diff options
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/gauge.go')
| -rw-r--r-- | vendor/github.com/prometheus/client_golang/prometheus/gauge.go | 204 |
1 files changed, 175 insertions, 29 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/gauge.go b/vendor/github.com/prometheus/client_golang/prometheus/gauge.go index 8b70e5141..17c72d7eb 100644 --- a/vendor/github.com/prometheus/client_golang/prometheus/gauge.go +++ b/vendor/github.com/prometheus/client_golang/prometheus/gauge.go @@ -13,6 +13,14 @@ package prometheus +import ( + "math" + "sync/atomic" + "time" + + dto "github.com/prometheus/client_model/go" +) + // Gauge is a Metric that represents a single numerical value that can // arbitrarily go up and down. // @@ -27,29 +35,95 @@ type Gauge interface { // Set sets the Gauge to an arbitrary value. Set(float64) - // Inc increments the Gauge by 1. + // Inc increments the Gauge by 1. Use Add to increment it by arbitrary + // values. Inc() - // Dec decrements the Gauge by 1. + // Dec decrements the Gauge by 1. Use Sub to decrement it by arbitrary + // values. Dec() - // Add adds the given value to the Gauge. (The value can be - // negative, resulting in a decrease of the Gauge.) + // Add adds the given value to the Gauge. (The value can be negative, + // resulting in a decrease of the Gauge.) Add(float64) // Sub subtracts the given value from the Gauge. (The value can be // negative, resulting in an increase of the Gauge.) Sub(float64) + + // SetToCurrentTime sets the Gauge to the current Unix time in seconds. + SetToCurrentTime() } // GaugeOpts is an alias for Opts. See there for doc comments. type GaugeOpts Opts // NewGauge creates a new Gauge based on the provided GaugeOpts. +// +// The returned implementation is optimized for a fast Set method. If you have a +// choice for managing the value of a Gauge via Set vs. Inc/Dec/Add/Sub, pick +// the former. For example, the Inc method of the returned Gauge is slower than +// the Inc method of a Counter returned by NewCounter. This matches the typical +// scenarios for Gauges and Counters, where the former tends to be Set-heavy and +// the latter Inc-heavy. func NewGauge(opts GaugeOpts) Gauge { - return newValue(NewDesc( + desc := NewDesc( BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), opts.Help, nil, opts.ConstLabels, - ), GaugeValue, 0) + ) + result := &gauge{desc: desc, labelPairs: desc.constLabelPairs} + result.init(result) // Init self-collection. + return result +} + +type gauge struct { + // valBits contains the bits of the represented float64 value. It has + // to go first in the struct to guarantee alignment for atomic + // operations. http://golang.org/pkg/sync/atomic/#pkg-note-BUG + valBits uint64 + + selfCollector + + desc *Desc + labelPairs []*dto.LabelPair +} + +func (g *gauge) Desc() *Desc { + return g.desc +} + +func (g *gauge) Set(val float64) { + atomic.StoreUint64(&g.valBits, math.Float64bits(val)) +} + +func (g *gauge) SetToCurrentTime() { + g.Set(float64(time.Now().UnixNano()) / 1e9) +} + +func (g *gauge) Inc() { + g.Add(1) +} + +func (g *gauge) Dec() { + g.Add(-1) +} + +func (g *gauge) Add(val float64) { + for { + oldBits := atomic.LoadUint64(&g.valBits) + newBits := math.Float64bits(math.Float64frombits(oldBits) + val) + if atomic.CompareAndSwapUint64(&g.valBits, oldBits, newBits) { + return + } + } +} + +func (g *gauge) Sub(val float64) { + g.Add(val * -1) +} + +func (g *gauge) Write(out *dto.Metric) error { + val := math.Float64frombits(atomic.LoadUint64(&g.valBits)) + return populateMetric(GaugeValue, val, g.labelPairs, out) } // GaugeVec is a Collector that bundles a set of Gauges that all share the same @@ -58,12 +132,11 @@ 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 -// provided. +// partitioned by the given label names. func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec { desc := NewDesc( BuildFQName(opts.Namespace, opts.Subsystem, opts.Name), @@ -72,28 +145,62 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec { opts.ConstLabels, ) return &GaugeVec{ - MetricVec: newMetricVec(desc, func(lvs ...string) Metric { - return newValue(desc, GaugeValue, 0, lvs...) + metricVec: newMetricVec(desc, func(lvs ...string) Metric { + if