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//
// SharedMemory.h
//
// Library: Foundation
// Package: Processes
// Module: SharedMemory
//
// Definition of the SharedMemory class.
//
// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_SharedMemory_INCLUDED
#define Foundation_SharedMemory_INCLUDED
#include "Poco/Foundation.h"
#include <algorithm>
#include <cstddef>
namespace Poco {
class SharedMemoryImpl;
class File;
class Foundation_API SharedMemory
/// Create and manage a shared memory object.
///
/// A SharedMemory object has value semantics, but
/// is implemented using a handle/implementation idiom.
/// Therefore, multiple SharedMemory objects can share
/// a single, reference counted SharedMemoryImpl object.
{
public:
enum AccessMode
{
AM_READ = 0,
AM_WRITE
};
SharedMemory();
/// Default constructor creates an unmapped SharedMemory object.
/// No clients can connect to an unmapped SharedMemory object.
SharedMemory(const std::string& name, std::size_t size, AccessMode mode, const void* addrHint = 0, bool server = true);
/// Creates or connects to a shared memory object with the given name.
///
/// For maximum portability, name should be a valid Unix filename and not
/// contain any slashes or backslashes.
///
/// An address hint can be passed to the system, specifying the desired
/// start address of the shared memory area. Whether the hint
/// is actually honored is, however, up to the system. Windows platform
/// will generally ignore the hint.
///
/// If server is set to true, the shared memory region will be unlinked
/// by calling shm_unlink() (on POSIX platforms) when the SharedMemory object is destroyed.
/// The server parameter is ignored on Windows platforms.
SharedMemory(const File& file, AccessMode mode, const void* addrHint = 0);
/// Maps the entire contents of file into a shared memory segment.
///
/// An address hint can be passed to the system, specifying the desired
/// start address of the shared memory area. Whether the hint
/// is actually honored is, however, up to the system. Windows platform
/// will generally ignore the hint.
SharedMemory(const SharedMemory& other);
/// Creates a SharedMemory object by copying another one.
~SharedMemory();
/// Destroys the SharedMemory.
SharedMemory& operator = (const SharedMemory& other);
/// Assigns another SharedMemory object.
void swap(SharedMemory& other);
/// Swaps the SharedMemory object with another one.
char* begin() const;
/// Returns the start address of the shared memory segment.
/// Will be NULL for illegal segments.
char* end() const;
/// Returns the one-past-end end address of the shared memory segment.
/// Will be NULL for illegal segments.
private:
SharedMemoryImpl* _pImpl;
};
//
// inlines
//
inline void SharedMemory::swap(SharedMemory& other)
{
using std::swap;
swap(_pImpl, other._pImpl);
}
} // namespace Poco::Poco
#endif // Foundation_SharedMemory_INCLUDED
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