changes to make app.current_request thread safe when running chalice …

…locally

- fixes race conditions that can occur when chalice is being run locally
  and it handling multiple concurrent requests

chalice/local.py

@@ -47,7 +47,10 @@ def time(self):
 
 def create_local_server(app_obj, config, host, port):
     # type: (Chalice, Config, str, int) -> LocalDevServer
-    return LocalDevServer(app_obj, config, host, port)
+    local_app_opj = app_obj  # type: LocalChalice
+    local_app_opj.__class__ = LocalChalice
+    local_app_opj.initialize_current_request_lookup()
+    return LocalDevServer(local_app_opj, config, host, port)
 
 
 class LocalARNBuilder(object):
@@ -661,3 +664,28 @@ def shutdown(self):
         # type: () -> None
         if self._server is not None:
             self._server.shutdown()
+
+
+class LocalChalice(Chalice):
+    def __init__(self, *args, **kwargs):
+        # type: (Any, Any) -> None
+        self._current_request_lookup = {}  # type: Dict[int, dict]
+        super(LocalChalice, self).__init__(*args, **kwargs)
+
+    def initialize_current_request_lookup(self):
+        # type: () -> None
+        self._current_request_lookup = {}
+
+    @property
+    def current_request(self):  # noqa
+        # type: () -> Optional[Request]
+        thread_id = threading.current_thread().ident
+        assert thread_id is not None
+        return self._current_request_lookup.get(thread_id, None)
+
+    @current_request.setter
+    def current_request(self, value):  # noqa
+        # type: (Request) -> None
+        thread_id = threading.current_thread().ident
+        assert thread_id is not None
+        self._current_request_lookup[thread_id] = value