Function GetSchemaOverNetwork

worker/schema.go:182–223

GetSchemaOverNetwork checks which group should be serving the schema according to fingerprint of the predicate and sends it to that instance.

(ctx context.Context, schema *pb.SchemaRequest)

// GetSchemaOverNetwork checks which group should be serving the schema
// according to fingerprint of the predicate and sends it to that instance.
func GetSchemaOverNetwork(ctx context.Context, schema *pb.SchemaRequest) (
	[]*pb.SchemaNode, error) {

	ctx, span := otel.Tracer("").Start(ctx, "worker.GetSchemaOverNetwork")
	defer span.End()

	// There was a health check here which is not needed. The health check should be done by the
	// receiver of the request, not the sender.

	if len(schema.Predicates) == 0 && len(schema.Types) > 0 {
		return nil, nil
	}

	// Map of groupd id => Predicates for that group.
	schemaMap := make(map[uint32]*pb.SchemaRequest)
	if err := addToSchemaMap(schemaMap, schema); err != nil {
		return nil, err
	}

	results := make(chan resultErr, len(schemaMap))
	var schemaNodes []*pb.SchemaNode

	for gid, s := range schemaMap {
		go getSchemaOverNetwork(ctx, gid, s, results)
	}

	// wait for all the goroutines to reply back.
	// we return if an error was returned or the parent called ctx.Done()
	for range schemaMap {
		select {
		case r := <-results:
			if r.err != nil {
				return nil, r.err
			}
			schemaNodes = append(schemaNodes, r.result.Schema...)
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}

	return schemaNodes, nil
}

// Schema is used to get schema information over the network on other instances.
func (w *grpcWorker) Schema(ctx context.Context, s *pb.SchemaRequest) (*pb.SchemaResult, error) {