MemcachedTool: revert "Simplify code."

This reverts commit 8e0674d8.

This fixes a regression in test_Member_download_pdf_format (testDmsWithFlare).

product/ERP5Type/Tool/MemcachedTool.py

@@ -26,6 +26,7 @@
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #
 ##############################################################################
+import time
 from Products.ERP5Type.Tool.BaseTool import BaseTool
 from Products.ERP5Type import Permissions, _dtmldir
 from AccessControl import ClassSecurityInfo
@@ -101,6 +102,9 @@ if memcache is not None:
       # DELETE_ACTION: delete on server
       self.scheduled_action_dict = {}
       self.server_list = server_list
+      # see "Expiration times" from memcached protocol docs
+      # (this simulates relative expiration time greater than 30 days)
+      self.expiration_time_since_epoch = expiration_time >= 2592000
       self.expiration_time = expiration_time
       self.server_max_key_length = server_max_key_length
       self.server_max_value_length = server_max_value_length
@@ -122,6 +126,8 @@ if memcache is not None:
       """
       try:
         expiration_time = self.expiration_time
+        if self.expiration_time_since_epoch:
+          expiration_time += time.time()
         for key, value in self.local_cache.iteritems():
           if getattr(value, MEMCACHED_TOOL_MODIFIED_FLAG_PROPERTY_ID, None):
             delattr(value, MEMCACHED_TOOL_MODIFIED_FLAG_PROPERTY_ID)