Fix Lua memory usage

components/lua/scripttracker.cpp

@@ -0,0 +1,53 @@
+#include "scripttracker.hpp"
+
+namespace LuaUtil
+{
+    namespace
+    {
+        constexpr unsigned sMinLoadedFrames = 50;
+        constexpr unsigned sMaxLoadedFrames = 600;
+        constexpr unsigned sUsageFrameGrowth = 10;
+        constexpr std::size_t sMinToProcess = 1;
+        constexpr std::size_t sToProcessDiv = 20; // 5%
+    }
+
+    void ScriptTracker::onLoad(ScriptsContainer& container)
+    {
+        mLoadedScripts.emplace(container.mThis, sMinLoadedFrames + mFrame);
+    }
+
+    void ScriptTracker::unloadInactiveScripts(LuaView& lua)
+    {
+        // This code is technically incorrect if mFrame overflows... but at 300fps that takes about half a year
+        std::size_t toProcess = std::max(mLoadedScripts.size() / sToProcessDiv, sMinToProcess);
+        while (toProcess && !mLoadedScripts.empty())
+        {
+            --toProcess;
+            auto [ptr, ttl] = std::move(mLoadedScripts.front());
+            mLoadedScripts.pop();
+            ScriptsContainer* container = *ptr.get();
+            // Object no longer exists, cease tracking
+            if (!container)
+                continue;
+            // Ignore activity of local scripts in the active grid
+            if (container->isActive())
+                ttl = std::max(ttl, mFrame + sMinLoadedFrames);
+            else
+            {
+                bool activeSinceLastPop = container->mRequiredLoading;
+                if (activeSinceLastPop)
+                {
+                    container->mRequiredLoading = false;
+                    ttl = std::min(ttl + sUsageFrameGrowth, mFrame + sMaxLoadedFrames);
+                }
+                else if (ttl < mFrame)
+                {
+                    container->ensureUnloaded(lua);
+                    continue;
+                }
+            }
+            mLoadedScripts.emplace(std::move(ptr), ttl);
+        }
+        ++mFrame;
+    }
+}