we don't need cancelable reader

go/store/nbs/s3_table_reader.go

@@ -178,7 +178,6 @@ func (s3or *s3ObjectReader) readRange(ctx context.Context, name addr, p []byte,
 				}
 			}
 		}
-		//cancelableReader := NewCancelableReader(ctx, result.Body)
 		n, err = io.ReadFull(result.Body, p)
 		return n, sz, err
 	}
@@ -210,53 +209,3 @@ func isConnReset(err error) bool {
 	scErr, ok := nErr.Err.(*os.SyscallError)
 	return ok && scErr.Err == syscall.ECONNRESET
 }
-
-type CancelableReader struct {
-	ctx  context.Context
-	data chan []byte
-	err  error
-	r    io.Reader
-}
-
-func (c *CancelableReader) begin() {
-	buf := make([]byte, 1024)
-	for {
-		if c.ctx.Err() != nil {
-			return
-		}
-		n, err := c.r.Read(buf)
-		if n > 0 {
-			tmp := make([]byte, n)
-			copy(tmp, buf[:n])
-			c.data <- tmp
-		}
-		if err != nil {
-			c.err = err
-			close(c.data)
-			return
-		}
-	}
-}
-
-func (c *CancelableReader) Read(p []byte) (int, error) {
-	select {
-	case <-c.ctx.Done():
-		return 0, c.ctx.Err()
-	case d, ok := <-c.data:
-		if !ok {
-			return 0, c.err
-		}
-		copy(p, d)
-		return len(d), nil
-	}
-}
-
-func NewCancelableReader(ctx context.Context, r io.Reader) *CancelableReader {
-	c := &CancelableReader{
-		r:    r,
-		ctx:  ctx,
-		data: make(chan []byte),
-	}
-	go c.begin()
-	return c
-}