Fork.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "HAL/PlatformAffinity.h"
 
#ifndef DEFAULT_SERVER_FAKE_FORKS
    // Defines if the server process should always simulate forking even on platforms that do not support it.
    #define DEFAULT_SERVER_FAKE_FORKS 0
#endif
 
#ifndef DEFAULT_FORK_PROCESS_MULTITHREAD
    // Defines if forked child processes should support multithreading by default
    #define DEFAULT_FORK_PROCESS_MULTITHREAD 0
#endif
 
class FRunnable;
class FRunnableThread;
 
enum class EForkProcessRole : uint8
{
    Parent,
    Child,
};
 
class FForkProcessHelper 
{
public:
 
    static CORE_API bool IsForkRequested();
 
    static CORE_API bool IsForkedMultithreadInstance();
 
    static CORE_API bool IsForkedChildProcess();
 
    static CORE_API void SetIsForkedChildProcess(uint16 ChildIndex=1);
 
    static CORE_API uint16 GetForkedChildProcessIndex();
 
    static CORE_API void OnForkingOccured();
 
    static CORE_API bool SupportsMultithreadingPostFork();
 
    static CORE_API FRunnableThread* CreateForkableThread(
        class FRunnable* InRunnable,
        const TCHAR* InThreadName,
        uint32 InStackSize = 0,
        EThreadPriority InThreadPri = TPri_Normal,
        uint64 InThreadAffinityMask = FPlatformAffinity::GetNoAffinityMask(),
        EThreadCreateFlags InCreateFlags = EThreadCreateFlags::None,
        bool bAllowPreFork = false
    );
 
    static CORE_API void LowLevelPreFork();
 
    static CORE_API void LowLevelPostForkParent();
 
    static CORE_API void LowLevelPostForkChild(uint16 ChildIndex=1);
};