public Block(Slice data)
{
if (data.Length < sizeof(uint))
{
throw new Exception("bad block contents");
}
// restart points are recorded at the end of the buffer.
uint numRestarts = Coding.DecodeFixed32(data.NewSlice(data.Length - sizeof(uint), sizeof(uint)));
uint restartOffset = data.Length - (1 + numRestarts) * sizeof(uint);
// we don't really care for these except the first, but we'll parse them.
var restartPoints = new uint[numRestarts];
for (uint i = 0; i < numRestarts; ++i)
{
var offset = restartOffset + (i * sizeof(uint));
restartPoints[i] = Coding.DecodeFixed32(data.NewSlice(offset, sizeof(uint)));
}
// block data is the remaining data.
var blockData = data.NewSlice(0, restartOffset);
// parse this block.
var key = new InternalKey();
var value = blockData.NewSlice(0, 0);
uint m_current = restartPoints[0];
while (m_current < blockData.Length)
{
Slice?p = blockData.NewSlice(m_current);
// Decode next entry
p = DecodeEntry(p, out uint shared, out uint non_shared, out uint value_length);
if (p == null || key.Length < shared)
{
throw new Exception("bad entry in block");
}
else
{
key.Resize(shared);
key.Append(p.NewSlice(0, non_shared));
value.Update(p.Offset + non_shared, value_length);
// don't add deleted keys to the dictionary.
var parsedKey = new Key(key.Slice(0, key.Length));
if (parsedKey.Type == KeyType.kTypeValue)
{
m_keys.Add(parsedKey.UserKey);
m_values.Add(value.ToArray());
}
}
m_current = value.Offset + value.Length;
}
}
public static Footer DecodeFrom(Slice slice)
{
uint startOffset = slice.Offset;
uint startLength = slice.Length;
uint magic_lo = Coding.DecodeFixed32(slice.NewSlice(kEncodedLength - 8, 4));
uint magic_hi = Coding.DecodeFixed32(slice.NewSlice(kEncodedLength - 4, 4));
ulong magic = (unchecked ((ulong)magic_hi) << 32) | unchecked ((ulong)magic_lo);
if (magic != kTableMagicNumber)
{
throw new Exception("not an sstable (bad magic number)");
}
var metaIndexHandle = BlockHandle.DecodeFrom(slice);
var indexHandle = BlockHandle.DecodeFrom(slice);
slice.Update(startOffset + kEncodedLength, startLength - kEncodedLength);
return(new Footer(metaIndexHandle, indexHandle));
}