AuroraRuntime/Source/IO/Loop/LSSemaphore.Linux.cpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: LSSemaphore.Linux.cpp
    Date: 2022-4-5
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "LSSemaphore.hpp"
#include "LSFromFdNonblocking.hpp"

namespace Aurora::IO::Loop
{
    LSSemaphore::LSSemaphore()
    {

    }

    LSSemaphore::LSSemaphore(AuUInt32 initialCount)
    {
        Init(initialCount);
    }

    LSSemaphore::LSSemaphore(int handle, int tag)
    {
        this->handle = handle;
    }

    LSSemaphore::~LSSemaphore()
    {
        if ((this->handle != 0) &&
            (this->handle != -1))
        {
            ::close(AuExchange(this->handle, -1));
        }
    }

    void LSSemaphore::Init(AuUInt32 initialCount)
    {
        handle = ::eventfd(initialCount, EFD_SEMAPHORE | EFD_NONBLOCK | EFD_CLOEXEC);
    }

    bool LSSemaphore::TryInit(AuUInt32 initialCount)
    {
        this->Init(initialCount);
        return this->HasValidHandle();
    }

    bool LSSemaphore::IsSignaledNonblocking()
    {
        AuUInt64 oldSemaphoreValue {};
        return ::read(this->handle, &oldSemaphoreValue, sizeof(oldSemaphoreValue)) == 8;
    }

    bool LSSemaphore::AddOne()
    {
        AuUInt64 plsNoOverflow { 1 };

        if (::write(this->handle, &plsNoOverflow, sizeof(plsNoOverflow)) != 8)
        {
            // todo push error
            return false;
        }

        return true;
    }

    bool LSSemaphore::AddMany(AuUInt32 uCount)
    {
        AuUInt64 plsNoOverflow { uCount };

        if (::write(this->handle, &plsNoOverflow, sizeof(plsNoOverflow)) != 8)
        {
            // todo push error
            return false;
        }

        return true;
    }

    bool LSSemaphore::OnTrigger(AuUInt handle)
    {
        return IsSignaledNonblocking();
    }

    bool LSSemaphore::IsSignaled()
    {
        return IsSignaledFromNonblockingImpl(this, this, &LSSemaphore::IsSignaledNonblocking, true);
    }

    bool LSSemaphore::IsSignaledExt(AuUInt8 uFlags)
    {
        return IsSignaledFromNonblockingImpl(this, this, &LSSemaphore::IsSignaledNonblocking, !(uFlags & kFlagLSTryNoIOAlerts));
    }

    bool LSSemaphore::WaitOn(AuUInt32 timeout)
    {
        return LSHandle::WaitOn(timeout);
    }
    
    ELoopSource LSSemaphore::GetType()
    {
        return ELoopSource::eSourceSemaphore;
    }

    AUKN_SYM AuSPtr<ILSSemaphore> NewLSSemaphoreSlow(AuUInt32 initialCount)
    {
        auto pSemaphore = AuMakeShared<LSSemaphore>(initialCount);
        if (!pSemaphore)
        {
            return {};
        }

        if (!pSemaphore->HasValidHandle())
        {
            return {};
        }

        return pSemaphore;
    }
}