Un-export MetricVec

This is in preparation for "curried" metric vecs, as discussed.

And it's a good thing anyway. The exported MetricVec was from a time
when I thought people would define own Metric types and then create
Vecs of it. That has never happened.

prometheus/counter.go

@@ -74,12 +74,11 @@ func (c *counter) Add(v float64) {
 // CounterVec embeds MetricVec. See there for a full list of methods with
 // detailed documentation.
 type CounterVec struct {
-	*MetricVec
+	*metricVec
 }
 
 // NewCounterVec creates a new CounterVec based on the provided CounterOpts and
-// partitioned by the given label names. At least one label name must be
+// partitioned by the given label names.
-// provided.
 func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
 	desc := NewDesc(
 		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
@@ -88,7 +87,7 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
 		opts.ConstLabels,
 	)
 	return &CounterVec{
-		MetricVec: newMetricVec(desc, func(lvs ...string) Metric {
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
 			result := &counter{value: value{
 				desc:       desc,
 				valType:    CounterValue,
@@ -100,22 +99,51 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
 	}
 }
 
-// GetMetricWithLabelValues replaces the method of the same name in
+// GetMetricWithLabelValues returns the Counter for the given slice of label
-// MetricVec. The difference is that this method returns a Counter and not a
+// values (same order as the VariableLabels in Desc). If that combination of
-// Metric so that no type conversion is required.
+// label values is accessed for the first time, a new Counter is created.
+//
+// It is possible to call this method without using the returned Counter to only
+// create the new Counter but leave it at its starting value 0. See also the
+// SummaryVec example.
+//
+// Keeping the Counter for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Counter from the CounterVec. In that case,
+// the Counter will still exist, but it will not be exported anymore, even if a
+// Counter with the same label values is created later.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
 func (m *CounterVec) GetMetricWithLabelValues(lvs ...string) (Counter, error) {
-	metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...)
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
 	if metric != nil {
 		return metric.(Counter), err
 	}
 	return nil, err
 }
 
-// GetMetricWith replaces the method of the same name in MetricVec. The
+// GetMetricWith returns the Counter for the given Labels map (the label names
-// difference is that this method returns a Counter and not a Metric so that no
+// must match those of the VariableLabels in Desc). If that label map is
-// type conversion is required.
+// accessed for the first time, a new Counter is created. Implications of
+// creating a Counter without using it and keeping the Counter for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
 func (m *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
-	metric, err := m.MetricVec.GetMetricWith(labels)
+	metric, err := m.metricVec.getMetricWith(labels)
 	if metric != nil {
 		return metric.(Counter), err
 	}
@@ -127,14 +155,14 @@ func (m *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Add(42)
 func (m *CounterVec) WithLabelValues(lvs ...string) Counter {
-	return m.MetricVec.WithLabelValues(lvs...).(Counter)
+	return m.metricVec.withLabelValues(lvs...).(Counter)
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 func (m *CounterVec) With(labels Labels) Counter {
-	return m.MetricVec.With(labels).(Counter)
+	return m.metricVec.with(labels).(Counter)
 }
 
 // CounterFunc is a Counter whose value is determined at collect time by calling a

prometheus/gauge.go

@@ -63,12 +63,11 @@ func NewGauge(opts GaugeOpts) Gauge {
 // (e.g. number of operations queued, partitioned by user and operation
 // type). Create instances with NewGaugeVec.
 type GaugeVec struct {
-	*MetricVec
+	*metricVec
 }
 
 // NewGaugeVec creates a new GaugeVec based on the provided GaugeOpts and
-// partitioned by the given label names. At least one label name must be
+// partitioned by the given label names.
-// provided.
 func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
 	desc := NewDesc(
 		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
@@ -77,28 +76,57 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
 		opts.ConstLabels,
 	)
 	return &GaugeVec{
-		MetricVec: newMetricVec(desc, func(lvs ...string) Metric {
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
 			return newValue(desc, GaugeValue, 0, lvs...)
 		}),
 	}
 }
 
