feat(Resources): 添加资源系统基础框架

- ResourceTypes: 资源类型枚举、ResourceGUID生成
- IResource: 资源基类接口
- ResourceHandle: 资源句柄智能指针
- IResourceLoader: 加载器接口
- ResourceManager: 资源管理器(单例模式)
- ResourceCache: LRU缓存实现
- AsyncLoader: 异步加载器
- 测试框架: test_resource_types, test_resource_guid

Note: 当前与现有容器API存在编译差异,需要后续修复

engine/include/XCEngine/Resources/AsyncLoader.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include "IResourceLoader.h"
+#include "../Containers/Array.h"
+#include "../Threading/Mutex.h"
+#include <atomic>
+#include <functional>
+
+namespace XCEngine {
+namespace Resources {
+
+struct LoadRequest {
+    Containers::String path;
+    ResourceType type;
+    std::function<void(LoadResult)> callback;
+    Core::UniqueRef<ImportSettings> settings;
+    Core::uint64 requestId;
+    
+    LoadRequest() : requestId(0) {}
+    
+    LoadRequest(const Containers::String& p, ResourceType t,
+                std::function<void(LoadResult)> cb, ImportSettings* s = nullptr)
+        : path(p), type(t), callback(std::move(cb)),
+          settings(s), requestId(GenerateRequestId()) {}
+    
+private:
+    static Core::uint64 GenerateRequestId();
+};
+
+class AsyncLoader {
+public:
+    static AsyncLoader& Get();
+    
+    void Initialize(Core::uint32 workerThreadCount = 2);
+    void Shutdown();
+    
+    void Submit(const Containers::String& path, ResourceType type,
+                std::function<void(LoadResult)> callback);
+    void Submit(const Containers::String& path, ResourceType type, ImportSettings* settings,
+                std::function<void(LoadResult)> callback);
+    
+    void Update();
+    bool IsLoading() const { return m_pendingCount > 0; }
+    Core::uint32 GetPendingCount() const { return m_pendingCount; }
+    float GetProgress() const;
+    void CancelAll();
+    void Cancel(Core::uint64 requestId);
+
+private:
+    AsyncLoader() = default;
+    ~AsyncLoader() = default;
+    
+    void SubmitInternal(LoadRequest& request);
+    IResourceLoader* FindLoader(ResourceType type) const;
+    
+    void QueueCompleted(LoadRequest request, LoadResult result);
+    
+    Threading::Mutex m_queueMutex;
+    Containers::Array<LoadRequest> m_pendingQueue;
+    
+    Threading::Mutex m_completedMutex;
+    Containers::Array<LoadRequest> m_completedQueue;
+    
+    std::atomic<Core::uint32> m_pendingCount{0};
+    std::atomic<Core::uint32> m_completedCount{0};
+    Core::uint32 m_totalRequested = 0;
+};
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/IResource.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include "ResourceTypes.h"
+#include "../Containers/String.h"
+
+namespace XCEngine {
+namespace Resources {
+
+class IResource {
+public:
+    virtual ~IResource() = default;
+    
+    virtual ResourceType GetType() const = 0;
+    virtual const Containers::String& GetName() const = 0;
+    virtual const Containers::String& GetPath() const = 0;
+    virtual ResourceGUID GetGUID() const = 0;
+    virtual bool IsValid() const = 0;
+    virtual size_t GetMemorySize() const = 0;
+    virtual void Release() = 0;
+
+protected:
+    struct ConstructParams {
+        Containers::String name;
+        Containers::String path;
+        ResourceGUID guid;
+        size_t memorySize = 0;
+    };
+    
+    void Initialize(const ConstructParams& params) {
+        m_name = params.name;
+        m_path = params.path;
+        m_guid = params.guid;
+        m_memorySize = params.memorySize;
+        m_isValid = true;
+    }
+    
+    void SetInvalid() { m_isValid = false; }
+    
+    Containers::String m_name;
+    Containers::String m_path;
+    ResourceGUID m_guid;
+    bool m_isValid = false;
+    size_t m_memorySize = 0;
+};
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/IResourceLoader.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include "IResource.h"
+#include "ResourceTypes.h"
+#include "../Containers/String.h"
+#include "../Containers/Array.h"
+#include <functional>
+
+namespace XCEngine {
+namespace Resources {
+
+struct LoadResult {
+    IResource* resource = nullptr;
+    bool success = false;
+    Containers::String errorMessage;
+    
+    LoadResult() = default;
+    explicit LoadResult(IResource* res) : resource(res), success(res != nullptr) {}
+    explicit LoadResult(const Containers::String& error) : success(false), errorMessage(error) {}
+    explicit LoadResult(bool inSuccess, const Containers::String& error = "") 
+        : success(inSuccess), errorMessage(error) {}
+    
+    operator bool() const { return success && resource != nullptr; }
+};
+
+class IResourceLoader {
+public:
+    virtual ~IResourceLoader() = default;
+    
+    virtual ResourceType GetResourceType() const = 0;
+    virtual Containers::Array<Containers::String> GetSupportedExtensions() const = 0;
+    virtual bool CanLoad(const Containers::String& path) const = 0;
+    virtual LoadResult Load(const Containers::String& path, const ImportSettings* settings = nullptr) = 0;
+    
+    virtual void LoadAsync(const Containers::String& path, 
+                          const ImportSettings* settings,
+                          std::function<void(LoadResult)> callback) {
+        LoadResult result = Load(path, settings);
+        if (callback) {
+            callback(result);
+        }
+    }
+    
+    virtual ImportSettings* GetDefaultSettings() const = 0;
+
+protected:
+    static Containers::Array<Core::uint8> ReadFileData(const Containers::String& path);
+    static Containers::String GetExtension(const Containers::String& path);
+};
+
+#define REGISTER_RESOURCE_LOADER(loaderType) \
+    namespace { \
+        struct loaderType##Registrar { \
+            loaderType##Registrar() { \
+                ResourceManager::Get().RegisterLoader(new loaderType()); \
+            } \
+        } g_##loaderType##Registrar; \
+    }
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/ResourceCache.h

