Add toTSV method

[chuwy]

In order to convert Event back to TSV.

We can write a property-based test with Event -> TSV -> Event check.

[benjben]

Benchmark in Enrich:

package com.snowplowanalytics.snowplow.enrich.bench

import org.openjdk.jmh.annotations._

import java.util.concurrent.TimeUnit
import com.snowplowanalytics.snowplow.enrich.common.outputs.EnrichedEvent

/**
 * @example
 * {{{
 *   jmh:run -i 15 -wi 10 -f1 -t1 EnrichBench
 * }}}
 */
@State(Scope.Thread)
@BenchmarkMode(Array(Mode.AverageTime))
@OutputTimeUnit(TimeUnit.MICROSECONDS)
class ToTSVBench {

  @Benchmark
  def toTSV(state: ToTSVBench.BenchState) = {
    ToTSVBench.tabSeparatedEnrichedEvent(state.enriched)
  }
}

object ToTSVBench {
  @State(Scope.Benchmark)
  class BenchState {
    var enriched: EnrichedEvent = _

    @Setup(Level.Trial)
    def setup(): Unit = {
      enriched = new EnrichedEvent()
    }
  }

  def tabSeparatedEnrichedEvent(enrichedEvent: EnrichedEvent): String =
    enrichedEvent.getClass.getDeclaredFields
      .map { field =>
        field.setAccessible(true)
        Option(field.get(enrichedEvent)).getOrElse("")
      }
      .mkString("\t")
}

Results with -i 10 -wi 3 -f2 -t2:

[info] Result "com.snowplowanalytics.snowplow.enrich.bench.ToTSVBench.toTSV":
[info]   8.322 ±(99.9%) 0.372 us/op [Average]
[info]   (min, avg, max) = (7.610, 8.322, 9.323), stdev = 0.429
[info]   CI (99.9%): [7.950, 8.695] (assumes normal distribution)

[chuwy]

I encourage you to implement tabSeparatedEnrichedEvent as:

  private val EnrichedFields =
    classOf[EnrichedEvent].getDeclaredFields
      .filterNot(_.getName.equals("pii"))
      .map { field => field.setAccessible(true); field }
      .toList

  def tabSeparatedEnrichedEvent(enrichedEvent: EnrichedEvent): String =
    EnrichedFields
      .map { field =>
        val prop = field.get(enrichedEvent)
        if (prop == null) "" else prop.toString
      }
      .mkString("\t")

It is how it implemented in FS2 Enrich.

[chuwy]

Also worth adding some fields to the event to make it actually doing something - ideally into beginning, middle and end of an object as JVM might make some experiment-breaking hotpath optimizations.

[benjben]

With this implementation :

@State(Scope.Thread)
@BenchmarkMode(Array(Mode.AverageTime))
@OutputTimeUnit(TimeUnit.MICROSECONDS)
class ToTSVBench {

  @Benchmark
  def toTSV(state: ToTSVBench.BenchState) = {
    ToTSVBench.tabSeparatedEnrichedEvent(state.enriched)
  }
}

object ToTSVBench {
  @State(Scope.Benchmark)
  class BenchState {
    var enriched: EnrichedEvent = _

    @Setup(Level.Trial)
    def setup(): Unit = {
      enriched = new EnrichedEvent()
      enriched.app_id = "app_id"
      enriched.geo_country = "FR"
      enriched.geo_country = "FR"
      enriched.mkt_campaign = "campaign"
      enriched.os_name = "Android"
      enriched.event_vendor = "vendor"
    }
  }

  private val EnrichedFields =
    classOf[EnrichedEvent].getDeclaredFields
      .filterNot(_.getName.equals("pii"))
      .map { field => field.setAccessible(true); field }
      .toList

  def tabSeparatedEnrichedEvent(enrichedEvent: EnrichedEvent): String =
    EnrichedFields
      .map { field =>
        val prop = field.get(enrichedEvent)
        if (prop == null) "" else prop.toString
      }
      .mkString("\t")
}

Results for +jmh:run -i 10 -wi 3 -f2 -t2 .*ToTSVBench.* :

[info] Result "com.snowplowanalytics.snowplow.enrich.bench.ToTSVBench.toTSV":
[info]   8.267 ±(99.9%) 0.830 us/op [Average]
[info]   (min, avg, max) = (5.829, 8.267, 9.701), stdev = 0.956
[info]   CI (99.9%): [7.437, 9.098] (assumes normal distribution)

[benjben]

Results with the manual implementation with List(...).mkString :

[info] Result "com.snowplowanalytics.snowplow.analytics.scalasdk.benchmark.ToTsvBenchmark.toTsv":
[info]   4.389 ±(99.9%) 0.085 us/op [Average]
[info]   (min, avg, max) = (4.264, 4.389, 4.610), stdev = 0.098
[info]   CI (99.9%): [4.304, 4.474] (assumes normal distribution)

Only 2x improvement

[benjben]

Results with the manual implementation with ... + '\t' + ... + '\t' + ... :

[info] Result "com.snowplowanalytics.snowplow.analytics.scalasdk.benchmark.ToTsvBenchmark.toTsv":
[info]   3.982 ±(99.9%) 0.381 us/op [Average]
[info]   (min, avg, max) = (3.486, 3.982, 5.379), stdev = 0.439
[info]   CI (99.9%): [3.600, 4.363] (assumes normal distribution)

A little bit better