Update dependencies

vendor/github.com/prometheus/client_golang/NOTICE

@@ -16,8 +16,3 @@ Go support for Protocol Buffers - Google's data interchange format
 http://github.com/golang/protobuf/
 Copyright 2010 The Go Authors
 See source code for license details.
-
-Support for streaming Protocol Buffer messages for the Go language (golang).
-https://github.com/matttproud/golang_protobuf_extensions
-Copyright 2013 Matt T. Proud
-Licensed under the Apache License, Version 2.0

vendor/github.com/prometheus/client_golang/prometheus/collectorfunc.go

@@ -0,0 +1,30 @@
+// Copyright 2025 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
+
+// CollectorFunc is a convenient way to implement a Prometheus Collector
+// without interface boilerplate.
+// This implementation is based on DescribeByCollect method.
+// familiarize yourself to it before using.
+type CollectorFunc func(chan<- Metric)
+
+// Collect calls the defined CollectorFunc function with the provided Metrics channel
+func (f CollectorFunc) Collect(ch chan<- Metric) {
+	f(ch)
+}
+
+// Describe sends the descriptor information using DescribeByCollect
+func (f CollectorFunc) Describe(ch chan<- *Desc) {
+	DescribeByCollect(f, ch)
+}

vendor/github.com/prometheus/client_golang/prometheus/counter.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	dto "github.com/prometheus/client_model/go"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // Counter is a Metric that represents a single numerical value that only ever
@@ -66,7 +67,7 @@ type CounterVecOpts struct {
 	CounterOpts
 
 	// VariableLabels are used to partition the metric vector by the given set
-	// of labels. Each label value will be constrained with the optional Contraint
+	// of labels. Each label value will be constrained with the optional Constraint
 	// function, if provided.
 	VariableLabels ConstrainableLabels
 }
@@ -90,8 +91,12 @@ func NewCounter(opts CounterOpts) Counter {
 		nil,
 		opts.ConstLabels,
 	)
-	result := &counter{desc: desc, labelPairs: desc.constLabelPairs, now: time.Now}
+	if opts.now == nil {
+		opts.now = time.Now
+	}
+	result := &counter{desc: desc, labelPairs: desc.constLabelPairs, now: opts.now}
 	result.init(result) // Init self-collection.
+	result.createdTs = timestamppb.New(opts.now())
 	return result
 }
 
@@ -106,10 +111,12 @@ type counter struct {
 	selfCollector
 	desc *Desc
 
+	createdTs  *timestamppb.Timestamp
 	labelPairs []*dto.LabelPair
 	exemplar   atomic.Value // Containing nil or a *dto.Exemplar.
 
-	now func() time.Time // To mock out time.Now() for testing.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 func (c *counter) Desc() *Desc {
@@ -159,8 +166,7 @@ func (c *counter) Write(out *dto.Metric) error {
 		exemplar = e.(*dto.Exemplar)
 	}
 	val := c.get()
-
-	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out)
+	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out, c.createdTs)
 }
 
 func (c *counter) updateExemplar(v float64, l Labels) {
@@ -200,13 +206,17 @@ func (v2) NewCounterVec(opts CounterVecOpts) *CounterVec {
 		opts.VariableLabels,
 		opts.ConstLabels,
 	)
+	if opts.now == nil {
+		opts.now = time.Now
+	}
 	return &CounterVec{
 		MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
-			if len(lvs) != len(desc.variableLabels) {
-				panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.labelNames(), lvs))
+			if len(lvs) != len(desc.variableLabels.names) {
+				panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, lvs))
 			}
-			result := &counter{desc: desc, labelPairs: MakeLabelPairs(desc, lvs), now: time.Now}
+			result := &counter{desc: desc, labelPairs: MakeLabelPairs(desc, lvs), now: opts.now}
 			result.init(result) // Init self-collection.
+			result.createdTs = timestamppb.New(opts.now())
 			return result
 		}),
 	}

vendor/github.com/prometheus/client_golang/prometheus/desc.go

@@ -18,12 +18,12 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/prometheus/client_golang/prometheus/internal"
-
 	"github.com/cespare/xxhash/v2"
 	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/model"
 	"google.golang.org/protobuf/proto"
+
+	"github.com/prometheus/client_golang/prometheus/internal"
 )
 
 // Desc is the descriptor used by every Prometheus Metric. It is essentially
@@ -52,7 +52,7 @@ type Desc struct {
 	constLabelPairs []*dto.LabelPair
 	// variableLabels contains names of labels and normalization function for
 	// which the metric maintains variable values.
-	variableLabels ConstrainedLabels
+	variableLabels *compiledLabels
 	// id is a hash of the values of the ConstLabels and fqName. This
 	// must be unique among all registered descriptors and can therefore be
 	// used as an identifier of the descriptor.
@@ -93,9 +93,10 @@ func (v2) NewDesc(fqName, help string, variableLabels ConstrainableLabels, const
 	d := &Desc{
 		fqName:         fqName,
 		help:           help,
-		variableLabels: variableLabels.constrainedLabels(),
+		variableLabels: variableLabels.compile(),
 	}
-	if !model.IsValidMetricName(model.LabelValue(fqName)) {
+	//nolint:staticcheck // TODO: Don't use deprecated model.NameValidationScheme.
+	if !model.NameValidationScheme.IsValidMetricName(fqName) {
 		d.err = fmt.Errorf("%q is not a valid metric name", fqName)
 		return d
 	}
@@ -103,7 +104,7 @@ func (v2) NewDesc(fqName, help string, variableLabels ConstrainableLabels, const
 	// their sorted label names) plus the fqName (at position 0).
 	labelValues := make([]string, 1, len(constLabels)+1)
 	labelValues[0] = fqName
-	labelNames := make([]string, 0, len(constLabels)+len(d.variableLabels))
+	labelNames := make([]string, 0, len(constLabels)+len(d.variableLabels.names))
 	labelNameSet := map[string]struct{}{}
 	// First add only the const label names and sort them...
 	for labelName := range constLabels {
@@ -128,13 +129,13 @@ func (v2) NewDesc(fqName, help string, variableLabels ConstrainableLabels, const
 	// Now add the variable label names, but prefix them with something that
 	// cannot be in a regular label name. That prevents matching the label
 	// dimension with a different mix between preset and variable labels.
-	for _, label := range d.variableLabels {
-		if !checkLabelName(label.Name) {
-			d.err = fmt.Errorf("%q is not a valid label name for metric %q", label.Name, fqName)
+	for _, label := range d.variableLabels.names {
+		if !checkLabelName(label) {
+			d.err = fmt.Errorf("%q is not a valid label name for metric %q", label, fqName)
 			return d
 		}
-		labelNames = append(labelNames, "$"+label.Name)
-		labelNameSet[label.Name] = struct{}{}
+		labelNames = append(labelNames, "$"+label)
+		labelNameSet[label] = struct{}{}
 	}
 	if len(labelNames) != len(labelNameSet) {
 		d.err = fmt.Errorf("duplicate label names in constant and variable labels for metric %q", fqName)
@@ -189,11 +190,22 @@ func (d *Desc) String() string {
 			fmt.Sprintf("%s=%q", lp.GetName(), lp.GetValue()),
 		)
 	}
+	vlStrings := []string{}
+	if d.variableLabels != nil {
+		vlStrings = make([]string, 0, len(d.variableLabels.names))
+		for _, vl := range d.variableLabels.names {
+			if fn, ok := d.variableLabels.labelConstraints[vl]; ok && fn != nil {
+				vlStrings = append(vlStrings, fmt.Sprintf("c(%s)", vl))
+			} else {
+				vlStrings = append(vlStrings, vl)
+			}
+		}
+	}
 	return fmt.Sprintf(
-		"Desc{fqName: %q, help: %q, constLabels: {%s}, variableLabels: %v}",
+		"Desc{fqName: %q, help: %q, constLabels: {%s}, variableLabels: {%s}}",
 		d.fqName,
 		d.help,
 		strings.Join(lpStrings, ","),
-		d.variableLabels,
+		strings.Join(vlStrings, ","),
 	)
 }

vendor/github.com/prometheus/client_golang/prometheus/expvar_collector.go

@@ -48,7 +48,7 @@ func (e *expvarCollector) Collect(ch chan<- Metric) {
 			continue
 		}
 		var v interface{}
-		labels := make([]string, len(desc.variableLabels))
+		labels := make([]string, len(desc.variableLabels.names))
 		if err := json.Unmarshal([]byte(expVar.String()), &v); err != nil {
 			ch <- NewInvalidMetric(desc, err)
 			continue

vendor/github.com/prometheus/client_golang/prometheus/gauge.go

@@ -62,7 +62,7 @@ type GaugeVecOpts struct {
 	GaugeOpts
 
 	// VariableLabels are used to partition the metric vector by the given set
-	// of labels. Each label value will be constrained with the optional Contraint
+	// of labels. Each label value will be constrained with the optional Constraint
 	// function, if provided.
 	VariableLabels ConstrainableLabels
 }
@@ -135,7 +135,7 @@ func (g *gauge) Sub(val float64) {
 
 func (g *gauge) Write(out *dto.Metric) error {
 	val := math.Float64frombits(atomic.LoadUint64(&g.valBits))
-	return populateMetric(GaugeValue, val, g.labelPairs, nil, out)
+	return populateMetric(GaugeValue, val, g.labelPairs, nil, out, nil)
 }
 
 // GaugeVec is a Collector that bundles a set of Gauges that all share the same
@@ -166,8 +166,8 @@ func (v2) NewGaugeVec(opts GaugeVecOpts) *GaugeVec {
 	)
 	return &GaugeVec{
 		MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
-			if len(lvs) != len(desc.variableLabels) {
-				panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.labelNames(), lvs))
+			if len(lvs) != len(desc.variableLabels.names) {
+				panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, lvs))
 			}
 			result := &gauge{desc: desc, labelPairs: MakeLabelPairs(desc, lvs)}
 			result.init(result) // Init self-collection.

vendor/github.com/prometheus/client_golang/prometheus/go_collector.go

@@ -22,13 +22,13 @@ import (
 // goRuntimeMemStats provides the metrics initially provided by runtime.ReadMemStats.
 // From Go 1.17 those similar (and better) statistics are provided by runtime/metrics, so
 // while eval closure works on runtime.MemStats, the struct from Go 1.17+ is
-// populated using runtime/metrics.
+// populated using runtime/metrics. Those are the defaults we can't alter.
 func goRuntimeMemStats() memStatsMetrics {
 	return memStatsMetrics{
 		{
 			desc: NewDesc(
 				memstatNamespace("alloc_bytes"),
-				"Number of bytes allocated and still in use.",
+				"Number of bytes allocated in heap and currently in use. Equals to /memory/classes/heap/objects:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Alloc) },
@@ -36,7 +36,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("alloc_bytes_total"),
-				"Total number of bytes allocated, even if freed.",
+				"Total number of bytes allocated in heap until now, even if released already. Equals to /gc/heap/allocs:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.TotalAlloc) },
@@ -44,23 +44,16 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("sys_bytes"),
-				"Number of bytes obtained from system.",
+				"Number of bytes obtained from system. Equals to /memory/classes/total:byte.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Sys) },
 			valType: GaugeValue,
-		}, {
-			desc: NewDesc(
-				memstatNamespace("lookups_total"),
-				"Total number of pointer lookups.",
-				nil, nil,
-			),
-			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Lookups) },
-			valType: CounterValue,
 		}, {
 			desc: NewDesc(
 				memstatNamespace("mallocs_total"),
-				"Total number of mallocs.",
+				// TODO(bwplotka): We could add go_memstats_heap_objects, probably useful for discovery. Let's gather more feedback, kind of a waste of bytes for everybody for compatibility reasons to keep both, and we can't really rename/remove useful metric.
+				"Total number of heap objects allocated, both live and gc-ed. Semantically a counter version for go_memstats_heap_objects gauge. Equals to /gc/heap/allocs:objects + /gc/heap/tiny/allocs:objects.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Mallocs) },
@@ -68,7 +61,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("frees_total"),
-				"Total number of frees.",
+				"Total number of heap objects frees. Equals to /gc/heap/frees:objects + /gc/heap/tiny/allocs:objects.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Frees) },
@@ -76,7 +69,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_alloc_bytes"),
-				"Number of heap bytes allocated and still in use.",
+				"Number of heap bytes allocated and currently in use, same as go_memstats_alloc_bytes. Equals to /memory/classes/heap/objects:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapAlloc) },
@@ -84,7 +77,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_sys_bytes"),
-				"Number of heap bytes obtained from system.",
+				"Number of heap bytes obtained from system. Equals to /memory/classes/heap/objects:bytes + /memory/classes/heap/unused:bytes + /memory/classes/heap/released:bytes + /memory/classes/heap/free:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapSys) },
@@ -92,7 +85,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_idle_bytes"),
-				"Number of heap bytes waiting to be used.",
+				"Number of heap bytes waiting to be used. Equals to /memory/classes/heap/released:bytes + /memory/classes/heap/free:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapIdle) },
@@ -100,7 +93,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_inuse_bytes"),
-				"Number of heap bytes that are in use.",
+				"Number of heap bytes that are in use. Equals to /memory/classes/heap/objects:bytes + /memory/classes/heap/unused:bytes",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapInuse) },
@@ -108,7 +101,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_released_bytes"),
-				"Number of heap bytes released to OS.",
+				"Number of heap bytes released to OS. Equals to /memory/classes/heap/released:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapReleased) },
@@ -116,7 +109,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("heap_objects"),
-				"Number of allocated objects.",
+				"Number of currently allocated objects. Equals to /gc/heap/objects:objects.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapObjects) },
@@ -124,7 +117,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("stack_inuse_bytes"),
-				"Number of bytes in use by the stack allocator.",
+				"Number of bytes obtained from system for stack allocator in non-CGO environments. Equals to /memory/classes/heap/stacks:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackInuse) },
@@ -132,7 +125,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("stack_sys_bytes"),
-				"Number of bytes obtained from system for stack allocator.",
+				"Number of bytes obtained from system for stack allocator. Equals to /memory/classes/heap/stacks:bytes + /memory/classes/os-stacks:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackSys) },
@@ -140,7 +133,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("mspan_inuse_bytes"),
-				"Number of bytes in use by mspan structures.",
+				"Number of bytes in use by mspan structures. Equals to /memory/classes/metadata/mspan/inuse:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanInuse) },
@@ -148,7 +141,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("mspan_sys_bytes"),
-				"Number of bytes used for mspan structures obtained from system.",
+				"Number of bytes used for mspan structures obtained from system. Equals to /memory/classes/metadata/mspan/inuse:bytes + /memory/classes/metadata/mspan/free:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanSys) },
@@ -156,7 +149,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("mcache_inuse_bytes"),
-				"Number of bytes in use by mcache structures.",
+				"Number of bytes in use by mcache structures. Equals to /memory/classes/metadata/mcache/inuse:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheInuse) },
@@ -164,7 +157,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("mcache_sys_bytes"),
-				"Number of bytes used for mcache structures obtained from system.",
+				"Number of bytes used for mcache structures obtained from system. Equals to /memory/classes/metadata/mcache/inuse:bytes + /memory/classes/metadata/mcache/free:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheSys) },
@@ -172,7 +165,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("buck_hash_sys_bytes"),
-				"Number of bytes used by the profiling bucket hash table.",
+				"Number of bytes used by the profiling bucket hash table. Equals to /memory/classes/profiling/buckets:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.BuckHashSys) },
@@ -180,7 +173,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("gc_sys_bytes"),
-				"Number of bytes used for garbage collection system metadata.",
+				"Number of bytes used for garbage collection system metadata. Equals to /memory/classes/metadata/other:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.GCSys) },
@@ -188,7 +181,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("other_sys_bytes"),
-				"Number of bytes used for other system allocations.",
+				"Number of bytes used for other system allocations. Equals to /memory/classes/other:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.OtherSys) },
@@ -196,7 +189,7 @@ func goRuntimeMemStats() memStatsMetrics {
 		}, {
 			desc: NewDesc(
 				memstatNamespace("next_gc_bytes"),
-				"Number of heap bytes when next garbage collection will take place.",
+				"Number of heap bytes when next garbage collection will take place. Equals to /gc/heap/goal:bytes.",
 				nil, nil,
 			),
 			eval:    func(ms *runtime.MemStats) float64 { return float64(ms.NextGC) },
@@ -225,7 +218,7 @@ func newBaseGoCollector() baseGoCollector {
 			nil, nil),
 		gcDesc: NewDesc(
 			"go_gc_duration_seconds",
-			"A summary of the pause duration of garbage collection cycles.",
+			"A summary of the wall-time pause (stop-the-world) duration in garbage collection cycles.",
 			nil, nil),
 		gcLastTimeDesc: NewDesc(
 			"go_memstats_last_gc_time_seconds",

