khenaidoo | 59ce9dd | 2019-11-11 13:05:32 -0500 | [diff] [blame^] | 1 | // Copyright 2014 The Prometheus Authors |
| 2 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 3 | // you may not use this file except in compliance with the License. |
| 4 | // You may obtain a copy of the License at |
| 5 | // |
| 6 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 7 | // |
| 8 | // Unless required by applicable law or agreed to in writing, software |
| 9 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 10 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 11 | // See the License for the specific language governing permissions and |
| 12 | // limitations under the License. |
| 13 | |
| 14 | package prometheus |
| 15 | |
| 16 | import ( |
| 17 | "fmt" |
| 18 | "math" |
| 19 | "runtime" |
| 20 | "sort" |
| 21 | "sync" |
| 22 | "sync/atomic" |
| 23 | "time" |
| 24 | |
| 25 | "github.com/beorn7/perks/quantile" |
| 26 | "github.com/golang/protobuf/proto" |
| 27 | |
| 28 | dto "github.com/prometheus/client_model/go" |
| 29 | ) |
| 30 | |
| 31 | // quantileLabel is used for the label that defines the quantile in a |
| 32 | // summary. |
| 33 | const quantileLabel = "quantile" |
| 34 | |
| 35 | // A Summary captures individual observations from an event or sample stream and |
| 36 | // summarizes them in a manner similar to traditional summary statistics: 1. sum |
| 37 | // of observations, 2. observation count, 3. rank estimations. |
| 38 | // |
| 39 | // A typical use-case is the observation of request latencies. By default, a |
| 40 | // Summary provides the median, the 90th and the 99th percentile of the latency |
| 41 | // as rank estimations. However, the default behavior will change in the |
| 42 | // upcoming v1.0.0 of the library. There will be no rank estimations at all by |
| 43 | // default. For a sane transition, it is recommended to set the desired rank |
| 44 | // estimations explicitly. |
| 45 | // |
| 46 | // Note that the rank estimations cannot be aggregated in a meaningful way with |
| 47 | // the Prometheus query language (i.e. you cannot average or add them). If you |
| 48 | // need aggregatable quantiles (e.g. you want the 99th percentile latency of all |
| 49 | // queries served across all instances of a service), consider the Histogram |
| 50 | // metric type. See the Prometheus documentation for more details. |
| 51 | // |
| 52 | // To create Summary instances, use NewSummary. |
| 53 | type Summary interface { |
| 54 | Metric |
| 55 | Collector |
| 56 | |
| 57 | // Observe adds a single observation to the summary. |
| 58 | Observe(float64) |
| 59 | } |
| 60 | |
| 61 | var errQuantileLabelNotAllowed = fmt.Errorf( |
| 62 | "%q is not allowed as label name in summaries", quantileLabel, |
| 63 | ) |
| 64 | |
| 65 | // Default values for SummaryOpts. |
| 66 | const ( |
| 67 | // DefMaxAge is the default duration for which observations stay |
| 68 | // relevant. |
| 69 | DefMaxAge time.Duration = 10 * time.Minute |
| 70 | // DefAgeBuckets is the default number of buckets used to calculate the |
| 71 | // age of observations. |
| 72 | DefAgeBuckets = 5 |
| 73 | // DefBufCap is the standard buffer size for collecting Summary observations. |
| 74 | DefBufCap = 500 |
| 75 | ) |
| 76 | |
| 77 | // SummaryOpts bundles the options for creating a Summary metric. It is |
| 78 | // mandatory to set Name to a non-empty string. While all other fields are |
| 79 | // optional and can safely be left at their zero value, it is recommended to set |
| 80 | // a help string and to explicitly set the Objectives field to the desired value |
| 81 | // as the default value will change in the upcoming v1.0.0 of the library. |
| 82 | type SummaryOpts struct { |
| 83 | // Namespace, Subsystem, and Name are components of the fully-qualified |