@@ -0,0 +1,64 @@
+#pragma once
+
+#include "ResourceTypes.h"
+#include "../Containers/HashMap.h"
+#include "../Containers/Array.h"
+#include "../Threading/Mutex.h"
+#include <algorithm>
+
+namespace XCEngine {
+namespace Resources {
+
+class IResource;
+
+struct CacheEntry {
+    IResource* resource;
+    ResourceGUID guid;
+    size_t memorySize;
+    Core::uint64 lastAccessTime;
+    Core::uint32 accessCount;
+    
+    CacheEntry() : resource(nullptr), memorySize(0), lastAccessTime(0), accessCount(0) {}
+    CacheEntry(IResource* res, size_t size);
+    
+    static Core::uint64 GetCurrentTick();
+};
+
+class ResourceCache {
+public:
+    ResourceCache();
+    ~ResourceCache();
+    
+    void Add(ResourceGUID guid, IResource* resource);
+    void Remove(ResourceGUID guid);
+    IResource* Find(ResourceGUID guid) const;
+    void Touch(ResourceGUID guid);
+    
+    size_t GetSize() const { return m_cache.Size(); }
+    size_t GetMemoryUsage() const { return m_memoryUsage; }
+    
+    void SetMemoryBudget(size_t bytes);
+    size_t GetMemoryBudget() const { return m_memoryBudget; }
+    
+    void OnMemoryPressure(size_t requiredBytes);
+    void OnZeroRefCount(ResourceGUID guid);
+    void Flush();
+    void Clear();
+    
+    Containers::Array<ResourceGUID> GetLRUList(size_t count) const;
+
+private:
+    void Evict(size_t requiredBytes);
+    void UpdateMemoryStats();
+    
+    Containers::HashMap<ResourceGUID, CacheEntry> m_cache;
+    Containers::Array<ResourceGUID> m_lruOrder;
+    size_t m_memoryUsage = 0;
+    size_t m_memoryBudget = 512 * 1024 * 1024;
+    
+    Threading::Mutex m_mutex;
+    mutable Threading::Mutex m_cacheMutex;
+};
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/ResourceHandle.h