-// GetMetricWithLabelValues replaces the method of the same name in
+// GetMetricWithLabelValues returns the Gauge for the given slice of label
-// MetricVec. The difference is that this method returns a Gauge and not a
+// values (same order as the VariableLabels in Desc). If that combination of
-// Metric so that no type conversion is required.
+// label values is accessed for the first time, a new Gauge is created.
+//
+// It is possible to call this method without using the returned Gauge to only
+// create the new Gauge but leave it at its starting value 0. See also the
+// SummaryVec example.
+//
+// Keeping the Gauge for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Gauge from the GaugeVec. In that case, the
+// Gauge will still exist, but it will not be exported anymore, even if a
+// Gauge with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
 func (m *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
-	metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...)
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
 	if metric != nil {
 		return metric.(Gauge), err
 	}
 	return nil, err
 }
 
-// GetMetricWith replaces the method of the same name in MetricVec. The
+// GetMetricWith returns the Gauge for the given Labels map (the label names
-// difference is that this method returns a Gauge and not a Metric so that no
+// must match those of the VariableLabels in Desc). If that label map is
-// type conversion is required.
+// accessed for the first time, a new Gauge is created. Implications of
+// creating a Gauge without using it and keeping the Gauge for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
 func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
-	metric, err := m.MetricVec.GetMetricWith(labels)
+	metric, err := m.metricVec.getMetricWith(labels)
 	if metric != nil {
 		return metric.(Gauge), err
 	}
@@ -110,14 +138,14 @@ func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Add(42)
 func (m *GaugeVec) WithLabelValues(lvs ...string) Gauge {
-	return m.MetricVec.WithLabelValues(lvs...).(Gauge)
+	return m.metricVec.withLabelValues(lvs...).(Gauge)
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 func (m *GaugeVec) With(labels Labels) Gauge {
-	return m.MetricVec.With(labels).(Gauge)
+	return m.metricVec.with(labels).(Gauge)
 }
 
 // GaugeFunc is a Gauge whose value is determined at collect time by calling a

prometheus/histogram.go

@@ -287,12 +287,11 @@ func (h *histogram) Write(out *dto.Metric) error {
 // (e.g. HTTP request latencies, partitioned by status code and method). Create
 // instances with NewHistogramVec.
 type HistogramVec struct {
-	*MetricVec
+	*metricVec
 }
 
 // NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and
-// partitioned by the given label names. At least one label name must be
+// partitioned by the given label names.
-// provided.
 func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
 	desc := NewDesc(
 		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
@@ -301,28 +300,58 @@ func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
 		opts.ConstLabels,
 	)
 	return &HistogramVec{
-		MetricVec: newMetricVec(desc, func(lvs ...string) Metric {
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
 			return newHistogram(desc, opts, lvs...)
 		}),
 	}
 }
 
-// GetMetricWithLabelValues replaces the method of the same name in
+// GetMetricWithLabelValues returns the Histogram for the given slice of label
-// MetricVec. The difference is that this method returns an Observer and not a
+// values (same order as the VariableLabels in Desc). If that combination of
-// Metric so that no type conversion to an Observer is required.
+// label values is accessed for the first time, a new Histogram is created.
+//
+// It is possible to call this method without using the returned Histogram to only
+// create the new Histogram but leave it at its starting value, a Histogram without
+// any observations.
+//
+// Keeping the Histogram for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Histogram from the HistogramVec. In that case, the
+// Histogram will still exist, but it will not be exported anymore, even if a
+// Histogram with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
 func (m *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
-	metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...)
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
 	if metric != nil {
 		return metric.(Observer), err
 	}
 	return nil, err
 }
 