| 84 | // name of the Summary (created by joining these components with |
| 85 | // "_"). Only Name is mandatory, the others merely help structuring the |
| 86 | // name. Note that the fully-qualified name of the Summary must be a |
| 87 | // valid Prometheus metric name. |
| 88 | Namespace string |
| 89 | Subsystem string |
| 90 | Name string |
| 91 | |
| 92 | // Help provides information about this Summary. |
| 93 | // |
| 94 | // Metrics with the same fully-qualified name must have the same Help |
| 95 | // string. |
| 96 | Help string |
| 97 | |
| 98 | // ConstLabels are used to attach fixed labels to this metric. Metrics |
| 99 | // with the same fully-qualified name must have the same label names in |
| 100 | // their ConstLabels. |
| 101 | // |
| 102 | // Due to the way a Summary is represented in the Prometheus text format |
| 103 | // and how it is handled by the Prometheus server internally, “quantile” |
| 104 | // is an illegal label name. Construction of a Summary or SummaryVec |
| 105 | // will panic if this label name is used in ConstLabels. |
| 106 | // |
| 107 | // ConstLabels are only used rarely. In particular, do not use them to |
| 108 | // attach the same labels to all your metrics. Those use cases are |
| 109 | // better covered by target labels set by the scraping Prometheus |
| 110 | // server, or by one specific metric (e.g. a build_info or a |
| 111 | // machine_role metric). See also |
| 112 | // https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels,-not-static-scraped-labels |
| 113 | ConstLabels Labels |
| 114 | |
| 115 | // Objectives defines the quantile rank estimates with their respective |
| 116 | // absolute error. If Objectives[q] = e, then the value reported for q |
| 117 | // will be the φ-quantile value for some φ between q-e and q+e. The |
| 118 | // default value is an empty map, resulting in a summary without |
| 119 | // quantiles. |
| 120 | Objectives map[float64]float64 |
| 121 | |
| 122 | // MaxAge defines the duration for which an observation stays relevant |
| 123 | // for the summary. Must be positive. The default value is DefMaxAge. |
| 124 | MaxAge time.Duration |
| 125 | |
| 126 | // AgeBuckets is the number of buckets used to exclude observations that |
| 127 | // are older than MaxAge from the summary. A higher number has a |
| 128 | // resource penalty, so only increase it if the higher resolution is |
| 129 | // really required. For very high observation rates, you might want to |
| 130 | // reduce the number of age buckets. With only one age bucket, you will |
| 131 | // effectively see a complete reset of the summary each time MaxAge has |
| 132 | // passed. The default value is DefAgeBuckets. |
| 133 | AgeBuckets uint32 |
| 134 | |
| 135 | // BufCap defines the default sample stream buffer size. The default |
| 136 | // value of DefBufCap should suffice for most uses. If there is a need |
| 137 | // to increase the value, a multiple of 500 is recommended (because that |
| 138 | // is the internal buffer size of the underlying package |
| 139 | // "github.com/bmizerany/perks/quantile"). |
| 140 | BufCap uint32 |
| 141 | } |
| 142 | |
| 143 | // Problem with the sliding-window decay algorithm... The Merge method of |
| 144 | // perk/quantile is actually not working as advertised - and it might be |
| 145 | // unfixable, as the underlying algorithm is apparently not capable of merging |
| 146 | // summaries in the first place. To avoid using Merge, we are currently adding |
| 147 | // observations to _each_ age bucket, i.e. the effort to add a sample is |
| 148 | // essentially multiplied by the number of age buckets. When rotating age |
| 149 | // buckets, we empty the previous head stream. On scrape time, we simply take |
| 150 | // the quantiles from the head stream (no merging required). Result: More effort |
