Implement 2 new Id generators. Both are conflict-less.

generateNewLongId generates human-unfriendly ids based on zope transaction Ids.
generateNewLengthId generates human-friendly always increasing ids, with potential gaps between ids.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@9415 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Tool/IdTool.py

@@ -38,6 +38,7 @@ from Products.ERP5 import _dtmldir
 import threading
 
 from zLOG import LOG
+from BTrees.Length import Length
 
 class IdTool(UniqueObject, Folder):
   """
@@ -140,4 +141,61 @@ class IdTool(UniqueObject, Folder):
 
     return new_id
 
+  security.declareProtected(Permissions.AccessContentsInformation,
+                            'generateNewLongId')
+  def generateNewLongId(self, **kw):
+    """
+      Returns the ZODB transation id to be used as an identifier.
+      It's a 64bits number, so it can look ugly and/or huge to users.
+    """
+    tid = get_transaction()._id;
+    return (tid < 0) and (2**63 - tid) or tid; # It's a 64 bits number, but sometimes it returns as a negative int... so make it positive again and add 2**63.
+
+  security.declareProtected(Permissions.AccessContentsInformation,
+                            'copyDictLengthIds')
+  def getDictLengthIdsItems(self):
+    """
+      Return a copy of dict_length_ids.
+      This is a workaround to access the persistent mapping content from ZSQL
+      method to be able to insert initial tuples in the database at creation.
+    """
+    if getattr(self, 'dict_length_ids', None) is None:
+      self.dict_length_ids = PersistentMapping()
+    return self.dict_length_ids.items()
+
+  security.declareProtected(Permissions.AccessContentsInformation,
+                            'generateNewLengthId')
+  def generateNewLengthId(self, id_group=None, default=None):
+    """
+      Generates an Id.
+      The id is generated by mysql and then stored in a Length object in a
+      persistant mapping to be persistent.
+      We use MySQL to generate an ID, because it is atomic and we don't want
+      to generate any conflict at zope level. The possible downfall is that
+      some IDs might be skipped because of failed transactions (MySQL is not
+      and must not be rolled back).
+      2 ZSQL methods are required for this method to work :
+       - 
+      "Length" because the id is stored in a BTrees.Length. It doesn't have
+      to be a length.
+    """
+    if getattr(self, 'dict_length_ids', None) is None:
+      self.dict_length_ids = PersistentMapping()
+
+    new_id = None
+    if id_group not in (None, 'None'):
+      if not isinstance(id_group, str):
+        id_group = repr(id_group)
+      default = isinstance(default, int) and default or 1
+      query = getattr(self, 'Base_zGenerateId')
+      commit = getattr(self, 'Base_zCommit')
+      if None not in (query, commit):
+        result = query(id_group=id_group, default=default)
+        commit()
+        new_id = result[0]['LAST_INSERT_ID()']
+      if self.dict_length_ids.get(id_group) is None:
+        self.dict_length_ids[id_group]=Length(new_id)
+      self.dict_length_ids[id_group].set(new_id)
+    return new_id
+
 InitializeClass(IdTool)