ERP5Type/Base.py: Store a result of getCreationDate and returns it next time....

ERP5Type/Base.py: Store a result of getCreationDate and returns it next time. Otherwise if there is a very long history, getCreationDate becomes slow because of append-optimized data structure of WorkflowHistoryList.

product/ERP5Type/Base.py

@@ -3131,12 +3131,16 @@ class Base( CopyContainer,
     """
       Returns the creation date of the document based on workflow information
     """
+    if getattr(self, '_creation_date', None) is not None:
+      return DateTime(self._creation_date)
+
     # Check if edit_workflow defined
     portal_workflow = self.getPortalObject().portal_workflow
     wf = portal_workflow.getWorkflowById('edit_workflow')
     wf_list = portal_workflow.getWorkflowsFor(self)
     if wf is not None:
       wf_list = [wf] + wf_list
+    result = None
     for wf in wf_list:
       try:
         history = wf.getInfoFor(self, 'history', None)
@@ -3144,9 +3148,13 @@ class Base( CopyContainer,
         history = None
       if history is not None and len(history):
         # Then get the first line of edit_workflow
-        return history[0].get('time', None)
+        result = history[0].get('time', None)
+    if result is None:
       if getattr(aq_base(self), 'CreationDate', None) is not None:
-      return asDate(self.CreationDate())
+        result = asDate(self.CreationDate())
+    if result is not None:
+      self._creation_date = DateTime(result)
+      return result
     return None # JPS-XXX - try to find a way to return a creation date instead of None
 
   security.declareProtected(Permissions.AccessContentsInformation, 'getModificationDate')