Merge pull request #67 from getamis/add-gauge-vec

metrics: add gauge vec

metrics/dummy.go

@@ -50,6 +50,10 @@ func (d *DummyRegistry) NewGauge(key string, opts ...Option) Gauge {
 	return &dummyGauge{}
 }
 
+func (d *DummyRegistry) NewGaugeVec(key string, labels []string, opts ...Option) GaugeVec {
+	return &dummyGaugeVec{}
+}
+
 func (d *DummyRegistry) NewHistogram(key string, opts ...Option) Histogram {
 	return &dummyHistogram{}
 }
@@ -93,6 +97,15 @@ type dummyGauge struct{}
 
 func (d *dummyGauge) Set(float64) {}
 
+type dummyGaugeVec struct{}
+
+func (d *dummyGaugeVec) GetMetricWith(MetricsLabels) (Gauge, error) {
+	return &dummyGauge{}, nil
+}
+func (d *dummyGaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
+	return &dummyGauge{}, nil
+}
+
 type dummyHistogram struct{}
 
 func (d *dummyHistogram) Observe(float64) {}

metrics/metrics.go

@@ -48,6 +48,12 @@ type Gauge interface {
 	Set(float64)
 }
 
+// GaugeVec is returned by NewGaugeVec.
+type GaugeVec interface {
+	GetMetricWith(MetricsLabels) (Gauge, error)
+	GetMetricWithLabelValues(lvs ...string) (Gauge, error)
+}
+
 // A Histogram counts individual observations from an event or sample stream in
 // configurable buckets. Similar to a summary, it also provides a sum of
 // observations and an observation count.

metrics/prometheus.go

@@ -145,6 +145,30 @@ func (p *PrometheusRegistry) NewGauge(key string, opts ...Option) Gauge {
 	return g
 }
 
+func (p *PrometheusRegistry) NewGaugeVec(key string, labelNames []string, opts ...Option) GaugeVec {
+	options := NewOptions(p.namespace, "", p.labels)
+	for _, fn := range opts {
+		fn(options)
+	}
+	cnt := prom.NewGaugeVec(prom.GaugeOpts{
+		Namespace:   options.Namespace,
+		Subsystem:   options.Subsystem,
+		Name:        key,
+		Help:        key,
+		ConstLabels: prom.Labels(options.Labels),
+	}, labelNames)
+	err := p.registry.Register(cnt)
+	if err != nil {
+		reg, ok := err.(prom.AlreadyRegisteredError)
+		if ok {
+			existingCV := reg.ExistingCollector.(*prom.GaugeVec)
+			return &gaugeVec{existingCV}
+		}
+		log.Warn("Failed to register a gauge vec", "key", key, "err", err)
+	}
+	return &gaugeVec{cnt}
+}
+
 func (p *PrometheusRegistry) NewHistogram(key string, opts ...Option) Histogram {
 	options := NewOptions(p.namespace, "", p.labels)
 	for _, fn := range opts {
@@ -274,6 +298,19 @@ func (c *counterVec) GetMetricWithLabelValues(lvs ...string) (Counter, error) {
 	return c.CounterVec.GetMetricWithLabelValues(lvs...)
 }
 
+// -----------------------------------------------------------------------------
+// gaugeVec
+type gaugeVec struct {
+	*prom.GaugeVec
+}
+
+func (c *gaugeVec) GetMetricWith(labels MetricsLabels) (Gauge, error) {
+	return c.GaugeVec.GetMetricWith(labels)
+}
+func (c *gaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
+	return c.GaugeVec.GetMetricWithLabelValues(lvs...)
+}
+
 // -----------------------------------------------------------------------------
 // histogramVec
 type histogramVec struct {

metrics/registery.go

@@ -44,6 +44,7 @@ type Registry interface {
 	NewServerMetrics(opts ...Option) ServerMetrics
 	NewCounter(key string, opts ...Option) Counter
 	NewGauge(key string, opts ...Option) Gauge
+	NewGaugeVec(key string, labels []string, opts ...Option) GaugeVec
 	NewHistogram(key string, opts ...Option) Histogram
 	NewHistogramVec(key string, labels []string, opts ...Option) HistogramVec
 	NewCounterVec(key string, labels []string, opts ...Option) CounterVec
@@ -70,6 +71,10 @@ func NewGauge(key string, opts ...Option) Gauge {
 	return DefaultRegistry.NewGauge(key, opts...)
 }
 
+func NewGaugeVec(key string, labels []string, opts ...Option) GaugeVec {
+	return DefaultRegistry.NewGaugeVec(key, labels, opts...)
+}
+
 func NewHistogram(key string, opts ...Option) Histogram {
 	return DefaultRegistry.NewHistogram(key, opts...)
 }