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https://issues.apache.org/jira/browse/FLINK-8841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16453672#comment-16453672
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ASF GitHub Bot commented on FLINK-8841:
---------------------------------------
Github user StefanRRichter commented on a diff in the pull request:
https://github.com/apache/flink/pull/5910#discussion_r184304664
--- Diff:
flink-core/src/main/java/org/apache/flink/util/InstantiationUtil.java ---
@@ -221,6 +226,52 @@ protected ObjectStreamClass readClassDescriptor()
throws IOException, ClassNotFo
}
}
+ /**
+ * A mapping between the full path of a deprecated serializer and its
equivalent.
+ * These mappings are hardcoded and fixed.
+ *
+ * <p>IMPORTANT: mappings can be removed after 1 release as there will
be a "migration path".
+ * As an example, a serializer is removed in 1.5-SNAPSHOT, then the
mapping should be added for 1.5,
+ * and it can be removed in 1.6, as the path would be Flink-{< 1.5} ->
Flink-1.5 -> Flink-{>= 1.6}.
+ */
+ private enum MigrationUtil {
+
+ // To add a new mapping just pick a name and add an entry as
the following:
+
+ GENERIC_DATA_ARRAY_SERIALIZER(
+ "org.apache.avro.generic.GenericData$Array",
+
ObjectStreamClass.lookup(KryoRegistrationSerializerConfigSnapshot.DummyRegisteredClass.class)),
+ HASH_MAP_SERIALIZER(
+
"org.apache.flink.runtime.state.HashMapSerializer",
+ ObjectStreamClass.lookup(MapSerializer.class));
// added in 1.5
+
+ /** An internal unmoddifiable map containing the mappings
between deprecated and new serialzers. */
+ private static final Map<String, ObjectStreamClass>
equivalenceMap = Collections.unmodifiableMap(initMap());
+
+ /** The full name of the class of the old serializer. */
+ private final String oldSerializer;
+
+ /** The serialization descriptor of the class of the new
serializer. */
+ private final ObjectStreamClass newSerializer;
--- End diff --
Here I suggest to add `StreamClass` to the name.
> Duplicate MapSerializer and HashMapSerializer.
> ----------------------------------------------
>
> Key: FLINK-8841
> URL: https://issues.apache.org/jira/browse/FLINK-8841
> Project: Flink
> Issue Type: Bug
> Components: State Backends, Checkpointing, Type Serialization System
> Affects Versions: 1.5.0
> Reporter: Kostas Kloudas
> Assignee: Kostas Kloudas
> Priority: Major
> Fix For: 1.5.0
>
>
> Currently there are two class MapSerializer and HashMapSerializer whose code
> is the same with the only difference being that one includes elements of type
> Map and the other HashMap.
> In addition, these two were merged on the same commit.
> I would like to remove the HashMapSerializer. I already created a branch
> without the HashMapSerialzer and nothing seems to be failing on Travis. The
> reasons why I hesitate to do it, is because I am not sure if this may create
> problems with Backwards Compatibility.
> [~xiaogang.sxg] could you elaborate a bit on why they were both added and if
> there is any danger in removing the HashMapSerializer?
> Also [~StephanEwen] and [~stefanrichte...@gmail.com] it is worth having a
> look and if you are ok, I can remove the redundant serializer.
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