-// GetMetricWith replaces the method of the same name in MetricVec. The
+// GetMetricWith returns the Histogram for the given Labels map (the label names
-// difference is that this method returns an Observer and not a Metric so that no
+// must match those of the VariableLabels in Desc). If that label map is
-// type conversion to an Observer is required.
+// accessed for the first time, a new Histogram is created. Implications of
+// creating a Histogram without using it and keeping the Histogram for later use
+// are the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
 func (m *HistogramVec) GetMetricWith(labels Labels) (Observer, error) {
-	metric, err := m.MetricVec.GetMetricWith(labels)
+	metric, err := m.metricVec.getMetricWith(labels)
 	if metric != nil {
 		return metric.(Observer), err
 	}
@@ -334,14 +363,14 @@ func (m *HistogramVec) GetMetricWith(labels Labels) (Observer, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Observe(42.21)
 func (m *HistogramVec) WithLabelValues(lvs ...string) Observer {
-	return m.MetricVec.WithLabelValues(lvs...).(Observer)
+	return m.metricVec.withLabelValues(lvs...).(Observer)
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
 func (m *HistogramVec) With(labels Labels) Observer {
-	return m.MetricVec.With(labels).(Observer)
+	return m.metricVec.with(labels).(Observer)
 }
 
 type constHistogram struct {

prometheus/summary.go

@@ -399,12 +399,11 @@ func (s quantSort) Less(i, j int) bool {
 // (e.g. HTTP request latencies, partitioned by status code and method). Create
 // instances with NewSummaryVec.
 type SummaryVec struct {
-	*MetricVec
+	*metricVec
 }
 
 // NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and
-// partitioned by the given label names. At least one label name must be
+// partitioned by the given label names.
-// provided.
 func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
 	desc := NewDesc(
 		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
@@ -413,28 +412,58 @@ func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
 		opts.ConstLabels,
 	)
 	return &SummaryVec{
-		MetricVec: newMetricVec(desc, func(lvs ...string) Metric {
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
 			return newSummary(desc, opts, lvs...)
 		}),
 	}
 }
 
-// GetMetricWithLabelValues replaces the method of the same name in MetricVec.
+// GetMetricWithLabelValues returns the Summary for the given slice of label
-// The difference is that this method returns an Observer and not a Metric so
+// values (same order as the VariableLabels in Desc). If that combination of
-// that no type conversion to an Observer is required.
+// label values is accessed for the first time, a new Summary is created.
+//
+// It is possible to call this method without using the returned Summary to only
+// create the new Summary but leave it at its starting value, a Summary without
+// any observations.
+//
+// Keeping the Summary for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Summary from the SummaryVec. In that case, the
+// Summary will still exist, but it will not be exported anymore, even if a
+// Summary with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
 func (m *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
-	metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...)
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
 	if metric != nil {
 		return metric.(Observer), err
 	}
 	return nil, err
 }
 
-// GetMetricWith replaces the method of the same name in MetricVec. The
+// GetMetricWith returns the Summary for the given Labels map (the label names
-// difference is that this method returns an Observer and not a Metric so that
+// must match those of the VariableLabels in Desc). If that label map is
-// no type conversion to an Observer is required.
+// accessed for the first time, a new Summary is created. Implications of
+// creating a Summary without using it and keeping the Summary for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
 func (m *SummaryVec) GetMetricWith(labels Labels) (Observer, error) {
-	metric, err := m.MetricVec.GetMetricWith(labels)
+	metric, err := m.metricVec.getMetricWith(labels)
 	if metric != nil {
 		return metric.(Observer), err
 	}
@@ -446,14 +475,14 @@ func (m *SummaryVec) GetMetricWith(labels Labels) (Observer, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Observe(42.21)
 func (m *SummaryVec) WithLabelValues(lvs ...string) Observer {
-	return m.MetricVec.WithLabelValues(lvs...).(Observer)
+	return m.metricVec.withLabelValues(lvs...).(Observer)
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
 func (m *SummaryVec) With(labels Labels) Observer {
-	return m.MetricVec.With(labels).(Observer)
+	return m.metricVec.with(labels).(Observer)
 }
 
 type constSummary struct {

prometheus/untyped.go

@@ -67,8 +67,7 @@ type UntypedVec struct {
 }
 
 // NewUntypedVec creates a new UntypedVec based on the provided UntypedOpts and
-// partitioned by the given label names. At least one label name must be
+// partitioned by the given label names.
-// provided.
 func NewUntypedVec(opts UntypedOpts, labelNames []string) *UntypedVec {
 	desc := NewDesc(
 		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
@@ -83,22 +82,52 @@ func NewUntypedVec(opts UntypedOpts, labelNames []string) *UntypedVec {
 	}
 }
 
