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Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/histogram.go')
| -rw-r--r-- | vendor/github.com/prometheus/client_golang/prometheus/histogram.go | 670 |
1 files changed, 0 insertions, 670 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go deleted file mode 100644 index 893802fd6..000000000 --- a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go +++ /dev/null @@ -1,670 +0,0 @@ -// Copyright 2015 The Prometheus Authors -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -package prometheus - -import ( - "fmt" - "math" - "runtime" - "sort" - "sync" - "sync/atomic" - "time" - - //nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility. - "github.com/golang/protobuf/proto" - - dto "github.com/prometheus/client_model/go" -) - -// A Histogram counts individual observations from an event or sample stream in -// configurable buckets. Similar to a summary, it also provides a sum of -// observations and an observation count. -// -// On the Prometheus server, quantiles can be calculated from a Histogram using -// the histogram_quantile function in the query language. -// -// Note that Histograms, in contrast to Summaries, can be aggregated with the -// Prometheus query language (see the documentation for detailed -// procedures). However, Histograms require the user to pre-define suitable -// buckets, and they are in general less accurate. The Observe method of a -// Histogram has a very low performance overhead in comparison with the Observe -// method of a Summary. -// -// To create Histogram instances, use NewHistogram. -type Histogram interface { - Metric - Collector - - // Observe adds a single observation to the histogram. Observations are - // usually positive or zero. Negative observations are accepted but - // prevent current versions of Prometheus from properly detecting - // counter resets in the sum of observations. See - // https://prometheus.io/docs/practices/histograms/#count-and-sum-of-observations - // for details. - Observe(float64) -} - -// bucketLabel is used for the label that defines the upper bound of a -// bucket of a histogram ("le" -> "less or equal"). -const bucketLabel = "le" - -// DefBuckets are the default Histogram buckets. The default buckets are -// tailored to broadly measure the response time (in seconds) of a network -// service. Most likely, however, you will be required to define buckets -// customized to your use case. -var ( - DefBuckets = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10} - - errBucketLabelNotAllowed = fmt.Errorf( - "%q is not allowed as label name in histograms", bucketLabel, - ) -) - -// LinearBuckets creates 'count' buckets, each 'width' wide, where the lowest -// bucket has an upper bound of 'start'. The final +Inf bucket is not counted -// and not included in the returned slice. The returned slice is meant to be -// used for the Buckets field of HistogramOpts. -// -// The function panics if 'count' is zero or negative. -func LinearBuckets(start, width float64, count int) []float64 { - if count < 1 { - panic("LinearBuckets needs a positive count") - } - buckets := make([]float64, count) - for i := range buckets { - buckets[i] = start - start += width - } - return buckets -} - -// ExponentialBuckets creates 'count' buckets, where the lowest bucket has an -// upper bound of 'start' and each following bucket's upper bound is 'factor' -// times the previous bucket's upper bound. The final +Inf bucket is not counted -// and not included in the returned slice. The returned slice is meant to be -// used for the Buckets field of HistogramOpts. -// -// The function panics if 'count' is 0 or negative, if 'start' is 0 or negative, -// or if 'factor' is less than or equal 1. -func ExponentialBuckets(start, factor float64, count int) []float64 { - if count < 1 { - panic("ExponentialBuckets needs a positive count") - } - if start <= 0 { - panic("ExponentialBuckets needs a positive start value") - } - if factor <= 1 { - panic("ExponentialBuckets needs a factor greater than 1") - } - buckets := make([]float64, count) - for i := range buckets { - buckets[i] = start - start *= factor - } - return buckets -} - -// ExponentialBucketsRange creates 'count' buckets, where the lowest bucket is -// 'min' and the highest bucket is 'max'. The final +Inf bucket is not counted -// and not included in the returned slice. The returned slice is meant to be -// used for the Buckets field of HistogramOpts. -// -// The function panics if 'count' is 0 or negative, if 'min' is 0 or negative. -func ExponentialBucketsRange(min, max float64, count int) []float64 { - if count < 1 { - panic("ExponentialBucketsRange count needs a positive count") - } - if