/***
    Copyright (C) 2023 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuConditionMutex.Linux.cpp
    Date: 2023-8-11
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuConditionMutex.Generic.hpp"
#include "SMTYield.hpp"

#if !defined(_AURUNTIME_GENERICCV) 
#include <Source/Time/Time.hpp>

namespace Aurora::Threading::Primitives
{
    #define barrier() __asm__ __volatile__("sfence": : :"memory")
    #define compilerReorderBarrier() __asm__ __volatile__("": : :"memory")

    LinuxConditionMutex::LinuxConditionMutex()
    {

    }

    LinuxConditionMutex::~LinuxConditionMutex()
    {
        
    }

    bool LinuxConditionMutex::TryLock()
    {
        if (gRuntimeConfig.threadingConfig.bPreferLinuxCondMutexSpinTryLock)
        {
            return TryLockHeavy();
        }
        else
        {
            return TryLockNoSpin();
        }
    }

    bool LinuxConditionMutex::TryLockNoSpin()
    {
        return AuAtomicTestAndSet(&this->uState_, 0) == 0;
    }

    bool LinuxConditionMutex::TryLockHeavy()
    {
        return DoTryIf([=]()
        {
            return TryLockNoSpin();
        });
    }

    void LinuxConditionMutex::Lock()
    {
        if (TryLockHeavy())
        {
            return;
        }

        AuAtomicAdd(&this->uSleeping_, 1u);

        auto state = this->uState_;
        while (!(state == 0 && 
                 AuAtomicCompareExchange<AuUInt32>(&this->uState_, 1, state) == state))
        {
           
            int ret {};
            bool bStatus {};

            do
            {
                if ((ret = futex_wait(&this->uState_, state)) == 0)
                {
                    bStatus = true;
                    break;
                }

                if (ret == EAGAIN || errno == EAGAIN)
                {
                    bStatus = true;
                    break;
                }
                
            }
            while (ret == EINTR);

            RUNTIME_ASSERT_SHUTDOWN_SAFE(bStatus, "Mutex wait failed: {}", ret)

            state = this->uState_;
        }

        AuAtomicSub(&this->uSleeping_, 1u);
    }

    void LinuxConditionMutex::Unlock()
    {
        __sync_lock_release(&this->uState_);
        compilerReorderBarrier();
        if (this->uSleeping_)
        {
            futex_wake(&this->uState_, 1);
        }
    }

    AuUInt LinuxConditionMutex::GetOSHandle()
    {
        return AuMach(&this->uState_);
    }

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

    AUKN_SYM void ConditionMutexRelease(IConditionMutex *mutex)
    {
        AuSafeDelete<LinuxConditionMutex *>(mutex);
    }

    AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, ConditionMutex, LinuxConditionMutex)
}

#endif