| 151 | // on observation time, less effort on scrape time, which is exactly the |
| 152 | // opposite of what we try to accomplish, but at least the results are correct. |
| 153 | // |
| 154 | // The quite elegant previous contraption to merge the age buckets efficiently |
| 155 | // on scrape time (see code up commit 6b9530d72ea715f0ba612c0120e6e09fbf1d49d0) |
| 156 | // can't be used anymore. |
| 157 | |
| 158 | // NewSummary creates a new Summary based on the provided SummaryOpts. |
| 159 | func NewSummary(opts SummaryOpts) Summary { |
| 160 | return newSummary( |
| 161 | NewDesc( |
| 162 | BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), |
| 163 | opts.Help, |
| 164 | nil, |
| 165 | opts.ConstLabels, |
| 166 | ), |
| 167 | opts, |
| 168 | ) |
| 169 | } |
| 170 | |
| 171 | func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary { |
| 172 | if len(desc.variableLabels) != len(labelValues) { |
| 173 | panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels, labelValues)) |
| 174 | } |
| 175 | |
| 176 | for _, n := range desc.variableLabels { |
| 177 | if n == quantileLabel { |
| 178 | panic(errQuantileLabelNotAllowed) |
| 179 | } |
| 180 | } |
| 181 | for _, lp := range desc.constLabelPairs { |
| 182 | if lp.GetName() == quantileLabel { |
| 183 | panic(errQuantileLabelNotAllowed) |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | if opts.Objectives == nil { |
| 188 | opts.Objectives = map[float64]float64{} |
| 189 | } |
| 190 | |
| 191 | if opts.MaxAge < 0 { |
| 192 | panic(fmt.Errorf("illegal max age MaxAge=%v", opts.MaxAge)) |
| 193 | } |
| 194 | if opts.MaxAge == 0 { |
| 195 | opts.MaxAge = DefMaxAge |
| 196 | } |
| 197 | |
| 198 | if opts.AgeBuckets == 0 { |
| 199 | opts.AgeBuckets = DefAgeBuckets |
| 200 | } |
| 201 | |
| 202 | if opts.BufCap == 0 { |
| 203 | opts.BufCap = DefBufCap |
| 204 | } |
| 205 | |
| 206 | if len(opts.Objectives) == 0 { |
| 207 | // Use the lock-free implementation of a Summary without objectives. |
| 208 | s := &noObjectivesSummary{ |
| 209 | desc: desc, |
| 210 | labelPairs: makeLabelPairs(desc, labelValues), |
| 211 | counts: [2]*summaryCounts{&summaryCounts{}, &summaryCounts{}}, |
| 212 | } |
| 213 | s.init(s) // Init self-collection. |
| 214 | return s |
| 215 | } |
| 216 | |
| 217 | s := &summary{ |
| 218 | desc: desc, |
| 219 | |
| 220 | objectives: opts.Objectives, |
| 221 | sortedObjectives: make([]float64, 0, len(opts.Objectives)), |
| 222 | |
| 223 | labelPairs: makeLabelPairs(desc, labelValues), |
| 224 | |
| 225 | hotBuf: make([]float64, 0, opts.BufCap), |
| 226 | coldBuf: make([]float64, 0, opts.BufCap), |
| 227 | streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets), |
| 228 | } |
| 229 | s.headStreamExpTime = time.Now().Add(s.streamDuration) |
| 230 | s.hotBufExpTime = s.headStreamExpTime |
| 231 | |
| 232 | for i := uint32(0); i < opts.AgeBuckets; i++ { |
| 233 | s.streams = append(s.streams, s.newStream()) |
| 234 | } |
| 235 | s.headStream = s.streams[0] |
| 236 | |
| 237 | for qu := range s.objectives { |
| 238 | s.sortedObjectives = append(s.sortedObjectives, qu) |
| 239 | } |
| 240 | sort.Float64s(s.sortedObjectives) |
| 241 | |
| 242 | s.init(s) // Init self-collection. |
| 243 | return s |
| 244 | } |
| 245 | |
| 246 | type summary struct { |
| 247 | selfCollector |
| 248 | |
| 249 | bufMtx sync.Mutex // Protects hotBuf and hotBufExpTime. |
| 250 | mtx sync.Mutex // Protects every other moving part. |
| 251 | // Lock bufMtx before mtx if both are needed. |
| 252 | |
| 253 | desc *Desc |
| 254 | |
| 255 | objectives map[float64]float64 |
| 256 | sortedObjectives []float64 |
| 257 | |
| 258 | labelPairs []*dto.LabelPair |
| 259 | |
| 260 | sum float64 |
| 261 | cnt uint64 |
| 262 | |
| 263 | hotBuf, coldBuf []float64 |
| 264 | |
| 265 | streams []*quantile.Stream |
