1 files changed, 70 insertions, 0 deletions
diff --git a/test/scalacheck/concurrent-map.scala b/test/scalacheck/concurrent-map.scala
new file mode 100644
index 0000000000..0dae7a98bd
--- /dev/null
+++ b/test/scalacheck/concurrent-map.scala
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+import java.util.concurrent._
+import scala.collection._
+import scala.collection.JavaConverters._
+import org.scalacheck._
+import org.scalacheck.Prop._
+import org.scalacheck.Gen._
+
+object ConcurrentMapTest extends Properties("concurrent.TrieMap") {
+
+  case class Wrap(i: Int) {
+    override def hashCode = i * 0x9e3775cd
+  }
+
+  /* generators */
+
+  val sizes = choose(0, 20000)
+
+  val threadCounts = choose(2, 16)
+
+  val threadCountsAndSizes = for {
+    p <- threadCounts
+    sz <- sizes
+  } yield (p, sz);
+
+
+  /* helpers */
+
+  def inParallel[T](totalThreads: Int)(body: Int => T): Seq[T] = {
+    val threads = for (idx <- 0 until totalThreads) yield new Thread {
+      setName("ParThread-" + idx)
+      private var res: T = _
+      override def run() {
+        res = body(idx)
+      }
+      def result = {
+        this.join()
+        res
+      }
+    }
+
+    threads foreach (_.start())
+    threads map (_.result)
+  }
+
+  property("concurrent getOrElseUpdate insertions") = forAll(threadCounts, sizes) {
+    (p, sz) =>
+    val chm = new ConcurrentHashMap[Wrap, Int]().asScala
+
+    val results = inParallel(p) {
+      idx =>
+      for (i <- 0 until sz) yield chm.getOrElseUpdate(new Wrap(i), idx)
+    }
+
+    val resultSets = for (i <- 0 until sz) yield results.map(_(i)).toSet
+    val largerThanOne = resultSets.zipWithIndex.find(_._1.size != 1)
+    val allThreadsAgreeOnWhoInserted = {
+      largerThanOne == None
+    } :| s"$p threads agree on who inserted [disagreement (differentResults, position) = $largerThanOne]"
+
+    allThreadsAgreeOnWhoInserted
+  }
+
+
+}
+
+
+
+
+
+