QmlDebug: Don't lie about blocked engines in EngineControl

Previously additional engineIds could be accidentally added to the list
by processing the engineAdded and engineRemoved signals.

Change-Id: Ibac0c1ff48ae31c736371d319fe91d33a3396b05
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 25 insertions, 13 deletions

diff --git a/src/qmldebug/qqmlenginecontrolclient.cpp b/src/qmldebug/qqmlenginecontrolclient.cpp
index 3f75298e51..13f216ce38 100644
--- a/src/qmldebug/qqmlenginecontrolclient.cpp
+++ b/src/qmldebug/qqmlenginecontrolclient.cpp
@@ -108,32 +108,37 @@ void QQmlEngineControlClient::messageReceived(const QByteArray &data)
     if (!stream.atEnd())
         stream >> name;
 
-    QQmlEngineControlClientPrivate::EngineState &state = d->blockedEngines[id];
-    Q_ASSERT(state.blockers == 0);
-    Q_ASSERT(state.releaseCommand == QQmlEngineControlClientPrivate::InvalidCommand);
+    auto handleWaiting = [&](
+            QQmlEngineControlClientPrivate::CommandType command, std::function<void()> emitter) {
+        QQmlEngineControlClientPrivate::EngineState &state = d->blockedEngines[id];
+        Q_ASSERT(state.blockers == 0);
+        Q_ASSERT(state.releaseCommand == QQmlEngineControlClientPrivate::InvalidCommand);
+        state.releaseCommand = command;
+        emitter();
+        if (state.blockers == 0) {
+            d->sendCommand(state.releaseCommand, id);
+            d->blockedEngines.remove(id);
+        }
+    };
 
     switch (message) {
     case QQmlEngineControlClientPrivate::EngineAboutToBeAdded:
-        state.releaseCommand = QQmlEngineControlClientPrivate::StartWaitingEngine;
-        emit engineAboutToBeAdded(id, name);
+        handleWaiting(QQmlEngineControlClientPrivate::StartWaitingEngine, [&](){
+            emit engineAboutToBeAdded(id, name);
+        });
         break;
     case QQmlEngineControlClientPrivate::EngineAdded:
         emit engineAdded(id, name);
         break;
     case QQmlEngineControlClientPrivate::EngineAboutToBeRemoved:
-        state.releaseCommand = QQmlEngineControlClientPrivate::StopWaitingEngine;
-        emit engineAboutToBeRemoved(id, name);
+        handleWaiting(QQmlEngineControlClientPrivate::StopWaitingEngine, [&](){
+            emit engineAboutToBeRemoved(id, name);
+        });
         break;
     case QQmlEngineControlClientPrivate::EngineRemoved:
         emit engineRemoved(id, name);
         break;
     }
-
-    if (state.blockers == 0 &&
-            state.releaseCommand != QQmlEngineControlClientPrivate::InvalidCommand) {
-        d->sendCommand(state.releaseCommand, id);
-        d->blockedEngines.remove(id);
-    }
 }
 
 QQmlEngineControlClientPrivate::QQmlEngineControlClientPrivate(QQmlDebugConnection *connection) :
diff --git a/tests/auto/qml/debugger/qqmlenginecontrol/tst_qqmlenginecontrol.cpp b/tests/auto/qml/debugger/qqmlenginecontrol/tst_qqmlenginecontrol.cpp
index 18ba133876..a8c43b1c75 100644
--- a/tests/auto/qml/debugger/qqmlenginecontrol/tst_qqmlenginecontrol.cpp
+++ b/tests/auto/qml/debugger/qqmlenginecontrol/tst_qqmlenginecontrol.cpp
@@ -113,9 +113,12 @@ void tst_QQmlEngineControl::startEngine()
 
     QTRY_VERIFY(!m_client->blockedEngines().empty());
     m_client->releaseEngine(m_client->blockedEngines().last());
+    QVERIFY(m_client->blockedEngines().isEmpty());
 
     QVERIFY2(QQmlDebugTest::waitForSignal(m_client, SIGNAL(engineAdded(int,QString))),
              "No engine start message received in time.");
+
+    QVERIFY(m_client->blockedEngines().isEmpty());
 }
 
 void tst_QQmlEngineControl::stopEngine_data()
@@ -131,15 +134,19 @@ void tst_QQmlEngineControl::stopEngine()
 
     QTRY_VERIFY(!m_client->blockedEngines().empty());
     m_client->releaseEngine(m_client->blockedEngines().last());
+    QVERIFY(m_client->blockedEngines().isEmpty());
 
     QVERIFY2(QQmlDebugTest::waitForSignal(m_client, SIGNAL(engineAdded(int,QString))),
              "No engine start message received in time.");
+    QVERIFY(m_client->blockedEngines().isEmpty());
 
     QVERIFY2(QQmlDebugTest::waitForSignal(m_client, SIGNAL(engineAboutToBeRemoved(int,QString))),
              "No engine about to stop message received in time.");
     m_client->releaseEngine(m_client->blockedEngines().last());
+    QVERIFY(m_client->blockedEngines().isEmpty());
     QVERIFY2(QQmlDebugTest::waitForSignal(m_client, SIGNAL(engineRemoved(int,QString))),
              "No engine stop message received in time.");
+    QVERIFY(m_client->blockedEngines().isEmpty());
 }
 
 QTEST_MAIN(tst_QQmlEngineControl)