min <= 0 { - panic("ExponentialBucketsRange min needs to be greater than 0") - } - - // Formula for exponential buckets. - // max = min*growthFactor^(bucketCount-1) - - // We know max/min and highest bucket. Solve for growthFactor. - growthFactor := math.Pow(max/min, 1.0/float64(count-1)) - - // Now that we know growthFactor, solve for each bucket. - buckets := make([]float64, count) - for i := 1; i <= count; i++ { - buckets[i-1] = min * math.Pow(growthFactor, float64(i-1)) - } - return buckets -} - -// HistogramOpts bundles the options for creating a Histogram metric. It is -// mandatory to set Name to a non-empty string. All other fields are optional -// and can safely be left at their zero value, although it is strongly -// encouraged to set a Help string. -type HistogramOpts struct { - // Namespace, Subsystem, and Name are components of the fully-qualified - // name of the Histogram (created by joining these components with - // "_"). Only Name is mandatory, the others merely help structuring the - // name. Note that the fully-qualified name of the Histogram must be a - // valid Prometheus metric name. - Namespace string - Subsystem string - Name string - - // Help provides information about this Histogram. - // - // Metrics with the same fully-qualified name must have the same Help - // string. - Help string - - // ConstLabels are used to attach fixed labels to this metric. Metrics - // with the same fully-qualified name must have the same label names in - // their ConstLabels. - // - // ConstLabels are only used rarely. In particular, do not use them to - // attach the same labels to all your metrics. Those use cases are - // better covered by target labels set by the scraping Prometheus - // server, or by one specific metric (e.g. a build_info or a - // machine_role metric). See also - // https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels-not-static-scraped-labels - ConstLabels Labels - - // Buckets defines the buckets into which observations are counted. Each - // element in the slice is the upper inclusive bound of a bucket. The - // values must be sorted in strictly increasing order. There is no need - // to add a highest bucket with +Inf bound, it will be added - // implicitly. The default value is DefBuckets. - Buckets []float64 -} - -// NewHistogram creates a new Histogram based on the provided HistogramOpts. It -// panics if the buckets in HistogramOpts are not in strictly increasing order. -// -// The returned implementation also implements ExemplarObserver. It is safe to -// perform the corresponding type assertion. Exemplars are tracked separately -// for each bucket. -func NewHistogram(opts HistogramOpts) Histogram { - return newHistogram( - NewDesc( - BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), - opts.Help, - nil, - opts.ConstLabels, - ), - opts, - ) -} - -func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogram { - if len(desc.variableLabels) != len(labelValues) { - panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels, labelValues)) - } - - for _, n := range desc.variableLabels { - if n == bucketLabel { - panic(errBucketLabelNotAllowed) - } - } - for _, lp := range desc.constLabelPairs { - if lp.GetName() == bucketLabel { - panic(errBucketLabelNotAllowed) - } - } - - if len(opts.Buckets) == 0 { - opts.Buckets = DefBuckets - } - - h := &histogram{ - desc: desc, - upperBounds: opts.Buckets, - labelPairs: MakeLabelPairs(desc, labelValues), - counts: [2]*histogramCounts{{}, {}}, - now: time.Now, - } - for i, upperBound := range h.upperBounds { - if i < len(h.upperBounds)-1 { - if upperBound >= h.upperBounds[i+1] { - panic(fmt.Errorf( - "histogram buckets must be in increasing order: %f >= %f", - upperBound, h.upperBounds[i+1], - )) - } - } else { - if math.IsInf(upperBound, +1) { - // The +Inf bucket is implicit. Remove it here. - h.upperBounds = h.upperBounds[:i] - } - } - } - // Finally we know the final length of h.upperBounds and can make buckets - // for both counts as well as exemplars: - h.counts[0].buckets = make([]uint64, len(h.upperBounds)) - h.counts[1].buckets = make([]uint64, len(h.upperBounds)) - h.exemplars = make([]atomic.Value, len(h.upperBounds)+1) - - h.init(h) // Init self-collection. - return h -} - -type histogramCounts struct { - // sumBits contains the bits of the float64 representing the sum of all - // observations. sumBits and count have to go first in the struct to - // guarantee alignment for atomic operations. - // http://golang.org/pkg/sync/atomic/#pkg-note-BUG - sumBits uint64 - count uint64 - buckets []uint64 -} - -type histogram struct { - // countAndHotIdx enables lock-free writes with use of atomic updates. - // The most significant bit is