RefPort's sometimes handled a time step late

src/lava/magma/core/model/py/ports.py

@@ -516,6 +516,24 @@ def write(
         """
         pass
 
+    # TODO: (PP) This should be optimized by a proper CSPSendPort wait
+    def wait(self):
+        """Method which block execution until (all) previous write requests have
+         been placed at the receiver. Calling wait() ensures that the value
+         written by the RefPort can be received (and set) by the VarPort at the
+         same time step. If wait() is not called, it is possible that the value
+         is received only at the next time step (non-deterministic).
+
+         >>> port = PyRefPort()
+         >>> port.write(5)
+         >>> # potentially do other stuff
+         >>> port.wait()  # waits until (all) previous writes have finished
+
+         Preliminary implementation. Currently, a simple read() ensures the
+         writes have been acknowledged. This is inefficient and will be
+         optimized later at the CspChannel level"""
+        self.read()
+
     def _transform(self, recv_data: np.array) -> np.array:
         """Applies all transformation function pointers to the input data.
 

src/lava/proc/io/dataloader.py

@@ -122,6 +122,7 @@ def run_post_mgmt(self) -> None:
         self.sample_id += 1
         if self.sample_id == len(self.dataset):
             self.sample_id = 0
+        self.state.wait()  # ensures write() has finished before moving on
 
 
 @implements(proc=StateDataloader, protocol=LoihiProtocol)

src/lava/proc/io/reset.py

@@ -58,7 +58,9 @@ def post_guard(self) -> None:
         return self.time_step % self.interval == self.offset
 
     def run_post_mgmt(self) -> None:
-        self.state.write(0 * self.state.read() + self.reset_value)
+        self.state.write(np.zeros(self.state._shape,
+                                  self.state._d_type) + self.reset_value)
+        self.state.wait()  # ensures write() has finished before moving on
 
 
 @implements(proc=Reset, protocol=LoihiProtocol)