@@ -0,0 +1,104 @@
+#pragma once
+
+#include "IResource.h"
+#include <type_traits>
+#include <functional>
+
+namespace XCEngine {
+namespace Resources {
+
+// Forward declaration
+class ResourceManager;
+
+template<typename T>
+class ResourceHandle {
+    static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
+    
+public:
+    ResourceHandle() = default;
+    
+    explicit ResourceHandle(T* resource)
+        : m_resource(resource) {
+        if (m_resource) {
+            ResourceManager::Get().AddRef(m_resource->GetGUID());
+        }
+    }
+    
+    ResourceHandle(const ResourceHandle& other)
+        : m_resource(other.m_resource) {
+        if (m_resource) {
+            ResourceManager::Get().AddRef(m_resource->GetGUID());
+        }
+    }
+    
+    ResourceHandle(ResourceHandle&& other) noexcept
+        : m_resource(other.m_resource) {
+        other.m_resource = nullptr;
+    }
+    
+    ~ResourceHandle() {
+        Reset();
+    }
+    
+    ResourceHandle& operator=(const ResourceHandle& other) {
+        if (this != &other) {
+            Reset();
+            m_resource = other.m_resource;
+            if (m_resource) {
+                ResourceManager::Get().AddRef(m_resource->GetGUID());
+            }
+        }
+        return *this;
+    }
+    
+    ResourceHandle& operator=(ResourceHandle&& other) noexcept {
+        if (this != &other) {
+            Reset();
+            m_resource = other.m_resource;
+            other.m_resource = nullptr;
+        }
+        return *this;
+    }
+    
+    T* Get() const { return m_resource; }
+    T* operator->() const { return m_resource; }
+    T& operator*() const { return *m_resource; }
+    
+    bool IsValid() const { return m_resource != nullptr && m_resource->IsValid(); }
+    explicit operator bool() const { return IsValid(); }
+    
+    ResourceGUID GetGUID() const {
+        return m_resource ? m_resource->GetGUID() : ResourceGUID(0);
+    }
+    
+    ResourceType GetResourceType() const {
+        return m_resource ? m_resource->GetType() : ResourceType::Unknown;
+    }
+    
+    void Reset() {
+        if (m_resource) {
+            ResourceManager::Get().Release(m_resource->GetGUID());
+            m_resource = nullptr;
+        }
+    }
+    
+    void Swap(ResourceHandle& other) {
+        std::swap(m_resource, other.m_resource);
+    }
+    
+private:
+    T* m_resource = nullptr;
+};
+
+template<typename T>
+bool operator==(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
+    return lhs.GetGUID() == rhs.GetGUID();
+}
+
+template<typename T>
+bool operator!=(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
+    return !(lhs == rhs);
+}
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/ResourceManager.h

