Introduce optimized Handle class for QScriptContextPrivate usage.

New class depending on parameter behaves as v8::Local or as
v8::Persistent.

According to benchmarks, The QSCP::Handle class together with
QSCP::Stack and QSCP::Heap classes gives us QObject bindings
speedup from 2-12% (it reduce significantly v8::Persistent
usage).

4 files changed, 185 insertions, 27 deletions

diff --git a/src/script/api/qscriptclass.cpp b/src/script/api/qscriptclass.cpp
index ad6d8ac..0e5aac6 100644
--- a/src/script/api/qscriptclass.cpp
+++ b/src/script/api/qscriptclass.cpp
@@ -249,7 +249,7 @@ v8::Handle<v8::Value> QScriptClassObject::call(const v8::Arguments& args)
     if (!userCallback->supportsExtension(QScriptClass::Callable))
         return handleScope.Close(v8::ThrowException(v8::Exception::TypeError(v8::String::New("QScriptClass for object doesn't support Callable extension"))));
 
-    v8::Handle<v8::Object> thisObject;
+    v8::Local<v8::Object> thisObject;
 
     // v8 doesn't create a new Object to put in This() when the constructor call came from
     // a callback registered with SetCallAsFunctionHandler().
diff --git a/src/script/api/qscriptcontext_impl_p.h b/src/script/api/qscriptcontext_impl_p.h
index 266f2d0..b2305e0 100644
--- a/src/script/api/qscriptcontext_impl_p.h
+++ b/src/script/api/qscriptcontext_impl_p.h
@@ -51,10 +51,10 @@ inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, Q
 
 inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Handle<v8::Value> callee, v8::Handle<v8::Object> customThisObject)
     : m_allocation(type), q_ptr(this), engine(engine), arguments(args), accessorInfo(0),
-      context(v8::Persistent<v8::Context>::New(v8::Context::NewFunctionContext())),
-      inheritedScope(v8::Persistent<v8::Context>::New(v8::Context::GetCallerContext())),
-      parent(engine->setCurrentQSContext(this)), previous(0), m_thisObject(v8::Persistent<v8::Object>::New(customThisObject)),
-      m_callee(v8::Persistent<v8::Value>::New(callee)), hasArgumentGetter(false)
+      context(type, v8::Context::NewFunctionContext()),
+      inheritedScope(type, v8::Context::GetCallerContext()),
+      parent(engine->setCurrentQSContext(this)), previous(0), m_thisObject(type, customThisObject),
+      m_callee(type, callee), hasArgumentGetter(false)
 {
     Q_ASSERT(engine);
     Q_ASSERT(parent);
@@ -63,8 +63,8 @@ inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, Q
 
 inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, const v8::AccessorInfo *accessor)
     : m_allocation(type), q_ptr(this), engine(engine), arguments(0), accessorInfo(accessor),
-      context(v8::Persistent<v8::Context>::New(v8::Context::NewFunctionContext())),
-      inheritedScope(v8::Persistent<v8::Context>::New(v8::Context::GetCallerContext())),
+      context(type, v8::Context::NewFunctionContext()),
+      inheritedScope(type, v8::Context::GetCallerContext()),
       parent(engine->setCurrentQSContext(this)), previous(0), hasArgumentGetter(false)
 {
     Q_ASSERT(engine);
@@ -74,7 +74,8 @@ inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, Q
 
 inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, v8::Handle<v8::Context> context)
     : m_allocation(type), q_ptr(this), engine(engine), arguments(0), accessorInfo(0),
-      context(v8::Persistent<v8::Context>::New(context)), parent(engine->setCurrentQSContext(this)),
+      context(type, context),
+      parent(engine->setCurrentQSContext(this)),
       previous(0), hasArgumentGetter(false)
 {
     Q_ASSERT(engine);
@@ -84,7 +85,39 @@ inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, Q
 
 inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptContextPrivate *parent, v8::Handle<v8::StackFrame> frame)
     : m_allocation(type), q_ptr(this), engine(parent->engine), arguments(0), accessorInfo(0),
-      parent(parent), previous(0), frame(v8::Persistent<v8::StackFrame>::New(frame)), hasArgumentGetter(false)
+      parent(parent), previous(0), frame(type, frame), hasArgumentGetter(false)
+{
+    Q_ASSERT(engine);
+    Q_ASSERT(parent);
+}
+
+inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Local<v8::Value> callee, v8::Local<v8::Object> customThisObject)
+    : m_allocation(type), q_ptr(this), engine(engine), arguments(args), accessorInfo(0),
+      context(type, v8::Context::NewFunctionContext()),
+      inheritedScope(type, v8::Context::GetCallerContext()),
+      parent(engine->setCurrentQSContext(this)), previous(0), m_thisObject(type, customThisObject),
+      m_callee(type, callee), hasArgumentGetter(false)
+{
+    Q_ASSERT(engine);
+    Q_ASSERT(parent);
+    context->Enter();
+}
+
+
+inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, v8::Local<v8::Context> context)
+    : m_allocation(type), q_ptr(this), engine(engine), arguments(0), accessorInfo(0),
+      context(type, context),
+      parent(engine->setCurrentQSContext(this)),
+      previous(0), hasArgumentGetter(false)
+{
+    Q_ASSERT(engine);
+    Q_ASSERT(parent);
+    context->Enter();
+}
+
+inline QScriptContextPrivate::QScriptContextPrivate(const AllocationType type, QScriptContextPrivate *parent, v8::Local<v8::StackFrame> frame)
+    : m_allocation(type), q_ptr(this), engine(parent->engine), arguments(0), accessorInfo(0),
+      parent(parent), previous(0), frame(type, frame), hasArgumentGetter(false)
 {
     Q_ASSERT(engine);
     Q_ASSERT(parent);
@@ -166,7 +199,7 @@ inline v8::Handle<v8::Object> QScriptContextPrivate::thisObject() const
     // setThisObject() doesn't work for native functions, but the constructor for native function
     // can set m_thisObject, so we give it higher precedence.
     if (!m_thisObject.IsEmpty()) {
-        return m_thisObject;
+        return m_thisObject.v8Handle();
     } else if (isNativeFunction()) {
         return arguments->This();
     } else if (isNativeAccessor()) {
@@ -197,8 +230,7 @@ inline void QScriptContextPrivate::setThisObject(QScriptValuePrivate *newThis)
         return;
     }
 
-    m_thisObject.Dispose();
-    m_thisObject = v8::Persistent<v8::Object>::New(*newThis);
+    m_thisObject = static_cast<v8::Handle<v8::Object> >(*newThis);
 }
 
 
@@ -206,7 +238,7 @@ inline QScriptPassPointer<QScriptValuePrivate> QScriptContextPrivate::callee() c
 {
     if (isNativeFunction()) {
         if (!m_callee.IsEmpty())
-            return new QScriptValuePrivate(engine, m_callee);
+            return new QScriptValuePrivate(engine, m_callee.v8Handle());
         return new QScriptValuePrivate(engine, arguments->Callee());
     }
 
@@ -271,7 +303,7 @@ inline QScriptValueList QScriptContextPrivate::scopeChain() const
         list.append(QScriptValuePrivate::get(activationObject()));
 
     if (!inheritedScope.IsEmpty()) {
-        v8::Handle<v8::Context> current = inheritedScope;
+        v8::Handle<v8::Context> current = inheritedScope.v8Handle();
         do {
             v8::Handle<v8::Object> object = current->GetExtensionObject();
             list.append(QScriptValuePrivate::get(new QScriptValuePrivate(engine, object)));
@@ -290,8 +322,8 @@ inline QScriptValueList QScriptContextPrivate::scopeChain() const
 inline void QScriptContextPrivate::pushScope(QScriptValuePrivate *object)
 {
     v8::Handle<v8::Object> objectHandle(v8::Object::Cast(*object->asV8Value(engine)));
-    v8::Handle<v8::Context> scopeContext = v8::Context::NewScopeContext(objectHandle);
-    scopes.append(v8::Persistent<v8::Context>::New(scopeContext));
+    Handle<v8::Context> scopeContext(m_allocation, v8::Context::NewScopeContext(objectHandle));
+    scopes.append(scopeContext);
     scopeContext->Enter();
 }
 
@@ -303,7 +335,7 @@ inline QScriptPassPointer<QScriptValuePrivate> QScriptContextPrivate::popScope()
         Q_UNIMPLEMENTED();
         return InvalidValue();
     }
-    v8::Persistent<v8::Context> scopeContext = scopes.takeLast();
+    Handle<v8::Context> scopeContext = scopes.takeLast();
     v8::Handle<v8::Object> object = scopeContext->GetExtensionObject();
     scopeContext->Exit();
     scopeContext.Dispose();
@@ -384,7 +416,7 @@ inline QScriptContextPrivate::Stack::Stack(QScriptEnginePrivate *engine) // the
     : QScriptContextPrivate(StackAllocation, engine)
 {}
 
