go - Prometheus Go 客户端库的 ExponentialBuckets API 的最低粒度是多少？

Question

我正在试验 Prometheus Go client library .是否ExponentialBuckets API接受小于 1.0(例如 0.001)的参数 start？

Answer 1

package prometheus

import "github.com/prometheus/client_golang/prometheus"

func ExponentialBuckets

func ExponentialBuckets(start, factor float64, count int) []float64

ExponentialBuckets creates 'count' buckets, where the lowest bucket has an upper bound of 'start' and each following bucket's upper bound is 'factor' times the previous bucket's upper bound. The final +Inf bucket is not counted and not included in the returned slice. The returned slice is meant to be used for the Buckets field of HistogramOpts.

The function panics if 'count' is 0 or negative, if 'start' is 0 or negative, or if 'factor' is less than or equal 1.

---

尝试start等于最小正常正数float64。

package main

import (
    "fmt"
    "math"
)

func main() {
    // Minimum normal positive float64
    // 0 00000000001 0000000000000000000000000000000000000000000000000000
    // 2.2250738585072014e−308
    start := math.Float64frombits(uint64(1 << (63 - 11)))
    fmt.Println(start)
}

输出:

2.2250738585072014e-308