vendor/github.com/prometheus/client_golang/prometheus/go_collector_latest.go

@@ -17,6 +17,7 @@
 package prometheus
 
 import (
+	"fmt"
 	"math"
 	"runtime"
 	"runtime/metrics"
@@ -153,7 +154,8 @@ func defaultGoCollectorOptions() internal.GoCollectorOptions {
 			"/gc/heap/frees-by-size:bytes":  goGCHeapFreesBytes,
 		},
 		RuntimeMetricRules: []internal.GoCollectorRule{
-			//{Matcher: regexp.MustCompile("")},
+			// Recommended metrics we want by default from runtime/metrics.
+			{Matcher: internal.GoCollectorDefaultRuntimeMetrics},
 		},
 	}
 }
@@ -203,6 +205,7 @@ func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
 			// to fail here. This condition is tested in TestExpectedRuntimeMetrics.
 			continue
 		}
+		help := attachOriginalName(d.Description.Description, d.Name)
 
 		sampleBuf = append(sampleBuf, metrics.Sample{Name: d.Name})
 		sampleMap[d.Name] = &sampleBuf[len(sampleBuf)-1]
@@ -214,7 +217,7 @@ func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
 			m = newBatchHistogram(
 				NewDesc(
 					BuildFQName(namespace, subsystem, name),
-					d.Description.Description,
+					help,
 					nil,
 					nil,
 				),
@@ -226,7 +229,7 @@ func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
 				Namespace: namespace,
 				Subsystem: subsystem,
 				Name:      name,
-				Help:      d.Description.Description,
+				Help:      help,
 			},
 			)
 		} else {
@@ -234,7 +237,7 @@ func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
 				Namespace: namespace,
 				Subsystem: subsystem,
 				Name:      name,
-				Help:      d.Description.Description,
+				Help:      help,
 			})
 		}
 		metricSet = append(metricSet, m)
@@ -284,6 +287,10 @@ func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
 	}
 }
 
+func attachOriginalName(desc, origName string) string {
+	return fmt.Sprintf("%s Sourced from %s.", desc, origName)
+}
+
 // Describe returns all descriptions of the collector.
 func (c *goCollector) Describe(ch chan<- *Desc) {
 	c.base.Describe(ch)
@@ -376,13 +383,13 @@ func unwrapScalarRMValue(v metrics.Value) float64 {
 		//
 		// This should never happen because we always populate our metric
 		// set from the runtime/metrics package.
-		panic("unexpected unsupported metric")
+		panic("unexpected bad kind metric")
 	default:
 		// Unsupported metric kind.
 		//
 		// This should never happen because we check for this during initialization
 		// and flag and filter metrics whose kinds we don't understand.
-		panic("unexpected unsupported metric kind")
+		panic(fmt.Sprintf("unexpected unsupported metric: %v", v.Kind()))
 	}
 }
 

vendor/github.com/prometheus/client_golang/prometheus/histogram.go

@@ -14,6 +14,7 @@
 package prometheus
 
 import (
+	"errors"
 	"fmt"
 	"math"
 	"runtime"
@@ -25,6 +26,12 @@ import (
 	dto "github.com/prometheus/client_model/go"
 
 	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+const (
+	nativeHistogramSchemaMaximum = 8
+	nativeHistogramSchemaMinimum = -4
 )
 
 // nativeHistogramBounds for the frac of observed values. Only relevant for
@@ -329,11 +336,11 @@ func ExponentialBuckets(start, factor float64, count int) []float64 {
 // 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 {
+func ExponentialBucketsRange(minBucket, maxBucket float64, count int) []float64 {
 	if count < 1 {
 		panic("ExponentialBucketsRange count needs a positive count")
 	}
-	if min <= 0 {
+	if minBucket <= 0 {
 		panic("ExponentialBucketsRange min needs to be greater than 0")
 	}
 
@@ -341,12 +348,12 @@ func ExponentialBucketsRange(min, max float64, count int) []float64 {
 	// 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))
+	growthFactor := math.Pow(maxBucket/minBucket, 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))
+		buckets[i-1] = minBucket * math.Pow(growthFactor, float64(i-1))
 	}
 	return buckets
 }
@@ -391,7 +398,7 @@ type HistogramOpts struct {
 	// zero, it is replaced by default buckets. The default buckets are
 	// DefBuckets if no buckets for a native histogram (see below) are used,
 	// otherwise the default is no buckets. (In other words, if you want to
-	// use both reguler buckets and buckets for a native histogram, you have
+	// use both regular buckets and buckets for a native histogram, you have
 	// to define the regular buckets here explicitly.)
 	Buckets []float64
 
@@ -401,7 +408,7 @@ type HistogramOpts struct {
 	// Histogram by a Prometheus server with that feature enabled (requires
 	// Prometheus v2.40+). Sparse buckets are exponential buckets covering
 	// the whole float64 range (with the exception of the “zero” bucket, see
-	// SparseBucketsZeroThreshold below). From any one bucket to the next,
+	// NativeHistogramZeroThreshold below). From any one bucket to the next,
 	// the width of the bucket grows by a constant
 	// factor. NativeHistogramBucketFactor provides an upper bound for this
 	// factor (exception see below). The smaller
@@ -413,8 +420,8 @@ type HistogramOpts struct {
 	// and 2, same as between 2 and 4, and 4 and 8, etc.).
 	//
 	// Details about the actually used factor: The factor is calculated as
-	// 2^(2^n), where n is an integer number between (and including) -8 and
-	// 4. n is chosen so that the resulting factor is the largest that is
+	// 2^(2^-n), where n is an integer number between (and including) -4 and
+	// 8. n is chosen so that the resulting factor is the largest that is
 	// still smaller or equal to NativeHistogramBucketFactor. Note that the
 	// smallest possible factor is therefore approx. 1.00271 (i.e. 2^(2^-8)
 	// ). If NativeHistogramBucketFactor is greater than 1 but smaller than
@@ -428,44 +435,71 @@ type HistogramOpts struct {
 	// a major version bump.
 	NativeHistogramBucketFactor float64
 	// All observations with an absolute value of less or equal
-	// NativeHistogramZeroThreshold are accumulated into a “zero”
-	// bucket. For best results, this should be close to a bucket
-	// boundary. This is usually the case if picking a power of two. If
+	// NativeHistogramZeroThreshold are accumulated into a “zero” bucket.
+	// For best results, this should be close to a bucket boundary. This is
+	// usually the case if picking a power of two. If
 	// NativeHistogramZeroThreshold is left at zero,
-	// DefSparseBucketsZeroThreshold is used as the threshold. To configure
-	// a zero bucket with an actual threshold of zero (i.e. only
+	// DefNativeHistogramZeroThreshold is used as the threshold. To
+	// configure a zero bucket with an actual threshold of zero (i.e. only
 	// observations of precisely zero will go into the zero bucket), set
 	// NativeHistogramZeroThreshold to the NativeHistogramZeroThresholdZero
 	// constant (or any negative float value).
 	NativeHistogramZeroThreshold float64
 
-	// The remaining fields define a strategy to limit the number of
+	// The next three fields define a strategy to limit the number of
 	// populated sparse buckets. If NativeHistogramMaxBucketNumber is left
 	// at zero, the number of buckets is not limited. (Note that this might
 	// lead to unbounded memory consumption if the values observed by the
 	// Histogram are sufficiently wide-spread. In particular, this could be
 	// used as a DoS attack vector. Where the observed values depend on
 	// external inputs, it is highly recommended to set a
-	// NativeHistogramMaxBucketNumber.)  Once the set
+	// NativeHistogramMaxBucketNumber.) Once the set
 	// NativeHistogramMaxBucketNumber is exceeded, the following strategy is
-	// enacted: First, if the last reset (or the creation) of the histogram
-	// is at least NativeHistogramMinResetDuration ago, then the whole
-	// histogram is reset to its initial state (including regular
-	// buckets). If less time has passed, or if
-	// NativeHistogramMinResetDuration is zero, no reset is
-	// performed. Instead, the zero threshold is increased sufficiently to
-	// reduce the number of buckets to or below
-	// NativeHistogramMaxBucketNumber, but not to more than
-	// NativeHistogramMaxZeroThreshold. Thus, if
-	// NativeHistogramMaxZeroThreshold is already at or below the current
-	// zero threshold, nothing happens at this step. After that, if the
-	// number of buckets still exceeds NativeHistogramMaxBucketNumber, the
-	// resolution of the histogram is reduced by doubling the width of the
-	// sparse buckets (up to a growth factor between one bucket to the next
-	// of 2^(2^4) = 65536, see above).
+	// enacted:
+	//  - First, if the last reset (or the creation) of the histogram is at
+	//    least NativeHistogramMinResetDuration ago, then the whole
+	//    histogram is reset to its initial state (including regular
+	//    buckets).
+	//  - If less time has passed, or if NativeHistogramMinResetDuration is
+	//    zero, no reset is performed. Instead, the zero threshold is
+	//    increased sufficiently to reduce the number of buckets to or below
+	//    NativeHistogramMaxBucketNumber, but not to more than
+	//    NativeHistogramMaxZeroThreshold. Thus, if
+	//    NativeHistogramMaxZeroThreshold is already at or below the current
+	//    zero threshold, nothing happens at this step.
+	//  - After that, if the number of buckets still exceeds
+	//    NativeHistogramMaxBucketNumber, the resolution of the histogram is
+	//    reduced by doubling the width of the sparse buckets (up to a
+	//    growth factor between one bucket to the next of 2^(2^4) = 65536,
+	//    see above).
+	//  - Any increased zero threshold or reduced resolution is reset back
+	//    to their original values once NativeHistogramMinResetDuration has
+	//    passed (since the last reset or the creation of the histogram).
 	NativeHistogramMaxBucketNumber  uint32
 	NativeHistogramMinResetDuration time.Duration
 	NativeHistogramMaxZeroThreshold float64
+
+	// NativeHistogramMaxExemplars limits the number of exemplars
+	// that are kept in memory for each native histogram. If you leave it at
+	// zero, a default value of 10 is used. If no exemplars should be kept specifically
+	// for native histograms, set it to a negative value. (Scrapers can
+	// still use the exemplars exposed for classic buckets, which are managed
+	// independently.)
+	NativeHistogramMaxExemplars int
+	// NativeHistogramExemplarTTL is only checked once
+	// NativeHistogramMaxExemplars is exceeded. In that case, the
+	// oldest exemplar is removed if it is older than NativeHistogramExemplarTTL.
+	// Otherwise, the older exemplar in the pair of exemplars that are closest
+	// together (on an exponential scale) is removed.
+	// If NativeHistogramExemplarTTL is left at its zero value, a default value of
+	// 5m is used. To always delete the oldest exemplar, set it to a negative value.
+	NativeHistogramExemplarTTL time.Duration
+
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
+
+	// afterFunc is for testing purposes, by default it's time.AfterFunc.
+	afterFunc func(time.Duration, func()) *time.Timer
 }
 
 // HistogramVecOpts bundles the options to create a HistogramVec metric.
@@ -475,7 +509,7 @@ type HistogramVecOpts struct {
 	HistogramOpts
 
 	// VariableLabels are used to partition the metric vector by the given set
-	// of labels. Each label value will be constrained with the optional Contraint
+	// of labels. Each label value will be constrained with the optional Constraint
 	// function, if provided.
 	VariableLabels ConstrainableLabels
 }
@@ -499,12 +533,12 @@ func NewHistogram(opts HistogramOpts) Histogram {
 }
 
 func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogram {
-	if len(desc.variableLabels) != len(labelValues) {
-		panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.labelNames(), labelValues))
+	if len(desc.variableLabels.names) != len(labelValues) {
+		panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, labelValues))
 	}
 
