From ed8bc523fd0d1a66acf3fa449c453508035efdfc Mon Sep 17 00:00:00 2001 From: Kevin Lyda Date: Sun, 12 Feb 2017 14:38:12 +0000 Subject: Initial pass at prometheus support. (#56) --- .../prometheus/client_golang/prometheus/summary.go | 543 +++++++++++++++++++++ 1 file changed, 543 insertions(+) create mode 100644 vendor/github.com/prometheus/client_golang/prometheus/summary.go (limited to 'vendor/github.com/prometheus/client_golang/prometheus/summary.go') diff --git a/vendor/github.com/prometheus/client_golang/prometheus/summary.go b/vendor/github.com/prometheus/client_golang/prometheus/summary.go new file mode 100644 index 0000000..82b8850 --- /dev/null +++ b/vendor/github.com/prometheus/client_golang/prometheus/summary.go @@ -0,0 +1,543 @@ +// Copyright 2014 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" + "sort" + "sync" + "time" + + "github.com/beorn7/perks/quantile" + "github.com/golang/protobuf/proto" + + dto "github.com/prometheus/client_model/go" +) + +// quantileLabel is used for the label that defines the quantile in a +// summary. +const quantileLabel = "quantile" + +// A Summary captures individual observations from an event or sample stream and +// summarizes them in a manner similar to traditional summary statistics: 1. sum +// of observations, 2. observation count, 3. rank estimations. +// +// A typical use-case is the observation of request latencies. By default, a +// Summary provides the median, the 90th and the 99th percentile of the latency +// as rank estimations. +// +// Note that the rank estimations cannot be aggregated in a meaningful way with +// the Prometheus query language (i.e. you cannot average or add them). If you +// need aggregatable quantiles (e.g. you want the 99th percentile latency of all +// queries served across all instances of a service), consider the Histogram +// metric type. See the Prometheus documentation for more details. +// +// To create Summary instances, use NewSummary. +type Summary interface { + Metric + Collector + + // Observe adds a single observation to the summary. + Observe(float64) +} + +// DefObjectives are the default Summary quantile values. +// +// Deprecated: DefObjectives will not be used as the default objectives in +// v0.10 of the library. The default Summary will have no quantiles then. +var ( + DefObjectives = map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001} + + errQuantileLabelNotAllowed = fmt.Errorf( + "%q is not allowed as label name in summaries", quantileLabel, + ) +) + +// Default values for SummaryOpts. +const ( + // DefMaxAge is the default duration for which observations stay + // relevant. + DefMaxAge time.Duration = 10 * time.Minute + // DefAgeBuckets is the default number of buckets used to calculate the + // age of observations. + DefAgeBuckets = 5 + // DefBufCap is the standard buffer size for collecting Summary observations. + DefBufCap = 500 +) + +// SummaryOpts bundles the options for creating a Summary metric. It is +// mandatory to set Name and Help to a non-empty string. All other fields are +// optional and can safely be left at their zero value. +type SummaryOpts struct { + // Namespace, Subsystem, and Name are components of the fully-qualified + // name of the Summary (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 Summary must be a + // valid Prometheus metric name. + Namespace string + Subsystem string + Name string + + // Help provides information about this Summary. Mandatory! + // + // Metrics with the same fully-qualified name must have the same Help + // string. + Help string + + // ConstLabels are used to attach fixed labels to this + // Summary. Summaries with the same fully-qualified name must have the + // same label names in their ConstLabels. + // + // Note that in most cases, labels have a value that varies during the + // lifetime of a process. Those labels are usually managed with a + // SummaryVec. ConstLabels serve only special purposes. One is for the + // special case where the value of a label does not change during the + // lifetime of a process, e.g. if the revision of the running binary is + // put into a label. Another, more