Emit Component.onDestruction before context is invalidated

When a component no longer has any live references, emit the
destruction signal immediately so that handlers are run before the
associated V8 resources are invalidated.  Also, when the root
context of the engine is destroyed, emit the destruction signal
before destroying any resources needed to process the resulting
binding invocations.

Change-Id: I722dd6e4b60c499b533fc45e33b61e95bca6187f
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>

diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index cbb8430..7e15993 100644 (file)
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -513,7 +513,8 @@ QObject *QQmlContextPrivate::context_at(QQmlListProperty<QObject> *prop, int ind
 
 QQmlContextData::QQmlContextData()
 : parent(0), engine(0), isInternal(false), ownedByParent(false), isJSContext(false), 
-  isPragmaLibraryContext(false), unresolvedNames(false), publicContext(0), activeVMEData(0),
+  isPragmaLibraryContext(false), unresolvedNames(false), hasEmittedDestruction(false),
+  publicContext(0), activeVMEData(0),
   propertyNames(0), contextObject(0), imports(0), childContexts(0), nextChild(0), prevChild(0),
   expressions(0), contextObjects(0), contextGuards(0), idValues(0), idValueCount(0), linkedContext(0),
   componentAttached(0), v4bindings(0), v8bindings(0)
@@ -522,25 +523,45 @@ QQmlContextData::QQmlContextData()
 
 QQmlContextData::QQmlContextData(QQmlContext *ctxt)
 : parent(0), engine(0), isInternal(false), ownedByParent(false), isJSContext(false), 
-  isPragmaLibraryContext(false), unresolvedNames(false), publicContext(ctxt), activeVMEData(0),
+  isPragmaLibraryContext(false), unresolvedNames(false), hasEmittedDestruction(false),
+  publicContext(ctxt), activeVMEData(0),
   propertyNames(0), contextObject(0), imports(0), childContexts(0), nextChild(0), prevChild(0),
   expressions(0), contextObjects(0), contextGuards(0), idValues(0), idValueCount(0), linkedContext(0),
   componentAttached(0), v4bindings(0), v8bindings(0)
 {
 }
 
-void QQmlContextData::invalidate()
+void QQmlContextData::emitDestruction()
 {
-    while (componentAttached) {
-        QQmlComponentAttached *a = componentAttached;
-        componentAttached = a->next;
-        if (componentAttached) componentAttached->prev = &componentAttached;
+    if (!hasEmittedDestruction) {
+        hasEmittedDestruction = true;
+
+        // Emit the destruction signal - must be emitted before invalidate so that the
+        // context is still valid if bindings or resultant expression evaluation requires it
+        if (engine) {
+            while (componentAttached) {
+                QQmlComponentAttached *a = componentAttached;
+                componentAttached = a->next;
+                if (componentAttached) componentAttached->prev = &componentAttached;
 
-        a->next = 0;
-        a->prev = 0;
+                a->next = 0;
+                a->prev = 0;
+
+                emit a->destruction();
+            }
 
-        emit a->destruction();
+            QQmlContextData * child = childContexts;
+            while (child) {
+                child->emitDestruction();
+                child = child->nextChild;
+            }
+        }
     }
+}
+
+void QQmlContextData::invalidate()
+{
+    emitDestruction();
 
     while (childContexts) {
         if (childContexts->ownedByParent) {
@@ -563,18 +584,7 @@ void QQmlContextData::invalidate()
 
 void QQmlContextData::clearContext()
 {
-    if (engine) {
-        while (componentAttached) {
-            QQmlComponentAttached *a = componentAttached;
-            componentAttached = a->next;
-            if (componentAttached) componentAttached->prev = &componentAttached;
-
-            a->next = 0;
-            a->prev = 0;
-
-            emit a->destruction();
-        }
-    }
+    emitDestruction();
 
     QQmlAbstractExpression *expression = expressions;
     while (expression) {

diff --git a/src/qml/qml/qqmlcontext_p.h b/src/qml/qml/qqmlcontext_p.h
index 97bc04b..1f1c601 100644 (file)
--- a/src/qml/qml/qqmlcontext_p.h
+++ b/src/qml/qml/qqmlcontext_p.h
@@ -118,6 +118,7 @@ class Q_QML_EXPORT QQmlContextData
 public:
     QQmlContextData();
     QQmlContextData(QQmlContext *);
+    void emitDestruction();
     void clearContext();
     void destroy();
     void invalidate();
@@ -146,7 +147,8 @@ public:
     quint32 isJSContext:1;
     quint32 isPragmaLibraryContext:1;
     quint32 unresolvedNames:1; // True if expressions in this context failed to resolve a toplevel name
-    quint32 dummy:27;
+    quint32 hasEmittedDestruction:1;
+    quint32 dummy:26;
     QQmlContext *publicContext;
 
