diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/rcrowley/go-metrics/ewma.go')
-rw-r--r-- | Godeps/_workspace/src/github.com/rcrowley/go-metrics/ewma.go | 118 |
1 files changed, 0 insertions, 118 deletions
diff --git a/Godeps/_workspace/src/github.com/rcrowley/go-metrics/ewma.go b/Godeps/_workspace/src/github.com/rcrowley/go-metrics/ewma.go deleted file mode 100644 index 694a1d033..000000000 --- a/Godeps/_workspace/src/github.com/rcrowley/go-metrics/ewma.go +++ /dev/null @@ -1,118 +0,0 @@ -package metrics - -import ( - "math" - "sync" - "sync/atomic" -) - -// EWMAs continuously calculate an exponentially-weighted moving average -// based on an outside source of clock ticks. -type EWMA interface { - Rate() float64 - Snapshot() EWMA - Tick() - Update(int64) -} - -// NewEWMA constructs a new EWMA with the given alpha. -func NewEWMA(alpha float64) EWMA { - if UseNilMetrics { - return NilEWMA{} - } - return &StandardEWMA{alpha: alpha} -} - -// NewEWMA1 constructs a new EWMA for a one-minute moving average. -func NewEWMA1() EWMA { - return NewEWMA(1 - math.Exp(-5.0/60.0/1)) -} - -// NewEWMA5 constructs a new EWMA for a five-minute moving average. -func NewEWMA5() EWMA { - return NewEWMA(1 - math.Exp(-5.0/60.0/5)) -} - -// NewEWMA15 constructs a new EWMA for a fifteen-minute moving average. -func NewEWMA15() EWMA { - return NewEWMA(1 - math.Exp(-5.0/60.0/15)) -} - -// EWMASnapshot is a read-only copy of another EWMA. -type EWMASnapshot float64 - -// Rate returns the rate of events per second at the time the snapshot was -// taken. -func (a EWMASnapshot) Rate() float64 { return float64(a) } - -// Snapshot returns the snapshot. -func (a EWMASnapshot) Snapshot() EWMA { return a } - -// Tick panics. -func (EWMASnapshot) Tick() { - panic("Tick called on an EWMASnapshot") -} - -// Update panics. -func (EWMASnapshot) Update(int64) { - panic("Update called on an EWMASnapshot") -} - -// NilEWMA is a no-op EWMA. -type NilEWMA struct{} - -// Rate is a no-op. -func (NilEWMA) Rate() float64 { return 0.0 } - -// Snapshot is a no-op. -func (NilEWMA) Snapshot() EWMA { return NilEWMA{} } - -// Tick is a no-op. -func (NilEWMA) Tick() {} - -// Update is a no-op. -func (NilEWMA) Update(n int64) {} - -// StandardEWMA is the standard implementation of an EWMA and tracks the number -// of uncounted events and processes them on each tick. It uses the -// sync/atomic package to manage uncounted events. -type StandardEWMA struct { - uncounted int64 // /!\ this should be the first member to ensure 64-bit alignment - alpha float64 - rate float64 - init bool - mutex sync.Mutex -} - -// Rate returns the moving average rate of events per second. -func (a *StandardEWMA) Rate() float64 { - a.mutex.Lock() - defer a.mutex.Unlock() - return a.rate * float64(1e9) -} - -// Snapshot returns a read-only copy of the EWMA. -func (a *StandardEWMA) Snapshot() EWMA { - return EWMASnapshot(a.Rate()) -} - -// Tick ticks the clock to update the moving average. It assumes it is called -// every five seconds. -func (a *StandardEWMA) Tick() { - count := atomic.LoadInt64(&a.uncounted) - atomic.AddInt64(&a.uncounted, -count) - instantRate := float64(count) / float64(5e9) - a.mutex.Lock() - defer a.mutex.Unlock() - if a.init { - a.rate += a.alpha * (instantRate - a.rate) - } else { - a.init = true - a.rate = instantRate - } -} - -// Update adds n uncounted events. -func (a *StandardEWMA) Update(n int64) { - atomic.AddInt64(&a.uncounted, n) -} |