[CASSANDRA-14439] ClassCastException with mixed 1.2.18 + 2.0.17 environment

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Won't Fix
• Component/s: Legacy/Core
• Labels: easyfix

Environment

Mixed 1.2.18  + 2.0.17 environment, used temporarily during incremental migration process.

• Severity: Low
• Since Version: 2.0.0
• Assignee: Dariusz Cieslak
• Reporter: Dariusz Cieslak

Authors

Dariusz Cieslak

Reviewers

Michael Semb Wever

• Created: 08/May/18 12:14
• Updated: 16/Apr/19 09:29
• Resolved: 11/Apr/19 12:23

Description

During mixed versions tests I've discovered that mixed 1.2.18  + 2.0.17 environment gives the following exception on 2.0.17 node:

java.lang.ClassCastException: org.apache.cassandra.db.SliceByNamesReadCommand cannot be cast to org.apache.cassandra.db.SliceFromReadCommand
at org.apache.cassandra.db.SliceFromReadCommandSerializer.serializedSize(SliceFromReadCommand.java:242)
at org.apache.cassandra.db.ReadCommandSerializer.serializedSize(ReadCommand.java:204)
at org.apache.cassandra.db.ReadCommandSerializer.serializedSize(ReadCommand.java:134)
at org.apache.cassandra.net.MessageOut.serialize(MessageOut.java:116)
at org.apache.cassandra.net.OutboundTcpConnection.writeInternal(OutboundTcpConnection.java:251)
at org.apache.cassandra.net.OutboundTcpConnection.writeConnected(OutboundTcpConnection.java:203)
at org.apache.cassandra.net.OutboundTcpConnection.run(OutboundTcpConnection.java:151)

The exception is caused by inconsistent commandType handling in ReadCommandSerializer(),

        out.writeByte(newCommand.commandType.serializedValue);
        switch (command.commandType) /// <----------- WHY NOT newCommand.commandType -- DCI ???
        {
            case GET_BY_NAMES:
                SliceByNamesReadCommand.serializer.serialize(newCommand, superColumn, out, version);
                break;
            case GET_SLICES:
                SliceFromReadCommand.serializer.serialize(newCommand, superColumn, out, version);
                break;
            default:
                throw new AssertionError();
        }

Proposed fix (also attached as a patch):

diff --git a/src/java/org/apache/cassandra/db/ReadCommand.java b/src/java/org/apache/cassandra/db/ReadCommand.java
index cadcd7d..f2153e8 100644
--- a/src/java/org/apache/cassandra/db/ReadCommand.java
+++ b/src/java/org/apache/cassandra/db/ReadCommand.java
@@ -153,7 +153,7 @@ class ReadCommandSerializer implements IVersionedSerializer<ReadCommand>
         }
 
         out.writeByte(newCommand.commandType.serializedValue);
-        switch (command.commandType)
+        switch (newCommand.commandType)
         {
             case GET_BY_NAMES:
                 SliceByNamesReadCommand.serializer.serialize(newCommand, superColumn, out, version);
@@ -196,7 +196,7 @@ class ReadCommandSerializer implements IVersionedSerializer<ReadCommand>
             }
         }
 
-        switch (command.commandType)
+        switch (newCommand.commandType)
         {
             case GET_BY_NAMES:
                 return 1 + SliceByNamesReadCommand.serializer.serializedSize(newCommand, superColumn, version);

Issue Links

• is related to: CASSANDRA-14414 Errors in Supercolumn support in 2.0 upgrade