-	for _, n := range desc.variableLabels {
-		if n.Name == bucketLabel {
+	for _, n := range desc.variableLabels.names {
+		if n == bucketLabel {
 			panic(errBucketLabelNotAllowed)
 		}
 	}
@@ -514,6 +548,13 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		}
 	}
 
+	if opts.now == nil {
+		opts.now = time.Now
+	}
+	if opts.afterFunc == nil {
+		opts.afterFunc = time.AfterFunc
+	}
+
 	h := &histogram{
 		desc:                            desc,
 		upperBounds:                     opts.Buckets,
@@ -521,8 +562,9 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		nativeHistogramMaxBuckets:       opts.NativeHistogramMaxBucketNumber,
 		nativeHistogramMaxZeroThreshold: opts.NativeHistogramMaxZeroThreshold,
 		nativeHistogramMinResetDuration: opts.NativeHistogramMinResetDuration,
-		lastResetTime:                   time.Now(),
-		now:                             time.Now,
+		lastResetTime:                   opts.now(),
+		now:                             opts.now,
+		afterFunc:                       opts.afterFunc,
 	}
 	if len(h.upperBounds) == 0 && opts.NativeHistogramBucketFactor <= 1 {
 		h.upperBounds = DefBuckets
@@ -537,6 +579,7 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 			h.nativeHistogramZeroThreshold = DefNativeHistogramZeroThreshold
 		} // Leave h.nativeHistogramZeroThreshold at 0 otherwise.
 		h.nativeHistogramSchema = pickSchema(opts.NativeHistogramBucketFactor)
+		h.nativeExemplars = makeNativeExemplars(opts.NativeHistogramExemplarTTL, opts.NativeHistogramMaxExemplars)
 	}
 	for i, upperBound := range h.upperBounds {
 		if i < len(h.upperBounds)-1 {
@@ -639,8 +682,8 @@ func (hc *histogramCounts) observe(v float64, bucket int, doSparse bool) {
 			if frac == 0.5 {
 				key--
 			}
-			div := 1 << -schema
-			key = (key + div - 1) / div
+			offset := (1 << -schema) - 1
+			key = (key + offset) >> -schema
 		}
 		if isInf {
 			key++
@@ -701,9 +744,19 @@ type histogram struct {
 	nativeHistogramMaxZeroThreshold float64
 	nativeHistogramMaxBuckets       uint32
 	nativeHistogramMinResetDuration time.Duration
-	lastResetTime                   time.Time // Protected by mtx.
+	// lastResetTime is protected by mtx. It is also used as created timestamp.
+	lastResetTime time.Time
+	// resetScheduled is protected by mtx. It is true if a reset is
+	// scheduled for a later time (when nativeHistogramMinResetDuration has
+	// passed).
+	resetScheduled  bool
+	nativeExemplars nativeExemplars
 
-	now func() time.Time // To mock out time.Now() for testing.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
+
+	// afterFunc is for testing purposes, by default it's time.AfterFunc.
+	afterFunc func(time.Duration, func()) *time.Timer
 }
 
 func (h *histogram) Desc() *Desc {
@@ -714,6 +767,9 @@ func (h *histogram) Observe(v float64) {
 	h.observe(v, h.findBucket(v))
 }
 
+// ObserveWithExemplar should not be called in a high-frequency setting
+// for a native histogram with configured exemplars. For this case,
+// the implementation isn't lock-free and might suffer from lock contention.
 func (h *histogram) ObserveWithExemplar(v float64, e Labels) {
 	i := h.findBucket(v)
 	h.observe(v, i)
@@ -742,9 +798,10 @@ func (h *histogram) Write(out *dto.Metric) error {
 	waitForCooldown(count, coldCounts)
 
 	his := &dto.Histogram{
-		Bucket:      make([]*dto.Bucket, len(h.upperBounds)),
-		SampleCount: proto.Uint64(count),
-		SampleSum:   proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		Bucket:           make([]*dto.Bucket, len(h.upperBounds)),
+		SampleCount:      proto.Uint64(count),
+		SampleSum:        proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		CreatedTimestamp: timestamppb.New(h.lastResetTime),
 	}
 	out.Histogram = his
 	out.Label = h.labelPairs
@@ -782,6 +839,23 @@ func (h *histogram) Write(out *dto.Metric) error {
 		his.ZeroCount = proto.Uint64(zeroBucket)
 		his.NegativeSpan, his.NegativeDelta = makeBuckets(&coldCounts.nativeHistogramBucketsNegative)
 		his.PositiveSpan, his.PositiveDelta = makeBuckets(&coldCounts.nativeHistogramBucketsPositive)
+
+		// Add a no-op span to a histogram without observations and with
+		// a zero threshold of zero. Otherwise, a native histogram would
+		// look like a classic histogram to scrapers.
+		if *his.ZeroThreshold == 0 && *his.ZeroCount == 0 && len(his.PositiveSpan) == 0 && len(his.NegativeSpan) == 0 {
+			his.PositiveSpan = []*dto.BucketSpan{{
+				Offset: proto.Int32(0),
+				Length: proto.Uint32(0),
+			}}
+		}
+
+		if h.nativeExemplars.isEnabled() {
+			h.nativeExemplars.Lock()
+			his.Exemplars = append(his.Exemplars, h.nativeExemplars.exemplars...)
+			h.nativeExemplars.Unlock()
+		}
+
 	}
 	addAndResetCounts(hotCounts, coldCounts)
 	return nil
@@ -790,15 +864,35 @@ func (h *histogram) Write(out *dto.Metric) error {
 // 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
+	n := len(h.upperBounds)
+	if n == 0 {
+		return 0
+	}
+
+	// Early exit: if v is less than or equal to the first upper bound, return 0
+	if v <= h.upperBounds[0] {
+		return 0
+	}
+
+	// Early exit: if v is greater than the last upper bound, return len(h.upperBounds)
+	if v > h.upperBounds[n-1] {
+		return n
+	}
+
+	// For small arrays, use simple linear search
+	// "magic number" 35 is result of tests on couple different (AWS and baremetal) servers
+	// see more details here: https://github.com/prometheus/client_golang/pull/1662
+	if n < 35 {
+		for i, bound := range h.upperBounds {
+			if v <= bound {
+				return i
+			}
+		}
+		// If v is greater than all upper bounds, return len(h.upperBounds)
+		return n
+	}
+
+	// For larger arrays, use stdlib's binary search
 	return sort.SearchFloat64s(h.upperBounds, v)
 }
 
@@ -817,7 +911,7 @@ func (h *histogram) observe(v float64, bucket int) {
 	}
 }
 
-// limitSparsebuckets applies a strategy to limit the number of populated sparse
+// limitBuckets applies a strategy to limit the number of populated sparse
 // buckets. It's generally best effort, and there are situations where the
 // number can go higher (if even the lowest resolution isn't enough to reduce
 // the number sufficiently, or if the provided counts aren't fully updated yet
@@ -848,26 +942,39 @@ func (h *histogram) limitBuckets(counts *histogramCounts, value float64, bucket
 	if h.maybeReset(hotCounts, coldCounts, coldIdx, value, bucket) {
 		return
 	}
+	// One of the other strategies will happen. To undo what they will do as
+	// soon as enough time has passed to satisfy
+	// h.nativeHistogramMinResetDuration, schedule a reset at the right time
+	// if we haven't done so already.
+	if h.nativeHistogramMinResetDuration > 0 && !h.resetScheduled {
+		h.resetScheduled = true
+		h.afterFunc(h.nativeHistogramMinResetDuration-h.now().Sub(h.lastResetTime), h.reset)
+	}
+
 	if h.maybeWidenZeroBucket(hotCounts, coldCounts) {
 		return
 	}
 	h.doubleBucketWidth(hotCounts, coldCounts)
 }
 
-// maybeReset resests the whole histogram if at least h.nativeHistogramMinResetDuration
-// has been passed. It returns true if the histogram has been reset. The caller
-// must have locked h.mtx.
-func (h *histogram) maybeReset(hot, cold *histogramCounts, coldIdx uint64, value float64, bucket int) bool {
+// maybeReset resets the whole histogram if at least
+// h.nativeHistogramMinResetDuration has been passed. It returns true if the
+// histogram has been reset. The caller must have locked h.mtx.
+func (h *histogram) maybeReset(
+	hot, cold *histogramCounts, coldIdx uint64, value float64, bucket int,
+) bool {
 	// We are using the possibly mocked h.now() rather than
 	// time.Since(h.lastResetTime) to enable testing.
-	if h.nativeHistogramMinResetDuration == 0 || h.now().Sub(h.lastResetTime) < h.nativeHistogramMinResetDuration {
+	if h.nativeHistogramMinResetDuration == 0 || // No reset configured.
+		h.resetScheduled || // Do not interefere if a reset is already scheduled.
+		h.now().Sub(h.lastResetTime) < h.nativeHistogramMinResetDuration {
 		return false
 	}
 	// Completely reset coldCounts.
 	h.resetCounts(cold)
 	// Repeat the latest observation to not lose it completely.
 	cold.observe(value, bucket, true)
-	// Make coldCounts the new hot counts while ressetting countAndHotIdx.
+	// Make coldCounts the new hot counts while resetting countAndHotIdx.
 	n := atomic.SwapUint64(&h.countAndHotIdx, (coldIdx<<63)+1)
 	count := n & ((1 << 63) - 1)
 	waitForCooldown(count, hot)
@@ -877,6 +984,29 @@ func (h *histogram) maybeReset(hot, cold *histogramCounts, coldIdx uint64, value
 	return true
 }
 
+// reset resets the whole histogram. It locks h.mtx itself, i.e. it has to be
+// called without having locked h.mtx.
+func (h *histogram) reset() {
+	h.mtx.Lock()
+	defer h.mtx.Unlock()
+
+	n := atomic.LoadUint64(&h.countAndHotIdx)
+	hotIdx := n >> 63
+	coldIdx := (^n) >> 63
+	hot := h.counts[hotIdx]
+	cold := h.counts[coldIdx]
+	// Completely reset coldCounts.
+	h.resetCounts(cold)
+	// Make coldCounts the new hot counts while resetting countAndHotIdx.
+	n = atomic.SwapUint64(&h.countAndHotIdx, coldIdx<<63)
+	count := n & ((1 << 63) - 1)
+	waitForCooldown(count, hot)
+	// Finally, reset the formerly hot counts, too.
+	h.resetCounts(hot)
+	h.lastResetTime = h.now()
+	h.resetScheduled = false
+}
+
 // maybeWidenZeroBucket widens the zero bucket until it includes the existing
 // buckets closest to the zero bucket (which could be two, if an equidistant
 // negative and a positive bucket exists, but usually it's only one bucket to be
@@ -1016,8 +1146,10 @@ func (h *histogram) resetCounts(counts *histogramCounts) {
 	deleteSyncMap(&counts.nativeHistogramBucketsPositive)
 }
 
-// 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.
+// updateExemplar replaces the exemplar for the provided classic bucket.
+// With empty labels, it's a no-op. It panics if any of the labels is invalid.
+// If histogram is native, the exemplar will be cached into nativeExemplars,
+// which has a limit, and will remove one exemplar when limit is reached.
 func (h *histogram) updateExemplar(v float64, bucket int, l Labels) {
 	if l == nil {
 		return
@@ -1027,6 +1159,10 @@ func (h *histogram) updateExemplar(v float64, bucket int, l Labels) {
 		panic(err)
 	}
 	h.exemplars[bucket].Store(e)
+	doSparse := h.nativeHistogramSchema > math.MinInt32 && !math.IsNaN(v)
+	if doSparse {
+		h.nativeExemplars.addExemplar(e)
+	}
 }
 
 // HistogramVec is a Collector that bundles a set of Histograms that all share the
@@ -1176,6 +1312,7 @@ type constHistogram struct {
 	sum        float64
 	buckets    map[float64]uint64
 	labelPairs []*dto.LabelPair
+	createdTs  *timestamppb.Timestamp
 }
 
 func (h *constHistogram) Desc() *Desc {
@@ -1183,7 +1320,9 @@ func (h *constHistogram) Desc() *Desc {
 }
 
 func (h *constHistogram) Write(out *dto.Metric) error {
-	his := &dto.Histogram{}
+	his := &dto.Histogram{
+		CreatedTimestamp: h.createdTs,
+	}
 
 	buckets := make([]*dto.Bucket, 0, len(h.buckets))
 
@@ -1230,7 +1369,7 @@ func NewConstHistogram(
 	if desc.err != nil {
 		return nil, desc.err
 	}
-	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
 		return nil, err
 	}
 	return &constHistogram{
@@ -1258,6 +1397,48 @@ func MustNewConstHistogram(
 	return m
 }
 
