diff --git a/Makefile b/Makefile
index 124c569..1dfcbfe 100644
--- a/Makefile
+++ b/Makefile
@@ -104,6 +104,6 @@ test: $(TEST)
 
 af:
 	@mkdir -p cmake_build
-	@cd cmake_build; cmake .. -DCMAKE_CUDA_COMPILER=$(CMAKE_CUDA_COMPILER) -DPython_EXECUTABLE=/usr/bin/python3 -DCUDA_TOOLKIT_ROOT_DIR=$(CUDA_TOOLKIT_ROOT_DIR); make -j
+	@cd cmake_build; cmake .. -DCMAKE_CUDA_COMPILER=$(CMAKE_CUDA_COMPILER) -DPython_EXECUTABLE=$(shell which python3) -DCUDA_TOOLKIT_ROOT_DIR=$(CUDA_TOOLKIT_ROOT_DIR); make -j
 	@mkdir -p build
 
diff --git a/fserver/csrc/private.hpp b/fserver/csrc/private.hpp
index aa3e668..816563d 100644
--- a/fserver/csrc/private.hpp
+++ b/fserver/csrc/private.hpp
@@ -13,9 +13,72 @@
 
 using namespace ps;
 #ifdef DMLC_USE_CUDA
-void pybind_private(py::module &m){}
+class SimpleNotify{
+private:
+    int notify_cnt = 1;
+    CUdeviceptr dflag;
+    uint32_t* hflag;
+    std::thread th_;
+    std::future<std::vector<ServerDataBatch>> fut;
+public:
+    void init() {
+        cudaHostAlloc(&hflag, sizeof(uint32_t), cudaHostAllocMapped);
+        cudaHostGetDevicePointer((void**)&dflag, (void*)hflag, 0);
+    }
+
+    // for worker
+    void wait_event_done(){
+      if (th_.joinable()) {
+        th_.join();  
+      }
+    }
+
+    // for worker
+    void stream_wait_event(int handler) {
+      auto stream = at::cuda::getCurrentCUDAStream();
+      cuStreamWaitValue32((CUstream)stream, dflag, notify_cnt, CU_STREAM_WAIT_VALUE_EQ);
+      th_ = std::thread([handler, this]{
+         fworker_->Wait(handler);
+         *(this->hflag) = this->notify_cnt;
+         ++(this->notify_cnt);      
+      });
+    }
+
+    void block_now_stream() {
+      auto stream = at::cuda::getCurrentCUDAStream();
+      cuStreamWaitValue32((CUstream)stream, dflag, notify_cnt, CU_STREAM_WAIT_VALUE_EQ);
+    }
+
+    // for server
+    void block_now_stream_and_get_batch() {
+      auto stream = at::cuda::getCurrentCUDAStream();
+      cuStreamWaitValue32((CUstream)stream, dflag, notify_cnt, CU_STREAM_WAIT_VALUE_EQ);
+      fut = std::async(std::launch::async, [this]{
+           auto ret = get_batch();
+           *(this->hflag) = this->notify_cnt;
+           ++(this->notify_cnt);
+           return ret;
+        });
+    }
+
+    // for server
+    std::vector<ServerDataBatch> get_future_batch_data(){
+      return fut.get();
+    }
+};
+
+void pybind_private(py::module &m){
+  py::class_<SimpleNotify>(m, "SimpleNotify")
+      .def(py::init<>())
+      .def("init", &SimpleNotify::init)
+      .def("block_now_stream_and_get_batch", &SimpleNotify::block_now_stream_and_get_batch)
+      .def("get_future_batch_data", &SimpleNotify::get_future_batch_data)
+      .def("block_now_stream", &SimpleNotify::block_now_stream)
+      .def("wait_event_done", &SimpleNotify::wait_event_done)
+      .def("stream_wait_event", &SimpleNotify::stream_wait_event);
+}
 #else
 void pybind_private(py::module &m){}
 #endif //DMLC_USE_CUDA
 
-#endif //PRIVATE_OPS_
\ No newline at end of file
+#endif //PRIVATE_OPS_
diff --git a/fserver/csrc/public.hpp b/fserver/csrc/public.hpp
index 93a1f18..005ab61 100644
--- a/fserver/csrc/public.hpp
+++ b/fserver/csrc/public.hpp
@@ -38,9 +38,6 @@ int instance_id_ = 0;
 int num_worker_ = 1;
 uint64_t worker_mask_ = 0x1;
 
-typedef std::tuple<uint64_t, std::vector<torch::Tensor>, std::vector<uint64_t>>
-    ServerDataBatch;
-
 std::mutex mu_;
 uint64_t handler_counter_ = 0;
 std::unordered_map<uint64_t, AFTensorMeta> meta_map_;
diff --git a/fserver/csrc/util.h b/fserver/csrc/util.h
index 9085c7f..7176d2d 100644
--- a/fserver/csrc/util.h
+++ b/fserver/csrc/util.h
@@ -20,4 +20,6 @@
 
 #ifndef UTIL_H_
 #define  UTIL_H_
+typedef std::tuple<uint64_t, std::vector<torch::Tensor>, std::vector<uint64_t>>
+    ServerDataBatch;
 #endif  // UTIL_H_