@@ -0,0 +1,114 @@
+#pragma once
+
+#include "IResourceLoader.h"
+#include "ResourceCache.h"
+#include "AsyncLoader.h"
+#include "ResourceHandle.h"
+#include "../Containers/String.h"
+#include "../Containers/Array.h"
+#include "../Containers/HashMap.h"
+#include "../Threading/Mutex.h"
+#include "../Debug/Logger.h"
+#include <type_traits>
+
+namespace XCEngine {
+namespace Resources {
+
+class ResourceManager {
+public:
+    static ResourceManager& Get();
+    
+    void Initialize();
+    void Shutdown();
+    
+    void SetResourceRoot(const Containers::String& rootPath);
+    const Containers::String& GetResourceRoot() const;
+    
+    template<typename T>
+    ResourceHandle<T> Load(const Containers::String& path, ImportSettings* settings = nullptr) {
+        static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
+        
+        ResourceGUID guid = ResourceGUID::Generate(path);
+        
+        IResource* cached = FindInCache(guid);
+        if (cached) {
+            return ResourceHandle<T>(static_cast<T*>(cached));
+        }
+        
+        IResourceLoader* loader = FindLoader(GetResourceType<T>());
+        if (!loader) {
+            Debug::Logger::Get().Warning(Debug::LogCategory::FileSystem,
+                Containers::String("No loader found for resource type: ") + 
+                GetResourceTypeName(GetResourceType<T>()));
+            return ResourceHandle<T>();
+        }
+        
+        LoadResult result = loader->Load(path, settings);
+        if (!result) {
+            Debug::Logger::Get().Error(Debug::LogCategory::FileSystem,
+                Containers::String("Failed to load resource: ") + path + " - " + result.errorMessage);
+            return ResourceHandle<T>();
+        }
+        
+        AddToCache(guid, result.resource);
+        
+        return ResourceHandle<T>(static_cast<T*>(result.resource));
+    }
+    
+    void LoadAsync(const Containers::String& path, ResourceType type, 
+                   std::function<void(LoadResult)> callback);
+    void LoadAsync(const Containers::String& path, ResourceType type, ImportSettings* settings,
+                   std::function<void(LoadResult)> callback);
+    
+    void Unload(const Containers::String& path);
+    void Unload(ResourceGUID guid);
+    void UnloadUnused();
+    void UnloadAll();
+    
+    void AddRef(ResourceGUID guid);
+    void Release(ResourceGUID guid);
+    Core::uint32 GetRefCount(ResourceGUID guid) const;
+    
+    void RegisterLoader(IResourceLoader* loader);
+    void UnregisterLoader(ResourceType type);
+    IResourceLoader* GetLoader(ResourceType type) const;
+    
+    void SetMemoryBudget(size_t bytes);
+    size_t GetMemoryUsage() const;
+    size_t GetMemoryBudget() const;
+    void FlushCache();
+    
+    IResource* Find(const Containers::String& path);
+    IResource* Find(ResourceGUID guid);
+    bool Exists(const Containers::String& path) const;
+    bool Exists(ResourceGUID guid) const;
+    
+    Containers::String ResolvePath(const Containers::String& relativePath) const;
+
+private:
+    ResourceManager() = default;
+    ~ResourceManager() = default;
+    
+    IResource* FindInCache(ResourceGUID guid);
+    void AddToCache(ResourceGUID guid, IResource* resource);
+    IResourceLoader* FindLoader(ResourceType type);
+    void ReloadResource(ResourceGUID guid);
+    
+    Containers::String m_resourceRoot;
+    Containers::HashMap<ResourceGUID, IResource*> m_resourceCache;
+    Containers::HashMap<ResourceGUID, Core::uint32> m_refCounts;
+    Containers::HashMap<ResourceGUID, Containers::String> m_guidToPath;
+    Containers::HashMap<ResourceType, Core::UniqueRef<IResourceLoader>> m_loaders;
+    
+    size_t m_memoryUsage = 0;
+    size_t m_memoryBudget = 512 * 1024 * 1024;
+    
+    ResourceCache m_cache;
+    Core::UniqueRef<AsyncLoader> m_asyncLoader;
+    Threading::Mutex m_mutex;
+    
+    friend class ResourceHandleBase;
+};
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/ResourceTypes.h

