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// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "winapi-common" project.
// For details, see https://github.com/egor-tensin/winapi-common.
// Distributed under the MIT License.
#pragma once
#include "handle.hpp"
#include <boost/config.hpp>
#include <cstddef>
#include <memory>
#include <string>
#include <type_traits>
#include <utility>
namespace winapi {
class SharedMemory {
public:
static SharedMemory create(const std::string& name, std::size_t nb);
static SharedMemory open(const std::string& name);
// VS 2013 won't generate these automatically:
SharedMemory(SharedMemory&&) BOOST_NOEXCEPT_OR_NOTHROW;
SharedMemory& operator=(SharedMemory) BOOST_NOEXCEPT_OR_NOTHROW;
void swap(SharedMemory&) BOOST_NOEXCEPT_OR_NOTHROW;
SharedMemory(const SharedMemory&) = delete;
void* get() const { return m_addr.get(); }
void* ptr() const { return get(); }
private:
struct Unmap {
void operator()(void*) const;
};
SharedMemory() = default;
SharedMemory(Handle&& handle, void* addr) : m_handle{std::move(handle)}, m_addr{addr} {}
Handle m_handle;
std::unique_ptr<void, Unmap> m_addr;
};
inline void swap(SharedMemory& a, SharedMemory& b) BOOST_NOEXCEPT_OR_NOTHROW {
a.swap(b);
}
template <typename T>
class SharedObject {
public:
typedef typename std::aligned_storage<sizeof(T), __alignof(T)>::type AlignedType;
template <typename... Args>
static SharedObject create(const std::string& name, Args&&... args) {
SharedObject obj{SharedMemory::create(name, sizeof(AlignedType))};
new (obj.ptr()) T(std::forward<Args>(args)...);
obj.m_destruct = true;
return obj;
}
static SharedObject open(const std::string& name) {
SharedObject obj{SharedMemory::open(name)};
return obj;
}
SharedObject(SharedObject&& other) BOOST_NOEXCEPT_OR_NOTHROW
: m_shmem{std::move(other.m_shmem)},
m_destruct{other.m_destruct} {}
SharedObject& operator=(SharedObject other) BOOST_NOEXCEPT_OR_NOTHROW {
swap(other);
return *this;
}
~SharedObject() {
if (m_destruct && ptr()) {
ptr()->~T();
}
}
void swap(SharedObject& other) BOOST_NOEXCEPT_OR_NOTHROW {
using std::swap;
swap(m_shmem, other.m_shmem);
swap(m_destruct, other.m_destruct);
}
T* ptr() const { return reinterpret_cast<T*>(m_shmem.ptr()); }
T& get() const { return *ptr(); }
T* operator->() const { return ptr(); }
T& operator*() const { return get(); }
private:
explicit SharedObject(SharedMemory&& shmem) : m_shmem{std::move(shmem)} {}
SharedMemory m_shmem;
// Destruct only once, no matter the number of mappings.
bool m_destruct = false;
SharedObject(const SharedObject&) = delete;
};
template <typename T>
inline void swap(SharedObject<T>& a, SharedObject<T>& b) BOOST_NOEXCEPT_OR_NOTHROW {
a.swap(b);
}
} // namespace winapi
namespace std {
template <>
inline void swap(winapi::SharedMemory& a, winapi::SharedMemory& b) BOOST_NOEXCEPT_OR_NOTHROW {
a.swap(b);
}
template <typename T>
inline void swap(winapi::SharedObject<T>& a, winapi::SharedObject<T>& b) BOOST_NOEXCEPT_OR_NOTHROW {
a.swap(b);
}
} // namespace std
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