package metrics

import _ "sync/atomic"

// Gauges hold an int64 value that can be set arbitrarily.
//
// This is an interface so as to encourage other structs to implement
// the Gauge API as appropriate.
type Gauge interface {
	Update(int64)
	Value() int64
}

// The standard implementation of a Gauge uses the sync/atomic package
// to manage a single int64 value.  When the latest weeklies land in a
// release, atomic.LoadInt64 will be available and this code will become
// safe on 32-bit architectures.
type StandardGauge struct {
	value int64
}

// Create a new gauge.
func NewGauge() *StandardGauge {
	return &StandardGauge{0}
}

// Update the gauge's value.
func (g *StandardGauge) Update(v int64) {
	g.value = v
}

// Return the gauge's current value.
func (g *StandardGauge) Value() int64 {
	return g.value
}