quantile: Speed up queries by avoiding creating closures
benchmark old ns/op new ns/op delta
BenchmarkQuery 306 105 -65.69%
BenchmarkInsertBiasedSmallEpsilon 871 833 -4.36%
BenchmarkQuerySmallEpsilon 6782 6599 -2.70%
BenchmarkInsertTargeted 191 188 -1.57%
BenchmarkInsertTargetedSmallEpsilon 616 611 -0.81%
BenchmarkInsertBiased 177 176 -0.56%
Caleb Spare
9 years ago
| 192 | 192 | } |
| 193 | 193 | |
| 194 | 194 | func (s *stream) insert(v float64) { |
| 195 | fn := s.mergeFunc() | |
| 196 | fn(v, 1) | |
| 195 | s.merge(Samples{{v, 1, 0}}) | |
| 197 | 196 | } |
| 198 | 197 | |
| 199 | 198 | func (s *stream) merge(samples Samples) { |
| 200 | fn := s.mergeFunc() | |
| 201 | for _, s := range samples { | |
| 202 | fn(s.Value, s.Width) | |
| 203 | } | |
| 204 | } | |
| 205 | ||
| 206 | func (s *stream) mergeFunc() func(v, w float64) { | |
| 207 | // NOTE: I used a goto over defer because it bought me a few extra | |
| 208 | // nanoseconds. I know. I know. | |
| 209 | 199 | var r float64 |
| 210 | 200 | i := 0 |
| 211 | return func(v, w float64) { | |
| 201 | for _, sample := range samples { | |
| 212 | 202 | for ; i < len(s.l); i++ { |
| 213 | 203 | c := s.l[i] |
| 214 | if c.Value > v { | |
| 204 | if c.Value > sample.Value { | |
| 215 | 205 | // Insert at position i. |
| 216 | 206 | s.l = append(s.l, nil) |
| 217 | 207 | copy(s.l[i+1:], s.l[i:]) |
| 218 | s.l[i] = &Sample{v, w, math.Floor(s.ƒ(s, r)) - 1} | |
| 208 | s.l[i] = &Sample{sample.Value, sample.Width, math.Floor(s.ƒ(s, r)) - 1} | |
| 219 | 209 | i++ |
| 220 | 210 | goto inserted |
| 221 | 211 | } |
| 222 | 212 | r += c.Width |
| 223 | 213 | } |
| 224 | s.l = append(s.l, &Sample{v, w, 0}) | |
| 214 | s.l = append(s.l, &Sample{sample.Value, sample.Width, 0}) | |
| 225 | 215 | i++ |
| 226 | 216 | inserted: |
| 227 | s.n += w | |
| 217 | s.n += sample.Width | |
| 228 | 218 | } |
| 229 | 219 | } |
| 230 | 220 |