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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
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*/
package org.apache.griffin.measure.step.read

import org.apache.spark.sql._

import org.apache.griffin.measure.context.DQContext
import org.apache.griffin.measure.step.DQStep

trait ReadStep extends DQStep {

  val config: Map[String, Any]

  val cache: Boolean

  def execute(context: DQContext): Boolean = {
    info(s"read data source [${name}]")
    read(context) match {
      case Some(df) =>
//        if (needCache) context.dataFrameCache.cacheDataFrame(name, df)
        context.runTimeTableRegister.registerTable(name, df)
        true
      case _ =>
        warn(s"read data source [${name}] fails")
        false
    }
  }

  def read(context: DQContext): Option[DataFrame]

}