Add qmlClearRegisteredTypes Function

Registered types are stored in a global static variable, not on an
engine instance. For applications managing multiple engines over their
lifetime, there needs to be a way to clear the existing types so they
can register new ones and avoid memory leaks.

Task-Number: QTBUG-28572
Change-Id: Ic70a4dd1e29d99399b21fb42eaf10d4a52bf2adf
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>

8 files changed, 58 insertions, 3 deletions

diff --git a/src/qml/doc/src/qmlfunctions.qdoc b/src/qml/doc/src/qmlfunctions.qdoc
index 976403adea..386f9f49df 100644
--- a/src/qml/doc/src/qmlfunctions.qdoc
+++ b/src/qml/doc/src/qmlfunctions.qdoc
@@ -47,6 +47,20 @@
   #include <QtQml> to use this macro.
 */
 
+/*!
+  \fn void qmlClearTypeRegistrations()
+  \relates QQmlEngine
+
+  Clears all stored type registrations, such as those produced with \l qmlRegisterType.
+
+  Do not call this function while a QQmlEngine exists or behavior will be undefined.
+  Any existing QQmlEngines must be deleted before calling this function.  This function
+  only affects the application global cache. Delete the QQmlEngine to clear all cached
+  data relating to that engine.
+
+  #include <QtQml> to use this method.
+*/
+
 
 /*!
   \fn int qmlRegisterType(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
diff --git a/src/qml/qml/qqml.h b/src/qml/qml/qqml.h
index 7e6e0d1d36..f04cf7d6fa 100644
--- a/src/qml/qml/qqml.h
+++ b/src/qml/qml/qqml.h
@@ -102,6 +102,8 @@ class QQmlPropertyValueInterceptor;
     listName[listLen+nameLen] = '>'; \
     listName[listLen+nameLen+1] = '\0';
 
+void Q_QML_EXPORT qmlClearTypeRegistrations();
+
 template<typename T>
 int qmlRegisterType()
 {
diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 9d2ad8c4c3..34ebe0a9e2 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -722,17 +722,17 @@ void QQmlData::flushPendingBindingImpl(int coreIndex)
     }
 }
 
+bool QQmlEnginePrivate::baseModulesUninitialized = true;
 void QQmlEnginePrivate::init()
 {
     Q_Q(QQmlEngine);
 
-    static bool firstTime = true;
-    if (firstTime) {
+    if (baseModulesUninitialized) {
         qmlRegisterType<QQmlComponent>("QML", 1, 0, "Component"); // required for the Compiler.
         registerBaseTypes("QtQml", 2, 0); // import which provides language building blocks.
 
         QQmlData::init();
-        firstTime = false;
+        baseModulesUninitialized = false;
     }
 
     qRegisterMetaType<QVariant>();
diff --git a/src/qml/qml/qqmlengine_p.h b/src/qml/qml/qqmlengine_p.h
index b745d6a963..0d852c1c1b 100644
--- a/src/qml/qml/qqmlengine_p.h
+++ b/src/qml/qml/qqmlengine_p.h
@@ -125,6 +125,9 @@ public:
     ~QQmlEnginePrivate();
 
     void init();
+    // No mutex protecting baseModulesUninitialized, because use outside QQmlEngine
+    // is just qmlClearTypeRegistrations (which can't be called while an engine exists)
+    static bool baseModulesUninitialized;
 
     class PropertyCapture {
     public:
diff --git a/src/qml/qml/qqmlimport.cpp b/src/qml/qml/qqmlimport.cpp
index f793ca9604..2fbb614605 100644
--- a/src/qml/qml/qqmlimport.cpp
+++ b/src/qml/qml/qqmlimport.cpp
@@ -163,6 +163,14 @@ QQmlType *getTypeForUrl(const QString &urlString, const QHashedStringRef& typeNa
 
