openinx commented on a change in pull request #1793: URL: https://github.com/apache/iceberg/pull/1793#discussion_r535970149
########## 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."); + Preconditions.checkArgument( + options.endSnapshotId() == null, "The streaming reader does not support using end snapshot id."); + this.tableLoader = tableLoader; + this.projectedSchema = projectedSchema; + this.filterExpressions = filterExpressions; + this.options = options; + } + + @Override + public void initializeState(FunctionInitializationContext context) throws Exception { + snapshotIdState = context.getOperatorStateStore().getListState( + new ListStateDescriptor<>( + "snapshot-id-state", + LongSerializer.INSTANCE)); + tableLoader.open(); + table = tableLoader.loadTable(); + if (context.isRestored()) { + LOG.info("Restoring state for the {}.", getClass().getSimpleName()); + startSnapshotId = snapshotIdState.get().iterator().next(); + } else { + Long optionStartSnapshot = options.startSnapshotId(); + if (optionStartSnapshot != null) { + if (!SnapshotUtil.ancestorOf(table, table.currentSnapshot().snapshotId(), optionStartSnapshot)) { + throw new IllegalStateException("The option start-snapshot-id " + optionStartSnapshot + + " is not an ancestor of the current snapshot"); + } + + startSnapshotId = optionStartSnapshot; + } else { + startSnapshotId = DUMMY_START_SNAPSHOT_ID; + } + } + } + + @Override + public void run(SourceContext<FlinkInputSplit> ctx) throws Exception { + checkpointLock = ctx.getCheckpointLock(); + while (isRunning) { + synchronized (checkpointLock) { + monitorAndForwardSplits(ctx); Review comment: Think about this again, it's true that we need to have a `isRunning` checking inside the `synchronized` block. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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