Unload script on end execution and error

A ScriptEngineAgent is added to monitor the execution of a
script. If it ends it stops the script to free resources.

The same is done in case of an exception, just that in this
case the script takes care of unloading itself.

REVIEW: 104871

scripting/scripting.cpp

@@ -157,6 +157,7 @@ KWin::Script::Script(int id, QString scriptName, QString pluginName, QObject* pa
     : AbstractScript(id, scriptName, pluginName, parent)
     , m_engine(new QScriptEngine(this))
     , m_starting(false)
+    , m_agent(new ScriptUnloaderAgent(this))
 {
     QDBusConnection::sessionBus().registerObject('/' + QString::number(scriptId()), this, QDBusConnection::ExportScriptableContents | QDBusConnection::ExportScriptableInvokables);
 }
@@ -235,6 +236,19 @@ void KWin::Script::sigException(const QScriptValue& exception)
         }
     }
     emit printError(exception.toString());
+    stop();
+}
+
+KWin::ScriptUnloaderAgent::ScriptUnloaderAgent(KWin::Script *script)
+    : QScriptEngineAgent(script->engine())
+    , m_script(script)
+{
+    script->engine()->setAgent(this);
+}
+
+void KWin::ScriptUnloaderAgent::scriptUnload(qint64 id)
+{
+    m_script->stop();
 }
 
 KWin::DeclarativeScript::DeclarativeScript(int id, QString scriptName, QString pluginName, QObject* parent)

scripting/scripting.h

@@ -25,6 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QtCore/QFile>
 #include <QtCore/QHash>
 #include <QtCore/QStringList>
+#include <QtScript/QScriptEngineAgent>
 
 class QAction;
 class QDeclarativeView;
@@ -38,6 +39,7 @@ typedef QList< QPair<bool, QPair<QString, QString > > > LoadScriptList;
 
 namespace KWin
 {
+class ScriptUnloaderAgent;
 class WorkspaceWrapper;
 
 class AbstractScript : public QObject
@@ -108,6 +110,9 @@ public:
 
     Script(int id, QString scriptName, QString pluginName, QObject *parent = NULL);
     virtual ~Script();
+    QScriptEngine *engine() {
+        return m_engine;
+    }
 
 public Q_SLOTS:
     Q_SCRIPTABLE void run();
@@ -134,6 +139,17 @@ private:
     QByteArray loadScriptFromFile();
     QScriptEngine *m_engine;
     bool m_starting;
+    QScopedPointer<ScriptUnloaderAgent> m_agent;
+};
+
+class ScriptUnloaderAgent : public QScriptEngineAgent
+{
+public:
+    ScriptUnloaderAgent(Script *script);
+    virtual void scriptUnload(qint64 id);
+
+private:
+    Script *m_script;
 };
 
 class DeclarativeScript : public AbstractScript