forked from rcrowley/go-metrics
/
counter.go
81 lines (66 loc) · 1.64 KB
/
counter.go
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package metrics
import "sync/atomic"
// Counters hold an int64 value that can be incremented and decremented.
//
// This is an interface so as to encourage other structs to implement
// the Counter API as appropriate.
type Counter interface {
Clear()
Count() int64
Dec(int64)
Inc(int64)
}
// Get an existing or create and register a new Counter.
func GetOrRegisterCounter(name string, r Registry) Counter {
if nil == r {
r = DefaultRegistry
}
return r.GetOrRegister(name, NewCounter()).(Counter)
}
// Create a new Counter.
func NewCounter() Counter {
if UseNilMetrics {
return NilCounter{}
}
return &StandardCounter{0}
}
// Create and register a new Counter.
func NewRegisteredCounter(name string, r Registry) Counter {
c := NewCounter()
if nil == r {
r = DefaultRegistry
}
r.Register(name, c)
return c
}
// No-op Counter.
type NilCounter struct{}
// No-op.
func (c NilCounter) Clear() {}
// No-op.
func (c NilCounter) Count() int64 { return 0 }
// No-op.
func (c NilCounter) Dec(i int64) {}
// No-op.
func (c NilCounter) Inc(i int64) {}
// The standard implementation of a Counter uses the sync/atomic package
// to manage a single int64 value.
type StandardCounter struct {
count int64
}
// Clear the counter: set it to zero.
func (c *StandardCounter) Clear() {
atomic.StoreInt64(&c.count, 0)
}
// Return the current count.
func (c *StandardCounter) Count() int64 {
return atomic.LoadInt64(&c.count)
}
// Decrement the counter by the given amount.
func (c *StandardCounter) Dec(i int64) {
atomic.AddInt64(&c.count, -i)
}
// Increment the counter by the given amount.
func (c *StandardCounter) Inc(i int64) {
atomic.AddInt64(&c.count, i)
}