Dont request more data until the first message is received

src/core/surface/call.c

@@ -118,6 +118,7 @@ struct grpc_call {
   gpr_uint8 got_status_code;
   gpr_uint8 sending;
   gpr_uint8 num_completed_requests;
+  gpr_uint8 got_any_data;
   gpr_uint8 need_more_data;
 
   reqinfo requests[GRPC_IOREQ_OP_COUNT];
@@ -575,7 +576,7 @@ static grpc_call_error start_ioreq(grpc_call *call, const grpc_ioreq *reqs,
                call->buffered_messages);
           finish_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGES, GRPC_OP_OK);
         } else {
-          call->need_more_data = 1;
+          call->need_more_data = call->got_any_data;
         }
         if (call->stream_closed) {
           finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS, GRPC_OP_OK);
@@ -1053,6 +1054,7 @@ void grpc_call_recv_message(grpc_call_element *elem,
   grpc_call *call = CALL_FROM_TOP_ELEM(elem);
   grpc_byte_buffer_array *dest;
   lock(call);
+  call->got_any_data = 1;
   if (call->requests[GRPC_IOREQ_RECV_MESSAGES].master != NULL) {
     dest = call->requests[GRPC_IOREQ_RECV_MESSAGES].data.recv_messages;
   } else {