handle memory management of QScriptValuePrivate in engine if possible

Avoid calling malloc() and free() so often. The premise is that
QScriptValue is usually a short-lived type, and only a few QScriptValues
exist at a time, so if we cache privates in the engine, QScriptValues
will be much faster to create and destroy.

Reviewed-by: Olivier Goffart

4 files changed, 61 insertions, 17 deletions

diff --git a/src/script/api/qscriptengine.cpp b/src/script/api/qscriptengine.cpp
index afbe6bb..b4b4f91 100644
--- a/src/script/api/qscriptengine.cpp
+++ b/src/script/api/qscriptengine.cpp
@@ -791,7 +791,7 @@ static QScriptValue __setupPackage__(QScriptContext *ctx, QScriptEngine *eng)
 } // namespace QScript
 
 QScriptEnginePrivate::QScriptEnginePrivate()
-    : registeredScriptValues(0), inEval(false)
+    : registeredScriptValues(0), freeScriptValues(0), inEval(false)
 {
     qMetaTypeId<QScriptValue>();
 
@@ -836,6 +836,11 @@ QScriptEnginePrivate::QScriptEnginePrivate()
 
 QScriptEnginePrivate::~QScriptEnginePrivate()
 {
+    while (freeScriptValues) {
+        QScriptValuePrivate *p = freeScriptValues;
+        freeScriptValues = p->next;
+        qFree(p);
+    }
     while (!ownedAgents.isEmpty())
         delete ownedAgents.takeFirst();
     detachAllRegisteredScriptValues();
@@ -851,7 +856,7 @@ QScriptValue QScriptEnginePrivate::scriptValueFromJSCValue(JSC::JSValue value)
     if (!value)
         return QScriptValue();
 
-    QScriptValuePrivate *p_value = new QScriptValuePrivate();
+    QScriptValuePrivate *p_value = new (this)QScriptValuePrivate();
     p_value->engine = this;
     p_value->initFrom(value);
     return QScriptValuePrivate::toPublic(p_value);
@@ -1362,6 +1367,22 @@ bool QScriptEnginePrivate::scriptDisconnect(JSC::JSValue signal, JSC::JSValue re
 
 #endif
 
+QScriptValuePrivate *QScriptEnginePrivate::allocateScriptValuePrivate(size_t size)
+{
+    if (freeScriptValues) {
+        QScriptValuePrivate *p = freeScriptValues;
+        freeScriptValues = p->next;
+        return p;
+    }
+    return reinterpret_cast<QScriptValuePrivate*>(qMalloc(size));
+}
+
+void QScriptEnginePrivate::freeScriptValuePrivate(QScriptValuePrivate *p)
+{
+    p->next = freeScriptValues;
+    freeScriptValues = p;
+}
+
 void QScriptEnginePrivate::registerScriptValue(QScriptValuePrivate *value)
 {
     value->prev = 0;
diff --git a/src/script/api/qscriptengine_p.h b/src/script/api/qscriptengine_p.h
index eb660e2..1142fcb 100644
--- a/src/script/api/qscriptengine_p.h
+++ b/src/script/api/qscriptengine_p.h
@@ -210,6 +210,9 @@ public:
     bool scriptDisconnect(JSC::JSValue signal, JSC::JSValue receiver,
                           JSC::JSValue function);
 
+    QScriptValuePrivate *allocateScriptValuePrivate(size_t);
+    void freeScriptValuePrivate(QScriptValuePrivate *p);
+
     void registerScriptValue(QScriptValuePrivate *value);
     void unregisterScriptValue(QScriptValuePrivate *value);
     void detachAllRegisteredScriptValues();
@@ -237,6 +240,7 @@ public:
     QScriptEngineAgent *activeAgent;
     int agentLineNumber;
     QScriptValuePrivate *registeredScriptValues;
+    QScriptValuePrivate *freeScriptValues;
     QHash<int, QScriptTypeInfo*> m_typeInfos;
     int processEventsInterval;
     QScriptValue abortResult;
diff --git a/src/script/api/qscriptvalue.cpp b/src/script/api/qscriptvalue.cpp
index a9c07a7..4b92049 100644
--- a/src/script/api/qscriptvalue.cpp
+++ b/src/script/api/qscriptvalue.cpp
@@ -406,6 +406,22 @@ void QScriptValuePrivate::detachFromEngine()
     engine = 0;
 }
 