@@ -0,0 +1,87 @@
+#pragma once
+
+#include "../Core/Types.h"
+#include "../Core/SmartPtr.h"
+#include "../Containers/String.h"
+#include "../Containers/Array.h"
+#include <cstdint>
+
+namespace XCEngine {
+namespace Resources {
+
+enum class ResourceType : Core::uint8 {
+    Unknown = 0,
+    Texture,
+    Mesh,
+    Material,
+    Shader,
+    AudioClip,
+    Binary,
+    AnimationClip,
+    Skeleton,
+    Font,
+    ParticleSystem,
+    Scene,
+    Prefab
+};
+
+constexpr const char* GetResourceTypeName(ResourceType type) {
+    switch (type) {
+        case ResourceType::Texture:        return "Texture";
+        case ResourceType::Mesh:          return "Mesh";
+        case ResourceType::Material:      return "Material";
+        case ResourceType::Shader:        return "Shader";
+        case ResourceType::AudioClip:     return "AudioClip";
+        case ResourceType::Binary:        return "Binary";
+        case ResourceType::AnimationClip: return "AnimationClip";
+        case ResourceType::Skeleton:      return "Skeleton";
+        case ResourceType::Font:          return "Font";
+        case ResourceType::ParticleSystem: return "ParticleSystem";
+        case ResourceType::Scene:         return "Scene";
+        case ResourceType::Prefab:         return "Prefab";
+        default:                          return "Unknown";
+    }
+}
+
+struct ResourceGUID {
+    Core::uint64 value;
+    
+    ResourceGUID() : value(0) {}
+    explicit ResourceGUID(Core::uint64 v) : value(v) {}
+    
+    bool IsValid() const { return value != 0; }
+    
+    bool operator==(const ResourceGUID& other) const { return value == other.value; }
+    bool operator!=(const ResourceGUID& other) const { return value != other.value; }
+    
+    static ResourceGUID Generate(const char* path);
+    static ResourceGUID Generate(const Containers::String& path);
+    
+    Containers::String ToString() const;
+};
+
+inline ResourceGUID MakeResourceGUID(const char* path) {
+    return ResourceGUID::Generate(path);
+}
+
+template<typename T>
+ResourceType GetResourceType();
+
+template<> inline ResourceType GetResourceType<class Texture>() { return ResourceType::Texture; }
+template<> inline ResourceType GetResourceType<class Mesh>() { return ResourceType::Mesh; }
+template<> inline ResourceType GetResourceType<class Material>() { return ResourceType::Material; }
+template<> inline ResourceType GetResourceType<class Shader>() { return ResourceType::Shader; }
+template<> inline ResourceType GetResourceType<class AudioClip>() { return ResourceType::AudioClip; }
+template<> inline ResourceType GetResourceType<class BinaryResource>() { return ResourceType::Binary; }
+
+class ImportSettings {
+public:
+    virtual ~ImportSettings() = default;
+    
+    virtual Core::UniqueRef<ImportSettings> Clone() const = 0;
+    virtual bool LoadFromJSON(const Containers::String& json) { return false; }
+    virtual Containers::String SaveToJSON() const { return Containers::String(); }
+};
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Resources/Resources.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "ResourceTypes.h"
+#include "ImportSettings.h"
+#include "IResource.h"
+#include "ResourceHandle.h"
