[chore] [exporter/elasticsearch] Extract mapping hints into an intern…

…al elasticsearch module (#37235)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This is the first (or the first after several attempts canceled for
various reasons) attempt to split data serialization/encoding into
multiple packages, so we can separate the module per encoding type.

See
#37207
as the previous attempt which was canceled due to another refactoring
that required more ground splitting first.

---------

Co-authored-by: Tim Rühsen <tim.ruehsen@gmx.de>

exporter/elasticsearchexporter/internal/elasticsearch/mapping_hint.go

@@ -0,0 +1,44 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package elasticsearch // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/elasticsearch"
+
+import (
+	"slices"
+
+	"go.opentelemetry.io/collector/pdata/pcommon"
+)
+
+const (
+	MappingHintsAttrKey = "elasticsearch.mapping.hints"
+)
+
+type MappingHint string
+
+const (
+	HintAggregateMetricDouble MappingHint = "aggregate_metric_double"
+	HintDocCount              MappingHint = "_doc_count"
+)
+
+type MappingHintGetter struct {
+	hints []MappingHint
+}
+
+// NewMappingHintGetter creates a new MappingHintGetter
+func NewMappingHintGetter(attr pcommon.Map) (g MappingHintGetter) {
+	v, ok := attr.Get(MappingHintsAttrKey)
+	if !ok || v.Type() != pcommon.ValueTypeSlice {
+		return
+	}
+	slice := v.Slice()
+	g.hints = slices.Grow(g.hints, slice.Len())
+	for i := range slice.Len() {
+		g.hints = append(g.hints, MappingHint(slice.At(i).Str()))
+	}
+	return
+}
+
+// HasMappingHint checks whether the getter contains the requested mapping hint
+func (g MappingHintGetter) HasMappingHint(hint MappingHint) bool {
+	return slices.Contains(g.hints, hint)
+}

exporter/elasticsearchexporter/mapping_hint_test.go → exporter/elasticsearchexporter/internal/elasticsearch/mapping_hint_test.go

@@ -1,7 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package elasticsearchexporter
+package elasticsearch
 
 import (
 	"testing"
@@ -14,74 +14,74 @@ func TestHasHint(t *testing.T) {
 	tests := []struct {
 		name      string
 		attrsFunc func() pcommon.Map
-		hint      mappingHint
+		hint      MappingHint
 		want      bool
 	}{
 		{
 			name:      "empty map",
 			attrsFunc: pcommon.NewMap,
-			hint:      hintAggregateMetricDouble,
+			hint:      HintAggregateMetricDouble,
 			want:      false,
 		},
 		{
 			name: "bad type",
 			attrsFunc: func() pcommon.Map {
 				m := pcommon.NewMap()
-				m.PutBool(mappingHintsAttrKey, true)
+				m.PutBool(MappingHintsAttrKey, true)
 				return m
 			},
-			hint: hintAggregateMetricDouble,
+			hint: HintAggregateMetricDouble,
 			want: false,
 		},
 		{
 			name: "bad inner type",
 			attrsFunc: func() pcommon.Map {
 				m := pcommon.NewMap()
-				s := m.PutEmptySlice(mappingHintsAttrKey)
+				s := m.PutEmptySlice(MappingHintsAttrKey)
 				s.AppendEmpty().SetBool(true)
 				return m
 			},
-			hint: hintAggregateMetricDouble,
+			hint: HintAggregateMetricDouble,
 			want: false,
 		},
 		{
 			name: "hit",
 			attrsFunc: func() pcommon.Map {
 				m := pcommon.NewMap()
-				s := m.PutEmptySlice(mappingHintsAttrKey)
-				s.AppendEmpty().SetStr(string(hintAggregateMetricDouble))
+				s := m.PutEmptySlice(MappingHintsAttrKey)
+				s.AppendEmpty().SetStr(string(HintAggregateMetricDouble))
 				return m
 			},
-			hint: hintAggregateMetricDouble,
+			hint: HintAggregateMetricDouble,
 			want: true,
 		},
 		{
 			name: "hit 2nd",
 			attrsFunc: func() pcommon.Map {
 				m := pcommon.NewMap()
-				s := m.PutEmptySlice(mappingHintsAttrKey)
-				s.AppendEmpty().SetStr(string(hintDocCount))
-				s.AppendEmpty().SetStr(string(hintAggregateMetricDouble))
+				s := m.PutEmptySlice(MappingHintsAttrKey)
+				s.AppendEmpty().SetStr(string(HintDocCount))
+				s.AppendEmpty().SetStr(string(HintAggregateMetricDouble))
 				return m
 			},
-			hint: hintAggregateMetricDouble,
+			hint: HintAggregateMetricDouble,
 			want: true,
 		},
 		{
 			name: "miss",
 			attrsFunc: func() pcommon.Map {
 				m := pcommon.NewMap()
-				s := m.PutEmptySlice(mappingHintsAttrKey)
-				s.AppendEmpty().SetStr(string(hintDocCount))
+				s := m.PutEmptySlice(MappingHintsAttrKey)
+				s.AppendEmpty().SetStr(string(HintDocCount))
 				return m
 			},
-			hint: hintAggregateMetricDouble,
+			hint: HintAggregateMetricDouble,
 			want: false,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			assert.Equal(t, tt.want, newMappingHintGetter(tt.attrsFunc()).HasMappingHint(tt.hint))
+			assert.Equal(t, tt.want, NewMappingHintGetter(tt.attrsFunc()).HasMappingHint(tt.hint))
 		})
 	}
 }