| 266 | streamDuration time.Duration |
| 267 | headStream *quantile.Stream |
| 268 | headStreamIdx int |
| 269 | headStreamExpTime, hotBufExpTime time.Time |
| 270 | } |
| 271 | |
| 272 | func (s *summary) Desc() *Desc { |
| 273 | return s.desc |
| 274 | } |
| 275 | |
| 276 | func (s *summary) Observe(v float64) { |
| 277 | s.bufMtx.Lock() |
| 278 | defer s.bufMtx.Unlock() |
| 279 | |
| 280 | now := time.Now() |
| 281 | if now.After(s.hotBufExpTime) { |
| 282 | s.asyncFlush(now) |
| 283 | } |
| 284 | s.hotBuf = append(s.hotBuf, v) |
| 285 | if len(s.hotBuf) == cap(s.hotBuf) { |
| 286 | s.asyncFlush(now) |
| 287 | } |
| 288 | } |
| 289 | |
| 290 | func (s *summary) Write(out *dto.Metric) error { |
| 291 | sum := &dto.Summary{} |
| 292 | qs := make([]*dto.Quantile, 0, len(s.objectives)) |
| 293 | |
| 294 | s.bufMtx.Lock() |
| 295 | s.mtx.Lock() |
| 296 | // Swap bufs even if hotBuf is empty to set new hotBufExpTime. |
| 297 | s.swapBufs(time.Now()) |
| 298 | s.bufMtx.Unlock() |
| 299 | |
| 300 | s.flushColdBuf() |
| 301 | sum.SampleCount = proto.Uint64(s.cnt) |
| 302 | sum.SampleSum = proto.Float64(s.sum) |
| 303 | |
| 304 | for _, rank := range s.sortedObjectives { |
| 305 | var q float64 |
| 306 | if s.headStream.Count() == 0 { |
| 307 | q = math.NaN() |
| 308 | } else { |
| 309 | q = s.headStream.Query(rank) |
| 310 | } |
| 311 | qs = append(qs, &dto.Quantile{ |
| 312 | Quantile: proto.Float64(rank), |
| 313 | Value: proto.Float64(q), |
| 314 | }) |
| 315 | } |
| 316 | |
| 317 | s.mtx.Unlock() |
| 318 | |
| 319 | if len(qs) > 0 { |
| 320 | sort.Sort(quantSort(qs)) |
| 321 | } |
| 322 | sum.Quantile = qs |
| 323 | |
| 324 | out.Summary = sum |
| 325 | out.Label = s.labelPairs |
| 326 | return nil |
| 327 | } |
| 328 | |
| 329 | func (s *summary) newStream() *quantile.Stream { |
| 330 | return quantile.NewTargeted(s.objectives) |
| 331 | } |
| 332 | |
| 333 | // asyncFlush needs bufMtx locked. |
| 334 | func (s *summary) asyncFlush(now time.Time) { |
| 335 | s.mtx.Lock() |
| 336 | s.swapBufs(now) |
| 337 | |
| 338 | // Unblock the original goroutine that was responsible for the mutation |
| 339 | // that triggered the compaction. But hold onto the global non-buffer |
| 340 | // state mutex until the operation finishes. |
| 341 | go func() { |
| 342 | s.flushColdBuf() |
| 343 | s.mtx.Unlock() |
| 344 | }() |
| 345 | } |
| 346 | |
| 347 | // rotateStreams needs mtx AND bufMtx locked. |
| 348 | func (s *summary) maybeRotateStreams() { |
| 349 | for !s.hotBufExpTime.Equal(s.headStreamExpTime) { |
| 350 | s.headStream.Reset() |
| 351 | s.headStreamIdx++ |
| 352 | if s.headStreamIdx >= len(s.streams) { |
| 353 | s.headStreamIdx = 0 |
| 354 | } |
| 355 | s.headStream = s.streams[s.headStreamIdx] |
| 356 | s.headStreamExpTime = s.headStreamExpTime.Add(s.streamDuration) |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | // flushColdBuf needs mtx locked. |
| 361 | func (s *summary) flushColdBuf() { |
| 362 | for _, v := range s.coldBuf { |
| 363 | for _, stream := range s.streams { |
| 364 | stream.Insert(v) |
| 365 | } |
| 366 | s.cnt++ |
| 367 | s.sum += v |
| 368 | } |
| 369 | s.coldBuf = s.coldBuf[0:0] |
| 370 | s.maybeRotateStreams() |
| 371 | } |
| 372 | |
| 373 | // swapBufs needs mtx AND bufMtx locked, coldBuf must be empty. |
| 374 | func (s *summary) swapBufs(now time.Time) { |
| 375 | if len(s.coldBuf) != 0 { |
| 376 | panic("coldBuf is not empty") |
| 377 | } |
| 378 | s.hotBuf, s.coldBuf = s.coldBuf, s.hotBuf |
| 379 | // hotBuf is now empty and gets new expiration set. |
| 380 | for now.After(s.hotBufExpTime) { |
| 381 | s.hotBufExpTime = s.hotBufExpTime.Add(s.streamDuration) |
| 382 | } |
| 383 | } |
| 384 | |
| 385 | type summaryCounts struct { |
| 386 | // sumBits contains the bits of the float64 representing the sum of all |
