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

@@ -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();
+}