Adjust the exception hierachy

Group the exceptions into the following groups
  * Storage
  * Jobs
  * Execution
  * Other (wrapped failure here)

This grouping makes it easier to understand where
one type of exception should be used vs using another
type of exception.

Backwards incompatible changes:
  * StorageError -> StorageFailure
  * AlreadyExists -> Duplicate
  * WrappedFailure now inherits from Exception
    and not directly from TaskFlowException since it
    wraps arbitrary other exceptions and is not
    specific to taskflow.

Cleanups:
  * JobNotFound -> NotFound
  * EmptyFlow -> Empty
  * JobAlreadyExists -> AlreadyExists
  * InvariantViolation (X)
  * ConnectionFailure (X)

Change-Id: I0e1e81b513fbbc7adb8bfaa1244993e345ab70d3

1 files changed, 9 insertions, 8 deletions

diff --git a/taskflow/persistence/backends/impl_sqlalchemy.py b/taskflow/persistence/backends/impl_sqlalchemy.py
index fd91fdd..c61c357 100644
--- a/taskflow/persistence/backends/impl_sqlalchemy.py
+++ b/taskflow/persistence/backends/impl_sqlalchemy.py
@@ -308,14 +308,14 @@ class Connection(base.Connection):
                 return functor(session, *args, **kwargs)
         except sa_exc.SQLAlchemyError as e:
             LOG.exception('Failed running database session')
-            raise exc.StorageError("Storage backend internal error", e)
+            raise exc.StorageFailure("Storage backend internal error", e)
 
     def _make_session(self):
         try:
             return self._session_maker()
         except sa_exc.SQLAlchemyError as e:
             LOG.exception('Failed creating database session')
-            raise exc.StorageError("Failed creating database session", e)
+            raise exc.StorageFailure("Failed creating database session", e)
 
     def upgrade(self):
         try:
@@ -332,7 +332,7 @@ class Connection(base.Connection):
                     migration.db_sync(conn)
         except sa_exc.SQLAlchemyError as e:
             LOG.exception('Failed upgrading database version')
-            raise exc.StorageError("Failed upgrading database version", e)
+            raise exc.StorageFailure("Failed upgrading database version", e)
 
     def _clear_all(self, session):
         # NOTE(harlowja): due to how we have our relationship setup and
@@ -342,7 +342,7 @@ class Connection(base.Connection):
             return session.query(models.LogBook).delete()
         except sa_exc.DBAPIError as e:
             LOG.exception('Failed clearing all entries')
-            raise exc.StorageError("Failed clearing all entries", e)
+            raise exc.StorageFailure("Failed clearing all entries", e)
 
     def clear_all(self):
         return self._run_in_session(self._clear_all)
@@ -377,7 +377,7 @@ class Connection(base.Connection):
             session.delete(lb)
         except sa_exc.DBAPIError as e:
             LOG.exception('Failed destroying logbook')
-            raise exc.StorageError("Failed destroying logbook %s" % lb_id, e)
+            raise exc.StorageFailure("Failed destroying logbook %s" % lb_id, e)
 
     def destroy_logbook(self, book_uuid):
         return self._run_in_session(self._destroy_logbook, lb_id=book_uuid)
@@ -398,7 +398,7 @@ class Connection(base.Connection):
             return _convert_lb_to_external(lb_m)
         except sa_exc.DBAPIError as e:
             LOG.exception('Failed saving logbook')
-            raise exc.StorageError("Failed saving logbook %s" % lb.uuid, e)
+            raise exc.StorageFailure("Failed saving logbook %s" % lb.uuid, e)
 
     def save_logbook(self, book):
         return self._run_in_session(self._save_logbook, lb=book)
@@ -410,7 +410,8 @@ class Connection(base.Connection):
             return _convert_lb_to_external(lb)
         except sa_exc.DBAPIError as e:
             LOG.exception('Failed getting logbook')
-            raise exc.StorageError("Failed getting logbook %s" % book_uuid, e)
+            raise exc.StorageFailure("Failed getting logbook %s" % book_uuid,
+                                     e)
 
     def get_logbooks(self):
         session = self._make_session()
@@ -419,7 +420,7 @@ class Connection(base.Connection):
             books = [_convert_lb_to_external(lb) for lb in raw_books]
         except sa_exc.DBAPIError as e:
             LOG.exception('Failed getting logbooks')
-            raise exc.StorageError("Failed getting logbooks", e)
+            raise exc.StorageFailure("Failed getting logbooks", e)
         for lb in books:
             yield lb