zioutil/slow_copy.go

package zioutil

import (
	"io"
	"sync"
)

func SlowCopy(w io.Writer, r io.Reader, stepsize int) (n int, err error) {
	rbuf := make([]byte, stepsize)
	cnt := 0
	for {
		n, err := r.Read(rbuf)
		if n == 0 {
			continue
		}
		if err != nil {
			return cnt, err
		}
		n, err = w.Write(rbuf)
		if err != nil {
			return cnt, err
		}
		cnt += n
	}
}

func SlowBidiCopy(rw1, rw2 io.ReadWriter, stepsize12, stepsize21 int) (n12, n21 int, err12, err21 error) {
	wg := sync.WaitGroup{}
	wg.Add(2)
	go func() {
		n12, err12 = SlowCopy(rw2, rw1, stepsize12)
		wg.Done()
	}()
	go func() {
		n21, err21 = SlowCopy(rw1, rw2, stepsize21)
		wg.Done()
	}()
	wg.Wait()
	return
}