AuroraRuntime/Source/Threading/Primitives/RWLock.hpp

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

    File: RWLock.hpp
    Date: 2021-6-12
    Author: Reece
***/
#pragma once

namespace Aurora::Threading::Primitives
{
    class RWLockImpl;

    template<bool isread>
    class RWLockAccessView : public IWaitable
    {
    public:
        RWLockAccessView(RWLockImpl &impl) : parent_(impl)
        {

        }

        bool Lock(AuUInt64 timeout) override
        {
            if constexpr (isread)
            {
                return parent_.LockRead(timeout);
            }
            else
            {
                return parent_.LockWrite(timeout);
            }
        }

        bool TryLock() override
        {
            if constexpr (isread)
            {
                return parent_.TryLockRead();
            }
            else
            {
                return parent_.TryLockWrite();
            }
        }

        bool HasOSHandle(AuMach &mach) override
        {
            return false;
        }

        bool HasLockImplementation() override
        {
            return true;
        }

        void Lock() override
        {
            SysAssert(Lock(0));
        }

        void Unlock() override
        {
            if constexpr (isread)
            {
                parent_.UnlockRead();
            }
            else
            {
                parent_.UnlockWrite();
            }
        }

    private:
        RWLockImpl &parent_;
    };

    class RWLockImpl : public RWLock
    {
    public:
        RWLockImpl();
        ~RWLockImpl();
        
        bool LockRead(AuUInt64 timeout);
        bool LockWrite(AuUInt64 timeout);
        bool TryLockRead();
        bool TryLockWrite();
        void UnlockRead();
        void UnlockWrite();

        bool UpgradeReadToWrite(AuUInt64 timeout) override;
        
        IWaitable *AsReadable() override;
        IWaitable *AsWritable() override;

        bool Init();
        
    private:
        
        RWLockAccessView<true>  read_;
        RWLockAccessView<false> write_;

        ConditionMutexUnique_t mutex_;
        ConditionVariableUnique_t  condition_;
        std::atomic<int> state_;
        std::atomic<bool> elevaterPending_;
    };
}