Github user sihuazhou commented on a diff in the pull request:
https://github.com/apache/flink/pull/6196#discussion_r198014886
--- Diff:
flink-core/src/main/java/org/apache/flink/api/common/typeutils/CompositeSerializer.java
---
@@ -0,0 +1,204 @@
+package org.apache.flink.api.common.typeutils;
+
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+import org.apache.flink.util.Preconditions;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+/**
+ * Base class for composite serializers.
+ *
+ * <p>This class serializes a list of objects
+ *
+ * @param <T> type of custom serialized value
+ */
+@SuppressWarnings("unchecked")
+public abstract class CompositeSerializer<T> extends TypeSerializer<T> {
+ private final List<TypeSerializer> originalSerializers;
+
+ protected CompositeSerializer(List<TypeSerializer> originalSerializers)
{
+ Preconditions.checkNotNull(originalSerializers);
+ this.originalSerializers = originalSerializers;
+ }
+
+ protected abstract T composeValue(List values);
+
+ protected abstract List decomposeValue(T v);
+
+ protected abstract CompositeSerializer<T>
createSerializerInstance(List<TypeSerializer> originalSerializers);
+
+ private T composeValueInternal(List values) {
+ Preconditions.checkArgument(values.size() ==
originalSerializers.size());
+ return composeValue(values);
+ }
+
+ private List decomposeValueInternal(T v) {
+ List values = decomposeValue(v);
+ Preconditions.checkArgument(values.size() ==
originalSerializers.size());
+ return values;
+ }
+
+ private CompositeSerializer<T>
createSerializerInstanceInternal(List<TypeSerializer> originalSerializers) {
+ Preconditions.checkArgument(originalSerializers.size() ==
originalSerializers.size());
+ return createSerializerInstance(originalSerializers);
+ }
+
+ @Override
+ public CompositeSerializer<T> duplicate() {
+ return
createSerializerInstanceInternal(originalSerializers.stream()
+ .map(TypeSerializer::duplicate)
+ .collect(Collectors.toList()));
+ }
+
+ @Override
+ public boolean isImmutableType() {
+ return
originalSerializers.stream().allMatch(TypeSerializer::isImmutableType);
+ }
+
+ @Override
+ public T createInstance() {
+ return composeValueInternal(originalSerializers.stream()
+ .map(TypeSerializer::createInstance)
+ .collect(Collectors.toList()));
+ }
+
+ @Override
+ public T copy(T from) {
+ List originalValues = decomposeValueInternal(from);
+ return composeValueInternal(
+ IntStream.range(0, originalSerializers.size())
+ .mapToObj(i ->
originalSerializers.get(i).copy(originalValues.get(i)))
+ .collect(Collectors.toList()));
+ }
+
+ @Override
+ public T copy(T from, T reuse) {
+ List originalFromValues = decomposeValueInternal(from);
+ List originalReuseValues = decomposeValueInternal(reuse);
+ return composeValueInternal(
+ IntStream.range(0, originalSerializers.size())
+ .mapToObj(i ->
originalSerializers.get(i).copy(originalFromValues.get(i),
originalReuseValues.get(i)))
+ .collect(Collectors.toList()));
+ }
+
+ @Override
+ public int getLength() {
+ return originalSerializers.stream().allMatch(s -> s.getLength()
>= 0) ?
+
originalSerializers.stream().mapToInt(TypeSerializer::getLength).sum() : -1;
+ }
+
+ @Override
+ public void serialize(T record, DataOutputView target) throws
IOException {
+ List originalValues = decomposeValueInternal(record);
+ for (int i = 0; i < originalSerializers.size(); i++) {
+
originalSerializers.get(i).serialize(originalValues.get(i), target);
--- End diff --
If `originalSerializers` or the `originalValues` is a type of something
like `LinkedList`, then the `originalSerializers.get(i)` and
`originalValues.get(i)` will get a very poor performance. I think we might
should use the `iterator` here.
---
