Let make_db_file_path accept epoch=None

...in which case it should strip the epoch if the original path had one.

Change-Id: I8739a474c56c0f2376a276d2691c84448cb9c647

swift/common/utils.py

@@ -5370,22 +5370,24 @@ def make_db_file_path(db_path, epoch):
     Given a path to a db file, return a modified path whose filename part has
     the given epoch.
 
-    A db filename takes the form <hash>[_<epoch>].db; this method replaces the
+    A db filename takes the form ``<hash>[_<epoch>].db``; this method replaces
-    <epoch> part of the given ``db_path`` with the given ``epoch`` value.
+    the ``<epoch>`` part of the given ``db_path`` with the given ``epoch``
+    value, or drops the epoch part if the given ``epoch`` is ``None``.
 
     :param db_path: Path to a db file that does not necessarily exist.
-    :param epoch: A string that will be used as the epoch in the new path's
+    :param epoch: A string (or ``None``) that will be used as the epoch
-        filename; the value will be normalized to the normal string
+        in the new path's filename; non-``None`` values will be
-        representation of a :class:`~swift.common.utils.Timestamp`.
+        normalized to the normal string representation of a
+        :class:`~swift.common.utils.Timestamp`.
     :return: A modified path to a db file.
     :raises ValueError: if the ``epoch`` is not valid for constructing a
         :class:`~swift.common.utils.Timestamp`.
     """
-    if epoch is None:
-        raise ValueError('epoch must not be None')
-    epoch = Timestamp(epoch).normal
     hash_, _, ext = parse_db_filename(db_path)
     db_dir = os.path.dirname(db_path)
+    if epoch is None:
+        return os.path.join(db_dir, hash_ + ext)
+    epoch = Timestamp(epoch).normal
     return os.path.join(db_dir, '%s_%s%s' % (hash_, epoch, ext))
 
 

swift/container/backend.py

@@ -329,9 +329,7 @@ class ContainerBroker(DatabaseBroker):
         if db_file == ':memory:':
             base_db_file = db_file
         else:
-            db_dir = os.path.dirname(db_file)
+            base_db_file = make_db_file_path(db_file, None)
-            hash_, other, ext = parse_db_filename(db_file)
-            base_db_file = os.path.join(db_dir, hash_ + ext)
         super(ContainerBroker, self).__init__(
             base_db_file, timeout, logger, account, container, pending_timeout,
             stale_reads_ok, skip_commits=skip_commits)
@@ -361,9 +359,8 @@ class ContainerBroker(DatabaseBroker):
         """
         hsh = hash_path(account, container)
         db_dir = storage_directory(DATADIR, part, hsh)
-        db_path = os.path.join(device_path, db_dir, hsh + '.db')
+        db_path = make_db_file_path(
-        if epoch:
+            os.path.join(device_path, db_dir, hsh + '.db'), epoch)
-            db_path = make_db_file_path(db_path, epoch)
         broker = ContainerBroker(db_path, account=account, container=container,
                                  logger=logger)
         if not os.path.exists(broker.db_file):

test/unit/common/test_utils.py

@@ -3955,6 +3955,11 @@ cluster_dfw1 = http://dfw1.host/v1/
         actual = utils.make_db_file_path(actual, epoch)
         self.assertEqual('/path/to/hash_%s.db' % epoch.internal, actual)
 
+        # None strips epoch
+        self.assertEqual('hash.db', utils.make_db_file_path('hash.db', None))
+        self.assertEqual('/path/to/hash.db', utils.make_db_file_path(
+            '/path/to/hash_withepoch.db', None))
+
         # epochs shouldn't have offsets
         epoch = utils.Timestamp.now(offset=10)
         actual = utils.make_db_file_path(actual, epoch)
@@ -3963,9 +3968,6 @@ cluster_dfw1 = http://dfw1.host/v1/
         self.assertRaises(ValueError, utils.make_db_file_path,
                           '/path/to/hash.db', 'bad epoch')
 
-        self.assertRaises(ValueError, utils.make_db_file_path,
-                          '/path/to/hash.db', None)
-
     def test_modify_priority(self):
         pid = os.getpid()
         logger = debug_logger()