// Copyright (c) 2020 by Chrono

#ifndef _SPIN_LOCK_HPP

#define _SPIN_LOCK_HPP

#include "cpplang.hpp"

BEGIN_NAMESPACE(cpp_study)

// atomic spinlock with TAS

class SpinLock final

{

public:

using this_type = SpinLock;

using atomic_type = std::atomic_flag;

public:

SpinLock() = default;

~SpinLock() = default;

SpinLock(const this_type&) = delete;

SpinLock& operator=(const this_type&) = delete;

public:

void lock() noexcept

{

for(;;) {

if (m_lock.test_and_set()) {

return;

}

std::this_thread::yield();

}

}

bool try_lock() noexcept

{

return m_lock.test_and_set();

}

void unlock() noexcept

{

m_lock.clear();

}

private:

atomic_type m_lock {false};

};

// RAII for lock

// you can change it to a template class

class SpinLockGuard final

{

public:

using this_type = SpinLockGuard;

using spin_lock_type = SpinLock;

public:

SpinLockGuard(spin_lock_type& lock) noexcept

: m_lock(lock)

{

m_lock.lock();

}

~SpinLockGuard() noexcept

{

m_lock.unlock();

}

public:

SpinLockGuard(const this_type&) = delete;

SpinLockGuard& operator=(const this_type&) = delete;

private:

spin_lock_type& m_lock;

};

END_NAMESPACE(cpp_study)

#endif //_SPIN_LOCK_HPP