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

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

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

namespace Aurora::IO::Loop
{
    LSEvent::LSEvent(bool triggered, bool atomicRelease, bool permitMultipleTriggers) : atomicRelease_(atomicRelease)
    {
        Init(triggered);
    }

    LSEvent::LSEvent(int handle, bool triggered, bool atomicRelease) : atomicRelease_(atomicRelease)
    {
        this->handle = handle;
    }

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

    bool LSEvent::OnTrigger(AuUInt handle)
    {
        AuUInt64 oldSemaphoreValue {};

        if (!this->atomicRelease_)
        {
            return true;
        }

        return ::read(this->handle, &oldSemaphoreValue, sizeof(oldSemaphoreValue)) == 8;
    }

    void LSEvent::Init(bool init)
    {
        this->handle = ::eventfd(init ? 1 : 0, EFD_NONBLOCK);
    }

    bool LSEvent::Set()
    {
        AuUInt64 plsNoOverflow {1};

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

        return true;
    }

    bool LSEvent::Reset()
    {
        AuUInt64 oldSemaphoreValue {0};

        // RETURN VALUE IS USELESS - Failure is to be expected
        ::read(this->handle, &oldSemaphoreValue, sizeof(oldSemaphoreValue));

        return true;
    }

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

    bool LSEvent::WaitOn(AuUInt32 timeout)
    {
        return LSHandle::WaitOn(timeout);
    }
    
    bool LSEvent::IsSignaledNonblocking()
    {
        if (!this->atomicRelease_)
        {
            fd_set set;
            struct timeval tv {};

            FD_ZERO(&set);
            FD_SET(this->handle, &set);

            auto active = ::select(this->handle + 1, &set, NULL, NULL, &tv);
            if (active == -1)
            {
                // todo push error
                return false;
            }

            return active == 1;
        }
        else
        {
            AuUInt64 oldSemaphoreValue {};
            return ::read(this->handle, &oldSemaphoreValue, sizeof(oldSemaphoreValue)) == 8;
        }
    }

    ELoopSource LSEvent::GetType()
    {
        return ELoopSource::eSourceEvent;
    }

    AUKN_SYM AuSPtr<ILSEvent> NewLSEvent(bool triggered, bool atomicRelease, bool permitMultipleTriggers)
    {
        auto event = AuMakeShared<LSEvent>(triggered, atomicRelease, permitMultipleTriggers);
        if (!event)
        {
            return {};
        }

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

        return event;
    }
}