Multi link support clean up

- Improve function names
- For notifications of an active link change only show the priority keyword if multiple links are connected
- Use QMap instead of QList for the HeartbeatTimers
- Style improvements
- Simplify sending the MAV_CMD_CONTROL_HIGH_LATENCY command

src/Vehicle/Vehicle.cc

@@ -1611,9 +1611,9 @@ void Vehicle::_addLink(LinkInterface* link)
         qCDebug(VehicleLog) << "_addLink:" << QString("%1").arg((ulong)link, 0, 16);
         _links += link;
         if (_links.count() <= 1) {
-            _updatePriorityLink(true, false);
+            _updatePriorityLink(true /* updateActive */, false /* sendCommand */);
         } else {
-            _updatePriorityLink(true, true);
+            _updatePriorityLink(true /* updateActive */, true /* sendCommand */);
         }
 
         connect(_toolbox->linkManager(), &LinkManager::linkInactive, this, &Vehicle::_linkInactiveOrDeleted);
@@ -1633,7 +1633,7 @@ void Vehicle::_linkInactiveOrDeleted(LinkInterface* link)
         _priorityLink.clear();
     }
 
-    _updatePriorityLink(true, true);
+    _updatePriorityLink(true /* updateActive */, true /* sendCommand */);
 
     if (_links.count() == 0 && !_allLinksInactiveSent) {
         qCDebug(VehicleLog) << "All links inactive";
@@ -2480,7 +2480,7 @@ void Vehicle::_linkActiveChanged(LinkInterface *link, bool active, int vehicleID
             // communication to priority link regained
             _connectionLost = false;
             emit connectionLostChanged(false);
-            qgcApp()->showMessage((tr("%1 communication to priority link %2 regained")).arg(_vehicleIdSpeech()).arg(link->getName()));
+            qgcApp()->showMessage((tr("%1 communication to %2 link %3 regained")).arg(_vehicleIdSpeech()).arg((_links.count() > 1) ? "priority" : "").arg(link->getName()));
 
             if (_priorityLink->highLatency()) {
                 _setMaxProtoVersion(100);
@@ -2494,9 +2494,9 @@ void Vehicle::_linkActiveChanged(LinkInterface *link, bool active, int vehicleID
 
         } else if (!active && !_connectionLost) {
             // communication to priority link lost
-            qgcApp()->showMessage((tr("%1 communication to priority link %2 lost")).arg(_vehicleIdSpeech()).arg(link->getName()));
+            qgcApp()->showMessage((tr("%1 communication to %2 link %3 lost")).arg(_vehicleIdSpeech()).arg((_links.count() > 1) ? "priority" : "").arg(link->getName()));
 
-            _updatePriorityLink(false, true);
+            _updatePriorityLink(false /* updateActive */, true /* sendCommand */);
 
             if (link == _priorityLink) {
                 _say(QString(tr("%1 communication lost")).arg(_vehicleIdSpeech()));
@@ -2520,7 +2520,7 @@ void Vehicle::_linkActiveChanged(LinkInterface *link, bool active, int vehicleID
         }
     } else {
         qgcApp()->showMessage((tr("%1 communication to auxiliary link %2 %3")).arg(_vehicleIdSpeech()).arg(link->getName()).arg(active ? "regained" : "lost"));
-        _updatePriorityLink(false, true);
+        _updatePriorityLink(false /* updateActive */, true /* sendCommand */);
     }
 }
 
@@ -3408,17 +3408,10 @@ void Vehicle::_updateHighLatencyLink(bool sendCommand)
         emit highLatencyLinkChanged(_highLatencyLink);
 
         if (sendCommand) {
-            if (_highLatencyLink) {
-                sendMavCommand(defaultComponentId(),
-                               MAV_CMD_CONTROL_HIGH_LATENCY,
-                               true,
-                               1.0f); // request start transmitting over high latency telemetry
-            } else {
             sendMavCommand(defaultComponentId(),
                            MAV_CMD_CONTROL_HIGH_LATENCY,
                            true,
-                               0.0f); // request stop transmitting over high latency telemetry
-            }
+                           _highLatencyLink ? 1.0f : 0.0f); // request start/stop transmitting over high latency telemetry
         }
     }
 }

src/comm/LinkInterface.cc

@@ -12,8 +12,10 @@
 
 bool LinkInterface::active() const
 {
-    for( int i=0; i<_heartbeatTimerList.count(); ++i ) {
-        if (_heartbeatTimerList[i]->getActive()) {
+    QMapIterator<int /* vehicle id */, HeartbeatTimer*> iter(_heartbeatTimers);
+    while (iter.hasNext()) {
+        iter.next();
+        if (iter.value()->getActive()) {
             return true;
         }
     }
@@ -23,13 +25,11 @@ bool LinkInterface::active() const
 
 bool LinkInterface::active(int vehicle_id) const
 {
-    for( int i=0; i<_heartbeatTimerList.count(); ++i ) {
-        if (_heartbeatTimerList[i]->getVehicleID() == vehicle_id) {
-            return _heartbeatTimerList[i]->getActive();
-        }
-    }
-
+    if (_heartbeatTimers.contains(vehicle_id)) {
+        return _heartbeatTimers.value(vehicle_id)->getActive();
+    } else {
         return false;
+    }
 }
 