| 387 | // observations. sumBits and count have to go first in the struct to |
| 388 | // guarantee alignment for atomic operations. |
| 389 | // http://golang.org/pkg/sync/atomic/#pkg-note-BUG |
| 390 | sumBits uint64 |
| 391 | count uint64 |
| 392 | } |
| 393 | |
| 394 | type noObjectivesSummary struct { |
| 395 | // countAndHotIdx enables lock-free writes with use of atomic updates. |
| 396 | // The most significant bit is the hot index [0 or 1] of the count field |
| 397 | // below. Observe calls update the hot one. All remaining bits count the |
| 398 | // number of Observe calls. Observe starts by incrementing this counter, |
| 399 | // and finish by incrementing the count field in the respective |
| 400 | // summaryCounts, as a marker for completion. |
| 401 | // |
| 402 | // Calls of the Write method (which are non-mutating reads from the |
| 403 | // perspective of the summary) swap the hot–cold under the writeMtx |
| 404 | // lock. A cooldown is awaited (while locked) by comparing the number of |
| 405 | // observations with the initiation count. Once they match, then the |
| 406 | // last observation on the now cool one has completed. All cool fields must |
| 407 | // be merged into the new hot before releasing writeMtx. |
| 408 | |
| 409 | // Fields with atomic access first! See alignment constraint: |
| 410 | // http://golang.org/pkg/sync/atomic/#pkg-note-BUG |
| 411 | countAndHotIdx uint64 |
| 412 | |
| 413 | selfCollector |
| 414 | desc *Desc |
| 415 | writeMtx sync.Mutex // Only used in the Write method. |
| 416 | |
| 417 | // Two counts, one is "hot" for lock-free observations, the other is |
| 418 | // "cold" for writing out a dto.Metric. It has to be an array of |
| 419 | // pointers to guarantee 64bit alignment of the histogramCounts, see |
| 420 | // http://golang.org/pkg/sync/atomic/#pkg-note-BUG. |
| 421 | counts [2]*summaryCounts |
| 422 | |
| 423 | labelPairs []*dto.LabelPair |
| 424 | } |
| 425 | |
| 426 | func (s *noObjectivesSummary) Desc() *Desc { |
| 427 | return s.desc |
| 428 | } |
| 429 | |
| 430 | func (s *noObjectivesSummary) Observe(v float64) { |
| 431 | // We increment h.countAndHotIdx so that the counter in the lower |
| 432 | // 63 bits gets incremented. At the same time, we get the new value |
| 433 | // back, which we can use to find the currently-hot counts. |
| 434 | n := atomic.AddUint64(&s.countAndHotIdx, 1) |
| 435 | hotCounts := s.counts[n>>63] |
| 436 | |
| 437 | for { |
| 438 | oldBits := atomic.LoadUint64(&hotCounts.sumBits) |
| 439 | newBits := math.Float64bits(math.Float64frombits(oldBits) + v) |
| 440 | if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) { |
| 441 | break |
| 442 | } |
| 443 | } |
| 444 | // Increment count last as we take it as a signal that the observation |
| 445 | // is complete. |
| 446 | atomic.AddUint64(&hotCounts.count, 1) |
| 447 | } |
| 448 | |
| 449 | func (s *noObjectivesSummary) Write(out *dto.Metric) error { |
| 450 | // For simplicity, we protect this whole method by a mutex. It is not in |
| 451 | // the hot path, i.e. Observe is called much more often than Write. The |
| 452 | // complication of making Write lock-free isn't worth it, if possible at |
| 453 | // all. |
| 454 | s.writeMtx.Lock() |
| 455 | defer s.writeMtx.Unlock() |
| 456 | |
| 457 | // Adding 1<<63 switches the hot index (from 0 to 1 or from 1 to 0) |
| 458 | // without touching the count bits. See the struct comments for a full |
| 459 | // description of the algorithm. |
| 460 | n := atomic.AddUint64(&s.countAndHotIdx, 1<<63) |
| 461 | // count is contained unchanged in the lower 63 bits. |
| 462 | count := n & ((1 << 63) - 1) |
| 463 | // The most significant bit tells us which counts is hot. The complement |
| 464 | // is thus the cold one. |
| 465 | hotCounts := s.counts[n>>63] |
