[GitHub] [iceberg] Simon0806 commented on a change in pull request #1145: Implement the flink stream writer to accept the row data and emit the complete data files event to downstream

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

Simon0806 commented on a change in pull request #1145:
URL: https://github.com/apache/iceberg/pull/1145#discussion_r449877267



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File path: flink/src/main/java/org/apache/iceberg/flink/IcebergStreamWriter.java
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@@ -0,0 +1,225 @@
+/*
+ * 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;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import org.apache.flink.api.common.ExecutionConfig;
+import org.apache.flink.api.java.ClosureCleaner;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.functions.sink.SinkFunction;
+import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
+import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+import org.apache.flink.table.api.TableSchema;
+import org.apache.flink.types.Row;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.MetricsConfig;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.Table;
+import org.apache.iceberg.exceptions.RuntimeIOException;
+import org.apache.iceberg.flink.data.FlinkParquetWriters;
+import org.apache.iceberg.flink.writer.FileAppenderFactory;
+import org.apache.iceberg.flink.writer.OutputFileFactory;
+import org.apache.iceberg.flink.writer.TaskWriter;
+import org.apache.iceberg.flink.writer.TaskWriterFactory;
+import org.apache.iceberg.hadoop.SerializableConfiguration;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.OutputFile;
+import org.apache.iceberg.parquet.Parquet;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.types.TypeUtil;
+import org.apache.iceberg.util.PropertyUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.apache.iceberg.TableProperties.DEFAULT_FILE_FORMAT;
+import static org.apache.iceberg.TableProperties.DEFAULT_FILE_FORMAT_DEFAULT;
+import static org.apache.iceberg.TableProperties.WRITE_TARGET_FILE_SIZE_BYTES;
+import static org.apache.iceberg.TableProperties.WRITE_TARGET_FILE_SIZE_BYTES_DEFAULT;
+
+class IcebergStreamWriter extends AbstractStreamOperator<SerializableDataFile>
+    implements OneInputStreamOperator<Row, SerializableDataFile> {
+
+  private static final long serialVersionUID = 1L;
+  private static final Logger LOG = LoggerFactory.getLogger(IcebergStreamWriter.class);
+
+  private final String tablePath;
+  private final SerializableConfiguration conf;
+  private Schema readSchema;
+
+  private transient Table table;
+  private transient TaskWriter<Row> writer;
+  private transient int subTaskId;
+
+  /**
+   * Be careful to do the initialization in this constructor, because in {@link DataStream#addSink(SinkFunction)}
+   * it will call {@link ClosureCleaner#clean(Object, ExecutionConfig.ClosureCleanerLevel, boolean)} to set all the
+   * non-serializable members to be null.
+   *
+   * @param tablePath  The base path of the iceberg table.
+   * @param readSchema The schema of source data.
+   * @param conf       The hadoop's configuration.
+   */
+  private IcebergStreamWriter(String tablePath, Schema readSchema, Configuration conf) {
+    this.tablePath = tablePath;
+    this.conf = new SerializableConfiguration(conf);
+    this.readSchema = readSchema;
+  }
+
+  @Override
+  public void open() {
+    this.table = TableUtil.findTable(tablePath, conf.get());
+    if (this.readSchema != null) {
+      // reassign ids to match the existing table schema
+      readSchema = TypeUtil.reassignIds(readSchema, table.schema());
+      TypeUtil.validateWriteSchema(readSchema, table.schema(), true, true);
+    }
+
+    this.subTaskId = getRuntimeContext().getIndexOfThisSubtask();
+
+    // Initialize the task writer.
+    FileFormat fileFormat = getFileFormat();
+    FileAppenderFactory<Row> appenderFactory = new FlinkFileAppenderFactory(table);
+    OutputFileFactory outputFileFactory = new OutputFileFactory(table, fileFormat, subTaskId);
+    this.writer = TaskWriterFactory.createTaskWriter(table.spec(),
+        appenderFactory,
+        outputFileFactory,
+        getTargetFileSizeBytes(),
+        fileFormat);
+  }
+
+  @Override
+  public void prepareSnapshotPreBarrier(long checkpointId) throws Exception {
+    LOG.info("Iceberg writer {} subtask {} begin preparing for checkpoint {}", tablePath, subTaskId, checkpointId);
+    // close all open files and emit files to downstream committer operator
+    writer.close();
+    for (DataFile dataFile : writer.getCompleteFiles()) {
+      emit(dataFile);
+    }
+    // Remember to clear the writer's cached complete files.
+    writer.reset();
+    LOG.info("Iceberg writer {} subtask {} completed preparing for checkpoint {}", tablePath, subTaskId, checkpointId);
+  }
+
+  @Override
+  public void processElement(StreamRecord<Row> element) throws Exception {
+    Row value = element.getValue();
+    writer.append(value);
+
+    // Emit the data file entries to downstream committer operator if there exist any complete files.
+    List<DataFile> completeFiles = writer.getCompleteFiles();
+    if (!completeFiles.isEmpty()) {
+      completeFiles.forEach(this::emit);
+      // Remember to clear the writer's cached complete files.
+      writer.reset();
+    }
+  }
+
+  @Override
+  public void close() throws Exception {
+    if (writer != null) {
+      writer.close();

Review comment:
       Hi Jingsong, Actually if a collector.collect happens in close, what's the next behaviors ? will it be processed by processElement in next operator and then called close then ? 




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