Method AddResponse

modules/frontend/combiner/common.go:65–146

AddResponse is used to add a http response to the combiner.

(r PipelineResponse)

// AddResponse is used to add a http response to the combiner.
func (c *genericCombiner[T]) AddResponse(r PipelineResponse) error {
	if r.IsMetadata() && c.metadata != nil {
		c.mu.Lock()
		defer c.mu.Unlock()

		if err := c.metadata(r, c.current); err != nil {
			return fmt.Errorf("error processing metadata: %w", err)
		}
		return nil
	}

	res := r.HTTPResponse()
	if res == nil {
		return nil
	}

	// todo: reevaluate this. should the caller owner the lifecycle of the http.response body?
	defer func() { _ = res.Body.Close() }()

	// test shouldQuit and set response all under the same lock. this prevents race conditions where
	// two responses can make it pass shouldQuit() with different results.
	shouldQuitAndSetResponse := func() (bool, error) {
		c.mu.Lock()
		defer c.mu.Unlock()

		if c.shouldQuit() {
			return true, nil
		}

		if res.StatusCode != http.StatusOK {
			bytesMsg, err := io.ReadAll(res.Body)
			if err != nil {
				return true, fmt.Errorf("error reading response body: %w", err)
			}
			c.httpRespBody = string(bytesMsg)
			c.httpStatusCode = res.StatusCode
			// don't return error. the error path is reserved for unexpected errors.
			// http pipeline errors should be returned through the final response. (Complete/TypedComplete/TypedDiff)
			return true, nil
		}

		return false, nil
	}

	if quit, err := shouldQuitAndSetResponse(); quit {
		return err
	}

	partial := c.new() // instantiating directly requires additional type constraints. this seemed cleaner: https://stackoverflow.com/questions/69573113/how-can-i-instantiate-a-non-nil-pointer-of-type-argument-with-generic-go

	switch res.Header.Get(api.HeaderContentType) {
	case api.HeaderAcceptProtobuf:
		b, err := tempo_io.ReadAllWithEstimate(res.Body, res.ContentLength)
		if err != nil {
			return fmt.Errorf("error reading response body")
		}
		if err := proto.Unmarshal(b, partial); err != nil {
			return fmt.Errorf("error unmarshalling proto response body: %w", err)