Upgrade project asset watcher to native Win32 notifications

editor/src/Core/ProjectAssetWatcher.cpp

@@ -1,10 +1,15 @@
+#define WIN32_LEAN_AND_MEAN
 #include "Core/ProjectAssetWatcher.h"
 #include "Core/IProjectManager.h"
+#include "Platform/Win32Utf8.h"
+
+#include <windows.h>
 
 #include <XCEngine/Core/Asset/ResourceManager.h>
 #include <XCEngine/Debug/Logger.h>
 
 #include <algorithm>
+#include <array>
 #include <cctype>
 #include <system_error>
 
@@ -17,6 +22,14 @@ namespace {
 
 constexpr float kScanIntervalSeconds = 0.75f;
 constexpr float kDebounceWindowSeconds = 0.35f;
+constexpr float kNativeRestartIntervalSeconds = 2.0f;
+constexpr DWORD kNativeWatchBufferSize = 64 * 1024;
+constexpr DWORD kNativeNotifyFilter =
+    FILE_NOTIFY_CHANGE_FILE_NAME |
+    FILE_NOTIFY_CHANGE_DIR_NAME |
+    FILE_NOTIFY_CHANGE_SIZE |
+    FILE_NOTIFY_CHANGE_LAST_WRITE |
+    FILE_NOTIFY_CHANGE_CREATION;
 
 std::string NormalizePathKey(const fs::path& path) {
     std::string key = path.lexically_normal().generic_string();
@@ -46,20 +59,44 @@ std::uint64_t GetFileWriteTimeValue(const fs::path& path) {
     return static_cast<std::uint64_t>(writeTime.time_since_epoch().count());
 }
 
+void CloseHandleIfValid(void*& handle) {
+    if (handle == nullptr) {
+        return;
+    }
+
+    CloseHandle(static_cast<HANDLE>(handle));
+    handle = nullptr;
+}
+
+std::string PathToUtf8String(const fs::path& path) {
+    return Platform::WideToUtf8(path.wstring());
+}
+
 } // namespace
 
+ProjectAssetWatcher::~ProjectAssetWatcher() {
+    Detach();
+}
+
 void ProjectAssetWatcher::Attach(const std::string& projectPath) {
     RefreshProjectBinding(projectPath);
 }
 
 void ProjectAssetWatcher::Detach() {
+    StopNativeWatcher();
     m_projectPath.clear();
     m_assetsRoot.clear();
     m_snapshot.clear();
     m_pendingChanges.Clear();
+    {
+        std::lock_guard<std::mutex> lock(m_nativeChangeMutex);
+        m_threadPendingChanges.Clear();
+    }
     m_scanCooldownSeconds = 0.0f;
+    m_nativeRestartCooldownSeconds = 0.0f;
     m_debounceSeconds = 0.0f;
     m_hasPendingRefresh = false;
+    m_pollingResyncRequested.store(false);
 }
 
 void ProjectAssetWatcher::Update(IEditorContext& context, float dt) {
@@ -68,10 +105,23 @@ void ProjectAssetWatcher::Update(IEditorContext& context, float dt) {
         return;
     }
 
-    m_scanCooldownSeconds -= dt;
-    if (m_scanCooldownSeconds <= 0.0f) {
+    ConsumeNativeChanges();
+
+    if (m_pollingResyncRequested.exchange(false)) {
         ScanForChanges();
-        m_scanCooldownSeconds = kScanIntervalSeconds;
+    }
+
+    if (!m_nativeWatcherHealthy.load()) {
+        m_nativeRestartCooldownSeconds -= dt;
+        if (m_nativeRestartCooldownSeconds <= 0.0f) {
+            StartNativeWatcher();
+        }
+
+        m_scanCooldownSeconds -= dt;
+        if (m_scanCooldownSeconds <= 0.0f) {
+            ScanForChanges();
+            m_scanCooldownSeconds = kScanIntervalSeconds;
+        }
     }
 
     if (!m_hasPendingRefresh) {
@@ -89,25 +139,250 @@ void ProjectAssetWatcher::RefreshProjectBinding(const std::string& projectPath)
         return;
     }
 