-// GetMetricWithLabelValues replaces the method of the same name in
+// GetMetricWithLabelValues returns the Untyped for the given slice of label
-// MetricVec. The difference is that this method returns an Untyped and not a
+// values (same order as the VariableLabels in Desc). If that combination of
-// Metric so that no type conversion is required.
+// label values is accessed for the first time, a new Untyped is created.
+//
+// It is possible to call this method without using the returned Untyped to only
+// create the new Untyped but leave it at its starting value 0. See also the
+// SummaryVec example.
+//
+// Keeping the Untyped for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Untyped from the UntypedVec. In that case, the
+// Untyped will still exist, but it will not be exported anymore, even if a
+// Untyped with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
 func (m *UntypedVec) GetMetricWithLabelValues(lvs ...string) (Untyped, error) {
-	metric, err := m.metricVec.GetMetricWithLabelValues(lvs...)
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
 	if metric != nil {
 		return metric.(Untyped), err
 	}
 	return nil, err
 }
 
-// GetMetricWith replaces the method of the same name in MetricVec. The
+// GetMetricWith returns the Untyped for the given Labels map (the label names
-// difference is that this method returns an Untyped and not a Metric so that no
+// must match those of the VariableLabels in Desc). If that label map is
-// type conversion is required.
+// accessed for the first time, a new Untyped is created. Implications of
+// creating a Untyped without using it and keeping the Untyped for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
 func (m *UntypedVec) GetMetricWith(labels Labels) (Untyped, error) {
-	metric, err := m.metricVec.GetMetricWith(labels)
+	metric, err := m.metricVec.getMetricWith(labels)
 	if metric != nil {
 		return metric.(Untyped), err
 	}
@@ -110,14 +139,14 @@ func (m *UntypedVec) GetMetricWith(labels Labels) (Untyped, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Add(42)
 func (m *UntypedVec) WithLabelValues(lvs ...string) Untyped {
-	return m.metricVec.WithLabelValues(lvs...).(Untyped)
+	return m.metricVec.withLabelValues(lvs...).(Untyped)
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 func (m *UntypedVec) With(labels Labels) Untyped {
-	return m.metricVec.With(labels).(Untyped)
+	return m.metricVec.with(labels).(Untyped)
 }
 
 // UntypedFunc is an Untyped whose value is determined at collect time by

prometheus/vec.go

@@ -20,12 +20,12 @@ import (
 	"github.com/prometheus/common/model"
 )
 
-// MetricVec is a Collector to bundle metrics of the same name that
+// metricVec is a Collector to bundle metrics of the same name that differ in
-// differ in their label values. MetricVec is usually not used directly but as a
+// their label values. metricVec is not used directly (and therefore
-// building block for implementations of vectors of a given metric
+// unexported). It is used as a building block for implementations of vectors of
-// type. GaugeVec, CounterVec, SummaryVec, and UntypedVec are examples already
+// a given metric type, like GaugeVec, CounterVec, SummaryVec, HistogramVec, and
-// provided in this package.
+// UntypedVec.
-type MetricVec struct {
+type metricVec struct {
 	mtx      sync.RWMutex // Protects the children.
 	children map[uint64][]metricWithLabelValues
 	desc     *Desc
@@ -37,8 +37,8 @@ type MetricVec struct {
 
 // newMetricVec returns an initialized MetricVec. The concrete value is
 // returned for embedding into another struct.
-func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *MetricVec {
+func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *metricVec {
-	return &MetricVec{
+	return &metricVec{
 		children:    map[uint64][]metricWithLabelValues{},
 		desc:        desc,
 		newMetric:   newMetric,
@@ -56,12 +56,12 @@ type metricWithLabelValues struct {
 
 // Describe implements Collector. The length of the returned slice
 // is always one.
-func (m *MetricVec) Describe(ch chan<- *Desc) {
+func (m *metricVec) Describe(ch chan<- *Desc) {
 	ch <- m.desc
 }
 
 // Collect implements Collector.
-func (m *MetricVec) Collect(ch chan<- Metric) {
+func (m *metricVec) Collect(ch chan<- Metric) {
 	m.mtx.RLock()
 	defer m.mtx.RUnlock()
 
