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, 10 insertions, 4 deletions

diff --git a/test/files/scalacheck/parallel-collections/ParallelVectorCheck.scala b/test/files/scalacheck/parallel-collections/ParallelVectorCheck.scala
index a2b6cef96d..bbebd51919 100644
--- a/test/files/scalacheck/parallel-collections/ParallelVectorCheck.scala
+++ b/test/files/scalacheck/parallel-collections/ParallelVectorCheck.scala
@@ -17,6 +17,8 @@ import scala.collection.parallel.ops._
 import immutable.Vector
 import immutable.VectorBuilder
 
+import scala.collection.parallel.TaskSupport
+
 
 
 
@@ -30,6 +32,8 @@ abstract class ParallelVectorCheck[T](tp: String) extends collection.parallel.Pa
 
   def hasStrictOrder = true
 
+  def tasksupport: TaskSupport
+
   def ofSize(vals: Seq[Gen[T]], sz: Int) = {
     val vb = new immutable.VectorBuilder[T]()
     val gen = vals(rnd.nextInt(vals.size))
@@ -38,16 +42,18 @@ abstract class ParallelVectorCheck[T](tp: String) extends collection.parallel.Pa
   }
 
   def fromSeq(a: Seq[T]) = {
-    val pa = ParVector.newCombiner[T]
-    for (elem <- a.toList) pa += elem
-    pa.result
+    val pc = ParVector.newCombiner[T]
+    for (elem <- a.toList) pc += elem
+    val pv = pc.result
+    pv.tasksupport = tasksupport
+    pv
   }
 
 }
 
 
 
-object IntParallelVectorCheck extends ParallelVectorCheck[Int]("Int") with IntSeqOperators with IntValues {
+class IntParallelVectorCheck(val tasksupport: TaskSupport) extends ParallelVectorCheck[Int]("Int") with IntSeqOperators with IntValues {
   override def instances(vals: Seq[Gen[Int]]) = oneOf(super.instances(vals), sized { sz =>
     (0 until sz).toArray.toSeq
   }, sized { sz =>