Prevent hangs in networking game if system clock running backwards

Benau · Benau · commit e2b694f47fca · 2019-04-16T19:16:55.000+08:00
diff --git a/src/main_loop.cpp b/src/main_loop.cpp
@@ -33,6 +33,7 @@
 #include "modes/profile_world.hpp"
 #include "modes/world.hpp"
 #include "network/network_config.hpp"
+#include "network/network_timer_synchronizer.hpp"
 #include "network/protocols/game_protocol.hpp"
 #include "network/protocol_manager.hpp"
 #include "network/race_event_manager.hpp"
@@ -118,6 +119,31 @@ float MainLoop::getLimitedDt()
     while( 1 )
     {
         m_curr_time = StkTime::getRealTimeMs();
+        if (m_prev_time > m_curr_time)
+        {
+            m_prev_time = m_curr_time;
+            // If system time adjusted backwards, return fixed dt and
+            // resynchronize network timer if exists in client
+            if (STKHost::existHost())
+            {
+#ifndef SERVER_ONLY
+                if (UserConfigParams::m_artist_debug_mode &&
+                    !ProfileWorld::isNoGraphics())
+                {
+                    core::stringw err = L"System clock running backwards in"
+                        " networking game.";
+                    MessageQueue::add(MessageQueue::MT_ERROR, err);
+                }
+#endif
+                Log::error("MainLoop", "System clock running backwards in"
+                    " networking game.");
+                if (STKHost::get()->getNetworkTimerSynchronizer())
+                {
+                    STKHost::get()->getNetworkTimerSynchronizer()
+                        ->resynchroniseTimer();
+                }
+            }
+        }
         dt = (float)(m_curr_time - m_prev_time);
         // On a server (i.e. without graphics) the frame rate can be under
         // 1 ms, i.e. dt = 0. Additionally, the resolution of a sleep
@@ -128,12 +154,15 @@ float MainLoop::getLimitedDt()
         // with clients (server time is supposed to be behind client time).
         // So we play it safe by adding a loop to make sure at least 1ms
         // (minimum time that can be handled by the integer timer) delay here.
-        // Only exception is profile mode (typically running without graphics),
-        // which we want to run as fast as possible.
-        while (dt <= 0 && !ProfileWorld::isProfileMode())
+        while (dt == 0)
         {
             StkTime::sleep(1);
             m_curr_time = StkTime::getRealTimeMs();
+            if (m_prev_time > m_curr_time)
+            {
+                Log::error("MainLopp", "System clock keeps backwards!");
+                m_prev_time = m_curr_time;
+            }
             dt = (float)(m_curr_time - m_prev_time);
         }
 
diff --git a/src/network/network_timer_synchronizer.hpp b/src/network/network_timer_synchronizer.hpp
@@ -53,6 +53,8 @@ class NetworkTimerSynchronizer
         m_force_set_timer.store(true);
     }
     // ------------------------------------------------------------------------
+    void resynchroniseTimer()                  { m_synchronised.store(false); }
+    // ------------------------------------------------------------------------
     void addAndSetTime(uint32_t ping, uint64_t server_time)
     {
         if (m_synchronised.load() == true)
@@ -94,6 +96,7 @@ class NetworkTimerSynchronizer
                 UserConfigParams::m_timer_sync_difference_tolerance)
             {
                 STKHost::get()->setNetworkTimer(averaged_time);
+                m_times.clear();
                 m_force_set_timer.store(false);
                 m_synchronised.store(true);
                 Log::info("NetworkTimerSynchronizer", "Network "

Original file line number	Diff line number	Diff line change
`@@ -53,6 +53,8 @@ class NetworkTimerSynchronizer`
`53`	`53`	`m_force_set_timer.store(true);`
`54`	`54`	`}`
`55`	`55`	`// ------------------------------------------------------------------------`
	`56`	`+ void resynchroniseTimer() { m_synchronised.store(false); }`
	`57`	`+ // ------------------------------------------------------------------------`
`56`	`58`	`void addAndSetTime(uint32_t ping, uint64_t server_time)`
`57`	`59`	`{`
`58`	`60`	`if (m_synchronised.load() == true)`
`@@ -94,6 +96,7 @@ class NetworkTimerSynchronizer`
`94`	`96`	`UserConfigParams::m_timer_sync_difference_tolerance)`
`95`	`97`	`{`
`96`	`98`	`STKHost::get()->setNetworkTimer(averaged_time);`
	`99`	`+ m_times.clear();`
`97`	`100`	`m_force_set_timer.store(false);`
`98`	`101`	`m_synchronised.store(true);`
`99`	`102`	`Log::info("NetworkTimerSynchronizer", "Network "`