measure/src/main/scala/org/apache/griffin/measure/datasource/connector/batch/CassandraDataConnector.scala

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package org.apache.griffin.measure.datasource.connector.batch

import org.apache.spark.sql.{DataFrame, DataFrameReader, SparkSession}

import org.apache.griffin.measure.configuration.dqdefinition.DataConnectorParam
import org.apache.griffin.measure.context.TimeRange
import org.apache.griffin.measure.datasource.TimestampStorage
import org.apache.griffin.measure.utils.ParamUtil._

case class CassandraDataConnector(@transient sparkSession: SparkSession,
                                  dcParam: DataConnectorParam,
                                  timestampStorage: TimestampStorage) extends BatchDataConnector {

  val config: Map[String, Any] = dcParam.getConfig

  val Database = "database"
  val TableName = "table.name"
  val Where = "where"
  val Host = "host"
  val Port = "port"
  val User = "user"
  val Password = "password"

  val database: String = config.getString(Database, "default")
  val tableName: String = config.getString(TableName, "")
  val whereString: String = config.getString(Where, "")

  val host: String = config.getString(Host, "localhost")
  val port: Int = config.getInt(Port, 9042)
  val user: String = config.getString(User, "")
  val password: String = config.getString(Password, "")
  val wheres: Array[String] = whereString.split(",").map(_.trim).filter(_.nonEmpty)

  override def data(ms: Long): (Option[DataFrame], TimeRange) = {

    val dfOpt = try {
      sparkSession.conf.set("spark.cassandra.connection.host", host)
      sparkSession.conf.set("spark.cassandra.connection.port", port)
      sparkSession.conf.set("spark.cassandra.auth.username", user)
      sparkSession.conf.set("spark.cassandra.auth.password", password)


      val tableDef: DataFrameReader = sparkSession.read
        .format("org.apache.spark.sql.cassandra")
        .options(Map("table" -> tableName, "keyspace" -> database))

      val dataWh: String = dataWhere()

      var data: DataFrame = null
      if (wheres.length > 0) {
        data = tableDef.load().where(dataWh)
      } else {
        data = tableDef.load()
      }

      val dfOpt = Some(data)
      val preDfOpt = preProcess(dfOpt, ms)
      preDfOpt
    } catch {
      case e: Throwable =>
        error(s"load cassandra table $database.$TableName fails: ${e.getMessage}", e)
        None
    }
    val tmsts = readTmst(ms)
    (dfOpt, TimeRange(ms, tmsts))
  }

  private def dataWhere(): String = {
    if (wheres.length > 0) {
      wheres.mkString(" OR ")
    } else null
  }

}