[FLINK-11287] RocksDBListState should use actual registered state serializer instead of serializer provided by descriptor

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Component/s: Runtime / State Backends
• Labels: pull-request-available
• Assignee: Tzu-Li (Gordon) Tai
• Reporter: Tzu-Li (Gordon) Tai
• Created: 08/Jan/19 14:25
• Updated: 09/Jan/19 12:04
• Resolved: 09/Jan/19 12:04

Description

Currently, when creating a RocksDBListState, the element serializer wrapped by the RocksDBListState is retrieved from the state descriptor:

static <E, K, N, SV, S extends State, IS extends S> IS create(
    StateDescriptor<S, SV> stateDesc,
    Tuple2<ColumnFamilyHandle, RegisteredKeyValueStateBackendMetaInfo<N, SV>> registerResult,
    RocksDBKeyedStateBackend<K> backend) {

    return (IS) new RocksDBListState<>(
        registerResult.f0,
        registerResult.f1.getNamespaceSerializer(),
        (TypeSerializer<List<E>>) registerResult.f1.getStateSerializer(),
        (List<E>) stateDesc.getDefaultValue(),
        ((ListStateDescriptor<E>) stateDesc).getElementSerializer(), // incorrect
        backend);
}

This is incorrect, since new serializers retrieved from state descriptors have not been checked for compatibility with restored state.

Instead, the element serializer should be retrieved from the register result, which contains the actual state serializer registered in the state backend for state access (and has already been checked for compatibility / reconfigured appropriately).

Issue Links

• links to: GitHub Pull Request #7434