+    StopNativeWatcher();
     m_projectPath = projectPath;
-    m_assetsRoot = projectPath.empty() ? fs::path() : (fs::path(projectPath) / "Assets");
+    m_assetsRoot = projectPath.empty() ? fs::path() : (fs::path(Platform::Utf8ToWide(projectPath)) / L"Assets");
     m_snapshot.clear();
     m_pendingChanges.Clear();
     m_scanCooldownSeconds = kScanIntervalSeconds;
+    m_nativeRestartCooldownSeconds = 0.0f;
     m_debounceSeconds = 0.0f;
     m_hasPendingRefresh = false;
+    {
+        std::lock_guard<std::mutex> lock(m_nativeChangeMutex);
+        m_threadPendingChanges.Clear();
+    }
+    m_pollingResyncRequested.store(false);
 
     if (!m_assetsRoot.empty()) {
         BuildSnapshot(m_assetsRoot, m_snapshot);
+        StartNativeWatcher();
     }
 }
 
-void ProjectAssetWatcher::ScanForChanges() {
-    Snapshot currentSnapshot;
-    BuildSnapshot(m_assetsRoot, currentSnapshot);
+void ProjectAssetWatcher::StartNativeWatcher() {
+    StopNativeWatcher();
+    m_nativeRestartCooldownSeconds = kNativeRestartIntervalSeconds;
 
