Enforce threadsafe shutdown and deletion of MAVLinkDecoder

src/ui/MAVLinkDecoder.cc

@@ -3,10 +3,9 @@
 
 #include <QDebug>
 
-MAVLinkDecoder::MAVLinkDecoder(MAVLinkProtocol* protocol, QObject *parent) :
-    QThread()
+MAVLinkDecoder::MAVLinkDecoder(MAVLinkProtocol* protocol) :
+    QThread(), creationThread(QThread::currentThread())
 {
-    Q_UNUSED(parent);
     // We're doing it wrong - because the Qt folks got the API wrong:
     // http://blog.qt.digia.com/blog/2010/06/17/youre-doing-it-wrong/
     moveToThread(this);
@@ -52,6 +51,7 @@ MAVLinkDecoder::MAVLinkDecoder(MAVLinkProtocol* protocol, QObject *parent) :
 //    textMessageFilter.insert(MAVLINK_MSG_ID_HIGHRES_IMU, false);
 
     connect(protocol, &MAVLinkProtocol::messageReceived, this, &MAVLinkDecoder::receiveMessage);
+    connect(this, &MAVLinkDecoder::finish, this, &QThread::quit);
 
     start(LowPriority);
 }
@@ -63,6 +63,7 @@ MAVLinkDecoder::MAVLinkDecoder(MAVLinkProtocol* protocol, QObject *parent) :
 void MAVLinkDecoder::run()
 {
     exec();
+    moveToThread(creationThread);
 }
 
 void MAVLinkDecoder::receiveMessage(LinkInterface* link,mavlink_message_t message)

src/ui/MAVLinkDecoder.h

@@ -8,13 +8,14 @@ class MAVLinkDecoder : public QThread
 {
     Q_OBJECT
 public:
-    MAVLinkDecoder(MAVLinkProtocol* protocol, QObject *parent = 0);
+    MAVLinkDecoder(MAVLinkProtocol* protocol);
 
     void run();
 
 signals:
     void textMessageReceived(int uasid, int componentid, int severity, const QString& text);
     void valueChanged(const int uasId, const QString& name, const QString& unit, const QVariant& value, const quint64 msec);
+    void finish(); ///< Trigger a thread safe shutdown
 
 public slots:
     /** @brief Receive one message from the protocol and decode it */
@@ -35,6 +36,7 @@ protected:
     quint64 onboardTimeOffset[cMessageIds];                 ///< Offset of onboard time from Unix epoch (of the receiving GCS)
     qint64 onboardToGCSUnixTimeOffsetAndDelay[cMessageIds]; ///< Offset of onboard time and GCS Unix time
     quint64 firstOnboardTime[cMessageIds];                  ///< First seen onboard time
+    QThread* creationThread;                                ///< QThread on which the object is created
 };
 
 #endif // MAVLINKDECODER_H

src/ui/MainWindow.cc

@@ -274,6 +274,11 @@ MainWindow::MainWindow()
 
 MainWindow::~MainWindow()
 {
+    // Enforce thread-safe shutdown of the mavlink decoder
+    mavlinkDecoder->finish();
+    mavlinkDecoder->wait(1000);
+    mavlinkDecoder->deleteLater();
+
     // This needs to happen before we get into the QWidget dtor
     // otherwise  the QML engine reads freed data and tries to
     // destroy MainWindow a second time.
@@ -290,8 +295,7 @@ QString MainWindow::_getWindowGeometryKey()
 void MainWindow::_buildCommonWidgets(void)
 {
     // Add generic MAVLink decoder
-    // TODO: This is never deleted
-    mavlinkDecoder = new MAVLinkDecoder(qgcApp()->toolbox()->mavlinkProtocol(), this);
+    mavlinkDecoder = new MAVLinkDecoder(qgcApp()->toolbox()->mavlinkProtocol());
     connect(mavlinkDecoder.data(), &MAVLinkDecoder::valueChanged, this, &MainWindow::valueChanged);
 
     // Log player