| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package metrix |
| 4 | |
| 5 | import ( |
| 6 | "fmt" |
| 7 | "math" |
| 8 | "sort" |
| 9 | "strconv" |
| 10 | ) |
| 11 | |
| 12 | const HistogramBucketLabel = "le" |
| 13 | |
| 14 | // snapshotHistogramInstrument writes sampled full histogram points. |
| 15 | type snapshotHistogramInstrument struct { |
| 16 | backend meterBackend |
| 17 | desc *instrumentDescriptor |
| 18 | scope HostScope |
| 19 | base []LabelSet |
| 20 | } |
| 21 | |
| 22 | // statefulHistogramInstrument writes observed samples into maintained histogram state. |
| 23 | type statefulHistogramInstrument struct { |
| 24 | backend meterBackend |
| 25 | desc *instrumentDescriptor |
| 26 | scope HostScope |
| 27 | base []LabelSet |
| 28 | } |
| 29 | |
| 30 | // stagedHistogram holds one in-cycle histogram sample for a single series identity. |
| 31 | type stagedHistogram struct { |
| 32 | key string |
| 33 | name string |
| 34 | hostScopeKey string |
| 35 | hostScope HostScope |
| 36 | labels []Label |
| 37 | labelsKey string |
| 38 | desc *instrumentDescriptor |
| 39 | bounds []float64 |
| 40 | count SampleValue |
| 41 | sum SampleValue |
| 42 | cumulative []SampleValue |
| 43 | } |
| 44 | |
| 45 | // Histogram declares or reuses a snapshot histogram under this meter. |
| 46 | func (m *snapshotMeter) Histogram(name string, opts ...InstrumentOption) SnapshotHistogram { |
| 47 | desc, err := m.backend.registerInstrument(metricName(m.prefix, name), kindHistogram, modeSnapshot, opts...) |
| 48 | if err != nil { |
| 49 | panic(err) |
| 50 | } |
| 51 | return &snapshotHistogramInstrument{ |
| 52 | backend: m.backend, |
| 53 | desc: desc, |
| 54 | scope: m.scope, |
| 55 | base: appendLabelSets(m.sets, nil), |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | // Histogram declares or reuses a stateful histogram under this meter. |
| 60 | func (m *statefulMeter) Histogram(name string, opts ...InstrumentOption) StatefulHistogram { |
| 61 | desc, err := m.backend.registerInstrument(metricName(m.prefix, name), kindHistogram, modeStateful, opts...) |
| 62 | if err != nil { |
| 63 | panic(err) |
| 64 | } |
| 65 | return &statefulHistogramInstrument{ |
| 66 | backend: m.backend, |
| 67 | desc: desc, |
| 68 | scope: m.scope, |
| 69 | base: appendLabelSets(m.sets, nil), |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | // ObservePoint writes one full histogram point for this collect cycle. |
| 74 | func (h *snapshotHistogramInstrument) ObservePoint(p HistogramPoint, labels ...LabelSet) { |
| 75 | h.backend.recordHistogramObservePoint(h.desc, h.scope, p, appendLabelSets(h.base, labels)) |
| 76 | } |
| 77 | |
| 78 | // Observe adds one sample to a stateful histogram for this collect cycle. |
| 79 | func (h *statefulHistogramInstrument) Observe(v SampleValue, labels ...LabelSet) { |
| 80 | h.backend.recordHistogramObserve(h.desc, h.scope, v, appendLabelSets(h.base, labels)) |
| 81 | } |
| 82 | |
| 83 | // recordHistogramObservePoint writes one full histogram point into the active frame. |
| 84 | func (c *storeCore) recordHistogramObservePoint(desc *instrumentDescriptor, scope HostScope, point HistogramPoint, sets []LabelSet) { |
| 85 | c.mu.Lock() |
| 86 | defer c.mu.Unlock() |
| 87 | |
| 88 | if c.active == nil { |
| 89 | panic(errCycleInactive) |
| 90 | } |
| 91 | |
| 92 | labels, labelsKey, err := labelsFromSet(sets, c) |
| 93 | if err != nil { |
