Is there an efficient way to calculate execution time in golang?

Issue

I’m looking for the best way to calculate execution time in go.

func main() {
    start := time.Now()

    time.Sleep(time.Second * 2)

    //something doing here

    elapsed := time.Since(start)
    fmt.Printf("page took %s", elapsed)
}

The code above works fine.

But when I use templates, I have to write it again for each template function.

Is there an efficient way of calculating execution time, including templates?

Solution

If you are timing an entire function, then you can use defer to eliminate some of the repetitive code.

func elapsed(what string) func() {
    start := time.Now()
    return func() {
        fmt.Printf("%s took %v\n", what, time.Since(start))
    }
}

func main() {
    defer elapsed("page")()  // <-- The trailing () is the deferred call
    time.Sleep(time.Second * 2)
}

playground example

The specification says this about deferred calls:

Each time a "defer" statement executes, the function value and parameters to the call are evaluated as usual and saved anew but the actual function is not invoked. Instead, deferred functions are invoked immediately before the surrounding function returns,

The function value elapsed("page") is evaluated at the defer statement. The elapsed function records the current time and returns an anonymous function. The returned anonymous function is invoked immediately before the surrounding function returns. The anonymous function computes and prints the elapsed time.

Answered By – Bayta Darell

Answer Checked By – David Goodson (GoLangFix Volunteer)