SI-7938 - parallel collections should use default ExecutionContext

Parallel collections now use `scala.concurrent.ExecutionContext`
by default.

The `ExecutionContextTaskSupport` is optimized to use the
`ForkJoinPool` underlying the `ExecutionContext` if possible.
Otherwise, a fallback `TaskSupport` that creates a reduction tree and
execute an operation through `Future`s is used.

1 files changed, 7 insertions, 4 deletions

diff --git a/test/files/scalacheck/parallel-collections/ParallelHashSetCheck.scala b/test/files/scalacheck/parallel-collections/ParallelHashSetCheck.scala
index 8b41908a26..91de2472a7 100644
--- a/test/files/scalacheck/parallel-collections/ParallelHashSetCheck.scala
+++ b/test/files/scalacheck/parallel-collections/ParallelHashSetCheck.scala
@@ -24,6 +24,8 @@ abstract class ParallelHashSetCheck[T](tp: String) extends ParallelSetCheck[T]("
 
   def hasStrictOrder = false
 
+  def tasksupport: TaskSupport
+
   def ofSize(vals: Seq[Gen[T]], sz: Int) = {
     val hm = new mutable.HashSet[T]
     val gen = vals(rnd.nextInt(vals.size))
@@ -32,19 +34,20 @@ abstract class ParallelHashSetCheck[T](tp: String) extends ParallelSetCheck[T]("
   }
 
   def fromTraversable(t: Traversable[T]) = {
-    val phm = new ParHashSet[T]
+    val phs = new ParHashSet[T]
+    phs.tasksupport = tasksupport
     var i = 0
     for (kv <- t.toList) {
-      phm += kv
+      phs += kv
       i += 1
     }
-    phm
+    phs
   }
 
 }
 
 
-object IntParallelHashSetCheck extends ParallelHashSetCheck[Int]("Int")
+class IntParallelHashSetCheck(val tasksupport: TaskSupport) extends ParallelHashSetCheck[Int]("Int")
 with IntOperators
 with IntValues
 {