| 94 | panic(err) |
| 95 | } |
| 96 | if labelsContainKey(labels, HistogramBucketLabel) { |
| 97 | panic(errHistogramLabelKey) |
| 98 | } |
| 99 | scope, ok := c.prepareHostScopeForWriteLocked(scope) |
| 100 | if !ok { |
| 101 | return |
| 102 | } |
| 103 | |
| 104 | schema := desc.histogram |
| 105 | if schema == nil { |
| 106 | // For snapshot histograms without explicit bounds, validate against |
| 107 | // previously captured family schema (if available). |
| 108 | schema = c.snapshotHistogramSchema[desc.name] |
| 109 | } |
| 110 | bounds, count, sum, cumulative := normalizeHistogramPoint(point, schema) |
| 111 | |
| 112 | key := makeSeriesKey(scope.ScopeKey, desc.name, labelsKey) |
| 113 | entry, ok := c.active.histograms[key] |
| 114 | if !ok { |
| 115 | entry = &stagedHistogram{ |
| 116 | key: key, |
| 117 | name: desc.name, |
| 118 | hostScopeKey: scope.ScopeKey, |
| 119 | hostScope: scope, |
| 120 | labels: labels, |
| 121 | labelsKey: labelsKey, |
| 122 | desc: desc, |
| 123 | } |
| 124 | c.active.histograms[key] = entry |
| 125 | } |
| 126 | if len(entry.bounds) > 0 && !equalHistogramBounds(entry.bounds, bounds) { |
| 127 | panic("metrix: histogram point schema mismatch within cycle") |
| 128 | } |
| 129 | entry.bounds = append(entry.bounds[:0], bounds...) |
| 130 | entry.count = count |
| 131 | entry.sum = sum |
| 132 | entry.cumulative = append(entry.cumulative[:0], cumulative...) |
| 133 | } |
| 134 | |
| 135 | // recordHistogramObserve adds one sample to a stateful histogram in the active frame. |
| 136 | func (c *storeCore) recordHistogramObserve(desc *instrumentDescriptor, scope HostScope, value SampleValue, sets []LabelSet) { |
| 137 | mustFiniteSample(value) |
| 138 | |
| 139 | c.mu.Lock() |
| 140 | defer c.mu.Unlock() |
| 141 | |
| 142 | if c.active == nil { |
| 143 | panic(errCycleInactive) |
| 144 | } |
| 145 | |
| 146 | schema := desc.histogram |
| 147 | if schema == nil || len(schema.bounds) == 0 { |
| 148 | panic(errHistogramBounds) |
| 149 | } |
| 150 | |
| 151 | labels, labelsKey, err := labelsFromSet(sets, c) |
| 152 | if err != nil { |
| 153 | panic(err) |
| 154 | } |
| 155 | if labelsContainKey(labels, HistogramBucketLabel) { |
| 156 | panic(errHistogramLabelKey) |
| 157 | } |
| 158 | scope, ok := c.prepareHostScopeForWriteLocked(scope) |
| 159 | if !ok { |
| 160 | return |
| 161 | } |
| 162 | |
| 163 | key := makeSeriesKey(scope.ScopeKey, desc.name, labelsKey) |
| 164 | entry, ok := c.active.histograms[key] |
| 165 | if !ok { |
| 166 | entry = &stagedHistogram{ |
| 167 | key: key, |
| 168 | name: desc.name, |
| 169 | hostScopeKey: scope.ScopeKey, |
| 170 | hostScope: scope, |
| 171 | labels: labels, |
| 172 | labelsKey: labelsKey, |
| 173 | desc: desc, |
| 174 | bounds: append([]float64(nil), schema.bounds...), |
| 175 | cumulative: make([]SampleValue, len(schema.bounds)), |
| 176 | } |
| 177 | if desc.window == WindowCumulative { |
| 178 | if existing := c.snapshot.Load().series[key]; existing != nil && existing.desc != nil && existing.desc.kind == kindHistogram { |
| 179 | entry.count = existing.histogramCount |
| 180 | entry.sum = existing.histogramSum |
| 181 | entry.cumulative = append(entry.cumulative[:0], existing.histogramCumulative...) |
| 182 | if len(entry.cumulative) < len(schema.bounds) { |
| 183 | entry.cumulative = append(entry.cumulative, make([]SampleValue, len(schema.bounds)-len(entry.cumulative))...) |
