=lib Make use of CompletionStage#handle instead of CompletionStage#wh…

…enComplete for better performance.

project/MimaFilters.scala

@@ -31,6 +31,10 @@ object MimaFilters extends AutoPlugin {
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.Predef#ArrayCharSequence.isEmpty"),
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.ArrayCharSequence.isEmpty"),
 
+    // KEEP: make use of CompletionStage#handle to get a better performance than CompletionStage#whenComplete.
+    ProblemFilters.exclude[MissingTypesProblem]("scala.concurrent.impl.FutureConvertersImpl$P"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.concurrent.impl.FutureConvertersImpl#P.andThen"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.concurrent.impl.FutureConvertersImpl#P.apply"),
   )
 
   override val buildSettings = Seq(

src/library/scala/concurrent/impl/FutureConvertersImpl.scala

@@ -91,11 +91,17 @@ private[scala] object FutureConvertersImpl {
     override def toString(): String = super[CompletableFuture].toString
   }
 
-  final class P[T](val wrapped: CompletionStage[T]) extends DefaultPromise[T] with BiConsumer[T, Throwable] {
+  final class P[T](val wrapped: CompletionStage[T]) extends DefaultPromise[T] with BiConsumer[T, Throwable]
+    with BiFunction[T, Throwable, Unit] {
     override def accept(v: T, e: Throwable): Unit = {
       if (e == null) success(v)
       else failure(e)
     }
+
+    override def apply(v: T, e: Throwable): Unit = {
+      if (e == null) success(v)
+      else failure(e)
+    }
   }
 }
 

src/library/scala/jdk/javaapi/FutureConverters.scala

@@ -72,7 +72,7 @@ object FutureConverters {
       case f: Future[T @unchecked] => f
       case _ =>
         val p = new P[T](cs)
-        cs whenComplete p
+        cs.handle(p)
         p.future
     }
   }