 /// mavlink channel to use for this link, as used by mavlink_parse_char. The mavlink channel is only
@@ -186,29 +186,23 @@ void LinkInterface::_activeChanged(bool active, int vehicle_id)
     emit activeChanged(this, active, vehicle_id);
 }
 
-void LinkInterface::timerStart(int vehicle_id) {
-    int timer_index{-1};
-    for( int i=0; i<_heartbeatTimerList.count(); ++i ) {
-        if (_heartbeatTimerList[i]->getVehicleID() == vehicle_id) {
-            timer_index = i;
-            break;
-        }
-    }
-
-    if (timer_index != -1) {
-        _heartbeatTimerList[timer_index]->restartTimer();
+void LinkInterface::startHeartbeatTimer(int vehicle_id) {
+    if (_heartbeatTimers.contains(vehicle_id)) {
+        _heartbeatTimers.value(vehicle_id)->restartTimer();
     } else {
-        _heartbeatTimerList.append(new HeartbeatTimer(vehicle_id, _highLatency));
-        QObject::connect(_heartbeatTimerList.last(), &HeartbeatTimer::activeChanged, this, &LinkInterface::_activeChanged);
+        _heartbeatTimers.insert(vehicle_id, new HeartbeatTimer(vehicle_id, _highLatency));
+        QObject::connect(_heartbeatTimers.value(vehicle_id), &HeartbeatTimer::activeChanged, this, &LinkInterface::_activeChanged);
     }
 }
 
-void LinkInterface::timerStop() {
-    for(int i=0; i<_heartbeatTimerList.count(); ++i ) {
-        QObject::disconnect(_heartbeatTimerList[i], &HeartbeatTimer::activeChanged, this, &LinkInterface::_activeChanged);
-        delete _heartbeatTimerList[i];
-        _heartbeatTimerList[i] = nullptr;
+void LinkInterface::stopHeartbeatTimer() {
+    QMapIterator<int /* vehicle id */, HeartbeatTimer*> iter(_heartbeatTimers);
+    while (iter.hasNext()) {
+        iter.next();
+        QObject::disconnect(iter.value(), &HeartbeatTimer::activeChanged, this, &LinkInterface::_activeChanged);
+        delete _heartbeatTimers[iter.key()];
+        _heartbeatTimers[iter.key()] = nullptr;
     }
 
-    _heartbeatTimerList.clear();
+    _heartbeatTimers.clear();
 }

src/comm/LinkInterface.h

@@ -39,7 +39,7 @@ class LinkInterface : public QThread
 
 public:    
     virtual ~LinkInterface() {
-        timerStop();
+        stopHeartbeatTimer();
         _config->setLink(NULL);
     }
 
@@ -260,18 +260,19 @@ private:
     void _setMavlinkChannel(uint8_t channel);
     
     /**
-     * @brief timerStart
+     * @brief startHeartbeatTimer
      *
-     * Allocate the timer if it does not exist yet and start it.
+     * Start/restart the heartbeat timer for the specific vehicle.
+     * If no timer exists an instance is allocated.
      */
-    void timerStart(int vehicle_id);
+    void startHeartbeatTimer(int vehicle_id);
 
     /**
-     * @brief timerStop
+     * @brief stopHeartbeatTimer
      *
-     * Stop and deallocate the timer if it exists.
+     * Stop and deallocate the heartbeat timers for all vehicles if any exists.
      */
-    void timerStop();
+    void stopHeartbeatTimer();
 
     bool _mavlinkChannelSet;    ///< true: _mavlinkChannel has been set
     uint8_t _mavlinkChannel;    ///< mavlink channel to use for this link, as used by mavlink_parse_char
@@ -297,7 +298,7 @@ private:
     bool _enableRateCollection;
     bool _decodedFirstMavlinkPacket;    ///< true: link has correctly decoded it's first mavlink packet
 
-    QList<HeartbeatTimer*> _heartbeatTimerList;
+    QMap<int /* vehicle id */, HeartbeatTimer*> _heartbeatTimers;
 };
 
 typedef QSharedPointer<LinkInterface> SharedLinkInterfacePointer;

src/comm/LinkManager.cc

@@ -1011,5 +1011,5 @@ void LinkManager::_heartbeatReceived(LinkInterface* link, int vehicleId, int com
     Q_UNUSED(vehicleFirmwareType);
     Q_UNUSED(vehicleType);
 
-    link->timerStart(vehicleId);
+    link->startHeartbeatTimer(vehicleId);
 }

src/ui/toolbar/LinkIndicator.qml

@@ -59,10 +59,12 @@ Item {
             }
         }
         Component.onCompleted: priorityLinkSelector.updatelinkSelectionMenu()
+
         Connections {
             target:                 QGroundControl.multiVehicleManager
             onActiveVehicleChanged: priorityLinkSelector.updatelinkSelectionMenu()
         }
+
         Connections {
             target:                 _activeVehicle
             onLinkNamesChanged:     priorityLinkSelector.updatelinkSelectionMenu()