[jira] [Created] (FLINK-6190) Write "Serializer Configurations" metainfo along with state

[Shang Yuanchun (Jira)]

Tzu-Li (Gordon) Tai created FLINK-6190:
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             Summary: Write "Serializer Configurations" metainfo along with state
                 Key: FLINK-6190
                 URL: https://issues.apache.org/jira/browse/FLINK-6190
             Project: Flink
          Issue Type: Sub-task
          Components: State Backends, Checkpointing, Type Serialization System
            Reporter: Tzu-Li (Gordon) Tai
            Assignee: Tzu-Li (Gordon) Tai


In order for serializers to be able to be reconfigured on restore, we need knowledge of the previous serializer configurations, e.g. what types were registered, with which specific / default serializers, and especially for Kryo, the order they were registered.

For this, we will need serializer configuration metainfo to be self-contained within the written state.

For the implementation, we propose the following:

- Have a new separate `SerializersConfig` class that is extracted from `ExecutionConfig`. This new class should contain only the serializer-related configurations (e.g., `registeredKryoTypes`, `registeredPojoTypes`, etc.).

- Introduce `SerializersConfigSerializationProxy`, which is in charge of serializing the current `SerializersConfig` when writing state to streams. This proxy defines the the serialized format of serializer configurations, therefore should  be a `VersionedIOReadableWritable` as we may change the format / information written in the future.

- Add `SerializersConfigSerializationProxy` into state backends serialization proxies (e.g. `KeyedBackendSerializationProxy`) so that the serializer configuration is written into state. Need to additionally make sure backwards compatibility of previous-version backend serialization proxies.



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