1// Copyright 2020 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package metrics
6
7// Float64Histogram represents a distribution of float64 values.
8type Float64Histogram struct {
9	// Counts contains the weights for each histogram bucket.
10	//
11	// Given N buckets, Count[n] is the weight of the range
12	// [bucket[n], bucket[n+1]), for 0 <= n < N.
13	Counts []uint64
14
15	// Buckets contains the boundaries of the histogram buckets, in increasing order.
16	//
17	// Buckets[0] is the inclusive lower bound of the minimum bucket while
18	// Buckets[len(Buckets)-1] is the exclusive upper bound of the maximum bucket.
19	// Hence, there are len(Buckets)-1 counts. Furthermore, len(Buckets) != 1, always,
20	// since at least two boundaries are required to describe one bucket (and 0
21	// boundaries are used to describe 0 buckets).
22	//
23	// Buckets[0] is permitted to have value -Inf and Buckets[len(Buckets)-1] is
24	// permitted to have value Inf.
25	//
26	// For a given metric name, the value of Buckets is guaranteed not to change
27	// between calls until program exit.
28	//
29	// This slice value is permitted to alias with other Float64Histograms' Buckets
30	// fields, so the values within should only ever be read. If they need to be
31	// modified, the user must make a copy.
32	Buckets []float64
33}
34