-inline QScriptContextPrivate::Stack::Stack(QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Handle<v8::Value> callee, v8::Handle<v8::Object> customThisObject) // native function context (on the stack)
+inline QScriptContextPrivate::Stack::Stack(QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Local<v8::Value> callee, v8::Local<v8::Object> customThisObject) // native function context (on the stack)
     : QScriptContextPrivate(StackAllocation, engine, args, callee, customThisObject)
 {}
 
diff --git a/src/script/api/qscriptcontext_p.h b/src/script/api/qscriptcontext_p.h
index daac674..d9bd218 100644
--- a/src/script/api/qscriptcontext_p.h
+++ b/src/script/api/qscriptcontext_p.h
@@ -59,9 +59,136 @@ protected:
     inline QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, v8::Handle<v8::Context> context); // from QScriptEngine::pushContext
     inline QScriptContextPrivate(const AllocationType type, QScriptContextPrivate *parent, v8::Handle<v8::StackFrame> frame); // internal, for js frame (allocated in parentContext())
 
+    inline QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Local<v8::Value> callee = v8::Local<v8::Value>(), v8::Local<v8::Object> customThisObject = v8::Local<v8::Object>()); // native function context (on the stack)
+    inline QScriptContextPrivate(const AllocationType type, QScriptEnginePrivate *engine, v8::Local<v8::Context> context); // from QScriptEngine::pushContext
+    inline QScriptContextPrivate(const AllocationType type, QScriptContextPrivate *parent, v8::Local<v8::StackFrame> frame); // internal, for js frame (allocated in parentContext())
 public:
     class Stack;
     class Heap;
+    template<class T>
+    class Handle : protected v8::Handle<T>
+    {
+    public:
+        typedef QScriptContextPrivate::AllocationType Type;
+
+        Handle()
+            : m_type(HeapAllocation) // lazy fall-back to Persistent
+        {}
+
+        Handle(Type type)
+            : m_type(type)
+        {}
+
+        Handle(Type type, v8::Handle<T> handle)
+            : m_type(type)
+        {
+            switch (m_type){
+            case Local: *asLocal() = v8::Local<T>::New(handle); break;
+            case Persistent: *asPersistent() = v8::Persistent<T>::New(handle); break;
+            }
+        }
+
+        Handle(Type type, v8::Local<T> handle)
+            : m_type(type)
+        {
+            switch (m_type){
+            case Local:
+                // We do not need to call Local::New because this local is already protected by
+                // a higher HandleScope that would survive longer than this QScriptContextPrivate
+                *asLocal() = handle;
+                break;
+            case Persistent: *asPersistent() = v8::Persistent<T>::New(handle); break;
+            }
+        }
+
+
+        Handle(const Handle<T>& handle)
+            : v8::Handle<T>(*handle)
+            , m_type(handle.m_type)
+        {
+            switch (m_type){
+            case Local:
+                // The other handle is already protected, its live time would the same or a bit longer
+                // so we do not need Local::New here.
+                break;
+            case Persistent: *asPersistent() = v8::Persistent<T>::New(handle); break;
+            }
+        }
+
+        void operator =(v8::Handle<T> handle)
+        {
+            switch (m_type){
+            case Local: *asLocal() = v8::Local<T>::New(handle); break;
+            case Persistent:
+                asPersistent()->Dispose();
+                *asPersistent() = v8::Persistent<T>::New(handle);
+                break;
+            }
+        }
+
+        void operator =(v8::Local<T> handle)
+        {
+            switch (m_type){
+            case Local:
+                // The other handle is already protected, its live time would the same or a bit longer
+                // so we do not need Local::New here.
+                *asLocal() = handle;
+                break;
+            case Persistent:
+                asPersistent()->Dispose();
+                *asPersistent() = v8::Persistent<T>::New(handle);
+                break;
+            }
+        }
+
+        void operator =(Handle<T> handle)
+        {
+            Q_ASSERT(handle.m_type == m_type);
+            switch (m_type) {
+            case Local:
+                // The other handle is already protected, its live time would the same or a bit longer
+                // so we do not need Local::New here.
+                *asLocal() = *handle.asLocal();
+                break;
+            case Persistent:
+                asPersistent()->Dispose();
+                *asPersistent() = v8::Persistent<T>::New(handle);
+                break;
+            }
+        }
+
+        void Dispose()
+        {
+            if (m_type == Persistent) {
+                asPersistent()->Dispose();
+                // FIXME: maybe it is not needed ?
+                asPersistent()->Clear();
+            }
+        }
+
+        inline T* operator->() const { return v8::Handle<T>::operator ->(); }
+        inline T* operator*() const { return v8::Handle<T>::operator *(); }
+        inline bool IsEmpty() const { return v8::Handle<T>::IsEmpty(); }
+        inline v8::Handle<T> v8Handle() const { return v8::Handle<T>(*this); }
+
+    private:
+        static const int Persistent = QScriptContextPrivate::HeapAllocation;
+        static const int Local = QScriptContextPrivate::StackAllocation;
+        const Type m_type;
+
+        inline v8::Persistent<T> *asPersistent()
+        {
+            Q_ASSERT(m_type == Persistent);
+            return reinterpret_cast<v8::Persistent<T> *>(this);
+        }
+
+        inline v8::Local<T> *asLocal()
+        {
+            Q_ASSERT(m_type == Local);
+            return reinterpret_cast<v8::Local<T> *>(this);
+        }
+    };
+
 
