Added a client-storage check to make sure a client doesn't connect to

an out-of-date server.

src/ZEO/ClientStorage.py

@@ -1219,6 +1219,10 @@ class ClientStorage(object):
                 log2("No verification necessary (last_inval_tid up-to-date)")
                 self.finish_verification()
                 return "no verification"
+            elif ltid < last_inval_tid:
+                message = "Client has seen newer trasnactions than server!"
+                log2(message, level=logging.CRITICAL)
+                raise ClientStorageError(message)
 
             # log some hints about last transaction
             log2("last inval tid: %r %s\n"

src/ZEO/tests/ConnectionTests.py

@@ -198,11 +198,13 @@ class CommonSetupTearDown(StorageTestBase):
             zconf.transaction_timeout = self.timeout
         return zconf
 
-    def startServer(self, create=1, index=0, read_only=0, ro_svr=0, keep=None):
+    def startServer(self, create=1, index=0, read_only=0, ro_svr=0, keep=None,
+                    path=None):
         addr = self.addr[index]
         logging.info("startServer(create=%d, index=%d, read_only=%d) @ %s" %
                      (create, index, read_only, addr))
-        path = "%s.%d" % (self.file, index)
+        if path is None:
+            path = "%s.%d" % (self.file, index)
         sconf = self.getConfig(path, create, read_only)
         zconf = self.getServerConfig(addr, ro_svr)
         if keep is None:
@@ -268,30 +270,6 @@ class ConnectionTests(CommonSetupTearDown):
         self._dostore(oid, data=obj)
         self._storage.close()
 
-    def checkMultipleServers(self):
-        # Crude test-- just start two servers and do a commit at each one.
-
-        self._newAddr()
-        self._storage = self.openClientStorage('test', 100000)
-        self._dostore()
-
-        self.shutdownServer(index=0)
-        self.startServer(index=1)
-
-        # If we can still store after shutting down one of the
-        # servers, we must be reconnecting to the other server.
-
-        did_a_store = 0
-        for i in range(10):
-            try:
-                self._dostore()
-                did_a_store = 1
-                break
-            except ClientDisconnected:
-                time.sleep(0.5)
-        self.assert_(did_a_store)
-        self._storage.close()
-
     def checkReadOnlyClient(self):
         # Open a read-only client to a read-write server; stores fail
 
@@ -341,33 +319,6 @@ class ConnectionTests(CommonSetupTearDown):
         self.assertRaises(ReadOnlyError, self._dostore)
         self._storage.close()
 
-    # TODO:  Compare checkReconnectXXX() here to checkReconnection()
-    # further down.  Is the code here hopelessly naive, or is
-    # checkReconnection() overwrought?
-
-    def checkReconnectWritable(self):
-        # A read-write client reconnects to a read-write server
-
-        # Start a client
-        self._storage = self.openClientStorage()
-        # Stores should succeed here
-        self._dostore()
-
-        # Shut down the server
-        self.shutdownServer()
-        self._servers = []
-        # Poll until the client disconnects
-        self.pollDown()
-        # Stores should fail now
-        self.assertRaises(ClientDisconnected, self._dostore)
-
-        # Restart the server
-        self.startServer(create=0)
-        # Poll until the client connects
-        self.pollUp()
-        # Stores should succeed here
-        self._dostore()
-        self._storage.close()
 
     def checkDisconnectionError(self):
         # Make sure we get a ClientDisconnected when we try to read an
@@ -379,41 +330,6 @@ class ConnectionTests(CommonSetupTearDown):
                           self._storage.load, 'fredwash', '')
         self._storage.close()
 
-    def checkDisconnectedAbort(self):
-        self._storage = self.openClientStorage()
-        self._dostore()
-        oids = [self._storage.new_oid() for i in range(5)]
-        txn = Transaction()
-        self._storage.tpc_begin(txn)
-        for oid in oids:
-            data = zodb_pickle(MinPO(oid))
-            self._storage.store(oid, None, data, '', txn)
-        self.shutdownServer()
-        self.assertRaises(ClientDisconnected, self._storage.tpc_vote, txn)
-        self._storage.tpc_abort(txn)
-        self.startServer(create=0)
-        self._storage._wait()
-        self._dostore()
-
-        # This test is supposed to cover the following error, although
-        # I don't have much confidence that it does.  The likely
-        # explanation for the error is that the _tbuf contained
-        # objects that weren't in the _seriald, because the client was
-        # interrupted waiting for tpc_vote() to return.  When the next
-        # transaction committed, it tried to do something with the
-        # bogus _tbuf entries.  The explanation is wrong/incomplete,
-        # because tpc_begin() should clear the _tbuf.
-
-        # 2003-01-15T15:44:19 ERROR(200) ZODB A storage error occurred
-        # in the last phase of a two-phase commit.  This shouldn't happen.
-
-        # Traceback (innermost last):
-        # Module ZODB.Transaction, line 359, in _finish_one
-        # Module ZODB.Connection, line 691, in tpc_finish
-        # Module ZEO.ClientStorage, line 679, in tpc_finish
-        # Module ZEO.ClientStorage, line 709, in _update_cache
-        # KeyError: ...
-
     def checkBasicPersistence(self):
         # Verify cached data persists across client storage instances.
 
