Speed up object creation with lots of id name objects

In the common case when objects are referenced by id, we don't need the
QQmlContextData's property name cache for the lookup. Instead of bindings
we resolve the id to an integer at type compilation time. Therefore we can
delay the population of the QQmlContextData's propertyNames until we need it
and therefore safe time on startup.

Change-Id: I2e8eeb51b1ac92f230059be3467f9a1e00fdbbef
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

3 files changed, 44 insertions, 32 deletions

diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index 1005d097d2..e641226b90 100644
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -305,12 +305,10 @@ void QQmlContext::setContextProperty(const QString &name, const QVariant &value)
         }
     }
 
-    if (data->propertyNames.isEmpty())
-        data->propertyNames = QV4::IdentifierHash<int>(QV8Engine::getV4(engine()->handle()));
-
-    int idx = data->propertyNames.value(name);
+    QV4::IdentifierHash<int> &properties = data->propertyNames();
+    int idx = properties.value(name);
     if (idx == -1) {
-        data->propertyNames.add(name, data->idValueCount + d->propertyValues.count());
+        properties.add(name, data->idValueCount + d->propertyValues.count());
         d->propertyValues.append(value);
 
         data->refreshExpressions();
@@ -343,12 +341,11 @@ void QQmlContext::setContextProperty(const QString &name, QObject *value)
         return;
     }
 
-    if (data->propertyNames.isEmpty())
-        data->propertyNames = QV4::IdentifierHash<int>(QV8Engine::getV4(engine()->handle()));
-    int idx = data->propertyNames.value(name);
+    QV4::IdentifierHash<int> &properties = data->propertyNames();
+    int idx = properties.value(name);
 
     if (idx == -1) {
-        data->propertyNames.add(name, data->idValueCount + d->propertyValues.count());
+        properties.add(name, data->idValueCount + d->propertyValues.count());
         d->propertyValues.append(QVariant::fromValue(value));
 
         data->refreshExpressions();
@@ -370,8 +367,9 @@ QVariant QQmlContext::contextProperty(const QString &name) const
 
     QQmlContextData *data = d->data;
 
-    if (data->propertyNames.count())
-        idx = data->propertyNames.value(name);
+    const QV4::IdentifierHash<int> &properties = data->propertyNames();
+    if (properties.count())
+        idx = properties.value(name);
 
     if (idx == -1) {
         if (data->contextObject) {
@@ -764,31 +762,29 @@ void QQmlContextData::setIdProperty(int idx, QObject *obj)
 
 void QQmlContextData::setIdPropertyData(const QVector<ObjectIdMapping> &data)
 {
-    Q_ASSERT(propertyNames.isEmpty());
-    propertyNames = QV4::IdentifierHash<int>(QV8Engine::getV4(engine->handle()));
-    for (QVector<ObjectIdMapping>::ConstIterator it = data.begin(), end = data.end();
-         it != end; ++it)
-        propertyNames.add(it->name, it->id);
-
+    Q_ASSERT(idObjectNames.isEmpty());
+    idObjectNames = data;
+    Q_ASSERT(propertyNameCache.isEmpty());
     idValueCount = data.count();
     idValues = new ContextGuard[idValueCount];
 }
 
 QString QQmlContextData::findObjectId(const QObject *obj) const
 {
-    if (propertyNames.isEmpty())
+    const QV4::IdentifierHash<int> &properties = propertyNames();
+    if (propertyNameCache.isEmpty())
         return QString();
 
     for (int ii = 0; ii < idValueCount; ii++) {
         if (idValues[ii] == obj)
-            return propertyNames.findId(ii);
+            return properties.findId(ii);
     }
 
     if (publicContext) {
         QQmlContextPrivate *p = QQmlContextPrivate::get(publicContext);
         for (int ii = 0; ii < p->propertyValues.count(); ++ii)
             if (p->propertyValues.at(ii) == QVariant::fromValue((QObject *)obj))
-                return propertyNames.findId(ii);
+                return properties.findId(ii);
     }
 
     if (linkedContext)
@@ -808,4 +804,16 @@ QQmlContextPrivate *QQmlContextData::asQQmlContextPrivate()
     return QQmlContextPrivate::get(asQQmlContext());
 }
 
+QV4::IdentifierHash<int> &QQmlContextData::propertyNames() const
+{
+    if (propertyNameCache.isEmpty()) {
+        propertyNameCache = QV4::IdentifierHash<int>(QV8Engine::getV4(engine->handle()));
+        for (QVector<ObjectIdMapping>::ConstIterator it = idObjectNames.begin(), end = idObjectNames.end();
+             it != end; ++it)
+            propertyNameCache.add(it->name, it->id);
+        idObjectNames.clear();
+    }
+    return propertyNameCache;
+}
+
 QT_END_NAMESPACE
diff --git a/src/qml/qml/qqmlcontext_p.h b/src/qml/qml/qqmlcontext_p.h
index f0e0ab26c6..ddf7d5de75 100644
--- a/src/qml/qml/qqmlcontext_p.h
+++ b/src/qml/qml/qqmlcontext_p.h
@@ -144,8 +144,17 @@ public:
     // Compilation unit for contexts that belong to a compiled type.
     QQmlRefPointer<QV4::CompiledData::CompilationUnit> typeCompilationUnit;
 
-    // Property name cache
-    QV4::IdentifierHash<int> propertyNames;
+    struct ObjectIdMapping {
+        ObjectIdMapping() : id(-1) {}
+        ObjectIdMapping(const QString &name, int id)
+            : name(name), id(id) {}
+        QString name;
+        int id;
+    };
+
+    mutable QVector<ObjectIdMapping> idObjectNames;
+    mutable QV4::IdentifierHash<int> propertyNameCache;
+    QV4::IdentifierHash<int> &propertyNames() const;
 
     // Context object
     QObject *contextObject;
@@ -188,13 +197,6 @@ public:
         QFlagPointer<QQmlContextData> context;
         QQmlNotifier bindings;
     };
-    struct ObjectIdMapping {
-        ObjectIdMapping() : id(-1) {}
-        ObjectIdMapping(const QString &name, int id)
-            : name(name), id(id) {}
-        QString name;
-        int id;
-    };
     ContextGuard *idValues;
     int idValueCount;
     void setIdProperty(int, QObject *);
diff --git a/src/qml/qml/qqmlcontextwrapper.cpp b/src/qml/qml/qqmlcontextwrapper.cpp
index 2498e5acc9..7aca9ad6c2 100644
--- a/src/qml/qml/qqmlcontextwrapper.cpp
+++ b/src/qml/qml/qqmlcontextwrapper.cpp
@@ -199,8 +199,9 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
 
     while (context) {
         // Search context properties
-        if (context->propertyNames.count()) {
-            int propertyIdx = context->propertyNames.value(name);
+        const QV4::IdentifierHash<int> &properties = context->propertyNames();
+        if (properties.count()) {
+            int propertyIdx = properties.value(name);
 
             if (propertyIdx != -1) {
 
@@ -308,8 +309,9 @@ void QmlContextWrapper::put(Managed *m, String *name, const Value &value)
     QObject *scopeObject = wrapper->getScopeObject();
 
     while (context) {
+        const QV4::IdentifierHash<int> &properties = context->propertyNames();
         // Search context properties
-        if (context->propertyNames.count() && -1 != context->propertyNames.value(name))
+        if (properties.count() && properties.value(name) != -1)
             return;
 
         // Search scope object