public Win32MemoryMapPager(int pageSize, string file,
long?initialFileSize = null,
Win32NativeFileAttributes options = Win32NativeFileAttributes.Normal,
Win32NativeFileAccess access = Win32NativeFileAccess.GenericRead | Win32NativeFileAccess.GenericWrite)
: base(pageSize)
{
Win32NativeMethods.SYSTEM_INFO systemInfo;
Win32NativeMethods.GetSystemInfo(out systemInfo);
AllocationGranularity = systemInfo.allocationGranularity;
_access = access;
_memoryMappedFileAccess = _access == Win32NativeFileAccess.GenericRead
? MemoryMappedFileAccess.Read
: MemoryMappedFileAccess.ReadWrite;
_handle = Win32NativeFileMethods.CreateFile(file, access,
Win32NativeFileShare.Read | Win32NativeFileShare.Write | Win32NativeFileShare.Delete, IntPtr.Zero,
Win32NativeFileCreationDisposition.OpenAlways, options, IntPtr.Zero);
if (_handle.IsInvalid)
{
int lastWin32ErrorCode = Marshal.GetLastWin32Error();
throw new IOException("Failed to open file storage of Win32MemoryMapPager for " + file,
new Win32Exception(lastWin32ErrorCode));
}
_fileInfo = new FileInfo(file);
var streamAccessType = _access == Win32NativeFileAccess.GenericRead
? FileAccess.Read
: FileAccess.ReadWrite;
_fileStream = new FileStream(_handle, streamAccessType);
_totalAllocationSize = _fileInfo.Length;
if (_access.HasFlag(Win32NativeFileAccess.GenericWrite) ||
_access.HasFlag(Win32NativeFileAccess.GenericAll) ||
_access.HasFlag(Win32NativeFileAccess.FILE_GENERIC_WRITE))
{
var fileLength = _fileStream.Length;
if (fileLength == 0 && initialFileSize.HasValue)
{
fileLength = initialFileSize.Value;
}
if (_fileStream.Length == 0 || (fileLength % AllocationGranularity != 0))
{
fileLength = NearestSizeToAllocationGranularity(fileLength);
Win32NativeFileMethods.SetFileLength(_handle, fileLength);
}
_totalAllocationSize = fileLength;
}
NumberOfAllocatedPages = _totalAllocationSize / _pageSize;
PagerState.Release();
PagerState = CreatePagerState();
}
public Win32PageFileBackedMemoryMappedPager(string name, long?initialFileSize = null)
{
_name = name;
Win32NativeMethods.SYSTEM_INFO systemInfo;
Win32NativeMethods.GetSystemInfo(out systemInfo);
AllocationGranularity = systemInfo.allocationGranularity;
_totalAllocationSize = initialFileSize.HasValue ? NearestSizeToAllocationGranularity(initialFileSize.Value) : systemInfo.allocationGranularity;
_instanceId = Interlocked.Increment(ref _counter);
PagerState.Release();
Debug.Assert(AllocationGranularity % PageSize == 0);
NumberOfAllocatedPages = _totalAllocationSize / PageSize;
PagerState = CreateInitialPagerState(_totalAllocationSize);
}