Debugger: Make sure stateChanged is called from debugger thread

Make sure stateAboutToBeChanged(), stateChanged() is always called
from the debugger thread. This matches how messageReceived()
is called. On exit, run an event loop until all stateAboutToBeChanged
calls have returned.

Change-Id: I9cd6199cc80552ad97e4b7d504ea91aa116a6a34
Reviewed-by: Aurindam Jana <aurindam.jana@nokia.com>

1 files changed, 59 insertions, 18 deletions

diff --git a/src/qml/debugger/qqmldebugserver.cpp b/src/qml/debugger/qqmldebugserver.cpp
index 468b653a1f..3b18f75370 100644
--- a/src/qml/debugger/qqmldebugserver.cpp
+++ b/src/qml/debugger/qqmldebugserver.cpp
@@ -45,6 +45,7 @@
 #include <private/qqmlengine_p.h>
 #include <private/qqmlglobal_p.h>
 
+#include <QtCore/QAtomicInt>
 #include <QtCore/QDir>
 #include <QtCore/QPluginLoader>
 #include <QtCore/QStringList>
@@ -104,9 +105,12 @@ public:
     QStringList waitingForMessageNames;
     QQmlDebugServerThread *thread;
     QPluginLoader loader;
+    QAtomicInt changeServiceStateCalls;
 
 private:
-    // private slot
+    // private slots
+    void _q_changeServiceState(const QString &serviceName,
+                               QQmlDebugService::State newState);
     void _q_sendMessages(const QList<QByteArray> &messages);
 };
 
@@ -139,6 +143,8 @@ QQmlDebugServerPrivate::QQmlDebugServerPrivate() :
 {
     // used in _q_sendMessages
     qRegisterMetaType<QList<QByteArray> >("QList<QByteArray>");
+    // used in _q_changeServiceState
+    qRegisterMetaType<QQmlDebugService::State>("QQmlDebugService::State");
 }
 
 void QQmlDebugServerPrivate::advertisePlugins()
@@ -332,6 +338,7 @@ QQmlDebugServer::QQmlDebugServer()
     qAddPostRoutine(cleanup);
 }
 
+// called from GUI thread!
 QQmlDebugServer::~QQmlDebugServer()
 {
     Q_D(QQmlDebugServer);
@@ -339,13 +346,20 @@ QQmlDebugServer::~QQmlDebugServer()
     QReadLocker(&d->pluginsLock);
     {
         foreach (QQmlDebugService *service, d->plugins.values()) {
-            service->stateAboutToBeChanged(QQmlDebugService::NotConnected);
-            service->d_func()->server = 0;
-            service->d_func()->state = QQmlDebugService::NotConnected;
-            service->stateChanged(QQmlDebugService::NotConnected);
+            d->changeServiceStateCalls.ref();
+            QMetaObject::invokeMethod(this, "_q_changeServiceState", Qt::QueuedConnection,
+                                      Q_ARG(QString, service->name()),
+                                      Q_ARG(QQmlDebugService::State, QQmlDebugService::NotConnected));
         }
     }
 
+    // Wait for changeServiceState calls to finish
+    // (while running an event loop because some services
+    // might again use slots to execute stuff in the GUI thread)
+    QEventLoop loop;
+    while (!d->changeServiceStateCalls.testAndSetOrdered(0, 0))
+        loop.processEvents();
+
     if (d->thread) {
         d->thread->exit();
         d->thread->wait();
@@ -394,8 +408,8 @@ void QQmlDebugServer::receiveMessage(const QByteArray &message)
                 QQmlDebugService::State newState = QQmlDebugService::Unavailable;
                 if (d->clientPlugins.contains(iter.key()))
                     newState = QQmlDebugService::Enabled;
-                iter.value()->d_func()->state = newState;
-                iter.value()->stateChanged(newState);
+                d->changeServiceStateCalls.ref();
+                d->_q_changeServiceState(iter.value()->name(), newState);
             }
 
             d->messageArrivedCondition.wakeAll();
@@ -416,8 +430,8 @@ void QQmlDebugServer::receiveMessage(const QByteArray &message)
 
                 if (oldClientPlugins.contains(pluginName)
                         != d->clientPlugins.contains(pluginName)) {
-                    iter.value()->d_func()->state = newState;
-                    iter.value()->stateChanged(newState);
+                    d->changeServiceStateCalls.ref();
+                    d->_q_changeServiceState(iter.value()->name(), newState);
                 }
             }
 
@@ -449,8 +463,34 @@ void QQmlDebugServer::receiveMessage(const QByteArray &message)
     }
 }
 
+void QQmlDebugServerPrivate::_q_changeServiceState(const QString &serviceName,
+                                                   QQmlDebugService::State newState)
+{
+    // to be executed in debugger thread
+    Q_ASSERT(QThread::currentThread() == q_func()->thread());
+
+    QQmlDebugService *service = 0;
+    {
+        QReadLocker lock(&pluginsLock);
+        service = plugins.value(serviceName);
+    }
+
+    if (service && (service->d_func()->state != newState)) {
+        service->stateAboutToBeChanged(newState);
+        service->d_func()->state = newState;
+        if (newState == QQmlDebugService::NotConnected)
+            service->d_func()->server = 0;
+        service->stateChanged(newState);
+    }
+
+    changeServiceStateCalls.deref();
+}
+
 void QQmlDebugServerPrivate::_q_sendMessages(const QList<QByteArray> &messages)
 {
+    // to be executed in debugger thread
+    Q_ASSERT(QThread::currentThread() == q_func()->thread());
+
     if (connection)
         connection->send(messages);
 }
@@ -494,18 +534,18 @@ bool QQmlDebugServer::removeService(QQmlDebugService *service)
     Q_D(QQmlDebugServer);
     {
         QWriteLocker(&d->pluginsLock);
+        QQmlDebugService::State newState = QQmlDebugService::NotConnected;
+
+        d->changeServiceStateCalls.ref();
+        QMetaObject::invokeMethod(this, "_q_changeServiceState", Qt::QueuedConnection,
+                                  Q_ARG(QString, service->name()),
+                                  Q_ARG(QQmlDebugService::State, newState));
+
         if (!service || !d->plugins.contains(service->name()))
             return false;
         d->plugins.remove(service->name());
-    }
-    {
-        QReadLocker(&d->pluginsLock);
-        QQmlDebugService::State newState = QQmlDebugService::NotConnected;
-        service->stateAboutToBeChanged(newState);
+
         d->advertisePlugins();
-        service->d_func()->server = 0;
-        service->d_func()->state = newState;
-        service->stateChanged(newState);
     }
 
     return true;
@@ -522,7 +562,8 @@ void QQmlDebugServer::sendMessages(QQmlDebugService *service,
         prefixedMessages << prefixed;
     }
 
-    QMetaObject::invokeMethod(this, "_q_sendMessages", Qt::QueuedConnection, Q_ARG(QList<QByteArray>, prefixedMessages));
+    QMetaObject::invokeMethod(this, "_q_sendMessages", Qt::QueuedConnection,
+                              Q_ARG(QList<QByteArray>, prefixedMessages));
 }
 
 bool QQmlDebugServer::waitForMessage(QQmlDebugService *service)