Clean up manual refcounting of compilation units

Replace manual use in QQmlData and QQmlData::DeferredData with
QQmlRefPointer.

Due to forward declaration trouble this required declaring a non-inline
constructor/destructor for QQmlData and DeferedData and disabling
copying, so that not every C++ compilation unit including qqmldata_p.h
needs to instantiate the QQmlRefPointer destructor and thus know whether
QV4::CompiledData::CompilationUnit has release(), etc. The out-of-line
declarations however should not have any negative impact as the only
call sites are within qqmlengine.cpp, too.

Change-Id: I2e8295cb0d7f876a5d7d18765dbac285184e6c99
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/qml/qml/qqmldata_p.h

@@ -56,6 +56,7 @@
 #include <private/qqmlpropertyindex_p.h>
 #include <private/qv4value_p.h>
 #include <private/qv4persistent_p.h>
+#include <private/qqmlrefcount_p.h>
 #include <qjsengine.h>
 #include <qvector.h>
 
@@ -116,6 +117,7 @@ class Q_QML_PRIVATE_EXPORT QQmlData : public QAbstractDeclarativeData
 {
 public:
     QQmlData();
+    ~QQmlData();
 
     static inline void init() {
         static bool initialized = false;
@@ -219,12 +221,15 @@ class Q_QML_PRIVATE_EXPORT QQmlData : public QAbstractDeclarativeData
     quint32 jsEngineId; // id of the engine that created the jsWrapper
 
     struct DeferredData {
+        DeferredData();
+        ~DeferredData();
         unsigned int deferredIdx;
         QMultiHash<int, const QV4::CompiledData::Binding *> bindings;
-        QV4::CompiledData::CompilationUnit *compilationUnit;//Not always the same as the other compilation unit
+        QQmlRefPointer<QV4::CompiledData::CompilationUnit> compilationUnit;//Not always the same as the other compilation unit
         QQmlContextData *context;//Could be either context or outerContext
+        Q_DISABLE_COPY(DeferredData);
     };
-    QV4::CompiledData::CompilationUnit *compilationUnit;
+    QQmlRefPointer<QV4::CompiledData::CompilationUnit> compilationUnit;
     QVector<DeferredData *> deferredData;
 
     void deferData(int objectIndex, QV4::CompiledData::CompilationUnit *, QQmlContextData *);
@@ -299,6 +304,7 @@ class Q_QML_PRIVATE_EXPORT QQmlData : public QAbstractDeclarativeData
         const BindingBitsType *bits = (bindingBitsArraySize == InlineBindingArraySize) ? bindingBitsValue : bindingBits;
         return bits[offset] & bitFlagForBit(bit);
     }
+    Q_DISABLE_COPY(QQmlData);
 };
 
 bool QQmlData::wasDeleted(const QObject *object)

src/qml/qml/qqmlengine.cpp

@@ -746,13 +746,17 @@ QQmlData::QQmlData()
       hasInterceptorMetaObject(false), hasVMEMetaObject(false), parentFrozen(false),
       bindingBitsArraySize(InlineBindingArraySize), notifyList(0),
       bindings(0), signalHandlers(0), nextContextObject(0), prevContextObject(0),
-      lineNumber(0), columnNumber(0), jsEngineId(0), compilationUnit(0),
+      lineNumber(0), columnNumber(0), jsEngineId(0),
       propertyCache(0), guards(0), extendedData(0)
 {
     memset(bindingBitsValue, 0, sizeof(bindingBitsValue));
     init();
 }
 
+QQmlData::~QQmlData()
+{
+}
+
 void QQmlData::destroyed(QAbstractDeclarativeData *d, QObject *o)
 {
     QQmlData *ddata = static_cast<QQmlData *>(d);
@@ -924,6 +928,14 @@ void QQmlData::flushPendingBindingImpl(QQmlPropertyIndex index)
                             QQmlPropertyData::DontRemoveBinding);
 }
 
+QQmlData::DeferredData::DeferredData()
+{
+}
+
+QQmlData::DeferredData::~DeferredData()
+{
+}
+
 bool QQmlEnginePrivate::baseModulesUninitialized = true;
 void QQmlEnginePrivate::init()
 {
@@ -1651,7 +1663,6 @@ void QQmlData::deferData(int objectIndex, QV4::CompiledData::CompilationUnit *co
     QQmlData::DeferredData *deferData = new QQmlData::DeferredData;
     deferData->deferredIdx = objectIndex;
     deferData->compilationUnit = compilationUnit;
-    deferData->compilationUnit->addref();
     deferData->context = context;
 
     const QV4::CompiledData::Object *compiledObject = compilationUnit->objectAt(objectIndex);
@@ -1673,7 +1684,6 @@ void QQmlData::releaseDeferredData()
     while (it != deferredData.end()) {
         DeferredData *deferData = *it;
         if (deferData->bindings.isEmpty()) {
-            deferData->compilationUnit->release();
             delete deferData;
             it = deferredData.erase(it);
         } else {
@@ -1751,10 +1761,7 @@ void QQmlData::destroyed(QObject *object)
     if (bindings && !bindings->ref.deref())
         delete bindings;
 
-    if (compilationUnit) {
-        compilationUnit->release();
-        compilationUnit = 0;
-    }
+    compilationUnit = nullptr;
 
     releaseDeferredData();
 

src/qml/qml/qqmlobjectcreator.cpp

@@ -203,10 +203,7 @@ QObject *QQmlObjectCreator::create(int subComponentIndex, QObject *parent, QQmlI
     if (instance) {
         QQmlData *ddata = QQmlData::get(instance);
         Q_ASSERT(ddata);
-        if (ddata->compilationUnit)
-            ddata->compilationUnit->release();
         ddata->compilationUnit = compilationUnit;
-        ddata->compilationUnit->addref();
     }
 
     if (topLevelCreator)

src/qml/qml/qqmlobjectcreator_p.h

@@ -137,7 +137,7 @@ class Q_QML_PRIVATE_EXPORT QQmlObjectCreator
 
     QQmlEngine *engine;
     QV4::ExecutionEngine *v4;
-    QV4::CompiledData::CompilationUnit *compilationUnit;
+    QQmlRefPointer<QV4::CompiledData::CompilationUnit> compilationUnit;
     const QV4::CompiledData::Unit *qmlUnit;
     QQmlGuardedContextData parentContext;
     QQmlContextData *context;