Add a way to reset GSDK in cppsdk

cpp/cppsdk/gsdk.cpp

@@ -141,7 +141,10 @@ namespace Microsoft
             GSDKInternal::~GSDKInternal()
             {
                 m_keepHeartbeatRunning = false;
-                m_heartbeatThread.join();
+                if (m_heartbeatThread.joinable())
+                {
+                    m_heartbeatThread.join();
+                }
             }
 
 			//Do not need to acquire lock for configuration becase startLog is only called from the constructor.
@@ -510,6 +513,18 @@ namespace Microsoft
                 GSDKInternal::get();
             }
 
+            void GSDK::reset()
+            {
+                GSDKInternal::get().m_keepHeartbeatRunning = false;
+
+                if (GSDKInternal::get().m_heartbeatThread.joinable())
+                {
+                    GSDKInternal::get().m_heartbeatThread.join();
+                }
+
+                GSDKInternal::m_instance.reset();
+            }
+
             bool GSDK::readyForPlayers()
             {
                 if (GSDKInternal::get().m_heartbeatRequest.m_currentGameState != GameState::Active)

cpp/cppsdk/gsdk.h

@@ -131,6 +131,9 @@ namespace Microsoft
                 /// <param name="debugLogs">Enables outputting additional logs to the GSDK log file.</param>
                 static void start(bool debugLogs = false);
 
+                /// <summary>Resets the GSDK state, joining all threads, requires start to be called before use again</summary>
+                static void reset();
+
                 /// <summary>Tells the Xcloud service information on who is connected.</summary>
                 /// <param name="currentlyConnectedPlayers"></param>
                 static void updateConnectedPlayers(const std::vector<ConnectedPlayer> &currentlyConnectedPlayers);