);
static TAutoConsoleVariable<int32> CVarPSOFileCacheSaveAfterPSOsLogged(
														   TEXT("r.ShaderPipelineCache.SaveAfterPSOsLogged"),
														   0,
														   TEXT("Set the number of PipelineStateObjects to log before automatically saving. 0 will disable automatic saving (which is the default now, as automatic saving is found to be broken)."),
														   ECVF_Default | ECVF_RenderThreadSafe
														   );
 
static TAutoConsoleVariable<int32> CVarPSOFileCacheAutoSaveTime(

 * - PSOs are logged as they are encountered as the Unreal Engine does not provide facility to cook them offline, so this system will only collect PSOs which are actually used to render.
 * - As such you must either manually play through the game to collect logs or automate the process which is beyond the scope of this code.
 * - The data can be saved at any time by calling FShaderPipelineCache::SavePipelineFileCache and this can happen automatically after a given number of PSOs by setting r.ShaderPipelineCache.SaveAfterPSOsLogged = X where X is the desired number of PSOs to log before saving (0 will disable auto-save).
 * - Log files are shader platform specific to reduce overheads.
 *
 * Notes:
 * - The open cache file can be changed by closing the existing file with ClosePipelineFileCache (which implicitly Fast saves) and then opening a new one with OpenPipelineFileCache.
 * - Different files can be used to minimise PSO compilation by having a file per-scalability bucket (i.e. one file for Low, one for Med, one for High).
 * - When logging if you switch files only new entries from after the switch will be logged, which means you will miss any PSOs that should have been logged prior to switching. This prevents polluting the cache with unexpected entries.
 * - The UnrealEd.MergeShaderPipelineCaches command-let can be used to merge cache files with the same file-version, shader platform and game-version.
 *
 * File Locations & Packaging:
 * - The writable cache file is always stored in the User Saved directory.
 * - The game can also provide an immutable copy within its Game Content directory which will be used as the initial or seed data.
 * - Having generated logs in development and merged them with UnrealEd.MergeShaderPipelineCaches they should be packaged inside the Gane Content directory for the relevant platform.
 *
 * Requirements:
 * - FShaderCodeLibrary must be enabled via Project Settings > Packaging > "Share Material Shader Code".
 * - Enabling "Native Shader Libraries" is optional, but strongly preferred for Metal.
 */
class FShaderPipelineCache : public FTickableObjectRenderThread
{
	// the FShaderPipelineCacheTask class represents a pipeline precompile of a single PSO file cache.
	friend class FShaderPipelineCacheTask;
public:
	/**
	 * Initializes the shader pipeline cache for the desired platform, called by the engine.
	 * The shader platform is used only to load the initial pipeline cache and can be changed by closing & reopening the cache if necessary.
	 */
	static RENDERCORE_API void Initialize(EShaderPlatform Platform);
	/** Terminates the shader pipeline cache, called by the engine. */
	static RENDERCORE_API void Shutdown();

	/** Pauses precompilation. */
	static RENDERCORE_API void PauseBatching();
	
	enum class BatchMode
	{
		Background, // The maximum batch size is defined by r.ShaderPipelineCache.BackgroundBatchSize
		Fast, // The maximum batch size is defined by r.ShaderPipelineCache.BatchSize
		Precompile // The maximum batch size is defined by r.ShaderPipelineCache.PrecompileBatchSize
	};
	
	/** Sets the precompilation batching mode. */
	static RENDERCORE_API void SetBatchMode(BatchMode Mode);
	
	/** Resumes precompilation batching. */
	static RENDERCORE_API void ResumeBatching();
	
	/** true if pipeline cache(s) are precompiling. */
	static RENDERCORE_API bool IsPrecompiling();

	/** Returns the number of pipelines waiting for precompilation of the current PSOFC task. 
		if there are multiple PSOFCs pending this will return a minimum value of 1. It may increase as subsequent caches are processed.*/
	static RENDERCORE_API uint32 NumPrecompilesRemaining();
    
	/** Opens the shader pipeline cache file with either the LastOpened setting if available, or the project name otherwise */

															 ECVF_Default | ECVF_RenderThreadSafe
															 );
static TAutoConsoleVariable<int32> CVarPSOFileCacheSaveAfterPSOsLogged(
														   TEXT("r.ShaderPipelineCache.SaveAfterPSOsLogged"),
														   0,
														   TEXT("Set the number of PipelineStateObjects to log before automatically saving. 0 will disable automatic saving (which is the default now, as automatic saving is found to be broken)."),
														   ECVF_Default | ECVF_RenderThreadSafe
														   );
 

file
function     bool FShaderPipelineCache::ReadyForAutoSave

{
	bool bAutoSave = false;
	uint32 SaveAfterNum = CVarPSOFileCacheSaveAfterPSOsLogged.GetValueOnAnyThread();
	uint32 NumLogged = FPipelineFileCacheManager::NumPSOsLogged();

	const double TimeSinceSave = FPlatformTime::Seconds() - LastAutoSaveTime;

	// autosave if its enabled, and we have more than the desired number, or it's been a while since our last save
	if (SaveAfterNum > 0 &&