golf.go

package main

import (
	"fmt"
	"io"
	"os"
	"strings"
	"time"
)

func main() {
	timer := time.NewTimer(0)
	timer.Stop() // don't let the timer fire yet

	go func() {
		last := time.Now()
		for ts := range timer.C {
			fmt.Fprintf(os.Stderr,
				"%s %s %s\n",
				ts.Format(time.RFC3339),
				ts.Sub(last).Truncate(100*time.Millisecond),
				strings.Repeat("-", 20),
			)
			last = ts
		}
	}()
	
	io.Copy(
		writeFunc(func(p []byte) (int, error) {
			timer.Reset(3 * time.Second)
			return os.Stdout.Write(p)
		}),
		os.Stdin,
	)
}

type writeFunc func(p []byte) (int, error)

func (wf writeFunc) Write(p []byte) (int, error) { return wf(p) }