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/************************************************************************
*
* Copyright (C) 2009-2023 IRCAD France
* Copyright (C) 2012-2020 IHU Strasbourg
*
* This file is part of Sight.
*
* Sight is free software: you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Sight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Sight. If not, see <https://www.gnu.org/licenses/>.
*
***********************************************************************/
#pragma once
#include "core/com/exception/worker_changed.hpp"
#include <core/exceptionmacros.hpp>
#include <core/mt/types.hpp>
#include <functional>
#include <utility>
namespace sight::core::com::util
{
/**
* @brief Weak functor class.
* Store a zero-arg-function and a weak pointer on an object. The WeakCall is
* callable only once.
* A bad_weak_ptr exception is thrown if the weak_ptr is expired when operator()
* is called
* A core::com::exception::WorkerChanged exception is thrown if the target slot
* worker changed since weakcall request
* @tparam T Stored object type.
* @tparam R Stored function return type.
*/
template<typename T, typename R>
struct weak_call
{
weak_call(const std::shared_ptr<T const>& _ptr, std::function<R()> _f) :
m_weak_ptr(_ptr),
m_func(std::move(_f))
{
}
weak_call(
const std::shared_ptr<T const>& _weak_ptr,
std::function<R()> _f,
const std::shared_ptr<core::thread::worker>& _m,
const std::shared_ptr<T const>& _shared_ptr
) :
m_weak_ptr(_weak_ptr),
m_shared_ptr(_shared_ptr),
m_func(std::move(_f)),
m_worker(_m)
{
}
~weak_call()
= default;
//------------------------------------------------------------------------------
R operator()() const
{
auto ptr = this->m_weak_ptr.lock();
if(!ptr)
{
m_worker.reset();
// will throw an exception because m_weakPtr is expired
throw std::bad_weak_ptr();
}
core::mt::read_lock lock(ptr->m_worker_mutex);
auto shared_ptr = this->m_shared_ptr;
std::shared_ptr<core::thread::worker> worker = m_worker.lock();
if(worker && ptr->m_worker != worker)
{
//Worker changed since WeakCall creation
SIGHT_THROW_EXCEPTION(core::com::exception::worker_changed("Worker changed since WeakCall creation"));
}
this->m_weak_ptr.reset();
this->m_shared_ptr.reset();
return this->m_func();
}
protected:
// Maintain a pointer to the callee. Allows to not proceed if the callee has been destroyed in between.
mutable std::weak_ptr<T const> m_weak_ptr;
// This is used to extend the life of a wrapped slot, which is needed if the signal is disconnected before the
// call. Indeed, otherwise, a wrapped slot is not owned by anyone else the connected signal.
mutable std::shared_ptr<T const> m_shared_ptr;
std::function<R()> m_func;
mutable std::weak_ptr<core::thread::worker> m_worker;
};
/// Returns weak call from given object and function.
template<typename T, typename R>
weak_call<T, R> weakcall(const std::shared_ptr<T const>& _ptr, std::function<R()> _f)
{
return weak_call<T, R>(_ptr, _f);
}
/// Returns weak call from given object, function and mutex.
template<typename T, typename R>
weak_call<T, R> weakcall(
const std::shared_ptr<T const>& _weak_ptr,
std::function<R()> _f,
const std::shared_ptr<core::thread::worker>& _m,
const std::shared_ptr<T const>& _shared_ptr = nullptr
)
{
return weak_call<T, R>(_weak_ptr, _f, _m, _shared_ptr);
}
} // namespace sight::core::com::util
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