[ZODB3] Allow serial to be returned as late as tpc_finish

----

kirr: This is likely to be ZODB3-backport of https://github.com/zopefoundation/ZODB/pull/69
Taken from https://lab.nexedi.com/nexedi/neoppod/blob/v1.12-52-gfb746e6b/ZODB3.patch

src/ZODB/interfaces.py

@@ -776,6 +776,10 @@ class IStorage(Interface):
         called while the storage transaction lock is held.  It takes
         the new transaction id generated by the transaction.
 
+        The return value can be either None or a serial giving new
+        serial for objects whose ids were passed to previous store calls
+        in the same transaction, and for which no serial was returned
+        from either store or tpc_vote for objects passed to store.
         """
 
     def tpc_vote(transaction):
@@ -794,8 +798,6 @@ class IStorage(Interface):
         The return value can be either None or a sequence of object-id
         and serial pairs giving new serials for objects who's ids were
         passed to previous store calls in the same transaction.
-        After the tpc_vote call, new serials must have been returned,
-        either from tpc_vote or store for objects passed to store.
 
         A serial returned in a sequence of oid/serial pairs, may be
         the special value ZODB.ConflictResolution.ResolvedSerial to

src/ZODB/tests/BasicStorage.py

@@ -72,8 +72,10 @@ class BasicStorage:
         r1 = self._storage.store(oid, None, zodb_pickle(MinPO(11)),
                                        '', txn)
         r2 = self._storage.tpc_vote(txn)
-        self._storage.tpc_finish(txn)
+        serial = self._storage.tpc_finish(txn)
         newrevid = handle_serials(oid, r1, r2)
+        if newrevid is None and serial is not None:
+            newrevid = serial
         data, revid = self._storage.load(oid, '')
         value = zodb_unpickle(data)
         eq(value, MinPO(11))

src/ZODB/tests/MTStorage.py

@@ -155,10 +155,12 @@ class StorageClientThread(TestThread):
         r2 = self.storage.tpc_vote(t)
         self.pause()
 
-        self.storage.tpc_finish(t)
+        serial = self.storage.tpc_finish(t)
         self.pause()
 
         revid = handle_serials(oid, r1, r2)
+        if serial is not None and revid is None:
+            revid = serial
         self.oids[oid] = revid
 
 class ExtStorageClientThread(StorageClientThread):

src/ZODB/tests/RevisionStorage.py

@@ -150,10 +150,12 @@ class RevisionStorage:
                 # Finish the transaction
                 r2 = self._storage.tpc_vote(t)
                 newrevid = handle_serials(oid, r1, r2)
-                self._storage.tpc_finish(t)
+                serial = self._storage.tpc_finish(t)
             except:
                 self._storage.tpc_abort(t)
                 raise
+            if serial is not None and newrevid is None:
+                newrevid = serial
             return newrevid
         revid1 = helper(1, None, 1)
         revid2 = helper(2, revid1, 2)

src/ZODB/tests/StorageTestBase.py

@@ -134,7 +134,7 @@ def handle_serials(oid, *args):
 
     A helper for function _handle_all_serials().
     """
-    return handle_all_serials(oid, *args)[oid]
+    return handle_all_serials(oid, *args).get(oid)
 
 def import_helper(name):
     __import__(name)
@@ -191,7 +191,9 @@ class StorageTestBase(ZODB.tests.util.TestCase):
             # Finish the transaction
             r2 = self._storage.tpc_vote(t)
             revid = handle_serials(oid, r1, r2)
-            self._storage.tpc_finish(t)
+            serial = self._storage.tpc_finish(t)
+            if serial is not None and revid is None:
+                revid = serial
         except:
             self._storage.tpc_abort(t)
             raise
@@ -211,8 +213,8 @@ class StorageTestBase(ZODB.tests.util.TestCase):
         self._storage.tpc_begin(t)
         undo_result = self._storage.undo(tid, t)
         vote_result = self._storage.tpc_vote(t)
-        self._storage.tpc_finish(t)
-        if expected_oids is not None:
+        serial = self._storage.tpc_finish(t)
+        if expected_oids is not None and serial is None:
             oids = undo_result and undo_result[1] or []
             oids.extend(oid for (oid, _) in vote_result or ())
             self.assertEqual(len(oids), len(expected_oids), repr(oids))

src/ZODB/tests/TransactionalUndoStorage.py

@@ -76,6 +76,12 @@ class TransactionalUndoStorage:
     def _transaction_newserial(self, oid):
         return self.__serials[oid]
 
