p.readerToBuf[i] = next
		next++
	}
}

// Returns if buf can be erasure decoded.
func (p *parallelReader) canDecode(buf [][]byte) bool {
	bufCount := 0
	for _, b := range buf {
		if len(b) > 0 {
			bufCount++
		}
	}
	return bufCount >= p.dataBlocks
}

// Read reads from readers in parallel. Returns p.dataBlocks number of bufs.
func (p *parallelReader) Read(dst [][]byte) ([][]byte, error) {