@@ -72,31 +72,7 @@ func (m *MetricVec) Collect(ch chan<- Metric) {
 	}
 }
 
-// GetMetricWithLabelValues returns the Metric for the given slice of label
+func (m *metricVec) getMetricWithLabelValues(lvs ...string) (Metric, error) {
-// values (same order as the VariableLabels in Desc). If that combination of
-// label values is accessed for the first time, a new Metric is created.
-//
-// It is possible to call this method without using the returned Metric to only
-// create the new Metric but leave it at its start value (e.g. a Summary or
-// Histogram without any observations). See also the SummaryVec example.
-//
-// Keeping the Metric for later use is possible (and should be considered if
-// performance is critical), but keep in mind that Reset, DeleteLabelValues and
-// Delete can be used to delete the Metric from the MetricVec. In that case, the
-// Metric will still exist, but it will not be exported anymore, even if a
-// Metric with the same label values is created later. See also the CounterVec
-// example.
-//
-// An error is returned if the number of label values is not the same as the
-// number of VariableLabels in Desc.
-//
-// Note that for more than one label value, this method is prone to mistakes
-// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
-// an alternative to avoid that type of mistake. For higher label numbers, the
-// latter has a much more readable (albeit more verbose) syntax, but it comes
-// with a performance overhead (for creating and processing the Labels map).
-// See also the GaugeVec example.
-func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
 	h, err := m.hashLabelValues(lvs)
 	if err != nil {
 		return nil, err
@@ -105,19 +81,7 @@ func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
 	return m.getOrCreateMetricWithLabelValues(h, lvs), nil
 }
 
-// GetMetricWith returns the Metric for the given Labels map (the label names
+func (m *metricVec) getMetricWith(labels Labels) (Metric, error) {
-// must match those of the VariableLabels in Desc). If that label map is
-// accessed for the first time, a new Metric is created. Implications of
-// creating a Metric without using it and keeping the Metric for later use are
-// the same as for GetMetricWithLabelValues.
-//
-// An error is returned if the number and names of the Labels are inconsistent
-// with those of the VariableLabels in Desc.
-//
-// This method is used for the same purpose as
-// GetMetricWithLabelValues(...string). See there for pros and cons of the two
-// methods.
-func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
 	h, err := m.hashLabels(labels)
 	if err != nil {
 		return nil, err
@@ -126,22 +90,16 @@ func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
 	return m.getOrCreateMetricWithLabels(h, labels), nil
 }
 
-// WithLabelValues works as GetMetricWithLabelValues, but panics if an error
+func (m *metricVec) withLabelValues(lvs ...string) Metric {
-// occurs. The method allows neat syntax like:
+	metric, err := m.getMetricWithLabelValues(lvs...)
-//     httpReqs.WithLabelValues("404", "POST").Inc()
-func (m *MetricVec) WithLabelValues(lvs ...string) Metric {
-	metric, err := m.GetMetricWithLabelValues(lvs...)
 	if err != nil {
 		panic(err)
 	}
 	return metric
 }
 
-// With works as GetMetricWith, but panics if an error occurs. The method allows
+func (m *metricVec) with(labels Labels) Metric {
-// neat syntax like:
+	metric, err := m.getMetricWith(labels)
-//     httpReqs.With(Labels{"status":"404", "method":"POST"}).Inc()
-func (m *MetricVec) With(labels Labels) Metric {
-	metric, err := m.GetMetricWith(labels)
 	if err != nil {
 		panic(err)
 	}
@@ -153,8 +111,8 @@ func (m *MetricVec) With(labels Labels) Metric {
 // returns true if a metric was deleted.
 //
 // It is not an error if the number of label values is not the same as the
-// number of VariableLabels in Desc.  However, such inconsistent label count can
+// number of VariableLabels in Desc. However, such inconsistent label count can
-// never match an actual Metric, so the method will always return false in that
+// never match an actual metric, so the method will always return false in that
 // case.
 //
 // Note that for more than one label value, this method is prone to mistakes
@@ -163,7 +121,7 @@ func (m *MetricVec) With(labels Labels) Metric {
 // latter has a much more readable (albeit more verbose) syntax, but it comes
 // with a performance overhead (for creating and processing the Labels map).
 // See also the CounterVec example.
-func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
+func (m *metricVec) DeleteLabelValues(lvs ...string) bool {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
 
