EM_Task/CoreUObject/Public/Serialization/AsyncPackageLoader.h

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "UObject/Object.h"
#include "UObject/UObjectArray.h"
#include "Stats/Stats2.h"

DECLARE_STATS_GROUP_VERBOSE(TEXT("Async Load"), STATGROUP_AsyncLoad, STATCAT_Advanced);
DECLARE_CYCLE_STAT(TEXT("Async Loading Time"), STAT_AsyncLoadingTime, STATGROUP_AsyncLoad);

DECLARE_STATS_GROUP(TEXT("Async Load Game Thread"), STATGROUP_AsyncLoadGameThread, STATCAT_Advanced);

DECLARE_CYCLE_STAT(TEXT("PostLoadObjects GT"), STAT_FAsyncPackage_PostLoadObjectsGameThread, STATGROUP_AsyncLoadGameThread);
DECLARE_CYCLE_STAT(TEXT("TickAsyncLoading GT"), STAT_FAsyncPackage_TickAsyncLoadingGameThread, STATGROUP_AsyncLoadGameThread);
DECLARE_CYCLE_STAT(TEXT("Flush Async Loading GT"), STAT_FAsyncPackage_FlushAsyncLoadingGameThread, STATGROUP_AsyncLoadGameThread);
DECLARE_CYCLE_STAT(TEXT("CreateClusters GT"), STAT_FAsyncPackage_CreateClustersGameThread, STATGROUP_AsyncLoadGameThread);

enum class ENotifyRegistrationType;
enum class ENotifyRegistrationPhase;

extern const FName PrestreamPackageClassNameLoad;

/** Returns true if we're inside a FGCScopeLock */
extern bool IsGarbageCollectionLocked();

bool IsFullyLoadedObj(UObject* Obj);

bool IsNativeCodePackage(UPackage* Package);

/** Checks if the object can have PostLoad called on the Async Loading Thread */
bool CanPostLoadOnAsyncLoadingThread(UObject* Object);

template <typename T>
void ClearFlagsAndDissolveClustersFromLoadedObjects(T& LoadedObjects)
{
    const EObjectFlags ObjectLoadFlags = RF_NeedLoad | RF_NeedPostLoad | RF_NeedPostLoadSubobjects | RF_WasLoaded;
    for (UObject* ObjRef: LoadedObjects)
    {
        if (ObjRef)
        {
            ObjRef->AtomicallyClearFlags(ObjectLoadFlags);
            if (ObjRef->HasAnyInternalFlags(EInternalObjectFlags::ClusterRoot))
            {
                GUObjectClusters.DissolveCluster(ObjRef);
            }
        }
    }
}

class IAsyncPackageLoader;
class FPackageIndex;
class LinkerInstancingContext;

class IEDLBootNotificationManager
{
public:
    virtual ~IEDLBootNotificationManager()                                                                                           = default;

    virtual bool AddWaitingPackage(void* Pkg, FName PackageName, FName ObjectName, FPackageIndex Import, bool bIgnoreMissingPackage) = 0;
    virtual bool ConstructWaitingBootObjects()                                                                                       = 0;
    virtual bool FireCompletedCompiledInImports(bool bFinalRun = false)                                                              = 0;
    virtual bool IsWaitingForSomething()                                                                                             = 0;
};

/** Structure that holds the async loading thread ini settings */
struct FAsyncLoadingThreadSettings
{
    bool bAsyncLoadingThreadEnabled;
    bool bAsyncPostLoadEnabled;

    FAsyncLoadingThreadSettings();

    /** Gets the ALT settigns from ini (or command line). */
    static FAsyncLoadingThreadSettings& Get();
};

/**
 * Asynchronous package loader interface.
 */
class IAsyncPackageLoader
{
public:
    virtual ~IAsyncPackageLoader() {}

    /**
     * Initialize loading.
     */
    virtual void InitializeLoading() = 0;

    /**
     * Shut down loading.
     */
    virtual void ShutdownLoading() = 0;

    virtual void StartThread()     = 0;

