Expose TemporalitySelector funcs

internal/shared/otlp/otlpmetric/oconf/envconfig.go.tmpl

@@ -18,7 +18,6 @@ import (
 	"{{ .envconfigImportPath }}"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
 // DefaultEnvOptionsReader is the default environments reader.
@@ -163,43 +162,18 @@ func withTLSConfig(c *tls.Config, fn func(*tls.Config)) func(e *envconfig.EnvOpt
 func withEnvTemporalityPreference(n string, fn func(metric.TemporalitySelector)) func(e *envconfig.EnvOptionsReader) {
 	return func(e *envconfig.EnvOptionsReader) {
 		if s, ok := e.GetEnvValue(n); ok {
-			switch strings.ToLower(s) {
-			case "cumulative":
-				fn(cumulativeTemporality)
-			case "delta":
-				fn(deltaTemporality)
-			case "lowmemory":
-				fn(lowMemory)
-			default:
-				global.Warn(
-					"OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE is set to an invalid value, ignoring.",
-					"value",
-					s,
-				)
-			}
-		}
-	}
-}
-
-func cumulativeTemporality(metric.InstrumentKind) metricdata.Temporality {
-	return metricdata.CumulativeTemporality
-}
 
-func deltaTemporality(ik metric.InstrumentKind) metricdata.Temporality {
-	switch ik {
-	case metric.InstrumentKindCounter, metric.InstrumentKindHistogram, metric.InstrumentKindObservableCounter:
-		return metricdata.DeltaTemporality
-	default:
-		return metricdata.CumulativeTemporality
-	}
-}
+      if pref := metric.TemporalityPreference(s); pref.IsValid() {
+        fn(metric.TemporalitySelectorForPreference(pref))
+        return
+      }
 
-func lowMemory(ik metric.InstrumentKind) metricdata.Temporality {
-	switch ik {
-	case metric.InstrumentKindCounter, metric.InstrumentKindHistogram:
-		return metricdata.DeltaTemporality
-	default:
-		return metricdata.CumulativeTemporality
+			global.Warn(
+				"OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE is set to an invalid value, ignoring.",
+				"value",
+				s,
+			)
+		}
 	}
 }
 

internal/shared/otlp/otlpmetric/oconf/options.go.tmpl

@@ -361,6 +361,13 @@ func WithTemporalitySelector(selector metric.TemporalitySelector) GenericOption
 	})
 }
 
+func WithTemporalityPreference(pref metric.TemporalityPreference) GenericOption {
+	return newGenericOption(func(cfg Config) Config {
+		cfg.Metrics.TemporalitySelector = metric.TemporalitySelectorForPreference(pref)
+		return cfg
+	})
+}
+
 func WithAggregationSelector(selector metric.AggregationSelector) GenericOption {
 	return newGenericOption(func(cfg Config) Config {
 		cfg.Metrics.AggregationSelector = selector

sdk/metric/reader.go

@@ -127,10 +127,40 @@ type TemporalitySelector func(InstrumentKind) metricdata.Temporality
 // DefaultTemporalitySelector is the default TemporalitySelector used if
 // WithTemporalitySelector is not provided. CumulativeTemporality will be used
 // for all instrument kinds if this TemporalitySelector is used.
-func DefaultTemporalitySelector(InstrumentKind) metricdata.Temporality {
+func DefaultTemporalitySelector(k InstrumentKind) metricdata.Temporality {
+	return CumulativeTemporalitySelector(k)
+}
+
+// CumulativeTemporalitySelector is the TemporalitySelector that uses
+// a cumulative temporality for all instrument kinds.
+func CumulativeTemporalitySelector(InstrumentKind) metricdata.Temporality {
 	return metricdata.CumulativeTemporality
 }
 
+// DeltaTemporalitySelector is the TemporalitySelector that uses
+// a delta temporality for instrument kinds: counter, histogram, observable counter
+// All other instruments use cumulative temporality.
+func DeltaTemporalitySelector(k InstrumentKind) metricdata.Temporality {
+	switch k {
+	case InstrumentKindCounter, InstrumentKindHistogram, InstrumentKindObservableCounter:
+		return metricdata.DeltaTemporality
+	default:
+		return metricdata.CumulativeTemporality
+	}
+}
+
+// LowMemoryTemporalitySelector is the TemporalitySelector that uses
+// delta temporality for counters and histograms. All other instruments use
+// cumulative temporality.
+func LowMemoryTemporalitySelector(k InstrumentKind) metricdata.Temporality {
+	switch k {
+	case InstrumentKindCounter, InstrumentKindHistogram:
+		return metricdata.DeltaTemporality
+	default:
+		return metricdata.CumulativeTemporality
+	}
+}
+
 // AggregationSelector selects the aggregation and the parameters to use for
 // that aggregation based on the InstrumentKind.
 //

sdk/metric/temporality.go

@@ -0,0 +1,54 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package metric // import "go.opentelemetry.io/otel/sdk/metric"
+
+import "strings"
+
+// TemporalityPreference defines the user's desired temporality for metrics instruments.
+type TemporalityPreference string
+
+const (
+	// TemporalityPreferenceDefault indicates the SDK's default temporality should be used.
+	TemporalityPreferenceDefault TemporalityPreference = ""
+
+	// TemporalityPreferenceCumulative indicates a cumulative temporality should be used.
+	TemporalityPreferenceCumulative TemporalityPreference = "cumulative"
+
+	// TemporalityPreferenceDelta indicates a delta temporality should be used.
+	TemporalityPreferenceDelta TemporalityPreference = "delta"
+
+	// TemporalityPreferenceLowMemory indicates temporality preference that optimizes memory use.
+	TemporalityPreferenceLowMemory TemporalityPreference = "lowmemory"
+)
+
+// IsValid returns true whether the preference is a valid string constant.
+func (t TemporalityPreference) IsValid() bool {
+	switch t.lowercase() {
+	case TemporalityPreferenceCumulative,
+		TemporalityPreferenceDelta,
+		TemporalityPreferenceLowMemory,
+		TemporalityPreferenceDefault:
+		return true
+	default:
+		return false
+	}
+}
+
+func (t TemporalityPreference) lowercase() TemporalityPreference {
+	return TemporalityPreference(strings.ToLower(string(t)))
+}
+
+// TemporalitySelectorForPreference will return a TemporalitySelector for the given preference.
+func TemporalitySelectorForPreference(t TemporalityPreference) TemporalitySelector {
+	switch t.lowercase() {
+	case TemporalityPreferenceCumulative:
+		return CumulativeTemporalitySelector
+	case TemporalityPreferenceDelta:
+		return DeltaTemporalitySelector
+	case TemporalityPreferenceLowMemory:
+		return LowMemoryTemporalitySelector
+	default:
+		return DefaultTemporalitySelector
+	}
+}