len(lvs) != len(desc.variableLabels) { + panic(errInconsistentCardinality) + } + result := &gauge{desc: desc, labelPairs: makeLabelPairs(desc, lvs)} + result.init(result) // Init self-collection. + return result }), } } -// GetMetricWithLabelValues replaces the method of the same name in -// MetricVec. The difference is that this method returns a Gauge and not a -// Metric so that no type conversion is required. -func (m *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) { - metric, err := m.MetricVec.GetMetricWithLabelValues(lvs...) +// GetMetricWithLabelValues returns the Gauge for the given slice of label +// values (same order as the VariableLabels in Desc). If that combination of +// 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 (minus any curried labels). +// +// 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 (v *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) { + metric, err := v.metricVec.getMetricWithLabelValues(lvs...) if metric != nil { return metric.(Gauge), err } return nil, err } -// GetMetricWith replaces the method of the same name in MetricVec. The -// difference is that this method returns a Gauge and not a Metric so that no -// type conversion is required. -func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) { - metric, err := m.MetricVec.GetMetricWith(labels) +// GetMetricWith returns the Gauge for the given Labels map (the label names +// must match those of the VariableLabels in Desc). If that label map is +// 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 (minus any curried labels). +// +// This method is used for the same purpose as +// GetMetricWithLabelValues(...string). See there for pros and cons of the two +// methods. +func (v *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) { + metric, err := v.metricVec.getMetricWith(labels) if metric != nil { return metric.(Gauge), err } @@ -101,18 +208,57 @@ func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) { } // WithLabelValues works as GetMetricWithLabelValues, but panics where -// GetMetricWithLabelValues would have returned an error. By not returning an -// error, WithLabelValues allows shortcuts like +// GetMetricWithLabelValues would have returned an error. Not returning an +// error allows shortcuts like // myVec.WithLabelValues("404", "GET").Add(42) -func (m *GaugeVec) WithLabelValues(lvs ...string) Gauge { - return m.MetricVec.WithLabelValues(lvs...).(Gauge) +func (v *GaugeVec) WithLabelValues(lvs ...string) Gauge { + g, err := v.GetMetricWithLabelValues(lvs...) + if err != nil { + panic(err) + } + return g } // 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) +// returned an error. Not returning an error allows shortcuts like +// myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Add(42) +func (v *GaugeVec) With(labels Labels) Gauge { + g, err := v.GetMetricWith(labels) + if err != nil { + panic(err) + } + return g +} + +// CurryWith returns a vector curried with the provided labels, i.e. the +// returned vector has those labels pre-set for all labeled operations performed +// on it. The cardinality of the curried vector is reduced accordingly. The +// order of the remaining labels stays the same (just with the curried labels +// taken out of the sequence – which is relevant for the +// (GetMetric)WithLabelValues methods). It is possible to curry a curried +// vector, but only with labels not yet used for currying before. +// +// The metrics contained in the GaugeVec are shared between the curried and +// uncurried vectors. They are just accessed differently. Curried and uncurried +// vectors behave identically in terms of collection. Only one must be +// registered with a given registry (usually the uncurried version). The Reset +// method deletes all metrics, even if called on a curried vector. +func (v *GaugeVec) CurryWith(labels Labels) (*GaugeVec, error) { + vec, err := v.curryWith(labels) + if vec != nil { + return &GaugeVec{vec}, err + } + return nil, err +} + +// MustCurryWith works as CurryWith but panics where CurryWith would have +// returned an error. +func (v *GaugeVec) MustCurryWith(labels Labels) *GaugeVec { + vec, err := v.CurryWith(labels) + if err != nil { + panic(err) + } + return vec } // GaugeFunc is a Gauge whose value is determined at collect time by calling a |