Use inter-process mutex to prevent concurrent neoVI device open

When neoVI server is enabled, there is an issue with concurrent device open.

Author: Pierre-Luc Tessier Gagné

can/interfaces/ics_neovi/neovi_bus.py

@@ -11,9 +11,12 @@
 """
 
 import logging
+import os
+import tempfile
 from collections import deque
 
 from can import Message, CanError, BusABC
+from filelock import FileLock
 
 logger = logging.getLogger(__name__)
 
@@ -122,7 +125,14 @@ def __init__(self, channel, can_filters=None, **kwargs):
         type_filter = kwargs.get("type_filter")
         serial = kwargs.get("serial")
         self.dev = self._find_device(type_filter, serial)
-        ics.open_device(self.dev)
+
+        # Use inter-process mutex to prevent concurrent device open.
+        # When neoVI server is enabled, there is an issue with concurrent
+        # device open.
+        open_lock = FileLock(
+            os.path.join(tempfile.gettempdir(), 'neovi.lock'))
+        with open_lock:
+            ics.open_device(self.dev)
 
         if "bitrate" in kwargs:
             for channel in self.channels:

setup.py

@@ -90,6 +90,7 @@
         "wrapt~=1.10",
         "aenum",
         'windows-curses;platform_system=="Windows"',
+        'filelock'
     ],
     setup_requires=["pytest-runner"],
     extras_require=extras_require,