import okio.Source
import okio.Timeout

/**
 * Replicates a single upstream source into multiple downstream sources. Each downstream source
 * returns the same bytes as the upstream source. Downstream sources may read data either as it
 * is returned by upstream, or after the upstream source has been exhausted.
 *
 * As bytes are returned from upstream they are written to a local file. Downstream sources read
 * from this file as necessary.

					// bucketResults channel while the
					// updates-collector goroutine still
					// holds a reference to this.
					wg.Wait()
					continue
				}

				wg.Wait()
				// Flatten for upstream, but save full state.
				var root dataUsageEntry
				if r := cache.root(); r != nil {
					root = cache.flatten(*r)
				}
				select {
				case <-ctx.Done():
					return

				return
			} else if rec != nil {
				stack := debug.Stack()
				logger.Error("panic: \"%s %s\": %v\n%s", r.Method, r.URL, rec, string(stack))
				// Try to write an error response, upstream may not have written header.
				writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrInternalError), r.URL)
				return
			}
		}()
		h.ServeHTTP(w, r)
	})
}

			select {
			case <-ctx.Done():
			case updates <- *resp.Update:
			}
		}
		if resp.Final != nil {
			final = resp.Final
		}
		// We can't reuse the response since it is sent upstream.
		return nil
	})
	if err != nil {
		return cache, toStorageErr(err)
	}
	if final == nil {
		return cache, errors.New("no final cache")
	}
	return *final, nil
}

## Version 4.3.0

_2019-12-31_

 *  Fix: Degrade HTTP/2 connections after a timeout. When an HTTP/2 stream times out it may impact
    the stream only or the entire connection. With this fix OkHttp will now send HTTP/2 pings after
    a stream timeout to determine whether the connection should remain eligible for pooling.

func listPathRaw(ctx context.Context, opts listPathRawOptions) (err error) {
	disks := opts.disks
	if len(disks) == 0 {
		return fmt.Errorf("listPathRaw: 0 drives provided")
	}

	// Cancel upstream if we finish before we expect.
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	// Keep track of fallback disks
	var fdMu sync.Mutex
	fds := opts.fallbackDisks

	case authTypeStreamingSigned, authTypeStreamingSignedTrailer:
		// Initialize stream signature verifier.
		reader, s3Error = newSignV4ChunkedReader(r, rAuthType == authTypeStreamingSignedTrailer)
		if s3Error != ErrNone {
			writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
			return
		}
	case authTypeStreamingUnsignedTrailer:
		// Initialize stream signature verifier.

	if err != nil {
		return encryptedETag
	}
	return hex.EncodeToString(etagBytes)
}

// GetDecryptedRange - To decrypt the range (off, length) of the
// decrypted object stream, we need to read the range (encOff,
// encLength) of the encrypted object stream to decrypt it, and
// compute skipLen, the number of bytes to skip in the beginning of
// the encrypted range.
//
// In addition we also compute the object part number for where the

// Note that upstream errors are currently not forwarded, but may be in the future.
func (h *httpStreamResponse) Write(b []byte) (int, error) {
	if len(b) == 0 || h.err != nil {
		// Ignore 0 length blocks
		return 0, h.err
	}
	tmp := make([]byte, len(b))
	copy(tmp, b)
	h.block <- tmp
	return len(b), h.err
}

// CloseWithError will close the stream and return the specified error.

	return s.newCache, nil
}

// sendUpdate() should be called on a regular basis when the newCache contains more recent total than previously.
// May or may not send an update upstream.
func (f *folderScanner) sendUpdate() {
	// Send at most an update every minute.
	if f.updates == nil || time.Since(f.lastUpdate) < time.Minute {
		return
	}