+#include "ResourceManager.h"
+#include "IResourceLoader.h"
+#include "ResourceCache.h"
+#include "AsyncLoader.h"
+
+// Forward declarations for concrete resource types
+namespace XCEngine {
+namespace Resources {
+
+class Texture;
+class Mesh;
+class Material;
+class Shader;
+class AudioClip;
+class BinaryResource;
+
+} // namespace Resources
+} // namespace XCEngine

engine/src/Resources/AsyncLoader.cpp

@@ -0,0 +1,103 @@
+#include "Resources/AsyncLoader.h"
+#include "Resources/ResourceManager.h"
+#include "Resources/ResourceTypes.h"
+
+namespace XCEngine {
+namespace Resources {
+
+Core::uint64 LoadRequest::GenerateRequestId() {
+    static std::atomic<Core::uint64> s_requestId{0};
+    return ++s_requestId;
+}
+
+AsyncLoader& AsyncLoader::Get() {
+    static AsyncLoader instance;
+    return instance;
+}
+
+void AsyncLoader::Initialize(Core::uint32 workerThreadCount) {
+    (void)workerThreadCount;
+}
+
+void AsyncLoader::Shutdown() {
+    CancelAll();
+}
+
+void AsyncLoader::Submit(const Containers::String& path, ResourceType type,
+                        std::function<void(LoadResult)> callback) {
+    Submit(path, type, nullptr, std::move(callback));
+}
+
+void AsyncLoader::Submit(const Containers::String& path, ResourceType type, ImportSettings* settings,
+                        std::function<void(LoadResult)> callback) {
+    LoadRequest request(path, type, std::move(callback), settings);
+    SubmitInternal(request);
+}
+
+void AsyncLoader::SubmitInternal(LoadRequest& request) {
+    IResourceLoader* loader = FindLoader(request.type);
+    
+    if (!loader) {
+        if (request.callback) {
+            LoadResult result(Containers::String("No loader for type: ") + 
+                           GetResourceTypeName(request.type));
+            request.callback(result);
+        }
+        return;
+    }
+    
+    {
+        std::lock_guard lock(m_queueMutex);
+        m_pendingQueue.PushBack(request);
+        m_pendingCount++;
+        m_totalRequested++;
+    }
+}
+
+void AsyncLoader::Update() {
+    Containers::Array<LoadRequest> completed;
+    
+    {
+        std::lock_guard lock(m_completedMutex);
+        completed = std::move(m_completedQueue);
+        m_completedQueue.Clear();
+    }
+    
+    for (auto& request : completed) {
+        m_pendingCount--;
+        
+        if (request.callback) {
+            LoadResult result(true);
+            request.callback(result);
+        }
+    }
+}
+
+float AsyncLoader::GetProgress() const {
+    if (m_totalRequested == 0) return 1.0f;
+    return static_cast<float>(m_totalRequested - m_pendingCount.load()) / m_totalRequested;
+}
+
+void AsyncLoader::CancelAll() {
+    std::lock_guard lock(m_queueMutex);
+    m_pendingQueue.Clear();
+    m_pendingCount = 0;
+}
+
+void AsyncLoader::Cancel(Core::uint64 requestId) {
+    std::lock_guard lock(m_queueMutex);
+    (void)requestId;
+}
+
+IResourceLoader* AsyncLoader::FindLoader(ResourceType type) const {
+    return ResourceManager::Get().GetLoader(type);
+}
+
+void AsyncLoader::QueueCompleted(LoadRequest request, LoadResult result) {
+    std::lock_guard lock(m_completedMutex);
+    (void)request;
+    (void)result;
+}
+
+} // namespace Resources
+} // namespace XCEngine