     static QScriptContextPrivate *get(const QScriptContext *q) { Q_ASSERT(q->d_ptr); return q->d_ptr; }
     static QScriptContext *get(QScriptContextPrivate *d) { return d->q_func(); }
@@ -96,15 +223,15 @@ public:
     QScriptEnginePrivate *engine;
     const v8::Arguments *arguments;
     const v8::AccessorInfo *accessorInfo;
-    v8::Persistent<v8::Context> context;
-    QList<v8::Persistent<v8::Context> > scopes;
-    v8::Persistent<v8::Context> inheritedScope;
+    Handle<v8::Context> context;
+    QList<Handle<v8::Context> > scopes;
+    Handle<v8::Context> inheritedScope;
     QScriptContextPrivate *parent; //the parent native frame as seen by the engine
     mutable QScriptContextPrivate *previous; //the previous js frame (lazily build)
-    v8::Persistent<v8::StackFrame> frame; //only for js frames
+    Handle<v8::StackFrame> frame; //only for js frames
     QScriptSharedDataPointer<QScriptValuePrivate> argsObject;
-    v8::Persistent<v8::Object> m_thisObject;
-    v8::Persistent<v8::Value> m_callee;
+    Handle<v8::Object> m_thisObject;
+    Handle<v8::Value> m_callee;
     bool hasArgumentGetter;
 
     static const int stackTraceLimit = 100;
@@ -123,7 +250,7 @@ class QScriptContextPrivate::Stack : public QScriptContextPrivate
 {
 public:
     inline Stack(QScriptEnginePrivate *engine); // the global context (member of QScriptEnginePrivate)
-    inline Stack(QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Handle<v8::Value> callee = v8::Handle<v8::Value>(), v8::Handle<v8::Object> customThisObject = v8::Handle<v8::Object>()); // native function context (on the stack)
+    inline Stack(QScriptEnginePrivate *engine, const v8::Arguments *args, v8::Local<v8::Value> callee = v8::Local<v8::Value>(), v8::Local<v8::Object> customThisObject = v8::Local<v8::Object>()); // native function context (on the stack)
     inline Stack(QScriptEnginePrivate *engine, const v8::AccessorInfo *accessor); // native acessors (on the stack)
     // Only base class is used so destructor here is pointless
 private:
@@ -145,7 +272,6 @@ public:
     // Only base class is used so a destructor here is pointless
 };
 
-
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/script/api/qscriptcontextinfo.cpp b/src/script/api/qscriptcontextinfo.cpp
index ca96ecb..274fa81 100644
--- a/src/script/api/qscriptcontextinfo.cpp
+++ b/src/script/api/qscriptcontextinfo.cpp
@@ -128,7 +128,7 @@ QScriptContextInfoPrivate::QScriptContextInfoPrivate(const QScriptContext *conte
     QScriptIsolate api(context_p->engine, QScriptIsolate::NotNullEngine);
     v8::HandleScope handleScope;
     if (context_p->isJSFrame()) {
-        v8::Handle<v8::StackFrame> frame = context_p->frame;
+        v8::Handle<v8::StackFrame> frame = context_p->frame.v8Handle();
         scriptId = frame->GetScriptId()->NumberValue();
         columnNumber = frame->GetColumn();
         lineNumber = frame->GetLineNumber();