MemoryMisc.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Containers/UnrealString.h"
#include "Containers/Map.h"
#include "Containers/StringView.h"
#include "Misc/StringBuilder.h"
 
#ifndef UE_MEMORY_STAT_DESCRIPTION_LENGTH_DEFAULT
#define UE_MEMORY_STAT_DESCRIPTION_LENGTH 64
#endif
 
#ifndef UE_MEMORY_STAT_PREALLOCATION_COUNT
#define UE_MEMORY_STAT_PREALLOCATION_COUNT 32
#endif
 
struct FGenericMemoryStats
{
private:
    PRAGMA_DISABLE_DEPRECATION_WARNINGS
    static constexpr int32 EntryCount = UE_MEMORY_STAT_PREALLOCATION_COUNT;
    static constexpr int32 StringLength = UE_MEMORY_STAT_DESCRIPTION_LENGTH;
    using FInternalMap = TMap<FStringView, SIZE_T, TInlineSetAllocator<EntryCount>>;
 
public:
    void Add(const FStringView& InDescription, SIZE_T InValue)
    {
        const FStringView DescriptionView = Descriptions.Emplace_GetRef(InPlace, InDescription).ToView();
        Data.FInternalMap::Add(DescriptionView, InValue);
    }
 
    SIZE_T* Find(const FStringView& InDescription)
    {
        return Data.FInternalMap::Find(InDescription);
    }
 
    const SIZE_T* Find(const FStringView& InDescription) const
    {
        return const_cast<FGenericMemoryStats*>(this)->Find(InDescription);
    }
 
    SIZE_T FindRef(const FStringView& InDescription) const
    {
        return Data.FInternalMap::FindRef(InDescription);
    }
 
    // Expose iterators only for const ranged-for iteration
    FInternalMap::TRangedForConstIterator begin() const { return Data.begin(); }
    FInternalMap::TRangedForConstIterator end() const { return Data.end(); }
 
private:
    TArray<TStringBuilder<StringLength>, TInlineAllocator<EntryCount>> Descriptions;
 
    class FGenericMemoryStatsMap : public FInternalMap
    {
    public:
        SIZE_T* Find(const FString& InDescription)
        {
            const FStringView DescriptionView(InDescription);
            return FInternalMap::Find(DescriptionView);
        }
 
        const SIZE_T* Find(const FString& InDescription) const
        {
            return const_cast<FGenericMemoryStatsMap*>(this)->Find(InDescription);
        }
 
        SIZE_T FindRef(const FString& InDescription) const
        {
            const FStringView DescriptionView(InDescription);
            return FInternalMap::FindRef(DescriptionView);
        }
    };
    PRAGMA_ENABLE_DEPRECATION_WARNINGS
 
public:
    UE_DEPRECATED(5.5, "Using Data directly is deprecated and will be made private. Use methods on FGenericMemoryStats directly.")
    FGenericMemoryStatsMap Data;
};
 
#ifndef ENABLE_MEMORY_SCOPE_STATS
#define ENABLE_MEMORY_SCOPE_STATS 0
#endif
 
// This will grab the memory stats of VM and Physical before and at the end of scope
// reporting +/- difference in memory.
// WARNING This will also capture differences in Threads which have nothing to do with the scope
#if ENABLE_MEMORY_SCOPE_STATS
class FScopedMemoryStats
{
public:
    CORE_API explicit FScopedMemoryStats(const TCHAR* Name);
 
    CORE_API ~FScopedMemoryStats();
 
private:
    const TCHAR* Text;
    const FPlatformMemoryStats StartStats;
};
#else
class FScopedMemoryStats
{
public:
    explicit FScopedMemoryStats(const TCHAR* Name) {}
};
#endif
 
#ifndef ENABLE_SHARED_MEMORY_TRACKER
#define ENABLE_SHARED_MEMORY_TRACKER 0
#endif
 
#if ENABLE_SHARED_MEMORY_TRACKER && PLATFORM_UNIX
 
class FSharedMemoryTracker
{
public:
 
    static CORE_API void PrintMemoryDiff(const TCHAR* Context);
 
 
    CORE_API explicit FSharedMemoryTracker(const FString& InContext);
    CORE_API ~FSharedMemoryTracker();
 
private:
    const FString PrintContext;
    const FExtendedPlatformMemoryStats StartStats;
};
#else
class FSharedMemoryTracker
{
public:
 
    static void PrintMemoryDiff(const TCHAR* /*Context*/) {}
 
    explicit FSharedMemoryTracker(const FString& /*InContext*/) {}
};
#endif // ENABLE_SHARED_MEMORY_TRACKER  && PLATFORM_UNIX