@@ -539,33 +455,6 @@ class ConnectionTests(CommonSetupTearDown):
         self.assertEqual(newobj_copy, newobj)
         self._storage.close()
 
-    def checkReconnection(self):
-        # Check that the client reconnects when a server restarts.
-
-        self._storage = self.openClientStorage()
-        oid = self._storage.new_oid()
-        obj = MinPO(12)
-        self._dostore(oid, data=obj)
-        logging.info("checkReconnection(): About to shutdown server")
-        self.shutdownServer()
-        logging.info("checkReconnection(): About to restart server")
-        self.startServer(create=0)
-        oid = self._storage.new_oid()
-        obj = MinPO(12)
-        while 1:
-            try:
-                self._dostore(oid, data=obj)
-                break
-            except ClientDisconnected:
-                # Maybe the exception mess is better now
-                logging.info("checkReconnection(): Error after"
-                             " server restart; retrying.", exc_info=True)
-                transaction.abort()
-            # Give the other thread a chance to run.
-            time.sleep(0.1)
-        logging.info("checkReconnection(): finished")
-        self._storage.close()
-
     def checkBadMessage1(self):
         # not even close to a real message
         self._bad_message("salty")
@@ -676,6 +565,20 @@ class ConnectionTests(CommonSetupTearDown):
         db2.close()
         db1.close()
 
+    def checkCheckForOutOfDateServer(self):
+        # We don't want to connect a client to a server if the client
+        # has seen newer transactions.
+        self._storage = self.openClientStorage()
+        self._dostore()
+        self.shutdownServer()
+        self.assertRaises(ClientDisconnected, self._storage.load, '\0'*8, '')
+
+        self.startServer()
+
+        # No matter how long we wait, the client won't reconnect:
+        time.sleep(2)
+        self.assertRaises(ClientDisconnected, self._storage.load, '\0'*8, '')
+
 class InvqTests(CommonSetupTearDown):
     invq = 3
 
@@ -783,6 +686,34 @@ class ReconnectionTests(CommonSetupTearDown):
         # Stores should fail here
         self.assertRaises(ReadOnlyError, self._dostore)
 
+    # TODO:  Compare checkReconnectXXX() here to checkReconnection()
+    # further down.  Is the code here hopelessly naive, or is
+    # checkReconnection() overwrought?
+
+    def checkReconnectWritable(self):
+        # A read-write client reconnects to a read-write server
+
+        # Start a client
+        self._storage = self.openClientStorage()
+        # Stores should succeed here
+        self._dostore()
+
+        # Shut down the server
+        self.shutdownServer()
+        self._servers = []
+        # Poll until the client disconnects
+        self.pollDown()
+        # Stores should fail now
+        self.assertRaises(ClientDisconnected, self._dostore)
+
+        # Restart the server
+        self.startServer(create=0)
+        # Poll until the client connects
+        self.pollUp()
+        # Stores should succeed here
+        self._dostore()
+        self._storage.close()
+
     def checkReconnectReadOnly(self):
         # A read-only client reconnects from a read-write to a
         # read-only server
@@ -939,6 +870,98 @@ class ReconnectionTests(CommonSetupTearDown):
         perstorage.close()
         self._storage.close()
 
