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histogram.go
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histogram.go
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package metrics
// Histograms calculate distribution statistics from a series of int64 values.
type Histogram interface {
Clear()
Count() int64
Max() int64
Mean() float64
Min() int64
Percentile(float64) float64
Percentiles([]float64) []float64
Sample() Sample
Snapshot() Histogram
StdDev() float64
Sum() int64
Update(int64)
Variance() float64
}
// GetOrRegisterHistogram returns an existing Histogram or constructs and
// registers a new StandardHistogram.
func GetOrRegisterHistogram(name string, r Registry, s Sample) Histogram {
if nil == r {
r = DefaultRegistry
}
return r.GetOrRegister(name, func() Histogram { return NewHistogram(s) }).(Histogram)
}
// NewHistogram constructs a new StandardHistogram from a Sample.
func NewHistogram(s Sample) Histogram {
if UseNilMetrics {
return NilHistogram{}
}
return &StandardHistogram{sample: s}
}
// NewRegisteredHistogram constructs and registers a new StandardHistogram from
// a Sample.
func NewRegisteredHistogram(name string, r Registry, s Sample) Histogram {
c := NewHistogram(s)
if nil == r {
r = DefaultRegistry
}
r.Register(name, c)
return c
}
// HistogramSnapshot is a read-only copy of another Histogram.
type HistogramSnapshot struct {
sample *SampleSnapshot
}
// Clear panics.
func (*HistogramSnapshot) Clear() {
panic("Clear called on a HistogramSnapshot")
}
// Count returns the number of samples recorded at the time the snapshot was
// taken.
func (h *HistogramSnapshot) Count() int64 { return h.sample.Count() }
// Max returns the maximum value in the sample at the time the snapshot was
// taken.
func (h *HistogramSnapshot) Max() int64 { return h.sample.Max() }
// Mean returns the mean of the values in the sample at the time the snapshot
// was taken.
func (h *HistogramSnapshot) Mean() float64 { return h.sample.Mean() }
// Min returns the minimum value in the sample at the time the snapshot was
// taken.
func (h *HistogramSnapshot) Min() int64 { return h.sample.Min() }
// Percentile returns an arbitrary percentile of values in the sample at the
// time the snapshot was taken.
func (h *HistogramSnapshot) Percentile(p float64) float64 {
return h.sample.Percentile(p)
}
// Percentiles returns a slice of arbitrary percentiles of values in the sample
// at the time the snapshot was taken.
func (h *HistogramSnapshot) Percentiles(ps []float64) []float64 {
return h.sample.Percentiles(ps)
}
// Sample returns the Sample underlying the histogram.
func (h *HistogramSnapshot) Sample() Sample { return h.sample }
// Snapshot returns the snapshot.
func (h *HistogramSnapshot) Snapshot() Histogram { return h }
// StdDev returns the standard deviation of the values in the sample at the
// time the snapshot was taken.
func (h *HistogramSnapshot) StdDev() float64 { return h.sample.StdDev() }
// Sum returns the sum in the sample at the time the snapshot was taken.
func (h *HistogramSnapshot) Sum() int64 { return h.sample.Sum() }
// Update panics.
func (*HistogramSnapshot) Update(int64) {
panic("Update called on a HistogramSnapshot")
}
// Variance returns the variance of inputs at the time the snapshot was taken.
func (h *HistogramSnapshot) Variance() float64 { return h.sample.Variance() }
// NilHistogram is a no-op Histogram.
type NilHistogram struct{}
// Clear is a no-op.
func (NilHistogram) Clear() {}
// Count is a no-op.
func (NilHistogram) Count() int64 { return 0 }
// Max is a no-op.
func (NilHistogram) Max() int64 { return 0 }
// Mean is a no-op.
func (NilHistogram) Mean() float64 { return 0.0 }
// Min is a no-op.
func (NilHistogram) Min() int64 { return 0 }
// Percentile is a no-op.
func (NilHistogram) Percentile(p float64) float64 { return 0.0 }
// Percentiles is a no-op.
func (NilHistogram) Percentiles(ps []float64) []float64 {
return make([]float64, len(ps))
}
// Sample is a no-op.
func (NilHistogram) Sample() Sample { return NilSample{} }
// Snapshot is a no-op.
func (NilHistogram) Snapshot() Histogram { return NilHistogram{} }
// StdDev is a no-op.
func (NilHistogram) StdDev() float64 { return 0.0 }
// Sum is a no-op.
func (NilHistogram) Sum() int64 { return 0 }
// Update is a no-op.
func (NilHistogram) Update(v int64) {}
// Variance is a no-op.
func (NilHistogram) Variance() float64 { return 0.0 }
// StandardHistogram is the standard implementation of a Histogram and uses a
// Sample to bound its memory use.
type StandardHistogram struct {
sample Sample
}
// Clear clears the histogram and its sample.
func (h *StandardHistogram) Clear() { h.sample.Clear() }
// Count returns the number of samples recorded since the histogram was last
// cleared.
func (h *StandardHistogram) Count() int64 { return h.sample.Count() }
// Max returns the maximum value in the sample.
func (h *StandardHistogram) Max() int64 { return h.sample.Max() }
// Mean returns the mean of the values in the sample.
func (h *StandardHistogram) Mean() float64 { return h.sample.Mean() }
// Min returns the minimum value in the sample.
func (h *StandardHistogram) Min() int64 { return h.sample.Min() }
// Percentile returns an arbitrary percentile of the values in the sample.
func (h *StandardHistogram) Percentile(p float64) float64 {
return h.sample.Percentile(p)
}
// Percentiles returns a slice of arbitrary percentiles of the values in the
// sample.
func (h *StandardHistogram) Percentiles(ps []float64) []float64 {
return h.sample.Percentiles(ps)
}
// Sample returns the Sample underlying the histogram.
func (h *StandardHistogram) Sample() Sample { return h.sample }
// Snapshot returns a read-only copy of the histogram.
func (h *StandardHistogram) Snapshot() Histogram {
return &HistogramSnapshot{sample: h.sample.Snapshot().(*SampleSnapshot)}
}
// StdDev returns the standard deviation of the values in the sample.
func (h *StandardHistogram) StdDev() float64 { return h.sample.StdDev() }
// Sum returns the sum in the sample.
func (h *StandardHistogram) Sum() int64 { return h.sample.Sum() }
// Update samples a new value.
func (h *StandardHistogram) Update(v int64) { h.sample.Update(v) }
// Variance returns the variance of the values in the sample.
func (h *StandardHistogram) Variance() float64 { return h.sample.Variance() }