|
public AccessRangeUncached ( long offset, uint size, MemoryMappedFileAccess access = MemoryMappedFileAccess.ReadWrite ) : |
||
| offset | long | The offset within the stream, relative to the end of the stream header. |
| size | uint | The size of the range to access, in bytes. |
| access | MemoryMappedFileAccess | |
| return | ||
public StreamRange AccessRangeUncached(long offset, uint size, MemoryMappedFileAccess access = MemoryMappedFileAccess.ReadWrite)
{
unchecked {
long relativeOffset = offset + HeaderSize;
EnsureCapacity(relativeOffset + size);
long actualOffset;
uint actualSize;
var view = Cache.CreateViewUncached(relativeOffset, size, access, out actualOffset, out actualSize);
return new StreamRange(
this, view, relativeOffset, size, actualOffset, actualSize
);
}
}
private void EnsureFreelistExists()
{
var pHeader = (BTreeHeader *)_HeaderRange.Pointer;
if (EnableFreelist)
{
long oldOffset = 0;
if (pHeader->FreelistIndexOffset == 0)
{
uint size = FreelistIndex.Size;
long?offset = AllocateDataSpace(ref size);
if (!offset.HasValue)
{
throw new OutOfMemoryException("Unable to allocate space for freelist index in data stream.");
}
oldOffset = Interlocked.Exchange(ref pHeader->FreelistIndexOffset, offset.Value);
}
_FreelistIndexRange = DataStream.AccessRangeUncached(pHeader->FreelistIndexOffset, FreelistIndex.Size, MemoryMappedFileAccess.ReadWrite);
Native.memset(_FreelistIndexRange.Pointer, 0, new UIntPtr(FreelistIndex.Size / 4));
if (oldOffset != 0)
{
FreelistPut(oldOffset, FreelistIndex.Size);
}
}
else
{
pHeader->FreelistIndexOffset = 0;
}
}