the hot index [0 or 1] of the count field - // below. Observe calls update the hot one. All remaining bits count the - // number of Observe calls. Observe starts by incrementing this counter, - // and finish by incrementing the count field in the respective - // histogramCounts, as a marker for completion. - // - // Calls of the Write method (which are non-mutating reads from the - // perspective of the histogram) swap the hot–cold under the writeMtx - // lock. A cooldown is awaited (while locked) by comparing the number of - // observations with the initiation count. Once they match, then the - // last observation on the now cool one has completed. All cool fields must - // be merged into the new hot before releasing writeMtx. - // - // Fields with atomic access first! See alignment constraint: - // http://golang.org/pkg/sync/atomic/#pkg-note-BUG - countAndHotIdx uint64 - - selfCollector - desc *Desc - writeMtx sync.Mutex // Only used in the Write method. - - // Two counts, one is "hot" for lock-free observations, the other is - // "cold" for writing out a dto.Metric. It has to be an array of - // pointers to guarantee 64bit alignment of the histogramCounts, see - // http://golang.org/pkg/sync/atomic/#pkg-note-BUG. - counts [2]*histogramCounts - - upperBounds []float64 - labelPairs []*dto.LabelPair - exemplars []atomic.Value // One more than buckets (to include +Inf), each a *dto.Exemplar. - - now func() time.Time // To mock out time.Now() for testing. -} - -func (h *histogram) Desc() *Desc { - return h.desc -} - -func (h *histogram) Observe(v float64) { - h.observe(v, h.findBucket(v)) -} - -func (h *histogram) ObserveWithExemplar(v float64, e Labels) { - i := h.findBucket(v) - h.observe(v, i) - h.updateExemplar(v, i, e) -} - -func (h *histogram) Write(out *dto.Metric) error { - // For simplicity, we protect this whole method by a mutex. It is not in - // the hot path, i.e. Observe is called much more often than Write. The - // complication of making Write lock-free isn't worth it, if possible at - // all. - h.writeMtx.Lock() - defer h.writeMtx.Unlock() - - // Adding 1<<63 switches the hot index (from 0 to 1 or from 1 to 0) - // without touching the count bits. See the struct comments for a full - // description of the algorithm. - n := atomic.AddUint64(&h.countAndHotIdx, 1<<63) - // count is contained unchanged in the lower 63 bits. - count := n & ((1 << 63) - 1) - // The most significant bit tells us which counts is hot. The complement - // is thus the cold one. - hotCounts := h.counts[n>>63] - coldCounts := h.counts[(^n)>>63] - - // Await cooldown. - for count != atomic.LoadUint64(&coldCounts.count) { - runtime.Gosched() // Let observations get work done. - } - - his := &dto.Histogram{ - Bucket: make([]*dto.Bucket, len(h.upperBounds)), - SampleCount: proto.Uint64(count), - SampleSum: proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))), - } - var cumCount uint64 - for i, upperBound := range h.upperBounds { - cumCount += atomic.LoadUint64(&coldCounts.buckets[i]) - his.Bucket[i] = &dto.Bucket{ - CumulativeCount: proto.Uint64(cumCount), - UpperBound: proto.Float64(upperBound), - } - if e := h.exemplars[i].Load(); e != nil { - his.Bucket[i].Exemplar = e.(*dto.Exemplar) - } - } - // If there is an exemplar for the +Inf bucket, we have to add that bucket explicitly. - if e := h.exemplars[len(h.upperBounds)].Load(); e != nil { - b := &dto.Bucket{ - CumulativeCount: proto.Uint64(count), - UpperBound: proto.Float64(math.Inf(1)), - Exemplar: e.(*dto.Exemplar), - } - his.Bucket = append(his.Bucket, b) - } - - out.Histogram = his - out.Label = h.labelPairs - - // Finally add all the cold counts to the new hot counts and reset the cold counts. - atomic.AddUint64(&hotCounts.count, count) - atomic.StoreUint64(&coldCounts.count, 0) - for { - oldBits := atomic.LoadUint64(&hotCounts.sumBits) - newBits := math.Float64bits(math.Float64frombits(oldBits) + his.GetSampleSum()) - if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) { - atomic.StoreUint64(&coldCounts.sumBits, 0) - break - } - } - for i := range h.upperBounds { - atomic.AddUint64(&hotCounts.buckets[i], atomic.LoadUint64(&coldCounts.buckets[i])) - atomic.StoreUint64(&coldCounts.buckets[i], 0) - } - return nil -} - -// findBucket returns the index of the bucket for the provided value, or -// len(h.upperBounds) for the +Inf bucket. -func (h *histogram) findBucket(v float64) int { - // TODO(beorn7): For small numbers of buckets (<30), a linear search is - // slightly faster than the binary search. If we really care, we could - // switch from one search strategy to the other depending on the number - // of buckets. - // - // Microbenchmarks (BenchmarkHistogramNoLabels): - // 11 buckets: 