guard connection addition by a mutex in Socket

libraries/networking/src/udt/SendQueue.cpp

@@ -335,7 +335,11 @@ void SendQueue::run() {
                 // then signal the queue is inactive and return so it can be cleaned up
                 qDebug() << "SendQueue to" << _destination << "reached" << NUM_TIMEOUTS_BEFORE_INACTIVE << "timeouts and is"
                     << "considered inactive. It is now being stopped.";
+                
                 emit queueInactive();
+                
+                _isRunning = false;
+                
                 return;
             } else {
                 // During our processing above we didn't send any packets
@@ -366,6 +370,9 @@ void SendQueue::run() {
                             
                             // this queue is inactive - emit that signal and stop the while
                             emit queueInactive();
+                            
+                            _isRunning = false;
+                            
                             return;
                         }
                     } else {

libraries/networking/src/udt/Socket.cpp

@@ -143,6 +143,8 @@ qint64 Socket::writeDatagram(const QByteArray& datagram, const HifiSockAddr& soc
 }
 
 Connection& Socket::findOrCreateConnection(const HifiSockAddr& sockAddr) {
+    QWriteLocker locker(&_connectionsMutex);
+    
     auto it = _connectionsHash.find(sockAddr);
 
     if (it == _connectionsHash.end()) {
@@ -160,12 +162,16 @@ void Socket::clearConnections() {
         return;
     }
     
+    QWriteLocker locker(&_connectionsMutex);
+    
     // clear all of the current connections in the socket
     qDebug() << "Clearing all remaining connections in Socket.";
     _connectionsHash.clear();
 }
 
 void Socket::cleanupConnection(HifiSockAddr sockAddr) {
+    QWriteLocker locker(&_connectionsMutex);
+    
     qCDebug(networking) << "Socket::cleanupConnection called for UDT connection to" << sockAddr;
     _connectionsHash.erase(sockAddr);
 }

libraries/networking/src/udt/Socket.h

@@ -94,6 +94,8 @@ private:
     std::unordered_map<HifiSockAddr, SequenceNumber> _unreliableSequenceNumbers;
     std::unordered_map<HifiSockAddr, std::unique_ptr<Connection>> _connectionsHash;
     
+    QReadWriteLock _connectionsMutex; // guards concurrent access to connections hashs
+    
     int _synInterval = 10; // 10ms
     QTimer _synTimer;