+// NewConstHistogramWithCreatedTimestamp does the same thing as NewConstHistogram but sets the created timestamp.
+func NewConstHistogramWithCreatedTimestamp(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	ct time.Time,
+	labelValues ...string,
+) (Metric, error) {
+	if desc.err != nil {
+		return nil, desc.err
+	}
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
+		return nil, err
+	}
+	return &constHistogram{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		buckets:    buckets,
+		labelPairs: MakeLabelPairs(desc, labelValues),
+		createdTs:  timestamppb.New(ct),
+	}, nil
+}
+
+// MustNewConstHistogramWithCreatedTimestamp is a version of NewConstHistogramWithCreatedTimestamp that panics where
+// NewConstHistogramWithCreatedTimestamp would have returned an error.
+func MustNewConstHistogramWithCreatedTimestamp(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	ct time.Time,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstHistogramWithCreatedTimestamp(desc, count, sum, buckets, ct, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
 type buckSort []*dto.Bucket
 
 func (s buckSort) Len() int {
@@ -1285,9 +1466,9 @@ func pickSchema(bucketFactor float64) int32 {
 	floor := math.Floor(math.Log2(math.Log2(bucketFactor)))
 	switch {
 	case floor <= -8:
-		return 8
+		return nativeHistogramSchemaMaximum
 	case floor >= 4:
-		return -4
+		return nativeHistogramSchemaMinimum
 	default:
 		return -int32(floor)
 	}
@@ -1324,7 +1505,7 @@ func makeBuckets(buckets *sync.Map) ([]*dto.BucketSpan, []int64) {
 		// Multiple spans with only small gaps in between are probably
 		// encoded more efficiently as one larger span with a few empty
 		// buckets. Needs some research to find the sweet spot. For now,
-		// we assume that gaps of one ore two buckets should not create
+		// we assume that gaps of one or two buckets should not create
 		// a new span.
 		iDelta := int32(i - nextI)
 		if n == 0 || iDelta > 2 {
@@ -1497,3 +1678,379 @@ func addAndResetCounts(hot, cold *histogramCounts) {
 	atomic.AddUint64(&hot.nativeHistogramZeroBucket, atomic.LoadUint64(&cold.nativeHistogramZeroBucket))
 	atomic.StoreUint64(&cold.nativeHistogramZeroBucket, 0)
 }
+
+type nativeExemplars struct {
+	sync.Mutex
+
+	// Time-to-live for exemplars, it is set to -1 if exemplars are disabled, that is NativeHistogramMaxExemplars is below 0.
+	// The ttl is used on insertion to remove an exemplar that is older than ttl, if present.
+	ttl time.Duration
+
+	exemplars []*dto.Exemplar
+}
+
+func (n *nativeExemplars) isEnabled() bool {
+	return n.ttl != -1
+}
+
+func makeNativeExemplars(ttl time.Duration, maxCount int) nativeExemplars {
+	if ttl == 0 {
+		ttl = 5 * time.Minute
+	}
+
+	if maxCount == 0 {
+		maxCount = 10
+	}
+
+	if maxCount < 0 {
+		maxCount = 0
+		ttl = -1
+	}
+
+	return nativeExemplars{
+		ttl:       ttl,
+		exemplars: make([]*dto.Exemplar, 0, maxCount),
+	}
+}
+
+func (n *nativeExemplars) addExemplar(e *dto.Exemplar) {
+	if !n.isEnabled() {
+		return
+	}
+
+	n.Lock()
+	defer n.Unlock()
+
+	// When the number of exemplars has not yet exceeded or
+	// is equal to cap(n.exemplars), then
+	// insert the new exemplar directly.
+	if len(n.exemplars) < cap(n.exemplars) {
+		var nIdx int
+		for nIdx = 0; nIdx < len(n.exemplars); nIdx++ {
+			if *e.Value < *n.exemplars[nIdx].Value {
+				break
+			}
+		}
+		n.exemplars = append(n.exemplars[:nIdx], append([]*dto.Exemplar{e}, n.exemplars[nIdx:]...)...)
+		return
+	}
+
+	if len(n.exemplars) == 1 {
+		// When the number of exemplars is 1, then
+		// replace the existing exemplar with the new exemplar.
+		n.exemplars[0] = e
+		return
+	}
+	// From this point on, the number of exemplars is greater than 1.
+
+	// When the number of exemplars exceeds the limit, remove one exemplar.
+	var (
+		ot    = time.Time{} // Oldest timestamp seen. Initial value doesn't matter as we replace it due to otIdx == -1 in the loop.
+		otIdx = -1          // Index of the exemplar with the oldest timestamp.
+
+		md = -1.0 // Logarithm of the delta of the closest pair of exemplars.
+
+		// The insertion point of the new exemplar in the exemplars slice after insertion.
+		// This is calculated purely based on the order of the exemplars by value.
+		// nIdx == len(n.exemplars) means the new exemplar is to be inserted after the end.
+		nIdx = -1
+
+		// rIdx is ultimately the index for the exemplar that we are replacing with the new exemplar.
+		// The aim is to keep a good spread of exemplars by value and not let them bunch up too much.
+		// It is calculated in 3 steps:
+		//   1. First we set rIdx to the index of the older exemplar within the closest pair by value.
+		//      That is the following will be true (on log scale):
+		//      either the exemplar pair on index (rIdx-1, rIdx) or (rIdx, rIdx+1) will have
+		//      the closest values to each other from all pairs.
+		//      For example, suppose the values are distributed like this:
+		//        |-----------x-------------x----------------x----x-----|
+		//                                                   ^--rIdx as this is older.
+		//      Or like this:
+		//        |-----------x-------------x----------------x----x-----|
+		//                                                        ^--rIdx as this is older.
+		//   2. If there is an exemplar that expired, then we simple reset rIdx to that index.
+		//   3. We check if by inserting the new exemplar we would create a closer pair at
+		//      (nIdx-1, nIdx) or (nIdx, nIdx+1) and set rIdx to nIdx-1 or nIdx accordingly to
+		//      keep the spread of exemplars by value; otherwise we keep rIdx as it is.
+		rIdx = -1
+		cLog float64 // Logarithm of the current exemplar.
+		pLog float64 // Logarithm of the previous exemplar.
+	)
+
+	for i, exemplar := range n.exemplars {
+		// Find the exemplar with the oldest timestamp.
+		if otIdx == -1 || exemplar.Timestamp.AsTime().Before(ot) {
+			ot = exemplar.Timestamp.AsTime()
+			otIdx = i
+		}
+
+		// Find the index at which to insert new the exemplar.
+		if nIdx == -1 && *e.Value <= *exemplar.Value {
+			nIdx = i
+		}
+
+		// Find the two closest exemplars and pick the one the with older timestamp.
+		pLog = cLog
+		cLog = math.Log(exemplar.GetValue())
+		if i == 0 {
+			continue
+		}
+		diff := math.Abs(cLog - pLog)
+		if md == -1 || diff < md {
+			// The closest exemplar pair is at index: i-1, i.
+			// Choose the exemplar with the older timestamp for replacement.
+			md = diff
+			if n.exemplars[i].Timestamp.AsTime().Before(n.exemplars[i-1].Timestamp.AsTime()) {
+				rIdx = i
+			} else {
+				rIdx = i - 1
+			}
+		}
+
+	}
+
+	// If all existing exemplar are smaller than new exemplar,
+	// then the exemplar should be inserted at the end.
+	if nIdx == -1 {
+		nIdx = len(n.exemplars)
+	}
+	// Here, we have the following relationships:
+	// n.exemplars[nIdx-1].Value < e.Value (if nIdx > 0)
+	// e.Value <= n.exemplars[nIdx].Value (if nIdx < len(n.exemplars))
+
+	if otIdx != -1 && e.Timestamp.AsTime().Sub(ot) > n.ttl {
+		// If the oldest exemplar has expired, then replace it with the new exemplar.
+		rIdx = otIdx
+	} else {
+		// In the previous for loop, when calculating the closest pair of exemplars,
+		// we did not take into account the newly inserted exemplar.
+		// So we need to calculate with the newly inserted exemplar again.
+		elog := math.Log(e.GetValue())
+		if nIdx > 0 {
+			diff := math.Abs(elog - math.Log(n.exemplars[nIdx-1].GetValue()))
+			if diff < md {
+				// The value we are about to insert is closer to the previous exemplar at the insertion point than what we calculated before in rIdx.
+				//                                            v--rIdx
+				// |-----------x-n-----------x----------------x----x-----|
+				//     nIdx-1--^ ^--new exemplar value
+				// Do not make the spread worse, replace nIdx-1 and not rIdx.
+				md = diff
+				rIdx = nIdx - 1
+			}
+		}
+		if nIdx < len(n.exemplars) {
+			diff := math.Abs(math.Log(n.exemplars[nIdx].GetValue()) - elog)
+			if diff < md {
+				// The value we are about to insert is closer to the next exemplar at the insertion point than what we calculated before in rIdx.
+				//                                            v--rIdx
+				// |-----------x-----------n-x----------------x----x-----|
+				//     new exemplar value--^ ^--nIdx
+				// Do not make the spread worse, replace nIdx-1 and not rIdx.
+				rIdx = nIdx
+			}
+		}
+	}
+
+	// Adjust the slice according to rIdx and nIdx.
+	switch {
+	case rIdx == nIdx:
+		n.exemplars[nIdx] = e
+	case rIdx < nIdx:
+		n.exemplars = append(n.exemplars[:rIdx], append(n.exemplars[rIdx+1:nIdx], append([]*dto.Exemplar{e}, n.exemplars[nIdx:]...)...)...)
+	case rIdx > nIdx:
+		n.exemplars = append(n.exemplars[:nIdx], append([]*dto.Exemplar{e}, append(n.exemplars[nIdx:rIdx], n.exemplars[rIdx+1:]...)...)...)
+	}
+}
+
+type constNativeHistogram struct {
+	desc *Desc
+	dto.Histogram
+	labelPairs []*dto.LabelPair
+}
+
+func validateCount(sum float64, count uint64, negativeBuckets, positiveBuckets map[int]int64, zeroBucket uint64) error {
+	var bucketPopulationSum int64
+	for _, v := range positiveBuckets {
+		bucketPopulationSum += v
+	}
+	for _, v := range negativeBuckets {
+		bucketPopulationSum += v
+	}
+	bucketPopulationSum += int64(zeroBucket)
+
+	// If the sum of observations is NaN, the number of observations must be greater or equal to the sum of all bucket counts.
+	// Otherwise, the number of observations must be equal to the sum of all bucket counts .
+
+	if math.IsNaN(sum) && bucketPopulationSum > int64(count) ||
+		!math.IsNaN(sum) && bucketPopulationSum != int64(count) {
+		return errors.New("the sum of all bucket populations exceeds the count of observations")
+	}
+	return nil
+}
+
+// NewConstNativeHistogram returns a metric representing a Prometheus native histogram with
+// fixed values for the count, sum, and positive/negative/zero 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
+// OpenTelemetry Collectors, it is useful as a throw-away metric that is generated on the fly
+// to send it to Prometheus in the Collect method.
+//
+// zeroBucket counts all (positive and negative)
+// observations in the zero bucket (with an absolute value less or equal
+// the current threshold).
+// positiveBuckets and negativeBuckets are separate maps for negative and positive
+// observations. The map's value is an int64, counting observations in
+// that bucket. The map's key is the
+// index of the bucket according to the used
+// Schema. Index 0 is for an upper bound of 1 in positive buckets and for a lower bound of -1 in negative buckets.
+// NewConstNativeHistogram returns an error if
+//   - the length of labelValues is not consistent with the variable labels in Desc or if Desc is invalid.
+//   - the schema passed is not between 8 and -4
+//   - the sum of counts in all buckets including the zero bucket does not equal the count if sum is not NaN (or exceeds the count if sum is NaN)
+//
+// See https://opentelemetry.io/docs/specs/otel/compatibility/prometheus_and_openmetrics/#exponential-histograms for more details about the conversion from OTel to Prometheus.
+func NewConstNativeHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	positiveBuckets, negativeBuckets map[int]int64,
+	zeroBucket uint64,
+	schema int32,
+	zeroThreshold float64,
+	createdTimestamp time.Time,
+	labelValues ...string,
+) (Metric, error) {
+	if desc.err != nil {
+		return nil, desc.err
+	}
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
+		return nil, err
+	}
+	if schema > nativeHistogramSchemaMaximum || schema < nativeHistogramSchemaMinimum {
+		return nil, errors.New("invalid native histogram schema")
+	}
+	if err := validateCount(sum, count, negativeBuckets, positiveBuckets, zeroBucket); err != nil {
+		return nil, err
+	}
+
+	NegativeSpan, NegativeDelta := makeBucketsFromMap(negativeBuckets)
+	PositiveSpan, PositiveDelta := makeBucketsFromMap(positiveBuckets)
+	ret := &constNativeHistogram{
+		desc: desc,
+		Histogram: dto.Histogram{
+			CreatedTimestamp: timestamppb.New(createdTimestamp),
+			Schema:           &schema,
+			ZeroThreshold:    &zeroThreshold,
+			SampleCount:      &count,
+			SampleSum:        &sum,
+
+			NegativeSpan:  NegativeSpan,
+			NegativeDelta: NegativeDelta,
+
+			PositiveSpan:  PositiveSpan,
+			PositiveDelta: PositiveDelta,
+
+			ZeroCount: proto.Uint64(zeroBucket),
+		},
+		labelPairs: MakeLabelPairs(desc, labelValues),
+	}
+	if *ret.ZeroThreshold == 0 && *ret.ZeroCount == 0 && len(ret.PositiveSpan) == 0 && len(ret.NegativeSpan) == 0 {
+		ret.PositiveSpan = []*dto.BucketSpan{{
+			Offset: proto.Int32(0),
+			Length: proto.Uint32(0),
+		}}
+	}
+	return ret, nil
+}
+
+// MustNewConstNativeHistogram is a version of NewConstNativeHistogram that panics where
+// NewConstNativeHistogram would have returned an error.
+func MustNewConstNativeHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	positiveBuckets, negativeBuckets map[int]int64,
+	zeroBucket uint64,
+	nativeHistogramSchema int32,
+	nativeHistogramZeroThreshold float64,
+	createdTimestamp time.Time,
+	labelValues ...string,
+) Metric {
+	nativehistogram, err := NewConstNativeHistogram(desc,
+		count,
+		sum,
+		positiveBuckets,
+		negativeBuckets,
+		zeroBucket,
+		nativeHistogramSchema,
+		nativeHistogramZeroThreshold,
+		createdTimestamp,
+		labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return nativehistogram
+}
+
+func (h *constNativeHistogram) Desc() *Desc {
+	return h.desc
+}
+
+func (h *constNativeHistogram) Write(out *dto.Metric) error {
+	out.Histogram = &h.Histogram
+	out.Label = h.labelPairs
+	return nil
+}
+
+func makeBucketsFromMap(buckets map[int]int64) ([]*dto.BucketSpan, []int64) {
+	if len(buckets) == 0 {
+		return nil, nil
+	}
+	var ii []int
+	for k := range buckets {
+		ii = append(ii, k)
+	}
+	sort.Ints(ii)
+
+	var (
+		spans     []*dto.BucketSpan
+		deltas    []int64
+		prevCount int64
+		nextI     int
+	)
+
+	appendDelta := func(count int64) {
+		*spans[len(spans)-1].Length++
+		deltas = append(deltas, count-prevCount)
+		prevCount = count
+	}
+
+	for n, i := range ii {
+		count := buckets[i]
+		// Multiple spans with only small gaps in between are probably
+		// encoded more efficiently as one larger span with a few empty
+		// buckets. Needs some research to find the sweet spot. For now,
+		// we assume that gaps of one or two buckets should not create
+		// a new span.
+		iDelta := int32(i - nextI)
+		if n == 0 || iDelta > 2 {
+			// We have to create a new span, either because we are
+			// at the very beginning, or because we have found a gap
+			// of more than two buckets.
+			spans = append(spans, &dto.BucketSpan{
+				Offset: proto.Int32(iDelta),
+				Length: proto.Uint32(0),
+			})
+		} else {
+			// We have found a small gap (or no gap at all).
+			// Insert empty buckets as needed.
+			for j := int32(0); j < iDelta; j++ {
+				appendDelta(0)
+			}
+		}
+		appendDelta(count)
+		nextI = i + 1
+	}
+	return spans, deltas
+}

vendor/github.com/prometheus/client_golang/prometheus/internal/difflib.go

@@ -14,7 +14,7 @@
 // It provides tools to compare sequences of strings and generate textual diffs.
 //
 // Maintaining `GetUnifiedDiffString` here because original repository
-// (https://github.com/pmezard/go-difflib) is no loger maintained.
+// (https://github.com/pmezard/go-difflib) is no longer maintained.
 package internal
 
 import (
@@ -22,17 +22,18 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 )
 
