time.Duration类型的微秒值转换为毫秒

Question

I am using go-ping ( https://github.com/sparrc/go-ping )library of golang for unprivileged ICMP ping.

timeout := time.Second*1000
interval := time.Second
count := 5
host := p.ipAddr
pinger, cmdErr := ping.NewPinger(host)

pinger.Count = count
pinger.Interval = interval
pinger.Timeout = timeout
pinger.SetPrivileged(false)
pinger.Run()
stats := pinger.Statistics()

latency = stats.AvgRtt  // stats.AvgRtt is time.Duration type
jitter = stats.StdDevRtt// stats.StdDevRtt is time.Duration type

From running this, I am getting latency in milliseconds and jitter in microseconds. I want same unit for both let's say millisecond so when I am doing jitter = stats.StdDevRtt/1000 or jitter = jitter/1000 (to convert microseconds to milliseconds), what I am getting is jitter in nanoseconds :(. Is there any way to get same unit milliseconds for both latency and jitter.

Answer 1

Number to time.Duration

time.Duration is a type having int64 as its underlying type, which stores the duration in nanoseconds.

If you know the value but you want other than nanoseconds, simply multiply the unit you want, e.g.:

d := 100 * time.Microsecond
fmt.Println(d) // Output: 100µs

The above works because 100 is an untyped constant, and it can be converted automatically to time.Duration which has int64 underlying type.

Note that if you have the value as a typed value, you have to use explicit type conversion:

value := 100 // value is of type int

d2 := time.Duration(value) * time.Millisecond
fmt.Println(d2) // Output: 100ms

time.Duration to number

So time.Duration is always the nanoseconds. If you need it in milliseconds for example, all you need to do is divide the time.Duration value with the number of nanoseconds in a millisecond:

ms := int64(d2 / time.Millisecond)
fmt.Println("ms:", ms) // Output: ms: 100

Other examples:

fmt.Println("ns:", int64(d2/time.Nanosecond))  // ns: 100000000
fmt.Println("µs:", int64(d2/time.Microsecond)) // µs: 100000
fmt.Println("ms:", int64(d2/time.Millisecond)) // ms: 100

Try the examples on the Go Playground.

If your jitter (duration) is less than the unit you whish to convert it to, you need to use floating point division, else an integer division will be performed which cuts off the fraction part. For details see: Golang Round to Nearest 0.05.

Convert both the jitter and unit to float64 before dividing:

d := 61 * time.Microsecond
fmt.Println(d) // Output: 61µs

ms := float64(d) / float64(time.Millisecond)
fmt.Println("ms:", ms) // Output: ms: 0.061

Output (try it on the Go Playground):

61µs
ms: 0.061