Changed Ext2ImageFileTestCase to use preferred ext back-end log2timel…

…ine#464

dfvfs/resolver/cache.py

@@ -3,6 +3,9 @@
 
 from __future__ import unicode_literals
 
+import collections
+import itertools
+
 from dfvfs.lib import errors
 
 
@@ -62,7 +65,7 @@ def __init__(self, maximum_number_of_cached_values):
 
     super(ObjectsCache, self).__init__()
     self._maximum_number_of_cached_values = maximum_number_of_cached_values
-    self._values = {}
+    self._values = collections.OrderedDict()
 
   def CacheObject(self, identifier, vfs_object):
     """Caches a VFS object.
@@ -129,6 +132,22 @@ def GetCacheValueByObject(self, vfs_object):
 
     return None, None
 
+  def GetLastObject(self):
+    """Retrieves the last cached object.
+
+    This method ignores the cache value reference count.
+
+    Returns:
+      object: the last cached VFS object or None if the cache is empty.
+    """
+    if not self._values:
+      return None
+
+    # Get the last (or most recent added) cache value.
+    cache_value = next(itertools.islice(
+        self._values.values(), len(self._values) - 1, None))
+    return cache_value.vfs_object
+
   def GetObject(self, identifier):
     """Retrieves a cached object based on the identifier.
 

dfvfs/resolver/context.py

@@ -63,6 +63,11 @@ def CacheFileSystem(self, path_spec, file_system):
 
   def Empty(self):
     """Empties the caches."""
+    file_object = self._file_object_cache.GetLastObject()
+    while file_object:
+      file_object.close()
+      file_object = self._file_object_cache.GetLastObject()
+
     self._file_object_cache.Empty()
     self._file_system_cache.Empty()
 

tests/resolver/cache.py

@@ -110,6 +110,8 @@ def testEmpty(self):
     cache_object.Empty()
     self.assertEqual(len(cache_object._values), 0)
 
+  # TODO: add tests for the GetLastObject method
+
   def testGetObject(self):
     """Tests the GetObject method."""
     cache_object = cache.ObjectsCache(1)