+    def _transaction_finish(self, t, oid_list):
+        tid = self._storage.tpc_finish(t)
+        if tid is not None:
+            for oid in oid_list:
+                self.__serials[oid] = tid
+
     def _multi_obj_transaction(self, objs):
         newrevs = {}
         t = Transaction()
@@ -85,7 +91,7 @@ class TransactionalUndoStorage:
             self._transaction_store(oid, rev, data, '', t)
             newrevs[oid] = None
         self._transaction_vote(t)
-        self._storage.tpc_finish(t)
+        self._transaction_finish(t, [x[0] for x in objs])
         for oid in newrevs.keys():
             newrevs[oid] = self._transaction_newserial(oid)
         return newrevs
@@ -218,9 +224,9 @@ class TransactionalUndoStorage:
         self._transaction_store(oid2, revid2, p51, '', t)
         # Finish the transaction
         self._transaction_vote(t)
+        self._transaction_finish(t, [oid1, oid2])
         revid1 = self._transaction_newserial(oid1)
         revid2 = self._transaction_newserial(oid2)
-        self._storage.tpc_finish(t)
         eq(revid1, revid2)
         # Update those same two objects
         t = Transaction()
@@ -230,9 +236,9 @@ class TransactionalUndoStorage:
         self._transaction_store(oid2, revid2, p52, '', t)
         # Finish the transaction
         self._transaction_vote(t)
+        self._transaction_finish(t, [oid1, oid2])
         revid1 = self._transaction_newserial(oid1)
         revid2 = self._transaction_newserial(oid2)
-        self._storage.tpc_finish(t)
         eq(revid1, revid2)
         # Make sure the objects have the current value
         data, revid1 = self._storage.load(oid1, '')
@@ -288,8 +294,9 @@ class TransactionalUndoStorage:
         tid1 = info[1]['id']
         t = Transaction()
         oids = self._begin_undos_vote(t, tid, tid1)
-        self._storage.tpc_finish(t)
+        serial = self._storage.tpc_finish(t)
         # We get the finalization stuff called an extra time:
+        if serial is None:
             eq(len(oids), 4)
             unless(oid1 in oids)
             unless(oid2 in oids)
@@ -326,7 +333,7 @@ class TransactionalUndoStorage:
         self._transaction_store(oid2, revid2, p52, '', t)
         # Finish the transaction
         self._transaction_vote(t)
-        self._storage.tpc_finish(t)
+        self._transaction_finish(t, [oid1, oid2])
         revid1 = self._transaction_newserial(oid1)
         revid2 = self._transaction_newserial(oid2)
         eq(revid1, revid2)
@@ -346,7 +353,7 @@ class TransactionalUndoStorage:
         self._transaction_store(oid2, revid2, p53, '', t)
         # Finish the transaction
         self._transaction_vote(t)
-        self._storage.tpc_finish(t)
+        self._transaction_finish(t, [oid1, oid2])
         revid1 = self._transaction_newserial(oid1)
         revid2 = self._transaction_newserial(oid2)
         eq(revid1, revid2)
@@ -358,7 +365,8 @@ class TransactionalUndoStorage:
         tid = info[1]['id']
         t = Transaction()
         oids = self._begin_undos_vote(t, tid)
-        self._storage.tpc_finish(t)
+        serial = self._storage.tpc_finish(t)
+        if serial is None:
             eq(len(oids), 1)
             self.failUnless(oid1 in oids)
             self.failUnless(not oid2 in oids)
@@ -397,7 +405,7 @@ class TransactionalUndoStorage:
         self._transaction_store(oid1, revid1, p81, '', t)
         self._transaction_store(oid2, revid2, p91, '', t)
         self._transaction_vote(t)
-        self._storage.tpc_finish(t)
+        self._transaction_finish(t, [oid1, oid2])
         revid1 = self._transaction_newserial(oid1)
         revid2 = self._transaction_newserial(oid2)
         eq(revid1, revid2)
@@ -683,9 +691,9 @@ class TransactionalUndoStorage:
             tid = p64(i + 1)
             eq(txn.tid, tid)
 
-            L1 = [(rec.oid, rec.tid, rec.data_txn) for rec in txn]
-            L2 = [(oid, revid, None) for _tid, oid, revid in orig
-                  if _tid == tid]
+            L1 = {(rec.oid, rec.tid, rec.data_txn) for rec in txn}
+            L2 = {(oid, revid, None) for _tid, oid, revid in orig
+                  if _tid == tid}
 
             eq(L1, L2)