共享内存的使用

BOOL CShareMemoryImage::InitMap()

{

EnterCriticalSection(&m_cs);

char szBuf[256] = { 0 };

// 获取最小分页大小

SYSTEM_INFO sysinfo;

GetSystemInfo(&sysinfo);

DWORD dwAllocationGranularity = sysinfo.dwAllocationGranularity;

INT64 dwMemoryFileSize = 1024*1024; //指定内存映射文件大小

// 必须要为dwAllocationGranularity(64K)的整数倍

int left = dwMemoryFileSize % dwAllocationGranularity;

if (left != 0)

{

dwMemoryFileSize += (dwAllocationGranularity - left);

}

DWORD dwError = 0;

// 文件方式创建共享内存

HANDLE hFile = CreateFileA(fileName.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

if (hFile == INVALID_HANDLE_VALUE)

{

dwError = GetLastError();

sprintf_s(szBuf, "[CShareMemoryImage]CreateFile failed,GetLastError = %d\n", dwError);

DebugStringA(szBuf);

LeaveCriticalSection(&m_cs);

return FALSE;

}

DebugStringA("[CShareMemoryImage]CreateFile success!\n");

DWORD high = (dwMemoryFileSize >> 32) & 0xFFFFFFFF;// 高32位

DWORD low = dwMemoryFileSize & 0xFFFFFFFF;// 低32位

HANDLE hFileMapping = CreateFileMappingA(

hFile, // system paging file INVALID_HANDLE_VALUE

NULL, // security attributes

PAGE_READWRITE, // protection

high, // high-order DWORD of size

low, // low-order DWORD of size

fileName.c_str()); // name

if (hFileMapping == NULL)

{

dwError = GetLastError();

sprintf_s(szBuf, "[CShareMemoryImage]CreateFileMapping failed,GetLastError = %d\n", dwError);

DebugStringA(szBuf);

CloseHandle(hFile);

LeaveCriticalSection(&m_cs);

return FALSE;

}

else

{

DebugStringA("[CShareMemoryImage]CreateFileMapping success!\n");

LPVOID pViewOfFile = MapViewOfFile( // 映射

hFileMapping, // handle to file-mapping object

FILE_MAP_ALL_ACCESS, // desired access

0,

0,

0); // map all file

if (pViewOfFile == NULL)

{

dwError = GetLastError();

sprintf_s(szBuf, "[CShareMemoryImage]MapViewOfFile failed,GetLastError = %d\n", dwError);

DebugStringA(szBuf);

CloseHandle(hFile);

CloseHandle(hFileMapping);

LeaveCriticalSection(&m_cs);

return FALSE;

}

else

{

sprintf_s(szBuf, "[CShareMemoryImage]MapViewOfFile success,fileName = %s\n", fileName.c_str());

DebugStringA(szBuf);

}

}

LeaveCriticalSection(&m_cs);

return TRUE;

}