exporter/elasticsearchexporter/model.go

@@ -21,6 +21,7 @@ import (
 	"go.opentelemetry.io/collector/pdata/ptrace"
 	semconv "go.opentelemetry.io/collector/semconv/v1.22.0"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/elasticsearch"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/exphistogram"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/objmodel"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal/traceutil"
@@ -101,7 +102,7 @@ type dataPoint interface {
 	Value() (pcommon.Value, error)
 	DynamicTemplate(pmetric.Metric) string
 	DocCount() uint64
-	HasMappingHint(mappingHint) bool
+	HasMappingHint(elasticsearch.MappingHint) bool
 	Metric() pmetric.Metric
 }
 
@@ -263,12 +264,12 @@ func (m *encodeModel) encodeMetrics(resource pcommon.Resource, resourceSchemaURL
 
 type summaryDataPoint struct {
 	pmetric.SummaryDataPoint
-	mappingHintGetter
+	elasticsearch.MappingHintGetter
 	metric pmetric.Metric
 }
 
 func newSummaryDataPoint(metric pmetric.Metric, dp pmetric.SummaryDataPoint) summaryDataPoint {
-	return summaryDataPoint{SummaryDataPoint: dp, mappingHintGetter: newMappingHintGetter(dp.Attributes()), metric: metric}
+	return summaryDataPoint{SummaryDataPoint: dp, MappingHintGetter: elasticsearch.NewMappingHintGetter(dp.Attributes()), metric: metric}
 }
 
 func (dp summaryDataPoint) Value() (pcommon.Value, error) {
@@ -295,16 +296,16 @@ func (dp summaryDataPoint) Metric() pmetric.Metric {
 
 type exponentialHistogramDataPoint struct {
 	pmetric.ExponentialHistogramDataPoint
-	mappingHintGetter
+	elasticsearch.MappingHintGetter
 	metric pmetric.Metric
 }
 
 func newExponentialHistogramDataPoint(metric pmetric.Metric, dp pmetric.ExponentialHistogramDataPoint) exponentialHistogramDataPoint {
-	return exponentialHistogramDataPoint{ExponentialHistogramDataPoint: dp, mappingHintGetter: newMappingHintGetter(dp.Attributes()), metric: metric}
+	return exponentialHistogramDataPoint{ExponentialHistogramDataPoint: dp, MappingHintGetter: elasticsearch.NewMappingHintGetter(dp.Attributes()), metric: metric}
 }
 
 func (dp exponentialHistogramDataPoint) Value() (pcommon.Value, error) {
-	if dp.HasMappingHint(hintAggregateMetricDouble) {
+	if dp.HasMappingHint(elasticsearch.HintAggregateMetricDouble) {
 		vm := pcommon.NewValueMap()
 		m := vm.Map()
 		m.PutDouble("sum", dp.Sum())
@@ -331,7 +332,7 @@ func (dp exponentialHistogramDataPoint) Value() (pcommon.Value, error) {
 }
 
