package metrics import ( "math" "sync" "time" "golang.org/x/exp/slices" ) // Initial slice capacity for the values stored in a ResettingTimer const InitialResettingTimerSliceCap = 10 // ResettingTimer is used for storing aggregated values for timers, which are reset on every flush interval. type ResettingTimer interface { Values() []int64 Snapshot() ResettingTimer Percentiles([]float64) []int64 Mean() float64 Time(func()) Update(time.Duration) UpdateSince(time.Time) } // GetOrRegisterResettingTimer returns an existing ResettingTimer or constructs and registers a // new StandardResettingTimer. func GetOrRegisterResettingTimer(name string, r Registry) ResettingTimer { if nil == r { r = DefaultRegistry } return r.GetOrRegister(name, NewResettingTimer).(ResettingTimer) } // NewRegisteredResettingTimer constructs and registers a new StandardResettingTimer. func NewRegisteredResettingTimer(name string, r Registry) ResettingTimer { c := NewResettingTimer() if nil == r { r = DefaultRegistry } r.Register(name, c) return c } // NewResettingTimer constructs a new StandardResettingTimer func NewResettingTimer() ResettingTimer { if !Enabled { return NilResettingTimer{} } return &StandardResettingTimer{ values: make([]int64, 0, InitialResettingTimerSliceCap), } } // NilResettingTimer is a no-op ResettingTimer. type NilResettingTimer struct { } // Values is a no-op. func (NilResettingTimer) Values() []int64 { return nil } // Snapshot is a no-op. func (NilResettingTimer) Snapshot() ResettingTimer { return &ResettingTimerSnapshot{ values: []int64{}, } } // Time is a no-op. func (NilResettingTimer) Time(f func()) { f() } // Update is a no-op. func (NilResettingTimer) Update(time.Duration) {} // Percentiles panics. func (NilResettingTimer) Percentiles([]float64) []int64 { panic("Percentiles called on a NilResettingTimer") } // Mean panics. func (NilResettingTimer) Mean() float64 { panic("Mean called on a NilResettingTimer") } // UpdateSince is a no-op. func (NilResettingTimer) UpdateSince(time.Time) {} // StandardResettingTimer is the standard implementation of a ResettingTimer. // and Meter. type StandardResettingTimer struct { values []int64 mutex sync.Mutex } // Values returns a slice with all measurements. func (t *StandardResettingTimer) Values() []int64 { return t.values } // Snapshot resets the timer and returns a read-only copy of its contents. func (t *StandardResettingTimer) Snapshot() ResettingTimer { t.mutex.Lock() defer t.mutex.Unlock() currentValues := t.values t.values = make([]int64, 0, InitialResettingTimerSliceCap) return &ResettingTimerSnapshot{ values: currentValues, } } // Percentiles panics. func (t *StandardResettingTimer) Percentiles([]float64) []int64 { panic("Percentiles called on a StandardResettingTimer") } // Mean panics. func (t *StandardResettingTimer) Mean() float64 { panic("Mean called on a StandardResettingTimer") } // Record the duration of the execution of the given function. func (t *StandardResettingTimer) Time(f func()) { ts := time.Now() f() t.Update(time.Since(ts)) } // Record the duration of an event. func (t *StandardResettingTimer) Update(d time.Duration) { t.mutex.Lock() defer t.mutex.Unlock() t.values = append(t.values, int64(d)) } // Record the duration of an event that started at a time and ends now. func (t *StandardResettingTimer) UpdateSince(ts time.Time) { t.mutex.Lock() defer t.mutex.Unlock() t.values = append(t.values, int64(time.Since(ts))) } // ResettingTimerSnapshot is a point-in-time copy of another ResettingTimer. type ResettingTimerSnapshot struct { values []int64 mean float64 thresholdBoundaries []int64 calculated bool } // Snapshot returns the snapshot. func (t *ResettingTimerSnapshot) Snapshot() ResettingTimer { return t } // Time panics. func (*ResettingTimerSnapshot) Time(func()) { panic("Time called on a ResettingTimerSnapshot") } // Update panics. func (*ResettingTimerSnapshot) Update(time.Duration) { panic("Update called on a ResettingTimerSnapshot") } // UpdateSince panics. func (*ResettingTimerSnapshot) UpdateSince(time.Time) { panic("UpdateSince called on a ResettingTimerSnapshot") } // Values returns all values from snapshot. func (t *ResettingTimerSnapshot) Values() []int64 { return t.values } // Percentiles returns the boundaries for the input percentiles. func (t *ResettingTimerSnapshot) Percentiles(percentiles []float64) []int64 { t.calc(percentiles) return t.thresholdBoundaries } // Mean returns the mean of the snapshotted values func (t *ResettingTimerSnapshot) Mean() float64 { if !t.calculated { t.calc([]float64{}) } return t.mean } func (t *ResettingTimerSnapshot) calc(percentiles []float64) { slices.Sort(t.values) count := len(t.values) if count > 0 { min := t.values[0] max := t.values[count-1] cumulativeValues := make([]int64, count) cumulativeValues[0] = min for i := 1; i < count; i++ { cumulativeValues[i] = t.values[i] + cumulativeValues[i-1] } t.thresholdBoundaries = make([]int64, len(percentiles)) thresholdBoundary := max for i, pct := range percentiles { if count > 1 { var abs float64 if pct >= 0 { abs = pct } else { abs = 100 + pct } // poor man's math.Round(x): // math.Floor(x + 0.5) indexOfPerc := int(math.Floor(((abs / 100.0) * float64(count)) + 0.5)) if pct >= 0 && indexOfPerc > 0 { indexOfPerc -= 1 // index offset=0 } thresholdBoundary = t.values[indexOfPerc] } t.thresholdBoundaries[i] = thresholdBoundary } sum := cumulativeValues[count-1] t.mean = float64(sum) / float64(count) } else { t.thresholdBoundaries = make([]int64, len(percentiles)) t.mean = 0 } t.calculated = true }