-func min(a, b int) int {
+func minInt(a, b int) int {
 	if a < b {
 		return a
 	}
 	return b
 }
 
-func max(a, b int) int {
+func maxInt(a, b int) int {
 	if a > b {
 		return a
 	}
@@ -427,12 +428,12 @@ func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode {
 	if codes[0].Tag == 'e' {
 		c := codes[0]
 		i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
-		codes[0] = OpCode{c.Tag, max(i1, i2-n), i2, max(j1, j2-n), j2}
+		codes[0] = OpCode{c.Tag, maxInt(i1, i2-n), i2, maxInt(j1, j2-n), j2}
 	}
 	if codes[len(codes)-1].Tag == 'e' {
 		c := codes[len(codes)-1]
 		i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
-		codes[len(codes)-1] = OpCode{c.Tag, i1, min(i2, i1+n), j1, min(j2, j1+n)}
+		codes[len(codes)-1] = OpCode{c.Tag, i1, minInt(i2, i1+n), j1, minInt(j2, j1+n)}
 	}
 	nn := n + n
 	groups := [][]OpCode{}
@@ -443,16 +444,16 @@ func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode {
 		// there is a large range with no changes.
 		if c.Tag == 'e' && i2-i1 > nn {
 			group = append(group, OpCode{
-				c.Tag, i1, min(i2, i1+n),
-				j1, min(j2, j1+n),
+				c.Tag, i1, minInt(i2, i1+n),
+				j1, minInt(j2, j1+n),
 			})
 			groups = append(groups, group)
 			group = []OpCode{}
-			i1, j1 = max(i1, i2-n), max(j1, j2-n)
+			i1, j1 = maxInt(i1, i2-n), maxInt(j1, j2-n)
 		}
 		group = append(group, OpCode{c.Tag, i1, i2, j1, j2})
 	}
-	if len(group) > 0 && !(len(group) == 1 && group[0].Tag == 'e') {
+	if len(group) > 0 && (len(group) != 1 || group[0].Tag != 'e') {
 		groups = append(groups, group)
 	}
 	return groups
@@ -515,7 +516,7 @@ func (m *SequenceMatcher) QuickRatio() float64 {
 // is faster to compute than either .Ratio() or .QuickRatio().
 func (m *SequenceMatcher) RealQuickRatio() float64 {
 	la, lb := len(m.a), len(m.b)
-	return calculateRatio(min(la, lb), la+lb)
+	return calculateRatio(minInt(la, lb), la+lb)
 }
 
 // Convert range to the "ed" format
@@ -524,7 +525,7 @@ func formatRangeUnified(start, stop int) string {
 	beginning := start + 1 // lines start numbering with one
 	length := stop - start
 	if length == 1 {
-		return fmt.Sprintf("%d", beginning)
+		return strconv.Itoa(beginning)
 	}
 	if length == 0 {
 		beginning-- // empty ranges begin at line just before the range
@@ -567,7 +568,7 @@ func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error {
 	buf := bufio.NewWriter(writer)
 	defer buf.Flush()
 	wf := func(format string, args ...interface{}) error {
-		_, err := buf.WriteString(fmt.Sprintf(format, args...))
+		_, err := fmt.Fprintf(buf, format, args...)
 		return err
 	}
 	ws := func(s string) error {

vendor/github.com/prometheus/client_golang/prometheus/internal/go_collector_options.go

@@ -30,3 +30,5 @@ type GoCollectorOptions struct {
 	RuntimeMetricSumForHist    map[string]string
 	RuntimeMetricRules         []GoCollectorRule
 }
+
+var GoCollectorDefaultRuntimeMetrics = regexp.MustCompile(`/gc/gogc:percent|/gc/gomemlimit:bytes|/sched/gomaxprocs:threads`)

vendor/github.com/prometheus/client_golang/prometheus/internal/go_runtime_metrics.go

@@ -66,7 +66,8 @@ func RuntimeMetricsToProm(d *metrics.Description) (string, string, string, bool)
 		name += "_total"
 	}
 
-	valid := model.IsValidMetricName(model.LabelValue(namespace + "_" + subsystem + "_" + name))
+	// Our current conversion moves to legacy naming, so use legacy validation.
+	valid := model.LegacyValidation.IsValidMetricName(namespace + "_" + subsystem + "_" + name)
 	switch d.Kind {
 	case metrics.KindUint64:
 	case metrics.KindFloat64:

vendor/github.com/prometheus/client_golang/prometheus/labels.go

@@ -32,19 +32,15 @@ import (
 // create a Desc.
 type Labels map[string]string
 
+// LabelConstraint normalizes label values.
+type LabelConstraint func(string) string
+
 // ConstrainedLabels represents a label name and its constrain function
 // to normalize label values. This type is commonly used when constructing
 // metric vector Collectors.
 type ConstrainedLabel struct {
 	Name       string
-	Constraint func(string) string
-}
-
-func (cl ConstrainedLabel) Constrain(v string) string {
-	if cl.Constraint == nil {
-		return v
-	}
-	return cl.Constraint(v)
+	Constraint LabelConstraint
 }
 
 // ConstrainableLabels is an interface that allows creating of labels that can
@@ -58,7 +54,7 @@ func (cl ConstrainedLabel) Constrain(v string) string {
 //	  },
 //	})
 type ConstrainableLabels interface {
-	constrainedLabels() ConstrainedLabels
+	compile() *compiledLabels
 	labelNames() []string
 }
 
@@ -67,8 +63,20 @@ type ConstrainableLabels interface {
 // metric vector Collectors.
 type ConstrainedLabels []ConstrainedLabel
 
-func (cls ConstrainedLabels) constrainedLabels() ConstrainedLabels {
-	return cls
+func (cls ConstrainedLabels) compile() *compiledLabels {
+	compiled := &compiledLabels{
+		names:            make([]string, len(cls)),
+		labelConstraints: map[string]LabelConstraint{},
+	}
+
+	for i, label := range cls {
+		compiled.names[i] = label.Name
+		if label.Constraint != nil {
+			compiled.labelConstraints[label.Name] = label.Constraint
+		}
+	}
+
+	return compiled
 }
 
 func (cls ConstrainedLabels) labelNames() []string {
@@ -92,18 +100,36 @@ func (cls ConstrainedLabels) labelNames() []string {
 //	}
 type UnconstrainedLabels []string
 
-func (uls UnconstrainedLabels) constrainedLabels() ConstrainedLabels {
-	constrainedLabels := make([]ConstrainedLabel, len(uls))
-	for i, l := range uls {
-		constrainedLabels[i] = ConstrainedLabel{Name: l}
+func (uls UnconstrainedLabels) compile() *compiledLabels {
+	return &compiledLabels{
+		names: uls,
 	}
-	return constrainedLabels
 }
 
 func (uls UnconstrainedLabels) labelNames() []string {
 	return uls
 }
 
+type compiledLabels struct {
+	names            []string
+	labelConstraints map[string]LabelConstraint
+}
+
+func (cls *compiledLabels) compile() *compiledLabels {
+	return cls
+}
+
+func (cls *compiledLabels) labelNames() []string {
+	return cls.names
+}
+
+func (cls *compiledLabels) constrain(labelName, value string) string {
+	if fn, ok := cls.labelConstraints[labelName]; ok && fn != nil {
+		return fn(value)
+	}
+	return value
+}
+
 // reservedLabelPrefix is a prefix which is not legal in user-supplied
 // label names.
 const reservedLabelPrefix = "__"
@@ -139,6 +165,8 @@ func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
 
 func validateLabelValues(vals []string, expectedNumberOfValues int) error {
 	if len(vals) != expectedNumberOfValues {
+		// The call below makes vals escape, copy them to avoid that.
+		vals := append([]string(nil), vals...)
 		return fmt.Errorf(
 			"%w: expected %d label values but got %d in %#v",
 			errInconsistentCardinality, expectedNumberOfValues,
@@ -156,5 +184,6 @@ func validateLabelValues(vals []string, expectedNumberOfValues int) error {
 }
 
 func checkLabelName(l string) bool {
-	return model.LabelName(l).IsValid() && !strings.HasPrefix(l, reservedLabelPrefix)
+	//nolint:staticcheck // TODO: Don't use deprecated model.NameValidationScheme.
+	return model.NameValidationScheme.IsValidLabelName(l) && !strings.HasPrefix(l, reservedLabelPrefix)
 }

vendor/github.com/prometheus/client_golang/prometheus/metric.go

@@ -92,6 +92,9 @@ type Opts struct {
 	// machine_role metric). See also
 	// https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels-not-static-scraped-labels
 	ConstLabels Labels
+
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 // BuildFQName joins the given three name components by "_". Empty name
@@ -105,15 +108,23 @@ func BuildFQName(namespace, subsystem, name string) string {
 	if name == "" {
 		return ""
 	}
-	switch {
-	case namespace != "" && subsystem != "":
-		return strings.Join([]string{namespace, subsystem, name}, "_")
-	case namespace != "":
-		return strings.Join([]string{namespace, name}, "_")
-	case subsystem != "":
-		return strings.Join([]string{subsystem, name}, "_")
+
+	sb := strings.Builder{}
+	sb.Grow(len(namespace) + len(subsystem) + len(name) + 2)
+
+	if namespace != "" {
+		sb.WriteString(namespace)
+		sb.WriteString("_")
 	}
-	return name
+
+	if subsystem != "" {
+		sb.WriteString(subsystem)
+		sb.WriteString("_")
+	}
+
+	sb.WriteString(name)
+
+	return sb.String()
 }
 
 type invalidMetric struct {
@@ -175,21 +186,31 @@ func (m *withExemplarsMetric) Write(pb *dto.Metric) error {
 	case pb.Counter != nil:
 		pb.Counter.Exemplar = m.exemplars[len(m.exemplars)-1]
 	case pb.Histogram != nil:
+		h := pb.Histogram
 		for _, e := range m.exemplars {
-			// pb.Histogram.Bucket are sorted by UpperBound.
-			i := sort.Search(len(pb.Histogram.Bucket), func(i int) bool {
-				return pb.Histogram.Bucket[i].GetUpperBound() >= e.GetValue()
+			if (h.GetZeroThreshold() != 0 || h.GetZeroCount() != 0 ||
+				len(h.PositiveSpan) != 0 || len(h.NegativeSpan) != 0) &&
+				e.GetTimestamp() != nil {
+				h.Exemplars = append(h.Exemplars, e)
+				if len(h.Bucket) == 0 {
+					// Don't proceed to classic buckets if there are none.
+					continue
+				}
+			}
+			// h.Bucket are sorted by UpperBound.
+			i := sort.Search(len(h.Bucket), func(i int) bool {
+				return h.Bucket[i].GetUpperBound() >= e.GetValue()
 			})
-			if i < len(pb.Histogram.Bucket) {
-				pb.Histogram.Bucket[i].Exemplar = e
+			if i < len(h.Bucket) {
+				h.Bucket[i].Exemplar = e
 			} else {
 				// The +Inf bucket should be explicitly added if there is an exemplar for it, similar to non-const histogram logic in https://github.com/prometheus/client_golang/blob/main/prometheus/histogram.go#L357-L365.
 				b := &dto.Bucket{
-					CumulativeCount: proto.Uint64(pb.Histogram.GetSampleCount()),
+					CumulativeCount: proto.Uint64(h.GetSampleCount()),
 					UpperBound:      proto.Float64(math.Inf(1)),
 					Exemplar:        e,
 				}
-				pb.Histogram.Bucket = append(pb.Histogram.Bucket, b)
+				h.Bucket = append(h.Bucket, b)
 			}
 		}
 	default:
@@ -216,6 +237,7 @@ type Exemplar struct {
 // Only last applicable exemplar is injected from the list.
 // For example for Counter it means last exemplar is injected.
 // For Histogram, it means last applicable exemplar for each bucket is injected.
+// For a Native Histogram, all valid exemplars are injected.
 //
 // NewMetricWithExemplars works best with MustNewConstMetric and
 // MustNewConstHistogram, see example.
@@ -231,7 +253,7 @@ func NewMetricWithExemplars(m Metric, exemplars ...Exemplar) (Metric, error) {
 	)
 	for i, e := range exemplars {
 		ts := e.Timestamp
-		if ts == (time.Time{}) {
+		if ts.IsZero() {
 			ts = now
 		}
 		exs[i], err = newExemplar(e.Value, ts, e.Labels)

vendor/github.com/prometheus/client_golang/prometheus/process_collector.go

@@ -22,14 +22,16 @@ import (
 )
 
 type processCollector struct {
-	collectFn       func(chan<- Metric)
-	pidFn           func() (int, error)
-	reportErrors    bool
-	cpuTotal        *Desc
-	openFDs, maxFDs *Desc
-	vsize, maxVsize *Desc
-	rss             *Desc
-	startTime       *Desc
+	collectFn         func(chan<- Metric)
+	describeFn        func(chan<- *Desc)
+	pidFn             func() (int, error)
+	reportErrors      bool
+	cpuTotal          *Desc
+	openFDs, maxFDs   *Desc
+	vsize, maxVsize   *Desc
+	rss               *Desc
+	startTime         *Desc
+	inBytes, outBytes *Desc
 }
 
