class SimpleWritableDataSource extends DataSourceV2 with ReadSupport with WriteSupport {
override def createReader（）
override def createWriter()
}
构造 DataSourceReader
class Reader(path: String, conf: Configuration) extends DataSourceReader
{
/**
* Returns the actual schema of this data source reader, which may be different from the physical
* schema of the underlying storage, as column pruning or other optimizations may happen.
*
override def readSchema()
/**
* Returns a list of reader factories. Each factory is responsible for creating a data reader to
* output data for one RDD partition. That means the number of factories returned here is same as
* the number of RDD partitions this scan outputs.
override def createDataReaderFactories()
}
构造 DataReaderFactory 、DataReader
class SimpleCSVDataReaderFactory(path: String, conf: SerializableConfiguration)
extends DataReaderFactory[Row] with DataReader[Row]
{
/**
* Returns a data reader to do the actual reading work.
*
override def createDataReader(): DataReader[Row]
}
构造 DataSourceWriter
class Writer(jobId: String, path: String, conf: Configuration) extends DataSourceWriter {
/**
* Creates a writer factory which will be serialized and sent to executors.
*
override def createWriterFactory(): DataWriterFactory[Row]
override def commit(messages: Array[WriterCommitMessage]): Unit
override def abort(messages: Array[WriterCommitMessage]): Unit
}
构造 DataWriterFactory
class SimpleCSVDataWriterFactory(path: String, jobId: String, conf: SerializableConfiguration)
extends DataWriterFactory[Row] {
/**
* Returns a data writer to do the actual writing work.
*
override def createDataWriter(partitionId: Int, attemptNumber: Int): DataWriter[Row] = {
}
}
构造 DataWriter
class SimpleCSVDataWriter(fs: FileSystem, file: Path) extends DataWriter[Row] {
}