- Fixed bug in unit of work whereby a joined-inheritance

  subclass could insert the row for the "sub" table
  before the parent table, if the two tables had no
  ForeignKey constraints set up between them.
  Also in 0.7.11. [ticket:2689]
- fix a glitch in the assertsql.CompiledSQL fixture regarding
when a multiparam compiledSQL is used within an AllOf
- add a new utility function randomize_unitofwork() which
does the function of --reversetop

2 files changed, 51 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 2d7f62153..d258a20b6 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -2002,10 +2002,20 @@ class Mapper(_InspectionAttr):
     @_memoized_configured_property
     def _sorted_tables(self):
         table_to_mapper = {}
+
         for mapper in self.base_mapper.self_and_descendants:
             for t in mapper.tables:
                 table_to_mapper.setdefault(t, mapper)
 
+        extra_dependencies = []
+        for table, mapper in table_to_mapper.items():
+            super_ = mapper.inherits
+            if super_:
+                extra_dependencies.extend([
+                    (super_table, table)
+                    for super_table in super_.tables
+                    ])
+
         def skip(fk):
             # attempt to skip dependencies that are not
             # significant to the inheritance chain
@@ -2017,7 +2027,7 @@ class Mapper(_InspectionAttr):
             if parent is not None and \
                 dep is not None and \
                 dep is not parent and \
-                dep.inherit_condition is not None:
+                    dep.inherit_condition is not None:
                 cols = set(sql_util.find_columns(dep.inherit_condition))
                 if parent.inherit_condition is not None:
                     cols = cols.union(sql_util.find_columns(
@@ -2028,7 +2038,9 @@ class Mapper(_InspectionAttr):
             return False
 
         sorted_ = sql_util.sort_tables(table_to_mapper.iterkeys(),
-                                    skip_fn=skip)
+                                    skip_fn=skip,
+                                    extra_dependencies=extra_dependencies)
+
         ret = util.OrderedDict()
         for t in sorted_:
             ret[t] = table_to_mapper[t]
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index cc9dd6ba5..f3b8e271d 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -1265,3 +1265,40 @@ def attribute_str(instance, attribute):
 
 def state_attribute_str(state, attribute):
     return state_str(state) + "." + attribute
+
+
+def randomize_unitofwork():
+    """Use random-ordering sets within the unit of work in order
+    to detect unit of work sorting issues.
+
+    This is a utility function that can be used to help reproduce
+    inconsistent unit of work sorting issues.   For example,
+    if two kinds of objects A and B are being inserted, and
+    B has a foreign key reference to A - the A must be inserted first.
+    However, if there is no relationship between A and B, the unit of work
+    won't know to perform this sorting, and an operation may or may not
+    fail, depending on how the ordering works out.   Since Python sets
+    and dictionaries have non-deterministic ordering, such an issue may
+    occur on some runs and not on others, and in practice it tends to
+    have a great dependence on the state of the interpreter.  This leads
+    to so-called "heisenbugs" where changing entirely irrelevant aspects
+    of the test program still cause the failure behavior to change.
+
+    By calling ``randomize_unitofwork()`` when a script first runs, the
+    ordering of a key series of sets within the unit of work implementation
+    are randomized, so that the script can be minimized down to the fundamental
+    mapping and operation that's failing, while still reproducing the issue
+    on at least some runs.
+
+    This utility is also available when running the test suite via the
+    ``--reversetop`` flag.
+
+    .. versionadded:: 0.8.1 created a standalone version of the
+       ``--reversetop`` feature.
+
+    """
+    from sqlalchemy.orm import unitofwork, session, mapper, dependency
+    from sqlalchemy.util import topological
+    from sqlalchemy.testing.util import RandomSet
+    topological.set = unitofwork.set = session.set = mapper.set = \
+            dependency.set = RandomSet