Zakelly commented on code in PR #25515: URL: https://github.com/apache/flink/pull/25515#discussion_r1820059326
########## flink-runtime/src/main/java/org/apache/flink/runtime/state/v2/ttl/TtlListState.java: ########## @@ -0,0 +1,207 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.runtime.state.v2.ttl; + +import org.apache.flink.api.common.state.v2.StateFuture; +import org.apache.flink.api.common.state.v2.StateIterator; +import org.apache.flink.runtime.state.ttl.TtlStateContext; +import org.apache.flink.runtime.state.ttl.TtlUtils; +import org.apache.flink.runtime.state.ttl.TtlValue; +import org.apache.flink.runtime.state.v2.internal.InternalListState; +import org.apache.flink.util.Preconditions; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.Iterator; +import java.util.List; +import java.util.NoSuchElementException; +import java.util.function.Consumer; +import java.util.function.Function; + +/** + * This class wraps list state with TTL logic. + * + * @param <K> The type of key the state is associated to + * @param <N> The type of the namespace + * @param <T> Type of the user entry value of state with TTL + */ +class TtlListState<K, N, T> + extends AbstractTtlState<K, N, T, TtlValue<T>, InternalListState<K, N, TtlValue<T>>> + implements InternalListState<K, N, T> { + + protected TtlListState( + TtlStateContext<InternalListState<K, N, TtlValue<T>>, T> ttlStateContext) { + super(ttlStateContext); + } + + @Override + public StateFuture<Void> asyncUpdate(List<T> values) { + Preconditions.checkNotNull(values, "List of values to add cannot be null."); + return original.asyncUpdate(withTs(values)); + } + + @Override + public StateFuture<Void> asyncAddAll(List<T> values) { + Preconditions.checkNotNull(values, "List of values to add cannot be null."); + return original.asyncAddAll(withTs(values)); + } + + @Override + public StateFuture<StateIterator<T>> asyncGet() { + // 1. The timestamp of elements in list state isn't updated when get even if updateTsOnRead + // is true. + // 2. we don't clear state here cause forst is LSM-tree based. + return original.asyncGet().thenApply(stateIter -> new AsyncIteratorWrapper(stateIter)); + } + + @Override + public StateFuture<Void> asyncAdd(T value) { + return original.asyncAdd(value == null ? null : wrapWithTs(value)); + } + + @Override + public Iterable<T> get() { + Iterable<TtlValue<T>> ttlValue = original.get(); + ttlValue = ttlValue == null ? Collections.emptyList() : ttlValue; + final Iterable<TtlValue<T>> finalResult = ttlValue; + return () -> new IteratorWithCleanup(finalResult.iterator()); + } + + @Override + public void add(T value) { + original.add(value == null ? null : wrapWithTs(value)); + } + + @Override + public void update(List<T> values) { + Preconditions.checkNotNull(values, "List of values to add cannot be null."); + original.update(withTs(values)); + } + + @Override + public void addAll(List<T> values) { + Preconditions.checkNotNull(values, "List of values to add cannot be null."); + original.addAll(withTs(values)); + } + + private <E> List<E> collect(Iterable<E> iterable) { + if (iterable instanceof List) { + return (List<E>) iterable; + } else { + List<E> list = new ArrayList<>(); + for (E element : iterable) { + list.add(element); + } + return list; + } + } + + private List<TtlValue<T>> withTs(List<T> values) { + long currentTimestamp = timeProvider.currentTimestamp(); + List<TtlValue<T>> withTs = new ArrayList<>(values.size()); + for (T value : values) { + Preconditions.checkNotNull(value, "You cannot have null element in a ListState."); + withTs.add(TtlUtils.wrapWithTs(value, currentTimestamp)); + } + return withTs; + } + + private class IteratorWithCleanup implements Iterator<T> { + private final Iterator<TtlValue<T>> originalIterator; + private boolean anyUnexpired = false; + private boolean uncleared = true; + private T nextUnexpired = null; + + private IteratorWithCleanup(Iterator<TtlValue<T>> ttlIterator) { + this.originalIterator = ttlIterator; + } + + @Override + public boolean hasNext() { + findNextUnexpired(); + cleanupIfEmpty(); + return nextUnexpired != null; + } + + private void cleanupIfEmpty() { + boolean endOfIter = !originalIterator.hasNext() && nextUnexpired == null; + if (uncleared && !anyUnexpired && endOfIter) { + original.clear(); + uncleared = false; + } + } + + @Override + public T next() { + if (hasNext()) { + T result = nextUnexpired; + nextUnexpired = null; + return result; + } + throw new NoSuchElementException(); + } + + // Once a null element is encountered, the subsequent elements will no longer be returned. + private void findNextUnexpired() { + while (nextUnexpired == null && originalIterator.hasNext()) { + TtlValue<T> ttlValue = originalIterator.next(); + if (ttlValue == null) { + break; + } + boolean unexpired = !expired(ttlValue); + if (unexpired) { + anyUnexpired = true; + } + if (unexpired || returnExpired) { + nextUnexpired = ttlValue.getUserValue(); + } + } + } + } + + private class AsyncIteratorWrapper implements StateIterator<T> { + + private final StateIterator<TtlValue<T>> originalIterator; + + public AsyncIteratorWrapper(StateIterator<TtlValue<T>> originalIterator) { + this.originalIterator = originalIterator; + } + + @Override + public <U> StateFuture<Collection<U>> onNext( + Function<T, StateFuture<? extends U>> iterating) { + Function<TtlValue<T>, StateFuture<? extends U>> ttlIterating = + (item) -> iterating.apply(getElementWithTtlCheck(item)); Review Comment: The `getElementWithTtlCheck` may return `null`, the user-defined `iterating` function should not be invoked in this case? -- This is an automated message from the Apache Git Service. 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