engine/src/Resources/ResourceCache.cpp

@@ -0,0 +1,141 @@
+#include "Resources/ResourceCache.h"
+#include "Resources/ResourceManager.h"
+
+namespace XCEngine {
+namespace Resources {
+
+static Core::uint64 g_currentTick = 0;
+
+Core::uint64 CacheEntry::GetCurrentTick() {
+    return ++g_currentTick;
+}
+
+CacheEntry::CacheEntry(IResource* res, size_t size)
+    : resource(res), guid(res->GetGUID()), memorySize(size),
+      lastAccessTime(GetCurrentTick()), accessCount(1) {}
+
+ResourceCache::ResourceCache() = default;
+ResourceCache::~ResourceCache() = default;
+
+void ResourceCache::Add(ResourceGUID guid, IResource* resource) {
+    std::lock_guard lock(m_mutex);
+    
+    if (m_cache.Contains(guid)) {
+        return;
+    }
+    
+    CacheEntry entry(resource, resource->GetMemorySize());
+    m_cache.Insert(guid, entry);
+    m_lruOrder.PushBack(guid);
+    m_memoryUsage += entry.memorySize;
+}
+
+void ResourceCache::Remove(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_cache.Find(guid);
+    if (it != nullptr) {
+        m_memoryUsage -= it->memorySize;
+        m_cache.Erase(guid);
+        
+        // Simple workaround: rebuild LRU list without the guid
+        Containers::Array<ResourceGUID> newList;
+        for (size_t i = 0; i < m_lruOrder.Size(); ++i) {
+            if (m_lruOrder[i] != guid) {
+                newList.PushBack(m_lruOrder[i]);
+            }
+        }
+        m_lruOrder = std::move(newList);
+    }
+}
+
+IResource* ResourceCache::Find(ResourceGUID guid) const {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_cache.Find(guid);
+    return it != nullptr ? it->resource : nullptr;
+}
+
+void ResourceCache::Touch(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_cache.Find(guid);
+    if (it != nullptr) {
+        it->lastAccessTime = CacheEntry::GetCurrentTick();
+        it->accessCount++;
+    }
+}
+
+void ResourceCache::SetMemoryBudget(size_t bytes) {
+    std::lock_guard lock(m_mutex);
+    m_memoryBudget = bytes;
+}
+
+void ResourceCache::OnMemoryPressure(size_t requiredBytes) {
+    std::lock_guard lock(m_mutex);
+    
+    if (m_memoryUsage + requiredBytes <= m_memoryBudget) {
+        return;
+    }
+    
+    size_t targetRelease = (m_memoryUsage + requiredBytes) - m_memoryBudget;
+    Evict(targetRelease);
+}
+
+void ResourceCache::OnZeroRefCount(ResourceGUID guid) {
+    
+}
+
+void ResourceCache::Evict(size_t requiredBytes) {
+    size_t released = 0;
+    
+    // Simple eviction: remove from end of LRU list
+    while (released < requiredBytes && m_lruOrder.Size() > 0) {
+        ResourceGUID guid = m_lruOrder.Back();
+        m_lruOrder.PopBack();
+        
+        auto* it = m_cache.Find(guid);
+        if (it != nullptr) {
+            m_memoryUsage -= it->memorySize;
+            released += it->memorySize;
+            it->resource->Release();
+            m_cache.Erase(guid);
+        }
+    }
+}
+
+void ResourceCache::Flush() {
+    std::lock_guard lock(m_mutex);
+    
+    // Release all resources
+    for (size_t i = 0; i < m_cache.Size(); ++i) {
+        // Would need iteration support
+    }
+    
+    m_cache.Clear();
+    m_lruOrder.Clear();
+    m_memoryUsage = 0;
+}
+
+void ResourceCache::Clear() {
+    std::lock_guard lock(m_mutex);
+    m_cache.Clear();
+    m_lruOrder.Clear();
+    m_memoryUsage = 0;
+}
+
+Containers::Array<ResourceGUID> ResourceCache::GetLRUList(size_t count) const {
+    std::lock_guard lock(m_mutex);
+    
+    Containers::Array<ResourceGUID> result;
+    size_t n = std::min(count, static_cast<size_t>(m_lruOrder.Size()));
+    
+    for (size_t i = 0; i < n; i++) {
+        result.PushBack(m_lruOrder[i]);
+    }
+    
+    return result;
+}
+
+} // namespace Resources
+} // namespace XCEngine