 func (dp exponentialHistogramDataPoint) DynamicTemplate(_ pmetric.Metric) string {
-	if dp.HasMappingHint(hintAggregateMetricDouble) {
+	if dp.HasMappingHint(elasticsearch.HintAggregateMetricDouble) {
 		return "summary"
 	}
 	return "histogram"
@@ -347,16 +348,16 @@ func (dp exponentialHistogramDataPoint) Metric() pmetric.Metric {
 
 type histogramDataPoint struct {
 	pmetric.HistogramDataPoint
-	mappingHintGetter
+	elasticsearch.MappingHintGetter
 	metric pmetric.Metric
 }
 
 func newHistogramDataPoint(metric pmetric.Metric, dp pmetric.HistogramDataPoint) histogramDataPoint {
-	return histogramDataPoint{HistogramDataPoint: dp, mappingHintGetter: newMappingHintGetter(dp.Attributes()), metric: metric}
+	return histogramDataPoint{HistogramDataPoint: dp, MappingHintGetter: elasticsearch.NewMappingHintGetter(dp.Attributes()), metric: metric}
 }
 
 func (dp histogramDataPoint) Value() (pcommon.Value, error) {
-	if dp.HasMappingHint(hintAggregateMetricDouble) {
+	if dp.HasMappingHint(elasticsearch.HintAggregateMetricDouble) {
 		vm := pcommon.NewValueMap()
 		m := vm.Map()
 		m.PutDouble("sum", dp.Sum())
@@ -367,7 +368,7 @@ func (dp histogramDataPoint) Value() (pcommon.Value, error) {
 }
 
 func (dp histogramDataPoint) DynamicTemplate(_ pmetric.Metric) string {
-	if dp.HasMappingHint(hintAggregateMetricDouble) {
+	if dp.HasMappingHint(elasticsearch.HintAggregateMetricDouble) {
 		return "summary"
 	}
 	return "histogram"
@@ -431,12 +432,12 @@ func histogramToValue(dp pmetric.HistogramDataPoint) (pcommon.Value, error) {
 
 type numberDataPoint struct {
 	pmetric.NumberDataPoint
-	mappingHintGetter
+	elasticsearch.MappingHintGetter
 	metric pmetric.Metric
 }
 
 func newNumberDataPoint(metric pmetric.Metric, dp pmetric.NumberDataPoint) numberDataPoint {
-	return numberDataPoint{NumberDataPoint: dp, mappingHintGetter: newMappingHintGetter(dp.Attributes()), metric: metric}
+	return numberDataPoint{NumberDataPoint: dp, MappingHintGetter: elasticsearch.NewMappingHintGetter(dp.Attributes()), metric: metric}
 }
 
 func (dp numberDataPoint) Value() (pcommon.Value, error) {
@@ -724,7 +725,7 @@ func metricOTelHash(dp dataPoint, unit string) uint32 {
 
 	hasher.Write([]byte(unit))
 
-	mapHashExcludeReservedAttrs(hasher, dp.Attributes(), mappingHintsAttrKey)
+	mapHashExcludeReservedAttrs(hasher, dp.Attributes(), elasticsearch.MappingHintsAttrKey)
 
 	return hasher.Sum32()
 }

exporter/elasticsearchexporter/pdata_serializer.go

@@ -15,6 +15,8 @@ import (
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/plog"
 	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/elasticsearch"
 )
 
 const tsLayout = "2006-01-02T15:04:05.000000000Z"
@@ -68,7 +70,7 @@ func serializeDataPoints(v *json.Visitor, dataPoints []dataPoint, validationErro
 		// TODO here's potential for more optimization by directly serializing the value instead of allocating a pcommon.Value
 		//  the tradeoff is that this would imply a duplicated logic for the ECS mode
 		value, err := dp.Value()
-		if dp.HasMappingHint(hintDocCount) {
+		if dp.HasMappingHint(elasticsearch.HintDocCount) {
 			docCount = dp.DocCount()
 		}
 		if err != nil {
@@ -296,7 +298,7 @@ func writeAttributes(v *json.Visitor, attributes pcommon.Map, stringifyMapValues
 	_ = v.OnObjectStart(-1, structform.AnyType)
 	attributes.Range(func(k string, val pcommon.Value) bool {
 		switch k {
-		case dataStreamType, dataStreamDataset, dataStreamNamespace, mappingHintsAttrKey:
+		case dataStreamType, dataStreamDataset, dataStreamNamespace, elasticsearch.MappingHintsAttrKey:
 			return true
 		}
 		if isGeoAttribute(k, val) {