38.3 ns/op linear - binary 48.7 ns/op - // 100 buckets: 78.1 ns/op linear - binary 54.9 ns/op - // 300 buckets: 154 ns/op linear - binary 61.6 ns/op - return sort.SearchFloat64s(h.upperBounds, v) -} - -// observe is the implementation for Observe without the findBucket part. -func (h *histogram) observe(v float64, bucket int) { - // We increment h.countAndHotIdx so that the counter in the lower - // 63 bits gets incremented. At the same time, we get the new value - // back, which we can use to find the currently-hot counts. - n := atomic.AddUint64(&h.countAndHotIdx, 1) - hotCounts := h.counts[n>>63] - - if bucket < len(h.upperBounds) { - atomic.AddUint64(&hotCounts.buckets[bucket], 1) - } - for { - oldBits := atomic.LoadUint64(&hotCounts.sumBits) - newBits := math.Float64bits(math.Float64frombits(oldBits) + v) - if atomic.CompareAndSwapUint64(&hotCounts.sumBits, oldBits, newBits) { - break - } - } - // Increment count last as we take it as a signal that the observation - // is complete. - atomic.AddUint64(&hotCounts.count, 1) -} - -// updateExemplar replaces the exemplar for the provided bucket. With empty -// labels, it's a no-op. It panics if any of the labels is invalid. -func (h *histogram) updateExemplar(v float64, bucket int, l Labels) { - if l == nil { - return - } - e, err := newExemplar(v, h.now(), l) - if err != nil { - panic(err) - } - h.exemplars[bucket].Store(e) -} - -// HistogramVec is a Collector that bundles a set of Histograms that all share the -// same Desc, but have different values for their variable labels. This is used -// if you want to count the same thing partitioned by various dimensions -// (e.g. HTTP request latencies, partitioned by status code and method). Create -// instances with NewHistogramVec. -type HistogramVec struct { - *MetricVec -} - -// NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and -// partitioned by the given label names. -func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec { - desc := NewDesc( - BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), - opts.Help, - labelNames, - opts.ConstLabels, - ) - return &HistogramVec{ - MetricVec: NewMetricVec(desc, func(lvs ...string) Metric { - return newHistogram(desc, opts, lvs...) - }), - } -} - -// GetMetricWithLabelValues returns the Histogram for the given slice of label -// values (same order as the variable labels in Desc). If that combination of -// label values is accessed for the first time, a new Histogram is created. -// -// It is possible to call this method without using the returned Histogram to only -// create the new Histogram but leave it at its starting value, a Histogram without -// any observations. -// -// Keeping the Histogram for later use is possible (and should be considered if -// performance is critical), but keep in mind that Reset, DeleteLabelValues and -// Delete can be used to delete the Histogram from the HistogramVec. In that case, the -// Histogram will still exist, but it will not be exported anymore, even if a -// Histogram with the same label values is created later. See also the CounterVec -// example. -// -// An error is returned if the number of label values is not the same as the -// number of variable labels in Desc (minus any curried labels). -// -// Note that for more than one label value, this method is prone to mistakes -// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as -// an alternative to avoid that type of mistake. For higher label numbers, the -// latter has a much more readable (albeit more verbose) syntax, but it comes -// with a performance overhead (for creating and processing the Labels map). -// See also the GaugeVec example. -func (v *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) { - metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...) - if metric != nil { - return metric.(Observer), err - } - return nil, err -} - -// GetMetricWith returns the Histogram for the given Labels map (the label names -// must match those of the variable labels in Desc). If that label map is -// accessed for the first time, a new Histogram is created. Implications of -// creating a Histogram without using it and keeping the Histogram for later use -// are the same as for GetMetricWithLabelValues. -// -// An error is returned if the number and names of the Labels are inconsistent -// with those of the variable labels in Desc (minus any curried labels). -// -// This method is used for the same purpose as -// GetMetricWithLabelValues(...string). See there for pros and cons of the two -// methods. -func (v *HistogramVec) GetMetricWith(labels Labels) (Observer, error) { - metric, err := v.MetricVec.GetMetricWith(labels) - if metric != nil { - return metric.