IasCache.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/StringView.h"
#include "IO/IoStatus.h"
#include "Memory/MemoryFwd.h"
#include "Tasks/Task.h"
#include "Templates/UniquePtr.h"
 
class FIoBuffer;
class FIoReadOptions;
struct FIoHash;
 
#define UE_ALLOW_DROP_CACHE !UE_BUILD_SHIPPING
 
namespace UE::IoStore
{
 
class IIasCache
{
public:
    virtual ~IIasCache() = default;
 
    virtual void Abandon() = 0;
 
    virtual void Drop() = 0;
 
    virtual bool ContainsChunk(const FIoHash& Key) const = 0;
 
    virtual EIoErrorCode Get(const FIoHash& Key, FIoBuffer& OutData) = 0;
 
    virtual void Materialize(const FIoHash& Key, FIoBuffer& Dest, EIoErrorCode& Status, UE::Tasks::FTaskEvent DoneEvent) = 0;
 
    virtual void Cancel(FIoBuffer& GivenDest) = 0;
 
    virtual FIoStatus Put(const FIoHash& Key, FIoBuffer& Data) = 0;
 
    virtual FIoStatus Evict(const FIoHash& Key) = 0;
};
 
struct FIasCacheConfig
{
    struct FRate
    {
        uint32  Allowance = 16 << 20;
        uint32  Ops = 32;
        uint32  Seconds = 60;
    };
 
    struct FDemand
    {
        uint8   Threshold = 30;
        uint8   Boost = 60;
        uint8   SuperBoost = 87;
    };
 
    FStringView Name = TEXT("ias");
    uint64      DiskQuota = 512ull << 20;
    uint32      MemoryQuota = 2 << 20;
    uint32      JournalQuota = 4 << 20; // description in JournalCache.cpp
    uint32      JournalMagic = 0; // can be used to invalidate cache
    FRate       WriteRate;
    FDemand     Demand;
    bool        DropCache = false;
};
 
TUniquePtr<IIasCache> MakeIasCache(const TCHAR* RootDir, const FIasCacheConfig& Config, class FDiskCacheGovernor& Governor);
 
} // namespace UE::IoStore