tweise commented on a change in pull request #15924:
URL: https://github.com/apache/flink/pull/15924#discussion_r672782651
##########
File path:
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/source/hybrid/HybridSource.java
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@@ -110,69 +106,64 @@ public Boundedness getBoundedness() {
@Override
public SimpleVersionedSerializer<HybridSourceSplit> getSplitSerializer() {
- // List<SimpleVersionedSerializer<SourceSplit>> serializers = new
ArrayList<>();
- // TODO: serializers are created on demand as underlying sources are
created during switch
- // sources.forEach(t ->
serializers.add(castSerializer(t.source.getSplitSerializer())));
return new HybridSourceSplitSerializer(switchedSources);
}
@Override
public SimpleVersionedSerializer<HybridSourceEnumeratorState>
getEnumeratorCheckpointSerializer() {
- List<SimpleVersionedSerializer<Object>> serializers = new
ArrayList<>();
- sources.forEach(
- t ->
serializers.add(castSerializer(t.source.getEnumeratorCheckpointSerializer())));
- return new HybridSourceEnumeratorStateSerializer(serializers);
- }
-
- private static <T> SimpleVersionedSerializer<T> castSerializer(
- SimpleVersionedSerializer<? extends T> s) {
- @SuppressWarnings("rawtypes")
- SimpleVersionedSerializer s1 = s;
- return s1;
+ return new HybridSourceEnumeratorStateSerializer(switchedSources);
}
/**
- * Callback for switch time customization of the underlying source,
typically to dynamically set
- * a start position from previous enumerator end state.
+ * Factory for underlying sources of {@link HybridSource}.
*
- * <p>Requires the ability to augment the existing source (or clone and
modify). Provides the
- * flexibility to set start position in any way a source allows, in a
source specific way.
- * Future convenience could be built on top of it, for example an
implementation recognizes
- * optional interfaces.
+ * <p>This factory permits building of a source at graph construction time
or deferred at switch
+ * time. Provides the ability to set a start position in any way a
specific source allows.
+ * Future convenience could be built on top of it, for example a default
implementation that
+ * recognizes optional interfaces to transfer position in a common format.
*
* <p>Called when the current enumerator has finished and before the next
enumerator is created.
- * The enumerator end state can thus be used to set the next source's
start start position.
+ * The enumerator end state can thus be used to set the next source's
start start position. Only
+ * required for dynamic position transfer at time of switching.
*
- * <p>Only required for dynamic position transfer at time of switching,
otherwise source can be
- * preconfigured with a start position during job submission.
+ * <p>If start position is known at jib submission, the source can be
constructed in the entry
+ * point and simply wrapped into the factory, providing the benefit of
validation during
+ * submission.
*/
- public interface SourceConfigurer<SourceT extends Source, FromEnumT
extends SplitEnumerator>
+ public interface SourceFactory<T, SourceT extends Source, FromEnumT
extends SplitEnumerator>
extends Serializable {
- SourceT configure(SourceT source, FromEnumT enumerator);
+ SourceT create(FromEnumT enumerator);
Review comment:
@becketqin thank you for the detailed analysis. I agree that there
should be a way to extract the end position from `FileSource`. It's mentioned
on the FLIP that we would like to keep this work separate, so that we can also
think about a potential uniform end position format. Meanwhile `SourceFactory`
and `SourceSwitchContext` provide the mechanism to solve this in a source
specific way. We intend to use it internally with a custom source and other
sources may provide their own way to access the end position. I hope that the
augmented examples make this more clear and the intended boundary for this PR
also makes sense? CC: @AHeise
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