refactor(filesystem): Put file existence cache behind ENABLE_FILESYSTEM_EXISTENCE_CACHE macro (#1295)

Author: xezon

Core/GameEngine/Include/Common/FileSystem.h

@@ -142,8 +142,11 @@ class FileSystem : public SubsystemInterface
 	void unloadMusicFilesFromCD();
 	AsciiString normalizePath(const AsciiString& path) const;	///< normalizes a file path. The path can refer to a directory. File path must be absolute, but does not need to exist. Returns an empty string on failure.
 	static Bool isPathInDirectory(const AsciiString& testPath, const AsciiString& basePath);	///< determines if a file path is within a base path. Both paths must be absolute, but do not need to exist.
+
 protected:
-  mutable std::map<unsigned,bool> m_fileExist;
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
+	mutable std::map<unsigned,bool> m_fileExist;
+#endif
 };
 
 extern FileSystem*	TheFileSystem;

Core/GameEngine/Include/Common/GameDefines.h

@@ -53,3 +53,9 @@
 #ifndef USE_BUFFERED_IO
 #define USE_BUFFERED_IO (1)
 #endif
+
+// Enable cache for local file existence. Reduces amount of disk accesses for better performance,
+// but decreases file existence correctness and runtime stability, if a cached file is deleted on runtime.
+#ifndef ENABLE_FILESYSTEM_EXISTENCE_CACHE
+#define ENABLE_FILESYSTEM_EXISTENCE_CACHE (1)
+#endif

Core/GameEngine/Source/Common/System/FileSystem.cpp

@@ -179,11 +179,14 @@ File*		FileSystem::openFile( const Char *filename, Int access )
 	if ( TheLocalFileSystem != NULL )
 	{
 		file = TheLocalFileSystem->openFile( filename, access );
+
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
 		if (file != NULL && (file->getAccess() & File::CREATE))
 		{
 			unsigned key = TheNameKeyGenerator->nameToLowercaseKey(filename);
 			m_fileExist[key] = true;
 		}
+#endif
 	}
 
 	if ( (TheArchiveFileSystem != NULL) && (file == NULL) )
@@ -202,23 +205,31 @@ Bool FileSystem::doesFileExist(const Char *filename) const
 {
 	USE_PERF_TIMER(FileSystem)
 
-  unsigned key=TheNameKeyGenerator->nameToLowercaseKey(filename);
-  std::map<unsigned,bool>::iterator i=m_fileExist.find(key);
-  if (i!=m_fileExist.end())
-    return i->second;
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
+	unsigned key=TheNameKeyGenerator->nameToLowercaseKey(filename);
+	std::map<unsigned,bool>::iterator i=m_fileExist.find(key);
+	if (i!=m_fileExist.end())
+		return i->second;
+#endif
 
 	if (TheLocalFileSystem->doesFileExist(filename)) 
-  {
-    m_fileExist[key]=true;
+	{
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
+		m_fileExist[key]=true;
+#endif
 		return TRUE;
 	}
 	if (TheArchiveFileSystem->doesFileExist(filename)) 
-  {
-    m_fileExist[key]=true;
+	{
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
+		m_fileExist[key]=true;
+#endif
 		return TRUE;
 	}
 
-  m_fileExist[key]=false;
+#if ENABLE_FILESYSTEM_EXISTENCE_CACHE
+	m_fileExist[key]=false;
+#endif
 	return FALSE;
 }