Merge pull request #5147 from dotta/wip/application-lifecycle-api-exi…

…stentials

ApplicationLifecycle stop hook can take an existential type

framework/src/play-java/src/main/java/play/inject/DelegateApplicationLifecycle.java

@@ -20,7 +20,7 @@ public DelegateApplicationLifecycle(play.api.inject.ApplicationLifecycle delegat
     }
 
     @Override
-    public void addStopHook(final Callable<F.Promise<Void>> hook) {
+    public void addStopHook(final Callable<F.Promise<?>> hook) {
         delegate.addStopHook(hook);
     }
 }

framework/src/play-test/src/main/scala/play/api/test/Fakes.scala

@@ -225,7 +225,7 @@ case class FakeApplication(
   override def plugins: Seq[Plugin.Deprecated] = app.plugins
   override def requestHandler: HttpRequestHandler = app.requestHandler
   override def errorHandler: HttpErrorHandler = app.errorHandler
-  override def stop(): Future[Unit] = app.stop()
+  override def stop(): Future[_] = app.stop()
   override def injector: Injector = app.injector
 }
 

framework/src/play/src/main/java/play/inject/ApplicationLifecycle.java

@@ -25,5 +25,5 @@ public interface ApplicationLifecycle {
      * The stop hook should redeem the returned future when it is finished shutting down.  It is acceptable to stop
      * immediately and return a successful future.
      */
-    public void addStopHook(Callable<F.Promise<Void>> hook);
+    public void addStopHook(Callable<F.Promise<?>> hook);
 }

framework/src/play/src/main/scala/play/api/Application.scala

@@ -204,7 +204,7 @@ trait Application {
   /**
    * Stop the application.  The returned future will be redeemed when all stop hooks have been run.
    */
-  def stop(): Future[Unit]
+  def stop(): Future[_]
 
   /**
    * Get the injector for this application.

framework/src/play/src/main/scala/play/api/inject/ApplicationLifecycle.scala

@@ -54,18 +54,16 @@ trait ApplicationLifecycle {
    * The stop hook should redeem the returned future when it is finished shutting down.  It is acceptable to stop
    * immediately and return a successful future.
    */
-  def addStopHook(hook: () => Future[Unit]): Unit
+  def addStopHook(hook: () => Future[_]): Unit
 
   /**
    * Add a stop hook to be called when the application stops.
    *
    * The stop hook should redeem the returned future when it is finished shutting down.  It is acceptable to stop
    * immediately and return a successful future.
    */
-  def addStopHook(hook: Callable[F.Promise[Void]]): Unit = {
-    import play.api.libs.iteratee.Execution.Implicits.trampoline
-    addStopHook(() => hook.call().wrapped().map(_ => ()))
-  }
+  def addStopHook(hook: Callable[F.Promise[_]]): Unit =
+    addStopHook(() => hook.call().wrapped())
 }
 
 /**
@@ -74,9 +72,9 @@ trait ApplicationLifecycle {
 @Singleton
 class DefaultApplicationLifecycle extends ApplicationLifecycle {
   private val mutex = new Object()
-  @volatile private var hooks = List.empty[() => Future[Unit]]
+  @volatile private var hooks = List.empty[() => Future[_]]
 
-  def addStopHook(hook: () => Future[Unit]) = mutex.synchronized {
+  def addStopHook(hook: () => Future[_]) = mutex.synchronized {
     hooks = hook :: hooks
   }
 
@@ -85,12 +83,12 @@ class DefaultApplicationLifecycle extends ApplicationLifecycle {
    *
    * @return A future that will be redeemed once all hooks have executed.
    */
-  def stop(): Future[Unit] = {
+  def stop(): Future[_] = {
 
     // Do we care if one hook executes on another hooks redeeming thread? Hopefully not.
     import play.api.libs.iteratee.Execution.Implicits.trampoline
 
-    hooks.foldLeft(Future.successful(())) { (future, hook) =>
+    hooks.foldLeft(Future.successful[Any](())) { (future, hook) =>
       future.flatMap { _ =>
         hook().recover {
           case e => Logger.error("Error executing stop hook", e)