AuroraRuntime/Source/Threading/Primitives/AuEvent.cpp

/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Event.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuEvent.hpp"
#include "SMPYield.hpp"

namespace Aurora::Threading::Primitives
{
    EventImpl::EventImpl(bool bTriggered, bool bAtomicRelease, bool bPermitMultipleTriggers) :
        triggered_(bTriggered),
        atomicRelease_(bAtomicRelease),
        permitMultipleTriggers_(bPermitMultipleTriggers),
        condition_(AuUnsafeRaiiToShared(&this->mutex_))
    {}

    EventImpl::~EventImpl() {}

    bool EventImpl::Init()
    {
        return true;
    }

    bool EventImpl::Lock(AuUInt64 timeout /*=0*/)
    {
        return LockNS(AuMSToNS<AuUInt64>(timeout));
    }

    bool EventImpl::LockNS(AuUInt64 timeout /*=0*/)
    {
        AU_LOCK_GUARD(this->mutex_);

        AuInt64 uStartTime = Time::SteadyClockNS();
        AuInt64 uEndTime = uStartTime + timeout;

        while (!AtomicIsEventSet())
        {
            AuUInt32 uTimeoutMs {};

            if (timeout)
            {
                uStartTime = Time::SteadyClockNS();
                if (uStartTime >= uEndTime)
                {
                    return false;
                }

                uTimeoutMs = AuNSToMS<AuUInt64>(uEndTime - uStartTime);
                if (!uTimeoutMs)
                {
                    this->mutex_.Unlock();
                    SMPPause();
                    AuThreading::ContextYield();
                    this->mutex_.Lock();
                    continue;
                }
            }

            if (!this->condition_.WaitForSignal(uTimeoutMs))
            {
                continue;
            }
        }

        if (this->atomicRelease_)
        {
            this->triggered_ = false;
        }

        return true;
    }

    bool EventImpl::TryLock()
    {
        AU_LOCK_GUARD(mutex_);

        return AtomicIsEventSet();
    }

    bool EventImpl::AtomicIsEventSet()
    {
        if (!this->triggered_) return false;

        if (this->atomicRelease_) this->triggered_ = false;

        return true;
    }

    void EventImpl::Reset()
    {
        this->mutex_.Lock();
        this->triggered_ = false;
        this->mutex_.Unlock();
    }

    void EventImpl::Set()
    {
        AU_LOCK_GUARD(this->mutex_);
        SysAssertExp((this->permitMultipleTriggers_) || (!this->triggered_), "Can not trigger an awake event object");
        this->triggered_ = true;
        this->condition_.Broadcast();
    }

    bool EventImpl::HasOSHandle(AuMach &mach)
    {
        mach = 0;
        return false;
    }

    bool EventImpl::HasLockImplementation()
    {
        return true;
    }

    void EventImpl::Lock()
    {
        auto ok = Lock(0);
        SysAssert(ok);
    }

    void EventImpl::Unlock()
    {
        // Unlike the other types, unlock is ways a nop
    }

    AUKN_SYM IEvent *EventNew(bool bTriggered, bool bAtomicRelease, bool bPermitMultipleTriggers)
    {
        auto event = _new EventImpl(bTriggered, bAtomicRelease, bPermitMultipleTriggers);
        if (!event)
        {
            return nullptr;
        }

        if (!event->Init())
        {
            EventRelease(event);
            return nullptr;
        }
        
        return event;
    }

    AUKN_SYM void EventRelease(IEvent *pEvent)
    {
        AuSafeDelete<EventImpl *>(pEvent);
    }
}