Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3406#discussion_r104158740
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/catalog/CatalogTableHelper.scala
---
@@ -0,0 +1,139 @@
+/*
+ * 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.io.IOException
+import java.lang.reflect.Modifier
+import java.net.URL
+import java.util.Properties
+
+import org.apache.flink.table.annotation.ExternalCatalogCompatible
+import
org.apache.flink.table.api.{ExternalCatalogTableTypeAlreadyExistException,
ExternalCatalogTableTypeNotExistException}
+import org.apache.flink.table.plan.schema.TableSourceTable
+import org.apache.flink.table.plan.stats.FlinkStatistic
+import org.apache.flink.table.sources.TableSource
+import org.apache.flink.util.InstantiationUtil
+import org.reflections.Reflections
+import org.slf4j.{Logger, LoggerFactory}
+
+import scala.collection.JavaConverters._
+import scala.collection.mutable.HashMap
+
+/**
+ * The utility class is used to convert ExternalCatalogTable to
TableSourceTable.
+ */
+object CatalogTableHelper {
+
+ // config file to specifier the scan package to search tableSources
+ // which is compatible with external catalog.
+ private val tableSourceConfigFileName = "externalcatalogTable.properties"
+
+ private val LOG: Logger = LoggerFactory.getLogger(this.getClass)
+
+ // registered tableSources which are compatible with external catalog.
+ // Key is table type name, Value is converter class.
+ private val tableSourceTypeToConvertersClazz = {
+ val registeredConverters =
+ new HashMap[String, Class[_ <: TableSourceConverter[_]]]
+ // scan all config file to find all tableSources which are compatible
with external catalog.
+ val resourceUrls =
getClass.getClassLoader.getResources(tableSourceConfigFileName)
+ while (resourceUrls.hasMoreElements) {
+ val url = resourceUrls.nextElement()
+ parseScanPackageFromConfigFile(url) match {
+ case Some(scanPackage) =>
+ val clazzWithAnnotations = new Reflections(scanPackage)
+ .getTypesAnnotatedWith(classOf[ExternalCatalogCompatible])
+ clazzWithAnnotations.asScala.foreach(clazz =>
+ if (classOf[TableSource[_]].isAssignableFrom(clazz)) {
+ if (Modifier.isAbstract(clazz.getModifiers()) ||
+ Modifier.isInterface(clazz.getModifiers)) {
+ LOG.warn(
+ s"class :[${clazz.getName}] is also with
ExternalCatalogCompatible annotation, " +
+ s"but it's an abstract clazz or an interface.")
+ } else {
+ val externalCatalogCompatible: ExternalCatalogCompatible =
+ clazz.getAnnotation(classOf[ExternalCatalogCompatible])
+ val tableSourceName = externalCatalogCompatible.tableType()
+ if (registeredConverters.contains(tableSourceName)) {
+ LOG.error(s"The table type [$tableSourceName] is already
registered.")
+ throw new
ExternalCatalogTableTypeAlreadyExistException(tableSourceName)
+ }
+ registeredConverters.put(tableSourceName,
externalCatalogCompatible.converter())
+ }
+ } else {
+ LOG.warn(
+ s"class :[${clazz.getName}] is also with
ExternalCatalogCompatible annotation, " +
+ s"but it's not sub-class of tableSource.")
+ }
+ )
+ case None =>
+ }
+ }
+ registeredConverters
+ }
+
+ /**
+ * 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(externalCatalogTable:
ExternalCatalogTable): TableSourceTable[_] = {
+ val tableType = externalCatalogTable.tableType
+ tableSourceTypeToConvertersClazz.get(tableType) match {
+ case Some(converterClazz) =>
+ val converter = InstantiationUtil.instantiate(converterClazz)
+ val convertedTableSource: TableSource[_] =
+ converter.fromExternalCatalogTable(externalCatalogTable) match {
+ case ts: TableSource[_] => ts
+ case _ => throw new RuntimeException(
+ s"the converted result from converter
${converterClazz.getName} " +
+ s"is not tableSource instance")
+ }
+
+ val flinkStatistic = externalCatalogTable.stats match {
+ case Some(stats) => FlinkStatistic.of(stats)
+ case None => FlinkStatistic.UNKNOWN
+ }
+ new TableSourceTable(convertedTableSource, flinkStatistic)
+ case None =>
+ LOG.error(s"the table type [$tableType] does not exist.")
--- End diff --
`s"Cannot find TableSource to scan table of type [$tableType]. Register
TableSources via externalCatalogTable.properties file."`
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