116 lines
2.2 KiB
Go
116 lines
2.2 KiB
Go
package slidingwindow
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import "time"
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// Clock specifies the needed time related functions used by the time series.
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// To use a custom clock implement the interface and pass it to the time series constructor.
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// The default clock uses time.Now()
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type Clock interface {
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Now() time.Time
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}
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type slidingWindow struct {
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buffer []float64
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length int
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end time.Time
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start time.Time
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oldest int
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newest int
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step time.Duration
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duration time.Duration
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clock Clock
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}
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var defaultStep = time.Hour * 24
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var defaultDuration = time.Hour * 24 * 7
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type options struct {
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clock Clock
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step time.Duration
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duration time.Duration
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}
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type option func(*options)
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func WithStep(step time.Duration) option {
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return func(o *options) {
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o.step = step
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}
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}
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func WithDuration(duration time.Duration) option {
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return func(o *options) {
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o.duration = duration
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}
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}
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func WithClock(clock Clock) option {
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return func(o *options) {
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o.clock = clock
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}
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}
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func NewSlidingWindow(os ...option) *slidingWindow {
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opts := options{}
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for _, o := range os {
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o(&opts)
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}
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if opts.clock == nil {
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panic("clock not set")
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}
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if opts.step.Nanoseconds() == 0 {
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opts.step = defaultStep
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}
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if opts.duration.Nanoseconds() == 0 {
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opts.duration = defaultDuration
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}
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return newSlidingWindow(opts.step, opts.duration, opts.clock)
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}
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func newSlidingWindow(step time.Duration, duration time.Duration, clock Clock) *slidingWindow {
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length := int(duration / step)
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now := clock.Now()
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return &slidingWindow{
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buffer: make([]float64, length),
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length: length,
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end: now.Truncate(step).Add(-duration),
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start: now,
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step: step,
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duration: duration,
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oldest: 1,
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clock: clock,
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}
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}
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func (sw *slidingWindow) Insert(score float64) {
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sw.advance()
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if score > sw.buffer[sw.newest] {
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sw.buffer[sw.newest] = score
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}
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}
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func (sw *slidingWindow) Max() float64 {
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sw.advance()
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max := 0.0
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for i := range sw.buffer {
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if sw.buffer[i] > max {
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max = sw.buffer[i]
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}
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}
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return max
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}
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func (sw *slidingWindow) advance() {
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newEnd := sw.clock.Now().Truncate(sw.step).Add(-sw.duration)
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for newEnd.After(sw.end) {
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sw.end = sw.end.Add(sw.step)
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sw.buffer[sw.oldest] = 0.0
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sw.newest = sw.oldest
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sw.oldest = (sw.oldest + 1) % sw.length
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}
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}
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