observable_value.hpp

// Copyright Take Vos 2022.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "observable.hpp"
#include "rcu.hpp"
#include "unfair_mutex.hpp"
 
namespace hi::inline v1 {
template<typename>
class observer;
 
template<typename T>
class observable_value final : public observable {
public:
    using value_type = T;
    using path_type = observable_msg::path_type;
 
    ~observable_value() = default;
 
    constexpr observable_value() noexcept : _rcu()
    {
        _rcu.emplace(value_type{});
    }
 
    template<typename... Args>
    constexpr observable_value(Args&&...args) noexcept : _rcu()
    {
        _rcu.emplace(std::forward<Args>(args)...);
    }
 
    [[nodiscard]] void const *read() const noexcept override
    {
        return _rcu.get();
    }
 
    [[nodiscard]] void *copy(void const *ptr) const noexcept override
    {
        return _rcu.copy(static_cast<value_type const *>(ptr));
    }
 
    void commit(void *ptr) noexcept override
    {
        _rcu.commit(static_cast<value_type *>(ptr));
    }
 
    void abort(void *ptr) const noexcept override
    {
        _rcu.abort(static_cast<value_type *>(ptr));
    }
 
    void read_lock() const noexcept override
    {
        _rcu.lock();
    }
 
    void read_unlock() const noexcept override
    {
        _rcu.unlock();
    }
 
    void write_lock() const noexcept override
    {
        _write_mutex.lock();
        read_lock();
    }
 
    void write_unlock() const noexcept override
    {
        read_unlock();
        _write_mutex.unlock();
    }
private:
    rcu<value_type> _rcu;
    mutable unfair_mutex _write_mutex;
};
 
}