openinx commented on a change in pull request #1793: URL: https://github.com/apache/iceberg/pull/1793#discussion_r535898916
########## File path: flink/src/main/java/org/apache/iceberg/flink/source/StreamingMonitorFunction.java ########## @@ -0,0 +1,172 @@ +/* + * 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.iceberg.flink.source; + +import java.io.IOException; +import java.io.UncheckedIOException; +import java.util.List; +import org.apache.flink.api.common.state.ListState; +import org.apache.flink.api.common.state.ListStateDescriptor; +import org.apache.flink.api.common.typeutils.base.LongSerializer; +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.iceberg.Schema; +import org.apache.iceberg.Snapshot; +import org.apache.iceberg.Table; +import org.apache.iceberg.expressions.Expression; +import org.apache.iceberg.flink.TableLoader; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.util.SnapshotUtil; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * This is the single (non-parallel) monitoring task which takes a {@link FlinkInputFormat}, + * it is responsible for: + * + * <ol> + * <li>Monitoring snapshots of the Iceberg table.</li> + * <li>Creating the {@link FlinkInputSplit splits} corresponding to the incremental 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 StreamingReaderOperator} + * which can have parallelism greater than one. + */ +public class StreamingMonitorFunction extends RichSourceFunction<FlinkInputSplit> implements CheckpointedFunction { + + private static final long serialVersionUID = 1L; + + private static final Logger LOG = LoggerFactory.getLogger(StreamingMonitorFunction.class); + + private static final long DUMMY_START_SNAPSHOT_ID = -1; + + private final TableLoader tableLoader; + private final Schema projectedSchema; + private final List<Expression> filterExpressions; + private final ScanContext options; + + private volatile boolean isRunning = true; + private transient Object checkpointLock; + private transient Table table; + private transient ListState<Long> snapshotIdState; + private transient long startSnapshotId; + + public StreamingMonitorFunction(TableLoader tableLoader, Schema projectedSchema, List<Expression> filterExpressions, + ScanContext options) { + Preconditions.checkArgument( + options.snapshotId() == null && options.asOfTimestamp() == null, + "The streaming reader does not support using snapshot-id or as-of-timestamp to select the table snapshot."); Review comment: If user did not provide a `start-snapshot-id`, then this function will use the snapshot id (it's a `DUMMY_START_SNAPSHOT_ID` in code) before `current` snapshot as the `start-snapshot-id`. So we are allowed to pass `null` `start-snapshot-id` but are not allowed to pass non-null `end-snapshot-id`. ---------------------------------------------------------------- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
