Use mutex to ensure only one thread has access at one time. (To be improved upon in the future)

Author: flyte

Diff for: xbee_helper/device.py

@@ -8,6 +8,7 @@
 from datetime import datetime
 from time import sleep
 from sys import version_info
+from multiprocessing import Lock
 
 from xbee import ZigBee as ZigBeeDevice
 
@@ -88,6 +89,7 @@ class ZigBee(object):
     """
     _rx_frames = {}
     _frame_id = 1
+    _lock = Lock()
 
     def __init__(self, ser):
         self._ser = ser
@@ -140,16 +142,17 @@ def _send_and_wait(self, **kwargs):
         """
         frame_id = self.next_frame_id
         kwargs.update(dict(frame_id=frame_id))
-        self._send(**kwargs)
-        timeout = datetime.now() + const.RX_TIMEOUT
-        while datetime.now() < timeout:
-            try:
-                frame = self._rx_frames.pop(frame_id)
-                raise_if_error(frame)
-                return frame
-            except KeyError:
-                sleep(0.1)
-                continue
+        with self._lock:
+            self._send(**kwargs)
+            timeout = datetime.now() + const.RX_TIMEOUT
+            while datetime.now() < timeout:
+                try:
+                    frame = self._rx_frames.pop(frame_id)
+                    raise_if_error(frame)
+                    return frame
+                except KeyError:
+                    sleep(0.1)
+                    continue
         _LOGGER.exception(
             "Did not receive response within configured timeout period.")
         raise exceptions.ZigBeeResponseTimeout()