package metrics
import (
"math"
"sort"
"sync"
"time"
)
// 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(func()) {}
// 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) {
sort.Sort(Int64Slice(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
}
// Int64Slice attaches the methods of sort.Interface to []int64, sorting in increasing order.
type Int64Slice []int64
func (s Int64Slice) Len() int { return len(s) }
func (s Int64Slice) Less(i, j int) bool { return s[i] < s[j] }
func (s Int64Slice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