+    def checkDisconnectedAbort(self):
+        self._storage = self.openClientStorage()
+        self._dostore()
+        oids = [self._storage.new_oid() for i in range(5)]
+        txn = Transaction()
+        self._storage.tpc_begin(txn)
+        for oid in oids:
+            data = zodb_pickle(MinPO(oid))
+            self._storage.store(oid, None, data, '', txn)
+        self.shutdownServer()
+        self.assertRaises(ClientDisconnected, self._storage.tpc_vote, txn)
+        self._storage.tpc_abort(txn)
+        self.startServer(create=0)
+        self._storage._wait()
+        self._dostore()
+
+        # This test is supposed to cover the following error, although
+        # I don't have much confidence that it does.  The likely
+        # explanation for the error is that the _tbuf contained
+        # objects that weren't in the _seriald, because the client was
+        # interrupted waiting for tpc_vote() to return.  When the next
+        # transaction committed, it tried to do something with the
+        # bogus _tbuf entries.  The explanation is wrong/incomplete,
+        # because tpc_begin() should clear the _tbuf.
+
+        # 2003-01-15T15:44:19 ERROR(200) ZODB A storage error occurred
+        # in the last phase of a two-phase commit.  This shouldn't happen.
+
+        # Traceback (innermost last):
+        # Module ZODB.Transaction, line 359, in _finish_one
+        # Module ZODB.Connection, line 691, in tpc_finish
+        # Module ZEO.ClientStorage, line 679, in tpc_finish
+        # Module ZEO.ClientStorage, line 709, in _update_cache
+        # KeyError: ...
+
+
+    def checkReconnection(self):
+        # Check that the client reconnects when a server restarts.
+
+        self._storage = self.openClientStorage()
+        oid = self._storage.new_oid()
+        obj = MinPO(12)
+        self._dostore(oid, data=obj)
+        logging.info("checkReconnection(): About to shutdown server")
+        self.shutdownServer()
+        logging.info("checkReconnection(): About to restart server")
+        self.startServer(create=0)
+        oid = self._storage.new_oid()
+        obj = MinPO(12)
+        while 1:
+            try:
+                self._dostore(oid, data=obj)
+                break
+            except ClientDisconnected:
+                # Maybe the exception mess is better now
+                logging.info("checkReconnection(): Error after"
+                             " server restart; retrying.", exc_info=True)
+                transaction.abort()
+            # Give the other thread a chance to run.
+            time.sleep(0.1)
+        logging.info("checkReconnection(): finished")
+        self._storage.close()
+
+    def checkMultipleServers(self):
+        # Crude test-- just start two servers and do a commit at each one.
+
+        self._newAddr()
+        self._storage = self.openClientStorage('test', 100000)
+        self._dostore()
+        self.shutdownServer(index=0)
+
+        # When we start the second server, we use file data file from
+        # the original server so tha the new server is a replica of
+        # the original.  We need this becaise ClientStorage won't use
+        # a server if the server's last transaction is earlier than
+        # what the client has seen.
+        self.startServer(index=1, path=self.file+'.0', create=False)
+
+        # If we can still store after shutting down one of the
+        # servers, we must be reconnecting to the other server.
+
+        did_a_store = 0
+        for i in range(10):
+            try:
+                self._dostore()
+                did_a_store = 1
+                break
+            except ClientDisconnected:
+                time.sleep(0.5)
+        self.assert_(did_a_store)
+        self._storage.close()
+
 class TimeoutTests(CommonSetupTearDown):
     timeout = 1
 

src/ZEO/tests/zeo-fan-out.test

@@ -4,7 +4,7 @@ ZEO Fan Out
 We should be able to set up ZEO servers with ZEO clients.  Let's see
 if we can make it work.
 
-We'll use some helper functions.  The first is a helpter that starts
+We'll use some helper functions.  The first is a helper that starts
 ZEO servers for us and another one that picks ports.
 
 We'll start the first server:
@@ -13,7 +13,8 @@ We'll start the first server:
     >>> port0 = ZEO.tests.testZEO.get_port()
     >>> zconf0 = ZEO.tests.forker.ZEOConfig(('', port0))
     >>> zport0, adminaddr0, pid0, path0 = ZEO.tests.forker.start_zeo_server(
-    ...    '<filestorage 1>\n  path fs\n</filestorage>\n', zconf0, port0)
+    ...    '<filestorage 1>\n  path fs\n</filestorage>\n', zconf0,
+    ...    port0, keep=1)
 
 
 Then we''ll start 2 others that use this one:
@@ -56,13 +57,6 @@ And some databases and connections around these:
     >>> r2
     {}
 
-    >>> db2 = DB(cs2)
-    >>> tm2 = transaction.TransactionManager()
-    >>> c2 = db2.open(transaction_manager=tm2)
-    >>> r2 = c2.root()
-    >>> r2
-    {}
-
 If we update c1, we'll eventually see the change in c2:
 
     >>> import persistent.mapping