vcmi/lib/UnlockGuard.h

/*
 * UnlockGuard.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#pragma once

namespace vstd
{
namespace detail
{
template<typename Mutex>
class unlock_policy
{
protected:
	void unlock(Mutex & m)
	{
		m.unlock();
	}
	void lock(Mutex & m)
	{
		m.lock();
	}
};

template<typename Mutex>

class unlock_shared_policy
{
protected:
	void unlock(Mutex & m)
	{
		m.unlock_shared();
	}
	void lock(Mutex & m)
	{
		m.lock_shared();
	}
};

}


//similar to boost::lock_guard but UNlocks for the scope + assertions
template<typename Mutex, typename LockingPolicy = detail::unlock_policy<Mutex>>
class unlock_guard : LockingPolicy
{
private:
	Mutex * m;

	explicit unlock_guard(unlock_guard &);
	unlock_guard & operator=(unlock_guard &);

public:
	explicit unlock_guard(Mutex & m_)
		: m(&m_)
	{
		this->unlock(*m);
	}

	unlock_guard()
	{
		m = nullptr;
	}

	unlock_guard(unlock_guard && other)
		: m(other.m)
	{
		other.m = nullptr;
	}

	void release()
	{
		m = nullptr;
	}

	~unlock_guard()
	{
		if(m)
			this->lock(*m);
	}
};

template<typename Mutex>
unlock_guard<Mutex, detail::unlock_policy<Mutex>> makeUnlockGuard(Mutex & m_)
{
	return unlock_guard<Mutex, detail::unlock_policy<Mutex>>(m_);
}
template<typename Mutex>
unlock_guard<Mutex, detail::unlock_policy<Mutex>> makeEmptyGuard(Mutex &)
{
	return unlock_guard<Mutex, detail::unlock_policy<Mutex>>();
}
template<typename Mutex>
unlock_guard<Mutex, detail::unlock_policy<Mutex>> makeUnlockGuardIf(Mutex & m_, bool shallUnlock)
{
	return shallUnlock ? makeUnlockGuard(m_) : unlock_guard<Mutex, detail::unlock_policy<Mutex>>();
}
template<typename Mutex>
unlock_guard<Mutex, detail::unlock_shared_policy<Mutex>> makeUnlockSharedGuard(Mutex & m_)
{
	return unlock_guard<Mutex, detail::unlock_shared_policy<Mutex>>(m_);
}
template<typename Mutex>
unlock_guard<Mutex, detail::unlock_shared_policy<Mutex>> makeUnlockSharedGuardIf(Mutex & m_, bool shallUnlock)
{
	return shallUnlock ? makeUnlockSharedGuard(m_) : unlock_guard<Mutex, detail::unlock_shared_policy<Mutex>>();
}

typedef unlock_guard<boost::shared_mutex, detail::unlock_shared_policy<boost::shared_mutex>> unlock_shared_guard;
}