diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/rcrowley/go-metrics/gauge.go')
-rw-r--r-- | Godeps/_workspace/src/github.com/rcrowley/go-metrics/gauge.go | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/github.com/rcrowley/go-metrics/gauge.go b/Godeps/_workspace/src/github.com/rcrowley/go-metrics/gauge.go new file mode 100644 index 000000000..807638a31 --- /dev/null +++ b/Godeps/_workspace/src/github.com/rcrowley/go-metrics/gauge.go @@ -0,0 +1,84 @@ +package metrics + +import "sync/atomic" + +// Gauges hold an int64 value that can be set arbitrarily. +type Gauge interface { + Snapshot() Gauge + Update(int64) + Value() int64 +} + +// GetOrRegisterGauge returns an existing Gauge or constructs and registers a +// new StandardGauge. +func GetOrRegisterGauge(name string, r Registry) Gauge { + if nil == r { + r = DefaultRegistry + } + return r.GetOrRegister(name, NewGauge).(Gauge) +} + +// NewGauge constructs a new StandardGauge. +func NewGauge() Gauge { + if UseNilMetrics { + return NilGauge{} + } + return &StandardGauge{0} +} + +// NewRegisteredGauge constructs and registers a new StandardGauge. +func NewRegisteredGauge(name string, r Registry) Gauge { + c := NewGauge() + if nil == r { + r = DefaultRegistry + } + r.Register(name, c) + return c +} + +// GaugeSnapshot is a read-only copy of another Gauge. +type GaugeSnapshot int64 + +// Snapshot returns the snapshot. +func (g GaugeSnapshot) Snapshot() Gauge { return g } + +// Update panics. +func (GaugeSnapshot) Update(int64) { + panic("Update called on a GaugeSnapshot") +} + +// Value returns the value at the time the snapshot was taken. +func (g GaugeSnapshot) Value() int64 { return int64(g) } + +// NilGauge is a no-op Gauge. +type NilGauge struct{} + +// Snapshot is a no-op. +func (NilGauge) Snapshot() Gauge { return NilGauge{} } + +// Update is a no-op. +func (NilGauge) Update(v int64) {} + +// Value is a no-op. +func (NilGauge) Value() int64 { return 0 } + +// StandardGauge is the standard implementation of a Gauge and uses the +// sync/atomic package to manage a single int64 value. +type StandardGauge struct { + value int64 +} + +// Snapshot returns a read-only copy of the gauge. +func (g *StandardGauge) Snapshot() Gauge { + return GaugeSnapshot(g.Value()) +} + +// Update updates the gauge's value. +func (g *StandardGauge) Update(v int64) { + atomic.StoreInt64(&g.value, v) +} + +// Value returns the gauge's current value. +func (g *StandardGauge) Value() int64 { + return atomic.LoadInt64(&g.value) +} |