Removed the feature to try to save the index periodically because:

1. The saving was performed in (tpc)_finish.  It is important that this
   method do as little as possible because it cannot fail!

2. The algorithm for deciding how often to save was broken. For large
   databases, for which saving periodically is desireable, the period
   was set so high that the index was effectively never saved.

It might be nice to save periodically, but doing so is tricky, since
we really don't want to do it during commit.  Until we figure out how
to do this right, it is better not to try.

In the mean time, we save on close and on pack, which is proably often
enough in most cases.

src/ZODB/FileStorage/FileStorage.py

@@ -92,8 +92,6 @@ class FileStorage(BaseStorage.BaseStorage,
     # Set True while a pack is in progress; undo is blocked for the duration.
     _pack_is_in_progress = False
 
-    _records_before_save = 10000
-
     def __init__(self, file_name, create=False, read_only=False, stop=None,
                  quota=None):
 
@@ -168,8 +166,6 @@ class FileStorage(BaseStorage.BaseStorage,
                 )
             self._save_index()
 
-        self._records_before_save = max(self._records_before_save,
-                                        len(self._index))
         self._ltid = tid
 
         # self._pos should always point just past the last
@@ -815,9 +811,6 @@ class FileStorage(BaseStorage.BaseStorage,
         finally:
             self._lock_release()
 
-    # Keep track of the number of records that we've written
-    _records_written = 0
-
     def _finish(self, tid, u, d, e):
         nextpos=self._nextpos
         if nextpos:
@@ -835,15 +828,6 @@ class FileStorage(BaseStorage.BaseStorage,
             self._index.update(self._tindex)
             self._vindex.update(self._tvindex)
 
-            # Update the number of records that we've written
-            # +1 for the transaction record
-            self._records_written += len(self._tindex) + 1
-            if self._records_written >= self._records_before_save:
-                self._save_index()
-                self._records_written = 0
-                self._records_before_save = max(self._records_before_save,
-                                                len(self._index))
-
         self._ltid = tid
 
     def _abort(self):

src/ZODB/tests/testFileStorage.py

@@ -221,26 +221,6 @@ class FileStorageTests(
         self.open()
         self.assertEqual(self._storage._oid, true_max_oid)
 
-    # This would make the unit tests too slow
-    # check_save_after_load_that_worked_hard(self)
-
-    def check_periodic_save_index(self):
-
-        # Check the basic algorithm
-        oldsaved = self._storage._saved
-        self._storage._records_before_save = 10
-        for i in range(4):
-            self._dostore()
-        self.assertEqual(self._storage._saved, oldsaved)
-        self._dostore()
-        self.assertEqual(self._storage._saved, oldsaved+1)
-
-        # Now make sure the parameter changes as we get bigger
-        for i in range(20):
-            self._dostore()
-
-        self.failUnless(self._storage._records_before_save > 20)
-
     def checkStoreBumpsOid(self):
         # If .store() is handed an oid bigger than the storage knows
         # about already, it's crucial that the storage bump its notion