     // VME data that is constructing this context if any

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index c79e756..2717ed3 100644 (file)
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -575,6 +575,11 @@ QQmlEngine::~QQmlEngine()
         QQmlEngineDebugService::instance()->remEngine(this);
     }
 
+    // Emit onDestruction signals for the root context before
+    // we destroy the contexts, engine, Module APIs etc. that
+    // may be required to handle the destruction signal.
+    QQmlContextData::get(rootContext())->emitDestruction();
+
     // if we are the parent of any of the qobject module api instances,
     // we need to remove them from our internal list, in order to prevent
     // a segfault in engine private dtor.

diff --git a/src/qml/qml/v8/qv8qobjectwrapper.cpp b/src/qml/qml/v8/qv8qobjectwrapper.cpp
index f2acac5..7e7b6eb 100644 (file)
--- a/src/qml/qml/v8/qv8qobjectwrapper.cpp
+++ b/src/qml/qml/v8/qv8qobjectwrapper.cpp
@@ -1160,6 +1160,9 @@ void QV8QObjectWrapper::deleteWeakQObject(QV8QObjectResource *resource)
 
             ddata->v8object.Clear();
             if (!object->parent() && !ddata->indestructible) {
+                // This object is notionally destroyed now
+                if (ddata->ownContext && ddata->context)
+                    ddata->context->emitDestruction();
                 ddata->isQueuedForDeletion = true;
                 object->deleteLater();
             }

diff --git a/tests/auto/qml/qqmlcomponent/data/onDestructionCount.qml b/tests/auto/qml/qqmlcomponent/data/onDestructionCount.qml
new file mode 100644 (file)
index 0000000..3938acf
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/onDestructionCount.qml
@@ -0,0 +1,16 @@
+import QtQuick 2.0
+
+Item {
+    Component {
+        id: internalComponent
+
+        Item {
+            Component.onDestruction: console.warn('Component.onDestruction')
+        }
+    }
+
+    Component.onCompleted: {
+        internalComponent.createObject()
+        gc()
+    }
+}

diff --git a/tests/auto/qml/qqmlcomponent/data/onDestructionLookup.qml b/tests/auto/qml/qqmlcomponent/data/onDestructionLookup.qml
new file mode 100644 (file)
index 0000000..a49a86e
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/onDestructionLookup.qml
@@ -0,0 +1,25 @@
+import QtQuick 2.0
+
+Item {
+    id: root
+
+    property bool success: false
+
+    Component {
+        id: internalComponent
+
+        Item {
+            id: internalRoot
+
+            property string foo: ''
+
+            Component.onCompleted: { internalRoot.foo = 'bar' }
+            Component.onDestruction: { root.success = (internalRoot.foo == 'bar') }
+        }
+    }
+
+    Component.onCompleted: {
+        internalComponent.createObject()
+        gc()
+    }
+}

diff --git a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
index b534d0c..bf76ed9 100644 (file)
--- a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
+++ b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
@@ -112,6 +112,8 @@ private slots:
     void async();
     void asyncHierarchy();
     void componentUrlCanonicalization();
+    void onDestructionLookup();
+    void onDestructionCount();
 
 private:
     QQmlEngine engine;
@@ -366,6 +368,47 @@ void tst_qqmlcomponent::componentUrlCanonicalization()
     }
 }
 
