[chore][exporter/sumologic]: add deduplicateErrors and decomposeHistograms functions (#32316)

**Description:**

Adds files from Sumo Logic Distribution for OpenTelemetry which are new
in order to simplify review and make simpler to move the whole
component.

This PR is made to simplify #32315

**Link to tracking Issue:**

#31479

**Testing:**

Unit Tests, also this code is use by our customers and internally. It is
not used by now by the component, but will be when migration will be
finished

**Documentation:** N/A

Signed-off-by: Dominik Rosiek <[email protected]>

Author: sumo-drosiek

exporter/sumologicexporter/deduplicate_errors.go

@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package sumologicexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/sumologicexporter"
+
+import "fmt"
+
+// deduplicateErrors replaces duplicate instances of the same error in a slice
+// with a single error containing the number of times it occurred added as a suffix.
+// For example, three occurrences of "error: 502 Bad Gateway"
+// are replaced with a single instance of "error: 502 Bad Gateway (x3)".
+func deduplicateErrors(errs []error) []error {
+	if len(errs) < 2 {
+		return errs
+	}
+
+	errorsWithCounts := []errorWithCount{}
+	for _, err := range errs {
+		found := false
+		for i := range errorsWithCounts {
+			if errorsWithCounts[i].err.Error() == err.Error() {
+				found = true
+				errorsWithCounts[i].count++
+				break
+			}
+		}
+		if !found {
+			errorsWithCounts = append(errorsWithCounts, errorWithCount{
+				err:   err,
+				count: 1,
+			})
+		}
+	}
+
+	var uniqueErrors []error
+	for _, errorWithCount := range errorsWithCounts {
+		if errorWithCount.count == 1 {
+			uniqueErrors = append(uniqueErrors, errorWithCount.err)
+		} else {
+			uniqueErrors = append(uniqueErrors, fmt.Errorf("%s (x%d)", errorWithCount.err.Error(), errorWithCount.count))
+		}
+	}
+	return uniqueErrors
+}
+
+type errorWithCount struct {
+	err   error
+	count int
+}

exporter/sumologicexporter/deduplicate_errors_test.go

@@ -0,0 +1,58 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package sumologicexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/sumologicexporter"
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDeduplicateErrors(t *testing.T) {
+	testCases := []struct {
+		name     string
+		errs     []error
+		expected []error
+	}{
+		{
+			name:     "nil is returned as nil",
+			errs:     nil,
+			expected: nil,
+		},
+		{
+			name: "single error is returned as-is",
+			errs: []error{
+				errors.New("Single error"),
+			},
+			expected: []error{
+				errors.New("Single error"),
+			},
+		},
+		{
+			name: "duplicates are removed",
+			errs: []error{
+				errors.New("failed sending data: 502 Bad Gateway"),
+				errors.New("failed sending data: 400 Bad Request"),
+				errors.New("failed sending data: 502 Bad Gateway"),
+				errors.New("failed sending data: 400 Bad Request"),
+				errors.New("failed sending data: 400 Bad Request"),
+				errors.New("failed sending data: 400 Bad Request"),
+				errors.New("failed sending data: 504 Gateway Timeout"),
+				errors.New("failed sending data: 502 Bad Gateway"),
+			},
+			expected: []error{
+				errors.New("failed sending data: 502 Bad Gateway (x3)"),
+				errors.New("failed sending data: 400 Bad Request (x4)"),
+				errors.New("failed sending data: 504 Gateway Timeout"),
+			},
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			assert.Equal(t, testCase.expected, deduplicateErrors(testCase.errs))
+		})
+	}
+}

