measure/src/main/scala/org/apache/griffin/measure/step/write/MetricWriteStep.scala

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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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  http://www.apache.org/licenses/LICENSE-2.0

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specific language governing permissions and limitations
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*/
package org.apache.griffin.measure.step.write

import org.apache.griffin.measure.configuration.enums._
import org.apache.griffin.measure.context.DQContext
import org.apache.griffin.measure.step.builder.ConstantColumns
import org.apache.griffin.measure.utils.JsonUtil
import org.apache.griffin.measure.utils.ParamUtil._

/**
  * write metrics into context metric wrapper
  */
case class MetricWriteStep(name: String,
                           inputName: String,
                           flattenType: FlattenType,
                           writeTimestampOpt: Option[Long] = None
                          ) extends WriteStep {

  val emptyMetricMap = Map[Long, Map[String, Any]]()
  val emptyMap = Map[String, Any]()

  def execute(context: DQContext): Boolean = {
    val timestamp = writeTimestampOpt.getOrElse(context.contextId.timestamp)

    // get metric list from data frame
    val metricMaps: Seq[Map[String, Any]] = getMetricMaps(context)

    // get timestamp and normalize metric
    val writeMode = writeTimestampOpt.map(_ => SimpleMode).getOrElse(context.writeMode)
    val timestampMetricMap: Map[Long, Map[String, Any]] = writeMode match {

      case SimpleMode =>
        val metrics: Map[String, Any] = flattenMetric(metricMaps, name, flattenType)
        emptyMetricMap + (timestamp -> metrics)

      case TimestampMode =>
        val tmstMetrics = metricMaps.map { metric =>
          val tmst = metric.getLong(ConstantColumns.tmst, timestamp)
          val pureMetric = metric.removeKeys(ConstantColumns.columns)
          (tmst, pureMetric)
        }
        tmstMetrics.groupBy(_._1).map { pair =>
          val (k, v) = pair
          val maps = v.map(_._2)
          val mtc = flattenMetric(maps, name, flattenType)
          (k, mtc)
        }
    }

    // write to metric wrapper
    timestampMetricMap.foreach { pair =>
      val (timestamp, v) = pair
      context.metricWrapper.insertMetric(timestamp, v)
    }

    true
  }

  private def getMetricMaps(context: DQContext): Seq[Map[String, Any]] = {
    try {
      val pdf = context.sqlContext.table(s"`${inputName}`")
      val records = pdf.toJSON.collect()
      if (records.size > 0) {
        records.flatMap { rec =>
          try {
            val value = JsonUtil.toAnyMap(rec)
            Some(value)
          } catch {
            case e: Throwable => None
          }
        }.toSeq
      } else Nil
    } catch {
      case e: Throwable =>
        error(s"get metric ${name} fails", e)
        Nil
    }
  }

  private def flattenMetric(metrics: Seq[Map[String, Any]], name: String, flattenType: FlattenType
                             ): Map[String, Any] = {
    flattenType match {
      case EntriesFlattenType => metrics.headOption.getOrElse(emptyMap)
      case ArrayFlattenType => Map[String, Any]((name -> metrics))
      case MapFlattenType =>
        val v = metrics.headOption.getOrElse(emptyMap)
        Map[String, Any]((name -> v))
      case _ =>
        if (metrics.size > 1) Map[String, Any]((name -> metrics))
        else metrics.headOption.getOrElse(emptyMap)
    }
  }

}