From 132eccca92a90e4d67ba8b5a4052384a2b2cfdf9 Mon Sep 17 00:00:00 2001
From: Kent Hansen <kent.hansen@nokia.com>
Date: Mon, 30 Nov 2009 14:15:50 +0100
Subject: Fix garbage collection issue with script-owned objects with
 connections

This reinstates the pre-4.6 behavior: A script-owned C++ object
that's not referenced anymore should be garbage collected, even
if it has connections. In order to achieve this, the "weak"
reference to the C++ object's wrapper must be invalidated.

Task-number: QTBUG-6366
Reviewed-by: Simon Hausmann
---
 src/script/api/qscriptengine.cpp               | 21 ++++++++++----------
 src/script/bridge/qscriptqobject.cpp           | 27 +++++++++++++-------------
 tests/auto/qscriptengine/tst_qscriptengine.cpp | 18 +++++++++++++++++
 3 files changed, 43 insertions(+), 23 deletions(-)

diff --git a/src/script/api/qscriptengine.cpp b/src/script/api/qscriptengine.cpp
index dc0e0d0..b6aa872 100644
--- a/src/script/api/qscriptengine.cpp
+++ b/src/script/api/qscriptengine.cpp
@@ -1101,16 +1101,6 @@ void QScriptEnginePrivate::mark(JSC::MarkStack& markStack)
         }
     }
 
-#ifndef QT_NO_QOBJECT
-    {
-        QHash<QObject*, QScript::QObjectData*>::const_iterator it;
-        for (it = m_qobjectData.constBegin(); it != m_qobjectData.constEnd(); ++it) {
-            QScript::QObjectData *qdata = it.value();
-            qdata->mark(markStack);
-        }
-    }
-#endif
-
     {
         QHash<int, QScriptTypeInfo*>::const_iterator it;
         for (it = m_typeInfos.constBegin(); it != m_typeInfos.constEnd(); ++it) {
@@ -1134,6 +1124,17 @@ void QScriptEnginePrivate::mark(JSC::MarkStack& markStack)
             context = context->parentContext();
         }
     }
+
+#ifndef QT_NO_QOBJECT
+    markStack.drain(); // make sure everything is marked before marking qobject data
+    {
+        QHash<QObject*, QScript::QObjectData*>::const_iterator it;
+        for (it = m_qobjectData.constBegin(); it != m_qobjectData.constEnd(); ++it) {
+            QScript::QObjectData *qdata = it.value();
+            qdata->mark(markStack);
+        }
+    }
+#endif
 }
 
 bool QScriptEnginePrivate::isCollecting() const
diff --git a/src/script/bridge/qscriptqobject.cpp b/src/script/bridge/qscriptqobject.cpp
index 559fcd3..63ba9ec 100644
--- a/src/script/bridge/qscriptqobject.cpp
+++ b/src/script/bridge/qscriptqobject.cpp
@@ -83,22 +83,23 @@ struct QObjectConnection
 
     void mark(JSC::MarkStack& markStack)
     {
-        // ### need to find out if senderWrapper is marked
         if (senderWrapper) {
-            // see if the sender should be marked or not
+            // see if the sender should be marked or not;
+            // if the C++ object is owned by script, we don't want
+            // it to stay alive due to a script connection.
             Q_ASSERT(senderWrapper.inherits(&QScriptObject::info));
             QScriptObject *scriptObject = static_cast<QScriptObject*>(JSC::asObject(senderWrapper));
-            QScriptObjectDelegate *delegate = scriptObject->delegate();
-            Q_ASSERT(delegate && (delegate->type() == QScriptObjectDelegate::QtObject));
-            QObjectDelegate *inst = static_cast<QObjectDelegate*>(delegate);
-            if ((inst->ownership() == QScriptEngine::ScriptOwnership)
-                || ((inst->ownership() == QScriptEngine::AutoOwnership)
-                    && inst->value() && !inst->value()->parent())) {
-                // #### don't mark if not marked otherwise
-                //senderWrapper = JSC::JSValue();
-                markStack.append(senderWrapper);
-            } else {
-                markStack.append(senderWrapper);
+            if (!JSC::Heap::isCellMarked(scriptObject)) {
+                QScriptObjectDelegate *delegate = scriptObject->delegate();
+                Q_ASSERT(delegate && (delegate->type() == QScriptObjectDelegate::QtObject));
+                QObjectDelegate *inst = static_cast<QObjectDelegate*>(delegate);
+                if ((inst->ownership() == QScriptEngine::ScriptOwnership)
+                    || ((inst->ownership() == QScriptEngine::AutoOwnership)
+                        && inst->value() && !inst->value()->parent())) {
+                    senderWrapper = JSC::JSValue();
+                } else {
+                    markStack.append(senderWrapper);
+                }
             }
         }
         if (receiver)
diff --git a/tests/auto/qscriptengine/tst_qscriptengine.cpp b/tests/auto/qscriptengine/tst_qscriptengine.cpp
index 3bc2443..2d629b7 100644
--- a/tests/auto/qscriptengine/tst_qscriptengine.cpp
+++ b/tests/auto/qscriptengine/tst_qscriptengine.cpp
@@ -154,6 +154,7 @@ private slots:
     void functionScopes();
     void nativeFunctionScopes();
     void evaluateProgram();
+    void collectGarbageAfterConnect();
 
     void qRegExpInport_data();
     void qRegExpInport();
@@ -4443,6 +4444,23 @@ void tst_QScriptEngine::evaluateProgram()
     }
 }
 
+void tst_QScriptEngine::collectGarbageAfterConnect()
+{
+    // QTBUG-6366
+    QScriptEngine engine;
+    QPointer<QWidget> widget = new QWidget;
+    engine.globalObject().setProperty(
+        "widget", engine.newQObject(widget, QScriptEngine::ScriptOwnership));
+    QVERIFY(engine.evaluate("widget.customContextMenuRequested.connect(\n"
+                            "  function() { print('hello'); }\n"
+                            ");")
+            .isUndefined());
+    QVERIFY(widget != 0);
+    engine.evaluate("widget = null;");
+    collectGarbage_helper(engine);
+    QVERIFY(widget == 0);
+}
+
 static QRegExp minimal(QRegExp r) { r.setMinimal(true); return r; }
 
 void tst_QScriptEngine::qRegExpInport_data()
-- 
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