QueuedThreadPool.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Containers/Array.h"
#include "GenericPlatform/GenericPlatformAffinity.h"
#include "Templates/Function.h"
 
class IQueuedWork;
 
enum class EQueuedWorkPriority : uint8
{
    Blocking = 0,
    Highest = 1,
    High = 2,
    Normal = 3,
    Low = 4,
    Lowest = 5,
    Count
};
 
inline const TCHAR* LexToString(EQueuedWorkPriority Priority)
{
    switch (Priority)
    {
    case EQueuedWorkPriority::Blocking:
        return TEXT("Blocking");
    case EQueuedWorkPriority::Highest:
        return TEXT("Highest");
    case EQueuedWorkPriority::High:
        return TEXT("High");
    case EQueuedWorkPriority::Normal:
        return TEXT("Normal");
    case EQueuedWorkPriority::Low:
        return TEXT("Low");
    case EQueuedWorkPriority::Lowest:
        return TEXT("Lowest");
    case EQueuedWorkPriority::Count:
    default:
        check(false);
        return TEXT("Unknown");
    }
}
 
class FThreadPoolPriorityQueue
{
public:
    CORE_API FThreadPoolPriorityQueue();
 
    CORE_API void Enqueue(IQueuedWork* InQueuedWork, EQueuedWorkPriority InPriority = EQueuedWorkPriority::Normal);
 
    CORE_API bool Retract(IQueuedWork* InQueuedWork);
 
    CORE_API IQueuedWork* Dequeue(EQueuedWorkPriority* OutDequeuedWorkPriority = nullptr);
 
    CORE_API IQueuedWork* Peek(EQueuedWorkPriority* OutDequeuedWorkPriority = nullptr) const;
 
    CORE_API void Reset();
 
    int32 Num() const { return NumQueuedWork; }
 
    CORE_API void Sort(EQueuedWorkPriority InPriorityBucket, TFunctionRef<bool (const IQueuedWork* A, const IQueuedWork* B)> Predicate);
private:
    int32 FirstNonEmptyQueueIndex = 0;
    TArray<TArray<IQueuedWork*>, TInlineAllocator<static_cast<int32>(EQueuedWorkPriority::Lowest) + 1>> PriorityQueuedWork;
    TAtomic<int32> NumQueuedWork;
};
 
class FQueuedThreadPool
{
public:
    virtual bool Create(uint32 InNumQueuedThreads, uint32 StackSize = (32 * 1024), EThreadPriority ThreadPriority = TPri_Normal, const TCHAR* Name = TEXT("UnknownThreadPool")) = 0;
 
    virtual bool CreateForkable(uint32 InNumQueuedThreads, uint32 StackSize = (32 * 1024), EThreadPriority ThreadPriority = TPri_Normal, const TCHAR* Name = TEXT("UnknownThreadPool"))
    {
        return false;
    }
 
    virtual void Destroy() = 0;
 
    virtual void AddQueuedWork( IQueuedWork* InQueuedWork, EQueuedWorkPriority InQueuedWorkPriority = EQueuedWorkPriority::Normal) = 0;
 
    virtual bool RetractQueuedWork(IQueuedWork* InQueuedWork) = 0;
 
    virtual int32 GetNumThreads() const = 0;
 
public:
            CORE_API FQueuedThreadPool();
    CORE_API virtual    ~FQueuedThreadPool();
 
public:
 
    static CORE_API FQueuedThreadPool* Allocate();
 
    static CORE_API uint32 OverrideStackSize;
};
 
extern CORE_API FQueuedThreadPool* GThreadPool;
 
extern CORE_API FQueuedThreadPool* GIOThreadPool;
 
extern CORE_API FQueuedThreadPool* GBackgroundPriorityThreadPool;
 
#if WITH_EDITOR
extern CORE_API FQueuedThreadPool* GLargeThreadPool;
#endif