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gauge_float64.go
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gauge_float64.go
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package metrics
import "sync"
// GaugeFloat64s hold a float64 value that can be set arbitrarily.
type GaugeFloat64 interface {
Snapshot() GaugeFloat64
Update(float64)
Value() float64
}
// GetOrRegisterGaugeFloat64 returns an existing GaugeFloat64 or constructs and registers a
// new StandardGaugeFloat64.
func GetOrRegisterGaugeFloat64(name string, r Registry) GaugeFloat64 {
if nil == r {
r = DefaultRegistry
}
return r.GetOrRegister(name, NewGaugeFloat64()).(GaugeFloat64)
}
// NewGaugeFloat64 constructs a new StandardGaugeFloat64.
func NewGaugeFloat64() GaugeFloat64 {
if UseNilMetrics {
return NilGaugeFloat64{}
}
return &StandardGaugeFloat64{
value: 0.0,
}
}
// NewRegisteredGaugeFloat64 constructs and registers a new StandardGaugeFloat64.
func NewRegisteredGaugeFloat64(name string, r Registry) GaugeFloat64 {
c := NewGaugeFloat64()
if nil == r {
r = DefaultRegistry
}
r.Register(name, c)
return c
}
// GaugeFloat64Snapshot is a read-only copy of another GaugeFloat64.
type GaugeFloat64Snapshot float64
// Snapshot returns the snapshot.
func (g GaugeFloat64Snapshot) Snapshot() GaugeFloat64 { return g }
// Update panics.
func (GaugeFloat64Snapshot) Update(float64) {
panic("Update called on a GaugeFloat64Snapshot")
}
// Value returns the value at the time the snapshot was taken.
func (g GaugeFloat64Snapshot) Value() float64 { return float64(g) }
// NilGauge is a no-op Gauge.
type NilGaugeFloat64 struct{}
// Snapshot is a no-op.
func (NilGaugeFloat64) Snapshot() GaugeFloat64 { return NilGaugeFloat64{} }
// Update is a no-op.
func (NilGaugeFloat64) Update(v float64) {}
// Value is a no-op.
func (NilGaugeFloat64) Value() float64 { return 0.0 }
// StandardGaugeFloat64 is the standard implementation of a GaugeFloat64 and uses
// sync.Mutex to manage a single float64 value.
type StandardGaugeFloat64 struct {
mutex sync.Mutex
value float64
}
// Snapshot returns a read-only copy of the gauge.
func (g *StandardGaugeFloat64) Snapshot() GaugeFloat64 {
return GaugeFloat64Snapshot(g.Value())
}
// Update updates the gauge's value.
func (g *StandardGaugeFloat64) Update(v float64) {
g.mutex.Lock()
defer g.mutex.Unlock()
g.value = v
}
// Value returns the gauge's current value.
func (g *StandardGaugeFloat64) Value() float64 {
g.mutex.Lock()
defer g.mutex.Unlock()
return g.value
}