Github user sihuazhou commented on a diff in the pull request:
https://github.com/apache/flink/pull/6186#discussion_r196996839
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/state/ttl/TtlListState.java
---
@@ -0,0 +1,171 @@
+/*
+ * 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.ttl;
+
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.runtime.state.internal.InternalListState;
+import org.apache.flink.util.Preconditions;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+/**
+ * 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, List<T>, List<TtlValue<T>>, InternalListState<K,
N, TtlValue<T>>>
+ implements InternalListState<K, N, T> {
+ TtlListState(
+ InternalListState<K, N, TtlValue<T>> originalState,
+ TtlConfig config,
+ TtlTimeProvider timeProvider,
+ TypeSerializer<List<T>> valueSerializer) {
+ super(originalState, config, timeProvider, valueSerializer);
+ }
+
+ @Override
+ public void update(List<T> values) throws Exception {
+ updateInternal(values);
+ }
+
+ @Override
+ public void addAll(List<T> values) throws Exception {
+ Preconditions.checkNotNull(values, "List of values to add
cannot be null.");
+ original.addAll(withTs(values));
+ }
+
+ @Override
+ public Iterable<T> get() throws Exception {
+ Iterable<TtlValue<T>> ttlValue = original.get();
+ ttlValue = ttlValue == null ? Collections.emptyList() :
ttlValue;
+ if (updateTsOnRead) {
+ List<TtlValue<T>> collected = collect(ttlValue);
--- End diff --
In this block, we need to iterate the `ttlValue` twice, one for `collect()`
and one for `updateTs()`. If we could make the updateTs to accept `Iterable` as
the argument, then we can avoiding the `collect()` here, this way we only need
to iterate the `ttlValue` once.
---