| 466 | coldCounts := s.counts[(^n)>>63] |
| 467 | |
| 468 | // Await cooldown. |
| 469 | for count != atomic.LoadUint64(&coldCounts.count) { |
| 470 | runtime.Gosched() // Let observations get work done. |
| 471 | } |
| 472 | |
| 473 | sum := &dto.Summary{ |
| 474 | SampleCount: proto.Uint64(count), |
| 475 | SampleSum: proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))), |
| 476 | } |
| 477 | |
| 478 | out.Summary = sum |
| 479 | out.Label = s.labelPairs |
| 480 | |
| 481 | // Finally add all the cold counts to the new hot counts and reset the cold counts. |
| 482 | atomic.AddUint64(&hotCounts.count, count) |
| 483 | atomic.StoreUint64(&coldCounts.count, 0) |
| 484 | for { |
| 485 | oldBits := atomic.LoadUint64(&hotCounts.sumBits) |
| 486 | newBits := math.Float64bits(math.Float64frombits(oldBits) + sum.GetSampleSum()) |
| 487 | if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) { |
| 488 | atomic.StoreUint64(&coldCounts.sumBits, 0) |
| 489 | break |
| 490 | } |
| 491 | } |
| 492 | return nil |
| 493 | } |
| 494 | |
| 495 | type quantSort []*dto.Quantile |
| 496 | |
| 497 | func (s quantSort) Len() int { |
| 498 | return len(s) |
| 499 | } |
| 500 | |
| 501 | func (s quantSort) Swap(i, j int) { |
| 502 | s[i], s[j] = s[j], s[i] |
| 503 | } |
| 504 | |
| 505 | func (s quantSort) Less(i, j int) bool { |
| 506 | return s[i].GetQuantile() < s[j].GetQuantile() |
| 507 | } |
| 508 | |
| 509 | // SummaryVec is a Collector that bundles a set of Summaries that all share the |
| 510 | // same Desc, but have different values for their variable labels. This is used |
| 511 | // if you want to count the same thing partitioned by various dimensions |
| 512 | // (e.g. HTTP request latencies, partitioned by status code and method). Create |
| 513 | // instances with NewSummaryVec. |
| 514 | type SummaryVec struct { |
| 515 | *metricVec |
| 516 | } |
| 517 | |
| 518 | // NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and |
| 519 | // partitioned by the given label names. |
| 520 | // |
| 521 | // Due to the way a Summary is represented in the Prometheus text format and how |
| 522 | // it is handled by the Prometheus server internally, “quantile” is an illegal |
| 523 | // label name. NewSummaryVec will panic if this label name is used. |
| 524 | func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec { |
| 525 | for _, ln := range labelNames { |
| 526 | if ln == quantileLabel { |
| 527 | panic(errQuantileLabelNotAllowed) |
| 528 | } |
| 529 | } |
| 530 | desc := NewDesc( |
| 531 | BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), |
| 532 | opts.Help, |
| 533 | labelNames, |
| 534 | opts.ConstLabels, |
| 535 | ) |
| 536 | return &SummaryVec{ |
| 537 | metricVec: newMetricVec(desc, func(lvs ...string) Metric { |
| 538 | return newSummary(desc, opts, lvs...) |
| 539 | }), |
| 540 | } |
| 541 | } |
| 542 | |
| 543 | // GetMetricWithLabelValues returns the Summary for the given slice of label |
| 544 | // values (same order as the VariableLabels in Desc). If that combination of |
| 545 | // label values is accessed for the first time, a new Summary is created. |
| 546 | // |
| 547 | // It is possible to call this method without using the returned Summary to only |
| 548 | // create the new Summary but leave it at its starting value, a Summary without |
| 549 | // any observations. |
| 550 | // |
| 551 | // Keeping the Summary for later use is possible (and should be considered if |
| 552 | // performance is critical), but keep in mind that Reset, DeleteLabelValues and |
| 553 | // Delete can be used to delete the Summary from the SummaryVec. In that case, |
| 554 | // the Summary will still exist, but it will not be exported anymore, even if a |
| 555 | // Summary with the same label values is created later. See also the CounterVec |