@@ -178,13 +136,13 @@ func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
 // passed in as labels. It returns true if a metric was deleted.
 //
 // It is not an error if the number and names of the Labels are inconsistent
-// with those of the VariableLabels in the Desc of the MetricVec. However, such
+// with those of the VariableLabels in Desc. However, such inconsistent Labels
-// inconsistent Labels can never match an actual Metric, so the method will
+// can never match an actual metric, so the method will always return false in
-// always return false in that case.
+// that case.
 //
 // 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 {
+func (m *metricVec) Delete(labels Labels) bool {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
 
@@ -199,7 +157,7 @@ func (m *MetricVec) Delete(labels Labels) bool {
 // deleteByHashWithLabelValues removes the metric from the hash bucket h. If
 // there are multiple matches in the bucket, use lvs to select a metric and
 // remove only that metric.
-func (m *MetricVec) deleteByHashWithLabelValues(h uint64, lvs []string) bool {
+func (m *metricVec) deleteByHashWithLabelValues(h uint64, lvs []string) bool {
 	metrics, ok := m.children[h]
 	if !ok {
 		return false
@@ -221,7 +179,7 @@ func (m *MetricVec) deleteByHashWithLabelValues(h uint64, lvs []string) bool {
 // deleteByHashWithLabels removes the metric from the hash bucket h. If there
 // are multiple matches in the bucket, use lvs to select a metric and remove
 // only that metric.
-func (m *MetricVec) deleteByHashWithLabels(h uint64, labels Labels) bool {
+func (m *metricVec) deleteByHashWithLabels(h uint64, labels Labels) bool {
 	metrics, ok := m.children[h]
 	if !ok {
 		return false
@@ -240,7 +198,7 @@ func (m *MetricVec) deleteByHashWithLabels(h uint64, labels Labels) bool {
 }
 
 // Reset deletes all metrics in this vector.
-func (m *MetricVec) Reset() {
+func (m *metricVec) Reset() {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
 
@@ -249,7 +207,7 @@ func (m *MetricVec) Reset() {
 	}
 }
 
-func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
+func (m *metricVec) hashLabelValues(vals []string) (uint64, error) {
 	if len(vals) != len(m.desc.variableLabels) {
 		return 0, errInconsistentCardinality
 	}
@@ -261,7 +219,7 @@ func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
 	return h, nil
 }
 
-func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
+func (m *metricVec) hashLabels(labels Labels) (uint64, error) {
 	if len(labels) != len(m.desc.variableLabels) {
 		return 0, errInconsistentCardinality
 	}
@@ -281,9 +239,9 @@ func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
 // or creates it and returns the new one.
 //
 // This function holds the mutex.
-func (m *MetricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string) Metric {
+func (m *metricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string) Metric {
 	m.mtx.RLock()
-	metric, ok := m.getMetricWithLabelValues(hash, lvs)
+	metric, ok := m.getMetricWithHashAndLabelValues(hash, lvs)
 	m.mtx.RUnlock()
 	if ok {
 		return metric
@@ -291,7 +249,7 @@ func (m *MetricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string)
 
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
-	metric, ok = m.getMetricWithLabelValues(hash, lvs)
+	metric, ok = m.getMetricWithHashAndLabelValues(hash, lvs)
 	if !ok {
 		// Copy to avoid allocation in case wo don't go down this code path.
 		copiedLVs := make([]string, len(lvs))
@@ -306,9 +264,9 @@ func (m *MetricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string)
 // or creates it and returns the new one.
 //
 // This function holds the mutex.
-func (m *MetricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metric {
+func (m *metricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metric {
 	m.mtx.RLock()
-	metric, ok := m.getMetricWithLabels(hash, labels)
+	metric, ok := m.getMetricWithHashAndLabels(hash, labels)
 	m.mtx.RUnlock()
 	if ok {
 		return metric
@@ -316,7 +274,7 @@ func (m *MetricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metr
 
