter creation funcs
* Add change to changelog
* Apply feedback
* Use NewDenyKeysFilter for allow-all and deny-list filters
* Remove links from field docs
These links do not render.
---------
Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>
* Deprecate the aggregation pkg
* Decouple the internal/aggregate from aggregation pkg
* Add Aggregation to the metric pkg
* Do not use sdk/metric/aggregation in stdoutmetric exporter
* Update all generated templates
* Update prom exporter
* Fix view example
* Add changes to changelog
* Update CHANGELOG.md
Co-authored-by: Robert Pająk <pellared@hotmail.com>
* Rename Sum to AggregationSum
* Fix comments
* Centralize validation of aggregation in pipeline
* Remove validation of agg in manual_reader selector opt
* Fix merge
---------
Co-authored-by: Robert Pająk <pellared@hotmail.com>
* Replace Stream AttributeFilter with AttributeKeys
* Rename Stream field AttributeKeys to AllowAttributeKeys
Ensure forward compatibility if a deny-list of attribute keys is ever
added.
* Add change to changelog
* Update PR number in changelog
* Update CHANGELOG.md
Co-authored-by: Damien Mathieu <42@dmathieu.com>
---------
Co-authored-by: Damien Mathieu <42@dmathieu.com>
* Add the InstrumentKind type and vars to sdk/metric
* Add the Instrument type to sdk/metric
* Add the Stream type to sdk/metric
* Add the View type to sdk/metric
* Add NewView to create Views matching OTel spec
* Add unit tests for NewView
* Add changes to changelog
* Apply suggestions from code review
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
* Update CHANGELOG.md
* Update match and mask comments of Instrument
* Explain wildcard logic in NewView with comment
* Drop views that replace name for multi-inst match
* Comment how users are expected to match zero-vals
* Remove InstrumentKind and Scope from Stream
* Fix redundant word in NewView comment
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>
