exception decorator and mail send for errors and changes to rec state checker

backend/tools/exception_decorator.py

@@ -0,0 +1,13 @@
+from backend import LrcException
+
+
+def exception_decorator(*exceptions):
+    def decorator(func):
+        def new_func(*args, **kwargs):
+            try:
+                ret = func(*args, **kwargs)
+                return ret
+            except exceptions as e:
+                raise LrcException(e)
+        return new_func
+    return decorator