forked from TrueCloudLab/distribution
91 lines
2.3 KiB
Go
91 lines
2.3 KiB
Go
package metrics
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import "sync"
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// GaugeFloat64s hold a float64 value that can be set arbitrarily.
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type GaugeFloat64 interface {
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Snapshot() GaugeFloat64
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Update(float64)
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Value() float64
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}
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// GetOrRegisterGaugeFloat64 returns an existing GaugeFloat64 or constructs and registers a
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// new StandardGaugeFloat64.
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func GetOrRegisterGaugeFloat64(name string, r Registry) GaugeFloat64 {
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if nil == r {
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r = DefaultRegistry
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}
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return r.GetOrRegister(name, NewGaugeFloat64()).(GaugeFloat64)
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}
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// NewGaugeFloat64 constructs a new StandardGaugeFloat64.
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func NewGaugeFloat64() GaugeFloat64 {
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if UseNilMetrics {
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return NilGaugeFloat64{}
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}
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return &StandardGaugeFloat64{
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value: 0.0,
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}
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}
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// NewRegisteredGaugeFloat64 constructs and registers a new StandardGaugeFloat64.
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func NewRegisteredGaugeFloat64(name string, r Registry) GaugeFloat64 {
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c := NewGaugeFloat64()
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if nil == r {
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r = DefaultRegistry
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}
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r.Register(name, c)
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return c
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}
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// GaugeFloat64Snapshot is a read-only copy of another GaugeFloat64.
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type GaugeFloat64Snapshot float64
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// Snapshot returns the snapshot.
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func (g GaugeFloat64Snapshot) Snapshot() GaugeFloat64 { return g }
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// Update panics.
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func (GaugeFloat64Snapshot) Update(float64) {
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panic("Update called on a GaugeFloat64Snapshot")
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}
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// Value returns the value at the time the snapshot was taken.
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func (g GaugeFloat64Snapshot) Value() float64 { return float64(g) }
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// NilGauge is a no-op Gauge.
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type NilGaugeFloat64 struct{}
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// Snapshot is a no-op.
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func (NilGaugeFloat64) Snapshot() GaugeFloat64 { return NilGaugeFloat64{} }
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// Update is a no-op.
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func (NilGaugeFloat64) Update(v float64) {}
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// Value is a no-op.
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func (NilGaugeFloat64) Value() float64 { return 0.0 }
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// StandardGaugeFloat64 is the standard implementation of a GaugeFloat64 and uses
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// sync.Mutex to manage a single float64 value.
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type StandardGaugeFloat64 struct {
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mutex sync.Mutex
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value float64
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}
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// Snapshot returns a read-only copy of the gauge.
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func (g *StandardGaugeFloat64) Snapshot() GaugeFloat64 {
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return GaugeFloat64Snapshot(g.Value())
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}
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// Update updates the gauge's value.
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func (g *StandardGaugeFloat64) Update(v float64) {
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g.mutex.Lock()
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defer g.mutex.Unlock()
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g.value = v
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}
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// Value returns the gauge's current value.
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func (g *StandardGaugeFloat64) Value() float64 {
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g.mutex.Lock()
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defer g.mutex.Unlock()
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return g.value
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}
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