Unique index failed when vertex creation running in parallel

[xdev-developer]

Hi all.
Unique index not working when run vertex creation in parallel.
Titan version 1.0.0

How to reproduce.

import java.io.File

import com.thinkaurelius.titan.core.{TitanFactory, TitanGraph}
import org.apache.commons.configuration.BaseConfiguration
import org.apache.commons.io.{FileUtils, IOUtils}
import org.apache.tinkerpop.gremlin.structure.{Graph, Vertex}

import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.{Await, Future}
import scala.util.Random

object Launcher {

  val DB_DIR = "/tmp/titan-index-test"

  def openGraph(): Graph = {
    val conf = new BaseConfiguration()
    conf.setProperty("schema.default", "none")
    conf.setProperty("storage.backend", "berkeleyje")
    conf.setProperty("storage.directory", "/tmp/titan-index-test")
    createSchema(TitanFactory.open(conf))
  }

  def createSchema(graph: TitanGraph): TitanGraph = {
    val mgmt = graph.openManagement()
    val label = mgmt.makeVertexLabel("user").make()
    val key = mgmt.makePropertyKey("username").dataType(classOf[String]).make()
    val pass = mgmt.makePropertyKey("pass").dataType(classOf[String]).make()

    mgmt.buildIndex("usernameUnique", classOf[Vertex]).addKey(key).indexOnly(label).unique().buildCompositeIndex()

    mgmt.commit()
    graph
  }

  def main(args: Array[String]): Unit = {
    System.out.println("Start application")
    FileUtils.deleteQuietly(new File(DB_DIR))

    val graph = openGraph()

    (1 to 10).foreach { i =>
      println("test: " + i)

      val fSeq = Future.sequence(test(graph))

      println("Awaiting")
      Await.result(fSeq, 1.minute)

      val count = graph.traversal().V().has("username", "Den").count().next()
      println("Count of vertices: " + count)
      assert(count == 1, "Users > 1")
    }

    println("Closing application")
    graph.close()
    System.exit(0)
  }

  def test(graph: Graph): List[Future[Boolean]] = {
    (1 to 10).toList.map { _ =>
      Future {
        try {
          println("Add vertex!!!")
          val v = graph.addVertex("user")
          v.property("pass", "test")
          v.property("username", "Den")
          graph.tx().commit()
          true
        } catch {
          case ex: Exception =>
            println(ex.getMessage)
            false
        }
      }
    }
  }
}

Result:

Adding this property for key [username] and value [Den] violates a uniqueness constraint [usernameUnique]
Adding this property for key [username] and value [Den] violates a uniqueness constraint [usernameUnique]
Adding this property for key [username] and value [Den] violates a uniqueness constraint [usernameUnique]
Adding this property for key [username] and value [Den] violates a uniqueness constraint [usernameUnique]
Count of vertices: 2
Exception in thread "main" java.lang.AssertionError: assertion failed: Users > 1
	at scala.Predef$.assert(Predef.scala:170)
	at com.xdev.titan.Launcher$$anonfun$main$1.apply$mcVI$sp(Launcher.scala:55)
	at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:160)
	at com.xdev.titan.Launcher$.main(Launcher.scala:45)
	at com.xdev.titan.Launcher.main(Launcher.scala)

This additional vertex cannot be removed, operation failed with status NOT_FOUND.