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SharedMemory.h

//
// SharedMemory.h
//
// $Id: //poco/1.3/Foundation/include/Poco/SharedMemory.h#2 $
//
// Library: Foundation
// Package: Processes
// Module:  SharedMemory
//
// Definition of the SharedMemory class.
//
// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_SharedMemory_INCLUDED
#define Foundation_SharedMemory_INCLUDED


#include "Poco/Foundation.h"
#include <algorithm>
#include <cstddef>


namespace Poco {


class SharedMemoryImpl;
class File;


00055 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 false, 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:
00118       SharedMemoryImpl* _pImpl;
};


//
// inlines
//
00125 inline void SharedMemory::swap(SharedMemory& other)
{
      using std::swap;
      swap(_pImpl, other._pImpl);
}


} // namespace Poco::Poco


#endif // Foundation_SharedMemory_INCLUDED

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