-    const ChangeStats changes = DiffSnapshots(m_snapshot, currentSnapshot);
-    m_snapshot = std::move(currentSnapshot);
+    std::error_code ec;
+    if (m_assetsRoot.empty() || !fs::exists(m_assetsRoot, ec) || !fs::is_directory(m_assetsRoot, ec)) {
+        return;
+    }
+
+    HANDLE stopEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
+    if (stopEvent == nullptr) {
+        Debug::Logger::Get().Warning(
+            Debug::LogCategory::FileSystem,
+            (std::string("[ProjectAssetWatcher] Failed to create native watcher stop event. error=") +
+             std::to_string(GetLastError()) +
+             " fallback=polling").c_str());
+        return;
+    }
+
+    HANDLE directoryHandle = CreateFileW(
+        m_assetsRoot.c_str(),
+        FILE_LIST_DIRECTORY,
+        FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+        nullptr,
+        OPEN_EXISTING,
+        FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
+        nullptr);
+    if (directoryHandle == INVALID_HANDLE_VALUE) {
+        const DWORD error = GetLastError();
+        CloseHandle(stopEvent);
+        Debug::Logger::Get().Warning(
+            Debug::LogCategory::FileSystem,
+            (std::string("[ProjectAssetWatcher] Failed to start native watcher for ") +
+             PathToUtf8String(m_assetsRoot) +
+             " error=" +
+             std::to_string(error) +
+             " fallback=polling").c_str());
+        return;
+    }
+
+    m_nativeStopEvent = stopEvent;
+    m_nativeWatcherHealthy.store(true);
+    m_nativeWatcherThread =
+        std::thread(&ProjectAssetWatcher::RunNativeWatcher, this, static_cast<void*>(directoryHandle), m_assetsRoot);
+
+    Debug::Logger::Get().Info(
+        Debug::LogCategory::FileSystem,
+        (std::string("[ProjectAssetWatcher] Started native watcher for ") + PathToUtf8String(m_assetsRoot)).c_str());
+}
+
+void ProjectAssetWatcher::StopNativeWatcher() {
+    m_nativeWatcherHealthy.store(false);
+
+    if (m_nativeStopEvent != nullptr) {
+        SetEvent(static_cast<HANDLE>(m_nativeStopEvent));
+    }
+
+    if (m_nativeWatcherThread.joinable()) {
+        m_nativeWatcherThread.join();
+    }
+
+    CloseHandleIfValid(m_nativeStopEvent);
+}
+
+void ProjectAssetWatcher::RunNativeWatcher(void* directoryHandleRaw, fs::path watchedRoot) {
+    HANDLE directoryHandle = static_cast<HANDLE>(directoryHandleRaw);
+    HANDLE stopEvent = static_cast<HANDLE>(m_nativeStopEvent);
+    HANDLE readEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
+    if (readEvent == nullptr) {
+        Debug::Logger::Get().Warning(
+            Debug::LogCategory::FileSystem,
+            (std::string("[ProjectAssetWatcher] Failed to create native watcher read event for ") +
+             PathToUtf8String(watchedRoot) +
+             " error=" +
+             std::to_string(GetLastError()) +
+             " fallback=polling").c_str());
+        CloseHandle(directoryHandle);
+        m_nativeWatcherHealthy.store(false);
+        m_pollingResyncRequested.store(true);
+        return;
+    }
+
+    std::array<std::byte, kNativeWatchBufferSize> buffer{};
+    while (WaitForSingleObject(stopEvent, 0) != WAIT_OBJECT_0) {
+        ResetEvent(readEvent);
+
+        OVERLAPPED overlapped{};
+        overlapped.hEvent = readEvent;
+        if (!ReadDirectoryChangesW(
+                directoryHandle,
+                buffer.data(),
+                static_cast<DWORD>(buffer.size()),
+                TRUE,
+                kNativeNotifyFilter,
+                nullptr,
+                &overlapped,
+                nullptr)) {
+            const DWORD error = GetLastError();
+            if (error != ERROR_OPERATION_ABORTED) {
+                Debug::Logger::Get().Warning(
+                    Debug::LogCategory::FileSystem,
+                    (std::string("[ProjectAssetWatcher] Native watcher failed for ") +
+                     PathToUtf8String(watchedRoot) +
+                     " error=" +
+                     std::to_string(error) +
+                     " fallback=polling").c_str());
+                m_pollingResyncRequested.store(true);
+            }
+            m_nativeWatcherHealthy.store(false);
+            break;
+        }
+
+        HANDLE waitHandles[] = { stopEvent, readEvent };
+        const DWORD waitResult = WaitForMultipleObjects(2, waitHandles, FALSE, INFINITE);
+        if (waitResult == WAIT_OBJECT_0) {
+            CancelIoEx(directoryHandle, &overlapped);
+            DWORD ignoredBytes = 0;
+            GetOverlappedResult(directoryHandle, &overlapped, &ignoredBytes, TRUE);
+            break;
+        }
+
+        if (waitResult != (WAIT_OBJECT_0 + 1)) {
+            CancelIoEx(directoryHandle, &overlapped);
+            Debug::Logger::Get().Warning(
+                Debug::LogCategory::FileSystem,
+                (std::string("[ProjectAssetWatcher] Native watcher wait failed for ") +
+                 PathToUtf8String(watchedRoot) +
+                 " error=" +
+                 std::to_string(GetLastError()) +
+                 " fallback=polling").c_str());
+            m_nativeWatcherHealthy.store(false);
+            m_pollingResyncRequested.store(true);
+            break;
+        }
+
+        DWORD bytesReturned = 0;
+        if (!GetOverlappedResult(directoryHandle, &overlapped, &bytesReturned, FALSE)) {
+            const DWORD error = GetLastError();
+            if (error == ERROR_NOTIFY_ENUM_DIR) {
+                m_pollingResyncRequested.store(true);
+                continue;
+            }
+            if (error == ERROR_OPERATION_ABORTED) {
+                break;
+            }
+
+            Debug::Logger::Get().Warning(
+                Debug::LogCategory::FileSystem,
+                (std::string("[ProjectAssetWatcher] Native watcher overlapped result failed for ") +
+                 PathToUtf8String(watchedRoot) +
+                 " error=" +
+                 std::to_string(error) +
+                 " fallback=polling").c_str());
+            m_nativeWatcherHealthy.store(false);
+            m_pollingResyncRequested.store(true);
+            break;
+        }
+
+        if (bytesReturned == 0) {
+            m_pollingResyncRequested.store(true);
+            continue;
+        }
+
+        ChangeStats changes;
+        bool requiresResync = false;
+        for (DWORD offset = 0; offset < bytesReturned;) {
+            const auto* notify = reinterpret_cast<const FILE_NOTIFY_INFORMATION*>(
+                reinterpret_cast<const std::byte*>(buffer.data()) + offset);
+
+            switch (notify->Action) {
+                case FILE_ACTION_ADDED:
+                    ++changes.added;
+                    break;
+                case FILE_ACTION_REMOVED:
+                    ++changes.removed;
+                    break;
+                case FILE_ACTION_MODIFIED:
+                    ++changes.modified;
+                    break;
+                case FILE_ACTION_RENAMED_OLD_NAME:
+                    ++changes.removed;
+                    break;
+                case FILE_ACTION_RENAMED_NEW_NAME:
+                    ++changes.added;
+                    break;
+                default:
+                    requiresResync = true;
+                    break;
+            }
+
+            if (notify->NextEntryOffset == 0) {
+                break;
+            }
+
+            offset += notify->NextEntryOffset;
+        }
+
+        if (requiresResync) {
+            m_pollingResyncRequested.store(true);
+        }
+
+        if (changes.HasChanges()) {
+            std::lock_guard<std::mutex> lock(m_nativeChangeMutex);
+            m_threadPendingChanges.Accumulate(changes);
+        }
+    }
+
+    CloseHandle(readEvent);
+    CloseHandle(directoryHandle);
+}
+
+void ProjectAssetWatcher::ConsumeNativeChanges() {
+    ChangeStats changes;
+    {
+        std::lock_guard<std::mutex> lock(m_nativeChangeMutex);
+        changes = m_threadPendingChanges;
+        m_threadPendingChanges.Clear();
+    }
+
+    ScheduleRefresh(changes);
+}
+
+void ProjectAssetWatcher::ScheduleRefresh(const ChangeStats& changes) {
     if (!changes.HasChanges()) {
         return;
     }
@@ -117,6 +392,15 @@ void ProjectAssetWatcher::ScanForChanges() {
     m_debounceSeconds = kDebounceWindowSeconds;
 }
 
