99 lines
2.3 KiB
Go
99 lines
2.3 KiB
Go
package metrics
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import "sync/atomic"
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// GaugeSnapshot contains a readonly int64.
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type GaugeSnapshot interface {
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Value() int64
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}
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// Gauge holds an int64 value that can be set arbitrarily.
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type Gauge interface {
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Snapshot() GaugeSnapshot
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Update(int64)
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UpdateIfGt(int64)
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Dec(int64)
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Inc(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 !Enabled {
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return NilGauge{}
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}
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return &StandardGauge{}
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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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// 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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func (NilGauge) Snapshot() GaugeSnapshot { return (*emptySnapshot)(nil) }
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func (NilGauge) Update(v int64) {}
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func (NilGauge) UpdateIfGt(v int64) {}
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func (NilGauge) Dec(i int64) {}
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func (NilGauge) Inc(i int64) {}
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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 atomic.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() GaugeSnapshot {
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return gaugeSnapshot(g.value.Load())
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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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g.value.Store(v)
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}
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// UpdateIfGt updates the gauge's value if v is larger then the current value.
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func (g *StandardGauge) UpdateIfGt(v int64) {
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for {
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exist := g.value.Load()
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if exist >= v {
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break
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}
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if g.value.CompareAndSwap(exist, v) {
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break
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}
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}
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}
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// Dec decrements the gauge's current value by the given amount.
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func (g *StandardGauge) Dec(i int64) {
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g.value.Add(-i)
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}
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// Inc increments the gauge's current value by the given amount.
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func (g *StandardGauge) Inc(i int64) {
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g.value.Add(i)
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}
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