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From pnowojski <...@git.apache.org>
Subject [GitHub] flink pull request #6343: [FLINK-9852] [table] Expose descriptor-based sink ...
Date Tue, 17 Jul 2018 10:12:40 GMT
Github user pnowojski commented on a diff in the pull request:

    https://github.com/apache/flink/pull/6343#discussion_r202963234
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/catalog/ExternalTableUtil.scala
---
    @@ -0,0 +1,148 @@
    +/*
    + * 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.table.catalog
    +
    +import java.util
    +
    +import org.apache.flink.table.api._
    +import org.apache.flink.table.descriptors.DescriptorProperties
    +import org.apache.flink.table.factories._
    +import org.apache.flink.table.plan.schema._
    +import org.apache.flink.table.plan.stats.FlinkStatistic
    +import org.apache.flink.table.util.Logging
    +
    +
    +/**
    +  * The utility class is used to convert [[ExternalCatalogTable]] to [[TableSourceSinkTable]].
    +  *
    +  * It uses [[TableFactoryService]] for discovering.
    +  */
    +object ExternalTableUtil extends Logging {
    +
    +  /**
    +    * Converts an [[ExternalCatalogTable]] instance to a [[TableSourceTable]] instance
    +    *
    +    * @param externalCatalogTable the [[ExternalCatalogTable]] instance which to convert
    +    * @return converted [[TableSourceTable]] instance from the input catalog table
    +    */
    +  def fromExternalCatalogTable[T1, T2](
    +      tableEnv: TableEnvironment,
    +      externalCatalogTable: ExternalCatalogTable)
    +    : TableSourceSinkTable[T1, T2] = {
    +
    +    val properties = new DescriptorProperties()
    +    externalCatalogTable.addProperties(properties)
    +    val javaMap = properties.asMap
    +    val statistics = new FlinkStatistic(externalCatalogTable.getTableStats)
    +
    +    val source: Option[TableSourceTable[T1]] = tableEnv match {
    +      // check for a batch table source in this batch environment
    +      case _: BatchTableEnvironment if externalCatalogTable.isBatchTable =>
    +        createBatchTableSource(externalCatalogTable, javaMap, statistics)
    +
    +      // check for a stream table source in this stream environment
    +      case _: StreamTableEnvironment if externalCatalogTable.isStreamTable =>
    +        createStreamTableSource(externalCatalogTable, javaMap, statistics)
    +
    +      case _ =>
    +        throw new ValidationException(
    +          "External catalog table does not support the current environment for a table
source.")
    +    }
    +
    +    val sink: Option[TableSinkTable[T2]] = tableEnv match {
    +      // check for a batch table sink in this batch environment
    +      case _: BatchTableEnvironment if externalCatalogTable.isBatchTable =>
    +        createBatchTableSink(externalCatalogTable, javaMap, statistics)
    +
    +      // check for a stream table sink in this stream environment
    +      case _: StreamTableEnvironment if externalCatalogTable.isStreamTable =>
    +        createStreamTableSink(externalCatalogTable, javaMap, statistics)
    +
    +      case _ =>
    +        throw new ValidationException(
    +          "External catalog table does not support the current environment for a table
sink.")
    +    }
    +
    +    new TableSourceSinkTable[T1, T2](source, sink)
    +  }
    +
    +  private def createBatchTableSource[T](
    +      externalCatalogTable: ExternalCatalogTable,
    +      javaMap: util.Map[String, String],
    +      statistics: FlinkStatistic)
    +    : Option[TableSourceTable[T]] = if (externalCatalogTable.isTableSource) {
    --- End diff --
    
    reverse if/else branches - simpler case should be first
    
    also if you change it to
    ```
    if (!externalCatalogTable.isTableSource) {
      return None
    }
    val source = TableFactoryService
      .find(classOf[BatchTableSourceFactory[T]], javaMap)
      .createBatchTableSource(javaMap)
    val table = new BatchTableSourceTable(
      source,
      statistics)
    Some(table)
    ```
    it would even further simplify the code (reader wouldn't have to track one extra level
of nesting)
    
    ditto in other places


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