+void ProjectAssetWatcher::ScanForChanges() {
+    Snapshot currentSnapshot;
+    BuildSnapshot(m_assetsRoot, currentSnapshot);
+
+    const ChangeStats changes = DiffSnapshots(m_snapshot, currentSnapshot);
+    m_snapshot = std::move(currentSnapshot);
+    ScheduleRefresh(changes);
+}
+
 void ProjectAssetWatcher::FlushPendingRefresh(IEditorContext& context) {
     if (!m_hasPendingRefresh) {
         return;
@@ -124,6 +408,7 @@ void ProjectAssetWatcher::FlushPendingRefresh(IEditorContext& context) {
 
     Resources::ResourceManager::Get().RefreshProjectAssets();
     context.GetProjectManager().RefreshCurrentFolder();
+    BuildSnapshot(m_assetsRoot, m_snapshot);
 
     Debug::Logger::Get().Info(
         Debug::LogCategory::FileSystem,
@@ -132,7 +417,9 @@ void ProjectAssetWatcher::FlushPendingRefresh(IEditorContext& context) {
          " modified=" +
          std::to_string(m_pendingChanges.modified) +
          " removed=" +
-         std::to_string(m_pendingChanges.removed)).c_str());
+         std::to_string(m_pendingChanges.removed) +
+         " backend=" +
+         (m_nativeWatcherHealthy.load() ? "native" : "polling")).c_str());
 
     m_pendingChanges.Clear();
     m_debounceSeconds = 0.0f;

editor/src/Core/ProjectAssetWatcher.h

@@ -2,9 +2,12 @@
 
 #include "Core/IEditorContext.h"
 
+#include <atomic>
 #include <cstdint>
 #include <filesystem>
+#include <mutex>
 #include <string>
+#include <thread>
 #include <unordered_map>
 
 namespace XCEngine {
@@ -12,6 +15,8 @@ namespace Editor {
 
 class ProjectAssetWatcher {
 public:
+    ~ProjectAssetWatcher();
+
     void Attach(const std::string& projectPath);
     void Detach();
     void Update(IEditorContext& context, float dt);
@@ -54,6 +59,11 @@ private:
     using Snapshot = std::unordered_map<std::string, AssetEntryState>;
 
     void RefreshProjectBinding(const std::string& projectPath);
+    void StartNativeWatcher();
+    void StopNativeWatcher();
+    void RunNativeWatcher(void* directoryHandle, std::filesystem::path watchedRoot);
+    void ConsumeNativeChanges();
+    void ScheduleRefresh(const ChangeStats& changes);
     void ScanForChanges();
     void FlushPendingRefresh(IEditorContext& context);
     static void BuildSnapshot(const std::filesystem::path& assetsRoot, Snapshot& outSnapshot);
@@ -64,8 +74,15 @@ private:
     Snapshot m_snapshot;
     ChangeStats m_pendingChanges;
     float m_scanCooldownSeconds = 0.0f;
+    float m_nativeRestartCooldownSeconds = 0.0f;
     float m_debounceSeconds = 0.0f;
     bool m_hasPendingRefresh = false;
+    std::thread m_nativeWatcherThread;
+    std::mutex m_nativeChangeMutex;
+    ChangeStats m_threadPendingChanges;
+    std::atomic<bool> m_nativeWatcherHealthy{false};
+    std::atomic<bool> m_pollingResyncRequested{false};
+    void* m_nativeStopEvent = nullptr;
 };
 
 } // namespace Editor