85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
package metrics
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import "sync/atomic"
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// Gauges hold an int64 value that can be set arbitrarily.
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type Gauge interface {
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Snapshot() Gauge
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Update(int64)
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Value() int64
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}
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// GetOrRegisterGauge returns an existing Gauge or constructs and registers a
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// new StandardGauge.
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func GetOrRegisterGauge(name string, r Registry) Gauge {
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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, NewGauge).(Gauge)
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}
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// NewGauge constructs a new StandardGauge.
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func NewGauge() Gauge {
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if UseNilMetrics {
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return NilGauge{}
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}
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return &StandardGauge{0}
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}
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// NewRegisteredGauge constructs and registers a new StandardGauge.
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func NewRegisteredGauge(name string, r Registry) Gauge {
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c := NewGauge()
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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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// GaugeSnapshot is a read-only copy of another Gauge.
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type GaugeSnapshot int64
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// Snapshot returns the snapshot.
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func (g GaugeSnapshot) Snapshot() Gauge { return g }
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// Update panics.
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func (GaugeSnapshot) Update(int64) {
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panic("Update called on a GaugeSnapshot")
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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 GaugeSnapshot) Value() int64 { return int64(g) }
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// NilGauge is a no-op Gauge.
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type NilGauge struct{}
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// Snapshot is a no-op.
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func (NilGauge) Snapshot() Gauge { return NilGauge{} }
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// Update is a no-op.
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func (NilGauge) Update(v int64) {}
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// Value is a no-op.
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func (NilGauge) Value() int64 { return 0 }
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// StandardGauge is the standard implementation of a Gauge and uses the
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// sync/atomic package to manage a single int64 value.
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type StandardGauge struct {
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value int64
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}
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// Snapshot returns a read-only copy of the gauge.
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func (g *StandardGauge) Snapshot() Gauge {
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return GaugeSnapshot(g.Value())
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}
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// Update updates the gauge's value.
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func (g *StandardGauge) Update(v int64) {
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atomic.StoreInt64(&g.value, v)
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}
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// Value returns the gauge's current value.
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func (g *StandardGauge) Value() int64 {
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return atomic.LoadInt64(&g.value)
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}
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