curcur commented on a change in pull request #14943: URL: https://github.com/apache/flink/pull/14943#discussion_r592997531
########## File path: flink-state-backends/flink-statebackend-changelog/src/main/java/org/apache/flink/state/changelog/ChangelogStateBackend.java ########## @@ -0,0 +1,163 @@ +/* + * 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.state.changelog; + +import org.apache.flink.api.common.JobID; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.configuration.IllegalConfigurationException; +import org.apache.flink.configuration.ReadableConfig; +import org.apache.flink.core.fs.CloseableRegistry; +import org.apache.flink.metrics.MetricGroup; +import org.apache.flink.runtime.execution.Environment; +import org.apache.flink.runtime.query.TaskKvStateRegistry; +import org.apache.flink.runtime.state.AbstractKeyedStateBackend; +import org.apache.flink.runtime.state.CheckpointableKeyedStateBackend; +import org.apache.flink.runtime.state.ConfigurableStateBackend; +import org.apache.flink.runtime.state.KeyGroupRange; +import org.apache.flink.runtime.state.KeyedStateHandle; +import org.apache.flink.runtime.state.OperatorStateBackend; +import org.apache.flink.runtime.state.OperatorStateHandle; +import org.apache.flink.runtime.state.StateBackend; +import org.apache.flink.runtime.state.delegate.DelegatingStateBackend; +import org.apache.flink.runtime.state.ttl.TtlTimeProvider; +import org.apache.flink.util.Preconditions; + +import javax.annotation.Nonnull; + +import java.util.Collection; + +/** + * This state backend holds the working state in the underlying delegatedStateBackend, and forwards + * state changes to State Changelog. + */ +public class ChangelogStateBackend implements DelegatingStateBackend, ConfigurableStateBackend { + + private static final long serialVersionUID = 1000L; + + private final StateBackend delegatedStateBackend; + + public ChangelogStateBackend(StateBackend stateBackend) { + this.delegatedStateBackend = Preconditions.checkNotNull(stateBackend); + + Preconditions.checkArgument( + !(stateBackend instanceof ChangelogStateBackend), + "Recursive Delegation on ChangelogStateBackend is not supported."); + } + + @Override + public <K> ChangelogKeyedStateBackend<K> createKeyedStateBackend( Review comment: Not having the full context, I would be a bit hesitant to do so, because the suggested change is made based on the assumption that the default `managedMemoryFraction` to createKeyedStateBackend is always `1.0`. I would prevent hard-coding the default value as such. Or put another way, why we have two different methods in the interface `StateBackend` `createKeyedStateBackend`, and why we do not simply hardcode 1.0 in one of the methods in a similar way as you suggested? I would be cautious to make the change for a safety purpose. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
