khanat-opennel-code/code/nel/include/nel/misc/shared_memory.h

108 lines
3.3 KiB
C++

// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
// Copyright (C) 2010 Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#ifndef NL_SHARED_MEMORY_H
#define NL_SHARED_MEMORY_H
#include "types_nl.h"
#ifdef NL_OS_WINDOWS
#include <map>
#endif
namespace NLMISC {
#ifdef NL_OS_WINDOWS
typedef const char *TSharedMemId;
#else
typedef key_t TSharedMemId;
#endif
/* Helpers:
* toSharedMemId: converts an integer to TSharedMemId
* NL_SMID: format type used for printf syntax. Ex: nldebug( "Segment %"NL_SMID" was created", sharedMemId );
*/
#ifdef NL_OS_WINDOWS
#define toSharedMemId( id ) toString( "NeLSM_%d", id ).c_str()
#define NL_SMID "s"
#else
#define toSharedMemId( id ) (id)
#define NL_SMID "d"
#endif
/**
* Encapsulation of shared memory APIs.
* Using file mapping under Windows, System V shared memory (shm) under Linux.
*
* Note: under Linux, an option could be added to prevent a segment to be swapped out.
*
* \author Olivier Cado
* \author Nevrax France
* \date 2002
*/
class CSharedMemory
{
public:
// Constructor
//CSharedMemory();
/**
* Create a shared memory segment and get access to it. The id must not be used.
* The id 0x3a732235 is reserved by the NeL memory manager.
* \return Access address of the segment of the choosen size
*/
static void * createSharedMemory( TSharedMemId sharedMemId, uint32 size );
/**
* Get access to an existing shared memory segment. The id must be used.
* \return Access address of the segment. Its size was determined at the creation.
*/
static void * accessSharedMemory( TSharedMemId sharedMemId );
/**
* Close (detach) a shared memory segment, given the address returned by createSharedMemory()
* or accessSharedMemory(). Must be called by each process that called createSharedMemory()
* or accessSharedMemory().
*/
static bool closeSharedMemory( void * accessAddress );
/**
* Destroy a shared memory segment (must be called by the process that created the segment,
* not by the accessors).
*
* "Rescue feature": set "force" to true if a segment was created and left out of
* control (meaning a new createSharedMemory() with the same sharedMemId fails), but
* before, make sure the segment really belongs to you!
*
* Note: this method does nothing under Windows, destroying is automatic.
* Under Unix, the segment will actually be destroyed after the last detach
* (quoting shmctl man page). It means after calling destroySharedMemory(), the
* segment is still accessible by another process until it calls closeSharedMemory().
*/
static void destroySharedMemory( TSharedMemId sharedMemId, bool force=false );
};
} // NLMISC
#endif // NL_SHARED_MEMORY_H
/* End of shared_memory.h */