Make transport module Mypy Compliant [issue#1731] (#2433)

* latest

* Delete =3.0.0

Signed-off-by: Md. Muhaimin Rahman <sezan92@gmail.com>

* Update src/lerobot/transport/utils.py

Signed-off-by: Md. Muhaimin Rahman <sezan92@gmail.com>

---------

Signed-off-by: Md. Muhaimin Rahman <sezan92@gmail.com>
Co-authored-by: Steven Palma <imstevenpmwork@ieee.org>

src/lerobot/transport/utils.py

@@ -19,7 +19,7 @@ import io
 import json
 import logging
 import pickle  # nosec B403: Safe usage for internal serialization only
-from multiprocessing import Event
+from multiprocessing.synchronize import Event as MpEvent
 from queue import Queue
 from typing import Any
 
@@ -28,6 +28,9 @@ import torch
 from lerobot.transport import services_pb2
 from lerobot.utils.transition import Transition
 
+# FIX for protobuf: Assign the enum to a variable and ignore the type error once
+TransferState = services_pb2.TransferState  # type: ignore[attr-defined]
+
 CHUNK_SIZE = 2 * 1024 * 1024  # 2 MB
 MAX_MESSAGE_SIZE = 4 * 1024 * 1024  # 4 MB
 
@@ -40,8 +43,8 @@ def bytes_buffer_size(buffer: io.BytesIO) -> int:
 
 
 def send_bytes_in_chunks(buffer: bytes, message_class: Any, log_prefix: str = "", silent: bool = True):
-    buffer = io.BytesIO(buffer)
-    size_in_bytes = bytes_buffer_size(buffer)
+    bytes_buffer: io.BytesIO = io.BytesIO(buffer)
+    size_in_bytes = bytes_buffer_size(bytes_buffer)
 
     sent_bytes = 0
 
@@ -50,15 +53,15 @@ def send_bytes_in_chunks(buffer: bytes, message_class: Any, log_prefix: str = ""
     logging_method(f"{log_prefix} Buffer size {size_in_bytes / 1024 / 1024} MB with")
 
     while sent_bytes < size_in_bytes:
-        transfer_state = services_pb2.TransferState.TRANSFER_MIDDLE
+        transfer_state = TransferState.TRANSFER_MIDDLE
 
         if sent_bytes + CHUNK_SIZE >= size_in_bytes:
-            transfer_state = services_pb2.TransferState.TRANSFER_END
+            transfer_state = TransferState.TRANSFER_END
         elif sent_bytes == 0:
-            transfer_state = services_pb2.TransferState.TRANSFER_BEGIN
+            transfer_state = TransferState.TRANSFER_BEGIN
 
         size_to_read = min(CHUNK_SIZE, size_in_bytes - sent_bytes)
-        chunk = buffer.read(size_to_read)
+        chunk = bytes_buffer.read(size_to_read)
 
         yield message_class(transfer_state=transfer_state, data=chunk)
         sent_bytes += size_to_read
@@ -67,7 +70,7 @@ def send_bytes_in_chunks(buffer: bytes, message_class: Any, log_prefix: str = ""
     logging_method(f"{log_prefix} Published {sent_bytes / 1024 / 1024} MB")
 
 
-def receive_bytes_in_chunks(iterator, queue: Queue | None, shutdown_event: Event, log_prefix: str = ""):
+def receive_bytes_in_chunks(iterator, queue: Queue | None, shutdown_event: MpEvent, log_prefix: str = ""):
     bytes_buffer = io.BytesIO()
     step = 0
 
@@ -78,17 +81,17 @@ def receive_bytes_in_chunks(iterator, queue: Queue | None, shutdown_event: Event
             logging.info(f"{log_prefix} Shutting down receiver")
             return
 
-        if item.transfer_state == services_pb2.TransferState.TRANSFER_BEGIN:
+        if item.transfer_state == TransferState.TRANSFER_BEGIN:
             bytes_buffer.seek(0)
             bytes_buffer.truncate(0)
             bytes_buffer.write(item.data)
             logging.debug(f"{log_prefix} Received data at step 0")
             step = 0
-        elif item.transfer_state == services_pb2.TransferState.TRANSFER_MIDDLE:
+        elif item.transfer_state == TransferState.TRANSFER_MIDDLE:
             bytes_buffer.write(item.data)
             step += 1
             logging.debug(f"{log_prefix} Received data at step {step}")
-        elif item.transfer_state == services_pb2.TransferState.TRANSFER_END:
+        elif item.transfer_state == TransferState.TRANSFER_END:
             bytes_buffer.write(item.data)
             logging.debug(f"{log_prefix} Received data at step end size {bytes_buffer_size(bytes_buffer)}")
 
@@ -109,17 +112,17 @@ def receive_bytes_in_chunks(iterator, queue: Queue | None, shutdown_event: Event
 
 def state_to_bytes(state_dict: dict[str, torch.Tensor]) -> bytes:
     """Convert model state dict to flat array for transmission"""
-    buffer = io.BytesIO()
+    bytes_buffer = io.BytesIO()
 
-    torch.save(state_dict, buffer)
+    torch.save(state_dict, bytes_buffer)
 
-    return buffer.getvalue()
+    return bytes_buffer.getvalue()
 
 
 def bytes_to_state_dict(buffer: bytes) -> dict[str, torch.Tensor]:
-    buffer = io.BytesIO(buffer)
-    buffer.seek(0)
-    return torch.load(buffer, weights_only=True)
+    bytes_buffer = io.BytesIO(buffer)
+    bytes_buffer.seek(0)
+    return torch.load(bytes_buffer, weights_only=True)
 
 
 def python_object_to_bytes(python_object: Any) -> bytes:
@@ -127,24 +130,24 @@ def python_object_to_bytes(python_object: Any) -> bytes:
 
 
 def bytes_to_python_object(buffer: bytes) -> Any:
-    buffer = io.BytesIO(buffer)
-    buffer.seek(0)
-    obj = pickle.load(buffer)  # nosec B301: Safe usage of pickle.load
+    bytes_buffer = io.BytesIO(buffer)
+    bytes_buffer.seek(0)
+    obj = pickle.load(bytes_buffer)  # nosec B301: Safe usage of pickle.load
     # Add validation checks here
     return obj
 
 
 def bytes_to_transitions(buffer: bytes) -> list[Transition]:
-    buffer = io.BytesIO(buffer)
-    buffer.seek(0)
-    transitions = torch.load(buffer, weights_only=True)
+    bytes_buffer = io.BytesIO(buffer)
+    bytes_buffer.seek(0)
+    transitions = torch.load(bytes_buffer, weights_only=True)
     return transitions
 
 
 def transitions_to_bytes(transitions: list[Transition]) -> bytes:
-    buffer = io.BytesIO()
-    torch.save(transitions, buffer)
-    return buffer.getvalue()
+    bytes_buffer = io.BytesIO()
+    torch.save(transitions, bytes_buffer)
+    return bytes_buffer.getvalue()
 
 
 def grpc_channel_options(