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-rw-r--r--include/winapi/shmem.hpp125
1 files changed, 125 insertions, 0 deletions
diff --git a/include/winapi/shmem.hpp b/include/winapi/shmem.hpp
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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