Add onStartup() and onShutdown() virtuals to QAbstractAspect

Gives aspects a chance to do work just prior to and just after the
main loop in QAspectManager.

Specifically the shutdown functionality is required for the upcoming
logic aspect to ensure a clean shutdown.

Added the onStartup() method for symmetry.

Change-Id: If5f32d62629543cdceb2e6e3ff6383747acb7c99
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

3 files changed, 28 insertions, 1 deletions

diff --git a/src/core/aspects/qabstractaspect.cpp b/src/core/aspects/qabstractaspect.cpp
index 1974e8af9..227457cb9 100644
--- a/src/core/aspects/qabstractaspect.cpp
+++ b/src/core/aspects/qabstractaspect.cpp
@@ -195,6 +195,14 @@ bool QAbstractAspect::isShuttingDown() const
     return d->m_aspectManager->isShuttingDown();
 }
 
+void QAbstractAspect::onStartup()
+{
+}
+
+void QAbstractAspect::onShutdown()
+{
+}
+
 } // of namespace Qt3D
 
 QT_END_NAMESPACE
diff --git a/src/core/aspects/qabstractaspect.h b/src/core/aspects/qabstractaspect.h
index 1ea814309..12d5044a1 100644
--- a/src/core/aspects/qabstractaspect.h
+++ b/src/core/aspects/qabstractaspect.h
@@ -104,6 +104,8 @@ protected:
 private:
     virtual void setRootEntity(QEntity *rootObject) = 0;
     virtual void onInitialize(const QVariantMap &data) = 0;
+    virtual void onStartup();
+    virtual void onShutdown();
     virtual void onCleanup() = 0;
 
     Q_DECLARE_PRIVATE(QAbstractAspect)
diff --git a/src/core/aspects/qaspectmanager.cpp b/src/core/aspects/qaspectmanager.cpp
index 578ff9411..e6752f19c 100644
--- a/src/core/aspects/qaspectmanager.cpp
+++ b/src/core/aspects/qaspectmanager.cpp
@@ -181,9 +181,18 @@ void QAspectManager::exec()
                 m_serviceLocator->service<QAbstractFrameAdvanceService>(QServiceLocator::FrameAdvanceService);
 
         // Start the frameAdvanceService if we're about to enter the running loop
-        if (m_runMainLoop.load())
+        bool needsShutdown = false;
+        if (m_runMainLoop.load()) {
+            needsShutdown = true;
             frameAdvanceService->start();
 
+            // We are about to enter the main loop. Give aspects a chance to do any last
+            // pieces of initialization
+            qCDebug(Aspects) << "Calling onStartup() for each aspect";
+            Q_FOREACH (QAbstractAspect *aspect, m_aspects)
+                aspect->onStartup();
+        }
+
         // Only enter main render loop once the renderer and other aspects are initialized
         while (m_runMainLoop.load())
         {
@@ -200,6 +209,14 @@ void QAspectManager::exec()
             // Process any pending events
             eventLoop.processEvents();
         }
+
+        if (needsShutdown) {
+            // Give aspects a chance to perform any shutdown actions. This may include unqueuing
+            // any blocking work on the main thread that could potentially deadlock during shutdown.
+            qCDebug(Aspects) << "Calling onShutdown() for each aspect";
+            Q_FOREACH (QAbstractAspect *aspect, m_aspects)
+                aspect->onShutdown();
+        }
     }
     qCDebug(Aspects) << Q_FUNC_INFO << "Exiting event loop";