Add + use helper to raise + chain exceptions

Ensure that on python versions that can retain
the exceptions associated chain/causes that we make
an attempt to retain them, on versions of python
that do not have this at least attempt to retain the
chain (but we will not get the nice stack formatting
that comes along with that).

Change-Id: I7b46854c3969463009c39be28a3131d2d3179c82

1 files changed, 6 insertions, 2 deletions

diff --git a/tooz/drivers/pgsql.py b/tooz/drivers/pgsql.py
index 548a99d..b5abca5 100644
--- a/tooz/drivers/pgsql.py
+++ b/tooz/drivers/pgsql.py
@@ -83,7 +83,9 @@ def _translating_cursor(conn):
         with conn.cursor() as cur:
             yield cur
     except psycopg2.Error as e:
-        raise coordination.ToozError(_format_exception(e))
+        coordination.raise_with_cause(coordination.ToozError,
+                                      _format_exception(e),
+                                      cause=e)
 
 
 class PostgresLock(locking.Lock):
@@ -209,4 +211,6 @@ class PostgresDriver(coordination.CoordinationDriver):
                                     password=password,
                                     database=dbname)
         except psycopg2.Error as e:
-            raise coordination.ToozConnectionError(_format_exception(e))
+            coordination.raise_with_cause(coordination.ToozConnectionError,
+                                          _format_exception(e),
+                                          cause=e)