 typedef QMap<QString, QString> StringStringMap;
 Q_GLOBAL_STATIC(StringStringMap, qmlEnginePluginsWithRegisteredTypes); // stores the uri
+void qmlClearEnginePlugins()
+{
+    foreach (const QString &s, qmlEnginePluginsWithRegisteredTypes()->values()) {
+        QPluginLoader loader(s);
+        loader.unload(); // ### Always returns false, worth doing?
+    }
+    qmlEnginePluginsWithRegisteredTypes()->clear();
+}
 
 class QQmlImportNamespace
 {
diff --git a/src/qml/qml/qqmlimport_p.h b/src/qml/qml/qqmlimport_p.h
index 140ca6695e..06b50c09e9 100644
--- a/src/qml/qml/qqmlimport_p.h
+++ b/src/qml/qml/qqmlimport_p.h
@@ -182,6 +182,8 @@ private:
     QQmlEngine *engine;
 };
 
+void qmlClearEnginePlugins();// For internal use by qmlClearRegisteredProperties
+
 QT_END_NAMESPACE
 
 #endif // QQMLIMPORT_P_H
diff --git a/src/qml/qml/qqmlmetatype.cpp b/src/qml/qml/qqmlmetatype.cpp
index 0f3a27aeff..b29df4d252 100644
--- a/src/qml/qml/qqmlmetatype.cpp
+++ b/src/qml/qml/qqmlmetatype.cpp
@@ -46,6 +46,7 @@
 #include <private/qqmlcustomparser_p.h>
 #include <private/qqmlguard_p.h>
 #include <private/qhashedstring_p.h>
+#include <private/qqmlimport_p.h>
 
 #include <QtCore/qdebug.h>
 #include <QtCore/qstringlist.h>
@@ -1068,6 +1069,29 @@ QQmlType *QQmlTypeModuleVersion::type(const QHashedV8String &name) const
     else return 0;
 }
 
+void qmlClearTypeRegistrations() // Declared in qqml.h
+{
+    //Only cleans global static, assumed no running engine
+    QWriteLocker lock(metaTypeDataLock());
+    QQmlMetaTypeData *data = metaTypeData();
+
+    for (int i = 0; i < data->types.count(); ++i)
+        delete data->types.at(i);
+
+    QQmlMetaTypeData::TypeModules::const_iterator i = data->uriToModule.constBegin();
+    for (; i != data->uriToModule.constEnd(); ++i)
+        delete *i;
+
+    data->types.clear();
+    data->idToType.clear();
+    data->nameToType.clear();
+    data->urlToType.clear();
+    data->metaObjectToType.clear();
+    data->uriToModule.clear();
+
+    QQmlEnginePrivate::baseModulesUninitialized = true; //So the engine re-registers its types
+    qmlClearEnginePlugins();
+}
 
 int registerAutoParentFunction(QQmlPrivate::RegisterAutoParent &autoparent)
 {
diff --git a/src/qml/qml/qqmlmetatype_p.h b/src/qml/qml/qqmlmetatype_p.h
index 497afffb5d..12901e8c58 100644
--- a/src/qml/qml/qqmlmetatype_p.h
+++ b/src/qml/qml/qqmlmetatype_p.h
@@ -231,6 +231,7 @@ private:
     friend int registerSingletonType(const QQmlPrivate::RegisterSingletonType &);
     friend int registerInterface(const QQmlPrivate::RegisterInterface &);
     friend int registerCompositeType(const QQmlPrivate::RegisterCompositeType &);
+    friend void qmlClearTypeRegistrations();
     QQmlType(int, const QQmlPrivate::RegisterInterface &);
     QQmlType(int, const QString &, const QQmlPrivate::RegisterSingletonType &);
     QQmlType(int, const QString &, const QQmlPrivate::RegisterType &);
@@ -259,6 +260,7 @@ private:
     //Used by register functions and creates the QQmlTypeModule for them
     friend void addTypeToData(QQmlType* type, QQmlMetaTypeData *data);
     friend struct QQmlMetaTypeData;
+    friend void qmlClearTypeRegistrations();
 
     QQmlTypeModule();
     ~QQmlTypeModule();