+void* QScriptValuePrivate::operator new(size_t size, QScriptEnginePrivate *engine)
+{
+    if (engine)
+        return engine->allocateScriptValuePrivate(size);
+    return qMalloc(size);
+}
+
+void QScriptValuePrivate::operator delete(void *ptr)
+{
+    QScriptValuePrivate *d = reinterpret_cast<QScriptValuePrivate*>(ptr);
+    if (d->engine)
+        d->engine->freeScriptValuePrivate(d);
+    else
+        qFree(d);
+}
+
 /*!
   Constructs an invalid QScriptValue.
 */
@@ -440,7 +456,7 @@ QScriptValue::QScriptValue(const QScriptValue &other)
   registers it with the script \a engine.
 */
 QScriptValue::QScriptValue(QScriptEngine *engine, QScriptValue::SpecialValue value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     switch (value) {
@@ -462,7 +478,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, QScriptValue::SpecialValue val
   registers it with the script \a engine.
 */
 QScriptValue::QScriptValue(QScriptEngine *engine, bool val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     d_ptr->initFrom(JSC::jsBoolean(val));
@@ -476,7 +492,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, bool val)
   registers it with the script \a engine.
 */
 QScriptValue::QScriptValue(QScriptEngine *engine, int val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     if (engine) {
@@ -499,7 +515,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, int val)
   registers it with the script \a engine.
  */
 QScriptValue::QScriptValue(QScriptEngine *engine, uint val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     if (engine) {
@@ -522,7 +538,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, uint val)
   registers it with the script \a engine.
 */
 QScriptValue::QScriptValue(QScriptEngine *engine, qsreal val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     if (engine) {
@@ -545,7 +561,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, qsreal val)
   registers it with the script \a engine.
 */
 QScriptValue::QScriptValue(QScriptEngine *engine, const QString &val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     if (engine) {
@@ -566,7 +582,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, const QString &val)
 
 #ifndef QT_NO_CAST_FROM_ASCII
 QScriptValue::QScriptValue(QScriptEngine *engine, const char *val)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (QScriptEnginePrivate::get(engine))QScriptValuePrivate)
 {
     d_ptr->engine = QScriptEnginePrivate::get(engine);
     if (engine) {
@@ -584,7 +600,7 @@ QScriptValue::QScriptValue(QScriptEngine *engine, const char *val)
   Constructs a new QScriptValue with a special \a value.
 */
 QScriptValue::QScriptValue(SpecialValue value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     switch (value) {
@@ -603,7 +619,7 @@ QScriptValue::QScriptValue(SpecialValue value)
   Constructs a new QScriptValue with a boolean \a value.
 */
 QScriptValue::QScriptValue(bool value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     d_ptr->initFrom(JSC::jsBoolean(value));
@@ -615,7 +631,7 @@ QScriptValue::QScriptValue(bool value)
   Constructs a new QScriptValue with a number \a value.
 */
 QScriptValue::QScriptValue(int value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     JSC::JSValue immediate = JSC::JSImmediate::from(value);
@@ -631,7 +647,7 @@ QScriptValue::QScriptValue(int value)
   Constructs a new QScriptValue with a number \a value.
 */
 QScriptValue::QScriptValue(uint value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     JSC::JSValue immediate = JSC::JSImmediate::from(value);
@@ -647,7 +663,7 @@ QScriptValue::QScriptValue(uint value)
   Constructs a new QScriptValue with a number \a value.
 */
 QScriptValue::QScriptValue(qsreal value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     JSC::JSValue immediate = JSC::JSImmediate::from(value);
@@ -663,7 +679,7 @@ QScriptValue::QScriptValue(qsreal value)
   Constructs a new QScriptValue with a string \a value.
 */
 QScriptValue::QScriptValue(const QString &value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     d_ptr->initFrom(value);
@@ -675,7 +691,7 @@ QScriptValue::QScriptValue(const QString &value)
   Constructs a new QScriptValue with a string \a value.
 */
 QScriptValue::QScriptValue(const QLatin1String &value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     d_ptr->initFrom(value);
@@ -689,7 +705,7 @@ QScriptValue::QScriptValue(const QLatin1String &value)
 
 #ifndef QT_NO_CAST_FROM_ASCII
 QScriptValue::QScriptValue(const char *value)
-    : d_ptr(new QScriptValuePrivate)
+    : d_ptr(new (/*engine=*/0)QScriptValuePrivate)
 {
     d_ptr->engine = 0;
     d_ptr->initFrom(QString::fromAscii(value));
diff --git a/src/script/api/qscriptvalue_p.h b/src/script/api/qscriptvalue_p.h
index cb4f1ba..115c755 100644
--- a/src/script/api/qscriptvalue_p.h
+++ b/src/script/api/qscriptvalue_p.h
@@ -68,6 +68,9 @@ class QScriptValuePrivate
 {
     Q_DISABLE_COPY(QScriptValuePrivate);
 public:
+    void* operator new(size_t, QScriptEnginePrivate*);
+    void operator delete(void*);
+
     enum Type {
         JSC,
         Number,