danny0405 commented on a change in pull request #2640: URL: https://github.com/apache/hudi/pull/2640#discussion_r590940541
########## File path: hudi-flink/src/main/java/org/apache/hudi/operator/StreamReadMonitoringFunction.java ########## @@ -0,0 +1,324 @@ +/* + * 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.hudi.operator; + +import org.apache.hudi.common.fs.FSUtils; +import org.apache.hudi.common.model.HoodieLogFile; +import org.apache.hudi.common.table.HoodieTableMetaClient; +import org.apache.hudi.common.table.timeline.HoodieInstant; +import org.apache.hudi.common.table.timeline.HoodieTimeline; +import org.apache.hudi.common.table.view.HoodieTableFileSystemView; +import org.apache.hudi.common.util.Option; +import org.apache.hudi.common.util.ValidationUtils; +import org.apache.hudi.exception.HoodieException; +import org.apache.hudi.source.format.FilePathUtils; +import org.apache.hudi.source.format.mor.InstantRange; +import org.apache.hudi.source.format.mor.MergeOnReadInputSplit; +import org.apache.hudi.util.StreamerUtil; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.api.common.state.ListState; +import org.apache.flink.api.common.state.ListStateDescriptor; +import org.apache.flink.api.common.typeutils.base.StringSerializer; +import org.apache.flink.configuration.Configuration; +import org.apache.flink.core.fs.Path; +import org.apache.flink.runtime.state.FunctionInitializationContext; +import org.apache.flink.runtime.state.FunctionSnapshotContext; +import org.apache.flink.streaming.api.checkpoint.CheckpointedFunction; +import org.apache.flink.streaming.api.functions.source.RichSourceFunction; +import org.apache.flink.streaming.api.functions.source.SourceFunction; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collection; +import java.util.List; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.stream.Collectors; + +import static org.apache.hudi.common.table.timeline.HoodieTimeline.GREATER_THAN; +import static org.apache.hudi.common.table.timeline.HoodieTimeline.GREATER_THAN_OR_EQUALS; + +/** + * This is the single (non-parallel) monitoring task which takes a {@link MergeOnReadInputSplit} + * , it is responsible for: + * + * <ol> + * <li>Monitoring a user-provided hoodie table path.</li> + * <li>Deciding which files(or split) should be further read and processed.</li> + * <li>Creating the {@link MergeOnReadInputSplit splits} corresponding to those files.</li> + * <li>Assigning them to downstream tasks for further processing.</li> + * </ol> + * + * <p>The splits to be read are forwarded to the downstream {@link StreamReadOperator} + * which can have parallelism greater than one. + * + * <p><b>IMPORTANT NOTE: </b> Splits are forwarded downstream for reading in ascending instant commits time order, + * in each downstream task, the splits are also read in receiving sequence. We do not ensure split consuming sequence + * among the downstream tasks. + */ +public class StreamReadMonitoringFunction Review comment: `ContinuousFileMonitoringFunction` works based on `FileInputSplit` but this function works based on `MergeOnReadInputSplit`, `ContinuousFileMonitoringFunction` needs the input format has the ability to book-keep the consuming offset for each file which `MergeOnReadInputFormat` does not have. In a word, `StreamReadMonitoringFunction` is more simple code (has no complex state machine in the code) and also works well. ---------------------------------------------------------------- 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: [email protected]
