}

// MonitorReaderOptions provides configurable options for monitor reader implementation.
type MonitorReaderOptions struct {
	BucketOptions
	HeaderSize int
}

// Read implements a throttled read
func (r *MonitoredReader) Read(buf []byte) (n int, err error) {
	if r.throttle == nil {
		return r.r.Read(buf)
	}
	if r.lastErr != nil {
		err = r.lastErr
		return
	}

	columnNames  []string         // names of columns
	nameIndexMap map[string]int64 // name to column index
	current      [][]string       // current block of results to be returned
	recordsRead  int              // number of records read in current slice
	input        chan *queueItem  // input for workers
	queue        chan *queueItem  // output from workers in order

		return nil
	}

	r.contentHasher = cs.Type.Hasher()
	if r.contentHasher == nil {
		return ErrInvalidChecksum
	}
	return nil
}

func (r *Reader) Read(p []byte) (int, error) {
	n, err := r.src.Read(p)
	r.bytesRead += int64(n)
	if r.sha256 != nil {
		r.sha256.Write(p[:n])
	}
	if r.contentHasher != nil {
		r.contentHasher.Write(p[:n])
	}

// Write -  implement hash.Hash Write
func (u UUIDHash) Write(p []byte) (n int, err error) {
	return len(p), nil
}

// Sum -  implement md5.Sum
func (u UUIDHash) Sum(b []byte) []byte {
	return u.uuid
}

// Reset -  implement hash.Hash Reset
func (u UUIDHash) Reset() {
	return
}

// Size -  implement hash.Hash Size
func (u UUIDHash) Size() int {
	return len(u.uuid)
}

// safeCloser will wrap a Reader as a ReadCloser.
// It is safe to call Close while the reader is being used.
type safeCloser struct {
	closed uint32
	r      io.Reader
}

func (s *safeCloser) Read(p []byte) (n int, err error) {
	if atomic.LoadUint32(&s.closed) == 1 {
		return 0, io.EOF
	}
	n, err = s.r.Read(p)
	if atomic.LoadUint32(&s.closed) == 1 {
		return 0, io.EOF
	}
	return n, err
}