advanced purpose is if more than one + // Collector needs to collect Summaries with the same fully-qualified + // name. In that case, those Summaries must differ in the values of + // their ConstLabels. See the Collector examples. + // + // If the value of a label never changes (not even between binaries), + // that label most likely should not be a label at all (but part of the + // metric name). + ConstLabels Labels + + // Objectives defines the quantile rank estimates with their respective + // absolute error. If Objectives[q] = e, then the value reported for q + // will be the φ-quantile value for some φ between q-e and q+e. The + // default value is DefObjectives. It is used if Objectives is left at + // its zero value (i.e. nil). To create a Summary without Objectives, + // set it to an empty map (i.e. map[float64]float64{}). + // + // Deprecated: Note that the current value of DefObjectives is + // deprecated. It will be replaced by an empty map in v0.10 of the + // library. Please explicitly set Objectives to the desired value. + Objectives map[float64]float64 + + // MaxAge defines the duration for which an observation stays relevant + // for the summary. Must be positive. The default value is DefMaxAge. + MaxAge time.Duration + + // AgeBuckets is the number of buckets used to exclude observations that + // are older than MaxAge from the summary. A higher number has a + // resource penalty, so only increase it if the higher resolution is + // really required. For very high observation rates, you might want to + // reduce the number of age buckets. With only one age bucket, you will + // effectively see a complete reset of the summary each time MaxAge has + // passed. The default value is DefAgeBuckets. + AgeBuckets uint32 + + // BufCap defines the default sample stream buffer size. The default + // value of DefBufCap should suffice for most uses. If there is a need + // to increase the value, a multiple of 500 is recommended (because that + // is the internal buffer size of the underlying package + // "github.com/bmizerany/perks/quantile"). + BufCap uint32 +} + +// Great fuck-up with the sliding-window decay algorithm... The Merge method of +// perk/quantile is actually not working as advertised - and it might be +// unfixable, as the underlying algorithm is apparently not capable of merging +// summaries in the first place. To avoid using Merge, we are currently adding +// observations to _each_ age bucket, i.e. the effort to add a sample is +// essentially multiplied by the number of age buckets. When rotating age +// buckets, we empty the previous head stream. On scrape time, we simply take +// the quantiles from the head stream (no merging required). Result: More effort +// on observation time, less effort on scrape time, which is exactly the +// opposite of what we try to accomplish, but at least the results are correct. +// +// The quite elegant previous contraption to merge the age buckets efficiently +// on scrape time (see code up commit 6b9530d72ea715f0ba612c0120e6e09fbf1d49d0) +// can't be used anymore. + +// NewSummary creates a new Summary based on the provided SummaryOpts. +func NewSummary(opts SummaryOpts) Summary { + return newSummary( + NewDesc( + BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), + opts.Help, + nil, + opts.ConstLabels, + ), + opts, + ) +} + +func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary { + if len(desc.variableLabels) != len(labelValues) { + panic(errInconsistentCardinality) + } + + for _, n := range desc.variableLabels { + if n == quantileLabel { + panic(errQuantileLabelNotAllowed) + } + } + for _, lp := range desc.constLabelPairs { + if lp.GetName() == quantileLabel { + panic(errQuantileLabelNotAllowed) + } + } + + if opts.Objectives == nil { + opts.Objectives = DefObjectives + } + + if opts.MaxAge < 0 { + panic(fmt.Errorf("illegal max age MaxAge=%v", opts.MaxAge)) + } + if opts.MaxAge == 0 { + opts.MaxAge = DefMaxAge + } + + if opts.AgeBuckets == 0 { + opts.AgeBuckets = DefAgeBuckets + } + + if opts.BufCap == 0 { + opts.BufCap = DefBufCap + } + + s := &summary{ + desc: desc, + + objectives: