storage: fix crash when a client loses connection to the master just before voting

This is similar to commit 7aecdada
and for completeness, we also protect unlock the same way.

neo/client/app.py

@@ -647,6 +647,10 @@ class Application(ThreadedApplication):
             txn_context['voted'] = None
             # We must not go further if connection to master was lost since
             # tpc_begin, to lower the probability of failing during tpc_finish.
+            # IDEA: We can improve in 2 opposite directions:
+            #       - In the case of big transactions, it would be useful to
+            #         also detect failures earlier.
+            #       - If possible, recover from master failure.
             if 'error' in txn_context:
                 raise NEOStorageError(txn_context['error'])
             return result

neo/storage/transactions.py

@@ -162,7 +162,10 @@ class TransactionManager(object):
             Store transaction information received from client node
         """
         logging.debug('Vote TXN %s', dump(ttid))
-        transaction = self._transaction_dict[ttid]
+        try:
+            transaction = self._transaction_dict[ttid]
+        except KeyError:
+            raise ProtocolError("unknown ttid %s" % dump(ttid))
         object_list = transaction.getObjectList()
         if txn_info:
             user, desc, ext, oid_list = txn_info
@@ -195,7 +198,10 @@ class TransactionManager(object):
         """
             Unlock transaction
         """
-        tid = self._transaction_dict[ttid].getTID()
+        try:
+            tid = self._transaction_dict[ttid].getTID()
+        except KeyError:
+            raise ProtocolError("unknown ttid %s" % dump(ttid))
         logging.debug('Unlock TXN %s (ttid=%s)', dump(tid), dump(ttid))
         dm = self._app.dm
         dm.unlockTransaction(tid, ttid)

neo/tests/threaded/test.py

@@ -1135,6 +1135,25 @@ class Test(NEOThreadedTest):
         finally:
             cluster.stop()
 
+    def testMasterFailureBeforeVote(self):
+        def waitStoreResponses(orig, *args):
+            result = orig(*args)
+            m2c, = cluster.master.getConnectionList(orig.__self__)
+            m2c.close()
+            self.tic()
+            return result
+        cluster = NEOCluster(storage_count=2, partitions=2)
+        try:
+            cluster.start()
+            t, c = cluster.getTransaction()
+            c.root()['x'] = PCounter() # 1 store() to each storage
+            with Patch(cluster.client, waitStoreResponses=waitStoreResponses):
+                self.assertRaises(POSException.StorageError, t.commit)
+            self.assertEqual(cluster.neoctl.getClusterState(),
+                             ClusterStates.RUNNING)
+        finally:
+            cluster.stop()
+
     def testEmptyTransaction(self):
         cluster = NEOCluster()
         try: