[Zope3-checkins] SVN: Zope3/trunk/src/zope/app/uniqueid/ A better 'random' unique id generation. Now we try to allocate ids

[Albertas Agejevas]

Log message for revision 25347:
A better 'random' unique id generation.  Now we try to allocate ids
sequentially, so they fall into the same BTree bucket.



-=-
Modified: Zope3/trunk/src/zope/app/uniqueid/__init__.py
===================================================================
--- Zope3/trunk/src/zope/app/uniqueid/__init__.py	2004-06-11 11:17:39 UTC (rev 25346)
+++ Zope3/trunk/src/zope/app/uniqueid/__init__.py	2004-06-11 12:18:20 UTC (rev 25347)
@@ -41,6 +41,8 @@
     __parent__ = None
     __name__ = None
 
+    _v_nextid = None
+
     def __init__(self):
         self.ids = OIBTree.OIBTree()
         self.refs = IOBTree.IOBTree()
@@ -59,10 +61,20 @@
         return self.ids[ref]
 
     def _generateId(self):
+        """Generate an id which is not yet taken.
+
+        This tries to allocate sequential ids so they fall into the
+        same BTree bucket, and randomizes if it stumbles upon a
+        used one.
+        """
         while True:
-            uid = random.randint(0, 2**31)
+            if self._v_nextid is None:
+                self._v_nextid = random.randint(0, 2**31)
+            uid = self._v_nextid
+            self._v_nextid += 1
             if uid not in self.refs:
                 return uid
+            self._v_nextid = None
 
     def register(self, ob):
         ob = trustedRemoveSecurityProxy(ob)

Modified: Zope3/trunk/src/zope/app/uniqueid/tests.py
===================================================================
--- Zope3/trunk/src/zope/app/uniqueid/tests.py	2004-06-11 11:17:39 UTC (rev 25346)
+++ Zope3/trunk/src/zope/app/uniqueid/tests.py	2004-06-11 12:18:20 UTC (rev 25347)
@@ -104,13 +104,28 @@
         result.sort()
         expected.sort()
         self.assertEquals(result, expected)
-        
+
         u.unregister(obj)
         u.unregister(obj2)
         self.assertEquals(len(u), 0)
         self.assertEquals(u.items(), [])
 
+    def test_getenrateId(self):
+        from zope.app.uniqueid import UniqueIdUtility
 
+        u = UniqueIdUtility()
+        self.assertEquals(u._v_nextid, None)
+        id1 = u._generateId()
+        self.assert_(u._v_nextid is not None)
+        id2 = u._generateId()
+        self.assert_(id1 + 1, id2)
+        u.refs[id2 + 1] = "Taken"
+        id3 = u._generateId()
+        self.assertNotEqual(id3, id2 + 1)
+        self.assertNotEqual(id3, id2)
+        self.assertNotEqual(id3, id1)
+
+
 class TestReferenceToPersistent(ReferenceSetupMixin, unittest.TestCase):
 
     def test(self):