Force write to happen on correct thread

src/comm/LinkInterface.cc

@@ -22,8 +22,10 @@ LinkInterface::LinkInterface(SharedLinkConfigurationPtr& config, bool isPX4Flow)
     , _isPX4Flow(isPX4Flow)
 {
     QQmlEngine::setObjectOwnership(this, QQmlEngine::CppOwnership);
-
     qRegisterMetaType<LinkInterface*>("LinkInterface*");
+
+    // This will cause the writeBytes calls to end up on the thread of the link
+    QObject::connect(this, &LinkInterface::_invokeWriteBytes, this, &LinkInterface::_writeBytes);
 }
 
 LinkInterface::~LinkInterface()
@@ -80,10 +82,7 @@ void LinkInterface::_freeMavlinkChannel()
 
 void LinkInterface::writeBytesThreadSafe(const char *bytes, int length)
 {
-    QByteArray byteArray(bytes, length);
-    _writeBytesMutex.lock();
-    _writeBytes(byteArray);
-    _writeBytesMutex.unlock();
+    emit _invokeWriteBytes(QByteArray(bytes, length));
 }
 
 void LinkInterface::addVehicleReference(void)

src/comm/LinkInterface.h

@@ -76,6 +76,7 @@ signals:
     void connected          (void);
     void disconnected       (void);
     void communicationError (const QString& title, const QString& error);
+    void _invokeWriteBytes  (QByteArray);
 
 protected:
     // Links are only created by LinkManager so constructor is not public
@@ -96,19 +97,18 @@ protected:
     virtual bool _allocateMavlinkChannel();
     virtual void _freeMavlinkChannel    ();
 
+private slots:
+    virtual void _writeBytes(const QByteArray) = 0; // Not thread safe if called directly, only writeBytesThreadSafe is thread safe
+
 private:
     // connect is private since all links should be created through LinkManager::createConnectedLink calls
     virtual bool _connect(void) = 0;
 
-    virtual void _writeBytes(const QByteArray) = 0; // Not thread safe, only writeBytesThreadSafe is thread safe
-
     uint8_t _mavlinkChannel             = std::numeric_limits<uint8_t>::max();
     bool    _decodedFirstMavlinkPacket  = false;
     bool    _isPX4Flow                  = false;
     int     _vehicleReferenceCount      = 0;
 
-    mutable QMutex _writeBytesMutex;
-
     QMap<int /* vehicle id */, MavlinkMessagesTimer*> _mavlinkMessagesTimers;
 };