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
-	metric, ok = m.getMetricWithLabels(hash, labels)
+	metric, ok = m.getMetricWithHashAndLabels(hash, labels)
 	if !ok {
 		lvs := m.extractLabelValues(labels)
 		metric = m.newMetric(lvs...)
@@ -325,9 +283,9 @@ func (m *MetricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metr
 	return metric
 }
 
-// getMetricWithLabelValues gets a metric while handling possible collisions in
+// getMetricWithHashAndLabelValues gets a metric while handling possible
-// the hash space. Must be called while holding read mutex.
+// collisions in the hash space. Must be called while holding the read mutex.
-func (m *MetricVec) getMetricWithLabelValues(h uint64, lvs []string) (Metric, bool) {
+func (m *metricVec) getMetricWithHashAndLabelValues(h uint64, lvs []string) (Metric, bool) {
 	metrics, ok := m.children[h]
 	if ok {
 		if i := m.findMetricWithLabelValues(metrics, lvs); i < len(metrics) {
@@ -337,9 +295,9 @@ func (m *MetricVec) getMetricWithLabelValues(h uint64, lvs []string) (Metric, bo
 	return nil, false
 }
 
-// getMetricWithLabels gets a metric while handling possible collisions in
+// getMetricWithHashAndLabels gets a metric while handling possible collisions in
 // the hash space. Must be called while holding read mutex.
-func (m *MetricVec) getMetricWithLabels(h uint64, labels Labels) (Metric, bool) {
+func (m *metricVec) getMetricWithHashAndLabels(h uint64, labels Labels) (Metric, bool) {
 	metrics, ok := m.children[h]
 	if ok {
 		if i := m.findMetricWithLabels(metrics, labels); i < len(metrics) {
@@ -351,7 +309,7 @@ func (m *MetricVec) getMetricWithLabels(h uint64, labels Labels) (Metric, bool)
 
 // findMetricWithLabelValues returns the index of the matching metric or
 // len(metrics) if not found.
-func (m *MetricVec) findMetricWithLabelValues(metrics []metricWithLabelValues, lvs []string) int {
+func (m *metricVec) findMetricWithLabelValues(metrics []metricWithLabelValues, lvs []string) int {
 	for i, metric := range metrics {
 		if m.matchLabelValues(metric.values, lvs) {
 			return i
@@ -362,7 +320,7 @@ func (m *MetricVec) findMetricWithLabelValues(metrics []metricWithLabelValues, l
 
 // findMetricWithLabels returns the index of the matching metric or len(metrics)
 // if not found.
-func (m *MetricVec) findMetricWithLabels(metrics []metricWithLabelValues, labels Labels) int {
+func (m *metricVec) findMetricWithLabels(metrics []metricWithLabelValues, labels Labels) int {
 	for i, metric := range metrics {
 		if m.matchLabels(metric.values, labels) {
 			return i
@@ -371,7 +329,7 @@ func (m *MetricVec) findMetricWithLabels(metrics []metricWithLabelValues, labels
 	return len(metrics)
 }
 
-func (m *MetricVec) matchLabelValues(values []string, lvs []string) bool {
+func (m *metricVec) matchLabelValues(values []string, lvs []string) bool {
 	if len(values) != len(lvs) {
 		return false
 	}
@@ -383,7 +341,7 @@ func (m *MetricVec) matchLabelValues(values []string, lvs []string) bool {
 	return true
 }
 
-func (m *MetricVec) matchLabels(values []string, labels Labels) bool {
+func (m *metricVec) matchLabels(values []string, labels Labels) bool {
 	if len(labels) != len(values) {
 		return false
 	}
@@ -395,7 +353,7 @@ func (m *MetricVec) matchLabels(values []string, labels Labels) bool {
 	return true
 }
 
-func (m *MetricVec) extractLabelValues(labels Labels) []string {
+func (m *metricVec) extractLabelValues(labels Labels) []string {
 	labelValues := make([]string, len(labels))
 	for i, k := range m.desc.variableLabels {
 		labelValues[i] = labels[k]