Non-blocking reader for Go. Probably a bad idea.

nonblocking.go

package nonblocking

import (
	"io"
	"time"
)

type NonBlockingReader struct {
	ch  chan []byte
	rd  io.Reader
	err error
}

func NewNonBlockingReader(r io.Reader) *NonBlockingReader {
	nbr := &NonBlockingReader{
		ch: make(chan []byte),
		rd: r,
	}
	go nbr.pipe()
	return nbr
}

func (nbr *NonBlockingReader) pipe() {
	d1 := make([]byte, 1024)
	d2 := make([]byte, 1024)
	for {
		n, err := nbr.rd.Read(d1)
		if n > 0 {
			nbr.ch <- d1[:n]
			d1, d2 = d2, d1
		}
		if err != nil {
			nbr.err = err
			close(nbr.ch)
			break
		}
	}
}

func (nbr *NonBlockingReader) Read(p []byte) (n int, err error) {
	// TODO: Empty channel completely?
	select {
	case d := <-nbr.ch:
		if len(d) > len(p) {
			// TODO: Buffer data
			panic("NonBlockingReader: couldn't fit data")
		}
		n = copy(p, d)
		return
	case <-time.After(1 * time.Millisecond):
		return 0, nbr.err
	}
}