golang histogram 代码
文件路径：/src/runtime/metrics/histogram.go
/ Copyright 2020 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package metrics
/ Float64Histogram represents a distribution of float64 values.
type Float64Histogram struct {
/ Counts contains the weights for each histogram bucket.
/
/ Given N buckets, Count[n] is the weight of the range
/ [bucket[n], bucket[n+1]), for 0 <= n < N.
Counts []uint64
/ Buckets contains the boundaries of the histogram buckets, in increasing order.
/
/ Buckets[0] is the inclusive lower bound of the minimum bucket while
/ Buckets[len(Buckets)-1] is the exclusive upper bound of the maximum bucket.
/ Hence, there are len(Buckets)-1 counts. Furthermore, len(Buckets) != 1, always,
/ since at least two boundaries are required to describe one bucket (and 0
/ boundaries are used to describe 0 buckets).
/
/ Buckets[0] is permitted to have value -Inf and Buckets[len(Buckets)-1] is
/ permitted to have value Inf.
/
/ For a given metric name, the value of Buckets is guaranteed not to change
/ between calls until program exit.
/
/ This slice value is permitted to alias with other Float64Histograms' Buckets
/ fields, so the values within should only ever be read. If they need to be
/ modified, the user must make a copy.
Buckets []float64
}