opts.Objectives, + sortedObjectives: make([]float64, 0, len(opts.Objectives)), + + labelPairs: makeLabelPairs(desc, labelValues), + + hotBuf: make([]float64, 0, opts.BufCap), + coldBuf: make([]float64, 0, opts.BufCap), + streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets), + } + s.headStreamExpTime = time.Now().Add(s.streamDuration) + s.hotBufExpTime = s.headStreamExpTime + + for i := uint32(0); i < opts.AgeBuckets; i++ { + s.streams = append(s.streams, s.newStream()) + } + s.headStream = s.streams[0] + + for qu := range s.objectives { + s.sortedObjectives = append(s.sortedObjectives, qu) + } + sort.Float64s(s.sortedObjectives) + + s.init(s) // Init self-collection. + return s +} + +type summary struct { + selfCollector + + bufMtx sync.Mutex // Protects hotBuf and hotBufExpTime. + mtx sync.Mutex // Protects every other moving part. + // Lock bufMtx before mtx if both are needed. + + desc *Desc + + objectives map[float64]float64 + sortedObjectives []float64 + + labelPairs []*dto.LabelPair + + sum float64 + cnt uint64 + + hotBuf, coldBuf []float64 + + streams []*quantile.Stream + streamDuration time.Duration + headStream *quantile.Stream + headStreamIdx int + headStreamExpTime, hotBufExpTime time.Time +} + +func (s *summary) Desc() *Desc { + return s.desc +} + +func (s *summary) Observe(v float64) { + s.bufMtx.Lock() + defer s.bufMtx.Unlock() + + now := time.Now() + if now.After(s.hotBufExpTime) { + s.asyncFlush(now) + } + s.hotBuf = append(s.hotBuf, v) + if len(s.hotBuf) == cap(s.hotBuf) { + s.asyncFlush(now) + } +} + +func (s *summary) Write(out *dto.Metric) error { + sum := &dto.Summary{} + qs := make([]*dto.Quantile, 0, len(s.objectives)) + + s.bufMtx.Lock() + s.mtx.Lock() + // Swap bufs even if hotBuf is empty to set new hotBufExpTime. + s.swapBufs(time.Now()) + s.bufMtx.Unlock() + + s.flushColdBuf() + sum.SampleCount = proto.Uint64(s.cnt) + sum.SampleSum = proto.Float64(s.sum) + + for _, rank := range s.sortedObjectives { + var q float64 + if s.headStream.Count() == 0 { + q = math.NaN() + } else { + q = s.headStream.Query(rank) + } + qs = append(qs, &dto.Quantile{ + Quantile: proto.Float64(rank), + Value: proto.Float64(q), + }) + } + + s.mtx.Unlock() + + if len(qs) > 0 { + sort.Sort(quantSort(qs)) + } + sum.Quantile = qs + + out.Summary = sum + out.Label = s.labelPairs + return nil +} + +func (s *summary) newStream() *quantile.Stream { + return quantile.NewTargeted(s.objectives) +} + +// asyncFlush needs bufMtx locked. +func (s *summary) asyncFlush(now time.Time) { + s.mtx.Lock() + s.swapBufs(now) + + // Unblock the original goroutine that was responsible for the mutation + // that triggered the compaction. But hold onto the global non-buffer + // state mutex until the operation finishes. + go func() { + s.flushColdBuf() + s.mtx.Unlock() + }() +} + +// rotateStreams needs mtx AND bufMtx locked. +func (s *summary) maybeRotateStreams() { + for !s.hotBufExpTime.Equal(s.headStreamExpTime) { + s.headStream.Reset() + s.headStreamIdx++ + if s.headStreamIdx >= len(s.streams) { + s.headStreamIdx = 0 + } + s.headStream = s.streams[s.headStreamIdx] + s.headStreamExpTime = s.headStreamExpTime.Add(s.streamDuration) + } +} + +// flushColdBuf needs mtx locked. +func (s *summary) flushColdBuf() { + for _, v := range s.coldBuf { + for _, stream := range s.streams { + stream.Insert(v) + } + s.cnt++ + s.sum += v + } + s.coldBuf = s.coldBuf[0:0] + s.maybeRotateStreams() +} + +// swapBufs needs mtx AND bufMtx locked, coldBuf must be empty. +func (s *summary) swapBufs(now time.Time) { + if len(s.coldBuf) != 0 { + panic("coldBuf is not empty") + } + s.hotBuf, s.coldBuf = s.coldBuf, s.hotBuf + // hotBuf is now empty and gets new expiration set. + for now.After(s.hotBufExpTime) { + s.hotBufExpTime = s.hotBufExpTime.Add(s.streamDuration) + } +} + +type quantSort []*dto.Quantile + +func (s quantSort) Len() int { + return len(s) +} + +func (s quantSort) Swap(i, j int) { + s[i], s[j] = s[j], s[i] +} + +func (s quantSort) Less(i, j int) bool { + return s[i].GetQuantile() < s[j].GetQuantile() +} + +// SummaryVec is a Collector that bundles a set of Summaries 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 