Handle old ghost items

axiom/item.py

@@ -761,7 +761,8 @@ def checkpoint(self):
                 # don't issue duplicate SQL and crap; we were created, then
                 # destroyed immediately.
                 return
-            self.store.executeSQL(self._baseDeleteSQL(self.store), [self.storeID])
+            self.store.executeSQL(self._baseDeleteSQL(self.store),
+                                  [self.storeID])
             # re-using OIDs plays havoc with the cache, and with other things
             # as well.  We need to make sure that we leave a placeholder row at
             # the end of the table.
@@ -770,16 +771,17 @@ def checkpoint(self):
                 self.store.executeSchemaSQL(_schema.CHANGE_TYPE,
                                             [-1, self.storeID])
 
-                # Can't do this any more:
-                # self.store.executeSchemaSQL(_schema.DELETE_OBJECT, [self.storeID])
+                # I want to do this to reclaim the space, but I can't because
+                # the ID allocation algorithm depends on the fact that old
+                # objects aren't recycled:
+
+                # self.store.executeSchemaSQL(_schema.DELETE_OBJECT,
+                #                             [self.storeID])
 
                 # TODO: need to measure the performance impact of this, then do
                 # it to make sure things are in fact deleted:
                 # self.store.executeSchemaSQL(_schema.APP_VACUUM)
 
-            else:
-                assert self.__legacy__
-
             # we're done...
             if self.store.autocommit:
                 self.committed()

axiom/store.py

@@ -2302,6 +2302,17 @@ def getItemByID(self, storeID, default=_noItem, autoUpgrade=True):
             # for the moment we're going to assume no inheritance
             attrs = self.querySQL(T._baseSelectSQL(self), [storeID])
             if len(attrs) == 0:
+                # there was an oid allocation row with a type set to a valid
+                # type, but no accompanying data row.
+
+                # there are cases where items will be deleted but their oid
+                # allocation rows won't be.  normally this should set the type
+                # to -1 but upgraders or old bugs may have left the database
+                # in a state where it's still set.
+
+                # do cleanup if we're not in a read-only transaction (haha
+                # there is no such thing as a read-only transaction)
+                self.executeSchemaSQL(_schema.CHANGE_TYPE, [-1, storeID])
                 if default is _noItem:
                     raise errors.ItemNotFound(
                         'No results for known-to-be-good object')

axiom/test/test_item.py

@@ -656,3 +656,25 @@ class TI3(Item):
             [(TestInterface2, 20),
              (TestInterface, 0)])
         self.assertTrue(TestInterface.implementedBy(TI3))
+
+
+    def test_fixDangling(self):
+        st = store.Store()
+        i = itemtest.PlainItem(store=st)
+        oldStoreID = i.storeID
+        self.assertEquals(st.getItemByID(oldStoreID, default=1234),
+                          i)
+
+        # this magic keyword argument actually simulates an old bug, but rather
+        # than carry around a legacy database, we'll just call an internal API,
+        # because this is actually used by upgraders as well (e.g. a subtly
+        # buggy upgrader could leave the DB in the same state as this old bug)
+
+        i.deleteFromStore(deleteObject=False)
+
+        self.assertEquals(st.getItemByID(oldStoreID+100, default=1234),
+                          1234)
+
+        self.assertEquals(st.getItemByID(oldStoreID, default=1234),
+                          1234)
+