 // ProcessCollectorOpts defines the behavior of a process metrics collector
@@ -100,6 +102,16 @@ func NewProcessCollector(opts ProcessCollectorOpts) Collector {
 			"Start time of the process since unix epoch in seconds.",
 			nil, nil,
 		),
+		inBytes: NewDesc(
+			ns+"process_network_receive_bytes_total",
+			"Number of bytes received by the process over the network.",
+			nil, nil,
+		),
+		outBytes: NewDesc(
+			ns+"process_network_transmit_bytes_total",
+			"Number of bytes sent by the process over the network.",
+			nil, nil,
+		),
 	}
 
 	if opts.PidFn == nil {
@@ -111,24 +123,23 @@ func NewProcessCollector(opts ProcessCollectorOpts) Collector {
 	// Set up process metric collection if supported by the runtime.
 	if canCollectProcess() {
 		c.collectFn = c.processCollect
+		c.describeFn = c.describe
 	} else {
-		c.collectFn = func(ch chan<- Metric) {
-			c.reportError(ch, nil, errors.New("process metrics not supported on this platform"))
-		}
+		c.collectFn = c.errorCollectFn
+		c.describeFn = c.errorDescribeFn
 	}
 
 	return c
 }
 
-// Describe returns all descriptions of the collector.
-func (c *processCollector) Describe(ch chan<- *Desc) {
-	ch <- c.cpuTotal
-	ch <- c.openFDs
-	ch <- c.maxFDs
-	ch <- c.vsize
-	ch <- c.maxVsize
-	ch <- c.rss
-	ch <- c.startTime
+func (c *processCollector) errorCollectFn(ch chan<- Metric) {
+	c.reportError(ch, nil, errors.New("process metrics not supported on this platform"))
+}
+
+func (c *processCollector) errorDescribeFn(ch chan<- *Desc) {
+	if c.reportErrors {
+		ch <- NewInvalidDesc(errors.New("process metrics not supported on this platform"))
+	}
 }
 
 // Collect returns the current state of all metrics of the collector.
@@ -136,6 +147,11 @@ func (c *processCollector) Collect(ch chan<- Metric) {
 	c.collectFn(ch)
 }
 
+// Describe returns all descriptions of the collector.
+func (c *processCollector) Describe(ch chan<- *Desc) {
+	c.describeFn(ch)
+}
+
 func (c *processCollector) reportError(ch chan<- Metric, desc *Desc, err error) {
 	if !c.reportErrors {
 		return

vendor/github.com/prometheus/client_golang/prometheus/process_collector_darwin.go

@@ -0,0 +1,130 @@
+// Copyright 2024 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.
+
+//go:build darwin && !ios
+
+package prometheus
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// errNotImplemented is returned by stub functions that replace cgo functions, when cgo
+// isn't available.
+var errNotImplemented = errors.New("not implemented")
+
+type memoryInfo struct {
+	vsize uint64 // Virtual memory size in bytes
+	rss   uint64 // Resident memory size in bytes
+}
+
+func canCollectProcess() bool {
+	return true
+}
+
+func getSoftLimit(which int) (uint64, error) {
+	rlimit := syscall.Rlimit{}
+
+	if err := syscall.Getrlimit(which, &rlimit); err != nil {
+		return 0, err
+	}
+
+	return rlimit.Cur, nil
+}
+
+func getOpenFileCount() (float64, error) {
+	// Alternately, the undocumented proc_pidinfo(PROC_PIDLISTFDS) can be used to
+	// return a list of open fds, but that requires a way to call C APIs.  The
+	// benefits, however, include fewer system calls and not failing when at the
+	// open file soft limit.
+
+	if dir, err := os.Open("/dev/fd"); err != nil {
+		return 0.0, err
+	} else {
+		defer dir.Close()
+
+		// Avoid ReadDir(), as it calls stat(2) on each descriptor.  Not only is
+		// that info not used, but KQUEUE descriptors fail stat(2), which causes
+		// the whole method to fail.
+		if names, err := dir.Readdirnames(0); err != nil {
+			return 0.0, err
+		} else {
+			// Subtract 1 to ignore the open /dev/fd descriptor above.
+			return float64(len(names) - 1), nil
+		}
+	}
+}
+
+func (c *processCollector) processCollect(ch chan<- Metric) {
+	if procs, err := unix.SysctlKinfoProcSlice("kern.proc.pid", os.Getpid()); err == nil {
+		if len(procs) == 1 {
+			startTime := float64(procs[0].Proc.P_starttime.Nano() / 1e9)
+			ch <- MustNewConstMetric(c.startTime, GaugeValue, startTime)
+		} else {
+			err = fmt.Errorf("sysctl() returned %d proc structs (expected 1)", len(procs))
+			c.reportError(ch, c.startTime, err)
+		}
+	} else {
+		c.reportError(ch, c.startTime, err)
+	}
+
+	// The proc structure returned by kern.proc.pid above has an Rusage member,
+	// but it is not filled in, so it needs to be fetched by getrusage(2).  For
+	// that call, the UTime, STime, and Maxrss members are filled out, but not
+	// Ixrss, Idrss, or Isrss for the memory usage.  Memory stats will require
+	// access to the C API to call task_info(TASK_BASIC_INFO).
+	rusage := unix.Rusage{}
+
+	if err := unix.Getrusage(syscall.RUSAGE_SELF, &rusage); err == nil {
+		cpuTime := time.Duration(rusage.Stime.Nano() + rusage.Utime.Nano()).Seconds()
+		ch <- MustNewConstMetric(c.cpuTotal, CounterValue, cpuTime)
+	} else {
+		c.reportError(ch, c.cpuTotal, err)
+	}
+
+	if memInfo, err := getMemory(); err == nil {
+		ch <- MustNewConstMetric(c.rss, GaugeValue, float64(memInfo.rss))
+		ch <- MustNewConstMetric(c.vsize, GaugeValue, float64(memInfo.vsize))
+	} else if !errors.Is(err, errNotImplemented) {
+		// Don't report an error when support is not compiled in.
+		c.reportError(ch, c.rss, err)
+		c.reportError(ch, c.vsize, err)
+	}
+
+	if fds, err := getOpenFileCount(); err == nil {
+		ch <- MustNewConstMetric(c.openFDs, GaugeValue, fds)
+	} else {
+		c.reportError(ch, c.openFDs, err)
+	}
+
+	if openFiles, err := getSoftLimit(syscall.RLIMIT_NOFILE); err == nil {
+		ch <- MustNewConstMetric(c.maxFDs, GaugeValue, float64(openFiles))
+	} else {
+		c.reportError(ch, c.maxFDs, err)
+	}
+
+	if addressSpace, err := getSoftLimit(syscall.RLIMIT_AS); err == nil {
+		ch <- MustNewConstMetric(c.maxVsize, GaugeValue, float64(addressSpace))
+	} else {
+		c.reportError(ch, c.maxVsize, err)
+	}
+
+	// TODO: socket(PF_SYSTEM) to fetch "com.apple.network.statistics" might
+	//  be able to get the per-process network send/receive counts.
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector_mem_cgo_darwin.c

@@ -0,0 +1,84 @@
+// Copyright 2024 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.
+
+//go:build darwin && !ios && cgo
+
+#include <mach/mach_init.h>
+#include <mach/task.h>
+#include <mach/mach_vm.h>
+
+// The compiler warns that mach/shared_memory_server.h is deprecated, and to use
+// mach/shared_region.h instead.  But that doesn't define
+// SHARED_DATA_REGION_SIZE or SHARED_TEXT_REGION_SIZE, so redefine them here and
+// avoid a warning message when running tests.
+#define GLOBAL_SHARED_TEXT_SEGMENT      0x90000000U
+#define SHARED_DATA_REGION_SIZE         0x10000000
+#define SHARED_TEXT_REGION_SIZE         0x10000000
+
+
+int get_memory_info(unsigned long long *rss, unsigned long long *vsize)
+{
+    // This is lightly adapted from how ps(1) obtains its memory info.
+    // https://github.com/apple-oss-distributions/adv_cmds/blob/8744084ea0ff41ca4bb96b0f9c22407d0e48e9b7/ps/tasks.c#L109
+
+    kern_return_t               error;
+    task_t                      task = MACH_PORT_NULL;
+    mach_task_basic_info_data_t info;
+    mach_msg_type_number_t      info_count = MACH_TASK_BASIC_INFO_COUNT;
+
+    error = task_info(
+                mach_task_self(),
+                MACH_TASK_BASIC_INFO,
+                (task_info_t) &info,
+                &info_count );
+
+    if( error != KERN_SUCCESS )
+    {
+        return error;
+    }
+
+    *rss   = info.resident_size;
+    *vsize = info.virtual_size;
+
+    {
+        vm_region_basic_info_data_64_t    b_info;
+        mach_vm_address_t                 address = GLOBAL_SHARED_TEXT_SEGMENT;
+        mach_vm_size_t                    size;
+        mach_port_t                       object_name;
+
+        /*
+         * try to determine if this task has the split libraries
+         * mapped in... if so, adjust its virtual size down by
+         * the 2 segments that are used for split libraries
+         */
+        info_count = VM_REGION_BASIC_INFO_COUNT_64;
+
+        error = mach_vm_region(
+                    mach_task_self(),
+                    &address,
+                    &size,
+                    VM_REGION_BASIC_INFO_64,
+                    (vm_region_info_t) &b_info,
+                    &info_count,
+                    &object_name);
+
+        if (error == KERN_SUCCESS) {
+            if (b_info.reserved && size == (SHARED_TEXT_REGION_SIZE) &&
+                *vsize > (SHARED_TEXT_REGION_SIZE + SHARED_DATA_REGION_SIZE)) {
+                    *vsize -= (SHARED_TEXT_REGION_SIZE + SHARED_DATA_REGION_SIZE);
+            }
+        }
+    }
+
+    return 0;
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector_mem_cgo_darwin.go

@@ -0,0 +1,51 @@
+// Copyright 2024 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.
+
+//go:build darwin && !ios && cgo
+
+package prometheus
+
+/*
+int get_memory_info(unsigned long long *rss, unsigned long long *vs);
+*/
+import "C"
+import "fmt"
+
+func getMemory() (*memoryInfo, error) {
+	var rss, vsize C.ulonglong
+
+	if err := C.get_memory_info(&rss, &vsize); err != 0 {
+		return nil, fmt.Errorf("task_info() failed with 0x%x", int(err))
+	}
+
+	return &memoryInfo{vsize: uint64(vsize), rss: uint64(rss)}, nil
+}
+
+// describe returns all descriptions of the collector for Darwin.
+// Ensure that this list of descriptors is kept in sync with the metrics collected
+// in the processCollect method. Any changes to the metrics in processCollect
+// (such as adding or removing metrics) should be reflected in this list of descriptors.
+func (c *processCollector) describe(ch chan<- *Desc) {
+	ch <- c.cpuTotal
+	ch <- c.openFDs
+	ch <- c.maxFDs
+	ch <- c.maxVsize
+	ch <- c.startTime
+	ch <- c.rss
+	ch <- c.vsize
+
+	/* the process could be collected but not implemented yet
+	ch <- c.inBytes
+	ch <- c.outBytes
+	*/
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector_mem_nocgo_darwin.go

@@ -0,0 +1,39 @@
+// Copyright 2024 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.
+
+//go:build darwin && !ios && !cgo
+
+package prometheus
+
+func getMemory() (*memoryInfo, error) {
+	return nil, errNotImplemented
+}
+
+// describe returns all descriptions of the collector for Darwin.
+// Ensure that this list of descriptors is kept in sync with the metrics collected
+// in the processCollect method. Any changes to the metrics in processCollect
+// (such as adding or removing metrics) should be reflected in this list of descriptors.
+func (c *processCollector) describe(ch chan<- *Desc) {
+	ch <- c.cpuTotal
+	ch <- c.openFDs
+	ch <- c.maxFDs
+	ch <- c.maxVsize
+	ch <- c.startTime
+
+	/* the process could be collected but not implemented yet
+	ch <- c.rss
+	ch <- c.vsize
+	ch <- c.inBytes
+	ch <- c.outBytes
+	*/
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector_not_supported.go

@@ -1,4 +1,4 @@
-// Copyright 2019 The Prometheus Authors
+// Copyright 2023 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
@@ -11,8 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build js
-// +build js
+//go:build wasip1 || js || ios
+// +build wasip1 js ios
 
 package prometheus
 
@@ -21,6 +21,13 @@ func canCollectProcess() bool {
 }
 
 func (c *processCollector) processCollect(ch chan<- Metric) {
-	// noop on this platform
-	return
+	c.errorCollectFn(ch)
+}
+
+// describe returns all descriptions of the collector for wasip1 and js.
+// Ensure that this list of descriptors is kept in sync with the metrics collected
+// in the processCollect method. Any changes to the metrics in processCollect
+// (such as adding or removing metrics) should be reflected in this list of descriptors.
+func (c *processCollector) describe(ch chan<- *Desc) {
+	c.errorDescribeFn(ch)
 }

vendor/github.com/prometheus/client_golang/prometheus/process_collector_procfsenabled.go

