filesystem: got a Idea for initial faster times

source/modules/filesystem.cpp

@@ -59,12 +59,14 @@ static ConVar holylib_filesystem_usesearchpathcache("holylib_filesystem_usesearc
 
 static ConVar holylib_filesystem_precachehandle("holylib_filesystem_precachehandle", "1", 0,
 	"If enabled, it will try to predict which file it will open next and open the file to keep a handle ready to be opened.");
+static ConVar holylib_filesystem_savesearchcache("holylib_filesystem_savesearchcache", "1", 0,
+	"If enabled, it will write the search cache into a file and restore it when starting, using it to improve performance.");
 
 
 // Optimization Idea: When Gmod calls GetFileTime, we could try to get the filehandle in parallel to have it ready when gmod calls it.
 // We could also cache every FULL searchpath to not have to look up a file every time.  
 
-IThreadPool* pFileSystemPool = NULL;
+static IThreadPool* pFileSystemPool = NULL;
 
 static void OnThreadsChange(IConVar* convar, const char* pOldValue, float flOldValue)
 {
@@ -312,6 +314,68 @@ static void ShowPredictionErrosCmd(const CCommand &args)
 }
 static ConCommand showpredictionerrors("holylib_filesystem_showpredictionerrors", ShowPredictionErrosCmd, "Shows all prediction errors that ocurred", 0);
 
+struct SaveCacheEntry {
+	char pathID[24];
+	char path[128];
+	char absolutePath[255];
+};
+
+struct SaveCache {
+	unsigned int version = 1;
+	unsigned int usedPaths = 0;
+	SaveCacheEntry paths[1 << 14]; // Support 16k entries for now
+};
+
+static void WriteSaveCache(const CCommand& args)
+{
+	FileHandle_t handle = g_pFullFileSystem->Open("holylib_searchcache.dat", "wb", "MOD_WRITE");
+	if (handle)
+	{
+		SaveCache* savecache = new SaveCache;
+		for (auto& [strPath, cache] : m_SearchCache)
+		{
+			for (auto& [strEntry, storeID] : cache)
+			{
+				SaveCacheEntry& entry = savecache->paths[savecache->usedPaths++];
+				V_strcpy(entry.pathID, strPath.data());
+				V_strcpy(entry.path, strEntry.data());
+				g_pFullFileSystem->RelativePathToFullPath(strEntry.data(), strPath.data(), entry.absolutePath, sizeof(entry.absolutePath));
+			}
+		}
+
+		g_pFullFileSystem->Write(savecache, sizeof(SaveCache), handle);
+		g_pFullFileSystem->Close(handle);
+		Msg("holylib: successfully wrote searchcache file\n");
+	} else {
+		Warning("holylib: Failed to open searchcache file!\n");
+	}
+}
+static ConCommand writesearchcache("holylib_filesystem_writesearchcache", WriteSaveCache, "Writes the save cache into a file", 0);
+
+static void InitFileSystem(IFileSystem* pFileSystem)
+{
+	g_pFullFileSystem = pFileSystem;
+
+	if (holylib_filesystem_savesearchcache.GetBool())
+	{
+		FileHandle_t handle = g_pFullFileSystem->Open("holylib_searchcache.dat", "rb", "MOD_WRITE");
+		if (handle)
+		{
+			SaveCache* savecache = new SaveCache;
+			g_pFullFileSystem->Read(savecache, sizeof(SaveCache), handle);
+			g_pFullFileSystem->Close(handle);
+			//if (g_pFileSystemModule.InDebug())
+				Msg("holylib - filesystem: Loaded searchcache file (%i)\n", savecache->usedPaths);
+		} else {
+			if (g_pFileSystemModule.InDebug())
+				Msg("holylib - filesystem: Failed to find searchcache file\n");
+		}
+	}
+
+	if (g_pFileSystemModule.InDebug())
+		Msg("holylib - filesystem: Initialized filesystem\n");
+}
+
 inline void OnFileHandleOpen(FileHandle_t handle, const char* pFileMode)
 {
 	if (pFileMode[0] == 'r') // I see a potential crash, but this should never happen.
@@ -327,7 +391,7 @@ static FileHandle_t hook_CBaseFileSystem_FindFileInSearchPath(void* filesystem,
 		return detour_CBaseFileSystem_FindFileInSearchPath.GetTrampoline<Symbols::CBaseFileSystem_FindFileInSearchPath>()(filesystem, openInfo);
 
 	if (!g_pFullFileSystem)
-		g_pFullFileSystem = (IFileSystem*)filesystem;
+		InitFileSystem((IFileSystem*)filesystem);
 
 	VPROF_BUDGET("HolyLib - CBaseFileSystem::FindFile", VPROF_BUDGETGROUP_OTHER_FILESYSTEM);
 
@@ -396,7 +460,7 @@ static long hook_CBaseFileSystem_FastFileTime(void* filesystem, const CSearchPat
 		return detour_CBaseFileSystem_FastFileTime.GetTrampoline<Symbols::CBaseFileSystem_FastFileTime>()(filesystem, path, pFileName);
 
 	if (!g_pFullFileSystem)
-		g_pFullFileSystem = (IFileSystem*)filesystem;
+		InitFileSystem((IFileSystem*)filesystem);
 
 	VPROF_BUDGET("HolyLib - CBaseFileSystem::FastFileTime", VPROF_BUDGETGROUP_OTHER_FILESYSTEM);
 
@@ -453,7 +517,7 @@ static bool hook_CBaseFileSystem_FixUpPath(IFileSystem* filesystem, const char *
 	VPROF_BUDGET("HolyLib - CBaseFileSystem::FixUpPath", VPROF_BUDGETGROUP_OTHER_FILESYSTEM);
 
 	if (!g_pFullFileSystem)
-		g_pFullFileSystem = (IFileSystem*)filesystem;
+		InitFileSystem((IFileSystem*)filesystem);
 
 	V_strncpy( pFixedUpFileName, pFileName, sizeFixedUpFileName );
 	V_FixSlashes( pFixedUpFileName, CORRECT_PATH_SEPARATOR );