feat(vec): add Reset() to all {Counter,Gauge,Histogram,Summary}Vec — prom-compat

metric.go

@@ -105,24 +105,28 @@ type Factory interface {
 type CounterVec interface {
 	With(Labels) Counter
 	WithLabelValues(...string) Counter
+	Reset()
 }
 
 // GaugeVec is a labeled gauge collection.
 type GaugeVec interface {
 	With(Labels) Gauge
 	WithLabelValues(...string) Gauge
+	Reset()
 }
 
 // HistogramVec is a labeled histogram collection.
 type HistogramVec interface {
 	With(Labels) Histogram
 	WithLabelValues(...string) Histogram
+	Reset()
 }
 
 // SummaryVec is a labeled summary collection.
 type SummaryVec interface {
 	With(Labels) Summary
 	WithLabelValues(...string) Summary
+	Reset()
 }
 
 // MetricsHTTPHandler handles HTTP requests for metrics.

metrics_impl.go

@@ -665,6 +665,19 @@ func (hpr *registry) RegisterLabeledSummary(name string, labels Labels, summary
 	hpr.summaries[name][key] = &labeledSummary{labels: cloneLabels(labels), summary: summary}
 }
 
+// deregisterLabeled drops all label-permutation children for the named
+// metric across counter/gauge/histogram/summary registries. Called by
+// {Counter,Gauge,Histogram,Summary}Vec.Reset() to mirror prometheus
+// vec semantics.
+func (hpr *registry) deregisterLabeled(name string) {
+	hpr.mu.Lock()
+	defer hpr.mu.Unlock()
+	delete(hpr.counters, name)
+	delete(hpr.gauges, name)
+	delete(hpr.histograms, name)
+	delete(hpr.summaries, name)
+}
+
 // NewCounter creates and registers a counter.
 func (hpr *registry) NewCounter(name, help string) Counter {
 	counter := newCounter(name, help)
@@ -862,6 +875,15 @@ func (v *counterVec) getOrCreate(labels Labels) Counter {
 	return counter
 }
 
+// Reset drops every label-permutation child from this vec. Mirrors
+// prometheus/client_golang.CounterVec.Reset semantics.
+func (v *counterVec) Reset() {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	v.registry.deregisterLabeled(v.name)
+	v.counters = make(map[string]Counter)
+}
+
 // gaugeVec is a labeled gauge collection.
 type gaugeVec struct {
 	registry   *registry
@@ -904,6 +926,14 @@ func (v *gaugeVec) getOrCreate(labels Labels) Gauge {
 	return gauge
 }
 
+// Reset drops every label-permutation child from this vec.
+func (v *gaugeVec) Reset() {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	v.registry.deregisterLabeled(v.name)
+	v.gauges = make(map[string]Gauge)
+}
+
 // histogramVec is a labeled histogram collection.
 type histogramVec struct {
 	registry   *registry
@@ -948,6 +978,14 @@ func (v *histogramVec) getOrCreate(labels Labels) Histogram {
 	return histogram
 }
 
+// Reset drops every label-permutation child from this vec.
+func (v *histogramVec) Reset() {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	v.registry.deregisterLabeled(v.name)
+	v.histograms = make(map[string]Histogram)
+}
+
 // summaryVec is a labeled summary collection.
 type summaryVec struct {
 	registry   *registry
@@ -996,6 +1034,14 @@ func (v *summaryVec) getOrCreate(labels Labels) Summary {
 	return summary
 }
 
+// Reset drops every label-permutation child from this vec.
+func (v *summaryVec) Reset() {
+	v.mu.Lock()
+	defer v.mu.Unlock()
+	v.registry.deregisterLabeled(v.name)
+	v.summaries = make(map[string]Summary)
+}
+
 func labelsFromValues(labelNames []string, values []string) Labels {
 	labels := make(Labels, len(labelNames))
 	for i, name := range labelNames {

noop.go

@@ -35,24 +35,28 @@ type noopCounterVec struct{}
 
 func (n *noopCounterVec) With(Labels) Counter               { return &noopCounter{} }
 func (n *noopCounterVec) WithLabelValues(...string) Counter { return &noopCounter{} }
+func (n *noopCounterVec) Reset()                            {}
 
 // noopGaugeVec is a gauge vector that does nothing.
 type noopGaugeVec struct{}
 
 func (n *noopGaugeVec) With(Labels) Gauge               { return &noopGauge{} }
 func (n *noopGaugeVec) WithLabelValues(...string) Gauge { return &noopGauge{} }
+func (n *noopGaugeVec) Reset()                          {}
 
 // noopHistogramVec is a histogram vector that does nothing.
 type noopHistogramVec struct{}
 
 func (n *noopHistogramVec) With(Labels) Histogram               { return &noopHistogram{} }
 func (n *noopHistogramVec) WithLabelValues(...string) Histogram { return &noopHistogram{} }
+func (n *noopHistogramVec) Reset()                              {}
 
 // noopSummaryVec is a summary vector that does nothing.
 type noopSummaryVec struct{}
 
 func (n *noopSummaryVec) With(Labels) Summary               { return &noopSummary{} }
 func (n *noopSummaryVec) WithLabelValues(...string) Summary { return &noopSummary{} }
+func (n *noopSummaryVec) Reset()                            {}
 
 // noopRegistry provides a registry that gathers nothing.
 type noopRegistry struct{}