| 184 | } |
| 185 | } |
| 186 | } |
| 187 | c.active.histograms[key] = entry |
| 188 | } |
| 189 | |
| 190 | idx := findHistogramBucket(schema.bounds, value) |
| 191 | if idx < len(entry.cumulative) { |
| 192 | for i := idx; i < len(entry.cumulative); i++ { |
| 193 | entry.cumulative[i]++ |
| 194 | } |
| 195 | } |
| 196 | entry.count++ |
| 197 | entry.sum += value |
| 198 | } |
| 199 | |
| 200 | func normalizeHistogramPoint(point HistogramPoint, schema *histogramSchema) ([]float64, SampleValue, SampleValue, []SampleValue) { |
| 201 | mustFiniteSample(point.Count) |
| 202 | mustFiniteSample(point.Sum) |
| 203 | |
| 204 | if point.Count < 0 { |
| 205 | panic(fmt.Errorf("%w: negative count", errHistogramPoint)) |
| 206 | } |
| 207 | |
| 208 | bounds := make([]float64, 0, len(point.Buckets)) |
| 209 | cumulative := make([]SampleValue, 0, len(point.Buckets)) |
| 210 | prevBound := math.Inf(-1) |
| 211 | prevCount := SampleValue(0) |
| 212 | for i, b := range point.Buckets { |
| 213 | ub := b.UpperBound |
| 214 | if math.IsNaN(ub) || math.IsInf(ub, -1) { |
| 215 | panic(fmt.Errorf("%w: invalid upper bound", errHistogramPoint)) |
| 216 | } |
| 217 | if math.IsInf(ub, +1) { |
| 218 | if i != len(point.Buckets)-1 { |
| 219 | panic(fmt.Errorf("%w: +Inf bucket must be last", errHistogramPoint)) |
| 220 | } |
| 221 | // +Inf bucket is implicit. |
| 222 | continue |
| 223 | } |
| 224 | if ub <= prevBound { |
| 225 | panic(fmt.Errorf("%w: bounds must be strictly increasing", errHistogramPoint)) |
| 226 | } |
| 227 | if b.CumulativeCount < prevCount { |
| 228 | panic(fmt.Errorf("%w: cumulative bucket counts must be monotonic", errHistogramPoint)) |
| 229 | } |
| 230 | if b.CumulativeCount < 0 { |
| 231 | panic(fmt.Errorf("%w: cumulative bucket counts must be non-negative", errHistogramPoint)) |
| 232 | } |
| 233 | mustFiniteSample(b.CumulativeCount) |
| 234 | bounds = append(bounds, ub) |
| 235 | cumulative = append(cumulative, b.CumulativeCount) |
| 236 | prevBound = ub |
| 237 | prevCount = b.CumulativeCount |
| 238 | } |
| 239 | if len(cumulative) > 0 && cumulative[len(cumulative)-1] > point.Count { |
| 240 | panic(fmt.Errorf("%w: last cumulative bucket exceeds count", errHistogramPoint)) |
| 241 | } |
| 242 | |
| 243 | if schema != nil { |
| 244 | if !equalHistogramBounds(schema.bounds, bounds) { |
| 245 | panic(fmt.Errorf("%w: bucket bounds mismatch", errHistogramPoint)) |
| 246 | } |
| 247 | bounds = append([]float64(nil), schema.bounds...) |
| 248 | } |
| 249 | |
| 250 | return bounds, point.Count, point.Sum, cumulative |
| 251 | } |
| 252 | |
| 253 | // findHistogramBucket returns the index of the bucket for value, or len(bounds) for +Inf. |
| 254 | func findHistogramBucket(bounds []float64, value float64) int { |
| 255 | n := len(bounds) |
| 256 | if n == 0 { |
| 257 | return 0 |
| 258 | } |
| 259 | if value <= bounds[0] { |
| 260 | return 0 |
| 261 | } |
| 262 | if value > bounds[n-1] { |
| 263 | return n |
| 264 | } |
| 265 | if n < 35 { |
| 266 | for i, b := range bounds { |
| 267 | if value <= b { |
| 268 | return i |
| 269 | } |
| 270 | } |
| 271 | return n |
| 272 | } |
| 273 | return sort.SearchFloat64s(bounds, value) |
| 274 | } |
| 275 | |
| 276 | func formatHistogramBucketLabel(v float64) string { |
| 277 | if math.IsInf(v, +1) { |
| 278 | return "+Inf" |
| 279 | } |
| 280 | return strconv.FormatFloat(v, 'g', -1, 64) |
| 281 | } |