1 files changed, 32 insertions, 36 deletions

diff --git a/vendor/go.opentelemetry.io/otel/sdk/metric/exemplar.go b/vendor/go.opentelemetry.io/otel/sdk/metric/exemplar.go
index 82619da78..0335b8ae4 100644
--- a/vendor/go.opentelemetry.io/otel/sdk/metric/exemplar.go
+++ b/vendor/go.opentelemetry.io/otel/sdk/metric/exemplar.go
@@ -4,51 +4,49 @@
 package metric // import "go.opentelemetry.io/otel/sdk/metric"
 
 import (
-	"os"
 	"runtime"
-	"slices"
 
-	"go.opentelemetry.io/otel/sdk/metric/internal/exemplar"
-	"go.opentelemetry.io/otel/sdk/metric/internal/x"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/metric/exemplar"
+	"go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
 )
 
-// reservoirFunc returns the appropriately configured exemplar reservoir
-// creation func based on the passed InstrumentKind and user defined
-// environment variables.
-//
-// Note: This will only return non-nil values when the experimental exemplar
-// feature is enabled and the OTEL_METRICS_EXEMPLAR_FILTER environment variable
-// is not set to always_off.
-func reservoirFunc[N int64 | float64](agg Aggregation) func() exemplar.FilteredReservoir[N] {
-	if !x.Exemplars.Enabled() {
-		return nil
-	}
-	// https://github.com/open-telemetry/opentelemetry-specification/blob/d4b241f451674e8f611bb589477680341006ad2b/specification/configuration/sdk-environment-variables.md#exemplar
-	const filterEnvKey = "OTEL_METRICS_EXEMPLAR_FILTER"
+// ExemplarReservoirProviderSelector selects the
+// [exemplar.ReservoirProvider] to use
+// based on the [Aggregation] of the metric.
+type ExemplarReservoirProviderSelector func(Aggregation) exemplar.ReservoirProvider
 
-	var filter exemplar.Filter
-
-	switch os.Getenv(filterEnvKey) {
-	case "always_on":
-		filter = exemplar.AlwaysOnFilter
-	case "always_off":
-		return exemplar.Drop
-	case "trace_based":
-		fallthrough
-	default:
-		filter = exemplar.SampledFilter
+// reservoirFunc returns the appropriately configured exemplar reservoir
+// creation func based on the passed InstrumentKind and filter configuration.
+func reservoirFunc[N int64 | float64](provider exemplar.ReservoirProvider, filter exemplar.Filter) func(attribute.Set) aggregate.FilteredExemplarReservoir[N] {
+	return func(attrs attribute.Set) aggregate.FilteredExemplarReservoir[N] {
+		return aggregate.NewFilteredExemplarReservoir[N](filter, provider(attrs))
 	}
+}
 
+// DefaultExemplarReservoirProviderSelector returns the default
+// [exemplar.ReservoirProvider] for the
+// provided [Aggregation].
+//
+// For explicit bucket histograms with more than 1 bucket, it uses the
+// [exemplar.HistogramReservoirProvider].
+// For exponential histograms, it uses the
+// [exemplar.FixedSizeReservoirProvider]
+// with a size of min(20, max_buckets).
+// For all other aggregations, it uses the
+// [exemplar.FixedSizeReservoirProvider]
+// with a size equal to the number of CPUs.
+//
+// Exemplar default reservoirs MAY change in a minor version bump. No
+// guarantees are made on the shape or statistical properties of returned
+// exemplars.
+func DefaultExemplarReservoirProviderSelector(agg Aggregation) exemplar.ReservoirProvider {
 	// https://github.com/open-telemetry/opentelemetry-specification/blob/d4b241f451674e8f611bb589477680341006ad2b/specification/metrics/sdk.md#exemplar-defaults
 	// Explicit bucket histogram aggregation with more than 1 bucket will
 	// use AlignedHistogramBucketExemplarReservoir.
 	a, ok := agg.(AggregationExplicitBucketHistogram)
 	if ok && len(a.Boundaries) > 0 {
-		cp := slices.Clone(a.Boundaries)
-		return func() exemplar.FilteredReservoir[N] {
-			bounds := cp
-			return exemplar.NewFilteredReservoir[N](filter, exemplar.Histogram(bounds))
-		}
+		return exemplar.HistogramReservoirProvider(a.Boundaries)
 	}
 
 	var n int
@@ -75,7 +73,5 @@ func reservoirFunc[N int64 | float64](agg Aggregation) func() exemplar.FilteredR
 		}
 	}
 
-	return func() exemplar.FilteredReservoir[N] {
-		return exemplar.NewFilteredReservoir[N](filter, exemplar.FixedSize(n))
-	}
+	return exemplar.FixedSizeReservoirProvider(n)
 }