    /**
     * Asynchronously load a package.
     *
     * @param	InName					Name of package to load
     * @param	InGuid					GUID of the package to load, or nullptr for "don't care"
     * @param	InPackageToLoadFrom		If non-null, this is another package name. We load from this package name, into a (probably new) package named InName
     * @param	InCompletionDelegate	Delegate to be invoked when the packages has finished streaming
     * @param	InPackageFlags			Package flags used to construct loaded package in memory
     * @param	InPIEInstanceID			Play in Editor instance ID
     * @param	InPackagePriority		Loading priority
     * @return Unique ID associated with this load request (the same package can be associated with multiple IDs).
     */
    virtual int32 LoadPackage(
        const FString& InPackageName,
        const FGuid* InGuid,
        const TCHAR* InPackageToLoadFrom,
        FLoadPackageAsyncDelegate InCompletionDelegate,
        EPackageFlags InPackageFlags,
        int32 InPIEInstanceID,
        int32 InPackagePriority,
        const FLinkerInstancingContext* InstancingContext) = 0;

    /**
     * Process all currently loading package requests.
     *
     * @param bUseTimeLimit			Whether to use time limit or not
     * @param bUseFullTimeLimit
     * @param TimeLimit				Time limit
     */
    virtual EAsyncPackageState::Type ProcessLoading(bool bUseTimeLimit, bool bUseFullTimeLimit, float TimeLimit) = 0;

    /**
     * Process all loading package requests until completion predicate is satisfied.
     *
     * @param CompletionPredicate		Completion predicate
     * @param TimeLimit					Time limit
     */
    virtual EAsyncPackageState::Type ProcessLoadingUntilComplete(TFunctionRef<bool()> CompletionPredicate, float TimeLimit) = 0;

    /**
     * Cancels streaming.
     *
     * Note: Called from Game Thread.
     */
    virtual void CancelLoading() = 0;

    /**
     * Suspends async loading thread
     *
     * Note: Called from Game Thread.
     */
    virtual void SuspendLoading() = 0;

    /**
     * Resumes async loading thread
     *
     * Note: Called from Game Thread.
     */
    virtual void ResumeLoading() = 0;

    /**
     * Flush pending loading request(s).
     *
     * Note: Called from Game Thread.
     */
    virtual void FlushLoading(int32 PackageId) = 0;

    /**
     *	Returns the number of queued packages.
     */
    virtual int32 GetNumQueuedPackages() = 0;

    /**
     *	Returns the number of loading packages.
     */
    virtual int32 GetNumAsyncPackages() = 0;

    /**
     * [GAME THREAD] Gets the load percentage of the specified package
     * @param PackageName Name of the package to return async load percentage for
     * @return Percentage (0-100) of the async package load or -1 of package has not been found
     */
    virtual float GetAsyncLoadPercentage(const FName& PackageName) = 0;

    /**
     *	Returns whether the package loader is suspended or not.
     */
    virtual bool IsAsyncLoadingSuspended() = 0;

    /**
     *	Returns whether in package loader background thread or not.
     */
    virtual bool IsInAsyncLoadThread() = 0;

    /**
     * Returns whether loading packages with multiple threads.
     * Note: GIsInitialLoad guards the package loader from creating background threads too early.
     *
     */
    virtual bool IsMultithreaded() = 0;

    /**
     * Returns whether packages are currently being loaded on a background thread.
     * Note: GIsInitialLoad guards the package loader from creating background threads too early.
     *
     */
    virtual bool IsAsyncLoadingPackages()                                                      = 0;

    virtual void NotifyConstructedDuringAsyncLoading(UObject* Object, bool bSubObject)         = 0;

    virtual void NotifyUnreachableObjects(const TArrayView<FUObjectItem*>& UnreachableObjects) = 0;

    virtual void FireCompletedCompiledInImport(void* AsyncPackage, FPackageIndex Import)       = 0;

protected:
    static int32 GetNextRequestId();

private:
    static FThreadSafeCounter NextPackageRequestId;
};

// Stats for ChartCreation.cpp
extern COREUOBJECT_API double GFlushAsyncLoadingTime;
extern COREUOBJECT_API uint32 GFlushAsyncLoadingCount;
extern COREUOBJECT_API uint32 GSyncLoadCount;

extern COREUOBJECT_API void ResetAsyncLoadingStats();

// Time limit
extern COREUOBJECT_API int32 GWarnIfTimeLimitExceeded;
extern COREUOBJECT_API float GTimeLimitExceededMultiplier;
extern COREUOBJECT_API float GTimeLimitExceededMinTime;

void IsTimeLimitExceededPrint(
    double InTickStartTime,
    double CurrentTime,
    double LastTestTime,
    float InTimeLimit,
    const TCHAR* InLastTypeOfWorkPerformed  = nullptr,
    UObject* InLastObjectWorkWasPerformedOn = nullptr);