Github user gatorsmile commented on a diff in the pull request: https://github.com/apache/spark/pull/15024#discussion_r79328309 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSource.scala --- @@ -507,3 +400,117 @@ case class DataSource( } } } + +object DataSource { + /** A map to maintain backward compatibility in case we move data sources around. */ + private val backwardCompatibilityMap: Map[String, String] = { + val jdbc = classOf[JdbcRelationProvider].getCanonicalName + val json = classOf[JsonFileFormat].getCanonicalName + val parquet = classOf[ParquetFileFormat].getCanonicalName + val csv = classOf[CSVFileFormat].getCanonicalName + val libsvm = "org.apache.spark.ml.source.libsvm.LibSVMFileFormat" + val orc = "org.apache.spark.sql.hive.orc.OrcFileFormat" + + Map( + "org.apache.spark.sql.jdbc" -> jdbc, + "org.apache.spark.sql.jdbc.DefaultSource" -> jdbc, + "org.apache.spark.sql.execution.datasources.jdbc.DefaultSource" -> jdbc, + "org.apache.spark.sql.execution.datasources.jdbc" -> jdbc, + "org.apache.spark.sql.json" -> json, + "org.apache.spark.sql.json.DefaultSource" -> json, + "org.apache.spark.sql.execution.datasources.json" -> json, + "org.apache.spark.sql.execution.datasources.json.DefaultSource" -> json, + "org.apache.spark.sql.parquet" -> parquet, + "org.apache.spark.sql.parquet.DefaultSource" -> parquet, + "org.apache.spark.sql.execution.datasources.parquet" -> parquet, + "org.apache.spark.sql.execution.datasources.parquet.DefaultSource" -> parquet, + "org.apache.spark.sql.hive.orc.DefaultSource" -> orc, + "org.apache.spark.sql.hive.orc" -> orc, + "org.apache.spark.ml.source.libsvm.DefaultSource" -> libsvm, + "org.apache.spark.ml.source.libsvm" -> libsvm, + "com.databricks.spark.csv" -> csv + ) + } + + /** + * Class that were removed in Spark 2.0. Used to detect incompatibility libraries for Spark 2.0. + */ + private val spark2RemovedClasses = Set( + "org.apache.spark.sql.DataFrame", + "org.apache.spark.sql.sources.HadoopFsRelationProvider", + "org.apache.spark.Logging") + + /** Given a provider name, look up the data source class definition. */ + def lookupDataSource(provider0: String): Class[_] = { + val provider = backwardCompatibilityMap.getOrElse(provider0, provider0) + val provider2 = s"$provider.DefaultSource" + val loader = Utils.getContextOrSparkClassLoader + val serviceLoader = ServiceLoader.load(classOf[DataSourceRegister], loader) + + try { + serviceLoader.asScala.filter(_.shortName().equalsIgnoreCase(provider)).toList match { + // the provider format did not match any given registered aliases + case Nil => + try { + Try(loader.loadClass(provider)).orElse(Try(loader.loadClass(provider2))) match { + case Success(dataSource) => + // Found the data source using fully qualified path + dataSource + case Failure(error) => + if (provider.toLowerCase == "orc" || + provider.startsWith("org.apache.spark.sql.hive.orc")) { + throw new AnalysisException( + "The ORC data source must be used with Hive support enabled") + } else if (provider.toLowerCase == "avro" || + provider == "com.databricks.spark.avro") { + throw new AnalysisException( + s"Failed to find data source: ${provider.toLowerCase}. Please find an Avro " + + "package at " + + "https://cwiki.apache.org/confluence/display/SPARK/Third+Party+Projects") + } else { + throw new ClassNotFoundException( + s"Failed to find data source: $provider. Please find packages at " + + "https://cwiki.apache.org/confluence/display/SPARK/Third+Party+Projects", + error) + } + } + } catch { + case e: NoClassDefFoundError => // This one won't be caught by Scala NonFatal + // NoClassDefFoundError's class name uses "/" rather than "." for packages + val className = e.getMessage.replaceAll("/", ".") + if (spark2RemovedClasses.contains(className)) { + throw new ClassNotFoundException(s"$className was removed in Spark 2.0. " + + "Please check if your library is compatible with Spark 2.0", e) + } else { + throw e + } + } + case head :: Nil => + // there is exactly one registered alias + head.getClass + case sources => + // There are multiple registered aliases for the input + sys.error(s"Multiple sources found for $provider " + + s"(${sources.map(_.getClass.getName).mkString(", ")}), " + + "please specify the fully qualified class name.") + } + } catch { + case e: ServiceConfigurationError if e.getCause.isInstanceOf[NoClassDefFoundError] => + // NoClassDefFoundError's class name uses "/" rather than "." for packages + val className = e.getCause.getMessage.replaceAll("/", ".") + if (spark2RemovedClasses.contains(className)) { + throw new ClassNotFoundException(s"Detected an incompatible DataSourceRegister. " + + "Please remove the incompatible library from classpath or upgrade it. " + + s"Error: ${e.getMessage}", e) + } else { + throw e + } + } + } --- End diff -- To the other reviewers, the above source codes are completely identical to the previous `lookupDataSource`, `backwardCompatibilityMap` and `spark2RemovedClasses`
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