(Observer), err - } - return nil, err -} - -// WithLabelValues works as GetMetricWithLabelValues, but panics where -// GetMetricWithLabelValues would have returned an error. Not returning an -// error allows shortcuts like -// myVec.WithLabelValues("404", "GET").Observe(42.21) -func (v *HistogramVec) WithLabelValues(lvs ...string) Observer { - h, err := v.GetMetricWithLabelValues(lvs...) - if err != nil { - panic(err) - } - return h -} - -// With works as GetMetricWith but panics where GetMetricWithLabels would have -// returned an error. Not returning an error allows shortcuts like -// myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Observe(42.21) -func (v *HistogramVec) With(labels Labels) Observer { - h, err := v.GetMetricWith(labels) - if err != nil { - panic(err) - } - return h -} - -// CurryWith returns a vector curried with the provided labels, i.e. the -// returned vector has those labels pre-set for all labeled operations performed -// on it. The cardinality of the curried vector is reduced accordingly. The -// order of the remaining labels stays the same (just with the curried labels -// taken out of the sequence – which is relevant for the -// (GetMetric)WithLabelValues methods). It is possible to curry a curried -// vector, but only with labels not yet used for currying before. -// -// The metrics contained in the HistogramVec are shared between the curried and -// uncurried vectors. They are just accessed differently. Curried and uncurried -// vectors behave identically in terms of collection. Only one must be -// registered with a given registry (usually the uncurried version). The Reset -// method deletes all metrics, even if called on a curried vector. -func (v *HistogramVec) CurryWith(labels Labels) (ObserverVec, error) { - vec, err := v.MetricVec.CurryWith(labels) - if vec != nil { - return &HistogramVec{vec}, err - } - return nil, err -} - -// MustCurryWith works as CurryWith but panics where CurryWith would have -// returned an error. -func (v *HistogramVec) MustCurryWith(labels Labels) ObserverVec { - vec, err := v.CurryWith(labels) - if err != nil { - panic(err) - } - return vec -} - -type constHistogram struct { - desc *Desc - count uint64 - sum float64 - buckets map[float64]uint64 - labelPairs []*dto.LabelPair -} - -func (h *constHistogram) Desc() *Desc { - return h.desc -} - -func (h *constHistogram) Write(out *dto.Metric) error { - his := &dto.Histogram{} - buckets := make([]*dto.Bucket, 0, len(h.buckets)) - - his.SampleCount = proto.Uint64(h.count) - his.SampleSum = proto.Float64(h.sum) - - for upperBound, count := range h.buckets { - buckets = append(buckets, &dto.Bucket{ - CumulativeCount: proto.Uint64(count), - UpperBound: proto.Float64(upperBound), - }) - } - - if len(buckets) > 0 { - sort.Sort(buckSort(buckets)) - } - his.Bucket = buckets - - out.Histogram = his - out.Label = h.labelPairs - - return nil -} - -// NewConstHistogram returns a metric representing a Prometheus histogram with -// fixed values for the count, sum, and bucket counts. As those parameters -// cannot be changed, the returned value does not implement the Histogram -// interface (but only the Metric interface). Users of this package will not -// have much use for it in regular operations. However, when implementing custom -// Collectors, it is useful as a throw-away metric that is generated on the fly -// to send it to Prometheus in the Collect method. -// -// buckets is a map of upper bounds to cumulative counts, excluding the +Inf -// bucket. -// -// NewConstHistogram returns an error if the length of labelValues is not -// consistent with the variable labels in Desc or if Desc is invalid. -func NewConstHistogram( - desc *Desc, - count uint64, - sum float64, - buckets map[float64]uint64, - labelValues ...string, -) (Metric, error) { - if desc.err != nil { - return nil, desc.err - } - if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil { - return nil, err - } - return &constHistogram{ - desc: desc, - count: count, - sum: sum, - buckets: buckets, - labelPairs: MakeLabelPairs(desc, labelValues), - }, nil -} - -// MustNewConstHistogram is a version of NewConstHistogram that panics where -// NewConstHistogram would have returned an error. -func MustNewConstHistogram( - desc *Desc, - count uint64, - sum float64, - buckets map[float64]uint64, - labelValues ...string, -) Metric { - m, err := NewConstHistogram(desc, count, sum, buckets, labelValues...) - if err != nil { - panic(err) - } - return m -} - -type buckSort []*dto.Bucket - -func (s buckSort) Len() int { - return len(s) -} - -func (s buckSort) Swap(i, j int) { - s[i], s[j] = s[j], s[i] -} - -func (s buckSort) Less(i, j int) bool { - return s[i].GetUpperBound() < s[j].GetUpperBound() -} |