Method resolveRemotes

core/remote_join.go:58–196

resolveRemotes fetches remote data for the marked insertion points

(
	ctx context.Context,
	from []jsn.Field,
	sfmap map[string]*qcode.Select,
	cursorFields map[string]struct{},
)

// resolveRemotes fetches remote data for the marked insertion points
func (s *gstate) resolveRemotes(
	ctx context.Context,
	from []jsn.Field,
	sfmap map[string]*qcode.Select,
	cursorFields map[string]struct{},
) ([]jsn.Field, map[string]json.RawMessage, error) {
	selects := s.cs.st.qc.Selects

	// replacement data for the marked insertion points
	// key and value will be replaced by whats below
	to := make([]jsn.Field, len(from))
	extra := make(map[string]json.RawMessage)
	var extraMutex sync.Mutex

	var wg sync.WaitGroup
	wg.Add(len(from))

	var cerr error
	var cerrMutex sync.Mutex

	for i, id := range from {
		// use the json key to find the related Select object
		sel, ok := sfmap[string(id.Key)]
		if !ok {
			return nil, nil, fmt.Errorf("invalid remote field key")
		}

		// Lookup the resolver. Top-level remotes (ParentID == -1) are
		// keyed by table name alone; row-joins are keyed by table+parent.
		var (
			r    resItem
			rid  []byte
			rkey string
		)
		if sel.ParentID == -1 {
			rkey = sel.Table
			r, ok = s.gj.rmap[rkey]
		} else {
			p := selects[sel.ParentID]
			rkey = sel.Table + p.Table
			r, ok = s.gj.rmap[rkey]
			if ok {
				rid = jsn.Value(id.Value)
				if len(rid) == 0 {
					return nil, nil, fmt.Errorf("invalid remote field id")
				}
			}
		}
		if !ok {
			return nil, nil, fmt.Errorf("no resolver found for remote %q", rkey)
		}

		go func(n int, id []byte, sel *qcode.Select, r resItem, rkey string) {
			defer wg.Done()

			ctx1, span := s.gj.spanStart(ctx, "Execute Remote Request")
			defer span.End()