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https://issues.apache.org/jira/browse/FLINK-9513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16523197#comment-16523197
 ] 

ASF GitHub Bot commented on FLINK-9513:
---------------------------------------

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.


> Wrap state binder with TTL logic
> --------------------------------
>
>                 Key: FLINK-9513
>                 URL: https://issues.apache.org/jira/browse/FLINK-9513
>             Project: Flink
>          Issue Type: Sub-task
>          Components: State Backends, Checkpointing
>    Affects Versions: 1.6.0
>            Reporter: Andrey Zagrebin
>            Assignee: Andrey Zagrebin
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.6.0
>
>
> The main idea is to wrap user state value with a class holding the value and 
> the expiration timestamp (maybe meta data in future) and use the new object 
> as a value in the existing implementations:
> {code:java}
> class TtlValue<V> {
>   V value;
>   long expirationTimestamp;
> }
> {code}
> The original state binder factory is wrapped with TtlStateBinder if TTL is 
> enabled:
> {code:java}
> state = ttlConfig.updateType == DISABLED ?
>  bind(binder) : bind(new TtlStateBinder(binder, timerService));
> {code}
> TtlStateBinder decorates the states produced by the original binder with TTL 
> logic wrappers and adds TtlValue serialisation logic:
> {code:java}
> TtlStateBinder {
>     StateBinder binder;
>     ProcessingTimeProvier timeProvider; // System.currentTimeMillis()
>     <V> TtlValueState<V> createValueState(valueDesc) {
>          serializer = new TtlValueSerializer(valueDesc.getSerializer);
>          ttlValueDesc = new ValueDesc(serializer, ...);
>          // or implement custom TypeInfo
>          originalStateWithTtl = binder.createValueState(valueDesc);
>          return new TtlValueState(originalStateWithTtl, timeProvider);
>     }
>       // List, Map, ...
> }
> {code}
> TTL serializer should add expiration timestamp



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