From 32cef906b02562ffb129b095386a9314abde82f1 Mon Sep 17 00:00:00 2001
From: Shauren <shauren.trinity@gmail.com>
Date: Mon, 3 Jan 2022 11:26:23 +0100
Subject: Core/Time: Remove artificially high minimal update intervals

(cherry picked from commit 3a67e376811743be208da4aab8a9e452e1ae637e)
---
 src/server/worldserver/Main.cpp | 55 +++++++++++++++++++++++++++++++++++------
 1 file changed, 48 insertions(+), 7 deletions(-)

(limited to 'src/server/worldserver/Main.cpp')

diff --git a/src/server/worldserver/Main.cpp b/src/server/worldserver/Main.cpp
index 418b5de5eb1..888b0ad65d4 100644
--- a/src/server/worldserver/Main.cpp
+++ b/src/server/worldserver/Main.cpp
@@ -67,7 +67,7 @@ namespace fs = boost::filesystem;
     #define _TRINITY_CORE_CONFIG  "worldserver.conf"
 #endif
 
-#define WORLD_SLEEP_CONST 50
+#define WORLD_SLEEP_CONST 1
 
 #ifdef _WIN32
 #include "ServiceWin32.h"
@@ -81,6 +81,9 @@ char serviceDescription[] = "TrinityCore World of Warcraft emulator world servic
  *  2 - paused
  */
 int m_ServiceStatus = -1;
+
+#include <boost/dll/shared_library.hpp>
+#include <timeapi.h>
 #endif
 
 class FreezeDetector
@@ -135,6 +138,44 @@ extern int main(int argc, char** argv)
         return WinServiceUninstall() == true ? 0 : 1;
     else if (configService.compare("run") == 0)
         WinServiceRun();
+
+    Optional<UINT> newTimerResolution;
+    boost::system::error_code dllError;
+    std::shared_ptr<boost::dll::shared_library> winmm(new boost::dll::shared_library("winmm.dll", dllError, boost::dll::load_mode::search_system_folders), [&](boost::dll::shared_library* lib)
+    {
+        try
+        {
+            if (newTimerResolution)
+                lib->get<decltype(timeEndPeriod)>("timeEndPeriod")(*newTimerResolution);
+        }
+        catch (std::exception const&)
+        {
+            // ignore
+        }
+
+        delete lib;
+    });
+
+    if (winmm->is_loaded())
+    {
+        try
+        {
+            auto timeGetDevCapsPtr = winmm->get<decltype(timeGetDevCaps)>("timeGetDevCaps");
+            // setup timer resolution
+            TIMECAPS timeResolutionLimits;
+            if (timeGetDevCapsPtr(&timeResolutionLimits, sizeof(TIMECAPS)) == TIMERR_NOERROR)
+            {
+                auto timeBeginPeriodPtr = winmm->get<decltype(timeBeginPeriod)>("timeBeginPeriod");
+                newTimerResolution = std::min(std::max(timeResolutionLimits.wPeriodMin, 1u), timeResolutionLimits.wPeriodMax);
+                timeBeginPeriodPtr(*newTimerResolution);
+            }
+        }
+        catch (std::exception const& e)
+        {
+            printf("Failed to initialize timer resolution: %s\n", e.what());
+        }
+    }
+
 #endif
 
     std::string configError;
@@ -445,16 +486,16 @@ void WorldUpdateLoop()
         realCurrTime = getMSTime();
 
         uint32 diff = getMSTimeDiff(realPrevTime, realCurrTime);
+        if (!diff)
+        {
+            // sleep until enough time passes that we can update all timers
+            std::this_thread::sleep_for(std::chrono::milliseconds(1));
+            continue;
+        }
 
         sWorld->Update(diff);
         realPrevTime = realCurrTime;
 
-        uint32 executionTimeDiff = getMSTimeDiff(realCurrTime, getMSTime());
-
-        // we know exactly how long it took to update the world, if the update took less than WORLD_SLEEP_CONST, sleep for WORLD_SLEEP_CONST - world update time
-        if (executionTimeDiff < WORLD_SLEEP_CONST)
-            std::this_thread::sleep_for(std::chrono::milliseconds(WORLD_SLEEP_CONST - executionTimeDiff));
-
 #ifdef _WIN32
         if (m_ServiceStatus == 0)
             World::StopNow(SHUTDOWN_EXIT_CODE);
-- 
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