AuroraRuntime/Include/Aurora/Threading/LockGuardTry.hpp

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

    File: LockGuardTry.hpp
    Date: 2021-12-25
    Author: Reece
***/
#pragma once

namespace Aurora::Threading
{
    template<typename T>
    class TryLockGuard
    {
    private:
        using Internal_t = AuRemovePointer_t<T>;
        bool bLockSuccessful;
        
    public:

        TryLockGuard(T &lock) 
        {
            if constexpr (AuIsPointer_v<T>)
            {
                annoying_ = lock;
            }
            else
            {
                annoying_ = &lock;
            }

            if constexpr (AuIsBaseOfTemplate<AURORA_RUNTIME_AU_SHARED_PTR, Internal_t>::value || AuIsBaseOfTemplate<AURORA_RUNTIME_AU_UNIQUE_PTR, Internal_t>::value)
            {
                bLockSuccessful = annoying_->get()->TryLock();
            }
            else
            {
                bLockSuccessful = annoying_->TryLock();
            }
        }

        TryLockGuard(T &&lock) 
        {
            if constexpr (AuIsPointer_v<T>)
            {
                annoying_ = lock;
            }
            else
            {
                annoying_ = &lock;
            }

            if constexpr (AuIsBaseOfTemplate<AURORA_RUNTIME_AU_SHARED_PTR, Internal_t>::value || AuIsBaseOfTemplate<AURORA_RUNTIME_AU_UNIQUE_PTR, Internal_t>::value)
            {
                bLockSuccessful = annoying_->get()->TryLock();
            }
            else
            {
                bLockSuccessful = annoying_->TryLock();
            }
        }
        
        ~TryLockGuard()
        {
            if (!bLockSuccessful)
            {
                return;
            }

            if constexpr (AuIsBaseOfTemplate<AURORA_RUNTIME_AU_SHARED_PTR, Internal_t>::value || AuIsBaseOfTemplate<AURORA_RUNTIME_AU_UNIQUE_PTR, Internal_t>::value)
            {
                annoying_->get()->Unlock();
            }
            else
            {
                annoying_->Unlock();
            }
        }

        const bool Locked() const
        {
            return bLockSuccessful;
        }
    private:
        AuConditional_t<AuIsPointer_v<T>, T, T*> annoying_;
    };
    
    
    // Named try-lock guard. Use when you wish to poll ::Locked(), otherwise use the auto-return macros
    // There is no point in using anonymous lock handles w/o checking the lock state or auto-returning
    // Where variable = an iwaitable-like interface reference, pointer, or shared pointer; value = reference to a boolean
    //       name = name of handle variable
    #define AU_TRY_LOCK_GUARD_NAMED(variable, name) Aurora::Threading::TryLockGuard<decltype(variable)>  name(variable);

    /// @hideinitializer
    #define AU_TRY_LOCK_GUARD_RET_NAMED(variable, value, name) AU_TRY_LOCK_GUARD_NAMED(variable, name) if (!(name.Locked())) return value;

    /// @hideinitializer
    #define AU_TRY_LOCK_GUARD_RET_COUNTERVAL(variable, value, counter) AU_TRY_LOCK_GUARD_RET_NAMED(variable, value, AU_CONCAT(__stack_lock, counter))

    // where variable = an iwaitable-like interface reference, pointer, or shared pointer; value = reference to a boolean
    //       value    = failure return object
    #define AU_TRY_LOCK_GUARD_RET_VAL(variable, value) AU_TRY_LOCK_GUARD_RET_COUNTERVAL(variable, value, AU_WHAT(__COUNTER__))

    // where variable = an iwaitable-like interface reference, pointer, or shared pointer
    #define AU_TRY_LOCK_GUARD_RET_DEF(variable) AU_TRY_LOCK_GUARD_RET_VAL(variable, {})

    // where variable = an iwaitable-like interface reference, pointer
    #define AU_TRY_LOCK_GUARD_RET(variable) AU_TRY_LOCK_GUARD_RET_VAL(variable, )
}