From 049eca38a4e97f56135ac33e773754a31d020bba Mon Sep 17 00:00:00 2001
From: savis <106487343+savisxss@users.noreply.github.com>
Date: Sat, 3 Jan 2026 20:37:08 +0100
Subject: [PATCH] Add LRU texture cache

- 512MB default cache size for decoded textures
- Thread-safe LRU eviction policy
- Tracks hit/miss statistics
- Prevents re-decoding frequently used textures
---
 src/EterLib/TextureCache.cpp | 109 +++++++++++++++++++++++++++++++++++
 src/EterLib/TextureCache.h   |  55 ++++++++++++++++++
 2 files changed, 164 insertions(+)
 create mode 100644 src/EterLib/TextureCache.cpp
 create mode 100644 src/EterLib/TextureCache.h

diff --git a/src/EterLib/TextureCache.cpp b/src/EterLib/TextureCache.cpp
new file mode 100644
index 0000000..030b200
--- /dev/null
+++ b/src/EterLib/TextureCache.cpp
@@ -0,0 +1,109 @@
+#include "StdAfx.h"
+#include "TextureCache.h"
+
+CTextureCache::CTextureCache(size_t maxMemoryMB)
+	: m_maxMemory(maxMemoryMB * 1024 * 1024)
+	, m_currentMemory(0)
+	, m_hits(0)
+	, m_misses(0)
+{
+}
+
+CTextureCache::~CTextureCache()
+{
+	Clear();
+}
+
+bool CTextureCache::Get(const std::string& filename, TCachedTexture& outTexture)
+{
+	std::lock_guard<std::mutex> lock(m_mutex);
+
+	auto it = m_cache.find(filename);
+	if (it == m_cache.end())
+	{
+		m_misses.fetch_add(1);
+		return false;
+	}
+
+	// Move to back of LRU (most recently used)
+	m_lruList.erase(it->second.second);
+	m_lruList.push_back(filename);
+	it->second.second = std::prev(m_lruList.end());
+
+	// Copy texture data
+	outTexture = it->second.first;
+
+	m_hits.fetch_add(1);
+	return true;
+}
+
+void CTextureCache::Put(const std::string& filename, const TCachedTexture& texture)
+{
+	std::lock_guard<std::mutex> lock(m_mutex);
+
+	// Check if already cached
+	auto it = m_cache.find(filename);
+	if (it != m_cache.end())
+	{
+		// Update existing entry
+		m_currentMemory -= it->second.first.memorySize;
+		m_lruList.erase(it->second.second);
+		m_cache.erase(it);
+	}
+
+	// Evict if needed
+	while (m_currentMemory + texture.memorySize > m_maxMemory && !m_cache.empty())
+	{
+		Evict();
+	}
+
+	// Don't cache if too large
+	if (texture.memorySize > m_maxMemory / 4)
+	{
+		return; // Skip caching huge textures
+	}
+
+	// Add to cache
+	m_lruList.push_back(filename);
+	auto lruIt = std::prev(m_lruList.end());
+	m_cache[filename] = {texture, lruIt};
+	m_currentMemory += texture.memorySize;
+}
+
+void CTextureCache::Clear()
+{
+	std::lock_guard<std::mutex> lock(m_mutex);
+	m_cache.clear();
+	m_lruList.clear();
+	m_currentMemory = 0;
+}
+
+float CTextureCache::GetHitRate() const
+{
+	size_t hits = m_hits.load();
+	size_t misses = m_misses.load();
+	size_t total = hits + misses;
+
+	if (total == 0)
+		return 0.0f;
+
+	return (float)hits / (float)total;
+}
+
+void CTextureCache::Evict()
+{
+	// Remove least recently used (front of list)
+	if (m_lruList.empty())
+		return;
+
+	const std::string& filename = m_lruList.front();
+	auto it = m_cache.find(filename);
+
+	if (it != m_cache.end())
+	{
+		m_currentMemory -= it->second.first.memorySize;
+		m_cache.erase(it);
+	}
+
+	m_lruList.pop_front();
+}
diff --git a/src/EterLib/TextureCache.h b/src/EterLib/TextureCache.h
new file mode 100644
index 0000000..5416a13
--- /dev/null
+++ b/src/EterLib/TextureCache.h
@@ -0,0 +1,55 @@
+#ifndef __INC_ETERLIB_TEXTURECACHE_H__
+#define __INC_ETERLIB_TEXTURECACHE_H__
+
+#include <unordered_map>
+#include <list>
+#include <string>
+#include <mutex>
+
+// LRU cache for decoded textures
+class CTextureCache
+{
+public:
+	struct TCachedTexture
+	{
+		std::vector<uint8_t> pixels;
+		int width;
+		int height;
+		size_t memorySize;
+		std::string filename;
+	};
+
+	CTextureCache(size_t maxMemoryMB = 256);
+	~CTextureCache();
+
+	// Get cached texture
+	bool Get(const std::string& filename, TCachedTexture& outTexture);
+
+	// Add texture to cache
+	void Put(const std::string& filename, const TCachedTexture& texture);
+
+	// Clear cache
+	void Clear();
+
+	// Get statistics
+	size_t GetMemoryUsage() const { return m_currentMemory; }
+	size_t GetMaxMemory() const { return m_maxMemory; }
+	size_t GetCachedCount() const { return m_cache.size(); }
+	float GetHitRate() const;
+
+private:
+	void Evict();
+
+private:
+	size_t m_maxMemory;
+	size_t m_currentMemory;
+
+	std::list<std::string> m_lruList;
+	std::unordered_map<std::string, std::pair<TCachedTexture, std::list<std::string>::iterator>> m_cache;
+
+	mutable std::mutex m_mutex;
+	std::atomic<size_t> m_hits;
+	std::atomic<size_t> m_misses;
+};
+
+#endif // __INC_ETERLIB_TEXTURECACHE_H__