NewSummaryVec. +type SummaryVec struct { + *MetricVec +} + +// NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and +// partitioned by the given label names. At least one label name must be +// provided. +func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec { + desc := NewDesc( + BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), + opts.Help, + labelNames, + opts.ConstLabels, + ) + return &SummaryVec{ + MetricVec: newMetricVec(desc, func(lvs ...string) Metric { + return newSummary(desc, opts, lvs...) + }), + } +} + +// GetMetricWithLabelValues replaces the method of the same name in +// MetricVec. The difference is that this method returns a Summary and not a +// Metric so that no type conversion is required. +func (m *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Summary, error) { + metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...) + if metric != nil { + return metric.(Summary), err + } + return nil, err +} + +// GetMetricWith replaces the method of the same name in MetricVec. The +// difference is that this method returns a Summary and not a Metric so that no +// type conversion is required. +func (m *SummaryVec) GetMetricWith(labels Labels) (Summary, error) { + metric, err := m.MetricVec.GetMetricWith(labels) + if metric != nil { + return metric.(Summary), err + } + return nil, err +} + +// WithLabelValues works as GetMetricWithLabelValues, but panics where +// GetMetricWithLabelValues would have returned an error. By not returning an +// error, WithLabelValues allows shortcuts like +// myVec.WithLabelValues("404", "GET").Observe(42.21) +func (m *SummaryVec) WithLabelValues(lvs ...string) Summary { + return m.MetricVec.WithLabelValues(lvs...).(Summary) +} + +// With works as GetMetricWith, but panics where GetMetricWithLabels would have +// returned an error. By not returning an error, With allows shortcuts like +// myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21) +func (m *SummaryVec) With(labels Labels) Summary { + return m.MetricVec.With(labels).(Summary) +} + +type constSummary struct { + desc *Desc + count uint64 + sum float64 + quantiles map[float64]float64 + labelPairs []*dto.LabelPair +} + +func (s *constSummary) Desc() *Desc { + return s.desc +} + +func (s *constSummary) Write(out *dto.Metric) error { + sum := &dto.Summary{} + qs := make([]*dto.Quantile, 0, len(s.quantiles)) + + sum.SampleCount = proto.Uint64(s.count) + sum.SampleSum = proto.Float64(s.sum) + + for rank, q := range s.quantiles { + qs = append(qs, &dto.Quantile{ + Quantile: proto.Float64(rank), + Value: proto.Float64(q), + }) + } + + if len(qs) > 0 { + sort.Sort(quantSort(qs)) + } + sum.Quantile = qs + + out.Summary = sum + out.Label = s.labelPairs + + return nil +} + +// NewConstSummary returns a metric representing a Prometheus summary with fixed +// values for the count, sum, and quantiles. As those parameters cannot be +// changed, the returned value does not implement the Summary 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. +// +// quantiles maps ranks to quantile values. For example, a median latency of +// 0.23s and a 99th percentile latency of 0.56s would be expressed as: +// map[float64]float64{0.5: 0.23, 0.99: 0.56} +// +// NewConstSummary returns an error if the length of labelValues is not +// consistent with the variable labels in Desc. +func NewConstSummary( + desc *Desc, + count uint64, + sum float64, + quantiles map[float64]float64, + labelValues ...string, +) (Metric, error) { + if len(desc.variableLabels) != len(labelValues) { + return nil, errInconsistentCardinality + } + return &constSummary{ + desc: desc, + count: count, + sum: sum, + quantiles: quantiles, + labelPairs: makeLabelPairs(desc, labelValues), + }, nil +} + +// MustNewConstSummary is a version of NewConstSummary that panics where +// NewConstMetric would have returned an error. +func MustNewConstSummary( + desc *Desc, + count uint64, + sum float64, + quantiles map[float64]float64, + labelValues ...string, +) Metric { + m, err := NewConstSummary(desc, count, sum, quantiles, labelValues...) + if err != nil { + panic(err) + } + return m +} -- cgit v1.2.3