exporter/sumologicexporter/otlp.go

@@ -0,0 +1,149 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package sumologicexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/sumologicexporter"
+
+import (
+	"math"
+
+	"go.opentelemetry.io/collector/pdata/pmetric"
+)
+
+// decomposeHistograms decomposes any histograms present in the metric data into individual Sums and Gauges
+// This is a noop if no Histograms are present, but otherwise makes a copy of the whole structure
+// This exists because Sumo doesn't support OTLP histograms yet, and has the same semantics as the conversion to Prometheus format in prometheus_formatter.go
+func decomposeHistograms(md pmetric.Metrics) pmetric.Metrics {
+	// short circuit and do nothing if no Histograms are present
+	foundHistogram := false
+outer:
+	for i := 0; i < md.ResourceMetrics().Len(); i++ {
+		resourceMetric := md.ResourceMetrics().At(i)
+		for j := 0; j < resourceMetric.ScopeMetrics().Len(); j++ {
+			scopeMetric := resourceMetric.ScopeMetrics().At(j)
+			for k := 0; k < scopeMetric.Metrics().Len(); k++ {
+				foundHistogram = scopeMetric.Metrics().At(k).Type() == pmetric.MetricTypeHistogram
+				if foundHistogram {
+					break outer
+				}
+			}
+		}
+	}
+	if !foundHistogram {
+		return md
+	}
+
+	decomposed := pmetric.NewMetrics()
+	md.CopyTo(decomposed)
+
+	for i := 0; i < decomposed.ResourceMetrics().Len(); i++ {
+		resourceMetric := decomposed.ResourceMetrics().At(i)
+		for j := 0; j < resourceMetric.ScopeMetrics().Len(); j++ {
+			metrics := resourceMetric.ScopeMetrics().At(j).Metrics()
+			for k := 0; k < metrics.Len(); k++ {
+				metric := metrics.At(k)
+				if metric.Type() == pmetric.MetricTypeHistogram {
+					decomposedHistogram := decomposeHistogram(metric)
+					decomposedHistogram.MoveAndAppendTo(metrics)
+				}
+			}
+			metrics.RemoveIf(func(m pmetric.Metric) bool { return m.Type() == pmetric.MetricTypeHistogram })
+		}
+	}
+
+	return decomposed
+}
+
+// decomposeHistogram decomposes a single Histogram metric into individual metrics for count, bucket and sum
+// non-Histograms give an empty slice as output
+func decomposeHistogram(metric pmetric.Metric) pmetric.MetricSlice {
+	output := pmetric.NewMetricSlice()
+	if metric.Type() != pmetric.MetricTypeHistogram {
+		return output
+	}
+
+	getHistogramSumMetric(metric).MoveTo(output.AppendEmpty())
+	getHistogramCountMetric(metric).MoveTo(output.AppendEmpty())
+	getHistogramBucketsMetric(metric).MoveTo(output.AppendEmpty())
+
+	return output
+}
+
+func getHistogramBucketsMetric(metric pmetric.Metric) pmetric.Metric {
+	histogram := metric.Histogram()
+
+	bucketsMetric := pmetric.NewMetric()
+	bucketsMetric.SetName(metric.Name() + "_bucket")
+	bucketsMetric.SetDescription(metric.Description())
+	bucketsMetric.SetUnit(metric.Unit())
+	bucketsMetric.SetEmptyGauge()
+	bucketsDatapoints := bucketsMetric.Gauge().DataPoints()
+
+	for i := 0; i < histogram.DataPoints().Len(); i++ {
+		histogramDataPoint := histogram.DataPoints().At(i)
+		histogramBounds := histogramDataPoint.ExplicitBounds()
+		var cumulative uint64
+
+		for j := 0; j < histogramBounds.Len(); j++ {
+			bucketDataPoint := bucketsDatapoints.AppendEmpty()
+			bound := histogramBounds.At(j)
+			histogramDataPoint.Attributes().CopyTo(bucketDataPoint.Attributes())
+			bucketDataPoint.Attributes().PutDouble(prometheusLeTag, bound)
+			bucketDataPoint.SetStartTimestamp(histogramDataPoint.StartTimestamp())
+			bucketDataPoint.SetTimestamp(histogramDataPoint.Timestamp())
+			cumulative += histogramDataPoint.BucketCounts().At(j)
+			bucketDataPoint.SetIntValue(int64(cumulative))
+		}
+
+		// need to add one more bucket at +Inf
+		bucketDataPoint := bucketsDatapoints.AppendEmpty()
+		histogramDataPoint.Attributes().CopyTo(bucketDataPoint.Attributes())
+		bucketDataPoint.Attributes().PutDouble(prometheusLeTag, math.Inf(1))
+		bucketDataPoint.SetStartTimestamp(histogramDataPoint.StartTimestamp())
+		bucketDataPoint.SetTimestamp(histogramDataPoint.Timestamp())
+		cumulative += histogramDataPoint.BucketCounts().At(histogramDataPoint.ExplicitBounds().Len())
+		bucketDataPoint.SetIntValue(int64(cumulative))
+	}
+	return bucketsMetric
+}
+
+func getHistogramSumMetric(metric pmetric.Metric) pmetric.Metric {
+	histogram := metric.Histogram()
+
+	sumMetric := pmetric.NewMetric()
+	sumMetric.SetName(metric.Name() + "_sum")
+	sumMetric.SetDescription(metric.Description())
+	sumMetric.SetUnit(metric.Unit())
+	sumMetric.SetEmptyGauge()
+	sumDataPoints := sumMetric.Gauge().DataPoints()
+
+	for i := 0; i < histogram.DataPoints().Len(); i++ {
+		histogramDataPoint := histogram.DataPoints().At(i)
+		sumDataPoint := sumDataPoints.AppendEmpty()
+		histogramDataPoint.Attributes().CopyTo(sumDataPoint.Attributes())
+		sumDataPoint.SetStartTimestamp(histogramDataPoint.StartTimestamp())
+		sumDataPoint.SetTimestamp(histogramDataPoint.Timestamp())
+		sumDataPoint.SetDoubleValue(histogramDataPoint.Sum())
+	}
+	return sumMetric
+}
+
+func getHistogramCountMetric(metric pmetric.Metric) pmetric.Metric {
+	histogram := metric.Histogram()
+
+	countMetric := pmetric.NewMetric()
+	countMetric.SetName(metric.Name() + "_count")
+	countMetric.SetDescription(metric.Description())
+	countMetric.SetUnit(metric.Unit())
+	countMetric.SetEmptyGauge()
+	countDataPoints := countMetric.Gauge().DataPoints()
+
+	for i := 0; i < histogram.DataPoints().Len(); i++ {
+		histogramDataPoint := histogram.DataPoints().At(i)
+		countDataPoint := countDataPoints.AppendEmpty()
+		histogramDataPoint.Attributes().CopyTo(countDataPoint.Attributes())
+		countDataPoint.SetStartTimestamp(histogramDataPoint.StartTimestamp())
+		countDataPoint.SetTimestamp(histogramDataPoint.Timestamp())
+		countDataPoint.SetIntValue(int64(histogramDataPoint.Count()))
+	}
+	return countMetric
+}