| 556 | // example. |
| 557 | // |
| 558 | // An error is returned if the number of label values is not the same as the |
| 559 | // number of VariableLabels in Desc (minus any curried labels). |
| 560 | // |
| 561 | // Note that for more than one label value, this method is prone to mistakes |
| 562 | // caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as |
| 563 | // an alternative to avoid that type of mistake. For higher label numbers, the |
| 564 | // latter has a much more readable (albeit more verbose) syntax, but it comes |
| 565 | // with a performance overhead (for creating and processing the Labels map). |
| 566 | // See also the GaugeVec example. |
| 567 | func (v *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) { |
| 568 | metric, err := v.metricVec.getMetricWithLabelValues(lvs...) |
| 569 | if metric != nil { |
| 570 | return metric.(Observer), err |
| 571 | } |
| 572 | return nil, err |
| 573 | } |
| 574 | |
| 575 | // GetMetricWith returns the Summary for the given Labels map (the label names |
| 576 | // must match those of the VariableLabels in Desc). If that label map is |
| 577 | // accessed for the first time, a new Summary is created. Implications of |
| 578 | // creating a Summary without using it and keeping the Summary for later use are |
| 579 | // the same as for GetMetricWithLabelValues. |
| 580 | // |
| 581 | // An error is returned if the number and names of the Labels are inconsistent |
| 582 | // with those of the VariableLabels in Desc (minus any curried labels). |
| 583 | // |
| 584 | // This method is used for the same purpose as |
| 585 | // GetMetricWithLabelValues(...string). See there for pros and cons of the two |
| 586 | // methods. |
| 587 | func (v *SummaryVec) GetMetricWith(labels Labels) (Observer, error) { |
| 588 | metric, err := v.metricVec.getMetricWith(labels) |
| 589 | if metric != nil { |
| 590 | return metric.(Observer), err |
| 591 | } |
| 592 | return nil, err |
| 593 | } |
| 594 | |
| 595 | // WithLabelValues works as GetMetricWithLabelValues, but panics where |
| 596 | // GetMetricWithLabelValues would have returned an error. Not returning an |
| 597 | // error allows shortcuts like |
| 598 | // myVec.WithLabelValues("404", "GET").Observe(42.21) |
| 599 | func (v *SummaryVec) WithLabelValues(lvs ...string) Observer { |
| 600 | s, err := v.GetMetricWithLabelValues(lvs...) |
| 601 | if err != nil { |
| 602 | panic(err) |
| 603 | } |
| 604 | return s |
| 605 | } |
| 606 | |
| 607 | // With works as GetMetricWith, but panics where GetMetricWithLabels would have |
| 608 | // returned an error. Not returning an error allows shortcuts like |
| 609 | // myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Observe(42.21) |
| 610 | func (v *SummaryVec) With(labels Labels) Observer { |
| 611 | s, err := v.GetMetricWith(labels) |
| 612 | if err != nil { |
| 613 | panic(err) |
| 614 | } |
| 615 | return s |
| 616 | } |
| 617 | |
| 618 | // CurryWith returns a vector curried with the provided labels, i.e. the |
| 619 | // returned vector has those labels pre-set for all labeled operations performed |
| 620 | // on it. The cardinality of the curried vector is reduced accordingly. The |
| 621 | // order of the remaining labels stays the same (just with the curried labels |
| 622 | // taken out of the sequence – which is relevant for the |
| 623 | // (GetMetric)WithLabelValues methods). It is possible to curry a curried |
| 624 | // vector, but only with labels not yet used for currying before. |
| 625 | // |
| 626 | // The metrics contained in the SummaryVec are shared between the curried and |
| 627 | // uncurried vectors. They are just accessed differently. Curried and uncurried |
| 628 | // vectors behave identically in terms of collection. Only one must be |
