/***
    Copyright (C) 2021-2024 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuConditionMutex.Win32.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuConditionMutex.Generic.hpp"
#include "SMTYield.hpp"
#include "AuProcAddresses.NT.hpp"
#include "../AuWakeInternal.hpp"

#if !defined(_AURUNTIME_GENERICCM)

namespace Aurora::Threading::Primitives
{
    Win32ConditionMutex::Win32ConditionMutex()
    {
    #if !defined(AURORA_FORCE_SRW_LOCKS)
    #else
        ::InitializeSRWLock(&this->lock_);
    #endif
    }

    Win32ConditionMutex::~Win32ConditionMutex()
    {

    }

    bool Win32ConditionMutex::TryLock()
    {
    #if defined(AURORA_FORCE_SRW_LOCKS)
        return ::TryAcquireSRWLockExclusive(&this->lock_);
    #else
        if (ThrdCfg::gPreferNtCondMutexSpinTryLock)
        {
            return this->TryLockHeavy();
        }
        else
        {
            return this->TryLockNoSpin();
        }
    #endif
    }

    bool Win32ConditionMutex::TryLockHeavy()
    {
        return DoTryIfAlderLake([=]()
        {
            return this->TryLockNoSpin();
        }, &this->lock_);
    }

    bool Win32ConditionMutex::TryLockNoSpin()
    {
    #if defined(AURORA_FORCE_SRW_LOCKS)
        return ::TryAcquireSRWLockExclusive(&this->lock_);
    #else
        return AuAtomicTestAndSet(&this->lock_.uWaitCount, 0) == 0;
    #endif
    }

    void Win32ConditionMutex::Lock()
    {
    #if defined(AURORA_FORCE_SRW_LOCKS)
        ::AcquireSRWLockExclusive(&this->lock_);
    #else

        if (this->TryLockHeavy())
        {
            return;
        }

        while (!this->TryLockNoSpin())
        {
            auto &uValueRef = this->lock_.uWaitCount;
            auto uValue = uValueRef | 1;

            if (AuAtomicCompareExchange(&uValueRef, uValue + kFutexBitWait, uValue) == uValue)
            {
                if (gUseNativeWaitCondvar)
                {
                    auto uCurrentValue = uValue + kFutexBitWait;
                    InternalLTSWaitOnAddressHighRes((void *)&uValueRef, &uCurrentValue, sizeof(uCurrentValue), 0);
                }
                else
                {
                    pNtWaitForKeyedEvent(gKeyedEventHandle, (void *)&uValueRef, 0, NULL);
                    AuAtomicSub(&uValueRef, kFutexBitWake);
                }
            }
        }
    #endif
    }

    void Win32ConditionMutex::Unlock()
    {
    #if defined(AURORA_FORCE_SRW_LOCKS)
        ::ReleaseSRWLockExclusive(&this->lock_);
    #else
        // Mirrors: ./AuMutex.NT.cpp
        // keep this codeblock in parity
        // defer to the comments in that source file

        auto &uValueRef = this->lock_.uWaitCount;

        AuAtomicClearU8Lock(&uValueRef);

        while (true)
        {
            auto uOld = uValueRef;
            auto uValue = uOld;

            if (uValue & 1)
            {
                return;
            }

            if (uValue < kFutexBitWait)
            {
                return;
            }

            if (gUseNativeWaitCondvar)
            {
                if (AuAtomicCompareExchange(&uValueRef, uValue - kFutexBitWait, uValue) == uValue)
                {
                    InternalLTSWakeOne((void *)&uValueRef);
                    return;
                }
            }
            else
            {
                if (uValue & kFutexBitWake)
                {
                    if (AuAtomicCompareExchange(&uValueRef, uValue, uValue) == uValue)
                    {
                        return;
                    }
                    else
                    {
                        SMPPause();
                        continue;
                    }
                }

                if (AuAtomicCompareExchange(&uValueRef, uValue - kFutexBitWait + kFutexBitWake, uValue) == uValue)
                {
                    pNtReleaseKeyedEvent(gKeyedEventHandle, (void *)&uValueRef, 0, NULL);
                    return;
                }
            }
  
            SMPPause();
        }
    #endif
    }

    AuUInt Win32ConditionMutex::GetOSHandle()
    {
        return reinterpret_cast<AuUInt>(&this->lock_);
    }

    AUKN_SYM IConditionMutex *ConditionMutexNew()
    {
        return _new ConditionMutexImpl();
    }

    AUKN_SYM void ConditionMutexRelease(IConditionMutex *pMutex)
    {
        AuSafeDelete<ConditionMutexImpl *>(pMutex);
    }

    AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, ConditionMutex, ConditionMutexImpl)
}

#endif