+void tst_qqmlcomponent::onDestructionLookup()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("onDestructionLookup.qml"));
+    QScopedPointer<QObject> object(component.create());
+    QVERIFY(object != 0);
+    QVERIFY(object->property("success").toBool());
+}
+
+void tst_qqmlcomponent::onDestructionCount()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("onDestructionCount.qml"));
+
+    QLatin1String warning("Component.onDestruction");
+
+    {
+        // Warning should be emitted during create()
+        QTest::ignoreMessage(QtWarningMsg, warning.data());
+
+        QScopedPointer<QObject> object(component.create());
+        QVERIFY(object != 0);
+    }
+
+    // Warning should not be emitted any further
+    QCOMPARE(engine.outputWarningsToStandardError(), true);
+
+    warnings.clear();
+    QtMsgHandler old = qInstallMsgHandler(msgHandler);
+
+    QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
+    QCoreApplication::processEvents();
+
+    qInstallMsgHandler(old);
+
+    engine.setOutputWarningsToStandardError(false);
+    QCOMPARE(engine.outputWarningsToStandardError(), false);
+
+    QCOMPARE(warnings.count(), 0);
+}
+
 QTEST_MAIN(tst_qqmlcomponent)
 
 #include "tst_qqmlcomponent.moc"

diff --git a/tests/auto/qml/qqmlecmascript/data/OnDestructionComponent.qml b/tests/auto/qml/qqmlecmascript/data/OnDestructionComponent.qml
new file mode 100644 (file)
index 0000000..dcf4672
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/OnDestructionComponent.qml
@@ -0,0 +1,9 @@
+import QtQuick 2.0
+import Qt.test 1.0 as ModApi
+
+Item {
+    id: sec
+
+    property int a: 10
+    Component.onDestruction: ModApi.setSpecificProperty(sec, "a", 20);
+}

diff --git a/tests/auto/qml/qqmlecmascript/data/onDestruction.qml b/tests/auto/qml/qqmlecmascript/data/onDestruction.qml
new file mode 100644 (file)
index 0000000..b2963a1
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/onDestruction.qml
@@ -0,0 +1,18 @@
+import QtQuick 2.0
+
+Item {
+    id: root
+
+    property Component comp: OnDestructionComponent {
+        property int b: 50
+        onParentChanged: b += a
+    }
+
+    property Item compInstance
+
+    Component.onCompleted: {
+        compInstance = comp.createObject(root);
+        compInstance.destroy();
+    }
+}
+

diff --git a/tests/auto/qml/qqmlecmascript/testtypes.h b/tests/auto/qml/qqmlecmascript/testtypes.h
index f39d5d9..a289d97 100644 (file)
--- a/tests/auto/qml/qqmlecmascript/testtypes.h
+++ b/tests/auto/qml/qqmlecmascript/testtypes.h
@@ -1021,6 +1021,8 @@ public:
     Q_INVOKABLE void setTrackedObjectProperty(const QString &propName) const { m_trackedObject->setProperty(qPrintable(propName), QVariant(5)); }
     Q_INVOKABLE QVariant trackedObjectProperty(const QString &propName) const { return m_trackedObject->property(qPrintable(propName)); }
 
+    Q_INVOKABLE void setSpecificProperty(QObject *obj, const QString & propName, const QVariant & v) const { obj->setProperty(qPrintable(propName), v); }
+
     int qobjectTestProperty() const { return m_testProperty; }
     void setQObjectTestProperty(int tp) { m_testProperty = tp; emit qobjectTestPropertyChanged(tp); }
 

diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 4e7f1a2..11819c5 100644 (file)
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -257,6 +257,8 @@ private slots:
     void tryStatement();
     void replaceBinding();
     void deleteRootObjectInCreation();
+    void onDestruction();
+
 private:
     static void propertyVarWeakRefCallback(v8::Persistent<v8::Value> object, void* parameter);
     QQmlEngine engine;
@@ -6632,6 +6634,30 @@ void tst_qqmlecmascript::deleteRootObjectInCreation()
     delete obj;
 }
 
+void tst_qqmlecmascript::onDestruction()
+{
+    {
+        // Delete object manually to invoke the associated handlers,
+        // prior to engine destruction.
+        QQmlEngine engine;
+        QQmlComponent c(&engine, testFileUrl("onDestruction.qml"));
+        QObject *obj = c.create();
+        QVERIFY(obj != 0);
+        delete obj;
+    }
+
+    {
+        // In this case, the teardown of the engine causes deletion
+        // of contexts and child items.  This triggers the
+        // onDestruction handler of a (previously .destroy()ed)
+        // component instance.  This shouldn't crash.
+        QQmlEngine engine;
+        QQmlComponent c(&engine, testFileUrl("onDestruction.qml"));
+        QObject *obj = c.create();
+        QVERIFY(obj != 0);
+    }
+}
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"