Function SendHeader

server.go:2121–2130

SendHeader sends header metadata. It may be called at most once, and may not be called after any event that causes headers to be sent (see SetHeader for a complete list). The provided md and headers set by SetHeader() will be sent. The error returned is compatible with the status package. However

(ctx context.Context, md metadata.MD)

// status code will often not match the RPC status as seen by the client
// application, and therefore, should not be relied upon for this purpose.
func SendHeader(ctx context.Context, md metadata.MD) error {
	stream := ServerTransportStreamFromContext(ctx)
	if stream == nil {
		return status.Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
	}
	if err := stream.SendHeader(md); err != nil {
		return toRPCErr(err)
	}
	return nil
}

// SetSendCompressor sets a compressor for outbound messages from the server.
// It must not be called after any event that causes headers to be sent