@@ -11,8 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !windows && !js
-// +build !windows,!js
+//go:build !windows && !js && !wasip1 && !darwin
+// +build !windows,!js,!wasip1,!darwin
 
 package prometheus
 
@@ -63,4 +63,34 @@ func (c *processCollector) processCollect(ch chan<- Metric) {
 	} else {
 		c.reportError(ch, nil, err)
 	}
+
+	if netstat, err := p.Netstat(); err == nil {
+		var inOctets, outOctets float64
+		if netstat.InOctets != nil {
+			inOctets = *netstat.InOctets
+		}
+		if netstat.OutOctets != nil {
+			outOctets = *netstat.OutOctets
+		}
+		ch <- MustNewConstMetric(c.inBytes, CounterValue, inOctets)
+		ch <- MustNewConstMetric(c.outBytes, CounterValue, outOctets)
+	} else {
+		c.reportError(ch, nil, err)
+	}
+}
+
+// describe returns all descriptions of the collector for others than windows, js, wasip1 and darwin.
+// Ensure that this list of descriptors is kept in sync with the metrics collected
+// in the processCollect method. Any changes to the metrics in processCollect
+// (such as adding or removing metrics) should be reflected in this list of descriptors.
+func (c *processCollector) describe(ch chan<- *Desc) {
+	ch <- c.cpuTotal
+	ch <- c.openFDs
+	ch <- c.maxFDs
+	ch <- c.vsize
+	ch <- c.maxVsize
+	ch <- c.rss
+	ch <- c.startTime
+	ch <- c.inBytes
+	ch <- c.outBytes
 }

vendor/github.com/prometheus/client_golang/prometheus/process_collector_windows.go

@@ -79,14 +79,10 @@ func getProcessHandleCount(handle windows.Handle) (uint32, error) {
 }
 
 func (c *processCollector) processCollect(ch chan<- Metric) {
-	h, err := windows.GetCurrentProcess()
-	if err != nil {
-		c.reportError(ch, nil, err)
-		return
-	}
+	h := windows.CurrentProcess()
 
 	var startTime, exitTime, kernelTime, userTime windows.Filetime
-	err = windows.GetProcessTimes(h, &startTime, &exitTime, &kernelTime, &userTime)
+	err := windows.GetProcessTimes(h, &startTime, &exitTime, &kernelTime, &userTime)
 	if err != nil {
 		c.reportError(ch, nil, err)
 		return
@@ -111,6 +107,19 @@ func (c *processCollector) processCollect(ch chan<- Metric) {
 	ch <- MustNewConstMetric(c.maxFDs, GaugeValue, float64(16*1024*1024)) // Windows has a hard-coded max limit, not per-process.
 }
 
+// describe returns all descriptions of the collector for windows.
+// Ensure that this list of descriptors is kept in sync with the metrics collected
+// in the processCollect method. Any changes to the metrics in processCollect
+// (such as adding or removing metrics) should be reflected in this list of descriptors.
+func (c *processCollector) describe(ch chan<- *Desc) {
+	ch <- c.cpuTotal
+	ch <- c.openFDs
+	ch <- c.maxFDs
+	ch <- c.vsize
+	ch <- c.rss
+	ch <- c.startTime
+}
+
 func fileTimeToSeconds(ft windows.Filetime) float64 {
 	return float64(uint64(ft.HighDateTime)<<32+uint64(ft.LowDateTime)) / 1e7
 }

vendor/github.com/prometheus/client_golang/prometheus/registry.go

@@ -314,16 +314,17 @@ func (r *Registry) Register(c Collector) error {
 			if dimHash != desc.dimHash {
 				return fmt.Errorf("a previously registered descriptor with the same fully-qualified name as %s has different label names or a different help string", desc)
 			}
-		} else {
-			// ...then check the new descriptors already seen.
-			if dimHash, exists := newDimHashesByName[desc.fqName]; exists {
-				if dimHash != desc.dimHash {
-					return fmt.Errorf("descriptors reported by collector have inconsistent label names or help strings for the same fully-qualified name, offender is %s", desc)
-				}
-			} else {
-				newDimHashesByName[desc.fqName] = desc.dimHash
-			}
+			continue
 		}
+
+		// ...then check the new descriptors already seen.
+		if dimHash, exists := newDimHashesByName[desc.fqName]; exists {
+			if dimHash != desc.dimHash {
+				return fmt.Errorf("descriptors reported by collector have inconsistent label names or help strings for the same fully-qualified name, offender is %s", desc)
+			}
+			continue
+		}
+		newDimHashesByName[desc.fqName] = desc.dimHash
 	}
 	// A Collector yielding no Desc at all is considered unchecked.
 	if len(newDescIDs) == 0 {
@@ -548,7 +549,7 @@ func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
 			goroutineBudget--
 			runtime.Gosched()
 		}
-		// Once both checkedMetricChan and uncheckdMetricChan are closed
+		// Once both checkedMetricChan and uncheckedMetricChan are closed
 		// and drained, the contraption above will nil out cmc and umc,
 		// and then we can leave the collect loop here.
 		if cmc == nil && umc == nil {
@@ -963,9 +964,9 @@ func checkDescConsistency(
 	// Is the desc consistent with the content of the metric?
 	lpsFromDesc := make([]*dto.LabelPair, len(desc.constLabelPairs), len(dtoMetric.Label))
 	copy(lpsFromDesc, desc.constLabelPairs)
-	for _, l := range desc.variableLabels {
+	for _, l := range desc.variableLabels.names {
 		lpsFromDesc = append(lpsFromDesc, &dto.LabelPair{
-			Name: proto.String(l.Name),
+			Name: proto.String(l),
 		})
 	}
 	if len(lpsFromDesc) != len(dtoMetric.Label) {

vendor/github.com/prometheus/client_golang/prometheus/summary.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/beorn7/perks/quantile"
 	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // quantileLabel is used for the label that defines the quantile in a
@@ -145,6 +146,9 @@ type SummaryOpts struct {
 	// is the internal buffer size of the underlying package
 	// "github.com/bmizerany/perks/quantile").
 	BufCap uint32
+
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 // SummaryVecOpts bundles the options to create a SummaryVec metric.
@@ -154,7 +158,7 @@ type SummaryVecOpts struct {
 	SummaryOpts
 
 	// VariableLabels are used to partition the metric vector by the given set
-	// of labels. Each label value will be constrained with the optional Contraint
+	// of labels. Each label value will be constrained with the optional Constraint
 	// function, if provided.
 	VariableLabels ConstrainableLabels
 }
@@ -188,12 +192,12 @@ func NewSummary(opts SummaryOpts) Summary {
 }
 
 func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
-	if len(desc.variableLabels) != len(labelValues) {
-		panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.labelNames(), labelValues))
+	if len(desc.variableLabels.names) != len(labelValues) {
+		panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, labelValues))
 	}
 
-	for _, n := range desc.variableLabels {
-		if n.Name == quantileLabel {
+	for _, n := range desc.variableLabels.names {
+		if n == quantileLabel {
 			panic(errQuantileLabelNotAllowed)
 		}
 	}
@@ -222,6 +226,9 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 		opts.BufCap = DefBufCap
 	}
 
+	if opts.now == nil {
+		opts.now = time.Now
+	}
 	if len(opts.Objectives) == 0 {
 		// Use the lock-free implementation of a Summary without objectives.
 		s := &noObjectivesSummary{
@@ -230,11 +237,13 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 			counts:     [2]*summaryCounts{{}, {}},
 		}
 		s.init(s) // Init self-collection.
+		s.createdTs = timestamppb.New(opts.now())
 		return s
 	}
 
 	s := &summary{
 		desc: desc,
+		now:  opts.now,
 
 		objectives:       opts.Objectives,
 		sortedObjectives: make([]float64, 0, len(opts.Objectives)),
@@ -245,7 +254,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 		coldBuf:        make([]float64, 0, opts.BufCap),
 		streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets),
 	}
-	s.headStreamExpTime = time.Now().Add(s.streamDuration)
+	s.headStreamExpTime = opts.now().Add(s.streamDuration)
 	s.hotBufExpTime = s.headStreamExpTime
 
 	for i := uint32(0); i < opts.AgeBuckets; i++ {
@@ -259,6 +268,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 	sort.Float64s(s.sortedObjectives)
 
 	s.init(s) // Init self-collection.
+	s.createdTs = timestamppb.New(opts.now())
 	return s
 }
 
@@ -271,6 +281,8 @@ type summary struct {
 
 	desc *Desc
 
+	now func() time.Time
+
 	objectives       map[float64]float64
 	sortedObjectives []float64
 
@@ -286,6 +298,8 @@ type summary struct {
 	headStream                       *quantile.Stream
 	headStreamIdx                    int
 	headStreamExpTime, hotBufExpTime time.Time
+
+	createdTs *timestamppb.Timestamp
 }
 
 func (s *summary) Desc() *Desc {
@@ -296,7 +310,7 @@ func (s *summary) Observe(v float64) {
 	s.bufMtx.Lock()
 	defer s.bufMtx.Unlock()
 
-	now := time.Now()
+	now := s.now()
 	if now.After(s.hotBufExpTime) {
 		s.asyncFlush(now)
 	}
@@ -307,13 +321,15 @@ func (s *summary) Observe(v float64) {
 }
 
 func (s *summary) Write(out *dto.Metric) error {
-	sum := &dto.Summary{}
+	sum := &dto.Summary{
+		CreatedTimestamp: s.createdTs,
+	}
 	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.swapBufs(s.now())
 	s.bufMtx.Unlock()
 
 	s.flushColdBuf()
@@ -440,6 +456,8 @@ type noObjectivesSummary struct {
 	counts [2]*summaryCounts
 
 	labelPairs []*dto.LabelPair
+
+	createdTs *timestamppb.Timestamp
 }
 
 func (s *noObjectivesSummary) Desc() *Desc {
@@ -490,8 +508,9 @@ func (s *noObjectivesSummary) Write(out *dto.Metric) error {
 	}
 
 	sum := &dto.Summary{
-		SampleCount: proto.Uint64(count),
-		SampleSum:   proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		SampleCount:      proto.Uint64(count),
+		SampleSum:        proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
+		CreatedTimestamp: s.createdTs,
 	}
 
 	out.Summary = sum
@@ -681,6 +700,7 @@ type constSummary struct {
 	sum        float64
 	quantiles  map[float64]float64
 	labelPairs []*dto.LabelPair
+	createdTs  *timestamppb.Timestamp
 }
 
 func (s *constSummary) Desc() *Desc {
@@ -688,7 +708,9 @@ func (s *constSummary) Desc() *Desc {
 }
 
 func (s *constSummary) Write(out *dto.Metric) error {
-	sum := &dto.Summary{}
+	sum := &dto.Summary{
+		CreatedTimestamp: s.createdTs,
+	}
 	qs := make([]*dto.Quantile, 0, len(s.quantiles))
 
 	sum.SampleCount = proto.Uint64(s.count)
@@ -737,7 +759,7 @@ func NewConstSummary(
 	if desc.err != nil {
 		return nil, desc.err
 	}
-	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
 		return nil, err
 	}
 	return &constSummary{
@@ -764,3 +786,45 @@ func MustNewConstSummary(
 	}
 	return m
 }
+
+// NewConstSummaryWithCreatedTimestamp does the same thing as NewConstSummary but sets the created timestamp.
+func NewConstSummaryWithCreatedTimestamp(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	ct time.Time,
+	labelValues ...string,
+) (Metric, error) {
+	if desc.err != nil {
+		return nil, desc.err
+	}
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
+		return nil, err
+	}
+	return &constSummary{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		quantiles:  quantiles,
+		labelPairs: MakeLabelPairs(desc, labelValues),
+		createdTs:  timestamppb.New(ct),
+	}, nil
+}
+
+// MustNewConstSummaryWithCreatedTimestamp is a version of NewConstSummaryWithCreatedTimestamp that panics where
+// NewConstSummaryWithCreatedTimestamp would have returned an error.
+func MustNewConstSummaryWithCreatedTimestamp(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	ct time.Time,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstSummaryWithCreatedTimestamp(desc, count, sum, quantiles, ct, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}

vendor/github.com/prometheus/client_golang/prometheus/value.go

@@ -14,6 +14,7 @@
 package prometheus
 
 import (
+	"errors"
 	"fmt"
 	"sort"
 	"time"
@@ -91,7 +92,7 @@ func (v *valueFunc) Desc() *Desc {
 }
 
 func (v *valueFunc) Write(out *dto.Metric) error {
-	return populateMetric(v.valType, v.function(), v.labelPairs, nil, out)
+	return populateMetric(v.valType, v.function(), v.labelPairs, nil, out, nil)
 }
 
 // NewConstMetric returns a metric with one fixed value that cannot be
@@ -105,12 +106,12 @@ func NewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues
 	if desc.err != nil {
 		return nil, desc.err
 	}
-	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
 		return nil, err
 	}
 
 	metric := &dto.Metric{}
-	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric); err != nil {
+	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric, nil); err != nil {
 		return nil, err
 	}
 
@@ -130,6 +131,43 @@ func MustNewConstMetric(desc *Desc, valueType ValueType, value float64, labelVal
 	return m
 }
 
