Connection multiplexer reuse

[coyzeng]

  @override
  Future<Uint8List> consume(
      Context ctx, String urn, Execution exec, Uint8List inbound) async {
    try {
      final uri = ctx.getAttribute(addressKey);
      final chan = chans.putIfAbsent(uri, () => create(uri));
      final method = ClientMethod<Uint8List, Uint8List>('/mpc/grpc', (v) {
        return v;
      }, (v) {
        return Uint8List.fromList(v);
      });
      final option = CallOptions(timeout: exec.schema().timeout, metadata: {});
      final call = chan.createCall<Uint8List, Uint8List>(
          method, Stream.value(inbound), option);
      return await call.response.first;
    } catch (e) {
      if (e is GrpcError) {
        switch (e.code) {
          case StatusCode.aborted:
          case StatusCode.cancelled:
          case StatusCode.unknown:
          case StatusCode.internal:
          case StatusCode.alreadyExists:
            throw Status.system.err(r: e.toString());
          case StatusCode.invalidArgument:
          case StatusCode.dataLoss:
            throw Status.validate.err(r: e.toString());
          case StatusCode.deadlineExceeded:
            throw Status.timeout.err(r: e.toString());
          case StatusCode.unavailable:
            throw Status.netUnavailable.err(r: e.toString());
          case StatusCode.notFound:
          case StatusCode.unimplemented:
            throw Status.notfound.err(r: e.toString());
          case StatusCode.outOfRange:
          case StatusCode.resourceExhausted:
          case StatusCode.unauthenticated:
          case StatusCode.permissionDenied:
          case StatusCode.failedPrecondition:
            throw Status.unauthorized.err(r: e.toString());
        }
      }
      rethrow;
    }
  }

 final call = chan.createCall<Uint8List, Uint8List>(
          method, Stream.value(inbound), option);
      return await call.response.first;

Code above will disconnect connection when some requests response. It can not reuse too many times. How to reuse connections gracefully?