// Slice sharing problem.

package main

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"strings"
	"time"
)

func consumer(ctx context.Context, in <-chan []byte) {
	for {
		select {
		case <-ctx.Done():
			return
		case data := <-in:
			fmt.Printf("%#v\n", string(data))
		}
	}
}

func produce(reader io.Reader, out chan<- []byte) {
	var buf [4]byte
	for {
		n, err := reader.Read(buf[:])
		if err != nil {
			break
		}
		if n > 0 {
			if strings.Trim(string(buf[:n]), " \r\n\t") == "quit" {
				break
			}
			out <- buf[:n]
		}
	}
}

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	const data = "1234567890abcdef"
	ch := make(chan []byte)
	go consumer(ctx, ch)
	produce(bytes.NewReader([]byte(data)), ch)
	time.Sleep(16 * time.Millisecond)
}