+// NewConstMetricWithCreatedTimestamp does the same thing as NewConstMetric, but generates Counters
+// with created timestamp set and returns an error for other metric types.
+func NewConstMetricWithCreatedTimestamp(desc *Desc, valueType ValueType, value float64, ct time.Time, labelValues ...string) (Metric, error) {
+	if desc.err != nil {
+		return nil, desc.err
+	}
+	if err := validateLabelValues(labelValues, len(desc.variableLabels.names)); err != nil {
+		return nil, err
+	}
+	switch valueType {
+	case CounterValue:
+		break
+	default:
+		return nil, errors.New("created timestamps are only supported for counters")
+	}
+
+	metric := &dto.Metric{}
+	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric, timestamppb.New(ct)); err != nil {
+		return nil, err
+	}
+
+	return &constMetric{
+		desc:   desc,
+		metric: metric,
+	}, nil
+}
+
+// MustNewConstMetricWithCreatedTimestamp is a version of NewConstMetricWithCreatedTimestamp that panics where
+// NewConstMetricWithCreatedTimestamp would have returned an error.
+func MustNewConstMetricWithCreatedTimestamp(desc *Desc, valueType ValueType, value float64, ct time.Time, labelValues ...string) Metric {
+	m, err := NewConstMetricWithCreatedTimestamp(desc, valueType, value, ct, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
 type constMetric struct {
 	desc   *Desc
 	metric *dto.Metric
@@ -153,11 +191,12 @@ func populateMetric(
 	labelPairs []*dto.LabelPair,
 	e *dto.Exemplar,
 	m *dto.Metric,
+	ct *timestamppb.Timestamp,
 ) error {
 	m.Label = labelPairs
 	switch t {
 	case CounterValue:
-		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e}
+		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e, CreatedTimestamp: ct}
 	case GaugeValue:
 		m.Gauge = &dto.Gauge{Value: proto.Float64(v)}
 	case UntypedValue:
@@ -176,19 +215,19 @@ func populateMetric(
 // This function is only needed for custom Metric implementations. See MetricVec
 // example.
 func MakeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
-	totalLen := len(desc.variableLabels) + len(desc.constLabelPairs)
+	totalLen := len(desc.variableLabels.names) + len(desc.constLabelPairs)
 	if totalLen == 0 {
 		// Super fast path.
 		return nil
 	}
-	if len(desc.variableLabels) == 0 {
+	if len(desc.variableLabels.names) == 0 {
 		// Moderately fast path.
 		return desc.constLabelPairs
 	}
 	labelPairs := make([]*dto.LabelPair, 0, totalLen)
-	for i, l := range desc.variableLabels {
+	for i, l := range desc.variableLabels.names {
 		labelPairs = append(labelPairs, &dto.LabelPair{
-			Name:  proto.String(l.Name),
+			Name:  proto.String(l),
 			Value: proto.String(labelValues[i]),
 		})
 	}

vendor/github.com/prometheus/client_golang/prometheus/vec.go

@@ -73,12 +73,13 @@ func NewMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *MetricVec {
 // See also the CounterVec example.
 func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
 	lvs = constrainLabelValues(m.desc, lvs, m.curry)
+
 	h, err := m.hashLabelValues(lvs)
 	if err != nil {
 		return false
 	}
 
-	return m.metricMap.deleteByHashWithLabelValues(h, lvs, m.curry)
+	return m.deleteByHashWithLabelValues(h, lvs, m.curry)
 }
 
 // Delete deletes the metric where the variable labels are the same as those
@@ -92,13 +93,15 @@ func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
 // This method is used for the same purpose as DeleteLabelValues(...string). See
 // there for pros and cons of the two methods.
 func (m *MetricVec) Delete(labels Labels) bool {
-	labels = constrainLabels(m.desc, labels)
+	labels, closer := constrainLabels(m.desc, labels)
+	defer closer()
+
 	h, err := m.hashLabels(labels)
 	if err != nil {
 		return false
 	}
 
-	return m.metricMap.deleteByHashWithLabels(h, labels, m.curry)
+	return m.deleteByHashWithLabels(h, labels, m.curry)
 }
 
 // DeletePartialMatch deletes all metrics where the variable labels contain all of those
@@ -108,8 +111,10 @@ func (m *MetricVec) Delete(labels Labels) bool {
 // Note that curried labels will never be matched if deleting from the curried vector.
 // To match curried labels with DeletePartialMatch, it must be called on the base vector.
 func (m *MetricVec) DeletePartialMatch(labels Labels) int {
-	labels = constrainLabels(m.desc, labels)
-	return m.metricMap.deleteByLabels(labels, m.curry)
+	labels, closer := constrainLabels(m.desc, labels)
+	defer closer()
+
+	return m.deleteByLabels(labels, m.curry)
 }
 
 // Without explicit forwarding of Describe, Collect, Reset, those methods won't
@@ -147,11 +152,11 @@ func (m *MetricVec) CurryWith(labels Labels) (*MetricVec, error) {
 		oldCurry = m.curry
 		iCurry   int
 	)
-	for i, label := range m.desc.variableLabels {
-		val, ok := labels[label.Name]
+	for i, labelName := range m.desc.variableLabels.names {
+		val, ok := labels[labelName]
 		if iCurry < len(oldCurry) && oldCurry[iCurry].index == i {
 			if ok {
-				return nil, fmt.Errorf("label name %q is already curried", label.Name)
+				return nil, fmt.Errorf("label name %q is already curried", labelName)
 			}
 			newCurry = append(newCurry, oldCurry[iCurry])
 			iCurry++
@@ -159,7 +164,10 @@ func (m *MetricVec) CurryWith(labels Labels) (*MetricVec, error) {
 			if !ok {
 				continue // Label stays uncurried.
 			}
-			newCurry = append(newCurry, curriedLabelValue{i, label.Constrain(val)})
+			newCurry = append(newCurry, curriedLabelValue{
+				i,
+				m.desc.variableLabels.constrain(labelName, val),
+			})
 		}
 	}
 	if l := len(oldCurry) + len(labels) - len(newCurry); l > 0 {
@@ -208,7 +216,7 @@ func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
 		return nil, err
 	}
 
-	return m.metricMap.getOrCreateMetricWithLabelValues(h, lvs, m.curry), nil
+	return m.getOrCreateMetricWithLabelValues(h, lvs, m.curry), nil
 }
 
 // GetMetricWith returns the Metric for the given Labels map (the label names
@@ -228,17 +236,19 @@ func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
 // around MetricVec, implementing a vector for a specific Metric implementation,
 // for example GaugeVec.
 func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
-	labels = constrainLabels(m.desc, labels)
+	labels, closer := constrainLabels(m.desc, labels)
+	defer closer()
+
 	h, err := m.hashLabels(labels)
 	if err != nil {
 		return nil, err
 	}
 
-	return m.metricMap.getOrCreateMetricWithLabels(h, labels, m.curry), nil
+	return m.getOrCreateMetricWithLabels(h, labels, m.curry), nil
 }
 
 func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
-	if err := validateLabelValues(vals, len(m.desc.variableLabels)-len(m.curry)); err != nil {
+	if err := validateLabelValues(vals, len(m.desc.variableLabels.names)-len(m.curry)); err != nil {
 		return 0, err
 	}
 
@@ -247,7 +257,7 @@ func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
 		curry         = m.curry
 		iVals, iCurry int
 	)
-	for i := 0; i < len(m.desc.variableLabels); i++ {
+	for i := 0; i < len(m.desc.variableLabels.names); i++ {
 		if iCurry < len(curry) && curry[iCurry].index == i {
 			h = m.hashAdd(h, curry[iCurry].value)
 			iCurry++
@@ -261,7 +271,7 @@ func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
 }
 
 func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
-	if err := validateValuesInLabels(labels, len(m.desc.variableLabels)-len(m.curry)); err != nil {
+	if err := validateValuesInLabels(labels, len(m.desc.variableLabels.names)-len(m.curry)); err != nil {
 		return 0, err
 	}
 
@@ -270,17 +280,17 @@ func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
 		curry  = m.curry
 		iCurry int
 	)
-	for i, label := range m.desc.variableLabels {
-		val, ok := labels[label.Name]
+	for i, labelName := range m.desc.variableLabels.names {
+		val, ok := labels[labelName]
 		if iCurry < len(curry) && curry[iCurry].index == i {
 			if ok {
-				return 0, fmt.Errorf("label name %q is already curried", label.Name)
+				return 0, fmt.Errorf("label name %q is already curried", labelName)
 			}
 			h = m.hashAdd(h, curry[iCurry].value)
 			iCurry++
 		} else {
 			if !ok {
-				return 0, fmt.Errorf("label name %q missing in label map", label.Name)
+				return 0, fmt.Errorf("label name %q missing in label map", labelName)
 			}
 			h = m.hashAdd(h, val)
 		}
@@ -458,7 +468,7 @@ func valueMatchesVariableOrCurriedValue(targetValue string, index int, values []
 func matchPartialLabels(desc *Desc, values []string, labels Labels, curry []curriedLabelValue) bool {
 	for l, v := range labels {
 		// Check if the target label exists in our metrics and get the index.
-		varLabelIndex, validLabel := indexOf(l, desc.variableLabels.labelNames())
+		varLabelIndex, validLabel := indexOf(l, desc.variableLabels.names)
 		if validLabel {
 			// Check the value of that label against the target value.
 			// We don't consider curried values in partial matches.
@@ -497,7 +507,7 @@ func (m *metricMap) getOrCreateMetricWithLabelValues(
 	return metric
 }
 
-// getOrCreateMetricWithLabelValues retrieves the metric by hash and label value
+// getOrCreateMetricWithLabels retrieves the metric by hash and label value
 // or creates it and returns the new one.
 //
 // This function holds the mutex.
@@ -602,7 +612,7 @@ func matchLabels(desc *Desc, values []string, labels Labels, curry []curriedLabe
 		return false
 	}
 	iCurry := 0
-	for i, k := range desc.variableLabels {
+	for i, k := range desc.variableLabels.names {
 		if iCurry < len(curry) && curry[iCurry].index == i {
 			if values[i] != curry[iCurry].value {
 				return false
@@ -610,7 +620,7 @@ func matchLabels(desc *Desc, values []string, labels Labels, curry []curriedLabe
 			iCurry++
 			continue
 		}
-		if values[i] != labels[k.Name] {
+		if values[i] != labels[k] {
 			return false
 		}
 	}
@@ -620,13 +630,13 @@ func matchLabels(desc *Desc, values []string, labels Labels, curry []curriedLabe
 func extractLabelValues(desc *Desc, labels Labels, curry []curriedLabelValue) []string {
 	labelValues := make([]string, len(labels)+len(curry))
 	iCurry := 0
-	for i, k := range desc.variableLabels {
+	for i, k := range desc.variableLabels.names {
 		if iCurry < len(curry) && curry[iCurry].index == i {
 			labelValues[i] = curry[iCurry].value
 			iCurry++
 			continue
 		}
-		labelValues[i] = labels[k.Name]
+		labelValues[i] = labels[k]
 	}
 	return labelValues
 }
@@ -646,19 +656,37 @@ func inlineLabelValues(lvs []string, curry []curriedLabelValue) []string {
 	return labelValues
 }
 
-func constrainLabels(desc *Desc, labels Labels) Labels {
-	constrainedValues := make(Labels, len(labels))
-	for l, v := range labels {
-		if i, ok := indexOf(l, desc.variableLabels.labelNames()); ok {
-			constrainedValues[l] = desc.variableLabels[i].Constrain(v)
-			continue
-		}
-		constrainedValues[l] = v
+var labelsPool = &sync.Pool{
+	New: func() interface{} {
+		return make(Labels)
+	},
+}
+
+func constrainLabels(desc *Desc, labels Labels) (Labels, func()) {
+	if len(desc.variableLabels.labelConstraints) == 0 {
+		// Fast path when there's no constraints
+		return labels, func() {}
+	}
+
+	constrainedLabels := labelsPool.Get().(Labels)
+	for l, v := range labels {
+		constrainedLabels[l] = desc.variableLabels.constrain(l, v)
+	}
+
+	return constrainedLabels, func() {
+		for k := range constrainedLabels {
+			delete(constrainedLabels, k)
+		}
+		labelsPool.Put(constrainedLabels)
 	}
-	return constrainedValues
 }
 
 func constrainLabelValues(desc *Desc, lvs []string, curry []curriedLabelValue) []string {
+	if len(desc.variableLabels.labelConstraints) == 0 {
+		// Fast path when there's no constraints
+		return lvs
+	}
+
 	constrainedValues := make([]string, len(lvs))
 	var iCurry, iLVs int
 	for i := 0; i < len(lvs)+len(curry); i++ {
@@ -667,8 +695,11 @@ func constrainLabelValues(desc *Desc, lvs []string, curry []curriedLabelValue) [
 			continue
 		}
 
-		if i < len(desc.variableLabels) {
-			constrainedValues[iLVs] = desc.variableLabels[i].Constrain(lvs[iLVs])
+		if i < len(desc.variableLabels.names) {
+			constrainedValues[iLVs] = desc.variableLabels.constrain(
+				desc.variableLabels.names[i],
+				lvs[iLVs],
+			)
 		} else {
 			constrainedValues[iLVs] = lvs[iLVs]
 		}

vendor/github.com/prometheus/client_golang/prometheus/wrap.go

@@ -63,7 +63,7 @@ func WrapRegistererWith(labels Labels, reg Registerer) Registerer {
 // metric names that are standardized across applications, as that would break
 // horizontal monitoring, for example the metrics provided by the Go collector
 // (see NewGoCollector) and the process collector (see NewProcessCollector). (In
-// fact, those metrics are already prefixed with “go_” or “process_”,
+// fact, those metrics are already prefixed with "go_" or "process_",
 // respectively.)
 //
 // Conflicts between Collectors registered through the original Registerer with
@@ -78,6 +78,40 @@ func WrapRegistererWithPrefix(prefix string, reg Registerer) Registerer {
 	}
 }
 
+// WrapCollectorWith returns a Collector wrapping the provided Collector. The
+// wrapped Collector will add the provided Labels to all Metrics it collects (as
+// ConstLabels). The Metrics collected by the unmodified Collector must not
+// duplicate any of those labels.
+//
+// WrapCollectorWith can be useful to work with multiple instances of a third
+// party library that does not expose enough flexibility on the lifecycle of its
+// registered metrics.
+// For example, let's say you have a foo.New(reg Registerer) constructor that
+// registers metrics but never unregisters them, and you want to create multiple
+// instances of foo.Foo with different labels.
+// The way to achieve that, is to create a new Registry, pass it to foo.New,
+// then use WrapCollectorWith to wrap that Registry with the desired labels and
+// register that as a collector in your main Registry.
+// Then you can un-register the wrapped collector effectively un-registering the
+// metrics registered by foo.New.
+func WrapCollectorWith(labels Labels, c Collector) Collector {
+	return &wrappingCollector{
+		wrappedCollector: c,
+		labels:           labels,
+	}
+}
+
+// WrapCollectorWithPrefix returns a Collector wrapping the provided Collector. The
+// wrapped Collector will add the provided prefix to the name of all Metrics it collects.
+//
+// See the documentation of WrapCollectorWith for more details on the use case.
+func WrapCollectorWithPrefix(prefix string, c Collector) Collector {
+	return &wrappingCollector{
+		wrappedCollector: c,
+		prefix:           prefix,
+	}
+}
+
 type wrappingRegisterer struct {
 	wrappedRegisterer Registerer
 	prefix            string