feat(telemetry): instrument inference duration and frame age

vendor/go.opentelemetry.io/otel/sdk/metric/selector/simple/simple.go

@@ -0,0 +1,120 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package simple // import "go.opentelemetry.io/otel/sdk/metric/selector/simple"
+
+import (
+	"go.opentelemetry.io/otel/metric/sdkapi"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/exact"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/minmaxsumcount"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
+)
+
+type (
+	selectorInexpensive struct{}
+	selectorExact       struct{}
+	selectorHistogram   struct {
+		options []histogram.Option
+	}
+)
+
+var (
+	_ export.AggregatorSelector = selectorInexpensive{}
+	_ export.AggregatorSelector = selectorExact{}
+	_ export.AggregatorSelector = selectorHistogram{}
+)
+
+// NewWithInexpensiveDistribution returns a simple aggregator selector
+// that uses minmaxsumcount aggregators for `Histogram`
+// instruments.  This selector is faster and uses less memory than the
+// others in this package because minmaxsumcount aggregators maintain
+// the least information about the distribution among these choices.
+func NewWithInexpensiveDistribution() export.AggregatorSelector {
+	return selectorInexpensive{}
+}
+
+// NewWithExactDistribution returns a simple aggregator selector that
+// uses exact aggregators for `Histogram` instruments.  This
+// selector uses more memory than the others in this package because
+// exact aggregators maintain the most information about the
+// distribution among these choices.
+func NewWithExactDistribution() export.AggregatorSelector {
+	return selectorExact{}
+}
+
+// NewWithHistogramDistribution returns a simple aggregator selector
+// that uses histogram aggregators for `Histogram` instruments.
+// This selector is a good default choice for most metric exporters.
+func NewWithHistogramDistribution(options ...histogram.Option) export.AggregatorSelector {
+	return selectorHistogram{options: options}
+}
+
+func sumAggs(aggPtrs []*export.Aggregator) {
+	aggs := sum.New(len(aggPtrs))
+	for i := range aggPtrs {
+		*aggPtrs[i] = &aggs[i]
+	}
+}
+
+func lastValueAggs(aggPtrs []*export.Aggregator) {
+	aggs := lastvalue.New(len(aggPtrs))
+	for i := range aggPtrs {
+		*aggPtrs[i] = &aggs[i]
+	}
+}
+
+func (selectorInexpensive) AggregatorFor(descriptor *sdkapi.Descriptor, aggPtrs ...*export.Aggregator) {
+	switch descriptor.InstrumentKind() {
+	case sdkapi.GaugeObserverInstrumentKind:
+		lastValueAggs(aggPtrs)
+	case sdkapi.HistogramInstrumentKind:
+		aggs := minmaxsumcount.New(len(aggPtrs), descriptor)
+		for i := range aggPtrs {
+			*aggPtrs[i] = &aggs[i]
+		}
+	default:
+		sumAggs(aggPtrs)
+	}
+}
+
+func (selectorExact) AggregatorFor(descriptor *sdkapi.Descriptor, aggPtrs ...*export.Aggregator) {
+	switch descriptor.InstrumentKind() {
+	case sdkapi.GaugeObserverInstrumentKind:
+		lastValueAggs(aggPtrs)
+	case sdkapi.HistogramInstrumentKind:
+		aggs := exact.New(len(aggPtrs))
+		for i := range aggPtrs {
+			*aggPtrs[i] = &aggs[i]
+		}
+	default:
+		sumAggs(aggPtrs)
+	}
+}
+
+func (s selectorHistogram) AggregatorFor(descriptor *sdkapi.Descriptor, aggPtrs ...*export.Aggregator) {
+	switch descriptor.InstrumentKind() {
+	case sdkapi.GaugeObserverInstrumentKind:
+		lastValueAggs(aggPtrs)
+	case sdkapi.HistogramInstrumentKind:
+		aggs := histogram.New(len(aggPtrs), descriptor, s.options...)
+		for i := range aggPtrs {
+			*aggPtrs[i] = &aggs[i]
+		}
+	default:
+		sumAggs(aggPtrs)
+	}
+}