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metrics_utils.go
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/
metrics_utils.go
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package utils
import (
"sync"
"github.com/rcrowley/go-metrics"
)
//UniformSample is a metric sample
type UniformSample struct {
count int64
mutex sync.Mutex
reservoirSize int
values []int64
}
// NewUniformSample constructs a new uniform sample with the given reservoir
// size.
func NewUniformSample(reservoirSize int) metrics.Sample {
return &UniformSample{
reservoirSize: reservoirSize,
values: make([]int64, 0, reservoirSize),
}
}
// Clear clears all samples.
func (s *UniformSample) Clear() {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count = 0
s.values = make([]int64, 0, s.reservoirSize)
}
// Count returns the number of samples recorded, which may exceed the
// reservoir size.
func (s *UniformSample) Count() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return s.count
}
// Max returns the maximum value in the sample, which may not be the maximum
// value ever to be part of the sample.
func (s *UniformSample) Max() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleMax(s.values)
}
// Mean returns the mean of the values in the sample.
func (s *UniformSample) Mean() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleMean(s.values)
}
// Min returns the minimum value in the sample, which may not be the minimum
// value ever to be part of the sample.
func (s *UniformSample) Min() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleMin(s.values)
}
// Percentile returns an arbitrary percentile of values in the sample.
func (s *UniformSample) Percentile(p float64) float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SamplePercentile(s.values, p)
}
// Percentiles returns a slice of arbitrary percentiles of values in the
// sample.
func (s *UniformSample) Percentiles(ps []float64) []float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SamplePercentiles(s.values, ps)
}
// Size returns the size of the sample, which is at most the reservoir size.
func (s *UniformSample) Size() int {
s.mutex.Lock()
defer s.mutex.Unlock()
return len(s.values)
}
// Snapshot returns a read-only copy of the sample.
func (s *UniformSample) Snapshot() metrics.Sample {
s.mutex.Lock()
defer s.mutex.Unlock()
values := make([]int64, len(s.values))
copy(values, s.values)
return metrics.NewSampleSnapshot(s.count, values)
}
// StdDev returns the standard deviation of the values in the sample.
func (s *UniformSample) StdDev() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleStdDev(s.values)
}
// Sum returns the sum of the values in the sample.
func (s *UniformSample) Sum() int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleSum(s.values)
}
// Update samples a new value.
func (s *UniformSample) Update(v int64) {
s.mutex.Lock()
defer s.mutex.Unlock()
s.count++
if len(s.values) < s.reservoirSize {
s.values = append(s.values, v)
} else {
// Use circle buffer to eliminate the oldest value
idx := s.count % int64(s.reservoirSize)
s.values[idx] = v
}
}
// Values returns a copy of the values in the sample.
func (s *UniformSample) Values() []int64 {
s.mutex.Lock()
defer s.mutex.Unlock()
values := make([]int64, len(s.values))
copy(values, s.values)
return values
}
// Variance returns the variance of the values in the sample.
func (s *UniformSample) Variance() float64 {
s.mutex.Lock()
defer s.mutex.Unlock()
return metrics.SampleVariance(s.values)
}