@@ -382,19 +382,20 @@ type HistogramOpts struct {
382382 Buckets []float64
383383
384384 // If SparseBucketsFactor is greater than one, sparse buckets are used
385- // (in addition to the regular buckets, if defined above). Sparse
386- // buckets are exponential buckets covering the whole float64 range
387- // (with the exception of the “zero” bucket, see
388- // SparseBucketsZeroThreshold below). From any one bucket to the next,
389- // the width of the bucket grows by a constant factor.
390- // SparseBucketsFactor provides an upper bound for this factor
391- // (exception see below). The smaller SparseBucketsFactor, the more
392- // buckets will be used and thus the more costly the histogram will
393- // become. A generally good trade-off between cost and accuracy is a
394- // value of 1.1 (each bucket is at most 10% wider than the previous
395- // one), which will result in each power of two divided into 8 buckets
396- // (e.g. there will be 8 buckets between 1 and 2, same as between 2 and
397- // 4, and 4 and 8, etc.).
385+ // (in addition to the regular buckets, if defined above). A histogram
386+ // with sparse buckets will be ingested as a native histogram by a
387+ // Prometheus server with that feature enable. Sparse buckets are
388+ // exponential buckets covering the whole float64 range (with the
389+ // exception of the “zero” bucket, see SparseBucketsZeroThreshold
390+ // below). From any one bucket to the next, the width of the bucket
391+ // grows by a constant factor. SparseBucketsFactor provides an upper
392+ // bound for this factor (exception see below). The smaller
393+ // SparseBucketsFactor, the more buckets will be used and thus the more
394+ // costly the histogram will become. A generally good trade-off between
395+ // cost and accuracy is a value of 1.1 (each bucket is at most 10% wider
396+ // than the previous one), which will result in each power of two
397+ // divided into 8 buckets (e.g. there will be 8 buckets between 1 and 2,
398+ // same as between 2 and 4, and 4 and 8, etc.).
398399 //
399400 // Details about the actually used factor: The factor is calculated as
400401 // 2^(2^n), where n is an integer number between (and including) -8 and
@@ -723,18 +724,18 @@ func (h *histogram) Write(out *dto.Metric) error {
723724 his .Bucket = append (his .Bucket , b )
724725 }
725726 if h .sparseSchema > math .MinInt32 {
726- his .SbZeroThreshold = proto .Float64 (math .Float64frombits (atomic .LoadUint64 (& coldCounts .sparseZeroThresholdBits )))
727- his .SbSchema = proto .Int32 (atomic .LoadInt32 (& coldCounts .sparseSchema ))
727+ his .ZeroThreshold = proto .Float64 (math .Float64frombits (atomic .LoadUint64 (& coldCounts .sparseZeroThresholdBits )))
728+ his .Schema = proto .Int32 (atomic .LoadInt32 (& coldCounts .sparseSchema ))
728729 zeroBucket := atomic .LoadUint64 (& coldCounts .sparseZeroBucket )
729730
730731 defer func () {
731732 coldCounts .sparseBucketsPositive .Range (addAndReset (& hotCounts .sparseBucketsPositive , & hotCounts .sparseBucketsNumber ))
732733 coldCounts .sparseBucketsNegative .Range (addAndReset (& hotCounts .sparseBucketsNegative , & hotCounts .sparseBucketsNumber ))
733734 }()
734735
735- his .SbZeroCount = proto .Uint64 (zeroBucket )
736- his .SbNegative = makeSparseBuckets (& coldCounts .sparseBucketsNegative )
737- his .SbPositive = makeSparseBuckets (& coldCounts .sparseBucketsPositive )
736+ his .ZeroCount = proto .Uint64 (zeroBucket )
737+ his .NegativeSpan , his . NegativeDelta = makeSparseBuckets (& coldCounts .sparseBucketsNegative )
738+ his .PositiveSpan , his . PositiveDelta = makeSparseBuckets (& coldCounts .sparseBucketsPositive )
738739 }
739740 addAndResetCounts (hotCounts , coldCounts )
740741 return nil
@@ -1235,7 +1236,7 @@ func pickSparseSchema(bucketFactor float64) int32 {
12351236 }
12361237}
12371238
1238- func makeSparseBuckets (buckets * sync.Map ) * dto.SparseBuckets {
1239+ func makeSparseBuckets (buckets * sync.Map ) ([] * dto.BucketSpan , [] int64 ) {
12391240 var ii []int
12401241 buckets .Range (func (k , v interface {}) bool {
12411242 ii = append (ii , k .(int ))
@@ -1244,16 +1245,19 @@ func makeSparseBuckets(buckets *sync.Map) *dto.SparseBuckets {
12441245 sort .Ints (ii )
12451246
12461247 if len (ii ) == 0 {
1247- return nil
1248+ return nil , nil
12481249 }
12491250
1250- sbs := dto.SparseBuckets {}
1251- var prevCount int64
1252- var nextI int
1251+ var (
1252+ spans []* dto.BucketSpan
1253+ deltas []int64
1254+ prevCount int64
1255+ nextI int
1256+ )
12531257
12541258 appendDelta := func (count int64 ) {
1255- * sbs . Span [len (sbs . Span )- 1 ].Length ++
1256- sbs . Delta = append (sbs . Delta , count - prevCount )
1259+ * spans [len (spans )- 1 ].Length ++
1260+ deltas = append (deltas , count - prevCount )
12571261 prevCount = count
12581262 }
12591263
@@ -1270,7 +1274,7 @@ func makeSparseBuckets(buckets *sync.Map) *dto.SparseBuckets {
12701274 // We have to create a new span, either because we are
12711275 // at the very beginning, or because we have found a gap
12721276 // of more than two buckets.
1273- sbs . Span = append (sbs . Span , & dto.SparseBuckets_Span {
1277+ spans = append (spans , & dto.BucketSpan {
12741278 Offset : proto .Int32 (iDelta ),
12751279 Length : proto .Uint32 (0 ),
12761280 })
@@ -1284,7 +1288,7 @@ func makeSparseBuckets(buckets *sync.Map) *dto.SparseBuckets {
12841288 appendDelta (count )
12851289 nextI = i + 1
12861290 }
1287- return & sbs
1291+ return spans , deltas
12881292}
12891293
12901294// addToSparseBucket increments the sparse bucket at key by the provided
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