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private memset ( byte dest, int value, |
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| dest | byte | |
| value | int | |
| count | ||
| return | int | |
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;
}
}
public StreamRange LockValue(long nodeIndex, uint valueIndex, long?minimumSize, out BTreeValue *pValue, out ushort keyType)
{
var result = AccessNode(nodeIndex, true);
unchecked {
pValue = (BTreeValue *)(result.Pointer + BTreeNode.OffsetOfValues + (valueIndex * BTreeValue.Size));
keyType = pValue->KeyType;
pValue->KeyType = 0;
}
var lockLength = pValue->DataLength;
if ((minimumSize.HasValue) && (minimumSize.Value > lockLength))
{
lockLength = (uint)minimumSize.Value;
var oldPosition = pValue->DataOffset;
var oldLength = pValue->DataLength + pValue->ExtraDataBytes;
pValue->DataOffset = (uint)AllocateDataSpace(ref lockLength).Value;
pValue->ExtraDataBytes = (uint)(lockLength - oldLength);
using (var oldDataRange = DataStream.AccessRange(oldPosition, oldLength))
using (var dataRange = DataStream.AccessRange(pValue->DataOffset, pValue->DataLength)) {
Native.memmove(dataRange.Pointer, oldDataRange.Pointer, new UIntPtr(pValue->DataLength));
Native.memset(oldDataRange.Pointer, 0, new UIntPtr(pValue->DataLength));
}
FreelistPut(oldPosition, oldLength);
}
return(result);
}
public void Clear()
{
IndexStream.Clear();
KeyStream.Clear();
DataStream.Clear();
Native.memset(_HeaderRange.Pointer, 0, new UIntPtr(BTreeHeader.Size));
Native.memset(_FreelistIndexRange.Pointer, 0, new UIntPtr(FreelistIndex.Size));
InitializeBTree();
}
public static void ZeroBytes(byte *ptr, long offset, uint count)
{
Native.memset(ptr + offset, 0, new UIntPtr((uint)count));
}