[GitHub] [flink] JingsongLi commented on a change in pull request #12004: [FLINK-17434][core][hive] Hive partitioned source support streaming read

[GitBox <gi...@apache.org>]

JingsongLi commented on a change in pull request #12004:
URL: https://github.com/apache/flink/pull/12004#discussion_r422454432



##########
File path: flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/connectors/hive/read/HiveContinuousMonitoringFunction.java
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@@ -0,0 +1,280 @@
+/*
+ * 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.connectors.hive.read;
+
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import org.apache.flink.api.common.typeutils.base.ListSerializer;
+import org.apache.flink.api.common.typeutils.base.LongSerializer;
+import org.apache.flink.api.common.typeutils.base.StringSerializer;
+import org.apache.flink.connectors.hive.HiveTablePartition;
+import org.apache.flink.connectors.hive.HiveTableSource;
+import org.apache.flink.connectors.hive.JobConfWrapper;
+import org.apache.flink.connectors.hive.read.PartitionStrategy.PartitionStrategyFactory;
+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.ContinuousFileReaderOperator;
+import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
+import org.apache.flink.table.catalog.CatalogTable;
+import org.apache.flink.table.catalog.ObjectPath;
+import org.apache.flink.table.catalog.hive.client.HiveShim;
+import org.apache.flink.table.catalog.hive.util.HiveReflectionUtils;
+import org.apache.flink.table.types.DataType;
+import org.apache.flink.util.Preconditions;
+
+import org.apache.hadoop.hive.conf.HiveConf;
+import org.apache.hadoop.hive.metastore.IMetaStoreClient;
+import org.apache.hadoop.hive.metastore.api.Partition;
+import org.apache.hadoop.hive.metastore.api.Table;
+import org.apache.hadoop.mapred.JobConf;
+import org.apache.thrift.TException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Properties;
+import java.util.Set;
+
+/**
+ * This is the single (non-parallel) monitoring task which takes a {@link HiveTableInputFormat},
+ * it is responsible for:
+ *
+ * <ol>
+ *     <li>Monitoring partitions of hive meta store.</li>
+ *     <li>Deciding which partitions should be further read and processed.</li>
+ *     <li>Creating the {@link HiveTableInputSplit splits} corresponding to those partitions.</li>
+ *     <li>Assigning them to downstream tasks for further processing.</li>
+ * </ol>
+ *
+ * <p>The splits to be read are forwarded to the downstream {@link ContinuousFileReaderOperator}
+ * which can have parallelism greater than one.
+ *
+ * <p><b>IMPORTANT NOTE: </b> Splits are forwarded downstream for reading in ascending partition time order,
+ * based on the partition time of the partitions they belong to.
+ */
+public class HiveContinuousMonitoringFunction
+		extends RichSourceFunction<TimestampedHiveInputSplit>
+		implements CheckpointedFunction {
+
+	private static final long serialVersionUID = 1L;
+
+	private static final Logger LOG = LoggerFactory.getLogger(HiveContinuousMonitoringFunction.class);
+
+	/** The parallelism of the downstream readers. */
+	private final int readerParallelism;
+
+	/** The interval between consecutive path scans. */
+	private final long interval;
+
+	private final HiveShim hiveShim;
+
+	private final JobConfWrapper conf;
+
+	private final ObjectPath tablePath;
+
+	private final List<String> partitionKeys;
+
+	private final String[] fieldNames;
+
+	private final DataType[] fieldTypes;
+
+	private final long startupTimestampMillis;
+
+	private final PartitionStrategyFactory partStrategyFactory;
+
+	private volatile boolean isRunning = true;
+
+	/** The maximum partition read time seen so far. */
+	private volatile long currentReadTime;
+
+	private transient PartitionStrategy strategy;
+
+	private transient Object checkpointLock;
+
+	private transient ListState<Long> currReadTimeState;
+
+	private transient ListState<List<List<String>>> distinctPartsState;
+
+	private transient IMetaStoreClient client;
+
+	private transient Properties tableProps;
+
+	private transient String defaultPartitionName;
+
+	private transient Set<List<String>> distinctPartitions;
+
+	public HiveContinuousMonitoringFunction(
+			HiveShim hiveShim,
+			JobConf conf,
+			ObjectPath tablePath,
+			CatalogTable catalogTable,
+			long startupTimestampMillis,
+			PartitionStrategyFactory partStrategyFactory,
+			int readerParallelism,
+			long interval) {
+		this.hiveShim = hiveShim;
+		this.conf = new JobConfWrapper(conf);
+		this.tablePath = tablePath;
+		this.partitionKeys = catalogTable.getPartitionKeys();
+		this.fieldNames = catalogTable.getSchema().getFieldNames();
+		this.fieldTypes = catalogTable.getSchema().getFieldDataTypes();