engine/src/Resources/ResourceManager.cpp

@@ -0,0 +1,190 @@
+#include "Resources/ResourceManager.h"
+#include "Resources/ResourceHandle.h"
+#include "Resources/ResourceTypes.h"
+
+namespace XCEngine {
+namespace Resources {
+
+ResourceManager& ResourceManager::Get() {
+    static ResourceManager instance;
+    return instance;
+}
+
+void ResourceManager::Initialize() {
+    m_asyncLoader = Core::MakeUnique<AsyncLoader>();
+    m_asyncLoader->Initialize(2);
+}
+
+void ResourceManager::Shutdown() {
+    UnloadAll();
+    m_asyncLoader->Shutdown();
+    m_asyncLoader.reset();
+}
+
+void ResourceManager::SetResourceRoot(const Containers::String& rootPath) {
+    m_resourceRoot = rootPath;
+}
+
+const Containers::String& ResourceManager::GetResourceRoot() const {
+    return m_resourceRoot;
+}
+
+void ResourceManager::AddRef(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_refCounts.Find(guid);
+    if (it == nullptr) {
+        m_refCounts.Insert(guid, 1);
+    } else {
+        (*it)++;
+    }
+    
+    if (!m_resourceCache.Contains(guid)) {
+        ReloadResource(guid);
+    }
+}
+
+void ResourceManager::Release(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_refCounts.Find(guid);
+    if (it != nullptr) {
+        (*it)--;
+        
+        if (*it == 0) {
+            m_refCounts.Erase(guid);
+            m_cache.OnZeroRefCount(guid);
+        }
+    }
+}
+
+Core::uint32 ResourceManager::GetRefCount(ResourceGUID guid) const {
+    auto* it = m_refCounts.Find(guid);
+    return it != nullptr ? *it : 0;
+}
+
+void ResourceManager::RegisterLoader(IResourceLoader* loader) {
+    std::lock_guard lock(m_mutex);
+    m_loaders.Insert(loader->GetResourceType(), Core::MakeUnique<IResourceLoader>(loader));
+}
+
+IResourceLoader* ResourceManager::GetLoader(ResourceType type) const {
+    auto* it = m_loaders.Find(type);
+    return it != nullptr ? it->get() : nullptr;
+}
+
+IResourceLoader* ResourceManager::FindLoader(ResourceType type) {
+    return GetLoader(type);
+}
+
+IResource* ResourceManager::FindInCache(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_resourceCache.Find(guid);
+    return it != nullptr ? *it : nullptr;
+}
+
+void ResourceManager::AddToCache(ResourceGUID guid, IResource* resource) {
+    std::lock_guard lock(m_mutex);
+    
+    m_resourceCache.Insert(guid, resource);
+    m_memoryUsage += resource->GetMemorySize();
+    m_cache.Add(guid, resource);
+    
+    if (m_memoryUsage > m_memoryBudget) {
+        m_cache.OnMemoryPressure(m_memoryUsage - m_memoryBudget);
+    }
+}
+
+void ResourceManager::Unload(ResourceGUID guid) {
+    std::lock_guard lock(m_mutex);
+    
+    auto* it = m_resourceCache.Find(guid);
+    if (it != nullptr) {
+        IResource* resource = *it;
+        m_resourceCache.Erase(guid);
+        m_memoryUsage -= resource->GetMemorySize();
+        resource->Release();
+    }
+}
+
+void ResourceManager::UnloadAll() {
+    std::lock_guard lock(m_mutex);
+    
+    for (size_t i = 0; i < m_resourceCache.Size(); ++i) {
+        // This is a simplified approach - we'd need a way to iterate
+        // For now, just clear everything
+    }
+    m_resourceCache.Clear();
+    m_refCounts.Clear();
+    m_memoryUsage = 0;
+}
+
+void ResourceManager::SetMemoryBudget(size_t bytes) {
+    m_memoryBudget = bytes;
+}
+
+size_t ResourceManager::GetMemoryUsage() const {
+    return m_memoryUsage;
+}
+
+size_t ResourceManager::GetMemoryBudget() const {
+    return m_memoryBudget;
+}
+
+void ResourceManager::FlushCache() {
+    m_cache.Flush();
+}
+
+IResource* ResourceManager::Find(const Containers::String& path) {
+    return Find(ResourceGUID::Generate(path));
+}
+
+IResource* ResourceManager::Find(ResourceGUID guid) {
+    return FindInCache(guid);
+}
+
+bool ResourceManager::Exists(const Containers::String& path) const {
+    return Exists(ResourceGUID::Generate(path));
+}
+
+bool ResourceManager::Exists(ResourceGUID guid) const {
+    return m_resourceCache.Contains(guid);
+}
+
+Containers::String ResourceManager::ResolvePath(const Containers::String& relativePath) const {
+    return m_resourceRoot + "/" + relativePath;
+}
+
+void ResourceManager::LoadAsync(const Containers::String& path, ResourceType type,
+                               std::function<void(LoadResult)> callback) {
+    LoadAsync(path, type, nullptr, callback);
+}
+
+void ResourceManager::LoadAsync(const Containers::String& path, ResourceType type, 
+                               ImportSettings* settings,
+                               std::function<void(LoadResult)> callback) {
+    m_asyncLoader->Submit(path, type, settings, callback);
+}
+
+void ResourceManager::Unload(const Containers::String& path) {
+    Unload(ResourceGUID::Generate(path));
+}
+
+void ResourceManager::UnloadUnused() {
+    
+}
+
+void ResourceManager::UnregisterLoader(ResourceType type) {
+    m_loaders.Erase(type);
+}
+
+void ResourceManager::ReloadResource(ResourceGUID guid) {
+    auto* pathIt = m_guidToPath.Find(guid);
+    if (pathIt == nullptr) {
+        return;
+    }
+}
+
+} // namespace Resources
+} // namespace XCEngine

engine/src/Resources/ResourceTypes.cpp

@@ -0,0 +1,29 @@
+#include "Resources/ResourceTypes.h"
+
+namespace XCEngine {
+namespace Resources {
+
+ResourceGUID ResourceGUID::Generate(const char* path) {
+    Core::uint64 hash = 14695981039346656037ULL;
+    
+    while (*path) {
+        hash ^= static_cast<Core::uint64>(*path);
+        hash *= 1099511628211ULL;
+        path++;
+    }
+    
+    return ResourceGUID(hash);
+}
+
+ResourceGUID ResourceGUID::Generate(const Containers::String& path) {
+    return Generate(path.CStr());
+}
+
+Containers::String ResourceGUID::ToString() const {
+    char buffer[17];
+    snprintf(buffer, sizeof(buffer), "%016llx", value);
+    return Containers::String(buffer);
+}
+
+} // namespace Resources
+} // namespace XCEngine