| 629 | // registered with a given registry (usually the uncurried version). The Reset |
| 630 | // method deletes all metrics, even if called on a curried vector. |
| 631 | func (v *SummaryVec) CurryWith(labels Labels) (ObserverVec, error) { |
| 632 | vec, err := v.curryWith(labels) |
| 633 | if vec != nil { |
| 634 | return &SummaryVec{vec}, err |
| 635 | } |
| 636 | return nil, err |
| 637 | } |
| 638 | |
| 639 | // MustCurryWith works as CurryWith but panics where CurryWith would have |
| 640 | // returned an error. |
| 641 | func (v *SummaryVec) MustCurryWith(labels Labels) ObserverVec { |
| 642 | vec, err := v.CurryWith(labels) |
| 643 | if err != nil { |
| 644 | panic(err) |
| 645 | } |
| 646 | return vec |
| 647 | } |
| 648 | |
| 649 | type constSummary struct { |
| 650 | desc *Desc |
| 651 | count uint64 |
| 652 | sum float64 |
| 653 | quantiles map[float64]float64 |
| 654 | labelPairs []*dto.LabelPair |
| 655 | } |
| 656 | |
| 657 | func (s *constSummary) Desc() *Desc { |
| 658 | return s.desc |
| 659 | } |
| 660 | |
| 661 | func (s *constSummary) Write(out *dto.Metric) error { |
| 662 | sum := &dto.Summary{} |
| 663 | qs := make([]*dto.Quantile, 0, len(s.quantiles)) |
| 664 | |
| 665 | sum.SampleCount = proto.Uint64(s.count) |
| 666 | sum.SampleSum = proto.Float64(s.sum) |
| 667 | |
| 668 | for rank, q := range s.quantiles { |
| 669 | qs = append(qs, &dto.Quantile{ |
| 670 | Quantile: proto.Float64(rank), |
| 671 | Value: proto.Float64(q), |
| 672 | }) |
| 673 | } |
| 674 | |
| 675 | if len(qs) > 0 { |
| 676 | sort.Sort(quantSort(qs)) |
| 677 | } |
| 678 | sum.Quantile = qs |
| 679 | |
| 680 | out.Summary = sum |
| 681 | out.Label = s.labelPairs |
| 682 | |
| 683 | return nil |
| 684 | } |
| 685 | |
| 686 | // NewConstSummary returns a metric representing a Prometheus summary with fixed |
| 687 | // values for the count, sum, and quantiles. As those parameters cannot be |
| 688 | // changed, the returned value does not implement the Summary interface (but |
| 689 | // only the Metric interface). Users of this package will not have much use for |
| 690 | // it in regular operations. However, when implementing custom Collectors, it is |
| 691 | // useful as a throw-away metric that is generated on the fly to send it to |
| 692 | // Prometheus in the Collect method. |
| 693 | // |
| 694 | // quantiles maps ranks to quantile values. For example, a median latency of |
| 695 | // 0.23s and a 99th percentile latency of 0.56s would be expressed as: |
| 696 | // map[float64]float64{0.5: 0.23, 0.99: 0.56} |
| 697 | // |
| 698 | // NewConstSummary returns an error if the length of labelValues is not |
| 699 | // consistent with the variable labels in Desc or if Desc is invalid. |
| 700 | func NewConstSummary( |
| 701 | desc *Desc, |
| 702 | count uint64, |
| 703 | sum float64, |
| 704 | quantiles map[float64]float64, |
| 705 | labelValues ...string, |
| 706 | ) (Metric, error) { |
| 707 | if desc.err != nil { |
| 708 | return nil, desc.err |
| 709 | } |
| 710 | if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil { |
| 711 | return nil, err |
| 712 | } |
| 713 | return &constSummary{ |
| 714 | desc: desc, |
| 715 | count: count, |
| 716 | sum: sum, |
| 717 | quantiles: quantiles, |
| 718 | labelPairs: makeLabelPairs(desc, labelValues), |
| 719 | }, nil |
| 720 | } |
| 721 | |
| 722 | // MustNewConstSummary is a version of NewConstSummary that panics where |
| 723 | // NewConstMetric would have returned an error. |
| 724 | func MustNewConstSummary( |
| 725 | desc *Desc, |
| 726 | count uint64, |
| 727 | sum float64, |
| 728 | quantiles map[float64]float64, |
| 729 | labelValues ...string, |
| 730 | ) Metric { |
| 731 | m, err := NewConstSummary(desc, count, sum, quantiles, labelValues...) |
| 732 | if err != nil { |
| 733 | panic(err) |
| 734 | } |
| 735 | return m |
| 736 | } |