+		this.startupTimestampMillis = startupTimestampMillis;
+		this.partStrategyFactory = partStrategyFactory;
+
+		this.interval = interval;
+		this.readerParallelism = Math.max(readerParallelism, 1);
+		this.currentReadTime = Long.MIN_VALUE;
+	}
+
+	@Override
+	public void initializeState(FunctionInitializationContext context) throws Exception {
+		this.strategy = partStrategyFactory.createStrategy(getRuntimeContext().getUserCodeClassLoader());
+
+		this.currReadTimeState = context.getOperatorStateStore().getListState(
+			new ListStateDescriptor<>(
+				"partition-monitoring-state",
+				LongSerializer.INSTANCE
+			)
+		);
+		this.distinctPartsState = context.getOperatorStateStore().getListState(
+			new ListStateDescriptor<>(
+				"partition-monitoring-state",
+				new ListSerializer<>(new ListSerializer<>(StringSerializer.INSTANCE))
+			)
+		);
+
+		this.client = this.hiveShim.getHiveMetastoreClient(new HiveConf(conf.conf(), HiveConf.class));
+
+		Table hiveTable = client.getTable(tablePath.getDatabaseName(), tablePath.getObjectName());
+		this.tableProps = HiveReflectionUtils.getTableMetadata(hiveShim, hiveTable);
+		this.defaultPartitionName = conf.conf().get(HiveConf.ConfVars.DEFAULTPARTITIONNAME.varname,
+				HiveConf.ConfVars.DEFAULTPARTITIONNAME.defaultStrVal);
+
+		this.distinctPartitions = new HashSet<>();
+		if (context.isRestored()) {
+			LOG.info("Restoring state for the {}.", getClass().getSimpleName());
+			this.currentReadTime = this.currReadTimeState.get().iterator().next();
+			this.distinctPartitions.addAll(this.distinctPartsState.get().iterator().next());
+		} else {
+			LOG.info("No state to restore for the {}.", getClass().getSimpleName());
+			this.currentReadTime = this.startupTimestampMillis;
+		}
+	}
+
+	@Override
+	public void run(SourceContext<TimestampedHiveInputSplit> context) throws Exception {
+		checkpointLock = context.getCheckpointLock();
+		while (isRunning) {
+			synchronized (checkpointLock) {
+				monitorAndForwardSplits(context);
+			}
+			Thread.sleep(interval);
+		}
+	}
+
+	private void monitorAndForwardSplits(
+			SourceContext<TimestampedHiveInputSplit> context) throws IOException, TException {
+		assert (Thread.holdsLock(checkpointLock));
+
+		List<Partition> partitions = client.listPartitionsByFilter(
+				tablePath.getDatabaseName(),
+				tablePath.getObjectName(),
+				strategy.generateFetchFilter(partitionKeys, currentReadTime),
+				(short) -1);
+
+		if (partitions.isEmpty()) {
+			return;
+		}
+
+		long maxTime = Long.MIN_VALUE;
+		for (Partition partition : partitions) {
+			List<String> partSpec = partition.getValues();
+			if (!this.distinctPartitions.contains(partSpec)) {
+				this.distinctPartitions.add(partition.getValues());
+				long time = this.strategy.extractPartTime(partitionKeys, partition.getValues());
+				if (time > maxTime) {
+					maxTime = time;
+				}
+				HiveTableInputSplit[] splits = HiveTableInputFormat.createInputSplits(
+						this.readerParallelism,
+						Collections.singletonList(toHiveTablePartition(partition)),
+						this.conf.conf());
+				for (HiveTableInputSplit split : splits) {
+					context.collect(new TimestampedHiveInputSplit(time, split));
+				}
+			}
+		}
+		this.currentReadTime = maxTime;
+
+		this.distinctPartitions.removeIf(partSpec -> this.strategy.canExpireForDistinct(
+				this.strategy.extractPartTime(partitionKeys, partSpec),
+				this.currentReadTime));
+	}
+
+	private HiveTablePartition toHiveTablePartition(Partition p) {
+		return HiveTableSource.toHiveTablePartition(
+				partitionKeys, fieldNames, fieldTypes, hiveShim, tableProps, defaultPartitionName, p);
+	}
+
+	@Override
+	public void snapshotState(FunctionSnapshotContext context) throws Exception {
+		Preconditions.checkState(this.currReadTimeState != null,
+				"The " + getClass().getSimpleName() + " state has not been properly initialized.");
+
+		this.currReadTimeState.clear();
+		this.currReadTimeState.add(this.currentReadTime);
+
+		this.distinctPartsState.clear();
+		this.distinctPartsState.add(new ArrayList<>(this.distinctPartitions));
+
+		if (LOG.isDebugEnabled()) {
+			LOG.debug("{} checkpointed {}.", getClass().getSimpleName(), currentReadTime);
+		}
+	}
+
+	@Override
+	public void close() throws Exception {
+		super.close();
+
+		if (checkpointLock != null) {
+			synchronized (checkpointLock) {
+				currentReadTime = Long.MAX_VALUE;
+				isRunning = false;
+			}
+		}
+	}
+
+	@Override
+	public void cancel() {
+		if (checkpointLock != null) {
+			// this is to cover the case where cancel() is called before the run()

Review comment:
       this is from another thread.




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